Merge branch 'ab/push-cas-doc-n-test'
[git/git.git] / bisect.c
1 #include "cache.h"
2 #include "commit.h"
3 #include "diff.h"
4 #include "revision.h"
5 #include "refs.h"
6 #include "list-objects.h"
7 #include "quote.h"
8 #include "sha1-lookup.h"
9 #include "run-command.h"
10 #include "log-tree.h"
11 #include "bisect.h"
12 #include "sha1-array.h"
13 #include "argv-array.h"
14
15 static struct oid_array good_revs;
16 static struct oid_array skipped_revs;
17
18 static struct object_id *current_bad_oid;
19
20 static const char *argv_checkout[] = {"checkout", "-q", NULL, "--", NULL};
21 static const char *argv_show_branch[] = {"show-branch", NULL, NULL};
22
23 static const char *term_bad;
24 static const char *term_good;
25
26 /* Remember to update object flag allocation in object.h */
27 #define COUNTED (1u<<16)
28
29 /*
30 * This is a truly stupid algorithm, but it's only
31 * used for bisection, and we just don't care enough.
32 *
33 * We care just barely enough to avoid recursing for
34 * non-merge entries.
35 */
36 static int count_distance(struct commit_list *entry)
37 {
38 int nr = 0;
39
40 while (entry) {
41 struct commit *commit = entry->item;
42 struct commit_list *p;
43
44 if (commit->object.flags & (UNINTERESTING | COUNTED))
45 break;
46 if (!(commit->object.flags & TREESAME))
47 nr++;
48 commit->object.flags |= COUNTED;
49 p = commit->parents;
50 entry = p;
51 if (p) {
52 p = p->next;
53 while (p) {
54 nr += count_distance(p);
55 p = p->next;
56 }
57 }
58 }
59
60 return nr;
61 }
62
63 static void clear_distance(struct commit_list *list)
64 {
65 while (list) {
66 struct commit *commit = list->item;
67 commit->object.flags &= ~COUNTED;
68 list = list->next;
69 }
70 }
71
72 #define DEBUG_BISECT 0
73
74 static inline int weight(struct commit_list *elem)
75 {
76 return *((int*)(elem->item->util));
77 }
78
79 static inline void weight_set(struct commit_list *elem, int weight)
80 {
81 *((int*)(elem->item->util)) = weight;
82 }
83
84 static int count_interesting_parents(struct commit *commit)
85 {
86 struct commit_list *p;
87 int count;
88
89 for (count = 0, p = commit->parents; p; p = p->next) {
90 if (p->item->object.flags & UNINTERESTING)
91 continue;
92 count++;
93 }
94 return count;
95 }
96
97 static inline int halfway(struct commit_list *p, int nr)
98 {
99 /*
100 * Don't short-cut something we are not going to return!
101 */
102 if (p->item->object.flags & TREESAME)
103 return 0;
104 if (DEBUG_BISECT)
105 return 0;
106 /*
107 * 2 and 3 are halfway of 5.
108 * 3 is halfway of 6 but 2 and 4 are not.
