remove delta-against-self bit
[git.git] / read-tree.c
1 /*
2  * GIT - The information manager from hell
3  *
4  * Copyright (C) Linus Torvalds, 2005
5  */
6 #define DBRT_DEBUG 1
7
8 #include "cache.h"
9
10 #include "object.h"
11 #include "tree.h"
12
13 static int merge = 0;
14 static int update = 0;
15 static int index_only = 0;
16 static int nontrivial_merge = 0;
17 static int trivial_merges_only = 0;
18 static int aggressive = 0;
19
20 static int head_idx = -1;
21 static int merge_size = 0;
22
23 static struct object_list *trees = NULL;
24
25 static struct cache_entry df_conflict_entry = { 
26 };
27
28 static struct tree_entry_list df_conflict_list = {
29         .name = NULL,
30         .next = &df_conflict_list
31 };
32
33 typedef int (*merge_fn_t)(struct cache_entry **src);
34
35 static int entcmp(char *name1, int dir1, char *name2, int dir2)
36 {
37         int len1 = strlen(name1);
38         int len2 = strlen(name2);
39         int len = len1 < len2 ? len1 : len2;
40         int ret = memcmp(name1, name2, len);
41         unsigned char c1, c2;
42         if (ret)
43                 return ret;
44         c1 = name1[len];
45         c2 = name2[len];
46         if (!c1 && dir1)
47                 c1 = '/';
48         if (!c2 && dir2)
49                 c2 = '/';
50         ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
51         if (c1 && c2 && !ret)
52                 ret = len1 - len2;
53         return ret;
54 }
55
56 static int unpack_trees_rec(struct tree_entry_list **posns, int len,
57                             const char *base, merge_fn_t fn, int *indpos)
58 {
59         int baselen = strlen(base);
60         int src_size = len + 1;
61         do {
62                 int i;
63                 char *first;
64                 int firstdir = 0;
65                 int pathlen;
66                 unsigned ce_size;
67                 struct tree_entry_list **subposns;
68                 struct cache_entry **src;
69                 int any_files = 0;
70                 int any_dirs = 0;
71                 char *cache_name;
72                 int ce_stage;
73
74                 /* Find the first name in the input. */
75
76                 first = NULL;
77                 cache_name = NULL;
78
79                 /* Check the cache */
80                 if (merge && *indpos < active_nr) {
81                         /* This is a bit tricky: */
82                         /* If the index has a subdirectory (with
83                          * contents) as the first name, it'll get a
84                          * filename like "foo/bar". But that's after
85                          * "foo", so the entry in trees will get
86                          * handled first, at which point we'll go into
87                          * "foo", and deal with "bar" from the index,
88                          * because the base will be "foo/". The only
89                          * way we can actually have "foo/bar" first of
90                          * all the things is if the trees don't
91                          * contain "foo" at all, in which case we'll
92                          * handle "foo/bar" without going into the
93                          * directory, but that's fine (and will return
94                          * an error anyway, with the added unknown
95                          * file case.
96                          */
97
98                         cache_name = active_cache[*indpos]->name;
99                         if (strlen(cache_name) > baselen &&
100                             !memcmp(cache_name, base, baselen)) {
101                                 cache_name += baselen;
102                                 first = cache_name;
103                         } else {
104                                 cache_name = NULL;
105                         }
106                 }
107
108 #if DBRT_DEBUG > 1
109                 if (first)
110                         printf("index %s\n", first);
111 #endif
112                 for (i = 0; i < len; i++) {
113                         if (!posns[i] || posns[i] == &df_conflict_list)
114                                 continue;
115 #if DBRT_DEBUG > 1
116                         printf("%d %s\n", i + 1, posns[i]->name);
117 #endif
118                         if (!first || entcmp(first, firstdir,
119                                              posns[i]->name, 
120                                              posns[i]->directory) > 0) {
121                                 first = posns[i]->name;
122                                 firstdir = posns[i]->directory;
123                         }
124                 }
125                 /* No name means we're done */
126                 if (!first)
127                         return 0;
128
129                 pathlen = strlen(first);
130                 ce_size = cache_entry_size(baselen + pathlen);
131
132                 src = xmalloc(sizeof(struct cache_entry *) * src_size);
133                 memset(src, 0, sizeof(struct cache_entry *) * src_size);
