Merge branch 'js/larger-timestamps'
[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 #include "split-index.h"
12 #include "dir.h"
13 #include "submodule.h"
14 #include "submodule-config.h"
15
16 /*
17  * Error messages expected by scripts out of plumbing commands such as
18  * read-tree.  Non-scripted Porcelain is not required to use these messages
19  * and in fact are encouraged to reword them to better suit their particular
20  * situation better.  See how "git checkout" and "git merge" replaces
21  * them using setup_unpack_trees_porcelain(), for example.
22  */
23 static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
24         /* ERROR_WOULD_OVERWRITE */
25         "Entry '%s' would be overwritten by merge. Cannot merge.",
26
27         /* ERROR_NOT_UPTODATE_FILE */
28         "Entry '%s' not uptodate. Cannot merge.",
29
30         /* ERROR_NOT_UPTODATE_DIR */
31         "Updating '%s' would lose untracked files in it",
32
33         /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
34         "Untracked working tree file '%s' would be overwritten by merge.",
35
36         /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
37         "Untracked working tree file '%s' would be removed by merge.",
38
39         /* ERROR_BIND_OVERLAP */
40         "Entry '%s' overlaps with '%s'.  Cannot bind.",
41
42         /* ERROR_SPARSE_NOT_UPTODATE_FILE */
43         "Entry '%s' not uptodate. Cannot update sparse checkout.",
44
45         /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
46         "Working tree file '%s' would be overwritten by sparse checkout update.",
47
48         /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
49         "Working tree file '%s' would be removed by sparse checkout update.",
50
51         /* ERROR_WOULD_LOSE_SUBMODULE */
52         "Submodule '%s' cannot checkout new HEAD.",
53 };
54
55 #define ERRORMSG(o,type) \
56         ( ((o) && (o)->msgs[(type)]) \
57           ? ((o)->msgs[(type)])      \
58           : (unpack_plumbing_errors[(type)]) )
59
60 static const char *super_prefixed(const char *path)
61 {
62         /*
63          * It is necessary and sufficient to have two static buffers
64          * here, as the return value of this function is fed to
65          * error() using the unpack_*_errors[] templates we see above.
66          */
67         static struct strbuf buf[2] = {STRBUF_INIT, STRBUF_INIT};
68         static int super_prefix_len = -1;
69         static unsigned idx = ARRAY_SIZE(buf) - 1;
70
71         if (super_prefix_len < 0) {
72                 const char *super_prefix = get_super_prefix();
73                 if (!super_prefix) {
74                         super_prefix_len = 0;
75                 } else {
76                         int i;
77                         for (i = 0; i < ARRAY_SIZE(buf); i++)
78                                 strbuf_addstr(&buf[i], super_prefix);
79                         super_prefix_len = buf[0].len;
80                 }
81         }
82
83         if (!super_prefix_len)
84                 return path;
85
86         if (++idx >= ARRAY_SIZE(buf))
87                 idx = 0;
88
89         strbuf_setlen(&buf[idx], super_prefix_len);
90         strbuf_addstr(&buf[idx], path);
91
92         return buf[idx].buf;
93 }
94
95 void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
96                                   const char *cmd)
97 {
98         int i;
99         const char **msgs = opts->msgs;
100         const char *msg;
101
102         if (!strcmp(cmd, "checkout"))
103                 msg = advice_commit_before_merge
104                       ? _("Your local changes to the following files would be overwritten by checkout:\n%%s"
105                           "Please commit your changes or stash them before you switch branches.")
106                       : _("Your local changes to the following files would be overwritten by checkout:\n%%s");
107         else if (!strcmp(cmd, "merge"))
108                 msg = advice_commit_before_merge
109                       ? _("Your local changes to the following files would be overwritten by merge:\n%%s"
110                           "Please commit your changes or stash them before you merge.")
111                       : _("Your local changes to the following files would be overwritten by merge:\n%%s");
112         else
113                 msg = advice_commit_before_merge
114                       ? _("Your local changes to the following files would be overwritten by %s:\n%%s"
115                           "Please commit your changes or stash them before you %s.")
116                       : _("Your local changes to the following files would be overwritten by %s:\n%%s");
117         msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
118                 xstrfmt(msg, cmd, cmd);
119
120         msgs[ERROR_NOT_UPTODATE_DIR] =
121                 _("Updating the following directories would lose untracked files in them:\n%s");
122
123         if (!strcmp(cmd, "checkout"))
124                 msg = advice_commit_before_merge
125                       ? _("The following untracked working tree files would be removed by checkout:\n%%s"
126                           "Please move or remove them before you switch branches.")
127                       : _("The following untracked working tree files would be removed by checkout:\n%%s");
128         else if (!strcmp(cmd, "merge"))
129                 msg = advice_commit_before_merge
130                       ? _("The following untracked working tree files would be removed by merge:\n%%s"
131                           "Please move or remove them before you merge.")
132                       : _("The following untracked working tree files would be removed by merge:\n%%s");
133         else
134                 msg = advice_commit_before_merge
135                       ? _("The following untracked working tree files would be removed by %s:\n%%s"
136                           "Please move or remove them before you %s.")
137                       : _("The following untracked working tree files would be removed by %s:\n%%s");
138         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = xstrfmt(msg, cmd, cmd);
139
140         if (!strcmp(cmd, "checkout"))
141                 msg = advice_commit_before_merge
142                       ? _("The following untracked working tree files would be overwritten by checkout:\n%%s"
143                           "Please move or remove them before you switch branches.")
144                       : _("The following untracked working tree files would be overwritten by checkout:\n%%s");
145         else if (!strcmp(cmd, "merge"))
146                 msg = advice_commit_before_merge
147                       ? _("The following untracked working tree files would be overwritten by merge:\n%%s"
148                           "Please move or remove them before you merge.")
149                       : _("The following untracked working tree files would be overwritten by merge:\n%%s");
150         else
151                 msg = advice_commit_before_merge
152                       ? _("The following untracked working tree files would be overwritten by %s:\n%%s"
153                           "Please move or remove them before you %s.")
154                       : _("The following untracked working tree files would be overwritten by %s:\n%%s");
155         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = xstrfmt(msg, cmd, cmd);
156
157         /*
158          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
159          * cannot easily display it as a list.
160          */
161         msgs[ERROR_BIND_OVERLAP] = _("Entry '%s' overlaps with '%s'.  Cannot bind.");
162
163         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
164                 _("Cannot update sparse checkout: the following entries are not up-to-date:\n%s");
165         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
166                 _("The following working tree files would be overwritten by sparse checkout update:\n%s");
167         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
168                 _("The following working tree files would be removed by sparse checkout update:\n%s");
169         msgs[ERROR_WOULD_LOSE_SUBMODULE] =
170                 _("Cannot update submodule:\n%s");
171
172         opts->show_all_errors = 1;
173         /* rejected paths may not have a static buffer */
174         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
175                 opts->unpack_rejects[i].strdup_strings = 1;
176 }
177
178 static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
179                          unsigned int set, unsigned int clear)
180 {
181         clear |= CE_HASHED;
182
183         if (set & CE_REMOVE)
184                 set |= CE_WT_REMOVE;
185
186         ce->ce_flags = (ce->ce_flags & ~clear) | set;
187         return add_index_entry(&o->result, ce,
188                                ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
189 }
190
191 static struct cache_entry *dup_entry(const struct cache_entry *ce)
192 {
193         unsigned int size = ce_size(ce);
194         struct cache_entry *new = xmalloc(size);
195
196         memcpy(new, ce, size);
197         return new;
198 }
199
200 static void add_entry(struct unpack_trees_options *o,
201                       const struct cache_entry *ce,
202                       unsigned int set, unsigned int clear)
203 {
204         do_add_entry(o, dup_entry(ce), set, clear);
205 }
206
207 /*
208  * add error messages on path <path>
209  * corresponding to the type <e> with the message <msg>
210  * indicating if it should be display in porcelain or not
211  */
212 static int add_rejected_path(struct unpack_trees_options *o,
213                              enum unpack_trees_error_types e,
214                              const char *path)
215 {
216         if (!o->show_all_errors)
217                 return error(ERRORMSG(o, e), super_prefixed(path));
218
219         /*
220          * Otherwise, insert in a list for future display by
221          * display_error_msgs()
222          */
223         string_list_append(&o->unpack_rejects[e], path);
224         return -1;
225 }
226
227 /*
228  * display all the error messages stored in a nice way
229  */
230 static void display_error_msgs(struct unpack_trees_options *o)
231 {
232         int e, i;
233         int something_displayed = 0;
234         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
235                 struct string_list *rejects = &o->unpack_rejects[e];
236                 if (rejects->nr > 0) {
237                         struct strbuf path = STRBUF_INIT;
238                         something_displayed = 1;
239                         for (i = 0; i < rejects->nr; i++)
240                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
241                         error(ERRORMSG(o, e), super_prefixed(path.buf));
242                         strbuf_release(&path);
243                 }
244                 string_list_clear(rejects, 0);
245         }
246         if (something_displayed)
247                 fprintf(stderr, _("Aborting\n"));
248 }
249
250 static int check_submodule_move_head(const struct cache_entry *ce,
251                                      const char *old_id,
252                                      const char *new_id,
253                                      struct unpack_trees_options *o)
254 {
255         const struct submodule *sub = submodule_from_ce(ce);
256         if (!sub)
257                 return 0;
258
259         switch (sub->update_strategy.type) {
260         case SM_UPDATE_UNSPECIFIED:
261         case SM_UPDATE_CHECKOUT:
262                 if (submodule_move_head(ce->name, old_id, new_id, SUBMODULE_MOVE_HEAD_DRY_RUN))
263                         return o->gently ? -1 :
264                                 add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
265                 return 0;
266         case SM_UPDATE_NONE:
267                 return 0;
268         case SM_UPDATE_REBASE:
269         case SM_UPDATE_MERGE:
270         case SM_UPDATE_COMMAND:
271         default:
272                 warning(_("submodule update strategy not supported for submodule '%s'"), ce->name);
273                 return -1;
274         }
275 }
276
277 static void reload_gitmodules_file(struct index_state *index,
278                                    struct checkout *state)
279 {
280         int i;
281         for (i = 0; i < index->cache_nr; i++) {
282                 struct cache_entry *ce = index->cache[i];
283                 if (ce->ce_flags & CE_UPDATE) {
284                         int r = strcmp(ce->name, ".gitmodules");
285                         if (r < 0)
286                                 continue;
287                         else if (r == 0) {
288                                 submodule_free();
289                                 checkout_entry(ce, state, NULL);
290                                 gitmodules_config();
291                                 git_config(submodule_config, NULL);
292                         } else
293                                 break;
294                 }
295         }
296 }
297
298 /*
299  * Unlink the last component and schedule the leading directories for
300  * removal, such that empty directories get removed.
