bisect: replace hardcoded "bad|good" by variables
[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
3c5ff995 18static struct object_id *current_bad_oid;
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
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24static const char *term_bad;
25static const char *term_good;
26
208acbfb 27/* Remember to update object flag allocation in object.h */
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28#define COUNTED (1u<<16)
29
30/*
31 * This is a truly stupid algorithm, but it's only
32 * used for bisection, and we just don't care enough.
33 *
34 * We care just barely enough to avoid recursing for
35 * non-merge entries.
36 */
37static int count_distance(struct commit_list *entry)
38{
39 int nr = 0;
40
41 while (entry) {
42 struct commit *commit = entry->item;
43 struct commit_list *p;
44
45 if (commit->object.flags & (UNINTERESTING | COUNTED))
46 break;
47 if (!(commit->object.flags & TREESAME))
48 nr++;
49 commit->object.flags |= COUNTED;
50 p = commit->parents;
51 entry = p;
52 if (p) {
53 p = p->next;
54 while (p) {
55 nr += count_distance(p);
56 p = p->next;
57 }
58 }
59 }
60
61 return nr;
62}
63
64static void clear_distance(struct commit_list *list)
65{
66 while (list) {
67 struct commit *commit = list->item;
68 commit->object.flags &= ~COUNTED;
69 list = list->next;
70 }
71}
72
73#define DEBUG_BISECT 0
74
75static inline int weight(struct commit_list *elem)
76{
77 return *((int*)(elem->item->util));
78}
79
80static inline void weight_set(struct commit_list *elem, int weight)
81{
82 *((int*)(elem->item->util)) = weight;
83}
84
85static int count_interesting_parents(struct commit *commit)
86{
87 struct commit_list *p;
88 int count;
89
90 for (count = 0, p = commit->parents; p; p = p->next) {
91 if (p->item->object.flags & UNINTERESTING)
92 continue;
93 count++;
94 }
95 return count;
96}
97
98static inline int halfway(struct commit_list *p, int nr)
99{
100 /*
101 * Don't short-cut something we are not going to return!
102 */
103 if (p->item->object.flags & TREESAME)
104 return 0;
105 if (DEBUG_BISECT)
106 return 0;
107 /*
108 * 2 and 3 are halfway of 5.
109 * 3 is halfway of 6 but 2 and 4 are not.
110 */
111 switch (2 * weight(p) - nr) {
112 case -1: case 0: case 1:
113 return 1;
114 default:
115 return 0;
116 }
117}
118
119#if !DEBUG_BISECT
120#define show_list(a,b,c,d) do { ; } while (0)
121#else
122static void show_list(const char *debug, int counted, int nr,
123 struct commit_list *list)
124{
125 struct commit_list *p;
126
127 fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr);
128
129 for (p = list; p; p = p->next) {
130 struct commit_list *pp;
131 struct commit *commit = p->item;
132 unsigned flags = commit->object.flags;
133 enum object_type type;
134 unsigned long size;
135 char *buf = read_sha1_file(commit->object.sha1, &type, &size);
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136 const char *subject_start;
137 int subject_len;
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138
139 fprintf(stderr, "%c%c%c ",
140 (flags & TREESAME) ? ' ' : 'T',
141 (flags & UNINTERESTING) ? 'U' : ' ',
142 (flags & COUNTED) ? 'C' : ' ');
143 if (commit->util)
144 fprintf(stderr, "%3d", weight(p));
145 else
146 fprintf(stderr, "---");
147 fprintf(stderr, " %.*s", 8, sha1_to_hex(commit->object.sha1));
148 for (pp = commit->parents; pp; pp = pp->next)
149 fprintf(stderr, " %.*s", 8,
150 sha1_to_hex(pp->item->object.sha1));
151
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152 subject_len = find_commit_subject(buf, &subject_start);
153 if (subject_len)
154 fprintf(stderr, " %.*s", subject_len, subject_start);
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155 fprintf(stderr, "\n");
156 }
157}
158#endif /* DEBUG_BISECT */
159
160static struct commit_list *best_bisection(struct commit_list *list, int nr)
161{
162 struct commit_list *p, *best;
