Merge branch 'sg/travis-specific-cc'
[git] / merge-recursive.c
1 /*
2  * Recursive Merge algorithm stolen from git-merge-recursive.py by
3  * Fredrik Kuivinen.
4  * The thieves were Alex Riesen and Johannes Schindelin, in June/July 2006
5  */
6 #include "cache.h"
7 #include "config.h"
8 #include "advice.h"
9 #include "lockfile.h"
10 #include "cache-tree.h"
11 #include "object-store.h"
12 #include "repository.h"
13 #include "commit.h"
14 #include "blob.h"
15 #include "builtin.h"
16 #include "tree-walk.h"
17 #include "diff.h"
18 #include "diffcore.h"
19 #include "tag.h"
20 #include "alloc.h"
21 #include "unpack-trees.h"
22 #include "string-list.h"
23 #include "xdiff-interface.h"
24 #include "ll-merge.h"
25 #include "attr.h"
26 #include "merge-recursive.h"
27 #include "dir.h"
28 #include "submodule.h"
29 #include "revision.h"
30 #include "commit-reach.h"
31
32 struct path_hashmap_entry {
33         struct hashmap_entry e;
34         char path[FLEX_ARRAY];
35 };
36
37 static int path_hashmap_cmp(const void *cmp_data,
38                             const void *entry,
39                             const void *entry_or_key,
40                             const void *keydata)
41 {
42         const struct path_hashmap_entry *a = entry;
43         const struct path_hashmap_entry *b = entry_or_key;
44         const char *key = keydata;
45
46         if (ignore_case)
47                 return strcasecmp(a->path, key ? key : b->path);
48         else
49                 return strcmp(a->path, key ? key : b->path);
50 }
51
52 static unsigned int path_hash(const char *path)
53 {
54         return ignore_case ? strihash(path) : strhash(path);
55 }
56
57 static struct dir_rename_entry *dir_rename_find_entry(struct hashmap *hashmap,
58                                                       char *dir)
59 {
60         struct dir_rename_entry key;
61
62         if (dir == NULL)
63                 return NULL;
64         hashmap_entry_init(&key, strhash(dir));
65         key.dir = dir;
66         return hashmap_get(hashmap, &key, NULL);
67 }
68
69 static int dir_rename_cmp(const void *unused_cmp_data,
70                           const void *entry,
71                           const void *entry_or_key,
72                           const void *unused_keydata)
73 {
74         const struct dir_rename_entry *e1 = entry;
75         const struct dir_rename_entry *e2 = entry_or_key;
76
77         return strcmp(e1->dir, e2->dir);
78 }
79
80 static void dir_rename_init(struct hashmap *map)
81 {
82         hashmap_init(map, dir_rename_cmp, NULL, 0);
83 }
84
85 static void dir_rename_entry_init(struct dir_rename_entry *entry,
86                                   char *directory)
87 {
88         hashmap_entry_init(entry, strhash(directory));
89         entry->dir = directory;
90         entry->non_unique_new_dir = 0;
91         strbuf_init(&entry->new_dir, 0);
92         string_list_init(&entry->possible_new_dirs, 0);
93 }
94
95 static struct collision_entry *collision_find_entry(struct hashmap *hashmap,
96                                                     char *target_file)
97 {
98         struct collision_entry key;
99
100         hashmap_entry_init(&key, strhash(target_file));
101         key.target_file = target_file;
102         return hashmap_get(hashmap, &key, NULL);
103 }
104
105 static int collision_cmp(void *unused_cmp_data,
106                          const struct collision_entry *e1,
107                          const struct collision_entry *e2,
108                          const void *unused_keydata)
109 {
110         return strcmp(e1->target_file, e2->target_file);
111 }
112
113 static void collision_init(struct hashmap *map)
114 {
115         hashmap_init(map, (hashmap_cmp_fn) collision_cmp, NULL, 0);
116 }
117
118 static void flush_output(struct merge_options *o)
119 {
120         if (o->buffer_output < 2 && o->obuf.len) {
121                 fputs(o->obuf.buf, stdout);
122                 strbuf_reset(&o->obuf);
123         }
124 }
125
126 static int err(struct merge_options *o, const char *err, ...)
127 {
128         va_list params;
129
130         if (o->buffer_output < 2)
131                 flush_output(o);
132         else {
133                 strbuf_complete(&o->obuf, '\n');
134                 strbuf_addstr(&o->obuf, "error: ");
135         }
136         va_start(params, err);
137         strbuf_vaddf(&o->obuf, err, params);
138         va_end(params);
139         if (o->buffer_output > 1)
140                 strbuf_addch(&o->obuf, '\n');
141         else {
142                 error("%s", o->obuf.buf);
143                 strbuf_reset(&o->obuf);
144         }
145
146         return -1;
147 }
148
149 static struct tree *shift_tree_object(struct repository *repo,
150                                       struct tree *one, struct tree *two,
151                                       const char *subtree_shift)
152 {
153         struct object_id shifted;
154
155         if (!*subtree_shift) {
156                 shift_tree(&one->object.oid, &two->object.oid, &shifted, 0);
157         } else {
158                 shift_tree_by(&one->object.oid, &two->object.oid, &shifted,
159                               subtree_shift);
160         }
161         if (oideq(&two->object.oid, &shifted))
162                 return two;
163         return lookup_tree(repo, &shifted);
164 }
165
166 static struct commit *make_virtual_commit(struct repository *repo,
167                                           struct tree *tree,
168                                           const char *comment)
169 {
170         struct commit *commit = alloc_commit_node(repo);
171
172         set_merge_remote_desc(commit, comment, (struct object *)commit);
173         commit->maybe_tree = tree;
174         commit->object.parsed = 1;
175         return commit;
176 }
177
178 /*
179  * Since we use get_tree_entry(), which does not put the read object into
180  * the object pool, we cannot rely on a == b.
181  */
182 static int oid_eq(const struct object_id *a, const struct object_id *b)
183 {
184         if (!a && !b)
185                 return 2;
186         return a && b && oideq(a, b);
187 }
188
189 enum rename_type {
190         RENAME_NORMAL = 0,
191         RENAME_VIA_DIR,
192         RENAME_ADD,
193         RENAME_DELETE,
194         RENAME_ONE_FILE_TO_ONE,
195         RENAME_ONE_FILE_TO_TWO,
196         RENAME_TWO_FILES_TO_ONE
197 };
198
199 struct rename_conflict_info {
200         enum rename_type rename_type;
201         struct diff_filepair *pair1;
202         struct diff_filepair *pair2;
203         const char *branch1;
204         const char *branch2;
205         struct stage_data *dst_entry1;
206         struct stage_data *dst_entry2;
207         struct diff_filespec ren1_other;
208         struct diff_filespec ren2_other;
209 };
210
211 /*
212  * Since we want to write the index eventually, we cannot reuse the index
213  * for these (temporary) data.
214  */
215 struct stage_data {
216         struct {
217                 unsigned mode;
218                 struct object_id oid;
219         } stages[4];
220         struct rename_conflict_info *rename_conflict_info;
221         unsigned processed:1;
222 };
223
224 static inline void setup_rename_conflict_info(enum rename_type rename_type,
225                                               struct diff_filepair *pair1,
226                                               struct diff_filepair *pair2,
227                                               const char *branch1,
228                                               const char *branch2,
229                                               struct stage_data *dst_entry1,
230                                               struct stage_data *dst_entry2,
231                                               struct merge_options *o,
232                                               struct stage_data *src_entry1,
233                                               struct stage_data *src_entry2)
234 {
235         int ostage1 = 0, ostage2;
236         struct rename_conflict_info *ci;
237
238         /*
239          * When we have two renames involved, it's easiest to get the
240          * correct things into stage 2 and 3, and to make sure that the
241          * content merge puts HEAD before the other branch if we just
242          * ensure that branch1 == o->branch1.  So, simply flip arguments
243          * around if we don't have that.
244          */
245         if (dst_entry2 && branch1 != o->branch1) {
246                 setup_rename_conflict_info(rename_type,
247                                            pair2,      pair1,
248                                            branch2,    branch1,
249                                            dst_entry2, dst_entry1,
250                                            o,
251                                            src_entry2, src_entry1);
252                 return;
253         }
254
255         ci = xcalloc(1, sizeof(struct rename_conflict_info));
256         ci->rename_type = rename_type;
257         ci->pair1 = pair1;
258         ci->branch1 = branch1;
259         ci->branch2 = branch2;
260
261         ci->dst_entry1 = dst_entry1;
262         dst_entry1->rename_conflict_info = ci;
263         dst_entry1->processed = 0;
264
265         assert(!pair2 == !dst_entry2);
266         if (dst_entry2) {
267                 ci->dst_entry2 = dst_entry2;
268                 ci->pair2 = pair2;
269                 dst_entry2->rename_conflict_info = ci;
270         }
271
272         /*
273          * For each rename, there could have been
274          * modifications on the side of history where that
275          * file was not renamed.
276          */
277         if (rename_type == RENAME_ADD ||
278             rename_type == RENAME_TWO_FILES_TO_ONE) {
279                 ostage1 = o->branch1 == branch1 ? 3 : 2;
280
281                 ci->ren1_other.path = pair1->one->path;
282                 oidcpy(&ci->ren1_other.oid, &src_entry1->stages[ostage1].oid);
283                 ci->ren1_other.mode = src_entry1->stages[ostage1].mode;
284         }
285
286         if (rename_type == RENAME_TWO_FILES_TO_ONE) {
287                 ostage2 = ostage1 ^ 1;
288
289                 ci->ren2_other.path = pair2->one->path;
290                 oidcpy(&ci->ren2_other.oid, &src_entry2->stages[ostage2].oid);
291                 ci->ren2_other.mode = src_entry2->stages[ostage2].mode;
292         }
293 }
294
295 static int show(struct merge_options *o, int v)
296 {
297         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
298 }
299
300 __attribute__((format (printf, 3, 4)))
301 static void output(struct merge_options *o, int v, const char *fmt, ...)
302 {
303         va_list ap;
304
305         if (!show(o, v))
306                 return;
307
308         strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
309
310         va_start(ap, fmt);
311         strbuf_vaddf(&o->obuf, fmt, ap);
312         va_end(ap);
313
314         strbuf_addch(&o->obuf, '\n');
315         if (!o->buffer_output)
316                 flush_output(o);
317 }
318
319 static void output_commit_title(struct merge_options *o, struct commit *commit)
320 {
321         struct merge_remote_desc *desc;
322
323         strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
324         desc = merge_remote_util(commit);
325         if (desc)
326                 strbuf_addf(&o->obuf, "virtual %s\n", desc->name);
327         else {
328                 strbuf_add_unique_abbrev(&o->obuf, &commit->object.oid,
329                                          DEFAULT_ABBREV);
330                 strbuf_addch(&o->obuf, ' ');
331                 if (parse_commit(commit) != 0)
332                         strbuf_addstr(&o->obuf, _("(bad commit)\n"));
333                 else {
334                         const char *title;
335                         const char *msg = get_commit_buffer(commit, NULL);
336                         int len = find_commit_subject(msg, &title);
337                         if (len)
338                                 strbuf_addf(&o->obuf, "%.*s\n", len, title);
339                         unuse_commit_buffer(commit, msg);
340                 }
341         }
342         flush_output(o);
343 }
344
345 static int add_cacheinfo(struct merge_options *o,
346                          unsigned int mode, const struct object_id *oid,
347                          const char *path, int stage, int refresh, int options)
348 {
349         struct index_state *istate = o->repo->index;
350         struct cache_entry *ce;
351         int ret;
352
353         ce = make_cache_entry(istate, mode, oid ? oid : &null_oid, path, stage, 0);
354         if (!ce)
355                 return err(o, _("add_cacheinfo failed for path '%s'; merge aborting."), path);
356
357         ret = add_index_entry(istate, ce, options);
358         if (refresh) {
359                 struct cache_entry *nce;
360
361                 nce = refresh_cache_entry(istate, ce,
362                                           CE_MATCH_REFRESH | CE_MATCH_IGNORE_MISSING);
363                 if (!nce)
364                         return err(o, _("add_cacheinfo failed to refresh for path '%s'; merge aborting."), path);
365                 if (nce != ce)
366                         ret = add_index_entry(istate, nce, options);
367         }
368         return ret;
369 }
370
371 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
372 {
373         parse_tree(tree);
374         init_tree_desc(desc, tree->buffer, tree->size);
375 }
376
377 static int unpack_trees_start(struct merge_options *o,
378                               struct tree *common,
379                               struct tree *head,
380                               struct tree *merge)
381 {
382         int rc;
383         struct tree_desc t[3];
384         struct index_state tmp_index = { NULL };
385
386         memset(&o->unpack_opts, 0, sizeof(o->unpack_opts));
387         if (o->call_depth)
388                 o->unpack_opts.index_only = 1;
389         else
390                 o->unpack_opts.update = 1;
391         o->unpack_opts.merge = 1;
392         o->unpack_opts.head_idx = 2;
393         o->unpack_opts.fn = threeway_merge;
394         o->unpack_opts.src_index = o->repo->index;
395         o->unpack_opts.dst_index = &tmp_index;
396         o->unpack_opts.aggressive = !merge_detect_rename(o);
397         setup_unpack_trees_porcelain(&o->unpack_opts, "merge");
398
399         init_tree_desc_from_tree(t+0, common);
400         init_tree_desc_from_tree(t+1, head);
401         init_tree_desc_from_tree(t+2, merge);
402
403         rc = unpack_trees(3, t, &o->unpack_opts);
404         cache_tree_free(&o->repo->index->cache_tree);
405
406         /*
407          * Update o->repo->index to match the new results, AFTER saving a copy
408          * in o->orig_index.  Update src_index to point to the saved copy.
409          * (verify_uptodate() checks src_index, and the original index is
410          * the one that had the necessary modification timestamps.)
411          */
412         o->orig_index = *o->repo->index;
413         *o->repo->index = tmp_index;
414         o->unpack_opts.src_index = &o->orig_index;
415
416         return rc;
417 }
418
419 static void unpack_trees_finish(struct merge_options *o)
420 {
421         discard_index(&o->orig_index);
422         clear_unpack_trees_porcelain(&o->unpack_opts);
423 }
424
425 struct tree *write_tree_from_memory(struct merge_options *o)
426 {
427         struct tree *result = NULL;
428         struct index_state *istate = o->repo->index;
429
430         if (unmerged_index(istate)) {
431                 int i;
432                 fprintf(stderr, "BUG: There are unmerged index entries:\n");
433                 for (i = 0; i < istate->cache_nr; i++) {
434                         const struct cache_entry *ce = istate->cache[i];
435                         if (ce_stage(ce))
436                                 fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
437                                         (int)ce_namelen(ce), ce->name);
438                 }
439                 BUG("unmerged index entries in merge-recursive.c");
440         }
441
442         if (!istate->cache_tree)
443                 istate->cache_tree = cache_tree();
444
445         if (!cache_tree_fully_valid(istate->cache_tree) &&
446             cache_tree_update(istate, 0) < 0) {
447                 err(o, _("error building trees"));
448                 return NULL;
449         }
450
451         result = lookup_tree(o->repo, &istate->cache_tree->oid);
452
453         return result;
454 }
455
456 static int save_files_dirs(const struct object_id *oid,
457                            struct strbuf *base, const char *path,
458                            unsigned int mode, int stage, void *context)
459 {
460         struct path_hashmap_entry *entry;
461         int baselen = base->len;
462         struct merge_options *o = context;
463
464         strbuf_addstr(base, path);
465
466         FLEX_ALLOC_MEM(entry, path, base->buf, base->len);
467         hashmap_entry_init(entry, path_hash(entry->path));
468         hashmap_add(&o->current_file_dir_set, entry);
469
470         strbuf_setlen(base, baselen);
471         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
472 }
473
474 static void get_files_dirs(struct merge_options *o, struct tree *tree)
475 {
476         struct pathspec match_all;
477         memset(&match_all, 0, sizeof(match_all));
478         read_tree_recursive(the_repository, tree, "", 0, 0,
479                             &match_all, save_files_dirs, o);
480 }
481
482 static int get_tree_entry_if_blob(const struct object_id *tree,
483                                   const char *path,
484                                   struct object_id *hashy,
485                                   unsigned int *mode_o)
486 {
487         int ret;
488
489         ret = get_tree_entry(tree, path, hashy, mode_o);
490         if (S_ISDIR(*mode_o)) {
491                 oidcpy(hashy, &null_oid);
492                 *mode_o = 0;
493         }
494         return ret;
495 }
496
497 /*
498  * Returns an index_entry instance which doesn't have to correspond to
499  * a real cache entry in Git's index.
500  */
501 static struct stage_data *insert_stage_data(const char *path,
502                 struct tree *o, struct tree *a, struct tree *b,
503                 struct string_list *entries)
504 {
505         struct string_list_item *item;
506         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
507         get_tree_entry_if_blob(&o->object.oid, path,
508                                &e->stages[1].oid, &e->stages[1].mode);
509         get_tree_entry_if_blob(&a->object.oid, path,
510                                &e->stages[2].oid, &e->stages[2].mode);
511         get_tree_entry_if_blob(&b->object.oid, path,
512                                &e->stages[3].oid, &e->stages[3].mode);
513         item = string_list_insert(entries, path);
514         item->util = e;
515         return e;
516 }
517
518 /*
519  * Create a dictionary mapping file names to stage_data objects. The
520  * dictionary contains one entry for every path with a non-zero stage entry.