301  */
302 static void unlink_entry(const struct cache_entry *ce)
303 {
304         const struct submodule *sub = submodule_from_ce(ce);
305         if (sub) {
306                 switch (sub->update_strategy.type) {
307                 case SM_UPDATE_UNSPECIFIED:
308                 case SM_UPDATE_CHECKOUT:
309                 case SM_UPDATE_REBASE:
310                 case SM_UPDATE_MERGE:
311                         submodule_move_head(ce->name, "HEAD", NULL,
312                                             SUBMODULE_MOVE_HEAD_FORCE);
313                         break;
314                 case SM_UPDATE_NONE:
315                 case SM_UPDATE_COMMAND:
316                         return; /* Do not touch the submodule. */
317                 }
318         }
319         if (!check_leading_path(ce->name, ce_namelen(ce)))
320                 return;
321         if (remove_or_warn(ce->ce_mode, ce->name))
322                 return;
323         schedule_dir_for_removal(ce->name, ce_namelen(ce));
324 }
325
326 static struct progress *get_progress(struct unpack_trees_options *o)
327 {
328         unsigned cnt = 0, total = 0;
329         struct index_state *index = &o->result;
330
331         if (!o->update || !o->verbose_update)
332                 return NULL;
333
334         for (; cnt < index->cache_nr; cnt++) {
335                 const struct cache_entry *ce = index->cache[cnt];
336                 if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
337                         total++;
338         }
339
340         return start_progress_delay(_("Checking out files"),
341                                     total, 50, 1);
342 }
343
344 static int check_updates(struct unpack_trees_options *o)
345 {
346         unsigned cnt = 0;
347         int errs = 0;
348         struct progress *progress = NULL;
349         struct index_state *index = &o->result;
350         struct checkout state = CHECKOUT_INIT;
351         int i;
352
353         state.force = 1;
354         state.quiet = 1;
355         state.refresh_cache = 1;
356         state.istate = index;
357
358         progress = get_progress(o);
359
360         if (o->update)
361                 git_attr_set_direction(GIT_ATTR_CHECKOUT, index);
362         for (i = 0; i < index->cache_nr; i++) {
363                 const struct cache_entry *ce = index->cache[i];
364
365                 if (ce->ce_flags & CE_WT_REMOVE) {
366                         display_progress(progress, ++cnt);
367                         if (o->update && !o->dry_run)
368                                 unlink_entry(ce);
369                 }
370         }
371         remove_marked_cache_entries(index);
372         remove_scheduled_dirs();
373
374         if (should_update_submodules() && o->update && !o->dry_run)
375                 reload_gitmodules_file(index, &state);
376
377         for (i = 0; i < index->cache_nr; i++) {
378                 struct cache_entry *ce = index->cache[i];
379
380                 if (ce->ce_flags & CE_UPDATE) {
381                         if (ce->ce_flags & CE_WT_REMOVE)
382                                 die("BUG: both update and delete flags are set on %s",
383                                     ce->name);
384                         display_progress(progress, ++cnt);
385                         ce->ce_flags &= ~CE_UPDATE;
386                         if (o->update && !o->dry_run) {
387                                 errs |= checkout_entry(ce, &state, NULL);
388                         }
389                 }
390         }
391         stop_progress(&progress);
392         if (o->update)
393                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
394         return errs != 0;
395 }
396
397 static int verify_uptodate_sparse(const struct cache_entry *ce,
398                                   struct unpack_trees_options *o);
399 static int verify_absent_sparse(const struct cache_entry *ce,
400                                 enum unpack_trees_error_types,
401                                 struct unpack_trees_options *o);
402
403 static int apply_sparse_checkout(struct index_state *istate,
404                                  struct cache_entry *ce,
405                                  struct unpack_trees_options *o)
406 {
407         int was_skip_worktree = ce_skip_worktree(ce);
408
409         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
410                 ce->ce_flags |= CE_SKIP_WORKTREE;
411         else
412                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
413         if (was_skip_worktree != ce_skip_worktree(ce)) {
414                 ce->ce_flags |= CE_UPDATE_IN_BASE;
415                 istate->cache_changed |= CE_ENTRY_CHANGED;
416         }
417
418         /*
419          * if (!was_skip_worktree && !ce_skip_worktree()) {
420          *      This is perfectly normal. Move on;
421          * }
422          */
423
424         /*
425          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
426          * area as a result of ce_skip_worktree() shortcuts in
427          * verify_absent() and verify_uptodate().
428          * Make sure they don't modify worktree if they are already
429          * outside checkout area
430          */
431         if (was_skip_worktree && ce_skip_worktree(ce)) {
432                 ce->ce_flags &= ~CE_UPDATE;
433
434                 /*
435                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
436                  * on to get that file removed from both index and worktree.
437                  * If that file is already outside worktree area, don't
438                  * bother remove it.
439                  */
440                 if (ce->ce_flags & CE_REMOVE)
441                         ce->ce_flags &= ~CE_WT_REMOVE;
442         }
443
444         if (!was_skip_worktree && ce_skip_worktree(ce)) {
445                 /*
446                  * If CE_UPDATE is set, verify_uptodate() must be called already
447                  * also stat info may have lost after merged_entry() so calling
448                  * verify_uptodate() again may fail
449                  */
450                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
451                         return -1;
452                 ce->ce_flags |= CE_WT_REMOVE;
453                 ce->ce_flags &= ~CE_UPDATE;
454         }
455         if (was_skip_worktree && !ce_skip_worktree(ce)) {
456                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
457                         return -1;
458                 ce->ce_flags |= CE_UPDATE;
459         }
460         return 0;
461 }
462
463 static inline int call_unpack_fn(const struct cache_entry * const *src,
464                                  struct unpack_trees_options *o)
465 {
466         int ret = o->fn(src, o);
467         if (ret > 0)
468                 ret = 0;
469         return ret;
470 }
471
472 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
473 {
474         ce->ce_flags |= CE_UNPACKED;
475
476         if (o->cache_bottom < o->src_index->cache_nr &&
477             o->src_index->cache[o->cache_bottom] == ce) {
478                 int bottom = o->cache_bottom;
479                 while (bottom < o->src_index->cache_nr &&
480                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
481                         bottom++;
482                 o->cache_bottom = bottom;
483         }
484 }
485
486 static void mark_all_ce_unused(struct index_state *index)
487 {
488         int i;
489         for (i = 0; i < index->cache_nr; i++)
490                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
491 }
492
493 static int locate_in_src_index(const struct cache_entry *ce,
494                                struct unpack_trees_options *o)
495 {
496         struct index_state *index = o->src_index;
497         int len = ce_namelen(ce);
498         int pos = index_name_pos(index, ce->name, len);
499         if (pos < 0)
500                 pos = -1 - pos;
501         return pos;
502 }
503
504 /*
505  * We call unpack_index_entry() with an unmerged cache entry
506  * only in diff-index, and it wants a single callback.  Skip
507  * the other unmerged entry with the same name.
