]> git.ipfire.org Git - thirdparty/git.git/blob - bisect.c
Merge branch 'jk/clone-allow-bare-and-o-together'
[thirdparty/git.git] / bisect.c
1 #include "cache.h"
2 #include "config.h"
3 #include "commit.h"
4 #include "diff.h"
5 #include "revision.h"
6 #include "refs.h"
7 #include "list-objects.h"
8 #include "quote.h"
9 #include "hash-lookup.h"
10 #include "run-command.h"
11 #include "log-tree.h"
12 #include "bisect.h"
13 #include "oid-array.h"
14 #include "strvec.h"
15 #include "commit-slab.h"
16 #include "commit-reach.h"
17 #include "object-store.h"
18 #include "dir.h"
19
20 static struct oid_array good_revs;
21 static struct oid_array skipped_revs;
22
23 static struct object_id *current_bad_oid;
24
25 static const char *argv_checkout[] = {"checkout", "-q", NULL, "--", NULL};
26
27 static const char *term_bad;
28 static const char *term_good;
29
30 /* Remember to update object flag allocation in object.h */
31 #define COUNTED (1u<<16)
32
33 /*
34 * This is a truly stupid algorithm, but it's only
35 * used for bisection, and we just don't care enough.
36 *
37 * We care just barely enough to avoid recursing for
38 * non-merge entries.
39 */
40 static int count_distance(struct commit_list *entry)
41 {
42 int nr = 0;
43
44 while (entry) {
45 struct commit *commit = entry->item;
46 struct commit_list *p;
47
48 if (commit->object.flags & (UNINTERESTING | COUNTED))
49 break;
50 if (!(commit->object.flags & TREESAME))
51 nr++;
52 commit->object.flags |= COUNTED;
53 p = commit->parents;
54 entry = p;
55 if (p) {
56 p = p->next;
57 while (p) {
58 nr += count_distance(p);
59 p = p->next;
60 }
61 }
62 }
63
64 return nr;
65 }
66
67 static void clear_distance(struct commit_list *list)
68 {
69 while (list) {
70 struct commit *commit = list->item;
71 commit->object.flags &= ~COUNTED;
72 list = list->next;
73 }
74 }
75
76 define_commit_slab(commit_weight, int *);
77 static struct commit_weight commit_weight;
78
79 #define DEBUG_BISECT 0
80
81 static inline int weight(struct commit_list *elem)
82 {
83 return **commit_weight_at(&commit_weight, elem->item);
84 }
85
86 static inline void weight_set(struct commit_list *elem, int weight)
87 {
88 **commit_weight_at(&commit_weight, elem->item) = weight;
89 }
90
91 static int count_interesting_parents(struct commit *commit, unsigned bisect_flags)
92 {
93 struct commit_list *p;
94 int count;
95
96 for (count = 0, p = commit->parents; p; p = p->next) {
97 if (!(p->item->object.flags & UNINTERESTING))
98 count++;
99 if (bisect_flags & FIND_BISECTION_FIRST_PARENT_ONLY)
100 break;
101 }
102 return count;
103 }
104
105 static inline int approx_halfway(struct commit_list *p, int nr)
106 {
107 int diff;
108
109 /*
110 * Don't short-cut something we are not going to return!
111 */
112 if (p->item->object.flags & TREESAME)
113 return 0;
114 if (DEBUG_BISECT)
115 return 0;
116 /*
117 * For small number of commits 2 and 3 are halfway of 5, and
118 * 3 is halfway of 6 but 2 and 4 are not.
119 */
120 diff = 2 * weight(p) - nr;
121 switch (diff) {
122 case -1: case 0: case 1:
123 return 1;
124 default:
125 /*
126 * For large number of commits we are not so strict, it's
127 * good enough if it's within ~0.1% of the halfway point,
128 * e.g. 5000 is exactly halfway of 10000, but we consider
129 * the values [4996, 5004] as halfway as well.
