* Tagged Nix 0.12.

the tests) is a bad idea when $bindir = /usr and some programs (like
  perl) live there.  Fortunately it doesn't seem to be needed anymore.

Makefile.am

@@ -18,6 +18,8 @@ install-data-local: init-state
 	if ! test -e $(DESTDIR)$(sysconfdir)/nix/nix.conf; then \
 		$(INSTALL_DATA) $(srcdir)/nix.conf.example $(DESTDIR)$(sysconfdir)/nix/nix.conf; \
 	fi
+	$(INSTALL) -d $(DESTDIR)$(docdir)
+	$(INSTALL_DATA) README $(DESTDIR)$(docdir)/
 
 if INIT_STATE
 
@@ -37,10 +39,9 @@ init-state:
 	$(INSTALL) $(INIT_FLAGS) $(GROUP_WRITABLE) -d $(DESTDIR)$(localstatedir)/nix/gcroots/channels
 	ln -sfn $(localstatedir)/nix/profiles $(DESTDIR)$(localstatedir)/nix/gcroots/profiles
 	$(INSTALL) $(INIT_FLAGS) -d $(DESTDIR)$(localstatedir)/nix/userpool
-	$(INSTALL) $(INIT_FLAGS) -m 1777 -d $(DESTDIR)$(prefix)/store
+	$(INSTALL) $(INIT_FLAGS) -m 1777 -d $(DESTDIR)$(storedir)
 	$(INSTALL) $(INIT_FLAGS) $(GROUP_WRITABLE) -d $(DESTDIR)$(localstatedir)/nix/manifests
 	ln -sfn $(localstatedir)/nix/manifests $(DESTDIR)$(localstatedir)/nix/gcroots/manifests
-#	$(bindir)/nix-store --init
 
 else
 init-state:

README

@@ -1,9 +1,10 @@
-For installation and usage instructions, please read the manual, which
-can be found in `docs/manual/manual.html', and additionally at the Nix
-website at <http://www.cs.uu.nl/groups/ST/Trace/Nix>.
+Nix is a purely functional package manager.  For installation and
+usage instructions, please read the manual, which can be found in
+`docs/manual/manual.html', and additionally at the Nix website at
+<http://nixos.org/>.
 
 
 Acknowledgments
 
 This product includes software developed by the OpenSSL Project for
-use in the OpenSSL Toolkit (http://www.OpenSSL.org/)
+use in the OpenSSL Toolkit (http://www.OpenSSL.org/).

aterm-gc.supp

@@ -1,184 +1,117 @@
 {
    ATerm library conservatively scans for GC roots
    Memcheck:Cond
-   fun:mark_memory_young
-   fun:mark_phase_young
+   fun:*
+   fun:AT_collect_minor
 }
 
 {
    ATerm library conservatively scans for GC roots
    Memcheck:Cond
-   fun:AT_isValidSymbol
-   fun:mark_memory_young
-   fun:mark_phase_young
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Value4
-   fun:AT_isValidSymbol
-   fun:mark_memory_young
-   fun:mark_phase_young
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Value4
-   fun:mark_memory_young
-   fun:mark_phase_young
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Value4
-   fun:AT_isInsideValidTerm
-   fun:mark_memory_young
-   fun:mark_phase_young
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Cond
-   fun:AT_isInsideValidTerm
-   fun:mark_memory_young
-   fun:mark_phase_young
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Value4
-   fun:mark_memory_young
-   fun:mark_phase_young
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Value4
-   fun:AT_markTerm_young
-   fun:mark_memory_young
-   fun:mark_phase_young
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Cond
-   fun:AT_markTerm_young
-   fun:mark_memory_young
-   fun:mark_phase_young
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Cond
-   fun:mark_memory
-   fun:mark_phase
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Value4
-   fun:mark_memory
-   fun:mark_phase
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Cond
-   fun:AT_isValidSymbol
-   fun:mark_memory
-   fun:mark_phase
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Value4
-   fun:AT_isValidSymbol
-   fun:mark_memory
-   fun:mark_phase
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Value4
-   fun:AT_isInsideValidTerm
-   fun:mark_memory
-   fun:mark_phase
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Cond
-   fun:AT_isInsideValidTerm
-   fun:mark_memory
-   fun:mark_phase
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Cond
-   fun:AT_markTerm
-   fun:mark_memory
-   fun:mark_phase
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Value4
-   fun:AT_markTerm
-   fun:mark_memory
-   fun:mark_phase
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Value4
-   fun:AT_markTerm
-   fun:mark_memory
-   fun:mark_phase
-}
-
-{
-   ATerm library conservatively scans for GC roots
-   Memcheck:Cond
-   fun:mark_phase_young
+   fun:*
+   fun:*
    fun:AT_collect_minor
 }
 
 {
    ATerm library conservatively scans for GC roots
    Memcheck:Value4
-   fun:mark_phase_young
+   fun:*
    fun:AT_collect_minor
 }
 
 {
-   <insert a suppression name here>
-   Memcheck:Cond
-   fun:AT_isValidSymbol
-   fun:mark_phase_young
+   ATerm library conservatively scans for GC roots
+   Memcheck:Value8
+   fun:*
    fun:AT_collect_minor
 }
 
 {
-   <insert a suppression name here>
+   ATerm library conservatively scans for GC roots
    Memcheck:Value4
-   fun:AT_isValidSymbol
-   fun:mark_phase_young
+   fun:*
+   fun:*
    fun:AT_collect_minor
 }
 
 {
-   <insert a suppression name here>
-   Memcheck:Value4
-   fun:AT_isInsideValidTerm
-   fun:mark_phase_young
+   ATerm library conservatively scans for GC roots
+   Memcheck:Value8
+   fun:*
+   fun:*
    fun:AT_collect_minor
 }
 
 {
-   <insert a suppression name here>
+   ATerm library conservatively scans for GC roots
+   Memcheck:Addr4
+   fun:*
+   fun:AT_collect_minor
+}
+
+{
+   ATerm library conservatively scans for GC roots
+   Memcheck:Addr8
+   fun:*
+   fun:AT_collect_minor
+}
+
+{
+   ATerm library conservatively scans for GC roots
    Memcheck:Cond
-   fun:AT_isInsideValidTerm
-   fun:mark_phase_young
-   fun:AT_collect_minor
+   fun:*
+   fun:AT_collect
+}
+
+{
+   ATerm library conservatively scans for GC roots
+   Memcheck:Value4
+   fun:*
+   fun:AT_collect
+}
+
+{
+   ATerm library conservatively scans for GC roots
+   Memcheck:Value8
+   fun:*
+   fun:AT_collect
+}
+
+{
+   ATerm library conservatively scans for GC roots
+   Memcheck:Addr4
+   fun:*
+   fun:AT_collect
+}
+
+{
+   ATerm library conservatively scans for GC roots
+   Memcheck:Addr8
+   fun:*
+   fun:AT_collect
+}
+
+{
+   ATerm library conservatively scans for GC roots
+   Memcheck:Value4
+   fun:*
+   fun:*
+   fun:AT_collect
+}
+
+{
+   ATerm library conservatively scans for GC roots
+   Memcheck:Value8
+   fun:*
+   fun:*
+   fun:AT_collect
+}
+
+{
+   ATerm library conservatively scans for GC roots
+   Memcheck:Cond
+   fun:*
+   fun:*
+   fun:AT_collect
 }

configure.ac

@@ -1,11 +1,11 @@
-AC_INIT(nix, 0.11)
+AC_INIT(nix, 0.12)
 AC_CONFIG_SRCDIR(README)
 AC_CONFIG_AUX_DIR(config)
 AM_INIT_AUTOMAKE([dist-bzip2 foreign])
-        
+
 # Change to `1' to produce a `stable' release (i.e., the `preREVISION'
 # suffix is not added).
-STABLE=0
+STABLE=1
 
 # Put the revision number in the version.
 if test "$STABLE" != "1"; then
@@ -16,9 +16,7 @@ if test "$STABLE" != "1"; then
     fi
 fi
 
-AC_DEFINE_UNQUOTED(NIX_VERSION, ["$VERSION"], [version])
-
-AC_PREFIX_DEFAULT(/nix)
+AC_DEFINE_UNQUOTED(NIX_VERSION, ["$VERSION"], [Nix version.])
 
 AC_CANONICAL_HOST
 
@@ -54,13 +52,17 @@ case $sys_name in
 esac
 
 AC_ARG_WITH(system, AC_HELP_STRING([--with-system=SYSTEM],
-  [platform identifier (e.g., `i686-linux')]),
+  [Platform identifier (e.g., `i686-linux').]),
   system=$withval, system="${machine_name}-${sys_name}")
 AC_MSG_RESULT($system)
 AC_SUBST(system)
 AC_DEFINE_UNQUOTED(SYSTEM, ["$system"], [platform identifier (`cpu-os')])
 
 
+# State should be stored in /nix/var, unless the user overrides it explicitly.
+test "$localstatedir" = '${prefix}/var' && localstatedir=/nix/var
+
+
 # Windows-specific stuff.
 if test "$sys_name" = "cygwin"; then
     # We cannot delete open files.
@@ -94,14 +96,24 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <iostream>
 using namespace std;
 static char buf[1024];]],
     [[cerr.rdbuf()->pubsetbuf(buf, sizeof(buf));]])],
-    [AC_MSG_RESULT(yes) AC_DEFINE(HAVE_PUBSETBUF, 1, [whether pubsetbuf is available])],
+    [AC_MSG_RESULT(yes) AC_DEFINE(HAVE_PUBSETBUF, 1, [Whether pubsetbuf is available.])],
     AC_MSG_RESULT(no))
 AC_LANG_POP(C++)
 
 
+# Check for chroot support (requires chroot() and bind mounts).
+AC_CHECK_FUNCS([chroot])
+AC_CHECK_HEADERS([sys/param.h], [], [], [])
+AC_CHECK_HEADERS([sys/mount.h], [], [],
+[#ifdef HAVE_SYS_PARAM_H
+# include <sys/param.h>
+# endif
+])
+
+
 # Check for <locale>
 AC_LANG_PUSH(C++)
-AC_CHECK_HEADERS([locale])
+AC_CHECK_HEADERS([locale], [], [], [])
 AC_LANG_POP(C++)
 
 
@@ -114,7 +126,7 @@ fi
 ])
 
 NEED_PROG(curl, curl)
-NEED_PROG(shell, sh)
+NEED_PROG(bash, bash)
 NEED_PROG(patch, patch)
 AC_PATH_PROG(xmllint, xmllint, false)
 AC_PATH_PROG(xsltproc, xsltproc, false)
@@ -125,6 +137,8 @@ AC_PATH_PROG(bison, bison, false)
 NEED_PROG(perl, perl)
 NEED_PROG(tar, tar)
 AC_PATH_PROG(dot, dot)
+AC_PATH_PROG(dblatex, dblatex)
+AC_PATH_PROG(gzip, gzip)
 
 AC_PATH_PROG(openssl_prog, openssl, openssl) # if not found, call openssl in $PATH
 AC_SUBST(openssl_prog)
@@ -162,11 +176,16 @@ AC_SUBST(xmlflags)
 
 AC_ARG_WITH(store-dir, AC_HELP_STRING([--with-store-dir=PATH],
   [path of the Nix store]),
-  storedir=$withval, storedir='${prefix}/store')
+  storedir=$withval, storedir='/nix/store')
 AC_SUBST(storedir)
 
+AC_ARG_ENABLE(old-db-compat, AC_HELP_STRING([--disable-old-db-compat],
+  [disable support for converting from old Berkeley DB-based Nix stores]),
+  old_db_compat=$enableval, old_db_compat=yes)
+AM_CONDITIONAL(OLD_DB_COMPAT, test "$old_db_compat" = "yes")
+
 AC_ARG_WITH(bdb, AC_HELP_STRING([--with-bdb=PATH],
-  [prefix of Berkeley DB]),
+  [prefix of Berkeley DB (for Nix <= 0.11 compatibility)]),
   bdb=$withval, bdb=)
 AM_CONDITIONAL(HAVE_BDB, test -n "$bdb")
 if test -z "$bdb"; then
@@ -176,6 +195,12 @@ else
   bdb_lib="-L$bdb/lib -ldb_cxx"
   bdb_include="-I$bdb/include"
 fi
+if test "$old_db_compat" = "no"; then
+  bdb_lib=
+  bdb_include=
+else
+  AC_DEFINE(OLD_DB_COMPAT, 1, [Whether to support converting from old Berkeley DB-based Nix stores.])
+fi
 AC_SUBST(bdb_lib)
 AC_SUBST(bdb_include)
 
@@ -204,7 +229,7 @@ if test -n "$openssl"; then
   LDFLAGS="-L$openssl/lib -lcrypto $LDFLAGS"
   CFLAGS="-I$openssl/include $CFLAGS"
   CXXFLAGS="-I$openssl/include $CXXFLAGS"
-  AC_DEFINE(HAVE_OPENSSL, 1, [whether to use OpenSSL])
+  AC_DEFINE(HAVE_OPENSSL, 1, [Whether to use OpenSSL.])
 fi
 
 AC_ARG_WITH(bzip2, AC_HELP_STRING([--with-bzip2=PATH],
@@ -217,7 +242,7 @@ if test -z "$bzip2"; then
   bzip2_lib='-L${top_builddir}/externals/inst-bzip2/lib -lbz2'
   bzip2_include='-I${top_builddir}/externals/inst-bzip2/include'
   # The binary will be copied to $libexecdir.
-  bzip2_bin='${libexecdir}'
+  bzip2_bin='${libexecdir}/nix'
   # But for testing, we have to use the temporary copy :-(
   bzip2_bin_test='${top_builddir}/externals/inst-bzip2/bin'
 else
@@ -245,6 +270,10 @@ AM_CONDITIONAL(INIT_STATE, test "$init_state" = "yes")
 AC_CHECK_FUNCS([setresuid setreuid lchown])
 
 
+# Nice to have, but not essential.
+AC_CHECK_FUNCS([strsignal])
+
+
 # This is needed if ATerm, Berkeley DB or bzip2 are static libraries,
 # and the Nix libraries are dynamic.
 if test "$(uname)" = "Darwin"; then

doc/manual/Makefile.am

@@ -14,15 +14,16 @@ XSLTPROC = $(xsltproc) $(xmlflags) \
 man1_MANS = nix-env.1 nix-build.1 nix-store.1 nix-instantiate.1 \
  nix-collect-garbage.1 nix-push.1 nix-pull.1 \
  nix-prefetch-url.1 nix-channel.1 \
- nix-pack-closure.1 nix-unpack-closure.1 \
  nix-install-package.1 nix-hash.1 nix-copy-closure.1
 
+man8_MANS = nix-worker.8
+
 FIGURES = figures/user-environments.png
 
 MANUAL_SRCS = manual.xml introduction.xml installation.xml \
- package-management.xml writing-nix-expressions.xml \
+ package-management.xml writing-nix-expressions.xml builtins.xml \
  build-farm.xml \
- $(man1_MANS:.1=.xml) \
+ $(man1_MANS:.1=.xml) $(man8_MANS:.8=.xml) \
  troubleshooting.xml bugs.xml opt-common.xml opt-common-syn.xml \
  env-common.xml quick-start.xml nix-lang-ref.xml glossary.xml \
  conf-file.xml release-notes.xml \
@@ -47,6 +48,14 @@ manual.html: $(MANUAL_SRCS) manual.is-valid images
 	$(XSLTPROC) --nonet --xinclude --output manual.html \
 	  $(docbookxsl)/html/docbook.xsl manual.xml
 
+manual.pdf: $(MANUAL_SRCS) manual.is-valid images
+	if test "$(dblatex)" != ""; then \
+		$(dblatex) manual.xml; \
+	else \
+		echo "Please install dblatex and rerun configure."; \
+		exit 1; \
+	fi
+
 
 NEWS_OPTS = \
  --stringparam generate.toc "article nop" \
@@ -68,12 +77,12 @@ NEWS.txt: release-notes.xml
 all-local: manual.html NEWS.html NEWS.txt
 
 install-data-local: manual.html
-	$(INSTALL) -d $(DESTDIR)$(datadir)/nix/manual
-	$(INSTALL_DATA) manual.html $(DESTDIR)$(datadir)/nix/manual
-	$(INSTALL_DATA) style.css $(DESTDIR)$(datadir)/nix/manual
-	cp -r images $(DESTDIR)$(datadir)/nix/manual/images
-	$(INSTALL) -d $(DESTDIR)$(datadir)/nix/manual/figures
-	$(INSTALL_DATA) $(FIGURES) $(DESTDIR)$(datadir)/nix/manual/figures
+	$(INSTALL) -d $(DESTDIR)$(docdir)/manual
+	$(INSTALL_DATA) manual.html $(DESTDIR)$(docdir)/manual
+	$(INSTALL_DATA) style.css $(DESTDIR)$(docdir)/manual
+	cp -r images $(DESTDIR)$(docdir)/manual/images
+	$(INSTALL) -d $(DESTDIR)$(docdir)/manual/figures
+	$(INSTALL_DATA) $(FIGURES) $(DESTDIR)$(docdir)/manual/figures
 
 images:
 	mkdir images

doc/manual/build-farm.xml

@@ -36,10 +36,10 @@ build farm, since:
   builds, and Nix expressions are self-contained.</para></listitem>
 
   <listitem><para>Nix will only rebuild things that have actually
-  changed.  For instance, if the sources of a component haven't
-  changed between runs of the build farm, the component won't be
-  rebuild (unless it was garbage-collected).  Also, dependencies
-  typically don't change very often, so they only need to be built
+  changed.  For instance, if the sources of a package haven't changed
+  between runs of the build farm, the package won't be rebuilt (unless
+  it was garbage-collected).  Also, dependencies typically don't
+  change very often, so they only need to be built
   once.</para></listitem>
 
   <listitem><para>The results of a Nix build farm can be made
@@ -56,7 +56,7 @@ build farm, since:
 <para>TODO</para>
 
 <para>The sources of the Nix build farm are at <link
-xlink:href='https://svn.cs.uu.nl:12443/repos/trace/release/trunk'/>.</para>
+xlink:href='https://svn.nixos.org/repos/nix/release/trunk'/>.</para>
 
 </section>
 
@@ -85,7 +85,7 @@ nix@scratchy.labs.cs.uu.nl  i686-linux      /home/nix/.ssh/id_scratchy_auto
 
 <para>An example build hook can be found in the Nix build farm
 sources: <link
-xlink:href='https://svn.cs.uu.nl:12443/repos/trace/release/trunk/common/distributed/build-remote.pl'
+xlink:href='https://svn.nixos.org/repos/nix/release/trunk/common/distributed/build-remote.pl'
 />.  It should be suitable for most purposes, with maybe some minor
 adjustments.  It uses <command>ssh</command> and
 <command>rsync</command> to copy the build inputs and outputs and

doc/manual/builtins.xml

@@ -0,0 +1,821 @@
+<section xmlns="http://docbook.org/ns/docbook"
+         xmlns:xlink="http://www.w3.org/1999/xlink"
+         xml:id='ssec-builtins'>
+
+<title>Built-in functions</title>
+
+
+<para>This section lists the functions and constants built into the
+Nix expression evaluator.  (The built-in function
+<function>derivation</function> is discussed above.)  Some built-ins,
+such as <function>derivation</function>, are always in scope of every
+Nix expression; you can just access them right away.  But to prevent
+polluting the namespace too much, most built-ins are not in scope.
+Instead, you can access them through the <varname>builtins</varname>
+built-in value, which is an attribute set that contains all built-in
+functions and values.  For instance, <function>derivation</function>
+is also available as <function>builtins.derivation</function>.</para>
+
+
+<variablelist>
+
+  
+  <varlistentry><term><function>abort</function> <replaceable>s</replaceable></term>
+
+    <listitem><para>Abort Nix expression evaluation, print error
+    message <replaceable>s</replaceable>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.add</function>
+  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>
+
+    <listitem><para>Return the sum of the integers
+    <replaceable>e1</replaceable> and
+    <replaceable>e2</replaceable>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.attrNames</function>
+  <replaceable>attrs</replaceable></term>
+
+    <listitem><para>Return the names of the attributes in the
+    attribute set <replaceable>attrs</replaceable> in a sorted list.
+    For instance, <literal>builtins.attrNames {y = 1; x =
+    "foo";}</literal> evaluates to <literal>["x" "y"]</literal>.
+    There is no built-in function <function>attrValues</function>, but
+    you can easily define it yourself:
+
+<programlisting>
+attrValues = attrs: map (name: builtins.getAttr name attrs) (builtins.attrNames attrs);</programlisting>
+
+    </para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>baseNameOf</function> <replaceable>s</replaceable></term>
+
+    <listitem><para>Return the <emphasis>base name</emphasis> of the
+    string <replaceable>s</replaceable>, that is, everything following
+    the final slash in the string.  This is similar to the GNU
+    <command>basename</command> command.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><varname>builtins</varname></term>
+
+    <listitem><para>The attribute set <varname>builtins</varname>
+    contains all the built-in functions and values.  You can use
+    <varname>builtins</varname> to test for the availability of
+    features in the Nix installation, e.g.,
+
+<programlisting>
+if builtins ? getEnv then builtins.getEnv "PATH" else ""</programlisting>
+
+    This allows a Nix expression to fall back gracefully on older Nix
+    installations that don’t have the desired built-in function.
+    However, in that case you should not write
+
+<programlisting>
+if builtins ? getEnv then __getEnv "PATH" else ""</programlisting>
+
+    This Nix expression will trigger an “undefined variable” error on
+    older Nix versions since <function>__getEnv</function> doesn’t
+    exist.  <literal>builtins.getEnv</literal>, on the other hand, is
+    safe since <literal>builtins</literal> always exists and attribute
+    selection is lazy, so it’s only performed if the test
+    succeeds.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.compareVersions</function>
+  <replaceable>s1</replaceable> <replaceable>s2</replaceable></term>
+
+    <listitem><para>Compare two strings representing versions and
+    return <literal>-1</literal> if version
+    <replaceable>s1</replaceable> is older than version
+    <replaceable>s2</replaceable>, <literal>0</literal> if they are
+    the same, and <literal>1</literal> if
+    <replaceable>s1</replaceable> is newer than
+    <replaceable>s2</replaceable>.  The version comparison algorithm
+    is the same as the one used by <link
+    linkend="ssec-version-comparisons"><command>nix-env
+    -u</command></link>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry
+  xml:id='builtin-currentSystem'><term><varname>builtins.currentSystem</varname></term>
+
+    <listitem><para>The built-in value <varname>currentSystem</varname>
+    evaluates to the Nix platform identifier for the Nix installation
+    on which the expression is being evaluated, such as
+    <literal>"i686-linux"</literal> or
+    <literal>"powerpc-darwin"</literal>.</para></listitem>
+
+  </varlistentry>
+
+
+  <!--
+  <varlistentry><term><function>currentTime</function></term>
+
+    <listitem><para>The built-in value <varname>currentTime</varname>
+    returns the current system time in seconds since 00:00:00 1/1/1970
+    UTC.  Due to the evaluation model of Nix expressions
+    (<emphasis>maximal laziness</emphasis>), it always yields the same
+    value within an execution of Nix.</para></listitem>
+
+  </varlistentry>
+  -->
+
+  
+  <!--
+  <varlistentry><term><function>dependencyClosure</function></term>
+
+    <listitem><para>TODO</para></listitem>
+
+  </varlistentry>
+  -->
+
+  
+  <varlistentry><term><function>derivation</function>
+  <replaceable>attrs</replaceable></term>
+
+    <listitem><para><function>derivation</function> is described in
+    <xref linkend='ssec-derivation' />.</para></listitem>
+
+  </varlistentry>
+
+
+  <varlistentry><term><function>dirOf</function> <replaceable>s</replaceable></term>
+
+    <listitem><para>Return the directory part of the string
+    <replaceable>s</replaceable>, that is, everything before the final
+    slash in the string.  This is similar to the GNU
+    <command>dirname</command> command.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.div</function>
+  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>
+
+    <listitem><para>Return the quotient of the integers
+    <replaceable>e1</replaceable> and
+    <replaceable>e2</replaceable>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.filterSource</function>
+  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>
+
+    <listitem>
+
+      <para>This function allows you to copy sources into the Nix
+      store while filtering certain files.  For instance, suppose that
+      you want to use the directory <filename>source-dir</filename> as
+      an input to a Nix expression, e.g.
+
+<programlisting>
+stdenv.mkDerivation {
+  ...
+  src = ./source-dir;
+}
+</programlisting>
+
+      However, if <filename>source-dir</filename> is a Subversion
+      working copy, then all those annoying <filename>.svn</filename>
+      subdirectories will also be copied to the store.  Worse, the
+      contents of those directories may change a lot, causing lots of
+      spurious rebuilds.  With <function>filterSource</function> you
+      can filter out the <filename>.svn</filename> directories:
+
+<programlisting>
+  src = builtins.filterSource
+    (path: type: type != "directory" || baseNameOf path != ".svn")
+    ./source-dir;
+</programlisting>
+
+      </para>
+
+      <para>Thus, the first argument <replaceable>e1</replaceable>
+      must be a predicate function that is called for each regular
+      file, directory or symlink in the source tree
+      <replaceable>e2</replaceable>.  If the function returns
+      <literal>true</literal>, the file is copied to the Nix store,
+      otherwise it is omitted.  The function is called with two
+      arguments.  The first is the full path of the file.  The second
+      is a string that identifies the type of the file, which is
+      either <literal>"regular"</literal>,
+      <literal>"directory"</literal>, <literal>"symlink"</literal> or
+      <literal>"unknown"</literal> (for other kinds of files such as
+      device nodes or fifos — but note that those cannot be copied to
+      the Nix store, so if the predicate returns
+      <literal>true</literal> for them, the copy will fail).</para>
+
+    </listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.getAttr</function>
+  <replaceable>s</replaceable> <replaceable>attrs</replaceable></term>
+
+    <listitem><para><function>getAttr</function> returns the attribute
+    named <replaceable>s</replaceable> from the attribute set
+    <replaceable>attrs</replaceable>.  Evaluation aborts if the
+    attribute doesn’t exist.  This is a dynamic version of the
+    <literal>.</literal> operator, since <replaceable>s</replaceable>
+    is an expression rather than an identifier.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.getEnv</function>
+  <replaceable>s</replaceable></term>
+
+    <listitem><para><function>getEnv</function> returns the value of
+    the environment variable <replaceable>s</replaceable>, or an empty
+    string if the variable doesn’t exist.  This function should be
+    used with care, as it can introduce all sorts of nasty environment
+    dependencies in your Nix expression.</para>
+
+    <para><function>getEnv</function> is used in Nix Packages to
+    locate the file <filename>~/.nixpkgs/config.nix</filename>, which
+    contains user-local settings for Nix Packages.  (That is, it does
+    a <literal>getEnv "HOME"</literal> to locate the user’s home
+    directory.)</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.hasAttr</function>
+  <replaceable>s</replaceable> <replaceable>attrs</replaceable></term>
+
+    <listitem><para><function>hasAttr</function> returns
+    <literal>true</literal> if the attribute set
+    <replaceable>attrs</replaceable> has an attribute named
+    <replaceable>s</replaceable>, and <literal>false</literal>
+    otherwise.  This is a dynamic version of the <literal>?</literal>
+    operator, since <replaceable>s</replaceable> is an expression
+    rather than an identifier.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.head</function>
+  <replaceable>list</replaceable></term>
+
+    <listitem><para>Return the first element of a list; abort
+    evaluation if the argument isn’t a list or is an empty list.  You
+    can test whether a list is empty by comparing it with
+    <literal>[]</literal>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>import</function>
+  <replaceable>path</replaceable></term>
+
+    <listitem><para>Load, parse and return the Nix expression in the
+    file <replaceable>path</replaceable>.  Evaluation aborts if the
+    file doesn’t exist or contains an incorrect Nix
+    expression.  <function>import</function> implements Nix’s module
+    system: you can put any Nix expression (such as an attribute set
+    or a function) in a separate file, and use it from Nix expressions
+    in other files.</para>
+
+    <para>A Nix expression loaded by <function>import</function> must
+    not contain any <emphasis>free variables</emphasis> (identifiers
+    that are not defined in the Nix expression itself and are not
+    built-in).  Therefore, it cannot refer to variables that are in
+    scope at the call site.  For instance, if you have a calling
+    expression
+    
+<programlisting>
+rec {
+  x = 123;
+  y = import ./foo.nix;
+}</programlisting>
+
+    then the following <filename>foo.nix</filename> will give an
+    error:
+
+<programlisting>
+x + 456</programlisting>
+
+    since <varname>x</varname> is not in scope in
+    <filename>foo.nix</filename>.  If you want <varname>x</varname>
+    to be available in <filename>foo.nix</filename>, you should pass
+    it as a function argument:
+
+<programlisting>
+rec {
+  x = 123;
+  y = import ./foo.nix x;
+}</programlisting>
+
+    and
+
+<programlisting>
+x: x + 456</programlisting>
+
+    (The function argument doesn’t have to be called
+    <varname>x</varname> in <filename>foo.nix</filename>; any name
+    would work.)</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.isAttrs</function>
+  <replaceable>e</replaceable></term>
+
+    <listitem><para>Return <literal>true</literal> if
+    <replaceable>e</replaceable> evaluates to an attribute set, and
+    <literal>false</literal> otherwise.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.isList</function>
+  <replaceable>e</replaceable></term>
+
+    <listitem><para>Return <literal>true</literal> if
+    <replaceable>e</replaceable> evaluates to a list, and
+    <literal>false</literal> otherwise.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.isFunction</function>
+  <replaceable>e</replaceable></term>
+
+    <listitem><para>Return <literal>true</literal> if
+    <replaceable>e</replaceable> evaluates to a function, and
+    <literal>false</literal> otherwise.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>isNull</function>
+  <replaceable>e</replaceable></term>
+
+    <listitem><para>Return <literal>true</literal> if
+    <replaceable>e</replaceable> evaluates to <literal>null</literal>,
+    and <literal>false</literal> otherwise.</para>
+
+    <warning><para>This function is <emphasis>deprecated</emphasis>;
+    just write <literal>e == null</literal> instead.</para></warning>
+    
+    </listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.length</function>
+  <replaceable>e</replaceable></term>
+
+    <listitem><para>Return the length of the list
+    <replaceable>e</replaceable>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.lessThan</function>
+  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>
+
+    <listitem><para>Return <literal>true</literal> if the integer
+    <replaceable>e1</replaceable> is less than the integer
+    <replaceable>e2</replaceable>, and <literal>false</literal>
+    otherwise.  Evaluation aborts if either
+    <replaceable>e1</replaceable> or <replaceable>e2</replaceable>
+    does not evaluate to an integer.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.listToAttrs</function>
+  <replaceable>e</replaceable></term>
+
+    <listitem><para>Construct an attribute set from a list specifying
+    the names and values of each attribute.  Each element of the list
+    should be an attribute set consisting of a string-valued attribute
+    <varname>name</varname> specifying the name of the attribute, and
+    an attribute <varname>value</varname> specifying its value.
+    Example:
+
+<programlisting>
+builtins.listToAttrs [
+  {name = "foo"; value = 123;}
+  {name = "bar"; value = 456;}
+]
+</programlisting>
+
+    evaluates to
+
+<programlisting>
+{ foo = 123; bar = 456; }
+</programlisting>
+
+    </para></listitem>
+
+  </varlistentry>
+  
+  <varlistentry><term><function>map</function>
+  <replaceable>f</replaceable> <replaceable>list</replaceable></term>
+
+    <listitem><para>Apply the function <replaceable>f</replaceable> to
+    each element in the list <replaceable>list</replaceable>.  For
+    example,
+
+<programlisting>
+map (x: "foo" + x) ["bar" "bla" "abc"]</programlisting>
+
+    evaluates to <literal>["foobar" "foobla"
+    "fooabc"]</literal>.</para></listitem>
+    
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.mul</function>
+  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>
+
+    <listitem><para>Return the product of the integers
+    <replaceable>e1</replaceable> and
+    <replaceable>e2</replaceable>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.parseDrvName</function>
+  <replaceable>s</replaceable></term>
+
+    <listitem><para>Split the string <replaceable>s</replaceable> into
+    a package name and version.  The package name is everything up to
+    but not including the first dash followed by a digit, and the
+    version is everything following that dash.  The result is returned
+    in an attribute set <literal>{name, version}</literal>.  Thus,
+    <literal>builtins.parseDrvName "nix-0.12pre12876"</literal>
+    returns <literal>{name = "nix"; version =
+    "0.12pre12876";}</literal>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.pathExists</function>
+  <replaceable>path</replaceable></term>
+
+    <listitem><para>Return <literal>true</literal> if the path
+    <replaceable>path</replaceable> exists, and
+    <literal>false</literal> otherwise.  One application of this
+    function is to conditionally include a Nix expression containing
+    user configuration:
+
+<programlisting>
+let
+  fileName = builtins.getEnv "CONFIG_FILE";
+  config =
+    if fileName != "" &amp;&amp; builtins.pathExists (builtins.toPath fileName)
+    then import (builtins.toPath fileName)
+    else { someSetting = false; }; <lineannotation># default configuration</lineannotation>
+in config.someSetting</programlisting>
+
+    (Note that <envar>CONFIG_FILE</envar> must be an absolute path for
+    this to work.)</para></listitem>
+
+  </varlistentry>
+
+
+  <!--
+  <varlistentry><term><function>relativise</function></term>
+
+    <listitem><para>TODO</para></listitem>
+
+  </varlistentry>
+  -->
+
+  
+  <varlistentry><term><function>builtins.readFile</function>
+  <replaceable>path</replaceable></term>
+
+    <listitem><para>Return the contents of the file
+    <replaceable>path</replaceable> as a string.</para></listitem>
+
+  </varlistentry>
+  
+  
+  <varlistentry><term><function>removeAttrs</function>
+  <replaceable>attrs</replaceable> <replaceable>list</replaceable></term>
+
+    <listitem><para>Remove the attributes listed in
+    <replaceable>list</replaceable> from the attribute set
+    <replaceable>attrs</replaceable>.  The attributes don’t have to
+    exist in <replaceable>attrs</replaceable>. For instance,
+
+<screen>
+removeAttrs { x = 1; y = 2; z = 3; } ["a" "x" "z"]</screen>
+
+    evaluates to <literal>{y = 2;}</literal>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.stringLength</function>
+  <replaceable>e</replaceable></term>
+
+    <listitem><para>Return the length of the string
+    <replaceable>e</replaceable>.  If <replaceable>e</replaceable> is
+    not a string, evaluation is aborted.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.sub</function>
+  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>
+
+    <listitem><para>Return the difference between the integers
+    <replaceable>e1</replaceable> and
+    <replaceable>e2</replaceable>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.substring</function>
+  <replaceable>start</replaceable> <replaceable>len</replaceable>
+  <replaceable>s</replaceable></term>
+
+    <listitem><para>Return the substring of
+    <replaceable>s</replaceable> from character position
+    <replaceable>start</replaceable> (zero-based) up to but not
+    including <replaceable>start + len</replaceable>.  If
+    <replaceable>start</replaceable> is greater than the length of the
+    string, an empty string is returned, and if <replaceable>start +
+    len</replaceable> lies beyond the end of the string, only the
+    substring up to the end of the string is returned.
+    <replaceable>start</replaceable> must be
+    non-negative.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.tail</function>
+  <replaceable>list</replaceable></term>
+
+    <listitem><para>Return the second to last elements of a list;
+    abort evaluation if the argument isn’t a list or is an empty
+    list.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>throw</function>
+  <replaceable>s</replaceable></term>
+
+    <listitem><para>Throw an error message
+    <replaceable>s</replaceable>.  This usually aborts Nix expression
+    evaluation, but in <command>nix-env -qa</command> and other
+    commands that try to evaluate a set of derivations to get
+    information about those derivations, a derivation that throws an
+    error is silently skipped (which is not the case for
+    <function>abort</function>).</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry
+  xml:id='builtin-toFile'><term><function>builtins.toFile</function>
+  <replaceable>name</replaceable> <replaceable>s</replaceable></term>
+
+    <listitem><para>Store the string <replaceable>s</replaceable> in a
+    file in the Nix store and return its path.  The file has suffix
+    <replaceable>name</replaceable>.  This file can be used as an
+    input to derivations.  One application is to write builders
+    “inline”.  For instance, the following Nix expression combines
+    <xref linkend='ex-hello-nix' /> and <xref
+    linkend='ex-hello-builder' /> into one file:
+
+<programlisting>
+{stdenv, fetchurl, perl}:
+
+stdenv.mkDerivation {
+  name = "hello-2.1.1";
+  
+  builder = builtins.toFile "builder.sh" "
+    source $stdenv/setup
+
+    PATH=$perl/bin:$PATH
+
+    tar xvfz $src
+    cd hello-*
+    ./configure --prefix=$out
+    make
+    make install
+  ";
+
+  src = fetchurl {
+    url = http://nix.cs.uu.nl/dist/tarballs/hello-2.1.1.tar.gz;
+    md5 = "70c9ccf9fac07f762c24f2df2290784d";
+  };
+  inherit perl;
+}</programlisting>
+  
+    </para>
+
+    <para>It is even possible for one file to refer to another, e.g.,
+
+<programlisting>
+  builder = let
+    configFile = builtins.toFile "foo.conf" "
+      # This is some dummy configuration file.
+      <replaceable>...</replaceable>
+    ";
+  in builtins.toFile "builder.sh" "
+    source $stdenv/setup
+    <replaceable>...</replaceable>
+    cp ${configFile} $out/etc/foo.conf
+  ";</programlisting>
+
+    Note that <literal>${configFile}</literal> is an antiquotation
+    (see <xref linkend='ssec-values' />), so the result of the
+    expression <literal>configFile</literal> (i.e., a path like
+    <filename>/nix/store/m7p7jfny445k...-foo.conf</filename>) will be
+    spliced into the resulting string.</para>
+
+    <para>It is however <emphasis>not</emphasis> allowed to have files
+    mutually referring to each other, like so:
+
+<programlisting>
+let
+  foo = builtins.toFile "foo" "...${bar}...";
+  bar = builtins.toFile "bar" "...${foo}...";
+in foo</programlisting>
+
+    This is not allowed because it would cause a cyclic dependency in
+    the computation of the cryptographic hashes for
+    <varname>foo</varname> and <varname>bar</varname>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.toPath</function> <replaceable>s</replaceable></term>
+
+    <listitem><para>Convert the string value
+    <replaceable>s</replaceable> into a path value.  The string
+    <replaceable>s</replaceable> must represent an absolute path
+    (i.e., must start with <literal>/</literal>).  The path need not
+    exist.  The resulting path is canonicalised, e.g.,
+    <literal>builtins.toPath "//foo/xyzzy/../bar/"</literal> returns
+    <literal>/foo/bar</literal>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>toString</function> <replaceable>e</replaceable></term>
+
+    <listitem><para>Convert the expression
+    <replaceable>e</replaceable> to a string.
+    <replaceable>e</replaceable> can be a string (in which case
+    <function>toString</function> is a no-op) or a path (e.g.,
+    <literal>toString /foo/bar</literal> yields
+    <literal>"/foo/bar"</literal>.</para></listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry xml:id='builtin-toXML'><term><function>builtins.toXML</function> <replaceable>e</replaceable></term>
+
+    <listitem><para>Return a string containing an XML representation
+    of <replaceable>e</replaceable>.  The main application for
+    <function>toXML</function> is to communicate information with the
+    builder in a more structured format than plain environment
+    variables.</para>
+
+    <!-- TODO: more formally describe the schema of the XML
+    representation -->
+
+    <para><xref linkend='ex-toxml' /> shows an example where this is
+    the case.  The builder is supposed to generate the configuration
+    file for a <link xlink:href='http://jetty.mortbay.org/'>Jetty
+    servlet container</link>.  A servlet container contains a number
+    of servlets (<filename>*.war</filename> files) each exported under
+    a specific URI prefix.  So the servlet configuration is a list of
+    attribute sets containing the <varname>path</varname> and
+    <varname>war</varname> of the servlet (<xref
+    linkend='ex-toxml-co-servlets' />).  This kind of information is
+    difficult to communicate with the normal method of passing
+    information through an environment variable, which just
+    concatenates everything together into a string (which might just
+    work in this case, but wouldn’t work if fields are optional or
+    contain lists themselves).  Instead the Nix expression is
+    converted to an XML representation with
+    <function>toXML</function>, which is unambiguous and can easily be
+    processed with the appropriate tools.  For instance, in the
+    example an XSLT stylesheet (<xref linkend='ex-toxml-co-stylesheet'
+    />) is applied to it (<xref linkend='ex-toxml-co-apply' />) to
+    generate the XML configuration file for the Jetty server.  The XML
+    representation produced from <xref linkend='ex-toxml-co-servlets'
+    /> by <function>toXML</function> is shown in <xref
+    linkend='ex-toxml-result' />.</para>
+
+    <para>Note that <xref linkend='ex-toxml' /> uses the <function
+    linkend='builtin-toFile'>toFile</function> built-in to write the
+    builder and the stylesheet “inline” in the Nix expression.  The
+    path of the stylesheet is spliced into the builder at
+    <literal>xsltproc ${stylesheet}
+    <replaceable>...</replaceable></literal>.</para>
+
+    <example xml:id='ex-toxml'><title>Passing information to a builder
+    using <function>toXML</function></title>
+    
+<programlisting><![CDATA[
+{stdenv, fetchurl, libxslt, jira, uberwiki}:
+
+stdenv.mkDerivation (rec {
+  name = "web-server";
+
+  buildInputs = [libxslt];
+  
+  builder = builtins.toFile "builder.sh" "
+    source $stdenv/setup
+    mkdir $out
+    echo $servlets | xsltproc ${stylesheet} - > $out/server-conf.xml]]> <co xml:id='ex-toxml-co-apply' /> <![CDATA[
+  ";
+
+  stylesheet = builtins.toFile "stylesheet.xsl"]]> <co xml:id='ex-toxml-co-stylesheet' /> <![CDATA[
+   "<?xml version='1.0' encoding='UTF-8'?>
+    <xsl:stylesheet xmlns:xsl='http://www.w3.org/1999/XSL/Transform' version='1.0'>
+      <xsl:template match='/'>
+        <Configure>
+          <xsl:for-each select='/expr/list/attrs'>
+            <Call name='addWebApplication'>
+              <Arg><xsl:value-of select=\"attr[@name = 'path']/string/@value\" /></Arg>
+              <Arg><xsl:value-of select=\"attr[@name = 'war']/path/@value\" /></Arg>
+            </Call>
+          </xsl:for-each>
+        </Configure>
+      </xsl:template>
+    </xsl:stylesheet>
+  ";
+
+  servlets = builtins.toXML []]> <co xml:id='ex-toxml-co-servlets' /> <![CDATA[
+    { path = "/bugtracker"; war = jira + "/lib/atlassian-jira.war"; }
+    { path = "/wiki"; war = uberwiki + "/uberwiki.war"; }
+  ];
+})]]></programlisting>
+
+    </example>
+
+    <example xml:id='ex-toxml-result'><title>XML representation produced by
+    <function>toXML</function></title>
+    
+<programlisting><![CDATA[<?xml version='1.0' encoding='utf-8'?>
+<expr>
+  <list>
+    <attrs>
+      <attr name="path">
+        <string value="/bugtracker" />
+      </attr>
+      <attr name="war">
+        <path value="/nix/store/d1jh9pasa7k2...-jira/lib/atlassian-jira.war" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="path">
+        <string value="/wiki" />
+      </attr>
+      <attr name="war">
+        <path value="/nix/store/y6423b1yi4sx...-uberwiki/uberwiki.war" />
+      </attr>
+    </attrs>
+  </list>
+</expr>]]></programlisting>
+
+    </example>
+
+    </listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry><term><function>builtins.trace</function>
+  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>
+
+    <listitem><para>Evaluate <replaceable>e1</replaceable> and print its
+    abstract syntax representation on standard error.  Then return
+    <replaceable>e2</replaceable>.  This function is useful for
+    debugging.</para></listitem>
+
+  </varlistentry>
+
+  
+</variablelist>
+
+
+</section>

doc/manual/conf-file.xml

@@ -60,27 +60,6 @@ env-keep-derivations = false
   </varlistentry>
 
   
-  <varlistentry xml:id="conf-gc-reserved-space"><term><literal>gc-reserved-space</literal></term>
-
-    <listitem><para>This option specifies how much space should be
-    reserved in normal use so that the garbage collector can run
-    succesfully.  Since the garbage collector must perform Berkeley DB
-    transactions, it needs some disk space for itself.  However, when
-    the disk is full, this space is not available, so the collector
-    would not be able to run precisely when it is most needed.</para>
-
-    <para>For this reason, when Nix is run, it allocates a file
-    <filename>/nix/var/nix/db/reserved</filename> of the size
-    specified by this option.  When the garbage collector is run, this
-    file is deleted before the Berkeley DB environment is opened.
-    This should give it enough room to proceed.</para>
-
-    <para>The default is <literal>1048576</literal> (1
-    MiB).</para></listitem>
-
-  </varlistentry>
-
-  
   <varlistentry><term><literal>env-keep-derivations</literal></term>
 
     <listitem><para>If <literal>false</literal> (default), derivations
@@ -118,6 +97,123 @@ env-keep-derivations = false
   </varlistentry>
 
 
+  <varlistentry xml:id="conf-build-max-silent-time"><term><literal>build-max-silent-time</literal></term>
+
+    <listitem>
+
+      <para>This option defines the maximum number of seconds that a
+      builder can go without producing any data on standard output or
+      standard error.  This is useful (for instance in a automated
+      build system) to catch builds that are stuck in an infinite
+      loop, or to catch remote builds that are hanging due to network
+      problems.  It can be overriden using the <option
+      linkend="opt-max-silent-time">--max-silent-time</option> command
+      line switch.</para>
+
+      <para>The value <literal>0</literal> means that there is no
+      timeout.  This is also the default.</para>
+
+    </listitem>
+
+  </varlistentry>
+
+
+  <varlistentry xml:id="conf-build-users-group"><term><literal>build-users-group</literal></term>
+
+    <listitem><para>This options specifies the Unix group containing
+    the Nix build user accounts.  In multi-user Nix installations,
+    builds should not be performed by the Nix account since that would
+    allow users to arbitrarily modify the Nix store and database by
+    supplying specially crafted builders; and they cannot be performed
+    by the calling user since that would allow him/her to influence
+    the build result.</para>
+
+    <para>Therefore, if this option is non-empty and specifies a valid
+    group, builds will be performed under the user accounts that are a
+    member of the group specified here (as listed in
+    <filename>/etc/group</filename>).  Those user accounts should not
+    be used for any other purpose!</para>
+
+    <para>Nix will never run two builds under the same user account at
+    the same time.  This is to prevent an obvious security hole: a
+    malicious user writing a Nix expression that modifies the build
+    result of a legitimate Nix expression being built by another user.
+    Therefore it is good to have as many Nix build user accounts as
+    you can spare.  (Remember: uids are cheap.)</para>
+
+    <para>The build users should have permission to create files in
+    the Nix store, but not delete them.  Therefore,
+    <filename>/nix/store</filename> should be owned by the Nix
+    account, its group should be the group specified here, and its
+    mode should be <literal>1775</literal>.</para>
+
+    <para>If the build users group is empty, builds will be performed
+    under the uid of the Nix process (that is, the uid of the caller
+    if <envar>NIX_REMOTE</envar> is empty, the uid under which the Nix
+    daemon runs if <envar>NIX_REMOTE</envar> is
+    <literal>daemon</literal>, or the uid that owns the setuid
+    <command>nix-worker</command> program if <envar>NIX_REMOTE</envar>
+    is <literal>slave</literal>).  Obviously, this should not be used
+    in multi-user settings with untrusted users.</para>
+
+    </listitem>
+
+  </varlistentry>
+
+
+  <varlistentry><term><literal>build-use-chroot</literal></term>
+
+    <listitem><para>If set to <literal>true</literal>, builds will be
+    performed in a <emphasis>chroot environment</emphasis>, i.e., the
+    build will be isolated from the normal file system hierarchy and
+    will only see the Nix store, the temporary build directory, and
+    the directories configured with the <link
+    linkend='conf-build-chroot-dirs'><literal>build-chroot-dirs</literal>
+    option</link> (such as <filename>/proc</filename> and
+    <filename>/dev</filename>).  This is useful to prevent undeclared
+    dependencies on files in directories such as
+    <filename>/usr/bin</filename>.</para>
+
+    <para>The use of a chroot requires that Nix is run as root (but
+    you can still use the <link
+    linkend='conf-build-users-group'>“build users” feature</link> to
+    perform builds under different users than root).  Currently,
+    chroot builds only work on Linux because Nix uses “bind mounts” to
+    make the Nix store and other directories available inside the
+    chroot.</para>
+
+    </listitem>
+
+  </varlistentry>
+
+  
+  <varlistentry xml:id="conf-build-chroot-dirs"><term><literal>build-chroot-dirs</literal></term>
+
+    <listitem><para>When builds are performed in a chroot environment,
+    Nix will mount (using <command>mount --bind</command> on Linux)
+    some directories from the normal file system hierarchy inside the
+    chroot.  These are the Nix store, the temporary build directory
+    (usually
+    <filename>/tmp/nix-<replaceable>pid</replaceable>-<replaceable>number</replaceable></filename>)
+    and the directories listed here.  The default is <literal>dev
+    /proc</literal>.  Files in <filename>/dev</filename> (such as
+    <filename>/dev/null</filename>) are needed by many builds, and
+    some files in <filename>/proc</filename> may also be needed
+    occasionally.</para>
+
+    <para>The value used on NixOS is
+    
+<programlisting>
+build-use-chroot = /dev /proc /bin</programlisting>
+
+    to make the <filename>/bin/sh</filename> symlink available (which
+    is still needed by many builders).</para>
+
+    </listitem>
+
+  </varlistentry>
+
+  
   <varlistentry><term><literal>system</literal></term>
 
     <listitem><para>This option specifies the canonical Nix system

doc/manual/env-common.xml

@@ -263,6 +263,38 @@ $ mount -o bind /mnt/otherdisk/nix /nix</screen>
 </varlistentry>
 
 
+<varlistentry xml:id="envar-remote"><term><envar>NIX_REMOTE</envar></term>
+
+  <listitem><para>This variable should be set to
+  <literal>daemon</literal> if you want to use the Nix daemon to
+  executed Nix operations, which is necessary in <link
+  linkend="ssec-multi-user">multi-user Nix installations</link>.
+  Otherwise, it should be left unset.</para></listitem>
+
+</varlistentry>
+
+    
+<varlistentry xml:id="envar-other-stores"><term><envar>NIX_OTHER_STORES</envar></term>
+
+  <listitem><para>This variable contains the paths of remote Nix
+  installations from whichs paths can be copied, separated by colons.
+  See <xref linkend="sec-sharing-packages" /> for details.  Each path
+  should be the <filename>/nix</filename> directory of a remote Nix
+  installation (i.e., not the <filename>/nix/store</filename>
+  directory).  The paths are subject to globbing, so you can set it so
+  something like <literal>/var/run/nix/remote-stores/*/nix</literal>
+  and mount multiple remote filesystems in
+  <literal>/var/run/nix/remote-stores</literal>.</para>
+
+  <para>Note that if you’re building through the <link
+  linkend="sec-nix-worker">Nix daemon</link>, the only setting for
+  this variable that matters is the one that the
+  <command>nix-worker</command> process uses.  So if you want to
+  change it, you have to restart the daemon.</para></listitem>
+
+</varlistentry>
+
+    
 </variablelist>
 
