-/* This function should make sure errno is meaningful on error */
-static struct ref_lock *verify_lock(struct ref_lock *lock,
- const unsigned char *old_sha1, int mustexist)
+/*
+ * Verify that the reference locked by lock has the value old_sha1.
+ * Fail if the reference doesn't exist and mustexist is set. Return 0
+ * on success or a negative value on error. This function should make
+ * sure errno is meaningful on error.
+ */
+static int verify_lock(struct ref_lock *lock,
+ const unsigned char *old_sha1, int mustexist)