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};
35static struct tree_entry_list df_conflict_list = {
37 .name = NULL,
38 .next = &df_conflict_list
39};
40typedef int (*merge_fn_t)(struct cache_entry **src);
42static int entcmp(const char *name1, int dir1, const char *name2, int dir2)
44{
45 int len1 = strlen(name1);
46 int len2 = strlen(name2);
47 int len = len1 < len2 ? len1 : len2;
48 int ret = memcmp(name1, name2, len);
49 unsigned char c1, c2;
50 if (ret)
51 return ret;
52 c1 = name1[len];
53 c2 = name2[len];
54 if (!c1 && dir1)
55 c1 = '/';
56 if (!c2 && dir2)
57 c2 = '/';
58 ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
59 if (c1 && c2 && !ret)
60 ret = len1 - len2;
61 return ret;
62}
63static int unpack_trees_rec(struct tree_entry_list **posns, int len,
65 const char *base, merge_fn_t fn, int *indpos)
66{
67 int baselen = strlen(base);
68 int src_size = len + 1;
69 do {
70 int i;
71 const char *first;
72 int firstdir = 0;
73 int pathlen;
74 unsigned ce_size;
75 struct tree_entry_list **subposns;
76 struct cache_entry **src;
77 int any_files = 0;
78 int any_dirs = 0;
79 char *cache_name;
80 int ce_stage;
81 /* Find the first name in the input. */
83 first = NULL;
85 cache_name = NULL;
86 /* Check the cache */
88 if (merge && *indpos < active_nr) {
89 /* This is a bit tricky: */
90 /* If the index has a subdirectory (with
91 * contents) as the first name, it'll get a
92 * filename like "foo/bar". But that's after
93 * "foo", so the entry in trees will get
94 * handled first, at which point we'll go into
95 * "foo", and deal with "bar" from the index,
96 * because the base will be "foo/". The only
97 * way we can actually have "foo/bar" first of
98 * all the things is if the trees don't
99 * contain "foo" at all, in which case we'll
100 * handle "foo/bar" without going into the
101 * directory, but that's fine (and will return
102 * an error anyway, with the added unknown
103 * file case.
104 */
105 cache_name = active_cache[*indpos]->name;
107 if (strlen(cache_name) > baselen &&
108 !memcmp(cache_name, base, baselen)) {
109 cache_name += baselen;
110 first = cache_name;
111 } else {
112 cache_name = NULL;
113 }
114 }
115#if DBRT_DEBUG > 1
117 if (first)
118 printf("index %s\n", first);
119#endif
120 for (i = 0; i < len; i++) {
121 if (!posns[i] || posns[i] == &df_conflict_list)
122 continue;
123#if DBRT_DEBUG > 1
124 printf("%d %s\n", i + 1, posns[i]->name);
125#endif
126 if (!first || entcmp(first, firstdir,
127 posns[i]->name,
128 posns[i]->directory) > 0) {
129 first = posns[i]->name;
130 firstdir = posns[i]->directory;
131 }
132 }
133 /* No name means we're done */
134 if (!first)
135 return 0;
136 pathlen = strlen(first);
138 ce_size = cache_entry_size(baselen + pathlen);
139 src = xcalloc(src_size, sizeof(struct cache_entry *));
141 subposns = xcalloc(len, sizeof(struct tree_list_entry *));
143 if (cache_name && !strcmp(cache_name, first)) {
145 any_files = 1;
146 src[0] = active_cache[*indpos];
147 remove_cache_entry_at(*indpos);
148 }
149 for (i = 0; i < len; i++) {
151 struct cache_entry *ce;
152 if (!posns[i] ||
154 (posns[i] != &df_conflict_list &&
155 strcmp(first, posns[i]->name))) {
156 continue;
157 }
158 if (posns[i] == &df_conflict_list) {
160 src[i + merge] = &df_conflict_entry;
161 continue;
162 }
