Code

verify_uptodate(): add ce_uptodate(ce) test
[git.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"
11 /*
12  * Error messages expected by scripts out of plumbing commands such as
13  * read-tree.  Non-scripted Porcelain is not required to use these messages
14  * and in fact are encouraged to reword them to better suit their particular
15  * situation better.  See how "git checkout" replaces not_uptodate_file to
16  * explain why it does not allow switching between branches when you have
17  * local changes, for example.
18  */
19 static struct unpack_trees_error_msgs unpack_plumbing_errors = {
20         /* would_overwrite */
21         "Entry '%s' would be overwritten by merge. Cannot merge.",
23         /* not_uptodate_file */
24         "Entry '%s' not uptodate. Cannot merge.",
26         /* not_uptodate_dir */
27         "Updating '%s' would lose untracked files in it",
29         /* would_lose_untracked */
30         "Untracked working tree file '%s' would be %s by merge.",
32         /* bind_overlap */
33         "Entry '%s' overlaps with '%s'.  Cannot bind.",
34 };
36 #define ERRORMSG(o,fld) \
37         ( ((o) && (o)->msgs.fld) \
38         ? ((o)->msgs.fld) \
39         : (unpack_plumbing_errors.fld) )
41 static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
42         unsigned int set, unsigned int clear)
43 {
44         unsigned int size = ce_size(ce);
45         struct cache_entry *new = xmalloc(size);
47         clear |= CE_HASHED | CE_UNHASHED;
49         memcpy(new, ce, size);
50         new->next = NULL;
51         new->ce_flags = (new->ce_flags & ~clear) | set;
52         add_index_entry(&o->result, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE|ADD_CACHE_SKIP_DFCHECK);
53 }
55 /*
56  * Unlink the last component and schedule the leading directories for
57  * removal, such that empty directories get removed.
58  */
59 static void unlink_entry(struct cache_entry *ce)
60 {
61         if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
62                 return;
63         if (unlink(ce->name))
64                 return;
65         schedule_dir_for_removal(ce->name, ce_namelen(ce));
66 }
68 static struct checkout state;
69 static int check_updates(struct unpack_trees_options *o)
70 {
71         unsigned cnt = 0, total = 0;
72         struct progress *progress = NULL;
73         struct index_state *index = &o->result;
74         int i;
75         int errs = 0;
77         if (o->update && o->verbose_update) {
78                 for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
79                         struct cache_entry *ce = index->cache[cnt];
80                         if (ce->ce_flags & (CE_UPDATE | CE_REMOVE))
81                                 total++;
82                 }
84                 progress = start_progress_delay("Checking out files",
85                                                 total, 50, 1);
86                 cnt = 0;
87         }
89         for (i = 0; i < index->cache_nr; i++) {
90                 struct cache_entry *ce = index->cache[i];
92                 if (ce->ce_flags & CE_REMOVE) {
93                         display_progress(progress, ++cnt);
94                         if (o->update)
95                                 unlink_entry(ce);
96                 }
97         }
98         remove_marked_cache_entries(&o->result);
99         remove_scheduled_dirs();
101         for (i = 0; i < index->cache_nr; i++) {
102                 struct cache_entry *ce = index->cache[i];
104                 if (ce->ce_flags & CE_UPDATE) {
105                         display_progress(progress, ++cnt);
106                         ce->ce_flags &= ~CE_UPDATE;
107                         if (o->update) {
108                                 errs |= checkout_entry(ce, &state, NULL);
109                         }
110                 }
111         }
112         stop_progress(&progress);
113         return errs != 0;
116 static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
118         int ret = o->fn(src, o);
119         if (ret > 0)
120                 ret = 0;
121         return ret;
124 static int unpack_index_entry(struct cache_entry *ce, struct unpack_trees_options *o)
126         struct cache_entry *src[5] = { ce, };
128         o->pos++;
129         if (ce_stage(ce)) {
130                 if (o->skip_unmerged) {
131                         add_entry(o, ce, 0, 0);
132                         return 0;
133                 }
134         }
135         return call_unpack_fn(src, o);
138 int traverse_trees_recursive(int n, unsigned long dirmask, unsigned long df_conflicts, struct name_entry *names, struct traverse_info *info)
140         int i;
141         struct tree_desc t[MAX_UNPACK_TREES];
142         struct traverse_info newinfo;
143         struct name_entry *p;
145         p = names;
146         while (!p->mode)
147                 p++;
149         newinfo = *info;
150         newinfo.prev = info;
151         newinfo.name = *p;
152         newinfo.pathlen += tree_entry_len(p->path, p->sha1) + 1;
153         newinfo.conflicts |= df_conflicts;
155         for (i = 0; i < n; i++, dirmask >>= 1) {
156                 const unsigned char *sha1 = NULL;
157                 if (dirmask & 1)
158                         sha1 = names[i].sha1;
159                 fill_tree_descriptor(t+i, sha1);
160         }
161         return traverse_trees(n, t, &newinfo);
164 /*
165  * Compare the traverse-path to the cache entry without actually
166  * having to generate the textual representation of the traverse
167  * path.
