Merge branch 'ps/t1509-chroot-test-fixup'
[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 sha1_array good_revs;
16 static struct sha1_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 static const char *argv_update_ref[] = {"update-ref", "--no-deref", "BISECT_HEAD", 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 hashcmp(a->commit->object.sha1, b->commit->object.sha1);
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 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, sizeof(*array), compare_commit_dist);
220 for (p = list, i = 0; i < cnt; i++) {
221 char buf[100]; /* enough for dist=%d */
222 struct object *obj = &(array[i].commit->object);
223
224 snprintf(buf, sizeof(buf), "dist=%d", array[i].distance);
225 add_name_decoration(DECORATION_NONE, buf, obj);
226
227 p->item = array[i].commit;
228 p = p->next;
229 }
230 if (p)
231 p->next = NULL;
232 free(array);
233 return list;
234 }
235
236 /*
237 * zero or positive weight is the number of interesting commits it can
238 * reach, including itself. Especially, weight = 0 means it does not
239 * reach any tree-changing commits (e.g. just above uninteresting one
240 * but traversal is with pathspec).
241 *
242 * weight = -1 means it has one parent and its distance is yet to
243 * be computed.
244 *
245 * weight = -2 means it has more than one parent and its distance is
246 * unknown. After running count_distance() first, they will get zero
247 * or positive distance.
248 */
249 static struct commit_list *do_find_bisection(struct commit_list *list,
250 int nr, int *weights,
251 int find_all)
252 {
253 int n, counted;
254 struct commit_list *p;
255
256 counted = 0;
257
258 for (n = 0, p = list; p; p = p->next) {
259 struct commit *commit = p->item;
260 unsigned flags = commit->object.flags;
261
262 p->item->util = &weights[n++];
263 switch (count_interesting_parents(commit)) {
264 case 0:
265 if (!(flags & TREESAME)) {
266 weight_set(p, 1);
267 counted++;
268 show_list("bisection 2 count one",
269 counted, nr, list);
270 }
271 /*
272 * otherwise, it is known not to reach any
273 * tree-changing commit and gets weight 0.
274 */
275 break;
276 case 1:
277 weight_set(p, -1);
278 break;
279 default:
280 weight_set(p, -2);
281 break;
282 }
283 }
284
285 show_list("bisection 2 initialize", counted, nr, list);
286
287 /*
288 * If you have only one parent in the resulting set
289 * then you can reach one commit more than that parent
290 * can reach. So we do not have to run the expensive
291 * count_distance() for single strand of pearls.
292 *
293 * However, if you have more than one parents, you cannot
294 * just add their distance and one for yourself, since
295 * they usually reach the same ancestor and you would
296 * end up counting them twice that way.
297 *
298 * So we will first count distance of merges the usual
299 * way, and then fill the blanks using cheaper algorithm.
300 */
301 for (p = list; p; p = p->next) {
302 if (p->item->object.flags & UNINTERESTING)
303 continue;
304 if (weight(p) != -2)
305 continue;
306 weight_set(p, count_distance(p));
307 clear_distance(list);
308
309 /* Does it happen to be at exactly half-way? */
310 if (!find_all && halfway(p, nr))
311 return p;
312 counted++;
313 }
314
315 show_list("bisection 2 count_distance", counted, nr, list);
316
317 while (counted < nr) {
318 for (p = list; p; p = p->next) {
319 struct commit_list *q;
320 unsigned flags = p->item->object.flags;
321
322 if (0 <= weight(p))
323 continue;
324 for (q = p->item->parents; q; q = q->next) {
325 if (q->item->object.flags & UNINTERESTING)
326 continue;
327 if (0 <= weight(q))
328 break;
329 }
330 if (!q)
331 continue;
332
333 /*
334 * weight for p is unknown but q is known.
335 * add one for p itself if p is to be counted,
336 * otherwise inherit it from q directly.
