Make 'unpack_trees()' have a separate source and destination index
[git/git.git] / unpack-trees.c
1 #define NO_THE_INDEX_COMPATIBILITY_MACROS
2 #include "cache.h"
3 #include "dir.h"
4 #include "tree.h"
5 #include "tree-walk.h"
6 #include "cache-tree.h"
7 #include "unpack-trees.h"
8 #include "progress.h"
9 #include "refs.h"
10
11 static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
12 unsigned int set, unsigned int clear)
13 {
14 unsigned int size = ce_size(ce);
15 struct cache_entry *new = xmalloc(size);
16
17 clear |= CE_HASHED | CE_UNHASHED;
18
19 memcpy(new, ce, size);
20 new->next = NULL;
21 new->ce_flags = (new->ce_flags & ~clear) | set;
22 add_index_entry(&o->result, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE|ADD_CACHE_SKIP_DFCHECK);
23 }
24
25 /* Unlink the last component and attempt to remove leading
26 * directories, in case this unlink is the removal of the
27 * last entry in the directory -- empty directories are removed.
28 */
29 static void unlink_entry(char *name, char *last_symlink)
30 {
31 char *cp, *prev;
32
33 if (has_symlink_leading_path(name, last_symlink))
34 return;
35 if (unlink(name))
36 return;
37 prev = NULL;
38 while (1) {
39 int status;
40 cp = strrchr(name, '/');
41 if (prev)
42 *prev = '/';
43 if (!cp)
44 break;
45
46 *cp = 0;
47 status = rmdir(name);
48 if (status) {
49 *cp = '/';
50 break;
51 }
52 prev = cp;
53 }
54 }
55
56 static struct checkout state;
57 static void check_updates(struct unpack_trees_options *o)
58 {
59 unsigned cnt = 0, total = 0;
60 struct progress *progress = NULL;
61 char last_symlink[PATH_MAX];
62 struct index_state *index = &o->result;
63 int i;
64
65 if (o->update && o->verbose_update) {
66 for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
67 struct cache_entry *ce = index->cache[cnt];
68 if (ce->ce_flags & (CE_UPDATE | CE_REMOVE))
69 total++;
70 }
71
72 progress = start_progress_delay("Checking out files",
73 total, 50, 1);
74 cnt = 0;
75 }
76
77 *last_symlink = '\0';
78 for (i = 0; i < index->cache_nr; i++) {
79 struct cache_entry *ce = index->cache[i];
80
81 if (ce->ce_flags & (CE_UPDATE | CE_REMOVE))
82 display_progress(progress, ++cnt);
83 if (ce->ce_flags & CE_REMOVE) {
84 if (o->update)
85 unlink_entry(ce->name, last_symlink);
86 remove_index_entry_at(&o->result, i);
87 i--;
88 continue;
89 }
90 if (ce->ce_flags & CE_UPDATE) {
91 ce->ce_flags &= ~CE_UPDATE;
92 if (o->update) {
93 checkout_entry(ce, &state, NULL);
94 *last_symlink = '\0';
95 }
96 }
97 }
98 stop_progress(&progress);
99 }
100
101 static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
102 {
103 int ret = o->fn(src, o);
104 if (ret > 0)
105 ret = 0;
106 return ret;
107 }
108
109 static int unpack_index_entry(struct cache_entry *ce, struct unpack_trees_options *o)
110 {
111 struct cache_entry *src[5] = { ce, };
112
113 o->pos++;
114 if (ce_stage(ce)) {
115 if (o->skip_unmerged) {
116 add_entry(o, ce, 0, 0);
117 return 0;
118 }
119 return 0;
120 }
121 return call_unpack_fn(src, o);
122 }
123
124 int traverse_trees_recursive(int n, unsigned long dirmask, unsigned long df_conflicts, struct name_entry *names, struct traverse_info *info)
125 {
126 int i;
127 struct tree_desc t[3];
128 struct traverse_info newinfo;
129 struct name_entry *p;
130
131 p = names;
132 while (!p->mode)
133 p++;
134
135 newinfo = *info;
136 newinfo.prev = info;
137 newinfo.name = *p;
138 newinfo.pathlen += tree_entry_len(p->path, p->sha1) + 1;
139 newinfo.conflicts |= df_conflicts;
140
141 for (i = 0; i < n; i++, dirmask >>= 1) {
142 const unsigned char *sha1 = NULL;
143 if (dirmask & 1)
144 sha1 = names[i].sha1;
145 fill_tree_descriptor(t+i, sha1);
146 }
147 traverse_trees(n, t, &newinfo);
148 return 0;
149 }
150
151 /*
152 * Compare the traverse-path to the cache entry without actually
153 * having to generate the textual representation of the traverse
154 * path.