130 */
131 if (abs(diff) < nr / 1024)
132 return 1;
133 return 0;
134 }
135 }
136
137 static void show_list(const char *debug, int counted, int nr,
138 struct commit_list *list)
139 {
140 struct commit_list *p;
141
142 if (!DEBUG_BISECT)
143 return;
144
145 fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr);
146
147 for (p = list; p; p = p->next) {
148 struct commit_list *pp;
149 struct commit *commit = p->item;
150 unsigned commit_flags = commit->object.flags;
151 enum object_type type;
152 unsigned long size;
153 char *buf = read_object_file(&commit->object.oid, &type,
154 &size);
155 const char *subject_start;
156 int subject_len;
157
158 fprintf(stderr, "%c%c%c ",
159 (commit_flags & TREESAME) ? ' ' : 'T',
160 (commit_flags & UNINTERESTING) ? 'U' : ' ',
161 (commit_flags & COUNTED) ? 'C' : ' ');
162 if (*commit_weight_at(&commit_weight, p->item))
163 fprintf(stderr, "%3d", weight(p));
164 else
165 fprintf(stderr, "---");
166 fprintf(stderr, " %.*s", 8, oid_to_hex(&commit->object.oid));
167 for (pp = commit->parents; pp; pp = pp->next)
168 fprintf(stderr, " %.*s", 8,
169 oid_to_hex(&pp->item->object.oid));
170
171 subject_len = find_commit_subject(buf, &subject_start);
172 if (subject_len)
173 fprintf(stderr, " %.*s", subject_len, subject_start);
174 fprintf(stderr, "\n");
175 }
176 }
177
178 static struct commit_list *best_bisection(struct commit_list *list, int nr)
179 {
180 struct commit_list *p, *best;
181 int best_distance = -1;
182
183 best = list;
184 for (p = list; p; p = p->next) {
185 int distance;
186 unsigned commit_flags = p->item->object.flags;
187
188 if (commit_flags & TREESAME)
189 continue;
190 distance = weight(p);
191 if (nr - distance < distance)
192 distance = nr - distance;
193 if (distance > best_distance) {
194 best = p;
195 best_distance = distance;
196 }
197 }
198
199 return best;
200 }
201
202 struct commit_dist {
203 struct commit *commit;
204 int distance;
205 };
206
207 static int compare_commit_dist(const void *a_, const void *b_)
208 {
209 struct commit_dist *a, *b;
210
211 a = (struct commit_dist *)a_;
212 b = (struct commit_dist *)b_;
213 if (a->distance != b->distance)
214 return b->distance - a->distance; /* desc sort */
215 return oidcmp(&a->commit->object.oid, &b->commit->object.oid);
216 }
217
218 static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
219 {
220 struct commit_list *p;
221 struct commit_dist *array = xcalloc(nr, sizeof(*array));
222 struct strbuf buf = STRBUF_INIT;
223 int cnt, i;
224
225 for (p = list, cnt = 0; p; p = p->next) {
226 int distance;
227 unsigned commit_flags = p->item->object.flags;
228
229 if (commit_flags & TREESAME)
230 continue;
231 distance = weight(p);
232 if (nr - distance < distance)
233 distance = nr - distance;
234 array[cnt].commit = p->item;
235 array[cnt].distance = distance;
236 cnt++;
237 }
238 QSORT(array, cnt, compare_commit_dist);
239 for (p = list, i = 0; i < cnt; i++) {
240 struct object *obj = &(array[i].commit->object);
241
242 strbuf_reset(&buf);
243 strbuf_addf(&buf, "dist=%d", array[i].distance);
244 add_name_decoration(DECORATION_NONE, buf.buf, obj);
245
246 p->item = array[i].commit;
247 if (i < cnt - 1)
248 p = p->next;
249 }
250 if (p) {
251 free_commit_list(p->next);
252 p->next = NULL;
253 }
254 strbuf_release(&buf);
255 free(array);
256 return list;
257 }
258
259 /*
260 * zero or positive weight is the number of interesting commits it can
261 * reach, including itself. Especially, weight = 0 means it does not
262 * reach any tree-changing commits (e.g. just above uninteresting one
263 * but traversal is with pathspec).
264 *
265 * weight = -1 means it has one parent and its distance is yet to
266 * be computed.
267 *
268 * weight = -2 means it has more than one parent and its distance is
269 * unknown. After running count_distance() first, they will get zero
270 * or positive distance.
271 */
272 static struct commit_list *do_find_bisection(struct commit_list *list,
273 int nr, int *weights,
274 unsigned bisect_flags)
275 {
276 int n, counted;
277 struct commit_list *p;
278
279 counted = 0;
280
281 for (n = 0, p = list; p; p = p->next) {
282 struct commit *commit = p->item;
283 unsigned commit_flags = commit->object.flags;
284
285 *commit_weight_at(&commit_weight, p->item) = &weights[n++];
286 switch (count_interesting_parents(commit, bisect_flags)) {
287 case 0:
288 if (!(commit_flags & TREESAME)) {
289 weight_set(p, 1);
290 counted++;
291 show_list("bisection 2 count one",
292 counted, nr, list);
293 }
294 /*
295 * otherwise, it is known not to reach any
296 * tree-changing commit and gets weight 0.
297 */
298 break;
299 case 1:
300 weight_set(p, -1);
301 break;
302 default:
303 weight_set(p, -2);
304 break;
305 }
306 }
307
308 show_list("bisection 2 initialize", counted, nr, list);
309
310 /*
311 * If you have only one parent in the resulting set
312 * then you can reach one commit more than that parent
313 * can reach. So we do not have to run the expensive
314 * count_distance() for single strand of pearls.
315 *
316 * However, if you have more than one parents, you cannot
317 * just add their distance and one for yourself, since
318 * they usually reach the same ancestor and you would
319 * end up counting them twice that way.
320 *
321 * So we will first count distance of merges the usual
322 * way, and then fill the blanks using cheaper algorithm.
