strbuf: introduce strbuf_getline_{lf,nul}()
[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};
22
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23static const char *term_bad;
24static const char *term_good;
25
208acbfb 26/* Remember to update object flag allocation in object.h */
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27#define COUNTED (1u<<16)
28
29/*
30 * This is a truly stupid algorithm, but it's only
31 * used for bisection, and we just don't care enough.
32 *
33 * We care just barely enough to avoid recursing for
34 * non-merge entries.
35 */
36static int count_distance(struct commit_list *entry)
37{
38 int nr = 0;
39
40 while (entry) {
41 struct commit *commit = entry->item;
42 struct commit_list *p;
43
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;
56 }
57 }
58 }
59
60 return nr;
61}
62
63static void clear_distance(struct commit_list *list)
64{
65 while (list) {
66 struct commit *commit = list->item;
67 commit->object.flags &= ~COUNTED;
68 list = list->next;
69 }
70}
71
72#define DEBUG_BISECT 0
73
74static inline int weight(struct commit_list *elem)
75{
76 return *((int*)(elem->item->util));
77}
78
79static inline void weight_set(struct commit_list *elem, int weight)
80{
81 *((int*)(elem->item->util)) = weight;
82}
83
84static int count_interesting_parents(struct commit *commit)
85{
86 struct commit_list *p;
87 int count;
88
89 for (count = 0, p = commit->parents; p; p = p->next) {
90 if (p->item->object.flags & UNINTERESTING)
91 continue;
92 count++;
93 }
94 return count;
95}
96
97static inline int halfway(struct commit_list *p, int nr)
98{
99 /*
100 * Don't short-cut something we are not going to return!
101 */
102 if (p->item->object.flags & TREESAME)
103 return 0;
104 if (DEBUG_BISECT)
105 return 0;
106 /*
107 * 2 and 3 are halfway of 5.
108 * 3 is halfway of 6 but 2 and 4 are not.
109 */
110 switch (2 * weight(p) - nr) {
111 case -1: case 0: case 1:
112 return 1;
113 default:
114 return 0;
115 }
116}
117
118#if !DEBUG_BISECT
119#define show_list(a,b,c,d) do { ; } while (0)
120#else
121static void show_list(const char *debug, int counted, int nr,
122 struct commit_list *list)
123{
124 struct commit_list *p;
125
126 fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr);
127
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);
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135 const char *subject_start;
136 int subject_len;
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137
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));
150
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151 subject_len = find_commit_subject(buf, &subject_start);
152 if (subject_len)
153 fprintf(stderr, " %.*s", subject_len, subject_start);
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154 fprintf(stderr, "\n");
155 }
156}
157#endif /* DEBUG_BISECT */
158
159static struct commit_list *best_bisection(struct commit_list *list, int nr)
160{
161 struct commit_list *p, *best;
162 int best_distance = -1;
163
164 best = list;
165 for (p = list; p; p = p->next) {
166 int distance;
167 unsigned flags = p->item->object.flags;
168
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;
177 }
178 }
179
180 return best;
181}
182
183struct commit_dist {
184 struct commit *commit;
185 int distance;
186};
187
188static int compare_commit_dist(const void *a_, const void *b_)
189{
190 struct commit_dist *a, *b;
191
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 */
f2fd0760 196 return oidcmp(&a->commit->object.oid, &b->commit->object.oid);
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197}
198
199static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
200{
201 struct commit_list *p;
202 struct commit_dist *array = xcalloc(nr, sizeof(*array));
203 int cnt, i;
204
205 for (p = list, cnt = 0; p; p = p->next) {
206 int distance;
207 unsigned flags = p->item->object.flags;
208
209 if (flags & TREESAME)
210 continue;
211 distance = weight(p);
212 if (nr - distance < distance)
213 distance = nr - distance;
214 array[cnt].commit = p->item;
215 array[cnt].distance = distance;
216 cnt++;
217 }
218 qsort(array, cnt, sizeof(*array), compare_commit_dist);
219 for (p = list, i = 0; i < cnt; i++) {
662174d2 220 char buf[100]; /* enough for dist=%d */
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221 struct object *obj = &(array[i].commit->object);
222
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223 snprintf(buf, sizeof(buf), "dist=%d", array[i].distance);
224 add_name_decoration(DECORATION_NONE, buf, obj);
225
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226 p->item = array[i].commit;
227 p = p->next;
228 }
229 if (p)
230 p->next = NULL;
231 free(array);
232 return list;
233}
234
235/*
236 * zero or positive weight is the number of interesting commits it can
237 * reach, including itself. Especially, weight = 0 means it does not
238 * reach any tree-changing commits (e.g. just above uninteresting one
239 * but traversal is with pathspec).