109 */
110 switch (2 * weight(p) - nr) {
111 case -1: case 0: case 1:
112 return 1;
113 default:
114 return 0;
115 }
116 }
117
118 #if !DEBUG_BISECT
119 #define show_list(a,b,c,d) do { ; } while (0)
120 #else
121 static void show_list(const char *debug, int counted, int nr,
122 struct commit_list *list)
123 {
124 struct commit_list *p;
125
126 fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr);
127
128 for (p = list; p; p = p->next) {
129 struct commit_list *pp;
130 struct commit *commit = p->item;
131 unsigned flags = commit->object.flags;
132 enum object_type type;
133 unsigned long size;
134 char *buf = read_sha1_file(commit->object.sha1, &type, &size);
135 const char *subject_start;
136 int subject_len;
137
138 fprintf(stderr, "%c%c%c ",
139 (flags & TREESAME) ? ' ' : 'T',
140 (flags & UNINTERESTING) ? 'U' : ' ',
141 (flags & COUNTED) ? 'C' : ' ');
142 if (commit->util)
143 fprintf(stderr, "%3d", weight(p));
144 else
145 fprintf(stderr, "---");
146 fprintf(stderr, " %.*s", 8, sha1_to_hex(commit->object.sha1));
147 for (pp = commit->parents; pp; pp = pp->next)
148 fprintf(stderr, " %.*s", 8,
149 sha1_to_hex(pp->item->object.sha1));
150
151 subject_len = find_commit_subject(buf, &subject_start);
152 if (subject_len)
153 fprintf(stderr, " %.*s", subject_len, subject_start);
154 fprintf(stderr, "\n");
155 }
156 }
157 #endif /* DEBUG_BISECT */
158
159 static struct commit_list *best_bisection(struct commit_list *list, int nr)
160 {
161 struct commit_list *p, *best;
162 int best_distance = -1;
163
164 best = list;
165 for (p = list; p; p = p->next) {
166 int distance;
167 unsigned flags = p->item->object.flags;
168
169 if (flags & TREESAME)
170 continue;
171 distance = weight(p);
172 if (nr - distance < distance)
173 distance = nr - distance;
174 if (distance > best_distance) {
175 best = p;
176 best_distance = distance;
177 }
178 }
179
180 return best;
181 }
182
183 struct commit_dist {
184 struct commit *commit;
185 int distance;
186 };
187
188 static int compare_commit_dist(const void *a_, const void *b_)
189 {
190 struct commit_dist *a, *b;
191
192 a = (struct commit_dist *)a_;
193 b = (struct commit_dist *)b_;
194 if (a->distance != b->distance)
195 return b->distance - a->distance; /* desc sort */
196 return oidcmp(&a->commit->object.oid, &b->commit->object.oid);
197 }
198
199 static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
200 {
201 struct commit_list *p;
202 struct commit_dist *array = xcalloc(nr, sizeof(*array));
203 struct strbuf buf = STRBUF_INIT;
204 int cnt, i;
205
206 for (p = list, cnt = 0; p; p = p->next) {
207 int distance;
208 unsigned flags = p->item->object.flags;
209
210 if (flags & TREESAME)
211 continue;
212 distance = weight(p);
213 if (nr - distance < distance)
214 distance = nr - distance;
215 array[cnt].commit = p->item;
216 array[cnt].distance = distance;
217 cnt++;
218 }
219 QSORT(array, cnt, compare_commit_dist);
220 for (p = list, i = 0; i < cnt; i++) {
221 struct object *obj = &(array[i].commit->object);
222
223 strbuf_reset(&buf);
224 strbuf_addf(&buf, "dist=%d", array[i].distance);
225 add_name_decoration(DECORATION_NONE, buf.buf, obj);
226
227 p->item = array[i].commit;
228 p = p->next;
229 }
230 if (p)
231 p->next = NULL;
232 strbuf_release(&buf);
233 free(array);
234 return list;
235 }
236
237 /*
238 * zero or positive weight is the number of interesting commits it can
239 * reach, including itself. Especially, weight = 0 means it does not
240 * reach any tree-changing commits (e.g. just above uninteresting one
241 * but traversal is with pathspec).
242 *
243 * weight = -1 means it has one parent and its distance is yet to
244 * be computed.
245 *
246 * weight = -2 means it has more than one parent and its distance is
247 * unknown. After running count_distance() first, they will get zero
248 * or positive distance.
249 */
250 static struct commit_list *do_find_bisection(struct commit_list *list,
251 int nr, int *weights,
252 int find_all)
253 {
254 int n, counted;
255 struct commit_list *p;
256
257 counted = 0;
258
259 for (n = 0, p = list; p; p = p->next) {
260 struct commit *commit = p->item;
261 unsigned flags = commit->object.flags;
262
263 p->item->util = &weights[n++];
264 switch (count_interesting_parents(commit)) {
265 case 0:
266 if (!(flags & TREESAME)) {
267 weight_set(p, 1);
268 counted++;
269 show_list("bisection 2 count one",
270 counted, nr, list);
271 }
272 /*
273 * otherwise, it is known not to reach any
274 * tree-changing commit and gets weight 0.