163 if (posns[i]->directory) {
165 struct tree *tree = lookup_tree(posns[i]->sha1);
166 any_dirs = 1;
167 parse_tree(tree);
168 subposns[i] = create_tree_entry_list(tree);
169 posns[i] = posns[i]->next;
170 src[i + merge] = &df_conflict_entry;
171 continue;
172 }
173 if (!merge)
175 ce_stage = 0;
176 else if (i + 1 < head_idx)
177 ce_stage = 1;
178 else if (i + 1 > head_idx)
179 ce_stage = 3;
180 else
181 ce_stage = 2;
182 ce = xcalloc(1, ce_size);
184 ce->ce_mode = create_ce_mode(posns[i]->mode);
185 ce->ce_flags = create_ce_flags(baselen + pathlen,
186 ce_stage);
187 memcpy(ce->name, base, baselen);
188 memcpy(ce->name + baselen, first, pathlen + 1);
189 any_files = 1;
191 memcpy(ce->sha1, posns[i]->sha1, 20);
193 src[i + merge] = ce;
194 subposns[i] = &df_conflict_list;
195 posns[i] = posns[i]->next;
196 }
197 if (any_files) {
198 if (merge) {
199 int ret;
200#if DBRT_DEBUG > 1
202 printf("%s:\n", first);
203 for (i = 0; i < src_size; i++) {
204 printf(" %d ", i);
205 if (src[i])
206 printf("%s\n", sha1_to_hex(src[i]->sha1));
207 else
208 printf("\n");
209 }
210#endif
211 ret = fn(src);
212
213#if DBRT_DEBUG > 1
214 printf("Added %d entries\n", ret);
215#endif
216 *indpos += ret;
217 } else {
218 for (i = 0; i < src_size; i++) {
219 if (src[i]) {
220 add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
221 }
222 }
223 }
224 }
225 if (any_dirs) {
226 char *newbase = xmalloc(baselen + 2 + pathlen);
227 memcpy(newbase, base, baselen);
228 memcpy(newbase + baselen, first, pathlen);
229 newbase[baselen + pathlen] = '/';
230 newbase[baselen + pathlen + 1] = '\0';
231 if (unpack_trees_rec(subposns, len, newbase, fn,
232 indpos))
233 return -1;
234 free(newbase);
235 }
236 free(subposns);
237 free(src);
238 } while (1);
239}
240static void reject_merge(struct cache_entry *ce)
242{
243 die("Entry '%s' would be overwritten by merge. Cannot merge.",
244 ce->name);
245}
246/* Unlink the last component and attempt to remove leading
248 * directories, in case this unlink is the removal of the
249 * last entry in the directory -- empty directories are removed.
250 */
251static void unlink_entry(char *name)
252{
253 char *cp, *prev;
254 if (unlink(name))
256 return;
257 prev = NULL;
258 while (1) {
259 int status;
260 cp = strrchr(name, '/');
261 if (prev)
262 *prev = '/';
263 if (!cp)
264 break;
265 *cp = 0;
267 status = rmdir(name);
268 if (status) {
269 *cp = '/';
270 break;
271 }
272 prev = cp;
273 }
274}
275static void progress_interval(int signum)
277{
278 progress_update = 1;
279}
280static void setup_progress_signal(void)
282{
283 struct sigaction sa;
284 struct itimerval v;
285 memset(&sa, 0, sizeof(sa));
287 sa.sa_handler = progress_interval;
288 sigemptyset(&sa.sa_mask);
289 sa.sa_flags = SA_RESTART;
290 sigaction(SIGALRM, &sa, NULL);
291 v.it_interval.tv_sec = 1;
293 v.it_interval.tv_usec = 0;
294 v.it_value = v.it_interval;
295 setitimer(ITIMER_REAL, &v, NULL);
296}
297static void check_updates(struct cache_entry **src, int nr)
299{
300 static struct checkout state = {
301 .base_dir = "",
302 .force = 1,
303 .quiet = 1,
304 .refresh_cache = 1,
305 };
306 unsigned short mask = htons(CE_UPDATE);
307 unsigned last_percent = 200, cnt = 0, total = 0;
308 if (update && verbose_update) {
310 for (total = cnt = 0; cnt < nr; cnt++) {
