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 "cache-tree.h"
13#include "tree-walk.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 const char *prefix = NULL;
28static int head_idx = -1;
30static int merge_size = 0;
31static struct object_list *trees = NULL;
33static struct cache_entry df_conflict_entry = {
35};
36static struct tree_entry_list df_conflict_list = {
38 .name = NULL,
39 .next = &df_conflict_list
40};
41typedef int (*merge_fn_t)(struct cache_entry **src);
43static int entcmp(const char *name1, int dir1, const char *name2, int dir2)
45{
46 int len1 = strlen(name1);
47 int len2 = strlen(name2);
48 int len = len1 < len2 ? len1 : len2;
49 int ret = memcmp(name1, name2, len);
50 unsigned char c1, c2;
51 if (ret)
52 return ret;
53 c1 = name1[len];
54 c2 = name2[len];
55 if (!c1 && dir1)
56 c1 = '/';
57 if (!c2 && dir2)
58 c2 = '/';
59 ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
60 if (c1 && c2 && !ret)
61 ret = len1 - len2;
62 return ret;
63}
64static int unpack_trees_rec(struct tree_entry_list **posns, int len,
66 const char *base, merge_fn_t fn, int *indpos)
67{
68 int baselen = strlen(base);
69 int src_size = len + 1;
70 do {
71 int i;
72 const char *first;
73 int firstdir = 0;
74 int pathlen;
75 unsigned ce_size;
76 struct tree_entry_list **subposns;
77 struct cache_entry **src;
78 int any_files = 0;
79 int any_dirs = 0;
80 char *cache_name;
81 int ce_stage;
82 /* Find the first name in the input. */
84 first = NULL;
86 cache_name = NULL;
87 /* Check the cache */
89 if (merge && *indpos < active_nr) {
90 /* This is a bit tricky: */
91 /* If the index has a subdirectory (with
92 * contents) as the first name, it'll get a
93 * filename like "foo/bar". But that's after
94 * "foo", so the entry in trees will get
95 * handled first, at which point we'll go into
96 * "foo", and deal with "bar" from the index,
97 * because the base will be "foo/". The only
98 * way we can actually have "foo/bar" first of
99 * all the things is if the trees don't
100 * contain "foo" at all, in which case we'll
101 * handle "foo/bar" without going into the
102 * directory, but that's fine (and will return
103 * an error anyway, with the added unknown
104 * file case.
105 */
106 cache_name = active_cache[*indpos]->name;
108 if (strlen(cache_name) > baselen &&
109 !memcmp(cache_name, base, baselen)) {
110 cache_name += baselen;
111 first = cache_name;
112 } else {
113 cache_name = NULL;
114 }
115 }
116#if DBRT_DEBUG > 1
118 if (first)
119 printf("index %s\n", first);
120#endif
121 for (i = 0; i < len; i++) {
122 if (!posns[i] || posns[i] == &df_conflict_list)
123 continue;
124#if DBRT_DEBUG > 1
125 printf("%d %s\n", i + 1, posns[i]->name);
126#endif
127 if (!first || entcmp(first, firstdir,
128 posns[i]->name,
129 posns[i]->directory) > 0) {
130 first = posns[i]->name;