155 *
156 * NOTE! This *only* compares up to the size of the traverse path
157 * itself - the caller needs to do the final check for the cache
158 * entry having more data at the end!
159 */
160 static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
161 {
162 int len, pathlen, ce_len;
163 const char *ce_name;
164
165 if (info->prev) {
166 int cmp = do_compare_entry(ce, info->prev, &info->name);
167 if (cmp)
168 return cmp;
169 }
170 pathlen = info->pathlen;
171 ce_len = ce_namelen(ce);
172
173 /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
174 if (ce_len < pathlen)
175 return -1;
176
177 ce_len -= pathlen;
178 ce_name = ce->name + pathlen;
179
180 len = tree_entry_len(n->path, n->sha1);
181 return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
182 }
183
184 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
185 {
186 int cmp = do_compare_entry(ce, info, n);
187 if (cmp)
188 return cmp;
189
190 /*
191 * Even if the beginning compared identically, the ce should
192 * compare as bigger than a directory leading up to it!
193 */
194 return ce_namelen(ce) > traverse_path_len(info, n);
195 }
196
197 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
198 {
199 int len = traverse_path_len(info, n);
200 struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
201
202 ce->ce_mode = create_ce_mode(n->mode);
203 ce->ce_flags = create_ce_flags(len, stage);
204 hashcpy(ce->sha1, n->sha1);
205 make_traverse_path(ce->name, info, n);
206
207 return ce;
208 }
209
210 static int unpack_nondirectories(int n, unsigned long mask, unsigned long dirmask, struct cache_entry *src[5],
211 const struct name_entry *names, const struct traverse_info *info)
212 {
213 int i;
214 struct unpack_trees_options *o = info->data;
215 unsigned long conflicts;
216
217 /* Do we have *only* directories? Nothing to do */
218 if (mask == dirmask && !src[0])
219 return 0;
220
221 conflicts = info->conflicts;
222 if (o->merge)
223 conflicts >>= 1;
224 conflicts |= dirmask;
225
226 /*
227 * Ok, we've filled in up to any potential index entry in src[0],
228 * now do the rest.
229 */
230 for (i = 0; i < n; i++) {
231 int stage;
232 unsigned int bit = 1ul << i;
233 if (conflicts & bit) {
234 src[i + o->merge] = o->df_conflict_entry;
235 continue;
236 }
237 if (!(mask & bit))
238 continue;
239 if (!o->merge)
240 stage = 0;
241 else if (i + 1 < o->head_idx)
242 stage = 1;
243 else if (i + 1 > o->head_idx)
244 stage = 3;
245 else
246 stage = 2;
247 src[i + o->merge] = create_ce_entry(info, names + i, stage);
248 }
249
250 if (o->merge)
251 return call_unpack_fn(src, o);
252
253 n += o->merge;
254 for (i = 0; i < n; i++)
255 add_entry(o, src[i], 0, 0);
256 return 0;
257 }
258
259 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
260 {
261 struct cache_entry *src[5] = { NULL, };
262 struct unpack_trees_options *o = info->data;
263 const struct name_entry *p = names;
264
265 /* Find first entry with a real name (we could use "mask" too) */
266 while (!p->mode)
267 p++;
268
269 /* Are we supposed to look at the index too? */
270 if (o->merge) {
271 while (o->pos < o->src_index->cache_nr) {
272 struct cache_entry *ce = o->src_index->cache[o->pos];
273 int cmp = compare_entry(ce, info, p);
274 if (cmp < 0) {
275 if (unpack_index_entry(ce, o) < 0)
276 return -1;
277 continue;
278 }
279 if (!cmp) {
280 o->pos++;
281 if (ce_stage(ce)) {
282 /*
283 * If we skip unmerged index entries, we'll skip this
284 * entry *and* the tree entries associated with it!