521  */
522 static struct string_list *get_unmerged(struct index_state *istate)
523 {
524         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
525         int i;
526
527         unmerged->strdup_strings = 1;
528
529         for (i = 0; i < istate->cache_nr; i++) {
530                 struct string_list_item *item;
531                 struct stage_data *e;
532                 const struct cache_entry *ce = istate->cache[i];
533                 if (!ce_stage(ce))
534                         continue;
535
536                 item = string_list_lookup(unmerged, ce->name);
537                 if (!item) {
538                         item = string_list_insert(unmerged, ce->name);
539                         item->util = xcalloc(1, sizeof(struct stage_data));
540                 }
541                 e = item->util;
542                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
543                 oidcpy(&e->stages[ce_stage(ce)].oid, &ce->oid);
544         }
545
546         return unmerged;
547 }
548
549 static int string_list_df_name_compare(const char *one, const char *two)
550 {
551         int onelen = strlen(one);
552         int twolen = strlen(two);
553         /*
554          * Here we only care that entries for D/F conflicts are
555          * adjacent, in particular with the file of the D/F conflict
556          * appearing before files below the corresponding directory.
557          * The order of the rest of the list is irrelevant for us.
558          *
559          * To achieve this, we sort with df_name_compare and provide
560          * the mode S_IFDIR so that D/F conflicts will sort correctly.
561          * We use the mode S_IFDIR for everything else for simplicity,
562          * since in other cases any changes in their order due to
563          * sorting cause no problems for us.
564          */
565         int cmp = df_name_compare(one, onelen, S_IFDIR,
566                                   two, twolen, S_IFDIR);
567         /*
568          * Now that 'foo' and 'foo/bar' compare equal, we have to make sure
569          * that 'foo' comes before 'foo/bar'.
570          */
571         if (cmp)
572                 return cmp;
573         return onelen - twolen;
574 }
575
576 static void record_df_conflict_files(struct merge_options *o,
577                                      struct string_list *entries)
578 {
579         /* If there is a D/F conflict and the file for such a conflict
580          * currently exists in the working tree, we want to allow it to be
581          * removed to make room for the corresponding directory if needed.
582          * The files underneath the directories of such D/F conflicts will
583          * be processed before the corresponding file involved in the D/F
584          * conflict.  If the D/F directory ends up being removed by the
585          * merge, then we won't have to touch the D/F file.  If the D/F
586          * directory needs to be written to the working copy, then the D/F
587          * file will simply be removed (in make_room_for_path()) to make
588          * room for the necessary paths.  Note that if both the directory
589          * and the file need to be present, then the D/F file will be
590          * reinstated with a new unique name at the time it is processed.
591          */
592         struct string_list df_sorted_entries = STRING_LIST_INIT_NODUP;
593         const char *last_file = NULL;
594         int last_len = 0;
595         int i;
596
597         /*
598          * If we're merging merge-bases, we don't want to bother with
599          * any working directory changes.
600          */
601         if (o->call_depth)
602                 return;
603
604         /* Ensure D/F conflicts are adjacent in the entries list. */
605         for (i = 0; i < entries->nr; i++) {
606                 struct string_list_item *next = &entries->items[i];
607                 string_list_append(&df_sorted_entries, next->string)->util =
608                                    next->util;
609         }
610         df_sorted_entries.cmp = string_list_df_name_compare;
611         string_list_sort(&df_sorted_entries);
612
613         string_list_clear(&o->df_conflict_file_set, 1);
614         for (i = 0; i < df_sorted_entries.nr; i++) {
615                 const char *path = df_sorted_entries.items[i].string;
616                 int len = strlen(path);
617                 struct stage_data *e = df_sorted_entries.items[i].util;
618
619                 /*
620                  * Check if last_file & path correspond to a D/F conflict;
621                  * i.e. whether path is last_file+'/'+<something>.
622                  * If so, record that it's okay to remove last_file to make
623                  * room for path and friends if needed.
624                  */
625                 if (last_file &&
626                     len > last_len &&
627                     memcmp(path, last_file, last_len) == 0 &&
628                     path[last_len] == '/') {
629                         string_list_insert(&o->df_conflict_file_set, last_file);
630                 }
631
632                 /*
633                  * Determine whether path could exist as a file in the
634                  * working directory as a possible D/F conflict.  This
635                  * will only occur when it exists in stage 2 as a
636                  * file.
637                  */
638                 if (S_ISREG(e->stages[2].mode) || S_ISLNK(e->stages[2].mode)) {
639                         last_file = path;
640                         last_len = len;
641                 } else {
642                         last_file = NULL;
643                 }
644         }
645         string_list_clear(&df_sorted_entries, 0);
646 }
647
648 struct rename {
649         struct diff_filepair *pair;
650         /*
651          * Purpose of src_entry and dst_entry:
652          *
653          * If 'before' is renamed to 'after' then src_entry will contain
654          * the versions of 'before' from the merge_base, HEAD, and MERGE in
655          * stages 1, 2, and 3; dst_entry will contain the respective
656          * versions of 'after' in corresponding locations.  Thus, we have a
657          * total of six modes and oids, though some will be null.  (Stage 0
658          * is ignored; we're interested in handling conflicts.)
659          *
660          * Since we don't turn on break-rewrites by default, neither
661          * src_entry nor dst_entry can have all three of their stages have
662          * non-null oids, meaning at most four of the six will be non-null.
663          * Also, since this is a rename, both src_entry and dst_entry will
664          * have at least one non-null oid, meaning at least two will be
665          * non-null.  Of the six oids, a typical rename will have three be
666          * non-null.  Only two implies a rename/delete, and four implies a
667          * rename/add.
668          */
669         struct stage_data *src_entry;
670         struct stage_data *dst_entry;
671         unsigned add_turned_into_rename:1;
672         unsigned processed:1;
673 };
674
675 static int update_stages(struct merge_options *opt, const char *path,
676                          const struct diff_filespec *o,
677                          const struct diff_filespec *a,
678                          const struct diff_filespec *b)
679 {
680
681         /*
682          * NOTE: It is usually a bad idea to call update_stages on a path
683          * before calling update_file on that same path, since it can
684          * sometimes lead to spurious "refusing to lose untracked file..."
685          * messages from update_file (via make_room_for path via
686          * would_lose_untracked).  Instead, reverse the order of the calls
687          * (executing update_file first and then update_stages).
688          */
689         int clear = 1;
690         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_SKIP_DFCHECK;
691         if (clear)
692                 if (remove_file_from_index(opt->repo->index, path))
693                         return -1;
694         if (o)
695                 if (add_cacheinfo(opt, o->mode, &o->oid, path, 1, 0, options))
696                         return -1;
697         if (a)
698                 if (add_cacheinfo(opt, a->mode, &a->oid, path, 2, 0, options))
699                         return -1;
700         if (b)
701                 if (add_cacheinfo(opt, b->mode, &b->oid, path, 3, 0, options))
702                         return -1;
703         return 0;
704 }
705
706 static void update_entry(struct stage_data *entry,
707                          struct diff_filespec *o,
708                          struct diff_filespec *a,
709                          struct diff_filespec *b)
710 {
711         entry->processed = 0;
712         entry->stages[1].mode = o->mode;
713         entry->stages[2].mode = a->mode;
714         entry->stages[3].mode = b->mode;
715         oidcpy(&entry->stages[1].oid, &o->oid);
716         oidcpy(&entry->stages[2].oid, &a->oid);
717         oidcpy(&entry->stages[3].oid, &b->oid);
718 }
719
720 static int remove_file(struct merge_options *o, int clean,
721                        const char *path, int no_wd)
722 {
723         int update_cache = o->call_depth || clean;
724         int update_working_directory = !o->call_depth && !no_wd;
725
726         if (update_cache) {
727                 if (remove_file_from_index(o->repo->index, path))
728                         return -1;
729         }
730         if (update_working_directory) {
731                 if (ignore_case) {
732                         struct cache_entry *ce;
733                         ce = index_file_exists(o->repo->index, path, strlen(path),
734                                                ignore_case);
735                         if (ce && ce_stage(ce) == 0 && strcmp(path, ce->name))
736                                 return 0;
737                 }
738                 if (remove_path(path))
739                         return -1;
740         }
741         return 0;
742 }
743
744 /* add a string to a strbuf, but converting "/" to "_" */
745 static void add_flattened_path(struct strbuf *out, const char *s)
746 {
747         size_t i = out->len;
748         strbuf_addstr(out, s);
749         for (; i < out->len; i++)
750                 if (out->buf[i] == '/')
751                         out->buf[i] = '_';
752 }
753
754 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
755 {
756         struct path_hashmap_entry *entry;
757         struct strbuf newpath = STRBUF_INIT;
758         int suffix = 0;
759         size_t base_len;
760
761         strbuf_addf(&newpath, "%s~", path);
762         add_flattened_path(&newpath, branch);
763
764         base_len = newpath.len;
765         while (hashmap_get_from_hash(&o->current_file_dir_set,
766                                      path_hash(newpath.buf), newpath.buf) ||
767                (!o->call_depth && file_exists(newpath.buf))) {
768                 strbuf_setlen(&newpath, base_len);
769                 strbuf_addf(&newpath, "_%d", suffix++);
770         }
771
772         FLEX_ALLOC_MEM(entry, path, newpath.buf, newpath.len);
773         hashmap_entry_init(entry, path_hash(entry->path));
774         hashmap_add(&o->current_file_dir_set, entry);
775         return strbuf_detach(&newpath, NULL);
776 }
777
778 /**
779  * Check whether a directory in the index is in the way of an incoming
780  * file.  Return 1 if so.  If check_working_copy is non-zero, also
781  * check the working directory.  If empty_ok is non-zero, also return
782  * 0 in the case where the working-tree dir exists but is empty.
783  */
784 static int dir_in_way(struct index_state *istate, const char *path,
785                       int check_working_copy, int empty_ok)
786 {
787         int pos;
788         struct strbuf dirpath = STRBUF_INIT;
789         struct stat st;
790
791         strbuf_addstr(&dirpath, path);
792         strbuf_addch(&dirpath, '/');
793
794         pos = index_name_pos(istate, dirpath.buf, dirpath.len);
795
796         if (pos < 0)
797                 pos = -1 - pos;
798         if (pos < istate->cache_nr &&
799             !strncmp(dirpath.buf, istate->cache[pos]->name, dirpath.len)) {
800                 strbuf_release(&dirpath);
801                 return 1;
802         }
803
804         strbuf_release(&dirpath);
805         return check_working_copy && !lstat(path, &st) && S_ISDIR(st.st_mode) &&
806                 !(empty_ok && is_empty_dir(path));
807 }
808
809 /*
810  * Returns whether path was tracked in the index before the merge started,
811  * and its oid and mode match the specified values
812  */
813 static int was_tracked_and_matches(struct merge_options *o, const char *path,
814                                    const struct object_id *oid, unsigned mode)
815 {
816         int pos = index_name_pos(&o->orig_index, path, strlen(path));
817         struct cache_entry *ce;
818
819         if (0 > pos)
820                 /* we were not tracking this path before the merge */
821                 return 0;
822
823         /* See if the file we were tracking before matches */
824         ce = o->orig_index.cache[pos];
825         return (oid_eq(&ce->oid, oid) && ce->ce_mode == mode);
826 }
827
828 /*
829  * Returns whether path was tracked in the index before the merge started
830  */
831 static int was_tracked(struct merge_options *o, const char *path)
832 {
833         int pos = index_name_pos(&o->orig_index, path, strlen(path));
834
835         if (0 <= pos)
836                 /* we were tracking this path before the merge */
837                 return 1;
838
839         return 0;
840 }
841
842 static int would_lose_untracked(struct merge_options *o, const char *path)
843 {
844         struct index_state *istate = o->repo->index;
845
846         /*
847          * This may look like it can be simplified to:
848          *   return !was_tracked(o, path) && file_exists(path)
849          * but it can't.  This function needs to know whether path was in
850          * the working tree due to EITHER having been tracked in the index
851          * before the merge OR having been put into the working copy and
852          * index by unpack_trees().  Due to that either-or requirement, we
853          * check the current index instead of the original one.
854          *
855          * Note that we do not need to worry about merge-recursive itself
856          * updating the index after unpack_trees() and before calling this
857          * function, because we strictly require all code paths in
858          * merge-recursive to update the working tree first and the index
859          * second.  Doing otherwise would break
860          * update_file()/would_lose_untracked(); see every comment in this
861          * file which mentions "update_stages".
862          */
863         int pos = index_name_pos(istate, path, strlen(path));
864
865         if (pos < 0)
866                 pos = -1 - pos;
867         while (pos < istate->cache_nr &&
868                !strcmp(path, istate->cache[pos]->name)) {
869                 /*
870                  * If stage #0, it is definitely tracked.
871                  * If it has stage #2 then it was tracked
872                  * before this merge started.  All other
873                  * cases the path was not tracked.
874                  */
875                 switch (ce_stage(istate->cache[pos])) {
876                 case 0:
877                 case 2:
878                         return 0;
879                 }
880                 pos++;
881         }
882         return file_exists(path);
883 }
884
885 static int was_dirty(struct merge_options *o, const char *path)
886 {
887         struct cache_entry *ce;
888         int dirty = 1;
889
890         if (o->call_depth || !was_tracked(o, path))
891                 return !dirty;
892
893         ce = index_file_exists(o->unpack_opts.src_index,
894                                path, strlen(path), ignore_case);
895         dirty = verify_uptodate(ce, &o->unpack_opts) != 0;
896         return dirty;
897 }
898
899 static int make_room_for_path(struct merge_options *o, const char *path)
900 {
901         int status, i;
902         const char *msg = _("failed to create path '%s'%s");
903
904         /* Unlink any D/F conflict files that are in the way */
905         for (i = 0; i < o->df_conflict_file_set.nr; i++) {
906                 const char *df_path = o->df_conflict_file_set.items[i].string;
907                 size_t pathlen = strlen(path);
908                 size_t df_pathlen = strlen(df_path);
909                 if (df_pathlen < pathlen &&
910                     path[df_pathlen] == '/' &&
911                     strncmp(path, df_path, df_pathlen) == 0) {
912                         output(o, 3,
913                                _("Removing %s to make room for subdirectory\n"),
914                                df_path);
915                         unlink(df_path);
916                         unsorted_string_list_delete_item(&o->df_conflict_file_set,
917                                                          i, 0);
918                         break;
919                 }
920         }
921
922         /* Make sure leading directories are created */
923         status = safe_create_leading_directories_const(path);
924         if (status) {
925                 if (status == SCLD_EXISTS)
926                         /* something else exists */
927                         return err(o, msg, path, _(": perhaps a D/F conflict?"));
928                 return err(o, msg, path, "");
929         }
930
931         /*
932          * Do not unlink a file in the work tree if we are not
933          * tracking it.
934          */
935         if (would_lose_untracked(o, path))
936                 return err(o, _("refusing to lose untracked file at '%s'"),
937                            path);
938
939         /* Successful unlink is good.. */
940         if (!unlink(path))
941                 return 0;
942         /* .. and so is no existing file */
943         if (errno == ENOENT)
944                 return 0;
945         /* .. but not some other error (who really cares what?) */
946         return err(o, msg, path, _(": perhaps a D/F conflict?"));
947 }
948
949 static int update_file_flags(struct merge_options *o,
950                              const struct object_id *oid,
951                              unsigned mode,
952                              const char *path,
953                              int update_cache,
954                              int update_wd)
955 {
956         int ret = 0;
957
958         if (o->call_depth)
959                 update_wd = 0;
960
961         if (update_wd) {
962                 enum object_type type;
963                 void *buf;
964                 unsigned long size;
965
966                 if (S_ISGITLINK(mode)) {
967                         /*
968                          * We may later decide to recursively descend into
969                          * the submodule directory and update its index
970                          * and/or work tree, but we do not do that now.
