User Manual: add a chapter for submodules
[git] / diff-lib.c
1 /*
2  * Copyright (C) 2005 Junio C Hamano
3  */
4 #include "cache.h"
5 #include "quote.h"
6 #include "commit.h"
7 #include "diff.h"
8 #include "diffcore.h"
9 #include "revision.h"
10 #include "cache-tree.h"
11 #include "path-list.h"
12
13 /*
14  * diff-files
15  */
16
17 static int read_directory(const char *path, struct path_list *list)
18 {
19         DIR *dir;
20         struct dirent *e;
21
22         if (!(dir = opendir(path)))
23                 return error("Could not open directory %s", path);
24
25         while ((e = readdir(dir)))
26                 if (strcmp(".", e->d_name) && strcmp("..", e->d_name))
27                         path_list_insert(e->d_name, list);
28
29         closedir(dir);
30         return 0;
31 }
32
33 static int get_mode(const char *path, int *mode)
34 {
35         struct stat st;
36
37         if (!path || !strcmp(path, "/dev/null"))
38                 *mode = 0;
39         else if (!strcmp(path, "-"))
40                 *mode = ntohl(create_ce_mode(0666));
41         else if (stat(path, &st))
42                 return error("Could not access '%s'", path);
43         else
44                 *mode = st.st_mode;
45         return 0;
46 }
47
48 static int queue_diff(struct diff_options *o,
49                 const char *name1, const char *name2)
50 {
51         int mode1 = 0, mode2 = 0;
52
53         if (get_mode(name1, &mode1) || get_mode(name2, &mode2))
54                 return -1;
55
56         if (mode1 && mode2 && S_ISDIR(mode1) != S_ISDIR(mode2))
57                 return error("file/directory conflict: %s, %s", name1, name2);
58
59         if (S_ISDIR(mode1) || S_ISDIR(mode2)) {
60                 char buffer1[PATH_MAX], buffer2[PATH_MAX];
61                 struct path_list p1 = {NULL, 0, 0, 1}, p2 = {NULL, 0, 0, 1};
62                 int len1 = 0, len2 = 0, i1, i2, ret = 0;
63
64                 if (name1 && read_directory(name1, &p1))
65                         return -1;
66                 if (name2 && read_directory(name2, &p2)) {
67                         path_list_clear(&p1, 0);
68                         return -1;
69                 }
70
71                 if (name1) {
72                         len1 = strlen(name1);
73                         if (len1 > 0 && name1[len1 - 1] == '/')
74                                 len1--;
75                         memcpy(buffer1, name1, len1);
76                         buffer1[len1++] = '/';
77                 }
78
79                 if (name2) {
80                         len2 = strlen(name2);
81                         if (len2 > 0 && name2[len2 - 1] == '/')
82                                 len2--;
83                         memcpy(buffer2, name2, len2);
84                         buffer2[len2++] = '/';
85                 }
86
87                 for (i1 = i2 = 0; !ret && (i1 < p1.nr || i2 < p2.nr); ) {
88                         const char *n1, *n2;
89                         int comp;
90
91                         if (i1 == p1.nr)
92                                 comp = 1;
93                         else if (i2 == p2.nr)
94                                 comp = -1;
95                         else
96                                 comp = strcmp(p1.items[i1].path,
97                                         p2.items[i2].path);
98
99                         if (comp > 0)
100                                 n1 = NULL;
101                         else {
102                                 n1 = buffer1;
103                                 strncpy(buffer1 + len1, p1.items[i1++].path,
104                                                 PATH_MAX - len1);
105                         }
106
107                         if (comp < 0)
108                                 n2 = NULL;
109                         else {
110                                 n2 = buffer2;
111                                 strncpy(buffer2 + len2, p2.items[i2++].path,
112                                                 PATH_MAX - len2);
113                         }
114
115                         ret = queue_diff(o, n1, n2);
116                 }
117                 path_list_clear(&p1, 0);
118                 path_list_clear(&p2, 0);
119
120                 return ret;
121         } else {
122                 struct diff_filespec *d1, *d2;
123
124                 if (o->reverse_diff) {
125                         unsigned tmp;
126                         const char *tmp_c;
127                         tmp = mode1; mode1 = mode2; mode2 = tmp;
128                         tmp_c = name1; name1 = name2; name2 = tmp_c;
129                 }
130
131                 if (!name1)
132                         name1 = "/dev/null";
133                 if (!name2)
134                         name2 = "/dev/null";
135                 d1 = alloc_filespec(name1);
136                 d2 = alloc_filespec(name2);
137                 fill_filespec(d1, null_sha1, mode1);
138                 fill_filespec(d2, null_sha1, mode2);
139
140                 diff_queue(&diff_queued_diff, d1, d2);
141                 return 0;
142         }
143 }
144
145 /*
146  * Does the path name a blob in the working tree, or a directory
147  * in the working tree?
