doc: describe git svn init --ignore-refs
[git/git-svn.git] / bisect.c
blobc952df692bef9ba1638e55448050db33ba76d399
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 oid_array good_revs;
16 static struct oid_array skipped_revs;
18 static struct object_id *current_bad_oid;
20 static const char *argv_checkout[] = {"checkout", "-q", NULL, "--", NULL};
21 static const char *argv_show_branch[] = {"show-branch", NULL, NULL};
23 static const char *term_bad;
24 static const char *term_good;
26 /* Remember to update object flag allocation in object.h */
27 #define COUNTED (1u<<16)
30 * This is a truly stupid algorithm, but it's only
31 * used for bisection, and we just don't care enough.
33 * We care just barely enough to avoid recursing for
34 * non-merge entries.
36 static int count_distance(struct commit_list *entry)
38 int nr = 0;
40 while (entry) {
41 struct commit *commit = entry->item;
42 struct commit_list *p;
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;
60 return nr;
63 static void clear_distance(struct commit_list *list)
65 while (list) {
66 struct commit *commit = list->item;
67 commit->object.flags &= ~COUNTED;
68 list = list->next;
72 #define DEBUG_BISECT 0
74 static inline int weight(struct commit_list *elem)
76 return *((int*)(elem->item->util));
79 static inline void weight_set(struct commit_list *elem, int weight)
81 *((int*)(elem->item->util)) = weight;
84 static int count_interesting_parents(struct commit *commit)
86 struct commit_list *p;
87 int count;
89 for (count = 0, p = commit->parents; p; p = p->next) {
90 if (p->item->object.flags & UNINTERESTING)
91 continue;
92 count++;
94 return count;
97 static inline int halfway(struct commit_list *p, int nr)
100 * Don't short-cut something we are not going to return!
102 if (p->item->object.flags & TREESAME)
103 return 0;
104 if (DEBUG_BISECT)
105 return 0;
107 * 2 and 3 are halfway of 5.
108 * 3 is halfway of 6 but 2 and 4 are not.
110 switch (2 * weight(p) - nr) {
111 case -1: case 0: case 1:
112 return 1;
113 default:
114 return 0;
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)
124 struct commit_list *p;
126 fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr);
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;
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));
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");
157 #endif /* DEBUG_BISECT */
159 static struct commit_list *best_bisection(struct commit_list *list, int nr)
161 struct commit_list *p, *best;
162 int best_distance = -1;
164 best = list;
165 for (p = list; p; p = p->next) {
166 int distance;
167 unsigned flags = p->item->object.flags;
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;
180 return best;
183 struct commit_dist {
184 struct commit *commit;
185 int distance;
188 static int compare_commit_dist(const void *a_, const void *b_)
190 struct commit_dist *a, *b;
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);
199 static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
201 struct commit_list *p;
202 struct commit_dist *array = xcalloc(nr, sizeof(*array));
203 struct strbuf buf = STRBUF_INIT;
204 int cnt, i;
206 for (p = list, cnt = 0; p; p = p->next) {
207 int distance;
208 unsigned flags = p->item->object.flags;
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++;
219 QSORT(array, cnt, compare_commit_dist);
220 for (p = list, i = 0; i < cnt; i++) {
221 struct object *obj = &(array[i].commit->object);
223 strbuf_reset(&buf);
224 strbuf_addf(&buf, "dist=%d", array[i].distance);
225 add_name_decoration(DECORATION_NONE, buf.buf, obj);
227 p->item = array[i].commit;
228 p = p->next;
230 if (p)
231 p->next = NULL;
232 strbuf_release(&buf);
233 free(array);
234 return list;
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).
243 * weight = -1 means it has one parent and its distance is yet to
244 * be computed.
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.
250 static struct commit_list *do_find_bisection(struct commit_list *list,
251 int nr, int *weights,
252 int find_all)
254 int n, counted;
255 struct commit_list *p;
257 counted = 0;
259 for (n = 0, p = list; p; p = p->next) {
260 struct commit *commit = p->item;
261 unsigned flags = commit->object.flags;
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);
273 * otherwise, it is known not to reach any
274 * tree-changing commit and gets weight 0.