971                          */
972                         update_wd = 0;
973                         goto update_index;
974                 }
975
976                 buf = read_object_file(oid, &type, &size);
977                 if (!buf)
978                         return err(o, _("cannot read object %s '%s'"), oid_to_hex(oid), path);
979                 if (type != OBJ_BLOB) {
980                         ret = err(o, _("blob expected for %s '%s'"), oid_to_hex(oid), path);
981                         goto free_buf;
982                 }
983                 if (S_ISREG(mode)) {
984                         struct strbuf strbuf = STRBUF_INIT;
985                         if (convert_to_working_tree(o->repo->index, path, buf, size, &strbuf)) {
986                                 free(buf);
987                                 size = strbuf.len;
988                                 buf = strbuf_detach(&strbuf, NULL);
989                         }
990                 }
991
992                 if (make_room_for_path(o, path) < 0) {
993                         update_wd = 0;
994                         goto free_buf;
995                 }
996                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
997                         int fd;
998                         if (mode & 0100)
999                                 mode = 0777;
1000                         else
1001                                 mode = 0666;
1002                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
1003                         if (fd < 0) {
1004                                 ret = err(o, _("failed to open '%s': %s"),
1005                                           path, strerror(errno));
1006                                 goto free_buf;
1007                         }
1008                         write_in_full(fd, buf, size);
1009                         close(fd);
1010                 } else if (S_ISLNK(mode)) {
1011                         char *lnk = xmemdupz(buf, size);
1012                         safe_create_leading_directories_const(path);
1013                         unlink(path);
1014                         if (symlink(lnk, path))
1015                                 ret = err(o, _("failed to symlink '%s': %s"),
1016                                           path, strerror(errno));
1017                         free(lnk);
1018                 } else
1019                         ret = err(o,
1020                                   _("do not know what to do with %06o %s '%s'"),
1021                                   mode, oid_to_hex(oid), path);
1022         free_buf:
1023                 free(buf);
1024         }
1025 update_index:
1026         if (!ret && update_cache)
1027                 if (add_cacheinfo(o, mode, oid, path, 0, update_wd,
1028                                   ADD_CACHE_OK_TO_ADD))
1029                         return -1;
1030         return ret;
1031 }
1032
1033 static int update_file(struct merge_options *o,
1034                        int clean,
1035                        const struct object_id *oid,
1036                        unsigned mode,
1037                        const char *path)
1038 {
1039         return update_file_flags(o, oid, mode, path, o->call_depth || clean, !o->call_depth);
1040 }
1041
1042 /* Low level file merging, update and removal */
1043
1044 struct merge_file_info {
1045         struct object_id oid;
1046         unsigned mode;
1047         unsigned clean:1,
1048                  merge:1;
1049 };
1050
1051 static int merge_3way(struct merge_options *o,
1052                       mmbuffer_t *result_buf,
1053                       const struct diff_filespec *one,
1054                       const struct diff_filespec *a,
1055                       const struct diff_filespec *b,
1056                       const char *branch1,
1057                       const char *branch2,
1058                       const int extra_marker_size)
1059 {
1060         mmfile_t orig, src1, src2;
1061         struct ll_merge_options ll_opts = {0};
1062         char *base_name, *name1, *name2;
1063         int merge_status;
1064
1065         ll_opts.renormalize = o->renormalize;
1066         ll_opts.extra_marker_size = extra_marker_size;
1067         ll_opts.xdl_opts = o->xdl_opts;
1068
1069         if (o->call_depth) {
1070                 ll_opts.virtual_ancestor = 1;
1071                 ll_opts.variant = 0;
1072         } else {
1073                 switch (o->recursive_variant) {
1074                 case MERGE_RECURSIVE_OURS:
1075                         ll_opts.variant = XDL_MERGE_FAVOR_OURS;
1076                         break;
1077                 case MERGE_RECURSIVE_THEIRS:
1078                         ll_opts.variant = XDL_MERGE_FAVOR_THEIRS;
1079                         break;
1080                 default:
1081                         ll_opts.variant = 0;
1082                         break;
1083                 }
1084         }
1085
1086         if (strcmp(a->path, b->path) ||
1087             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
1088                 base_name = o->ancestor == NULL ? NULL :
1089                         mkpathdup("%s:%s", o->ancestor, one->path);
1090                 name1 = mkpathdup("%s:%s", branch1, a->path);
1091                 name2 = mkpathdup("%s:%s", branch2, b->path);
1092         } else {
1093                 base_name = o->ancestor == NULL ? NULL :
1094                         mkpathdup("%s", o->ancestor);
1095                 name1 = mkpathdup("%s", branch1);
1096                 name2 = mkpathdup("%s", branch2);
1097         }
1098
1099         read_mmblob(&orig, &one->oid);
1100         read_mmblob(&src1, &a->oid);
1101         read_mmblob(&src2, &b->oid);
1102
1103         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
1104                                 &src1, name1, &src2, name2,
1105                                 o->repo->index, &ll_opts);
1106
1107         free(base_name);
1108         free(name1);
1109         free(name2);
1110         free(orig.ptr);
1111         free(src1.ptr);
1112         free(src2.ptr);
1113         return merge_status;
1114 }
1115
1116 static int find_first_merges(struct repository *repo,
1117                              struct object_array *result, const char *path,
1118                              struct commit *a, struct commit *b)
1119 {
1120         int i, j;
1121         struct object_array merges = OBJECT_ARRAY_INIT;
1122         struct commit *commit;
1123         int contains_another;
1124
1125         char merged_revision[42];
1126         const char *rev_args[] = { "rev-list", "--merges", "--ancestry-path",
1127                                    "--all", merged_revision, NULL };
1128         struct rev_info revs;
1129         struct setup_revision_opt rev_opts;
1130
1131         memset(result, 0, sizeof(struct object_array));
1132         memset(&rev_opts, 0, sizeof(rev_opts));
1133
1134         /* get all revisions that merge commit a */
1135         xsnprintf(merged_revision, sizeof(merged_revision), "^%s",
1136                   oid_to_hex(&a->object.oid));
1137         repo_init_revisions(repo, &revs, NULL);
1138         rev_opts.submodule = path;
1139         /* FIXME: can't handle linked worktrees in submodules yet */
1140         revs.single_worktree = path != NULL;
1141         setup_revisions(ARRAY_SIZE(rev_args)-1, rev_args, &revs, &rev_opts);
1142
1143         /* save all revisions from the above list that contain b */
1144         if (prepare_revision_walk(&revs))
1145                 die("revision walk setup failed");
1146         while ((commit = get_revision(&revs)) != NULL) {
1147                 struct object *o = &(commit->object);
1148                 if (in_merge_bases(b, commit))
1149                         add_object_array(o, NULL, &merges);
1150         }
1151         reset_revision_walk();
1152
1153         /* Now we've got all merges that contain a and b. Prune all
1154          * merges that contain another found merge and save them in
1155          * result.
1156          */
1157         for (i = 0; i < merges.nr; i++) {
1158                 struct commit *m1 = (struct commit *) merges.objects[i].item;
1159
1160                 contains_another = 0;
1161                 for (j = 0; j < merges.nr; j++) {
1162                         struct commit *m2 = (struct commit *) merges.objects[j].item;
1163                         if (i != j && in_merge_bases(m2, m1)) {
1164                                 contains_another = 1;
1165                                 break;
1166                         }
1167                 }
1168
1169                 if (!contains_another)
1170                         add_object_array(merges.objects[i].item, NULL, result);
1171         }
1172
1173         object_array_clear(&merges);
1174         return result->nr;
1175 }
1176
1177 static void print_commit(struct commit *commit)
1178 {
1179         struct strbuf sb = STRBUF_INIT;
1180         struct pretty_print_context ctx = {0};
1181         ctx.date_mode.type = DATE_NORMAL;
1182         format_commit_message(commit, " %h: %m %s", &sb, &ctx);
1183         fprintf(stderr, "%s\n", sb.buf);
1184         strbuf_release(&sb);
1185 }
1186
1187 static int merge_submodule(struct merge_options *o,
1188                            struct object_id *result, const char *path,
1189                            const struct object_id *base, const struct object_id *a,
1190                            const struct object_id *b)
1191 {
1192         struct commit *commit_base, *commit_a, *commit_b;
1193         int parent_count;
1194         struct object_array merges;
1195
1196         int i;
1197         int search = !o->call_depth;
1198
1199         /* store a in result in case we fail */
1200         oidcpy(result, a);
1201
1202         /* we can not handle deletion conflicts */
1203         if (is_null_oid(base))
1204                 return 0;
1205         if (is_null_oid(a))
1206                 return 0;
1207         if (is_null_oid(b))
1208                 return 0;
1209
1210         if (add_submodule_odb(path)) {
1211                 output(o, 1, _("Failed to merge submodule %s (not checked out)"), path);
1212                 return 0;
1213         }
1214
1215         if (!(commit_base = lookup_commit_reference(o->repo, base)) ||
1216             !(commit_a = lookup_commit_reference(o->repo, a)) ||
1217             !(commit_b = lookup_commit_reference(o->repo, b))) {
1218                 output(o, 1, _("Failed to merge submodule %s (commits not present)"), path);
1219                 return 0;
1220         }
1221
1222         /* check whether both changes are forward */
1223         if (!in_merge_bases(commit_base, commit_a) ||
1224             !in_merge_bases(commit_base, commit_b)) {
1225                 output(o, 1, _("Failed to merge submodule %s (commits don't follow merge-base)"), path);
1226                 return 0;
1227         }
1228
1229         /* Case #1: a is contained in b or vice versa */
1230         if (in_merge_bases(commit_a, commit_b)) {
1231                 oidcpy(result, b);
1232                 if (show(o, 3)) {
1233                         output(o, 3, _("Fast-forwarding submodule %s to the following commit:"), path);
1234                         output_commit_title(o, commit_b);
1235                 } else if (show(o, 2))
1236                         output(o, 2, _("Fast-forwarding submodule %s"), path);
1237                 else
1238                         ; /* no output */
1239
1240                 return 1;
1241         }
1242         if (in_merge_bases(commit_b, commit_a)) {
1243                 oidcpy(result, a);
1244                 if (show(o, 3)) {
1245                         output(o, 3, _("Fast-forwarding submodule %s to the following commit:"), path);
1246                         output_commit_title(o, commit_a);
1247                 } else if (show(o, 2))
1248                         output(o, 2, _("Fast-forwarding submodule %s"), path);
1249                 else
1250                         ; /* no output */
1251
1252                 return 1;
1253         }
1254
1255         /*
1256          * Case #2: There are one or more merges that contain a and b in
1257          * the submodule. If there is only one, then present it as a
1258          * suggestion to the user, but leave it marked unmerged so the
1259          * user needs to confirm the resolution.
1260          */
1261
1262         /* Skip the search if makes no sense to the calling context.  */
1263         if (!search)
1264                 return 0;
1265
1266         /* find commit which merges them */
1267         parent_count = find_first_merges(o->repo, &merges, path,
1268                                          commit_a, commit_b);
1269         switch (parent_count) {
1270         case 0:
1271                 output(o, 1, _("Failed to merge submodule %s (merge following commits not found)"), path);
1272                 break;
1273
1274         case 1:
1275                 output(o, 1, _("Failed to merge submodule %s (not fast-forward)"), path);
1276                 output(o, 2, _("Found a possible merge resolution for the submodule:\n"));
1277                 print_commit((struct commit *) merges.objects[0].item);
1278                 output(o, 2, _(
1279                        "If this is correct simply add it to the index "
1280                        "for example\n"
1281                        "by using:\n\n"
1282                        "  git update-index --cacheinfo 160000 %s \"%s\"\n\n"
1283                        "which will accept this suggestion.\n"),
1284                        oid_to_hex(&merges.objects[0].item->oid), path);
1285                 break;
1286
1287         default:
1288                 output(o, 1, _("Failed to merge submodule %s (multiple merges found)"), path);
1289                 for (i = 0; i < merges.nr; i++)
1290                         print_commit((struct commit *) merges.objects[i].item);
1291         }
1292
1293         object_array_clear(&merges);
1294         return 0;
1295 }
1296
1297 static int merge_mode_and_contents(struct merge_options *o,
1298                                    const struct diff_filespec *one,
1299                                    const struct diff_filespec *a,
1300                                    const struct diff_filespec *b,
1301                                    const char *filename,
1302                                    const char *branch1,
1303                                    const char *branch2,
1304                                    const int extra_marker_size,
1305                                    struct merge_file_info *result)
1306 {
1307         if (o->branch1 != branch1) {
1308                 /*
1309                  * It's weird getting a reverse merge with HEAD on the bottom
1310                  * side of the conflict markers and the other branch on the
1311                  * top.  Fix that.
1312                  */
1313                 return merge_mode_and_contents(o, one, b, a,
1314                                                filename,
1315                                                branch2, branch1,
1316                                                extra_marker_size, result);
1317         }
1318
1319         result->merge = 0;
1320         result->clean = 1;
1321
1322         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
1323                 result->clean = 0;
1324                 if (S_ISREG(a->mode)) {
1325                         result->mode = a->mode;
1326                         oidcpy(&result->oid, &a->oid);
1327                 } else {
1328                         result->mode = b->mode;
1329                         oidcpy(&result->oid, &b->oid);
1330                 }
1331         } else {
1332                 if (!oid_eq(&a->oid, &one->oid) && !oid_eq(&b->oid, &one->oid))
1333                         result->merge = 1;
1334
1335                 /*
1336                  * Merge modes
1337                  */
1338                 if (a->mode == b->mode || a->mode == one->mode)
1339                         result->mode = b->mode;
1340                 else {
1341                         result->mode = a->mode;
1342                         if (b->mode != one->mode) {
1343                                 result->clean = 0;
1344                                 result->merge = 1;
1345                         }
1346                 }
1347
1348                 if (oid_eq(&a->oid, &b->oid) || oid_eq(&a->oid, &one->oid))
1349                         oidcpy(&result->oid, &b->oid);
1350                 else if (oid_eq(&b->oid, &one->oid))
1351                         oidcpy(&result->oid, &a->oid);
1352                 else if (S_ISREG(a->mode)) {
1353                         mmbuffer_t result_buf;
1354                         int ret = 0, merge_status;
1355
1356                         merge_status = merge_3way(o, &result_buf, one, a, b,
1357                                                   branch1, branch2,
1358                                                   extra_marker_size);
1359
1360                         if ((merge_status < 0) || !result_buf.ptr)
1361                                 ret = err(o, _("Failed to execute internal merge"));
1362
1363                         if (!ret &&
1364                             write_object_file(result_buf.ptr, result_buf.size,
1365                                               blob_type, &result->oid))
1366                                 ret = err(o, _("Unable to add %s to database"),
1367                                           a->path);
1368
1369                         free(result_buf.ptr);
1370                         if (ret)
1371                                 return ret;
1372                         result->clean = (merge_status == 0);
1373                 } else if (S_ISGITLINK(a->mode)) {
1374                         result->clean = merge_submodule(o, &result->oid,
1375                                                         one->path,
1376                                                         &one->oid,
1377                                                         &a->oid,
1378                                                         &b->oid);
1379                 } else if (S_ISLNK(a->mode)) {
1380                         switch (o->recursive_variant) {
1381                         case MERGE_RECURSIVE_NORMAL:
1382                                 oidcpy(&result->oid, &a->oid);
1383                                 if (!oid_eq(&a->oid, &b->oid))
1384                                         result->clean = 0;
1385                                 break;
1386                         case MERGE_RECURSIVE_OURS:
1387                                 oidcpy(&result->oid, &a->oid);
1388                                 break;
1389                         case MERGE_RECURSIVE_THEIRS:
1390                                 oidcpy(&result->oid, &b->oid);
1391                                 break;
1392                         }
1393                 } else
1394                         BUG("unsupported object type in the tree");
1395         }
1396
1397         if (result->merge)
1398                 output(o, 2, _("Auto-merging %s"), filename);
1399
1400         return 0;
1401 }
1402
1403 static int handle_rename_via_dir(struct merge_options *o,
1404                                  struct diff_filepair *pair,
1405                                  const char *rename_branch,
1406                                  const char *other_branch)
1407 {
1408         /*
1409          * Handle file adds that need to be renamed due to directory rename
1410          * detection.  This differs from handle_rename_normal, because
1411          * there is no content merge to do; just move the file into the
1412          * desired final location.
1413          */
1414         const struct diff_filespec *dest = pair->two;
1415
1416         if (!o->call_depth && would_lose_untracked(o, dest->path)) {
1417                 char *alt_path = unique_path(o, dest->path, rename_branch);
1418
1419                 output(o, 1, _("Error: Refusing to lose untracked file at %s; "
1420                                "writing to %s instead."),
1421                        dest->path, alt_path);
1422                 /*
1423                  * Write the file in worktree at alt_path, but not in the
1424                  * index.  Instead, write to dest->path for the index but
1425                  * only at the higher appropriate stage.
1426                  */
1427                 if (update_file(o, 0, &dest->oid, dest->mode, alt_path))
1428                         return -1;
1429                 free(alt_path);
1430                 return update_stages(o, dest->path, NULL,
1431                                      rename_branch == o->branch1 ? dest : NULL,
1432                                      rename_branch == o->branch1 ? NULL : dest);
1433         }
1434
1435         /* Update dest->path both in index and in worktree */
1436         if (update_file(o, 1, &dest->oid, dest->mode, dest->path))
1437                 return -1;
1438         return 0;
1439 }
1440
1441 static int handle_change_delete(struct merge_options *o,
1442                                 const char *path, const char *old_path,
1443                                 const struct object_id *o_oid, int o_mode,
1444                                 const struct object_id *changed_oid,
1445                                 int changed_mode,
1446                                 const char *change_branch,
1447                                 const char *delete_branch,
1448                                 const char *change, const char *change_past)
1449 {
1450         char *alt_path = NULL;
1451         const char *update_path = path;
1452         int ret = 0;
1453
1454         if (dir_in_way(o->repo->index, path, !o->call_depth, 0) ||
1455             (!o->call_depth && would_lose_untracked(o, path))) {
1456                 update_path = alt_path = unique_path(o, path, change_branch);
1457         }
1458
1459         if (o->call_depth) {
1460                 /*
1461                  * We cannot arbitrarily accept either a_sha or b_sha as
1462                  * correct; since there is no true "middle point" between
1463                  * them, simply reuse the base version for virtual merge base.
1464                  */
1465                 ret = remove_file_from_index(o->repo->index, path);
1466                 if (!ret)
1467                         ret = update_file(o, 0, o_oid, o_mode, update_path);
1468         } else {
1469                 /*
1470                  * Despite the four nearly duplicate messages and argument
1471                  * lists below and the ugliness of the nested if-statements,
1472                  * having complete messages makes the job easier for
1473                  * translators.
1474                  *
1475                  * The slight variance among the cases is due to the fact
1476                  * that:
1477                  *   1) directory/file conflicts (in effect if
1478                  *      !alt_path) could cause us to need to write the
1479                  *      file to a different path.
1480                  *   2) renames (in effect if !old_path) could mean that
1481                  *      there are two names for the path that the user
1482                  *      may know the file by.
1483                  */
1484                 if (!alt_path) {
1485                         if (!old_path) {
1486                                 output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1487                                        "and %s in %s. Version %s of %s left in tree."),
1488                                        change, path, delete_branch, change_past,
1489                                        change_branch, change_branch, path);
1490                         } else {
1491                                 output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1492                                        "and %s to %s in %s. Version %s of %s left in tree."),
1493                                        change, old_path, delete_branch, change_past, path,
1494                                        change_branch, change_branch, path);
1495                         }
1496                 } else {
1497                         if (!old_path) {
1498                                 output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1499                                        "and %s in %s. Version %s of %s left in tree at %s."),
1500                                        change, path, delete_branch, change_past,
1501                                        change_branch, change_branch, path, alt_path);
1502                         } else {
1503                                 output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1504                                        "and %s to %s in %s. Version %s of %s left in tree at %s."),
1505                                        change, old_path, delete_branch, change_past, path,
1506                                        change_branch, change_branch, path, alt_path);
1507                         }
1508                 }
1509                 /*
1510                  * No need to call update_file() on path when change_branch ==
1511                  * o->branch1 && !alt_path, since that would needlessly touch
1512                  * path.  We could call update_file_flags() with update_cache=0
1513                  * and update_wd=0, but that's a no-op.
