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MSYS2-packages/msys2-runtime/0006-Instead-of-creating-Cygwin-symlinks-use-deep-copy-by.patch
Johannes Schindelin 56b1ad3d0d msys2-runtime: Rebase to Cygwin v3.6.4 
This corresponds to https://github.com/msys2/msys2-runtime/pull/304

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2025-07-16 18:07:43 +02:00

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From 242443bf1f2cfabbcb0ea5202f1b5f7d196fd24c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=90=D0=BB=D0=B5=D0=BA=D1=81=D0=B5=D0=B8=CC=86=20=D0=9F?=
=?UTF-8?q?=D0=B0=D0=B2=D0=BB=D0=BE=D0=B2?= <alexey.pawlow@gmail.com>
Date: Sun, 14 Apr 2019 21:47:21 +0300
Subject: [PATCH 06/N] Instead of creating Cygwin symlinks, use deep copy by
default
The new `winsymlinks` mode `deepcopy` (which is made the default) lets
calls to `symlink()` create (deep) copies of the source file/directory.
This is necessary because unlike Cygwin, MSYS2 does not try to be its
own little ecosystem that lives its life separate from regular Win32
programs: the latter have _no idea_ about Cygwin-emulated symbolic links
(i.e. system files whose contents start with `!<symlink>\xff\xfe` and
the remainder consists of the NUL-terminated, UTF-16LE-encoded symlink
target).
To support Cygwin-style symlinks, the new mode `sysfile` is introduced.
Co-authored-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Co-authored-by: Jeremy Drake <github@jdrake.com>
---
winsup/cygwin/environ.cc | 4 +
winsup/cygwin/globals.cc | 3 +-
winsup/cygwin/path.cc | 252 +++++++++++++++++++++++++++++++++++++++
3 files changed, 258 insertions(+), 1 deletion(-)
diff --git a/winsup/cygwin/environ.cc b/winsup/cygwin/environ.cc
index b9f7e05..5fb3f53 100644
--- a/winsup/cygwin/environ.cc
+++ b/winsup/cygwin/environ.cc
@@ -88,6 +88,10 @@ set_winsymlinks (const char *buf)
else if (ascii_strncasematch (buf, "native", 6))
allow_winsymlinks = ascii_strcasematch (buf + 6, "strict")
? WSYM_nativestrict : WSYM_native;
+ else if (ascii_strncasematch (buf, "deepcopy", 8))
+ allow_winsymlinks = WSYM_deepcopy;
+ else
+ allow_winsymlinks = WSYM_sysfile;
}
/* The structure below is used to set up an array which is used to
diff --git a/winsup/cygwin/globals.cc b/winsup/cygwin/globals.cc
index d8e058f..b7e0e21 100644
--- a/winsup/cygwin/globals.cc
+++ b/winsup/cygwin/globals.cc
@@ -57,6 +57,7 @@ enum winsym_t
WSYM_nativestrict,
WSYM_nfs,
WSYM_sysfile,
+ WSYM_deepcopy
};
exit_states NO_COPY exit_state;
@@ -70,7 +71,7 @@ bool ignore_case_with_glob;
bool pipe_byte = true; /* Default to byte mode so that C# programs work. */
bool reset_com;
bool wincmdln;
-winsym_t allow_winsymlinks = WSYM_default;
+winsym_t allow_winsymlinks = WSYM_deepcopy;
bool disable_pcon;
bool winjitdebug = false;
diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
index 8ef347c..aae10fe 100644
--- a/winsup/cygwin/path.cc
+++ b/winsup/cygwin/path.cc
@@ -1722,6 +1722,173 @@ conv_path_list (const char *src, char *dst, size_t size,
/********************** Symbolic Link Support **************************/
+static int
+recursiveCopyCheckSymlink(PUNICODE_STRING src, bool& isdirlink)
+{
+ path_conv pc (src, PC_SYM_NOFOLLOW|PC_SYM_NOFOLLOW_REP);
+ if (pc.error)
+ {
+ set_errno (pc.error);
+ return -1;
+ }
+ isdirlink = pc.issymlink ();
+ return 0;
+}
+
+/*
+ Create a deep copy of src as dst, while avoiding descending in origpath.
