Merge branch 'jh/filter-empty-contents'
[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         const char *cmd2 = strcmp(cmd, "checkout") ? cmd : "switch branches";
62
63         if (advice_commit_before_merge)
64                 msg = "Your local changes to the following files would be overwritten by %s:\n%%s"
65                         "Please, commit your changes or stash them before you can %s.";
66         else
67                 msg = "Your local changes to the following files would be overwritten by %s:\n%%s";
68         msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
69                 xstrfmt(msg, cmd, cmd2);
70
71         msgs[ERROR_NOT_UPTODATE_DIR] =
72                 "Updating the following directories would lose untracked files in it:\n%s";
73
74         if (advice_commit_before_merge)
75                 msg = "The following untracked working tree files would be %s by %s:\n%%s"
76                         "Please move or remove them before you can %s.";
77         else
78                 msg = "The following untracked working tree files would be %s by %s:\n%%s";
79
80         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = xstrfmt(msg, "removed", cmd, cmd2);
81         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = xstrfmt(msg, "overwritten", cmd, cmd2);
82
83         /*
84          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
85          * cannot easily display it as a list.
86          */
87         msgs[ERROR_BIND_OVERLAP] = "Entry '%s' overlaps with '%s'.  Cannot bind.";
88
89         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
90                 "Cannot update sparse checkout: the following entries are not up-to-date:\n%s";
91         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
92                 "The following Working tree files would be overwritten by sparse checkout update:\n%s";
93         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
94                 "The following Working tree files would be removed by sparse checkout update:\n%s";
95
96         opts->show_all_errors = 1;
97         /* rejected paths may not have a static buffer */
98         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
99                 opts->unpack_rejects[i].strdup_strings = 1;
100 }
101
102 static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
103                          unsigned int set, unsigned int clear)
104 {
105         clear |= CE_HASHED;
106
107         if (set & CE_REMOVE)
108                 set |= CE_WT_REMOVE;
109
110         ce->ce_flags = (ce->ce_flags & ~clear) | set;
111         return add_index_entry(&o->result, ce,
112                                ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
113 }
114
115 static struct cache_entry *dup_entry(const struct cache_entry *ce)
116 {
117         unsigned int size = ce_size(ce);
118         struct cache_entry *new = xmalloc(size);
119
120         memcpy(new, ce, size);
121         return new;
122 }
123
124 static void add_entry(struct unpack_trees_options *o,
125                       const struct cache_entry *ce,
126                       unsigned int set, unsigned int clear)
127 {
128         do_add_entry(o, dup_entry(ce), set, clear);
129 }
130
131 /*
132  * add error messages on path <path>
133  * corresponding to the type <e> with the message <msg>
134  * indicating if it should be display in porcelain or not
135  */
136 static int add_rejected_path(struct unpack_trees_options *o,
137                              enum unpack_trees_error_types e,
138                              const char *path)
139 {
140         if (!o->show_all_errors)
141                 return error(ERRORMSG(o, e), path);
142
143         /*
144          * Otherwise, insert in a list for future display by
145          * display_error_msgs()
146          */
147         string_list_append(&o->unpack_rejects[e], path);
148         return -1;
149 }
150
151 /*
152  * display all the error messages stored in a nice way
153  */
154 static void display_error_msgs(struct unpack_trees_options *o)
155 {
156         int e, i;
157         int something_displayed = 0;
158         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
159                 struct string_list *rejects = &o->unpack_rejects[e];
160                 if (rejects->nr > 0) {
161                         struct strbuf path = STRBUF_INIT;
162                         something_displayed = 1;
163                         for (i = 0; i < rejects->nr; i++)
164                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
165                         error(ERRORMSG(o, e), path.buf);
166                         strbuf_release(&path);
167                 }
168                 string_list_clear(rejects, 0);
169         }
170         if (something_displayed)
171                 fprintf(stderr, "Aborting\n");
172 }
173
174 /*
175  * Unlink the last component and schedule the leading directories for
176  * removal, such that empty directories get removed.
177  */
178 static void unlink_entry(const struct cache_entry *ce)
179 {
180         if (!check_leading_path(ce->name, ce_namelen(ce)))
181                 return;
182         if (remove_or_warn(ce->ce_mode, ce->name))
183                 return;
184         schedule_dir_for_removal(ce->name, ce_namelen(ce));
185 }
186
187 static struct checkout state;
188 static int check_updates(struct unpack_trees_options *o)
189 {
190         unsigned cnt = 0, total = 0;
191         struct progress *progress = NULL;
192         struct index_state *index = &o->result;
193         int i;
194         int errs = 0;
195
196         if (o->update && o->verbose_update) {
197                 for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
198                         const struct cache_entry *ce = index->cache[cnt];
199                         if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
200                                 total++;
201                 }
202
203                 progress = start_progress_delay(_("Checking out files"),
204                                                 total, 50, 1);
205                 cnt = 0;
206         }
207
208         if (o->update)
209                 git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
210         for (i = 0; i < index->cache_nr; i++) {
211                 const struct cache_entry *ce = index->cache[i];
212
213                 if (ce->ce_flags & CE_WT_REMOVE) {
214                         display_progress(progress, ++cnt);
215                         if (o->update && !o->dry_run)
216                                 unlink_entry(ce);
217                         continue;
218                 }
219         }
220         remove_marked_cache_entries(&o->result);
221         remove_scheduled_dirs();
222
223         for (i = 0; i < index->cache_nr; i++) {
224                 struct cache_entry *ce = index->cache[i];
225
226                 if (ce->ce_flags & CE_UPDATE) {
227                         display_progress(progress, ++cnt);
228                         ce->ce_flags &= ~CE_UPDATE;
229                         if (o->update && !o->dry_run) {
230                                 errs |= checkout_entry(ce, &state, NULL);
231                         }
232                 }
233         }
234         stop_progress(&progress);
235         if (o->update)
236                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
237         return errs != 0;
238 }
239
240 static int verify_uptodate_sparse(const struct cache_entry *ce,
241                                   struct unpack_trees_options *o);
242 static int verify_absent_sparse(const struct cache_entry *ce,
243                                 enum unpack_trees_error_types,
244                                 struct unpack_trees_options *o);
245
246 static int apply_sparse_checkout(struct index_state *istate,
247                                  struct cache_entry *ce,
248                                  struct unpack_trees_options *o)
249 {
250         int was_skip_worktree = ce_skip_worktree(ce);
251
252         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
253                 ce->ce_flags |= CE_SKIP_WORKTREE;
254         else
255                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
256         if (was_skip_worktree != ce_skip_worktree(ce)) {
257                 ce->ce_flags |= CE_UPDATE_IN_BASE;
258                 istate->cache_changed |= CE_ENTRY_CHANGED;
259         }
260
261         /*
262          * if (!was_skip_worktree && !ce_skip_worktree()) {
263          *      This is perfectly normal. Move on;
264          * }
265          */
266
267         /*
268          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
269          * area as a result of ce_skip_worktree() shortcuts in
270          * verify_absent() and verify_uptodate().
