Merge branch 'master' of github.com:git/git
[alt-git.git] / bisect.c
blob8d5f8e58851ea650224c8de043891ea0de4a77cd
1 #include "git-compat-util.h"
2 #include "config.h"
3 #include "commit.h"
4 #include "diff.h"
5 #include "environment.h"
6 #include "gettext.h"
7 #include "hex.h"
8 #include "revision.h"
9 #include "refs.h"
10 #include "list-objects.h"
11 #include "quote.h"
12 #include "hash-lookup.h"
13 #include "run-command.h"
14 #include "log-tree.h"
15 #include "bisect.h"
16 #include "oid-array.h"
17 #include "strvec.h"
18 #include "commit-slab.h"
19 #include "commit-reach.h"
20 #include "object-name.h"
21 #include "object-store.h"
22 #include "dir.h"
24 static struct oid_array good_revs;
25 static struct oid_array skipped_revs;
27 static struct object_id *current_bad_oid;
29 static const char *term_bad;
30 static const char *term_good;
32 /* Remember to update object flag allocation in object.h */
33 #define COUNTED (1u<<16)
36 * This is a truly stupid algorithm, but it's only
37 * used for bisection, and we just don't care enough.
39 * We care just barely enough to avoid recursing for
40 * non-merge entries.
42 static int count_distance(struct commit_list *entry)
44 int nr = 0;
46 while (entry) {
47 struct commit *commit = entry->item;
48 struct commit_list *p;
50 if (commit->object.flags & (UNINTERESTING | COUNTED))
51 break;
52 if (!(commit->object.flags & TREESAME))
53 nr++;
54 commit->object.flags |= COUNTED;
55 p = commit->parents;
56 entry = p;
57 if (p) {
58 p = p->next;
59 while (p) {
60 nr += count_distance(p);
61 p = p->next;
66 return nr;
69 static void clear_distance(struct commit_list *list)
71 while (list) {
72 struct commit *commit = list->item;
73 commit->object.flags &= ~COUNTED;
74 list = list->next;
78 define_commit_slab(commit_weight, int *);
79 static struct commit_weight commit_weight;
81 #define DEBUG_BISECT 0
83 static inline int weight(struct commit_list *elem)
85 return **commit_weight_at(&commit_weight, elem->item);
88 static inline void weight_set(struct commit_list *elem, int weight)
90 **commit_weight_at(&commit_weight, elem->item) = weight;
93 static int count_interesting_parents(struct commit *commit, unsigned bisect_flags)
95 struct commit_list *p;
96 int count;
98 for (count = 0, p = commit->parents; p; p = p->next) {
99 if (!(p->item->object.flags & UNINTERESTING))
100 count++;
101 if (bisect_flags & FIND_BISECTION_FIRST_PARENT_ONLY)
102 break;
104 return count;
107 static inline int approx_halfway(struct commit_list *p, int nr)
109 int diff;
112 * Don't short-cut something we are not going to return!
114 if (p->item->object.flags & TREESAME)
115 return 0;
116 if (DEBUG_BISECT)
117 return 0;
119 * For small number of commits 2 and 3 are halfway of 5, and
120 * 3 is halfway of 6 but 2 and 4 are not.
122 diff = 2 * weight(p) - nr;
123 switch (diff) {
124 case -1: case 0: case 1:
125 return 1;
126 default:
128 * For large number of commits we are not so strict, it's
129 * good enough if it's within ~0.1% of the halfway point,
130 * e.g. 5000 is exactly halfway of 10000, but we consider
131 * the values [4996, 5004] as halfway as well.
