In the FFI world we have many tools that are not gcc/clang and therefore
not always support the latest C standard. This fixes support with cffi
i.e. used in https://github.com/tweag/python-nix
(cherry picked from commit 739418504c)
It is not an error if queryPathInfo() indicates that a path does not
exist in the substituter.
Fixes#11198. This was broken in 846869da0e.
(cherry picked from commit 0a00bd07b2)
It was failing with:
error: AWS error fetching 'nix-cache-info': The specified bucket does not exist
because `S3BinaryCacheStoreImpl` had a `bucketName` field that
shadowed the inherited `bucketName from `S3BinaryCacheStoreConfig`.
(cherry picked from commit 9b5b7b7963)
We didn't even realize you *could* use this syntax with -E and -f, much
less that the attribute path could be *empty*.
Change-Id: Id1a6715609f3a76a5ce477bd43a7832effbbe07b
* docs: unify documentation on search paths
- put all the information on search path semantics into `builtins.findFile`
- put all the information on determining the value of `builtins.nixPath` into the
`nix-path` setting
maybe `builtins.nixPath` is a better place for this, but those bits
can still be moved around now that it's all next to each other.
- link to the syntax page for lookup paths from all places that are
concerned with it
- add or clarify examples
- add a test verifying a claim from documentation
Few filesystem-related tests rely on PATH_MAX for buffers, and PATH_MAX
is optional in POSIX (and not available on the Hurd). To make them build
and pass, provide a fallback definition of PATH_MAX in case not
available.
Ideally speaking, the tests ought to not unconditionally rely on
PATH_MAX, do alternative strategies (e.g. dynamically allocate buffers,
expand them as needed, etc); OTOH this is test code, so it would be more
work that what it would be worth, so IMHO the define fallback is good
enough.
Set HOST_HURD & HOST_UNIX for GNU/Hurd in the makefile-based build
system; the latter variable is important as it will include all the
commit Unix bits.
- move <sys/resource.h> from a __linux__ block to a !_WIN32 block: this
matches what the actual code does, using getrlimit() & setrlimit() in
!_WIN32 blocks
- drop <sys/mount.h>, which is not portable, and it is not used
This is not allowed in C++20, and GCC 14 warns about it:
../src/libutil/ref.hh:26:20: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
26 | explicit ref<T>(const std::shared_ptr<T> & p)
| ^
../src/libutil/ref.hh:26:20: note: remove the '< >'
../src/libutil/ref.hh:33:21: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
33 | explicit ref<T>(T * p)
| ^
../src/libutil/ref.hh:33:21: note: remove the '< >'
This change updates the seccomp profile to return ENOTSUP for getxattr
functions family. This reflects the behavior of filesystems that don’t
support extended attributes (or have an option to disable them), e.g.
ext2.
The current behavior is confusing for some programs because we can read
extended attributes, but only get to know that they are not supported
when setting them. In addition to that, ACLs on Linux are implemented
via extended attributes internally and if we don’t return ENOTSUP, acl
library converts file mode to ACL.
https://git.savannah.nongnu.org/cgit/acl.git/tree/libacl/acl_get_file.c?id=d9bb1759d4dad2f28a6dcc8c1742ff75d16dd10d#n69
The internal "completionCallback" and "listPossibleCallback" helpers
are used only when building with editline; hence, do not build then
when using readline, matching their usage in
"ReadlineLikeInteracter::init()".
This seems to have been the intent all along.
The odd combination of unit tests, but no functional tests caused a
build error where some data for the unit test was source-filtered out.
Apparently. It's unclear to me why that happened, so I'm proposing this
alternate "fix" to get the buildNoTests to pass.
It would be nice to test more configurations, but this mode of building
is on the way out anyway, so let's just make it pass and see what
configurations make sense to test as part of the meson migration.
This should make the test more robust, considering the strange hang
in https://hydra.nixos.org/build/267517233/nixlog/8
`builder` seems to have reached `multi-user.target` before the
SSH connection was established, but this seems to be coincidental.
This does tell us that enforcing this has a minimal cost in terms
of runtime.
Waiting for `multi-user.target` on the client is honestly paranoid,
but flaky tests are very bad for productivity.
Trying to learn more about enigmatic spurious hang at
https://hydra.nixos.org/build/267517233/nixlog/8
- builder1 seems to have started properly
- ssh connection and session are established
- ssh client doesn't exit or client.succeed does not return
for some reason.
Seeing the stdout on the console might give a tiny bit more info.
By syncing with Nixpkgs, we reuse the same derivation, which is
generally a good idea, and has the benefit that it is transitively
a channel blocker.
Changes:
- https://github.com/NixOS/nixpkgs/pull/163313 (SuperSandro2000)
> nix: disable big-parallel for aws-sdk-cpp
> aws-sdk-cpp only takes ~1m52s on a 4 core machine under 50% load
> which does not justify the requirement on big parallel.
> Tested with `nix-build -A nixVersions.nix_2_6.aws-sdk-cpp`.
> I can finally build nix without requiring a big-parallel machine.
- https://github.com/NixOS/nixpkgs/pull/227506 (Artturin)
> nix: use [ ] instead null to empty requiredSystemFeatures
> fixes 'error: value is null while a list was expected' with 'nixpkgs.hostPlatform.gcc.arch = "x86_64";'
This was done originally because std::smatch does not accept `const char
*` as iterators. However, this was because we should have been using
std::cmatch instead.
(cherry picked from commit 12a5838d11)
Found by looking for interesting asan reports from the test suite.
What happened here is that name got overwritten, but it was what
actually held the backing memory for the thing it got overwritten by,
which was a by-reference value coming out of std::regex.
Due to absurd reasons I cannot seem to use a string_view iterator here,
so I just copy the string with a longer lifetime instead. idk lol
==3796364==ERROR: AddressSanitizer: heap-use-after-free on address 0x503000014c61 at pc 0x74843523bf1d bp 0x7ffc68351330 sp 0x7ffc68350af0
READ of size 3 at 0x503000014c61 thread T0
0 0x74843523bf1c in __asan_memcpy (/nix/store/mzhqknx2mc94jdz4n320hn1lml86398y-clang-wrapper-17.0.6/resource-root/lib/linux/libclang_rt.asan-x86_64.so+0x159f1c)
1 0x6403cf6cbff4 in std::char_traits<char>::copy(char*, char const*, unsigned long) /nix/store/14c6s4xzhy14i2b05s00rjns2j93gzz4-gcc-13.2.0/include/c++/13.2.0/bits/char_traits.h:445:33
<...>
7 0x6403cf6cbff4 in std::__cxx11::sub_match<__gnu_cxx::__normal_iterator<char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>>>::str() const /nix/store/14c6s4xzhy14i2b05s00rjns2j93gzz4-gcc-13.2.0/include/c++/13.2.0/bits/regex.h:966:6
8 0x6403cf6cbff4 in std::__cxx11::sub_match<__gnu_cxx::__normal_iterator<char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>>>::operator std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>() const /nix/store/14c6s4xzhy14i2b05s00rjns2j93gzz4-gcc-13.2.0/include/c++/13.2.0/bits/regex.h:955:16
9 0x6403cf6cbff4 in nix::getClosureInfo[abi:cxx11](nix::ref<nix::Store>, nix::StorePath const&) /home/jade/lix/lix2/build/src/nix/diff-closures.cc:37:26
10 0x6403cf6cd70c in nix::printClosureDiff(nix::ref<nix::Store>, nix::StorePath const&, nix::StorePath const&, std::basic_string_view<char, std::char_traits<char>>) /home/jade/lix/lix2/build/src/nix/diff-closures.cc:54:25
11 0x6403cf873331 in CmdProfileDiffClosures::run(nix::ref<nix::Store>) /home/jade/lix/lix2/build/src/nix/profile.cc:479:17
<...>
0x503000014c61 is located 17 bytes inside of 21-byte region [0x503000014c50,0x503000014c65)
freed by thread T0 here:
0 0x748435250470 in operator delete(void*) (/nix/store/mzhqknx2mc94jdz4n320hn1lml86398y-clang-wrapper-17.0.6/resource-root/lib/linux/libclang_rt.asan-x86_64.so+0x16e470)
<...>
6 0x6403cf6cbda2 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>::~basic_string() /nix/store/14c6s4xzhy14i2b05s00rjns2j93gzz4-gcc-13.2.0/include/c++/13.2.0/bits/basic_string.h:792:9
7 0x6403cf6cbda2 in nix::getClosureInfo[abi:cxx11](nix::ref<nix::Store>, nix::StorePath const&) /home/jade/lix/lix2/build/src/nix/diff-closures.cc:36:13
8 0x6403cf6cd70c in nix::printClosureDiff(nix::ref<nix::Store>, nix::StorePath const&, nix::StorePath const&, std::basic_string_view<char, std::char_traits<char>>) /home/jade/lix/lix2/build/src/nix/diff-closures.cc:54:25
<...>
previously allocated by thread T0 here:
0 0x74843524fa38 in operator new(unsigned long) (/nix/store/mzhqknx2mc94jdz4n320hn1lml86398y-clang-wrapper-17.0.6/resource-root/lib/linux/libclang_rt.asan-x86_64.so+0x16da38)
<...>
9 0x6403cf6cb68c in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>::basic_string<std::basic_string_view<char, std::char_traits<char>>, void>(std::basic_string_view<char, std::char_traits<char>> const&, std::allocator<char> const&) /nix/store/14c6s4xzhy14i2b05s00rjns2j93gzz4-gcc-13.2.0/include/c++/13.2.0/bits/basic_string.h:784:4
10 0x6403cf6cb68c in nix::getClosureInfo[abi:cxx11](nix::ref<nix::Store>, nix::StorePath const&) /home/jade/lix/lix2/build/src/nix/diff-closures.cc:33:21
11 0x6403cf6cd70c in nix::printClosureDiff(nix::ref<nix::Store>, nix::StorePath const&, nix::StorePath const&, std::basic_string_view<char, std::char_traits<char>>) /home/jade/lix/lix2/build/src/nix/diff-closures.cc:54:25
12 0x6403cf873331 in CmdProfileDiffClosures::run(nix::ref<nix::Store>) /home/jade/lix/lix2/build/src/nix/profile.cc:479:17
<...>
(cherry-picked from b9b1bbd22f)
We should use a metric that weighs the related issues.
Counterbalancing time doesn't make much sense to me.
If it's around for longer, the fix will be relevant to more people.
* manual: Contributing -> Development, Hacking -> Building
what's currently called "hacking" are really instructions for setting up
a development environment and compiling from source. we have
a contribution guide in the repo (which rightly focuses on GitHub
workflows), and the material in the manual is more about working
on the code itself.
since we'd otherwise have three headings that amount to "Building Nix",
this change also moves the "classic Nix" instructions to the top.
we may want to reorganise this in the future, and bring
contributor-oriented information closer to the code, but for now let's
stick to more accurate names to ease navigation.
Meson uses a venerable GNU convention described in
https://www.gnu.org/software/automake/manual/html_node/Scripts_002dbased-Testsuites.html
in which:
> When no test protocol is in use, an exit status of 0 from a test
> script will denote a success, an exit status of 77 a skipped test, an
> exit status of 99 a hard error, and any other exit status will denote
> a failure.
77 is thus what we want, not 99.
* fix NIX_PATH overriding
- test restricted evaluation
- test precedence for setting the search path
Co-authored-by: Robert Hensing <robert@roberthensing.nl>
Co-authored-by: John Ericson <git@JohnEricson.me>
We are piping curl downloads into `unpackTarfileToSink()`, but the
latter is typically slower than the former if you're on a fast
connection. So the download could appear unnecessarily slow. (There is
even a risk that if the Git import is *really* slow for whatever
reason, the TCP connection could time out.)
So let's make the download buffer bigger by default - 64 MiB is big
enough for the Nixpkgs tarball. Perhaps in the future, we could have
an unlimited buffer that spills data to disk beyond a certain
threshold, but that's probably overkill.
Currently, the worker protocol has a version number that we increment
whenever we change something in the protocol. However, this can cause
a collision between Nix PRs / forks that make protocol changes
(e.g. PR #9857 increments the version, which could collide with
another PR). So instead, the client and daemon now exchange a set of
protocol features (such as `auth-forwarding`). They will use the
intersection of the sets of features, i.e. the features they both
support.
Note that protocol features are completely distinct from
`ExperimentalFeature`s.
This is in accordance with ARM's naming convention.
"Low" is confusing, because it could refer to either the cold end
of the stack as an abstract data type, or a low address.
These are different places, because the stack grows down through
the address space.
... as well as match buildReadlineNoMarkdown.
Unfortunately it doesn't support long inputs or multiline inputs
for now.
This needs to make better use of the interacter interface.
In addition to adding the missing thread deps in the last commit, we
also appear to need to skip `-Wl,--as-needed` flags that Meson wants to
use, but doesn't work with our *BSD toolchains.
See https://github.com/mesonbuild/meson/issues/3593
This avoids the double warning
warning: 'ping-store' is a deprecated alias for 'store ping'
warning: 'nix store ping' is a deprecated alias for 'nix store info'
* Only build perl subproject on Linux
* Fix various Windows regressions
* Don't put the emulator hook in test builds
We run the tests in a separate derivation. Only need it for the dev shell.
* Fix native dev shells
* Fix cross dev shells we don't know how to emulate
Co-authored-by: PoweredByPie <poweredbypie@users.noreply.github.com>
Co-authored-by: Joachim Schiele <js@lastlog.de>
Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>
In _very_ rare cases (I had about 7 cases out of 32200 files!),
the order of how inherit-from bindings are printed when using
`nix-instantiate --parse` gets messed up.
The cause of this seems to be because the std::map the bindings are
placed in is keyed on a _pointer_, which then uses an
[implementation-defined strict total order](https://en.cppreference.com/w/cpp/language/operator_comparison#Pointer_total_order).
The fix here is to key the bindings on their displacement instead,
which maintains the same order as they appear in the file.
Unfortunately I wasn't able to make a reproducible test for this in the
source, there's something about the local environment that makes it
unreproducible for me.
However I was able to make a reproducible test in a Nix build on a Nix
version from a very recent master:
nix build github:infinisil/non-det-nix-parsing-repro
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Following what is outlined in #10766 refactor the uds-remote-store such
that the member variables (state) don't live in the store itself but in
the config object.
Additionally, the config object includes a new necessary constructor
that takes a scheme & authority.
Tests are commented out because of linking errors with the current config system.
When there is a new config system we can reenable them.
Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>
This generally gives a better experience with bindings generators,
possibly other tooling.
A possible risk is that some generators may not represent unknown
codes correctly.
Rust bindgen by default generates suitable code:
* a type alias nix_err = c_int
* individual constants for the known enum values
It does _not_ generate a closed type that can only hold the values
that were known at code generation time.
If this proves to be a problem, we could instead split the type:
`typedef int nix_err;` for return values
`enum nix_known_err` for code generation.
This would complicate the interface, so let's not do it unless it
is shown to be needed.
This was accidentally introduced
in f71b4da0b3. We didn't notice this
because the version got interpreted by the daemon as the obsolete "CPU
affinity will follow" field, and being non-zero, it would then read
another integer for the ignored CPU affinity.
The default value for the setting was evaluated by
calling a method on the object _being currently constructed_,
so we were using it before all fields were initialized.
This has been fixed by making the called method static,
and not using the previously used fields at all.
But functionality hasn't changed!
The fields were usually always zero (by chance?) anyway,
meaning the conditional path was always taken.
Thus the current logic has been kept, the code simplified,
and UB removed.
This was found with the helper of UBSan.
Splitting it out immediately answers questions like [this],
without increasing the number of compilation units.
I did consider using boost::hash_combine instead, but it doesn't seem
to be quite as capable, accepting only two arguments.
[this]: https://github.com/NixOS/nix/pull/11113#discussion_r1679991573
Progress towards #10766
I thought that #10768 achieved, but when I went to use this stuff (in
Hydra), turns out it did not. (Those `using FooConfig;` lines were not
working --- they are so finicky!) This PR gets the job done, and adds
some trivial unit tests to make sure I did what I intended.
I had to add add a header to expose `SSHStoreConfig`, after which the
preexisting `ssh-store-config.*` were very confusingly named files, so I
renamed them to `common-ssh-store-config.hh` to match the type defined
therein.
They are not actually part of the store layer, but instead part of the
Nix executable infra (libraries don't need plugins, executables do).
This is part of a larger project of moving all of our legacy settings
infra to libmain, and having the underlying libraries just have plain
configuration structs detached from any settings infra / UI layer.
Progress on #5638
Previous test implementation assumed that grep supports newlines
in patterns. It doesn't, so tests spuriously passed, even though
some tests outputs were broken.
This patches output (and expected output) before grepping,
so there're no newlines in pattern.
This makes it possible to certain discern failures from empty
snippets, which I think is an ok review comment.
Maybe it should do so for swapped column indexes too, but I'm not
sure.
I don't think it matters in the grand scheme. We don't even have
a real use case for `nullopt` now anyway.
Since we don't have a use case, I'm not applying this logic to
higher level functions yet.
Unfortunately these don't render correctly, because they go into the
markdown renderer, instead of the terminal.
```
nix-repl> :doc lib.version
Attribute '[35;1mversion[0m'
… defined at [35;1m/home/user/h/nixpkgs/lib/default.nix:73:40[0m
```
We could switch that to go direct to the terminal, but then we should
do the same for the primops, to get a consistent look.
Reverting for now.
This reverts commit 3413e0338cbee1c7734d5cb614b5325e51815cde.
Got shellcheck passing for misc/systemv/nix-daemon
Not sure how to test this since it's not running on my NixOS machine and
I see no references to it in the directory otherwise.
See #10795
fetchurl can be given a name and url aside from just the url.
Giving a name can be useful if the url has invalid characters such as
tilde for the store.
... at call sites that are may be in the hot path.
I do not know how clever the compiler gets at these sites.
My primary concern is to not regress performance and I am confident
that this achieves it the easy way.
When the separator is empty, no difference is observable.
Note that concatStringsSep has centralized definitions. This adds the
required definitions. Alternatively, `strings-inline.hh` could be
included at call sites.
Considering that `value` was probably parsed with tokenizeString
prior, it's unlikely to contain empty strings, and we have no
reason to remove them either.
Empty attributes are probably not well supported, but the least we
could do is leave a hint.
Attribute path rendering and parsing should be done according to
Nix expression syntax in my opinion.
(System) features are unlikely to be empty strings, but when they
come in through structuredAttrs, they probably can.
I don't think this means we should drop them, but most likely they
will be dropped after this because next time they'll be parsed with
tokenizeString.
TODO: We should forbid empty features.
I don't think it's completely impossible, but I can't construct
one easily as derivationStrict seems to (re)tokenize the outputs
attribute, dropping the empty output.
It's not a scenario we have to account for here.
Bug not reported in 6 years, but here you go.
Also it is safe to switch to normal concatStringsSep behavior
because tokenizeString does not produce empty items.
The empty attribute name should not be dropped from attribute paths.
Rendering attribute paths with concatStringsSep is lossy and wrong,
but this is just a first improvement while dealing with the
dropEmptyInitThenConcatStringsSep problem.
Known behavior changes:
- `MemorySourceAccessor`'s comparison operators no longer forget to
compare the `SourceAccessor` base class.
Progress on #10832
What remains for that issue is hopefully much easier!
- Fix eval cache not being persisted in `nix develop` (since #10570)
- Don't attempt to commit cache transaction if there is no active transaction, which will spew errors in edge cases
- Drive-by: trivial typo fix
On some systems, previous usage of `match` may cause a stackoverflow
(presumably due to the large size of the match result). Avoid this by
(ab)using `replaceStrings` to test for containment without using
regexes, thereby avoiding the issue. The causal configuration seems to
be the stack size hard limit, which e.g. Amazon Linux sets, whereas most
Linux distros leave unlimited.
