Merge branch 'pg/maint-1.7.9-am-where-is-patch' into maint
[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
12 /*
13  * Error messages expected by scripts out of plumbing commands such as
14  * read-tree.  Non-scripted Porcelain is not required to use these messages
15  * and in fact are encouraged to reword them to better suit their particular
16  * situation better.  See how "git checkout" and "git merge" replaces
17  * them using setup_unpack_trees_porcelain(), for example.
18  */
19 static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
20         /* ERROR_WOULD_OVERWRITE */
21         "Entry '%s' would be overwritten by merge. Cannot merge.",
22
23         /* ERROR_NOT_UPTODATE_FILE */
24         "Entry '%s' not uptodate. Cannot merge.",
25
26         /* ERROR_NOT_UPTODATE_DIR */
27         "Updating '%s' would lose untracked files in it",
28
29         /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
30         "Untracked working tree file '%s' would be overwritten by merge.",
31
32         /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
33         "Untracked working tree file '%s' would be removed by merge.",
34
35         /* ERROR_BIND_OVERLAP */
36         "Entry '%s' overlaps with '%s'.  Cannot bind.",
37
38         /* ERROR_SPARSE_NOT_UPTODATE_FILE */
39         "Entry '%s' not uptodate. Cannot update sparse checkout.",
40
41         /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
42         "Working tree file '%s' would be overwritten by sparse checkout update.",
43
44         /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
45         "Working tree file '%s' would be removed by sparse checkout update.",
46 };
47
48 #define ERRORMSG(o,type) \
49         ( ((o) && (o)->msgs[(type)]) \
50           ? ((o)->msgs[(type)])      \
51           : (unpack_plumbing_errors[(type)]) )
52
53 void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
54                                   const char *cmd)
55 {
56         int i;
57         const char **msgs = opts->msgs;
58         const char *msg;
59         char *tmp;
60         const char *cmd2 = strcmp(cmd, "checkout") ? cmd : "switch branches";
61         if (advice_commit_before_merge)
62                 msg = "Your local changes to the following files would be overwritten by %s:\n%%s"
63                         "Please, commit your changes or stash them before you can %s.";
64         else
65                 msg = "Your local changes to the following files would be overwritten by %s:\n%%s";
66         tmp = xmalloc(strlen(msg) + strlen(cmd) + strlen(cmd2) - 2);
67         sprintf(tmp, msg, cmd, cmd2);
68         msgs[ERROR_WOULD_OVERWRITE] = tmp;
69         msgs[ERROR_NOT_UPTODATE_FILE] = tmp;
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         tmp = xmalloc(strlen(msg) + strlen(cmd) + strlen("removed") + strlen(cmd2) - 4);
80         sprintf(tmp, msg, "removed", cmd, cmd2);
81         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = tmp;
82         tmp = xmalloc(strlen(msg) + strlen(cmd) + strlen("overwritten") + strlen(cmd2) - 4);
83         sprintf(tmp, msg, "overwritten", cmd, cmd2);
84         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = tmp;
85
86         /*
87          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
88          * cannot easily display it as a list.
89          */
90         msgs[ERROR_BIND_OVERLAP] = "Entry '%s' overlaps with '%s'.  Cannot bind.";
91
92         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
93                 "Cannot update sparse checkout: the following entries are not up-to-date:\n%s";
94         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
95                 "The following Working tree files would be overwritten by sparse checkout update:\n%s";
96         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
97                 "The following Working tree files would be removed by sparse checkout update:\n%s";
98
99         opts->show_all_errors = 1;
100         /* rejected paths may not have a static buffer */
101         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
102                 opts->unpack_rejects[i].strdup_strings = 1;
103 }
104
105 static void do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
106                          unsigned int set, unsigned int clear)
107 {
108         clear |= CE_HASHED | CE_UNHASHED;
109
110         if (set & CE_REMOVE)
111                 set |= CE_WT_REMOVE;
112
113         ce->next = NULL;
114         ce->ce_flags = (ce->ce_flags & ~clear) | set;
115         add_index_entry(&o->result, ce,
116                         ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
117 }
118
119 static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
120         unsigned int set, unsigned int clear)
121 {
122         unsigned int size = ce_size(ce);
123         struct cache_entry *new = xmalloc(size);
124
125         memcpy(new, ce, size);
126         do_add_entry(o, new, set, clear);
127 }
128
129 /*
130  * add error messages on path <path>
131  * corresponding to the type <e> with the message <msg>
132  * indicating if it should be display in porcelain or not
133  */
134 static int add_rejected_path(struct unpack_trees_options *o,
135                              enum unpack_trees_error_types e,
136                              const char *path)
137 {
138         if (!o->show_all_errors)
139                 return error(ERRORMSG(o, e), path);
140
141         /*
142          * Otherwise, insert in a list for future display by
143          * display_error_msgs()
144          */
145         string_list_append(&o->unpack_rejects[e], path);
146         return -1;
147 }
148
149 /*
150  * display all the error messages stored in a nice way
151  */
152 static void display_error_msgs(struct unpack_trees_options *o)
153 {
154         int e, i;
155         int something_displayed = 0;
156         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
157                 struct string_list *rejects = &o->unpack_rejects[e];
158                 if (rejects->nr > 0) {
159                         struct strbuf path = STRBUF_INIT;
160                         something_displayed = 1;
161                         for (i = 0; i < rejects->nr; i++)
162                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
163                         error(ERRORMSG(o, e), path.buf);
164                         strbuf_release(&path);
165                 }
166                 string_list_clear(rejects, 0);
167         }
168         if (something_displayed)
169                 fprintf(stderr, "Aborting\n");
170 }
171
172 /*
173  * Unlink the last component and schedule the leading directories for
174  * removal, such that empty directories get removed.
175  */
176 static void unlink_entry(struct cache_entry *ce)
177 {
178         if (!check_leading_path(ce->name, ce_namelen(ce)))
179                 return;
180         if (remove_or_warn(ce->ce_mode, ce->name))
181                 return;
182         schedule_dir_for_removal(ce->name, ce_namelen(ce));
183 }
184
185 static struct checkout state;
186 static int check_updates(struct unpack_trees_options *o)
187 {
188         unsigned cnt = 0, total = 0;
189         struct progress *progress = NULL;
190         struct index_state *index = &o->result;
191         int i;
192         int errs = 0;
193
194         if (o->update && o->verbose_update) {
195                 for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
196                         struct cache_entry *ce = index->cache[cnt];
197                         if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
198                                 total++;
199                 }
200
201                 progress = start_progress_delay("Checking out files",
202                                                 total, 50, 1);
203                 cnt = 0;
204         }
205
206         if (o->update)
207                 git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
208         for (i = 0; i < index->cache_nr; i++) {
209                 struct cache_entry *ce = index->cache[i];
210
211                 if (ce->ce_flags & CE_WT_REMOVE) {
212                         display_progress(progress, ++cnt);
213                         if (o->update && !o->dry_run)
214                                 unlink_entry(ce);
215                         continue;
216                 }
217         }
218         remove_marked_cache_entries(&o->result);
219         remove_scheduled_dirs();
220
221         for (i = 0; i < index->cache_nr; i++) {
222                 struct cache_entry *ce = index->cache[i];
223
224                 if (ce->ce_flags & CE_UPDATE) {
225                         display_progress(progress, ++cnt);
226                         ce->ce_flags &= ~CE_UPDATE;
227                         if (o->update && !o->dry_run) {
228                                 errs |= checkout_entry(ce, &state, NULL);
229                         }
230                 }
231         }
232         stop_progress(&progress);
233         if (o->update)
234                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
235         return errs != 0;
236 }
237
238 static int verify_uptodate_sparse(struct cache_entry *ce, struct unpack_trees_options *o);
239 static int verify_absent_sparse(struct cache_entry *ce, enum unpack_trees_error_types, struct unpack_trees_options *o);
240
241 static int apply_sparse_checkout(struct cache_entry *ce, struct unpack_trees_options *o)
242 {
243         int was_skip_worktree = ce_skip_worktree(ce);
244
245         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
246                 ce->ce_flags |= CE_SKIP_WORKTREE;
247         else
248                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
249
250         /*
251          * if (!was_skip_worktree && !ce_skip_worktree()) {
252          *      This is perfectly normal. Move on;
253          * }
254          */
255
256         /*
257          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
258          * area as a result of ce_skip_worktree() shortcuts in
259          * verify_absent() and verify_uptodate().