163 int best_distance = -1;
164
165 best = list;
166 for (p = list; p; p = p->next) {
167 int distance;
168 unsigned flags = p->item->object.flags;
169
170 if (flags & TREESAME)
171 continue;
172 distance = weight(p);
173 if (nr - distance < distance)
174 distance = nr - distance;
175 if (distance > best_distance) {
176 best = p;
177 best_distance = distance;
178 }
179 }
180
181 return best;
182}
183
184struct commit_dist {
185 struct commit *commit;
186 int distance;
187};
188
189static int compare_commit_dist(const void *a_, const void *b_)
190{
191 struct commit_dist *a, *b;
192
193 a = (struct commit_dist *)a_;
194 b = (struct commit_dist *)b_;
195 if (a->distance != b->distance)
196 return b->distance - a->distance; /* desc sort */
197 return hashcmp(a->commit->object.sha1, b->commit->object.sha1);
198}
199
200static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
201{
202 struct commit_list *p;
203 struct commit_dist *array = xcalloc(nr, sizeof(*array));
204 int cnt, i;
205
206 for (p = list, cnt = 0; p; p = p->next) {
207 int distance;
208 unsigned flags = p->item->object.flags;
209
210 if (flags & TREESAME)
211 continue;
212 distance = weight(p);
213 if (nr - distance < distance)
214 distance = nr - distance;
215 array[cnt].commit = p->item;
216 array[cnt].distance = distance;
217 cnt++;
218 }
219 qsort(array, cnt, sizeof(*array), compare_commit_dist);
220 for (p = list, i = 0; i < cnt; i++) {
662174d2 221 char buf[100]; /* enough for dist=%d */
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222 struct object *obj = &(array[i].commit->object);
223
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224 snprintf(buf, sizeof(buf), "dist=%d", array[i].distance);
225 add_name_decoration(DECORATION_NONE, buf, obj);
226
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227 p->item = array[i].commit;
228 p = p->next;
229 }
230 if (p)
231 p->next = NULL;
232 free(array);
233 return list;
234}
235
236/*
237 * zero or positive weight is the number of interesting commits it can
238 * reach, including itself. Especially, weight = 0 means it does not
239 * reach any tree-changing commits (e.g. just above uninteresting one
240 * but traversal is with pathspec).
241 *
242 * weight = -1 means it has one parent and its distance is yet to
243 * be computed.
244 *
245 * weight = -2 means it has more than one parent and its distance is
246 * unknown. After running count_distance() first, they will get zero
247 * or positive distance.
248 */
249static struct commit_list *do_find_bisection(struct commit_list *list,
250 int nr, int *weights,
251 int find_all)
252{
253 int n, counted;
254 struct commit_list *p;
255
256 counted = 0;
257
258 for (n = 0, p = list; p; p = p->next) {
259 struct commit *commit = p->item;
260 unsigned flags = commit->object.flags;
261
262 p->item->util = &weights[n++];
263 switch (count_interesting_parents(commit)) {
264 case 0:
265 if (!(flags & TREESAME)) {
266 weight_set(p, 1);
267 counted++;
268 show_list("bisection 2 count one",
269 counted, nr, list);
270 }
271 /*
272 * otherwise, it is known not to reach any
273 * tree-changing commit and gets weight 0.
274 */
275 break;
276 case 1:
277 weight_set(p, -1);
278 break;
279 default:
280 weight_set(p, -2);
281 break;
282 }
283 }
284
285 show_list("bisection 2 initialize", counted, nr, list);
286
287 /*
288 * If you have only one parent in the resulting set
289 * then you can reach one commit more than that parent
290 * can reach. So we do not have to run the expensive
291 * count_distance() for single strand of pearls.
292 *
293 * However, if you have more than one parents, you cannot
294 * just add their distance and one for yourself, since
295 * they usually reach the same ancestor and you would
296 * end up counting them twice that way.
297 *
298 * So we will first count distance of merges the usual
299 * way, and then fill the blanks using cheaper algorithm.
