object.h: centralize object flag allocation
[git/git.git] / bisect.c
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1#include "cache.h"
2#include "commit.h"
3#include "diff.h"
4#include "revision.h"
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5#include "refs.h"
6#include "list-objects.h"
3b437b0d 7#include "quote.h"
4eb5b646 8#include "sha1-lookup.h"
ef24c7ca 9#include "run-command.h"
e22278c0 10#include "log-tree.h"
a2ad79ce 11#include "bisect.h"
902bb364 12#include "sha1-array.h"
8a534b61 13#include "argv-array.h"
6212b1aa 14
fad2d31d 15static struct sha1_array good_revs;
6212b1aa 16static struct sha1_array skipped_revs;
1bf072e3 17
bf42772e 18static unsigned char *current_bad_sha1;
ef24c7ca 19
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20static const char *argv_checkout[] = {"checkout", "-q", NULL, "--", NULL};
21static const char *argv_show_branch[] = {"show-branch", NULL, NULL};
fee92fc1 22static const char *argv_update_ref[] = {"update-ref", "--no-deref", "BISECT_HEAD", NULL, NULL};
ef24c7ca 23
208acbfb 24/* Remember to update object flag allocation in object.h */
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25#define COUNTED (1u<<16)
26
27/*
28 * This is a truly stupid algorithm, but it's only
29 * used for bisection, and we just don't care enough.
30 *
31 * We care just barely enough to avoid recursing for
32 * non-merge entries.
33 */
34static int count_distance(struct commit_list *entry)
35{
36 int nr = 0;
37
38 while (entry) {
39 struct commit *commit = entry->item;
40 struct commit_list *p;
41
42 if (commit->object.flags & (UNINTERESTING | COUNTED))
43 break;
44 if (!(commit->object.flags & TREESAME))
45 nr++;
46 commit->object.flags |= COUNTED;
47 p = commit->parents;
48 entry = p;
49 if (p) {
50 p = p->next;
51 while (p) {
52 nr += count_distance(p);
53 p = p->next;
54 }
55 }
56 }
57
58 return nr;
59}
60
61static void clear_distance(struct commit_list *list)
62{
63 while (list) {
64 struct commit *commit = list->item;
65 commit->object.flags &= ~COUNTED;
66 list = list->next;
67 }
68}
69
70#define DEBUG_BISECT 0
71
72static inline int weight(struct commit_list *elem)
73{
74 return *((int*)(elem->item->util));
75}
76
77static inline void weight_set(struct commit_list *elem, int weight)
78{
79 *((int*)(elem->item->util)) = weight;
80}
81
82static int count_interesting_parents(struct commit *commit)
83{
84 struct commit_list *p;
85 int count;
86
87 for (count = 0, p = commit->parents; p; p = p->next) {
88 if (p->item->object.flags & UNINTERESTING)
89 continue;
90 count++;
91 }
92 return count;
93}
94
95static inline int halfway(struct commit_list *p, int nr)
96{
97 /*
98 * Don't short-cut something we are not going to return!
99 */
100 if (p->item->object.flags & TREESAME)
101 return 0;
102 if (DEBUG_BISECT)
103 return 0;
104 /*
105 * 2 and 3 are halfway of 5.
106 * 3 is halfway of 6 but 2 and 4 are not.