323 */
324 for (p = list; p; p = p->next) {
325 if (p->item->object.flags & UNINTERESTING)
326 continue;
327 if (weight(p) != -2)
328 continue;
329 if (bisect_flags & FIND_BISECTION_FIRST_PARENT_ONLY)
330 BUG("shouldn't be calling count-distance in fp mode");
331 weight_set(p, count_distance(p));
332 clear_distance(list);
333
334 /* Does it happen to be at half-way? */
335 if (!(bisect_flags & FIND_BISECTION_ALL) &&
336 approx_halfway(p, nr))
337 return p;
338 counted++;
339 }
340
341 show_list("bisection 2 count_distance", counted, nr, list);
342
343 while (counted < nr) {
344 for (p = list; p; p = p->next) {
345 struct commit_list *q;
346 unsigned commit_flags = p->item->object.flags;
347
348 if (0 <= weight(p))
349 continue;
350
351 for (q = p->item->parents;
352 q;
353 q = bisect_flags & FIND_BISECTION_FIRST_PARENT_ONLY ? NULL : q->next) {
354 if (q->item->object.flags & UNINTERESTING)
355 continue;
356 if (0 <= weight(q))
357 break;
358 }
359 if (!q)
360 continue;
361
362 /*
363 * weight for p is unknown but q is known.
364 * add one for p itself if p is to be counted,
365 * otherwise inherit it from q directly.
366 */
367 if (!(commit_flags & TREESAME)) {
368 weight_set(p, weight(q)+1);
369 counted++;
370 show_list("bisection 2 count one",
371 counted, nr, list);
372 }
373 else
374 weight_set(p, weight(q));
375
376 /* Does it happen to be at half-way? */
377 if (!(bisect_flags & FIND_BISECTION_ALL) &&
378 approx_halfway(p, nr))
379 return p;
380 }
381 }
382
383 show_list("bisection 2 counted all", counted, nr, list);
384
385 if (!(bisect_flags & FIND_BISECTION_ALL))
386 return best_bisection(list, nr);
387 else
388 return best_bisection_sorted(list, nr);
389 }
390
391 void find_bisection(struct commit_list **commit_list, int *reaches,
392 int *all, unsigned bisect_flags)
393 {
394 int nr, on_list;
395 struct commit_list *list, *p, *best, *next, *last;
396 int *weights;
397
398 show_list("bisection 2 entry", 0, 0, *commit_list);
399 init_commit_weight(&commit_weight);
400
401 /*
402 * Count the number of total and tree-changing items on the
403 * list, while reversing the list.
404 */
405 for (nr = on_list = 0, last = NULL, p = *commit_list;
406 p;
407 p = next) {
408 unsigned commit_flags = p->item->object.flags;
409
410 next = p->next;
411 if (commit_flags & UNINTERESTING) {
412 free(p);
413 continue;
414 }
415 p->next = last;
416 last = p;
417 if (!(commit_flags & TREESAME))
418 nr++;
419 on_list++;
420 }
421 list = last;
422 show_list("bisection 2 sorted", 0, nr, list);
423
424 *all = nr;
425 CALLOC_ARRAY(weights, on_list);
426
427 /* Do the real work of finding bisection commit. */
428 best = do_find_bisection(list, nr, weights, bisect_flags);
429 if (best) {
430 if (!(bisect_flags & FIND_BISECTION_ALL)) {
431 list->item = best->item;
432 free_commit_list(list->next);
433 best = list;
434 best->next = NULL;
435 }
436 *reaches = weight(best);
437 }
438 free(weights);
439 *commit_list = best;
440 clear_commit_weight(&commit_weight);
441 }
442
443 static int register_ref(const char *refname, const struct object_id *oid,
444 int flags UNUSED, void *cb_data UNUSED)
445 {
446 struct strbuf good_prefix = STRBUF_INIT;
447 strbuf_addstr(&good_prefix, term_good);
448 strbuf_addstr(&good_prefix, "-");
449
450 if (!strcmp(refname, term_bad)) {
451 current_bad_oid = xmalloc(sizeof(*current_bad_oid));
452 oidcpy(current_bad_oid, oid);
453 } else if (starts_with(refname, good_prefix.buf)) {
454 oid_array_append(&good_revs, oid);
455 } else if (starts_with(refname, "skip-")) {
456 oid_array_append(&skipped_revs, oid);
457 }
458
459 strbuf_release(&good_prefix);
460
461 return 0;
462 }
463
464 static int read_bisect_refs(void)
465 {
466 return for_each_ref_in("refs/bisect/", register_ref, NULL);
467 }
468
469 static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
470 static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")
471 static GIT_PATH_FUNC(git_path_bisect_ancestors_ok, "BISECT_ANCESTORS_OK")
472 static GIT_PATH_FUNC(git_path_bisect_run, "BISECT_RUN")
473 static GIT_PATH_FUNC(git_path_bisect_start, "BISECT_START")
474 static GIT_PATH_FUNC(git_path_bisect_log, "BISECT_LOG")
475 static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
476 static GIT_PATH_FUNC(git_path_bisect_first_parent, "BISECT_FIRST_PARENT")
477 static GIT_PATH_FUNC(git_path_head_name, "head-name")
478
479 static void read_bisect_paths(struct strvec *array)
480 {
481 struct strbuf str = STRBUF_INIT;
482 const char *filename = git_path_bisect_names();
483 FILE *fp = xfopen(filename, "r");
484
485 while (strbuf_getline_lf(&str, fp) != EOF) {
486 strbuf_trim(&str);
487 if (sq_dequote_to_strvec(str.buf, array))
488 die(_("Badly quoted content in file '%s': %s"),
489 filename, str.buf);
490 }
491
492 strbuf_release(&str);
493 fclose(fp);
494 }
495
496 static char *join_oid_array_hex(struct oid_array *array, char delim)
497 {
498 struct strbuf joined_hexs = STRBUF_INIT;
499 int i;
500
501 for (i = 0; i < array->nr; i++) {
502 strbuf_addstr(&joined_hexs, oid_to_hex(array->oid + i));
503 if (i + 1 < array->nr)
504 strbuf_addch(&joined_hexs, delim);
505 }
506
507 return strbuf_detach(&joined_hexs, NULL);
508 }
509
510 /*
511 * In this function, passing a not NULL skipped_first is very special.
