1#include "cache.h"
2#include "tag.h"
3#include "blob.h"
4#include "tree.h"
5#include "commit.h"
6#include "diff.h"
7#include "refs.h"
8#include "revision.h"
9
10static char *path_name(struct name_path *path, const char *name)
11{
12 struct name_path *p;
13 char *n, *m;
14 int nlen = strlen(name);
15 int len = nlen + 1;
16
17 for (p = path; p; p = p->up) {
18 if (p->elem_len)
19 len += p->elem_len + 1;
20 }
21 n = xmalloc(len);
22 m = n + len - (nlen + 1);
23 strcpy(m, name);
24 for (p = path; p; p = p->up) {
25 if (p->elem_len) {
26 m -= p->elem_len + 1;
27 memcpy(m, p->elem, p->elem_len);
28 m[p->elem_len] = '/';
29 }
30 }
31 return n;
32}
33
34struct object_list **add_object(struct object *obj,
35 struct object_list **p,
36 struct name_path *path,
37 const char *name)
38{
39 struct object_list *entry = xmalloc(sizeof(*entry));
40 entry->item = obj;
41 entry->next = *p;
42 entry->name = path_name(path, name);
43 *p = entry;
44 return &entry->next;
45}
46
47static void mark_blob_uninteresting(struct blob *blob)
48{
49 if (blob->object.flags & UNINTERESTING)
50 return;
51 blob->object.flags |= UNINTERESTING;
52}
53
54void mark_tree_uninteresting(struct tree *tree)
55{
56 struct object *obj = &tree->object;
57 struct tree_entry_list *entry;
58
59 if (obj->flags & UNINTERESTING)
60 return;
61 obj->flags |= UNINTERESTING;
62 if (!has_sha1_file(obj->sha1))
63 return;
64 if (parse_tree(tree) < 0)
65 die("bad tree %s", sha1_to_hex(obj->sha1));
66 entry = tree->entries;
67 tree->entries = NULL;
68 while (entry) {
69 struct tree_entry_list *next = entry->next;
70 if (entry->directory)
71 mark_tree_uninteresting(entry->item.tree);
72 else
73 mark_blob_uninteresting(entry->item.blob);
74 free(entry);
75 entry = next;
76 }
77}
78
79void mark_parents_uninteresting(struct commit *commit)
80{
81 struct commit_list *parents = commit->parents;
82
83 while (parents) {
84 struct commit *commit = parents->item;
85 if (!(commit->object.flags & UNINTERESTING)) {
86 commit->object.flags |= UNINTERESTING;
87
88 /*
89 * Normally we haven't parsed the parent
90 * yet, so we won't have a parent of a parent
91 * here. However, it may turn out that we've
92 * reached this commit some other way (where it
93 * wasn't uninteresting), in which case we need
94 * to mark its parents recursively too..
95 */
96 if (commit->parents)
97 mark_parents_uninteresting(commit);
98 }
99
100 /*
101 * A missing commit is ok iff its parent is marked
102 * uninteresting.
103 *
104 * We just mark such a thing parsed, so that when
105 * it is popped next time around, we won't be trying
106 * to parse it and get an error.
107 */
108 if (!has_sha1_file(commit->object.sha1))
109 commit->object.parsed = 1;
110 parents = parents->next;
111 }
112}
113
114static void add_pending_object(struct rev_info *revs, struct object *obj, const char *name)
115{
116 add_object(obj, &revs->pending_objects, NULL, name);
117}
118
119static struct commit *get_commit_reference(struct rev_info *revs, const char *name, const unsigned char *sha1, unsigned int flags)
120{
121 struct object *object;
122
123 object = parse_object(sha1);
124 if (!object)
125 die("bad object %s", name);
126
127 /*
128 * Tag object? Look what it points to..
129 */
130 while (object->type == tag_type) {
131 struct tag *tag = (struct tag *) object;
132 object->flags |= flags;
133 if (revs->tag_objects && !(object->flags & UNINTERESTING))
134 add_pending_object(revs, object, tag->tag);
135 object = parse_object(tag->tagged->sha1);
136 if (!object)
137 die("bad object %s", sha1_to_hex(tag->tagged->sha1));
138 }
139
140 /*
141 * Commit object? Just return it, we'll do all the complex
142 * reachability crud.