240 *
241 * weight = -1 means it has one parent and its distance is yet to
242 * be computed.
243 *
244 * weight = -2 means it has more than one parent and its distance is
245 * unknown. After running count_distance() first, they will get zero
246 * or positive distance.
247 */
248static struct commit_list *do_find_bisection(struct commit_list *list,
249 int nr, int *weights,
250 int find_all)
251{
252 int n, counted;
253 struct commit_list *p;
254
255 counted = 0;
256
257 for (n = 0, p = list; p; p = p->next) {
258 struct commit *commit = p->item;
259 unsigned flags = commit->object.flags;
260
261 p->item->util = &weights[n++];
262 switch (count_interesting_parents(commit)) {
263 case 0:
264 if (!(flags & TREESAME)) {
265 weight_set(p, 1);
266 counted++;
267 show_list("bisection 2 count one",
268 counted, nr, list);
269 }
270 /*
271 * otherwise, it is known not to reach any
272 * tree-changing commit and gets weight 0.
273 */
274 break;
275 case 1:
276 weight_set(p, -1);
277 break;
278 default:
279 weight_set(p, -2);
280 break;
281 }
282 }
283
284 show_list("bisection 2 initialize", counted, nr, list);
285
286 /*
287 * If you have only one parent in the resulting set
288 * then you can reach one commit more than that parent
289 * can reach. So we do not have to run the expensive
290 * count_distance() for single strand of pearls.
291 *
292 * However, if you have more than one parents, you cannot
293 * just add their distance and one for yourself, since
294 * they usually reach the same ancestor and you would
295 * end up counting them twice that way.
296 *
297 * So we will first count distance of merges the usual
298 * way, and then fill the blanks using cheaper algorithm.
299 */
300 for (p = list; p; p = p->next) {
301 if (p->item->object.flags & UNINTERESTING)
302 continue;
303 if (weight(p) != -2)
304 continue;
305 weight_set(p, count_distance(p));
306 clear_distance(list);
307
308 /* Does it happen to be at exactly half-way? */
309 if (!find_all && halfway(p, nr))
310 return p;
311 counted++;
312 }
313
314 show_list("bisection 2 count_distance", counted, nr, list);
315
316 while (counted < nr) {
317 for (p = list; p; p = p->next) {
318 struct commit_list *q;
319 unsigned flags = p->item->object.flags;
320
321 if (0 <= weight(p))
322 continue;
323 for (q = p->item->parents; q; q = q->next) {
324 if (q->item->object.flags & UNINTERESTING)
325 continue;
326 if (0 <= weight(q))
327 break;
328 }
329 if (!q)
330 continue;
331
332 /*
333 * weight for p is unknown but q is known.
334 * add one for p itself if p is to be counted,
335 * otherwise inherit it from q directly.
336 */
337 if (!(flags & TREESAME)) {
338 weight_set(p, weight(q)+1);
339 counted++;
340 show_list("bisection 2 count one",
341 counted, nr, list);
342 }
343 else
344 weight_set(p, weight(q));
345
346 /* Does it happen to be at exactly half-way? */
347 if (!find_all && halfway(p, nr))
348 return p;
349 }
350 }
351
352 show_list("bisection 2 counted all", counted, nr, list);
353
354 if (!find_all)
355 return best_bisection(list, nr);
356 else
357 return best_bisection_sorted(list, nr);
358}
359
360struct commit_list *find_bisection(struct commit_list *list,
361 int *reaches, int *all,
362 int find_all)
363{
364 int nr, on_list;
365 struct commit_list *p, *best, *next, *last;
366 int *weights;
367
368 show_list("bisection 2 entry", 0, 0, list);
369
370 /*
371 * Count the number of total and tree-changing items on the
372 * list, while reversing the list.
