pkt-line: introduce struct packet_writer
[git] / unpack-trees.c
1 #define NO_THE_INDEX_COMPATIBILITY_MACROS
2 #include "cache.h"
3 #include "argv-array.h"
4 #include "repository.h"
5 #include "config.h"
6 #include "dir.h"
7 #include "tree.h"
8 #include "tree-walk.h"
9 #include "cache-tree.h"
10 #include "unpack-trees.h"
11 #include "progress.h"
12 #include "refs.h"
13 #include "attr.h"
14 #include "split-index.h"
15 #include "dir.h"
16 #include "submodule.h"
17 #include "submodule-config.h"
18 #include "fsmonitor.h"
19 #include "object-store.h"
20 #include "fetch-object.h"
21
22 /*
23  * Error messages expected by scripts out of plumbing commands such as
24  * read-tree.  Non-scripted Porcelain is not required to use these messages
25  * and in fact are encouraged to reword them to better suit their particular
26  * situation better.  See how "git checkout" and "git merge" replaces
27  * them using setup_unpack_trees_porcelain(), for example.
28  */
29 static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
30         /* ERROR_WOULD_OVERWRITE */
31         "Entry '%s' would be overwritten by merge. Cannot merge.",
32
33         /* ERROR_NOT_UPTODATE_FILE */
34         "Entry '%s' not uptodate. Cannot merge.",
35
36         /* ERROR_NOT_UPTODATE_DIR */
37         "Updating '%s' would lose untracked files in it",
38
39         /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
40         "Untracked working tree file '%s' would be overwritten by merge.",
41
42         /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
43         "Untracked working tree file '%s' would be removed by merge.",
44
45         /* ERROR_BIND_OVERLAP */
46         "Entry '%s' overlaps with '%s'.  Cannot bind.",
47
48         /* ERROR_SPARSE_NOT_UPTODATE_FILE */
49         "Entry '%s' not uptodate. Cannot update sparse checkout.",
50
51         /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
52         "Working tree file '%s' would be overwritten by sparse checkout update.",
53
54         /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
55         "Working tree file '%s' would be removed by sparse checkout update.",
56
57         /* ERROR_WOULD_LOSE_SUBMODULE */
58         "Submodule '%s' cannot checkout new HEAD.",
59 };
60
61 #define ERRORMSG(o,type) \
62         ( ((o) && (o)->msgs[(type)]) \
63           ? ((o)->msgs[(type)])      \
64           : (unpack_plumbing_errors[(type)]) )
65
66 static const char *super_prefixed(const char *path)
67 {
68         /*
69          * It is necessary and sufficient to have two static buffers
70          * here, as the return value of this function is fed to
71          * error() using the unpack_*_errors[] templates we see above.
72          */
73         static struct strbuf buf[2] = {STRBUF_INIT, STRBUF_INIT};
74         static int super_prefix_len = -1;
75         static unsigned idx = ARRAY_SIZE(buf) - 1;
76
77         if (super_prefix_len < 0) {
78                 const char *super_prefix = get_super_prefix();
79                 if (!super_prefix) {
80                         super_prefix_len = 0;
81                 } else {
82                         int i;
83                         for (i = 0; i < ARRAY_SIZE(buf); i++)
84                                 strbuf_addstr(&buf[i], super_prefix);
85                         super_prefix_len = buf[0].len;
86                 }
87         }
88
89         if (!super_prefix_len)
90                 return path;
91
92         if (++idx >= ARRAY_SIZE(buf))
93                 idx = 0;
94
95         strbuf_setlen(&buf[idx], super_prefix_len);
96         strbuf_addstr(&buf[idx], path);
97
98         return buf[idx].buf;
99 }
100
101 void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
102                                   const char *cmd)
103 {
104         int i;
105         const char **msgs = opts->msgs;
106         const char *msg;
107
108         argv_array_init(&opts->msgs_to_free);
109
110         if (!strcmp(cmd, "checkout"))
111                 msg = advice_commit_before_merge
112                       ? _("Your local changes to the following files would be overwritten by checkout:\n%%s"
113                           "Please commit your changes or stash them before you switch branches.")
114                       : _("Your local changes to the following files would be overwritten by checkout:\n%%s");
115         else if (!strcmp(cmd, "merge"))
116                 msg = advice_commit_before_merge
117                       ? _("Your local changes to the following files would be overwritten by merge:\n%%s"
118                           "Please commit your changes or stash them before you merge.")
119                       : _("Your local changes to the following files would be overwritten by merge:\n%%s");
120         else
121                 msg = advice_commit_before_merge
122                       ? _("Your local changes to the following files would be overwritten by %s:\n%%s"
123                           "Please commit your changes or stash them before you %s.")
124                       : _("Your local changes to the following files would be overwritten by %s:\n%%s");
125         msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
126                 argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
127
128         msgs[ERROR_NOT_UPTODATE_DIR] =
129                 _("Updating the following directories would lose untracked files in them:\n%s");
130
131         if (!strcmp(cmd, "checkout"))
132                 msg = advice_commit_before_merge
133                       ? _("The following untracked working tree files would be removed by checkout:\n%%s"
134                           "Please move or remove them before you switch branches.")
135                       : _("The following untracked working tree files would be removed by checkout:\n%%s");
136         else if (!strcmp(cmd, "merge"))
137                 msg = advice_commit_before_merge
138                       ? _("The following untracked working tree files would be removed by merge:\n%%s"
139                           "Please move or remove them before you merge.")
140                       : _("The following untracked working tree files would be removed by merge:\n%%s");
141         else
142                 msg = advice_commit_before_merge
143                       ? _("The following untracked working tree files would be removed by %s:\n%%s"
144                           "Please move or remove them before you %s.")
145                       : _("The following untracked working tree files would be removed by %s:\n%%s");
146         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] =
147                 argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
148
149         if (!strcmp(cmd, "checkout"))
150                 msg = advice_commit_before_merge
151                       ? _("The following untracked working tree files would be overwritten by checkout:\n%%s"
152                           "Please move or remove them before you switch branches.")
153                       : _("The following untracked working tree files would be overwritten by checkout:\n%%s");
154         else if (!strcmp(cmd, "merge"))
155                 msg = advice_commit_before_merge
156                       ? _("The following untracked working tree files would be overwritten by merge:\n%%s"
157                           "Please move or remove them before you merge.")
158                       : _("The following untracked working tree files would be overwritten by merge:\n%%s");
159         else
160                 msg = advice_commit_before_merge
161                       ? _("The following untracked working tree files would be overwritten by %s:\n%%s"
162                           "Please move or remove them before you %s.")
163                       : _("The following untracked working tree files would be overwritten by %s:\n%%s");
164         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] =
165                 argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
166
167         /*
168          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
169          * cannot easily display it as a list.
170          */
171         msgs[ERROR_BIND_OVERLAP] = _("Entry '%s' overlaps with '%s'.  Cannot bind.");
172
173         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
174                 _("Cannot update sparse checkout: the following entries are not up to date:\n%s");
175         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
176                 _("The following working tree files would be overwritten by sparse checkout update:\n%s");
177         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
178                 _("The following working tree files would be removed by sparse checkout update:\n%s");
179         msgs[ERROR_WOULD_LOSE_SUBMODULE] =
180                 _("Cannot update submodule:\n%s");
181
182         opts->show_all_errors = 1;
183         /* rejected paths may not have a static buffer */
184         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
185                 opts->unpack_rejects[i].strdup_strings = 1;
186 }
187
188 void clear_unpack_trees_porcelain(struct unpack_trees_options *opts)
189 {
190         argv_array_clear(&opts->msgs_to_free);
191         memset(opts->msgs, 0, sizeof(opts->msgs));
192 }
193
194 static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
195                          unsigned int set, unsigned int clear)
196 {
197         clear |= CE_HASHED;
198
199         if (set & CE_REMOVE)
200                 set |= CE_WT_REMOVE;
201
202         ce->ce_flags = (ce->ce_flags & ~clear) | set;
203         return add_index_entry(&o->result, ce,
204                                ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
205 }
206
207 static void add_entry(struct unpack_trees_options *o,
208                       const struct cache_entry *ce,
209                       unsigned int set, unsigned int clear)
210 {
211         do_add_entry(o, dup_cache_entry(ce, &o->result), set, clear);
212 }
213
214 /*
215  * add error messages on path <path>
216  * corresponding to the type <e> with the message <msg>
217  * indicating if it should be display in porcelain or not
218  */
219 static int add_rejected_path(struct unpack_trees_options *o,
220                              enum unpack_trees_error_types e,
221                              const char *path)
222 {
223         if (!o->show_all_errors)
224                 return error(ERRORMSG(o, e), super_prefixed(path));
225
226         /*
227          * Otherwise, insert in a list for future display by
228          * display_error_msgs()
229          */
230         string_list_append(&o->unpack_rejects[e], path);
231         return -1;
232 }
233
234 /*
235  * display all the error messages stored in a nice way
236  */
237 static void display_error_msgs(struct unpack_trees_options *o)
238 {
239         int e, i;
240         int something_displayed = 0;
241         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
242                 struct string_list *rejects = &o->unpack_rejects[e];
243                 if (rejects->nr > 0) {
244                         struct strbuf path = STRBUF_INIT;
245                         something_displayed = 1;
246                         for (i = 0; i < rejects->nr; i++)
247                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
248                         error(ERRORMSG(o, e), super_prefixed(path.buf));
249                         strbuf_release(&path);
250                 }
251                 string_list_clear(rejects, 0);
252         }
253         if (something_displayed)
254                 fprintf(stderr, _("Aborting\n"));
255 }
256
257 static int check_submodule_move_head(const struct cache_entry *ce,
258                                      const char *old_id,
259                                      const char *new_id,
260                                      struct unpack_trees_options *o)
261 {
262         unsigned flags = SUBMODULE_MOVE_HEAD_DRY_RUN;
263         const struct submodule *sub = submodule_from_ce(ce);
264
265         if (!sub)
266                 return 0;
267
268         if (o->reset)
269                 flags |= SUBMODULE_MOVE_HEAD_FORCE;
270
271         if (submodule_move_head(ce->name, old_id, new_id, flags))
272                 return o->gently ? -1 :
273                                    add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
274         return 0;
275 }
276
277 /*
278  * Preform the loading of the repository's gitmodules file.  This function is
279  * used by 'check_update()' to perform loading of the gitmodules file in two
280  * differnt situations:
281  * (1) before removing entries from the working tree if the gitmodules file has
282  *     been marked for removal.  This situation is specified by 'state' == NULL.
