Merge branch 'cs/pretty-formats-doc-typofix'
[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 "dir.h"
15 #include "submodule.h"
16 #include "submodule-config.h"
17 #include "fsmonitor.h"
18 #include "object-store.h"
19 #include "promisor-remote.h"
20
21 /*
22  * Error messages expected by scripts out of plumbing commands such as
23  * read-tree.  Non-scripted Porcelain is not required to use these messages
24  * and in fact are encouraged to reword them to better suit their particular
25  * situation better.  See how "git checkout" and "git merge" replaces
26  * them using setup_unpack_trees_porcelain(), for example.
27  */
28 static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
29         /* ERROR_WOULD_OVERWRITE */
30         "Entry '%s' would be overwritten by merge. Cannot merge.",
31
32         /* ERROR_NOT_UPTODATE_FILE */
33         "Entry '%s' not uptodate. Cannot merge.",
34
35         /* ERROR_NOT_UPTODATE_DIR */
36         "Updating '%s' would lose untracked files in it",
37
38         /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
39         "Untracked working tree file '%s' would be overwritten by merge.",
40
41         /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
42         "Untracked working tree file '%s' would be removed by merge.",
43
44         /* ERROR_BIND_OVERLAP */
45         "Entry '%s' overlaps with '%s'.  Cannot bind.",
46
47         /* ERROR_SPARSE_NOT_UPTODATE_FILE */
48         "Entry '%s' not uptodate. Cannot update sparse checkout.",
49
50         /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
51         "Working tree file '%s' would be overwritten by sparse checkout update.",
52
53         /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
54         "Working tree file '%s' would be removed by sparse checkout update.",
55
56         /* ERROR_WOULD_LOSE_SUBMODULE */
57         "Submodule '%s' cannot checkout new HEAD.",
58 };
59
60 #define ERRORMSG(o,type) \
61         ( ((o) && (o)->msgs[(type)]) \
62           ? ((o)->msgs[(type)])      \
63           : (unpack_plumbing_errors[(type)]) )
64
65 static const char *super_prefixed(const char *path)
66 {
67         /*
68          * It is necessary and sufficient to have two static buffers
69          * here, as the return value of this function is fed to
70          * error() using the unpack_*_errors[] templates we see above.
71          */
72         static struct strbuf buf[2] = {STRBUF_INIT, STRBUF_INIT};
73         static int super_prefix_len = -1;
74         static unsigned idx = ARRAY_SIZE(buf) - 1;
75
76         if (super_prefix_len < 0) {
77                 const char *super_prefix = get_super_prefix();
78                 if (!super_prefix) {
79                         super_prefix_len = 0;
80                 } else {
81                         int i;
82                         for (i = 0; i < ARRAY_SIZE(buf); i++)
83                                 strbuf_addstr(&buf[i], super_prefix);
84                         super_prefix_len = buf[0].len;
85                 }
86         }
87
88         if (!super_prefix_len)
89                 return path;
90
91         if (++idx >= ARRAY_SIZE(buf))
92                 idx = 0;
93
94         strbuf_setlen(&buf[idx], super_prefix_len);
95         strbuf_addstr(&buf[idx], path);
96
97         return buf[idx].buf;
98 }
99
100 void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
101                                   const char *cmd)
102 {
103         int i;
104         const char **msgs = opts->msgs;
105         const char *msg;
106
107         argv_array_init(&opts->msgs_to_free);
108
109         if (!strcmp(cmd, "checkout"))
110                 msg = advice_commit_before_merge
111                       ? _("Your local changes to the following files would be overwritten by checkout:\n%%s"
112                           "Please commit your changes or stash them before you switch branches.")
113                       : _("Your local changes to the following files would be overwritten by checkout:\n%%s");
114         else if (!strcmp(cmd, "merge"))
115                 msg = advice_commit_before_merge
116                       ? _("Your local changes to the following files would be overwritten by merge:\n%%s"
117                           "Please commit your changes or stash them before you merge.")
118                       : _("Your local changes to the following files would be overwritten by merge:\n%%s");
119         else
120                 msg = advice_commit_before_merge
121                       ? _("Your local changes to the following files would be overwritten by %s:\n%%s"
122                           "Please commit your changes or stash them before you %s.")
123                       : _("Your local changes to the following files would be overwritten by %s:\n%%s");
124         msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
125                 argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
126
127         msgs[ERROR_NOT_UPTODATE_DIR] =
128                 _("Updating the following directories would lose untracked files in them:\n%s");
129
130         if (!strcmp(cmd, "checkout"))
131                 msg = advice_commit_before_merge
132                       ? _("The following untracked working tree files would be removed by checkout:\n%%s"
133                           "Please move or remove them before you switch branches.")
134                       : _("The following untracked working tree files would be removed by checkout:\n%%s");
135         else if (!strcmp(cmd, "merge"))
136                 msg = advice_commit_before_merge
137                       ? _("The following untracked working tree files would be removed by merge:\n%%s"
138                           "Please move or remove them before you merge.")
139                       : _("The following untracked working tree files would be removed by merge:\n%%s");
140         else
141                 msg = advice_commit_before_merge
142                       ? _("The following untracked working tree files would be removed by %s:\n%%s"
143                           "Please move or remove them before you %s.")
144                       : _("The following untracked working tree files would be removed by %s:\n%%s");
145         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] =
146                 argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
147
148         if (!strcmp(cmd, "checkout"))
149                 msg = advice_commit_before_merge
150                       ? _("The following untracked working tree files would be overwritten by checkout:\n%%s"
151                           "Please move or remove them before you switch branches.")
152                       : _("The following untracked working tree files would be overwritten by checkout:\n%%s");
153         else if (!strcmp(cmd, "merge"))
154                 msg = advice_commit_before_merge
155                       ? _("The following untracked working tree files would be overwritten by merge:\n%%s"
156                           "Please move or remove them before you merge.")
157                       : _("The following untracked working tree files would be overwritten by merge:\n%%s");
158         else
159                 msg = advice_commit_before_merge
160                       ? _("The following untracked working tree files would be overwritten by %s:\n%%s"
161                           "Please move or remove them before you %s.")
162                       : _("The following untracked working tree files would be overwritten by %s:\n%%s");
163         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] =
164                 argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
165
166         /*
167          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
168          * cannot easily display it as a list.
169          */
170         msgs[ERROR_BIND_OVERLAP] = _("Entry '%s' overlaps with '%s'.  Cannot bind.");
171
172         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
173                 _("Cannot update sparse checkout: the following entries are not up to date:\n%s");
174         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
175                 _("The following working tree files would be overwritten by sparse checkout update:\n%s");
176         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
177                 _("The following working tree files would be removed by sparse checkout update:\n%s");
178         msgs[ERROR_WOULD_LOSE_SUBMODULE] =
179                 _("Cannot update submodule:\n%s");
180
181         opts->show_all_errors = 1;
182         /* rejected paths may not have a static buffer */
183         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
184                 opts->unpack_rejects[i].strdup_strings = 1;
185 }
186
187 void clear_unpack_trees_porcelain(struct unpack_trees_options *opts)
188 {
189         argv_array_clear(&opts->msgs_to_free);
190         memset(opts->msgs, 0, sizeof(opts->msgs));
191 }
192
193 static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
194                          unsigned int set, unsigned int clear)
195 {
196         clear |= CE_HASHED;
197
198         if (set & CE_REMOVE)
199                 set |= CE_WT_REMOVE;
200
201         ce->ce_flags = (ce->ce_flags & ~clear) | set;
202         return add_index_entry(&o->result, ce,
203                                ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
204 }
205
206 static void add_entry(struct unpack_trees_options *o,
207                       const struct cache_entry *ce,
208                       unsigned int set, unsigned int clear)
209 {
210         do_add_entry(o, dup_cache_entry(ce, &o->result), set, clear);
211 }
212
213 /*
214  * add error messages on path <path>
215  * corresponding to the type <e> with the message <msg>
216  * indicating if it should be display in porcelain or not
217  */
218 static int add_rejected_path(struct unpack_trees_options *o,
219                              enum unpack_trees_error_types e,
220                              const char *path)
221 {
222         if (o->quiet)
223                 return -1;
224
225         if (!o->show_all_errors)
226                 return error(ERRORMSG(o, e), super_prefixed(path));
227
228         /*
229          * Otherwise, insert in a list for future display by
230          * display_error_msgs()
231          */
232         string_list_append(&o->unpack_rejects[e], path);
233         return -1;
234 }
235
236 /*
237  * display all the error messages stored in a nice way
238  */
239 static void display_error_msgs(struct unpack_trees_options *o)
240 {
241         int e, i;
242         int something_displayed = 0;
243         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
244                 struct string_list *rejects = &o->unpack_rejects[e];
245                 if (rejects->nr > 0) {
246                         struct strbuf path = STRBUF_INIT;
247                         something_displayed = 1;
248                         for (i = 0; i < rejects->nr; i++)
249                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
250                         error(ERRORMSG(o, e), super_prefixed(path.buf));
251                         strbuf_release(&path);
252                 }
253                 string_list_clear(rejects, 0);
254         }
255         if (something_displayed)
256                 fprintf(stderr, _("Aborting\n"));
257 }
258
259 static int check_submodule_move_head(const struct cache_entry *ce,
260                                      const char *old_id,
261                                      const char *new_id,
262                                      struct unpack_trees_options *o)
263 {
264         unsigned flags = SUBMODULE_MOVE_HEAD_DRY_RUN;
265         const struct submodule *sub = submodule_from_ce(ce);
266
267         if (!sub)
268                 return 0;
269
270         if (o->reset)
271                 flags |= SUBMODULE_MOVE_HEAD_FORCE;
272
273         if (submodule_move_head(ce->name, old_id, new_id, flags))
274                 return add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
275         return 0;
276 }
277
278 /*
279  * Preform the loading of the repository's gitmodules file.  This function is
280  * used by 'check_update()' to perform loading of the gitmodules file in two
281  * differnt situations:
282  * (1) before removing entries from the working tree if the gitmodules file has
283  *     been marked for removal.  This situation is specified by 'state' == NULL.