512 * It means that we want to know if the first commit in the list is
513 * skipped because we will want to test a commit away from it if it is
514 * indeed skipped.
515 * So if the first commit is skipped, we cannot take the shortcut to
516 * just "return list" when we find the first non skipped commit, we
517 * have to return a fully filtered list.
518 *
519 * We use (*skipped_first == -1) to mean "it has been found that the
520 * first commit is not skipped". In this case *skipped_first is set back
521 * to 0 just before the function returns.
522 */
523 struct commit_list *filter_skipped(struct commit_list *list,
524 struct commit_list **tried,
525 int show_all,
526 int *count,
527 int *skipped_first)
528 {
529 struct commit_list *filtered = NULL, **f = &filtered;
530
531 *tried = NULL;
532
533 if (skipped_first)
534 *skipped_first = 0;
535 if (count)
536 *count = 0;
537
538 if (!skipped_revs.nr)
539 return list;
540
541 while (list) {
542 struct commit_list *next = list->next;
543 list->next = NULL;
544 if (0 <= oid_array_lookup(&skipped_revs, &list->item->object.oid)) {
545 if (skipped_first && !*skipped_first)
546 *skipped_first = 1;
547 /* Move current to tried list */
548 *tried = list;
549 tried = &list->next;
550 } else {
551 if (!show_all) {
552 if (!skipped_first || !*skipped_first)
553 return list;
554 } else if (skipped_first && !*skipped_first) {
555 /* This means we know it's not skipped */
556 *skipped_first = -1;
557 }
558 /* Move current to filtered list */
559 *f = list;
560 f = &list->next;
561 if (count)
562 (*count)++;
563 }
564 list = next;
565 }
566
567 if (skipped_first && *skipped_first == -1)
568 *skipped_first = 0;
569
570 return filtered;
571 }
572
573 #define PRN_MODULO 32768
574
575 /*
576 * This is a pseudo random number generator based on "man 3 rand".
577 * It is not used properly because the seed is the argument and it
578 * is increased by one between each call, but that should not matter
579 * for this application.
580 */
581 static unsigned get_prn(unsigned count)
582 {
583 count = count * 1103515245 + 12345;
584 return (count/65536) % PRN_MODULO;
585 }
586
587 /*
588 * Custom integer square root from
589 * https://en.wikipedia.org/wiki/Integer_square_root
590 */
591 static int sqrti(int val)
592 {
593 float d, x = val;
594
595 if (!val)
596 return 0;
597
598 do {
599 float y = (x + (float)val / x) / 2;
600 d = (y > x) ? y - x : x - y;
601 x = y;
602 } while (d >= 0.5);
603
604 return (int)x;
605 }
606
607 static struct commit_list *skip_away(struct commit_list *list, int count)
608 {
609 struct commit_list *cur, *previous;
610 int prn, index, i;
611
612 prn = get_prn(count);
613 index = (count * prn / PRN_MODULO) * sqrti(prn) / sqrti(PRN_MODULO);
614
615 cur = list;
616 previous = NULL;
617
618 for (i = 0; cur; cur = cur->next, i++) {
619 if (i == index) {
620 if (!oideq(&cur->item->object.oid, current_bad_oid))
621 return cur;
622 if (previous)
623 return previous;
624 return list;
625 }
626 previous = cur;
627 }
628
629 return list;
630 }
631
632 static struct commit_list *managed_skipped(struct commit_list *list,
633 struct commit_list **tried)
634 {
635 int count, skipped_first;
636