283  * (2) before checking out entries to the working tree if the gitmodules file
284  *     has been marked for update.  This situation is specified by 'state' != NULL.
285  */
286 static void load_gitmodules_file(struct index_state *index,
287                                  struct checkout *state)
288 {
289         int pos = index_name_pos(index, GITMODULES_FILE, strlen(GITMODULES_FILE));
290
291         if (pos >= 0) {
292                 struct cache_entry *ce = index->cache[pos];
293                 if (!state && ce->ce_flags & CE_WT_REMOVE) {
294                         repo_read_gitmodules(the_repository);
295                 } else if (state && (ce->ce_flags & CE_UPDATE)) {
296                         submodule_free(the_repository);
297                         checkout_entry(ce, state, NULL);
298                         repo_read_gitmodules(the_repository);
299                 }
300         }
301 }
302
303 /*
304  * Unlink the last component and schedule the leading directories for
305  * removal, such that empty directories get removed.
306  */
307 static void unlink_entry(const struct cache_entry *ce)
308 {
309         const struct submodule *sub = submodule_from_ce(ce);
310         if (sub) {
311                 /* state.force is set at the caller. */
312                 submodule_move_head(ce->name, "HEAD", NULL,
313                                     SUBMODULE_MOVE_HEAD_FORCE);
314         }
315         if (!check_leading_path(ce->name, ce_namelen(ce)))
316                 return;
317         if (remove_or_warn(ce->ce_mode, ce->name))
318                 return;
319         schedule_dir_for_removal(ce->name, ce_namelen(ce));
320 }
321
322 static struct progress *get_progress(struct unpack_trees_options *o)
323 {
324         unsigned cnt = 0, total = 0;
325         struct index_state *index = &o->result;
326
327         if (!o->update || !o->verbose_update)
328                 return NULL;
329
330         for (; cnt < index->cache_nr; cnt++) {
331                 const struct cache_entry *ce = index->cache[cnt];
332                 if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
333                         total++;
334         }
335
336         return start_delayed_progress(_("Checking out files"), total);
337 }
338
339 static void setup_collided_checkout_detection(struct checkout *state,
340                                               struct index_state *index)
341 {
342         int i;
343
344         state->clone = 1;
345         for (i = 0; i < index->cache_nr; i++)
346                 index->cache[i]->ce_flags &= ~CE_MATCHED;
347 }
348
349 static void report_collided_checkout(struct index_state *index)
350 {
351         struct string_list list = STRING_LIST_INIT_NODUP;
352         int i;
353
354         for (i = 0; i < index->cache_nr; i++) {
355                 struct cache_entry *ce = index->cache[i];
356
357                 if (!(ce->ce_flags & CE_MATCHED))
358                         continue;
359
360                 string_list_append(&list, ce->name);
361                 ce->ce_flags &= ~CE_MATCHED;
362         }
363
364         list.cmp = fspathcmp;
365         string_list_sort(&list);
366
367         if (list.nr) {
368                 warning(_("the following paths have collided (e.g. case-sensitive paths\n"
369                           "on a case-insensitive filesystem) and only one from the same\n"
370                           "colliding group is in the working tree:\n"));
371
372                 for (i = 0; i < list.nr; i++)
373                         fprintf(stderr, "  '%s'\n", list.items[i].string);
374         }
375
376         string_list_clear(&list, 0);
377 }
378
379 static int check_updates(struct unpack_trees_options *o)
380 {
381         unsigned cnt = 0;
382         int errs = 0;
383         struct progress *progress;
384         struct index_state *index = &o->result;
385         struct checkout state = CHECKOUT_INIT;
386         int i;
387
388         trace_performance_enter();
389         state.force = 1;
390         state.quiet = 1;
391         state.refresh_cache = 1;
392         state.istate = index;
393
394         if (o->clone)
395                 setup_collided_checkout_detection(&state, index);
396
397         progress = get_progress(o);
398
399         if (o->update)
400                 git_attr_set_direction(GIT_ATTR_CHECKOUT);
401
402         if (should_update_submodules() && o->update && !o->dry_run)
403                 load_gitmodules_file(index, NULL);
404
405         for (i = 0; i < index->cache_nr; i++) {
406                 const struct cache_entry *ce = index->cache[i];
407
408                 if (ce->ce_flags & CE_WT_REMOVE) {
409                         display_progress(progress, ++cnt);
410                         if (o->update && !o->dry_run)
411                                 unlink_entry(ce);
412                 }
413         }
414         remove_marked_cache_entries(index);
415         remove_scheduled_dirs();
416
417         if (should_update_submodules() && o->update && !o->dry_run)
418                 load_gitmodules_file(index, &state);
419
420         enable_delayed_checkout(&state);
421         if (repository_format_partial_clone && o->update && !o->dry_run) {
422                 /*
423                  * Prefetch the objects that are to be checked out in the loop
424                  * below.
425                  */
426                 struct oid_array to_fetch = OID_ARRAY_INIT;
427                 int fetch_if_missing_store = fetch_if_missing;
428                 fetch_if_missing = 0;
429                 for (i = 0; i < index->cache_nr; i++) {
430                         struct cache_entry *ce = index->cache[i];
431                         if ((ce->ce_flags & CE_UPDATE) &&
432                             !S_ISGITLINK(ce->ce_mode)) {
433                                 if (!has_object_file(&ce->oid))
434                                         oid_array_append(&to_fetch, &ce->oid);
435                         }
436                 }
437                 if (to_fetch.nr)
438                         fetch_objects(repository_format_partial_clone,
439                                       to_fetch.oid, to_fetch.nr);
440                 fetch_if_missing = fetch_if_missing_store;
441                 oid_array_clear(&to_fetch);
442         }
443         for (i = 0; i < index->cache_nr; i++) {
444                 struct cache_entry *ce = index->cache[i];
445
446                 if (ce->ce_flags & CE_UPDATE) {
447                         if (ce->ce_flags & CE_WT_REMOVE)
448                                 BUG("both update and delete flags are set on %s",
449                                     ce->name);
450                         display_progress(progress, ++cnt);
451                         ce->ce_flags &= ~CE_UPDATE;
452                         if (o->update && !o->dry_run) {
453                                 errs |= checkout_entry(ce, &state, NULL);
454                         }
455                 }
456         }
457         stop_progress(&progress);
458         errs |= finish_delayed_checkout(&state);
459         if (o->update)
460                 git_attr_set_direction(GIT_ATTR_CHECKIN);
461
462         if (o->clone)
463                 report_collided_checkout(index);
464
465         trace_performance_leave("check_updates");
466         return errs != 0;
467 }
468
469 static int verify_uptodate_sparse(const struct cache_entry *ce,
470                                   struct unpack_trees_options *o);
471 static int verify_absent_sparse(const struct cache_entry *ce,
472                                 enum unpack_trees_error_types,
473                                 struct unpack_trees_options *o);
474
475 static int apply_sparse_checkout(struct index_state *istate,
476                                  struct cache_entry *ce,
477                                  struct unpack_trees_options *o)
478 {
479         int was_skip_worktree = ce_skip_worktree(ce);
480
481         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
482                 ce->ce_flags |= CE_SKIP_WORKTREE;
483         else
484                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
485         if (was_skip_worktree != ce_skip_worktree(ce)) {
486                 ce->ce_flags |= CE_UPDATE_IN_BASE;
487                 mark_fsmonitor_invalid(istate, ce);
488                 istate->cache_changed |= CE_ENTRY_CHANGED;
489         }
490
491         /*
492          * if (!was_skip_worktree && !ce_skip_worktree()) {
493          *      This is perfectly normal. Move on;
494          * }
495          */
496
497         /*
498          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
499          * area as a result of ce_skip_worktree() shortcuts in
500          * verify_absent() and verify_uptodate().
501          * Make sure they don't modify worktree if they are already
502          * outside checkout area
503          */
504         if (was_skip_worktree && ce_skip_worktree(ce)) {
505                 ce->ce_flags &= ~CE_UPDATE;
506
507                 /*
508                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
509                  * on to get that file removed from both index and worktree.
510                  * If that file is already outside worktree area, don't
511                  * bother remove it.
512                  */
513                 if (ce->ce_flags & CE_REMOVE)
514                         ce->ce_flags &= ~CE_WT_REMOVE;
515         }
516
517         if (!was_skip_worktree && ce_skip_worktree(ce)) {
518                 /*
519                  * If CE_UPDATE is set, verify_uptodate() must be called already
520                  * also stat info may have lost after merged_entry() so calling
521                  * verify_uptodate() again may fail
522                  */
523                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
524                         return -1;
525                 ce->ce_flags |= CE_WT_REMOVE;
526                 ce->ce_flags &= ~CE_UPDATE;
527         }
528         if (was_skip_worktree && !ce_skip_worktree(ce)) {
529                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
530                         return -1;
531                 ce->ce_flags |= CE_UPDATE;
532         }
533         return 0;
534 }
535
536 static inline int call_unpack_fn(const struct cache_entry * const *src,
537                                  struct unpack_trees_options *o)
538 {
539         int ret = o->fn(src, o);
540         if (ret > 0)
541                 ret = 0;
542         return ret;
543 }
544
545 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
546 {
547         ce->ce_flags |= CE_UNPACKED;
548
549         if (o->cache_bottom < o->src_index->cache_nr &&
550             o->src_index->cache[o->cache_bottom] == ce) {
551                 int bottom = o->cache_bottom;
552                 while (bottom < o->src_index->cache_nr &&
553                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
554                         bottom++;
555                 o->cache_bottom = bottom;
556         }
557 }
558
559 static void mark_all_ce_unused(struct index_state *index)
560 {
561         int i;
562         for (i = 0; i < index->cache_nr; i++)
563                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
564 }
565
566 static int locate_in_src_index(const struct cache_entry *ce,
567                                struct unpack_trees_options *o)
568 {
569         struct index_state *index = o->src_index;
570         int len = ce_namelen(ce);
571         int pos = index_name_pos(index, ce->name, len);
572         if (pos < 0)
573                 pos = -1 - pos;
574         return pos;
575 }
576
577 /*
578  * We call unpack_index_entry() with an unmerged cache entry
579  * only in diff-index, and it wants a single callback.  Skip
580  * the other unmerged entry with the same name.