311 struct cache_entry *ce = src[cnt];
312 if (!ce->ce_mode || ce->ce_flags & mask)
313 total++;
314 }
315 /* Don't bother doing this for very small updates */
317 if (total < 250)
318 total = 0;
319 if (total) {
321 fprintf(stderr, "Checking files out...\n");
322 setup_progress_signal();
323 progress_update = 1;
324 }
325 cnt = 0;
326 }
327 while (nr--) {
329 struct cache_entry *ce = *src++;
330 if (total) {
332 if (!ce->ce_mode || ce->ce_flags & mask) {
333 unsigned percent;
334 cnt++;
335 percent = (cnt * 100) / total;
336 if (percent != last_percent ||
337 progress_update) {
338 fprintf(stderr, "%4u%% (%u/%u) done\r",
339 percent, cnt, total);
340 last_percent = percent;
341 }
342 }
343 }
344 if (!ce->ce_mode) {
345 if (update)
346 unlink_entry(ce->name);
347 continue;
348 }
349 if (ce->ce_flags & mask) {
350 ce->ce_flags &= ~mask;
351 if (update)
352 checkout_entry(ce, &state, NULL);
353 }
354 }
355 if (total) {
356 signal(SIGALRM, SIG_IGN);
357 fputc('\n', stderr);
358 }
359}
360static int unpack_trees(merge_fn_t fn)
362{
363 int indpos = 0;
364 unsigned len = object_list_length(trees);
365 struct tree_entry_list **posns;
366 int i;
367 struct object_list *posn = trees;
368 merge_size = len;
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((struct tree *) posn->item);
374 posn = posn->next;
375 }
376 if (unpack_trees_rec(posns, len, "", fn, &indpos))
377 return -1;
378 }
379 if (trivial_merges_only && nontrivial_merge)
381 die("Merge requires file-level merging");
382 check_updates(active_cache, active_nr);
384 return 0;
385}
386static int list_tree(unsigned char *sha1)
388{
389 struct tree *tree = parse_tree_indirect(sha1);
390 if (!tree)
391 return -1;
392 object_list_append(&tree->object, &trees);
393 return 0;
394}
395static int same(struct cache_entry *a, struct cache_entry *b)
397{
398 if (!!a != !!b)
399 return 0;
400 if (!a && !b)
401 return 1;
402 return a->ce_mode == b->ce_mode &&
403 !memcmp(a->sha1, b->sha1, 20);
404}
405/*
408 * When a CE gets turned into an unmerged entry, we
409 * want it to be up-to-date
410 */
411static void verify_uptodate(struct cache_entry *ce)
412{
413 struct stat st;
414 if (index_only || reset)
416 return;
417 if (!lstat(ce->name, &st)) {
419 unsigned changed = ce_match_stat(ce, &st, 1);
420 if (!changed)
421 return;
422 errno = 0;
423 }
424 if (reset) {
425 ce->ce_flags |= htons(CE_UPDATE);
426 return;
427 }
428 if (errno == ENOENT)
429 return;
430 die("Entry '%s' not uptodate. Cannot merge.", ce->name);
431}
432static void invalidate_ce_path(struct cache_entry *ce)
434{
435 if (ce)
436 cache_tree_invalidate_path(active_cache_tree, ce->name);
437}
438/*
440 * We do not want to remove or overwrite a working tree file that
441 * is not tracked.
442 */
443static void verify_absent(const char *path, const char *action)
444{
445 struct stat st;
446 if (index_only || reset || !update)
448 return;
449 if (!lstat(path, &st))
450 die("Untracked working tree file '%s' "
451 "would be %s by merge.", path, action);
452}
453static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
455{
456 merge->ce_flags |= htons(CE_UPDATE);
457 if (old) {
458 /*
459 * See if we can re-use the old CE directly?
460 * That way we get the uptodate stat info.
461 *
462 * This also removes the UPDATE flag on
463 * a match.
