commit_ref_update(): new function, extracted from write_ref_sha1()

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

refs.c

@@ -3085,24 +3085,13 @@ static int write_ref_to_lockfile(struct ref_lock *lock,
 }
 
 /*
- * Write sha1 into the ref specified by the lock. Make sure that errno
- * is sane on error.
+ * Commit a change to a loose reference that has already been written
+ * to the loose reference lockfile. Also update the reflogs if
+ * necessary, using the specified lockmsg (which can be NULL).
  */
-static int write_ref_sha1(struct ref_lock *lock,
-	const unsigned char *sha1, const char *logmsg)
+static int commit_ref_update(struct ref_lock *lock,
+			     const unsigned char *sha1, const char *logmsg)
 {
-	if (!lock) {
-		errno = EINVAL;
-		return -1;
-	}
-	if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
-		unlock_ref(lock);
-		return 0;
-	}
-
-	if (write_ref_to_lockfile(lock, sha1))
-		return -1;
-
 	clear_loose_ref_cache(&ref_cache);
 	if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
 	    (strcmp(lock->ref_name, lock->orig_ref_name) &&
@@ -3141,6 +3130,30 @@ static int write_ref_sha1(struct ref_lock *lock,
 	return 0;
 }
 
+/*
+ * Write sha1 as the new value of the reference specified by the
+ * (open) lock. On error, roll back the lockfile and set errno
+ * appropriately.
+ */
+static int write_ref_sha1(struct ref_lock *lock,
+			  const unsigned char *sha1, const char *logmsg)
+{
+	if (!lock) {
+		errno = EINVAL;
+		return -1;
+	}
+	if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
+		unlock_ref(lock);
+		return 0;
+	}
+
+	if (write_ref_to_lockfile(lock, sha1) ||
+	    commit_ref_update(lock, sha1, logmsg))
+		return -1;
+
+	return 0;
+}
+
 int create_symref(const char *ref_target, const char *refs_heads_master,
 		  const char *logmsg)
 {