Merge branch 'ls/p4-lfs'
[git] / unpack-trees.c
1 #define NO_THE_INDEX_COMPATIBILITY_MACROS
2 #include "cache.h"
3 #include "dir.h"
4 #include "tree.h"
5 #include "tree-walk.h"
6 #include "cache-tree.h"
7 #include "unpack-trees.h"
8 #include "progress.h"
9 #include "refs.h"
10 #include "attr.h"
11 #include "split-index.h"
12 #include "dir.h"
13
14 /*
15  * Error messages expected by scripts out of plumbing commands such as
16  * read-tree.  Non-scripted Porcelain is not required to use these messages
17  * and in fact are encouraged to reword them to better suit their particular
18  * situation better.  See how "git checkout" and "git merge" replaces
19  * them using setup_unpack_trees_porcelain(), for example.
20  */
21 static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
22         /* ERROR_WOULD_OVERWRITE */
23         "Entry '%s' would be overwritten by merge. Cannot merge.",
24
25         /* ERROR_NOT_UPTODATE_FILE */
26         "Entry '%s' not uptodate. Cannot merge.",
27
28         /* ERROR_NOT_UPTODATE_DIR */
29         "Updating '%s' would lose untracked files in it",
30
31         /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
32         "Untracked working tree file '%s' would be overwritten by merge.",
33
34         /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
35         "Untracked working tree file '%s' would be removed by merge.",
36
37         /* ERROR_BIND_OVERLAP */
38         "Entry '%s' overlaps with '%s'.  Cannot bind.",
39
40         /* ERROR_SPARSE_NOT_UPTODATE_FILE */
41         "Entry '%s' not uptodate. Cannot update sparse checkout.",
42
43         /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
44         "Working tree file '%s' would be overwritten by sparse checkout update.",
45
46         /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
47         "Working tree file '%s' would be removed by sparse checkout update.",
48 };
49
50 #define ERRORMSG(o,type) \
51         ( ((o) && (o)->msgs[(type)]) \
52           ? ((o)->msgs[(type)])      \
53           : (unpack_plumbing_errors[(type)]) )
54
55 void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
56                                   const char *cmd)
57 {
58         int i;
59         const char **msgs = opts->msgs;
60         const char *msg;
61
62         if (!strcmp(cmd, "checkout"))
63                 msg = advice_commit_before_merge
64                       ? _("Your local changes to the following files would be overwritten by checkout:\n%%s"
65                           "Please commit your changes or stash them before you switch branches.")
66                       : _("Your local changes to the following files would be overwritten by checkout:\n%%s");
67         else if (!strcmp(cmd, "merge"))
68                 msg = advice_commit_before_merge
69                       ? _("Your local changes to the following files would be overwritten by merge:\n%%s"
70                           "Please commit your changes or stash them before you merge.")
71                       : _("Your local changes to the following files would be overwritten by merge:\n%%s");
72         else
73                 msg = advice_commit_before_merge
74                       ? _("Your local changes to the following files would be overwritten by %s:\n%%s"
75                           "Please commit your changes or stash them before you %s.")
76                       : _("Your local changes to the following files would be overwritten by %s:\n%%s");
77         msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
78                 xstrfmt(msg, cmd, cmd);
79
80         msgs[ERROR_NOT_UPTODATE_DIR] =
81                 _("Updating the following directories would lose untracked files in them:\n%s");
82
83         if (!strcmp(cmd, "checkout"))
84                 msg = advice_commit_before_merge
85                       ? _("The following untracked working tree files would be removed by checkout:\n%%s"
86                           "Please move or remove them before you switch branches.")
87                       : _("The following untracked working tree files would be removed by checkout:\n%%s");
88         else if (!strcmp(cmd, "merge"))
89                 msg = advice_commit_before_merge
90                       ? _("The following untracked working tree files would be removed by merge:\n%%s"
91                           "Please move or remove them before you merge.")
92                       : _("The following untracked working tree files would be removed by merge:\n%%s");
93         else
94                 msg = advice_commit_before_merge
95                       ? _("The following untracked working tree files would be removed by %s:\n%%s"
96                           "Please move or remove them before you %s.")
97                       : _("The following untracked working tree files would be removed by %s:\n%%s");
98         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = xstrfmt(msg, cmd, cmd);
99
100         if (!strcmp(cmd, "checkout"))
101                 msg = advice_commit_before_merge
102                       ? _("The following untracked working tree files would be overwritten by checkout:\n%%s"
103                           "Please move or remove them before you switch branches.")
104                       : _("The following untracked working tree files would be overwritten by checkout:\n%%s");
105         else if (!strcmp(cmd, "merge"))
106                 msg = advice_commit_before_merge
107                       ? _("The following untracked working tree files would be overwritten by merge:\n%%s"
108                           "Please move or remove them before you merge.")
109                       : _("The following untracked working tree files would be overwritten by merge:\n%%s");
110         else
111                 msg = advice_commit_before_merge
112                       ? _("The following untracked working tree files would be overwritten by %s:\n%%s"
113                           "Please move or remove them before you %s.")
114                       : _("The following untracked working tree files would be overwritten by %s:\n%%s");
115         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = xstrfmt(msg, cmd, cmd);
116
117         /*
118          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
119          * cannot easily display it as a list.
120          */
121         msgs[ERROR_BIND_OVERLAP] = _("Entry '%s' overlaps with '%s'.  Cannot bind.");
122
123         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
124                 _("Cannot update sparse checkout: the following entries are not up-to-date:\n%s");
125         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
126                 _("The following working tree files would be overwritten by sparse checkout update:\n%s");
127         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
128                 _("The following working tree files would be removed by sparse checkout update:\n%s");
129
130         opts->show_all_errors = 1;
131         /* rejected paths may not have a static buffer */
132         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
133                 opts->unpack_rejects[i].strdup_strings = 1;
134 }
135
136 static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
137                          unsigned int set, unsigned int clear)
138 {
139         clear |= CE_HASHED;
140
141         if (set & CE_REMOVE)
142                 set |= CE_WT_REMOVE;
143
144         ce->ce_flags = (ce->ce_flags & ~clear) | set;
145         return add_index_entry(&o->result, ce,
146                                ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
147 }
148
149 static struct cache_entry *dup_entry(const struct cache_entry *ce)
150 {
151         unsigned int size = ce_size(ce);
152         struct cache_entry *new = xmalloc(size);
153
154         memcpy(new, ce, size);
155         return new;
156 }
157
158 static void add_entry(struct unpack_trees_options *o,
159                       const struct cache_entry *ce,
160                       unsigned int set, unsigned int clear)
161 {
162         do_add_entry(o, dup_entry(ce), set, clear);
163 }
164
165 /*
166  * add error messages on path <path>
167  * corresponding to the type <e> with the message <msg>
168  * indicating if it should be display in porcelain or not
169  */
170 static int add_rejected_path(struct unpack_trees_options *o,
171                              enum unpack_trees_error_types e,
172                              const char *path)
173 {
174         if (!o->show_all_errors)
175                 return error(ERRORMSG(o, e), path);
176
177         /*
178          * Otherwise, insert in a list for future display by
179          * display_error_msgs()
180          */
181         string_list_append(&o->unpack_rejects[e], path);
182         return -1;
183 }
184
185 /*
186  * display all the error messages stored in a nice way
187  */
188 static void display_error_msgs(struct unpack_trees_options *o)
189 {
190         int e, i;
191         int something_displayed = 0;
192         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
193                 struct string_list *rejects = &o->unpack_rejects[e];
194                 if (rejects->nr > 0) {
195                         struct strbuf path = STRBUF_INIT;
196                         something_displayed = 1;
197                         for (i = 0; i < rejects->nr; i++)
198                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
199                         error(ERRORMSG(o, e), path.buf);
200                         strbuf_release(&path);
201                 }
202                 string_list_clear(rejects, 0);
203         }
204         if (something_displayed)
205                 fprintf(stderr, _("Aborting\n"));
206 }
207
208 /*
209  * Unlink the last component and schedule the leading directories for
210  * removal, such that empty directories get removed.