131 firstdir = posns[i]->directory;
132 }
133 }
134 /* No name means we're done */
135 if (!first)
136 return 0;
137 pathlen = strlen(first);
139 ce_size = cache_entry_size(baselen + pathlen);
140 src = xcalloc(src_size, sizeof(struct cache_entry *));
142 subposns = xcalloc(len, sizeof(struct tree_list_entry *));
144 if (cache_name && !strcmp(cache_name, first)) {
146 any_files = 1;
147 src[0] = active_cache[*indpos];
148 remove_cache_entry_at(*indpos);
149 }
150 for (i = 0; i < len; i++) {
152 struct cache_entry *ce;
153 if (!posns[i] ||
155 (posns[i] != &df_conflict_list &&
156 strcmp(first, posns[i]->name))) {
157 continue;
158 }
159 if (posns[i] == &df_conflict_list) {
161 src[i + merge] = &df_conflict_entry;
162 continue;
163 }
164 if (posns[i]->directory) {
166 struct tree *tree = lookup_tree(posns[i]->sha1);
167 any_dirs = 1;
168 parse_tree(tree);
169 subposns[i] = create_tree_entry_list(tree);
170 posns[i] = posns[i]->next;
171 src[i + merge] = &df_conflict_entry;
172 continue;
173 }
174 if (!merge)
176 ce_stage = 0;
177 else if (i + 1 < head_idx)
178 ce_stage = 1;
179 else if (i + 1 > head_idx)
180 ce_stage = 3;
181 else
182 ce_stage = 2;
183 ce = xcalloc(1, ce_size);
185 ce->ce_mode = create_ce_mode(posns[i]->mode);
186 ce->ce_flags = create_ce_flags(baselen + pathlen,
187 ce_stage);
188 memcpy(ce->name, base, baselen);
189 memcpy(ce->name + baselen, first, pathlen + 1);
190 any_files = 1;
192 memcpy(ce->sha1, posns[i]->sha1, 20);
194 src[i + merge] = ce;
195 subposns[i] = &df_conflict_list;
196 posns[i] = posns[i]->next;
197 }
198 if (any_files) {
199 if (merge) {
200 int ret;
201#if DBRT_DEBUG > 1
203 printf("%s:\n", first);
204 for (i = 0; i < src_size; i++) {
205 printf(" %d ", i);
206 if (src[i])
207 printf("%s\n", sha1_to_hex(src[i]->sha1));
208 else
209 printf("\n");
210 }
211#endif
212 ret = fn(src);
213
214#if DBRT_DEBUG > 1
215 printf("Added %d entries\n", ret);
216#endif
217 *indpos += ret;
218 } else {
219 for (i = 0; i < src_size; i++) {
220 if (src[i]) {
221 add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
222 }
223 }
224 }
225 }
226 if (any_dirs) {
227 char *newbase = xmalloc(baselen + 2 + pathlen);
228 memcpy(newbase, base, baselen);
229 memcpy(newbase + baselen, first, pathlen);
230 newbase[baselen + pathlen] = '/';
231 newbase[baselen + pathlen + 1] = '\0';
232 if (unpack_trees_rec(subposns, len, newbase, fn,
233 indpos))
234 return -1;
235 free(newbase);
236 }
237 free(subposns);
238 free(src);
239 } while (1);
240}
241static void reject_merge(struct cache_entry *ce)
243{
244 die("Entry '%s' would be overwritten by merge. Cannot merge.",
245 ce->name);
246}
247/* Unlink the last component and attempt to remove leading
249 * directories, in case this unlink is the removal of the
250 * last entry in the directory -- empty directories are removed.