133 if (abs(diff) < nr / 1024)
134 return 1;
135 return 0;
139 static void show_list(const char *debug, int counted, int nr,
140 struct commit_list *list)
142 struct commit_list *p;
144 if (!DEBUG_BISECT)
145 return;
147 fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr);
149 for (p = list; p; p = p->next) {
150 struct commit_list *pp;
151 struct commit *commit = p->item;
152 unsigned commit_flags = commit->object.flags;
153 enum object_type type;
154 unsigned long size;
155 char *buf = repo_read_object_file(the_repository,
156 &commit->object.oid, &type,
157 &size);
158 const char *subject_start;
159 int subject_len;
161 fprintf(stderr, "%c%c%c ",
162 (commit_flags & TREESAME) ? ' ' : 'T',
163 (commit_flags & UNINTERESTING) ? 'U' : ' ',
164 (commit_flags & COUNTED) ? 'C' : ' ');
165 if (*commit_weight_at(&commit_weight, p->item))
166 fprintf(stderr, "%3d", weight(p));
167 else
168 fprintf(stderr, "---");
169 fprintf(stderr, " %.*s", 8, oid_to_hex(&commit->object.oid));
170 for (pp = commit->parents; pp; pp = pp->next)
171 fprintf(stderr, " %.*s", 8,
172 oid_to_hex(&pp->item->object.oid));
174 subject_len = find_commit_subject(buf, &subject_start);
175 if (subject_len)
176 fprintf(stderr, " %.*s", subject_len, subject_start);
177 fprintf(stderr, "\n");
181 static struct commit_list *best_bisection(struct commit_list *list, int nr)
183 struct commit_list *p, *best;
184 int best_distance = -1;
186 best = list;
187 for (p = list; p; p = p->next) {
188 int distance;
189 unsigned commit_flags = p->item->object.flags;
191 if (commit_flags & TREESAME)
192 continue;
193 distance = weight(p);
194 if (nr - distance < distance)
195 distance = nr - distance;
196 if (distance > best_distance) {
197 best = p;
198 best_distance = distance;
202 return best;
205 struct commit_dist {
206 struct commit *commit;
207 int distance;
210 static int compare_commit_dist(const void *a_, const void *b_)
212 struct commit_dist *a, *b;
214 a = (struct commit_dist *)a_;
215 b = (struct commit_dist *)b_;
216 if (a->distance != b->distance)
217 return b->distance - a->distance; /* desc sort */
218 return oidcmp(&a->commit->object.oid, &b->commit->object.oid);
221 static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
223 struct commit_list *p;
224 struct commit_dist *array = xcalloc(nr, sizeof(*array));
225 struct strbuf buf = STRBUF_INIT;
226 int cnt, i;
228 for (p = list, cnt = 0; p; p = p->next) {
229 int distance;
230 unsigned commit_flags = p->item->object.flags;
232 if (commit_flags & TREESAME)
233 continue;
234 distance = weight(p);
235 if (nr - distance < distance)
236 distance = nr - distance;
237 array[cnt].commit = p->item;
238 array[cnt].distance = distance;
239 cnt++;
241 QSORT(array, cnt, compare_commit_dist);
242 for (p = list, i = 0; i < cnt; i++) {
243 struct object *obj = &(array[i].commit->object);
245 strbuf_reset(&buf);
246 strbuf_addf(&buf, "dist=%d", array[i].distance);
247 add_name_decoration(DECORATION_NONE, buf.buf, obj);
249 p->item = array[i].commit;
250 if (i < cnt - 1)
251 p = p->next;
253 if (p) {
254 free_commit_list(p->next);
255 p->next = NULL;
257 strbuf_release(&buf);
258 free(array);
259 return list;
263 * zero or positive weight is the number of interesting commits it can
264 * reach, including itself. Especially, weight = 0 means it does not
265 * reach any tree-changing commits (e.g. just above uninteresting one
266 * but traversal is with pathspec).
268 * weight = -1 means it has one parent and its distance is yet to
269 * be computed.
271 * weight = -2 means it has more than one parent and its distance is
272 * unknown. After running count_distance() first, they will get zero
273 * or positive distance.
275 static struct commit_list *do_find_bisection(struct commit_list *list,
276 int nr, int *weights,
277 unsigned bisect_flags)
279 int n, counted;
280 struct commit_list *p;
282 counted = 0;
284 for (n = 0, p = list; p; p = p->next) {
285 struct commit *commit = p->item;
286 unsigned commit_flags = commit->object.flags;
288 *commit_weight_at(&commit_weight, p->item) = &weights[n++];
289 switch (count_interesting_parents(commit, bisect_flags)) {
290 case 0:
291 if (!(commit_flags & TREESAME)) {
292 weight_set(p, 1);
293 counted++;
294 show_list("bisection 2 count one",
295 counted, nr, list);
298 * otherwise, it is known not to reach any
299 * tree-changing commit and gets weight 0.
301 break;
302 case 1:
303 weight_set(p, -1);
304 break;
305 default:
306 weight_set(p, -2);
307 break;
311 show_list("bisection 2 initialize", counted, nr, list);
314 * If you have only one parent in the resulting set
315 * then you can reach one commit more than that parent
316 * can reach. So we do not have to run the expensive
317 * count_distance() for single strand of pearls.
319 * However, if you have more than one parents, you cannot
320 * just add their distance and one for yourself, since
321 * they usually reach the same ancestor and you would
322 * end up counting them twice that way.
324 * So we will first count distance of merges the usual
325 * way, and then fill the blanks using cheaper algorithm.