271          * Make sure they don't modify worktree if they are already
272          * outside checkout area
273          */
274         if (was_skip_worktree && ce_skip_worktree(ce)) {
275                 ce->ce_flags &= ~CE_UPDATE;
276
277                 /*
278                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
279                  * on to get that file removed from both index and worktree.
280                  * If that file is already outside worktree area, don't
281                  * bother remove it.
282                  */
283                 if (ce->ce_flags & CE_REMOVE)
284                         ce->ce_flags &= ~CE_WT_REMOVE;
285         }
286
287         if (!was_skip_worktree && ce_skip_worktree(ce)) {
288                 /*
289                  * If CE_UPDATE is set, verify_uptodate() must be called already
290                  * also stat info may have lost after merged_entry() so calling
291                  * verify_uptodate() again may fail
292                  */
293                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
294                         return -1;
295                 ce->ce_flags |= CE_WT_REMOVE;
296         }
297         if (was_skip_worktree && !ce_skip_worktree(ce)) {
298                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
299                         return -1;
300                 ce->ce_flags |= CE_UPDATE;
301         }
302         return 0;
303 }
304
305 static inline int call_unpack_fn(const struct cache_entry * const *src,
306                                  struct unpack_trees_options *o)
307 {
308         int ret = o->fn(src, o);
309         if (ret > 0)
310                 ret = 0;
311         return ret;
312 }
313
314 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
315 {
316         ce->ce_flags |= CE_UNPACKED;
317
318         if (o->cache_bottom < o->src_index->cache_nr &&
319             o->src_index->cache[o->cache_bottom] == ce) {
320                 int bottom = o->cache_bottom;
321                 while (bottom < o->src_index->cache_nr &&
322                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
323                         bottom++;
324                 o->cache_bottom = bottom;
325         }
326 }
327
328 static void mark_all_ce_unused(struct index_state *index)
329 {
330         int i;
331         for (i = 0; i < index->cache_nr; i++)
332                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
333 }
334
335 static int locate_in_src_index(const struct cache_entry *ce,
336                                struct unpack_trees_options *o)
337 {
338         struct index_state *index = o->src_index;
339         int len = ce_namelen(ce);
340         int pos = index_name_pos(index, ce->name, len);
341         if (pos < 0)
342                 pos = -1 - pos;
343         return pos;
344 }
345
346 /*
347  * We call unpack_index_entry() with an unmerged cache entry
348  * only in diff-index, and it wants a single callback.  Skip
349  * the other unmerged entry with the same name.
350  */
351 static void mark_ce_used_same_name(struct cache_entry *ce,
352                                    struct unpack_trees_options *o)
353 {
354         struct index_state *index = o->src_index;
355         int len = ce_namelen(ce);
356         int pos;
357
358         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
359                 struct cache_entry *next = index->cache[pos];
360                 if (len != ce_namelen(next) ||
361                     memcmp(ce->name, next->name, len))
362                         break;
363                 mark_ce_used(next, o);
364         }
365 }
366
367 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
368 {
369         const struct index_state *index = o->src_index;
370         int pos = o->cache_bottom;
371
372         while (pos < index->cache_nr) {
373                 struct cache_entry *ce = index->cache[pos];
374                 if (!(ce->ce_flags & CE_UNPACKED))
375                         return ce;
376                 pos++;
377         }
378         return NULL;
379 }
380
381 static void add_same_unmerged(const struct cache_entry *ce,
382                               struct unpack_trees_options *o)
383 {
384         struct index_state *index = o->src_index;
385         int len = ce_namelen(ce);
386         int pos = index_name_pos(index, ce->name, len);
387
388         if (0 <= pos)
389                 die("programming error in a caller of mark_ce_used_same_name");
390         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
391                 struct cache_entry *next = index->cache[pos];
392                 if (len != ce_namelen(next) ||
393                     memcmp(ce->name, next->name, len))
394                         break;
395                 add_entry(o, next, 0, 0);
396                 mark_ce_used(next, o);
397         }
398 }
399
400 static int unpack_index_entry(struct cache_entry *ce,
401                               struct unpack_trees_options *o)
402 {
403         const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
404         int ret;
405
406         src[0] = ce;
407
408         mark_ce_used(ce, o);
409         if (ce_stage(ce)) {
410                 if (o->skip_unmerged) {
411                         add_entry(o, ce, 0, 0);
412                         return 0;
413                 }
414         }
415         ret = call_unpack_fn(src, o);
416         if (ce_stage(ce))
417                 mark_ce_used_same_name(ce, o);
418         return ret;
419 }
420
421 static int find_cache_pos(struct traverse_info *, const struct name_entry *);
422
423 static void restore_cache_bottom(struct traverse_info *info, int bottom)
424 {
425         struct unpack_trees_options *o = info->data;
426
427         if (o->diff_index_cached)
428                 return;
429         o->cache_bottom = bottom;
430 }
431
432 static int switch_cache_bottom(struct traverse_info *info)
433 {
434         struct unpack_trees_options *o = info->data;
435         int ret, pos;
436
437         if (o->diff_index_cached)
438                 return 0;
439         ret = o->cache_bottom;
440         pos = find_cache_pos(info->prev, &info->name);
441
442         if (pos < -1)
443                 o->cache_bottom = -2 - pos;
444         else if (pos < 0)
445                 o->cache_bottom = o->src_index->cache_nr;
446         return ret;
447 }
448
449 static int traverse_trees_recursive(int n, unsigned long dirmask,
450                                     unsigned long df_conflicts,
451                                     struct name_entry *names,
452                                     struct traverse_info *info)
453 {
454         int i, ret, bottom;
455         struct tree_desc t[MAX_UNPACK_TREES];
456         void *buf[MAX_UNPACK_TREES];
457         struct traverse_info newinfo;
458         struct name_entry *p;
459
460         p = names;
461         while (!p->mode)
462                 p++;
463
464         newinfo = *info;
465         newinfo.prev = info;
466         newinfo.pathspec = info->pathspec;
467         newinfo.name = *p;
468         newinfo.pathlen += tree_entry_len(p) + 1;
469         newinfo.df_conflicts |= df_conflicts;
470
471         for (i = 0; i < n; i++, dirmask >>= 1) {
472                 const unsigned char *sha1 = NULL;
473                 if (dirmask & 1)
474                         sha1 = names[i].sha1;
475                 buf[i] = fill_tree_descriptor(t+i, sha1);
476         }
477
478         bottom = switch_cache_bottom(&newinfo);
479         ret = traverse_trees(n, t, &newinfo);
480         restore_cache_bottom(&newinfo, bottom);
481
482         for (i = 0; i < n; i++)
483                 free(buf[i]);
484
485         return ret;
486 }
487
488 /*
489  * Compare the traverse-path to the cache entry without actually
490  * having to generate the textual representation of the traverse
491  * path.
492  *
493  * NOTE! This *only* compares up to the size of the traverse path
494  * itself - the caller needs to do the final check for the cache
495  * entry having more data at the end!
