Merge branch 'tb/complete-describe'
[git/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 "sha1-lookup.h"
10 #include "run-command.h"
11 #include "log-tree.h"
12 #include "bisect.h"
13 #include "sha1-array.h"
14 #include "argv-array.h"
15
16 static struct oid_array good_revs;
17 static struct oid_array skipped_revs;
18
19 static struct object_id *current_bad_oid;
20
21 static const char *argv_checkout[] = {"checkout", "-q", NULL, "--", NULL};
22 static const char *argv_show_branch[] = {"show-branch", NULL, NULL};
23
24 static const char *term_bad;
25 static const char *term_good;
26
27 /* Remember to update object flag allocation in object.h */
28 #define COUNTED (1u<<16)
29
30 /*
31 * This is a truly stupid algorithm, but it's only
32 * used for bisection, and we just don't care enough.
33 *
34 * We care just barely enough to avoid recursing for
35 * non-merge entries.
36 */
37 static int count_distance(struct commit_list *entry)
38 {
39 int nr = 0;
40
41 while (entry) {
42 struct commit *commit = entry->item;
43 struct commit_list *p;
44
45 if (commit->object.flags & (UNINTERESTING | COUNTED))
46 break;
47 if (!(commit->object.flags & TREESAME))
48 nr++;
49 commit->object.flags |= COUNTED;
50 p = commit->parents;
51 entry = p;
52 if (p) {
53 p = p->next;
54 while (p) {
55 nr += count_distance(p);
56 p = p->next;
57 }
58 }
59 }
60
61 return nr;
62 }
63
64 static void clear_distance(struct commit_list *list)
65 {
66 while (list) {
67 struct commit *commit = list->item;
68 commit->object.flags &= ~COUNTED;
69 list = list->next;
70 }
71 }
72
73 #define DEBUG_BISECT 0
74
75 static inline int weight(struct commit_list *elem)
76 {
77 return *((int*)(elem->item->util));
78 }
79
80 static inline void weight_set(struct commit_list *elem, int weight)
81 {
82 *((int*)(elem->item->util)) = weight;
83 }
84
85 static int count_interesting_parents(struct commit *commit)
86 {
87 struct commit_list *p;
88 int count;
89
90 for (count = 0, p = commit->parents; p; p = p->next) {
91 if (p->item->object.flags & UNINTERESTING)
92 continue;
93 count++;
94 }
95 return count;
96 }
97
98 static inline int halfway(struct commit_list *p, int nr)
99 {
100 /*
101 * Don't short-cut something we are not going to return!
102 */
103 if (p->item->object.flags & TREESAME)
104 return 0;
105 if (DEBUG_BISECT)
106 return 0;
107 /*
108 * 2 and 3 are halfway of 5.
109 * 3 is halfway of 6 but 2 and 4 are not.
110 */
111 switch (2 * weight(p) - nr) {
112 case -1: case 0: case 1:
113 return 1;
114 default:
115 return 0;
116 }
117 }
118
119 #if !DEBUG_BISECT
120 #define show_list(a,b,c,d) do { ; } while (0)
121 #else
122 static void show_list(const char *debug, int counted, int nr,
123 struct commit_list *list)
124 {
125 struct commit_list *p;
126
127 fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr);
128
129 for (p = list; p; p = p->next) {
130 struct commit_list *pp;
131 struct commit *commit = p->item;
132 unsigned flags = commit->object.flags;
133 enum object_type type;
134 unsigned long size;
135 char *buf = read_sha1_file(commit->object.sha1, &type, &size);
136 const char *subject_start;
137 int subject_len;
138
139 fprintf(stderr, "%c%c%c ",
140 (flags & TREESAME) ? ' ' : 'T',
141 (flags & UNINTERESTING) ? 'U' : ' ',
142 (flags & COUNTED) ? 'C' : ' ');
143 if (commit->util)
144 fprintf(stderr, "%3d", weight(p));
145 else
146 fprintf(stderr, "---");
147 fprintf(stderr, " %.*s", 8, sha1_to_hex(commit->object.sha1));
