unpack_trees(): fix diff-index regression.
[git] / diff-lib.c
1 /*
2  * Copyright (C) 2005 Junio C Hamano
3  */
4 #include "cache.h"
5 #include "quote.h"
6 #include "commit.h"
7 #include "diff.h"
8 #include "diffcore.h"
9 #include "revision.h"
10 #include "cache-tree.h"
11 #include "path-list.h"
12 #include "unpack-trees.h"
13
14 /*
15  * diff-files
16  */
17
18 static int read_directory(const char *path, struct path_list *list)
19 {
20         DIR *dir;
21         struct dirent *e;
22
23         if (!(dir = opendir(path)))
24                 return error("Could not open directory %s", path);
25
26         while ((e = readdir(dir)))
27                 if (strcmp(".", e->d_name) && strcmp("..", e->d_name))
28                         path_list_insert(e->d_name, list);
29
30         closedir(dir);
31         return 0;
32 }
33
34 static int get_mode(const char *path, int *mode)
35 {
36         struct stat st;
37
38         if (!path || !strcmp(path, "/dev/null"))
39                 *mode = 0;
40         else if (!strcmp(path, "-"))
41                 *mode = create_ce_mode(0666);
42         else if (stat(path, &st))
43                 return error("Could not access '%s'", path);
44         else
45                 *mode = st.st_mode;
46         return 0;
47 }
48
49 static int queue_diff(struct diff_options *o,
50                 const char *name1, const char *name2)
51 {
52         int mode1 = 0, mode2 = 0;
53
54         if (get_mode(name1, &mode1) || get_mode(name2, &mode2))
55                 return -1;
56
57         if (mode1 && mode2 && S_ISDIR(mode1) != S_ISDIR(mode2))
58                 return error("file/directory conflict: %s, %s", name1, name2);
59
60         if (S_ISDIR(mode1) || S_ISDIR(mode2)) {
61                 char buffer1[PATH_MAX], buffer2[PATH_MAX];
62                 struct path_list p1 = {NULL, 0, 0, 1}, p2 = {NULL, 0, 0, 1};
63                 int len1 = 0, len2 = 0, i1, i2, ret = 0;
64
65                 if (name1 && read_directory(name1, &p1))
66                         return -1;
67                 if (name2 && read_directory(name2, &p2)) {
68                         path_list_clear(&p1, 0);
69                         return -1;
70                 }
71
72                 if (name1) {
73                         len1 = strlen(name1);
74                         if (len1 > 0 && name1[len1 - 1] == '/')
75                                 len1--;
76                         memcpy(buffer1, name1, len1);
77                         buffer1[len1++] = '/';
78                 }
79
80                 if (name2) {
81                         len2 = strlen(name2);
82                         if (len2 > 0 && name2[len2 - 1] == '/')
83                                 len2--;
84                         memcpy(buffer2, name2, len2);
85                         buffer2[len2++] = '/';
86                 }
87
88                 for (i1 = i2 = 0; !ret && (i1 < p1.nr || i2 < p2.nr); ) {
89                         const char *n1, *n2;
90                         int comp;
91
92                         if (i1 == p1.nr)
93                                 comp = 1;
94                         else if (i2 == p2.nr)
95                                 comp = -1;
96                         else
97                                 comp = strcmp(p1.items[i1].path,
98                                         p2.items[i2].path);
99
100                         if (comp > 0)
101                                 n1 = NULL;
102                         else {
103                                 n1 = buffer1;
104                                 strncpy(buffer1 + len1, p1.items[i1++].path,
105                                                 PATH_MAX - len1);
106                         }
107
108                         if (comp < 0)
109                                 n2 = NULL;
110                         else {
111                                 n2 = buffer2;
112                                 strncpy(buffer2 + len2, p2.items[i2++].path,
113                                                 PATH_MAX - len2);
114                         }
115
116                         ret = queue_diff(o, n1, n2);
117                 }
118                 path_list_clear(&p1, 0);
119                 path_list_clear(&p2, 0);
120
121                 return ret;
122         } else {
123                 struct diff_filespec *d1, *d2;
124
125                 if (DIFF_OPT_TST(o, REVERSE_DIFF)) {
126                         unsigned tmp;
127                         const char *tmp_c;
128                         tmp = mode1; mode1 = mode2; mode2 = tmp;
129                         tmp_c = name1; name1 = name2; name2 = tmp_c;
130                 }
131
132                 if (!name1)
133                         name1 = "/dev/null";
134                 if (!name2)
135                         name2 = "/dev/null";
136                 d1 = alloc_filespec(name1);
137                 d2 = alloc_filespec(name2);
138                 fill_filespec(d1, null_sha1, mode1);
139                 fill_filespec(d2, null_sha1, mode2);
140
141                 diff_queue(&diff_queued_diff, d1, d2);
142                 return 0;
143         }
144 }
145
146 /*
147  * Does the path name a blob in the working tree, or a directory
148  * in the working tree?