1514                  */
1515                 if (change_branch != o->branch1 || alt_path)
1516                         ret = update_file(o, 0, changed_oid, changed_mode, update_path);
1517         }
1518         free(alt_path);
1519
1520         return ret;
1521 }
1522
1523 static int handle_rename_delete(struct merge_options *o,
1524                                 struct diff_filepair *pair,
1525                                 const char *rename_branch,
1526                                 const char *delete_branch)
1527 {
1528         const struct diff_filespec *orig = pair->one;
1529         const struct diff_filespec *dest = pair->two;
1530
1531         if (handle_change_delete(o,
1532                                  o->call_depth ? orig->path : dest->path,
1533                                  o->call_depth ? NULL : orig->path,
1534                                  &orig->oid, orig->mode,
1535                                  &dest->oid, dest->mode,
1536                                  rename_branch, delete_branch,
1537                                  _("rename"), _("renamed")))
1538                 return -1;
1539
1540         if (o->call_depth)
1541                 return remove_file_from_index(o->repo->index, dest->path);
1542         else
1543                 return update_stages(o, dest->path, NULL,
1544                                      rename_branch == o->branch1 ? dest : NULL,
1545                                      rename_branch == o->branch1 ? NULL : dest);
1546 }
1547
1548 static struct diff_filespec *filespec_from_entry(struct diff_filespec *target,
1549                                                  struct stage_data *entry,
1550                                                  int stage)
1551 {
1552         struct object_id *oid = &entry->stages[stage].oid;
1553         unsigned mode = entry->stages[stage].mode;
1554         if (mode == 0 || is_null_oid(oid))
1555                 return NULL;
1556         oidcpy(&target->oid, oid);
1557         target->mode = mode;
1558         return target;
1559 }
1560
1561 static int handle_file_collision(struct merge_options *o,
1562                                  const char *collide_path,
1563                                  const char *prev_path1,
1564                                  const char *prev_path2,
1565                                  const char *branch1, const char *branch2,
1566                                  const struct object_id *a_oid,
1567                                  unsigned int a_mode,
1568                                  const struct object_id *b_oid,
1569                                  unsigned int b_mode)
1570 {
1571         struct merge_file_info mfi;
1572         struct diff_filespec null, a, b;
1573         char *alt_path = NULL;
1574         const char *update_path = collide_path;
1575
1576         /*
1577          * It's easiest to get the correct things into stage 2 and 3, and
1578          * to make sure that the content merge puts HEAD before the other
1579          * branch if we just ensure that branch1 == o->branch1.  So, simply
1580          * flip arguments around if we don't have that.
1581          */
1582         if (branch1 != o->branch1) {
1583                 return handle_file_collision(o, collide_path,
1584                                              prev_path2, prev_path1,
1585                                              branch2, branch1,
1586                                              b_oid, b_mode,
1587                                              a_oid, a_mode);
1588         }
1589
1590         /*
1591          * In the recursive case, we just opt to undo renames
1592          */
1593         if (o->call_depth && (prev_path1 || prev_path2)) {
1594                 /* Put first file (a_oid, a_mode) in its original spot */
1595                 if (prev_path1) {
1596                         if (update_file(o, 1, a_oid, a_mode, prev_path1))
1597                                 return -1;
1598                 } else {
1599                         if (update_file(o, 1, a_oid, a_mode, collide_path))
1600                                 return -1;
1601                 }
1602
1603                 /* Put second file (b_oid, b_mode) in its original spot */
1604                 if (prev_path2) {
1605                         if (update_file(o, 1, b_oid, b_mode, prev_path2))
1606                                 return -1;
1607                 } else {
1608                         if (update_file(o, 1, b_oid, b_mode, collide_path))
1609                                 return -1;
1610                 }
1611
1612                 /* Don't leave something at collision path if unrenaming both */
1613                 if (prev_path1 && prev_path2)
1614                         remove_file(o, 1, collide_path, 0);
1615
1616                 return 0;
1617         }
1618
1619         /* Remove rename sources if rename/add or rename/rename(2to1) */
1620         if (prev_path1)
1621                 remove_file(o, 1, prev_path1,
1622                             o->call_depth || would_lose_untracked(o, prev_path1));
1623         if (prev_path2)
1624                 remove_file(o, 1, prev_path2,
1625                             o->call_depth || would_lose_untracked(o, prev_path2));
1626
1627         /*
1628          * Remove the collision path, if it wouldn't cause dirty contents
1629          * or an untracked file to get lost.  We'll either overwrite with
1630          * merged contents, or just write out to differently named files.
1631          */
1632         if (was_dirty(o, collide_path)) {
1633                 output(o, 1, _("Refusing to lose dirty file at %s"),
1634                        collide_path);
1635                 update_path = alt_path = unique_path(o, collide_path, "merged");
1636         } else if (would_lose_untracked(o, collide_path)) {
1637                 /*
1638                  * Only way we get here is if both renames were from
1639                  * a directory rename AND user had an untracked file
1640                  * at the location where both files end up after the
1641                  * two directory renames.  See testcase 10d of t6043.
1642                  */
1643                 output(o, 1, _("Refusing to lose untracked file at "
1644                                "%s, even though it's in the way."),
1645                        collide_path);
1646                 update_path = alt_path = unique_path(o, collide_path, "merged");
1647         } else {
1648                 /*
1649                  * FIXME: It's possible that the two files are identical
1650                  * and that the current working copy happens to match, in
1651                  * which case we are unnecessarily touching the working
1652                  * tree file.  It's not a likely enough scenario that I
1653                  * want to code up the checks for it and a better fix is
1654                  * available if we restructure how unpack_trees() and
1655                  * merge-recursive interoperate anyway, so punting for
1656                  * now...
1657                  */
1658                 remove_file(o, 0, collide_path, 0);
1659         }
1660
1661         /* Store things in diff_filespecs for functions that need it */
1662         memset(&a, 0, sizeof(struct diff_filespec));
1663         memset(&b, 0, sizeof(struct diff_filespec));
1664         null.path = a.path = b.path = (char *)collide_path;
1665         oidcpy(&null.oid, &null_oid);
1666         null.mode = 0;
1667         oidcpy(&a.oid, a_oid);
1668         a.mode = a_mode;
1669         a.oid_valid = 1;
1670         oidcpy(&b.oid, b_oid);
1671         b.mode = b_mode;
1672         b.oid_valid = 1;
1673
1674         if (merge_mode_and_contents(o, &null, &a, &b, collide_path,
1675                                     branch1, branch2, o->call_depth * 2, &mfi))
1676                 return -1;
1677         mfi.clean &= !alt_path;
1678         if (update_file(o, mfi.clean, &mfi.oid, mfi.mode, update_path))
1679                 return -1;
1680         if (!mfi.clean && !o->call_depth &&
1681             update_stages(o, collide_path, NULL, &a, &b))
1682                 return -1;
1683         free(alt_path);
1684         /*
1685          * FIXME: If both a & b both started with conflicts (only possible
1686          * if they came from a rename/rename(2to1)), but had IDENTICAL
1687          * contents including those conflicts, then in the next line we claim
1688          * it was clean.  If someone cares about this case, we should have the
1689          * caller notify us if we started with conflicts.
1690          */
1691         return mfi.clean;
1692 }
1693
1694 static int handle_rename_add(struct merge_options *o,
1695                              struct rename_conflict_info *ci)
1696 {
1697         /* a was renamed to c, and a separate c was added. */
1698         struct diff_filespec *a = ci->pair1->one;
1699         struct diff_filespec *c = ci->pair1->two;
1700         char *path = c->path;
1701         char *prev_path_desc;
1702         struct merge_file_info mfi;
1703
1704         int other_stage = (ci->branch1 == o->branch1 ? 3 : 2);
1705
1706         output(o, 1, _("CONFLICT (rename/add): "
1707                "Rename %s->%s in %s.  Added %s in %s"),
1708                a->path, c->path, ci->branch1,
1709                c->path, ci->branch2);
1710
1711         prev_path_desc = xstrfmt("version of %s from %s", path, a->path);
1712         if (merge_mode_and_contents(o, a, c, &ci->ren1_other, prev_path_desc,
1713                                     o->branch1, o->branch2,
1714                                     1 + o->call_depth * 2, &mfi))
1715                 return -1;
1716         free(prev_path_desc);
1717
1718         return handle_file_collision(o,
1719                                      c->path, a->path, NULL,
1720                                      ci->branch1, ci->branch2,
1721                                      &mfi.oid, mfi.mode,
1722                                      &ci->dst_entry1->stages[other_stage].oid,
1723                                      ci->dst_entry1->stages[other_stage].mode);
1724 }
1725
1726 static char *find_path_for_conflict(struct merge_options *o,
1727                                     const char *path,
1728                                     const char *branch1,
1729                                     const char *branch2)
1730 {
1731         char *new_path = NULL;
1732         if (dir_in_way(o->repo->index, path, !o->call_depth, 0)) {
1733                 new_path = unique_path(o, path, branch1);
1734                 output(o, 1, _("%s is a directory in %s adding "
1735                                "as %s instead"),
1736                        path, branch2, new_path);
1737         } else if (would_lose_untracked(o, path)) {
1738                 new_path = unique_path(o, path, branch1);
1739                 output(o, 1, _("Refusing to lose untracked file"
1740                                " at %s; adding as %s instead"),
1741                        path, new_path);
1742         }
1743
1744         return new_path;
1745 }
1746
1747 static int handle_rename_rename_1to2(struct merge_options *o,
1748                                      struct rename_conflict_info *ci)
1749 {
1750         /* One file was renamed in both branches, but to different names. */
1751         struct merge_file_info mfi;
1752         struct diff_filespec other;
1753         struct diff_filespec *add;
1754         struct diff_filespec *one = ci->pair1->one;
1755         struct diff_filespec *a = ci->pair1->two;
1756         struct diff_filespec *b = ci->pair2->two;
1757         char *path_desc;
1758
1759         output(o, 1, _("CONFLICT (rename/rename): "
1760                "Rename \"%s\"->\"%s\" in branch \"%s\" "
1761                "rename \"%s\"->\"%s\" in \"%s\"%s"),
1762                one->path, a->path, ci->branch1,
1763                one->path, b->path, ci->branch2,
1764                o->call_depth ? _(" (left unresolved)") : "");
1765
1766         path_desc = xstrfmt("%s and %s, both renamed from %s",
1767                             a->path, b->path, one->path);
1768         if (merge_mode_and_contents(o, one, a, b, path_desc,
1769                                     ci->branch1, ci->branch2,
1770                                     o->call_depth * 2, &mfi))
1771                 return -1;
1772         free(path_desc);
1773
1774         if (o->call_depth) {
1775                 /*
1776                  * FIXME: For rename/add-source conflicts (if we could detect
1777                  * such), this is wrong.  We should instead find a unique
1778                  * pathname and then either rename the add-source file to that
1779                  * unique path, or use that unique path instead of src here.
1780                  */
1781                 if (update_file(o, 0, &mfi.oid, mfi.mode, one->path))
1782                         return -1;
1783
1784                 /*
1785                  * Above, we put the merged content at the merge-base's
1786                  * path.  Now we usually need to delete both a->path and
1787                  * b->path.  However, the rename on each side of the merge
1788                  * could also be involved in a rename/add conflict.  In
1789                  * such cases, we should keep the added file around,
1790                  * resolving the conflict at that path in its favor.
1791                  */
1792                 add = filespec_from_entry(&other, ci->dst_entry1, 2 ^ 1);
1793                 if (add) {
1794                         if (update_file(o, 0, &add->oid, add->mode, a->path))
1795                                 return -1;
1796                 }
1797                 else
1798                         remove_file_from_index(o->repo->index, a->path);
1799                 add = filespec_from_entry(&other, ci->dst_entry2, 3 ^ 1);
1800                 if (add) {
1801                         if (update_file(o, 0, &add->oid, add->mode, b->path))
1802                                 return -1;
1803                 }
1804                 else
1805                         remove_file_from_index(o->repo->index, b->path);
1806         } else {
1807                 /*
1808                  * For each destination path, we need to see if there is a
1809                  * rename/add collision.  If not, we can write the file out
1810                  * to the specified location.
1811                  */
1812                 add = filespec_from_entry(&other, ci->dst_entry1, 2 ^ 1);
1813                 if (add) {
1814                         if (handle_file_collision(o, a->path,
1815                                                   NULL, NULL,
1816                                                   ci->branch1, ci->branch2,
1817                                                   &mfi.oid, mfi.mode,
1818                                                   &add->oid, add->mode) < 0)
1819                                 return -1;
1820                 } else {
1821                         char *new_path = find_path_for_conflict(o, a->path,
1822                                                                 ci->branch1,
1823                                                                 ci->branch2);
1824                         if (update_file(o, 0, &mfi.oid, mfi.mode, new_path ? new_path : a->path))
1825                                 return -1;
1826                         free(new_path);
1827                         if (update_stages(o, a->path, NULL, a, NULL))
1828                                 return -1;
1829                 }
1830
1831                 add = filespec_from_entry(&other, ci->dst_entry2, 3 ^ 1);
1832                 if (add) {
1833                         if (handle_file_collision(o, b->path,
1834                                                   NULL, NULL,
1835                                                   ci->branch1, ci->branch2,
1836                                                   &add->oid, add->mode,
1837                                                   &mfi.oid, mfi.mode) < 0)
1838                                 return -1;
1839                 } else {
1840                         char *new_path = find_path_for_conflict(o, b->path,
1841                                                                 ci->branch2,
1842                                                                 ci->branch1);
1843                         if (update_file(o, 0, &mfi.oid, mfi.mode, new_path ? new_path : b->path))
1844                                 return -1;
1845                         free(new_path);
1846                         if (update_stages(o, b->path, NULL, NULL, b))
1847                                 return -1;
1848                 }
1849         }
1850
1851         return 0;
1852 }
1853
1854 static int handle_rename_rename_2to1(struct merge_options *o,
1855                                      struct rename_conflict_info *ci)
1856 {
1857         /* Two files, a & b, were renamed to the same thing, c. */
1858         struct diff_filespec *a = ci->pair1->one;
1859         struct diff_filespec *b = ci->pair2->one;
1860         struct diff_filespec *c1 = ci->pair1->two;
1861         struct diff_filespec *c2 = ci->pair2->two;
1862         char *path = c1->path; /* == c2->path */
1863         char *path_side_1_desc;
1864         char *path_side_2_desc;
1865         struct merge_file_info mfi_c1;
1866         struct merge_file_info mfi_c2;
1867
1868         output(o, 1, _("CONFLICT (rename/rename): "
1869                "Rename %s->%s in %s. "
1870                "Rename %s->%s in %s"),
1871                a->path, c1->path, ci->branch1,
1872                b->path, c2->path, ci->branch2);
1873
1874         path_side_1_desc = xstrfmt("version of %s from %s", path, a->path);
1875         path_side_2_desc = xstrfmt("version of %s from %s", path, b->path);
1876         if (merge_mode_and_contents(o, a, c1, &ci->ren1_other, path_side_1_desc,
1877                                     o->branch1, o->branch2,
1878                                     1 + o->call_depth * 2, &mfi_c1) ||
1879             merge_mode_and_contents(o, b, &ci->ren2_other, c2, path_side_2_desc,
1880                                     o->branch1, o->branch2,
1881                                     1 + o->call_depth * 2, &mfi_c2))
1882                 return -1;
1883         free(path_side_1_desc);
1884         free(path_side_2_desc);
1885
1886         return handle_file_collision(o, path, a->path, b->path,
1887                                      ci->branch1, ci->branch2,
1888                                      &mfi_c1.oid, mfi_c1.mode,
1889                                      &mfi_c2.oid, mfi_c2.mode);
1890 }
1891
1892 /*
1893  * Get the diff_filepairs changed between o_tree and tree.
1894  */
1895 static struct diff_queue_struct *get_diffpairs(struct merge_options *o,
1896                                                struct tree *o_tree,
1897                                                struct tree *tree)
1898 {
1899         struct diff_queue_struct *ret;
1900         struct diff_options opts;
1901
1902         repo_diff_setup(o->repo, &opts);
1903         opts.flags.recursive = 1;
1904         opts.flags.rename_empty = 0;
1905         opts.detect_rename = merge_detect_rename(o);
1906         /*
1907          * We do not have logic to handle the detection of copies.  In
1908          * fact, it may not even make sense to add such logic: would we
1909          * really want a change to a base file to be propagated through
1910          * multiple other files by a merge?
1911          */
1912         if (opts.detect_rename > DIFF_DETECT_RENAME)
1913                 opts.detect_rename = DIFF_DETECT_RENAME;
1914         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
1915                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
1916                             1000;
1917         opts.rename_score = o->rename_score;
1918         opts.show_rename_progress = o->show_rename_progress;
1919         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
1920         diff_setup_done(&opts);
1921         diff_tree_oid(&o_tree->object.oid, &tree->object.oid, "", &opts);
1922         diffcore_std(&opts);
1923         if (opts.needed_rename_limit > o->needed_rename_limit)
1924                 o->needed_rename_limit = opts.needed_rename_limit;
1925
1926         ret = xmalloc(sizeof(*ret));
1927         *ret = diff_queued_diff;
1928
1929         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
1930         diff_queued_diff.nr = 0;
1931         diff_queued_diff.queue = NULL;
1932         diff_flush(&opts);
1933         return ret;
1934 }
1935
1936 static int tree_has_path(struct tree *tree, const char *path)
1937 {
1938         struct object_id hashy;
1939         unsigned int mode_o;
1940
1941         return !get_tree_entry(&tree->object.oid, path,
1942                                &hashy, &mode_o);
1943 }
1944
1945 /*
1946  * Return a new string that replaces the beginning portion (which matches
1947  * entry->dir), with entry->new_dir.  In perl-speak:
1948  *   new_path_name = (old_path =~ s/entry->dir/entry->new_dir/);
1949  * NOTE:
1950  *   Caller must ensure that old_path starts with entry->dir + '/'.
