Documentation/githooks: Fix linkgit
[git.git] / bisect.c
blobbd1b7b5dac81ada592a16630214d1f2cbb655b88
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"
15 static struct sha1_array good_revs;
16 static struct sha1_array skipped_revs;
18 static const unsigned char *current_bad_sha1;
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};
24 /* bits #0-15 in revision.h */
26 #define COUNTED (1u<<16)
29 * This is a truly stupid algorithm, but it's only
30 * used for bisection, and we just don't care enough.
32 * We care just barely enough to avoid recursing for
33 * non-merge entries.
35 static int count_distance(struct commit_list *entry)
37 int nr = 0;
39 while (entry) {
40 struct commit *commit = entry->item;
41 struct commit_list *p;
43 if (commit->object.flags & (UNINTERESTING | COUNTED))
44 break;
45 if (!(commit->object.flags & TREESAME))
46 nr++;
47 commit->object.flags |= COUNTED;
48 p = commit->parents;
49 entry = p;
50 if (p) {
51 p = p->next;
52 while (p) {
53 nr += count_distance(p);
54 p = p->next;
59 return nr;
62 static void clear_distance(struct commit_list *list)
64 while (list) {
65 struct commit *commit = list->item;
66 commit->object.flags &= ~COUNTED;
67 list = list->next;
71 #define DEBUG_BISECT 0
73 static inline int weight(struct commit_list *elem)
75 return *((int*)(elem->item->util));
78 static inline void weight_set(struct commit_list *elem, int weight)
80 *((int*)(elem->item->util)) = weight;
83 static int count_interesting_parents(struct commit *commit)
85 struct commit_list *p;
86 int count;
88 for (count = 0, p = commit->parents; p; p = p->next) {
89 if (p->item->object.flags & UNINTERESTING)
90 continue;
91 count++;
93 return count;
96 static inline int halfway(struct commit_list *p, int nr)
99 * Don't short-cut something we are not going to return!
101 if (p->item->object.flags & TREESAME)
102 return 0;
103 if (DEBUG_BISECT)
104 return 0;
106 * 2 and 3 are halfway of 5.
107 * 3 is halfway of 6 but 2 and 4 are not.
109 switch (2 * weight(p) - nr) {
110 case -1: case 0: case 1:
111 return 1;
112 default:
113 return 0;
117 #if !DEBUG_BISECT
118 #define show_list(a,b,c,d) do { ; } while (0)
119 #else
120 static void show_list(const char *debug, int counted, int nr,
121 struct commit_list *list)
123 struct commit_list *p;
125 fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr);
127 for (p = list; p; p = p->next) {
128 struct commit_list *pp;
129 struct commit *commit = p->item;
130 unsigned flags = commit->object.flags;
131 enum object_type type;
132 unsigned long size;
133 char *buf = read_sha1_file(commit->object.sha1, &type, &size);
134 const char *subject_start;
135 int subject_len;
137 fprintf(stderr, "%c%c%c ",
138 (flags & TREESAME) ? ' ' : 'T',
139 (flags & UNINTERESTING) ? 'U' : ' ',
140 (flags & COUNTED) ? 'C' : ' ');
141 if (commit->util)
142 fprintf(stderr, "%3d", weight(p));
143 else
144 fprintf(stderr, "---");
145 fprintf(stderr, " %.*s", 8, sha1_to_hex(commit->object.sha1));
146 for (pp = commit->parents; pp; pp = pp->next)
147 fprintf(stderr, " %.*s", 8,
148 sha1_to_hex(pp->item->object.sha1));
150 subject_len = find_commit_subject(buf, &subject_start);
151 if (subject_len)
152 fprintf(stderr, " %.*s", subject_len, subject_start);
153 fprintf(stderr, "\n");
156 #endif /* DEBUG_BISECT */
158 static struct commit_list *best_bisection(struct commit_list *list, int nr)
160 struct commit_list *p, *best;
161 int best_distance = -1;
163 best = list;
164 for (p = list; p; p = p->next) {