 

doc/manual/glossary.xml

@@ -74,9 +74,9 @@
 
 <glossentry><glossterm>Nix expression</glossterm>
 
-  <glossdef><para>A high-level description of software components and
+  <glossdef><para>A high-level description of software packages and
   compositions thereof.  Deploying software using Nix entails writing
-  Nix expressions for your components.  Nix expressions are translated
+  Nix expressions for your packages.  Nix expressions are translated
   to derivations that are stored in the Nix store.  These derivations
   can then be built.</para></glossdef>
 

doc/manual/installation.xml

@@ -42,26 +42,22 @@ platforms as well.</para>
 <section><title>Obtaining Nix</title>
 
 <para>The easiest way to obtain Nix is to download a <link
-xlink:href="http://www.cs.uu.nl/groups/ST/Trace/Nix">source
-distribution</link>.  RPMs for Red Hat, SuSE, and Fedora Core are also
-available.</para>
+xlink:href="http://nixos.org/">source distribution</link>.  RPMs
+for Red Hat, SuSE, and Fedora Core are also available.</para>
 
 <para>Alternatively, the most recent sources of Nix can be obtained
 from its <link
-xlink:href="https://svn.cs.uu.nl:12443/repos/trace/nix/trunk">Subversion
+xlink:href="https://svn.nixos.org/repos/nix/nix/trunk">Subversion
 repository</link>.  For example, the following command will check out
 the latest revision into a directory called
 <filename>nix</filename>:</para>
 
 <screen>
-$ svn checkout https://svn.cs.uu.nl:12443/repos/trace/nix/trunk nix</screen>
+$ svn checkout https://svn.nixos.org/repos/nix/nix/trunk nix</screen>
 
 <para>Likewise, specific releases can be obtained from the <link
-xlink:href="https://svn.cs.uu.nl:12443/repos/trace/nix/tags">tags
-directory</link> of the repository.  If you don't have Subversion, you
-can also download an automatically generated <link
-xlink:href="https://svn.cs.uu.nl:12443/dist/trace/">compressed
-tar-file</link> of the head revision of the trunk.</para>
+xlink:href="https://svn.nixos.org/repos/nix/nix/tags">tags
+directory</link> of the repository.</para>
 
 </section>
 
@@ -100,16 +96,23 @@ ubiquitous 2.5.4a won't.  Note that these are only required if you
 modify the parser or when you are building from the Subversion
 repository.</para>
 
-<para>Nix uses Sleepycat's Berkeley DB and CWI's ATerm library.  These
-are included in the Nix source distribution.  If you build from the
-Subversion repository, you must download them yourself and place them
-in the <filename>externals/</filename> directory.  See
+<para>Nix uses CWI's ATerm library and the bzip2 compressor (including
+the bzip2 library).  These are included in the Nix source
+distribution.  If you build from the Subversion repository, you must
+download them yourself and place them in the
+<filename>externals/</filename> directory.  See
 <filename>externals/Makefile.am</filename> for the precise URLs of
 these packages.  Alternatively, if you already have them installed,
-you can use <command>configure</command>'s <option>--with-bdb</option>
-and <option>--with-aterm</option> options to point to their respective
-locations.  Note that Berkeley DB <emphasis>must</emphasis> be version
-4.5; other versions may not have compatible database formats.</para>
+you can use <command>configure</command>'s
+<option>--with-aterm</option> and <option>--with-bzip2</option>
+options to point to their respective locations.</para>
+
+<para>If you want to be able to upgrade Nix stores from before version
+0.12pre12020, you need Sleepycat's Berkeley DB version version 4.5.
+(Other versions may not have compatible database formats.).  Berkeley
+DB 4.5 is included in the Nix source distribution.  If you do not need
+this ability, you can build Nix with the
+<option>--disable-old-db-compat</option> configure option.</para>
 
 </section>
 
@@ -118,19 +121,21 @@ locations.  Note that Berkeley DB <emphasis>must</emphasis> be version
 
 <para>After unpacking or checking out the Nix sources, issue the
 following commands:
-    </para>
 
 <screen>
 $ ./configure <replaceable>options...</replaceable>
 $ make
 $ make install</screen>
 
+</para>
+
 <para>When building from the Subversion repository, these should be
 preceded by the command:
-    </para>
 
 <screen>
-$ ./boostrap</screen>
+$ ./bootstrap</screen>
+
+</para>
 
 <para>The installation path can be specified by passing the
 <option>--prefix=<replaceable>prefix</replaceable></option> to
@@ -157,28 +162,32 @@ options.</para>
 
 <section><title>Installing from RPMs</title>
 
-<para>RPM packages of Nix can be downloaded from <uri
-xlink:href="http://www.cs.uu.nl/groups/ST/Trace/Nix">http://www.cs.uu.nl/groups/ST/Trace/Nix</uri>.
-These RPMs should work for most fairly recent releases of SuSE and Red
-Hat Linux.  They have been known to work work on SuSE Linux 8.1 and
-9.0, and Red Hat 9.0.  In fact, it should work on any RPM-based Linux
-distribution based on <literal>glibc</literal> 2.3 or later.</para>
+<para>RPM packages of Nix can be downloaded from <link
+xlink:href="http://nixos.org/" />.  These RPMs should work for most
+fairly recent releases of SuSE and Red Hat Linux.  They have been
+known to work work on SuSE Linux 8.1 and 9.0, and Red Hat 9.0.  In
+fact, it should work on any RPM-based Linux distribution based on
+<literal>glibc</literal> 2.3 or later.</para>
 
 <para>Once downloaded, the RPMs can be installed or upgraded using
-<command>rpm -U</command>.  For example,</para>
+<command>rpm -U</command>.  For example,
 
 <screen>
 $ rpm -U nix-0.5pre664-1.i386.rpm</screen>
 
+</para>
+
 <para>The RPMs install into the directory <filename>/nix</filename>.
 Nix can be uninstalled using <command>rpm -e nix</command>.  After
 this it will be necessary to manually remove the Nix store and other
-auxiliary data:</para>
+auxiliary data:
 
 <screen>
 $ rm -rf /nix/store
 $ rm -rf /nix/var</screen>
 
+</para>
+
 </section>
 
 
@@ -186,12 +195,12 @@ $ rm -rf /nix/var</screen>
 
 <para>You can install the latest stable version of Nix through Nix
 itself by subscribing to the channel <link
-xlink:href="http://nix.cs.uu.nl/dist/nix/channels-v3/nix-stable" />,
-or the latest unstable version by subscribing to the channel<link
-xlink:href="http://nix.cs.uu.nl/dist/nix/channels-v3/nix-unstable" />.
+xlink:href="http://nixos.org/releases/nix/channels/nix-stable" />,
+or the latest unstable version by subscribing to the channel <link
+xlink:href="http://nixos.org/releases/nix/channels/nix-unstable" />.
 You can also do a <link linkend="sec-one-click">one-click
 installation</link> by clicking on the package links at <link
-xlink:href="http://nix.cs.uu.nl/dist/nix/" />.</para>
+xlink:href="http://nixos.org/releases/full-index-nix.html" />.</para>
 
 </section>
 
@@ -231,33 +240,215 @@ class="username">root</systemitem> all the time.</para>
 </section>
 
 
-<section><title>Multi-user mode</title>
+<section xml:id="ssec-multi-user"><title>Multi-user mode</title>
 
-<para></para>
+<para>To allow a Nix store to be shared safely among multiple users,
+it is important that users are not able to run builders that modify
+the Nix store or database in arbitrary ways, or that interfere with
+builds started by other users.  If they could do so, they could
+install a Trojan horse in some package and compromise the accounts of
+other users.</para>
 
-
-<!--
-
-warning: the nix-builders group should contain *only* the Nix
-builders, and nothing else.  If the Nix account is compromised, you
-can execute programs under the accounts in the nix-builders group, so
-it obviously shouldn’t contain any “real” user accounts.  So don’t use
-an existing group like <literal>users</literal> — just create a new
-one.
-
--->
+<para>To prevent this, the Nix store and database are owned by some
+privileged user (usually <literal>root</literal>) and builders are
+executed under special user accounts (usually named
+<literal>nixbld1</literal>, <literal>nixbld2</literal>, etc.).  When a
+unprivileged user runs a Nix command, actions that operate on the Nix
+store (such as builds) are forwarded to a <emphasis>Nix
+daemon</emphasis> running under the owner of the Nix store/database
+that performs the operation.</para>
 
 <note><para>Multi-user mode has one important limitation: only
 <systemitem class="username">root</systemitem> can run <command
 linkend="sec-nix-pull">nix-pull</command> to register the availability
-of pre-built binaries.  However, those registrations
-<emphasis>are</emphasis> used by all users to speed up
-builds.</para></note>
+of pre-built binaries.  However, those registrations are shared by all
+users, so they still get the benefit from <command>nix-pull</command>s
+done by <systemitem class="username">root</systemitem>.</para></note>
+
+
+<section><title>Setting up the build users</title>
+
+<para>The <emphasis>build users</emphasis> are the special UIDs under
+which builds are performed.  They should all be members of the
+<emphasis>build users group</emphasis> (usually called
+<literal>nixbld</literal>).  This group should have no other members.
+The build users should not be members of any other group.</para>
+
+<para>Here is a typical <filename>/etc/group</filename> definition of
+the build users group with 10 build users:
+
+<programlisting>
+nixbld:!:30000:nixbld1,nixbld2,nixbld3,nixbld4,nixbld5,nixbld6,nixbld7,nixbld8,nixbld9,nixbld10
+</programlisting>
+
+In this example the <literal>nixbld</literal> group has UID 30000, but
+of course it can be anything that doesn’t collide with an existing
+group.</para>
+
+<para>Here is the corresponding part of
+<filename>/etc/passwd</filename>:
+
+<programlisting>
+nixbld1:x:30001:65534:Nix build user 1:/var/empty:/noshell
+nixbld2:x:30002:65534:Nix build user 2:/var/empty:/noshell
+nixbld3:x:30003:65534:Nix build user 3:/var/empty:/noshell
+...
+nixbld10:x:30010:65534:Nix build user 10:/var/empty:/noshell
+</programlisting>
+
+The home directory of the build users should not exist or should be an
+empty directory to which they do not have write access.</para>
+
+<para>The build users should have write access to the Nix store, but
+they should not have the right to delete files.  Thus the Nix store’s
+group should be the build users group, and it should have the sticky
+bit turned on (like <filename>/tmp</filename>):
+
+<screen>
+$ chgrp nixbld /nix/store
+$ chmod 1777 /nix/store
+</screen>
+
+</para>
+
+<para>Finally, you should tell Nix to use the build users by
+specifying the build users group in the <link
+linkend="conf-build-users-group"><literal>build-users-group</literal>
+option</link> in the <link linkend="sec-conf-file">Nix configuration
+file</link> (<literal>/nix/etc/nix/nix.conf</literal>):
+
+<programlisting>
+build-users-group = nixbld
+</programlisting>
+
+</para>
 
 </section>
 
 
-</section> <!-- end of permissions section -->
+<section><title>Nix store/database owned by root</title>
+
+<para>The simplest setup is to let <literal>root</literal> own the Nix
+store and database.  I.e.,
+
+<screen>
+$ chown -R root /nix/store /nix/var/nix</screen>
+
+</para>
+
+<para>The <link linkend="sec-nix-worker">Nix daemon</link> should be
+started as follows (as <literal>root</literal>):
+
+<screen>
+$ nix-worker --daemon</screen>
+
+You’ll want to put that line somewhere in your system’s boot
+scripts.</para>
+
+<para>To let unprivileged users use the daemon, they should set the
+<link linkend="envar-remote"><envar>NIX_REMOTE</envar> environment
+variable</link> to <literal>daemon</literal>.  So you should put a
+line like
+
+<programlisting>
+export NIX_REMOTE=daemon</programlisting>
+
+into the users’ login scripts.</para>
+
+</section>
+
+
+<section><title>Nix store/database not owned by root</title>
+
+<para>It is also possible to let the Nix store and database be owned
+by a non-root user, which should be more secure<footnote><para>Note
+however that even when the Nix daemon runs as root, not
+<emphasis>that</emphasis> much code is executed as root: Nix
+expression evaluation is performed by the calling (unprivileged) user,
+and builds are performed under the special build user accounts.  So
+only the code that accesses the database and starts builds is executed
+as <literal>root</literal>.</para></footnote>.  Typically, this user
+is a special account called <literal>nix</literal>, but it can be
+named anything.  It should own the Nix store and database:
+
+<screen>
+$ chown -R root /nix/store /nix/var/nix</screen>
+
+and of course <command>nix-worker --daemon</command> should be started
+under that user, e.g.,
+
+<screen>
+$ su - nix -c "exec /nix/bin/nix-worker --daemon"</screen>
+
+</para>
+
+<para>There is a catch, though: non-<literal>root</literal> users
+cannot start builds under the build user accounts, since the
+<function>setuid</function> system call is obviously privileged.  To
+allow a non-<literal>root</literal> Nix daemon to use the build user
+feature, it calls a setuid-root helper program,
+<command>nix-setuid-helper</command>.  This program is installed in
+<filename><replaceable>prefix</replaceable>/libexec/nix-setuid-helper</filename>.
+To set the permissions properly (Nix’s <command>make install</command>
+doesn’t do this, since we don’t want to ship setuid-root programs
+out-of-the-box):
+
+<screen>
+$ chown root.root /nix/libexec/nix-setuid-helper
+$ chmod 4755 /nix/libexec/nix-setuid-helper
+</screen>
+
+(This example assumes that the Nix binaries are installed in
+<filename>/nix</filename>.)</para>
+
+<para>Of course, the <command>nix-setuid-helper</command> command
+should not be usable by just anybody, since then anybody could run
+commands under the Nix build user accounts.  For that reason there is
+a configuration file <filename>/etc/nix-setuid.conf</filename> that
+restricts the use of the helper.  This file should be a text file
+containing precisely two lines, the first being the Nix daemon user
+and the second being the build users group, e.g.,
+
+<programlisting>
+nix
+nixbld
+</programlisting>
+
+The setuid-helper barfs if it is called by a user other than the one
+specified on the first line, or if it is asked to execute a build
+under a user who is not a member of the group specified on the second
+line.  The file <filename>/etc/nix-setuid.conf</filename> must be
+owned by root, and must not be group- or world-writable.  The
+setuid-helper barfs if this is not the case.</para>
+
+</section>
+
+
+<section><title>Restricting access</title>
+
+<para>To limit which users can perform Nix operations, you can use the
+permissions on the directory
+<filename>/nix/var/nix/daemon-socket</filename>.  For instance, if you
+want to restrict the use of Nix to the members of a group called
+<literal>nix-users</literal>, do
+
+<screen>
+$ chgrp nix-users /nix/var/nix/daemon-socket
+$ chmod ug=rwx,o= /nix/var/nix/daemon-socket
+</screen>
+
+This way, users who are not in the <literal>nix-users</literal> group
+cannot connect to the Unix domain socket
+<filename>/nix/var/nix/daemon-socket/socket</filename>, so they cannot
+perform Nix operations.</para>
+
+</section>
+
+
+</section> <!-- end of multi-user -->
+
+
+</section> <!-- end of security -->
 
 
 <section><title>Using Nix</title>

doc/manual/introduction.xml

@@ -1,150 +1,337 @@
 <chapter xmlns="http://docbook.org/ns/docbook"
-         xmlns:xlink="http://www.w3.org/1999/xlink">
+         xmlns:xlink="http://www.w3.org/1999/xlink"
+         xml:id="chap-introduction">
 
 <title>Introduction</title>
 
-<para>Nix is a system for the deployment of software.  Software
-deployment is concerned with the creation, distribution, and
-management of software components (<quote>packages</quote>).  Its main
-features are:
 
-<itemizedlist>
+<section><title>About Nix</title>
 
-<listitem><para>It helps you make sure that dependency specifications
-are complete.  In general in a deployment system you have to specify
-for each component what its dependencies are, but there are no
-guarantees that this specification is complete.  If you forget a
-dependency, then the component will build and work correctly on
-<emphasis>your</emphasis> machine if you have the dependency
-installed, but not on the end user's machine if it's not
-there.</para></listitem>
+<para>Nix is a <emphasis>purely functional package manager</emphasis>.
+This means that it treats packages like values in purely functional
+programming languages such as Haskell — they are built by functions
+that don’t have side-effects, and they never change after they have
+been built.  Nix stores packages in the <emphasis>Nix
+store</emphasis>, usually the directory
+<filename>/nix/store</filename>, where each package has its own unique
+subdirectory such as
 
-<listitem><para>It is possible to have <emphasis>multiple versions or
-variants</emphasis> of a component installed at the same time.  In
-contrast, in systems such as RPM different versions of the same
-package tend to install to the same location in the file system, so
-installing one version will remove the other.  This is especially
-important if you want to use applications that have conflicting
-requirements on different versions of a component (e.g., application A
-requires version 1.0 of library X, while application B requires a
-non-backwards compatible version 1.1).</para></listitem>
+<programlisting>
+/nix/store/r8vvq9kq18pz08v249h8my6r9vs7s0n3-firefox-2.0.0.1/
+</programlisting>
 
-<listitem><para>Users can have different <quote>views</quote>
-(<quote>profiles</quote> in Nix parlance) on the set of installed
-applications in a system.  For instance, one user can have version 1.0
-of some package visible, while another is using version 1.1, and a
-third doesn't use it at all.</para></listitem>
+where <literal>r8vvq9kq…</literal> is a unique identifier for the
+package that captures all its dependencies (it’s a cryptographic hash
+of the package’s build dependency graph).  This enables many powerful
+features.</para>
 
-<listitem><para>It is possible to atomically
-<emphasis>upgrade</emphasis> software.  I.e., there is no time window
-during an upgrade in which part of the old version and part of the new
-version are simultaneously visible (which might well cause the
-component to fail).</para></listitem>
 
-<listitem><para>Likewise, it is possible to atomically roll back after
-an install, upgrade, or uninstall action.  That is, in a fast (O(1))
-operation the previous configuration of the system can be restored.
-This is because upgrade or uninstall actions don't actually remove
-components from the system.</para></listitem>
+<simplesect><title>Multiple versions</title>
 
-<listitem><para>Unused components can be
-<emphasis>garbage-collected</emphasis> automatically and safely: when
-you remove an application from a profile, its dependencies will be
-deleted by the garbage collector only if there are no other active
-applications using them.</para></listitem>
+<para>You can have multiple versions or variants of a package
+installed at the same time.  This is especially important when
+different applications have dependencies on different versions of the
+same package — it prevents the “DLL hell”.  Because of the hashing
+scheme, different versions of a package end up in different paths in
+the Nix store, so they don’t interfere with each other.</para>
 
-<listitem><para>Nix supports both source-based deployment models
-(where you distribute <emphasis>Nix expressions</emphasis> that tell
-Nix how to build software from source) and binary-based deployment
-models.  The latter is more-or-less transparent: installation of
-components is always based on Nix expressions, but if the expressions
-have been built before and Nix knows that the resulting binaries are
-available somewhere, it will use those instead.</para></listitem>
+<para>An important consequence is that operations like upgrading or
+uninstalling an application cannot break other applications, since
+these operations never “destructively” update or delete files that are
+used by other packages.</para>
 
-<listitem><para>Nix is flexible in the deployment policies that it
-supports.  There is a clear separation between the tools that
-implement basic Nix <emphasis>mechanisms</emphasis> (e.g., building
-Nix expressions), and the tools that implement various deployment
-<emphasis>policies</emphasis>.  For instance, there is a concept of
-<quote>Nix channels</quote> that can be used to keep software
-installations up-to-date automatically from a network source.  This is
-a policy that is implemented by a fairly short Perl script, which can
-be adapted easily to achieve similar policies.</para></listitem>
+</simplesect>
 
-<listitem><para>Nix component builds aim to be <quote>pure</quote>;
-that is, unaffected by anything other than the declared dependencies.
-This means that if a component was built successfully once, it can be
-rebuilt again on another machine and the result will be the same.  We
-cannot <emphasis>guarantee</emphasis> this (e.g., if the build depends
-on the time-of-day), but Nix (and the tools in the Nix Packages
-collection) takes special care to help achieve this.</para></listitem>
 
-<listitem><para>Nix expressions (the things that tell Nix how to build
-components) are self-contained: they describe not just components but
-complete compositions.  In other words, Nix expressions also describe
-how to build all the dependencies.  This is in contrast to component
-specification languages like RPM spec files, which might say that a
-component X depends on some other component Y, but since it does not
-describe <emphasis>exactly</emphasis> what Y is, the result of
-building or running X might be different on different machines.
-Combined with purity, self-containedness ensures that a component that
-<quote>works</quote> on one machine also works on another, when
-deployed using Nix.</para></listitem>
+<simplesect><title>Complete dependencies</title>
 
-<listitem><para>The Nix expression language makes it easy to describe
-variability in components (e.g., optional features or
-dependencies).</para></listitem>
+<para>Nix helps you make sure that package dependency specifications
+are complete.  In general, when you’re making a package for a package
+management system like RPM, you have to specify for each package what
+its dependencies are, but there are no guarantees that this
+specification is complete.  If you forget a dependency, then the
+package will build and work correctly on <emphasis>your</emphasis>
+machine if you have the dependency installed, but not on the end
+user's machine if it's not there.</para>
 
-<listitem><para>Nix is ideal for building build farms that do
-continuous builds of software from a version management system, since
-it can take care of building all the dependencies as well.  Also, Nix
-only rebuilds components that have changed, so there are no
-unnecessary builds.  In addition, Nix can transparently distribute
-build jobs over different machines, including different
-platforms.</para></listitem>
+<para>Since Nix on the other hand doesn’t install packages in “global”
+locations like <filename>/usr/bin</filename> but in package-specific
+directories, the risk of incomplete dependencies is greatly reduced.
+This is because tools such as compilers don’t search in per-packages
+directories such as
+<filename>/nix/store/5lbfaxb722zp…-openssl-0.9.8d/include</filename>,
+so if a package builds correctly on your system, this is because you
+specified the dependency explicitly.</para>
 
-<listitem><para>Nix can be used not only for software deployment, but
-also for <emphasis>service deployment</emphasis>, such as the
-deployment of a complete web server with all its configuration files,
-static pages, software dependencies, and so on.  Nix's advantages for
-software deployment also apply here: for instance, the ability
-trivially to have multiple configurations at the same time, or the
-ability to do rollbacks.</para></listitem>
+<para>Runtime dependencies are found by scanning binaries for the hash
+parts of Nix store paths (such as <literal>r8vvq9kq…</literal>).  This
+sounds risky, but it works extremely well.</para>
 
-<listitem><para>Nix can efficiently upgrade between different versions
-of a component through <emphasis>binary patching</emphasis>.  If
-patches are available on a server, and you try to install a new
-version of some component, Nix will automatically apply a patch (or
-sequence of patches), if available, to transform the installed
-component into the new version.</para></listitem> 
+</simplesect>
 
-</itemizedlist>
 
-</para>
+<simplesect><title>Multi-user support</title>
+
+<para>Starting at version 0.11, Nix has multi-user support.  This
+means that non-privileged users can securely install software.  Each
+user can have a different <emphasis>profile</emphasis>, a set of
+packages in the Nix store that appear in the user’s
+<envar>PATH</envar>.  If a user installs a package that another user
+has already installed previously, the package won’t be built or
+downloaded a second time.  At the same time, it is not possible for
+one user to inject a Trojan horse into a package that might be used by
+another user.</para>
+
+<!--
+<para>More details can be found in Section 3 of our <a
+href="docs/papers.html#securesharing">ASE 2005 paper</a>.</para>
+-->
+
+</simplesect>
+
+
+<simplesect><title>Atomic upgrades and rollbacks</title>
+
+<para>Since package management operations never overwrite packages in
+the Nix store but just add new versions in different paths, they are
+<emphasis>atomic</emphasis>.  So during a package upgrade, there is no
+time window in which the package has some files from the old version
+and some files from the new version — which would be bad because a
+program might well crash if it’s started during that period.</para>
+
+<para>And since package aren’t overwritten, the old versions are still
+there after an upgrade.  This means that you can <emphasis>roll
+back</emphasis> to the old version:</para>
+
+<screen>
+$ nix-env --upgrade <replaceable>some-packages</replaceable>
+$ nix-env --rollback
+</screen>
+
+</simplesect>
+
+
+<simplesect><title>Garbage collection</title>
+
+<para>When you install a package like this…
+
+<screen>
+$ nix-env --uninstall firefox
+</screen>
+
+the package isn’t deleted from the system right away (after all, you
+might want to do a rollback, or it might be in the profiles of other
+users).  Instead, unused packages can be deleted safely by running the
+<emphasis>garbage collector</emphasis>:
+
+<screen>
+$ nix-collect-garbage
+</screen>
+
+This deletes all packages that aren’t in use by any user profile or by
+a currently running program.</para>
+
+</simplesect>
+
+
+<simplesect><title>Functional package language</title>
+
+<para>Packages are built from <emphasis>Nix expressions</emphasis>,
+which is a simple functional language.  A Nix expression describes
+everything that goes into a package build action (a “derivation”):
+other packages, sources, the build script, environment variables for
+the build script, etc.  Nix tries very hard to ensure that Nix
+expressions are <emphasis>deterministic</emphasis>: building a Nix
+expression twice should yield the same result.</para>
+
+<para>Because it’s a functional language, it’s easy to support
+building variants of a package: turn the Nix expression into a
+function and call it any number of times with the appropriate
+arguments.  Due to the hashing scheme, variants don’t conflict with
+each other in the Nix store.</para>
+
+</simplesect>
+
+
+<simplesect><title>Transparent source/binary deployment</title>
+
+<para>Nix expressions generally describe how to build a package from
+source, so an installation action like
+
+<screen>
+$ nix-env --install firefox
+</screen>
+
+<emphasis>could</emphasis> cause quite a bit of build activity, as not
+only Firefox but also all its dependencies (all the way up to the C
+library and the compiler) would have to built, at least if they are
+not already in the Nix store.  This is a <emphasis>source deployment
+model</emphasis>.  For most users, building from source is not very
+pleasant as it takes far too long.  However, Nix can automatically
+skip building from source and download a pre-built binary instead if
+it knows about it.  <emphasis>Nix channels</emphasis> provide Nix
+expressions along with pre-built binaries.</para>
+
+<!--
+<para>source deployment model (like <a
+href="http://www.gentoo.org/">Gentoo</a>) and a binary model (like
+RPM)</para>
+-->
+
+</simplesect>
+
+
+<simplesect><title>Binary patching</title>
+
+<para>In addition to downloading binaries automatically if they’re
+available, Nix can download binary deltas that patch an existing
+package in the Nix store into a new version.  This speeds up
+upgrades.</para>
+
+</simplesect>
+
+
+<simplesect><title>Nix Packages collection</title>
+
+<para>We provide a large set of Nix expressions containing hundreds of
+existing Unix packages, the <emphasis>Nix Packages
+collection</emphasis> (Nixpkgs).</para>
+
+</simplesect>
+
+
+<simplesect><title>Service deployment</title>
+
+<para>Nix can be used not only for rolling out packages, but also
+complete <emphasis>configurations</emphasis> of services.  This is
+done by treating all the static bits of a service (such as software
+packages, configuration files, control scripts, static web pages,
+etc.) as “packages” that can be built by Nix expressions.  As a
+result, all the features above apply to services as well: for
+instance, you can roll back a web server configuration if a
+configuration change turns out to be undesirable, you can easily have
+multiple instances of a service (e.g., a test and production server),
+and because the whole service is built in a purely functional way from
+a Nix expression, it is repeatable so you can easily reproduce the
+service on another machine.</para>
+
+<!--
+<para>You can read more about this in our <a
+href="docs/papers.html#servicecm">SCM-12 paper</a>.</para>
+-->
+
+</simplesect>
+
+
+<simplesect><title>Portability</title>
+
+<para>Nix should run on most Unix systems, including Linux, FreeBSD and
+Mac OS X.  It is also supported on Windows using Cygwin.</para>
+
+</simplesect>
+
+
+<simplesect><title>NixOS</title>
+
+<para>NixOS is a Linux distribution based on Nix.  It uses Nix not
+just for package management but also to manage the system
+configuration (e.g., to build configuration files in
+<filename>/etc</filename>).  This means, among other things, that it’s
+possible to easily roll back the entire configuration of the system to
+an earlier state.  Also, users can install software without root
+privileges.  For more information and downloads, see the <link
+xlink:href="http://nixos.org/">NixOS homepage</link>.</para>
+
+</simplesect>
+
+
+<!-- other features:
+
+- build farms
+- reproducibility (Nix expressions allows whole configuration to be rebuilt)
+
+-->
+
+</section>
+
+
+<section><title>About us</title>
+
+<para>Nix was originally developed at the <link
+xlink:href="http://www.cs.uu.nl/">Department of Information and
+Computing Sciences</link>, Utrecht University by the <link
+xlink:href="http://www.cs.uu.nl/wiki/Trace/WebHome">TraCE
+project</link> (2003-2008).  The project was funded by the Software
+Engineering Research Program <link
+xlink:href="http://www.jacquard.nl/">Jacquard</link> to improve the
+support for variability in software systems.  Further funding is now
+provided by the NIRICT LaQuSo Build Farm project.</para>
+
+</section>
+
+
+<section><title>About this manual</title>
 
 <para>This manual tells you how to install and use Nix and how to
 write Nix expressions for software not already in the Nix Packages
 collection.  It also discusses some advanced topics, such as setting
-up a Nix-based build farm, and doing service deployment using
-Nix.</para>
+up a Nix-based build farm.</para>
 
-<note><para>Some background information on Nix can be found in a
-number of papers.  The ICSE 2004 paper <citetitle
-xlink:href='http://www.cs.uu.nl/~eelco/pubs/immdsd-icse2004-final.pdf'>Imposing
+</section>
+
+
+<section><title>License</title>
+
+<para>Nix is free software; you can redistribute it and/or modify it
+under the terms of the <link
+xlink:href="http://www.gnu.org/licenses/lgpl.html">GNU Lesser General
+Public License</link> as published by the <link
+xlink:href="http://www.fsf.org/">Free Software Foundation</link>;
+either version 2.1 of the License, or (at your option) any later
+version.  Nix is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Lesser General Public License for more details.</para>
+
+</section>
+
+
+<section><title>More information</title>
+
+<para>Some background information on Nix can be found in a number of
+papers.  The ICSE 2004 paper <citetitle
+xlink:href='http://www.st.ewi.tudelft.nl/~dolstra/pubs/immdsd-icse2004-final.pdf'>Imposing
 a Memory Management Discipline on Software Deployment</citetitle>
 discusses the hashing mechanism used to ensure reliable dependency
 identification and non-interference between different versions and
 variants of packages.  The LISA 2004 paper <citetitle
-xlink:href='http://www.cs.uu.nl/~eelco/pubs/nspfssd-lisa2004-final.pdf'>Nix:
+xlink:href='http://www.st.ewi.tudelft.nl/~dolstra/pubs/nspfssd-lisa2004-final.pdf'>Nix:
 A Safe and Policy-Free System for Software Deployment</citetitle>
 gives a more general discussion of Nix from a system-administration
 perspective.  The CBSE 2005 paper <citetitle
-xlink:href='http://www.cs.uu.nl/~eelco/pubs/eupfcdm-cbse2005-final.pdf'>Efficient
+xlink:href='http://www.st.ewi.tudelft.nl/~dolstra/pubs/eupfcdm-cbse2005-final.pdf'>Efficient
 Upgrading in a Purely Functional Component Deployment Model
-</citetitle> is about transparent patch deployment in Nix.  Finally,
-the SCM-12 paper <citetitle
-xlink:href='http://www.cs.uu.nl/~eelco/pubs/servicecm-scm12-final.pdf'>
+</citetitle> is about transparent patch deployment in Nix.  The SCM-12
+paper <citetitle
+xlink:href='http://www.st.ewi.tudelft.nl/~dolstra/pubs/servicecm-scm12-final.pdf'>
 Service Configuration Management</citetitle> shows how services (e.g.,
-web servers) can be deployed and managed through Nix.</para></note>
+web servers) can be deployed and managed through Nix.  A short
+overview of NixOS is given in the HotOS XI paper <citetitle
+xlink:href="http://www.st.ewi.tudelft.nl/~dolstra/pubs/hotos-final.pdf">Purely
+Functional System Configuration Management</citetitle>.  The Nix
+homepage has <link
+xlink:href="http://nix.cs.uu.nl/docs/papers.html">an up-to-date list
+of Nix-related papers</link>.</para>
+
+<para>Nix is the subject of Eelco Dolstra’s PhD thesis <citetitle
+xlink:href="http://igitur-archive.library.uu.nl/dissertations/2006-0118-200031/index.htm">The
+Purely Functional Software Deployment Model</citetitle>, which
+contains most of the papers listed above.</para>
+
+<para>Nix has a homepage at <link
+xlink:href="http://nixos.org/"/>.</para>
+
+</section>
+
 
 </chapter>

doc/manual/manual.xml

@@ -14,8 +14,8 @@
         <surname>Dolstra</surname>
       </personname>
       <affiliation>
-        <orgname>Utrecht University</orgname>
-        <orgdiv>Faculty of Science, Department of Information and Computing Sciences</orgdiv>
+        <orgname>Delft University of Technology</orgname>
+        <orgdiv>Department of Software Technology</orgdiv>
       </affiliation>
     </author>
 
@@ -24,10 +24,11 @@
       <year>2005</year>
       <year>2006</year>
       <year>2007</year>
+      <year>2008</year>
       <holder>Eelco Dolstra</holder>
     </copyright>
 
-    <date>September 2007</date>
+    <date>November 2008</date>
     
   </info>
 
@@ -88,10 +89,6 @@
         <title>nix-install-package</title>
         <xi:include href="nix-install-package.xml" />
       </section>
-      <section xml:id="sec-nix-pack-closure">
-        <title>nix-pack-closure</title>
-        <xi:include href="nix-pack-closure.xml" />
-      </section>
       <section xml:id="sec-nix-prefetch-url">
         <title>nix-prefetch-url</title>
         <xi:include href="nix-prefetch-url.xml" />
@@ -104,9 +101,9 @@
         <title>nix-push</title>
         <xi:include href="nix-push.xml" />
       </section>
-      <section xml:id="sec-nix-unpack-closure">
-        <title>nix-unpack-closure</title>
-        <xi:include href="nix-unpack-closure.xml" />
+      <section xml:id="sec-nix-worker">
+        <title>nix-worker</title>
+        <xi:include href="nix-worker.xml" />
       </section>
     </section>
     

doc/manual/nix-build.xml

@@ -19,6 +19,7 @@
     <command>nix-build</command>
     <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="opt-common-syn.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(/db:nop/*)" />
     <arg><option>--arg</option> <replaceable>name</replaceable> <replaceable>value</replaceable></arg>
+    <arg><option>--argstr</option> <replaceable>name</replaceable> <replaceable>value</replaceable></arg>
     <arg>
       <group choice='req'>
         <arg choice='plain'><option>--attr</option></arg>

doc/manual/nix-channel.xml

@@ -62,11 +62,11 @@ also <xref linkend="sec-channels" />.</para>
   <varlistentry><term><option>--update</option></term>
 
     <listitem><para>Downloads the Nix expressions of all subscribed
-    channels, makes the conjunction of these the default for
-    <command>nix-env</command> operations (by calling <command>nix-env
-    -I</command>), and performs a <command>nix-pull</command> on the
-    manifests of all channels to make pre-built binaries
-    available.</para></listitem>
+    channels, makes them the default for <command>nix-env</command>
+    operations (by symlinking them in the directory
+    <filename>~/.nix-defexpr</filename>), and performs a
+    <command>nix-pull</command> on the manifests of all channels to
+    make pre-built binaries available.</para></listitem>
 
   </varlistentry>
 

doc/manual/nix-copy-closure.xml

@@ -128,7 +128,7 @@ those paths.  If this bothers you, use
 <para>Copy Firefox with all its dependencies to a remote machine:
 
 <screen>
-$ nix-copy-closure alice@itchy.labs $(type -tP firefox)</screen>
+$ nix-copy-closure --to alice@itchy.labs $(type -tP firefox)</screen>
 
 </para>
 

doc/manual/nix-env.xml

@@ -19,13 +19,7 @@
     <command>nix-env</command>
     <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="opt-common-syn.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(/db:nop/*)" />
     <arg><option>--arg</option> <replaceable>name</replaceable> <replaceable>value</replaceable></arg>
-    <arg>
-      <group choice='req'>
-        <arg choice='plain'><option>--attr</option></arg>
-        <arg choice='plain'><option>-A</option></arg>
-      </group>
-      <replaceable>attrPath</replaceable>
-    </arg>
+    <arg><option>--argstr</option> <replaceable>name</replaceable> <replaceable>value</replaceable></arg>
     <arg>
       <group choice='req'>
         <arg choice='plain'><option>--file</option></arg>
@@ -45,9 +39,6 @@
       <replaceable>system</replaceable>
     </arg>
     <arg><option>--dry-run</option></arg>
-    <arg><option>--from-expression</option></arg>
-    <arg><option>-E</option></arg>
-    <arg><option>--from-profile</option> <replaceable>path</replaceable></arg>
     <arg choice='plain'><replaceable>operation</replaceable></arg>
     <arg rep='repeat'><replaceable>options</replaceable></arg>
     <arg rep='repeat'><replaceable>arguments</replaceable></arg>
@@ -58,7 +49,7 @@
 <refsection><title>Description</title>
 
 <para>The command <command>nix-env</command> is used to manipulate Nix
-user environments.  User environments are sets of software components
+user environments.  User environments are sets of software packages
 available to a user at some point in time.  In other words, they are a
 synthesised view of the programs available in the Nix store.  There
 may be many user environments: different users can have different
@@ -151,13 +142,33 @@ linkend="sec-common-options" />.</para>
 
   <varlistentry><term><filename>~/.nix-defexpr</filename></term>
 
-  <!-- !!! .nix-defexpr can be a directory now -->
-  
-    <listitem><para>The default Nix expression used by the
-    <option>--install</option>, <option>--upgrade</option>, and
-    <option>--query --available</option> operations to obtain
-    derivations.  The <option>--file</option> option may be used to
-    override this default.</para></listitem>
+    <listitem><para>A directory that contains the default Nix
+    expressions used by the <option>--install</option>,
+    <option>--upgrade</option>, and <option>--query
+    --available</option> operations to obtain derivations.  The
+    <option>--file</option> option may be used to override this
+    default.</para>
+
+    <para>The Nix expressions in this directory are combined into a
+    single attribute set, with each file as an attribute that has the
+    name of the file.  Thus, if <filename>~/.nix-defexpr</filename>
+    contains two files, <filename>foo</filename> and
+    <filename>bar</filename>, then the default Nix expression will
+    essentially be
+
+<programlisting>
+{
+  foo = import ~/.nix-defexpr/foo;
+  bar = import ~/.nix-defexpr/bar;
+}</programlisting>
+
+    </para>
+
+    <para>The command <command>nix-channel</command> places symlinks
+    to the downloaded Nix expressions from each subscribed channel in
+    this directory.</para>
+
+    </listitem>
     
   </varlistentry>
 
@@ -190,6 +201,7 @@ linkend="sec-common-options" />.</para>
     <arg choice='plain'><option>--install</option></arg>
     <arg choice='plain'><option>-i</option></arg>
   </group>
+  <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="opt-inst-syn.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(/db:nop/*)" />
   <group choice='opt'>
     <arg choice='plain'><option>--preserve-installed</option></arg>
     <arg choice='plain'><option>-P</option></arg>
@@ -221,11 +233,21 @@ number of possible ways:
   <para>If there are multiple derivations matching a name in
   <replaceable>args</replaceable> that have the same name (e.g.,
   <literal>gcc-3.3.6</literal> and <literal>gcc-4.1.1</literal>), then
-  only the highest version will be installed.  You can force the
-  installation of multiple derivations with the same name by being
-  specific about the versions.  For instance, <literal>nix-env -i
-  gcc-3.3.6 gcc-4.1.1</literal> will install both version of GCC (and
-  will probably cause a user environment conflict!).</para></listitem>
+  the derivation with the highest <emphasis>priority</emphasis> is
+  used.  A derivation can define a priority by declaring the
+  <varname>meta.priority</varname> attribute.  This attribute should
+  be a number, with a higher value denoting a lower priority.  The
+  default priority is <literal>0</literal>.</para>
+
+  <para>If there are multiple matching derivations with the same
+  priority, then the derivation with the highest version will be
+  installed.</para>
+
+  <para>You can force the installation of multiple derivations with
+  the same name by being specific about the versions.  For instance,
+  <literal>nix-env -i gcc-3.3.6 gcc-4.1.1</literal> will install both
+  version of GCC (and will probably cause a user environment
+  conflict!).</para></listitem>
 
   <listitem><para>If <link
   linkend='opt-attr'><option>--attr</option></link>
@@ -272,6 +294,15 @@ number of possible ways:
 
 <variablelist>
 
+  <varlistentry><term><option>--prebuild-only</option> / <option>-b</option></term>
+
+    <listitem><para>Use only derivations for which a substitute is
+    registered, i.e., there is a pre-built binary available that can
+    be downloaded in lieu of building the derivation.  Thus, no
+    packages will be built from source.</para></listitem>
+
+  </varlistentry>
+
   <varlistentry><term><option>--preserve-installed</option></term>
     <term><option>-P</option></term>
   
@@ -387,7 +418,7 @@ the following paths will be substituted:
   
 <!--######################################################################-->
 
-<refsection><title>Operation <option>--upgrade</option></title>
+<refsection xml:id="rsec-nix-env-upgrade"><title>Operation <option>--upgrade</option></title>
 
 <refsection><title>Synopsis</title>
 
@@ -397,6 +428,7 @@ the following paths will be substituted:
     <arg choice='plain'><option>--upgrade</option></arg>
     <arg choice='plain'><option>-u</option></arg>
   </group>
+  <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="opt-inst-syn.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(/db:nop/*)" />
   <group choice='opt'>
     <arg choice='plain'><option>--lt</option></arg>
     <arg choice='plain'><option>--leq</option></arg>
@@ -471,6 +503,9 @@ installed.</para>
 
 </variablelist>
 
+<para>For the other flags, see <option
+linkend="rsec-nix-env-install">--install</option>.</para>
+
 </refsection>
 
 <refsection><title>Examples</title>
@@ -491,7 +526,7 @@ upgrading `mozilla-1.2' to `mozilla-1.4'</screen>
 
 </refsection>
     
-<refsection><title>Versions</title>
+<refsection xml:id="ssec-version-comparisons"><title>Versions</title>
 
 <para>The upgrade operation determines whether a derivation
 <varname>y</varname> is an upgrade of a derivation
@@ -580,6 +615,111 @@ $ nix-env -e '*' <lineannotation>(remove everything)</lineannotation></screen>
 
 
   
+<!--######################################################################-->
+
+<refsection xml:id="rsec-nix-env-set-flag"><title>Operation <option>--set-flag</option></title>
+
+<refsection><title>Synopsis</title>
+
+<cmdsynopsis>
+  <command>nix-env</command>
+  <arg choice='plain'><option>--set-flag</option></arg>
+  <arg choice='plain'><replaceable>name</replaceable></arg>
+  <arg choice='plain'><replaceable>value</replaceable></arg>
+  <arg choice='plain' rep='repeat'><replaceable>drvnames</replaceable></arg>
+</cmdsynopsis>
+</refsection>
+
+<refsection><title>Description</title>
+            
+<para>The <option>--set-flag</option> operation allows meta attributes
+of installed packages to be modified.  There are several attributes
+that can be usefully modified, because they affect the behaviour of
+<command>nix-env</command> or the user environment build
+script:
+
+<itemizedlist>
+
+  <listitem><para><varname>priority</varname> can be changed to
+  resolve filename clashes.  The user environment build script uses
+  the <varname>meta.priority</varname> attribute of derivations to
+  resolve filename collisions between packages.  Lower priority values
+  denote a higher priority.  For instance, the GCC wrapper package and
+  the Binutils package in Nixpkgs both have a file
+  <filename>bin/ld</filename>, so previously if you tried to install
+  both you would get a collision.  Now, on the other hand, the GCC
+  wrapper declares a higher priority than Binutils, so the former’s
+  <filename>bin/ld</filename> is symlinked in the user
+  environment.</para></listitem>
+
+  <listitem><para><varname>keep</varname> can be set to
+  <literal>true</literal> to prevent the package from being upgraded
+  or replaced.  This is useful if you want to hang on to an older
+  version of a package.</para></listitem>
+
+  <listitem><para><varname>active</varname> can be set to
+  <literal>false</literal> to “disable” the package.  That is, no
+  symlinks will be generated to the files of the package, but it
+  remains part of the profile (so it won’t be garbage-collected).  It
+  can be set back to <literal>true</literal> to re-enable the
+  package.</para></listitem>
+
+</itemizedlist>
+
+</para>
+
+</refsection>
+            
+<refsection><title>Examples</title>
+
+<para>To prevent the currently installed Firefox from being upgraded:
+
+<screen>
+$ nix-env --set-flag keep true firefox</screen>
+
+After this, <command>nix-env -u</command> will ignore Firefox.</para>
+
+<para>To disable the currently installed Firefox, then install a new
+Firefox while the old remains part of the profile:
+
+<screen>
+$ nix-env -q \*
+firefox-2.0.0.9 <lineannotation>(the current one)</lineannotation>
+
+$ nix-env --preserve-installed -i firefox-2.0.0.11
+installing `firefox-2.0.0.11'
+building path(s) `/nix/store/myy0y59q3ig70dgq37jqwg1j0rsapzsl-user-environment'
+Collission between `/nix/store/<replaceable>...</replaceable>-firefox-2.0.0.11/bin/firefox'
+  and `/nix/store/<replaceable>...</replaceable>-firefox-2.0.0.9/bin/firefox'.
+<lineannotation>(i.e., can’t have two active at the same time)</lineannotation>
+
+$ nix-env --set-flag active false firefox
+setting flag on `firefox-2.0.0.9'
+
+$ nix-env --preserve-installed -i firefox-2.0.0.11
+installing `firefox-2.0.0.11'
+
+$ nix-env -q \*
+firefox-2.0.0.11 <lineannotation>(the enabled one)</lineannotation>
+firefox-2.0.0.9 <lineannotation>(the disabled one)</lineannotation></screen>
+
+</para>
+
+<para>To make files from <literal>binutils</literal> take precedence
+over files from <literal>gcc</literal>:
+
+<screen>
+$ nix-env --set-flag priority 5 binutils
+$ nix-env --set-flag priority 10 gcc</screen>
+
+</para>
+
+</refsection>
+    
+</refsection>
+
+
+  
 <!--######################################################################-->
   
 <refsection><title>Operation <option>--query</option></title>
@@ -592,13 +732,14 @@ $ nix-env -e '*' <lineannotation>(remove everything)</lineannotation></screen>
     <arg choice='plain'><option>--query</option></arg>
     <arg choice='plain'><option>-q</option></arg>
   </group>
-  <arg><option>--xml</option></arg>
   <group choice='opt'>
     <arg choice='plain'><option>--installed</option></arg>
     <arg choice='plain'><option>--available</option></arg>
     <arg choice='plain'><option>-a</option></arg>
   </group>
+  
   <sbr />
+  
   <arg>
     <group choice='req'>
       <arg choice='plain'><option>--status</option></arg>
@@ -607,8 +748,8 @@ $ nix-env -e '*' <lineannotation>(remove everything)</lineannotation></screen>
   </arg>
   <arg>
     <group choice='req'>
-      <arg choice='plain'><option>--attr</option></arg>
-      <arg choice='plain'><option>-A</option></arg>
+      <arg choice='plain'><option>--attr-path</option></arg>
+      <arg choice='plain'><option>-P</option></arg>
     </group>
   </arg>
   <arg><option>--no-name</option></arg>
@@ -622,6 +763,28 @@ $ nix-env -e '*' <lineannotation>(remove everything)</lineannotation></screen>
   <arg><option>--drv-path</option></arg>
   <arg><option>--out-path</option></arg>
   <arg><option>--description</option></arg>
+  <arg><option>--meta</option></arg>
+
+  <sbr />
+
+  <arg><option>--xml</option></arg>
+  <arg>
+    <group choice='req'>
+      <arg choice='plain'><option>--prebuilt-only</option></arg>
+      <arg choice='plain'><option>-b</option></arg>
+    </group>
+  </arg>
+
+  <arg>
+    <group choice='req'>
+      <arg choice='plain'><option>--attr</option></arg>
+      <arg choice='plain'><option>-A</option></arg>
+    </group>
+    <replaceable>attribute-path</replaceable>
+  </arg>
+
+  <sbr />
+  
   <arg choice='plain' rep='repeat'><replaceable>names</replaceable></arg>
 </cmdsynopsis>
 
@@ -698,6 +861,16 @@ user environment elements, etc. -->
 
   </varlistentry>
 
+  <varlistentry><term><option>--prebuild-only</option> / <option>-b</option></term>
+
+    <listitem><para>Show only derivations for which a substitute is
+    registered, i.e., there is a pre-built binary available that can
+    be downloaded in lieu of building the derivation.  Thus, this
+    shows all packages that probably can be installed
+    quickly.</para></listitem>
+
+  </varlistentry>
+
   <varlistentry><term><option>--status</option></term>
     <term><option>-s</option></term>
   
@@ -717,8 +890,8 @@ user environment elements, etc. -->
     
   </varlistentry>
 
-  <varlistentry><term><option>--attr</option></term>
-    <term><option>-a</option></term>
+  <varlistentry><term><option>--attr-path</option></term>
+    <term><option>-P</option></term>
 
     <listitem><para>Print the <emphasis>attribute path</emphasis> of
     the derivation, which can be used to unambiguously select it using
@@ -741,35 +914,35 @@ user environment elements, etc. -->
     <listitem><para>Compare installed versions to available versions,
     or vice versa (if <option>--available</option> is given).  This is
     useful for quickly seeing whether upgrades for installed
-    components are available in a Nix expression.  A column is added
+    packages are available in a Nix expression.  A column is added
     with the following meaning:
 
     <variablelist>
 
       <varlistentry><term><literal>&lt;</literal> <replaceable>version</replaceable></term>
 
-        <listitem><para>A newer version of the component is available
+        <listitem><para>A newer version of the package is available
         or installed.</para></listitem>
 
       </varlistentry>
       
       <varlistentry><term><literal>=</literal> <replaceable>version</replaceable></term>
 
-        <listitem><para>At most the same version of the component is
+        <listitem><para>At most the same version of the package is
         available or installed.</para></listitem>
 
       </varlistentry>
       
       <varlistentry><term><literal>></literal> <replaceable>version</replaceable></term>
 
-        <listitem><para>Only older versions of the component are
+        <listitem><para>Only older versions of the package are
         available or installed.</para></listitem>
 
       </varlistentry>
       
       <varlistentry><term><literal>- ?</literal></term>
 
-        <listitem><para>No version of the component is available or
+        <listitem><para>No version of the package is available or
         installed.</para></listitem>
 
       </varlistentry>
@@ -810,6 +983,14 @@ user environment elements, etc. -->
     
   </varlistentry>
 
+  <varlistentry><term><option>--meta</option></term>
+  
+    <listitem><para>Print all of the meta-attributes of the
+    derivation.  This option is only available with
+    <option>--xml</option>.</para></listitem>
+    
+  </varlistentry>
+
 </variablelist>
 