260          * Make sure they don't modify worktree if they are already
261          * outside checkout area
262          */
263         if (was_skip_worktree && ce_skip_worktree(ce)) {
264                 ce->ce_flags &= ~CE_UPDATE;
265
266                 /*
267                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
268                  * on to get that file removed from both index and worktree.
269                  * If that file is already outside worktree area, don't
270                  * bother remove it.
271                  */
272                 if (ce->ce_flags & CE_REMOVE)
273                         ce->ce_flags &= ~CE_WT_REMOVE;
274         }
275
276         if (!was_skip_worktree && ce_skip_worktree(ce)) {
277                 /*
278                  * If CE_UPDATE is set, verify_uptodate() must be called already
279                  * also stat info may have lost after merged_entry() so calling
280                  * verify_uptodate() again may fail
281                  */
282                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
283                         return -1;
284                 ce->ce_flags |= CE_WT_REMOVE;
285         }
286         if (was_skip_worktree && !ce_skip_worktree(ce)) {
287                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
288                         return -1;
289                 ce->ce_flags |= CE_UPDATE;
290         }
291         return 0;
292 }
293
294 static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
295 {
296         int ret = o->fn(src, o);
297         if (ret > 0)
298                 ret = 0;
299         return ret;
300 }
301
302 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
303 {
304         ce->ce_flags |= CE_UNPACKED;
305
306         if (o->cache_bottom < o->src_index->cache_nr &&
307             o->src_index->cache[o->cache_bottom] == ce) {
308                 int bottom = o->cache_bottom;
309                 while (bottom < o->src_index->cache_nr &&
310                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
311                         bottom++;
312                 o->cache_bottom = bottom;
313         }
314 }
315
316 static void mark_all_ce_unused(struct index_state *index)
317 {
318         int i;
319         for (i = 0; i < index->cache_nr; i++)
320                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
321 }
322
323 static int locate_in_src_index(struct cache_entry *ce,
324                                struct unpack_trees_options *o)
325 {
326         struct index_state *index = o->src_index;
327         int len = ce_namelen(ce);
328         int pos = index_name_pos(index, ce->name, len);
329         if (pos < 0)
330                 pos = -1 - pos;
331         return pos;
332 }
333
334 /*
335  * We call unpack_index_entry() with an unmerged cache entry
336  * only in diff-index, and it wants a single callback.  Skip
337  * the other unmerged entry with the same name.
338  */
339 static void mark_ce_used_same_name(struct cache_entry *ce,
340                                    struct unpack_trees_options *o)
341 {
342         struct index_state *index = o->src_index;
343         int len = ce_namelen(ce);
344         int pos;
345
346         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
347                 struct cache_entry *next = index->cache[pos];
348                 if (len != ce_namelen(next) ||
349                     memcmp(ce->name, next->name, len))
350                         break;
351                 mark_ce_used(next, o);
352         }
353 }
354
355 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
356 {
357         const struct index_state *index = o->src_index;
358         int pos = o->cache_bottom;
359
360         while (pos < index->cache_nr) {
361                 struct cache_entry *ce = index->cache[pos];
362                 if (!(ce->ce_flags & CE_UNPACKED))
363                         return ce;
364                 pos++;
365         }
366         return NULL;
367 }
368
369 static void add_same_unmerged(struct cache_entry *ce,
370                               struct unpack_trees_options *o)
371 {
372         struct index_state *index = o->src_index;
373         int len = ce_namelen(ce);
374         int pos = index_name_pos(index, ce->name, len);
375
376         if (0 <= pos)
377                 die("programming error in a caller of mark_ce_used_same_name");
378         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
379                 struct cache_entry *next = index->cache[pos];
380                 if (len != ce_namelen(next) ||
381                     memcmp(ce->name, next->name, len))
382                         break;
383                 add_entry(o, next, 0, 0);
384                 mark_ce_used(next, o);
385         }
386 }
387
388 static int unpack_index_entry(struct cache_entry *ce,
389                               struct unpack_trees_options *o)
390 {
391         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
392         int ret;
393
394         src[0] = ce;
395
396         mark_ce_used(ce, o);
397         if (ce_stage(ce)) {
398                 if (o->skip_unmerged) {
399                         add_entry(o, ce, 0, 0);
400                         return 0;
401                 }
402         }
403         ret = call_unpack_fn(src, o);
404         if (ce_stage(ce))
405                 mark_ce_used_same_name(ce, o);
406         return ret;
407 }
408
409 static int find_cache_pos(struct traverse_info *, const struct name_entry *);
410
411 static void restore_cache_bottom(struct traverse_info *info, int bottom)
412 {
413         struct unpack_trees_options *o = info->data;
414
415         if (o->diff_index_cached)
416                 return;
417         o->cache_bottom = bottom;
418 }
419
420 static int switch_cache_bottom(struct traverse_info *info)
421 {
422         struct unpack_trees_options *o = info->data;
423         int ret, pos;
424
425         if (o->diff_index_cached)
426                 return 0;
427         ret = o->cache_bottom;
428         pos = find_cache_pos(info->prev, &info->name);
429
430         if (pos < -1)
431                 o->cache_bottom = -2 - pos;
432         else if (pos < 0)
433                 o->cache_bottom = o->src_index->cache_nr;
434         return ret;
435 }
436
437 static int traverse_trees_recursive(int n, unsigned long dirmask,
438                                     unsigned long df_conflicts,
439                                     struct name_entry *names,
440                                     struct traverse_info *info)
441 {
442         int i, ret, bottom;
443         struct tree_desc t[MAX_UNPACK_TREES];
444         void *buf[MAX_UNPACK_TREES];
445         struct traverse_info newinfo;
446         struct name_entry *p;
447
448         p = names;
449         while (!p->mode)
450                 p++;
451
452         newinfo = *info;
453         newinfo.prev = info;
454         newinfo.pathspec = info->pathspec;
455         newinfo.name = *p;
456         newinfo.pathlen += tree_entry_len(p) + 1;
457         newinfo.conflicts |= df_conflicts;
458
459         for (i = 0; i < n; i++, dirmask >>= 1) {
460                 const unsigned char *sha1 = NULL;
461                 if (dirmask & 1)
462                         sha1 = names[i].sha1;
463                 buf[i] = fill_tree_descriptor(t+i, sha1);
464         }
465
466         bottom = switch_cache_bottom(&newinfo);
467         ret = traverse_trees(n, t, &newinfo);
468         restore_cache_bottom(&newinfo, bottom);
469
470         for (i = 0; i < n; i++)
471                 free(buf[i]);
472
473         return ret;
474 }
475
476 /*
477  * Compare the traverse-path to the cache entry without actually
478  * having to generate the textual representation of the traverse
479  * path.
