Merge branch 'jc/ignore-sigpipe-while-running-hooks'
[git] / unpack-trees.c
1 #define NO_THE_INDEX_COMPATIBILITY_MACROS
2 #include "cache.h"
3 #include "dir.h"
4 #include "tree.h"
5 #include "tree-walk.h"
6 #include "cache-tree.h"
7 #include "unpack-trees.h"
8 #include "progress.h"
9 #include "refs.h"
10 #include "attr.h"
11 #include "split-index.h"
12
13 /*
14  * Error messages expected by scripts out of plumbing commands such as
15  * read-tree.  Non-scripted Porcelain is not required to use these messages
16  * and in fact are encouraged to reword them to better suit their particular
17  * situation better.  See how "git checkout" and "git merge" replaces
18  * them using setup_unpack_trees_porcelain(), for example.
19  */
20 static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
21         /* ERROR_WOULD_OVERWRITE */
22         "Entry '%s' would be overwritten by merge. Cannot merge.",
23
24         /* ERROR_NOT_UPTODATE_FILE */
25         "Entry '%s' not uptodate. Cannot merge.",
26
27         /* ERROR_NOT_UPTODATE_DIR */
28         "Updating '%s' would lose untracked files in it",
29
30         /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
31         "Untracked working tree file '%s' would be overwritten by merge.",
32
33         /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
34         "Untracked working tree file '%s' would be removed by merge.",
35
36         /* ERROR_BIND_OVERLAP */
37         "Entry '%s' overlaps with '%s'.  Cannot bind.",
38
39         /* ERROR_SPARSE_NOT_UPTODATE_FILE */
40         "Entry '%s' not uptodate. Cannot update sparse checkout.",
41
42         /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
43         "Working tree file '%s' would be overwritten by sparse checkout update.",
44
45         /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
46         "Working tree file '%s' would be removed by sparse checkout update.",
47 };
48
49 #define ERRORMSG(o,type) \
50         ( ((o) && (o)->msgs[(type)]) \
51           ? ((o)->msgs[(type)])      \
52           : (unpack_plumbing_errors[(type)]) )
53
54 void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
55                                   const char *cmd)
56 {
57         int i;
58         const char **msgs = opts->msgs;
59         const char *msg;
60         const char *cmd2 = strcmp(cmd, "checkout") ? cmd : "switch branches";
61
62         if (advice_commit_before_merge)
63                 msg = "Your local changes to the following files would be overwritten by %s:\n%%s"
64                         "Please, commit your changes or stash them before you can %s.";
65         else
66                 msg = "Your local changes to the following files would be overwritten by %s:\n%%s";
67         msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
68                 xstrfmt(msg, cmd, cmd2);
69
70         msgs[ERROR_NOT_UPTODATE_DIR] =
71                 "Updating the following directories would lose untracked files in it:\n%s";
72
73         if (advice_commit_before_merge)
74                 msg = "The following untracked working tree files would be %s by %s:\n%%s"
75                         "Please move or remove them before you can %s.";
76         else
77                 msg = "The following untracked working tree files would be %s by %s:\n%%s";
78
79         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = xstrfmt(msg, "removed", cmd, cmd2);
80         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = xstrfmt(msg, "overwritten", cmd, cmd2);
81
82         /*
83          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
84          * cannot easily display it as a list.
85          */
86         msgs[ERROR_BIND_OVERLAP] = "Entry '%s' overlaps with '%s'.  Cannot bind.";
87
88         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
89                 "Cannot update sparse checkout: the following entries are not up-to-date:\n%s";
90         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
91                 "The following Working tree files would be overwritten by sparse checkout update:\n%s";
92         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
93                 "The following Working tree files would be removed by sparse checkout update:\n%s";
94
95         opts->show_all_errors = 1;
96         /* rejected paths may not have a static buffer */
97         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
98                 opts->unpack_rejects[i].strdup_strings = 1;
99 }
100
101 static void do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
102                          unsigned int set, unsigned int clear)
103 {
104         clear |= CE_HASHED;
105
106         if (set & CE_REMOVE)
107                 set |= CE_WT_REMOVE;
108
109         ce->ce_flags = (ce->ce_flags & ~clear) | set;
110         add_index_entry(&o->result, ce,
111                         ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
112 }
113
114 static struct cache_entry *dup_entry(const struct cache_entry *ce)
115 {
116         unsigned int size = ce_size(ce);
117         struct cache_entry *new = xmalloc(size);
118
119         memcpy(new, ce, size);
120         return new;
121 }
122
123 static void add_entry(struct unpack_trees_options *o,
124                       const struct cache_entry *ce,
125                       unsigned int set, unsigned int clear)
126 {
127         do_add_entry(o, dup_entry(ce), set, clear);
128 }
129
130 /*
131  * add error messages on path <path>
132  * corresponding to the type <e> with the message <msg>
133  * indicating if it should be display in porcelain or not
134  */
135 static int add_rejected_path(struct unpack_trees_options *o,
136                              enum unpack_trees_error_types e,
137                              const char *path)
138 {
139         if (!o->show_all_errors)
140                 return error(ERRORMSG(o, e), path);
141
142         /*
143          * Otherwise, insert in a list for future display by
144          * display_error_msgs()
145          */
146         string_list_append(&o->unpack_rejects[e], path);
147         return -1;
148 }
149
150 /*
151  * display all the error messages stored in a nice way
152  */
153 static void display_error_msgs(struct unpack_trees_options *o)
154 {
155         int e, i;
156         int something_displayed = 0;
157         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
158                 struct string_list *rejects = &o->unpack_rejects[e];
159                 if (rejects->nr > 0) {
160                         struct strbuf path = STRBUF_INIT;
161                         something_displayed = 1;
162                         for (i = 0; i < rejects->nr; i++)
163                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
164                         error(ERRORMSG(o, e), path.buf);
165                         strbuf_release(&path);
166                 }
167                 string_list_clear(rejects, 0);
168         }
169         if (something_displayed)
170                 fprintf(stderr, "Aborting\n");
171 }
172
173 /*
174  * Unlink the last component and schedule the leading directories for
175  * removal, such that empty directories get removed.
