Merge branch 'master' of git://ozlabs.org/~paulus/gitk
[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
13 /*
14  * Error messages expected by scripts out of plumbing commands such as
15  * read-tree.  Non-scripted Porcelain is not required to use these messages
16  * and in fact are encouraged to reword them to better suit their particular
17  * situation better.  See how "git checkout" and "git merge" replaces
18  * them using setup_unpack_trees_porcelain(), for example.
19  */
20 static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
21         /* ERROR_WOULD_OVERWRITE */
22         "Entry '%s' would be overwritten by merge. Cannot merge.",
23
24         /* ERROR_NOT_UPTODATE_FILE */
25         "Entry '%s' not uptodate. Cannot merge.",
26
27         /* ERROR_NOT_UPTODATE_DIR */
28         "Updating '%s' would lose untracked files in it",
29
30         /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
31         "Untracked working tree file '%s' would be overwritten by merge.",
32
33         /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
34         "Untracked working tree file '%s' would be removed by merge.",
35
36         /* ERROR_BIND_OVERLAP */
37         "Entry '%s' overlaps with '%s'.  Cannot bind.",
38
39         /* ERROR_SPARSE_NOT_UPTODATE_FILE */
40         "Entry '%s' not uptodate. Cannot update sparse checkout.",
41
42         /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
43         "Working tree file '%s' would be overwritten by sparse checkout update.",
44
45         /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
46         "Working tree file '%s' would be removed by sparse checkout update.",
47 };
48
49 #define ERRORMSG(o,type) \
50         ( ((o) && (o)->msgs[(type)]) \
51           ? ((o)->msgs[(type)])      \
52           : (unpack_plumbing_errors[(type)]) )
53
54 void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
55                                   const char *cmd)
56 {
57         int i;
58         const char **msgs = opts->msgs;
59         const char *msg;
60         const char *cmd2 = strcmp(cmd, "checkout") ? cmd : "switch branches";
61
62         if (advice_commit_before_merge)
63                 msg = "Your local changes to the following files would be overwritten by %s:\n%%s"
64                         "Please, commit your changes or stash them before you can %s.";
65         else
66                 msg = "Your local changes to the following files would be overwritten by %s:\n%%s";
67         msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
68                 xstrfmt(msg, cmd, cmd2);
69
70         msgs[ERROR_NOT_UPTODATE_DIR] =
71                 "Updating the following directories would lose untracked files in it:\n%s";
72
73         if (advice_commit_before_merge)
74                 msg = "The following untracked working tree files would be %s by %s:\n%%s"
75                         "Please move or remove them before you can %s.";
76         else
77                 msg = "The following untracked working tree files would be %s by %s:\n%%s";
78
79         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = xstrfmt(msg, "removed", cmd, cmd2);
80         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = xstrfmt(msg, "overwritten", cmd, cmd2);
81
82         /*
83          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
84          * cannot easily display it as a list.
85          */
86         msgs[ERROR_BIND_OVERLAP] = "Entry '%s' overlaps with '%s'.  Cannot bind.";
87
88         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
89                 "Cannot update sparse checkout: the following entries are not up-to-date:\n%s";
90         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
91                 "The following Working tree files would be overwritten by sparse checkout update:\n%s";
92         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
93                 "The following Working tree files would be removed by sparse checkout update:\n%s";
94
95         opts->show_all_errors = 1;
96         /* rejected paths may not have a static buffer */
97         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
98                 opts->unpack_rejects[i].strdup_strings = 1;
99 }
100
101 static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
102                          unsigned int set, unsigned int clear)
103 {
104         clear |= CE_HASHED;
105
106         if (set & CE_REMOVE)
107                 set |= CE_WT_REMOVE;
108
109         ce->ce_flags = (ce->ce_flags & ~clear) | set;
110         return add_index_entry(&o->result, ce,
111                                ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
112 }
113
114 static struct cache_entry *dup_entry(const struct cache_entry *ce)
115 {
116         unsigned int size = ce_size(ce);
117         struct cache_entry *new = xmalloc(size);
118
119         memcpy(new, ce, size);
120         return new;
121 }
122
123 static void add_entry(struct unpack_trees_options *o,
124                       const struct cache_entry *ce,
125                       unsigned int set, unsigned int clear)
126 {
127         do_add_entry(o, dup_entry(ce), set, clear);
128 }
129
130 /*
131  * add error messages on path <path>
132  * corresponding to the type <e> with the message <msg>
133  * indicating if it should be display in porcelain or not
134  */
135 static int add_rejected_path(struct unpack_trees_options *o,
136                              enum unpack_trees_error_types e,
137                              const char *path)
138 {
139         if (!o->show_all_errors)
140                 return error(ERRORMSG(o, e), path);
141
142         /*
143          * Otherwise, insert in a list for future display by
144          * display_error_msgs()
145          */
146         string_list_append(&o->unpack_rejects[e], path);
147         return -1;
148 }
149
150 /*
151  * display all the error messages stored in a nice way
152  */
153 static void display_error_msgs(struct unpack_trees_options *o)
154 {
155         int e, i;
156         int something_displayed = 0;
157         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
158                 struct string_list *rejects = &o->unpack_rejects[e];
159                 if (rejects->nr > 0) {
160                         struct strbuf path = STRBUF_INIT;
161                         something_displayed = 1;
162                         for (i = 0; i < rejects->nr; i++)
163                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
164                         error(ERRORMSG(o, e), path.buf);
165                         strbuf_release(&path);
166                 }
167                 string_list_clear(rejects, 0);
168         }
169         if (something_displayed)
170                 fprintf(stderr, "Aborting\n");
171 }
172
173 /*
174  * Unlink the last component and schedule the leading directories for
175  * removal, such that empty directories get removed.
176  */
177 static void unlink_entry(const struct cache_entry *ce)
178 {
179         if (!check_leading_path(ce->name, ce_namelen(ce)))
180                 return;
181         if (remove_or_warn(ce->ce_mode, ce->name))
182                 return;
183         schedule_dir_for_removal(ce->name, ce_namelen(ce));
184 }
185
186 static struct checkout state;
187 static int check_updates(struct unpack_trees_options *o)
188 {
189         unsigned cnt = 0, total = 0;
190         struct progress *progress = NULL;
191         struct index_state *index = &o->result;
192         int i;
193         int errs = 0;
194
195         if (o->update && o->verbose_update) {
196                 for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
197                         const struct cache_entry *ce = index->cache[cnt];
198                         if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
199                                 total++;
200                 }
201
202                 progress = start_progress_delay(_("Checking out files"),
203                                                 total, 50, 1);
204                 cnt = 0;
205         }
206
207         if (o->update)
208                 git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
209         for (i = 0; i < index->cache_nr; i++) {
210                 const struct cache_entry *ce = index->cache[i];
211
212                 if (ce->ce_flags & CE_WT_REMOVE) {
213                         display_progress(progress, ++cnt);
214                         if (o->update && !o->dry_run)
215                                 unlink_entry(ce);
216                         continue;
217                 }
218         }
219         remove_marked_cache_entries(&o->result);
220         remove_scheduled_dirs();
221
222         for (i = 0; i < index->cache_nr; i++) {
223                 struct cache_entry *ce = index->cache[i];
224
225                 if (ce->ce_flags & CE_UPDATE) {
226                         display_progress(progress, ++cnt);
227                         ce->ce_flags &= ~CE_UPDATE;
228                         if (o->update && !o->dry_run) {
229                                 errs |= checkout_entry(ce, &state, NULL);
230                         }
231                 }
232         }
233         stop_progress(&progress);
234         if (o->update)
235                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
236         return errs != 0;
237 }
238
239 static int verify_uptodate_sparse(const struct cache_entry *ce,
240                                   struct unpack_trees_options *o);
241 static int verify_absent_sparse(const struct cache_entry *ce,
242                                 enum unpack_trees_error_types,
243                                 struct unpack_trees_options *o);
244
245 static int apply_sparse_checkout(struct index_state *istate,
246                                  struct cache_entry *ce,
247                                  struct unpack_trees_options *o)
248 {
249         int was_skip_worktree = ce_skip_worktree(ce);
250
251         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
252                 ce->ce_flags |= CE_SKIP_WORKTREE;
253         else
254                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
255         if (was_skip_worktree != ce_skip_worktree(ce)) {
256                 ce->ce_flags |= CE_UPDATE_IN_BASE;
257                 istate->cache_changed |= CE_ENTRY_CHANGED;
258         }
259
260         /*
261          * if (!was_skip_worktree && !ce_skip_worktree()) {
262          *      This is perfectly normal. Move on;
263          * }
264          */
265
266         /*
267          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
268          * area as a result of ce_skip_worktree() shortcuts in
269          * verify_absent() and verify_uptodate().
