Merge branch 'cn/commit-amend-doc'
[git] / unpack-trees.c
1 #define NO_THE_INDEX_COMPATIBILITY_MACROS
2 #include "cache.h"
3 #include "dir.h"
4 #include "tree.h"
5 #include "tree-walk.h"
6 #include "cache-tree.h"
7 #include "unpack-trees.h"
8 #include "progress.h"
9 #include "refs.h"
10 #include "attr.h"
11
12 /*
13  * Error messages expected by scripts out of plumbing commands such as
14  * read-tree.  Non-scripted Porcelain is not required to use these messages
15  * and in fact are encouraged to reword them to better suit their particular
16  * situation better.  See how "git checkout" and "git merge" replaces
17  * them using setup_unpack_trees_porcelain(), for example.
18  */
19 static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
20         /* ERROR_WOULD_OVERWRITE */
21         "Entry '%s' would be overwritten by merge. Cannot merge.",
22
23         /* ERROR_NOT_UPTODATE_FILE */
24         "Entry '%s' not uptodate. Cannot merge.",
25
26         /* ERROR_NOT_UPTODATE_DIR */
27         "Updating '%s' would lose untracked files in it",
28
29         /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
30         "Untracked working tree file '%s' would be overwritten by merge.",
31
32         /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
33         "Untracked working tree file '%s' would be removed by merge.",
34
35         /* ERROR_BIND_OVERLAP */
36         "Entry '%s' overlaps with '%s'.  Cannot bind.",
37
38         /* ERROR_SPARSE_NOT_UPTODATE_FILE */
39         "Entry '%s' not uptodate. Cannot update sparse checkout.",
40
41         /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
42         "Working tree file '%s' would be overwritten by sparse checkout update.",
43
44         /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
45         "Working tree file '%s' would be removed by sparse checkout update.",
46 };
47
48 #define ERRORMSG(o,type) \
49         ( ((o) && (o)->msgs[(type)]) \
50           ? ((o)->msgs[(type)])      \
51           : (unpack_plumbing_errors[(type)]) )
52
53 void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
54                                   const char *cmd)
55 {
56         int i;
57         const char **msgs = opts->msgs;
58         const char *msg;
59         char *tmp;
60         const char *cmd2 = strcmp(cmd, "checkout") ? cmd : "switch branches";
61         if (advice_commit_before_merge)
62                 msg = "Your local changes to the following files would be overwritten by %s:\n%%s"
63                         "Please, commit your changes or stash them before you can %s.";
64         else
65                 msg = "Your local changes to the following files would be overwritten by %s:\n%%s";
66         tmp = xmalloc(strlen(msg) + strlen(cmd) + strlen(cmd2) - 2);
67         sprintf(tmp, msg, cmd, cmd2);
68         msgs[ERROR_WOULD_OVERWRITE] = tmp;
69         msgs[ERROR_NOT_UPTODATE_FILE] = tmp;
70
71         msgs[ERROR_NOT_UPTODATE_DIR] =
72                 "Updating the following directories would lose untracked files in it:\n%s";
73
74         if (advice_commit_before_merge)
75                 msg = "The following untracked working tree files would be %s by %s:\n%%s"
76                         "Please move or remove them before you can %s.";
77         else
78                 msg = "The following untracked working tree files would be %s by %s:\n%%s";
79         tmp = xmalloc(strlen(msg) + strlen(cmd) + strlen("removed") + strlen(cmd2) - 4);
80         sprintf(tmp, msg, "removed", cmd, cmd2);
81         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = tmp;
82         tmp = xmalloc(strlen(msg) + strlen(cmd) + strlen("overwritten") + strlen(cmd2) - 4);
83         sprintf(tmp, msg, "overwritten", cmd, cmd2);
84         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = tmp;
85
86         /*
87          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
88          * cannot easily display it as a list.
89          */
90         msgs[ERROR_BIND_OVERLAP] = "Entry '%s' overlaps with '%s'.  Cannot bind.";
91
92         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
93                 "Cannot update sparse checkout: the following entries are not up-to-date:\n%s";
94         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
95                 "The following Working tree files would be overwritten by sparse checkout update:\n%s";
96         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
97                 "The following Working tree files would be removed by sparse checkout update:\n%s";
98
99         opts->show_all_errors = 1;
100         /* rejected paths may not have a static buffer */
101         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
102                 opts->unpack_rejects[i].strdup_strings = 1;
103 }
104
105 static void do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
106                          unsigned int set, unsigned int clear)
107 {
108         clear |= CE_HASHED | CE_UNHASHED;
109
110         if (set & CE_REMOVE)
111                 set |= CE_WT_REMOVE;
112
113         ce->next = NULL;
114         ce->ce_flags = (ce->ce_flags & ~clear) | set;
115         add_index_entry(&o->result, ce,
116                         ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
117 }
118
119 static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
120         unsigned int set, unsigned int clear)
121 {
122         unsigned int size = ce_size(ce);
123         struct cache_entry *new = xmalloc(size);
124
125         memcpy(new, ce, size);
126         do_add_entry(o, new, set, clear);
127 }
128
129 /*
130  * add error messages on path <path>
131  * corresponding to the type <e> with the message <msg>
132  * indicating if it should be display in porcelain or not
133  */
134 static int add_rejected_path(struct unpack_trees_options *o,
135                              enum unpack_trees_error_types e,
136                              const char *path)
137 {
138         if (!o->show_all_errors)
139                 return error(ERRORMSG(o, e), path);
140
141         /*
142          * Otherwise, insert in a list for future display by
143          * display_error_msgs()
144          */
145         string_list_append(&o->unpack_rejects[e], path);
146         return -1;
147 }
148
149 /*
150  * display all the error messages stored in a nice way
151  */
152 static void display_error_msgs(struct unpack_trees_options *o)
153 {
154         int e, i;
155         int something_displayed = 0;
156         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
157                 struct string_list *rejects = &o->unpack_rejects[e];
158                 if (rejects->nr > 0) {
159                         struct strbuf path = STRBUF_INIT;
160                         something_displayed = 1;
161                         for (i = 0; i < rejects->nr; i++)
162                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
163                         error(ERRORMSG(o, e), path.buf);
164                         strbuf_release(&path);
165                 }
166                 string_list_clear(rejects, 0);
167         }
168         if (something_displayed)
169                 fprintf(stderr, "Aborting\n");
170 }
171
172 /*
173  * Unlink the last component and schedule the leading directories for
174  * removal, such that empty directories get removed.
