1#include "cache.h"
2#include "dir.h"
3#include "tree.h"
4#include "tree-walk.h"
5#include "cache-tree.h"
6#include "unpack-trees.h"
7#include "progress.h"
8#include "refs.h"
9#define DBRT_DEBUG 1
11struct tree_entry_list {
13 struct tree_entry_list *next;
14 unsigned int mode;
15 const char *name;
16 const unsigned char *sha1;
17};
18static struct tree_entry_list *create_tree_entry_list(struct tree_desc *desc)
20{
21 struct name_entry one;
22 struct tree_entry_list *ret = NULL;
23 struct tree_entry_list **list_p = &ret;
24 while (tree_entry(desc, &one)) {
26 struct tree_entry_list *entry;
27 entry = xmalloc(sizeof(struct tree_entry_list));
29 entry->name = one.path;
30 entry->sha1 = one.sha1;
31 entry->mode = one.mode;
32 entry->next = NULL;
33 *list_p = entry;
35 list_p = &entry->next;
36 }
37 return ret;
38}
39static int entcmp(const char *name1, int dir1, const char *name2, int dir2)
41{
42 int len1 = strlen(name1);
43 int len2 = strlen(name2);
44 int len = len1 < len2 ? len1 : len2;
45 int ret = memcmp(name1, name2, len);
46 unsigned char c1, c2;
47 if (ret)
48 return ret;
49 c1 = name1[len];
50 c2 = name2[len];
51 if (!c1 && dir1)
52 c1 = '/';
53 if (!c2 && dir2)
54 c2 = '/';
55 ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
56 if (c1 && c2 && !ret)
57 ret = len1 - len2;
58 return ret;
59}
60static inline void remove_entry(int remove)
62{
63 if (remove >= 0)
64 remove_cache_entry_at(remove);
65}
66static int unpack_trees_rec(struct tree_entry_list **posns, int len,
68 const char *base, struct unpack_trees_options *o,
69 struct tree_entry_list *df_conflict_list)
70{
71 int remove;
72 int baselen = strlen(base);
73 int src_size = len + 1;
74 int retval = 0;
75 do {
77 int i;
78 const char *first;
79 int firstdir = 0;
80 int pathlen;
81 unsigned ce_size;
82 struct tree_entry_list **subposns;
83 struct cache_entry **src;
84 int any_files = 0;
85 int any_dirs = 0;
86 char *cache_name;
87 int ce_stage;
88 int skip_entry = 0;
89 /* Find the first name in the input. */
91 first = NULL;
93 cache_name = NULL;
94 /* Check the cache */
96 if (o->merge && o->pos < active_nr) {
97 /* This is a bit tricky: */
98 /* If the index has a subdirectory (with
99 * contents) as the first name, it'll get a
100 * filename like "foo/bar". But that's after
101 * "foo", so the entry in trees will get
102 * handled first, at which point we'll go into
103 * "foo", and deal with "bar" from the index,
104 * because the base will be "foo/". The only
105 * way we can actually have "foo/bar" first of
106 * all the things is if the trees don't
107 * contain "foo" at all, in which case we'll
108 * handle "foo/bar" without going into the
109 * directory, but that's fine (and will return
110 * an error anyway, with the added unknown
111 * file case.
