lockfile: do not rollback lock on failed close

Since the lockfile code is based on the tempfile code, it
has some of the same problems, including that close_lock_file()
erases the tempfile's filename buf, making it hard for the
caller to write a good error message.

In practice this comes up less for lockfiles than for
straight tempfiles, since we usually just report the
refname. But there is at least one buggy case in
write_ref_to_lockfile(). Besides, given the coupling between
the lockfile and tempfile modules, it's less confusing if
their close() functions have the same semantics.

Just as the previous commit did for close_tempfile(), let's
teach close_lock_file() and its wrapper close_ref() not to
rollback on error. And just as before, we'll give them new
"gently" names to catch any new callers that are added.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/refs/files-backend.c b/refs/files-backend.c
index fccbc24ac..bc1899cd4 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1402,9 +1402,9 @@ static int files_rename_ref(struct ref_store *ref_store,
 	return ret;
 }
 
-static int close_ref(struct ref_lock *lock)
+static int close_ref_gently(struct ref_lock *lock)
 {
-	if (close_lock_file(lock->lk))
+	if (close_lock_file_gently(lock->lk))
 		return -1;
 	return 0;
 }
@@ -1630,7 +1630,7 @@ static int write_ref_to_lockfile(struct ref_lock *lock,
 	fd = get_lock_file_fd(lock->lk);
 	if (write_in_full(fd, oid_to_hex(oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ ||
 	    write_in_full(fd, &term, 1) != 1 ||
-	    close_ref(lock) < 0) {
+	    close_ref_gently(lock) < 0) {
 		strbuf_addf(err,
 			    "couldn't write '%s'", get_lock_file_path(lock->lk));
 		unlock_ref(lock);
@@ -2372,7 +2372,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 		 * the lockfile is still open. Close it to
 		 * free up the file descriptor:
 		 */
-		if (close_ref(lock)) {
+		if (close_ref_gently(lock)) {
 			strbuf_addf(err, "couldn't close '%s.lock'",
 				    update->refname);
 			return TRANSACTION_GENERIC_ERROR;
@@ -2848,14 +2848,15 @@ static int files_reflog_expire(struct ref_store *ref_store,
 			!(type & REF_ISSYMREF) &&
 			!is_null_oid(&cb.last_kept_oid);
 
-		if (close_lock_file(&reflog_lock)) {
+		if (close_lock_file_gently(&reflog_lock)) {
 			status |= error("couldn't write %s: %s", log_file,
 					strerror(errno));
+			rollback_lock_file(&reflog_lock);
 		} else if (update &&
 			   (write_in_full(get_lock_file_fd(lock->lk),
 				oid_to_hex(&cb.last_kept_oid), GIT_SHA1_HEXSZ) != GIT_SHA1_HEXSZ ||
 			    write_str_in_full(get_lock_file_fd(lock->lk), "\n") != 1 ||
-			    close_ref(lock) < 0)) {
+			    close_ref_gently(lock) < 0)) {
 			status |= error("couldn't write %s",
 					get_lock_file_path(lock->lk));
 			rollback_lock_file(&reflog_lock);