165 int distance;
166 unsigned flags = p->item->object.flags;
168 if (flags & TREESAME)
169 continue;
170 distance = weight(p);
171 if (nr - distance < distance)
172 distance = nr - distance;
173 if (distance > best_distance) {
174 best = p;
175 best_distance = distance;
179 return best;
182 struct commit_dist {
183 struct commit *commit;
184 int distance;
187 static int compare_commit_dist(const void *a_, const void *b_)
189 struct commit_dist *a, *b;
191 a = (struct commit_dist *)a_;
192 b = (struct commit_dist *)b_;
193 if (a->distance != b->distance)
194 return b->distance - a->distance; /* desc sort */
195 return hashcmp(a->commit->object.sha1, b->commit->object.sha1);
198 static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
200 struct commit_list *p;
201 struct commit_dist *array = xcalloc(nr, sizeof(*array));
202 int cnt, i;
204 for (p = list, cnt = 0; p; p = p->next) {
205 int distance;
206 unsigned flags = p->item->object.flags;
208 if (flags & TREESAME)
209 continue;
210 distance = weight(p);
211 if (nr - distance < distance)
212 distance = nr - distance;
213 array[cnt].commit = p->item;
214 array[cnt].distance = distance;
215 cnt++;
217 qsort(array, cnt, sizeof(*array), compare_commit_dist);
218 for (p = list, i = 0; i < cnt; i++) {
219 struct name_decoration *r = xmalloc(sizeof(*r) + 100);
220 struct object *obj = &(array[i].commit->object);
222 sprintf(r->name, "dist=%d", array[i].distance);
223 r->next = add_decoration(&name_decoration, obj, r);
224 p->item = array[i].commit;
225 p = p->next;
227 if (p)
228 p->next = NULL;
229 free(array);
230 return list;
234 * zero or positive weight is the number of interesting commits it can
235 * reach, including itself. Especially, weight = 0 means it does not
236 * reach any tree-changing commits (e.g. just above uninteresting one
237 * but traversal is with pathspec).
239 * weight = -1 means it has one parent and its distance is yet to
240 * be computed.
242 * weight = -2 means it has more than one parent and its distance is
243 * unknown. After running count_distance() first, they will get zero
244 * or positive distance.
246 static struct commit_list *do_find_bisection(struct commit_list *list,
247 int nr, int *weights,
248 int find_all)
250 int n, counted;
251 struct commit_list *p;
253 counted = 0;
255 for (n = 0, p = list; p; p = p->next) {
256 struct commit *commit = p->item;
257 unsigned flags = commit->object.flags;
259 p->item->util = &weights[n++];
260 switch (count_interesting_parents(commit)) {
261 case 0:
262 if (!(flags & TREESAME)) {
263 weight_set(p, 1);
264 counted++;
265 show_list("bisection 2 count one",
266 counted, nr, list);
269 * otherwise, it is known not to reach any
270 * tree-changing commit and gets weight 0.
272 break;
273 case 1:
274 weight_set(p, -1);
275 break;
276 default:
277 weight_set(p, -2);
278 break;
282 show_list("bisection 2 initialize", counted, nr, list);
285 * If you have only one parent in the resulting set
286 * then you can reach one commit more than that parent
287 * can reach. So we do not have to run the expensive
288 * count_distance() for single strand of pearls.
290 * However, if you have more than one parents, you cannot
291 * just add their distance and one for yourself, since
292 * they usually reach the same ancestor and you would
293 * end up counting them twice that way.
295 * So we will first count distance of merges the usual
296 * way, and then fill the blanks using cheaper algorithm.