148 for (pp = commit->parents; pp; pp = pp->next)
149 fprintf(stderr, " %.*s", 8,
150 sha1_to_hex(pp->item->object.sha1));
151
152 subject_len = find_commit_subject(buf, &subject_start);
153 if (subject_len)
154 fprintf(stderr, " %.*s", subject_len, subject_start);
155 fprintf(stderr, "\n");
156 }
157 }
158 #endif /* DEBUG_BISECT */
159
160 static struct commit_list *best_bisection(struct commit_list *list, int nr)
161 {
162 struct commit_list *p, *best;
163 int best_distance = -1;
164
165 best = list;
166 for (p = list; p; p = p->next) {
167 int distance;
168 unsigned flags = p->item->object.flags;
169
170 if (flags & TREESAME)
171 continue;
172 distance = weight(p);
173 if (nr - distance < distance)
174 distance = nr - distance;
175 if (distance > best_distance) {
176 best = p;
177 best_distance = distance;
178 }
179 }
180
181 return best;
182 }
183
184 struct commit_dist {
185 struct commit *commit;
186 int distance;
187 };
188
189 static int compare_commit_dist(const void *a_, const void *b_)
190 {
191 struct commit_dist *a, *b;
192
193 a = (struct commit_dist *)a_;
194 b = (struct commit_dist *)b_;
195 if (a->distance != b->distance)
196 return b->distance - a->distance; /* desc sort */
197 return oidcmp(&a->commit->object.oid, &b->commit->object.oid);
198 }
199
200 static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
201 {
202 struct commit_list *p;
203 struct commit_dist *array = xcalloc(nr, sizeof(*array));
204 struct strbuf buf = STRBUF_INIT;
205 int cnt, i;
206
207 for (p = list, cnt = 0; p; p = p->next) {
208 int distance;
209 unsigned flags = p->item->object.flags;
210
211 if (flags & TREESAME)
212 continue;
213 distance = weight(p);
214 if (nr - distance < distance)
215 distance = nr - distance;
216 array[cnt].commit = p->item;
217 array[cnt].distance = distance;
218 cnt++;
219 }
220 QSORT(array, cnt, compare_commit_dist);
221 for (p = list, i = 0; i < cnt; i++) {
222 struct object *obj = &(array[i].commit->object);
223
224 strbuf_reset(&buf);
225 strbuf_addf(&buf, "dist=%d", array[i].distance);
226 add_name_decoration(DECORATION_NONE, buf.buf, obj);
227
228 p->item = array[i].commit;
229 p = p->next;
230 }
231 if (p)
232 p->next = NULL;
233 strbuf_release(&buf);
234 free(array);
235 return list;
236 }
237
238 /*
239 * zero or positive weight is the number of interesting commits it can
240 * reach, including itself. Especially, weight = 0 means it does not
241 * reach any tree-changing commits (e.g. just above uninteresting one
242 * but traversal is with pathspec).
243 *
244 * weight = -1 means it has one parent and its distance is yet to
245 * be computed.
246 *
247 * weight = -2 means it has more than one parent and its distance is
248 * unknown. After running count_distance() first, they will get zero
249 * or positive distance.
250 */
251 static struct commit_list *do_find_bisection(struct commit_list *list,
252 int nr, int *weights,
253 int find_all)
254 {
255 int n, counted;
256 struct commit_list *p;
257
258 counted = 0;
259
260 for (n = 0, p = list; p; p = p->next) {
261 struct commit *commit = p->item;
262 unsigned flags = commit->object.flags;
263
264 p->item->util = &weights[n++];
265 switch (count_interesting_parents(commit)) {
266 case 0:
267 if (!(flags & TREESAME)) {
268 weight_set(p, 1);
269 counted++;
270 show_list("bisection 2 count one",
271 counted, nr, list);
272 }
273 /*
274 * otherwise, it is known not to reach any
275 * tree-changing commit and gets weight 0.