284  * (2) before checking out entries to the working tree if the gitmodules file
285  *     has been marked for update.  This situation is specified by 'state' != NULL.
286  */
287 static void load_gitmodules_file(struct index_state *index,
288                                  struct checkout *state)
289 {
290         int pos = index_name_pos(index, GITMODULES_FILE, strlen(GITMODULES_FILE));
291
292         if (pos >= 0) {
293                 struct cache_entry *ce = index->cache[pos];
294                 if (!state && ce->ce_flags & CE_WT_REMOVE) {
295                         repo_read_gitmodules(the_repository);
296                 } else if (state && (ce->ce_flags & CE_UPDATE)) {
297                         submodule_free(the_repository);
298                         checkout_entry(ce, state, NULL, NULL);
299                         repo_read_gitmodules(the_repository);
300                 }
301         }
302 }
303
304 static struct progress *get_progress(struct unpack_trees_options *o)
305 {
306         unsigned cnt = 0, total = 0;
307         struct index_state *index = &o->result;
308
309         if (!o->update || !o->verbose_update)
310                 return NULL;
311
312         for (; cnt < index->cache_nr; cnt++) {
313                 const struct cache_entry *ce = index->cache[cnt];
314                 if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
315                         total++;
316         }
317
318         return start_delayed_progress(_("Updating files"), total);
319 }
320
321 static void setup_collided_checkout_detection(struct checkout *state,
322                                               struct index_state *index)
323 {
324         int i;
325
326         state->clone = 1;
327         for (i = 0; i < index->cache_nr; i++)
328                 index->cache[i]->ce_flags &= ~CE_MATCHED;
329 }
330
331 static void report_collided_checkout(struct index_state *index)
332 {
333         struct string_list list = STRING_LIST_INIT_NODUP;
334         int i;
335
336         for (i = 0; i < index->cache_nr; i++) {
337                 struct cache_entry *ce = index->cache[i];
338
339                 if (!(ce->ce_flags & CE_MATCHED))
340                         continue;
341
342                 string_list_append(&list, ce->name);
343                 ce->ce_flags &= ~CE_MATCHED;
344         }
345
346         list.cmp = fspathcmp;
347         string_list_sort(&list);
348
349         if (list.nr) {
350                 warning(_("the following paths have collided (e.g. case-sensitive paths\n"
351                           "on a case-insensitive filesystem) and only one from the same\n"
352                           "colliding group is in the working tree:\n"));
353
354                 for (i = 0; i < list.nr; i++)
355                         fprintf(stderr, "  '%s'\n", list.items[i].string);
356         }
357
358         string_list_clear(&list, 0);
359 }
360
361 static int check_updates(struct unpack_trees_options *o)
362 {
363         unsigned cnt = 0;
364         int errs = 0;
365         struct progress *progress;
366         struct index_state *index = &o->result;
367         struct checkout state = CHECKOUT_INIT;
368         int i;
369
370         trace_performance_enter();
371         state.force = 1;
372         state.quiet = 1;
373         state.refresh_cache = 1;
374         state.istate = index;
375
376         if (o->clone)
377                 setup_collided_checkout_detection(&state, index);
378
379         progress = get_progress(o);
380
381         if (o->update)
382                 git_attr_set_direction(GIT_ATTR_CHECKOUT);
383
384         if (should_update_submodules() && o->update && !o->dry_run)
385                 load_gitmodules_file(index, NULL);
386
387         for (i = 0; i < index->cache_nr; i++) {
388                 const struct cache_entry *ce = index->cache[i];
389
390                 if (ce->ce_flags & CE_WT_REMOVE) {
391                         display_progress(progress, ++cnt);
392                         if (o->update && !o->dry_run)
393                                 unlink_entry(ce);
394                 }
395         }
396         remove_marked_cache_entries(index, 0);
397         remove_scheduled_dirs();
398
399         if (should_update_submodules() && o->update && !o->dry_run)
400                 load_gitmodules_file(index, &state);
401
402         enable_delayed_checkout(&state);
403         if (has_promisor_remote() && o->update && !o->dry_run) {
404                 /*
405                  * Prefetch the objects that are to be checked out in the loop
406                  * below.
407                  */
408                 struct oid_array to_fetch = OID_ARRAY_INIT;
409                 for (i = 0; i < index->cache_nr; i++) {
410                         struct cache_entry *ce = index->cache[i];
411
412                         if (!(ce->ce_flags & CE_UPDATE) ||
413                             S_ISGITLINK(ce->ce_mode))
414                                 continue;
415                         if (!oid_object_info_extended(the_repository, &ce->oid,
416                                                       NULL,
417                                                       OBJECT_INFO_FOR_PREFETCH))
418                                 continue;
419                         oid_array_append(&to_fetch, &ce->oid);
420                 }
421                 if (to_fetch.nr)
422                         promisor_remote_get_direct(the_repository,
423                                                    to_fetch.oid, to_fetch.nr);
424                 oid_array_clear(&to_fetch);
425         }
426         for (i = 0; i < index->cache_nr; i++) {
427                 struct cache_entry *ce = index->cache[i];
428
429                 if (ce->ce_flags & CE_UPDATE) {
430                         if (ce->ce_flags & CE_WT_REMOVE)
431                                 BUG("both update and delete flags are set on %s",
432                                     ce->name);
433                         display_progress(progress, ++cnt);
434                         ce->ce_flags &= ~CE_UPDATE;
435                         if (o->update && !o->dry_run) {
436                                 errs |= checkout_entry(ce, &state, NULL, NULL);
437                         }
438                 }
439         }
440         stop_progress(&progress);
441         errs |= finish_delayed_checkout(&state, NULL);
442         if (o->update)
443                 git_attr_set_direction(GIT_ATTR_CHECKIN);
444
445         if (o->clone)
446                 report_collided_checkout(index);
447
448         trace_performance_leave("check_updates");
449         return errs != 0;
450 }
451
452 static int verify_uptodate_sparse(const struct cache_entry *ce,
453                                   struct unpack_trees_options *o);
454 static int verify_absent_sparse(const struct cache_entry *ce,
455                                 enum unpack_trees_error_types,
456                                 struct unpack_trees_options *o);
457
458 static int apply_sparse_checkout(struct index_state *istate,
459                                  struct cache_entry *ce,
460                                  struct unpack_trees_options *o)
461 {
462         int was_skip_worktree = ce_skip_worktree(ce);
463
464         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
465                 ce->ce_flags |= CE_SKIP_WORKTREE;
466         else
467                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
468         if (was_skip_worktree != ce_skip_worktree(ce)) {
469                 ce->ce_flags |= CE_UPDATE_IN_BASE;
470                 mark_fsmonitor_invalid(istate, ce);
471                 istate->cache_changed |= CE_ENTRY_CHANGED;
472         }
473
474         /*
475          * if (!was_skip_worktree && !ce_skip_worktree()) {
476          *      This is perfectly normal. Move on;
477          * }
478          */
479
480         /*
481          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
482          * area as a result of ce_skip_worktree() shortcuts in
483          * verify_absent() and verify_uptodate().
484          * Make sure they don't modify worktree if they are already
485          * outside checkout area
486          */
487         if (was_skip_worktree && ce_skip_worktree(ce)) {
488                 ce->ce_flags &= ~CE_UPDATE;
489
490                 /*
491                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
492                  * on to get that file removed from both index and worktree.
493                  * If that file is already outside worktree area, don't
494                  * bother remove it.
495                  */
496                 if (ce->ce_flags & CE_REMOVE)
497                         ce->ce_flags &= ~CE_WT_REMOVE;
498         }
499
500         if (!was_skip_worktree && ce_skip_worktree(ce)) {
501                 /*
502                  * If CE_UPDATE is set, verify_uptodate() must be called already
503                  * also stat info may have lost after merged_entry() so calling
504                  * verify_uptodate() again may fail
505                  */
506                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
507                         return -1;
508                 ce->ce_flags |= CE_WT_REMOVE;
509                 ce->ce_flags &= ~CE_UPDATE;
510         }
511         if (was_skip_worktree && !ce_skip_worktree(ce)) {
512                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
513                         return -1;
514                 ce->ce_flags |= CE_UPDATE;
515         }
516         return 0;
517 }
518
519 static inline int call_unpack_fn(const struct cache_entry * const *src,
520                                  struct unpack_trees_options *o)
521 {
522         int ret = o->fn(src, o);
523         if (ret > 0)
524                 ret = 0;
525         return ret;
526 }
527
528 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
529 {
530         ce->ce_flags |= CE_UNPACKED;
531
532         if (o->cache_bottom < o->src_index->cache_nr &&
533             o->src_index->cache[o->cache_bottom] == ce) {
534                 int bottom = o->cache_bottom;
535                 while (bottom < o->src_index->cache_nr &&
536                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
537                         bottom++;
538                 o->cache_bottom = bottom;
539         }
540 }
541
542 static void mark_all_ce_unused(struct index_state *index)
543 {
544         int i;
545         for (i = 0; i < index->cache_nr; i++)
546                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
547 }
548
549 static int locate_in_src_index(const struct cache_entry *ce,
550                                struct unpack_trees_options *o)
551 {
552         struct index_state *index = o->src_index;
553         int len = ce_namelen(ce);
554         int pos = index_name_pos(index, ce->name, len);
555         if (pos < 0)
556                 pos = -1 - pos;
557         return pos;
558 }
559
560 /*
561  * We call unpack_index_entry() with an unmerged cache entry
562  * only in diff-index, and it wants a single callback.  Skip
563  * the other unmerged entry with the same name.
