Teach git-describe to use peeled ref information when scanning tags
[git] / builtin-rev-list.c
1 #include "cache.h"
2 #include "refs.h"
3 #include "tag.h"
4 #include "commit.h"
5 #include "tree.h"
6 #include "blob.h"
7 #include "tree-walk.h"
8 #include "diff.h"
9 #include "revision.h"
10 #include "list-objects.h"
11 #include "builtin.h"
12 #include "log-tree.h"
13
14 /* bits #0-15 in revision.h */
15
16 #define COUNTED         (1u<<16)
17
18 static const char rev_list_usage[] =
19 "git-rev-list [OPTION] <commit-id>... [ -- paths... ]\n"
20 "  limiting output:\n"
21 "    --max-count=nr\n"
22 "    --max-age=epoch\n"
23 "    --min-age=epoch\n"
24 "    --sparse\n"
25 "    --no-merges\n"
26 "    --remove-empty\n"
27 "    --all\n"
28 "    --stdin\n"
29 "    --quiet\n"
30 "  ordering output:\n"
31 "    --topo-order\n"
32 "    --date-order\n"
33 "  formatting output:\n"
34 "    --parents\n"
35 "    --objects | --objects-edge\n"
36 "    --unpacked\n"
37 "    --header | --pretty\n"
38 "    --abbrev=nr | --no-abbrev\n"
39 "    --abbrev-commit\n"
40 "    --left-right\n"
41 "  special purpose:\n"
42 "    --bisect\n"
43 "    --bisect-vars\n"
44 "    --bisect-all"
45 ;
46
47 static struct rev_info revs;
48
49 static int bisect_list;
50 static int show_timestamp;
51 static int hdr_termination;
52 static const char *header_prefix;
53
54 static void finish_commit(struct commit *commit);
55 static void show_commit(struct commit *commit)
56 {
57         if (show_timestamp)
58                 printf("%lu ", commit->date);
59         if (header_prefix)
60                 fputs(header_prefix, stdout);
61         if (commit->object.flags & BOUNDARY)
62                 putchar('-');
63         else if (commit->object.flags & UNINTERESTING)
64                 putchar('^');
65         else if (revs.left_right) {
66                 if (commit->object.flags & SYMMETRIC_LEFT)
67                         putchar('<');
68                 else
69                         putchar('>');
70         }
71         if (revs.abbrev_commit && revs.abbrev)
72                 fputs(find_unique_abbrev(commit->object.sha1, revs.abbrev),
73                       stdout);
74         else
75                 fputs(sha1_to_hex(commit->object.sha1), stdout);
76         if (revs.parents) {
77                 struct commit_list *parents = commit->parents;
78                 while (parents) {
79                         printf(" %s", sha1_to_hex(parents->item->object.sha1));
80                         parents = parents->next;
81                 }
82         }
83         show_decorations(commit);
84         if (revs.commit_format == CMIT_FMT_ONELINE)
85                 putchar(' ');
86         else
87                 putchar('\n');
88
89         if (revs.verbose_header && commit->buffer) {
90                 struct strbuf buf;
91                 strbuf_init(&buf, 0);
92                 pretty_print_commit(revs.commit_format, commit,
93                                     &buf, revs.abbrev, NULL, NULL,
94                                     revs.date_mode, 0);
95                 if (buf.len)
96                         printf("%s%c", buf.buf, hdr_termination);
97                 strbuf_release(&buf);
98         }
99         maybe_flush_or_die(stdout, "stdout");
100         finish_commit(commit);
101 }
102
103 static void finish_commit(struct commit *commit)
104 {
105         if (commit->parents) {
106                 free_commit_list(commit->parents);
107                 commit->parents = NULL;
108         }
109         free(commit->buffer);
110         commit->buffer = NULL;
111 }
112
113 static void finish_object(struct object_array_entry *p)
114 {
115         if (p->item->type == OBJ_BLOB && !has_sha1_file(p->item->sha1))
116                 die("missing blob object '%s'", sha1_to_hex(p->item->sha1));
117 }
118
119 static void show_object(struct object_array_entry *p)
120 {
121         /* An object with name "foo\n0000000..." can be used to
122          * confuse downstream git-pack-objects very badly.