211  */
212 static void unlink_entry(const struct cache_entry *ce)
213 {
214         if (!check_leading_path(ce->name, ce_namelen(ce)))
215                 return;
216         if (remove_or_warn(ce->ce_mode, ce->name))
217                 return;
218         schedule_dir_for_removal(ce->name, ce_namelen(ce));
219 }
220
221 static int check_updates(struct unpack_trees_options *o,
222                          const struct checkout *state)
223 {
224         unsigned cnt = 0, total = 0;
225         struct progress *progress = NULL;
226         struct index_state *index = &o->result;
227         int i;
228         int errs = 0;
229
230         if (o->update && o->verbose_update) {
231                 for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
232                         const struct cache_entry *ce = index->cache[cnt];
233                         if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
234                                 total++;
235                 }
236
237                 progress = start_progress_delay(_("Checking out files"),
238                                                 total, 50, 1);
239                 cnt = 0;
240         }
241
242         if (o->update)
243                 git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
244         for (i = 0; i < index->cache_nr; i++) {
245                 const struct cache_entry *ce = index->cache[i];
246
247                 if (ce->ce_flags & CE_WT_REMOVE) {
248                         display_progress(progress, ++cnt);
249                         if (o->update && !o->dry_run)
250                                 unlink_entry(ce);
251                         continue;
252                 }
253         }
254         remove_marked_cache_entries(&o->result);
255         remove_scheduled_dirs();
256
257         for (i = 0; i < index->cache_nr; i++) {
258                 struct cache_entry *ce = index->cache[i];
259
260                 if (ce->ce_flags & CE_UPDATE) {
261                         if (ce->ce_flags & CE_WT_REMOVE)
262                                 die("BUG: both update and delete flags are set on %s",
263                                     ce->name);
264                         display_progress(progress, ++cnt);
265                         ce->ce_flags &= ~CE_UPDATE;
266                         if (o->update && !o->dry_run) {
267                                 errs |= checkout_entry(ce, state, NULL);
268                         }
269                 }
270         }
271         stop_progress(&progress);
272         if (o->update)
273                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
274         return errs != 0;
275 }
276
277 static int verify_uptodate_sparse(const struct cache_entry *ce,
278                                   struct unpack_trees_options *o);
279 static int verify_absent_sparse(const struct cache_entry *ce,
280                                 enum unpack_trees_error_types,
281                                 struct unpack_trees_options *o);
282
283 static int apply_sparse_checkout(struct index_state *istate,
284                                  struct cache_entry *ce,
285                                  struct unpack_trees_options *o)
286 {
287         int was_skip_worktree = ce_skip_worktree(ce);
288
289         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
290                 ce->ce_flags |= CE_SKIP_WORKTREE;
291         else
292                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
293         if (was_skip_worktree != ce_skip_worktree(ce)) {
294                 ce->ce_flags |= CE_UPDATE_IN_BASE;
295                 istate->cache_changed |= CE_ENTRY_CHANGED;
296         }
297
298         /*
299          * if (!was_skip_worktree && !ce_skip_worktree()) {
300          *      This is perfectly normal. Move on;
301          * }
302          */
303
304         /*
305          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
306          * area as a result of ce_skip_worktree() shortcuts in
307          * verify_absent() and verify_uptodate().
308          * Make sure they don't modify worktree if they are already
309          * outside checkout area
310          */
311         if (was_skip_worktree && ce_skip_worktree(ce)) {
312                 ce->ce_flags &= ~CE_UPDATE;
313
314                 /*
315                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
316                  * on to get that file removed from both index and worktree.
317                  * If that file is already outside worktree area, don't
318                  * bother remove it.
319                  */
320                 if (ce->ce_flags & CE_REMOVE)
321                         ce->ce_flags &= ~CE_WT_REMOVE;
322         }
323
324         if (!was_skip_worktree && ce_skip_worktree(ce)) {
325                 /*
326                  * If CE_UPDATE is set, verify_uptodate() must be called already
327                  * also stat info may have lost after merged_entry() so calling
328                  * verify_uptodate() again may fail
329                  */
330                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
331                         return -1;
332                 ce->ce_flags |= CE_WT_REMOVE;
333                 ce->ce_flags &= ~CE_UPDATE;
334         }
335         if (was_skip_worktree && !ce_skip_worktree(ce)) {
336                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
337                         return -1;
338                 ce->ce_flags |= CE_UPDATE;
339         }
340         return 0;
341 }
342
343 static inline int call_unpack_fn(const struct cache_entry * const *src,
344                                  struct unpack_trees_options *o)
345 {
346         int ret = o->fn(src, o);
347         if (ret > 0)
348                 ret = 0;
349         return ret;
350 }
351
352 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
353 {
354         ce->ce_flags |= CE_UNPACKED;
355
356         if (o->cache_bottom < o->src_index->cache_nr &&
357             o->src_index->cache[o->cache_bottom] == ce) {
358                 int bottom = o->cache_bottom;
359                 while (bottom < o->src_index->cache_nr &&
360                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
361                         bottom++;
362                 o->cache_bottom = bottom;
363         }
364 }
365
366 static void mark_all_ce_unused(struct index_state *index)
367 {
368         int i;
369         for (i = 0; i < index->cache_nr; i++)
370                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
371 }
372
373 static int locate_in_src_index(const struct cache_entry *ce,
374                                struct unpack_trees_options *o)
375 {
376         struct index_state *index = o->src_index;
377         int len = ce_namelen(ce);
378         int pos = index_name_pos(index, ce->name, len);
379         if (pos < 0)
380                 pos = -1 - pos;
381         return pos;
382 }
383
384 /*
385  * We call unpack_index_entry() with an unmerged cache entry
386  * only in diff-index, and it wants a single callback.  Skip
387  * the other unmerged entry with the same name.