 </refsection>

doc/manual/nix-pack-closure.xml

@@ -1,82 +0,0 @@
-<refentry xmlns="http://docbook.org/ns/docbook"
-          xmlns:xlink="http://www.w3.org/1999/xlink"
-          xmlns:xi="http://www.w3.org/2001/XInclude">
-
-<refmeta>
-  <refentrytitle>nix-pack-closure</refentrytitle>
-  <manvolnum>1</manvolnum>
-  <refmiscinfo class="source">Nix</refmiscinfo>
-  <refmiscinfo class="version"><xi:include href="version.txt" parse="text"/></refmiscinfo>
-</refmeta>
-
-<refnamediv>
-  <refname>nix-pack-closure</refname>
-  <refpurpose>pack the closure of a store path into a single file that
-  can be unpacked with
-  <command>nix-unpack-closure</command></refpurpose>
-</refnamediv>
-
-<refsynopsisdiv>
-  <cmdsynopsis>
-    <command>nix-pack-closure</command>
-    <arg choice='plain' rep='repeat'><replaceable>paths</replaceable></arg>
-  </cmdsynopsis>
-</refsynopsisdiv>
-
-
-<refsection><title>Description</title>
-
-<para>The command <command>nix-pack-closure</command> packs the
-contents of the store paths <replaceable>paths</replaceable> and
-<emphasis>all their dependencies</emphasis> into a single file, which
-is written to standard output.  (That is, it
-<emphasis>serialises</emphasis> <replaceable>paths</replaceable>.)
-The output can then be unpacked into the Nix store of another machine
-using <command>nix-unpack-closure</command>.</para>
-
-<para>Together, <command>nix-pack-closure</command> and
-<command>nix-unpack-closure</command> provide a quick and easy way to
-deploy a package to a different machine.  However, as the output of
-<command>nix-pack-closure</command> tends to be rather large (since it
-contains all dependencies), it’s not very efficient.
-<command>nix-push</command> and <command>nix-pull</command> are more
-efficient, but are also a bit more cumbersome to use.</para>
-
-</refsection>
-
-
-<refsection><title>Examples</title>
-
-<para>To copy some instance of Subversion with all its dependencies to
-another machine:
-
-<screen>
-$ nix-pack-closure /nix/store/hj232g1r...-subversion-1.3.0 > svn.closure
-
-<lineannotation>Copy <!-- !!! <filename> -->svn.closure to the remote machine, then on the remote machine do:</lineannotation>
-$ nix-unpack-closure &lt; svn.closure</screen>
-
-</para>
-
-<para>Copy the program <command>azureus</command> with all its
-dependencies to the machine <literal>scratchy</literal>:
-
-<screen>
-$ nix-pack-closure $(which azureus) | ssh scratchy nix-unpack-closure</screen>
-    
-</para>
-
-<para>As a variation on the previous example, copy
-<command>azureus</command>, and also install it in the user’s profile
-on the target machine:
-
-<screen>
-$ nix-pack-closure $(which azureus) | ssh scratchy 'nix-env -i $(nix-unpack-closure)'</screen>
-
-</para>
- 
-
-</refsection>
-
-
-</refentry>

doc/manual/nix-store.xml

@@ -128,6 +128,7 @@ lrwxrwxrwx    1 ... 2005-03-13 21:10 /home/eelco/bla/result -> /nix/store/1r1134
     <arg choice='plain'><option>-r</option></arg>
   </group>
   <arg choice='plain' rep='repeat'><replaceable>paths</replaceable></arg>
+  <arg><option>--dry-run</option></arg>
 </cmdsynopsis>
 
 </refsection>
@@ -166,6 +167,11 @@ the specified store paths.  Realisation is a somewhat overloaded term:
 output.  (For non-derivations argument, the argument itself is
 printed.)</para>
 
+<para>If the <option>--dry-run</option> option is used, then
+<command>nix-store</command> will print on standard error a
+description of what packages would be built or downloaded, and then
+quit.</para>
+
 </refsection>
             
 
@@ -204,6 +210,10 @@ linkend="sec-nix-build"><command>nix-build</command></link> does.</para>
     <arg choice='plain'><option>--print-dead</option></arg>
     <arg choice='plain'><option>--delete</option></arg>
   </group>
+  <arg><option>--max-freed</option> <replaceable>bytes</replaceable></arg>
+  <arg><option>--max-links</option> <replaceable>nrlinks</replaceable></arg>
+  <arg><option>--max-atime</option> <replaceable>atime</replaceable></arg>
+  <arg><option>--use-atime</option></arg>
 </cmdsynopsis>
 
 </refsection>
@@ -258,7 +268,70 @@ the Nix store not reachable via file system references from a set of
 
 </variablelist>
 
-<para>The behaviour of the collector is influenced by the <link
+<para>By default, all unreachable paths are deleted.  The following
+options control what gets deleted and in what order:
+
+<variablelist>
+
+  <varlistentry><term><option>--max-freed</option> <replaceable>bytes</replaceable></term>
+  
+    <listitem><para>Keep deleting paths until at least
+    <replaceable>bytes</replaceable> bytes have been
+    deleted, then stop.</para></listitem>
+    
+  </varlistentry>
+
+  <varlistentry><term><option>--max-links</option> <replaceable>nrlinks</replaceable></term>
+  
+    <listitem><para>Keep deleting paths until the hard link count on
+    <filename>/nix/store</filename> is less than
+    <replaceable>nrlinks</replaceable>, then stop.  This is useful for
+    very large Nix stores on filesystems with a 32000 subdirectories
+    limit (like <literal>ext3</literal>).</para></listitem>
+    
+  </varlistentry>
+
+  <varlistentry><term><option>--max-atime</option> <replaceable>atime</replaceable></term>
+  
+    <listitem><para>Only delete a store path if its last-accessed time
+    is less than <replaceable>atime</replaceable>.  This allows you to
+    garbage-collect only packages that haven’t been used recently.
+    The time is expressed as the number of seconds in the Unix epoch,
+    i.e., since 1970-01-01 00:00:00 UTC.  An easy way to convert to
+    this format is <literal>date +%s -d "<replaceable>date
+    specification</replaceable>"</literal>.</para>
+
+    <para>For directories, the last-accessed time is the highest
+    last-accessed time of any regular file in the directory (or in any
+    of its subdirectories).  That is, the <literal>atime</literal>
+    field maintained by the filesystem is ignored for directories.
+    This is because operations such as rebuilding the
+    <command>locate</command> database tend to update the
+    <literal>atime</literal> values of all directories, so they’re not
+    a useful indicator of whether a package was recently used.</para>
+
+    <para>Note that <command>nix-store --optimise</command> reads all
+    regular files in the Nix store, and so causes all last-accessed
+    times to be set to the present time.  This makes
+    <option>--max-atime</option> ineffective (for a while at
+    least).</para></listitem>
+    
+  </varlistentry>
+
+  <varlistentry><term><option>--use-atime</option></term>
+
+    <listitem><para>Delete store paths in order of ascending
+    last-accessed time.  This is useful in conjunction with the other
+    options to delete only the least recently used
+    packages.</para></listitem>
+
+  </varlistentry>
+  
+</variablelist>
+
+</para>
+
+<para>The behaviour of the collector is also influenced by the <link
 linkend="conf-gc-keep-outputs"><literal>gc-keep-outputs</literal></link>
 and <link
 linkend="conf-gc-keep-derivations"><literal>gc-keep-derivations</literal></link>
@@ -284,6 +357,20 @@ deleting `/nix/store/kq82idx6g0nyzsp2s14gfsc38npai7lf-cairo-1.0.4.tar.gz.drv'
 
 </para>
 
+<para>To delete unreachable paths not accessed in the last two months:
+
+<screen>
+$ nix-store --gc -v --max-atime $(date +%s -d "2 months ago")</screen>
+
+</para>
+
+<para>To delete at least 100 MiBs of unreachable paths:
+
+<screen>
+$ nix-store --gc --max-freed $((100 * 1024 * 1024))</screen>
+
+</para>
+
 </refsection>
 
 
@@ -779,4 +866,222 @@ archive is read from standard input.</para>
 </refsection>
 
 
+<!--######################################################################-->
+
+<refsection xml:id='refsec-nix-store-export'><title>Operation <option>--export</option></title>
+
+<refsection>
+  <title>Synopsis</title>
+  <cmdsynopsis>
+    <command>nix-store</command>
+    <arg choice='plain'><option>--export</option></arg>
+    <arg choice='plain' rep='repeat'><replaceable>paths</replaceable></arg>
+  </cmdsynopsis>
+</refsection>
+
+<refsection><title>Description</title>
+            
+<para>The operation <option>--export</option> writes a serialisation
+of the specified store paths to standard output in a format that can
+be imported into another Nix store with <command
+linkend="refsec-nix-store-import">nix-store --import</command>.  This
+is like <command linkend="refsec-nix-store-dump">nix-store
+--dump</command>, except that the NAR archive produced by that command
+doesn’t contain the necessary meta-information to allow it to be
+imported into another Nix store (namely, the set of references of the
+path).</para>
+
+<para>This command does not produce a <emphasis>closure</emphasis> of
+the specified paths, so if a store path references other store paths
+that are missing in the target Nix store, the import will fail.  To
+copy a whole closure, do something like
+
+<screen>
+$ nix-store --export $(nix-store -qR <replaceable>paths</replaceable>) > out</screen>
+
+</para>
+
+<para>For an example of how <option>--export</option> and
+<option>--import</option> can be used, see the source of the <command
+linkend="sec-nix-copy-closure">nix-copy-closure</command>
+command.</para>
+
+</refsection>
+            
+
+</refsection>
+
+
+<!--######################################################################-->
+
+<refsection xml:id='refsec-nix-store-import'><title>Operation <option>--import</option></title>
+
+<refsection>
+  <title>Synopsis</title>
+  <cmdsynopsis>
+    <command>nix-store</command>
+    <arg choice='plain'><option>--import</option></arg>
+  </cmdsynopsis>
+</refsection>
+
+<refsection><title>Description</title>
+            
+<para>The operation <option>--export</option> reads a serialisation of
+a set of store paths produced by <command
+linkend="refsec-nix-store-export">nix-store --import</command> from
+standard input and adds those store paths to the Nix store.  Paths
+that already exist in the Nix store are ignored.  If a path refers to
+another path that doesn’t exist in the Nix store, the import
+fails.</para>
+
+</refsection>
+            
+
+</refsection>
+
+
+<!--######################################################################-->
+
+<refsection><title>Operation <option>--optimise</option></title>
+
+<refsection>
+  <title>Synopsis</title>
+  <cmdsynopsis>
+    <command>nix-store</command>
+    <arg choice='plain'><option>--optimise</option></arg>
+  </cmdsynopsis>
+</refsection>
+
+<refsection><title>Description</title>
+            
+<para>The operation <option>--optimise</option> reduces Nix store disk
+space usage by finding identical files in the store and hard-linking
+them to each other.  It typically reduces the size of the store by
+something like 25-35%.  Only regular files and symlinks are
+hard-linked in this manner.  Files are considered identical when they
+have the same NAR archive serialisation: that is, regular files must
+have the same contents and permission (executable or non-executable),
+and symlinks must have the same contents.</para>
+
+<para>After completion, or when the command is interrupted, a report
+on the achieved savings is printed on standard error.</para>
+
+<para>Use <option>-vv</option> or <option>-vvv</option> to get some
+progress indication.</para>
+
+</refsection>
+            
+<refsection><title>Example</title>
+
+<screen>
+$ nix-store --optimise
+hashing files in `/nix/store/qhqx7l2f1kmwihc9bnxs7rc159hsxnf3-gcc-4.1.1'
+<replaceable>...</replaceable>
+541838819 bytes (516.74 MiB) freed by hard-linking 54143 files;
+there are 114486 files with equal contents out of 215894 files in total
+</screen>
+
+</refsection>
+
+
+</refsection>
+
+
+<!--######################################################################-->
+
+<refsection><title>Operation <option>--read-log</option></title>
+
+<refsection>
+  <title>Synopsis</title>
+  <cmdsynopsis>
+    <command>nix-store</command>
+    <group choice='req'>
+      <arg choice='plain'><option>--read-log</option></arg>
+      <arg choice='plain'><option>-l</option></arg>
+    </group>
+    <arg choice='plain' rep='repeat'><replaceable>paths</replaceable></arg>
+  </cmdsynopsis>
+</refsection>
+
+<refsection><title>Description</title>
+            
+<para>The operation <option>--read-log</option> prints the build log
+of the specified store paths on standard output.  The build log is
+whatever the builder of a derivation wrote to standard output and
+standard error.  If a store path is not a derivation, the deriver of
+the store path is used.</para>
+
+<para>Build logs are kept in
+<filename>/nix/var/log/nix/drvs</filename>.  However, there is no
+guarantee that a build log is available for any particular store
+path.  For instance, if the path was downloaded as a pre-built binary
+through a substitute, then the log is unavailable.</para>
+
+</refsection>
+            
+<refsection><title>Example</title>
+
+<screen>
+$ nix-store -l $(which ktorrent)
+building /nix/store/dhc73pvzpnzxhdgpimsd9sw39di66ph1-ktorrent-2.2.1
+unpacking sources
+unpacking source archive /nix/store/p8n1jpqs27mgkjw07pb5269717nzf5f8-ktorrent-2.2.1.tar.gz
+ktorrent-2.2.1/
+ktorrent-2.2.1/NEWS
+<replaceable>...</replaceable>
+</screen>
+
+</refsection>
+
+
+</refsection>
+
+
+<!--######################################################################-->
+
+<refsection><title>Operation <option>--dump-db</option></title>
+
+<refsection>
+  <title>Synopsis</title>
+  <cmdsynopsis>
+    <command>nix-store</command>
+    <arg choice='plain'><option>--dump-db</option></arg>
+  </cmdsynopsis>
+</refsection>
+
+<refsection><title>Description</title>
+            
+<para>The operation <option>--dump-db</option> writes a dump of the
+Nix database to standard output.  It can be loaded into an empty Nix
+store using <option>--load-db</option>.  This is useful for making
+backups and when migrating to different database schemas.</para>
+
+</refsection>
+            
+</refsection>
+
+
+<!--######################################################################-->
+
+<refsection><title>Operation <option>--dump-db</option></title>
+
+<refsection>
+  <title>Synopsis</title>
+  <cmdsynopsis>
+    <command>nix-store</command>
+    <arg choice='plain'><option>--load-db</option></arg>
+  </cmdsynopsis>
+</refsection>
+
+<refsection><title>Description</title>
+            
+<para>The operation <option>--load-db</option> reads a dump of the Nix
+database created by <option>--dump-db</option> from standard input and
+loads it into the Nix database.</para>
+
+</refsection>
+            
+</refsection>
+
+
 </refentry>

doc/manual/nix-unpack-closure.xml

@@ -1,42 +0,0 @@
-<refentry xmlns="http://docbook.org/ns/docbook"
-          xmlns:xlink="http://www.w3.org/1999/xlink"
-          xmlns:xi="http://www.w3.org/2001/XInclude">
-
-<refmeta>
-  <refentrytitle>nix-unpack-closure</refentrytitle>
-  <manvolnum>1</manvolnum>
-  <refmiscinfo class="source">Nix</refmiscinfo>
-  <refmiscinfo class="version"><xi:include href="version.txt" parse="text"/></refmiscinfo>
-</refmeta>
-
-<refnamediv>
-  <refname>nix-unpack-closure</refname>
-  <refpurpose>unpack the closure of a store path created by <command>nix-pack-closure</command> into the Nix store</refpurpose>
-</refnamediv>
-
-<refsynopsisdiv>
-  <cmdsynopsis>
-    <command>nix-unpack-closure</command>
-  </cmdsynopsis>
-</refsynopsisdiv>
-
-
-<refsection><title>Description</title>
-
-<para>The command <command>nix-unpack-closure</command> unpacks the
-closure of a set of store paths created by
-<command>nix-pack-closure</command> into the local Nix store.  The
-closure is a single file read from standard input.  See the
-description of <command>nix-pack-closure</command> for details and
-examples.</para>
-
-<para>The top-level paths in the closure (i.e., the paths passed to
-the original <command>nix-pack-closure</command> call that created the
-closure) are printed on standard output.  These paths can be passed,
-for instance, to <literal>nix-env -i</literal> to install them into a
-user environment on the target machine.</para>
-
-</refsection>
-
-
-</refentry>

doc/manual/nix-worker.xml

@@ -0,0 +1,34 @@
+<refentry xmlns="http://docbook.org/ns/docbook"
+          xmlns:xlink="http://www.w3.org/1999/xlink"
+          xmlns:xi="http://www.w3.org/2001/XInclude">
+
+<refmeta>
+  <refentrytitle>nix-worker</refentrytitle>
+  <manvolnum>8</manvolnum>
+  <refmiscinfo class="source">Nix</refmiscinfo>
+  <refmiscinfo class="version"><xi:include href="version.txt" parse="text"/></refmiscinfo>
+</refmeta>
+
+<refnamediv>
+  <refname>nix-worker</refname>
+  <refpurpose>Nix multi-user support daemon</refpurpose>
+</refnamediv>
+
+<refsynopsisdiv>
+  <cmdsynopsis>
+    <command>nix-worker</command>
+    <arg choice="plain"><option>--daemon</option></arg>
+  </cmdsynopsis>
+</refsynopsisdiv>
+
+
+<refsection><title>Description</title>
+
+<para>The Nix daemon is necessary in multi-user Nix installations.  It
+performs build actions and other operations on the Nix store on behalf
+of unprivileged users.</para>
+
+
+</refsection>
+
+</refentry>

doc/manual/opt-common-syn.xml

@@ -13,6 +13,10 @@
   </group>
   <replaceable>number</replaceable>
 </arg>
+<arg>
+  <arg><option>--max-silent-time</option></arg>
+  <replaceable>number</replaceable>
+</arg>
 <arg><option>--keep-going</option></arg>
 <arg><option>-k</option></arg>
 <arg><option>--keep-failed</option></arg>

doc/manual/opt-common.xml

@@ -103,6 +103,17 @@
 </varlistentry>
 
 
+<varlistentry xml:id="opt-max-silent-time"><term><option>--max-silent-time</option></term>
+
+  <listitem><para>Sets the maximum number of seconds that a builder
+  can go without producing any data on standard output or standard
+  error.  The default is specified by the <link
+  linkend='conf-build-max-silent-time'><literal>build-max-silent-time</literal></link>
+  configuration setting.  <literal>0</literal> means no
+  time-out.</para></listitem>
+
+</varlistentry>
+
 <varlistentry><term><option>--keep-going</option></term>
   <term><option>-k</option></term>
 
@@ -257,6 +268,17 @@
 </varlistentry>
 
 
+<varlistentry><term><option>--argstr</option> <replaceable>name</replaceable> <replaceable>value</replaceable></term>
+
+  <listitem><para>This option is like <option>--arg</option>, only the
+  value is not a Nix expression but a string.  So instead of
+  <literal>--arg system \"i686-linux\"</literal> (the outer quotes are
+  to keep the shell happy) you can say <literal>--argstr system
+  i686-linux</literal>.</para></listitem>
+
+</varlistentry>
+
+
 <varlistentry xml:id="opt-attr"><term><option>--attr</option> / <option>-A</option>
 <replaceable>attrPath</replaceable></term>
 

doc/manual/opt-inst-syn.xml

@@ -0,0 +1,22 @@
+<nop xmlns="http://docbook.org/ns/docbook">
+  
+  <arg>
+    <group choice='req'>
+      <arg choice='plain'><option>--prebuilt-only</option></arg>
+      <arg choice='plain'><option>-b</option></arg>
+    </group>
+  </arg>
+  
+  <arg>
+    <group choice='req'>
+      <arg choice='plain'><option>--attr</option></arg>
+      <arg choice='plain'><option>-A</option></arg>
+    </group>
+  </arg>
+
+  <arg><option>--from-expression</option></arg>
+  <arg><option>-E</option></arg>
+    
+  <arg><option>--from-profile</option> <replaceable>path</replaceable></arg>
+
+</nop>

doc/manual/package-management.xml

@@ -6,9 +6,9 @@
 
 
 <para>This chapter discusses how to do package management with Nix,
-i.e., how to obtain, install, upgrade, and erase components.  This is
+i.e., how to obtain, install, upgrade, and erase packages.  This is
 the “user’s” perspective of the Nix system — people
-who want to <emphasis>create</emphasis> components should consult
+who want to <emphasis>create</emphasis> packages should consult
 <xref linkend='chap-writing-nix-expressions' />.</para>
 
 
@@ -16,8 +16,8 @@ who want to <emphasis>create</emphasis> components should consult
 
 <para>The main command for package management is <link
 linkend="sec-nix-env"><command>nix-env</command></link>.  You can use
-it to install, upgrade, and erase components, and to query what
-components are installed or are available for installation.</para>
+it to install, upgrade, and erase packages, and to query what
+packages are installed or are available for installation.</para>
 
 <para>In Nix, different users can have different “views”
 on the set of installed applications.  That is, there might be lots of
@@ -30,18 +30,18 @@ environment</emphasis>, which is just a directory tree consisting of
 symlinks to the files of the active applications.  </para>
 
 <para>Components are installed from a set of <emphasis>Nix
-expressions</emphasis> that tell Nix how to build those components,
+expressions</emphasis> that tell Nix how to build those packages,
 including, if necessary, their dependencies.  There is a collection of
 Nix expressions called the Nix Package collection that contains
-components ranging from basic development stuff such as GCC and Glibc,
+packages ranging from basic development stuff such as GCC and Glibc,
 to end-user applications like Mozilla Firefox.  (Nix is however not
 tied to the Nix Package collection; you could write your own Nix
 expressions based on it, or completely new ones.)  You can download
 the latest version from <link
-xlink:href='http://nix.cs.uu.nl/dist/nix' />.</para>
+xlink:href='http://nixos.org/releases/full-index-nixpkgs.html' />.</para>
 
 <para>Assuming that you have downloaded and unpacked a release of Nix
-Packages, you can view the set of available components in the release:
+Packages, you can view the set of available packages in the release:
 
 <screen>
 $ nix-env -qaf nixpkgs-<replaceable>version</replaceable> '*'
@@ -74,7 +74,7 @@ gcc-4.1.1</screen>
 </para>
 
 <para>It is also possible to see the <emphasis>status</emphasis> of
-available components, i.e., whether they are installed into the user
+available packages, i.e., whether they are installed into the user
 environment and/or present in the system:
 
 <screen>
@@ -86,24 +86,24 @@ IPS bison-1.875d
 ...</screen>
 
 The first character (<literal>I</literal>) indicates whether the
-component is installed in your current user environment.  The second
+package is installed in your current user environment.  The second
 (<literal>P</literal>) indicates whether it is present on your system
 (in which case installing it into your user environment would be a
 very quick operation).  The last one (<literal>S</literal>) indicates
 whether there is a so-called <emphasis>substitute</emphasis> for the
-component, which is Nix’s mechanism for doing binary deployment.  It
-just means that Nix knows that it can fetch a pre-built component from
+package, which is Nix’s mechanism for doing binary deployment.  It
+just means that Nix knows that it can fetch a pre-built package from
 somewhere (typically a network server) instead of building it
 locally.</para>
 
 <para>So now that we have a set of Nix expressions we can build the
-components contained in them.  This is done using <literal>nix-env
+packages contained in them.  This is done using <literal>nix-env
 -i</literal>.  For instance,
 
 <screen>
 $ nix-env -f nixpkgs-<replaceable>version</replaceable> -i subversion</screen>
 
-will install the component called <literal>subversion</literal> (which
+will install the package called <literal>subversion</literal> (which
 is, of course, the <link
 xlink:href='http://subversion.tigris.org/'>Subversion version
 management system</link>).</para>
@@ -112,21 +112,21 @@ management system</link>).</para>
 Subversion and all its dependencies.  This will take quite a while —
 typically an hour or two on modern machines.  Fortunately, there is a
 faster way (so do a Ctrl-C on that install operation!): you just need
-to tell Nix that pre-built binaries of all those components are
+to tell Nix that pre-built binaries of all those packages are
 available somewhere.  This is done using the
 <command>nix-pull</command> command, which must be supplied with a URL
 containing a <emphasis>manifest</emphasis> describing what binaries
 are available.  This URL should correspond to the Nix Packages release
 that you’re using.  For instance, if you obtained a release from <link
-xlink:href='http://nix.cs.uu.nl/dist/nix/nixpkgs-0.6pre1554/' />, then
-you should do:
+xlink:href='http://nixos.org/releases/nixpkgs/nixpkgs-0.12pre11712-4lrp7j8x'
+/>, then you should do:
 
 <screen>
-$ nix-pull http://nix.cs.uu.nl/dist/nix/nixpkgs-0.6pre1554/MANIFEST</screen>
+$ nix-pull http://nixos.org/releases/nixpkgs/nixpkgs-0.12pre11712-4lrp7j8x/MANIFEST</screen>
 
 If you then issue the installation command, it should start
 downloading binaries from <systemitem
-class='fqdomainname'>nix.cs.uu.nl</systemitem>, instead of building
+class='fqdomainname'>nixos.org</systemitem>, instead of building
 them from source.  This might still take a while since all
 dependencies must be downloaded, but on a reasonably fast connection
 such as an DSL line it’s on the order of a few minutes.</para>
@@ -153,7 +153,7 @@ expressions, use <parameter>-i</parameter> instead of
 <parameter>-u</parameter>; <parameter>-i</parameter> will remove
 whatever version is already installed.</para>
 
-<para>You can also upgrade all components for which there are newer
+<para>You can also upgrade all packages for which there are newer
 versions:
 
 <screen>
@@ -199,19 +199,19 @@ set.</para></footnote></para>
 implementing the ability to allow different users to have different
 configurations, and to do atomic upgrades and rollbacks.  To
 understand how they work, it’s useful to know a bit about how Nix
-works.  In Nix, components are stored in unique locations in the
+works.  In Nix, packages are stored in unique locations in the
 <emphasis>Nix store</emphasis> (typically,
 <filename>/nix/store</filename>).  For instance, a particular version
-of the Subversion component might be stored in a directory
+of the Subversion package might be stored in a directory
 <filename>/nix/store/dpmvp969yhdqs7lm2r1a3gng7pyq6vy4-subversion-1.1.3/</filename>,
 while another version might be stored in
 <filename>/nix/store/5mq2jcn36ldlmh93yj1n8s9c95pj7c5s-subversion-1.1.2</filename>.
 The long strings prefixed to the directory names are cryptographic
 hashes<footnote><para>160-bit truncations of SHA-256 hashes encoded in
 a base-32 notation, to be precise.</para></footnote> of
-<emphasis>all</emphasis> inputs involved in building the component —
+<emphasis>all</emphasis> inputs involved in building the package —
 sources, dependencies, compiler flags, and so on.  So if two
-components differ in any way, they end up in different locations in
+packages differ in any way, they end up in different locations in
 the file system, so they don’t interfere with each other.  <xref
 linkend='fig-user-environments' /> shows a part of a typical Nix
 store.</para>
@@ -231,12 +231,12 @@ $ /nix/store/dpmvp969yhdq...-subversion-1.1.3/bin/svn</screen>
 
 every time you want to run Subversion.  Of course we could set up the
 <envar>PATH</envar> environment variable to include the
-<filename>bin</filename> directory of every component we want to use,
+<filename>bin</filename> directory of every package we want to use,
 but this is not very convenient since changing <envar>PATH</envar>
 doesn’t take effect for already existing processes.  The solution Nix
 uses is to create directory trees of symlinks to
-<emphasis>activated</emphasis> components.  These are called
-<emphasis>user environments</emphasis> and they are components
+<emphasis>activated</emphasis> packages.  These are called
+<emphasis>user environments</emphasis> and they are packages
 themselves (though automatically generated by
 <command>nix-env</command>), so they too reside in the Nix store.  For
 instance, in <xref linkend='fig-user-environments' /> the user
@@ -285,8 +285,8 @@ operation, a new user environment and generation link are created
 based on the current one, and finally the <filename>default</filename>
 symlink is made to point at the new generation.  This last step is
 atomic on Unix, which explains how we can do atomic upgrades.  (Note
-that the building/installing of new components doesn’t interfere in
-any way with old components, since they are stored in different
+that the building/installing of new packages doesn’t interfere in
+any way with old packages, since they are stored in different
 locations in the Nix store.)</para>
 
 <para>If you find that you want to undo a <command>nix-env</command>
@@ -352,18 +352,18 @@ This will <emphasis>not</emphasis> change the
 
 <para><command>nix-env</command> operations such as upgrades
 (<option>-u</option>) and uninstall (<option>-e</option>) never
-actually delete components from the system.  All they do (as shown
+actually delete packages from the system.  All they do (as shown
 above) is to create a new user environment that no longer contains
-symlinks to the “deleted” components.</para>
+symlinks to the “deleted” packages.</para>
 
-<para>Of course, since disk space is not infinite, unused components
+<para>Of course, since disk space is not infinite, unused packages
 should be removed at some point.  You can do this by running the Nix
-garbage collector.  It will remove from the Nix store any component
+garbage collector.  It will remove from the Nix store any package
 not used (directly or indirectly) by any generation of any
 profile.</para>
 
 <para>Note however that as long as old generations reference a
-component, it will not be deleted.  After all, we wouldn’t be able to
+package, it will not be deleted.  After all, we wouldn’t be able to
 do a rollback otherwise.  So in order for garbage collection to be
 effective, you should also delete (some) old generations.  Of course,
 this should only be done if you are certain that you will not need to
@@ -458,7 +458,7 @@ URL.</para>
 <command>nix-channel --add</command>, e.g.,
 
 <screen>
-$ nix-channel --add http://nix.cs.uu.nl/dist/nix/channels-v3/nixpkgs-unstable</screen>
+$ nix-channel --add http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable</screen>
 
 subscribes you to a channel that always contains that latest version
 of the Nix Packages collection.  (Instead of
@@ -486,7 +486,7 @@ makes the union of each channel’s Nix expressions the default for
 <screen>
 $ nix-env -u '*'</screen>
 
-to upgrade all components in your profile to the latest versions
+to upgrade all packages in your profile to the latest versions
 available in the subscribed channels.</para>
 
 </section>
@@ -496,20 +496,19 @@ available in the subscribed channels.</para>
 
 <para>Often, when you want to install a specific package (e.g., from
 the <link
-xlink:href="http://nix.cs.uu.nl/dist/nix/nixpkgs-unstable-latest/">Nix
-Packages collection</link> or from our <link
-xlink:href='http://nix.cs.uu.nl/dist/'>release server</link>),
-subscribing to a channel is a bit cumbersome.  And channels don’t help
-you at all if you want to install an older version of a package than
-the one provided by the current contents of the channel, or a package
-that has been removed from the channel.  That’s when
-<emphasis>one-click installs</emphasis> come in handy: you can just go
-to the web page that contains the package, click on it, and it will be
-installed with all the necessary dependencies.</para>
+xlink:href="http://nixos.org/releases/nixpkgs/nixpkgs-unstable/">Nix
+Packages collection</link>), subscribing to a channel is a bit
+cumbersome.  And channels don’t help you at all if you want to install
+an older version of a package than the one provided by the current
+contents of the channel, or a package that has been removed from the
+channel.  That’s when <emphasis>one-click installs</emphasis> come in
+handy: you can just go to the web page that contains the package,
+click on it, and it will be installed with all the necessary
+dependencies.</para>
 
 <para>For instance, you can go to <link
-xlink:href="http://nix.cs.uu.nl/dist/nix/nixpkgs-unstable-latest/" />
-— or to any older release of Nix Packages — and click on any link for
+xlink:href="http://nixos.org/releases/nixpkgs/nixpkgs-unstable/" /> —
+or to any older release of Nix Packages — and click on any link for
 the individual packages for your platform (say, <link
 xlink:href='http://nix.cs.uu.nl/dist/nix/nixpkgs-0.10pre6622/pkgs/subversion-1.4.0-i686-linux.nixpkg'><literal>subversion-1.4.0</literal>
 for <literal>i686-linux</literal></link>).  The first time you do
@@ -529,4 +528,82 @@ linkend='sec-nix-install-package' /> for details.</para>
 </section>
 
 
+<section xml:id="sec-sharing-packages"><title>Sharing packages between machines</title>
+
+<para>Sometimes you want to copy a package from one machine to
+another.  Or, you want to install some packages and you know that
+another machine already has some or all of those packages or their
+dependencies.  In that case there are mechanisms to quickly copy
+packages between machines.</para>
+
+<para>The command <command
+linkend="sec-nix-copy-closure">nix-copy-closure</command> copies a Nix
+store path along with all its dependencies to or from another machine
+via the SSH protocol.  It doesn’t copy store paths that are already
+present on the target machine.  For example, the following command
+copies Firefox with all its dependencies:
+
+<screen>
+$ nix-copy-closure --to alice@itchy.example.org $(type -p firefox)</screen>
+
+See <xref linkend='sec-nix-copy-closure' /> for details.</para>
+
+<para>With <command linkend='refsec-nix-store-export'>nix-store
+--export</command> and <command
+linkend='refsec-nix-store-import'>nix-store --import</command> you can
+write the closure of a store path (that is, the path and all its
+dependencies) to a file, and then unpack that file into another Nix
+store.  For example,
+
+<screen>
+$ nix-store --export $(type -p firefox) > firefox.closure</screen>
+
+writes the closure of Firefox to a file.  You can then copy this file
+to another machine and install the closure:
+
+<screen>
+$ nix-store --import &lt; firefox.closure</screen>
+
+Any store paths in the closure that are already present in the target
+store are ignored.  It is also possible to pipe the export into
+another command, e.g. to copy and install a closure directly to/on
+another machine:
+
+<screen>
+$ nix-store --export $(type -p firefox) | bzip2 | \
+    ssh alice@itchy.example.org "bunzip2 | nix-store --import"</screen>
+
+But note that <command>nix-copy-closure</command> is generally more
+efficient in this example because it only copies paths that are not
+already present in the target Nix store.</para>
+
+<para>Finally, if you can mount the Nix store of a remote machine in
+your local filesystem, Nix can copy paths from the remote Nix store to
+the local Nix store <emphasis>on demand</emphasis>.  For instance,
+suppose that you mount a remote machine containing a Nix store via
+<command
+xlink:href="http://fuse.sourceforge.net/sshfs.html">sshfs</command>:
+
+<screen>
+$ sshfs alice@itchy.example.org:/ /mnt</screen>
+
+You should then set the <envar>NIX_OTHER_STORES</envar> environment
+variable to tell Nix about this remote Nix store:
+
+<screen>
+$ export NIX_OTHER_STORES=/mnt/nix</screen>
+
+Then if you do any Nix operation, e.g.
+
+<screen>
+$ nix-env -i firefox</screen>
+
+and Nix has to build a path that it sees is already present in
+<filename>/mnt/nix</filename>, then it will just copy from there
+instead of building it from source.</para>
+ 
+
+</section>
+
+
 </chapter>

doc/manual/quick-start.xml

@@ -11,7 +11,7 @@ to the following chapters.</para>
 <orderedlist>
 
 <listitem><para>Download a source tarball or RPM from <link
-xlink:href='http://www.cs.uu.nl/groups/ST/Trace/Nix'/>.  Build source
+xlink:href='http://nixos.org/'/>.  Build source
 distributions using the regular sequence:
         
 <screen>
@@ -22,8 +22,9 @@ $ make install <lineannotation>(as root)</lineannotation></screen>
 
 This will install Nix in <filename>/nix</filename>.  You shouldn't
 change the prefix if at all possible since that will make it
-impossible to use our pre-built components.  Alternatively, you could
-grab an RPM if you're on an RPM-based system.  You should also add
+impossible to use pre-built binaries from the Nixpkgs channel and
+other channels.  Alternatively, you could grab an RPM if you're on an
+RPM-based system.  You should also add
 <filename>/nix/etc/profile.d/nix.sh</filename> to your
 <filename>~/.bashrc</filename> (or some other login
 file).</para></listitem>
@@ -32,7 +33,7 @@ file).</para></listitem>
 
 <screen>
 $ nix-channel --add \
-    http://nix.cs.uu.nl/dist/nix/channels-v3/nixpkgs-unstable</screen>
+    http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable</screen>
 
 </para></listitem>
 
@@ -40,14 +41,14 @@ $ nix-channel --add \
 <screen>
 $ nix-channel --update</screen>
 
-Note that this in itself doesn't download any components, it just
+Note that this in itself doesn't download any packages, it just
 downloads the Nix expressions that build them and stores them
 somewhere (under <filename>~/.nix-defexpr</filename>, in case you're
 curious).  Also, it registers the fact that pre-built binaries are
 available remotely.</para></listitem>
 
-<listitem><para>See what installable components are currently
-available in the channel:
+<listitem><para>See what installable packages are currently available
+in the channel:
 
 <screen>
 $ nix-env -qa ’*’ <lineannotation>(mind the quotes!)</lineannotation>
@@ -59,13 +60,13 @@ libxslt-1.1.0
 
 </para></listitem>
 
-<listitem><para>Install some components from the channel:
+<listitem><para>Install some packages from the channel:
         
 <screen>
 $ nix-env -i hello firefox <replaceable>...</replaceable> </screen>
 
-This should download the pre-built components; it should not build
-them locally (if it does, something went wrong).</para></listitem>
+This should download pre-built packages; it should not build them
+locally (if it does, something went wrong).</para></listitem>
 
 <listitem><para>Test that they work:
 
@@ -92,8 +93,8 @@ $ nix-env -e hello</screen>
 $ nix-channel --update
 $ nix-env -u '*'</screen>
 
-The latter command will upgrade each installed component for which
-there is a “newer” version (as determined by comparing the version
+The latter command will upgrade each installed package for which there
+is a “newer” version (as determined by comparing the version
 numbers).</para></listitem>
 
 <listitem><para>You can also install specific packages directly from
@@ -107,7 +108,7 @@ appear asking you whether it’s okay to install the package.  Say
 installed.</para></listitem>
 
 <listitem><para>If you're unhappy with the result of a
-<command>nix-env</command> action (e.g., an upgraded component turned
+<command>nix-env</command> action (e.g., an upgraded package turned
 out not to work properly), you can go back:
 
 <screen>
@@ -124,7 +125,7 @@ $ nix-collect-garbage -d</screen>
 
 <!--
 The first command deletes old “generations” of your profile (making
-rollbacks impossible, but also making the components in those old
+rollbacks impossible, but also making the packages in those old
 generations available for garbage collection), while the second
 command actually deletes them.-->
 

doc/manual/release-notes.xml

@@ -8,115 +8,432 @@
 
 <!--==================================================================-->
 
-<section xml:id="ssec-relnotes-0.11"><title>Release 0.11 (TBA)</title>
+<section xml:id="ssec-relnotes-0.12"><title>Release 0.12 (November 20,
+2008)</title>
+
+<itemizedlist>
+
+  <listitem>
+    <para>Nix no longer uses Berkeley DB to store Nix store metadata.
+    The principal advantages of the new storage scheme are: it works
+    properly over decent implementations of NFS (allowing Nix stores
+    to be shared between multiple machines); no recovery is needed
+    when a Nix process crashes; no write access is needed for
+    read-only operations; no more running out of Berkeley DB locks on
+    certain operations.</para>
+
+    <para>You still need to compile Nix with Berkeley DB support if
+    you want Nix to automatically convert your old Nix store to the
+    new schema.  If you don’t need this, you can build Nix with the
+    <filename>configure</filename> option
+    <option>--disable-old-db-compat</option>.</para>
+
+    <para>After the automatic conversion to the new schema, you can
+    delete the old Berkeley DB files:
+
+    <screen>
+$ cd /nix/var/nix/db
+$ rm __db* log.* derivers references referrers reserved validpaths DB_CONFIG</screen>
+
+    The new metadata is stored in the directories
+    <filename>/nix/var/nix/db/info</filename> and
+    <filename>/nix/var/nix/db/referrer</filename>.  Though the
+    metadata is stored in human-readable plain-text files, they are
+    not intended to be human-editable, as Nix is rather strict about
+    the format.</para>
+
+    <para>The new storage schema may or may not require less disk
+    space than the Berkeley DB environment, mostly depending on the
+    cluster size of your file system.  With 1 KiB clusters (which
+    seems to be the <literal>ext3</literal> default nowadays) it
+    usually takes up much less space.</para>
+  </listitem>
+
+  <listitem><para>There is a new substituter that copies paths
+  directly from other (remote) Nix stores mounted somewhere in the
+  filesystem.  For instance, you can speed up an installation by
+  mounting some remote Nix store that already has the packages in
+  question via NFS or <literal>sshfs</literal>.  The environment
+  variable <envar>NIX_OTHER_STORES</envar> specifies the locations of
+  the remote Nix directories,
+  e.g. <literal>/mnt/remote-fs/nix</literal>.</para></listitem>
+
+  <listitem><para>New <command>nix-store</command> operations
+  <option>--dump-db</option> and <option>--load-db</option> to dump
+  and reload the Nix database.</para></listitem>
+
+  <listitem><para>The garbage collector has a number of new options to
+  allow only some of the garbage to be deleted.  The option
+  <option>--max-freed <replaceable>N</replaceable></option> tells the
+  collector to stop after at least <replaceable>N</replaceable> bytes
+  have been deleted.  The option <option>--max-links
+  <replaceable>N</replaceable></option> tells it to stop after the
+  link count on <filename>/nix/store</filename> has dropped below
+  <replaceable>N</replaceable>.  This is useful for very large Nix
+  stores on filesystems with a 32000 subdirectories limit (like
+  <literal>ext3</literal>).  The option <option>--use-atime</option>
+  causes store paths to be deleted in order of ascending last access
+  time.  This allows non-recently used stuff to be deleted.  The
+  option <option>--max-atime <replaceable>time</replaceable></option>
+  specifies an upper limit to the last accessed time of paths that may
+  be deleted.  For instance,
+
+    <screen>
+    $ nix-store --gc -v --max-atime $(date +%s -d "2 months ago")</screen>
+
+  deletes everything that hasn’t been accessed in two months.</para></listitem>
+
+  <listitem><para><command>nix-env</command> now uses optimistic
+  profile locking when performing an operation like installing or
+  upgrading, instead of setting an exclusive lock on the profile.
+  This allows multiple <command>nix-env -i / -u / -e</command>
+  operations on the same profile in parallel.  If a
+  <command>nix-env</command> operation sees at the end that the profile
+  was changed in the meantime by another process, it will just
+  restart.  This is generally cheap because the build results are
+  still in the Nix store.</para></listitem>
+
+  <listitem><para>The option <option>--dry-run</option> is now
+  supported by <command>nix-store -r</command> and
+  <command>nix-build</command>.</para></listitem>
+
+  <listitem><para>The information previously shown by
+  <option>--dry-run</option> (i.e., which derivations will be built
+  and which paths will be substituted) is now always shown by
+  <command>nix-env</command>, <command>nix-store -r</command> and
+  <command>nix-build</command>.  The total download size of
+  substitutable paths is now also shown.  For instance, a build will
+  show something like
+
+    <screen>
+the following derivations will be built:
+  /nix/store/129sbxnk5n466zg6r1qmq1xjv9zymyy7-activate-configuration.sh.drv
+  /nix/store/7mzy971rdm8l566ch8hgxaf89x7lr7ik-upstart-jobs.drv
+  ...
+the following paths will be downloaded/copied (30.02 MiB):
+  /nix/store/4m8pvgy2dcjgppf5b4cj5l6wyshjhalj-samba-3.2.4
+  /nix/store/7h1kwcj29ip8vk26rhmx6bfjraxp0g4l-libunwind-0.98.6
+  ...</screen>      
+  
+  </para></listitem>
+
+  <listitem><para>Language features:
+
+    <itemizedlist>
+
+      <listitem><para>@-patterns as in Haskell.  For instance, in a
+      function definition
+
+      <programlisting>f = args @ {x, y, z}: <replaceable>...</replaceable>;</programlisting>
+
+      <varname>args</varname> refers to the argument as a whole, which
+      is further pattern-matched against the attribute set pattern
+      <literal>{x, y, z}</literal>.</para></listitem>
+
+      <listitem><para>“<literal>...</literal>” (ellipsis) patterns.
+      An attribute set pattern can now say <literal>...</literal>  at
+      the end of the attribute name list to specify that the function
+      takes <emphasis>at least</emphasis> the listed attributes, while
+      ignoring additional attributes.  For instance,
+
+      <programlisting>{stdenv, fetchurl, fuse, ...}: <replaceable>...</replaceable></programlisting>
+
+      defines a function that accepts any attribute set that includes
+      at least the three listed attributes.</para></listitem>
+
+      <listitem><para>New primops:
+      <varname>builtins.parseDrvName</varname> (split a package name
+      string like <literal>"nix-0.12pre12876"</literal> into its name
+      and version components, e.g. <literal>"nix"</literal> and
+      <literal>"0.12pre12876"</literal>),
+      <varname>builtins.compareVersions</varname> (compare two version
+      strings using the same algorithm that <command>nix-env</command>
+      uses), <varname>builtins.length</varname> (efficiently compute
+      the length of a list), <varname>builtins.mul</varname> (integer
+      multiplication), <varname>builtins.div</varname> (integer
+      division).
+      <!-- <varname>builtins.genericClosure</varname> -->
+      </para></listitem>
+      
+    </itemizedlist>
+
+  </para></listitem>
+
+  <listitem><para><command>nix-prefetch-url</command> now supports
+  <literal>mirror://</literal> URLs, provided that the environment
+  variable <envar>NIXPKGS_ALL</envar> points at a Nixpkgs
+  tree.</para></listitem>
+
+  <listitem><para>Removed the commands
+  <command>nix-pack-closure</command> and
+  <command>nix-unpack-closure</command>.   You can do almost the same
+  thing but much more efficiently by doing <literal>nix-store --export
+  $(nix-store -qR <replaceable>paths</replaceable>) > closure</literal> and
+  <literal>nix-store --import &lt;
+  closure</literal>.</para></listitem>
+
+  <listitem><para>Lots of bug fixes, including a big performance bug in
+  the handling of <literal>with</literal>-expressions.</para></listitem>
+
+</itemizedlist>
+
+</section>
+
+
+<!--==================================================================-->
+
+<section xml:id="ssec-relnotes-0.11"><title>Release 0.11 (December 31,
+2007)</title>
+
+<para>Nix 0.11 has many improvements over the previous stable release.
+The most important improvement is secure multi-user support.  It also
+features many usability enhancements and language extensions, many of
+them prompted by NixOS, the purely functional Linux distribution based
+on Nix.  Here is an (incomplete) list:</para>
+
 
 <itemizedlist>
 
 
-  <listitem><para>TODO: multi-user support.  The old setuid method for
-  sharing a store between multiple users has been
-  removed.</para></listitem>
+  <listitem><para>Secure multi-user support.  A single Nix store can
+  now be shared between multiple (possible untrusted) users.  This is
+  an important feature for NixOS, where it allows non-root users to
+  install software.  The old setuid method for sharing a store between
+  multiple users has been removed.  Details for setting up a
+  multi-user store can be found in the manual.</para></listitem>
 
 
   <listitem><para>The new command <command>nix-copy-closure</command>
   gives you an easy and efficient way to exchange software between
   machines.  It copies the missing parts of the closure of a set of
-  store path to or from a remote machine.</para></listitem>
+  store path to or from a remote machine via
+  <command>ssh</command>.</para></listitem>
 
 
-  <listitem><para><command>nix-prefetch-url</command> now by default
-  computes the SHA-256 hash of the file instead of the MD5 hash.  In
-  calls to <function>fetchurl</function> you should pass an
-  <literal>sha256</literal> attribute instead of
-  <literal>md5</literal>.  You can pass either a hexadecimal or a
-  base-32 encoding of the hash.</para></listitem>
-
-  
-  <listitem><para><command>nix-store</command> has a new operation
-  <option>--read-log</option> (<option>-l</option>)
-  <parameter>paths</parameter> that shows the build log of the given
-  paths.</para></listitem>
-
-  
-  <listitem><para>TODO: <varname>allowedReferences</varname> for
-  checking the set of references in the output of a
-  derivation.</para></listitem>
+  <listitem><para>A new kind of string literal: strings between double
+  single-quotes (<literal>''</literal>) have indentation
+  “intelligently” removed.  This allows large strings (such as shell
+  scripts or configuration file fragments in NixOS) to cleanly follow
+  the indentation of the surrounding expression.  It also requires
+  much less escaping, since <literal>''</literal> is less common in
+  most languages than <literal>"</literal>.</para></listitem>
 
 
-  <listitem><para>TODO: semantic cleanups of string concatenation
-  etc. (mostly in r6740).</para></listitem>
-
-
-  <listitem><para>TODO: now using Berkeley DB 4.5.</para></listitem>
-
-
-  <listitem><para>TODO: option <option>--reregister</option> in
-  <command>nix-store --register-validity</command>.</para></listitem>
-
-
-  <listitem><para>TODO: magic <varname>exportReferencesGraph</varname>
-  attribute.</para></listitem>
-
-
-  <listitem><para>TODO: option <option>--max-silent-time</option>,
-  configuration setting
-  <literal>build-max-silent-time</literal>.</para></listitem>
-
-
-  <listitem><para>TODO: <command>nix-env</command>
-  <option>--set</option>.</para></listitem>
+  <listitem><para><command>nix-env</command> <option>--set</option>
+  modifies the current generation of a profile so that it contains
+  exactly the specified derivation, and nothing else.  For example,
+  <literal>nix-env -p /nix/var/nix/profiles/browser --set
+  firefox</literal> lets the profile named
+  <filename>browser</filename> contain just Firefox.</para></listitem>
   
 
-  <listitem><para>TODO: <option>--argstr</option>.</para></listitem>
-
-
-  <listitem><para>TODO: <command>nix-env</command> now maintains meta
-  info about installed packages in user environments.  <option>-q
-  --xml --meta</option> to show all meta info.</para></listitem>
+  <listitem><para><command>nix-env</command> now maintains
+  meta-information about installed packages in profiles.  The
+  meta-information is the contents of the <varname>meta</varname>
+  attribute of derivations, such as <varname>description</varname> or
+  <varname>homepage</varname>.  The command <literal>nix-env -q --xml
+  --meta</literal> shows all meta-information.</para></listitem>
 
   
-  <listitem><para>TODO: <command>nix-env</command>
-  <option>--set-flag</option>.  Specific flags:
-  <literal>active</literal>, <literal>priority</literal>,
-  <literal>keep</literal>.</para></listitem>
+  <listitem><para><command>nix-env</command> now uses the
+  <varname>meta.priority</varname> attribute of derivations to resolve
+  filename collisions between packages.  Lower priority values denote
+  a higher priority.  For instance, the GCC wrapper package and the
+  Binutils package in Nixpkgs both have a file
+  <filename>bin/ld</filename>, so previously if you tried to install
+  both you would get a collision.  Now, on the other hand, the GCC
+  wrapper declares a higher priority than Binutils, so the former’s
+  <filename>bin/ld</filename> is symlinked in the user
+  environment.</para></listitem>
+
+
+  <listitem><para><command>nix-env -i / -u</command>: instead of
+  breaking package ties by version, break them by priority and version
+  number.  That is, if there are multiple packages with the same name,
+  then pick the package with the highest priority, and only use the
+  version if there are multiple packages with the same
+  priority.</para>
+
+  <para>This makes it possible to mark specific versions/variant in
+  Nixpkgs more or less desirable than others.  A typical example would
+  be a beta version of some package (e.g.,
+  <literal>gcc-4.2.0rc1</literal>) which should not be installed even
+  though it is the highest version, except when it is explicitly
+  selected (e.g., <literal>nix-env -i
+  gcc-4.2.0rc1</literal>).</para></listitem>
+
+
+  <listitem><para><command>nix-env --set-flag</command> allows meta
+  attributes of installed packages to be modified.  There are several
+  attributes that can be usefully modified, because they affect the
+  behaviour of <command>nix-env</command> or the user environment
+  build script:
+
+    <itemizedlist>
+
+      <listitem><para><varname>meta.priority</varname> can be changed
+      to resolve filename clashes (see above).</para></listitem>
+
+      <listitem><para><varname>meta.keep</varname> can be set to
+      <literal>true</literal> to prevent the package from being
+      upgraded or replaced.  Useful if you want to hang on to an older
+      version of a package.</para></listitem>
+
+      <listitem><para><varname>meta.active</varname> can be set to
+      <literal>false</literal> to “disable” the package.  That is, no
+      symlinks will be generated to the files of the package, but it
+      remains part of the profile (so it won’t be garbage-collected).
+      Set it back to <literal>true</literal> to re-enable the
+      package.</para></listitem>
+
+    </itemizedlist>
+
+  </para></listitem>
 