327 for (p = list; p; p = p->next) {
328 if (p->item->object.flags & UNINTERESTING)
329 continue;
330 if (weight(p) != -2)
331 continue;
332 if (bisect_flags & FIND_BISECTION_FIRST_PARENT_ONLY)
333 BUG("shouldn't be calling count-distance in fp mode");
334 weight_set(p, count_distance(p));
335 clear_distance(list);
337 /* Does it happen to be at half-way? */
338 if (!(bisect_flags & FIND_BISECTION_ALL) &&
339 approx_halfway(p, nr))
340 return p;
341 counted++;
344 show_list("bisection 2 count_distance", counted, nr, list);
346 while (counted < nr) {
347 for (p = list; p; p = p->next) {
348 struct commit_list *q;
349 unsigned commit_flags = p->item->object.flags;
351 if (0 <= weight(p))
352 continue;
354 for (q = p->item->parents;
356 q = bisect_flags & FIND_BISECTION_FIRST_PARENT_ONLY ? NULL : q->next) {
357 if (q->item->object.flags & UNINTERESTING)
358 continue;
359 if (0 <= weight(q))
360 break;
362 if (!q)
363 continue;
366 * weight for p is unknown but q is known.
367 * add one for p itself if p is to be counted,
368 * otherwise inherit it from q directly.
370 if (!(commit_flags & TREESAME)) {
371 weight_set(p, weight(q)+1);
372 counted++;
373 show_list("bisection 2 count one",
374 counted, nr, list);
376 else
377 weight_set(p, weight(q));
379 /* Does it happen to be at half-way? */
380 if (!(bisect_flags & FIND_BISECTION_ALL) &&
381 approx_halfway(p, nr))
382 return p;
386 show_list("bisection 2 counted all", counted, nr, list);
388 if (!(bisect_flags & FIND_BISECTION_ALL))
389 return best_bisection(list, nr);
390 else
391 return best_bisection_sorted(list, nr);
394 void find_bisection(struct commit_list **commit_list, int *reaches,
395 int *all, unsigned bisect_flags)
397 int nr, on_list;
398 struct commit_list *list, *p, *best, *next, *last;
399 int *weights;
401 show_list("bisection 2 entry", 0, 0, *commit_list);
402 init_commit_weight(&commit_weight);
405 * Count the number of total and tree-changing items on the
406 * list, while reversing the list.
408 for (nr = on_list = 0, last = NULL, p = *commit_list;
410 p = next) {
411 unsigned commit_flags = p->item->object.flags;
413 next = p->next;
414 if (commit_flags & UNINTERESTING) {
415 free(p);
416 continue;
418 p->next = last;
419 last = p;
420 if (!(commit_flags & TREESAME))
421 nr++;
422 on_list++;
424 list = last;
425 show_list("bisection 2 sorted", 0, nr, list);
427 *all = nr;
428 CALLOC_ARRAY(weights, on_list);
430 /* Do the real work of finding bisection commit. */
431 best = do_find_bisection(list, nr, weights, bisect_flags);
432 if (best) {
433 if (!(bisect_flags & FIND_BISECTION_ALL)) {
434 list->item = best->item;
435 free_commit_list(list->next);
436 best = list;
437 best->next = NULL;
439 *reaches = weight(best);
441 free(weights);
442 *commit_list = best;
443 clear_commit_weight(&commit_weight);
446 static int register_ref(const char *refname, const struct object_id *oid,
447 int flags UNUSED, void *cb_data UNUSED)
449 struct strbuf good_prefix = STRBUF_INIT;
450 strbuf_addstr(&good_prefix, term_good);
451 strbuf_addstr(&good_prefix, "-");
453 if (!strcmp(refname, term_bad)) {
454 current_bad_oid = xmalloc(sizeof(*current_bad_oid));
455 oidcpy(current_bad_oid, oid);
456 } else if (starts_with(refname, good_prefix.buf)) {
457 oid_array_append(&good_revs, oid);
458 } else if (starts_with(refname, "skip-")) {
459 oid_array_append(&skipped_revs, oid);
462 strbuf_release(&good_prefix);
464 return 0;
467 static int read_bisect_refs(void)
469 return for_each_ref_in("refs/bisect/", register_ref, NULL);
472 static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
473 static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")
474 static GIT_PATH_FUNC(git_path_bisect_ancestors_ok, "BISECT_ANCESTORS_OK")
475 static GIT_PATH_FUNC(git_path_bisect_run, "BISECT_RUN")
476 static GIT_PATH_FUNC(git_path_bisect_start, "BISECT_START")
477 static GIT_PATH_FUNC(git_path_bisect_log, "BISECT_LOG")
478 static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
479 static GIT_PATH_FUNC(git_path_bisect_first_parent, "BISECT_FIRST_PARENT")
481 static void read_bisect_paths(struct strvec *array)
483 struct strbuf str = STRBUF_INIT;
484 const char *filename = git_path_bisect_names();
485 FILE *fp = xfopen(filename, "r");
487 while (strbuf_getline_lf(&str, fp) != EOF) {
488 strbuf_trim(&str);
489 if (sq_dequote_to_strvec(str.buf, array))
490 die(_("Badly quoted content in file '%s': %s"),
491 filename, str.buf);
494 strbuf_release(&str);
495 fclose(fp);
498 static char *join_oid_array_hex(struct oid_array *array, char delim)
500 struct strbuf joined_hexs = STRBUF_INIT;
501 int i;
503 for (i = 0; i < array->nr; i++) {
504 strbuf_addstr(&joined_hexs, oid_to_hex(array->oid + i));
505 if (i + 1 < array->nr)
506 strbuf_addch(&joined_hexs, delim);
509 return strbuf_detach(&joined_hexs, NULL);
513 * In this function, passing a not NULL skipped_first is very special.