Match the fn name to similar fn in nixpkgs.lib, but different
implementation that does not use `match`. This impl gives perhaps
unexpected results when the needle is `""`, but the scope of this is
narrow and that case is a bit odd anyway.
This makes for some duplication-of-work as we do a different
`replaceStrings` if this one is true, but this only runs during doc
generation at build time so has no runtime impact.
See https://github.com/NixOS/nix/issues/11085 for details.
Progress on #5638
There are still a global fetcher and eval settings, but they are pushed
down into `libnixcmd`, which is a lot less bad a place for this sort of
thing.
Continuing process pioneered in
52bfccf8d8.
The move assignment was implicitly generated and used in
src/libstore/build/goal.cc:90:22:
90 | this->ex = std::move(*ex);
Clang warns about this generated method being deprecated, so making
them explicit fixes the warning.
It is unclear to me why this worked when not in a VM test, but the
explanation would be in the part of nix-shell we're getting rid of
with the devShell attribute.
When --unpack was used the nix would add the current directory to the
nix store instead of the content of unpacked.
The reason for this is that std::distance already consumes the iterator.
To fix this we re-instantiate the directory iterator in case the
directory only contains a single entry.
This improves the error message of nix-env -qa, among others, which
is crucial for understanding some ofborg eval error reports, such as
https://gist.github.com/GrahamcOfBorg/89101ca9c2c855d288178f1d3c78efef
After this change, it will report the same trace, but also start with
```
error:
… while evaluating the attribute 'devShellTools'
… while evaluating the attribute 'nixos'
… while evaluating the attribute 'docker-tools-nix-shell'
… while evaluating the attribute 'aarch64-darwin'
… from call site
at /home/user/h/nixpkgs/outpaths.nix:48:6:
47| tweak = lib.mapAttrs
48| (name: val:
| ^
49| if name == "recurseForDerivations" then true
<same>
```
The recent fix for CVE-2024-38531 broke the sandbox on macOS
completely. As it’s not practical to use `chroot(2)` on
macOS, the build takes place in the main filesystem tree, and the
world‐unreadable wrapper directory prevents the build from accessing
its `$TMPDIR` at all.
The macOS sandbox probably shouldn’t be treated as any kind of a
security boundary in its current state, but this specific vulnerability
wasn’t possible to exploit on macOS anyway, as creating `set{u,g}id`
binaries is blocked by sandbox policy.
Locking down the build sandbox further may be a good idea in future,
but it already has significant compatibility issues. For now, restore
the previous status quo on macOS.
Thanks to @alois31 for helping me come to a better understanding of
the vulnerability.
Fixes: 1d3696f0fbCloses: #11002
- use the iterator in `CanonPath` to count `level`
- use the `CanonPath::basename` method
- use `CanonPath::root` instead of `CanonPath{""}`
- remove `Path` and `PathView`, use `std::filesystem::path` directly
move together all syntactic and semantic information into one
page, and add a page on data types, which in turn links to the syntax and
semantics.
also split out the note on scoping rules into its own page.
Co-authored-by: Ryan Hendrickson <ryan.hendrickson@alum.mit.edu>
Inspired by
010ff57ebb
From the original PR:
> We do not have any of these warnings appearing at the moment, but
> it seems like a good idea to enable [[nodiscard]] checking anyway.
> Once we start introducing more functions with must-use conditions we will
> need such checking, and the rust stdlib has proven them very useful.
GitHub Actions seems to have magically switched architectures
without changing their identifiers.
See 2813ee66cb/README.md (available-images)
Maybe they have more complete documentation elsewhere, but it
seems to be incapable of selecting a runner based on architecture.
* doc: fix `directory` definition in nix-archive.md
Before the change the document implied that directory of a single entry
contained entry:
"type" "directory" "type" directory" "entry" ...
After the change document should expand into:
"type" "directory" "entry" ...
Co-authored-by: John Ericson <git@JohnEricson.me>
The code that counts the number of elided attrs incorrectly used the
per-printer "global" attribute counter instead of a counter that
was relevant only to the current attribute set.
This bug flew under the radar because often the attribute sets aren't
nested, not big enough, or we wouldn't pay attention to the numbers.
I've noticed the issue because the difference underflowed.
Although this behavior is tested by the functional test
lang/eval-fail-bad-string-interpolation-4.nix, the underflow slipped
through review. A simpler reproducer would be as follows, but I
haven't added it to the test suite to keep it simple and marginally
faster.
```
$ nix run nix/2.23.1 -- eval --expr '"" + (let v = { a = { a = 1; b = 2; c = 1; d = 1; e = 1; f = 1; g = 1; h = 1; }; b = { a = 1; b = 1; c = 1; }; }; in builtins.deepSeq v v)'
error:
… while evaluating a path segment
at «string»:1:6:
1| "" + (let v = { a = { a = 1; b = 2; c = 1; d = 1; e = 1; f = 1; g = 1; h = 1; }; b = { a = 1; b = 1; c = 1; }; }; in builtins.deepSeq v v)
| ^
error: cannot coerce a set to a string: { a = { a = 1; b = 2; c = 1; d = 1; e = 1; f = 1; g = 1; h = 1; }; b = { a = 1; «4294967289 attributes elided» }; }
```
* string interpolation escape example
Make it easier to find the documentation, and the example might be enough for most cases.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
We don't apply any patches to it, and vendoring it locks users into
bugs (it hasn't been updated since its introduction in late 2021).
Closes https://git.lix.systems/lix-project/lix/issues/164
Change-Id: Ied071c841fc30b0dfb575151afd1e7f66970fdb9
(cherry picked from commit 80405d06264f0de1c16ee2646388ab501df20628)
On one hand, new things should be formatted. On the other, we just
bacported this file to many prior branches, and if we need to make
changes to it and backport them also, formatting the file on master but
not the release branches would cause issues.
We're building a bit of Darwin meson indirectly through `checks`,
but it'd be annoying to encounter broken un-`check`-ed stuff
during the porting process, so let's just do the right thing now.
This avoids polluting nixComponents with things that aren't our
components.
Fixes the extraction of passthru tests, which failed for boehmgc
which had many irrelevant ones anyway.
flatMapAttrs is easier to read because it introduces the values
before using them, kind of like a `let` bindings with multiple
values.
The repeated comments remind the reader of the purpose of the
innermost attrsets, which is actually very simple.
Knowing that they go right into the result should help a lot
with building a mental model for this pattern.
It was added above this conditional
Worker::Worker(LocalStore & store)
: store(store)
{
/* Debugging: prevent recursive workers. */
if (working) abort();
working = true;
However, `working` has since been removed.
Source: 7f8e805c8e/src/libstore/build.cc (L2617)
The old `std::variant` is bad because we aren't adding a new case to
`FileIngestionMethod` so much as we are defining a separate concept ---
store object content addressing rather than file system object content
addressing. As such, it is more correct to just create a fresh
enumeration.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This tests the parser and JSON format using the DRV files from the tests
added in the previous commit.
Co-Authored-By: John Ericson <John.Ericson@Obsidian.Systems>
This tests the Nix language side of things.
We are purposely skipping most of `common.sh` because it is overkill for
this test: we don't want to have an "overfit" test environment.
Co-Authored-By: John Ericson <John.Ericson@Obsidian.Systems>
Previously, the .chroot directory had permission 750 or 755 (depending
on the uid-range system feature) and was owned by root/nixbld. This
makes it possible for any nixbld user (if uid-range is disabled) or
any user (if uid-range is enabled) to inspect the contents of the
chroot of an active build and maybe interfere with it (e.g. via /tmp
in the chroot, which has 1777 permission).
To prevent this, the root is now a subdirectory of .chroot, which has
permission 700 and is owned by root/root.
Instead of running the builds under
`$TMPDIR/{unique-build-directory-owned-by-the-build-user}`, run them
under `$TMPDIR/{unique-build-directory-owned-by-the-daemon}/{subdir-owned-by-the-build-user}`
where the build directory is only readable and traversable by the daemon user.
This achieves two things:
1. It prevents builders from making their build directory world-readable
(or even writeable), which would allow the outside world to interact
with them.
2. It prevents external processes running as the build user (either
because that somehow leaked, maybe as a consequence of 1., or because
`build-users` isn't in use) from gaining access to the build
directory.
the `std::filesystem::create_directories` can fail due to insufficient
permissions. We convert this error into a `SysError` and catch it
wherever required.
#2230 broadened the scope of macOS hardlink exclusion but did not change the comments. This was a little confusing for me, so I figured the comments should be updated.
This will avoid some out-of-memory issues in GitHub actions that result
from num jobs > 1 and num cores = 4. Once we only have the Meson build
system, this problem should go away, and we can reenable these jobs.
The documentation is clear about the supported formats (with at least
`builtins.fetchTarball`). The way the code was written previously it
supported all the formats that libarchive supported. That is a
surprisingly large amount of formats that are likely not on the radar
of the Nix developers and users. Before people end up relying on
this (or if they do) it is better to break it now before it becomes a
widespread "feature".
Zip file support has been retained as (at least to my knowledge)
historically that has been used to fetch nixpkgs in some shell
expressions *many* years back.
Fixes https://github.com/NixOS/nix/issues/10917
I hope this will make it easier to maintain, and also make it easier for
others to assist with porting the rest of the build system to Meson.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Previously (in cfc18a7739), we forgot to
compare the algo at all. This means we keep the same ordering as before
by making the stuff we always have compared take priority.
The idea is two-fold:
- Replace autotools with Meson
- Build each library in its own derivation
The interaction of these two features is that Meson's "subprojects"
feature (https://mesonbuild.com/Subprojects) allows us to have single
dev shell for building all libraries still, while also building things
separately. This allows us to break up the build without a huge
productivity lost.
I tested the Linux native build, and NetBSD and Windows cross builds.
Also do some clean ups of the Flake in the process of supporting new
jobs.
Special thanks to everyone that has worked on a Meson port so far,
@p01arst0rm and @Qyriad in particular.
Co-Authored-By: p01arst0rm <polar@ever3st.com>
Co-Authored-By: Artemis Tosini <lix@artem.ist>
Co-Authored-By: Artemis Tosini <me@artem.ist>
Co-Authored-By: Felix Uhl <felix.uhl@outlook.com>
Co-Authored-By: Jade Lovelace <lix@jade.fyi>
Co-Authored-By: Lunaphied <lunaphied@lunaphied.me>
Co-Authored-By: Maximilian Bosch <maximilian@mbosch.me>
Co-Authored-By: Pierre Bourdon <delroth@gmail.com>
Co-Authored-By: Qyriad <qyriad@qyriad.me>
Co-Authored-By: Rebecca Turner <rbt@sent.as>
Co-Authored-By: Winter <winter@winter.cafe>
Co-Authored-By: eldritch horrors <pennae@lix.systems>
Co-Authored-By: jade <lix@jade.fyi>
Co-Authored-By: julia <midnight@trainwit.ch>
Co-Authored-By: rebecca “wiggles” turner <rbt@sent.as>
Co-Authored-By: wiggles dog <rbt@sent.as>
Co-Authored-By: fricklerhandwerk <valentin@fricklerhandwerk.de>
Co-authored-By: Eli Schwartz <eschwartz93@gmail.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This is not really part of the evaluator: it is just an integration
between Boehm GC and Boost coroutines usable for any purpose. The
evaluator (merely) optionally uses it.
Since 24.05 (I think) we need to pass `-c` or Clang thinks we want to
compile *both* a final executable and precompiled header file, and
complains that we cannot use `-o` with multiple outputs. `-c` seems fine
with GCC too, so I just put it in there conditionally.
the thesis is still the defining document with all the motivation and
explanations.
adding it here for greater visibility.
also more emphasis and clarity around the community aspect.
the hydra build job seems a bit arbitrary right there. may be better for
the contributing guide.
The implementation of `nix::createDirs` allows it to be a simple wrapper
around `std::filesystem::create_directories` as its return value is not
used anywhere.
throwing exceptions is fine, but throwing exceptions during exception
handling is hard enough to do correctly that we should just forbid it
entirely out of an overabundance of caution. in cases where terminate
is the correct answer the users of Finally must call it manually now.
Source: 6c777476c9
In most real world cases, the Link header is set on the redirect, not on
the final file. This regressed in Lix earlier and while new unit tests
were added to cover it, this integration test should probably have also
caught it.
Source: a3256a9375
* docs: fix python nix-shell example
This Python code snippet depended on Python 2 which has been marked as insecure in 24.05.
I modernized the example so new users will not be surprised upon copying and pasting the snippet for exploration.
Co-authored-by: John Ericson <git@JohnEricson.me>
Before, `-lnixutil` was just stuck in `nix-store.pc`, but that doesn't
seem so nice.
This prepares us to distribute `libnixutil` in a separate package if we
want, but it should be a good change either way. I suspect it wasn't
done before because libutil was an extra unstable interface, but I don't
think we need worry about that. *All* the C++ is less stable than the C
(or that's the goal at least).
For what it's worth, Lix also created this pkg-config file *en passant*
during their rename:
c97e17144e (diff-3c4f60cc44a0e35444c7f45331cfa50f76637118)
This re-enables support for older bwdgc versions without complicating
the code too much.
Coroutines generally only interfere with GC during source filtering,
so it's not too bad of a regression on older bdwgc.
This seems preferable over conditional compilation to enable the patch
etc; we've already spent a lot of complexity budget on this GC-coroutine
interaction...
Manually tested by printing to stderr in both branches (sp in os
stack, or not), and triggering a GC in a filterSource function,
e.g.:
let
generateTree = n: if n == 0 then "ha" else { left = generateTree (n - 1); right = generateTree (n - 1); };
in
builtins.deepSeq (generateTree 18) ...
Note that the darwin still uses the strategy of disabling GC, despite
having an implementation that compiles. The proper solution will be
enabled and tested later.
... so that we may perhaps later extend the interface.
Note that Nixpkgs' lib.warn already requires a string coercible
argument, so this is reasonable. Also note that string coercible
values aren't all strings, but in practice, for warn, they are.
Progress on #10832
This doesn't switch to auto-deriving the fields, but by defining `<=>`
we allow deriving `<=>` in downstream types where `Hash` is used.
Fixes assertion failure if outputsToInstall is empty by defaulting to the "out"
output. That is, behavior between the following commands should be consistent:
$ nix build --no-link --json .#nothing-to-install-no-out
error: derivation '/nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-nothing-to-install-no-out.drv' does not have wanted outputs 'out'
$ nix build --no-link --file default.nix --json nothing-to-install-no-out
error: derivation '/nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-nothing-to-install-no-out.drv' does not have wanted outputs 'out'
Real-world example of this issue:
$ nix build --json .#.legacyPackages.aarch64-linux.texlive.pkgs.iwona
error: derivation '/nix/store/dj0h6b0pnlnan5nidnhqa0bmzq4rv6sx-iwona-0.995b.drv' does not have wanted outputs 'out'
$ git rev-parse HEAD
eee33247cf6941daea8398c976bd2dda7962b125
$ nix build --json --file . texlive.pkgs.iwona
nix: src/libstore/outputs-spec.hh:46: nix::OutputsSpec::Names::Names(std::set<std::__cxx11::basic_string<char> >&&): Assertion `!empty()' failed.
Aborted (core dumped)
1. Fix build by making the legacy SSH Storey's secret `logFD` setting
not a setting on Windows. (It doesn't make sense to specify `void *`
handles by integer cross-proccess, I don't think.)
2. Move some files that don't need to be Unix-only anymore back to their
original locations.
Before:
$ nix flake lock --override-input nixpkgs gitlab:simple-nixos-mailserver/nixos-mailserver/nonexistent
fetching git input 'git+file:///home/linus/projects/lix'
fetching gitlab input 'gitlab:simple-nixos-mailserver/nixos-mailserver/nonexistent'
error: [json.exception.type_error.302] type must be string, but is null
After:
/tmp/inst/bin/nix flake lock --override-input nixpkgs gitlab:simple-nixos-mailserver/nixos-mailserver/nonexistent
warning: unknown experimental feature 'repl-flake'
error:
… while updating the lock file of flake 'git+file:///home/joerg/git/nix?ref=refs/heads/master&rev=62693c2c37c8edd92f95114eb1387b461fc671df'
… while updating the flake input 'nixpkgs'
… while fetching the input 'gitlab:simple-nixos-mailserver/nixos-mailserver/nonexistent'
error: No commits returned by GitLab API -- does the git ref really exist?
Adapted from: 3df013597d
This turns errors like:
error: flake output attribute 'hydraJobs' is not a derivation or path
into errors like:
error: expected flake output attribute 'hydraJobs' to be a derivation or
path but found a set: { binaryTarball = «thunk»; build = «thunk»; etc> }
This change affects all InstallableFlake commands.
Source: 20981461d4
Signed-off-by: Jörg Thalheim <joerg@thalheim.io>
* docs: mention importNative/exec in allow-unsafe-native-code-during-evaluation
Both of these still needs their own actual documentation, but they are
at least now mentioned that they exist and what they're enabled by.
Co-authored-by: Qyriad <qyriad@qyriad.me>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
- Get a rump derivation goal: hook instance will come later, local
derivation goal will come after that.
- Start cleaning up the channel / waiting code with an abstraction.
By moving `host` to the config, we can do a lot further cleanups and
dedups. This anticipates a world where we always go `StoreReference` ->
`*StoreConfig` -> `Store*` rather than skipping the middle step too.
Progress on #10766
Progress on https://github.com/NixOS/hydra/issues/1164
This increases test coverage, and gets the worker protocol ready to be
used by Hydra.
Why don't we just try to use the store interface in Hydra? Well, the
problem is that the store interface works on connection pools, with each
opreation getting potentially a different connection, but the way temp
roots work requires that we keep one logical "transaction" (temp root
session) using the same connection.
The longer-term solution probably is making connections themselves
implement the store interface, but that is something that builds on
this, so I feel OK that this is not churn in the wrong direction.
Fixes#9584
We don't want to rely on how C assigns numbers for enums in the wire
format. Sure, this is totally determined by the ABI, but it obscures the
code and makes it harder to safely change the enum definition (should we
need to) without accidentally breaking the wire format.
Do this instead of an unchecked cast
I redid this to use the serialisation framework (including a unit test),
but I am keeping the reference to credit Jade for spotting the issue.
Change-Id: Icf6af7935e8f139bef36b40ad475e973aa48855c
(adapted from commit 2a7a824d83dc5fb33326b8b89625685f283a743b)
Co-Authored-By: Jade Lovelace <lix@jade.fyi>
File not found while importing is not currently caught by the tab-completion handler.
Original bug report: https://git.lix.systems/lix-project/lix/issues/340
Fix has been adapted from https://gerrit.lix.systems/c/lix/+/1189
Example crash:
$ cat /tmp/foo.nix
{
someImport = import ./this_file_does_not_exist;
}
$ ./src/nix/nix repl --file /tmp/foo.nix
warning: unknown experimental feature 'repl-flake'
Nix 2.23.0pre20240517_dirty
Type :? for help.
Loading installable ''...
Added 1 variables.
nix-repl> someImport.<TAB>
This way we can commit the same amount of stack size (64 MB) without a conditional.
Includes nix, libnixexpr-tests, libnixfetchers-tests, libnixstore-tests, libnixutil-tests.
https://github.com/NixOS/nix/pull/10555 added a check requiring
that output parameters always have an uninitialized Value as argument.
Unfortunately the output parameter of the primop callback received
a thunk instead.
See the comment for implementation considerations.
This was accidentally removed in
e989c83b44. I restored it and also did a
few other cleanups:
- Make a static method for namespacing purposes
- Put the test files in the data dir with the other test data
- Avoid mutating globals in the machine config tests
This will be used by Hydra.
