Merge branch 'lv/tls-1.3'
[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 #include "fetch-object.h"
19
20 /*
21  * Error messages expected by scripts out of plumbing commands such as
22  * read-tree.  Non-scripted Porcelain is not required to use these messages
23  * and in fact are encouraged to reword them to better suit their particular
24  * situation better.  See how "git checkout" and "git merge" replaces
25  * them using setup_unpack_trees_porcelain(), for example.
26  */
27 static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
28         /* ERROR_WOULD_OVERWRITE */
29         "Entry '%s' would be overwritten by merge. Cannot merge.",
30
31         /* ERROR_NOT_UPTODATE_FILE */
32         "Entry '%s' not uptodate. Cannot merge.",
33
34         /* ERROR_NOT_UPTODATE_DIR */
35         "Updating '%s' would lose untracked files in it",
36
37         /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
38         "Untracked working tree file '%s' would be overwritten by merge.",
39
40         /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
41         "Untracked working tree file '%s' would be removed by merge.",
42
43         /* ERROR_BIND_OVERLAP */
44         "Entry '%s' overlaps with '%s'.  Cannot bind.",
45
46         /* ERROR_SPARSE_NOT_UPTODATE_FILE */
47         "Entry '%s' not uptodate. Cannot update sparse checkout.",
48
49         /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
50         "Working tree file '%s' would be overwritten by sparse checkout update.",
51
52         /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
53         "Working tree file '%s' would be removed by sparse checkout update.",
54
55         /* ERROR_WOULD_LOSE_SUBMODULE */
56         "Submodule '%s' cannot checkout new HEAD.",
57 };
58
59 #define ERRORMSG(o,type) \
60         ( ((o) && (o)->msgs[(type)]) \
61           ? ((o)->msgs[(type)])      \
62           : (unpack_plumbing_errors[(type)]) )
63
64 static const char *super_prefixed(const char *path)
65 {
66         /*
67          * It is necessary and sufficient to have two static buffers
68          * here, as the return value of this function is fed to
69          * error() using the unpack_*_errors[] templates we see above.
70          */
71         static struct strbuf buf[2] = {STRBUF_INIT, STRBUF_INIT};
72         static int super_prefix_len = -1;
73         static unsigned idx = ARRAY_SIZE(buf) - 1;
74
75         if (super_prefix_len < 0) {
76                 const char *super_prefix = get_super_prefix();
77                 if (!super_prefix) {
78                         super_prefix_len = 0;
79                 } else {
80                         int i;
81                         for (i = 0; i < ARRAY_SIZE(buf); i++)
82                                 strbuf_addstr(&buf[i], super_prefix);
83                         super_prefix_len = buf[0].len;
84                 }
85         }
86
87         if (!super_prefix_len)
88                 return path;
89
90         if (++idx >= ARRAY_SIZE(buf))
91                 idx = 0;
92
93         strbuf_setlen(&buf[idx], super_prefix_len);
94         strbuf_addstr(&buf[idx], path);
95
96         return buf[idx].buf;
97 }
98
99 void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
100                                   const char *cmd)
101 {
102         int i;
103         const char **msgs = opts->msgs;
104         const char *msg;
105
106         if (!strcmp(cmd, "checkout"))
107                 msg = advice_commit_before_merge
108                       ? _("Your local changes to the following files would be overwritten by checkout:\n%%s"
109                           "Please commit your changes or stash them before you switch branches.")
110                       : _("Your local changes to the following files would be overwritten by checkout:\n%%s");
111         else if (!strcmp(cmd, "merge"))
112                 msg = advice_commit_before_merge
113                       ? _("Your local changes to the following files would be overwritten by merge:\n%%s"
114                           "Please commit your changes or stash them before you merge.")
115                       : _("Your local changes to the following files would be overwritten by merge:\n%%s");
116         else
117                 msg = advice_commit_before_merge
118                       ? _("Your local changes to the following files would be overwritten by %s:\n%%s"
119                           "Please commit your changes or stash them before you %s.")
120                       : _("Your local changes to the following files would be overwritten by %s:\n%%s");
121         msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
122                 xstrfmt(msg, cmd, cmd);
123
124         msgs[ERROR_NOT_UPTODATE_DIR] =
125                 _("Updating the following directories would lose untracked files in them:\n%s");
126
127         if (!strcmp(cmd, "checkout"))
128                 msg = advice_commit_before_merge
129                       ? _("The following untracked working tree files would be removed by checkout:\n%%s"
130                           "Please move or remove them before you switch branches.")
131                       : _("The following untracked working tree files would be removed by checkout:\n%%s");
132         else if (!strcmp(cmd, "merge"))
133                 msg = advice_commit_before_merge
134                       ? _("The following untracked working tree files would be removed by merge:\n%%s"
135                           "Please move or remove them before you merge.")
136                       : _("The following untracked working tree files would be removed by merge:\n%%s");
137         else
138                 msg = advice_commit_before_merge
139                       ? _("The following untracked working tree files would be removed by %s:\n%%s"
140                           "Please move or remove them before you %s.")
141                       : _("The following untracked working tree files would be removed by %s:\n%%s");
142         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = xstrfmt(msg, cmd, cmd);
143
144         if (!strcmp(cmd, "checkout"))
145                 msg = advice_commit_before_merge
146                       ? _("The following untracked working tree files would be overwritten by checkout:\n%%s"
147                           "Please move or remove them before you switch branches.")
148                       : _("The following untracked working tree files would be overwritten by checkout:\n%%s");
149         else if (!strcmp(cmd, "merge"))
150                 msg = advice_commit_before_merge
151                       ? _("The following untracked working tree files would be overwritten by merge:\n%%s"
152                           "Please move or remove them before you merge.")
153                       : _("The following untracked working tree files would be overwritten by merge:\n%%s");
154         else
155                 msg = advice_commit_before_merge
156                       ? _("The following untracked working tree files would be overwritten by %s:\n%%s"
157                           "Please move or remove them before you %s.")
158                       : _("The following untracked working tree files would be overwritten by %s:\n%%s");
159         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = xstrfmt(msg, cmd, cmd);
160
161         /*
162          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
163          * cannot easily display it as a list.
164          */
165         msgs[ERROR_BIND_OVERLAP] = _("Entry '%s' overlaps with '%s'.  Cannot bind.");
166
167         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
168                 _("Cannot update sparse checkout: the following entries are not up to date:\n%s");
169         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
170                 _("The following working tree files would be overwritten by sparse checkout update:\n%s");
171         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
172                 _("The following working tree files would be removed by sparse checkout update:\n%s");
173         msgs[ERROR_WOULD_LOSE_SUBMODULE] =
174                 _("Cannot update submodule:\n%s");
175
176         opts->show_all_errors = 1;
177         /* rejected paths may not have a static buffer */
178         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
179                 opts->unpack_rejects[i].strdup_strings = 1;
180 }
181
182 static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
183                          unsigned int set, unsigned int clear)
184 {
185         clear |= CE_HASHED;
186
187         if (set & CE_REMOVE)
188                 set |= CE_WT_REMOVE;
189
190         ce->ce_flags = (ce->ce_flags & ~clear) | set;
191         return add_index_entry(&o->result, ce,
192                                ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
193 }
194
195 static struct cache_entry *dup_entry(const struct cache_entry *ce)
196 {
197         unsigned int size = ce_size(ce);
198         struct cache_entry *new_entry = xmalloc(size);
199
200         memcpy(new_entry, ce, size);
201         return new_entry;
202 }
203
204 static void add_entry(struct unpack_trees_options *o,
205                       const struct cache_entry *ce,
206                       unsigned int set, unsigned int clear)
207 {
208         do_add_entry(o, dup_entry(ce), set, clear);
209 }
210
211 /*
212  * add error messages on path <path>
213  * corresponding to the type <e> with the message <msg>
214  * indicating if it should be display in porcelain or not
215  */
216 static int add_rejected_path(struct unpack_trees_options *o,
217                              enum unpack_trees_error_types e,
218                              const char *path)
219 {
220         if (!o->show_all_errors)
221                 return error(ERRORMSG(o, e), super_prefixed(path));
222
223         /*
224          * Otherwise, insert in a list for future display by
225          * display_error_msgs()
226          */
227         string_list_append(&o->unpack_rejects[e], path);
228         return -1;
229 }
230
231 /*
232  * display all the error messages stored in a nice way
233  */
234 static void display_error_msgs(struct unpack_trees_options *o)
235 {
236         int e, i;
237         int something_displayed = 0;
238         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
239                 struct string_list *rejects = &o->unpack_rejects[e];
240                 if (rejects->nr > 0) {
241                         struct strbuf path = STRBUF_INIT;
242                         something_displayed = 1;
243                         for (i = 0; i < rejects->nr; i++)
244                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
245                         error(ERRORMSG(o, e), super_prefixed(path.buf));
246                         strbuf_release(&path);
247                 }
248                 string_list_clear(rejects, 0);
249         }
250         if (something_displayed)
251                 fprintf(stderr, _("Aborting\n"));
252 }
253
254 static int check_submodule_move_head(const struct cache_entry *ce,
255                                      const char *old_id,
256                                      const char *new_id,
257                                      struct unpack_trees_options *o)
258 {
259         unsigned flags = SUBMODULE_MOVE_HEAD_DRY_RUN;
260         const struct submodule *sub = submodule_from_ce(ce);
261
262         if (!sub)
263                 return 0;
264
265         if (o->reset)
266                 flags |= SUBMODULE_MOVE_HEAD_FORCE;
267
268         if (submodule_move_head(ce->name, old_id, new_id, flags))
269                 return o->gently ? -1 :
270                                    add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
271         return 0;
272 }
273
274 /*
275  * Preform the loading of the repository's gitmodules file.  This function is
276  * used by 'check_update()' to perform loading of the gitmodules file in two
277  * differnt situations:
278  * (1) before removing entries from the working tree if the gitmodules file has
279  *     been marked for removal.  This situation is specified by 'state' == NULL.