168  *
169  * NOTE! This *only* compares up to the size of the traverse path
170  * itself - the caller needs to do the final check for the cache
171  * entry having more data at the end!
172  */
173 static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
175         int len, pathlen, ce_len;
176         const char *ce_name;
178         if (info->prev) {
179                 int cmp = do_compare_entry(ce, info->prev, &info->name);
180                 if (cmp)
181                         return cmp;
182         }
183         pathlen = info->pathlen;
184         ce_len = ce_namelen(ce);
186         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
187         if (ce_len < pathlen)
188                 return -1;
190         ce_len -= pathlen;
191         ce_name = ce->name + pathlen;
193         len = tree_entry_len(n->path, n->sha1);
194         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
197 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
199         int cmp = do_compare_entry(ce, info, n);
200         if (cmp)
201                 return cmp;
203         /*
204          * Even if the beginning compared identically, the ce should
205          * compare as bigger than a directory leading up to it!
206          */
207         return ce_namelen(ce) > traverse_path_len(info, n);
210 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
212         int len = traverse_path_len(info, n);
213         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
215         ce->ce_mode = create_ce_mode(n->mode);
216         ce->ce_flags = create_ce_flags(len, stage);
217         hashcpy(ce->sha1, n->sha1);
218         make_traverse_path(ce->name, info, n);
220         return ce;
223 static int unpack_nondirectories(int n, unsigned long mask,
224                                  unsigned long dirmask,
225                                  struct cache_entry **src,
226                                  const struct name_entry *names,
227                                  const struct traverse_info *info)
229         int i;
230         struct unpack_trees_options *o = info->data;
231         unsigned long conflicts;
233         /* Do we have *only* directories? Nothing to do */
234         if (mask == dirmask && !src[0])
235                 return 0;
237         conflicts = info->conflicts;
238         if (o->merge)
239                 conflicts >>= 1;
240         conflicts |= dirmask;
242         /*
243          * Ok, we've filled in up to any potential index entry in src[0],
244          * now do the rest.
245          */
246         for (i = 0; i < n; i++) {
247                 int stage;
248                 unsigned int bit = 1ul << i;
249                 if (conflicts & bit) {
250                         src[i + o->merge] = o->df_conflict_entry;
251                         continue;
252                 }
253                 if (!(mask & bit))
254                         continue;
255                 if (!o->merge)
256                         stage = 0;
257                 else if (i + 1 < o->head_idx)
258                         stage = 1;
259                 else if (i + 1 > o->head_idx)
260                         stage = 3;
261                 else
262                         stage = 2;
263                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
264         }
266         if (o->merge)
267                 return call_unpack_fn(src, o);
269         n += o->merge;
270         for (i = 0; i < n; i++)
271                 add_entry(o, src[i], 0, 0);
272         return 0;
275 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
277         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
278         struct unpack_trees_options *o = info->data;
279         const struct name_entry *p = names;
281         /* Find first entry with a real name (we could use "mask" too) */
282         while (!p->mode)
283                 p++;
285         /* Are we supposed to look at the index too? */
286         if (o->merge) {
287                 while (o->pos < o->src_index->cache_nr) {
288                         struct cache_entry *ce = o->src_index->cache[o->pos];
289                         int cmp = compare_entry(ce, info, p);
290                         if (cmp < 0) {
291                                 if (unpack_index_entry(ce, o) < 0)
292                                         return -1;
293                                 continue;
294                         }
295                         if (!cmp) {
296                                 o->pos++;
297                                 if (ce_stage(ce)) {
298                                         /*
299                                          * If we skip unmerged index entries, we'll skip this
300                                          * entry *and* the tree entries associated with it!