   
-  <listitem><para>TODO: <command>nix-env</command> <option>-i</option>
-  / <option>-u</option> take package priorities into
-  account.</para></listitem>
-  
-
   <listitem><para><command>nix-env -q</command> now has a flag
   <option>--prebuilt-only</option> (<option>-b</option>) that causes
   <command>nix-env</command> to show only those derivations whose
   output is already in the Nix store or that can be substituted (i.e.,
   downloaded from somewhere).  In other words, it shows the packages
   that can be installed “quickly”, i.e., don’t need to be built from
-  source.</para></listitem>
+  source.  The <option>-b</option> flag is also available in
+  <command>nix-env -i</command> and <command>nix-env -u</command> to
+  filter out derivations for which no pre-built binary is
+  available.</para></listitem>
   
 
-  <listitem><para>TODO: new built-ins
-  <function>builtins.attrNames</function>,
-  <function>builtins.filterSource</function>,
-  <function>builtins.sub</function>,
-  <function>builtins.stringLength</function>,
-  <function>builtins.substring</function>.</para></listitem>
+  <listitem><para>The new option <option>--argstr</option> (in
+  <command>nix-env</command>, <command>nix-instantiate</command> and
+  <command>nix-build</command>) is like <option>--arg</option>, except
+  that the value is a string.  For example, <literal>--argstr system
+  i686-linux</literal> is equivalent to <literal>--arg system
+  \"i686-linux\"</literal> (note that <option>--argstr</option>
+  prevents annoying quoting around shell arguments).</para></listitem>
 
 
-  <listitem><para>TODO: each subscribed channel is its own attribute
-  in the top-level expression generated for the channel, this allows
-  disambiguation (<command>nix-env -qaA</command>).</para></listitem>
+  <listitem><para><command>nix-store</command> has a new operation
+  <option>--read-log</option> (<option>-l</option>)
+  <parameter>paths</parameter> that shows the build log of the given
+  paths.</para></listitem>
+
+  
+  <!--
+  <listitem><para>TODO: semantic cleanups of string concatenation
+  etc. (mostly in r6740).</para></listitem>
+  -->
 
 
-  <listitem><para>TODO: substitutes table is gone, registering
-  substitutes is now much faster.</para></listitem>
+  <listitem><para>Nix now uses Berkeley DB 4.5.  The database is
+  upgraded automatically, but you should be careful not to use old
+  versions of Nix that still use Berkeley DB 4.4.</para></listitem>
+
+
+  <!-- foo
+  <listitem><para>TODO: option <option>- -reregister</option> in
+  <command>nix-store - -register-validity</command>.</para></listitem>
+  -->
+
+
+  <listitem><para>The option <option>--max-silent-time</option>
+  (corresponding to the configuration setting
+  <literal>build-max-silent-time</literal>) allows you to set a
+  timeout on builds — if a build produces no output on
+  <literal>stdout</literal> or <literal>stderr</literal> for the given
+  number of seconds, it is terminated.  This is useful for recovering
+  automatically from builds that are stuck in an infinite
+  loop.</para></listitem>
+
+
+  <listitem><para><command>nix-channel</command>: each subscribed
+  channel is its own attribute in the top-level expression generated
+  for the channel.  This allows disambiguation (e.g. <literal>nix-env
+  -i -A nixpkgs_unstable.firefox</literal>).</para></listitem>
+
+
+  <listitem><para>The substitutes table has been removed from the
+  database.  This makes operations such as <command>nix-pull</command>
+  and <command>nix-channel --update</command> much, much
+  faster.</para></listitem>
+
+
+  <listitem><para><command>nix-pull</command> now supports
+  bzip2-compressed manifests.  This speeds up
+  channels.</para></listitem>
 
 
   <listitem><para><command>nix-prefetch-url</command> now has a
   limited form of caching.  This is used by
   <command>nix-channel</command> to prevent unnecessary downloads when
   the channel hasn’t changed.</para></listitem>
+
+
+  <listitem><para><command>nix-prefetch-url</command> now by default
+  computes the SHA-256 hash of the file instead of the MD5 hash.  In
+  calls to <function>fetchurl</function> you should pass the
+  <literal>sha256</literal> attribute instead of
+  <literal>md5</literal>.  You can pass either a hexadecimal or a
+  base-32 encoding of the hash.</para></listitem>
+
   
+  <listitem><para>Nix can now perform builds in an automatically
+  generated “chroot”.  This prevents a builder from accessing stuff
+  outside of the Nix store, and thus helps ensure purity.  This is an
+  experimental feature.</para></listitem>
+  
+
+  <listitem><para>The new command <command>nix-store
+  --optimise</command> reduces Nix store disk space usage by finding
+  identical files in the store and hard-linking them to each other.
+  It typically reduces the size of the store by something like
+  25-35%.</para></listitem>
+
+  
+  <listitem><para><filename>~/.nix-defexpr</filename> can now be a
+  directory, in which case the Nix expressions in that directory are
+  combined into an attribute set, with the file names used as the
+  names of the attributes.  The command <command>nix-env
+  --import</command> (which set the
+  <filename>~/.nix-defexpr</filename> symlink) is
+  removed.</para></listitem>
+
+
+  <listitem><para>Derivations can specify the new special attribute
+  <varname>allowedReferences</varname> to enforce that the references
+  in the output of a derivation are a subset of a declared set of
+  paths.  For example, if <varname>allowedReferences</varname> is an
+  empty list, then the output must not have any references.  This is
+  used in NixOS to check that generated files such as initial ramdisks
+  for booting Linux don’t have any dependencies.</para></listitem>
+
+
+  <listitem><para>The new attribute
+  <varname>exportReferencesGraph</varname> allows builders access to
+  the references graph of their inputs.  This is used in NixOS for
+  tasks such as generating ISO-9660 images that contain a Nix store
+  populated with the closure of certain paths.</para></listitem>
+
+
+  <listitem><para>Fixed-output derivations (like
+  <function>fetchurl</function>) can define the attribute
+  <varname>impureEnvVars</varname> to allow external environment
+  variables to be passed to builders.  This is used in Nixpkgs to
+  support proxy configuration, among other things.</para></listitem>
+
+
+  <listitem><para>Several new built-in functions:
+  <function>builtins.attrNames</function>,
+  <function>builtins.filterSource</function>,
+  <function>builtins.isAttrs</function>,
+  <function>builtins.isFunction</function>,
+  <function>builtins.listToAttrs</function>,
+  <function>builtins.stringLength</function>,
+  <function>builtins.sub</function>,
+  <function>builtins.substring</function>,
+  <function>throw</function>,
+  <function>builtins.trace</function>,
+  <function>builtins.readFile</function>.</para></listitem>
+
 
 </itemizedlist>
 

doc/manual/style.css

@@ -46,6 +46,11 @@ h3 /* subsections */
     font-size: 125%;
 }
 
+div.simplesect h2
+{
+    font-size: 110%;
+}
+
 div.appendix h3
 {
     font-size: 150%;

doc/manual/troubleshooting.xml

@@ -4,78 +4,9 @@
 <title>Troubleshooting</title>
 
 
-<para>This section provides solutions for some common problems.</para>
-
-
-<section><title>Berkeley DB: <quote>Cannot allocate memory</quote></title>
-
-<para>Symptom: Nix operations (in particular the
-<command>nix-store</command> operations <option>--gc</option>,
-<option>--verify</option>, and <option>--clear-substitutes</option> —
-the latter being called by <command>nix-channel --update</command>)
-failing:
-
-<screen>
-$ nix-store --verify
-error: Db::del: Cannot allocate memory</screen>
-
-</para>
-
-<para>Possible solution: make sure that no Nix processes are running,
-then do:
-
-<screen>
-$ cd /nix/var/nix/db
-$ rm __db.00*</screen>
-
-</para>
-
-</section>
-
-
-<section><title>Berkeley DB gives weird error messages</title>
-
-<para>Symptom: you get error messages such as
-
-<screen>
-Berkeley DB message: Finding last valid log LSN: file: 1 offset 28
-Berkeley DB error: file validpaths (meta pgno = 0) has LSN [483][34721].
-Berkeley DB error: end of log is [1][28]
-Berkeley DB error: /nix/var/nix/db/validpaths: unexpected file type or format</screen>
-
-or other weird Berkeley DB errors, and they don’t go away (i.e.,
-automatic recovery doesn’t work).  This may be the case after a system
-crash.</para>
-
-<para>Solution: first try to run <command>db_recover</command> and
-then <link linkend='refsec-nix-store-verify'><command>nix-store
---verify</command></link>:
-
-<screen>
-$ db_recover -h /nix/var/nix/db
-$ nix-store --verify</screen>
-
-(Make sure that you have the right version of
-<command>db_recover</command>, namely, Berkeley DB 4.4 for Nix 0.10,
-and 4.5 for Nix 0.11.)</para>
-
-<para>If that doesn’t work, it’s time to bring out the big guns:
-
-<screen>
-$ cd /nix/var/nix
-$ cp -pr db db-backup  <lineannotation>(making a backup just in case)</lineannotation>
-$ cd db
-$ rm __db.* log*  <lineannotation>(removing the Berkeley DB environment)</lineannotation>
-$ mkdir tmp
-$ for i in *; do db_dump $i | (cd tmp &amp;&amp; db_load $i); done 
-<lineannotation>(ignore error messages about non-database files like “reserved”)</lineannotation>
-$ mv tmp/* .
-$ nix-store --verify</screen>
-
-</para>
-
-</section>
-
+<para>This section provides solutions for some common problems.  See
+the <link xlink:href="http://bugs.strategoxt.org/browse/NIX">Nix
+bug tracker</link> for a list of currently known issues.</para>
 
 
 <section><title>Collisions in <command>nix-env</command></title>
@@ -145,7 +76,8 @@ Furthermore, the <literal>st_nlink</literal> field of the
 <para>This only happens on very large Nix installations (such as build
 machines).</para>
 
-<para>Quick solution: run the garbage collector.</para>
+<para>Quick solution: run the garbage collector.  You may want to use
+the <option>--max-links</option> option.</para>
 
 <para>Real solution: put the Nix store on a file system that supports
 more than 32,000 subdirectories per directory, such as ReiserFS.

externals/Makefile.am

@@ -2,6 +2,8 @@
 
 DB = db-4.5.20
 
+if OLD_DB_COMPAT
+
 $(DB).tar.gz:
 	@echo "Nix requires Berkeley DB to build."
 	@echo "Please download version 4.5.20 from"
@@ -32,6 +34,12 @@ build-db: have-db
 	touch build-db
 endif
 
+else
+
+build-db:
+
+endif
+
 
 # CWI ATerm
 
@@ -67,12 +75,12 @@ endif
 
 # bzip2
 
-BZIP2 = bzip2-1.0.4
+BZIP2 = bzip2-1.0.5
 
 $(BZIP2).tar.gz:
 	@echo "Nix requires bzip2 to build."
-	@echo "Please download version 1.0.4 from"
-	@echo "  http://www.bzip.org/1.0.4/bzip2-1.0.4.tar.gz"
+	@echo "Please download version 1.0.5 from"
+	@echo "  http://www.bzip.org/1.0.5/bzip2-1.0.5.tar.gz"
 	@echo "and place it in the externals/ directory."
 	false
 
@@ -105,5 +113,5 @@ EXTRA_DIST = $(DB).tar.gz $(ATERM).tar.bz2 $(BZIP2).tar.gz \
   bdb-cygwin.patch
 
 ext-clean:
-	$(RM) -f have-db build-db have-aterm build-aterm
+	$(RM) -f have-db build-db have-aterm build-aterm have-bzip2 build-bzip2
 	$(RM) -rf $(DB) $(ATERM) $(BZIP2)

misc/vim/syntax/nix.vim

@@ -0,0 +1,35 @@
+" Vim syntax file
+" Language:	nix
+" Maintainer:	Marc Weber <marco-oweber@gmx.de>
+"               Modify and commit if you feel that way
+" Last Change:	2007 Dec
+
+" Quit when a (custom) syntax file was already loaded
+if exists("b:current_syntax")
+  finish
+endif
+
+syn keyword	nixKeyword	let throw inherit import true false null with
+syn keyword	nixConditional	if else then
+syn keyword     nixBrace        ( ) { } =
+syn keyword     nixBuiltin         __currentSystem __currentTime __isFunction __getEnv __trace __toPath __pathExists 
+  \ __readFile __toXML __toFile __filterSource __attrNames __getAttr __hasAttr __isAttrs __listToAttrs __isList 
+  \ __head __tail __add __sub __lessThan __substring __stringLength
+
+syn match nixAttr "\w\+\ze\s*="
+syn match nixFuncArg "\zs\w\+\ze\s*:"
+syn region nixStringParam start=+\${+ end=+}+
+syn region nixMultiLineComment start=+/\*+ skip=+\\"+ end=+\*/+
+syn match  nixEndOfLineComment "#.*$"
+syn region nixString      start=+"+ skip=+\\"+ end=+"+ contains=nixStringParam
+
+hi def link nixKeyword       Keyword
+hi def link nixConditional   Conditional
+hi def link nixBrace         Special
+hi def link nixString        String
+hi def link nixBuiltin       Special
+hi def link nixStringParam   Macro
+hi def link nixMultiLineComment Comment
+hi def link nixEndOfLineComment Comment
+hi def link nixAttr        Identifier
+hi def link nixFuncArg     Identifier

nix.conf.example

@@ -29,25 +29,6 @@
 #gc-keep-derivations = true
 
 
-### Option `gc-reserved-space'
-#
-# This option specifies how much space should be reserved in normal
-# use so that the garbage collector can run succesfully.  Since the
-# garbage collector must perform Berkeley DB transactions, it needs
-# some disk space for itself.  However, when the disk is full, this
-# space is not available, so the collector would not be able to run
-# precisely when it is most needed.
-#
-# For this reason, when Nix is run, it allocates a file
-# /nix/var/nix/db/reserved of the size specified by this option.  When
-# the garbage collector is run, this file is deleted before the
-# Berkeley DB environment is opened.  This should give it enough room
-# to proceed.
-#
-# The default is "1048576" (1 MiB).
-#gc-reserved-space = 1048576
-
-
 ### Option `env-keep-derivations'
 #
 # If `false' (default), derivations are not stored in Nix user
@@ -80,7 +61,7 @@
 
 ### Option `build-max-silent-time'
 #
-# This option defines the maximum number of seconds that builder can
+# This option defines the maximum number of seconds that a builder can
 # go without producing any data on standard output or standard error.
 # This is useful (for instance in a automated build system) to catch
 # builds that are stuck in an infinite loop, or to catch remote builds
@@ -135,6 +116,44 @@
 #build-users-group =
 
 
+### Option `build-use-chroot'
+#
+# If set to `true', builds will be performed in a chroot environment,
+# i.e., the build will be isolated from the normal file system
+# hierarchy and will only see the Nix store, the temporary build
+# directory, and the directories configured with the
+# `build-chroot-dirs' option (such as /proc and /dev).  This is useful
+# to prevent undeclared dependencies on files in directories such as
+# /usr/bin.
+#
+# The use of a chroot requires that Nix is run as root (but you can
+# still use the "build users" feature to perform builds under
+# different users than root).  Currently, chroot builds only work on
+# Linux because Nix uses "bind mounts" to make the Nix store and other
+# directories available inside the chroot.
+#
+# The default is `false'.
+#
+# Example:
+#   build-use-chroot = true
+#build-use-chroot = false
+
+
+### Option `build-chroot-dirs'
+#
+# When builds are performed in a chroot environment, Nix will mount
+# (using `mount --bind' on Linux) some directories from the normal
+# file system hierarchy inside the chroot.  These are the Nix store,
+# the temporary build directory (usually /tmp/nix-<pid>-<number>) and
+# the directories listed here.  The default is "/dev /dev/pts /proc".
+# Files in /dev (such as /dev/null) are needed by many builds, and
+# some files in /proc may also be needed occasionally.
+#
+# Example:
+#   build-use-chroot = /dev /proc /bin
+#build-chroot-dirs = /dev /dev/pts /proc
+
+
 ### Option `system'
 #
 # This option specifies the canonical Nix system name of the current

nix.spec.in

@@ -13,11 +13,10 @@ Version: @version@
 Release: 1
 License: GPL
 Group: Software Deployment
-URL: http://nix.cs.uu.nl/
+URL: http://nixos.org/
 Source0: %{name}-@version@.tar.bz2
 BuildRoot: %{_tmppath}/%{name}-%{version}-buildroot
-%define _prefix /nix
-Prefix: %{_prefix}
+Prefix: /usr
 Requires: /usr/bin/perl
 Requires: curl
 
@@ -47,14 +46,14 @@ if test -n "%{enable_setuid}"; then
         extraFlags="$extraFlags --with-nix-group=%{nix_group}"
     fi
 fi
-./configure --prefix=%{_prefix} $extraFlags
+./configure --prefix=%{_prefix} --sysconfdir=/etc $extraFlags
 make
 make check
 
 %install
 rm -rf $RPM_BUILD_ROOT
 make DESTDIR=$RPM_BUILD_ROOT install
-rm $RPM_BUILD_ROOT/%{_prefix}/etc/nix/nix.conf
+rm $RPM_BUILD_ROOT/etc/nix/nix.conf
 strip $RPM_BUILD_ROOT/%{_prefix}/bin/* || true
 
 %clean
@@ -76,10 +75,9 @@ fi
 %{_prefix}/lib
 %{_prefix}/libexec
 %{_prefix}/include
-%{_prefix}/var
 %{_prefix}/share
-%{_prefix}/store
+/etc/profile.d/nix.sh
+/nix/var
+/nix/store
 %config
-%{_prefix}/etc
-#%doc
-#%{_prefix}/share/nix/manual
+/etc/nix

scripts/Makefile.am

@@ -1,22 +1,26 @@
 bin_SCRIPTS = nix-collect-garbage \
   nix-pull nix-push nix-prefetch-url \
   nix-install-package nix-channel nix-build \
-  nix-pack-closure nix-unpack-closure \
-  nix-copy-closure
+  nix-copy-closure 
 
-noinst_SCRIPTS = nix-profile.sh generate-patches.pl find-runtime-roots.pl
+noinst_SCRIPTS = nix-profile.sh generate-patches.pl \
+  find-runtime-roots.pl build-remote.pl nix-reduce-build \
+  copy-from-other-stores.pl nix-http-export.cgi
 
 nix-pull nix-push: readmanifest.pm readconfig.pm download-using-manifests.pl
 
-install-exec-local: readmanifest.pm download-using-manifests.pl find-runtime-roots.pl
+install-exec-local: readmanifest.pm download-using-manifests.pl copy-from-other-stores.pl find-runtime-roots.pl
 	$(INSTALL) -d $(DESTDIR)$(sysconfdir)/profile.d
 	$(INSTALL_PROGRAM) nix-profile.sh $(DESTDIR)$(sysconfdir)/profile.d/nix.sh
 	$(INSTALL) -d $(DESTDIR)$(libexecdir)/nix
 	$(INSTALL_DATA) readmanifest.pm $(DESTDIR)$(libexecdir)/nix 
 	$(INSTALL_DATA) readconfig.pm $(DESTDIR)$(libexecdir)/nix 
-	$(INSTALL_PROGRAM) download-using-manifests.pl $(DESTDIR)$(libexecdir)/nix 
 	$(INSTALL_PROGRAM) find-runtime-roots.pl $(DESTDIR)$(libexecdir)/nix 
 	$(INSTALL_PROGRAM) generate-patches.pl $(DESTDIR)$(libexecdir)/nix 
+	$(INSTALL_PROGRAM) build-remote.pl $(DESTDIR)$(libexecdir)/nix 
+	$(INSTALL) -d $(DESTDIR)$(libexecdir)/nix/substituters
+	$(INSTALL_PROGRAM) download-using-manifests.pl $(DESTDIR)$(libexecdir)/nix/substituters
+	$(INSTALL_PROGRAM) copy-from-other-stores.pl $(DESTDIR)$(libexecdir)/nix/substituters
 	$(INSTALL) -d $(DESTDIR)$(sysconfdir)/nix
 
 include ../substitute.mk
@@ -29,7 +33,10 @@ EXTRA_DIST = nix-collect-garbage.in \
   readconfig.pm.in \
   nix-build.in \
   download-using-manifests.pl.in \
+  copy-from-other-stores.pl.in \
   generate-patches.pl.in \
-  nix-pack-closure.in nix-unpack-closure.in \
   nix-copy-closure.in \
-  find-runtime-roots.pl.in
+  find-runtime-roots.pl.in \
+  build-remote.pl.in \
+  nix-reduce-build.in \
+  nix-http-export.cgi.in 

scripts/build-remote.pl.in

@@ -0,0 +1,208 @@
+#! @perl@ -w
+
+use strict;
+use Fcntl ':flock';
+use English '-no_match_vars';
+
+# General operation:
+#
+# Try to find a free machine of type $neededSystem.  We do this as
+# follows:
+# - We acquire an exclusive lock on $currentLoad/main-lock.
+# - For each machine $machine of type $neededSystem and for each $slot
+#   less than the maximum load for that machine, we try to get an
+#   exclusive lock on $currentLoad/$machine-$slot (without blocking).
+#   If we get such a lock, we send "accept" to the caller.  Otherwise,
+#   we send "postpone" and exit. 
+# - We release the exclusive lock on $currentLoad/main-lock.
+# - We perform the build on $neededSystem.
+# - We release the exclusive lock on $currentLoad/$machine-$slot.
+#
+# The nice thing about this scheme is that if we die prematurely, the
+# locks are released automatically.
+
+my $loadIncreased = 0;
+
+my $amWilling = shift @ARGV;
+my $localSystem = shift @ARGV;
+my $neededSystem = shift @ARGV;
+my $drvPath = shift @ARGV;
+
+sub sendReply {
+    my $reply = shift;
+    open OUT, ">&3" or die;
+    print OUT "$reply\n";
+    close OUT;
+}
+
+sub decline {
+    sendReply "decline";
+    exit 0;
+}
+
+my $currentLoad = $ENV{"NIX_CURRENT_LOAD"};
+decline unless defined $currentLoad;
+mkdir $currentLoad, 0777 or die unless -d $currentLoad;
+
+my $conf = $ENV{"NIX_REMOTE_SYSTEMS"};
+decline if !defined $conf || ! -e $conf;
+
+# Decline if the local system can do the build.
+decline if $amWilling && ($localSystem eq $neededSystem);
+
+
+# Otherwise find a willing remote machine.
+my %machines;
+my %systemTypes;
+my %sshKeys;
+my %maxJobs;
+my %curJobs;
+
+
+# Read the list of machines.
+open CONF, "< $conf" or die;
+
+while (<CONF>) {
+    chomp;
+    s/\#.*$//g;
+    next if /^\s*$/;
+    /^\s*(\S+)\s+(\S+)\s+(\S+)\s+(\d+)\s*$/ or die;
+    $machines{$1} = "";
+    $systemTypes{$1} = $2;
+    $sshKeys{$1} = $3;
+    $maxJobs{$1} = $4;
+}
+
+close CONF;
+
+
+# Acquire the exclusive lock on $currentLoad/main-lock.
+my $mainLock = "$currentLoad/main-lock";
+open MAINLOCK, ">>$mainLock" or die;
+flock(MAINLOCK, LOCK_EX) or die;
+
+
+# Find a suitable system.
+my $rightType = 0;
+my $machine;
+LOOP: foreach my $cur (keys %machines) {
+    if ($neededSystem eq $systemTypes{$cur}) {
+        $rightType = 1;
+
+        # We have a machine of the right type.  Try to get a lock on
+        # one of the machine's lock files.
+        my $slot = 0;
+        while ($slot < $maxJobs{$cur}) {
+            my $slotLock = "$currentLoad/$cur-$slot";
+            open SLOTLOCK, ">>$slotLock" or die;
+            if (flock(SLOTLOCK, LOCK_EX | LOCK_NB)) {
+                $machine = $cur;
+                last LOOP;
+            }                
+            close SLOTLOCK;
+            $slot++;
+        }
+    }
+}
+
+close MAINLOCK;
+
+
+# Didn't find one?
+if (!defined $machine) {
+    if ($rightType) {
+        sendReply "postpone";
+        exit 0;
+    } else {
+        decline;
+    }
+}
+
+# Yes we did, accept.
+sendReply "accept";
+open IN, "<&4" or die;
+my $x = <IN>;
+chomp $x;
+#print "got $x\n";  
+close IN;
+
+if ($x ne "okay") {
+    exit 0;
+}
+
+
+# Do the actual job.
+print "BUILDING REMOTE: $drvPath on $machine\n";
+
+# Make sure that we don't get any SSH passphrase or host key popups -
+# if there is any problem it should fail, not do something
+# interactive.
+$ENV{"DISPLAY"} = "";
+$ENV{"SSH_PASSWORD_FILE="} = "";
+$ENV{"SSH_ASKPASS="} = "";
+
+my $sshOpts = "-i $sshKeys{$machine} -x";
+
+# Hack to support Cygwin: if we login without a password, we don't
+# have exactly the same right as when we do.  This causes the
+# Microsoft C compiler to fail with certain flags:
+#
+#   http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=99676
+#
+# So as a workaround, we pass a verbatim password.  ssh tries to makes
+# this very hard; the trick is to make it call SSH_ASKPASS to get the
+# password.  (It only calls this command when there is no controlling
+# terminal, but Nix ensures that is is the case.  When doing this
+# manually, use setsid(1).)
+if ($sshKeys{$machine} =~ /^password:/) {
+    my $passwordFile = $sshKeys{$machine};
+    $passwordFile =~ s/^password://;
+    $sshOpts = "ssh -x";
+    $ENV{"SSH_PASSWORD_FILE"} = $passwordFile;
+    $ENV{"SSH_ASKPASS"} = "/tmp/writepass";
+
+    open WRITEPASS, ">/tmp/writepass" or die;
+    print WRITEPASS "#! /bin/sh\ncat \"\$SSH_PASSWORD_FILE\"";
+    close WRITEPASS;
+    chmod 0755, "/tmp/writepass" or die;
+}
+
+my $inputs = `cat inputs`; die if ($? != 0);
+$inputs =~ s/\n/ /g;
+
+my $outputs = `cat outputs`; die if ($? != 0);
+$outputs =~ s/\n/ /g;
+
+print "COPYING INPUTS...\n";
+
+my $maybeSign = "";
+$maybeSign = "--sign" if -e "/nix/etc/nix/signing-key.sec";
+
+system("NIX_SSHOPTS=\"$sshOpts\" nix-copy-closure $machine $maybeSign $drvPath $inputs") == 0
+    or die "cannot copy inputs to $machine: $?";
+
+print "BUILDING...\n";
+
+system("ssh $sshOpts $machine 'nix-store -rvvK $drvPath'") == 0
+    or die "remote build on $machine failed: $?";
+
+print "REMOTE BUILD DONE: $drvPath on $machine\n";
+
+foreach my $output (split '\n', $outputs) {
+    my $maybeSignRemote = "";
+    $maybeSignRemote = "--sign" if $UID != 0;
+    
+    system("ssh $sshOpts $machine 'nix-store --export $maybeSignRemote $output' > dump") == 0
+	or die "cannot copy $output from $machine: $?";
+
+    # This doesn't work yet, since the caller has a lock on the output
+    # path.  We should move towards lock-free invocation of build
+    # hooks and substitutes.
+    #system("nix-store --import < dump") == 0
+    #    or die "cannot import $output: $?";
+
+    # Hack: skip the first 8 bytes (the nix-store --export next
+    # archive marker).  The archive follows.
+    system("(dd bs=1 count=8 of=/dev/null && cat) < dump | nix-store --restore $output") == 0
+	or die "cannot restore $output: $?";
+}

scripts/copy-from-other-stores.pl.in

@@ -0,0 +1,98 @@
+#! @perl@ -w
+
+use strict;
+use File::Basename;
+use IO::Handle;
+
+my $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";
+
+
+STDOUT->autoflush(1);
+
+my @remoteStoresAll = split ':', ($ENV{"NIX_OTHER_STORES"} or "");
+
+my @remoteStores;
+foreach my $dir (@remoteStoresAll) {
+    push @remoteStores, glob($dir);
+}
+
+
+sub findStorePath {
+    my $storePath = shift;
+    
+    my $storePathName = basename $storePath;
+    
+    foreach my $store (@remoteStores) {
+        # Determine whether $storePath exists by looking for the
+        # existence of the info file, and if so, get store path info
+        # from that file.  This rather breaks abstraction: we should
+        # be using `nix-store' for that.  But right now there is no
+        # good way to tell nix-store to access a store mounted under a
+        # different location (there's $NIX_STORE, but that only works
+        # if the remote store is mounted under its "real" location).
+        my $infoFile = "$store/var/nix/db/info/$storePathName";
+        my $storePath2 = "$store/store/$storePathName";
+        if (-f $infoFile && -e $storePath2) {
+            return ($infoFile, $storePath2);
+        }
+    }
+}
+
+
+if ($ARGV[0] eq "--query") {
+
+    while (<STDIN>) {
+        my $cmd = $_; chomp $cmd;
+
+        if ($cmd eq "have") {
+            my $storePath = <STDIN>; chomp $storePath;
+            (my $infoFile) = findStorePath $storePath;
+            print STDOUT ($infoFile ? "1\n" : "0\n");
+        }
+
+        elsif ($cmd eq "info") {
+            my $storePath = <STDIN>; chomp $storePath;
+            (my $infoFile) = findStorePath $storePath;
+            if (!$infoFile) {
+                print "0\n";
+                next; # not an error
+            }
+            print "1\n";
+
+            my $deriver = "";
+            my @references = ();
+
+            open INFO, "<$infoFile" or die "cannot read info file $infoFile\n";
+            while (<INFO>) {
+                chomp;
+                /^([\w-]+): (.*)$/ or die "bad info file";
+                my $key = $1;
+                my $value = $2;
+                if ($key eq "Deriver") { $deriver = $value; }
+                elsif ($key eq "References") { @references = split ' ', $value; }
+            }
+            close INFO;
+
+            print "$deriver\n";
+            print scalar @references, "\n";
+            print "$_\n" foreach @references;
+            print "0\n"; # !!! showing size not supported (yet)
+        }
+
+        else { die "unknown command `$cmd'"; }
+    }
+}
+
+
+elsif ($ARGV[0] eq "--substitute") {
+    die unless scalar @ARGV == 2;
+    my $storePath = $ARGV[1];
+    (my $infoFile, my $sourcePath) = findStorePath $storePath;
+    die unless $infoFile;
+    print "\n*** Copying `$storePath' from `$sourcePath'\n\n";
+    system("$binDir/nix-store --dump $sourcePath | $binDir/nix-store --restore $storePath") == 0
+        or die "cannot copy `$sourcePath' to `$storePath'";
+}
+
+
+else { die; }

scripts/download-using-manifests.pl.in

@@ -5,22 +5,13 @@ use readmanifest;
 use POSIX qw(strftime);
 use File::Temp qw(tempdir);
 
+my $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";
+
+STDOUT->autoflush(1);
+
 my $manifestDir = "@localstatedir@/nix/manifests";
 my $logFile = "@localstatedir@/log/nix/downloads";
 
-open LOGFILE, ">>$logFile" or die "cannot open log file $logFile";
-
-# Create a temporary directory.
-my $tmpDir = tempdir("nix-download.XXXXXX", CLEANUP => 1, TMPDIR => 1)
-    or die "cannot create a temporary directory";
-
-chdir $tmpDir or die "cannot change to `$tmpDir': $!";
-
-my $tmpNar = "$tmpDir/nar";
-my $tmpNar2 = "$tmpDir/nar2";
-
-END { unlink $tmpNar; unlink $tmpNar2; rmdir $tmpDir; }
-
 
 # Load all manifests.
 my %narFiles;
@@ -28,7 +19,6 @@ my %localPaths;
 my %patches;
 
 for my $manifest (glob "$manifestDir/*.nixmanifest") {
-#    print STDERR "reading $manifest\n";
     if (readManifest($manifest, \%narFiles, \%localPaths, \%patches) < 3) {
         print STDERR "you have an old-style manifest `$manifest'; please delete it\n";
         exit 1;
@@ -38,34 +28,42 @@ for my $manifest (glob "$manifestDir/*.nixmanifest") {
 
 # Parse the arguments.
 
-if ($ARGV[0] eq "--query-paths") {
-    foreach my $storePath (keys %narFiles) { print "$storePath\n"; }
-    foreach my $storePath (keys %localPaths) { print "$storePath\n"; }
-    exit 0;
-}
+if ($ARGV[0] eq "--query") {
 
-elsif ($ARGV[0] eq "--query-info") {
-    shift @ARGV;
-    foreach my $storePath (@ARGV) {
-        my $info;
-        if (defined $narFiles{$storePath}) {
-            $info = @{$narFiles{$storePath}}[0];
+    while (<STDIN>) {
+        my $cmd = $_; chomp $cmd;
+
+        if ($cmd eq "have") {
+            my $storePath = <STDIN>; chomp $storePath;
+            print STDOUT ((defined $narFiles{$storePath} or defined $localPaths{$storePath})
+                ? "1\n" : "0\n");
         }
-        elsif (defined $localPaths{$storePath}) {
-            $info = @{$localPaths{$storePath}}[0];
-        }
-        else {
-            next; # not an error
-        }
-        print "$storePath\n";
-        print "$info->{deriver}\n";
-        my @references = split " ", $info->{references};
-        my $count = scalar @references;
-        print "$count\n";
-        foreach my $reference (@references) {
-            print "$reference\n";
+
+        elsif ($cmd eq "info") {
+            my $storePath = <STDIN>; chomp $storePath;
+            my $info;
+            if (defined $narFiles{$storePath}) {
+                $info = @{$narFiles{$storePath}}[0];
+            }
+            elsif (defined $localPaths{$storePath}) {
+                $info = @{$localPaths{$storePath}}[0];
+            }
+            else {
+                print "0\n";
+                next; # not an error
+            }
+            print "1\n";
+            print "$info->{deriver}\n";
+            my @references = split " ", $info->{references};
+            print scalar @references, "\n";
+            print "$_\n" foreach @references;
+            my $size = $info->{size} || 0;
+            print "$size\n";
         }
+        
+        else { die "unknown command `$cmd'"; }
     }
+
     exit 0;
 }
 
@@ -78,6 +76,18 @@ die unless scalar @ARGV == 2;
 my $targetPath = $ARGV[1];
 
 
+# Create a temporary directory.
+my $tmpDir = tempdir("nix-download.XXXXXX", CLEANUP => 1, TMPDIR => 1)
+    or die "cannot create a temporary directory";
+
+chdir $tmpDir or die "cannot change to `$tmpDir': $!";
+
+my $tmpNar = "$tmpDir/nar";
+my $tmpNar2 = "$tmpDir/nar2";
+
+
+open LOGFILE, ">>$logFile" or die "cannot open log file $logFile";
+
 my $date = strftime ("%F %H:%M:%S UTC", gmtime (time));
 print LOGFILE "$$ get $targetPath $date\n";
 
@@ -90,7 +100,7 @@ foreach my $localPath (@{$localPathList}) {
     my $sourcePath = $localPath->{copyFrom};
     if (-e $sourcePath) {
         print "\n*** Step 1/1: copying from $sourcePath\n";
-        system("@bindir@/nix-store --dump $sourcePath | @bindir@/nix-store --restore $targetPath") == 0
+        system("$binDir/nix-store --dump $sourcePath | $binDir/nix-store --restore $targetPath") == 0
             or die "cannot copy `$sourcePath' to `$targetPath'";
         exit 0;
     }
@@ -139,7 +149,7 @@ addToQueue $targetPath;
 
 sub isValidPath {
     my $p = shift;
-    return system("@bindir@/nix-store --check-validity '$p' 2> /dev/null") == 0;
+    return system("$binDir/nix-store --check-validity '$p' 2> /dev/null") == 0;
 }
 
 sub parseHash {
@@ -173,7 +183,7 @@ while ($queueFront < scalar @queue) {
                 my ($baseHashAlgo, $baseHash) = parseHash $patch->{baseHash};
                 my $format = "--base32";
                 $format = "" if $baseHashAlgo eq "md5";
-                my $hash = `@bindir@/nix-hash --type '$baseHashAlgo' $format "$patch->{basePath}"`;
+                my $hash = `$binDir/nix-hash --type '$baseHashAlgo' $format "$patch->{basePath}"`;
                 chomp $hash;
 #                print "  MY HASH is $hash\n";
                 if ($hash ne $baseHash) {
@@ -255,7 +265,7 @@ sub downloadFile {
     $ENV{"PRINT_PATH"} = 1;
     $ENV{"QUIET"} = 1;
     $ENV{"NIX_HASH_ALGO"} = $hashAlgo;
-    my ($hash2, $path) = `@bindir@/nix-prefetch-url '$url' '$hash'`;
+    my ($hash2, $path) = `$binDir/nix-prefetch-url '$url' '$hash'`;
     die "download of `$url' failed" unless $? == 0;
     chomp $hash2;
     chomp $path;
@@ -279,7 +289,7 @@ while (scalar @path > 0) {
             # as a base to one or more patches.  So turn the base path
             # into a NAR archive, to which we can apply the patch.
             print "  packing base path...\n";
-            system("@bindir@/nix-store --dump $v > $tmpNar") == 0
+            system("$binDir/nix-store --dump $v > $tmpNar") == 0
                 or die "cannot dump `$v'";
         }
     }
@@ -307,7 +317,7 @@ while (scalar @path > 0) {
             # This was the last patch.  Unpack the final NAR archive
             # into the target path.
             print "  unpacking patched archive...\n";
-            system("@bindir@/nix-store --restore $v < $tmpNar2") == 0
+            system("$binDir/nix-store --restore $v < $tmpNar2") == 0
                 or die "cannot unpack $tmpNar2 into `$v'";
         }
     }
@@ -329,7 +339,7 @@ while (scalar @path > 0) {
         } else {
             # Unpack the archive into the target path.
             print "  unpacking archive...\n";
-            system("@bunzip2@ < '$narFilePath' | @bindir@/nix-store --restore '$v'") == 0
+            system("@bunzip2@ < '$narFilePath' | $binDir/nix-store --restore '$v'") == 0
                 or die "cannot unpack `$narFilePath' into `$v'";
         }
     }

scripts/nix-build.in

@@ -2,6 +2,8 @@
 
 use strict;
 
+my $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";
+
 
 my $addDrvLink = 0;
 my $addOutLink = 1;
@@ -9,6 +11,8 @@ my $addOutLink = 1;
 my $outLink;
 my $drvLink;
 
+my $dryRun = 0;
+
 my @instArgs = ();
 my @buildArgs = ();
 my @exprs = ();
@@ -77,9 +81,9 @@ EOF
         push @instArgs, ("--attr", $ARGV[$n]);
     }
 
-    elsif ($arg eq "--arg") {
-        die "$0: `--arg' requires two arguments\n" unless $n + 2 < scalar @ARGV;
-        push @instArgs, ("--arg", $ARGV[$n + 1], $ARGV[$n + 2]);
+    elsif ($arg eq "--arg" || $arg eq "--argstr") {
+        die "$0: `$arg' requires two arguments\n" unless $n + 2 < scalar @ARGV;
+        push @instArgs, ($arg, $ARGV[$n + 1], $ARGV[$n + 2]);
         $n += 2;
     }
 
@@ -89,6 +93,11 @@ EOF
         push @buildArgs, ($arg, $ARGV[$n]);
     }
 
+    elsif ($arg eq "--dry-run") {
+        push @buildArgs, "--dry-run";
+        $dryRun = 1;
+    }
+    
     elsif (substr($arg, 0, 1) eq "-") {
         push @buildArgs, $arg;
     }
@@ -117,7 +126,7 @@ foreach my $expr (@exprs) {
     # Instantiate.
     my @drvPaths;
     # !!! would prefer the perl 5.8.0 pipe open feature here.
-    my $pid = open(DRVPATHS, "-|") || exec "@bindir@/nix-instantiate", "--add-root", $drvLink, "--indirect", @instArgs, $expr;
+    my $pid = open(DRVPATHS, "-|") || exec "$binDir/nix-instantiate", "--add-root", $drvLink, "--indirect", @instArgs, $expr;
     while (<DRVPATHS>) {chomp; push @drvPaths, $_;}
     close DRVPATHS or exit 1;
 
@@ -128,11 +137,13 @@ foreach my $expr (@exprs) {
 
     # Build.
     my @outPaths;
-    $pid = open(OUTPATHS, "-|") || exec "@bindir@/nix-store", "--add-root", $outLink, "--indirect", "-rv",
+    $pid = open(OUTPATHS, "-|") || exec "$binDir/nix-store", "--add-root", $outLink, "--indirect", "-rv",
         @buildArgs, @drvPaths;
     while (<OUTPATHS>) {chomp; push @outPaths, $_;}
     close OUTPATHS or exit 1;
 
+    next if $dryRun;
+
     foreach my $outPath (@outPaths) {
         my $target = readlink $outPath or die "cannot read symlink `$outPath'";
         print "$target\n";

scripts/nix-collect-garbage.in

@@ -4,6 +4,8 @@ use strict;
 
 my $profilesDir = "@localstatedir@/nix/profiles";
 
+my $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";
+
 
 # Process the command line arguments.
 my @args = ();
@@ -34,7 +36,7 @@ sub removeOldGenerations {
         $name = $dir . "/" . $name;
         if (-l $name && (readlink($name) =~ /link/)) {
             print STDERR "removing old generations of profile $name\n";
-            system("@bindir@/nix-env", "-p", $name, "--delete-generations", "old");
+            system("$binDir/nix-env", "-p", $name, "--delete-generations", "old");
         }
         elsif (! -l $name && -d $name) {
             removeOldGenerations $name;
@@ -48,4 +50,4 @@ removeOldGenerations $profilesDir if $removeOld;
 
 
 # Run the actual garbage collector.
-exec "@bindir@/nix-store", "--gc", @args;
+exec "$binDir/nix-store", "--gc", @args;

scripts/nix-copy-closure.in

@@ -1,12 +1,11 @@
 #! @perl@ -w
 
-my $binDir = $ENV{"NIX_BIN_DIR"};
-$binDir = "@bindir@" unless defined $binDir;
+my $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";
 
 
 if (scalar @ARGV < 1) {
     print STDERR <<EOF
-Usage: nix-copy-closure [--from | --to] HOSTNAME [--sign] PATHS...
+Usage: nix-copy-closure [--from | --to] HOSTNAME [--sign] [--gzip] PATHS...
 EOF
     ;
     exit 1;

scripts/nix-http-export.cgi.in

@@ -0,0 +1,50 @@
+#! /bin/sh
+
+export HOME=/tmp
+export NIX_REMOTE=daemon
+
+TMP_DIR="${TMP_DIR:-/tmp/nix-export}"
+
+@coreutils@/mkdir -p "$TMP_DIR" || true
+@coreutils@/chmod a+r "$TMP_DIR"
+
+needed_path="?$QUERY_STRING"
+needed_path="${needed_path#*[?&]needed_path=}"
+needed_path="${needed_path%%&*}"
+#needed_path="$(echo $needed_path  | ./unhttp)"
+needed_path="$(echo $needed_path  | sed -e 's/%2B/+/g; s/%3D/=/g')"
+
+echo needed_path: "$needed_path" >&2
+
+NIX_STORE="${NIX_STORE_DIR:-/nix/store}"
+
+echo NIX_STORE: "${NIX_STORE}" >&2
+
+full_path="${NIX_STORE}"/"$needed_path"
+
+if [ "$needed_path" != "${needed_path%.drv}" ]; then
+	echo "Status: 403 You should create the derivation file yourself"
+	echo "Content-Type: text/plain"
+	echo
+	echo "Refusing to disclose derivation contents"
+	exit
+fi
+
+if @bindir@/nix-store --check-validity "$full_path"; then
+	if ! [ -e nix-export/"$needed_path".nar.gz ]; then
+		@bindir@/nix-store --export "$full_path" | @gzip@ > "$TMP_DIR"/"$needed_path".nar.gz
+		@coreutils@/ln -fs  "$TMP_DIR"/"$needed_path".nar.gz nix-export/"$needed_path".nar.gz 
+	fi;
+	echo "Status: 301 Moved"
+	echo "Location: nix-export/"$needed_path".nar.gz"
+	echo
+else 
+	echo "Status: 404 No such path found"
+	echo "Content-Type: text/plain"
+	echo
+	echo "Path not found:"
+	echo "$needed_path"
+	echo "checked:"
+	echo "$full_path"
+fi
+

scripts/nix-install-package.in

@@ -3,6 +3,8 @@
 use strict;
 use File::Temp qw(tempdir);
 
+my $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";
+
 
 sub usageError {
     print STDERR <<EOF;
@@ -59,7 +61,7 @@ if ($interactive && !defined $ENV{"NIX_HAVE_TERMINAL"}) {
     $ENV{"NIX_HAVE_TERMINAL"} = "1";
     $ENV{"LD_LIBRARY_PATH"} = "";
     foreach my $term ("xterm", "konsole", "gnome-terminal", "xterm") {
-        exec($term, "-e", "@bindir@/nix-install-package", @ARGV);
+        exec($term, "-e", "$binDir/nix-install-package", @ARGV);
     }
     die "cannot execute `xterm'";
 }
@@ -122,12 +124,12 @@ if ($interactive) {
 
 
 print "\nPulling manifests...\n";
-system("@bindir@/nix-pull", $manifestURL) == 0
+system("$binDir/nix-pull", $manifestURL) == 0
     or barf "nix-pull failed: $?";
 
 
 print "\nInstalling package...\n";
-system("@bindir@/nix-env", "--install", $outPath, "--force-name", $drvName, @extraNixEnvArgs) == 0
+system("$binDir/nix-env", "--install", $outPath, "--force-name", $drvName, @extraNixEnvArgs) == 0
     or barf "nix-env failed: $?";
 
 

scripts/nix-pack-closure.in

@@ -1,75 +0,0 @@
-#! @perl@ -w
-
-# This tool computes the closure of a path (using "nix-store --query
-# --requisites") and puts the contents of each path in the closure in
-# a big NAR archive that can be installed on another Nix installation
-# using "nix-unpack-closure".
-
-# TODO: make this program "streamy", i.e., don't use a temporary
-# directory.
-
-use strict;
-use File::Temp qw(tempdir);
-
-my $binDir = $ENV{"NIX_BIN_DIR"};
-$binDir = "@bindir@" unless defined $binDir;
-
-my $tmpDir = tempdir("nix-pack-closure.XXXXXX", CLEANUP => 1, TMPDIR => 1)
-    or die "cannot create a temporary directory";
-
-mkdir "$tmpDir/contents", 0755 or die;
-mkdir "$tmpDir/references", 0755 or die;
-mkdir "$tmpDir/derivers", 0755 or die;
-
-open TOPLEVEL, ">$tmpDir/top-level" or die;
-
-
-my %storePaths;
-
-
-while (@ARGV) {
-    my $storePath = shift @ARGV;
-
-    # $storePath might be a symlink to the store, so resolve it.
-    $storePath = (`$binDir/nix-store --query --resolve '$storePath'`
-        or die "cannot resolve `$storePath'");
-    chomp $storePath;
-    print TOPLEVEL $storePath, "\n";
-
-    # Get the closure of this path.
-    my $pid = open(READ,
-        "$binDir/nix-store --query --requisites '$storePath'|") or die;
-    
-    while (<READ>) {
-        chomp;
-        die "bad: $_" unless /^\//;
-        $storePaths{$_} = "";
-    }
-
-    close READ or die "nix-store failed: $?";
-}
-
-
-close TOPLEVEL or die;
-
-
-foreach my $storePath (sort(keys %storePaths)) {
-    print STDERR "packing `$storePath'...\n";
-
-    $storePath =~ /\/([^\/]+)$/;
-    my $name = $1;
-
-    system("$binDir/nix-store --dump '$storePath' > $tmpDir/contents/$name") == 0
-        or die "nix-store --dump failed on `$storePath': $?";
-
-    system("$binDir/nix-store --query --references '$storePath' > $tmpDir/references/$name") == 0
-        or die "nix-store --query --references failed on `$storePath': $?";
-
-    system("$binDir/nix-store --query --deriver '$storePath' > $tmpDir/derivers/$name") == 0
-        or die "nix-store --query --deriver failed on `$storePath': $?";
-}
-
-
-# Write a NAR archive of everything to standard output.
-system("nix-store --dump '$tmpDir'") == 0
-    or die "nix-store --dump failed";

scripts/nix-prefetch-url.in

@@ -36,19 +36,62 @@ if test -n "$expHash"; then
 fi
 
 
+mkTempDir() {
+    if test -n "$tmpPath"; then return; fi
+    local i=0
+    while true; do
+        if test -z "$TMPDIR"; then TMPDIR=/tmp; fi
+        tmpPath=$TMPDIR/nix-prefetch-url-$$-$i
+        if mkdir "$tmpPath"; then break; fi
+        # !!! to bad we can't check for ENOENT in mkdir, so this check
+        # is slightly racy (it bombs out if somebody just removed
+        # $tmpPath...).
+        if ! test -e "$tmpPath"; then exit 1; fi
+        i=$((i + 1))
+    done
+    trap removeTempDir EXIT SIGINT SIGQUIT
+}
+
+removeTempDir() {
+    if test -n "$tmpPath"; then
+        rm -rf "$tmpPath" || true
+    fi
+}
+
+
 doDownload() {
     @curl@ $cacheFlags --fail -# --location --max-redirs 20 --disable-epsv \
         --cookie-jar $tmpPath/cookies "$url" -o $tmpFile
 }
 
 
+# Hack to support the mirror:// scheme from Nixpkgs.
+if test "${url:0:9}" = "mirror://"; then
+    if test -z "$NIXPKGS_ALL"; then
+        echo "Resolving mirror:// URLs requires Nixpkgs.  Please point \$NIXPKGS_ALL at a Nixpkgs tree." >&2
+        exit 1
+    fi
+
+    mkTempDir
+    nix-build "$NIXPKGS_ALL" -A resolveMirrorURLs --argstr url "$url" -o $tmpPath/urls > /dev/null
+
+    expanded=($(cat $tmpPath/urls))
+    if test "${#expanded[*]}" = 0; then
+        echo "$0: cannot resolve $url." >&2
+        exit 1
+    fi
+
+    echo "$url expands to ${expanded[*]} (using ${expanded[0]})" >&2
+    url="${expanded[0]}"
+fi
+
+
 # If we don't know the hash or a file with that hash doesn't exist,
 # download the file and add it to the store.
 if test -z "$finalPath"; then
 