176  */
177 static void unlink_entry(const struct cache_entry *ce)
178 {
179         if (!check_leading_path(ce->name, ce_namelen(ce)))
180                 return;
181         if (remove_or_warn(ce->ce_mode, ce->name))
182                 return;
183         schedule_dir_for_removal(ce->name, ce_namelen(ce));
184 }
185
186 static struct checkout state;
187 static int check_updates(struct unpack_trees_options *o)
188 {
189         unsigned cnt = 0, total = 0;
190         struct progress *progress = NULL;
191         struct index_state *index = &o->result;
192         int i;
193         int errs = 0;
194
195         if (o->update && o->verbose_update) {
196                 for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
197                         const struct cache_entry *ce = index->cache[cnt];
198                         if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
199                                 total++;
200                 }
201
202                 progress = start_progress_delay(_("Checking out files"),
203                                                 total, 50, 1);
204                 cnt = 0;
205         }
206
207         if (o->update)
208                 git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
209         for (i = 0; i < index->cache_nr; i++) {
210                 const struct cache_entry *ce = index->cache[i];
211
212                 if (ce->ce_flags & CE_WT_REMOVE) {
213                         display_progress(progress, ++cnt);
214                         if (o->update && !o->dry_run)
215                                 unlink_entry(ce);
216                         continue;
217                 }
218         }
219         remove_marked_cache_entries(&o->result);
220         remove_scheduled_dirs();
221
222         for (i = 0; i < index->cache_nr; i++) {
223                 struct cache_entry *ce = index->cache[i];
224
225                 if (ce->ce_flags & CE_UPDATE) {
226                         display_progress(progress, ++cnt);
227                         ce->ce_flags &= ~CE_UPDATE;
228                         if (o->update && !o->dry_run) {
229                                 errs |= checkout_entry(ce, &state, NULL);
230                         }
231                 }
232         }
233         stop_progress(&progress);
234         if (o->update)
235                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
236         return errs != 0;
237 }
238
239 static int verify_uptodate_sparse(const struct cache_entry *ce,
240                                   struct unpack_trees_options *o);
241 static int verify_absent_sparse(const struct cache_entry *ce,
242                                 enum unpack_trees_error_types,
243                                 struct unpack_trees_options *o);
244
245 static int apply_sparse_checkout(struct index_state *istate,
246                                  struct cache_entry *ce,
247                                  struct unpack_trees_options *o)
248 {
249         int was_skip_worktree = ce_skip_worktree(ce);
250
251         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
252                 ce->ce_flags |= CE_SKIP_WORKTREE;
253         else
254                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
255         if (was_skip_worktree != ce_skip_worktree(ce)) {
256                 ce->ce_flags |= CE_UPDATE_IN_BASE;
257                 istate->cache_changed |= CE_ENTRY_CHANGED;
258         }
259
260         /*
261          * if (!was_skip_worktree && !ce_skip_worktree()) {
262          *      This is perfectly normal. Move on;
263          * }
264          */
265
266         /*
267          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
268          * area as a result of ce_skip_worktree() shortcuts in
269          * verify_absent() and verify_uptodate().
270          * Make sure they don't modify worktree if they are already
271          * outside checkout area
272          */
273         if (was_skip_worktree && ce_skip_worktree(ce)) {
274                 ce->ce_flags &= ~CE_UPDATE;
275
276                 /*
277                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
278                  * on to get that file removed from both index and worktree.
279                  * If that file is already outside worktree area, don't
280                  * bother remove it.
281                  */
282                 if (ce->ce_flags & CE_REMOVE)
283                         ce->ce_flags &= ~CE_WT_REMOVE;
284         }
285
286         if (!was_skip_worktree && ce_skip_worktree(ce)) {
287                 /*
288                  * If CE_UPDATE is set, verify_uptodate() must be called already
289                  * also stat info may have lost after merged_entry() so calling
290                  * verify_uptodate() again may fail
291                  */
292                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
293                         return -1;
294                 ce->ce_flags |= CE_WT_REMOVE;
295         }
296         if (was_skip_worktree && !ce_skip_worktree(ce)) {
297                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
298                         return -1;
299                 ce->ce_flags |= CE_UPDATE;
300         }
301         return 0;
302 }
303
304 static inline int call_unpack_fn(const struct cache_entry * const *src,
305                                  struct unpack_trees_options *o)
306 {
307         int ret = o->fn(src, o);
308         if (ret > 0)
309                 ret = 0;
310         return ret;
311 }
312
313 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
314 {
315         ce->ce_flags |= CE_UNPACKED;
316
317         if (o->cache_bottom < o->src_index->cache_nr &&
318             o->src_index->cache[o->cache_bottom] == ce) {
319                 int bottom = o->cache_bottom;
320                 while (bottom < o->src_index->cache_nr &&
321                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
322                         bottom++;
323                 o->cache_bottom = bottom;
324         }
325 }
326
327 static void mark_all_ce_unused(struct index_state *index)
328 {
329         int i;
330         for (i = 0; i < index->cache_nr; i++)
331                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
332 }
333
334 static int locate_in_src_index(const struct cache_entry *ce,
335                                struct unpack_trees_options *o)
336 {
337         struct index_state *index = o->src_index;
338         int len = ce_namelen(ce);
339         int pos = index_name_pos(index, ce->name, len);
340         if (pos < 0)
341                 pos = -1 - pos;
342         return pos;
343 }
344
345 /*
346  * We call unpack_index_entry() with an unmerged cache entry
347  * only in diff-index, and it wants a single callback.  Skip
348  * the other unmerged entry with the same name.
349  */
350 static void mark_ce_used_same_name(struct cache_entry *ce,
351                                    struct unpack_trees_options *o)
352 {
353         struct index_state *index = o->src_index;
354         int len = ce_namelen(ce);
355         int pos;
356
357         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
358                 struct cache_entry *next = index->cache[pos];
359                 if (len != ce_namelen(next) ||
360                     memcmp(ce->name, next->name, len))
361                         break;
362                 mark_ce_used(next, o);
363         }
364 }
365
366 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
367 {
368         const struct index_state *index = o->src_index;
369         int pos = o->cache_bottom;
370
371         while (pos < index->cache_nr) {
372                 struct cache_entry *ce = index->cache[pos];
373                 if (!(ce->ce_flags & CE_UNPACKED))
374                         return ce;
375                 pos++;
376         }
377         return NULL;
378 }
379
380 static void add_same_unmerged(const struct cache_entry *ce,
381                               struct unpack_trees_options *o)
382 {
383         struct index_state *index = o->src_index;
384         int len = ce_namelen(ce);
385         int pos = index_name_pos(index, ce->name, len);
386
387         if (0 <= pos)
388                 die("programming error in a caller of mark_ce_used_same_name");
389         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
390                 struct cache_entry *next = index->cache[pos];
391                 if (len != ce_namelen(next) ||
392                     memcmp(ce->name, next->name, len))
393                         break;
394                 add_entry(o, next, 0, 0);
395                 mark_ce_used(next, o);
396         }
397 }
398
399 static int unpack_index_entry(struct cache_entry *ce,
400                               struct unpack_trees_options *o)
401 {
402         const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
403         int ret;
404
405         src[0] = ce;
406
407         mark_ce_used(ce, o);
408         if (ce_stage(ce)) {
409                 if (o->skip_unmerged) {
410                         add_entry(o, ce, 0, 0);
411                         return 0;
412                 }
413         }
414         ret = call_unpack_fn(src, o);
415         if (ce_stage(ce))
416                 mark_ce_used_same_name(ce, o);
417         return ret;
418 }
419
420 static int find_cache_pos(struct traverse_info *, const struct name_entry *);
421
422 static void restore_cache_bottom(struct traverse_info *info, int bottom)
423 {
424         struct unpack_trees_options *o = info->data;
425
426         if (o->diff_index_cached)
427                 return;
428         o->cache_bottom = bottom;
429 }
430
431 static int switch_cache_bottom(struct traverse_info *info)
432 {
433         struct unpack_trees_options *o = info->data;
434         int ret, pos;
435
436         if (o->diff_index_cached)
437                 return 0;
438         ret = o->cache_bottom;
439         pos = find_cache_pos(info->prev, &info->name);
440
441         if (pos < -1)
442                 o->cache_bottom = -2 - pos;
443         else if (pos < 0)
444                 o->cache_bottom = o->src_index->cache_nr;
445         return ret;
446 }
447
448 static int traverse_trees_recursive(int n, unsigned long dirmask,
449                                     unsigned long df_conflicts,
450                                     struct name_entry *names,
451                                     struct traverse_info *info)
452 {
453         int i, ret, bottom;
454         struct tree_desc t[MAX_UNPACK_TREES];
455         void *buf[MAX_UNPACK_TREES];
456         struct traverse_info newinfo;
457         struct name_entry *p;
458
459         p = names;
460         while (!p->mode)
461                 p++;
462
463         newinfo = *info;
464         newinfo.prev = info;
465         newinfo.pathspec = info->pathspec;
466         newinfo.name = *p;
467         newinfo.pathlen += tree_entry_len(p) + 1;
468         newinfo.df_conflicts |= df_conflicts;
469
470         for (i = 0; i < n; i++, dirmask >>= 1) {
471                 const unsigned char *sha1 = NULL;
472                 if (dirmask & 1)
473                         sha1 = names[i].sha1;
474                 buf[i] = fill_tree_descriptor(t+i, sha1);
475         }
476
477         bottom = switch_cache_bottom(&newinfo);
478         ret = traverse_trees(n, t, &newinfo);
479         restore_cache_bottom(&newinfo, bottom);
480
481         for (i = 0; i < n; i++)
482                 free(buf[i]);
483
484         return ret;
485 }
486
487 /*
488  * Compare the traverse-path to the cache entry without actually
489  * having to generate the textual representation of the traverse
490  * path.
