read-tree -u one-way merge fix to check out locally modified paths.
[git] / read-tree.c
1 /*
2  * GIT - The information manager from hell
3  *
4  * Copyright (C) Linus Torvalds, 2005
5  */
6 #define DBRT_DEBUG 1
7
8 #include "cache.h"
9
10 #include "object.h"
11 #include "tree.h"
12 #include <sys/time.h>
13 #include <signal.h>
14
15 static int merge = 0;
16 static int update = 0;
17 static int index_only = 0;
18 static int nontrivial_merge = 0;
19 static int trivial_merges_only = 0;
20 static int aggressive = 0;
21 static int verbose_update = 0;
22 static volatile int progress_update = 0;
23
24 static int head_idx = -1;
25 static int merge_size = 0;
26
27 static struct object_list *trees = NULL;
28
29 static struct cache_entry df_conflict_entry = { 
30 };
31
32 static struct tree_entry_list df_conflict_list = {
33         .name = NULL,
34         .next = &df_conflict_list
35 };
36
37 typedef int (*merge_fn_t)(struct cache_entry **src);
38
39 static int entcmp(char *name1, int dir1, char *name2, int dir2)
40 {
41         int len1 = strlen(name1);
42         int len2 = strlen(name2);
43         int len = len1 < len2 ? len1 : len2;
44         int ret = memcmp(name1, name2, len);
45         unsigned char c1, c2;
46         if (ret)
47                 return ret;
48         c1 = name1[len];
49         c2 = name2[len];
50         if (!c1 && dir1)
51                 c1 = '/';
52         if (!c2 && dir2)
53                 c2 = '/';
54         ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
55         if (c1 && c2 && !ret)
56                 ret = len1 - len2;
57         return ret;
58 }
59
60 static int unpack_trees_rec(struct tree_entry_list **posns, int len,
61                             const char *base, merge_fn_t fn, int *indpos)
62 {
63         int baselen = strlen(base);
64         int src_size = len + 1;
65         do {
66                 int i;
67                 char *first;
68                 int firstdir = 0;
69                 int pathlen;
70                 unsigned ce_size;
71                 struct tree_entry_list **subposns;
72                 struct cache_entry **src;
73                 int any_files = 0;
74                 int any_dirs = 0;
75                 char *cache_name;
76                 int ce_stage;
77
78                 /* Find the first name in the input. */
79
80                 first = NULL;
81                 cache_name = NULL;
82
83                 /* Check the cache */
84                 if (merge && *indpos < active_nr) {
85                         /* This is a bit tricky: */
86                         /* If the index has a subdirectory (with
87                          * contents) as the first name, it'll get a
88                          * filename like "foo/bar". But that's after
89                          * "foo", so the entry in trees will get
90                          * handled first, at which point we'll go into
91                          * "foo", and deal with "bar" from the index,
92                          * because the base will be "foo/". The only
93                          * way we can actually have "foo/bar" first of
94                          * all the things is if the trees don't
95                          * contain "foo" at all, in which case we'll
96                          * handle "foo/bar" without going into the
97                          * directory, but that's fine (and will return
98                          * an error anyway, with the added unknown
99                          * file case.
