Add a test showing that 'git repack' throws away grafted-away parents
[git/git.git] / commit.c
1 #include "cache.h"
2 #include "tag.h"
3 #include "commit.h"
4 #include "pkt-line.h"
5 #include "utf8.h"
6 #include "diff.h"
7 #include "revision.h"
8
9 int save_commit_buffer = 1;
10
11 const char *commit_type = "commit";
12
13 static struct commit *check_commit(struct object *obj,
14 const unsigned char *sha1,
15 int quiet)
16 {
17 if (obj->type != OBJ_COMMIT) {
18 if (!quiet)
19 error("Object %s is a %s, not a commit",
20 sha1_to_hex(sha1), typename(obj->type));
21 return NULL;
22 }
23 return (struct commit *) obj;
24 }
25
26 struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
27 int quiet)
28 {
29 struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
30
31 if (!obj)
32 return NULL;
33 return check_commit(obj, sha1, quiet);
34 }
35
36 struct commit *lookup_commit_reference(const unsigned char *sha1)
37 {
38 return lookup_commit_reference_gently(sha1, 0);
39 }
40
41 struct commit *lookup_commit(const unsigned char *sha1)
42 {
43 struct object *obj = lookup_object(sha1);
44 if (!obj)
45 return create_object(sha1, OBJ_COMMIT, alloc_commit_node());
46 if (!obj->type)
47 obj->type = OBJ_COMMIT;
48 return check_commit(obj, sha1, 0);
49 }
50
51 static unsigned long parse_commit_date(const char *buf, const char *tail)
52 {
53 unsigned long date;
54 const char *dateptr;
55
56 if (buf + 6 >= tail)
57 return 0;
58 if (memcmp(buf, "author", 6))
59 return 0;
60 while (buf < tail && *buf++ != '\n')
61 /* nada */;
62 if (buf + 9 >= tail)
63 return 0;
64 if (memcmp(buf, "committer", 9))
65 return 0;
66 while (buf < tail && *buf++ != '>')
67 /* nada */;
68 if (buf >= tail)
69 return 0;
70 dateptr = buf;
71 while (buf < tail && *buf++ != '\n')
72 /* nada */;
73 if (buf >= tail)
74 return 0;
75 /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
76 date = strtoul(dateptr, NULL, 10);
77 if (date == ULONG_MAX)
78 date = 0;
79 return date;
80 }
81
82 static struct commit_graft **commit_graft;
83 static int commit_graft_alloc, commit_graft_nr;
84
85 static int commit_graft_pos(const unsigned char *sha1)
86 {
87 int lo, hi;
88 lo = 0;
89 hi = commit_graft_nr;
90 while (lo < hi) {
91 int mi = (lo + hi) / 2;
92 struct commit_graft *graft = commit_graft[mi];
93 int cmp = hashcmp(sha1, graft->sha1);
94 if (!cmp)
95 return mi;
96 if (cmp < 0)
97 hi = mi;
98 else
99 lo = mi + 1;
100 }
101 return -lo - 1;
102 }
103
104 int register_commit_graft(struct commit_graft *graft, int ignore_dups)
105 {
106 int pos = commit_graft_pos(graft->sha1);
107
108 if (0 <= pos) {
109 if (ignore_dups)
110 free(graft);
111 else {
112 free(commit_graft[pos]);
113 commit_graft[pos] = graft;
114 }
115 return 1;
116 }
117 pos = -pos - 1;
118 if (commit_graft_alloc <= ++commit_graft_nr) {
119 commit_graft_alloc = alloc_nr(commit_graft_alloc);
120 commit_graft = xrealloc(commit_graft,
121 sizeof(*commit_graft) *
122 commit_graft_alloc);
123 }
124 if (pos < commit_graft_nr)
125 memmove(commit_graft + pos + 1,
126 commit_graft + pos,
127 (commit_graft_nr - pos - 1) *
128 sizeof(*commit_graft));
129 commit_graft[pos] = graft;
130 return 0;
131 }
132
133 struct commit_graft *read_graft_line(char *buf, int len)
134 {
135 /* The format is just "Commit Parent1 Parent2 ...\n" */
136 int i;
137 struct commit_graft *graft = NULL;
138
139 if (buf[len-1] == '\n')
140 buf[--len] = 0;
141 if (buf[0] == '#' || buf[0] == '\0')
142 return NULL;
143 if ((len + 1) % 41) {
144 bad_graft_data:
145 error("bad graft data: %s", buf);
146 free(graft);
147 return NULL;
148 }
149 i = (len + 1) / 41 - 1;
150 graft = xmalloc(sizeof(*graft) + 20 * i);
151 graft->nr_parent = i;
152 if (get_sha1_hex(buf, graft->sha1))
153 goto bad_graft_data;