* reword documentation on `nix-copy-closure`
- one sentence per line
- be more precise with respect to which Nix stores are being accessed
- make a clear distinction between store paths and store objects
- add links to definitions of terms
- clarify which machine is which
- --to and --from don't take arguments
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
In particular `local://<path>` and `unix://` (without any path) now
work, and mean the same things as `local` and `daemon`, respectively. We
thus now have the opportunity to desguar `local` and `daemon` early.
This will allow me to make a change to
https://github.com/NixOS/nix/pull/9839 requested during review to
desugar those earlier.
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
1. Hydra currently queries for multiple path infos at once, so let us
make a connection item for that.
2. The minimum of the two versions should always be used, see #9584.
(The issue remains open because the daemon protocol needs to be
likewise updated.)
The JSON format no longer uses the legacy ATerm `r:` prefixing nonsese,
but separate fields.
Progress on #9866
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
- add links to definitions of terms
- one sentence per line
- be more specific about which store is used for the import
- clearly distinguish store paths and store objects
- make a recommendation to use `nix-copy-closure` for efficient SSH transfers
Basically I'd expect the same behavior as with `nix-build`, i.e.
with `--keep-going` the hash-mismatch error of each failing
fixed-output derivation is shown.
The approach is derived from `Store::buildPaths` (`entry-point.cc`):
instead of throwing the first build-result, check if there are any build
errors and if so, display all of them and throw after that.
Unfortunately, the BuildResult struct doesn't have an `ErrorInfo`
(there's a FIXME for that at least), so I have to construct my own here.
This is a rather cheap bugfix and I decided against touching too many
parts of libstore for that (also I don't know if that's in line with the
ongoing refactoring work).
Closes https://git.lix.systems/lix-project/lix/issues/302
Change-Id: I378ab984fa271e6808c6897c45e0f070eb4c6fac
Signed-off-by: Jörg Thalheim <joerg@thalheim.io>
On several occasions I've found myself confused when trying to delete
a store path, because I am told it's still alive, but
nix-store --query --roots doesn't show anything. Let's save future
users this confusion by mentioning that a path might be alive due to
having referrers, not just roots.
given `nix-copy-closure` exists, it doesn't make much sense to do
nix-store --export $paths | nix-store --import --store ssh://foo@bar
since that dumps everything rather than granularly transferring store
objects as needed.
therefore, pick an example where dumping the entire closure into a file
actually makes a difference, such as when deploying to airgapped systems.
In addition:
- Take the opportunity to add a bunch more missing hyperlinks, too.
- Remove some glossary entries that are now subsumed by dedicated pages.
We used to not be able to do this without breaking link fragments, but
now we can, so pick up where we left off.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
- add links to definitions of terms
- one sentence per line
- be more specific about which store is used for the import
- clearly distinguish store paths and store objects
- make a recommendation to use `nix-copy-closure` for efficient SSH transfers
the individual commands' documentation should provide enough examples to
make sense of the options and judge what to use and when. proper guides,
which would require a more elaborate setup to show off Nix's
capabilities are out of scope for the reference manual.
* doc: convention improvements for copying closure
use -P, which only considers executables but not shell builtins
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
previously the test directory could have been left untouched before executing
a test when `init.sh` was not run - and sometimes it isn't
supposed to be run - which made the test suite highly stateful and thus
behaving surprisingly on multiple runs.
pararameterisation is not actually needed the way things are currently
set up, and it confused me when trying to understand what the code does.
all but one test sources vars-and-functions.sh, which nominally only
defines variables, but in practice is always coupled with the actual
initialisation. while the cleaner way of making this more legible would
be to source variables and initialisation separately, this would produce
a huge diff.
the change requires a few small fixes to keep the tests working:
- only create test home directory during initialisation
that vars-and-functions.sh wrote to the file system seems not write
- fix creation of the test directory
due to statefulness, the test home directory was implicitly creating
the test root, too. decoupling that made it apparent that this was
probably not intentional, and certainly confusing.
- only source vars-and-functions.sh if init.sh is not needed
there is one test case that only needs a helper function but no
initialisation side effects
- remove some unnecessary cleanups and split parts of re-used test code
there were confusing bits in how initialisation code was repurposed,
which break if trying to refactor the outer layers naively...
This is useful for diagnosing whether an evaluation is copying large
paths to the store. Example:
$ nix build .#packages.x86_64-linux.default --large-path-warning-threshold 1000000
warning: copied large path '/home/eelco/Dev/nix-master/' to the store (6271792 bytes)
warning: copied large path '«github:NixOS/nixpkgs/b550fe4b4776908ac2a861124307045f8e717c8e?narHash=sha256-7kkJQd4rZ%2BvFrzWu8sTRtta5D1kBG0LSRYAfhtmMlSo%3D»/' to the store (155263768 bytes)
warning: copied large path '«github:libgit2/libgit2/45fd9ed7ae1a9b74b957ef4f337bc3c8b3df01b5?narHash=sha256-oX4Z3S9WtJlwvj0uH9HlYcWv%2Bx1hqp8mhXl7HsLu2f0%3D»/' to the store (22175416 bytes)
warning: copied large path '/nix/store/z985088mcd6w23qwdlirsinnyzayagki-source' to the store (5885872 bytes)
This fixes https://github.com/NixOS/nixpkgs/pull/290775 by not expanding aliases
when sourcing the stdenv setup script. The way bash handles aliases is to expand
them when a function is defined, not when it is used. I.e.:
$ alias echo="echo bar "
$ echo foo
bar foo
$ xyzzy() { echo foo; }
$ shopt -u expand_aliases
$ xyzzy
bar foo
$ xyzzy2() { echo foo; }
$ xyzzy2
foo
The problem is that ~/.bashrc is sourced before the stdenv setup, and bashrc
commonly sets aliases for ‘cp’, ‘mv’ and ‘rm’ which you don’t want to take
effect in the stdenv derivation builders. The original commit introducing this
feature (5fd8cf7667) even mentioned this very
alias.
The only way to avoid this is to disable aliases entirely while sourcing the
stdenv setup, and reenable them afterwards.
Passing the commit message as an argument causes update failures on repositories with lots of flake inputs. In some cases, the commit message is over 250,000 bytes.
the old `copyFile` was just a wrapper that was calling the `copy`
function. This wrapper function is removed and the `copy` function is
renamed to `copyFile`.
Building derivations is a lot harder, but the downloading goals is
portable enough.
The "common channel" code is due to Volth. I wonder if there is a way we
can factor it out into separate functions / files to avoid some
within-function CPP.
Co-authored-by: volth <volth@volth.com>
The warning was done to handle older Nix releases that didn't have
Docker images (091f232896), but this was
a bad idea because it causes us to silently skip uploading Docker
images if e.g. Hydra hasn't finished building them yet.
Issue #10648.
In streaming mode, libarchive doesn't handle symlinks in zip files
correctly. So write the entire file to disk so libarchive can access
it in random-access mode.
Fixes#10649. This was broken in cabee98152.
builtins.strictDerivation returns an attribute set with drvPath and
output paths. For some reason, current implementation forbids drv
instead of drvPath.
Remove `isLink` in favor of `std::filesystem::is_link`
This is one step closer to eventually getting rid of most of our file system utils (in `file-system.cc`) in favor of the `std::filesystem`.
- specify meeting times in terms of a time zone rather than standard
time (the first encompasses standard time changes)
- add information on who can participate and how
- unrelated but still important: add GitHub handle to contact the team
Sometimes we read a directory with children we cannot stat. It's a pitty
we even try to stat at all (wasteful) in the `DT_UNKNOWN` case, but at
least this should get rid of the failure.
This was changed in #10611, which caused the derivation paths of
anything using builtin:fetchurl to change (i.e. all of
Nixpkgs). However, impureEnvVars doesn't actually do anything for
builtin:fetchurl, so we can just set it to its historical value.
This makes for shorter and more portable code.
The only tricky part is catching exceptions: I just searched for near by
`catch (Error &)` or `catch (SysError &)` and adjusted them to `catch
(std::filesystem::filesystem_error &)` according to my human judgement.
Good for windows portability; will help @siddhantk232 with his GSOC
project.
Different parts of the project honor different sets of proxy environment
variables. With this commit all parts of the project will honor the same
set of proxy environment variables.
---------
Co-authored-by: Your Name <you@example.com>
Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>
Now that SourcePath uses a SourceAccessor instead of an InputAccessor,
we can use it in function signatures instead of passing a
SourceAccessor and CanonPath separately.
Make sure that `extraSandboxProfile` is set before we check whether it's
empty or not (in the `sandbox=true` case).
Also adds a test case for this.
Co-Authored-By: Artemis Tosini <lix@artem.ist>
Co-Authored-By: Eelco Dolstra <edolstra@gmail.com>
After the removal of the InputAccessor::fetchToStore() method, the
only remaining functionality in InputAccessor was `fingerprint` and
`getLastModified()`, and there is no reason to keep those in a
separate class.
Fix formatting violations, update blacklist to reflect moved files.
PR #10556 passed CI before the new formating rules were added, and our
CI has the race condition of allowing old results, resulting in master
getting broken.
This missing GC root wasn't much of a problem before, because the
heap would end up with a reference to the `baseEnv` pretty soon,
but when unit testing, the construction of `EvalState` doesn't
necessarily happen well before GC runs for the first time.
Found while unit testing the Rust bindings that currently reside
at https://github.com/nixops4/nixops4/tree/main/rust
When trying the „nix-store info“ commands on this page I received the error "error: 'info' is not a recognised command". According to https://github.com/NixOS/nix/issues/9349 info seems to have been an alias for ping. So why not just replace info with ping?
This makes it match the current pattern:
- `package.nix` assumes deps are right version
- Overlay in `flake.nix` creates `*-nix` package variations
- Overlay manually passes in those packages to `package.nix`
* move single-user uninstall to the end
this is not the default method of installation, and therefore irrelevant
for most users.
* move the backup restore instructions to the first step
for most users we can expect that the system-wide shell init files were
not ever touched, so we can as well tell them to do the most likely
thing.
from experience, while it's not necessarily safe to just mess with these
files, most people are simply confused by the complexity of
instructions.
* provide more detailed instructions for using `sudo vifs`
we can expect most beginners not to ever have used `vi`, and they will
probably need some hand-holding.
* express instructions as a script
Co-authored-by: wamirez <wamirez@protonmail.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Closes#10585
As it turns out, libseccomp maintains an internal syscall table and
validates each rule against it. This means that when using libseccomp
2.5.4 or older, one may pass `452` as syscall number against it, but
since it doesn't exist in the internal structure, `libseccomp` will refuse
to create a filter for that. This happens with nixpkgs-23.11, i.e. on
stable NixOS and when building Nix against the project's flake.
To work around that
* a backport of libseccomp 2.5.5 on upstream nixpkgs has been
scheduled[1].
* the package now uses libseccomp 2.5.5 on its own already. This is to
provide a quick fix since the correct fix for 23.11 is still a staging cycle
away.
It must not be possible to build a Nix with an incompatible libseccomp
version (nothing can be built in a sandbox on Linux!), so configure.ac
rejects libseccomp if `__SNR_fchmodat2` is not defined.
We still need the compat header though since `SCMP_SYS(fchmodat2)`
internally transforms this into `__SNR_fchmodat2` which points to
`__NR_fchmodat2` from glibc 2.39, so it wouldn't build on glibc 2.38.
The updated syscall table from libseccomp 2.5.5 is NOT used for that
step, but used later, so we need both, our compat header and their
syscall table 🤷
[1] https://github.com/NixOS/nixpkgs/pull/306070
Add a method to check if a value has been initialized. This helps avoid
segfaults when calling `type()`.
Useful in the context of the new C API.
Closes#10524
I've added the new local.mk to the package sources. While this
should not be needed for the build, it is the simplest solution,
and won't cause many extra rebuilds, because the file won't change
very often.
This reverts commit 62feb5ca09263c78ddb692836228223e5b58d3ae.
It runs as part of the functional tests, which control the environment,
solving some of the problems a default config has when run in the
sandbox.
Windows now has some basic Unix Domain Socket support, see
https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/
Building `nix daemon` on Windows I've left for later, because the daemon
currently forks per connection but this is not an option on Windows. But
we can get the client part working right away.
With Linux kernel >=6.6 & glibc 2.39 a `fchmodat2(2)` is available that
isn't filtered away by the libseccomp sandbox.
Being able to use this to bypass that restriction has surprising results
for some builds such as lxc[1]:
> With kernel ≥6.6 and glibc 2.39, lxc's install phase uses fchmodat2,
> which slips through 9b88e52846/src/libstore/build/local-derivation-goal.cc (L1650-L1663).
> The fixupPhase then uses fchmodat, which fails.
> With older kernel or glibc, setting the suid bit fails in the
> install phase, which is not treated as fatal, and then the
> fixup phase does not try to set it again.
Please note that there are still ways to bypass this sandbox[2] and this is
mostly a fix for the breaking builds.
This change works by creating a syscall filter for the `fchmodat2`
syscall (number 452 on most systems). The problem is that glibc 2.39
and seccomp 2.5.5 are needed to have the correct syscall number available
via `__NR_fchmodat2` / `__SNR_fchmodat2`, but this flake is still on
nixpkgs 23.11. To have this change everywhere and not dependent on the
glibc this package is built against, I added a header
"fchmodat2-compat.hh" that sets the syscall number based on the
architecture. On most platforms its 452 according to glibc with a few
exceptions:
$ rg --pcre2 'define __NR_fchmodat2 (?!452)'
sysdeps/unix/sysv/linux/x86_64/x32/arch-syscall.h
58:#define __NR_fchmodat2 1073742276
sysdeps/unix/sysv/linux/mips/mips64/n32/arch-syscall.h
67:#define __NR_fchmodat2 6452
sysdeps/unix/sysv/linux/mips/mips64/n64/arch-syscall.h
62:#define __NR_fchmodat2 5452
sysdeps/unix/sysv/linux/mips/mips32/arch-syscall.h
70:#define __NR_fchmodat2 4452
sysdeps/unix/sysv/linux/alpha/arch-syscall.h
59:#define __NR_fchmodat2 562
I tested the change by adding the diff below as patch to
`pkgs/tools/package-management/nix/common.nix` & then built a VM from
the following config using my dirty nixpkgs master:
{
vm = { pkgs, ... }: {
virtualisation.writableStore = true;
virtualisation.memorySize = 8192;
virtualisation.diskSize = 12 * 1024;
nix.package = pkgs.nixVersions.nix_2_21;
};
}
The original issue can be triggered via
nix build -L github:nixos/nixpkgs/d6dc19adbda4fd92fe9a332327a8113eaa843894#lxc \
--extra-experimental-features 'nix-command flakes'
however the problem disappears with this patch applied.
Closes#10424
[1] https://github.com/NixOS/nixpkgs/issues/300635#issuecomment-2031073804
[2] https://github.com/NixOS/nixpkgs/issues/300635#issuecomment-2030844251
With Nix 2.3, it was possible to pass a subpath of a store path to
exportReferencesGraph:
with import <nixpkgs> {};
let
hello = writeShellScriptBin "hello" ''
echo ${toString builtins.currentTime}
'';
in
writeClosure [ "${hello}/bin/hello" ]
This regressed with Nix 2.4, with a very confusing error message, that
presumably indicates it was unintentional:
error: path '/nix/store/3gl7kgjr4pwf03f0x70dgx9ln3bhl7zc-hello/bin/hello' is not in the Nix store
At this point many features are stripped out, but this works:
- Can run libnix{util,store,expr} unit tests
- Can run some Nix commands
Co-Authored-By volth <volth@volth.com>
Co-Authored-By Brian McKenna <brian@brianmckenna.org>
local.mk:5: warning: overriding recipe for target 'outputs/dev/include/nix/nix_api_expr.h'
local.mk:5: warning: ignoring old recipe for target 'outputs/dev/include/nix/nix_api_expr.h'
local.mk:5: warning: overriding recipe for target 'outputs/dev/include/nix/nix_api_external.h'
local.mk:5: warning: ignoring old recipe for target 'outputs/dev/include/nix/nix_api_external.h'
local.mk:5: warning: overriding recipe for target 'outputs/dev/include/nix/nix_api_value.h'
local.mk:5: warning: ignoring old recipe for target 'outputs/dev/include/nix/nix_api_value.h'
local.mk:5: warning: overriding recipe for target 'outputs/dev/include/nix/nix_api_store.h'
local.mk:5: warning: ignoring old recipe for target 'outputs/dev/include/nix/nix_api_store.h'
local.mk:5: warning: overriding recipe for target 'outputs/dev/include/nix/nix_api_util.h'
local.mk:5: warning: ignoring old recipe for target 'outputs/dev/include/nix/nix_api_util.h'
This also reworks the Mercurial fetcher (which was still using the
old cache interface) to have two distinct cache mappings:
* A ref-to-rev mapping, which is store-independent.
* A rev-to-store-path mapping.
Code operating on store objects (including creating them) should, in
general, use `ContentAddressMethod` rather than `FileIngestionMethod`.
See also dfc876531f which included some
similar refactors.
See https://github.com/NixOS/nix/pull/8699#discussion_r1554312181
Casting a function pointer to `void*` is undefined behavior in the C
spec, since there are platforms with different sizes for these two kinds
of pointers. A safe alternative might be `void (*callback)()`
https://github.com/NixOS/nix/pull/10456 fixed the addition of symlink
store paths to the sandbox, but also made it so that the hardcoded
sandbox paths (like `/etc/hosts`) were now bind-mounted without
following the possible symlinks. This made these files unreadable if
there were symlinks (because the sandbox would now contain a symlink to
an unreachable file rather than the underlying file).
In particular, this broke FOD derivations on NixOS as `/etc/hosts` is a
symlink there.
Fix that by canonicalizing all these hardcoded sandbox paths before
adding them to the sandbox.
Like always declining; local builds only, as can be inferred from the
docs. (Not worth spending too many words on this pretty obvious
behavior, I think. Also, plans to remove it? https://github.com/NixOS/nix/issues/1221)
This requires moving resolveSymlinks() into SourceAccessor. Also, it
requires LocalStoreAccessor::maybeLstat() to work on parents of the
store (to avoid an error like "/nix is not in the store").
Fixes#10375.
Instead of relying on setup script to set output variables when
structured attributes are enabled, iterate over the values of an
outputs associative array.
See also
374fa3532e/pkgs/stdenv/generic/setup.sh (L23-L26)
Bind-mounting symlinks is apparently not possible, which is why the
thing was failing.
Fortunately, symlinks are small, so we can fallback to copy them at no cost.
Fix https://github.com/NixOS/nix/issues/9579
Co-authored-by: Artturin <Artturin@artturin.com>
Now that we have a few things identifying content address methods by
name, we should be consistent about it.
Move up the `parseHashAlgoOpt` for tidiness too.
Discussed this change for consistency's sake as part of #8876
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
This requires `--substitute-on-destination` if you want the remote side
to substitute instead of copying if possible.
For completeness sake, document it here.
Also, the stable Nix from nixpkgs is still 2.18, so more folks may
stumble upon this when this is bumped, so I'd expect this to be actually
useful.
Closes#10182
This was used in only one place, namely builtins.fetchurl with an
expected hash. Since this can cause similar issues as described
in #9814 and #9905 with the "locked" flag for fetchTarball and fetchTree,
let's just remove it.
Note that if an expected hash is given and the hash algorithm is
SHA-256, then we will never do a download anyway if the resulting
store path already exists. So removing the "locked" flag will only
cause potentially unnecessary HTTP requests (subject to the tarball
TTL) for non-SHA-256 hashes.
This probably snuck in in a refactor using truthiness or so. The
trustedness flag was having the optional fullness checked, rather than
the actual contained trust level.
Also adds some tests.