134
135                 subposns = xmalloc(sizeof(struct tree_list_entry *) * len);
136                 memset(subposns, 0, sizeof(struct tree_list_entry *) * len);
137
138                 if (cache_name && !strcmp(cache_name, first)) {
139                         any_files = 1;
140                         src[0] = active_cache[*indpos];
141                         remove_cache_entry_at(*indpos);
142                 }
143
144                 for (i = 0; i < len; i++) {
145                         struct cache_entry *ce;
146
147                         if (!posns[i] ||
148                             (posns[i] != &df_conflict_list &&
149                              strcmp(first, posns[i]->name))) {
150                                 continue;
151                         }
152
153                         if (posns[i] == &df_conflict_list) {
154                                 src[i + merge] = &df_conflict_entry;
155                                 continue;
156                         }
157
158                         if (posns[i]->directory) {
159                                 any_dirs = 1;
160                                 parse_tree(posns[i]->item.tree);
161                                 subposns[i] = posns[i]->item.tree->entries;
162                                 posns[i] = posns[i]->next;
163                                 src[i + merge] = &df_conflict_entry;
164                                 continue;
165                         }
166
167                         if (!merge)
168                                 ce_stage = 0;
169                         else if (i + 1 < head_idx)
170                                 ce_stage = 1;
171                         else if (i + 1 > head_idx)
172                                 ce_stage = 3;
173                         else
174                                 ce_stage = 2;
175
176                         ce = xmalloc(ce_size);
177                         memset(ce, 0, ce_size);
178                         ce->ce_mode = create_ce_mode(posns[i]->mode);
179                         ce->ce_flags = create_ce_flags(baselen + pathlen,
180                                                        ce_stage);
181                         memcpy(ce->name, base, baselen);
182                         memcpy(ce->name + baselen, first, pathlen + 1);
183
184                         any_files = 1;
185
186                         memcpy(ce->sha1, posns[i]->item.any->sha1, 20);
187                         src[i + merge] = ce;
188                         subposns[i] = &df_conflict_list;
189                         posns[i] = posns[i]->next;
190                 }
191                 if (any_files) {
192                         if (merge) {
193                                 int ret;
194
195 #if DBRT_DEBUG > 1
196                                 printf("%s:\n", first);
197                                 for (i = 0; i < src_size; i++) {
198                                         printf(" %d ", i);
199                                         if (src[i])
200                                                 printf("%s\n", sha1_to_hex(src[i]->sha1));
201                                         else
202                                                 printf("\n");
203                                 }
204 #endif
205                                 ret = fn(src);
206                                 
207 #if DBRT_DEBUG > 1
208                                 printf("Added %d entries\n", ret);
209 #endif
210                                 *indpos += ret;
211                         } else {
212                                 for (i = 0; i < src_size; i++) {
213                                         if (src[i]) {
214                                                 add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
215                                         }
216                                 }
217                         }
218                 }
219                 if (any_dirs) {
220                         char *newbase = xmalloc(baselen + 2 + pathlen);
221                         memcpy(newbase, base, baselen);
222                         memcpy(newbase + baselen, first, pathlen);
223                         newbase[baselen + pathlen] = '/';
224                         newbase[baselen + pathlen + 1] = '\0';
225                         if (unpack_trees_rec(subposns, len, newbase, fn,
226                                              indpos))
227                                 return -1;
228                         free(newbase);
229                 }
230                 free(subposns);
231                 free(src);
232         } while (1);
233 }
234
235 static void reject_merge(struct cache_entry *ce)
236 {
237         die("Entry '%s' would be overwritten by merge. Cannot merge.", 
238             ce->name);
239 }
240
241 /* Unlink the last component and attempt to remove leading
242  * directories, in case this unlink is the removal of the
243  * last entry in the directory -- empty directories are removed.