285 */
286 if (o->skip_unmerged) {
287 add_entry(o, ce, 0, 0);
288 return mask;
289 }
290 continue;
291 }
292 src[0] = ce;
293 }
294 break;
295 }
296 }
297
298 if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
299 return -1;
300
301 /* Now handle any directories.. */
302 if (dirmask) {
303 unsigned long conflicts = mask & ~dirmask;
304 if (o->merge) {
305 conflicts <<= 1;
306 if (src[0])
307 conflicts |= 1;
308 }
309 traverse_trees_recursive(n, dirmask, conflicts, names, info);
310 return mask;
311 }
312
313 return mask;
314 }
315
316 static int unpack_failed(struct unpack_trees_options *o, const char *message)
317 {
318 if (!o->gently) {
319 if (message)
320 return error(message);
321 return -1;
322 }
323 return -1;
324 }
325
326 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
327 {
328 static struct cache_entry *dfc;
329
330 if (len > 4)
331 die("unpack_trees takes at most four trees");
332 memset(&state, 0, sizeof(state));
333 state.base_dir = "";
334 state.force = 1;
335 state.quiet = 1;
336 state.refresh_cache = 1;
337
338 memset(&o->result, 0, sizeof(o->result));
339 o->merge_size = len;
340
341 if (!dfc)
342 dfc = xcalloc(1, sizeof(struct cache_entry) + 1);
343 o->df_conflict_entry = dfc;
344
345 if (len) {
346 const char *prefix = o->prefix ? o->prefix : "";
347 struct traverse_info info;
348
349 setup_traverse_info(&info, prefix);
350 info.fn = unpack_callback;
351 info.data = o;
352
353 if (traverse_trees(len, t, &info) < 0)
354 return unpack_failed(o, NULL);
355 }
356
357 /* Any left-over entries in the index? */
358 if (o->merge) {
359 while (o->pos < o->src_index->cache_nr) {
360 struct cache_entry *ce = o->src_index->cache[o->pos];
361 if (unpack_index_entry(ce, o) < 0)
362 return unpack_failed(o, NULL);
363 }
364 }
365
366 if (o->trivial_merges_only && o->nontrivial_merge)
367 return unpack_failed(o, "Merge requires file-level merging");
368
369 o->src_index = NULL;
370 check_updates(o);
371 if (o->dst_index)
372 *o->dst_index = o->result;
373 return 0;
374 }
375
376 /* Here come the merge functions */
377
378 static int reject_merge(struct cache_entry *ce)
379 {
380 return error("Entry '%s' would be overwritten by merge. Cannot merge.",
381 ce->name);
382 }
383
384 static int same(struct cache_entry *a, struct cache_entry *b)
385 {
386 if (!!a != !!b)
387 return 0;
388 if (!a && !b)
389 return 1;
390 return a->ce_mode == b->ce_mode &&
391 !hashcmp(a->sha1, b->sha1);
392 }
393
394
395 /*
396 * When a CE gets turned into an unmerged entry, we
397 * want it to be up-to-date
398 */
399 static int verify_uptodate(struct cache_entry *ce,
400 struct unpack_trees_options *o)
401 {
402 struct stat st;
403
404 if (o->index_only || o->reset)
405 return 0;
406
407 if (!lstat(ce->name, &st)) {
408 unsigned changed = ie_match_stat(o->src_index, ce, &st, CE_MATCH_IGNORE_VALID);
409 if (!changed)
410 return 0;
411 /*
412 * NEEDSWORK: the current default policy is to allow
413 * submodule to be out of sync wrt the supermodule
414 * index. This needs to be tightened later for
415 * submodules that are marked to be automatically
416 * checked out.