107 */
108 switch (2 * weight(p) - nr) {
109 case -1: case 0: case 1:
110 return 1;
111 default:
112 return 0;
113 }
114}
115
116#if !DEBUG_BISECT
117#define show_list(a,b,c,d) do { ; } while (0)
118#else
119static void show_list(const char *debug, int counted, int nr,
120 struct commit_list *list)
121{
122 struct commit_list *p;
123
124 fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr);
125
126 for (p = list; p; p = p->next) {
127 struct commit_list *pp;
128 struct commit *commit = p->item;
129 unsigned flags = commit->object.flags;
130 enum object_type type;
131 unsigned long size;
132 char *buf = read_sha1_file(commit->object.sha1, &type, &size);
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133 const char *subject_start;
134 int subject_len;
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135
136 fprintf(stderr, "%c%c%c ",
137 (flags & TREESAME) ? ' ' : 'T',
138 (flags & UNINTERESTING) ? 'U' : ' ',
139 (flags & COUNTED) ? 'C' : ' ');
140 if (commit->util)
141 fprintf(stderr, "%3d", weight(p));
142 else
143 fprintf(stderr, "---");
144 fprintf(stderr, " %.*s", 8, sha1_to_hex(commit->object.sha1));
145 for (pp = commit->parents; pp; pp = pp->next)
146 fprintf(stderr, " %.*s", 8,
147 sha1_to_hex(pp->item->object.sha1));
148
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149 subject_len = find_commit_subject(buf, &subject_start);
150 if (subject_len)
151 fprintf(stderr, " %.*s", subject_len, subject_start);
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152 fprintf(stderr, "\n");
153 }
154}
155#endif /* DEBUG_BISECT */
156
157static struct commit_list *best_bisection(struct commit_list *list, int nr)
158{
159 struct commit_list *p, *best;
160 int best_distance = -1;
161
162 best = list;
163 for (p = list; p; p = p->next) {
164 int distance;
165 unsigned flags = p->item->object.flags;
166
167 if (flags & TREESAME)
168 continue;
169 distance = weight(p);
170 if (nr - distance < distance)
171 distance = nr - distance;
172 if (distance > best_distance) {
173 best = p;
174 best_distance = distance;
175 }
176 }
177
178 return best;
179}
180
181struct commit_dist {
182 struct commit *commit;
183 int distance;
184};
185
186static int compare_commit_dist(const void *a_, const void *b_)
187{
188 struct commit_dist *a, *b;
189
190 a = (struct commit_dist *)a_;
191 b = (struct commit_dist *)b_;
192 if (a->distance != b->distance)
193 return b->distance - a->distance; /* desc sort */
194 return hashcmp(a->commit->object.sha1, b->commit->object.sha1);
195}
196
197static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
198{
199 struct commit_list *p;
200 struct commit_dist *array = xcalloc(nr, sizeof(*array));
201 int cnt, i;
202
203 for (p = list, cnt = 0; p; p = p->next) {
204 int distance;
205 unsigned flags = p->item->object.flags;
206
207 if (flags & TREESAME)
208 continue;
209 distance = weight(p);
210 if (nr - distance < distance)
211 distance = nr - distance;
212 array[cnt].commit = p->item;
213 array[cnt].distance = distance;
214 cnt++;
215 }
216 qsort(array, cnt, sizeof(*array), compare_commit_dist);
217 for (p = list, i = 0; i < cnt; i++) {
218 struct name_decoration *r = xmalloc(sizeof(*r) + 100);
219 struct object *obj = &(array[i].commit->object);
220
221 sprintf(r->name, "dist=%d", array[i].distance);
222 r->next = add_decoration(&name_decoration, obj, r);
223 p->item = array[i].commit;
224 p = p->next;
225 }
226 if (p)
227 p->next = NULL;
228 free(array);
229 return list;
230}
231
232/*
233 * zero or positive weight is the number of interesting commits it can
234 * reach, including itself. Especially, weight = 0 means it does not
235 * reach any tree-changing commits (e.g. just above uninteresting one
236 * but traversal is with pathspec).
237 *
238 * weight = -1 means it has one parent and its distance is yet to
239 * be computed.
240 *
241 * weight = -2 means it has more than one parent and its distance is
242 * unknown. After running count_distance() first, they will get zero
243 * or positive distance.
244 */
245static struct commit_list *do_find_bisection(struct commit_list *list,
246 int nr, int *weights,
247 int find_all)
248{
249 int n, counted;
250 struct commit_list *p;
251
252 counted = 0;
253
254 for (n = 0, p = list; p; p = p->next) {
255 struct commit *commit = p->item;
256 unsigned flags = commit->object.flags;
257
258 p->item->util = &weights[n++];
259 switch (count_interesting_parents(commit)) {
260 case 0:
261 if (!(flags & TREESAME)) {
262 weight_set(p, 1);
263 counted++;
264 show_list("bisection 2 count one",
265 counted, nr, list);
266 }
267 /*
268 * otherwise, it is known not to reach any
269 * tree-changing commit and gets weight 0.
