Merge branch 'ss/t6025-modernize'
[git] / unpack-trees.c
1 #include "cache.h"
2 #include "argv-array.h"
3 #include "repository.h"
4 #include "config.h"
5 #include "dir.h"
6 #include "tree.h"
7 #include "tree-walk.h"
8 #include "cache-tree.h"
9 #include "unpack-trees.h"
10 #include "progress.h"
11 #include "refs.h"
12 #include "attr.h"
13 #include "split-index.h"
14 #include "submodule.h"
15 #include "submodule-config.h"
16 #include "fsmonitor.h"
17 #include "object-store.h"
18 #include "promisor-remote.h"
19
20 /*
21  * Error messages expected by scripts out of plumbing commands such as
22  * read-tree.  Non-scripted Porcelain is not required to use these messages
23  * and in fact are encouraged to reword them to better suit their particular
24  * situation better.  See how "git checkout" and "git merge" replaces
25  * them using setup_unpack_trees_porcelain(), for example.
26  */
27 static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
28         /* ERROR_WOULD_OVERWRITE */
29         "Entry '%s' would be overwritten by merge. Cannot merge.",
30
31         /* ERROR_NOT_UPTODATE_FILE */
32         "Entry '%s' not uptodate. Cannot merge.",
33
34         /* ERROR_NOT_UPTODATE_DIR */
35         "Updating '%s' would lose untracked files in it",
36
37         /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
38         "Untracked working tree file '%s' would be overwritten by merge.",
39
40         /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
41         "Untracked working tree file '%s' would be removed by merge.",
42
43         /* ERROR_BIND_OVERLAP */
44         "Entry '%s' overlaps with '%s'.  Cannot bind.",
45
46         /* ERROR_SPARSE_NOT_UPTODATE_FILE */
47         "Entry '%s' not uptodate. Cannot update sparse checkout.",
48
49         /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
50         "Working tree file '%s' would be overwritten by sparse checkout update.",
51
52         /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
53         "Working tree file '%s' would be removed by sparse checkout update.",
54
55         /* ERROR_WOULD_LOSE_SUBMODULE */
56         "Submodule '%s' cannot checkout new HEAD.",
57 };
58
59 #define ERRORMSG(o,type) \
60         ( ((o) && (o)->msgs[(type)]) \
61           ? ((o)->msgs[(type)])      \
62           : (unpack_plumbing_errors[(type)]) )
63
64 static const char *super_prefixed(const char *path)
65 {
66         /*
67          * It is necessary and sufficient to have two static buffers
68          * here, as the return value of this function is fed to
69          * error() using the unpack_*_errors[] templates we see above.
70          */
71         static struct strbuf buf[2] = {STRBUF_INIT, STRBUF_INIT};
72         static int super_prefix_len = -1;
73         static unsigned idx = ARRAY_SIZE(buf) - 1;
74
75         if (super_prefix_len < 0) {
76                 const char *super_prefix = get_super_prefix();
77                 if (!super_prefix) {
78                         super_prefix_len = 0;
79                 } else {
80                         int i;
81                         for (i = 0; i < ARRAY_SIZE(buf); i++)
82                                 strbuf_addstr(&buf[i], super_prefix);
83                         super_prefix_len = buf[0].len;
84                 }
85         }
86
87         if (!super_prefix_len)
88                 return path;
89
90         if (++idx >= ARRAY_SIZE(buf))
91                 idx = 0;
92
93         strbuf_setlen(&buf[idx], super_prefix_len);
94         strbuf_addstr(&buf[idx], path);
95
96         return buf[idx].buf;
97 }
98
99 void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
100                                   const char *cmd)
101 {
102         int i;
103         const char **msgs = opts->msgs;
104         const char *msg;
105
106         argv_array_init(&opts->msgs_to_free);
107
108         if (!strcmp(cmd, "checkout"))
109                 msg = advice_commit_before_merge
110                       ? _("Your local changes to the following files would be overwritten by checkout:\n%%s"
111                           "Please commit your changes or stash them before you switch branches.")
112                       : _("Your local changes to the following files would be overwritten by checkout:\n%%s");
113         else if (!strcmp(cmd, "merge"))
114                 msg = advice_commit_before_merge
115                       ? _("Your local changes to the following files would be overwritten by merge:\n%%s"
116                           "Please commit your changes or stash them before you merge.")
117                       : _("Your local changes to the following files would be overwritten by merge:\n%%s");
118         else
119                 msg = advice_commit_before_merge
120                       ? _("Your local changes to the following files would be overwritten by %s:\n%%s"
121                           "Please commit your changes or stash them before you %s.")
122                       : _("Your local changes to the following files would be overwritten by %s:\n%%s");
123         msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
124                 argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
125
126         msgs[ERROR_NOT_UPTODATE_DIR] =
127                 _("Updating the following directories would lose untracked files in them:\n%s");
128
129         if (!strcmp(cmd, "checkout"))
130                 msg = advice_commit_before_merge
131                       ? _("The following untracked working tree files would be removed by checkout:\n%%s"
132                           "Please move or remove them before you switch branches.")
133                       : _("The following untracked working tree files would be removed by checkout:\n%%s");
134         else if (!strcmp(cmd, "merge"))
135                 msg = advice_commit_before_merge
136                       ? _("The following untracked working tree files would be removed by merge:\n%%s"
137                           "Please move or remove them before you merge.")
138                       : _("The following untracked working tree files would be removed by merge:\n%%s");
139         else
140                 msg = advice_commit_before_merge
141                       ? _("The following untracked working tree files would be removed by %s:\n%%s"
142                           "Please move or remove them before you %s.")
143                       : _("The following untracked working tree files would be removed by %s:\n%%s");
144         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] =
145                 argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
146
147         if (!strcmp(cmd, "checkout"))
148                 msg = advice_commit_before_merge
149                       ? _("The following untracked working tree files would be overwritten by checkout:\n%%s"
150                           "Please move or remove them before you switch branches.")
151                       : _("The following untracked working tree files would be overwritten by checkout:\n%%s");
152         else if (!strcmp(cmd, "merge"))
153                 msg = advice_commit_before_merge
154                       ? _("The following untracked working tree files would be overwritten by merge:\n%%s"
155                           "Please move or remove them before you merge.")
156                       : _("The following untracked working tree files would be overwritten by merge:\n%%s");
157         else
158                 msg = advice_commit_before_merge
159                       ? _("The following untracked working tree files would be overwritten by %s:\n%%s"
160                           "Please move or remove them before you %s.")
161                       : _("The following untracked working tree files would be overwritten by %s:\n%%s");
162         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] =
163                 argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
164
165         /*
166          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
167          * cannot easily display it as a list.
168          */
169         msgs[ERROR_BIND_OVERLAP] = _("Entry '%s' overlaps with '%s'.  Cannot bind.");
170
171         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
172                 _("Cannot update sparse checkout: the following entries are not up to date:\n%s");
173         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
174                 _("The following working tree files would be overwritten by sparse checkout update:\n%s");
175         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
176                 _("The following working tree files would be removed by sparse checkout update:\n%s");
177         msgs[ERROR_WOULD_LOSE_SUBMODULE] =
178                 _("Cannot update submodule:\n%s");
179
180         opts->show_all_errors = 1;
181         /* rejected paths may not have a static buffer */
182         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
183                 opts->unpack_rejects[i].strdup_strings = 1;
184 }
185
186 void clear_unpack_trees_porcelain(struct unpack_trees_options *opts)
187 {
188         argv_array_clear(&opts->msgs_to_free);
189         memset(opts->msgs, 0, sizeof(opts->msgs));
190 }
191
192 static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
193                          unsigned int set, unsigned int clear)
194 {
195         clear |= CE_HASHED;
196
197         if (set & CE_REMOVE)
198                 set |= CE_WT_REMOVE;
199
200         ce->ce_flags = (ce->ce_flags & ~clear) | set;
201         return add_index_entry(&o->result, ce,
202                                ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
203 }
204
205 static void add_entry(struct unpack_trees_options *o,
206                       const struct cache_entry *ce,
207                       unsigned int set, unsigned int clear)
208 {
209         do_add_entry(o, dup_cache_entry(ce, &o->result), set, clear);
210 }
211
212 /*
213  * add error messages on path <path>
214  * corresponding to the type <e> with the message <msg>
215  * indicating if it should be display in porcelain or not
216  */
217 static int add_rejected_path(struct unpack_trees_options *o,
218                              enum unpack_trees_error_types e,
219                              const char *path)
220 {
221         if (o->quiet)
222                 return -1;
223
224         if (!o->show_all_errors)
225                 return error(ERRORMSG(o, e), super_prefixed(path));
226
227         /*
228          * Otherwise, insert in a list for future display by
229          * display_error_msgs()
230          */
231         string_list_append(&o->unpack_rejects[e], path);
232         return -1;
233 }
234
235 /*
236  * display all the error messages stored in a nice way
237  */
238 static void display_error_msgs(struct unpack_trees_options *o)
239 {
240         int e, i;
241         int something_displayed = 0;
242         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
243                 struct string_list *rejects = &o->unpack_rejects[e];
244                 if (rejects->nr > 0) {
245                         struct strbuf path = STRBUF_INIT;
246                         something_displayed = 1;
247                         for (i = 0; i < rejects->nr; i++)
248                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