276 break;
277 case 1:
278 weight_set(p, -1);
279 break;
280 default:
281 weight_set(p, -2);
282 break;
286 show_list("bisection 2 initialize", counted, nr, list);
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.
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.
299 * So we will first count distance of merges the usual
300 * way, and then fill the blanks using cheaper algorithm.
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);
310 /* Does it happen to be at exactly half-way? */
311 if (!find_all && halfway(p, nr))
312 return p;
313 counted++;
316 show_list("bisection 2 count_distance", counted, nr, list);
318 while (counted < nr) {
319 for (p = list; p; p = p->next) {
320 struct commit_list *q;
321 unsigned flags = p->item->object.flags;
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;
331 if (!q)
332 continue;
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.
339 if (!(flags & TREESAME)) {
340 weight_set(p, weight(q)+1);
341 counted++;
342 show_list("bisection 2 count one",
343 counted, nr, list);
345 else
346 weight_set(p, weight(q));
348 /* Does it happen to be at exactly half-way? */
349 if (!find_all && halfway(p, nr))
350 return p;
354 show_list("bisection 2 counted all", counted, nr, list);
356 if (!find_all)
357 return best_bisection(list, nr);
358 else
359 return best_bisection_sorted(list, nr);
362 struct commit_list *find_bisection(struct commit_list *list,
363 int *reaches, int *all,
364 int find_all)
366 int nr, on_list;
367 struct commit_list *p, *best, *next, *last;
368 int *weights;
370 show_list("bisection 2 entry", 0, 0, list);
373 * Count the number of total and tree-changing items on the
374 * list, while reversing the list.
376 for (nr = on_list = 0, last = NULL, p = list;
378 p = next) {
379 unsigned flags = p->item->object.flags;
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++;
390 list = last;
391 show_list("bisection 2 sorted", 0, nr, list);
393 *all = nr;
394 weights = xcalloc(on_list, sizeof(*weights));
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);
403 free(weights);
404 return best;
407 static int register_ref(const char *refname, const struct object_id *oid,
408 int flags, void *cb_data)
410 struct strbuf good_prefix = STRBUF_INIT;
411 strbuf_addstr(&good_prefix, term_good);
412 strbuf_addstr(&good_prefix, "-");
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);
423 strbuf_release(&good_prefix);
425 return 0;
428 static int read_bisect_refs(void)
430 return for_each_ref_in("refs/bisect/", register_ref, NULL);
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 static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
437 static void read_bisect_paths(struct argv_array *array)
439 struct strbuf str = STRBUF_INIT;
440 const char *filename = git_path_bisect_names();
441 FILE *fp = fopen(filename, "r");
443 if (!fp)
444 die_errno(_("Could not open file '%s'"), filename);
446 while (strbuf_getline_lf(&str, fp) != EOF) {
447 strbuf_trim(&str);
448 if (sq_dequote_to_argv_array(str.buf, array))
449 die(_("Badly quoted content in file '%s': %s"),
450 filename, str.buf);
453 strbuf_release(&str);
454 fclose(fp);
457 static char *join_sha1_array_hex(struct oid_array *array, char delim)
459 struct strbuf joined_hexs = STRBUF_INIT;
460 int i;
462 for (i = 0; i < array->nr; i++) {
463 strbuf_addstr(&joined_hexs, oid_to_hex(array->oid + i));
464 if (i + 1 < array->nr)
465 strbuf_addch(&joined_hexs, delim);
468 return strbuf_detach(&joined_hexs, NULL);
472 * In this function, passing a not NULL skipped_first is very special.
473 * It means that we want to know if the first commit in the list is
474 * skipped because we will want to test a commit away from it if it is
475 * indeed skipped.
476 * So if the first commit is skipped, we cannot take the shortcut to
477 * just "return list" when we find the first non skipped commit, we
478 * have to return a fully filtered list.
480 * We use (*skipped_first == -1) to mean "it has been found that the
481 * first commit is not skipped". In this case *skipped_first is set back
482 * to 0 just before the function returns.