100                          */
101
102                         cache_name = active_cache[*indpos]->name;
103                         if (strlen(cache_name) > baselen &&
104                             !memcmp(cache_name, base, baselen)) {
105                                 cache_name += baselen;
106                                 first = cache_name;
107                         } else {
108                                 cache_name = NULL;
109                         }
110                 }
111
112 #if DBRT_DEBUG > 1
113                 if (first)
114                         printf("index %s\n", first);
115 #endif
116                 for (i = 0; i < len; i++) {
117                         if (!posns[i] || posns[i] == &df_conflict_list)
118                                 continue;
119 #if DBRT_DEBUG > 1
120                         printf("%d %s\n", i + 1, posns[i]->name);
121 #endif
122                         if (!first || entcmp(first, firstdir,
123                                              posns[i]->name, 
124                                              posns[i]->directory) > 0) {
125                                 first = posns[i]->name;
126                                 firstdir = posns[i]->directory;
127                         }
128                 }
129                 /* No name means we're done */
130                 if (!first)
131                         return 0;
132
133                 pathlen = strlen(first);
134                 ce_size = cache_entry_size(baselen + pathlen);
135
136                 src = xcalloc(src_size, sizeof(struct cache_entry *));
137
138                 subposns = xcalloc(len, sizeof(struct tree_list_entry *));
139
140                 if (cache_name && !strcmp(cache_name, first)) {
141                         any_files = 1;
142                         src[0] = active_cache[*indpos];
143                         remove_cache_entry_at(*indpos);
144                 }
145
146                 for (i = 0; i < len; i++) {
147                         struct cache_entry *ce;
148
149                         if (!posns[i] ||
150                             (posns[i] != &df_conflict_list &&
151                              strcmp(first, posns[i]->name))) {
152                                 continue;
153                         }
154
155                         if (posns[i] == &df_conflict_list) {
156                                 src[i + merge] = &df_conflict_entry;
157                                 continue;
158                         }
159
160                         if (posns[i]->directory) {
161                                 any_dirs = 1;
162                                 parse_tree(posns[i]->item.tree);
163                                 subposns[i] = posns[i]->item.tree->entries;
164                                 posns[i] = posns[i]->next;
165                                 src[i + merge] = &df_conflict_entry;
166                                 continue;
167                         }
168
169                         if (!merge)
170                                 ce_stage = 0;
171                         else if (i + 1 < head_idx)
172                                 ce_stage = 1;
173                         else if (i + 1 > head_idx)
174                                 ce_stage = 3;
175                         else
176                                 ce_stage = 2;
177
178                         ce = xcalloc(1, ce_size);
179                         ce->ce_mode = create_ce_mode(posns[i]->mode);
180                         ce->ce_flags = create_ce_flags(baselen + pathlen,
181                                                        ce_stage);
182                         memcpy(ce->name, base, baselen);
183                         memcpy(ce->name + baselen, first, pathlen + 1);
184
185                         any_files = 1;
186
187                         memcpy(ce->sha1, posns[i]->item.any->sha1, 20);
188                         src[i + merge] = ce;
189                         subposns[i] = &df_conflict_list;
190                         posns[i] = posns[i]->next;
191                 }
192                 if (any_files) {
193                         if (merge) {
194                                 int ret;
195
196 #if DBRT_DEBUG > 1
197                                 printf("%s:\n", first);
198                                 for (i = 0; i < src_size; i++) {
199                                         printf(" %d ", i);
200                                         if (src[i])
201                                                 printf("%s\n", sha1_to_hex(src[i]->sha1));
202                                         else
203                                                 printf("\n");
204                                 }
205 #endif
206                                 ret = fn(src);
207                                 
208 #if DBRT_DEBUG > 1
209                                 printf("Added %d entries\n", ret);
210 #endif
211                                 *indpos += ret;
212                         } else {
213                                 for (i = 0; i < src_size; i++) {
214                                         if (src[i]) {
215                                                 add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
216                                         }
217                                 }
218                         }
219                 }
220                 if (any_dirs) {
221                         char *newbase = xmalloc(baselen + 2 + pathlen);
222                         memcpy(newbase, base, baselen);
223                         memcpy(newbase + baselen, first, pathlen);
224                         newbase[baselen + pathlen] = '/';
225                         newbase[baselen + pathlen + 1] = '\0';
226                         if (unpack_trees_rec(subposns, len, newbase, fn,
227                                              indpos))
228                                 return -1;
229                         free(newbase);
230                 }
231                 free(subposns);
232                 free(src);
233         } while (1);
234 }
235
236 static void reject_merge(struct cache_entry *ce)
237 {
238         die("Entry '%s' would be overwritten by merge. Cannot merge.", 
239             ce->name);
240 }
241
242 /* Unlink the last component and attempt to remove leading
243  * directories, in case this unlink is the removal of the
244  * last entry in the directory -- empty directories are removed.