112 */
113 cache_name = active_cache[o->pos]->name;
115 if (strlen(cache_name) > baselen &&
116 !memcmp(cache_name, base, baselen)) {
117 cache_name += baselen;
118 first = cache_name;
119 } else {
120 cache_name = NULL;
121 }
122 }
123#if DBRT_DEBUG > 1
125 if (first)
126 fprintf(stderr, "index %s\n", first);
127#endif
128 for (i = 0; i < len; i++) {
129 if (!posns[i] || posns[i] == df_conflict_list)
130 continue;
131#if DBRT_DEBUG > 1
132 fprintf(stderr, "%d %s\n", i + 1, posns[i]->name);
133#endif
134 if (!first || entcmp(first, firstdir,
135 posns[i]->name,
136 S_ISDIR(posns[i]->mode)) > 0) {
137 first = posns[i]->name;
138 firstdir = S_ISDIR(posns[i]->mode);
139 }
140 }
141 /* No name means we're done */
142 if (!first)
143 goto leave_directory;
144 pathlen = strlen(first);
146 ce_size = cache_entry_size(baselen + pathlen);
147 src = xcalloc(src_size, sizeof(struct cache_entry *));
149 subposns = xcalloc(len, sizeof(struct tree_list_entry *));
151 remove = -1;
153 if (cache_name && !strcmp(cache_name, first)) {
154 any_files = 1;
155 src[0] = active_cache[o->pos];
156 remove = o->pos;
157 if (o->skip_unmerged && ce_stage(src[0]))
158 skip_entry = 1;
159 }
160 for (i = 0; i < len; i++) {
162 struct cache_entry *ce;
163 if (!posns[i] ||
165 (posns[i] != df_conflict_list &&
166 strcmp(first, posns[i]->name))) {
167 continue;
168 }
169 if (posns[i] == df_conflict_list) {
171 src[i + o->merge] = o->df_conflict_entry;
172 continue;
173 }
174 if (S_ISDIR(posns[i]->mode)) {
176 struct tree *tree = lookup_tree(posns[i]->sha1);
177 struct tree_desc t;
178 any_dirs = 1;
179 parse_tree(tree);
180 init_tree_desc(&t, tree->buffer, tree->size);
181 subposns[i] = create_tree_entry_list(&t);
182 posns[i] = posns[i]->next;
183 src[i + o->merge] = o->df_conflict_entry;
184 continue;
185 }
186 if (skip_entry) {
188 subposns[i] = df_conflict_list;
189 posns[i] = posns[i]->next;
190 continue;
191 }
192 if (!o->merge)
194 ce_stage = 0;
195 else if (i + 1 < o->head_idx)
196 ce_stage = 1;
197 else if (i + 1 > o->head_idx)
198 ce_stage = 3;
199 else
200 ce_stage = 2;
201 ce = xcalloc(1, ce_size);
203 ce->ce_mode = create_ce_mode(posns[i]->mode);
204 ce->ce_flags = create_ce_flags(baselen + pathlen,
205 ce_stage);
206 memcpy(ce->name, base, baselen);
207 memcpy(ce->name + baselen, first, pathlen + 1);
208 any_files = 1;
210 hashcpy(ce->sha1, posns[i]->sha1);
212 src[i + o->merge] = ce;
213 subposns[i] = df_conflict_list;
214 posns[i] = posns[i]->next;
215 }
216 if (any_files) {
217 if (skip_entry) {
218 o->pos++;
219 while (o->pos < active_nr &&
220 !strcmp(active_cache[o->pos]->name,
221 src[0]->name))
222 o->pos++;
223 } else if (o->merge) {
224 int ret;
225#if DBRT_DEBUG > 1
227 fprintf(stderr, "%s:\n", first);
228 for (i = 0; i < src_size; i++) {
229 fprintf(stderr, " %d ", i);
230 if (src[i])
231 fprintf(stderr, "%06x %s\n", src[i]->ce_mode, sha1_to_hex(src[i]->sha1));
232 else
233 fprintf(stderr, "\n");
234 }
235#endif
236 ret = o->fn(src, o, remove);
237 if (ret < 0)
238 return ret;
239#if DBRT_DEBUG > 1
241 fprintf(stderr, "Added %d entries\n", ret);
242#endif
243 o->pos += ret;
244 } else {
245 remove_entry(remove);
246 for (i = 0; i < src_size; i++) {
247 if (src[i]) {
248 add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
249 }
250 }
251 }
252 }
253 if (any_dirs) {
254 char *newbase = xmalloc(baselen + 2 + pathlen);
255 memcpy(newbase, base, baselen);
256 memcpy(newbase + baselen, first, pathlen);
257 newbase[baselen + pathlen] = '/';
258 newbase[baselen + pathlen + 1] = '\0';
259 if (unpack_trees_rec(subposns, len, newbase, o,
260 df_conflict_list)) {
261 retval = -1;
262 goto leave_directory;
263 }
264 free(newbase);
265 }
266 free(subposns);
267 free(src);
268 } while (1);
269 leave_directory:
271 return retval;
272}
273/* Unlink the last component and attempt to remove leading
275 * directories, in case this unlink is the removal of the
276 * last entry in the directory -- empty directories are removed.
