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 progress_update = 0;
380 }
381 }
382 }
383 if (!ce->ce_mode) {
384 if (update)
385 unlink_entry(ce->name);
386 continue;
387 }
388 if (ce->ce_flags & mask) {
389 ce->ce_flags &= ~mask;
390 if (update)
391 checkout_entry(ce, &state, NULL);
392 }
393 }
394 if (total) {
395 signal(SIGALRM, SIG_IGN);
396 fputc('\n', stderr);
397 }
398}
399static int unpack_trees(merge_fn_t fn)
401{
402 int indpos = 0;
403 unsigned len = object_list_length(trees);
404 struct tree_entry_list **posns;
405 int i;
406 struct object_list *posn = trees;
407 merge_size = len;
408 if (len) {
410 posns = xmalloc(len * sizeof(struct tree_entry_list *));
411 for (i = 0; i < len; i++) {
412 posns[i] = create_tree_entry_list((struct tree *) posn->item);
413 posn = posn->next;
414 }
415 if (unpack_trees_rec(posns, len, "", fn, &indpos))
416 return -1;
417 }
418 if (trivial_merges_only && nontrivial_merge)
420 die("Merge requires file-level merging");
421 check_updates(active_cache, active_nr);
423 return 0;
424}
425static int list_tree(unsigned char *sha1)
427{
428 struct tree *tree = parse_tree_indirect(sha1);
429 if (!tree)
430 return -1;
431 object_list_append(&tree->object, &trees);
432 return 0;
433}
434static int same(struct cache_entry *a, struct cache_entry *b)
436{
437 if (!!a != !!b)
438 return 0;
439 if (!a && !b)
440 return 1;
441 return a->ce_mode == b->ce_mode &&
442 !memcmp(a->sha1, b->sha1, 20);
443}
444/*
447 * When a CE gets turned into an unmerged entry, we
448 * want it to be up-to-date
449 */
450static void verify_uptodate(struct cache_entry *ce)
451{
452 struct stat st;
453 if (index_only || reset)
455 return;
456 if (!lstat(ce->name, &st)) {
458 unsigned changed = ce_match_stat(ce, &st, 1);
459 if (!changed)
460 return;
461 errno = 0;
462 }
463 if (reset) {
464 ce->ce_flags |= htons(CE_UPDATE);
465 return;
466 }
467 if (errno == ENOENT)
468 return;
469 die("Entry '%s' not uptodate. Cannot merge.", ce->name);
470}
471static void invalidate_ce_path(struct cache_entry *ce)
473{
474 if (ce)
475 cache_tree_invalidate_path(active_cache_tree, ce->name);
476}
477/*
479 * We do not want to remove or overwrite a working tree file that
480 * is not tracked.
481 */
482static void verify_absent(const char *path, const char *action)
483{
484 struct stat st;
485 if (index_only || reset || !update)
487 return;
488 if (!lstat(path, &st))
489 die("Untracked working tree file '%s' "
490 "would be %s by merge.", path, action);
491}
492static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
494{
495 merge->ce_flags |= htons(CE_UPDATE);
496 if (old) {
497 /*
498 * See if we can re-use the old CE directly?
499 * That way we get the uptodate stat info.
500 *
501 * This also removes the UPDATE flag on
502 * a match.