581  */
582 static void mark_ce_used_same_name(struct cache_entry *ce,
583                                    struct unpack_trees_options *o)
584 {
585         struct index_state *index = o->src_index;
586         int len = ce_namelen(ce);
587         int pos;
588
589         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
590                 struct cache_entry *next = index->cache[pos];
591                 if (len != ce_namelen(next) ||
592                     memcmp(ce->name, next->name, len))
593                         break;
594                 mark_ce_used(next, o);
595         }
596 }
597
598 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
599 {
600         const struct index_state *index = o->src_index;
601         int pos = o->cache_bottom;
602
603         while (pos < index->cache_nr) {
604                 struct cache_entry *ce = index->cache[pos];
605                 if (!(ce->ce_flags & CE_UNPACKED))
606                         return ce;
607                 pos++;
608         }
609         return NULL;
610 }
611
612 static void add_same_unmerged(const struct cache_entry *ce,
613                               struct unpack_trees_options *o)
614 {
615         struct index_state *index = o->src_index;
616         int len = ce_namelen(ce);
617         int pos = index_name_pos(index, ce->name, len);
618
619         if (0 <= pos)
620                 die("programming error in a caller of mark_ce_used_same_name");
621         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
622                 struct cache_entry *next = index->cache[pos];
623                 if (len != ce_namelen(next) ||
624                     memcmp(ce->name, next->name, len))
625                         break;
626                 add_entry(o, next, 0, 0);
627                 mark_ce_used(next, o);
628         }
629 }
630
631 static int unpack_index_entry(struct cache_entry *ce,
632                               struct unpack_trees_options *o)
633 {
634         const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
635         int ret;
636
637         src[0] = ce;
638
639         mark_ce_used(ce, o);
640         if (ce_stage(ce)) {
641                 if (o->skip_unmerged) {
642                         add_entry(o, ce, 0, 0);
643                         return 0;
644                 }
645         }
646         ret = call_unpack_fn(src, o);
647         if (ce_stage(ce))
648                 mark_ce_used_same_name(ce, o);
649         return ret;
650 }
651
652 static int find_cache_pos(struct traverse_info *, const struct name_entry *);
653
654 static void restore_cache_bottom(struct traverse_info *info, int bottom)
655 {
656         struct unpack_trees_options *o = info->data;
657
658         if (o->diff_index_cached)
659                 return;
660         o->cache_bottom = bottom;
661 }
662
663 static int switch_cache_bottom(struct traverse_info *info)
664 {
665         struct unpack_trees_options *o = info->data;
666         int ret, pos;
667
668         if (o->diff_index_cached)
669                 return 0;
670         ret = o->cache_bottom;
671         pos = find_cache_pos(info->prev, &info->name);
672
673         if (pos < -1)
674                 o->cache_bottom = -2 - pos;
675         else if (pos < 0)
676                 o->cache_bottom = o->src_index->cache_nr;
677         return ret;
678 }
679
680 static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
681 {
682         return name_j->oid && name_k->oid && oideq(name_j->oid, name_k->oid);
683 }
684
685 static int all_trees_same_as_cache_tree(int n, unsigned long dirmask,
686                                         struct name_entry *names,
687                                         struct traverse_info *info)
688 {
689         struct unpack_trees_options *o = info->data;
690         int i;
691
692         if (!o->merge || dirmask != ((1 << n) - 1))
693                 return 0;
694
695         for (i = 1; i < n; i++)
696                 if (!are_same_oid(names, names + i))
697                         return 0;
698
699         return cache_tree_matches_traversal(o->src_index->cache_tree, names, info);
700 }
701
702 static int index_pos_by_traverse_info(struct name_entry *names,
703                                       struct traverse_info *info)
704 {
705         struct unpack_trees_options *o = info->data;
706         int len = traverse_path_len(info, names);
707         char *name = xmalloc(len + 1 /* slash */ + 1 /* NUL */);
708         int pos;
709
710         make_traverse_path(name, info, names);
711         name[len++] = '/';
712         name[len] = '\0';
713         pos = index_name_pos(o->src_index, name, len);
714         if (pos >= 0)
715                 BUG("This is a directory and should not exist in index");
716         pos = -pos - 1;
717         if (!starts_with(o->src_index->cache[pos]->name, name) ||
718             (pos > 0 && starts_with(o->src_index->cache[pos-1]->name, name)))
719                 BUG("pos must point at the first entry in this directory");
720         free(name);
721         return pos;
722 }
723
724 /*
725  * Fast path if we detect that all trees are the same as cache-tree at this
726  * path. We'll walk these trees in an iterative loop using cache-tree/index
727  * instead of ODB since we already know what these trees contain.
728  */
729 static int traverse_by_cache_tree(int pos, int nr_entries, int nr_names,
730                                   struct name_entry *names,
731                                   struct traverse_info *info)
732 {
733         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
734         struct unpack_trees_options *o = info->data;
735         struct cache_entry *tree_ce = NULL;
736         int ce_len = 0;
737         int i, d;
738
739         if (!o->merge)
740                 BUG("We need cache-tree to do this optimization");
741
742         /*
743          * Do what unpack_callback() and unpack_nondirectories() normally
744          * do. But we walk all paths in an iterative loop instead.
745          *
746          * D/F conflicts and higher stage entries are not a concern
747          * because cache-tree would be invalidated and we would never
748          * get here in the first place.
749          */
750         for (i = 0; i < nr_entries; i++) {
751                 int new_ce_len, len, rc;
752
753                 src[0] = o->src_index->cache[pos + i];
754
755                 len = ce_namelen(src[0]);
756                 new_ce_len = cache_entry_size(len);
757
758                 if (new_ce_len > ce_len) {
759                         new_ce_len <<= 1;
760                         tree_ce = xrealloc(tree_ce, new_ce_len);
761                         memset(tree_ce, 0, new_ce_len);
762                         ce_len = new_ce_len;
763
764                         tree_ce->ce_flags = create_ce_flags(0);
765
766                         for (d = 1; d <= nr_names; d++)
767                                 src[d] = tree_ce;
768                 }
769
770                 tree_ce->ce_mode = src[0]->ce_mode;
771                 tree_ce->ce_namelen = len;
772                 oidcpy(&tree_ce->oid, &src[0]->oid);
773                 memcpy(tree_ce->name, src[0]->name, len + 1);
774
775                 rc = call_unpack_fn((const struct cache_entry * const *)src, o);
776                 if (rc < 0) {
777                         free(tree_ce);
778                         return rc;
779                 }
780
781                 mark_ce_used(src[0], o);
782         }
783         free(tree_ce);
784         if (o->debug_unpack)
785                 printf("Unpacked %d entries from %s to %s using cache-tree\n",
786                        nr_entries,
787                        o->src_index->cache[pos]->name,
788                        o->src_index->cache[pos + nr_entries - 1]->name);
789         return 0;
790 }
791
792 static int traverse_trees_recursive(int n, unsigned long dirmask,
793                                     unsigned long df_conflicts,
794                                     struct name_entry *names,
795                                     struct traverse_info *info)
796 {
797         int i, ret, bottom;
798         int nr_buf = 0;
799         struct tree_desc t[MAX_UNPACK_TREES];
800         void *buf[MAX_UNPACK_TREES];
801         struct traverse_info newinfo;
802         struct name_entry *p;
803         int nr_entries;
804
805         nr_entries = all_trees_same_as_cache_tree(n, dirmask, names, info);
806         if (nr_entries > 0) {
807                 struct unpack_trees_options *o = info->data;
808                 int pos = index_pos_by_traverse_info(names, info);
809
810                 if (!o->merge || df_conflicts)
811                         BUG("Wrong condition to get here buddy");
812
813                 /*
814                  * All entries up to 'pos' must have been processed
815                  * (i.e. marked CE_UNPACKED) at this point. But to be safe,
816                  * save and restore cache_bottom anyway to not miss
817                  * unprocessed entries before 'pos'.
818                  */
819                 bottom = o->cache_bottom;
820                 ret = traverse_by_cache_tree(pos, nr_entries, n, names, info);
821                 o->cache_bottom = bottom;
822                 return ret;
823         }
824
825         p = names;
826         while (!p->mode)
827                 p++;
828
829         newinfo = *info;
830         newinfo.prev = info;
831         newinfo.pathspec = info->pathspec;
832         newinfo.name = *p;
833         newinfo.pathlen += tree_entry_len(p) + 1;
834         newinfo.df_conflicts |= df_conflicts;
835
836         /*
837          * Fetch the tree from the ODB for each peer directory in the
838          * n commits.
839          *
840          * For 2- and 3-way traversals, we try to avoid hitting the
841          * ODB twice for the same OID.  This should yield a nice speed
842          * up in checkouts and merges when the commits are similar.
843          *
844          * We don't bother doing the full O(n^2) search for larger n,
845          * because wider traversals don't happen that often and we
846          * avoid the search setup.
847          *
848          * When 2 peer OIDs are the same, we just copy the tree
849          * descriptor data.  This implicitly borrows the buffer
850          * data from the earlier cell.
851          */
852         for (i = 0; i < n; i++, dirmask >>= 1) {
853                 if (i > 0 && are_same_oid(&names[i], &names[i - 1]))
854                         t[i] = t[i - 1];
855                 else if (i > 1 && are_same_oid(&names[i], &names[i - 2]))
856                         t[i] = t[i - 2];
857                 else {
858                         const struct object_id *oid = NULL;
859                         if (dirmask & 1)
860                                 oid = names[i].oid;
861                         buf[nr_buf++] = fill_tree_descriptor(t + i, oid);
862                 }
863         }
864
865         bottom = switch_cache_bottom(&newinfo);
866         ret = traverse_trees(n, t, &newinfo);
867         restore_cache_bottom(&newinfo, bottom);
868
869         for (i = 0; i < nr_buf; i++)
870                 free(buf[i]);
871
872         return ret;
873 }
874
875 /*
876  * Compare the traverse-path to the cache entry without actually
877  * having to generate the textual representation of the traverse
878  * path.