508  */
509 static void mark_ce_used_same_name(struct cache_entry *ce,
510                                    struct unpack_trees_options *o)
511 {
512         struct index_state *index = o->src_index;
513         int len = ce_namelen(ce);
514         int pos;
515
516         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
517                 struct cache_entry *next = index->cache[pos];
518                 if (len != ce_namelen(next) ||
519                     memcmp(ce->name, next->name, len))
520                         break;
521                 mark_ce_used(next, o);
522         }
523 }
524
525 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
526 {
527         const struct index_state *index = o->src_index;
528         int pos = o->cache_bottom;
529
530         while (pos < index->cache_nr) {
531                 struct cache_entry *ce = index->cache[pos];
532                 if (!(ce->ce_flags & CE_UNPACKED))
533                         return ce;
534                 pos++;
535         }
536         return NULL;
537 }
538
539 static void add_same_unmerged(const struct cache_entry *ce,
540                               struct unpack_trees_options *o)
541 {
542         struct index_state *index = o->src_index;
543         int len = ce_namelen(ce);
544         int pos = index_name_pos(index, ce->name, len);
545
546         if (0 <= pos)
547                 die("programming error in a caller of mark_ce_used_same_name");
548         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
549                 struct cache_entry *next = index->cache[pos];
550                 if (len != ce_namelen(next) ||
551                     memcmp(ce->name, next->name, len))
552                         break;
553                 add_entry(o, next, 0, 0);
554                 mark_ce_used(next, o);
555         }
556 }
557
558 static int unpack_index_entry(struct cache_entry *ce,
559                               struct unpack_trees_options *o)
560 {
561         const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
562         int ret;
563
564         src[0] = ce;
565
566         mark_ce_used(ce, o);
567         if (ce_stage(ce)) {
568                 if (o->skip_unmerged) {
569                         add_entry(o, ce, 0, 0);
570                         return 0;
571                 }
572         }
573         ret = call_unpack_fn(src, o);
574         if (ce_stage(ce))
575                 mark_ce_used_same_name(ce, o);
576         return ret;
577 }
578
579 static int find_cache_pos(struct traverse_info *, const struct name_entry *);
580
581 static void restore_cache_bottom(struct traverse_info *info, int bottom)
582 {
583         struct unpack_trees_options *o = info->data;
584
585         if (o->diff_index_cached)
586                 return;
587         o->cache_bottom = bottom;
588 }
589
590 static int switch_cache_bottom(struct traverse_info *info)
591 {
592         struct unpack_trees_options *o = info->data;
593         int ret, pos;
594
595         if (o->diff_index_cached)
596                 return 0;
597         ret = o->cache_bottom;
598         pos = find_cache_pos(info->prev, &info->name);
599
600         if (pos < -1)
601                 o->cache_bottom = -2 - pos;
602         else if (pos < 0)
603                 o->cache_bottom = o->src_index->cache_nr;
604         return ret;
605 }
606
607 static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
608 {
609         return name_j->oid && name_k->oid && !oidcmp(name_j->oid, name_k->oid);
610 }
611
612 static int traverse_trees_recursive(int n, unsigned long dirmask,
613                                     unsigned long df_conflicts,
614                                     struct name_entry *names,
615                                     struct traverse_info *info)
616 {
617         int i, ret, bottom;
618         int nr_buf = 0;
619         struct tree_desc t[MAX_UNPACK_TREES];
620         void *buf[MAX_UNPACK_TREES];
621         struct traverse_info newinfo;
622         struct name_entry *p;
623
624         p = names;
625         while (!p->mode)
626                 p++;
627
628         newinfo = *info;
629         newinfo.prev = info;
630         newinfo.pathspec = info->pathspec;
631         newinfo.name = *p;
632         newinfo.pathlen += tree_entry_len(p) + 1;
633         newinfo.df_conflicts |= df_conflicts;
634
635         /*
636          * Fetch the tree from the ODB for each peer directory in the
637          * n commits.
638          *
639          * For 2- and 3-way traversals, we try to avoid hitting the
640          * ODB twice for the same OID.  This should yield a nice speed
641          * up in checkouts and merges when the commits are similar.
642          *
643          * We don't bother doing the full O(n^2) search for larger n,
644          * because wider traversals don't happen that often and we
645          * avoid the search setup.
646          *
647          * When 2 peer OIDs are the same, we just copy the tree
648          * descriptor data.  This implicitly borrows the buffer
649          * data from the earlier cell.
650          */
651         for (i = 0; i < n; i++, dirmask >>= 1) {
652                 if (i > 0 && are_same_oid(&names[i], &names[i - 1]))
653                         t[i] = t[i - 1];
654                 else if (i > 1 && are_same_oid(&names[i], &names[i - 2]))
655                         t[i] = t[i - 2];
656                 else {
657                         const unsigned char *sha1 = NULL;
658                         if (dirmask & 1)
659                                 sha1 = names[i].oid->hash;
660                         buf[nr_buf++] = fill_tree_descriptor(t+i, sha1);
661                 }
662         }
663
664         bottom = switch_cache_bottom(&newinfo);
665         ret = traverse_trees(n, t, &newinfo);
666         restore_cache_bottom(&newinfo, bottom);
667
668         for (i = 0; i < nr_buf; i++)
669                 free(buf[i]);
670
671         return ret;
672 }
673
674 /*
675  * Compare the traverse-path to the cache entry without actually
676  * having to generate the textual representation of the traverse
677  * path.
678  *
679  * NOTE! This *only* compares up to the size of the traverse path
680  * itself - the caller needs to do the final check for the cache
681  * entry having more data at the end!
682  */
683 static int do_compare_entry_piecewise(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
684 {
685         int len, pathlen, ce_len;
686         const char *ce_name;
687
688         if (info->prev) {
689                 int cmp = do_compare_entry_piecewise(ce, info->prev,
690                                                      &info->name);
691                 if (cmp)
692                         return cmp;
693         }
694         pathlen = info->pathlen;
695         ce_len = ce_namelen(ce);
696
697         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
698         if (ce_len < pathlen)
699                 return -1;
700
701         ce_len -= pathlen;
702         ce_name = ce->name + pathlen;
703
704         len = tree_entry_len(n);
705         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
706 }
707
708 static int do_compare_entry(const struct cache_entry *ce,
709                             const struct traverse_info *info,
710                             const struct name_entry *n)
711 {
712         int len, pathlen, ce_len;
713         const char *ce_name;
714         int cmp;
715
716         /*
717          * If we have not precomputed the traverse path, it is quicker
718          * to avoid doing so.  But if we have precomputed it,
719          * it is quicker to use the precomputed version.
720          */
721         if (!info->traverse_path)
722                 return do_compare_entry_piecewise(ce, info, n);
723
724         cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
725         if (cmp)
726                 return cmp;
727
728         pathlen = info->pathlen;
729         ce_len = ce_namelen(ce);
730
731         if (ce_len < pathlen)
732                 return -1;
733
734         ce_len -= pathlen;
735         ce_name = ce->name + pathlen;
736
737         len = tree_entry_len(n);
738         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
739 }
740
741 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
742 {
743         int cmp = do_compare_entry(ce, info, n);
744         if (cmp)
745                 return cmp;
746
747         /*
748          * Even if the beginning compared identically, the ce should
749          * compare as bigger than a directory leading up to it!
750          */
751         return ce_namelen(ce) > traverse_path_len(info, n);
752 }
753
754 static int ce_in_traverse_path(const struct cache_entry *ce,
755                                const struct traverse_info *info)
756 {
757         if (!info->prev)
758                 return 1;
759         if (do_compare_entry(ce, info->prev, &info->name))
760                 return 0;
761         /*
762          * If ce (blob) is the same name as the path (which is a tree
763          * we will be descending into), it won't be inside it.
764          */
765         return (info->pathlen < ce_namelen(ce));
766 }
767
768 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
769 {
770         int len = traverse_path_len(info, n);
771         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
772
773         ce->ce_mode = create_ce_mode(n->mode);
774         ce->ce_flags = create_ce_flags(stage);
775         ce->ce_namelen = len;
776         oidcpy(&ce->oid, n->oid);
777         make_traverse_path(ce->name, info, n);
778
779         return ce;
780 }
781
782 static int unpack_nondirectories(int n, unsigned long mask,
783                                  unsigned long dirmask,
784                                  struct cache_entry **src,
785                                  const struct name_entry *names,
786                                  const struct traverse_info *info)
787 {
788         int i;
789         struct unpack_trees_options *o = info->data;
790         unsigned long conflicts = info->df_conflicts | dirmask;
791
792         /* Do we have *only* directories? Nothing to do */
793         if (mask == dirmask && !src[0])
794                 return 0;
795
796         /*
797          * Ok, we've filled in up to any potential index entry in src[0],
798          * now do the rest.
