commit-reach: move ref_newer from remote.c

There are several commit walks in the codebase. Group them together into
a new commit-reach.c file and corresponding header. After we group these
walks into one place, we can reduce duplicate logic by calling
equivalent methods.

The ref_newer() method is used by 'git push -f' to check if a force-push
is necessary. By making the method public, we make it possible to test
the method directly without setting up an envieronment where a 'git
push' call makes sense.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 0 insertions, 49 deletions

diff --git a/remote.c b/remote.c
index 8e99b9888a..f0c23bae48 100644
--- a/remote.c
+++ b/remote.c
@@ -1784,55 +1784,6 @@ int resolve_remote_symref(struct ref *ref, struct ref *list)
 	return 1;
 }
 
-static void unmark_and_free(struct commit_list *list, unsigned int mark)
-{
-	while (list) {
-		struct commit *commit = pop_commit(&list);
-		commit->object.flags &= ~mark;
-	}
-}
-
-int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid)
-{
-	struct object *o;
-	struct commit *old_commit, *new_commit;
-	struct commit_list *list, *used;
-	int found = 0;
-
-	/*
-	 * Both new_commit and old_commit must be commit-ish and new_commit is descendant of
-	 * old_commit.  Otherwise we require --force.
-	 */
-	o = deref_tag(the_repository, parse_object(the_repository, old_oid),
-		      NULL, 0);
-	if (!o || o->type != OBJ_COMMIT)
-		return 0;
-	old_commit = (struct commit *) o;
-
-	o = deref_tag(the_repository, parse_object(the_repository, new_oid),
-		      NULL, 0);
-	if (!o || o->type != OBJ_COMMIT)
-		return 0;
-	new_commit = (struct commit *) o;
-
-	if (parse_commit(new_commit) < 0)
-		return 0;
-
-	used = list = NULL;
-	commit_list_insert(new_commit, &list);
-	while (list) {
-		new_commit = pop_most_recent_commit(&list, TMP_MARK);
-		commit_list_insert(new_commit, &used);
-		if (new_commit == old_commit) {
-			found = 1;
-			break;
-		}
-	}
-	unmark_and_free(list, TMP_MARK);
-	unmark_and_free(used, TMP_MARK);
-	return found;
-}
-
 /*
  * Lookup the upstream branch for the given branch and if present, optionally
  * compute the commit ahead/behind values for the pair.