879  *
880  * NOTE! This *only* compares up to the size of the traverse path
881  * itself - the caller needs to do the final check for the cache
882  * entry having more data at the end!
883  */
884 static int do_compare_entry_piecewise(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
885 {
886         int len, pathlen, ce_len;
887         const char *ce_name;
888
889         if (info->prev) {
890                 int cmp = do_compare_entry_piecewise(ce, info->prev,
891                                                      &info->name);
892                 if (cmp)
893                         return cmp;
894         }
895         pathlen = info->pathlen;
896         ce_len = ce_namelen(ce);
897
898         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
899         if (ce_len < pathlen)
900                 return -1;
901
902         ce_len -= pathlen;
903         ce_name = ce->name + pathlen;
904
905         len = tree_entry_len(n);
906         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
907 }
908
909 static int do_compare_entry(const struct cache_entry *ce,
910                             const struct traverse_info *info,
911                             const struct name_entry *n)
912 {
913         int len, pathlen, ce_len;
914         const char *ce_name;
915         int cmp;
916
917         /*
918          * If we have not precomputed the traverse path, it is quicker
919          * to avoid doing so.  But if we have precomputed it,
920          * it is quicker to use the precomputed version.
921          */
922         if (!info->traverse_path)
923                 return do_compare_entry_piecewise(ce, info, n);
924
925         cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
926         if (cmp)
927                 return cmp;
928
929         pathlen = info->pathlen;
930         ce_len = ce_namelen(ce);
931
932         if (ce_len < pathlen)
933                 return -1;
934
935         ce_len -= pathlen;
936         ce_name = ce->name + pathlen;
937
938         len = tree_entry_len(n);
939         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
940 }
941
942 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
943 {
944         int cmp = do_compare_entry(ce, info, n);
945         if (cmp)
946                 return cmp;
947
948         /*
949          * Even if the beginning compared identically, the ce should
950          * compare as bigger than a directory leading up to it!
951          */
952         return ce_namelen(ce) > traverse_path_len(info, n);
953 }
954
955 static int ce_in_traverse_path(const struct cache_entry *ce,
956                                const struct traverse_info *info)
957 {
958         if (!info->prev)
959                 return 1;
960         if (do_compare_entry(ce, info->prev, &info->name))
961                 return 0;
962         /*
963          * If ce (blob) is the same name as the path (which is a tree
964          * we will be descending into), it won't be inside it.
965          */
966         return (info->pathlen < ce_namelen(ce));
967 }
968
969 static struct cache_entry *create_ce_entry(const struct traverse_info *info,
970         const struct name_entry *n,
971         int stage,
972         struct index_state *istate,
973         int is_transient)
974 {
975         int len = traverse_path_len(info, n);
976         struct cache_entry *ce =
977                 is_transient ?
978                 make_empty_transient_cache_entry(len) :
979                 make_empty_cache_entry(istate, len);
980
981         ce->ce_mode = create_ce_mode(n->mode);
982         ce->ce_flags = create_ce_flags(stage);
983         ce->ce_namelen = len;
984         oidcpy(&ce->oid, n->oid);
985         make_traverse_path(ce->name, info, n);
986
987         return ce;
988 }
989
990 /*
991  * Note that traverse_by_cache_tree() duplicates some logic in this function
992  * without actually calling it. If you change the logic here you may need to
993  * check and change there as well.
994  */
995 static int unpack_nondirectories(int n, unsigned long mask,
996                                  unsigned long dirmask,
997                                  struct cache_entry **src,
998                                  const struct name_entry *names,
999                                  const struct traverse_info *info)
1000 {
1001         int i;
1002         struct unpack_trees_options *o = info->data;
1003         unsigned long conflicts = info->df_conflicts | dirmask;
1004
1005         /* Do we have *only* directories? Nothing to do */
1006         if (mask == dirmask && !src[0])
1007                 return 0;
1008
1009         /*
1010          * Ok, we've filled in up to any potential index entry in src[0],
1011          * now do the rest.
1012          */
1013         for (i = 0; i < n; i++) {
1014                 int stage;
1015                 unsigned int bit = 1ul << i;
1016                 if (conflicts & bit) {
1017                         src[i + o->merge] = o->df_conflict_entry;
1018                         continue;
1019                 }
1020                 if (!(mask & bit))
1021                         continue;
1022                 if (!o->merge)
1023                         stage = 0;
1024                 else if (i + 1 < o->head_idx)
1025                         stage = 1;
1026                 else if (i + 1 > o->head_idx)
1027                         stage = 3;
1028                 else
1029                         stage = 2;
1030
1031                 /*
1032                  * If the merge bit is set, then the cache entries are
1033                  * discarded in the following block.  In this case,
1034                  * construct "transient" cache_entries, as they are
1035                  * not stored in the index.  otherwise construct the
1036                  * cache entry from the index aware logic.
1037                  */
1038                 src[i + o->merge] = create_ce_entry(info, names + i, stage, &o->result, o->merge);
1039         }
1040
1041         if (o->merge) {
1042                 int rc = call_unpack_fn((const struct cache_entry * const *)src,
1043                                         o);
1044                 for (i = 0; i < n; i++) {
1045                         struct cache_entry *ce = src[i + o->merge];
1046                         if (ce != o->df_conflict_entry)
1047                                 discard_cache_entry(ce);
1048                 }
1049                 return rc;
1050         }
1051
1052         for (i = 0; i < n; i++)
1053                 if (src[i] && src[i] != o->df_conflict_entry)
1054                         if (do_add_entry(o, src[i], 0, 0))
1055                                 return -1;
1056
1057         return 0;
1058 }
1059
1060 static int unpack_failed(struct unpack_trees_options *o, const char *message)
1061 {
1062         discard_index(&o->result);
1063         if (!o->gently && !o->exiting_early) {
1064                 if (message)
1065                         return error("%s", message);
1066                 return -1;
1067         }
1068         return -1;
1069 }
1070
1071 /*
1072  * The tree traversal is looking at name p.  If we have a matching entry,
1073  * return it.  If name p is a directory in the index, do not return
1074  * anything, as we will want to match it when the traversal descends into
1075  * the directory.
1076  */
1077 static int find_cache_pos(struct traverse_info *info,
1078                           const struct name_entry *p)
1079 {
1080         int pos;
1081         struct unpack_trees_options *o = info->data;
1082         struct index_state *index = o->src_index;
1083         int pfxlen = info->pathlen;
1084         int p_len = tree_entry_len(p);
1085
1086         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
1087                 const struct cache_entry *ce = index->cache[pos];
1088                 const char *ce_name, *ce_slash;
1089                 int cmp, ce_len;
1090
1091                 if (ce->ce_flags & CE_UNPACKED) {
1092                         /*
1093                          * cache_bottom entry is already unpacked, so
1094                          * we can never match it; don't check it
1095                          * again.
1096                          */
1097                         if (pos == o->cache_bottom)
1098                                 ++o->cache_bottom;
1099                         continue;
1100                 }
1101                 if (!ce_in_traverse_path(ce, info)) {
1102                         /*
1103                          * Check if we can skip future cache checks
1104                          * (because we're already past all possible
1105                          * entries in the traverse path).
1106                          */
1107                         if (info->traverse_path) {
1108                                 if (strncmp(ce->name, info->traverse_path,
1109                                             info->pathlen) > 0)
1110                                         break;
1111                         }
1112                         continue;
1113                 }
1114                 ce_name = ce->name + pfxlen;
1115                 ce_slash = strchr(ce_name, '/');
1116                 if (ce_slash)
1117                         ce_len = ce_slash - ce_name;
1118                 else
1119                         ce_len = ce_namelen(ce) - pfxlen;
1120                 cmp = name_compare(p->path, p_len, ce_name, ce_len);
1121                 /*
1122                  * Exact match; if we have a directory we need to
1123                  * delay returning it.
1124                  */
1125                 if (!cmp)
1126                         return ce_slash ? -2 - pos : pos;
1127                 if (0 < cmp)
1128                         continue; /* keep looking */
1129                 /*
1130                  * ce_name sorts after p->path; could it be that we
1131                  * have files under p->path directory in the index?
1132                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
1133                  * have "t/a" in the index.
1134                  */
1135                 if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
1136                     ce_name[p_len] < '/')
1137                         continue; /* keep looking */
1138                 break;
1139         }
1140         return -1;
1141 }
1142
1143 static struct cache_entry *find_cache_entry(struct traverse_info *info,
1144                                             const struct name_entry *p)
1145 {
1146         int pos = find_cache_pos(info, p);
1147         struct unpack_trees_options *o = info->data;
1148
1149         if (0 <= pos)
1150                 return o->src_index->cache[pos];
1151         else
1152                 return NULL;
1153 }
1154
1155 static void debug_path(struct traverse_info *info)
1156 {
1157         if (info->prev) {
1158                 debug_path(info->prev);
1159                 if (*info->prev->name.path)
1160                         putchar('/');
1161         }
1162         printf("%s", info->name.path);
1163 }
1164
1165 static void debug_name_entry(int i, struct name_entry *n)
1166 {
1167         printf("ent#%d %06o %s\n", i,
1168                n->path ? n->mode : 0,
1169                n->path ? n->path : "(missing)");
1170 }
1171
1172 static void debug_unpack_callback(int n,
1173                                   unsigned long mask,
1174                                   unsigned long dirmask,
1175                                   struct name_entry *names,
1176                                   struct traverse_info *info)
1177 {
1178         int i;
1179         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
1180                mask, dirmask, n);
1181         debug_path(info);
1182         putchar('\n');
1183         for (i = 0; i < n; i++)
1184                 debug_name_entry(i, names + i);
1185 }
1186
1187 /*
1188  * Note that traverse_by_cache_tree() duplicates some logic in this function
1189  * without actually calling it. If you change the logic here you may need to
1190  * check and change there as well.