388  */
389 static void mark_ce_used_same_name(struct cache_entry *ce,
390                                    struct unpack_trees_options *o)
391 {
392         struct index_state *index = o->src_index;
393         int len = ce_namelen(ce);
394         int pos;
395
396         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
397                 struct cache_entry *next = index->cache[pos];
398                 if (len != ce_namelen(next) ||
399                     memcmp(ce->name, next->name, len))
400                         break;
401                 mark_ce_used(next, o);
402         }
403 }
404
405 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
406 {
407         const struct index_state *index = o->src_index;
408         int pos = o->cache_bottom;
409
410         while (pos < index->cache_nr) {
411                 struct cache_entry *ce = index->cache[pos];
412                 if (!(ce->ce_flags & CE_UNPACKED))
413                         return ce;
414                 pos++;
415         }
416         return NULL;
417 }
418
419 static void add_same_unmerged(const struct cache_entry *ce,
420                               struct unpack_trees_options *o)
421 {
422         struct index_state *index = o->src_index;
423         int len = ce_namelen(ce);
424         int pos = index_name_pos(index, ce->name, len);
425
426         if (0 <= pos)
427                 die("programming error in a caller of mark_ce_used_same_name");
428         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
429                 struct cache_entry *next = index->cache[pos];
430                 if (len != ce_namelen(next) ||
431                     memcmp(ce->name, next->name, len))
432                         break;
433                 add_entry(o, next, 0, 0);
434                 mark_ce_used(next, o);
435         }
436 }
437
438 static int unpack_index_entry(struct cache_entry *ce,
439                               struct unpack_trees_options *o)
440 {
441         const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
442         int ret;
443
444         src[0] = ce;
445
446         mark_ce_used(ce, o);
447         if (ce_stage(ce)) {
448                 if (o->skip_unmerged) {
449                         add_entry(o, ce, 0, 0);
450                         return 0;
451                 }
452         }
453         ret = call_unpack_fn(src, o);
454         if (ce_stage(ce))
455                 mark_ce_used_same_name(ce, o);
456         return ret;
457 }
458
459 static int find_cache_pos(struct traverse_info *, const struct name_entry *);
460
461 static void restore_cache_bottom(struct traverse_info *info, int bottom)
462 {
463         struct unpack_trees_options *o = info->data;
464
465         if (o->diff_index_cached)
466                 return;
467         o->cache_bottom = bottom;
468 }
469
470 static int switch_cache_bottom(struct traverse_info *info)
471 {
472         struct unpack_trees_options *o = info->data;
473         int ret, pos;
474
475         if (o->diff_index_cached)
476                 return 0;
477         ret = o->cache_bottom;
478         pos = find_cache_pos(info->prev, &info->name);
479
480         if (pos < -1)
481                 o->cache_bottom = -2 - pos;
482         else if (pos < 0)
483                 o->cache_bottom = o->src_index->cache_nr;
484         return ret;
485 }
486
487 static int traverse_trees_recursive(int n, unsigned long dirmask,
488                                     unsigned long df_conflicts,
489                                     struct name_entry *names,
490                                     struct traverse_info *info)
491 {
492         int i, ret, bottom;
493         struct tree_desc t[MAX_UNPACK_TREES];
494         void *buf[MAX_UNPACK_TREES];
495         struct traverse_info newinfo;
496         struct name_entry *p;
497
498         p = names;
499         while (!p->mode)
500                 p++;
501
502         newinfo = *info;
503         newinfo.prev = info;
504         newinfo.pathspec = info->pathspec;
505         newinfo.name = *p;
506         newinfo.pathlen += tree_entry_len(p) + 1;
507         newinfo.df_conflicts |= df_conflicts;
508
509         for (i = 0; i < n; i++, dirmask >>= 1) {
510                 const unsigned char *sha1 = NULL;
511                 if (dirmask & 1)
512                         sha1 = names[i].oid->hash;
513                 buf[i] = fill_tree_descriptor(t+i, sha1);
514         }
515
516         bottom = switch_cache_bottom(&newinfo);
517         ret = traverse_trees(n, t, &newinfo);
518         restore_cache_bottom(&newinfo, bottom);
519
520         for (i = 0; i < n; i++)
521                 free(buf[i]);
522
523         return ret;
524 }
525
526 /*
527  * Compare the traverse-path to the cache entry without actually
528  * having to generate the textual representation of the traverse
529  * path.
530  *
531  * NOTE! This *only* compares up to the size of the traverse path
532  * itself - the caller needs to do the final check for the cache
533  * entry having more data at the end!
534  */
535 static int do_compare_entry_piecewise(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
536 {
537         int len, pathlen, ce_len;
538         const char *ce_name;
539
540         if (info->prev) {
541                 int cmp = do_compare_entry_piecewise(ce, info->prev,
542                                                      &info->name);
543                 if (cmp)
544                         return cmp;
545         }
546         pathlen = info->pathlen;
547         ce_len = ce_namelen(ce);
548
549         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
550         if (ce_len < pathlen)
551                 return -1;
552
553         ce_len -= pathlen;
554         ce_name = ce->name + pathlen;
555
556         len = tree_entry_len(n);
557         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
558 }
559
560 static int do_compare_entry(const struct cache_entry *ce,
561                             const struct traverse_info *info,
562                             const struct name_entry *n)
563 {
564         int len, pathlen, ce_len;
565         const char *ce_name;
566         int cmp;
567
568         /*
569          * If we have not precomputed the traverse path, it is quicker
570          * to avoid doing so.  But if we have precomputed it,
571          * it is quicker to use the precomputed version.
572          */
573         if (!info->traverse_path)
574                 return do_compare_entry_piecewise(ce, info, n);
575
576         cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
577         if (cmp)
578                 return cmp;
579
580         pathlen = info->pathlen;
581         ce_len = ce_namelen(ce);
582
583         if (ce_len < pathlen)
584                 return -1;
585
586         ce_len -= pathlen;
587         ce_name = ce->name + pathlen;
588
589         len = tree_entry_len(n);
590         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
591 }
592
593 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
594 {
595         int cmp = do_compare_entry(ce, info, n);
596         if (cmp)
597                 return cmp;
598
599         /*
600          * Even if the beginning compared identically, the ce should
601          * compare as bigger than a directory leading up to it!
602          */
603         return ce_namelen(ce) > traverse_path_len(info, n);
604 }
605
606 static int ce_in_traverse_path(const struct cache_entry *ce,
607                                const struct traverse_info *info)
608 {
609         if (!info->prev)
610                 return 1;
611         if (do_compare_entry(ce, info->prev, &info->name))
612                 return 0;
613         /*
614          * If ce (blob) is the same name as the path (which is a tree
615          * we will be descending into), it won't be inside it.
616          */
617         return (info->pathlen < ce_namelen(ce));
618 }
619
620 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
621 {
622         int len = traverse_path_len(info, n);
623         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
624
625         ce->ce_mode = create_ce_mode(n->mode);
626         ce->ce_flags = create_ce_flags(stage);
627         ce->ce_namelen = len;
628         oidcpy(&ce->oid, n->oid);
629         make_traverse_path(ce->name, info, n);
630
631         return ce;
632 }
633
634 static int unpack_nondirectories(int n, unsigned long mask,
635                                  unsigned long dirmask,
636                                  struct cache_entry **src,
637                                  const struct name_entry *names,
638                                  const struct traverse_info *info)
639 {
640         int i;
641         struct unpack_trees_options *o = info->data;
642         unsigned long conflicts = info->df_conflicts | dirmask;
643
644         /* Do we have *only* directories? Nothing to do */
645         if (mask == dirmask && !src[0])
646                 return 0;
647
648         /*
649          * Ok, we've filled in up to any potential index entry in src[0],
650          * now do the rest.
651          */
652         for (i = 0; i < n; i++) {
653                 int stage;
654                 unsigned int bit = 1ul << i;
655                 if (conflicts & bit) {
656                         src[i + o->merge] = o->df_conflict_entry;
657                         continue;
658                 }
659                 if (!(mask & bit))
660                         continue;
661                 if (!o->merge)
662                         stage = 0;
663                 else if (i + 1 < o->head_idx)
664                         stage = 1;
665                 else if (i + 1 > o->head_idx)
666                         stage = 3;
667                 else
668                         stage = 2;
669                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
670         }
671
672         if (o->merge) {
673                 int rc = call_unpack_fn((const struct cache_entry * const *)src,
674                                         o);
675                 for (i = 0; i < n; i++) {
676                         struct cache_entry *ce = src[i + o->merge];
677                         if (ce != o->df_conflict_entry)
678                                 free(ce);
679                 }
680                 return rc;
681         }
682
683         for (i = 0; i < n; i++)
684                 if (src[i] && src[i] != o->df_conflict_entry)
685                         if (do_add_entry(o, src[i], 0, 0))
686                                 return -1;
687
688         return 0;
689 }
690
691 static int unpack_failed(struct unpack_trees_options *o, const char *message)
692 {
693         discard_index(&o->result);
694         if (!o->gently && !o->exiting_early) {
695                 if (message)
696                         return error("%s", message);
697                 return -1;
698         }
699         return -1;
700 }
701
702 /*
703  * The tree traversal is looking at name p.  If we have a matching entry,
704  * return it.  If name p is a directory in the index, do not return
705  * anything, as we will want to match it when the traversal descends into
706  * the directory.
707  */
708 static int find_cache_pos(struct traverse_info *info,
709                           const struct name_entry *p)
710 {
711         int pos;
712         struct unpack_trees_options *o = info->data;
713         struct index_state *index = o->src_index;
714         int pfxlen = info->pathlen;
715         int p_len = tree_entry_len(p);
716
717         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
718                 const struct cache_entry *ce = index->cache[pos];
719                 const char *ce_name, *ce_slash;
720                 int cmp, ce_len;
721
722                 if (ce->ce_flags & CE_UNPACKED) {
723                         /*
724                          * cache_bottom entry is already unpacked, so
725                          * we can never match it; don't check it
726                          * again.