245  */
246 static void unlink_entry(char *name)
247 {
248         char *cp, *prev;
249
250         if (unlink(name))
251                 return;
252         prev = NULL;
253         while (1) {
254                 int status;
255                 cp = strrchr(name, '/');
256                 if (prev)
257                         *prev = '/';
258                 if (!cp)
259                         break;
260
261                 *cp = 0;
262                 status = rmdir(name);
263                 if (status) {
264                         *cp = '/';
265                         break;
266                 }
267                 prev = cp;
268         }
269 }
270
271 static void progress_interval(int signum)
272 {
273         progress_update = 1;
274 }
275
276 static void setup_progress_signal(void)
277 {
278         struct sigaction sa;
279         struct itimerval v;
280
281         memset(&sa, 0, sizeof(sa));
282         sa.sa_handler = progress_interval;
283         sigemptyset(&sa.sa_mask);
284         sa.sa_flags = SA_RESTART;
285         sigaction(SIGALRM, &sa, NULL);
286
287         v.it_interval.tv_sec = 1;
288         v.it_interval.tv_usec = 0;
289         v.it_value = v.it_interval;
290         setitimer(ITIMER_REAL, &v, NULL);
291 }
292
293 static void check_updates(struct cache_entry **src, int nr)
294 {
295         static struct checkout state = {
296                 .base_dir = "",
297                 .force = 1,
298                 .quiet = 1,
299                 .refresh_cache = 1,
300         };
301         unsigned short mask = htons(CE_UPDATE);
302         unsigned last_percent = 200, cnt = 0, total = 0;
303
304         if (update && verbose_update) {
305                 for (total = cnt = 0; cnt < nr; cnt++) {
306                         struct cache_entry *ce = src[cnt];
307                         if (!ce->ce_mode || ce->ce_flags & mask)
308                                 total++;
309                 }
310
311                 /* Don't bother doing this for very small updates */
312                 if (total < 250)
313                         total = 0;
314
315                 if (total) {
316                         fprintf(stderr, "Checking files out...\n");
317                         setup_progress_signal();
318                         progress_update = 1;
319                 }
320                 cnt = 0;
321         }
322
323         while (nr--) {
324                 struct cache_entry *ce = *src++;
325
326                 if (total) {
327                         if (!ce->ce_mode || ce->ce_flags & mask) {
328                                 unsigned percent;
329                                 cnt++;
330                                 percent = (cnt * 100) / total;
331                                 if (percent != last_percent ||
332                                     progress_update) {
333                                         fprintf(stderr, "%4u%% (%u/%u) done\r",
334                                                 percent, cnt, total);
335                                         last_percent = percent;
336                                 }
337                         }
338                 }
339                 if (!ce->ce_mode) {
340                         if (update)
341                                 unlink_entry(ce->name);
342                         continue;
343                 }
344                 if (ce->ce_flags & mask) {
345                         ce->ce_flags &= ~mask;
346                         if (update)
347                                 checkout_entry(ce, &state, NULL);
348                 }
349         }
350         if (total) {
351                 signal(SIGALRM, SIG_IGN);
352                 fputc('\n', stderr);
353         }
354 }
355
356 static int unpack_trees(merge_fn_t fn)
357 {
358         int indpos = 0;
359         unsigned len = object_list_length(trees);
360         struct tree_entry_list **posns;
361         int i;
362         struct object_list *posn = trees;
363         merge_size = len;
364
365         if (len) {
366                 posns = xmalloc(len * sizeof(struct tree_entry_list *));
367                 for (i = 0; i < len; i++) {
368                         posns[i] = ((struct tree *) posn->item)->entries;
369                         posn = posn->next;
370                 }
371                 if (unpack_trees_rec(posns, len, "", fn, &indpos))
372                         return -1;
373         }
374
375         if (trivial_merges_only && nontrivial_merge)
376                 die("Merge requires file-level merging");
377
378         check_updates(active_cache, active_nr);
379         return 0;
380 }
381
382 static int list_tree(unsigned char *sha1)
383 {
384         struct tree *tree = parse_tree_indirect(sha1);
385         if (!tree)
386                 return -1;
387         object_list_append(&tree->object, &trees);
388         return 0;
389 }
390
391 static int same(struct cache_entry *a, struct cache_entry *b)
392 {
393         if (!!a != !!b)
394                 return 0;
395         if (!a && !b)
396                 return 1;
397         return a->ce_mode == b->ce_mode && 
398                 !memcmp(a->sha1, b->sha1, 20);
399 }
400
401
402 /*
403  * When a CE gets turned into an unmerged entry, we
404  * want it to be up-to-date
405  */
406 static void verify_uptodate(struct cache_entry *ce)
407 {
408         struct stat st;
409
410         if (index_only)
411                 return;
412
413         if (!lstat(ce->name, &st)) {
414                 unsigned changed = ce_match_stat(ce, &st, 1);
415                 if (!changed)
416                         return;
417                 errno = 0;
418         }
419         if (errno == ENOENT)
420                 return;
421         die("Entry '%s' not uptodate. Cannot merge.", ce->name);
422 }
423
424 static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
425 {
426         merge->ce_flags |= htons(CE_UPDATE);
427         if (old) {
428                 /*
429                  * See if we can re-use the old CE directly?