270          * Make sure they don't modify worktree if they are already
271          * outside checkout area
272          */
273         if (was_skip_worktree && ce_skip_worktree(ce)) {
274                 ce->ce_flags &= ~CE_UPDATE;
275
276                 /*
277                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
278                  * on to get that file removed from both index and worktree.
279                  * If that file is already outside worktree area, don't
280                  * bother remove it.
281                  */
282                 if (ce->ce_flags & CE_REMOVE)
283                         ce->ce_flags &= ~CE_WT_REMOVE;
284         }
285
286         if (!was_skip_worktree && ce_skip_worktree(ce)) {
287                 /*
288                  * If CE_UPDATE is set, verify_uptodate() must be called already
289                  * also stat info may have lost after merged_entry() so calling
290                  * verify_uptodate() again may fail
291                  */
292                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
293                         return -1;
294                 ce->ce_flags |= CE_WT_REMOVE;
295         }
296         if (was_skip_worktree && !ce_skip_worktree(ce)) {
297                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
298                         return -1;
299                 ce->ce_flags |= CE_UPDATE;
300         }
301         return 0;
302 }
303
304 static inline int call_unpack_fn(const struct cache_entry * const *src,
305                                  struct unpack_trees_options *o)
306 {
307         int ret = o->fn(src, o);
308         if (ret > 0)
309                 ret = 0;
310         return ret;
311 }
312
313 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
314 {
315         ce->ce_flags |= CE_UNPACKED;
316
317         if (o->cache_bottom < o->src_index->cache_nr &&
318             o->src_index->cache[o->cache_bottom] == ce) {
319                 int bottom = o->cache_bottom;
320                 while (bottom < o->src_index->cache_nr &&
321                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
322                         bottom++;
323                 o->cache_bottom = bottom;
324         }
325 }
326
327 static void mark_all_ce_unused(struct index_state *index)
328 {
329         int i;
330         for (i = 0; i < index->cache_nr; i++)
331                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
332 }
333
334 static int locate_in_src_index(const struct cache_entry *ce,
335                                struct unpack_trees_options *o)
336 {
337         struct index_state *index = o->src_index;
338         int len = ce_namelen(ce);
339         int pos = index_name_pos(index, ce->name, len);
340         if (pos < 0)
341                 pos = -1 - pos;
342         return pos;
343 }
344
345 /*
346  * We call unpack_index_entry() with an unmerged cache entry
347  * only in diff-index, and it wants a single callback.  Skip
348  * the other unmerged entry with the same name.
349  */
350 static void mark_ce_used_same_name(struct cache_entry *ce,
351                                    struct unpack_trees_options *o)
352 {
353         struct index_state *index = o->src_index;
354         int len = ce_namelen(ce);
355         int pos;
356
357         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
358                 struct cache_entry *next = index->cache[pos];
359                 if (len != ce_namelen(next) ||
360                     memcmp(ce->name, next->name, len))
361                         break;
362                 mark_ce_used(next, o);
363         }
364 }
365
366 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
367 {
368         const struct index_state *index = o->src_index;
369         int pos = o->cache_bottom;
370
371         while (pos < index->cache_nr) {
372                 struct cache_entry *ce = index->cache[pos];
373                 if (!(ce->ce_flags & CE_UNPACKED))
374                         return ce;
375                 pos++;
376         }
377         return NULL;
378 }
379
380 static void add_same_unmerged(const struct cache_entry *ce,
381                               struct unpack_trees_options *o)
382 {
383         struct index_state *index = o->src_index;
384         int len = ce_namelen(ce);
385         int pos = index_name_pos(index, ce->name, len);
386
387         if (0 <= pos)
388                 die("programming error in a caller of mark_ce_used_same_name");
389         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
390                 struct cache_entry *next = index->cache[pos];
391                 if (len != ce_namelen(next) ||
392                     memcmp(ce->name, next->name, len))
393                         break;
394                 add_entry(o, next, 0, 0);
395                 mark_ce_used(next, o);
396         }
397 }
398
399 static int unpack_index_entry(struct cache_entry *ce,
400                               struct unpack_trees_options *o)
401 {
402         const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
403         int ret;
404
405         src[0] = ce;
406
407         mark_ce_used(ce, o);
408         if (ce_stage(ce)) {
409                 if (o->skip_unmerged) {
410                         add_entry(o, ce, 0, 0);
411                         return 0;
412                 }
413         }
414         ret = call_unpack_fn(src, o);
415         if (ce_stage(ce))
416                 mark_ce_used_same_name(ce, o);
417         return ret;
418 }
419
420 static int find_cache_pos(struct traverse_info *, const struct name_entry *);
421
422 static void restore_cache_bottom(struct traverse_info *info, int bottom)
423 {
424         struct unpack_trees_options *o = info->data;
425
426         if (o->diff_index_cached)
427                 return;
428         o->cache_bottom = bottom;
429 }
430
431 static int switch_cache_bottom(struct traverse_info *info)
432 {
433         struct unpack_trees_options *o = info->data;
434         int ret, pos;
435
436         if (o->diff_index_cached)
437                 return 0;
438         ret = o->cache_bottom;
439         pos = find_cache_pos(info->prev, &info->name);
440
441         if (pos < -1)
442                 o->cache_bottom = -2 - pos;
443         else if (pos < 0)
444                 o->cache_bottom = o->src_index->cache_nr;
445         return ret;
446 }
447
448 static int traverse_trees_recursive(int n, unsigned long dirmask,
449                                     unsigned long df_conflicts,
450                                     struct name_entry *names,
451                                     struct traverse_info *info)
452 {
453         int i, ret, bottom;
454         struct tree_desc t[MAX_UNPACK_TREES];
455         void *buf[MAX_UNPACK_TREES];
456         struct traverse_info newinfo;
457         struct name_entry *p;
458
459         p = names;
460         while (!p->mode)
461                 p++;
462
463         newinfo = *info;
464         newinfo.prev = info;
465         newinfo.pathspec = info->pathspec;
466         newinfo.name = *p;
467         newinfo.pathlen += tree_entry_len(p) + 1;
468         newinfo.df_conflicts |= df_conflicts;
469
470         for (i = 0; i < n; i++, dirmask >>= 1) {
471                 const unsigned char *sha1 = NULL;
472                 if (dirmask & 1)
473                         sha1 = names[i].sha1;
474                 buf[i] = fill_tree_descriptor(t+i, sha1);
475         }
476
477         bottom = switch_cache_bottom(&newinfo);
478         ret = traverse_trees(n, t, &newinfo);
479         restore_cache_bottom(&newinfo, bottom);
480
481         for (i = 0; i < n; i++)
482                 free(buf[i]);
483
484         return ret;
485 }
486
487 /*
488  * Compare the traverse-path to the cache entry without actually
489  * having to generate the textual representation of the traverse
490  * path.