301                                          */
302                                         if (o->skip_unmerged) {
303                                                 add_entry(o, ce, 0, 0);
304                                                 return mask;
305                                         }
306                                 }
307                                 src[0] = ce;
308                         }
309                         break;
310                 }
311         }
313         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
314                 return -1;
316         /* Now handle any directories.. */
317         if (dirmask) {
318                 unsigned long conflicts = mask & ~dirmask;
319                 if (o->merge) {
320                         conflicts <<= 1;
321                         if (src[0])
322                                 conflicts |= 1;
323                 }
324                 if (traverse_trees_recursive(n, dirmask, conflicts,
325                                              names, info) < 0)
326                         return -1;
327                 return mask;
328         }
330         return mask;
333 static int unpack_failed(struct unpack_trees_options *o, const char *message)
335         discard_index(&o->result);
336         if (!o->gently) {
337                 if (message)
338                         return error("%s", message);
339                 return -1;
340         }
341         return -1;
344 /*
345  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
346  * resulting index, -2 on failure to reflect the changes to the work tree.
347  */
348 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
350         int ret;
351         static struct cache_entry *dfc;
353         if (len > MAX_UNPACK_TREES)
354                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
355         memset(&state, 0, sizeof(state));
356         state.base_dir = "";
357         state.force = 1;
358         state.quiet = 1;
359         state.refresh_cache = 1;
361         memset(&o->result, 0, sizeof(o->result));
362         o->result.initialized = 1;
363         if (o->src_index) {
364                 o->result.timestamp.sec = o->src_index->timestamp.sec;
365 #ifdef USE_NSEC
366                 o->result.timestamp.nsec = o->src_index->timestamp.nsec;
367 #endif
368         }
369         o->merge_size = len;
371         if (!dfc)
372                 dfc = xcalloc(1, cache_entry_size(0));
373         o->df_conflict_entry = dfc;
375         if (len) {
376                 const char *prefix = o->prefix ? o->prefix : "";
377                 struct traverse_info info;
379                 setup_traverse_info(&info, prefix);
380                 info.fn = unpack_callback;
381                 info.data = o;
383                 if (traverse_trees(len, t, &info) < 0)
384                         return unpack_failed(o, NULL);
385         }
387         /* Any left-over entries in the index? */
388         if (o->merge) {
389                 while (o->pos < o->src_index->cache_nr) {
390                         struct cache_entry *ce = o->src_index->cache[o->pos];
391                         if (unpack_index_entry(ce, o) < 0)
392                                 return unpack_failed(o, NULL);
393                 }
394         }
396         if (o->trivial_merges_only && o->nontrivial_merge)
397                 return unpack_failed(o, "Merge requires file-level merging");
399         o->src_index = NULL;
400         ret = check_updates(o) ? (-2) : 0;
401         if (o->dst_index)
402                 *o->dst_index = o->result;
403         return ret;
406 /* Here come the merge functions */
408 static int reject_merge(struct cache_entry *ce, struct unpack_trees_options *o)
410         return error(ERRORMSG(o, would_overwrite), ce->name);
413 static int same(struct cache_entry *a, struct cache_entry *b)
415         if (!!a != !!b)
416                 return 0;
417         if (!a && !b)
418                 return 1;
419         return a->ce_mode == b->ce_mode &&
420                !hashcmp(a->sha1, b->sha1);
424 /*
425  * When a CE gets turned into an unmerged entry, we
426  * want it to be up-to-date
427  */
428 static int verify_uptodate(struct cache_entry *ce,
429                 struct unpack_trees_options *o)
431         struct stat st;
433         if (o->index_only || o->reset || ce_uptodate(ce))
434                 return 0;
436         if (!lstat(ce->name, &st)) {
437                 unsigned changed = ie_match_stat(o->src_index, ce, &st, CE_MATCH_IGNORE_VALID);
438                 if (!changed)
439                         return 0;
440                 /*
441                  * NEEDSWORK: the current default policy is to allow
442                  * submodule to be out of sync wrt the supermodule
443                  * index.  This needs to be tightened later for
444                  * submodules that are marked to be automatically
445                  * checked out.
