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

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>

1 files changed, 15 insertions, 38 deletions

diff --git a/compat/mingw.c b/compat/mingw.c
index cf4f3c92e7..ae6826948e 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -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)