491  *
492  * NOTE! This *only* compares up to the size of the traverse path
493  * itself - the caller needs to do the final check for the cache
494  * entry having more data at the end!
495  */
496 static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
497 {
498         int len, pathlen, ce_len;
499         const char *ce_name;
500
501         if (info->prev) {
502                 int cmp = do_compare_entry(ce, info->prev, &info->name);
503                 if (cmp)
504                         return cmp;
505         }
506         pathlen = info->pathlen;
507         ce_len = ce_namelen(ce);
508
509         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
510         if (ce_len < pathlen)
511                 return -1;
512
513         ce_len -= pathlen;
514         ce_name = ce->name + pathlen;
515
516         len = tree_entry_len(n);
517         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
518 }
519
520 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
521 {
522         int cmp = do_compare_entry(ce, info, n);
523         if (cmp)
524                 return cmp;
525
526         /*
527          * Even if the beginning compared identically, the ce should
528          * compare as bigger than a directory leading up to it!
529          */
530         return ce_namelen(ce) > traverse_path_len(info, n);
531 }
532
533 static int ce_in_traverse_path(const struct cache_entry *ce,
534                                const struct traverse_info *info)
535 {
536         if (!info->prev)
537                 return 1;
538         if (do_compare_entry(ce, info->prev, &info->name))
539                 return 0;
540         /*
541          * If ce (blob) is the same name as the path (which is a tree
542          * we will be descending into), it won't be inside it.
543          */
544         return (info->pathlen < ce_namelen(ce));
545 }
546
547 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
548 {
549         int len = traverse_path_len(info, n);
550         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
551
552         ce->ce_mode = create_ce_mode(n->mode);
553         ce->ce_flags = create_ce_flags(stage);
554         ce->ce_namelen = len;
555         hashcpy(ce->sha1, n->sha1);
556         make_traverse_path(ce->name, info, n);
557
558         return ce;
559 }
560
561 static int unpack_nondirectories(int n, unsigned long mask,
562                                  unsigned long dirmask,
563                                  struct cache_entry **src,
564                                  const struct name_entry *names,
565                                  const struct traverse_info *info)
566 {
567         int i;
568         struct unpack_trees_options *o = info->data;
569         unsigned long conflicts = info->df_conflicts | dirmask;
570
571         /* Do we have *only* directories? Nothing to do */
572         if (mask == dirmask && !src[0])
573                 return 0;
574
575         /*
576          * Ok, we've filled in up to any potential index entry in src[0],
577          * now do the rest.
578          */
579         for (i = 0; i < n; i++) {
580                 int stage;
581                 unsigned int bit = 1ul << i;
582                 if (conflicts & bit) {
583                         src[i + o->merge] = o->df_conflict_entry;
584                         continue;
585                 }
586                 if (!(mask & bit))
587                         continue;
588                 if (!o->merge)
589                         stage = 0;
590                 else if (i + 1 < o->head_idx)
591                         stage = 1;
592                 else if (i + 1 > o->head_idx)
593                         stage = 3;
594                 else
595                         stage = 2;
596                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
597         }
598
599         if (o->merge) {
600                 int rc = call_unpack_fn((const struct cache_entry * const *)src,
601                                         o);
602                 for (i = 0; i < n; i++) {
603                         struct cache_entry *ce = src[i + o->merge];
604                         if (ce != o->df_conflict_entry)
605                                 free(ce);
606                 }
607                 return rc;
608         }
609
610         for (i = 0; i < n; i++)
611                 if (src[i] && src[i] != o->df_conflict_entry)
612                         do_add_entry(o, src[i], 0, 0);
613         return 0;
614 }
615
616 static int unpack_failed(struct unpack_trees_options *o, const char *message)
617 {
618         discard_index(&o->result);
619         if (!o->gently && !o->exiting_early) {
620                 if (message)
621                         return error("%s", message);
622                 return -1;
623         }
624         return -1;
625 }
626
627 /*
628  * The tree traversal is looking at name p.  If we have a matching entry,
629  * return it.  If name p is a directory in the index, do not return
630  * anything, as we will want to match it when the traversal descends into
631  * the directory.
632  */
633 static int find_cache_pos(struct traverse_info *info,
634                           const struct name_entry *p)
635 {
636         int pos;
637         struct unpack_trees_options *o = info->data;
638         struct index_state *index = o->src_index;
639         int pfxlen = info->pathlen;
640         int p_len = tree_entry_len(p);
641
642         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
643                 const struct cache_entry *ce = index->cache[pos];
644                 const char *ce_name, *ce_slash;
645                 int cmp, ce_len;
646
647                 if (ce->ce_flags & CE_UNPACKED) {
648                         /*
649                          * cache_bottom entry is already unpacked, so
650                          * we can never match it; don't check it
651                          * again.
652                          */
653                         if (pos == o->cache_bottom)
654                                 ++o->cache_bottom;
655                         continue;
656                 }
657                 if (!ce_in_traverse_path(ce, info))
658                         continue;
659                 ce_name = ce->name + pfxlen;
660                 ce_slash = strchr(ce_name, '/');
661                 if (ce_slash)
662                         ce_len = ce_slash - ce_name;
663                 else
664                         ce_len = ce_namelen(ce) - pfxlen;
665                 cmp = name_compare(p->path, p_len, ce_name, ce_len);
666                 /*
667                  * Exact match; if we have a directory we need to
668                  * delay returning it.
669                  */
670                 if (!cmp)
671                         return ce_slash ? -2 - pos : pos;
672                 if (0 < cmp)
673                         continue; /* keep looking */
674                 /*
675                  * ce_name sorts after p->path; could it be that we
676                  * have files under p->path directory in the index?
677                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
678                  * have "t/a" in the index.