503 */
504 if (same(old, merge)) {
505 *merge = *old;
506 } else {
507 verify_uptodate(old);
508 invalidate_ce_path(old);
509 }
510 }
511 else {
512 verify_absent(merge->name, "overwritten");
513 invalidate_ce_path(merge);
514 }
515 merge->ce_flags &= ~htons(CE_STAGEMASK);
517 add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
518 return 1;
519}
520static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
522{
523 if (old)
524 verify_uptodate(old);
525 else
526 verify_absent(ce->name, "removed");
527 ce->ce_mode = 0;
528 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
529 invalidate_ce_path(ce);
530 return 1;
531}
532static int keep_entry(struct cache_entry *ce)
534{
535 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
536 return 1;
537}
538#if DBRT_DEBUG
540static void show_stage_entry(FILE *o,
541 const char *label, const struct cache_entry *ce)
542{
543 if (!ce)
544 fprintf(o, "%s (missing)\n", label);
545 else
546 fprintf(o, "%s%06o %s %d\t%s\n",
547 label,
548 ntohl(ce->ce_mode),
549 sha1_to_hex(ce->sha1),
550 ce_stage(ce),
551 ce->name);
552}
553#endif
554static int threeway_merge(struct cache_entry **stages)
556{
557 struct cache_entry *index;
558 struct cache_entry *head;
559 struct cache_entry *remote = stages[head_idx + 1];
560 int count;
561 int head_match = 0;
562 int remote_match = 0;
563 const char *path = NULL;
564 int df_conflict_head = 0;
566 int df_conflict_remote = 0;
567 int any_anc_missing = 0;
569 int no_anc_exists = 1;
570 int i;
571 for (i = 1; i < head_idx; i++) {
573 if (!stages[i])
574 any_anc_missing = 1;
575 else {
576 if (!path)
577 path = stages[i]->name;
578 no_anc_exists = 0;
579 }
580 }
581 index = stages[0];
583 head = stages[head_idx];
584 if (head == &df_conflict_entry) {
586 df_conflict_head = 1;
587 head = NULL;
588 }
589 if (remote == &df_conflict_entry) {
591 df_conflict_remote = 1;
592 remote = NULL;
593 }
594 if (!path && index)
596 path = index->name;
597 if (!path && head)
598 path = head->name;
599 if (!path && remote)
600 path = remote->name;
601 /* First, if there's a #16 situation, note that to prevent #13
603 * and #14.
604 */
605 if (!same(remote, head)) {
606 for (i = 1; i < head_idx; i++) {
607 if (same(stages[i], head)) {
608 head_match = i;
609 }
610 if (same(stages[i], remote)) {
611 remote_match = i;
612 }
613 }
614 }
615 /* We start with cases where the index is allowed to match
617 * something other than the head: #14(ALT) and #2ALT, where it
618 * is permitted to match the result instead.
619 */
620 /* #14, #14ALT, #2ALT */
621 if (remote && !df_conflict_head && head_match && !remote_match) {
622 if (index && !same(index, remote) && !same(index, head))
623 reject_merge(index);
624 return merged_entry(remote, index);
625 }
626 /*
627 * If we have an entry in the index cache, then we want to
628 * make sure that it matches head.
629 */
630 if (index && !same(index, head)) {
631 reject_merge(index);
632 }
633 if (head) {
635 /* #5ALT, #15 */
636 if (same(head, remote))
637 return merged_entry(head, index);
638 /* #13, #3ALT */
639 if (!df_conflict_remote && remote_match && !head_match)
640 return merged_entry(head, index);
641 }
642 /* #1 */
644 if (!head && !remote && any_anc_missing)
645 return 0;
646 /* Under the new "aggressive" rule, we resolve mostly trivial
648 * cases that we historically had git-merge-one-file resolve.
649 */
650 if (aggressive) {
651 int head_deleted = !head && !df_conflict_head;
652 int remote_deleted = !remote && !df_conflict_remote;
653 /*
654 * Deleted in both.
655 * Deleted in one and unchanged in the other.
656 */
657 if ((head_deleted && remote_deleted) ||
658 (head_deleted && remote && remote_match) ||
659 (remote_deleted && head && head_match)) {
660 if (index)
661 return deleted_entry(index, index);
662 else if (path)
663 verify_absent(path, "removed");
664 return 0;
665 }
666 /*
667 * Added in both, identically.
668 */
669 if (no_anc_exists && head && remote && same(head, remote))
670 return merged_entry(head, index);
671 }
673 /* Below are "no merge" cases, which require that the index be
675 * up-to-date to avoid the files getting overwritten with
676 * conflict resolution files.
677 */
678 if (index) {
679 verify_uptodate(index);
680 }
681 else if (path)
682 verify_absent(path, "overwritten");
683 nontrivial_merge = 1;
685 /* #2, #3, #4, #6, #7, #9, #11. */
687 count = 0;
688 if (!head_match || !remote_match) {
689 for (i = 1; i < head_idx; i++) {
690 if (stages[i]) {
691 keep_entry(stages[i]);
692 count++;
693 break;
694 }
695 }
696 }
697#if DBRT_DEBUG
698 else {
699 fprintf(stderr, "read-tree: warning #16 detected\n");
700 show_stage_entry(stderr, "head ", stages[head_match]);
701 show_stage_entry(stderr, "remote ", stages[remote_match]);
702 }
703#endif
704 if (head) { count += keep_entry(head); }
705 if (remote) { count += keep_entry(remote); }
706 return count;
707}
708/*
710 * Two-way merge.