123          */
124         const char *ep = strchr(p->name, '\n');
125
126         finish_object(p);
127         if (ep) {
128                 printf("%s %.*s\n", sha1_to_hex(p->item->sha1),
129                        (int) (ep - p->name),
130                        p->name);
131         }
132         else
133                 printf("%s %s\n", sha1_to_hex(p->item->sha1), p->name);
134 }
135
136 static void show_edge(struct commit *commit)
137 {
138         printf("-%s\n", sha1_to_hex(commit->object.sha1));
139 }
140
141 /*
142  * This is a truly stupid algorithm, but it's only
143  * used for bisection, and we just don't care enough.
144  *
145  * We care just barely enough to avoid recursing for
146  * non-merge entries.
147  */
148 static int count_distance(struct commit_list *entry)
149 {
150         int nr = 0;
151
152         while (entry) {
153                 struct commit *commit = entry->item;
154                 struct commit_list *p;
155
156                 if (commit->object.flags & (UNINTERESTING | COUNTED))
157                         break;
158                 if (!(commit->object.flags & TREESAME))
159                         nr++;
160                 commit->object.flags |= COUNTED;
161                 p = commit->parents;
162                 entry = p;
163                 if (p) {
164                         p = p->next;
165                         while (p) {
166                                 nr += count_distance(p);
167                                 p = p->next;
168                         }
169                 }
170         }
171
172         return nr;
173 }
174
175 static void clear_distance(struct commit_list *list)
176 {
177         while (list) {
178                 struct commit *commit = list->item;
179                 commit->object.flags &= ~COUNTED;
180                 list = list->next;
181         }
182 }
183
184 #define DEBUG_BISECT 0
185
186 static inline int weight(struct commit_list *elem)
187 {
188         return *((int*)(elem->item->util));
189 }
190
191 static inline void weight_set(struct commit_list *elem, int weight)
192 {
193         *((int*)(elem->item->util)) = weight;
194 }
195
196 static int count_interesting_parents(struct commit *commit)
197 {
198         struct commit_list *p;
199         int count;
200
201         for (count = 0, p = commit->parents; p; p = p->next) {
202                 if (p->item->object.flags & UNINTERESTING)
203                         continue;
204                 count++;
205         }
206         return count;
207 }
208
209 static inline int halfway(struct commit_list *p, int nr)
210 {
211         /*
212          * Don't short-cut something we are not going to return!
213          */
214         if (p->item->object.flags & TREESAME)
215                 return 0;
216         if (DEBUG_BISECT)
217                 return 0;
218         /*
219          * 2 and 3 are halfway of 5.
220          * 3 is halfway of 6 but 2 and 4 are not.
221          */
222         switch (2 * weight(p) - nr) {
223         case -1: case 0: case 1:
224                 return 1;
225         default:
226                 return 0;
227         }
228 }
229
230 #if !DEBUG_BISECT
231 #define show_list(a,b,c,d) do { ; } while (0)
232 #else
233 static void show_list(const char *debug, int counted, int nr,
234                       struct commit_list *list)
235 {
236         struct commit_list *p;
237
238         fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr);
239
240         for (p = list; p; p = p->next) {
241                 struct commit_list *pp;
242                 struct commit *commit = p->item;
243                 unsigned flags = commit->object.flags;
244                 enum object_type type;
245                 unsigned long size;
246                 char *buf = read_sha1_file(commit->object.sha1, &type, &size);
247                 char *ep, *sp;
248
249                 fprintf(stderr, "%c%c%c ",
250                         (flags & TREESAME) ? ' ' : 'T',
251                         (flags & UNINTERESTING) ? 'U' : ' ',
252                         (flags & COUNTED) ? 'C' : ' ');
253                 if (commit->util)
254                         fprintf(stderr, "%3d", weight(p));
255                 else
256                         fprintf(stderr, "---");
257                 fprintf(stderr, " %.*s", 8, sha1_to_hex(commit->object.sha1));
258                 for (pp = commit->parents; pp; pp = pp->next)
259                         fprintf(stderr, " %.*s", 8,
260                                 sha1_to_hex(pp->item->object.sha1));
261
262                 sp = strstr(buf, "\n\n");
263                 if (sp) {
264                         sp += 2;
265                         for (ep = sp; *ep && *ep != '\n'; ep++)
266                                 ;
267                         fprintf(stderr, " %.*s", (int)(ep - sp), sp);
268                 }
269                 fprintf(stderr, "\n");
270         }
271 }
272 #endif /* DEBUG_BISECT */