337 */
338 if (!(flags & TREESAME)) {
339 weight_set(p, weight(q)+1);
340 counted++;
341 show_list("bisection 2 count one",
342 counted, nr, list);
343 }
344 else
345 weight_set(p, weight(q));
346
347 /* Does it happen to be at exactly half-way? */
348 if (!find_all && halfway(p, nr))
349 return p;
350 }
351 }
352
353 show_list("bisection 2 counted all", counted, nr, list);
354
355 if (!find_all)
356 return best_bisection(list, nr);
357 else
358 return best_bisection_sorted(list, nr);
359 }
360
361 struct commit_list *find_bisection(struct commit_list *list,
362 int *reaches, int *all,
363 int find_all)
364 {
365 int nr, on_list;
366 struct commit_list *p, *best, *next, *last;
367 int *weights;
368
369 show_list("bisection 2 entry", 0, 0, list);
370
371 /*
372 * Count the number of total and tree-changing items on the
373 * list, while reversing the list.
374 */
375 for (nr = on_list = 0, last = NULL, p = list;
376 p;
377 p = next) {
378 unsigned flags = p->item->object.flags;
379
380 next = p->next;
381 if (flags & UNINTERESTING)
382 continue;
383 p->next = last;
384 last = p;
385 if (!(flags & TREESAME))
386 nr++;
387 on_list++;
388 }
389 list = last;
390 show_list("bisection 2 sorted", 0, nr, list);
391
392 *all = nr;
393 weights = xcalloc(on_list, sizeof(*weights));
394
395 /* Do the real work of finding bisection commit. */
396 best = do_find_bisection(list, nr, weights, find_all);
397 if (best) {
398 if (!find_all)
399 best->next = NULL;
400 *reaches = weight(best);
401 }
402 free(weights);
403 return best;
404 }
405
406 static int register_ref(const char *refname, const struct object_id *oid,
407 int flags, void *cb_data)
408 {
409 struct strbuf good_prefix = STRBUF_INIT;
410 strbuf_addstr(&good_prefix, term_good);
411 strbuf_addstr(&good_prefix, "-");
412
413 if (!strcmp(refname, term_bad)) {
414 current_bad_oid = xmalloc(sizeof(*current_bad_oid));
415 oidcpy(current_bad_oid, oid);
416 } else if (starts_with(refname, good_prefix.buf)) {
417 sha1_array_append(&good_revs, oid->hash);
418 } else if (starts_with(refname, "skip-")) {
419 sha1_array_append(&skipped_revs, oid->hash);
420 }
421
422 strbuf_release(&good_prefix);
423
424 return 0;
425 }
426
427 static int read_bisect_refs(void)
428 {
429 return for_each_ref_in("refs/bisect/", register_ref, NULL);
430 }
431
432 static void read_bisect_paths(struct argv_array *array)
433 {
434 struct strbuf str = STRBUF_INIT;
435 const char *filename = git_path("BISECT_NAMES");
436 FILE *fp = fopen(filename, "r");
437
438 if (!fp)
439 die_errno("Could not open file '%s'", filename);
440
441 while (strbuf_getline(&str, fp, '\n') != EOF) {
442 strbuf_trim(&str);
443 if (sq_dequote_to_argv_array(str.buf, array))
444 die("Badly quoted content in file '%s': %s",
445 filename, str.buf);
446 }
447
448 strbuf_release(&str);
449 fclose(fp);
450 }
451
452 static char *join_sha1_array_hex(struct sha1_array *array, char delim)
453 {
454 struct strbuf joined_hexs = STRBUF_INIT;
455 int i;
456
457 for (i = 0; i < array->nr; i++) {
458 strbuf_addstr(&joined_hexs, sha1_to_hex(array->sha1[i]));
459 if (i + 1 < array->nr)
460 strbuf_addch(&joined_hexs, delim);
461 }
462
463 return strbuf_detach(&joined_hexs, NULL);
464 }
465
466 /*
467 * In this function, passing a not NULL skipped_first is very special.
468 * It means that we want to know if the first commit in the list is
469 * skipped because we will want to test a commit away from it if it is
470 * indeed skipped.
471 * So if the first commit is skipped, we cannot take the shortcut to
472 * just "return list" when we find the first non skipped commit, we
473 * have to return a fully filtered list.
474 *
475 * We use (*skipped_first == -1) to mean "it has been found that the
476 * first commit is not skipped". In this case *skipped_first is set back
477 * to 0 just before the function returns.