514 * It means that we want to know if the first commit in the list is
515 * skipped because we will want to test a commit away from it if it is
516 * indeed skipped.
517 * So if the first commit is skipped, we cannot take the shortcut to
518 * just "return list" when we find the first non skipped commit, we
519 * have to return a fully filtered list.
521 * We use (*skipped_first == -1) to mean "it has been found that the
522 * first commit is not skipped". In this case *skipped_first is set back
523 * to 0 just before the function returns.
525 struct commit_list *filter_skipped(struct commit_list *list,
526 struct commit_list **tried,
527 int show_all,
528 int *count,
529 int *skipped_first)
531 struct commit_list *filtered = NULL, **f = &filtered;
533 *tried = NULL;
535 if (skipped_first)
536 *skipped_first = 0;
537 if (count)
538 *count = 0;
540 if (!skipped_revs.nr)
541 return list;
543 while (list) {
544 struct commit_list *next = list->next;
545 list->next = NULL;
546 if (0 <= oid_array_lookup(&skipped_revs, &list->item->object.oid)) {
547 if (skipped_first && !*skipped_first)
548 *skipped_first = 1;
549 /* Move current to tried list */
550 *tried = list;
551 tried = &list->next;
552 } else {
553 if (!show_all) {
554 if (!skipped_first || !*skipped_first)
555 return list;
556 } else if (skipped_first && !*skipped_first) {
557 /* This means we know it's not skipped */
558 *skipped_first = -1;
560 /* Move current to filtered list */
561 *f = list;
562 f = &list->next;
563 if (count)
564 (*count)++;
566 list = next;
569 if (skipped_first && *skipped_first == -1)
570 *skipped_first = 0;
572 return filtered;
575 #define PRN_MODULO 32768
578 * This is a pseudo random number generator based on "man 3 rand".
579 * It is not used properly because the seed is the argument and it
580 * is increased by one between each call, but that should not matter
581 * for this application.
583 static unsigned get_prn(unsigned count)
585 count = count * 1103515245 + 12345;
586 return (count/65536) % PRN_MODULO;
590 * Custom integer square root from
591 * https://en.wikipedia.org/wiki/Integer_square_root
593 static int sqrti(int val)
595 float d, x = val;
597 if (!val)
598 return 0;
600 do {
601 float y = (x + (float)val / x) / 2;
602 d = (y > x) ? y - x : x - y;
603 x = y;
604 } while (d >= 0.5);
606 return (int)x;
609 static struct commit_list *skip_away(struct commit_list *list, int count)
611 struct commit_list *cur, *previous;
612 int prn, index, i;
614 prn = get_prn(count);
615 index = (count * prn / PRN_MODULO) * sqrti(prn) / sqrti(PRN_MODULO);
617 cur = list;
618 previous = NULL;
620 for (i = 0; cur; cur = cur->next, i++) {
621 if (i == index) {
622 if (!oideq(&cur->item->object.oid, current_bad_oid))
623 return cur;
624 if (previous)
625 return previous;
626 return list;
628 previous = cur;
631 return list;
634 static struct commit_list *managed_skipped(struct commit_list *list,
635 struct commit_list **tried)
637 int count, skipped_first;
639 *tried = NULL;
