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Support symbolic links on Windows #2018

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Support symbolic links on Windows #2018

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9693157
t9700: accommodate for Windows paths
dscho Dec 16, 2025
33ccd0f
apply: symbolic links lack a "trustable executable bit"
dscho Dec 16, 2025
78d52c8
mingw: special-case `open(symlink, O_CREAT | O_EXCL)`
dscho Dec 16, 2025
c8fb79c
t0001: handle `diff --no-index` gracefully
dscho Dec 16, 2025
d2de5d9
t0301: another fix for Windows compatibility
dscho Dec 16, 2025
14b033f
t0600: fix incomplete prerequisite for a test case
dscho Dec 5, 2025
c670ae3
t1006: accommodate for symlink support in MSYS2
dscho Dec 16, 2025
d265cde
t1305: skip symlink tests that do not apply to Windows
dscho Dec 16, 2025
02ea262
t6423: introduce Windows-specific handling for symlinking to /dev/null
dscho Dec 16, 2025
a4c7170
t7800: work around the MSYS path conversion on Windows
dscho Dec 16, 2025
359de97
Merge branch 'js/test-symlink-windows' into js/prep-symlink-windows
gitster Dec 16, 2025
df27101
mingw: do resolve symlinks in `getcwd()`
dscho Dec 16, 2025
722e65d
init: do parse _all_ core.* settings early
dscho Dec 16, 2025
f6b8e4a
strbuf_readlink(): avoid calling `readlink()` twice in corner-cases
kblees Dec 16, 2025
9ce11d9
strbuf_readlink(): support link targets that exceed PATH_MAX
kblees Dec 16, 2025
6f6fe02
trim_last_path_component(): avoid hard-coding the directory separator
kblees Dec 16, 2025
dae450d
mingw: don't call `GetFileAttributes()` twice in `mingw_lstat()`
kblees May 12, 2015
c36848e
mingw: implement `stat()` with symlink support
kblees May 15, 2015
aa0ca80
mingw: drop the separate `do_lstat()` function
kblees May 11, 2015
8860443
mingw: let `mingw_lstat()` error early upon problems with reparse points
kblees May 23, 2015
db1d156
mingw: teach dirent about symlinks
kblees Jan 10, 2017
4c49a3d
mingw: compute the correct size for symlinks in `mingw_lstat()`
billziss-gh May 28, 2020
ad74d54
mingw: factor out the retry logic
kblees May 19, 2015
25313ce
mingw: change default of `core.symlinks` to false
kblees May 23, 2015
b698f4a
mingw: add symlink-specific error codes
kblees May 15, 2015
282aba4
mingw: handle symlinks to directories in `mingw_unlink()`
kblees May 23, 2015
5cb3b10
mingw: support renaming symlinks
kblees May 19, 2015
4992083
mingw: allow `mingw_chdir()` to change to symlink-resolved directories
kblees May 23, 2015
8fef822
mingw: implement `readlink()`
kblees May 23, 2015
1dd5f9d
mingw: implement basic `symlink()` functionality (file symlinks only)
kblees May 23, 2015
7b6dbc7
mingw: add support for symlinks to directories
kblees May 23, 2015
d3b89c2
mingw: try to create symlinks without elevated permissions
dscho May 30, 2017
2e73ab4
mingw: emulate `stat()` a little more faithfully
dscho Mar 2, 2020
817f488
mingw: special-case index entries for symlinks with buggy size
dscho Jun 4, 2020
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2 changes: 1 addition & 1 deletion apply.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3818,7 +3818,7 @@ static int check_preimage(struct apply_state *state,
if (*ce && !(*ce)->ce_mode)
BUG("ce_mode == 0 for path '%s'", old_name);

if (trust_executable_bit)
if (trust_executable_bit || !S_ISREG(st->st_mode))
st_mode = ce_mode_from_stat(*ce, st->st_mode);
else if (*ce)
st_mode = (*ce)->ce_mode;
Expand Down
6 changes: 2 additions & 4 deletions compat/mingw-posix.h
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Original file line number Diff line number Diff line change
Expand Up @@ -121,10 +121,6 @@ struct utsname {
* trivial stubs
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@gitgitgadget gitgitgadget bot Dec 18, 2025

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On the Git mailing list, Johannes Sixt wrote (reply to this):

Am 17.12.25 um 15:08 schrieb Karsten Blees via GitGitGadget:
> From: Karsten Blees <blees@dcon.de>
> 
> Implement `readlink()` by reading NTFS reparse points via the
> `read_reparse_point()` function that was introduced earlier to determine
> the length of symlink targets. Works for symlinks and directory
> junctions. If symlinks are disabled, fail with `ENOSYS`.