298 for (p = list; p; p = p->next) {
299 if (p->item->object.flags & UNINTERESTING)
300 continue;
301 if (weight(p) != -2)
302 continue;
303 weight_set(p, count_distance(p));
304 clear_distance(list);
306 /* Does it happen to be at exactly half-way? */
307 if (!find_all && halfway(p, nr))
308 return p;
309 counted++;
312 show_list("bisection 2 count_distance", counted, nr, list);
314 while (counted < nr) {
315 for (p = list; p; p = p->next) {
316 struct commit_list *q;
317 unsigned flags = p->item->object.flags;
319 if (0 <= weight(p))
320 continue;
321 for (q = p->item->parents; q; q = q->next) {
322 if (q->item->object.flags & UNINTERESTING)
323 continue;
324 if (0 <= weight(q))
325 break;
327 if (!q)
328 continue;
331 * weight for p is unknown but q is known.
332 * add one for p itself if p is to be counted,
333 * otherwise inherit it from q directly.
335 if (!(flags & TREESAME)) {
336 weight_set(p, weight(q)+1);
337 counted++;
338 show_list("bisection 2 count one",
339 counted, nr, list);
341 else
342 weight_set(p, weight(q));
344 /* Does it happen to be at exactly half-way? */
345 if (!find_all && halfway(p, nr))
346 return p;
350 show_list("bisection 2 counted all", counted, nr, list);
352 if (!find_all)
353 return best_bisection(list, nr);
354 else
355 return best_bisection_sorted(list, nr);
358 struct commit_list *find_bisection(struct commit_list *list,
359 int *reaches, int *all,
360 int find_all)
362 int nr, on_list;
363 struct commit_list *p, *best, *next, *last;
364 int *weights;
366 show_list("bisection 2 entry", 0, 0, list);
369 * Count the number of total and tree-changing items on the
370 * list, while reversing the list.
372 for (nr = on_list = 0, last = NULL, p = list;
374 p = next) {
375 unsigned flags = p->item->object.flags;
377 next = p->next;
378 if (flags & UNINTERESTING)
379 continue;
380 p->next = last;
381 last = p;
382 if (!(flags & TREESAME))
383 nr++;
384 on_list++;
386 list = last;
387 show_list("bisection 2 sorted", 0, nr, list);
389 *all = nr;
390 weights = xcalloc(on_list, sizeof(*weights));
392 /* Do the real work of finding bisection commit. */
393 best = do_find_bisection(list, nr, weights, find_all);
394 if (best) {
395 if (!find_all)
396 best->next = NULL;
397 *reaches = weight(best);
399 free(weights);
400 return best;
403 static int register_ref(const char *refname, const unsigned char *sha1,
404 int flags, void *cb_data)
406 if (!strcmp(refname, "bad")) {
407 current_bad_sha1 = sha1;
408 } else if (!prefixcmp(refname, "good-")) {
409 sha1_array_append(&good_revs, sha1);
410 } else if (!prefixcmp(refname, "skip-")) {
411 sha1_array_append(&skipped_revs, sha1);
414 return 0;
417 static int read_bisect_refs(void)
419 return for_each_ref_in("refs/bisect/", register_ref, NULL);
422 static void read_bisect_paths(struct argv_array *array)
424 struct strbuf str = STRBUF_INIT;
425 const char *filename = git_path("BISECT_NAMES");
426 FILE *fp = fopen(filename, "r");
428 if (!fp)
429 die_errno("Could not open file '%s'", filename);
431 while (strbuf_getline(&str, fp, '\n') != EOF) {
432 strbuf_trim(&str);
433 if (sq_dequote_to_argv_array(str.buf, array))
434 die("Badly quoted content in file '%s': %s",
435 filename, str.buf);
438 strbuf_release(&str);
439 fclose(fp);
442 static char *join_sha1_array_hex(struct sha1_array *array, char delim)
444 struct strbuf joined_hexs = STRBUF_INIT;
445 int i;
447 for (i = 0; i < array->nr; i++) {
448 strbuf_addstr(&joined_hexs, sha1_to_hex(array->sha1[i]));
449 if (i + 1 < array->nr)
450 strbuf_addch(&joined_hexs, delim);
453 return strbuf_detach(&joined_hexs, NULL);
457 * In this function, passing a not NULL skipped_first is very special.