373 */
374 for (nr = on_list = 0, last = NULL, p = list;
375 p;
376 p = next) {
377 unsigned flags = p->item->object.flags;
378
379 next = p->next;
380 if (flags & UNINTERESTING)
381 continue;
382 p->next = last;
383 last = p;
384 if (!(flags & TREESAME))
385 nr++;
386 on_list++;
387 }
388 list = last;
389 show_list("bisection 2 sorted", 0, nr, list);
390
391 *all = nr;
392 weights = xcalloc(on_list, sizeof(*weights));
393
394 /* Do the real work of finding bisection commit. */
395 best = do_find_bisection(list, nr, weights, find_all);
396 if (best) {
397 if (!find_all)
398 best->next = NULL;
399 *reaches = weight(best);
400 }
401 free(weights);
402 return best;
403}
404
eed25148 405static int register_ref(const char *refname, const struct object_id *oid,
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406 int flags, void *cb_data)
407{
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408 struct strbuf good_prefix = STRBUF_INIT;
409 strbuf_addstr(&good_prefix, term_good);
410 strbuf_addstr(&good_prefix, "-");
411
412 if (!strcmp(refname, term_bad)) {
3c5ff995 413 current_bad_oid = xmalloc(sizeof(*current_bad_oid));
eed25148 414 oidcpy(current_bad_oid, oid);
43f9d9f3 415 } else if (starts_with(refname, good_prefix.buf)) {
eed25148 416 sha1_array_append(&good_revs, oid->hash);
59556548 417 } else if (starts_with(refname, "skip-")) {
eed25148 418 sha1_array_append(&skipped_revs, oid->hash);
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419 }
420
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421 strbuf_release(&good_prefix);
422
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423 return 0;
424}
425
426static int read_bisect_refs(void)
427{
eed25148 428 return for_each_ref_in("refs/bisect/", register_ref, NULL);
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429}
430
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431static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
432static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")
433
2af202be 434static void read_bisect_paths(struct argv_array *array)
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435{
436 struct strbuf str = STRBUF_INIT;
f932729c 437 const char *filename = git_path_bisect_names();
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438 FILE *fp = fopen(filename, "r");
439
440 if (!fp)
d824cbba 441 die_errno("Could not open file '%s'", filename);
3b437b0d 442
8f309aeb 443 while (strbuf_getline_lf(&str, fp) != EOF) {
3b437b0d 444 strbuf_trim(&str);
8a534b61 445 if (sq_dequote_to_argv_array(str.buf, array))
3b437b0d 446 die("Badly quoted content in file '%s': %s",
8a534b61 447 filename, str.buf);
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448 }
449
450 strbuf_release(&str);
451 fclose(fp);
452}
453
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454static char *join_sha1_array_hex(struct sha1_array *array, char delim)
455{
456 struct strbuf joined_hexs = STRBUF_INIT;
457 int i;
458
902bb364 459 for (i = 0; i < array->nr; i++) {
c0537662 460 strbuf_addstr(&joined_hexs, sha1_to_hex(array->sha1[i]));
902bb364 461 if (i + 1 < array->nr)
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462 strbuf_addch(&joined_hexs, delim);
463 }
464
465 return strbuf_detach(&joined_hexs, NULL);
466}
467
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468/*
469 * In this function, passing a not NULL skipped_first is very special.
470 * It means that we want to know if the first commit in the list is
471 * skipped because we will want to test a commit away from it if it is
472 * indeed skipped.
473 * So if the first commit is skipped, we cannot take the shortcut to
474 * just "return list" when we find the first non skipped commit, we
475 * have to return a fully filtered list.
476 *
477 * We use (*skipped_first == -1) to mean "it has been found that the
478 * first commit is not skipped". In this case *skipped_first is set back
479 * to 0 just before the function returns.