637 *tried = NULL;
638
639 if (!skipped_revs.nr)
640 return list;
641
642 list = filter_skipped(list, tried, 0, &count, &skipped_first);
643
644 if (!skipped_first)
645 return list;
646
647 return skip_away(list, count);
648 }
649
650 static void bisect_rev_setup(struct repository *r, struct rev_info *revs,
651 struct strvec *rev_argv,
652 const char *prefix,
653 const char *bad_format, const char *good_format,
654 int read_paths)
655 {
656 struct setup_revision_opt opt = {
657 .free_removed_argv_elements = 1,
658 };
659 int i;
660
661 repo_init_revisions(r, revs, prefix);
662 revs->abbrev = 0;
663 revs->commit_format = CMIT_FMT_UNSPECIFIED;
664
665 /* rev_argv.argv[0] will be ignored by setup_revisions */
666 strvec_push(rev_argv, "bisect_rev_setup");
667 strvec_pushf(rev_argv, bad_format, oid_to_hex(current_bad_oid));
668 for (i = 0; i < good_revs.nr; i++)
669 strvec_pushf(rev_argv, good_format,
670 oid_to_hex(good_revs.oid + i));
671 strvec_push(rev_argv, "--");
672 if (read_paths)
673 read_bisect_paths(rev_argv);
674
675 setup_revisions(rev_argv->nr, rev_argv->v, revs, &opt);
676 }
677
678 static void bisect_common(struct rev_info *revs)
679 {
680 if (prepare_revision_walk(revs))
681 die("revision walk setup failed");
682 if (revs->tree_objects)
683 mark_edges_uninteresting(revs, NULL, 0);
684 }
685
686 static enum bisect_error error_if_skipped_commits(struct commit_list *tried,
687 const struct object_id *bad)
688 {
689 if (!tried)
690 return BISECT_OK;
691
692 printf("There are only 'skip'ped commits left to test.\n"
693 "The first %s commit could be any of:\n", term_bad);
694
695 for ( ; tried; tried = tried->next)
696 printf("%s\n", oid_to_hex(&tried->item->object.oid));
697
698 if (bad)
699 printf("%s\n", oid_to_hex(bad));
700 printf(_("We cannot bisect more!\n"));
701
702 return BISECT_ONLY_SKIPPED_LEFT;
703 }
704
705 static int is_expected_rev(const struct object_id *oid)
706 {
707 const char *filename = git_path_bisect_expected_rev();
708 struct stat st;
709 struct strbuf str = STRBUF_INIT;
710 FILE *fp;
711 int res = 0;
712
713 if (stat(filename, &st) || !S_ISREG(st.st_mode))
714 return 0;
715
716 fp = fopen_or_warn(filename, "r");
717 if (!fp)
718 return 0;
719
720 if (strbuf_getline_lf(&str, fp) != EOF)
721 res = !strcmp(str.buf, oid_to_hex(oid));
722
723 strbuf_release(&str);
724 fclose(fp);
725
726 return res;
727 }
728
729 enum bisect_error bisect_checkout(const struct object_id *bisect_rev,
730 int no_checkout)
731 {
732 char bisect_rev_hex[GIT_MAX_HEXSZ + 1];
733 struct commit *commit;
734 struct pretty_print_context pp = {0};
735 struct strbuf commit_msg = STRBUF_INIT;
736
737 oid_to_hex_r(bisect_rev_hex, bisect_rev);
738 update_ref(NULL, "BISECT_EXPECTED_REV", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
739
740 argv_checkout[2] = bisect_rev_hex;
741 if (no_checkout) {
742 update_ref(NULL, "BISECT_HEAD", bisect_rev, NULL, 0,
743 UPDATE_REFS_DIE_ON_ERR);
744 } else {
745 if (run_command_v_opt(argv_checkout, RUN_GIT_CMD))
746 /*
747 * Errors in `run_command()` itself, signaled by res < 0,
748 * and errors in the child process, signaled by res > 0
749 * can both be treated as regular BISECT_FAILED (-1).