244  */
245 static void unlink_entry(char *name)
246 {
247         char *cp, *prev;
248
249         if (unlink(name))
250                 return;
251         prev = NULL;
252         while (1) {
253                 int status;
254                 cp = strrchr(name, '/');
255                 if (prev)
256                         *prev = '/';
257                 if (!cp)
258                         break;
259
260                 *cp = 0;
261                 status = rmdir(name);
262                 if (status) {
263                         *cp = '/';
264                         break;
265                 }
266                 prev = cp;
267         }
268 }
269
270 static void check_updates(struct cache_entry **src, int nr)
271 {
272         static struct checkout state = {
273                 .base_dir = "",
274                 .force = 1,
275                 .quiet = 1,
276                 .refresh_cache = 1,
277         };
278         unsigned short mask = htons(CE_UPDATE);
279         while (nr--) {
280                 struct cache_entry *ce = *src++;
281                 if (!ce->ce_mode) {
282                         if (update)
283                                 unlink_entry(ce->name);
284                         continue;
285                 }
286                 if (ce->ce_flags & mask) {
287                         ce->ce_flags &= ~mask;
288                         if (update)
289                                 checkout_entry(ce, &state);
290                 }
291         }
292 }
293
294 static int unpack_trees(merge_fn_t fn)
295 {
296         int indpos = 0;
297         unsigned len = object_list_length(trees);
298         struct tree_entry_list **posns;
299         int i;
300         struct object_list *posn = trees;
301         merge_size = len;
302
303         if (len) {
304                 posns = xmalloc(len * sizeof(struct tree_entry_list *));
305                 for (i = 0; i < len; i++) {
306                         posns[i] = ((struct tree *) posn->item)->entries;
307                         posn = posn->next;
308                 }
309                 if (unpack_trees_rec(posns, len, "", fn, &indpos))
310                         return -1;
311         }
312
313         if (trivial_merges_only && nontrivial_merge)
314                 die("Merge requires file-level merging");
315
316         check_updates(active_cache, active_nr);
317         return 0;
318 }
319
320 static int list_tree(unsigned char *sha1)
321 {
322         struct tree *tree = parse_tree_indirect(sha1);
323         if (!tree)
324                 return -1;
325         object_list_append(&tree->object, &trees);
326         return 0;
327 }
328
329 static int same(struct cache_entry *a, struct cache_entry *b)
330 {
331         if (!!a != !!b)
332                 return 0;
333         if (!a && !b)
334                 return 1;
335         return a->ce_mode == b->ce_mode && 
336                 !memcmp(a->sha1, b->sha1, 20);
337 }
338
339
340 /*
341  * When a CE gets turned into an unmerged entry, we
342  * want it to be up-to-date
343  */
344 static void verify_uptodate(struct cache_entry *ce)
345 {
346         struct stat st;
347
348         if (index_only)
349                 return;
350
351         if (!lstat(ce->name, &st)) {
352                 unsigned changed = ce_match_stat(ce, &st);
353                 if (!changed)
354                         return;
355                 errno = 0;
356         }
357         if (errno == ENOENT)
358                 return;
359         die("Entry '%s' not uptodate. Cannot merge.", ce->name);
360 }
361
362 static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
363 {
364         merge->ce_flags |= htons(CE_UPDATE);
365         if (old) {
366                 /*
367                  * See if we can re-use the old CE directly?
368                  * That way we get the uptodate stat info.
369                  *
370                  * This also removes the UPDATE flag on
371                  * a match.
372                  */
373                 if (same(old, merge)) {
374                         *merge = *old;
375                 } else {
376                         verify_uptodate(old);
377                 }
378         }
379         merge->ce_flags &= ~htons(CE_STAGEMASK);
380         add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
381         return 1;
382 }
383
384 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
385 {
386         if (old)
387                 verify_uptodate(old);
388         ce->ce_mode = 0;
389         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
390         return 1;
391 }
392
393 static int keep_entry(struct cache_entry *ce)
394 {
395         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
396         return 1;
397 }
398
399 #if DBRT_DEBUG
400 static void show_stage_entry(FILE *o,
401                              const char *label, const struct cache_entry *ce)
402 {
403         if (!ce)
404                 fprintf(o, "%s (missing)\n", label);
405         else
406                 fprintf(o, "%s%06o %s %d\t%s\n",
407                         label,
408                         ntohl(ce->ce_mode),
409                         sha1_to_hex(ce->sha1),
410                         ce_stage(ce),
411                         ce->name);
412 }
413 #endif
414
415 static int threeway_merge(struct cache_entry **stages)
416 {
417         struct cache_entry *index;
418         struct cache_entry *head; 
419         struct cache_entry *remote = stages[head_idx + 1];
420         int count;
421         int head_match = 0;
422         int remote_match = 0;
423
424         int df_conflict_head = 0;
425         int df_conflict_remote = 0;
426
427         int any_anc_missing = 0;
428         int no_anc_exists = 1;
429         int i;
430
431         for (i = 1; i < head_idx; i++) {
432                 if (!stages[i])
433                         any_anc_missing = 1;
434                 else
435                         no_anc_exists = 0;
436         }
437
438         index = stages[0];
439         head = stages[head_idx];
440
441         if (head == &df_conflict_entry) {
442                 df_conflict_head = 1;
443                 head = NULL;
444         }
445
446         if (remote == &df_conflict_entry) {
447                 df_conflict_remote = 1;
448                 remote = NULL;
449         }
450
451         /* First, if there's a #16 situation, note that to prevent #13
452          * and #14. 