148  */
149 static int is_in_index(const char *path)
150 {
151         int len, pos;
152         struct cache_entry *ce;
153
154         len = strlen(path);
155         while (path[len-1] == '/')
156                 len--;
157         if (!len)
158                 return 1; /* "." */
159         pos = cache_name_pos(path, len);
160         if (0 <= pos)
161                 return 1;
162         pos = -1 - pos;
163         while (pos < active_nr) {
164                 ce = active_cache[pos++];
165                 if (ce_namelen(ce) <= len ||
166                     strncmp(ce->name, path, len) ||
167                     (ce->name[len] > '/'))
168                         break; /* path cannot be a prefix */
169                 if (ce->name[len] == '/')
170                         return 1;
171         }
172         return 0;
173 }
174
175 static int handle_diff_files_args(struct rev_info *revs,
176                 int argc, const char **argv, int *silent)
177 {
178         *silent = 0;
179
180         /* revs->max_count == -2 means --no-index */
181         while (1 < argc && argv[1][0] == '-') {
182                 if (!strcmp(argv[1], "--base"))
183                         revs->max_count = 1;
184                 else if (!strcmp(argv[1], "--ours"))
185                         revs->max_count = 2;
186                 else if (!strcmp(argv[1], "--theirs"))
187                         revs->max_count = 3;
188                 else if (!strcmp(argv[1], "-n") ||
189                                 !strcmp(argv[1], "--no-index")) {
190                         revs->max_count = -2;
191                         revs->diffopt.exit_with_status = 1;
192                         revs->diffopt.no_index = 1;
193                 }
194                 else if (!strcmp(argv[1], "-q"))
195                         *silent = 1;
196                 else
197                         return error("invalid option: %s", argv[1]);
198                 argv++; argc--;
199         }
200
201         if (revs->max_count == -1 && revs->diffopt.nr_paths == 2) {
202                 /*
203                  * If two files are specified, and at least one is untracked,
204                  * default to no-index.
205                  */
206                 read_cache();
207                 if (!is_in_index(revs->diffopt.paths[0]) ||
208                                         !is_in_index(revs->diffopt.paths[1])) {
209                         revs->max_count = -2;
210                         revs->diffopt.no_index = 1;
211                 }
212         }
213
214         /*
215          * Make sure there are NO revision (i.e. pending object) parameter,
216          * rev.max_count is reasonable (0 <= n <= 3),
217          * there is no other revision filtering parameters.