711 *
712 * The rule is to "carry forward" what is in the index without losing
713 * information across a "fast forward", favoring a successful merge
714 * over a merge failure when it makes sense. For details of the
715 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
716 *
717 */
718static int twoway_merge(struct cache_entry **src)
719{
720 struct cache_entry *current = src[0];
721 struct cache_entry *oldtree = src[1], *newtree = src[2];
722 if (merge_size != 2)
724 return error("Cannot do a twoway merge of %d trees",
725 merge_size);
726 if (current) {
728 if ((!oldtree && !newtree) || /* 4 and 5 */
729 (!oldtree && newtree &&
730 same(current, newtree)) || /* 6 and 7 */
731 (oldtree && newtree &&
732 same(oldtree, newtree)) || /* 14 and 15 */
733 (oldtree && newtree &&
734 !same(oldtree, newtree) && /* 18 and 19*/
735 same(current, newtree))) {
736 return keep_entry(current);
737 }
738 else if (oldtree && !newtree && same(current, oldtree)) {
739 /* 10 or 11 */
740 return deleted_entry(oldtree, current);
741 }
742 else if (oldtree && newtree &&
743 same(current, oldtree) && !same(current, newtree)) {
744 /* 20 or 21 */
745 return merged_entry(newtree, current);
746 }
747 else {
748 /* all other failures */
749 if (oldtree)
750 reject_merge(oldtree);
751 if (current)
752 reject_merge(current);
753 if (newtree)
754 reject_merge(newtree);
755 return -1;
756 }
757 }
758 else if (newtree)
759 return merged_entry(newtree, current);
760 else
761 return deleted_entry(oldtree, current);
762}
763/*
765 * One-way merge.
766 *
767 * The rule is:
768 * - take the stat information from stage0, take the data from stage1
769 */
770static int oneway_merge(struct cache_entry **src)
771{
772 struct cache_entry *old = src[0];
773 struct cache_entry *a = src[1];
774 if (merge_size != 1)
776 return error("Cannot do a oneway merge of %d trees",
777 merge_size);
778 if (!a)
780 return deleted_entry(old, old);
781 if (old && same(old, a)) {
782 if (reset) {
783 struct stat st;
784 if (lstat(old->name, &st) ||
785 ce_match_stat(old, &st, 1))
786 old->ce_flags |= htons(CE_UPDATE);
787 }
788 return keep_entry(old);
789 }
790 return merged_entry(a, old);
791}
792static int read_cache_unmerged(void)
794{
795 int i;
796 struct cache_entry **dst;
797 struct cache_entry *last = NULL;
798 read_cache();
800 dst = active_cache;
801 for (i = 0; i < active_nr; i++) {
802 struct cache_entry *ce = active_cache[i];
803 if (ce_stage(ce)) {
804 if (last && !strcmp(ce->name, last->name))
805 continue;
806 invalidate_ce_path(ce);
807 last = ce;
808 ce->ce_mode = 0;
809 ce->ce_flags &= ~htons(CE_STAGEMASK);
810 }
811 *dst++ = ce;
812 }
813 active_nr = dst - active_cache;
814 return !!last;
815}
816static void prime_cache_tree_rec(struct cache_tree *it, struct tree *tree)
818{
819 struct tree_desc desc;
820 struct name_entry entry;
821 int cnt;
822 memcpy(it->sha1, tree->object.sha1, 20);
824 desc.buf = tree->buffer;
825 desc.size = tree->size;
826 cnt = 0;
827 while (tree_entry(&desc, &entry)) {
828 if (!S_ISDIR(entry.mode))
829 cnt++;
830 else {
831 struct cache_tree_sub *sub;
832 struct tree *subtree = lookup_tree(entry.sha1);
833 if (!subtree->object.parsed)
834 parse_tree(subtree);
835 sub = cache_tree_sub(it, entry.path);
836 sub->cache_tree = cache_tree();
837 prime_cache_tree_rec(sub->cache_tree, subtree);
838 cnt += sub->cache_tree->entry_count;
839 }
