1/*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 */
6#define DBRT_DEBUG 1
7#include "cache.h"
9#include "object.h"
11#include "tree.h"
12#include "tree-walk.h"
13#include "cache-tree.h"
14#include <sys/time.h>
15#include <signal.h>
16#include "builtin.h"
17static int reset = 0;
19static int merge = 0;
20static int update = 0;
21static int index_only = 0;
22static int nontrivial_merge = 0;
23static int trivial_merges_only = 0;
24static int aggressive = 0;
25static int verbose_update = 0;
26static volatile int progress_update = 0;
27static int head_idx = -1;
29static int merge_size = 0;
30static struct object_list *trees = NULL;
32static struct cache_entry df_conflict_entry = {
34};
35struct tree_entry_list {
37 struct tree_entry_list *next;
38 unsigned directory : 1;
39 unsigned executable : 1;
40 unsigned symlink : 1;
41 unsigned int mode;
42 const char *name;
43 const unsigned char *sha1;
44};
45static struct tree_entry_list df_conflict_list = {
47 .name = NULL,
48 .next = &df_conflict_list
49};
50typedef int (*merge_fn_t)(struct cache_entry **src);
52static struct tree_entry_list *create_tree_entry_list(struct tree *tree)
54{
55 struct tree_desc desc;
56 struct name_entry one;
57 struct tree_entry_list *ret = NULL;
58 struct tree_entry_list **list_p = &ret;
59 desc.buf = tree->buffer;
61 desc.size = tree->size;
62 while (tree_entry(&desc, &one)) {
64 struct tree_entry_list *entry;
65 entry = xmalloc(sizeof(struct tree_entry_list));
67 entry->name = one.path;
68 entry->sha1 = one.sha1;
69 entry->mode = one.mode;
70 entry->directory = S_ISDIR(one.mode) != 0;
71 entry->executable = (one.mode & S_IXUSR) != 0;
72 entry->symlink = S_ISLNK(one.mode) != 0;
73 entry->next = NULL;
74 *list_p = entry;
76 list_p = &entry->next;
77 }
78 return ret;
79}
80static int entcmp(const char *name1, int dir1, const char *name2, int dir2)
82{
83 int len1 = strlen(name1);
84 int len2 = strlen(name2);
85 int len = len1 < len2 ? len1 : len2;
86 int ret = memcmp(name1, name2, len);
87 unsigned char c1, c2;
88 if (ret)
89 return ret;
90 c1 = name1[len];
91 c2 = name2[len];
92 if (!c1 && dir1)
93 c1 = '/';
94 if (!c2 && dir2)
95 c2 = '/';
96 ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
97 if (c1 && c2 && !ret)
98 ret = len1 - len2;
99 return ret;
100}
101static int unpack_trees_rec(struct tree_entry_list **posns, int len,
103 const char *base, merge_fn_t fn, int *indpos)
104{
105 int baselen = strlen(base);
106 int src_size = len + 1;
107 do {
108 int i;
109 const char *first;
110 int firstdir = 0;
111 int pathlen;
112 unsigned ce_size;
113 struct tree_entry_list **subposns;
114 struct cache_entry **src;
115 int any_files = 0;
116 int any_dirs = 0;
117 char *cache_name;
118 int ce_stage;
119 /* Find the first name in the input. */
121 first = NULL;
123 cache_name = NULL;
124 /* Check the cache */
126 if (merge && *indpos < active_nr) {
127 /* This is a bit tricky: */
128 /* If the index has a subdirectory (with
129 * contents) as the first name, it'll get a
130 * filename like "foo/bar". But that's after
131 * "foo", so the entry in trees will get
132 * handled first, at which point we'll go into
133 * "foo", and deal with "bar" from the index,
134 * because the base will be "foo/". The only
135 * way we can actually have "foo/bar" first of
136 * all the things is if the trees don't
137 * contain "foo" at all, in which case we'll
138 * handle "foo/bar" without going into the
139 * directory, but that's fine (and will return
140 * an error anyway, with the added unknown
141 * file case.