484 struct commit_list *filter_skipped(struct commit_list *list,
485 struct commit_list **tried,
486 int show_all,
487 int *count,
488 int *skipped_first)
490 struct commit_list *filtered = NULL, **f = &filtered;
492 *tried = NULL;
494 if (skipped_first)
495 *skipped_first = 0;
496 if (count)
497 *count = 0;
499 if (!skipped_revs.nr)
500 return list;
502 while (list) {
503 struct commit_list *next = list->next;
504 list->next = NULL;
505 if (0 <= oid_array_lookup(&skipped_revs, &list->item->object.oid)) {
506 if (skipped_first && !*skipped_first)
507 *skipped_first = 1;
508 /* Move current to tried list */
509 *tried = list;
510 tried = &list->next;
511 } else {
512 if (!show_all) {
513 if (!skipped_first || !*skipped_first)
514 return list;
515 } else if (skipped_first && !*skipped_first) {
516 /* This means we know it's not skipped */
517 *skipped_first = -1;
519 /* Move current to filtered list */
520 *f = list;
521 f = &list->next;
522 if (count)
523 (*count)++;
525 list = next;
528 if (skipped_first && *skipped_first == -1)
529 *skipped_first = 0;
531 return filtered;
534 #define PRN_MODULO 32768
537 * This is a pseudo random number generator based on "man 3 rand".
538 * It is not used properly because the seed is the argument and it
539 * is increased by one between each call, but that should not matter
540 * for this application.
542 static unsigned get_prn(unsigned count) {
543 count = count * 1103515245 + 12345;
544 return (count/65536) % PRN_MODULO;
548 * Custom integer square root from
549 * https://en.wikipedia.org/wiki/Integer_square_root
551 static int sqrti(int val)
553 float d, x = val;
555 if (val == 0)
556 return 0;
558 do {
559 float y = (x + (float)val / x) / 2;
560 d = (y > x) ? y - x : x - y;
561 x = y;
562 } while (d >= 0.5);
564 return (int)x;
567 static struct commit_list *skip_away(struct commit_list *list, int count)
569 struct commit_list *cur, *previous;
570 int prn, index, i;
572 prn = get_prn(count);
573 index = (count * prn / PRN_MODULO) * sqrti(prn) / sqrti(PRN_MODULO);
575 cur = list;
576 previous = NULL;
578 for (i = 0; cur; cur = cur->next, i++) {
579 if (i == index) {
580 if (oidcmp(&cur->item->object.oid, current_bad_oid))
581 return cur;
582 if (previous)
583 return previous;
584 return list;
586 previous = cur;
589 return list;
592 static struct commit_list *managed_skipped(struct commit_list *list,
593 struct commit_list **tried)
595 int count, skipped_first;
597 *tried = NULL;
599 if (!skipped_revs.nr)
600 return list;
602 list = filter_skipped(list, tried, 0, &count, &skipped_first);
604 if (!skipped_first)
605 return list;
607 return skip_away(list, count);
610 static void bisect_rev_setup(struct rev_info *revs, const char *prefix,
611 const char *bad_format, const char *good_format,
612 int read_paths)
614 struct argv_array rev_argv = ARGV_ARRAY_INIT;
615 int i;
617 init_revisions(revs, prefix);
618 revs->abbrev = 0;
619 revs->commit_format = CMIT_FMT_UNSPECIFIED;
621 /* rev_argv.argv[0] will be ignored by setup_revisions */
622 argv_array_push(&rev_argv, "bisect_rev_setup");
623 argv_array_pushf(&rev_argv, bad_format, oid_to_hex(current_bad_oid));
624 for (i = 0; i < good_revs.nr; i++)
625 argv_array_pushf(&rev_argv, good_format,
626 oid_to_hex(good_revs.oid + i));
627 argv_array_push(&rev_argv, "--");
628 if (read_paths)
629 read_bisect_paths(&rev_argv);
631 setup_revisions(rev_argv.argc, rev_argv.argv, revs, NULL);
632 /* XXX leak rev_argv, as "revs" may still be pointing to it */
635 static void bisect_common(struct rev_info *revs)
637 if (prepare_revision_walk(revs))
638 die("revision walk setup failed");
639 if (revs->tree_objects)
640 mark_edges_uninteresting(revs, NULL);