+*/
+static int
+recursiveCopy (PUNICODE_STRING src, PUNICODE_STRING dst, USHORT origsrclen,
+ USHORT origdstlen, PWIN32_FIND_DATAW dHfile = NULL)
+{
+ HANDLE dH = INVALID_HANDLE_VALUE;
+ NTSTATUS status;
+ int srcpos = src->Length;
+ int dstpos = dst->Length;
+ int res = -1;
+ bool freedHfile = false;
+
+ if (!dHfile)
+ {
+ dHfile = (PWIN32_FIND_DATAW) cmalloc_abort (HEAP_STR, sizeof (*dHfile));
+ freedHfile = true;
+ }
+
+ debug_printf ("recursiveCopy (%S, %S)", src, dst);
+
+ /* Create the destination directory */
+ if (!CreateDirectoryExW (src->Buffer, dst->Buffer, NULL))
+ {
+ debug_printf ("CreateDirectoryExW(%S, %S, 0) failed", src, dst);
+ __seterrno ();
+ goto done;
+ }
+ /* Descend into the source directory */
+ if (src->Buffer[(src->Length - 1) / sizeof (WCHAR)] != L'\\')
+ {
+ status = RtlAppendUnicodeToString (src, L"\\*");
+ }
+ else
+ {
+ status = RtlAppendUnicodeToString (src, L"*");
+ srcpos -= sizeof (WCHAR);
+ }
+ if (!NT_SUCCESS (status))
+ {
+ __seterrno_from_nt_status (status);
+ goto done;
+ }
+ if (dst->Buffer[(dst->Length - 1) / sizeof (WCHAR)] != L'\\')
+ status = RtlAppendUnicodeToString (dst, L"\\");
+ else
+ dstpos -= sizeof (WCHAR);
+ if (!NT_SUCCESS (status))
+ {
+ __seterrno_from_nt_status (status);
+ goto done;
+ }
+
+ dH = FindFirstFileExW (src->Buffer, FindExInfoBasic, dHfile,
+ FindExSearchNameMatch, NULL,
+ FIND_FIRST_EX_LARGE_FETCH);
+ if (dH == INVALID_HANDLE_VALUE)
+ {
+ __seterrno ();
+ goto done;
+ }
+
+ do
+ {
+ bool isdirlink = false;
+ debug_printf ("dHfile: %W", dHfile->cFileName);
+ if (dHfile->cFileName[0] == L'.' &&
+ (!dHfile->cFileName[1] ||
+ (dHfile->cFileName[1] == L'.' && !dHfile->cFileName[2])))
+ continue;
+ /* Append the directory item filename to both source and destination */
+ src->Length = srcpos + sizeof (WCHAR);
+ dst->Length = dstpos + sizeof (WCHAR);
+ status = RtlAppendUnicodeToString (src, dHfile->cFileName);
+ if (!NT_SUCCESS (status))
+ {
+ __seterrno_from_nt_status (status);
+ goto done;
+ }
+ status = RtlAppendUnicodeToString (dst, dHfile->cFileName);
+ if (!NT_SUCCESS (status))
+ {
+ __seterrno_from_nt_status (status);
+ goto done;
+ }
+ debug_printf ("%S -> %S", src, dst);
+ if ((dHfile->dwFileAttributes &
+ (FILE_ATTRIBUTE_DIRECTORY|FILE_ATTRIBUTE_REPARSE_POINT)) ==
+ (FILE_ATTRIBUTE_DIRECTORY|FILE_ATTRIBUTE_REPARSE_POINT))
+ {
+ /* I was really hoping to avoid using path_conv in the recursion,
+ but maybe putting it in its own function will prevent it from
+ taking up space in the stack frame */
+ if (recursiveCopyCheckSymlink (src, isdirlink))
+ goto done;
+ }
+ if (isdirlink)
+ {
+ /* CreateDirectoryEx seems to "copy" directory reparse points, which
+ CopyFileEx can only do with a flag introduced in 19041. */
+ if (!CreateDirectoryExW (src->Buffer, dst->Buffer, NULL))
+ {
+ debug_printf ("CreateDirectoryExW(%S, %S, 0) failed", src, dst);
+ __seterrno ();
+ goto done;
+ }
+ }
+ else if (dHfile->dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
+ {
+ /* Recurse into the child directory */
+ /* avoids endless recursion */
+ if (src->Length <= origsrclen ||
+ (!wcsncmp (src->Buffer, dst->Buffer, origdstlen / sizeof (WCHAR)) &&
+ (!src->Buffer[origdstlen / sizeof (WCHAR)] ||
+ iswdirsep(src->Buffer[origdstlen / sizeof (WCHAR)]))))
+ {
+ set_errno (ELOOP);
+ goto done;