480 */
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481struct commit_list *filter_skipped(struct commit_list *list,
482 struct commit_list **tried,
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483 int show_all,
484 int *count,
485 int *skipped_first)
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486{
487 struct commit_list *filtered = NULL, **f = &filtered;
488
489 *tried = NULL;
490
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491 if (skipped_first)
492 *skipped_first = 0;
493 if (count)
494 *count = 0;
495
902bb364 496 if (!skipped_revs.nr)
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497 return list;
498
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499 while (list) {
500 struct commit_list *next = list->next;
501 list->next = NULL;
902bb364 502 if (0 <= sha1_array_lookup(&skipped_revs,
ed1c9977 503 list->item->object.oid.hash)) {
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504 if (skipped_first && !*skipped_first)
505 *skipped_first = 1;
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506 /* Move current to tried list */
507 *tried = list;
508 tried = &list->next;
509 } else {
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510 if (!show_all) {
511 if (!skipped_first || !*skipped_first)
512 return list;
513 } else if (skipped_first && !*skipped_first) {
514 /* This means we know it's not skipped */
515 *skipped_first = -1;
516 }
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517 /* Move current to filtered list */
518 *f = list;
519 f = &list->next;
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520 if (count)
521 (*count)++;
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522 }
523 list = next;
524 }
525
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526 if (skipped_first && *skipped_first == -1)
527 *skipped_first = 0;
528
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529 return filtered;
530}
1bf072e3 531
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532#define PRN_MODULO 32768
533
534/*
535 * This is a pseudo random number generator based on "man 3 rand".
536 * It is not used properly because the seed is the argument and it
537 * is increased by one between each call, but that should not matter
538 * for this application.
539 */
7b96d888 540static unsigned get_prn(unsigned count) {
ebc9529f 541 count = count * 1103515245 + 12345;
7b96d888 542 return (count/65536) % PRN_MODULO;
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543}
544
545/*
546 * Custom integer square root from
547 * http://en.wikipedia.org/wiki/Integer_square_root
548 */
549static int sqrti(int val)
550{
551 float d, x = val;
552
553 if (val == 0)
554 return 0;
555
556 do {
557 float y = (x + (float)val / x) / 2;
558 d = (y > x) ? y - x : x - y;
559 x = y;
560 } while (d >= 0.5);
561
562 return (int)x;
563}
564
565static struct commit_list *skip_away(struct commit_list *list, int count)
62d0b0da 566{
62d0b0da 567 struct commit_list *cur, *previous;
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568 int prn, index, i;
569
570 prn = get_prn(count);
571 index = (count * prn / PRN_MODULO) * sqrti(prn) / sqrti(PRN_MODULO);
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572
573 cur = list;
574 previous = NULL;
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575
576 for (i = 0; cur; cur = cur->next, i++) {
577 if (i == index) {
f2fd0760 578 if (oidcmp(&cur->item->object.oid, current_bad_oid))
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579 return cur;
580 if (previous)
581 return previous;
582 return list;
583 }
584 previous = cur;
585 }
586
587 return list;
588}
589
590static struct commit_list *managed_skipped(struct commit_list *list,
591 struct commit_list **tried)
592{
593 int count, skipped_first;
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594
595 *tried = NULL;
596
902bb364 597 if (!skipped_revs.nr)
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598 return list;
599
600 list = filter_skipped(list, tried, 0, &count, &skipped_first);
601
602 if (!skipped_first)
603 return list;
604
ebc9529f 605 return skip_away(list, count);
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606}
