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