```
m1@6876551b-255d-4cb0-af02-8a4f17b27e2e ~ % nix store ping
warning: 'nix store ping' is a deprecated alias for 'nix store info'
Store URL: daemon
Version: 2.20.4
Trusted: 0
m1@6876551b-255d-4cb0-af02-8a4f17b27e2e ~ % nix doctor
warning: 'doctor' is a deprecated alias for 'config check'
[PASS] PATH contains only one nix version.
[PASS] All profiles are gcroots.
[PASS] Client protocol matches store protocol.
[INFO] You are trusted by store uri: daemon
```
The script at `/nix/store/...-nix-2.21.0/etc/profile.d/nix-daemon.sh` was leaving behind a variable, which was visible in the user's shell environment, but not used outside the script.
code blocks, if not surrounded by empty lines, have the language
tags (in these cases, always `nix`) show up in the output of :doc.
for example:
nix-repl> :doc builtins.parseFlakeRef
Synopsis: builtins.parseFlakeRef flake-ref
Parse a flake reference, and return its exploded form.
For example: nix builtins.parseFlakeRef
"github:NixOS/nixpkgs/23.05?dir=lib" evaluates to: nix { dir =
"lib"; owner = "NixOS"; ref = "23.05"; repo = "nixpkgs"; type =
"github"; }
is now instead:
nix-repl> :doc builtins.parseFlakeRef
Synopsis: builtins.parseFlakeRef flake-ref
Parse a flake reference, and return its exploded form.
For example:
| builtins.parseFlakeRef "github:NixOS/nixpkgs/23.05?dir=lib"
evaluates to:
| { dir = "lib"; owner = "NixOS"; ref = "23.05"; repo = "nixpkgs"; type = "github"; }
When querying all paths in a binary cache store, the path's representation
is `<hash>-x` (where `x` is the value of `MissingName`) because the .narinfo
filenames only contain the hash.
Before cc46ea1630 this worked correctly,
because the entire path info was read and the path from this
representation was printed, i.e. in the form `<hash>-<name>`. Since then
however, the direct result from `queryAllValidPaths()` was used as `path`.
Added a regression test to make sure the behavior remains correct.
This was part of approved PR #10021. Unfortunately that one is stalled
on a peculiar Linux test timeout, so trying to get bits of it merged
first to bisect failure.
Forcing a conditional include, vs making the headers content
conditional, I think is more maintainable.
It is also how the other platform-specific headers (like
`namespaces.hh`) have been adapted.
A possible use of them might have been to figure out the paths
(which can now be retrieved with maybePathsOut), but I have
not found evidence that it was used this way, and it would have
been broken, because non-CA outputs weren't recorded in the map.
It's a little weird we don't check the return status for these, but
changing that would introduce risk so I did not.
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
This introduces new utility functions to get elements from JSON — in an ergonomic way and with nice error messages if the expected type does not match.
Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>
* show Nix logo in the manual
the location of files is hard-coded by mdBook.
there is also seems to be no way to define custom templates, therefore
all styling has to be done in the CSS override.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This splits files and adds new identifiers in preperation for supporting
windows, but no Windows-specific code is actually added yet.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This patch makes `makeDecompressionSink` strip only a single layer
of compression specified via method. This fixes erroneous decompression
of doubly-compressed NARs fetched with curl.
This function is nice for more than `PosixSourceAccessor`. We can make a
few things simpler with it.
Note that the error logic slightly changes in some of the call sites, in
that we also count `ENOTDIR` and not just `ENOENT` as not having the
file, but that should be fine.
HintFmt(string) invokes the HintFmt("%s", literal) constructor,
which is not what we want here. Add a constructor with a proper name
and call that.
Next step: rename all the other ones to HintFmt::literal(string).
Fixes https://github.com/NixOS/nix/issues/10238
Thunks are now overwritten by a helper function
`Value::finishValue(newType, payload)` (where `payload` is the
original anonymous union inside `Value`). This helps to ensure we
never update a value elsewhere, since that would be incompatible with
parallel evaluation (i.e. after a value has transitioned from being a
thunk to being a non-thunk, it should be immutable).
There were two places where this happened: `Value::mkString()` and
`ExprAttrs::eval()`.
This PR also adds a bunch of accessor functions for value contents,
like `Value::integer()` to access the integer field in the union.
I realized it was checking NAR hashes before of added objects, which
makes little sense --- we don't really care about ancillary NAR hashes.
Now, the bottom `nix store add` tests compare the CA field with a git
hash to hashes calculated by Git. This matches top `nix hash path` ones
in using git as a source of truth.
Fixes an instance of
nix: src/libutil/util.cc:139: nix::Path nix::canonPath(PathView, bool): Assertion `path != ""' failed.
... which I've been getting in one of my shells for some reason.
I have yet to find out why TMPDIR was empty, but it's no reason for
Nix to break.
I was using by mistake the .#nix-clangStdenv shell to retrieve clangd.
This clangd is unusable with the project and constantly segfaults.
Let's explicitly state which shell the user should use in the docs.
I don't really understand the source of this segfault. I assume it's
related to a clang version incompatibility. (16.0.6 for
.#nix-clangStdenv 14.0.6 for .#native-clangStdenvPackages)
Fixes
terminate called after throwing an instance of 'boost::wrapexcept<boost::io::too_few_args>'
what(): boost::too_few_args: format-string referred to more arguments than were passed
Aborted (core dumped)
for type errors in AttrCursor.
- Align the “frequent” release cycle with the calendar
- The 6-month release cycle is hard to keep track of. A monthly
release will make it much easier to remember the release date.
- Officialise the support for a stable version maintained for as long as NixOS stable
- This is already the case in practice, it just happens that the
“stable” Nixpkgs version is whichever version was deemed
stable-enough at the time of the NixOS release.
Officialise that by cutting a new major release alongside each NixOS one.
Note that this breaks whatever semver compatibility Nix might pretend to
have, but I don't think it makes sense any way.
In a daemon-based Nix setup, some options cannot be overridden by a
client unless the client's user is considered trusted.
Currently, if an untrusted user tries to override one of those
options, we are silently ignoring it.
This can be pretty confusing in certain situations.
e.g. a user thinks he disabled the sandbox when in reality he did not.
We are now sending a warning message letting know the user some options
have been ignored.
Related to #1761.
This is a cherry-pick of 9e0f5f803f.
The above commit has been reverted by
a59e77d9e5 to prevent spamming warnings
with experimental features, but these are now totally ignored on the
daemon side, so there's no reason for the revert any more.
Previously, `state.mkList()` would set the type of the value to tList
and allocate the list vector, but it would not initialize the values
in the list. This has two problems:
* If an exception occurs, the list is left in an undefined state.
* More importantly, for multithreaded evaluation, if a value
transitions from thunk to non-thunk, it should be final (i.e. other
threads should be able to access the value safely).
To address this, there now is a `ListBuilder` class (analogous to
`BindingsBuilder`) to build the list vector prior to the call to
`Value::mkList()`. Typical usage:
auto list = state.buildList(size);
for (auto & v : list)
v = ... set value ...;
vRes.mkList(list);
* Add regression test
* Fix 'no repo' test so it doesn't succeed if the data is still in cache
* Use git_revparse_single inside git-utils instead of reimplementing the same logic.
Add `runHook preInstallCheck` to the overriden `installCheckPhase` used
for the non-build case.
In particular, this allow the fix from 2a34510776
to also apply there.
Previously, errors while printing values in `nix repl` would be printed
in `«error: ...»` brackets rather than displayed normally:
```
nix-repl> legacyPackages.aarch64-darwin.pythonPackages.APScheduler
«error: Package ‘python-2.7.18.7’ in /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/pkgs/development/interpreters/python/cpython/2.7/default.nix:335 is marked as insecure, refusing to evaluate.»
```
Now, errors will be displayed normally if they're emitted at the
top-level of an expression:
```
nix-repl> legacyPackages.aarch64-darwin.pythonPackages.APScheduler
error:
… in the condition of the assert statement
at /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/lib/customisation.nix:268:17:
267| in commonAttrs // {
268| drvPath = assert condition; drv.drvPath;
| ^
269| outPath = assert condition; drv.outPath;
… in the left operand of the OR (||) operator
at /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/pkgs/development/interpreters/python/passthrufun.nix:28:45:
27| if lib.isDerivation value then
28| lib.extendDerivation (valid value || throw "${name} should use `buildPythonPackage` or `toPythonModule` if it is to be part of the Python packages set.") {} value
| ^
29| else
(stack trace truncated; use '--show-trace' to show the full trace)
error: Package ‘python-2.7.18.7’ in /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/pkgs/development/interpreters/python/cpython/2.7/default.nix:335 is marked as insecure, refusing to evaluate.
```
Errors emitted in nested structures (like e.g. when printing `nixpkgs`)
will still be printed in brackets.
Strings are now printed directly when evaluated by `:print`, rather than
escaped. This makes it easier to debug multi-line strings or strings
containing quotes, like the results of `builtins.readFile`,
`lib.toShellArg`, and so on.
```
nix-repl> "cuppy\ndog\ncity"
"cuppy\ndog\ncity"
nix-repl> :p "cuppy\ndog\ncity"
cuppy
dog
city
```
Fixes this very long warning, which I'll only include the first line of:
/nix/store/8wrjhrycpshhc3b41xmjwvgqr2m3yajq-libcxx-16.0.6-dev/include/c++/v1/__memory/construct_at.h:66:5: warning: destructor called on non-final 'RegexMatcher' that has virtual functions but non-virtual destructor [-Wdelete-non-abstract-non-virtual-dtor]
__loc->~_Tp();
`nix eval` forces values and prints derivations as attribute sets, so
commands that print derivations (e.g. `nix eval nixpkgs#bash`) will
infinitely loop and segfault.
Printing derivations as `.drv` paths makes `nix eval` complete as
expected. Further work is needed, but this is better than a segfault.
`nix-env -qaP`'s output has changed a bit because of https://github.com/NixOS/nix/issues/10132.
Although that's a bit annoying, it isn't nearly as problematic as the
evaluation changes that this test is supposed to catch. So it's find to
just update the hash for the time being and fix the issue later
(properly fixing the issue will very likely change the hash any way).
Currently there isn't a convenient way to check for multiline output. In
addition, these outputs will easily change and having a diff between the
expected an the actual output upon failures is convenient.
This wasn't caught by CI because #10149 and #10152 pass
individually... It doesn't happen on lazy-trees either because we
never try to fetch relative path flakes (#10089).
we now keep not a table of all positions, but a table of all origins and
their sizes. position indices are now direct pointers into the virtual
concatenation of all parsed contents. this slightly reduces memory usage
and time spent in the parser, at the cost of not being able to report
positions if the total input size exceeds 4GiB. this limit is not unique
to nix though, rustc and clang also limit their input to 4GiB (although
at least clang refuses to process inputs that are larger, we will not).
this new 4GiB limit probably will not cause any problems for quite a
while, all of nixpkgs together is less than 100MiB in size and already
needs over 700MiB of memory and multiple seconds just to parse. 4GiB
worth of input will easily take multiple minutes and over 30GiB of
memory without even evaluating anything. if problems *do* arise we can
probably recover the old table-based system by adding some tracking to
Pos::Origin (or increasing the size of PosIdx outright), but for time
being this looks like more complexity than it's worth.
since we now need to read the entire input again to determine the
line/column of a position we'll make unsafeGetAttrPos slightly lazy:
mostly the set it returns is only used to determine the file of origin
of an attribute, not its exact location. the thunks do not add
measurable runtime overhead.
notably this change is necessary to allow changing the parser since
apparently nothing supports nix's very idiosyncratic line ending choice
of "anything goes", making it very hard to calculate line/column
positions in the parser (while byte offsets are very easy).
this needs a string comparison because there seems to be no other way to
get that information out of bison. usually the location info is going to
be correct (pointing at a bad token), but since EOF isn't a token as
such it'll be wrong in that this case.
this hasn't shown up much so far because a single line ending *is* a
token, so any file formatted in the usual manner (ie, ending in a line
ending) would have its EOF position reported correctly.
the parser treats a plain \r as a newline, error reports do not. this
can lead to interesting divergences if anything makes use of this
feature, with error reports pointing to wrong locations in the input (or
even outside the input altogether).
previously we reported the error at the beginning of the binding
block (for plain inherits) or the beginning of the attr list (for
inherit-from), effectively hiding where exactly the error happened.
this also carries over to runtime positions of attributes in sets as
reported by unsafeGetAttrPos. we're not worried about this changing
observable eval behavior because it *is* marked unsafe, and the new
behavior is much more useful.
we already normalize attr order to lexicographic, doing the same for
formals makes sense. doubly so because the order of formals would
otherwise depend on the context of the expression, which is not quite as
useful as one might expect.
the parser modifies its inputs, which means that sharing them between
the error context reporting system and the parser itself can confuse the
reporting system. usually this led to early truncation of error context
reports which, while not dangerous, can be quite confusing.
* Convert all InputScheme::fetch() methods to getAccessor().
* Add checkLocks() method for checking lock attributes.
* Rename fetch() to fetchToStore().
This is the case for e.g. dirty Git workdirs, where we would get
$ nix flake metadata
Resolved URL: git+file:///home/eelco/Dev/nix-master
Locked URL: git+file:///home/eelco/Dev/nix-master
The "lockedRef" field is a misnomer, since it can be unlocked
(e.g. for a dirty Git workdir). In that case, `nix profile upgrade`
needs to assume that the package can have changed, and perform an
upgrade.
When reviewing old PRs, I found that #9997 adds some code to ensure one
particular assert is always present. But, removing asserts isn't
something we do in our own release builds either in the flake here or in
nixpkgs, and is plainly a bad idea that increases support burden,
especially if other distros make bad choices of build flags in their Nix
packaging.
For context, the assert macro in the C standard is defined to do nothing
if NDEBUG is set.
There is no way in our build system to set -DNDEBUG without manually
adding it to CFLAGS, so this is simply a configuration we do not use.
Let's ban it at compile time.
I put this preprocessor directive in src/libutil.cc because it is not
obvious where else to put it, and it seems like the most logical file
since you are not getting a usable nix without it.
Directly fail if a flakeref points to something that isn't a directory
instead of falling back to the logic of trying to look up the hierarchy
to find a valid flake root.
Fix https://github.com/NixOS/nix/issues/9868
After https://github.com/NixOS/nix/pull/10071, the CI was trying to push
ghcr.io/nixos/nix:master for backwards-compatibility, but the image was
not tagged as such, causing the job to fail.
Fix this.
It is possible to exfiltrate a file descriptor out of the build sandbox
of FODs, and use it to modify the store path after it has been
registered.
To avoid that issue, don't register the output of the build, but a copy
of it (that will be free of any leaked file descriptor).
`NIX_HARDENING_ENABLE` causes `_FORTIFY_SOURCE` to be defined.
This isn't compatible with `-O0`, and the compiler will happily remind
us about it at every call, spamming the terminal with warnings and stack
traces.
We don't really care hardening in that case, so just disable it if we
pass `OPTIMIZE=0`.
Just `stdenv.isDarwin` isn't enough because it doesn't apply to the
build platform, which mean that cross packages building from darwin to
another platform will have `isDarwin` set to false.
Replace it by `stdenv.buildPlatform.isDarwin`.
Instead, serialize as NAR and send that over, then rehash sever side.
This is alorithmically simpler, but comes at the cost of a newer
parameter to `Store::addToStoreFromDump`.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
desugaring inherit-from to syntactic duplication of the source expr also
duplicates side effects of the source expr (such as trace calls) and
expensive computations (such as derivationStrict).
Flakes still reside in the Nix store (so there shouldn't be any change
in behaviour), but they are now accessed via the rootFS
accessor. Since rootFS implements access checks, we no longer have to
worry about flake.{nix,lock} or their parents being symlinks that
escape from the flake.
Extracted from the lazy-trees branch.
"hash type" -> "hash algorithm" in all comments, documentation, and
messages.
ht -> ha, [Hh]ashType -> [HhashAlgo] for all local variables and
function arguments. No API change is made.
Continuation of 5334c9c792 and 837b889c41.
After commit 91b6833686 (" Move tests to separate directories, and
document"), previously-built test executables are now tracked by Git,
which is annoying for developers.
This patch add .gitignore rules to ignore the obsolete test directories
to solve such problem and enhance developer experience.
The sandbox rule `(allow network* (local ip))` doesn't do what it
implies. Adding this rule permits all network traffic. We should be
matching on (remote ip "localhost:*")` instead.
This seems to have found one actual bug in fs-sink.cc: the symlink case
was falling into the regular file case, which can't possibly be
intentional, right?
Docker uses "latest" as the default label instead of "master".
This change will allow to docker run ghcr.io/nixos/nix without having to
specify the label.
It keeps the :master label on docker hub for back-compat.
When a file conflict arises during a package install a suggestion is
made to remove the old entry. This was previously done using the
installable URLs of the old entry. These URLs are quite verbose and
often do not equal the URL of the existing entry.
This change uses the recently introduced profile entry name for the
suggestion, resulting in a simpler output.
The improvement is easily seen in the change to the functional test.
- `nix store add` supports text hashing
With functional test ensuring it matches `builtins.toFile`.
- Factored-out flags for both commands
- Move all common reusable flags to `libcmd`
- They are not part of the *definition* of the CLI infra, just a usag
of it.
- The `libstore` flag couldn't go in `args.hh` in libutil anyways,
would be awkward for it to live alone
- Shuffle around `Cmd*` hierarchy so flags for deprecated commands don't
end up on the new ones
This PR reduces the creation of short-lived basic_json objects while
parsing flake.lock files. For large flake.lock files (~1.5MB) I was
observing ~60s being spent for trivial nix build operations while
after this change it is now taking ~1.6s.
It's better to just check whether the input has all the attributes
needed to consider itself locked (e.g. whether a Git input has an
'rev' attribute).
Also, the 'locked' field was actually incorrect for Git inputs: it
would be set to true even for dirty worktrees. As a result, we got
away with using fetchTree() internally even though fetchTree()
requires a locked input in pure mode. In particular, this allowed
'--override-input' to work by accident.
The fix is to pass a set of "overrides" to call-flake.nix for all the
unlocked inputs (i.e. the top-level flake and any --override-inputs).
This fixes warnings like
warning: Ignoring setting 'auto-allocate-uids' because experimental feature 'auto-allocate-uids' is not enabled
warning: Ignoring setting 'impure-env' because experimental feature 'configurable-impure-env' is not enabled
when using the daemon and the user didn't actually set those settings.
Note: this also hides those settings from `nix config show`, but that
seems a good thing.
`canonPath` and `absPath` work on native paths, and so should switch
between supporting Unix paths and Windows paths accordingly.
The templating is because `CanonPath`, which shares the implementation,
should always be Unix style. It is the pure "nix-native" path type for
virtual file operations --- it is part of Nix's "business logic", and
should not vary with the host OS accordingly.
The core `CanonPath` constructors were using `absPath`, but `absPath` in
some situations does IO which is not appropriate. It turns out that
these constructors avoided those situations, and thus were pure, but it
was far from obvious this was the case.
To remedy the situation, abstract the core algorithm from `canonPath` to
use separately in `CanonPath` without any IO. No we know by-construction
that those constructors are pure.
That leaves `CanonPath::fromCWD` as the only operation which uses IO /
is impure. Add docs on it, and `CanonPath` as a whole, explaining the
situation.
This is also necessary to support Windows paths on windows without
messing up `CanonPath`. But, I think it is good even without that.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
There is no longer an `importTarball` method. Instead, there is a
`unpackTarfileToSink` function (back in libutil). The caller can use
thisw with the `getParseSink` method we added in the last commit easily
enough.
In addition, tarball cache functionality is separated from `git-utils`
and moved into `tarball-cache`. This ensures we are separating mechanism
and policy.