607
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608static void bisect_rev_setup(struct rev_info *revs, const char *prefix,
609 const char *bad_format, const char *good_format,
610 int read_paths)
1bf072e3 611{
8a534b61 612 struct argv_array rev_argv = ARGV_ARRAY_INIT;
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613 int i;
614
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615 init_revisions(revs, prefix);
616 revs->abbrev = 0;
617 revs->commit_format = CMIT_FMT_UNSPECIFIED;
1bf072e3 618
1c953a1f 619 /* rev_argv.argv[0] will be ignored by setup_revisions */
8a534b61 620 argv_array_push(&rev_argv, "bisect_rev_setup");
3c5ff995 621 argv_array_pushf(&rev_argv, bad_format, oid_to_hex(current_bad_oid));
902bb364 622 for (i = 0; i < good_revs.nr; i++)
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623 argv_array_pushf(&rev_argv, good_format,
624 sha1_to_hex(good_revs.sha1[i]));
625 argv_array_push(&rev_argv, "--");
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626 if (read_paths)
627 read_bisect_paths(&rev_argv);
3b437b0d 628
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629 setup_revisions(rev_argv.argc, rev_argv.argv, revs, NULL);
630 /* XXX leak rev_argv, as "revs" may still be pointing to it */
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631}
632
a22347c6 633static void bisect_common(struct rev_info *revs)
2ace9727 634{
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635 if (prepare_revision_walk(revs))
636 die("revision walk setup failed");
637 if (revs->tree_objects)
e76a5fb4 638 mark_edges_uninteresting(revs, NULL);
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639}
640
ef24c7ca 641static void exit_if_skipped_commits(struct commit_list *tried,
3c5ff995 642 const struct object_id *bad)
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CC
643{
644 if (!tried)
645 return;
646
647 printf("There are only 'skip'ped commits left to test.\n"
43f9d9f3 648 "The first %s commit could be any of:\n", term_bad);
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649 print_commit_list(tried, "%s\n", "%s\n");
650 if (bad)
3c5ff995 651 printf("%s\n", oid_to_hex(bad));
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652 printf("We cannot bisect more!\n");
653 exit(2);
654}
655
3c5ff995 656static int is_expected_rev(const struct object_id *oid)
c0537662 657{
f932729c 658 const char *filename = git_path_bisect_expected_rev();
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CC
659 struct stat st;
660 struct strbuf str = STRBUF_INIT;
661 FILE *fp;
662 int res = 0;
663
664 if (stat(filename, &st) || !S_ISREG(st.st_mode))
665 return 0;
666
667 fp = fopen(filename, "r");
668 if (!fp)
669 return 0;
670
8f309aeb 671 if (strbuf_getline_lf(&str, fp) != EOF)
3c5ff995 672 res = !strcmp(str.buf, oid_to_hex(oid));
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673
674 strbuf_release(&str);
675 fclose(fp);
676
677 return res;
678}
679
f3a97718 680static int bisect_checkout(const unsigned char *bisect_rev, int no_checkout)
ef24c7ca 681{
f3a97718 682 char bisect_rev_hex[GIT_SHA1_HEXSZ + 1];
ef24c7ca 683
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684 memcpy(bisect_rev_hex, sha1_to_hex(bisect_rev), GIT_SHA1_HEXSZ + 1);
685 update_ref(NULL, "BISECT_EXPECTED_REV", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
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686
687 argv_checkout[2] = bisect_rev_hex;
fee92fc1 688 if (no_checkout) {
f3a97718 689 update_ref(NULL, "BISECT_HEAD", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
fee92fc1 690 } else {
4824d1b8 691 int res;
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692 res = run_command_v_opt(argv_checkout, RUN_GIT_CMD);
693 if (res)
694 exit(res);
695 }
ef24c7ca
CC
696
697 argv_show_branch[1] = bisect_rev_hex;
698 return run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
699}
700
c0537662
CC
701static struct commit *get_commit_reference(const unsigned char *sha1)
702{
703 struct commit *r = lookup_commit_reference(sha1);
704 if (!r)
705 die("Not a valid commit name %s", sha1_to_hex(sha1));
706 return r;
707}
708
709static struct commit **get_bad_and_good_commits(int *rev_nr)