249                         error(ERRORMSG(o, e), super_prefixed(path.buf));
250                         strbuf_release(&path);
251                 }
252                 string_list_clear(rejects, 0);
253         }
254         if (something_displayed)
255                 fprintf(stderr, _("Aborting\n"));
256 }
257
258 static int check_submodule_move_head(const struct cache_entry *ce,
259                                      const char *old_id,
260                                      const char *new_id,
261                                      struct unpack_trees_options *o)
262 {
263         unsigned flags = SUBMODULE_MOVE_HEAD_DRY_RUN;
264         const struct submodule *sub = submodule_from_ce(ce);
265
266         if (!sub)
267                 return 0;
268
269         if (o->reset)
270                 flags |= SUBMODULE_MOVE_HEAD_FORCE;
271
272         if (submodule_move_head(ce->name, old_id, new_id, flags))
273                 return add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
274         return 0;
275 }
276
277 /*
278  * Perform 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  * different 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, NULL);
298                         repo_read_gitmodules(the_repository);
299                 }
300         }
301 }
302
303 static struct progress *get_progress(struct unpack_trees_options *o)
304 {
305         unsigned cnt = 0, total = 0;
306         struct index_state *index = &o->result;
307
308         if (!o->update || !o->verbose_update)
309                 return NULL;
310
311         for (; cnt < index->cache_nr; cnt++) {
312                 const struct cache_entry *ce = index->cache[cnt];
313                 if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
314                         total++;
315         }
316
317         return start_delayed_progress(_("Updating files"), total);
318 }
319
320 static void setup_collided_checkout_detection(struct checkout *state,
321                                               struct index_state *index)
322 {
323         int i;
324
325         state->clone = 1;
326         for (i = 0; i < index->cache_nr; i++)
327                 index->cache[i]->ce_flags &= ~CE_MATCHED;
328 }
329
330 static void report_collided_checkout(struct index_state *index)
331 {
332         struct string_list list = STRING_LIST_INIT_NODUP;
333         int i;
334
335         for (i = 0; i < index->cache_nr; i++) {
336                 struct cache_entry *ce = index->cache[i];
337
338                 if (!(ce->ce_flags & CE_MATCHED))
339                         continue;
340
341                 string_list_append(&list, ce->name);
342                 ce->ce_flags &= ~CE_MATCHED;
343         }
344
345         list.cmp = fspathcmp;
346         string_list_sort(&list);
347
348         if (list.nr) {
349                 warning(_("the following paths have collided (e.g. case-sensitive paths\n"
350                           "on a case-insensitive filesystem) and only one from the same\n"
351                           "colliding group is in the working tree:\n"));
352
353                 for (i = 0; i < list.nr; i++)
354                         fprintf(stderr, "  '%s'\n", list.items[i].string);
355         }
356
357         string_list_clear(&list, 0);
358 }
359
360 static int check_updates(struct unpack_trees_options *o)
361 {
362         unsigned cnt = 0;
363         int errs = 0;
364         struct progress *progress;
365         struct index_state *index = &o->result;
366         struct checkout state = CHECKOUT_INIT;
367         int i;
368
369         trace_performance_enter();
370         state.force = 1;
371         state.quiet = 1;
372         state.refresh_cache = 1;
373         state.istate = index;
374
375         if (!o->update || o->dry_run) {
376                 remove_marked_cache_entries(index, 0);
377                 trace_performance_leave("check_updates");
378                 return 0;
379         }
380
381         if (o->clone)
382                 setup_collided_checkout_detection(&state, index);
383
384         progress = get_progress(o);
385
386         git_attr_set_direction(GIT_ATTR_CHECKOUT);
387
388         if (should_update_submodules())
389                 load_gitmodules_file(index, NULL);
390
391         for (i = 0; i < index->cache_nr; i++) {
392                 const struct cache_entry *ce = index->cache[i];
393
394                 if (ce->ce_flags & CE_WT_REMOVE) {
395                         display_progress(progress, ++cnt);
396                         unlink_entry(ce);
397                 }
398         }
399
400         remove_marked_cache_entries(index, 0);
401         remove_scheduled_dirs();
402
403         if (should_update_submodules())
404                 load_gitmodules_file(index, &state);
405
406         enable_delayed_checkout(&state);
407         if (has_promisor_remote()) {
408                 /*
409                  * Prefetch the objects that are to be checked out in the loop
410                  * below.
411                  */
412                 struct oid_array to_fetch = OID_ARRAY_INIT;
413                 for (i = 0; i < index->cache_nr; i++) {
414                         struct cache_entry *ce = index->cache[i];
415
416                         if (!(ce->ce_flags & CE_UPDATE) ||
417                             S_ISGITLINK(ce->ce_mode))
418                                 continue;
419                         if (!oid_object_info_extended(the_repository, &ce->oid,
420                                                       NULL,
421                                                       OBJECT_INFO_FOR_PREFETCH))
422                                 continue;
423                         oid_array_append(&to_fetch, &ce->oid);
424                 }
425                 if (to_fetch.nr)
426                         promisor_remote_get_direct(the_repository,
427                                                    to_fetch.oid, to_fetch.nr);
428                 oid_array_clear(&to_fetch);
429         }
430         for (i = 0; i < index->cache_nr; i++) {
431                 struct cache_entry *ce = index->cache[i];
432
433                 if (ce->ce_flags & CE_UPDATE) {
434                         if (ce->ce_flags & CE_WT_REMOVE)
435                                 BUG("both update and delete flags are set on %s",
436                                     ce->name);
437                         display_progress(progress, ++cnt);
438                         ce->ce_flags &= ~CE_UPDATE;
439                         errs |= checkout_entry(ce, &state, NULL, NULL);
440                 }
441         }
442         stop_progress(&progress);
443         errs |= finish_delayed_checkout(&state, NULL);
444         git_attr_set_direction(GIT_ATTR_CHECKIN);
445
446         if (o->clone)
447                 report_collided_checkout(index);
448
449         trace_performance_leave("check_updates");
450         return errs != 0;
451 }
452
453 static int verify_uptodate_sparse(const struct cache_entry *ce,
454                                   struct unpack_trees_options *o);
455 static int verify_absent_sparse(const struct cache_entry *ce,
456                                 enum unpack_trees_error_types,
457                                 struct unpack_trees_options *o);
458
459 static int apply_sparse_checkout(struct index_state *istate,
460                                  struct cache_entry *ce,
461                                  struct unpack_trees_options *o)
462 {
463         int was_skip_worktree = ce_skip_worktree(ce);
464
465         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
466                 ce->ce_flags |= CE_SKIP_WORKTREE;
467         else
468                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
469         if (was_skip_worktree != ce_skip_worktree(ce)) {
470                 ce->ce_flags |= CE_UPDATE_IN_BASE;
471                 mark_fsmonitor_invalid(istate, ce);
472                 istate->cache_changed |= CE_ENTRY_CHANGED;
473         }
474
475         /*
476          * if (!was_skip_worktree && !ce_skip_worktree()) {
477          *      This is perfectly normal. Move on;
478          * }
479          */
480
481         /*
482          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
483          * area as a result of ce_skip_worktree() shortcuts in
484          * verify_absent() and verify_uptodate().
485          * Make sure they don't modify worktree if they are already
486          * outside checkout area
487          */
488         if (was_skip_worktree && ce_skip_worktree(ce)) {
489                 ce->ce_flags &= ~CE_UPDATE;
490
491                 /*
492                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
493                  * on to get that file removed from both index and worktree.
494                  * If that file is already outside worktree area, don't
495                  * bother remove it.
496                  */
497                 if (ce->ce_flags & CE_REMOVE)
498                         ce->ce_flags &= ~CE_WT_REMOVE;
499         }
500
501         if (!was_skip_worktree && ce_skip_worktree(ce)) {
502                 /*
503                  * If CE_UPDATE is set, verify_uptodate() must be called already
504                  * also stat info may have lost after merged_entry() so calling
505                  * verify_uptodate() again may fail
506                  */
507                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
508                         return -1;
509                 ce->ce_flags |= CE_WT_REMOVE;
510                 ce->ce_flags &= ~CE_UPDATE;
511         }
512         if (was_skip_worktree && !ce_skip_worktree(ce)) {
513                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
514                         return -1;
515                 ce->ce_flags |= CE_UPDATE;
516         }
517         return 0;
518 }
519
520 static inline int call_unpack_fn(const struct cache_entry * const *src,
521                                  struct unpack_trees_options *o)
522 {
523         int ret = o->fn(src, o);
524         if (ret > 0)
525                 ret = 0;
526         return ret;
527 }
528
529 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
530 {
531         ce->ce_flags |= CE_UNPACKED;
532
533         if (o->cache_bottom < o->src_index->cache_nr &&
534             o->src_index->cache[o->cache_bottom] == ce) {
535                 int bottom = o->cache_bottom;
536                 while (bottom < o->src_index->cache_nr &&
537                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
538                         bottom++;
539                 o->cache_bottom = bottom;
540         }
541 }
542
543 static void mark_all_ce_unused(struct index_state *index)
544 {
545         int i;
546         for (i = 0; i < index->cache_nr; i++)
547                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
548 }
549
550 static int locate_in_src_index(const struct cache_entry *ce,
551                                struct unpack_trees_options *o)
552 {
553         struct index_state *index = o->src_index;
554         int len = ce_namelen(ce);
555         int pos = index_name_pos(index, ce->name, len);
556         if (pos < 0)
557                 pos = -1 - pos;
558         return pos;
559 }
560
561 /*
562  * We call unpack_index_entry() with an unmerged cache entry
563  * only in diff-index, and it wants a single callback.  Skip
564  * the other unmerged entry with the same name.