799          */
800         for (i = 0; i < n; i++) {
801                 int stage;
802                 unsigned int bit = 1ul << i;
803                 if (conflicts & bit) {
804                         src[i + o->merge] = o->df_conflict_entry;
805                         continue;
806                 }
807                 if (!(mask & bit))
808                         continue;
809                 if (!o->merge)
810                         stage = 0;
811                 else if (i + 1 < o->head_idx)
812                         stage = 1;
813                 else if (i + 1 > o->head_idx)
814                         stage = 3;
815                 else
816                         stage = 2;
817                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
818         }
819
820         if (o->merge) {
821                 int rc = call_unpack_fn((const struct cache_entry * const *)src,
822                                         o);
823                 for (i = 0; i < n; i++) {
824                         struct cache_entry *ce = src[i + o->merge];
825                         if (ce != o->df_conflict_entry)
826                                 free(ce);
827                 }
828                 return rc;
829         }
830
831         for (i = 0; i < n; i++)
832                 if (src[i] && src[i] != o->df_conflict_entry)
833                         if (do_add_entry(o, src[i], 0, 0))
834                                 return -1;
835
836         return 0;
837 }
838
839 static int unpack_failed(struct unpack_trees_options *o, const char *message)
840 {
841         discard_index(&o->result);
842         if (!o->gently && !o->exiting_early) {
843                 if (message)
844                         return error("%s", message);
845                 return -1;
846         }
847         return -1;
848 }
849
850 /*
851  * The tree traversal is looking at name p.  If we have a matching entry,
852  * return it.  If name p is a directory in the index, do not return
853  * anything, as we will want to match it when the traversal descends into
854  * the directory.
855  */
856 static int find_cache_pos(struct traverse_info *info,
857                           const struct name_entry *p)
858 {
859         int pos;
860         struct unpack_trees_options *o = info->data;
861         struct index_state *index = o->src_index;
862         int pfxlen = info->pathlen;
863         int p_len = tree_entry_len(p);
864
865         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
866                 const struct cache_entry *ce = index->cache[pos];
867                 const char *ce_name, *ce_slash;
868                 int cmp, ce_len;
869
870                 if (ce->ce_flags & CE_UNPACKED) {
871                         /*
872                          * cache_bottom entry is already unpacked, so
873                          * we can never match it; don't check it
874                          * again.
875                          */
876                         if (pos == o->cache_bottom)
877                                 ++o->cache_bottom;
878                         continue;
879                 }
880                 if (!ce_in_traverse_path(ce, info)) {
881                         /*
882                          * Check if we can skip future cache checks
883                          * (because we're already past all possible
884                          * entries in the traverse path).
885                          */
886                         if (info->traverse_path) {
887                                 if (strncmp(ce->name, info->traverse_path,
888                                             info->pathlen) > 0)
889                                         break;
890                         }
891                         continue;
892                 }
893                 ce_name = ce->name + pfxlen;
894                 ce_slash = strchr(ce_name, '/');
895                 if (ce_slash)
896                         ce_len = ce_slash - ce_name;
897                 else
898                         ce_len = ce_namelen(ce) - pfxlen;
899                 cmp = name_compare(p->path, p_len, ce_name, ce_len);
900                 /*
901                  * Exact match; if we have a directory we need to
902                  * delay returning it.
903                  */
904                 if (!cmp)
905                         return ce_slash ? -2 - pos : pos;
906                 if (0 < cmp)
907                         continue; /* keep looking */
908                 /*
909                  * ce_name sorts after p->path; could it be that we
910                  * have files under p->path directory in the index?
911                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
912                  * have "t/a" in the index.
913                  */
914                 if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
915                     ce_name[p_len] < '/')
916                         continue; /* keep looking */
917                 break;
918         }
919         return -1;
920 }
921
922 static struct cache_entry *find_cache_entry(struct traverse_info *info,
923                                             const struct name_entry *p)
924 {
925         int pos = find_cache_pos(info, p);
926         struct unpack_trees_options *o = info->data;
927
928         if (0 <= pos)
929                 return o->src_index->cache[pos];
930         else
931                 return NULL;
932 }
933
934 static void debug_path(struct traverse_info *info)
935 {
936         if (info->prev) {
937                 debug_path(info->prev);
938                 if (*info->prev->name.path)
939                         putchar('/');
940         }
941         printf("%s", info->name.path);
942 }
943
944 static void debug_name_entry(int i, struct name_entry *n)
945 {
946         printf("ent#%d %06o %s\n", i,
947                n->path ? n->mode : 0,
948                n->path ? n->path : "(missing)");
949 }
950
951 static void debug_unpack_callback(int n,
952                                   unsigned long mask,
953                                   unsigned long dirmask,
954                                   struct name_entry *names,
955                                   struct traverse_info *info)
956 {
957         int i;
958         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
959                mask, dirmask, n);
960         debug_path(info);
961         putchar('\n');
962         for (i = 0; i < n; i++)
963                 debug_name_entry(i, names + i);
964 }
965
966 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
967 {
968         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
969         struct unpack_trees_options *o = info->data;
970         const struct name_entry *p = names;
971
972         /* Find first entry with a real name (we could use "mask" too) */
973         while (!p->mode)
974                 p++;
975
976         if (o->debug_unpack)
977                 debug_unpack_callback(n, mask, dirmask, names, info);
978
979         /* Are we supposed to look at the index too? */
980         if (o->merge) {
981                 while (1) {
982                         int cmp;
983                         struct cache_entry *ce;
984
985                         if (o->diff_index_cached)
986                                 ce = next_cache_entry(o);
987                         else
988                                 ce = find_cache_entry(info, p);
989
990                         if (!ce)
991                                 break;
992                         cmp = compare_entry(ce, info, p);
993                         if (cmp < 0) {
994                                 if (unpack_index_entry(ce, o) < 0)
995                                         return unpack_failed(o, NULL);
996                                 continue;
997                         }
998                         if (!cmp) {
999                                 if (ce_stage(ce)) {
1000                                         /*
1001                                          * If we skip unmerged index
1002                                          * entries, we'll skip this
1003                                          * entry *and* the tree
1004                                          * entries associated with it!
1005                                          */
1006                                         if (o->skip_unmerged) {
1007                                                 add_same_unmerged(ce, o);
1008                                                 return mask;
1009                                         }
1010                                 }
1011                                 src[0] = ce;
1012                         }
1013                         break;
1014                 }
1015         }
1016
1017         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
1018                 return -1;
1019
1020         if (o->merge && src[0]) {
1021                 if (ce_stage(src[0]))
1022                         mark_ce_used_same_name(src[0], o);
1023                 else
1024                         mark_ce_used(src[0], o);
1025         }
1026
1027         /* Now handle any directories.. */
1028         if (dirmask) {
1029                 /* special case: "diff-index --cached" looking at a tree */
1030                 if (o->diff_index_cached &&
1031                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
1032                         int matches;
1033                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
1034                                                                names, info);
1035                         /*
1036                          * Everything under the name matches; skip the
1037                          * entire hierarchy.  diff_index_cached codepath
1038                          * special cases D/F conflicts in such a way that
1039                          * it does not do any look-ahead, so this is safe.
1040                          */
1041                         if (matches) {
1042                                 o->cache_bottom += matches;
1043                                 return mask;
1044                         }
1045                 }
1046
1047                 if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
1048                                              names, info) < 0)
1049                         return -1;
1050                 return mask;
1051         }
1052
1053         return mask;
1054 }
1055
1056 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
1057                             struct strbuf *prefix,
1058                             int select_mask, int clear_mask,
1059                             struct exclude_list *el, int defval);
1060
1061 /* Whole directory matching */
1062 static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
1063                               struct strbuf *prefix,
1064                               char *basename,
1065                               int select_mask, int clear_mask,
1066                               struct exclude_list *el, int defval)
1067 {
1068         struct cache_entry **cache_end;
1069         int dtype = DT_DIR;
1070         int ret = is_excluded_from_list(prefix->buf, prefix->len,
1071                                         basename, &dtype, el);
1072         int rc;
1073
1074         strbuf_addch(prefix, '/');
1075
1076         /* If undecided, use matching result of parent dir in defval */
1077         if (ret < 0)
1078                 ret = defval;
1079
1080         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
1081                 struct cache_entry *ce = *cache_end;
1082                 if (strncmp(ce->name, prefix->buf, prefix->len))
1083                         break;
1084         }
1085
1086         /*
1087          * TODO: check el, if there are no patterns that may conflict
1088          * with ret (iow, we know in advance the incl/excl
1089          * decision for the entire directory), clear flag here without
1090          * calling clear_ce_flags_1(). That function will call
1091          * the expensive is_excluded_from_list() on every entry.
