path.c: optimize adjust_shared_perm()

Sometimes the chown() function is called even when not needed (This
can be provoked by running t1301, and adding some debug code).

Save a chmod from 400 to 400, or from 600 to 600 on these files:

.git/info/refs+
.git/objects/info/packs+

Save chmod on directories from 2770 to 2770:

.git/refs
.git/refs/heads
.git/refs/tags

Signed-off-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/path.c b/path.c
index e27959a12bc5031d8d660a2fb9bfe591e43e4d65..04ff1487ed31685b6b3f7923f9bfbfc7217f70a0 100644 (file)
--- a/path.c
+++ b/path.c
@@ -396,22 +396,14 @@ const char *enter_repo(const char *path, int strict)
        return NULL;
 }
 
-int adjust_shared_perm(const char *path)
+static int calc_shared_perm(int mode)
 {
-       int tweak, shared, orig_mode, mode;
+       int tweak;
 
-       if (!shared_repository) {
-               return 0;
-       }
-       if (get_st_mode_bits(path, &mode) < 0)
-               return -1;
-
-       orig_mode = mode;
        if (shared_repository < 0)
-               shared = -shared_repository;
+               tweak = -shared_repository;
        else
-               shared = shared_repository;
-       tweak = shared;
+               tweak = shared_repository;
 
        if (!(mode & S_IWUSR))
                tweak &= ~0222;
@@ -423,16 +415,28 @@ int adjust_shared_perm(const char *path)
        else
                mode |= tweak;
 
-       if (S_ISDIR(mode)) {
+       return mode;
+}
+
+
+int adjust_shared_perm(const char *path)
+{
+       int old_mode, new_mode;
+
+       if (!shared_repository)
+               return 0;
+       if (get_st_mode_bits(path, &old_mode) < 0)
+               return -1;
+
+       new_mode = calc_shared_perm(old_mode);
+       if (S_ISDIR(old_mode)) {
                /* Copy read bits to execute bits */
-               mode |= (shared & 0444) >> 2;
-               mode |= FORCE_DIR_SET_GID;
+               new_mode |= (new_mode & 0444) >> 2;
+               new_mode |= FORCE_DIR_SET_GID;
        }
 
-       if (((shared_repository < 0
-             ? (orig_mode & (FORCE_DIR_SET_GID | 0777))
-             : (orig_mode & mode)) != mode) &&
-           chmod(path, (mode & ~S_IFMT)) < 0)
+       if (((old_mode ^ new_mode) & ~S_IFMT) &&
+                       chmod(path, (new_mode & ~S_IFMT)) < 0)
                return -2;
        return 0;
 }