270 */
271 break;
272 case 1:
273 weight_set(p, -1);
274 break;
275 default:
276 weight_set(p, -2);
277 break;
278 }
279 }
280
281 show_list("bisection 2 initialize", counted, nr, list);
282
283 /*
284 * If you have only one parent in the resulting set
285 * then you can reach one commit more than that parent
286 * can reach. So we do not have to run the expensive
287 * count_distance() for single strand of pearls.
288 *
289 * However, if you have more than one parents, you cannot
290 * just add their distance and one for yourself, since
291 * they usually reach the same ancestor and you would
292 * end up counting them twice that way.
293 *
294 * So we will first count distance of merges the usual
295 * way, and then fill the blanks using cheaper algorithm.
296 */
297 for (p = list; p; p = p->next) {
298 if (p->item->object.flags & UNINTERESTING)
299 continue;
300 if (weight(p) != -2)
301 continue;
302 weight_set(p, count_distance(p));
303 clear_distance(list);
304
305 /* Does it happen to be at exactly half-way? */
306 if (!find_all && halfway(p, nr))
307 return p;
308 counted++;
309 }
310
311 show_list("bisection 2 count_distance", counted, nr, list);
312
313 while (counted < nr) {
314 for (p = list; p; p = p->next) {
315 struct commit_list *q;
316 unsigned flags = p->item->object.flags;
317
318 if (0 <= weight(p))
319 continue;
320 for (q = p->item->parents; q; q = q->next) {
321 if (q->item->object.flags & UNINTERESTING)
322 continue;
323 if (0 <= weight(q))
324 break;
325 }
326 if (!q)
327 continue;
328
329 /*
330 * weight for p is unknown but q is known.
331 * add one for p itself if p is to be counted,
332 * otherwise inherit it from q directly.
333 */
334 if (!(flags & TREESAME)) {
335 weight_set(p, weight(q)+1);
336 counted++;
337 show_list("bisection 2 count one",
338 counted, nr, list);
339 }
340 else
341 weight_set(p, weight(q));
342
343 /* Does it happen to be at exactly half-way? */
344 if (!find_all && halfway(p, nr))
345 return p;
346 }
347 }
348
349 show_list("bisection 2 counted all", counted, nr, list);
350
351 if (!find_all)
352 return best_bisection(list, nr);
353 else
354 return best_bisection_sorted(list, nr);
355}
356
357struct commit_list *find_bisection(struct commit_list *list,
358 int *reaches, int *all,
359 int find_all)
360{
361 int nr, on_list;
362 struct commit_list *p, *best, *next, *last;
363 int *weights;
364
365 show_list("bisection 2 entry", 0, 0, list);
366
367 /*
368 * Count the number of total and tree-changing items on the
369 * list, while reversing the list.