458 * It means that we want to know if the first commit in the list is
459 * skipped because we will want to test a commit away from it if it is
460 * indeed skipped.
461 * So if the first commit is skipped, we cannot take the shortcut to
462 * just "return list" when we find the first non skipped commit, we
463 * have to return a fully filtered list.
465 * We use (*skipped_first == -1) to mean "it has been found that the
466 * first commit is not skipped". In this case *skipped_first is set back
467 * to 0 just before the function returns.
469 struct commit_list *filter_skipped(struct commit_list *list,
470 struct commit_list **tried,
471 int show_all,
472 int *count,
473 int *skipped_first)
475 struct commit_list *filtered = NULL, **f = &filtered;
477 *tried = NULL;
479 if (skipped_first)
480 *skipped_first = 0;
481 if (count)
482 *count = 0;
484 if (!skipped_revs.nr)
485 return list;
487 while (list) {
488 struct commit_list *next = list->next;
489 list->next = NULL;
490 if (0 <= sha1_array_lookup(&skipped_revs,
491 list->item->object.sha1)) {
492 if (skipped_first && !*skipped_first)
493 *skipped_first = 1;
494 /* Move current to tried list */
495 *tried = list;
496 tried = &list->next;
497 } else {
498 if (!show_all) {
499 if (!skipped_first || !*skipped_first)
500 return list;
501 } else if (skipped_first && !*skipped_first) {
502 /* This means we know it's not skipped */
503 *skipped_first = -1;
505 /* Move current to filtered list */
506 *f = list;
507 f = &list->next;
508 if (count)
509 (*count)++;
511 list = next;
514 if (skipped_first && *skipped_first == -1)
515 *skipped_first = 0;
517 return filtered;
520 #define PRN_MODULO 32768
523 * This is a pseudo random number generator based on "man 3 rand".
524 * It is not used properly because the seed is the argument and it
525 * is increased by one between each call, but that should not matter
526 * for this application.
528 static int get_prn(int count) {
529 count = count * 1103515245 + 12345;
530 return ((unsigned)(count/65536) % PRN_MODULO);
534 * Custom integer square root from
535 * http://en.wikipedia.org/wiki/Integer_square_root
537 static int sqrti(int val)
539 float d, x = val;
541 if (val == 0)
542 return 0;
544 do {
545 float y = (x + (float)val / x) / 2;
546 d = (y > x) ? y - x : x - y;
547 x = y;
548 } while (d >= 0.5);
550 return (int)x;
553 static struct commit_list *skip_away(struct commit_list *list, int count)
555 struct commit_list *cur, *previous;
556 int prn, index, i;
558 prn = get_prn(count);
559 index = (count * prn / PRN_MODULO) * sqrti(prn) / sqrti(PRN_MODULO);
561 cur = list;
562 previous = NULL;
564 for (i = 0; cur; cur = cur->next, i++) {
565 if (i == index) {
566 if (hashcmp(cur->item->object.sha1, current_bad_sha1))
567 return cur;
568 if (previous)
569 return previous;
570 return list;
572 previous = cur;
575 return list;
578 static struct commit_list *managed_skipped(struct commit_list *list,
579 struct commit_list **tried)
581 int count, skipped_first;
583 *tried = NULL;
585 if (!skipped_revs.nr)
586 return list;
588 list = filter_skipped(list, tried, 0, &count, &skipped_first);
590 if (!skipped_first)
591 return list;
593 return skip_away(list, count);
596 static void bisect_rev_setup(struct rev_info *revs, const char *prefix,
597 const char *bad_format, const char *good_format,
598 int read_paths)
600 struct argv_array rev_argv = ARGV_ARRAY_INIT;
601 int i;
603 init_revisions(revs, prefix);
604 revs->abbrev = 0;
605 revs->commit_format = CMIT_FMT_UNSPECIFIED;
607 /* rev_argv.argv[0] will be ignored by setup_revisions */
608 argv_array_push(&rev_argv, "bisect_rev_setup");
609 argv_array_pushf(&rev_argv, bad_format, sha1_to_hex(current_bad_sha1));
610 for (i = 0; i < good_revs.nr; i++)
611 argv_array_pushf(&rev_argv, good_format,
612 sha1_to_hex(good_revs.sha1[i]));
613 argv_array_push(&rev_argv, "--");
614 if (read_paths)
615 read_bisect_paths(&rev_argv);