446                  */
447                 if (S_ISGITLINK(ce->ce_mode))
448                         return 0;
449                 errno = 0;
450         }
451         if (errno == ENOENT)
452                 return 0;
453         return o->gently ? -1 :
454                 error(ERRORMSG(o, not_uptodate_file), ce->name);
457 static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
459         if (ce)
460                 cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
463 /*
464  * Check that checking out ce->sha1 in subdir ce->name is not
465  * going to overwrite any working files.
466  *
467  * Currently, git does not checkout subprojects during a superproject
468  * checkout, so it is not going to overwrite anything.
469  */
470 static int verify_clean_submodule(struct cache_entry *ce, const char *action,
471                                       struct unpack_trees_options *o)
473         return 0;
476 static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
477                                       struct unpack_trees_options *o)
479         /*
480          * we are about to extract "ce->name"; we would not want to lose
481          * anything in the existing directory there.
482          */
483         int namelen;
484         int i;
485         struct dir_struct d;
486         char *pathbuf;
487         int cnt = 0;
488         unsigned char sha1[20];
490         if (S_ISGITLINK(ce->ce_mode) &&
491             resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
492                 /* If we are not going to update the submodule, then
493                  * we don't care.
494                  */
495                 if (!hashcmp(sha1, ce->sha1))
496                         return 0;
497                 return verify_clean_submodule(ce, action, o);
498         }
500         /*
501          * First let's make sure we do not have a local modification
502          * in that directory.
503          */
504         namelen = strlen(ce->name);
505         for (i = o->pos; i < o->src_index->cache_nr; i++) {
506                 struct cache_entry *ce2 = o->src_index->cache[i];
507                 int len = ce_namelen(ce2);
508                 if (len < namelen ||
509                     strncmp(ce->name, ce2->name, namelen) ||
510                     ce2->name[namelen] != '/')
511                         break;
512                 /*
513                  * ce2->name is an entry in the subdirectory.
514                  */
515                 if (!ce_stage(ce2)) {
516                         if (verify_uptodate(ce2, o))
517                                 return -1;
518                         add_entry(o, ce2, CE_REMOVE, 0);
519                 }
520                 cnt++;
521         }
523         /*
524          * Then we need to make sure that we do not lose a locally
525          * present file that is not ignored.
526          */
527         pathbuf = xmalloc(namelen + 2);
528         memcpy(pathbuf, ce->name, namelen);
529         strcpy(pathbuf+namelen, "/");
531         memset(&d, 0, sizeof(d));
532         if (o->dir)
533                 d.exclude_per_dir = o->dir->exclude_per_dir;
534         i = read_directory(&d, ce->name, pathbuf, namelen+1, NULL);
535         if (i)
536                 return o->gently ? -1 :
537                         error(ERRORMSG(o, not_uptodate_dir), ce->name);
538         free(pathbuf);
539         return cnt;
542 /*
543  * This gets called when there was no index entry for the tree entry 'dst',
544  * but we found a file in the working tree that 'lstat()' said was fine,
545  * and we're on a case-insensitive filesystem.
546  *
547  * See if we can find a case-insensitive match in the index that also
548  * matches the stat information, and assume it's that other file!
549  */
550 static int icase_exists(struct unpack_trees_options *o, struct cache_entry *dst, struct stat *st)
552         struct cache_entry *src;
554         src = index_name_exists(o->src_index, dst->name, ce_namelen(dst), 1);
555         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID);
558 /*
559  * We do not want to remove or overwrite a working tree file that
560  * is not tracked, unless it is ignored.
561  */
562 static int verify_absent(struct cache_entry *ce, const char *action,
563                          struct unpack_trees_options *o)
565         struct stat st;
567         if (o->index_only || o->reset || !o->update)
568                 return 0;
570         if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
571                 return 0;
573         if (!lstat(ce->name, &st)) {
574                 int ret;
575                 int dtype = ce_to_dtype(ce);
576                 struct cache_entry *result;
578                 /*
579                  * It may be that the 'lstat()' succeeded even though
580                  * target 'ce' was absent, because there is an old
581                  * entry that is different only in case..