491  *
492  * NOTE! This *only* compares up to the size of the traverse path
493  * itself - the caller needs to do the final check for the cache
494  * entry having more data at the end!
495  */
496 static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
497 {
498         int len, pathlen, ce_len;
499         const char *ce_name;
500
501         if (info->prev) {
502                 int cmp = do_compare_entry(ce, info->prev, &info->name);
503                 if (cmp)
504                         return cmp;
505         }
506         pathlen = info->pathlen;
507         ce_len = ce_namelen(ce);
508
509         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
510         if (ce_len < pathlen)
511                 return -1;
512
513         ce_len -= pathlen;
514         ce_name = ce->name + pathlen;
515
516         len = tree_entry_len(n);
517         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
518 }
519
520 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
521 {
522         int cmp = do_compare_entry(ce, info, n);
523         if (cmp)
524                 return cmp;
525
526         /*
527          * Even if the beginning compared identically, the ce should
528          * compare as bigger than a directory leading up to it!
529          */
530         return ce_namelen(ce) > traverse_path_len(info, n);
531 }
532
533 static int ce_in_traverse_path(const struct cache_entry *ce,
534                                const struct traverse_info *info)
535 {
536         if (!info->prev)
537                 return 1;
538         if (do_compare_entry(ce, info->prev, &info->name))
539                 return 0;
540         /*
541          * If ce (blob) is the same name as the path (which is a tree
542          * we will be descending into), it won't be inside it.
543          */
544         return (info->pathlen < ce_namelen(ce));
545 }
546
547 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
548 {
549         int len = traverse_path_len(info, n);
550         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
551
552         ce->ce_mode = create_ce_mode(n->mode);
553         ce->ce_flags = create_ce_flags(stage);
554         ce->ce_namelen = len;
555         hashcpy(ce->sha1, n->sha1);
556         make_traverse_path(ce->name, info, n);
557
558         return ce;
559 }
560
561 static int unpack_nondirectories(int n, unsigned long mask,
562                                  unsigned long dirmask,
563                                  struct cache_entry **src,
564                                  const struct name_entry *names,
565                                  const struct traverse_info *info)
566 {
567         int i;
568         struct unpack_trees_options *o = info->data;
569         unsigned long conflicts = info->df_conflicts | dirmask;
570
571         /* Do we have *only* directories? Nothing to do */
572         if (mask == dirmask && !src[0])
573                 return 0;
574
575         /*
576          * Ok, we've filled in up to any potential index entry in src[0],
577          * now do the rest.
578          */
579         for (i = 0; i < n; i++) {
580                 int stage;
581                 unsigned int bit = 1ul << i;
582                 if (conflicts & bit) {
583                         src[i + o->merge] = o->df_conflict_entry;
584                         continue;
585                 }
586                 if (!(mask & bit))
587                         continue;
588                 if (!o->merge)
589                         stage = 0;
590                 else if (i + 1 < o->head_idx)
591                         stage = 1;
592                 else if (i + 1 > o->head_idx)
593                         stage = 3;
594                 else
595                         stage = 2;
596                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
597         }
598
599         if (o->merge) {
600                 int rc = call_unpack_fn((const struct cache_entry * const *)src,
601                                         o);
602                 for (i = 0; i < n; i++) {
603                         struct cache_entry *ce = src[i + o->merge];
604                         if (ce != o->df_conflict_entry)
605                                 free(ce);
606                 }
607                 return rc;
608         }
609
610         for (i = 0; i < n; i++)
611                 if (src[i] && src[i] != o->df_conflict_entry)
612                         if (do_add_entry(o, src[i], 0, 0))
613                                 return -1;
614
615         return 0;
616 }
617
618 static int unpack_failed(struct unpack_trees_options *o, const char *message)
619 {
620         discard_index(&o->result);
621         if (!o->gently && !o->exiting_early) {
622                 if (message)
623                         return error("%s", message);
624                 return -1;
625         }
626         return -1;
627 }
628
629 /*
630  * The tree traversal is looking at name p.  If we have a matching entry,
631  * return it.  If name p is a directory in the index, do not return
632  * anything, as we will want to match it when the traversal descends into
633  * the directory.
634  */
635 static int find_cache_pos(struct traverse_info *info,
636                           const struct name_entry *p)
637 {
638         int pos;
639         struct unpack_trees_options *o = info->data;
640         struct index_state *index = o->src_index;
641         int pfxlen = info->pathlen;
642         int p_len = tree_entry_len(p);
643
644         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
645                 const struct cache_entry *ce = index->cache[pos];
646                 const char *ce_name, *ce_slash;
647                 int cmp, ce_len;
648
649                 if (ce->ce_flags & CE_UNPACKED) {
650                         /*
651                          * cache_bottom entry is already unpacked, so
652                          * we can never match it; don't check it
653                          * again.
654                          */
655                         if (pos == o->cache_bottom)
656                                 ++o->cache_bottom;
657                         continue;
658                 }
659                 if (!ce_in_traverse_path(ce, info))
660                         continue;
661                 ce_name = ce->name + pfxlen;
662                 ce_slash = strchr(ce_name, '/');
663                 if (ce_slash)
664                         ce_len = ce_slash - ce_name;
665                 else
666                         ce_len = ce_namelen(ce) - pfxlen;
667                 cmp = name_compare(p->path, p_len, ce_name, ce_len);
668                 /*
669                  * Exact match; if we have a directory we need to
670                  * delay returning it.
671                  */
672                 if (!cmp)
673                         return ce_slash ? -2 - pos : pos;
674                 if (0 < cmp)
675                         continue; /* keep looking */
676                 /*
677                  * ce_name sorts after p->path; could it be that we
678                  * have files under p->path directory in the index?
679                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
680                  * have "t/a" in the index.