641 if (!skipped_revs.nr)
642 return list;
644 list = filter_skipped(list, tried, 0, &count, &skipped_first);
646 if (!skipped_first)
647 return list;
649 return skip_away(list, count);
652 static void bisect_rev_setup(struct repository *r, struct rev_info *revs,
653 struct strvec *rev_argv,
654 const char *prefix,
655 const char *bad_format, const char *good_format,
656 int read_paths)
658 struct setup_revision_opt opt = {
659 .free_removed_argv_elements = 1,
661 int i;
663 repo_init_revisions(r, revs, prefix);
664 revs->abbrev = 0;
665 revs->commit_format = CMIT_FMT_UNSPECIFIED;
667 /* rev_argv.argv[0] will be ignored by setup_revisions */
668 strvec_push(rev_argv, "bisect_rev_setup");
669 strvec_pushf(rev_argv, bad_format, oid_to_hex(current_bad_oid));
670 for (i = 0; i < good_revs.nr; i++)
671 strvec_pushf(rev_argv, good_format,
672 oid_to_hex(good_revs.oid + i));
673 strvec_push(rev_argv, "--");
674 if (read_paths)
675 read_bisect_paths(rev_argv);
677 setup_revisions(rev_argv->nr, rev_argv->v, revs, &opt);
680 static void bisect_common(struct rev_info *revs)
682 if (prepare_revision_walk(revs))
683 die("revision walk setup failed");
684 if (revs->tree_objects)
685 mark_edges_uninteresting(revs, NULL, 0);
688 static enum bisect_error error_if_skipped_commits(struct commit_list *tried,
689 const struct object_id *bad)
691 if (!tried)
692 return BISECT_OK;
694 printf("There are only 'skip'ped commits left to test.\n"
695 "The first %s commit could be any of:\n", term_bad);
697 for ( ; tried; tried = tried->next)
698 printf("%s\n", oid_to_hex(&tried->item->object.oid));
700 if (bad)
701 printf("%s\n", oid_to_hex(bad));
702 printf(_("We cannot bisect more!\n"));
704 return BISECT_ONLY_SKIPPED_LEFT;
707 static int is_expected_rev(const struct object_id *oid)
709 const char *filename = git_path_bisect_expected_rev();
710 struct stat st;
711 struct strbuf str = STRBUF_INIT;
712 FILE *fp;
713 int res = 0;
715 if (stat(filename, &st) || !S_ISREG(st.st_mode))
716 return 0;
718 fp = fopen_or_warn(filename, "r");
719 if (!fp)
720 return 0;
722 if (strbuf_getline_lf(&str, fp) != EOF)
723 res = !strcmp(str.buf, oid_to_hex(oid));
725 strbuf_release(&str);
726 fclose(fp);
728 return res;
731 enum bisect_error bisect_checkout(const struct object_id *bisect_rev,
732 int no_checkout)
734 struct commit *commit;
735 struct pretty_print_context pp = {0};
736 struct strbuf commit_msg = STRBUF_INIT;
738 update_ref(NULL, "BISECT_EXPECTED_REV", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
740 if (no_checkout) {
741 update_ref(NULL, "BISECT_HEAD", bisect_rev, NULL, 0,
742 UPDATE_REFS_DIE_ON_ERR);
743 } else {
744 struct child_process cmd = CHILD_PROCESS_INIT;
746 cmd.git_cmd = 1;
747 strvec_pushl(&cmd.args, "checkout", "-q",
748 oid_to_hex(bisect_rev), "--", NULL);
749 if (run_command(&cmd))
751 * Errors in `run_command()` itself, signaled by res < 0,
752 * and errors in the child process, signaled by res > 0
753 * can both be treated as regular BISECT_FAILED (-1).
