1 /*
2  * Copyright (c) 2018, 2019, 2020 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/types.h>
18 #include <sys/stat.h>
19 #include <sys/queue.h>
20 #include <sys/stdint.h>
21 
22 #include <limits.h>
23 #include <stdio.h>
24 #include <stdlib.h>
25 #include <string.h>
26 #include <sha1.h>
27 #include <sha2.h>
28 #include <zlib.h>
29 #include <ctype.h>
30 
31 #include "got_error.h"
32 #include "got_object.h"
33 #include "got_cancel.h"
34 #include "got_commit_graph.h"
35 #include "got_path.h"
36 
37 #include "got_lib_delta.h"
38 #include "got_lib_inflate.h"
39 #include "got_lib_object.h"
40 #include "got_lib_object_idset.h"
41 
42 struct got_commit_graph_node {
43 	struct got_object_id id;
44 
45 	/* Used only during iteration. */
46 	time_t timestamp;
47 	TAILQ_ENTRY(got_commit_graph_node) entry;
48 };
49 
50 TAILQ_HEAD(got_commit_graph_iter_list, got_commit_graph_node);
51 
52 struct got_commit_graph_branch_tip {
53 	struct got_object_id *commit_id;
54 	struct got_commit_object *commit;
55 	struct got_commit_graph_node *new_node;
56 };
57 
58 struct got_commit_graph {
59 	/* The set of all commits we have traversed. */
60 	struct got_object_idset *node_ids;
61 
62 	int flags;
63 #define GOT_COMMIT_GRAPH_FIRST_PARENT_TRAVERSAL		0x01
64 
65 	/*
66 	 * A set of object IDs of known parent commits which we have not yet
67 	 * traversed. Each commit ID in this set represents a branch in commit
68 	 * history: Either the first-parent branch of the head node, or another
69 	 * branch corresponding to a traversed merge commit for which we have
70 	 * not traversed a branch point commit yet.
71 	 *
72 	 * Whenever we add a commit with a matching ID to the graph, we remove
73 	 * its corresponding element from this set, and add new elements for
74 	 * each of that commit's parent commits which were not traversed yet.
75 	 *
76 	 * When API users ask us to fetch more commits, we fetch commits from
77 	 * all currently open branches. This allows API users to process
78 	 * commits in linear order even though the history contains branches.
79 	 */
80 	struct got_object_idset *open_branches;
81 
82 	/* Array of branch tips for fetch_commits_from_open_branches(). */
83 	struct got_commit_graph_branch_tip *tips;
84 	int ntips;
85 
86 	/* Path of tree entry of interest to the API user. */
87 	char *path;
88 
89 	/*
90 	 * Nodes which will be passed to the API user next, sorted by
91 	 * commit timestmap.
92 	 */
93 	struct got_commit_graph_iter_list iter_list;
94 };
95 
96 static const struct got_error *
97 detect_changed_path(int *changed, struct got_commit_object *commit,
98     struct got_object_id *commit_id, const char *path,
99     struct got_repository *repo)
100 {
101 	const struct got_error *err = NULL;
102 	struct got_commit_object *pcommit = NULL;
103 	struct got_tree_object *tree = NULL, *ptree = NULL;
104 	struct got_object_qid *pid;
105 
106 	if (got_path_is_root_dir(path)) {
107 		*changed = 1;
108 		return NULL;
109 	}
110 
111 	*changed = 0;
112 
113 	pid = STAILQ_FIRST(&commit->parent_ids);
114 	if (pid == NULL) {
115 		struct got_object_id *obj_id;
116 		err = got_object_id_by_path(&obj_id, repo, commit, path);
117 		if (err) {
118 			if (err->code == GOT_ERR_NO_TREE_ENTRY)
119 				err = NULL;
120 		} else
121 			*changed = 1; /* The path was created in this commit. */
122 		free(obj_id);
123 		return err;
124 	}
125 
126 	err = got_object_open_as_tree(&tree, repo, commit->tree_id);
127 	if (err)
128 		return err;
129 
130 	err = got_object_open_as_commit(&pcommit, repo, &pid->id);
131 	if (err)
132 		goto done;
133 
134 	err = got_object_open_as_tree(&ptree, repo, pcommit->tree_id);
135 	if (err)
136 		goto done;
137 
138 	err = got_object_tree_path_changed(changed, tree, ptree, path, repo);
139 done:
140 	if (tree)
141 		got_object_tree_close(tree);
142 	if (ptree)
143 		got_object_tree_close(ptree);
144 	if (pcommit)
145 		got_object_commit_close(pcommit);