154 for (i = 40; i < len; i += 41) {
155 if (buf[i] != ' ')
156 goto bad_graft_data;
157 if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
158 goto bad_graft_data;
159 }
160 return graft;
161 }
162
163 static int read_graft_file(const char *graft_file)
164 {
165 FILE *fp = fopen(graft_file, "r");
166 char buf[1024];
167 if (!fp)
168 return -1;
169 while (fgets(buf, sizeof(buf), fp)) {
170 /* The format is just "Commit Parent1 Parent2 ...\n" */
171 int len = strlen(buf);
172 struct commit_graft *graft = read_graft_line(buf, len);
173 if (!graft)
174 continue;
175 if (register_commit_graft(graft, 1))
176 error("duplicate graft data: %s", buf);
177 }
178 fclose(fp);
179 return 0;
180 }
181
182 static void prepare_commit_graft(void)
183 {
184 static int commit_graft_prepared;
185 char *graft_file;
186
187 if (commit_graft_prepared)
188 return;
189 graft_file = get_graft_file();
190 read_graft_file(graft_file);
191 /* make sure shallows are read */
192 is_repository_shallow();
193 commit_graft_prepared = 1;
194 }
195
196 struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
197 {
198 int pos;
199 prepare_commit_graft();
200 pos = commit_graft_pos(sha1);
201 if (pos < 0)
202 return NULL;
203 return commit_graft[pos];
204 }
205
206 int write_shallow_commits(int fd, int use_pack_protocol)
207 {
208 int i, count = 0;
209 for (i = 0; i < commit_graft_nr; i++)
210 if (commit_graft[i]->nr_parent < 0) {
211 const char *hex =
212 sha1_to_hex(commit_graft[i]->sha1);
213 count++;
214 if (use_pack_protocol)
215 packet_write(fd, "shallow %s", hex);
216 else {
217 if (write_in_full(fd, hex, 40) != 40)
218 break;
219 if (write_in_full(fd, "\n", 1) != 1)
220 break;
221 }
222 }
223 return count;
224 }
225
226 int unregister_shallow(const unsigned char *sha1)
227 {
228 int pos = commit_graft_pos(sha1);
229 if (pos < 0)
230 return -1;
231 if (pos + 1 < commit_graft_nr)
232 memcpy(commit_graft + pos, commit_graft + pos + 1,
233 sizeof(struct commit_graft *)
234 * (commit_graft_nr - pos - 1));
235 commit_graft_nr--;
236 return 0;
237 }
238
239 int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
240 {
241 char *tail = buffer;
242 char *bufptr = buffer;
243 unsigned char parent[20];
244 struct commit_list **pptr;
245 struct commit_graft *graft;
246
247 if (item->object.parsed)
248 return 0;
249 item->object.parsed = 1;
250 tail += size;
251 if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
252 return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
253 if (get_sha1_hex(bufptr + 5, parent) < 0)
254 return error("bad tree pointer in commit %s",
255 sha1_to_hex(item->object.sha1));
256 item->tree = lookup_tree(parent);
257 bufptr += 46; /* "tree " + "hex sha1" + "\n" */
258 pptr = &item->parents;
259
260 graft = lookup_commit_graft(item->object.sha1);
261 while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
262 struct commit *new_parent;
263
264 if (tail <= bufptr + 48 ||
265 get_sha1_hex(bufptr + 7, parent) ||
266 bufptr[47] != '\n')
267 return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
268 bufptr += 48;
269 if (graft)
270 continue;
271 new_parent = lookup_commit(parent);
272 if (new_parent)
273 pptr = &commit_list_insert(new_parent, pptr)->next;
274 }
275 if (graft) {
276 int i;
277 struct commit *new_parent;
278 for (i = 0; i < graft->nr_parent; i++) {
279 new_parent = lookup_commit(graft->parent[i]);
280 if (!new_parent)
281 continue;
282 pptr = &commit_list_insert(new_parent, pptr)->next;
283 }
284 }
285 item->date = parse_commit_date(bufptr, tail);
286
287 return 0;
288 }
289
290 int parse_commit(struct commit *item)
291 {
292 enum object_type type;
293 void *buffer;
294 unsigned long size;
295 int ret;
296
297 if (!item)
298 return -1;
299 if (item->object.parsed)