251 */
252static void unlink_entry(char *name)
253{
254 char *cp, *prev;
255 if (unlink(name))
257 return;
258 prev = NULL;
259 while (1) {
260 int status;
261 cp = strrchr(name, '/');
262 if (prev)
263 *prev = '/';
264 if (!cp)
265 break;
266 *cp = 0;
268 status = rmdir(name);
269 if (status) {
270 *cp = '/';
271 break;
272 }
273 prev = cp;
274 }
275}
276static void progress_interval(int signum)
278{
279 progress_update = 1;
280}
281static void setup_progress_signal(void)
283{
284 struct sigaction sa;
285 struct itimerval v;
286 memset(&sa, 0, sizeof(sa));
288 sa.sa_handler = progress_interval;
289 sigemptyset(&sa.sa_mask);
290 sa.sa_flags = SA_RESTART;
291 sigaction(SIGALRM, &sa, NULL);
292 v.it_interval.tv_sec = 1;
294 v.it_interval.tv_usec = 0;
295 v.it_value = v.it_interval;
296 setitimer(ITIMER_REAL, &v, NULL);
297}
298static void check_updates(struct cache_entry **src, int nr)
300{
301 static struct checkout state = {
302 .base_dir = "",
303 .force = 1,
304 .quiet = 1,
305 .refresh_cache = 1,
306 };
307 unsigned short mask = htons(CE_UPDATE);
308 unsigned last_percent = 200, cnt = 0, total = 0;
309 if (update && verbose_update) {
311 for (total = cnt = 0; cnt < nr; cnt++) {
312 struct cache_entry *ce = src[cnt];
313 if (!ce->ce_mode || ce->ce_flags & mask)
314 total++;
315 }
316 /* Don't bother doing this for very small updates */
318 if (total < 250)
319 total = 0;
320 if (total) {
322 fprintf(stderr, "Checking files out...\n");
323 setup_progress_signal();
324 progress_update = 1;
325 }
326 cnt = 0;
327 }
328 while (nr--) {
330 struct cache_entry *ce = *src++;
331 if (total) {
333 if (!ce->ce_mode || ce->ce_flags & mask) {
334 unsigned percent;
335 cnt++;
336 percent = (cnt * 100) / total;
337 if (percent != last_percent ||
338 progress_update) {
339 fprintf(stderr, "%4u%% (%u/%u) done\r",
340 percent, cnt, total);
341 last_percent = percent;
342 }
343 }
344 }
345 if (!ce->ce_mode) {
346 if (update)
347 unlink_entry(ce->name);
348 continue;
349 }
350 if (ce->ce_flags & mask) {
351 ce->ce_flags &= ~mask;
352 if (update)
353 checkout_entry(ce, &state, NULL);
354 }
355 }
356 if (total) {
357 signal(SIGALRM, SIG_IGN);
358 fputc('\n', stderr);
359 }
360}
361static int unpack_trees(merge_fn_t fn)
363{
364 int indpos = 0;
365 unsigned len = object_list_length(trees);
366 struct tree_entry_list **posns;
367 int i;
368 struct object_list *posn = trees;
369 merge_size = len;
370 if (len) {
372 posns = xmalloc(len * sizeof(struct tree_entry_list *));
373 for (i = 0; i < len; i++) {
374 posns[i] = create_tree_entry_list((struct tree *) posn->item);
375 posn = posn->next;
376 }
377 if (unpack_trees_rec(posns, len, prefix ? prefix : "",
378 fn, &indpos))
379 return -1;
380 }
381 if (trivial_merges_only && nontrivial_merge)
383 die("Merge requires file-level merging");
384 check_updates(active_cache, active_nr);
386 return 0;
387}
388static int list_tree(unsigned char *sha1)
390{
391 struct tree *tree = parse_tree_indirect(sha1);
392 if (!tree)
393 return -1;
394 object_list_append(&tree->object, &trees);
395 return 0;
396}
397static int same(struct cache_entry *a, struct cache_entry *b)
399{
400 if (!!a != !!b)
401 return 0;
402 if (!a && !b)
403 return 1;
404 return a->ce_mode == b->ce_mode &&
405 !memcmp(a->sha1, b->sha1, 20);
406}
407/*
410 * When a CE gets turned into an unmerged entry, we
411 * want it to be up-to-date
412 */
413static void verify_uptodate(struct cache_entry *ce)
414{
415 struct stat st;
416 if (index_only || reset)
418 return;
419 if (!lstat(ce->name, &st)) {
421 unsigned changed = ce_match_stat(ce, &st, 1);
422 if (!changed)
423 return;
424 errno = 0;
425 }
426 if (reset) {
427 ce->ce_flags |= htons(CE_UPDATE);
428 return;
429 }
430 if (errno == ENOENT)
431 return;
432 die("Entry '%s' not uptodate. Cannot merge.", ce->name);
433}
434static void invalidate_ce_path(struct cache_entry *ce)
436{
437 if (ce)
438 cache_tree_invalidate_path(active_cache_tree, ce->name);
439}
440/*
442 * We do not want to remove or overwrite a working tree file that
443 * is not tracked.
