Merge branch 'en/rename-directory-detection-reboot'
[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 "commit.h"
12 #include "blob.h"
13 #include "builtin.h"
14 #include "tree-walk.h"
15 #include "diff.h"
16 #include "diffcore.h"
17 #include "tag.h"
18 #include "unpack-trees.h"
19 #include "string-list.h"
20 #include "xdiff-interface.h"
21 #include "ll-merge.h"
22 #include "attr.h"
23 #include "merge-recursive.h"
24 #include "dir.h"
25 #include "submodule.h"
26
27 struct path_hashmap_entry {
28         struct hashmap_entry e;
29         char path[FLEX_ARRAY];
30 };
31
32 static int path_hashmap_cmp(const void *cmp_data,
33                             const void *entry,
34                             const void *entry_or_key,
35                             const void *keydata)
36 {
37         const struct path_hashmap_entry *a = entry;
38         const struct path_hashmap_entry *b = entry_or_key;
39         const char *key = keydata;
40
41         if (ignore_case)
42                 return strcasecmp(a->path, key ? key : b->path);
43         else
44                 return strcmp(a->path, key ? key : b->path);
45 }
46
47 static unsigned int path_hash(const char *path)
48 {
49         return ignore_case ? strihash(path) : strhash(path);
50 }
51
52 static struct dir_rename_entry *dir_rename_find_entry(struct hashmap *hashmap,
53                                                       char *dir)
54 {
55         struct dir_rename_entry key;
56
57         if (dir == NULL)
58                 return NULL;
59         hashmap_entry_init(&key, strhash(dir));
60         key.dir = dir;
61         return hashmap_get(hashmap, &key, NULL);
62 }
63
64 static int dir_rename_cmp(const void *unused_cmp_data,
65                           const void *entry,
66                           const void *entry_or_key,
67                           const void *unused_keydata)
68 {
69         const struct dir_rename_entry *e1 = entry;
70         const struct dir_rename_entry *e2 = entry_or_key;
71
72         return strcmp(e1->dir, e2->dir);
73 }
74
75 static void dir_rename_init(struct hashmap *map)
76 {
77         hashmap_init(map, dir_rename_cmp, NULL, 0);
78 }
79
80 static void dir_rename_entry_init(struct dir_rename_entry *entry,
81                                   char *directory)
82 {
83         hashmap_entry_init(entry, strhash(directory));
84         entry->dir = directory;
85         entry->non_unique_new_dir = 0;
86         strbuf_init(&entry->new_dir, 0);
87         string_list_init(&entry->possible_new_dirs, 0);
88 }
89
90 static struct collision_entry *collision_find_entry(struct hashmap *hashmap,
91                                                     char *target_file)
92 {
93         struct collision_entry key;
94
95         hashmap_entry_init(&key, strhash(target_file));
96         key.target_file = target_file;
97         return hashmap_get(hashmap, &key, NULL);
98 }
99
100 static int collision_cmp(void *unused_cmp_data,
101                          const struct collision_entry *e1,
102                          const struct collision_entry *e2,
103                          const void *unused_keydata)
104 {
105         return strcmp(e1->target_file, e2->target_file);
106 }
107
108 static void collision_init(struct hashmap *map)
109 {
110         hashmap_init(map, (hashmap_cmp_fn) collision_cmp, NULL, 0);
111 }
112
113 static void flush_output(struct merge_options *o)
114 {
115         if (o->buffer_output < 2 && o->obuf.len) {
116                 fputs(o->obuf.buf, stdout);
117                 strbuf_reset(&o->obuf);
118         }
119 }
120
121 static int err(struct merge_options *o, const char *err, ...)
122 {
123         va_list params;
124
125         if (o->buffer_output < 2)
126                 flush_output(o);
127         else {
128                 strbuf_complete(&o->obuf, '\n');
129                 strbuf_addstr(&o->obuf, "error: ");
130         }
131         va_start(params, err);
132         strbuf_vaddf(&o->obuf, err, params);
133         va_end(params);
134         if (o->buffer_output > 1)
135                 strbuf_addch(&o->obuf, '\n');
136         else {
137                 error("%s", o->obuf.buf);
138                 strbuf_reset(&o->obuf);
139         }
140
141         return -1;
142 }
143
144 static struct tree *shift_tree_object(struct tree *one, struct tree *two,
145                                       const char *subtree_shift)
146 {
147         struct object_id shifted;
148
149         if (!*subtree_shift) {
150                 shift_tree(&one->object.oid, &two->object.oid, &shifted, 0);
151         } else {
152                 shift_tree_by(&one->object.oid, &two->object.oid, &shifted,
153                               subtree_shift);
154         }
155         if (!oidcmp(&two->object.oid, &shifted))
156                 return two;
157         return lookup_tree(&shifted);
158 }
159
160 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
161 {
162         struct commit *commit = alloc_commit_node();
163
164         set_merge_remote_desc(commit, comment, (struct object *)commit);
165         commit->maybe_tree = tree;
166         commit->object.parsed = 1;
167         return commit;
168 }
169
170 /*
171  * Since we use get_tree_entry(), which does not put the read object into
172  * the object pool, we cannot rely on a == b.
173  */
174 static int oid_eq(const struct object_id *a, const struct object_id *b)
175 {
176         if (!a && !b)
177                 return 2;
178         return a && b && oidcmp(a, b) == 0;
179 }
180
181 enum rename_type {
182         RENAME_NORMAL = 0,
183         RENAME_DIR,
184         RENAME_DELETE,
185         RENAME_ONE_FILE_TO_ONE,
186         RENAME_ONE_FILE_TO_TWO,
187         RENAME_TWO_FILES_TO_ONE
188 };
189
190 struct rename_conflict_info {
191         enum rename_type rename_type;
192         struct diff_filepair *pair1;
193         struct diff_filepair *pair2;
194         const char *branch1;
195         const char *branch2;
196         struct stage_data *dst_entry1;
197         struct stage_data *dst_entry2;
198         struct diff_filespec ren1_other;
199         struct diff_filespec ren2_other;
200 };
201
202 /*
203  * Since we want to write the index eventually, we cannot reuse the index
204  * for these (temporary) data.
205  */
206 struct stage_data {
207         struct {
208                 unsigned mode;
209                 struct object_id oid;
210         } stages[4];
211         struct rename_conflict_info *rename_conflict_info;
212         unsigned processed:1;
213 };
214
215 static inline void setup_rename_conflict_info(enum rename_type rename_type,
216                                               struct diff_filepair *pair1,
217                                               struct diff_filepair *pair2,
218                                               const char *branch1,
219                                               const char *branch2,
220                                               struct stage_data *dst_entry1,
221                                               struct stage_data *dst_entry2,
222                                               struct merge_options *o,
223                                               struct stage_data *src_entry1,
224                                               struct stage_data *src_entry2)
225 {
226         struct rename_conflict_info *ci = xcalloc(1, sizeof(struct rename_conflict_info));
227         ci->rename_type = rename_type;
228         ci->pair1 = pair1;
229         ci->branch1 = branch1;
230         ci->branch2 = branch2;
231
232         ci->dst_entry1 = dst_entry1;
233         dst_entry1->rename_conflict_info = ci;
234         dst_entry1->processed = 0;
235
236         assert(!pair2 == !dst_entry2);
237         if (dst_entry2) {
238                 ci->dst_entry2 = dst_entry2;
239                 ci->pair2 = pair2;
240                 dst_entry2->rename_conflict_info = ci;
241         }
242
243         if (rename_type == RENAME_TWO_FILES_TO_ONE) {
244                 /*
245                  * For each rename, there could have been
246                  * modifications on the side of history where that
247                  * file was not renamed.
248                  */
249                 int ostage1 = o->branch1 == branch1 ? 3 : 2;
250                 int ostage2 = ostage1 ^ 1;
251
252                 ci->ren1_other.path = pair1->one->path;
253                 oidcpy(&ci->ren1_other.oid, &src_entry1->stages[ostage1].oid);
254                 ci->ren1_other.mode = src_entry1->stages[ostage1].mode;
255
256                 ci->ren2_other.path = pair2->one->path;
257                 oidcpy(&ci->ren2_other.oid, &src_entry2->stages[ostage2].oid);
258                 ci->ren2_other.mode = src_entry2->stages[ostage2].mode;
259         }
260 }
261
262 static int show(struct merge_options *o, int v)
263 {
264         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
265 }
266
267 __attribute__((format (printf, 3, 4)))
268 static void output(struct merge_options *o, int v, const char *fmt, ...)
269 {
270         va_list ap;
271
272         if (!show(o, v))
273                 return;
274
275         strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
276
277         va_start(ap, fmt);
278         strbuf_vaddf(&o->obuf, fmt, ap);
279         va_end(ap);
280
281         strbuf_addch(&o->obuf, '\n');
282         if (!o->buffer_output)
283                 flush_output(o);
284 }
285
286 static void output_commit_title(struct merge_options *o, struct commit *commit)
287 {
288         strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
289         if (commit->util)
290                 strbuf_addf(&o->obuf, "virtual %s\n",
291                         merge_remote_util(commit)->name);
292         else {
293                 strbuf_add_unique_abbrev(&o->obuf, &commit->object.oid,
294                                          DEFAULT_ABBREV);
295                 strbuf_addch(&o->obuf, ' ');
296                 if (parse_commit(commit) != 0)
297                         strbuf_addstr(&o->obuf, _("(bad commit)\n"));
298                 else {
299                         const char *title;
300                         const char *msg = get_commit_buffer(commit, NULL);
301                         int len = find_commit_subject(msg, &title);
302                         if (len)
303                                 strbuf_addf(&o->obuf, "%.*s\n", len, title);
304                         unuse_commit_buffer(commit, msg);
305                 }
306         }
307         flush_output(o);
308 }
309
310 static int add_cacheinfo(struct merge_options *o,
311                 unsigned int mode, const struct object_id *oid,
312                 const char *path, int stage, int refresh, int options)
313 {
314         struct cache_entry *ce;
315         int ret;
316
317         ce = make_cache_entry(mode, oid ? oid->hash : null_sha1, path, stage, 0);
318         if (!ce)
319                 return err(o, _("add_cacheinfo failed for path '%s'; merge aborting."), path);
320
321         ret = add_cache_entry(ce, options);
322         if (refresh) {
323                 struct cache_entry *nce;
324
325                 nce = refresh_cache_entry(ce, CE_MATCH_REFRESH | CE_MATCH_IGNORE_MISSING);
326                 if (!nce)
327                         return err(o, _("add_cacheinfo failed to refresh for path '%s'; merge aborting."), path);
328                 if (nce != ce)
329                         ret = add_cache_entry(nce, options);
330         }
331         return ret;
332 }
333
334 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
335 {
336         parse_tree(tree);
337         init_tree_desc(desc, tree->buffer, tree->size);
338 }
339
340 static int git_merge_trees(struct merge_options *o,
341                            struct tree *common,
342                            struct tree *head,
343                            struct tree *merge)
344 {
345         int rc;
346         struct tree_desc t[3];
347         struct index_state tmp_index = { NULL };
348
349         memset(&o->unpack_opts, 0, sizeof(o->unpack_opts));
350         if (o->call_depth)
351                 o->unpack_opts.index_only = 1;
352         else
353                 o->unpack_opts.update = 1;
354         o->unpack_opts.merge = 1;
355         o->unpack_opts.head_idx = 2;
356         o->unpack_opts.fn = threeway_merge;
357         o->unpack_opts.src_index = &the_index;
358         o->unpack_opts.dst_index = &tmp_index;
359         setup_unpack_trees_porcelain(&o->unpack_opts, "merge");
360
361         init_tree_desc_from_tree(t+0, common);
362         init_tree_desc_from_tree(t+1, head);
363         init_tree_desc_from_tree(t+2, merge);
364
365         rc = unpack_trees(3, t, &o->unpack_opts);
366         cache_tree_free(&active_cache_tree);
367
368         /*
369          * Update the_index to match the new results, AFTER saving a copy
370          * in o->orig_index.  Update src_index to point to the saved copy.