480  *
481  * NOTE! This *only* compares up to the size of the traverse path
482  * itself - the caller needs to do the final check for the cache
483  * entry having more data at the end!
484  */
485 static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
486 {
487         int len, pathlen, ce_len;
488         const char *ce_name;
489
490         if (info->prev) {
491                 int cmp = do_compare_entry(ce, info->prev, &info->name);
492                 if (cmp)
493                         return cmp;
494         }
495         pathlen = info->pathlen;
496         ce_len = ce_namelen(ce);
497
498         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
499         if (ce_len < pathlen)
500                 return -1;
501
502         ce_len -= pathlen;
503         ce_name = ce->name + pathlen;
504
505         len = tree_entry_len(n);
506         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
507 }
508
509 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
510 {
511         int cmp = do_compare_entry(ce, info, n);
512         if (cmp)
513                 return cmp;
514
515         /*
516          * Even if the beginning compared identically, the ce should
517          * compare as bigger than a directory leading up to it!
518          */
519         return ce_namelen(ce) > traverse_path_len(info, n);
520 }
521
522 static int ce_in_traverse_path(const struct cache_entry *ce,
523                                const struct traverse_info *info)
524 {
525         if (!info->prev)
526                 return 1;
527         if (do_compare_entry(ce, info->prev, &info->name))
528                 return 0;
529         /*
530          * If ce (blob) is the same name as the path (which is a tree
531          * we will be descending into), it won't be inside it.
532          */
533         return (info->pathlen < ce_namelen(ce));
534 }
535
536 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
537 {
538         int len = traverse_path_len(info, n);
539         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
540
541         ce->ce_mode = create_ce_mode(n->mode);
542         ce->ce_flags = create_ce_flags(len, stage);
543         hashcpy(ce->sha1, n->sha1);
544         make_traverse_path(ce->name, info, n);
545
546         return ce;
547 }
548
549 static int unpack_nondirectories(int n, unsigned long mask,
550                                  unsigned long dirmask,
551                                  struct cache_entry **src,
552                                  const struct name_entry *names,
553                                  const struct traverse_info *info)
554 {
555         int i;
556         struct unpack_trees_options *o = info->data;
557         unsigned long conflicts;
558
559         /* Do we have *only* directories? Nothing to do */
560         if (mask == dirmask && !src[0])
561                 return 0;
562
563         conflicts = info->conflicts;
564         if (o->merge)
565                 conflicts >>= 1;
566         conflicts |= dirmask;
567
568         /*
569          * Ok, we've filled in up to any potential index entry in src[0],
570          * now do the rest.
571          */
572         for (i = 0; i < n; i++) {
573                 int stage;
574                 unsigned int bit = 1ul << i;
575                 if (conflicts & bit) {
576                         src[i + o->merge] = o->df_conflict_entry;
577                         continue;
578                 }
579                 if (!(mask & bit))
580                         continue;
581                 if (!o->merge)
582                         stage = 0;
583                 else if (i + 1 < o->head_idx)
584                         stage = 1;
585                 else if (i + 1 > o->head_idx)
586                         stage = 3;
587                 else
588                         stage = 2;
589                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
590         }
591
592         if (o->merge)
593                 return call_unpack_fn(src, o);
594
595         for (i = 0; i < n; i++)
596                 if (src[i] && src[i] != o->df_conflict_entry)
597                         do_add_entry(o, src[i], 0, 0);
598         return 0;
599 }
600
601 static int unpack_failed(struct unpack_trees_options *o, const char *message)
602 {
603         discard_index(&o->result);
604         if (!o->gently && !o->exiting_early) {
605                 if (message)
606                         return error("%s", message);
607                 return -1;
608         }
609         return -1;
610 }
611
612 /* NEEDSWORK: give this a better name and share with tree-walk.c */
613 static int name_compare(const char *a, int a_len,
614                         const char *b, int b_len)
615 {
616         int len = (a_len < b_len) ? a_len : b_len;
617         int cmp = memcmp(a, b, len);
618         if (cmp)
619                 return cmp;
620         return (a_len - b_len);
621 }
622
623 /*
624  * The tree traversal is looking at name p.  If we have a matching entry,
625  * return it.  If name p is a directory in the index, do not return
626  * anything, as we will want to match it when the traversal descends into
627  * the directory.
628  */
629 static int find_cache_pos(struct traverse_info *info,
630                           const struct name_entry *p)
631 {
632         int pos;
633         struct unpack_trees_options *o = info->data;
634         struct index_state *index = o->src_index;
635         int pfxlen = info->pathlen;
636         int p_len = tree_entry_len(p);
637
638         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
639                 struct cache_entry *ce = index->cache[pos];
640                 const char *ce_name, *ce_slash;
641                 int cmp, ce_len;
642
643                 if (ce->ce_flags & CE_UNPACKED) {
644                         /*
645                          * cache_bottom entry is already unpacked, so
646                          * we can never match it; don't check it
647                          * again.
648                          */
649                         if (pos == o->cache_bottom)
650                                 ++o->cache_bottom;
651                         continue;
652                 }
653                 if (!ce_in_traverse_path(ce, info))
654                         continue;
655                 ce_name = ce->name + pfxlen;
656                 ce_slash = strchr(ce_name, '/');
657                 if (ce_slash)
658                         ce_len = ce_slash - ce_name;
659                 else
660                         ce_len = ce_namelen(ce) - pfxlen;
661                 cmp = name_compare(p->path, p_len, ce_name, ce_len);
662                 /*
663                  * Exact match; if we have a directory we need to
664                  * delay returning it.
665                  */
666                 if (!cmp)
667                         return ce_slash ? -2 - pos : pos;
668                 if (0 < cmp)
669                         continue; /* keep looking */
670                 /*
671                  * ce_name sorts after p->path; could it be that we
672                  * have files under p->path directory in the index?
673                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
674                  * have "t/a" in the index.