280  * (2) before checking out entries to the working tree if the gitmodules file
281  *     has been marked for update.  This situation is specified by 'state' != NULL.
282  */
283 static void load_gitmodules_file(struct index_state *index,
284                                  struct checkout *state)
285 {
286         int pos = index_name_pos(index, GITMODULES_FILE, strlen(GITMODULES_FILE));
287
288         if (pos >= 0) {
289                 struct cache_entry *ce = index->cache[pos];
290                 if (!state && ce->ce_flags & CE_WT_REMOVE) {
291                         repo_read_gitmodules(the_repository);
292                 } else if (state && (ce->ce_flags & CE_UPDATE)) {
293                         submodule_free();
294                         checkout_entry(ce, state, NULL);
295                         repo_read_gitmodules(the_repository);
296                 }
297         }
298 }
299
300 /*
301  * Unlink the last component and schedule the leading directories for
302  * removal, such that empty directories get removed.
303  */
304 static void unlink_entry(const struct cache_entry *ce)
305 {
306         const struct submodule *sub = submodule_from_ce(ce);
307         if (sub) {
308                 /* state.force is set at the caller. */
309                 submodule_move_head(ce->name, "HEAD", NULL,
310                                     SUBMODULE_MOVE_HEAD_FORCE);
311         }
312         if (!check_leading_path(ce->name, ce_namelen(ce)))
313                 return;
314         if (remove_or_warn(ce->ce_mode, ce->name))
315                 return;
316         schedule_dir_for_removal(ce->name, ce_namelen(ce));
317 }
318
319 static struct progress *get_progress(struct unpack_trees_options *o)
320 {
321         unsigned cnt = 0, total = 0;
322         struct index_state *index = &o->result;
323
324         if (!o->update || !o->verbose_update)
325                 return NULL;
326
327         for (; cnt < index->cache_nr; cnt++) {
328                 const struct cache_entry *ce = index->cache[cnt];
329                 if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
330                         total++;
331         }
332
333         return start_delayed_progress(_("Checking out files"), total);
334 }
335
336 static int check_updates(struct unpack_trees_options *o)
337 {
338         unsigned cnt = 0;
339         int errs = 0;
340         struct progress *progress = NULL;
341         struct index_state *index = &o->result;
342         struct checkout state = CHECKOUT_INIT;
343         int i;
344
345         state.force = 1;
346         state.quiet = 1;
347         state.refresh_cache = 1;
348         state.istate = index;
349
350         progress = get_progress(o);
351
352         if (o->update)
353                 git_attr_set_direction(GIT_ATTR_CHECKOUT, index);
354
355         if (should_update_submodules() && o->update && !o->dry_run)
356                 load_gitmodules_file(index, NULL);
357
358         for (i = 0; i < index->cache_nr; i++) {
359                 const struct cache_entry *ce = index->cache[i];
360
361                 if (ce->ce_flags & CE_WT_REMOVE) {
362                         display_progress(progress, ++cnt);
363                         if (o->update && !o->dry_run)
364                                 unlink_entry(ce);
365                 }
366         }
367         remove_marked_cache_entries(index);
368         remove_scheduled_dirs();
369
370         if (should_update_submodules() && o->update && !o->dry_run)
371                 load_gitmodules_file(index, &state);
372
373         enable_delayed_checkout(&state);
374         if (repository_format_partial_clone && o->update && !o->dry_run) {
375                 /*
376                  * Prefetch the objects that are to be checked out in the loop
377                  * below.
378                  */
379                 struct oid_array to_fetch = OID_ARRAY_INIT;
380                 int fetch_if_missing_store = fetch_if_missing;
381                 fetch_if_missing = 0;
382                 for (i = 0; i < index->cache_nr; i++) {
383                         struct cache_entry *ce = index->cache[i];
384                         if ((ce->ce_flags & CE_UPDATE) &&
385                             !S_ISGITLINK(ce->ce_mode)) {
386                                 if (!has_object_file(&ce->oid))
387                                         oid_array_append(&to_fetch, &ce->oid);
388                         }
389                 }
390                 if (to_fetch.nr)
391                         fetch_objects(repository_format_partial_clone,
392                                       &to_fetch);
393                 fetch_if_missing = fetch_if_missing_store;
394                 oid_array_clear(&to_fetch);
395         }
396         for (i = 0; i < index->cache_nr; i++) {
397                 struct cache_entry *ce = index->cache[i];
398
399                 if (ce->ce_flags & CE_UPDATE) {
400                         if (ce->ce_flags & CE_WT_REMOVE)
401                                 die("BUG: both update and delete flags are set on %s",
402                                     ce->name);
403                         display_progress(progress, ++cnt);
404                         ce->ce_flags &= ~CE_UPDATE;
405                         if (o->update && !o->dry_run) {
406                                 errs |= checkout_entry(ce, &state, NULL);
407                         }
408                 }
409         }
410         stop_progress(&progress);
411         errs |= finish_delayed_checkout(&state);
412         if (o->update)
413                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
414         return errs != 0;
415 }
416
417 static int verify_uptodate_sparse(const struct cache_entry *ce,
418                                   struct unpack_trees_options *o);
419 static int verify_absent_sparse(const struct cache_entry *ce,
420                                 enum unpack_trees_error_types,
421                                 struct unpack_trees_options *o);
422
423 static int apply_sparse_checkout(struct index_state *istate,
424                                  struct cache_entry *ce,
425                                  struct unpack_trees_options *o)
426 {
427         int was_skip_worktree = ce_skip_worktree(ce);
428
429         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
430                 ce->ce_flags |= CE_SKIP_WORKTREE;
431         else
432                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
433         if (was_skip_worktree != ce_skip_worktree(ce)) {
434                 ce->ce_flags |= CE_UPDATE_IN_BASE;
435                 mark_fsmonitor_invalid(istate, ce);
436                 istate->cache_changed |= CE_ENTRY_CHANGED;
437         }
438
439         /*
440          * if (!was_skip_worktree && !ce_skip_worktree()) {
441          *      This is perfectly normal. Move on;
442          * }
443          */
444
445         /*
446          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
447          * area as a result of ce_skip_worktree() shortcuts in
448          * verify_absent() and verify_uptodate().
449          * Make sure they don't modify worktree if they are already
450          * outside checkout area
451          */
452         if (was_skip_worktree && ce_skip_worktree(ce)) {
453                 ce->ce_flags &= ~CE_UPDATE;
454
455                 /*
456                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
457                  * on to get that file removed from both index and worktree.
458                  * If that file is already outside worktree area, don't
459                  * bother remove it.
460                  */
461                 if (ce->ce_flags & CE_REMOVE)
462                         ce->ce_flags &= ~CE_WT_REMOVE;
463         }
464
465         if (!was_skip_worktree && ce_skip_worktree(ce)) {
466                 /*
467                  * If CE_UPDATE is set, verify_uptodate() must be called already
468                  * also stat info may have lost after merged_entry() so calling
469                  * verify_uptodate() again may fail
470                  */
471                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
472                         return -1;
473                 ce->ce_flags |= CE_WT_REMOVE;
474                 ce->ce_flags &= ~CE_UPDATE;
475         }
476         if (was_skip_worktree && !ce_skip_worktree(ce)) {
477                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
478                         return -1;
479                 ce->ce_flags |= CE_UPDATE;
480         }
481         return 0;
482 }
483
484 static inline int call_unpack_fn(const struct cache_entry * const *src,
485                                  struct unpack_trees_options *o)
486 {
487         int ret = o->fn(src, o);
488         if (ret > 0)
489                 ret = 0;
490         return ret;
491 }
492
493 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
494 {
495         ce->ce_flags |= CE_UNPACKED;
496
497         if (o->cache_bottom < o->src_index->cache_nr &&
498             o->src_index->cache[o->cache_bottom] == ce) {
499                 int bottom = o->cache_bottom;
500                 while (bottom < o->src_index->cache_nr &&
501                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
502                         bottom++;
503                 o->cache_bottom = bottom;
504         }
505 }
506
507 static void mark_all_ce_unused(struct index_state *index)
508 {
509         int i;
510         for (i = 0; i < index->cache_nr; i++)
511                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
512 }
513
514 static int locate_in_src_index(const struct cache_entry *ce,
515                                struct unpack_trees_options *o)
516 {
517         struct index_state *index = o->src_index;
518         int len = ce_namelen(ce);
519         int pos = index_name_pos(index, ce->name, len);
520         if (pos < 0)
521                 pos = -1 - pos;
522         return pos;
523 }
524
525 /*
526  * We call unpack_index_entry() with an unmerged cache entry
527  * only in diff-index, and it wants a single callback.  Skip
528  * the other unmerged entry with the same name.