There is now a separation of:
1. A `FileSystemObjectSink` for writing to git repos
2. Adapting libarchive to use that parse sink.
The prepares a proper separation of concerns.
A command like
rm -rf ~/.cache/nix/tarball-cache/ ~/.cache/nix/fetcher-cache-v1.sqlite*; nix flake metadata 'git+file:///home/eelco/Dev/nixpkgs?rev=9463103069725474698139ab10f17a9d125da859'
was spending about 84% of its runtime in lookup(), specifically in
git_tree_entry_bypath(). (The reading of blobs is less than 3%.)
It appears libgit2 doesn't do a lot of caching of trees, so we now
make sure that when we look up a path, we add all its parents, and all
the immediate children of the parents (since we have them in memory
anyway), to our own cache.
This speed up the command above from 17.2s to 7.8s on my machine.
Fixes (or at least should improve a lot) #9684.
Commit 83c067c0fa changed `builtins.pathExists`
to resolve symlinks before checking for existence. Consequently, if the path
refers to a symlink itself, existence of the target of the symlink (instead of
the symlink itself) was checked. Restore the previous behavior by skipping
symlink resolution in the last component.
No outward facing behavior is changed.
Older methods with same names that operate on on method + algo pair (for
old-style `<method>:algo`) are renamed to `*WithAlgo`.)
The functions are unit-tested in the same way the names for the hash
algorithms are tested.
* reword description of the `cores` setting
- be precise about the `builder` executable
- clearly distinguish between `builder` and job parallelism
- clarify the role of `mkDerivation` in the example
- remove prose for the default, it's shown programmatically
- mention relation to `max-jobs`
- move all reference documentation to the `builders` configuration setting
- reword documentation on machine specification, add examples
- disable showing the default value, as it rendered as `@/dummy/machines`, which is wrong
- highlight the examples
- link to the configuration docs for distributed builds
- builder -> build machine
Co-authored-by: Janik H <janik@aq0.de>
the interesting information is on the proper pages, and is now presented
a bit more prominently.
the paragraph was a bit confusing to read, also because an anchor link
to an inline definition was in the middle of the sentence. "local store"
now has its own glossary entry.
The symbolic form in use here doesn't seem to have an effect
in either the BSD or coreutils install commands, leaving the
daemon plist with empty permissions. This seems to cause its
own problems.
I think I've got the right symbolic syntax now :)
for plain inherits this is really just a stylistic choice, but for
inherit-from it actually fixes an exponential size increase problem
during expr printing (as may happen during assertion failure reporting,
on during duplicate attr detection in the parser)
this also has the effect of sorting let bindings lexicographically
rather than by symbol creation order as was previously done, giving a
better canonicalization in the process.
There's probably more that can be said, but I thought it might be helpful to put something here about how to access elements of a list for folks coming from more or less any other programming language. If this is rarely used, it might be nice to add to the documentation something about why it's rarely used.
Commit d536c57e87 inadvertedly broke build and
installation of all non-autogenerated manual pages (in particular, all the ones
documenting the stable CLI), by moving the definition of the man-pages variable
in doc/manual/local.mk after its usage in mk/lib.mk. Move including the former
earlier so that the correct order is restored.
how the different invocations relate to each other seems be
confusing, which is relatable because one has to wire it up in your head
while reading. an explicit reference should make it unambiguous and
easier to notice due to links being highlighted.
autoconf authors apparently decided that setting `-O2` by default was a good idea. I disagree, and Nix has its own way of deciding that (with `OPTIMIZE={0,1}`). Explicitly set `CFLAGS` and `CXXFLAGS` in the configure script to disable that behaviour.
Fix#9965
When I started contributing to Nix, I found the mix of definitions and
names in `fmt.hh` to be rather confusing, especially the small
difference between `hintfmt` and `hintformat`. I've renamed many classes
and added documentation to most definitions.
- `formatHelper` is no longer exported.
- `fmt`'s documentation is now with `fmt` rather than (misleadingly)
above `formatHelper`.
- `yellowtxt` is renamed to `Magenta`.
`yellowtxt` wraps its value with `ANSI_WARNING`, but `ANSI_WARNING`
has been equal to `ANSI_MAGENTA` for a long time. Now the name is
updated.
- `normaltxt` is renamed to `Uncolored`.
- `hintfmt` has been merged into `hintformat` as extra constructor
functions.
- `hintformat` has been renamed to `hintfmt`.
- The single-argument `hintformat(std::string)` constructor has been
renamed to a static member `hintformat::interpolate` to avoid pitfalls
with using user-generated strings as format strings.
As discussed in the last Nix team meeting (2024-02-95), this method
doesn't belong because `CanonPath` is a virtual/ideal absolute path
format, not used in file systems beyond the native OS format for which a
"current working directory" is defined.
Progress towards #9205
Pretty-print values in the REPL by printing each item in a list or
attrset on a separate line. When possible, single-item lists and
attrsets are printed on one line, as long as they don't contain a nested
list, attrset, or thunk.
Before:
```
{ attrs = { a = { b = { c = { }; }; }; }; list = [ 1 ]; list' = [ 1 2 3 ]; }
```
After:
```
{
attrs = {
a = {
b = {
c = { };
};
};
};
list = [ 1 ];
list' = [
1
2
3
];
}
```
Some tools which consume the "nix print-dev-env" rc script (such as
"nix-direnv") are sensitive to the use of unbound variables. They use
"set -u".
The "nix print-dev-env" rc script initially unsets "shellHook", then
loads variables from the derivation, and then evaluates "shellHook".
However, most derivations don't have a "shellHook" attribute.
So users get the error "shellHook: unbound variable". This can be
demonstrated with the command:
nix print-dev-env nixpkgs#hello | bash -u
This commit changes the rc script to provide an empty fallback value
for the "shellHook" variable.
Closes: #7951#8253
It is entirely possible for the path to be an empty string and many
unit tests actually pass it as an empty string (e.g. both_roundrip or
turnsEmptyPathIntoCWD). In this case, without this patch, absPath will
perform a one-byte out-of-bounds access.
This was discovered while enabling the nix test suite on Alpine where
we compile all software with `-D_GLIBCXX_ASSERTIONS=1`, thus resulting
in a test failure on Alpine.
While preparing PRs like #9753, I've had to change error messages in
dozens of code paths. It would be nice if instead of
EvalError("expected 'boolean' but found '%1%'", showType(v))
we could write
TypeError(v, "boolean")
or similar. Then, changing the error message could be a mechanical
refactor with the compiler pointing out places the constructor needs to
be changed, rather than the error-prone process of grepping through the
codebase. Structured errors would also help prevent the "same" error
from having multiple slightly different messages, and could be a first
step towards error codes / an error index.
This PR reworks the exception infrastructure in `libexpr` to
support exception types with different constructor signatures than
`BaseError`. Actually refactoring the exceptions to use structured data
will come in a future PR (this one is big enough already, as it has to
touch every exception in `libexpr`).
The core design is in `eval-error.hh`. Generally, errors like this:
state.error("'%s' is not a string", getAttrPathStr())
.debugThrow<TypeError>()
are transformed like this:
state.error<TypeError>("'%s' is not a string", getAttrPathStr())
.debugThrow()
The type annotation has moved from `ErrorBuilder::debugThrow` to
`EvalState::error`.
Previously, the "file:./" prefix was not correctly recognized in
fixGitURL; instead, it was mistaken as a file path, which resulted in a
parsed url of the form "file://file:./".
This commit fixes the issue by properly detecting the "file:" prefix.
Note, however, that unlike "file://", the "file:./" URI is _not_
standardized, but has been widely used to referred to relative file
paths. In particular, the "git+file:./" did work for nix<=2.18, and was
broken since nix 2.19.0.
Finally, this commit fixes the issue completely for the 2.19 series, but
is still inadequate for the 2.20 series due to new behaviors from the
switch to libgit2. However, it does improve the correctness of parsing
even though it is not yet a complete solution.
As discussed in the maintainer meeting on 2024-01-29.
Mainly this is to avoid a situation where the name is parsed and
treated as a file name, mostly to protect users.
.-* and ..-* are also considered invalid because they might strip
on that separator to remove versions. Doesn't really work, but that's
what we decided, and I won't argue with it, because .-* probably
doesn't seem to have a real world application anyway.
We do still permit a 1-character name that's just "-", which still
poses a similar risk in such a situation. We can't start disallowing
trailing -, because a non-zero number of users will need it and we've
seen how annoying and painful such a change is.
What matters most is preventing a situation where . or .. can be
injected, and to just get this done.
GitArchiveInputScheme now streams tarballs into a Git repository. This
deduplicates data a lot, e.g. when you're fetching different revisions
of the Nixpkgs repo. It also warns if the tree hash returned by GitHub
doesn't match the tree hash of the imported tarball.
When writing a shebang script, you expect your path to be relative to
the script, not the cwd. We previously handled this correctly for
relative file paths, but not for expressions.
This handles both -p & -E args. My understanding is this should be
what we want in any cases I can think of - people run scripts from
many different working directories. @edolstra is there any reason to
handle -p args differently in this case?
Fixes#4232
These docs explain the implementation relative to the local store
originals. The original declaration of virtual methods can still be
consulted for proper interface-level documentation.
As an optimisation for LocalStore, we read all the store directory entries into
a set. Checking for membership of this set is much faster than a stat syscall.
However for LocalOverlayStore, the lower store directory is expected to contain
a vast number of entries and reading them all can take a very long time.
So instead of enumerating them all upfront, we call pathExists as needed. This
means making stat syscalls for each store path, but the upper layer is expected
to be relatively small compared to the lower store so that should be okay.
Grouping our tests should make it easier to understand the intent than
one long poorly-arranged list. It also is convenient for running just
the tests for a specific component when working on that component.
We need at least one test group so this isn't dead code; I decided to
collect the tests for the `ca-derivations` and `dynamic-derivations`
experimental features in groups. Do
```bash
make ca.test-group -jN
```
and
```bash
make dyn-drv.test-group -jN
```
to try running just them.
I originally did this as part of #8397 for being able to just the local
overlay store alone. I am PRing it separately now so we can separate
general infra from new features.
This requires switching on SQLITE_OPEN_URI because there is no open flag to
make the database immutable. Without immutable, sqlite will still attempt to
create journal and wal files, even when the database is opened read-only.
https://www.sqlite.org/c3ref/open.html
The immutable parameter is a boolean query parameter that indicates that the
database file is stored on read-only media. When immutable is set, SQLite
assumes that the database file cannot be changed, even by a process with higher
privilege, and so the database is opened read-only and all locking and change
detection is disabled.
Nix does not manage the overlayfs mount point itself, but the correct
functioning of the overlay store does depend on this mount point being set up
correctly. Rather than just assume this is the case, check that the lowerdir
and upperdir options are what we expect them to be. This check is on by
default, but can be disabled if needed.
# 2. Create a cache for $githubuser-nix-install-tests
# 3. Create a cachix auth token and save it in https://github.com/$githubuser/nix/settings/secrets/actions in "Repository secrets" as CACHIX_AUTH_TOKEN
# Dockerhub:
# 1. Sign-up for https://hub.docker.com/
# 2. Store your dockerhub username as DOCKERHUB_USERNAME in "Repository secrets" of your fork repository settings (https://github.com/$githubuser/nix/settings/secrets/actions)
# 3. Create an access token in https://hub.docker.com/settings/security and store it as DOCKERHUB_TOKEN in "Repository secrets" of your fork
@@ -27,6 +27,8 @@ Check out the [security policy](https://github.com/NixOS/nix/security/policy).
1. Search for related issues that cover what you're going to work on.
It could help to mention there that you will work on the issue.
We strongly recommend first-time contributors not to propose new features but rather fix tightly-scoped problems in order to build trust and a working relationship with maintainers.
Issues labeled [good first issue](https://github.com/NixOS/nix/labels/good%20first%20issue) should be relatively easy to fix and are likely to get merged quickly.
Pull requests addressing issues labeled [idea approved](https://github.com/NixOS/nix/labels/idea%20approved) or [RFC](https://github.com/NixOS/nix/labels/RFC) are especially welcomed by maintainers and will receive prioritised review.
@@ -39,9 +41,9 @@ Check out the [security policy](https://github.com/NixOS/nix/security/policy).
There are many open pull requests that might already do what you intend to work on.
You can use [labels](https://github.com/NixOS/nix/labels) to filter for relevant topics.
3. Check the [Nix reference manual](https://nixos.org/manual/nix/unstable/contributing/hacking.html) for information on building Nix and running its tests.
3. Check the [Nix reference manual](https://nix.dev/manual/nix/development/development/building.html) for information on building Nix and running its tests.
For contributions to the command line interface, please check the [CLI guidelines](https://nixos.org/manual/nix/unstable/contributing/cli-guideline.html).
For contributions to the command line interface, please check the [CLI guidelines](https://nix.dev/manual/nix/development/development/cli-guideline.html).
4. Make your change!
@@ -63,11 +65,11 @@ Check out the [security policy](https://github.com/NixOS/nix/security/policy).
- [ ] User documentation in the [manual](..doc/manual/src)
- [ ] User documentation in the [manual](./doc/manual/src)
- [ ] API documentation in header files
- [ ] Code and comments are self-explanatory
- [ ] Commit message explains **why** the change was made
- [ ] New feature or incompatible change: updated [release notes](./doc/manual/src/release-notes/rl-next.md)
- [ ] New feature or incompatible change: [add a release note](https://nix.dev/manual/nix/development/development/contributing.html#add-a-release-note)
7. If you need additional feedback or help to getting pull request into shape, ask other contributors using [@mentions](https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax#mentioning-people-and-teams).
@@ -76,7 +78,7 @@ Check out the [security policy](https://github.com/NixOS/nix/security/policy).
The Nix reference manual is hosted on https://nixos.org/manual/nix.
The underlying source files are located in [`doc/manual/src`](./doc/manual/src).
For small changes you can [use GitHub to edit these files](https://docs.github.com/en/repositories/working-with-files/managing-files/editing-files)
For larger changes see the [Nix reference manual](https://nixos.org/manual/nix/unstable/contributing/hacking.html).
For larger changes see the [Nix reference manual](https://nix.dev/manual/nix/development/development/contributing.html).
Nix is a powerful package manager for Linux and other Unix systems that makes package
management reliable and reproducible. Please refer to the [Nix manual](https://nixos.org/nix/manual)
management reliable and reproducible. Please refer to the [Nix manual](https://nix.dev/reference/nix-manual)
for more details.
## Installation and first steps
Visit [nix.dev](https://nix.dev) for [installation instructions](https://nix.dev/tutorials/install-nix) and [beginner tutorials](https://nix.dev/tutorials/first-steps).
Full reference documentation can be found in the [Nix manual](https://nixos.org/nix/manual).
Full reference documentation can be found in the [Nix manual](https://nix.dev/reference/nix-manual).
## Building And Developing
## Building and developing
See our [Hacking guide](https://nixos.org/manual/nix/unstable/contributing/hacking.html) in our manual for instruction on how to
set up a development environment and build Nix from source.
Follow instructions in the Nix reference manual to [set up a development environment and build Nix from source](https://nix.dev/manual/nix/development/building.html).
## Contributing
Check the [contributing guide](./CONTRIBUTING.md) if you want to get involved with developing Nix.
## Additional Resources
## Additional resources
- [Nix manual](https://nixos.org/nix/manual)
- [Nix jobsets on hydra.nixos.org](https://hydra.nixos.org/project/nix)
Nix was created by Eelco Dolstra and developed as the subject of his PhD thesis [The Purely Functional Software Deployment Model](https://edolstra.github.io/pubs/phd-thesis.pdf), published 2006.
Today, a world-wide developer community contributes to Nix and the ecosystem that has grown around it.
- [The Nix, Nixpkgs, NixOS Community on nixos.org](https://nixos.org/)
- [Official documentation on nix.dev](https://nix.dev)
- [Nixpkgs](https://github.com/NixOS/nixpkgs) is [the largest, most up-to-date free software repository in the world](https://repology.org/repositories/graphs)
- [NixOS](https://github.com/NixOS/nixpkgs/tree/master/nixos) is a Linux distribution that can be configured fully declaratively
# State should be stored in /nix/var, unless the user overrides it explicitly.
test "$localstatedir" = '${prefix}/var' && localstatedir=/nix/var
# Assign a default value to C{,XX}FLAGS as the default configure script sets them
# to -O2 otherwise, which we don't want to have hardcoded
CFLAGS=${CFLAGS-""}
CXXFLAGS=${CXXFLAGS-""}
AC_PROG_CC
AC_PROG_CXX
@@ -59,7 +63,6 @@ AC_SYS_LARGEFILE
# Solaris-specific stuff.
AC_STRUCT_DIRENT_D_TYPE
case "$host_os" in
solaris*)
# Solaris requires -lsocket -lnsl for network functions
@@ -163,11 +166,6 @@ AS_IF(
[test "$ENABLE_BUILD" == "no" && test "$ENABLE_DOC_GEN" == "yes"],
[AC_MSG_ERROR([Cannot enable generated docs when building overall is disabled. Please do not pass '--enable-doc-gen' or do not pass '--disable-build'.])])
# Building without API docs is the default as Nix' C++ interfaces are internal and unstable.
AC_ARG_ENABLE(internal-api-docs, AS_HELP_STRING([--enable-internal-api-docs],[Build API docs for Nix's internal unstable C++ interfaces]),
@@ -12,14 +12,14 @@ machine is accessible via SSH and that it has Nix installed. You can
test whether connecting to the remote Nix instance works, e.g.
```console
$ nix store info --store ssh://mac
$ nix store ping --store ssh://mac
```
will try to connect to the machine named `mac`. It is possible to
specify an SSH identity file as part of the remote store URI, e.g.
```console
$ nix store info --store ssh://mac?ssh-key=/home/alice/my-key
$ nix store ping --store ssh://mac?ssh-key=/home/alice/my-key
```
Since builds should be non-interactive, the key should not have a
@@ -36,16 +36,8 @@ error: cannot connect to 'mac'
then you need to ensure that the `PATH` of non-interactive login shells
contains Nix.
> **Warning**
>
> If you are building via the Nix daemon, it is the Nix daemon user account (that is, `root`) that should have SSH access to a user (not necessarily `root`) on the remote machine.
>
> If you can’t or don’t want to configure `root` to be able to access the remote machine, you can use a private Nix store instead by passing e.g. `--store ~/my-nix` when running a Nix command from the local machine.
The list of remote machines can be specified on the command line or in
the Nix configuration file. The former is convenient for testing. For
example, the following command allows you to build a derivation for
`x86_64-darwin` on a Linux machine:
The [list of remote build machines](@docroot@/command-ref/conf-file.md#conf-builders) can be specified on the command line or in the Nix configuration file.
For example, the following command allows you to build a derivation for `x86_64-darwin` on a Linux machine:
```console
$ uname
@@ -60,97 +52,20 @@ $ cat ./result
Darwin
```
It is possible to specify multiple builders separated by a semicolon or
a newline, e.g.
It is possible to specify multiple build machines separated by a semicolon or a newline, e.g.
A colon-separated list of search path entries used to resolve [lookup paths](@docroot@/language/constructs/lookup-path.md).
If `NIX_PATH` is not set at all, Nix will fall back to the following list in [impure](@docroot@/command-ref/conf-file.md#conf-pure-eval) and [unrestricted](@docroot@/command-ref/conf-file.md#conf-restrict-eval) evaluation mode:
This environment variable overrides the value of the [`nix-path` configuration setting](@docroot@/command-ref/conf-file.md#conf-nix-path).
This is the equivalent of invoking `nix-env --delete-generations old` on each found profile.
This is the equivalent of invoking [`nix-env --delete-generations old`](@docroot@/command-ref/nix-env/delete-generations.md#generations-old) on each found profile.
