+static void reset_all_objects_flags()
+{
+ int i;
+
+ for (i = 0; i < obj_allocs; i++)
+ if (objs[i])
+ objs[i]->flags = 0;
+}
+
+static int get_patch_id(struct commit *commit, struct diff_options *options,
+ unsigned char *sha1)
+{
+ diff_tree_sha1(commit->parents->item->object.sha1, commit->object.sha1,
+ "", options);
+ diffcore_std(options);
+ return diff_flush_patch_id(options, sha1);
+}
+
+static void get_patch_ids(struct rev_info *rev, struct diff_options *options)
+{
+ struct rev_info check_rev;
+ struct commit *commit;
+ struct object *o1, *o2;
+ unsigned flags1, flags2;
+ unsigned char sha1[20];
+
+ if (rev->pending.nr != 2)
+ die("Need exactly one range.");
+
+ o1 = rev->pending.objects[0].item;
+ flags1 = o1->flags;
+ o2 = rev->pending.objects[1].item;
+ flags2 = o2->flags;
+
+ if ((flags1 & UNINTERESTING) == (flags2 & UNINTERESTING))
+ die("Not a range.");
+
+ diff_setup(options);
+ options->recursive = 1;
+ if (diff_setup_done(options) < 0)
+ die("diff_setup_done failed");
+
+ /* given a range a..b get all patch ids for b..a */
+ init_revisions(&check_rev);
+ o1->flags ^= UNINTERESTING;
+ o2->flags ^= UNINTERESTING;
+ add_pending_object(&check_rev, o1, "o1");
+ add_pending_object(&check_rev, o2, "o2");
+ prepare_revision_walk(&check_rev);
+
+ while ((commit = get_revision(&check_rev)) != NULL) {
+ /* ignore merges */
+ if (commit->parents && commit->parents->next)
+ continue;
+
+ if (!get_patch_id(commit, options, sha1))
+ created_object(sha1, xcalloc(1, sizeof(struct object)));
+ }
+
+ /* reset for next revision walk */
+ reset_all_objects_flags();
+ o1->flags = flags1;
+ o2->flags = flags2;
+}
+