681                  */
682                 if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
683                     ce_name[p_len] < '/')
684                         continue; /* keep looking */
685                 break;
686         }
687         return -1;
688 }
689
690 static struct cache_entry *find_cache_entry(struct traverse_info *info,
691                                             const struct name_entry *p)
692 {
693         int pos = find_cache_pos(info, p);
694         struct unpack_trees_options *o = info->data;
695
696         if (0 <= pos)
697                 return o->src_index->cache[pos];
698         else
699                 return NULL;
700 }
701
702 static void debug_path(struct traverse_info *info)
703 {
704         if (info->prev) {
705                 debug_path(info->prev);
706                 if (*info->prev->name.path)
707                         putchar('/');
708         }
709         printf("%s", info->name.path);
710 }
711
712 static void debug_name_entry(int i, struct name_entry *n)
713 {
714         printf("ent#%d %06o %s\n", i,
715                n->path ? n->mode : 0,
716                n->path ? n->path : "(missing)");
717 }
718
719 static void debug_unpack_callback(int n,
720                                   unsigned long mask,
721                                   unsigned long dirmask,
722                                   struct name_entry *names,
723                                   struct traverse_info *info)
724 {
725         int i;
726         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
727                mask, dirmask, n);
728         debug_path(info);
729         putchar('\n');
730         for (i = 0; i < n; i++)
731                 debug_name_entry(i, names + i);
732 }
733
734 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
735 {
736         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
737         struct unpack_trees_options *o = info->data;
738         const struct name_entry *p = names;
739
740         /* Find first entry with a real name (we could use "mask" too) */
741         while (!p->mode)
742                 p++;
743
744         if (o->debug_unpack)
745                 debug_unpack_callback(n, mask, dirmask, names, info);
746
747         /* Are we supposed to look at the index too? */
748         if (o->merge) {
749                 while (1) {
750                         int cmp;
751                         struct cache_entry *ce;
752
753                         if (o->diff_index_cached)
754                                 ce = next_cache_entry(o);
755                         else
756                                 ce = find_cache_entry(info, p);
757
758                         if (!ce)
759                                 break;
760                         cmp = compare_entry(ce, info, p);
761                         if (cmp < 0) {
762                                 if (unpack_index_entry(ce, o) < 0)
763                                         return unpack_failed(o, NULL);
764                                 continue;
765                         }
766                         if (!cmp) {
767                                 if (ce_stage(ce)) {
768                                         /*
769                                          * If we skip unmerged index
770                                          * entries, we'll skip this
771                                          * entry *and* the tree
772                                          * entries associated with it!
773                                          */
774                                         if (o->skip_unmerged) {
775                                                 add_same_unmerged(ce, o);
776                                                 return mask;
777                                         }
778                                 }
779                                 src[0] = ce;
780                         }
781                         break;
782                 }
783         }
784
785         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
786                 return -1;
787
788         if (o->merge && src[0]) {
789                 if (ce_stage(src[0]))
790                         mark_ce_used_same_name(src[0], o);
791                 else
792                         mark_ce_used(src[0], o);
793         }
794
795         /* Now handle any directories.. */
796         if (dirmask) {
797                 /* special case: "diff-index --cached" looking at a tree */
798                 if (o->diff_index_cached &&
799                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
800                         int matches;
801                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
802                                                                names, info);
803                         /*
804                          * Everything under the name matches; skip the
805                          * entire hierarchy.  diff_index_cached codepath
806                          * special cases D/F conflicts in such a way that
807                          * it does not do any look-ahead, so this is safe.
808                          */
809                         if (matches) {
810                                 o->cache_bottom += matches;
811                                 return mask;
812                         }
813                 }
814
815                 if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
816                                              names, info) < 0)
817                         return -1;
818                 return mask;
819         }
820
821         return mask;
822 }
823
824 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
825                             struct strbuf *prefix,
826                             int select_mask, int clear_mask,
827                             struct exclude_list *el, int defval);
828
829 /* Whole directory matching */
830 static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
831                               struct strbuf *prefix,
832                               char *basename,
833                               int select_mask, int clear_mask,
834                               struct exclude_list *el, int defval)
835 {
836         struct cache_entry **cache_end;
837         int dtype = DT_DIR;
838         int ret = is_excluded_from_list(prefix->buf, prefix->len,
839                                         basename, &dtype, el);
840         int rc;
841
842         strbuf_addch(prefix, '/');
843
844         /* If undecided, use matching result of parent dir in defval */
845         if (ret < 0)
846                 ret = defval;
847
848         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
849                 struct cache_entry *ce = *cache_end;
850                 if (strncmp(ce->name, prefix->buf, prefix->len))
851                         break;
852         }
853
854         /*
855          * TODO: check el, if there are no patterns that may conflict
856          * with ret (iow, we know in advance the incl/excl
857          * decision for the entire directory), clear flag here without
858          * calling clear_ce_flags_1(). That function will call
859          * the expensive is_excluded_from_list() on every entry.
860          */
861         rc = clear_ce_flags_1(cache, cache_end - cache,
862                               prefix,
863                               select_mask, clear_mask,
864                               el, ret);
865         strbuf_setlen(prefix, prefix->len - 1);
866         return rc;
867 }
868
869 /*
870  * Traverse the index, find every entry that matches according to
871  * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
872  * number of traversed entries.
873  *
874  * If select_mask is non-zero, only entries whose ce_flags has on of
875  * those bits enabled are traversed.
876  *
877  * cache        : pointer to an index entry
878  * prefix_len   : an offset to its path
879  *
880  * The current path ("prefix") including the trailing '/' is
881  *   cache[0]->name[0..(prefix_len-1)]
882  * Top level path has prefix_len zero.
883  */
884 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
885                             struct strbuf *prefix,
886                             int select_mask, int clear_mask,
887                             struct exclude_list *el, int defval)
888 {
889         struct cache_entry **cache_end = cache + nr;
890
891         /*
892          * Process all entries that have the given prefix and meet
893          * select_mask condition
894          */
895         while(cache != cache_end) {
896                 struct cache_entry *ce = *cache;
897                 const char *name, *slash;
898                 int len, dtype, ret;
899
900                 if (select_mask && !(ce->ce_flags & select_mask)) {
901                         cache++;
902                         continue;
903                 }
904
905                 if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
906                         break;
907
908                 name = ce->name + prefix->len;
909                 slash = strchr(name, '/');
910
911                 /* If it's a directory, try whole directory match first */
912                 if (slash) {
913                         int processed;
914
915                         len = slash - name;
916                         strbuf_add(prefix, name, len);
917
918                         processed = clear_ce_flags_dir(cache, cache_end - cache,
919                                                        prefix,
920                                                        prefix->buf + prefix->len - len,
921                                                        select_mask, clear_mask,
922                                                        el, defval);
923
924                         /* clear_c_f_dir eats a whole dir already? */
925                         if (processed) {
926                                 cache += processed;
927                                 strbuf_setlen(prefix, prefix->len - len);
928                                 continue;
929                         }
930
931                         strbuf_addch(prefix, '/');
932                         cache += clear_ce_flags_1(cache, cache_end - cache,
933                                                   prefix,
934                                                   select_mask, clear_mask, el, defval);
935                         strbuf_setlen(prefix, prefix->len - len - 1);
936                         continue;
937                 }
938
939                 /* Non-directory */
940                 dtype = ce_to_dtype(ce);
941                 ret = is_excluded_from_list(ce->name, ce_namelen(ce),
942                                             name, &dtype, el);
943                 if (ret < 0)
944                         ret = defval;
945                 if (ret > 0)
946                         ce->ce_flags &= ~clear_mask;
947                 cache++;
948         }
949         return nr - (cache_end - cache);
950 }
951
952 static int clear_ce_flags(struct cache_entry **cache, int nr,
953                             int select_mask, int clear_mask,
954                             struct exclude_list *el)
955 {
956         static struct strbuf prefix = STRBUF_INIT;
957
958         strbuf_reset(&prefix);
959
960         return clear_ce_flags_1(cache, nr,
961                                 &prefix,
962                                 select_mask, clear_mask,
963                                 el, 0);
964 }
965
966 /*
967  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
968  */
969 static void mark_new_skip_worktree(struct exclude_list *el,
970                                    struct index_state *the_index,
971                                    int select_flag, int skip_wt_flag)
972 {
973         int i;
974
975         /*
976          * 1. Pretend the narrowest worktree: only unmerged entries
977          * are checked out
978          */
979         for (i = 0; i < the_index->cache_nr; i++) {
980                 struct cache_entry *ce = the_index->cache[i];
981
982                 if (select_flag && !(ce->ce_flags & select_flag))
983                         continue;
984
985                 if (!ce_stage(ce))
986                         ce->ce_flags |= skip_wt_flag;
987                 else
988                         ce->ce_flags &= ~skip_wt_flag;
989         }
990
991         /*
992          * 2. Widen worktree according to sparse-checkout file.