727                          */
728                         if (pos == o->cache_bottom)
729                                 ++o->cache_bottom;
730                         continue;
731                 }
732                 if (!ce_in_traverse_path(ce, info)) {
733                         /*
734                          * Check if we can skip future cache checks
735                          * (because we're already past all possible
736                          * entries in the traverse path).
737                          */
738                         if (info->traverse_path) {
739                                 if (strncmp(ce->name, info->traverse_path,
740                                             info->pathlen) > 0)
741                                         break;
742                         }
743                         continue;
744                 }
745                 ce_name = ce->name + pfxlen;
746                 ce_slash = strchr(ce_name, '/');
747                 if (ce_slash)
748                         ce_len = ce_slash - ce_name;
749                 else
750                         ce_len = ce_namelen(ce) - pfxlen;
751                 cmp = name_compare(p->path, p_len, ce_name, ce_len);
752                 /*
753                  * Exact match; if we have a directory we need to
754                  * delay returning it.
755                  */
756                 if (!cmp)
757                         return ce_slash ? -2 - pos : pos;
758                 if (0 < cmp)
759                         continue; /* keep looking */
760                 /*
761                  * ce_name sorts after p->path; could it be that we
762                  * have files under p->path directory in the index?
763                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
764                  * have "t/a" in the index.
765                  */
766                 if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
767                     ce_name[p_len] < '/')
768                         continue; /* keep looking */
769                 break;
770         }
771         return -1;
772 }
773
774 static struct cache_entry *find_cache_entry(struct traverse_info *info,
775                                             const struct name_entry *p)
776 {
777         int pos = find_cache_pos(info, p);
778         struct unpack_trees_options *o = info->data;
779
780         if (0 <= pos)
781                 return o->src_index->cache[pos];
782         else
783                 return NULL;
784 }
785
786 static void debug_path(struct traverse_info *info)
787 {
788         if (info->prev) {
789                 debug_path(info->prev);
790                 if (*info->prev->name.path)
791                         putchar('/');
792         }
793         printf("%s", info->name.path);
794 }
795
796 static void debug_name_entry(int i, struct name_entry *n)
797 {
798         printf("ent#%d %06o %s\n", i,
799                n->path ? n->mode : 0,
800                n->path ? n->path : "(missing)");
801 }
802
803 static void debug_unpack_callback(int n,
804                                   unsigned long mask,
805                                   unsigned long dirmask,
806                                   struct name_entry *names,
807                                   struct traverse_info *info)
808 {
809         int i;
810         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
811                mask, dirmask, n);
812         debug_path(info);
813         putchar('\n');
814         for (i = 0; i < n; i++)
815                 debug_name_entry(i, names + i);
816 }
817
818 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
819 {
820         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
821         struct unpack_trees_options *o = info->data;
822         const struct name_entry *p = names;
823
824         /* Find first entry with a real name (we could use "mask" too) */
825         while (!p->mode)
826                 p++;
827
828         if (o->debug_unpack)
829                 debug_unpack_callback(n, mask, dirmask, names, info);
830
831         /* Are we supposed to look at the index too? */
832         if (o->merge) {
833                 while (1) {
834                         int cmp;
835                         struct cache_entry *ce;
836
837                         if (o->diff_index_cached)
838                                 ce = next_cache_entry(o);
839                         else
840                                 ce = find_cache_entry(info, p);
841
842                         if (!ce)
843                                 break;
844                         cmp = compare_entry(ce, info, p);
845                         if (cmp < 0) {
846                                 if (unpack_index_entry(ce, o) < 0)
847                                         return unpack_failed(o, NULL);
848                                 continue;
849                         }
850                         if (!cmp) {
851                                 if (ce_stage(ce)) {
852                                         /*
853                                          * If we skip unmerged index
854                                          * entries, we'll skip this
855                                          * entry *and* the tree
856                                          * entries associated with it!
857                                          */
858                                         if (o->skip_unmerged) {
859                                                 add_same_unmerged(ce, o);
860                                                 return mask;
861                                         }
862                                 }
863                                 src[0] = ce;
864                         }
865                         break;
866                 }
867         }
868
869         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
870                 return -1;
871
872         if (o->merge && src[0]) {
873                 if (ce_stage(src[0]))
874                         mark_ce_used_same_name(src[0], o);
875                 else
876                         mark_ce_used(src[0], o);
877         }
878
879         /* Now handle any directories.. */
880         if (dirmask) {
881                 /* special case: "diff-index --cached" looking at a tree */
882                 if (o->diff_index_cached &&
883                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
884                         int matches;
885                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
886                                                                names, info);
887                         /*
888                          * Everything under the name matches; skip the
889                          * entire hierarchy.  diff_index_cached codepath
890                          * special cases D/F conflicts in such a way that
891                          * it does not do any look-ahead, so this is safe.
892                          */
893                         if (matches) {
894                                 o->cache_bottom += matches;
895                                 return mask;
896                         }
897                 }
898
899                 if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
900                                              names, info) < 0)
901                         return -1;
902                 return mask;
903         }
904
905         return mask;
906 }
907
908 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
909                             struct strbuf *prefix,
910                             int select_mask, int clear_mask,
911                             struct exclude_list *el, int defval);
912
913 /* Whole directory matching */
914 static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
915                               struct strbuf *prefix,
916                               char *basename,
917                               int select_mask, int clear_mask,
918                               struct exclude_list *el, int defval)
919 {
920         struct cache_entry **cache_end;
921         int dtype = DT_DIR;
922         int ret = is_excluded_from_list(prefix->buf, prefix->len,
923                                         basename, &dtype, el);
924         int rc;
925
926         strbuf_addch(prefix, '/');
927
928         /* If undecided, use matching result of parent dir in defval */
929         if (ret < 0)
930                 ret = defval;
931
932         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
933                 struct cache_entry *ce = *cache_end;
934                 if (strncmp(ce->name, prefix->buf, prefix->len))
935                         break;
936         }
937
938         /*
939          * TODO: check el, if there are no patterns that may conflict
940          * with ret (iow, we know in advance the incl/excl
941          * decision for the entire directory), clear flag here without
942          * calling clear_ce_flags_1(). That function will call
943          * the expensive is_excluded_from_list() on every entry.
944          */
945         rc = clear_ce_flags_1(cache, cache_end - cache,
946                               prefix,
947                               select_mask, clear_mask,
948                               el, ret);
949         strbuf_setlen(prefix, prefix->len - 1);
950         return rc;
951 }
952
953 /*
954  * Traverse the index, find every entry that matches according to
955  * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
956  * number of traversed entries.
957  *
958  * If select_mask is non-zero, only entries whose ce_flags has on of
959  * those bits enabled are traversed.
960  *
961  * cache        : pointer to an index entry
962  * prefix_len   : an offset to its path
963  *
964  * The current path ("prefix") including the trailing '/' is
965  *   cache[0]->name[0..(prefix_len-1)]
966  * Top level path has prefix_len zero.