275 */
276 break;
277 case 1:
278 weight_set(p, -1);
279 break;
280 default:
281 weight_set(p, -2);
282 break;
283 }
284 }
285
286 show_list("bisection 2 initialize", counted, nr, list);
287
288 /*
289 * If you have only one parent in the resulting set
290 * then you can reach one commit more than that parent
291 * can reach. So we do not have to run the expensive
292 * count_distance() for single strand of pearls.
293 *
294 * However, if you have more than one parents, you cannot
295 * just add their distance and one for yourself, since
296 * they usually reach the same ancestor and you would
297 * end up counting them twice that way.
298 *
299 * So we will first count distance of merges the usual
300 * way, and then fill the blanks using cheaper algorithm.
301 */
302 for (p = list; p; p = p->next) {
303 if (p->item->object.flags & UNINTERESTING)
304 continue;
305 if (weight(p) != -2)
306 continue;
307 weight_set(p, count_distance(p));
308 clear_distance(list);
309
310 /* Does it happen to be at exactly half-way? */
311 if (!find_all && halfway(p, nr))
312 return p;
313 counted++;
314 }
315
316 show_list("bisection 2 count_distance", counted, nr, list);
317
318 while (counted < nr) {
319 for (p = list; p; p = p->next) {
320 struct commit_list *q;
321 unsigned flags = p->item->object.flags;
322
323 if (0 <= weight(p))
324 continue;
325 for (q = p->item->parents; q; q = q->next) {
326 if (q->item->object.flags & UNINTERESTING)
327 continue;
328 if (0 <= weight(q))
329 break;
330 }
331 if (!q)
332 continue;
333
334 /*
335 * weight for p is unknown but q is known.
336 * add one for p itself if p is to be counted,
337 * otherwise inherit it from q directly.
338 */
339 if (!(flags & TREESAME)) {
340 weight_set(p, weight(q)+1);
341 counted++;
342 show_list("bisection 2 count one",
343 counted, nr, list);
344 }
345 else
346 weight_set(p, weight(q));
347
348 /* Does it happen to be at exactly half-way? */
349 if (!find_all && halfway(p, nr))
350 return p;
351 }
352 }
353
354 show_list("bisection 2 counted all", counted, nr, list);
355
356 if (!find_all)
357 return best_bisection(list, nr);
358 else
359 return best_bisection_sorted(list, nr);
360 }
361
362 struct commit_list *find_bisection(struct commit_list *list,
363 int *reaches, int *all,
364 int find_all)
365 {
366 int nr, on_list;
367 struct commit_list *p, *best, *next, *last;
368 int *weights;
369
370 show_list("bisection 2 entry", 0, 0, list);
371
372 /*
373 * Count the number of total and tree-changing items on the
374 * list, while reversing the list.