142 */
143 cache_name = active_cache[*indpos]->name;
145 if (strlen(cache_name) > baselen &&
146 !memcmp(cache_name, base, baselen)) {
147 cache_name += baselen;
148 first = cache_name;
149 } else {
150 cache_name = NULL;
151 }
152 }
153#if DBRT_DEBUG > 1
155 if (first)
156 printf("index %s\n", first);
157#endif
158 for (i = 0; i < len; i++) {
159 if (!posns[i] || posns[i] == &df_conflict_list)
160 continue;
161#if DBRT_DEBUG > 1
162 printf("%d %s\n", i + 1, posns[i]->name);
163#endif
164 if (!first || entcmp(first, firstdir,
165 posns[i]->name,
166 posns[i]->directory) > 0) {
167 first = posns[i]->name;
168 firstdir = posns[i]->directory;
169 }
170 }
171 /* No name means we're done */
172 if (!first)
173 return 0;
174 pathlen = strlen(first);
176 ce_size = cache_entry_size(baselen + pathlen);
177 src = xcalloc(src_size, sizeof(struct cache_entry *));
179 subposns = xcalloc(len, sizeof(struct tree_list_entry *));
181 if (cache_name && !strcmp(cache_name, first)) {
183 any_files = 1;
184 src[0] = active_cache[*indpos];
185 remove_cache_entry_at(*indpos);
186 }
187 for (i = 0; i < len; i++) {
189 struct cache_entry *ce;
190 if (!posns[i] ||
192 (posns[i] != &df_conflict_list &&
193 strcmp(first, posns[i]->name))) {
194 continue;
195 }
196 if (posns[i] == &df_conflict_list) {
198 src[i + merge] = &df_conflict_entry;
199 continue;
200 }
201 if (posns[i]->directory) {
203 struct tree *tree = lookup_tree(posns[i]->sha1);
204 any_dirs = 1;
205 parse_tree(tree);
206 subposns[i] = create_tree_entry_list(tree);
207 posns[i] = posns[i]->next;
208 src[i + merge] = &df_conflict_entry;
209 continue;
210 }
211 if (!merge)
213 ce_stage = 0;
214 else if (i + 1 < head_idx)
215 ce_stage = 1;
216 else if (i + 1 > head_idx)
217 ce_stage = 3;
218 else
219 ce_stage = 2;
220 ce = xcalloc(1, ce_size);
222 ce->ce_mode = create_ce_mode(posns[i]->mode);
223 ce->ce_flags = create_ce_flags(baselen + pathlen,
224 ce_stage);
225 memcpy(ce->name, base, baselen);
226 memcpy(ce->name + baselen, first, pathlen + 1);
227 any_files = 1;
229 memcpy(ce->sha1, posns[i]->sha1, 20);
231 src[i + merge] = ce;
232 subposns[i] = &df_conflict_list;
233 posns[i] = posns[i]->next;
234 }
235 if (any_files) {
236 if (merge) {
237 int ret;
238#if DBRT_DEBUG > 1
240 printf("%s:\n", first);
241 for (i = 0; i < src_size; i++) {
242 printf(" %d ", i);
243 if (src[i])
244 printf("%s\n", sha1_to_hex(src[i]->sha1));
245 else
246 printf("\n");
247 }
248#endif
249 ret = fn(src);
250
251#if DBRT_DEBUG > 1
252 printf("Added %d entries\n", ret);
253#endif
254 *indpos += ret;
255 } else {
256 for (i = 0; i < src_size; i++) {
257 if (src[i]) {
258 add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
259 }
260 }
261 }
262 }
263 if (any_dirs) {
264 char *newbase = xmalloc(baselen + 2 + pathlen);
265 memcpy(newbase, base, baselen);
266 memcpy(newbase + baselen, first, pathlen);
267 newbase[baselen + pathlen] = '/';
268 newbase[baselen + pathlen + 1] = '\0';
269 if (unpack_trees_rec(subposns, len, newbase, fn,
270 indpos))
271 return -1;
272 free(newbase);
273 }
274 free(subposns);
275 free(src);
276 } while (1);
277}
278static void reject_merge(struct cache_entry *ce)
280{
281 die("Entry '%s' would be overwritten by merge. Cannot merge.",
282 ce->name);
283}
284/* Unlink the last component and attempt to remove leading
286 * directories, in case this unlink is the removal of the
287 * last entry in the directory -- empty directories are removed.