371          * (verify_uptodate() checks src_index, and the original index is
372          * the one that had the necessary modification timestamps.)
373          */
374         o->orig_index = the_index;
375         the_index = tmp_index;
376         o->unpack_opts.src_index = &o->orig_index;
377
378         return rc;
379 }
380
381 struct tree *write_tree_from_memory(struct merge_options *o)
382 {
383         struct tree *result = NULL;
384
385         if (unmerged_cache()) {
386                 int i;
387                 fprintf(stderr, "BUG: There are unmerged index entries:\n");
388                 for (i = 0; i < active_nr; i++) {
389                         const struct cache_entry *ce = active_cache[i];
390                         if (ce_stage(ce))
391                                 fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
392                                         (int)ce_namelen(ce), ce->name);
393                 }
394                 die("BUG: unmerged index entries in merge-recursive.c");
395         }
396
397         if (!active_cache_tree)
398                 active_cache_tree = cache_tree();
399
400         if (!cache_tree_fully_valid(active_cache_tree) &&
401             cache_tree_update(&the_index, 0) < 0) {
402                 err(o, _("error building trees"));
403                 return NULL;
404         }
405
406         result = lookup_tree(&active_cache_tree->oid);
407
408         return result;
409 }
410
411 static int save_files_dirs(const struct object_id *oid,
412                 struct strbuf *base, const char *path,
413                 unsigned int mode, int stage, void *context)
414 {
415         struct path_hashmap_entry *entry;
416         int baselen = base->len;
417         struct merge_options *o = context;
418
419         strbuf_addstr(base, path);
420
421         FLEX_ALLOC_MEM(entry, path, base->buf, base->len);
422         hashmap_entry_init(entry, path_hash(entry->path));
423         hashmap_add(&o->current_file_dir_set, entry);
424
425         strbuf_setlen(base, baselen);
426         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
427 }
428
429 static void get_files_dirs(struct merge_options *o, struct tree *tree)
430 {
431         struct pathspec match_all;
432         memset(&match_all, 0, sizeof(match_all));
433         read_tree_recursive(tree, "", 0, 0, &match_all, save_files_dirs, o);
434 }
435
436 static int get_tree_entry_if_blob(const struct object_id *tree,
437                                   const char *path,
438                                   struct object_id *hashy,
439                                   unsigned int *mode_o)
440 {
441         int ret;
442
443         ret = get_tree_entry(tree, path, hashy, mode_o);
444         if (S_ISDIR(*mode_o)) {
445                 oidcpy(hashy, &null_oid);
446                 *mode_o = 0;
447         }
448         return ret;
449 }
450
451 /*
452  * Returns an index_entry instance which doesn't have to correspond to
453  * a real cache entry in Git's index.
454  */
455 static struct stage_data *insert_stage_data(const char *path,
456                 struct tree *o, struct tree *a, struct tree *b,
457                 struct string_list *entries)
458 {
459         struct string_list_item *item;
460         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
461         get_tree_entry_if_blob(&o->object.oid, path,
462                                &e->stages[1].oid, &e->stages[1].mode);
463         get_tree_entry_if_blob(&a->object.oid, path,
464                                &e->stages[2].oid, &e->stages[2].mode);
465         get_tree_entry_if_blob(&b->object.oid, path,
466                                &e->stages[3].oid, &e->stages[3].mode);
467         item = string_list_insert(entries, path);
468         item->util = e;
469         return e;
470 }
471
472 /*
473  * Create a dictionary mapping file names to stage_data objects. The
474  * dictionary contains one entry for every path with a non-zero stage entry.
475  */
476 static struct string_list *get_unmerged(void)
477 {
478         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
479         int i;
480
481         unmerged->strdup_strings = 1;
482
483         for (i = 0; i < active_nr; i++) {
484                 struct string_list_item *item;
485                 struct stage_data *e;
486                 const struct cache_entry *ce = active_cache[i];
487                 if (!ce_stage(ce))
488                         continue;
489
490                 item = string_list_lookup(unmerged, ce->name);
491                 if (!item) {
492                         item = string_list_insert(unmerged, ce->name);
493                         item->util = xcalloc(1, sizeof(struct stage_data));
494                 }
495                 e = item->util;
496                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
497                 oidcpy(&e->stages[ce_stage(ce)].oid, &ce->oid);
498         }
499
500         return unmerged;
501 }
502
503 static int string_list_df_name_compare(const char *one, const char *two)
504 {
505         int onelen = strlen(one);
506         int twolen = strlen(two);
507         /*
508          * Here we only care that entries for D/F conflicts are
509          * adjacent, in particular with the file of the D/F conflict
510          * appearing before files below the corresponding directory.
511          * The order of the rest of the list is irrelevant for us.
512          *
513          * To achieve this, we sort with df_name_compare and provide
514          * the mode S_IFDIR so that D/F conflicts will sort correctly.
515          * We use the mode S_IFDIR for everything else for simplicity,
516          * since in other cases any changes in their order due to
517          * sorting cause no problems for us.
518          */
519         int cmp = df_name_compare(one, onelen, S_IFDIR,
520                                   two, twolen, S_IFDIR);
521         /*
522          * Now that 'foo' and 'foo/bar' compare equal, we have to make sure
523          * that 'foo' comes before 'foo/bar'.
524          */
525         if (cmp)
526                 return cmp;
527         return onelen - twolen;
528 }
529
530 static void record_df_conflict_files(struct merge_options *o,
531                                      struct string_list *entries)
532 {
533         /* If there is a D/F conflict and the file for such a conflict
534          * currently exist in the working tree, we want to allow it to be
535          * removed to make room for the corresponding directory if needed.
536          * The files underneath the directories of such D/F conflicts will
537          * be processed before the corresponding file involved in the D/F
538          * conflict.  If the D/F directory ends up being removed by the
539          * merge, then we won't have to touch the D/F file.  If the D/F
540          * directory needs to be written to the working copy, then the D/F
541          * file will simply be removed (in make_room_for_path()) to make
542          * room for the necessary paths.  Note that if both the directory
543          * and the file need to be present, then the D/F file will be
544          * reinstated with a new unique name at the time it is processed.
545          */
546         struct string_list df_sorted_entries = STRING_LIST_INIT_NODUP;
547         const char *last_file = NULL;
548         int last_len = 0;
549         int i;
550
551         /*
552          * If we're merging merge-bases, we don't want to bother with
553          * any working directory changes.
554          */
555         if (o->call_depth)
556                 return;
557
558         /* Ensure D/F conflicts are adjacent in the entries list. */
559         for (i = 0; i < entries->nr; i++) {
560                 struct string_list_item *next = &entries->items[i];
561                 string_list_append(&df_sorted_entries, next->string)->util =
562                                    next->util;
563         }
564         df_sorted_entries.cmp = string_list_df_name_compare;
565         string_list_sort(&df_sorted_entries);
566
567         string_list_clear(&o->df_conflict_file_set, 1);
568         for (i = 0; i < df_sorted_entries.nr; i++) {
569                 const char *path = df_sorted_entries.items[i].string;
570                 int len = strlen(path);
571                 struct stage_data *e = df_sorted_entries.items[i].util;
572
573                 /*
574                  * Check if last_file & path correspond to a D/F conflict;
575                  * i.e. whether path is last_file+'/'+<something>.
576                  * If so, record that it's okay to remove last_file to make
577                  * room for path and friends if needed.
578                  */
579                 if (last_file &&
580                     len > last_len &&
581                     memcmp(path, last_file, last_len) == 0 &&
582                     path[last_len] == '/') {
583                         string_list_insert(&o->df_conflict_file_set, last_file);
584                 }
585
586                 /*
587                  * Determine whether path could exist as a file in the
588                  * working directory as a possible D/F conflict.  This
589                  * will only occur when it exists in stage 2 as a
590                  * file.
591                  */
592                 if (S_ISREG(e->stages[2].mode) || S_ISLNK(e->stages[2].mode)) {
593                         last_file = path;
594                         last_len = len;
595                 } else {
596                         last_file = NULL;
597                 }
598         }
599         string_list_clear(&df_sorted_entries, 0);
600 }
601
602 struct rename {
603         struct diff_filepair *pair;
604         /*
605          * Purpose of src_entry and dst_entry:
606          *
607          * If 'before' is renamed to 'after' then src_entry will contain
608          * the versions of 'before' from the merge_base, HEAD, and MERGE in
609          * stages 1, 2, and 3; dst_entry will contain the respective
610          * versions of 'after' in corresponding locations.  Thus, we have a
611          * total of six modes and oids, though some will be null.  (Stage 0
612          * is ignored; we're interested in handling conflicts.)