565  */
566 static void mark_ce_used_same_name(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;
572
573         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
574                 struct cache_entry *next = index->cache[pos];
575                 if (len != ce_namelen(next) ||
576                     memcmp(ce->name, next->name, len))
577                         break;
578                 mark_ce_used(next, o);
579         }
580 }
581
582 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
583 {
584         const struct index_state *index = o->src_index;
585         int pos = o->cache_bottom;
586
587         while (pos < index->cache_nr) {
588                 struct cache_entry *ce = index->cache[pos];
589                 if (!(ce->ce_flags & CE_UNPACKED))
590                         return ce;
591                 pos++;
592         }
593         return NULL;
594 }
595
596 static void add_same_unmerged(const struct cache_entry *ce,
597                               struct unpack_trees_options *o)
598 {
599         struct index_state *index = o->src_index;
600         int len = ce_namelen(ce);
601         int pos = index_name_pos(index, ce->name, len);
602
603         if (0 <= pos)
604                 die("programming error in a caller of mark_ce_used_same_name");
605         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
606                 struct cache_entry *next = index->cache[pos];
607                 if (len != ce_namelen(next) ||
608                     memcmp(ce->name, next->name, len))
609                         break;
610                 add_entry(o, next, 0, 0);
611                 mark_ce_used(next, o);
612         }
613 }
614
615 static int unpack_index_entry(struct cache_entry *ce,
616                               struct unpack_trees_options *o)
617 {
618         const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
619         int ret;
620
621         src[0] = ce;
622
623         mark_ce_used(ce, o);
624         if (ce_stage(ce)) {
625                 if (o->skip_unmerged) {
626                         add_entry(o, ce, 0, 0);
627                         return 0;
628                 }
629         }
630         ret = call_unpack_fn(src, o);
631         if (ce_stage(ce))
632                 mark_ce_used_same_name(ce, o);
633         return ret;
634 }
635
636 static int find_cache_pos(struct traverse_info *, const char *p, size_t len);
637
638 static void restore_cache_bottom(struct traverse_info *info, int bottom)
639 {
640         struct unpack_trees_options *o = info->data;
641
642         if (o->diff_index_cached)
643                 return;
644         o->cache_bottom = bottom;
645 }
646
647 static int switch_cache_bottom(struct traverse_info *info)
648 {
649         struct unpack_trees_options *o = info->data;
650         int ret, pos;
651
652         if (o->diff_index_cached)
653                 return 0;
654         ret = o->cache_bottom;
655         pos = find_cache_pos(info->prev, info->name, info->namelen);
656
657         if (pos < -1)
658                 o->cache_bottom = -2 - pos;
659         else if (pos < 0)
660                 o->cache_bottom = o->src_index->cache_nr;
661         return ret;
662 }
663
664 static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
665 {
666         return !is_null_oid(&name_j->oid) && !is_null_oid(&name_k->oid) && oideq(&name_j->oid, &name_k->oid);
667 }
668
669 static int all_trees_same_as_cache_tree(int n, unsigned long dirmask,
670                                         struct name_entry *names,
671                                         struct traverse_info *info)
672 {
673         struct unpack_trees_options *o = info->data;
674         int i;
675
676         if (!o->merge || dirmask != ((1 << n) - 1))
677                 return 0;
678
679         for (i = 1; i < n; i++)
680                 if (!are_same_oid(names, names + i))
681                         return 0;
682
683         return cache_tree_matches_traversal(o->src_index->cache_tree, names, info);
684 }
685
686 static int index_pos_by_traverse_info(struct name_entry *names,
687                                       struct traverse_info *info)
688 {
689         struct unpack_trees_options *o = info->data;
690         struct strbuf name = STRBUF_INIT;
691         int pos;
692
693         strbuf_make_traverse_path(&name, info, names->path, names->pathlen);
694         strbuf_addch(&name, '/');
695         pos = index_name_pos(o->src_index, name.buf, name.len);
696         if (pos >= 0)
697                 BUG("This is a directory and should not exist in index");
698         pos = -pos - 1;
699         if (pos >= o->src_index->cache_nr ||
700             !starts_with(o->src_index->cache[pos]->name, name.buf) ||
701             (pos > 0 && starts_with(o->src_index->cache[pos-1]->name, name.buf)))
702                 BUG("pos %d doesn't point to the first entry of %s in index",
703                     pos, name.buf);
704         strbuf_release(&name);
705         return pos;
706 }
707
708 /*
709  * Fast path if we detect that all trees are the same as cache-tree at this
710  * path. We'll walk these trees in an iterative loop using cache-tree/index
711  * instead of ODB since we already know what these trees contain.
712  */
713 static int traverse_by_cache_tree(int pos, int nr_entries, int nr_names,
714                                   struct traverse_info *info)
715 {
716         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
717         struct unpack_trees_options *o = info->data;
718         struct cache_entry *tree_ce = NULL;
719         int ce_len = 0;
720         int i, d;
721
722         if (!o->merge)
723                 BUG("We need cache-tree to do this optimization");
724
725         /*
726          * Do what unpack_callback() and unpack_nondirectories() normally
727          * do. But we walk all paths in an iterative loop instead.
728          *
729          * D/F conflicts and higher stage entries are not a concern
730          * because cache-tree would be invalidated and we would never
731          * get here in the first place.
732          */
733         for (i = 0; i < nr_entries; i++) {
734                 int new_ce_len, len, rc;
735
736                 src[0] = o->src_index->cache[pos + i];
737
738                 len = ce_namelen(src[0]);
739                 new_ce_len = cache_entry_size(len);
740
741                 if (new_ce_len > ce_len) {
742                         new_ce_len <<= 1;
743                         tree_ce = xrealloc(tree_ce, new_ce_len);
744                         memset(tree_ce, 0, new_ce_len);
745                         ce_len = new_ce_len;
746
747                         tree_ce->ce_flags = create_ce_flags(0);
748
749                         for (d = 1; d <= nr_names; d++)
750                                 src[d] = tree_ce;
751                 }
752
753                 tree_ce->ce_mode = src[0]->ce_mode;
754                 tree_ce->ce_namelen = len;
755                 oidcpy(&tree_ce->oid, &src[0]->oid);
756                 memcpy(tree_ce->name, src[0]->name, len + 1);
757
758                 rc = call_unpack_fn((const struct cache_entry * const *)src, o);
759                 if (rc < 0) {
760                         free(tree_ce);
761                         return rc;
762                 }
763
764                 mark_ce_used(src[0], o);
765         }
766         free(tree_ce);
767         if (o->debug_unpack)
768                 printf("Unpacked %d entries from %s to %s using cache-tree\n",
769                        nr_entries,
770                        o->src_index->cache[pos]->name,
771                        o->src_index->cache[pos + nr_entries - 1]->name);
772         return 0;
773 }
774
775 static int traverse_trees_recursive(int n, unsigned long dirmask,
776                                     unsigned long df_conflicts,
777                                     struct name_entry *names,
778                                     struct traverse_info *info)
779 {
780         struct unpack_trees_options *o = info->data;
781         int i, ret, bottom;
782         int nr_buf = 0;
783         struct tree_desc t[MAX_UNPACK_TREES];
784         void *buf[MAX_UNPACK_TREES];
785         struct traverse_info newinfo;
786         struct name_entry *p;
787         int nr_entries;
788
789         nr_entries = all_trees_same_as_cache_tree(n, dirmask, names, info);
790         if (nr_entries > 0) {
791                 int pos = index_pos_by_traverse_info(names, info);
792
793                 if (!o->merge || df_conflicts)
794                         BUG("Wrong condition to get here buddy");
795
796                 /*
797                  * All entries up to 'pos' must have been processed
798                  * (i.e. marked CE_UNPACKED) at this point. But to be safe,
799                  * save and restore cache_bottom anyway to not miss
800                  * unprocessed entries before 'pos'.
801                  */
802                 bottom = o->cache_bottom;
803                 ret = traverse_by_cache_tree(pos, nr_entries, n, info);
804                 o->cache_bottom = bottom;
805                 return ret;
806         }
807
808         p = names;
809         while (!p->mode)
810                 p++;
811
812         newinfo = *info;
813         newinfo.prev = info;
814         newinfo.pathspec = info->pathspec;
815         newinfo.name = p->path;
816         newinfo.namelen = p->pathlen;
817         newinfo.mode = p->mode;
818         newinfo.pathlen = st_add3(newinfo.pathlen, tree_entry_len(p), 1);
819         newinfo.df_conflicts |= df_conflicts;
820
821         /*
822          * Fetch the tree from the ODB for each peer directory in the
823          * n commits.
824          *
825          * For 2- and 3-way traversals, we try to avoid hitting the
826          * ODB twice for the same OID.  This should yield a nice speed
827          * up in checkouts and merges when the commits are similar.
828          *
829          * We don't bother doing the full O(n^2) search for larger n,
830          * because wider traversals don't happen that often and we
831          * avoid the search setup.
832          *
833          * When 2 peer OIDs are the same, we just copy the tree
834          * descriptor data.  This implicitly borrows the buffer
835          * data from the earlier cell.
836          */
837         for (i = 0; i < n; i++, dirmask >>= 1) {
838                 if (i > 0 && are_same_oid(&names[i], &names[i - 1]))
839                         t[i] = t[i - 1];
840                 else if (i > 1 && are_same_oid(&names[i], &names[i - 2]))
841                         t[i] = t[i - 2];
842                 else {
843                         const struct object_id *oid = NULL;
844                         if (dirmask & 1)
845                                 oid = &names[i].oid;
846                         buf[nr_buf++] = fill_tree_descriptor(the_repository, t + i, oid);
847                 }
848         }
849
850         bottom = switch_cache_bottom(&newinfo);
851         ret = traverse_trees(o->src_index, n, t, &newinfo);
852         restore_cache_bottom(&newinfo, bottom);
853
854         for (i = 0; i < nr_buf; i++)
855                 free(buf[i]);
856
857         return ret;
858 }
859
860 /*
861  * Compare the traverse-path to the cache entry without actually
862  * having to generate the textual representation of the traverse
863  * path.
864  *
865  * NOTE! This *only* compares up to the size of the traverse path
866  * itself - the caller needs to do the final check for the cache
867  * entry having more data at the end!
868  */
869 static int do_compare_entry_piecewise(const struct cache_entry *ce,
870                                       const struct traverse_info *info,
871                                       const char *name, size_t namelen,
872                                       unsigned mode)
873 {
874         int pathlen, ce_len;
875         const char *ce_name;
876
877         if (info->prev) {
878                 int cmp = do_compare_entry_piecewise(ce, info->prev,
879                                                      info->name, info->namelen,
880                                                      info->mode);
881                 if (cmp)
882                         return cmp;
883         }
884         pathlen = info->pathlen;
885         ce_len = ce_namelen(ce);
886
887         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
888         if (ce_len < pathlen)
889                 return -1;
890
891         ce_len -= pathlen;
892         ce_name = ce->name + pathlen;
893
894         return df_name_compare(ce_name, ce_len, S_IFREG, name, namelen, mode);
895 }
896
897 static int do_compare_entry(const struct cache_entry *ce,
898                             const struct traverse_info *info,
899                             const char *name, size_t namelen,
900                             unsigned mode)
901 {
902         int pathlen, ce_len;
903         const char *ce_name;
904         int cmp;
905
906         /*
907          * If we have not precomputed the traverse path, it is quicker
908          * to avoid doing so.  But if we have precomputed it,
909          * it is quicker to use the precomputed version.