-    tmpPath=/tmp/nix-prefetch-url-$$ # !!! security?
+    mkTempDir
     tmpFile=$tmpPath/$name
-    mkdir $tmpPath # !!! retry if tmpPath already exists
 
     # Optionally do timestamp-based caching of the download.
     # Actually, the only thing that we cache in $NIX_DOWNLOAD_CACHE is
@@ -57,7 +100,7 @@ if test -z "$finalPath"; then
     # garbage-collected independently.
     if test -n "$NIX_DOWNLOAD_CACHE"; then
         echo -n "$url" > $tmpPath/url
-        urlHash=$(nix-hash --type sha256 --base32 --flat $tmpPath/url)
+        urlHash=$(@bindir@/nix-hash --type sha256 --base32 --flat $tmpPath/url)
         echo "$url" > "$NIX_DOWNLOAD_CACHE/$urlHash.url"
         cachedHashFN="$NIX_DOWNLOAD_CACHE/$urlHash.$hashType"
         cachedTimestampFN="$NIX_DOWNLOAD_CACHE/$urlHash.stamp"
@@ -98,8 +141,6 @@ if test -z "$finalPath"; then
         # Add the downloaded file to the Nix store.
         finalPath=$(@bindir@/nix-store --add-fixed "$hashType" $tmpFile)
 
-        if test -n "$tmpPath"; then rm -rf $tmpPath || true; fi
-
         if test -n "$expHash" -a "$expHash" != "$hash"; then
             echo "hash mismatch for URL \`$url'" >&2
             exit 1

scripts/nix-profile.sh.in

@@ -7,5 +7,12 @@ if test -n "$HOME"; then
         @coreutils@/ln -s "$_NIX_DEF_LINK" "$NIX_LINK"
     fi
 
-    export PATH=$NIX_LINK/bin:@prefix@/bin:$PATH
+    export PATH=$NIX_LINK/bin:$PATH
+fi
+
+# This is a quick hack to make fontconfig-based packages in Nixpkgs
+# work out of the box on non-NixOS systems.  Of course, we should
+# really fix fontconfig...
+if test -z "$FONTCONFIG_FILE" -a -e /etc/fonts/fonts.conf; then
+    export FONTCONFIG_FILE=/etc/fonts/fonts.conf
 fi

scripts/nix-pull.in

@@ -7,8 +7,7 @@ use readmanifest;
 my $tmpDir = tempdir("nix-pull.XXXXXX", CLEANUP => 1, TMPDIR => 1)
     or die "cannot create a temporary directory";
 
-my $binDir = $ENV{"NIX_BIN_DIR"};
-$binDir = "@bindir@" unless defined $binDir;
+my $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";
 
 my $libexecDir = $ENV{"NIX_LIBEXEC_DIR"};
 $libexecDir = "@libexecdir@" unless defined $libexecDir;

scripts/nix-push.in

@@ -16,8 +16,7 @@ my $curl = "@curl@ --fail --silent";
 my $extraCurlFlags = ${ENV{'CURL_FLAGS'}};
 $curl = "$curl $extraCurlFlags" if defined $extraCurlFlags;
 
-my $binDir = $ENV{"NIX_BIN_DIR"};
-$binDir = "@bindir@" unless defined $binDir;
+my $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";
 
 my $dataDir = $ENV{"NIX_DATA_DIR"};
 $dataDir = "@datadir@" unless defined $dataDir;
@@ -107,7 +106,7 @@ foreach my $storePath (@storePaths) {
     # Construct a Nix expression that creates a Nix archive.
     my $nixexpr = 
         "((import $dataDir/nix/corepkgs/nar/nar.nix) " .
-        "{storePath = builtins.toPath \"$storePath\"; system = \"@system@\"; hashAlgo = \"$hashAlgo\";}) ";
+        "{storePath = builtins.storePath \"$storePath\"; system = \"@system@\"; hashAlgo = \"$hashAlgo\";}) ";
     
     print NIX $nixexpr;
 }
@@ -116,9 +115,9 @@ print NIX "]";
 close NIX;
 
 
-# Instantiate store expressions from the Nix expression.
+# Instantiate store derivations from the Nix expression.
 my @storeExprs;
-print STDERR "instantiating store expressions...\n";
+print STDERR "instantiating store derivations...\n";
 my $pid = open(READ, "$binDir/nix-instantiate $nixExpr|")
     or die "cannot run nix-instantiate";
 while (<READ>) {
@@ -146,7 +145,7 @@ while (scalar @tmp > 0) {
     # probably wouldn't make that much sense; pumping lots of data
     # around just to compress them won't gain that much.
     $ENV{"NIX_BUILD_HOOK"} = "";
-    my $pid = open(READ, "$binDir/nix-store --realise @tmp2|")
+    my $pid = open(READ, "$binDir/nix-store --no-build-hook --realise @tmp2|")
         or die "cannot run nix-store";
     while (<READ>) {
         chomp;
@@ -224,13 +223,14 @@ writeManifest $manifest, \%narFiles, \%patches;
 sub copyFile {
     my $src = shift;
     my $dst = shift;
-    system("@coreutils@/cp", $src, "$dst.tmp") == 0 or die "cannot copy file";
-    rename("$dst.tmp", "$dst") or die "cannot rename file";
+    my $tmp = "$dst.tmp.$$";
+    system("@coreutils@/cp", $src, $tmp) == 0 or die "cannot copy file";
+    rename($tmp, $dst) or die "cannot rename file: $!";
 }
 
 
-# Upload the archives.
-print STDERR "uploading archives...\n";
+# Upload/copy the archives.
+print STDERR "uploading/copying archives...\n";
 
 sub archiveExists {
     my $name = shift;
@@ -244,9 +244,12 @@ foreach my $narArchive (@narArchives) {
     my $basename = $1;
 
     if ($localCopy) {
+        # Since nix-push creates $dst atomically, if it exists we
+        # don't have to copy again.
+        my $dst = "$localArchivesDir/$basename";
         if (! -f "$localArchivesDir/$basename") {
             print STDERR "  $narArchive\n";
-            copyFile $narArchive, "$localArchivesDir/$basename";
+            copyFile $narArchive, $dst;
         }
     }
     else {

scripts/nix-reduce-build.in

@@ -0,0 +1,171 @@
+#! @shell@
+
+WORKING_DIRECTORY=$(mktemp -d "${TMPDIR:-/tmp}"/nix-reduce-build-XXXXXX);
+cd "$WORKING_DIRECTORY";
+
+if test -z "$1" || test "a--help" = "a$1" ; then
+	echo 'nix-reduce-build (paths or Nix expressions) -- (package sources)' >&2
+	echo As in: >&2
+	echo nix-reduce-build /etc/nixos/nixos -- ssh://user@somewhere.nowhere.example.org >&2
+	echo nix-reduce-build /etc/nixos/nixos -- \\
+	echo "   " \''http://somewhere.nowhere.example.org/nix/nix-http-export.cgi?needed_path='\' >&2
+	echo "  store path name will be added into the end of the URL" >&2
+	echo nix-reduce-build /etc/nixos/nixos -- file://home/user/nar/ >&2
+	echo "  that should be a directory where gzipped 'nix-store --export' ">&2
+	echo "  files are located (they should have .nar.gz extension)"  >&2
+	echo "        Or all together: " >&2
+	echo -e nix-reduce-build /expr.nix /e2.nix -- \\\\\\\n\
+	"    ssh://a@b.example.com http://n.example.com/get-nar?q= file://nar/" >&2
+	echo "        Also supports best-effort local builds of failing expression set:" >&2
+	echo "nix-reduce-build /e.nix -- nix-daemon:// nix-self://" >&2
+	echo "  nix-daemon:// builds using daemon"
+	echo "  nix-self:// builds directly using nix-store from current installation" >&2
+	echo "  nix-daemon-fixed:// and nix-self-fixed:// do the same, but only for" >&2;
+	echo "derivations with specified output hash (sha256, sha1 or md5)." >&2
+	echo "  nix-daemon-substitute:// and nix-self-substitute:// try to substitute" >&2;
+	echo "maximum amount of paths" >&2;
+	echo "  nix-daemon-build:// and nix-self-build:// try to build (not substitute)" >&2;
+	echo "maximum amount of paths" >&2;
+	echo "        If no package sources are specified, required paths are listed." >&2;
+	exit;
+fi;
+
+while ! test "$1" = "--" || test "$1" = "" ; do 
+	echo "$1" >> initial; >&2
+	shift;
+done
+shift;
+echo Will work on $(cat initial | wc -l) targets. >&2
+
+while read ; do
+	case "$REPLY" in 
+		${NIX_STORE_DIR:-/nix/store}/*)
+			echo "$REPLY" >> paths; >&2
+			;;
+		*)
+			(
+				IFS=: ;
+				nix-instantiate $REPLY >> paths;
+			);
+			;;
+	esac;
+done < initial;
+echo Proceeding $(cat paths | wc -l) paths. >&2
+
+while read; do
+	case "$REPLY" in
+		*.drv)
+			echo "$REPLY" >> derivers; >&2
+			;;
+		*)
+			nix-store --query --deriver "$REPLY" >>derivers;
+			;;
+	esac;
+done < paths;
+echo Found $(cat derivers | wc -l) derivers. >&2
+
+cat derivers | xargs nix-store --query -R > derivers-closure;
+echo Proceeding at most $(cat derivers-closure | wc -l) derivers. >&2
+
+cat derivers-closure | egrep '[.]drv$' | xargs nix-store --query --outputs > wanted-paths;
+cat derivers-closure | egrep -v '[.]drv$' >> wanted-paths;
+echo Prepared $(cat wanted-paths | wc -l) paths to get. >&2
+
+cat wanted-paths | xargs nix-store --check-validity --print-invalid > needed-paths;
+echo We need $(cat needed-paths | wc -l) paths. >&2
+
+egrep '[.]drv$' derivers-closure > critical-derivers;
+
+if test -z "$1" ; then
+	cat needed-paths;	
+fi;
+
+refresh_critical_derivers() {
+    echo "Finding needed derivers..." >&2;
+    cat critical-derivers | while read; do
+        if ! (nix-store --query --outputs "$REPLY" | xargs nix-store --check-validity &> /dev/null;); then
+            echo "$REPLY";
+        fi;
+    done > new-critical-derivers;
+    mv new-critical-derivers critical-derivers;
+    echo The needed paths are realized by $(cat critical-derivers | wc -l) derivers. >&2
+}
+
+build_here() {
+    cat critical-derivers | while read; do 
+        echo "Realising $REPLY using nix-daemon" >&2
+        @bindir@/nix-store -r "${REPLY}"
+    done;
+}
+
+try_to_substitute(){
+    cat needed-paths | while read ; do 
+        echo "Building $REPLY using nix-daemon" >&2
+        @bindir@/nix-store -r "${NIX_STORE_DIR:-/nix/store}/${REPLY##*/}"
+    done;
+}
+
+for i in "$@"; do 
+	sshHost="${i#ssh://}";
+	httpHost="${i#http://}";
+	httpsHost="${i#https://}";
+	filePath="${i#file:/}";
+	if [ "$i" != "$sshHost" ]; then
+		cat needed-paths | while read; do 
+			echo "Getting $REPLY and its closure over ssh" >&2
+			nix-copy-closure --from "$sshHost" --gzip "$REPLY" </dev/null || true; 
+		done;
+	elif [ "$i" != "$httpHost" ] || [ "$i" != "$httpsHost" ]; then
+		cat needed-paths | while read; do
+			echo "Getting $REPLY over http/https" >&2
+			curl ${BAD_CERTIFICATE:+-k} -L "$i${REPLY##*/}" | gunzip | nix-store --import;
+		done;
+	elif [ "$i" != "$filePath" ] ; then
+		cat needed-paths | while read; do 
+			echo "Installing $REPLY from file" >&2
+			gunzip < "$filePath/${REPLY##*/}".nar.gz | nix-store --import;
+		done;
+	elif [ "$i" = "nix-daemon://" ] ; then
+		NIX_REMOTE=daemon try_to_substitute;
+		refresh_critical_derivers;
+		NIX_REMOTE=daemon build_here;
+	elif [ "$i" = "nix-self://" ] ; then
+		NIX_REMOTE= try_to_substitute;
+		refresh_critical_derivers;
+		NIX_REMOTE= build_here;
+	elif [ "$i" = "nix-daemon-fixed://" ] ; then
+		refresh_critical_derivers;
+
+		cat critical-derivers | while read; do 
+			if egrep '"(md5|sha1|sha256)"' "$REPLY" &>/dev/null; then
+				echo "Realising $REPLY using nix-daemon" >&2
+				NIX_REMOTE=daemon @bindir@/nix-store -r "${REPLY}"
+			fi;
+		done;
+	elif [ "$i" = "nix-self-fixed://" ] ; then
+		refresh_critical_derivers;
+
+		cat critical-derivers | while read; do 
+			if egrep '"(md5|sha1|sha256)"' "$REPLY" &>/dev/null; then
+				echo "Realising $REPLY using direct Nix build" >&2
+				NIX_REMOTE= @bindir@/nix-store -r "${REPLY}"
+			fi;
+		done;
+	elif [ "$i" = "nix-daemon-substitute://" ] ; then
+		NIX_REMOTE=daemon try_to_substitute;
+	elif [ "$i" = "nix-self-substitute://" ] ; then
+		NIX_REMOTE= try_to_substitute;
+	elif [ "$i" = "nix-daemon-build://" ] ; then
+		refresh_critical_derivers;
+		NIX_REMOTE=daemon build_here;
+	elif [ "$i" = "nix-self-build://" ] ; then
+		refresh_critical_derivers;
+		NIX_REMOTE= build_here;
+	fi;
+	mv needed-paths wanted-paths;
+	cat wanted-paths | xargs nix-store --check-validity --print-invalid > needed-paths;
+	echo We still need $(cat needed-paths | wc -l) paths. >&2
+done;
+
+cd /
+rm -r "$WORKING_DIRECTORY"

scripts/nix-unpack-closure.in

@@ -1,88 +0,0 @@
-#! @perl@ -w
-
-# This tool unpacks the closures created by "nix-pack-closure" and
-# adds them to the Nix store.
-
-# TODO: make this program "streamy", i.e., don't use a temporary
-# directory.
-
-use strict;
-use File::Temp qw(tempdir);
-
-my $binDir = $ENV{"NIX_BIN_DIR"};
-$binDir = "@bindir@" unless defined $binDir;
-
-my $tmpDir = tempdir("nix-unpack-closure.XXXXXX", CLEANUP => 1, TMPDIR => 1)
-    or die "cannot create a temporary directory";
-
-
-# Unpack the NAR archive on standard input.
-system("nix-store --restore '$tmpDir/unpacked'") == 0
-    or die "nix-store --restore failed";
-
-
-open VALID, ">$tmpDir/validity" or die;
-
-
-# For each path in the closure that is not yet valid, add it to the
-# store.  TODO: use proper locking.  Or even better, let nix-store do
-# this.
-opendir(DIR, "$tmpDir/unpacked/contents") or die "cannot open directory: $!";
-
-foreach my $name (sort(readdir DIR)) {
-    next if $name eq "." or $name eq "..";
-
-    my $storePath = "@storedir@/$name"; # !!!
-
-    # !!! this really isn't a good validity check!
-    system "$binDir/nix-store --check-validity '$storePath' 2> /dev/null";
-    if ($? != 0) {
-        print STDERR "unpacking `$storePath'...\n";
-
-        # !!! race
-        system("@coreutils@/rm -rf '$storePath'") == 0
-            or die "cannot remove `$storePath': $?";
-
-        system("$binDir/nix-store --restore '$storePath' < '$tmpDir/unpacked/contents/$name'") == 0
-            or die "nix-store --dump failed on `$storePath': $?";
-        
-        print VALID "$storePath\n";
-
-        open DRV, "<$tmpDir/unpacked/derivers/$name" or die;
-        my $deriver = <DRV>;
-        chomp $deriver;
-        $deriver = "" if $deriver eq "unknown-deriver";
-        close DRV;
-
-        my @refs;
-        open REFS, "<$tmpDir/unpacked/references/$name" or die;
-        while (<REFS>) {
-            chomp;
-            push @refs, $_;
-        }
-        close REFS;
-
-        print VALID "$deriver\n";
-        
-        print VALID (scalar @refs), "\n";
-        foreach my $ref (@refs) {
-            print VALID "$ref\n";
-        }
-    }
-}
-
-closedir(DIR) or die;
-
-
-# Register the invalid paths as valid.
-system("nix-store --register-validity <'$tmpDir/validity'") == 0
-    or die "nix-store --register-validity failed";
-
-
-# Show the top-level paths so that something useful can be done with
-# them, e.g., passing them to `nix-env -i'.
-if (-e "$tmpDir/unpacked/top-level") {
-    open TOPLEVEL, "<$tmpDir/unpacked/top-level" or die;
-    while (<TOPLEVEL>) { print "$_"; }
-    close TOPLEVEL;
-}

src/bsdiff-4.3/bspatch.c

@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD: src/usr.bin/bsdiff/bspatch/bspatch.c,v 1.1 2005/08/06 01:59:
 #include <errno.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <sys/types.h>
 
 static off_t offtin(u_char *buf)
 {

src/libexpr/Makefile.am

@@ -2,11 +2,13 @@ pkglib_LTLIBRARIES = libexpr.la
 
 libexpr_la_SOURCES = \
  nixexpr.cc eval.cc primops.cc lexer-tab.cc parser-tab.cc \
- get-drvs.cc attr-path.cc expr-to-xml.cc common-opts.cc
+ get-drvs.cc attr-path.cc expr-to-xml.cc common-opts.cc \
+ names.cc
 
 pkginclude_HEADERS = \
  nixexpr.hh eval.hh parser.hh lexer-tab.hh parser-tab.hh \
- get-drvs.hh attr-path.hh expr-to-xml.hh common-opts.hh
+ get-drvs.hh attr-path.hh expr-to-xml.hh common-opts.hh \
+ names.hh
 
 libexpr_la_LIBADD = ../libutil/libutil.la ../libstore/libstore.la \
  ../boost/format/libformat.la

src/libexpr/eval.cc

@@ -1,5 +1,3 @@
-#include <iostream>
-
 #include "eval.hh"
 #include "parser.hh"
 #include "hash.hh"
@@ -15,19 +13,6 @@
 
 
 namespace nix {
-
-
-int cacheTerms;
-
-bool shortCircuit;
-bool closedTerms; // don't substitute under terms known to be closed
-bool substCache; // memoization of the term substitution function
-bool posInfo; // attach position info to functions, assertions, attributes
-
-#define maxActiveCalls 4096
-
-ATerm activeCalls[maxActiveCalls];
-unsigned int activeCallsCount = 0;
     
 
 EvalState::EvalState()
@@ -38,15 +23,6 @@ EvalState::EvalState()
     initNixExprHelpers();
 
     addPrimOps();
-
-    if (!string2Int(getEnv("NIX_TERM_CACHE"), cacheTerms)) cacheTerms = 1;
-    shortCircuit = getEnv("NIX_SHORT_CIRCUIT", "0") == "1";
-    strictMode = getEnv("NIX_STRICT", "0") == "1";
-    closedTerms = getEnv("NIX_CLOSED_TERMS", "1") == "1";
-    substCache = getEnv("NIX_SUBST_CACHE", "1") == "1";
-    posInfo = getEnv("NIX_POS_INFO", "1") == "1";
-
-    ATprotectMemory(activeCalls, maxActiveCalls);
 }
 
 
@@ -72,6 +48,11 @@ LocalNoInlineNoReturn(void throwEvalError(const char * s, const string & s2))
     throw EvalError(format(s) % s2);
 }
 
+LocalNoInlineNoReturn(void throwTypeError(const char * s))
+{
+    throw TypeError(s);
+}
+
 LocalNoInlineNoReturn(void throwTypeError(const char * s, const string & s2))
 {
     throw TypeError(format(s) % s2);
@@ -93,90 +74,91 @@ LocalNoInline(void addErrorPrefix(Error & e, const char * s, const string & s2,
 }
 
 
-Expr speculativeEval(EvalState & state, Expr e)
+/* Pattern-match `pat' against `arg'.  The result is a set of
+   substitutions (`subs') and a set of recursive substitutions
+   (`subsRecursive').  The latter can refer to the variables bound by
+   both `subs' and `subsRecursive'. */
+static void patternMatch(EvalState & state,
+    Pattern pat, Expr arg, ATermMap & subs, ATermMap & subsRecursive)
 {
-    if (!state.strictMode) return e;
-    try {
-        return evalExpr(state, e);
-    } catch (EvalError & err) {
-        /* ignore, pass the original arg and depend on
-           laziness */
-        return e;
+    ATerm name;
+    ATermList formals;
+    Pattern pat1, pat2;
+    ATermBool ellipsis;
+    
+    if (matchVarPat(pat, name)) 
+        subs.set(name, arg);
+
+    else if (matchAttrsPat(pat, formals, ellipsis)) {
+
+        arg = evalExpr(state, arg);
+
+        /* Get the actual arguments. */
+        ATermMap attrs;
+        queryAllAttrs(arg, attrs);
+        unsigned int nrAttrs = attrs.size();
+
+        /* For each formal argument, get the actual argument.  If
+           there is no matching actual argument but the formal
+           argument has a default, use the default. */
+        unsigned int attrsUsed = 0;
+        for (ATermIterator i(formals); i; ++i) {
+            Expr name, def;
+            DefaultValue def2;
+            if (!matchFormal(*i, name, def2)) abort(); /* can't happen */
+
+            Expr value = attrs[name];
+
+            if (value == 0) {
+                if (!matchDefaultValue(def2, def)) def = 0;
+                if (def == 0) throw TypeError(format("the argument named `%1%' required by the function is missing")
+                    % aterm2String(name));
+                subsRecursive.set(name, def);
+            } else {
+                attrsUsed++;
+                attrs.remove(name);
+                subs.set(name, value);
+            }
+
+        }
+
+        /* Check that each actual argument is listed as a formal
+           argument (unless the attribute match specifies a `...'). */
+        if (ellipsis == eFalse && attrsUsed != nrAttrs)
+            throw TypeError(format("the function does not expect an argument named `%1%'")
+                % aterm2String(attrs.begin()->key));
     }
+
+    else if (matchAtPat(pat, pat1, pat2)) {
+        patternMatch(state, pat1, arg, subs, subsRecursive);
+        patternMatch(state, pat2, arg, subs, subsRecursive);
+    }
+
+    else abort();
 }
 
 
 /* Substitute an argument set into the body of a function. */
 static Expr substArgs(EvalState & state,
-    Expr body, ATermList formals, Expr arg)
+    Expr body, Pattern pat, Expr arg)
 {
-    unsigned int nrFormals = ATgetLength(formals);
-    ATermMap subs(nrFormals);
-
-    /* Get the actual arguments and put them in the substitution. */
-    ATermMap args;
-    queryAllAttrs(arg, args);
-    for (ATermMap::const_iterator i = args.begin(); i != args.end(); ++i)
-        subs.set(i->key, speculativeEval(state, i->value));
+    ATermMap subs(16), subsRecursive(16);
     
-    /* Get the formal arguments. */
-    ATermVector defsUsed;
-    ATermList recAttrs = ATempty;
-    for (ATermIterator i(formals); i; ++i) {
-        Expr name, def;
-        ValidValues valids2;
-        DefaultValue def2;
-        if (!matchFormal(*i, name, valids2, def2)) abort(); /* can't happen */
+    patternMatch(state, pat, arg, subs, subsRecursive);
 
-        Expr value = subs[name];
-        
-        if (value == 0) {
-            if (!matchDefaultValue(def2, def)) def = 0;
-            if (def == 0) throw TypeError(format("the argument named `%1%' required by the function is missing")
-                % aterm2String(name));
-            value = def;
-            defsUsed.push_back(name);
-            recAttrs = ATinsert(recAttrs, makeBind(name, def, makeNoPos()));
-        }
-
-        ATermList valids;
-        if (matchValidValues(valids2, valids)) {
-            value = evalExpr(state, value);
-            bool found = false;
-            for (ATermIterator j(valids); j; ++j) {
-                Expr v = evalExpr(state, *j);
-                if (value == v) {
-                    found = true;
-                    break;
-                }
-            }
-            if (!found) throw TypeError(format("the argument named `%1%' has an illegal value")
-                % aterm2String(name));            
-        }
-    }
-
-    /* Make a recursive attribute set out of the (argument-name,
-       value) tuples.  This is so that we can support default
-       parameters that refer to each other, e.g.  ({x, y ? x + x}: y)
-       {x = "foo";} evaluates to "foofoo". */
-    if (defsUsed.size() != 0) {
-        for (ATermMap::const_iterator i = args.begin(); i != args.end(); ++i)
+    /* If we used any default values, make a recursive attribute set
+       out of the (argument-name, value) tuples.  This is so that we
+       can support default values that refer to each other, e.g.  ({x,
+       y ? x + x}: y) {x = "foo";} evaluates to "foofoo". */
+    if (subsRecursive.size() != 0) {
+        ATermList recAttrs = ATempty;
+        foreach (ATermMap::const_iterator, i, subs)
+            recAttrs = ATinsert(recAttrs, makeBind(i->key, i->value, makeNoPos()));
+        foreach (ATermMap::const_iterator, i, subsRecursive)
             recAttrs = ATinsert(recAttrs, makeBind(i->key, i->value, makeNoPos()));
         Expr rec = makeRec(recAttrs, ATempty);
-        for (ATermVector::iterator i = defsUsed.begin(); i != defsUsed.end(); ++i)
-            subs.set(*i, makeSelect(rec, *i));
-    }
-    
-    if (subs.size() != nrFormals) {
-        /* One or more actual arguments were not declared as formal
-           arguments.  Find out which. */
-        for (ATermIterator i(formals); i; ++i) {
-            Expr name; ATerm d1, d2;
-            if (!matchFormal(*i, name, d1, d2)) abort();
-            subs.remove(name);
-        }
-        throw TypeError(format("the function does not expect an argument named `%1%'")
-            % aterm2String(subs.begin()->key));
+        foreach (ATermMap::const_iterator, i, subsRecursive)
+            subs.set(i->key, makeSelect(rec, i->key));
     }
 
     return substitute(Substitution(0, &subs), body);
@@ -188,11 +170,12 @@ static Expr substArgs(EvalState & state,
    to attributes substituted with selection expressions on the
    original set.  E.g., e = `rec {x = f x y; y = x;}' becomes `{x = f
    (e.x) (e.y); y = e.x;}'. */
-LocalNoInline(ATerm expandRec(ATerm e, ATermList rbnds, ATermList nrbnds))
+LocalNoInline(ATerm expandRec(EvalState & state, ATerm e, ATermList rbnds, ATermList nrbnds))
 {
     ATerm name;
     Expr e2;
     Pos pos;
+    Expr eOverrides = 0;
 
     /* Create the substitution list. */
     ATermMap subs(ATgetLength(rbnds) + ATgetLength(nrbnds));
@@ -202,9 +185,26 @@ LocalNoInline(ATerm expandRec(ATerm e, ATermList rbnds, ATermList nrbnds))
     }
     for (ATermIterator i(nrbnds); i; ++i) {
         if (!matchBind(*i, name, e2, pos)) abort(); /* can't happen */
+        if (name == sOverrides) eOverrides = e2;
         subs.set(name, e2);
     }
 
+    /* If the rec contains an attribute called `__overrides', then
+       evaluate it, and add the attributes in that set to the rec.
+       This allows overriding of recursive attributes, which is
+       otherwise not possible.  (You can use the // operator to
+       replace an attribute, but other attributes in the rec will
+       still reference the original value, because that value has been
+       substituted into the bodies of the other attributes.  Hence we
+       need __overrides.) */
+    ATermMap overrides;
+    if (eOverrides) {
+        eOverrides = evalExpr(state, eOverrides);
+        queryAllAttrs(eOverrides, overrides, false);
+        foreach (ATermMap::const_iterator, i, overrides)
+            subs.set(i->key, i->value);
+    }
+
     Substitution subs_(0, &subs);
 
     /* Create the non-recursive set. */
@@ -214,6 +214,10 @@ LocalNoInline(ATerm expandRec(ATerm e, ATermList rbnds, ATermList nrbnds))
         as.set(name, makeAttrRHS(substitute(subs_, e2), pos));
     }
 
+    if (eOverrides)
+        foreach (ATermMap::const_iterator, i, overrides)
+            as.set(i->key, makeAttrRHS(i->value, makeNoPos()));
+
     /* Copy the non-recursive bindings.  !!! inefficient */
     for (ATermIterator i(nrbnds); i; ++i) {
         if (!matchBind(*i, name, e2, pos)) abort(); /* can't happen */
@@ -342,9 +346,11 @@ string coerceToString(EvalState & state, Expr e, PathSet & context,
     }
         
     ATermList es;
-    if (matchAttrs(e, es))
-        return coerceToString(state, makeSelect(e, toATerm("outPath")),
-            context, coerceMore, copyToStore);
+    if (matchAttrs(e, es)) {
+        Expr e2 = queryAttr(e, "outPath");
+        if (!e2) throwTypeError("cannot coerce an attribute set (except a derivation) to a string");
+        return coerceToString(state, e2, context, coerceMore, copyToStore);
+    }
 
     if (coerceMore) {
 
@@ -416,17 +422,20 @@ Path coerceToPath(EvalState & state, Expr e, PathSet & context)
 
 Expr autoCallFunction(Expr e, const ATermMap & args)
 {
-    ATermList formals;
+    Pattern pat;
     ATerm body, pos;
+    ATermList formals;
+    ATermBool ellipsis;
     
-    if (matchFunction(e, formals, body, pos)) {
+    /* !!! this should be more general */
+    if (matchFunction(e, pat, body, pos) && matchAttrsPat(pat, formals, ellipsis)) {
         ATermMap actualArgs(ATgetLength(formals));
         
         for (ATermIterator i(formals); i; ++i) {
-            Expr name, def, value; ATerm values, def2;
-            if (!matchFormal(*i, name, values, def2)) abort();
+            Expr name, def, value; ATerm def2;
+            if (!matchFormal(*i, name, def2)) abort();
             if ((value = args.get(name)))
-                actualArgs.set(name, makeAttrRHS(allocCell(value), makeNoPos()));
+                actualArgs.set(name, makeAttrRHS(value, makeNoPos()));
             else if (!matchDefaultValue(def2, def))
                 throw TypeError(format("cannot auto-call a function that has an argument without a default value (`%1%')")
                     % aterm2String(name));
@@ -464,8 +473,8 @@ LocalNoInline(Expr evalVar(EvalState & state, ATerm name))
 
 LocalNoInline(Expr evalCall(EvalState & state, Expr fun, Expr arg))
 {
-    ATermList formals;
-    ATerm pos, name;
+    Pattern pat;
+    ATerm pos;
     Expr body;
         
     /* Evaluate the left-hand side. */
@@ -491,10 +500,9 @@ LocalNoInline(Expr evalCall(EvalState & state, Expr fun, Expr arg))
             return makePrimOp(arity, funBlob, args);
     }
 
-    else if (matchFunction(fun, formals, body, pos)) {
-        arg = evalExpr(state, arg);
+    else if (matchFunction(fun, pat, body, pos)) {
         try {
-            return evalExpr(state, substArgs(state, allocCells(body), formals, arg));
+            return evalExpr(state, substArgs(state, body, pat, arg));
         } catch (Error & e) {
             addErrorPrefix(e, "while evaluating the function at %1%:\n",
                 showPos(pos));
@@ -502,19 +510,6 @@ LocalNoInline(Expr evalCall(EvalState & state, Expr fun, Expr arg))
         }
     }
         
-    else if (matchFunction1(fun, name, body, pos)) {
-        try {
-            arg = speculativeEval(state, arg);
-            ATermMap subs(1);
-            subs.set(name, allocCell(arg));
-            return evalExpr(state, substitute(Substitution(0, &subs), allocCells(body)));
-        } catch (Error & e) {
-            addErrorPrefix(e, "while evaluating the function at %1%:\n",
-                showPos(pos));
-            throw;
-        }
-    }
-
     else throwTypeError(
         "attempt to call something which is neither a function nor a primop (built-in operation) but %1%",
         showType(fun));
@@ -662,10 +657,6 @@ Expr evalExpr2(EvalState & state, Expr e)
     
     Expr e1, e2, e3;
     ATerm name, pos;
-
-    int bla;
-    if (matchCell(e, bla, e1)) e = e1;
-
     AFun sym = ATgetAFun(e);
 
     /* Normal forms. */
@@ -675,7 +666,6 @@ Expr evalExpr2(EvalState & state, Expr e)
         sym == symInt ||
         sym == symBool ||
         sym == symFunction ||
-        sym == symFunction1 ||
         sym == symAttrs ||
         sym == symList ||
         sym == symPrimOp)
@@ -699,7 +689,7 @@ Expr evalExpr2(EvalState & state, Expr e)
     /* Mutually recursive sets. */
     ATermList rbnds, nrbnds;
     if (matchRec(e, rbnds, nrbnds))
-        return expandRec(e, rbnds, nrbnds);
+        return expandRec(state, e, rbnds, nrbnds);
 
     /* Conditionals. */
     if (matchIf(e, e1, e2, e3))
@@ -757,141 +747,41 @@ Expr evalExpr2(EvalState & state, Expr e)
     if (matchOpConcat(e, e1, e2)) return evalOpConcat(state, e1, e2);
 
     /* Barf. */
-    //printMsg(lvlError, format("%1%") % e);
     abort();
 }
 
 
-class ShortCircuit
-{
-};
-
-
-unsigned int fnord;
-
-
-void maybeShortCircuit(EvalState & state, Expr e, Expr nf)
-{
-    for (unsigned int i = 0; i < activeCallsCount; ++i) {
-        Expr fun, arg;
-        if (!matchCall(activeCalls[i], fun, arg)) abort();
-        if (arg == e) {
-            //printMsg(lvlError, format("blaat"));
-            //printMsg(lvlError, format("blaat %1% %2% %3%") % fun % arg % e);
-            Expr res = state.normalForms.get(makeCall(fun, nf));
-            if (res) {
-                fnord++;
-                //printMsg(lvlError, format("blaat"));
-                throw ShortCircuit();
-            }
-        }
-    }
-}
-
-
 Expr evalExpr(EvalState & state, Expr e)
 {
     checkInterrupt();
 
-#if 1
+#if 0
     startNest(nest, lvlVomit,
         format("evaluating expression: %1%") % e);
 #endif
 
     state.nrEvaluated++;
 
-    if (cacheTerms == 0) return evalExpr2(state, e);
-
-    if (cacheTerms == 2) {
-        int pseudoAddr;
-        Expr e2;
-        if (!matchCell(e, pseudoAddr, e2)) return evalExpr2(state, e);
-    }
-    
     /* Consult the memo table to quickly get the normal form of
        previously evaluated expressions. */
     Expr nf = state.normalForms.get(e);
     if (nf) {
-        //if (nf == makeBlackHole())
-        //    throwEvalError("infinite recursion encountered");
+        if (nf == makeBlackHole())
+            throwEvalError("infinite recursion encountered");
         state.nrCached++;
         return nf;
     }
 
-    Expr fun, arg;
-    if (shortCircuit && matchCall(e, fun, arg)) {
-
-#if 0        
-        Expr arg2 = state.normalForms.get(arg);
-        if (arg2) { /* the evaluated argument is now known */
-            //printMsg(lvlError, "foo");
-            /* do we know the result of the same function called
-               with the evaluated argument? */
-            Expr res = state.normalForms.get(makeCall(fun, arg2));
-            if (res) { /* woohoo! */
-                printMsg(lvlError, "dingdong");
-                state.normalForms.set(e, res);
-                return res;
-            }
-        }
-#endif
-
-        assert(activeCallsCount < maxActiveCalls);
-        activeCalls[activeCallsCount++] = e;
-
-        //state.normalForms.set(e, makeBlackHole());
-        try {
-            nf = evalExpr2(state, e);
-        }
-        catch (ShortCircuit & exception) {
-            //printMsg(lvlError, "catch!");
-            Expr arg2 = state.normalForms.get(arg);
-            if (arg2) { /* the evaluated argument is now known */
-                /* do we know the result of the same function called
-                   with the evaluated argument? */
-                Expr res = state.normalForms.get(makeCall(fun, arg2));
-                if (res) { /* woohoo! */
-                    //printMsg(lvlError, "woohoo!");
-                    //printMsg(lvlError, format("woohoo! %1% %2% %3% %4%") % fun % arg % arg2 % res);
-                    activeCallsCount--;
-                    state.normalForms.set(e, res);
-                    maybeShortCircuit(state, e, res);
-                    return res;
-                }
-            }
-            activeCallsCount--;
-            state.normalForms.remove(e);
-            throw; /* not for us */
-        }
-        catch (...) {
-            activeCallsCount--;
-            state.normalForms.remove(e);
-            throw;
-        }
-        activeCallsCount--;
-        state.normalForms.set(e, nf);
-        Expr arg2 = state.normalForms.get(arg);
-        if (arg2) state.normalForms.set(makeCall(fun, arg2), nf);
-        maybeShortCircuit(state, e, nf);
-        return nf;
-        
-    }
-
-    else {
-        
-        /* Otherwise, evaluate and memoize. */
-        //state.normalForms.set(e, makeBlackHole());
-        try {
-            nf = evalExpr2(state, e);
-        } catch (...) {
-            state.normalForms.remove(e);
-            throw;
-        }
-        state.normalForms.set(e, nf);
-        if (shortCircuit) maybeShortCircuit(state, e, nf);
-        return nf;
-
+    /* Otherwise, evaluate and memoize. */
+    state.normalForms.set(e, makeBlackHole());
+    try {
+        nf = evalExpr2(state, e);
+    } catch (Error & err) {
+        state.normalForms.remove(e);
+        throw;
     }
+    state.normalForms.set(e, nf);
+    return nf;
 }
 
 
@@ -935,29 +825,6 @@ static Expr strictEvalExpr_(EvalState & state, Expr e, ATermMap & nfs)
         return makeList(ATreverse(es2));
     }
     
-    ATermList formals;
-    ATerm body, pos;
-    if (matchFunction(e, formals, body, pos)) {
-        ATermList formals2 = ATempty;
-        
-        for (ATermIterator i(formals); i; ++i) {
-            Expr name; ValidValues valids; ATerm dummy;
-            if (!matchFormal(*i, name, valids, dummy)) abort();
-
-            ATermList valids2;
-            if (matchValidValues(valids, valids2)) {
-                ATermList valids3 = ATempty;
-                for (ATermIterator j(valids2); j; ++j)
-                    valids3 = ATinsert(valids3, strictEvalExpr(state, *j, nfs));
-                valids = makeValidValues(ATreverse(valids3));
-            }
-
-            formals2 = ATinsert(formals2, makeFormal(name, valids, dummy));
-        }
-        
-        return makeFunction(ATreverse(formals2), body, pos);
-    }
-    
     return e;
 }
 
@@ -987,24 +854,16 @@ extern "C" {
     unsigned long AT_calcAllocatedSize();
 }
 
-
-unsigned int substs = 0;
-unsigned int substsCached = 0;
-
-
 void printEvalStats(EvalState & state)
 {
     char x;
     bool showStats = getEnv("NIX_SHOW_STATS", "0") != "0";
-    printMsg(lvlError, format("FNORD %1%") % fnord);
     printMsg(showStats ? lvlInfo : lvlDebug,
-        format("evaluated %1% expressions, %2% cache hits, %3%%% efficiency, used %4% ATerm bytes, used %5% bytes of stack space, %6% substitutions (%7% cached)")
+        format("evaluated %1% expressions, %2% cache hits, %3%%% efficiency, used %4% ATerm bytes, used %5% bytes of stack space")
         % state.nrEvaluated % state.nrCached
         % ((float) state.nrCached / (float) state.nrEvaluated * 100)
         % AT_calcAllocatedSize()
-        % (&x - deepestStack)
-        % substs
-        % substsCached);
+        % (&x - deepestStack));
     if (showStats)
         printATermMapStats();
 }

src/libexpr/eval.hh

@@ -27,9 +27,6 @@ struct EvalState;
 typedef Expr (* PrimOp) (EvalState &, const ATermVector & args);
 
 
-extern int cacheTerms; // 0 = don't, 1 = do, 2 = "cell" terms only
-
-
 struct EvalState 
 {
     ATermMap normalForms;
@@ -41,10 +38,6 @@ struct EvalState
     unsigned int nrEvaluated;
     unsigned int nrCached;
 
-    bool strictMode;
-
-    ATermMap parsings; /* path -> expr mapping */
-
     EvalState();
 
     void addPrimOps();

src/libexpr/expr-to-xml.cc

@@ -4,6 +4,8 @@
 #include "aterm.hh"
 #include "util.hh"
 
+#include <cstdlib>
+
 
 namespace nix {
 
@@ -38,6 +40,31 @@ static void showAttrs(const ATermMap & attrs, XMLWriter & doc,
 }
 
 
+static void printPatternAsXML(Pattern pat, XMLWriter & doc)
+{
+    ATerm name;
+    ATermList formals;
+    Pattern pat1, pat2;
+    ATermBool ellipsis;
+    if (matchVarPat(pat, name))
+        doc.writeEmptyElement("varpat", singletonAttrs("name", aterm2String(name)));
+    else if (matchAttrsPat(pat, formals, ellipsis)) {
+        XMLOpenElement _(doc, "attrspat");
+        for (ATermIterator i(formals); i; ++i) {
+            Expr name; ATerm dummy;
+            if (!matchFormal(*i, name, dummy)) abort();
+            doc.writeEmptyElement("attr", singletonAttrs("name", aterm2String(name)));
+        }
+        if (ellipsis == eTrue) doc.writeEmptyElement("ellipsis");
+    }
+    else if (matchAtPat(pat, pat1, pat2)) {
+        XMLOpenElement _(doc, "at");
+        printPatternAsXML(pat1, doc);
+        printPatternAsXML(pat2, doc);
+    }
+}
+
+
 static void printTermAsXML(Expr e, XMLWriter & doc, PathSet & context,
     ExprSet & drvsSeen)
 {
@@ -45,8 +72,8 @@ static void printTermAsXML(Expr e, XMLWriter & doc, PathSet & context,
     string s;
     ATerm s2;
     int i;
-    ATermList as, es, formals;
-    ATerm body, pos;
+    ATermList as, es;
+    ATerm pat, body, pos;
 
     checkInterrupt();
 
@@ -107,22 +134,9 @@ static void printTermAsXML(Expr e, XMLWriter & doc, PathSet & context,
             printTermAsXML(*i, doc, context, drvsSeen);
     }
 
-    else if (matchFunction(e, formals, body, pos)) {
+    else if (matchFunction(e, pat, body, pos)) {
         XMLOpenElement _(doc, "function");
-        
-        for (ATermIterator i(formals); i; ++i) {
-            Expr name; ValidValues valids; ATerm dummy;
-            if (!matchFormal(*i, name, valids, dummy)) abort();
-            XMLOpenElement _(doc, "arg", singletonAttrs("name", aterm2String(name)));
-
-            ATermList valids2;
-            if (matchValidValues(valids, valids2)) {
-                for (ATermIterator j(valids2); j; ++j) {
-                    XMLOpenElement _(doc, "value");
-                    printTermAsXML(*j, doc, context, drvsSeen);
-                }
-            }
-        }
+        printPatternAsXML(pat, doc);
     }
 
     else

src/libexpr/get-drvs.cc

@@ -102,7 +102,7 @@ static bool getDerivation(EvalState & state, Expr e,
 
         boost::shared_ptr<ATermMap> attrs(new ATermMap());
         queryAllAttrs(e, *attrs, false);
-    
+        
         Expr a = attrs->get(toATerm("type"));
         if (!a || evalStringNoCtx(state, a) != "derivation") return true;
 
@@ -173,24 +173,30 @@ static void getDerivations(EvalState & state, Expr e,
 
         /* !!! undocumented hackery to support combining channels in
            nix-env.cc. */
-        Expr e2 = drvMap.get(toATerm("_combineChannels"));
-        bool combineChannels = e2 && evalBool(state, e2);
-        
-        for (ATermMap::const_iterator i = drvMap.begin(); i != drvMap.end(); ++i) {
-            startNest(nest, lvlDebug,
-                format("evaluating attribute `%1%'") % aterm2String(i->key));
-            string pathPrefix2 = addToPath(pathPrefix, aterm2String(i->key));
-            if (combineChannels) {
-                if (((string) aterm2String(i->key)) != "_combineChannels")
-                    getDerivations(state, i->value, pathPrefix2, autoArgs, drvs, doneExprs);
-            }
-            else if (getDerivation(state, i->value, pathPrefix2, drvs, doneExprs)) {
+        bool combineChannels = drvMap.get(toATerm("_combineChannels"));
+
+        /* Consider the attributes in sorted order to get more
+           deterministic behaviour in nix-env operations (e.g. when
+           there are names clashes between derivations, the derivation
+           bound to the attribute with the "lower" name should take
+           precedence). */
+        typedef std::map<string, Expr> AttrsSorted;
+        AttrsSorted attrsSorted;
+        foreach (ATermMap::const_iterator, i, drvMap)
+            attrsSorted[aterm2String(i->key)] = i->value;
+
+        foreach (AttrsSorted::iterator, i, attrsSorted) {
+            startNest(nest, lvlDebug, format("evaluating attribute `%1%'") % i->first);
+            string pathPrefix2 = addToPath(pathPrefix, i->first);
+            if (combineChannels)
+                getDerivations(state, i->second, pathPrefix2, autoArgs, drvs, doneExprs);
+            else if (getDerivation(state, i->second, pathPrefix2, drvs, doneExprs)) {
                 /* If the value of this attribute is itself an
                    attribute set, should we recurse into it?  => Only
                    if it has a `recurseForDerivations = true'
                    attribute. */
                 ATermList es;
-                Expr e = evalExpr(state, i->value);
+                Expr e = evalExpr(state, i->second), e2;
                 if (matchAttrs(e, es)) {
                     ATermMap attrs(ATgetLength(es));
                     queryAllAttrs(e, attrs, false);

src/libexpr/lexer.l

@@ -4,6 +4,7 @@
 
 
 %x STRING
+%x IND_STRING
 
 
 %{
@@ -94,6 +95,7 @@ let         { return LET; }
 in          { return IN; }
 rec         { return REC; }
 inherit     { return INHERIT; }
+\.\.\.      { return ELLIPSIS; }
 
 \=\=        { return EQ; }
 \!\=        { return NEQ; }
@@ -122,6 +124,30 @@ inherit     { return INHERIT; }
 <STRING>\"  { BEGIN(INITIAL); return '"'; }
 <STRING>.   return yytext[0]; /* just in case: shouldn't be reached */
 
+\'\'(\ *\n)?     { BEGIN(IND_STRING); return IND_STRING_OPEN; }
+<IND_STRING>([^\$\']|\$[^\{\']|\'[^\'\$])+ {
+                   yylval->t = makeIndStr(toATerm(yytext));
+                   return IND_STR;
+                 }
+<IND_STRING>\'\'\$ {
+                   yylval->t = makeIndStr(toATerm("$"));
+                   return IND_STR;
+                 }
+<IND_STRING>\'\'\' {
+                   yylval->t = makeIndStr(toATerm("''"));
+                   return IND_STR;
+                 }
+<IND_STRING>\'\'\\. {
+                   yylval->t = unescapeStr(yytext + 2);
+                   return IND_STR;
+                 }
+<IND_STRING>\$\{ { BEGIN(INITIAL); return DOLLAR_CURLY; }
+<IND_STRING>\'\' { BEGIN(INITIAL); return IND_STRING_CLOSE; }
+<IND_STRING>\'   {
+                   yylval->t = makeIndStr(toATerm("'"));
+                   return IND_STR;
+                 }
+<IND_STRING>.    return yytext[0]; /* just in case: shouldn't be reached */
 
 {PATH}      { yylval->t = toATerm(yytext); return PATH; /* !!! alloc */ }
 {URI}       { yylval->t = toATerm(yytext); return URI; /* !!! alloc */ }
@@ -148,4 +174,10 @@ void backToString(yyscan_t scanner)
     BEGIN(STRING);
 }
 
+void backToIndString(yyscan_t scanner)
+{
+    struct yyguts_t * yyg = (struct yyguts_t *) scanner;
+    BEGIN(IND_STRING);
+}
+
 }

src/libexpr/names.cc

@@ -92,25 +92,6 @@ int compareVersions(const string & v1, const string & v2)
 }
 
 
-static void testCompareVersions()
-{
-#define TEST(v1, v2, n) assert( \
-    compareVersions(v1, v2) == n && compareVersions(v2, v1) == -n)
-    TEST("1.0", "2.3", -1);
-    TEST("2.1", "2.3", -1);
-    TEST("2.3", "2.3", 0);
-    TEST("2.5", "2.3", 1);
-    TEST("3.1", "2.3", 1);
-    TEST("2.3.1", "2.3", 1);
-    TEST("2.3.1", "2.3a", 1);
-    TEST("2.3pre1", "2.3", -1);
-    TEST("2.3pre3", "2.3pre12", -1);
-    TEST("2.3a", "2.3c", -1);
-    TEST("2.3pre1", "2.3c", -1);
-    TEST("2.3pre1", "2.3q", -1);
-}
-
-
 DrvNames drvNamesFromArgs(const Strings & opArgs)
 {
     DrvNames result;

src/libexpr/nix.sdf

@@ -1,10 +1,13 @@
+%% Note: this SDF grammar is no longer used in the Nix expression
+%% parser and may not be up to date.
+
 definition
 
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% Top level syntax.
 