613          *
614          * Since we don't turn on break-rewrites by default, neither
615          * src_entry nor dst_entry can have all three of their stages have
616          * non-null oids, meaning at most four of the six will be non-null.
617          * Also, since this is a rename, both src_entry and dst_entry will
618          * have at least one non-null oid, meaning at least two will be
619          * non-null.  Of the six oids, a typical rename will have three be
620          * non-null.  Only two implies a rename/delete, and four implies a
621          * rename/add.
622          */
623         struct stage_data *src_entry;
624         struct stage_data *dst_entry;
625         unsigned add_turned_into_rename:1;
626         unsigned processed:1;
627 };
628
629 static int update_stages(struct merge_options *opt, const char *path,
630                          const struct diff_filespec *o,
631                          const struct diff_filespec *a,
632                          const struct diff_filespec *b)
633 {
634
635         /*
636          * NOTE: It is usually a bad idea to call update_stages on a path
637          * before calling update_file on that same path, since it can
638          * sometimes lead to spurious "refusing to lose untracked file..."
639          * messages from update_file (via make_room_for path via
640          * would_lose_untracked).  Instead, reverse the order of the calls
641          * (executing update_file first and then update_stages).
642          */
643         int clear = 1;
644         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_SKIP_DFCHECK;
645         if (clear)
646                 if (remove_file_from_cache(path))
647                         return -1;
648         if (o)
649                 if (add_cacheinfo(opt, o->mode, &o->oid, path, 1, 0, options))
650                         return -1;
651         if (a)
652                 if (add_cacheinfo(opt, a->mode, &a->oid, path, 2, 0, options))
653                         return -1;
654         if (b)
655                 if (add_cacheinfo(opt, b->mode, &b->oid, path, 3, 0, options))
656                         return -1;
657         return 0;
658 }
659
660 static int update_stages_for_stage_data(struct merge_options *opt,
661                                         const char *path,
662                                         const struct stage_data *stage_data)
663 {
664         struct diff_filespec o, a, b;
665
666         o.mode = stage_data->stages[1].mode;
667         oidcpy(&o.oid, &stage_data->stages[1].oid);
668
669         a.mode = stage_data->stages[2].mode;
670         oidcpy(&a.oid, &stage_data->stages[2].oid);
671
672         b.mode = stage_data->stages[3].mode;
673         oidcpy(&b.oid, &stage_data->stages[3].oid);
674
675         return update_stages(opt, path,
676                              is_null_oid(&o.oid) ? NULL : &o,
677                              is_null_oid(&a.oid) ? NULL : &a,
678                              is_null_oid(&b.oid) ? NULL : &b);
679 }
680
681 static void update_entry(struct stage_data *entry,
682                          struct diff_filespec *o,
683                          struct diff_filespec *a,
684                          struct diff_filespec *b)
685 {
686         entry->processed = 0;
687         entry->stages[1].mode = o->mode;
688         entry->stages[2].mode = a->mode;
689         entry->stages[3].mode = b->mode;
690         oidcpy(&entry->stages[1].oid, &o->oid);
691         oidcpy(&entry->stages[2].oid, &a->oid);
692         oidcpy(&entry->stages[3].oid, &b->oid);
693 }
694
695 static int remove_file(struct merge_options *o, int clean,
696                        const char *path, int no_wd)
697 {
698         int update_cache = o->call_depth || clean;
699         int update_working_directory = !o->call_depth && !no_wd;
700
701         if (update_cache) {
702                 if (remove_file_from_cache(path))
703                         return -1;
704         }
705         if (update_working_directory) {
706                 if (ignore_case) {
707                         struct cache_entry *ce;
708                         ce = cache_file_exists(path, strlen(path), ignore_case);
709                         if (ce && ce_stage(ce) == 0 && strcmp(path, ce->name))
710                                 return 0;
711                 }
712                 if (remove_path(path))
713                         return -1;
714         }
715         return 0;
716 }
717
718 /* add a string to a strbuf, but converting "/" to "_" */
719 static void add_flattened_path(struct strbuf *out, const char *s)
720 {
721         size_t i = out->len;
722         strbuf_addstr(out, s);
723         for (; i < out->len; i++)
724                 if (out->buf[i] == '/')
725                         out->buf[i] = '_';
726 }
727
728 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
729 {
730         struct path_hashmap_entry *entry;
731         struct strbuf newpath = STRBUF_INIT;
732         int suffix = 0;
733         size_t base_len;
734
735         strbuf_addf(&newpath, "%s~", path);
736         add_flattened_path(&newpath, branch);
737
738         base_len = newpath.len;
739         while (hashmap_get_from_hash(&o->current_file_dir_set,
740                                      path_hash(newpath.buf), newpath.buf) ||
741                (!o->call_depth && file_exists(newpath.buf))) {
742                 strbuf_setlen(&newpath, base_len);
743                 strbuf_addf(&newpath, "_%d", suffix++);
744         }
745
746         FLEX_ALLOC_MEM(entry, path, newpath.buf, newpath.len);
747         hashmap_entry_init(entry, path_hash(entry->path));
748         hashmap_add(&o->current_file_dir_set, entry);
749         return strbuf_detach(&newpath, NULL);
750 }
751
752 /**
753  * Check whether a directory in the index is in the way of an incoming
754  * file.  Return 1 if so.  If check_working_copy is non-zero, also
755  * check the working directory.  If empty_ok is non-zero, also return
756  * 0 in the case where the working-tree dir exists but is empty.
757  */
758 static int dir_in_way(const char *path, int check_working_copy, int empty_ok)
759 {
760         int pos;
761         struct strbuf dirpath = STRBUF_INIT;
762         struct stat st;
763
764         strbuf_addstr(&dirpath, path);
765         strbuf_addch(&dirpath, '/');
766
767         pos = cache_name_pos(dirpath.buf, dirpath.len);
768
769         if (pos < 0)
770                 pos = -1 - pos;
771         if (pos < active_nr &&
772             !strncmp(dirpath.buf, active_cache[pos]->name, dirpath.len)) {
773                 strbuf_release(&dirpath);
774                 return 1;
775         }
776
777         strbuf_release(&dirpath);
778         return check_working_copy && !lstat(path, &st) && S_ISDIR(st.st_mode) &&
779                 !(empty_ok && is_empty_dir(path));
780 }
781
782 /*
783  * Returns whether path was tracked in the index before the merge started,
784  * and its oid and mode match the specified values
785  */
786 static int was_tracked_and_matches(struct merge_options *o, const char *path,
787                                    const struct object_id *oid, unsigned mode)
788 {
789         int pos = index_name_pos(&o->orig_index, path, strlen(path));
790         struct cache_entry *ce;
791
792         if (0 > pos)
793                 /* we were not tracking this path before the merge */
794                 return 0;
795
796         /* See if the file we were tracking before matches */
797         ce = o->orig_index.cache[pos];
798         return (oid_eq(&ce->oid, oid) && ce->ce_mode == mode);
799 }
800
801 /*
802  * Returns whether path was tracked in the index before the merge started
803  */
804 static int was_tracked(struct merge_options *o, const char *path)
805 {
806         int pos = index_name_pos(&o->orig_index, path, strlen(path));
807
808         if (0 <= pos)
809                 /* we were tracking this path before the merge */
810                 return 1;
811
812         return 0;
813 }
814
815 static int would_lose_untracked(const char *path)
816 {
817         /*
818          * This may look like it can be simplified to:
819          *   return !was_tracked(o, path) && file_exists(path)
820          * but it can't.  This function needs to know whether path was in
821          * the working tree due to EITHER having been tracked in the index
822          * before the merge OR having been put into the working copy and
823          * index by unpack_trees().  Due to that either-or requirement, we
824          * check the current index instead of the original one.
825          *
826          * Note that we do not need to worry about merge-recursive itself
827          * updating the index after unpack_trees() and before calling this
828          * function, because we strictly require all code paths in
829          * merge-recursive to update the working tree first and the index
830          * second.  Doing otherwise would break
831          * update_file()/would_lose_untracked(); see every comment in this
832          * file which mentions "update_stages".
833          */
834         int pos = cache_name_pos(path, strlen(path));
835
836         if (pos < 0)
837                 pos = -1 - pos;
838         while (pos < active_nr &&
839                !strcmp(path, active_cache[pos]->name)) {
840                 /*
841                  * If stage #0, it is definitely tracked.
842                  * If it has stage #2 then it was tracked
843                  * before this merge started.  All other
844                  * cases the path was not tracked.
845                  */
846                 switch (ce_stage(active_cache[pos])) {
847                 case 0:
848                 case 2:
849                         return 0;
850                 }
851                 pos++;
852         }
853         return file_exists(path);
854 }
855
856 static int was_dirty(struct merge_options *o, const char *path)
857 {
858         struct cache_entry *ce;
859         int dirty = 1;
860
861         if (o->call_depth || !was_tracked(o, path))
862                 return !dirty;
863
864         ce = index_file_exists(o->unpack_opts.src_index,
865                                path, strlen(path), ignore_case);
866         dirty = verify_uptodate(ce, &o->unpack_opts) != 0;
867         return dirty;
868 }
869
870 static int make_room_for_path(struct merge_options *o, const char *path)
871 {
872         int status, i;
873         const char *msg = _("failed to create path '%s'%s");
874
875         /* Unlink any D/F conflict files that are in the way */
876         for (i = 0; i < o->df_conflict_file_set.nr; i++) {
877                 const char *df_path = o->df_conflict_file_set.items[i].string;
878                 size_t pathlen = strlen(path);
879                 size_t df_pathlen = strlen(df_path);
880                 if (df_pathlen < pathlen &&
881                     path[df_pathlen] == '/' &&
882                     strncmp(path, df_path, df_pathlen) == 0) {
883                         output(o, 3,
884                                _("Removing %s to make room for subdirectory\n"),
885                                df_path);
886                         unlink(df_path);
887                         unsorted_string_list_delete_item(&o->df_conflict_file_set,
888                                                          i, 0);
889                         break;
890                 }
891         }
892
893         /* Make sure leading directories are created */
894         status = safe_create_leading_directories_const(path);
895         if (status) {
896                 if (status == SCLD_EXISTS)
897                         /* something else exists */
898                         return err(o, msg, path, _(": perhaps a D/F conflict?"));
899                 return err(o, msg, path, "");
900         }
901
902         /*
903          * Do not unlink a file in the work tree if we are not
904          * tracking it.