288 */
289static void unlink_entry(char *name)
290{
291 char *cp, *prev;
292 if (unlink(name))
294 return;
295 prev = NULL;
296 while (1) {
297 int status;
298 cp = strrchr(name, '/');
299 if (prev)
300 *prev = '/';
301 if (!cp)
302 break;
303 *cp = 0;
305 status = rmdir(name);
306 if (status) {
307 *cp = '/';
308 break;
309 }
310 prev = cp;
311 }
312}
313static void progress_interval(int signum)
315{
316 progress_update = 1;
317}
318static void setup_progress_signal(void)
320{
321 struct sigaction sa;
322 struct itimerval v;
323 memset(&sa, 0, sizeof(sa));
325 sa.sa_handler = progress_interval;
326 sigemptyset(&sa.sa_mask);
327 sa.sa_flags = SA_RESTART;
328 sigaction(SIGALRM, &sa, NULL);
329 v.it_interval.tv_sec = 1;
331 v.it_interval.tv_usec = 0;
332 v.it_value = v.it_interval;
333 setitimer(ITIMER_REAL, &v, NULL);
334}
335static void check_updates(struct cache_entry **src, int nr)
337{
338 static struct checkout state = {
339 .base_dir = "",
340 .force = 1,
341 .quiet = 1,
342 .refresh_cache = 1,
343 };
344 unsigned short mask = htons(CE_UPDATE);
345 unsigned last_percent = 200, cnt = 0, total = 0;
346 if (update && verbose_update) {
348 for (total = cnt = 0; cnt < nr; cnt++) {
349 struct cache_entry *ce = src[cnt];
350 if (!ce->ce_mode || ce->ce_flags & mask)
351 total++;
352 }
353 /* Don't bother doing this for very small updates */
355 if (total < 250)
356 total = 0;
357 if (total) {
359 fprintf(stderr, "Checking files out...\n");
360 setup_progress_signal();
361 progress_update = 1;
362 }
363 cnt = 0;
364 }
365 while (nr--) {
367 struct cache_entry *ce = *src++;
368 if (total) {
370 if (!ce->ce_mode || ce->ce_flags & mask) {
371 unsigned percent;
372 cnt++;
373 percent = (cnt * 100) / total;
374 if (percent != last_percent ||
375 progress_update) {
376 fprintf(stderr, "%4u%% (%u/%u) done\r",
377 percent, cnt, total);
378 last_percent = percent;
379 }
380 }
381 }
382 if (!ce->ce_mode) {
383 if (update)
384 unlink_entry(ce->name);
385 continue;
386 }
387 if (ce->ce_flags & mask) {
388 ce->ce_flags &= ~mask;
389 if (update)
390 checkout_entry(ce, &state, NULL);
391 }
392 }
393 if (total) {
394 signal(SIGALRM, SIG_IGN);
395 fputc('\n', stderr);
396 }
397}
398static int unpack_trees(merge_fn_t fn)
400{
401 int indpos = 0;
402 unsigned len = object_list_length(trees);
403 struct tree_entry_list **posns;
404 int i;
405 struct object_list *posn = trees;
406 merge_size = len;
407 if (len) {
409 posns = xmalloc(len * sizeof(struct tree_entry_list *));
410 for (i = 0; i < len; i++) {
411 posns[i] = create_tree_entry_list((struct tree *) posn->item);
412 posn = posn->next;
413 }
414 if (unpack_trees_rec(posns, len, "", fn, &indpos))
415 return -1;
416 }
417 if (trivial_merges_only && nontrivial_merge)
419 die("Merge requires file-level merging");
420 check_updates(active_cache, active_nr);
422 return 0;
423}
424static int list_tree(unsigned char *sha1)
426{
427 struct tree *tree = parse_tree_indirect(sha1);
428 if (!tree)
429 return -1;
430 object_list_append(&tree->object, &trees);
431 return 0;
432}
433static int same(struct cache_entry *a, struct cache_entry *b)
435{
436 if (!!a != !!b)
437 return 0;
438 if (!a && !b)
439 return 1;
440 return a->ce_mode == b->ce_mode &&
441 !memcmp(a->sha1, b->sha1, 20);
442}
443/*
446 * When a CE gets turned into an unmerged entry, we
447 * want it to be up-to-date