277 */
278static void unlink_entry(char *name, char *last_symlink)
279{
280 char *cp, *prev;
281 if (has_symlink_leading_path(name, last_symlink))
283 return;
284 if (unlink(name))
285 return;
286 prev = NULL;
287 while (1) {
288 int status;
289 cp = strrchr(name, '/');
290 if (prev)
291 *prev = '/';
292 if (!cp)
293 break;
294 *cp = 0;
296 status = rmdir(name);
297 if (status) {
298 *cp = '/';
299 break;
300 }
301 prev = cp;
302 }
303}
304static struct checkout state;
306static void check_updates(struct unpack_trees_options *o)
307{
308 unsigned cnt = 0, total = 0;
309 struct progress *progress = NULL;
310 char last_symlink[PATH_MAX];
311 int i;
312 if (o->update && o->verbose_update) {
314 for (total = cnt = 0; cnt < active_nr; cnt++) {
315 struct cache_entry *ce = active_cache[cnt];
316 if (ce->ce_flags & (CE_UPDATE | CE_REMOVE))
317 total++;
318 }
319 progress = start_progress_delay("Checking out files",
321 total, 50, 1);
322 cnt = 0;
323 }
324 *last_symlink = '\0';
326 for (i = 0; i < active_nr; i++) {
327 struct cache_entry *ce = active_cache[i];
328 if (ce->ce_flags & (CE_UPDATE | CE_REMOVE))
330 display_progress(progress, ++cnt);
331 if (ce->ce_flags & CE_REMOVE) {
332 if (o->update)
333 unlink_entry(ce->name, last_symlink);
334 remove_cache_entry_at(i);
335 i--;
336 continue;
337 }
338 if (ce->ce_flags & CE_UPDATE) {
339 ce->ce_flags &= ~CE_UPDATE;
340 if (o->update) {
341 checkout_entry(ce, &state, NULL);
342 *last_symlink = '\0';
343 }
344 }
345 }
346 stop_progress(&progress);
347}
348int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
350{
351 struct tree_entry_list **posns;
352 int i;
353 struct tree_entry_list df_conflict_list;
354 static struct cache_entry *dfc;
355 memset(&df_conflict_list, 0, sizeof(df_conflict_list));
357 df_conflict_list.next = &df_conflict_list;
358 memset(&state, 0, sizeof(state));
359 state.base_dir = "";
360 state.force = 1;
361 state.quiet = 1;
362 state.refresh_cache = 1;
363 o->merge_size = len;
365 if (!dfc)
367 dfc = xcalloc(1, sizeof(struct cache_entry) + 1);
368 o->df_conflict_entry = dfc;
369 if (len) {
371 posns = xmalloc(len * sizeof(struct tree_entry_list *));
372 for (i = 0; i < len; i++)
373 posns[i] = create_tree_entry_list(t+i);
374 if (unpack_trees_rec(posns, len, o->prefix ? o->prefix : "",
376 o, &df_conflict_list)) {
377 if (o->gently) {
378 discard_cache();
379 read_cache();
380 }
381 return -1;
382 }
383 }
384 if (o->trivial_merges_only && o->nontrivial_merge) {
386 if (o->gently) {
387 discard_cache();
388 read_cache();
389 }
390 return o->gently ? -1 :
391 error("Merge requires file-level merging");
392 }
393 check_updates(o);
395 return 0;
396}
397/* Here come the merge functions */
399static int reject_merge(struct cache_entry *ce)
401{
402 return error("Entry '%s' would be overwritten by merge. Cannot merge.",
403 ce->name);
404}
405static int same(struct cache_entry *a, struct cache_entry *b)
407{
408 if (!!a != !!b)
409 return 0;
410 if (!a && !b)
411 return 1;
412 return a->ce_mode == b->ce_mode &&
413 !hashcmp(a->sha1, b->sha1);
414}
415/*
418 * When a CE gets turned into an unmerged entry, we
419 * want it to be up-to-date
420 */
421static int verify_uptodate(struct cache_entry *ce,
422 struct unpack_trees_options *o)
423{
424 struct stat st;
425 if (o->index_only || o->reset)
427 return 0;
428 if (!lstat(ce->name, &st)) {
430 unsigned changed = ce_match_stat(ce, &st, CE_MATCH_IGNORE_VALID);
431 if (!changed)
432 return 0;
433 /*
434 * NEEDSWORK: the current default policy is to allow
435 * submodule to be out of sync wrt the supermodule
436 * index. This needs to be tightened later for
437 * submodules that are marked to be automatically
438 * checked out.