564  */
565 static void mark_ce_used_same_name(struct cache_entry *ce,
566                                    struct unpack_trees_options *o)
567 {
568         struct index_state *index = o->src_index;
569         int len = ce_namelen(ce);
570         int pos;
571
572         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
573                 struct cache_entry *next = index->cache[pos];
574                 if (len != ce_namelen(next) ||
575                     memcmp(ce->name, next->name, len))
576                         break;
577                 mark_ce_used(next, o);
578         }
579 }
580
581 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
582 {
583         const struct index_state *index = o->src_index;
584         int pos = o->cache_bottom;
585
586         while (pos < index->cache_nr) {
587                 struct cache_entry *ce = index->cache[pos];
588                 if (!(ce->ce_flags & CE_UNPACKED))
589                         return ce;
590                 pos++;
591         }
592         return NULL;
593 }
594
595 static void add_same_unmerged(const struct cache_entry *ce,
596                               struct unpack_trees_options *o)
597 {
598         struct index_state *index = o->src_index;
599         int len = ce_namelen(ce);
600         int pos = index_name_pos(index, ce->name, len);
601
602         if (0 <= pos)
603                 die("programming error in a caller of mark_ce_used_same_name");
604         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
605                 struct cache_entry *next = index->cache[pos];
606                 if (len != ce_namelen(next) ||
607                     memcmp(ce->name, next->name, len))
608                         break;
609                 add_entry(o, next, 0, 0);
610                 mark_ce_used(next, o);
611         }
612 }
613
614 static int unpack_index_entry(struct cache_entry *ce,
615                               struct unpack_trees_options *o)
616 {
617         const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
618         int ret;
619
620         src[0] = ce;
621
622         mark_ce_used(ce, o);
623         if (ce_stage(ce)) {
624                 if (o->skip_unmerged) {
625                         add_entry(o, ce, 0, 0);
626                         return 0;
627                 }
628         }
629         ret = call_unpack_fn(src, o);
630         if (ce_stage(ce))
631                 mark_ce_used_same_name(ce, o);
632         return ret;
633 }
634
635 static int find_cache_pos(struct traverse_info *, const char *p, size_t len);
636
637 static void restore_cache_bottom(struct traverse_info *info, int bottom)
638 {
639         struct unpack_trees_options *o = info->data;
640
641         if (o->diff_index_cached)
642                 return;
643         o->cache_bottom = bottom;
644 }
645
646 static int switch_cache_bottom(struct traverse_info *info)
647 {
648         struct unpack_trees_options *o = info->data;
649         int ret, pos;
650
651         if (o->diff_index_cached)
652                 return 0;
653         ret = o->cache_bottom;
654         pos = find_cache_pos(info->prev, info->name, info->namelen);
655
656         if (pos < -1)
657                 o->cache_bottom = -2 - pos;
658         else if (pos < 0)
659                 o->cache_bottom = o->src_index->cache_nr;
660         return ret;
661 }
662
663 static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
664 {
665         return !is_null_oid(&name_j->oid) && !is_null_oid(&name_k->oid) && oideq(&name_j->oid, &name_k->oid);
666 }
667
668 static int all_trees_same_as_cache_tree(int n, unsigned long dirmask,
669                                         struct name_entry *names,
670                                         struct traverse_info *info)
671 {
672         struct unpack_trees_options *o = info->data;
673         int i;
674
675         if (!o->merge || dirmask != ((1 << n) - 1))
676                 return 0;
677
678         for (i = 1; i < n; i++)
679                 if (!are_same_oid(names, names + i))
680                         return 0;
681
682         return cache_tree_matches_traversal(o->src_index->cache_tree, names, info);
683 }
684
685 static int index_pos_by_traverse_info(struct name_entry *names,
686                                       struct traverse_info *info)
687 {
688         struct unpack_trees_options *o = info->data;
689         struct strbuf name = STRBUF_INIT;
690         int pos;
691
692         strbuf_make_traverse_path(&name, info, names->path, names->pathlen);
693         strbuf_addch(&name, '/');
694         pos = index_name_pos(o->src_index, name.buf, name.len);
695         if (pos >= 0)
696                 BUG("This is a directory and should not exist in index");
697         pos = -pos - 1;
698         if (!starts_with(o->src_index->cache[pos]->name, name.buf) ||
699             (pos > 0 && starts_with(o->src_index->cache[pos-1]->name, name.buf)))
700                 BUG("pos must point at the first entry in this directory");
701         strbuf_release(&name);
702         return pos;
703 }
704
705 /*
706  * Fast path if we detect that all trees are the same as cache-tree at this
707  * path. We'll walk these trees in an iterative loop using cache-tree/index
708  * instead of ODB since we already know what these trees contain.
709  */
710 static int traverse_by_cache_tree(int pos, int nr_entries, int nr_names,
711                                   struct traverse_info *info)
712 {
713         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
714         struct unpack_trees_options *o = info->data;
715         struct cache_entry *tree_ce = NULL;
716         int ce_len = 0;
717         int i, d;
718
719         if (!o->merge)
720                 BUG("We need cache-tree to do this optimization");
721
722         /*
723          * Do what unpack_callback() and unpack_nondirectories() normally
724          * do. But we walk all paths in an iterative loop instead.
725          *
726          * D/F conflicts and higher stage entries are not a concern
727          * because cache-tree would be invalidated and we would never
728          * get here in the first place.
729          */
730         for (i = 0; i < nr_entries; i++) {
731                 int new_ce_len, len, rc;
732
733                 src[0] = o->src_index->cache[pos + i];
734
735                 len = ce_namelen(src[0]);
736                 new_ce_len = cache_entry_size(len);
737
738                 if (new_ce_len > ce_len) {
739                         new_ce_len <<= 1;
740                         tree_ce = xrealloc(tree_ce, new_ce_len);
741                         memset(tree_ce, 0, new_ce_len);
742                         ce_len = new_ce_len;
743
744                         tree_ce->ce_flags = create_ce_flags(0);
745
746                         for (d = 1; d <= nr_names; d++)
747                                 src[d] = tree_ce;
748                 }
749
750                 tree_ce->ce_mode = src[0]->ce_mode;
751                 tree_ce->ce_namelen = len;
752                 oidcpy(&tree_ce->oid, &src[0]->oid);
753                 memcpy(tree_ce->name, src[0]->name, len + 1);
754
755                 rc = call_unpack_fn((const struct cache_entry * const *)src, o);
756                 if (rc < 0) {
757                         free(tree_ce);
758                         return rc;
759                 }
760
761                 mark_ce_used(src[0], o);
762         }
763         free(tree_ce);
764         if (o->debug_unpack)
765                 printf("Unpacked %d entries from %s to %s using cache-tree\n",
766                        nr_entries,
767                        o->src_index->cache[pos]->name,
768                        o->src_index->cache[pos + nr_entries - 1]->name);
769         return 0;
770 }
771
772 static int traverse_trees_recursive(int n, unsigned long dirmask,
773                                     unsigned long df_conflicts,
774                                     struct name_entry *names,
775                                     struct traverse_info *info)
776 {
777         struct unpack_trees_options *o = info->data;
778         int i, ret, bottom;
779         int nr_buf = 0;
780         struct tree_desc t[MAX_UNPACK_TREES];
781         void *buf[MAX_UNPACK_TREES];
782         struct traverse_info newinfo;
783         struct name_entry *p;
784         int nr_entries;
785
786         nr_entries = all_trees_same_as_cache_tree(n, dirmask, names, info);
787         if (nr_entries > 0) {
788                 int pos = index_pos_by_traverse_info(names, info);
789
790                 if (!o->merge || df_conflicts)
791                         BUG("Wrong condition to get here buddy");
792
793                 /*
794                  * All entries up to 'pos' must have been processed
795                  * (i.e. marked CE_UNPACKED) at this point. But to be safe,
796                  * save and restore cache_bottom anyway to not miss
797                  * unprocessed entries before 'pos'.
798                  */
799                 bottom = o->cache_bottom;
800                 ret = traverse_by_cache_tree(pos, nr_entries, n, info);
801                 o->cache_bottom = bottom;
802                 return ret;
803         }
804
805         p = names;
806         while (!p->mode)
807                 p++;
808
809         newinfo = *info;
810         newinfo.prev = info;
811         newinfo.pathspec = info->pathspec;
812         newinfo.name = p->path;
813         newinfo.namelen = p->pathlen;
814         newinfo.mode = p->mode;
815         newinfo.pathlen = st_add3(newinfo.pathlen, tree_entry_len(p), 1);
816         newinfo.df_conflicts |= df_conflicts;
817
818         /*
819          * Fetch the tree from the ODB for each peer directory in the
820          * n commits.
821          *
822          * For 2- and 3-way traversals, we try to avoid hitting the
823          * ODB twice for the same OID.  This should yield a nice speed
824          * up in checkouts and merges when the commits are similar.
825          *
826          * We don't bother doing the full O(n^2) search for larger n,
827          * because wider traversals don't happen that often and we
828          * avoid the search setup.
829          *
830          * When 2 peer OIDs are the same, we just copy the tree
831          * descriptor data.  This implicitly borrows the buffer
832          * data from the earlier cell.
833          */
834         for (i = 0; i < n; i++, dirmask >>= 1) {
835                 if (i > 0 && are_same_oid(&names[i], &names[i - 1]))
836                         t[i] = t[i - 1];
837                 else if (i > 1 && are_same_oid(&names[i], &names[i - 2]))
838                         t[i] = t[i - 2];
839                 else {
840                         const struct object_id *oid = NULL;
841                         if (dirmask & 1)
842                                 oid = &names[i].oid;
843                         buf[nr_buf++] = fill_tree_descriptor(the_repository, t + i, oid);
844                 }
845         }
846
847         bottom = switch_cache_bottom(&newinfo);
848         ret = traverse_trees(o->src_index, n, t, &newinfo);
849         restore_cache_bottom(&newinfo, bottom);
850
851         for (i = 0; i < nr_buf; i++)
852                 free(buf[i]);
853
854         return ret;
855 }
856
857 /*
858  * Compare the traverse-path to the cache entry without actually
859  * having to generate the textual representation of the traverse
860  * path.
861  *
862  * NOTE! This *only* compares up to the size of the traverse path
863  * itself - the caller needs to do the final check for the cache
864  * entry having more data at the end!