529  */
530 static void mark_ce_used_same_name(struct cache_entry *ce,
531                                    struct unpack_trees_options *o)
532 {
533         struct index_state *index = o->src_index;
534         int len = ce_namelen(ce);
535         int pos;
536
537         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
538                 struct cache_entry *next = index->cache[pos];
539                 if (len != ce_namelen(next) ||
540                     memcmp(ce->name, next->name, len))
541                         break;
542                 mark_ce_used(next, o);
543         }
544 }
545
546 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
547 {
548         const struct index_state *index = o->src_index;
549         int pos = o->cache_bottom;
550
551         while (pos < index->cache_nr) {
552                 struct cache_entry *ce = index->cache[pos];
553                 if (!(ce->ce_flags & CE_UNPACKED))
554                         return ce;
555                 pos++;
556         }
557         return NULL;
558 }
559
560 static void add_same_unmerged(const struct cache_entry *ce,
561                               struct unpack_trees_options *o)
562 {
563         struct index_state *index = o->src_index;
564         int len = ce_namelen(ce);
565         int pos = index_name_pos(index, ce->name, len);
566
567         if (0 <= pos)
568                 die("programming error in a caller of mark_ce_used_same_name");
569         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
570                 struct cache_entry *next = index->cache[pos];
571                 if (len != ce_namelen(next) ||
572                     memcmp(ce->name, next->name, len))
573                         break;
574                 add_entry(o, next, 0, 0);
575                 mark_ce_used(next, o);
576         }
577 }
578
579 static int unpack_index_entry(struct cache_entry *ce,
580                               struct unpack_trees_options *o)
581 {
582         const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
583         int ret;
584
585         src[0] = ce;
586
587         mark_ce_used(ce, o);
588         if (ce_stage(ce)) {
589                 if (o->skip_unmerged) {
590                         add_entry(o, ce, 0, 0);
591                         return 0;
592                 }
593         }
594         ret = call_unpack_fn(src, o);
595         if (ce_stage(ce))
596                 mark_ce_used_same_name(ce, o);
597         return ret;
598 }
599
600 static int find_cache_pos(struct traverse_info *, const struct name_entry *);
601
602 static void restore_cache_bottom(struct traverse_info *info, int bottom)
603 {
604         struct unpack_trees_options *o = info->data;
605
606         if (o->diff_index_cached)
607                 return;
608         o->cache_bottom = bottom;
609 }
610
611 static int switch_cache_bottom(struct traverse_info *info)
612 {
613         struct unpack_trees_options *o = info->data;
614         int ret, pos;
615
616         if (o->diff_index_cached)
617                 return 0;
618         ret = o->cache_bottom;
619         pos = find_cache_pos(info->prev, &info->name);
620
621         if (pos < -1)
622                 o->cache_bottom = -2 - pos;
623         else if (pos < 0)
624                 o->cache_bottom = o->src_index->cache_nr;
625         return ret;
626 }
627
628 static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
629 {
630         return name_j->oid && name_k->oid && !oidcmp(name_j->oid, name_k->oid);
631 }
632
633 static int traverse_trees_recursive(int n, unsigned long dirmask,
634                                     unsigned long df_conflicts,
635                                     struct name_entry *names,
636                                     struct traverse_info *info)
637 {
638         int i, ret, bottom;
639         int nr_buf = 0;
640         struct tree_desc t[MAX_UNPACK_TREES];
641         void *buf[MAX_UNPACK_TREES];
642         struct traverse_info newinfo;
643         struct name_entry *p;
644
645         p = names;
646         while (!p->mode)
647                 p++;
648
649         newinfo = *info;
650         newinfo.prev = info;
651         newinfo.pathspec = info->pathspec;
652         newinfo.name = *p;
653         newinfo.pathlen += tree_entry_len(p) + 1;
654         newinfo.df_conflicts |= df_conflicts;
655
656         /*
657          * Fetch the tree from the ODB for each peer directory in the
658          * n commits.
659          *
660          * For 2- and 3-way traversals, we try to avoid hitting the
661          * ODB twice for the same OID.  This should yield a nice speed
662          * up in checkouts and merges when the commits are similar.
663          *
664          * We don't bother doing the full O(n^2) search for larger n,
665          * because wider traversals don't happen that often and we
666          * avoid the search setup.
667          *
668          * When 2 peer OIDs are the same, we just copy the tree
669          * descriptor data.  This implicitly borrows the buffer
670          * data from the earlier cell.
671          */
672         for (i = 0; i < n; i++, dirmask >>= 1) {
673                 if (i > 0 && are_same_oid(&names[i], &names[i - 1]))
674                         t[i] = t[i - 1];
675                 else if (i > 1 && are_same_oid(&names[i], &names[i - 2]))
676                         t[i] = t[i - 2];
677                 else {
678                         const struct object_id *oid = NULL;
679                         if (dirmask & 1)
680                                 oid = names[i].oid;
681                         buf[nr_buf++] = fill_tree_descriptor(t + i, oid);
682                 }
683         }
684
685         bottom = switch_cache_bottom(&newinfo);
686         ret = traverse_trees(n, t, &newinfo);
687         restore_cache_bottom(&newinfo, bottom);
688
689         for (i = 0; i < nr_buf; i++)
690                 free(buf[i]);
691
692         return ret;
693 }
694
695 /*
696  * Compare the traverse-path to the cache entry without actually
697  * having to generate the textual representation of the traverse
698  * path.
699  *
700  * NOTE! This *only* compares up to the size of the traverse path
701  * itself - the caller needs to do the final check for the cache
702  * entry having more data at the end!
703  */
704 static int do_compare_entry_piecewise(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
705 {
706         int len, pathlen, ce_len;
707         const char *ce_name;
708
709         if (info->prev) {
710                 int cmp = do_compare_entry_piecewise(ce, info->prev,
711                                                      &info->name);
712                 if (cmp)
713                         return cmp;
714         }
715         pathlen = info->pathlen;
716         ce_len = ce_namelen(ce);
717
718         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
719         if (ce_len < pathlen)
720                 return -1;
721
722         ce_len -= pathlen;
723         ce_name = ce->name + pathlen;
724
725         len = tree_entry_len(n);
726         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
727 }
728
729 static int do_compare_entry(const struct cache_entry *ce,
730                             const struct traverse_info *info,
731                             const struct name_entry *n)
732 {
733         int len, pathlen, ce_len;
734         const char *ce_name;
735         int cmp;
736
737         /*
738          * If we have not precomputed the traverse path, it is quicker
739          * to avoid doing so.  But if we have precomputed it,
740          * it is quicker to use the precomputed version.
741          */
742         if (!info->traverse_path)
743                 return do_compare_entry_piecewise(ce, info, n);
744
745         cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
746         if (cmp)
747                 return cmp;
748
749         pathlen = info->pathlen;
750         ce_len = ce_namelen(ce);
751
752         if (ce_len < pathlen)
753                 return -1;
754
755         ce_len -= pathlen;
756         ce_name = ce->name + pathlen;
757
758         len = tree_entry_len(n);
759         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
760 }
761
762 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
763 {
764         int cmp = do_compare_entry(ce, info, n);
765         if (cmp)
766                 return cmp;
767
768         /*
769          * Even if the beginning compared identically, the ce should
770          * compare as bigger than a directory leading up to it!
771          */
772         return ce_namelen(ce) > traverse_path_len(info, n);
773 }
774
775 static int ce_in_traverse_path(const struct cache_entry *ce,
776                                const struct traverse_info *info)
777 {
778         if (!info->prev)
779                 return 1;
780         if (do_compare_entry(ce, info->prev, &info->name))
781                 return 0;
782         /*
783          * If ce (blob) is the same name as the path (which is a tree
784          * we will be descending into), it won't be inside it.