375 */
376 for (nr = on_list = 0, last = NULL, p = list;
377 p;
378 p = next) {
379 unsigned flags = p->item->object.flags;
380
381 next = p->next;
382 if (flags & UNINTERESTING)
383 continue;
384 p->next = last;
385 last = p;
386 if (!(flags & TREESAME))
387 nr++;
388 on_list++;
389 }
390 list = last;
391 show_list("bisection 2 sorted", 0, nr, list);
392
393 *all = nr;
394 weights = xcalloc(on_list, sizeof(*weights));
395
396 /* Do the real work of finding bisection commit. */
397 best = do_find_bisection(list, nr, weights, find_all);
398 if (best) {
399 if (!find_all)
400 best->next = NULL;
401 *reaches = weight(best);
402 }
403 free(weights);
404 return best;
405 }
406
407 static int register_ref(const char *refname, const struct object_id *oid,
408 int flags, void *cb_data)
409 {
410 struct strbuf good_prefix = STRBUF_INIT;
411 strbuf_addstr(&good_prefix, term_good);
412 strbuf_addstr(&good_prefix, "-");
413
414 if (!strcmp(refname, term_bad)) {
415 current_bad_oid = xmalloc(sizeof(*current_bad_oid));
416 oidcpy(current_bad_oid, oid);
417 } else if (starts_with(refname, good_prefix.buf)) {
418 oid_array_append(&good_revs, oid);
419 } else if (starts_with(refname, "skip-")) {
420 oid_array_append(&skipped_revs, oid);
421 }
422
423 strbuf_release(&good_prefix);
424
425 return 0;
426 }
427
428 static int read_bisect_refs(void)
429 {
430 return for_each_ref_in("refs/bisect/", register_ref, NULL);
431 }
432
433 static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
434 static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")
435
436 static void read_bisect_paths(struct argv_array *array)
437 {
438 struct strbuf str = STRBUF_INIT;
439 const char *filename = git_path_bisect_names();
440 FILE *fp = fopen(filename, "r");
441
442 if (!fp)
443 die_errno(_("Could not open file '%s'"), filename);
444
445 while (strbuf_getline_lf(&str, fp) != EOF) {
446 strbuf_trim(&str);
447 if (sq_dequote_to_argv_array(str.buf, array))
448 die(_("Badly quoted content in file '%s': %s"),
449 filename, str.buf);
450 }
451
452 strbuf_release(&str);
453 fclose(fp);
454 }
455
456 static char *join_sha1_array_hex(struct oid_array *array, char delim)
457 {
458 struct strbuf joined_hexs = STRBUF_INIT;
459 int i;
460
461 for (i = 0; i < array->nr; i++) {
462 strbuf_addstr(&joined_hexs, oid_to_hex(array->oid + i));
463 if (i + 1 < array->nr)
464 strbuf_addch(&joined_hexs, delim);
465 }
466
467 return strbuf_detach(&joined_hexs, NULL);
468 }
469
470 /*
471 * In this function, passing a not NULL skipped_first is very special.
472 * It means that we want to know if the first commit in the list is
473 * skipped because we will want to test a commit away from it if it is
474 * indeed skipped.
475 * So if the first commit is skipped, we cannot take the shortcut to
476 * just "return list" when we find the first non skipped commit, we
477 * have to return a fully filtered list.
478 *
479 * We use (*skipped_first == -1) to mean "it has been found that the
480 * first commit is not skipped". In this case *skipped_first is set back
481 * to 0 just before the function returns.
482 */
483 struct commit_list *filter_skipped(struct commit_list *list,
484 struct commit_list **tried,
485 int show_all,
486 int *count,
487 int *skipped_first)
488 {
489 struct commit_list *filtered = NULL, **f = &filtered;
490
491 *tried = NULL;
492
493 if (skipped_first)
494 *skipped_first = 0;
495 if (count)
496 *count = 0;
497
498 if (!skipped_revs.nr)
499 return list;
500
501 while (list) {
502 struct commit_list *next = list->next;
503 list->next = NULL;
504 if (0 <= oid_array_lookup(&skipped_revs, &list->item->object.oid)) {
505 if (skipped_first && !*skipped_first)
506 *skipped_first = 1;
507 /* Move current to tried list */
508 *tried = list;
509 tried = &list->next;
510 } else {
511 if (!show_all) {
512 if (!skipped_first || !*skipped_first)
513 return list;
514 } else if (skipped_first && !*skipped_first) {
515 /* This means we know it's not skipped */
516 *skipped_first = -1;
517 }
518 /* Move current to filtered list */
519 *f = list;
520 f = &list->next;
521 if (count)
522 (*count)++;
523 }
524 list = next;
525 }
526
527 if (skipped_first && *skipped_first == -1)
528 *skipped_first = 0;
529
530 return filtered;
531 }
532
533 #define PRN_MODULO 32768
534
535 /*
536 * This is a pseudo random number generator based on "man 3 rand".
