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