993          * Matched entries will have skip_wt_flag cleared (i.e. "in")
994          */
995         clear_ce_flags(the_index->cache, the_index->cache_nr,
996                        select_flag, skip_wt_flag, el);
997 }
998
999 static int verify_absent(const struct cache_entry *,
1000                          enum unpack_trees_error_types,
1001                          struct unpack_trees_options *);
1002 /*
1003  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1004  * resulting index, -2 on failure to reflect the changes to the work tree.
1005  *
1006  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1007  */
1008 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1009 {
1010         int i, ret;
1011         static struct cache_entry *dfc;
1012         struct exclude_list el;
1013
1014         if (len > MAX_UNPACK_TREES)
1015                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1016         memset(&state, 0, sizeof(state));
1017         state.base_dir = "";
1018         state.force = 1;
1019         state.quiet = 1;
1020         state.refresh_cache = 1;
1021         state.istate = &o->result;
1022
1023         memset(&el, 0, sizeof(el));
1024         if (!core_apply_sparse_checkout || !o->update)
1025                 o->skip_sparse_checkout = 1;
1026         if (!o->skip_sparse_checkout) {
1027                 if (add_excludes_from_file_to_list(git_path("info/sparse-checkout"), "", 0, &el, 0) < 0)
1028                         o->skip_sparse_checkout = 1;
1029                 else
1030                         o->el = &el;
1031         }
1032
1033         memset(&o->result, 0, sizeof(o->result));
1034         o->result.initialized = 1;
1035         o->result.timestamp.sec = o->src_index->timestamp.sec;
1036         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1037         o->result.version = o->src_index->version;
1038         o->result.split_index = o->src_index->split_index;
1039         if (o->result.split_index)
1040                 o->result.split_index->refcount++;
1041         hashcpy(o->result.sha1, o->src_index->sha1);
1042         o->merge_size = len;
1043         mark_all_ce_unused(o->src_index);
1044
1045         /*
1046          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1047          */
1048         if (!o->skip_sparse_checkout)
1049                 mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1050
1051         if (!dfc)
1052                 dfc = xcalloc(1, cache_entry_size(0));
1053         o->df_conflict_entry = dfc;
1054
1055         if (len) {
1056                 const char *prefix = o->prefix ? o->prefix : "";
1057                 struct traverse_info info;
1058
1059                 setup_traverse_info(&info, prefix);
1060                 info.fn = unpack_callback;
1061                 info.data = o;
1062                 info.show_all_errors = o->show_all_errors;
1063                 info.pathspec = o->pathspec;
1064
1065                 if (o->prefix) {
1066                         /*
1067                          * Unpack existing index entries that sort before the
1068                          * prefix the tree is spliced into.  Note that o->merge
1069                          * is always true in this case.
1070                          */
1071                         while (1) {
1072                                 struct cache_entry *ce = next_cache_entry(o);
1073                                 if (!ce)
1074                                         break;
1075                                 if (ce_in_traverse_path(ce, &info))
1076                                         break;
1077                                 if (unpack_index_entry(ce, o) < 0)
1078                                         goto return_failed;
1079                         }
1080                 }
1081
1082                 if (traverse_trees(len, t, &info) < 0)
1083                         goto return_failed;
1084         }
1085
1086         /* Any left-over entries in the index? */
1087         if (o->merge) {
1088                 while (1) {
1089                         struct cache_entry *ce = next_cache_entry(o);
1090                         if (!ce)
1091                                 break;
1092                         if (unpack_index_entry(ce, o) < 0)
1093                                 goto return_failed;
1094                 }
1095         }
1096         mark_all_ce_unused(o->src_index);
1097
1098         if (o->trivial_merges_only && o->nontrivial_merge) {
1099                 ret = unpack_failed(o, "Merge requires file-level merging");
1100                 goto done;
1101         }
1102
1103         if (!o->skip_sparse_checkout) {
1104                 int empty_worktree = 1;
1105
1106                 /*
1107                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1108                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1109                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1110                  */
1111                 mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1112
1113                 ret = 0;
1114                 for (i = 0; i < o->result.cache_nr; i++) {
1115                         struct cache_entry *ce = o->result.cache[i];
1116
1117                         /*
1118                          * Entries marked with CE_ADDED in merged_entry() do not have
1119                          * verify_absent() check (the check is effectively disabled
1120                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1121                          *
1122                          * Do the real check now because we have had
1123                          * correct CE_NEW_SKIP_WORKTREE
1124                          */
1125                         if (ce->ce_flags & CE_ADDED &&
1126                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1127                                 if (!o->show_all_errors)
1128                                         goto return_failed;
1129                                 ret = -1;
1130                         }
1131
1132                         if (apply_sparse_checkout(&o->result, ce, o)) {
1133                                 if (!o->show_all_errors)
1134                                         goto return_failed;
1135                                 ret = -1;
1136                         }
1137                         if (!ce_skip_worktree(ce))
1138                                 empty_worktree = 0;
1139
1140                 }
1141                 if (ret < 0)
1142                         goto return_failed;
1143                 /*
1144                  * Sparse checkout is meant to narrow down checkout area
1145                  * but it does not make sense to narrow down to empty working
1146                  * tree. This is usually a mistake in sparse checkout rules.
1147                  * Do not allow users to do that.
1148                  */
1149                 if (o->result.cache_nr && empty_worktree) {
1150                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1151                         goto done;
1152                 }
1153         }
1154
1155         o->src_index = NULL;
1156         ret = check_updates(o) ? (-2) : 0;
1157         if (o->dst_index) {
1158                 discard_index(o->dst_index);
1159                 *o->dst_index = o->result;
1160         } else {
1161                 discard_index(&o->result);
1162         }
1163
1164 done:
1165         clear_exclude_list(&el);
1166         return ret;
1167
1168 return_failed:
1169         if (o->show_all_errors)
1170                 display_error_msgs(o);
1171         mark_all_ce_unused(o->src_index);
1172         ret = unpack_failed(o, NULL);
1173         if (o->exiting_early)
1174                 ret = 0;
1175         goto done;
1176 }
1177
1178 /* Here come the merge functions */
1179
1180 static int reject_merge(const struct cache_entry *ce,
1181                         struct unpack_trees_options *o)
1182 {
1183         return o->gently ? -1 :
1184                 add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1185 }
1186
1187 static int same(const struct cache_entry *a, const struct cache_entry *b)
1188 {
1189         if (!!a != !!b)
1190                 return 0;
1191         if (!a && !b)
1192                 return 1;
1193         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1194                 return 0;
1195         return a->ce_mode == b->ce_mode &&
1196                !hashcmp(a->sha1, b->sha1);
1197 }
1198
1199
1200 /*
1201  * When a CE gets turned into an unmerged entry, we
1202  * want it to be up-to-date
1203  */
1204 static int verify_uptodate_1(const struct cache_entry *ce,
1205                              struct unpack_trees_options *o,
1206                              enum unpack_trees_error_types error_type)
1207 {
1208         struct stat st;
1209
1210         if (o->index_only)
1211                 return 0;
1212
1213         /*
1214          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1215          * if this entry is truly up-to-date because this file may be
1216          * overwritten.