905          */
906         if (would_lose_untracked(path))
907                 return err(o, _("refusing to lose untracked file at '%s'"),
908                              path);
909
910         /* Successful unlink is good.. */
911         if (!unlink(path))
912                 return 0;
913         /* .. and so is no existing file */
914         if (errno == ENOENT)
915                 return 0;
916         /* .. but not some other error (who really cares what?) */
917         return err(o, msg, path, _(": perhaps a D/F conflict?"));
918 }
919
920 static int update_file_flags(struct merge_options *o,
921                              const struct object_id *oid,
922                              unsigned mode,
923                              const char *path,
924                              int update_cache,
925                              int update_wd)
926 {
927         int ret = 0;
928
929         if (o->call_depth)
930                 update_wd = 0;
931
932         if (update_wd) {
933                 enum object_type type;
934                 void *buf;
935                 unsigned long size;
936
937                 if (S_ISGITLINK(mode)) {
938                         /*
939                          * We may later decide to recursively descend into
940                          * the submodule directory and update its index
941                          * and/or work tree, but we do not do that now.
942                          */
943                         update_wd = 0;
944                         goto update_index;
945                 }
946
947                 buf = read_object_file(oid, &type, &size);
948                 if (!buf)
949                         return err(o, _("cannot read object %s '%s'"), oid_to_hex(oid), path);
950                 if (type != OBJ_BLOB) {
951                         ret = err(o, _("blob expected for %s '%s'"), oid_to_hex(oid), path);
952                         goto free_buf;
953                 }
954                 if (S_ISREG(mode)) {
955                         struct strbuf strbuf = STRBUF_INIT;
956                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
957                                 free(buf);
958                                 size = strbuf.len;
959                                 buf = strbuf_detach(&strbuf, NULL);
960                         }
961                 }
962
963                 if (make_room_for_path(o, path) < 0) {
964                         update_wd = 0;
965                         goto free_buf;
966                 }
967                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
968                         int fd;
969                         if (mode & 0100)
970                                 mode = 0777;
971                         else
972                                 mode = 0666;
973                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
974                         if (fd < 0) {
975                                 ret = err(o, _("failed to open '%s': %s"),
976                                           path, strerror(errno));
977                                 goto free_buf;
978                         }
979                         write_in_full(fd, buf, size);
980                         close(fd);
981                 } else if (S_ISLNK(mode)) {
982                         char *lnk = xmemdupz(buf, size);
983                         safe_create_leading_directories_const(path);
984                         unlink(path);
985                         if (symlink(lnk, path))
986                                 ret = err(o, _("failed to symlink '%s': %s"),
987                                         path, strerror(errno));
988                         free(lnk);
989                 } else
990                         ret = err(o,
991                                   _("do not know what to do with %06o %s '%s'"),
992                                   mode, oid_to_hex(oid), path);
993  free_buf:
994                 free(buf);
995         }
996  update_index:
997         if (!ret && update_cache)
998                 if (add_cacheinfo(o, mode, oid, path, 0, update_wd,
999                                   ADD_CACHE_OK_TO_ADD))
1000                         return -1;
1001         return ret;
1002 }
1003
1004 static int update_file(struct merge_options *o,
1005                        int clean,
1006                        const struct object_id *oid,
1007                        unsigned mode,
1008                        const char *path)
1009 {
1010         return update_file_flags(o, oid, mode, path, o->call_depth || clean, !o->call_depth);
1011 }
1012
1013 /* Low level file merging, update and removal */
1014
1015 struct merge_file_info {
1016         struct object_id oid;
1017         unsigned mode;
1018         unsigned clean:1,
1019                  merge:1;
1020 };
1021
1022 static int merge_3way(struct merge_options *o,
1023                       mmbuffer_t *result_buf,
1024                       const struct diff_filespec *one,
1025                       const struct diff_filespec *a,
1026                       const struct diff_filespec *b,
1027                       const char *branch1,
1028                       const char *branch2)
1029 {
1030         mmfile_t orig, src1, src2;
1031         struct ll_merge_options ll_opts = {0};
1032         char *base_name, *name1, *name2;
1033         int merge_status;
1034
1035         ll_opts.renormalize = o->renormalize;
1036         ll_opts.xdl_opts = o->xdl_opts;
1037
1038         if (o->call_depth) {
1039                 ll_opts.virtual_ancestor = 1;
1040                 ll_opts.variant = 0;
1041         } else {
1042                 switch (o->recursive_variant) {
1043                 case MERGE_RECURSIVE_OURS:
1044                         ll_opts.variant = XDL_MERGE_FAVOR_OURS;
1045                         break;
1046                 case MERGE_RECURSIVE_THEIRS:
1047                         ll_opts.variant = XDL_MERGE_FAVOR_THEIRS;
1048                         break;
1049                 default:
1050                         ll_opts.variant = 0;
1051                         break;
1052                 }
1053         }
1054
1055         if (strcmp(a->path, b->path) ||
1056             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
1057                 base_name = o->ancestor == NULL ? NULL :
1058                         mkpathdup("%s:%s", o->ancestor, one->path);
1059                 name1 = mkpathdup("%s:%s", branch1, a->path);
1060                 name2 = mkpathdup("%s:%s", branch2, b->path);
1061         } else {
1062                 base_name = o->ancestor == NULL ? NULL :
1063                         mkpathdup("%s", o->ancestor);
1064                 name1 = mkpathdup("%s", branch1);
1065                 name2 = mkpathdup("%s", branch2);
1066         }
1067
1068         read_mmblob(&orig, &one->oid);
1069         read_mmblob(&src1, &a->oid);
1070         read_mmblob(&src2, &b->oid);
1071
1072         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
1073                                 &src1, name1, &src2, name2, &ll_opts);
1074
1075         free(base_name);
1076         free(name1);
1077         free(name2);
1078         free(orig.ptr);
1079         free(src1.ptr);
1080         free(src2.ptr);
1081         return merge_status;
1082 }
1083
1084 static int merge_file_1(struct merge_options *o,
1085                         const struct diff_filespec *one,
1086                         const struct diff_filespec *a,
1087                         const struct diff_filespec *b,
1088                         const char *filename,
1089                         const char *branch1,
1090                         const char *branch2,
1091                         struct merge_file_info *result)
1092 {
1093         result->merge = 0;
1094         result->clean = 1;
1095
1096         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
1097                 result->clean = 0;
1098                 if (S_ISREG(a->mode)) {
1099                         result->mode = a->mode;
1100                         oidcpy(&result->oid, &a->oid);
1101                 } else {
1102                         result->mode = b->mode;
1103                         oidcpy(&result->oid, &b->oid);
1104                 }
1105         } else {
1106                 if (!oid_eq(&a->oid, &one->oid) && !oid_eq(&b->oid, &one->oid))
1107                         result->merge = 1;
1108
1109                 /*
1110                  * Merge modes
1111                  */
1112                 if (a->mode == b->mode || a->mode == one->mode)
1113                         result->mode = b->mode;
1114                 else {
1115                         result->mode = a->mode;
1116                         if (b->mode != one->mode) {
1117                                 result->clean = 0;
1118                                 result->merge = 1;
1119                         }
1120                 }
1121
1122                 if (oid_eq(&a->oid, &b->oid) || oid_eq(&a->oid, &one->oid))
1123                         oidcpy(&result->oid, &b->oid);
1124                 else if (oid_eq(&b->oid, &one->oid))
1125                         oidcpy(&result->oid, &a->oid);
1126                 else if (S_ISREG(a->mode)) {
1127                         mmbuffer_t result_buf;
1128                         int ret = 0, merge_status;
1129
1130                         merge_status = merge_3way(o, &result_buf, one, a, b,
1131                                                   branch1, branch2);
1132
1133                         if ((merge_status < 0) || !result_buf.ptr)
1134                                 ret = err(o, _("Failed to execute internal merge"));
1135
1136                         if (!ret &&
1137                             write_object_file(result_buf.ptr, result_buf.size,
1138                                               blob_type, &result->oid))
1139                                 ret = err(o, _("Unable to add %s to database"),
1140                                           a->path);
1141
1142                         free(result_buf.ptr);
1143                         if (ret)
1144                                 return ret;
1145                         result->clean = (merge_status == 0);
1146                 } else if (S_ISGITLINK(a->mode)) {
1147                         result->clean = merge_submodule(&result->oid,
1148                                                        one->path,
1149                                                        &one->oid,
1150                                                        &a->oid,
1151                                                        &b->oid,
1152                                                        !o->call_depth);
1153                 } else if (S_ISLNK(a->mode)) {
1154                         switch (o->recursive_variant) {
1155                         case MERGE_RECURSIVE_NORMAL:
1156                                 oidcpy(&result->oid, &a->oid);
1157                                 if (!oid_eq(&a->oid, &b->oid))
1158                                         result->clean = 0;
1159                                 break;
1160                         case MERGE_RECURSIVE_OURS:
1161                                 oidcpy(&result->oid, &a->oid);
1162                                 break;
1163                         case MERGE_RECURSIVE_THEIRS:
1164                                 oidcpy(&result->oid, &b->oid);
1165                                 break;
1166                         }
1167                 } else
1168                         die("BUG: unsupported object type in the tree");
1169         }
1170
1171         if (result->merge)
1172                 output(o, 2, _("Auto-merging %s"), filename);
1173
1174         return 0;
1175 }
1176
1177 static int merge_file_special_markers(struct merge_options *o,
1178                                       const struct diff_filespec *one,
1179                                       const struct diff_filespec *a,
1180                                       const struct diff_filespec *b,
1181                                       const char *target_filename,
1182                                       const char *branch1,
1183                                       const char *filename1,
1184                                       const char *branch2,
1185                                       const char *filename2,
1186                                       struct merge_file_info *mfi)
1187 {
1188         char *side1 = NULL;
1189         char *side2 = NULL;
1190         int ret;
1191
1192         if (filename1)
1193                 side1 = xstrfmt("%s:%s", branch1, filename1);
1194         if (filename2)
1195                 side2 = xstrfmt("%s:%s", branch2, filename2);
1196
1197         ret = merge_file_1(o, one, a, b, target_filename,
1198                            side1 ? side1 : branch1,
1199                            side2 ? side2 : branch2, mfi);
1200
1201         free(side1);
1202         free(side2);
1203         return ret;
1204 }
1205
1206 static int merge_file_one(struct merge_options *o,
1207                           const char *path,
1208                           const struct object_id *o_oid, int o_mode,
1209                           const struct object_id *a_oid, int a_mode,
1210                           const struct object_id *b_oid, int b_mode,
1211                           const char *branch1,
1212                           const char *branch2,
1213                           struct merge_file_info *mfi)
1214 {
1215         struct diff_filespec one, a, b;
1216
1217         one.path = a.path = b.path = (char *)path;
1218         oidcpy(&one.oid, o_oid);
1219         one.mode = o_mode;
1220         oidcpy(&a.oid, a_oid);
1221         a.mode = a_mode;
1222         oidcpy(&b.oid, b_oid);
1223         b.mode = b_mode;
1224         return merge_file_1(o, &one, &a, &b, path, branch1, branch2, mfi);
1225 }
1226
1227 static int conflict_rename_dir(struct merge_options *o,
1228                                struct diff_filepair *pair,
1229                                const char *rename_branch,
1230                                const char *other_branch)
1231 {
1232         const struct diff_filespec *dest = pair->two;
1233
1234         if (!o->call_depth && would_lose_untracked(dest->path)) {
1235                 char *alt_path = unique_path(o, dest->path, rename_branch);
1236
1237                 output(o, 1, _("Error: Refusing to lose untracked file at %s; "
1238                                "writing to %s instead."),
1239                        dest->path, alt_path);
1240                 /*
1241                  * Write the file in worktree at alt_path, but not in the
1242                  * index.  Instead, write to dest->path for the index but
1243                  * only at the higher appropriate stage.