370 */
371 for (nr = on_list = 0, last = NULL, p = list;
372 p;
373 p = next) {
374 unsigned flags = p->item->object.flags;
375
376 next = p->next;
377 if (flags & UNINTERESTING)
378 continue;
379 p->next = last;
380 last = p;
381 if (!(flags & TREESAME))
382 nr++;
383 on_list++;
384 }
385 list = last;
386 show_list("bisection 2 sorted", 0, nr, list);
387
388 *all = nr;
389 weights = xcalloc(on_list, sizeof(*weights));
390
391 /* Do the real work of finding bisection commit. */
392 best = do_find_bisection(list, nr, weights, find_all);
393 if (best) {
394 if (!find_all)
395 best->next = NULL;
396 *reaches = weight(best);
397 }
398 free(weights);
399 return best;
400}
401
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402static int register_ref(const char *refname, const unsigned char *sha1,
403 int flags, void *cb_data)
404{
405 if (!strcmp(refname, "bad")) {
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406 current_bad_sha1 = xmalloc(20);
407 hashcpy(current_bad_sha1, sha1);
59556548 408 } else if (starts_with(refname, "good-")) {
902bb364 409 sha1_array_append(&good_revs, sha1);
59556548 410 } else if (starts_with(refname, "skip-")) {
902bb364 411 sha1_array_append(&skipped_revs, sha1);
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412 }
413
414 return 0;
415}
416
417static int read_bisect_refs(void)
418{
419 return for_each_ref_in("refs/bisect/", register_ref, NULL);
420}
421
2af202be 422static void read_bisect_paths(struct argv_array *array)
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423{
424 struct strbuf str = STRBUF_INIT;
425 const char *filename = git_path("BISECT_NAMES");
426 FILE *fp = fopen(filename, "r");
427
428 if (!fp)
d824cbba 429 die_errno("Could not open file '%s'", filename);
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430
431 while (strbuf_getline(&str, fp, '\n') != EOF) {
3b437b0d 432 strbuf_trim(&str);
8a534b61 433 if (sq_dequote_to_argv_array(str.buf, array))
3b437b0d 434 die("Badly quoted content in file '%s': %s",
8a534b61 435 filename, str.buf);
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436 }
437
438 strbuf_release(&str);
439 fclose(fp);
440}
441
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442static char *join_sha1_array_hex(struct sha1_array *array, char delim)
443{
444 struct strbuf joined_hexs = STRBUF_INIT;
445 int i;
446
902bb364 447 for (i = 0; i < array->nr; i++) {
c0537662 448 strbuf_addstr(&joined_hexs, sha1_to_hex(array->sha1[i]));
902bb364 449 if (i + 1 < array->nr)
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450 strbuf_addch(&joined_hexs, delim);
451 }
452
453 return strbuf_detach(&joined_hexs, NULL);
454}
455
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456/*
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.
464 *
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.
468 */
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469struct commit_list *filter_skipped(struct commit_list *list,
470 struct commit_list **tried,
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471 int show_all,
472 int *count,
473 int *skipped_first)
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474{
475 struct commit_list *filtered = NULL, **f = &filtered;
476
477 *tried = NULL;
478
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479 if (skipped_first)
480 *skipped_first = 0;
481 if (count)
482 *count = 0;
483
902bb364 484 if (!skipped_revs.nr)
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485 return list;
486
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487 while (list) {
488 struct commit_list *next = list->next;
489 list->next = NULL;
902bb364 490 if (0 <= sha1_array_lookup(&skipped_revs,
aaaff9e2 491 list->item->object.sha1)) {
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492 if (skipped_first && !*skipped_first)
493 *skipped_first = 1;
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494 /* Move current to tried list */
495 *tried = list;
496 tried = &list->next;
497 } else {
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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;
504 }
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505 /* Move current to filtered list */
506 *f = list;
507 f = &list->next;
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508 if (count)
509 (*count)++;
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510 }
511 list = next;
512 }
513
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514 if (skipped_first && *skipped_first == -1)
515 *skipped_first = 0;
516
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517 return filtered;
518}
1bf072e3 519
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520#define PRN_MODULO 32768
521
522/*
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.