1951  */
1952 static char *apply_dir_rename(struct dir_rename_entry *entry,
1953                               const char *old_path)
1954 {
1955         struct strbuf new_path = STRBUF_INIT;
1956         int oldlen, newlen;
1957
1958         if (entry->non_unique_new_dir)
1959                 return NULL;
1960
1961         oldlen = strlen(entry->dir);
1962         newlen = entry->new_dir.len + (strlen(old_path) - oldlen) + 1;
1963         strbuf_grow(&new_path, newlen);
1964         strbuf_addbuf(&new_path, &entry->new_dir);
1965         strbuf_addstr(&new_path, &old_path[oldlen]);
1966
1967         return strbuf_detach(&new_path, NULL);
1968 }
1969
1970 static void get_renamed_dir_portion(const char *old_path, const char *new_path,
1971                                     char **old_dir, char **new_dir)
1972 {
1973         char *end_of_old, *end_of_new;
1974         int old_len, new_len;
1975
1976         *old_dir = NULL;
1977         *new_dir = NULL;
1978
1979         /*
1980          * For
1981          *    "a/b/c/d/e/foo.c" -> "a/b/some/thing/else/e/foo.c"
1982          * the "e/foo.c" part is the same, we just want to know that
1983          *    "a/b/c/d" was renamed to "a/b/some/thing/else"
1984          * so, for this example, this function returns "a/b/c/d" in
1985          * *old_dir and "a/b/some/thing/else" in *new_dir.
1986          *
1987          * Also, if the basename of the file changed, we don't care.  We
1988          * want to know which portion of the directory, if any, changed.
1989          */
1990         end_of_old = strrchr(old_path, '/');
1991         end_of_new = strrchr(new_path, '/');
1992
1993         if (end_of_old == NULL || end_of_new == NULL)
1994                 return;
1995         while (*--end_of_new == *--end_of_old &&
1996                end_of_old != old_path &&
1997                end_of_new != new_path)
1998                 ; /* Do nothing; all in the while loop */
1999         /*
2000          * We've found the first non-matching character in the directory
2001          * paths.  That means the current directory we were comparing
2002          * represents the rename.  Move end_of_old and end_of_new back
2003          * to the full directory name.
2004          */
2005         if (*end_of_old == '/')
2006                 end_of_old++;
2007         if (*end_of_old != '/')
2008                 end_of_new++;
2009         end_of_old = strchr(end_of_old, '/');
2010         end_of_new = strchr(end_of_new, '/');
2011
2012         /*
2013          * It may have been the case that old_path and new_path were the same
2014          * directory all along.  Don't claim a rename if they're the same.
2015          */
2016         old_len = end_of_old - old_path;
2017         new_len = end_of_new - new_path;
2018
2019         if (old_len != new_len || strncmp(old_path, new_path, old_len)) {
2020                 *old_dir = xstrndup(old_path, old_len);
2021                 *new_dir = xstrndup(new_path, new_len);
2022         }
2023 }
2024
2025 static void remove_hashmap_entries(struct hashmap *dir_renames,
2026                                    struct string_list *items_to_remove)
2027 {
2028         int i;
2029         struct dir_rename_entry *entry;
2030
2031         for (i = 0; i < items_to_remove->nr; i++) {
2032                 entry = items_to_remove->items[i].util;
2033                 hashmap_remove(dir_renames, entry, NULL);
2034         }
2035         string_list_clear(items_to_remove, 0);
2036 }
2037
2038 /*
2039  * See if there is a directory rename for path, and if there are any file
2040  * level conflicts for the renamed location.  If there is a rename and
2041  * there are no conflicts, return the new name.  Otherwise, return NULL.
2042  */
2043 static char *handle_path_level_conflicts(struct merge_options *o,
2044                                          const char *path,
2045                                          struct dir_rename_entry *entry,
2046                                          struct hashmap *collisions,
2047                                          struct tree *tree)
2048 {
2049         char *new_path = NULL;
2050         struct collision_entry *collision_ent;
2051         int clean = 1;
2052         struct strbuf collision_paths = STRBUF_INIT;
2053
2054         /*
2055          * entry has the mapping of old directory name to new directory name
2056          * that we want to apply to path.
2057          */
2058         new_path = apply_dir_rename(entry, path);
2059
2060         if (!new_path) {
2061                 /* This should only happen when entry->non_unique_new_dir set */
2062                 if (!entry->non_unique_new_dir)
2063                         BUG("entry->non_unqiue_dir not set and !new_path");
2064                 output(o, 1, _("CONFLICT (directory rename split): "
2065                                "Unclear where to place %s because directory "
2066                                "%s was renamed to multiple other directories, "
2067                                "with no destination getting a majority of the "
2068                                "files."),
2069                        path, entry->dir);
2070                 clean = 0;
2071                 return NULL;
2072         }
2073
2074         /*
2075          * The caller needs to have ensured that it has pre-populated
2076          * collisions with all paths that map to new_path.  Do a quick check
2077          * to ensure that's the case.
2078          */
2079         collision_ent = collision_find_entry(collisions, new_path);
2080         if (collision_ent == NULL)
2081                 BUG("collision_ent is NULL");
2082
2083         /*
2084          * Check for one-sided add/add/.../add conflicts, i.e.
2085          * where implicit renames from the other side doing
2086          * directory rename(s) can affect this side of history
2087          * to put multiple paths into the same location.  Warn
2088          * and bail on directory renames for such paths.
2089          */
2090         if (collision_ent->reported_already) {
2091                 clean = 0;
2092         } else if (tree_has_path(tree, new_path)) {
2093                 collision_ent->reported_already = 1;
2094                 strbuf_add_separated_string_list(&collision_paths, ", ",
2095                                                  &collision_ent->source_files);
2096                 output(o, 1, _("CONFLICT (implicit dir rename): Existing "
2097                                "file/dir at %s in the way of implicit "
2098                                "directory rename(s) putting the following "
2099                                "path(s) there: %s."),
2100                        new_path, collision_paths.buf);
2101                 clean = 0;
2102         } else if (collision_ent->source_files.nr > 1) {
2103                 collision_ent->reported_already = 1;
2104                 strbuf_add_separated_string_list(&collision_paths, ", ",
2105                                                  &collision_ent->source_files);
2106                 output(o, 1, _("CONFLICT (implicit dir rename): Cannot map "
2107                                "more than one path to %s; implicit directory "
2108                                "renames tried to put these paths there: %s"),
2109                        new_path, collision_paths.buf);
2110                 clean = 0;
2111         }
2112
2113         /* Free memory we no longer need */
2114         strbuf_release(&collision_paths);
2115         if (!clean && new_path) {
2116                 free(new_path);
2117                 return NULL;
2118         }
2119
2120         return new_path;
2121 }
2122
2123 /*
2124  * There are a couple things we want to do at the directory level:
2125  *   1. Check for both sides renaming to the same thing, in order to avoid
2126  *      implicit renaming of files that should be left in place.  (See
2127  *      testcase 6b in t6043 for details.)
2128  *   2. Prune directory renames if there are still files left in the
2129  *      the original directory.  These represent a partial directory rename,
2130  *      i.e. a rename where only some of the files within the directory
2131  *      were renamed elsewhere.  (Technically, this could be done earlier
2132  *      in get_directory_renames(), except that would prevent us from
2133  *      doing the previous check and thus failing testcase 6b.)
2134  *   3. Check for rename/rename(1to2) conflicts (at the directory level).
2135  *      In the future, we could potentially record this info as well and
2136  *      omit reporting rename/rename(1to2) conflicts for each path within
2137  *      the affected directories, thus cleaning up the merge output.
2138  *   NOTE: We do NOT check for rename/rename(2to1) conflicts at the
2139  *         directory level, because merging directories is fine.  If it
2140  *         causes conflicts for files within those merged directories, then
2141  *         that should be detected at the individual path level.
2142  */
2143 static void handle_directory_level_conflicts(struct merge_options *o,
2144                                              struct hashmap *dir_re_head,
2145                                              struct tree *head,
2146                                              struct hashmap *dir_re_merge,
2147                                              struct tree *merge)
2148 {
2149         struct hashmap_iter iter;
2150         struct dir_rename_entry *head_ent;
2151         struct dir_rename_entry *merge_ent;
2152
2153         struct string_list remove_from_head = STRING_LIST_INIT_NODUP;
2154         struct string_list remove_from_merge = STRING_LIST_INIT_NODUP;
2155
2156         hashmap_iter_init(dir_re_head, &iter);
2157         while ((head_ent = hashmap_iter_next(&iter))) {
2158                 merge_ent = dir_rename_find_entry(dir_re_merge, head_ent->dir);
2159                 if (merge_ent &&
2160                     !head_ent->non_unique_new_dir &&
2161                     !merge_ent->non_unique_new_dir &&
2162                     !strbuf_cmp(&head_ent->new_dir, &merge_ent->new_dir)) {
2163                         /* 1. Renamed identically; remove it from both sides */
2164                         string_list_append(&remove_from_head,
2165                                            head_ent->dir)->util = head_ent;
2166                         strbuf_release(&head_ent->new_dir);
2167                         string_list_append(&remove_from_merge,
2168                                            merge_ent->dir)->util = merge_ent;
2169                         strbuf_release(&merge_ent->new_dir);
2170                 } else if (tree_has_path(head, head_ent->dir)) {
2171                         /* 2. This wasn't a directory rename after all */
2172                         string_list_append(&remove_from_head,
2173                                            head_ent->dir)->util = head_ent;
2174                         strbuf_release(&head_ent->new_dir);
2175                 }
2176         }
2177
2178         remove_hashmap_entries(dir_re_head, &remove_from_head);
2179         remove_hashmap_entries(dir_re_merge, &remove_from_merge);
2180
2181         hashmap_iter_init(dir_re_merge, &iter);
2182         while ((merge_ent = hashmap_iter_next(&iter))) {
2183                 head_ent = dir_rename_find_entry(dir_re_head, merge_ent->dir);
2184                 if (tree_has_path(merge, merge_ent->dir)) {
2185                         /* 2. This wasn't a directory rename after all */
2186                         string_list_append(&remove_from_merge,
2187                                            merge_ent->dir)->util = merge_ent;
2188                 } else if (head_ent &&
2189                            !head_ent->non_unique_new_dir &&
2190                            !merge_ent->non_unique_new_dir) {
2191                         /* 3. rename/rename(1to2) */
2192                         /*
2193                          * We can assume it's not rename/rename(1to1) because
2194                          * that was case (1), already checked above.  So we
2195                          * know that head_ent->new_dir and merge_ent->new_dir
2196                          * are different strings.
2197                          */
2198                         output(o, 1, _("CONFLICT (rename/rename): "
2199                                        "Rename directory %s->%s in %s. "
2200                                        "Rename directory %s->%s in %s"),
2201                                head_ent->dir, head_ent->new_dir.buf, o->branch1,
2202                                head_ent->dir, merge_ent->new_dir.buf, o->branch2);
2203                         string_list_append(&remove_from_head,
2204                                            head_ent->dir)->util = head_ent;
2205                         strbuf_release(&head_ent->new_dir);
2206                         string_list_append(&remove_from_merge,
2207                                            merge_ent->dir)->util = merge_ent;
2208                         strbuf_release(&merge_ent->new_dir);
2209                 }
2210         }
2211
2212         remove_hashmap_entries(dir_re_head, &remove_from_head);
2213         remove_hashmap_entries(dir_re_merge, &remove_from_merge);
2214 }
2215
2216 static struct hashmap *get_directory_renames(struct diff_queue_struct *pairs,
2217                                              struct tree *tree)
2218 {
2219         struct hashmap *dir_renames;
2220         struct hashmap_iter iter;
2221         struct dir_rename_entry *entry;
2222         int i;
2223
2224         /*
2225          * Typically, we think of a directory rename as all files from a
2226          * certain directory being moved to a target directory.  However,
2227          * what if someone first moved two files from the original
2228          * directory in one commit, and then renamed the directory
2229          * somewhere else in a later commit?  At merge time, we just know
2230          * that files from the original directory went to two different
2231          * places, and that the bulk of them ended up in the same place.
2232          * We want each directory rename to represent where the bulk of the
2233          * files from that directory end up; this function exists to find
2234          * where the bulk of the files went.
2235          *
2236          * The first loop below simply iterates through the list of file
2237          * renames, finding out how often each directory rename pair
2238          * possibility occurs.
2239          */
2240         dir_renames = xmalloc(sizeof(*dir_renames));
2241         dir_rename_init(dir_renames);
2242         for (i = 0; i < pairs->nr; ++i) {
2243                 struct string_list_item *item;
2244                 int *count;
2245                 struct diff_filepair *pair = pairs->queue[i];
2246                 char *old_dir, *new_dir;
2247
2248                 /* File not part of directory rename if it wasn't renamed */
2249                 if (pair->status != 'R')
2250                         continue;
2251
2252                 get_renamed_dir_portion(pair->one->path, pair->two->path,
2253                                         &old_dir,        &new_dir);
2254                 if (!old_dir)
2255                         /* Directory didn't change at all; ignore this one. */
2256                         continue;
2257
2258                 entry = dir_rename_find_entry(dir_renames, old_dir);
2259                 if (!entry) {
2260                         entry = xmalloc(sizeof(*entry));
2261                         dir_rename_entry_init(entry, old_dir);
2262                         hashmap_put(dir_renames, entry);
2263                 } else {
2264                         free(old_dir);
2265                 }
2266                 item = string_list_lookup(&entry->possible_new_dirs, new_dir);
2267                 if (!item) {
2268                         item = string_list_insert(&entry->possible_new_dirs,
2269                                                   new_dir);
2270                         item->util = xcalloc(1, sizeof(int));
2271                 } else {
2272                         free(new_dir);
2273                 }
2274                 count = item->util;
2275                 *count += 1;
2276         }
2277
2278         /*
2279          * For each directory with files moved out of it, we find out which
2280          * target directory received the most files so we can declare it to
2281          * be the "winning" target location for the directory rename.  This
2282          * winner gets recorded in new_dir.  If there is no winner
2283          * (multiple target directories received the same number of files),
2284          * we set non_unique_new_dir.  Once we've determined the winner (or
2285          * that there is no winner), we no longer need possible_new_dirs.
2286          */
2287         hashmap_iter_init(dir_renames, &iter);
2288         while ((entry = hashmap_iter_next(&iter))) {
2289                 int max = 0;
2290                 int bad_max = 0;
2291                 char *best = NULL;
2292
2293                 for (i = 0; i < entry->possible_new_dirs.nr; i++) {
2294                         int *count = entry->possible_new_dirs.items[i].util;
2295
2296                         if (*count == max)
2297                                 bad_max = max;
2298                         else if (*count > max) {
2299                                 max = *count;
2300                                 best = entry->possible_new_dirs.items[i].string;
2301                         }
2302                 }
2303                 if (bad_max == max)
2304                         entry->non_unique_new_dir = 1;
2305                 else {
2306                         assert(entry->new_dir.len == 0);
2307                         strbuf_addstr(&entry->new_dir, best);
2308                 }
2309                 /*
2310                  * The relevant directory sub-portion of the original full
2311                  * filepaths were xstrndup'ed before inserting into
2312                  * possible_new_dirs, and instead of manually iterating the
2313                  * list and free'ing each, just lie and tell
2314                  * possible_new_dirs that it did the strdup'ing so that it
2315                  * will free them for us.
2316                  */
2317                 entry->possible_new_dirs.strdup_strings = 1;
2318                 string_list_clear(&entry->possible_new_dirs, 1);
2319         }
2320
2321         return dir_renames;
2322 }
2323
2324 static struct dir_rename_entry *check_dir_renamed(const char *path,
2325                                                   struct hashmap *dir_renames)
2326 {
2327         char *temp = xstrdup(path);
2328         char *end;
2329         struct dir_rename_entry *entry = NULL;
2330
2331         while ((end = strrchr(temp, '/'))) {
2332                 *end = '\0';
2333                 entry = dir_rename_find_entry(dir_renames, temp);
2334                 if (entry)
2335                         break;
2336         }
2337         free(temp);
2338         return entry;
2339 }
2340
2341 static void compute_collisions(struct hashmap *collisions,
2342                                struct hashmap *dir_renames,
2343                                struct diff_queue_struct *pairs)
2344 {
2345         int i;
2346
2347         /*
2348          * Multiple files can be mapped to the same path due to directory
2349          * renames done by the other side of history.  Since that other
2350          * side of history could have merged multiple directories into one,
2351          * if our side of history added the same file basename to each of
2352          * those directories, then all N of them would get implicitly
2353          * renamed by the directory rename detection into the same path,
2354          * and we'd get an add/add/.../add conflict, and all those adds
2355          * from *this* side of history.  This is not representable in the
2356          * index, and users aren't going to easily be able to make sense of
2357          * it.  So we need to provide a good warning about what's
2358          * happening, and fall back to no-directory-rename detection
2359          * behavior for those paths.
2360          *
2361          * See testcases 9e and all of section 5 from t6043 for examples.
2362          */
2363         collision_init(collisions);
2364
2365         for (i = 0; i < pairs->nr; ++i) {
2366                 struct dir_rename_entry *dir_rename_ent;
2367                 struct collision_entry *collision_ent;
2368                 char *new_path;
2369                 struct diff_filepair *pair = pairs->queue[i];
2370
2371                 if (pair->status != 'A' && pair->status != 'R')
2372                         continue;
2373                 dir_rename_ent = check_dir_renamed(pair->two->path,
2374                                                    dir_renames);
2375                 if (!dir_rename_ent)
2376                         continue;
2377
2378                 new_path = apply_dir_rename(dir_rename_ent, pair->two->path);
2379                 if (!new_path)
2380                         /*
2381                          * dir_rename_ent->non_unique_new_path is true, which
2382                          * means there is no directory rename for us to use,
2383                          * which means it won't cause us any additional
2384                          * collisions.