710{
902bb364 711 int len = 1 + good_revs.nr;
c0537662
CC
712 struct commit **rev = xmalloc(len * sizeof(*rev));
713 int i, n = 0;
714
3c5ff995 715 rev[n++] = get_commit_reference(current_bad_oid->hash);
902bb364 716 for (i = 0; i < good_revs.nr; i++)
c0537662
CC
717 rev[n++] = get_commit_reference(good_revs.sha1[i]);
718 *rev_nr = n;
719
720 return rev;
721}
722
723static void handle_bad_merge_base(void)
724{
3c5ff995 725 if (is_expected_rev(current_bad_oid)) {
726 char *bad_hex = oid_to_hex(current_bad_oid);
c0537662 727 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
43f9d9f3
AD
728 if (!strcmp(term_bad, "bad") && !strcmp(term_good, "good")) {
729 fprintf(stderr, "The merge base %s is bad.\n"
730 "This means the bug has been fixed "
731 "between %s and [%s].\n",
732 bad_hex, bad_hex, good_hex);
21e5cfd8
AD
733 } else if (!strcmp(term_bad, "new") && !strcmp(term_good, "old")) {
734 fprintf(stderr, "The merge base %s is new.\n"
735 "The property has changed "
736 "between %s and [%s].\n",
737 bad_hex, bad_hex, good_hex);
43f9d9f3
AD
738 } else {
739 fprintf(stderr, "The merge base %s is %s.\n"
740 "This means the first '%s' commit is "
741 "between %s and [%s].\n",
742 bad_hex, term_bad, term_good, bad_hex, good_hex);
743 }
c0537662
CC
744 exit(3);
745 }
746
43f9d9f3 747 fprintf(stderr, "Some %s revs are not ancestor of the %s rev.\n"
c0537662 748 "git bisect cannot work properly in this case.\n"
43f9d9f3
AD
749 "Maybe you mistook %s and %s revs?\n",
750 term_good, term_bad, term_good, term_bad);
c0537662
CC
751 exit(1);
752}
753
2af202be 754static void handle_skipped_merge_base(const unsigned char *mb)
c0537662
CC
755{
756 char *mb_hex = sha1_to_hex(mb);
3c5ff995 757 char *bad_hex = sha1_to_hex(current_bad_oid->hash);
c0537662
CC
758 char *good_hex = join_sha1_array_hex(&good_revs, ' ');
759
bd757c18 760 warning("the merge base between %s and [%s] "
c0537662 761 "must be skipped.\n"
43f9d9f3 762 "So we cannot be sure the first %s commit is "
c0537662 763 "between %s and %s.\n"
bd757c18 764 "We continue anyway.",
43f9d9f3 765 bad_hex, good_hex, term_bad, mb_hex, bad_hex);
c0537662
CC
766 free(good_hex);
767}
768
769/*
21e5cfd8 770 * "check_merge_bases" checks that merge bases are not "bad" (or "new").
c0537662 771 *
21e5cfd8 772 * - If one is "bad" (or "new"), it means the user assumed something wrong
c0537662 773 * and we must exit with a non 0 error code.
21e5cfd8 774 * - If one is "good" (or "old"), that's good, we have nothing to do.
c0537662
CC
775 * - If one is "skipped", we can't know but we should warn.
776 * - If we don't know, we should check it out and ask the user to test.
777 */
fee92fc1 778static void check_merge_bases(int no_checkout)
c0537662
CC
779{
780 struct commit_list *result;
781 int rev_nr;
782 struct commit **rev = get_bad_and_good_commits(&rev_nr);
783
2ce406cc 784 result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1);
c0537662
CC
785
786 for (; result; result = result->next) {
ed1c9977 787 const unsigned char *mb = result->item->object.oid.hash;
3c5ff995 788 if (!hashcmp(mb, current_bad_oid->hash)) {
c0537662 789 handle_bad_merge_base();
902bb364 790 } else if (0 <= sha1_array_lookup(&good_revs, mb)) {
c0537662 791 continue;
902bb364 792 } else if (0 <= sha1_array_lookup(&skipped_revs, mb)) {
c0537662
CC
793 handle_skipped_merge_base(mb);
794 } else {
795 printf("Bisecting: a merge base must be tested\n");
f3a97718 796 exit(bisect_checkout(mb, no_checkout));
c0537662
CC
797 }
798 }
799
800 free(rev);
801 free_commit_list(result);
802}
803
2d938fc7 804static int check_ancestors(const char *prefix)
d937d4ac 805{
2d938fc7
CC
806 struct rev_info revs;
807 struct object_array pending_copy;
86a0a408 808 int res;
d937d4ac 809
2d938fc7 810 bisect_rev_setup(&revs, prefix, "^%s", "%s", 0);
d937d4ac 811
2d938fc7 812 /* Save pending objects, so they can be cleaned up later. */
353f5657
RS
813 pending_copy = revs.pending;
814 revs.leak_pending = 1;
2d938fc7 815
353f5657
RS
816 /*
817 * bisect_common calls prepare_revision_walk right away, which
818 * (together with .leak_pending = 1) makes us the sole owner of
819 * the list of pending objects.
