lock_ref_sha1_basic(): use raceproof_create_file()

Instead of coding the retry loop inline, use raceproof_create_file() to
make lock acquisition safe against directory creation/deletion races.

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

diff --git a/refs/files-backend.c b/refs/files-backend.c
index 7d4658aa94e7251f4d29cfea00c9454541f4c3e6..74de289f42b05b15f1aaf16246933c2e3ad847a0 100644 (file)
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1985,6 +1985,13 @@ static int remove_empty_directories(struct strbuf *path)
        return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
 }
 
+static int create_reflock(const char *path, void *cb)
+{
+       struct lock_file *lk = cb;
+
+       return hold_lock_file_for_update(lk, path, LOCK_NO_DEREF) < 0 ? -1 : 0;
+}
+
 /*
  * Locks a ref returning the lock on success and NULL on failure.
  * On failure errno is set to something meaningful.
@@ -2002,7 +2009,6 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
        int last_errno = 0;
        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
        int resolve_flags = RESOLVE_REF_NO_RECURSE;
-       int attempts_remaining = 3;
        int resolved;
 
        assert_main_repository(&refs->base, "lock_ref_sha1_basic");
@@ -2067,35 +2073,12 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
 
        lock->ref_name = xstrdup(refname);
 
- retry:
-       switch (safe_create_leading_directories_const(ref_file.buf)) {
-       case SCLD_OK:
-               break; /* success */
-       case SCLD_VANISHED:
-               if (--attempts_remaining > 0)
-                       goto retry;
-               /* fall through */
-       default:
+       if (raceproof_create_file(ref_file.buf, create_reflock, lock->lk)) {
                last_errno = errno;
-               strbuf_addf(err, "unable to create directory for '%s'",
-                           ref_file.buf);
+               unable_to_lock_message(ref_file.buf, errno, err);
                goto error_return;
        }
 
-       if (hold_lock_file_for_update(lock->lk, ref_file.buf, LOCK_NO_DEREF) < 0) {
-               last_errno = errno;
-               if (errno == ENOENT && --attempts_remaining > 0)
-                       /*
-                        * Maybe somebody just deleted one of the
-                        * directories leading to ref_file.  Try
-                        * again:
-                        */
-                       goto retry;
-               else {
-                       unable_to_lock_message(ref_file.buf, errno, err);
-                       goto error_return;
-               }
-       }
        if (verify_lock(lock, old_sha1, mustexist, err)) {
                last_errno = errno;
                goto error_return;