175  */
176 static void unlink_entry(struct cache_entry *ce)
177 {
178         if (!check_leading_path(ce->name, ce_namelen(ce)))
179                 return;
180         if (remove_or_warn(ce->ce_mode, ce->name))
181                 return;
182         schedule_dir_for_removal(ce->name, ce_namelen(ce));
183 }
184
185 static struct checkout state;
186 static int check_updates(struct unpack_trees_options *o)
187 {
188         unsigned cnt = 0, total = 0;
189         struct progress *progress = NULL;
190         struct index_state *index = &o->result;
191         int i;
192         int errs = 0;
193
194         if (o->update && o->verbose_update) {
195                 for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
196                         struct cache_entry *ce = index->cache[cnt];
197                         if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
198                                 total++;
199                 }
200
201                 progress = start_progress_delay("Checking out files",
202                                                 total, 50, 1);
203                 cnt = 0;
204         }
205
206         if (o->update)
207                 git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
208         for (i = 0; i < index->cache_nr; i++) {
209                 struct cache_entry *ce = index->cache[i];
210
211                 if (ce->ce_flags & CE_WT_REMOVE) {
212                         display_progress(progress, ++cnt);
213                         if (o->update && !o->dry_run)
214                                 unlink_entry(ce);
215                         continue;
216                 }
217         }
218         remove_marked_cache_entries(&o->result);
219         remove_scheduled_dirs();
220
221         for (i = 0; i < index->cache_nr; i++) {
222                 struct cache_entry *ce = index->cache[i];
223
224                 if (ce->ce_flags & CE_UPDATE) {
225                         display_progress(progress, ++cnt);
226                         ce->ce_flags &= ~CE_UPDATE;
227                         if (o->update && !o->dry_run) {
228                                 errs |= checkout_entry(ce, &state, NULL);
229                         }
230                 }
231         }
232         stop_progress(&progress);
233         if (o->update)
234                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
235         return errs != 0;
236 }
237
238 static int verify_uptodate_sparse(struct cache_entry *ce, struct unpack_trees_options *o);
239 static int verify_absent_sparse(struct cache_entry *ce, enum unpack_trees_error_types, struct unpack_trees_options *o);
240
241 static int apply_sparse_checkout(struct cache_entry *ce, struct unpack_trees_options *o)
242 {
243         int was_skip_worktree = ce_skip_worktree(ce);
244
245         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
246                 ce->ce_flags |= CE_SKIP_WORKTREE;
247         else
248                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
249
250         /*
251          * if (!was_skip_worktree && !ce_skip_worktree()) {
252          *      This is perfectly normal. Move on;
253          * }
254          */
255
256         /*
257          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
258          * area as a result of ce_skip_worktree() shortcuts in
259          * verify_absent() and verify_uptodate().
260          * Make sure they don't modify worktree if they are already
261          * outside checkout area
262          */
263         if (was_skip_worktree && ce_skip_worktree(ce)) {
264                 ce->ce_flags &= ~CE_UPDATE;
265
266                 /*
267                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
268                  * on to get that file removed from both index and worktree.
269                  * If that file is already outside worktree area, don't
270                  * bother remove it.
271                  */
272                 if (ce->ce_flags & CE_REMOVE)
273                         ce->ce_flags &= ~CE_WT_REMOVE;
274         }
275
276         if (!was_skip_worktree && ce_skip_worktree(ce)) {
277                 /*
278                  * If CE_UPDATE is set, verify_uptodate() must be called already
279                  * also stat info may have lost after merged_entry() so calling
280                  * verify_uptodate() again may fail
281                  */
282                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
283                         return -1;
284                 ce->ce_flags |= CE_WT_REMOVE;
285         }
286         if (was_skip_worktree && !ce_skip_worktree(ce)) {
287                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
288                         return -1;
289                 ce->ce_flags |= CE_UPDATE;
290         }
291         return 0;
292 }
293
294 static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
295 {
296         int ret = o->fn(src, o);
297         if (ret > 0)
298                 ret = 0;
299         return ret;
300 }
301
302 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
303 {
304         ce->ce_flags |= CE_UNPACKED;
305
306         if (o->cache_bottom < o->src_index->cache_nr &&
307             o->src_index->cache[o->cache_bottom] == ce) {
308                 int bottom = o->cache_bottom;
309                 while (bottom < o->src_index->cache_nr &&
310                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
311                         bottom++;
312                 o->cache_bottom = bottom;
313         }
314 }
315
316 static void mark_all_ce_unused(struct index_state *index)
317 {
318         int i;
319         for (i = 0; i < index->cache_nr; i++)
320                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
321 }
322
323 static int locate_in_src_index(struct cache_entry *ce,
324                                struct unpack_trees_options *o)
325 {
326         struct index_state *index = o->src_index;
327         int len = ce_namelen(ce);
328         int pos = index_name_pos(index, ce->name, len);
329         if (pos < 0)
330                 pos = -1 - pos;
331         return pos;
332 }
333
334 /*
335  * We call unpack_index_entry() with an unmerged cache entry
336  * only in diff-index, and it wants a single callback.  Skip
337  * the other unmerged entry with the same name.
338  */
339 static void mark_ce_used_same_name(struct cache_entry *ce,
340                                    struct unpack_trees_options *o)
341 {
342         struct index_state *index = o->src_index;
343         int len = ce_namelen(ce);
344         int pos;
345
346         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
347                 struct cache_entry *next = index->cache[pos];
348                 if (len != ce_namelen(next) ||
349                     memcmp(ce->name, next->name, len))
350                         break;
351                 mark_ce_used(next, o);
352         }
353 }
354
355 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
356 {
357         const struct index_state *index = o->src_index;
358         int pos = o->cache_bottom;
359
360         while (pos < index->cache_nr) {
361                 struct cache_entry *ce = index->cache[pos];
362                 if (!(ce->ce_flags & CE_UNPACKED))
363                         return ce;
364                 pos++;
365         }
366         return NULL;
367 }
368
369 static void add_same_unmerged(struct cache_entry *ce,
370                               struct unpack_trees_options *o)
371 {
372         struct index_state *index = o->src_index;
373         int len = ce_namelen(ce);
374         int pos = index_name_pos(index, ce->name, len);
375
376         if (0 <= pos)
377                 die("programming error in a caller of mark_ce_used_same_name");
378         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
379                 struct cache_entry *next = index->cache[pos];
380                 if (len != ce_namelen(next) ||
381                     memcmp(ce->name, next->name, len))
382                         break;
383                 add_entry(o, next, 0, 0);
384                 mark_ce_used(next, o);
385         }
386 }
387
388 static int unpack_index_entry(struct cache_entry *ce,
389                               struct unpack_trees_options *o)
390 {
391         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
392         int ret;
393
394         src[0] = ce;
395
396         mark_ce_used(ce, o);
397         if (ce_stage(ce)) {
398                 if (o->skip_unmerged) {
399                         add_entry(o, ce, 0, 0);
400                         return 0;
401                 }
402         }
403         ret = call_unpack_fn(src, o);
404         if (ce_stage(ce))
405                 mark_ce_used_same_name(ce, o);
406         return ret;
407 }
408
409 static int find_cache_pos(struct traverse_info *, const struct name_entry *);
410
411 static void restore_cache_bottom(struct traverse_info *info, int bottom)
412 {
413         struct unpack_trees_options *o = info->data;
414
415         if (o->diff_index_cached)
416                 return;
417         o->cache_bottom = bottom;
418 }
419
420 static int switch_cache_bottom(struct traverse_info *info)
421 {
422         struct unpack_trees_options *o = info->data;
423         int ret, pos;
424
425         if (o->diff_index_cached)
426                 return 0;
427         ret = o->cache_bottom;
428         pos = find_cache_pos(info->prev, &info->name);
429
430         if (pos < -1)
431                 o->cache_bottom = -2 - pos;
432         else if (pos < 0)
433                 o->cache_bottom = o->src_index->cache_nr;
434         return ret;
435 }
436
437 static int traverse_trees_recursive(int n, unsigned long dirmask,
438                                     unsigned long df_conflicts,
439                                     struct name_entry *names,
440                                     struct traverse_info *info)
441 {
442         int i, ret, bottom;
443         struct tree_desc t[MAX_UNPACK_TREES];
444         void *buf[MAX_UNPACK_TREES];
445         struct traverse_info newinfo;
446         struct name_entry *p;
447
448         p = names;
449         while (!p->mode)
450                 p++;
451
452         newinfo = *info;
453         newinfo.prev = info;
454         newinfo.pathspec = info->pathspec;
455         newinfo.name = *p;
456         newinfo.pathlen += tree_entry_len(p) + 1;
457         newinfo.conflicts |= df_conflicts;
458
459         for (i = 0; i < n; i++, dirmask >>= 1) {
460                 const unsigned char *sha1 = NULL;
461                 if (dirmask & 1)
462                         sha1 = names[i].sha1;
463                 buf[i] = fill_tree_descriptor(t+i, sha1);
464         }
465
466         bottom = switch_cache_bottom(&newinfo);
467         ret = traverse_trees(n, t, &newinfo);
468         restore_cache_bottom(&newinfo, bottom);
469
470         for (i = 0; i < n; i++)
471                 free(buf[i]);
472
473         return ret;
474 }
475
476 /*
477  * Compare the traverse-path to the cache entry without actually
478  * having to generate the textual representation of the traverse
479  * path.