464 */
465 if (same(old, merge)) {
466 *merge = *old;
467 } else {
468 verify_uptodate(old);
469 invalidate_ce_path(old);
470 }
471 }
472 else {
473 verify_absent(merge->name, "overwritten");
474 invalidate_ce_path(merge);
475 }
476 merge->ce_flags &= ~htons(CE_STAGEMASK);
478 add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
479 return 1;
480}
481static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
483{
484 if (old)
485 verify_uptodate(old);
486 else
487 verify_absent(ce->name, "removed");
488 ce->ce_mode = 0;
489 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
490 invalidate_ce_path(ce);
491 return 1;
492}
493static int keep_entry(struct cache_entry *ce)
495{
496 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
497 return 1;
498}
499#if DBRT_DEBUG
501static void show_stage_entry(FILE *o,
502 const char *label, const struct cache_entry *ce)
503{
504 if (!ce)
505 fprintf(o, "%s (missing)\n", label);
506 else
507 fprintf(o, "%s%06o %s %d\t%s\n",
508 label,
509 ntohl(ce->ce_mode),
510 sha1_to_hex(ce->sha1),
511 ce_stage(ce),
512 ce->name);
513}
514#endif
515static int threeway_merge(struct cache_entry **stages)
517{
518 struct cache_entry *index;
519 struct cache_entry *head;
520 struct cache_entry *remote = stages[head_idx + 1];
521 int count;
522 int head_match = 0;
523 int remote_match = 0;
524 const char *path = NULL;
525 int df_conflict_head = 0;
527 int df_conflict_remote = 0;
528 int any_anc_missing = 0;
530 int no_anc_exists = 1;
531 int i;
532 for (i = 1; i < head_idx; i++) {
534 if (!stages[i])
535 any_anc_missing = 1;
536 else {
537 if (!path)
538 path = stages[i]->name;
539 no_anc_exists = 0;
540 }
541 }
542 index = stages[0];
544 head = stages[head_idx];
545 if (head == &df_conflict_entry) {
547 df_conflict_head = 1;
548 head = NULL;
549 }
550 if (remote == &df_conflict_entry) {
552 df_conflict_remote = 1;
553 remote = NULL;
554 }
555 if (!path && index)
557 path = index->name;
558 if (!path && head)
559 path = head->name;
560 if (!path && remote)
561 path = remote->name;
562 /* First, if there's a #16 situation, note that to prevent #13
564 * and #14.
565 */
566 if (!same(remote, head)) {
567 for (i = 1; i < head_idx; i++) {
568 if (same(stages[i], head)) {
569 head_match = i;
570 }
571 if (same(stages[i], remote)) {
572 remote_match = i;
573 }
574 }
575 }
576 /* We start with cases where the index is allowed to match
578 * something other than the head: #14(ALT) and #2ALT, where it
579 * is permitted to match the result instead.
580 */
581 /* #14, #14ALT, #2ALT */
582 if (remote && !df_conflict_head && head_match && !remote_match) {
583 if (index && !same(index, remote) && !same(index, head))
584 reject_merge(index);
585 return merged_entry(remote, index);
586 }
587 /*
588 * If we have an entry in the index cache, then we want to
589 * make sure that it matches head.
590 */
591 if (index && !same(index, head)) {
592 reject_merge(index);
593 }
594 if (head) {
596 /* #5ALT, #15 */
597 if (same(head, remote))
598 return merged_entry(head, index);
599 /* #13, #3ALT */
600 if (!df_conflict_remote && remote_match && !head_match)
601 return merged_entry(head, index);
602 }
603 /* #1 */
605 if (!head && !remote && any_anc_missing)
606 return 0;
607 /* Under the new "aggressive" rule, we resolve mostly trivial
609 * cases that we historically had git-merge-one-file resolve.
610 */
611 if (aggressive) {
612 int head_deleted = !head && !df_conflict_head;
613 int remote_deleted = !remote && !df_conflict_remote;
614 /*
615 * Deleted in both.
616 * Deleted in one and unchanged in the other.
617 */
618 if ((head_deleted && remote_deleted) ||
619 (head_deleted && remote && remote_match) ||
620 (remote_deleted && head && head_match)) {
621 if (index)
622 return deleted_entry(index, index);
623 else if (path)
624 verify_absent(path, "removed");
625 return 0;
626 }
627 /*
628 * Added in both, identically.
629 */
630 if (no_anc_exists && head && remote && same(head, remote))
631 return merged_entry(head, index);
632 }
634 /* Below are "no merge" cases, which require that the index be
636 * up-to-date to avoid the files getting overwritten with
637 * conflict resolution files.
