[PATCH] refs.c: handle locking failure during transaction better

[Stefan Beller <sbeller@google.com>]

From: Ronnie Sahlberg <sahlberg@google.com>

Change lock_ref_sha1_basic to return an error instead of dying,
when we fail to lock a file during a transaction. This function is
only called from transaction_commit() and it knows how to handle
these failures.

[sb: This was part of a larger patch series, cherry-picked to master]

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
---
 refs.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/refs.c b/refs.c
index 5ff457e..0347328 100644
--- a/refs.c
+++ b/refs.c
@@ -2318,6 +2318,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 
 	lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
 	if (lock->lock_fd < 0) {
+		last_errno = errno;
 		if (errno == ENOENT && --attempts_remaining > 0)
 			/*
 			 * Maybe somebody just deleted one of the
@@ -2325,8 +2326,13 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 			 * again:
 			 */
 			goto retry;
-		else
-			unable_to_lock_die(ref_file, errno);
+		else {
+			struct strbuf err = STRBUF_INIT;
+			unable_to_lock_message(ref_file, errno, &err);
+			error("%s", err.buf);
+			strbuf_reset(&err);
+			goto error_return;
+		}
 	}
 	return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 
-- 
2.2.0.rc2.5.gf7b9fb2