218          */
219         if (revs->pending.nr || revs->max_count > 3 ||
220             revs->min_age != -1 || revs->max_age != -1)
221                 return error("no revision allowed with diff-files");
222
223         if (revs->max_count == -1 &&
224             (revs->diffopt.output_format & DIFF_FORMAT_PATCH))
225                 revs->combine_merges = revs->dense_combined_merges = 1;
226
227         return 0;
228 }
229
230 static int is_outside_repo(const char *path, int nongit, const char *prefix)
231 {
232         int i;
233         if (nongit || !strcmp(path, "-") || path[0] == '/')
234                 return 1;
235         if (prefixcmp(path, "../"))
236                 return 0;
237         if (!prefix)
238                 return 1;
239         for (i = strlen(prefix); !prefixcmp(path, "../"); ) {
240                 while (i > 0 && prefix[i - 1] != '/')
241                         i--;
242                 if (--i < 0)
243                         return 1;
244                 path += 3;
245         }
246         return 0;
247 }
248
249 int setup_diff_no_index(struct rev_info *revs,
250                 int argc, const char ** argv, int nongit, const char *prefix)
251 {
252         int i;
253         for (i = 1; i < argc; i++)
254                 if (argv[i][0] != '-' || argv[i][1] == '\0')
255                         break;
256                 else if (!strcmp(argv[i], "--")) {
257                         i++;
258                         break;
259                 } else if (i < argc - 3 && !strcmp(argv[i], "--no-index")) {
260                         i = argc - 3;
261                         revs->diffopt.exit_with_status = 1;
262                         break;
263                 }
264         if (argc != i + 2 || (!is_outside_repo(argv[i + 1], nongit, prefix) &&
265                                 !is_outside_repo(argv[i], nongit, prefix)))
266                 return -1;
267
268         diff_setup(&revs->diffopt);
269         for (i = 1; i < argc - 2; )
270                 if (!strcmp(argv[i], "--no-index"))
271                         i++;
272                 else {
273                         int j = diff_opt_parse(&revs->diffopt,
274                                         argv + i, argc - i);
275                         if (!j)
276                                 die("invalid diff option/value: %s", argv[i]);
277                         i += j;
278                 }
279
280         if (prefix) {
281                 int len = strlen(prefix);
282
283                 revs->diffopt.paths = xcalloc(2, sizeof(char*));
284                 for (i = 0; i < 2; i++) {
285                         const char *p = argv[argc - 2 + i];
286                         /*
287                          * stdin should be spelled as '-'; if you have
288                          * path that is '-', spell it as ./-.
289                          */
290                         p = (strcmp(p, "-")
291                              ? xstrdup(prefix_filename(prefix, len, p))
292                              : p);
293                         revs->diffopt.paths[i] = p;
294                 }
295         }
296         else
297                 revs->diffopt.paths = argv + argc - 2;
298         revs->diffopt.nr_paths = 2;
299         revs->diffopt.no_index = 1;
300         revs->max_count = -2;
301         if (diff_setup_done(&revs->diffopt) < 0)
302                 die("diff_setup_done failed");
303         return 0;
304 }
305
306 int run_diff_files_cmd(struct rev_info *revs, int argc, const char **argv)
307 {
308         int silent_on_removed;
309
310         if (handle_diff_files_args(revs, argc, argv, &silent_on_removed))
311                 return -1;
312
313         if (revs->diffopt.no_index) {
314                 if (revs->diffopt.nr_paths != 2)
315                         return error("need two files/directories with --no-index");
316                 if (queue_diff(&revs->diffopt, revs->diffopt.paths[0],
317                                 revs->diffopt.paths[1]))
318                         return -1;
319                 diffcore_std(&revs->diffopt);
320                 diff_flush(&revs->diffopt);
321                 /*
322                  * The return code for --no-index imitates diff(1):
323                  * 0 = no changes, 1 = changes, else error
324                  */
325                 return revs->diffopt.found_changes;
326         }
327
328         if (read_cache() < 0) {
329                 perror("read_cache");
330                 return -1;
331         }
332         return run_diff_files(revs, silent_on_removed);
333 }
334
335 int run_diff_files(struct rev_info *revs, int silent_on_removed)
336 {
337         int entries, i;
338         int diff_unmerged_stage = revs->max_count;
339
340         if (diff_unmerged_stage < 0)
341                 diff_unmerged_stage = 2;
342         entries = active_nr;
343         for (i = 0; i < entries; i++) {
344                 struct stat st;
345                 unsigned int oldmode, newmode;
346                 struct cache_entry *ce = active_cache[i];
347                 int changed;
348
349                 if (revs->diffopt.quiet && revs->diffopt.has_changes)
350                         break;
351
352                 if (!ce_path_match(ce, revs->prune_data))
353                         continue;
354
355                 if (ce_stage(ce)) {
356                         struct combine_diff_path *dpath;
357                         int num_compare_stages = 0;
358                         size_t path_len;
359
360                         path_len = ce_namelen(ce);
361
362                         dpath = xmalloc(combine_diff_path_size(5, path_len));
363                         dpath->path = (char *) &(dpath->parent[5]);
364
365                         dpath->next = NULL;
366                         dpath->len = path_len;
367                         memcpy(dpath->path, ce->name, path_len);
368                         dpath->path[path_len] = '\0';
369                         hashclr(dpath->sha1);
370                         memset(&(dpath->parent[0]), 0,
371                                sizeof(struct combine_diff_parent)*5);
372
373                         if (lstat(ce->name, &st) < 0) {
374                                 if (errno != ENOENT && errno != ENOTDIR) {
375                                         perror(ce->name);
376                                         continue;
377                                 }
378                                 if (silent_on_removed)
379                                         continue;
380                         }
381                         else
382                                 dpath->mode = ntohl(ce_mode_from_stat(ce, st.st_mode));
383
384                         while (i < entries) {
385                                 struct cache_entry *nce = active_cache[i];
386                                 int stage;
387
388                                 if (strcmp(ce->name, nce->name))
389                                         break;
390
391                                 /* Stage #2 (ours) is the first parent,
392                                  * stage #3 (theirs) is the second.