478 */
479 struct commit_list *filter_skipped(struct commit_list *list,
480 struct commit_list **tried,
481 int show_all,
482 int *count,
483 int *skipped_first)
484 {
485 struct commit_list *filtered = NULL, **f = &filtered;
486
487 *tried = NULL;
488
489 if (skipped_first)
490 *skipped_first = 0;
491 if (count)
492 *count = 0;
493
494 if (!skipped_revs.nr)
495 return list;
496
497 while (list) {
498 struct commit_list *next = list->next;
499 list->next = NULL;
500 if (0 <= sha1_array_lookup(&skipped_revs,
501 list->item->object.sha1)) {
502 if (skipped_first && !*skipped_first)
503 *skipped_first = 1;
504 /* Move current to tried list */
505 *tried = list;
506 tried = &list->next;
507 } else {
508 if (!show_all) {
509 if (!skipped_first || !*skipped_first)
510 return list;
511 } else if (skipped_first && !*skipped_first) {
512 /* This means we know it's not skipped */
513 *skipped_first = -1;
514 }
515 /* Move current to filtered list */
516 *f = list;
517 f = &list->next;
518 if (count)
519 (*count)++;
520 }
521 list = next;
522 }
523
524 if (skipped_first && *skipped_first == -1)
525 *skipped_first = 0;
526
527 return filtered;
528 }
529
530 #define PRN_MODULO 32768
531
532 /*
533 * This is a pseudo random number generator based on "man 3 rand".
534 * It is not used properly because the seed is the argument and it
535 * is increased by one between each call, but that should not matter
536 * for this application.
537 */
538 static unsigned get_prn(unsigned count) {
539 count = count * 1103515245 + 12345;
540 return (count/65536) % PRN_MODULO;
541 }
542
543 /*
544 * Custom integer square root from
545 * http://en.wikipedia.org/wiki/Integer_square_root
546 */
547 static int sqrti(int val)
548 {
549 float d, x = val;
550
551 if (val == 0)
552 return 0;
553
554 do {
555 float y = (x + (float)val / x) / 2;
556 d = (y > x) ? y - x : x - y;
557 x = y;
558 } while (d >= 0.5);
559
560 return (int)x;
561 }
562
563 static struct commit_list *skip_away(struct commit_list *list, int count)
564 {
565 struct commit_list *cur, *previous;
566 int prn, index, i;
567
568 prn = get_prn(count);
569 index = (count * prn / PRN_MODULO) * sqrti(prn) / sqrti(PRN_MODULO);
570
571 cur = list;
572 previous = NULL;
573
574 for (i = 0; cur; cur = cur->next, i++) {
575 if (i == index) {
576 if (hashcmp(cur->item->object.sha1, current_bad_oid->hash))
577 return cur;
578 if (previous)
579 return previous;
580 return list;
581 }
582 previous = cur;
583 }
584
585 return list;
586 }
587
588 static struct commit_list *managed_skipped(struct commit_list *list,
589 struct commit_list **tried)
590 {
591 int count, skipped_first;
592
593 *tried = NULL;
594
595 if (!skipped_revs.nr)
596 return list;
597
598 list = filter_skipped(list, tried, 0, &count, &skipped_first);
599
600 if (!skipped_first)
601 return list;
602
603 return skip_away(list, count);
604 }
605
606 static void bisect_rev_setup(struct rev_info *revs, const char *prefix,
607 const char *bad_format, const char *good_format,
608 int read_paths)
609 {
610 struct argv_array rev_argv = ARGV_ARRAY_INIT;
611 int i;
612
613 init_revisions(revs, prefix);
614 revs->abbrev = 0;
615 revs->commit_format = CMIT_FMT_UNSPECIFIED;
616
617 /* rev_argv.argv[0] will be ignored by setup_revisions */
618 argv_array_push(&rev_argv, "bisect_rev_setup");
619 argv_array_pushf(&rev_argv, bad_format, oid_to_hex(current_bad_oid));
620 for (i = 0; i < good_revs.nr; i++)
621 argv_array_pushf(&rev_argv, good_format,
622 sha1_to_hex(good_revs.sha1[i]));
623 argv_array_push(&rev_argv, "--");
624 if (read_paths)
625 read_bisect_paths(&rev_argv);
626
627 setup_revisions(rev_argv.argc, rev_argv.argv, revs, NULL);
628 /* XXX leak rev_argv, as "revs" may still be pointing to it */
629 }
630
631 static void bisect_common(struct rev_info *revs)
632 {
633 if (prepare_revision_walk(revs))
634 die("revision walk setup failed");
635 if (revs->tree_objects)
636 mark_edges_uninteresting(revs, NULL);
637 }
638
639 static void exit_if_skipped_commits(struct commit_list *tried,