439 */
440 if (S_ISGITLINK(ce->ce_mode))
441 return 0;
442 errno = 0;
443 }
444 if (errno == ENOENT)
445 return 0;
446 return o->gently ? -1 :
447 error("Entry '%s' not uptodate. Cannot merge.", ce->name);
448}
449static void invalidate_ce_path(struct cache_entry *ce)
451{
452 if (ce)
453 cache_tree_invalidate_path(active_cache_tree, ce->name);
454}
455/*
457 * Check that checking out ce->sha1 in subdir ce->name is not
458 * going to overwrite any working files.
459 *
460 * Currently, git does not checkout subprojects during a superproject
461 * checkout, so it is not going to overwrite anything.
462 */
463static int verify_clean_submodule(struct cache_entry *ce, const char *action,
464 struct unpack_trees_options *o)
465{
466 return 0;
467}
468static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
470 struct unpack_trees_options *o)
471{
472 /*
473 * we are about to extract "ce->name"; we would not want to lose
474 * anything in the existing directory there.
475 */
476 int namelen;
477 int pos, i;
478 struct dir_struct d;
479 char *pathbuf;
480 int cnt = 0;
481 unsigned char sha1[20];
482 if (S_ISGITLINK(ce->ce_mode) &&
484 resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
485 /* If we are not going to update the submodule, then
486 * we don't care.
487 */
488 if (!hashcmp(sha1, ce->sha1))
489 return 0;
490 return verify_clean_submodule(ce, action, o);
491 }
492 /*
494 * First let's make sure we do not have a local modification
495 * in that directory.
496 */
497 namelen = strlen(ce->name);
498 pos = cache_name_pos(ce->name, namelen);
499 if (0 <= pos)
500 return cnt; /* we have it as nondirectory */
501 pos = -pos - 1;
502 for (i = pos; i < active_nr; i++) {
503 struct cache_entry *ce = active_cache[i];
504 int len = ce_namelen(ce);
505 if (len < namelen ||
506 strncmp(ce->name, ce->name, namelen) ||
507 ce->name[namelen] != '/')
508 break;
509 /*
510 * ce->name is an entry in the subdirectory.
511 */
512 if (!ce_stage(ce)) {
513 if (verify_uptodate(ce, o))
514 return -1;
515 ce->ce_flags |= CE_REMOVE;
516 }
517 cnt++;
518 }
519 /*
521 * Then we need to make sure that we do not lose a locally
522 * present file that is not ignored.
523 */
524 pathbuf = xmalloc(namelen + 2);
525 memcpy(pathbuf, ce->name, namelen);
526 strcpy(pathbuf+namelen, "/");
527 memset(&d, 0, sizeof(d));
529 if (o->dir)
530 d.exclude_per_dir = o->dir->exclude_per_dir;
531 i = read_directory(&d, ce->name, pathbuf, namelen+1, NULL);
532 if (i)
533 return o->gently ? -1 :
534 error("Updating '%s' would lose untracked files in it",
535 ce->name);
536 free(pathbuf);
537 return cnt;
538}
539/*
541 * We do not want to remove or overwrite a working tree file that
542 * is not tracked, unless it is ignored.