This last sentence is obsolete, I think, because I cannot see how the
patch achieves a failure with ENOSYS.

> 
> Signed-off-by: Karsten Blees <blees@dcon.de>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
>  compat/mingw-posix.h |  3 +--
>  compat/mingw.c       | 24 ++++++++++++++++++++++++
>  2 files changed, 25 insertions(+), 2 deletions(-)
> 
> diff --git a/compat/mingw-posix.h b/compat/mingw-posix.h
> index 0939feff27..896aa976b1 100644
> --- a/compat/mingw-posix.h
> +++ b/compat/mingw-posix.h
> @@ -121,8 +121,6 @@ struct utsname {
>   * trivial stubs
>   */
>  
> -static inline int readlink(const char *path UNUSED, char *buf UNUSED, size_t bufsiz UNUSED)
> -{ errno = ENOSYS; return -1; }
>  static inline int symlink(const char *oldpath UNUSED, const char *newpath UNUSED)
>  { errno = ENOSYS; return -1; }
>  static inline int fchmod(int fildes UNUSED, mode_t mode UNUSED)
> @@ -197,6 +195,7 @@ int setitimer(int type, struct itimerval *in, struct itimerval *out);
>  int sigaction(int sig, struct sigaction *in, struct sigaction *out);
>  int link(const char *oldpath, const char *newpath);
>  int uname(struct utsname *buf);
> +int readlink(const char *path, char *buf, size_t bufsiz);
>  
>  /*
>   * replacements of existing functions
> diff --git a/compat/mingw.c b/compat/mingw.c
> index 5d2a8c247c..b407a2ac07 100644
> --- a/compat/mingw.c
> +++ b/compat/mingw.c
> @@ -2698,6 +2698,30 @@ int link(const char *oldpath, const char *newpath)
>  	return 0;
>  }
>  
> +int readlink(const char *path, char *buf, size_t bufsiz)
> +{
> +	WCHAR wpath[MAX_PATH];
> +	char tmpbuf[MAX_PATH];
> +	int len;
> +	DWORD tag;
> +
> +	if (xutftowcs_path(wpath, path) < 0)
> +		return -1;
> +
> +	if (read_reparse_point(wpath, TRUE, tmpbuf, &len, &tag) < 0)
> +		return -1;
> +
> +	/*
> +	 * Adapt to strange readlink() API: Copy up to bufsiz *bytes*, potentially
> +	 * cutting off a UTF-8 sequence. Insufficient bufsize is *not* a failure
> +	 * condition. There is no conversion function that produces invalid UTF-8,
> +	 * so convert to a (hopefully large enough) temporary buffer, then memcpy
> +	 * the requested number of bytes (including '\0' for robustness).
> +	 */
> +	memcpy(buf, tmpbuf, min(bufsiz, len + 1));
> +	return min(bufsiz, len);
> +}
> +
>  pid_t waitpid(pid_t pid, int *status, int options)
>  {
>  	HANDLE h = OpenProcess(SYNCHRONIZE | PROCESS_QUERY_INFORMATION,

-- Hannes

*/

static inline int readlink(const char *path UNUSED, char *buf UNUSED, size_t bufsiz UNUSED)
{ errno = ENOSYS; return -1; }
static inline int symlink(const char *oldpath UNUSED, const char *newpath UNUSED)
{ errno = ENOSYS; return -1; }
static inline int fchmod(int fildes UNUSED, mode_t mode UNUSED)
{ errno = ENOSYS; return -1; }
#ifndef __MINGW64_VERSION_MAJOR
Expand Down Expand Up @@ -197,6 +193,8 @@ int setitimer(int type, struct itimerval *in, struct itimerval *out);
int sigaction(int sig, struct sigaction *in, struct sigaction *out);
int link(const char *oldpath, const char *newpath);
int uname(struct utsname *buf);
int symlink(const char *target, const char *link);
int readlink(const char *path, char *buf, size_t bufsiz);

/*
* replacements of existing functions
Expand Down
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