276 */
277 break;
278 case 1:
279 weight_set(p, -1);
280 break;
281 default:
282 weight_set(p, -2);
283 break;
284 }
285 }
286
287 show_list("bisection 2 initialize", counted, nr, list);
288
289 /*
290 * If you have only one parent in the resulting set
291 * then you can reach one commit more than that parent
292 * can reach. So we do not have to run the expensive
293 * count_distance() for single strand of pearls.
294 *
295 * However, if you have more than one parents, you cannot
296 * just add their distance and one for yourself, since
297 * they usually reach the same ancestor and you would
298 * end up counting them twice that way.
299 *
300 * So we will first count distance of merges the usual
301 * way, and then fill the blanks using cheaper algorithm.
302 */
303 for (p = list; p; p = p->next) {
304 if (p->item->object.flags & UNINTERESTING)
305 continue;
306 if (weight(p) != -2)
307 continue;
308 weight_set(p, count_distance(p));
309 clear_distance(list);
310
311 /* Does it happen to be at exactly half-way? */
312 if (!find_all && halfway(p, nr))
313 return p;
314 counted++;
315 }
316
317 show_list("bisection 2 count_distance", counted, nr, list);
318
319 while (counted < nr) {
320 for (p = list; p; p = p->next) {
321 struct commit_list *q;
322 unsigned flags = p->item->object.flags;
323
324 if (0 <= weight(p))
325 continue;
326 for (q = p->item->parents; q; q = q->next) {
327 if (q->item->object.flags & UNINTERESTING)
328 continue;
329 if (0 <= weight(q))
330 break;
331 }
332 if (!q)
333 continue;
334
335 /*
336 * weight for p is unknown but q is known.
337 * add one for p itself if p is to be counted,
338 * otherwise inherit it from q directly.
339 */
340 if (!(flags & TREESAME)) {
341 weight_set(p, weight(q)+1);
342 counted++;
343 show_list("bisection 2 count one",
344 counted, nr, list);
345 }
346 else
347 weight_set(p, weight(q));
348
349 /* Does it happen to be at exactly half-way? */
350 if (!find_all && halfway(p, nr))
351 return p;
352 }
353 }
354
355 show_list("bisection 2 counted all", counted, nr, list);
356
357 if (!find_all)
358 return best_bisection(list, nr);
359 else
360 return best_bisection_sorted(list, nr);
361 }
362
363 struct commit_list *find_bisection(struct commit_list *list,
364 int *reaches, int *all,
365 int find_all)
366 {
367 int nr, on_list;
368 struct commit_list *p, *best, *next, *last;
369 int *weights;
370
371 show_list("bisection 2 entry", 0, 0, list);
372
373 /*
374 * Count the number of total and tree-changing items on the
375 * list, while reversing the list.
376 */
377 for (nr = on_list = 0, last = NULL, p = list;
378 p;
379 p = next) {
380 unsigned flags = p->item->object.flags;
381
382 next = p->next;
383 if (flags & UNINTERESTING)
384 continue;
385 p->next = last;
386 last = p;
387 if (!(flags & TREESAME))
388 nr++;
389 on_list++;
390 }
391 list = last;
392 show_list("bisection 2 sorted", 0, nr, list);
393
394 *all = nr;
395 weights = xcalloc(on_list, sizeof(*weights));
396
397 /* Do the real work of finding bisection commit. */
398 best = do_find_bisection(list, nr, weights, find_all);
399 if (best) {
400 if (!find_all)
401 best->next = NULL;
402 *reaches = weight(best);
403 }
404 free(weights);
405 return best;
406 }
407
408 static int register_ref(const char *refname, const struct object_id *oid,
409 int flags, void *cb_data)
410 {
411 struct strbuf good_prefix = STRBUF_INIT;
412 strbuf_addstr(&good_prefix, term_good);
413 strbuf_addstr(&good_prefix, "-");
414
415 if (!strcmp(refname, term_bad)) {