865  */
866 static int do_compare_entry_piecewise(const struct cache_entry *ce,
867                                       const struct traverse_info *info,
868                                       const char *name, size_t namelen,
869                                       unsigned mode)
870 {
871         int pathlen, ce_len;
872         const char *ce_name;
873
874         if (info->prev) {
875                 int cmp = do_compare_entry_piecewise(ce, info->prev,
876                                                      info->name, info->namelen,
877                                                      info->mode);
878                 if (cmp)
879                         return cmp;
880         }
881         pathlen = info->pathlen;
882         ce_len = ce_namelen(ce);
883
884         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
885         if (ce_len < pathlen)
886                 return -1;
887
888         ce_len -= pathlen;
889         ce_name = ce->name + pathlen;
890
891         return df_name_compare(ce_name, ce_len, S_IFREG, name, namelen, mode);
892 }
893
894 static int do_compare_entry(const struct cache_entry *ce,
895                             const struct traverse_info *info,
896                             const char *name, size_t namelen,
897                             unsigned mode)
898 {
899         int pathlen, ce_len;
900         const char *ce_name;
901         int cmp;
902
903         /*
904          * If we have not precomputed the traverse path, it is quicker
905          * to avoid doing so.  But if we have precomputed it,
906          * it is quicker to use the precomputed version.
907          */
908         if (!info->traverse_path)
909                 return do_compare_entry_piecewise(ce, info, name, namelen, mode);
910
911         cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
912         if (cmp)
913                 return cmp;
914
915         pathlen = info->pathlen;
916         ce_len = ce_namelen(ce);
917
918         if (ce_len < pathlen)
919                 return -1;
920
921         ce_len -= pathlen;
922         ce_name = ce->name + pathlen;
923
924         return df_name_compare(ce_name, ce_len, S_IFREG, name, namelen, mode);
925 }
926
927 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
928 {
929         int cmp = do_compare_entry(ce, info, n->path, n->pathlen, n->mode);
930         if (cmp)
931                 return cmp;
932
933         /*
934          * Even if the beginning compared identically, the ce should
935          * compare as bigger than a directory leading up to it!
936          */
937         return ce_namelen(ce) > traverse_path_len(info, tree_entry_len(n));
938 }
939
940 static int ce_in_traverse_path(const struct cache_entry *ce,
941                                const struct traverse_info *info)
942 {
943         if (!info->prev)
944                 return 1;
945         if (do_compare_entry(ce, info->prev,
946                              info->name, info->namelen, info->mode))
947                 return 0;
948         /*
949          * If ce (blob) is the same name as the path (which is a tree
950          * we will be descending into), it won't be inside it.
951          */
952         return (info->pathlen < ce_namelen(ce));
953 }
954
955 static struct cache_entry *create_ce_entry(const struct traverse_info *info,
956         const struct name_entry *n,
957         int stage,
958         struct index_state *istate,
959         int is_transient)
960 {
961         size_t len = traverse_path_len(info, tree_entry_len(n));
962         struct cache_entry *ce =
963                 is_transient ?
964                 make_empty_transient_cache_entry(len) :
965                 make_empty_cache_entry(istate, len);
966
967         ce->ce_mode = create_ce_mode(n->mode);
968         ce->ce_flags = create_ce_flags(stage);
969         ce->ce_namelen = len;
970         oidcpy(&ce->oid, &n->oid);
971         /* len+1 because the cache_entry allocates space for NUL */
972         make_traverse_path(ce->name, len + 1, info, n->path, n->pathlen);
973
974         return ce;
975 }
976
977 /*
978  * Note that traverse_by_cache_tree() duplicates some logic in this function
979  * without actually calling it. If you change the logic here you may need to
980  * check and change there as well.
981  */
982 static int unpack_nondirectories(int n, unsigned long mask,
983                                  unsigned long dirmask,
984                                  struct cache_entry **src,
985                                  const struct name_entry *names,
986                                  const struct traverse_info *info)
987 {
988         int i;
989         struct unpack_trees_options *o = info->data;
990         unsigned long conflicts = info->df_conflicts | dirmask;
991
992         /* Do we have *only* directories? Nothing to do */
993         if (mask == dirmask && !src[0])
994                 return 0;
995
996         /*
997          * Ok, we've filled in up to any potential index entry in src[0],
998          * now do the rest.
999          */
1000         for (i = 0; i < n; i++) {
1001                 int stage;
1002                 unsigned int bit = 1ul << i;
1003                 if (conflicts & bit) {
1004                         src[i + o->merge] = o->df_conflict_entry;
1005                         continue;
1006                 }
1007                 if (!(mask & bit))
1008                         continue;
1009                 if (!o->merge)
1010                         stage = 0;
1011                 else if (i + 1 < o->head_idx)
1012                         stage = 1;
1013                 else if (i + 1 > o->head_idx)
1014                         stage = 3;
1015                 else
1016                         stage = 2;
1017
1018                 /*
1019                  * If the merge bit is set, then the cache entries are
1020                  * discarded in the following block.  In this case,
1021                  * construct "transient" cache_entries, as they are
1022                  * not stored in the index.  otherwise construct the
1023                  * cache entry from the index aware logic.
1024                  */
1025                 src[i + o->merge] = create_ce_entry(info, names + i, stage, &o->result, o->merge);
1026         }
1027
1028         if (o->merge) {
1029                 int rc = call_unpack_fn((const struct cache_entry * const *)src,
1030                                         o);
1031                 for (i = 0; i < n; i++) {
1032                         struct cache_entry *ce = src[i + o->merge];
1033                         if (ce != o->df_conflict_entry)
1034                                 discard_cache_entry(ce);
1035                 }
1036                 return rc;
1037         }
1038
1039         for (i = 0; i < n; i++)
1040                 if (src[i] && src[i] != o->df_conflict_entry)
1041                         if (do_add_entry(o, src[i], 0, 0))
1042                                 return -1;
1043
1044         return 0;
1045 }
1046
1047 static int unpack_failed(struct unpack_trees_options *o, const char *message)
1048 {
1049         discard_index(&o->result);
1050         if (!o->quiet && !o->exiting_early) {
1051                 if (message)
1052                         return error("%s", message);
1053                 return -1;
1054         }
1055         return -1;
1056 }
1057
1058 /*
1059  * The tree traversal is looking at name p.  If we have a matching entry,
1060  * return it.  If name p is a directory in the index, do not return
1061  * anything, as we will want to match it when the traversal descends into
1062  * the directory.
1063  */
1064 static int find_cache_pos(struct traverse_info *info,
1065                           const char *p, size_t p_len)
1066 {
1067         int pos;
1068         struct unpack_trees_options *o = info->data;
1069         struct index_state *index = o->src_index;
1070         int pfxlen = info->pathlen;
1071
1072         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
1073                 const struct cache_entry *ce = index->cache[pos];
1074                 const char *ce_name, *ce_slash;
1075                 int cmp, ce_len;
1076
1077                 if (ce->ce_flags & CE_UNPACKED) {
1078                         /*
1079                          * cache_bottom entry is already unpacked, so
1080                          * we can never match it; don't check it
1081                          * again.
1082                          */
1083                         if (pos == o->cache_bottom)
1084                                 ++o->cache_bottom;
1085                         continue;
1086                 }
1087                 if (!ce_in_traverse_path(ce, info)) {
1088                         /*
1089                          * Check if we can skip future cache checks
1090                          * (because we're already past all possible
1091                          * entries in the traverse path).
1092                          */
1093                         if (info->traverse_path) {
1094                                 if (strncmp(ce->name, info->traverse_path,
1095                                             info->pathlen) > 0)
1096                                         break;
1097                         }
1098                         continue;
1099                 }
1100                 ce_name = ce->name + pfxlen;
1101                 ce_slash = strchr(ce_name, '/');
1102                 if (ce_slash)
1103                         ce_len = ce_slash - ce_name;
1104                 else
1105                         ce_len = ce_namelen(ce) - pfxlen;
1106                 cmp = name_compare(p, p_len, ce_name, ce_len);
1107                 /*
1108                  * Exact match; if we have a directory we need to
1109                  * delay returning it.
1110                  */
1111                 if (!cmp)
1112                         return ce_slash ? -2 - pos : pos;
1113                 if (0 < cmp)
1114                         continue; /* keep looking */
1115                 /*
1116                  * ce_name sorts after p->path; could it be that we
1117                  * have files under p->path directory in the index?
1118                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
1119                  * have "t/a" in the index.
1120                  */
1121                 if (p_len < ce_len && !memcmp(ce_name, p, p_len) &&
1122                     ce_name[p_len] < '/')
1123                         continue; /* keep looking */
1124                 break;
1125         }
1126         return -1;
1127 }
1128
1129 static struct cache_entry *find_cache_entry(struct traverse_info *info,
1130                                             const struct name_entry *p)
1131 {
1132         int pos = find_cache_pos(info, p->path, p->pathlen);
1133         struct unpack_trees_options *o = info->data;
1134
1135         if (0 <= pos)
1136                 return o->src_index->cache[pos];
1137         else
1138                 return NULL;
1139 }
1140
1141 static void debug_path(struct traverse_info *info)
1142 {
1143         if (info->prev) {
1144                 debug_path(info->prev);
1145                 if (*info->prev->name)
1146                         putchar('/');
1147         }
1148         printf("%s", info->name);
1149 }
1150
1151 static void debug_name_entry(int i, struct name_entry *n)
1152 {
1153         printf("ent#%d %06o %s\n", i,
1154                n->path ? n->mode : 0,
1155                n->path ? n->path : "(missing)");
1156 }
1157
1158 static void debug_unpack_callback(int n,
1159                                   unsigned long mask,
1160                                   unsigned long dirmask,
1161                                   struct name_entry *names,
1162                                   struct traverse_info *info)
1163 {
1164         int i;
1165         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
1166                mask, dirmask, n);
1167         debug_path(info);
1168         putchar('\n');
1169         for (i = 0; i < n; i++)
1170                 debug_name_entry(i, names + i);
1171 }
1172
1173 /*
1174  * Note that traverse_by_cache_tree() duplicates some logic in this function
1175  * without actually calling it. If you change the logic here you may need to
1176  * check and change there as well.