643 static void exit_if_skipped_commits(struct commit_list *tried,
644 const struct object_id *bad)
646 if (!tried)
647 return;
649 printf("There are only 'skip'ped commits left to test.\n"
650 "The first %s commit could be any of:\n", term_bad);
652 for ( ; tried; tried = tried->next)
653 printf("%s\n", oid_to_hex(&tried->item->object.oid));
655 if (bad)
656 printf("%s\n", oid_to_hex(bad));
657 printf(_("We cannot bisect more!\n"));
658 exit(2);
661 static int is_expected_rev(const struct object_id *oid)
663 const char *filename = git_path_bisect_expected_rev();
664 struct stat st;
665 struct strbuf str = STRBUF_INIT;
666 FILE *fp;
667 int res = 0;
669 if (stat(filename, &st) || !S_ISREG(st.st_mode))
670 return 0;
672 fp = fopen(filename, "r");
673 if (!fp)
674 return 0;
676 if (strbuf_getline_lf(&str, fp) != EOF)
677 res = !strcmp(str.buf, oid_to_hex(oid));
679 strbuf_release(&str);
680 fclose(fp);
682 return res;
685 static int bisect_checkout(const unsigned char *bisect_rev, int no_checkout)
687 char bisect_rev_hex[GIT_MAX_HEXSZ + 1];
689 memcpy(bisect_rev_hex, sha1_to_hex(bisect_rev), GIT_SHA1_HEXSZ + 1);
690 update_ref(NULL, "BISECT_EXPECTED_REV", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
692 argv_checkout[2] = bisect_rev_hex;
693 if (no_checkout) {
694 update_ref(NULL, "BISECT_HEAD", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
695 } else {
696 int res;
697 res = run_command_v_opt(argv_checkout, RUN_GIT_CMD);
698 if (res)
699 exit(res);
702 argv_show_branch[1] = bisect_rev_hex;
703 return run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
706 static struct commit *get_commit_reference(const struct object_id *oid)
708 struct commit *r = lookup_commit_reference(oid);
709 if (!r)
710 die(_("Not a valid commit name %s"), oid_to_hex(oid));
711 return r;
714 static struct commit **get_bad_and_good_commits(int *rev_nr)
716 struct commit **rev;
717 int i, n = 0;
719 ALLOC_ARRAY(rev, 1 + good_revs.nr);
720 rev[n++] = get_commit_reference(current_bad_oid);
721 for (i = 0; i < good_revs.nr; i++)
722 rev[n++] = get_commit_reference(good_revs.oid + i);
723 *rev_nr = n;
725 return rev;
728 static void handle_bad_merge_base(void)
730 if (is_expected_rev(current_bad_oid)) {
731 char *bad_hex = oid_to_hex(current_bad_oid);
732 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
733 if (!strcmp(term_bad, "bad") && !strcmp(term_good, "good")) {
734 fprintf(stderr, _("The merge base %s is bad.\n"
735 "This means the bug has been fixed "
736 "between %s and [%s].\n"),
737 bad_hex, bad_hex, good_hex);
738 } else if (!strcmp(term_bad, "new") && !strcmp(term_good, "old")) {
739 fprintf(stderr, _("The merge base %s is new.\n"
740 "The property has changed "
741 "between %s and [%s].\n"),
742 bad_hex, bad_hex, good_hex);
743 } else {
744 fprintf(stderr, _("The merge base %s is %s.\n"
745 "This means the first '%s' commit is "
746 "between %s and [%s].\n"),
747 bad_hex, term_bad, term_good, bad_hex, good_hex);
749 exit(3);
752 fprintf(stderr, _("Some %s revs are not ancestors of the %s rev.\n"
753 "git bisect cannot work properly in this case.\n"
754 "Maybe you mistook %s and %s revs?\n"),
755 term_good, term_bad, term_good, term_bad);
756 exit(1);
759 static void handle_skipped_merge_base(const struct object_id *mb)
761 char *mb_hex = oid_to_hex(mb);
762 char *bad_hex = oid_to_hex(current_bad_oid);
763 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
765 warning(_("the merge base between %s and [%s] "
766 "must be skipped.\n"
767 "So we cannot be sure the first %s commit is "
768 "between %s and %s.\n"
769 "We continue anyway."),
770 bad_hex, good_hex, term_bad, mb_hex, bad_hex);
771 free(good_hex);
775 * "check_merge_bases" checks that merge bases are not "bad" (or "new").