300 */
301 for (p = list; p; p = p->next) {
302 if (p->item->object.flags & UNINTERESTING)
303 continue;
304 if (weight(p) != -2)
305 continue;
306 weight_set(p, count_distance(p));
307 clear_distance(list);
308
309 /* Does it happen to be at exactly half-way? */
310 if (!find_all && halfway(p, nr))
311 return p;
312 counted++;
313 }
314
315 show_list("bisection 2 count_distance", counted, nr, list);
316
317 while (counted < nr) {
318 for (p = list; p; p = p->next) {
319 struct commit_list *q;
320 unsigned flags = p->item->object.flags;
321
322 if (0 <= weight(p))
323 continue;
324 for (q = p->item->parents; q; q = q->next) {
325 if (q->item->object.flags & UNINTERESTING)
326 continue;
327 if (0 <= weight(q))
328 break;
329 }
330 if (!q)
331 continue;
332
333 /*
334 * weight for p is unknown but q is known.
335 * add one for p itself if p is to be counted,
336 * otherwise inherit it from q directly.
337 */
338 if (!(flags & TREESAME)) {
339 weight_set(p, weight(q)+1);
340 counted++;
341 show_list("bisection 2 count one",
342 counted, nr, list);
343 }
344 else
345 weight_set(p, weight(q));
346
347 /* Does it happen to be at exactly half-way? */
348 if (!find_all && halfway(p, nr))
349 return p;
350 }
351 }
352
353 show_list("bisection 2 counted all", counted, nr, list);
354
355 if (!find_all)
356 return best_bisection(list, nr);
357 else
358 return best_bisection_sorted(list, nr);
359}
360
361struct commit_list *find_bisection(struct commit_list *list,
362 int *reaches, int *all,
363 int find_all)
364{
365 int nr, on_list;
366 struct commit_list *p, *best, *next, *last;
367 int *weights;
368
369 show_list("bisection 2 entry", 0, 0, list);
370
371 /*
372 * Count the number of total and tree-changing items on the
373 * list, while reversing the list.
374 */
375 for (nr = on_list = 0, last = NULL, p = list;
376 p;
377 p = next) {
378 unsigned flags = p->item->object.flags;
379
380 next = p->next;
381 if (flags & UNINTERESTING)
382 continue;
383 p->next = last;
384 last = p;
385 if (!(flags & TREESAME))
386 nr++;
387 on_list++;
388 }
389 list = last;
390 show_list("bisection 2 sorted", 0, nr, list);
391
392 *all = nr;
393 weights = xcalloc(on_list, sizeof(*weights));
394
395 /* Do the real work of finding bisection commit. */
396 best = do_find_bisection(list, nr, weights, find_all);
397 if (best) {
398 if (!find_all)
399 best->next = NULL;
400 *reaches = weight(best);
401 }
402 free(weights);
403 return best;
404}
405
eed25148 406static int register_ref(const char *refname, const struct object_id *oid,
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407 int flags, void *cb_data)
408{
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409 struct strbuf good_prefix = STRBUF_INIT;
410 strbuf_addstr(&good_prefix, term_good);
411 strbuf_addstr(&good_prefix, "-");
412
413 if (!strcmp(refname, term_bad)) {
3c5ff995 414 current_bad_oid = xmalloc(sizeof(*current_bad_oid));
eed25148 415 oidcpy(current_bad_oid, oid);
43f9d9f3 416 } else if (starts_with(refname, good_prefix.buf)) {
eed25148 417 sha1_array_append(&good_revs, oid->hash);
59556548 418 } else if (starts_with(refname, "skip-")) {
eed25148 419 sha1_array_append(&skipped_revs, oid->hash);
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420 }
421
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422 strbuf_release(&good_prefix);
423
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424 return 0;
425}
426
427static int read_bisect_refs(void)
428{
eed25148 429 return for_each_ref_in("refs/bisect/", register_ref, NULL);
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430}
431
2af202be 432static void read_bisect_paths(struct argv_array *array)
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433{
434 struct strbuf str = STRBUF_INIT;
435 const char *filename = git_path("BISECT_NAMES");
436 FILE *fp = fopen(filename, "r");
437
438 if (!fp)
d824cbba 439 die_errno("Could not open file '%s'", filename);
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440
441 while (strbuf_getline(&str, fp, '\n') != EOF) {
3b437b0d 442 strbuf_trim(&str);
8a534b61 443 if (sq_dequote_to_argv_array(str.buf, array))
3b437b0d 444 die("Badly quoted content in file '%s': %s",
8a534b61 445 filename, str.buf);
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446 }
447
448 strbuf_release(&str);
449 fclose(fp);
450}
451
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452static char *join_sha1_array_hex(struct sha1_array *array, char delim)
453{
454 struct strbuf joined_hexs = STRBUF_INIT;
455 int i;
456
902bb364 457 for (i = 0; i < array->nr; i++) {
c0537662 458 strbuf_addstr(&joined_hexs, sha1_to_hex(array->sha1[i]));
902bb364 459 if (i + 1 < array->nr)
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460 strbuf_addch(&joined_hexs, delim);
461 }
462
463 return strbuf_detach(&joined_hexs, NULL);
464}
465
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466/*
467 * In this function, passing a not NULL skipped_first is very special.