146 	return err;
147 }
148 
149 static void
150 add_node_to_iter_list(struct got_commit_graph *graph,
151     struct got_commit_graph_node *node, time_t committer_time)
152 {
153 	struct got_commit_graph_node *n, *next;
154 
155 	node->timestamp = committer_time;
156 
157 	n = TAILQ_FIRST(&graph->iter_list);
158 	while (n) {
159 		next = TAILQ_NEXT(n, entry);
160 		if (next && node->timestamp >= next->timestamp) {
161 			TAILQ_INSERT_BEFORE(next, node, entry);
162 			return;
163 		}
164 		n = next;
165 	}
166 	TAILQ_INSERT_TAIL(&graph->iter_list, node, entry);
167 }
168 
169 static const struct got_error *
170 add_node(struct got_commit_graph_node **new_node,
171     struct got_commit_graph *graph, struct got_object_id *commit_id,
172     struct got_repository *repo)
173 {
174 	const struct got_error *err = NULL;
175 	struct got_commit_graph_node *node;
176 
177 	*new_node = NULL;
178 
179 	node = calloc(1, sizeof(*node));
180 	if (node == NULL)
181 		return got_error_from_errno("calloc");
182 
183 	memcpy(&node->id, commit_id, sizeof(node->id));
184 	err = got_object_idset_add(graph->node_ids, &node->id, NULL);
185 	if (err)
186 		free(node);
187 	else
188 		*new_node = node;
189 	return err;
190 }
191 
192 /*
193  * Ask got-read-pack to traverse first-parent history until a commit is
194  * encountered which modified graph->path, or until the pack file runs
195  * out of relevant commits. This is faster than sending an individual
196  * request for each commit stored in the pack file.
197  */
198 static const struct got_error *
199 packed_first_parent_traversal(int *ncommits_traversed,
200     struct got_commit_graph *graph, struct got_object_id *commit_id,
201     struct got_repository *repo)
202 {
203 	const struct got_error *err = NULL;
204 	struct got_object_id_queue traversed_commits;
205 	struct got_object_qid *qid;
206 
207 	STAILQ_INIT(&traversed_commits);
208 	*ncommits_traversed = 0;
209 
210 	err = got_traverse_packed_commits(&traversed_commits,
211 	    commit_id, graph->path, repo);
212 	if (err)
213 		return err;
214 
215 	/* Add all traversed commits to the graph... */
216 	STAILQ_FOREACH(qid, &traversed_commits, entry) {
217 		if (got_object_idset_contains(graph->open_branches, &qid->id))
218 			continue;
219 		if (got_object_idset_contains(graph->node_ids, &qid->id))
220 			continue;
221 
222 		(*ncommits_traversed)++;
223 
224 		/* ... except the last commit is the new branch tip. */
225 		if (STAILQ_NEXT(qid, entry) == NULL) {
226 			err = got_object_idset_add(graph->open_branches,
227 			    &qid->id, NULL);
228 			break;
229 		}
230 
231 		err = got_object_idset_add(graph->node_ids, &qid->id, NULL);
232 		if (err)
233 			break;
234 	}
235 
236 	got_object_id_queue_free(&traversed_commits);
237 	return err;
238 }
239 
240 static const struct got_error *
241 close_branch(struct got_commit_graph *graph, struct got_object_id *commit_id)
242 {
243 	const struct got_error *err;
244 
245 	err = got_object_idset_remove(NULL, graph->open_branches, commit_id);
246 	if (err && err->code != GOT_ERR_NO_OBJ)
247 		return err;
248 	return NULL;
249 }
250 
251 static const struct got_error *
252 advance_branch(struct got_commit_graph *graph, struct got_object_id *commit_id,
253     struct got_commit_object *commit, struct got_repository *repo)
254 {
255 	const struct got_error *err;
256 	struct got_object_qid *qid;
257 	struct got_object_id *merged_id = NULL;
258 
259 	err = close_branch(graph, commit_id);
260 	if (err)
261 		return err;
262 
263 	if (graph->flags & GOT_COMMIT_GRAPH_FIRST_PARENT_TRAVERSAL) {
264 		qid = STAILQ_FIRST(&commit->parent_ids);
265 		if (qid == NULL ||
266 		    got_object_idset_contains(graph->open_branches, &qid->id))
267 			return NULL;
268 		/*
269 		 * The root directory always changes by definition, and when
270 		 * logging the root we want to traverse consecutive commits
271 		 * even if they point at the same tree.