1177  */
1178 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
1179 {
1180         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
1181         struct unpack_trees_options *o = info->data;
1182         const struct name_entry *p = names;
1183
1184         /* Find first entry with a real name (we could use "mask" too) */
1185         while (!p->mode)
1186                 p++;
1187
1188         if (o->debug_unpack)
1189                 debug_unpack_callback(n, mask, dirmask, names, info);
1190
1191         /* Are we supposed to look at the index too? */
1192         if (o->merge) {
1193                 while (1) {
1194                         int cmp;
1195                         struct cache_entry *ce;
1196
1197                         if (o->diff_index_cached)
1198                                 ce = next_cache_entry(o);
1199                         else
1200                                 ce = find_cache_entry(info, p);
1201
1202                         if (!ce)
1203                                 break;
1204                         cmp = compare_entry(ce, info, p);
1205                         if (cmp < 0) {
1206                                 if (unpack_index_entry(ce, o) < 0)
1207                                         return unpack_failed(o, NULL);
1208                                 continue;
1209                         }
1210                         if (!cmp) {
1211                                 if (ce_stage(ce)) {
1212                                         /*
1213                                          * If we skip unmerged index
1214                                          * entries, we'll skip this
1215                                          * entry *and* the tree
1216                                          * entries associated with it!
1217                                          */
1218                                         if (o->skip_unmerged) {
1219                                                 add_same_unmerged(ce, o);
1220                                                 return mask;
1221                                         }
1222                                 }
1223                                 src[0] = ce;
1224                         }
1225                         break;
1226                 }
1227         }
1228
1229         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
1230                 return -1;
1231
1232         if (o->merge && src[0]) {
1233                 if (ce_stage(src[0]))
1234                         mark_ce_used_same_name(src[0], o);
1235                 else
1236                         mark_ce_used(src[0], o);
1237         }
1238
1239         /* Now handle any directories.. */
1240         if (dirmask) {
1241                 /* special case: "diff-index --cached" looking at a tree */
1242                 if (o->diff_index_cached &&
1243                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
1244                         int matches;
1245                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
1246                                                                names, info);
1247                         /*
1248                          * Everything under the name matches; skip the
1249                          * entire hierarchy.  diff_index_cached codepath
1250                          * special cases D/F conflicts in such a way that
1251                          * it does not do any look-ahead, so this is safe.
1252                          */
1253                         if (matches) {
1254                                 o->cache_bottom += matches;
1255                                 return mask;
1256                         }
1257                 }
1258
1259                 if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
1260                                              names, info) < 0)
1261                         return -1;
1262                 return mask;
1263         }
1264
1265         return mask;
1266 }
1267
1268 static int clear_ce_flags_1(struct index_state *istate,
1269                             struct cache_entry **cache, int nr,
1270                             struct strbuf *prefix,
1271                             int select_mask, int clear_mask,
1272                             struct pattern_list *pl,
1273                             enum pattern_match_result default_match);
1274
1275 /* Whole directory matching */
1276 static int clear_ce_flags_dir(struct index_state *istate,
1277                               struct cache_entry **cache, int nr,
1278                               struct strbuf *prefix,
1279                               char *basename,
1280                               int select_mask, int clear_mask,
1281                               struct pattern_list *pl,
1282                               enum pattern_match_result default_match)
1283 {
1284         struct cache_entry **cache_end;
1285         int dtype = DT_DIR;
1286         int rc;
1287         enum pattern_match_result ret;
1288         ret = path_matches_pattern_list(prefix->buf, prefix->len,
1289                                         basename, &dtype, pl, istate);
1290
1291         strbuf_addch(prefix, '/');
1292
1293         /* If undecided, use matching result of parent dir in defval */
1294         if (ret == UNDECIDED)
1295                 ret = default_match;
1296
1297         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
1298                 struct cache_entry *ce = *cache_end;
1299                 if (strncmp(ce->name, prefix->buf, prefix->len))
1300                         break;
1301         }
1302
1303         /*
1304          * TODO: check pl, if there are no patterns that may conflict
1305          * with ret (iow, we know in advance the incl/excl
1306          * decision for the entire directory), clear flag here without
1307          * calling clear_ce_flags_1(). That function will call
1308          * the expensive path_matches_pattern_list() on every entry.
1309          */
1310         rc = clear_ce_flags_1(istate, cache, cache_end - cache,
1311                               prefix,
1312                               select_mask, clear_mask,
1313                               pl, ret);
1314         strbuf_setlen(prefix, prefix->len - 1);
1315         return rc;
1316 }
1317
1318 /*
1319  * Traverse the index, find every entry that matches according to
1320  * o->pl. Do "ce_flags &= ~clear_mask" on those entries. Return the
1321  * number of traversed entries.
1322  *
1323  * If select_mask is non-zero, only entries whose ce_flags has on of
1324  * those bits enabled are traversed.
1325  *
1326  * cache        : pointer to an index entry
1327  * prefix_len   : an offset to its path
1328  *
1329  * The current path ("prefix") including the trailing '/' is
1330  *   cache[0]->name[0..(prefix_len-1)]
1331  * Top level path has prefix_len zero.
1332  */
1333 static int clear_ce_flags_1(struct index_state *istate,
1334                             struct cache_entry **cache, int nr,
1335                             struct strbuf *prefix,
1336                             int select_mask, int clear_mask,
1337                             struct pattern_list *pl,
1338                             enum pattern_match_result default_match)
1339 {
1340         struct cache_entry **cache_end = cache + nr;
1341
1342         /*
1343          * Process all entries that have the given prefix and meet
1344          * select_mask condition
1345          */
1346         while(cache != cache_end) {
1347                 struct cache_entry *ce = *cache;
1348                 const char *name, *slash;
1349                 int len, dtype;
1350                 enum pattern_match_result ret;
1351
1352                 if (select_mask && !(ce->ce_flags & select_mask)) {
1353                         cache++;
1354                         continue;
1355                 }
1356
1357                 if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
1358                         break;
1359
1360                 name = ce->name + prefix->len;
1361                 slash = strchr(name, '/');
1362
1363                 /* If it's a directory, try whole directory match first */
1364                 if (slash) {
1365                         int processed;
1366
1367                         len = slash - name;
1368                         strbuf_add(prefix, name, len);
1369
1370                         processed = clear_ce_flags_dir(istate, cache, cache_end - cache,
1371                                                        prefix,
1372                                                        prefix->buf + prefix->len - len,
1373                                                        select_mask, clear_mask,
1374                                                        pl, default_match);
1375
1376                         /* clear_c_f_dir eats a whole dir already? */
1377                         if (processed) {
1378                                 cache += processed;
1379                                 strbuf_setlen(prefix, prefix->len - len);
1380                                 continue;
1381                         }
1382
1383                         strbuf_addch(prefix, '/');
1384                         cache += clear_ce_flags_1(istate, cache, cache_end - cache,
1385                                                   prefix,
1386                                                   select_mask, clear_mask, pl,
1387                                                   default_match);
1388                         strbuf_setlen(prefix, prefix->len - len - 1);
1389                         continue;
1390                 }
1391
1392                 /* Non-directory */
1393                 dtype = ce_to_dtype(ce);
1394                 ret = path_matches_pattern_list(ce->name,
1395                                                 ce_namelen(ce),
1396                                                 name, &dtype, pl, istate);
1397                 if (ret == UNDECIDED)
1398                         ret = default_match;
1399                 if (ret == MATCHED)
1400                         ce->ce_flags &= ~clear_mask;
1401                 cache++;
1402         }
1403         return nr - (cache_end - cache);
1404 }
1405
1406 static int clear_ce_flags(struct index_state *istate,
1407                           int select_mask, int clear_mask,
1408                           struct pattern_list *pl)
1409 {
1410         static struct strbuf prefix = STRBUF_INIT;
1411
1412         strbuf_reset(&prefix);
1413
1414         return clear_ce_flags_1(istate,
1415                                 istate->cache,
1416                                 istate->cache_nr,
1417                                 &prefix,
1418                                 select_mask, clear_mask,
1419                                 pl, 0);
1420 }
1421
1422 /*
1423  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1424  */
1425 static void mark_new_skip_worktree(struct pattern_list *pl,
1426                                    struct index_state *istate,
1427                                    int select_flag, int skip_wt_flag)
1428 {
1429         int i;
1430
1431         /*
1432          * 1. Pretend the narrowest worktree: only unmerged entries
1433          * are checked out
1434          */
1435         for (i = 0; i < istate->cache_nr; i++) {
1436                 struct cache_entry *ce = istate->cache[i];
1437
1438                 if (select_flag && !(ce->ce_flags & select_flag))
1439                         continue;
1440
1441                 if (!ce_stage(ce) && !(ce->ce_flags & CE_CONFLICTED))
1442                         ce->ce_flags |= skip_wt_flag;
1443                 else
1444                         ce->ce_flags &= ~skip_wt_flag;
1445         }
1446
1447         /*
1448          * 2. Widen worktree according to sparse-checkout file.
1449          * Matched entries will have skip_wt_flag cleared (i.e. "in")
1450          */
1451         clear_ce_flags(istate, select_flag, skip_wt_flag, pl);
1452 }
1453
1454 static int verify_absent(const struct cache_entry *,
1455                          enum unpack_trees_error_types,
1456                          struct unpack_trees_options *);
1457 /*
1458  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1459  * resulting index, -2 on failure to reflect the changes to the work tree.
1460  *
1461  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1462  */
1463 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1464 {
1465         int i, ret;
1466         static struct cache_entry *dfc;
1467         struct pattern_list pl;
1468
1469         if (len > MAX_UNPACK_TREES)
1470                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1471
1472         trace_performance_enter();
1473         memset(&pl, 0, sizeof(pl));
1474         if (!core_apply_sparse_checkout || !o->update)
1475                 o->skip_sparse_checkout = 1;
1476         if (!o->skip_sparse_checkout) {
1477                 char *sparse = git_pathdup("info/sparse-checkout");
1478                 if (add_patterns_from_file_to_list(sparse, "", 0, &pl, NULL) < 0)
1479                         o->skip_sparse_checkout = 1;
1480                 else
1481                         o->pl = &pl;
1482                 free(sparse);
1483         }
1484
1485         memset(&o->result, 0, sizeof(o->result));
1486         o->result.initialized = 1;
1487         o->result.timestamp.sec = o->src_index->timestamp.sec;
1488         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1489         o->result.version = o->src_index->version;
1490         if (!o->src_index->split_index) {
1491                 o->result.split_index = NULL;
1492         } else if (o->src_index == o->dst_index) {
1493                 /*
1494                  * o->dst_index (and thus o->src_index) will be discarded
1495                  * and overwritten with o->result at the end of this function,
1496                  * so just use src_index's split_index to avoid having to
1497                  * create a new one.