273
274 static struct commit_list *best_bisection(struct commit_list *list, int nr)
275 {
276         struct commit_list *p, *best;
277         int best_distance = -1;
278
279         best = list;
280         for (p = list; p; p = p->next) {
281                 int distance;
282                 unsigned flags = p->item->object.flags;
283
284                 if (flags & TREESAME)
285                         continue;
286                 distance = weight(p);
287                 if (nr - distance < distance)
288                         distance = nr - distance;
289                 if (distance > best_distance) {
290                         best = p;
291                         best_distance = distance;
292                 }
293         }
294
295         return best;
296 }
297
298 struct commit_dist {
299         struct commit *commit;
300         int distance;
301 };
302
303 static int compare_commit_dist(const void *a_, const void *b_)
304 {
305         struct commit_dist *a, *b;
306
307         a = (struct commit_dist *)a_;
308         b = (struct commit_dist *)b_;
309         if (a->distance != b->distance)
310                 return b->distance - a->distance; /* desc sort */
311         return hashcmp(a->commit->object.sha1, b->commit->object.sha1);
312 }
313
314 static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
315 {
316         struct commit_list *p;
317         struct commit_dist *array = xcalloc(nr, sizeof(*array));
318         int cnt, i;
319
320         for (p = list, cnt = 0; p; p = p->next) {
321                 int distance;
322                 unsigned flags = p->item->object.flags;
323
324                 if (flags & TREESAME)
325                         continue;
326                 distance = weight(p);
327                 if (nr - distance < distance)
328                         distance = nr - distance;
329                 array[cnt].commit = p->item;
330                 array[cnt].distance = distance;
331                 cnt++;
332         }
333         qsort(array, cnt, sizeof(*array), compare_commit_dist);
334         for (p = list, i = 0; i < cnt; i++) {
335                 struct name_decoration *r = xmalloc(sizeof(*r) + 100);
336                 struct object *obj = &(array[i].commit->object);
337
338                 sprintf(r->name, "dist=%d", array[i].distance);
339                 r->next = add_decoration(&name_decoration, obj, r);
340                 p->item = array[i].commit;
341                 p = p->next;
342         }
343         if (p)
344                 p->next = NULL;
345         free(array);
346         return list;
347 }
348
349 /*
350  * zero or positive weight is the number of interesting commits it can
351  * reach, including itself.  Especially, weight = 0 means it does not
352  * reach any tree-changing commits (e.g. just above uninteresting one
353  * but traversal is with pathspec).
354  *
355  * weight = -1 means it has one parent and its distance is yet to
356  * be computed.
357  *
358  * weight = -2 means it has more than one parent and its distance is
359  * unknown.  After running count_distance() first, they will get zero
360  * or positive distance.
361  */
362 static struct commit_list *do_find_bisection(struct commit_list *list,
363                                              int nr, int *weights,
364                                              int find_all)
365 {
366         int n, counted;
367         struct commit_list *p;
368
369         counted = 0;
370
371         for (n = 0, p = list; p; p = p->next) {
372                 struct commit *commit = p->item;
373                 unsigned flags = commit->object.flags;
374
375                 p->item->util = &weights[n++];
376                 switch (count_interesting_parents(commit)) {
377                 case 0:
378                         if (!(flags & TREESAME)) {
379                                 weight_set(p, 1);
380                                 counted++;
381                                 show_list("bisection 2 count one",
382                                           counted, nr, list);
383                         }
384                         /*
385                          * otherwise, it is known not to reach any
386                          * tree-changing commit and gets weight 0.
387                          */
388                         break;
389                 case 1:
390                         weight_set(p, -1);
391                         break;
392                 default:
393                         weight_set(p, -2);
394                         break;
395                 }
396         }
397
398         show_list("bisection 2 initialize", counted, nr, list);
399
400         /*
401          * If you have only one parent in the resulting set
402          * then you can reach one commit more than that parent
403          * can reach.  So we do not have to run the expensive
404          * count_distance() for single strand of pearls.