143 */
144 if (object->type == commit_type) {
145 struct commit *commit = (struct commit *)object;
146 object->flags |= flags;
147 if (parse_commit(commit) < 0)
148 die("unable to parse commit %s", name);
149 if (flags & UNINTERESTING) {
150 mark_parents_uninteresting(commit);
151 revs->limited = 1;
152 }
153 return commit;
154 }
155
156 /*
157 * Tree object? Either mark it uniniteresting, or add it
158 * to the list of objects to look at later..
159 */
160 if (object->type == tree_type) {
161 struct tree *tree = (struct tree *)object;
162 if (!revs->tree_objects)
163 return NULL;
164 if (flags & UNINTERESTING) {
165 mark_tree_uninteresting(tree);
166 return NULL;
167 }
168 add_pending_object(revs, object, "");
169 return NULL;
170 }
171
172 /*
173 * Blob object? You know the drill by now..
174 */
175 if (object->type == blob_type) {
176 struct blob *blob = (struct blob *)object;
177 if (!revs->blob_objects)
178 return NULL;
179 if (flags & UNINTERESTING) {
180 mark_blob_uninteresting(blob);
181 return NULL;
182 }
183 add_pending_object(revs, object, "");
184 return NULL;
185 }
186 die("%s is unknown object", name);
187}
188
189static int everybody_uninteresting(struct commit_list *orig)
190{
191 struct commit_list *list = orig;
192 while (list) {
193 struct commit *commit = list->item;
194 list = list->next;
195 if (commit->object.flags & UNINTERESTING)
196 continue;
197 return 0;
198 }
199 return 1;
200}
201
202static int tree_difference = REV_TREE_SAME;
203
204static void file_add_remove(struct diff_options *options,
205 int addremove, unsigned mode,
206 const unsigned char *sha1,
207 const char *base, const char *path)
208{
209 int diff = REV_TREE_DIFFERENT;
210
211 /*
212 * Is it an add of a new file? It means that the old tree
213 * didn't have it at all, so we will turn "REV_TREE_SAME" ->
214 * "REV_TREE_NEW", but leave any "REV_TREE_DIFFERENT" alone
215 * (and if it already was "REV_TREE_NEW", we'll keep it
216 * "REV_TREE_NEW" of course).
217 */
218 if (addremove == '+') {
219 diff = tree_difference;
220 if (diff != REV_TREE_SAME)
221 return;
222 diff = REV_TREE_NEW;
223 }
224 tree_difference = diff;
225}
226
227static void file_change(struct diff_options *options,
228 unsigned old_mode, unsigned new_mode,
229 const unsigned char *old_sha1,
230 const unsigned char *new_sha1,
231 const char *base, const char *path)
232{
233 tree_difference = REV_TREE_DIFFERENT;
234}
235
236int rev_compare_tree(struct rev_info *revs, struct tree *t1, struct tree *t2)
237{
238 if (!t1)
239 return REV_TREE_NEW;
240 if (!t2)
241 return REV_TREE_DIFFERENT;
242 tree_difference = REV_TREE_SAME;
243 if (diff_tree_sha1(t1->object.sha1, t2->object.sha1, "",
244 &revs->diffopt) < 0)
245 return REV_TREE_DIFFERENT;
246 return tree_difference;
247}
248
249int rev_same_tree_as_empty(struct rev_info *revs, struct tree *t1)
250{
251 int retval;
252 void *tree;
253 struct tree_desc empty, real;
254
255 if (!t1)
256 return 0;
257
258 tree = read_object_with_reference(t1->object.sha1, tree_type, &real.size, NULL);
259 if (!tree)
260 return 0;
261 real.buf = tree;
262
263 empty.buf = "";
264 empty.size = 0;
265
266 tree_difference = 0;
267 retval = diff_tree(&empty, &real, "", &revs->diffopt);
268 free(tree);
269
270 return retval >= 0 && !tree_difference;
271}
272
273static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
274{
275 struct commit_list **pp, *parent;
276 int tree_changed = 0;
277
278 if (!commit->tree)
279 return;
280
281 if (!commit->parents) {
282 if (!rev_same_tree_as_empty(revs, commit->tree))
283 commit->object.flags |= TREECHANGE;
284 return;
285 }
286
287 pp = &commit->parents;
288 while ((parent = *pp) != NULL) {
289 struct commit *p = parent->item;
290
291 parse_commit(p);
292 switch (rev_compare_tree(revs, p->tree, commit->tree)) {
293 case REV_TREE_SAME:
294 if (p->object.flags & UNINTERESTING) {
295 /* Even if a merge with an uninteresting
296 * side branch brought the entire change
297 * we are interested in, we do not want
298 * to lose the other branches of this
299 * merge, so we just keep going.