527 */
7b96d888 528static unsigned get_prn(unsigned count) {
ebc9529f 529 count = count * 1103515245 + 12345;
7b96d888 530 return (count/65536) % PRN_MODULO;
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531}
532
533/*
534 * Custom integer square root from
535 * http://en.wikipedia.org/wiki/Integer_square_root
536 */
537static int sqrti(int val)
538{
539 float d, x = val;
540
541 if (val == 0)
542 return 0;
543
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);
549
550 return (int)x;
551}
552
553static struct commit_list *skip_away(struct commit_list *list, int count)
62d0b0da 554{
62d0b0da 555 struct commit_list *cur, *previous;
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556 int prn, index, i;
557
558 prn = get_prn(count);
559 index = (count * prn / PRN_MODULO) * sqrti(prn) / sqrti(PRN_MODULO);
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560
561 cur = list;
562 previous = NULL;
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563
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;
571 }
572 previous = cur;
573 }
574
575 return list;
576}
577
578static struct commit_list *managed_skipped(struct commit_list *list,
579 struct commit_list **tried)
580{
581 int count, skipped_first;
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582
583 *tried = NULL;
584
902bb364 585 if (!skipped_revs.nr)
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586 return list;
587
588 list = filter_skipped(list, tried, 0, &count, &skipped_first);
589
590 if (!skipped_first)
591 return list;
592
ebc9529f 593 return skip_away(list, count);
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594}
595
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596static void bisect_rev_setup(struct rev_info *revs, const char *prefix,
597 const char *bad_format, const char *good_format,
598 int read_paths)
1bf072e3 599{
8a534b61 600 struct argv_array rev_argv = ARGV_ARRAY_INIT;
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601 int i;
602
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603 init_revisions(revs, prefix);
604 revs->abbrev = 0;
605 revs->commit_format = CMIT_FMT_UNSPECIFIED;
1bf072e3 606
1c953a1f 607 /* rev_argv.argv[0] will be ignored by setup_revisions */
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608 argv_array_push(&rev_argv, "bisect_rev_setup");
609 argv_array_pushf(&rev_argv, bad_format, sha1_to_hex(current_bad_sha1));
902bb364 610 for (i = 0; i < good_revs.nr; i++)
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611 argv_array_pushf(&rev_argv, good_format,
612 sha1_to_hex(good_revs.sha1[i]));
613 argv_array_push(&rev_argv, "--");
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614 if (read_paths)
615 read_bisect_paths(&rev_argv);
3b437b0d 616
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617 setup_revisions(rev_argv.argc, rev_argv.argv, revs, NULL);
618 /* XXX leak rev_argv, as "revs" may still be pointing to it */
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619}
620
a22347c6 621static void bisect_common(struct rev_info *revs)
2ace9727 622{
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623 if (prepare_revision_walk(revs))
624 die("revision walk setup failed");
625 if (revs->tree_objects)
e76a5fb4 626 mark_edges_uninteresting(revs, NULL);
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627}
628
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629static void exit_if_skipped_commits(struct commit_list *tried,
630 const unsigned char *bad)
631{
632 if (!tried)
633 return;
634
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);
642}
643
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644static int is_expected_rev(const unsigned char *sha1)
645{
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;
651
652 if (stat(filename, &st) || !S_ISREG(st.st_mode))
653 return 0;
654
655 fp = fopen(filename, "r");
656 if (!fp)
657 return 0;
658
659 if (strbuf_getline(&str, fp, '\n') != EOF)
660 res = !strcmp(str.buf, sha1_to_hex(sha1));
661
662 strbuf_release(&str);
663 fclose(fp);
664
665 return res;
666}
667
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668static void mark_expected_rev(char *bisect_rev_hex)
669{
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);
673
674 if (fd < 0)
d824cbba 675 die_errno("could not create file '%s'", filename);
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676
677 bisect_rev_hex[len] = '\n';
678 write_or_die(fd, bisect_rev_hex, len + 1);
679 bisect_rev_hex[len] = '\0';
680
681 if (close(fd) < 0)
682 die("closing file %s: %s", filename, strerror(errno));
683}
684
fee92fc1 685static int bisect_checkout(char *bisect_rev_hex, int no_checkout)
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686{
687 int res;
688
689 mark_expected_rev(bisect_rev_hex);
690
691 argv_checkout[2] = bisect_rev_hex;
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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);
701 }
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702
703 argv_show_branch[1] = bisect_rev_hex;
704 return run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
705}
706
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707static struct commit *get_commit_reference(const unsigned char *sha1)
708{
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;
713}
714
715static struct commit **get_bad_and_good_commits(int *rev_nr)
716{
902bb364 717 int len = 1 + good_revs.nr;
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718 struct commit **rev = xmalloc(len * sizeof(*rev));
719 int i, n = 0;
720
721 rev[n++] = get_commit_reference(current_bad_sha1);
902bb364 722 for (i = 0; i < good_revs.nr; i++)
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CC
723 rev[n++] = get_commit_reference(good_revs.sha1[i]);
724 *rev_nr = n;
725
726 return rev;
727}
728
729static void handle_bad_merge_base(void)
730{
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, ' ');
734
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);
739
740 exit(3);
741 }
742
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);
747}
748
2af202be 749static void handle_skipped_merge_base(const unsigned char *mb)
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CC
750{
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, ' ');
754
bd757c18 755 warning("the merge base between %s and [%s] "
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CC
756 "must be skipped.\n"
757 "So we cannot be sure the first bad commit is "
758 "between %s and %s.\n"
bd757c18 759 "We continue anyway.",
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760 bad_hex, good_hex, mb_hex, bad_hex);
761 free(good_hex);
762}
763
764/*
765 * "check_merge_bases" checks that merge bases are not "bad".