675                  */
676                 if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
677                     ce_name[p_len] < '/')
678                         continue; /* keep looking */
679                 break;
680         }
681         return -1;
682 }
683
684 static struct cache_entry *find_cache_entry(struct traverse_info *info,
685                                             const struct name_entry *p)
686 {
687         int pos = find_cache_pos(info, p);
688         struct unpack_trees_options *o = info->data;
689
690         if (0 <= pos)
691                 return o->src_index->cache[pos];
692         else
693                 return NULL;
694 }
695
696 static void debug_path(struct traverse_info *info)
697 {
698         if (info->prev) {
699                 debug_path(info->prev);
700                 if (*info->prev->name.path)
701                         putchar('/');
702         }
703         printf("%s", info->name.path);
704 }
705
706 static void debug_name_entry(int i, struct name_entry *n)
707 {
708         printf("ent#%d %06o %s\n", i,
709                n->path ? n->mode : 0,
710                n->path ? n->path : "(missing)");
711 }
712
713 static void debug_unpack_callback(int n,
714                                   unsigned long mask,
715                                   unsigned long dirmask,
716                                   struct name_entry *names,
717                                   struct traverse_info *info)
718 {
719         int i;
720         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
721                mask, dirmask, n);
722         debug_path(info);
723         putchar('\n');
724         for (i = 0; i < n; i++)
725                 debug_name_entry(i, names + i);
726 }
727
728 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
729 {
730         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
731         struct unpack_trees_options *o = info->data;
732         const struct name_entry *p = names;
733
734         /* Find first entry with a real name (we could use "mask" too) */
735         while (!p->mode)
736                 p++;
737
738         if (o->debug_unpack)
739                 debug_unpack_callback(n, mask, dirmask, names, info);
740
741         /* Are we supposed to look at the index too? */
742         if (o->merge) {
743                 while (1) {
744                         int cmp;
745                         struct cache_entry *ce;
746
747                         if (o->diff_index_cached)
748                                 ce = next_cache_entry(o);
749                         else
750                                 ce = find_cache_entry(info, p);
751
752                         if (!ce)
753                                 break;
754                         cmp = compare_entry(ce, info, p);
755                         if (cmp < 0) {
756                                 if (unpack_index_entry(ce, o) < 0)
757                                         return unpack_failed(o, NULL);
758                                 continue;
759                         }
760                         if (!cmp) {
761                                 if (ce_stage(ce)) {
762                                         /*
763                                          * If we skip unmerged index
764                                          * entries, we'll skip this
765                                          * entry *and* the tree
766                                          * entries associated with it!
767                                          */
768                                         if (o->skip_unmerged) {
769                                                 add_same_unmerged(ce, o);
770                                                 return mask;
771                                         }
772                                 }
773                                 src[0] = ce;
774                         }
775                         break;
776                 }
777         }
778
779         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
780                 return -1;
781
782         if (o->merge && src[0]) {
783                 if (ce_stage(src[0]))
784                         mark_ce_used_same_name(src[0], o);
785                 else
786                         mark_ce_used(src[0], o);
787         }
788
789         /* Now handle any directories.. */
790         if (dirmask) {
791                 unsigned long conflicts = mask & ~dirmask;
792                 if (o->merge) {
793                         conflicts <<= 1;
794                         if (src[0])
795                                 conflicts |= 1;
796                 }
797
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, conflicts,
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                             char *prefix, int prefix_len,
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                               char *prefix, int prefix_len,
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 = excluded_from_list(prefix, prefix_len, basename, &dtype, el);
840
841         prefix[prefix_len++] = '/';
842
843         /* If undecided, use matching result of parent dir in defval */
844         if (ret < 0)
845                 ret = defval;
846
847         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
848                 struct cache_entry *ce = *cache_end;
849                 if (strncmp(ce->name, prefix, prefix_len))
850                         break;
851         }
852
853         /*
854          * TODO: check el, if there are no patterns that may conflict
855          * with ret (iow, we know in advance the incl/excl
856          * decision for the entire directory), clear flag here without
857          * calling clear_ce_flags_1(). That function will call
858          * the expensive excluded_from_list() on every entry.
859          */
860         return clear_ce_flags_1(cache, cache_end - cache,
861                                 prefix, prefix_len,
862                                 select_mask, clear_mask,
863                                 el, ret);
864 }
865
866 /*
867  * Traverse the index, find every entry that matches according to
868  * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
869  * number of traversed entries.
870  *
871  * If select_mask is non-zero, only entries whose ce_flags has on of
872  * those bits enabled are traversed.
873  *
874  * cache        : pointer to an index entry
875  * prefix_len   : an offset to its path
876  *
877  * The current path ("prefix") including the trailing '/' is
878  *   cache[0]->name[0..(prefix_len-1)]
879  * Top level path has prefix_len zero.
880  */
881 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
882                             char *prefix, int prefix_len,
883                             int select_mask, int clear_mask,
884                             struct exclude_list *el, int defval)
885 {
886         struct cache_entry **cache_end = cache + nr;
887
888         /*
889          * Process all entries that have the given prefix and meet
890          * select_mask condition
891          */
892         while(cache != cache_end) {
893                 struct cache_entry *ce = *cache;
894                 const char *name, *slash;
895                 int len, dtype, ret;
896
897                 if (select_mask && !(ce->ce_flags & select_mask)) {
898                         cache++;
899                         continue;
900                 }
901
902                 if (prefix_len && strncmp(ce->name, prefix, prefix_len))
903                         break;
904
905                 name = ce->name + prefix_len;
906                 slash = strchr(name, '/');
907
908                 /* If it's a directory, try whole directory match first */
909                 if (slash) {
910                         int processed;
911
912                         len = slash - name;
913                         memcpy(prefix + prefix_len, name, len);
914
915                         /*
916                          * terminate the string (no trailing slash),
917                          * clear_c_f_dir needs it
918                          */
919                         prefix[prefix_len + len] = '\0';
920                         processed = clear_ce_flags_dir(cache, cache_end - cache,
921                                                        prefix, prefix_len + len,
922                                                        prefix + prefix_len,
923                                                        select_mask, clear_mask,
924                                                        el, defval);
925
926                         /* clear_c_f_dir eats a whole dir already? */
927                         if (processed) {
928                                 cache += processed;
929                                 continue;
930                         }
931
932                         prefix[prefix_len + len++] = '/';
933                         cache += clear_ce_flags_1(cache, cache_end - cache,
934                                                   prefix, prefix_len + len,
935                                                   select_mask, clear_mask, el, defval);
936                         continue;
937                 }
938
939                 /* Non-directory */
940                 dtype = ce_to_dtype(ce);
941                 ret = excluded_from_list(ce->name, ce_namelen(ce), name, &dtype, el);
942                 if (ret < 0)
943                         ret = defval;
944                 if (ret > 0)
945                         ce->ce_flags &= ~clear_mask;
946                 cache++;
947         }
948         return nr - (cache_end - cache);
949 }
950
951 static int clear_ce_flags(struct cache_entry **cache, int nr,
952                             int select_mask, int clear_mask,
953                             struct exclude_list *el)
954 {
955         char prefix[PATH_MAX];
956         return clear_ce_flags_1(cache, nr,
957                                 prefix, 0,
958                                 select_mask, clear_mask,
959                                 el, 0);
960 }
961
962 /*
963  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
964  */
965 static void mark_new_skip_worktree(struct exclude_list *el,
966                                    struct index_state *the_index,
967                                    int select_flag, int skip_wt_flag)
968 {
969         int i;
970
971         /*
972          * 1. Pretend the narrowest worktree: only unmerged entries
973          * are checked out
974          */
975         for (i = 0; i < the_index->cache_nr; i++) {
976                 struct cache_entry *ce = the_index->cache[i];
977
978                 if (select_flag && !(ce->ce_flags & select_flag))
979                         continue;
980
981                 if (!ce_stage(ce))
982                         ce->ce_flags |= skip_wt_flag;
983                 else
984                         ce->ce_flags &= ~skip_wt_flag;
985         }
986
987         /*
988          * 2. Widen worktree according to sparse-checkout file.