1092          */
1093         rc = clear_ce_flags_1(cache, cache_end - cache,
1094                               prefix,
1095                               select_mask, clear_mask,
1096                               el, ret);
1097         strbuf_setlen(prefix, prefix->len - 1);
1098         return rc;
1099 }
1100
1101 /*
1102  * Traverse the index, find every entry that matches according to
1103  * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
1104  * number of traversed entries.
1105  *
1106  * If select_mask is non-zero, only entries whose ce_flags has on of
1107  * those bits enabled are traversed.
1108  *
1109  * cache        : pointer to an index entry
1110  * prefix_len   : an offset to its path
1111  *
1112  * The current path ("prefix") including the trailing '/' is
1113  *   cache[0]->name[0..(prefix_len-1)]
1114  * Top level path has prefix_len zero.
1115  */
1116 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
1117                             struct strbuf *prefix,
1118                             int select_mask, int clear_mask,
1119                             struct exclude_list *el, int defval)
1120 {
1121         struct cache_entry **cache_end = cache + nr;
1122
1123         /*
1124          * Process all entries that have the given prefix and meet
1125          * select_mask condition
1126          */
1127         while(cache != cache_end) {
1128                 struct cache_entry *ce = *cache;
1129                 const char *name, *slash;
1130                 int len, dtype, ret;
1131
1132                 if (select_mask && !(ce->ce_flags & select_mask)) {
1133                         cache++;
1134                         continue;
1135                 }
1136
1137                 if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
1138                         break;
1139
1140                 name = ce->name + prefix->len;
1141                 slash = strchr(name, '/');
1142
1143                 /* If it's a directory, try whole directory match first */
1144                 if (slash) {
1145                         int processed;
1146
1147                         len = slash - name;
1148                         strbuf_add(prefix, name, len);
1149
1150                         processed = clear_ce_flags_dir(cache, cache_end - cache,
1151                                                        prefix,
1152                                                        prefix->buf + prefix->len - len,
1153                                                        select_mask, clear_mask,
1154                                                        el, defval);
1155
1156                         /* clear_c_f_dir eats a whole dir already? */
1157                         if (processed) {
1158                                 cache += processed;
1159                                 strbuf_setlen(prefix, prefix->len - len);
1160                                 continue;
1161                         }
1162
1163                         strbuf_addch(prefix, '/');
1164                         cache += clear_ce_flags_1(cache, cache_end - cache,
1165                                                   prefix,
1166                                                   select_mask, clear_mask, el, defval);
1167                         strbuf_setlen(prefix, prefix->len - len - 1);
1168                         continue;
1169                 }
1170
1171                 /* Non-directory */
1172                 dtype = ce_to_dtype(ce);
1173                 ret = is_excluded_from_list(ce->name, ce_namelen(ce),
1174                                             name, &dtype, el);
1175                 if (ret < 0)
1176                         ret = defval;
1177                 if (ret > 0)
1178                         ce->ce_flags &= ~clear_mask;
1179                 cache++;
1180         }
1181         return nr - (cache_end - cache);
1182 }
1183
1184 static int clear_ce_flags(struct cache_entry **cache, int nr,
1185                             int select_mask, int clear_mask,
1186                             struct exclude_list *el)
1187 {
1188         static struct strbuf prefix = STRBUF_INIT;
1189
1190         strbuf_reset(&prefix);
1191
1192         return clear_ce_flags_1(cache, nr,
1193                                 &prefix,
1194                                 select_mask, clear_mask,
1195                                 el, 0);
1196 }
1197
1198 /*
1199  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1200  */
1201 static void mark_new_skip_worktree(struct exclude_list *el,
1202                                    struct index_state *the_index,
1203                                    int select_flag, int skip_wt_flag)
1204 {
1205         int i;
1206
1207         /*
1208          * 1. Pretend the narrowest worktree: only unmerged entries
1209          * are checked out
1210          */
1211         for (i = 0; i < the_index->cache_nr; i++) {
1212                 struct cache_entry *ce = the_index->cache[i];
1213
1214                 if (select_flag && !(ce->ce_flags & select_flag))
1215                         continue;
1216
1217                 if (!ce_stage(ce))
1218                         ce->ce_flags |= skip_wt_flag;
1219                 else
1220                         ce->ce_flags &= ~skip_wt_flag;
1221         }
1222
1223         /*
1224          * 2. Widen worktree according to sparse-checkout file.
1225          * Matched entries will have skip_wt_flag cleared (i.e. "in")
1226          */
1227         clear_ce_flags(the_index->cache, the_index->cache_nr,
1228                        select_flag, skip_wt_flag, el);
1229 }
1230
1231 static int verify_absent(const struct cache_entry *,
1232                          enum unpack_trees_error_types,
1233                          struct unpack_trees_options *);
1234 /*
1235  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1236  * resulting index, -2 on failure to reflect the changes to the work tree.
1237  *
1238  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1239  */
1240 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1241 {
1242         int i, ret;
1243         static struct cache_entry *dfc;
1244         struct exclude_list el;
1245
1246         if (len > MAX_UNPACK_TREES)
1247                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1248
1249         memset(&el, 0, sizeof(el));
1250         if (!core_apply_sparse_checkout || !o->update)
1251                 o->skip_sparse_checkout = 1;
1252         if (!o->skip_sparse_checkout) {
1253                 char *sparse = git_pathdup("info/sparse-checkout");
1254                 if (add_excludes_from_file_to_list(sparse, "", 0, &el, 0) < 0)
1255                         o->skip_sparse_checkout = 1;
1256                 else
1257                         o->el = &el;
1258                 free(sparse);
1259         }
1260
1261         memset(&o->result, 0, sizeof(o->result));
1262         o->result.initialized = 1;
1263         o->result.timestamp.sec = o->src_index->timestamp.sec;
1264         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1265         o->result.version = o->src_index->version;
1266         o->result.split_index = o->src_index->split_index;
1267         if (o->result.split_index)
1268                 o->result.split_index->refcount++;
1269         hashcpy(o->result.sha1, o->src_index->sha1);
1270         o->merge_size = len;
1271         mark_all_ce_unused(o->src_index);
1272
1273         /*
1274          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1275          */
1276         if (!o->skip_sparse_checkout)
1277                 mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1278
1279         if (!dfc)
1280                 dfc = xcalloc(1, cache_entry_size(0));
1281         o->df_conflict_entry = dfc;
1282
1283         if (len) {
1284                 const char *prefix = o->prefix ? o->prefix : "";
1285                 struct traverse_info info;
1286
1287                 setup_traverse_info(&info, prefix);
1288                 info.fn = unpack_callback;
1289                 info.data = o;
1290                 info.show_all_errors = o->show_all_errors;
1291                 info.pathspec = o->pathspec;
1292
1293                 if (o->prefix) {
1294                         /*
1295                          * Unpack existing index entries that sort before the
1296                          * prefix the tree is spliced into.  Note that o->merge
1297                          * is always true in this case.
1298                          */
1299                         while (1) {
1300                                 struct cache_entry *ce = next_cache_entry(o);
1301                                 if (!ce)
1302                                         break;
1303                                 if (ce_in_traverse_path(ce, &info))
1304                                         break;
1305                                 if (unpack_index_entry(ce, o) < 0)
1306                                         goto return_failed;
1307                         }
1308                 }
1309
1310                 if (traverse_trees(len, t, &info) < 0)
1311                         goto return_failed;
1312         }
1313
1314         /* Any left-over entries in the index? */
1315         if (o->merge) {
1316                 while (1) {
1317                         struct cache_entry *ce = next_cache_entry(o);
1318                         if (!ce)
1319                                 break;
1320                         if (unpack_index_entry(ce, o) < 0)
1321                                 goto return_failed;
1322                 }
1323         }
1324         mark_all_ce_unused(o->src_index);
1325
1326         if (o->trivial_merges_only && o->nontrivial_merge) {
1327                 ret = unpack_failed(o, "Merge requires file-level merging");
1328                 goto done;
1329         }
1330
1331         if (!o->skip_sparse_checkout) {
1332                 int empty_worktree = 1;
1333
1334                 /*
1335                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1336                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1337                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1338                  */
1339                 mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1340
1341                 ret = 0;
1342                 for (i = 0; i < o->result.cache_nr; i++) {
1343                         struct cache_entry *ce = o->result.cache[i];
1344
1345                         /*
1346                          * Entries marked with CE_ADDED in merged_entry() do not have
1347                          * verify_absent() check (the check is effectively disabled
1348                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1349                          *
1350                          * Do the real check now because we have had
1351                          * correct CE_NEW_SKIP_WORKTREE
1352                          */
1353                         if (ce->ce_flags & CE_ADDED &&
1354                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1355                                 if (!o->show_all_errors)
1356                                         goto return_failed;
1357                                 ret = -1;
1358                         }
1359
1360                         if (apply_sparse_checkout(&o->result, ce, o)) {
1361                                 if (!o->show_all_errors)
1362                                         goto return_failed;
1363                                 ret = -1;
1364                         }
1365                         if (!ce_skip_worktree(ce))
1366                                 empty_worktree = 0;
1367
1368                 }
1369                 if (ret < 0)
1370                         goto return_failed;
1371                 /*
1372                  * Sparse checkout is meant to narrow down checkout area
1373                  * but it does not make sense to narrow down to empty working
1374                  * tree. This is usually a mistake in sparse checkout rules.