766 *
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.
772 */
fee92fc1 773static void check_merge_bases(int no_checkout)
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CC
774{
775 struct commit_list *result;
776 int rev_nr;
777 struct commit **rev = get_bad_and_good_commits(&rev_nr);
778
779 result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1, 0);
780
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();
902bb364 785 } else if (0 <= sha1_array_lookup(&good_revs, mb)) {
c0537662 786 continue;
902bb364 787 } else if (0 <= sha1_array_lookup(&skipped_revs, mb)) {
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788 handle_skipped_merge_base(mb);
789 } else {
790 printf("Bisecting: a merge base must be tested\n");
fee92fc1 791 exit(bisect_checkout(sha1_to_hex(mb), no_checkout));
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792 }
793 }
794
795 free(rev);
796 free_commit_list(result);
797}
798
2d938fc7 799static int check_ancestors(const char *prefix)
d937d4ac 800{
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CC
801 struct rev_info revs;
802 struct object_array pending_copy;
86a0a408 803 int res;
d937d4ac 804
2d938fc7 805 bisect_rev_setup(&revs, prefix, "^%s", "%s", 0);
d937d4ac 806
2d938fc7 807 /* Save pending objects, so they can be cleaned up later. */
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RS
808 pending_copy = revs.pending;
809 revs.leak_pending = 1;
2d938fc7 810
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811 /*
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.
815 */
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CC
816 bisect_common(&revs);
817 res = (revs.commits != NULL);
818
819 /* Clean up objects used, as they will be reused. */
86a0a408 820 clear_commit_marks_for_object_array(&pending_copy, ALL_REV_FLAGS);
353f5657 821 free(pending_copy.objects);
d937d4ac 822
2d938fc7 823 return res;
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CC
824}
825
826/*
827 * "check_good_are_ancestors_of_bad" checks that all "good" revs are
828 * ancestor of the "bad" rev.
829 *
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.
833 */
fee92fc1 834static void check_good_are_ancestors_of_bad(const char *prefix, int no_checkout)
d937d4ac 835{
d292bfaf 836 char *filename = git_pathdup("BISECT_ANCESTORS_OK");
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CC
837 struct stat st;
838 int fd;
839
840 if (!current_bad_sha1)
841 die("a bad revision is needed");
842
843 /* Check if file BISECT_ANCESTORS_OK exists. */
844 if (!stat(filename, &st) && S_ISREG(st.st_mode))
144e7090 845 goto done;
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CC
846
847 /* Bisecting with no good rev is ok. */
902bb364 848 if (good_revs.nr == 0)
144e7090 849 goto done;
d937d4ac 850
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CC
851 /* Check if all good revs are ancestor of the bad rev. */
852 if (check_ancestors(prefix))
fee92fc1 853 check_merge_bases(no_checkout);
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CC
854
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);
144e7090
MH
862 done:
863 free(filename);
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CC
864}
865
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CC
866/*
867 * This does "git diff-tree --pretty COMMIT" without one fork+exec.