272 		 * But if we are looking for a specific path then we can avoid
273 		 * fetching packed commits which did not modify the path and
274 		 * only fetch their IDs. This speeds up 'got blame'.
275 		 */
276 		if (!got_path_is_root_dir(graph->path) &&
277 		    (commit->flags & GOT_COMMIT_FLAG_PACKED)) {
278 			int ncommits = 0;
279 			err = packed_first_parent_traversal(&ncommits,
280 			    graph, &qid->id, repo);
281 			if (err || ncommits > 0)
282 				return err;
283 		}
284 		return got_object_idset_add(graph->open_branches,
285 		    &qid->id, NULL);
286 	}
287 
288 	/*
289 	 * If we are graphing commits for a specific path, skip branches
290 	 * which do not contribute any content to this path.
291 	 */
292 	if (commit->nparents > 1 && !got_path_is_root_dir(graph->path)) {
293 		err = got_object_id_by_path(&merged_id, repo, commit, graph->path);
294 		if (err && err->code != GOT_ERR_NO_TREE_ENTRY)
295 			return err;
296 		/* The requested path does not exist in this merge commit. */
297 	}
298 	if (commit->nparents > 1 && !got_path_is_root_dir(graph->path) &&
299 	    merged_id != NULL) {
300 		struct got_object_id *prev_id = NULL;
301 		int branches_differ = 0;
302 
303 
304 		STAILQ_FOREACH(qid, &commit->parent_ids, entry) {
305 			struct got_object_id *id = NULL;
306 			struct got_commit_object *pcommit = NULL;
307 
308 			if (got_object_idset_contains(graph->open_branches,
309 			    &qid->id))
310 				continue;
311 
312 			err = got_object_open_as_commit(&pcommit, repo,
313 			    &qid->id);
314 			if (err) {
315 				free(merged_id);
316 				free(prev_id);
317 				return err;
318 			}
319 			err = got_object_id_by_path(&id, repo, pcommit,
320 			    graph->path);
321 			got_object_commit_close(pcommit);
322 			pcommit = NULL;
323 			if (err) {
324 				if (err->code == GOT_ERR_NO_TREE_ENTRY) {
325 					branches_differ = 1;
326 					continue;
327 				}
328 				free(merged_id);
329 				free(prev_id);
330 				return err;
331 			}
332 
333 			if (prev_id) {
334 				if (!branches_differ &&
335 				    got_object_id_cmp(id, prev_id) != 0)
336 					branches_differ = 1;
337 				free(prev_id);
338 			}
339 			prev_id = id;
340 
341 			/*
342 			 * If a branch has created the merged content we can
343 			 * skip any other branches.
344 			 */
345 			if (got_object_id_cmp(merged_id, id) == 0) {
346 				err = got_object_idset_add(graph->open_branches,
347 				    &qid->id, NULL);
348 				free(merged_id);
349 				free(id);
350 				return err;
351 			}
352 		}
353 
354 		free(prev_id);
355 		prev_id = NULL;
356 		free(merged_id);
357 		merged_id = NULL;
358 
359 		/*
360 		 * If the path's content is the same on all branches,
361 		 * follow the first parent only.