417 */
418 if (S_ISGITLINK(ce->ce_mode))
419 return 0;
420 errno = 0;
421 }
422 if (errno == ENOENT)
423 return 0;
424 return o->gently ? -1 :
425 error("Entry '%s' not uptodate. Cannot merge.", ce->name);
426 }
427
428 static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
429 {
430 if (ce)
431 cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
432 }
433
434 /*
435 * Check that checking out ce->sha1 in subdir ce->name is not
436 * going to overwrite any working files.
437 *
438 * Currently, git does not checkout subprojects during a superproject
439 * checkout, so it is not going to overwrite anything.
440 */
441 static int verify_clean_submodule(struct cache_entry *ce, const char *action,
442 struct unpack_trees_options *o)
443 {
444 return 0;
445 }
446
447 static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
448 struct unpack_trees_options *o)
449 {
450 /*
451 * we are about to extract "ce->name"; we would not want to lose
452 * anything in the existing directory there.
453 */
454 int namelen;
455 int pos, i;
456 struct dir_struct d;
457 char *pathbuf;
458 int cnt = 0;
459 unsigned char sha1[20];
460
461 if (S_ISGITLINK(ce->ce_mode) &&
462 resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
463 /* If we are not going to update the submodule, then
464 * we don't care.
465 */
466 if (!hashcmp(sha1, ce->sha1))
467 return 0;
468 return verify_clean_submodule(ce, action, o);
469 }
470
471 /*
472 * First let's make sure we do not have a local modification
473 * in that directory.
474 */
475 namelen = strlen(ce->name);
476 pos = index_name_pos(o->src_index, ce->name, namelen);
477 if (0 <= pos)
478 return cnt; /* we have it as nondirectory */
479 pos = -pos - 1;
480 for (i = pos; i < o->src_index->cache_nr; i++) {
481 struct cache_entry *ce = o->src_index->cache[i];
482 int len = ce_namelen(ce);
483 if (len < namelen ||
484 strncmp(ce->name, ce->name, namelen) ||
485 ce->name[namelen] != '/')
486 break;
487 /*
488 * ce->name is an entry in the subdirectory.
489 */
490 if (!ce_stage(ce)) {
491 if (verify_uptodate(ce, o))
492 return -1;
493 add_entry(o, ce, CE_REMOVE, 0);
494 }
495 cnt++;
496 }
497
498 /*
499 * Then we need to make sure that we do not lose a locally
500 * present file that is not ignored.
501 */
502 pathbuf = xmalloc(namelen + 2);
503 memcpy(pathbuf, ce->name, namelen);
504 strcpy(pathbuf+namelen, "/");
505
506 memset(&d, 0, sizeof(d));
507 if (o->dir)
508 d.exclude_per_dir = o->dir->exclude_per_dir;
509 i = read_directory(&d, ce->name, pathbuf, namelen+1, NULL);
510 if (i)
511 return o->gently ? -1 :
512 error("Updating '%s' would lose untracked files in it",
513 ce->name);
514 free(pathbuf);
515 return cnt;
516 }
517
518 /*
519 * We do not want to remove or overwrite a working tree file that
520 * is not tracked, unless it is ignored.
521 */
522 static int verify_absent(struct cache_entry *ce, const char *action,
523 struct unpack_trees_options *o)
524 {
525 struct stat st;
526
527 if (o->index_only || o->reset || !o->update)
528 return 0;
529
530 if (has_symlink_leading_path(ce->name, NULL))
531 return 0;
532
533 if (!lstat(ce->name, &st)) {
534 int cnt;
535 int dtype = ce_to_dtype(ce);
536
537 if (o->dir && excluded(o->dir, ce->name, &dtype))
538 /*
539 * ce->name is explicitly excluded, so it is Ok to
540 * overwrite it.
