Function for updating refs.

A function intended to be called from builtins updating refs
by locking them before write, specially those that came from
scripts using "git update-ref".

[jc: with minor fixups]

Signed-off-by: Carlos Rica <jasampler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/refs.c b/refs.c
index 09a2c87fc..7fb335078 100644
--- a/refs.c
+++ b/refs.c
@@ -1455,3 +1455,30 @@ int for_each_reflog(each_ref_fn fn, void *cb_data)
 {
 	return do_for_each_reflog("", fn, cb_data);
 }
+
+int update_ref(const char *action, const char *refname,
+		const unsigned char *sha1, const unsigned char *oldval,
+		int flags, enum action_on_err onerr)
+{
+	static struct ref_lock *lock;
+	lock = lock_any_ref_for_update(refname, oldval, flags);
+	if (!lock) {
+		const char *str = "Cannot lock the ref '%s'.";
+		switch (onerr) {
+		case MSG_ON_ERR: error(str, refname); break;
+		case DIE_ON_ERR: die(str, refname); break;
+		case QUIET_ON_ERR: break;
+		}
+		return 1;
+	}
+	if (write_ref_sha1(lock, sha1, action) < 0) {
+		const char *str = "Cannot update the ref '%s'.";
+		switch (onerr) {
+		case MSG_ON_ERR: error(str, refname); break;
+		case DIE_ON_ERR: die(str, refname); break;
+		case QUIET_ON_ERR: break;
+		}
+		return 1;
+	}
+	return 0;
+}