1217          */
1218         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1219                 ; /* keep checking */
1220         else if (o->reset || ce_uptodate(ce))
1221                 return 0;
1222
1223         if (!lstat(ce->name, &st)) {
1224                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1225                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1226                 if (!changed)
1227                         return 0;
1228                 /*
1229                  * NEEDSWORK: the current default policy is to allow
1230                  * submodule to be out of sync wrt the superproject
1231                  * index.  This needs to be tightened later for
1232                  * submodules that are marked to be automatically
1233                  * checked out.
1234                  */
1235                 if (S_ISGITLINK(ce->ce_mode))
1236                         return 0;
1237                 errno = 0;
1238         }
1239         if (errno == ENOENT)
1240                 return 0;
1241         return o->gently ? -1 :
1242                 add_rejected_path(o, error_type, ce->name);
1243 }
1244
1245 static int verify_uptodate(const struct cache_entry *ce,
1246                            struct unpack_trees_options *o)
1247 {
1248         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1249                 return 0;
1250         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1251 }
1252
1253 static int verify_uptodate_sparse(const struct cache_entry *ce,
1254                                   struct unpack_trees_options *o)
1255 {
1256         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1257 }
1258
1259 static void invalidate_ce_path(const struct cache_entry *ce,
1260                                struct unpack_trees_options *o)
1261 {
1262         if (ce)
1263                 cache_tree_invalidate_path(o->src_index, ce->name);
1264 }
1265
1266 /*
1267  * Check that checking out ce->sha1 in subdir ce->name is not
1268  * going to overwrite any working files.
1269  *
1270  * Currently, git does not checkout subprojects during a superproject
1271  * checkout, so it is not going to overwrite anything.
1272  */
1273 static int verify_clean_submodule(const struct cache_entry *ce,
1274                                   enum unpack_trees_error_types error_type,
1275                                   struct unpack_trees_options *o)
1276 {
1277         return 0;
1278 }
1279
1280 static int verify_clean_subdirectory(const struct cache_entry *ce,
1281                                      enum unpack_trees_error_types error_type,
1282                                      struct unpack_trees_options *o)
1283 {
1284         /*
1285          * we are about to extract "ce->name"; we would not want to lose
1286          * anything in the existing directory there.
1287          */
1288         int namelen;
1289         int i;
1290         struct dir_struct d;
1291         char *pathbuf;
1292         int cnt = 0;
1293         unsigned char sha1[20];
1294
1295         if (S_ISGITLINK(ce->ce_mode) &&
1296             resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
1297                 /* If we are not going to update the submodule, then
1298                  * we don't care.
1299                  */
1300                 if (!hashcmp(sha1, ce->sha1))
1301                         return 0;
1302                 return verify_clean_submodule(ce, error_type, o);
1303         }
1304
1305         /*
1306          * First let's make sure we do not have a local modification
1307          * in that directory.
1308          */
1309         namelen = ce_namelen(ce);
1310         for (i = locate_in_src_index(ce, o);
1311              i < o->src_index->cache_nr;
1312              i++) {
1313                 struct cache_entry *ce2 = o->src_index->cache[i];
1314                 int len = ce_namelen(ce2);
1315                 if (len < namelen ||
1316                     strncmp(ce->name, ce2->name, namelen) ||
1317                     ce2->name[namelen] != '/')
1318                         break;
1319                 /*
1320                  * ce2->name is an entry in the subdirectory to be
1321                  * removed.
1322                  */
1323                 if (!ce_stage(ce2)) {
1324                         if (verify_uptodate(ce2, o))
1325                                 return -1;
1326                         add_entry(o, ce2, CE_REMOVE, 0);
1327                         mark_ce_used(ce2, o);
1328                 }
1329                 cnt++;
1330         }
1331
1332         /*
1333          * Then we need to make sure that we do not lose a locally
1334          * present file that is not ignored.
1335          */
1336         pathbuf = xmalloc(namelen + 2);
1337         memcpy(pathbuf, ce->name, namelen);
1338         strcpy(pathbuf+namelen, "/");
1339
1340         memset(&d, 0, sizeof(d));
1341         if (o->dir)
1342                 d.exclude_per_dir = o->dir->exclude_per_dir;
1343         i = read_directory(&d, pathbuf, namelen+1, NULL);
1344         if (i)
1345                 return o->gently ? -1 :
1346                         add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1347         free(pathbuf);
1348         return cnt;
1349 }
1350
1351 /*
1352  * This gets called when there was no index entry for the tree entry 'dst',
1353  * but we found a file in the working tree that 'lstat()' said was fine,
1354  * and we're on a case-insensitive filesystem.
1355  *
1356  * See if we can find a case-insensitive match in the index that also
1357  * matches the stat information, and assume it's that other file!
1358  */
1359 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1360 {
1361         const struct cache_entry *src;
1362
1363         src = index_file_exists(o->src_index, name, len, 1);
1364         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1365 }
1366
1367 static int check_ok_to_remove(const char *name, int len, int dtype,
1368                               const struct cache_entry *ce, struct stat *st,
1369                               enum unpack_trees_error_types error_type,
1370                               struct unpack_trees_options *o)
1371 {
1372         const struct cache_entry *result;
1373
1374         /*
1375          * It may be that the 'lstat()' succeeded even though
1376          * target 'ce' was absent, because there is an old
1377          * entry that is different only in case..
1378          *
1379          * Ignore that lstat() if it matches.
1380          */
1381         if (ignore_case && icase_exists(o, name, len, st))
1382                 return 0;
1383
1384         if (o->dir &&
1385             is_excluded(o->dir, name, &dtype))
1386                 /*
1387                  * ce->name is explicitly excluded, so it is Ok to
1388                  * overwrite it.
1389                  */
1390                 return 0;
1391         if (S_ISDIR(st->st_mode)) {
1392                 /*
1393                  * We are checking out path "foo" and
1394                  * found "foo/." in the working tree.
1395                  * This is tricky -- if we have modified
1396                  * files that are in "foo/" we would lose
1397                  * them.
1398                  */
1399                 if (verify_clean_subdirectory(ce, error_type, o) < 0)
1400                         return -1;
1401                 return 0;
1402         }
1403
1404         /*
1405          * The previous round may already have decided to
1406          * delete this path, which is in a subdirectory that
1407          * is being replaced with a blob.
1408          */
1409         result = index_file_exists(&o->result, name, len, 0);
1410         if (result) {
1411                 if (result->ce_flags & CE_REMOVE)
1412                         return 0;
1413         }
1414
1415         return o->gently ? -1 :
1416                 add_rejected_path(o, error_type, name);
1417 }
1418
1419 /*
1420  * We do not want to remove or overwrite a working tree file that
1421  * is not tracked, unless it is ignored.