582                  *
583                  * Ignore that lstat() if it matches.
584                  */
585                 if (ignore_case && icase_exists(o, ce, &st))
586                         return 0;
588                 if (o->dir && excluded(o->dir, ce->name, &dtype))
589                         /*
590                          * ce->name is explicitly excluded, so it is Ok to
591                          * overwrite it.
592                          */
593                         return 0;
594                 if (S_ISDIR(st.st_mode)) {
595                         /*
596                          * We are checking out path "foo" and
597                          * found "foo/." in the working tree.
598                          * This is tricky -- if we have modified
599                          * files that are in "foo/" we would lose
600                          * it.
601                          */
602                         ret = verify_clean_subdirectory(ce, action, o);
603                         if (ret < 0)
604                                 return ret;
606                         /*
607                          * If this removed entries from the index,
608                          * what that means is:
609                          *
610                          * (1) the caller unpack_callback() saw path/foo
611                          * in the index, and it has not removed it because
612                          * it thinks it is handling 'path' as blob with
613                          * D/F conflict;
614                          * (2) we will return "ok, we placed a merged entry
615                          * in the index" which would cause o->pos to be
616                          * incremented by one;
617                          * (3) however, original o->pos now has 'path/foo'
618                          * marked with "to be removed".
619                          *
620                          * We need to increment it by the number of
621                          * deleted entries here.
622                          */
623                         o->pos += ret;
624                         return 0;
625                 }
627                 /*
628                  * The previous round may already have decided to
629                  * delete this path, which is in a subdirectory that
630                  * is being replaced with a blob.
631                  */
632                 result = index_name_exists(&o->result, ce->name, ce_namelen(ce), 0);
633                 if (result) {
634                         if (result->ce_flags & CE_REMOVE)
635                                 return 0;
636                 }
638                 return o->gently ? -1 :
639                         error(ERRORMSG(o, would_lose_untracked), ce->name, action);
640         }
641         return 0;
644 static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
645                 struct unpack_trees_options *o)
647         int update = CE_UPDATE;
649         if (old) {
650                 /*
651                  * See if we can re-use the old CE directly?
652                  * That way we get the uptodate stat info.
653                  *
654                  * This also removes the UPDATE flag on a match; otherwise
655                  * we will end up overwriting local changes in the work tree.
656                  */
657                 if (same(old, merge)) {
658                         copy_cache_entry(merge, old);
659                         update = 0;
660                 } else {
661                         if (verify_uptodate(old, o))
662                                 return -1;
663                         invalidate_ce_path(old, o);
664                 }
665         }
666         else {
667                 if (verify_absent(merge, "overwritten", o))
668                         return -1;
669                 invalidate_ce_path(merge, o);
670         }
672         add_entry(o, merge, update, CE_STAGEMASK);
673         return 1;
676 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
677                 struct unpack_trees_options *o)
679         /* Did it exist in the index? */
680         if (!old) {
681                 if (verify_absent(ce, "removed", o))
682                         return -1;
683                 return 0;
684         }
685         if (verify_uptodate(old, o))
686                 return -1;
687         add_entry(o, ce, CE_REMOVE, 0);
688         invalidate_ce_path(ce, o);
689         return 1;
692 static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
694         add_entry(o, ce, 0, 0);
695         return 1;
698 #if DBRT_DEBUG
699 static void show_stage_entry(FILE *o,
700                              const char *label, const struct cache_entry *ce)
702         if (!ce)
703                 fprintf(o, "%s (missing)\n", label);
704         else
705                 fprintf(o, "%s%06o %s %d\t%s\n",
706                         label,
707                         ce->ce_mode,
708                         sha1_to_hex(ce->sha1),
709                         ce_stage(ce),
710                         ce->name);
712 #endif
714 int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
716         struct cache_entry *index;
717         struct cache_entry *head;
718         struct cache_entry *remote = stages[o->head_idx + 1];
719         int count;
720         int head_match = 0;
721         int remote_match = 0;
723         int df_conflict_head = 0;
724         int df_conflict_remote = 0;
726         int any_anc_missing = 0;
727         int no_anc_exists = 1;
728         int i;
730         for (i = 1; i < o->head_idx; i++) {
731                 if (!stages[i] || stages[i] == o->df_conflict_entry)
732                         any_anc_missing = 1;
733                 else
734                         no_anc_exists = 0;
735         }
737         index = stages[0];
738         head = stages[o->head_idx];
740         if (head == o->df_conflict_entry) {
741                 df_conflict_head = 1;
742                 head = NULL;
743         }
745         if (remote == o->df_conflict_entry) {
746                 df_conflict_remote = 1;
747                 remote = NULL;
748         }
750         /* First, if there's a #16 situation, note that to prevent #13
751          * and #14.