416 current_bad_oid = xmalloc(sizeof(*current_bad_oid));
417 oidcpy(current_bad_oid, oid);
418 } else if (starts_with(refname, good_prefix.buf)) {
419 oid_array_append(&good_revs, oid);
420 } else if (starts_with(refname, "skip-")) {
421 oid_array_append(&skipped_revs, oid);
422 }
423
424 strbuf_release(&good_prefix);
425
426 return 0;
427 }
428
429 static int read_bisect_refs(void)
430 {
431 return for_each_ref_in("refs/bisect/", register_ref, NULL);
432 }
433
434 static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
435 static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")
436 static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
437
438 static void read_bisect_paths(struct argv_array *array)
439 {
440 struct strbuf str = STRBUF_INIT;
441 const char *filename = git_path_bisect_names();
442 FILE *fp = xfopen(filename, "r");
443
444 while (strbuf_getline_lf(&str, fp) != EOF) {
445 strbuf_trim(&str);
446 if (sq_dequote_to_argv_array(str.buf, array))
447 die(_("Badly quoted content in file '%s': %s"),
448 filename, str.buf);
449 }
450
451 strbuf_release(&str);
452 fclose(fp);
453 }
454
455 static char *join_sha1_array_hex(struct oid_array *array, char delim)
456 {
457 struct strbuf joined_hexs = STRBUF_INIT;
458 int i;
459
460 for (i = 0; i < array->nr; i++) {
461 strbuf_addstr(&joined_hexs, oid_to_hex(array->oid + i));
462 if (i + 1 < array->nr)
463 strbuf_addch(&joined_hexs, delim);
464 }
465
466 return strbuf_detach(&joined_hexs, NULL);
467 }
468
469 /*
470 * In this function, passing a not NULL skipped_first is very special.
471 * It means that we want to know if the first commit in the list is
472 * skipped because we will want to test a commit away from it if it is
473 * indeed skipped.
474 * So if the first commit is skipped, we cannot take the shortcut to
475 * just "return list" when we find the first non skipped commit, we
476 * have to return a fully filtered list.
477 *
478 * We use (*skipped_first == -1) to mean "it has been found that the
479 * first commit is not skipped". In this case *skipped_first is set back
480 * to 0 just before the function returns.
481 */
482 struct commit_list *filter_skipped(struct commit_list *list,
483 struct commit_list **tried,
484 int show_all,
485 int *count,
486 int *skipped_first)
487 {
488 struct commit_list *filtered = NULL, **f = &filtered;
489
490 *tried = NULL;
491
492 if (skipped_first)
493 *skipped_first = 0;
494 if (count)
495 *count = 0;
496
497 if (!skipped_revs.nr)
498 return list;
499
500 while (list) {
501 struct commit_list *next = list->next;
502 list->next = NULL;
503 if (0 <= oid_array_lookup(&skipped_revs, &list->item->object.oid)) {
504 if (skipped_first && !*skipped_first)
505 *skipped_first = 1;
506 /* Move current to tried list */
507 *tried = list;
508 tried = &list->next;
509 } else {
510 if (!show_all) {
511 if (!skipped_first || !*skipped_first)
512 return list;
513 } else if (skipped_first && !*skipped_first) {
514 /* This means we know it's not skipped */
515 *skipped_first = -1;
516 }
517 /* Move current to filtered list */
518 *f = list;
519 f = &list->next;
520 if (count)
521 (*count)++;
522 }
523 list = next;
524 }
525
526 if (skipped_first && *skipped_first == -1)
527 *skipped_first = 0;
528
529 return filtered;
530 }
531
532 #define PRN_MODULO 32768
533
534 /*
535 * This is a pseudo random number generator based on "man 3 rand".
536 * It is not used properly because the seed is the argument and it
537 * is increased by one between each call, but that should not matter
538 * for this application.