1422  */
1423 static int verify_absent_1(const struct cache_entry *ce,
1424                            enum unpack_trees_error_types error_type,
1425                            struct unpack_trees_options *o)
1426 {
1427         int len;
1428         struct stat st;
1429
1430         if (o->index_only || o->reset || !o->update)
1431                 return 0;
1432
1433         len = check_leading_path(ce->name, ce_namelen(ce));
1434         if (!len)
1435                 return 0;
1436         else if (len > 0) {
1437                 char path[PATH_MAX + 1];
1438                 memcpy(path, ce->name, len);
1439                 path[len] = 0;
1440                 if (lstat(path, &st))
1441                         return error("cannot stat '%s': %s", path,
1442                                         strerror(errno));
1443
1444                 return check_ok_to_remove(path, len, DT_UNKNOWN, NULL, &st,
1445                                 error_type, o);
1446         } else if (lstat(ce->name, &st)) {
1447                 if (errno != ENOENT)
1448                         return error("cannot stat '%s': %s", ce->name,
1449                                      strerror(errno));
1450                 return 0;
1451         } else {
1452                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1453                                           ce_to_dtype(ce), ce, &st,
1454                                           error_type, o);
1455         }
1456 }
1457
1458 static int verify_absent(const struct cache_entry *ce,
1459                          enum unpack_trees_error_types error_type,
1460                          struct unpack_trees_options *o)
1461 {
1462         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1463                 return 0;
1464         return verify_absent_1(ce, error_type, o);
1465 }
1466
1467 static int verify_absent_sparse(const struct cache_entry *ce,
1468                                 enum unpack_trees_error_types error_type,
1469                                 struct unpack_trees_options *o)
1470 {
1471         enum unpack_trees_error_types orphaned_error = error_type;
1472         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1473                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1474
1475         return verify_absent_1(ce, orphaned_error, o);
1476 }
1477
1478 static int merged_entry(const struct cache_entry *ce,
1479                         const struct cache_entry *old,
1480                         struct unpack_trees_options *o)
1481 {
1482         int update = CE_UPDATE;
1483         struct cache_entry *merge = dup_entry(ce);
1484
1485         if (!old) {
1486                 /*
1487                  * New index entries. In sparse checkout, the following
1488                  * verify_absent() will be delayed until after
1489                  * traverse_trees() finishes in unpack_trees(), then:
1490                  *
1491                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1492                  *  - verify_absent() be called again, this time with
1493                  *    correct CE_NEW_SKIP_WORKTREE
1494                  *
1495                  * verify_absent() call here does nothing in sparse
1496                  * checkout (i.e. o->skip_sparse_checkout == 0)
1497                  */
1498                 update |= CE_ADDED;
1499                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1500
1501                 if (verify_absent(merge,
1502                                   ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1503                         free(merge);
1504                         return -1;
1505                 }
1506                 invalidate_ce_path(merge, o);
1507         } else if (!(old->ce_flags & CE_CONFLICTED)) {
1508                 /*
1509                  * See if we can re-use the old CE directly?
1510                  * That way we get the uptodate stat info.
1511                  *
1512                  * This also removes the UPDATE flag on a match; otherwise
1513                  * we will end up overwriting local changes in the work tree.
1514                  */
1515                 if (same(old, merge)) {
1516                         copy_cache_entry(merge, old);
1517                         update = 0;
1518                 } else {
1519                         if (verify_uptodate(old, o)) {
1520                                 free(merge);
1521                                 return -1;
1522                         }
1523                         /* Migrate old flags over */
1524                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1525                         invalidate_ce_path(old, o);
1526                 }
1527         } else {
1528                 /*
1529                  * Previously unmerged entry left as an existence
1530                  * marker by read_index_unmerged();
1531                  */
1532                 invalidate_ce_path(old, o);
1533         }
1534
1535         do_add_entry(o, merge, update, CE_STAGEMASK);
1536         return 1;
1537 }
1538
1539 static int deleted_entry(const struct cache_entry *ce,
1540                          const struct cache_entry *old,
1541                          struct unpack_trees_options *o)
1542 {
1543         /* Did it exist in the index? */
1544         if (!old) {
1545                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1546                         return -1;
1547                 return 0;
1548         }
1549         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1550                 return -1;
1551         add_entry(o, ce, CE_REMOVE, 0);
1552         invalidate_ce_path(ce, o);
1553         return 1;
1554 }
1555
1556 static int keep_entry(const struct cache_entry *ce,
1557                       struct unpack_trees_options *o)
1558 {
1559         add_entry(o, ce, 0, 0);
1560         return 1;
1561 }
1562
1563 #if DBRT_DEBUG
1564 static void show_stage_entry(FILE *o,
1565                              const char *label, const struct cache_entry *ce)
1566 {
1567         if (!ce)
1568                 fprintf(o, "%s (missing)\n", label);
1569         else
1570                 fprintf(o, "%s%06o %s %d\t%s\n",
1571                         label,
1572                         ce->ce_mode,
1573                         sha1_to_hex(ce->sha1),
1574                         ce_stage(ce),
1575                         ce->name);
1576 }
1577 #endif
1578
1579 int threeway_merge(const struct cache_entry * const *stages,
1580                    struct unpack_trees_options *o)
1581 {
1582         const struct cache_entry *index;
1583         const struct cache_entry *head;
1584         const struct cache_entry *remote = stages[o->head_idx + 1];
1585         int count;
1586         int head_match = 0;
1587         int remote_match = 0;
1588
1589         int df_conflict_head = 0;
1590         int df_conflict_remote = 0;
1591
1592         int any_anc_missing = 0;
1593         int no_anc_exists = 1;
1594         int i;
1595
1596         for (i = 1; i < o->head_idx; i++) {
1597                 if (!stages[i] || stages[i] == o->df_conflict_entry)
1598                         any_anc_missing = 1;
1599                 else
1600                         no_anc_exists = 0;
1601         }
1602
1603         index = stages[0];
1604         head = stages[o->head_idx];
1605
1606         if (head == o->df_conflict_entry) {
1607                 df_conflict_head = 1;
1608                 head = NULL;
1609         }
1610
1611         if (remote == o->df_conflict_entry) {
1612                 df_conflict_remote = 1;
1613                 remote = NULL;
1614         }
1615
1616         /*
1617          * First, if there's a #16 situation, note that to prevent #13
1618          * and #14.
1619          */
1620         if (!same(remote, head)) {
1621                 for (i = 1; i < o->head_idx; i++) {
1622                         if (same(stages[i], head)) {
1623                                 head_match = i;
1624                         }
1625                         if (same(stages[i], remote)) {
1626                                 remote_match = i;
1627                         }
1628                 }
1629         }
1630
1631         /*
1632          * We start with cases where the index is allowed to match
1633          * something other than the head: #14(ALT) and #2ALT, where it
1634          * is permitted to match the result instead.
1635          */
1636         /* #14, #14ALT, #2ALT */
1637         if (remote && !df_conflict_head && head_match && !remote_match) {
1638                 if (index && !same(index, remote) && !same(index, head))
1639                         return reject_merge(index, o);
1640                 return merged_entry(remote, index, o);
1641         }
1642         /*
1643          * If we have an entry in the index cache, then we want to
1644          * make sure that it matches head.