543 */
544static int verify_absent(struct cache_entry *ce, const char *action,
545 struct unpack_trees_options *o)
546{
547 struct stat st;
548 if (o->index_only || o->reset || !o->update)
550 return 0;
551 if (has_symlink_leading_path(ce->name, NULL))
553 return 0;
554 if (!lstat(ce->name, &st)) {
556 int cnt;
557 int dtype = ce_to_dtype(ce);
558 if (o->dir && excluded(o->dir, ce->name, &dtype))
560 /*
561 * ce->name is explicitly excluded, so it is Ok to
562 * overwrite it.
563 */
564 return 0;
565 if (S_ISDIR(st.st_mode)) {
566 /*
567 * We are checking out path "foo" and
568 * found "foo/." in the working tree.
569 * This is tricky -- if we have modified
570 * files that are in "foo/" we would lose
571 * it.
572 */
573 cnt = verify_clean_subdirectory(ce, action, o);
574 /*
576 * If this removed entries from the index,
577 * what that means is:
578 *
579 * (1) the caller unpack_trees_rec() saw path/foo
580 * in the index, and it has not removed it because
581 * it thinks it is handling 'path' as blob with
582 * D/F conflict;
583 * (2) we will return "ok, we placed a merged entry
584 * in the index" which would cause o->pos to be
585 * incremented by one;
586 * (3) however, original o->pos now has 'path/foo'
587 * marked with "to be removed".
588 *
589 * We need to increment it by the number of
590 * deleted entries here.
591 */
592 o->pos += cnt;
593 return 0;
594 }
595 /*
597 * The previous round may already have decided to
598 * delete this path, which is in a subdirectory that
599 * is being replaced with a blob.
600 */
601 cnt = cache_name_pos(ce->name, strlen(ce->name));
602 if (0 <= cnt) {
603 struct cache_entry *ce = active_cache[cnt];
604 if (ce->ce_flags & CE_REMOVE)
605 return 0;
606 }
607 return o->gently ? -1 :
609 error("Untracked working tree file '%s' "
610 "would be %s by merge.", ce->name, action);
611 }
612 return 0;
613}
614static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
616 struct unpack_trees_options *o)
617{
618 merge->ce_flags |= CE_UPDATE;
619 if (old) {
620 /*
621 * See if we can re-use the old CE directly?
622 * That way we get the uptodate stat info.
623 *
624 * This also removes the UPDATE flag on
625 * a match.
626 */
627 if (same(old, merge)) {
628 copy_cache_entry(merge, old);
629 } else {
630 if (verify_uptodate(old, o))
631 return -1;
632 invalidate_ce_path(old);
633 }
634 }
635 else {
636 if (verify_absent(merge, "overwritten", o))
637 return -1;
638 invalidate_ce_path(merge);
639 }
640 merge->ce_flags &= ~CE_STAGEMASK;
642 add_cache_entry(merge, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
643 return 1;
644}
645static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
647 struct unpack_trees_options *o)
648{
649 if (old) {
650 if (verify_uptodate(old, o))
651 return -1;
652 } else
653 if (verify_absent(ce, "removed", o))
654 return -1;
655 ce->ce_flags |= CE_REMOVE;
656 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
657 invalidate_ce_path(ce);
658 return 1;
659}
660static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
662{
663 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
664 return 1;
665}
666#if DBRT_DEBUG
668static void show_stage_entry(FILE *o,
669 const char *label, const struct cache_entry *ce)
670{
671 if (!ce)
672 fprintf(o, "%s (missing)\n", label);
673 else
674 fprintf(o, "%s%06o %s %d\t%s\n",
675 label,
676 ce->ce_mode,
677 sha1_to_hex(ce->sha1),
678 ce_stage(ce),
679 ce->name);
680}
681#endif
682int threeway_merge(struct cache_entry **stages,
684 struct unpack_trees_options *o,
685 int remove)
686{
687 struct cache_entry *index;
688 struct cache_entry *head;
689 struct cache_entry *remote = stages[o->head_idx + 1];
690 int count;
691 int head_match = 0;
692 int remote_match = 0;
693 int df_conflict_head = 0;
695 int df_conflict_remote = 0;
696 int any_anc_missing = 0;
698 int no_anc_exists = 1;
699 int i;
700 for (i = 1; i < o->head_idx; i++) {
702 if (!stages[i] || stages[i] == o->df_conflict_entry)
703 any_anc_missing = 1;
704 else
705 no_anc_exists = 0;
706 }
707 index = stages[0];
709 head = stages[o->head_idx];
710 if (head == o->df_conflict_entry) {
712 df_conflict_head = 1;
713 head = NULL;
714 }
715 if (remote == o->df_conflict_entry) {
717 df_conflict_remote = 1;
718 remote = NULL;
719 }
720 /* First, if there's a #16 situation, note that to prevent #13
722 * and #14.
