refactor ref status logic for pushing

Move the logic that detects up-to-date and non-fast-forward refs to a
new function in remote.[ch], set_ref_status_for_push().

Make transport_push() invoke set_ref_status_for_push() before invoking
the push_refs() implementation. (As a side-effect, the push_refs()
implementation in transport-helper.c now knows of non-fast-forward
pushes.)

Removed logic for detecting up-to-date refs from the push_refs()
implementation in transport-helper.c, as transport_push() has already
done so for it.

Make cmd_send_pack() invoke set_ref_status_for_push() before invoking
send_pack(), as transport_push() can't do it for send_pack() here.

Mark the test on the return status of non-fast-forward push to fail.
Git now exits with success, as transport.c::transport_push() does not
check for refs with status REF_STATUS_REJECT_NONFASTFORWARD nor does it
indicate rejected pushes with its return value.

Mark the test for ref status to succeed. As mentioned earlier, refs
might be marked as non-fast-forwards, triggering the push status
printing mechanism in transport.c.

Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 50 insertions, 0 deletions

diff --git a/remote.c b/remote.c
index e3afecdb1..c70181cdc 100644
--- a/remote.c
+++ b/remote.c
@@ -1247,6 +1247,56 @@ int match_refs(struct ref *src, struct ref **dst,
 	return 0;
 }
 
+void set_ref_status_for_push(struct ref *remote_refs, int send_mirror,
+	int force_update)
+{
+	struct ref *ref;
+
+	for (ref = remote_refs; ref; ref = ref->next) {
+		if (ref->peer_ref)
+			hashcpy(ref->new_sha1, ref->peer_ref->new_sha1);
+		else if (!send_mirror)
+			continue;
+
+		ref->deletion = is_null_sha1(ref->new_sha1);
+		if (!ref->deletion &&
+			!hashcmp(ref->old_sha1, ref->new_sha1)) {
+			ref->status = REF_STATUS_UPTODATE;
+			continue;
+		}
+
+		/* This part determines what can overwrite what.
+		 * The rules are:
+		 *
+		 * (0) you can always use --force or +A:B notation to
+		 *     selectively force individual ref pairs.
+		 *
+		 * (1) if the old thing does not exist, it is OK.
+		 *
+		 * (2) if you do not have the old thing, you are not allowed
+		 *     to overwrite it; you would not know what you are losing
+		 *     otherwise.
+		 *
+		 * (3) if both new and old are commit-ish, and new is a
+		 *     descendant of old, it is OK.
+		 *
+		 * (4) regardless of all of the above, removing :B is
+		 *     always allowed.
+		 */
+
+		ref->nonfastforward =
+			!ref->deletion &&
+			!is_null_sha1(ref->old_sha1) &&
+			(!has_sha1_file(ref->old_sha1)
+			  || !ref_newer(ref->new_sha1, ref->old_sha1));
+
+		if (ref->nonfastforward && !ref->force && !force_update) {
+			ref->status = REF_STATUS_REJECT_NONFASTFORWARD;
+			continue;
+		}
+	}
+}
+
 struct branch *branch_get(const char *name)
 {
 	struct branch *ret;