480  *
481  * NOTE! This *only* compares up to the size of the traverse path
482  * itself - the caller needs to do the final check for the cache
483  * entry having more data at the end!
484  */
485 static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
486 {
487         int len, pathlen, ce_len;
488         const char *ce_name;
489
490         if (info->prev) {
491                 int cmp = do_compare_entry(ce, info->prev, &info->name);
492                 if (cmp)
493                         return cmp;
494         }
495         pathlen = info->pathlen;
496         ce_len = ce_namelen(ce);
497
498         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
499         if (ce_len < pathlen)
500                 return -1;
501
502         ce_len -= pathlen;
503         ce_name = ce->name + pathlen;
504
505         len = tree_entry_len(n);
506         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
507 }
508
509 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
510 {
511         int cmp = do_compare_entry(ce, info, n);
512         if (cmp)
513                 return cmp;
514
515         /*
516          * Even if the beginning compared identically, the ce should
517          * compare as bigger than a directory leading up to it!
518          */
519         return ce_namelen(ce) > traverse_path_len(info, n);
520 }
521
522 static int ce_in_traverse_path(const struct cache_entry *ce,
523                                const struct traverse_info *info)
524 {
525         if (!info->prev)
526                 return 1;
527         if (do_compare_entry(ce, info->prev, &info->name))
528                 return 0;
529         /*
530          * If ce (blob) is the same name as the path (which is a tree
531          * we will be descending into), it won't be inside it.
532          */
533         return (info->pathlen < ce_namelen(ce));
534 }
535
536 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
537 {
538         int len = traverse_path_len(info, n);
539         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
540
541         ce->ce_mode = create_ce_mode(n->mode);
542         ce->ce_flags = create_ce_flags(stage);
543         ce->ce_namelen = len;
544         hashcpy(ce->sha1, n->sha1);
545         make_traverse_path(ce->name, info, n);
546
547         return ce;
548 }
549
550 static int unpack_nondirectories(int n, unsigned long mask,
551                                  unsigned long dirmask,
552                                  struct cache_entry **src,
553                                  const struct name_entry *names,
554                                  const struct traverse_info *info)
555 {
556         int i;
557         struct unpack_trees_options *o = info->data;
558         unsigned long conflicts;
559
560         /* Do we have *only* directories? Nothing to do */
561         if (mask == dirmask && !src[0])
562                 return 0;
563
564         conflicts = info->conflicts;
565         if (o->merge)
566                 conflicts >>= 1;
567         conflicts |= dirmask;
568
569         /*
570          * Ok, we've filled in up to any potential index entry in src[0],
571          * now do the rest.
572          */
573         for (i = 0; i < n; i++) {
574                 int stage;
575                 unsigned int bit = 1ul << i;
576                 if (conflicts & bit) {
577                         src[i + o->merge] = o->df_conflict_entry;
578                         continue;
579                 }
580                 if (!(mask & bit))
581                         continue;
582                 if (!o->merge)
583                         stage = 0;
584                 else if (i + 1 < o->head_idx)
585                         stage = 1;
586                 else if (i + 1 > o->head_idx)
587                         stage = 3;
588                 else
589                         stage = 2;
590                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
591         }
592
593         if (o->merge)
594                 return call_unpack_fn(src, o);
595
596         for (i = 0; i < n; i++)
597                 if (src[i] && src[i] != o->df_conflict_entry)
598                         do_add_entry(o, src[i], 0, 0);
599         return 0;
600 }
601
602 static int unpack_failed(struct unpack_trees_options *o, const char *message)
603 {
604         discard_index(&o->result);
605         if (!o->gently && !o->exiting_early) {
606                 if (message)
607                         return error("%s", message);
608                 return -1;
609         }
610         return -1;
611 }
612
613 /* NEEDSWORK: give this a better name and share with tree-walk.c */
614 static int name_compare(const char *a, int a_len,
615                         const char *b, int b_len)
616 {
617         int len = (a_len < b_len) ? a_len : b_len;
618         int cmp = memcmp(a, b, len);
619         if (cmp)
620                 return cmp;
621         return (a_len - b_len);
622 }
623
624 /*
625  * The tree traversal is looking at name p.  If we have a matching entry,
626  * return it.  If name p is a directory in the index, do not return
627  * anything, as we will want to match it when the traversal descends into
628  * the directory.
629  */
630 static int find_cache_pos(struct traverse_info *info,
631                           const struct name_entry *p)
632 {
633         int pos;
634         struct unpack_trees_options *o = info->data;
635         struct index_state *index = o->src_index;
636         int pfxlen = info->pathlen;
637         int p_len = tree_entry_len(p);
638
639         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
640                 struct cache_entry *ce = index->cache[pos];
641                 const char *ce_name, *ce_slash;
642                 int cmp, ce_len;
643
644                 if (ce->ce_flags & CE_UNPACKED) {
645                         /*
646                          * cache_bottom entry is already unpacked, so
647                          * we can never match it; don't check it
648                          * again.
649                          */
650                         if (pos == o->cache_bottom)
651                                 ++o->cache_bottom;
652                         continue;
653                 }
654                 if (!ce_in_traverse_path(ce, info))
655                         continue;
656                 ce_name = ce->name + pfxlen;
657                 ce_slash = strchr(ce_name, '/');
658                 if (ce_slash)
659                         ce_len = ce_slash - ce_name;
660                 else
661                         ce_len = ce_namelen(ce) - pfxlen;
662                 cmp = name_compare(p->path, p_len, ce_name, ce_len);
663                 /*
664                  * Exact match; if we have a directory we need to
665                  * delay returning it.
666                  */
667                 if (!cmp)
668                         return ce_slash ? -2 - pos : pos;
669                 if (0 < cmp)
670                         continue; /* keep looking */
671                 /*
672                  * ce_name sorts after p->path; could it be that we
673                  * have files under p->path directory in the index?
674                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
675                  * have "t/a" in the index.