1375                  * Do not allow users to do that.
1376                  */
1377                 if (o->result.cache_nr && empty_worktree) {
1378                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1379                         goto done;
1380                 }
1381         }
1382
1383         o->src_index = NULL;
1384         ret = check_updates(o) ? (-2) : 0;
1385         if (o->dst_index) {
1386                 if (!ret) {
1387                         if (!o->result.cache_tree)
1388                                 o->result.cache_tree = cache_tree();
1389                         if (!cache_tree_fully_valid(o->result.cache_tree))
1390                                 cache_tree_update(&o->result,
1391                                                   WRITE_TREE_SILENT |
1392                                                   WRITE_TREE_REPAIR);
1393                 }
1394                 discard_index(o->dst_index);
1395                 *o->dst_index = o->result;
1396         } else {
1397                 discard_index(&o->result);
1398         }
1399
1400 done:
1401         clear_exclude_list(&el);
1402         return ret;
1403
1404 return_failed:
1405         if (o->show_all_errors)
1406                 display_error_msgs(o);
1407         mark_all_ce_unused(o->src_index);
1408         ret = unpack_failed(o, NULL);
1409         if (o->exiting_early)
1410                 ret = 0;
1411         goto done;
1412 }
1413
1414 /* Here come the merge functions */
1415
1416 static int reject_merge(const struct cache_entry *ce,
1417                         struct unpack_trees_options *o)
1418 {
1419         return o->gently ? -1 :
1420                 add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1421 }
1422
1423 static int same(const struct cache_entry *a, const struct cache_entry *b)
1424 {
1425         if (!!a != !!b)
1426                 return 0;
1427         if (!a && !b)
1428                 return 1;
1429         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1430                 return 0;
1431         return a->ce_mode == b->ce_mode &&
1432                !oidcmp(&a->oid, &b->oid);
1433 }
1434
1435
1436 /*
1437  * When a CE gets turned into an unmerged entry, we
1438  * want it to be up-to-date
1439  */
1440 static int verify_uptodate_1(const struct cache_entry *ce,
1441                              struct unpack_trees_options *o,
1442                              enum unpack_trees_error_types error_type)
1443 {
1444         struct stat st;
1445
1446         if (o->index_only)
1447                 return 0;
1448
1449         /*
1450          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1451          * if this entry is truly up-to-date because this file may be
1452          * overwritten.
1453          */
1454         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1455                 ; /* keep checking */
1456         else if (o->reset || ce_uptodate(ce))
1457                 return 0;
1458
1459         if (!lstat(ce->name, &st)) {
1460                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1461                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1462
1463                 if (submodule_from_ce(ce)) {
1464                         int r = check_submodule_move_head(ce,
1465                                 "HEAD", oid_to_hex(&ce->oid), o);
1466                         if (r)
1467                                 return o->gently ? -1 :
1468                                         add_rejected_path(o, error_type, ce->name);
1469                         return 0;
1470                 }
1471
1472                 if (!changed)
1473                         return 0;
1474                 /*
1475                  * Historic default policy was to allow submodule to be out
1476                  * of sync wrt the superproject index. If the submodule was
1477                  * not considered interesting above, we don't care here.
1478                  */
1479                 if (S_ISGITLINK(ce->ce_mode))
1480                         return 0;
1481
1482                 errno = 0;
1483         }
1484         if (errno == ENOENT)
1485                 return 0;
1486         return o->gently ? -1 :
1487                 add_rejected_path(o, error_type, ce->name);
1488 }
1489
1490 static int verify_uptodate(const struct cache_entry *ce,
1491                            struct unpack_trees_options *o)
1492 {
1493         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1494                 return 0;
1495         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1496 }
1497
1498 static int verify_uptodate_sparse(const struct cache_entry *ce,
1499                                   struct unpack_trees_options *o)
1500 {
1501         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1502 }
1503
1504 static void invalidate_ce_path(const struct cache_entry *ce,
1505                                struct unpack_trees_options *o)
1506 {
1507         if (!ce)
1508                 return;
1509         cache_tree_invalidate_path(o->src_index, ce->name);
1510         untracked_cache_invalidate_path(o->src_index, ce->name);
1511 }
1512
1513 /*
1514  * Check that checking out ce->sha1 in subdir ce->name is not
1515  * going to overwrite any working files.
1516  *
1517  * Currently, git does not checkout subprojects during a superproject
1518  * checkout, so it is not going to overwrite anything.
1519  */
1520 static int verify_clean_submodule(const char *old_sha1,
1521                                   const struct cache_entry *ce,
1522                                   enum unpack_trees_error_types error_type,
1523                                   struct unpack_trees_options *o)
1524 {
1525         if (!submodule_from_ce(ce))
1526                 return 0;
1527
1528         return check_submodule_move_head(ce, old_sha1,
1529                                          oid_to_hex(&ce->oid), o);
1530 }
1531
1532 static int verify_clean_subdirectory(const struct cache_entry *ce,
1533                                      enum unpack_trees_error_types error_type,
1534                                      struct unpack_trees_options *o)
1535 {
1536         /*
1537          * we are about to extract "ce->name"; we would not want to lose
1538          * anything in the existing directory there.
1539          */
1540         int namelen;
1541         int i;
1542         struct dir_struct d;
1543         char *pathbuf;
1544         int cnt = 0;
1545
1546         if (S_ISGITLINK(ce->ce_mode)) {
1547                 unsigned char sha1[20];
1548                 int sub_head = resolve_gitlink_ref(ce->name, "HEAD", sha1);
1549                 /*
1550                  * If we are not going to update the submodule, then
1551                  * we don't care.
1552                  */
1553                 if (!sub_head && !hashcmp(sha1, ce->oid.hash))
1554                         return 0;
1555                 return verify_clean_submodule(sub_head ? NULL : sha1_to_hex(sha1),
1556                                               ce, error_type, o);
1557         }
1558
1559         /*
1560          * First let's make sure we do not have a local modification
1561          * in that directory.
1562          */
1563         namelen = ce_namelen(ce);
1564         for (i = locate_in_src_index(ce, o);
1565              i < o->src_index->cache_nr;
1566              i++) {
1567                 struct cache_entry *ce2 = o->src_index->cache[i];
1568                 int len = ce_namelen(ce2);
1569                 if (len < namelen ||
1570                     strncmp(ce->name, ce2->name, namelen) ||
1571                     ce2->name[namelen] != '/')
1572                         break;
1573                 /*
1574                  * ce2->name is an entry in the subdirectory to be
1575                  * removed.
1576                  */
1577                 if (!ce_stage(ce2)) {
1578                         if (verify_uptodate(ce2, o))
1579                                 return -1;
1580                         add_entry(o, ce2, CE_REMOVE, 0);
1581                         mark_ce_used(ce2, o);
1582                 }
1583                 cnt++;
1584         }
1585
1586         /*
1587          * Then we need to make sure that we do not lose a locally
1588          * present file that is not ignored.
1589          */
1590         pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1591
1592         memset(&d, 0, sizeof(d));
1593         if (o->dir)
1594                 d.exclude_per_dir = o->dir->exclude_per_dir;
1595         i = read_directory(&d, pathbuf, namelen+1, NULL);
1596         if (i)
1597                 return o->gently ? -1 :
1598                         add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1599         free(pathbuf);
1600         return cnt;
1601 }
1602
1603 /*
1604  * This gets called when there was no index entry for the tree entry 'dst',
1605  * but we found a file in the working tree that 'lstat()' said was fine,
1606  * and we're on a case-insensitive filesystem.
1607  *
1608  * See if we can find a case-insensitive match in the index that also
1609  * matches the stat information, and assume it's that other file!