752          */
753         if (!same(remote, head)) {
754                 for (i = 1; i < o->head_idx; i++) {
755                         if (same(stages[i], head)) {
756                                 head_match = i;
757                         }
758                         if (same(stages[i], remote)) {
759                                 remote_match = i;
760                         }
761                 }
762         }
764         /* We start with cases where the index is allowed to match
765          * something other than the head: #14(ALT) and #2ALT, where it
766          * is permitted to match the result instead.
767          */
768         /* #14, #14ALT, #2ALT */
769         if (remote && !df_conflict_head && head_match && !remote_match) {
770                 if (index && !same(index, remote) && !same(index, head))
771                         return o->gently ? -1 : reject_merge(index, o);
772                 return merged_entry(remote, index, o);
773         }
774         /*
775          * If we have an entry in the index cache, then we want to
776          * make sure that it matches head.
777          */
778         if (index && !same(index, head))
779                 return o->gently ? -1 : reject_merge(index, o);
781         if (head) {
782                 /* #5ALT, #15 */
783                 if (same(head, remote))
784                         return merged_entry(head, index, o);
785                 /* #13, #3ALT */
786                 if (!df_conflict_remote && remote_match && !head_match)
787                         return merged_entry(head, index, o);
788         }
790         /* #1 */
791         if (!head && !remote && any_anc_missing)
792                 return 0;
794         /* Under the new "aggressive" rule, we resolve mostly trivial
795          * cases that we historically had git-merge-one-file resolve.
796          */
797         if (o->aggressive) {
798                 int head_deleted = !head && !df_conflict_head;
799                 int remote_deleted = !remote && !df_conflict_remote;
800                 struct cache_entry *ce = NULL;
802                 if (index)
803                         ce = index;
804                 else if (head)
805                         ce = head;
806                 else if (remote)
807                         ce = remote;
808                 else {
809                         for (i = 1; i < o->head_idx; i++) {
810                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
811                                         ce = stages[i];
812                                         break;
813                                 }
814                         }
815                 }
817                 /*
818                  * Deleted in both.
819                  * Deleted in one and unchanged in the other.
820                  */
821                 if ((head_deleted && remote_deleted) ||
822                     (head_deleted && remote && remote_match) ||
823                     (remote_deleted && head && head_match)) {
824                         if (index)
825                                 return deleted_entry(index, index, o);
826                         if (ce && !head_deleted) {
827                                 if (verify_absent(ce, "removed", o))
828                                         return -1;
829                         }
830                         return 0;
831                 }
832                 /*
833                  * Added in both, identically.
834                  */
835                 if (no_anc_exists && head && remote && same(head, remote))
836                         return merged_entry(head, index, o);
838         }
840         /* Below are "no merge" cases, which require that the index be
841          * up-to-date to avoid the files getting overwritten with
842          * conflict resolution files.
843          */
844         if (index) {
845                 if (verify_uptodate(index, o))
846                         return -1;
847         }
849         o->nontrivial_merge = 1;
851         /* #2, #3, #4, #6, #7, #9, #10, #11. */
852         count = 0;
853         if (!head_match || !remote_match) {
854                 for (i = 1; i < o->head_idx; i++) {
855                         if (stages[i] && stages[i] != o->df_conflict_entry) {
856                                 keep_entry(stages[i], o);
857                                 count++;
858                                 break;
859                         }
860                 }
861         }
862 #if DBRT_DEBUG
863         else {
864                 fprintf(stderr, "read-tree: warning #16 detected\n");
865                 show_stage_entry(stderr, "head   ", stages[head_match]);
866                 show_stage_entry(stderr, "remote ", stages[remote_match]);
867         }
868 #endif
869         if (head) { count += keep_entry(head, o); }
870         if (remote) { count += keep_entry(remote, o); }
871         return count;
874 /*
875  * Two-way merge.