-module Nix
+module Main
 imports Nix-Exprs Nix-Layout
 
 
@@ -38,6 +41,7 @@ exports
     "with" Expr ";" Expr -> Expr {cons("With")}
 
     "rec" "{" Bind* "}" -> Expr {cons("Rec")}
+    "let" Bind* "in" Expr -> Expr {cons("Let")}
     "let" "{" Bind* "}" -> Expr {cons("LetRec")}
     "{" Bind* "}" -> Expr {cons("Attrs")}
 
@@ -102,7 +106,8 @@ exports
 
     [0-9]+ -> Int
 
-    "\"" ~[\n\"]* "\"" -> Str
+    "\"" (~[\"\\] | ("\\" ~[]) )* "\"" -> Str
+    "''" (~[\"\\] | ("\\" ~[]) )* "''" -> Str
 
     [a-zA-Z0-9\.\_\-\+]* ("/"[a-zA-Z0-9\.\_\-\+]+)+ -> Path
 

src/libexpr/nixexpr-ast.def

@@ -3,8 +3,7 @@ init initNixExprHelpers
 Pos | string int int | Pos |
 NoPos | | Pos |
 
-Function | ATermList Expr Pos | Expr |
-Function1 | string Expr Pos | Expr |
+Function | Pattern Expr Pos | Expr |
 Assert | Expr Expr Pos | Expr |
 With | Expr Expr Pos | Expr |
 If | Expr Expr Expr | Expr |
@@ -46,6 +45,9 @@ Int | int | Expr |
 Str | string ATermList | Expr |
 Str | string | Expr | ObsoleteStr
 
+# Internal to the parser, doesn't occur in ASTs.
+IndStr | string | Expr |
+
 # A path is a reference to a file system object that is to be copied
 # to the Nix store when used as a derivation attribute.  When it is
 # concatenated to a string (i.e., `str + path'), it is also copied and
@@ -64,7 +66,7 @@ PrimOp | int ATermBlob ATermList | Expr |
 Attrs | ATermList | Expr |
 Closed | Expr | Expr |
 Rec | ATermList ATermList | Expr |
-Bool | ATerm | Expr |
+Bool | ATermBool | Expr |
 Null | | Expr |
 
 Bind | string Expr Pos | ATerm |
@@ -73,18 +75,17 @@ Inherit | Expr ATermList Pos | ATerm |
 
 Scope | | Expr |
 
-Cell | int Expr | Expr |
+VarPat | string | Pattern |
+AttrsPat | ATermList ATermBool | Pattern | # bool = `...'
+AtPat | Pattern Pattern | Pattern |
 
-Formal | string ValidValues DefaultValue | ATerm |
-
-ValidValues | ATermList | ValidValues |
-UnrestrictedValues | | ValidValues |
+Formal | string DefaultValue | ATerm |
 
 DefaultValue | Expr | DefaultValue |
 NoDefaultValue | | DefaultValue |
 
-True | | ATerm |
-False | | ATerm |
+True | | ATermBool |
+False | | ATermBool |
 
 PrimOpDef | int ATermBlob | ATerm |
 
@@ -92,3 +93,4 @@ AttrRHS | Expr Pos | ATerm |
 
 eTrue = makeBool(makeTrue())
 eFalse = makeBool(makeFalse())
+sOverrides = toATerm("__overrides")

src/libexpr/nixexpr.cc

@@ -2,11 +2,12 @@
 #include "derivations.hh"
 #include "util.hh"
 #include "aterm.hh"
-#include "eval.hh" // !!! urgh
 
 #include "nixexpr-ast.hh"
 #include "nixexpr-ast.cc"
 
+#include <cstdlib>
+
 
 namespace nix {
     
@@ -109,16 +110,32 @@ Expr makeAttrs(const ATermMap & attrs)
 }
 
 
-extern unsigned int substs;
-extern unsigned int substsCached;
-extern bool closedTerms;
-extern bool substCache;
+static void varsBoundByPattern(ATermMap & map, Pattern pat)
+{
+    ATerm name;
+    ATermList formals;
+    Pattern pat1, pat2;
+    ATermBool ellipsis;
+    /* Use makeRemoved() so that it can be used directly in
+       substitute(). */
+    if (matchVarPat(pat, name))
+        map.set(name, makeRemoved());
+    else if (matchAttrsPat(pat, formals, ellipsis)) { 
+        for (ATermIterator i(formals); i; ++i) {
+            ATerm d1;
+            if (!matchFormal(*i, name, d1)) abort();
+            map.set(name, makeRemoved());
+        }
+    }
+    else if (matchAtPat(pat, pat1, pat2)) {
+        varsBoundByPattern(map, pat1);
+        varsBoundByPattern(map, pat2);
+    }
+    else abort();
+}
 
 
-static Expr substitute(ATermMap & done, const Substitution & subs, Expr e);
-
-
-static Expr substitute2(ATermMap & done, const Substitution & subs, Expr e)
+Expr substitute(const Substitution & subs, Expr e)
 {
     checkInterrupt();
 
@@ -126,77 +143,47 @@ static Expr substitute2(ATermMap & done, const Substitution & subs, Expr e)
 
     ATerm name, pos, e2;
 
-    substs++;
-
     /* As an optimisation, don't substitute in subterms known to be
        closed. */
-    if (closedTerms && matchClosed(e, e2)) return e;
+    if (matchClosed(e, e2)) return e;
 
     if (matchVar(e, name)) {
         Expr sub = subs.lookup(name);
+        if (sub == makeRemoved()) sub = 0;
         Expr wrapped;
         /* Add a "closed" wrapper around terms that aren't already
            closed.  The check is necessary to prevent repeated
            wrapping, e.g., closed(closed(closed(...))), which kills
            caching. */
-        return sub ? ((!closedTerms || matchClosed(sub, wrapped)) ? sub : makeClosed(sub)) : e;
+        return sub ? (matchClosed(sub, wrapped) ? sub : makeClosed(sub)) : e;
     }
 
     /* In case of a function, filter out all variables bound by this
        function. */
-    ATermList formals;
+    Pattern pat;
     ATerm body;
-    if (matchFunction(e, formals, body, pos)) {
-        ATermMap map(ATgetLength(formals));
-        for (ATermIterator i(formals); i; ++i) {
-            ATerm d1, d2;
-            if (!matchFormal(*i, name, d1, d2)) abort();
-            if (subs.lookup(name))
-                map.set(name, constRemoved);
-        }
-        if (map.size() == 0)
-            return makeFunction(
-                (ATermList) substitute(done, subs, (ATerm) formals),
-                substitute(done, subs, body), pos);
-        else {
-            Substitution subs2(&subs, &map);
-            ATermMap done2(128);
-            return makeFunction(
-                (ATermList) substitute(done2, subs2, (ATerm) formals),
-                substitute(done2, subs2, body), pos);
-        }
+    if (matchFunction(e, pat, body, pos)) {
+        ATermMap map(16);
+        varsBoundByPattern(map, pat);
+        Substitution subs2(&subs, &map);
+        return makeFunction(
+            (Pattern) substitute(subs2, (Expr) pat),
+            substitute(subs2, body), pos);
     }
 
-    if (matchFunction1(e, name, body, pos)) {
-        if (subs.lookup(name)) {
-            ATermMap map(1);
-            map.set(name, constRemoved);
-            ATermMap done2(128);
-            return makeFunction1(name, substitute(done2, Substitution(&subs, &map), body), pos);
-        } else
-            return makeFunction1(name, substitute(done, subs, body), pos);
-    }
-        
     /* Idem for a mutually recursive attribute set. */
     ATermList rbnds, nrbnds;
     if (matchRec(e, rbnds, nrbnds)) {
         ATermMap map(ATgetLength(rbnds) + ATgetLength(nrbnds));
         for (ATermIterator i(rbnds); i; ++i)
-            if (matchBind(*i, name, e2, pos) && subs.lookup(name))
-                map.set(name, constRemoved);
+            if (matchBind(*i, name, e2, pos)) map.set(name, makeRemoved());
+            else abort(); /* can't happen */
         for (ATermIterator i(nrbnds); i; ++i)
-            if (matchBind(*i, name, e2, pos) && subs.lookup(name))
-                map.set(name, constRemoved);
-        if (map.size() == 0)
-            return makeRec(
-                (ATermList) substitute(done, subs, (ATerm) rbnds),
-                (ATermList) substitute(done, subs, (ATerm) nrbnds));
-        else {
-            ATermMap done2(128);
-            return makeRec(
-                (ATermList) substitute(done2, Substitution(&subs, &map), (ATerm) rbnds),
-                (ATermList) substitute(done, subs, (ATerm) nrbnds));
-        }
+            if (matchBind(*i, name, e2, pos)) map.set(name, makeRemoved());
+            else abort(); /* can't happen */
+        return makeRec(
+            (ATermList) substitute(Substitution(&subs, &map), (ATerm) rbnds),
+            (ATermList) substitute(subs, (ATerm) nrbnds));
     }
 
     if (ATgetType(e) == AT_APPL) {
@@ -207,73 +194,7 @@ static Expr substitute2(ATermMap & done, const Substitution & subs, Expr e)
 
         for (int i = 0; i < arity; ++i) {
             ATerm arg = ATgetArgument(e, i);
-            args[i] = substitute(done, subs, arg);
-            if (args[i] != arg) changed = true;
-        }
-        
-        return changed ? (ATerm) ATmakeApplArray(fun, args) : e;
-    }
-
-    if (ATgetType(e) == AT_LIST) {
-        unsigned int len = ATgetLength((ATermList) e);
-        ATerm es[len];
-        ATermIterator i((ATermList) e);
-        bool changed = false;
-        for (unsigned int j = 0; i; ++i, ++j) {
-            es[j] = substitute(done, subs, *i);
-            if (es[j] != *i) changed = true;
-        }
-        if (!changed) return e;
-        ATermList out = ATempty;
-        for (unsigned int j = len; j; --j)
-            out = ATinsert(out, es[j - 1]);
-        return (ATerm) out;
-    }
-
-    return e;
-}
-
-
-static Expr substitute(ATermMap & done, const Substitution & subs, Expr e)
-{
-    Expr res = done[e];
-    if (substCache && res) {
-        substsCached++;
-        return res;
-    }
-    res = substitute2(done, subs, e);
-    done.set(e, res);
-    return res;
-}
-
-
-Expr substitute(const Substitution & subs, Expr e)
-{
-    ATermMap done(256);
-    return substitute(done, subs, e);
-}
-
-
-Expr allocCells(Expr e)
-{
-    checkInterrupt();
-
-    ATerm e2;
-    if (matchClosed(e, e2)) return e;
-
-    int i;
-    if (matchCell(e, i, e2))
-        return allocCell(allocCells(e2));
-
-    if (ATgetType(e) == AT_APPL) {
-        AFun fun = ATgetAFun(e);
-        int arity = ATgetArity(fun);
-        ATerm args[arity];
-        bool changed = false;
-
-        for (int i = 0; i < arity; ++i) {
-            ATerm arg = ATgetArgument(e, i);
-            args[i] = allocCells(arg);
+            args[i] = substitute(subs, arg);
             if (args[i] != arg) changed = true;
         }
         
@@ -285,7 +206,7 @@ Expr allocCells(Expr e)
         ATerm es[len];
         ATermIterator i((ATermList) e);
         for (unsigned int j = 0; i; ++i, ++j)
-            es[j] = allocCells(*i);
+            es[j] = substitute(subs, *i);
         ATermList out = ATempty;
         for (unsigned int j = len; j; --j)
             out = ATinsert(out, es[j - 1]);
@@ -307,38 +228,25 @@ static void checkVarDefs2(set<Expr> & done, const ATermMap & defs, Expr e)
     done.insert(e);
     
     ATerm name, pos, value;
-    ATermList formals;
     ATerm with, body;
     ATermList rbnds, nrbnds;
+    Pattern pat;
 
-    if (matchVar(e, name)) {
+    /* Closed terms don't have free variables, so we don't have to
+       check by definition. */
+    if (matchClosed(e, value)) return;
+    
+    else if (matchVar(e, name)) {
         if (!defs.get(name))
             throw EvalError(format("undefined variable `%1%'")
                 % aterm2String(name));
     }
 
-    else if (matchFunction(e, formals, body, pos)) {
+    else if (matchFunction(e, pat, body, pos)) {
         ATermMap defs2(defs);
-        for (ATermIterator i(formals); i; ++i) {
-            ATerm d1, d2;
-            if (!matchFormal(*i, name, d1, d2)) abort();
-            defs2.set(name, (ATerm) ATempty);
-        }
-        for (ATermIterator i(formals); i; ++i) {
-            ATerm valids, deflt;
-            set<Expr> done2;
-            if (!matchFormal(*i, name, valids, deflt)) abort();
-            checkVarDefs2(done, defs, valids);
-            checkVarDefs2(done2, defs2, deflt);
-        }
-        set<Expr> done2;
-        checkVarDefs2(done2, defs2, body);
-    }
-        
-    else if (matchFunction1(e, name, body, pos)) {
-        ATermMap defs2(defs);
-        defs2.set(name, (ATerm) ATempty);
+        varsBoundByPattern(defs2, pat);
         set<Expr> done2;
+        checkVarDefs2(done2, defs2, pat);
         checkVarDefs2(done2, defs2, body);
     }
         
@@ -452,17 +360,17 @@ Expr makeStr(const string & s, const PathSet & context)
 
 string showType(Expr e)
 {
-    ATerm t1, t2, t3;
+    ATerm t1, t2;
     ATermList l1;
     ATermBlob b1;
     int i1;
+    Pattern p1;
     if (matchStr(e, t1, l1)) return "a string";
     if (matchPath(e, t1)) return "a path";
     if (matchNull(e)) return "null";
     if (matchInt(e, i1)) return "an integer";
     if (matchBool(e, t1)) return "a boolean";
-    if (matchFunction(e, l1, t1, t2)) return "a function";
-    if (matchFunction1(e, t1, t2, t3)) return "a function";
+    if (matchFunction(e, p1, t1, t2)) return "a function";
     if (matchAttrs(e, l1)) return "an attribute set";
     if (matchList(e, l1)) return "a list";
     if (matchPrimOp(e, i1, b1, l1)) return "a partially applied built-in function";
@@ -495,18 +403,5 @@ string showValue(Expr e)
     return "<unknown>";
 }
 
-
-static unsigned int cellCount = 0;
-
-
-Expr allocCell(Expr e)
-{
-    if (cacheTerms != 2) return e;
-    int i;
-    Expr e2;
-    if (matchCell(e, i, e2)) return e;
-    return makeCell(cellCount++, e);
-}
-
  
 }

src/libexpr/nixexpr.hh

@@ -21,11 +21,10 @@ MakeError(TypeError, EvalError)
    property of the ATerm library allows us to implement caching of
    normals forms efficiently. */
 typedef ATerm Expr;
-
 typedef ATerm DefaultValue;
-typedef ATerm ValidValues;
-
 typedef ATerm Pos;
+typedef ATerm Pattern;
+typedef ATerm ATermBool;
 
 
 /* A STL vector of ATerms.  Should be used with great care since it's
@@ -34,9 +33,6 @@ typedef ATerm Pos;
 typedef vector<ATerm> ATermVector;
 
 
-extern Expr constRemoved;
-
-
 /* A substitution is a linked list of ATermMaps that map names to
    identifiers.  We use a list of ATermMaps rather than a single to
    make it easy to grow or shrink a substitution when entering a
@@ -56,8 +52,7 @@ struct Substitution
     {
         Expr x;
         for (const Substitution * s(this); s; s = s->prev)
-            if ((x = s->map->get(name)))
-                return x == constRemoved ? 0 : x;
+            if ((x = s->map->get(name))) return x;
         return 0;
     }
 };
@@ -120,11 +115,6 @@ string showType(Expr e);
 
 string showValue(Expr e);
 
-
-Expr allocCell(Expr e); // make an updateable cell (for simulating conventional laziness)
-
-Expr allocCells(Expr e); // re-allocate all cells in e
-
  
 }
 

src/libexpr/parser.y

@@ -57,7 +57,7 @@ static Expr fixAttrs(int recursive, ATermList as)
             bool fromScope = matchScope(src);
             for (ATermIterator j(names); j; ++j) {
                 Expr rhs = fromScope ? makeVar(*j) : makeSelect(src, *j);
-                *is = ATinsert(*is, makeBind(*j, allocCell(rhs), pos));
+                *is = ATinsert(*is, makeBind(*j, rhs, pos));
             }
         } else bs = ATinsert(bs, *i);
     }
@@ -68,15 +68,104 @@ static Expr fixAttrs(int recursive, ATermList as)
 }
 
 
+static Expr stripIndentation(ATermList es)
+{
+    if (es == ATempty) return makeStr("");
+    
+    /* Figure out the minimum indentation.  Note that by design
+       whitespace-only final lines are not taken into account.  (So
+       the " " in "\n ''" is ignored, but the " " in "\n foo''" is.) */
+    bool atStartOfLine = true; /* = seen only whitespace in the current line */
+    unsigned int minIndent = 1000000;
+    unsigned int curIndent = 0;
+    ATerm e;
+    for (ATermIterator i(es); i; ++i) {
+        if (!matchIndStr(*i, e)) {
+            /* Anti-quotations end the current start-of-line whitespace. */
+            if (atStartOfLine) {
+                atStartOfLine = false;
+                if (curIndent < minIndent) minIndent = curIndent;
+            }
+            continue;
+        }
+        string s = aterm2String(e);
+        for (unsigned int j = 0; j < s.size(); ++j) {
+            if (atStartOfLine) {
+                if (s[j] == ' ')
+                    curIndent++;
+                else if (s[j] == '\n') {
+                    /* Empty line, doesn't influence minimum
+                       indentation. */
+                    curIndent = 0;
+                } else {
+                    atStartOfLine = false;
+                    if (curIndent < minIndent) minIndent = curIndent;
+                }
+            } else if (s[j] == '\n') {
+                atStartOfLine = true;
+                curIndent = 0;
+            }
+        }
+    }
+
+    /* Strip spaces from each line. */
+    ATermList es2 = ATempty;
+    atStartOfLine = true;
+    unsigned int curDropped = 0;
+    unsigned int n = ATgetLength(es);
+    for (ATermIterator i(es); i; ++i, --n) {
+        if (!matchIndStr(*i, e)) {
+            atStartOfLine = false;
+            curDropped = 0;
+            es2 = ATinsert(es2, *i);
+            continue;
+        }
+        
+        string s = aterm2String(e);
+        string s2;
+        for (unsigned int j = 0; j < s.size(); ++j) {
+            if (atStartOfLine) {
+                if (s[j] == ' ') {
+                    if (curDropped++ >= minIndent)
+                        s2 += s[j];
+                }
+                else if (s[j] == '\n') {
+                    curDropped = 0;
+                    s2 += s[j];
+                } else {
+                    atStartOfLine = false;
+                    curDropped = 0;
+                    s2 += s[j];
+                }
+            } else {
+                s2 += s[j];
+                if (s[j] == '\n') atStartOfLine = true;
+            }
+        }
+
+        /* Remove the last line if it is empty and consists only of
+           spaces. */
+        if (n == 1) {
+            unsigned int p = s2.find_last_of('\n');
+            if (p != string::npos && s2.find_first_not_of(' ', p + 1) == string::npos)
+                s2 = string(s2, 0, p + 1);
+        }
+            
+        es2 = ATinsert(es2, makeStr(s2));
+    }
+
+    return makeConcatStrings(ATreverse(es2));
+}
+
+
 void backToString(yyscan_t scanner);
+void backToIndString(yyscan_t scanner);
 
 
-extern bool posInfo;
- 
 static Pos makeCurPos(YYLTYPE * loc, ParseData * data)
 {
-    return posInfo ? makePos(toATerm(data->path),
-        loc->first_line, loc->first_column) : makeNoPos();
+    return makePos(toATerm(data->path),
+        loc->first_line, loc->first_column);
 }
 
 #define CUR_POS makeCurPos(yylocp, data)
@@ -119,14 +208,22 @@ static void freeAndUnprotect(void * p)
 %union {
   ATerm t;
   ATermList ts;
+  struct {
+    ATermList formals;
+    bool ellipsis;
+  } formals;
 }
 
 %type <t> start expr expr_function expr_if expr_op
 %type <t> expr_app expr_select expr_simple bind inheritsrc formal
-%type <ts> binds ids expr_list formals string_parts
-%token <t> ID INT STR PATH URI
+%type <t> pattern pattern2
+%type <ts> binds ids expr_list string_parts ind_string_parts
+%type <formals> formals
+%token <t> ID INT STR IND_STR PATH URI
 %token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL
 %token DOLLAR_CURLY /* == ${ */
+%token IND_STRING_OPEN IND_STRING_CLOSE
+%token ELLIPSIS
 
 %nonassoc IMPL
 %left OR
@@ -146,10 +243,8 @@ start: expr { data->result = $1; };
 expr: expr_function;
 
 expr_function
-  : '{' formals '}' ':' expr_function
-    { $$ = makeFunction($2, $5, CUR_POS); }
-  | ID ':' expr_function
-    { $$ = makeFunction1($1, $3, CUR_POS); }
+  : pattern ':' expr_function
+    { $$ = makeFunction($1, $3, CUR_POS); }
   | ASSERT expr ';' expr_function
     { $$ = makeAssert($2, $4, CUR_POS); }
   | WITH expr ';' expr_function
@@ -201,6 +296,9 @@ expr_simple
       else if (ATgetNext($2) == ATempty) $$ = ATgetFirst($2);
       else $$ = makeConcatStrings(ATreverse($2));
   }
+  | IND_STRING_OPEN ind_string_parts IND_STRING_CLOSE {
+      $$ = stripIndentation(ATreverse($2));
+  }
   | PATH { $$ = makePath(toATerm(absPath(aterm2String($1), data->basePath))); }
   | URI { $$ = makeStr($1, ATempty); }
   | '(' expr ')' { $$ = $2; }
@@ -221,6 +319,22 @@ string_parts
   | { $$ = ATempty; }
   ;
 
+ind_string_parts
+  : ind_string_parts IND_STR { $$ = ATinsert($1, $2); }
+  | ind_string_parts DOLLAR_CURLY expr '}' { backToIndString(scanner); $$ = ATinsert($1, $3); }
+  | { $$ = ATempty; }
+  ;
+
+pattern
+  : pattern2 '@' pattern { $$ = makeAtPat($1, $3); }
+  | pattern2
+  ;
+
+pattern2
+  : ID { $$ = makeVarPat($1); }
+  | '{' formals '}' { $$ = makeAttrsPat($2.formals, $2.ellipsis ? eTrue : eFalse); }
+  ;
+
 binds
   : binds bind { $$ = ATinsert($1, $2); }
   | { $$ = ATempty; }
@@ -228,7 +342,7 @@ binds
 
 bind
   : ID '=' expr ';'
-    { $$ = makeBind($1, allocCell($3), CUR_POS); }
+    { $$ = makeBind($1, $3, CUR_POS); }
   | INHERIT inheritsrc ids ';'
     { $$ = makeInherit($2, $3, CUR_POS); }
   ;
@@ -249,15 +363,19 @@ expr_list
   ;
 
 formals
-  : formal ',' formals { $$ = ATinsert($3, $1); } /* idem - right recursive */
-  | formal { $$ = ATinsert(ATempty, $1); }
-  | { $$ = ATempty; }
+  : formal ',' formals /* idem - right recursive */
+    { $$.formals = ATinsert($3.formals, $1); $$.ellipsis = $3.ellipsis; }
+  | formal
+    { $$.formals = ATinsert(ATempty, $1); $$.ellipsis = false; }
+  |
+    { $$.formals = ATempty; $$.ellipsis = false; }
+  | ELLIPSIS
+    { $$.formals = ATempty; $$.ellipsis = true; }
   ;
 
 formal
-  : ID { $$ = makeFormal($1, makeUnrestrictedValues(), makeNoDefaultValue()); }
-  | ID ':' '[' expr_list ']' { $$ = makeFormal($1, makeValidValues($4), makeNoDefaultValue()); }
-  | ID '?' expr { $$ = makeFormal($1, makeUnrestrictedValues(), makeDefaultValue($3)); }
+  : ID { $$ = makeFormal($1, makeNoDefaultValue()); }
+  | ID '?' expr { $$ = makeFormal($1, makeDefaultValue($3)); }
   ;
   
 %%
@@ -289,22 +407,43 @@ static void checkAttrs(ATermMap & names, ATermList bnds)
 }
 
 
-static void checkAttrSets(ATerm e)
+static void checkPatternVars(ATerm pos, ATermMap & map, Pattern pat)
 {
+    ATerm name;
     ATermList formals;
-    ATerm body, pos;
-    if (matchFunction(e, formals, body, pos)) {
-        ATermMap names(ATgetLength(formals));
+    Pattern pat1, pat2;
+    ATermBool ellipsis;
+    if (matchVarPat(pat, name)) {
+        if (map.get(name))
+            throw EvalError(format("duplicate formal function argument `%1%' at %2%")
+                % aterm2String(name) % showPos(pos));
+        map.set(name, name);
+    }
+    else if (matchAttrsPat(pat, formals, ellipsis)) { 
         for (ATermIterator i(formals); i; ++i) {
-            ATerm name;
-            ATerm d1, d2;
-            if (!matchFormal(*i, name, d1, d2)) abort();
-            if (names.get(name))
+            ATerm d1;
+            if (!matchFormal(*i, name, d1)) abort();
+            if (map.get(name))
                 throw EvalError(format("duplicate formal function argument `%1%' at %2%")
                     % aterm2String(name) % showPos(pos));
-            names.set(name, name);
+            map.set(name, name);
         }
     }
+    else if (matchAtPat(pat, pat1, pat2)) {
+        checkPatternVars(pos, map, pat1);
+        checkPatternVars(pos, map, pat2);
+    }
+    else abort();
+}
+
+
+static void checkAttrSets(ATerm e)
+{
+    ATerm pat, body, pos;
+    if (matchFunction(e, pat, body, pos)) {
+        ATermMap map(16);
+        checkPatternVars(pos, map, pat);
+    }
 
     ATermList bnds;
     if (matchAttrs(e, bnds)) {
@@ -385,13 +524,8 @@ Expr parseExprFromFile(EvalState & state, Path path)
     if (S_ISDIR(st.st_mode))
         path = canonPath(path + "/default.nix");
 
-    Expr cached = state.parsings.get(toATerm(path));
-    if (cached) return cached;
-
     /* Read and parse the input file. */
-    cached = parse(state, readFile(path).c_str(), path, dirOf(path));
-    state.parsings.set(toATerm(path), cached);
-    return cached;
+    return parse(state, readFile(path).c_str(), path, dirOf(path));
 }
 
 

src/libexpr/primops.cc

@@ -6,6 +6,8 @@
 #include "archive.hh"
 #include "expr-to-xml.hh"
 #include "nixexpr-ast.hh"
+#include "parser.hh"
+#include "names.hh"
 
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -118,67 +120,13 @@ static Expr prim_isNull(EvalState & state, const ATermVector & args)
 static Expr prim_isFunction(EvalState & state, const ATermVector & args)
 {
     Expr e = evalExpr(state, args[0]);
-    ATermList formals;
-    ATerm name, body, pos;
-    return makeBool(
-        matchFunction(e, formals, body, pos) ||
-        matchFunction1(e, name, body, pos));
+    Pattern pat;
+    ATerm body, pos;
+    return makeBool(matchFunction(e, pat, body, pos));
 }
 
 
-static Path findDependency(Path dir, string dep)
-{
-    if (dep[0] == '/') throw EvalError(
-        format("illegal absolute dependency `%1%'") % dep);
-
-    Path p = canonPath(dir + "/" + dep);
-
-    if (pathExists(p))
-        return p;
-    else
-        return "";
-}
-
-
-/* Make path `p' relative to directory `pivot'.  E.g.,
-   relativise("/a/b/c", "a/b/x/y") => "../x/y".  Both input paths
-   should be in absolute canonical form. */
-static string relativise(Path pivot, Path p)
-{
-    assert(pivot.size() > 0 && pivot[0] == '/');
-    assert(p.size() > 0 && p[0] == '/');
-        
-    if (pivot == p) return ".";
-
-    /* `p' is in `pivot'? */
-    Path pivot2 = pivot + "/";
-    if (p.substr(0, pivot2.size()) == pivot2) {
-        return p.substr(pivot2.size());
-    }
-
-    /* Otherwise, `p' is in a parent of `pivot'.  Find up till which
-       path component `p' and `pivot' match, and add an appropriate
-       number of `..' components. */
-    string::size_type i = 1;
-    while (1) {
-        string::size_type j = pivot.find('/', i);
-        if (j == string::npos) break;
-        j++;
-        if (pivot.substr(0, j) != p.substr(0, j)) break;
-        i = j;
-    }
-
-    string prefix;
-    unsigned int slashes = count(pivot.begin() + i, pivot.end(), '/') + 1;
-    while (slashes--) {
-        prefix += "../";
-    }
-
-    return prefix + p.substr(i);
-}
-
-
-static Expr prim_dependencyClosure(EvalState & state, const ATermVector & args)
+static Expr prim_genericClosure(EvalState & state, const ATermVector & args)
 {
     startNest(nest, lvlDebug, "finding dependencies");
 
@@ -189,87 +137,40 @@ static Expr prim_dependencyClosure(EvalState & state, const ATermVector & args)
     if (!startSet) throw EvalError("attribute `startSet' required");
     ATermList startSet2 = evalList(state, startSet);
 
-    Path pivot;
-    PathSet workSet;
-    for (ATermIterator i(startSet2); i; ++i) {
-        PathSet context; /* !!! what to do? */
-        Path p = coerceToPath(state, *i, context);
-        workSet.insert(p);
-        pivot = dirOf(p);
-    }
+    set<Expr> workSet; // !!! gc roots
+    for (ATermIterator i(startSet2); i; ++i) workSet.insert(*i);
 
-    /* Get the search path. */
-    PathSet searchPath;
-    Expr e = queryAttr(attrs, "searchPath");
-    if (e) {
-        ATermList list = evalList(state, e);
-        for (ATermIterator i(list); i; ++i) {
-            PathSet context; /* !!! what to do? */
-            Path p = coerceToPath(state, *i, context);
-            searchPath.insert(p);
-        }
-    }
-
-    Expr scanner = queryAttr(attrs, "scanner");
-    if (!scanner) throw EvalError("attribute `scanner' required");
+    /* Get the operator. */
+    Expr op = queryAttr(attrs, "operator");
+    if (!op) throw EvalError("attribute `operator' required");
     
-    /* Construct the dependency closure by querying the dependency of
-       each path in `workSet', adding the dependencies to
-       `workSet'. */
-    PathSet doneSet;
+    /* Construct the closure by applying the operator to element of
+       `workSet', adding the result to `workSet', continuing until
+       no new elements are found. */
+    ATermList res = ATempty;
+    set<Expr> doneKeys; // !!! gc roots
     while (!workSet.empty()) {
-	Path path = *(workSet.begin());
-	workSet.erase(path);
+	Expr e = *(workSet.begin());
+	workSet.erase(e);
 
-	if (doneSet.find(path) != doneSet.end()) continue;
-        doneSet.insert(path);
+        e = strictEvalExpr(state, e);
 
-        try {
-            
-            /* Call the `scanner' function with `path' as argument. */
-            debug(format("finding dependencies in `%1%'") % path);
-            ATermList deps = evalList(state, makeCall(scanner, makeStr(path)));
+        Expr key = queryAttr(e, "key");
+        if (!key) throw EvalError("attribute `key' required");
 
-            /* Try to find the dependencies relative to the `path'. */
-            for (ATermIterator i(deps); i; ++i) {
-                string s = evalStringNoCtx(state, *i);
-                
-                Path dep = findDependency(dirOf(path), s);
+	if (doneKeys.find(key) != doneKeys.end()) continue;
+        doneKeys.insert(key);
+        res = ATinsert(res, e);
+        
+        /* Call the `operator' function with `e' as argument. */
+        ATermList res = evalList(state, makeCall(op, e));
 
-                if (dep == "") {
-                    for (PathSet::iterator j = searchPath.begin();
-                         j != searchPath.end(); ++j)
-                    {
-                        dep = findDependency(*j, s);
-                        if (dep != "") break;
-                    }
-                }
-                
-                if (dep == "")
-                    debug(format("did NOT find dependency `%1%'") % s);
-                else {
-                    debug(format("found dependency `%1%'") % dep);
-                    workSet.insert(dep);
-                }
-            }
-
-        } catch (Error & e) {
-            e.addPrefix(format("while finding dependencies in `%1%':\n")
-                % path);
-            throw;
-        }
+        /* Try to find the dependencies relative to the `path'. */
+        for (ATermIterator i(res); i; ++i)
+            workSet.insert(evalExpr(state, *i));
     }
 
-    /* Return a list of the dependencies we've just found. */
-    ATermList deps = ATempty;
-    for (PathSet::iterator i = doneSet.begin(); i != doneSet.end(); ++i) {
-        deps = ATinsert(deps, makeStr(relativise(pivot, *i)));
-        deps = ATinsert(deps, makeStr(*i));
-    }
-
-    debug(format("dependency list is `%1%'") % makeList(deps));
-    
-    return makeList(deps);
+    return makeList(res);
 }
 
 
@@ -296,26 +197,18 @@ static Expr prim_getEnv(EvalState & state, const ATermVector & args)
     return makeStr(getEnv(name));
 }
 
-/* for debugging purposes. print the first arg on stdout (perhaps stderr should be used?)
- * and return the second
+
+/* Evaluate the first expression, and print its abstract syntax tree
+   on standard error.  Then return the second expression.  Useful for
+   debugging.
  */
 static Expr prim_trace(EvalState & state, const ATermVector & args)
 {
-    //string str = evalStringNoCtx(state, args[0]);
-
-    Expr a = evalExpr(state, args[0]);
-    printf("traced value: %s\n", atPrint(a).c_str());
+    Expr e = evalExpr(state, args[0]);
+    printMsg(lvlError, format("trace: %1%") % e);
     return evalExpr(state, args[1]);
 }
 
-static Expr prim_relativise(EvalState & state, const ATermVector & args)
-{
-    PathSet context; /* !!! what to do? */
-    Path pivot = coerceToPath(state, args[0], context);
-    Path path = coerceToPath(state, args[1], context);
-    return makeStr(relativise(pivot, path));
-}
-
 
 /*************************************************************
  * Derivations
@@ -564,7 +457,7 @@ static Expr prim_derivationLazy(EvalState & state, const ATermVector & args)
     attrs.set(toATerm("type"),
         makeAttrRHS(makeStr("derivation"), makeNoPos()));
 
-    Expr drvStrict = allocCell(makeCall(makeVar(toATerm("derivation!")), eAttrs));
+    Expr drvStrict = makeCall(makeVar(toATerm("derivation!")), eAttrs);
 
     attrs.set(toATerm("outPath"),
         makeAttrRHS(makeSelect(drvStrict, toATerm("outPath")), makeNoPos()));
@@ -589,6 +482,27 @@ static Expr prim_toPath(EvalState & state, const ATermVector & args)
 }
 
 
+/* Allow a valid store path to be used in an expression.  This is
+   useful in some generated expressions such as in nix-push, which
+   generates a call to a function with an already existing store path
+   as argument.  You don't want to use `toPath' here because it copies
+   the path to the Nix store, which yields a copy like
+   /nix/store/newhash-oldhash-oldname.  In the past, `toPath' had
+   special case behaviour for store paths, but that created weird
+   corner cases. */
+static Expr prim_storePath(EvalState & state, const ATermVector & args)
+{
+    PathSet context;
+    Path path = canonPath(coerceToPath(state, args[0], context));
+    if (!isInStore(path))
+        throw EvalError(format("path `%1%' is not in the Nix store") % path);
+    if (!store->isValidPath(path))
+        throw EvalError(format("store path `%1%' is not valid") % path);
+    context.insert(toStorePath(path));
+    return makeStr(path, context);
+}
+
+
 static Expr prim_pathExists(EvalState & state, const ATermVector & args)
 {
     PathSet context;
@@ -621,6 +535,17 @@ static Expr prim_dirOf(EvalState & state, const ATermVector & args)
 }
 
 
+/* Return the contents of a file as a string. */
+static Expr prim_readFile(EvalState & state, const ATermVector & args)
+{
+    PathSet context;
+    Path path = coerceToPath(state, args[0], context);
+    if (!context.empty())
+        throw EvalError(format("string `%1%' cannot refer to other paths") % path);
+    return makeStr(readFile(path));
+}
+
+
 /*************************************************************
  * Creating files
  *************************************************************/
@@ -773,7 +698,7 @@ static Expr prim_listToAttrs(EvalState & state, const ATermVector & args)
                 Expr e = evalExpr(state, makeSelect(evaledExpr, toATerm("name")));
                 string attr = evalStringNoCtx(state,e);
                 Expr r = makeSelect(evaledExpr, toATerm("value"));
-                res.set(toATerm(attr), makeAttrRHS(allocCell(r), makeNoPos()));
+                res.set(toATerm(attr), makeAttrRHS(r, makeNoPos()));
             }
             else
                 throw TypeError(format("list element in `listToAttrs' is %s, expected a set { name = \"<name>\"; value = <value>; }")
@@ -788,6 +713,7 @@ static Expr prim_listToAttrs(EvalState & state, const ATermVector & args)
     }
 }
 
+
 static Expr prim_removeAttrs(EvalState & state, const ATermVector & args)
 {
     ATermMap attrs;
@@ -802,13 +728,15 @@ static Expr prim_removeAttrs(EvalState & state, const ATermVector & args)
     return makeAttrs(attrs);
 }
 
-/* Determine whether the argument is a list. */
+
+/* Determine whether the argument is an attribute set. */
 static Expr prim_isAttrs(EvalState & state, const ATermVector & args)
 {
     ATermList list;
     return makeBool(matchAttrs(evalExpr(state, args[0]), list));
 }
 
+
 /*************************************************************
  * Lists
  *************************************************************/
@@ -857,6 +785,14 @@ static Expr prim_map(EvalState & state, const ATermVector & args)
 }
 
 
+/* Return the length of a list.  This is an O(1) time operation. */
+static Expr prim_length(EvalState & state, const ATermVector & args)
+{
+    ATermList list = evalList(state, args[0]);
+    return makeInt(ATgetLength(list));
+}
+
+
 /*************************************************************
  * Integer arithmetic
  *************************************************************/
@@ -878,6 +814,23 @@ static Expr prim_sub(EvalState & state, const ATermVector & args)
 }
 
 
+static Expr prim_mul(EvalState & state, const ATermVector & args)
+{
+    int i1 = evalInt(state, args[0]);
+    int i2 = evalInt(state, args[1]);
+    return makeInt(i1 * i2);
+}
+
+
+static Expr prim_div(EvalState & state, const ATermVector & args)
+{
+    int i1 = evalInt(state, args[0]);
+    int i2 = evalInt(state, args[1]);
+    if (i2 == 0) throw EvalError("division by zero");
+    return makeInt(i1 / i2);
+}
+
+
 static Expr prim_lessThan(EvalState & state, const ATermVector & args)
 {
     int i1 = evalInt(state, args[0]);
@@ -902,8 +855,8 @@ static Expr prim_toString(EvalState & state, const ATermVector & args)
 }
 
 
-/* `substr start len str' returns the substring of `str' starting at
-   character position `min(start, stringLength str)' inclusive and
+/* `substring start len str' returns the substring of `str' starting
+   at character position `min(start, stringLength str)' inclusive and
    ending at `min(start + len, stringLength str)'.  `start' must be
    non-negative. */
 static Expr prim_substring(EvalState & state, const ATermVector & args)
@@ -927,14 +880,58 @@ static Expr prim_stringLength(EvalState & state, const ATermVector & args)
 }
 
 
+static Expr prim_unsafeDiscardStringContext(EvalState & state, const ATermVector & args)
+{
+    PathSet context;
+    string s = coerceToString(state, args[0], context);
+    return makeStr(s, PathSet());
+}
+
+
+/* Expression serialization/deserialization */
+
+
+static Expr prim_exprToString(EvalState & state, const ATermVector & args)
+{
+    /* !!! this disregards context */
+    return makeStr(atPrint(evalExpr(state, args[0])));
+}
+
+
+static Expr prim_stringToExpr(EvalState & state, const ATermVector & args)
+{
+    /* !!! this can introduce arbitrary garbage terms in the
+       evaluator! */;
+    string s;
+    PathSet l;
+    if (!matchStr(evalExpr(state, args[0]), s, l))
+        throw EvalError("stringToExpr needs string argument!");
+    return ATreadFromString(s.c_str());
+}
+
+
 /*************************************************************
- * Strictness
+ * Versions
  *************************************************************/
 
 
-static Expr prim_strict(EvalState & state, const ATermVector & args)
+static Expr prim_parseDrvName(EvalState & state, const ATermVector & args)
 {
-    return evalExpr(state, makeCall(args[0], evalExpr(state, args[1])));
+    string name = evalStringNoCtx(state, args[0]);
+    DrvName parsed(name);
+    ATermMap attrs(2);
+    attrs.set(toATerm("name"), makeAttrRHS(makeStr(parsed.name), makeNoPos()));
+    attrs.set(toATerm("version"), makeAttrRHS(makeStr(parsed.version), makeNoPos()));
+    return makeAttrs(attrs);
+}
+
+
+static Expr prim_compareVersions(EvalState & state, const ATermVector & args)
+{
+    string version1 = evalStringNoCtx(state, args[0]);
+    string version2 = evalStringNoCtx(state, args[1]);
+    int d = compareVersions(version1, version2);
+    return makeInt(d);
 }
 
 
@@ -958,13 +955,15 @@ void EvalState::addPrimOps()
     addPrimOp("import", 1, prim_import);
     addPrimOp("isNull", 1, prim_isNull);
     addPrimOp("__isFunction", 1, prim_isFunction);
-    addPrimOp("dependencyClosure", 1, prim_dependencyClosure);
+    addPrimOp("__genericClosure", 1, prim_genericClosure);
     addPrimOp("abort", 1, prim_abort);
     addPrimOp("throw", 1, prim_throw);
     addPrimOp("__getEnv", 1, prim_getEnv);
     addPrimOp("__trace", 2, prim_trace);
-
-    addPrimOp("relativise", 2, prim_relativise);
+    
+    // Expr <-> String
+    addPrimOp("__exprToString", 1, prim_exprToString);
+    addPrimOp("__stringToExpr", 1, prim_stringToExpr);
 
     // Derivations
     addPrimOp("derivation!", 1, prim_derivationStrict);
@@ -972,9 +971,11 @@ void EvalState::addPrimOps()
 
     // Paths
     addPrimOp("__toPath", 1, prim_toPath);
+    addPrimOp("__storePath", 1, prim_storePath);
     addPrimOp("__pathExists", 1, prim_pathExists);
     addPrimOp("baseNameOf", 1, prim_baseNameOf);
     addPrimOp("dirOf", 1, prim_dirOf);
+    addPrimOp("__readFile", 1, prim_readFile);
 
     // Creating files
     addPrimOp("__toXML", 1, prim_toXML);
@@ -994,19 +995,24 @@ void EvalState::addPrimOps()
     addPrimOp("__head", 1, prim_head);
     addPrimOp("__tail", 1, prim_tail);
     addPrimOp("map", 2, prim_map);
+    addPrimOp("__length", 1, prim_length);
 
     // Integer arithmetic
     addPrimOp("__add", 2, prim_add);
     addPrimOp("__sub", 2, prim_sub);
+    addPrimOp("__mul", 2, prim_mul);
+    addPrimOp("__div", 2, prim_div);
     addPrimOp("__lessThan", 2, prim_lessThan);
 
     // String manipulation
     addPrimOp("toString", 1, prim_toString);
     addPrimOp("__substring", 3, prim_substring);
     addPrimOp("__stringLength", 1, prim_stringLength);
+    addPrimOp("__unsafeDiscardStringContext", 1, prim_unsafeDiscardStringContext);
 
-    // Strictness
-    addPrimOp("strict", 2, prim_strict);
+    // Versions
+    addPrimOp("__parseDrvName", 1, prim_parseDrvName);
+    addPrimOp("__compareVersions", 2, prim_compareVersions);
 }
 
 

src/libmain/shared.cc

@@ -4,6 +4,7 @@
 #include "globals.hh"
 #include "store-api.hh"
 #include "util.hh"
+#include "misc.hh"
 
 #include <iostream>
 #include <cctype>
@@ -49,6 +50,34 @@ void printGCWarning()
 }
 
 
+void printMissing(const PathSet & paths)
+{
+    unsigned long long downloadSize;
+    PathSet willBuild, willSubstitute, unknown;
+    queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize);
+
+    if (!willBuild.empty()) {
+        printMsg(lvlInfo, format("the following derivations will be built:"));
+        foreach (PathSet::iterator, i, willBuild)
+            printMsg(lvlInfo, format("  %1%") % *i);
+    }
+
+    if (!willSubstitute.empty()) {
+        printMsg(lvlInfo, format("the following paths will be downloaded/copied (%.2f MiB):") %
+            (downloadSize / (1024.0 * 1024.0)));
+        foreach (PathSet::iterator, i, willSubstitute)
+            printMsg(lvlInfo, format("  %1%") % *i);
+    }
+
+    if (!unknown.empty()) {
+        printMsg(lvlInfo, format("don't know how to build the following paths%1%:")
+            % (readOnlyMode ? " (may be caused by read-only store access)" : ""));
+        foreach (PathSet::iterator, i, unknown)
+            printMsg(lvlInfo, format("  %1%") % *i);
+    }
+}
+
+
 static void setLogType(string lt)
 {
     if (lt == "pretty") logType = ltPretty;
@@ -58,27 +87,18 @@ static void setLogType(string lt)
 }
 
 
-static unsigned int getIntArg(const string & opt,
+unsigned long long getIntArg(const string & opt,
     Strings::iterator & i, const Strings::iterator & end)
 {
     ++i;
     if (i == end) throw UsageError(format("`%1%' requires an argument") % opt);
-    int n;
+    long long n;
     if (!string2Int(*i, n) || n < 0)
         throw UsageError(format("`%1%' requires a non-negative integer") % opt);
     return n;
 }
 
 
-struct RemoveTempRoots 
-{
-    ~RemoveTempRoots()
-    {
-        removeTempRoots();
-    }
-};
-
-
 void initDerivationsHelpers();
 
 
@@ -99,6 +119,12 @@ static void closeStore()
 }
 
 
+RemoveTempRoots::~RemoveTempRoots()
+{
+    removeTempRoots();
+}
+
+
 /* Initialize and reorder arguments, then call the actual argument
    processor. */
 static void initAndRun(int argc, char * * argv)
@@ -112,11 +138,13 @@ static void initAndRun(int argc, char * * argv)
     nixConfDir = canonPath(getEnv("NIX_CONF_DIR", NIX_CONF_DIR));
     nixLibexecDir = canonPath(getEnv("NIX_LIBEXEC_DIR", NIX_LIBEXEC_DIR));
     nixBinDir = canonPath(getEnv("NIX_BIN_DIR", NIX_BIN_DIR));
+    nixChrootsDir = canonPath(getEnv("NIX_CHROOTS_DIR", nixStateDir + "/chroots"));
 
     string subs = getEnv("NIX_SUBSTITUTERS", "default");
-    if (subs == "default")
-        substituters.push_back(nixLibexecDir + "/nix/download-using-manifests.pl");
-    else
+    if (subs == "default") {
+        substituters.push_back(nixLibexecDir + "/nix/substituters/copy-from-other-stores.pl");
+        substituters.push_back(nixLibexecDir + "/nix/substituters/download-using-manifests.pl");
+    } else
         substituters = tokenizeString(subs, ":");
 
     /* Get some settings from the configuration file. */
@@ -192,6 +220,8 @@ static void initAndRun(int argc, char * * argv)
             ; /* !!! obsolete - remove eventually */
         else if (arg == "--no-build-output" || arg == "-Q")
             buildVerbosity = lvlVomit;
+        else if (arg == "--print-build-trace")
+            printBuildTrace = true;
         else if (arg == "--help") {
             printHelp();
             return;
@@ -212,12 +242,14 @@ static void initAndRun(int argc, char * * argv)
             readOnlyMode = true;
         else if (arg == "--max-silent-time")
             maxSilentTime = getIntArg(arg, i, args.end());
+        else if (arg == "--no-build-hook")
+            useBuildHook = false;
         else remaining.push_back(arg);
     }
 
     /* Automatically clean up the temporary roots file when we
        exit. */
-    RemoveTempRoots removeTempRoots; /* unused variable - don't remove */
+    RemoveTempRoots removeTempRoots __attribute__((unused));
 
     /* Make sure that the database gets closed properly, even if
        terminate() is called (which happens sometimes due to bugs in

src/libmain/shared.hh

@@ -26,6 +26,11 @@ namespace nix {
 Path makeRootName(const Path & gcRoot, int & counter);
 void printGCWarning();
 
+void printMissing(const PathSet & paths);
+
+unsigned long long getIntArg(const string & opt,
+    Strings::iterator & i, const Strings::iterator & end);
+
 /* Whether we're running setuid. */
 extern bool setuidMode;
 
@@ -33,6 +38,11 @@ extern volatile ::sig_atomic_t blockInt;
 
 MakeError(UsageError, nix::Error);
 
+struct RemoveTempRoots 
+{
+    ~RemoveTempRoots();    
+};
+
 }
 
 

src/libstore/Makefile.am

@@ -1,13 +1,14 @@
 pkglib_LTLIBRARIES = libstore.la
 
 libstore_la_SOURCES = \
- store-api.cc local-store.cc remote-store.cc derivations.cc build.cc misc.cc \
- globals.cc db.cc references.cc pathlocks.cc gc.cc 
+  store-api.cc local-store.cc remote-store.cc derivations.cc build.cc misc.cc \
+  globals.cc db.cc references.cc pathlocks.cc gc.cc upgrade-schema.cc \
+  optimise-store.cc
 
 pkginclude_HEADERS = \
- store-api.hh local-store.hh remote-store.hh derivations.hh misc.hh \
- globals.hh db.hh references.hh pathlocks.hh \
- worker-protocol.hh
+  store-api.hh local-store.hh remote-store.hh derivations.hh misc.hh \
+  globals.hh db.hh references.hh pathlocks.hh \
+  worker-protocol.hh
 
 libstore_la_LIBADD = ../libutil/libutil.la ../boost/format/libformat.la
 

src/libstore/db.cc

@@ -1,3 +1,7 @@
+#include "config.h"
+
+#ifdef OLD_DB_COMPAT
+
 #include "db.hh"
 #include "util.hh"
 #include "pathlocks.hh"
@@ -466,3 +470,5 @@ void Database::clearTable(const Transaction & txn, TableId table)
 
 
 }
+
+#endif

src/libstore/derivations.cc

@@ -2,6 +2,7 @@
 #include "store-api.hh"
 #include "aterm.hh"
 #include "globals.hh"
+#include "util.hh"
 
 #include "derivations-ast.hh"
 #include "derivations-ast.cc"
@@ -163,9 +164,7 @@ ATerm unparseDerivation(const Derivation & drv)
 
 bool isDerivation(const string & fileName)
 {
-    return
-        fileName.size() >= drvExtension.size() &&
-        string(fileName, fileName.size() - drvExtension.size()) == drvExtension;
+    return hasSuffix(fileName, drvExtension);
 }
 
  

src/libstore/gc.cc

@@ -2,11 +2,12 @@
 #include "misc.hh"
 #include "pathlocks.hh"
 #include "local-store.hh"
-#include "db.hh"
-#include "util.hh"
 
 #include <boost/shared_ptr.hpp>
 
+#include <functional>
+#include <queue>
+
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <errno.h>
@@ -26,6 +27,8 @@ static string gcLockName = "gc.lock";
 static string tempRootsDir = "temproots";
 static string gcRootsDir = "gcroots";
 
+static const int defaultGcLevel = 1000;
+
 
 /* Acquire the global GC lock.  This is used to prevent new Nix
    processes from starting after the temporary root files have been
@@ -123,7 +126,11 @@ Path addPermRoot(const Path & _storePath, const Path & _gcRoot,
         createSymlink(gcRoot, storePath, false);
     }
 
-    /* Check that the root can be found by the garbage collector. */
+    /* Check that the root can be found by the garbage collector.
+       !!! This can be very slow on machines that have many roots.
+       Instead of reading all the roots, it would be more efficient to
+       check if the root is in a directory in or linked from the
+       gcroots directory. */
     if (queryBoolSetting("gc-check-reachability", true)) {
         Roots roots = store->findRoots();
         if (roots.find(gcRoot) == roots.end())
@@ -435,16 +442,149 @@ Paths topoSortPaths(const PathSet & paths)
 }
 
 
-void LocalStore::collectGarbage(GCAction action, const PathSet & pathsToDelete,
-    bool ignoreLiveness, PathSet & result, unsigned long long & bytesFreed)
+static time_t lastFileAccessTime(const Path & path)
 {
-    result.clear();
-    bytesFreed = 0;
+    checkInterrupt();
+    
+    struct stat st;
+    if (lstat(path.c_str(), &st) == -1)
+        throw SysError(format("statting `%1%'") % path);
 