777 * - If one is "bad" (or "new"), it means the user assumed something wrong
778 * and we must exit with a non 0 error code.
779 * - If one is "good" (or "old"), that's good, we have nothing to do.
780 * - If one is "skipped", we can't know but we should warn.
781 * - If we don't know, we should check it out and ask the user to test.
783 static void check_merge_bases(int no_checkout)
785 struct commit_list *result;
786 int rev_nr;
787 struct commit **rev = get_bad_and_good_commits(&rev_nr);
789 result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1);
791 for (; result; result = result->next) {
792 const struct object_id *mb = &result->item->object.oid;
793 if (!oidcmp(mb, current_bad_oid)) {
794 handle_bad_merge_base();
795 } else if (0 <= oid_array_lookup(&good_revs, mb)) {
796 continue;
797 } else if (0 <= oid_array_lookup(&skipped_revs, mb)) {
798 handle_skipped_merge_base(mb);
799 } else {
800 printf(_("Bisecting: a merge base must be tested\n"));
801 exit(bisect_checkout(mb->hash, no_checkout));
805 free(rev);
806 free_commit_list(result);
809 static int check_ancestors(const char *prefix)
811 struct rev_info revs;
812 struct object_array pending_copy;
813 int res;
815 bisect_rev_setup(&revs, prefix, "^%s", "%s", 0);
817 /* Save pending objects, so they can be cleaned up later. */
818 pending_copy = revs.pending;
819 revs.leak_pending = 1;
822 * bisect_common calls prepare_revision_walk right away, which
823 * (together with .leak_pending = 1) makes us the sole owner of
824 * the list of pending objects.
826 bisect_common(&revs);
827 res = (revs.commits != NULL);
829 /* Clean up objects used, as they will be reused. */
830 clear_commit_marks_for_object_array(&pending_copy, ALL_REV_FLAGS);
831 free(pending_copy.objects);
833 return res;
837 * "check_good_are_ancestors_of_bad" checks that all "good" revs are
838 * ancestor of the "bad" rev.
840 * If that's not the case, we need to check the merge bases.
841 * If a merge base must be tested by the user, its source code will be
842 * checked out to be tested by the user and we will exit.
844 static void check_good_are_ancestors_of_bad(const char *prefix, int no_checkout)
846 char *filename = git_pathdup("BISECT_ANCESTORS_OK");
847 struct stat st;
848 int fd;
850 if (!current_bad_oid)
851 die(_("a %s revision is needed"), term_bad);
853 /* Check if file BISECT_ANCESTORS_OK exists. */
854 if (!stat(filename, &st) && S_ISREG(st.st_mode))
855 goto done;
857 /* Bisecting with no good rev is ok. */
858 if (good_revs.nr == 0)
859 goto done;
861 /* Check if all good revs are ancestor of the bad rev. */
862 if (check_ancestors(prefix))
863 check_merge_bases(no_checkout);
865 /* Create file BISECT_ANCESTORS_OK. */
866 fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
867 if (fd < 0)
868 warning_errno(_("could not create file '%s'"),
869 filename);
870 else
871 close(fd);
872 done:
873 free(filename);
877 * This does "git diff-tree --pretty COMMIT" without one fork+exec.
879 static void show_diff_tree(const char *prefix, struct commit *commit)
881 struct rev_info opt;
883 /* diff-tree init */
884 init_revisions(&opt, prefix);
885 git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
886 opt.abbrev = 0;
887 opt.diff = 1;
889 /* This is what "--pretty" does */
890 opt.verbose_header = 1;
891 opt.use_terminator = 0;
892 opt.commit_format = CMIT_FMT_DEFAULT;
894 /* diff-tree init */
895 if (!opt.diffopt.output_format)
896 opt.diffopt.output_format = DIFF_FORMAT_RAW;
898 setup_revisions(0, NULL, &opt, NULL);
899 log_tree_commit(&opt, commit);
903 * The terms used for this bisect session are stored in BISECT_TERMS.