468 * It means that we want to know if the first commit in the list is
469 * skipped because we will want to test a commit away from it if it is
470 * indeed skipped.
471 * So if the first commit is skipped, we cannot take the shortcut to
472 * just "return list" when we find the first non skipped commit, we
473 * have to return a fully filtered list.
474 *
475 * We use (*skipped_first == -1) to mean "it has been found that the
476 * first commit is not skipped". In this case *skipped_first is set back
477 * to 0 just before the function returns.
478 */
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479struct commit_list *filter_skipped(struct commit_list *list,
480 struct commit_list **tried,
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481 int show_all,
482 int *count,
483 int *skipped_first)
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484{
485 struct commit_list *filtered = NULL, **f = &filtered;
486
487 *tried = NULL;
488
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489 if (skipped_first)
490 *skipped_first = 0;
491 if (count)
492 *count = 0;
493
902bb364 494 if (!skipped_revs.nr)
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495 return list;
496
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497 while (list) {
498 struct commit_list *next = list->next;
499 list->next = NULL;
902bb364 500 if (0 <= sha1_array_lookup(&skipped_revs,
aaaff9e2 501 list->item->object.sha1)) {
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502 if (skipped_first && !*skipped_first)
503 *skipped_first = 1;
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504 /* Move current to tried list */
505 *tried = list;
506 tried = &list->next;
507 } else {
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508 if (!show_all) {
509 if (!skipped_first || !*skipped_first)
510 return list;
511 } else if (skipped_first && !*skipped_first) {
512 /* This means we know it's not skipped */
513 *skipped_first = -1;
514 }
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515 /* Move current to filtered list */
516 *f = list;
517 f = &list->next;
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518 if (count)
519 (*count)++;
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520 }
521 list = next;
522 }
523
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524 if (skipped_first && *skipped_first == -1)
525 *skipped_first = 0;
526
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527 return filtered;
528}
1bf072e3 529
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530#define PRN_MODULO 32768
531
532/*
533 * This is a pseudo random number generator based on "man 3 rand".
534 * It is not used properly because the seed is the argument and it
535 * is increased by one between each call, but that should not matter
536 * for this application.
537 */
7b96d888 538static unsigned get_prn(unsigned count) {
ebc9529f 539 count = count * 1103515245 + 12345;
7b96d888 540 return (count/65536) % PRN_MODULO;
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541}
542
543/*
544 * Custom integer square root from
545 * http://en.wikipedia.org/wiki/Integer_square_root
546 */
547static int sqrti(int val)
548{
549 float d, x = val;
550
551 if (val == 0)
552 return 0;
553
554 do {
555 float y = (x + (float)val / x) / 2;
556 d = (y > x) ? y - x : x - y;
557 x = y;
558 } while (d >= 0.5);
559
560 return (int)x;
561}
562
563static struct commit_list *skip_away(struct commit_list *list, int count)
62d0b0da 564{
62d0b0da 565 struct commit_list *cur, *previous;
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566 int prn, index, i;
567
568 prn = get_prn(count);
569 index = (count * prn / PRN_MODULO) * sqrti(prn) / sqrti(PRN_MODULO);
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570
571 cur = list;
572 previous = NULL;
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573
