X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=update-ref.c;h=65dc3d6385756a11aac257a3ed6a9dfcb68cce53;hb=e24317b4d093e4b148996172d0b749f09a0e6f2e;hp=127ef99eeda03de4ef84a2cfbe473df8f896e3f4;hpb=66bf85a462893f9df7e516a5f334dbba08122617;p=git.git

diff --git a/update-ref.c b/update-ref.c
index 127ef99e..65dc3d63 100644
--- a/update-ref.c
+++ b/update-ref.c
@@ -3,51 +3,17 @@
 
 static const char git_update_ref_usage[] = "git-update-ref <refname> <value> [<oldval>]";
 
-#define MAXDEPTH 5
-
-const char *resolve_ref(const char *path, unsigned char *sha1)
+static int re_verify(const char *path, unsigned char *oldsha1, unsigned char *currsha1)
 {
-	int depth = MAXDEPTH, len;
-	char buffer[256];
-
-	for (;;) {
-		struct stat st;
-		int fd;
-
-		if (--depth < 0)
-			return NULL;
-
-		/* Special case: non-existing file */
-		if (lstat(path, &st) < 0) {
-			if (errno != ENOENT)
-				return NULL;
-			memset(sha1, 0, 20);
-			return path;
-		}
-
-		/* Follow "normalized" - ie "refs/.." symlinks by hand */
-		if (S_ISLNK(st.st_mode)) {
-			len = readlink(path, buffer, sizeof(buffer)-1);
-			if (len >= 5 && !memcmp("refs/", buffer, 5)) {
-				path = git_path("%.*s", len, buffer);
-				continue;
-			}
-		}
-
-		/*
-		 * Anything else, just open it and try to use it as
-		 * a ref
-		 */
-		fd = open(path, O_RDONLY);
-		if (fd < 0)
-			return NULL;
-		len = read(fd, buffer, sizeof(buffer)-1);
-		close(fd);
-		break;
-	}
-	if (len < 40 || get_sha1_hex(buffer, sha1))
-		return NULL;
-	return path;
+	char buf[40];
+	int fd = open(path, O_RDONLY), nr;
+	if (fd < 0)
+		return -1;
+	nr = read(fd, buf, 40);
+	close(fd);
+	if (nr != 40 || get_sha1_hex(buf, currsha1) < 0)
+		return -1;
+	return memcmp(oldsha1, currsha1, 20) ? -1 : 0;
 }
 
 int main(int argc, char **argv)
@@ -70,7 +36,7 @@ int main(int argc, char **argv)
 	if (oldval && get_sha1(oldval, oldsha1) < 0)
 		die("%s: not a valid old SHA1", oldval);
 
-	path = resolve_ref(git_path("%s", refname), currsha1);
+	path = resolve_ref(git_path("%s", refname), currsha1, !!oldval);
 	if (!path)
 		die("No such ref: %s", refname);
 
@@ -97,12 +63,16 @@ int main(int argc, char **argv)
 	}
 
 	/*
-	 * FIXME!
-	 *
-	 * We should re-read the old ref here, and re-verify that it
-	 * matches "oldsha1". Otherwise there's a small race.
+	 * Re-read the ref after getting the lock to verify
 	 */
+	if (oldval && re_verify(path, oldsha1, currsha1) < 0) {
+		unlink(lockpath);
+		die("Ref lock failed");
+	}
 
+	/*
+	 * Finally, replace the old ref with the new one
+	 */
 	if (rename(lockpath, path) < 0) {
 		unlink(lockpath);
 		die("Unable to create %s", path);