910          */
911         if (!info->traverse_path)
912                 return do_compare_entry_piecewise(ce, info, name, namelen, mode);
913
914         cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
915         if (cmp)
916                 return cmp;
917
918         pathlen = info->pathlen;
919         ce_len = ce_namelen(ce);
920
921         if (ce_len < pathlen)
922                 return -1;
923
924         ce_len -= pathlen;
925         ce_name = ce->name + pathlen;
926
927         return df_name_compare(ce_name, ce_len, S_IFREG, name, namelen, mode);
928 }
929
930 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
931 {
932         int cmp = do_compare_entry(ce, info, n->path, n->pathlen, n->mode);
933         if (cmp)
934                 return cmp;
935
936         /*
937          * Even if the beginning compared identically, the ce should
938          * compare as bigger than a directory leading up to it!
939          */
940         return ce_namelen(ce) > traverse_path_len(info, tree_entry_len(n));
941 }
942
943 static int ce_in_traverse_path(const struct cache_entry *ce,
944                                const struct traverse_info *info)
945 {
946         if (!info->prev)
947                 return 1;
948         if (do_compare_entry(ce, info->prev,
949                              info->name, info->namelen, info->mode))
950                 return 0;
951         /*
952          * If ce (blob) is the same name as the path (which is a tree
953          * we will be descending into), it won't be inside it.
954          */
955         return (info->pathlen < ce_namelen(ce));
956 }
957
958 static struct cache_entry *create_ce_entry(const struct traverse_info *info,
959         const struct name_entry *n,
960         int stage,
961         struct index_state *istate,
962         int is_transient)
963 {
964         size_t len = traverse_path_len(info, tree_entry_len(n));
965         struct cache_entry *ce =
966                 is_transient ?
967                 make_empty_transient_cache_entry(len) :
968                 make_empty_cache_entry(istate, len);
969
970         ce->ce_mode = create_ce_mode(n->mode);
971         ce->ce_flags = create_ce_flags(stage);
972         ce->ce_namelen = len;
973         oidcpy(&ce->oid, &n->oid);
974         /* len+1 because the cache_entry allocates space for NUL */
975         make_traverse_path(ce->name, len + 1, info, n->path, n->pathlen);
976
977         return ce;
978 }
979
980 /*
981  * Note that traverse_by_cache_tree() duplicates some logic in this function
982  * without actually calling it. If you change the logic here you may need to
983  * check and change there as well.
984  */
985 static int unpack_nondirectories(int n, unsigned long mask,
986                                  unsigned long dirmask,
987                                  struct cache_entry **src,
988                                  const struct name_entry *names,
989                                  const struct traverse_info *info)
990 {
991         int i;
992         struct unpack_trees_options *o = info->data;
993         unsigned long conflicts = info->df_conflicts | dirmask;
994
995         /* Do we have *only* directories? Nothing to do */
996         if (mask == dirmask && !src[0])
997                 return 0;
998
999         /*
1000          * Ok, we've filled in up to any potential index entry in src[0],
1001          * now do the rest.
1002          */
1003         for (i = 0; i < n; i++) {
1004                 int stage;
1005                 unsigned int bit = 1ul << i;
1006                 if (conflicts & bit) {
1007                         src[i + o->merge] = o->df_conflict_entry;
1008                         continue;
1009                 }
1010                 if (!(mask & bit))
1011                         continue;
1012                 if (!o->merge)
1013                         stage = 0;
1014                 else if (i + 1 < o->head_idx)
1015                         stage = 1;
1016                 else if (i + 1 > o->head_idx)
1017                         stage = 3;
1018                 else
1019                         stage = 2;
1020
1021                 /*
1022                  * If the merge bit is set, then the cache entries are
1023                  * discarded in the following block.  In this case,
1024                  * construct "transient" cache_entries, as they are
1025                  * not stored in the index.  otherwise construct the
1026                  * cache entry from the index aware logic.
1027                  */
1028                 src[i + o->merge] = create_ce_entry(info, names + i, stage, &o->result, o->merge);
1029         }
1030
1031         if (o->merge) {
1032                 int rc = call_unpack_fn((const struct cache_entry * const *)src,
1033                                         o);
1034                 for (i = 0; i < n; i++) {
1035                         struct cache_entry *ce = src[i + o->merge];
1036                         if (ce != o->df_conflict_entry)
1037                                 discard_cache_entry(ce);
1038                 }
1039                 return rc;
1040         }
1041
1042         for (i = 0; i < n; i++)
1043                 if (src[i] && src[i] != o->df_conflict_entry)
1044                         if (do_add_entry(o, src[i], 0, 0))
1045                                 return -1;
1046
1047         return 0;
1048 }
1049
1050 static int unpack_failed(struct unpack_trees_options *o, const char *message)
1051 {
1052         discard_index(&o->result);
1053         if (!o->quiet && !o->exiting_early) {
1054                 if (message)
1055                         return error("%s", message);
1056                 return -1;
1057         }
1058         return -1;
1059 }
1060
1061 /*
1062  * The tree traversal is looking at name p.  If we have a matching entry,
1063  * return it.  If name p is a directory in the index, do not return
1064  * anything, as we will want to match it when the traversal descends into
1065  * the directory.
1066  */
1067 static int find_cache_pos(struct traverse_info *info,
1068                           const char *p, size_t p_len)
1069 {
1070         int pos;
1071         struct unpack_trees_options *o = info->data;
1072         struct index_state *index = o->src_index;
1073         int pfxlen = info->pathlen;
1074
1075         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
1076                 const struct cache_entry *ce = index->cache[pos];
1077                 const char *ce_name, *ce_slash;
1078                 int cmp, ce_len;
1079
1080                 if (ce->ce_flags & CE_UNPACKED) {
1081                         /*
1082                          * cache_bottom entry is already unpacked, so
1083                          * we can never match it; don't check it
1084                          * again.
1085                          */
1086                         if (pos == o->cache_bottom)
1087                                 ++o->cache_bottom;
1088                         continue;
1089                 }
1090                 if (!ce_in_traverse_path(ce, info)) {
1091                         /*
1092                          * Check if we can skip future cache checks
1093                          * (because we're already past all possible
1094                          * entries in the traverse path).
1095                          */
1096                         if (info->traverse_path) {
1097                                 if (strncmp(ce->name, info->traverse_path,
1098                                             info->pathlen) > 0)
1099                                         break;
1100                         }
1101                         continue;
1102                 }
1103                 ce_name = ce->name + pfxlen;
1104                 ce_slash = strchr(ce_name, '/');
1105                 if (ce_slash)
1106                         ce_len = ce_slash - ce_name;
1107                 else
1108                         ce_len = ce_namelen(ce) - pfxlen;
1109                 cmp = name_compare(p, p_len, ce_name, ce_len);
1110                 /*
1111                  * Exact match; if we have a directory we need to
1112                  * delay returning it.
1113                  */
1114                 if (!cmp)
1115                         return ce_slash ? -2 - pos : pos;
1116                 if (0 < cmp)
1117                         continue; /* keep looking */
1118                 /*
1119                  * ce_name sorts after p->path; could it be that we
1120                  * have files under p->path directory in the index?
1121                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
1122                  * have "t/a" in the index.
1123                  */
1124                 if (p_len < ce_len && !memcmp(ce_name, p, p_len) &&
1125                     ce_name[p_len] < '/')
1126                         continue; /* keep looking */
1127                 break;
1128         }
1129         return -1;
1130 }
1131
1132 static struct cache_entry *find_cache_entry(struct traverse_info *info,
1133                                             const struct name_entry *p)
1134 {
1135         int pos = find_cache_pos(info, p->path, p->pathlen);
1136         struct unpack_trees_options *o = info->data;
1137
1138         if (0 <= pos)
1139                 return o->src_index->cache[pos];
1140         else
1141                 return NULL;
1142 }
1143
1144 static void debug_path(struct traverse_info *info)
1145 {
1146         if (info->prev) {
1147                 debug_path(info->prev);
1148                 if (*info->prev->name)
1149                         putchar('/');
1150         }
1151         printf("%s", info->name);
1152 }
1153
1154 static void debug_name_entry(int i, struct name_entry *n)
1155 {
1156         printf("ent#%d %06o %s\n", i,
1157                n->path ? n->mode : 0,
1158                n->path ? n->path : "(missing)");
1159 }
1160
1161 static void debug_unpack_callback(int n,
1162                                   unsigned long mask,
1163                                   unsigned long dirmask,
1164                                   struct name_entry *names,
1165                                   struct traverse_info *info)
1166 {
1167         int i;
1168         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
1169                mask, dirmask, n);
1170         debug_path(info);
1171         putchar('\n');
1172         for (i = 0; i < n; i++)
1173                 debug_name_entry(i, names + i);
1174 }
1175
1176 /*
1177  * Note that traverse_by_cache_tree() duplicates some logic in this function
1178  * without actually calling it. If you change the logic here you may need to
1179  * check and change there as well.
1180  */
1181 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
1182 {
1183         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
1184         struct unpack_trees_options *o = info->data;
1185         const struct name_entry *p = names;
1186
1187         /* Find first entry with a real name (we could use "mask" too) */
1188         while (!p->mode)
1189                 p++;
1190
1191         if (o->debug_unpack)
1192                 debug_unpack_callback(n, mask, dirmask, names, info);
1193
1194         /* Are we supposed to look at the index too? */
1195         if (o->merge) {
1196                 while (1) {
1197                         int cmp;
1198                         struct cache_entry *ce;
1199
1200                         if (o->diff_index_cached)
1201                                 ce = next_cache_entry(o);
1202                         else
1203                                 ce = find_cache_entry(info, p);
1204
1205                         if (!ce)
1206                                 break;
1207                         cmp = compare_entry(ce, info, p);
1208                         if (cmp < 0) {
1209                                 if (unpack_index_entry(ce, o) < 0)
1210                                         return unpack_failed(o, NULL);
1211                                 continue;
1212                         }
1213                         if (!cmp) {
1214                                 if (ce_stage(ce)) {
1215                                         /*
1216                                          * If we skip unmerged index
1217                                          * entries, we'll skip this
1218                                          * entry *and* the tree
1219                                          * entries associated with it!