574 for (i = 0; cur; cur = cur->next, i++) {
575 if (i == index) {
3c5ff995 576 if (hashcmp(cur->item->object.sha1, current_bad_oid->hash))
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577 return cur;
578 if (previous)
579 return previous;
580 return list;
581 }
582 previous = cur;
583 }
584
585 return list;
586}
587
588static struct commit_list *managed_skipped(struct commit_list *list,
589 struct commit_list **tried)
590{
591 int count, skipped_first;
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592
593 *tried = NULL;
594
902bb364 595 if (!skipped_revs.nr)
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596 return list;
597
598 list = filter_skipped(list, tried, 0, &count, &skipped_first);
599
600 if (!skipped_first)
601 return list;
602
ebc9529f 603 return skip_away(list, count);
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604}
605
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606static void bisect_rev_setup(struct rev_info *revs, const char *prefix,
607 const char *bad_format, const char *good_format,
608 int read_paths)
1bf072e3 609{
8a534b61 610 struct argv_array rev_argv = ARGV_ARRAY_INIT;
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611 int i;
612
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613 init_revisions(revs, prefix);
614 revs->abbrev = 0;
615 revs->commit_format = CMIT_FMT_UNSPECIFIED;
1bf072e3 616
1c953a1f 617 /* rev_argv.argv[0] will be ignored by setup_revisions */
8a534b61 618 argv_array_push(&rev_argv, "bisect_rev_setup");
3c5ff995 619 argv_array_pushf(&rev_argv, bad_format, oid_to_hex(current_bad_oid));
902bb364 620 for (i = 0; i < good_revs.nr; i++)
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621 argv_array_pushf(&rev_argv, good_format,
622 sha1_to_hex(good_revs.sha1[i]));
623 argv_array_push(&rev_argv, "--");
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624 if (read_paths)
625 read_bisect_paths(&rev_argv);
3b437b0d 626
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627 setup_revisions(rev_argv.argc, rev_argv.argv, revs, NULL);
628 /* XXX leak rev_argv, as "revs" may still be pointing to it */
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629}
630
a22347c6 631static void bisect_common(struct rev_info *revs)
2ace9727 632{
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633 if (prepare_revision_walk(revs))
634 die("revision walk setup failed");
635 if (revs->tree_objects)
e76a5fb4 636 mark_edges_uninteresting(revs, NULL);
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637}
638
ef24c7ca 639static void exit_if_skipped_commits(struct commit_list *tried,
3c5ff995 640 const struct object_id *bad)
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641{
642 if (!tried)
643 return;
644
645 printf("There are only 'skip'ped commits left to test.\n"
43f9d9f3 646 "The first %s commit could be any of:\n", term_bad);
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647 print_commit_list(tried, "%s\n", "%s\n");
648 if (bad)
3c5ff995 649 printf("%s\n", oid_to_hex(bad));
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650 printf("We cannot bisect more!\n");
651 exit(2);
652}
653
3c5ff995 654static int is_expected_rev(const struct object_id *oid)
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655{
656 const char *filename = git_path("BISECT_EXPECTED_REV");
657 struct stat st;
658 struct strbuf str = STRBUF_INIT;
659 FILE *fp;
660 int res = 0;
661
662 if (stat(filename, &st) || !S_ISREG(st.st_mode))
663 return 0;
664
665 fp = fopen(filename, "r");
666 if (!fp)
667 return 0;
668
669 if (strbuf_getline(&str, fp, '\n') != EOF)
3c5ff995 670 res = !strcmp(str.buf, oid_to_hex(oid));
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671
672 strbuf_release(&str);
673 fclose(fp);
674
675 return res;
676}
677
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678static void mark_expected_rev(char *bisect_rev_hex)