496  */
497 static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
498 {
499         int len, pathlen, ce_len;
500         const char *ce_name;
501
502         if (info->prev) {
503                 int cmp = do_compare_entry(ce, info->prev, &info->name);
504                 if (cmp)
505                         return cmp;
506         }
507         pathlen = info->pathlen;
508         ce_len = ce_namelen(ce);
509
510         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
511         if (ce_len < pathlen)
512                 return -1;
513
514         ce_len -= pathlen;
515         ce_name = ce->name + pathlen;
516
517         len = tree_entry_len(n);
518         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
519 }
520
521 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
522 {
523         int cmp = do_compare_entry(ce, info, n);
524         if (cmp)
525                 return cmp;
526
527         /*
528          * Even if the beginning compared identically, the ce should
529          * compare as bigger than a directory leading up to it!
530          */
531         return ce_namelen(ce) > traverse_path_len(info, n);
532 }
533
534 static int ce_in_traverse_path(const struct cache_entry *ce,
535                                const struct traverse_info *info)
536 {
537         if (!info->prev)
538                 return 1;
539         if (do_compare_entry(ce, info->prev, &info->name))
540                 return 0;
541         /*
542          * If ce (blob) is the same name as the path (which is a tree
543          * we will be descending into), it won't be inside it.
544          */
545         return (info->pathlen < ce_namelen(ce));
546 }
547
548 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
549 {
550         int len = traverse_path_len(info, n);
551         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
552
553         ce->ce_mode = create_ce_mode(n->mode);
554         ce->ce_flags = create_ce_flags(stage);
555         ce->ce_namelen = len;
556         hashcpy(ce->sha1, n->sha1);
557         make_traverse_path(ce->name, info, n);
558
559         return ce;
560 }
561
562 static int unpack_nondirectories(int n, unsigned long mask,
563                                  unsigned long dirmask,
564                                  struct cache_entry **src,
565                                  const struct name_entry *names,
566                                  const struct traverse_info *info)
567 {
568         int i;
569         struct unpack_trees_options *o = info->data;
570         unsigned long conflicts = info->df_conflicts | dirmask;
571
572         /* Do we have *only* directories? Nothing to do */
573         if (mask == dirmask && !src[0])
574                 return 0;
575
576         /*
577          * Ok, we've filled in up to any potential index entry in src[0],
578          * now do the rest.
579          */
580         for (i = 0; i < n; i++) {
581                 int stage;
582                 unsigned int bit = 1ul << i;
583                 if (conflicts & bit) {
584                         src[i + o->merge] = o->df_conflict_entry;
585                         continue;
586                 }
587                 if (!(mask & bit))
588                         continue;
589                 if (!o->merge)
590                         stage = 0;
591                 else if (i + 1 < o->head_idx)
592                         stage = 1;
593                 else if (i + 1 > o->head_idx)
594                         stage = 3;
595                 else
596                         stage = 2;
597                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
598         }
599
600         if (o->merge) {
601                 int rc = call_unpack_fn((const struct cache_entry * const *)src,
602                                         o);
603                 for (i = 0; i < n; i++) {
604                         struct cache_entry *ce = src[i + o->merge];
605                         if (ce != o->df_conflict_entry)
606                                 free(ce);
607                 }
608                 return rc;
609         }
610
611         for (i = 0; i < n; i++)
612                 if (src[i] && src[i] != o->df_conflict_entry)
613                         if (do_add_entry(o, src[i], 0, 0))
614                                 return -1;
615
616         return 0;
617 }
618
619 static int unpack_failed(struct unpack_trees_options *o, const char *message)
620 {
621         discard_index(&o->result);
622         if (!o->gently && !o->exiting_early) {
623                 if (message)
624                         return error("%s", message);
625                 return -1;
626         }
627         return -1;
628 }
629
630 /*
631  * The tree traversal is looking at name p.  If we have a matching entry,
632  * return it.  If name p is a directory in the index, do not return
633  * anything, as we will want to match it when the traversal descends into
634  * the directory.
635  */
636 static int find_cache_pos(struct traverse_info *info,
637                           const struct name_entry *p)
638 {
639         int pos;
640         struct unpack_trees_options *o = info->data;
641         struct index_state *index = o->src_index;
642         int pfxlen = info->pathlen;
643         int p_len = tree_entry_len(p);
644
645         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
646                 const struct cache_entry *ce = index->cache[pos];
647                 const char *ce_name, *ce_slash;
648                 int cmp, ce_len;
649
650                 if (ce->ce_flags & CE_UNPACKED) {
651                         /*
652                          * cache_bottom entry is already unpacked, so
653                          * we can never match it; don't check it
654                          * again.
655                          */
656                         if (pos == o->cache_bottom)
657                                 ++o->cache_bottom;
658                         continue;
659                 }
660                 if (!ce_in_traverse_path(ce, info))
661                         continue;
662                 ce_name = ce->name + pfxlen;
663                 ce_slash = strchr(ce_name, '/');
664                 if (ce_slash)
665                         ce_len = ce_slash - ce_name;
666                 else
667                         ce_len = ce_namelen(ce) - pfxlen;
668                 cmp = name_compare(p->path, p_len, ce_name, ce_len);
669                 /*
670                  * Exact match; if we have a directory we need to
671                  * delay returning it.
672                  */
673                 if (!cmp)
674                         return ce_slash ? -2 - pos : pos;
675                 if (0 < cmp)
676                         continue; /* keep looking */
677                 /*
678                  * ce_name sorts after p->path; could it be that we
679                  * have files under p->path directory in the index?
680                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
681                  * have "t/a" in the index.
682                  */
683                 if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
684                     ce_name[p_len] < '/')
685                         continue; /* keep looking */
686                 break;
687         }
688         return -1;
689 }
690
691 static struct cache_entry *find_cache_entry(struct traverse_info *info,
692                                             const struct name_entry *p)
693 {
694         int pos = find_cache_pos(info, p);
695         struct unpack_trees_options *o = info->data;
696
697         if (0 <= pos)
698                 return o->src_index->cache[pos];
699         else
700                 return NULL;
701 }
702
703 static void debug_path(struct traverse_info *info)
704 {
705         if (info->prev) {
706                 debug_path(info->prev);
707                 if (*info->prev->name.path)
708                         putchar('/');
709         }
710         printf("%s", info->name.path);
711 }
712
713 static void debug_name_entry(int i, struct name_entry *n)
714 {
715         printf("ent#%d %06o %s\n", i,
716                n->path ? n->mode : 0,
717                n->path ? n->path : "(missing)");
718 }
719
720 static void debug_unpack_callback(int n,
721                                   unsigned long mask,
722                                   unsigned long dirmask,
723                                   struct name_entry *names,
724                                   struct traverse_info *info)
725 {
726         int i;
727         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
728                mask, dirmask, n);
729         debug_path(info);
730         putchar('\n');
731         for (i = 0; i < n; i++)
732                 debug_name_entry(i, names + i);
733 }
734
735 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
736 {
737         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
738         struct unpack_trees_options *o = info->data;
739         const struct name_entry *p = names;
740
741         /* Find first entry with a real name (we could use "mask" too) */
742         while (!p->mode)
743                 p++;
744
745         if (o->debug_unpack)
746                 debug_unpack_callback(n, mask, dirmask, names, info);
747
748         /* Are we supposed to look at the index too? */
749         if (o->merge) {
750                 while (1) {
751                         int cmp;
752                         struct cache_entry *ce;
753
754                         if (o->diff_index_cached)
755                                 ce = next_cache_entry(o);
756                         else
757                                 ce = find_cache_entry(info, p);
758
759                         if (!ce)
760                                 break;
761                         cmp = compare_entry(ce, info, p);
762                         if (cmp < 0) {
763                                 if (unpack_index_entry(ce, o) < 0)
764                                         return unpack_failed(o, NULL);
765                                 continue;
766                         }
767                         if (!cmp) {
768                                 if (ce_stage(ce)) {
769                                         /*
770                                          * If we skip unmerged index
771                                          * entries, we'll skip this
772                                          * entry *and* the tree
773                                          * entries associated with it!