967  */
968 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
969                             struct strbuf *prefix,
970                             int select_mask, int clear_mask,
971                             struct exclude_list *el, int defval)
972 {
973         struct cache_entry **cache_end = cache + nr;
974
975         /*
976          * Process all entries that have the given prefix and meet
977          * select_mask condition
978          */
979         while(cache != cache_end) {
980                 struct cache_entry *ce = *cache;
981                 const char *name, *slash;
982                 int len, dtype, ret;
983
984                 if (select_mask && !(ce->ce_flags & select_mask)) {
985                         cache++;
986                         continue;
987                 }
988
989                 if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
990                         break;
991
992                 name = ce->name + prefix->len;
993                 slash = strchr(name, '/');
994
995                 /* If it's a directory, try whole directory match first */
996                 if (slash) {
997                         int processed;
998
999                         len = slash - name;
1000                         strbuf_add(prefix, name, len);
1001
1002                         processed = clear_ce_flags_dir(cache, cache_end - cache,
1003                                                        prefix,
1004                                                        prefix->buf + prefix->len - len,
1005                                                        select_mask, clear_mask,
1006                                                        el, defval);
1007
1008                         /* clear_c_f_dir eats a whole dir already? */
1009                         if (processed) {
1010                                 cache += processed;
1011                                 strbuf_setlen(prefix, prefix->len - len);
1012                                 continue;
1013                         }
1014
1015                         strbuf_addch(prefix, '/');
1016                         cache += clear_ce_flags_1(cache, cache_end - cache,
1017                                                   prefix,
1018                                                   select_mask, clear_mask, el, defval);
1019                         strbuf_setlen(prefix, prefix->len - len - 1);
1020                         continue;
1021                 }
1022
1023                 /* Non-directory */
1024                 dtype = ce_to_dtype(ce);
1025                 ret = is_excluded_from_list(ce->name, ce_namelen(ce),
1026                                             name, &dtype, el);
1027                 if (ret < 0)
1028                         ret = defval;
1029                 if (ret > 0)
1030                         ce->ce_flags &= ~clear_mask;
1031                 cache++;
1032         }
1033         return nr - (cache_end - cache);
1034 }
1035
1036 static int clear_ce_flags(struct cache_entry **cache, int nr,
1037                             int select_mask, int clear_mask,
1038                             struct exclude_list *el)
1039 {
1040         static struct strbuf prefix = STRBUF_INIT;
1041
1042         strbuf_reset(&prefix);
1043
1044         return clear_ce_flags_1(cache, nr,
1045                                 &prefix,
1046                                 select_mask, clear_mask,
1047                                 el, 0);
1048 }
1049
1050 /*
1051  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1052  */
1053 static void mark_new_skip_worktree(struct exclude_list *el,
1054                                    struct index_state *the_index,
1055                                    int select_flag, int skip_wt_flag)
1056 {
1057         int i;
1058
1059         /*
1060          * 1. Pretend the narrowest worktree: only unmerged entries
1061          * are checked out
1062          */
1063         for (i = 0; i < the_index->cache_nr; i++) {
1064                 struct cache_entry *ce = the_index->cache[i];
1065
1066                 if (select_flag && !(ce->ce_flags & select_flag))
1067                         continue;
1068
1069                 if (!ce_stage(ce))
1070                         ce->ce_flags |= skip_wt_flag;
1071                 else
1072                         ce->ce_flags &= ~skip_wt_flag;
1073         }
1074
1075         /*
1076          * 2. Widen worktree according to sparse-checkout file.
1077          * Matched entries will have skip_wt_flag cleared (i.e. "in")
1078          */
1079         clear_ce_flags(the_index->cache, the_index->cache_nr,
1080                        select_flag, skip_wt_flag, el);
1081 }
1082
1083 static int verify_absent(const struct cache_entry *,
1084                          enum unpack_trees_error_types,
1085                          struct unpack_trees_options *);
1086 /*
1087  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1088  * resulting index, -2 on failure to reflect the changes to the work tree.
1089  *
1090  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1091  */
1092 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1093 {
1094         int i, ret;
1095         static struct cache_entry *dfc;
1096         struct exclude_list el;
1097         struct checkout state = CHECKOUT_INIT;
1098
1099         if (len > MAX_UNPACK_TREES)
1100                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1101         state.force = 1;
1102         state.quiet = 1;
1103         state.refresh_cache = 1;
1104         state.istate = &o->result;
1105
1106         memset(&el, 0, sizeof(el));
1107         if (!core_apply_sparse_checkout || !o->update)
1108                 o->skip_sparse_checkout = 1;
1109         if (!o->skip_sparse_checkout) {
1110                 char *sparse = git_pathdup("info/sparse-checkout");
1111                 if (add_excludes_from_file_to_list(sparse, "", 0, &el, 0) < 0)
1112                         o->skip_sparse_checkout = 1;
1113                 else
1114                         o->el = &el;
1115                 free(sparse);
1116         }
1117
1118         memset(&o->result, 0, sizeof(o->result));
1119         o->result.initialized = 1;
1120         o->result.timestamp.sec = o->src_index->timestamp.sec;
1121         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1122         o->result.version = o->src_index->version;
1123         o->result.split_index = o->src_index->split_index;
1124         if (o->result.split_index)
1125                 o->result.split_index->refcount++;
1126         hashcpy(o->result.sha1, o->src_index->sha1);
1127         o->merge_size = len;
1128         mark_all_ce_unused(o->src_index);
1129
1130         /*
1131          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1132          */
1133         if (!o->skip_sparse_checkout)
1134                 mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1135
1136         if (!dfc)
1137                 dfc = xcalloc(1, cache_entry_size(0));
1138         o->df_conflict_entry = dfc;
1139
1140         if (len) {
1141                 const char *prefix = o->prefix ? o->prefix : "";
1142                 struct traverse_info info;
1143
1144                 setup_traverse_info(&info, prefix);
1145                 info.fn = unpack_callback;
1146                 info.data = o;
1147                 info.show_all_errors = o->show_all_errors;
1148                 info.pathspec = o->pathspec;
1149
1150                 if (o->prefix) {
1151                         /*
1152                          * Unpack existing index entries that sort before the
1153                          * prefix the tree is spliced into.  Note that o->merge
1154                          * is always true in this case.
1155                          */
1156                         while (1) {
1157                                 struct cache_entry *ce = next_cache_entry(o);
1158                                 if (!ce)
1159                                         break;
1160                                 if (ce_in_traverse_path(ce, &info))
1161                                         break;
1162                                 if (unpack_index_entry(ce, o) < 0)
1163                                         goto return_failed;
1164                         }
1165                 }
1166
1167                 if (traverse_trees(len, t, &info) < 0)
1168                         goto return_failed;
1169         }
1170
1171         /* Any left-over entries in the index? */
1172         if (o->merge) {
1173                 while (1) {
1174                         struct cache_entry *ce = next_cache_entry(o);
1175                         if (!ce)
1176                                 break;
1177                         if (unpack_index_entry(ce, o) < 0)
1178                                 goto return_failed;
1179                 }
1180         }
1181         mark_all_ce_unused(o->src_index);
1182
1183         if (o->trivial_merges_only && o->nontrivial_merge) {
1184                 ret = unpack_failed(o, "Merge requires file-level merging");
1185                 goto done;
1186         }
1187
1188         if (!o->skip_sparse_checkout) {
1189                 int empty_worktree = 1;
1190
1191                 /*
1192                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1193                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1194                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1195                  */
1196                 mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1197
1198                 ret = 0;
1199                 for (i = 0; i < o->result.cache_nr; i++) {
1200                         struct cache_entry *ce = o->result.cache[i];
1201
1202                         /*
1203                          * Entries marked with CE_ADDED in merged_entry() do not have
1204                          * verify_absent() check (the check is effectively disabled
1205                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1206                          *
1207                          * Do the real check now because we have had
1208                          * correct CE_NEW_SKIP_WORKTREE
1209                          */
1210                         if (ce->ce_flags & CE_ADDED &&
1211                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1212                                 if (!o->show_all_errors)
1213                                         goto return_failed;
1214                                 ret = -1;
1215                         }
1216
1217                         if (apply_sparse_checkout(&o->result, ce, o)) {
1218                                 if (!o->show_all_errors)
1219                                         goto return_failed;
1220                                 ret = -1;
1221                         }
1222                         if (!ce_skip_worktree(ce))
1223                                 empty_worktree = 0;
1224
1225                 }
1226                 if (ret < 0)
1227                         goto return_failed;
1228                 /*
1229                  * Sparse checkout is meant to narrow down checkout area
1230                  * but it does not make sense to narrow down to empty working
1231                  * tree. This is usually a mistake in sparse checkout rules.