300 return 0;
301 buffer = read_sha1_file(item->object.sha1, &type, &size);
302 if (!buffer)
303 return error("Could not read %s",
304 sha1_to_hex(item->object.sha1));
305 if (type != OBJ_COMMIT) {
306 free(buffer);
307 return error("Object %s not a commit",
308 sha1_to_hex(item->object.sha1));
309 }
310 ret = parse_commit_buffer(item, buffer, size);
311 if (save_commit_buffer && !ret) {
312 item->buffer = buffer;
313 return 0;
314 }
315 free(buffer);
316 return ret;
317 }
318
319 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
320 {
321 struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
322 new_list->item = item;
323 new_list->next = *list_p;
324 *list_p = new_list;
325 return new_list;
326 }
327
328 unsigned commit_list_count(const struct commit_list *l)
329 {
330 unsigned c = 0;
331 for (; l; l = l->next )
332 c++;
333 return c;
334 }
335
336 void free_commit_list(struct commit_list *list)
337 {
338 while (list) {
339 struct commit_list *temp = list;
340 list = temp->next;
341 free(temp);
342 }
343 }
344
345 struct commit_list * insert_by_date(struct commit *item, struct commit_list **list)
346 {
347 struct commit_list **pp = list;
348 struct commit_list *p;
349 while ((p = *pp) != NULL) {
350 if (p->item->date < item->date) {
351 break;
352 }
353 pp = &p->next;
354 }
355 return commit_list_insert(item, pp);
356 }
357
358
359 void sort_by_date(struct commit_list **list)
360 {
361 struct commit_list *ret = NULL;
362 while (*list) {
363 insert_by_date((*list)->item, &ret);
364 *list = (*list)->next;
365 }
366 *list = ret;
367 }
368
369 struct commit *pop_most_recent_commit(struct commit_list **list,
370 unsigned int mark)
371 {
372 struct commit *ret = (*list)->item;
373 struct commit_list *parents = ret->parents;
374 struct commit_list *old = *list;
375
376 *list = (*list)->next;
377 free(old);
378
379 while (parents) {
380 struct commit *commit = parents->item;
381 if (!parse_commit(commit) && !(commit->object.flags & mark)) {
382 commit->object.flags |= mark;
383 insert_by_date(commit, list);
384 }
385 parents = parents->next;
386 }
387 return ret;
388 }
389
390 void clear_commit_marks(struct commit *commit, unsigned int mark)
391 {
392 while (commit) {
393 struct commit_list *parents;
394
395 if (!(mark & commit->object.flags))
396 return;
397
398 commit->object.flags &= ~mark;
399
400 parents = commit->parents;
401 if (!parents)
402 return;
403
404 while ((parents = parents->next))
405 clear_commit_marks(parents->item, mark);
406
407 commit = commit->parents->item;
408 }
409 }
410
411 struct commit *pop_commit(struct commit_list **stack)
412 {
413 struct commit_list *top = *stack;
414 struct commit *item = top ? top->item : NULL;
415
416 if (top) {
417 *stack = top->next;
418 free(top);
419 }
420 return item;
421 }
422
423 /*
424 * Performs an in-place topological sort on the list supplied.
425 */
426 void sort_in_topological_order(struct commit_list ** list, int lifo)
427 {
428 struct commit_list *next, *orig = *list;
429 struct commit_list *work, **insert;
430 struct commit_list **pptr;
431
432 if (!orig)
433 return;
434 *list = NULL;
435
436 /* Mark them and clear the indegree */
437 for (next = orig; next; next = next->next) {
438 struct commit *commit = next->item;
439 commit->indegree = 1;
440 }
441
442 /* update the indegree */
443 for (next = orig; next; next = next->next) {
444 struct commit_list * parents = next->item->parents;
445 while (parents) {
446 struct commit *parent = parents->item;
447
448 if (parent->indegree)
449 parent->indegree++;
450 parents = parents->next;
451 }
452 }
453
454 /*
455 * find the tips
456 *
457 * tips are nodes not reachable from any other node in the list
458 *
459 * the tips serve as a starting set for the work queue.