300 */
301 pp = &parent->next;
302 continue;
303 }
304 parent->next = NULL;
305 commit->parents = parent;
306 return;
307
308 case REV_TREE_NEW:
309 if (revs->remove_empty_trees &&
310 rev_same_tree_as_empty(revs, p->tree)) {
311 /* We are adding all the specified
312 * paths from this parent, so the
313 * history beyond this parent is not
314 * interesting. Remove its parents
315 * (they are grandparents for us).
316 * IOW, we pretend this parent is a
317 * "root" commit.
318 */
319 parse_commit(p);
320 p->parents = NULL;
321 }
322 /* fallthrough */
323 case REV_TREE_DIFFERENT:
324 tree_changed = 1;
325 pp = &parent->next;
326 continue;
327 }
328 die("bad tree compare for commit %s", sha1_to_hex(commit->object.sha1));
329 }
330 if (tree_changed)
331 commit->object.flags |= TREECHANGE;
332}
333
334static void add_parents_to_list(struct rev_info *revs, struct commit *commit, struct commit_list **list)
335{
336 struct commit_list *parent = commit->parents;
337
338 if (commit->object.flags & ADDED)
339 return;
340 commit->object.flags |= ADDED;
341
342 /*
343 * If the commit is uninteresting, don't try to
344 * prune parents - we want the maximal uninteresting
345 * set.
346 *
347 * Normally we haven't parsed the parent
348 * yet, so we won't have a parent of a parent
349 * here. However, it may turn out that we've
350 * reached this commit some other way (where it
351 * wasn't uninteresting), in which case we need
352 * to mark its parents recursively too..
353 */
354 if (commit->object.flags & UNINTERESTING) {
355 while (parent) {
356 struct commit *p = parent->item;
357 parent = parent->next;
358 parse_commit(p);
359 p->object.flags |= UNINTERESTING;
360 if (p->parents)
361 mark_parents_uninteresting(p);
362 if (p->object.flags & SEEN)
363 continue;
364 p->object.flags |= SEEN;
365 insert_by_date(p, list);
366 }
367 return;
368 }
369
370 /*
371 * Ok, the commit wasn't uninteresting. Try to
372 * simplify the commit history and find the parent
373 * that has no differences in the path set if one exists.
374 */
375 if (revs->prune_fn)
376 revs->prune_fn(revs, commit);
377
378 parent = commit->parents;
379 while (parent) {
380 struct commit *p = parent->item;
381
382 parent = parent->next;
383
384 parse_commit(p);
385 if (p->object.flags & SEEN)
386 continue;
387 p->object.flags |= SEEN;
388 insert_by_date(p, list);
389 }
390}
391
392static void limit_list(struct rev_info *revs)
393{
394 struct commit_list *list = revs->commits;
395 struct commit_list *newlist = NULL;
396 struct commit_list **p = &newlist;
397
398 while (list) {
399 struct commit_list *entry = list;
400 struct commit *commit = list->item;
401 struct object *obj = &commit->object;
402
403 list = list->next;
404 free(entry);
405
406 if (revs->max_age != -1 && (commit->date < revs->max_age))
407 obj->flags |= UNINTERESTING;
408 if (revs->unpacked && has_sha1_pack(obj->sha1))
409 obj->flags |= UNINTERESTING;
410 add_parents_to_list(revs, commit, &list);
411 if (obj->flags & UNINTERESTING) {
412 mark_parents_uninteresting(commit);
413 if (everybody_uninteresting(list))
414 break;
415 continue;
416 }
417 if (revs->min_age != -1 && (commit->date > revs->min_age))
418 continue;
419 p = &commit_list_insert(commit, p)->next;
420 }
421 if (revs->boundary) {
422 /* mark the ones that are on the result list first */
423 for (list = newlist; list; list = list->next) {
424 struct commit *commit = list->item;
425 commit->object.flags |= TMP_MARK;
426 }
427 for (list = newlist; list; list = list->next) {