750 */
751 return BISECT_FAILED;
752 }
753
754 commit = lookup_commit_reference(the_repository, bisect_rev);
755 format_commit_message(commit, "[%H] %s%n", &commit_msg, &pp);
756 fputs(commit_msg.buf, stdout);
757 strbuf_release(&commit_msg);
758
759 return BISECT_OK;
760 }
761
762 static struct commit *get_commit_reference(struct repository *r,
763 const struct object_id *oid)
764 {
765 struct commit *c = lookup_commit_reference(r, oid);
766 if (!c)
767 die(_("Not a valid commit name %s"), oid_to_hex(oid));
768 return c;
769 }
770
771 static struct commit **get_bad_and_good_commits(struct repository *r,
772 int *rev_nr)
773 {
774 struct commit **rev;
775 int i, n = 0;
776
777 ALLOC_ARRAY(rev, 1 + good_revs.nr);
778 rev[n++] = get_commit_reference(r, current_bad_oid);
779 for (i = 0; i < good_revs.nr; i++)
780 rev[n++] = get_commit_reference(r, good_revs.oid + i);
781 *rev_nr = n;
782
783 return rev;
784 }
785
786 static enum bisect_error handle_bad_merge_base(void)
787 {
788 if (is_expected_rev(current_bad_oid)) {
789 char *bad_hex = oid_to_hex(current_bad_oid);
790 char *good_hex = join_oid_array_hex(&good_revs, ' ');
791 if (!strcmp(term_bad, "bad") && !strcmp(term_good, "good")) {
792 fprintf(stderr, _("The merge base %s is bad.\n"
793 "This means the bug has been fixed "
794 "between %s and [%s].\n"),
795 bad_hex, bad_hex, good_hex);
796 } else if (!strcmp(term_bad, "new") && !strcmp(term_good, "old")) {
797 fprintf(stderr, _("The merge base %s is new.\n"
798 "The property has changed "
799 "between %s and [%s].\n"),
800 bad_hex, bad_hex, good_hex);
801 } else {
802 fprintf(stderr, _("The merge base %s is %s.\n"
803 "This means the first '%s' commit is "
804 "between %s and [%s].\n"),
805 bad_hex, term_bad, term_good, bad_hex, good_hex);
806 }
807 return BISECT_MERGE_BASE_CHECK;
808 }
809
810 fprintf(stderr, _("Some %s revs are not ancestors of the %s rev.\n"
811 "git bisect cannot work properly in this case.\n"
812 "Maybe you mistook %s and %s revs?\n"),
813 term_good, term_bad, term_good, term_bad);
814 return BISECT_FAILED;
815 }
816
817 static void handle_skipped_merge_base(const struct object_id *mb)
818 {
819 char *mb_hex = oid_to_hex(mb);
820 char *bad_hex = oid_to_hex(current_bad_oid);
821 char *good_hex = join_oid_array_hex(&good_revs, ' ');
822
823 warning(_("the merge base between %s and [%s] "
824 "must be skipped.\n"
825 "So we cannot be sure the first %s commit is "
826 "between %s and %s.\n"
827 "We continue anyway."),
828 bad_hex, good_hex, term_bad, mb_hex, bad_hex);
829 free(good_hex);
830 }
831
832 /*
833 * "check_merge_bases" checks that merge bases are not "bad" (or "new").
834 *
835 * - If one is "bad" (or "new"), it means the user assumed something wrong
836 * and we must return error with a non 0 error code.
837 * - If one is "good" (or "old"), that's good, we have nothing to do.
838 * - If one is "skipped", we can't know but we should warn.
839 * - If we don't know, we should check it out and ask the user to test.
840 * - If a merge base must be tested, on success return
841 * BISECT_INTERNAL_SUCCESS_MERGE_BASE (-11) a special condition
842 * for early success, this will be converted back to 0 in
843 * check_good_are_ancestors_of_bad().
844 */
845 static enum bisect_error check_merge_bases(int rev_nr, struct commit **rev, int no_checkout)
846 {
847 enum bisect_error res = BISECT_OK;
848 struct commit_list *result;
849
850 result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1);
851
852 for (; result; result = result->next) {
853 const struct object_id *mb = &result->item->object.oid;
854 if (oideq(mb, current_bad_oid)) {
855 res = handle_bad_merge_base();
856 break;
857 } else if (0 <= oid_array_lookup(&good_revs, mb)) {
858 continue;
859 } else if (0 <= oid_array_lookup(&skipped_revs, mb)) {
860 handle_skipped_merge_base(mb);
861 } else {
862 printf(_("Bisecting: a merge base must be tested\n"));
863 res = bisect_checkout(mb, no_checkout);
864 if (!res)
865 /* indicate early success */
866 res = BISECT_INTERNAL_SUCCESS_MERGE_BASE;
867 break;
868 }
869 }
870
871 free_commit_list(result);
872 return res;
873 }
874
875 static int check_ancestors(struct repository *r, int rev_nr,
876 struct commit **rev, const char *prefix)
877 {
878 struct strvec rev_argv = STRVEC_INIT;
879 struct rev_info revs;
880 int res;
881
882 bisect_rev_setup(r, &revs, &rev_argv, prefix, "^%s", "%s", 0);
883
884 bisect_common(&revs);
885 res = (revs.commits != NULL);
886
887 /* Clean up objects used, as they will be reused. */
888 clear_commit_marks_many(rev_nr, rev, ALL_REV_FLAGS);
889
890 release_revisions(&revs);
891 strvec_clear(&rev_argv);
892 return res;
893 }
894
895 /*
896 * "check_good_are_ancestors_of_bad" checks that all "good" revs are
897 * ancestor of the "bad" rev.
898 *
899 * If that's not the case, we need to check the merge bases.
900 * If a merge base must be tested by the user, its source code will be
901 * checked out to be tested by the user and we will return.