453          */
454         if (!same(remote, head)) {
455                 for (i = 1; i < head_idx; i++) {
456                         if (same(stages[i], head)) {
457                                 head_match = i;
458                         }
459                         if (same(stages[i], remote)) {
460                                 remote_match = i;
461                         }
462                 }
463         }
464
465         /* We start with cases where the index is allowed to match
466          * something other than the head: #14(ALT) and #2ALT, where it
467          * is permitted to match the result instead.
468          */
469         /* #14, #14ALT, #2ALT */
470         if (remote && !df_conflict_head && head_match && !remote_match) {
471                 if (index && !same(index, remote) && !same(index, head))
472                         reject_merge(index);
473                 return merged_entry(remote, index);
474         }
475         /*
476          * If we have an entry in the index cache, then we want to
477          * make sure that it matches head.
478          */
479         if (index && !same(index, head)) {
480                 reject_merge(index);
481         }
482
483         if (head) {
484                 /* #5ALT, #15 */
485                 if (same(head, remote))
486                         return merged_entry(head, index);
487                 /* #13, #3ALT */
488                 if (!df_conflict_remote && remote_match && !head_match)
489                         return merged_entry(head, index);
490         }
491
492         /* #1 */
493         if (!head && !remote && any_anc_missing)
494                 return 0;
495
496         /* Under the new "aggressive" rule, we resolve mostly trivial
497          * cases that we historically had git-merge-one-file resolve.
498          */
499         if (aggressive) {
500                 int head_deleted = !head && !df_conflict_head;
501                 int remote_deleted = !remote && !df_conflict_remote;
502                 /*
503                  * Deleted in both.
504                  * Deleted in one and unchanged in the other.
505                  */
506                 if ((head_deleted && remote_deleted) ||
507                     (head_deleted && remote && remote_match) ||
508                     (remote_deleted && head && head_match))
509                         return 0;
510
511                 /*
512                  * Added in both, identically.
513                  */
514                 if (no_anc_exists && head && remote && same(head, remote))
515                         return merged_entry(head, index);
516
517         }
518
519         /* Below are "no merge" cases, which require that the index be
520          * up-to-date to avoid the files getting overwritten with
521          * conflict resolution files. 
522          */
523         if (index) {
524                 verify_uptodate(index);
525         }
526
527         nontrivial_merge = 1;
528
529         /* #2, #3, #4, #6, #7, #9, #11. */
530         count = 0;
531         if (!head_match || !remote_match) {
532                 for (i = 1; i < head_idx; i++) {
533                         if (stages[i]) {
534                                 keep_entry(stages[i]);
535                                 count++;
536                                 break;
537                         }
538                 }
539         }
540 #if DBRT_DEBUG
541         else {
542                 fprintf(stderr, "read-tree: warning #16 detected\n");
543                 show_stage_entry(stderr, "head   ", stages[head_match]);
544                 show_stage_entry(stderr, "remote ", stages[remote_match]);
545         }
546 #endif
547         if (head) { count += keep_entry(head); }
548         if (remote) { count += keep_entry(remote); }
549         return count;
550 }
551
552 /*
553  * Two-way merge.
554  *
555  * The rule is to "carry forward" what is in the index without losing
556  * information across a "fast forward", favoring a successful merge
557  * over a merge failure when it makes sense.  For details of the
558  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
559  *
560  */
561 static int twoway_merge(struct cache_entry **src)
562 {
563         struct cache_entry *current = src[0];
564         struct cache_entry *oldtree = src[1], *newtree = src[2];
565
566         if (merge_size != 2)
567                 return error("Cannot do a twoway merge of %d trees\n",
568                              merge_size);
569
570         if (current) {
571                 if ((!oldtree && !newtree) || /* 4 and 5 */
572                     (!oldtree && newtree &&
573                      same(current, newtree)) || /* 6 and 7 */
574                     (oldtree && newtree &&
575                      same(oldtree, newtree)) || /* 14 and 15 */
576                     (oldtree && newtree &&
577                      !same(oldtree, newtree) && /* 18 and 19*/
578                      same(current, newtree))) {
579                         return keep_entry(current);
580                 }
581                 else if (oldtree && !newtree && same(current, oldtree)) {
582                         /* 10 or 11 */
583                         return deleted_entry(oldtree, current);
584                 }
585                 else if (oldtree && newtree &&
586                          same(current, oldtree) && !same(current, newtree)) {
587                         /* 20 or 21 */
588                         return merged_entry(newtree, current);
589                 }
590                 else {
591                         /* all other failures */
592                         if (oldtree)
593                                 reject_merge(oldtree);
594                         if (current)
595                                 reject_merge(current);
596                         if (newtree)
597                                 reject_merge(newtree);
598                         return -1;
599                 }
600         }
601         else if (newtree)
602                 return merged_entry(newtree, current);
603         else
604                 return deleted_entry(oldtree, current);
605 }
606
607 /*
608  * One-way merge.