2385                          */
2386                         continue;
2387                 collision_ent = collision_find_entry(collisions, new_path);
2388                 if (!collision_ent) {
2389                         collision_ent = xcalloc(1,
2390                                                 sizeof(struct collision_entry));
2391                         hashmap_entry_init(collision_ent, strhash(new_path));
2392                         hashmap_put(collisions, collision_ent);
2393                         collision_ent->target_file = new_path;
2394                 } else {
2395                         free(new_path);
2396                 }
2397                 string_list_insert(&collision_ent->source_files,
2398                                    pair->two->path);
2399         }
2400 }
2401
2402 static char *check_for_directory_rename(struct merge_options *o,
2403                                         const char *path,
2404                                         struct tree *tree,
2405                                         struct hashmap *dir_renames,
2406                                         struct hashmap *dir_rename_exclusions,
2407                                         struct hashmap *collisions,
2408                                         int *clean_merge)
2409 {
2410         char *new_path = NULL;
2411         struct dir_rename_entry *entry = check_dir_renamed(path, dir_renames);
2412         struct dir_rename_entry *oentry = NULL;
2413
2414         if (!entry)
2415                 return new_path;
2416
2417         /*
2418          * This next part is a little weird.  We do not want to do an
2419          * implicit rename into a directory we renamed on our side, because
2420          * that will result in a spurious rename/rename(1to2) conflict.  An
2421          * example:
2422          *   Base commit: dumbdir/afile, otherdir/bfile
2423          *   Side 1:      smrtdir/afile, otherdir/bfile
2424          *   Side 2:      dumbdir/afile, dumbdir/bfile
2425          * Here, while working on Side 1, we could notice that otherdir was
2426          * renamed/merged to dumbdir, and change the diff_filepair for
2427          * otherdir/bfile into a rename into dumbdir/bfile.  However, Side
2428          * 2 will notice the rename from dumbdir to smrtdir, and do the
2429          * transitive rename to move it from dumbdir/bfile to
2430          * smrtdir/bfile.  That gives us bfile in dumbdir vs being in
2431          * smrtdir, a rename/rename(1to2) conflict.  We really just want
2432          * the file to end up in smrtdir.  And the way to achieve that is
2433          * to not let Side1 do the rename to dumbdir, since we know that is
2434          * the source of one of our directory renames.
2435          *
2436          * That's why oentry and dir_rename_exclusions is here.
2437          *
2438          * As it turns out, this also prevents N-way transient rename
2439          * confusion; See testcases 9c and 9d of t6043.
2440          */
2441         oentry = dir_rename_find_entry(dir_rename_exclusions, entry->new_dir.buf);
2442         if (oentry) {
2443                 output(o, 1, _("WARNING: Avoiding applying %s -> %s rename "
2444                                "to %s, because %s itself was renamed."),
2445                        entry->dir, entry->new_dir.buf, path, entry->new_dir.buf);
2446         } else {
2447                 new_path = handle_path_level_conflicts(o, path, entry,
2448                                                        collisions, tree);
2449                 *clean_merge &= (new_path != NULL);
2450         }
2451
2452         return new_path;
2453 }
2454
2455 static void apply_directory_rename_modifications(struct merge_options *o,
2456                                                  struct diff_filepair *pair,
2457                                                  char *new_path,
2458                                                  struct rename *re,
2459                                                  struct tree *tree,
2460                                                  struct tree *o_tree,
2461                                                  struct tree *a_tree,
2462                                                  struct tree *b_tree,
2463                                                  struct string_list *entries,
2464                                                  int *clean)
2465 {
2466         struct string_list_item *item;
2467         int stage = (tree == a_tree ? 2 : 3);
2468         int update_wd;
2469
2470         /*
2471          * In all cases where we can do directory rename detection,
2472          * unpack_trees() will have read pair->two->path into the
2473          * index and the working copy.  We need to remove it so that
2474          * we can instead place it at new_path.  It is guaranteed to
2475          * not be untracked (unpack_trees() would have errored out
2476          * saying the file would have been overwritten), but it might
2477          * be dirty, though.
2478          */
2479         update_wd = !was_dirty(o, pair->two->path);
2480         if (!update_wd)
2481                 output(o, 1, _("Refusing to lose dirty file at %s"),
2482                        pair->two->path);
2483         remove_file(o, 1, pair->two->path, !update_wd);
2484
2485         /* Find or create a new re->dst_entry */
2486         item = string_list_lookup(entries, new_path);
2487         if (item) {
2488                 /*
2489                  * Since we're renaming on this side of history, and it's
2490                  * due to a directory rename on the other side of history
2491                  * (which we only allow when the directory in question no
2492                  * longer exists on the other side of history), the
2493                  * original entry for re->dst_entry is no longer
2494                  * necessary...
2495                  */
2496                 re->dst_entry->processed = 1;
2497
2498                 /*
2499                  * ...because we'll be using this new one.
2500                  */
2501                 re->dst_entry = item->util;
2502         } else {
2503                 /*
2504                  * re->dst_entry is for the before-dir-rename path, and we
2505                  * need it to hold information for the after-dir-rename
2506                  * path.  Before creating a new entry, we need to mark the
2507                  * old one as unnecessary (...unless it is shared by
2508                  * src_entry, i.e. this didn't use to be a rename, in which
2509                  * case we can just allow the normal processing to happen
2510                  * for it).
2511                  */
2512                 if (pair->status == 'R')
2513                         re->dst_entry->processed = 1;
2514
2515                 re->dst_entry = insert_stage_data(new_path,
2516                                                   o_tree, a_tree, b_tree,
2517                                                   entries);
2518                 item = string_list_insert(entries, new_path);
2519                 item->util = re->dst_entry;
2520         }
2521
2522         /*
2523          * Update the stage_data with the information about the path we are
2524          * moving into place.  That slot will be empty and available for us
2525          * to write to because of the collision checks in
2526          * handle_path_level_conflicts().  In other words,
2527          * re->dst_entry->stages[stage].oid will be the null_oid, so it's
2528          * open for us to write to.
2529          *
2530          * It may be tempting to actually update the index at this point as
2531          * well, using update_stages_for_stage_data(), but as per the big
2532          * "NOTE" in update_stages(), doing so will modify the current
2533          * in-memory index which will break calls to would_lose_untracked()
2534          * that we need to make.  Instead, we need to just make sure that
2535          * the various handle_rename_*() functions update the index
2536          * explicitly rather than relying on unpack_trees() to have done it.
2537          */
2538         get_tree_entry(&tree->object.oid,
2539                        pair->two->path,
2540                        &re->dst_entry->stages[stage].oid,
2541                        &re->dst_entry->stages[stage].mode);
2542
2543         /* Update pair status */
2544         if (pair->status == 'A') {
2545                 /*
2546                  * Recording rename information for this add makes it look
2547                  * like a rename/delete conflict.  Make sure we can
2548                  * correctly handle this as an add that was moved to a new
2549                  * directory instead of reporting a rename/delete conflict.
2550                  */
2551                 re->add_turned_into_rename = 1;
2552         }
2553         /*
2554          * We don't actually look at pair->status again, but it seems
2555          * pedagogically correct to adjust it.
2556          */
2557         pair->status = 'R';
2558
2559         /*
2560          * Finally, record the new location.
2561          */
2562         pair->two->path = new_path;
2563 }
2564
2565 /*
2566  * Get information of all renames which occurred in 'pairs', making use of
2567  * any implicit directory renames inferred from the other side of history.
2568  * We need the three trees in the merge ('o_tree', 'a_tree' and 'b_tree')
2569  * to be able to associate the correct cache entries with the rename
2570  * information; tree is always equal to either a_tree or b_tree.
2571  */
2572 static struct string_list *get_renames(struct merge_options *o,
2573                                        struct diff_queue_struct *pairs,
2574                                        struct hashmap *dir_renames,
2575                                        struct hashmap *dir_rename_exclusions,
2576                                        struct tree *tree,
2577                                        struct tree *o_tree,
2578                                        struct tree *a_tree,
2579                                        struct tree *b_tree,
2580                                        struct string_list *entries,
2581                                        int *clean_merge)
2582 {
2583         int i;
2584         struct hashmap collisions;
2585         struct hashmap_iter iter;
2586         struct collision_entry *e;
2587         struct string_list *renames;
2588
2589         compute_collisions(&collisions, dir_renames, pairs);
2590         renames = xcalloc(1, sizeof(struct string_list));
2591
2592         for (i = 0; i < pairs->nr; ++i) {
2593                 struct string_list_item *item;
2594                 struct rename *re;
2595                 struct diff_filepair *pair = pairs->queue[i];
2596                 char *new_path; /* non-NULL only with directory renames */
2597
2598                 if (pair->status != 'A' && pair->status != 'R') {
2599                         diff_free_filepair(pair);
2600                         continue;
2601                 }
2602                 new_path = check_for_directory_rename(o, pair->two->path, tree,
2603                                                       dir_renames,
2604                                                       dir_rename_exclusions,
2605                                                       &collisions,
2606                                                       clean_merge);
2607                 if (pair->status != 'R' && !new_path) {
2608                         diff_free_filepair(pair);
2609                         continue;
2610                 }
2611
2612                 re = xmalloc(sizeof(*re));
2613                 re->processed = 0;
2614                 re->add_turned_into_rename = 0;
2615                 re->pair = pair;
2616                 item = string_list_lookup(entries, re->pair->one->path);
2617                 if (!item)
2618                         re->src_entry = insert_stage_data(re->pair->one->path,
2619                                         o_tree, a_tree, b_tree, entries);
2620                 else
2621                         re->src_entry = item->util;
2622
2623                 item = string_list_lookup(entries, re->pair->two->path);
2624                 if (!item)
2625                         re->dst_entry = insert_stage_data(re->pair->two->path,
2626                                         o_tree, a_tree, b_tree, entries);
2627                 else
2628                         re->dst_entry = item->util;
2629                 item = string_list_insert(renames, pair->one->path);
2630                 item->util = re;
2631                 if (new_path)
2632                         apply_directory_rename_modifications(o, pair, new_path,
2633                                                              re, tree, o_tree,
2634                                                              a_tree, b_tree,
2635                                                              entries,
2636                                                              clean_merge);
2637         }
2638
2639         hashmap_iter_init(&collisions, &iter);
2640         while ((e = hashmap_iter_next(&iter))) {
2641                 free(e->target_file);
2642                 string_list_clear(&e->source_files, 0);
2643         }
2644         hashmap_free(&collisions, 1);
2645         return renames;
2646 }
2647
2648 static int process_renames(struct merge_options *o,
2649                            struct string_list *a_renames,
2650                            struct string_list *b_renames)
2651 {
2652         int clean_merge = 1, i, j;
2653         struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
2654         struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
2655         const struct rename *sre;
2656
2657         for (i = 0; i < a_renames->nr; i++) {
2658                 sre = a_renames->items[i].util;
2659                 string_list_insert(&a_by_dst, sre->pair->two->path)->util
2660                         = (void *)sre;
2661         }
2662         for (i = 0; i < b_renames->nr; i++) {
2663                 sre = b_renames->items[i].util;
2664                 string_list_insert(&b_by_dst, sre->pair->two->path)->util
2665                         = (void *)sre;
2666         }
2667
2668         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
2669                 struct string_list *renames1, *renames2Dst;
2670                 struct rename *ren1 = NULL, *ren2 = NULL;
2671                 const char *branch1, *branch2;
2672                 const char *ren1_src, *ren1_dst;
2673                 struct string_list_item *lookup;
2674
2675                 if (i >= a_renames->nr) {
2676                         ren2 = b_renames->items[j++].util;
2677                 } else if (j >= b_renames->nr) {
2678                         ren1 = a_renames->items[i++].util;
2679                 } else {
2680                         int compare = strcmp(a_renames->items[i].string,
2681                                              b_renames->items[j].string);
2682                         if (compare <= 0)
2683                                 ren1 = a_renames->items[i++].util;
2684                         if (compare >= 0)
2685                                 ren2 = b_renames->items[j++].util;
2686                 }
2687
2688                 /* TODO: refactor, so that 1/2 are not needed */
2689                 if (ren1) {
2690                         renames1 = a_renames;
2691                         renames2Dst = &b_by_dst;
2692                         branch1 = o->branch1;
2693                         branch2 = o->branch2;
2694                 } else {
2695                         renames1 = b_renames;
2696                         renames2Dst = &a_by_dst;
2697                         branch1 = o->branch2;
2698                         branch2 = o->branch1;
2699                         SWAP(ren2, ren1);
2700                 }
2701
2702                 if (ren1->processed)
2703                         continue;
2704                 ren1->processed = 1;
2705                 ren1->dst_entry->processed = 1;
2706                 /* BUG: We should only mark src_entry as processed if we
2707                  * are not dealing with a rename + add-source case.
2708                  */
2709                 ren1->src_entry->processed = 1;
2710
2711                 ren1_src = ren1->pair->one->path;
2712                 ren1_dst = ren1->pair->two->path;
2713
2714                 if (ren2) {
2715                         /* One file renamed on both sides */
2716                         const char *ren2_src = ren2->pair->one->path;
2717                         const char *ren2_dst = ren2->pair->two->path;
2718                         enum rename_type rename_type;
2719                         if (strcmp(ren1_src, ren2_src) != 0)
2720                                 BUG("ren1_src != ren2_src");
2721                         ren2->dst_entry->processed = 1;
2722                         ren2->processed = 1;
2723                         if (strcmp(ren1_dst, ren2_dst) != 0) {
2724                                 rename_type = RENAME_ONE_FILE_TO_TWO;
2725                                 clean_merge = 0;
2726                         } else {
2727                                 rename_type = RENAME_ONE_FILE_TO_ONE;
2728                                 /* BUG: We should only remove ren1_src in
2729                                  * the base stage (think of rename +
2730                                  * add-source cases).
2731                                  */
2732                                 remove_file(o, 1, ren1_src, 1);
2733                                 update_entry(ren1->dst_entry,
2734                                              ren1->pair->one,
2735                                              ren1->pair->two,
2736                                              ren2->pair->two);
2737                         }
2738                         setup_rename_conflict_info(rename_type,
2739                                                    ren1->pair,
2740                                                    ren2->pair,
2741                                                    branch1,
2742                                                    branch2,
2743                                                    ren1->dst_entry,
2744                                                    ren2->dst_entry,
2745                                                    o,
2746                                                    NULL,
2747                                                    NULL);
2748                 } else if ((lookup = string_list_lookup(renames2Dst, ren1_dst))) {
2749                         /* Two different files renamed to the same thing */
2750                         char *ren2_dst;
2751                         ren2 = lookup->util;
2752                         ren2_dst = ren2->pair->two->path;
2753                         if (strcmp(ren1_dst, ren2_dst) != 0)
2754                                 BUG("ren1_dst != ren2_dst");
2755
2756                         clean_merge = 0;
2757                         ren2->processed = 1;
2758                         /*
2759                          * BUG: We should only mark src_entry as processed
2760                          * if we are not dealing with a rename + add-source
2761                          * case.
2762                          */
2763                         ren2->src_entry->processed = 1;
2764
2765                         setup_rename_conflict_info(RENAME_TWO_FILES_TO_ONE,
2766                                                    ren1->pair,
2767                                                    ren2->pair,
2768                                                    branch1,
2769                                                    branch2,
2770                                                    ren1->dst_entry,
2771                                                    ren2->dst_entry,
2772                                                    o,
2773                                                    ren1->src_entry,
2774                                                    ren2->src_entry);
2775
2776                 } else {
2777                         /* Renamed in 1, maybe changed in 2 */
2778                         /* we only use sha1 and mode of these */
2779                         struct diff_filespec src_other, dst_other;
2780                         int try_merge;
2781
2782                         /*
2783                          * unpack_trees loads entries from common-commit
2784                          * into stage 1, from head-commit into stage 2, and
2785                          * from merge-commit into stage 3.  We keep track
2786                          * of which side corresponds to the rename.
2787                          */
2788                         int renamed_stage = a_renames == renames1 ? 2 : 3;
2789                         int other_stage =   a_renames == renames1 ? 3 : 2;
2790
2791                         /* BUG: We should only remove ren1_src in the base
2792                          * stage and in other_stage (think of rename +
2793                          * add-source case).
2794                          */
2795                         remove_file(o, 1, ren1_src,
2796                                     renamed_stage == 2 || !was_tracked(o, ren1_src));
2797
2798                         oidcpy(&src_other.oid,
2799                                &ren1->src_entry->stages[other_stage].oid);
2800                         src_other.mode = ren1->src_entry->stages[other_stage].mode;
2801                         oidcpy(&dst_other.oid,
2802                                &ren1->dst_entry->stages[other_stage].oid);
2803                         dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
2804                         try_merge = 0;
2805
2806                         if (oid_eq(&src_other.oid, &null_oid) &&
2807                             ren1->add_turned_into_rename) {
2808                                 setup_rename_conflict_info(RENAME_VIA_DIR,
2809                                                            ren1->pair,
2810                                                            NULL,
2811                                                            branch1,
2812                                                            branch2,
2813                                                            ren1->dst_entry,
2814                                                            NULL,
2815                                                            o,
2816                                                            NULL,
2817                                                            NULL);
2818                         } else if (oid_eq(&src_other.oid, &null_oid)) {
2819                                 setup_rename_conflict_info(RENAME_DELETE,
2820                                                            ren1->pair,
2821                                                            NULL,
2822                                                            branch1,
2823                                                            branch2,
2824                                                            ren1->dst_entry,
2825                                                            NULL,
2826                                                            o,
2827                                                            NULL,
2828                                                            NULL);
2829                         } else if ((dst_other.mode == ren1->pair->two->mode) &&
2830                                    oid_eq(&dst_other.oid, &ren1->pair->two->oid)) {
2831                                 /*
2832                                  * Added file on the other side identical to
2833                                  * the file being renamed: clean merge.
2834                                  * Also, there is no need to overwrite the
2835                                  * file already in the working copy, so call
2836                                  * update_file_flags() instead of
2837                                  * update_file().
2838                                  */
2839                                 if (update_file_flags(o,
2840                                                       &ren1->pair->two->oid,
2841                                                       ren1->pair->two->mode,
2842                                                       ren1_dst,
2843                                                       1, /* update_cache */
2844                                                       0  /* update_wd    */))
2845                                         clean_merge = -1;
2846                         } else if (!oid_eq(&dst_other.oid, &null_oid)) {
2847                                 /*
2848                                  * Probably not a clean merge, but it's
2849                                  * premature to set clean_merge to 0 here,
2850                                  * because if the rename merges cleanly and
2851                                  * the merge exactly matches the newly added
2852                                  * file, then the merge will be clean.