774                                          */
775                                         if (o->skip_unmerged) {
776                                                 add_same_unmerged(ce, o);
777                                                 return mask;
778                                         }
779                                 }
780                                 src[0] = ce;
781                         }
782                         break;
783                 }
784         }
785
786         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
787                 return -1;
788
789         if (o->merge && src[0]) {
790                 if (ce_stage(src[0]))
791                         mark_ce_used_same_name(src[0], o);
792                 else
793                         mark_ce_used(src[0], o);
794         }
795
796         /* Now handle any directories.. */
797         if (dirmask) {
798                 /* special case: "diff-index --cached" looking at a tree */
799                 if (o->diff_index_cached &&
800                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
801                         int matches;
802                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
803                                                                names, info);
804                         /*
805                          * Everything under the name matches; skip the
806                          * entire hierarchy.  diff_index_cached codepath
807                          * special cases D/F conflicts in such a way that
808                          * it does not do any look-ahead, so this is safe.
809                          */
810                         if (matches) {
811                                 o->cache_bottom += matches;
812                                 return mask;
813                         }
814                 }
815
816                 if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
817                                              names, info) < 0)
818                         return -1;
819                 return mask;
820         }
821
822         return mask;
823 }
824
825 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
826                             struct strbuf *prefix,
827                             int select_mask, int clear_mask,
828                             struct exclude_list *el, int defval);
829
830 /* Whole directory matching */
831 static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
832                               struct strbuf *prefix,
833                               char *basename,
834                               int select_mask, int clear_mask,
835                               struct exclude_list *el, int defval)
836 {
837         struct cache_entry **cache_end;
838         int dtype = DT_DIR;
839         int ret = is_excluded_from_list(prefix->buf, prefix->len,
840                                         basename, &dtype, el);
841         int rc;
842
843         strbuf_addch(prefix, '/');
844
845         /* If undecided, use matching result of parent dir in defval */
846         if (ret < 0)
847                 ret = defval;
848
849         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
850                 struct cache_entry *ce = *cache_end;
851                 if (strncmp(ce->name, prefix->buf, prefix->len))
852                         break;
853         }
854
855         /*
856          * TODO: check el, if there are no patterns that may conflict
857          * with ret (iow, we know in advance the incl/excl
858          * decision for the entire directory), clear flag here without
859          * calling clear_ce_flags_1(). That function will call
860          * the expensive is_excluded_from_list() on every entry.
861          */
862         rc = clear_ce_flags_1(cache, cache_end - cache,
863                               prefix,
864                               select_mask, clear_mask,
865                               el, ret);
866         strbuf_setlen(prefix, prefix->len - 1);
867         return rc;
868 }
869
870 /*
871  * Traverse the index, find every entry that matches according to
872  * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
873  * number of traversed entries.
874  *
875  * If select_mask is non-zero, only entries whose ce_flags has on of
876  * those bits enabled are traversed.
877  *
878  * cache        : pointer to an index entry
879  * prefix_len   : an offset to its path
880  *
881  * The current path ("prefix") including the trailing '/' is
882  *   cache[0]->name[0..(prefix_len-1)]
883  * Top level path has prefix_len zero.
884  */
885 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
886                             struct strbuf *prefix,
887                             int select_mask, int clear_mask,
888                             struct exclude_list *el, int defval)
889 {
890         struct cache_entry **cache_end = cache + nr;
891
892         /*
893          * Process all entries that have the given prefix and meet
894          * select_mask condition
895          */
896         while(cache != cache_end) {
897                 struct cache_entry *ce = *cache;
898                 const char *name, *slash;
899                 int len, dtype, ret;
900
901                 if (select_mask && !(ce->ce_flags & select_mask)) {
902                         cache++;
903                         continue;
904                 }
905
906                 if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
907                         break;
908
909                 name = ce->name + prefix->len;
910                 slash = strchr(name, '/');
911
912                 /* If it's a directory, try whole directory match first */
913                 if (slash) {
914                         int processed;
915
916                         len = slash - name;
917                         strbuf_add(prefix, name, len);
918
919                         processed = clear_ce_flags_dir(cache, cache_end - cache,
920                                                        prefix,
921                                                        prefix->buf + prefix->len - len,
922                                                        select_mask, clear_mask,
923                                                        el, defval);
924
925                         /* clear_c_f_dir eats a whole dir already? */
926                         if (processed) {
927                                 cache += processed;
928                                 strbuf_setlen(prefix, prefix->len - len);
929                                 continue;
930                         }
931
932                         strbuf_addch(prefix, '/');
933                         cache += clear_ce_flags_1(cache, cache_end - cache,
934                                                   prefix,
935                                                   select_mask, clear_mask, el, defval);
936                         strbuf_setlen(prefix, prefix->len - len - 1);
937                         continue;
938                 }
939
940                 /* Non-directory */
941                 dtype = ce_to_dtype(ce);
942                 ret = is_excluded_from_list(ce->name, ce_namelen(ce),
943                                             name, &dtype, el);
944                 if (ret < 0)
945                         ret = defval;
946                 if (ret > 0)
947                         ce->ce_flags &= ~clear_mask;
948                 cache++;
949         }
950         return nr - (cache_end - cache);
951 }
952
953 static int clear_ce_flags(struct cache_entry **cache, int nr,
954                             int select_mask, int clear_mask,
955                             struct exclude_list *el)
956 {
957         static struct strbuf prefix = STRBUF_INIT;
958
959         strbuf_reset(&prefix);
960
961         return clear_ce_flags_1(cache, nr,
962                                 &prefix,
963                                 select_mask, clear_mask,
964                                 el, 0);
965 }
966
967 /*
968  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
969  */
970 static void mark_new_skip_worktree(struct exclude_list *el,
971                                    struct index_state *the_index,
972                                    int select_flag, int skip_wt_flag)
973 {
974         int i;
975
976         /*
977          * 1. Pretend the narrowest worktree: only unmerged entries
978          * are checked out
979          */
980         for (i = 0; i < the_index->cache_nr; i++) {
981                 struct cache_entry *ce = the_index->cache[i];
982
983                 if (select_flag && !(ce->ce_flags & select_flag))
984                         continue;
985
986                 if (!ce_stage(ce))
987                         ce->ce_flags |= skip_wt_flag;
988                 else
989                         ce->ce_flags &= ~skip_wt_flag;
990         }
991
992         /*
993          * 2. Widen worktree according to sparse-checkout file.