820 */
2d938fc7
CC
821 bisect_common(&revs);
822 res = (revs.commits != NULL);
823
824 /* Clean up objects used, as they will be reused. */
86a0a408 825 clear_commit_marks_for_object_array(&pending_copy, ALL_REV_FLAGS);
353f5657 826 free(pending_copy.objects);
d937d4ac 827
2d938fc7 828 return res;
d937d4ac
CC
829}
830
831/*
832 * "check_good_are_ancestors_of_bad" checks that all "good" revs are
833 * ancestor of the "bad" rev.
834 *
835 * If that's not the case, we need to check the merge bases.
836 * If a merge base must be tested by the user, its source code will be
837 * checked out to be tested by the user and we will exit.
838 */
fee92fc1 839static void check_good_are_ancestors_of_bad(const char *prefix, int no_checkout)
d937d4ac 840{
d292bfaf 841 char *filename = git_pathdup("BISECT_ANCESTORS_OK");
d937d4ac
CC
842 struct stat st;
843 int fd;
844
3c5ff995 845 if (!current_bad_oid)
43f9d9f3 846 die("a %s revision is needed", term_bad);
d937d4ac
CC
847
848 /* Check if file BISECT_ANCESTORS_OK exists. */
849 if (!stat(filename, &st) && S_ISREG(st.st_mode))
144e7090 850 goto done;
d937d4ac
CC
851
852 /* Bisecting with no good rev is ok. */
902bb364 853 if (good_revs.nr == 0)
144e7090 854 goto done;
d937d4ac 855
2d938fc7
CC
856 /* Check if all good revs are ancestor of the bad rev. */
857 if (check_ancestors(prefix))
fee92fc1 858 check_merge_bases(no_checkout);
d937d4ac
CC
859
860 /* Create file BISECT_ANCESTORS_OK. */
861 fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
862 if (fd < 0)
863 warning("could not create file '%s': %s",
864 filename, strerror(errno));
865 else
866 close(fd);
144e7090
MH
867 done:
868 free(filename);
d937d4ac
CC
869}
870
e22278c0
CC
871/*
872 * This does "git diff-tree --pretty COMMIT" without one fork+exec.
873 */
874static void show_diff_tree(const char *prefix, struct commit *commit)
875{
876 struct rev_info opt;
877
878 /* diff-tree init */
879 init_revisions(&opt, prefix);
880 git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
881 opt.abbrev = 0;
882 opt.diff = 1;
883
884 /* This is what "--pretty" does */
885 opt.verbose_header = 1;
886 opt.use_terminator = 0;
887 opt.commit_format = CMIT_FMT_DEFAULT;
888
889 /* diff-tree init */
890 if (!opt.diffopt.output_format)
891 opt.diffopt.output_format = DIFF_FORMAT_RAW;
892
893 log_tree_commit(&opt, commit);
894}
895
cb46d630
AD
896/*
897 * The terms used for this bisect session are stored in BISECT_TERMS.
898 * We read them and store them to adapt the messages accordingly.
899 * Default is bad/good.
900 */
901void read_bisect_terms(const char **read_bad, const char **read_good)
902{
903 struct strbuf str = STRBUF_INIT;
904 const char *filename = git_path("BISECT_TERMS");
905 FILE *fp = fopen(filename, "r");
906
907 if (!fp) {
908 if (errno == ENOENT) {
909 *read_bad = "bad";
910 *read_good = "good";
911 return;
912 } else {
913 die("could not read file '%s': %s", filename,
914 strerror(errno));
915 }
916 } else {
8f309aeb 917 strbuf_getline_lf(&str, fp);
cb46d630 918 *read_bad = strbuf_detach(&str, NULL);
8f309aeb 919 strbuf_getline_lf(&str, fp);
cb46d630
AD
920 *read_good = strbuf_detach(&str, NULL);
921 }
922 strbuf_release(&str);
923 fclose(fp);
924}
925
ef24c7ca
CC
926/*
927 * We use the convention that exiting with an exit code 10 means that
928 * the bisection process finished successfully.