149  */
150 static int is_in_index(const char *path)
151 {
152         int len, pos;
153         struct cache_entry *ce;
154
155         len = strlen(path);
156         while (path[len-1] == '/')
157                 len--;
158         if (!len)
159                 return 1; /* "." */
160         pos = cache_name_pos(path, len);
161         if (0 <= pos)
162                 return 1;
163         pos = -1 - pos;
164         while (pos < active_nr) {
165                 ce = active_cache[pos++];
166                 if (ce_namelen(ce) <= len ||
167                     strncmp(ce->name, path, len) ||
168                     (ce->name[len] > '/'))
169                         break; /* path cannot be a prefix */
170                 if (ce->name[len] == '/')
171                         return 1;
172         }
173         return 0;
174 }
175
176 static int handle_diff_files_args(struct rev_info *revs,
177                                   int argc, const char **argv,
178                                   unsigned int *options)
179 {
180         *options = 0;
181
182         /* revs->max_count == -2 means --no-index */
183         while (1 < argc && argv[1][0] == '-') {
184                 if (!strcmp(argv[1], "--base"))
185                         revs->max_count = 1;
186                 else if (!strcmp(argv[1], "--ours"))
187                         revs->max_count = 2;
188                 else if (!strcmp(argv[1], "--theirs"))
189                         revs->max_count = 3;
190                 else if (!strcmp(argv[1], "-n") ||
191                                 !strcmp(argv[1], "--no-index")) {
192                         revs->max_count = -2;
193                         DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS);
194                         DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
195                 }
196                 else if (!strcmp(argv[1], "-q"))
197                         *options |= DIFF_SILENT_ON_REMOVED;
198                 else
199                         return error("invalid option: %s", argv[1]);
200                 argv++; argc--;
201         }
202
203         if (revs->max_count == -1 && revs->diffopt.nr_paths == 2) {
204                 /*
205                  * If two files are specified, and at least one is untracked,
206                  * default to no-index.
207                  */
208                 read_cache();
209                 if (!is_in_index(revs->diffopt.paths[0]) ||
210                                         !is_in_index(revs->diffopt.paths[1])) {
211                         revs->max_count = -2;
212                         DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
213                 }
214         }
215
216         /*
217          * Make sure there are NO revision (i.e. pending object) parameter,
218          * rev.max_count is reasonable (0 <= n <= 3),
219          * there is no other revision filtering parameters.
220          */
221         if (revs->pending.nr || revs->max_count > 3 ||
222             revs->min_age != -1 || revs->max_age != -1)
223                 return error("no revision allowed with diff-files");
224
225         if (revs->max_count == -1 &&
226             (revs->diffopt.output_format & DIFF_FORMAT_PATCH))
227                 revs->combine_merges = revs->dense_combined_merges = 1;
228
229         return 0;
230 }
231
232 static int is_outside_repo(const char *path, int nongit, const char *prefix)
233 {
234         int i;
235         if (nongit || !strcmp(path, "-") || is_absolute_path(path))
236                 return 1;
237         if (prefixcmp(path, "../"))
238                 return 0;
239         if (!prefix)
240                 return 1;
241         for (i = strlen(prefix); !prefixcmp(path, "../"); ) {
242                 while (i > 0 && prefix[i - 1] != '/')
243                         i--;
244                 if (--i < 0)
245                         return 1;
246                 path += 3;
247         }
248         return 0;
249 }
250
251 int setup_diff_no_index(struct rev_info *revs,
252                 int argc, const char ** argv, int nongit, const char *prefix)
253 {
254         int i;
255         for (i = 1; i < argc; i++)
256                 if (argv[i][0] != '-' || argv[i][1] == '\0')
257                         break;
258                 else if (!strcmp(argv[i], "--")) {
259                         i++;
260                         break;
261                 } else if (i < argc - 3 && !strcmp(argv[i], "--no-index")) {
262                         i = argc - 3;
263                         DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS);
264                         break;
265                 }
266         if (argc != i + 2 || (!is_outside_repo(argv[i + 1], nongit, prefix) &&
267                                 !is_outside_repo(argv[i], nongit, prefix)))
268                 return -1;
269
270         diff_setup(&revs->diffopt);
271         for (i = 1; i < argc - 2; )
272                 if (!strcmp(argv[i], "--no-index"))
273                         i++;
274                 else {
275                         int j = diff_opt_parse(&revs->diffopt,
276                                         argv + i, argc - i);
277                         if (!j)
278                                 die("invalid diff option/value: %s", argv[i]);
279                         i += j;
280                 }
281
282         if (prefix) {
283                 int len = strlen(prefix);
284
285                 revs->diffopt.paths = xcalloc(2, sizeof(char*));
286                 for (i = 0; i < 2; i++) {
287                         const char *p = argv[argc - 2 + i];
288                         /*
289                          * stdin should be spelled as '-'; if you have
290                          * path that is '-', spell it as ./-.
