safe_create_leading_directories(): add explicit "slash" pointer

Keep track of the position of the slash character independently of
"pos", thereby making the purpose of each variable clearer and
working towards other upcoming changes.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sha1_file.c

@@ -111,19 +111,21 @@ int safe_create_leading_directories(char *path)
 
 	while (pos) {
 		struct stat st;
+		char *slash = strchr(pos, '/');
 
-		pos = strchr(pos, '/');
+		if (!slash)
-		if (!pos)
 			break;
-		while (*++pos == '/')
+		while (*(slash + 1) == '/')
-			;
+			slash++;
+		pos = slash + 1;
 		if (!*pos)
 			break;
-		*--pos = '\0';
+
+		*slash = '\0';
 		if (!stat(path, &st)) {
 			/* path exists */
 			if (!S_ISDIR(st.st_mode)) {
-				*pos = '/';
+				*slash = '/';
 				return -3;
 			}
 		} else if (mkdir(path, 0777)) {
@@ -131,14 +133,14 @@ int safe_create_leading_directories(char *path)
 			    !stat(path, &st) && S_ISDIR(st.st_mode)) {
 				; /* somebody created it since we checked */
 			} else {
-				*pos = '/';
+				*slash = '/';
 				return -1;
 			}
 		} else if (adjust_shared_perm(path)) {
-			*pos = '/';
+			*slash = '/';
 			return -2;
 		}
-		*pos++ = '/';
+		*slash = '/';
 	}
 	return 0;
 }