679{
680 int len = strlen(bisect_rev_hex);
681 const char *filename = git_path("BISECT_EXPECTED_REV");
682 int fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
683
684 if (fd < 0)
d824cbba 685 die_errno("could not create file '%s'", filename);
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686
687 bisect_rev_hex[len] = '\n';
688 write_or_die(fd, bisect_rev_hex, len + 1);
689 bisect_rev_hex[len] = '\0';
690
691 if (close(fd) < 0)
692 die("closing file %s: %s", filename, strerror(errno));
693}
694
fee92fc1 695static int bisect_checkout(char *bisect_rev_hex, int no_checkout)
ef24c7ca 696{
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697
698 mark_expected_rev(bisect_rev_hex);
699
700 argv_checkout[2] = bisect_rev_hex;
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701 if (no_checkout) {
702 argv_update_ref[3] = bisect_rev_hex;
703 if (run_command_v_opt(argv_update_ref, RUN_GIT_CMD))
704 die("update-ref --no-deref HEAD failed on %s",
705 bisect_rev_hex);
706 } else {
4824d1b8 707 int res;
fee92fc1
JS
708 res = run_command_v_opt(argv_checkout, RUN_GIT_CMD);
709 if (res)
710 exit(res);
711 }
ef24c7ca
CC
712
713 argv_show_branch[1] = bisect_rev_hex;
714 return run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
715}
716
c0537662
CC
717static struct commit *get_commit_reference(const unsigned char *sha1)
718{
719 struct commit *r = lookup_commit_reference(sha1);
720 if (!r)
721 die("Not a valid commit name %s", sha1_to_hex(sha1));
722 return r;
723}
724
725static struct commit **get_bad_and_good_commits(int *rev_nr)
726{
902bb364 727 int len = 1 + good_revs.nr;
c0537662
CC
728 struct commit **rev = xmalloc(len * sizeof(*rev));
729 int i, n = 0;
730
3c5ff995 731 rev[n++] = get_commit_reference(current_bad_oid->hash);
902bb364 732 for (i = 0; i < good_revs.nr; i++)
c0537662
CC
733 rev[n++] = get_commit_reference(good_revs.sha1[i]);
734 *rev_nr = n;
735
736 return rev;
737}
738
739static void handle_bad_merge_base(void)
740{
3c5ff995 741 if (is_expected_rev(current_bad_oid)) {
742 char *bad_hex = oid_to_hex(current_bad_oid);
c0537662 743 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
43f9d9f3
AD
744 if (!strcmp(term_bad, "bad") && !strcmp(term_good, "good")) {
745 fprintf(stderr, "The merge base %s is bad.\n"
746 "This means the bug has been fixed "
747 "between %s and [%s].\n",
748 bad_hex, bad_hex, good_hex);
749 } else {
750 fprintf(stderr, "The merge base %s is %s.\n"
751 "This means the first '%s' commit is "
752 "between %s and [%s].\n",
753 bad_hex, term_bad, term_good, bad_hex, good_hex);
754 }
c0537662
CC
755 exit(3);
756 }
757
43f9d9f3 758 fprintf(stderr, "Some %s revs are not ancestor of the %s rev.\n"
c0537662 759 "git bisect cannot work properly in this case.\n"
43f9d9f3
AD
760 "Maybe you mistook %s and %s revs?\n",
761 term_good, term_bad, term_good, term_bad);
c0537662
CC
762 exit(1);
763}
764
2af202be 765static void handle_skipped_merge_base(const unsigned char *mb)
c0537662
CC
766{
767 char *mb_hex = sha1_to_hex(mb);
3c5ff995 768 char *bad_hex = sha1_to_hex(current_bad_oid->hash);
c0537662
CC
769 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
770
bd757c18 771 warning("the merge base between %s and [%s] "
c0537662 772 "must be skipped.\n"
43f9d9f3 773 "So we cannot be sure the first %s commit is "
c0537662 774 "between %s and %s.\n"
bd757c18 775 "We continue anyway.",
43f9d9f3 776 bad_hex, good_hex, term_bad, mb_hex, bad_hex);
c0537662
CC
777 free(good_hex);
778}
779
780/*
781 * "check_merge_bases" checks that merge bases are not "bad".
782 *
783 * - If one is "bad", it means the user assumed something wrong
784 * and we must exit with a non 0 error code.
785 * - If one is "good", that's good, we have nothing to do.
786 * - If one is "skipped", we can't know but we should warn.
787 * - If we don't know, we should check it out and ask the user to test.