430                  * That way we get the uptodate stat info.
431                  *
432                  * This also removes the UPDATE flag on
433                  * a match.
434                  */
435                 if (same(old, merge)) {
436                         *merge = *old;
437                 } else {
438                         verify_uptodate(old);
439                 }
440         }
441         merge->ce_flags &= ~htons(CE_STAGEMASK);
442         add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
443         return 1;
444 }
445
446 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
447 {
448         if (old)
449                 verify_uptodate(old);
450         ce->ce_mode = 0;
451         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
452         return 1;
453 }
454
455 static int keep_entry(struct cache_entry *ce)
456 {
457         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
458         return 1;
459 }
460
461 #if DBRT_DEBUG
462 static void show_stage_entry(FILE *o,
463                              const char *label, const struct cache_entry *ce)
464 {
465         if (!ce)
466                 fprintf(o, "%s (missing)\n", label);
467         else
468                 fprintf(o, "%s%06o %s %d\t%s\n",
469                         label,
470                         ntohl(ce->ce_mode),
471                         sha1_to_hex(ce->sha1),
472                         ce_stage(ce),
473                         ce->name);
474 }
475 #endif
476
477 static int threeway_merge(struct cache_entry **stages)
478 {
479         struct cache_entry *index;
480         struct cache_entry *head; 
481         struct cache_entry *remote = stages[head_idx + 1];
482         int count;
483         int head_match = 0;
484         int remote_match = 0;
485
486         int df_conflict_head = 0;
487         int df_conflict_remote = 0;
488
489         int any_anc_missing = 0;
490         int no_anc_exists = 1;
491         int i;
492
493         for (i = 1; i < head_idx; i++) {
494                 if (!stages[i])
495                         any_anc_missing = 1;
496                 else
497                         no_anc_exists = 0;
498         }
499
500         index = stages[0];
501         head = stages[head_idx];
502
503         if (head == &df_conflict_entry) {
504                 df_conflict_head = 1;
505                 head = NULL;
506         }
507
508         if (remote == &df_conflict_entry) {
509                 df_conflict_remote = 1;
510                 remote = NULL;
511         }
512
513         /* First, if there's a #16 situation, note that to prevent #13
514          * and #14. 
515          */
516         if (!same(remote, head)) {
517                 for (i = 1; i < head_idx; i++) {
518                         if (same(stages[i], head)) {
519                                 head_match = i;
520                         }
521                         if (same(stages[i], remote)) {
522                                 remote_match = i;
523                         }
524                 }
525         }
526
527         /* We start with cases where the index is allowed to match
528          * something other than the head: #14(ALT) and #2ALT, where it
529          * is permitted to match the result instead.
530          */
531         /* #14, #14ALT, #2ALT */
532         if (remote && !df_conflict_head && head_match && !remote_match) {
533                 if (index && !same(index, remote) && !same(index, head))
534                         reject_merge(index);
535                 return merged_entry(remote, index);
536         }
537         /*
538          * If we have an entry in the index cache, then we want to
539          * make sure that it matches head.
540          */
541         if (index && !same(index, head)) {
542                 reject_merge(index);
543         }
544
545         if (head) {
546                 /* #5ALT, #15 */
547                 if (same(head, remote))
548                         return merged_entry(head, index);
549                 /* #13, #3ALT */
550                 if (!df_conflict_remote && remote_match && !head_match)
551                         return merged_entry(head, index);
552         }
553
554         /* #1 */
555         if (!head && !remote && any_anc_missing)
556                 return 0;
557
558         /* Under the new "aggressive" rule, we resolve mostly trivial
559          * cases that we historically had git-merge-one-file resolve.