`nix-copy-closure` - copy a closure to or from a remote machine via SSH
`nix-copy-closure` - copy store objects to or from a remote machine via SSH
# Synopsis
`nix-copy-closure`
[`--to` | `--from`]
[`--to` | `--from`]
[`--gzip`]
[`--include-outputs`]
[`--use-substitutes` | `-s`]
[`-v`]
_user@machine__paths_
[_user_@]_machine_[:_port_]_paths_
# Description
`nix-copy-closure` gives you an easy and efficient way to exchange
software between machines. Given one or more Nix store _paths_ on the
local machine, `nix-copy-closure` computes the closure of those paths
(i.e. all their dependencies in the Nix store), and copies all paths
in the closure to the remote machine via the `ssh` (Secure Shell)
command. With the `--from` option, the direction is reversed: the
closure of _paths_ on a remote machine is copied to the Nix store on
the local machine.
Given _paths_ from one machine, `nix-copy-closure` computes the [closure](@docroot@/glossary.md#gloss-closure) of those paths (i.e. all their dependencies in the Nix store), and copies [store objects](@docroot@/glossary.md#gloss-store-object) in that closure to another machine via SSH.
It doesn’t copy store objects that are already present on the other machine.
This command is efficient because it only sends the store paths
that are missing on the target machine.
> **Note**
>
> While the Nix store to use on the local machine can be specified on the command line with the [`--store`](@docroot@/command-ref/conf-file.md#conf-store) option, the Nix store to be accessed on the remote machine can only be [configured statically](@docroot@/command-ref/conf-file.md#configuration-file) on that remote machine.
Since `nix-copy-closure` calls `ssh`, you may be asked to type in the
appropriate password or passphrase. In fact, you may be asked _twice_
because `nix-copy-closure` currently connects twice to the remote
machine, first to get the set of paths missing on the target machine,
and second to send the dump of those paths. When using public key
authentication, you can avoid typing the passphrase with `ssh-agent`.
Since `nix-copy-closure` calls `ssh`, you may need to authenticate with the remote machine.
In fact, you may be asked for authentication _twice_ because `nix-copy-closure` currently connects twice to the remote machine: first to get the set of paths missing on the target machine, and second to send the dump of those paths.
When using public key authentication, you can avoid typing the passphrase with `ssh-agent`.
# Options
-`--to`\
Copy the closure of _paths_ from the local Nix store to the Nix
store on _machine_. This is the default.
-`--to`
-`--from`\
Copy the closure of _paths_ from the Nix store on _machine_ to the
local Nix store.
Copy the closure of _paths_ from a Nix store accessible from the local machine to the Nix store on the remote _machine_.
This is the default behavior.
-`--gzip`\
Enable compression of the SSH connection.
-`--from`
-`--include-outputs`\
Also copy the outputs of [store derivation]s included in the closure.
Copy the closure of _paths_ from the Nix store on the remote _machine_ to the local machine's specified Nix store.
Attempt to download missing store objects on the target from [substituters](@docroot@/command-ref/conf-file.md#conf-substituters).
Any store objects that cannot be substituted on the target are still copied normally from the source.
This is useful, for instance, if the connection between the source and target machine is slow, but the connection between the target machine and `cache.nixos.org` (the default binary cache server) is fast.
{{#include ./opt-common.md}}
# Environment variables
-`NIX_SSHOPTS`\
Additional options to be passed to `ssh` on the command
line.
-`NIX_SSHOPTS`
Additional options to be passed to `ssh` on the command line.
{{#include ./env-common.md}}
# Examples
Copy Firefox with all its dependencies to a remote machine:
> **Example**
>
> Copy GNU Hello with all its dependencies to a remote machine:
>
> ```shell-session
> $ storePath="$(nix-build '<nixpkgs>' -I nixpkgs=channel:nixpkgs-unstable -A hello --no-out-link)"
@@ -47,39 +47,83 @@ These pages can be viewed offline:
Example: `nix-env --help --install`
# Package sources
`nix-env` can obtain packages from multiple sources:
- An attribute set of derivations from:
- The [default Nix expression](@docroot@/command-ref/files/default-nix-expression.md) (by default)
- A Nix file, specified via `--file`
- A [profile](@docroot@/command-ref/files/profiles.md), specified via `--from-profile`
- A Nix expression that is a function which takes default expression as argument, specified via `--from-expression`
- A [store path](@docroot@/store/store-path.md)
# Selectors
Several commands, such as `nix-env --query` and `nix-env --install`, take a list of
arguments that specify the packages on which to operate. These are
extended regular expressions that must match the entire name of the
package. (For details on regular expressions, see **regex**(7).) The match is
case-sensitive. The regular expression can optionally be followed by a
dash and a version number; if omitted, any version of the package will
match. Here are some examples:
Several operations, such as [`nix-env --query`](./nix-env/query.md) and [`nix-env --install`](./nix-env/install.md), take a list of *arguments* that specify the packages on which to operate.
-`firefox`\
Matches the package name `firefox` and any version.
Packages are identified based on a `name` part and a `version` part of a [symbolic derivation name](@docroot@/language/derivations.md#attr-names):
-`firefox-32.0`\
Matches the package name `firefox` and version `32.0`.
-`name`: Everything up to but not including the first dash (`-`) that is *not* followed by a letter.
-`version`: The rest, excluding the separating dash.
-`gtk\\+`\
Matches the package name `gtk+`. The `+` character must be escaped
using a backslash to prevent it from being interpreted as a
quantifier, and the backslash must be escaped in turn with another
backslash to ensure that the shell passes it on.
> **Example**
>
> `nix-env` parses the symbolic derivation name `apache-httpd-2.0.48` as:
>
> ```json
> {
> "name": "apache-httpd",
> "version": "2.0.48"
> }
> ```
-`.\*`\
Matches any package name. This is the default for most commands.
> **Example**
>
> `nix-env` parses the symbolic derivation name `firefox.*` as:
>
> ```json
> {
> "name": "firefox.*",
> "version": ""
> }
> ```
-`'.*zip.*'`\
Matches any package name containing the string `zip`. Note the dots:
`'*zip*'` does not work, because in a regular expression, the
character `*` is interpreted as a quantifier.
The `name` parts of the *arguments* to `nix-env` are treated as extended regular expressions and matched against the `name` parts of derivation names in the package source.
The match is case-sensitive.
The regular expression can optionally be followed by a dash (`-`) and a version number; if omitted, any version of the package will match.
For details on regular expressions, see [**regex**(7)](https://linux.die.net/man/7/regex).
-`'.*(firefox|chromium).*'`\
Matches any package name containing the strings `firefox` or
`chromium`.
> **Example**
>
> Common patterns for finding package names with `nix-env`:
>
> - `firefox`
>
> Matches the package name `firefox` and any version.
>
> - `firefox-32.0`
>
> Matches the package name `firefox` and version `32.0`.
>
> - `gtk\\+`
>
> Matches the package name `gtk+`.
> The `+` character must be escaped using a backslash (`\`) to prevent it from being interpreted as a quantifier, and the backslash must be escaped in turn with another backslash to ensure that the shell passes it on.
>
> - `.\*`
>
> Matches any package name.
> This is the default for most commands.
>
> - `'.*zip.*'`
>
> Matches any package name containing the string `zip`.
> Note the dots: `'*zip*'` does not work, because in a regular expression, the character `*` is interpreted as a quantifier.
>
> - `'.*(firefox|chromium).*'`
>
> Matches any package name containing the strings `firefox` or `chromium`.
The install operation creates a new user environment.
The `--install` operation creates a new user environment.
It is based on the current generation of the active [profile](@docroot@/command-ref/files/profiles.md), to which a set of [store paths] described by *args* is added.
The arguments *args* map to store paths in a number of possible ways:
- By default, *args* is a set of [derivation] names denoting derivations in the [default Nix expression].
These are [realised], and the resulting output paths are installed.
Currently installed derivations with a name equal to the name of a derivation being added are removed unless the option `--preserve-installed` is specified.
- By default, *args* is a set of [derivation] names denoting derivations in the [default Nix expression].
These are [realised], and the resulting output paths are installed.
Currently installed derivations with a name equal to the name of a derivation being added are removed unless the option `--preserve-installed` is specified.
If there are multiple derivations matching a name in *args* that
have the same name (e.g., `gcc-3.3.6` and `gcc-4.1.1`), then the
derivation with the highest *priority* is used. A derivation can
define a priority by declaring the `meta.priority` attribute. This
attribute should be a number, with a higher value denoting a lower
priority. The default priority is `5`.
If there are multiple derivations matching a name in *args* that
have the same name (e.g., `gcc-3.3.6` and `gcc-4.1.1`), then the
derivation with the highest *priority* is used. A derivation can
define a priority by declaring the `meta.priority` attribute. This
attribute should be a number, with a higher value denoting a lower
priority. The default priority is `5`.
If there are multiple matching derivations with the same priority,
then the derivation with the highest version will be installed.
If there are multiple matching derivations with the same priority,
then the derivation with 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, `nix-env --install
gcc-3.3.6 gcc-4.1.1` will install both version of GCC (and will
probably cause a user environment conflict\!).
You can force the installation of multiple derivations with the same
name by being specific about the versions. For instance, `nix-env --install
gcc-3.3.6 gcc-4.1.1` will install both version of GCC (and will
probably cause a user environment conflict\!).
- If [`--attr`](#opt-attr) / `-A` is specified, the arguments are *attribute paths* that select attributes from the [default Nix expression].
This is faster than using derivation names and unambiguous.
Show the attribute paths of available packages with [`nix-env --query`](./query.md):
- If [`--attr`](#opt-attr) / `-A` is specified, the arguments are *attribute paths* that select attributes from the [default Nix expression].
This is faster than using derivation names and unambiguous.
Show the attribute paths of available packages with [`nix-env --query`](./query.md):
```console
nix-env --query --available --attr-path
```
```console
nix-env --query --available --attr-path`
```
- If `--from-profile` *path* is given, *args* is a set of names
denoting installed [store paths] in the profile *path*. This is an
easy way to copy user environment elements from one profile to
another.
- If `--from-profile` *path* is given, *args* is a set of names
denoting installed [store paths] in the profile *path*. This is an
easy way to copy user environment elements from one profile to
another.
- If `--from-expression` is given, *args* are [Nix language functions](@docroot@/language/syntax.md#functions) that are called with the [default Nix expression] as their single argument.
The derivations returned by those function calls are installed.
This allows derivations to be specified in an unambiguous way, which is necessary if there are multiple derivations with the same name.
- If `--from-expression` is given, *args* are [Nix language functions](@docroot@/language/constructs.md#functions) that are called with the [default Nix expression] as their single argument.
The derivations returned by those function calls are installed.
This allows derivations to be specified in an unambiguous way, which is necessary if there are multiple derivations with the same name.
- If *args* are [store derivations](@docroot@/glossary.md#gloss-store-derivation), then these are [realised], and the resulting output paths are installed.
- If *args* are [store derivations](@docroot@/glossary.md#gloss-store-derivation), then these are [realised], and the resulting output paths are installed.
- If *args* are [store paths] that are not storederivations, then these are [realised] and installed.
- If *args* are [store paths] that are not store derivations, then these are [realised] and installed.
- By default all [outputs](@docroot@/language/derivations.md#attr-outputs) are installed for each [derivation].
This can be overridden by adding a `meta.outputsToInstall` attribute on the derivation listing a subset of the output names.
- By default all [outputs](@docroot@/language/derivations.md#attr-outputs) are installed for each [derivation].
This can be overridden by adding a `meta.outputsToInstall` attribute on the derivation listing a subset of the output names.
Example:
Example:
The file `example.nix` defines a derivation with two outputs `foo` and `bar`, each containing a file.
The file `example.nix` defines a derivation with two outputs `foo` and `bar`, each containing a file.
```nix
# example.nix
let
pkgs = import <nixpkgs> {};
command = ''
${pkgs.coreutils}/bin/mkdir -p $foo $bar
echo foo > $foo/foo-file
echo bar > $bar/bar-file
'';
in
derivation {
name = "example";
builder = "${pkgs.bash}/bin/bash";
args = [ "-c" command ];
outputs = [ "foo" "bar" ];
system = builtins.currentSystem;
}
```
```nix
# example.nix
let
pkgs = import <nixpkgs> {};
command = ''
${pkgs.coreutils}/bin/mkdir -p $foo $bar
echo foo > $foo/foo-file
echo bar > $bar/bar-file
'';
in
derivation {
name = "example";
builder = "${pkgs.bash}/bin/bash";
args = [ "-c" command ];
outputs = [ "foo" "bar" ];
system = builtins.currentSystem;
}
```
Installing from this Nix expression will make files from both outputs appear in the current profile.
Installing from this Nix expression will make files from both outputs appear in the current profile.
```console
$ nix-env --install --file example.nix
installing 'example'
$ ls ~/.nix-profile
foo-file
bar-file
manifest.nix
```
```console
$ nix-env --install --file example.nix
installing 'example'
$ ls ~/.nix-profile
foo-file
bar-file
manifest.nix
```
Adding `meta.outputsToInstall` to that derivation will make `nix-env`only install files from the specified outputs.
Adding `meta.outputsToInstall` to that derivation will make `nix-env` only install files from the specified outputs.
The script's file name is passed as the first argument to the interpreter specified by the `-i` flag.
Aside from the very first line, which is a directive to the operating system, the additional `#! nix-shell` lines do not need to be at the beginning of the file.
This allows wrapping them in block comments for languages where `#` does not start a comment, such as ECMAScript, Erlang, PHP, or Ruby.
`nix-store --export` - export store paths to a Nix Archive
`nix-store --export` - export store paths to a [Nix Archive]
## Synopsis
@@ -8,16 +8,22 @@
## Description
The operation `--export` writes a serialisation of the specified store
paths to standard output in a format that can be imported into another
Nix store with `nix-store --import`. This is like `nix-store
--dump`, 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).
The operation `--export` writes a serialisation of the given [store objects](@docroot@/glossary.md#gloss-store-object) to standard output in a format that can be imported into another [Nix store](@docroot@/store/index.md) with [`nix-store --import`](./import.md).
This command does not produce a *closure* 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.
> **Warning**
>
> This command *does not* produce a [closure](@docroot@/glossary.md#gloss-closure) of the specified store paths.
> Trying to import a store object that refers to store paths not available in the target Nix store will fail.
>
> Use [`nix-store --query`](@docroot@/command-ref/nix-store/query.md) to obtain the closure of a store path.
This command is different from [`nix-store --dump`](./dump.md), which produces a [Nix archive](@docroot@/glossary.md#gloss-nar) that *does not* contain the set of [references](@docroot@/glossary.md#gloss-reference) of a given store path.
> **Note**
>
> For efficient transfer of closures to remote machines over SSH, use [`nix-copy-closure`](@docroot@/command-ref/nix-copy-closure.md).
The operation `--import` reads a serialisation of a set of store paths
produced by `nix-store --export` 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.
The operation `--import` reads a serialisation of a set of [store objects](@docroot@/glossary.md#gloss-store-object) produced by [`nix-store --export`](./export.md) from standard input, and adds those store objects to the specified [Nix store](@docroot@/store/index.md).
Paths that already exist in the target Nix store are ignored.
If a path [refers](@docroot@/glossary.md#gloss-reference) to another path that doesn’t exist in the target Nix store, the import fails.
> **Note**
>
> For efficient transfer of closures to remote machines over SSH, use [`nix-copy-closure`](@docroot@/command-ref/nix-copy-closure.md).
{{#include ./opt-common.md}}
{{#include ../opt-common.md}}
{{#include ../env-common.md}}
# Examples
> **Example**
>
> Given a closure of GNU Hello as a file:
>
> ```shell-session
> $ storePath="$(nix-build '<nixpkgs>' -I nixpkgs=channel:nixpkgs-unstable -A hello --no-out-link)"
> Import the closure into a [remote SSH store](@docroot@/store/types/ssh-store.md) using the [`--store`](@docroot@/command-ref/conf-file.md#conf-store) option:
@@ -37,7 +37,7 @@ Most Nix commands accept the following command-line options:
Print even more informational messages.
-`4` “Debug”
Print debug information.
-`5` “Vomit”
@@ -143,7 +143,7 @@ Most Nix commands accept the following command-line options:
This option is accepted by `nix-env`, `nix-instantiate`, `nix-shell` and `nix-build`.
When evaluating Nix expressions, the expression evaluator will automatically try to call functions that it encounters.
It can automatically call functions for which every argument has a [default value](@docroot@/language/constructs.md#functions) (e.g., `{ argName ? defaultValue }: ...`).
It can automatically call functions for which every argument has a [default value](@docroot@/language/syntax.md#functions) (e.g., `{ argName ? defaultValue }: ...`).
With `--arg`, you can also call functions that have arguments without a default value (or override a default value).
That is, if the evaluator encounters a function with an argument named *name*, it will call it with value *value*.
@@ -187,11 +187,12 @@ Most Nix commands accept the following command-line options:
For `nix-shell`, this option is commonly used to give you a shell in which you can build the packages returned by the expression.
If you want to get a shell which contain the *built* packages ready for use, give your expression to the `nix-shell --packages ` convenience flag instead.
Add an entry to the [Nix expression search path](@docroot@/command-ref/conf-file.md#conf-nix-path).
Add an entry to the list of search paths used to resolve [lookup paths](@docroot@/language/constructs/lookup-path.md).
This option may be given multiple times.
Paths added through `-I` take precedence over [`NIX_PATH`](@docroot@/command-ref/env-common.md#env-NIX_PATH).
Paths added through `-I` take precedence over the [`nix-path` configuration setting](@docroot@/command-ref/conf-file.md#conf-nix-path) and the [`NIX_PATH` environment variable](@docroot@/command-ref/env-common.md#env-NIX_PATH).
This section provides some notes on how to hack on Nix. To get the
latest version of Nix from GitHub:
This section provides some notes on how to start hacking on Nix.
To get the latest version of Nix from GitHub:
```console
$ git clone https://github.com/NixOS/nix.git
$ cd nix
```
The following instructions assume you already have some version of Nix installed locally, so that you can use it to set up the development environment. If you don't have it installed, follow the [installation instructions].
To build all dependencies and start a shell in which all environment variables are set up so that those dependencies can be found:
```console
$ nix develop
```
This shell also adds `./outputs/bin/nix` to your `$PATH` so you can run `nix` immediately after building it.
To get a shell with one of the other [supported compilation environments](#compilation-environments):
```console
$ nix develop .#native-clangStdenvPackages
```
> **Note**
>
> Use `ccacheStdenv` to drastically improve rebuild time.
> By default, [ccache](https://ccache.dev) keeps artifacts in `~/.cache/ccache/`.
> The following instructions assume you already have some version of Nix installed locally, so that you can use it to set up the development environment.
> If you don't have it installed, follow the [installation instructions](../installation/index.md).
To build Nix itself in this shell:
```console
[nix-shell]$ autoreconfPhase
[nix-shell]$ configurePhase
[nix-shell]$ make -j $NIX_BUILD_CORES
```
To install it in `$(pwd)/outputs` and test it:
```console
[nix-shell]$ make install
[nix-shell]$ make installcheck check -j $NIX_BUILD_CORES
[nix-shell]$ nix --version
nix (Nix) 2.12
```
For more information on running and filtering tests, see
[`testing.md`](./testing.md).
To build a release version of Nix for the current operating system and CPU architecture:
```console
$ nix build
```
You can also build Nix for one of the [supported platforms](#platforms).
## Building Nix
To build all dependencies and start a shell in which all environment variables are set up so that those dependencies can be found:
@@ -111,6 +56,60 @@ $ nix-build
You can also build Nix for one of the [supported platforms](#platforms).
