+static struct ref *local_refs, **local_tail;
+static struct ref *remote_refs, **remote_tail;
+
+static int one_local_ref(const char *refname, const unsigned char *sha1)
+{
+ struct ref *ref;
+ int len = strlen(refname) + 1;
+ ref = xcalloc(1, sizeof(*ref) + len);
+ memcpy(ref->new_sha1, sha1, 20);
+ memcpy(ref->name, refname, len);
+ *local_tail = ref;
+ local_tail = &ref->next;
+ return 0;
+}
+
+static void one_remote_ref(char *refname)
+{
+ struct ref *ref;
+ unsigned char remote_sha1[20];
+ struct object *obj;
+
+ if (fetch_ref(refname, remote_sha1) != 0) {
+ fprintf(stderr,
+ "Unable to fetch ref %s from %s\n",
+ refname, remote->url);
+ return;
+ }
+
+ /*
+ * Fetch a copy of the object if it doesn't exist locally - it
+ * may be required for updating server info later.
+ */
+ if (remote->can_update_info_refs && !has_sha1_file(remote_sha1)) {
+ obj = lookup_unknown_object(remote_sha1);
+ if (obj) {
+ fprintf(stderr, " fetch %s for %s\n",
+ sha1_to_hex(remote_sha1), refname);
+ add_fetch_request(obj);
+ }
+ }
+
+ int len = strlen(refname) + 1;
+ ref = xcalloc(1, sizeof(*ref) + len);
+ memcpy(ref->old_sha1, remote_sha1, 20);
+ memcpy(ref->name, refname, len);
+ *remote_tail = ref;
+ remote_tail = &ref->next;
+}
+
+static void get_local_heads(void)
+{
+ local_tail = &local_refs;
+ for_each_ref(one_local_ref);
+}
+
+static void get_dav_remote_heads(void)
+{
+ remote_tail = &remote_refs;
+ remote_ls("refs/", (PROCESS_FILES | PROCESS_DIRS | RECURSIVE), process_ls_ref, NULL);
+}
+
+static int is_zero_sha1(const unsigned char *sha1)
+{
+ int i;
+
+ for (i = 0; i < 20; i++) {
+ if (*sha1++)
+ return 0;
+ }
+ 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);
+ }
+}
+
+static 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 != commit_type)
+ return 0;
+ old = (struct commit *) o;
+
+ o = deref_tag(parse_object(new_sha1), NULL, 0);
+ if (!o || o->type != commit_type)
+ 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;
+}
+
+static void mark_edge_parents_uninteresting(struct commit *commit)
+{
+ struct commit_list *parents;
+
+ for (parents = commit->parents; parents; parents = parents->next) {
+ struct commit *parent = parents->item;
+ if (!(parent->object.flags & UNINTERESTING))
+ continue;
+ mark_tree_uninteresting(parent->tree);
+ }
+}
+
+static void mark_edges_uninteresting(struct commit_list *list)
+{
+ for ( ; list; list = list->next) {
+ struct commit *commit = list->item;
+
+ if (commit->object.flags & UNINTERESTING) {
+ mark_tree_uninteresting(commit->tree);
+ continue;
+ }
+ mark_edge_parents_uninteresting(commit);
+ }
+}
+
+static void add_remote_info_ref(struct remote_ls_ctx *ls)