785          */
786         return (info->pathlen < ce_namelen(ce));
787 }
788
789 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
790 {
791         int len = traverse_path_len(info, n);
792         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
793
794         ce->ce_mode = create_ce_mode(n->mode);
795         ce->ce_flags = create_ce_flags(stage);
796         ce->ce_namelen = len;
797         oidcpy(&ce->oid, n->oid);
798         make_traverse_path(ce->name, info, n);
799
800         return ce;
801 }
802
803 static int unpack_nondirectories(int n, unsigned long mask,
804                                  unsigned long dirmask,
805                                  struct cache_entry **src,
806                                  const struct name_entry *names,
807                                  const struct traverse_info *info)
808 {
809         int i;
810         struct unpack_trees_options *o = info->data;
811         unsigned long conflicts = info->df_conflicts | dirmask;
812
813         /* Do we have *only* directories? Nothing to do */
814         if (mask == dirmask && !src[0])
815                 return 0;
816
817         /*
818          * Ok, we've filled in up to any potential index entry in src[0],
819          * now do the rest.
820          */
821         for (i = 0; i < n; i++) {
822                 int stage;
823                 unsigned int bit = 1ul << i;
824                 if (conflicts & bit) {
825                         src[i + o->merge] = o->df_conflict_entry;
826                         continue;
827                 }
828                 if (!(mask & bit))
829                         continue;
830                 if (!o->merge)
831                         stage = 0;
832                 else if (i + 1 < o->head_idx)
833                         stage = 1;
834                 else if (i + 1 > o->head_idx)
835                         stage = 3;
836                 else
837                         stage = 2;
838                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
839         }
840
841         if (o->merge) {
842                 int rc = call_unpack_fn((const struct cache_entry * const *)src,
843                                         o);
844                 for (i = 0; i < n; i++) {
845                         struct cache_entry *ce = src[i + o->merge];
846                         if (ce != o->df_conflict_entry)
847                                 free(ce);
848                 }
849                 return rc;
850         }
851
852         for (i = 0; i < n; i++)
853                 if (src[i] && src[i] != o->df_conflict_entry)
854                         if (do_add_entry(o, src[i], 0, 0))
855                                 return -1;
856
857         return 0;
858 }
859
860 static int unpack_failed(struct unpack_trees_options *o, const char *message)
861 {
862         discard_index(&o->result);
863         if (!o->gently && !o->exiting_early) {
864                 if (message)
865                         return error("%s", message);
866                 return -1;
867         }
868         return -1;
869 }
870
871 /*
872  * The tree traversal is looking at name p.  If we have a matching entry,
873  * return it.  If name p is a directory in the index, do not return
874  * anything, as we will want to match it when the traversal descends into
875  * the directory.
876  */
877 static int find_cache_pos(struct traverse_info *info,
878                           const struct name_entry *p)
879 {
880         int pos;
881         struct unpack_trees_options *o = info->data;
882         struct index_state *index = o->src_index;
883         int pfxlen = info->pathlen;
884         int p_len = tree_entry_len(p);
885
886         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
887                 const struct cache_entry *ce = index->cache[pos];
888                 const char *ce_name, *ce_slash;
889                 int cmp, ce_len;
890
891                 if (ce->ce_flags & CE_UNPACKED) {
892                         /*
893                          * cache_bottom entry is already unpacked, so
894                          * we can never match it; don't check it
895                          * again.
896                          */
897                         if (pos == o->cache_bottom)
898                                 ++o->cache_bottom;
899                         continue;
900                 }
901                 if (!ce_in_traverse_path(ce, info)) {
902                         /*
903                          * Check if we can skip future cache checks
904                          * (because we're already past all possible
905                          * entries in the traverse path).
906                          */
907                         if (info->traverse_path) {
908                                 if (strncmp(ce->name, info->traverse_path,
909                                             info->pathlen) > 0)
910                                         break;
911                         }
912                         continue;
913                 }
914                 ce_name = ce->name + pfxlen;
915                 ce_slash = strchr(ce_name, '/');
916                 if (ce_slash)
917                         ce_len = ce_slash - ce_name;
918                 else
919                         ce_len = ce_namelen(ce) - pfxlen;
920                 cmp = name_compare(p->path, p_len, ce_name, ce_len);
921                 /*
922                  * Exact match; if we have a directory we need to
923                  * delay returning it.
924                  */
925                 if (!cmp)
926                         return ce_slash ? -2 - pos : pos;
927                 if (0 < cmp)
928                         continue; /* keep looking */
929                 /*
930                  * ce_name sorts after p->path; could it be that we
931                  * have files under p->path directory in the index?
932                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
933                  * have "t/a" in the index.
934                  */
935                 if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
936                     ce_name[p_len] < '/')
937                         continue; /* keep looking */
938                 break;
939         }
940         return -1;
941 }
942
943 static struct cache_entry *find_cache_entry(struct traverse_info *info,
944                                             const struct name_entry *p)
945 {
946         int pos = find_cache_pos(info, p);
947         struct unpack_trees_options *o = info->data;
948
949         if (0 <= pos)
950                 return o->src_index->cache[pos];
951         else
952                 return NULL;
953 }
954
955 static void debug_path(struct traverse_info *info)
956 {
957         if (info->prev) {
958                 debug_path(info->prev);
959                 if (*info->prev->name.path)
960                         putchar('/');
961         }
962         printf("%s", info->name.path);
963 }
964
965 static void debug_name_entry(int i, struct name_entry *n)
966 {
967         printf("ent#%d %06o %s\n", i,
968                n->path ? n->mode : 0,
969                n->path ? n->path : "(missing)");
970 }
971
972 static void debug_unpack_callback(int n,
973                                   unsigned long mask,
974                                   unsigned long dirmask,
975                                   struct name_entry *names,
976                                   struct traverse_info *info)
977 {
978         int i;
979         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
980                mask, dirmask, n);
981         debug_path(info);
982         putchar('\n');
983         for (i = 0; i < n; i++)
984                 debug_name_entry(i, names + i);
985 }
986
987 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
988 {
989         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
990         struct unpack_trees_options *o = info->data;
991         const struct name_entry *p = names;
992
993         /* Find first entry with a real name (we could use "mask" too) */
994         while (!p->mode)
995                 p++;
996
997         if (o->debug_unpack)
998                 debug_unpack_callback(n, mask, dirmask, names, info);
999
1000         /* Are we supposed to look at the index too? */
1001         if (o->merge) {
1002                 while (1) {
1003                         int cmp;
1004                         struct cache_entry *ce;
1005
1006                         if (o->diff_index_cached)
1007                                 ce = next_cache_entry(o);
1008                         else
1009                                 ce = find_cache_entry(info, p);
1010
1011                         if (!ce)
1012                                 break;
1013                         cmp = compare_entry(ce, info, p);
1014                         if (cmp < 0) {
1015                                 if (unpack_index_entry(ce, o) < 0)
1016                                         return unpack_failed(o, NULL);
1017                                 continue;
1018                         }
1019                         if (!cmp) {
1020                                 if (ce_stage(ce)) {
1021                                         /*
1022                                          * If we skip unmerged index
1023                                          * entries, we'll skip this
1024                                          * entry *and* the tree
1025                                          * entries associated with it!
1026                                          */
1027                                         if (o->skip_unmerged) {
1028                                                 add_same_unmerged(ce, o);
1029                                                 return mask;
1030                                         }
1031                                 }
1032                                 src[0] = ce;
1033                         }
1034                         break;
1035                 }
1036         }
1037
1038         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
1039                 return -1;
1040
1041         if (o->merge && src[0]) {
1042                 if (ce_stage(src[0]))
1043                         mark_ce_used_same_name(src[0], o);
1044                 else
1045                         mark_ce_used(src[0], o);
1046         }
1047
1048         /* Now handle any directories.. */
1049         if (dirmask) {
1050                 /* special case: "diff-index --cached" looking at a tree */
1051                 if (o->diff_index_cached &&
1052                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
1053                         int matches;
1054                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
1055                                                                names, info);
1056                         /*
1057                          * Everything under the name matches; skip the
1058                          * entire hierarchy.  diff_index_cached codepath
1059                          * special cases D/F conflicts in such a way that
1060                          * it does not do any look-ahead, so this is safe.
1061                          */
1062                         if (matches) {
1063                                 o->cache_bottom += matches;
1064                                 return mask;
1065                         }
1066                 }
1067
1068                 if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
1069                                              names, info) < 0)
1070                         return -1;
1071                 return mask;
1072         }
1073
1074         return mask;
1075 }
1076
1077 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
1078                             struct strbuf *prefix,
1079                             int select_mask, int clear_mask,
1080                             struct exclude_list *el, int defval);
1081
1082 /* Whole directory matching */
1083 static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
1084                               struct strbuf *prefix,
1085                               char *basename,
1086                               int select_mask, int clear_mask,
1087                               struct exclude_list *el, int defval)
1088 {
1089         struct cache_entry **cache_end;
1090         int dtype = DT_DIR;
1091         int ret = is_excluded_from_list(prefix->buf, prefix->len,
1092                                         basename, &dtype, el, &the_index);
1093         int rc;
1094
1095         strbuf_addch(prefix, '/');
1096
1097         /* If undecided, use matching result of parent dir in defval */
1098         if (ret < 0)
1099                 ret = defval;
1100
1101         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
1102                 struct cache_entry *ce = *cache_end;
1103                 if (strncmp(ce->name, prefix->buf, prefix->len))
1104                         break;
1105         }
1106
1107         /*
1108          * TODO: check el, if there are no patterns that may conflict
1109          * with ret (iow, we know in advance the incl/excl
1110          * decision for the entire directory), clear flag here without
1111          * calling clear_ce_flags_1(). That function will call
1112          * the expensive is_excluded_from_list() on every entry.