405          *
406          * However, if you have more than one parents, you cannot
407          * just add their distance and one for yourself, since
408          * they usually reach the same ancestor and you would
409          * end up counting them twice that way.
410          *
411          * So we will first count distance of merges the usual
412          * way, and then fill the blanks using cheaper algorithm.
413          */
414         for (p = list; p; p = p->next) {
415                 if (p->item->object.flags & UNINTERESTING)
416                         continue;
417                 if (weight(p) != -2)
418                         continue;
419                 weight_set(p, count_distance(p));
420                 clear_distance(list);
421
422                 /* Does it happen to be at exactly half-way? */
423                 if (!find_all && halfway(p, nr))
424                         return p;
425                 counted++;
426         }
427
428         show_list("bisection 2 count_distance", counted, nr, list);
429
430         while (counted < nr) {
431                 for (p = list; p; p = p->next) {
432                         struct commit_list *q;
433                         unsigned flags = p->item->object.flags;
434
435                         if (0 <= weight(p))
436                                 continue;
437                         for (q = p->item->parents; q; q = q->next) {
438                                 if (q->item->object.flags & UNINTERESTING)
439                                         continue;
440                                 if (0 <= weight(q))
441                                         break;
442                         }
443                         if (!q)
444                                 continue;
445
446                         /*
447                          * weight for p is unknown but q is known.
448                          * add one for p itself if p is to be counted,
449                          * otherwise inherit it from q directly.
450                          */
451                         if (!(flags & TREESAME)) {
452                                 weight_set(p, weight(q)+1);
453                                 counted++;
454                                 show_list("bisection 2 count one",
455                                           counted, nr, list);
456                         }
457                         else
458                                 weight_set(p, weight(q));
459
460                         /* Does it happen to be at exactly half-way? */
461                         if (!find_all && halfway(p, nr))
462                                 return p;
463                 }
464         }
465
466         show_list("bisection 2 counted all", counted, nr, list);
467
468         if (!find_all)
469                 return best_bisection(list, nr);
470         else
471                 return best_bisection_sorted(list, nr);
472 }
473
474 static struct commit_list *find_bisection(struct commit_list *list,
475                                           int *reaches, int *all,
476                                           int find_all)
477 {
478         int nr, on_list;
479         struct commit_list *p, *best, *next, *last;
480         int *weights;
481
482         show_list("bisection 2 entry", 0, 0, list);
483
484         /*
485          * Count the number of total and tree-changing items on the
486          * list, while reversing the list.
487          */
488         for (nr = on_list = 0, last = NULL, p = list;
489              p;
490              p = next) {
491                 unsigned flags = p->item->object.flags;
492
493                 next = p->next;
494                 if (flags & UNINTERESTING)
495                         continue;
496                 p->next = last;
497                 last = p;
498                 if (!(flags & TREESAME))
499                         nr++;
500                 on_list++;
501         }
502         list = last;
503         show_list("bisection 2 sorted", 0, nr, list);
504
505         *all = nr;
506         weights = xcalloc(on_list, sizeof(*weights));
507
508         /* Do the real work of finding bisection commit. */
509         best = do_find_bisection(list, nr, weights, find_all);
510         if (best) {
511                 if (!find_all)
512                         best->next = NULL;
513                 *reaches = weight(best);
514         }
515         free(weights);
516         return best;
517 }
518
519 static void read_revisions_from_stdin(struct rev_info *revs)
520 {
521         char line[1000];
522
523         while (fgets(line, sizeof(line), stdin) != NULL) {
524                 int len = strlen(line);
525                 if (len && line[len - 1] == '\n')
526                         line[--len] = 0;
527                 if (!len)
528                         break;
529                 if (line[0] == '-')
530                         die("options not supported in --stdin mode");
531                 if (handle_revision_arg(line, revs, 0, 1))
532                         die("bad revision '%s'", line);
533         }
534 }
535
536 int cmd_rev_list(int argc, const char **argv, const char *prefix)
537 {
538         struct commit_list *list;
539         int i;
540         int read_from_stdin = 0;