448 */
449static void verify_uptodate(struct cache_entry *ce)
450{
451 struct stat st;
452 if (index_only || reset)
454 return;
455 if (!lstat(ce->name, &st)) {
457 unsigned changed = ce_match_stat(ce, &st, 1);
458 if (!changed)
459 return;
460 errno = 0;
461 }
462 if (reset) {
463 ce->ce_flags |= htons(CE_UPDATE);
464 return;
465 }
466 if (errno == ENOENT)
467 return;
468 die("Entry '%s' not uptodate. Cannot merge.", ce->name);
469}
470static void invalidate_ce_path(struct cache_entry *ce)
472{
473 if (ce)
474 cache_tree_invalidate_path(active_cache_tree, ce->name);
475}
476/*
478 * We do not want to remove or overwrite a working tree file that
479 * is not tracked.
480 */
481static void verify_absent(const char *path, const char *action)
482{
483 struct stat st;
484 if (index_only || reset || !update)
486 return;
487 if (!lstat(path, &st))
488 die("Untracked working tree file '%s' "
489 "would be %s by merge.", path, action);
490}
491static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
493{
494 merge->ce_flags |= htons(CE_UPDATE);
495 if (old) {
496 /*
497 * See if we can re-use the old CE directly?
498 * That way we get the uptodate stat info.
499 *
500 * This also removes the UPDATE flag on
501 * a match.
502 */
503 if (same(old, merge)) {
504 *merge = *old;
505 } else {
506 verify_uptodate(old);
507 invalidate_ce_path(old);
508 }
509 }
510 else {
511 verify_absent(merge->name, "overwritten");
512 invalidate_ce_path(merge);
513 }
514 merge->ce_flags &= ~htons(CE_STAGEMASK);
516 add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
517 return 1;
518}
519static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
521{
522 if (old)
523 verify_uptodate(old);
524 else
525 verify_absent(ce->name, "removed");
526 ce->ce_mode = 0;
527 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
528 invalidate_ce_path(ce);
529 return 1;
530}
531static int keep_entry(struct cache_entry *ce)
533{
534 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
535 return 1;
536}
537#if DBRT_DEBUG
539static void show_stage_entry(FILE *o,
540 const char *label, const struct cache_entry *ce)
541{
542 if (!ce)
543 fprintf(o, "%s (missing)\n", label);
544 else
545 fprintf(o, "%s%06o %s %d\t%s\n",
546 label,
547 ntohl(ce->ce_mode),
548 sha1_to_hex(ce->sha1),
549 ce_stage(ce),
550 ce->name);
551}
552#endif
553static int threeway_merge(struct cache_entry **stages)
555{
556 struct cache_entry *index;
557 struct cache_entry *head;
558 struct cache_entry *remote = stages[head_idx + 1];
559 int count;
560 int head_match = 0;
561 int remote_match = 0;
562 const char *path = NULL;
563 int df_conflict_head = 0;
565 int df_conflict_remote = 0;
566 int any_anc_missing = 0;
568 int no_anc_exists = 1;
569 int i;
570 for (i = 1; i < head_idx; i++) {
572 if (!stages[i])
573 any_anc_missing = 1;
574 else {
575 if (!path)
576 path = stages[i]->name;
577 no_anc_exists = 0;
578 }
579 }
580 index = stages[0];
582 head = stages[head_idx];
583 if (head == &df_conflict_entry) {
585 df_conflict_head = 1;
586 head = NULL;
587 }
588 if (remote == &df_conflict_entry) {
590 df_conflict_remote = 1;
591 remote = NULL;
592 }
593 if (!path && index)
595 path = index->name;
596 if (!path && head)
597 path = head->name;
598 if (!path && remote)
599 path = remote->name;
600 /* First, if there's a #16 situation, note that to prevent #13
602 * and #14.