539 */
540 static unsigned get_prn(unsigned count) {
541 count = count * 1103515245 + 12345;
542 return (count/65536) % PRN_MODULO;
543 }
544
545 /*
546 * Custom integer square root from
547 * https://en.wikipedia.org/wiki/Integer_square_root
548 */
549 static int sqrti(int val)
550 {
551 float d, x = val;
552
553 if (val == 0)
554 return 0;
555
556 do {
557 float y = (x + (float)val / x) / 2;
558 d = (y > x) ? y - x : x - y;
559 x = y;
560 } while (d >= 0.5);
561
562 return (int)x;
563 }
564
565 static struct commit_list *skip_away(struct commit_list *list, int count)
566 {
567 struct commit_list *cur, *previous;
568 int prn, index, i;
569
570 prn = get_prn(count);
571 index = (count * prn / PRN_MODULO) * sqrti(prn) / sqrti(PRN_MODULO);
572
573 cur = list;
574 previous = NULL;
575
576 for (i = 0; cur; cur = cur->next, i++) {
577 if (i == index) {
578 if (oidcmp(&cur->item->object.oid, current_bad_oid))
579 return cur;
580 if (previous)
581 return previous;
582 return list;
583 }
584 previous = cur;
585 }
586
587 return list;
588 }
589
590 static struct commit_list *managed_skipped(struct commit_list *list,
591 struct commit_list **tried)
592 {
593 int count, skipped_first;
594
595 *tried = NULL;
596
597 if (!skipped_revs.nr)
598 return list;
599
600 list = filter_skipped(list, tried, 0, &count, &skipped_first);
601
602 if (!skipped_first)
603 return list;
604
605 return skip_away(list, count);
606 }
607
608 static void bisect_rev_setup(struct rev_info *revs, const char *prefix,
609 const char *bad_format, const char *good_format,
610 int read_paths)
611 {
612 struct argv_array rev_argv = ARGV_ARRAY_INIT;
613 int i;
614
615 init_revisions(revs, prefix);
616 revs->abbrev = 0;
617 revs->commit_format = CMIT_FMT_UNSPECIFIED;
618
619 /* rev_argv.argv[0] will be ignored by setup_revisions */
620 argv_array_push(&rev_argv, "bisect_rev_setup");
621 argv_array_pushf(&rev_argv, bad_format, oid_to_hex(current_bad_oid));
622 for (i = 0; i < good_revs.nr; i++)
623 argv_array_pushf(&rev_argv, good_format,
624 oid_to_hex(good_revs.oid + i));
625 argv_array_push(&rev_argv, "--");
626 if (read_paths)
627 read_bisect_paths(&rev_argv);
628
629 setup_revisions(rev_argv.argc, rev_argv.argv, revs, NULL);
630 /* XXX leak rev_argv, as "revs" may still be pointing to it */
631 }
632
633 static void bisect_common(struct rev_info *revs)
634 {
635 if (prepare_revision_walk(revs))
636 die("revision walk setup failed");
637 if (revs->tree_objects)
638 mark_edges_uninteresting(revs, NULL);
639 }
640
641 static void exit_if_skipped_commits(struct commit_list *tried,
642 const struct object_id *bad)
643 {
644 if (!tried)
645 return;
646
647 printf("There are only 'skip'ped commits left to test.\n"
648 "The first %s commit could be any of:\n", term_bad);
649
650 for ( ; tried; tried = tried->next)
651 printf("%s\n", oid_to_hex(&tried->item->object.oid));
652
653 if (bad)
654 printf("%s\n", oid_to_hex(bad));
655 printf(_("We cannot bisect more!\n"));
656 exit(2);
657 }
658
659 static int is_expected_rev(const struct object_id *oid)
660 {
661 const char *filename = git_path_bisect_expected_rev();
662 struct stat st;
663 struct strbuf str = STRBUF_INIT;
664 FILE *fp;
665 int res = 0;
666
667 if (stat(filename, &st) || !S_ISREG(st.st_mode))
668 return 0;
669
670 fp = fopen_or_warn(filename, "r");
671 if (!fp)
672 return 0;
673
674 if (strbuf_getline_lf(&str, fp) != EOF)
675 res = !strcmp(str.buf, oid_to_hex(oid));