362 		 */
363 		if (!branches_differ) {
364 			qid = STAILQ_FIRST(&commit->parent_ids);
365 			if (qid == NULL)
366 				return NULL;
367 			if (got_object_idset_contains(graph->open_branches,
368 			    &qid->id))
369 				return NULL;
370 			if (got_object_idset_contains(graph->node_ids,
371 			    &qid->id))
372 				return NULL; /* parent already traversed */
373 			return got_object_idset_add(graph->open_branches,
374 			    &qid->id, NULL);
375 		}
376 	}
377 
378 	STAILQ_FOREACH(qid, &commit->parent_ids, entry) {
379 		if (got_object_idset_contains(graph->open_branches, &qid->id))
380 			continue;
381 		if (got_object_idset_contains(graph->node_ids, &qid->id))
382 			continue; /* parent already traversed */
383 		err = got_object_idset_add(graph->open_branches, &qid->id,
384 		    NULL);
385 		if (err)
386 			return err;
387 	}
388 
389 	return NULL;
390 }
391 
392 const struct got_error *
393 got_commit_graph_open(struct got_commit_graph **graph,
394     const char *path, int first_parent_traversal)
395 {
396 	const struct got_error *err = NULL;
397 
398 	*graph = calloc(1, sizeof(**graph));
399 	if (*graph == NULL)
400 		return got_error_from_errno("calloc");
401 
402 	TAILQ_INIT(&(*graph)->iter_list);
403 
404 	(*graph)->path = strdup(path);
405 	if ((*graph)->path == NULL) {
406 		err = got_error_from_errno("strdup");
407 		goto done;
408 	}
409 
410 	(*graph)->node_ids = got_object_idset_alloc();
411 	if ((*graph)->node_ids == NULL) {
412 		err = got_error_from_errno("got_object_idset_alloc");
413 		goto done;
414 	}
415 
416 	(*graph)->open_branches = got_object_idset_alloc();
417 	if ((*graph)->open_branches == NULL) {
418 		err = got_error_from_errno("got_object_idset_alloc");
419 		goto done;
420 	}
421 
422 	if (first_parent_traversal)
423 		(*graph)->flags |= GOT_COMMIT_GRAPH_FIRST_PARENT_TRAVERSAL;
424 done:
425 	if (err) {
426 		got_commit_graph_close(*graph);
427 		*graph = NULL;
428 	}
429 	return err;
430 }
431 
432 struct add_branch_tip_arg {
433 	struct got_commit_graph_branch_tip *tips;
434 	int ntips;
435 	struct got_repository *repo;
436 	struct got_commit_graph *graph;
437 };
438 
439 static const struct got_error *
440 add_branch_tip(struct got_object_id *commit_id, void *data, void *arg)
441 {
442 	const struct got_error *err;
443 	struct add_branch_tip_arg *a = arg;
444 	struct got_commit_graph_node *new_node;
445 	struct got_commit_object *commit;
446 
447 	err = got_object_open_as_commit(&commit, a->repo, commit_id);
448 	if (err)
449 		return err;
450 
451 	err = add_node(&new_node, a->graph, commit_id, a->repo);
452 	if (err) {
453 		got_object_commit_close(commit);
454 		return err;
455 	}
456 
457 	a->tips[a->ntips].commit_id = &new_node->id;
458 	a->tips[a->ntips].commit = commit;
459 	a->tips[a->ntips].new_node = new_node;
460 	a->ntips++;
461 
462 	return NULL;
463 }
464 
465 static const struct got_error *
466 fetch_commits_from_open_branches(struct got_commit_graph *graph,
467     struct got_repository *repo, got_cancel_cb cancel_cb, void *cancel_arg)
468 {
469 	const struct got_error *err;
470 	struct add_branch_tip_arg arg;
471 	int i, ntips;
472 
473 	ntips = got_object_idset_num_elements(graph->open_branches);
474 	if (ntips == 0)
475 		return NULL;
476 
477 	/* (Re-)allocate branch tips array if necessary. */
478 	if (graph->ntips < ntips) {
479 		struct got_commit_graph_branch_tip *tips;
480 		tips = recallocarray(graph->tips, graph->ntips, ntips,
481 		    sizeof(*tips));
482 		if (tips == NULL)
483 			return got_error_from_errno("recallocarray");
484 		graph->tips = tips;
485 		graph->ntips = ntips;
486 	}
487 	arg.tips = graph->tips;
488 	arg.ntips = 0; /* add_branch_tip() will increment */
489 	arg.repo = repo;
490 	arg.graph = graph;
491 	err = got_object_idset_for_each(graph->open_branches, add_branch_tip,
492 	    &arg);
493 	if (err)
494 		goto done;
495 
496 	for (i = 0; i < arg.ntips; i++) {
497 		struct got_object_id *commit_id;
498 		struct got_commit_object *commit;
499 		struct got_commit_graph_node *new_node;
500 		int changed;
501 
502 		if (cancel_cb) {
503 			err = (*cancel_cb)(cancel_arg);
504 			if (err)
505 				break;
506 		}
507 
508 		commit_id = arg.tips[i].commit_id;
509 		commit = arg.tips[i].commit;
510 		new_node = arg.tips[i].new_node;
511 
512 		err = detect_changed_path(&changed, commit, commit_id,
513 		    graph->path, repo);
514 		if (err) {
515 			if (err->code != GOT_ERR_NO_OBJ)
516 				break;
517 			/*
518 			 * History of the path stops here on the current
519 			 * branch. Keep going on other branches.