1220                                          */
1221                                         if (o->skip_unmerged) {
1222                                                 add_same_unmerged(ce, o);
1223                                                 return mask;
1224                                         }
1225                                 }
1226                                 src[0] = ce;
1227                         }
1228                         break;
1229                 }
1230         }
1231
1232         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
1233                 return -1;
1234
1235         if (o->merge && src[0]) {
1236                 if (ce_stage(src[0]))
1237                         mark_ce_used_same_name(src[0], o);
1238                 else
1239                         mark_ce_used(src[0], o);
1240         }
1241
1242         /* Now handle any directories.. */
1243         if (dirmask) {
1244                 /* special case: "diff-index --cached" looking at a tree */
1245                 if (o->diff_index_cached &&
1246                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
1247                         int matches;
1248                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
1249                                                                names, info);
1250                         /*
1251                          * Everything under the name matches; skip the
1252                          * entire hierarchy.  diff_index_cached codepath
1253                          * special cases D/F conflicts in such a way that
1254                          * it does not do any look-ahead, so this is safe.
1255                          */
1256                         if (matches) {
1257                                 o->cache_bottom += matches;
1258                                 return mask;
1259                         }
1260                 }
1261
1262                 if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
1263                                              names, info) < 0)
1264                         return -1;
1265                 return mask;
1266         }
1267
1268         return mask;
1269 }
1270
1271 static int clear_ce_flags_1(struct index_state *istate,
1272                             struct cache_entry **cache, int nr,
1273                             struct strbuf *prefix,
1274                             int select_mask, int clear_mask,
1275                             struct pattern_list *pl,
1276                             enum pattern_match_result default_match,
1277                             int progress_nr);
1278
1279 /* Whole directory matching */
1280 static int clear_ce_flags_dir(struct index_state *istate,
1281                               struct cache_entry **cache, int nr,
1282                               struct strbuf *prefix,
1283                               char *basename,
1284                               int select_mask, int clear_mask,
1285                               struct pattern_list *pl,
1286                               enum pattern_match_result default_match,
1287                               int progress_nr)
1288 {
1289         struct cache_entry **cache_end;
1290         int dtype = DT_DIR;
1291         int rc;
1292         enum pattern_match_result ret, orig_ret;
1293         orig_ret = path_matches_pattern_list(prefix->buf, prefix->len,
1294                                              basename, &dtype, pl, istate);
1295
1296         strbuf_addch(prefix, '/');
1297
1298         /* If undecided, use matching result of parent dir in defval */
1299         if (orig_ret == UNDECIDED)
1300                 ret = default_match;
1301         else
1302                 ret = orig_ret;
1303
1304         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
1305                 struct cache_entry *ce = *cache_end;
1306                 if (strncmp(ce->name, prefix->buf, prefix->len))
1307                         break;
1308         }
1309
1310         if (pl->use_cone_patterns && orig_ret == MATCHED_RECURSIVE) {
1311                 struct cache_entry **ce = cache;
1312                 rc = cache_end - cache;
1313
1314                 while (ce < cache_end) {
1315                         (*ce)->ce_flags &= ~clear_mask;
1316                         ce++;
1317                 }
1318         } else if (pl->use_cone_patterns && orig_ret == NOT_MATCHED) {
1319                 rc = cache_end - cache;
1320         } else {
1321                 rc = clear_ce_flags_1(istate, cache, cache_end - cache,
1322                                       prefix,
1323                                       select_mask, clear_mask,
1324                                       pl, ret,
1325                                       progress_nr);
1326         }
1327
1328         strbuf_setlen(prefix, prefix->len - 1);
1329         return rc;
1330 }
1331
1332 /*
1333  * Traverse the index, find every entry that matches according to
1334  * o->pl. Do "ce_flags &= ~clear_mask" on those entries. Return the
1335  * number of traversed entries.
1336  *
1337  * If select_mask is non-zero, only entries whose ce_flags has on of
1338  * those bits enabled are traversed.
1339  *
1340  * cache        : pointer to an index entry
1341  * prefix_len   : an offset to its path
1342  *
1343  * The current path ("prefix") including the trailing '/' is
1344  *   cache[0]->name[0..(prefix_len-1)]
1345  * Top level path has prefix_len zero.
1346  */
1347 static int clear_ce_flags_1(struct index_state *istate,
1348                             struct cache_entry **cache, int nr,
1349                             struct strbuf *prefix,
1350                             int select_mask, int clear_mask,
1351                             struct pattern_list *pl,
1352                             enum pattern_match_result default_match,
1353                             int progress_nr)
1354 {
1355         struct cache_entry **cache_end = cache + nr;
1356
1357         /*
1358          * Process all entries that have the given prefix and meet
1359          * select_mask condition
1360          */
1361         while(cache != cache_end) {
1362                 struct cache_entry *ce = *cache;
1363                 const char *name, *slash;
1364                 int len, dtype;
1365                 enum pattern_match_result ret;
1366
1367                 display_progress(istate->progress, progress_nr);
1368
1369                 if (select_mask && !(ce->ce_flags & select_mask)) {
1370                         cache++;
1371                         progress_nr++;
1372                         continue;
1373                 }
1374
1375                 if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
1376                         break;
1377
1378                 name = ce->name + prefix->len;
1379                 slash = strchr(name, '/');
1380
1381                 /* If it's a directory, try whole directory match first */
1382                 if (slash) {
1383                         int processed;
1384
1385                         len = slash - name;
1386                         strbuf_add(prefix, name, len);
1387
1388                         processed = clear_ce_flags_dir(istate, cache, cache_end - cache,
1389                                                        prefix,
1390                                                        prefix->buf + prefix->len - len,
1391                                                        select_mask, clear_mask,
1392                                                        pl, default_match,
1393                                                        progress_nr);
1394
1395                         /* clear_c_f_dir eats a whole dir already? */
1396                         if (processed) {
1397                                 cache += processed;
1398                                 progress_nr += processed;
1399                                 strbuf_setlen(prefix, prefix->len - len);
1400                                 continue;
1401                         }
1402
1403                         strbuf_addch(prefix, '/');
1404                         processed = clear_ce_flags_1(istate, cache, cache_end - cache,
1405                                                      prefix,
1406                                                      select_mask, clear_mask, pl,
1407                                                      default_match, progress_nr);
1408
1409                         cache += processed;
1410                         progress_nr += processed;
1411
1412                         strbuf_setlen(prefix, prefix->len - len - 1);
1413                         continue;
1414                 }
1415
1416                 /* Non-directory */
1417                 dtype = ce_to_dtype(ce);
1418                 ret = path_matches_pattern_list(ce->name,
1419                                                 ce_namelen(ce),
1420                                                 name, &dtype, pl, istate);
1421                 if (ret == UNDECIDED)
1422                         ret = default_match;
1423                 if (ret == MATCHED)
1424                         ce->ce_flags &= ~clear_mask;
1425                 cache++;
1426                 progress_nr++;
1427         }
1428
1429         display_progress(istate->progress, progress_nr);
1430         return nr - (cache_end - cache);
1431 }
1432
1433 static int clear_ce_flags(struct index_state *istate,
1434                           int select_mask, int clear_mask,
1435                           struct pattern_list *pl,
1436                           int show_progress)
1437 {
1438         static struct strbuf prefix = STRBUF_INIT;
1439         char label[100];
1440         int rval;
1441
1442         strbuf_reset(&prefix);
1443         if (show_progress)
1444                 istate->progress = start_delayed_progress(
1445                                         _("Updating index flags"),
1446                                         istate->cache_nr);
1447
1448         xsnprintf(label, sizeof(label), "clear_ce_flags(0x%08lx,0x%08lx)",
1449                   (unsigned long)select_mask, (unsigned long)clear_mask);
1450         trace2_region_enter("unpack_trees", label, the_repository);
1451         rval = clear_ce_flags_1(istate,
1452                                 istate->cache,
1453                                 istate->cache_nr,
1454                                 &prefix,
1455                                 select_mask, clear_mask,
1456                                 pl, 0, 0);
1457         trace2_region_leave("unpack_trees", label, the_repository);
1458
1459         stop_progress(&istate->progress);
1460         return rval;
1461 }
1462
1463 /*
1464  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1465  */
1466 static void mark_new_skip_worktree(struct pattern_list *pl,
1467                                    struct index_state *istate,
1468                                    int select_flag, int skip_wt_flag,
1469                                    int show_progress)
1470 {
1471         int i;
1472
1473         /*
1474          * 1. Pretend the narrowest worktree: only unmerged entries
1475          * are checked out
1476          */
1477         for (i = 0; i < istate->cache_nr; i++) {
1478                 struct cache_entry *ce = istate->cache[i];
1479
1480                 if (select_flag && !(ce->ce_flags & select_flag))
1481                         continue;
1482
1483                 if (!ce_stage(ce) && !(ce->ce_flags & CE_CONFLICTED))
1484                         ce->ce_flags |= skip_wt_flag;
1485                 else
1486                         ce->ce_flags &= ~skip_wt_flag;
1487         }
1488
1489         /*
1490          * 2. Widen worktree according to sparse-checkout file.
1491          * Matched entries will have skip_wt_flag cleared (i.e. "in")
1492          */
1493         clear_ce_flags(istate, select_flag, skip_wt_flag, pl, show_progress);
1494 }
1495
1496 static int verify_absent(const struct cache_entry *,
1497                          enum unpack_trees_error_types,
1498                          struct unpack_trees_options *);
1499 /*
1500  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1501  * resulting index, -2 on failure to reflect the changes to the work tree.
1502  *
1503  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1504  */
1505 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1506 {
1507         int i, ret;
1508         static struct cache_entry *dfc;
1509         struct pattern_list pl;
1510
1511         if (len > MAX_UNPACK_TREES)
1512                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1513
1514         trace_performance_enter();
1515         memset(&pl, 0, sizeof(pl));
1516         if (!core_apply_sparse_checkout || !o->update)
1517                 o->skip_sparse_checkout = 1;
1518         if (!o->skip_sparse_checkout && !o->pl) {
1519                 char *sparse = git_pathdup("info/sparse-checkout");
1520                 pl.use_cone_patterns = core_sparse_checkout_cone;
1521                 if (add_patterns_from_file_to_list(sparse, "", 0, &pl, NULL) < 0)
1522                         o->skip_sparse_checkout = 1;
1523                 else
1524                         o->pl = &pl;
1525                 free(sparse);
1526         }
1527
1528         memset(&o->result, 0, sizeof(o->result));
1529         o->result.initialized = 1;
1530         o->result.timestamp.sec = o->src_index->timestamp.sec;
1531         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1532         o->result.version = o->src_index->version;
1533         if (!o->src_index->split_index) {
1534                 o->result.split_index = NULL;
1535         } else if (o->src_index == o->dst_index) {
1536                 /*
1537                  * o->dst_index (and thus o->src_index) will be discarded
1538                  * and overwritten with o->result at the end of this function,
1539                  * so just use src_index's split_index to avoid having to
1540                  * create a new one.