638 */
639 if (index) {
640 verify_uptodate(index);
641 }
642 else if (path)
643 verify_absent(path, "overwritten");
644 nontrivial_merge = 1;
646 /* #2, #3, #4, #6, #7, #9, #11. */
648 count = 0;
649 if (!head_match || !remote_match) {
650 for (i = 1; i < head_idx; i++) {
651 if (stages[i]) {
652 keep_entry(stages[i]);
653 count++;
654 break;
655 }
656 }
657 }
658#if DBRT_DEBUG
659 else {
660 fprintf(stderr, "read-tree: warning #16 detected\n");
661 show_stage_entry(stderr, "head ", stages[head_match]);
662 show_stage_entry(stderr, "remote ", stages[remote_match]);
663 }
664#endif
665 if (head) { count += keep_entry(head); }
666 if (remote) { count += keep_entry(remote); }
667 return count;
668}
669/*
671 * Two-way merge.
672 *
673 * The rule is to "carry forward" what is in the index without losing
674 * information across a "fast forward", favoring a successful merge
675 * over a merge failure when it makes sense. For details of the
676 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
677 *
678 */
679static int twoway_merge(struct cache_entry **src)
680{
681 struct cache_entry *current = src[0];
682 struct cache_entry *oldtree = src[1], *newtree = src[2];
683 if (merge_size != 2)
685 return error("Cannot do a twoway merge of %d trees",
686 merge_size);
687 if (current) {
689 if ((!oldtree && !newtree) || /* 4 and 5 */
690 (!oldtree && newtree &&
691 same(current, newtree)) || /* 6 and 7 */
692 (oldtree && newtree &&
693 same(oldtree, newtree)) || /* 14 and 15 */
694 (oldtree && newtree &&
695 !same(oldtree, newtree) && /* 18 and 19*/
696 same(current, newtree))) {
697 return keep_entry(current);
698 }
699 else if (oldtree && !newtree && same(current, oldtree)) {
700 /* 10 or 11 */
701 return deleted_entry(oldtree, current);
702 }
703 else if (oldtree && newtree &&
704 same(current, oldtree) && !same(current, newtree)) {
705 /* 20 or 21 */
706 return merged_entry(newtree, current);
707 }
708 else {
709 /* all other failures */
710 if (oldtree)
711 reject_merge(oldtree);
712 if (current)
713 reject_merge(current);
714 if (newtree)
715 reject_merge(newtree);
716 return -1;
717 }
718 }
719 else if (newtree)
720 return merged_entry(newtree, current);
721 else
722 return deleted_entry(oldtree, current);
723}
724/*
726 * One-way merge.
727 *
728 * The rule is:
729 * - take the stat information from stage0, take the data from stage1
730 */
731static int oneway_merge(struct cache_entry **src)
732{
733 struct cache_entry *old = src[0];
734 struct cache_entry *a = src[1];
735 if (merge_size != 1)
737 return error("Cannot do a oneway merge of %d trees",
738 merge_size);
739 if (!a)
741 return deleted_entry(old, old);
742 if (old && same(old, a)) {
743 if (reset) {
744 struct stat st;
745 if (lstat(old->name, &st) ||
746 ce_match_stat(old, &st, 1))
747 old->ce_flags |= htons(CE_UPDATE);
748 }
749 return keep_entry(old);
750 }
751 return merged_entry(a, old);
752}
753static int read_cache_unmerged(void)
755{
756 int i, deleted;
757 struct cache_entry **dst;
758 read_cache();
760 dst = active_cache;
761 deleted = 0;
762 for (i = 0; i < active_nr; i++) {
763 struct cache_entry *ce = active_cache[i];
764 if (ce_stage(ce)) {
765 deleted++;
766 invalidate_ce_path(ce);
767 continue;
768 }
769 if (deleted)
770 *dst = ce;
771 dst++;
772 }
773 active_nr -= deleted;
774 return deleted;
775}
776static void prime_cache_tree_rec(struct cache_tree *it, struct tree *tree)
778{
779 struct tree_desc desc;
780 int cnt;
781 memcpy(it->sha1, tree->object.sha1, 20);
783 desc.buf = tree->buffer;
784 desc.size = tree->size;
785 cnt = 0;
786 while (desc.size) {
787 unsigned mode;
788 const char *name;
789 const unsigned char *sha1;
790 sha1 = tree_entry_extract(&desc, &name, &mode);