1113          */
1114         rc = clear_ce_flags_1(cache, cache_end - cache,
1115                               prefix,
1116                               select_mask, clear_mask,
1117                               el, ret);
1118         strbuf_setlen(prefix, prefix->len - 1);
1119         return rc;
1120 }
1121
1122 /*
1123  * Traverse the index, find every entry that matches according to
1124  * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
1125  * number of traversed entries.
1126  *
1127  * If select_mask is non-zero, only entries whose ce_flags has on of
1128  * those bits enabled are traversed.
1129  *
1130  * cache        : pointer to an index entry
1131  * prefix_len   : an offset to its path
1132  *
1133  * The current path ("prefix") including the trailing '/' is
1134  *   cache[0]->name[0..(prefix_len-1)]
1135  * Top level path has prefix_len zero.
1136  */
1137 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
1138                             struct strbuf *prefix,
1139                             int select_mask, int clear_mask,
1140                             struct exclude_list *el, int defval)
1141 {
1142         struct cache_entry **cache_end = cache + nr;
1143
1144         /*
1145          * Process all entries that have the given prefix and meet
1146          * select_mask condition
1147          */
1148         while(cache != cache_end) {
1149                 struct cache_entry *ce = *cache;
1150                 const char *name, *slash;
1151                 int len, dtype, ret;
1152
1153                 if (select_mask && !(ce->ce_flags & select_mask)) {
1154                         cache++;
1155                         continue;
1156                 }
1157
1158                 if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
1159                         break;
1160
1161                 name = ce->name + prefix->len;
1162                 slash = strchr(name, '/');
1163
1164                 /* If it's a directory, try whole directory match first */
1165                 if (slash) {
1166                         int processed;
1167
1168                         len = slash - name;
1169                         strbuf_add(prefix, name, len);
1170
1171                         processed = clear_ce_flags_dir(cache, cache_end - cache,
1172                                                        prefix,
1173                                                        prefix->buf + prefix->len - len,
1174                                                        select_mask, clear_mask,
1175                                                        el, defval);
1176
1177                         /* clear_c_f_dir eats a whole dir already? */
1178                         if (processed) {
1179                                 cache += processed;
1180                                 strbuf_setlen(prefix, prefix->len - len);
1181                                 continue;
1182                         }
1183
1184                         strbuf_addch(prefix, '/');
1185                         cache += clear_ce_flags_1(cache, cache_end - cache,
1186                                                   prefix,
1187                                                   select_mask, clear_mask, el, defval);
1188                         strbuf_setlen(prefix, prefix->len - len - 1);
1189                         continue;
1190                 }
1191
1192                 /* Non-directory */
1193                 dtype = ce_to_dtype(ce);
1194                 ret = is_excluded_from_list(ce->name, ce_namelen(ce),
1195                                             name, &dtype, el, &the_index);
1196                 if (ret < 0)
1197                         ret = defval;
1198                 if (ret > 0)
1199                         ce->ce_flags &= ~clear_mask;
1200                 cache++;
1201         }
1202         return nr - (cache_end - cache);
1203 }
1204
1205 static int clear_ce_flags(struct cache_entry **cache, int nr,
1206                             int select_mask, int clear_mask,
1207                             struct exclude_list *el)
1208 {
1209         static struct strbuf prefix = STRBUF_INIT;
1210
1211         strbuf_reset(&prefix);
1212
1213         return clear_ce_flags_1(cache, nr,
1214                                 &prefix,
1215                                 select_mask, clear_mask,
1216                                 el, 0);
1217 }
1218
1219 /*
1220  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1221  */
1222 static void mark_new_skip_worktree(struct exclude_list *el,
1223                                    struct index_state *the_index,
1224                                    int select_flag, int skip_wt_flag)
1225 {
1226         int i;
1227
1228         /*
1229          * 1. Pretend the narrowest worktree: only unmerged entries
1230          * are checked out
1231          */
1232         for (i = 0; i < the_index->cache_nr; i++) {
1233                 struct cache_entry *ce = the_index->cache[i];
1234
1235                 if (select_flag && !(ce->ce_flags & select_flag))
1236                         continue;
1237
1238                 if (!ce_stage(ce))
1239                         ce->ce_flags |= skip_wt_flag;
1240                 else
1241                         ce->ce_flags &= ~skip_wt_flag;
1242         }
1243
1244         /*
1245          * 2. Widen worktree according to sparse-checkout file.
1246          * Matched entries will have skip_wt_flag cleared (i.e. "in")
1247          */
1248         clear_ce_flags(the_index->cache, the_index->cache_nr,
1249                        select_flag, skip_wt_flag, el);
1250 }
1251
1252 static int verify_absent(const struct cache_entry *,
1253                          enum unpack_trees_error_types,
1254                          struct unpack_trees_options *);
1255 /*
1256  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1257  * resulting index, -2 on failure to reflect the changes to the work tree.
1258  *
1259  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1260  */
1261 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1262 {
1263         int i, ret;
1264         static struct cache_entry *dfc;
1265         struct exclude_list el;
1266
1267         if (len > MAX_UNPACK_TREES)
1268                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1269
1270         memset(&el, 0, sizeof(el));
1271         if (!core_apply_sparse_checkout || !o->update)
1272                 o->skip_sparse_checkout = 1;
1273         if (!o->skip_sparse_checkout) {
1274                 char *sparse = git_pathdup("info/sparse-checkout");
1275                 if (add_excludes_from_file_to_list(sparse, "", 0, &el, NULL) < 0)
1276                         o->skip_sparse_checkout = 1;
1277                 else
1278                         o->el = &el;
1279                 free(sparse);
1280         }
1281
1282         memset(&o->result, 0, sizeof(o->result));
1283         o->result.initialized = 1;
1284         o->result.timestamp.sec = o->src_index->timestamp.sec;
1285         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1286         o->result.version = o->src_index->version;
1287         o->result.split_index = o->src_index->split_index;
1288         if (o->result.split_index)
1289                 o->result.split_index->refcount++;
1290         hashcpy(o->result.sha1, o->src_index->sha1);
1291         o->merge_size = len;
1292         mark_all_ce_unused(o->src_index);
1293
1294         /*
1295          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1296          */
1297         if (!o->skip_sparse_checkout)
1298                 mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1299
1300         if (!dfc)
1301                 dfc = xcalloc(1, cache_entry_size(0));
1302         o->df_conflict_entry = dfc;
1303
1304         if (len) {
1305                 const char *prefix = o->prefix ? o->prefix : "";
1306                 struct traverse_info info;
1307
1308                 setup_traverse_info(&info, prefix);
1309                 info.fn = unpack_callback;
1310                 info.data = o;
1311                 info.show_all_errors = o->show_all_errors;
1312                 info.pathspec = o->pathspec;
1313
1314                 if (o->prefix) {
1315                         /*
1316                          * Unpack existing index entries that sort before the
1317                          * prefix the tree is spliced into.  Note that o->merge
1318                          * is always true in this case.
1319                          */
1320                         while (1) {
1321                                 struct cache_entry *ce = next_cache_entry(o);
1322                                 if (!ce)
1323                                         break;
1324                                 if (ce_in_traverse_path(ce, &info))
1325                                         break;
1326                                 if (unpack_index_entry(ce, o) < 0)
1327                                         goto return_failed;
1328                         }
1329                 }
1330
1331                 if (traverse_trees(len, t, &info) < 0)
1332                         goto return_failed;
1333         }
1334
1335         /* Any left-over entries in the index? */
1336         if (o->merge) {
1337                 while (1) {
1338                         struct cache_entry *ce = next_cache_entry(o);
1339                         if (!ce)
1340                                 break;
1341                         if (unpack_index_entry(ce, o) < 0)
1342                                 goto return_failed;
1343                 }
1344         }
1345         mark_all_ce_unused(o->src_index);
1346
1347         if (o->trivial_merges_only && o->nontrivial_merge) {
1348                 ret = unpack_failed(o, "Merge requires file-level merging");
1349                 goto done;
1350         }
1351
1352         if (!o->skip_sparse_checkout) {
1353                 int empty_worktree = 1;
1354
1355                 /*
1356                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1357                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1358                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1359                  */
1360                 mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1361
1362                 ret = 0;
1363                 for (i = 0; i < o->result.cache_nr; i++) {
1364                         struct cache_entry *ce = o->result.cache[i];
1365
1366                         /*
1367                          * Entries marked with CE_ADDED in merged_entry() do not have
1368                          * verify_absent() check (the check is effectively disabled
1369                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1370                          *
1371                          * Do the real check now because we have had
1372                          * correct CE_NEW_SKIP_WORKTREE
1373                          */
1374                         if (ce->ce_flags & CE_ADDED &&
1375                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1376                                 if (!o->show_all_errors)
1377                                         goto return_failed;
1378                                 ret = -1;
1379                         }
1380
1381                         if (apply_sparse_checkout(&o->result, ce, o)) {
1382                                 if (!o->show_all_errors)
1383                                         goto return_failed;
1384                                 ret = -1;
1385                         }
1386                         if (!ce_skip_worktree(ce))
1387                                 empty_worktree = 0;
1388
1389                 }
1390                 if (ret < 0)
1391                         goto return_failed;
1392                 /*
1393                  * Sparse checkout is meant to narrow down checkout area
1394                  * but it does not make sense to narrow down to empty working
1395                  * tree. This is usually a mistake in sparse checkout rules.