444 */
445static void verify_absent(const char *path, const char *action)
446{
447 struct stat st;
448 if (index_only || reset || !update)
450 return;
451 if (!lstat(path, &st))
452 die("Untracked working tree file '%s' "
453 "would be %s by merge.", path, action);
454}
455static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
457{
458 merge->ce_flags |= htons(CE_UPDATE);
459 if (old) {
460 /*
461 * See if we can re-use the old CE directly?
462 * That way we get the uptodate stat info.
463 *
464 * This also removes the UPDATE flag on
465 * a match.
466 */
467 if (same(old, merge)) {
468 *merge = *old;
469 } else {
470 verify_uptodate(old);
471 invalidate_ce_path(old);
472 }
473 }
474 else {
475 verify_absent(merge->name, "overwritten");
476 invalidate_ce_path(merge);
477 }
478 merge->ce_flags &= ~htons(CE_STAGEMASK);
480 add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
481 return 1;
482}
483static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
485{
486 if (old)
487 verify_uptodate(old);
488 else
489 verify_absent(ce->name, "removed");
490 ce->ce_mode = 0;
491 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
492 invalidate_ce_path(ce);
493 return 1;
494}
495static int keep_entry(struct cache_entry *ce)
497{
498 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
499 return 1;
500}
501#if DBRT_DEBUG
503static void show_stage_entry(FILE *o,
504 const char *label, const struct cache_entry *ce)
505{
506 if (!ce)
507 fprintf(o, "%s (missing)\n", label);
508 else
509 fprintf(o, "%s%06o %s %d\t%s\n",
510 label,
511 ntohl(ce->ce_mode),
512 sha1_to_hex(ce->sha1),
513 ce_stage(ce),
514 ce->name);
515}
516#endif
517static int threeway_merge(struct cache_entry **stages)
519{
520 struct cache_entry *index;
521 struct cache_entry *head;
522 struct cache_entry *remote = stages[head_idx + 1];
523 int count;
524 int head_match = 0;
525 int remote_match = 0;
526 const char *path = NULL;
527 int df_conflict_head = 0;
529 int df_conflict_remote = 0;
530 int any_anc_missing = 0;
532 int no_anc_exists = 1;
533 int i;
534 for (i = 1; i < head_idx; i++) {
536 if (!stages[i])
537 any_anc_missing = 1;
538 else {
539 if (!path)
540 path = stages[i]->name;
541 no_anc_exists = 0;
542 }
543 }
544 index = stages[0];
546 head = stages[head_idx];
547 if (head == &df_conflict_entry) {
549 df_conflict_head = 1;
550 head = NULL;
551 }
552 if (remote == &df_conflict_entry) {
554 df_conflict_remote = 1;
555 remote = NULL;
556 }
557 if (!path && index)
559 path = index->name;
560 if (!path && head)
561 path = head->name;
562 if (!path && remote)
563 path = remote->name;
564 /* First, if there's a #16 situation, note that to prevent #13
566 * and #14.
567 */
568 if (!same(remote, head)) {
569 for (i = 1; i < head_idx; i++) {
570 if (same(stages[i], head)) {
571 head_match = i;
572 }
573 if (same(stages[i], remote)) {
574 remote_match = i;
575 }
576 }
577 }
578 /* We start with cases where the index is allowed to match
580 * something other than the head: #14(ALT) and #2ALT, where it
581 * is permitted to match the result instead.
582 */
583 /* #14, #14ALT, #2ALT */
584 if (remote && !df_conflict_head && head_match && !remote_match) {
585 if (index && !same(index, remote) && !same(index, head))
586 reject_merge(index);
587 return merged_entry(remote, index);
588 }
589 /*
590 * If we have an entry in the index cache, then we want to
591 * make sure that it matches head.
592 */
593 if (index && !same(index, head)) {
594 reject_merge(index);
595 }
596 if (head) {
598 /* #5ALT, #15 */
599 if (same(head, remote))
600 return merged_entry(head, index);
601 /* #13, #3ALT */
602 if (!df_conflict_remote && remote_match && !head_match)
603 return merged_entry(head, index);
604 }
605 /* #1 */
607 if (!head && !remote && any_anc_missing)
608 return 0;
609 /* Under the new "aggressive" rule, we resolve mostly trivial
611 * cases that we historically had git-merge-one-file resolve.