537 * It is not used properly because the seed is the argument and it
538 * is increased by one between each call, but that should not matter
539 * for this application.
540 */
541 static unsigned get_prn(unsigned count) {
542 count = count * 1103515245 + 12345;
543 return (count/65536) % PRN_MODULO;
544 }
545
546 /*
547 * Custom integer square root from
548 * http://en.wikipedia.org/wiki/Integer_square_root
549 */
550 static int sqrti(int val)
551 {
552 float d, x = val;
553
554 if (val == 0)
555 return 0;
556
557 do {
558 float y = (x + (float)val / x) / 2;
559 d = (y > x) ? y - x : x - y;
560 x = y;
561 } while (d >= 0.5);
562
563 return (int)x;
564 }
565
566 static struct commit_list *skip_away(struct commit_list *list, int count)
567 {
568 struct commit_list *cur, *previous;
569 int prn, index, i;
570
571 prn = get_prn(count);
572 index = (count * prn / PRN_MODULO) * sqrti(prn) / sqrti(PRN_MODULO);
573
574 cur = list;
575 previous = NULL;
576
577 for (i = 0; cur; cur = cur->next, i++) {
578 if (i == index) {
579 if (oidcmp(&cur->item->object.oid, current_bad_oid))
580 return cur;
581 if (previous)
582 return previous;
583 return list;
584 }
585 previous = cur;
586 }
587
588 return list;
589 }
590
591 static struct commit_list *managed_skipped(struct commit_list *list,
592 struct commit_list **tried)
593 {
594 int count, skipped_first;
595
596 *tried = NULL;
597
598 if (!skipped_revs.nr)
599 return list;
600
601 list = filter_skipped(list, tried, 0, &count, &skipped_first);
602
603 if (!skipped_first)
604 return list;
605
606 return skip_away(list, count);
607 }
608
609 static void bisect_rev_setup(struct rev_info *revs, const char *prefix,
610 const char *bad_format, const char *good_format,
611 int read_paths)
612 {
613 struct argv_array rev_argv = ARGV_ARRAY_INIT;
614 int i;
615
616 init_revisions(revs, prefix);
617 revs->abbrev = 0;
618 revs->commit_format = CMIT_FMT_UNSPECIFIED;
619
620 /* rev_argv.argv[0] will be ignored by setup_revisions */
621 argv_array_push(&rev_argv, "bisect_rev_setup");
622 argv_array_pushf(&rev_argv, bad_format, oid_to_hex(current_bad_oid));
623 for (i = 0; i < good_revs.nr; i++)
624 argv_array_pushf(&rev_argv, good_format,
625 oid_to_hex(good_revs.oid + i));
626 argv_array_push(&rev_argv, "--");
627 if (read_paths)
628 read_bisect_paths(&rev_argv);
629
630 setup_revisions(rev_argv.argc, rev_argv.argv, revs, NULL);
631 /* XXX leak rev_argv, as "revs" may still be pointing to it */
632 }
633
634 static void bisect_common(struct rev_info *revs)
635 {
636 if (prepare_revision_walk(revs))
637 die("revision walk setup failed");
638 if (revs->tree_objects)
639 mark_edges_uninteresting(revs, NULL);
640 }
641
642 static void exit_if_skipped_commits(struct commit_list *tried,
643 const struct object_id *bad)
644 {
645 if (!tried)
646 return;
647
648 printf("There are only 'skip'ped commits left to test.\n"
649 "The first %s commit could be any of:\n", term_bad);
650
651 for ( ; tried; tried = tried->next)
652 printf("%s\n", oid_to_hex(&tried->item->object.oid));
653
654 if (bad)
655 printf("%s\n", oid_to_hex(bad));
656 printf(_("We cannot bisect more!\n"));
657 exit(2);
658 }
659
660 static int is_expected_rev(const struct object_id *oid)
661 {
662 const char *filename = git_path_bisect_expected_rev();
663 struct stat st;