291                          */
292                         p = (strcmp(p, "-")
293                              ? xstrdup(prefix_filename(prefix, len, p))
294                              : p);
295                         revs->diffopt.paths[i] = p;
296                 }
297         }
298         else
299                 revs->diffopt.paths = argv + argc - 2;
300         revs->diffopt.nr_paths = 2;
301         DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
302         revs->max_count = -2;
303         if (diff_setup_done(&revs->diffopt) < 0)
304                 die("diff_setup_done failed");
305         return 0;
306 }
307
308 int run_diff_files_cmd(struct rev_info *revs, int argc, const char **argv)
309 {
310         unsigned int options;
311
312         if (handle_diff_files_args(revs, argc, argv, &options))
313                 return -1;
314
315         if (DIFF_OPT_TST(&revs->diffopt, NO_INDEX)) {
316                 if (revs->diffopt.nr_paths != 2)
317                         return error("need two files/directories with --no-index");
318                 if (queue_diff(&revs->diffopt, revs->diffopt.paths[0],
319                                 revs->diffopt.paths[1]))
320                         return -1;
321                 diffcore_std(&revs->diffopt);
322                 diff_flush(&revs->diffopt);
323                 /*
324                  * The return code for --no-index imitates diff(1):
325                  * 0 = no changes, 1 = changes, else error
326                  */
327                 return revs->diffopt.found_changes;
328         }
329
330         if (read_cache() < 0) {
331                 perror("read_cache");
332                 return -1;
333         }
334         return run_diff_files(revs, options);
335 }
336
337 int run_diff_files(struct rev_info *revs, unsigned int option)
338 {
339         int entries, i;
340         int diff_unmerged_stage = revs->max_count;
341         int silent_on_removed = option & DIFF_SILENT_ON_REMOVED;
342         unsigned ce_option = ((option & DIFF_RACY_IS_MODIFIED)
343                               ? CE_MATCH_RACY_IS_DIRTY : 0);
344
345         if (diff_unmerged_stage < 0)
346                 diff_unmerged_stage = 2;
347         entries = active_nr;
348         for (i = 0; i < entries; i++) {
349                 struct stat st;
350                 unsigned int oldmode, newmode;
351                 struct cache_entry *ce = active_cache[i];
352                 int changed;
353
354                 if (DIFF_OPT_TST(&revs->diffopt, QUIET) &&
355                         DIFF_OPT_TST(&revs->diffopt, HAS_CHANGES))
356                         break;
357
358                 if (!ce_path_match(ce, revs->prune_data))
359                         continue;
360
361                 if (ce_stage(ce)) {
362                         struct combine_diff_path *dpath;
363                         int num_compare_stages = 0;
364                         size_t path_len;
365
366                         path_len = ce_namelen(ce);
367
368                         dpath = xmalloc(combine_diff_path_size(5, path_len));
369                         dpath->path = (char *) &(dpath->parent[5]);
370
371                         dpath->next = NULL;
372                         dpath->len = path_len;
373                         memcpy(dpath->path, ce->name, path_len);
374                         dpath->path[path_len] = '\0';
375                         hashclr(dpath->sha1);
376                         memset(&(dpath->parent[0]), 0,
377                                sizeof(struct combine_diff_parent)*5);
378
379                         if (lstat(ce->name, &st) < 0) {
380                                 if (errno != ENOENT && errno != ENOTDIR) {
381                                         perror(ce->name);
382                                         continue;
383                                 }
384                                 if (silent_on_removed)
385                                         continue;
386                         }
387                         else
388                                 dpath->mode = ce_mode_from_stat(ce, st.st_mode);
389
390                         while (i < entries) {
391                                 struct cache_entry *nce = active_cache[i];
392                                 int stage;
393
394                                 if (strcmp(ce->name, nce->name))
395                                         break;
396
397                                 /* Stage #2 (ours) is the first parent,
398                                  * stage #3 (theirs) is the second.