876  *
877  * The rule is to "carry forward" what is in the index without losing
878  * information across a "fast forward", favoring a successful merge
879  * over a merge failure when it makes sense.  For details of the
880  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
881  *
882  */
883 int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
885         struct cache_entry *current = src[0];
886         struct cache_entry *oldtree = src[1];
887         struct cache_entry *newtree = src[2];
889         if (o->merge_size != 2)
890                 return error("Cannot do a twoway merge of %d trees",
891                              o->merge_size);
893         if (oldtree == o->df_conflict_entry)
894                 oldtree = NULL;
895         if (newtree == o->df_conflict_entry)
896                 newtree = NULL;
898         if (current) {
899                 if ((!oldtree && !newtree) || /* 4 and 5 */
900                     (!oldtree && newtree &&
901                      same(current, newtree)) || /* 6 and 7 */
902                     (oldtree && newtree &&
903                      same(oldtree, newtree)) || /* 14 and 15 */
904                     (oldtree && newtree &&
905                      !same(oldtree, newtree) && /* 18 and 19 */
906                      same(current, newtree))) {
907                         return keep_entry(current, o);
908                 }
909                 else if (oldtree && !newtree && same(current, oldtree)) {
910                         /* 10 or 11 */
911                         return deleted_entry(oldtree, current, o);
912                 }
913                 else if (oldtree && newtree &&
914                          same(current, oldtree) && !same(current, newtree)) {
915                         /* 20 or 21 */
916                         return merged_entry(newtree, current, o);
917                 }
918                 else {
919                         /* all other failures */
920                         if (oldtree)
921                                 return o->gently ? -1 : reject_merge(oldtree, o);
922                         if (current)
923                                 return o->gently ? -1 : reject_merge(current, o);
924                         if (newtree)
925                                 return o->gently ? -1 : reject_merge(newtree, o);
926                         return -1;
927                 }
928         }
929         else if (newtree) {
930                 if (oldtree && !o->initial_checkout) {
931                         /*
932                          * deletion of the path was staged;
933                          */
934                         if (same(oldtree, newtree))
935                                 return 1;
936                         return reject_merge(oldtree, o);
937                 }
938                 return merged_entry(newtree, current, o);
939         }
940         return deleted_entry(oldtree, current, o);
943 /*
944  * Bind merge.
945  *
946  * Keep the index entries at stage0, collapse stage1 but make sure
947  * stage0 does not have anything there.
948  */
949 int bind_merge(struct cache_entry **src,
950                 struct unpack_trees_options *o)
952         struct cache_entry *old = src[0];
953         struct cache_entry *a = src[1];
955         if (o->merge_size != 1)
956                 return error("Cannot do a bind merge of %d trees\n",
957                              o->merge_size);
958         if (a && old)
959                 return o->gently ? -1 :
960                         error(ERRORMSG(o, bind_overlap), a->name, old->name);
961         if (!a)
962                 return keep_entry(old, o);
963         else
964                 return merged_entry(a, NULL, o);
967 /*
968  * One-way merge.
969  *
970  * The rule is:
971  * - take the stat information from stage0, take the data from stage1
972  */
973 int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
975         struct cache_entry *old = src[0];
976         struct cache_entry *a = src[1];
978         if (o->merge_size != 1)
979                 return error("Cannot do a oneway merge of %d trees",
980                              o->merge_size);
982         if (!a)
983                 return deleted_entry(old, old, o);
985         if (old && same(old, a)) {
986                 int update = 0;
987                 if (o->reset) {
988                         struct stat st;
989                         if (lstat(old->name, &st) ||
990                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID))
991                                 update |= CE_UPDATE;
992                 }
993                 add_entry(o, old, update, 0);
994                 return 0;
995         }
996         return merged_entry(a, old, o);