1244                  */
1245                 if (update_file(o, 0, &dest->oid, dest->mode, alt_path))
1246                         return -1;
1247                 free(alt_path);
1248                 return update_stages(o, dest->path, NULL,
1249                                      rename_branch == o->branch1 ? dest : NULL,
1250                                      rename_branch == o->branch1 ? NULL : dest);
1251         }
1252
1253         /* Update dest->path both in index and in worktree */
1254         if (update_file(o, 1, &dest->oid, dest->mode, dest->path))
1255                 return -1;
1256         return 0;
1257 }
1258
1259 static int handle_change_delete(struct merge_options *o,
1260                                  const char *path, const char *old_path,
1261                                  const struct object_id *o_oid, int o_mode,
1262                                  const struct object_id *changed_oid,
1263                                  int changed_mode,
1264                                  const char *change_branch,
1265                                  const char *delete_branch,
1266                                  const char *change, const char *change_past)
1267 {
1268         char *alt_path = NULL;
1269         const char *update_path = path;
1270         int ret = 0;
1271
1272         if (dir_in_way(path, !o->call_depth, 0) ||
1273             (!o->call_depth && would_lose_untracked(path))) {
1274                 update_path = alt_path = unique_path(o, path, change_branch);
1275         }
1276
1277         if (o->call_depth) {
1278                 /*
1279                  * We cannot arbitrarily accept either a_sha or b_sha as
1280                  * correct; since there is no true "middle point" between
1281                  * them, simply reuse the base version for virtual merge base.
1282                  */
1283                 ret = remove_file_from_cache(path);
1284                 if (!ret)
1285                         ret = update_file(o, 0, o_oid, o_mode, update_path);
1286         } else {
1287                 if (!alt_path) {
1288                         if (!old_path) {
1289                                 output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1290                                        "and %s in %s. Version %s of %s left in tree."),
1291                                        change, path, delete_branch, change_past,
1292                                        change_branch, change_branch, path);
1293                         } else {
1294                                 output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1295                                        "and %s to %s in %s. Version %s of %s left in tree."),
1296                                        change, old_path, delete_branch, change_past, path,
1297                                        change_branch, change_branch, path);
1298                         }
1299                 } else {
1300                         if (!old_path) {
1301                                 output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1302                                        "and %s in %s. Version %s of %s left in tree at %s."),
1303                                        change, path, delete_branch, change_past,
1304                                        change_branch, change_branch, path, alt_path);
1305                         } else {
1306                                 output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1307                                        "and %s to %s in %s. Version %s of %s left in tree at %s."),
1308                                        change, old_path, delete_branch, change_past, path,
1309                                        change_branch, change_branch, path, alt_path);
1310                         }
1311                 }
1312                 /*
1313                  * No need to call update_file() on path when change_branch ==
1314                  * o->branch1 && !alt_path, since that would needlessly touch
1315                  * path.  We could call update_file_flags() with update_cache=0
1316                  * and update_wd=0, but that's a no-op.
1317                  */
1318                 if (change_branch != o->branch1 || alt_path)
1319                         ret = update_file(o, 0, changed_oid, changed_mode, update_path);
1320         }
1321         free(alt_path);
1322
1323         return ret;
1324 }
1325
1326 static int conflict_rename_delete(struct merge_options *o,
1327                                    struct diff_filepair *pair,
1328                                    const char *rename_branch,
1329                                    const char *delete_branch)
1330 {
1331         const struct diff_filespec *orig = pair->one;
1332         const struct diff_filespec *dest = pair->two;
1333
1334         if (handle_change_delete(o,
1335                                  o->call_depth ? orig->path : dest->path,
1336                                  o->call_depth ? NULL : orig->path,
1337                                  &orig->oid, orig->mode,
1338                                  &dest->oid, dest->mode,
1339                                  rename_branch, delete_branch,
1340                                  _("rename"), _("renamed")))
1341                 return -1;
1342
1343         if (o->call_depth)
1344                 return remove_file_from_cache(dest->path);
1345         else
1346                 return update_stages(o, dest->path, NULL,
1347                                      rename_branch == o->branch1 ? dest : NULL,
1348                                      rename_branch == o->branch1 ? NULL : dest);
1349 }
1350
1351 static struct diff_filespec *filespec_from_entry(struct diff_filespec *target,
1352                                                  struct stage_data *entry,
1353                                                  int stage)
1354 {
1355         struct object_id *oid = &entry->stages[stage].oid;
1356         unsigned mode = entry->stages[stage].mode;
1357         if (mode == 0 || is_null_oid(oid))
1358                 return NULL;
1359         oidcpy(&target->oid, oid);
1360         target->mode = mode;
1361         return target;
1362 }
1363
1364 static int handle_file(struct merge_options *o,
1365                         struct diff_filespec *rename,
1366                         int stage,
1367                         struct rename_conflict_info *ci)
1368 {
1369         char *dst_name = rename->path;
1370         struct stage_data *dst_entry;
1371         const char *cur_branch, *other_branch;
1372         struct diff_filespec other;
1373         struct diff_filespec *add;
1374         int ret;
1375
1376         if (stage == 2) {
1377                 dst_entry = ci->dst_entry1;
1378                 cur_branch = ci->branch1;
1379                 other_branch = ci->branch2;
1380         } else {
1381                 dst_entry = ci->dst_entry2;
1382                 cur_branch = ci->branch2;
1383                 other_branch = ci->branch1;
1384         }
1385
1386         add = filespec_from_entry(&other, dst_entry, stage ^ 1);
1387         if (add) {
1388                 int ren_src_was_dirty = was_dirty(o, rename->path);
1389                 char *add_name = unique_path(o, rename->path, other_branch);
1390                 if (update_file(o, 0, &add->oid, add->mode, add_name))
1391                         return -1;
1392
1393                 if (ren_src_was_dirty) {
1394                         output(o, 1, _("Refusing to lose dirty file at %s"),
1395                                rename->path);
1396                 }
1397                 /*
1398                  * Because the double negatives somehow keep confusing me...
1399                  *    1) update_wd iff !ren_src_was_dirty.
1400                  *    2) no_wd iff !update_wd
1401                  *    3) so, no_wd == !!ren_src_was_dirty == ren_src_was_dirty
1402                  */
1403                 remove_file(o, 0, rename->path, ren_src_was_dirty);
1404                 dst_name = unique_path(o, rename->path, cur_branch);
1405         } else {
1406                 if (dir_in_way(rename->path, !o->call_depth, 0)) {
1407                         dst_name = unique_path(o, rename->path, cur_branch);
1408                         output(o, 1, _("%s is a directory in %s adding as %s instead"),
1409                                rename->path, other_branch, dst_name);
1410                 } else if (!o->call_depth &&
1411                            would_lose_untracked(rename->path)) {
1412                         dst_name = unique_path(o, rename->path, cur_branch);
1413                         output(o, 1, _("Refusing to lose untracked file at %s; "
1414                                        "adding as %s instead"),
1415                                rename->path, dst_name);
1416                 }
1417         }
1418         if ((ret = update_file(o, 0, &rename->oid, rename->mode, dst_name)))
1419                 ; /* fall through, do allow dst_name to be released */
1420         else if (stage == 2)
1421                 ret = update_stages(o, rename->path, NULL, rename, add);
1422         else
1423                 ret = update_stages(o, rename->path, NULL, add, rename);
1424
1425         if (dst_name != rename->path)
1426                 free(dst_name);
1427
1428         return ret;
1429 }
1430
1431 static int conflict_rename_rename_1to2(struct merge_options *o,
1432                                         struct rename_conflict_info *ci)
1433 {
1434         /* One file was renamed in both branches, but to different names. */
1435         struct diff_filespec *one = ci->pair1->one;
1436         struct diff_filespec *a = ci->pair1->two;
1437         struct diff_filespec *b = ci->pair2->two;
1438
1439         output(o, 1, _("CONFLICT (rename/rename): "
1440                "Rename \"%s\"->\"%s\" in branch \"%s\" "
1441                "rename \"%s\"->\"%s\" in \"%s\"%s"),
1442                one->path, a->path, ci->branch1,
1443                one->path, b->path, ci->branch2,
1444                o->call_depth ? _(" (left unresolved)") : "");
1445         if (o->call_depth) {
1446                 struct merge_file_info mfi;
1447                 struct diff_filespec other;
1448                 struct diff_filespec *add;
1449                 if (merge_file_one(o, one->path,
1450                                  &one->oid, one->mode,
1451                                  &a->oid, a->mode,
1452                                  &b->oid, b->mode,
1453                                  ci->branch1, ci->branch2, &mfi))
1454                         return -1;
1455
1456                 /*
1457                  * FIXME: For rename/add-source conflicts (if we could detect
1458                  * such), this is wrong.  We should instead find a unique
1459                  * pathname and then either rename the add-source file to that
1460                  * unique path, or use that unique path instead of src here.