989          * Matched entries will have skip_wt_flag cleared (i.e. "in")
990          */
991         clear_ce_flags(the_index->cache, the_index->cache_nr,
992                        select_flag, skip_wt_flag, el);
993 }
994
995 static int verify_absent(struct cache_entry *, enum unpack_trees_error_types, struct unpack_trees_options *);
996 /*
997  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
998  * resulting index, -2 on failure to reflect the changes to the work tree.
999  *
1000  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1001  */
1002 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1003 {
1004         int i, ret;
1005         static struct cache_entry *dfc;
1006         struct exclude_list el;
1007
1008         if (len > MAX_UNPACK_TREES)
1009                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1010         memset(&state, 0, sizeof(state));
1011         state.base_dir = "";
1012         state.force = 1;
1013         state.quiet = 1;
1014         state.refresh_cache = 1;
1015
1016         memset(&el, 0, sizeof(el));
1017         if (!core_apply_sparse_checkout || !o->update)
1018                 o->skip_sparse_checkout = 1;
1019         if (!o->skip_sparse_checkout) {
1020                 if (add_excludes_from_file_to_list(git_path("info/sparse-checkout"), "", 0, NULL, &el, 0) < 0)
1021                         o->skip_sparse_checkout = 1;
1022                 else
1023                         o->el = &el;
1024         }
1025
1026         if (o->dir) {
1027                 o->path_exclude_check = xmalloc(sizeof(struct path_exclude_check));
1028                 path_exclude_check_init(o->path_exclude_check, o->dir);
1029         }
1030         memset(&o->result, 0, sizeof(o->result));
1031         o->result.initialized = 1;
1032         o->result.timestamp.sec = o->src_index->timestamp.sec;
1033         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1034         o->result.version = o->src_index->version;
1035         o->merge_size = len;
1036         mark_all_ce_unused(o->src_index);
1037
1038         /*
1039          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1040          */
1041         if (!o->skip_sparse_checkout)
1042                 mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1043
1044         if (!dfc)
1045                 dfc = xcalloc(1, cache_entry_size(0));
1046         o->df_conflict_entry = dfc;
1047
1048         if (len) {
1049                 const char *prefix = o->prefix ? o->prefix : "";
1050                 struct traverse_info info;
1051
1052                 setup_traverse_info(&info, prefix);
1053                 info.fn = unpack_callback;
1054                 info.data = o;
1055                 info.show_all_errors = o->show_all_errors;
1056                 info.pathspec = o->pathspec;
1057
1058                 if (o->prefix) {
1059                         /*
1060                          * Unpack existing index entries that sort before the
1061                          * prefix the tree is spliced into.  Note that o->merge
1062                          * is always true in this case.
1063                          */
1064                         while (1) {
1065                                 struct cache_entry *ce = next_cache_entry(o);
1066                                 if (!ce)
1067                                         break;
1068                                 if (ce_in_traverse_path(ce, &info))
1069                                         break;
1070                                 if (unpack_index_entry(ce, o) < 0)
1071                                         goto return_failed;
1072                         }
1073                 }
1074
1075                 if (traverse_trees(len, t, &info) < 0)
1076                         goto return_failed;
1077         }
1078
1079         /* Any left-over entries in the index? */
1080         if (o->merge) {
1081                 while (1) {
1082                         struct cache_entry *ce = next_cache_entry(o);
1083                         if (!ce)
1084                                 break;
1085                         if (unpack_index_entry(ce, o) < 0)
1086                                 goto return_failed;
1087                 }
1088         }
1089         mark_all_ce_unused(o->src_index);
1090
1091         if (o->trivial_merges_only && o->nontrivial_merge) {
1092                 ret = unpack_failed(o, "Merge requires file-level merging");
1093                 goto done;
1094         }
1095
1096         if (!o->skip_sparse_checkout) {
1097                 int empty_worktree = 1;
1098
1099                 /*
1100                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1101                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1102                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1103                  */
1104                 mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1105
1106                 ret = 0;
1107                 for (i = 0; i < o->result.cache_nr; i++) {
1108                         struct cache_entry *ce = o->result.cache[i];
1109
1110                         /*
1111                          * Entries marked with CE_ADDED in merged_entry() do not have
1112                          * verify_absent() check (the check is effectively disabled
1113                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1114                          *
1115                          * Do the real check now because we have had
1116                          * correct CE_NEW_SKIP_WORKTREE
1117                          */
1118                         if (ce->ce_flags & CE_ADDED &&
1119                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1120                                 if (!o->show_all_errors)
1121                                         goto return_failed;
1122                                 ret = -1;
1123                         }
1124
1125                         if (apply_sparse_checkout(ce, o)) {
1126                                 if (!o->show_all_errors)
1127                                         goto return_failed;
1128                                 ret = -1;
1129                         }
1130                         if (!ce_skip_worktree(ce))
1131                                 empty_worktree = 0;
1132
1133                 }
1134                 if (ret < 0)
1135                         goto return_failed;
1136                 /*
1137                  * Sparse checkout is meant to narrow down checkout area
1138                  * but it does not make sense to narrow down to empty working
1139                  * tree. This is usually a mistake in sparse checkout rules.
1140                  * Do not allow users to do that.
1141                  */
1142                 if (o->result.cache_nr && empty_worktree) {
1143                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1144                         goto done;
1145                 }
1146         }
1147
1148         o->src_index = NULL;
1149         ret = check_updates(o) ? (-2) : 0;
1150         if (o->dst_index)
1151                 *o->dst_index = o->result;
1152
1153 done:
1154         free_excludes(&el);
1155         if (o->path_exclude_check) {
1156                 path_exclude_check_clear(o->path_exclude_check);
1157                 free(o->path_exclude_check);
1158         }
1159         return ret;
1160
1161 return_failed:
1162         if (o->show_all_errors)
1163                 display_error_msgs(o);
1164         mark_all_ce_unused(o->src_index);
1165         ret = unpack_failed(o, NULL);
1166         if (o->exiting_early)
1167                 ret = 0;
1168         goto done;
1169 }
1170
1171 /* Here come the merge functions */
1172
1173 static int reject_merge(struct cache_entry *ce, struct unpack_trees_options *o)
1174 {
1175         return add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1176 }
1177
1178 static int same(struct cache_entry *a, struct cache_entry *b)
1179 {
1180         if (!!a != !!b)
1181                 return 0;
1182         if (!a && !b)
1183                 return 1;
1184         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1185                 return 0;
1186         return a->ce_mode == b->ce_mode &&
1187                !hashcmp(a->sha1, b->sha1);
1188 }
1189
1190
1191 /*
1192  * When a CE gets turned into an unmerged entry, we
1193  * want it to be up-to-date
1194  */
1195 static int verify_uptodate_1(struct cache_entry *ce,
1196                                    struct unpack_trees_options *o,
1197                                    enum unpack_trees_error_types error_type)
1198 {
1199         struct stat st;
1200
1201         if (o->index_only)
1202                 return 0;
1203
1204         /*
1205          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1206          * if this entry is truly up-to-date because this file may be
1207          * overwritten.