679                  */
680                 if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
681                     ce_name[p_len] < '/')
682                         continue; /* keep looking */
683                 break;
684         }
685         return -1;
686 }
687
688 static struct cache_entry *find_cache_entry(struct traverse_info *info,
689                                             const struct name_entry *p)
690 {
691         int pos = find_cache_pos(info, p);
692         struct unpack_trees_options *o = info->data;
693
694         if (0 <= pos)
695                 return o->src_index->cache[pos];
696         else
697                 return NULL;
698 }
699
700 static void debug_path(struct traverse_info *info)
701 {
702         if (info->prev) {
703                 debug_path(info->prev);
704                 if (*info->prev->name.path)
705                         putchar('/');
706         }
707         printf("%s", info->name.path);
708 }
709
710 static void debug_name_entry(int i, struct name_entry *n)
711 {
712         printf("ent#%d %06o %s\n", i,
713                n->path ? n->mode : 0,
714                n->path ? n->path : "(missing)");
715 }
716
717 static void debug_unpack_callback(int n,
718                                   unsigned long mask,
719                                   unsigned long dirmask,
720                                   struct name_entry *names,
721                                   struct traverse_info *info)
722 {
723         int i;
724         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
725                mask, dirmask, n);
726         debug_path(info);
727         putchar('\n');
728         for (i = 0; i < n; i++)
729                 debug_name_entry(i, names + i);
730 }
731
732 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
733 {
734         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
735         struct unpack_trees_options *o = info->data;
736         const struct name_entry *p = names;
737
738         /* Find first entry with a real name (we could use "mask" too) */
739         while (!p->mode)
740                 p++;
741
742         if (o->debug_unpack)
743                 debug_unpack_callback(n, mask, dirmask, names, info);
744
745         /* Are we supposed to look at the index too? */
746         if (o->merge) {
747                 while (1) {
748                         int cmp;
749                         struct cache_entry *ce;
750
751                         if (o->diff_index_cached)
752                                 ce = next_cache_entry(o);
753                         else
754                                 ce = find_cache_entry(info, p);
755
756                         if (!ce)
757                                 break;
758                         cmp = compare_entry(ce, info, p);
759                         if (cmp < 0) {
760                                 if (unpack_index_entry(ce, o) < 0)
761                                         return unpack_failed(o, NULL);
762                                 continue;
763                         }
764                         if (!cmp) {
765                                 if (ce_stage(ce)) {
766                                         /*
767                                          * If we skip unmerged index
768                                          * entries, we'll skip this
769                                          * entry *and* the tree
770                                          * entries associated with it!
771                                          */
772                                         if (o->skip_unmerged) {
773                                                 add_same_unmerged(ce, o);
774                                                 return mask;
775                                         }
776                                 }
777                                 src[0] = ce;
778                         }
779                         break;
780                 }
781         }
782
783         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
784                 return -1;
785
786         if (o->merge && src[0]) {
787                 if (ce_stage(src[0]))
788                         mark_ce_used_same_name(src[0], o);
789                 else
790                         mark_ce_used(src[0], o);
791         }
792
793         /* Now handle any directories.. */
794         if (dirmask) {
795                 /* special case: "diff-index --cached" looking at a tree */
796                 if (o->diff_index_cached &&
797                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
798                         int matches;
799                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
800                                                                names, info);
801                         /*
802                          * Everything under the name matches; skip the
803                          * entire hierarchy.  diff_index_cached codepath
804                          * special cases D/F conflicts in such a way that
805                          * it does not do any look-ahead, so this is safe.
806                          */
807                         if (matches) {
808                                 o->cache_bottom += matches;
809                                 return mask;
810                         }
811                 }
812
813                 if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
814                                              names, info) < 0)
815                         return -1;
816                 return mask;
817         }
818
819         return mask;
820 }
821
822 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
823                             struct strbuf *prefix,
824                             int select_mask, int clear_mask,
825                             struct exclude_list *el, int defval);
826
827 /* Whole directory matching */
828 static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
829                               struct strbuf *prefix,
830                               char *basename,
831                               int select_mask, int clear_mask,
832                               struct exclude_list *el, int defval)
833 {
834         struct cache_entry **cache_end;
835         int dtype = DT_DIR;
836         int ret = is_excluded_from_list(prefix->buf, prefix->len,
837                                         basename, &dtype, el);
838         int rc;
839
840         strbuf_addch(prefix, '/');
841
842         /* If undecided, use matching result of parent dir in defval */
843         if (ret < 0)
844                 ret = defval;
845
846         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
847                 struct cache_entry *ce = *cache_end;
848                 if (strncmp(ce->name, prefix->buf, prefix->len))
849                         break;
850         }
851
852         /*
853          * TODO: check el, if there are no patterns that may conflict
854          * with ret (iow, we know in advance the incl/excl
855          * decision for the entire directory), clear flag here without
856          * calling clear_ce_flags_1(). That function will call
857          * the expensive is_excluded_from_list() on every entry.
858          */
859         rc = clear_ce_flags_1(cache, cache_end - cache,
860                               prefix,
861                               select_mask, clear_mask,
862                               el, ret);
863         strbuf_setlen(prefix, prefix->len - 1);
864         return rc;
865 }
866
867 /*
868  * Traverse the index, find every entry that matches according to
869  * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
870  * number of traversed entries.
871  *
872  * If select_mask is non-zero, only entries whose ce_flags has on of
873  * those bits enabled are traversed.
874  *
875  * cache        : pointer to an index entry
876  * prefix_len   : an offset to its path
877  *
878  * The current path ("prefix") including the trailing '/' is
879  *   cache[0]->name[0..(prefix_len-1)]
880  * Top level path has prefix_len zero.
881  */
882 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
883                             struct strbuf *prefix,
884                             int select_mask, int clear_mask,
885                             struct exclude_list *el, int defval)
886 {
887         struct cache_entry **cache_end = cache + nr;
888
889         /*
890          * Process all entries that have the given prefix and meet
891          * select_mask condition
892          */
893         while(cache != cache_end) {
894                 struct cache_entry *ce = *cache;
895                 const char *name, *slash;
896                 int len, dtype, ret;
897
898                 if (select_mask && !(ce->ce_flags & select_mask)) {
899                         cache++;
900                         continue;
901                 }
902
903                 if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
904                         break;
905
906                 name = ce->name + prefix->len;
907                 slash = strchr(name, '/');
908
909                 /* If it's a directory, try whole directory match first */
910                 if (slash) {
911                         int processed;
912
913                         len = slash - name;
914                         strbuf_add(prefix, name, len);
915
916                         processed = clear_ce_flags_dir(cache, cache_end - cache,
917                                                        prefix,
918                                                        prefix->buf + prefix->len - len,
919                                                        select_mask, clear_mask,
920                                                        el, defval);
921
922                         /* clear_c_f_dir eats a whole dir already? */
923                         if (processed) {
924                                 cache += processed;
925                                 strbuf_setlen(prefix, prefix->len - len);
926                                 continue;
927                         }
928
929                         strbuf_addch(prefix, '/');
930                         cache += clear_ce_flags_1(cache, cache_end - cache,
931                                                   prefix,
932                                                   select_mask, clear_mask, el, defval);
933                         strbuf_setlen(prefix, prefix->len - len - 1);
934                         continue;
935                 }
936
937                 /* Non-directory */
938                 dtype = ce_to_dtype(ce);
939                 ret = is_excluded_from_list(ce->name, ce_namelen(ce),
940                                             name, &dtype, el);
941                 if (ret < 0)
942                         ret = defval;
943                 if (ret > 0)
944                         ce->ce_flags &= ~clear_mask;
945                 cache++;
946         }
947         return nr - (cache_end - cache);
948 }
949
950 static int clear_ce_flags(struct cache_entry **cache, int nr,
951                             int select_mask, int clear_mask,
952                             struct exclude_list *el)
953 {
954         static struct strbuf prefix = STRBUF_INIT;
955
956         strbuf_reset(&prefix);
957
958         return clear_ce_flags_1(cache, nr,
959                                 &prefix,
960                                 select_mask, clear_mask,
961                                 el, 0);
962 }
963
964 /*
965  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
966  */
967 static void mark_new_skip_worktree(struct exclude_list *el,
968                                    struct index_state *the_index,
969                                    int select_flag, int skip_wt_flag)
970 {
971         int i;
972
973         /*
974          * 1. Pretend the narrowest worktree: only unmerged entries
975          * are checked out
976          */
977         for (i = 0; i < the_index->cache_nr; i++) {
978                 struct cache_entry *ce = the_index->cache[i];
979
980                 if (select_flag && !(ce->ce_flags & select_flag))
981                         continue;
982
983                 if (!ce_stage(ce))
984                         ce->ce_flags |= skip_wt_flag;
985                 else
986                         ce->ce_flags &= ~skip_wt_flag;
987         }
988
989         /*
990          * 2. Widen worktree according to sparse-checkout file.