460 */
461 work = NULL;
462 insert = &work;
463 for (next = orig; next; next = next->next) {
464 struct commit *commit = next->item;
465
466 if (commit->indegree == 1)
467 insert = &commit_list_insert(commit, insert)->next;
468 }
469
470 /* process the list in topological order */
471 if (!lifo)
472 sort_by_date(&work);
473
474 pptr = list;
475 *list = NULL;
476 while (work) {
477 struct commit *commit;
478 struct commit_list *parents, *work_item;
479
480 work_item = work;
481 work = work_item->next;
482 work_item->next = NULL;
483
484 commit = work_item->item;
485 for (parents = commit->parents; parents ; parents = parents->next) {
486 struct commit *parent=parents->item;
487
488 if (!parent->indegree)
489 continue;
490
491 /*
492 * parents are only enqueued for emission
493 * when all their children have been emitted thereby
494 * guaranteeing topological order.
495 */
496 if (--parent->indegree == 1) {
497 if (!lifo)
498 insert_by_date(parent, &work);
499 else
500 commit_list_insert(parent, &work);
501 }
502 }
503 /*
504 * work_item is a commit all of whose children
505 * have already been emitted. we can emit it now.
506 */
507 commit->indegree = 0;
508 *pptr = work_item;
509 pptr = &work_item->next;
510 }
511 }
512
513 /* merge-base stuff */
514
515 /* bits #0..15 in revision.h */
516 #define PARENT1 (1u<<16)
517 #define PARENT2 (1u<<17)
518 #define STALE (1u<<18)
519 #define RESULT (1u<<19)
520
521 static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
522
523 static struct commit *interesting(struct commit_list *list)
524 {
525 while (list) {
526 struct commit *commit = list->item;
527 list = list->next;
528 if (commit->object.flags & STALE)
529 continue;
530 return commit;
531 }
532 return NULL;
533 }
534
535 static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
536 {
537 struct commit_list *list = NULL;
538 struct commit_list *result = NULL;
539 int i;
540
541 for (i = 0; i < n; i++) {
542 if (one == twos[i])
543 /*
544 * We do not mark this even with RESULT so we do not
545 * have to clean it up.
546 */
547 return commit_list_insert(one, &result);
548 }
549
550 if (parse_commit(one))
551 return NULL;
552 for (i = 0; i < n; i++) {
553 if (parse_commit(twos[i]))
554 return NULL;
555 }
556
557 one->object.flags |= PARENT1;
558 insert_by_date(one, &list);
559 for (i = 0; i < n; i++) {
560 twos[i]->object.flags |= PARENT2;
561 insert_by_date(twos[i], &list);
562 }
563
564 while (interesting(list)) {
565 struct commit *commit;
566 struct commit_list *parents;
567 struct commit_list *n;
568 int flags;
569
570 commit = list->item;
571 n = list->next;
572 free(list);
573 list = n;
574
575 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
576 if (flags == (PARENT1 | PARENT2)) {
577 if (!(commit->object.flags & RESULT)) {
578 commit->object.flags |= RESULT;
579 insert_by_date(commit, &result);
580 }
581 /* Mark parents of a found merge stale */
582 flags |= STALE;
583 }
584 parents = commit->parents;
585 while (parents) {
586 struct commit *p = parents->item;
587 parents = parents->next;
588 if ((p->object.flags & flags) == flags)
589 continue;
590 if (parse_commit(p))
591 return NULL;
592 p->object.flags |= flags;
593 insert_by_date(p, &list);
594 }
595 }
596
597 /* Clean up the result to remove stale ones */
598 free_commit_list(list);
599 list = result; result = NULL;
600 while (list) {
601 struct commit_list *n = list->next;
602 if (!(list->item->object.flags & STALE))
603 insert_by_date(list->item, &result);
604 free(list);
605 list = n;
606 }
607 return result;
608 }
609
610 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
611 {
612 struct commit_list *i, *j, *k, *ret = NULL;
613 struct commit_list **pptr = &ret;
614
615 for (i = in; i; i = i->next) {
616 if (!ret)
617 pptr = &commit_list_insert(i->item, pptr)->next;
618 else {
619 struct commit_list *new = NULL, *end = NULL;
620
621 for (j = ret; j; j = j->next) {
622 struct commit_list *bases;
623 bases = get_merge_bases(i->item, j->item, 1);
624 if (!new)
625 new = bases;
626 else
627 end->next = bases;