609  *
610  * The rule is:
611  * - take the stat information from stage0, take the data from stage1
612  */
613 static int oneway_merge(struct cache_entry **src)
614 {
615         struct cache_entry *old = src[0];
616         struct cache_entry *a = src[1];
617
618         if (merge_size != 1)
619                 return error("Cannot do a oneway merge of %d trees\n",
620                              merge_size);
621
622         if (!a)
623                 return 0;
624         if (old && same(old, a)) {
625                 return keep_entry(old);
626         }
627         return merged_entry(a, NULL);
628 }
629
630 static int read_cache_unmerged(void)
631 {
632         int i, deleted;
633         struct cache_entry **dst;
634
635         read_cache();
636         dst = active_cache;
637         deleted = 0;
638         for (i = 0; i < active_nr; i++) {
639                 struct cache_entry *ce = active_cache[i];
640                 if (ce_stage(ce)) {
641                         deleted++;
642                         continue;
643                 }
644                 if (deleted)
645                         *dst = ce;
646                 dst++;
647         }
648         active_nr -= deleted;
649         return deleted;
650 }
651
652 static const char read_tree_usage[] = "git-read-tree (<sha> | -m [-u | -i] <sha1> [<sha2> [<sha3>]])";
653
654 static struct cache_file cache_file;
655
656 int main(int argc, char **argv)
657 {
658         int i, newfd, reset, stage = 0;
659         unsigned char sha1[20];
660         merge_fn_t fn = NULL;
661
662         setup_git_directory();
663
664         newfd = hold_index_file_for_update(&cache_file, get_index_file());
665         if (newfd < 0)
666                 die("unable to create new cachefile");
667
668         git_config(git_default_config);
669
670         merge = 0;
671         reset = 0;
672         for (i = 1; i < argc; i++) {
673                 const char *arg = argv[i];
674
675                 /* "-u" means "update", meaning that a merge will update
676                  * the working tree.
677                  */
678                 if (!strcmp(arg, "-u")) {
679                         update = 1;
680                         continue;
681                 }
682
683                 /* "-i" means "index only", meaning that a merge will
684                  * not even look at the working tree.
685                  */
686                 if (!strcmp(arg, "-i")) {
687                         index_only = 1;
688                         continue;
689                 }
690
691                 /* This differs from "-m" in that we'll silently ignore unmerged entries */
692                 if (!strcmp(arg, "--reset")) {
693                         if (stage || merge)
694                                 usage(read_tree_usage);
695                         reset = 1;
696                         merge = 1;
697                         stage = 1;
698                         read_cache_unmerged();
699                         continue;
700                 }
701
702                 if (!strcmp(arg, "--trivial")) {
703                         trivial_merges_only = 1;
704                         continue;
705                 }
706
707                 if (!strcmp(arg, "--aggressive")) {
708                         aggressive = 1;
709                         continue;
710                 }
711
712                 /* "-m" stands for "merge", meaning we start in stage 1 */
713                 if (!strcmp(arg, "-m")) {
714                         if (stage || merge)
715                                 usage(read_tree_usage);
716                         if (read_cache_unmerged())
717                                 die("you need to resolve your current index first");
718                         stage = 1;
719                         merge = 1;
720                         continue;
721                 }
722
723                 /* using -u and -i at the same time makes no sense */
724                 if (1 < index_only + update)
725                         usage(read_tree_usage);
726
727                 if (get_sha1(arg, sha1) < 0)
728                         usage(read_tree_usage);
729                 if (list_tree(sha1) < 0)
730                         die("failed to unpack tree object %s", arg);
731                 stage++;
732         }
733         if ((update||index_only) && !merge)
734                 usage(read_tree_usage);
735
736         if (merge) {
737                 if (stage < 2)
738                         die("just how do you expect me to merge %d trees?", stage-1);
739                 switch (stage - 1) {
740                 case 1:
741                         fn = oneway_merge;
742                         break;
743                 case 2:
744                         fn = twoway_merge;
745                         break;
746                 case 3:
747                         fn = threeway_merge;
748                         break;
749                 default:
750                         fn = threeway_merge;
751                         break;
752                 }
753
754                 if (stage - 1 >= 3)
755                         head_idx = stage - 2;
756                 else
757                         head_idx = 1;
758         }
759
760         unpack_trees(fn);
761         if (write_cache(newfd, active_cache, active_nr) ||
762             commit_index_file(&cache_file))
763                 die("unable to write new index file");
764         return 0;
765 }