991          * Matched entries will have skip_wt_flag cleared (i.e. "in")
992          */
993         clear_ce_flags(the_index->cache, the_index->cache_nr,
994                        select_flag, skip_wt_flag, el);
995 }
996
997 static int verify_absent(const struct cache_entry *,
998                          enum unpack_trees_error_types,
999                          struct unpack_trees_options *);
1000 /*
1001  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1002  * resulting index, -2 on failure to reflect the changes to the work tree.
1003  *
1004  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1005  */
1006 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1007 {
1008         int i, ret;
1009         static struct cache_entry *dfc;
1010         struct exclude_list el;
1011
1012         if (len > MAX_UNPACK_TREES)
1013                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1014         memset(&state, 0, sizeof(state));
1015         state.base_dir = "";
1016         state.force = 1;
1017         state.quiet = 1;
1018         state.refresh_cache = 1;
1019         state.istate = &o->result;
1020
1021         memset(&el, 0, sizeof(el));
1022         if (!core_apply_sparse_checkout || !o->update)
1023                 o->skip_sparse_checkout = 1;
1024         if (!o->skip_sparse_checkout) {
1025                 if (add_excludes_from_file_to_list(git_path("info/sparse-checkout"), "", 0, &el, 0) < 0)
1026                         o->skip_sparse_checkout = 1;
1027                 else
1028                         o->el = &el;
1029         }
1030
1031         memset(&o->result, 0, sizeof(o->result));
1032         o->result.initialized = 1;
1033         o->result.timestamp.sec = o->src_index->timestamp.sec;
1034         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1035         o->result.version = o->src_index->version;
1036         o->result.split_index = o->src_index->split_index;
1037         if (o->result.split_index)
1038                 o->result.split_index->refcount++;
1039         hashcpy(o->result.sha1, o->src_index->sha1);
1040         o->merge_size = len;
1041         mark_all_ce_unused(o->src_index);
1042
1043         /*
1044          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1045          */
1046         if (!o->skip_sparse_checkout)
1047                 mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1048
1049         if (!dfc)
1050                 dfc = xcalloc(1, cache_entry_size(0));
1051         o->df_conflict_entry = dfc;
1052
1053         if (len) {
1054                 const char *prefix = o->prefix ? o->prefix : "";
1055                 struct traverse_info info;
1056
1057                 setup_traverse_info(&info, prefix);
1058                 info.fn = unpack_callback;
1059                 info.data = o;
1060                 info.show_all_errors = o->show_all_errors;
1061                 info.pathspec = o->pathspec;
1062
1063                 if (o->prefix) {
1064                         /*
1065                          * Unpack existing index entries that sort before the
1066                          * prefix the tree is spliced into.  Note that o->merge
1067                          * is always true in this case.
1068                          */
1069                         while (1) {
1070                                 struct cache_entry *ce = next_cache_entry(o);
1071                                 if (!ce)
1072                                         break;
1073                                 if (ce_in_traverse_path(ce, &info))
1074                                         break;
1075                                 if (unpack_index_entry(ce, o) < 0)
1076                                         goto return_failed;
1077                         }
1078                 }
1079
1080                 if (traverse_trees(len, t, &info) < 0)
1081                         goto return_failed;
1082         }
1083
1084         /* Any left-over entries in the index? */
1085         if (o->merge) {
1086                 while (1) {
1087                         struct cache_entry *ce = next_cache_entry(o);
1088                         if (!ce)
1089                                 break;
1090                         if (unpack_index_entry(ce, o) < 0)
1091                                 goto return_failed;
1092                 }
1093         }
1094         mark_all_ce_unused(o->src_index);
1095
1096         if (o->trivial_merges_only && o->nontrivial_merge) {
1097                 ret = unpack_failed(o, "Merge requires file-level merging");
1098                 goto done;
1099         }
1100
1101         if (!o->skip_sparse_checkout) {
1102                 int empty_worktree = 1;
1103
1104                 /*
1105                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1106                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1107                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1108                  */
1109                 mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1110
1111                 ret = 0;
1112                 for (i = 0; i < o->result.cache_nr; i++) {
1113                         struct cache_entry *ce = o->result.cache[i];
1114
1115                         /*
1116                          * Entries marked with CE_ADDED in merged_entry() do not have
1117                          * verify_absent() check (the check is effectively disabled
1118                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1119                          *
1120                          * Do the real check now because we have had
1121                          * correct CE_NEW_SKIP_WORKTREE
1122                          */
1123                         if (ce->ce_flags & CE_ADDED &&
1124                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1125                                 if (!o->show_all_errors)
1126                                         goto return_failed;
1127                                 ret = -1;
1128                         }
1129
1130                         if (apply_sparse_checkout(&o->result, ce, o)) {
1131                                 if (!o->show_all_errors)
1132                                         goto return_failed;
1133                                 ret = -1;
1134                         }
1135                         if (!ce_skip_worktree(ce))
1136                                 empty_worktree = 0;
1137
1138                 }
1139                 if (ret < 0)
1140                         goto return_failed;
1141                 /*
1142                  * Sparse checkout is meant to narrow down checkout area
1143                  * but it does not make sense to narrow down to empty working
1144                  * tree. This is usually a mistake in sparse checkout rules.
1145                  * Do not allow users to do that.
1146                  */
1147                 if (o->result.cache_nr && empty_worktree) {
1148                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1149                         goto done;
1150                 }
1151         }
1152
1153         o->src_index = NULL;
1154         ret = check_updates(o) ? (-2) : 0;
1155         if (o->dst_index) {
1156                 discard_index(o->dst_index);
1157                 *o->dst_index = o->result;
1158         }
1159
1160 done:
1161         clear_exclude_list(&el);
1162         return ret;
1163
1164 return_failed:
1165         if (o->show_all_errors)
1166                 display_error_msgs(o);
1167         mark_all_ce_unused(o->src_index);
1168         ret = unpack_failed(o, NULL);
1169         if (o->exiting_early)
1170                 ret = 0;
1171         goto done;
1172 }
1173
1174 /* Here come the merge functions */
1175
1176 static int reject_merge(const struct cache_entry *ce,
1177                         struct unpack_trees_options *o)
1178 {
1179         return o->gently ? -1 :
1180                 add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1181 }
1182
1183 static int same(const struct cache_entry *a, const struct cache_entry *b)
1184 {
1185         if (!!a != !!b)
1186                 return 0;
1187         if (!a && !b)
1188                 return 1;
1189         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1190                 return 0;
1191         return a->ce_mode == b->ce_mode &&
1192                !hashcmp(a->sha1, b->sha1);
1193 }
1194
1195
1196 /*
1197  * When a CE gets turned into an unmerged entry, we
1198  * want it to be up-to-date
1199  */
1200 static int verify_uptodate_1(const struct cache_entry *ce,
1201                              struct unpack_trees_options *o,
1202                              enum unpack_trees_error_types error_type)
1203 {
1204         struct stat st;
1205
1206         if (o->index_only)
1207                 return 0;
1208
1209         /*
1210          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1211          * if this entry is truly up-to-date because this file may be
1212          * overwritten.