1191  */
1192 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
1193 {
1194         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
1195         struct unpack_trees_options *o = info->data;
1196         const struct name_entry *p = names;
1197
1198         /* Find first entry with a real name (we could use "mask" too) */
1199         while (!p->mode)
1200                 p++;
1201
1202         if (o->debug_unpack)
1203                 debug_unpack_callback(n, mask, dirmask, names, info);
1204
1205         /* Are we supposed to look at the index too? */
1206         if (o->merge) {
1207                 while (1) {
1208                         int cmp;
1209                         struct cache_entry *ce;
1210
1211                         if (o->diff_index_cached)
1212                                 ce = next_cache_entry(o);
1213                         else
1214                                 ce = find_cache_entry(info, p);
1215
1216                         if (!ce)
1217                                 break;
1218                         cmp = compare_entry(ce, info, p);
1219                         if (cmp < 0) {
1220                                 if (unpack_index_entry(ce, o) < 0)
1221                                         return unpack_failed(o, NULL);
1222                                 continue;
1223                         }
1224                         if (!cmp) {
1225                                 if (ce_stage(ce)) {
1226                                         /*
1227                                          * If we skip unmerged index
1228                                          * entries, we'll skip this
1229                                          * entry *and* the tree
1230                                          * entries associated with it!
1231                                          */
1232                                         if (o->skip_unmerged) {
1233                                                 add_same_unmerged(ce, o);
1234                                                 return mask;
1235                                         }
1236                                 }
1237                                 src[0] = ce;
1238                         }
1239                         break;
1240                 }
1241         }
1242
1243         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
1244                 return -1;
1245
1246         if (o->merge && src[0]) {
1247                 if (ce_stage(src[0]))
1248                         mark_ce_used_same_name(src[0], o);
1249                 else
1250                         mark_ce_used(src[0], o);
1251         }
1252
1253         /* Now handle any directories.. */
1254         if (dirmask) {
1255                 /* special case: "diff-index --cached" looking at a tree */
1256                 if (o->diff_index_cached &&
1257                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
1258                         int matches;
1259                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
1260                                                                names, info);
1261                         /*
1262                          * Everything under the name matches; skip the
1263                          * entire hierarchy.  diff_index_cached codepath
1264                          * special cases D/F conflicts in such a way that
1265                          * it does not do any look-ahead, so this is safe.
1266                          */
1267                         if (matches) {
1268                                 o->cache_bottom += matches;
1269                                 return mask;
1270                         }
1271                 }
1272
1273                 if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
1274                                              names, info) < 0)
1275                         return -1;
1276                 return mask;
1277         }
1278
1279         return mask;
1280 }
1281
1282 static int clear_ce_flags_1(struct index_state *istate,
1283                             struct cache_entry **cache, int nr,
1284                             struct strbuf *prefix,
1285                             int select_mask, int clear_mask,
1286                             struct exclude_list *el, int defval);
1287
1288 /* Whole directory matching */
1289 static int clear_ce_flags_dir(struct index_state *istate,
1290                               struct cache_entry **cache, int nr,
1291                               struct strbuf *prefix,
1292                               char *basename,
1293                               int select_mask, int clear_mask,
1294                               struct exclude_list *el, int defval)
1295 {
1296         struct cache_entry **cache_end;
1297         int dtype = DT_DIR;
1298         int ret = is_excluded_from_list(prefix->buf, prefix->len,
1299                                         basename, &dtype, el, istate);
1300         int rc;
1301
1302         strbuf_addch(prefix, '/');
1303
1304         /* If undecided, use matching result of parent dir in defval */
1305         if (ret < 0)
1306                 ret = defval;
1307
1308         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
1309                 struct cache_entry *ce = *cache_end;
1310                 if (strncmp(ce->name, prefix->buf, prefix->len))
1311                         break;
1312         }
1313
1314         /*
1315          * TODO: check el, if there are no patterns that may conflict
1316          * with ret (iow, we know in advance the incl/excl
1317          * decision for the entire directory), clear flag here without
1318          * calling clear_ce_flags_1(). That function will call
1319          * the expensive is_excluded_from_list() on every entry.
1320          */
1321         rc = clear_ce_flags_1(istate, cache, cache_end - cache,
1322                               prefix,
1323                               select_mask, clear_mask,
1324                               el, ret);
1325         strbuf_setlen(prefix, prefix->len - 1);
1326         return rc;
1327 }
1328
1329 /*
1330  * Traverse the index, find every entry that matches according to
1331  * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
1332  * number of traversed entries.
1333  *
1334  * If select_mask is non-zero, only entries whose ce_flags has on of
1335  * those bits enabled are traversed.
1336  *
1337  * cache        : pointer to an index entry
1338  * prefix_len   : an offset to its path
1339  *
1340  * The current path ("prefix") including the trailing '/' is
1341  *   cache[0]->name[0..(prefix_len-1)]
1342  * Top level path has prefix_len zero.
1343  */
1344 static int clear_ce_flags_1(struct index_state *istate,
1345                             struct cache_entry **cache, int nr,
1346                             struct strbuf *prefix,
1347                             int select_mask, int clear_mask,
1348                             struct exclude_list *el, int defval)
1349 {
1350         struct cache_entry **cache_end = cache + nr;
1351
1352         /*
1353          * Process all entries that have the given prefix and meet
1354          * select_mask condition
1355          */
1356         while(cache != cache_end) {
1357                 struct cache_entry *ce = *cache;
1358                 const char *name, *slash;
1359                 int len, dtype, ret;
1360
1361                 if (select_mask && !(ce->ce_flags & select_mask)) {
1362                         cache++;
1363                         continue;
1364                 }
1365
1366                 if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
1367                         break;
1368
1369                 name = ce->name + prefix->len;
1370                 slash = strchr(name, '/');
1371
1372                 /* If it's a directory, try whole directory match first */
1373                 if (slash) {
1374                         int processed;
1375
1376                         len = slash - name;
1377                         strbuf_add(prefix, name, len);
1378
1379                         processed = clear_ce_flags_dir(istate, cache, cache_end - cache,
1380                                                        prefix,
1381                                                        prefix->buf + prefix->len - len,
1382                                                        select_mask, clear_mask,
1383                                                        el, defval);
1384
1385                         /* clear_c_f_dir eats a whole dir already? */
1386                         if (processed) {
1387                                 cache += processed;
1388                                 strbuf_setlen(prefix, prefix->len - len);
1389                                 continue;
1390                         }
1391
1392                         strbuf_addch(prefix, '/');
1393                         cache += clear_ce_flags_1(istate, cache, cache_end - cache,
1394                                                   prefix,
1395                                                   select_mask, clear_mask, el, defval);
1396                         strbuf_setlen(prefix, prefix->len - len - 1);
1397                         continue;
1398                 }
1399
1400                 /* Non-directory */
1401                 dtype = ce_to_dtype(ce);
1402                 ret = is_excluded_from_list(ce->name, ce_namelen(ce),
1403                                             name, &dtype, el, istate);
1404                 if (ret < 0)
1405                         ret = defval;
1406                 if (ret > 0)
1407                         ce->ce_flags &= ~clear_mask;
1408                 cache++;
1409         }
1410         return nr - (cache_end - cache);
1411 }
1412
1413 static int clear_ce_flags(struct index_state *istate,
1414                           int select_mask, int clear_mask,
1415                           struct exclude_list *el)
1416 {
1417         static struct strbuf prefix = STRBUF_INIT;
1418
1419         strbuf_reset(&prefix);
1420
1421         return clear_ce_flags_1(istate,
1422                                 istate->cache,
1423                                 istate->cache_nr,
1424                                 &prefix,
1425                                 select_mask, clear_mask,
1426                                 el, 0);
1427 }
1428
1429 /*
1430  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1431  */
1432 static void mark_new_skip_worktree(struct exclude_list *el,
1433                                    struct index_state *istate,
1434                                    int select_flag, int skip_wt_flag)
1435 {
1436         int i;
1437
1438         /*
1439          * 1. Pretend the narrowest worktree: only unmerged entries
1440          * are checked out
1441          */
1442         for (i = 0; i < istate->cache_nr; i++) {
1443                 struct cache_entry *ce = istate->cache[i];
1444
1445                 if (select_flag && !(ce->ce_flags & select_flag))
1446                         continue;
1447
1448                 if (!ce_stage(ce) && !(ce->ce_flags & CE_CONFLICTED))
1449                         ce->ce_flags |= skip_wt_flag;
1450                 else
1451                         ce->ce_flags &= ~skip_wt_flag;
1452         }
1453
1454         /*
1455          * 2. Widen worktree according to sparse-checkout file.
1456          * Matched entries will have skip_wt_flag cleared (i.e. "in")
1457          */
1458         clear_ce_flags(istate, select_flag, skip_wt_flag, el);
1459 }
1460
1461 static int verify_absent(const struct cache_entry *,
1462                          enum unpack_trees_error_types,
1463                          struct unpack_trees_options *);
1464 /*
1465  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1466  * resulting index, -2 on failure to reflect the changes to the work tree.
1467  *
1468  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1469  */
1470 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1471 {
1472         int i, ret;
1473         static struct cache_entry *dfc;
1474         struct exclude_list el;
1475
1476         if (len > MAX_UNPACK_TREES)
1477                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1478
1479         trace_performance_enter();
1480         memset(&el, 0, sizeof(el));
1481         if (!core_apply_sparse_checkout || !o->update)
1482                 o->skip_sparse_checkout = 1;
1483         if (!o->skip_sparse_checkout) {
1484                 char *sparse = git_pathdup("info/sparse-checkout");
1485                 if (add_excludes_from_file_to_list(sparse, "", 0, &el, NULL) < 0)
1486                         o->skip_sparse_checkout = 1;
1487                 else
1488                         o->el = &el;
1489                 free(sparse);
1490         }
1491
1492         memset(&o->result, 0, sizeof(o->result));
1493         o->result.initialized = 1;
1494         o->result.timestamp.sec = o->src_index->timestamp.sec;
1495         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1496         o->result.version = o->src_index->version;
1497         if (!o->src_index->split_index) {
1498                 o->result.split_index = NULL;
1499         } else if (o->src_index == o->dst_index) {
1500                 /*
1501                  * o->dst_index (and thus o->src_index) will be discarded
1502                  * and overwritten with o->result at the end of this function,
1503                  * so just use src_index's split_index to avoid having to
1504                  * create a new one.