612 */
613 if (aggressive) {
614 int head_deleted = !head && !df_conflict_head;
615 int remote_deleted = !remote && !df_conflict_remote;
616 /*
617 * Deleted in both.
618 * Deleted in one and unchanged in the other.
619 */
620 if ((head_deleted && remote_deleted) ||
621 (head_deleted && remote && remote_match) ||
622 (remote_deleted && head && head_match)) {
623 if (index)
624 return deleted_entry(index, index);
625 else if (path)
626 verify_absent(path, "removed");
627 return 0;
628 }
629 /*
630 * Added in both, identically.
631 */
632 if (no_anc_exists && head && remote && same(head, remote))
633 return merged_entry(head, index);
634 }
636 /* Below are "no merge" cases, which require that the index be
638 * up-to-date to avoid the files getting overwritten with
639 * conflict resolution files.
640 */
641 if (index) {
642 verify_uptodate(index);
643 }
644 else if (path)
645 verify_absent(path, "overwritten");
646 nontrivial_merge = 1;
648 /* #2, #3, #4, #6, #7, #9, #11. */
650 count = 0;
651 if (!head_match || !remote_match) {
652 for (i = 1; i < head_idx; i++) {
653 if (stages[i]) {
654 keep_entry(stages[i]);
655 count++;
656 break;
657 }
658 }
659 }
660#if DBRT_DEBUG
661 else {
662 fprintf(stderr, "read-tree: warning #16 detected\n");
663 show_stage_entry(stderr, "head ", stages[head_match]);
664 show_stage_entry(stderr, "remote ", stages[remote_match]);
665 }
666#endif
667 if (head) { count += keep_entry(head); }
668 if (remote) { count += keep_entry(remote); }
669 return count;
670}
671/*
673 * Two-way merge.
674 *
675 * The rule is to "carry forward" what is in the index without losing
676 * information across a "fast forward", favoring a successful merge
677 * over a merge failure when it makes sense. For details of the
678 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
679 *
680 */
681static int twoway_merge(struct cache_entry **src)
682{
683 struct cache_entry *current = src[0];
684 struct cache_entry *oldtree = src[1], *newtree = src[2];
685 if (merge_size != 2)
687 return error("Cannot do a twoway merge of %d trees",
688 merge_size);
689 if (current) {
691 if ((!oldtree && !newtree) || /* 4 and 5 */
692 (!oldtree && newtree &&
693 same(current, newtree)) || /* 6 and 7 */
694 (oldtree && newtree &&
695 same(oldtree, newtree)) || /* 14 and 15 */
696 (oldtree && newtree &&
697 !same(oldtree, newtree) && /* 18 and 19*/
698 same(current, newtree))) {
699 return keep_entry(current);
700 }
701 else if (oldtree && !newtree && same(current, oldtree)) {
702 /* 10 or 11 */
703 return deleted_entry(oldtree, current);
704 }
705 else if (oldtree && newtree &&
706 same(current, oldtree) && !same(current, newtree)) {
707 /* 20 or 21 */
708 return merged_entry(newtree, current);
709 }
710 else {
711 /* all other failures */
712 if (oldtree)
713 reject_merge(oldtree);
714 if (current)
715 reject_merge(current);
716 if (newtree)
717 reject_merge(newtree);
718 return -1;
719 }
720 }
721 else if (newtree)
722 return merged_entry(newtree, current);
723 else
724 return deleted_entry(oldtree, current);
725}
726/*
728 * Bind merge.
729 *
730 * Keep the index entries at stage0, collapse stage1 but make sure
731 * stage0 does not have anything there.