1498                  */
1499                 o->result.split_index = o->src_index->split_index;
1500                 o->result.split_index->refcount++;
1501         } else {
1502                 o->result.split_index = init_split_index(&o->result);
1503         }
1504         oidcpy(&o->result.oid, &o->src_index->oid);
1505         o->merge_size = len;
1506         mark_all_ce_unused(o->src_index);
1507
1508         /*
1509          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1510          */
1511         if (!o->skip_sparse_checkout)
1512                 mark_new_skip_worktree(o->pl, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1513
1514         if (!dfc)
1515                 dfc = xcalloc(1, cache_entry_size(0));
1516         o->df_conflict_entry = dfc;
1517
1518         if (len) {
1519                 const char *prefix = o->prefix ? o->prefix : "";
1520                 struct traverse_info info;
1521
1522                 setup_traverse_info(&info, prefix);
1523                 info.fn = unpack_callback;
1524                 info.data = o;
1525                 info.show_all_errors = o->show_all_errors;
1526                 info.pathspec = o->pathspec;
1527
1528                 if (o->prefix) {
1529                         /*
1530                          * Unpack existing index entries that sort before the
1531                          * prefix the tree is spliced into.  Note that o->merge
1532                          * is always true in this case.
1533                          */
1534                         while (1) {
1535                                 struct cache_entry *ce = next_cache_entry(o);
1536                                 if (!ce)
1537                                         break;
1538                                 if (ce_in_traverse_path(ce, &info))
1539                                         break;
1540                                 if (unpack_index_entry(ce, o) < 0)
1541                                         goto return_failed;
1542                         }
1543                 }
1544
1545                 trace_performance_enter();
1546                 ret = traverse_trees(o->src_index, len, t, &info);
1547                 trace_performance_leave("traverse_trees");
1548                 if (ret < 0)
1549                         goto return_failed;
1550         }
1551
1552         /* Any left-over entries in the index? */
1553         if (o->merge) {
1554                 while (1) {
1555                         struct cache_entry *ce = next_cache_entry(o);
1556                         if (!ce)
1557                                 break;
1558                         if (unpack_index_entry(ce, o) < 0)
1559                                 goto return_failed;
1560                 }
1561         }
1562         mark_all_ce_unused(o->src_index);
1563
1564         if (o->trivial_merges_only && o->nontrivial_merge) {
1565                 ret = unpack_failed(o, "Merge requires file-level merging");
1566                 goto done;
1567         }
1568
1569         if (!o->skip_sparse_checkout) {
1570                 int empty_worktree = 1;
1571
1572                 /*
1573                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1574                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1575                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1576                  */
1577                 mark_new_skip_worktree(o->pl, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1578
1579                 ret = 0;
1580                 for (i = 0; i < o->result.cache_nr; i++) {
1581                         struct cache_entry *ce = o->result.cache[i];
1582
1583                         /*
1584                          * Entries marked with CE_ADDED in merged_entry() do not have
1585                          * verify_absent() check (the check is effectively disabled
1586                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1587                          *
1588                          * Do the real check now because we have had
1589                          * correct CE_NEW_SKIP_WORKTREE
1590                          */
1591                         if (ce->ce_flags & CE_ADDED &&
1592                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1593                                 if (!o->show_all_errors)
1594                                         goto return_failed;
1595                                 ret = -1;
1596                         }
1597
1598                         if (apply_sparse_checkout(&o->result, ce, o)) {
1599                                 if (!o->show_all_errors)
1600                                         goto return_failed;
1601                                 ret = -1;
1602                         }
1603                         if (!ce_skip_worktree(ce))
1604                                 empty_worktree = 0;
1605
1606                 }
1607                 if (ret < 0)
1608                         goto return_failed;
1609                 /*
1610                  * Sparse checkout is meant to narrow down checkout area
1611                  * but it does not make sense to narrow down to empty working
1612                  * tree. This is usually a mistake in sparse checkout rules.
1613                  * Do not allow users to do that.
1614                  */
1615                 if (o->result.cache_nr && empty_worktree) {
1616                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1617                         goto done;
1618                 }
1619         }
1620
1621         ret = check_updates(o) ? (-2) : 0;
1622         if (o->dst_index) {
1623                 move_index_extensions(&o->result, o->src_index);
1624                 if (!ret) {
1625                         if (git_env_bool("GIT_TEST_CHECK_CACHE_TREE", 0))
1626                                 cache_tree_verify(the_repository, &o->result);
1627                         if (!o->result.cache_tree)
1628                                 o->result.cache_tree = cache_tree();
1629                         if (!cache_tree_fully_valid(o->result.cache_tree))
1630                                 cache_tree_update(&o->result,
1631                                                   WRITE_TREE_SILENT |
1632                                                   WRITE_TREE_REPAIR);
1633                 }
1634
1635                 o->result.updated_workdir = 1;
1636                 discard_index(o->dst_index);
1637                 *o->dst_index = o->result;
1638         } else {
1639                 discard_index(&o->result);
1640         }
1641         o->src_index = NULL;
1642
1643 done:
1644         trace_performance_leave("unpack_trees");
1645         clear_pattern_list(&pl);
1646         return ret;
1647
1648 return_failed:
1649         if (o->show_all_errors)
1650                 display_error_msgs(o);
1651         mark_all_ce_unused(o->src_index);
1652         ret = unpack_failed(o, NULL);
1653         if (o->exiting_early)
1654                 ret = 0;
1655         goto done;
1656 }
1657
1658 /* Here come the merge functions */
1659
1660 static int reject_merge(const struct cache_entry *ce,
1661                         struct unpack_trees_options *o)
1662 {
1663         return add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1664 }
1665
1666 static int same(const struct cache_entry *a, const struct cache_entry *b)
1667 {
1668         if (!!a != !!b)
1669                 return 0;
1670         if (!a && !b)
1671                 return 1;
1672         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1673                 return 0;
1674         return a->ce_mode == b->ce_mode &&
1675                oideq(&a->oid, &b->oid);
1676 }
1677
1678
1679 /*
1680  * When a CE gets turned into an unmerged entry, we
1681  * want it to be up-to-date
1682  */
1683 static int verify_uptodate_1(const struct cache_entry *ce,
1684                              struct unpack_trees_options *o,
1685                              enum unpack_trees_error_types error_type)
1686 {
1687         struct stat st;
1688
1689         if (o->index_only)
1690                 return 0;
1691
1692         /*
1693          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1694          * if this entry is truly up-to-date because this file may be
1695          * overwritten.
1696          */
1697         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1698                 ; /* keep checking */
1699         else if (o->reset || ce_uptodate(ce))
1700                 return 0;
1701
1702         if (!lstat(ce->name, &st)) {
1703                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1704                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1705
1706                 if (submodule_from_ce(ce)) {
1707                         int r = check_submodule_move_head(ce,
1708                                 "HEAD", oid_to_hex(&ce->oid), o);
1709                         if (r)
1710                                 return add_rejected_path(o, error_type, ce->name);
1711                         return 0;
1712                 }
1713
1714                 if (!changed)
1715                         return 0;
1716                 /*
1717                  * Historic default policy was to allow submodule to be out
1718                  * of sync wrt the superproject index. If the submodule was
1719                  * not considered interesting above, we don't care here.
1720                  */
1721                 if (S_ISGITLINK(ce->ce_mode))
1722                         return 0;
1723
1724                 errno = 0;
1725         }
1726         if (errno == ENOENT)
1727                 return 0;
1728         return add_rejected_path(o, error_type, ce->name);
1729 }
1730
1731 int verify_uptodate(const struct cache_entry *ce,
1732                     struct unpack_trees_options *o)
1733 {
1734         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1735                 return 0;
1736         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1737 }
1738
1739 static int verify_uptodate_sparse(const struct cache_entry *ce,
1740                                   struct unpack_trees_options *o)
1741 {
1742         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1743 }
1744
1745 /*
1746  * TODO: We should actually invalidate o->result, not src_index [1].
1747  * But since cache tree and untracked cache both are not copied to
1748  * o->result until unpacking is complete, we invalidate them on
1749  * src_index instead with the assumption that they will be copied to
1750  * dst_index at the end.
1751  *
1752  * [1] src_index->cache_tree is also used in unpack_callback() so if
1753  * we invalidate o->result, we need to update it to use
1754  * o->result.cache_tree as well.
1755  */
1756 static void invalidate_ce_path(const struct cache_entry *ce,
1757                                struct unpack_trees_options *o)
1758 {
1759         if (!ce)
1760                 return;
1761         cache_tree_invalidate_path(o->src_index, ce->name);
1762         untracked_cache_invalidate_path(o->src_index, ce->name, 1);
1763 }
1764
1765 /*
1766  * Check that checking out ce->sha1 in subdir ce->name is not
1767  * going to overwrite any working files.
1768  *
1769  * Currently, git does not checkout subprojects during a superproject
1770  * checkout, so it is not going to overwrite anything.
1771  */
1772 static int verify_clean_submodule(const char *old_sha1,
1773                                   const struct cache_entry *ce,
1774                                   struct unpack_trees_options *o)
1775 {
1776         if (!submodule_from_ce(ce))
1777                 return 0;
1778
1779         return check_submodule_move_head(ce, old_sha1,
1780                                          oid_to_hex(&ce->oid), o);
1781 }
1782
1783 static int verify_clean_subdirectory(const struct cache_entry *ce,
1784                                      struct unpack_trees_options *o)
1785 {
1786         /*
1787          * we are about to extract "ce->name"; we would not want to lose
1788          * anything in the existing directory there.