788 */
fee92fc1 789static void check_merge_bases(int no_checkout)
c0537662
CC
790{
791 struct commit_list *result;
792 int rev_nr;
793 struct commit **rev = get_bad_and_good_commits(&rev_nr);
794
2ce406cc 795 result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1);
c0537662
CC
796
797 for (; result; result = result->next) {
798 const unsigned char *mb = result->item->object.sha1;
3c5ff995 799 if (!hashcmp(mb, current_bad_oid->hash)) {
c0537662 800 handle_bad_merge_base();
902bb364 801 } else if (0 <= sha1_array_lookup(&good_revs, mb)) {
c0537662 802 continue;
902bb364 803 } else if (0 <= sha1_array_lookup(&skipped_revs, mb)) {
c0537662
CC
804 handle_skipped_merge_base(mb);
805 } else {
806 printf("Bisecting: a merge base must be tested\n");
fee92fc1 807 exit(bisect_checkout(sha1_to_hex(mb), no_checkout));
c0537662
CC
808 }
809 }
810
811 free(rev);
812 free_commit_list(result);
813}
814
2d938fc7 815static int check_ancestors(const char *prefix)
d937d4ac 816{
2d938fc7
CC
817 struct rev_info revs;
818 struct object_array pending_copy;
86a0a408 819 int res;
d937d4ac 820
2d938fc7 821 bisect_rev_setup(&revs, prefix, "^%s", "%s", 0);
d937d4ac 822
2d938fc7 823 /* Save pending objects, so they can be cleaned up later. */
353f5657
RS
824 pending_copy = revs.pending;
825 revs.leak_pending = 1;
2d938fc7 826
353f5657
RS
827 /*
828 * bisect_common calls prepare_revision_walk right away, which
829 * (together with .leak_pending = 1) makes us the sole owner of
830 * the list of pending objects.
831 */
2d938fc7
CC
832 bisect_common(&revs);
833 res = (revs.commits != NULL);
834
835 /* Clean up objects used, as they will be reused. */
86a0a408 836 clear_commit_marks_for_object_array(&pending_copy, ALL_REV_FLAGS);
353f5657 837 free(pending_copy.objects);
d937d4ac 838
2d938fc7 839 return res;
d937d4ac
CC
840}
841
842/*
843 * "check_good_are_ancestors_of_bad" checks that all "good" revs are
844 * ancestor of the "bad" rev.
845 *
846 * If that's not the case, we need to check the merge bases.
847 * If a merge base must be tested by the user, its source code will be
848 * checked out to be tested by the user and we will exit.
849 */
fee92fc1 850static void check_good_are_ancestors_of_bad(const char *prefix, int no_checkout)
d937d4ac 851{
d292bfaf 852 char *filename = git_pathdup("BISECT_ANCESTORS_OK");
d937d4ac
CC
853 struct stat st;
854 int fd;
855
3c5ff995 856 if (!current_bad_oid)
43f9d9f3 857 die("a %s revision is needed", term_bad);
d937d4ac
CC
858
859 /* Check if file BISECT_ANCESTORS_OK exists. */
860 if (!stat(filename, &st) && S_ISREG(st.st_mode))
144e7090 861 goto done;
d937d4ac
CC
862
863 /* Bisecting with no good rev is ok. */
902bb364 864 if (good_revs.nr == 0)
144e7090 865 goto done;
d937d4ac 866
2d938fc7
CC
867 /* Check if all good revs are ancestor of the bad rev. */
868 if (check_ancestors(prefix))
fee92fc1 869 check_merge_bases(no_checkout);
d937d4ac
CC
870
871 /* Create file BISECT_ANCESTORS_OK. */
872 fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
873 if (fd < 0)
874 warning("could not create file '%s': %s",
875 filename, strerror(errno));
876 else
877 close(fd);
144e7090
MH
878 done:
879 free(filename);
d937d4ac
CC
880}
881
e22278c0
CC
882/*
883 * This does "git diff-tree --pretty COMMIT" without one fork+exec.
884 */
885static void show_diff_tree(const char *prefix, struct commit *commit)
886{
887 struct rev_info opt;
888
889 /* diff-tree init */
890 init_revisions(&opt, prefix);
891 git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
892 opt.abbrev = 0;
893 opt.diff = 1;
894
895 /* This is what "--pretty" does */
896 opt.verbose_header = 1;
897 opt.use_terminator = 0;
898 opt.commit_format = CMIT_FMT_DEFAULT;
899
900 /* diff-tree init */
901 if (!opt.diffopt.output_format)
902 opt.diffopt.output_format = DIFF_FORMAT_RAW;
903
904 log_tree_commit(&opt, commit);
905}
906
ef24c7ca
CC
907/*
908 * We use the convention that exiting with an exit code 10 means that
909 * the bisection process finished successfully.