1208          */
1209         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1210                 ; /* keep checking */
1211         else if (o->reset || ce_uptodate(ce))
1212                 return 0;
1213
1214         if (!lstat(ce->name, &st)) {
1215                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1216                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1217                 if (!changed)
1218                         return 0;
1219                 /*
1220                  * NEEDSWORK: the current default policy is to allow
1221                  * submodule to be out of sync wrt the superproject
1222                  * index.  This needs to be tightened later for
1223                  * submodules that are marked to be automatically
1224                  * checked out.
1225                  */
1226                 if (S_ISGITLINK(ce->ce_mode))
1227                         return 0;
1228                 errno = 0;
1229         }
1230         if (errno == ENOENT)
1231                 return 0;
1232         return o->gently ? -1 :
1233                 add_rejected_path(o, error_type, ce->name);
1234 }
1235
1236 static int verify_uptodate(struct cache_entry *ce,
1237                            struct unpack_trees_options *o)
1238 {
1239         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1240                 return 0;
1241         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1242 }
1243
1244 static int verify_uptodate_sparse(struct cache_entry *ce,
1245                                   struct unpack_trees_options *o)
1246 {
1247         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1248 }
1249
1250 static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
1251 {
1252         if (ce)
1253                 cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
1254 }
1255
1256 /*
1257  * Check that checking out ce->sha1 in subdir ce->name is not
1258  * going to overwrite any working files.
1259  *
1260  * Currently, git does not checkout subprojects during a superproject
1261  * checkout, so it is not going to overwrite anything.
1262  */
1263 static int verify_clean_submodule(struct cache_entry *ce,
1264                                       enum unpack_trees_error_types error_type,
1265                                       struct unpack_trees_options *o)
1266 {
1267         return 0;
1268 }
1269
1270 static int verify_clean_subdirectory(struct cache_entry *ce,
1271                                       enum unpack_trees_error_types error_type,
1272                                       struct unpack_trees_options *o)
1273 {
1274         /*
1275          * we are about to extract "ce->name"; we would not want to lose
1276          * anything in the existing directory there.
1277          */
1278         int namelen;
1279         int i;
1280         struct dir_struct d;
1281         char *pathbuf;
1282         int cnt = 0;
1283         unsigned char sha1[20];
1284
1285         if (S_ISGITLINK(ce->ce_mode) &&
1286             resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
1287                 /* If we are not going to update the submodule, then
1288                  * we don't care.
1289                  */
1290                 if (!hashcmp(sha1, ce->sha1))
1291                         return 0;
1292                 return verify_clean_submodule(ce, error_type, o);
1293         }
1294
1295         /*
1296          * First let's make sure we do not have a local modification
1297          * in that directory.
1298          */
1299         namelen = strlen(ce->name);
1300         for (i = locate_in_src_index(ce, o);
1301              i < o->src_index->cache_nr;
1302              i++) {
1303                 struct cache_entry *ce2 = o->src_index->cache[i];
1304                 int len = ce_namelen(ce2);
1305                 if (len < namelen ||
1306                     strncmp(ce->name, ce2->name, namelen) ||
1307                     ce2->name[namelen] != '/')
1308                         break;
1309                 /*
1310                  * ce2->name is an entry in the subdirectory to be
1311                  * removed.
1312                  */
1313                 if (!ce_stage(ce2)) {
1314                         if (verify_uptodate(ce2, o))
1315                                 return -1;
1316                         add_entry(o, ce2, CE_REMOVE, 0);
1317                         mark_ce_used(ce2, o);
1318                 }
1319                 cnt++;
1320         }
1321
1322         /*
1323          * Then we need to make sure that we do not lose a locally
1324          * present file that is not ignored.
1325          */
1326         pathbuf = xmalloc(namelen + 2);
1327         memcpy(pathbuf, ce->name, namelen);
1328         strcpy(pathbuf+namelen, "/");
1329
1330         memset(&d, 0, sizeof(d));
1331         if (o->dir)
1332                 d.exclude_per_dir = o->dir->exclude_per_dir;
1333         i = read_directory(&d, pathbuf, namelen+1, NULL);
1334         if (i)
1335                 return o->gently ? -1 :
1336                         add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1337         free(pathbuf);
1338         return cnt;
1339 }
1340
1341 /*
1342  * This gets called when there was no index entry for the tree entry 'dst',
1343  * but we found a file in the working tree that 'lstat()' said was fine,
1344  * and we're on a case-insensitive filesystem.
1345  *
1346  * See if we can find a case-insensitive match in the index that also
1347  * matches the stat information, and assume it's that other file!
1348  */
1349 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1350 {
1351         struct cache_entry *src;
1352
1353         src = index_name_exists(o->src_index, name, len, 1);
1354         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1355 }
1356
1357 static int check_ok_to_remove(const char *name, int len, int dtype,
1358                               struct cache_entry *ce, struct stat *st,
1359                               enum unpack_trees_error_types error_type,
1360                               struct unpack_trees_options *o)
1361 {
1362         struct cache_entry *result;
1363
1364         /*
1365          * It may be that the 'lstat()' succeeded even though
1366          * target 'ce' was absent, because there is an old
1367          * entry that is different only in case..
1368          *
1369          * Ignore that lstat() if it matches.
1370          */
1371         if (ignore_case && icase_exists(o, name, len, st))
1372                 return 0;
1373
1374         if (o->dir &&
1375             path_excluded(o->path_exclude_check, name, -1, &dtype))
1376                 /*
1377                  * ce->name is explicitly excluded, so it is Ok to
1378                  * overwrite it.
1379                  */
1380                 return 0;
1381         if (S_ISDIR(st->st_mode)) {
1382                 /*
1383                  * We are checking out path "foo" and
1384                  * found "foo/." in the working tree.
1385                  * This is tricky -- if we have modified
1386                  * files that are in "foo/" we would lose
1387                  * them.
1388                  */
1389                 if (verify_clean_subdirectory(ce, error_type, o) < 0)
1390                         return -1;
1391                 return 0;
1392         }
1393
1394         /*
1395          * The previous round may already have decided to
1396          * delete this path, which is in a subdirectory that
1397          * is being replaced with a blob.
1398          */
1399         result = index_name_exists(&o->result, name, len, 0);
1400         if (result) {
1401                 if (result->ce_flags & CE_REMOVE)
1402                         return 0;
1403         }
1404
1405         return o->gently ? -1 :
1406                 add_rejected_path(o, error_type, name);
1407 }
1408
1409 /*
1410  * We do not want to remove or overwrite a working tree file that
1411  * is not tracked, unless it is ignored.