## Building Nix with flakes
This section assumes you are using Nix with the [`flakes`] and [`nix-command`] experimental features enabled.
[binary format emulation]: https://nixos.org/manual/nixos/stable/options.html#opt-boot.binfmt.emulatedSystems
Given such a setup, executing the build only requires selecting the respective attribute.
@@ -166,7 +165,10 @@ or for Nix with the [`flakes`] and [`nix-command`] experimental features enabled
$ nix build .#packages.aarch64-linux.default
```
Cross-compiled builds are available for ARMv6 (`armv6l-linux`) and ARMv7 (`armv7l-linux`).
Cross-compiled builds are available for:
- `armv6l-linux`
- `armv7l-linux`
- `riscv64-linux`
Add more [system types](#system-type) to `crossSystems` in `flake.nix` to bootstrap Nix on unsupported platforms.
### Building for multiple platforms at once
@@ -196,7 +198,7 @@ In order to facilitate this, Nix has some support for being built out of tree
## System type
Nix uses a string with he following format to identify the *system type* or *platform* it runs on:
Nix uses a string with the following format to identify the *system type* or *platform* it runs on:
```
<cpu>-<os>[-<abi>]
@@ -258,10 +260,10 @@ See [supported compilation environments](#compilation-environments) and instruct
To use the LSP with your editor, you first need to [set up `clangd`](https://clangd.llvm.org/installation#project-setup) by running:
```console
make clean && bear -- make -j$NIX_BUILD_CORES default check install
make compile_commands.json
```
Configure your editor to use the `clangd` from the shell, either by running it inside the development shell, or by using [nix-direnv](https://github.com/nix-community/nix-direnv) and [the appropriate editor plugin](https://github.com/direnv/direnv/wiki#editor-integration).
Configure your editor to use the `clangd` from the `.#native-clangStdenvPackages` shell. You can do that either by running it inside the development shell, or by using [nix-direnv](https://github.com/nix-community/nix-direnv) and [the appropriate editor plugin](https://github.com/direnv/direnv/wiki#editor-integration).
> **Note**
>
@@ -269,80 +271,25 @@ Configure your editor to use the `clangd` from the shell, either by running it i
> Some other editors (e.g. Emacs, Vim) need a plugin to support LSP servers in general (e.g. [lsp-mode](https://github.com/emacs-lsp/lsp-mode) for Emacs and [vim-lsp](https://github.com/prabirshrestha/vim-lsp) for vim).
> Editor-specific setup is typically opinionated, so we will not cover it here in more detail.
## Add a release note
## Formatting and pre-commit hooks
`doc/manual/rl-next` contains release notes entries for all unreleased changes.
You may run the formatters as a one-off using:
User-visible changes should come with a release note.
### Add an entry
Here's what a complete entry looks like. The file name is not incorporated in the document.
```
---
synopsis: Basically a title
issues: 1234
prs: 1238
---
Here's one or more paragraphs that describe the change.
- It's markdown
- Add references to the manual using @docroot@
```console
make format
```
Significant changes should add the following header, which moves them to the top.
If you'd like to run the formatters before every commit, install the hooks:
```
significance: significant
pre-commit-hooks-install
```
<!-- Keep an eye on https://codeberg.org/fgaz/changelog-d/issues/1 -->
See also the [format documentation](https://github.com/haskell/cabal/blob/master/CONTRIBUTING.md#changelog).
This installs [pre-commit](https://pre-commit.com) using [cachix/git-hooks.nix](https://github.com/cachix/git-hooks.nix).
### Build process
When making a commit, pay attention to the console output.
If it fails, run `git add --patch` to approve the suggestions _and commit again_.
Releases have a precomputed `rl-MAJOR.MINOR.md`, and no `rl-next.md`.
@@ -389,88 +389,6 @@ colors, no emojis and using ASCII instead of Unicode symbols). The same should
happen when TTY is not detected on STDERR. We should not display progress /
status section, but only print warnings and errors.
## Returning future proof JSON
The schema of JSON output should allow for backwards compatible extension. This section explains how to achieve this.
Two definitions are helpful here, because while JSON only defines one "key-value"
object type, we use it to cover two use cases:
- **dictionary**: a map from names to value that all have the same type. In
C++ this would be a `std::map` with string keys.
- **record**: a fixed set of attributes each with their own type. In C++, this
would be represented by a `struct`.
It is best not to mix these use cases, as that may lead to incompatibilities when the schema changes. For example, adding a record field to a dictionary breaks consumers that assume all JSON object fields to have the same meaning and type.
This leads to the following guidelines:
- The top-level (root) value must be a record.
Otherwise, one can not change the structure of a command's output.
- The value of a dictionary item must be a record.
Otherwise, the item type can not be extended.
- List items should be records.
Otherwise, one can not change the structure of the list items.
If the order of the items does not matter, and each item has a unique key that is a string, consider representing the list as a dictionary instead. If the order of the items needs to be preserved, return a list of records.
- Streaming JSON should return records.
An example of a streaming JSON format is [JSON lines](https://jsonlines.org/), where each line represents a JSON value. These JSON values can be considered top-level values or list items, and they must be records.
### Examples
This is bad, because all keys must be assumed to be store types:
```json
{
"local": { ... },
"remote": { ... },
"http": { ... }
}
```
This is good, because the it is extensible at the root, and is somewhat self-documenting:
```json
{
"storeTypes": { "local": { ... }, ... },
"pluginSupport": true
}
```
While the dictionary of store types seems like a very complete response at first, a use case may arise that warrants returning additional information.
For example, the presence of plugin support may be crucial information for a client to proceed when their desired store type is missing.
The following representation is bad because it is not extensible:
```json
{ "outputs": [ "out" "bin" ] }
```
However, simply converting everything to records is not enough, because the order of outputs must be preserved:
```json
{ "outputs": { "bin": {}, "out": {} } }
```
The first item is the default output. Deriving this information from the outputs ordering is not great, but this is how Nix currently happens to work.
While it is possible for a JSON parser to preserve the order of fields, we can not rely on this capability to be present in all JSON libraries.
This representation is extensible and preserves the ordering:
@@ -5,4 +5,4 @@ Check the [contributing guide](https://github.com/NixOS/nix/blob/master/CONTRIBU
This chapter is a collection of guides for making changes to the code and documentation.
If you're not sure where to start, try to [compile Nix from source](./hacking.md) and consider [making improvements to documentation](./documentation.md).
If you're not sure where to start, try to [compile Nix from source](./building.md) and consider [making improvements to documentation](./documentation.md).
Nix consumes and produces JSON in a variety of contexts.
These guidelines ensure consistent practices for all our JSON interfaces, for ease of use, and so that experience in one part carries over to another.
## Extensibility
The schema of JSON input and output should allow for backwards compatible extension.
This section explains how to achieve this.
Two definitions are helpful here, because while JSON only defines one "key-value" object type, we use it to cover two use cases:
- **dictionary**: a map from names to value that all have the same type.
In C++ this would be a `std::map` with string keys.
- **record**: a fixed set of attributes each with their own type.
In C++, this would be represented by a `struct`.
It is best not to mix these use cases, as that may lead to incompatibilities when the schema changes.
For example, adding a record field to a dictionary breaks consumers that assume all JSON object fields to have the same meaning and type, and dictionary items with a colliding name can not be represented anymore.
This leads to the following guidelines:
- The top-level (root) value must be a record.
Otherwise, one can not change the structure of a command's output.
- The value of a dictionary item must be a record.
Otherwise, the item type can not be extended.
- List items should be records.
Otherwise, one can not change the structure of the list items.
If the order of the items does not matter, and each item has a unique key that is a string, consider representing the list as a dictionary instead.
If the order of the items needs to be preserved, return a list of records.
- Streaming JSON should return records.
An example of a streaming JSON format is [JSON lines](https://jsonlines.org/), where each line represents a JSON value.
These JSON values can be considered top-level values or list items, and they must be records.
### Examples
This is bad, because all keys must be assumed to be store types:
```json
{
"local":{...},
"remote":{...},
"http":{...}
}
```
This is good, because the it is extensible at the root, and is somewhat self-documenting:
```json
{
"storeTypes":{"local":{...},...},
"pluginSupport":true
}
```
While the dictionary of store types seems like a very complete response at first, a use case may arise that warrants returning additional information.
For example, the presence of plugin support may be crucial information for a client to proceed when their desired store type is missing.
The following representation is bad because it is not extensible:
```json
{"outputs":["out""bin"]}
```
However, simply converting everything to records is not enough, because the order of outputs must be preserved:
```json
{"outputs":{"bin":{},"out":{}}}
```
The first item is the default output. Deriving this information from the outputs ordering is not great, but this is how Nix currently happens to work.
While it is possible for a JSON parser to preserve the order of fields, we can not rely on this capability to be present in all JSON libraries.
This representation is extensible and preserves the ordering:
@@ -59,15 +59,15 @@ The unit tests are defined using the [googletest] and [rapidcheck] frameworks.
> …
> ```
The tests for each Nix library (`libnixexpr`, `libnixstore`, etc..) live inside a directory `tests/unit/${library_name_without-nix}`.
Given a interface (header) and implementation pair in the original library, say, `src/libexpr/value/context.{hh,cc}`, we write tests for it in `tests/unit/libexpr/tests/value/context.cc`, and (possibly) declare/define additional interfaces for testing purposes in `tests/unit/libexpr-support/tests/value/context.{hh,cc}`.
The tests for each Nix library (`libnixexpr`, `libnixstore`, etc..) live inside a directory `src/${library_name_without-nix}-test`.
Given an interface (header) and implementation pair in the original library, say, `src/libexpr/value/context.{hh,cc}`, we write tests for it in `src/nix-expr-tests/value/context.cc`, and (possibly) declare/define additional interfaces for testing purposes in `src/nix-expr-test-support/tests/value/context.{hh,cc}`.
Data for unit tests is stored in a `data` subdir of the directory for each unit test executable.
For example, `libnixstore` code is in `src/libstore`, and its test data is in `tests/unit/libstore/data`.
The path to the `tests/unit/data` directory is passed to the unit test executable with the environment variable `_NIX_TEST_UNIT_DATA`.
For example, `libnixstore` code is in `src/libstore`, and its test data is in `src/nix-store-tests/data`.
The path to the `src/${library_name_without-nix}-test/data` directory is passed to the unit test executable with the environment variable `_NIX_TEST_UNIT_DATA`.
Note that each executable only gets the data for its tests.
The unit test libraries are in `tests/unit/${library_name_without-nix}-lib`.
The unit test libraries are in `src/${library_name_without-nix}-test-support`.
All headers are in a `tests` subdirectory so they are included with `#include "tests/"`.
The use of all these separate directories for the unit tests might seem inconvenient, as for example the tests are not "right next to" the part of the code they are testing.
@@ -76,8 +76,25 @@ there is no risk of any build-system wildcards for the library accidentally pick
### Running tests
You can run the whole testsuite with `make check`, or the tests for a specific component with `make libfoo-tests_RUN`.
Finer-grained filtering is also possible using the [--gtest_filter](https://google.github.io/googletest/advanced.html#running-a-subset-of-the-tests) command-line option, orthe `GTEST_FILTER` environment variable, e.g. `GTEST_FILTER='ErrorTraceTest.*' make check`.
You can run the whole testsuite with `meson test` from the Meson build directory, or the tests for a specific component with `meson test nix-store-tests`.
A environment variables that Google Test accepts are also worth knowing:
@@ -252,13 +271,30 @@ Regressions are caught, and improvements always show up in code review.
To ensure that characterisation testing doesn't make it harder to intentionally change these interfaces, there always must be an easy way to regenerate the expected output, as we do with `_NIX_TEST_ACCEPT=1`.
### Running functional tests on NixOS
We run the functional tests not just in the build, but also in VM tests.
This helps us ensure that Nix works correctly on NixOS, and environments that have similar characteristics that are hard to reproduce in a build environment.
The recommended way to run these tests during development is:
The `quickBuild` attribute configures the test to use a `nix` package that's built without integration tests, so that you can iterate on the tests without performing recompilations due to the changed sources for `installCheck`.
Generally, this build is sufficient, but in nightly or CI we also test the attributes `functional_root` and `functional_trusted`, in which the test suite is run with different levels of authorization.
## Integration tests
The integration tests are defined in the Nix flake under the `hydraJobs.tests` attribute.
These tests include everything that needs to interact with external services or run Nix in a non-trivial distributed setup.
Because these tests are expensive and require more than what the standard github-actions setup provides, they only run on the master branch (on <https://hydra.nixos.org/jobset/nix/master>).
You can run them manually with `nix build .#hydraJobs.tests.{testName}` or `nix-build -A hydraJobs.tests.{testName}`
You can run them manually with `nix build .#hydraJobs.tests.{testName}` or `nix-build -A hydraJobs.tests.{testName}`.
If you are testing a build of `nix` that you haven't compiled yet, you may iterate faster by appending the `quickBuild` attribute: `nix build .#hydraJobs.tests.{testName}.quickBuild`.
Software Heritage's writing on [*Intrinsic and Extrinsic identifiers*](https://www.softwareheritage.org/2020/07/09/intrinsic-vs-extrinsic-identifiers) is also a good introduction to the value of content-addressing over other referencing schemes.
Besides content addressing, the Nix store also uses [input addressing](#gloss-input-addressed-store-object).
- [derivation]{#gloss-derivation}
A description of a build task. The result of a derivation is a
@@ -37,7 +56,7 @@
This can be achieved by:
- Fetching a pre-built [store object] from a [substituter]
- Running the [`builder`](@docroot@/language/derivations.md#attr-builder) executable as specified in the corresponding [derivation]
- Delegating to a [remote builder](@docroot@/advanced-topics/distributed-builds.html) and retrieving the outputs
- Delegating to a [remote machine](@docroot@/command-ref/conf-file.md#conf-builders) and retrieving the outputs
<!-- TODO: link [running] to build process page, #8888 -->
See [`nix-store --realise`](@docroot@/command-ref/nix-store/realise.md) for a detailed description of the algorithm.
A [derivation] where a cryptographic hash of the [output] is determined in advance using the [`outputHash`](./language/advanced-attributes.md#adv-attr-outputHash) attribute, and where the [`builder`](@docroot@/language/derivations.md#attr-builder) executable has access to the network.
- [store]{#gloss-store}
A collection of store objects, with operations to manipulate that collection.
See [Nix store](./store/index.md) for details.
A collection of [store objects][store object], with operations to manipulate that collection.
See [Nix Store](./store/index.md) for details.
There are many types of stores.
See [`nix help-stores`](@docroot@/command-ref/new-cli/nix3-help-stores.md) for a complete list.
From the perspective of the location where Nix is invoked, the Nix store can be referred to _local_ or _remote_.
Only a [local store]{#gloss-local-store} exposes a location in the file system of the machine where Nix is invoked that allows access to store objects, typically `/nix/store`.
Local stores can be used for building [derivations](#gloss-derivation).
See [Local Store](@docroot@/command-ref/new-cli/nix3-help-stores.md#local-store) for details.
There are many types of stores, see [Store Types](./store/types/index.md) for details.
[store]: #gloss-store
[local store]: #gloss-local-store
- [chroot store]{#gloss-chroot-store}
A [local store] whose canonical path is anything other than `/nix/store`.
- [binary cache]{#gloss-binary-cache}
@@ -87,7 +94,7 @@
- [store path]{#gloss-store-path}
The location of a [store object](@docroot@/store/index.md#store-object) in the file system, i.e., an immediate child of the Nix store directory.
The location of a [store object] in the file system, i.e., an immediate child of the Nix store directory.
> **Example**
>
@@ -97,7 +104,7 @@
[store path]: #gloss-store-path
- [file system object]{#gloss-store-object}
- [file system object]{#gloss-file-system-object}
The Nix data model for representing simplified file system data.
@@ -129,9 +136,12 @@
- [content-addressed store object]{#gloss-content-addressed-store-object}
A [store object] whose [store path] is determined by its contents.
A [store object] which is [content-addressed](#gloss-content-address),
i.e. whose [store path] is determined by its contents.
This includes derivations, the outputs of [content-addressed derivations](#gloss-content-addressed-derivation), and the outputs of [fixed-output derivations](#gloss-fixed-output-derivation).
See [Content-Addressing Store Objects](@docroot@/store/store-object/content-address.md) for details.
- [substitute]{#gloss-substitute}
A substitute is a command invocation stored in the [Nix database] that
@@ -158,7 +168,7 @@
- [impure derivation]{#gloss-impure-derivation}
[An experimental feature](#@docroot@/contributing/experimental-features.md#xp-feature-impure-derivations) that allows derivations to be explicitly marked as impure,
[An experimental feature](#@docroot@/development/experimental-features.md#xp-feature-impure-derivations) that allows derivations to be explicitly marked as impure,
so that they are always rebuilt, and their outputs not reused by subsequent calls to realise them.
- [Nix database]{#gloss-nix-database}
@@ -226,6 +236,20 @@
[output path]: #gloss-output-path
- [output closure]{#gloss-output-closure}\
The [closure] of an [output path]. It only contains what is [reachable] from the output.
- [deriving path]{#gloss-deriving-path}
Deriving paths are a way to refer to [store objects][store object] that ar not yet [realised][realise].
This is necessary because, in general and particularly for [content-addressed derivations][content-addressed derivation], the [output path] of an [output] is not known in advance.
There are two forms:
- *constant*: just a [store path]
It can be made [valid][validity] by copying it into the store: from the evaluator, command line interface or another store.
- *output*: a pair of a [store path] to a [derivation] and an [output] name.
- [deriver]{#gloss-deriver}
The [store derivation] that produced an [output path].
@@ -243,6 +267,7 @@
- All paths in the store path's [closure] are valid.
See [installables](./command-ref/new-cli/nix.md#installables) for [`nix` commands](./command-ref/new-cli/nix.md) (experimental) for details.
- [NAR]{#gloss-nar}
- [Nix Archive (NAR)]{#gloss-nar}
A *N*ix *AR*chive. This is a serialisation of a path in the Nix
store. It can contain regular files, directories and symbolic
links. NARs are generated and unpacked using `nix-store --dump`
and `nix-store --restore`.
See [Nix Archive](store/file-system-object/content-address.html#serial-nix-archive) for details.
- [`∅`]{#gloss-emtpy-set}
The empty set symbol. In the context of profile history, this denotes a package is not present in a particular version of the profile.
@@ -285,7 +312,7 @@
- [package attribute set]{#package-attribute-set}
An [attribute set](@docroot@/language/values.md#attribute-set) containing the attribute `type = "derivation";` (derivation for historical reasons), as well as other attributes, such as
An [attribute set](@docroot@/language/types.md#attribute-set) containing the attribute `type = "derivation";` (derivation for historical reasons), as well as other attributes, such as
- attributes that refer to the files of a [package], typically in the form of [derivation outputs](#output),
- attributes that declare something about how the package is supposed to be installed or used,
- other metadata or arbitrary attributes.
@@ -298,16 +325,35 @@
See [String interpolation](./language/string-interpolation.md) for details.
The location from which relative paths are resolved.
- For expressions in a file, the base directory is the directory containing that file.
This is analogous to the directory of a [base URL](https://datatracker.ietf.org/doc/html/rfc1808#section-3.3).
<!-- which is sufficient for resolving non-empty URLs -->
<!--
The wording here may look awkward, but it's for these reasons:
* "with --expr": it's a flag, and not an option with an accompanying value
* "written in": the expression itself must be written as an argument,
whereas the more natural "passed as an argument" allows an interpretation
where the expression could be passed by file name.
-->
- For expressions written in command line arguments with [`--expr`](@docroot@/command-ref/opt-common.html#opt-expr), the base directory is the current working directory.
