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