1412  */
1413 static int verify_absent_1(struct cache_entry *ce,
1414                                  enum unpack_trees_error_types error_type,
1415                                  struct unpack_trees_options *o)
1416 {
1417         int len;
1418         struct stat st;
1419
1420         if (o->index_only || o->reset || !o->update)
1421                 return 0;
1422
1423         len = check_leading_path(ce->name, ce_namelen(ce));
1424         if (!len)
1425                 return 0;
1426         else if (len > 0) {
1427                 char path[PATH_MAX + 1];
1428                 memcpy(path, ce->name, len);
1429                 path[len] = 0;
1430                 if (lstat(path, &st))
1431                         return error("cannot stat '%s': %s", path,
1432                                         strerror(errno));
1433
1434                 return check_ok_to_remove(path, len, DT_UNKNOWN, NULL, &st,
1435                                 error_type, o);
1436         } else if (lstat(ce->name, &st)) {
1437                 if (errno != ENOENT)
1438                         return error("cannot stat '%s': %s", ce->name,
1439                                      strerror(errno));
1440                 return 0;
1441         } else {
1442                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1443                                           ce_to_dtype(ce), ce, &st,
1444                                           error_type, o);
1445         }
1446 }
1447
1448 static int verify_absent(struct cache_entry *ce,
1449                          enum unpack_trees_error_types error_type,
1450                          struct unpack_trees_options *o)
1451 {
1452         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1453                 return 0;
1454         return verify_absent_1(ce, error_type, o);
1455 }
1456
1457 static int verify_absent_sparse(struct cache_entry *ce,
1458                          enum unpack_trees_error_types error_type,
1459                          struct unpack_trees_options *o)
1460 {
1461         enum unpack_trees_error_types orphaned_error = error_type;
1462         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1463                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1464
1465         return verify_absent_1(ce, orphaned_error, o);
1466 }
1467
1468 static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
1469                 struct unpack_trees_options *o)
1470 {
1471         int update = CE_UPDATE;
1472
1473         if (!old) {
1474                 /*
1475                  * New index entries. In sparse checkout, the following
1476                  * verify_absent() will be delayed until after
1477                  * traverse_trees() finishes in unpack_trees(), then:
1478                  *
1479                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1480                  *  - verify_absent() be called again, this time with
1481                  *    correct CE_NEW_SKIP_WORKTREE
1482                  *
1483                  * verify_absent() call here does nothing in sparse
1484                  * checkout (i.e. o->skip_sparse_checkout == 0)
1485                  */
1486                 update |= CE_ADDED;
1487                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1488
1489                 if (verify_absent(merge, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
1490                         return -1;
1491                 invalidate_ce_path(merge, o);
1492         } else if (!(old->ce_flags & CE_CONFLICTED)) {
1493                 /*
1494                  * See if we can re-use the old CE directly?
1495                  * That way we get the uptodate stat info.
1496                  *
1497                  * This also removes the UPDATE flag on a match; otherwise
1498                  * we will end up overwriting local changes in the work tree.
1499                  */
1500                 if (same(old, merge)) {
1501                         copy_cache_entry(merge, old);
1502                         update = 0;
1503                 } else {
1504                         if (verify_uptodate(old, o))
1505                                 return -1;
1506                         /* Migrate old flags over */
1507                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1508                         invalidate_ce_path(old, o);
1509                 }
1510         } else {
1511                 /*
1512                  * Previously unmerged entry left as an existence
1513                  * marker by read_index_unmerged();
1514                  */
1515                 invalidate_ce_path(old, o);
1516         }
1517
1518         add_entry(o, merge, update, CE_STAGEMASK);
1519         return 1;
1520 }
1521
1522 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
1523                 struct unpack_trees_options *o)
1524 {
1525         /* Did it exist in the index? */
1526         if (!old) {
1527                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1528                         return -1;
1529                 return 0;
1530         }
1531         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1532                 return -1;
1533         add_entry(o, ce, CE_REMOVE, 0);
1534         invalidate_ce_path(ce, o);
1535         return 1;
1536 }
1537
1538 static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
1539 {
1540         add_entry(o, ce, 0, 0);
1541         return 1;
1542 }
1543
1544 #if DBRT_DEBUG
1545 static void show_stage_entry(FILE *o,
1546                              const char *label, const struct cache_entry *ce)
1547 {
1548         if (!ce)
1549                 fprintf(o, "%s (missing)\n", label);
1550         else
1551                 fprintf(o, "%s%06o %s %d\t%s\n",
1552                         label,
1553                         ce->ce_mode,
1554                         sha1_to_hex(ce->sha1),
1555                         ce_stage(ce),
1556                         ce->name);
1557 }
1558 #endif
1559
1560 int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
1561 {
1562         struct cache_entry *index;
1563         struct cache_entry *head;
1564         struct cache_entry *remote = stages[o->head_idx + 1];
1565         int count;
1566         int head_match = 0;
1567         int remote_match = 0;
1568
1569         int df_conflict_head = 0;
1570         int df_conflict_remote = 0;
1571
1572         int any_anc_missing = 0;
1573         int no_anc_exists = 1;
1574         int i;
1575
1576         for (i = 1; i < o->head_idx; i++) {
1577                 if (!stages[i] || stages[i] == o->df_conflict_entry)
1578                         any_anc_missing = 1;
1579                 else
1580                         no_anc_exists = 0;
1581         }
1582
1583         index = stages[0];
1584         head = stages[o->head_idx];
1585
1586         if (head == o->df_conflict_entry) {
1587                 df_conflict_head = 1;
1588                 head = NULL;
1589         }
1590
1591         if (remote == o->df_conflict_entry) {
1592                 df_conflict_remote = 1;
1593                 remote = NULL;
1594         }
1595
1596         /*
1597          * First, if there's a #16 situation, note that to prevent #13
1598          * and #14.
1599          */
1600         if (!same(remote, head)) {
1601                 for (i = 1; i < o->head_idx; i++) {
1602                         if (same(stages[i], head)) {
1603                                 head_match = i;
1604                         }
1605                         if (same(stages[i], remote)) {
1606                                 remote_match = i;
1607                         }
1608                 }
1609         }
1610
1611         /*
1612          * We start with cases where the index is allowed to match
1613          * something other than the head: #14(ALT) and #2ALT, where it
1614          * is permitted to match the result instead.
1615          */
1616         /* #14, #14ALT, #2ALT */
1617         if (remote && !df_conflict_head && head_match && !remote_match) {
1618                 if (index && !same(index, remote) && !same(index, head))
1619                         return o->gently ? -1 : reject_merge(index, o);
1620                 return merged_entry(remote, index, o);
1621         }
1622         /*
1623          * If we have an entry in the index cache, then we want to
1624          * make sure that it matches head.