399                                  */
400                                 stage = ce_stage(nce);
401                                 if (2 <= stage) {
402                                         int mode = nce->ce_mode;
403                                         num_compare_stages++;
404                                         hashcpy(dpath->parent[stage-2].sha1, nce->sha1);
405                                         dpath->parent[stage-2].mode = ce_mode_from_stat(nce, mode);
406                                         dpath->parent[stage-2].status =
407                                                 DIFF_STATUS_MODIFIED;
408                                 }
409
410                                 /* diff against the proper unmerged stage */
411                                 if (stage == diff_unmerged_stage)
412                                         ce = nce;
413                                 i++;
414                         }
415                         /*
416                          * Compensate for loop update
417                          */
418                         i--;
419
420                         if (revs->combine_merges && num_compare_stages == 2) {
421                                 show_combined_diff(dpath, 2,
422                                                    revs->dense_combined_merges,
423                                                    revs);
424                                 free(dpath);
425                                 continue;
426                         }
427                         free(dpath);
428                         dpath = NULL;
429
430                         /*
431                          * Show the diff for the 'ce' if we found the one
432                          * from the desired stage.
433                          */
434                         diff_unmerge(&revs->diffopt, ce->name, 0, null_sha1);
435                         if (ce_stage(ce) != diff_unmerged_stage)
436                                 continue;
437                 }
438
439                 if (ce_uptodate(ce))
440                         continue;
441                 if (lstat(ce->name, &st) < 0) {
442                         if (errno != ENOENT && errno != ENOTDIR) {
443                                 perror(ce->name);
444                                 continue;
445                         }
446                         if (silent_on_removed)
447                                 continue;
448                         diff_addremove(&revs->diffopt, '-', ce->ce_mode,
449                                        ce->sha1, ce->name, NULL);
450                         continue;
451                 }
452                 changed = ce_match_stat(ce, &st, ce_option);
453                 if (!changed && !DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
454                         continue;
455                 oldmode = ce->ce_mode;
456                 newmode = ce_mode_from_stat(ce, st.st_mode);
457                 diff_change(&revs->diffopt, oldmode, newmode,
458                             ce->sha1, (changed ? null_sha1 : ce->sha1),
459                             ce->name, NULL);
460
461         }
462         diffcore_std(&revs->diffopt);
463         diff_flush(&revs->diffopt);
464         return 0;
465 }
466
467 /*
468  * diff-index
469  */
470
471 /* A file entry went away or appeared */
472 static void diff_index_show_file(struct rev_info *revs,
473                                  const char *prefix,
474                                  struct cache_entry *ce,
475                                  const unsigned char *sha1, unsigned int mode)
476 {
477         diff_addremove(&revs->diffopt, prefix[0], mode,
478                        sha1, ce->name, NULL);
479 }
480
481 static int get_stat_data(struct cache_entry *ce,
482                          const unsigned char **sha1p,
483                          unsigned int *modep,
484                          int cached, int match_missing)
485 {
486         const unsigned char *sha1 = ce->sha1;
487         unsigned int mode = ce->ce_mode;
488
489         if (!cached) {
490                 int changed;
491                 struct stat st;
492                 if (lstat(ce->name, &st) < 0) {
493                         if (errno == ENOENT && match_missing) {
494                                 *sha1p = sha1;
495                                 *modep = mode;
496                                 return 0;
497                         }
498                         return -1;
499                 }
500                 changed = ce_match_stat(ce, &st, 0);
501                 if (changed) {
502                         mode = ce_mode_from_stat(ce, st.st_mode);
503                         sha1 = null_sha1;
504                 }
505         }
506
507         *sha1p = sha1;
508         *modep = mode;
509         return 0;
510 }
511
512 static void show_new_file(struct rev_info *revs,
513                           struct cache_entry *new,
514                           int cached, int match_missing)
515 {
516         const unsigned char *sha1;
517         unsigned int mode;
518
519         /* New file in the index: it might actually be different in
520          * the working copy.