428 struct commit *commit = list->item;
429 struct object *obj = &commit->object;
430 struct commit_list *parent;
431 if (obj->flags & UNINTERESTING)
432 continue;
433 for (parent = commit->parents;
434 parent;
435 parent = parent->next) {
436 struct commit *pcommit = parent->item;
437 if (!(pcommit->object.flags & UNINTERESTING))
438 continue;
439 pcommit->object.flags |= BOUNDARY;
440 if (pcommit->object.flags & TMP_MARK)
441 continue;
442 pcommit->object.flags |= TMP_MARK;
443 p = &commit_list_insert(pcommit, p)->next;
444 }
445 }
446 for (list = newlist; list; list = list->next) {
447 struct commit *commit = list->item;
448 commit->object.flags &= ~TMP_MARK;
449 }
450 }
451 revs->commits = newlist;
452}
453
454static void add_one_commit(struct commit *commit, struct rev_info *revs)
455{
456 if (!commit || (commit->object.flags & SEEN))
457 return;
458 commit->object.flags |= SEEN;
459 commit_list_insert(commit, &revs->commits);
460}
461
462static int all_flags;
463static struct rev_info *all_revs;
464
465static int handle_one_ref(const char *path, const unsigned char *sha1)
466{
467 struct commit *commit = get_commit_reference(all_revs, path, sha1, all_flags);
468 add_one_commit(commit, all_revs);
469 return 0;
470}
471
472static void handle_all(struct rev_info *revs, unsigned flags)
473{
474 all_revs = revs;
475 all_flags = flags;
476 for_each_ref(handle_one_ref);
477}
478
479void init_revisions(struct rev_info *revs)
480{
481 memset(revs, 0, sizeof(*revs));
482 revs->diffopt.recursive = 1;
483 revs->diffopt.add_remove = file_add_remove;
484 revs->diffopt.change = file_change;
485 revs->lifo = 1;
486 revs->dense = 1;
487 revs->prefix = setup_git_directory();
488 revs->max_age = -1;
489 revs->min_age = -1;
490 revs->max_count = -1;
491
492 revs->prune_fn = NULL;
493 revs->prune_data = NULL;
494
495 revs->topo_setter = topo_sort_default_setter;
496 revs->topo_getter = topo_sort_default_getter;
497}
498
499/*
500 * Parse revision information, filling in the "rev_info" structure,
501 * and removing the used arguments from the argument list.
502 *
503 * Returns the number of arguments left that weren't recognized
504 * (which are also moved to the head of the argument list)
505 */
506int setup_revisions(int argc, const char **argv, struct rev_info *revs, const char *def)
507{
508 int i, flags, seen_dashdash;
509 const char **unrecognized = argv + 1;
510 int left = 1;
511
512 init_revisions(revs);
513
514 /* First, search for "--" */
515 seen_dashdash = 0;
516 for (i = 1; i < argc; i++) {
517 const char *arg = argv[i];
518 if (strcmp(arg, "--"))
519 continue;
520 argv[i] = NULL;
521 argc = i;
522 revs->prune_data = get_pathspec(revs->prefix, argv + i + 1);
523 seen_dashdash = 1;
524 break;
525 }
526
527 flags = 0;
528 for (i = 1; i < argc; i++) {
529 struct commit *commit;
530 const char *arg = argv[i];
531 unsigned char sha1[20];
532 char *dotdot;
533 int local_flags;
534
535 if (*arg == '-') {
536 if (!strncmp(arg, "--max-count=", 12)) {
537 revs->max_count = atoi(arg + 12);
538 continue;
539 }
540 /* accept -<digit>, like traditilnal "head" */
541 if ((*arg == '-') && isdigit(arg[1])) {
542 revs->max_count = atoi(arg + 1);
543 continue;
544 }
545 if (!strcmp(arg, "-n")) {
546 if (argc <= i + 1)
547 die("-n requires an argument");
548 revs->max_count = atoi(argv[++i]);
549 continue;
550 }
551 if (!strncmp(arg,"-n",2)) {
552 revs->max_count = atoi(arg + 2);
553 continue;
554 }
555 if (!strncmp(arg, "--max-age=", 10)) {