902 */
903
904 static enum bisect_error check_good_are_ancestors_of_bad(struct repository *r,
905 const char *prefix,
906 int no_checkout)
907 {
908 char *filename;
909 struct stat st;
910 int fd, rev_nr;
911 enum bisect_error res = BISECT_OK;
912 struct commit **rev;
913
914 if (!current_bad_oid)
915 return error(_("a %s revision is needed"), term_bad);
916
917 filename = git_pathdup("BISECT_ANCESTORS_OK");
918
919 /* Check if file BISECT_ANCESTORS_OK exists. */
920 if (!stat(filename, &st) && S_ISREG(st.st_mode))
921 goto done;
922
923 /* Bisecting with no good rev is ok. */
924 if (!good_revs.nr)
925 goto done;
926
927 /* Check if all good revs are ancestor of the bad rev. */
928
929 rev = get_bad_and_good_commits(r, &rev_nr);
930 if (check_ancestors(r, rev_nr, rev, prefix))
931 res = check_merge_bases(rev_nr, rev, no_checkout);
932 free(rev);
933
934 if (!res) {
935 /* Create file BISECT_ANCESTORS_OK. */
936 fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
937 if (fd < 0)
938 /*
939 * BISECT_ANCESTORS_OK file is not absolutely necessary,
940 * the bisection process will continue at the next
941 * bisection step.
942 * So, just signal with a warning that something
943 * might be wrong.
944 */
945 warning_errno(_("could not create file '%s'"),
946 filename);
947 else
948 close(fd);
949 }
950 done:
951 free(filename);
952 return res;
953 }
954
955 /*
956 * This does "git diff-tree --pretty COMMIT" without one fork+exec.
957 */
958 static void show_diff_tree(struct repository *r,
959 const char *prefix,
960 struct commit *commit)
961 {
962 const char *argv[] = {
963 "diff-tree", "--pretty", "--stat", "--summary", "--cc", NULL
964 };
965 struct rev_info opt;
966
967 git_config(git_diff_ui_config, NULL);
968 repo_init_revisions(r, &opt, prefix);
969
970 setup_revisions(ARRAY_SIZE(argv) - 1, argv, &opt, NULL);
971 log_tree_commit(&opt, commit);
972 release_revisions(&opt);
973 }
974
975 /*
976 * The terms used for this bisect session are stored in BISECT_TERMS.
977 * We read them and store them to adapt the messages accordingly.
978 * Default is bad/good.
979 */
980 void read_bisect_terms(const char **read_bad, const char **read_good)
981 {
982 struct strbuf str = STRBUF_INIT;
983 const char *filename = git_path_bisect_terms();
984 FILE *fp = fopen(filename, "r");
985
986 if (!fp) {
987 if (errno == ENOENT) {
988 *read_bad = "bad";
989 *read_good = "good";
990 return;
991 } else {
992 die_errno(_("could not read file '%s'"), filename);
993 }
994 } else {
995 strbuf_getline_lf(&str, fp);
996 *read_bad = strbuf_detach(&str, NULL);
997 strbuf_getline_lf(&str, fp);
998 *read_good = strbuf_detach(&str, NULL);
999 }
1000 strbuf_release(&str);
1001 fclose(fp);
1002 }
1003
1004 /*
1005 * We use the convention that return BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND (-10) means
1006 * the bisection process finished successfully.
1007 * In this case the calling function or command should not turn a
1008 * BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND return code into an error or a non zero exit code.
1009 *
1010 * Checking BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND
1011 * in bisect_helper::bisect_next() and only transforming it to 0 at
1012 * the end of bisect_helper::cmd_bisect__helper() helps bypassing
1013 * all the code related to finding a commit to test.
1014 */
1015 enum bisect_error bisect_next_all(struct repository *r, const char *prefix)
1016 {
1017 struct strvec rev_argv = STRVEC_INIT;
1018 struct rev_info revs = REV_INFO_INIT;
1019 struct commit_list *tried;
1020 int reaches = 0, all = 0, nr, steps;
1021 enum bisect_error res = BISECT_OK;
1022 struct object_id *bisect_rev;
1023 char *steps_msg;
1024 /*
1025 * If no_checkout is non-zero, the bisection process does not
1026 * checkout the trial commit but instead simply updates BISECT_HEAD.
1027 */
1028 int no_checkout = ref_exists("BISECT_HEAD");
1029 unsigned bisect_flags = 0;
1030
1031 read_bisect_terms(&term_bad, &term_good);
1032 if (read_bisect_refs())
1033 die(_("reading bisect refs failed"));
1034
1035 if (file_exists(git_path_bisect_first_parent()))
1036 bisect_flags |= FIND_BISECTION_FIRST_PARENT_ONLY;
1037
1038 if (skipped_revs.nr)
1039 bisect_flags |= FIND_BISECTION_ALL;
1040
1041 res = check_good_are_ancestors_of_bad(r, prefix, no_checkout);
1042 if (res)
1043 goto cleanup;
1044
1045 bisect_rev_setup(r, &revs, &rev_argv, prefix, "%s", "^%s", 1);
1046
1047 revs.first_parent_only = !!(bisect_flags & FIND_BISECTION_FIRST_PARENT_ONLY);
1048 revs.limited = 1;
1049
1050 bisect_common(&revs);
1051
1052 find_bisection(&revs.commits, &reaches, &all, bisect_flags);
1053 revs.commits = managed_skipped(revs.commits, &tried);
1054
1055 if (!revs.commits) {
1056 /*
1057 * We should return error here only if the "bad"
1058 * commit is also a "skip" commit.