994          * Matched entries will have skip_wt_flag cleared (i.e. "in")
995          */
996         clear_ce_flags(the_index->cache, the_index->cache_nr,
997                        select_flag, skip_wt_flag, el);
998 }
999
1000 static int verify_absent(const struct cache_entry *,
1001                          enum unpack_trees_error_types,
1002                          struct unpack_trees_options *);
1003 /*
1004  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1005  * resulting index, -2 on failure to reflect the changes to the work tree.
1006  *
1007  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1008  */
1009 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1010 {
1011         int i, ret;
1012         static struct cache_entry *dfc;
1013         struct exclude_list el;
1014
1015         if (len > MAX_UNPACK_TREES)
1016                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1017         memset(&state, 0, sizeof(state));
1018         state.base_dir = "";
1019         state.force = 1;
1020         state.quiet = 1;
1021         state.refresh_cache = 1;
1022         state.istate = &o->result;
1023
1024         memset(&el, 0, sizeof(el));
1025         if (!core_apply_sparse_checkout || !o->update)
1026                 o->skip_sparse_checkout = 1;
1027         if (!o->skip_sparse_checkout) {
1028                 if (add_excludes_from_file_to_list(git_path("info/sparse-checkout"), "", 0, &el, 0) < 0)
1029                         o->skip_sparse_checkout = 1;
1030                 else
1031                         o->el = &el;
1032         }
1033
1034         memset(&o->result, 0, sizeof(o->result));
1035         o->result.initialized = 1;
1036         o->result.timestamp.sec = o->src_index->timestamp.sec;
1037         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1038         o->result.version = o->src_index->version;
1039         o->result.split_index = o->src_index->split_index;
1040         if (o->result.split_index)
1041                 o->result.split_index->refcount++;
1042         hashcpy(o->result.sha1, o->src_index->sha1);
1043         o->merge_size = len;
1044         mark_all_ce_unused(o->src_index);
1045
1046         /*
1047          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1048          */
1049         if (!o->skip_sparse_checkout)
1050                 mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1051
1052         if (!dfc)
1053                 dfc = xcalloc(1, cache_entry_size(0));
1054         o->df_conflict_entry = dfc;
1055
1056         if (len) {
1057                 const char *prefix = o->prefix ? o->prefix : "";
1058                 struct traverse_info info;
1059
1060                 setup_traverse_info(&info, prefix);
1061                 info.fn = unpack_callback;
1062                 info.data = o;
1063                 info.show_all_errors = o->show_all_errors;
1064                 info.pathspec = o->pathspec;
1065
1066                 if (o->prefix) {
1067                         /*
1068                          * Unpack existing index entries that sort before the
1069                          * prefix the tree is spliced into.  Note that o->merge
1070                          * is always true in this case.
1071                          */
1072                         while (1) {
1073                                 struct cache_entry *ce = next_cache_entry(o);
1074                                 if (!ce)
1075                                         break;
1076                                 if (ce_in_traverse_path(ce, &info))
1077                                         break;
1078                                 if (unpack_index_entry(ce, o) < 0)
1079                                         goto return_failed;
1080                         }
1081                 }
1082
1083                 if (traverse_trees(len, t, &info) < 0)
1084                         goto return_failed;
1085         }
1086
1087         /* Any left-over entries in the index? */
1088         if (o->merge) {
1089                 while (1) {
1090                         struct cache_entry *ce = next_cache_entry(o);
1091                         if (!ce)
1092                                 break;
1093                         if (unpack_index_entry(ce, o) < 0)
1094                                 goto return_failed;
1095                 }
1096         }
1097         mark_all_ce_unused(o->src_index);
1098
1099         if (o->trivial_merges_only && o->nontrivial_merge) {
1100                 ret = unpack_failed(o, "Merge requires file-level merging");
1101                 goto done;
1102         }
1103
1104         if (!o->skip_sparse_checkout) {
1105                 int empty_worktree = 1;
1106
1107                 /*
1108                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1109                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1110                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1111                  */
1112                 mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1113
1114                 ret = 0;
1115                 for (i = 0; i < o->result.cache_nr; i++) {
1116                         struct cache_entry *ce = o->result.cache[i];
1117
1118                         /*
1119                          * Entries marked with CE_ADDED in merged_entry() do not have
1120                          * verify_absent() check (the check is effectively disabled
1121                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1122                          *
1123                          * Do the real check now because we have had
1124                          * correct CE_NEW_SKIP_WORKTREE
1125                          */
1126                         if (ce->ce_flags & CE_ADDED &&
1127                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1128                                 if (!o->show_all_errors)
1129                                         goto return_failed;
1130                                 ret = -1;
1131                         }
1132
1133                         if (apply_sparse_checkout(&o->result, ce, o)) {
1134                                 if (!o->show_all_errors)
1135                                         goto return_failed;
1136                                 ret = -1;
1137                         }
1138                         if (!ce_skip_worktree(ce))
1139                                 empty_worktree = 0;
1140
1141                 }
1142                 if (ret < 0)
1143                         goto return_failed;
1144                 /*
1145                  * Sparse checkout is meant to narrow down checkout area
1146                  * but it does not make sense to narrow down to empty working
1147                  * tree. This is usually a mistake in sparse checkout rules.
1148                  * Do not allow users to do that.
1149                  */
1150                 if (o->result.cache_nr && empty_worktree) {
1151                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1152                         goto done;
1153                 }
1154         }
1155
1156         o->src_index = NULL;
1157         ret = check_updates(o) ? (-2) : 0;
1158         if (o->dst_index) {
1159                 discard_index(o->dst_index);
1160                 *o->dst_index = o->result;
1161         } else {
1162                 discard_index(&o->result);
1163         }
1164
1165 done:
1166         clear_exclude_list(&el);
1167         return ret;
1168
1169 return_failed:
1170         if (o->show_all_errors)
1171                 display_error_msgs(o);
1172         mark_all_ce_unused(o->src_index);
1173         ret = unpack_failed(o, NULL);
1174         if (o->exiting_early)
1175                 ret = 0;
1176         goto done;
1177 }
1178
1179 /* Here come the merge functions */
1180
1181 static int reject_merge(const struct cache_entry *ce,
1182                         struct unpack_trees_options *o)
1183 {
1184         return o->gently ? -1 :
1185                 add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1186 }
1187
1188 static int same(const struct cache_entry *a, const struct cache_entry *b)
1189 {
1190         if (!!a != !!b)
1191                 return 0;
1192         if (!a && !b)
1193                 return 1;
1194         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1195                 return 0;
1196         return a->ce_mode == b->ce_mode &&
1197                !hashcmp(a->sha1, b->sha1);
1198 }
1199
1200
1201 /*
1202  * When a CE gets turned into an unmerged entry, we
1203  * want it to be up-to-date
1204  */
1205 static int verify_uptodate_1(const struct cache_entry *ce,
1206                              struct unpack_trees_options *o,
1207                              enum unpack_trees_error_types error_type)
1208 {
1209         struct stat st;
1210
1211         if (o->index_only)
1212                 return 0;
1213
1214         /*
1215          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1216          * if this entry is truly up-to-date because this file may be
1217          * overwritten.