1232                  * Do not allow users to do that.
1233                  */
1234                 if (o->result.cache_nr && empty_worktree) {
1235                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1236                         goto done;
1237                 }
1238         }
1239
1240         o->src_index = NULL;
1241         ret = check_updates(o, &state) ? (-2) : 0;
1242         if (o->dst_index) {
1243                 if (!ret) {
1244                         if (!o->result.cache_tree)
1245                                 o->result.cache_tree = cache_tree();
1246                         if (!cache_tree_fully_valid(o->result.cache_tree))
1247                                 cache_tree_update(&o->result,
1248                                                   WRITE_TREE_SILENT |
1249                                                   WRITE_TREE_REPAIR);
1250                 }
1251                 discard_index(o->dst_index);
1252                 *o->dst_index = o->result;
1253         } else {
1254                 discard_index(&o->result);
1255         }
1256
1257 done:
1258         clear_exclude_list(&el);
1259         return ret;
1260
1261 return_failed:
1262         if (o->show_all_errors)
1263                 display_error_msgs(o);
1264         mark_all_ce_unused(o->src_index);
1265         ret = unpack_failed(o, NULL);
1266         if (o->exiting_early)
1267                 ret = 0;
1268         goto done;
1269 }
1270
1271 /* Here come the merge functions */
1272
1273 static int reject_merge(const struct cache_entry *ce,
1274                         struct unpack_trees_options *o)
1275 {
1276         return o->gently ? -1 :
1277                 add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1278 }
1279
1280 static int same(const struct cache_entry *a, const struct cache_entry *b)
1281 {
1282         if (!!a != !!b)
1283                 return 0;
1284         if (!a && !b)
1285                 return 1;
1286         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1287                 return 0;
1288         return a->ce_mode == b->ce_mode &&
1289                !oidcmp(&a->oid, &b->oid);
1290 }
1291
1292
1293 /*
1294  * When a CE gets turned into an unmerged entry, we
1295  * want it to be up-to-date
1296  */
1297 static int verify_uptodate_1(const struct cache_entry *ce,
1298                              struct unpack_trees_options *o,
1299                              enum unpack_trees_error_types error_type)
1300 {
1301         struct stat st;
1302
1303         if (o->index_only)
1304                 return 0;
1305
1306         /*
1307          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1308          * if this entry is truly up-to-date because this file may be
1309          * overwritten.
1310          */
1311         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1312                 ; /* keep checking */
1313         else if (o->reset || ce_uptodate(ce))
1314                 return 0;
1315
1316         if (!lstat(ce->name, &st)) {
1317                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1318                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1319                 if (!changed)
1320                         return 0;
1321                 /*
1322                  * NEEDSWORK: the current default policy is to allow
1323                  * submodule to be out of sync wrt the superproject
1324                  * index.  This needs to be tightened later for
1325                  * submodules that are marked to be automatically
1326                  * checked out.
1327                  */
1328                 if (S_ISGITLINK(ce->ce_mode))
1329                         return 0;
1330                 errno = 0;
1331         }
1332         if (errno == ENOENT)
1333                 return 0;
1334         return o->gently ? -1 :
1335                 add_rejected_path(o, error_type, ce->name);
1336 }
1337
1338 static int verify_uptodate(const struct cache_entry *ce,
1339                            struct unpack_trees_options *o)
1340 {
1341         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1342                 return 0;
1343         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1344 }
1345
1346 static int verify_uptodate_sparse(const struct cache_entry *ce,
1347                                   struct unpack_trees_options *o)
1348 {
1349         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1350 }
1351
1352 static void invalidate_ce_path(const struct cache_entry *ce,
1353                                struct unpack_trees_options *o)
1354 {
1355         if (!ce)
1356                 return;
1357         cache_tree_invalidate_path(o->src_index, ce->name);
1358         untracked_cache_invalidate_path(o->src_index, ce->name);
1359 }
1360
1361 /*
1362  * Check that checking out ce->sha1 in subdir ce->name is not
1363  * going to overwrite any working files.
1364  *
1365  * Currently, git does not checkout subprojects during a superproject
1366  * checkout, so it is not going to overwrite anything.
1367  */
1368 static int verify_clean_submodule(const struct cache_entry *ce,
1369                                   enum unpack_trees_error_types error_type,
1370                                   struct unpack_trees_options *o)
1371 {
1372         return 0;
1373 }
1374
1375 static int verify_clean_subdirectory(const struct cache_entry *ce,
1376                                      enum unpack_trees_error_types error_type,
1377                                      struct unpack_trees_options *o)
1378 {
1379         /*
1380          * we are about to extract "ce->name"; we would not want to lose
1381          * anything in the existing directory there.
1382          */
1383         int namelen;
1384         int i;
1385         struct dir_struct d;
1386         char *pathbuf;
1387         int cnt = 0;
1388         unsigned char sha1[20];
1389
1390         if (S_ISGITLINK(ce->ce_mode) &&
1391             resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
1392                 /* If we are not going to update the submodule, then
1393                  * we don't care.
1394                  */
1395                 if (!hashcmp(sha1, ce->oid.hash))
1396                         return 0;
1397                 return verify_clean_submodule(ce, error_type, o);
1398         }
1399
1400         /*
1401          * First let's make sure we do not have a local modification
1402          * in that directory.
1403          */
1404         namelen = ce_namelen(ce);
1405         for (i = locate_in_src_index(ce, o);
1406              i < o->src_index->cache_nr;
1407              i++) {
1408                 struct cache_entry *ce2 = o->src_index->cache[i];
1409                 int len = ce_namelen(ce2);
1410                 if (len < namelen ||
1411                     strncmp(ce->name, ce2->name, namelen) ||
1412                     ce2->name[namelen] != '/')
1413                         break;
1414                 /*
1415                  * ce2->name is an entry in the subdirectory to be
1416                  * removed.
1417                  */
1418                 if (!ce_stage(ce2)) {
1419                         if (verify_uptodate(ce2, o))
1420                                 return -1;
1421                         add_entry(o, ce2, CE_REMOVE, 0);
1422                         mark_ce_used(ce2, o);
1423                 }
1424                 cnt++;
1425         }
1426
1427         /*
1428          * Then we need to make sure that we do not lose a locally
1429          * present file that is not ignored.
1430          */
1431         pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1432
1433         memset(&d, 0, sizeof(d));
1434         if (o->dir)
1435                 d.exclude_per_dir = o->dir->exclude_per_dir;
1436         i = read_directory(&d, pathbuf, namelen+1, NULL);
1437         if (i)
1438                 return o->gently ? -1 :
1439                         add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1440         free(pathbuf);
1441         return cnt;
1442 }
1443
1444 /*
1445  * This gets called when there was no index entry for the tree entry 'dst',
1446  * but we found a file in the working tree that 'lstat()' said was fine,
1447  * and we're on a case-insensitive filesystem.
1448  *
1449  * See if we can find a case-insensitive match in the index that also
1450  * matches the stat information, and assume it's that other file!
1451  */
1452 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1453 {
1454         const struct cache_entry *src;
1455
1456         src = index_file_exists(o->src_index, name, len, 1);
1457         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1458 }
1459
1460 static int check_ok_to_remove(const char *name, int len, int dtype,
1461                               const struct cache_entry *ce, struct stat *st,
1462                               enum unpack_trees_error_types error_type,
1463                               struct unpack_trees_options *o)
1464 {
1465         const struct cache_entry *result;
1466
1467         /*
1468          * It may be that the 'lstat()' succeeded even though
1469          * target 'ce' was absent, because there is an old
1470          * entry that is different only in case..
1471          *
1472          * Ignore that lstat() if it matches.
1473          */
1474         if (ignore_case && icase_exists(o, name, len, st))
1475                 return 0;
1476
1477         if (o->dir &&
1478             is_excluded(o->dir, name, &dtype))
1479                 /*
1480                  * ce->name is explicitly excluded, so it is Ok to
1481                  * overwrite it.