640 const struct object_id *bad)
641 {
642 if (!tried)
643 return;
644
645 printf("There are only 'skip'ped commits left to test.\n"
646 "The first %s commit could be any of:\n", term_bad);
647 print_commit_list(tried, "%s\n", "%s\n");
648 if (bad)
649 printf("%s\n", oid_to_hex(bad));
650 printf("We cannot bisect more!\n");
651 exit(2);
652 }
653
654 static int is_expected_rev(const struct object_id *oid)
655 {
656 const char *filename = git_path("BISECT_EXPECTED_REV");
657 struct stat st;
658 struct strbuf str = STRBUF_INIT;
659 FILE *fp;
660 int res = 0;
661
662 if (stat(filename, &st) || !S_ISREG(st.st_mode))
663 return 0;
664
665 fp = fopen(filename, "r");
666 if (!fp)
667 return 0;
668
669 if (strbuf_getline(&str, fp, '\n') != EOF)
670 res = !strcmp(str.buf, oid_to_hex(oid));
671
672 strbuf_release(&str);
673 fclose(fp);
674
675 return res;
676 }
677
678 static void mark_expected_rev(char *bisect_rev_hex)
679 {
680 int len = strlen(bisect_rev_hex);
681 const char *filename = git_path("BISECT_EXPECTED_REV");
682 int fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
683
684 if (fd < 0)
685 die_errno("could not create file '%s'", filename);
686
687 bisect_rev_hex[len] = '\n';
688 write_or_die(fd, bisect_rev_hex, len + 1);
689 bisect_rev_hex[len] = '\0';
690
691 if (close(fd) < 0)
692 die("closing file %s: %s", filename, strerror(errno));
693 }
694
695 static int bisect_checkout(char *bisect_rev_hex, int no_checkout)
696 {
697
698 mark_expected_rev(bisect_rev_hex);
699
700 argv_checkout[2] = bisect_rev_hex;
701 if (no_checkout) {
702 argv_update_ref[3] = bisect_rev_hex;
703 if (run_command_v_opt(argv_update_ref, RUN_GIT_CMD))
704 die("update-ref --no-deref HEAD failed on %s",
705 bisect_rev_hex);
706 } else {
707 int res;
708 res = run_command_v_opt(argv_checkout, RUN_GIT_CMD);
709 if (res)
710 exit(res);
711 }
712
713 argv_show_branch[1] = bisect_rev_hex;
714 return run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
715 }
716
717 static struct commit *get_commit_reference(const unsigned char *sha1)
718 {
719 struct commit *r = lookup_commit_reference(sha1);
720 if (!r)
721 die("Not a valid commit name %s", sha1_to_hex(sha1));
722 return r;
723 }
724
725 static struct commit **get_bad_and_good_commits(int *rev_nr)
726 {
727 int len = 1 + good_revs.nr;
728 struct commit **rev = xmalloc(len * sizeof(*rev));
729 int i, n = 0;
730
731 rev[n++] = get_commit_reference(current_bad_oid->hash);
732 for (i = 0; i < good_revs.nr; i++)
733 rev[n++] = get_commit_reference(good_revs.sha1[i]);
734 *rev_nr = n;
735
736 return rev;
737 }
738
739 static void handle_bad_merge_base(void)
740 {
741 if (is_expected_rev(current_bad_oid)) {
742 char *bad_hex = oid_to_hex(current_bad_oid);
743 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
744 if (!strcmp(term_bad, "bad") && !strcmp(term_good, "good")) {
745 fprintf(stderr, "The merge base %s is bad.\n"
746 "This means the bug has been fixed "
747 "between %s and [%s].\n",
748 bad_hex, bad_hex, good_hex);
749 } else {
750 fprintf(stderr, "The merge base %s is %s.\n"
751 "This means the first '%s' commit is "
752 "between %s and [%s].\n",
753 bad_hex, term_bad, term_good, bad_hex, good_hex);
754 }
755 exit(3);
756 }
757
758 fprintf(stderr, "Some %s revs are not ancestor of the %s rev.\n"
759 "git bisect cannot work properly in this case.\n"
760 "Maybe you mistook %s and %s revs?\n",
761 term_good, term_bad, term_good, term_bad);
762 exit(1);
763 }
764
765 static void handle_skipped_merge_base(const unsigned char *mb)
766 {
767 char *mb_hex = sha1_to_hex(mb);
768 char *bad_hex = sha1_to_hex(current_bad_oid->hash);
769 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
770
771 warning("the merge base between %s and [%s] "
772 "must be skipped.\n"
773 "So we cannot be sure the first %s commit is "
774 "between %s and %s.\n"
775 "We continue anyway.",
776 bad_hex, good_hex, term_bad, mb_hex, bad_hex);
777 free(good_hex);
778 }
779
780 /*
781 * "check_merge_bases" checks that merge bases are not "bad".