732 */
733static int bind_merge(struct cache_entry **src)
734{
735 struct cache_entry *old = src[0];
736 struct cache_entry *a = src[1];
737 if (merge_size != 1)
739 return error("Cannot do a bind merge of %d trees\n",
740 merge_size);
741 if (a && old)
742 die("Entry '%s' overlaps. Cannot bind.", a->name);
743 if (!a)
744 return keep_entry(old);
745 else
746 return merged_entry(a, NULL);
747}
748/*
750 * One-way merge.
751 *
752 * The rule is:
753 * - take the stat information from stage0, take the data from stage1
754 */
755static int oneway_merge(struct cache_entry **src)
756{
757 struct cache_entry *old = src[0];
758 struct cache_entry *a = src[1];
759 if (merge_size != 1)
761 return error("Cannot do a oneway merge of %d trees",
762 merge_size);
763 if (!a) {
765 invalidate_ce_path(old);
766 return deleted_entry(old, old);
767 }
768 if (old && same(old, a)) {
769 if (reset) {
770 struct stat st;
771 if (lstat(old->name, &st) ||
772 ce_match_stat(old, &st, 1))
773 old->ce_flags |= htons(CE_UPDATE);
774 }
775 return keep_entry(old);
776 }
777 return merged_entry(a, old);
778}
779static int read_cache_unmerged(void)
781{
782 int i, deleted;
783 struct cache_entry **dst;
784 read_cache();
786 dst = active_cache;
787 deleted = 0;
788 for (i = 0; i < active_nr; i++) {
789 struct cache_entry *ce = active_cache[i];
790 if (ce_stage(ce)) {
791 deleted++;
792 invalidate_ce_path(ce);
793 continue;
794 }
795 if (deleted)
796 *dst = ce;
797 dst++;
798 }
799 active_nr -= deleted;
800 return deleted;
801}
802static void prime_cache_tree_rec(struct cache_tree *it, struct tree *tree)
804{
805 struct tree_desc desc;
806 int cnt = 0;
807 memcpy(it->sha1, tree->object.sha1, 20);
809 desc.buf = tree->buffer;
810 desc.size = tree->size;
811 while (desc.size) {
813 unsigned mode;
814 const char *name;
815 const unsigned char *sha1;
816 sha1 = tree_entry_extract(&desc, &name, &mode);
818 update_tree_entry(&desc);
819 if (!S_ISDIR(mode))
821 cnt++;
822 else {
823 struct cache_tree_sub *sub;
824 struct tree *subtree;
825 subtree = lookup_tree(sha1);
827 if (!subtree->object.parsed)
828 parse_tree(subtree);
829 sub = cache_tree_sub(it, name);
830 sub->cache_tree = cache_tree();
831 prime_cache_tree_rec(sub->cache_tree, subtree);
832 cnt += sub->cache_tree->entry_count;
833 }
834 }
835 it->entry_count = cnt;
836}
837static void prime_cache_tree(void)
839{
840 struct tree *tree = (struct tree *)trees->item;
841 if (!tree)
842 return;
843 active_cache_tree = cache_tree();
844 prime_cache_tree_rec(active_cache_tree, tree);
845}
847static const char read_tree_usage[] = "git-read-tree (<sha> | [[-m [--aggressive] | --reset | --prefix=<prefix>] [-u | -i]] <sha1> [<sha2> [<sha3>]])";
849static struct cache_file cache_file;
851int cmd_read_tree(int argc, const char **argv, char **envp)
853{
854 int i, newfd, stage = 0;
855 unsigned char sha1[20];
856 merge_fn_t fn = NULL;
857 setup_git_directory();
859 git_config(git_default_config);
860 newfd = hold_index_file_for_update(&cache_file, get_index_file());
862 if (newfd < 0)
863 die("unable to create new cachefile");
864 git_config(git_default_config);
866 merge = 0;
868 reset = 0;
869 for (i = 1; i < argc; i++) {
870 const char *arg = argv[i];
871 /* "-u" means "update", meaning that a merge will update
873 * the working tree.
