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mingw: don't call GetFileAttributes() twice in mingw_lstat()

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The Win32 API function `GetFileAttributes()` cannot handle paths with
trailing dir separators. The current `mingw_stat()`/`mingw_lstat()`
implementation calls `GetFileAttributes()` twice if the path has
trailing slashes (first with the original path that was passed as
function parameter, and and a second time with a path copy with trailing
'/' removed).

With the conversion to wide Unicode, we get the length of the path for
free, and also have a (wide char) buffer that can be modified. This
makes it easy to avoid that extraneous Win32 API call.

Signed-off-by: Karsten Blees <karsten.blees@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Karsten Blees 2026-01-09 20:04:58 +00:00 committed by Junio C Hamano
parent ec13dca8d0
commit 3b96b99683
1 changed files with 15 additions and 38 deletions
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53
compat/mingw.c
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@ -918,8 +918,9 @@ static int has_valid_directory_prefix(wchar_t *wfilename)
}
/* We keep the do_lstat code in a separate function to avoid recursion.
* When a path ends with a slash, the stat will fail with ENOENT. In
* this case, we strip the trailing slashes and stat again.
* When a path ends with a slash, the call to `GetFileAttributedExW()`
* would fail. To prevent this, we strip any trailing slashes before that
* call.
*
* If follow is true then act like stat() and report on the link
* target. Otherwise report on the link itself.
@ -928,9 +929,18 @@ static int do_lstat(int follow, const char *file_name, struct stat *buf)
{
WIN32_FILE_ATTRIBUTE_DATA fdata;
wchar_t wfilename[MAX_PATH];
if (xutftowcs_path(wfilename, file_name) < 0)
int wlen = xutftowcs_path(wfilename, file_name);
if (wlen < 0)
return -1;
/* strip trailing '/', or GetFileAttributes will fail */
while (wlen && is_dir_sep(wfilename[wlen - 1]))
wfilename[--wlen] = 0;
if (!wlen) {
errno = ENOENT;
return -1;
}
if (GetFileAttributesExW(wfilename, GetFileExInfoStandard, &fdata)) {
buf->st_ino = 0;
buf->st_gid = 0;
@ -990,39 +1000,6 @@ static int do_lstat(int follow, const char *file_name, struct stat *buf)
return -1;
}
/* We provide our own lstat/fstat functions, since the provided
* lstat/fstat functions are so slow. These stat functions are
* tailored for Git's usage (read: fast), and are not meant to be
* complete. Note that Git stat()s are redirected to mingw_lstat()
* too, since Windows doesn't really handle symlinks that well.
*/
static int do_stat_internal(int follow, const char *file_name, struct stat *buf)
{
size_t namelen;
char alt_name[PATH_MAX];
if (!do_lstat(follow, file_name, buf))
return 0;
/* if file_name ended in a '/', Windows returned ENOENT;
* try again without trailing slashes
*/
if (errno != ENOENT)
return -1;
namelen = strlen(file_name);
if (namelen && file_name[namelen-1] != '/')
return -1;
while (namelen && file_name[namelen-1] == '/')
--namelen;
if (!namelen || namelen >= PATH_MAX)
return -1;
memcpy(alt_name, file_name, namelen);
alt_name[namelen] = 0;
return do_lstat(follow, alt_name, buf);
}
static int get_file_info_by_handle(HANDLE hnd, struct stat *buf)
{
BY_HANDLE_FILE_INFORMATION fdata;
@ -1048,11 +1025,11 @@ static int get_file_info_by_handle(HANDLE hnd, struct stat *buf)
int mingw_lstat(const char *file_name, struct stat *buf)
{
return do_stat_internal(0, file_name, buf);
return do_lstat(0, file_name, buf);
}
int mingw_stat(const char *file_name, struct stat *buf)
{
return do_stat_internal(1, file_name, buf);
return do_lstat(1, file_name, buf);
}
int mingw_fstat(int fd, struct stat *buf)