393                                  */
394                                 stage = ce_stage(nce);
395                                 if (2 <= stage) {
396                                         int mode = ntohl(nce->ce_mode);
397                                         num_compare_stages++;
398                                         hashcpy(dpath->parent[stage-2].sha1, nce->sha1);
399                                         dpath->parent[stage-2].mode = ntohl(ce_mode_from_stat(nce, mode));
400                                         dpath->parent[stage-2].status =
401                                                 DIFF_STATUS_MODIFIED;
402                                 }
403
404                                 /* diff against the proper unmerged stage */
405                                 if (stage == diff_unmerged_stage)
406                                         ce = nce;
407                                 i++;
408                         }
409                         /*
410                          * Compensate for loop update
411                          */
412                         i--;
413
414                         if (revs->combine_merges && num_compare_stages == 2) {
415                                 show_combined_diff(dpath, 2,
416                                                    revs->dense_combined_merges,
417                                                    revs);
418                                 free(dpath);
419                                 continue;
420                         }
421                         free(dpath);
422                         dpath = NULL;
423
424                         /*
425                          * Show the diff for the 'ce' if we found the one
426                          * from the desired stage.
427                          */
428                         diff_unmerge(&revs->diffopt, ce->name, 0, null_sha1);
429                         if (ce_stage(ce) != diff_unmerged_stage)
430                                 continue;
431                 }
432
433                 if (lstat(ce->name, &st) < 0) {
434                         if (errno != ENOENT && errno != ENOTDIR) {
435                                 perror(ce->name);
436                                 continue;
437                         }
438                         if (silent_on_removed)
439                                 continue;
440                         diff_addremove(&revs->diffopt, '-', ntohl(ce->ce_mode),
441                                        ce->sha1, ce->name, NULL);
442                         continue;
443                 }
444                 changed = ce_match_stat(ce, &st, 0);
445                 if (!changed && !revs->diffopt.find_copies_harder)
446                         continue;
447                 oldmode = ntohl(ce->ce_mode);
448                 newmode = ntohl(ce_mode_from_stat(ce, st.st_mode));
449                 diff_change(&revs->diffopt, oldmode, newmode,
450                             ce->sha1, (changed ? null_sha1 : ce->sha1),
451                             ce->name, NULL);
452
453         }
454         diffcore_std(&revs->diffopt);
455         diff_flush(&revs->diffopt);
456         return 0;
457 }
458
459 /*
460  * diff-index
461  */
462
463 /* A file entry went away or appeared */
464 static void diff_index_show_file(struct rev_info *revs,
465                                  const char *prefix,
466                                  struct cache_entry *ce,
467                                  unsigned char *sha1, unsigned int mode)
468 {
469         diff_addremove(&revs->diffopt, prefix[0], ntohl(mode),
470                        sha1, ce->name, NULL);
471 }
472
473 static int get_stat_data(struct cache_entry *ce,
474                          unsigned char **sha1p,
475                          unsigned int *modep,
476                          int cached, int match_missing)
477 {
478         unsigned char *sha1 = ce->sha1;
479         unsigned int mode = ce->ce_mode;
480
481         if (!cached) {
482                 static unsigned char no_sha1[20];
483                 int changed;
484                 struct stat st;
485                 if (lstat(ce->name, &st) < 0) {
486                         if (errno == ENOENT && match_missing) {
487                                 *sha1p = sha1;
488                                 *modep = mode;
489                                 return 0;
490                         }
491                         return -1;
492                 }
493                 changed = ce_match_stat(ce, &st, 0);
494                 if (changed) {
495                         mode = ce_mode_from_stat(ce, st.st_mode);
496                         sha1 = no_sha1;
497                 }
498         }
499
500         *sha1p = sha1;
501         *modep = mode;
502         return 0;
503 }
504
505 static void show_new_file(struct rev_info *revs,
506                           struct cache_entry *new,
507                           int cached, int match_missing)
508 {
509         unsigned char *sha1;
510         unsigned int mode;
511
512         /* New file in the index: it might actually be different in
513          * the working copy.