782 *
783 * - If one is "bad", it means the user assumed something wrong
784 * and we must exit with a non 0 error code.
785 * - If one is "good", that's good, we have nothing to do.
786 * - If one is "skipped", we can't know but we should warn.
787 * - If we don't know, we should check it out and ask the user to test.
788 */
789 static void check_merge_bases(int no_checkout)
790 {
791 struct commit_list *result;
792 int rev_nr;
793 struct commit **rev = get_bad_and_good_commits(&rev_nr);
794
795 result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1);
796
797 for (; result; result = result->next) {
798 const unsigned char *mb = result->item->object.sha1;
799 if (!hashcmp(mb, current_bad_oid->hash)) {
800 handle_bad_merge_base();
801 } else if (0 <= sha1_array_lookup(&good_revs, mb)) {
802 continue;
803 } else if (0 <= sha1_array_lookup(&skipped_revs, mb)) {
804 handle_skipped_merge_base(mb);
805 } else {
806 printf("Bisecting: a merge base must be tested\n");
807 exit(bisect_checkout(sha1_to_hex(mb), no_checkout));
808 }
809 }
810
811 free(rev);
812 free_commit_list(result);
813 }
814
815 static int check_ancestors(const char *prefix)
816 {
817 struct rev_info revs;
818 struct object_array pending_copy;
819 int res;
820
821 bisect_rev_setup(&revs, prefix, "^%s", "%s", 0);
822
823 /* Save pending objects, so they can be cleaned up later. */
824 pending_copy = revs.pending;
825 revs.leak_pending = 1;
826
827 /*
828 * bisect_common calls prepare_revision_walk right away, which
829 * (together with .leak_pending = 1) makes us the sole owner of
830 * the list of pending objects.
831 */
832 bisect_common(&revs);
833 res = (revs.commits != NULL);
834
835 /* Clean up objects used, as they will be reused. */
836 clear_commit_marks_for_object_array(&pending_copy, ALL_REV_FLAGS);
837 free(pending_copy.objects);
838
839 return res;
840 }
841
842 /*
843 * "check_good_are_ancestors_of_bad" checks that all "good" revs are
844 * ancestor of the "bad" rev.
845 *
846 * If that's not the case, we need to check the merge bases.
847 * If a merge base must be tested by the user, its source code will be
848 * checked out to be tested by the user and we will exit.
849 */
850 static void check_good_are_ancestors_of_bad(const char *prefix, int no_checkout)
851 {
852 char *filename = git_pathdup("BISECT_ANCESTORS_OK");
853 struct stat st;
854 int fd;
855
856 if (!current_bad_oid)
857 die("a %s revision is needed", term_bad);
858
859 /* Check if file BISECT_ANCESTORS_OK exists. */
860 if (!stat(filename, &st) && S_ISREG(st.st_mode))
861 goto done;
862
863 /* Bisecting with no good rev is ok. */
864 if (good_revs.nr == 0)
865 goto done;
866
867 /* Check if all good revs are ancestor of the bad rev. */
868 if (check_ancestors(prefix))
869 check_merge_bases(no_checkout);
870
871 /* Create file BISECT_ANCESTORS_OK. */
872 fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
873 if (fd < 0)
874 warning("could not create file '%s': %s",
875 filename, strerror(errno));
876 else
877 close(fd);
878 done:
879 free(filename);
880 }
881
882 /*
883 * This does "git diff-tree --pretty COMMIT" without one fork+exec.