1396                  * Do not allow users to do that.
1397                  */
1398                 if (o->result.cache_nr && empty_worktree) {
1399                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1400                         goto done;
1401                 }
1402         }
1403
1404         o->src_index = NULL;
1405         ret = check_updates(o) ? (-2) : 0;
1406         if (o->dst_index) {
1407                 if (!ret) {
1408                         if (!o->result.cache_tree)
1409                                 o->result.cache_tree = cache_tree();
1410                         if (!cache_tree_fully_valid(o->result.cache_tree))
1411                                 cache_tree_update(&o->result,
1412                                                   WRITE_TREE_SILENT |
1413                                                   WRITE_TREE_REPAIR);
1414                 }
1415                 move_index_extensions(&o->result, o->dst_index);
1416                 discard_index(o->dst_index);
1417                 *o->dst_index = o->result;
1418         } else {
1419                 discard_index(&o->result);
1420         }
1421
1422 done:
1423         clear_exclude_list(&el);
1424         return ret;
1425
1426 return_failed:
1427         if (o->show_all_errors)
1428                 display_error_msgs(o);
1429         mark_all_ce_unused(o->src_index);
1430         ret = unpack_failed(o, NULL);
1431         if (o->exiting_early)
1432                 ret = 0;
1433         goto done;
1434 }
1435
1436 /* Here come the merge functions */
1437
1438 static int reject_merge(const struct cache_entry *ce,
1439                         struct unpack_trees_options *o)
1440 {
1441         return o->gently ? -1 :
1442                 add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1443 }
1444
1445 static int same(const struct cache_entry *a, const struct cache_entry *b)
1446 {
1447         if (!!a != !!b)
1448                 return 0;
1449         if (!a && !b)
1450                 return 1;
1451         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1452                 return 0;
1453         return a->ce_mode == b->ce_mode &&
1454                !oidcmp(&a->oid, &b->oid);
1455 }
1456
1457
1458 /*
1459  * When a CE gets turned into an unmerged entry, we
1460  * want it to be up-to-date
1461  */
1462 static int verify_uptodate_1(const struct cache_entry *ce,
1463                              struct unpack_trees_options *o,
1464                              enum unpack_trees_error_types error_type)
1465 {
1466         struct stat st;
1467
1468         if (o->index_only)
1469                 return 0;
1470
1471         /*
1472          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1473          * if this entry is truly up-to-date because this file may be
1474          * overwritten.
1475          */
1476         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1477                 ; /* keep checking */
1478         else if (o->reset || ce_uptodate(ce))
1479                 return 0;
1480
1481         if (!lstat(ce->name, &st)) {
1482                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1483                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1484
1485                 if (submodule_from_ce(ce)) {
1486                         int r = check_submodule_move_head(ce,
1487                                 "HEAD", oid_to_hex(&ce->oid), o);
1488                         if (r)
1489                                 return o->gently ? -1 :
1490                                         add_rejected_path(o, error_type, ce->name);
1491                         return 0;
1492                 }
1493
1494                 if (!changed)
1495                         return 0;
1496                 /*
1497                  * Historic default policy was to allow submodule to be out
1498                  * of sync wrt the superproject index. If the submodule was
1499                  * not considered interesting above, we don't care here.
1500                  */
1501                 if (S_ISGITLINK(ce->ce_mode))
1502                         return 0;
1503
1504                 errno = 0;
1505         }
1506         if (errno == ENOENT)
1507                 return 0;
1508         return o->gently ? -1 :
1509                 add_rejected_path(o, error_type, ce->name);
1510 }
1511
1512 int verify_uptodate(const struct cache_entry *ce,
1513                     struct unpack_trees_options *o)
1514 {
1515         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1516                 return 0;
1517         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1518 }
1519
1520 static int verify_uptodate_sparse(const struct cache_entry *ce,
1521                                   struct unpack_trees_options *o)
1522 {
1523         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1524 }
1525
1526 static void invalidate_ce_path(const struct cache_entry *ce,
1527                                struct unpack_trees_options *o)
1528 {
1529         if (!ce)
1530                 return;
1531         cache_tree_invalidate_path(o->src_index, ce->name);
1532         untracked_cache_invalidate_path(o->src_index, ce->name, 1);
1533 }
1534
1535 /*
1536  * Check that checking out ce->sha1 in subdir ce->name is not
1537  * going to overwrite any working files.
1538  *
1539  * Currently, git does not checkout subprojects during a superproject
1540  * checkout, so it is not going to overwrite anything.
1541  */
1542 static int verify_clean_submodule(const char *old_sha1,
1543                                   const struct cache_entry *ce,
1544                                   enum unpack_trees_error_types error_type,
1545                                   struct unpack_trees_options *o)
1546 {
1547         if (!submodule_from_ce(ce))
1548                 return 0;
1549
1550         return check_submodule_move_head(ce, old_sha1,
1551                                          oid_to_hex(&ce->oid), o);
1552 }
1553
1554 static int verify_clean_subdirectory(const struct cache_entry *ce,
1555                                      enum unpack_trees_error_types error_type,
1556                                      struct unpack_trees_options *o)
1557 {
1558         /*
1559          * we are about to extract "ce->name"; we would not want to lose
1560          * anything in the existing directory there.
1561          */
1562         int namelen;
1563         int i;
1564         struct dir_struct d;
1565         char *pathbuf;
1566         int cnt = 0;
1567
1568         if (S_ISGITLINK(ce->ce_mode)) {
1569                 struct object_id oid;
1570                 int sub_head = resolve_gitlink_ref(ce->name, "HEAD", &oid);
1571                 /*
1572                  * If we are not going to update the submodule, then
1573                  * we don't care.
1574                  */
1575                 if (!sub_head && !oidcmp(&oid, &ce->oid))
1576                         return 0;
1577                 return verify_clean_submodule(sub_head ? NULL : oid_to_hex(&oid),
1578                                               ce, error_type, o);
1579         }
1580
1581         /*
1582          * First let's make sure we do not have a local modification
1583          * in that directory.
1584          */
1585         namelen = ce_namelen(ce);
1586         for (i = locate_in_src_index(ce, o);
1587              i < o->src_index->cache_nr;
1588              i++) {
1589                 struct cache_entry *ce2 = o->src_index->cache[i];
1590                 int len = ce_namelen(ce2);
1591                 if (len < namelen ||
1592                     strncmp(ce->name, ce2->name, namelen) ||
1593                     ce2->name[namelen] != '/')
1594                         break;
1595                 /*
1596                  * ce2->name is an entry in the subdirectory to be
1597                  * removed.
1598                  */
1599                 if (!ce_stage(ce2)) {
1600                         if (verify_uptodate(ce2, o))
1601                                 return -1;
1602                         add_entry(o, ce2, CE_REMOVE, 0);
1603                         mark_ce_used(ce2, o);
1604                 }
1605                 cnt++;
1606         }
1607
1608         /*
1609          * Then we need to make sure that we do not lose a locally
1610          * present file that is not ignored.
1611          */
1612         pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1613
1614         memset(&d, 0, sizeof(d));
1615         if (o->dir)
1616                 d.exclude_per_dir = o->dir->exclude_per_dir;
1617         i = read_directory(&d, &the_index, pathbuf, namelen+1, NULL);
1618         if (i)
1619                 return o->gently ? -1 :
1620                         add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1621         free(pathbuf);
1622         return cnt;
1623 }
1624
1625 /*
1626  * This gets called when there was no index entry for the tree entry 'dst',
1627  * but we found a file in the working tree that 'lstat()' said was fine,
1628  * and we're on a case-insensitive filesystem.
1629  *
1630  * See if we can find a case-insensitive match in the index that also
1631  * matches the stat information, and assume it's that other file!