929 * In this case the calling shell script should exit 0.
fee92fc1
JS
930 *
931 * If no_checkout is non-zero, the bisection process does not
932 * checkout the trial commit but instead simply updates BISECT_HEAD.
ef24c7ca 933 */
fee92fc1 934int bisect_next_all(const char *prefix, int no_checkout)
ef24c7ca
CC
935{
936 struct rev_info revs;
937 struct commit_list *tried;
6329bade 938 int reaches = 0, all = 0, nr, steps;
ef24c7ca 939 const unsigned char *bisect_rev;
ef24c7ca 940
cb46d630 941 read_bisect_terms(&term_bad, &term_good);
2b020695
CC
942 if (read_bisect_refs())
943 die("reading bisect refs failed");
944
fee92fc1 945 check_good_are_ancestors_of_bad(prefix, no_checkout);
0871984d 946
a22347c6
CC
947 bisect_rev_setup(&revs, prefix, "%s", "^%s", 1);
948 revs.limited = 1;
2b020695 949
a22347c6 950 bisect_common(&revs);
ef24c7ca 951
a22347c6 952 revs.commits = find_bisection(revs.commits, &reaches, &all,
902bb364 953 !!skipped_revs.nr);
62d0b0da 954 revs.commits = managed_skipped(revs.commits, &tried);
ef24c7ca
CC
955
956 if (!revs.commits) {
957 /*
958 * We should exit here only if the "bad"
959 * commit is also a "skip" commit.
960 */
961 exit_if_skipped_commits(tried, NULL);
962
43f9d9f3
AD
963 printf("%s was both %s and %s\n",
964 oid_to_hex(current_bad_oid),
965 term_good,
966 term_bad);
ef24c7ca
CC
967 exit(1);
968 }
969
8f69f72f
CC
970 if (!all) {
971 fprintf(stderr, "No testable commit found.\n"
972 "Maybe you started with bad path parameters?\n");
973 exit(4);
974 }
975
ed1c9977 976 bisect_rev = revs.commits->item->object.oid.hash;
ef24c7ca 977
3c5ff995 978 if (!hashcmp(bisect_rev, current_bad_oid->hash)) {
979 exit_if_skipped_commits(tried, current_bad_oid);
080cc646 980 printf("%s is the first %s commit\n", sha1_to_hex(bisect_rev),
43f9d9f3 981 term_bad);
e22278c0 982 show_diff_tree(prefix, revs.commits->item);
ef24c7ca
CC
983 /* This means the bisection process succeeded. */
984 exit(10);
985 }
986
987 nr = all - reaches - 1;
6329bade
DR
988 steps = estimate_bisect_steps(all);
989 printf("Bisecting: %d revision%s left to test after this "
990 "(roughly %d step%s)\n", nr, (nr == 1 ? "" : "s"),
991 steps, (steps == 1 ? "" : "s"));
ef24c7ca 992
f3a97718 993 return bisect_checkout(bisect_rev, no_checkout);
ef24c7ca
CC
994}
995
c43cb386
NTND
996static inline int log2i(int n)
997{
998 int log2 = 0;
999
1000 for (; n > 1; n >>= 1)
1001 log2++;
1002
1003 return log2;
1004}
1005
1006static inline int exp2i(int n)
1007{
1008 return 1 << n;
1009}
1010
1011/*
1012 * Estimate the number of bisect steps left (after the current step)
1013 *
1014 * For any x between 0 included and 2^n excluded, the probability for
1015 * n - 1 steps left looks like:
1016 *
1017 * P(2^n + x) == (2^n - x) / (2^n + x)
1018 *
1019 * and P(2^n + x) < 0.5 means 2^n < 3x
1020 */
1021int estimate_bisect_steps(int all)
1022{
1023 int n, x, e;
1024
1025 if (all < 3)
1026 return 0;
1027
1028 n = log2i(all);
1029 e = exp2i(n);
1030 x = all - e;
1031
1032 return (e < 3 * x) ? n : n - 1;
1033}