603 */
604 if (!same(remote, head)) {
605 for (i = 1; i < head_idx; i++) {
606 if (same(stages[i], head)) {
607 head_match = i;
608 }
609 if (same(stages[i], remote)) {
610 remote_match = i;
611 }
612 }
613 }
614 /* We start with cases where the index is allowed to match
616 * something other than the head: #14(ALT) and #2ALT, where it
617 * is permitted to match the result instead.
618 */
619 /* #14, #14ALT, #2ALT */
620 if (remote && !df_conflict_head && head_match && !remote_match) {
621 if (index && !same(index, remote) && !same(index, head))
622 reject_merge(index);
623 return merged_entry(remote, index);
624 }
625 /*
626 * If we have an entry in the index cache, then we want to
627 * make sure that it matches head.
628 */
629 if (index && !same(index, head)) {
630 reject_merge(index);
631 }
632 if (head) {
634 /* #5ALT, #15 */
635 if (same(head, remote))
636 return merged_entry(head, index);
637 /* #13, #3ALT */
638 if (!df_conflict_remote && remote_match && !head_match)
639 return merged_entry(head, index);
640 }
641 /* #1 */
643 if (!head && !remote && any_anc_missing)
644 return 0;
645 /* Under the new "aggressive" rule, we resolve mostly trivial
647 * cases that we historically had git-merge-one-file resolve.
648 */
649 if (aggressive) {
650 int head_deleted = !head && !df_conflict_head;
651 int remote_deleted = !remote && !df_conflict_remote;
652 /*
653 * Deleted in both.
654 * Deleted in one and unchanged in the other.
655 */
656 if ((head_deleted && remote_deleted) ||
657 (head_deleted && remote && remote_match) ||
658 (remote_deleted && head && head_match)) {
659 if (index)
660 return deleted_entry(index, index);
661 else if (path)
662 verify_absent(path, "removed");
663 return 0;
664 }
665 /*
666 * Added in both, identically.
667 */
668 if (no_anc_exists && head && remote && same(head, remote))
669 return merged_entry(head, index);
670 }
672 /* Below are "no merge" cases, which require that the index be
674 * up-to-date to avoid the files getting overwritten with
675 * conflict resolution files.
676 */
677 if (index) {
678 verify_uptodate(index);
679 }
680 else if (path)
681 verify_absent(path, "overwritten");
682 nontrivial_merge = 1;
684 /* #2, #3, #4, #6, #7, #9, #11. */
686 count = 0;
687 if (!head_match || !remote_match) {
688 for (i = 1; i < head_idx; i++) {
689 if (stages[i]) {
690 keep_entry(stages[i]);
691 count++;
692 break;
693 }
694 }
695 }
696#if DBRT_DEBUG
697 else {
698 fprintf(stderr, "read-tree: warning #16 detected\n");
699 show_stage_entry(stderr, "head ", stages[head_match]);
700 show_stage_entry(stderr, "remote ", stages[remote_match]);
701 }
702#endif
703 if (head) { count += keep_entry(head); }
704 if (remote) { count += keep_entry(remote); }
705 return count;
706}
707/*
709 * Two-way merge.