676                  */
677                 if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
678                     ce_name[p_len] < '/')
679                         continue; /* keep looking */
680                 break;
681         }
682         return -1;
683 }
684
685 static struct cache_entry *find_cache_entry(struct traverse_info *info,
686                                             const struct name_entry *p)
687 {
688         int pos = find_cache_pos(info, p);
689         struct unpack_trees_options *o = info->data;
690
691         if (0 <= pos)
692                 return o->src_index->cache[pos];
693         else
694                 return NULL;
695 }
696
697 static void debug_path(struct traverse_info *info)
698 {
699         if (info->prev) {
700                 debug_path(info->prev);
701                 if (*info->prev->name.path)
702                         putchar('/');
703         }
704         printf("%s", info->name.path);
705 }
706
707 static void debug_name_entry(int i, struct name_entry *n)
708 {
709         printf("ent#%d %06o %s\n", i,
710                n->path ? n->mode : 0,
711                n->path ? n->path : "(missing)");
712 }
713
714 static void debug_unpack_callback(int n,
715                                   unsigned long mask,
716                                   unsigned long dirmask,
717                                   struct name_entry *names,
718                                   struct traverse_info *info)
719 {
720         int i;
721         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
722                mask, dirmask, n);
723         debug_path(info);
724         putchar('\n');
725         for (i = 0; i < n; i++)
726                 debug_name_entry(i, names + i);
727 }
728
729 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
730 {
731         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
732         struct unpack_trees_options *o = info->data;
733         const struct name_entry *p = names;
734
735         /* Find first entry with a real name (we could use "mask" too) */
736         while (!p->mode)
737                 p++;
738
739         if (o->debug_unpack)
740                 debug_unpack_callback(n, mask, dirmask, names, info);
741
742         /* Are we supposed to look at the index too? */
743         if (o->merge) {
744                 while (1) {
745                         int cmp;
746                         struct cache_entry *ce;
747
748                         if (o->diff_index_cached)
749                                 ce = next_cache_entry(o);
750                         else
751                                 ce = find_cache_entry(info, p);
752
753                         if (!ce)
754                                 break;
755                         cmp = compare_entry(ce, info, p);
756                         if (cmp < 0) {
757                                 if (unpack_index_entry(ce, o) < 0)
758                                         return unpack_failed(o, NULL);
759                                 continue;
760                         }
761                         if (!cmp) {
762                                 if (ce_stage(ce)) {
763                                         /*
764                                          * If we skip unmerged index
765                                          * entries, we'll skip this
766                                          * entry *and* the tree
767                                          * entries associated with it!
768                                          */
769                                         if (o->skip_unmerged) {
770                                                 add_same_unmerged(ce, o);
771                                                 return mask;
772                                         }
773                                 }
774                                 src[0] = ce;
775                         }
776                         break;
777                 }
778         }
779
780         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
781                 return -1;
782
783         if (o->merge && src[0]) {
784                 if (ce_stage(src[0]))
785                         mark_ce_used_same_name(src[0], o);
786                 else
787                         mark_ce_used(src[0], o);
788         }
789
790         /* Now handle any directories.. */
791         if (dirmask) {
792                 unsigned long conflicts = mask & ~dirmask;
793                 if (o->merge) {
794                         conflicts <<= 1;
795                         if (src[0])
796                                 conflicts |= 1;
797                 }
798
799                 /* special case: "diff-index --cached" looking at a tree */
800                 if (o->diff_index_cached &&
801                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
802                         int matches;
803                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
804                                                                names, info);
805                         /*
806                          * Everything under the name matches; skip the
807                          * entire hierarchy.  diff_index_cached codepath
808                          * special cases D/F conflicts in such a way that
809                          * it does not do any look-ahead, so this is safe.
810                          */
811                         if (matches) {
812                                 o->cache_bottom += matches;
813                                 return mask;
814                         }
815                 }
816
817                 if (traverse_trees_recursive(n, dirmask, conflicts,
818                                              names, info) < 0)
819                         return -1;
820                 return mask;
821         }
822
823         return mask;
824 }
825
826 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
827                             char *prefix, int prefix_len,
828                             int select_mask, int clear_mask,
829                             struct exclude_list *el, int defval);
830
831 /* Whole directory matching */
832 static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
833                               char *prefix, int prefix_len,
834                               char *basename,
835                               int select_mask, int clear_mask,
836                               struct exclude_list *el, int defval)
837 {
838         struct cache_entry **cache_end;
839         int dtype = DT_DIR;
840         int ret = is_excluded_from_list(prefix, prefix_len,
841                                         basename, &dtype, el);
842
843         prefix[prefix_len++] = '/';
844
845         /* If undecided, use matching result of parent dir in defval */
846         if (ret < 0)
847                 ret = defval;
848
849         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
850                 struct cache_entry *ce = *cache_end;
851                 if (strncmp(ce->name, prefix, prefix_len))
852                         break;
853         }
854
855         /*
856          * TODO: check el, if there are no patterns that may conflict
857          * with ret (iow, we know in advance the incl/excl
858          * decision for the entire directory), clear flag here without
859          * calling clear_ce_flags_1(). That function will call
860          * the expensive is_excluded_from_list() on every entry.
861          */
862         return clear_ce_flags_1(cache, cache_end - cache,
863                                 prefix, prefix_len,
864                                 select_mask, clear_mask,
865                                 el, ret);
866 }
867
868 /*
869  * Traverse the index, find every entry that matches according to
870  * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
871  * number of traversed entries.
872  *
873  * If select_mask is non-zero, only entries whose ce_flags has on of
874  * those bits enabled are traversed.
875  *
876  * cache        : pointer to an index entry
877  * prefix_len   : an offset to its path
878  *
879  * The current path ("prefix") including the trailing '/' is
880  *   cache[0]->name[0..(prefix_len-1)]
881  * Top level path has prefix_len zero.
882  */
883 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
884                             char *prefix, int prefix_len,
885                             int select_mask, int clear_mask,
886                             struct exclude_list *el, int defval)
887 {
888         struct cache_entry **cache_end = cache + nr;
889
890         /*
891          * Process all entries that have the given prefix and meet
892          * select_mask condition
893          */
894         while(cache != cache_end) {
895                 struct cache_entry *ce = *cache;
896                 const char *name, *slash;
897                 int len, dtype, ret;
898
899                 if (select_mask && !(ce->ce_flags & select_mask)) {
900                         cache++;
901                         continue;
902                 }
903
904                 if (prefix_len && strncmp(ce->name, prefix, prefix_len))
905                         break;
906
907                 name = ce->name + prefix_len;
908                 slash = strchr(name, '/');
909
910                 /* If it's a directory, try whole directory match first */
911                 if (slash) {
912                         int processed;
913
914                         len = slash - name;
915                         memcpy(prefix + prefix_len, name, len);
916
917                         /*
918                          * terminate the string (no trailing slash),
919                          * clear_c_f_dir needs it
920                          */
921                         prefix[prefix_len + len] = '\0';
922                         processed = clear_ce_flags_dir(cache, cache_end - cache,
923                                                        prefix, prefix_len + len,
924                                                        prefix + prefix_len,
925                                                        select_mask, clear_mask,
926                                                        el, defval);
927
928                         /* clear_c_f_dir eats a whole dir already? */
929                         if (processed) {
930                                 cache += processed;
931                                 continue;
932                         }
933
934                         prefix[prefix_len + len++] = '/';
935                         cache += clear_ce_flags_1(cache, cache_end - cache,
936                                                   prefix, prefix_len + len,
937                                                   select_mask, clear_mask, el, defval);
938                         continue;
939                 }
940
941                 /* Non-directory */
942                 dtype = ce_to_dtype(ce);
943                 ret = is_excluded_from_list(ce->name, ce_namelen(ce),
944                                             name, &dtype, el);
945                 if (ret < 0)
946                         ret = defval;
947                 if (ret > 0)
948                         ce->ce_flags &= ~clear_mask;
949                 cache++;
950         }
951         return nr - (cache_end - cache);
952 }
953
954 static int clear_ce_flags(struct cache_entry **cache, int nr,
955                             int select_mask, int clear_mask,
956                             struct exclude_list *el)
957 {
958         char prefix[PATH_MAX];
959         return clear_ce_flags_1(cache, nr,
960                                 prefix, 0,
961                                 select_mask, clear_mask,
962                                 el, 0);
963 }
964
965 /*
966  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
967  */
968 static void mark_new_skip_worktree(struct exclude_list *el,
969                                    struct index_state *the_index,
970                                    int select_flag, int skip_wt_flag)
971 {
972         int i;
973
974         /*
975          * 1. Pretend the narrowest worktree: only unmerged entries
976          * are checked out
977          */
978         for (i = 0; i < the_index->cache_nr; i++) {
979                 struct cache_entry *ce = the_index->cache[i];
980
981                 if (select_flag && !(ce->ce_flags & select_flag))
982                         continue;
983
984                 if (!ce_stage(ce))
985                         ce->ce_flags |= skip_wt_flag;
986                 else
987                         ce->ce_flags &= ~skip_wt_flag;
988         }
989
990         /*
991          * 2. Widen worktree according to sparse-checkout file.