617 setup_revisions(rev_argv.argc, rev_argv.argv, revs, NULL);
618 /* XXX leak rev_argv, as "revs" may still be pointing to it */
621 static void bisect_common(struct rev_info *revs)
623 if (prepare_revision_walk(revs))
624 die("revision walk setup failed");
625 if (revs->tree_objects)
626 mark_edges_uninteresting(revs->commits, revs, NULL);
629 static void exit_if_skipped_commits(struct commit_list *tried,
630 const unsigned char *bad)
632 if (!tried)
633 return;
635 printf("There are only 'skip'ped commits left to test.\n"
636 "The first bad commit could be any of:\n");
637 print_commit_list(tried, "%s\n", "%s\n");
638 if (bad)
639 printf("%s\n", sha1_to_hex(bad));
640 printf("We cannot bisect more!\n");
641 exit(2);
644 static int is_expected_rev(const unsigned char *sha1)
646 const char *filename = git_path("BISECT_EXPECTED_REV");
647 struct stat st;
648 struct strbuf str = STRBUF_INIT;
649 FILE *fp;
650 int res = 0;
652 if (stat(filename, &st) || !S_ISREG(st.st_mode))
653 return 0;
655 fp = fopen(filename, "r");
656 if (!fp)
657 return 0;
659 if (strbuf_getline(&str, fp, '\n') != EOF)
660 res = !strcmp(str.buf, sha1_to_hex(sha1));
662 strbuf_release(&str);
663 fclose(fp);
665 return res;
668 static void mark_expected_rev(char *bisect_rev_hex)
670 int len = strlen(bisect_rev_hex);
671 const char *filename = git_path("BISECT_EXPECTED_REV");
672 int fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
674 if (fd < 0)
675 die_errno("could not create file '%s'", filename);
677 bisect_rev_hex[len] = '\n';
678 write_or_die(fd, bisect_rev_hex, len + 1);
679 bisect_rev_hex[len] = '\0';
681 if (close(fd) < 0)
682 die("closing file %s: %s", filename, strerror(errno));
685 static int bisect_checkout(char *bisect_rev_hex, int no_checkout)
687 int res;
689 mark_expected_rev(bisect_rev_hex);
691 argv_checkout[2] = bisect_rev_hex;
692 if (no_checkout) {
693 argv_update_ref[3] = bisect_rev_hex;
694 if (run_command_v_opt(argv_update_ref, RUN_GIT_CMD))
695 die("update-ref --no-deref HEAD failed on %s",
696 bisect_rev_hex);
697 } else {
698 res = run_command_v_opt(argv_checkout, RUN_GIT_CMD);
699 if (res)
700 exit(res);
703 argv_show_branch[1] = bisect_rev_hex;
704 return run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
707 static struct commit *get_commit_reference(const unsigned char *sha1)
709 struct commit *r = lookup_commit_reference(sha1);
710 if (!r)
711 die("Not a valid commit name %s", sha1_to_hex(sha1));
712 return r;
715 static struct commit **get_bad_and_good_commits(int *rev_nr)
717 int len = 1 + good_revs.nr;
718 struct commit **rev = xmalloc(len * sizeof(*rev));
719 int i, n = 0;
721 rev[n++] = get_commit_reference(current_bad_sha1);
722 for (i = 0; i < good_revs.nr; i++)
723 rev[n++] = get_commit_reference(good_revs.sha1[i]);
724 *rev_nr = n;
726 return rev;
729 static void handle_bad_merge_base(void)
731 if (is_expected_rev(current_bad_sha1)) {
732 char *bad_hex = sha1_to_hex(current_bad_sha1);
733 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
735 fprintf(stderr, "The merge base %s is bad.\n"
736 "This means the bug has been fixed "
737 "between %s and [%s].\n",
738 bad_hex, bad_hex, good_hex);
740 exit(3);
743 fprintf(stderr, "Some good revs are not ancestor of the bad rev.\n"
744 "git bisect cannot work properly in this case.\n"
745 "Maybe you mistake good and bad revs?\n");
746 exit(1);
749 static void handle_skipped_merge_base(const unsigned char *mb)
751 char *mb_hex = sha1_to_hex(mb);
752 char *bad_hex = sha1_to_hex(current_bad_sha1);
753 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
755 warning("the merge base between %s and [%s] "
756 "must be skipped.\n"
757 "So we cannot be sure the first bad commit is "
758 "between %s and %s.\n"
759 "We continue anyway.",
760 bad_hex, good_hex, mb_hex, bad_hex);
761 free(good_hex);
765 * "check_merge_bases" checks that merge bases are not "bad".