755 return BISECT_FAILED;
758 commit = lookup_commit_reference(the_repository, bisect_rev);
759 repo_format_commit_message(the_repository, commit, "[%H] %s%n",
760 &commit_msg, &pp);
761 fputs(commit_msg.buf, stdout);
762 strbuf_release(&commit_msg);
764 return BISECT_OK;
767 static struct commit *get_commit_reference(struct repository *r,
768 const struct object_id *oid)
770 struct commit *c = lookup_commit_reference(r, oid);
771 if (!c)
772 die(_("Not a valid commit name %s"), oid_to_hex(oid));
773 return c;
776 static struct commit **get_bad_and_good_commits(struct repository *r,
777 int *rev_nr)
779 struct commit **rev;
780 int i, n = 0;
782 ALLOC_ARRAY(rev, 1 + good_revs.nr);
783 rev[n++] = get_commit_reference(r, current_bad_oid);
784 for (i = 0; i < good_revs.nr; i++)
785 rev[n++] = get_commit_reference(r, good_revs.oid + i);
786 *rev_nr = n;
788 return rev;
791 static enum bisect_error handle_bad_merge_base(void)
793 if (is_expected_rev(current_bad_oid)) {
794 char *bad_hex = oid_to_hex(current_bad_oid);
795 char *good_hex = join_oid_array_hex(&good_revs, ' ');
796 if (!strcmp(term_bad, "bad") && !strcmp(term_good, "good")) {
797 fprintf(stderr, _("The merge base %s is bad.\n"
798 "This means the bug has been fixed "
799 "between %s and [%s].\n"),
800 bad_hex, bad_hex, good_hex);
801 } else if (!strcmp(term_bad, "new") && !strcmp(term_good, "old")) {
802 fprintf(stderr, _("The merge base %s is new.\n"
803 "The property has changed "
804 "between %s and [%s].\n"),
805 bad_hex, bad_hex, good_hex);
806 } else {
807 fprintf(stderr, _("The merge base %s is %s.\n"
808 "This means the first '%s' commit is "
809 "between %s and [%s].\n"),
810 bad_hex, term_bad, term_good, bad_hex, good_hex);
812 return BISECT_MERGE_BASE_CHECK;
815 fprintf(stderr, _("Some %s revs are not ancestors of the %s rev.\n"
816 "git bisect cannot work properly in this case.\n"
817 "Maybe you mistook %s and %s revs?\n"),
818 term_good, term_bad, term_good, term_bad);
819 return BISECT_FAILED;
822 static void handle_skipped_merge_base(const struct object_id *mb)
824 char *mb_hex = oid_to_hex(mb);
825 char *bad_hex = oid_to_hex(current_bad_oid);
826 char *good_hex = join_oid_array_hex(&good_revs, ' ');
828 warning(_("the merge base between %s and [%s] "
829 "must be skipped.\n"
830 "So we cannot be sure the first %s commit is "
831 "between %s and %s.\n"
832 "We continue anyway."),
833 bad_hex, good_hex, term_bad, mb_hex, bad_hex);
834 free(good_hex);
838 * "check_merge_bases" checks that merge bases are not "bad" (or "new").
840 * - If one is "bad" (or "new"), it means the user assumed something wrong
841 * and we must return error with a non 0 error code.
842 * - If one is "good" (or "old"), that's good, we have nothing to do.
843 * - If one is "skipped", we can't know but we should warn.
844 * - If we don't know, we should check it out and ask the user to test.
845 * - If a merge base must be tested, on success return
846 * BISECT_INTERNAL_SUCCESS_MERGE_BASE (-11) a special condition
847 * for early success, this will be converted back to 0 in
848 * check_good_are_ancestors_of_bad().
850 static enum bisect_error check_merge_bases(int rev_nr, struct commit **rev, int no_checkout)
852 enum bisect_error res = BISECT_OK;
853 struct commit_list *result;
855 result = repo_get_merge_bases_many(the_repository, rev[0], rev_nr - 1,
856 rev + 1);
858 for (; result; result = result->next) {
859 const struct object_id *mb = &result->item->object.oid;
860 if (oideq(mb, current_bad_oid)) {
861 res = handle_bad_merge_base();
862 break;
863 } else if (0 <= oid_array_lookup(&good_revs, mb)) {
864 continue;
865 } else if (0 <= oid_array_lookup(&skipped_revs, mb)) {
866 handle_skipped_merge_base(mb);
867 } else {
868 printf(_("Bisecting: a merge base must be tested\n"));
869 res = bisect_checkout(mb, no_checkout);
870 if (!res)
871 /* indicate early success */
872 res = BISECT_INTERNAL_SUCCESS_MERGE_BASE;
873 break;
877 free_commit_list(result);
878 return res;
881 static int check_ancestors(struct repository *r, int rev_nr,
882 struct commit **rev, const char *prefix)
884 struct strvec rev_argv = STRVEC_INIT;
885 struct rev_info revs;
886 int res;
888 bisect_rev_setup(r, &revs, &rev_argv, prefix, "^%s", "%s", 0);
890 bisect_common(&revs);
891 res = (revs.commits != NULL);
893 /* Clean up objects used, as they will be reused. */
894 clear_commit_marks_many(rev_nr, rev, ALL_REV_FLAGS);
896 release_revisions(&revs);
897 strvec_clear(&rev_argv);
898 return res;
902 * "check_good_are_ancestors_of_bad" checks that all "good" revs are
903 * ancestor of the "bad" rev.
905 * If that's not the case, we need to check the merge bases.
906 * If a merge base must be tested by the user, its source code will be
907 * checked out to be tested by the user and we will return.