992          * Matched entries will have skip_wt_flag cleared (i.e. "in")
993          */
994         clear_ce_flags(the_index->cache, the_index->cache_nr,
995                        select_flag, skip_wt_flag, el);
996 }
997
998 static int verify_absent(struct cache_entry *, enum unpack_trees_error_types, struct unpack_trees_options *);
999 /*
1000  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1001  * resulting index, -2 on failure to reflect the changes to the work tree.
1002  *
1003  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1004  */
1005 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1006 {
1007         int i, ret;
1008         static struct cache_entry *dfc;
1009         struct exclude_list el;
1010
1011         if (len > MAX_UNPACK_TREES)
1012                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1013         memset(&state, 0, sizeof(state));
1014         state.base_dir = "";
1015         state.force = 1;
1016         state.quiet = 1;
1017         state.refresh_cache = 1;
1018
1019         memset(&el, 0, sizeof(el));
1020         if (!core_apply_sparse_checkout || !o->update)
1021                 o->skip_sparse_checkout = 1;
1022         if (!o->skip_sparse_checkout) {
1023                 if (add_excludes_from_file_to_list(git_path("info/sparse-checkout"), "", 0, &el, 0) < 0)
1024                         o->skip_sparse_checkout = 1;
1025                 else
1026                         o->el = &el;
1027         }
1028
1029         if (o->dir) {
1030                 o->path_exclude_check = xmalloc(sizeof(struct path_exclude_check));
1031                 path_exclude_check_init(o->path_exclude_check, o->dir);
1032         }
1033         memset(&o->result, 0, sizeof(o->result));
1034         o->result.initialized = 1;
1035         o->result.timestamp.sec = o->src_index->timestamp.sec;
1036         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1037         o->result.version = o->src_index->version;
1038         o->merge_size = len;
1039         mark_all_ce_unused(o->src_index);
1040
1041         /*
1042          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1043          */
1044         if (!o->skip_sparse_checkout)
1045                 mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1046
1047         if (!dfc)
1048                 dfc = xcalloc(1, cache_entry_size(0));
1049         o->df_conflict_entry = dfc;
1050
1051         if (len) {
1052                 const char *prefix = o->prefix ? o->prefix : "";
1053                 struct traverse_info info;
1054
1055                 setup_traverse_info(&info, prefix);
1056                 info.fn = unpack_callback;
1057                 info.data = o;
1058                 info.show_all_errors = o->show_all_errors;
1059                 info.pathspec = o->pathspec;
1060
1061                 if (o->prefix) {
1062                         /*
1063                          * Unpack existing index entries that sort before the
1064                          * prefix the tree is spliced into.  Note that o->merge
1065                          * is always true in this case.
1066                          */
1067                         while (1) {
1068                                 struct cache_entry *ce = next_cache_entry(o);
1069                                 if (!ce)
1070                                         break;
1071                                 if (ce_in_traverse_path(ce, &info))
1072                                         break;
1073                                 if (unpack_index_entry(ce, o) < 0)
1074                                         goto return_failed;
1075                         }
1076                 }
1077
1078                 if (traverse_trees(len, t, &info) < 0)
1079                         goto return_failed;
1080         }
1081
1082         /* Any left-over entries in the index? */
1083         if (o->merge) {
1084                 while (1) {
1085                         struct cache_entry *ce = next_cache_entry(o);
1086                         if (!ce)
1087                                 break;
1088                         if (unpack_index_entry(ce, o) < 0)
1089                                 goto return_failed;
1090                 }
1091         }
1092         mark_all_ce_unused(o->src_index);
1093
1094         if (o->trivial_merges_only && o->nontrivial_merge) {
1095                 ret = unpack_failed(o, "Merge requires file-level merging");
1096                 goto done;
1097         }
1098
1099         if (!o->skip_sparse_checkout) {
1100                 int empty_worktree = 1;
1101
1102                 /*
1103                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1104                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1105                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1106                  */
1107                 mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1108
1109                 ret = 0;
1110                 for (i = 0; i < o->result.cache_nr; i++) {
1111                         struct cache_entry *ce = o->result.cache[i];
1112
1113                         /*
1114                          * Entries marked with CE_ADDED in merged_entry() do not have
1115                          * verify_absent() check (the check is effectively disabled
1116                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1117                          *
1118                          * Do the real check now because we have had
1119                          * correct CE_NEW_SKIP_WORKTREE
1120                          */
1121                         if (ce->ce_flags & CE_ADDED &&
1122                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1123                                 if (!o->show_all_errors)
1124                                         goto return_failed;
1125                                 ret = -1;
1126                         }
1127
1128                         if (apply_sparse_checkout(ce, o)) {
1129                                 if (!o->show_all_errors)
1130                                         goto return_failed;
1131                                 ret = -1;
1132                         }
1133                         if (!ce_skip_worktree(ce))
1134                                 empty_worktree = 0;
1135
1136                 }
1137                 if (ret < 0)
1138                         goto return_failed;
1139                 /*
1140                  * Sparse checkout is meant to narrow down checkout area
1141                  * but it does not make sense to narrow down to empty working
1142                  * tree. This is usually a mistake in sparse checkout rules.
1143                  * Do not allow users to do that.