910 * In this case the calling shell script should exit 0.
fee92fc1
JS
911 *
912 * If no_checkout is non-zero, the bisection process does not
913 * checkout the trial commit but instead simply updates BISECT_HEAD.
ef24c7ca 914 */
fee92fc1 915int bisect_next_all(const char *prefix, int no_checkout)
ef24c7ca
CC
916{
917 struct rev_info revs;
918 struct commit_list *tried;
6329bade 919 int reaches = 0, all = 0, nr, steps;
ef24c7ca 920 const unsigned char *bisect_rev;
3c5ff995 921 char bisect_rev_hex[GIT_SHA1_HEXSZ + 1];
ef24c7ca 922
43f9d9f3
AD
923 term_bad = "bad";
924 term_good = "good";
2b020695
CC
925 if (read_bisect_refs())
926 die("reading bisect refs failed");
927
fee92fc1 928 check_good_are_ancestors_of_bad(prefix, no_checkout);
0871984d 929
a22347c6
CC
930 bisect_rev_setup(&revs, prefix, "%s", "^%s", 1);
931 revs.limited = 1;
2b020695 932
a22347c6 933 bisect_common(&revs);
ef24c7ca 934
a22347c6 935 revs.commits = find_bisection(revs.commits, &reaches, &all,
902bb364 936 !!skipped_revs.nr);
62d0b0da 937 revs.commits = managed_skipped(revs.commits, &tried);
ef24c7ca
CC
938
939 if (!revs.commits) {
940 /*
941 * We should exit here only if the "bad"
942 * commit is also a "skip" commit.
943 */
944 exit_if_skipped_commits(tried, NULL);
945
43f9d9f3
AD
946 printf("%s was both %s and %s\n",
947 oid_to_hex(current_bad_oid),
948 term_good,
949 term_bad);
ef24c7ca
CC
950 exit(1);
951 }
952
8f69f72f
CC
953 if (!all) {
954 fprintf(stderr, "No testable commit found.\n"
955 "Maybe you started with bad path parameters?\n");
956 exit(4);
957 }
958
ef24c7ca 959 bisect_rev = revs.commits->item->object.sha1;
3c5ff995 960 memcpy(bisect_rev_hex, sha1_to_hex(bisect_rev), GIT_SHA1_HEXSZ + 1);
ef24c7ca 961
3c5ff995 962 if (!hashcmp(bisect_rev, current_bad_oid->hash)) {
963 exit_if_skipped_commits(tried, current_bad_oid);
43f9d9f3
AD
964 printf("%s is the first %s commit\n", bisect_rev_hex,
965 term_bad);
e22278c0 966 show_diff_tree(prefix, revs.commits->item);
ef24c7ca
CC
967 /* This means the bisection process succeeded. */
968 exit(10);
969 }
970
971 nr = all - reaches - 1;
6329bade
DR
972 steps = estimate_bisect_steps(all);
973 printf("Bisecting: %d revision%s left to test after this "
974 "(roughly %d step%s)\n", nr, (nr == 1 ? "" : "s"),
975 steps, (steps == 1 ? "" : "s"));
ef24c7ca 976
fee92fc1 977 return bisect_checkout(bisect_rev_hex, no_checkout);
ef24c7ca
CC
978}
979
c43cb386
NTND
980static inline int log2i(int n)
981{
982 int log2 = 0;
983
984 for (; n > 1; n >>= 1)
985 log2++;
986
987 return log2;
988}
989
990static inline int exp2i(int n)
991{
992 return 1 << n;
993}
994
995/*
996 * Estimate the number of bisect steps left (after the current step)
997 *
998 * For any x between 0 included and 2^n excluded, the probability for
999 * n - 1 steps left looks like:
1000 *
1001 * P(2^n + x) == (2^n - x) / (2^n + x)
1002 *
1003 * and P(2^n + x) < 0.5 means 2^n < 3x
1004 */
1005int estimate_bisect_steps(int all)
1006{
1007 int n, x, e;
1008
1009 if (all < 3)
1010 return 0;
1011
1012 n = log2i(all);
1013 e = exp2i(n);
1014 x = all - e;
1015
1016 return (e < 3 * x) ? n : n - 1;
1017}