664 struct strbuf str = STRBUF_INIT;
665 FILE *fp;
666 int res = 0;
667
668 if (stat(filename, &st) || !S_ISREG(st.st_mode))
669 return 0;
670
671 fp = fopen(filename, "r");
672 if (!fp)
673 return 0;
674
675 if (strbuf_getline_lf(&str, fp) != EOF)
676 res = !strcmp(str.buf, oid_to_hex(oid));
677
678 strbuf_release(&str);
679 fclose(fp);
680
681 return res;
682 }
683
684 static int bisect_checkout(const unsigned char *bisect_rev, int no_checkout)
685 {
686 char bisect_rev_hex[GIT_MAX_HEXSZ + 1];
687
688 memcpy(bisect_rev_hex, sha1_to_hex(bisect_rev), GIT_SHA1_HEXSZ + 1);
689 update_ref(NULL, "BISECT_EXPECTED_REV", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
690
691 argv_checkout[2] = bisect_rev_hex;
692 if (no_checkout) {
693 update_ref(NULL, "BISECT_HEAD", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
694 } else {
695 int res;
696 res = run_command_v_opt(argv_checkout, RUN_GIT_CMD);
697 if (res)
698 exit(res);
699 }
700
701 argv_show_branch[1] = bisect_rev_hex;
702 return run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
703 }
704
705 static struct commit *get_commit_reference(const struct object_id *oid)
706 {
707 struct commit *r = lookup_commit_reference(oid->hash);
708 if (!r)
709 die(_("Not a valid commit name %s"), oid_to_hex(oid));
710 return r;
711 }
712
713 static struct commit **get_bad_and_good_commits(int *rev_nr)
714 {
715 struct commit **rev;
716 int i, n = 0;
717
718 ALLOC_ARRAY(rev, 1 + good_revs.nr);
719 rev[n++] = get_commit_reference(current_bad_oid);
720 for (i = 0; i < good_revs.nr; i++)
721 rev[n++] = get_commit_reference(good_revs.oid + i);
722 *rev_nr = n;
723
724 return rev;
725 }
726
727 static void handle_bad_merge_base(void)
728 {
729 if (is_expected_rev(current_bad_oid)) {
730 char *bad_hex = oid_to_hex(current_bad_oid);
731 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
732 if (!strcmp(term_bad, "bad") && !strcmp(term_good, "good")) {
733 fprintf(stderr, _("The merge base %s is bad.\n"
734 "This means the bug has been fixed "
735 "between %s and [%s].\n"),
736 bad_hex, bad_hex, good_hex);
737 } else if (!strcmp(term_bad, "new") && !strcmp(term_good, "old")) {
738 fprintf(stderr, _("The merge base %s is new.\n"
739 "The property has changed "
740 "between %s and [%s].\n"),
741 bad_hex, bad_hex, good_hex);
742 } else {
743 fprintf(stderr, _("The merge base %s is %s.\n"
744 "This means the first '%s' commit is "
745 "between %s and [%s].\n"),
746 bad_hex, term_bad, term_good, bad_hex, good_hex);
747 }
748 exit(3);
749 }
750
751 fprintf(stderr, _("Some %s revs are not ancestors of the %s rev.\n"
752 "git bisect cannot work properly in this case.\n"
753 "Maybe you mistook %s and %s revs?\n"),
754 term_good, term_bad, term_good, term_bad);
755 exit(1);
756 }
757
758 static void handle_skipped_merge_base(const struct object_id *mb)
759 {
760 char *mb_hex = oid_to_hex(mb);
761 char *bad_hex = oid_to_hex(current_bad_oid);
762 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
763
764 warning(_("the merge base between %s and [%s] "
765 "must be skipped.\n"
766 "So we cannot be sure the first %s commit is "
767 "between %s and %s.\n"
768 "We continue anyway."),
769 bad_hex, good_hex, term_bad, mb_hex, bad_hex);
770 free(good_hex);
771 }
772
773 /*
774 * "check_merge_bases" checks that merge bases are not "bad" (or "new").