1505                  */
1506                 o->result.split_index = o->src_index->split_index;
1507                 o->result.split_index->refcount++;
1508         } else {
1509                 o->result.split_index = init_split_index(&o->result);
1510         }
1511         oidcpy(&o->result.oid, &o->src_index->oid);
1512         o->merge_size = len;
1513         mark_all_ce_unused(o->src_index);
1514
1515         /*
1516          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1517          */
1518         if (!o->skip_sparse_checkout)
1519                 mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1520
1521         if (!dfc)
1522                 dfc = xcalloc(1, cache_entry_size(0));
1523         o->df_conflict_entry = dfc;
1524
1525         if (len) {
1526                 const char *prefix = o->prefix ? o->prefix : "";
1527                 struct traverse_info info;
1528
1529                 setup_traverse_info(&info, prefix);
1530                 info.fn = unpack_callback;
1531                 info.data = o;
1532                 info.show_all_errors = o->show_all_errors;
1533                 info.pathspec = o->pathspec;
1534
1535                 if (o->prefix) {
1536                         /*
1537                          * Unpack existing index entries that sort before the
1538                          * prefix the tree is spliced into.  Note that o->merge
1539                          * is always true in this case.
1540                          */
1541                         while (1) {
1542                                 struct cache_entry *ce = next_cache_entry(o);
1543                                 if (!ce)
1544                                         break;
1545                                 if (ce_in_traverse_path(ce, &info))
1546                                         break;
1547                                 if (unpack_index_entry(ce, o) < 0)
1548                                         goto return_failed;
1549                         }
1550                 }
1551
1552                 trace_performance_enter();
1553                 ret = traverse_trees(len, t, &info);
1554                 trace_performance_leave("traverse_trees");
1555                 if (ret < 0)
1556                         goto return_failed;
1557         }
1558
1559         /* Any left-over entries in the index? */
1560         if (o->merge) {
1561                 while (1) {
1562                         struct cache_entry *ce = next_cache_entry(o);
1563                         if (!ce)
1564                                 break;
1565                         if (unpack_index_entry(ce, o) < 0)
1566                                 goto return_failed;
1567                 }
1568         }
1569         mark_all_ce_unused(o->src_index);
1570
1571         if (o->trivial_merges_only && o->nontrivial_merge) {
1572                 ret = unpack_failed(o, "Merge requires file-level merging");
1573                 goto done;
1574         }
1575
1576         if (!o->skip_sparse_checkout) {
1577                 int empty_worktree = 1;
1578
1579                 /*
1580                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1581                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1582                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1583                  */
1584                 mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1585
1586                 ret = 0;
1587                 for (i = 0; i < o->result.cache_nr; i++) {
1588                         struct cache_entry *ce = o->result.cache[i];
1589
1590                         /*
1591                          * Entries marked with CE_ADDED in merged_entry() do not have
1592                          * verify_absent() check (the check is effectively disabled
1593                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1594                          *
1595                          * Do the real check now because we have had
1596                          * correct CE_NEW_SKIP_WORKTREE
1597                          */
1598                         if (ce->ce_flags & CE_ADDED &&
1599                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1600                                 if (!o->show_all_errors)
1601                                         goto return_failed;
1602                                 ret = -1;
1603                         }
1604
1605                         if (apply_sparse_checkout(&o->result, ce, o)) {
1606                                 if (!o->show_all_errors)
1607                                         goto return_failed;
1608                                 ret = -1;
1609                         }
1610                         if (!ce_skip_worktree(ce))
1611                                 empty_worktree = 0;
1612
1613                 }
1614                 if (ret < 0)
1615                         goto return_failed;
1616                 /*
1617                  * Sparse checkout is meant to narrow down checkout area
1618                  * but it does not make sense to narrow down to empty working
1619                  * tree. This is usually a mistake in sparse checkout rules.
1620                  * Do not allow users to do that.
1621                  */
1622                 if (o->result.cache_nr && empty_worktree) {
1623                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1624                         goto done;
1625                 }
1626         }
1627
1628         ret = check_updates(o) ? (-2) : 0;
1629         if (o->dst_index) {
1630                 move_index_extensions(&o->result, o->src_index);
1631                 if (!ret) {
1632                         if (git_env_bool("GIT_TEST_CHECK_CACHE_TREE", 0))
1633                                 cache_tree_verify(the_repository, &o->result);
1634                         if (!o->result.cache_tree)
1635                                 o->result.cache_tree = cache_tree();
1636                         if (!cache_tree_fully_valid(o->result.cache_tree))
1637                                 cache_tree_update(&o->result,
1638                                                   WRITE_TREE_SILENT |
1639                                                   WRITE_TREE_REPAIR);
1640                 }
1641                 discard_index(o->dst_index);
1642                 *o->dst_index = o->result;
1643         } else {
1644                 discard_index(&o->result);
1645         }
1646         o->src_index = NULL;
1647
1648 done:
1649         trace_performance_leave("unpack_trees");
1650         clear_exclude_list(&el);
1651         return ret;
1652
1653 return_failed:
1654         if (o->show_all_errors)
1655                 display_error_msgs(o);
1656         mark_all_ce_unused(o->src_index);
1657         ret = unpack_failed(o, NULL);
1658         if (o->exiting_early)
1659                 ret = 0;
1660         goto done;
1661 }
1662
1663 /* Here come the merge functions */
1664
1665 static int reject_merge(const struct cache_entry *ce,
1666                         struct unpack_trees_options *o)
1667 {
1668         return o->gently ? -1 :
1669                 add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1670 }
1671
1672 static int same(const struct cache_entry *a, const struct cache_entry *b)
1673 {
1674         if (!!a != !!b)
1675                 return 0;
1676         if (!a && !b)
1677                 return 1;
1678         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1679                 return 0;
1680         return a->ce_mode == b->ce_mode &&
1681                oideq(&a->oid, &b->oid);
1682 }
1683
1684
1685 /*
1686  * When a CE gets turned into an unmerged entry, we
1687  * want it to be up-to-date
1688  */
1689 static int verify_uptodate_1(const struct cache_entry *ce,
1690                              struct unpack_trees_options *o,
1691                              enum unpack_trees_error_types error_type)
1692 {
1693         struct stat st;
1694
1695         if (o->index_only)
1696                 return 0;
1697
1698         /*
1699          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1700          * if this entry is truly up-to-date because this file may be
1701          * overwritten.
1702          */
1703         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1704                 ; /* keep checking */
1705         else if (o->reset || ce_uptodate(ce))
1706                 return 0;
1707
1708         if (!lstat(ce->name, &st)) {
1709                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1710                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1711
1712                 if (submodule_from_ce(ce)) {
1713                         int r = check_submodule_move_head(ce,
1714                                 "HEAD", oid_to_hex(&ce->oid), o);
1715                         if (r)
1716                                 return o->gently ? -1 :
1717                                         add_rejected_path(o, error_type, ce->name);
1718                         return 0;
1719                 }
1720
1721                 if (!changed)
1722                         return 0;
1723                 /*
1724                  * Historic default policy was to allow submodule to be out
1725                  * of sync wrt the superproject index. If the submodule was
1726                  * not considered interesting above, we don't care here.
1727                  */
1728                 if (S_ISGITLINK(ce->ce_mode))
1729                         return 0;
1730
1731                 errno = 0;
1732         }
1733         if (errno == ENOENT)
1734                 return 0;
1735         return o->gently ? -1 :
1736                 add_rejected_path(o, error_type, ce->name);
1737 }
1738
1739 int verify_uptodate(const struct cache_entry *ce,
1740                     struct unpack_trees_options *o)
1741 {
1742         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1743                 return 0;
1744         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1745 }
1746
1747 static int verify_uptodate_sparse(const struct cache_entry *ce,
1748                                   struct unpack_trees_options *o)
1749 {
1750         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1751 }
1752
1753 /*
1754  * TODO: We should actually invalidate o->result, not src_index [1].
1755  * But since cache tree and untracked cache both are not copied to
1756  * o->result until unpacking is complete, we invalidate them on
1757  * src_index instead with the assumption that they will be copied to
1758  * dst_index at the end.
1759  *
1760  * [1] src_index->cache_tree is also used in unpack_callback() so if
1761  * we invalidate o->result, we need to update it to use
1762  * o->result.cache_tree as well.
1763  */
1764 static void invalidate_ce_path(const struct cache_entry *ce,
1765                                struct unpack_trees_options *o)
1766 {
1767         if (!ce)
1768                 return;
1769         cache_tree_invalidate_path(o->src_index, ce->name);
1770         untracked_cache_invalidate_path(o->src_index, ce->name, 1);
1771 }
1772
1773 /*
1774  * Check that checking out ce->sha1 in subdir ce->name is not
1775  * going to overwrite any working files.
1776  *
1777  * Currently, git does not checkout subprojects during a superproject
1778  * checkout, so it is not going to overwrite anything.
1779  */
1780 static int verify_clean_submodule(const char *old_sha1,
1781                                   const struct cache_entry *ce,
1782                                   enum unpack_trees_error_types error_type,
1783                                   struct unpack_trees_options *o)
1784 {
1785         if (!submodule_from_ce(ce))
1786                 return 0;
1787
1788         return check_submodule_move_head(ce, old_sha1,
1789                                          oid_to_hex(&ce->oid), o);
1790 }
1791
1792 static int verify_clean_subdirectory(const struct cache_entry *ce,
1793                                      enum unpack_trees_error_types error_type,
1794                                      struct unpack_trees_options *o)
1795 {
1796         /*
1797          * we are about to extract "ce->name"; we would not want to lose
1798          * anything in the existing directory there.