884 */
885 static void show_diff_tree(const char *prefix, struct commit *commit)
886 {
887 struct rev_info opt;
888
889 /* diff-tree init */
890 init_revisions(&opt, prefix);
891 git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
892 opt.abbrev = 0;
893 opt.diff = 1;
894
895 /* This is what "--pretty" does */
896 opt.verbose_header = 1;
897 opt.use_terminator = 0;
898 opt.commit_format = CMIT_FMT_DEFAULT;
899
900 /* diff-tree init */
901 if (!opt.diffopt.output_format)
902 opt.diffopt.output_format = DIFF_FORMAT_RAW;
903
904 log_tree_commit(&opt, commit);
905 }
906
907 /*
908 * The terms used for this bisect session are stored in BISECT_TERMS.
909 * We read them and store them to adapt the messages accordingly.
910 * Default is bad/good.
911 */
912 void read_bisect_terms(const char **read_bad, const char **read_good)
913 {
914 struct strbuf str = STRBUF_INIT;
915 const char *filename = git_path("BISECT_TERMS");
916 FILE *fp = fopen(filename, "r");
917
918 if (!fp) {
919 if (errno == ENOENT) {
920 *read_bad = "bad";
921 *read_good = "good";
922 return;
923 } else {
924 die("could not read file '%s': %s", filename,
925 strerror(errno));
926 }
927 } else {
928 strbuf_getline(&str, fp, '\n');
929 *read_bad = strbuf_detach(&str, NULL);
930 strbuf_getline(&str, fp, '\n');
931 *read_good = strbuf_detach(&str, NULL);
932 }
933 strbuf_release(&str);
934 fclose(fp);
935 }
936
937 /*
938 * We use the convention that exiting with an exit code 10 means that
939 * the bisection process finished successfully.
940 * In this case the calling shell script should exit 0.
941 *
942 * If no_checkout is non-zero, the bisection process does not
943 * checkout the trial commit but instead simply updates BISECT_HEAD.
944 */
945 int bisect_next_all(const char *prefix, int no_checkout)
946 {
947 struct rev_info revs;
948 struct commit_list *tried;
949 int reaches = 0, all = 0, nr, steps;
950 const unsigned char *bisect_rev;
951 char bisect_rev_hex[GIT_SHA1_HEXSZ + 1];
952
953 read_bisect_terms(&term_bad, &term_good);
954 if (read_bisect_refs())
955 die("reading bisect refs failed");
956
957 check_good_are_ancestors_of_bad(prefix, no_checkout);
958
959 bisect_rev_setup(&revs, prefix, "%s", "^%s", 1);
960 revs.limited = 1;
961
962 bisect_common(&revs);
963
964 revs.commits = find_bisection(revs.commits, &reaches, &all,
965 !!skipped_revs.nr);
966 revs.commits = managed_skipped(revs.commits, &tried);
967
968 if (!revs.commits) {
969 /*
970 * We should exit here only if the "bad"
971 * commit is also a "skip" commit.
972 */
973 exit_if_skipped_commits(tried, NULL);
974
975 printf("%s was both %s and %s\n",
976 oid_to_hex(current_bad_oid),
977 term_good,
978 term_bad);
979 exit(1);
980 }
981
982 if (!all) {
983 fprintf(stderr, "No testable commit found.\n"
984 "Maybe you started with bad path parameters?\n");
985 exit(4);
986 }
987
988 bisect_rev = revs.commits->item->object.sha1;
989 memcpy(bisect_rev_hex, sha1_to_hex(bisect_rev), GIT_SHA1_HEXSZ + 1);
990
991 if (!hashcmp(bisect_rev, current_bad_oid->hash)) {
992 exit_if_skipped_commits(tried, current_bad_oid);
993 printf("%s is the first %s commit\n", bisect_rev_hex,
994 term_bad);
995 show_diff_tree(prefix, revs.commits->item);
996 /* This means the bisection process succeeded. */
997 exit(10);
998 }
999
1000 nr = all - reaches - 1;
1001 steps = estimate_bisect_steps(all);
1002 printf("Bisecting: %d revision%s left to test after this "
1003 "(roughly %d step%s)\n", nr, (nr == 1 ? "" : "s"),
1004 steps, (steps == 1 ? "" : "s"));
1005
1006 return bisect_checkout(bisect_rev_hex, 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 }