1610  */
1611 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1612 {
1613         const struct cache_entry *src;
1614
1615         src = index_file_exists(o->src_index, name, len, 1);
1616         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1617 }
1618
1619 static int check_ok_to_remove(const char *name, int len, int dtype,
1620                               const struct cache_entry *ce, struct stat *st,
1621                               enum unpack_trees_error_types error_type,
1622                               struct unpack_trees_options *o)
1623 {
1624         const struct cache_entry *result;
1625
1626         /*
1627          * It may be that the 'lstat()' succeeded even though
1628          * target 'ce' was absent, because there is an old
1629          * entry that is different only in case..
1630          *
1631          * Ignore that lstat() if it matches.
1632          */
1633         if (ignore_case && icase_exists(o, name, len, st))
1634                 return 0;
1635
1636         if (o->dir &&
1637             is_excluded(o->dir, name, &dtype))
1638                 /*
1639                  * ce->name is explicitly excluded, so it is Ok to
1640                  * overwrite it.
1641                  */
1642                 return 0;
1643         if (S_ISDIR(st->st_mode)) {
1644                 /*
1645                  * We are checking out path "foo" and
1646                  * found "foo/." in the working tree.
1647                  * This is tricky -- if we have modified
1648                  * files that are in "foo/" we would lose
1649                  * them.
1650                  */
1651                 if (verify_clean_subdirectory(ce, error_type, o) < 0)
1652                         return -1;
1653                 return 0;
1654         }
1655
1656         /*
1657          * The previous round may already have decided to
1658          * delete this path, which is in a subdirectory that
1659          * is being replaced with a blob.
1660          */
1661         result = index_file_exists(&o->result, name, len, 0);
1662         if (result) {
1663                 if (result->ce_flags & CE_REMOVE)
1664                         return 0;
1665         }
1666
1667         return o->gently ? -1 :
1668                 add_rejected_path(o, error_type, name);
1669 }
1670
1671 /*
1672  * We do not want to remove or overwrite a working tree file that
1673  * is not tracked, unless it is ignored.
1674  */
1675 static int verify_absent_1(const struct cache_entry *ce,
1676                            enum unpack_trees_error_types error_type,
1677                            struct unpack_trees_options *o)
1678 {
1679         int len;
1680         struct stat st;
1681
1682         if (o->index_only || o->reset || !o->update)
1683                 return 0;
1684
1685         len = check_leading_path(ce->name, ce_namelen(ce));
1686         if (!len)
1687                 return 0;
1688         else if (len > 0) {
1689                 char *path;
1690                 int ret;
1691
1692                 path = xmemdupz(ce->name, len);
1693                 if (lstat(path, &st))
1694                         ret = error_errno("cannot stat '%s'", path);
1695                 else {
1696                         if (submodule_from_ce(ce))
1697                                 ret = check_submodule_move_head(ce,
1698                                                                 oid_to_hex(&ce->oid),
1699                                                                 NULL, o);
1700                         else
1701                                 ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
1702                                                          &st, error_type, o);
1703                 }
1704                 free(path);
1705                 return ret;
1706         } else if (lstat(ce->name, &st)) {
1707                 if (errno != ENOENT)
1708                         return error_errno("cannot stat '%s'", ce->name);
1709                 return 0;
1710         } else {
1711                 if (submodule_from_ce(ce))
1712                         return check_submodule_move_head(ce, oid_to_hex(&ce->oid),
1713                                                          NULL, o);
1714
1715                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1716                                           ce_to_dtype(ce), ce, &st,
1717                                           error_type, o);
1718         }
1719 }
1720
1721 static int verify_absent(const struct cache_entry *ce,
1722                          enum unpack_trees_error_types error_type,
1723                          struct unpack_trees_options *o)
1724 {
1725         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1726                 return 0;
1727         return verify_absent_1(ce, error_type, o);
1728 }
1729
1730 static int verify_absent_sparse(const struct cache_entry *ce,
1731                                 enum unpack_trees_error_types error_type,
1732                                 struct unpack_trees_options *o)
1733 {
1734         enum unpack_trees_error_types orphaned_error = error_type;
1735         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1736                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1737
1738         return verify_absent_1(ce, orphaned_error, o);
1739 }
1740
1741 static int merged_entry(const struct cache_entry *ce,
1742                         const struct cache_entry *old,
1743                         struct unpack_trees_options *o)
1744 {
1745         int update = CE_UPDATE;
1746         struct cache_entry *merge = dup_entry(ce);
1747
1748         if (!old) {
1749                 /*
1750                  * New index entries. In sparse checkout, the following
1751                  * verify_absent() will be delayed until after
1752                  * traverse_trees() finishes in unpack_trees(), then:
1753                  *
1754                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1755                  *  - verify_absent() be called again, this time with
1756                  *    correct CE_NEW_SKIP_WORKTREE
1757                  *
1758                  * verify_absent() call here does nothing in sparse
1759                  * checkout (i.e. o->skip_sparse_checkout == 0)
1760                  */
1761                 update |= CE_ADDED;
1762                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1763
1764                 if (verify_absent(merge,
1765                                   ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1766                         free(merge);
1767                         return -1;
1768                 }
1769                 invalidate_ce_path(merge, o);
1770
1771                 if (submodule_from_ce(ce)) {
1772                         int ret = check_submodule_move_head(ce, NULL,
1773                                                             oid_to_hex(&ce->oid),
1774                                                             o);
1775                         if (ret)
1776                                 return ret;
1777                 }
1778
1779         } else if (!(old->ce_flags & CE_CONFLICTED)) {
1780                 /*
1781                  * See if we can re-use the old CE directly?
1782                  * That way we get the uptodate stat info.
1783                  *
1784                  * This also removes the UPDATE flag on a match; otherwise
1785                  * we will end up overwriting local changes in the work tree.
1786                  */
1787                 if (same(old, merge)) {
1788                         copy_cache_entry(merge, old);
1789                         update = 0;
1790                 } else {
1791                         if (verify_uptodate(old, o)) {
1792                                 free(merge);
1793                                 return -1;
1794                         }
1795                         /* Migrate old flags over */
1796                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1797                         invalidate_ce_path(old, o);
1798                 }
1799
1800                 if (submodule_from_ce(ce)) {
1801                         int ret = check_submodule_move_head(ce, oid_to_hex(&old->oid),
1802                                                             oid_to_hex(&ce->oid),
1803                                                             o);
1804                         if (ret)
1805                                 return ret;
1806                 }
1807         } else {
1808                 /*
1809                  * Previously unmerged entry left as an existence
1810                  * marker by read_index_unmerged();
1811                  */
1812                 invalidate_ce_path(old, o);
1813         }
1814
1815         do_add_entry(o, merge, update, CE_STAGEMASK);
1816         return 1;
1817 }
1818
1819 static int deleted_entry(const struct cache_entry *ce,
1820                          const struct cache_entry *old,
1821                          struct unpack_trees_options *o)
1822 {
1823         /* Did it exist in the index? */
1824         if (!old) {
1825                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1826                         return -1;
1827                 return 0;
1828         }
1829         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1830                 return -1;
1831         add_entry(o, ce, CE_REMOVE, 0);
1832         invalidate_ce_path(ce, o);
1833         return 1;
1834 }
1835
1836 static int keep_entry(const struct cache_entry *ce,
1837                       struct unpack_trees_options *o)
1838 {
1839         add_entry(o, ce, 0, 0);
1840         return 1;
1841 }
1842
1843 #if DBRT_DEBUG
1844 static void show_stage_entry(FILE *o,
1845                              const char *label, const struct cache_entry *ce)
1846 {
1847         if (!ce)
1848                 fprintf(o, "%s (missing)\n", label);
1849         else
1850                 fprintf(o, "%s%06o %s %d\t%s\n",
1851                         label,
1852                         ce->ce_mode,
1853                         oid_to_hex(&ce->oid),
1854                         ce_stage(ce),
1855                         ce->name);
1856 }
1857 #endif
1858
1859 int threeway_merge(const struct cache_entry * const *stages,
1860                    struct unpack_trees_options *o)
1861 {
1862         const struct cache_entry *index;
1863         const struct cache_entry *head;
1864         const struct cache_entry *remote = stages[o->head_idx + 1];
1865         int count;
1866         int head_match = 0;
1867         int remote_match = 0;
1868
1869         int df_conflict_head = 0;
1870         int df_conflict_remote = 0;
1871
1872         int any_anc_missing = 0;
1873         int no_anc_exists = 1;
1874         int i;
1875
1876         for (i = 1; i < o->head_idx; i++) {
1877                 if (!stages[i] || stages[i] == o->df_conflict_entry)
1878                         any_anc_missing = 1;
1879                 else
1880                         no_anc_exists = 0;
1881         }
1882
1883         index = stages[0];
1884         head = stages[o->head_idx];
1885
1886         if (head == o->df_conflict_entry) {
1887                 df_conflict_head = 1;
1888                 head = NULL;
1889         }
1890
1891         if (remote == o->df_conflict_entry) {
1892                 df_conflict_remote = 1;
1893                 remote = NULL;
1894         }
1895
1896         /*
1897          * First, if there's a #16 situation, note that to prevent #13
1898          * and #14.