541 */
542 return 0;
543 if (S_ISDIR(st.st_mode)) {
544 /*
545 * We are checking out path "foo" and
546 * found "foo/." in the working tree.
547 * This is tricky -- if we have modified
548 * files that are in "foo/" we would lose
549 * it.
550 */
551 cnt = verify_clean_subdirectory(ce, action, o);
552
553 /*
554 * If this removed entries from the index,
555 * what that means is:
556 *
557 * (1) the caller unpack_trees_rec() saw path/foo
558 * in the index, and it has not removed it because
559 * it thinks it is handling 'path' as blob with
560 * D/F conflict;
561 * (2) we will return "ok, we placed a merged entry
562 * in the index" which would cause o->pos to be
563 * incremented by one;
564 * (3) however, original o->pos now has 'path/foo'
565 * marked with "to be removed".
566 *
567 * We need to increment it by the number of
568 * deleted entries here.
569 */
570 o->pos += cnt;
571 return 0;
572 }
573
574 /*
575 * The previous round may already have decided to
576 * delete this path, which is in a subdirectory that
577 * is being replaced with a blob.
578 */
579 cnt = index_name_pos(&o->result, ce->name, strlen(ce->name));
580 if (0 <= cnt) {
581 struct cache_entry *ce = o->result.cache[cnt];
582 if (ce->ce_flags & CE_REMOVE)
583 return 0;
584 }
585
586 return o->gently ? -1 :
587 error("Untracked working tree file '%s' "
588 "would be %s by merge.", ce->name, action);
589 }
590 return 0;
591 }
592
593 static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
594 struct unpack_trees_options *o)
595 {
596 if (old) {
597 /*
598 * See if we can re-use the old CE directly?
599 * That way we get the uptodate stat info.
600 *
601 * This also removes the UPDATE flag on
602 * a match.
603 */
604 if (same(old, merge)) {
605 copy_cache_entry(merge, old);
606 } else {
607 if (verify_uptodate(old, o))
608 return -1;
609 invalidate_ce_path(old, o);
610 }
611 }
612 else {
613 if (verify_absent(merge, "overwritten", o))
614 return -1;
615 invalidate_ce_path(merge, o);
616 }
617
618 add_entry(o, merge, CE_UPDATE, CE_STAGEMASK);
619 return 1;
620 }
621
622 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
623 struct unpack_trees_options *o)
624 {
625 /* Did it exist in the index? */
626 if (!old) {
627 if (verify_absent(ce, "removed", o))
628 return -1;
629 return 0;
630 }
631 if (verify_uptodate(old, o))
632 return -1;
633 add_entry(o, ce, CE_REMOVE, 0);
634 invalidate_ce_path(ce, o);
635 return 1;
636 }
637
638 static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
639 {
640 add_entry(o, ce, 0, 0);
641 return 1;
642 }
643
644 #if DBRT_DEBUG
645 static void show_stage_entry(FILE *o,
646 const char *label, const struct cache_entry *ce)
647 {
648 if (!ce)
649 fprintf(o, "%s (missing)\n", label);
650 else
651 fprintf(o, "%s%06o %s %d\t%s\n",
652 label,
653 ce->ce_mode,
654 sha1_to_hex(ce->sha1),
655 ce_stage(ce),
656 ce->name);
657 }
658 #endif
659
660 int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
661 {
662 struct cache_entry *index;
663 struct cache_entry *head;
664 struct cache_entry *remote = stages[o->head_idx + 1];
665 int count;
666 int head_match = 0;
667 int remote_match = 0;
668
669 int df_conflict_head = 0;
670 int df_conflict_remote = 0;
671
672 int any_anc_missing = 0;
673 int no_anc_exists = 1;
674 int i;
675
676 for (i = 1; i < o->head_idx; i++) {
677 if (!stages[i] || stages[i] == o->df_conflict_entry)
678 any_anc_missing = 1;
679 else
680 no_anc_exists = 0;
681 }
682
683 index = stages[0];
684 head = stages[o->head_idx];
685
686 if (head == o->df_conflict_entry) {
687 df_conflict_head = 1;
688 head = NULL;
689 }
690
691 if (remote == o->df_conflict_entry) {
692 df_conflict_remote = 1;
693 remote = NULL;
694 }
695
696 /* First, if there's a #16 situation, note that to prevent #13
697 * and #14.