521          */
522         if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0)
523                 return;
524
525         diff_index_show_file(revs, "+", new, sha1, mode);
526 }
527
528 static int show_modified(struct rev_info *revs,
529                          struct cache_entry *old,
530                          struct cache_entry *new,
531                          int report_missing,
532                          int cached, int match_missing)
533 {
534         unsigned int mode, oldmode;
535         const unsigned char *sha1;
536
537         if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0) {
538                 if (report_missing)
539                         diff_index_show_file(revs, "-", old,
540                                              old->sha1, old->ce_mode);
541                 return -1;
542         }
543
544         if (revs->combine_merges && !cached &&
545             (hashcmp(sha1, old->sha1) || hashcmp(old->sha1, new->sha1))) {
546                 struct combine_diff_path *p;
547                 int pathlen = ce_namelen(new);
548
549                 p = xmalloc(combine_diff_path_size(2, pathlen));
550                 p->path = (char *) &p->parent[2];
551                 p->next = NULL;
552                 p->len = pathlen;
553                 memcpy(p->path, new->name, pathlen);
554                 p->path[pathlen] = 0;
555                 p->mode = mode;
556                 hashclr(p->sha1);
557                 memset(p->parent, 0, 2 * sizeof(struct combine_diff_parent));
558                 p->parent[0].status = DIFF_STATUS_MODIFIED;
559                 p->parent[0].mode = new->ce_mode;
560                 hashcpy(p->parent[0].sha1, new->sha1);
561                 p->parent[1].status = DIFF_STATUS_MODIFIED;
562                 p->parent[1].mode = old->ce_mode;
563                 hashcpy(p->parent[1].sha1, old->sha1);
564                 show_combined_diff(p, 2, revs->dense_combined_merges, revs);
565                 free(p);
566                 return 0;
567         }
568
569         oldmode = old->ce_mode;
570         if (mode == oldmode && !hashcmp(sha1, old->sha1) &&
571             !DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
572                 return 0;
573
574         diff_change(&revs->diffopt, oldmode, mode,
575                     old->sha1, sha1, old->name, NULL);
576         return 0;
577 }
578
579 /*
580  * This turns all merge entries into "stage 3". That guarantees that
581  * when we read in the new tree (into "stage 1"), we won't lose sight
582  * of the fact that we had unmerged entries.
583  */
584 static void mark_merge_entries(void)
585 {
586         int i;
587         for (i = 0; i < active_nr; i++) {
588                 struct cache_entry *ce = active_cache[i];
589                 if (!ce_stage(ce))
590                         continue;
591                 ce->ce_flags |= CE_STAGEMASK;
592         }
593 }
594
595 /*
596  * This gets a mix of an existing index and a tree, one pathname entry
597  * at a time. The index entry may be a single stage-0 one, but it could
598  * also be multiple unmerged entries (in which case idx_pos/idx_nr will
599  * give you the position and number of entries in the index).
600  */
601 static void do_oneway_diff(struct unpack_trees_options *o,
602         struct cache_entry *idx,
603         struct cache_entry *tree)
604 {
605         struct rev_info *revs = o->unpack_data;
606         int match_missing, cached;
607
608         /*
609          * Backward compatibility wart - "diff-index -m" does
610          * not mean "do not ignore merges", but "match_missing".
611          *
612          * But with the revision flag parsing, that's found in
613          * "!revs->ignore_merges".
614          */
615         cached = o->index_only;
616         match_missing = !revs->ignore_merges;
617
618         if (cached && idx && ce_stage(idx)) {
619                 if (tree)
620                         diff_unmerge(&revs->diffopt, idx->name, idx->ce_mode, idx->sha1);
621                 return;
622         }
623
624         /*
625          * Something added to the tree?
626          */
627         if (!tree) {
628                 show_new_file(revs, idx, cached, match_missing);
629                 return;
630         }
631
632         /*
633          * Something removed from the tree?
634          */
635         if (!idx) {
636                 diff_index_show_file(revs, "-", tree, tree->sha1, tree->ce_mode);
637                 return;
638         }
639
640         /* Show difference between old and new */
641         show_modified(revs, tree, idx, 1, cached, match_missing);
642 }
643
644 static inline void skip_same_name(struct cache_entry *ce, struct unpack_trees_options *o)
645 {
646         int len = ce_namelen(ce);
647         const struct index_state *index = o->src_index;
648
649         while (o->pos < index->cache_nr) {
650                 struct cache_entry *next = index->cache[o->pos];
651                 if (len != ce_namelen(next))
652                         break;
653                 if (memcmp(ce->name, next->name, len))
654                         break;
655                 o->pos++;
656         }
657 }
658
659 /*
660  * The unpack_trees() interface is designed for merging, so
661  * the different source entries are designed primarily for
662  * the source trees, with the old index being really mainly
663  * used for being replaced by the result.