1482                  */
1483                 return 0;
1484         if (S_ISDIR(st->st_mode)) {
1485                 /*
1486                  * We are checking out path "foo" and
1487                  * found "foo/." in the working tree.
1488                  * This is tricky -- if we have modified
1489                  * files that are in "foo/" we would lose
1490                  * them.
1491                  */
1492                 if (verify_clean_subdirectory(ce, error_type, o) < 0)
1493                         return -1;
1494                 return 0;
1495         }
1496
1497         /*
1498          * The previous round may already have decided to
1499          * delete this path, which is in a subdirectory that
1500          * is being replaced with a blob.
1501          */
1502         result = index_file_exists(&o->result, name, len, 0);
1503         if (result) {
1504                 if (result->ce_flags & CE_REMOVE)
1505                         return 0;
1506         }
1507
1508         return o->gently ? -1 :
1509                 add_rejected_path(o, error_type, name);
1510 }
1511
1512 /*
1513  * We do not want to remove or overwrite a working tree file that
1514  * is not tracked, unless it is ignored.
1515  */
1516 static int verify_absent_1(const struct cache_entry *ce,
1517                            enum unpack_trees_error_types error_type,
1518                            struct unpack_trees_options *o)
1519 {
1520         int len;
1521         struct stat st;
1522
1523         if (o->index_only || o->reset || !o->update)
1524                 return 0;
1525
1526         len = check_leading_path(ce->name, ce_namelen(ce));
1527         if (!len)
1528                 return 0;
1529         else if (len > 0) {
1530                 char *path;
1531                 int ret;
1532
1533                 path = xmemdupz(ce->name, len);
1534                 if (lstat(path, &st))
1535                         ret = error_errno("cannot stat '%s'", path);
1536                 else
1537                         ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
1538                                                  &st, error_type, o);
1539                 free(path);
1540                 return ret;
1541         } else if (lstat(ce->name, &st)) {
1542                 if (errno != ENOENT)
1543                         return error_errno("cannot stat '%s'", ce->name);
1544                 return 0;
1545         } else {
1546                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1547                                           ce_to_dtype(ce), ce, &st,
1548                                           error_type, o);
1549         }
1550 }
1551
1552 static int verify_absent(const struct cache_entry *ce,
1553                          enum unpack_trees_error_types error_type,
1554                          struct unpack_trees_options *o)
1555 {
1556         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1557                 return 0;
1558         return verify_absent_1(ce, error_type, o);
1559 }
1560
1561 static int verify_absent_sparse(const struct cache_entry *ce,
1562                                 enum unpack_trees_error_types error_type,
1563                                 struct unpack_trees_options *o)
1564 {
1565         enum unpack_trees_error_types orphaned_error = error_type;
1566         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1567                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1568
1569         return verify_absent_1(ce, orphaned_error, o);
1570 }
1571
1572 static int merged_entry(const struct cache_entry *ce,
1573                         const struct cache_entry *old,
1574                         struct unpack_trees_options *o)
1575 {
1576         int update = CE_UPDATE;
1577         struct cache_entry *merge = dup_entry(ce);
1578
1579         if (!old) {
1580                 /*
1581                  * New index entries. In sparse checkout, the following
1582                  * verify_absent() will be delayed until after
1583                  * traverse_trees() finishes in unpack_trees(), then:
1584                  *
1585                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1586                  *  - verify_absent() be called again, this time with
1587                  *    correct CE_NEW_SKIP_WORKTREE
1588                  *
1589                  * verify_absent() call here does nothing in sparse
1590                  * checkout (i.e. o->skip_sparse_checkout == 0)
1591                  */
1592                 update |= CE_ADDED;
1593                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1594
1595                 if (verify_absent(merge,
1596                                   ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1597                         free(merge);
1598                         return -1;
1599                 }
1600                 invalidate_ce_path(merge, o);
1601         } else if (!(old->ce_flags & CE_CONFLICTED)) {
1602                 /*
1603                  * See if we can re-use the old CE directly?
1604                  * That way we get the uptodate stat info.
1605                  *
1606                  * This also removes the UPDATE flag on a match; otherwise
1607                  * we will end up overwriting local changes in the work tree.
1608                  */
1609                 if (same(old, merge)) {
1610                         copy_cache_entry(merge, old);
1611                         update = 0;
1612                 } else {
1613                         if (verify_uptodate(old, o)) {
1614                                 free(merge);
1615                                 return -1;
1616                         }
1617                         /* Migrate old flags over */
1618                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1619                         invalidate_ce_path(old, o);
1620                 }
1621         } else {
1622                 /*
1623                  * Previously unmerged entry left as an existence
1624                  * marker by read_index_unmerged();
1625                  */
1626                 invalidate_ce_path(old, o);
1627         }
1628
1629         do_add_entry(o, merge, update, CE_STAGEMASK);
1630         return 1;
1631 }
1632
1633 static int deleted_entry(const struct cache_entry *ce,
1634                          const struct cache_entry *old,
1635                          struct unpack_trees_options *o)
1636 {
1637         /* Did it exist in the index? */
1638         if (!old) {
1639                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1640                         return -1;
1641                 return 0;
1642         }
1643         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1644                 return -1;
1645         add_entry(o, ce, CE_REMOVE, 0);
1646         invalidate_ce_path(ce, o);
1647         return 1;
1648 }
1649
1650 static int keep_entry(const struct cache_entry *ce,
1651                       struct unpack_trees_options *o)
1652 {
1653         add_entry(o, ce, 0, 0);
1654         return 1;
1655 }
1656
1657 #if DBRT_DEBUG
1658 static void show_stage_entry(FILE *o,
1659                              const char *label, const struct cache_entry *ce)
1660 {
1661         if (!ce)
1662                 fprintf(o, "%s (missing)\n", label);
1663         else
1664                 fprintf(o, "%s%06o %s %d\t%s\n",
1665                         label,
1666                         ce->ce_mode,
1667                         oid_to_hex(&ce->oid),
1668                         ce_stage(ce),
1669                         ce->name);
1670 }
1671 #endif
1672
1673 int threeway_merge(const struct cache_entry * const *stages,
1674                    struct unpack_trees_options *o)
1675 {
1676         const struct cache_entry *index;
1677         const struct cache_entry *head;
1678         const struct cache_entry *remote = stages[o->head_idx + 1];
1679         int count;
1680         int head_match = 0;
1681         int remote_match = 0;
1682
1683         int df_conflict_head = 0;
1684         int df_conflict_remote = 0;
1685
1686         int any_anc_missing = 0;
1687         int no_anc_exists = 1;
1688         int i;
1689
1690         for (i = 1; i < o->head_idx; i++) {
1691                 if (!stages[i] || stages[i] == o->df_conflict_entry)
1692                         any_anc_missing = 1;
1693                 else
1694                         no_anc_exists = 0;
1695         }
1696
1697         index = stages[0];
1698         head = stages[o->head_idx];
1699
1700         if (head == o->df_conflict_entry) {
1701                 df_conflict_head = 1;
1702                 head = NULL;
1703         }
1704
1705         if (remote == o->df_conflict_entry) {
1706                 df_conflict_remote = 1;
1707                 remote = NULL;
1708         }
1709
1710         /*
1711          * First, if there's a #16 situation, note that to prevent #13
1712          * and #14.
1713          */
1714         if (!same(remote, head)) {
1715                 for (i = 1; i < o->head_idx; i++) {
1716                         if (same(stages[i], head)) {
1717                                 head_match = i;
1718                         }
1719                         if (same(stages[i], remote)) {
1720                                 remote_match = i;
1721                         }
1722                 }
1723         }
1724
1725         /*
1726          * We start with cases where the index is allowed to match
1727          * something other than the head: #14(ALT) and #2ALT, where it
1728          * is permitted to match the result instead.