1144                  */
1145                 if (o->result.cache_nr && empty_worktree) {
1146                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1147                         goto done;
1148                 }
1149         }
1150
1151         o->src_index = NULL;
1152         ret = check_updates(o) ? (-2) : 0;
1153         if (o->dst_index)
1154                 *o->dst_index = o->result;
1155
1156 done:
1157         clear_exclude_list(&el);
1158         if (o->path_exclude_check) {
1159                 path_exclude_check_clear(o->path_exclude_check);
1160                 free(o->path_exclude_check);
1161         }
1162         return ret;
1163
1164 return_failed:
1165         if (o->show_all_errors)
1166                 display_error_msgs(o);
1167         mark_all_ce_unused(o->src_index);
1168         ret = unpack_failed(o, NULL);
1169         if (o->exiting_early)
1170                 ret = 0;
1171         goto done;
1172 }
1173
1174 /* Here come the merge functions */
1175
1176 static int reject_merge(struct cache_entry *ce, struct unpack_trees_options *o)
1177 {
1178         return add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1179 }
1180
1181 static int same(struct cache_entry *a, struct cache_entry *b)
1182 {
1183         if (!!a != !!b)
1184                 return 0;
1185         if (!a && !b)
1186                 return 1;
1187         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1188                 return 0;
1189         return a->ce_mode == b->ce_mode &&
1190                !hashcmp(a->sha1, b->sha1);
1191 }
1192
1193
1194 /*
1195  * When a CE gets turned into an unmerged entry, we
1196  * want it to be up-to-date
1197  */
1198 static int verify_uptodate_1(struct cache_entry *ce,
1199                                    struct unpack_trees_options *o,
1200                                    enum unpack_trees_error_types error_type)
1201 {
1202         struct stat st;
1203
1204         if (o->index_only)
1205                 return 0;
1206
1207         /*
1208          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1209          * if this entry is truly up-to-date because this file may be
1210          * overwritten.
1211          */
1212         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1213                 ; /* keep checking */
1214         else if (o->reset || ce_uptodate(ce))
1215                 return 0;
1216
1217         if (!lstat(ce->name, &st)) {
1218                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1219                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1220                 if (!changed)
1221                         return 0;
1222                 /*
1223                  * NEEDSWORK: the current default policy is to allow
1224                  * submodule to be out of sync wrt the superproject
1225                  * index.  This needs to be tightened later for
1226                  * submodules that are marked to be automatically
1227                  * checked out.
1228                  */
1229                 if (S_ISGITLINK(ce->ce_mode))
1230                         return 0;
1231                 errno = 0;
1232         }
1233         if (errno == ENOENT)
1234                 return 0;
1235         return o->gently ? -1 :
1236                 add_rejected_path(o, error_type, ce->name);
1237 }
1238
1239 static int verify_uptodate(struct cache_entry *ce,
1240                            struct unpack_trees_options *o)
1241 {
1242         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1243                 return 0;
1244         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1245 }
1246
1247 static int verify_uptodate_sparse(struct cache_entry *ce,
1248                                   struct unpack_trees_options *o)
1249 {
1250         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1251 }
1252
1253 static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
1254 {
1255         if (ce)
1256                 cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
1257 }
1258
1259 /*
1260  * Check that checking out ce->sha1 in subdir ce->name is not
1261  * going to overwrite any working files.
1262  *
1263  * Currently, git does not checkout subprojects during a superproject
1264  * checkout, so it is not going to overwrite anything.
1265  */
1266 static int verify_clean_submodule(struct cache_entry *ce,
1267                                       enum unpack_trees_error_types error_type,
1268                                       struct unpack_trees_options *o)
1269 {
1270         return 0;
1271 }
1272
1273 static int verify_clean_subdirectory(struct cache_entry *ce,
1274                                       enum unpack_trees_error_types error_type,
1275                                       struct unpack_trees_options *o)
1276 {
1277         /*
1278          * we are about to extract "ce->name"; we would not want to lose
1279          * anything in the existing directory there.
1280          */
1281         int namelen;
1282         int i;
1283         struct dir_struct d;
1284         char *pathbuf;
1285         int cnt = 0;
1286         unsigned char sha1[20];
1287
1288         if (S_ISGITLINK(ce->ce_mode) &&
1289             resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
1290                 /* If we are not going to update the submodule, then
1291                  * we don't care.
1292                  */
1293                 if (!hashcmp(sha1, ce->sha1))
1294                         return 0;
1295                 return verify_clean_submodule(ce, error_type, o);
1296         }
1297
1298         /*
1299          * First let's make sure we do not have a local modification
1300          * in that directory.
1301          */
1302         namelen = ce_namelen(ce);
1303         for (i = locate_in_src_index(ce, o);
1304              i < o->src_index->cache_nr;
1305              i++) {
1306                 struct cache_entry *ce2 = o->src_index->cache[i];
1307                 int len = ce_namelen(ce2);
1308                 if (len < namelen ||
1309                     strncmp(ce->name, ce2->name, namelen) ||
1310                     ce2->name[namelen] != '/')
1311                         break;
1312                 /*
1313                  * ce2->name is an entry in the subdirectory to be
1314                  * removed.
1315                  */
1316                 if (!ce_stage(ce2)) {
1317                         if (verify_uptodate(ce2, o))
1318                                 return -1;
1319                         add_entry(o, ce2, CE_REMOVE, 0);
1320                         mark_ce_used(ce2, o);
1321                 }
1322                 cnt++;
1323         }
1324
1325         /*
1326          * Then we need to make sure that we do not lose a locally
1327          * present file that is not ignored.
1328          */
1329         pathbuf = xmalloc(namelen + 2);
1330         memcpy(pathbuf, ce->name, namelen);
1331         strcpy(pathbuf+namelen, "/");
1332
1333         memset(&d, 0, sizeof(d));
1334         if (o->dir)
1335                 d.exclude_per_dir = o->dir->exclude_per_dir;
1336         i = read_directory(&d, pathbuf, namelen+1, NULL);
1337         if (i)
1338                 return o->gently ? -1 :
1339                         add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1340         free(pathbuf);
1341         return cnt;
1342 }
1343
1344 /*
1345  * This gets called when there was no index entry for the tree entry 'dst',
1346  * but we found a file in the working tree that 'lstat()' said was fine,
1347  * and we're on a case-insensitive filesystem.
1348  *
1349  * See if we can find a case-insensitive match in the index that also
1350  * matches the stat information, and assume it's that other file!
1351  */
1352 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1353 {
1354         struct cache_entry *src;
1355
1356         src = index_name_exists(o->src_index, name, len, 1);
1357         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1358 }
1359
1360 static int check_ok_to_remove(const char *name, int len, int dtype,
1361                               struct cache_entry *ce, struct stat *st,
1362                               enum unpack_trees_error_types error_type,
1363                               struct unpack_trees_options *o)
1364 {
1365         struct cache_entry *result;
1366
1367         /*
1368          * It may be that the 'lstat()' succeeded even though
1369          * target 'ce' was absent, because there is an old
1370          * entry that is different only in case..
1371          *
1372          * Ignore that lstat() if it matches.
1373          */
1374         if (ignore_case && icase_exists(o, name, len, st))
1375                 return 0;
1376
1377         if (o->dir &&
1378             is_path_excluded(o->path_exclude_check, name, -1, &dtype))
1379                 /*
1380                  * ce->name is explicitly excluded, so it is Ok to
1381                  * overwrite it.
1382                  */
1383                 return 0;
1384         if (S_ISDIR(st->st_mode)) {
1385                 /*
1386                  * We are checking out path "foo" and
1387                  * found "foo/." in the working tree.
1388                  * This is tricky -- if we have modified
1389                  * files that are in "foo/" we would lose
1390                  * them.