874 */
875 if (!strcmp(arg, "-u")) {
876 update = 1;
877 continue;
878 }
879 if (!strcmp(arg, "-v")) {
881 verbose_update = 1;
882 continue;
883 }
884 /* "-i" means "index only", meaning that a merge will
886 * not even look at the working tree.
887 */
888 if (!strcmp(arg, "-i")) {
889 index_only = 1;
890 continue;
891 }
892 /* "--prefix=<subdirectory>/" means keep the current index
894 * entries and put the entries from the tree under the
895 * given subdirectory.
896 */
897 if (!strncmp(arg, "--prefix=", 9)) {
898 if (stage || merge || prefix)
899 usage(read_tree_usage);
900 prefix = arg + 9;
901 merge = 1;
902 stage = 1;
903 if (read_cache_unmerged())
904 die("you need to resolve your current index first");
905 continue;
906 }
907 /* This differs from "-m" in that we'll silently ignore unmerged entries */
909 if (!strcmp(arg, "--reset")) {
910 if (stage || merge || prefix)
911 usage(read_tree_usage);
912 reset = 1;
913 merge = 1;
914 stage = 1;
915 read_cache_unmerged();
916 continue;
917 }
918 if (!strcmp(arg, "--trivial")) {
920 trivial_merges_only = 1;
921 continue;
922 }
923 if (!strcmp(arg, "--aggressive")) {
925 aggressive = 1;
926 continue;
927 }
928 /* "-m" stands for "merge", meaning we start in stage 1 */
930 if (!strcmp(arg, "-m")) {
931 if (stage || merge || prefix)
932 usage(read_tree_usage);
933 if (read_cache_unmerged())
934 die("you need to resolve your current index first");
935 stage = 1;
936 merge = 1;
937 continue;
938 }
939 /* using -u and -i at the same time makes no sense */
941 if (1 < index_only + update)
942 usage(read_tree_usage);
943 if (get_sha1(arg, sha1))
945 die("Not a valid object name %s", arg);
946 if (list_tree(sha1) < 0)
947 die("failed to unpack tree object %s", arg);
948 stage++;
949 }
950 if ((update||index_only) && !merge)
951 usage(read_tree_usage);
952 if (prefix) {
954 int pfxlen = strlen(prefix);
955 int pos;
956 if (prefix[pfxlen-1] != '/')
957 die("prefix must end with /");
958 if (stage != 2)
959 die("binding merge takes only one tree");
960 pos = cache_name_pos(prefix, pfxlen);
961 if (0 <= pos)
962 die("corrupt index file");
963 pos = -pos-1;
964 if (pos < active_nr &&
965 !strncmp(active_cache[pos]->name, prefix, pfxlen))
966 die("subdirectory '%s' already exists.", prefix);
967 pos = cache_name_pos(prefix, pfxlen-1);
968 if (0 <= pos)
969 die("file '%.*s' already exists.", pfxlen-1, prefix);
970 }
971 if (merge) {
973 if (stage < 2)
974 die("just how do you expect me to merge %d trees?", stage-1);
975 switch (stage - 1) {
976 case 1:
977 fn = prefix ? bind_merge : oneway_merge;
978 break;
979 case 2:
980 fn = twoway_merge;
981 break;
982 case 3:
983 default:
984 fn = threeway_merge;
985 cache_tree_free(&active_cache_tree);
986 break;
987 }
988 if (stage - 1 >= 3)
990 head_idx = stage - 2;
991 else
992 head_idx = 1;
993 }
994 unpack_trees(fn);
996 /*
998 * When reading only one tree (either the most basic form,
999 * "-m ent" or "--reset ent" form), we can obtain a fully
1000 * valid cache-tree because the index must match exactly
1001 * what came from the tree.
1002 */
1003 if (trees && trees->item && (!merge || (stage == 2))) {
1004 cache_tree_free(&active_cache_tree);
1005 prime_cache_tree();
1006 }
1007 if (write_cache(newfd, active_cache, active_nr) ||
1009 commit_index_file(&cache_file))
1010 die("unable to write new index file");
1011 return 0;
1012}