1789          */
1790         int namelen;
1791         int i;
1792         struct dir_struct d;
1793         char *pathbuf;
1794         int cnt = 0;
1795
1796         if (S_ISGITLINK(ce->ce_mode)) {
1797                 struct object_id oid;
1798                 int sub_head = resolve_gitlink_ref(ce->name, "HEAD", &oid);
1799                 /*
1800                  * If we are not going to update the submodule, then
1801                  * we don't care.
1802                  */
1803                 if (!sub_head && oideq(&oid, &ce->oid))
1804                         return 0;
1805                 return verify_clean_submodule(sub_head ? NULL : oid_to_hex(&oid),
1806                                               ce, o);
1807         }
1808
1809         /*
1810          * First let's make sure we do not have a local modification
1811          * in that directory.
1812          */
1813         namelen = ce_namelen(ce);
1814         for (i = locate_in_src_index(ce, o);
1815              i < o->src_index->cache_nr;
1816              i++) {
1817                 struct cache_entry *ce2 = o->src_index->cache[i];
1818                 int len = ce_namelen(ce2);
1819                 if (len < namelen ||
1820                     strncmp(ce->name, ce2->name, namelen) ||
1821                     ce2->name[namelen] != '/')
1822                         break;
1823                 /*
1824                  * ce2->name is an entry in the subdirectory to be
1825                  * removed.
1826                  */
1827                 if (!ce_stage(ce2)) {
1828                         if (verify_uptodate(ce2, o))
1829                                 return -1;
1830                         add_entry(o, ce2, CE_REMOVE, 0);
1831                         invalidate_ce_path(ce, o);
1832                         mark_ce_used(ce2, o);
1833                 }
1834                 cnt++;
1835         }
1836
1837         /*
1838          * Then we need to make sure that we do not lose a locally
1839          * present file that is not ignored.
1840          */
1841         pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1842
1843         memset(&d, 0, sizeof(d));
1844         if (o->dir)
1845                 d.exclude_per_dir = o->dir->exclude_per_dir;
1846         i = read_directory(&d, o->src_index, pathbuf, namelen+1, NULL);
1847         if (i)
1848                 return add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1849         free(pathbuf);
1850         return cnt;
1851 }
1852
1853 /*
1854  * This gets called when there was no index entry for the tree entry 'dst',
1855  * but we found a file in the working tree that 'lstat()' said was fine,
1856  * and we're on a case-insensitive filesystem.
1857  *
1858  * See if we can find a case-insensitive match in the index that also
1859  * matches the stat information, and assume it's that other file!
1860  */
1861 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1862 {
1863         const struct cache_entry *src;
1864
1865         src = index_file_exists(o->src_index, name, len, 1);
1866         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1867 }
1868
1869 static int check_ok_to_remove(const char *name, int len, int dtype,
1870                               const struct cache_entry *ce, struct stat *st,
1871                               enum unpack_trees_error_types error_type,
1872                               struct unpack_trees_options *o)
1873 {
1874         const struct cache_entry *result;
1875
1876         /*
1877          * It may be that the 'lstat()' succeeded even though
1878          * target 'ce' was absent, because there is an old
1879          * entry that is different only in case..
1880          *
1881          * Ignore that lstat() if it matches.
1882          */
1883         if (ignore_case && icase_exists(o, name, len, st))
1884                 return 0;
1885
1886         if (o->dir &&
1887             is_excluded(o->dir, o->src_index, name, &dtype))
1888                 /*
1889                  * ce->name is explicitly excluded, so it is Ok to
1890                  * overwrite it.
1891                  */
1892                 return 0;
1893         if (S_ISDIR(st->st_mode)) {
1894                 /*
1895                  * We are checking out path "foo" and
1896                  * found "foo/." in the working tree.
1897                  * This is tricky -- if we have modified
1898                  * files that are in "foo/" we would lose
1899                  * them.
1900                  */
1901                 if (verify_clean_subdirectory(ce, o) < 0)
1902                         return -1;
1903                 return 0;
1904         }
1905
1906         /*
1907          * The previous round may already have decided to
1908          * delete this path, which is in a subdirectory that
1909          * is being replaced with a blob.
1910          */
1911         result = index_file_exists(&o->result, name, len, 0);
1912         if (result) {
1913                 if (result->ce_flags & CE_REMOVE)
1914                         return 0;
1915         }
1916
1917         return add_rejected_path(o, error_type, name);
1918 }
1919
1920 /*
1921  * We do not want to remove or overwrite a working tree file that
1922  * is not tracked, unless it is ignored.
1923  */
1924 static int verify_absent_1(const struct cache_entry *ce,
1925                            enum unpack_trees_error_types error_type,
1926                            struct unpack_trees_options *o)
1927 {
1928         int len;
1929         struct stat st;
1930
1931         if (o->index_only || o->reset || !o->update)
1932                 return 0;
1933
1934         len = check_leading_path(ce->name, ce_namelen(ce));
1935         if (!len)
1936                 return 0;
1937         else if (len > 0) {
1938                 char *path;
1939                 int ret;
1940
1941                 path = xmemdupz(ce->name, len);
1942                 if (lstat(path, &st))
1943                         ret = error_errno("cannot stat '%s'", path);
1944                 else {
1945                         if (submodule_from_ce(ce))
1946                                 ret = check_submodule_move_head(ce,
1947                                                                 oid_to_hex(&ce->oid),
1948                                                                 NULL, o);
1949                         else
1950                                 ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
1951                                                          &st, error_type, o);
1952                 }
1953                 free(path);
1954                 return ret;
1955         } else if (lstat(ce->name, &st)) {
1956                 if (errno != ENOENT)
1957                         return error_errno("cannot stat '%s'", ce->name);
1958                 return 0;
1959         } else {
1960                 if (submodule_from_ce(ce))
1961                         return check_submodule_move_head(ce, oid_to_hex(&ce->oid),
1962                                                          NULL, o);
1963
1964                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1965                                           ce_to_dtype(ce), ce, &st,
1966                                           error_type, o);
1967         }
1968 }
1969
1970 static int verify_absent(const struct cache_entry *ce,
1971                          enum unpack_trees_error_types error_type,
1972                          struct unpack_trees_options *o)
1973 {
1974         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1975                 return 0;
1976         return verify_absent_1(ce, error_type, o);
1977 }
1978
1979 static int verify_absent_sparse(const struct cache_entry *ce,
1980                                 enum unpack_trees_error_types error_type,
1981                                 struct unpack_trees_options *o)
1982 {
1983         enum unpack_trees_error_types orphaned_error = error_type;
1984         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1985                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1986
1987         return verify_absent_1(ce, orphaned_error, o);
1988 }
1989
1990 static int merged_entry(const struct cache_entry *ce,
1991                         const struct cache_entry *old,
1992                         struct unpack_trees_options *o)
1993 {
1994         int update = CE_UPDATE;
1995         struct cache_entry *merge = dup_cache_entry(ce, &o->result);
1996
1997         if (!old) {
1998                 /*
1999                  * New index entries. In sparse checkout, the following
2000                  * verify_absent() will be delayed until after
2001                  * traverse_trees() finishes in unpack_trees(), then:
2002                  *
2003                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
2004                  *  - verify_absent() be called again, this time with
2005                  *    correct CE_NEW_SKIP_WORKTREE
2006                  *
2007                  * verify_absent() call here does nothing in sparse
2008                  * checkout (i.e. o->skip_sparse_checkout == 0)
2009                  */
2010                 update |= CE_ADDED;
2011                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
2012
2013                 if (verify_absent(merge,
2014                                   ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
2015                         discard_cache_entry(merge);
2016                         return -1;
2017                 }
2018                 invalidate_ce_path(merge, o);
2019
2020                 if (submodule_from_ce(ce)) {
2021                         int ret = check_submodule_move_head(ce, NULL,
2022                                                             oid_to_hex(&ce->oid),
2023                                                             o);
2024                         if (ret)
2025                                 return ret;
2026                 }
2027
2028         } else if (!(old->ce_flags & CE_CONFLICTED)) {
2029                 /*
2030                  * See if we can re-use the old CE directly?
2031                  * That way we get the uptodate stat info.
2032                  *
2033                  * This also removes the UPDATE flag on a match; otherwise
2034                  * we will end up overwriting local changes in the work tree.
2035                  */
2036                 if (same(old, merge)) {
2037                         copy_cache_entry(merge, old);
2038                         update = 0;
2039                 } else {
2040                         if (verify_uptodate(old, o)) {
2041                                 discard_cache_entry(merge);
2042                                 return -1;
2043                         }
2044                         /* Migrate old flags over */
2045                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
2046                         invalidate_ce_path(old, o);
2047                 }
2048
2049                 if (submodule_from_ce(ce)) {
2050                         int ret = check_submodule_move_head(ce, oid_to_hex(&old->oid),
2051                                                             oid_to_hex(&ce->oid),
2052                                                             o);
2053                         if (ret)
2054                                 return ret;
2055                 }
2056         } else {
2057                 /*
2058                  * Previously unmerged entry left as an existence
2059                  * marker by read_index_unmerged();
2060                  */
2061                 invalidate_ce_path(old, o);
2062         }
2063
2064         do_add_entry(o, merge, update, CE_STAGEMASK);
2065         return 1;
2066 }
2067
2068 static int deleted_entry(const struct cache_entry *ce,
2069                          const struct cache_entry *old,
2070                          struct unpack_trees_options *o)
2071 {
2072         /* Did it exist in the index? */
2073         if (!old) {
2074                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
2075                         return -1;
2076                 return 0;
2077         }
2078         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
2079                 return -1;
2080         add_entry(o, ce, CE_REMOVE, 0);
2081         invalidate_ce_path(ce, o);
2082         return 1;
2083 }
2084
2085 static int keep_entry(const struct cache_entry *ce,
2086                       struct unpack_trees_options *o)
2087 {
2088         add_entry(o, ce, 0, 0);
2089         if (ce_stage(ce))
2090                 invalidate_ce_path(ce, o);
2091         return 1;
2092 }
2093
2094 #if DBRT_DEBUG
2095 static void show_stage_entry(FILE *o,
2096                              const char *label, const struct cache_entry *ce)
2097 {
2098         if (!ce)
2099                 fprintf(o, "%s (missing)\n", label);
2100         else
2101                 fprintf(o, "%s%06o %s %d\t%s\n",
2102                         label,
2103                         ce->ce_mode,
2104                         oid_to_hex(&ce->oid),
2105                         ce_stage(ce),
2106                         ce->name);
2107 }
2108 #endif
2109
2110 int threeway_merge(const struct cache_entry * const *stages,
2111                    struct unpack_trees_options *o)
2112 {
2113         const struct cache_entry *index;
2114         const struct cache_entry *head;
2115         const struct cache_entry *remote = stages[o->head_idx + 1];
2116         int count;
2117         int head_match = 0;
2118         int remote_match = 0;
2119
2120         int df_conflict_head = 0;
2121         int df_conflict_remote = 0;
2122
2123         int any_anc_missing = 0;
2124         int no_anc_exists = 1;
2125         int i;
2126
2127         for (i = 1; i < o->head_idx; i++) {
2128                 if (!stages[i] || stages[i] == o->df_conflict_entry)
2129                         any_anc_missing = 1;
2130                 else
2131                         no_anc_exists = 0;
2132         }
2133
2134         index = stages[0];
2135         head = stages[o->head_idx];
2136
2137         if (head == o->df_conflict_entry) {
2138                 df_conflict_head = 1;
2139                 head = NULL;
2140         }
2141
2142         if (remote == o->df_conflict_entry) {
2143                 df_conflict_remote = 1;
2144                 remote = NULL;
2145         }
2146
2147         /*
2148          * First, if there's a #16 situation, note that to prevent #13
2149          * and #14.