698 */
699 if (!same(remote, head)) {
700 for (i = 1; i < o->head_idx; i++) {
701 if (same(stages[i], head)) {
702 head_match = i;
703 }
704 if (same(stages[i], remote)) {
705 remote_match = i;
706 }
707 }
708 }
709
710 /* We start with cases where the index is allowed to match
711 * something other than the head: #14(ALT) and #2ALT, where it
712 * is permitted to match the result instead.
713 */
714 /* #14, #14ALT, #2ALT */
715 if (remote && !df_conflict_head && head_match && !remote_match) {
716 if (index && !same(index, remote) && !same(index, head))
717 return o->gently ? -1 : reject_merge(index);
718 return merged_entry(remote, index, o);
719 }
720 /*
721 * If we have an entry in the index cache, then we want to
722 * make sure that it matches head.
723 */
724 if (index && !same(index, head))
725 return o->gently ? -1 : reject_merge(index);
726
727 if (head) {
728 /* #5ALT, #15 */
729 if (same(head, remote))
730 return merged_entry(head, index, o);
731 /* #13, #3ALT */
732 if (!df_conflict_remote && remote_match && !head_match)
733 return merged_entry(head, index, o);
734 }
735
736 /* #1 */
737 if (!head && !remote && any_anc_missing)
738 return 0;
739
740 /* Under the new "aggressive" rule, we resolve mostly trivial
741 * cases that we historically had git-merge-one-file resolve.
742 */
743 if (o->aggressive) {
744 int head_deleted = !head && !df_conflict_head;
745 int remote_deleted = !remote && !df_conflict_remote;
746 struct cache_entry *ce = NULL;
747
748 if (index)
749 ce = index;
750 else if (head)
751 ce = head;
752 else if (remote)
753 ce = remote;
754 else {
755 for (i = 1; i < o->head_idx; i++) {
756 if (stages[i] && stages[i] != o->df_conflict_entry) {
757 ce = stages[i];
758 break;
759 }
760 }
761 }
762
763 /*
764 * Deleted in both.
765 * Deleted in one and unchanged in the other.
766 */
767 if ((head_deleted && remote_deleted) ||
768 (head_deleted && remote && remote_match) ||
769 (remote_deleted && head && head_match)) {
770 if (index)
771 return deleted_entry(index, index, o);
772 if (ce && !head_deleted) {
773 if (verify_absent(ce, "removed", o))
774 return -1;
775 }
776 return 0;
777 }
778 /*
779 * Added in both, identically.
780 */
781 if (no_anc_exists && head && remote && same(head, remote))
782 return merged_entry(head, index, o);
783
784 }
785
786 /* Below are "no merge" cases, which require that the index be
787 * up-to-date to avoid the files getting overwritten with
788 * conflict resolution files.
789 */
790 if (index) {
791 if (verify_uptodate(index, o))
792 return -1;
793 }
794
795 o->nontrivial_merge = 1;
796
797 /* #2, #3, #4, #6, #7, #9, #10, #11. */
798 count = 0;
799 if (!head_match || !remote_match) {
800 for (i = 1; i < o->head_idx; i++) {
801 if (stages[i] && stages[i] != o->df_conflict_entry) {
802 keep_entry(stages[i], o);
803 count++;
804 break;
805 }
806 }
807 }
808 #if DBRT_DEBUG
809 else {
810 fprintf(stderr, "read-tree: warning #16 detected\n");
811 show_stage_entry(stderr, "head ", stages[head_match]);
812 show_stage_entry(stderr, "remote ", stages[remote_match]);
813 }
814 #endif
815 if (head) { count += keep_entry(head, o); }
816 if (remote) { count += keep_entry(remote, o); }
817 return count;
818 }
819
820 /*
821 * Two-way merge.