904 * We read them and store them to adapt the messages accordingly.
905 * Default is bad/good.
907 void read_bisect_terms(const char **read_bad, const char **read_good)
909 struct strbuf str = STRBUF_INIT;
910 const char *filename = git_path_bisect_terms();
911 FILE *fp = fopen(filename, "r");
913 if (!fp) {
914 if (errno == ENOENT) {
915 *read_bad = "bad";
916 *read_good = "good";
917 return;
918 } else {
919 die_errno(_("could not read file '%s'"), filename);
921 } else {
922 strbuf_getline_lf(&str, fp);
923 *read_bad = strbuf_detach(&str, NULL);
924 strbuf_getline_lf(&str, fp);
925 *read_good = strbuf_detach(&str, NULL);
927 strbuf_release(&str);
928 fclose(fp);
932 * We use the convention that exiting with an exit code 10 means that
933 * the bisection process finished successfully.
934 * In this case the calling shell script should exit 0.
936 * If no_checkout is non-zero, the bisection process does not
937 * checkout the trial commit but instead simply updates BISECT_HEAD.
939 int bisect_next_all(const char *prefix, int no_checkout)
941 struct rev_info revs;
942 struct commit_list *tried;
943 int reaches = 0, all = 0, nr, steps;
944 const unsigned char *bisect_rev;
945 char *steps_msg;
947 read_bisect_terms(&term_bad, &term_good);
948 if (read_bisect_refs())
949 die(_("reading bisect refs failed"));
951 check_good_are_ancestors_of_bad(prefix, no_checkout);
953 bisect_rev_setup(&revs, prefix, "%s", "^%s", 1);
954 revs.limited = 1;
956 bisect_common(&revs);
958 revs.commits = find_bisection(revs.commits, &reaches, &all,
959 !!skipped_revs.nr);
960 revs.commits = managed_skipped(revs.commits, &tried);
962 if (!revs.commits) {
964 * We should exit here only if the "bad"
965 * commit is also a "skip" commit.
967 exit_if_skipped_commits(tried, NULL);
969 printf(_("%s was both %s and %s\n"),
970 oid_to_hex(current_bad_oid),
971 term_good,
972 term_bad);
973 exit(1);
976 if (!all) {
977 fprintf(stderr, _("No testable commit found.\n"
978 "Maybe you started with bad path parameters?\n"));
979 exit(4);
982 bisect_rev = revs.commits->item->object.oid.hash;
984 if (!hashcmp(bisect_rev, current_bad_oid->hash)) {
985 exit_if_skipped_commits(tried, current_bad_oid);
986 printf("%s is the first %s commit\n", sha1_to_hex(bisect_rev),
987 term_bad);
988 show_diff_tree(prefix, revs.commits->item);
989 /* This means the bisection process succeeded. */
990 exit(10);
993 nr = all - reaches - 1;
994 steps = estimate_bisect_steps(all);
996 steps_msg = xstrfmt(Q_("(roughly %d step)", "(roughly %d steps)",
997 steps), steps);
999 * TRANSLATORS: the last %s will be replaced with "(roughly %d
1000 * steps)" translation.
1002 printf(Q_("Bisecting: %d revision left to test after this %s\n",
1003 "Bisecting: %d revisions left to test after this %s\n",
1004 nr), nr, steps_msg);
1005 free(steps_msg);
1007 return bisect_checkout(bisect_rev, no_checkout);
1010 static inline int log2i(int n)
1012 int log2 = 0;
1014 for (; n > 1; n >>= 1)
1015 log2++;
1017 return log2;
1020 static inline int exp2i(int n)
1022 return 1 << n;
1026 * Estimate the number of bisect steps left (after the current step)
1028 * For any x between 0 included and 2^n excluded, the probability for
1029 * n - 1 steps left looks like:
1031 * P(2^n + x) == (2^n - x) / (2^n + x)
1033 * and P(2^n + x) < 0.5 means 2^n < 3x
1035 int estimate_bisect_steps(int all)
1037 int n, x, e;
1039 if (all < 3)
1040 return 0;
1042 n = log2i(all);
1043 e = exp2i(n);
1044 x = all - e;
1046 return (e < 3 * x) ? n : n - 1;