514          */
515         if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0)
516                 return;
517
518         diff_index_show_file(revs, "+", new, sha1, mode);
519 }
520
521 static int show_modified(struct rev_info *revs,
522                          struct cache_entry *old,
523                          struct cache_entry *new,
524                          int report_missing,
525                          int cached, int match_missing)
526 {
527         unsigned int mode, oldmode;
528         unsigned char *sha1;
529
530         if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0) {
531                 if (report_missing)
532                         diff_index_show_file(revs, "-", old,
533                                              old->sha1, old->ce_mode);
534                 return -1;
535         }
536
537         if (revs->combine_merges && !cached &&
538             (hashcmp(sha1, old->sha1) || hashcmp(old->sha1, new->sha1))) {
539                 struct combine_diff_path *p;
540                 int pathlen = ce_namelen(new);
541
542                 p = xmalloc(combine_diff_path_size(2, pathlen));
543                 p->path = (char *) &p->parent[2];
544                 p->next = NULL;
545                 p->len = pathlen;
546                 memcpy(p->path, new->name, pathlen);
547                 p->path[pathlen] = 0;
548                 p->mode = ntohl(mode);
549                 hashclr(p->sha1);
550                 memset(p->parent, 0, 2 * sizeof(struct combine_diff_parent));
551                 p->parent[0].status = DIFF_STATUS_MODIFIED;
552                 p->parent[0].mode = ntohl(new->ce_mode);
553                 hashcpy(p->parent[0].sha1, new->sha1);
554                 p->parent[1].status = DIFF_STATUS_MODIFIED;
555                 p->parent[1].mode = ntohl(old->ce_mode);
556                 hashcpy(p->parent[1].sha1, old->sha1);
557                 show_combined_diff(p, 2, revs->dense_combined_merges, revs);
558                 free(p);
559                 return 0;
560         }
561
562         oldmode = old->ce_mode;
563         if (mode == oldmode && !hashcmp(sha1, old->sha1) &&
564             !revs->diffopt.find_copies_harder)
565                 return 0;
566
567         mode = ntohl(mode);
568         oldmode = ntohl(oldmode);
569
570         diff_change(&revs->diffopt, oldmode, mode,
571                     old->sha1, sha1, old->name, NULL);
572         return 0;
573 }
574
575 static int diff_cache(struct rev_info *revs,
576                       struct cache_entry **ac, int entries,
577                       const char **pathspec,
578                       int cached, int match_missing)
579 {
580         while (entries) {
581                 struct cache_entry *ce = *ac;
582                 int same = (entries > 1) && ce_same_name(ce, ac[1]);
583
584                 if (revs->diffopt.quiet && revs->diffopt.has_changes)
585                         break;
586
587                 if (!ce_path_match(ce, pathspec))
588                         goto skip_entry;
589
590                 switch (ce_stage(ce)) {
591                 case 0:
592                         /* No stage 1 entry? That means it's a new file */
593                         if (!same) {
594                                 show_new_file(revs, ce, cached, match_missing);
595                                 break;
596                         }
597                         /* Show difference between old and new */
598                         show_modified(revs, ac[1], ce, 1,
599                                       cached, match_missing);
600                         break;
601                 case 1:
602                         /* No stage 3 (merge) entry?
603                          * That means it's been deleted.
604                          */
605                         if (!same) {
606                                 diff_index_show_file(revs, "-", ce,
607                                                      ce->sha1, ce->ce_mode);
608                                 break;
609                         }
610                         /* We come here with ce pointing at stage 1
611                          * (original tree) and ac[1] pointing at stage
612                          * 3 (unmerged).  show-modified with
613                          * report-missing set to false does not say the
614                          * file is deleted but reports true if work
615                          * tree does not have it, in which case we
616                          * fall through to report the unmerged state.