1632  */
1633 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1634 {
1635         const struct cache_entry *src;
1636
1637         src = index_file_exists(o->src_index, name, len, 1);
1638         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1639 }
1640
1641 static int check_ok_to_remove(const char *name, int len, int dtype,
1642                               const struct cache_entry *ce, struct stat *st,
1643                               enum unpack_trees_error_types error_type,
1644                               struct unpack_trees_options *o)
1645 {
1646         const struct cache_entry *result;
1647
1648         /*
1649          * It may be that the 'lstat()' succeeded even though
1650          * target 'ce' was absent, because there is an old
1651          * entry that is different only in case..
1652          *
1653          * Ignore that lstat() if it matches.
1654          */
1655         if (ignore_case && icase_exists(o, name, len, st))
1656                 return 0;
1657
1658         if (o->dir &&
1659             is_excluded(o->dir, &the_index, name, &dtype))
1660                 /*
1661                  * ce->name is explicitly excluded, so it is Ok to
1662                  * overwrite it.
1663                  */
1664                 return 0;
1665         if (S_ISDIR(st->st_mode)) {
1666                 /*
1667                  * We are checking out path "foo" and
1668                  * found "foo/." in the working tree.
1669                  * This is tricky -- if we have modified
1670                  * files that are in "foo/" we would lose
1671                  * them.
1672                  */
1673                 if (verify_clean_subdirectory(ce, error_type, o) < 0)
1674                         return -1;
1675                 return 0;
1676         }
1677
1678         /*
1679          * The previous round may already have decided to
1680          * delete this path, which is in a subdirectory that
1681          * is being replaced with a blob.
1682          */
1683         result = index_file_exists(&o->result, name, len, 0);
1684         if (result) {
1685                 if (result->ce_flags & CE_REMOVE)
1686                         return 0;
1687         }
1688
1689         return o->gently ? -1 :
1690                 add_rejected_path(o, error_type, name);
1691 }
1692
1693 /*
1694  * We do not want to remove or overwrite a working tree file that
1695  * is not tracked, unless it is ignored.
1696  */
1697 static int verify_absent_1(const struct cache_entry *ce,
1698                            enum unpack_trees_error_types error_type,
1699                            struct unpack_trees_options *o)
1700 {
1701         int len;
1702         struct stat st;
1703
1704         if (o->index_only || o->reset || !o->update)
1705                 return 0;
1706
1707         len = check_leading_path(ce->name, ce_namelen(ce));
1708         if (!len)
1709                 return 0;
1710         else if (len > 0) {
1711                 char *path;
1712                 int ret;
1713
1714                 path = xmemdupz(ce->name, len);
1715                 if (lstat(path, &st))
1716                         ret = error_errno("cannot stat '%s'", path);
1717                 else {
1718                         if (submodule_from_ce(ce))
1719                                 ret = check_submodule_move_head(ce,
1720                                                                 oid_to_hex(&ce->oid),
1721                                                                 NULL, o);
1722                         else
1723                                 ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
1724                                                          &st, error_type, o);
1725                 }
1726                 free(path);
1727                 return ret;
1728         } else if (lstat(ce->name, &st)) {
1729                 if (errno != ENOENT)
1730                         return error_errno("cannot stat '%s'", ce->name);
1731                 return 0;
1732         } else {
1733                 if (submodule_from_ce(ce))
1734                         return check_submodule_move_head(ce, oid_to_hex(&ce->oid),
1735                                                          NULL, o);
1736
1737                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1738                                           ce_to_dtype(ce), ce, &st,
1739                                           error_type, o);
1740         }
1741 }
1742
1743 static int verify_absent(const struct cache_entry *ce,
1744                          enum unpack_trees_error_types error_type,
1745                          struct unpack_trees_options *o)
1746 {
1747         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1748                 return 0;
1749         return verify_absent_1(ce, error_type, o);
1750 }
1751
1752 static int verify_absent_sparse(const struct cache_entry *ce,
1753                                 enum unpack_trees_error_types error_type,
1754                                 struct unpack_trees_options *o)
1755 {
1756         enum unpack_trees_error_types orphaned_error = error_type;
1757         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1758                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1759
1760         return verify_absent_1(ce, orphaned_error, o);
1761 }
1762
1763 static int merged_entry(const struct cache_entry *ce,
1764                         const struct cache_entry *old,
1765                         struct unpack_trees_options *o)
1766 {
1767         int update = CE_UPDATE;
1768         struct cache_entry *merge = dup_entry(ce);
1769
1770         if (!old) {
1771                 /*
1772                  * New index entries. In sparse checkout, the following
1773                  * verify_absent() will be delayed until after
1774                  * traverse_trees() finishes in unpack_trees(), then:
1775                  *
1776                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1777                  *  - verify_absent() be called again, this time with
1778                  *    correct CE_NEW_SKIP_WORKTREE
1779                  *
1780                  * verify_absent() call here does nothing in sparse
1781                  * checkout (i.e. o->skip_sparse_checkout == 0)
1782                  */
1783                 update |= CE_ADDED;
1784                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1785
1786                 if (verify_absent(merge,
1787                                   ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1788                         free(merge);
1789                         return -1;
1790                 }
1791                 invalidate_ce_path(merge, o);
1792
1793                 if (submodule_from_ce(ce)) {
1794                         int ret = check_submodule_move_head(ce, NULL,
1795                                                             oid_to_hex(&ce->oid),
1796                                                             o);
1797                         if (ret)
1798                                 return ret;
1799                 }
1800
1801         } else if (!(old->ce_flags & CE_CONFLICTED)) {
1802                 /*
1803                  * See if we can re-use the old CE directly?
1804                  * That way we get the uptodate stat info.
1805                  *
1806                  * This also removes the UPDATE flag on a match; otherwise
1807                  * we will end up overwriting local changes in the work tree.
1808                  */
1809                 if (same(old, merge)) {
1810                         copy_cache_entry(merge, old);
1811                         update = 0;
1812                 } else {
1813                         if (verify_uptodate(old, o)) {
1814                                 free(merge);
1815                                 return -1;
1816                         }
1817                         /* Migrate old flags over */
1818                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1819                         invalidate_ce_path(old, o);
1820                 }
1821
1822                 if (submodule_from_ce(ce)) {
1823                         int ret = check_submodule_move_head(ce, oid_to_hex(&old->oid),
1824                                                             oid_to_hex(&ce->oid),
1825                                                             o);
1826                         if (ret)
1827                                 return ret;
1828                 }
1829         } else {
1830                 /*
1831                  * Previously unmerged entry left as an existence
1832                  * marker by read_index_unmerged();
1833                  */
1834                 invalidate_ce_path(old, o);
1835         }
1836
1837         do_add_entry(o, merge, update, CE_STAGEMASK);
1838         return 1;
1839 }
1840
1841 static int deleted_entry(const struct cache_entry *ce,
1842                          const struct cache_entry *old,
1843                          struct unpack_trees_options *o)
1844 {
1845         /* Did it exist in the index? */
1846         if (!old) {
1847                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1848                         return -1;
1849                 return 0;
1850         }
1851         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1852                 return -1;
1853         add_entry(o, ce, CE_REMOVE, 0);
1854         invalidate_ce_path(ce, o);
1855         return 1;
1856 }
1857
1858 static int keep_entry(const struct cache_entry *ce,
1859                       struct unpack_trees_options *o)
1860 {
1861         add_entry(o, ce, 0, 0);
1862         return 1;
1863 }
1864
1865 #if DBRT_DEBUG
1866 static void show_stage_entry(FILE *o,
1867                              const char *label, const struct cache_entry *ce)
1868 {
1869         if (!ce)
1870                 fprintf(o, "%s (missing)\n", label);
1871         else
1872                 fprintf(o, "%s%06o %s %d\t%s\n",
1873                         label,
1874                         ce->ce_mode,
1875                         oid_to_hex(&ce->oid),
1876                         ce_stage(ce),
1877                         ce->name);
1878 }
1879 #endif
1880
1881 int threeway_merge(const struct cache_entry * const *stages,
1882                    struct unpack_trees_options *o)
1883 {
1884         const struct cache_entry *index;
1885         const struct cache_entry *head;
1886         const struct cache_entry *remote = stages[o->head_idx + 1];
1887         int count;
1888         int head_match = 0;
1889         int remote_match = 0;
1890
1891         int df_conflict_head = 0;
1892         int df_conflict_remote = 0;
1893
1894         int any_anc_missing = 0;
1895         int no_anc_exists = 1;
1896         int i;
1897
1898         for (i = 1; i < o->head_idx; i++) {
1899                 if (!stages[i] || stages[i] == o->df_conflict_entry)
1900                         any_anc_missing = 1;
1901                 else
1902                         no_anc_exists = 0;
1903         }
1904
1905         index = stages[0];
1906         head = stages[o->head_idx];
1907
1908         if (head == o->df_conflict_entry) {
1909                 df_conflict_head = 1;
1910                 head = NULL;
1911         }
1912
1913         if (remote == o->df_conflict_entry) {
1914                 df_conflict_remote = 1;
1915                 remote = NULL;
1916         }
1917
1918         /*
1919          * First, if there's a #16 situation, note that to prevent #13
1920          * and #14.