1461                  */
1462                 if (update_file(o, 0, &mfi.oid, mfi.mode, one->path))
1463                         return -1;
1464
1465                 /*
1466                  * Above, we put the merged content at the merge-base's
1467                  * path.  Now we usually need to delete both a->path and
1468                  * b->path.  However, the rename on each side of the merge
1469                  * could also be involved in a rename/add conflict.  In
1470                  * such cases, we should keep the added file around,
1471                  * resolving the conflict at that path in its favor.
1472                  */
1473                 add = filespec_from_entry(&other, ci->dst_entry1, 2 ^ 1);
1474                 if (add) {
1475                         if (update_file(o, 0, &add->oid, add->mode, a->path))
1476                                 return -1;
1477                 }
1478                 else
1479                         remove_file_from_cache(a->path);
1480                 add = filespec_from_entry(&other, ci->dst_entry2, 3 ^ 1);
1481                 if (add) {
1482                         if (update_file(o, 0, &add->oid, add->mode, b->path))
1483                                 return -1;
1484                 }
1485                 else
1486                         remove_file_from_cache(b->path);
1487         } else if (handle_file(o, a, 2, ci) || handle_file(o, b, 3, ci))
1488                 return -1;
1489
1490         return 0;
1491 }
1492
1493 static int conflict_rename_rename_2to1(struct merge_options *o,
1494                                         struct rename_conflict_info *ci)
1495 {
1496         /* Two files, a & b, were renamed to the same thing, c. */
1497         struct diff_filespec *a = ci->pair1->one;
1498         struct diff_filespec *b = ci->pair2->one;
1499         struct diff_filespec *c1 = ci->pair1->two;
1500         struct diff_filespec *c2 = ci->pair2->two;
1501         char *path = c1->path; /* == c2->path */
1502         char *path_side_1_desc;
1503         char *path_side_2_desc;
1504         struct merge_file_info mfi_c1;
1505         struct merge_file_info mfi_c2;
1506         int ret;
1507
1508         output(o, 1, _("CONFLICT (rename/rename): "
1509                "Rename %s->%s in %s. "
1510                "Rename %s->%s in %s"),
1511                a->path, c1->path, ci->branch1,
1512                b->path, c2->path, ci->branch2);
1513
1514         remove_file(o, 1, a->path, o->call_depth || would_lose_untracked(a->path));
1515         remove_file(o, 1, b->path, o->call_depth || would_lose_untracked(b->path));
1516
1517         path_side_1_desc = xstrfmt("%s (was %s)", path, a->path);
1518         path_side_2_desc = xstrfmt("%s (was %s)", path, b->path);
1519         if (merge_file_special_markers(o, a, c1, &ci->ren1_other,
1520                                        path_side_1_desc,
1521                                        o->branch1, c1->path,
1522                                        o->branch2, ci->ren1_other.path, &mfi_c1) ||
1523             merge_file_special_markers(o, b, &ci->ren2_other, c2,
1524                                        path_side_2_desc,
1525                                        o->branch1, ci->ren2_other.path,
1526                                        o->branch2, c2->path, &mfi_c2))
1527                 return -1;
1528         free(path_side_1_desc);
1529         free(path_side_2_desc);
1530
1531         if (o->call_depth) {
1532                 /*
1533                  * If mfi_c1.clean && mfi_c2.clean, then it might make
1534                  * sense to do a two-way merge of those results.  But, I
1535                  * think in all cases, it makes sense to have the virtual
1536                  * merge base just undo the renames; they can be detected
1537                  * again later for the non-recursive merge.
1538                  */
1539                 remove_file(o, 0, path, 0);
1540                 ret = update_file(o, 0, &mfi_c1.oid, mfi_c1.mode, a->path);
1541                 if (!ret)
1542                         ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
1543                                           b->path);
1544         } else {
1545                 char *new_path1 = unique_path(o, path, ci->branch1);
1546                 char *new_path2 = unique_path(o, path, ci->branch2);
1547                 output(o, 1, _("Renaming %s to %s and %s to %s instead"),
1548                        a->path, new_path1, b->path, new_path2);
1549                 if (was_dirty(o, path))
1550                         output(o, 1, _("Refusing to lose dirty file at %s"),
1551                                path);
1552                 else if (would_lose_untracked(path))
1553                         /*
1554                          * Only way we get here is if both renames were from
1555                          * a directory rename AND user had an untracked file
1556                          * at the location where both files end up after the
1557                          * two directory renames.  See testcase 10d of t6043.
1558                          */
1559                         output(o, 1, _("Refusing to lose untracked file at "
1560                                        "%s, even though it's in the way."),
1561                                path);
1562                 else
1563                         remove_file(o, 0, path, 0);
1564                 ret = update_file(o, 0, &mfi_c1.oid, mfi_c1.mode, new_path1);
1565                 if (!ret)
1566                         ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
1567                                           new_path2);
1568                 /*
1569                  * unpack_trees() actually populates the index for us for
1570                  * "normal" rename/rename(2to1) situtations so that the
1571                  * correct entries are at the higher stages, which would
1572                  * make the call below to update_stages_for_stage_data
1573                  * unnecessary.  However, if either of the renames came
1574                  * from a directory rename, then unpack_trees() will not
1575                  * have gotten the right data loaded into the index, so we
1576                  * need to do so now.  (While it'd be tempting to move this
1577                  * call to update_stages_for_stage_data() to
1578                  * apply_directory_rename_modifications(), that would break
1579                  * our intermediate calls to would_lose_untracked() since
1580                  * those rely on the current in-memory index.  See also the
1581                  * big "NOTE" in update_stages()).
1582                  */
1583                 if (update_stages_for_stage_data(o, path, ci->dst_entry1))
1584                         ret = -1;
1585
1586                 free(new_path2);
1587                 free(new_path1);
1588         }
1589
1590         return ret;
1591 }
1592
1593 /*
1594  * Get the diff_filepairs changed between o_tree and tree.
1595  */
1596 static struct diff_queue_struct *get_diffpairs(struct merge_options *o,
1597                                                struct tree *o_tree,
1598                                                struct tree *tree)
1599 {
1600         struct diff_queue_struct *ret;
1601         struct diff_options opts;
1602
1603         diff_setup(&opts);
1604         opts.flags.recursive = 1;
1605         opts.flags.rename_empty = 0;
1606         opts.detect_rename = DIFF_DETECT_RENAME;
1607         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
1608                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
1609                             1000;
1610         opts.rename_score = o->rename_score;
1611         opts.show_rename_progress = o->show_rename_progress;
1612         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
1613         diff_setup_done(&opts);
1614         diff_tree_oid(&o_tree->object.oid, &tree->object.oid, "", &opts);
1615         diffcore_std(&opts);
1616         if (opts.needed_rename_limit > o->needed_rename_limit)
1617                 o->needed_rename_limit = opts.needed_rename_limit;
1618
1619         ret = xmalloc(sizeof(*ret));
1620         *ret = diff_queued_diff;
1621
1622         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
1623         diff_queued_diff.nr = 0;
1624         diff_queued_diff.queue = NULL;
1625         diff_flush(&opts);
1626         return ret;
1627 }
1628
1629 static int tree_has_path(struct tree *tree, const char *path)
1630 {
1631         struct object_id hashy;
1632         unsigned int mode_o;
1633
1634         return !get_tree_entry(&tree->object.oid, path,
1635                                &hashy, &mode_o);
1636 }
1637
1638 /*
1639  * Return a new string that replaces the beginning portion (which matches
1640  * entry->dir), with entry->new_dir.  In perl-speak:
1641  *   new_path_name = (old_path =~ s/entry->dir/entry->new_dir/);
1642  * NOTE:
1643  *   Caller must ensure that old_path starts with entry->dir + '/'.
1644  */
1645 static char *apply_dir_rename(struct dir_rename_entry *entry,
1646                               const char *old_path)
1647 {
1648         struct strbuf new_path = STRBUF_INIT;
1649         int oldlen, newlen;
1650
1651         if (entry->non_unique_new_dir)
1652                 return NULL;
1653
1654         oldlen = strlen(entry->dir);
1655         newlen = entry->new_dir.len + (strlen(old_path) - oldlen) + 1;
1656         strbuf_grow(&new_path, newlen);
1657         strbuf_addbuf(&new_path, &entry->new_dir);
1658         strbuf_addstr(&new_path, &old_path[oldlen]);
1659
1660         return strbuf_detach(&new_path, NULL);
1661 }
1662
1663 static void get_renamed_dir_portion(const char *old_path, const char *new_path,
1664                                     char **old_dir, char **new_dir)
1665 {
1666         char *end_of_old, *end_of_new;
1667         int old_len, new_len;
1668
1669         *old_dir = NULL;
1670         *new_dir = NULL;
1671
1672         /*
1673          * For
1674          *    "a/b/c/d/e/foo.c" -> "a/b/some/thing/else/e/foo.c"
1675          * the "e/foo.c" part is the same, we just want to know that
1676          *    "a/b/c/d" was renamed to "a/b/some/thing/else"
1677          * so, for this example, this function returns "a/b/c/d" in
1678          * *old_dir and "a/b/some/thing/else" in *new_dir.
1679          *
1680          * Also, if the basename of the file changed, we don't care.  We
1681          * want to know which portion of the directory, if any, changed.
1682          */
1683         end_of_old = strrchr(old_path, '/');
1684         end_of_new = strrchr(new_path, '/');
1685
1686         if (end_of_old == NULL || end_of_new == NULL)
1687                 return;
1688         while (*--end_of_new == *--end_of_old &&
1689                end_of_old != old_path &&
1690                end_of_new != new_path)
1691                 ; /* Do nothing; all in the while loop */
1692         /*
1693          * We've found the first non-matching character in the directory
1694          * paths.  That means the current directory we were comparing
1695          * represents the rename.  Move end_of_old and end_of_new back
1696          * to the full directory name.
1697          */
1698         if (*end_of_old == '/')
1699                 end_of_old++;
1700         if (*end_of_old != '/')
1701                 end_of_new++;
1702         end_of_old = strchr(end_of_old, '/');
1703         end_of_new = strchr(end_of_new, '/');
1704
1705         /*
1706          * It may have been the case that old_path and new_path were the same
1707          * directory all along.  Don't claim a rename if they're the same.