1541                  */
1542                 o->result.split_index = o->src_index->split_index;
1543                 o->result.split_index->refcount++;
1544         } else {
1545                 o->result.split_index = init_split_index(&o->result);
1546         }
1547         oidcpy(&o->result.oid, &o->src_index->oid);
1548         o->merge_size = len;
1549         mark_all_ce_unused(o->src_index);
1550
1551         if (o->src_index->fsmonitor_last_update)
1552                 o->result.fsmonitor_last_update = o->src_index->fsmonitor_last_update;
1553
1554         /*
1555          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1556          */
1557         if (!o->skip_sparse_checkout)
1558                 mark_new_skip_worktree(o->pl, o->src_index, 0,
1559                                        CE_NEW_SKIP_WORKTREE, o->verbose_update);
1560
1561         if (!dfc)
1562                 dfc = xcalloc(1, cache_entry_size(0));
1563         o->df_conflict_entry = dfc;
1564
1565         if (len) {
1566                 const char *prefix = o->prefix ? o->prefix : "";
1567                 struct traverse_info info;
1568
1569                 setup_traverse_info(&info, prefix);
1570                 info.fn = unpack_callback;
1571                 info.data = o;
1572                 info.show_all_errors = o->show_all_errors;
1573                 info.pathspec = o->pathspec;
1574
1575                 if (o->prefix) {
1576                         /*
1577                          * Unpack existing index entries that sort before the
1578                          * prefix the tree is spliced into.  Note that o->merge
1579                          * is always true in this case.
1580                          */
1581                         while (1) {
1582                                 struct cache_entry *ce = next_cache_entry(o);
1583                                 if (!ce)
1584                                         break;
1585                                 if (ce_in_traverse_path(ce, &info))
1586                                         break;
1587                                 if (unpack_index_entry(ce, o) < 0)
1588                                         goto return_failed;
1589                         }
1590                 }
1591
1592                 trace_performance_enter();
1593                 ret = traverse_trees(o->src_index, len, t, &info);
1594                 trace_performance_leave("traverse_trees");
1595                 if (ret < 0)
1596                         goto return_failed;
1597         }
1598
1599         /* Any left-over entries in the index? */
1600         if (o->merge) {
1601                 while (1) {
1602                         struct cache_entry *ce = next_cache_entry(o);
1603                         if (!ce)
1604                                 break;
1605                         if (unpack_index_entry(ce, o) < 0)
1606                                 goto return_failed;
1607                 }
1608         }
1609         mark_all_ce_unused(o->src_index);
1610
1611         if (o->trivial_merges_only && o->nontrivial_merge) {
1612                 ret = unpack_failed(o, "Merge requires file-level merging");
1613                 goto done;
1614         }
1615
1616         if (!o->skip_sparse_checkout) {
1617                 int empty_worktree = 1;
1618
1619                 /*
1620                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1621                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1622                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1623                  */
1624                 mark_new_skip_worktree(o->pl, &o->result,
1625                                        CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE,
1626                                        o->verbose_update);
1627
1628                 ret = 0;
1629                 for (i = 0; i < o->result.cache_nr; i++) {
1630                         struct cache_entry *ce = o->result.cache[i];
1631
1632                         /*
1633                          * Entries marked with CE_ADDED in merged_entry() do not have
1634                          * verify_absent() check (the check is effectively disabled
1635                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1636                          *
1637                          * Do the real check now because we have had
1638                          * correct CE_NEW_SKIP_WORKTREE
1639                          */
1640                         if (ce->ce_flags & CE_ADDED &&
1641                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1642                                 if (!o->show_all_errors)
1643                                         goto return_failed;
1644                                 ret = -1;
1645                         }
1646
1647                         if (apply_sparse_checkout(&o->result, ce, o)) {
1648                                 if (!o->show_all_errors)
1649                                         goto return_failed;
1650                                 ret = -1;
1651                         }
1652                         if (!ce_skip_worktree(ce))
1653                                 empty_worktree = 0;
1654
1655                 }
1656                 if (ret < 0)
1657                         goto return_failed;
1658                 /*
1659                  * Sparse checkout is meant to narrow down checkout area
1660                  * but it does not make sense to narrow down to empty working
1661                  * tree. This is usually a mistake in sparse checkout rules.
1662                  * Do not allow users to do that.
1663                  */
1664                 if (o->result.cache_nr && empty_worktree) {
1665                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1666                         goto done;
1667                 }
1668         }
1669
1670         ret = check_updates(o) ? (-2) : 0;
1671         if (o->dst_index) {
1672                 move_index_extensions(&o->result, o->src_index);
1673                 if (!ret) {
1674                         if (git_env_bool("GIT_TEST_CHECK_CACHE_TREE", 0))
1675                                 cache_tree_verify(the_repository, &o->result);
1676                         if (!o->result.cache_tree)
1677                                 o->result.cache_tree = cache_tree();
1678                         if (!cache_tree_fully_valid(o->result.cache_tree))
1679                                 cache_tree_update(&o->result,
1680                                                   WRITE_TREE_SILENT |
1681                                                   WRITE_TREE_REPAIR);
1682                 }
1683
1684                 o->result.updated_workdir = 1;
1685                 discard_index(o->dst_index);
1686                 *o->dst_index = o->result;
1687         } else {
1688                 discard_index(&o->result);
1689         }
1690         o->src_index = NULL;
1691
1692 done:
1693         trace_performance_leave("unpack_trees");
1694         if (!o->keep_pattern_list)
1695                 clear_pattern_list(&pl);
1696         return ret;
1697
1698 return_failed:
1699         if (o->show_all_errors)
1700                 display_error_msgs(o);
1701         mark_all_ce_unused(o->src_index);
1702         ret = unpack_failed(o, NULL);
1703         if (o->exiting_early)
1704                 ret = 0;
1705         goto done;
1706 }
1707
1708 /* Here come the merge functions */
1709
1710 static int reject_merge(const struct cache_entry *ce,
1711                         struct unpack_trees_options *o)
1712 {
1713         return add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1714 }
1715
1716 static int same(const struct cache_entry *a, const struct cache_entry *b)
1717 {
1718         if (!!a != !!b)
1719                 return 0;
1720         if (!a && !b)
1721                 return 1;
1722         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1723                 return 0;
1724         return a->ce_mode == b->ce_mode &&
1725                oideq(&a->oid, &b->oid);
1726 }
1727
1728
1729 /*
1730  * When a CE gets turned into an unmerged entry, we
1731  * want it to be up-to-date
1732  */
1733 static int verify_uptodate_1(const struct cache_entry *ce,
1734                              struct unpack_trees_options *o,
1735                              enum unpack_trees_error_types error_type)
1736 {
1737         struct stat st;
1738
1739         if (o->index_only)
1740                 return 0;
1741
1742         /*
1743          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1744          * if this entry is truly up-to-date because this file may be
1745          * overwritten.
1746          */
1747         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1748                 ; /* keep checking */
1749         else if (o->reset || ce_uptodate(ce))
1750                 return 0;
1751
1752         if (!lstat(ce->name, &st)) {
1753                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1754                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1755
1756                 if (submodule_from_ce(ce)) {
1757                         int r = check_submodule_move_head(ce,
1758                                 "HEAD", oid_to_hex(&ce->oid), o);
1759                         if (r)
1760                                 return add_rejected_path(o, error_type, ce->name);
1761                         return 0;
1762                 }
1763
1764                 if (!changed)
1765                         return 0;
1766                 /*
1767                  * Historic default policy was to allow submodule to be out
1768                  * of sync wrt the superproject index. If the submodule was
1769                  * not considered interesting above, we don't care here.
1770                  */
1771                 if (S_ISGITLINK(ce->ce_mode))
1772                         return 0;
1773
1774                 errno = 0;
1775         }
1776         if (errno == ENOENT)
1777                 return 0;
1778         return add_rejected_path(o, error_type, ce->name);
1779 }
1780
1781 int verify_uptodate(const struct cache_entry *ce,
1782                     struct unpack_trees_options *o)
1783 {
1784         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1785                 return 0;
1786         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1787 }
1788
1789 static int verify_uptodate_sparse(const struct cache_entry *ce,
1790                                   struct unpack_trees_options *o)
1791 {
1792         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1793 }
1794
1795 /*
1796  * TODO: We should actually invalidate o->result, not src_index [1].
1797  * But since cache tree and untracked cache both are not copied to
1798  * o->result until unpacking is complete, we invalidate them on
1799  * src_index instead with the assumption that they will be copied to
1800  * dst_index at the end.
1801  *
1802  * [1] src_index->cache_tree is also used in unpack_callback() so if
1803  * we invalidate o->result, we need to update it to use
1804  * o->result.cache_tree as well.
1805  */
1806 static void invalidate_ce_path(const struct cache_entry *ce,
1807                                struct unpack_trees_options *o)
1808 {
1809         if (!ce)
1810                 return;
1811         cache_tree_invalidate_path(o->src_index, ce->name);
1812         untracked_cache_invalidate_path(o->src_index, ce->name, 1);
1813 }
1814
1815 /*
1816  * Check that checking out ce->sha1 in subdir ce->name is not
1817  * going to overwrite any working files.
1818  *
1819  * Currently, git does not checkout subprojects during a superproject
1820  * checkout, so it is not going to overwrite anything.
1821  */
1822 static int verify_clean_submodule(const char *old_sha1,
1823                                   const struct cache_entry *ce,
1824                                   struct unpack_trees_options *o)
1825 {
1826         if (!submodule_from_ce(ce))
1827                 return 0;
1828
1829         return check_submodule_move_head(ce, old_sha1,
1830                                          oid_to_hex(&ce->oid), o);
1831 }
1832
1833 static int verify_clean_subdirectory(const struct cache_entry *ce,
1834                                      struct unpack_trees_options *o)
1835 {
1836         /*
1837          * we are about to extract "ce->name"; we would not want to lose
1838          * anything in the existing directory there.