910 static enum bisect_error check_good_are_ancestors_of_bad(struct repository *r,
911 const char *prefix,
912 int no_checkout)
914 char *filename;
915 struct stat st;
916 int fd, rev_nr;
917 enum bisect_error res = BISECT_OK;
918 struct commit **rev;
920 if (!current_bad_oid)
921 return error(_("a %s revision is needed"), term_bad);
923 filename = git_pathdup("BISECT_ANCESTORS_OK");
925 /* Check if file BISECT_ANCESTORS_OK exists. */
926 if (!stat(filename, &st) && S_ISREG(st.st_mode))
927 goto done;
929 /* Bisecting with no good rev is ok. */
930 if (!good_revs.nr)
931 goto done;
933 /* Check if all good revs are ancestor of the bad rev. */
935 rev = get_bad_and_good_commits(r, &rev_nr);
936 if (check_ancestors(r, rev_nr, rev, prefix))
937 res = check_merge_bases(rev_nr, rev, no_checkout);
938 free(rev);
940 if (!res) {
941 /* Create file BISECT_ANCESTORS_OK. */
942 fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
943 if (fd < 0)
945 * BISECT_ANCESTORS_OK file is not absolutely necessary,
946 * the bisection process will continue at the next
947 * bisection step.
948 * So, just signal with a warning that something
949 * might be wrong.
951 warning_errno(_("could not create file '%s'"),
952 filename);
953 else
954 close(fd);
956 done:
957 free(filename);
958 return res;
962 * This does "git diff-tree --pretty COMMIT" without one fork+exec.
964 static void show_diff_tree(struct repository *r,
965 const char *prefix,
966 struct commit *commit)
968 const char *argv[] = {
969 "diff-tree", "--pretty", "--stat", "--summary", "--cc", NULL
971 struct rev_info opt;
973 git_config(git_diff_ui_config, NULL);
974 repo_init_revisions(r, &opt, prefix);
976 setup_revisions(ARRAY_SIZE(argv) - 1, argv, &opt, NULL);
977 log_tree_commit(&opt, commit);
978 release_revisions(&opt);
982 * The terms used for this bisect session are stored in BISECT_TERMS.
983 * We read them and store them to adapt the messages accordingly.
984 * Default is bad/good.
986 void read_bisect_terms(const char **read_bad, const char **read_good)
988 struct strbuf str = STRBUF_INIT;
989 const char *filename = git_path_bisect_terms();
990 FILE *fp = fopen(filename, "r");
992 if (!fp) {
993 if (errno == ENOENT) {
994 *read_bad = "bad";
995 *read_good = "good";
996 return;
997 } else {
998 die_errno(_("could not read file '%s'"), filename);
1000 } else {
1001 strbuf_getline_lf(&str, fp);
1002 *read_bad = strbuf_detach(&str, NULL);
1003 strbuf_getline_lf(&str, fp);
1004 *read_good = strbuf_detach(&str, NULL);
1006 strbuf_release(&str);
1007 fclose(fp);
1011 * We use the convention that return BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND (-10) means
1012 * the bisection process finished successfully.
1013 * In this case the calling function or command should not turn a
1014 * BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND return code into an error or a non zero exit code.
1016 * Checking BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND
1017 * in bisect_helper::bisect_next() and only transforming it to 0 at
1018 * the end of bisect_helper::cmd_bisect__helper() helps bypassing
1019 * all the code related to finding a commit to test.
1021 enum bisect_error bisect_next_all(struct repository *r, const char *prefix)
1023 struct strvec rev_argv = STRVEC_INIT;
1024 struct rev_info revs = REV_INFO_INIT;
1025 struct commit_list *tried;
1026 int reaches = 0, all = 0, nr, steps;
1027 enum bisect_error res = BISECT_OK;
1028 struct object_id *bisect_rev;
1029 char *steps_msg;
1031 * If no_checkout is non-zero, the bisection process does not
1032 * checkout the trial commit but instead simply updates BISECT_HEAD.
1034 int no_checkout = ref_exists("BISECT_HEAD");
1035 unsigned bisect_flags = 0;
1037 read_bisect_terms(&term_bad, &term_good);
1038 if (read_bisect_refs())
1039 die(_("reading bisect refs failed"));
1041 if (file_exists(git_path_bisect_first_parent()))
1042 bisect_flags |= FIND_BISECTION_FIRST_PARENT_ONLY;
1044 if (skipped_revs.nr)
1045 bisect_flags |= FIND_BISECTION_ALL;
1047 res = check_good_are_ancestors_of_bad(r, prefix, no_checkout);
1048 if (res)
1049 goto cleanup;
1051 bisect_rev_setup(r, &revs, &rev_argv, prefix, "%s", "^%s", 1);
1053 revs.first_parent_only = !!(bisect_flags & FIND_BISECTION_FIRST_PARENT_ONLY);
1054 revs.limited = 1;
1056 bisect_common(&revs);
1058 find_bisection(&revs.commits, &reaches, &all, bisect_flags);
1059 revs.commits = managed_skipped(revs.commits, &tried);
1061 if (!revs.commits) {
1063 * We should return error here only if the "bad"
1064 * commit is also a "skip" commit.