1799          */
1800         int namelen;
1801         int i;
1802         struct dir_struct d;
1803         char *pathbuf;
1804         int cnt = 0;
1805
1806         if (S_ISGITLINK(ce->ce_mode)) {
1807                 struct object_id oid;
1808                 int sub_head = resolve_gitlink_ref(ce->name, "HEAD", &oid);
1809                 /*
1810                  * If we are not going to update the submodule, then
1811                  * we don't care.
1812                  */
1813                 if (!sub_head && oideq(&oid, &ce->oid))
1814                         return 0;
1815                 return verify_clean_submodule(sub_head ? NULL : oid_to_hex(&oid),
1816                                               ce, error_type, o);
1817         }
1818
1819         /*
1820          * First let's make sure we do not have a local modification
1821          * in that directory.
1822          */
1823         namelen = ce_namelen(ce);
1824         for (i = locate_in_src_index(ce, o);
1825              i < o->src_index->cache_nr;
1826              i++) {
1827                 struct cache_entry *ce2 = o->src_index->cache[i];
1828                 int len = ce_namelen(ce2);
1829                 if (len < namelen ||
1830                     strncmp(ce->name, ce2->name, namelen) ||
1831                     ce2->name[namelen] != '/')
1832                         break;
1833                 /*
1834                  * ce2->name is an entry in the subdirectory to be
1835                  * removed.
1836                  */
1837                 if (!ce_stage(ce2)) {
1838                         if (verify_uptodate(ce2, o))
1839                                 return -1;
1840                         add_entry(o, ce2, CE_REMOVE, 0);
1841                         invalidate_ce_path(ce, o);
1842                         mark_ce_used(ce2, o);
1843                 }
1844                 cnt++;
1845         }
1846
1847         /*
1848          * Then we need to make sure that we do not lose a locally
1849          * present file that is not ignored.
1850          */
1851         pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1852
1853         memset(&d, 0, sizeof(d));
1854         if (o->dir)
1855                 d.exclude_per_dir = o->dir->exclude_per_dir;
1856         i = read_directory(&d, o->src_index, pathbuf, namelen+1, NULL);
1857         if (i)
1858                 return o->gently ? -1 :
1859                         add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1860         free(pathbuf);
1861         return cnt;
1862 }
1863
1864 /*
1865  * This gets called when there was no index entry for the tree entry 'dst',
1866  * but we found a file in the working tree that 'lstat()' said was fine,
1867  * and we're on a case-insensitive filesystem.
1868  *
1869  * See if we can find a case-insensitive match in the index that also
1870  * matches the stat information, and assume it's that other file!
1871  */
1872 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1873 {
1874         const struct cache_entry *src;
1875
1876         src = index_file_exists(o->src_index, name, len, 1);
1877         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1878 }
1879
1880 static int check_ok_to_remove(const char *name, int len, int dtype,
1881                               const struct cache_entry *ce, struct stat *st,
1882                               enum unpack_trees_error_types error_type,
1883                               struct unpack_trees_options *o)
1884 {
1885         const struct cache_entry *result;
1886
1887         /*
1888          * It may be that the 'lstat()' succeeded even though
1889          * target 'ce' was absent, because there is an old
1890          * entry that is different only in case..
1891          *
1892          * Ignore that lstat() if it matches.
1893          */
1894         if (ignore_case && icase_exists(o, name, len, st))
1895                 return 0;
1896
1897         if (o->dir &&
1898             is_excluded(o->dir, o->src_index, name, &dtype))
1899                 /*
1900                  * ce->name is explicitly excluded, so it is Ok to
1901                  * overwrite it.
1902                  */
1903                 return 0;
1904         if (S_ISDIR(st->st_mode)) {
1905                 /*
1906                  * We are checking out path "foo" and
1907                  * found "foo/." in the working tree.
1908                  * This is tricky -- if we have modified
1909                  * files that are in "foo/" we would lose
1910                  * them.
1911                  */
1912                 if (verify_clean_subdirectory(ce, error_type, o) < 0)
1913                         return -1;
1914                 return 0;
1915         }
1916
1917         /*
1918          * The previous round may already have decided to
1919          * delete this path, which is in a subdirectory that
1920          * is being replaced with a blob.
1921          */
1922         result = index_file_exists(&o->result, name, len, 0);
1923         if (result) {
1924                 if (result->ce_flags & CE_REMOVE)
1925                         return 0;
1926         }
1927
1928         return o->gently ? -1 :
1929                 add_rejected_path(o, error_type, name);
1930 }
1931
1932 /*
1933  * We do not want to remove or overwrite a working tree file that
1934  * is not tracked, unless it is ignored.
1935  */
1936 static int verify_absent_1(const struct cache_entry *ce,
1937                            enum unpack_trees_error_types error_type,
1938                            struct unpack_trees_options *o)
1939 {
1940         int len;
1941         struct stat st;
1942
1943         if (o->index_only || o->reset || !o->update)
1944                 return 0;
1945
1946         len = check_leading_path(ce->name, ce_namelen(ce));
1947         if (!len)
1948                 return 0;
1949         else if (len > 0) {
1950                 char *path;
1951                 int ret;
1952
1953                 path = xmemdupz(ce->name, len);
1954                 if (lstat(path, &st))
1955                         ret = error_errno("cannot stat '%s'", path);
1956                 else {
1957                         if (submodule_from_ce(ce))
1958                                 ret = check_submodule_move_head(ce,
1959                                                                 oid_to_hex(&ce->oid),
1960                                                                 NULL, o);
1961                         else
1962                                 ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
1963                                                          &st, error_type, o);
1964                 }
1965                 free(path);
1966                 return ret;
1967         } else if (lstat(ce->name, &st)) {
1968                 if (errno != ENOENT)
1969                         return error_errno("cannot stat '%s'", ce->name);
1970                 return 0;
1971         } else {
1972                 if (submodule_from_ce(ce))
1973                         return check_submodule_move_head(ce, oid_to_hex(&ce->oid),
1974                                                          NULL, o);
1975
1976                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1977                                           ce_to_dtype(ce), ce, &st,
1978                                           error_type, o);
1979         }
1980 }
1981
1982 static int verify_absent(const struct cache_entry *ce,
1983                          enum unpack_trees_error_types error_type,
1984                          struct unpack_trees_options *o)
1985 {
1986         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1987                 return 0;
1988         return verify_absent_1(ce, error_type, o);
1989 }
1990
1991 static int verify_absent_sparse(const struct cache_entry *ce,
1992                                 enum unpack_trees_error_types error_type,
1993                                 struct unpack_trees_options *o)
1994 {
1995         enum unpack_trees_error_types orphaned_error = error_type;
1996         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1997                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1998
1999         return verify_absent_1(ce, orphaned_error, o);
2000 }
2001
2002 static int merged_entry(const struct cache_entry *ce,
2003                         const struct cache_entry *old,
2004                         struct unpack_trees_options *o)
2005 {
2006         int update = CE_UPDATE;
2007         struct cache_entry *merge = dup_cache_entry(ce, &o->result);
2008
2009         if (!old) {
2010                 /*
2011                  * New index entries. In sparse checkout, the following
2012                  * verify_absent() will be delayed until after
2013                  * traverse_trees() finishes in unpack_trees(), then:
2014                  *
2015                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
2016                  *  - verify_absent() be called again, this time with
2017                  *    correct CE_NEW_SKIP_WORKTREE
2018                  *
2019                  * verify_absent() call here does nothing in sparse
2020                  * checkout (i.e. o->skip_sparse_checkout == 0)
2021                  */
2022                 update |= CE_ADDED;
2023                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
2024
2025                 if (verify_absent(merge,
2026                                   ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
2027                         discard_cache_entry(merge);
2028                         return -1;
2029                 }
2030                 invalidate_ce_path(merge, o);
2031
2032                 if (submodule_from_ce(ce)) {
2033                         int ret = check_submodule_move_head(ce, NULL,
2034                                                             oid_to_hex(&ce->oid),
2035                                                             o);
2036                         if (ret)
2037                                 return ret;
2038                 }
2039
2040         } else if (!(old->ce_flags & CE_CONFLICTED)) {
2041                 /*
2042                  * See if we can re-use the old CE directly?
2043                  * That way we get the uptodate stat info.
2044                  *
2045                  * This also removes the UPDATE flag on a match; otherwise
2046                  * we will end up overwriting local changes in the work tree.
2047                  */
2048                 if (same(old, merge)) {
2049                         copy_cache_entry(merge, old);
2050                         update = 0;
2051                 } else {
2052                         if (verify_uptodate(old, o)) {
2053                                 discard_cache_entry(merge);
2054                                 return -1;
2055                         }
2056                         /* Migrate old flags over */
2057                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
2058                         invalidate_ce_path(old, o);
2059                 }
2060
2061                 if (submodule_from_ce(ce)) {
2062                         int ret = check_submodule_move_head(ce, oid_to_hex(&old->oid),
2063                                                             oid_to_hex(&ce->oid),
2064                                                             o);
2065                         if (ret)
2066                                 return ret;
2067                 }
2068         } else {
2069                 /*
2070                  * Previously unmerged entry left as an existence
2071                  * marker by read_index_unmerged();
2072                  */
2073                 invalidate_ce_path(old, o);
2074         }
2075
2076         do_add_entry(o, merge, update, CE_STAGEMASK);
2077         return 1;
2078 }
2079
2080 static int deleted_entry(const struct cache_entry *ce,
2081                          const struct cache_entry *old,
2082                          struct unpack_trees_options *o)
2083 {
2084         /* Did it exist in the index? */
2085         if (!old) {
2086                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
2087                         return -1;
2088                 return 0;
2089         }
2090         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
2091                 return -1;
2092         add_entry(o, ce, CE_REMOVE, 0);
2093         invalidate_ce_path(ce, o);
2094         return 1;
2095 }
2096
2097 static int keep_entry(const struct cache_entry *ce,
2098                       struct unpack_trees_options *o)
2099 {
2100         add_entry(o, ce, 0, 0);
2101         if (ce_stage(ce))
2102                 invalidate_ce_path(ce, o);
2103         return 1;
2104 }
2105
2106 #if DBRT_DEBUG
2107 static void show_stage_entry(FILE *o,
2108                              const char *label, const struct cache_entry *ce)
2109 {
2110         if (!ce)
2111                 fprintf(o, "%s (missing)\n", label);
2112         else
2113                 fprintf(o, "%s%06o %s %d\t%s\n",
2114                         label,
2115                         ce->ce_mode,
2116                         oid_to_hex(&ce->oid),
2117                         ce_stage(ce),
2118                         ce->name);
2119 }
2120 #endif
2121
2122 int threeway_merge(const struct cache_entry * const *stages,
2123                    struct unpack_trees_options *o)
2124 {
2125         const struct cache_entry *index;
2126         const struct cache_entry *head;
2127         const struct cache_entry *remote = stages[o->head_idx + 1];
2128         int count;
2129         int head_match = 0;
2130         int remote_match = 0;
2131
2132         int df_conflict_head = 0;
2133         int df_conflict_remote = 0;
2134
2135         int any_anc_missing = 0;
2136         int no_anc_exists = 1;
2137         int i;
2138
2139         for (i = 1; i < o->head_idx; i++) {
2140                 if (!stages[i] || stages[i] == o->df_conflict_entry)
2141                         any_anc_missing = 1;
2142                 else
2143                         no_anc_exists = 0;
2144         }
2145
2146         index = stages[0];
2147         head = stages[o->head_idx];
2148
2149         if (head == o->df_conflict_entry) {
2150                 df_conflict_head = 1;
2151                 head = NULL;
2152         }
2153
2154         if (remote == o->df_conflict_entry) {
2155                 df_conflict_remote = 1;
2156                 remote = NULL;
2157         }
2158
2159         /*
2160          * First, if there's a #16 situation, note that to prevent #13
2161          * and #14.