+ }
+ if (recursiveCopy (src, dst, origsrclen, origdstlen, dHfile))
+ goto done;
+ }
+ else
+ {
+ /* Just copy the file */
+ if (!CopyFileExW (src->Buffer, dst->Buffer, NULL, NULL, NULL,
+ COPY_FILE_COPY_SYMLINK))
+ {
+ __seterrno ();
+ goto done;
+ }
+ }
+ }
+ while (FindNextFileW (dH, dHfile));
+
+ if (GetLastError() != ERROR_NO_MORE_FILES)
+ {
+ __seterrno ();
+ goto done;
+ }
+ res = 0;
+
+done:
+
+ if (dH != INVALID_HANDLE_VALUE)
+ FindClose (dH);
+
+ if (freedHfile)
+ cfree (dHfile);
+
+ return res;
+}
+
/* Create a symlink from FROMPATH to TOPATH. */
extern "C" int
@@ -2045,6 +2212,84 @@ symlink_wsl (const char *oldpath, path_conv &win32_newpath)
return 0;
}
+int
+symlink_deepcopy (const char *oldpath, path_conv &win32_newpath)
+{
+ tmp_pathbuf tp;
+ path_conv win32_oldpath;
+
+ resolve_symlink_target (oldpath, win32_newpath, win32_oldpath);
+ if (win32_oldpath.error)
+ {
+ set_errno (win32_oldpath.error);
+ return -1;
+ }
+ if (win32_oldpath.isspecial ())
+ return -2;
+
+ /* MSYS copy file instead make symlink */
+ /* As a MSYS limitation, the source path must exist. */
+ if (!win32_oldpath.exists ())
+ {
+ set_errno (ENOENT);
+ return -1;
+ }
+
+ PUNICODE_STRING w_oldpath = win32_oldpath.get_nt_native_path ();
+ PUNICODE_STRING w_newpath = win32_newpath.get_nt_native_path ();
+ if (w_oldpath->Buffer[1] == L'?')
+ w_oldpath->Buffer[1] = L'\\';
+ if (w_newpath->Buffer[1] == L'?')
+ w_newpath->Buffer[1] = L'\\';
+ if (win32_oldpath.isdir ())
+ {
+ /* we need a larger UNICODE_STRING MaximumLength than
+ get_nt_native_path allocates for the recursive copy */
+ UNICODE_STRING u_oldpath, u_newpath;
+ RtlCopyUnicodeString (tp.u_get (&u_oldpath), w_oldpath);
+ RtlCopyUnicodeString (tp.u_get (&u_newpath), w_newpath);
+ return recursiveCopy (&u_oldpath, &u_newpath,
+ u_oldpath.Length, u_newpath.Length);
+ }
+ else
+ {
+ bool isdirlink = false;
+ if (win32_oldpath.issymlink () &&
+ win32_oldpath.is_known_reparse_point ())
+ {
+ /* Is there a better way to know this? */
+ DWORD attr = getfileattr (win32_oldpath.get_win32 (),
+ !!win32_oldpath.objcaseinsensitive ());
+ if (attr == INVALID_FILE_ATTRIBUTES)
+ {
+ __seterrno ();
+ return -1;
+ }
+ isdirlink = attr & FILE_ATTRIBUTE_DIRECTORY;
+ }
+ if (isdirlink)
+ {
+ /* CreateDirectoryEx seems to "copy" directory reparse points, which
+ CopyFileEx can only do with a flag introduced in 19041. */
+ if (!CreateDirectoryExW (w_oldpath->Buffer, w_newpath->Buffer, NULL))
+ {
+ debug_printf ("CreateDirectoryExW(%S, %S, 0) failed", w_oldpath,
+ w_newpath);
+ __seterrno ();
+ return -1;
+ }
+ }
+ else if (!CopyFileExW (w_oldpath->Buffer, w_newpath->Buffer, NULL, NULL,
+ NULL, COPY_FILE_COPY_SYMLINK))
+ {
+ __seterrno ();
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
int
symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice)
{
@@ -2112,6 +2357,13 @@ symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice)
case WSYM_nfs:
res = symlink_nfs (oldpath, win32_newpath);
__leave;
+ case WSYM_deepcopy:
+ res = symlink_deepcopy (oldpath, win32_newpath);
+ if (!res || res == -1)
+ __leave;
+ /* fall back to sysfile symlink type */
+ wsym_type = WSYM_sysfile;
+ break;
case WSYM_native:
case WSYM_nativestrict:
res = symlink_native (oldpath, win32_newpath);
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