1625          */
1626         if (index && !same(index, head))
1627                 return o->gently ? -1 : reject_merge(index, o);
1628
1629         if (head) {
1630                 /* #5ALT, #15 */
1631                 if (same(head, remote))
1632                         return merged_entry(head, index, o);
1633                 /* #13, #3ALT */
1634                 if (!df_conflict_remote && remote_match && !head_match)
1635                         return merged_entry(head, index, o);
1636         }
1637
1638         /* #1 */
1639         if (!head && !remote && any_anc_missing)
1640                 return 0;
1641
1642         /*
1643          * Under the "aggressive" rule, we resolve mostly trivial
1644          * cases that we historically had git-merge-one-file resolve.
1645          */
1646         if (o->aggressive) {
1647                 int head_deleted = !head;
1648                 int remote_deleted = !remote;
1649                 struct cache_entry *ce = NULL;
1650
1651                 if (index)
1652                         ce = index;
1653                 else if (head)
1654                         ce = head;
1655                 else if (remote)
1656                         ce = remote;
1657                 else {
1658                         for (i = 1; i < o->head_idx; i++) {
1659                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
1660                                         ce = stages[i];
1661                                         break;
1662                                 }
1663                         }
1664                 }
1665
1666                 /*
1667                  * Deleted in both.
1668                  * Deleted in one and unchanged in the other.
1669                  */
1670                 if ((head_deleted && remote_deleted) ||
1671                     (head_deleted && remote && remote_match) ||
1672                     (remote_deleted && head && head_match)) {
1673                         if (index)
1674                                 return deleted_entry(index, index, o);
1675                         if (ce && !head_deleted) {
1676                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1677                                         return -1;
1678                         }
1679                         return 0;
1680                 }
1681                 /*
1682                  * Added in both, identically.
1683                  */
1684                 if (no_anc_exists && head && remote && same(head, remote))
1685                         return merged_entry(head, index, o);
1686
1687         }
1688
1689         /* Below are "no merge" cases, which require that the index be
1690          * up-to-date to avoid the files getting overwritten with
1691          * conflict resolution files.
1692          */
1693         if (index) {
1694                 if (verify_uptodate(index, o))
1695                         return -1;
1696         }
1697
1698         o->nontrivial_merge = 1;
1699
1700         /* #2, #3, #4, #6, #7, #9, #10, #11. */
1701         count = 0;
1702         if (!head_match || !remote_match) {
1703                 for (i = 1; i < o->head_idx; i++) {
1704                         if (stages[i] && stages[i] != o->df_conflict_entry) {
1705                                 keep_entry(stages[i], o);
1706                                 count++;
1707                                 break;
1708                         }
1709                 }
1710         }
1711 #if DBRT_DEBUG
1712         else {
1713                 fprintf(stderr, "read-tree: warning #16 detected\n");
1714                 show_stage_entry(stderr, "head   ", stages[head_match]);
1715                 show_stage_entry(stderr, "remote ", stages[remote_match]);
1716         }
1717 #endif
1718         if (head) { count += keep_entry(head, o); }
1719         if (remote) { count += keep_entry(remote, o); }
1720         return count;
1721 }
1722
1723 /*
1724  * Two-way merge.
1725  *
1726  * The rule is to "carry forward" what is in the index without losing
1727  * information across a "fast-forward", favoring a successful merge
1728  * over a merge failure when it makes sense.  For details of the
1729  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
1730  *
1731  */
1732 int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1733 {
1734         struct cache_entry *current = src[0];
1735         struct cache_entry *oldtree = src[1];
1736         struct cache_entry *newtree = src[2];
1737
1738         if (o->merge_size != 2)
1739                 return error("Cannot do a twoway merge of %d trees",
1740                              o->merge_size);
1741
1742         if (oldtree == o->df_conflict_entry)
1743                 oldtree = NULL;
1744         if (newtree == o->df_conflict_entry)
1745                 newtree = NULL;
1746
1747         if (current) {
1748                 if ((!oldtree && !newtree) || /* 4 and 5 */
1749                     (!oldtree && newtree &&
1750                      same(current, newtree)) || /* 6 and 7 */
1751                     (oldtree && newtree &&
1752                      same(oldtree, newtree)) || /* 14 and 15 */
1753                     (oldtree && newtree &&
1754                      !same(oldtree, newtree) && /* 18 and 19 */
1755                      same(current, newtree))) {
1756                         return keep_entry(current, o);
1757                 }
1758                 else if (oldtree && !newtree && same(current, oldtree)) {
1759                         /* 10 or 11 */
1760                         return deleted_entry(oldtree, current, o);
1761                 }
1762                 else if (oldtree && newtree &&
1763                          same(current, oldtree) && !same(current, newtree)) {
1764                         /* 20 or 21 */
1765                         return merged_entry(newtree, current, o);
1766                 }
1767                 else {
1768                         /* all other failures */
1769                         if (oldtree)
1770                                 return o->gently ? -1 : reject_merge(oldtree, o);
1771                         if (current)
1772                                 return o->gently ? -1 : reject_merge(current, o);
1773                         if (newtree)
1774                                 return o->gently ? -1 : reject_merge(newtree, o);
1775                         return -1;
1776                 }
1777         }
1778         else if (newtree) {
1779                 if (oldtree && !o->initial_checkout) {
1780                         /*
1781                          * deletion of the path was staged;
1782                          */
1783                         if (same(oldtree, newtree))
1784                                 return 1;
1785                         return reject_merge(oldtree, o);
1786                 }
1787                 return merged_entry(newtree, current, o);
1788         }
1789         return deleted_entry(oldtree, current, o);
1790 }
1791
1792 /*
1793  * Bind merge.
1794  *
1795  * Keep the index entries at stage0, collapse stage1 but make sure
1796  * stage0 does not have anything there.
1797  */
1798 int bind_merge(struct cache_entry **src,
1799                 struct unpack_trees_options *o)
1800 {
1801         struct cache_entry *old = src[0];
1802         struct cache_entry *a = src[1];
1803
1804         if (o->merge_size != 1)
1805                 return error("Cannot do a bind merge of %d trees",
1806                              o->merge_size);
1807         if (a && old)
1808                 return o->gently ? -1 :
1809                         error(ERRORMSG(o, ERROR_BIND_OVERLAP), a->name, old->name);
1810         if (!a)
1811                 return keep_entry(old, o);
1812         else
1813                 return merged_entry(a, NULL, o);
1814 }
1815
1816 /*
1817  * One-way merge.
1818  *
1819  * The rule is:
1820  * - take the stat information from stage0, take the data from stage1
1821  */
1822 int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1823 {
1824         struct cache_entry *old = src[0];
1825         struct cache_entry *a = src[1];
1826
1827         if (o->merge_size != 1)
1828                 return error("Cannot do a oneway merge of %d trees",
1829                              o->merge_size);
1830
1831         if (!a || a == o->df_conflict_entry)
1832                 return deleted_entry(old, old, o);
1833
1834         if (old && same(old, a)) {
1835                 int update = 0;
1836                 if (o->reset && !ce_uptodate(old) && !ce_skip_worktree(old)) {
1837                         struct stat st;
1838                         if (lstat(old->name, &st) ||
1839                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
1840                                 update |= CE_UPDATE;
1841                 }
1842                 add_entry(o, old, update, 0);
1843                 return 0;
1844         }
1845         return merged_entry(a, old, o);
1846 }