1213          */
1214         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1215                 ; /* keep checking */
1216         else if (o->reset || ce_uptodate(ce))
1217                 return 0;
1218
1219         if (!lstat(ce->name, &st)) {
1220                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1221                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1222                 if (!changed)
1223                         return 0;
1224                 /*
1225                  * NEEDSWORK: the current default policy is to allow
1226                  * submodule to be out of sync wrt the superproject
1227                  * index.  This needs to be tightened later for
1228                  * submodules that are marked to be automatically
1229                  * checked out.
1230                  */
1231                 if (S_ISGITLINK(ce->ce_mode))
1232                         return 0;
1233                 errno = 0;
1234         }
1235         if (errno == ENOENT)
1236                 return 0;
1237         return o->gently ? -1 :
1238                 add_rejected_path(o, error_type, ce->name);
1239 }
1240
1241 static int verify_uptodate(const struct cache_entry *ce,
1242                            struct unpack_trees_options *o)
1243 {
1244         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1245                 return 0;
1246         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1247 }
1248
1249 static int verify_uptodate_sparse(const struct cache_entry *ce,
1250                                   struct unpack_trees_options *o)
1251 {
1252         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1253 }
1254
1255 static void invalidate_ce_path(const struct cache_entry *ce,
1256                                struct unpack_trees_options *o)
1257 {
1258         if (ce)
1259                 cache_tree_invalidate_path(o->src_index, ce->name);
1260 }
1261
1262 /*
1263  * Check that checking out ce->sha1 in subdir ce->name is not
1264  * going to overwrite any working files.
1265  *
1266  * Currently, git does not checkout subprojects during a superproject
1267  * checkout, so it is not going to overwrite anything.
1268  */
1269 static int verify_clean_submodule(const struct cache_entry *ce,
1270                                   enum unpack_trees_error_types error_type,
1271                                   struct unpack_trees_options *o)
1272 {
1273         return 0;
1274 }
1275
1276 static int verify_clean_subdirectory(const struct cache_entry *ce,
1277                                      enum unpack_trees_error_types error_type,
1278                                      struct unpack_trees_options *o)
1279 {
1280         /*
1281          * we are about to extract "ce->name"; we would not want to lose
1282          * anything in the existing directory there.
1283          */
1284         int namelen;
1285         int i;
1286         struct dir_struct d;
1287         char *pathbuf;
1288         int cnt = 0;
1289         unsigned char sha1[20];
1290
1291         if (S_ISGITLINK(ce->ce_mode) &&
1292             resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
1293                 /* If we are not going to update the submodule, then
1294                  * we don't care.
1295                  */
1296                 if (!hashcmp(sha1, ce->sha1))
1297                         return 0;
1298                 return verify_clean_submodule(ce, error_type, o);
1299         }
1300
1301         /*
1302          * First let's make sure we do not have a local modification
1303          * in that directory.
1304          */
1305         namelen = ce_namelen(ce);
1306         for (i = locate_in_src_index(ce, o);
1307              i < o->src_index->cache_nr;
1308              i++) {
1309                 struct cache_entry *ce2 = o->src_index->cache[i];
1310                 int len = ce_namelen(ce2);
1311                 if (len < namelen ||
1312                     strncmp(ce->name, ce2->name, namelen) ||
1313                     ce2->name[namelen] != '/')
1314                         break;
1315                 /*
1316                  * ce2->name is an entry in the subdirectory to be
1317                  * removed.
1318                  */
1319                 if (!ce_stage(ce2)) {
1320                         if (verify_uptodate(ce2, o))
1321                                 return -1;
1322                         add_entry(o, ce2, CE_REMOVE, 0);
1323                         mark_ce_used(ce2, o);
1324                 }
1325                 cnt++;
1326         }
1327
1328         /*
1329          * Then we need to make sure that we do not lose a locally
1330          * present file that is not ignored.
1331          */
1332         pathbuf = xmalloc(namelen + 2);
1333         memcpy(pathbuf, ce->name, namelen);
1334         strcpy(pathbuf+namelen, "/");
1335
1336         memset(&d, 0, sizeof(d));
1337         if (o->dir)
1338                 d.exclude_per_dir = o->dir->exclude_per_dir;
1339         i = read_directory(&d, pathbuf, namelen+1, NULL);
1340         if (i)
1341                 return o->gently ? -1 :
1342                         add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1343         free(pathbuf);
1344         return cnt;
1345 }
1346
1347 /*
1348  * This gets called when there was no index entry for the tree entry 'dst',
1349  * but we found a file in the working tree that 'lstat()' said was fine,
1350  * and we're on a case-insensitive filesystem.
1351  *
1352  * See if we can find a case-insensitive match in the index that also
1353  * matches the stat information, and assume it's that other file!
1354  */
1355 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1356 {
1357         const struct cache_entry *src;
1358
1359         src = index_file_exists(o->src_index, name, len, 1);
1360         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1361 }
1362
1363 static int check_ok_to_remove(const char *name, int len, int dtype,
1364                               const struct cache_entry *ce, struct stat *st,
1365                               enum unpack_trees_error_types error_type,
1366                               struct unpack_trees_options *o)
1367 {
1368         const struct cache_entry *result;
1369
1370         /*
1371          * It may be that the 'lstat()' succeeded even though
1372          * target 'ce' was absent, because there is an old
1373          * entry that is different only in case..
1374          *
1375          * Ignore that lstat() if it matches.
1376          */
1377         if (ignore_case && icase_exists(o, name, len, st))
1378                 return 0;
1379
1380         if (o->dir &&
1381             is_excluded(o->dir, name, &dtype))
1382                 /*
1383                  * ce->name is explicitly excluded, so it is Ok to
1384                  * overwrite it.
1385                  */
1386                 return 0;
1387         if (S_ISDIR(st->st_mode)) {
1388                 /*
1389                  * We are checking out path "foo" and
1390                  * found "foo/." in the working tree.
1391                  * This is tricky -- if we have modified
1392                  * files that are in "foo/" we would lose
1393                  * them.
1394                  */
1395                 if (verify_clean_subdirectory(ce, error_type, o) < 0)
1396                         return -1;
1397                 return 0;
1398         }
1399
1400         /*
1401          * The previous round may already have decided to
1402          * delete this path, which is in a subdirectory that
1403          * is being replaced with a blob.
1404          */
1405         result = index_file_exists(&o->result, name, len, 0);
1406         if (result) {
1407                 if (result->ce_flags & CE_REMOVE)
1408                         return 0;
1409         }
1410
1411         return o->gently ? -1 :
1412                 add_rejected_path(o, error_type, name);
1413 }
1414
1415 /*
1416  * We do not want to remove or overwrite a working tree file that
1417  * is not tracked, unless it is ignored.