1218          */
1219         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1220                 ; /* keep checking */
1221         else if (o->reset || ce_uptodate(ce))
1222                 return 0;
1223
1224         if (!lstat(ce->name, &st)) {
1225                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1226                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1227                 if (!changed)
1228                         return 0;
1229                 /*
1230                  * NEEDSWORK: the current default policy is to allow
1231                  * submodule to be out of sync wrt the superproject
1232                  * index.  This needs to be tightened later for
1233                  * submodules that are marked to be automatically
1234                  * checked out.
1235                  */
1236                 if (S_ISGITLINK(ce->ce_mode))
1237                         return 0;
1238                 errno = 0;
1239         }
1240         if (errno == ENOENT)
1241                 return 0;
1242         return o->gently ? -1 :
1243                 add_rejected_path(o, error_type, ce->name);
1244 }
1245
1246 static int verify_uptodate(const struct cache_entry *ce,
1247                            struct unpack_trees_options *o)
1248 {
1249         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1250                 return 0;
1251         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1252 }
1253
1254 static int verify_uptodate_sparse(const struct cache_entry *ce,
1255                                   struct unpack_trees_options *o)
1256 {
1257         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1258 }
1259
1260 static void invalidate_ce_path(const struct cache_entry *ce,
1261                                struct unpack_trees_options *o)
1262 {
1263         if (!ce)
1264                 return;
1265         cache_tree_invalidate_path(o->src_index, ce->name);
1266         untracked_cache_invalidate_path(o->src_index, ce->name);
1267 }
1268
1269 /*
1270  * Check that checking out ce->sha1 in subdir ce->name is not
1271  * going to overwrite any working files.
1272  *
1273  * Currently, git does not checkout subprojects during a superproject
1274  * checkout, so it is not going to overwrite anything.
1275  */
1276 static int verify_clean_submodule(const struct cache_entry *ce,
1277                                   enum unpack_trees_error_types error_type,
1278                                   struct unpack_trees_options *o)
1279 {
1280         return 0;
1281 }
1282
1283 static int verify_clean_subdirectory(const struct cache_entry *ce,
1284                                      enum unpack_trees_error_types error_type,
1285                                      struct unpack_trees_options *o)
1286 {
1287         /*
1288          * we are about to extract "ce->name"; we would not want to lose
1289          * anything in the existing directory there.
1290          */
1291         int namelen;
1292         int i;
1293         struct dir_struct d;
1294         char *pathbuf;
1295         int cnt = 0;
1296         unsigned char sha1[20];
1297
1298         if (S_ISGITLINK(ce->ce_mode) &&
1299             resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
1300                 /* If we are not going to update the submodule, then
1301                  * we don't care.
1302                  */
1303                 if (!hashcmp(sha1, ce->sha1))
1304                         return 0;
1305                 return verify_clean_submodule(ce, error_type, o);
1306         }
1307
1308         /*
1309          * First let's make sure we do not have a local modification
1310          * in that directory.
1311          */
1312         namelen = ce_namelen(ce);
1313         for (i = locate_in_src_index(ce, o);
1314              i < o->src_index->cache_nr;
1315              i++) {
1316                 struct cache_entry *ce2 = o->src_index->cache[i];
1317                 int len = ce_namelen(ce2);
1318                 if (len < namelen ||
1319                     strncmp(ce->name, ce2->name, namelen) ||
1320                     ce2->name[namelen] != '/')
1321                         break;
1322                 /*
1323                  * ce2->name is an entry in the subdirectory to be
1324                  * removed.
1325                  */
1326                 if (!ce_stage(ce2)) {
1327                         if (verify_uptodate(ce2, o))
1328                                 return -1;
1329                         add_entry(o, ce2, CE_REMOVE, 0);
1330                         mark_ce_used(ce2, o);
1331                 }
1332                 cnt++;
1333         }
1334
1335         /*
1336          * Then we need to make sure that we do not lose a locally
1337          * present file that is not ignored.
1338          */
1339         pathbuf = xmalloc(namelen + 2);
1340         memcpy(pathbuf, ce->name, namelen);
1341         strcpy(pathbuf+namelen, "/");
1342
1343         memset(&d, 0, sizeof(d));
1344         if (o->dir)
1345                 d.exclude_per_dir = o->dir->exclude_per_dir;
1346         i = read_directory(&d, pathbuf, namelen+1, NULL);
1347         if (i)
1348                 return o->gently ? -1 :
1349                         add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1350         free(pathbuf);
1351         return cnt;
1352 }
1353
1354 /*
1355  * This gets called when there was no index entry for the tree entry 'dst',
1356  * but we found a file in the working tree that 'lstat()' said was fine,
1357  * and we're on a case-insensitive filesystem.
1358  *
1359  * See if we can find a case-insensitive match in the index that also
1360  * matches the stat information, and assume it's that other file!
1361  */
1362 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1363 {
1364         const struct cache_entry *src;
1365
1366         src = index_file_exists(o->src_index, name, len, 1);
1367         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1368 }
1369
1370 static int check_ok_to_remove(const char *name, int len, int dtype,
1371                               const struct cache_entry *ce, struct stat *st,
1372                               enum unpack_trees_error_types error_type,
1373                               struct unpack_trees_options *o)
1374 {
1375         const struct cache_entry *result;
1376
1377         /*
1378          * It may be that the 'lstat()' succeeded even though
1379          * target 'ce' was absent, because there is an old
1380          * entry that is different only in case..
1381          *
1382          * Ignore that lstat() if it matches.
1383          */
1384         if (ignore_case && icase_exists(o, name, len, st))
1385                 return 0;
1386
1387         if (o->dir &&
1388             is_excluded(o->dir, name, &dtype))
1389                 /*
1390                  * ce->name is explicitly excluded, so it is Ok to
1391                  * overwrite it.
1392                  */
1393                 return 0;
1394         if (S_ISDIR(st->st_mode)) {
1395                 /*
1396                  * We are checking out path "foo" and
1397                  * found "foo/." in the working tree.
1398                  * This is tricky -- if we have modified
1399                  * files that are in "foo/" we would lose
1400                  * them.
1401                  */
1402                 if (verify_clean_subdirectory(ce, error_type, o) < 0)
1403                         return -1;
1404                 return 0;
1405         }
1406
1407         /*
1408          * The previous round may already have decided to
1409          * delete this path, which is in a subdirectory that
1410          * is being replaced with a blob.
1411          */
1412         result = index_file_exists(&o->result, name, len, 0);
1413         if (result) {
1414                 if (result->ce_flags & CE_REMOVE)
1415                         return 0;
1416         }
1417
1418         return o->gently ? -1 :
1419                 add_rejected_path(o, error_type, name);
1420 }
1421
1422 /*
1423  * We do not want to remove or overwrite a working tree file that
1424  * is not tracked, unless it is ignored.