822 *
823 * The rule is to "carry forward" what is in the index without losing
824 * information across a "fast forward", favoring a successful merge
825 * over a merge failure when it makes sense. For details of the
826 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
827 *
828 */
829 int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
830 {
831 struct cache_entry *current = src[0];
832 struct cache_entry *oldtree = src[1];
833 struct cache_entry *newtree = src[2];
834
835 if (o->merge_size != 2)
836 return error("Cannot do a twoway merge of %d trees",
837 o->merge_size);
838
839 if (oldtree == o->df_conflict_entry)
840 oldtree = NULL;
841 if (newtree == o->df_conflict_entry)
842 newtree = NULL;
843
844 if (current) {
845 if ((!oldtree && !newtree) || /* 4 and 5 */
846 (!oldtree && newtree &&
847 same(current, newtree)) || /* 6 and 7 */
848 (oldtree && newtree &&
849 same(oldtree, newtree)) || /* 14 and 15 */
850 (oldtree && newtree &&
851 !same(oldtree, newtree) && /* 18 and 19 */
852 same(current, newtree))) {
853 return keep_entry(current, o);
854 }
855 else if (oldtree && !newtree && same(current, oldtree)) {
856 /* 10 or 11 */
857 return deleted_entry(oldtree, current, o);
858 }
859 else if (oldtree && newtree &&
860 same(current, oldtree) && !same(current, newtree)) {
861 /* 20 or 21 */
862 return merged_entry(newtree, current, o);
863 }
864 else {
865 /* all other failures */
866 if (oldtree)
867 return o->gently ? -1 : reject_merge(oldtree);
868 if (current)
869 return o->gently ? -1 : reject_merge(current);
870 if (newtree)
871 return o->gently ? -1 : reject_merge(newtree);
872 return -1;
873 }
874 }
875 else if (newtree)
876 return merged_entry(newtree, current, o);
877 return deleted_entry(oldtree, current, o);
878 }
879
880 /*
881 * Bind merge.
882 *
883 * Keep the index entries at stage0, collapse stage1 but make sure
884 * stage0 does not have anything there.
885 */
886 int bind_merge(struct cache_entry **src,
887 struct unpack_trees_options *o)
888 {
889 struct cache_entry *old = src[0];
890 struct cache_entry *a = src[1];
891
892 if (o->merge_size != 1)
893 return error("Cannot do a bind merge of %d trees\n",
894 o->merge_size);
895 if (a && old)
896 return o->gently ? -1 :
897 error("Entry '%s' overlaps with '%s'. Cannot bind.", a->name, old->name);
898 if (!a)
899 return keep_entry(old, o);
900 else
901 return merged_entry(a, NULL, o);
902 }
903
904 /*
905 * One-way merge.
906 *
907 * The rule is:
908 * - take the stat information from stage0, take the data from stage1
909 */
910 int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
911 {
912 struct cache_entry *old = src[0];
913 struct cache_entry *a = src[1];
914
915 if (o->merge_size != 1)
916 return error("Cannot do a oneway merge of %d trees",
917 o->merge_size);
918
919 if (!a)
920 return deleted_entry(old, old, o);
921
922 if (old && same(old, a)) {
923 int update = 0;
924 if (o->reset) {
925 struct stat st;
926 if (lstat(old->name, &st) ||
927 ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID))
928 update |= CE_UPDATE;
929 }
930 add_entry(o, old, update, 0);
931 return 0;
932 }
933 return merged_entry(a, old, o);
934 }