1921          */
1922         if (!same(remote, head)) {
1923                 for (i = 1; i < o->head_idx; i++) {
1924                         if (same(stages[i], head)) {
1925                                 head_match = i;
1926                         }
1927                         if (same(stages[i], remote)) {
1928                                 remote_match = i;
1929                         }
1930                 }
1931         }
1932
1933         /*
1934          * We start with cases where the index is allowed to match
1935          * something other than the head: #14(ALT) and #2ALT, where it
1936          * is permitted to match the result instead.
1937          */
1938         /* #14, #14ALT, #2ALT */
1939         if (remote && !df_conflict_head && head_match && !remote_match) {
1940                 if (index && !same(index, remote) && !same(index, head))
1941                         return reject_merge(index, o);
1942                 return merged_entry(remote, index, o);
1943         }
1944         /*
1945          * If we have an entry in the index cache, then we want to
1946          * make sure that it matches head.
1947          */
1948         if (index && !same(index, head))
1949                 return reject_merge(index, o);
1950
1951         if (head) {
1952                 /* #5ALT, #15 */
1953                 if (same(head, remote))
1954                         return merged_entry(head, index, o);
1955                 /* #13, #3ALT */
1956                 if (!df_conflict_remote && remote_match && !head_match)
1957                         return merged_entry(head, index, o);
1958         }
1959
1960         /* #1 */
1961         if (!head && !remote && any_anc_missing)
1962                 return 0;
1963
1964         /*
1965          * Under the "aggressive" rule, we resolve mostly trivial
1966          * cases that we historically had git-merge-one-file resolve.
1967          */
1968         if (o->aggressive) {
1969                 int head_deleted = !head;
1970                 int remote_deleted = !remote;
1971                 const struct cache_entry *ce = NULL;
1972
1973                 if (index)
1974                         ce = index;
1975                 else if (head)
1976                         ce = head;
1977                 else if (remote)
1978                         ce = remote;
1979                 else {
1980                         for (i = 1; i < o->head_idx; i++) {
1981                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
1982                                         ce = stages[i];
1983                                         break;
1984                                 }
1985                         }
1986                 }
1987
1988                 /*
1989                  * Deleted in both.
1990                  * Deleted in one and unchanged in the other.
1991                  */
1992                 if ((head_deleted && remote_deleted) ||
1993                     (head_deleted && remote && remote_match) ||
1994                     (remote_deleted && head && head_match)) {
1995                         if (index)
1996                                 return deleted_entry(index, index, o);
1997                         if (ce && !head_deleted) {
1998                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1999                                         return -1;
2000                         }
2001                         return 0;
2002                 }
2003                 /*
2004                  * Added in both, identically.
2005                  */
2006                 if (no_anc_exists && head && remote && same(head, remote))
2007                         return merged_entry(head, index, o);
2008
2009         }
2010
2011         /* Below are "no merge" cases, which require that the index be
2012          * up-to-date to avoid the files getting overwritten with
2013          * conflict resolution files.
2014          */
2015         if (index) {
2016                 if (verify_uptodate(index, o))
2017                         return -1;
2018         }
2019
2020         o->nontrivial_merge = 1;
2021
2022         /* #2, #3, #4, #6, #7, #9, #10, #11. */
2023         count = 0;
2024         if (!head_match || !remote_match) {
2025                 for (i = 1; i < o->head_idx; i++) {
2026                         if (stages[i] && stages[i] != o->df_conflict_entry) {
2027                                 keep_entry(stages[i], o);
2028                                 count++;
2029                                 break;
2030                         }
2031                 }
2032         }
2033 #if DBRT_DEBUG
2034         else {
2035                 fprintf(stderr, "read-tree: warning #16 detected\n");
2036                 show_stage_entry(stderr, "head   ", stages[head_match]);
2037                 show_stage_entry(stderr, "remote ", stages[remote_match]);
2038         }
2039 #endif
2040         if (head) { count += keep_entry(head, o); }
2041         if (remote) { count += keep_entry(remote, o); }
2042         return count;
2043 }
2044
2045 /*
2046  * Two-way merge.
2047  *
2048  * The rule is to "carry forward" what is in the index without losing
2049  * information across a "fast-forward", favoring a successful merge
2050  * over a merge failure when it makes sense.  For details of the
2051  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
2052  *
2053  */
2054 int twoway_merge(const struct cache_entry * const *src,
2055                  struct unpack_trees_options *o)
2056 {
2057         const struct cache_entry *current = src[0];
2058         const struct cache_entry *oldtree = src[1];
2059         const struct cache_entry *newtree = src[2];
2060
2061         if (o->merge_size != 2)
2062                 return error("Cannot do a twoway merge of %d trees",
2063                              o->merge_size);
2064
2065         if (oldtree == o->df_conflict_entry)
2066                 oldtree = NULL;
2067         if (newtree == o->df_conflict_entry)
2068                 newtree = NULL;
2069
2070         if (current) {
2071                 if (current->ce_flags & CE_CONFLICTED) {
2072                         if (same(oldtree, newtree) || o->reset) {
2073                                 if (!newtree)
2074                                         return deleted_entry(current, current, o);
2075                                 else
2076                                         return merged_entry(newtree, current, o);
2077                         }
2078                         return reject_merge(current, o);
2079                 } else if ((!oldtree && !newtree) || /* 4 and 5 */
2080                          (!oldtree && newtree &&
2081                           same(current, newtree)) || /* 6 and 7 */
2082                          (oldtree && newtree &&
2083                           same(oldtree, newtree)) || /* 14 and 15 */
2084                          (oldtree && newtree &&
2085                           !same(oldtree, newtree) && /* 18 and 19 */
2086                           same(current, newtree))) {
2087                         return keep_entry(current, o);
2088                 } else if (oldtree && !newtree && same(current, oldtree)) {
2089                         /* 10 or 11 */
2090                         return deleted_entry(oldtree, current, o);
2091                 } else if (oldtree && newtree &&
2092                          same(current, oldtree) && !same(current, newtree)) {
2093                         /* 20 or 21 */
2094                         return merged_entry(newtree, current, o);
2095                 } else
2096                         return reject_merge(current, o);
2097         }
2098         else if (newtree) {
2099                 if (oldtree && !o->initial_checkout) {
2100                         /*
2101                          * deletion of the path was staged;
2102                          */
2103                         if (same(oldtree, newtree))
2104                                 return 1;
2105                         return reject_merge(oldtree, o);
2106                 }
2107                 return merged_entry(newtree, current, o);
2108         }
2109         return deleted_entry(oldtree, current, o);
2110 }
2111
2112 /*
2113  * Bind merge.
2114  *
2115  * Keep the index entries at stage0, collapse stage1 but make sure
2116  * stage0 does not have anything there.
2117  */
2118 int bind_merge(const struct cache_entry * const *src,
2119                struct unpack_trees_options *o)
2120 {
2121         const struct cache_entry *old = src[0];
2122         const struct cache_entry *a = src[1];
2123
2124         if (o->merge_size != 1)
2125                 return error("Cannot do a bind merge of %d trees",
2126                              o->merge_size);
2127         if (a && old)
2128                 return o->gently ? -1 :
2129                         error(ERRORMSG(o, ERROR_BIND_OVERLAP),
2130                               super_prefixed(a->name),
2131                               super_prefixed(old->name));
2132         if (!a)
2133                 return keep_entry(old, o);
2134         else
2135                 return merged_entry(a, NULL, o);
2136 }
2137
2138 /*
2139  * One-way merge.
2140  *
2141  * The rule is:
2142  * - take the stat information from stage0, take the data from stage1
2143  */
2144 int oneway_merge(const struct cache_entry * const *src,
2145                  struct unpack_trees_options *o)
2146 {
2147         const struct cache_entry *old = src[0];
2148         const struct cache_entry *a = src[1];
2149
2150         if (o->merge_size != 1)
2151                 return error("Cannot do a oneway merge of %d trees",
2152                              o->merge_size);
2153
2154         if (!a || a == o->df_conflict_entry)
2155                 return deleted_entry(old, old, o);
2156
2157         if (old && same(old, a)) {
2158                 int update = 0;
2159                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
2160                         struct stat st;
2161                         if (lstat(old->name, &st) ||
2162                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
2163                                 update |= CE_UPDATE;
2164                 }
2165                 if (o->update && S_ISGITLINK(old->ce_mode) &&
2166                     should_update_submodules() && !verify_uptodate(old, o))
2167                         update |= CE_UPDATE;
2168                 add_entry(o, old, update, 0);
2169                 return 0;
2170         }
2171         return merged_entry(a, old, o);
2172 }