1425  */
1426 static int verify_absent_1(const struct cache_entry *ce,
1427                            enum unpack_trees_error_types error_type,
1428                            struct unpack_trees_options *o)
1429 {
1430         int len;
1431         struct stat st;
1432
1433         if (o->index_only || o->reset || !o->update)
1434                 return 0;
1435
1436         len = check_leading_path(ce->name, ce_namelen(ce));
1437         if (!len)
1438                 return 0;
1439         else if (len > 0) {
1440                 char path[PATH_MAX + 1];
1441                 memcpy(path, ce->name, len);
1442                 path[len] = 0;
1443                 if (lstat(path, &st))
1444                         return error("cannot stat '%s': %s", path,
1445                                         strerror(errno));
1446
1447                 return check_ok_to_remove(path, len, DT_UNKNOWN, NULL, &st,
1448                                 error_type, o);
1449         } else if (lstat(ce->name, &st)) {
1450                 if (errno != ENOENT)
1451                         return error("cannot stat '%s': %s", ce->name,
1452                                      strerror(errno));
1453                 return 0;
1454         } else {
1455                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1456                                           ce_to_dtype(ce), ce, &st,
1457                                           error_type, o);
1458         }
1459 }
1460
1461 static int verify_absent(const struct cache_entry *ce,
1462                          enum unpack_trees_error_types error_type,
1463                          struct unpack_trees_options *o)
1464 {
1465         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1466                 return 0;
1467         return verify_absent_1(ce, error_type, o);
1468 }
1469
1470 static int verify_absent_sparse(const struct cache_entry *ce,
1471                                 enum unpack_trees_error_types error_type,
1472                                 struct unpack_trees_options *o)
1473 {
1474         enum unpack_trees_error_types orphaned_error = error_type;
1475         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1476                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1477
1478         return verify_absent_1(ce, orphaned_error, o);
1479 }
1480
1481 static int merged_entry(const struct cache_entry *ce,
1482                         const struct cache_entry *old,
1483                         struct unpack_trees_options *o)
1484 {
1485         int update = CE_UPDATE;
1486         struct cache_entry *merge = dup_entry(ce);
1487
1488         if (!old) {
1489                 /*
1490                  * New index entries. In sparse checkout, the following
1491                  * verify_absent() will be delayed until after
1492                  * traverse_trees() finishes in unpack_trees(), then:
1493                  *
1494                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1495                  *  - verify_absent() be called again, this time with
1496                  *    correct CE_NEW_SKIP_WORKTREE
1497                  *
1498                  * verify_absent() call here does nothing in sparse
1499                  * checkout (i.e. o->skip_sparse_checkout == 0)
1500                  */
1501                 update |= CE_ADDED;
1502                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1503
1504                 if (verify_absent(merge,
1505                                   ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1506                         free(merge);
1507                         return -1;
1508                 }
1509                 invalidate_ce_path(merge, o);
1510         } else if (!(old->ce_flags & CE_CONFLICTED)) {
1511                 /*
1512                  * See if we can re-use the old CE directly?
1513                  * That way we get the uptodate stat info.
1514                  *
1515                  * This also removes the UPDATE flag on a match; otherwise
1516                  * we will end up overwriting local changes in the work tree.
1517                  */
1518                 if (same(old, merge)) {
1519                         copy_cache_entry(merge, old);
1520                         update = 0;
1521                 } else {
1522                         if (verify_uptodate(old, o)) {
1523                                 free(merge);
1524                                 return -1;
1525                         }
1526                         /* Migrate old flags over */
1527                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1528                         invalidate_ce_path(old, o);
1529                 }
1530         } else {
1531                 /*
1532                  * Previously unmerged entry left as an existence
1533                  * marker by read_index_unmerged();
1534                  */
1535                 invalidate_ce_path(old, o);
1536         }
1537
1538         do_add_entry(o, merge, update, CE_STAGEMASK);
1539         return 1;
1540 }
1541
1542 static int deleted_entry(const struct cache_entry *ce,
1543                          const struct cache_entry *old,
1544                          struct unpack_trees_options *o)
1545 {
1546         /* Did it exist in the index? */
1547         if (!old) {
1548                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1549                         return -1;
1550                 return 0;
1551         }
1552         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1553                 return -1;
1554         add_entry(o, ce, CE_REMOVE, 0);
1555         invalidate_ce_path(ce, o);
1556         return 1;
1557 }
1558
1559 static int keep_entry(const struct cache_entry *ce,
1560                       struct unpack_trees_options *o)
1561 {
1562         add_entry(o, ce, 0, 0);
1563         return 1;
1564 }
1565
1566 #if DBRT_DEBUG
1567 static void show_stage_entry(FILE *o,
1568                              const char *label, const struct cache_entry *ce)
1569 {
1570         if (!ce)
1571                 fprintf(o, "%s (missing)\n", label);
1572         else
1573                 fprintf(o, "%s%06o %s %d\t%s\n",
1574                         label,
1575                         ce->ce_mode,
1576                         sha1_to_hex(ce->sha1),
1577                         ce_stage(ce),
1578                         ce->name);
1579 }
1580 #endif
1581
1582 int threeway_merge(const struct cache_entry * const *stages,
1583                    struct unpack_trees_options *o)
1584 {
1585         const struct cache_entry *index;
1586         const struct cache_entry *head;
1587         const struct cache_entry *remote = stages[o->head_idx + 1];
1588         int count;
1589         int head_match = 0;
1590         int remote_match = 0;
1591
1592         int df_conflict_head = 0;
1593         int df_conflict_remote = 0;
1594
1595         int any_anc_missing = 0;
1596         int no_anc_exists = 1;
1597         int i;
1598
1599         for (i = 1; i < o->head_idx; i++) {
1600                 if (!stages[i] || stages[i] == o->df_conflict_entry)
1601                         any_anc_missing = 1;
1602                 else
1603                         no_anc_exists = 0;
1604         }
1605
1606         index = stages[0];
1607         head = stages[o->head_idx];
1608
1609         if (head == o->df_conflict_entry) {
1610                 df_conflict_head = 1;
1611                 head = NULL;
1612         }
1613
1614         if (remote == o->df_conflict_entry) {
1615                 df_conflict_remote = 1;
1616                 remote = NULL;
1617         }
1618
1619         /*
1620          * First, if there's a #16 situation, note that to prevent #13
1621          * and #14.
1622          */
1623         if (!same(remote, head)) {
1624                 for (i = 1; i < o->head_idx; i++) {
1625                         if (same(stages[i], head)) {
1626                                 head_match = i;
1627                         }
1628                         if (same(stages[i], remote)) {
1629                                 remote_match = i;
1630                         }
1631                 }
1632         }
1633
1634         /*
1635          * We start with cases where the index is allowed to match
1636          * something other than the head: #14(ALT) and #2ALT, where it
1637          * is permitted to match the result instead.
1638          */
1639         /* #14, #14ALT, #2ALT */
1640         if (remote && !df_conflict_head && head_match && !remote_match) {
1641                 if (index && !same(index, remote) && !same(index, head))
1642                         return reject_merge(index, o);
1643                 return merged_entry(remote, index, o);
1644         }
1645         /*
1646          * If we have an entry in the index cache, then we want to
1647          * make sure that it matches head.
