[PATCH] Add a new lstat implementation based on Win32 API, and make stat use that implementation too.

[Marius Storm-Olsen <marius@trolltech.com>]

This gives us a significant speedup when adding, committing and stat'ing files.
(Also, since Windows doesn't really handle symlinks, it's fine that stat just uses lstat)

Signed-off-by: Marius Storm-Olsen <mstormo_git@storm-olsen.com>
---
 Revision #2 of the patch.
 For this one I change the filetime_to_time_t function to do the
 timestamp conversion inline in the FILETIME struct. That way we
 also avoid one assignment, bitshifting and addition.
 Sneaky, huh? ;-)
 New stats:
    -------------------------
    Command: git init
    -------------------------

    real    0m0.047s
    user    0m0.031s
    sys     0m0.000s

    -------------------------
    Command: git add .
    -------------------------

    real    0m12.016s
    user    0m0.015s
    sys     0m0.000s

    -------------------------
    Command: git commit -a...
    -------------------------

    real    0m17.031s
    user    0m0.015s
    sys     0m0.030s

    -------------------------
    3x Command: git-status
    -------------------------

    real    0m5.265s
    user    0m0.015s
    sys     0m0.015s

    real    0m5.297s
    user    0m0.015s
    sys     0m0.000s

    real    0m5.250s
    user    0m0.015s
    sys     0m0.016s

    -------------------------
    Command: git commit...
    (single file)
    -------------------------

    real    0m7.859s
    user    0m0.015s
    sys     0m0.015s


 compat/mingw.c    |   41 +++++++++++++++++++++++++++++++++--------
 git-compat-util.h |    4 ++++
 2 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index 7711a3f..86a1419 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -23,19 +23,44 @@ int fchmod(int fildes, mode_t mode)
 	return -1;
 }

-int lstat(const char *file_name, struct stat *buf)
+static inline time_t filetime_to_time_t(const FILETIME *ft)
+{
+	long long *winTime = (long long*)ft;
+	*winTime -= 116444736000000000LL; /* Windows to Unix Epoch conversion */
+	*winTime /= 10000000;		  /* Nano to seconds resolution */
+	return (time_t)ft->dwLowDateTime;
+}
+
+extern int _getdrive( void );
+int git_lstat(const char *file_name, struct stat *buf)
 {
 	int namelen;
 	static char alt_name[PATH_MAX];
-
-	if (!stat(file_name, buf))
+	WIN32_FILE_ATTRIBUTE_DATA fdata;
+
+	if (GetFileAttributesExA(file_name, GetFileExInfoStandard, &fdata)) {
+		int fMode = S_IREAD;
+		if (fdata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
+			fMode |= S_IFDIR;
+		else
+			fMode |= S_IFREG;
+		if (!(fdata.dwFileAttributes & FILE_ATTRIBUTE_READONLY))
+			fMode |= S_IWRITE;
+
+		buf->st_ino = 0;
+		buf->st_gid = 0;
+		buf->st_uid = 0;
+		buf->st_nlink = 1;
+		buf->st_mode = fMode;
+		buf->st_size = fdata.nFileSizeLow; /* Can't use nFileSizeHigh, since it's not a stat64 */
+		buf->st_dev = buf->st_rdev = (_getdrive() - 1);
+		buf->st_atime = filetime_to_time_t(&(fdata.ftLastAccessTime));
+		buf->st_mtime = filetime_to_time_t(&(fdata.ftLastWriteTime));
+		buf->st_ctime = filetime_to_time_t(&(fdata.ftCreationTime));
 		return 0;
+	}
+	errno = ENOENT;

-	/* 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;
diff --git a/git-compat-util.h b/git-compat-util.h
index 1ba499f..4122465 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -488,6 +488,10 @@ int mingw_rename(const char*, const char*);
 extern void quote_argv(const char **dst, const char **src);
 extern const char *parse_interpreter(const char *cmd);

+/* Make git on Windows use git_lstat instead of lstat and stat */
+int git_lstat(const char *file_name, struct stat *buf);
+#define lstat(x,y) git_lstat(x,y)
+#define stat(x,y) git_lstat(x,y)
 #endif /* __MINGW32__ */

 #endif
--
1.5.3.GIT-dirty