792 update_tree_entry(&desc);
793 if (!S_ISDIR(mode))
794 cnt++;
795 else {
796 struct cache_tree_sub *sub;
797 struct tree *subtree = lookup_tree(sha1);
798 if (!subtree->object.parsed)
799 parse_tree(subtree);
800 sub = cache_tree_sub(it, name);
801 sub->cache_tree = cache_tree();
802 prime_cache_tree_rec(sub->cache_tree, subtree);
803 cnt += sub->cache_tree->entry_count;
804 }
805 }
806 it->entry_count = cnt;
807}
808static void prime_cache_tree(void)
810{
811 struct tree *tree = (struct tree *)trees->item;
812 if (!tree)
813 return;
814 active_cache_tree = cache_tree();
815 prime_cache_tree_rec(active_cache_tree, tree);
816}
818static const char read_tree_usage[] = "git-read-tree (<sha> | -m [--aggressive] [-u | -i] <sha1> [<sha2> [<sha3>]])";
820static struct cache_file cache_file;
822int cmd_read_tree(int argc, const char **argv, char **envp)
824{
825 int i, newfd, stage = 0;
826 unsigned char sha1[20];
827 merge_fn_t fn = NULL;
828 setup_git_directory();
830 git_config(git_default_config);
831 newfd = hold_index_file_for_update(&cache_file, get_index_file());
833 if (newfd < 0)
834 die("unable to create new cachefile");
835 git_config(git_default_config);
837 merge = 0;
839 reset = 0;
840 for (i = 1; i < argc; i++) {
841 const char *arg = argv[i];
842 /* "-u" means "update", meaning that a merge will update
844 * the working tree.
845 */
846 if (!strcmp(arg, "-u")) {
847 update = 1;
848 continue;
849 }
850 if (!strcmp(arg, "-v")) {
852 verbose_update = 1;
853 continue;
854 }
855 /* "-i" means "index only", meaning that a merge will
857 * not even look at the working tree.
858 */
859 if (!strcmp(arg, "-i")) {
860 index_only = 1;
861 continue;
862 }
863 /* This differs from "-m" in that we'll silently ignore unmerged entries */
865 if (!strcmp(arg, "--reset")) {
866 if (stage || merge)
867 usage(read_tree_usage);
868 reset = 1;
869 merge = 1;
870 stage = 1;
871 read_cache_unmerged();
872 continue;
873 }
874 if (!strcmp(arg, "--trivial")) {
876 trivial_merges_only = 1;
877 continue;
878 }
879 if (!strcmp(arg, "--aggressive")) {
881 aggressive = 1;
882 continue;
883 }
884 /* "-m" stands for "merge", meaning we start in stage 1 */
886 if (!strcmp(arg, "-m")) {
887 if (stage || merge)
888 usage(read_tree_usage);
889 if (read_cache_unmerged())
890 die("you need to resolve your current index first");
891 stage = 1;
892 merge = 1;
893 continue;
894 }
895 /* using -u and -i at the same time makes no sense */
897 if (1 < index_only + update)
898 usage(read_tree_usage);
899 if (get_sha1(arg, sha1))
901 die("Not a valid object name %s", arg);
902 if (list_tree(sha1) < 0)
903 die("failed to unpack tree object %s", arg);
904 stage++;
905 }
906 if ((update||index_only) && !merge)
907 usage(read_tree_usage);
908 if (merge) {
910 if (stage < 2)
911 die("just how do you expect me to merge %d trees?", stage-1);
912 switch (stage - 1) {
913 case 1:
914 fn = oneway_merge;
915 break;
916 case 2:
917 fn = twoway_merge;
918 break;
919 case 3:
920 default:
921 fn = threeway_merge;
922 cache_tree_free(&active_cache_tree);
923 break;
924 }
925 if (stage - 1 >= 3)
927 head_idx = stage - 2;
928 else
929 head_idx = 1;
930 }
931 unpack_trees(fn);
933 /*
935 * When reading only one tree (either the most basic form,
936 * "-m ent" or "--reset ent" form), we can obtain a fully
937 * valid cache-tree because the index must match exactly
938 * what came from the tree.
939 */
940 if (trees && trees->item && (!merge || (stage == 2))) {
941 cache_tree_free(&active_cache_tree);
942 prime_cache_tree();
943 }
944 if (write_cache(newfd, active_cache, active_nr) ||
946 commit_index_file(&cache_file))
947 die("unable to write new index file");
948 return 0;
949}