840 }
841 it->entry_count = cnt;
842}
843static void prime_cache_tree(void)
845{
846 struct tree *tree = (struct tree *)trees->item;
847 if (!tree)
848 return;
849 active_cache_tree = cache_tree();
850 prime_cache_tree_rec(active_cache_tree, tree);
851}
853static const char read_tree_usage[] = "git-read-tree (<sha> | -m [--aggressive] [-u | -i] <sha1> [<sha2> [<sha3>]])";
855static struct cache_file cache_file;
857int cmd_read_tree(int argc, const char **argv, char **envp)
859{
860 int i, newfd, stage = 0;
861 unsigned char sha1[20];
862 merge_fn_t fn = NULL;
863 setup_git_directory();
865 git_config(git_default_config);
866 newfd = hold_index_file_for_update(&cache_file, get_index_file());
868 if (newfd < 0)
869 die("unable to create new cachefile");
870 git_config(git_default_config);
872 merge = 0;
874 reset = 0;
875 for (i = 1; i < argc; i++) {
876 const char *arg = argv[i];
877 /* "-u" means "update", meaning that a merge will update
879 * the working tree.
880 */
881 if (!strcmp(arg, "-u")) {
882 update = 1;
883 continue;
884 }
885 if (!strcmp(arg, "-v")) {
887 verbose_update = 1;
888 continue;
889 }
890 /* "-i" means "index only", meaning that a merge will
892 * not even look at the working tree.
893 */
894 if (!strcmp(arg, "-i")) {
895 index_only = 1;
896 continue;
897 }
898 /* This differs from "-m" in that we'll silently ignore
900 * unmerged entries and overwrite working tree files that
901 * correspond to them.
902 */
903 if (!strcmp(arg, "--reset")) {
904 if (stage || merge)
905 usage(read_tree_usage);
906 reset = 1;
907 merge = 1;
908 stage = 1;
909 read_cache_unmerged();
910 continue;
911 }
912 if (!strcmp(arg, "--trivial")) {
914 trivial_merges_only = 1;
915 continue;
916 }
917 if (!strcmp(arg, "--aggressive")) {
919 aggressive = 1;
920 continue;
921 }
922 /* "-m" stands for "merge", meaning we start in stage 1 */
924 if (!strcmp(arg, "-m")) {
925 if (stage || merge)
926 usage(read_tree_usage);
927 if (read_cache_unmerged())
928 die("you need to resolve your current index first");
929 stage = 1;
930 merge = 1;
931 continue;
932 }
933 /* using -u and -i at the same time makes no sense */
935 if (1 < index_only + update)
936 usage(read_tree_usage);
937 if (get_sha1(arg, sha1))
939 die("Not a valid object name %s", arg);
940 if (list_tree(sha1) < 0)
941 die("failed to unpack tree object %s", arg);
942 stage++;
943 }
944 if ((update||index_only) && !merge)
945 usage(read_tree_usage);
946 if (merge) {
948 if (stage < 2)
949 die("just how do you expect me to merge %d trees?", stage-1);
950 switch (stage - 1) {
951 case 1:
952 fn = oneway_merge;
953 break;
954 case 2:
955 fn = twoway_merge;
956 break;
957 case 3:
958 default:
959 fn = threeway_merge;
960 cache_tree_free(&active_cache_tree);
961 break;
962 }
963 if (stage - 1 >= 3)
965 head_idx = stage - 2;
966 else
967 head_idx = 1;
968 }
969 unpack_trees(fn);
971 /*
973 * When reading only one tree (either the most basic form,
974 * "-m ent" or "--reset ent" form), we can obtain a fully
975 * valid cache-tree because the index must match exactly
976 * what came from the tree.
977 */
978 if (trees && trees->item && (!merge || (stage == 2))) {
979 cache_tree_free(&active_cache_tree);
980 prime_cache_tree();
981 }
982 if (write_cache(newfd, active_cache, active_nr) ||
984 commit_index_file(&cache_file))
985 die("unable to write new index file");
986 return 0;
987}