1708          */
1709         old_len = end_of_old - old_path;
1710         new_len = end_of_new - new_path;
1711
1712         if (old_len != new_len || strncmp(old_path, new_path, old_len)) {
1713                 *old_dir = xstrndup(old_path, old_len);
1714                 *new_dir = xstrndup(new_path, new_len);
1715         }
1716 }
1717
1718 static void remove_hashmap_entries(struct hashmap *dir_renames,
1719                                    struct string_list *items_to_remove)
1720 {
1721         int i;
1722         struct dir_rename_entry *entry;
1723
1724         for (i = 0; i < items_to_remove->nr; i++) {
1725                 entry = items_to_remove->items[i].util;
1726                 hashmap_remove(dir_renames, entry, NULL);
1727         }
1728         string_list_clear(items_to_remove, 0);
1729 }
1730
1731 /*
1732  * See if there is a directory rename for path, and if there are any file
1733  * level conflicts for the renamed location.  If there is a rename and
1734  * there are no conflicts, return the new name.  Otherwise, return NULL.
1735  */
1736 static char *handle_path_level_conflicts(struct merge_options *o,
1737                                          const char *path,
1738                                          struct dir_rename_entry *entry,
1739                                          struct hashmap *collisions,
1740                                          struct tree *tree)
1741 {
1742         char *new_path = NULL;
1743         struct collision_entry *collision_ent;
1744         int clean = 1;
1745         struct strbuf collision_paths = STRBUF_INIT;
1746
1747         /*
1748          * entry has the mapping of old directory name to new directory name
1749          * that we want to apply to path.
1750          */
1751         new_path = apply_dir_rename(entry, path);
1752
1753         if (!new_path) {
1754                 /* This should only happen when entry->non_unique_new_dir set */
1755                 if (!entry->non_unique_new_dir)
1756                         BUG("entry->non_unqiue_dir not set and !new_path");
1757                 output(o, 1, _("CONFLICT (directory rename split): "
1758                                "Unclear where to place %s because directory "
1759                                "%s was renamed to multiple other directories, "
1760                                "with no destination getting a majority of the "
1761                                "files."),
1762                        path, entry->dir);
1763                 clean = 0;
1764                 return NULL;
1765         }
1766
1767         /*
1768          * The caller needs to have ensured that it has pre-populated
1769          * collisions with all paths that map to new_path.  Do a quick check
1770          * to ensure that's the case.
1771          */
1772         collision_ent = collision_find_entry(collisions, new_path);
1773         if (collision_ent == NULL)
1774                 BUG("collision_ent is NULL");
1775
1776         /*
1777          * Check for one-sided add/add/.../add conflicts, i.e.
1778          * where implicit renames from the other side doing
1779          * directory rename(s) can affect this side of history
1780          * to put multiple paths into the same location.  Warn
1781          * and bail on directory renames for such paths.
1782          */
1783         if (collision_ent->reported_already) {
1784                 clean = 0;
1785         } else if (tree_has_path(tree, new_path)) {
1786                 collision_ent->reported_already = 1;
1787                 strbuf_add_separated_string_list(&collision_paths, ", ",
1788                                                  &collision_ent->source_files);
1789                 output(o, 1, _("CONFLICT (implicit dir rename): Existing "
1790                                "file/dir at %s in the way of implicit "
1791                                "directory rename(s) putting the following "
1792                                "path(s) there: %s."),
1793                        new_path, collision_paths.buf);
1794                 clean = 0;
1795         } else if (collision_ent->source_files.nr > 1) {
1796                 collision_ent->reported_already = 1;
1797                 strbuf_add_separated_string_list(&collision_paths, ", ",
1798                                                  &collision_ent->source_files);
1799                 output(o, 1, _("CONFLICT (implicit dir rename): Cannot map "
1800                                "more than one path to %s; implicit directory "
1801                                "renames tried to put these paths there: %s"),
1802                        new_path, collision_paths.buf);
1803                 clean = 0;
1804         }
1805
1806         /* Free memory we no longer need */
1807         strbuf_release(&collision_paths);
1808         if (!clean && new_path) {
1809                 free(new_path);
1810                 return NULL;
1811         }
1812
1813         return new_path;
1814 }
1815
1816 /*
1817  * There are a couple things we want to do at the directory level:
1818  *   1. Check for both sides renaming to the same thing, in order to avoid
1819  *      implicit renaming of files that should be left in place.  (See
1820  *      testcase 6b in t6043 for details.)
1821  *   2. Prune directory renames if there are still files left in the
1822  *      the original directory.  These represent a partial directory rename,
1823  *      i.e. a rename where only some of the files within the directory
1824  *      were renamed elsewhere.  (Technically, this could be done earlier
1825  *      in get_directory_renames(), except that would prevent us from
1826  *      doing the previous check and thus failing testcase 6b.)
1827  *   3. Check for rename/rename(1to2) conflicts (at the directory level).
1828  *      In the future, we could potentially record this info as well and
1829  *      omit reporting rename/rename(1to2) conflicts for each path within
1830  *      the affected directories, thus cleaning up the merge output.
1831  *   NOTE: We do NOT check for rename/rename(2to1) conflicts at the
1832  *         directory level, because merging directories is fine.  If it
1833  *         causes conflicts for files within those merged directories, then
1834  *         that should be detected at the individual path level.
1835  */
1836 static void handle_directory_level_conflicts(struct merge_options *o,
1837                                              struct hashmap *dir_re_head,
1838                                              struct tree *head,
1839                                              struct hashmap *dir_re_merge,
1840                                              struct tree *merge)
1841 {
1842         struct hashmap_iter iter;
1843         struct dir_rename_entry *head_ent;
1844         struct dir_rename_entry *merge_ent;
1845
1846         struct string_list remove_from_head = STRING_LIST_INIT_NODUP;
1847         struct string_list remove_from_merge = STRING_LIST_INIT_NODUP;
1848
1849         hashmap_iter_init(dir_re_head, &iter);
1850         while ((head_ent = hashmap_iter_next(&iter))) {
1851                 merge_ent = dir_rename_find_entry(dir_re_merge, head_ent->dir);
1852                 if (merge_ent &&
1853                     !head_ent->non_unique_new_dir &&
1854                     !merge_ent->non_unique_new_dir &&
1855                     !strbuf_cmp(&head_ent->new_dir, &merge_ent->new_dir)) {
1856                         /* 1. Renamed identically; remove it from both sides */
1857                         string_list_append(&remove_from_head,
1858                                            head_ent->dir)->util = head_ent;
1859                         strbuf_release(&head_ent->new_dir);
1860                         string_list_append(&remove_from_merge,
1861                                            merge_ent->dir)->util = merge_ent;
1862                         strbuf_release(&merge_ent->new_dir);
1863                 } else if (tree_has_path(head, head_ent->dir)) {
1864                         /* 2. This wasn't a directory rename after all */
1865                         string_list_append(&remove_from_head,
1866                                            head_ent->dir)->util = head_ent;
1867                         strbuf_release(&head_ent->new_dir);
1868                 }
1869         }
1870
1871         remove_hashmap_entries(dir_re_head, &remove_from_head);
1872         remove_hashmap_entries(dir_re_merge, &remove_from_merge);
1873
1874         hashmap_iter_init(dir_re_merge, &iter);
1875         while ((merge_ent = hashmap_iter_next(&iter))) {
1876                 head_ent = dir_rename_find_entry(dir_re_head, merge_ent->dir);
1877                 if (tree_has_path(merge, merge_ent->dir)) {
1878                         /* 2. This wasn't a directory rename after all */
1879                         string_list_append(&remove_from_merge,
1880                                            merge_ent->dir)->util = merge_ent;
1881                 } else if (head_ent &&
1882                            !head_ent->non_unique_new_dir &&
1883                            !merge_ent->non_unique_new_dir) {
1884                         /* 3. rename/rename(1to2) */
1885                         /*
1886                          * We can assume it's not rename/rename(1to1) because
1887                          * that was case (1), already checked above.  So we
1888                          * know that head_ent->new_dir and merge_ent->new_dir
1889                          * are different strings.
1890                          */
1891                         output(o, 1, _("CONFLICT (rename/rename): "
1892                                        "Rename directory %s->%s in %s. "
1893                                        "Rename directory %s->%s in %s"),
1894                                head_ent->dir, head_ent->new_dir.buf, o->branch1,
1895                                head_ent->dir, merge_ent->new_dir.buf, o->branch2);
1896                         string_list_append(&remove_from_head,
1897                                            head_ent->dir)->util = head_ent;
1898                         strbuf_release(&head_ent->new_dir);
1899                         string_list_append(&remove_from_merge,
1900                                            merge_ent->dir)->util = merge_ent;
1901                         strbuf_release(&merge_ent->new_dir);
1902                 }
1903         }
1904
1905         remove_hashmap_entries(dir_re_head, &remove_from_head);
1906         remove_hashmap_entries(dir_re_merge, &remove_from_merge);
1907 }
1908
1909 static struct hashmap *get_directory_renames(struct diff_queue_struct *pairs,
1910                                              struct tree *tree)
1911 {
1912         struct hashmap *dir_renames;
1913         struct hashmap_iter iter;
1914         struct dir_rename_entry *entry;
1915         int i;
1916
1917         /*
1918          * Typically, we think of a directory rename as all files from a
1919          * certain directory being moved to a target directory.  However,
1920          * what if someone first moved two files from the original
1921          * directory in one commit, and then renamed the directory
1922          * somewhere else in a later commit?  At merge time, we just know
1923          * that files from the original directory went to two different
1924          * places, and that the bulk of them ended up in the same place.
1925          * We want each directory rename to represent where the bulk of the
1926          * files from that directory end up; this function exists to find
1927          * where the bulk of the files went.
1928          *
1929          * The first loop below simply iterates through the list of file
1930          * renames, finding out how often each directory rename pair
1931          * possibility occurs.