+    if (S_ISDIR(st.st_mode)) {
+        time_t last = 0;
+	Strings names = readDirectory(path);
+	for (Strings::iterator i = names.begin(); i != names.end(); ++i) {
+            time_t t = lastFileAccessTime(path + "/" + *i);
+            if (t > last) last = t;
+        }
+        return last;
+    }
+
+    else if (S_ISLNK(st.st_mode)) return 0;
+
+    else return st.st_atime;
+}
+
+
+struct GCLimitReached { };
+
+
+void LocalStore::gcPath(const GCOptions & options, GCResults & results, 
+    const Path & path)
+{
+    results.paths.insert(path);
+
+    if (!pathExists(path)) return;
+                
+#ifndef __CYGWIN__
+    AutoCloseFD fdLock;
+        
+    /* Only delete a lock file if we can acquire a write lock on it.
+       That means that it's either stale, or the process that created
+       it hasn't locked it yet.  In the latter case the other process
+       will detect that we deleted the lock, and retry (see
+       pathlocks.cc). */
+    if (path.size() >= 5 && string(path, path.size() - 5) == ".lock") {
+        fdLock = openLockFile(path, false);
+        if (fdLock != -1 && !lockFile(fdLock, ltWrite, false)) {
+            debug(format("skipping active lock `%1%'") % path);
+            return;
+        }
+    }
+#endif
+
+    /* Okay, it's safe to delete. */
+    unsigned long long bytesFreed, blocksFreed;
+    deleteFromStore(path, bytesFreed, blocksFreed);
+    results.bytesFreed += bytesFreed;
+    results.blocksFreed += blocksFreed;
+
+    if (results.bytesFreed > options.maxFreed) {
+        printMsg(lvlInfo, format("deleted more than %1% bytes; stopping") % options.maxFreed);
+        throw GCLimitReached();
+    }
+
+    if (options.maxLinks) {
+        struct stat st;
+        if (stat(nixStore.c_str(), &st) == -1)
+            throw SysError(format("statting `%1%'") % nixStore);
+        if (st.st_nlink < options.maxLinks) {
+            printMsg(lvlInfo, format("link count on the store has dropped below %1%; stopping") % options.maxLinks);
+            throw GCLimitReached();
+        }
+    }
+
+#ifndef __CYGWIN__
+    if (fdLock != -1)
+        /* Write token to stale (deleted) lock file. */
+        writeFull(fdLock, (const unsigned char *) "d", 1);
+#endif
+}
+
+
+void LocalStore::gcPathRecursive(const GCOptions & options,
+    GCResults & results, PathSet & done, const Path & path)
+{
+    if (done.find(path) != done.end()) return;
+    done.insert(path);
+
+    startNest(nest, lvlDebug, format("looking at `%1%'") % path);
+        
+    /* Delete all the referrers first.  They must be garbage too,
+       since if they were live, then the current path would also be
+       live.  Note that deleteFromStore() below still makes sure that
+       the referrer set has become empty, just in case.  (However that
+       doesn't guard against deleting top-level paths that are only
+       reachable from GC roots.) */
+    PathSet referrers;
+    if (isValidPath(path))
+        queryReferrers(path, referrers);
+    foreach (PathSet::iterator, i, referrers)
+        if (*i != path) gcPathRecursive(options, results, done, *i);
+
+    printMsg(lvlInfo, format("deleting `%1%'") % path);
+            
+    gcPath(options, results, path);
+}
+
+
+struct CachingAtimeComparator : public std::binary_function<Path, Path, bool> 
+{
+    std::map<Path, time_t> cache;
+
+    time_t lookup(const Path & p)
+    {
+        std::map<Path, time_t>::iterator i = cache.find(p);
+        if (i != cache.end()) return i->second;
+        debug(format("computing atime of `%1%'") % p);
+        cache[p] = lastFileAccessTime(p);
+        assert(cache.find(p) != cache.end());
+        return cache[p];
+    }
+        
+    bool operator () (const Path & p1, const Path & p2)
+    {
+        return lookup(p2) < lookup(p1);
+    }
+};
+
+
+string showTime(const string & format, time_t t)
+{
+    char s[128];
+    strftime(s, sizeof s, format.c_str(), localtime(&t));
+    return string(s);
+}
+
+
+void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
+{
     bool gcKeepOutputs =
         queryBoolSetting("gc-keep-outputs", false);
     bool gcKeepDerivations =
         queryBoolSetting("gc-keep-derivations", true);
+    int gcKeepOutputsThreshold = 
+        queryIntSetting ("gc-keep-outputs-threshold", defaultGcLevel);
 
     /* Acquire the global GC root.  This prevents
        a) New roots from being added.
@@ -453,7 +593,8 @@ void LocalStore::collectGarbage(GCAction action, const PathSet & pathsToDelete,
 
     /* Find the roots.  Since we've grabbed the GC lock, the set of
        permanent roots cannot increase now. */
-    Roots rootMap = ignoreLiveness ? Roots() : nix::findRoots(true);
+    printMsg(lvlError, format("finding garbage collector roots..."));
+    Roots rootMap = options.ignoreLiveness ? Roots() : nix::findRoots(true);
 
     PathSet roots;
     for (Roots::iterator i = rootMap.begin(); i != rootMap.end(); ++i)
@@ -463,16 +604,17 @@ void LocalStore::collectGarbage(GCAction action, const PathSet & pathsToDelete,
        NIX_ROOT_FINDER environment variable.  This is typically used
        to add running programs to the set of roots (to prevent them
        from being garbage collected). */
-    if (!ignoreLiveness)
+    if (!options.ignoreLiveness)
         addAdditionalRoots(roots);
 
-    if (action == gcReturnRoots) {
-        result = roots;
+    if (options.action == GCOptions::gcReturnRoots) {
+        results.paths = roots;
         return;
     }
 
     /* Determine the live paths which is just the closure of the
        roots under the `references' relation. */
+    printMsg(lvlError, format("computing live paths..."));
     PathSet livePaths;
     for (PathSet::const_iterator i = roots.begin(); i != roots.end(); ++i)
         computeFSClosure(canonPath(*i), livePaths);
@@ -484,8 +626,8 @@ void LocalStore::collectGarbage(GCAction action, const PathSet & pathsToDelete,
             /* Note that the deriver need not be valid (e.g., if we
                previously ran the collector with `gcKeepDerivations'
                turned off). */
-            Path deriver = store->queryDeriver(*i);
-            if (deriver != "" && store->isValidPath(deriver))
+            Path deriver = queryDeriver(*i);
+            if (deriver != "" && isValidPath(deriver))
                 computeFSClosure(deriver, livePaths);
         }
     }
@@ -496,15 +638,22 @@ void LocalStore::collectGarbage(GCAction action, const PathSet & pathsToDelete,
              i != livePaths.end(); ++i)
             if (isDerivation(*i)) {
                 Derivation drv = derivationFromPath(*i);
-                for (DerivationOutputs::iterator j = drv.outputs.begin();
-                     j != drv.outputs.end(); ++j)
-                    if (store->isValidPath(j->second.path))
-                        computeFSClosure(j->second.path, livePaths);
+
+		string gcLevelStr = drv.env["__gcLevel"];
+		int gcLevel;
+		if (!string2Int(gcLevelStr, gcLevel))
+		    gcLevel = defaultGcLevel;
+		
+		if (gcLevel >= gcKeepOutputsThreshold)    
+		    for (DerivationOutputs::iterator j = drv.outputs.begin();
+                         j != drv.outputs.end(); ++j)
+			if (isValidPath(j->second.path))
+			    computeFSClosure(j->second.path, livePaths);
             }
     }
 
-    if (action == gcReturnLive) {
-        result = livePaths;
+    if (options.action == GCOptions::gcReturnLive) {
+        results.paths = livePaths;
         return;
     }
 
@@ -523,108 +672,132 @@ void LocalStore::collectGarbage(GCAction action, const PathSet & pathsToDelete,
        means that it has already been closed). */
     PathSet tempRootsClosed;
     for (PathSet::iterator i = tempRoots.begin(); i != tempRoots.end(); ++i)
-        if (store->isValidPath(*i))
+        if (isValidPath(*i))
             computeFSClosure(*i, tempRootsClosed);
         else
             tempRootsClosed.insert(*i);
 
-    /* For testing - see tests/gc-concurrent.sh. */
-    if (getenv("NIX_DEBUG_GC_WAIT"))
-        sleep(2);
-    
     /* After this point the set of roots or temporary roots cannot
        increase, since we hold locks on everything.  So everything
        that is not currently in in `livePaths' or `tempRootsClosed'
        can be deleted. */
     
     /* Read the Nix store directory to find all currently existing
-       paths. */
-    PathSet storePathSet;
-    if (action != gcDeleteSpecific) {
+       paths and filter out all live paths. */
+    printMsg(lvlError, format("reading the Nix store..."));
+    PathSet storePaths;
+    
+    if (options.action != GCOptions::gcDeleteSpecific) {
         Paths entries = readDirectory(nixStore);
-        for (Paths::iterator i = entries.begin(); i != entries.end(); ++i)
-            storePathSet.insert(canonPath(nixStore + "/" + *i));
-    } else {
-        for (PathSet::iterator i = pathsToDelete.begin();
-             i != pathsToDelete.end(); ++i)
-        {
-            assertStorePath(*i);
-            storePathSet.insert(*i);
+        foreach (Paths::iterator, i, entries) {
+            Path path = canonPath(nixStore + "/" + *i);
+            if (livePaths.find(path) == livePaths.end() &&
+                tempRootsClosed.find(path) == tempRootsClosed.end())
+                storePaths.insert(path);
         }
     }
 
-    /* Topologically sort them under the `referrers' relation.  That
-       is, a < b iff a is in referrers(b).  This gives us the order in
-       which things can be deleted safely. */
-    /* !!! when we have multiple output paths per derivation, this
-       will not work anymore because we get cycles. */
-    Paths storePaths = topoSortPaths(storePathSet);
-
-    /* Try to delete store paths in the topologically sorted order. */
-    for (Paths::iterator i = storePaths.begin(); i != storePaths.end(); ++i) {
-
-        debug(format("considering deletion of `%1%'") % *i);
-        
-        if (livePaths.find(*i) != livePaths.end()) {
-            if (action == gcDeleteSpecific)
+    else {
+        foreach (PathSet::iterator, i, options.pathsToDelete) {
+            assertStorePath(*i);
+            storePaths.insert(*i);
+            if (livePaths.find(*i) != livePaths.end())
                 throw Error(format("cannot delete path `%1%' since it is still alive") % *i);
-            debug(format("live path `%1%'") % *i);
-            continue;
+            if (tempRootsClosed.find(*i) != tempRootsClosed.end())
+                throw Error(format("cannot delete path `%1%' since it is temporarily in use") % *i);
+        }
+    }
+
+    if (options.action == GCOptions::gcReturnDead) {
+        results.paths.insert(storePaths.begin(), storePaths.end());
+        return;
+    }
+
+    /* Delete all dead store paths (or until one of the stop
+       conditions is reached). */
+
+    PathSet done;
+    try {
+
+        if (!options.useAtime) {
+            /* Delete the paths, respecting the partial ordering
+               determined by the references graph. */
+            printMsg(lvlError, format("deleting garbage..."));
+            foreach (PathSet::iterator, i, storePaths)
+                gcPathRecursive(options, results, done, *i);
         }
 
-        if (tempRootsClosed.find(*i) != tempRootsClosed.end()) {
-            debug(format("temporary root `%1%'") % *i);
-            continue;
-        }
+        else {
 
-        debug(format("dead path `%1%'") % *i);
-        result.insert(*i);
+            /* Delete in order of ascending last access time, still
+               maintaining the partial ordering of the reference
+               graph.  Note that we can't use a topological sort for
+               this because that takes time O(V+E), and in this case
+               E=O(V^2) (i.e. the graph is dense because of the edges
+               due to the atime ordering).  So instead we put all
+               deletable paths in a priority queue (ordered by atime),
+               and after deleting a path, add additional paths that
+               have become deletable to the priority queue. */
 
-        /* If just returning the set of dead paths, we also return the
-           space that would be freed if we deleted them. */
-        if (action == gcReturnDead)
-            bytesFreed += computePathSize(*i);
+            CachingAtimeComparator atimeComp;
 
-        if (action == gcDeleteDead || action == gcDeleteSpecific) {
+            /* Create a priority queue that orders paths by ascending
+               atime.  This is why C++ needs type inferencing... */
+            std::priority_queue<Path, vector<Path>, binary_function_ref_adapter<CachingAtimeComparator> > prioQueue =
+                std::priority_queue<Path, vector<Path>, binary_function_ref_adapter<CachingAtimeComparator> >(binary_function_ref_adapter<CachingAtimeComparator>(&atimeComp));
 
-#ifndef __CYGWIN__
-            AutoCloseFD fdLock;
+           /* Initially put the paths that are invalid or have no
+              referrers into the priority queue. */
+            printMsg(lvlError, format("finding deletable paths..."));
+            foreach (PathSet::iterator, i, storePaths) {
+                checkInterrupt();
+                /* We can safely delete a path if it's invalid or
+                   it has no referrers.  Note that all the invalid
+                   paths will be deleted in the first round. */
+                if (isValidPath(*i)) {
+                    if (queryReferrersNoSelf(*i).empty()) prioQueue.push(*i);
+                } else prioQueue.push(*i);
+            }
 
-            /* Only delete a lock file if we can acquire a write lock
-               on it.  That means that it's either stale, or the
-               process that created it hasn't locked it yet.  In the
-               latter case the other process will detect that we
-               deleted the lock, and retry (see pathlocks.cc). */
-            if (i->size() >= 5 && string(*i, i->size() - 5) == ".lock") {
-                fdLock = openLockFile(*i, false);
-                if (fdLock != -1 && !lockFile(fdLock, ltWrite, false)) {
-                    debug(format("skipping active lock `%1%'") % *i);
+            debug(format("%1% initially deletable paths") % prioQueue.size());
+
+            /* Now delete everything in the order of the priority
+               queue until nothing is left. */
+            printMsg(lvlError, format("deleting garbage..."));
+            while (!prioQueue.empty()) {
+                checkInterrupt();
+                Path path = prioQueue.top(); prioQueue.pop();
+
+                if (options.maxAtime != (time_t) -1 &&
+                    atimeComp.lookup(path) > options.maxAtime)
                     continue;
+                
+                printMsg(lvlInfo, format("deleting `%1%' (last accessed %2%)") % path % showTime("%F %H:%M:%S", atimeComp.lookup(path)));
+
+                PathSet references;
+                if (isValidPath(path)) references = queryReferencesNoSelf(path);
+
+                gcPath(options, results, path);
+
+                /* For each reference of the current path, see if the
+                   reference has now become deletable (i.e. is in the
+                   set of dead paths and has no referrers left).  If
+                   so add it to the priority queue. */
+                foreach (PathSet::iterator, i, references) {
+                    if (storePaths.find(*i) != storePaths.end() &&
+                        queryReferrersNoSelf(*i).empty())
+                    {
+                        debug(format("path `%1%' has become deletable") % *i);
+                        prioQueue.push(*i);
+                    }
                 }
             }
-#endif
-
-            if (!pathExists(*i)) continue;
-                
-            printMsg(lvlInfo, format("deleting `%1%'") % *i);
             
-            /* Okay, it's safe to delete. */
-            try {
-                unsigned long long freed;
-                deleteFromStore(*i, freed);
-                bytesFreed += freed;
-            } catch (PathInUse & e) {
-                printMsg(lvlError, format("warning: %1%") % e.msg());
-            }
-
-#ifndef __CYGWIN__
-            if (fdLock != -1)
-                /* Write token to stale (deleted) lock file. */
-                writeFull(fdLock, (const unsigned char *) "d", 1);
-#endif
         }
+        
+    } catch (GCLimitReached & e) {
     }
 }
 
- 
+
 }

src/libstore/globals.cc

@@ -16,6 +16,7 @@ string nixDBPath = "/UNINIT";
 string nixConfDir = "/UNINIT";
 string nixLibexecDir = "/UNINIT";
 string nixBinDir = "/UNINIT";
+string nixChrootsDir = "/UNINIT";
 
 bool keepFailed = false;
 bool keepGoing = false;
@@ -26,6 +27,8 @@ bool readOnlyMode = false;
 string thisSystem = "unset";
 unsigned int maxSilentTime = 0;
 Paths substituters;
+bool useBuildHook = true;
+bool printBuildTrace = false;
 
 
 static bool settingsRead = false;
@@ -115,5 +118,12 @@ unsigned int queryIntSetting(const string & name, unsigned int def)
     return n;
 }
 
+
+void reloadSettings()
+{
+    settingsRead = false;
+    settings.clear();
+}
+
  
 }

src/libstore/globals.hh

@@ -35,6 +35,12 @@ extern string nixLibexecDir;
 /* nixBinDir is the directory where the main programs are stored. */
 extern string nixBinDir;
 
+/* nixChrootsDir is the directory where we create chroot environments
+   (when chroot builds are enabled).  We don't put these under /tmp to
+   prevent "rm -rf /tmp" from recursing into /nix/store via the bind
+   mounts in the chroots. */
+extern string nixChrootsDir;
+
 
 /* Misc. global flags. */
 
@@ -72,6 +78,26 @@ extern unsigned int maxSilentTime;
    from a CD. */
 extern Paths substituters;
 
+/* Whether to use build hooks (for distributed builds).  Sometimes
+   users want to disable this from the command-line. */
+extern bool useBuildHook;
+
+/* Whether buildDerivations() should print out lines on stderr in a
+   fixed format to allow its progress to be monitored.  Each line
+   starts with a "@".  The following are defined:
+
+   @ build-started <drvpath> <outpath> <system> <logfile>
+   @ build-failed <drvpath> <outpath> <exitcode> <error text>
+   @ build-succeeded <drvpath> <outpath>
+   @ substituter-started <outpath> <substituter>
+   @ substituter-failed <outpath> <exitcode> <error text>
+   @ substituter-succeeded <outpath>
+
+   Best combined with --no-build-output, otherwise stderr might
+   conceivably contain lines in this format printed by the builders.
+*/
+extern bool printBuildTrace;
+
 
 Strings querySetting(const string & name, const Strings & def);
 
@@ -81,6 +107,8 @@ bool queryBoolSetting(const string & name, bool def);
 
 unsigned int queryIntSetting(const string & name, unsigned int def);
 
+void reloadSettings();
+
     
 }
 

src/libstore/local-store.hh

@@ -3,19 +3,19 @@
 
 #include <string>
 
+#include <ext/stdio_filebuf.h>
+
 #include "store-api.hh"
+#include "util.hh"
 
 
 namespace nix {
 
 
-class Transaction;
-
-
 /* Nix store and database schema version.  Version 1 (or 0) was Nix <=
    0.7.  Version 2 was Nix 0.8 and 0.9.  Version 3 is Nix 0.10.
-   Version 4 is Nix 0.11. */
-const int nixSchemaVersion = 4;
+   Version 4 is Nix 0.11.  Version 5 is Nix 0.12*/
+const int nixSchemaVersion = 5;
 
 
 extern string drvsLogDir;
@@ -27,31 +27,41 @@ struct OptimiseStats
     unsigned long sameContents;
     unsigned long filesLinked;
     unsigned long long bytesFreed;
+    unsigned long long blocksFreed;
     OptimiseStats()
     {
         totalFiles = sameContents = filesLinked = 0;
-        bytesFreed = 0;
+        bytesFreed = blocksFreed = 0;
     }
 };
 
 
+typedef __gnu_cxx::stdio_filebuf<char> stdio_filebuf;
+
+
+struct RunningSubstituter
+{
+    Pid pid;
+    boost::shared_ptr<stdio_filebuf> toBuf, fromBuf;
+    boost::shared_ptr<std::ostream> to;
+    boost::shared_ptr<std::istream> from;
+};
+
+
 class LocalStore : public StoreAPI
 {
 private:
     bool substitutablePathsLoaded;
     PathSet substitutablePaths;
+
+    typedef std::map<Path, RunningSubstituter> RunningSubstituters;
+    RunningSubstituters runningSubstituters;
     
 public:
 
-    /* Open the database environment.  If `reserveSpace' is true, make
-       sure that a big empty file exists in /nix/var/nix/db/reserved.
-       If `reserveSpace' is false, delete this file if it exists.  The
-       idea is that on normal operation, the file exists; but when we
-       run the garbage collector, it is deleted.  This is to ensure
-       that the garbage collector has a small amount of disk space
-       available, which is required to open the Berkeley DB
-       environment. */
-    LocalStore(bool reserveSpace);
+    /* Initialise the local store, upgrading the schema if
+       necessary. */
+    LocalStore();
 
     ~LocalStore();
     
@@ -59,6 +69,8 @@ public:
     
     bool isValidPath(const Path & path);
 
+    PathSet queryValidPaths();
+    
     Hash queryPathHash(const Path & path);
 
     void queryReferences(const Path & path, PathSet & references);
@@ -70,6 +82,12 @@ public:
     PathSet querySubstitutablePaths();
     
     bool hasSubstitutes(const Path & path);
+
+    bool querySubstitutablePathInfo(const Path & path,
+        SubstitutablePathInfo & info);
+    
+    bool querySubstitutablePathInfo(const Path & substituter,
+        const Path & path, SubstitutablePathInfo & info);
     
     Path addToStore(const Path & srcPath, bool fixed = false,
         bool recursive = false, string hashAlgo = "",
@@ -95,36 +113,74 @@ public:
 
     Roots findRoots();
 
-    void collectGarbage(GCAction action, const PathSet & pathsToDelete,
-        bool ignoreLiveness, PathSet & result, unsigned long long & bytesFreed);
+    void collectGarbage(const GCOptions & options, GCResults & results);
 
+    /* Delete a path from the Nix store. */
+    void deleteFromStore(const Path & path, unsigned long long & bytesFreed,
+        unsigned long long & blocksFreed);
+    
     /* Optimise the disk space usage of the Nix store by hard-linking
        files with the same contents. */
     void optimiseStore(bool dryRun, OptimiseStats & stats);
+
+    /* Check the integrity of the Nix store. */
+    void verifyStore(bool checkContents);
+
+    /* Register the validity of a path, i.e., that `path' exists, that
+       the paths referenced by it exists, and in the case of an output
+       path of a derivation, that it has been produced by a succesful
+       execution of the derivation (or something equivalent).  Also
+       register the hash of the file system contents of the path.  The
+       hash must be a SHA-256 hash. */
+    void registerValidPath(const Path & path,
+        const Hash & hash, const PathSet & references, const Path & deriver);
+
+    void registerValidPaths(const ValidPathInfos & infos);
+
+private:
+
+    Path schemaPath;
+
+    /* Lock file used for upgrading. */
+    AutoCloseFD globalLock;
+
+    /* !!! The cache can grow very big.  Maybe it should be pruned
+       every once in a while. */
+    std::map<Path, ValidPathInfo> pathInfoCache;
+
+    /* Store paths for which the referrers file must be purged. */
+    PathSet delayedUpdates;
+
+    int getSchema();
+
+    void registerValidPath(const ValidPathInfo & info, bool ignoreValidity = false);
+
+    ValidPathInfo queryPathInfo(const Path & path);
+
+    void rewriteReferrers(const Path & path, bool purge, PathSet referrers);
+
+    void flushDelayedUpdates();
+    
+    bool queryReferrersInternal(const Path & path, PathSet & referrers);
+    
+    void invalidatePath(const Path & path);
+    
+    void upgradeStore12();
+
+    void gcPath(const GCOptions & options, GCResults & results,
+        const Path & path);
+
+    void gcPathRecursive(const GCOptions & options,
+        GCResults & results, PathSet & done, const Path & path);
+
+    void startSubstituter(const Path & substituter,
+        RunningSubstituter & runningSubstituter);
 };
 
 
-/* Get a transaction object. */
-void createStoreTransaction(Transaction & txn);
-
 /* Copy a path recursively. */
 void copyPath(const Path & src, const Path & dst);
 
-/* Register the validity of a path, i.e., that `path' exists, that the
-   paths referenced by it exists, and in the case of an output path of
-   a derivation, that it has been produced by a succesful execution of
-   the derivation (or something equivalent).  Also register the hash
-   of the file system contents of the path.  The hash must be a
-   SHA-256 hash. */
-void registerValidPath(const Transaction & txn,
-    const Path & path, const Hash & hash, const PathSet & references,
-    const Path & deriver);
-
-typedef list<ValidPathInfo> ValidPathInfos;
-
-void registerValidPaths(const Transaction & txn,
-    const ValidPathInfos & infos);
-
 /* "Fix", or canonicalise, the meta-data of the files in a store path
    after it has been built.  In particular:
    - the last modification date on each file is set to 0 (i.e.,
@@ -135,25 +191,10 @@ void registerValidPaths(const Transaction & txn,
      in a setuid Nix installation. */
 void canonicalisePathMetaData(const Path & path);
 
-/* Checks whether a path is valid. */ 
-bool isValidPathTxn(const Transaction & txn, const Path & path);
-
-/* Sets the set of outgoing FS references for a store path.  Use with
-   care! */
-void setReferences(const Transaction & txn, const Path & path,
-    const PathSet & references);
-
-/* Sets the deriver of a store path.  Use with care! */
-void setDeriver(const Transaction & txn, const Path & path,
-    const Path & deriver);
-
-/* Delete a value from the nixStore directory. */
-void deleteFromStore(const Path & path, unsigned long long & bytesFreed);
+void canonicalisePathMetaData(const Path & path, bool recurse);
 
 MakeError(PathInUse, Error);
 
-void verifyStore(bool checkContents);
-
 /* Whether we are in build users mode. */
 bool haveBuildUsers();
 
@@ -166,7 +207,7 @@ void getOwnership(const Path & path);
 /* Like deletePath(), but changes the ownership of `path' using the
    setuid wrapper if necessary (and possible). */
 void deletePathWrapped(const Path & path,
-    unsigned long long & bytesFreed);
+    unsigned long long & bytesFreed, unsigned long long & blocksFreed);
 
 void deletePathWrapped(const Path & path);
  

src/libstore/misc.cc

@@ -1,6 +1,6 @@
 #include "misc.hh"
 #include "store-api.hh"
-#include "db.hh"
+#include "local-store.hh"
 
 #include <aterm2.h>
 
@@ -46,8 +46,11 @@ Path findOutput(const Derivation & drv, string id)
 
 
 void queryMissing(const PathSet & targets,
-    PathSet & willBuild, PathSet & willSubstitute)
+    PathSet & willBuild, PathSet & willSubstitute, PathSet & unknown,
+    unsigned long long & downloadSize)
 {
+    downloadSize = 0;
+    
     PathSet todo(targets.begin(), targets.end()), done;
 
     while (!todo.empty()) {
@@ -57,7 +60,10 @@ void queryMissing(const PathSet & targets,
         done.insert(p);
 
         if (isDerivation(p)) {
-            if (!store->isValidPath(p)) continue;
+            if (!store->isValidPath(p)) {
+                unknown.insert(p);
+                continue;
+            }
             Derivation drv = derivationFromPath(p);
 
             bool mustBuild = false;
@@ -80,10 +86,13 @@ void queryMissing(const PathSet & targets,
 
         else {
             if (store->isValidPath(p)) continue;
-            if (store->hasSubstitutes(p))
+            SubstitutablePathInfo info;
+            if (store->querySubstitutablePathInfo(p, info)) {
                 willSubstitute.insert(p);
-            // XXX call the substituters
-            // store->queryReferences(p, todo);
+                downloadSize += info.downloadSize;
+                todo.insert(info.references.begin(), info.references.end());
+            } else
+                unknown.insert(p);
         }
     }
 }

src/libstore/misc.hh

@@ -29,7 +29,8 @@ Path findOutput(const Derivation & drv, string id);
    derivations that will be built, and the set of output paths that
    will be substituted. */
 void queryMissing(const PathSet & targets,
-    PathSet & willBuild, PathSet & willSubstitute);
+    PathSet & willBuild, PathSet & willSubstitute, PathSet & unknown,
+    unsigned long long & downloadSize);
 
 
 }

src/libstore/optimise-store.cc

@@ -0,0 +1,155 @@
+#include "util.hh"
+#include "local-store.hh"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <errno.h>
+
+
+namespace nix {
+
+
+typedef std::map<Hash, std::pair<Path, ino_t> > HashToPath;
+
+
+static void makeWritable(const Path & path)
+{
+    struct stat st;
+    if (lstat(path.c_str(), &st))
+	throw SysError(format("getting attributes of path `%1%'") % path);
+    if (chmod(path.c_str(), st.st_mode | S_IWUSR) == -1)
+        throw SysError(format("changing writability of `%1%'") % path);
+}
+
+
+struct MakeReadOnly
+{
+    Path path;
+    MakeReadOnly(const Path & path) : path(path) { }
+    ~MakeReadOnly()
+    {
+        try {
+            if (path != "") canonicalisePathMetaData(path, false);
+        } catch (...) {
+            ignoreException();
+        }
+    }
+};
+
+
+static void hashAndLink(bool dryRun, HashToPath & hashToPath,
+    OptimiseStats & stats, const Path & path)
+{
+    struct stat st;
+    if (lstat(path.c_str(), &st))
+	throw SysError(format("getting attributes of path `%1%'") % path);
+
+    /* Sometimes SNAFUs can cause files in the Nix store to be
+       modified, in particular when running programs as root under
+       NixOS (example: $fontconfig/var/cache being modified).  Skip
+       those files. */
+    if (S_ISREG(st.st_mode) && (st.st_mode & S_IWUSR)) {
+        printMsg(lvlError, format("skipping suspicious writable file `%1%'") % path);
+        return;
+    }
+
+    /* We can hard link regular files and symlinks. */
+    if (S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)) {
+
+        /* Hash the file.  Note that hashPath() returns the hash over
+           the NAR serialisation, which includes the execute bit on
+           the file.  Thus, executable and non-executable files with
+           the same contents *won't* be linked (which is good because
+           otherwise the permissions would be screwed up).
+
+           Also note that if `path' is a symlink, then we're hashing
+           the contents of the symlink (i.e. the result of
+           readlink()), not the contents of the target (which may not
+           even exist). */
+        Hash hash = hashPath(htSHA256, path);
+        stats.totalFiles++;
+        printMsg(lvlDebug, format("`%1%' has hash `%2%'") % path % printHash(hash));
+
+        std::pair<Path, ino_t> prevPath = hashToPath[hash];
+        
+        if (prevPath.first == "") {
+            hashToPath[hash] = std::pair<Path, ino_t>(path, st.st_ino);
+            return;
+        }
+            
+        /* Yes!  We've seen a file with the same contents.  Replace
+           the current file with a hard link to that file. */
+        stats.sameContents++;
+        if (prevPath.second == st.st_ino) {
+            printMsg(lvlDebug, format("`%1%' is already linked to `%2%'") % path % prevPath.first);
+            return;
+        }
+        
+        if (!dryRun) {
+            
+            printMsg(lvlTalkative, format("linking `%1%' to `%2%'") % path % prevPath.first);
+
+            Path tempLink = (format("%1%.tmp-%2%-%3%")
+                % path % getpid() % rand()).str();
+
+            /* Make the containing directory writable, but only if
+               it's not the store itself (we don't want or need to
+               mess with  its permissions). */
+            bool mustToggle = !isStorePath(path);
+            if (mustToggle) makeWritable(dirOf(path));
+            
+            /* When we're done, make the directory read-only again and
+               reset its timestamp back to 0. */
+            MakeReadOnly makeReadOnly(mustToggle ? dirOf(path) : "");
+        
+            if (link(prevPath.first.c_str(), tempLink.c_str()) == -1) {
+                if (errno == EMLINK) {
+                    /* Too many links to the same file (>= 32000 on
+                       most file systems).  This is likely to happen
+                       with empty files.  Just start over, creating
+                       links to the current file. */
+                    printMsg(lvlInfo, format("`%1%' has maximum number of links") % prevPath.first);
+                    hashToPath[hash] = std::pair<Path, ino_t>(path, st.st_ino);
+                    return;
+                }
+                throw SysError(format("cannot link `%1%' to `%2%'")
+                    % tempLink % prevPath.first);
+            }
+
+            /* Atomically replace the old file with the new hard link. */
+            if (rename(tempLink.c_str(), path.c_str()) == -1)
+                throw SysError(format("cannot rename `%1%' to `%2%'")
+                    % tempLink % path);
+        } else
+            printMsg(lvlTalkative, format("would link `%1%' to `%2%'") % path % prevPath.first);
+        
+        stats.filesLinked++;
+        stats.bytesFreed += st.st_size;
+        stats.blocksFreed += st.st_blocks;
+    }
+
+    if (S_ISDIR(st.st_mode)) {
+        Strings names = readDirectory(path);
+	for (Strings::iterator i = names.begin(); i != names.end(); ++i)
+	    hashAndLink(dryRun, hashToPath, stats, path + "/" + *i);
+    }
+}
+
+
+void LocalStore::optimiseStore(bool dryRun, OptimiseStats & stats)
+{
+    HashToPath hashToPath;
+
+    PathSet paths = queryValidPaths();
+
+    for (PathSet::iterator i = paths.begin(); i != paths.end(); ++i) {
+        addTempRoot(*i);
+        if (!isValidPath(*i)) continue; /* path was GC'ed, probably */
+        startNest(nest, lvlChatty, format("hashing files in `%1%'") % *i);
+        hashAndLink(dryRun, hashToPath, stats, *i);
+    }
+}
+
+
+}

src/libstore/pathlocks.cc

@@ -2,6 +2,7 @@
 #include "util.hh"
 
 #include <cerrno>
+#include <cstdlib>
 
 #include <sys/types.h>
 #include <sys/stat.h>

src/libstore/pathlocks.hh

@@ -17,7 +17,7 @@ int openLockFile(const Path & path, bool create);
 void deleteLockFilePreClose(const Path & path, int fd);
 void deleteLockFilePostClose(const Path & path);
 
-typedef enum LockType { ltRead, ltWrite, ltNone };
+enum LockType { ltRead, ltWrite, ltNone };
 
 bool lockFile(int fd, LockType lockType, bool wait);
 

src/libstore/references.cc

@@ -3,6 +3,8 @@
 #include "util.hh"
 
 #include <cerrno>
+#include <cstring>
+#include <cstdlib>
 #include <map>
 
 #include <sys/types.h>

src/libstore/remote-store.cc

@@ -59,7 +59,7 @@ RemoteStore::RemoteStore()
         unsigned int magic = readInt(from);
         if (magic != WORKER_MAGIC_2) throw Error("protocol mismatch");
 
-        unsigned int daemonVersion = readInt(from);
+        daemonVersion = readInt(from);
         if (GET_PROTOCOL_MAJOR(daemonVersion) != GET_PROTOCOL_MAJOR(PROTOCOL_VERSION))
             throw Error("Nix daemon protocol version not supported");
         writeInt(PROTOCOL_VERSION, to);
@@ -137,14 +137,26 @@ void RemoteStore::connectToDaemon()
 
     string socketPath = nixStateDir + DEFAULT_SOCKET_PATH;
 
+    /* Urgh, sockaddr_un allows path names of only 108 characters.  So
+       chdir to the socket directory so that we can pass a relative
+       path name.  !!! this is probably a bad idea in multi-threaded
+       applications... */
+    AutoCloseFD fdPrevDir = open(".", O_RDONLY);
+    if (fdPrevDir == -1) throw SysError("couldn't open current directory");
+    chdir(dirOf(socketPath).c_str()); 
+    Path socketPathRel = "./" + baseNameOf(socketPath);
+    
     struct sockaddr_un addr;
     addr.sun_family = AF_UNIX;
-    if (socketPath.size() >= sizeof(addr.sun_path))
-        throw Error(format("socket path `%1%' is too long") % socketPath);
-    strcpy(addr.sun_path, socketPath.c_str());
+    if (socketPathRel.size() >= sizeof(addr.sun_path))
+        throw Error(format("socket path `%1%' is too long") % socketPathRel);
+    strcpy(addr.sun_path, socketPathRel.c_str());
     
     if (connect(fdSocket, (struct sockaddr *) &addr, sizeof(addr)) == -1)
         throw SysError(format("cannot connect to daemon at `%1%'") % socketPath);
+
+    if (fchdir(fdPrevDir) == -1)
+        throw SysError("couldn't change back to previous directory");
 }
 
 
@@ -169,6 +181,13 @@ void RemoteStore::setOptions()
     writeInt(verbosity, to);
     writeInt(maxBuildJobs, to);
     writeInt(maxSilentTime, to);
+    if (GET_PROTOCOL_MINOR(daemonVersion) >= 2)
+        writeInt(useBuildHook, to);
+    if (GET_PROTOCOL_MINOR(daemonVersion) >= 4) {
+        writeInt(buildVerbosity, to);
+        writeInt(logType, to);
+        writeInt(printBuildTrace, to);
+    }
     processStderr();
 }
 
@@ -183,6 +202,12 @@ bool RemoteStore::isValidPath(const Path & path)
 }
 
 
+PathSet RemoteStore::queryValidPaths()
+{
+    throw Error("not implemented");
+}
+
+
 bool RemoteStore::hasSubstitutes(const Path & path)
 {
     writeInt(wopHasSubstitutes, to);
@@ -193,6 +218,23 @@ bool RemoteStore::hasSubstitutes(const Path & path)
 }
 
 
+bool RemoteStore::querySubstitutablePathInfo(const Path & path,
+    SubstitutablePathInfo & info)
+{
+    if (GET_PROTOCOL_MINOR(daemonVersion) < 3) return false;
+    writeInt(wopQuerySubstitutablePathInfo, to);
+    writeString(path, to);
+    processStderr();
+    unsigned int reply = readInt(from);
+    if (reply == 0) return false;
+    info.deriver = readString(from);
+    if (info.deriver != "") assertStorePath(info.deriver);
+    info.references = readStorePaths(from);
+    info.downloadSize = readLongLong(from);
+    return true;
+}
+
+
 Hash RemoteStore::queryPathHash(const Path & path)
 {
     writeInt(wopQueryPathHash, to);
@@ -230,13 +272,9 @@ Path RemoteStore::queryDeriver(const Path & path)
     writeInt(wopQueryDeriver, to);
     writeString(path, to);
     processStderr();
-    return readStorePath(from);
-}
-
-
-PathSet RemoteStore::querySubstitutablePaths()
-{
-    throw Error("not implemented");
+    Path drvPath = readString(from);
+    if (drvPath != "") assertStorePath(drvPath);
+    return drvPath;
 }
 
 
@@ -350,24 +388,20 @@ Roots RemoteStore::findRoots()
 }
 
 
-void RemoteStore::collectGarbage(GCAction action, const PathSet & pathsToDelete,
-    bool ignoreLiveness, PathSet & result, unsigned long long & bytesFreed)
+void RemoteStore::collectGarbage(const GCOptions & options, GCResults & results)
 {
-    result.clear();
-    bytesFreed = 0;
     writeInt(wopCollectGarbage, to);
-    writeInt(action, to);
-    writeStringSet(pathsToDelete, to);
-    writeInt(ignoreLiveness, to);
+    writeInt(options.action, to);
+    writeStringSet(options.pathsToDelete, to);
+    writeInt(options.ignoreLiveness, to);
+    writeLongLong(options.maxFreed, to);
+    writeInt(options.maxLinks, to);
     
     processStderr();
     
-    result = readStringSet(from);
-
-    /* Ugh - NAR integers are 64 bits, but read/writeInt() aren't. */
-    unsigned int lo = readInt(from);
-    unsigned int hi = readInt(from);
-    bytesFreed = (((unsigned long long) hi) << 32) | lo;
+    results.paths = readStringSet(from);
+    results.bytesFreed = readLongLong(from);
+    results.blocksFreed = readLongLong(from);
 }
 
 

src/libstore/remote-store.hh

@@ -27,6 +27,8 @@ public:
     
     bool isValidPath(const Path & path);
 
+    PathSet queryValidPaths();
+    
     Hash queryPathHash(const Path & path);
 
     void queryReferences(const Path & path, PathSet & references);
@@ -35,10 +37,11 @@ public:
 
     Path queryDeriver(const Path & path);
     
-    PathSet querySubstitutablePaths();
-    
     bool hasSubstitutes(const Path & path);
     
+    bool querySubstitutablePathInfo(const Path & path,
+        SubstitutablePathInfo & info);
+    
     Path addToStore(const Path & srcPath, bool fixed = false,
         bool recursive = false, string hashAlgo = "",
         PathFilter & filter = defaultPathFilter);
@@ -63,14 +66,14 @@ public:
     
     Roots findRoots();
 
-    void collectGarbage(GCAction action, const PathSet & pathsToDelete,
-        bool ignoreLiveness, PathSet & result, unsigned long long & bytesFreed);
+    void collectGarbage(const GCOptions & options, GCResults & results);
     
 private:
     AutoCloseFD fdSocket;
     FdSink to;
     FdSource from;
     Pid child;
+    unsigned int daemonVersion;
 
     void processStderr(Sink * sink = 0, Source * source = 0);
 

src/libstore/store-api.cc

@@ -2,14 +2,26 @@
 #include "globals.hh"
 #include "util.hh"
 
+#include <limits.h>
+
+
+/* Needed for some ancient environments. */
+#ifndef ULLONG_MAX
+#define ULLONG_MAX 18446744073709551615
+#endif
+
 
 namespace nix {
 
 
-bool StoreAPI::hasSubstitutes(const Path & path)
+GCOptions::GCOptions()
 {
-    PathSet paths = querySubstitutablePaths();
-    return paths.find(path) != paths.end();
+    action = gcDeleteDead;
+    ignoreLiveness = false;
+    maxFreed = ULLONG_MAX;
+    maxLinks = 0;
+    useAtime = false;
+    maxAtime = (time_t) -1;
 }
 
 
@@ -48,6 +60,26 @@ Path toStorePath(const Path & path)
 }
 
 
+Path followLinksToStore(const Path & _path)
+{
+    Path path = absPath(_path);
+    while (!isInStore(path)) {
+        if (!isLink(path)) break;
+        string target = readLink(path);
+        path = absPath(target, dirOf(path));
+    }
+    if (!isInStore(path))
+        throw Error(format("path `%1%' is not in the Nix store") % path);
+    return path;
+}
+
+
+Path followLinksToStorePath(const Path & path)
+{
+    return toStorePath(followLinksToStore(path));
+}
+
+
 void checkStoreName(const string & name)
 {
     string validChars = "+-._?=";
@@ -131,11 +163,47 @@ Path computeStorePathForText(const string & suffix, const string & s,
 }
 
 
-ValidPathInfo decodeValidPathInfo(std::istream & str)
+/* Return a string accepted by decodeValidPathInfo() that
+   registers the specified paths as valid.  Note: it's the
+   responsibility of the caller to provide a closure. */
+string makeValidityRegistration(const PathSet & paths,
+    bool showDerivers, bool showHash)
+{
+    string s = "";
+    
+    for (PathSet::iterator i = paths.begin(); i != paths.end(); ++i) {
+        s += *i + "\n";
+
+        if (showHash)
+            s += printHash(store->queryPathHash(*i)) + "\n";
+
+        Path deriver = showDerivers ? store->queryDeriver(*i) : "";
+        s += deriver + "\n";
+
+        PathSet references;
+        store->queryReferences(*i, references);
+
+        s += (format("%1%\n") % references.size()).str();
+            
+        for (PathSet::iterator j = references.begin();
+             j != references.end(); ++j)
+            s += *j + "\n";
+    }
+
+    return s;
+}
+
+
+ValidPathInfo decodeValidPathInfo(std::istream & str, bool hashGiven)
 {
     ValidPathInfo info;
     getline(str, info.path);
     if (str.eof()) { info.path = ""; return info; }
+    if (hashGiven) {
+        string s;
+        getline(str, s);
+        info.hash = parseHash(htSHA256, s);
+    }
     getline(str, info.deriver);
     string s; int n;
     getline(str, s);
@@ -149,6 +217,19 @@ ValidPathInfo decodeValidPathInfo(std::istream & str)
 }
 
 
+string showPaths(const PathSet & paths)
+{
+    string s;
+    for (PathSet::const_iterator i = paths.begin();
+         i != paths.end(); ++i)
+    {
+        if (s.size() != 0) s += ", ";
+        s += "`" + *i + "'";
+    }
+    return s;
+}
+
+
 }
 
 
@@ -163,10 +244,10 @@ namespace nix {
 boost::shared_ptr<StoreAPI> store;
 
 
-boost::shared_ptr<StoreAPI> openStore(bool reserveSpace)
+boost::shared_ptr<StoreAPI> openStore()
 {
     if (getEnv("NIX_REMOTE") == "")
-        return boost::shared_ptr<StoreAPI>(new LocalStore(reserveSpace));
+        return boost::shared_ptr<StoreAPI>(new LocalStore());
     else
         return boost::shared_ptr<StoreAPI>(new RemoteStore());
 }

src/libstore/store-api.hh

@@ -16,14 +16,100 @@ namespace nix {
 typedef std::map<Path, Path> Roots;
 
 
-/* Garbage collector operation. */
-typedef enum {
-    gcReturnRoots,
-    gcReturnLive,
-    gcReturnDead,
-    gcDeleteDead,
-    gcDeleteSpecific,
-} GCAction;
+
+
+struct GCOptions
+{
+    /* Garbage collector operation:
+
+       - `gcReturnRoots': find and return the set of roots for the
+         garbage collector.  These are the store paths symlinked to in
+         the `gcroots' directory.
+
+       - `gcReturnLive': return the set of paths reachable from
+         (i.e. in the closure of) the roots.
+
+       - `gcReturnDead': return the set of paths not reachable from
+         the roots.
+
+       - `gcDeleteDead': actually delete the latter set.
+
+       - `gcDeleteSpecific': delete the paths listed in
+          `pathsToDelete', insofar as they are not reachable.
+    */
+    typedef enum {
+        gcReturnRoots,
+        gcReturnLive,
+        gcReturnDead,
+        gcDeleteDead,
+        gcDeleteSpecific,
+    } GCAction;
+
+    GCAction action;
+
+    /* If `ignoreLiveness' is set, then reachability from the roots is
+       ignored (dangerous!).  However, the paths must still be
+       unreferenced *within* the store (i.e., there can be no other
+       store paths that depend on them). */
+    bool ignoreLiveness;
+
+    /* For `gcDeleteSpecific', the paths to delete. */
+    PathSet pathsToDelete;
+
+    /* Stop after at least `maxFreed' bytes have been freed. */
+    unsigned long long maxFreed;
+
+    /* Stop after the number of hard links to the Nix store directory
+       has dropped below `maxLinks'. */
+    unsigned int maxLinks;
+
+    /* Delete paths in order of ascending last access time.  I.e.,
+       prefer deleting unrecently used paths.  Useful in conjunction
+       with `maxFreed' and `maxLinks' (or manual interruption).  The
+       access time of a path is defined as the highest atime of any
+       non-directory, non-symlink file under that path.  Directories
+       and symlinks are ignored because their atimes are frequently
+       mass-updated, e.g. by `locate'.  Note that optimiseStore()
+       somewhat reduces the usefulness of this option: it hard-links
+       regular files and symlink together, giving them a "shared"
+       atime. */
+    bool useAtime;
+
+    /* Do not delete paths newer than `maxAtime'.  -1 means no age
+       limit. */
+    time_t maxAtime;
+
+    GCOptions();
+};
+
+
+struct GCResults 
+{
+    /* Depending on the action, the GC roots, or the paths that would
+       be or have been deleted. */
+    PathSet paths;
+
+    /* For `gcReturnDead', `gcDeleteDead' and `gcDeleteSpecific', the
+       number of bytes that would be or was freed. */
+    unsigned long long bytesFreed;
+
+    /* The number of file system blocks that would be or was freed. */
+    unsigned long long blocksFreed;
+
+    GCResults()
+    {
+        bytesFreed = 0;
+        blocksFreed = 0;
+    }
+};
+
+
+struct SubstitutablePathInfo
+{
+    Path deriver;
+    PathSet references;
+    unsigned long long downloadSize; /* 0 = unknown or inapplicable */
+};
 
 
 class StoreAPI 
@@ -35,6 +121,9 @@ public:
     /* Checks whether a path is valid. */ 
     virtual bool isValidPath(const Path & path) = 0;
 
+    /* Query the set of valid paths. */
+    virtual PathSet queryValidPaths() = 0;
+
     /* Queries the hash of a valid path. */ 
     virtual Hash queryPathHash(const Path & path) = 0;
 
@@ -43,21 +132,40 @@ public:
     virtual void queryReferences(const Path & path,
         PathSet & references) = 0;
 
+    /* Like queryReferences, but with self-references filtered out. */
+    PathSet queryReferencesNoSelf(const Path & path)
+    {
+        PathSet res;
+        queryReferences(path, res);
+        res.erase(path);
+        return res;
+    }
+
     /* Queries the set of incoming FS references for a store path.
        The result is not cleared. */
     virtual void queryReferrers(const Path & path,
         PathSet & referrers) = 0;
 
+    /* Like queryReferrers, but with self-references filtered out. */
+    PathSet queryReferrersNoSelf(const Path & path)
+    {
+        PathSet res;
+        queryReferrers(path, res);
+        res.erase(path);
+        return res;
+    }
+
     /* Query the deriver of a store path.  Return the empty string if
        no deriver has been set. */
     virtual Path queryDeriver(const Path & path) = 0;
 
-    /* Query the set of substitutable paths. */
-    virtual PathSet querySubstitutablePaths() = 0;
+    /* Query whether a path has substitutes. */
+    virtual bool hasSubstitutes(const Path & path) = 0;
 
-    /* More efficient variant if we just want to know if a path has
-       substitutes. */
-    virtual bool hasSubstitutes(const Path & path);
+    /* Query the references, deriver and download size of a
+       substitutable path. */
+    virtual bool querySubstitutablePathInfo(const Path & path,
+        SubstitutablePathInfo & info) = 0;
     
     /* Copy the contents of a path to the store and register the
        validity the resulting path.  The resulting path is returned.
@@ -134,33 +242,8 @@ public:
        outside of the Nix store that point to `storePath'.  */
     virtual Roots findRoots() = 0;
 
-    /* Depending on `action', this function does the following:
-
-       - `gcReturnRoots': find and return the set of roots for the
-         garbage collector.  These are the store paths symlinked to in
-         the `gcroots' directory.
-
-       - `gcReturnLive': return the set of paths reachable from
-         (i.e. in the closure of) the roots.
-
-       - `gcReturnDead': return the set of paths not reachable from
-         the roots.
-
-       - `gcDeleteDead': actually delete the latter set.
-
-       - `gcDeleteSpecific': delete the paths listed in
-         `pathsToDelete', insofar as they are not reachable.
-
-       If `ignoreLiveness' is set, then reachability from the roots is
-       ignored (dangerous!).  However, the paths must still be
-       unreferenced *within* the store (i.e., there can be no other
-       store paths that depend on them).
-
-       For `gcReturnDead', `gcDeleteDead' and `gcDeleteSpecific', the
-       number of bytes that would be or was freed is returned in
-       `bytesFreed'. */
-    virtual void collectGarbage(GCAction action, const PathSet & pathsToDelete,
-        bool ignoreLiveness, PathSet & result, unsigned long long & bytesFreed) = 0;
+    /* Perform a garbage collection. */
+    virtual void collectGarbage(const GCOptions & options, GCResults & results) = 0;
 };
 
 
@@ -174,11 +257,21 @@ bool isStorePath(const Path & path);
 
 void checkStoreName(const string & name);
 
+
 /* Chop off the parts after the top-level store name, e.g.,
    /nix/store/abcd-foo/bar => /nix/store/abcd-foo. */
 Path toStorePath(const Path & path);
 