868 */
869static void show_diff_tree(const char *prefix, struct commit *commit)
870{
871 struct rev_info opt;
872
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;
878
879 /* This is what "--pretty" does */
880 opt.verbose_header = 1;
881 opt.use_terminator = 0;
882 opt.commit_format = CMIT_FMT_DEFAULT;
883
884 /* diff-tree init */
885 if (!opt.diffopt.output_format)
886 opt.diffopt.output_format = DIFF_FORMAT_RAW;
887
888 log_tree_commit(&opt, commit);
889}
890
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CC
891/*
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.
fee92fc1
JS
895 *
896 * If no_checkout is non-zero, the bisection process does not
897 * checkout the trial commit but instead simply updates BISECT_HEAD.
ef24c7ca 898 */
fee92fc1 899int bisect_next_all(const char *prefix, int no_checkout)
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CC
900{
901 struct rev_info revs;
902 struct commit_list *tried;
6329bade 903 int reaches = 0, all = 0, nr, steps;
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CC
904 const unsigned char *bisect_rev;
905 char bisect_rev_hex[41];
906
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CC
907 if (read_bisect_refs())
908 die("reading bisect refs failed");
909
fee92fc1 910 check_good_are_ancestors_of_bad(prefix, no_checkout);
0871984d 911
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CC
912 bisect_rev_setup(&revs, prefix, "%s", "^%s", 1);
913 revs.limited = 1;
2b020695 914
a22347c6 915 bisect_common(&revs);
ef24c7ca 916
a22347c6 917 revs.commits = find_bisection(revs.commits, &reaches, &all,
902bb364 918 !!skipped_revs.nr);
62d0b0da 919 revs.commits = managed_skipped(revs.commits, &tried);
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CC
920
921 if (!revs.commits) {
922 /*
923 * We should exit here only if the "bad"
924 * commit is also a "skip" commit.
925 */
926 exit_if_skipped_commits(tried, NULL);
927
928 printf("%s was both good and bad\n",
929 sha1_to_hex(current_bad_sha1));
930 exit(1);
931 }
932
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CC
933 if (!all) {
934 fprintf(stderr, "No testable commit found.\n"
935 "Maybe you started with bad path parameters?\n");
936 exit(4);
937 }
938
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CC
939 bisect_rev = revs.commits->item->object.sha1;
940 memcpy(bisect_rev_hex, sha1_to_hex(bisect_rev), 41);
941
942 if (!hashcmp(bisect_rev, current_bad_sha1)) {
943 exit_if_skipped_commits(tried, current_bad_sha1);
21d0bc2f 944 printf("%s is the first bad commit\n", bisect_rev_hex);
e22278c0 945 show_diff_tree(prefix, revs.commits->item);
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CC
946 /* This means the bisection process succeeded. */
947 exit(10);
948 }
949
950 nr = all - reaches - 1;
6329bade
DR
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"));
ef24c7ca 955
fee92fc1 956 return bisect_checkout(bisect_rev_hex, no_checkout);
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CC
957}
958
c43cb386
NTND
959static inline int log2i(int n)
960{
961 int log2 = 0;
962
963 for (; n > 1; n >>= 1)
964 log2++;
965
966 return log2;
967}
968
969static inline int exp2i(int n)
970{
971 return 1 << n;
972}
973
974/*
975 * Estimate the number of bisect steps left (after the current step)
976 *
977 * For any x between 0 included and 2^n excluded, the probability for
978 * n - 1 steps left looks like:
979 *
980 * P(2^n + x) == (2^n - x) / (2^n + x)
981 *
982 * and P(2^n + x) < 0.5 means 2^n < 3x
983 */
984int estimate_bisect_steps(int all)
985{
986 int n, x, e;
987
988 if (all < 3)
989 return 0;
990
991 n = log2i(all);
992 e = exp2i(n);
993 x = all - e;
994
995 return (e < 3 * x) ? n : n - 1;
996}