617                          * Otherwise, we show the differences between
618                          * the original tree and the work tree.
619                          */
620                         if (!cached &&
621                             !show_modified(revs, ce, ac[1], 0,
622                                            cached, match_missing))
623                                 break;
624                         diff_unmerge(&revs->diffopt, ce->name,
625                                      ntohl(ce->ce_mode), ce->sha1);
626                         break;
627                 case 3:
628                         diff_unmerge(&revs->diffopt, ce->name,
629                                      0, null_sha1);
630                         break;
631
632                 default:
633                         die("impossible cache entry stage");
634                 }
635
636 skip_entry:
637                 /*
638                  * Ignore all the different stages for this file,
639                  * we've handled the relevant cases now.
640                  */
641                 do {
642                         ac++;
643                         entries--;
644                 } while (entries && ce_same_name(ce, ac[0]));
645         }
646         return 0;
647 }
648
649 /*
650  * This turns all merge entries into "stage 3". That guarantees that
651  * when we read in the new tree (into "stage 1"), we won't lose sight
652  * of the fact that we had unmerged entries.
653  */
654 static void mark_merge_entries(void)
655 {
656         int i;
657         for (i = 0; i < active_nr; i++) {
658                 struct cache_entry *ce = active_cache[i];
659                 if (!ce_stage(ce))
660                         continue;
661                 ce->ce_flags |= htons(CE_STAGEMASK);
662         }
663 }
664
665 int run_diff_index(struct rev_info *revs, int cached)
666 {
667         int ret;
668         struct object *ent;
669         struct tree *tree;
670         const char *tree_name;
671         int match_missing = 0;
672
673         /*
674          * Backward compatibility wart - "diff-index -m" does
675          * not mean "do not ignore merges", but totally different.
676          */
677         if (!revs->ignore_merges)
678                 match_missing = 1;
679
680         mark_merge_entries();
681
682         ent = revs->pending.objects[0].item;
683         tree_name = revs->pending.objects[0].name;
684         tree = parse_tree_indirect(ent->sha1);
685         if (!tree)
686                 return error("bad tree object %s", tree_name);
687         if (read_tree(tree, 1, revs->prune_data))
688                 return error("unable to read tree object %s", tree_name);
689         ret = diff_cache(revs, active_cache, active_nr, revs->prune_data,
690                          cached, match_missing);
691         diffcore_std(&revs->diffopt);
692         diff_flush(&revs->diffopt);
693         return ret;
694 }
695
696 int do_diff_cache(const unsigned char *tree_sha1, struct diff_options *opt)
697 {
698         struct tree *tree;
699         struct rev_info revs;
700         int i;
701         struct cache_entry **dst;
702         struct cache_entry *last = NULL;
703
704         /*
705          * This is used by git-blame to run diff-cache internally;
706          * it potentially needs to repeatedly run this, so we will
707          * start by removing the higher order entries the last round
708          * left behind.
709          */
710         dst = active_cache;
711         for (i = 0; i < active_nr; i++) {
712                 struct cache_entry *ce = active_cache[i];
713                 if (ce_stage(ce)) {
714                         if (last && !strcmp(ce->name, last->name))
715                                 continue;
716                         cache_tree_invalidate_path(active_cache_tree,
717                                                    ce->name);
718                         last = ce;
719                         ce->ce_mode = 0;
720                         ce->ce_flags &= ~htons(CE_STAGEMASK);
721                 }
722                 *dst++ = ce;
723         }
724         active_nr = dst - active_cache;
725
726         init_revisions(&revs, NULL);
727         revs.prune_data = opt->paths;
728         tree = parse_tree_indirect(tree_sha1);
729         if (!tree)
730                 die("bad tree object %s", sha1_to_hex(tree_sha1));
731         if (read_tree(tree, 1, opt->paths))
732                 return error("unable to read tree %s", sha1_to_hex(tree_sha1));
733         return diff_cache(&revs, active_cache, active_nr, revs.prune_data,
734                           1, 0);
735 }