710 *
711 * The rule is to "carry forward" what is in the index without losing
712 * information across a "fast forward", favoring a successful merge
713 * over a merge failure when it makes sense. For details of the
714 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
715 *
716 */
717static int twoway_merge(struct cache_entry **src)
718{
719 struct cache_entry *current = src[0];
720 struct cache_entry *oldtree = src[1], *newtree = src[2];
721 if (merge_size != 2)
723 return error("Cannot do a twoway merge of %d trees",
724 merge_size);
725 if (current) {
727 if ((!oldtree && !newtree) || /* 4 and 5 */
728 (!oldtree && newtree &&
729 same(current, newtree)) || /* 6 and 7 */
730 (oldtree && newtree &&
731 same(oldtree, newtree)) || /* 14 and 15 */
732 (oldtree && newtree &&
733 !same(oldtree, newtree) && /* 18 and 19*/
734 same(current, newtree))) {
735 return keep_entry(current);
736 }
737 else if (oldtree && !newtree && same(current, oldtree)) {
738 /* 10 or 11 */
739 return deleted_entry(oldtree, current);
740 }
741 else if (oldtree && newtree &&
742 same(current, oldtree) && !same(current, newtree)) {
743 /* 20 or 21 */
744 return merged_entry(newtree, current);
745 }
746 else {
747 /* all other failures */
748 if (oldtree)
749 reject_merge(oldtree);
750 if (current)
751 reject_merge(current);
752 if (newtree)
753 reject_merge(newtree);
754 return -1;
755 }
756 }
757 else if (newtree)
758 return merged_entry(newtree, current);
759 else
760 return deleted_entry(oldtree, current);
761}
762/*
764 * One-way merge.
765 *
766 * The rule is:
767 * - take the stat information from stage0, take the data from stage1
768 */
769static int oneway_merge(struct cache_entry **src)
770{
771 struct cache_entry *old = src[0];
772 struct cache_entry *a = src[1];
773 if (merge_size != 1)
775 return error("Cannot do a oneway merge of %d trees",
776 merge_size);
777 if (!a)
779 return deleted_entry(old, old);
780 if (old && same(old, a)) {
781 if (reset) {
782 struct stat st;
783 if (lstat(old->name, &st) ||
784 ce_match_stat(old, &st, 1))
785 old->ce_flags |= htons(CE_UPDATE);
786 }
787 return keep_entry(old);
788 }
789 return merged_entry(a, old);
790}
791static int read_cache_unmerged(void)
793{
794 int i;
795 struct cache_entry **dst;
796 struct cache_entry *last = NULL;
797 read_cache();
799 dst = active_cache;
800 for (i = 0; i < active_nr; i++) {
801 struct cache_entry *ce = active_cache[i];
802 if (ce_stage(ce)) {
803 if (last && !strcmp(ce->name, last->name))
804 continue;
805 invalidate_ce_path(ce);
806 last = ce;
807 ce->ce_mode = 0;
808 ce->ce_flags &= ~htons(CE_STAGEMASK);
809 }
810 *dst++ = ce;
811 }
812 active_nr = dst - active_cache;
813 return !!last;
814}
815static void prime_cache_tree_rec(struct cache_tree *it, struct tree *tree)
817{
818 struct tree_desc desc;
819 struct name_entry entry;
820 int cnt;
821 memcpy(it->sha1, tree->object.sha1, 20);
823 desc.buf = tree->buffer;
824 desc.size = tree->size;
825 cnt = 0;
826 while (tree_entry(&desc, &entry)) {
827 if (!S_ISDIR(entry.mode))
828 cnt++;
829 else {
830 struct cache_tree_sub *sub;
831 struct tree *subtree = lookup_tree(entry.sha1);
832 if (!subtree->object.parsed)
833 parse_tree(subtree);
834 sub = cache_tree_sub(it, entry.path);
835 sub->cache_tree = cache_tree();
836 prime_cache_tree_rec(sub->cache_tree, subtree);
837 cnt += sub->cache_tree->entry_count;
838 }
839 }
840 it->entry_count = cnt;
841}
842static void prime_cache_tree(void)
844{
845 struct tree *tree = (struct tree *)trees->item;
846 if (!tree)
847 return;
848 active_cache_tree = cache_tree();
849 prime_cache_tree_rec(active_cache_tree, tree);
850}
852static const char read_tree_usage[] = "git-read-tree (<sha> | -m [--aggressive] [-u | -i] <sha1> [<sha2> [<sha3>]])";
854static struct cache_file cache_file;
856int cmd_read_tree(int argc, const char **argv, char **envp)
858{
859 int i, newfd, stage = 0;
860 unsigned char sha1[20];
861 merge_fn_t fn = NULL;
862 setup_git_directory();
864 git_config(git_default_config);
865 newfd = hold_index_file_for_update(&cache_file, get_index_file());
867 if (newfd < 0)
868 die("unable to create new cachefile");
869 git_config(git_default_config);
871 merge = 0;
873 reset = 0;
874 for (i = 1; i < argc; i++) {
875 const char *arg = argv[i];
876 /* "-u" means "update", meaning that a merge will update
878 * the working tree.