 
+/* Follow symlinks until we end up with a path in the Nix store. */
+Path followLinksToStore(const Path & path);
+
+
+/* Same as followLinksToStore(), but apply toStorePath() to the
+   result. */
+Path followLinksToStorePath(const Path & path);
+
+
 /* Constructs a unique store path name. */
 Path makeStorePath(const string & type,
     const Hash & hash, const string & suffix);
@@ -236,18 +329,31 @@ extern boost::shared_ptr<StoreAPI> store;
 
 /* Factory method: open the Nix database, either through the local or
    remote implementation. */
-boost::shared_ptr<StoreAPI> openStore(bool reserveSpace = true);
+boost::shared_ptr<StoreAPI> openStore();
 
 
+/* Display a set of paths in human-readable form (i.e., between quotes
+   and separated by commas). */
+string showPaths(const PathSet & paths);
+
+
+string makeValidityRegistration(const PathSet & paths,
+    bool showDerivers, bool showHash);
+    
 struct ValidPathInfo 
 {
     Path path;
     Path deriver;
     Hash hash;
     PathSet references;
+    time_t registrationTime;
+    ValidPathInfo() : registrationTime(0) { }
 };
 
-ValidPathInfo decodeValidPathInfo(std::istream & str);
+typedef list<ValidPathInfo> ValidPathInfos;
+
+ValidPathInfo decodeValidPathInfo(std::istream & str,
+    bool hashGiven = false);
 
 
 }

src/libstore/upgrade-schema.cc

@@ -0,0 +1,108 @@
+#include "db.hh"
+#include "hash.hh"
+#include "util.hh"
+#include "local-store.hh"
+#include "globals.hh"
+#include "pathlocks.hh"
+#include "config.h"
+
+#include <iostream>
+
+
+namespace nix {
+
+
+Hash parseHashField(const Path & path, const string & s);
+
+
+/* Upgrade from schema 4 (Nix 0.11) to schema 5 (Nix >= 0.12).  The
+   old schema uses Berkeley DB, the new one stores store path
+   meta-information in files. */
+void LocalStore::upgradeStore12()
+{
+#if OLD_DB_COMPAT
+    
+#ifdef __CYGWIN__
+    /* Cygwin can't upgrade a read lock to a write lock... */
+    lockFile(globalLock, ltNone, true);
+#endif
+
+    if (!lockFile(globalLock, ltWrite, false)) {
+        printMsg(lvlError, "waiting for exclusive access to the Nix store...");
+        lockFile(globalLock, ltWrite, true);
+    }
+
+    printMsg(lvlError, "upgrading Nix store to new schema (this may take a while)...");
+
+    if (getSchema() >= nixSchemaVersion) return; /* somebody else beat us to it */
+
+    /* Open the old Nix database and tables. */
+    Database nixDB;
+    nixDB.open(nixDBPath);
+    
+    /* dbValidPaths :: Path -> ()
+
+       The existence of a key $p$ indicates that path $p$ is valid
+       (that is, produced by a succesful build). */
+    TableId dbValidPaths = nixDB.openTable("validpaths");
+
+    /* dbReferences :: Path -> [Path]
+
+       This table lists the outgoing file system references for each
+       output path that has been built by a Nix derivation.  These are
+       found by scanning the path for the hash components of input
+       paths. */
+    TableId dbReferences = nixDB.openTable("references");
+
+    /* dbReferrers :: Path -> Path
+
+       This table is just the reverse mapping of dbReferences.  This
+       table can have duplicate keys, each corresponding value
+       denoting a single referrer. */
+    // Not needed for conversion: it's just the inverse of
+    // references.
+    // TableId dbReferrers = nixDB.openTable("referrers");
+
+    /* dbDerivers :: Path -> [Path]
+
+       This table lists the derivation used to build a path.  There
+       can only be multiple such paths for fixed-output derivations
+       (i.e., derivations specifying an expected hash). */
+    TableId dbDerivers = nixDB.openTable("derivers");
+
+    Paths paths;
+    nixDB.enumTable(noTxn, dbValidPaths, paths);
+    
+    for (Paths::iterator i = paths.begin(); i != paths.end(); ++i) {
+        ValidPathInfo info;
+        info.path = *i;
+        
+        Paths references;
+        nixDB.queryStrings(noTxn, dbReferences, *i, references);
+        info.references.insert(references.begin(), references.end());
+        
+        string s;
+        nixDB.queryString(noTxn, dbValidPaths, *i, s);
+        info.hash = parseHashField(*i, s);
+        
+        nixDB.queryString(noTxn, dbDerivers, *i, info.deriver);
+        
+        registerValidPath(info, true);
+        std::cerr << ".";
+    }
+
+    std::cerr << std::endl;
+
+    writeFile(schemaPath, (format("%1%") % nixSchemaVersion).str());
+
+    lockFile(globalLock, ltRead, true);
+
+#else
+    throw Error(
+        "Your Nix store has a database in Berkeley DB format. To convert\n"
+        "to the new format, please compile Nix with Berkeley DB support.");
+#endif
+}
+
+
+}

src/libstore/worker-protocol.hh

@@ -8,30 +8,32 @@ namespace nix {
 #define WORKER_MAGIC_1 0x6e697863
 #define WORKER_MAGIC_2 0x6478696f
 
-#define PROTOCOL_VERSION 0x101
+#define PROTOCOL_VERSION 0x104
 #define GET_PROTOCOL_MAJOR(x) ((x) & 0xff00)
+#define GET_PROTOCOL_MINOR(x) ((x) & 0x00ff)
 
 
 typedef enum {
     wopQuit = 0,
-    wopIsValidPath,
+    wopIsValidPath = 1,
     wopHasSubstitutes = 3,
-    wopQueryPathHash,
-    wopQueryReferences,
-    wopQueryReferrers,
-    wopAddToStore,
-    wopAddTextToStore,
-    wopBuildDerivations,
-    wopEnsurePath,
-    wopAddTempRoot,
-    wopAddIndirectRoot,
-    wopSyncWithGC,
-    wopFindRoots,
-    wopCollectGarbage,
-    wopExportPath,
-    wopImportPath,
-    wopQueryDeriver,
-    wopSetOptions,
+    wopQueryPathHash = 4,
+    wopQueryReferences = 5,
+    wopQueryReferrers = 6,
+    wopAddToStore = 7,
+    wopAddTextToStore = 8,
+    wopBuildDerivations = 9,
+    wopEnsurePath = 10,
+    wopAddTempRoot = 11,
+    wopAddIndirectRoot = 12,
+    wopSyncWithGC = 13,
+    wopFindRoots = 14,
+    wopExportPath = 16,
+    wopImportPath = 17,
+    wopQueryDeriver = 18,
+    wopSetOptions = 19,
+    wopCollectGarbage = 20,
+    wopQuerySubstitutablePathInfo = 21,
 } WorkerOp;
 
 

src/libutil/aterm.cc

@@ -1,5 +1,7 @@
 #include "aterm.hh"
 
+#include <cstring>
+
 using std::string;
 
 

src/libutil/hash.cc

@@ -1,6 +1,7 @@
 #include "config.h"
 
 #include <iostream>
+#include <cstring>
 
 #ifdef HAVE_OPENSSL
 #include <openssl/md5.h>

src/libutil/hash.hh

@@ -83,7 +83,7 @@ Hash compressHash(const Hash & hash, unsigned int newSize);
 HashType parseHashType(const string & s);
 
 
-typedef union Ctx;
+union Ctx;
 
 class HashSink : public Sink
 {

src/libutil/serialise.cc

@@ -1,6 +1,8 @@
 #include "serialise.hh"
 #include "util.hh"
 
+#include <cstring>
+
 
 namespace nix {
 
@@ -39,6 +41,21 @@ void writeInt(unsigned int n, Sink & sink)
 }
 
 
+void writeLongLong(unsigned long long n, Sink & sink)
+{
+    unsigned char buf[8];
+    buf[0] = n & 0xff;
+    buf[1] = (n >> 8) & 0xff;
+    buf[2] = (n >> 16) & 0xff;
+    buf[3] = (n >> 24) & 0xff;
+    buf[4] = (n >> 32) & 0xff;
+    buf[5] = (n >> 40) & 0xff;
+    buf[6] = (n >> 48) & 0xff;
+    buf[7] = (n >> 56) & 0xff;
+    sink(buf, sizeof(buf));
+}
+
+
 void writeString(const string & s, Sink & sink)
 {
     unsigned int len = s.length();
@@ -82,6 +99,22 @@ unsigned int readInt(Source & source)
 }
 
 
+unsigned long long readLongLong(Source & source)
+{
+    unsigned char buf[8];
+    source(buf, sizeof(buf));
+    return
+        ((unsigned long long) buf[0]) |
+        ((unsigned long long) buf[1] << 8) |
+        ((unsigned long long) buf[2] << 16) |
+        ((unsigned long long) buf[3] << 24) |
+        ((unsigned long long) buf[4] << 32) |
+        ((unsigned long long) buf[5] << 40) |
+        ((unsigned long long) buf[6] << 48) |
+        ((unsigned long long) buf[7] << 56);
+}
+
+
 string readString(Source & source)
 {
     unsigned int len = readInt(source);

src/libutil/serialise.hh

@@ -95,11 +95,13 @@ struct StringSource : Source
 
 void writePadding(unsigned int len, Sink & sink);
 void writeInt(unsigned int n, Sink & sink);
+void writeLongLong(unsigned long long n, Sink & sink);
 void writeString(const string & s, Sink & sink);
 void writeStringSet(const StringSet & ss, Sink & sink);
 
 void readPadding(unsigned int len, Source & source);
 unsigned int readInt(Source & source);
+unsigned long long readLongLong(Source & source);
 string readString(Source & source);
 StringSet readStringSet(Source & source);
 

src/libutil/util.cc

@@ -7,7 +7,9 @@
 #include <iostream>
 #include <cerrno>
 #include <cstdio>
+#include <cstdlib>
 #include <sstream>
+#include <cstring>
 
 #include <sys/stat.h>
 #include <sys/wait.h>
@@ -105,8 +107,7 @@ Path canonPath(const Path & path, bool resolveSymlinks)
             /* If s points to a symlink, resolve it and restart (since
                the symlink target might contain new symlinks). */
             if (resolveSymlinks && isLink(s)) {
-                followCount++;
-                if (followCount >= maxFollow)
+                if (++followCount >= maxFollow)
                     throw Error(format("infinite symlink recursion in path `%1%'") % path);
                 temp = absPath(readLink(s), dirOf(s))
                     + string(i, end);
@@ -228,30 +229,38 @@ void writeFile(const Path & path, const string & s)
 }
 
 
-unsigned long long computePathSize(const Path & path)
+static void _computePathSize(const Path & path,
+    unsigned long long & bytes, unsigned long long & blocks)
 {
-    unsigned long long size = 0;
-    
     checkInterrupt();
 
     struct stat st;
     if (lstat(path.c_str(), &st))
 	throw SysError(format("getting attributes of path `%1%'") % path);
 
-    size += st.st_size;
+    bytes += st.st_size;
+    blocks += st.st_blocks;
 
     if (S_ISDIR(st.st_mode)) {
 	Strings names = readDirectory(path);
 
 	for (Strings::iterator i = names.begin(); i != names.end(); ++i)
-            size += computePathSize(path + "/" + *i);
+            _computePathSize(path + "/" + *i, bytes, blocks);
     }
-
-    return size;
 }
 
 
-static void _deletePath(const Path & path, unsigned long long & bytesFreed)
+void computePathSize(const Path & path,
+    unsigned long long & bytes, unsigned long long & blocks)
+{
+    bytes = 0;
+    blocks = 0;
+    _computePathSize(path, bytes, blocks);
+}
+
+
+static void _deletePath(const Path & path, unsigned long long & bytesFreed,
+    unsigned long long & blocksFreed)
 {
     checkInterrupt();
 
@@ -262,6 +271,7 @@ static void _deletePath(const Path & path, unsigned long long & bytesFreed)
 	throw SysError(format("getting attributes of path `%1%'") % path);
 
     bytesFreed += st.st_size;
+    blocksFreed += st.st_blocks;
 
     if (S_ISDIR(st.st_mode)) {
 	Strings names = readDirectory(path);
@@ -273,7 +283,7 @@ static void _deletePath(const Path & path, unsigned long long & bytesFreed)
 	}
 
 	for (Strings::iterator i = names.begin(); i != names.end(); ++i)
-            _deletePath(path + "/" + *i, bytesFreed);
+            _deletePath(path + "/" + *i, bytesFreed, blocksFreed);
     }
 
     if (remove(path.c_str()) == -1)
@@ -283,17 +293,19 @@ static void _deletePath(const Path & path, unsigned long long & bytesFreed)
 
 void deletePath(const Path & path)
 {
-    unsigned long long dummy;
-    deletePath(path, dummy);
+    unsigned long long dummy1, dummy2;
+    deletePath(path, dummy1, dummy2);
 }
 
 
-void deletePath(const Path & path, unsigned long long & bytesFreed)
+void deletePath(const Path & path, unsigned long long & bytesFreed,
+    unsigned long long & blocksFreed)
 {
     startNest(nest, lvlDebug,
         format("recursively deleting path `%1%'") % path);
     bytesFreed = 0;
-    _deletePath(path, bytesFreed);
+    blocksFreed = 0;
+    _deletePath(path, bytesFreed, blocksFreed);
 }
 
 
@@ -318,19 +330,27 @@ void makePathReadOnly(const Path & path)
 }
 
 
-static Path tempName(const Path & tmpRoot)
+static Path tempName(Path tmpRoot, const Path & prefix, bool includePid,
+    int & counter)
 {
-    static int counter = 0;
-    Path tmpRoot2 = canonPath(tmpRoot.empty() ? getEnv("TMPDIR", "/tmp") : tmpRoot, true);
-    return (format("%1%/nix-%2%-%3%") % tmpRoot2 % getpid() % counter++).str();
+    tmpRoot = canonPath(tmpRoot.empty() ? getEnv("TMPDIR", "/tmp") : tmpRoot, true);
+    if (includePid)
+        return (format("%1%/%2%-%3%-%4%") % tmpRoot % prefix % getpid() % counter++).str();
+    else
+        return (format("%1%/%2%-%3%") % tmpRoot % prefix % counter++).str();
 }
 
 
-Path createTempDir(const Path & tmpRoot)
+Path createTempDir(const Path & tmpRoot, const Path & prefix,
+    bool includePid, bool useGlobalCounter)
 {
+    static int globalCounter = 0;
+    int localCounter = 0;
+    int & counter(useGlobalCounter ? globalCounter : localCounter);
+    
     while (1) {
         checkInterrupt();
-	Path tmpDir = tempName(tmpRoot);
+	Path tmpDir = tempName(tmpRoot, prefix, includePid, counter);
 	if (mkdir(tmpDir.c_str(), 0777) == 0) {
 	    /* Explicitly set the group of the directory.  This is to
 	       work around around problems caused by BSD's group
@@ -350,13 +370,17 @@ Path createTempDir(const Path & tmpRoot)
 }
 
 
-void createDirs(const Path & path)
+Paths createDirs(const Path & path)
 {
-    if (path == "/") return;
-    createDirs(dirOf(path));
-    if (!pathExists(path))
+    Paths created;
+    if (path == "/") return created;
+    if (!pathExists(path)) {
+        created = createDirs(dirOf(path));
         if (mkdir(path.c_str(), 0777) == -1)
             throw SysError(format("creating directory `%1%'") % path);
+        created.push_back(path);
+    }
+    return created;
 }
 
 
@@ -509,14 +533,26 @@ string drainFD(int fd)
 //////////////////////////////////////////////////////////////////////
 
 
-AutoDelete::AutoDelete(const string & p) : path(p)
+AutoDelete::AutoDelete(const string & p, bool recursive) : path(p)
 {
     del = true;
+    this->recursive = recursive;
 }
 
 AutoDelete::~AutoDelete()
 {
-    if (del) deletePath(path);
+    try {
+        if (del) {
+            if (recursive)
+                deletePath(path);
+            else {
+                if (remove(path.c_str()) == -1)
+                    throw SysError(format("cannot unlink `%1%'") % path);
+            }
+        }
+    } catch (...) {
+        ignoreException();
+    }
 }
 
 void AutoDelete::cancel()
@@ -543,7 +579,14 @@ AutoCloseFD::AutoCloseFD(int fd)
 
 AutoCloseFD::AutoCloseFD(const AutoCloseFD & fd)
 {
-    abort();
+    /* Copying a AutoCloseFD isn't allowed (who should get to close
+       it?).  But as a edge case, allow copying of closed
+       AutoCloseFDs.  This is necessary due to tiresome reasons
+       involving copy constructor use on default object values in STL
+       containers (like when you do `map[value]' where value isn't in
+       the map yet). */
+    this->fd = fd.fd;
+    if (this->fd != -1) abort();
 }
 
 
@@ -752,10 +795,10 @@ void killUser(uid_t uid)
 		if (errno != EINTR)
 		    throw SysError(format("cannot kill processes for uid `%1%'") % uid);
 	    }
-        
+
         } catch (std::exception & e) {
-            std::cerr << format("killing processes beloging to uid `%1%': %1%\n")
-                % uid % e.what();
+            std::cerr << format("killing processes beloging to uid `%1%': %1%")
+                % uid % e.what() << std::endl;
             quickExit(1);
         }
         quickExit(0);
@@ -796,7 +839,7 @@ string runProgram(Path program, bool searchPath, const Strings & args)
             pipe.readSide.close();
 
             if (dup2(pipe.writeSide, STDOUT_FILENO) == -1)
-                throw SysError("dupping from-hook write side");
+                throw SysError("dupping stdout");
 
             std::vector<const char *> cargs; /* careful with c_str()! */
             cargs.push_back(program.c_str());
@@ -832,6 +875,17 @@ string runProgram(Path program, bool searchPath, const Strings & args)
 }
 
 
+void closeMostFDs(const set<int> & exceptions)
+{
+    int maxFD = 0;
+    maxFD = sysconf(_SC_OPEN_MAX);
+    for (int fd = 0; fd < maxFD; ++fd)
+        if (fd != STDIN_FILENO && fd != STDOUT_FILENO && fd != STDERR_FILENO
+            && exceptions.find(fd) == exceptions.end())
+            close(fd); /* ignore result */
+}
+
+
 void quickExit(int status)
 {
 #ifdef __CYGWIN__
@@ -947,8 +1001,15 @@ string statusToString(int status)
     if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
         if (WIFEXITED(status))
             return (format("failed with exit code %1%") % WEXITSTATUS(status)).str();
-        else if (WIFSIGNALED(status))
-            return (format("failed due to signal %1%") % WTERMSIG(status)).str();
+        else if (WIFSIGNALED(status)) {
+	    int sig = WTERMSIG(status);
+#if HAVE_STRSIGNAL
+            const char * description = strsignal(sig);
+            return (format("failed due to signal %1% (%2%)") % sig % description).str();
+#else
+            return (format("failed due to signal %1%") % sig).str();
+#endif
+	}
         else
             return "died abnormally";
     } else return "succeeded";
@@ -977,6 +1038,20 @@ bool string2Int(const string & s, int & n)
 }
 
 
+bool string2Int(const string & s, long long & n)
+{
+    std::istringstream str(s);
+    str >> n;
+    return str && str.get() == EOF;
+}
+
+
+bool hasSuffix(const string & s, const string & suffix)
+{
+    return s.size() >= suffix.size() && string(s, s.size() - suffix.size()) == suffix;
+}
+
+
 void ignoreException()
 {
     try {

src/libutil/util.hh

@@ -12,6 +12,10 @@
 namespace nix {
 
 
+#define foreach(it_type, it, collection)                                \
+    for (it_type it = collection.begin(); it != collection.end(); ++it)
+
+
 /* Return an environment variable. */
 string getEnv(const string & key, const string & def = "");
 
@@ -57,23 +61,27 @@ string readFile(const Path & path);
 void writeFile(const Path & path, const string & s);
 
 /* Compute the sum of the sizes of all files in `path'. */
-unsigned long long computePathSize(const Path & path);
+void computePathSize(const Path & path,
+    unsigned long long & bytes, unsigned long long & blocks);
 
 /* Delete a path; i.e., in the case of a directory, it is deleted
    recursively.  Don't use this at home, kids.  The second variant
-   returns the number of bytes freed. */
+   returns the number of bytes and blocks freed. */
 void deletePath(const Path & path);
 
-void deletePath(const Path & path, unsigned long long & bytesFreed);
+void deletePath(const Path & path, unsigned long long & bytesFreed,
+    unsigned long long & blocksFreed);
 
 /* Make a path read-only recursively. */
 void makePathReadOnly(const Path & path);
 
 /* Create a temporary directory. */
-Path createTempDir(const Path & tmpRoot = "");
+Path createTempDir(const Path & tmpRoot = "", const Path & prefix = "nix",
+    bool includePid = true, bool useGlobalCounter = true);
 
-/* Create a directory and all its parents, if necessary. */
-void createDirs(const Path & path);
+/* Create a directory and all its parents, if necessary.  Returns the
+   list of created directories, in order of creation. */
+Paths createDirs(const Path & path);
 
 /* Create a file and write the given text to it.  The file is written
    in binary mode (i.e., no end-of-line conversions).  The path should
@@ -166,8 +174,9 @@ class AutoDelete
 {
     Path path;
     bool del;
+    bool recursive;    
 public:
-    AutoDelete(const Path & p);
+    AutoDelete(const Path & p, bool recursive = true);
     ~AutoDelete();
     void cancel();
 };
@@ -236,6 +245,10 @@ void killUser(uid_t uid);
 string runProgram(Path program, bool searchPath = false,
     const Strings & args = Strings());
 
+/* Close all file descriptors except stdin, stdout, stderr, and those
+   listed in the given set.  Good practice in child processes. */
+void closeMostFDs(const set<int> & exceptions);
+
 /* Wrapper around _exit() on Unix and ExitProcess() on Windows.  (On
    Cygwin, _exit() doesn't seem to do the right thing.) */
 void quickExit(int status);
@@ -278,6 +291,11 @@ bool statusOk(int status);
 /* Parse a string into an integer. */
 string int2String(int n);
 bool string2Int(const string & s, int & n);
+bool string2Int(const string & s, long long & n);
+
+
+/* Return true iff `s' ends in `suffix'. */
+bool hasSuffix(const string & s, const string & suffix);
 
 
 /* Exception handling in destructors: print an error message, then
@@ -285,6 +303,29 @@ bool string2Int(const string & s, int & n);
 void ignoreException();
 
 
+/* STL functions such as sort() pass a binary function object around
+   by value, so it gets cloned a lot.  This is bad if the function
+   object has state or is simply large.  This adapter wraps the
+   function object to simulate passing by reference. */
+template<class F>
+struct binary_function_ref_adapter
+{
+    F * p;
+
+    binary_function_ref_adapter(F * _p)
+    {
+        p = _p;
+    }
+    
+    typename F::result_type operator () (
+        const typename F::first_argument_type & x,
+        const typename F::second_argument_type & y)
+    {
+        return (*p)(x, y);
+    }
+};
+
+
 }
 
 

src/nix-env/Makefile.am

@@ -1,7 +1,6 @@
 bin_PROGRAMS = nix-env
 
-nix_env_SOURCES = nix-env.cc names.cc names.hh \
- profiles.cc profiles.hh help.txt
+nix_env_SOURCES = nix-env.cc profiles.cc profiles.hh help.txt
 nix_env_LDADD = ../libmain/libmain.la ../libexpr/libexpr.la \
  ../libstore/libstore.la ../libutil/libutil.la \
  ../boost/format/libformat.la ${bdb_lib} ${aterm_lib}

src/nix-env/help.txt

@@ -9,6 +9,7 @@ Operations:
   --set: create a user environment containing a single derivation
   --uninstall / -e: remove derivations from the user environment
   --query / -q: perform a query on an environment or Nix expression
+  --set-flag NAME VALUE: set derivation meta-attribute to given value
 
 The previous operations take a list of derivation names.  The special
 name `*' may be used to indicate all derivations.
@@ -20,8 +21,6 @@ name `*' may be used to indicate all derivations.
   --delete-generations GENERATIONS...: deleted listed generations,
       `old' for all non-current generations
   
-  --import / -I FILE: set default Nix expression
-
   --version: output version information
   --help: display help
 
@@ -55,7 +54,7 @@ Query flags:
   --xml: show output in XML format
   --status / -s: print installed/present status
   --no-name: hide derivation names
-  --attr / -A: shows the unambiguous attribute name of the
+  --attr-path / -P: shows the unambiguous attribute name of the
       derivation which can be used when installing with -A
   --system: print the platform type of the derivation 
   --compare-versions / -c: compare version to available or installed
@@ -63,8 +62,6 @@ Query flags:
   --out-path: print path of derivation output
   --description: print description
   --meta: print all meta attributes (only with --xml)
-  --prebuilt-only: only show derivations whose prebuilt binaries are
-      available on this machine or are downloadable
 
 Options:
 
@@ -74,3 +71,5 @@ Options:
   --keep-failed / -K: keep temporary directories of failed builds
   --preserve-installed: do not replace currently installed versions in `-i'
   --system-filter SYSTEM: only use derivations for specified platform
+  --prebuilt-only / -b: only use derivations whose prebuilt binaries are
+      available on this machine or are downloadable

src/nix-env/nix-env.cc

@@ -13,7 +13,6 @@
 #include "common-opts.hh"
 #include "xml-writer.hh"
 #include "store-api.hh"
-#include "db.hh"
 #include "util.hh"
 
 #include <cerrno>
@@ -47,8 +46,9 @@ struct InstallSourceInfo
     Path nixExprPath; /* for srcNixExprDrvs, srcNixExprs */
     Path profile; /* for srcProfile */
     string systemFilter; /* for srcNixExprDrvs */
+    bool prebuiltOnly;
     ATermMap autoArgs;
-    InstallSourceInfo() : autoArgs() { };
+    InstallSourceInfo() : prebuiltOnly(false) { };
 };
 
 
@@ -94,6 +94,8 @@ static bool parseInstallSourceOptions(Globals & globals,
     }
     else if (arg == "--attr" || arg == "-A")
         globals.instSource.type = srcAttrPath;
+    else if (arg == "--prebuilt-only" || arg == "-b")
+        globals.instSource.prebuiltOnly = true;
     else return false;
     return true;
 }
@@ -113,18 +115,29 @@ static void getAllExprs(EvalState & state,
     const Path & path, ATermMap & attrs)
 {
     Strings names = readDirectory(path);
+    StringSet namesSorted(names.begin(), names.end());
 
-    for (Strings::iterator i = names.begin(); i != names.end(); ++i) {
+    foreach (StringSet::iterator, i, namesSorted) {
         Path path2 = path + "/" + *i;
         
         struct stat st;
         if (stat(path2.c_str(), &st) == -1)
             continue; // ignore dangling symlinks in ~/.nix-defexpr
         
-        if (isNixExpr(path2))
-            attrs.set(toATerm(*i), makeAttrRHS(
+        if (isNixExpr(path2)) {
+            /* Strip off the `.nix' filename suffix (if applicable),
+               otherwise the attribute cannot be selected with the
+               `-A' option.  Useful if you want to stick a Nix
+               expression directly in ~/.nix-defexpr. */
+            string attrName = *i;
+            if (hasSuffix(attrName, ".nix"))
+                attrName = string(attrName, 0, attrName.size() - 4);
+            attrs.set(toATerm(attrName), makeAttrRHS(
                     parseExprFromFile(state, absPath(path2)), makeNoPos()));
+        }
         else
+            /* `path2' is a directory (with no default.nix in it);
+               recurse into it. */
             getAllExprs(state, path2, attrs);
     }
 }
@@ -141,7 +154,7 @@ static Expr loadSourceExpr(EvalState & state, const Path & path)
        for a user to have a ~/.nix-defexpr directory that includes
        some system-wide directory). */
     ATermMap attrs;
-    attrs.set(toATerm("_combineChannels"), makeAttrRHS(eTrue, makeNoPos()));
+    attrs.set(toATerm("_combineChannels"), makeAttrRHS(makeList(ATempty), makeNoPos()));
     getAllExprs(state, path, attrs);
     return makeAttrs(attrs);
 }
@@ -213,8 +226,34 @@ static DrvInfos queryInstalled(EvalState & state, const Path & userEnv)
 }
 
 
-static void createUserEnv(EvalState & state, const DrvInfos & elems,
-    const Path & profile, bool keepDerivations)
+/* Ensure exclusive access to a profile.  Any command that modifies
+   the profile first acquires this lock. */
+static void lockProfile(PathLocks & lock, const Path & profile)
+{
+    lock.lockPaths(singleton<PathSet>(profile),
+        (format("waiting for lock on profile `%1%'") % profile).str());
+    lock.setDeletion(true);
+}
+
+
+/* Optimistic locking is used by long-running operations like `nix-env
+   -i'.  Instead of acquiring the exclusive lock for the entire
+   duration of the operation, we just perform the operation
+   optimistically (without an exclusive lock), and check at the end
+   whether the profile changed while we were busy (i.e., the symlink
+   target changed).  If so, the operation is restarted.  Restarting is
+   generally cheap, since the build results are still in the Nix
+   store.  Most of the time, only the user environment has to be
+   rebuilt. */
+static string optimisticLockProfile(const Path & profile)
+{
+    return pathExists(profile) ? readLink(profile) : "";
+}
+
+
+static bool createUserEnv(EvalState & state, const DrvInfos & elems,
+    const Path & profile, bool keepDerivations,
+    const string & lockToken)
 {
     /* Build the components in the user environment, if they don't
        exist already. */
@@ -245,8 +284,14 @@ static void createUserEnv(EvalState & state, const DrvInfos & elems,
            output path, and optionally the derivation path, as well as
            the meta attributes. */
         Path drvPath = keepDerivations ? i->queryDrvPath(state) : "";
+
+        MetaInfo meta = i->queryMetaInfo(state);
+        ATermList metaList = ATempty;
+        foreach (MetaInfo::iterator, j, meta)
+            metaList = ATinsert(metaList,
+                makeBind(toATerm(j->first), makeStr(j->second), makeNoPos()));
         
-        ATermList as = ATmakeList4(
+        ATermList as = ATmakeList5(
             makeBind(toATerm("type"),
                 makeStr("derivation"), makeNoPos()),
             makeBind(toATerm("name"),
@@ -254,17 +299,13 @@ static void createUserEnv(EvalState & state, const DrvInfos & elems,
             makeBind(toATerm("system"),
                 makeStr(i->system), makeNoPos()),
             makeBind(toATerm("outPath"),
-                makeStr(i->queryOutPath(state)), makeNoPos()));
+                makeStr(i->queryOutPath(state)), makeNoPos()), 
+            makeBind(toATerm("meta"), makeAttrs(metaList), makeNoPos()));
         
         if (drvPath != "") as = ATinsert(as, 
             makeBind(toATerm("drvPath"),
                 makeStr(drvPath), makeNoPos()));
         
-        if (i->attrs->get(toATerm("meta"))) as = ATinsert(as, 
-            makeBind(toATerm("meta"),
-                strictEvalExpr(state, i->attrs->get(toATerm("meta"))),
-                makeNoPos()));
-
         manifest = ATinsert(manifest, makeAttrs(as));
         
         inputs = ATinsert(inputs, makeStr(i->queryOutPath(state)));
@@ -303,9 +344,20 @@ static void createUserEnv(EvalState & state, const DrvInfos & elems,
     store->buildDerivations(singleton<PathSet>(topLevelDrv.queryDrvPath(state)));
 
     /* Switch the current user environment to the output path. */
+    PathLocks lock;
+    lockProfile(lock, profile);
+
+    Path lockTokenCur = optimisticLockProfile(profile);
+    if (lockToken != lockTokenCur) {
+        printMsg(lvlError, format("profile `%1%' changed while we were busy; restarting") % profile);
+        return false;
+    }
+    
     debug(format("switching to new user environment"));
     Path generation = createGeneration(profile, topLevelDrv.queryOutPath(state));
     switchLink(profile, generation);
+
+    return true;
 }
 
 
@@ -319,9 +371,16 @@ static int comparePriorities(EvalState & state,
 }
 
 
-static DrvInfos filterBySelector(EvalState & state,
-    const DrvInfos & allElems,
-    const Strings & args, bool newestOnly)
+static bool isPrebuilt(EvalState & state, const DrvInfo & elem)
+{
+    return
+        store->isValidPath(elem.queryOutPath(state)) ||
+        store->hasSubstitutes(elem.queryOutPath(state));
+}
+
+
+static DrvInfos filterBySelector(EvalState & state, const DrvInfos & allElems,
+    const Strings & args, bool newestOnly, bool prebuiltOnly)
 {
     DrvNames selectors = drvNamesFromArgs(args);
 
@@ -340,7 +399,8 @@ static DrvInfos filterBySelector(EvalState & state,
             DrvName drvName(j->name);
             if (i->matches(drvName)) {
                 i->hits++;
-                matches.push_back(std::pair<DrvInfo, unsigned int>(*j, n));
+                if (!prebuiltOnly || isPrebuilt(state, *j))
+                    matches.push_back(std::pair<DrvInfo, unsigned int>(*j, n));
             }
         }
 
@@ -399,7 +459,7 @@ static DrvInfos filterBySelector(EvalState & state,
     /* Check that all selectors have been used. */
     for (DrvNames::iterator i = selectors.begin();
          i != selectors.end(); ++i)
-        if (i->hits == 0)
+        if (i->hits == 0 && i->fullName != "*")
             throw Error(format("selector `%1%' matches no derivations")
                 % i->fullName);
 
@@ -407,12 +467,18 @@ static DrvInfos filterBySelector(EvalState & state,
 }
 
 
+static bool isPath(const string & s)
+{
+    return s.find('/') != string::npos;
+}
+
+
 static void queryInstSources(EvalState & state,
     const InstallSourceInfo & instSource, const Strings & args,
     DrvInfos & elems, bool newestOnly)
 {
     InstallSourceType type = instSource.type;
-    if (type == srcUnknown && args.size() > 0 && args.front()[0] == '/')
+    if (type == srcUnknown && args.size() > 0 && isPath(args.front()))
         type = srcStorePaths;
     
     switch (type) {
@@ -429,7 +495,8 @@ static void queryInstSources(EvalState & state,
             loadDerivations(state, instSource.nixExprPath,
                 instSource.systemFilter, instSource.autoArgs, "", allElems);
 
-            elems = filterBySelector(state, allElems, args, newestOnly);
+            elems = filterBySelector(state, allElems, args,
+                newestOnly, instSource.prebuiltOnly);
     
             break;
         }
@@ -463,23 +530,23 @@ static void queryInstSources(EvalState & state,
             for (Strings::const_iterator i = args.begin();
                  i != args.end(); ++i)
             {
-                assertStorePath(*i);
+                Path path = followLinksToStorePath(*i);
 
                 DrvInfo elem;
                 elem.attrs = boost::shared_ptr<ATermMap>(new ATermMap(0)); /* ugh... */
-                string name = baseNameOf(*i);
+                string name = baseNameOf(path);
                 string::size_type dash = name.find('-');
                 if (dash != string::npos)
                     name = string(name, dash + 1);
 
-                if (isDerivation(*i)) {
-                    elem.setDrvPath(*i);
-                    elem.setOutPath(findOutput(derivationFromPath(*i), "out"));
+                if (isDerivation(path)) {
+                    elem.setDrvPath(path);
+                    elem.setOutPath(findOutput(derivationFromPath(path), "out"));
                     if (name.size() >= drvExtension.size() &&
                         string(name, name.size() - drvExtension.size()) == drvExtension)
                         name = string(name, 0, name.size() - drvExtension.size());
                 }
-                else elem.setOutPath(*i);
+                else elem.setOutPath(path);
 
                 elem.name = name;
 
@@ -495,7 +562,7 @@ static void queryInstSources(EvalState & state,
         case srcProfile: {
             elems = filterBySelector(state,
                 queryInstalled(state, instSource.profile),
-                args, newestOnly);
+                args, newestOnly, instSource.prebuiltOnly);
             break;
         }
 
@@ -514,8 +581,8 @@ static void queryInstSources(EvalState & state,
 
 static void printMissing(EvalState & state, const DrvInfos & elems)
 {
-    PathSet targets, willBuild, willSubstitute;
-    for (DrvInfos::const_iterator i = elems.begin(); i != elems.end(); ++i) {
+    PathSet targets;
+    foreach (DrvInfos::const_iterator, i, elems) {
         Path drvPath = i->queryDrvPath(state);
         if (drvPath != "")
             targets.insert(drvPath);
@@ -523,27 +590,7 @@ static void printMissing(EvalState & state, const DrvInfos & elems)
             targets.insert(i->queryOutPath(state));
     }
 
-    queryMissing(targets, willBuild, willSubstitute);
-
-    if (!willBuild.empty()) {
-        printMsg(lvlInfo, format("the following derivations will be built:"));
-        for (PathSet::iterator i = willBuild.begin(); i != willBuild.end(); ++i)
-            printMsg(lvlInfo, format("  %1%") % *i);
-    }
-
-    if (!willSubstitute.empty()) {
-        printMsg(lvlInfo, format("the following paths will be substituted:"));
-        for (PathSet::iterator i = willSubstitute.begin(); i != willSubstitute.end(); ++i)
-            printMsg(lvlInfo, format("  %1%") % *i);
-    }
-}
-
-
-static void lockProfile(PathLocks & lock, const Path & profile)
-{
-    lock.lockPaths(singleton<PathSet>(profile),
-        (format("waiting for lock on profile `%1%'") % profile).str());
-    lock.setDeletion(true);
+    printMissing(targets);
 }
 
 
@@ -569,36 +616,35 @@ static void installDerivations(Globals & globals,
 
     /* Add in the already installed derivations, unless they have the
        same name as a to-be-installed element. */
-    PathLocks lock;
-    lockProfile(lock, profile);
-    DrvInfos installedElems = queryInstalled(globals.state, profile);
 
-    DrvInfos allElems(newElems);
-    for (DrvInfos::iterator i = installedElems.begin();
-         i != installedElems.end(); ++i)
-    {
-        DrvName drvName(i->name);
-        MetaInfo meta = i->queryMetaInfo(globals.state);
-        if (!globals.preserveInstalled &&
-            newNames.find(drvName.name) != newNames.end() &&
-            meta["keep"] != "true")
-            printMsg(lvlInfo,
-                format("replacing old `%1%'") % i->name);
-        else
-            allElems.push_back(*i);
-    }
-
-    for (DrvInfos::iterator i = newElems.begin(); i != newElems.end(); ++i)
-        printMsg(lvlInfo,
-            format("installing `%1%'") % i->name);
+    while (true) {
+        string lockToken = optimisticLockProfile(profile);
         
-    if (globals.dryRun) {
-        printMissing(globals.state, newElems);
-        return;
-    }
+        DrvInfos installedElems = queryInstalled(globals.state, profile);
+        
+        DrvInfos allElems(newElems);
+        foreach (DrvInfos::iterator, i, installedElems) {
+            DrvName drvName(i->name);
+            MetaInfo meta = i->queryMetaInfo(globals.state);
+            if (!globals.preserveInstalled &&
+                newNames.find(drvName.name) != newNames.end() &&
+                meta["keep"] != "true")
+                printMsg(lvlInfo,
+                    format("replacing old `%1%'") % i->name);
+            else
+                allElems.push_back(*i);
+        }
 
-    createUserEnv(globals.state, allElems,
-        profile, globals.keepDerivations);
+        foreach (DrvInfos::iterator, i, newElems)
+            printMsg(lvlInfo, format("installing `%1%'") % i->name);
+    
+        printMissing(globals.state, newElems);
+    
+        if (globals.dryRun) return;
+
+        if (createUserEnv(globals.state, allElems,
+                profile, globals.keepDerivations, lockToken)) break;
+    }
 }
 
 
@@ -630,78 +676,75 @@ static void upgradeDerivations(Globals & globals,
        for a derivation in the input Nix expression that has the same
        name and a higher version number. */
 
-    /* Load the currently installed derivations. */
-    PathLocks lock;
-    lockProfile(lock, globals.profile);
-    DrvInfos installedElems = queryInstalled(globals.state, globals.profile);
+    while (true) {
+        string lockToken = optimisticLockProfile(globals.profile);
+        
+        DrvInfos installedElems = queryInstalled(globals.state, globals.profile);
 
-    /* Fetch all derivations from the input file. */
-    DrvInfos availElems;
-    queryInstSources(globals.state, globals.instSource, args, availElems, false);
+        /* Fetch all derivations from the input file. */
+        DrvInfos availElems;
+        queryInstSources(globals.state, globals.instSource, args, availElems, false);
 
-    /* Go through all installed derivations. */
-    DrvInfos newElems;
-    for (DrvInfos::iterator i = installedElems.begin();
-         i != installedElems.end(); ++i)
-    {
-        DrvName drvName(i->name);
+        /* Go through all installed derivations. */
+        DrvInfos newElems;
+        foreach (DrvInfos::iterator, i, installedElems) {
+            DrvName drvName(i->name);
 
-        MetaInfo meta = i->queryMetaInfo(globals.state);
-        if (meta["keep"] == "true") {
-            newElems.push_back(*i);
-            continue;
-        }
+            MetaInfo meta = i->queryMetaInfo(globals.state);
+            if (meta["keep"] == "true") {
+                newElems.push_back(*i);
+                continue;
+            }
 
-        /* Find the derivation in the input Nix expression with the
-           same name that satisfies the version constraints specified
-           by upgradeType.  If there are multiple matches, take the
-           one with the highest priority.  If there are still multiple
-           matches, take the one with the highest version. */
-        DrvInfos::iterator bestElem = availElems.end();
-        DrvName bestName;
-        for (DrvInfos::iterator j = availElems.begin();
-             j != availElems.end(); ++j)
-        {
-            DrvName newName(j->name);
-            if (newName.name == drvName.name) {
-                int d = comparePriorities(globals.state, *i, *j);
-                if (d == 0) d = compareVersions(drvName.version, newName.version);
-                if (upgradeType == utLt && d < 0 ||
-                    upgradeType == utLeq && d <= 0 ||
-                    upgradeType == utEq && d == 0 ||
-                    upgradeType == utAlways)
-                {
-                    int d2 = -1;
-                    if (bestElem != availElems.end()) {
-                        d2 = comparePriorities(globals.state, *bestElem, *j);
-                        if (d2 == 0) d2 = compareVersions(bestName.version, newName.version);
-                    }
-                    if (d2 < 0) {
-                        bestElem = j;
-                        bestName = newName;
+            /* Find the derivation in the input Nix expression with
+               the same name that satisfies the version constraints
+               specified by upgradeType.  If there are multiple
+               matches, take the one with the highest priority.  If
+               there are still multiple matches, take the one with the
+               highest version. */
+            DrvInfos::iterator bestElem = availElems.end();
+            DrvName bestName;
+            foreach (DrvInfos::iterator, j, availElems) {
+                DrvName newName(j->name);
+                if (newName.name == drvName.name) {
+                    int d = comparePriorities(globals.state, *i, *j);
+                    if (d == 0) d = compareVersions(drvName.version, newName.version);
+                    if (upgradeType == utLt && d < 0 ||
+                        upgradeType == utLeq && d <= 0 ||
+                        upgradeType == utEq && d == 0 ||
+                        upgradeType == utAlways)
+                    {
+                        int d2 = -1;
+                        if (bestElem != availElems.end()) {
+                            d2 = comparePriorities(globals.state, *bestElem, *j);
+                            if (d2 == 0) d2 = compareVersions(bestName.version, newName.version);
+                        }
+                        if (d2 < 0) {
+                            bestElem = j;
+                            bestName = newName;
+                        }
                     }
                 }
             }
-        }
 
-        if (bestElem != availElems.end() &&
-            i->queryOutPath(globals.state) !=
+            if (bestElem != availElems.end() &&
+                i->queryOutPath(globals.state) !=
                 bestElem->queryOutPath(globals.state))
-        {
-            printMsg(lvlInfo,
-                format("upgrading `%1%' to `%2%'")
-                % i->name % bestElem->name);
-            newElems.push_back(*bestElem);
-        } else newElems.push_back(*i);
-    }
+            {
+                printMsg(lvlInfo,
+                    format("upgrading `%1%' to `%2%'")
+                    % i->name % bestElem->name);
+                newElems.push_back(*bestElem);
+            } else newElems.push_back(*i);
+        }
     
-    if (globals.dryRun) {
         printMissing(globals.state, newElems);
-        return;
-    }
+    
+        if (globals.dryRun) return;
 
-    createUserEnv(globals.state, newElems,
-        globals.profile, globals.keepDerivations);
+        if (createUserEnv(globals.state, newElems,
+                globals.profile, globals.keepDerivations, lockToken)) break;
+    }
 }
 
 
@@ -745,29 +788,27 @@ static void opSetFlag(Globals & globals,
     string flagValue = *arg++;
     DrvNames selectors = drvNamesFromArgs(Strings(arg, opArgs.end()));
 
-    /* Load the currently installed derivations. */
-    PathLocks lock;
-    lockProfile(lock, globals.profile);
-    DrvInfos installedElems = queryInstalled(globals.state, globals.profile);
+    while (true) {
+        string lockToken = optimisticLockProfile(globals.profile);
 
-    /* Update all matching derivations. */
-    for (DrvInfos::iterator i = installedElems.begin();
-         i != installedElems.end(); ++i)
-    {
-        DrvName drvName(i->name);
-        for (DrvNames::iterator j = selectors.begin();
-             j != selectors.end(); ++j)
-            if (j->matches(drvName)) {
-                printMsg(lvlInfo,
-                    format("setting flag on `%1%'") % i->name);
-                setMetaFlag(globals.state, *i, flagName, flagValue);
-                break;
-            }
+        DrvInfos installedElems = queryInstalled(globals.state, globals.profile);
+
+        /* Update all matching derivations. */
+        foreach (DrvInfos::iterator, i, installedElems) {
+            DrvName drvName(i->name);
+            foreach (DrvNames::iterator, j, selectors)
+                if (j->matches(drvName)) {
+                    printMsg(lvlInfo,
+                        format("setting flag on `%1%'") % i->name);
+                    setMetaFlag(globals.state, *i, flagName, flagValue);
+                    break;
+                }
+        }
+
+        /* Write the new user environment. */
+        if (createUserEnv(globals.state, installedElems,
+                globals.profile, globals.keepDerivations, lockToken)) break;
     }
-
-    /* Write the new user environment. */
-    createUserEnv(globals.state, installedElems,
-        globals.profile, globals.keepDerivations);
 }
 
 
@@ -788,10 +829,17 @@ static void opSet(Globals & globals,
     
     DrvInfo & drv(elems.front());
 
-    if (drv.queryDrvPath(globals.state) != "")
-        store->buildDerivations(singleton<PathSet>(drv.queryDrvPath(globals.state)));
-    else
+    if (drv.queryDrvPath(globals.state) != "") {
+        PathSet paths = singleton<PathSet>(drv.queryDrvPath(globals.state));
+        printMissing(paths);
+        if (globals.dryRun) return;
+        store->buildDerivations(paths);
+    }
+    else {
+        printMissing(singleton<PathSet>(drv.queryOutPath(globals.state)));
+        if (globals.dryRun) return;
         store->ensurePath(drv.queryOutPath(globals.state));
+    }
 
     debug(format("switching to new user environment"));
     Path generation = createGeneration(globals.profile, drv.queryOutPath(globals.state));
@@ -799,34 +847,36 @@ static void opSet(Globals & globals,
 }
 
 
-static void uninstallDerivations(Globals & globals, DrvNames & selectors,
+static void uninstallDerivations(Globals & globals, Strings & selectors,
     Path & profile)
 {
-    PathLocks lock;
-    lockProfile(lock, profile);
-    DrvInfos installedElems = queryInstalled(globals.state, profile);
-    DrvInfos newElems;
+    while (true) {
+        string lockToken = optimisticLockProfile(profile);
 
-    for (DrvInfos::iterator i = installedElems.begin();
-         i != installedElems.end(); ++i)
-    {
-        DrvName drvName(i->name);
-        bool found = false;
-        for (DrvNames::iterator j = selectors.begin();
-             j != selectors.end(); ++j)
-            if (j->matches(drvName)) {
-                printMsg(lvlInfo,
-                    format("uninstalling `%1%'") % i->name);
-                found = true;
-                break;
-            }
-        if (!found) newElems.push_back(*i);
+        DrvInfos installedElems = queryInstalled(globals.state, profile);
+        DrvInfos newElems;
+
+        foreach (DrvInfos::iterator, i, installedElems) {
+            DrvName drvName(i->name);
+            bool found = false;
+            foreach (Strings::iterator, j, selectors)
+                /* !!! the repeated calls to followLinksToStorePath()
+                   are expensive, should pre-compute them. */
+                if ((isPath(*j) && i->queryOutPath(globals.state) == followLinksToStorePath(*j))
+                    || DrvName(*j).matches(drvName))
+                {
+                    printMsg(lvlInfo, format("uninstalling `%1%'") % i->name);
+                    found = true;
+                    break;
+                }
+            if (!found) newElems.push_back(*i);
+        }
+
+        if (globals.dryRun) return;
+
+        if (createUserEnv(globals.state, newElems,
+                profile, globals.keepDerivations, lockToken)) break;
     }
-
-    if (globals.dryRun) return;
-
-    createUserEnv(globals.state, newElems,
-        profile, globals.keepDerivations);
 }
 
 
@@ -835,11 +885,7 @@ static void opUninstall(Globals & globals,
 {
     if (opFlags.size() > 0)
         throw UsageError(format("unknown flag `%1%'") % opFlags.front());
-
-    DrvNames drvNames = drvNamesFromArgs(opArgs);
-
-    uninstallDerivations(globals, drvNames,
-        globals.profile);
+    uninstallDerivations(globals, opArgs, globals.profile);
 }
 
 
@@ -999,7 +1045,7 @@ static void opQuery(Globals & globals,
 
     DrvInfos elems = filterBySelector(globals.state,
         source == sInstalled ? installedElems : availElems,
-        remaining, false);
+        remaining, false, prebuiltOnly);
     
     DrvInfos & otherElems(source == sInstalled ? availElems : installedElems);
 
@@ -1040,12 +1086,6 @@ static void opQuery(Globals & globals,
             /* For XML output. */
             XMLAttrs attrs;
 
-            if (prebuiltOnly) {
-                if (!store->isValidPath(i->queryOutPath(globals.state)) &&
-                    !store->hasSubstitutes(i->queryOutPath(globals.state)))
-                    continue;
-            }
-        
             if (printStatus) {
                 bool hasSubs = store->hasSubstitutes(i->queryOutPath(globals.state));
                 bool isInstalled = installed.find(i->queryOutPath(globals.state)) != installed.end();
@@ -1367,10 +1407,12 @@ void run(Strings args)
             globals.instSource.systemFilter = needArg(i, args, arg);
         else {
             remaining.push_back(arg);
-            if (arg[0] == '-') 
+            if (arg[0] == '-') {
                 opFlags.push_back(arg);
-            else
-                opArgs.push_back(arg);
+                if (arg == "--from-profile") { /* !!! hack */
+                    if (i != args.end()) opFlags.push_back(*i++);
+                }
+            } else opArgs.push_back(arg);
         }
 
         if (oldOp && oldOp != op)

src/nix-log2xml/log2xml.cc

@@ -2,6 +2,7 @@
 #include <iostream>
 #include <cstdio>
 #include <string>
+#include <cstring>
 
 using namespace std;
 

src/nix-store/dotgraph.cc

@@ -1,7 +1,6 @@
 #include "dotgraph.hh"
 #include "util.hh"
 #include "store-api.hh"
-#include "db.hh"
 
 #include <iostream>