1729          */
1730         /* #14, #14ALT, #2ALT */
1731         if (remote && !df_conflict_head && head_match && !remote_match) {
1732                 if (index && !same(index, remote) && !same(index, head))
1733                         return reject_merge(index, o);
1734                 return merged_entry(remote, index, o);
1735         }
1736         /*
1737          * If we have an entry in the index cache, then we want to
1738          * make sure that it matches head.
1739          */
1740         if (index && !same(index, head))
1741                 return reject_merge(index, o);
1742
1743         if (head) {
1744                 /* #5ALT, #15 */
1745                 if (same(head, remote))
1746                         return merged_entry(head, index, o);
1747                 /* #13, #3ALT */
1748                 if (!df_conflict_remote && remote_match && !head_match)
1749                         return merged_entry(head, index, o);
1750         }
1751
1752         /* #1 */
1753         if (!head && !remote && any_anc_missing)
1754                 return 0;
1755
1756         /*
1757          * Under the "aggressive" rule, we resolve mostly trivial
1758          * cases that we historically had git-merge-one-file resolve.
1759          */
1760         if (o->aggressive) {
1761                 int head_deleted = !head;
1762                 int remote_deleted = !remote;
1763                 const struct cache_entry *ce = NULL;
1764
1765                 if (index)
1766                         ce = index;
1767                 else if (head)
1768                         ce = head;
1769                 else if (remote)
1770                         ce = remote;
1771                 else {
1772                         for (i = 1; i < o->head_idx; i++) {
1773                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
1774                                         ce = stages[i];
1775                                         break;
1776                                 }
1777                         }
1778                 }
1779
1780                 /*
1781                  * Deleted in both.
1782                  * Deleted in one and unchanged in the other.
1783                  */
1784                 if ((head_deleted && remote_deleted) ||
1785                     (head_deleted && remote && remote_match) ||
1786                     (remote_deleted && head && head_match)) {
1787                         if (index)
1788                                 return deleted_entry(index, index, o);
1789                         if (ce && !head_deleted) {
1790                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1791                                         return -1;
1792                         }
1793                         return 0;
1794                 }
1795                 /*
1796                  * Added in both, identically.
1797                  */
1798                 if (no_anc_exists && head && remote && same(head, remote))
1799                         return merged_entry(head, index, o);
1800
1801         }
1802
1803         /* Below are "no merge" cases, which require that the index be
1804          * up-to-date to avoid the files getting overwritten with
1805          * conflict resolution files.
1806          */
1807         if (index) {
1808                 if (verify_uptodate(index, o))
1809                         return -1;
1810         }
1811
1812         o->nontrivial_merge = 1;
1813
1814         /* #2, #3, #4, #6, #7, #9, #10, #11. */
1815         count = 0;
1816         if (!head_match || !remote_match) {
1817                 for (i = 1; i < o->head_idx; i++) {
1818                         if (stages[i] && stages[i] != o->df_conflict_entry) {
1819                                 keep_entry(stages[i], o);
1820                                 count++;
1821                                 break;
1822                         }
1823                 }
1824         }
1825 #if DBRT_DEBUG
1826         else {
1827                 fprintf(stderr, "read-tree: warning #16 detected\n");
1828                 show_stage_entry(stderr, "head   ", stages[head_match]);
1829                 show_stage_entry(stderr, "remote ", stages[remote_match]);
1830         }
1831 #endif
1832         if (head) { count += keep_entry(head, o); }
1833         if (remote) { count += keep_entry(remote, o); }
1834         return count;
1835 }
1836
1837 /*
1838  * Two-way merge.
1839  *
1840  * The rule is to "carry forward" what is in the index without losing
1841  * information across a "fast-forward", favoring a successful merge
1842  * over a merge failure when it makes sense.  For details of the
1843  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
1844  *
1845  */
1846 int twoway_merge(const struct cache_entry * const *src,
1847                  struct unpack_trees_options *o)
1848 {
1849         const struct cache_entry *current = src[0];
1850         const struct cache_entry *oldtree = src[1];
1851         const struct cache_entry *newtree = src[2];
1852
1853         if (o->merge_size != 2)
1854                 return error("Cannot do a twoway merge of %d trees",
1855                              o->merge_size);
1856
1857         if (oldtree == o->df_conflict_entry)
1858                 oldtree = NULL;
1859         if (newtree == o->df_conflict_entry)
1860                 newtree = NULL;
1861
1862         if (current) {
1863                 if (current->ce_flags & CE_CONFLICTED) {
1864                         if (same(oldtree, newtree) || o->reset) {
1865                                 if (!newtree)
1866                                         return deleted_entry(current, current, o);
1867                                 else
1868                                         return merged_entry(newtree, current, o);
1869                         }
1870                         return reject_merge(current, o);
1871                 } else if ((!oldtree && !newtree) || /* 4 and 5 */
1872                          (!oldtree && newtree &&
1873                           same(current, newtree)) || /* 6 and 7 */
1874                          (oldtree && newtree &&
1875                           same(oldtree, newtree)) || /* 14 and 15 */
1876                          (oldtree && newtree &&
1877                           !same(oldtree, newtree) && /* 18 and 19 */
1878                           same(current, newtree))) {
1879                         return keep_entry(current, o);
1880                 } else if (oldtree && !newtree && same(current, oldtree)) {
1881                         /* 10 or 11 */
1882                         return deleted_entry(oldtree, current, o);
1883                 } else if (oldtree && newtree &&
1884                          same(current, oldtree) && !same(current, newtree)) {
1885                         /* 20 or 21 */
1886                         return merged_entry(newtree, current, o);
1887                 } else
1888                         return reject_merge(current, o);
1889         }
1890         else if (newtree) {
1891                 if (oldtree && !o->initial_checkout) {
1892                         /*
1893                          * deletion of the path was staged;
1894                          */
1895                         if (same(oldtree, newtree))
1896                                 return 1;
1897                         return reject_merge(oldtree, o);
1898                 }
1899                 return merged_entry(newtree, current, o);
1900         }
1901         return deleted_entry(oldtree, current, o);
1902 }
1903
1904 /*
1905  * Bind merge.
1906  *
1907  * Keep the index entries at stage0, collapse stage1 but make sure
1908  * stage0 does not have anything there.
1909  */
1910 int bind_merge(const struct cache_entry * const *src,
1911                struct unpack_trees_options *o)
1912 {
1913         const struct cache_entry *old = src[0];
1914         const struct cache_entry *a = src[1];
1915
1916         if (o->merge_size != 1)
1917                 return error("Cannot do a bind merge of %d trees",
1918                              o->merge_size);
1919         if (a && old)
1920                 return o->gently ? -1 :
1921                         error(ERRORMSG(o, ERROR_BIND_OVERLAP), a->name, old->name);
1922         if (!a)
1923                 return keep_entry(old, o);
1924         else
1925                 return merged_entry(a, NULL, o);
1926 }
1927
1928 /*
1929  * One-way merge.
1930  *
1931  * The rule is:
1932  * - take the stat information from stage0, take the data from stage1
1933  */
1934 int oneway_merge(const struct cache_entry * const *src,
1935                  struct unpack_trees_options *o)
1936 {
1937         const struct cache_entry *old = src[0];
1938         const struct cache_entry *a = src[1];
1939
1940         if (o->merge_size != 1)
1941                 return error("Cannot do a oneway merge of %d trees",
1942                              o->merge_size);
1943
1944         if (!a || a == o->df_conflict_entry)
1945                 return deleted_entry(old, old, o);
1946
1947         if (old && same(old, a)) {
1948                 int update = 0;
1949                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
1950                         struct stat st;
1951                         if (lstat(old->name, &st) ||
1952                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
1953                                 update |= CE_UPDATE;
1954                 }
1955                 add_entry(o, old, update, 0);
1956                 return 0;
1957         }
1958         return merged_entry(a, old, o);
1959 }