1391                  */
1392                 if (verify_clean_subdirectory(ce, error_type, o) < 0)
1393                         return -1;
1394                 return 0;
1395         }
1396
1397         /*
1398          * The previous round may already have decided to
1399          * delete this path, which is in a subdirectory that
1400          * is being replaced with a blob.
1401          */
1402         result = index_name_exists(&o->result, name, len, 0);
1403         if (result) {
1404                 if (result->ce_flags & CE_REMOVE)
1405                         return 0;
1406         }
1407
1408         return o->gently ? -1 :
1409                 add_rejected_path(o, error_type, name);
1410 }
1411
1412 /*
1413  * We do not want to remove or overwrite a working tree file that
1414  * is not tracked, unless it is ignored.
1415  */
1416 static int verify_absent_1(struct cache_entry *ce,
1417                                  enum unpack_trees_error_types error_type,
1418                                  struct unpack_trees_options *o)
1419 {
1420         int len;
1421         struct stat st;
1422
1423         if (o->index_only || o->reset || !o->update)
1424                 return 0;
1425
1426         len = check_leading_path(ce->name, ce_namelen(ce));
1427         if (!len)
1428                 return 0;
1429         else if (len > 0) {
1430                 char path[PATH_MAX + 1];
1431                 memcpy(path, ce->name, len);
1432                 path[len] = 0;
1433                 if (lstat(path, &st))
1434                         return error("cannot stat '%s': %s", path,
1435                                         strerror(errno));
1436
1437                 return check_ok_to_remove(path, len, DT_UNKNOWN, NULL, &st,
1438                                 error_type, o);
1439         } else if (lstat(ce->name, &st)) {
1440                 if (errno != ENOENT)
1441                         return error("cannot stat '%s': %s", ce->name,
1442                                      strerror(errno));
1443                 return 0;
1444         } else {
1445                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1446                                           ce_to_dtype(ce), ce, &st,
1447                                           error_type, o);
1448         }
1449 }
1450
1451 static int verify_absent(struct cache_entry *ce,
1452                          enum unpack_trees_error_types error_type,
1453                          struct unpack_trees_options *o)
1454 {
1455         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1456                 return 0;
1457         return verify_absent_1(ce, error_type, o);
1458 }
1459
1460 static int verify_absent_sparse(struct cache_entry *ce,
1461                          enum unpack_trees_error_types error_type,
1462                          struct unpack_trees_options *o)
1463 {
1464         enum unpack_trees_error_types orphaned_error = error_type;
1465         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1466                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1467
1468         return verify_absent_1(ce, orphaned_error, o);
1469 }
1470
1471 static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
1472                 struct unpack_trees_options *o)
1473 {
1474         int update = CE_UPDATE;
1475
1476         if (!old) {
1477                 /*
1478                  * New index entries. In sparse checkout, the following
1479                  * verify_absent() will be delayed until after
1480                  * traverse_trees() finishes in unpack_trees(), then:
1481                  *
1482                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1483                  *  - verify_absent() be called again, this time with
1484                  *    correct CE_NEW_SKIP_WORKTREE
1485                  *
1486                  * verify_absent() call here does nothing in sparse
1487                  * checkout (i.e. o->skip_sparse_checkout == 0)
1488                  */
1489                 update |= CE_ADDED;
1490                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1491
1492                 if (verify_absent(merge, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
1493                         return -1;
1494                 invalidate_ce_path(merge, o);
1495         } else if (!(old->ce_flags & CE_CONFLICTED)) {
1496                 /*
1497                  * See if we can re-use the old CE directly?
1498                  * That way we get the uptodate stat info.
1499                  *
1500                  * This also removes the UPDATE flag on a match; otherwise
1501                  * we will end up overwriting local changes in the work tree.
1502                  */
1503                 if (same(old, merge)) {
1504                         copy_cache_entry(merge, old);
1505                         update = 0;
1506                 } else {
1507                         if (verify_uptodate(old, o))
1508                                 return -1;
1509                         /* Migrate old flags over */
1510                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1511                         invalidate_ce_path(old, o);
1512                 }
1513         } else {
1514                 /*
1515                  * Previously unmerged entry left as an existence
1516                  * marker by read_index_unmerged();
1517                  */
1518                 invalidate_ce_path(old, o);
1519         }
1520
1521         add_entry(o, merge, update, CE_STAGEMASK);
1522         return 1;
1523 }
1524
1525 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
1526                 struct unpack_trees_options *o)
1527 {
1528         /* Did it exist in the index? */
1529         if (!old) {
1530                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1531                         return -1;
1532                 return 0;
1533         }
1534         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1535                 return -1;
1536         add_entry(o, ce, CE_REMOVE, 0);
1537         invalidate_ce_path(ce, o);
1538         return 1;
1539 }
1540
1541 static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
1542 {
1543         add_entry(o, ce, 0, 0);
1544         return 1;
1545 }
1546
1547 #if DBRT_DEBUG
1548 static void show_stage_entry(FILE *o,
1549                              const char *label, const struct cache_entry *ce)
1550 {
1551         if (!ce)
1552                 fprintf(o, "%s (missing)\n", label);
1553         else
1554                 fprintf(o, "%s%06o %s %d\t%s\n",
1555                         label,
1556                         ce->ce_mode,
1557                         sha1_to_hex(ce->sha1),
1558                         ce_stage(ce),
1559                         ce->name);
1560 }
1561 #endif
1562
1563 int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
1564 {
1565         struct cache_entry *index;
1566         struct cache_entry *head;
1567         struct cache_entry *remote = stages[o->head_idx + 1];
1568         int count;
1569         int head_match = 0;
1570         int remote_match = 0;
1571
1572         int df_conflict_head = 0;
1573         int df_conflict_remote = 0;
1574
1575         int any_anc_missing = 0;
1576         int no_anc_exists = 1;
1577         int i;
1578
1579         for (i = 1; i < o->head_idx; i++) {
1580                 if (!stages[i] || stages[i] == o->df_conflict_entry)
1581                         any_anc_missing = 1;
1582                 else
1583                         no_anc_exists = 0;
1584         }
1585
1586         index = stages[0];
1587         head = stages[o->head_idx];
1588
1589         if (head == o->df_conflict_entry) {
1590                 df_conflict_head = 1;
1591                 head = NULL;
1592         }
1593
1594         if (remote == o->df_conflict_entry) {
1595                 df_conflict_remote = 1;
1596                 remote = NULL;
1597         }
1598
1599         /*
1600          * First, if there's a #16 situation, note that to prevent #13
1601          * and #14.
1602          */
1603         if (!same(remote, head)) {
1604                 for (i = 1; i < o->head_idx; i++) {
1605                         if (same(stages[i], head)) {
1606                                 head_match = i;
1607                         }
1608                         if (same(stages[i], remote)) {
1609                                 remote_match = i;
1610                         }
1611                 }
1612         }
1613
1614         /*
1615          * We start with cases where the index is allowed to match
1616          * something other than the head: #14(ALT) and #2ALT, where it
1617          * is permitted to match the result instead.
1618          */
1619         /* #14, #14ALT, #2ALT */
1620         if (remote && !df_conflict_head && head_match && !remote_match) {
1621                 if (index && !same(index, remote) && !same(index, head))
1622                         return o->gently ? -1 : reject_merge(index, o);
1623                 return merged_entry(remote, index, o);
1624         }
1625         /*
1626          * If we have an entry in the index cache, then we want to
1627          * make sure that it matches head.