1645          */
1646         if (index && !same(index, head))
1647                 return reject_merge(index, o);
1648
1649         if (head) {
1650                 /* #5ALT, #15 */
1651                 if (same(head, remote))
1652                         return merged_entry(head, index, o);
1653                 /* #13, #3ALT */
1654                 if (!df_conflict_remote && remote_match && !head_match)
1655                         return merged_entry(head, index, o);
1656         }
1657
1658         /* #1 */
1659         if (!head && !remote && any_anc_missing)
1660                 return 0;
1661
1662         /*
1663          * Under the "aggressive" rule, we resolve mostly trivial
1664          * cases that we historically had git-merge-one-file resolve.
1665          */
1666         if (o->aggressive) {
1667                 int head_deleted = !head;
1668                 int remote_deleted = !remote;
1669                 const struct cache_entry *ce = NULL;
1670
1671                 if (index)
1672                         ce = index;
1673                 else if (head)
1674                         ce = head;
1675                 else if (remote)
1676                         ce = remote;
1677                 else {
1678                         for (i = 1; i < o->head_idx; i++) {
1679                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
1680                                         ce = stages[i];
1681                                         break;
1682                                 }
1683                         }
1684                 }
1685
1686                 /*
1687                  * Deleted in both.
1688                  * Deleted in one and unchanged in the other.
1689                  */
1690                 if ((head_deleted && remote_deleted) ||
1691                     (head_deleted && remote && remote_match) ||
1692                     (remote_deleted && head && head_match)) {
1693                         if (index)
1694                                 return deleted_entry(index, index, o);
1695                         if (ce && !head_deleted) {
1696                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1697                                         return -1;
1698                         }
1699                         return 0;
1700                 }
1701                 /*
1702                  * Added in both, identically.
1703                  */
1704                 if (no_anc_exists && head && remote && same(head, remote))
1705                         return merged_entry(head, index, o);
1706
1707         }
1708
1709         /* Below are "no merge" cases, which require that the index be
1710          * up-to-date to avoid the files getting overwritten with
1711          * conflict resolution files.
1712          */
1713         if (index) {
1714                 if (verify_uptodate(index, o))
1715                         return -1;
1716         }
1717
1718         o->nontrivial_merge = 1;
1719
1720         /* #2, #3, #4, #6, #7, #9, #10, #11. */
1721         count = 0;
1722         if (!head_match || !remote_match) {
1723                 for (i = 1; i < o->head_idx; i++) {
1724                         if (stages[i] && stages[i] != o->df_conflict_entry) {
1725                                 keep_entry(stages[i], o);
1726                                 count++;
1727                                 break;
1728                         }
1729                 }
1730         }
1731 #if DBRT_DEBUG
1732         else {
1733                 fprintf(stderr, "read-tree: warning #16 detected\n");
1734                 show_stage_entry(stderr, "head   ", stages[head_match]);
1735                 show_stage_entry(stderr, "remote ", stages[remote_match]);
1736         }
1737 #endif
1738         if (head) { count += keep_entry(head, o); }
1739         if (remote) { count += keep_entry(remote, o); }
1740         return count;
1741 }
1742
1743 /*
1744  * Two-way merge.
1745  *
1746  * The rule is to "carry forward" what is in the index without losing
1747  * information across a "fast-forward", favoring a successful merge
1748  * over a merge failure when it makes sense.  For details of the
1749  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
1750  *
1751  */
1752 int twoway_merge(const struct cache_entry * const *src,
1753                  struct unpack_trees_options *o)
1754 {
1755         const struct cache_entry *current = src[0];
1756         const struct cache_entry *oldtree = src[1];
1757         const struct cache_entry *newtree = src[2];
1758
1759         if (o->merge_size != 2)
1760                 return error("Cannot do a twoway merge of %d trees",
1761                              o->merge_size);
1762
1763         if (oldtree == o->df_conflict_entry)
1764                 oldtree = NULL;
1765         if (newtree == o->df_conflict_entry)
1766                 newtree = NULL;
1767
1768         if (current) {
1769                 if (current->ce_flags & CE_CONFLICTED) {
1770                         if (same(oldtree, newtree) || o->reset) {
1771                                 if (!newtree)
1772                                         return deleted_entry(current, current, o);
1773                                 else
1774                                         return merged_entry(newtree, current, o);
1775                         }
1776                         return reject_merge(current, o);
1777                 } else if ((!oldtree && !newtree) || /* 4 and 5 */
1778                          (!oldtree && newtree &&
1779                           same(current, newtree)) || /* 6 and 7 */
1780                          (oldtree && newtree &&
1781                           same(oldtree, newtree)) || /* 14 and 15 */
1782                          (oldtree && newtree &&
1783                           !same(oldtree, newtree) && /* 18 and 19 */
1784                           same(current, newtree))) {
1785                         return keep_entry(current, o);
1786                 } else if (oldtree && !newtree && same(current, oldtree)) {
1787                         /* 10 or 11 */
1788                         return deleted_entry(oldtree, current, o);
1789                 } else if (oldtree && newtree &&
1790                          same(current, oldtree) && !same(current, newtree)) {
1791                         /* 20 or 21 */
1792                         return merged_entry(newtree, current, o);
1793                 } else
1794                         return reject_merge(current, o);
1795         }
1796         else if (newtree) {
1797                 if (oldtree && !o->initial_checkout) {
1798                         /*
1799                          * deletion of the path was staged;
1800                          */
1801                         if (same(oldtree, newtree))
1802                                 return 1;
1803                         return reject_merge(oldtree, o);
1804                 }
1805                 return merged_entry(newtree, current, o);
1806         }
1807         return deleted_entry(oldtree, current, o);
1808 }
1809
1810 /*
1811  * Bind merge.
1812  *
1813  * Keep the index entries at stage0, collapse stage1 but make sure
1814  * stage0 does not have anything there.
1815  */
1816 int bind_merge(const struct cache_entry * const *src,
1817                struct unpack_trees_options *o)
1818 {
1819         const struct cache_entry *old = src[0];
1820         const struct cache_entry *a = src[1];
1821
1822         if (o->merge_size != 1)
1823                 return error("Cannot do a bind merge of %d trees",
1824                              o->merge_size);
1825         if (a && old)
1826                 return o->gently ? -1 :
1827                         error(ERRORMSG(o, ERROR_BIND_OVERLAP), a->name, old->name);
1828         if (!a)
1829                 return keep_entry(old, o);
1830         else
1831                 return merged_entry(a, NULL, o);
1832 }
1833
1834 /*
1835  * One-way merge.
1836  *
1837  * The rule is:
1838  * - take the stat information from stage0, take the data from stage1
1839  */
1840 int oneway_merge(const struct cache_entry * const *src,
1841                  struct unpack_trees_options *o)
1842 {
1843         const struct cache_entry *old = src[0];
1844         const struct cache_entry *a = src[1];
1845
1846         if (o->merge_size != 1)
1847                 return error("Cannot do a oneway merge of %d trees",
1848                              o->merge_size);
1849
1850         if (!a || a == o->df_conflict_entry)
1851                 return deleted_entry(old, old, o);
1852
1853         if (old && same(old, a)) {
1854                 int update = 0;
1855                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
1856                         struct stat st;
1857                         if (lstat(old->name, &st) ||
1858                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
1859                                 update |= CE_UPDATE;
1860                 }
1861                 add_entry(o, old, update, 0);
1862                 return 0;
1863         }
1864         return merged_entry(a, old, o);
1865 }