2853                                  */
2854                                 setup_rename_conflict_info(RENAME_ADD,
2855                                                            ren1->pair,
2856                                                            NULL,
2857                                                            branch1,
2858                                                            branch2,
2859                                                            ren1->dst_entry,
2860                                                            NULL,
2861                                                            o,
2862                                                            ren1->src_entry,
2863                                                            NULL);
2864                         } else
2865                                 try_merge = 1;
2866
2867                         if (clean_merge < 0)
2868                                 goto cleanup_and_return;
2869                         if (try_merge) {
2870                                 struct diff_filespec *one, *a, *b;
2871                                 src_other.path = (char *)ren1_src;
2872
2873                                 one = ren1->pair->one;
2874                                 if (a_renames == renames1) {
2875                                         a = ren1->pair->two;
2876                                         b = &src_other;
2877                                 } else {
2878                                         b = ren1->pair->two;
2879                                         a = &src_other;
2880                                 }
2881                                 update_entry(ren1->dst_entry, one, a, b);
2882                                 setup_rename_conflict_info(RENAME_NORMAL,
2883                                                            ren1->pair,
2884                                                            NULL,
2885                                                            branch1,
2886                                                            NULL,
2887                                                            ren1->dst_entry,
2888                                                            NULL,
2889                                                            o,
2890                                                            NULL,
2891                                                            NULL);
2892                         }
2893                 }
2894         }
2895 cleanup_and_return:
2896         string_list_clear(&a_by_dst, 0);
2897         string_list_clear(&b_by_dst, 0);
2898
2899         return clean_merge;
2900 }
2901
2902 struct rename_info {
2903         struct string_list *head_renames;
2904         struct string_list *merge_renames;
2905 };
2906
2907 static void initial_cleanup_rename(struct diff_queue_struct *pairs,
2908                                    struct hashmap *dir_renames)
2909 {
2910         struct hashmap_iter iter;
2911         struct dir_rename_entry *e;
2912
2913         hashmap_iter_init(dir_renames, &iter);
2914         while ((e = hashmap_iter_next(&iter))) {
2915                 free(e->dir);
2916                 strbuf_release(&e->new_dir);
2917                 /* possible_new_dirs already cleared in get_directory_renames */
2918         }
2919         hashmap_free(dir_renames, 1);
2920         free(dir_renames);
2921
2922         free(pairs->queue);
2923         free(pairs);
2924 }
2925
2926 static int detect_and_process_renames(struct merge_options *o,
2927                                       struct tree *common,
2928                                       struct tree *head,
2929                                       struct tree *merge,
2930                                       struct string_list *entries,
2931                                       struct rename_info *ri)
2932 {
2933         struct diff_queue_struct *head_pairs, *merge_pairs;
2934         struct hashmap *dir_re_head, *dir_re_merge;
2935         int clean = 1;
2936
2937         ri->head_renames = NULL;
2938         ri->merge_renames = NULL;
2939
2940         if (!merge_detect_rename(o))
2941                 return 1;
2942
2943         head_pairs = get_diffpairs(o, common, head);
2944         merge_pairs = get_diffpairs(o, common, merge);
2945
2946         if (o->detect_directory_renames) {
2947                 dir_re_head = get_directory_renames(head_pairs, head);
2948                 dir_re_merge = get_directory_renames(merge_pairs, merge);
2949
2950                 handle_directory_level_conflicts(o,
2951                                                  dir_re_head, head,
2952                                                  dir_re_merge, merge);
2953         } else {
2954                 dir_re_head  = xmalloc(sizeof(*dir_re_head));
2955                 dir_re_merge = xmalloc(sizeof(*dir_re_merge));
2956                 dir_rename_init(dir_re_head);
2957                 dir_rename_init(dir_re_merge);
2958         }
2959
2960         ri->head_renames  = get_renames(o, head_pairs,
2961                                         dir_re_merge, dir_re_head, head,
2962                                         common, head, merge, entries,
2963                                         &clean);
2964         if (clean < 0)
2965                 goto cleanup;
2966         ri->merge_renames = get_renames(o, merge_pairs,
2967                                         dir_re_head, dir_re_merge, merge,
2968                                         common, head, merge, entries,
2969                                         &clean);
2970         if (clean < 0)
2971                 goto cleanup;
2972         clean &= process_renames(o, ri->head_renames, ri->merge_renames);
2973
2974 cleanup:
2975         /*
2976          * Some cleanup is deferred until cleanup_renames() because the
2977          * data structures are still needed and referenced in
2978          * process_entry().  But there are a few things we can free now.
2979          */
2980         initial_cleanup_rename(head_pairs, dir_re_head);
2981         initial_cleanup_rename(merge_pairs, dir_re_merge);
2982
2983         return clean;
2984 }
2985
2986 static void final_cleanup_rename(struct string_list *rename)
2987 {
2988         const struct rename *re;
2989         int i;
2990
2991         if (rename == NULL)
2992                 return;
2993
2994         for (i = 0; i < rename->nr; i++) {
2995                 re = rename->items[i].util;
2996                 diff_free_filepair(re->pair);
2997         }
2998         string_list_clear(rename, 1);
2999         free(rename);
3000 }
3001
3002 static void final_cleanup_renames(struct rename_info *re_info)
3003 {
3004         final_cleanup_rename(re_info->head_renames);
3005         final_cleanup_rename(re_info->merge_renames);
3006 }
3007
3008 static struct object_id *stage_oid(const struct object_id *oid, unsigned mode)
3009 {
3010         return (is_null_oid(oid) || mode == 0) ? NULL: (struct object_id *)oid;
3011 }
3012
3013 static int read_oid_strbuf(struct merge_options *o,
3014                            const struct object_id *oid,
3015                            struct strbuf *dst)
3016 {
3017         void *buf;
3018         enum object_type type;
3019         unsigned long size;
3020         buf = read_object_file(oid, &type, &size);
3021         if (!buf)
3022                 return err(o, _("cannot read object %s"), oid_to_hex(oid));
3023         if (type != OBJ_BLOB) {
3024                 free(buf);
3025                 return err(o, _("object %s is not a blob"), oid_to_hex(oid));
3026         }
3027         strbuf_attach(dst, buf, size, size + 1);
3028         return 0;
3029 }
3030
3031 static int blob_unchanged(struct merge_options *opt,
3032                           const struct object_id *o_oid,
3033                           unsigned o_mode,
3034                           const struct object_id *a_oid,
3035                           unsigned a_mode,
3036                           int renormalize, const char *path)
3037 {
3038         struct strbuf o = STRBUF_INIT;
3039         struct strbuf a = STRBUF_INIT;
3040         int ret = 0; /* assume changed for safety */
3041
3042         if (a_mode != o_mode)
3043                 return 0;
3044         if (oid_eq(o_oid, a_oid))
3045                 return 1;
3046         if (!renormalize)
3047                 return 0;
3048
3049         assert(o_oid && a_oid);
3050         if (read_oid_strbuf(opt, o_oid, &o) || read_oid_strbuf(opt, a_oid, &a))
3051                 goto error_return;
3052         /*
3053          * Note: binary | is used so that both renormalizations are
3054          * performed.  Comparison can be skipped if both files are
3055          * unchanged since their sha1s have already been compared.
3056          */
3057         if (renormalize_buffer(opt->repo->index, path, o.buf, o.len, &o) |
3058             renormalize_buffer(opt->repo->index, path, a.buf, a.len, &a))
3059                 ret = (o.len == a.len && !memcmp(o.buf, a.buf, o.len));
3060
3061 error_return:
3062         strbuf_release(&o);
3063         strbuf_release(&a);
3064         return ret;
3065 }
3066
3067 static int handle_modify_delete(struct merge_options *o,
3068                                 const char *path,
3069                                 struct object_id *o_oid, int o_mode,
3070                                 struct object_id *a_oid, int a_mode,
3071                                 struct object_id *b_oid, int b_mode)
3072 {
3073         const char *modify_branch, *delete_branch;
3074         struct object_id *changed_oid;
3075         int changed_mode;
3076
3077         if (a_oid) {
3078                 modify_branch = o->branch1;
3079                 delete_branch = o->branch2;
3080                 changed_oid = a_oid;
3081                 changed_mode = a_mode;
3082         } else {
3083                 modify_branch = o->branch2;
3084                 delete_branch = o->branch1;
3085                 changed_oid = b_oid;
3086                 changed_mode = b_mode;
3087         }
3088
3089         return handle_change_delete(o,
3090                                     path, NULL,
3091                                     o_oid, o_mode,
3092                                     changed_oid, changed_mode,
3093                                     modify_branch, delete_branch,
3094                                     _("modify"), _("modified"));
3095 }
3096
3097 static int handle_content_merge(struct merge_options *o,
3098                                 const char *path,
3099                                 int is_dirty,
3100                                 struct object_id *o_oid, int o_mode,
3101                                 struct object_id *a_oid, int a_mode,
3102                                 struct object_id *b_oid, int b_mode,
3103                                 struct rename_conflict_info *rename_conflict_info)
3104 {
3105         const char *reason = _("content");
3106         const char *path1 = NULL, *path2 = NULL;
3107         struct merge_file_info mfi;
3108         struct diff_filespec one, a, b;
3109         unsigned df_conflict_remains = 0;
3110
3111         if (!o_oid) {
3112                 reason = _("add/add");
3113                 o_oid = (struct object_id *)&null_oid;
3114         }
3115         one.path = a.path = b.path = (char *)path;
3116         oidcpy(&one.oid, o_oid);
3117         one.mode = o_mode;
3118         oidcpy(&a.oid, a_oid);
3119         a.mode = a_mode;
3120         oidcpy(&b.oid, b_oid);
3121         b.mode = b_mode;
3122
3123         if (rename_conflict_info) {
3124                 struct diff_filepair *pair1 = rename_conflict_info->pair1;
3125
3126                 path1 = (o->branch1 == rename_conflict_info->branch1) ?
3127                         pair1->two->path : pair1->one->path;
3128                 /* If rename_conflict_info->pair2 != NULL, we are in
3129                  * RENAME_ONE_FILE_TO_ONE case.  Otherwise, we have a
3130                  * normal rename.
3131                  */
3132                 path2 = (rename_conflict_info->pair2 ||
3133                          o->branch2 == rename_conflict_info->branch1) ?
3134                         pair1->two->path : pair1->one->path;
3135                 one.path = pair1->one->path;
3136                 a.path = (char *)path1;
3137                 b.path = (char *)path2;
3138
3139                 if (dir_in_way(o->repo->index, path, !o->call_depth,
3140                                S_ISGITLINK(pair1->two->mode)))
3141                         df_conflict_remains = 1;
3142         }
3143         if (merge_mode_and_contents(o, &one, &a, &b, path,
3144                                     o->branch1, o->branch2,
3145                                     o->call_depth * 2, &mfi))
3146                 return -1;
3147
3148         /*
3149          * We can skip updating the working tree file iff:
3150          *   a) The merge is clean
3151          *   b) The merge matches what was in HEAD (content, mode, pathname)
3152          *   c) The target path is usable (i.e. not involved in D/F conflict)
3153          */
3154         if (mfi.clean &&
3155             was_tracked_and_matches(o, path, &mfi.oid, mfi.mode) &&
3156             !df_conflict_remains) {
3157                 int pos;
3158                 struct cache_entry *ce;
3159
3160                 output(o, 3, _("Skipped %s (merged same as existing)"), path);
3161                 if (add_cacheinfo(o, mfi.mode, &mfi.oid, path,
3162                                   0, (!o->call_depth && !is_dirty), 0))
3163                         return -1;
3164                 /*
3165                  * However, add_cacheinfo() will delete the old cache entry
3166                  * and add a new one.  We need to copy over any skip_worktree
3167                  * flag to avoid making the file appear as if it were
3168                  * deleted by the user.
3169                  */
3170                 pos = index_name_pos(&o->orig_index, path, strlen(path));
3171                 ce = o->orig_index.cache[pos];
3172                 if (ce_skip_worktree(ce)) {
3173                         pos = index_name_pos(o->repo->index, path, strlen(path));
3174                         ce = o->repo->index->cache[pos];
3175                         ce->ce_flags |= CE_SKIP_WORKTREE;
3176                 }
3177                 return mfi.clean;
3178         }
3179
3180         if (!mfi.clean) {
3181                 if (S_ISGITLINK(mfi.mode))
3182                         reason = _("submodule");
3183                 output(o, 1, _("CONFLICT (%s): Merge conflict in %s"),
3184                                 reason, path);
3185                 if (rename_conflict_info && !df_conflict_remains)
3186                         if (update_stages(o, path, &one, &a, &b))
3187                                 return -1;
3188         }
3189
3190         if (df_conflict_remains || is_dirty) {
3191                 char *new_path;
3192                 if (o->call_depth) {
3193                         remove_file_from_index(o->repo->index, path);
3194                 } else {
3195                         if (!mfi.clean) {
3196                                 if (update_stages(o, path, &one, &a, &b))
3197                                         return -1;
3198                         } else {
3199                                 int file_from_stage2 = was_tracked(o, path);
3200                                 struct diff_filespec merged;
3201                                 oidcpy(&merged.oid, &mfi.oid);
3202                                 merged.mode = mfi.mode;
3203
3204                                 if (update_stages(o, path, NULL,
3205                                                   file_from_stage2 ? &merged : NULL,
3206                                                   file_from_stage2 ? NULL : &merged))
3207                                         return -1;
3208                         }
3209
3210                 }
3211                 new_path = unique_path(o, path, rename_conflict_info->branch1);
3212                 if (is_dirty) {
3213                         output(o, 1, _("Refusing to lose dirty file at %s"),
3214                                path);
3215                 }
3216                 output(o, 1, _("Adding as %s instead"), new_path);
3217                 if (update_file(o, 0, &mfi.oid, mfi.mode, new_path)) {
3218                         free(new_path);
3219                         return -1;
3220                 }
3221                 free(new_path);
3222                 mfi.clean = 0;
3223         } else if (update_file(o, mfi.clean, &mfi.oid, mfi.mode, path))
3224                 return -1;
3225         return !is_dirty && mfi.clean;
3226 }
3227
3228 static int handle_rename_normal(struct merge_options *o,
3229                                 const char *path,
3230                                 struct object_id *o_oid, unsigned int o_mode,
3231                                 struct object_id *a_oid, unsigned int a_mode,
3232                                 struct object_id *b_oid, unsigned int b_mode,
3233                                 struct rename_conflict_info *ci)
3234 {
3235         /* Merge the content and write it out */
3236         return handle_content_merge(o, path, was_dirty(o, path),
3237                                     o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
3238                                     ci);
3239 }
3240
3241 /* Per entry merge function */
3242 static int process_entry(struct merge_options *o,
3243                          const char *path, struct stage_data *entry)
3244 {
3245         int clean_merge = 1;
3246         int normalize = o->renormalize;
3247         unsigned o_mode = entry->stages[1].mode;
3248         unsigned a_mode = entry->stages[2].mode;
3249         unsigned b_mode = entry->stages[3].mode;
3250         struct object_id *o_oid = stage_oid(&entry->stages[1].oid, o_mode);
3251         struct object_id *a_oid = stage_oid(&entry->stages[2].oid, a_mode);
3252         struct object_id *b_oid = stage_oid(&entry->stages[3].oid, b_mode);
3253
3254         entry->processed = 1;
3255         if (entry->rename_conflict_info) {
3256                 struct rename_conflict_info *conflict_info = entry->rename_conflict_info;
3257                 switch (conflict_info->rename_type) {
3258                 case RENAME_NORMAL:
3259                 case RENAME_ONE_FILE_TO_ONE:
3260                         clean_merge = handle_rename_normal(o,
3261                                                            path,
3262                                                            o_oid, o_mode,
3263                                                            a_oid, a_mode,
3264                                                            b_oid, b_mode,
3265                                                            conflict_info);
3266                         break;
3267                 case RENAME_VIA_DIR:
3268                         clean_merge = 1;
3269                         if (handle_rename_via_dir(o,
3270                                                   conflict_info->pair1,
3271                                                   conflict_info->branch1,
3272                                                   conflict_info->branch2))
3273                                 clean_merge = -1;
3274                         break;
3275                 case RENAME_ADD:
3276                         /*
3277                          * Probably unclean merge, but if the renamed file
3278                          * merges cleanly and the result can then be
3279                          * two-way merged cleanly with the added file, I
3280                          * guess it's a clean merge?
3281                          */
3282                         clean_merge = handle_rename_add(o, conflict_info);
3283                         break;
3284                 case RENAME_DELETE:
3285                         clean_merge = 0;
3286                         if (handle_rename_delete(o,
3287                                                  conflict_info->pair1,
3288                                                  conflict_info->branch1,
3289                                                  conflict_info->branch2))
3290                                 clean_merge = -1;
3291                         break;
3292                 case RENAME_ONE_FILE_TO_TWO:
3293                         clean_merge = 0;
3294                         if (handle_rename_rename_1to2(o, conflict_info))
3295                                 clean_merge = -1;
3296                         break;
3297                 case RENAME_TWO_FILES_TO_ONE:
3298                         /*
3299                          * Probably unclean merge, but if the two renamed
3300                          * files merge cleanly and the two resulting files
3301                          * can then be two-way merged cleanly, I guess it's
3302                          * a clean merge?
