move duplicated ref_newer() to remote.c

ref_newer() appears to have been copied from builtin-send-pack.c to
http-push.c via cut and paste. This patch moves the function and its
helper unmark_and_free() to remote.c. There was a slight difference
between the two implementations, one used TMP_MARK for the mark, the
other used 1. Per Jeff King, I went with TMP_MARK as more correct.

This is in preparation for being able to call it from builtin-remote.c

Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 49 insertions, 0 deletions

diff --git a/remote.c b/remote.c
index 01aae770a9..c8b7ea4ffa 100644
--- a/remote.c
+++ b/remote.c
@@ -5,6 +5,7 @@
 #include "diff.h"
 #include "revision.h"
 #include "dir.h"
+#include "tag.h"
 
 static struct refspec s_tag_refspec = {
 	0,
@@ -1269,6 +1270,54 @@ 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_list *temp = list;
+		temp->item->object.flags &= ~mark;
+		list = temp->next;
+		free(temp);
+	}
+}
+
+int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1)
+{
+	struct object *o;
+	struct commit *old, *new;
+	struct commit_list *list, *used;
+	int found = 0;
+
+	/* Both new and old must be commit-ish and new is descendant of
+	 * old.  Otherwise we require --force.
+	 */
+	o = deref_tag(parse_object(old_sha1), NULL, 0);
+	if (!o || o->type != OBJ_COMMIT)
+		return 0;
+	old = (struct commit *) o;
+
+	o = deref_tag(parse_object(new_sha1), NULL, 0);
+	if (!o || o->type != OBJ_COMMIT)
+		return 0;
+	new = (struct commit *) o;
+
+	if (parse_commit(new) < 0)
+		return 0;
+
+	used = list = NULL;
+	commit_list_insert(new, &list);
+	while (list) {
+		new = pop_most_recent_commit(&list, TMP_MARK);
+		commit_list_insert(new, &used);
+		if (new == old) {
+			found = 1;
+			break;
+		}
+	}
+	unmark_and_free(list, TMP_MARK);
+	unmark_and_free(used, TMP_MARK);
+	return found;
+}
+
 /*
  * Return true if there is anything to report, otherwise false.
  */