1418  */
1419 static int verify_absent_1(const struct cache_entry *ce,
1420                            enum unpack_trees_error_types error_type,
1421                            struct unpack_trees_options *o)
1422 {
1423         int len;
1424         struct stat st;
1425
1426         if (o->index_only || o->reset || !o->update)
1427                 return 0;
1428
1429         len = check_leading_path(ce->name, ce_namelen(ce));
1430         if (!len)
1431                 return 0;
1432         else if (len > 0) {
1433                 char path[PATH_MAX + 1];
1434                 memcpy(path, ce->name, len);
1435                 path[len] = 0;
1436                 if (lstat(path, &st))
1437                         return error("cannot stat '%s': %s", path,
1438                                         strerror(errno));
1439
1440                 return check_ok_to_remove(path, len, DT_UNKNOWN, NULL, &st,
1441                                 error_type, o);
1442         } else if (lstat(ce->name, &st)) {
1443                 if (errno != ENOENT)
1444                         return error("cannot stat '%s': %s", ce->name,
1445                                      strerror(errno));
1446                 return 0;
1447         } else {
1448                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1449                                           ce_to_dtype(ce), ce, &st,
1450                                           error_type, o);
1451         }
1452 }
1453
1454 static int verify_absent(const struct cache_entry *ce,
1455                          enum unpack_trees_error_types error_type,
1456                          struct unpack_trees_options *o)
1457 {
1458         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1459                 return 0;
1460         return verify_absent_1(ce, error_type, o);
1461 }
1462
1463 static int verify_absent_sparse(const struct cache_entry *ce,
1464                                 enum unpack_trees_error_types error_type,
1465                                 struct unpack_trees_options *o)
1466 {
1467         enum unpack_trees_error_types orphaned_error = error_type;
1468         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1469                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1470
1471         return verify_absent_1(ce, orphaned_error, o);
1472 }
1473
1474 static int merged_entry(const struct cache_entry *ce,
1475                         const struct cache_entry *old,
1476                         struct unpack_trees_options *o)
1477 {
1478         int update = CE_UPDATE;
1479         struct cache_entry *merge = dup_entry(ce);
1480
1481         if (!old) {
1482                 /*
1483                  * New index entries. In sparse checkout, the following
1484                  * verify_absent() will be delayed until after
1485                  * traverse_trees() finishes in unpack_trees(), then:
1486                  *
1487                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1488                  *  - verify_absent() be called again, this time with
1489                  *    correct CE_NEW_SKIP_WORKTREE
1490                  *
1491                  * verify_absent() call here does nothing in sparse
1492                  * checkout (i.e. o->skip_sparse_checkout == 0)
1493                  */
1494                 update |= CE_ADDED;
1495                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1496
1497                 if (verify_absent(merge,
1498                                   ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1499                         free(merge);
1500                         return -1;
1501                 }
1502                 invalidate_ce_path(merge, o);
1503         } else if (!(old->ce_flags & CE_CONFLICTED)) {
1504                 /*
1505                  * See if we can re-use the old CE directly?
1506                  * That way we get the uptodate stat info.
1507                  *
1508                  * This also removes the UPDATE flag on a match; otherwise
1509                  * we will end up overwriting local changes in the work tree.
1510                  */
1511                 if (same(old, merge)) {
1512                         copy_cache_entry(merge, old);
1513                         update = 0;
1514                 } else {
1515                         if (verify_uptodate(old, o)) {
1516                                 free(merge);
1517                                 return -1;
1518                         }
1519                         /* Migrate old flags over */
1520                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1521                         invalidate_ce_path(old, o);
1522                 }
1523         } else {
1524                 /*
1525                  * Previously unmerged entry left as an existence
1526                  * marker by read_index_unmerged();
1527                  */
1528                 invalidate_ce_path(old, o);
1529         }
1530
1531         do_add_entry(o, merge, update, CE_STAGEMASK);
1532         return 1;
1533 }
1534
1535 static int deleted_entry(const struct cache_entry *ce,
1536                          const struct cache_entry *old,
1537                          struct unpack_trees_options *o)
1538 {
1539         /* Did it exist in the index? */
1540         if (!old) {
1541                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1542                         return -1;
1543                 return 0;
1544         }
1545         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1546                 return -1;
1547         add_entry(o, ce, CE_REMOVE, 0);
1548         invalidate_ce_path(ce, o);
1549         return 1;
1550 }
1551
1552 static int keep_entry(const struct cache_entry *ce,
1553                       struct unpack_trees_options *o)
1554 {
1555         add_entry(o, ce, 0, 0);
1556         return 1;
1557 }
1558
1559 #if DBRT_DEBUG
1560 static void show_stage_entry(FILE *o,
1561                              const char *label, const struct cache_entry *ce)
1562 {
1563         if (!ce)
1564                 fprintf(o, "%s (missing)\n", label);
1565         else
1566                 fprintf(o, "%s%06o %s %d\t%s\n",
1567                         label,
1568                         ce->ce_mode,
1569                         sha1_to_hex(ce->sha1),
1570                         ce_stage(ce),
1571                         ce->name);
1572 }
1573 #endif
1574
1575 int threeway_merge(const struct cache_entry * const *stages,
1576                    struct unpack_trees_options *o)
1577 {
1578         const struct cache_entry *index;
1579         const struct cache_entry *head;
1580         const struct cache_entry *remote = stages[o->head_idx + 1];
1581         int count;
1582         int head_match = 0;
1583         int remote_match = 0;
1584
1585         int df_conflict_head = 0;
1586         int df_conflict_remote = 0;
1587
1588         int any_anc_missing = 0;
1589         int no_anc_exists = 1;
1590         int i;
1591
1592         for (i = 1; i < o->head_idx; i++) {
1593                 if (!stages[i] || stages[i] == o->df_conflict_entry)
1594                         any_anc_missing = 1;
1595                 else
1596                         no_anc_exists = 0;
1597         }
1598
1599         index = stages[0];
1600         head = stages[o->head_idx];
1601
1602         if (head == o->df_conflict_entry) {
1603                 df_conflict_head = 1;
1604                 head = NULL;
1605         }
1606
1607         if (remote == o->df_conflict_entry) {
1608                 df_conflict_remote = 1;
1609                 remote = NULL;
1610         }
1611
1612         /*
1613          * First, if there's a #16 situation, note that to prevent #13
1614          * and #14.
1615          */
1616         if (!same(remote, head)) {
1617                 for (i = 1; i < o->head_idx; i++) {
1618                         if (same(stages[i], head)) {
1619                                 head_match = i;
1620                         }
1621                         if (same(stages[i], remote)) {
1622                                 remote_match = i;
1623                         }
1624                 }
1625         }
1626
1627         /*
1628          * We start with cases where the index is allowed to match
1629          * something other than the head: #14(ALT) and #2ALT, where it
1630          * is permitted to match the result instead.
1631          */
1632         /* #14, #14ALT, #2ALT */
1633         if (remote && !df_conflict_head && head_match && !remote_match) {
1634                 if (index && !same(index, remote) && !same(index, head))
1635                         return reject_merge(index, o);
1636                 return merged_entry(remote, index, o);
1637         }
1638         /*
1639          * If we have an entry in the index cache, then we want to
1640          * make sure that it matches head.