2162          */
2163         if (!same(remote, head)) {
2164                 for (i = 1; i < o->head_idx; i++) {
2165                         if (same(stages[i], head)) {
2166                                 head_match = i;
2167                         }
2168                         if (same(stages[i], remote)) {
2169                                 remote_match = i;
2170                         }
2171                 }
2172         }
2173
2174         /*
2175          * We start with cases where the index is allowed to match
2176          * something other than the head: #14(ALT) and #2ALT, where it
2177          * is permitted to match the result instead.
2178          */
2179         /* #14, #14ALT, #2ALT */
2180         if (remote && !df_conflict_head && head_match && !remote_match) {
2181                 if (index && !same(index, remote) && !same(index, head))
2182                         return reject_merge(index, o);
2183                 return merged_entry(remote, index, o);
2184         }
2185         /*
2186          * If we have an entry in the index cache, then we want to
2187          * make sure that it matches head.
2188          */
2189         if (index && !same(index, head))
2190                 return reject_merge(index, o);
2191
2192         if (head) {
2193                 /* #5ALT, #15 */
2194                 if (same(head, remote))
2195                         return merged_entry(head, index, o);
2196                 /* #13, #3ALT */
2197                 if (!df_conflict_remote && remote_match && !head_match)
2198                         return merged_entry(head, index, o);
2199         }
2200
2201         /* #1 */
2202         if (!head && !remote && any_anc_missing)
2203                 return 0;
2204
2205         /*
2206          * Under the "aggressive" rule, we resolve mostly trivial
2207          * cases that we historically had git-merge-one-file resolve.
2208          */
2209         if (o->aggressive) {
2210                 int head_deleted = !head;
2211                 int remote_deleted = !remote;
2212                 const struct cache_entry *ce = NULL;
2213
2214                 if (index)
2215                         ce = index;
2216                 else if (head)
2217                         ce = head;
2218                 else if (remote)
2219                         ce = remote;
2220                 else {
2221                         for (i = 1; i < o->head_idx; i++) {
2222                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
2223                                         ce = stages[i];
2224                                         break;
2225                                 }
2226                         }
2227                 }
2228
2229                 /*
2230                  * Deleted in both.
2231                  * Deleted in one and unchanged in the other.
2232                  */
2233                 if ((head_deleted && remote_deleted) ||
2234                     (head_deleted && remote && remote_match) ||
2235                     (remote_deleted && head && head_match)) {
2236                         if (index)
2237                                 return deleted_entry(index, index, o);
2238                         if (ce && !head_deleted) {
2239                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
2240                                         return -1;
2241                         }
2242                         return 0;
2243                 }
2244                 /*
2245                  * Added in both, identically.
2246                  */
2247                 if (no_anc_exists && head && remote && same(head, remote))
2248                         return merged_entry(head, index, o);
2249
2250         }
2251
2252         /* Below are "no merge" cases, which require that the index be
2253          * up-to-date to avoid the files getting overwritten with
2254          * conflict resolution files.
2255          */
2256         if (index) {
2257                 if (verify_uptodate(index, o))
2258                         return -1;
2259         }
2260
2261         o->nontrivial_merge = 1;
2262
2263         /* #2, #3, #4, #6, #7, #9, #10, #11. */
2264         count = 0;
2265         if (!head_match || !remote_match) {
2266                 for (i = 1; i < o->head_idx; i++) {
2267                         if (stages[i] && stages[i] != o->df_conflict_entry) {
2268                                 keep_entry(stages[i], o);
2269                                 count++;
2270                                 break;
2271                         }
2272                 }
2273         }
2274 #if DBRT_DEBUG
2275         else {
2276                 fprintf(stderr, "read-tree: warning #16 detected\n");
2277                 show_stage_entry(stderr, "head   ", stages[head_match]);
2278                 show_stage_entry(stderr, "remote ", stages[remote_match]);
2279         }
2280 #endif
2281         if (head) { count += keep_entry(head, o); }
2282         if (remote) { count += keep_entry(remote, o); }
2283         return count;
2284 }
2285
2286 /*
2287  * Two-way merge.
2288  *
2289  * The rule is to "carry forward" what is in the index without losing
2290  * information across a "fast-forward", favoring a successful merge
2291  * over a merge failure when it makes sense.  For details of the
2292  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
2293  *
2294  */
2295 int twoway_merge(const struct cache_entry * const *src,
2296                  struct unpack_trees_options *o)
2297 {
2298         const struct cache_entry *current = src[0];
2299         const struct cache_entry *oldtree = src[1];
2300         const struct cache_entry *newtree = src[2];
2301
2302         if (o->merge_size != 2)
2303                 return error("Cannot do a twoway merge of %d trees",
2304                              o->merge_size);
2305
2306         if (oldtree == o->df_conflict_entry)
2307                 oldtree = NULL;
2308         if (newtree == o->df_conflict_entry)
2309                 newtree = NULL;
2310
2311         if (current) {
2312                 if (current->ce_flags & CE_CONFLICTED) {
2313                         if (same(oldtree, newtree) || o->reset) {
2314                                 if (!newtree)
2315                                         return deleted_entry(current, current, o);
2316                                 else
2317                                         return merged_entry(newtree, current, o);
2318                         }
2319                         return reject_merge(current, o);
2320                 } else if ((!oldtree && !newtree) || /* 4 and 5 */
2321                          (!oldtree && newtree &&
2322                           same(current, newtree)) || /* 6 and 7 */
2323                          (oldtree && newtree &&
2324                           same(oldtree, newtree)) || /* 14 and 15 */
2325                          (oldtree && newtree &&
2326                           !same(oldtree, newtree) && /* 18 and 19 */
2327                           same(current, newtree))) {
2328                         return keep_entry(current, o);
2329                 } else if (oldtree && !newtree && same(current, oldtree)) {
2330                         /* 10 or 11 */
2331                         return deleted_entry(oldtree, current, o);
2332                 } else if (oldtree && newtree &&
2333                          same(current, oldtree) && !same(current, newtree)) {
2334                         /* 20 or 21 */
2335                         return merged_entry(newtree, current, o);
2336                 } else
2337                         return reject_merge(current, o);
2338         }
2339         else if (newtree) {
2340                 if (oldtree && !o->initial_checkout) {
2341                         /*
2342                          * deletion of the path was staged;
2343                          */
2344                         if (same(oldtree, newtree))
2345                                 return 1;
2346                         return reject_merge(oldtree, o);
2347                 }
2348                 return merged_entry(newtree, current, o);
2349         }
2350         return deleted_entry(oldtree, current, o);
2351 }
2352
2353 /*
2354  * Bind merge.
2355  *
2356  * Keep the index entries at stage0, collapse stage1 but make sure
2357  * stage0 does not have anything there.
2358  */
2359 int bind_merge(const struct cache_entry * const *src,
2360                struct unpack_trees_options *o)
2361 {
2362         const struct cache_entry *old = src[0];
2363         const struct cache_entry *a = src[1];
2364
2365         if (o->merge_size != 1)
2366                 return error("Cannot do a bind merge of %d trees",
2367                              o->merge_size);
2368         if (a && old)
2369                 return o->gently ? -1 :
2370                         error(ERRORMSG(o, ERROR_BIND_OVERLAP),
2371                               super_prefixed(a->name),
2372                               super_prefixed(old->name));
2373         if (!a)
2374                 return keep_entry(old, o);
2375         else
2376                 return merged_entry(a, NULL, o);
2377 }
2378
2379 /*
2380  * One-way merge.
2381  *
2382  * The rule is:
2383  * - take the stat information from stage0, take the data from stage1
2384  */
2385 int oneway_merge(const struct cache_entry * const *src,
2386                  struct unpack_trees_options *o)
2387 {
2388         const struct cache_entry *old = src[0];
2389         const struct cache_entry *a = src[1];
2390
2391         if (o->merge_size != 1)
2392                 return error("Cannot do a oneway merge of %d trees",
2393                              o->merge_size);
2394
2395         if (!a || a == o->df_conflict_entry)
2396                 return deleted_entry(old, old, o);
2397
2398         if (old && same(old, a)) {
2399                 int update = 0;
2400                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
2401                         struct stat st;
2402                         if (lstat(old->name, &st) ||
2403                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
2404                                 update |= CE_UPDATE;
2405                 }
2406                 if (o->update && S_ISGITLINK(old->ce_mode) &&
2407                     should_update_submodules() && !verify_uptodate(old, o))
2408                         update |= CE_UPDATE;
2409                 add_entry(o, old, update, 0);
2410                 return 0;
2411         }
2412         return merged_entry(a, old, o);
2413 }