723 */
724 if (!same(remote, head)) {
725 for (i = 1; i < o->head_idx; i++) {
726 if (same(stages[i], head)) {
727 head_match = i;
728 }
729 if (same(stages[i], remote)) {
730 remote_match = i;
731 }
732 }
733 }
734 /* We start with cases where the index is allowed to match
736 * something other than the head: #14(ALT) and #2ALT, where it
737 * is permitted to match the result instead.
738 */
739 /* #14, #14ALT, #2ALT */
740 if (remote && !df_conflict_head && head_match && !remote_match) {
741 if (index && !same(index, remote) && !same(index, head))
742 return o->gently ? -1 : reject_merge(index);
743 return merged_entry(remote, index, o);
744 }
745 /*
746 * If we have an entry in the index cache, then we want to
747 * make sure that it matches head.
748 */
749 if (index && !same(index, head))
750 return o->gently ? -1 : reject_merge(index);
751 if (head) {
753 /* #5ALT, #15 */
754 if (same(head, remote))
755 return merged_entry(head, index, o);
756 /* #13, #3ALT */
757 if (!df_conflict_remote && remote_match && !head_match)
758 return merged_entry(head, index, o);
759 }
760 /* #1 */
762 if (!head && !remote && any_anc_missing) {
763 remove_entry(remove);
764 return 0;
765 }
766 /* Under the new "aggressive" rule, we resolve mostly trivial
768 * cases that we historically had git-merge-one-file resolve.
769 */
770 if (o->aggressive) {
771 int head_deleted = !head && !df_conflict_head;
772 int remote_deleted = !remote && !df_conflict_remote;
773 struct cache_entry *ce = NULL;
774 if (index)
776 ce = index;
777 else if (head)
778 ce = head;
779 else if (remote)
780 ce = remote;
781 else {
782 for (i = 1; i < o->head_idx; i++) {
783 if (stages[i] && stages[i] != o->df_conflict_entry) {
784 ce = stages[i];
785 break;
786 }
787 }
788 }
789 /*
791 * Deleted in both.
792 * Deleted in one and unchanged in the other.
793 */
794 if ((head_deleted && remote_deleted) ||
795 (head_deleted && remote && remote_match) ||
796 (remote_deleted && head && head_match)) {
797 remove_entry(remove);
798 if (index)
799 return deleted_entry(index, index, o);
800 else if (ce && !head_deleted) {
801 if (verify_absent(ce, "removed", o))
802 return -1;
803 }
804 return 0;
805 }
806 /*
807 * Added in both, identically.
808 */
809 if (no_anc_exists && head && remote && same(head, remote))
810 return merged_entry(head, index, o);
811 }
813 /* Below are "no merge" cases, which require that the index be
815 * up-to-date to avoid the files getting overwritten with
816 * conflict resolution files.
817 */
818 if (index) {
819 if (verify_uptodate(index, o))
820 return -1;
821 }
822 remove_entry(remove);
824 o->nontrivial_merge = 1;
825 /* #2, #3, #4, #6, #7, #9, #10, #11. */
827 count = 0;
828 if (!head_match || !remote_match) {
829 for (i = 1; i < o->head_idx; i++) {
830 if (stages[i] && stages[i] != o->df_conflict_entry) {
831 keep_entry(stages[i], o);
832 count++;
833 break;
834 }
835 }
836 }
837#if DBRT_DEBUG
838 else {
839 fprintf(stderr, "read-tree: warning #16 detected\n");
840 show_stage_entry(stderr, "head ", stages[head_match]);
841 show_stage_entry(stderr, "remote ", stages[remote_match]);
842 }
843#endif
844 if (head) { count += keep_entry(head, o); }
845 if (remote) { count += keep_entry(remote, o); }
846 return count;
847}
848/*
850 * Two-way merge.