1839          */
1840         int namelen;
1841         int i;
1842         struct dir_struct d;
1843         char *pathbuf;
1844         int cnt = 0;
1845
1846         if (S_ISGITLINK(ce->ce_mode)) {
1847                 struct object_id oid;
1848                 int sub_head = resolve_gitlink_ref(ce->name, "HEAD", &oid);
1849                 /*
1850                  * If we are not going to update the submodule, then
1851                  * we don't care.
1852                  */
1853                 if (!sub_head && oideq(&oid, &ce->oid))
1854                         return 0;
1855                 return verify_clean_submodule(sub_head ? NULL : oid_to_hex(&oid),
1856                                               ce, o);
1857         }
1858
1859         /*
1860          * First let's make sure we do not have a local modification
1861          * in that directory.
1862          */
1863         namelen = ce_namelen(ce);
1864         for (i = locate_in_src_index(ce, o);
1865              i < o->src_index->cache_nr;
1866              i++) {
1867                 struct cache_entry *ce2 = o->src_index->cache[i];
1868                 int len = ce_namelen(ce2);
1869                 if (len < namelen ||
1870                     strncmp(ce->name, ce2->name, namelen) ||
1871                     ce2->name[namelen] != '/')
1872                         break;
1873                 /*
1874                  * ce2->name is an entry in the subdirectory to be
1875                  * removed.
1876                  */
1877                 if (!ce_stage(ce2)) {
1878                         if (verify_uptodate(ce2, o))
1879                                 return -1;
1880                         add_entry(o, ce2, CE_REMOVE, 0);
1881                         invalidate_ce_path(ce, o);
1882                         mark_ce_used(ce2, o);
1883                 }
1884                 cnt++;
1885         }
1886
1887         /*
1888          * Then we need to make sure that we do not lose a locally
1889          * present file that is not ignored.
1890          */
1891         pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1892
1893         memset(&d, 0, sizeof(d));
1894         if (o->dir)
1895                 d.exclude_per_dir = o->dir->exclude_per_dir;
1896         i = read_directory(&d, o->src_index, pathbuf, namelen+1, NULL);
1897         if (i)
1898                 return add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1899         free(pathbuf);
1900         return cnt;
1901 }
1902
1903 /*
1904  * This gets called when there was no index entry for the tree entry 'dst',
1905  * but we found a file in the working tree that 'lstat()' said was fine,
1906  * and we're on a case-insensitive filesystem.
1907  *
1908  * See if we can find a case-insensitive match in the index that also
1909  * matches the stat information, and assume it's that other file!
1910  */
1911 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1912 {
1913         const struct cache_entry *src;
1914
1915         src = index_file_exists(o->src_index, name, len, 1);
1916         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1917 }
1918
1919 static int check_ok_to_remove(const char *name, int len, int dtype,
1920                               const struct cache_entry *ce, struct stat *st,
1921                               enum unpack_trees_error_types error_type,
1922                               struct unpack_trees_options *o)
1923 {
1924         const struct cache_entry *result;
1925
1926         /*
1927          * It may be that the 'lstat()' succeeded even though
1928          * target 'ce' was absent, because there is an old
1929          * entry that is different only in case..
1930          *
1931          * Ignore that lstat() if it matches.
1932          */
1933         if (ignore_case && icase_exists(o, name, len, st))
1934                 return 0;
1935
1936         if (o->dir &&
1937             is_excluded(o->dir, o->src_index, name, &dtype))
1938                 /*
1939                  * ce->name is explicitly excluded, so it is Ok to
1940                  * overwrite it.
1941                  */
1942                 return 0;
1943         if (S_ISDIR(st->st_mode)) {
1944                 /*
1945                  * We are checking out path "foo" and
1946                  * found "foo/." in the working tree.
1947                  * This is tricky -- if we have modified
1948                  * files that are in "foo/" we would lose
1949                  * them.
1950                  */
1951                 if (verify_clean_subdirectory(ce, o) < 0)
1952                         return -1;
1953                 return 0;
1954         }
1955
1956         /*
1957          * The previous round may already have decided to
1958          * delete this path, which is in a subdirectory that
1959          * is being replaced with a blob.
1960          */
1961         result = index_file_exists(&o->result, name, len, 0);
1962         if (result) {
1963                 if (result->ce_flags & CE_REMOVE)
1964                         return 0;
1965         }
1966
1967         return add_rejected_path(o, error_type, name);
1968 }
1969
1970 /*
1971  * We do not want to remove or overwrite a working tree file that
1972  * is not tracked, unless it is ignored.
1973  */
1974 static int verify_absent_1(const struct cache_entry *ce,
1975                            enum unpack_trees_error_types error_type,
1976                            struct unpack_trees_options *o)
1977 {
1978         int len;
1979         struct stat st;
1980
1981         if (o->index_only || o->reset || !o->update)
1982                 return 0;
1983
1984         len = check_leading_path(ce->name, ce_namelen(ce));
1985         if (!len)
1986                 return 0;
1987         else if (len > 0) {
1988                 char *path;
1989                 int ret;
1990
1991                 path = xmemdupz(ce->name, len);
1992                 if (lstat(path, &st))
1993                         ret = error_errno("cannot stat '%s'", path);
1994                 else {
1995                         if (submodule_from_ce(ce))
1996                                 ret = check_submodule_move_head(ce,
1997                                                                 oid_to_hex(&ce->oid),
1998                                                                 NULL, o);
1999                         else
2000                                 ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
2001                                                          &st, error_type, o);
2002                 }
2003                 free(path);
2004                 return ret;
2005         } else if (lstat(ce->name, &st)) {
2006                 if (errno != ENOENT)
2007                         return error_errno("cannot stat '%s'", ce->name);
2008                 return 0;
2009         } else {
2010                 if (submodule_from_ce(ce))
2011                         return check_submodule_move_head(ce, oid_to_hex(&ce->oid),
2012                                                          NULL, o);
2013
2014                 return check_ok_to_remove(ce->name, ce_namelen(ce),
2015                                           ce_to_dtype(ce), ce, &st,
2016                                           error_type, o);
2017         }
2018 }
2019
2020 static int verify_absent(const struct cache_entry *ce,
2021                          enum unpack_trees_error_types error_type,
2022                          struct unpack_trees_options *o)
2023 {
2024         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
2025                 return 0;
2026         return verify_absent_1(ce, error_type, o);
2027 }
2028
2029 static int verify_absent_sparse(const struct cache_entry *ce,
2030                                 enum unpack_trees_error_types error_type,
2031                                 struct unpack_trees_options *o)
2032 {
2033         enum unpack_trees_error_types orphaned_error = error_type;
2034         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
2035                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
2036
2037         return verify_absent_1(ce, orphaned_error, o);
2038 }
2039
2040 static int merged_entry(const struct cache_entry *ce,
2041                         const struct cache_entry *old,
2042                         struct unpack_trees_options *o)
2043 {
2044         int update = CE_UPDATE;
2045         struct cache_entry *merge = dup_cache_entry(ce, &o->result);
2046
2047         if (!old) {
2048                 /*
2049                  * New index entries. In sparse checkout, the following
2050                  * verify_absent() will be delayed until after
2051                  * traverse_trees() finishes in unpack_trees(), then:
2052                  *
2053                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
2054                  *  - verify_absent() be called again, this time with
2055                  *    correct CE_NEW_SKIP_WORKTREE
2056                  *
2057                  * verify_absent() call here does nothing in sparse
2058                  * checkout (i.e. o->skip_sparse_checkout == 0)
2059                  */
2060                 update |= CE_ADDED;
2061                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
2062
2063                 if (verify_absent(merge,
2064                                   ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
2065                         discard_cache_entry(merge);
2066                         return -1;
2067                 }
2068                 invalidate_ce_path(merge, o);
2069
2070                 if (submodule_from_ce(ce)) {
2071                         int ret = check_submodule_move_head(ce, NULL,
2072                                                             oid_to_hex(&ce->oid),
2073                                                             o);
2074                         if (ret)
2075                                 return ret;
2076                 }
2077
2078         } else if (!(old->ce_flags & CE_CONFLICTED)) {
2079                 /*
2080                  * See if we can re-use the old CE directly?
2081                  * That way we get the uptodate stat info.
2082                  *
2083                  * This also removes the UPDATE flag on a match; otherwise
2084                  * we will end up overwriting local changes in the work tree.
2085                  */
2086                 if (same(old, merge)) {
2087                         copy_cache_entry(merge, old);
2088                         update = 0;
2089                 } else {
2090                         if (verify_uptodate(old, o)) {
2091                                 discard_cache_entry(merge);
2092                                 return -1;
2093                         }
2094                         /* Migrate old flags over */
2095                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
2096                         invalidate_ce_path(old, o);
2097                 }
2098
2099                 if (submodule_from_ce(ce)) {
2100                         int ret = check_submodule_move_head(ce, oid_to_hex(&old->oid),
2101                                                             oid_to_hex(&ce->oid),
2102                                                             o);
2103                         if (ret)
2104                                 return ret;
2105                 }
2106         } else {
2107                 /*
2108                  * Previously unmerged entry left as an existence
2109                  * marker by read_index_unmerged();
2110                  */
2111                 invalidate_ce_path(old, o);
2112         }
2113
2114         if (do_add_entry(o, merge, update, CE_STAGEMASK) < 0)
2115                 return -1;
2116         return 1;
2117 }
2118
2119 static int deleted_entry(const struct cache_entry *ce,
2120                          const struct cache_entry *old,
2121                          struct unpack_trees_options *o)
2122 {
2123         /* Did it exist in the index? */
2124         if (!old) {
2125                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
2126                         return -1;
2127                 return 0;
2128         }
2129         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
2130                 return -1;
2131         add_entry(o, ce, CE_REMOVE, 0);
2132         invalidate_ce_path(ce, o);
2133         return 1;
2134 }
2135
2136 static int keep_entry(const struct cache_entry *ce,
2137                       struct unpack_trees_options *o)
2138 {
2139         add_entry(o, ce, 0, 0);
2140         if (ce_stage(ce))
2141                 invalidate_ce_path(ce, o);
2142         return 1;
2143 }
2144
2145 #if DBRT_DEBUG
2146 static void show_stage_entry(FILE *o,
2147                              const char *label, const struct cache_entry *ce)
2148 {
2149         if (!ce)
2150                 fprintf(o, "%s (missing)\n", label);
2151         else
2152                 fprintf(o, "%s%06o %s %d\t%s\n",
2153                         label,
2154                         ce->ce_mode,
2155                         oid_to_hex(&ce->oid),
2156                         ce_stage(ce),
2157                         ce->name);
2158 }
2159 #endif
2160
2161 int threeway_merge(const struct cache_entry * const *stages,
2162                    struct unpack_trees_options *o)
2163 {
2164         const struct cache_entry *index;
2165         const struct cache_entry *head;
2166         const struct cache_entry *remote = stages[o->head_idx + 1];
2167         int count;
2168         int head_match = 0;
2169         int remote_match = 0;
2170
2171         int df_conflict_head = 0;
2172         int df_conflict_remote = 0;
2173
2174         int any_anc_missing = 0;
2175         int no_anc_exists = 1;
2176         int i;
2177
2178         for (i = 1; i < o->head_idx; i++) {
2179                 if (!stages[i] || stages[i] == o->df_conflict_entry)
2180                         any_anc_missing = 1;
2181                 else
2182                         no_anc_exists = 0;
2183         }
2184
2185         index = stages[0];
2186         head = stages[o->head_idx];
2187
2188         if (head == o->df_conflict_entry) {
2189                 df_conflict_head = 1;
2190                 head = NULL;
2191         }
2192
2193         if (remote == o->df_conflict_entry) {
2194                 df_conflict_remote = 1;
2195                 remote = NULL;
2196         }
2197
2198         /*
2199          * First, if there's a #16 situation, note that to prevent #13
2200          * and #14.