520 			 */
521 			err = close_branch(graph, commit_id);
522 			if (err)
523 				break;
524 			continue;
525 		}
526 		if (changed) {
527 			add_node_to_iter_list(graph, new_node,
528 			    got_object_commit_get_committer_time(commit));
529 			arg.tips[i].new_node = NULL;
530 		}
531 		err = advance_branch(graph, commit_id, commit, repo);
532 		if (err)
533 			break;
534 	}
535 done:
536 	for (i = 0; i < arg.ntips; i++) {
537 		got_object_commit_close(arg.tips[i].commit);
538 		free(arg.tips[i].new_node);
539 	}
540 	return err;
541 }
542 
543 void
544 got_commit_graph_close(struct got_commit_graph *graph)
545 {
546 	struct got_commit_graph_node *node;
547 
548 	while ((node = TAILQ_FIRST(&graph->iter_list))) {
549 		TAILQ_REMOVE(&graph->iter_list, node, entry);
550 		free(node);
551 	}
552 
553 	if (graph->open_branches)
554 		got_object_idset_free(graph->open_branches);
555 	if (graph->node_ids)
556 		got_object_idset_free(graph->node_ids);
557 	free(graph->tips);
558 	free(graph->path);
559 	free(graph);
560 }
561 
562 const struct got_error *
563 got_commit_graph_iter_start(struct got_commit_graph *graph,
564     struct got_object_id *id, struct got_repository *repo,
565     got_cancel_cb cancel_cb, void *cancel_arg)
566 {
567 	const struct got_error *err = NULL;
568 
569 	if (!TAILQ_EMPTY(&graph->iter_list))
570 		return got_error(GOT_ERR_ITER_BUSY);
571 
572 	err = got_object_idset_add(graph->open_branches, id, NULL);
573 	if (err)
574 		return err;
575 
576 	/* Locate first commit which changed graph->path. */
577 	while (TAILQ_EMPTY(&graph->iter_list) &&
578 	    got_object_idset_num_elements(graph->open_branches) > 0) {
579 		err = fetch_commits_from_open_branches(graph, repo,
580 		    cancel_cb, cancel_arg);
581 		if (err)
582 			return err;
583 	}
584 
585 	if (TAILQ_EMPTY(&graph->iter_list)) {
586 		const char *path;
587 		if (got_path_is_root_dir(graph->path))
588 			return got_error_no_obj(id);
589 		path = graph->path;
590 		while (path[0] == '/')
591 			path++;
592 		return got_error_path(path, GOT_ERR_NO_TREE_ENTRY);
593 	}
594 
595 	return NULL;
596 }
597 
598 const struct got_error *
599 got_commit_graph_iter_next(struct got_object_id *id,
600     struct got_commit_graph *graph, struct got_repository *repo,
601     got_cancel_cb cancel_cb, void *cancel_arg)
602 {
603 	const struct got_error *err = NULL;
604 	struct got_commit_graph_node *node;
605 
606 	node = TAILQ_FIRST(&graph->iter_list);
607 	if (node == NULL) {
608 		/* We are done iterating, or iteration was not started. */
609 		return got_error(GOT_ERR_ITER_COMPLETED);
610 	}
611 
612 	while (TAILQ_NEXT(node, entry) == NULL &&
613 	    got_object_idset_num_elements(graph->open_branches) > 0) {
614 		err = fetch_commits_from_open_branches(graph, repo,
615 		    cancel_cb, cancel_arg);
616 		if (err)
617 			return err;
618 	}
619 
620 	memcpy(id, &node->id, sizeof(*id));
621 
622 	TAILQ_REMOVE(&graph->iter_list, node, entry);
623 	free(node);
624 	return NULL;
625 }
626 
627 static const struct got_error *
628 find_yca_add_id(struct got_object_id **yca_id, struct got_commit_graph *graph,