> Writing to the [local store](@docroot@/store/types/local-store.md) with a newer version of Nix, for example by building derivations with [`nix-build`](@docroot@/command-ref/nix-build.md) or [`nix-store --realise`](@docroot@/command-ref/nix-store/realise.md), may change the database schema!
> Reverting to an older version of Nix may therefore require purging the store database before it can be used.
These attributes declare that the derivation is a so-called
*fixed-output derivation*, which means that a cryptographic hash of
the output is already known in advance. When the build of a
fixed-output derivation finishes, Nix computes the cryptographic
hash of the output and compares it to the hash declared with these
attributes. If there is a mismatch, the build fails.
These attributes declare that the derivation is a so-called *fixed-output derivation* (FOD), which means that a cryptographic hash of the output is already known in advance.
As opposed to regular derivations, the [`builder`] executable of a fixed-output derivation has access to the network.
Nix computes a cryptographic hash of its output and compares that to the hash declared with these attributes.
If there is a mismatch, the derivation fails.
The rationale for fixed-output derivations is derivations such as
those produced by the `fetchurl` function. This function downloads a
@@ -188,38 +187,49 @@ Derivations can declare some infrequently used optional attributes.
}
```
The `outputHashAlgo` attribute specifies the hash algorithm used to
compute the hash. It can currently be `"sha1"`, `"sha256"` or
`"sha512"`.
The `outputHash` attribute must be a string containing the hash in either hexadecimal or "nix32" encoding, or following the format for integrity metadata as defined by [SRI](https://www.w3.org/TR/SRI/).
The "nix32" encoding is an adaptation of base-32 encoding.
The [`convertHash`](@docroot@/language/builtins.md#builtins-convertHash) function shows how to convert between different encodings, and the [`nix-hash` command](../command-ref/nix-hash.md) has information about obtaining the hash for some contents, as well as converting to and from encodings.
The `outputHashAlgo` attribute specifies the hash algorithm used to compute the hash.
It can currently be `"sha1"`, `"sha256"`, `"sha512"`, or `null`.
`outputHashAlgo` can only be `null` when `outputHash` follows the SRI format.
The `outputHashMode` attribute determines how the hash is computed.
It must be one of the following two values:
It must be one of the following values:
- `"flat"`\
The output must be a non-executable regular file. If it isn’t,
the build fails. The hash is simply computed over the contents
of that file (so it’s equal to what Unix commands like
If this attribute is set to `true` and [distributed building is enabled](../advanced-topics/distributed-builds.md), then, if possible, the derivation will be built locally instead of being forwarded to a remote machine.
If this attribute is set to `true` and [distributed building is enabled](@docroot@/command-ref/conf-file.md#conf-builders), then, if possible, the derivation will be built locally instead of being forwarded to a remote machine.
This is useful for derivations that are cheapest to build locally.
@@ -268,7 +278,9 @@ Derivations can declare some infrequently used optional attributes.
> **Note**
>
> If set to `false`, the [`builder`](./derivations.md#attr-builder) should be able to run on the system type specified in the [`system` attribute](./derivations.md#attr-system), since the derivation cannot be substituted.
> If set to `false`, the [`builder`] should be able to run on the system type specified in the [`system` attribute](./derivations.md#attr-system), since the derivation cannot be substituted.
If the special attribute `__structuredAttrs` is set to `true`, the other derivation
@@ -290,6 +302,12 @@ Derivations can declare some infrequently used optional attributes.
(associative) arrays. For example, the attribute `hardening.format = true`
ends up as the Bash associative array element `${hardening[format]}`.
> **Warning**
>
> If set to `true`, other advanced attributes such as [`allowedReferences`](#adv-attr-allowedReferences), [`allowedReferences`](#adv-attr-allowedReferences), [`allowedRequisites`](#adv-attr-allowedRequisites),
[`disallowedReferences`](#adv-attr-disallowedReferences) and [`disallowedRequisites`](#adv-attr-disallowedRequisites), maxSize, and maxClosureSize.
will have no effect.
- [`outputChecks`]{#adv-attr-outputChecks}\
When using [structured attributes](#adv-attr-structuredAttrs), the `outputChecks`
attribute allows defining checks per-output.
@@ -299,7 +317,7 @@ Derivations can declare some infrequently used optional attributes.
[`disallowedReferences`](#adv-attr-disallowedReferences) and [`disallowedRequisites`](#adv-attr-disallowedRequisites),
the following attributes are available:
- `maxSize` defines the maximum size of the resulting [store object](../glossary.md#gloss-store-object).
- `maxSize` defines the maximum size of the resulting [store object](@docroot@/store/store-object.md).
- `maxClosureSize` defines the maximum size of the output's closure.
- `ignoreSelfRefs` controls whether self-references should be considered when
checking for allowed references/requisites.
@@ -351,3 +369,7 @@ Derivations can declare some infrequently used optional attributes.
```
ensures that the derivation can only be built on a machine with the `kvm` feature.
When defining an [attribute set](./values.md#attribute-set) or in a [let-expression](#let-expressions) it is often convenient to copy variables from the surrounding lexical scope (e.g., when you want to propagate attributes).
This can be shortened using the `inherit` keyword.
Example:
```nix
letx=123;in
{
inheritx;
y=456;
}
```
is equivalent to
```nix
letx=123;in
{
x=x;
y=456;
}
```
and both evaluate to `{ x = 123; y = 456; }`.
> **Note**
>
> This works because `x` is added to the lexical scope by the `let` construct.
It is also possible to inherit attributes from another attribute set.
Example:
In this fragment from `all-packages.nix`,
```nix
graphviz=(import../tools/graphics/graphviz){
inheritfetchurlstdenvlibpnglibjpegexpatx11yacc;
inherit(xorg)libXaw;
};
xorg={
libX11=...;
libXaw=...;
...
}
libpng=...;
libjpg=...;
...
```
the set used in the function call to the function defined in
`../tools/graphics/graphviz` inherits a number of variables from the
surrounding scope (`fetchurl` ... `yacc`), but also inherits `libXaw`
(the X Athena Widgets) from the `xorg` set.
Summarizing the fragment
```nix
...
inheritxyz;
inherit(src-set)abc;
...
```
is equivalent to
```nix
...
x=x;y=y;z=z;
a=src-set.a;b=src-set.b;c=src-set.c;
...
```
when used while defining local variables in a let-expression or while
defining a set.
In a `let` expression, `inherit` can be used to selectively bring specific attributes of a set into scope. For example
```nix
let
x={a=1;b=2;};
inherit(builtins)attrNames;
in
{
names=attrNamesx;
}
```
is equivalent to
```nix
let
x={a=1;b=2;};
in
{
names=builtins.attrNamesx;
}
```
both evaluate to `{ names = [ "a" "b" ]; }`.
## Functions
Functions have the following form:
```nix
pattern:body
```
The pattern specifies what the argument of the function must look like,
and binds variables in the body to (parts of) the argument. There are
three kinds of patterns:
- If a pattern is a single identifier, then the function matches any
argument. Example:
```nix
let negate = x: !x;
concat = x: y: x + y;
in if negate true then concat "foo" "bar" else ""
```
Note that `concat` is a function that takes one argument and returns
a function that takes another argument. This allows partial
parameterisation (i.e., only filling some of the arguments of a
function); e.g.,
```nix
map (concat "foo") [ "bar" "bla" "abc" ]
```
evaluates to `[ "foobar" "foobla" "fooabc" ]`.
- A *set pattern* of the form `{ name1, name2, …, nameN }` matches a
set containing the listed attributes, and binds the values of those
attributes to variables in the function body. For example, the
function
```nix
{ x, y, z }: z + y + x
```
can only be called with a set containing exactly the attributes `x`,
`y` and `z`. No other attributes are allowed. If you want to allow
additional arguments, you can use an ellipsis (`...`):
```nix
{ x, y, z, ... }: z + y + x
```
This works on any set that contains at least the three named
attributes.
It is possible to provide *default values* for attributes, in
which case they are allowed to be missing. A default value is
specified by writing `name ? e`, where *e* is an arbitrary
expression. For example,
```nix
{ x, y ? "foo", z ? "bar" }: z + y + x
```
specifies a function that only requires an attribute named `x`, but
optionally accepts `y` and `z`.
- An `@`-pattern provides a means of referring to the whole value
being matched:
```nix
args@{ x, y, z, ... }: z + y + x + args.a
```
but can also be written as:
```nix
{ x, y, z, ... } @ args: z + y + x + args.a
```
Here `args` is bound to the argument *as passed*, which is further
matched against the pattern `{ x, y, z, ... }`.
The `@`-pattern makes mainly sense with an ellipsis(`...`) as
you can access attribute names as `a`, using `args.a`, which was
given as an additional attribute to the function.
> **Warning**
>
> `args@` binds the name `args` to the attribute set that is passed to the function.
> In particular, `args` does *not* include any default values specified with `?` in the function's set pattern.
>
> For instance
>
> ```nix
> let
> f = args@{ a ? 23, ... }: [ a args ];
> in
> f {}
> ```
>
> is equivalent to
>
> ```nix
> let
> f = args @ { ... }: [ (args.a or 23) args ];
> in
> f {}
> ```
>
> and both expressions will evaluate to:
>
> ```nix
> [ 23 {} ]
> ```
Note that functions do not have names. If you want to give them a name,
you can bind them to an attribute, e.g.,
```nix
let concat = { x, y }: x + y;
in concat { x = "foo"; y = "bar"; }
```
## Conditionals
Conditionals look like this:
```nix
if e1 then e2 else e3
```
where *e1* is an expression that should evaluate to a Boolean value
(`true` or `false`).
## Assertions
Assertions are generally used to check that certain requirements on or
between features and dependencies hold. They look like this:
```nix
assert e1; e2
```
where *e1* is an expression that should evaluate to a Boolean value. If
it evaluates to `true`, *e2* is returned; otherwise expression
evaluation is aborted and a backtrace is printed.
Here is a Nix expression for the Subversion package that shows how
A lookup path is an identifier with an optional path suffix that resolves to a [path value](@docroot@/language/values.md#type-path) if the identifier matches a search path entry.
A lookup path is an identifier with an optional path suffix that resolves to a [path value](@docroot@/language/types.md#type-path) if the identifier matches a search path entry.
The value of a lookup path is determined by [`builtins.nixPath`](@docroot@/language/builtin-constants.md#builtins-nixPath).
The value of a lookup path is determined by [`builtins.nixPath`](@docroot@/language/builtins.md#builtins-nixPath).
See [`builtins.findFile`](@docroot@/language/builtins.md#builtins-findFile) for details on lookup path resolution.
@@ -64,9 +64,9 @@ It outputs an attribute set, and produces a [store derivation] as a side effect
> }
> ```
>
> [`builtins.currentSystem`](@docroot@/language/builtin-constants.md#builtins-currentSystem) has the value of the [`system` configuration option], and defaults to the system type of the current Nix installation.
> [`builtins.currentSystem`](@docroot@/language/builtins.md#builtins-currentSystem) has the value of the [`system` configuration option], and defaults to the system type of the current Nix installation.
Path to an executable that will perform the build.
@@ -113,7 +113,7 @@ It outputs an attribute set, and produces a [store derivation] as a side effect
### Optional
- [`args`]{#attr-args} ([List](@docroot@/language/values.md#list) of [String](@docroot@/language/values.md#type-string))
- [`args`]{#attr-args} ([List](@docroot@/language/types.md#list) of [String](@docroot@/language/types.md#type-string))
Default: `[ ]`
@@ -132,7 +132,7 @@ It outputs an attribute set, and produces a [store derivation] as a side effect
> };
> ```
- [`outputs`]{#attr-outputs} ([List](@docroot@/language/values.md#list) of [String](@docroot@/language/values.md#type-string))
- [`outputs`]{#attr-outputs} ([List](@docroot@/language/types.md#list) of [String](@docroot@/language/types.md#type-string))
Default: `[ "out" ]`
@@ -141,7 +141,7 @@ It outputs an attribute set, and produces a [store derivation] as a side effect
By default, a derivation produces a single output called `out`.
However, derivations can produce multiple outputs.
This allows the associated [store objects](@docroot@/glossary.md#gloss-store-object) and their [closures](@docroot@/glossary.md#gloss-closure) to be copied or garbage-collected separately.
This allows the associated [store objects](@docroot@/store/store-object.md) and their [closures](@docroot@/glossary.md#gloss-closure) to be copied or garbage-collected separately.
An *identifier* is an [ASCII](https://en.wikipedia.org/wiki/ASCII) character sequence that:
- Starts with a letter (`a-z`, `A-Z`) or underscore (`_`)
- Can contain any number of:
- Letters (`a-z`, `A-Z`)
- Digits (`0-9`)
- Underscores (`_`)
- Apostrophes (`'`)
- Hyphens (`-`)
- Is not one of the [keywords](#keywords)
> **Syntax**
>
> *identifier* ~ `[A-Za-z_][A-Za-z0-9_'-]*`
# Names
A name can be an [identifier](#identifier) or a [string literal](./syntax.md#string-literal).
> **Syntax**
>
> *name* → *identifier* | *string*
Names are used in [attribute sets](./syntax.md#attrs-literal), [`let` bindings](./syntax.md#let-expressions), and [`inherit`](./syntax.md#inheriting attributes).
# Keywords
These keywords are reserved and cannot be used as [identifiers](#identifiers):
- [`assert`](./syntax.md#assertions)
- [`else`][if]
- [`if`][if]
- [`in`][let]
- [`inherit`](./syntax.md#inheriting-attributes)
- [`let`][let]
- [`or`](./operators.md#attribute-selection) (see note)
- [`rec`](./syntax.md#recursive-sets)
- [`then`][if]
- [`with`](./syntax.md#with-expressions)
[if]: ./syntax.md#conditionals
[let]: ./syntax.md#let-expressions
> **Note**
>
> The Nix language evaluator currently allows `or` to be used as a name in some contexts, for backwards compatibility reasons.
> Users are advised not to rely on this.
>
> There are long-standing issues with how `or` is parsed as a name, which can't be resolved without making a breaking change to the language.
The value of a Nix expression can depend on the contents of a [store object](@docroot@/glossary.md#gloss-store-object).
The value of a Nix expression can depend on the contents of a [store object].
Passing an expression `expr` that evaluates to a [store path](@docroot@/glossary.md#gloss-store-path) to any built-in function which reads from the filesystem constitutes Import From Derivation (IFD):
[store object]: @docroot@/store/store-object.md
Passing an expression `expr` that evaluates to a [store path](@docroot@/store/store-path.md) to any built-in function which reads from the filesystem constitutes Import From Derivation (IFD):
The Nix language is designed for conveniently creating and composing *derivations*– precise descriptions of how contents of existing files are used to derive new files.
It is:
> **Tip**
>
> These pages are written as a reference.
> If you are learning Nix, nix.dev has a good [introduction to the Nix language](https://nix.dev/tutorials/nix-language).
The language is:
- *domain-specific*
@@ -47,7 +53,7 @@ This is an incomplete overview of language features, by example.
@@ -124,7 +142,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
Null value
[Null](@docroot@/language/types.md#type-null) value
</td>
</tr>
@@ -136,7 +154,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
An integer
An [integer](@docroot@/language/types.md#type-int)
</td>
</tr>
@@ -148,7 +166,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
A floating point number
A [floating point number](@docroot@/language/types.md#type-float)
</td>
</tr>
@@ -160,7 +178,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
An absolute path
An absolute [path](@docroot@/language/types.md#type-path)
</td>
</tr>
@@ -172,7 +190,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
A path relative to the file containing this Nix expression
A [path](@docroot@/language/types.md#type-path) relative to the file containing this Nix expression
</td>
</tr>
@@ -184,7 +202,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
A home path. Evaluates to the `"<user's home directory>/.config"`.
A home [path](@docroot@/language/types.md#type-path). Evaluates to the `"<user's home directory>/.config"`.
</td>
</tr>
@@ -196,7 +214,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
Search path for Nix files. Value determined by [`$NIX_PATH` environment variable](../command-ref/env-common.md#env-NIX_PATH).
A [lookup path](@docroot@/language/constructs/lookup-path.md) for Nix files. Value determined by [`$NIX_PATH` environment variable](../command-ref/env-common.md#env-NIX_PATH).
</td>
</tr>
@@ -220,7 +238,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
A set with attributes named `x` and `y`
An [attribute set](@docroot@/language/types.md#attribute-set) with attributes named `x` and `y`
</td>
</tr>
@@ -244,7 +262,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
A recursive set, equivalent to `{ x = "foo"; y = "foobar"; }`
A [recursive set](@docroot@/language/syntax.md#recursive-sets), equivalent to `{ x = "foo"; y = "foobar"; }`.
</td>
</tr>
@@ -260,7 +278,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
Lists with three elements.
[Lists](@docroot@/language/types.md#list) with three elements.
</td>
</tr>
@@ -344,7 +362,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
Attribute selection (evaluates to `1`)
[Attribute selection](@docroot@/language/types.md#attribute-set) (evaluates to `1`)
</td>
</tr>
@@ -356,7 +374,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
Attribute selection with default (evaluates to `3`)
[Attribute selection](@docroot@/language/types.md#attribute-set) with default (evaluates to `3`)
</td>
</tr>
@@ -392,7 +410,7 @@ This is an incomplete overview of language features, by example.
@@ -452,7 +500,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
A function that expects an integer and returns it increased by 1
A [function](@docroot@/language/syntax.md#functions) that expects an integer and returns it increased by 1.
</td>
</tr>
@@ -464,7 +512,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
Curried function, equivalent to `x: (y: x + y)`. Can be used like a function that takes two arguments and returns their sum.
Curried [function](@docroot@/language/syntax.md#functions), equivalent to `x: (y: x + y)`. Can be used like a function that takes two arguments and returns their sum.
</td>
</tr>
@@ -476,7 +524,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
A function call (evaluates to 101)
A [function](@docroot@/language/syntax.md#functions) call (evaluates to 101)
</td>
</tr>
@@ -488,7 +536,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
A function bound to a variable and subsequently called by name (evaluates to 103)
A [function](@docroot@/language/syntax.md#functions) bound to a variable and subsequently called by name (evaluates to 103)
</td>
</tr>
@@ -500,7 +548,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
A function that expects a set with required attributes `x` and `y` and concatenates them
A [function](@docroot@/language/syntax.md#functions) that expects a set with required attributes `x` and `y` and concatenates them
</td>
</tr>
@@ -512,7 +560,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
A function that expects a set with required attribute `x` and optional `y`, using `"bar"` as default value for `y`
A [function](@docroot@/language/syntax.md#functions) that expects a set with required attribute `x` and optional `y`, using `"bar"` as default value for `y`
</td>
</tr>
@@ -524,7 +572,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
A function that expects a set with required attributes `x` and `y` and ignores any other attributes
A [function](@docroot@/language/syntax.md#functions) that expects a set with required attributes `x` and `y` and ignores any other attributes
</td>
</tr>
@@ -538,7 +586,7 @@ This is an incomplete overview of language features, by example.
</td>
<td>
A function that expects a set with required attributes `x` and `y`, and binds the whole set to `args`
A [function](@docroot@/language/syntax.md#functions) that expects a set with required attributes `x` and `y`, and binds the whole set to `args`
</td>
</tr>
@@ -562,7 +610,8 @@ This is an incomplete overview of language features, by example.
</td>
<td>
Load and return Nix expression in given file
Load and return Nix expression in given file.
See [import](@docroot@/language/builtins.md#builtins-import).
</td>
</tr>
@@ -574,7 +623,8 @@ This is an incomplete overview of language features, by example.
</td>
<td>
Apply a function to every element of a list (evaluates to `[ 2 4 6 ]`)
Apply a function to every element of a list (evaluates to `[ 2 4 6 ]`).
See [`map`](@docroot@/language/builtins.md#builtins-map).
</td>
</tr>
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