560          */
561         if (aggressive) {
562                 int head_deleted = !head && !df_conflict_head;
563                 int remote_deleted = !remote && !df_conflict_remote;
564                 /*
565                  * Deleted in both.
566                  * Deleted in one and unchanged in the other.
567                  */
568                 if ((head_deleted && remote_deleted) ||
569                     (head_deleted && remote && remote_match) ||
570                     (remote_deleted && head && head_match)) {
571                         if (index)
572                                 return deleted_entry(index, index);
573                         return 0;
574                 }
575                 /*
576                  * Added in both, identically.
577                  */
578                 if (no_anc_exists && head && remote && same(head, remote))
579                         return merged_entry(head, index);
580
581         }
582
583         /* Below are "no merge" cases, which require that the index be
584          * up-to-date to avoid the files getting overwritten with
585          * conflict resolution files. 
586          */
587         if (index) {
588                 verify_uptodate(index);
589         }
590
591         nontrivial_merge = 1;
592
593         /* #2, #3, #4, #6, #7, #9, #11. */
594         count = 0;
595         if (!head_match || !remote_match) {
596                 for (i = 1; i < head_idx; i++) {
597                         if (stages[i]) {
598                                 keep_entry(stages[i]);
599                                 count++;
600                                 break;
601                         }
602                 }
603         }
604 #if DBRT_DEBUG
605         else {
606                 fprintf(stderr, "read-tree: warning #16 detected\n");
607                 show_stage_entry(stderr, "head   ", stages[head_match]);
608                 show_stage_entry(stderr, "remote ", stages[remote_match]);
609         }
610 #endif
611         if (head) { count += keep_entry(head); }
612         if (remote) { count += keep_entry(remote); }
613         return count;
614 }
615
616 /*
617  * Two-way merge.
618  *
619  * The rule is to "carry forward" what is in the index without losing
620  * information across a "fast forward", favoring a successful merge
621  * over a merge failure when it makes sense.  For details of the
622  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
623  *
624  */
625 static int twoway_merge(struct cache_entry **src)
626 {
627         struct cache_entry *current = src[0];
628         struct cache_entry *oldtree = src[1], *newtree = src[2];
629
630         if (merge_size != 2)
631                 return error("Cannot do a twoway merge of %d trees",
632                              merge_size);
633
634         if (current) {
635                 if ((!oldtree && !newtree) || /* 4 and 5 */
636                     (!oldtree && newtree &&
637                      same(current, newtree)) || /* 6 and 7 */
638                     (oldtree && newtree &&
639                      same(oldtree, newtree)) || /* 14 and 15 */
640                     (oldtree && newtree &&
641                      !same(oldtree, newtree) && /* 18 and 19*/
642                      same(current, newtree))) {
643                         return keep_entry(current);
644                 }
645                 else if (oldtree && !newtree && same(current, oldtree)) {
646                         /* 10 or 11 */
647                         return deleted_entry(oldtree, current);
648                 }
649                 else if (oldtree && newtree &&
650                          same(current, oldtree) && !same(current, newtree)) {
651                         /* 20 or 21 */
652                         return merged_entry(newtree, current);
653                 }
654                 else {
655                         /* all other failures */
656                         if (oldtree)
657                                 reject_merge(oldtree);
658                         if (current)
659                                 reject_merge(current);
660                         if (newtree)
661                                 reject_merge(newtree);
662                         return -1;
663                 }
664         }
665         else if (newtree)
666                 return merged_entry(newtree, current);
667         else
668                 return deleted_entry(oldtree, current);
669 }
670
671 /*
672  * One-way merge.