1641          */
1642         if (index && !same(index, head))
1643                 return reject_merge(index, o);
1644
1645         if (head) {
1646                 /* #5ALT, #15 */
1647                 if (same(head, remote))
1648                         return merged_entry(head, index, o);
1649                 /* #13, #3ALT */
1650                 if (!df_conflict_remote && remote_match && !head_match)
1651                         return merged_entry(head, index, o);
1652         }
1653
1654         /* #1 */
1655         if (!head && !remote && any_anc_missing)
1656                 return 0;
1657
1658         /*
1659          * Under the "aggressive" rule, we resolve mostly trivial
1660          * cases that we historically had git-merge-one-file resolve.
1661          */
1662         if (o->aggressive) {
1663                 int head_deleted = !head;
1664                 int remote_deleted = !remote;
1665                 const struct cache_entry *ce = NULL;
1666
1667                 if (index)
1668                         ce = index;
1669                 else if (head)
1670                         ce = head;
1671                 else if (remote)
1672                         ce = remote;
1673                 else {
1674                         for (i = 1; i < o->head_idx; i++) {
1675                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
1676                                         ce = stages[i];
1677                                         break;
1678                                 }
1679                         }
1680                 }
1681
1682                 /*
1683                  * Deleted in both.
1684                  * Deleted in one and unchanged in the other.
1685                  */
1686                 if ((head_deleted && remote_deleted) ||
1687                     (head_deleted && remote && remote_match) ||
1688                     (remote_deleted && head && head_match)) {
1689                         if (index)
1690                                 return deleted_entry(index, index, o);
1691                         if (ce && !head_deleted) {
1692                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1693                                         return -1;
1694                         }
1695                         return 0;
1696                 }
1697                 /*
1698                  * Added in both, identically.
1699                  */
1700                 if (no_anc_exists && head && remote && same(head, remote))
1701                         return merged_entry(head, index, o);
1702
1703         }
1704
1705         /* Below are "no merge" cases, which require that the index be
1706          * up-to-date to avoid the files getting overwritten with
1707          * conflict resolution files.
1708          */
1709         if (index) {
1710                 if (verify_uptodate(index, o))
1711                         return -1;
1712         }
1713
1714         o->nontrivial_merge = 1;
1715
1716         /* #2, #3, #4, #6, #7, #9, #10, #11. */
1717         count = 0;
1718         if (!head_match || !remote_match) {
1719                 for (i = 1; i < o->head_idx; i++) {
1720                         if (stages[i] && stages[i] != o->df_conflict_entry) {
1721                                 keep_entry(stages[i], o);
1722                                 count++;
1723                                 break;
1724                         }
1725                 }
1726         }
1727 #if DBRT_DEBUG
1728         else {
1729                 fprintf(stderr, "read-tree: warning #16 detected\n");
1730                 show_stage_entry(stderr, "head   ", stages[head_match]);
1731                 show_stage_entry(stderr, "remote ", stages[remote_match]);
1732         }
1733 #endif
1734         if (head) { count += keep_entry(head, o); }
1735         if (remote) { count += keep_entry(remote, o); }
1736         return count;
1737 }
1738
1739 /*
1740  * Two-way merge.
1741  *
1742  * The rule is to "carry forward" what is in the index without losing
1743  * information across a "fast-forward", favoring a successful merge
1744  * over a merge failure when it makes sense.  For details of the
1745  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
1746  *
1747  */
1748 int twoway_merge(const struct cache_entry * const *src,
1749                  struct unpack_trees_options *o)
1750 {
1751         const struct cache_entry *current = src[0];
1752         const struct cache_entry *oldtree = src[1];
1753         const struct cache_entry *newtree = src[2];
1754
1755         if (o->merge_size != 2)
1756                 return error("Cannot do a twoway merge of %d trees",
1757                              o->merge_size);
1758
1759         if (oldtree == o->df_conflict_entry)
1760                 oldtree = NULL;
1761         if (newtree == o->df_conflict_entry)
1762                 newtree = NULL;
1763
1764         if (current) {
1765                 if (current->ce_flags & CE_CONFLICTED) {
1766                         if (same(oldtree, newtree) || o->reset) {
1767                                 if (!newtree)
1768                                         return deleted_entry(current, current, o);
1769                                 else
1770                                         return merged_entry(newtree, current, o);
1771                         }
1772                         return reject_merge(current, o);
1773                 } else if ((!oldtree && !newtree) || /* 4 and 5 */
1774                          (!oldtree && newtree &&
1775                           same(current, newtree)) || /* 6 and 7 */
1776                          (oldtree && newtree &&
1777                           same(oldtree, newtree)) || /* 14 and 15 */
1778                          (oldtree && newtree &&
1779                           !same(oldtree, newtree) && /* 18 and 19 */
1780                           same(current, newtree))) {
1781                         return keep_entry(current, o);
1782                 } else if (oldtree && !newtree && same(current, oldtree)) {
1783                         /* 10 or 11 */
1784                         return deleted_entry(oldtree, current, o);
1785                 } else if (oldtree && newtree &&
1786                          same(current, oldtree) && !same(current, newtree)) {
1787                         /* 20 or 21 */
1788                         return merged_entry(newtree, current, o);
1789                 } else
1790                         return reject_merge(current, o);
1791         }
1792         else if (newtree) {
1793                 if (oldtree && !o->initial_checkout) {
1794                         /*
1795                          * deletion of the path was staged;
1796                          */
1797                         if (same(oldtree, newtree))
1798                                 return 1;
1799                         return reject_merge(oldtree, o);
1800                 }
1801                 return merged_entry(newtree, current, o);
1802         }
1803         return deleted_entry(oldtree, current, o);
1804 }
1805
1806 /*
1807  * Bind merge.
1808  *
1809  * Keep the index entries at stage0, collapse stage1 but make sure
1810  * stage0 does not have anything there.
1811  */
1812 int bind_merge(const struct cache_entry * const *src,
1813                struct unpack_trees_options *o)
1814 {
1815         const struct cache_entry *old = src[0];
1816         const struct cache_entry *a = src[1];
1817
1818         if (o->merge_size != 1)
1819                 return error("Cannot do a bind merge of %d trees",
1820                              o->merge_size);
1821         if (a && old)
1822                 return o->gently ? -1 :
1823                         error(ERRORMSG(o, ERROR_BIND_OVERLAP), a->name, old->name);
1824         if (!a)
1825                 return keep_entry(old, o);
1826         else
1827                 return merged_entry(a, NULL, o);
1828 }
1829
1830 /*
1831  * One-way merge.
1832  *
1833  * The rule is:
1834  * - take the stat information from stage0, take the data from stage1
1835  */
1836 int oneway_merge(const struct cache_entry * const *src,
1837                  struct unpack_trees_options *o)
1838 {
1839         const struct cache_entry *old = src[0];
1840         const struct cache_entry *a = src[1];
1841
1842         if (o->merge_size != 1)
1843                 return error("Cannot do a oneway merge of %d trees",
1844                              o->merge_size);
1845
1846         if (!a || a == o->df_conflict_entry)
1847                 return deleted_entry(old, old, o);
1848
1849         if (old && same(old, a)) {
1850                 int update = 0;
1851                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
1852                         struct stat st;
1853                         if (lstat(old->name, &st) ||
1854                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
1855                                 update |= CE_UPDATE;
1856                 }
1857                 add_entry(o, old, update, 0);
1858                 return 0;
1859         }
1860         return merged_entry(a, old, o);
1861 }