676
677 strbuf_release(&str);
678 fclose(fp);
679
680 return res;
681 }
682
683 static int bisect_checkout(const struct object_id *bisect_rev, int no_checkout)
684 {
685 char bisect_rev_hex[GIT_MAX_HEXSZ + 1];
686
687 memcpy(bisect_rev_hex, oid_to_hex(bisect_rev), GIT_SHA1_HEXSZ + 1);
688 update_ref(NULL, "BISECT_EXPECTED_REV", bisect_rev->hash, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
689
690 argv_checkout[2] = bisect_rev_hex;
691 if (no_checkout) {
692 update_ref(NULL, "BISECT_HEAD", bisect_rev->hash, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
693 } else {
694 int res;
695 res = run_command_v_opt(argv_checkout, RUN_GIT_CMD);
696 if (res)
697 exit(res);
698 }
699
700 argv_show_branch[1] = bisect_rev_hex;
701 return run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
702 }
703
704 static struct commit *get_commit_reference(const struct object_id *oid)
705 {
706 struct commit *r = lookup_commit_reference(oid);
707 if (!r)
708 die(_("Not a valid commit name %s"), oid_to_hex(oid));
709 return r;
710 }
711
712 static struct commit **get_bad_and_good_commits(int *rev_nr)
713 {
714 struct commit **rev;
715 int i, n = 0;
716
717 ALLOC_ARRAY(rev, 1 + good_revs.nr);
718 rev[n++] = get_commit_reference(current_bad_oid);
719 for (i = 0; i < good_revs.nr; i++)
720 rev[n++] = get_commit_reference(good_revs.oid + i);
721 *rev_nr = n;
722
723 return rev;
724 }
725
726 static void handle_bad_merge_base(void)
727 {
728 if (is_expected_rev(current_bad_oid)) {
729 char *bad_hex = oid_to_hex(current_bad_oid);
730 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
731 if (!strcmp(term_bad, "bad") && !strcmp(term_good, "good")) {
732 fprintf(stderr, _("The merge base %s is bad.\n"
733 "This means the bug has been fixed "
734 "between %s and [%s].\n"),
735 bad_hex, bad_hex, good_hex);
736 } else if (!strcmp(term_bad, "new") && !strcmp(term_good, "old")) {
737 fprintf(stderr, _("The merge base %s is new.\n"
738 "The property has changed "
739 "between %s and [%s].\n"),
740 bad_hex, bad_hex, good_hex);
741 } else {
742 fprintf(stderr, _("The merge base %s is %s.\n"
743 "This means the first '%s' commit is "
744 "between %s and [%s].\n"),
745 bad_hex, term_bad, term_good, bad_hex, good_hex);
746 }
747 exit(3);
748 }
749
750 fprintf(stderr, _("Some %s revs are not ancestors of the %s rev.\n"
751 "git bisect cannot work properly in this case.\n"
752 "Maybe you mistook %s and %s revs?\n"),
753 term_good, term_bad, term_good, term_bad);
754 exit(1);
755 }
756
757 static void handle_skipped_merge_base(const struct object_id *mb)
758 {
759 char *mb_hex = oid_to_hex(mb);
760 char *bad_hex = oid_to_hex(current_bad_oid);
761 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
762
763 warning(_("the merge base between %s and [%s] "
764 "must be skipped.\n"
765 "So we cannot be sure the first %s commit is "
766 "between %s and %s.\n"
767 "We continue anyway."),
768 bad_hex, good_hex, term_bad, mb_hex, bad_hex);
769 free(good_hex);
770 }
771
772 /*
773 * "check_merge_bases" checks that merge bases are not "bad" (or "new").
774 *
775 * - If one is "bad" (or "new"), it means the user assumed something wrong
776 * and we must exit with a non 0 error code.
777 * - If one is "good" (or "old"), that's good, we have nothing to do.
778 * - If one is "skipped", we can't know but we should warn.
779 * - If we don't know, we should check it out and ask the user to test.