879 */
880 if (!strcmp(arg, "-u")) {
881 update = 1;
882 continue;
883 }
884 if (!strcmp(arg, "-v")) {
886 verbose_update = 1;
887 continue;
888 }
889 /* "-i" means "index only", meaning that a merge will
891 * not even look at the working tree.
892 */
893 if (!strcmp(arg, "-i")) {
894 index_only = 1;
895 continue;
896 }
897 /* This differs from "-m" in that we'll silently ignore
899 * unmerged entries and overwrite working tree files that
900 * correspond to them.
901 */
902 if (!strcmp(arg, "--reset")) {
903 if (stage || merge)
904 usage(read_tree_usage);
905 reset = 1;
906 merge = 1;
907 stage = 1;
908 read_cache_unmerged();
909 continue;
910 }
911 if (!strcmp(arg, "--trivial")) {
913 trivial_merges_only = 1;
914 continue;
915 }
916 if (!strcmp(arg, "--aggressive")) {
918 aggressive = 1;
919 continue;
920 }
921 /* "-m" stands for "merge", meaning we start in stage 1 */
923 if (!strcmp(arg, "-m")) {
924 if (stage || merge)
925 usage(read_tree_usage);
926 if (read_cache_unmerged())
927 die("you need to resolve your current index first");
928 stage = 1;
929 merge = 1;
930 continue;
931 }
932 /* using -u and -i at the same time makes no sense */
934 if (1 < index_only + update)
935 usage(read_tree_usage);
936 if (get_sha1(arg, sha1))
938 die("Not a valid object name %s", arg);
939 if (list_tree(sha1) < 0)
940 die("failed to unpack tree object %s", arg);
941 stage++;
942 }
943 if ((update||index_only) && !merge)
944 usage(read_tree_usage);
945 if (merge) {
947 if (stage < 2)
948 die("just how do you expect me to merge %d trees?", stage-1);
949 switch (stage - 1) {
950 case 1:
951 fn = oneway_merge;
952 break;
953 case 2:
954 fn = twoway_merge;
955 break;
956 case 3:
957 default:
958 fn = threeway_merge;
959 cache_tree_free(&active_cache_tree);
960 break;
961 }
962 if (stage - 1 >= 3)
964 head_idx = stage - 2;
965 else
966 head_idx = 1;
967 }
968 unpack_trees(fn);
970 /*
972 * When reading only one tree (either the most basic form,
973 * "-m ent" or "--reset ent" form), we can obtain a fully
974 * valid cache-tree because the index must match exactly
975 * what came from the tree.
976 */
977 if (trees && trees->item && (!merge || (stage == 2))) {
978 cache_tree_free(&active_cache_tree);
979 prime_cache_tree();
980 }
981 if (write_cache(newfd, active_cache, active_nr) ||
983 commit_index_file(&cache_file))
984 die("unable to write new index file");
985 return 0;
986}