1059 */
1060 res = error_if_skipped_commits(tried, NULL);
1061 if (res < 0)
1062 goto cleanup;
1063 printf(_("%s was both %s and %s\n"),
1064 oid_to_hex(current_bad_oid),
1065 term_good,
1066 term_bad);
1067
1068 res = BISECT_FAILED;
1069 goto cleanup;
1070 }
1071
1072 if (!all) {
1073 fprintf(stderr, _("No testable commit found.\n"
1074 "Maybe you started with bad path arguments?\n"));
1075
1076 res = BISECT_NO_TESTABLE_COMMIT;
1077 goto cleanup;
1078 }
1079
1080 bisect_rev = &revs.commits->item->object.oid;
1081
1082 if (oideq(bisect_rev, current_bad_oid)) {
1083 res = error_if_skipped_commits(tried, current_bad_oid);
1084 if (res)
1085 return res;
1086 printf("%s is the first %s commit\n", oid_to_hex(bisect_rev),
1087 term_bad);
1088
1089 show_diff_tree(r, prefix, revs.commits->item);
1090 /*
1091 * This means the bisection process succeeded.
1092 * Using BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND (-10)
1093 * so that the call chain can simply check
1094 * for negative return values for early returns up
1095 * until the cmd_bisect__helper() caller.
1096 */
1097 res = BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND;
1098 goto cleanup;
1099 }
1100
1101 nr = all - reaches - 1;
1102 steps = estimate_bisect_steps(all);
1103
1104 steps_msg = xstrfmt(Q_("(roughly %d step)", "(roughly %d steps)",
1105 steps), steps);
1106 /*
1107 * TRANSLATORS: the last %s will be replaced with "(roughly %d
1108 * steps)" translation.
1109 */
1110 printf(Q_("Bisecting: %d revision left to test after this %s\n",
1111 "Bisecting: %d revisions left to test after this %s\n",
1112 nr), nr, steps_msg);
1113 free(steps_msg);
1114 /* Clean up objects used, as they will be reused. */
1115 repo_clear_commit_marks(r, ALL_REV_FLAGS);
1116
1117 res = bisect_checkout(bisect_rev, no_checkout);
1118 cleanup:
1119 release_revisions(&revs);
1120 strvec_clear(&rev_argv);
1121 return res;
1122 }
1123
1124 static inline int log2i(int n)
1125 {
1126 int log2 = 0;
1127
1128 for (; n > 1; n >>= 1)
1129 log2++;
1130
1131 return log2;
1132 }
1133
1134 static inline int exp2i(int n)
1135 {
1136 return 1 << n;
1137 }
1138
1139 /*
1140 * Estimate the number of bisect steps left (after the current step)
1141 *
1142 * For any x between 0 included and 2^n excluded, the probability for
1143 * n - 1 steps left looks like:
1144 *
1145 * P(2^n + x) == (2^n - x) / (2^n + x)
1146 *
1147 * and P(2^n + x) < 0.5 means 2^n < 3x
1148 */
1149 int estimate_bisect_steps(int all)
1150 {
1151 int n, x, e;
1152
1153 if (all < 3)
1154 return 0;
1155
1156 n = log2i(all);
1157 e = exp2i(n);
1158 x = all - e;
1159
1160 return (e < 3 * x) ? n : n - 1;
1161 }
1162
1163 static int mark_for_removal(const char *refname,
1164 const struct object_id *oid UNUSED,
1165 int flag UNUSED, void *cb_data)
1166 {
1167 struct string_list *refs = cb_data;
1168 char *ref = xstrfmt("refs/bisect%s", refname);
1169 string_list_append(refs, ref);
1170 return 0;
1171 }
1172
1173 int bisect_clean_state(void)
1174 {
1175 int result = 0;
1176
1177 /* There may be some refs packed during bisection */
1178 struct string_list refs_for_removal = STRING_LIST_INIT_NODUP;
1179 for_each_ref_in("refs/bisect", mark_for_removal, (void *) &refs_for_removal);
1180 string_list_append(&refs_for_removal, xstrdup("BISECT_HEAD"));
1181 result = delete_refs("bisect: remove", &refs_for_removal, REF_NO_DEREF);
1182 refs_for_removal.strdup_strings = 1;
1183 string_list_clear(&refs_for_removal, 0);
1184 unlink_or_warn(git_path_bisect_expected_rev());
1185 unlink_or_warn(git_path_bisect_ancestors_ok());
1186 unlink_or_warn(git_path_bisect_log());
1187 unlink_or_warn(git_path_bisect_names());
1188 unlink_or_warn(git_path_bisect_run());
1189 unlink_or_warn(git_path_bisect_terms());
1190 unlink_or_warn(git_path_bisect_first_parent());
1191 /* Cleanup head-name if it got left by an old version of git-bisect */
1192 unlink_or_warn(git_path_head_name());
1193 /*
1194 * Cleanup BISECT_START last to support the --no-checkout option
1195 * introduced in the commit 4796e823a.
1196 */
1197 unlink_or_warn(git_path_bisect_start());
1198
1199 return result;
1200 }