780 */
781 static void check_merge_bases(int no_checkout)
782 {
783 struct commit_list *result;
784 int rev_nr;
785 struct commit **rev = get_bad_and_good_commits(&rev_nr);
786
787 result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1);
788
789 for (; result; result = result->next) {
790 const struct object_id *mb = &result->item->object.oid;
791 if (!oidcmp(mb, current_bad_oid)) {
792 handle_bad_merge_base();
793 } else if (0 <= oid_array_lookup(&good_revs, mb)) {
794 continue;
795 } else if (0 <= oid_array_lookup(&skipped_revs, mb)) {
796 handle_skipped_merge_base(mb);
797 } else {
798 printf(_("Bisecting: a merge base must be tested\n"));
799 exit(bisect_checkout(mb, no_checkout));
800 }
801 }
802
803 free(rev);
804 free_commit_list(result);
805 }
806
807 static int check_ancestors(const char *prefix)
808 {
809 struct rev_info revs;
810 struct object_array pending_copy;
811 int res;
812
813 bisect_rev_setup(&revs, prefix, "^%s", "%s", 0);
814
815 /* Save pending objects, so they can be cleaned up later. */
816 pending_copy = revs.pending;
817 revs.leak_pending = 1;
818
819 /*
820 * bisect_common calls prepare_revision_walk right away, which
821 * (together with .leak_pending = 1) makes us the sole owner of
822 * the list of pending objects.
823 */
824 bisect_common(&revs);
825 res = (revs.commits != NULL);
826
827 /* Clean up objects used, as they will be reused. */
828 clear_commit_marks_for_object_array(&pending_copy, ALL_REV_FLAGS);
829
830 object_array_clear(&pending_copy);
831
832 return res;
833 }
834
835 /*
836 * "check_good_are_ancestors_of_bad" checks that all "good" revs are
837 * ancestor of the "bad" rev.
838 *
839 * If that's not the case, we need to check the merge bases.
840 * If a merge base must be tested by the user, its source code will be
841 * checked out to be tested by the user and we will exit.
842 */
843 static void check_good_are_ancestors_of_bad(const char *prefix, int no_checkout)
844 {
845 char *filename = git_pathdup("BISECT_ANCESTORS_OK");
846 struct stat st;
847 int fd;
848
849 if (!current_bad_oid)
850 die(_("a %s revision is needed"), term_bad);
851
852 /* Check if file BISECT_ANCESTORS_OK exists. */
853 if (!stat(filename, &st) && S_ISREG(st.st_mode))
854 goto done;
855
856 /* Bisecting with no good rev is ok. */
857 if (good_revs.nr == 0)
858 goto done;
859
860 /* Check if all good revs are ancestor of the bad rev. */
861 if (check_ancestors(prefix))
862 check_merge_bases(no_checkout);
863
864 /* Create file BISECT_ANCESTORS_OK. */
865 fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
866 if (fd < 0)
867 warning_errno(_("could not create file '%s'"),
868 filename);
869 else
870 close(fd);
871 done:
872 free(filename);
873 }
874
875 /*
876 * This does "git diff-tree --pretty COMMIT" without one fork+exec.
877 */
878 static void show_diff_tree(const char *prefix, struct commit *commit)
879 {
880 struct rev_info opt;
881
882 /* diff-tree init */
883 init_revisions(&opt, prefix);
884 git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
885 opt.abbrev = 0;
886 opt.diff = 1;
887
888 /* This is what "--pretty" does */
889 opt.verbose_header = 1;
890 opt.use_terminator = 0;
891 opt.commit_format = CMIT_FMT_DEFAULT;
892
893 /* diff-tree init */
894 if (!opt.diffopt.output_format)
895 opt.diffopt.output_format = DIFF_FORMAT_RAW;
896
897 setup_revisions(0, NULL, &opt, NULL);
898 log_tree_commit(&opt, commit);
899 }
900
901 /*
902 * The terms used for this bisect session are stored in BISECT_TERMS.
903 * We read them and store them to adapt the messages accordingly.
904 * Default is bad/good.
905 */
906 void read_bisect_terms(const char **read_bad, const char **read_good)
907 {
908 struct strbuf str = STRBUF_INIT;
909 const char *filename = git_path_bisect_terms();
910 FILE *fp = fopen(filename, "r");
911
912 if (!fp) {
913 if (errno == ENOENT) {
914 *read_bad = "bad";
915 *read_good = "good";
916 return;
917 } else {
918 die_errno(_("could not read file '%s'"), filename);
919 }
920 } else {
921 strbuf_getline_lf(&str, fp);
922 *read_bad = strbuf_detach(&str, NULL);
923 strbuf_getline_lf(&str, fp);
924 *read_good = strbuf_detach(&str, NULL);
925 }
926 strbuf_release(&str);
927 fclose(fp);
928 }
929
930 /*
931 * We use the convention that exiting with an exit code 10 means that
932 * the bisection process finished successfully.