767 * - If one is "bad", it means the user assumed something wrong
768 * and we must exit with a non 0 error code.
769 * - If one is "good", that's good, we have nothing to do.
770 * - If one is "skipped", we can't know but we should warn.
771 * - If we don't know, we should check it out and ask the user to test.
773 static void check_merge_bases(int no_checkout)
775 struct commit_list *result;
776 int rev_nr;
777 struct commit **rev = get_bad_and_good_commits(&rev_nr);
779 result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1, 0);
781 for (; result; result = result->next) {
782 const unsigned char *mb = result->item->object.sha1;
783 if (!hashcmp(mb, current_bad_sha1)) {
784 handle_bad_merge_base();
785 } else if (0 <= sha1_array_lookup(&good_revs, mb)) {
786 continue;
787 } else if (0 <= sha1_array_lookup(&skipped_revs, mb)) {
788 handle_skipped_merge_base(mb);
789 } else {
790 printf("Bisecting: a merge base must be tested\n");
791 exit(bisect_checkout(sha1_to_hex(mb), no_checkout));
795 free(rev);
796 free_commit_list(result);
799 static int check_ancestors(const char *prefix)
801 struct rev_info revs;
802 struct object_array pending_copy;
803 int res;
805 bisect_rev_setup(&revs, prefix, "^%s", "%s", 0);
807 /* Save pending objects, so they can be cleaned up later. */
808 pending_copy = revs.pending;
809 revs.leak_pending = 1;
812 * bisect_common calls prepare_revision_walk right away, which
813 * (together with .leak_pending = 1) makes us the sole owner of
814 * the list of pending objects.
816 bisect_common(&revs);
817 res = (revs.commits != NULL);
819 /* Clean up objects used, as they will be reused. */
820 clear_commit_marks_for_object_array(&pending_copy, ALL_REV_FLAGS);
821 free(pending_copy.objects);
823 return res;
827 * "check_good_are_ancestors_of_bad" checks that all "good" revs are
828 * ancestor of the "bad" rev.
830 * If that's not the case, we need to check the merge bases.
831 * If a merge base must be tested by the user, its source code will be
832 * checked out to be tested by the user and we will exit.
834 static void check_good_are_ancestors_of_bad(const char *prefix, int no_checkout)
836 char *filename = git_pathdup("BISECT_ANCESTORS_OK");
837 struct stat st;
838 int fd;
840 if (!current_bad_sha1)
841 die("a bad revision is needed");
843 /* Check if file BISECT_ANCESTORS_OK exists. */
844 if (!stat(filename, &st) && S_ISREG(st.st_mode))
845 goto done;
847 /* Bisecting with no good rev is ok. */
848 if (good_revs.nr == 0)
849 goto done;
851 /* Check if all good revs are ancestor of the bad rev. */
852 if (check_ancestors(prefix))
853 check_merge_bases(no_checkout);
855 /* Create file BISECT_ANCESTORS_OK. */
856 fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
857 if (fd < 0)
858 warning("could not create file '%s': %s",
859 filename, strerror(errno));
860 else
861 close(fd);
862 done:
863 free(filename);
867 * This does "git diff-tree --pretty COMMIT" without one fork+exec.