2201          */
2202         if (!same(remote, head)) {
2203                 for (i = 1; i < o->head_idx; i++) {
2204                         if (same(stages[i], head)) {
2205                                 head_match = i;
2206                         }
2207                         if (same(stages[i], remote)) {
2208                                 remote_match = i;
2209                         }
2210                 }
2211         }
2212
2213         /*
2214          * We start with cases where the index is allowed to match
2215          * something other than the head: #14(ALT) and #2ALT, where it
2216          * is permitted to match the result instead.
2217          */
2218         /* #14, #14ALT, #2ALT */
2219         if (remote && !df_conflict_head && head_match && !remote_match) {
2220                 if (index && !same(index, remote) && !same(index, head))
2221                         return reject_merge(index, o);
2222                 return merged_entry(remote, index, o);
2223         }
2224         /*
2225          * If we have an entry in the index cache, then we want to
2226          * make sure that it matches head.
2227          */
2228         if (index && !same(index, head))
2229                 return reject_merge(index, o);
2230
2231         if (head) {
2232                 /* #5ALT, #15 */
2233                 if (same(head, remote))
2234                         return merged_entry(head, index, o);
2235                 /* #13, #3ALT */
2236                 if (!df_conflict_remote && remote_match && !head_match)
2237                         return merged_entry(head, index, o);
2238         }
2239
2240         /* #1 */
2241         if (!head && !remote && any_anc_missing)
2242                 return 0;
2243
2244         /*
2245          * Under the "aggressive" rule, we resolve mostly trivial
2246          * cases that we historically had git-merge-one-file resolve.
2247          */
2248         if (o->aggressive) {
2249                 int head_deleted = !head;
2250                 int remote_deleted = !remote;
2251                 const struct cache_entry *ce = NULL;
2252
2253                 if (index)
2254                         ce = index;
2255                 else if (head)
2256                         ce = head;
2257                 else if (remote)
2258                         ce = remote;
2259                 else {
2260                         for (i = 1; i < o->head_idx; i++) {
2261                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
2262                                         ce = stages[i];
2263                                         break;
2264                                 }
2265                         }
2266                 }
2267
2268                 /*
2269                  * Deleted in both.
2270                  * Deleted in one and unchanged in the other.
2271                  */
2272                 if ((head_deleted && remote_deleted) ||
2273                     (head_deleted && remote && remote_match) ||
2274                     (remote_deleted && head && head_match)) {
2275                         if (index)
2276                                 return deleted_entry(index, index, o);
2277                         if (ce && !head_deleted) {
2278                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
2279                                         return -1;
2280                         }
2281                         return 0;
2282                 }
2283                 /*
2284                  * Added in both, identically.
2285                  */
2286                 if (no_anc_exists && head && remote && same(head, remote))
2287                         return merged_entry(head, index, o);
2288
2289         }
2290
2291         /* Below are "no merge" cases, which require that the index be
2292          * up-to-date to avoid the files getting overwritten with
2293          * conflict resolution files.
2294          */
2295         if (index) {
2296                 if (verify_uptodate(index, o))
2297                         return -1;
2298         }
2299
2300         o->nontrivial_merge = 1;
2301
2302         /* #2, #3, #4, #6, #7, #9, #10, #11. */
2303         count = 0;
2304         if (!head_match || !remote_match) {
2305                 for (i = 1; i < o->head_idx; i++) {
2306                         if (stages[i] && stages[i] != o->df_conflict_entry) {
2307                                 keep_entry(stages[i], o);
2308                                 count++;
2309                                 break;
2310                         }
2311                 }
2312         }
2313 #if DBRT_DEBUG
2314         else {
2315                 fprintf(stderr, "read-tree: warning #16 detected\n");
2316                 show_stage_entry(stderr, "head   ", stages[head_match]);
2317                 show_stage_entry(stderr, "remote ", stages[remote_match]);
2318         }
2319 #endif
2320         if (head) { count += keep_entry(head, o); }
2321         if (remote) { count += keep_entry(remote, o); }
2322         return count;
2323 }
2324
2325 /*
2326  * Two-way merge.
2327  *
2328  * The rule is to "carry forward" what is in the index without losing
2329  * information across a "fast-forward", favoring a successful merge
2330  * over a merge failure when it makes sense.  For details of the
2331  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
2332  *
2333  */
2334 int twoway_merge(const struct cache_entry * const *src,
2335                  struct unpack_trees_options *o)
2336 {
2337         const struct cache_entry *current = src[0];
2338         const struct cache_entry *oldtree = src[1];
2339         const struct cache_entry *newtree = src[2];
2340
2341         if (o->merge_size != 2)
2342                 return error("Cannot do a twoway merge of %d trees",
2343                              o->merge_size);
2344
2345         if (oldtree == o->df_conflict_entry)
2346                 oldtree = NULL;
2347         if (newtree == o->df_conflict_entry)
2348                 newtree = NULL;
2349
2350         if (current) {
2351                 if (current->ce_flags & CE_CONFLICTED) {
2352                         if (same(oldtree, newtree) || o->reset) {
2353                                 if (!newtree)
2354                                         return deleted_entry(current, current, o);
2355                                 else
2356                                         return merged_entry(newtree, current, o);
2357                         }
2358                         return reject_merge(current, o);
2359                 } else if ((!oldtree && !newtree) || /* 4 and 5 */
2360                          (!oldtree && newtree &&
2361                           same(current, newtree)) || /* 6 and 7 */
2362                          (oldtree && newtree &&
2363                           same(oldtree, newtree)) || /* 14 and 15 */
2364                          (oldtree && newtree &&
2365                           !same(oldtree, newtree) && /* 18 and 19 */
2366                           same(current, newtree))) {
2367                         return keep_entry(current, o);
2368                 } else if (oldtree && !newtree && same(current, oldtree)) {
2369                         /* 10 or 11 */
2370                         return deleted_entry(oldtree, current, o);
2371                 } else if (oldtree && newtree &&
2372                          same(current, oldtree) && !same(current, newtree)) {
2373                         /* 20 or 21 */
2374                         return merged_entry(newtree, current, o);
2375                 } else
2376                         return reject_merge(current, o);
2377         }
2378         else if (newtree) {
2379                 if (oldtree && !o->initial_checkout) {
2380                         /*
2381                          * deletion of the path was staged;
2382                          */
2383                         if (same(oldtree, newtree))
2384                                 return 1;
2385                         return reject_merge(oldtree, o);
2386                 }
2387                 return merged_entry(newtree, current, o);
2388         }
2389         return deleted_entry(oldtree, current, o);
2390 }
2391
2392 /*
2393  * Bind merge.
2394  *
2395  * Keep the index entries at stage0, collapse stage1 but make sure
2396  * stage0 does not have anything there.
2397  */
2398 int bind_merge(const struct cache_entry * const *src,
2399                struct unpack_trees_options *o)
2400 {
2401         const struct cache_entry *old = src[0];
2402         const struct cache_entry *a = src[1];
2403
2404         if (o->merge_size != 1)
2405                 return error("Cannot do a bind merge of %d trees",
2406                              o->merge_size);
2407         if (a && old)
2408                 return o->quiet ? -1 :
2409                         error(ERRORMSG(o, ERROR_BIND_OVERLAP),
2410                               super_prefixed(a->name),
2411                               super_prefixed(old->name));
2412         if (!a)
2413                 return keep_entry(old, o);
2414         else
2415                 return merged_entry(a, NULL, o);
2416 }
2417
2418 /*
2419  * One-way merge.
2420  *
2421  * The rule is:
2422  * - take the stat information from stage0, take the data from stage1
2423  */
2424 int oneway_merge(const struct cache_entry * const *src,
2425                  struct unpack_trees_options *o)
2426 {
2427         const struct cache_entry *old = src[0];
2428         const struct cache_entry *a = src[1];
2429
2430         if (o->merge_size != 1)
2431                 return error("Cannot do a oneway merge of %d trees",
2432                              o->merge_size);
2433
2434         if (!a || a == o->df_conflict_entry)
2435                 return deleted_entry(old, old, o);
2436
2437         if (old && same(old, a)) {
2438                 int update = 0;
2439                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old) &&
2440                         !(old->ce_flags & CE_FSMONITOR_VALID)) {
2441                         struct stat st;
2442                         if (lstat(old->name, &st) ||
2443                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
2444                                 update |= CE_UPDATE;
2445                 }
2446                 if (o->update && S_ISGITLINK(old->ce_mode) &&
2447                     should_update_submodules() && !verify_uptodate(old, o))
2448                         update |= CE_UPDATE;
2449                 add_entry(o, old, update, CE_STAGEMASK);
2450                 return 0;
2451         }
2452         return merged_entry(a, old, o);
2453 }