629     struct got_object_idset *commit_ids, struct got_repository *repo,
630     got_cancel_cb cancel_cb, void *cancel_arg)
631 {
632 	const struct got_error *err = NULL;
633 	struct got_object_id id;
634 
635 	err = got_commit_graph_iter_next(&id, graph, repo, cancel_cb,
636 	    cancel_arg);
637 	if (err)
638 		return err;
639 
640 	if (got_object_idset_contains(commit_ids, &id)) {
641 		*yca_id = got_object_id_dup(&id);
642 		if (*yca_id == NULL)
643 			err = got_error_from_errno("got_object_id_dup");
644 		return err;
645 	}
646 
647 	return got_object_idset_add(commit_ids, &id, NULL);
648 }
649 
650 /*
651  * Sets *yca_id to the youngest common ancestor of commit_id and
652  * commit_id2. Returns got_error(GOT_ERR_ANCESTRY) if they have no
653  * common ancestors.
654  *
655  * If first_parent_traversal is nonzero, only linear history is considered.
656  */
657 const struct got_error *
658 got_commit_graph_find_youngest_common_ancestor(struct got_object_id **yca_id,
659     struct got_object_id *commit_id, struct got_object_id *commit_id2,
660     int first_parent_traversal,
661     struct got_repository *repo, got_cancel_cb cancel_cb, void *cancel_arg)
662 {
663 	const struct got_error *err = NULL;
664 	struct got_commit_graph *graph = NULL, *graph2 = NULL;
665 	int completed = 0, completed2 = 0;
666 	struct got_object_idset *commit_ids;
667 
668 	*yca_id = NULL;
669 
670 	commit_ids = got_object_idset_alloc();
671 	if (commit_ids == NULL)
672 		return got_error_from_errno("got_object_idset_alloc");
673 
674 	err = got_commit_graph_open(&graph, "/", first_parent_traversal);
675 	if (err)
676 		goto done;
677 
678 	err = got_commit_graph_open(&graph2, "/", first_parent_traversal);
679 	if (err)
680 		goto done;
681 
682 	err = got_commit_graph_iter_start(graph, commit_id, repo,
683 	    cancel_cb, cancel_arg);
684 	if (err)
685 		goto done;
686 
687 	err = got_commit_graph_iter_start(graph2, commit_id2, repo,
688 	    cancel_cb, cancel_arg);
689 	if (err)
690 		goto done;
691 
692 	for (;;) {
693 		if (cancel_cb) {
694 			err = (*cancel_cb)(cancel_arg);
695 			if (err)
696 				break;
697 		}
698 
699 		if (!completed) {
700 			err = find_yca_add_id(yca_id, graph, commit_ids, repo,
701 			    cancel_cb, cancel_arg);
702 			if (err) {
703 				if (err->code != GOT_ERR_ITER_COMPLETED)
704 					break;
705 				err = NULL;
706 				completed = 1;
707 			}
708 			if (*yca_id)
709 				break;
710 		}
711 
712 		if (!completed2) {
713 			err = find_yca_add_id(yca_id, graph2, commit_ids, repo,
714 			    cancel_cb, cancel_arg);
715 			if (err) {
716 				if (err->code != GOT_ERR_ITER_COMPLETED)
717 					break;
718 				err = NULL;
719 				completed2 = 1;
720 			}
721 			if (*yca_id)
722 				break;
723 		}
724 
725 		if (completed && completed2) {
726 			err = got_error(GOT_ERR_ANCESTRY);
727 			break;
728 		}
729 	}
730 done:
731 	got_object_idset_free(commit_ids);
732 	if (graph)
733 		got_commit_graph_close(graph);
734 	if (graph2)
735 		got_commit_graph_close(graph2);
736 	return err;
737 }