869 static void show_diff_tree(const char *prefix, struct commit *commit)
871 struct rev_info opt;
873 /* diff-tree init */
874 init_revisions(&opt, prefix);
875 git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
876 opt.abbrev = 0;
877 opt.diff = 1;
879 /* This is what "--pretty" does */
880 opt.verbose_header = 1;
881 opt.use_terminator = 0;
882 opt.commit_format = CMIT_FMT_DEFAULT;
884 /* diff-tree init */
885 if (!opt.diffopt.output_format)
886 opt.diffopt.output_format = DIFF_FORMAT_RAW;
888 log_tree_commit(&opt, commit);
892 * We use the convention that exiting with an exit code 10 means that
893 * the bisection process finished successfully.
894 * In this case the calling shell script should exit 0.
896 * If no_checkout is non-zero, the bisection process does not
897 * checkout the trial commit but instead simply updates BISECT_HEAD.
899 int bisect_next_all(const char *prefix, int no_checkout)
901 struct rev_info revs;
902 struct commit_list *tried;
903 int reaches = 0, all = 0, nr, steps;
904 const unsigned char *bisect_rev;
905 char bisect_rev_hex[41];
907 if (read_bisect_refs())
908 die("reading bisect refs failed");
910 check_good_are_ancestors_of_bad(prefix, no_checkout);
912 bisect_rev_setup(&revs, prefix, "%s", "^%s", 1);
913 revs.limited = 1;
915 bisect_common(&revs);
917 revs.commits = find_bisection(revs.commits, &reaches, &all,
918 !!skipped_revs.nr);
919 revs.commits = managed_skipped(revs.commits, &tried);
921 if (!revs.commits) {
923 * We should exit here only if the "bad"
924 * commit is also a "skip" commit.
926 exit_if_skipped_commits(tried, NULL);
928 printf("%s was both good and bad\n",
929 sha1_to_hex(current_bad_sha1));
930 exit(1);
933 if (!all) {
934 fprintf(stderr, "No testable commit found.\n"
935 "Maybe you started with bad path parameters?\n");
936 exit(4);
939 bisect_rev = revs.commits->item->object.sha1;
940 memcpy(bisect_rev_hex, sha1_to_hex(bisect_rev), 41);
942 if (!hashcmp(bisect_rev, current_bad_sha1)) {
943 exit_if_skipped_commits(tried, current_bad_sha1);
944 printf("%s is the first bad commit\n", bisect_rev_hex);
945 show_diff_tree(prefix, revs.commits->item);
946 /* This means the bisection process succeeded. */
947 exit(10);
950 nr = all - reaches - 1;
951 steps = estimate_bisect_steps(all);
952 printf("Bisecting: %d revision%s left to test after this "
953 "(roughly %d step%s)\n", nr, (nr == 1 ? "" : "s"),
954 steps, (steps == 1 ? "" : "s"));
956 return bisect_checkout(bisect_rev_hex, no_checkout);
959 static inline int log2i(int n)
961 int log2 = 0;
963 for (; n > 1; n >>= 1)
964 log2++;
966 return log2;
969 static inline int exp2i(int n)
971 return 1 << n;
975 * Estimate the number of bisect steps left (after the current step)
977 * For any x between 0 included and 2^n excluded, the probability for
978 * n - 1 steps left looks like:
980 * P(2^n + x) == (2^n - x) / (2^n + x)
982 * and P(2^n + x) < 0.5 means 2^n < 3x
984 int estimate_bisect_steps(int all)
986 int n, x, e;
988 if (all < 3)
989 return 0;
991 n = log2i(all);
992 e = exp2i(n);
993 x = all - e;
995 return (e < 3 * x) ? n : n - 1;