851 *
852 * The rule is to "carry forward" what is in the index without losing
853 * information across a "fast forward", favoring a successful merge
854 * over a merge failure when it makes sense. For details of the
855 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
856 *
857 */
858int twoway_merge(struct cache_entry **src,
859 struct unpack_trees_options *o,
860 int remove)
861{
862 struct cache_entry *current = src[0];
863 struct cache_entry *oldtree = src[1];
864 struct cache_entry *newtree = src[2];
865 if (o->merge_size != 2)
867 return error("Cannot do a twoway merge of %d trees",
868 o->merge_size);
869 if (oldtree == o->df_conflict_entry)
871 oldtree = NULL;
872 if (newtree == o->df_conflict_entry)
873 newtree = NULL;
874 if (current) {
876 if ((!oldtree && !newtree) || /* 4 and 5 */
877 (!oldtree && newtree &&
878 same(current, newtree)) || /* 6 and 7 */
879 (oldtree && newtree &&
880 same(oldtree, newtree)) || /* 14 and 15 */
881 (oldtree && newtree &&
882 !same(oldtree, newtree) && /* 18 and 19 */
883 same(current, newtree))) {
884 return keep_entry(current, o);
885 }
886 else if (oldtree && !newtree && same(current, oldtree)) {
887 /* 10 or 11 */
888 remove_entry(remove);
889 return deleted_entry(oldtree, current, o);
890 }
891 else if (oldtree && newtree &&
892 same(current, oldtree) && !same(current, newtree)) {
893 /* 20 or 21 */
894 return merged_entry(newtree, current, o);
895 }
896 else {
897 /* all other failures */
898 remove_entry(remove);
899 if (oldtree)
900 return o->gently ? -1 : reject_merge(oldtree);
901 if (current)
902 return o->gently ? -1 : reject_merge(current);
903 if (newtree)
904 return o->gently ? -1 : reject_merge(newtree);
905 return -1;
906 }
907 }
908 else if (newtree)
909 return merged_entry(newtree, current, o);
910 remove_entry(remove);
911 return deleted_entry(oldtree, current, o);
912}
913/*
915 * Bind merge.
916 *
917 * Keep the index entries at stage0, collapse stage1 but make sure
918 * stage0 does not have anything there.
919 */
920int bind_merge(struct cache_entry **src,
921 struct unpack_trees_options *o,
922 int remove)
923{
924 struct cache_entry *old = src[0];
925 struct cache_entry *a = src[1];
926 if (o->merge_size != 1)
928 return error("Cannot do a bind merge of %d trees\n",
929 o->merge_size);
930 if (a && old)
931 return o->gently ? -1 :
932 error("Entry '%s' overlaps. Cannot bind.", a->name);
933 if (!a)
934 return keep_entry(old, o);
935 else
936 return merged_entry(a, NULL, o);
937}
938/*
940 * One-way merge.
941 *
942 * The rule is:
943 * - take the stat information from stage0, take the data from stage1
944 */
945int oneway_merge(struct cache_entry **src,
946 struct unpack_trees_options *o,
947 int remove)
948{
949 struct cache_entry *old = src[0];
950 struct cache_entry *a = src[1];
951 if (o->merge_size != 1)
953 return error("Cannot do a oneway merge of %d trees",
954 o->merge_size);
955 if (!a) {
957 remove_entry(remove);
958 return deleted_entry(old, old, o);
959 }
960 if (old && same(old, a)) {
961 if (o->reset) {
962 struct stat st;
963 if (lstat(old->name, &st) ||
964 ce_match_stat(old, &st, CE_MATCH_IGNORE_VALID))
965 old->ce_flags |= CE_UPDATE;
966 }
967 return keep_entry(old, o);
968 }
969 return merged_entry(a, old, o);
970}