1899          */
1900         if (!same(remote, head)) {
1901                 for (i = 1; i < o->head_idx; i++) {
1902                         if (same(stages[i], head)) {
1903                                 head_match = i;
1904                         }
1905                         if (same(stages[i], remote)) {
1906                                 remote_match = i;
1907                         }
1908                 }
1909         }
1910
1911         /*
1912          * We start with cases where the index is allowed to match
1913          * something other than the head: #14(ALT) and #2ALT, where it
1914          * is permitted to match the result instead.
1915          */
1916         /* #14, #14ALT, #2ALT */
1917         if (remote && !df_conflict_head && head_match && !remote_match) {
1918                 if (index && !same(index, remote) && !same(index, head))
1919                         return reject_merge(index, o);
1920                 return merged_entry(remote, index, o);
1921         }
1922         /*
1923          * If we have an entry in the index cache, then we want to
1924          * make sure that it matches head.
1925          */
1926         if (index && !same(index, head))
1927                 return reject_merge(index, o);
1928
1929         if (head) {
1930                 /* #5ALT, #15 */
1931                 if (same(head, remote))
1932                         return merged_entry(head, index, o);
1933                 /* #13, #3ALT */
1934                 if (!df_conflict_remote && remote_match && !head_match)
1935                         return merged_entry(head, index, o);
1936         }
1937
1938         /* #1 */
1939         if (!head && !remote && any_anc_missing)
1940                 return 0;
1941
1942         /*
1943          * Under the "aggressive" rule, we resolve mostly trivial
1944          * cases that we historically had git-merge-one-file resolve.
1945          */
1946         if (o->aggressive) {
1947                 int head_deleted = !head;
1948                 int remote_deleted = !remote;
1949                 const struct cache_entry *ce = NULL;
1950
1951                 if (index)
1952                         ce = index;
1953                 else if (head)
1954                         ce = head;
1955                 else if (remote)
1956                         ce = remote;
1957                 else {
1958                         for (i = 1; i < o->head_idx; i++) {
1959                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
1960                                         ce = stages[i];
1961                                         break;
1962                                 }
1963                         }
1964                 }
1965
1966                 /*
1967                  * Deleted in both.
1968                  * Deleted in one and unchanged in the other.
1969                  */
1970                 if ((head_deleted && remote_deleted) ||
1971                     (head_deleted && remote && remote_match) ||
1972                     (remote_deleted && head && head_match)) {
1973                         if (index)
1974                                 return deleted_entry(index, index, o);
1975                         if (ce && !head_deleted) {
1976                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1977                                         return -1;
1978                         }
1979                         return 0;
1980                 }
1981                 /*
1982                  * Added in both, identically.
1983                  */
1984                 if (no_anc_exists && head && remote && same(head, remote))
1985                         return merged_entry(head, index, o);
1986
1987         }
1988
1989         /* Below are "no merge" cases, which require that the index be
1990          * up-to-date to avoid the files getting overwritten with
1991          * conflict resolution files.
1992          */
1993         if (index) {
1994                 if (verify_uptodate(index, o))
1995                         return -1;
1996         }
1997
1998         o->nontrivial_merge = 1;
1999
2000         /* #2, #3, #4, #6, #7, #9, #10, #11. */
2001         count = 0;
2002         if (!head_match || !remote_match) {
2003                 for (i = 1; i < o->head_idx; i++) {
2004                         if (stages[i] && stages[i] != o->df_conflict_entry) {
2005                                 keep_entry(stages[i], o);
2006                                 count++;
2007                                 break;
2008                         }
2009                 }
2010         }
2011 #if DBRT_DEBUG
2012         else {
2013                 fprintf(stderr, "read-tree: warning #16 detected\n");
2014                 show_stage_entry(stderr, "head   ", stages[head_match]);
2015                 show_stage_entry(stderr, "remote ", stages[remote_match]);
2016         }
2017 #endif
2018         if (head) { count += keep_entry(head, o); }
2019         if (remote) { count += keep_entry(remote, o); }
2020         return count;
2021 }
2022
2023 /*
2024  * Two-way merge.
2025  *
2026  * The rule is to "carry forward" what is in the index without losing
2027  * information across a "fast-forward", favoring a successful merge
2028  * over a merge failure when it makes sense.  For details of the
2029  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
2030  *
2031  */
2032 int twoway_merge(const struct cache_entry * const *src,
2033                  struct unpack_trees_options *o)
2034 {
2035         const struct cache_entry *current = src[0];
2036         const struct cache_entry *oldtree = src[1];
2037         const struct cache_entry *newtree = src[2];
2038
2039         if (o->merge_size != 2)
2040                 return error("Cannot do a twoway merge of %d trees",
2041                              o->merge_size);
2042
2043         if (oldtree == o->df_conflict_entry)
2044                 oldtree = NULL;
2045         if (newtree == o->df_conflict_entry)
2046                 newtree = NULL;
2047
2048         if (current) {
2049                 if (current->ce_flags & CE_CONFLICTED) {
2050                         if (same(oldtree, newtree) || o->reset) {
2051                                 if (!newtree)
2052                                         return deleted_entry(current, current, o);
2053                                 else
2054                                         return merged_entry(newtree, current, o);
2055                         }
2056                         return reject_merge(current, o);
2057                 } else if ((!oldtree && !newtree) || /* 4 and 5 */
2058                          (!oldtree && newtree &&
2059                           same(current, newtree)) || /* 6 and 7 */
2060                          (oldtree && newtree &&
2061                           same(oldtree, newtree)) || /* 14 and 15 */
2062                          (oldtree && newtree &&
2063                           !same(oldtree, newtree) && /* 18 and 19 */
2064                           same(current, newtree))) {
2065                         return keep_entry(current, o);
2066                 } else if (oldtree && !newtree && same(current, oldtree)) {
2067                         /* 10 or 11 */
2068                         return deleted_entry(oldtree, current, o);
2069                 } else if (oldtree && newtree &&
2070                          same(current, oldtree) && !same(current, newtree)) {
2071                         /* 20 or 21 */
2072                         return merged_entry(newtree, current, o);
2073                 } else
2074                         return reject_merge(current, o);
2075         }
2076         else if (newtree) {
2077                 if (oldtree && !o->initial_checkout) {
2078                         /*
2079                          * deletion of the path was staged;
2080                          */
2081                         if (same(oldtree, newtree))
2082                                 return 1;
2083                         return reject_merge(oldtree, o);
2084                 }
2085                 return merged_entry(newtree, current, o);
2086         }
2087         return deleted_entry(oldtree, current, o);
2088 }
2089
2090 /*
2091  * Bind merge.
2092  *
2093  * Keep the index entries at stage0, collapse stage1 but make sure
2094  * stage0 does not have anything there.
2095  */
2096 int bind_merge(const struct cache_entry * const *src,
2097                struct unpack_trees_options *o)
2098 {
2099         const struct cache_entry *old = src[0];
2100         const struct cache_entry *a = src[1];
2101
2102         if (o->merge_size != 1)
2103                 return error("Cannot do a bind merge of %d trees",
2104                              o->merge_size);
2105         if (a && old)
2106                 return o->gently ? -1 :
2107                         error(ERRORMSG(o, ERROR_BIND_OVERLAP),
2108                               super_prefixed(a->name),
2109                               super_prefixed(old->name));
2110         if (!a)
2111                 return keep_entry(old, o);
2112         else
2113                 return merged_entry(a, NULL, o);
2114 }
2115
2116 /*
2117  * One-way merge.
2118  *
2119  * The rule is:
2120  * - take the stat information from stage0, take the data from stage1
2121  */
2122 int oneway_merge(const struct cache_entry * const *src,
2123                  struct unpack_trees_options *o)
2124 {
2125         const struct cache_entry *old = src[0];
2126         const struct cache_entry *a = src[1];
2127
2128         if (o->merge_size != 1)
2129                 return error("Cannot do a oneway merge of %d trees",
2130                              o->merge_size);
2131
2132         if (!a || a == o->df_conflict_entry)
2133                 return deleted_entry(old, old, o);
2134
2135         if (old && same(old, a)) {
2136                 int update = 0;
2137                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
2138                         struct stat st;
2139                         if (lstat(old->name, &st) ||
2140                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
2141                                 update |= CE_UPDATE;
2142                 }
2143                 add_entry(o, old, update, 0);
2144                 return 0;
2145         }
2146         return merged_entry(a, old, o);
2147 }