2150          */
2151         if (!same(remote, head)) {
2152                 for (i = 1; i < o->head_idx; i++) {
2153                         if (same(stages[i], head)) {
2154                                 head_match = i;
2155                         }
2156                         if (same(stages[i], remote)) {
2157                                 remote_match = i;
2158                         }
2159                 }
2160         }
2161
2162         /*
2163          * We start with cases where the index is allowed to match
2164          * something other than the head: #14(ALT) and #2ALT, where it
2165          * is permitted to match the result instead.
2166          */
2167         /* #14, #14ALT, #2ALT */
2168         if (remote && !df_conflict_head && head_match && !remote_match) {
2169                 if (index && !same(index, remote) && !same(index, head))
2170                         return reject_merge(index, o);
2171                 return merged_entry(remote, index, o);
2172         }
2173         /*
2174          * If we have an entry in the index cache, then we want to
2175          * make sure that it matches head.
2176          */
2177         if (index && !same(index, head))
2178                 return reject_merge(index, o);
2179
2180         if (head) {
2181                 /* #5ALT, #15 */
2182                 if (same(head, remote))
2183                         return merged_entry(head, index, o);
2184                 /* #13, #3ALT */
2185                 if (!df_conflict_remote && remote_match && !head_match)
2186                         return merged_entry(head, index, o);
2187         }
2188
2189         /* #1 */
2190         if (!head && !remote && any_anc_missing)
2191                 return 0;
2192
2193         /*
2194          * Under the "aggressive" rule, we resolve mostly trivial
2195          * cases that we historically had git-merge-one-file resolve.
2196          */
2197         if (o->aggressive) {
2198                 int head_deleted = !head;
2199                 int remote_deleted = !remote;
2200                 const struct cache_entry *ce = NULL;
2201
2202                 if (index)
2203                         ce = index;
2204                 else if (head)
2205                         ce = head;
2206                 else if (remote)
2207                         ce = remote;
2208                 else {
2209                         for (i = 1; i < o->head_idx; i++) {
2210                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
2211                                         ce = stages[i];
2212                                         break;
2213                                 }
2214                         }
2215                 }
2216
2217                 /*
2218                  * Deleted in both.
2219                  * Deleted in one and unchanged in the other.
2220                  */
2221                 if ((head_deleted && remote_deleted) ||
2222                     (head_deleted && remote && remote_match) ||
2223                     (remote_deleted && head && head_match)) {
2224                         if (index)
2225                                 return deleted_entry(index, index, o);
2226                         if (ce && !head_deleted) {
2227                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
2228                                         return -1;
2229                         }
2230                         return 0;
2231                 }
2232                 /*
2233                  * Added in both, identically.
2234                  */
2235                 if (no_anc_exists && head && remote && same(head, remote))
2236                         return merged_entry(head, index, o);
2237
2238         }
2239
2240         /* Below are "no merge" cases, which require that the index be
2241          * up-to-date to avoid the files getting overwritten with
2242          * conflict resolution files.
2243          */
2244         if (index) {
2245                 if (verify_uptodate(index, o))
2246                         return -1;
2247         }
2248
2249         o->nontrivial_merge = 1;
2250
2251         /* #2, #3, #4, #6, #7, #9, #10, #11. */
2252         count = 0;
2253         if (!head_match || !remote_match) {
2254                 for (i = 1; i < o->head_idx; i++) {
2255                         if (stages[i] && stages[i] != o->df_conflict_entry) {
2256                                 keep_entry(stages[i], o);
2257                                 count++;
2258                                 break;
2259                         }
2260                 }
2261         }
2262 #if DBRT_DEBUG
2263         else {
2264                 fprintf(stderr, "read-tree: warning #16 detected\n");
2265                 show_stage_entry(stderr, "head   ", stages[head_match]);
2266                 show_stage_entry(stderr, "remote ", stages[remote_match]);
2267         }
2268 #endif
2269         if (head) { count += keep_entry(head, o); }
2270         if (remote) { count += keep_entry(remote, o); }
2271         return count;
2272 }
2273
2274 /*
2275  * Two-way merge.
2276  *
2277  * The rule is to "carry forward" what is in the index without losing
2278  * information across a "fast-forward", favoring a successful merge
2279  * over a merge failure when it makes sense.  For details of the
2280  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
2281  *
2282  */
2283 int twoway_merge(const struct cache_entry * const *src,
2284                  struct unpack_trees_options *o)
2285 {
2286         const struct cache_entry *current = src[0];
2287         const struct cache_entry *oldtree = src[1];
2288         const struct cache_entry *newtree = src[2];
2289
2290         if (o->merge_size != 2)
2291                 return error("Cannot do a twoway merge of %d trees",
2292                              o->merge_size);
2293
2294         if (oldtree == o->df_conflict_entry)
2295                 oldtree = NULL;
2296         if (newtree == o->df_conflict_entry)
2297                 newtree = NULL;
2298
2299         if (current) {
2300                 if (current->ce_flags & CE_CONFLICTED) {
2301                         if (same(oldtree, newtree) || o->reset) {
2302                                 if (!newtree)
2303                                         return deleted_entry(current, current, o);
2304                                 else
2305                                         return merged_entry(newtree, current, o);
2306                         }
2307                         return reject_merge(current, o);
2308                 } else if ((!oldtree && !newtree) || /* 4 and 5 */
2309                          (!oldtree && newtree &&
2310                           same(current, newtree)) || /* 6 and 7 */
2311                          (oldtree && newtree &&
2312                           same(oldtree, newtree)) || /* 14 and 15 */
2313                          (oldtree && newtree &&
2314                           !same(oldtree, newtree) && /* 18 and 19 */
2315                           same(current, newtree))) {
2316                         return keep_entry(current, o);
2317                 } else if (oldtree && !newtree && same(current, oldtree)) {
2318                         /* 10 or 11 */
2319                         return deleted_entry(oldtree, current, o);
2320                 } else if (oldtree && newtree &&
2321                          same(current, oldtree) && !same(current, newtree)) {
2322                         /* 20 or 21 */
2323                         return merged_entry(newtree, current, o);
2324                 } else
2325                         return reject_merge(current, o);
2326         }
2327         else if (newtree) {
2328                 if (oldtree && !o->initial_checkout) {
2329                         /*
2330                          * deletion of the path was staged;
2331                          */
2332                         if (same(oldtree, newtree))
2333                                 return 1;
2334                         return reject_merge(oldtree, o);
2335                 }
2336                 return merged_entry(newtree, current, o);
2337         }
2338         return deleted_entry(oldtree, current, o);
2339 }
2340
2341 /*
2342  * Bind merge.
2343  *
2344  * Keep the index entries at stage0, collapse stage1 but make sure
2345  * stage0 does not have anything there.
2346  */
2347 int bind_merge(const struct cache_entry * const *src,
2348                struct unpack_trees_options *o)
2349 {
2350         const struct cache_entry *old = src[0];
2351         const struct cache_entry *a = src[1];
2352
2353         if (o->merge_size != 1)
2354                 return error("Cannot do a bind merge of %d trees",
2355                              o->merge_size);
2356         if (a && old)
2357                 return o->quiet ? -1 :
2358                         error(ERRORMSG(o, ERROR_BIND_OVERLAP),
2359                               super_prefixed(a->name),
2360                               super_prefixed(old->name));
2361         if (!a)
2362                 return keep_entry(old, o);
2363         else
2364                 return merged_entry(a, NULL, o);
2365 }
2366
2367 /*
2368  * One-way merge.
2369  *
2370  * The rule is:
2371  * - take the stat information from stage0, take the data from stage1
2372  */
2373 int oneway_merge(const struct cache_entry * const *src,
2374                  struct unpack_trees_options *o)
2375 {
2376         const struct cache_entry *old = src[0];
2377         const struct cache_entry *a = src[1];
2378
2379         if (o->merge_size != 1)
2380                 return error("Cannot do a oneway merge of %d trees",
2381                              o->merge_size);
2382
2383         if (!a || a == o->df_conflict_entry)
2384                 return deleted_entry(old, old, o);
2385
2386         if (old && same(old, a)) {
2387                 int update = 0;
2388                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
2389                         struct stat st;
2390                         if (lstat(old->name, &st) ||
2391                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
2392                                 update |= CE_UPDATE;
2393                 }
2394                 if (o->update && S_ISGITLINK(old->ce_mode) &&
2395                     should_update_submodules() && !verify_uptodate(old, o))
2396                         update |= CE_UPDATE;
2397                 add_entry(o, old, update, CE_STAGEMASK);
2398                 return 0;
2399         }
2400         return merged_entry(a, old, o);
2401 }