1648          */
1649         if (index && !same(index, head))
1650                 return reject_merge(index, o);
1651
1652         if (head) {
1653                 /* #5ALT, #15 */
1654                 if (same(head, remote))
1655                         return merged_entry(head, index, o);
1656                 /* #13, #3ALT */
1657                 if (!df_conflict_remote && remote_match && !head_match)
1658                         return merged_entry(head, index, o);
1659         }
1660
1661         /* #1 */
1662         if (!head && !remote && any_anc_missing)
1663                 return 0;
1664
1665         /*
1666          * Under the "aggressive" rule, we resolve mostly trivial
1667          * cases that we historically had git-merge-one-file resolve.
1668          */
1669         if (o->aggressive) {
1670                 int head_deleted = !head;
1671                 int remote_deleted = !remote;
1672                 const struct cache_entry *ce = NULL;
1673
1674                 if (index)
1675                         ce = index;
1676                 else if (head)
1677                         ce = head;
1678                 else if (remote)
1679                         ce = remote;
1680                 else {
1681                         for (i = 1; i < o->head_idx; i++) {
1682                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
1683                                         ce = stages[i];
1684                                         break;
1685                                 }
1686                         }
1687                 }
1688
1689                 /*
1690                  * Deleted in both.
1691                  * Deleted in one and unchanged in the other.
1692                  */
1693                 if ((head_deleted && remote_deleted) ||
1694                     (head_deleted && remote && remote_match) ||
1695                     (remote_deleted && head && head_match)) {
1696                         if (index)
1697                                 return deleted_entry(index, index, o);
1698                         if (ce && !head_deleted) {
1699                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1700                                         return -1;
1701                         }
1702                         return 0;
1703                 }
1704                 /*
1705                  * Added in both, identically.
1706                  */
1707                 if (no_anc_exists && head && remote && same(head, remote))
1708                         return merged_entry(head, index, o);
1709
1710         }
1711
1712         /* Below are "no merge" cases, which require that the index be
1713          * up-to-date to avoid the files getting overwritten with
1714          * conflict resolution files.
1715          */
1716         if (index) {
1717                 if (verify_uptodate(index, o))
1718                         return -1;
1719         }
1720
1721         o->nontrivial_merge = 1;
1722
1723         /* #2, #3, #4, #6, #7, #9, #10, #11. */
1724         count = 0;
1725         if (!head_match || !remote_match) {
1726                 for (i = 1; i < o->head_idx; i++) {
1727                         if (stages[i] && stages[i] != o->df_conflict_entry) {
1728                                 keep_entry(stages[i], o);
1729                                 count++;
1730                                 break;
1731                         }
1732                 }
1733         }
1734 #if DBRT_DEBUG
1735         else {
1736                 fprintf(stderr, "read-tree: warning #16 detected\n");
1737                 show_stage_entry(stderr, "head   ", stages[head_match]);
1738                 show_stage_entry(stderr, "remote ", stages[remote_match]);
1739         }
1740 #endif
1741         if (head) { count += keep_entry(head, o); }
1742         if (remote) { count += keep_entry(remote, o); }
1743         return count;
1744 }
1745
1746 /*
1747  * Two-way merge.
1748  *
1749  * The rule is to "carry forward" what is in the index without losing
1750  * information across a "fast-forward", favoring a successful merge
1751  * over a merge failure when it makes sense.  For details of the
1752  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
1753  *
1754  */
1755 int twoway_merge(const struct cache_entry * const *src,
1756                  struct unpack_trees_options *o)
1757 {
1758         const struct cache_entry *current = src[0];
1759         const struct cache_entry *oldtree = src[1];
1760         const struct cache_entry *newtree = src[2];
1761
1762         if (o->merge_size != 2)
1763                 return error("Cannot do a twoway merge of %d trees",
1764                              o->merge_size);
1765
1766         if (oldtree == o->df_conflict_entry)
1767                 oldtree = NULL;
1768         if (newtree == o->df_conflict_entry)
1769                 newtree = NULL;
1770
1771         if (current) {
1772                 if (current->ce_flags & CE_CONFLICTED) {
1773                         if (same(oldtree, newtree) || o->reset) {
1774                                 if (!newtree)
1775                                         return deleted_entry(current, current, o);
1776                                 else
1777                                         return merged_entry(newtree, current, o);
1778                         }
1779                         return reject_merge(current, o);
1780                 } else if ((!oldtree && !newtree) || /* 4 and 5 */
1781                          (!oldtree && newtree &&
1782                           same(current, newtree)) || /* 6 and 7 */
1783                          (oldtree && newtree &&
1784                           same(oldtree, newtree)) || /* 14 and 15 */
1785                          (oldtree && newtree &&
1786                           !same(oldtree, newtree) && /* 18 and 19 */
1787                           same(current, newtree))) {
1788                         return keep_entry(current, o);
1789                 } else if (oldtree && !newtree && same(current, oldtree)) {
1790                         /* 10 or 11 */
1791                         return deleted_entry(oldtree, current, o);
1792                 } else if (oldtree && newtree &&
1793                          same(current, oldtree) && !same(current, newtree)) {
1794                         /* 20 or 21 */
1795                         return merged_entry(newtree, current, o);
1796                 } else
1797                         return reject_merge(current, o);
1798         }
1799         else if (newtree) {
1800                 if (oldtree && !o->initial_checkout) {
1801                         /*
1802                          * deletion of the path was staged;
1803                          */
1804                         if (same(oldtree, newtree))
1805                                 return 1;
1806                         return reject_merge(oldtree, o);
1807                 }
1808                 return merged_entry(newtree, current, o);
1809         }
1810         return deleted_entry(oldtree, current, o);
1811 }
1812
1813 /*
1814  * Bind merge.
1815  *
1816  * Keep the index entries at stage0, collapse stage1 but make sure
1817  * stage0 does not have anything there.
1818  */
1819 int bind_merge(const struct cache_entry * const *src,
1820                struct unpack_trees_options *o)
1821 {
1822         const struct cache_entry *old = src[0];
1823         const struct cache_entry *a = src[1];
1824
1825         if (o->merge_size != 1)
1826                 return error("Cannot do a bind merge of %d trees",
1827                              o->merge_size);
1828         if (a && old)
1829                 return o->gently ? -1 :
1830                         error(ERRORMSG(o, ERROR_BIND_OVERLAP), a->name, old->name);
1831         if (!a)
1832                 return keep_entry(old, o);
1833         else
1834                 return merged_entry(a, NULL, o);
1835 }
1836
1837 /*
1838  * One-way merge.
1839  *
1840  * The rule is:
1841  * - take the stat information from stage0, take the data from stage1
1842  */
1843 int oneway_merge(const struct cache_entry * const *src,
1844                  struct unpack_trees_options *o)
1845 {
1846         const struct cache_entry *old = src[0];
1847         const struct cache_entry *a = src[1];
1848
1849         if (o->merge_size != 1)
1850                 return error("Cannot do a oneway merge of %d trees",
1851                              o->merge_size);
1852
1853         if (!a || a == o->df_conflict_entry)
1854                 return deleted_entry(old, old, o);
1855
1856         if (old && same(old, a)) {
1857                 int update = 0;
1858                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
1859                         struct stat st;
1860                         if (lstat(old->name, &st) ||
1861                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
1862                                 update |= CE_UPDATE;
1863                 }
1864                 add_entry(o, old, update, 0);
1865                 return 0;
1866         }
1867         return merged_entry(a, old, o);
1868 }