775 *
776 * - If one is "bad" (or "new"), it means the user assumed something wrong
777 * and we must exit with a non 0 error code.
778 * - If one is "good" (or "old"), that's good, we have nothing to do.
779 * - If one is "skipped", we can't know but we should warn.
780 * - If we don't know, we should check it out and ask the user to test.
781 */
782 static void check_merge_bases(int no_checkout)
783 {
784 struct commit_list *result;
785 int rev_nr;
786 struct commit **rev = get_bad_and_good_commits(&rev_nr);
787
788 result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1);
789
790 for (; result; result = result->next) {
791 const struct object_id *mb = &result->item->object.oid;
792 if (!oidcmp(mb, current_bad_oid)) {
793 handle_bad_merge_base();
794 } else if (0 <= oid_array_lookup(&good_revs, mb)) {
795 continue;
796 } else if (0 <= oid_array_lookup(&skipped_revs, mb)) {
797 handle_skipped_merge_base(mb);
798 } else {
799 printf(_("Bisecting: a merge base must be tested\n"));
800 exit(bisect_checkout(mb->hash, no_checkout));
801 }
802 }
803
804 free(rev);
805 free_commit_list(result);
806 }
807
808 static int check_ancestors(const char *prefix)
809 {
810 struct rev_info revs;
811 struct object_array pending_copy;
812 int res;
813
814 bisect_rev_setup(&revs, prefix, "^%s", "%s", 0);
815
816 /* Save pending objects, so they can be cleaned up later. */
817 pending_copy = revs.pending;
818 revs.leak_pending = 1;
819
820 /*
821 * bisect_common calls prepare_revision_walk right away, which
822 * (together with .leak_pending = 1) makes us the sole owner of
823 * the list of pending objects.
824 */
825 bisect_common(&revs);
826 res = (revs.commits != NULL);
827
828 /* Clean up objects used, as they will be reused. */
829 clear_commit_marks_for_object_array(&pending_copy, ALL_REV_FLAGS);
830 free(pending_copy.objects);
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 const unsigned char *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.hash;
982
983 if (!hashcmp(bisect_rev, current_bad_oid->hash)) {
984 exit_if_skipped_commits(tried, current_bad_oid);
985 printf("%s is the first %s commit\n", sha1_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 /* TRANSLATORS: the last %s will be replaced with
998 "(roughly %d steps)" translation */
999 printf(Q_("Bisecting: %d revision left to test after this %s\n",
1000 "Bisecting: %d revisions left to test after this %s\n",
1001 nr), nr, steps_msg);
1002 free(steps_msg);
1003
1004 return bisect_checkout(bisect_rev, no_checkout);
1005 }
1006
1007 static inline int log2i(int n)
1008 {
1009 int log2 = 0;
1010
1011 for (; n > 1; n >>= 1)
1012 log2++;
1013
1014 return log2;
1015 }
1016
1017 static inline int exp2i(int n)
1018 {
1019 return 1 << n;
1020 }
1021
1022 /*
1023 * Estimate the number of bisect steps left (after the current step)
1024 *
1025 * For any x between 0 included and 2^n excluded, the probability for
1026 * n - 1 steps left looks like:
1027 *
1028 * P(2^n + x) == (2^n - x) / (2^n + x)
1029 *
1030 * and P(2^n + x) < 0.5 means 2^n < 3x
1031 */
1032 int estimate_bisect_steps(int all)
1033 {
1034 int n, x, e;
1035
1036 if (all < 3)
1037 return 0;
1038
1039 n = log2i(all);
1040 e = exp2i(n);
1041 x = all - e;
1042
1043 return (e < 3 * x) ? n : n - 1;
1044 }