628 for (k = bases; k; k = k->next)
629 end = k;
630 }
631 ret = new;
632 }
633 }
634 return ret;
635 }
636
637 struct commit_list *get_merge_bases_many(struct commit *one,
638 int n,
639 struct commit **twos,
640 int cleanup)
641 {
642 struct commit_list *list;
643 struct commit **rslt;
644 struct commit_list *result;
645 int cnt, i, j;
646
647 result = merge_bases_many(one, n, twos);
648 for (i = 0; i < n; i++) {
649 if (one == twos[i])
650 return result;
651 }
652 if (!result || !result->next) {
653 if (cleanup) {
654 clear_commit_marks(one, all_flags);
655 for (i = 0; i < n; i++)
656 clear_commit_marks(twos[i], all_flags);
657 }
658 return result;
659 }
660
661 /* There are more than one */
662 cnt = 0;
663 list = result;
664 while (list) {
665 list = list->next;
666 cnt++;
667 }
668 rslt = xcalloc(cnt, sizeof(*rslt));
669 for (list = result, i = 0; list; list = list->next)
670 rslt[i++] = list->item;
671 free_commit_list(result);
672
673 clear_commit_marks(one, all_flags);
674 for (i = 0; i < n; i++)
675 clear_commit_marks(twos[i], all_flags);
676 for (i = 0; i < cnt - 1; i++) {
677 for (j = i+1; j < cnt; j++) {
678 if (!rslt[i] || !rslt[j])
679 continue;
680 result = merge_bases_many(rslt[i], 1, &rslt[j]);
681 clear_commit_marks(rslt[i], all_flags);
682 clear_commit_marks(rslt[j], all_flags);
683 for (list = result; list; list = list->next) {
684 if (rslt[i] == list->item)
685 rslt[i] = NULL;
686 if (rslt[j] == list->item)
687 rslt[j] = NULL;
688 }
689 }
690 }
691
692 /* Surviving ones in rslt[] are the independent results */
693 result = NULL;
694 for (i = 0; i < cnt; i++) {
695 if (rslt[i])
696 insert_by_date(rslt[i], &result);
697 }
698 free(rslt);
699 return result;
700 }
701
702 struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
703 int cleanup)
704 {
705 return get_merge_bases_many(one, 1, &two, cleanup);
706 }
707
708 int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
709 {
710 if (!with_commit)
711 return 1;
712 while (with_commit) {
713 struct commit *other;
714
715 other = with_commit->item;
716 with_commit = with_commit->next;
717 if (in_merge_bases(other, &commit, 1))
718 return 1;
719 }
720 return 0;
721 }
722
723 int in_merge_bases(struct commit *commit, struct commit **reference, int num)
724 {
725 struct commit_list *bases, *b;
726 int ret = 0;
727
728 if (num == 1)
729 bases = get_merge_bases(commit, *reference, 1);
730 else
731 die("not yet");
732 for (b = bases; b; b = b->next) {
733 if (!hashcmp(commit->object.sha1, b->item->object.sha1)) {
734 ret = 1;
735 break;
736 }
737 }
738
739 free_commit_list(bases);
740 return ret;
741 }
742
743 struct commit_list *reduce_heads(struct commit_list *heads)
744 {
745 struct commit_list *p;
746 struct commit_list *result = NULL, **tail = &result;
747 struct commit **other;
748 size_t num_head, num_other;
749
750 if (!heads)
751 return NULL;
752
753 /* Avoid unnecessary reallocations */
754 for (p = heads, num_head = 0; p; p = p->next)
755 num_head++;
756 other = xcalloc(sizeof(*other), num_head);
757
758 /* For each commit, see if it can be reached by others */
759 for (p = heads; p; p = p->next) {
760 struct commit_list *q, *base;
761
762 /* Do we already have this in the result? */
763 for (q = result; q; q = q->next)
764 if (p->item == q->item)
765 break;
766 if (q)
767 continue;
768
769 num_other = 0;
770 for (q = heads; q; q = q->next) {
771 if (p->item == q->item)
772 continue;
773 other[num_other++] = q->item;
774 }
775 if (num_other)
776 base = get_merge_bases_many(p->item, num_other, other, 1);
777 else
778 base = NULL;
779 /*
780 * If p->item does not have anything common with other
781 * commits, there won't be any merge base. If it is
782 * reachable from some of the others, p->item will be
783 * the merge base. If its history is connected with
784 * others, but p->item is not reachable by others, we
785 * will get something other than p->item back.
786 */
787 if (!base || (base->item != p->item))
788 tail = &(commit_list_insert(p->item, tail)->next);
789 free_commit_list(base);
790 }
791 free(other);
792 return result;
793 }