664  *
665  * For diffing, the index is more important, and we only have a
666  * single tree.
667  *
668  * We're supposed to return how many index entries we want to skip.
669  *
670  * This wrapper makes it all more readable, and takes care of all
671  * the fairly complex unpack_trees() semantic requirements, including
672  * the skipping, the path matching, the type conflict cases etc.
673  */
674 static int oneway_diff(struct cache_entry **src, struct unpack_trees_options *o)
675 {
676         struct cache_entry *idx = src[0];
677         struct cache_entry *tree = src[1];
678         struct rev_info *revs = o->unpack_data;
679
680         if (idx && ce_stage(idx))
681                 skip_same_name(idx, o);
682
683         /*
684          * Unpack-trees generates a DF/conflict entry if
685          * there was a directory in the index and a tree
686          * in the tree. From a diff standpoint, that's a
687          * delete of the tree and a create of the file.
688          */
689         if (tree == o->df_conflict_entry)
690                 tree = NULL;
691
692         if (ce_path_match(idx ? idx : tree, revs->prune_data))
693                 do_oneway_diff(o, idx, tree);
694
695         return 0;
696 }
697
698 int run_diff_index(struct rev_info *revs, int cached)
699 {
700         struct object *ent;
701         struct tree *tree;
702         const char *tree_name;
703         struct unpack_trees_options opts;
704         struct tree_desc t;
705
706         mark_merge_entries();
707
708         ent = revs->pending.objects[0].item;
709         tree_name = revs->pending.objects[0].name;
710         tree = parse_tree_indirect(ent->sha1);
711         if (!tree)
712                 return error("bad tree object %s", tree_name);
713
714         memset(&opts, 0, sizeof(opts));
715         opts.head_idx = 1;
716         opts.index_only = cached;
717         opts.merge = 1;
718         opts.fn = oneway_diff;
719         opts.unpack_data = revs;
720         opts.src_index = &the_index;
721         opts.dst_index = NULL;
722
723         init_tree_desc(&t, tree->buffer, tree->size);
724         if (unpack_trees(1, &t, &opts))
725                 exit(128);
726
727         diffcore_std(&revs->diffopt);
728         diff_flush(&revs->diffopt);
729         return 0;
730 }
731
732 int do_diff_cache(const unsigned char *tree_sha1, struct diff_options *opt)
733 {
734         struct tree *tree;
735         struct rev_info revs;
736         int i;
737         struct cache_entry **dst;
738         struct cache_entry *last = NULL;
739         struct unpack_trees_options opts;
740         struct tree_desc t;
741
742         /*
743          * This is used by git-blame to run diff-cache internally;
744          * it potentially needs to repeatedly run this, so we will
745          * start by removing the higher order entries the last round
746          * left behind.
747          */
748         dst = active_cache;
749         for (i = 0; i < active_nr; i++) {
750                 struct cache_entry *ce = active_cache[i];
751                 if (ce_stage(ce)) {
752                         if (last && !strcmp(ce->name, last->name))
753                                 continue;
754                         cache_tree_invalidate_path(active_cache_tree,
755                                                    ce->name);
756                         last = ce;
757                         ce->ce_flags |= CE_REMOVE;
758                 }
759                 *dst++ = ce;
760         }
761         active_nr = dst - active_cache;
762
763         init_revisions(&revs, NULL);
764         revs.prune_data = opt->paths;
765         tree = parse_tree_indirect(tree_sha1);
766         if (!tree)
767                 die("bad tree object %s", sha1_to_hex(tree_sha1));
768
769         memset(&opts, 0, sizeof(opts));
770         opts.head_idx = 1;
771         opts.index_only = 1;
772         opts.merge = 1;
773         opts.fn = oneway_diff;
774         opts.unpack_data = &revs;
775         opts.src_index = &the_index;
776         opts.dst_index = &the_index;
777
778         init_tree_desc(&t, tree->buffer, tree->size);
779         if (unpack_trees(1, &t, &opts))
780                 exit(128);
781         return 0;
782 }