1628          */
1629         if (index && !same(index, head))
1630                 return o->gently ? -1 : reject_merge(index, o);
1631
1632         if (head) {
1633                 /* #5ALT, #15 */
1634                 if (same(head, remote))
1635                         return merged_entry(head, index, o);
1636                 /* #13, #3ALT */
1637                 if (!df_conflict_remote && remote_match && !head_match)
1638                         return merged_entry(head, index, o);
1639         }
1640
1641         /* #1 */
1642         if (!head && !remote && any_anc_missing)
1643                 return 0;
1644
1645         /*
1646          * Under the "aggressive" rule, we resolve mostly trivial
1647          * cases that we historically had git-merge-one-file resolve.
1648          */
1649         if (o->aggressive) {
1650                 int head_deleted = !head;
1651                 int remote_deleted = !remote;
1652                 struct cache_entry *ce = NULL;
1653
1654                 if (index)
1655                         ce = index;
1656                 else if (head)
1657                         ce = head;
1658                 else if (remote)
1659                         ce = remote;
1660                 else {
1661                         for (i = 1; i < o->head_idx; i++) {
1662                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
1663                                         ce = stages[i];
1664                                         break;
1665                                 }
1666                         }
1667                 }
1668
1669                 /*
1670                  * Deleted in both.
1671                  * Deleted in one and unchanged in the other.
1672                  */
1673                 if ((head_deleted && remote_deleted) ||
1674                     (head_deleted && remote && remote_match) ||
1675                     (remote_deleted && head && head_match)) {
1676                         if (index)
1677                                 return deleted_entry(index, index, o);
1678                         if (ce && !head_deleted) {
1679                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1680                                         return -1;
1681                         }
1682                         return 0;
1683                 }
1684                 /*
1685                  * Added in both, identically.
1686                  */
1687                 if (no_anc_exists && head && remote && same(head, remote))
1688                         return merged_entry(head, index, o);
1689
1690         }
1691
1692         /* Below are "no merge" cases, which require that the index be
1693          * up-to-date to avoid the files getting overwritten with
1694          * conflict resolution files.
1695          */
1696         if (index) {
1697                 if (verify_uptodate(index, o))
1698                         return -1;
1699         }
1700
1701         o->nontrivial_merge = 1;
1702
1703         /* #2, #3, #4, #6, #7, #9, #10, #11. */
1704         count = 0;
1705         if (!head_match || !remote_match) {
1706                 for (i = 1; i < o->head_idx; i++) {
1707                         if (stages[i] && stages[i] != o->df_conflict_entry) {
1708                                 keep_entry(stages[i], o);
1709                                 count++;
1710                                 break;
1711                         }
1712                 }
1713         }
1714 #if DBRT_DEBUG
1715         else {
1716                 fprintf(stderr, "read-tree: warning #16 detected\n");
1717                 show_stage_entry(stderr, "head   ", stages[head_match]);
1718                 show_stage_entry(stderr, "remote ", stages[remote_match]);
1719         }
1720 #endif
1721         if (head) { count += keep_entry(head, o); }
1722         if (remote) { count += keep_entry(remote, o); }
1723         return count;
1724 }
1725
1726 /*
1727  * Two-way merge.
1728  *
1729  * The rule is to "carry forward" what is in the index without losing
1730  * information across a "fast-forward", favoring a successful merge
1731  * over a merge failure when it makes sense.  For details of the
1732  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
1733  *
1734  */
1735 int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1736 {
1737         struct cache_entry *current = src[0];
1738         struct cache_entry *oldtree = src[1];
1739         struct cache_entry *newtree = src[2];
1740
1741         if (o->merge_size != 2)
1742                 return error("Cannot do a twoway merge of %d trees",
1743                              o->merge_size);
1744
1745         if (oldtree == o->df_conflict_entry)
1746                 oldtree = NULL;
1747         if (newtree == o->df_conflict_entry)
1748                 newtree = NULL;
1749
1750         if (current) {
1751                 if ((!oldtree && !newtree) || /* 4 and 5 */
1752                     (!oldtree && newtree &&
1753                      same(current, newtree)) || /* 6 and 7 */
1754                     (oldtree && newtree &&
1755                      same(oldtree, newtree)) || /* 14 and 15 */
1756                     (oldtree && newtree &&
1757                      !same(oldtree, newtree) && /* 18 and 19 */
1758                      same(current, newtree))) {
1759                         return keep_entry(current, o);
1760                 }
1761                 else if (oldtree && !newtree && same(current, oldtree)) {
1762                         /* 10 or 11 */
1763                         return deleted_entry(oldtree, current, o);
1764                 }
1765                 else if (oldtree && newtree &&
1766                          same(current, oldtree) && !same(current, newtree)) {
1767                         /* 20 or 21 */
1768                         return merged_entry(newtree, current, o);
1769                 }
1770                 else {
1771                         /* all other failures */
1772                         if (oldtree)
1773                                 return o->gently ? -1 : reject_merge(oldtree, o);
1774                         if (current)
1775                                 return o->gently ? -1 : reject_merge(current, o);
1776                         if (newtree)
1777                                 return o->gently ? -1 : reject_merge(newtree, o);
1778                         return -1;
1779                 }
1780         }
1781         else if (newtree) {
1782                 if (oldtree && !o->initial_checkout) {
1783                         /*
1784                          * deletion of the path was staged;
1785                          */
1786                         if (same(oldtree, newtree))
1787                                 return 1;
1788                         return reject_merge(oldtree, o);
1789                 }
1790                 return merged_entry(newtree, current, o);
1791         }
1792         return deleted_entry(oldtree, current, o);
1793 }
1794
1795 /*
1796  * Bind merge.
1797  *
1798  * Keep the index entries at stage0, collapse stage1 but make sure
1799  * stage0 does not have anything there.
1800  */
1801 int bind_merge(struct cache_entry **src,
1802                 struct unpack_trees_options *o)
1803 {
1804         struct cache_entry *old = src[0];
1805         struct cache_entry *a = src[1];
1806
1807         if (o->merge_size != 1)
1808                 return error("Cannot do a bind merge of %d trees",
1809                              o->merge_size);
1810         if (a && old)
1811                 return o->gently ? -1 :
1812                         error(ERRORMSG(o, ERROR_BIND_OVERLAP), a->name, old->name);
1813         if (!a)
1814                 return keep_entry(old, o);
1815         else
1816                 return merged_entry(a, NULL, o);
1817 }
1818
1819 /*
1820  * One-way merge.
1821  *
1822  * The rule is:
1823  * - take the stat information from stage0, take the data from stage1
1824  */
1825 int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1826 {
1827         struct cache_entry *old = src[0];
1828         struct cache_entry *a = src[1];
1829
1830         if (o->merge_size != 1)
1831                 return error("Cannot do a oneway merge of %d trees",
1832                              o->merge_size);
1833
1834         if (!a || a == o->df_conflict_entry)
1835                 return deleted_entry(old, old, o);
1836
1837         if (old && same(old, a)) {
1838                 int update = 0;
1839                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
1840                         struct stat st;
1841                         if (lstat(old->name, &st) ||
1842                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
1843                                 update |= CE_UPDATE;
1844                 }
1845                 add_entry(o, old, update, 0);
1846                 return 0;
1847         }
1848         return merged_entry(a, old, o);
1849 }