556 revs->max_age = atoi(arg + 10);
557 continue;
558 }
559 if (!strncmp(arg, "--since=", 8)) {
560 revs->max_age = approxidate(arg + 8);
561 continue;
562 }
563 if (!strncmp(arg, "--after=", 8)) {
564 revs->max_age = approxidate(arg + 8);
565 continue;
566 }
567 if (!strncmp(arg, "--min-age=", 10)) {
568 revs->min_age = atoi(arg + 10);
569 continue;
570 }
571 if (!strncmp(arg, "--before=", 9)) {
572 revs->min_age = approxidate(arg + 9);
573 continue;
574 }
575 if (!strncmp(arg, "--until=", 8)) {
576 revs->min_age = approxidate(arg + 8);
577 continue;
578 }
579 if (!strcmp(arg, "--all")) {
580 handle_all(revs, flags);
581 continue;
582 }
583 if (!strcmp(arg, "--not")) {
584 flags ^= UNINTERESTING;
585 continue;
586 }
587 if (!strcmp(arg, "--default")) {
588 if (++i >= argc)
589 die("bad --default argument");
590 def = argv[i];
591 continue;
592 }
593 if (!strcmp(arg, "--topo-order")) {
594 revs->topo_order = 1;
595 continue;
596 }
597 if (!strcmp(arg, "--date-order")) {
598 revs->lifo = 0;
599 revs->topo_order = 1;
600 continue;
601 }
602 if (!strcmp(arg, "--parents")) {
603 revs->parents = 1;
604 continue;
605 }
606 if (!strcmp(arg, "--dense")) {
607 revs->dense = 1;
608 continue;
609 }
610 if (!strcmp(arg, "--sparse")) {
611 revs->dense = 0;
612 continue;
613 }
614 if (!strcmp(arg, "--remove-empty")) {
615 revs->remove_empty_trees = 1;
616 continue;
617 }
618 if (!strcmp(arg, "--no-merges")) {
619 revs->no_merges = 1;
620 continue;
621 }
622 if (!strcmp(arg, "--boundary")) {
623 revs->boundary = 1;
624 continue;
625 }
626 if (!strcmp(arg, "--objects")) {
627 revs->tag_objects = 1;
628 revs->tree_objects = 1;
629 revs->blob_objects = 1;
630 continue;
631 }
632 if (!strcmp(arg, "--objects-edge")) {
633 revs->tag_objects = 1;
634 revs->tree_objects = 1;
635 revs->blob_objects = 1;
636 revs->edge_hint = 1;
637 continue;
638 }
639 if (!strcmp(arg, "--unpacked")) {
640 revs->unpacked = 1;
641 continue;
642 }
643 *unrecognized++ = arg;
644 left++;
645 continue;
646 }
647 dotdot = strstr(arg, "..");
648 if (dotdot) {
649 unsigned char from_sha1[20];
650 const char *next = dotdot + 2;
651 const char *this = arg;
652 *dotdot = 0;
653 if (!*next)
654 next = "HEAD";
655 if (dotdot == arg)
656 this = "HEAD";
657 if (!get_sha1(this, from_sha1) &&
658 !get_sha1(next, sha1)) {
659 struct commit *exclude;
660 struct commit *include;
661
662 exclude = get_commit_reference(revs, this, from_sha1, flags ^ UNINTERESTING);
663 include = get_commit_reference(revs, next, sha1, flags);
664 if (!exclude || !include)
665 die("Invalid revision range %s..%s", arg, next);
666 add_one_commit(exclude, revs);
667 add_one_commit(include, revs);
668 continue;
669 }
670 *dotdot = '.';
671 }
672 local_flags = 0;
673 if (*arg == '^') {
674 local_flags = UNINTERESTING;
675 arg++;
676 }
677 if (get_sha1(arg, sha1) < 0) {
678 struct stat st;
679 int j;
680
681 if (seen_dashdash || local_flags)
682 die("bad revision '%s'", arg);
683
684 /* If we didn't have a "--", all filenames must exist */
685 for (j = i; j < argc; j++) {
686 if (lstat(argv[j], &st) < 0)
687 die("'%s': %s", argv[j], strerror(errno));
688 }
689 revs->prune_data = get_pathspec(revs->prefix, argv + i);
690 break;
691 }
692 commit = get_commit_reference(revs, arg, sha1, flags ^ local_flags);
693 add_one_commit(commit, revs);
694 }
695 if (def && !revs->commits) {
696 unsigned char sha1[20];
697 struct commit *commit;
698 if (get_sha1(def, sha1) < 0)
699 die("bad default revision '%s'", def);