3303                          */
3304                         clean_merge = handle_rename_rename_2to1(o,
3305                                                                 conflict_info);
3306                         break;
3307                 default:
3308                         entry->processed = 0;
3309                         break;
3310                 }
3311         } else if (o_oid && (!a_oid || !b_oid)) {
3312                 /* Case A: Deleted in one */
3313                 if ((!a_oid && !b_oid) ||
3314                     (!b_oid && blob_unchanged(o, o_oid, o_mode, a_oid, a_mode, normalize, path)) ||
3315                     (!a_oid && blob_unchanged(o, o_oid, o_mode, b_oid, b_mode, normalize, path))) {
3316                         /* Deleted in both or deleted in one and
3317                          * unchanged in the other */
3318                         if (a_oid)
3319                                 output(o, 2, _("Removing %s"), path);
3320                         /* do not touch working file if it did not exist */
3321                         remove_file(o, 1, path, !a_oid);
3322                 } else {
3323                         /* Modify/delete; deleted side may have put a directory in the way */
3324                         clean_merge = 0;
3325                         if (handle_modify_delete(o, path, o_oid, o_mode,
3326                                                  a_oid, a_mode, b_oid, b_mode))
3327                                 clean_merge = -1;
3328                 }
3329         } else if ((!o_oid && a_oid && !b_oid) ||
3330                    (!o_oid && !a_oid && b_oid)) {
3331                 /* Case B: Added in one. */
3332                 /* [nothing|directory] -> ([nothing|directory], file) */
3333
3334                 const char *add_branch;
3335                 const char *other_branch;
3336                 unsigned mode;
3337                 const struct object_id *oid;
3338                 const char *conf;
3339
3340                 if (a_oid) {
3341                         add_branch = o->branch1;
3342                         other_branch = o->branch2;
3343                         mode = a_mode;
3344                         oid = a_oid;
3345                         conf = _("file/directory");
3346                 } else {
3347                         add_branch = o->branch2;
3348                         other_branch = o->branch1;
3349                         mode = b_mode;
3350                         oid = b_oid;
3351                         conf = _("directory/file");
3352                 }
3353                 if (dir_in_way(o->repo->index, path,
3354                                !o->call_depth && !S_ISGITLINK(a_mode),
3355                                0)) {
3356                         char *new_path = unique_path(o, path, add_branch);
3357                         clean_merge = 0;
3358                         output(o, 1, _("CONFLICT (%s): There is a directory with name %s in %s. "
3359                                "Adding %s as %s"),
3360                                conf, path, other_branch, path, new_path);
3361                         if (update_file(o, 0, oid, mode, new_path))
3362                                 clean_merge = -1;
3363                         else if (o->call_depth)
3364                                 remove_file_from_index(o->repo->index, path);
3365                         free(new_path);
3366                 } else {
3367                         output(o, 2, _("Adding %s"), path);
3368                         /* do not overwrite file if already present */
3369                         if (update_file_flags(o, oid, mode, path, 1, !a_oid))
3370                                 clean_merge = -1;
3371                 }
3372         } else if (a_oid && b_oid) {
3373                 if (!o_oid) {
3374                         /* Case C: Added in both (check for same permissions) */
3375                         output(o, 1,
3376                                _("CONFLICT (add/add): Merge conflict in %s"),
3377                                path);
3378                         clean_merge = handle_file_collision(o,
3379                                                             path, NULL, NULL,
3380                                                             o->branch1,
3381                                                             o->branch2,
3382                                                             a_oid, a_mode,
3383                                                             b_oid, b_mode);
3384                 } else {
3385                         /* case D: Modified in both, but differently. */
3386                         int is_dirty = 0; /* unpack_trees would have bailed if dirty */
3387                         clean_merge = handle_content_merge(o, path,
3388                                                            is_dirty,
3389                                                            o_oid, o_mode,
3390                                                            a_oid, a_mode,
3391                                                            b_oid, b_mode,
3392                                                            NULL);
3393                 }
3394         } else if (!o_oid && !a_oid && !b_oid) {
3395                 /*
3396                  * this entry was deleted altogether. a_mode == 0 means
3397                  * we had that path and want to actively remove it.
3398                  */
3399                 remove_file(o, 1, path, !a_mode);
3400         } else
3401                 BUG("fatal merge failure, shouldn't happen.");
3402
3403         return clean_merge;
3404 }
3405
3406 int merge_trees(struct merge_options *o,
3407                 struct tree *head,
3408                 struct tree *merge,
3409                 struct tree *common,
3410                 struct tree **result)
3411 {
3412         struct index_state *istate = o->repo->index;
3413         int code, clean;
3414         struct strbuf sb = STRBUF_INIT;
3415
3416         if (!o->call_depth && repo_index_has_changes(o->repo, head, &sb)) {
3417                 err(o, _("Your local changes to the following files would be overwritten by merge:\n  %s"),
3418                     sb.buf);
3419                 return -1;
3420         }
3421
3422         if (o->subtree_shift) {
3423                 merge = shift_tree_object(o->repo, head, merge, o->subtree_shift);
3424                 common = shift_tree_object(o->repo, head, common, o->subtree_shift);
3425         }
3426
3427         if (oid_eq(&common->object.oid, &merge->object.oid)) {
3428                 output(o, 0, _("Already up to date!"));
3429                 *result = head;
3430                 return 1;
3431         }
3432
3433         code = unpack_trees_start(o, common, head, merge);
3434
3435         if (code != 0) {
3436                 if (show(o, 4) || o->call_depth)
3437                         err(o, _("merging of trees %s and %s failed"),
3438                             oid_to_hex(&head->object.oid),
3439                             oid_to_hex(&merge->object.oid));
3440                 unpack_trees_finish(o);
3441                 return -1;
3442         }
3443
3444         if (unmerged_index(istate)) {
3445                 struct string_list *entries;
3446                 struct rename_info re_info;
3447                 int i;
3448                 /*
3449                  * Only need the hashmap while processing entries, so
3450                  * initialize it here and free it when we are done running
3451                  * through the entries. Keeping it in the merge_options as
3452                  * opposed to decaring a local hashmap is for convenience
3453                  * so that we don't have to pass it to around.
3454                  */
3455                 hashmap_init(&o->current_file_dir_set, path_hashmap_cmp, NULL, 512);
3456                 get_files_dirs(o, head);
3457                 get_files_dirs(o, merge);
3458
3459                 entries = get_unmerged(o->repo->index);
3460                 clean = detect_and_process_renames(o, common, head, merge,
3461                                                    entries, &re_info);
3462                 record_df_conflict_files(o, entries);
3463                 if (clean < 0)
3464                         goto cleanup;
3465                 for (i = entries->nr-1; 0 <= i; i--) {
3466                         const char *path = entries->items[i].string;
3467                         struct stage_data *e = entries->items[i].util;
3468                         if (!e->processed) {
3469                                 int ret = process_entry(o, path, e);
3470                                 if (!ret)
3471                                         clean = 0;
3472                                 else if (ret < 0) {
3473                                         clean = ret;
3474                                         goto cleanup;
3475                                 }
3476                         }
3477                 }
3478                 for (i = 0; i < entries->nr; i++) {
3479                         struct stage_data *e = entries->items[i].util;
3480                         if (!e->processed)
3481                                 BUG("unprocessed path??? %s",
3482                                     entries->items[i].string);
3483                 }
3484
3485         cleanup:
3486                 final_cleanup_renames(&re_info);
3487
3488                 string_list_clear(entries, 1);
3489                 free(entries);
3490
3491                 hashmap_free(&o->current_file_dir_set, 1);
3492
3493                 if (clean < 0) {
3494                         unpack_trees_finish(o);
3495                         return clean;
3496                 }
3497         }
3498         else
3499                 clean = 1;
3500
3501         unpack_trees_finish(o);
3502
3503         if (o->call_depth && !(*result = write_tree_from_memory(o)))
3504                 return -1;
3505
3506         return clean;
3507 }
3508
3509 static struct commit_list *reverse_commit_list(struct commit_list *list)
3510 {
3511         struct commit_list *next = NULL, *current, *backup;
3512         for (current = list; current; current = backup) {
3513                 backup = current->next;
3514                 current->next = next;
3515                 next = current;
3516         }
3517         return next;
3518 }
3519
3520 /*
3521  * Merge the commits h1 and h2, return the resulting virtual
3522  * commit object and a flag indicating the cleanness of the merge.
3523  */
3524 int merge_recursive(struct merge_options *o,
3525                     struct commit *h1,
3526                     struct commit *h2,
3527                     struct commit_list *ca,
3528                     struct commit **result)
3529 {
3530         struct commit_list *iter;
3531         struct commit *merged_common_ancestors;
3532         struct tree *mrtree;
3533         int clean;
3534
3535         if (show(o, 4)) {
3536                 output(o, 4, _("Merging:"));
3537                 output_commit_title(o, h1);
3538                 output_commit_title(o, h2);
3539         }
3540
3541         if (!ca) {
3542                 ca = get_merge_bases(h1, h2);
3543                 ca = reverse_commit_list(ca);
3544         }
3545
3546         if (show(o, 5)) {
3547                 unsigned cnt = commit_list_count(ca);
3548
3549                 output(o, 5, Q_("found %u common ancestor:",
3550                                 "found %u common ancestors:", cnt), cnt);
3551                 for (iter = ca; iter; iter = iter->next)
3552                         output_commit_title(o, iter->item);
3553         }
3554
3555         merged_common_ancestors = pop_commit(&ca);
3556         if (merged_common_ancestors == NULL) {
3557                 /* if there is no common ancestor, use an empty tree */
3558                 struct tree *tree;
3559
3560                 tree = lookup_tree(o->repo, o->repo->hash_algo->empty_tree);
3561                 merged_common_ancestors = make_virtual_commit(o->repo, tree, "ancestor");
3562         }
3563
3564         for (iter = ca; iter; iter = iter->next) {
3565                 const char *saved_b1, *saved_b2;
3566                 o->call_depth++;
3567                 /*
3568                  * When the merge fails, the result contains files
3569                  * with conflict markers. The cleanness flag is
3570                  * ignored (unless indicating an error), it was never
3571                  * actually used, as result of merge_trees has always
3572                  * overwritten it: the committed "conflicts" were
3573                  * already resolved.
3574                  */
3575                 discard_index(o->repo->index);
3576                 saved_b1 = o->branch1;
3577                 saved_b2 = o->branch2;
3578                 o->branch1 = "Temporary merge branch 1";
3579                 o->branch2 = "Temporary merge branch 2";
3580                 if (merge_recursive(o, merged_common_ancestors, iter->item,
3581                                     NULL, &merged_common_ancestors) < 0)
3582                         return -1;
3583                 o->branch1 = saved_b1;
3584                 o->branch2 = saved_b2;
3585                 o->call_depth--;
3586
3587                 if (!merged_common_ancestors)
3588                         return err(o, _("merge returned no commit"));
3589         }
3590
3591         discard_index(o->repo->index);
3592         if (!o->call_depth)
3593                 repo_read_index(o->repo);
3594
3595         o->ancestor = "merged common ancestors";
3596         clean = merge_trees(o, get_commit_tree(h1), get_commit_tree(h2),
3597                             get_commit_tree(merged_common_ancestors),
3598                             &mrtree);
3599         if (clean < 0) {
3600                 flush_output(o);
3601                 return clean;
3602         }
3603
3604         if (o->call_depth) {
3605                 *result = make_virtual_commit(o->repo, mrtree, "merged tree");
3606                 commit_list_insert(h1, &(*result)->parents);
3607                 commit_list_insert(h2, &(*result)->parents->next);
3608         }
3609         flush_output(o);
3610         if (!o->call_depth && o->buffer_output < 2)
3611                 strbuf_release(&o->obuf);
3612         if (show(o, 2))
3613                 diff_warn_rename_limit("merge.renamelimit",
3614                                        o->needed_rename_limit, 0);
3615         return clean;
3616 }
3617
3618 static struct commit *get_ref(struct repository *repo, const struct object_id *oid,
3619                               const char *name)
3620 {
3621         struct object *object;
3622
3623         object = deref_tag(repo, parse_object(repo, oid),
3624                            name, strlen(name));
3625         if (!object)
3626                 return NULL;
3627         if (object->type == OBJ_TREE)
3628                 return make_virtual_commit(repo, (struct tree*)object, name);
3629         if (object->type != OBJ_COMMIT)
3630                 return NULL;
3631         if (parse_commit((struct commit *)object))
3632                 return NULL;
3633         return (struct commit *)object;
3634 }
3635
3636 int merge_recursive_generic(struct merge_options *o,
3637                             const struct object_id *head,
3638                             const struct object_id *merge,
3639                             int num_base_list,
3640                             const struct object_id **base_list,
3641                             struct commit **result)
3642 {
3643         int clean;
3644         struct lock_file lock = LOCK_INIT;
3645         struct commit *head_commit = get_ref(o->repo, head, o->branch1);
3646         struct commit *next_commit = get_ref(o->repo, merge, o->branch2);
3647         struct commit_list *ca = NULL;
3648
3649         if (base_list) {
3650                 int i;
3651                 for (i = 0; i < num_base_list; ++i) {
3652                         struct commit *base;
3653                         if (!(base = get_ref(o->repo, base_list[i], oid_to_hex(base_list[i]))))
3654                                 return err(o, _("Could not parse object '%s'"),
3655                                            oid_to_hex(base_list[i]));
3656                         commit_list_insert(base, &ca);
3657                 }
3658         }
3659
3660         repo_hold_locked_index(o->repo, &lock, LOCK_DIE_ON_ERROR);
3661         clean = merge_recursive(o, head_commit, next_commit, ca,
3662                                 result);
3663         if (clean < 0) {
3664                 rollback_lock_file(&lock);
3665                 return clean;
3666         }
3667
3668         if (write_locked_index(o->repo->index, &lock,
3669                                COMMIT_LOCK | SKIP_IF_UNCHANGED))
3670                 return err(o, _("Unable to write index."));
3671
3672         return clean ? 0 : 1;
3673 }
3674
3675 static void merge_recursive_config(struct merge_options *o)
3676 {
3677         char *value = NULL;
3678         git_config_get_int("merge.verbosity", &o->verbosity);
3679         git_config_get_int("diff.renamelimit", &o->diff_rename_limit);
3680         git_config_get_int("merge.renamelimit", &o->merge_rename_limit);
3681         if (!git_config_get_string("diff.renames", &value)) {
3682                 o->diff_detect_rename = git_config_rename("diff.renames", value);
3683                 free(value);
3684         }
3685         if (!git_config_get_string("merge.renames", &value)) {
3686                 o->merge_detect_rename = git_config_rename("merge.renames", value);
3687                 free(value);
3688         }
3689         git_config(git_xmerge_config, NULL);
3690 }
3691
3692 void init_merge_options(struct merge_options *o,
3693                         struct repository *repo)
3694 {
3695         const char *merge_verbosity;
3696         memset(o, 0, sizeof(struct merge_options));
3697         o->repo = repo;
3698         o->verbosity = 2;
3699         o->buffer_output = 1;
3700         o->diff_rename_limit = -1;
3701         o->merge_rename_limit = -1;
3702         o->renormalize = 0;
3703         o->diff_detect_rename = -1;
3704         o->merge_detect_rename = -1;
3705         o->detect_directory_renames = 1;
3706         merge_recursive_config(o);
3707         merge_verbosity = getenv("GIT_MERGE_VERBOSITY");
3708         if (merge_verbosity)
3709                 o->verbosity = strtol(merge_verbosity, NULL, 10);
3710         if (o->verbosity >= 5)
3711                 o->buffer_output = 0;
3712         strbuf_init(&o->obuf, 0);
3713         string_list_init(&o->df_conflict_file_set, 1);
3714 }
3715
3716 int parse_merge_opt(struct merge_options *o, const char *s)
3717 {
3718         const char *arg;
3719
3720         if (!s || !*s)
3721                 return -1;
3722         if (!strcmp(s, "ours"))
3723                 o->recursive_variant = MERGE_RECURSIVE_OURS;
3724         else if (!strcmp(s, "theirs"))
3725                 o->recursive_variant = MERGE_RECURSIVE_THEIRS;
3726         else if (!strcmp(s, "subtree"))
3727                 o->subtree_shift = "";
3728         else if (skip_prefix(s, "subtree=", &arg))
3729                 o->subtree_shift = arg;
3730         else if (!strcmp(s, "patience"))
3731                 o->xdl_opts = DIFF_WITH_ALG(o, PATIENCE_DIFF);
3732         else if (!strcmp(s, "histogram"))
3733                 o->xdl_opts = DIFF_WITH_ALG(o, HISTOGRAM_DIFF);
3734         else if (skip_prefix(s, "diff-algorithm=", &arg)) {
3735                 long value = parse_algorithm_value(arg);
3736                 if (value < 0)
3737                         return -1;
3738                 /* clear out previous settings */
3739                 DIFF_XDL_CLR(o, NEED_MINIMAL);
3740                 o->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
3741                 o->xdl_opts |= value;
3742         }
3743         else if (!strcmp(s, "ignore-space-change"))
3744                 DIFF_XDL_SET(o, IGNORE_WHITESPACE_CHANGE);
3745         else if (!strcmp(s, "ignore-all-space"))
3746                 DIFF_XDL_SET(o, IGNORE_WHITESPACE);
3747         else if (!strcmp(s, "ignore-space-at-eol"))
3748                 DIFF_XDL_SET(o, IGNORE_WHITESPACE_AT_EOL);
3749         else if (!strcmp(s, "ignore-cr-at-eol"))
3750                 DIFF_XDL_SET(o, IGNORE_CR_AT_EOL);
3751         else if (!strcmp(s, "renormalize"))
3752                 o->renormalize = 1;
3753         else if (!strcmp(s, "no-renormalize"))
3754                 o->renormalize = 0;
3755         else if (!strcmp(s, "no-renames"))
3756                 o->merge_detect_rename = 0;
3757         else if (!strcmp(s, "find-renames")) {
3758                 o->merge_detect_rename = 1;
3759                 o->rename_score = 0;
3760         }
3761         else if (skip_prefix(s, "find-renames=", &arg) ||
3762                  skip_prefix(s, "rename-threshold=", &arg)) {
3763                 if ((o->rename_score = parse_rename_score(&arg)) == -1 || *arg != 0)
3764                         return -1;
3765                 o->merge_detect_rename = 1;
3766         }
3767         else
3768                 return -1;
3769         return 0;
3770 }