1066 res = error_if_skipped_commits(tried, NULL);
1067 if (res < 0)
1068 goto cleanup;
1069 printf(_("%s was both %s and %s\n"),
1070 oid_to_hex(current_bad_oid),
1071 term_good,
1072 term_bad);
1074 res = BISECT_FAILED;
1075 goto cleanup;
1078 if (!all) {
1079 fprintf(stderr, _("No testable commit found.\n"
1080 "Maybe you started with bad path arguments?\n"));
1082 res = BISECT_NO_TESTABLE_COMMIT;
1083 goto cleanup;
1086 bisect_rev = &revs.commits->item->object.oid;
1088 if (oideq(bisect_rev, current_bad_oid)) {
1089 res = error_if_skipped_commits(tried, current_bad_oid);
1090 if (res)
1091 return res;
1092 printf("%s is the first %s commit\n", oid_to_hex(bisect_rev),
1093 term_bad);
1095 show_diff_tree(r, prefix, revs.commits->item);
1097 * This means the bisection process succeeded.
1098 * Using BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND (-10)
1099 * so that the call chain can simply check
1100 * for negative return values for early returns up
1101 * until the cmd_bisect__helper() caller.
1103 res = BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND;
1104 goto cleanup;
1107 nr = all - reaches - 1;
1108 steps = estimate_bisect_steps(all);
1110 steps_msg = xstrfmt(Q_("(roughly %d step)", "(roughly %d steps)",
1111 steps), steps);
1113 * TRANSLATORS: the last %s will be replaced with "(roughly %d
1114 * steps)" translation.
1116 printf(Q_("Bisecting: %d revision left to test after this %s\n",
1117 "Bisecting: %d revisions left to test after this %s\n",
1118 nr), nr, steps_msg);
1119 free(steps_msg);
1120 /* Clean up objects used, as they will be reused. */
1121 repo_clear_commit_marks(r, ALL_REV_FLAGS);
1123 res = bisect_checkout(bisect_rev, no_checkout);
1124 cleanup:
1125 release_revisions(&revs);
1126 strvec_clear(&rev_argv);
1127 return res;
1130 static inline int log2i(int n)
1132 int log2 = 0;
1134 for (; n > 1; n >>= 1)
1135 log2++;
1137 return log2;
1140 static inline int exp2i(int n)
1142 return 1 << n;
1146 * Estimate the number of bisect steps left (after the current step)
1148 * For any x between 0 included and 2^n excluded, the probability for
1149 * n - 1 steps left looks like:
1151 * P(2^n + x) == (2^n - x) / (2^n + x)
1153 * and P(2^n + x) < 0.5 means 2^n < 3x
1155 int estimate_bisect_steps(int all)
1157 int n, x, e;
1159 if (all < 3)
1160 return 0;
1162 n = log2i(all);
1163 e = exp2i(n);
1164 x = all - e;
1166 return (e < 3 * x) ? n : n - 1;
1169 static int mark_for_removal(const char *refname,
1170 const struct object_id *oid UNUSED,
1171 int flag UNUSED, void *cb_data)
1173 struct string_list *refs = cb_data;
1174 char *ref = xstrfmt("refs/bisect%s", refname);
1175 string_list_append(refs, ref);
1176 return 0;
1179 int bisect_clean_state(void)
1181 int result = 0;
1183 /* There may be some refs packed during bisection */
1184 struct string_list refs_for_removal = STRING_LIST_INIT_NODUP;
1185 for_each_ref_in("refs/bisect", mark_for_removal, (void *) &refs_for_removal);
1186 string_list_append(&refs_for_removal, xstrdup("BISECT_HEAD"));
1187 result = delete_refs("bisect: remove", &refs_for_removal, REF_NO_DEREF);
1188 refs_for_removal.strdup_strings = 1;
1189 string_list_clear(&refs_for_removal, 0);
1190 unlink_or_warn(git_path_bisect_expected_rev());
1191 unlink_or_warn(git_path_bisect_ancestors_ok());
1192 unlink_or_warn(git_path_bisect_log());
1193 unlink_or_warn(git_path_bisect_names());
1194 unlink_or_warn(git_path_bisect_run());
1195 unlink_or_warn(git_path_bisect_terms());
1196 unlink_or_warn(git_path_bisect_first_parent());
1198 * Cleanup BISECT_START last to support the --no-checkout option
1199 * introduced in the commit 4796e823a.
1201 unlink_or_warn(git_path_bisect_start());
1203 return result;