673  *
674  * The rule is:
675  * - take the stat information from stage0, take the data from stage1
676  */
677 static int oneway_merge(struct cache_entry **src)
678 {
679         struct cache_entry *old = src[0];
680         struct cache_entry *a = src[1];
681
682         if (merge_size != 1)
683                 return error("Cannot do a oneway merge of %d trees",
684                              merge_size);
685
686         if (!a)
687                 return deleted_entry(old, NULL);
688         if (old && same(old, a)) {
689                 struct stat st;
690                 if (lstat(old->name, &st) || ce_match_stat(old, &st, 1))
691                         old->ce_flags |= htons(CE_UPDATE);
692                 return keep_entry(old);
693         }
694         return merged_entry(a, NULL);
695 }
696
697 static int read_cache_unmerged(void)
698 {
699         int i, deleted;
700         struct cache_entry **dst;
701
702         read_cache();
703         dst = active_cache;
704         deleted = 0;
705         for (i = 0; i < active_nr; i++) {
706                 struct cache_entry *ce = active_cache[i];
707                 if (ce_stage(ce)) {
708                         deleted++;
709                         continue;
710                 }
711                 if (deleted)
712                         *dst = ce;
713                 dst++;
714         }
715         active_nr -= deleted;
716         return deleted;
717 }
718
719 static const char read_tree_usage[] = "git-read-tree (<sha> | -m [--aggressive] [-u | -i] <sha1> [<sha2> [<sha3>]])";
720
721 static struct cache_file cache_file;
722
723 int main(int argc, char **argv)
724 {
725         int i, newfd, reset, stage = 0;
726         unsigned char sha1[20];
727         merge_fn_t fn = NULL;
728
729         setup_git_directory();
730         git_config(git_default_config);
731
732         newfd = hold_index_file_for_update(&cache_file, get_index_file());
733         if (newfd < 0)
734                 die("unable to create new cachefile");
735
736         git_config(git_default_config);
737
738         merge = 0;
739         reset = 0;
740         for (i = 1; i < argc; i++) {
741                 const char *arg = argv[i];
742
743                 /* "-u" means "update", meaning that a merge will update
744                  * the working tree.
745                  */
746                 if (!strcmp(arg, "-u")) {
747                         update = 1;
748                         continue;
749                 }
750
751                 if (!strcmp(arg, "-v")) {
752                         verbose_update = 1;
753                         continue;
754                 }
755
756                 /* "-i" means "index only", meaning that a merge will
757                  * not even look at the working tree.
758                  */
759                 if (!strcmp(arg, "-i")) {
760                         index_only = 1;
761                         continue;
762                 }
763
764                 /* This differs from "-m" in that we'll silently ignore unmerged entries */
765                 if (!strcmp(arg, "--reset")) {
766                         if (stage || merge)
767                                 usage(read_tree_usage);
768                         reset = 1;
769                         merge = 1;
770                         stage = 1;
771                         read_cache_unmerged();
772                         continue;
773                 }
774
775                 if (!strcmp(arg, "--trivial")) {
776                         trivial_merges_only = 1;
777                         continue;
778                 }
779
780                 if (!strcmp(arg, "--aggressive")) {
781                         aggressive = 1;
782                         continue;
783                 }
784
785                 /* "-m" stands for "merge", meaning we start in stage 1 */
786                 if (!strcmp(arg, "-m")) {
787                         if (stage || merge)
788                                 usage(read_tree_usage);
789                         if (read_cache_unmerged())
790                                 die("you need to resolve your current index first");
791                         stage = 1;
792                         merge = 1;
793                         continue;
794                 }
795
796                 /* using -u and -i at the same time makes no sense */
797                 if (1 < index_only + update)
798                         usage(read_tree_usage);
799
800                 if (get_sha1(arg, sha1))
801                         die("Not a valid object name %s", arg);
802                 if (list_tree(sha1) < 0)
803                         die("failed to unpack tree object %s", arg);
804                 stage++;
805         }
806         if ((update||index_only) && !merge)
807                 usage(read_tree_usage);
808
809         if (merge) {
810                 if (stage < 2)
811                         die("just how do you expect me to merge %d trees?", stage-1);
812                 switch (stage - 1) {
813                 case 1:
814                         fn = oneway_merge;
815                         break;
816                 case 2:
817                         fn = twoway_merge;
818                         break;
819                 case 3:
820                         fn = threeway_merge;
821                         break;
822                 default:
823                         fn = threeway_merge;
824                         break;
825                 }
826
827                 if (stage - 1 >= 3)
828                         head_idx = stage - 2;
829                 else
830                         head_idx = 1;
831         }
832
833         unpack_trees(fn);
834         if (write_cache(newfd, active_cache, active_nr) ||
835             commit_index_file(&cache_file))
836                 die("unable to write new index file");
837         return 0;
838 }