700 commit = get_commit_reference(revs, def, sha1, 0);
701 add_one_commit(commit, revs);
702 }
703
704 if (revs->topo_order || revs->unpacked)
705 revs->limited = 1;
706
707 if (revs->prune_data) {
708 diff_tree_setup_paths(revs->prune_data, &revs->diffopt);
709 revs->prune_fn = try_to_simplify_commit;
710 }
711
712 return left;
713}
714
715void prepare_revision_walk(struct rev_info *revs)
716{
717 sort_by_date(&revs->commits);
718 if (revs->limited)
719 limit_list(revs);
720 if (revs->topo_order)
721 sort_in_topological_order_fn(&revs->commits, revs->lifo,
722 revs->topo_setter,
723 revs->topo_getter);
724}
725
726static int rewrite_one(struct rev_info *revs, struct commit **pp)
727{
728 for (;;) {
729 struct commit *p = *pp;
730 if (!revs->limited)
731 add_parents_to_list(revs, p, &revs->commits);
732 if (p->object.flags & (TREECHANGE | UNINTERESTING))
733 return 0;
734 if (!p->parents)
735 return -1;
736 *pp = p->parents->item;
737 }
738}
739
740static void rewrite_parents(struct rev_info *revs, struct commit *commit)
741{
742 struct commit_list **pp = &commit->parents;
743 while (*pp) {
744 struct commit_list *parent = *pp;
745 if (rewrite_one(revs, &parent->item) < 0) {
746 *pp = parent->next;
747 continue;
748 }
749 pp = &parent->next;
750 }
751}
752
753static void mark_boundary_to_show(struct commit *commit)
754{
755 struct commit_list *p = commit->parents;
756 while (p) {
757 commit = p->item;
758 p = p->next;
759 if (commit->object.flags & BOUNDARY)
760 commit->object.flags |= BOUNDARY_SHOW;
761 }
762}
763
764struct commit *get_revision(struct rev_info *revs)
765{
766 struct commit_list *list = revs->commits;
767
768 if (!list)
769 return NULL;
770
771 /* Check the max_count ... */
772 switch (revs->max_count) {
773 case -1:
774 break;
775 case 0:
776 return NULL;
777 default:
778 revs->max_count--;
779 }
780
781 do {
782 struct commit *commit = revs->commits->item;
783
784 revs->commits = revs->commits->next;
785
786 /*
787 * If we haven't done the list limiting, we need to look at
788 * the parents here. We also need to do the date-based limiting
789 * that we'd otherwise have done in limit_list().
790 */
791 if (!revs->limited) {
792 if ((revs->unpacked &&
793 has_sha1_pack(commit->object.sha1)) ||
794 (revs->max_age != -1 &&
795 (commit->date < revs->max_age)))
796 continue;
797 add_parents_to_list(revs, commit, &revs->commits);
798 }
799 if (commit->object.flags & SHOWN)
800 continue;
801
802 /* We want to show boundary commits only when their
803 * children are shown. When path-limiter is in effect,
804 * rewrite_parents() drops some commits from getting shown,
805 * and there is no point showing boundary parents that
806 * are not shown. After rewrite_parents() rewrites the
807 * parents of a commit that is shown, we mark the boundary
808 * parents with BOUNDARY_SHOW.
809 */
810 if (commit->object.flags & BOUNDARY_SHOW) {
811 commit->object.flags |= SHOWN;
812 return commit;
813 }
814 if (commit->object.flags & UNINTERESTING)
815 continue;
816 if (revs->min_age != -1 && (commit->date > revs->min_age))
817 continue;
818 if (revs->no_merges &&
819 commit->parents && commit->parents->next)
820 continue;
821 if (revs->prune_fn && revs->dense) {
822 if (!(commit->object.flags & TREECHANGE))
823 continue;
824 if (revs->parents)
825 rewrite_parents(revs, commit);
826 }
827 if (revs->boundary)
828 mark_boundary_to_show(commit);
829 commit->object.flags |= SHOWN;
830 return commit;
831 } while (revs->commits);
832 return NULL;
833}