541         int bisect_show_vars = 0;
542         int bisect_find_all = 0;
543         int quiet = 0;
544
545         git_config(git_default_config);
546         init_revisions(&revs, prefix);
547         revs.abbrev = 0;
548         revs.commit_format = CMIT_FMT_UNSPECIFIED;
549         argc = setup_revisions(argc, argv, &revs, NULL);
550
551         for (i = 1 ; i < argc; i++) {
552                 const char *arg = argv[i];
553
554                 if (!strcmp(arg, "--header")) {
555                         revs.verbose_header = 1;
556                         continue;
557                 }
558                 if (!strcmp(arg, "--timestamp")) {
559                         show_timestamp = 1;
560                         continue;
561                 }
562                 if (!strcmp(arg, "--bisect")) {
563                         bisect_list = 1;
564                         continue;
565                 }
566                 if (!strcmp(arg, "--bisect-all")) {
567                         bisect_list = 1;
568                         bisect_find_all = 1;
569                         continue;
570                 }
571                 if (!strcmp(arg, "--bisect-vars")) {
572                         bisect_list = 1;
573                         bisect_show_vars = 1;
574                         continue;
575                 }
576                 if (!strcmp(arg, "--stdin")) {
577                         if (read_from_stdin++)
578                                 die("--stdin given twice?");
579                         read_revisions_from_stdin(&revs);
580                         continue;
581                 }
582                 if (!strcmp(arg, "--quiet")) {
583                         quiet = 1;
584                         continue;
585                 }
586                 usage(rev_list_usage);
587
588         }
589         if (revs.commit_format != CMIT_FMT_UNSPECIFIED) {
590                 /* The command line has a --pretty  */
591                 hdr_termination = '\n';
592                 if (revs.commit_format == CMIT_FMT_ONELINE)
593                         header_prefix = "";
594                 else
595                         header_prefix = "commit ";
596         }
597         else if (revs.verbose_header)
598                 /* Only --header was specified */
599                 revs.commit_format = CMIT_FMT_RAW;
600
601         list = revs.commits;
602
603         if ((!list &&
604              (!(revs.tag_objects||revs.tree_objects||revs.blob_objects) &&
605               !revs.pending.nr)) ||
606             revs.diff)
607                 usage(rev_list_usage);
608
609         save_commit_buffer = revs.verbose_header || revs.grep_filter;
610         track_object_refs = 0;
611         if (bisect_list)
612                 revs.limited = 1;
613
614         if (prepare_revision_walk(&revs))
615                 die("revision walk setup failed");
616         if (revs.tree_objects)
617                 mark_edges_uninteresting(revs.commits, &revs, show_edge);
618
619         if (bisect_list) {
620                 int reaches = reaches, all = all;
621
622                 revs.commits = find_bisection(revs.commits, &reaches, &all,
623                                               bisect_find_all);
624                 if (bisect_show_vars) {
625                         int cnt;
626                         char hex[41];
627                         if (!revs.commits)
628                                 return 1;
629                         /*
630                          * revs.commits can reach "reaches" commits among
631                          * "all" commits.  If it is good, then there are
632                          * (all-reaches) commits left to be bisected.
633                          * On the other hand, if it is bad, then the set
634                          * to bisect is "reaches".
635                          * A bisect set of size N has (N-1) commits further
636                          * to test, as we already know one bad one.
637                          */
638                         cnt = all - reaches;
639                         if (cnt < reaches)
640                                 cnt = reaches;
641                         strcpy(hex, sha1_to_hex(revs.commits->item->object.sha1));
642
643                         if (bisect_find_all) {
644                                 traverse_commit_list(&revs, show_commit, show_object);
645                                 printf("------\n");
646                         }
647
648                         printf("bisect_rev=%s\n"
649                                "bisect_nr=%d\n"
650                                "bisect_good=%d\n"
651                                "bisect_bad=%d\n"
652                                "bisect_all=%d\n",
653                                hex,
654                                cnt - 1,
655                                all - reaches - 1,
656                                reaches - 1,
657                                all);
658                         return 0;
659                 }
660         }
661
662         traverse_commit_list(&revs,
663                 quiet ? finish_commit : show_commit,
664                 quiet ? finish_object : show_object);
665
666         return 0;
667 }