933 * In this case the calling shell script should exit 0.
934 *
935 * If no_checkout is non-zero, the bisection process does not
936 * checkout the trial commit but instead simply updates BISECT_HEAD.
937 */
938 int bisect_next_all(const char *prefix, int no_checkout)
939 {
940 struct rev_info revs;
941 struct commit_list *tried;
942 int reaches = 0, all = 0, nr, steps;
943 struct object_id *bisect_rev;
944 char *steps_msg;
945
946 read_bisect_terms(&term_bad, &term_good);
947 if (read_bisect_refs())
948 die(_("reading bisect refs failed"));
949
950 check_good_are_ancestors_of_bad(prefix, no_checkout);
951
952 bisect_rev_setup(&revs, prefix, "%s", "^%s", 1);
953 revs.limited = 1;
954
955 bisect_common(&revs);
956
957 revs.commits = find_bisection(revs.commits, &reaches, &all,
958 !!skipped_revs.nr);
959 revs.commits = managed_skipped(revs.commits, &tried);
960
961 if (!revs.commits) {
962 /*
963 * We should exit here only if the "bad"
964 * commit is also a "skip" commit.
965 */
966 exit_if_skipped_commits(tried, NULL);
967
968 printf(_("%s was both %s and %s\n"),
969 oid_to_hex(current_bad_oid),
970 term_good,
971 term_bad);
972 exit(1);
973 }
974
975 if (!all) {
976 fprintf(stderr, _("No testable commit found.\n"
977 "Maybe you started with bad path parameters?\n"));
978 exit(4);
979 }
980
981 bisect_rev = &revs.commits->item->object.oid;
982
983 if (!oidcmp(bisect_rev, current_bad_oid)) {
984 exit_if_skipped_commits(tried, current_bad_oid);
985 printf("%s is the first %s commit\n", oid_to_hex(bisect_rev),
986 term_bad);
987 show_diff_tree(prefix, revs.commits->item);
988 /* This means the bisection process succeeded. */
989 exit(10);
990 }
991
992 nr = all - reaches - 1;
993 steps = estimate_bisect_steps(all);
994
995 steps_msg = xstrfmt(Q_("(roughly %d step)", "(roughly %d steps)",
996 steps), steps);
997 /*
998 * TRANSLATORS: the last %s will be replaced with "(roughly %d
999 * steps)" translation.
1000 */
1001 printf(Q_("Bisecting: %d revision left to test after this %s\n",
1002 "Bisecting: %d revisions left to test after this %s\n",
1003 nr), nr, steps_msg);
1004 free(steps_msg);
1005
1006 return bisect_checkout(bisect_rev, no_checkout);
1007 }
1008
1009 static inline int log2i(int n)
1010 {
1011 int log2 = 0;
1012
1013 for (; n > 1; n >>= 1)
1014 log2++;
1015
1016 return log2;
1017 }
1018
1019 static inline int exp2i(int n)
1020 {
1021 return 1 << n;
1022 }
1023
1024 /*
1025 * Estimate the number of bisect steps left (after the current step)
1026 *
1027 * For any x between 0 included and 2^n excluded, the probability for
1028 * n - 1 steps left looks like:
1029 *
1030 * P(2^n + x) == (2^n - x) / (2^n + x)
1031 *
1032 * and P(2^n + x) < 0.5 means 2^n < 3x
1033 */
1034 int estimate_bisect_steps(int all)
1035 {
1036 int n, x, e;
1037
1038 if (all < 3)
1039 return 0;
1040
1041 n = log2i(all);
1042 e = exp2i(n);
1043 x = all - e;
1044
1045 return (e < 3 * x) ? n : n - 1;
1046 }