1932          */
1933         dir_renames = xmalloc(sizeof(*dir_renames));
1934         dir_rename_init(dir_renames);
1935         for (i = 0; i < pairs->nr; ++i) {
1936                 struct string_list_item *item;
1937                 int *count;
1938                 struct diff_filepair *pair = pairs->queue[i];
1939                 char *old_dir, *new_dir;
1940
1941                 /* File not part of directory rename if it wasn't renamed */
1942                 if (pair->status != 'R')
1943                         continue;
1944
1945                 get_renamed_dir_portion(pair->one->path, pair->two->path,
1946                                         &old_dir,        &new_dir);
1947                 if (!old_dir)
1948                         /* Directory didn't change at all; ignore this one. */
1949                         continue;
1950
1951                 entry = dir_rename_find_entry(dir_renames, old_dir);
1952                 if (!entry) {
1953                         entry = xmalloc(sizeof(*entry));
1954                         dir_rename_entry_init(entry, old_dir);
1955                         hashmap_put(dir_renames, entry);
1956                 } else {
1957                         free(old_dir);
1958                 }
1959                 item = string_list_lookup(&entry->possible_new_dirs, new_dir);
1960                 if (!item) {
1961                         item = string_list_insert(&entry->possible_new_dirs,
1962                                                   new_dir);
1963                         item->util = xcalloc(1, sizeof(int));
1964                 } else {
1965                         free(new_dir);
1966                 }
1967                 count = item->util;
1968                 *count += 1;
1969         }
1970
1971         /*
1972          * For each directory with files moved out of it, we find out which
1973          * target directory received the most files so we can declare it to
1974          * be the "winning" target location for the directory rename.  This
1975          * winner gets recorded in new_dir.  If there is no winner
1976          * (multiple target directories received the same number of files),
1977          * we set non_unique_new_dir.  Once we've determined the winner (or
1978          * that there is no winner), we no longer need possible_new_dirs.
1979          */
1980         hashmap_iter_init(dir_renames, &iter);
1981         while ((entry = hashmap_iter_next(&iter))) {
1982                 int max = 0;
1983                 int bad_max = 0;
1984                 char *best = NULL;
1985
1986                 for (i = 0; i < entry->possible_new_dirs.nr; i++) {
1987                         int *count = entry->possible_new_dirs.items[i].util;
1988
1989                         if (*count == max)
1990                                 bad_max = max;
1991                         else if (*count > max) {
1992                                 max = *count;
1993                                 best = entry->possible_new_dirs.items[i].string;
1994                         }
1995                 }
1996                 if (bad_max == max)
1997                         entry->non_unique_new_dir = 1;
1998                 else {
1999                         assert(entry->new_dir.len == 0);
2000                         strbuf_addstr(&entry->new_dir, best);
2001                 }
2002                 /*
2003                  * The relevant directory sub-portion of the original full
2004                  * filepaths were xstrndup'ed before inserting into
2005                  * possible_new_dirs, and instead of manually iterating the
2006                  * list and free'ing each, just lie and tell
2007                  * possible_new_dirs that it did the strdup'ing so that it
2008                  * will free them for us.
2009                  */
2010                 entry->possible_new_dirs.strdup_strings = 1;
2011                 string_list_clear(&entry->possible_new_dirs, 1);
2012         }
2013
2014         return dir_renames;
2015 }
2016
2017 static struct dir_rename_entry *check_dir_renamed(const char *path,
2018                                                   struct hashmap *dir_renames)
2019 {
2020         char temp[PATH_MAX];
2021         char *end;
2022         struct dir_rename_entry *entry;
2023
2024         strcpy(temp, path);
2025         while ((end = strrchr(temp, '/'))) {
2026                 *end = '\0';
2027                 entry = dir_rename_find_entry(dir_renames, temp);
2028                 if (entry)
2029                         return entry;
2030         }
2031         return NULL;
2032 }
2033
2034 static void compute_collisions(struct hashmap *collisions,
2035                                struct hashmap *dir_renames,
2036                                struct diff_queue_struct *pairs)
2037 {
2038         int i;
2039
2040         /*
2041          * Multiple files can be mapped to the same path due to directory
2042          * renames done by the other side of history.  Since that other
2043          * side of history could have merged multiple directories into one,
2044          * if our side of history added the same file basename to each of
2045          * those directories, then all N of them would get implicitly
2046          * renamed by the directory rename detection into the same path,
2047          * and we'd get an add/add/.../add conflict, and all those adds
2048          * from *this* side of history.  This is not representable in the
2049          * index, and users aren't going to easily be able to make sense of
2050          * it.  So we need to provide a good warning about what's
2051          * happening, and fall back to no-directory-rename detection
2052          * behavior for those paths.
2053          *
2054          * See testcases 9e and all of section 5 from t6043 for examples.
2055          */
2056         collision_init(collisions);
2057
2058         for (i = 0; i < pairs->nr; ++i) {
2059                 struct dir_rename_entry *dir_rename_ent;
2060                 struct collision_entry *collision_ent;
2061                 char *new_path;
2062                 struct diff_filepair *pair = pairs->queue[i];
2063
2064                 if (pair->status != 'A' && pair->status != 'R')
2065                         continue;
2066                 dir_rename_ent = check_dir_renamed(pair->two->path,
2067                                                    dir_renames);
2068                 if (!dir_rename_ent)
2069                         continue;
2070
2071                 new_path = apply_dir_rename(dir_rename_ent, pair->two->path);
2072                 if (!new_path)
2073                         /*
2074                          * dir_rename_ent->non_unique_new_path is true, which
2075                          * means there is no directory rename for us to use,
2076                          * which means it won't cause us any additional
2077                          * collisions.
2078                          */
2079                         continue;
2080                 collision_ent = collision_find_entry(collisions, new_path);
2081                 if (!collision_ent) {
2082                         collision_ent = xcalloc(1,
2083                                                 sizeof(struct collision_entry));
2084                         hashmap_entry_init(collision_ent, strhash(new_path));
2085                         hashmap_put(collisions, collision_ent);
2086                         collision_ent->target_file = new_path;
2087                 } else {
2088                         free(new_path);
2089                 }
2090                 string_list_insert(&collision_ent->source_files,
2091                                    pair->two->path);
2092         }
2093 }
2094
2095 static char *check_for_directory_rename(struct merge_options *o,
2096                                         const char *path,
2097                                         struct tree *tree,
2098                                         struct hashmap *dir_renames,
2099                                         struct hashmap *dir_rename_exclusions,
2100                                         struct hashmap *collisions,
2101                                         int *clean_merge)
2102 {
2103         char *new_path = NULL;
2104         struct dir_rename_entry *entry = check_dir_renamed(path, dir_renames);
2105         struct dir_rename_entry *oentry = NULL;
2106
2107         if (!entry)
2108                 return new_path;
2109
2110         /*
2111          * This next part is a little weird.  We do not want to do an
2112          * implicit rename into a directory we renamed on our side, because
2113          * that will result in a spurious rename/rename(1to2) conflict.  An
2114          * example:
2115          *   Base commit: dumbdir/afile, otherdir/bfile
2116          *   Side 1:      smrtdir/afile, otherdir/bfile
2117          *   Side 2:      dumbdir/afile, dumbdir/bfile
2118          * Here, while working on Side 1, we could notice that otherdir was
2119          * renamed/merged to dumbdir, and change the diff_filepair for
2120          * otherdir/bfile into a rename into dumbdir/bfile.  However, Side
2121          * 2 will notice the rename from dumbdir to smrtdir, and do the
2122          * transitive rename to move it from dumbdir/bfile to
2123          * smrtdir/bfile.  That gives us bfile in dumbdir vs being in
2124          * smrtdir, a rename/rename(1to2) conflict.  We really just want
2125          * the file to end up in smrtdir.  And the way to achieve that is
2126          * to not let Side1 do the rename to dumbdir, since we know that is
2127          * the source of one of our directory renames.
2128          *
2129          * That's why oentry and dir_rename_exclusions is here.
2130          *
2131          * As it turns out, this also prevents N-way transient rename
2132          * confusion; See testcases 9c and 9d of t6043.
2133          */
2134         oentry = dir_rename_find_entry(dir_rename_exclusions, entry->new_dir.buf);
2135         if (oentry) {
2136                 output(o, 1, _("WARNING: Avoiding applying %s -> %s rename "
2137                                "to %s, because %s itself was renamed."),
2138                        entry->dir, entry->new_dir.buf, path, entry->new_dir.buf);
2139         } else {
2140                 new_path = handle_path_level_conflicts(o, path, entry,
2141                                                        collisions, tree);
2142                 *clean_merge &= (new_path != NULL);
2143         }
2144
2145         return new_path;
2146 }
2147
2148 static void apply_directory_rename_modifications(struct merge_options *o,
2149                                                  struct diff_filepair *pair,
2150                                                  char *new_path,
2151                                                  struct rename *re,
2152                                                  struct tree *tree,
2153                                                  struct tree *o_tree,
2154                                                  struct tree *a_tree,
2155                                                  struct tree *b_tree,
2156                                                  struct string_list *entries,
2157                                                  int *clean)
2158 {
2159         struct string_list_item *item;
2160         int stage = (tree == a_tree ? 2 : 3);
2161         int update_wd;
2162
2163         /*
2164          * In all cases where we can do directory rename detection,
2165          * unpack_trees() will have read pair->two->path into the
2166          * index and the working copy.  We need to remove it so that
2167          * we can instead place it at new_path.  It is guaranteed to
2168          * not be untracked (unpack_trees() would have errored out
2169          * saying the file would have been overwritten), but it might
2170          * be dirty, though.
2171          */
2172         update_wd = !was_dirty(o, pair->two->path);
2173         if (!update_wd)
2174                 output(o, 1, _("Refusing to lose dirty file at %s"),
2175                        pair->two->path);
2176         remove_file(o, 1, pair->two->path, !update_wd);
2177
2178         /* Find or create a new re->dst_entry */
2179         item = string_list_lookup(entries, new_path);
2180         if (item) {
2181                 /*
2182                  * Since we're renaming on this side of history, and it's
2183                  * due to a directory rename on the other side of history
2184                  * (which we only allow when the directory in question no
2185                  * longer exists on the other side of history), the
2186                  * original entry for re->dst_entry is no longer
2187                  * necessary...
2188                  */
2189                 re->dst_entry->processed = 1;
2190
2191                 /*
2192                  * ...because we'll be using this new one.
2193                  */
2194                 re->dst_entry = item->util;
2195         } else {
2196                 /*
2197                  * re->dst_entry is for the before-dir-rename path, and we
2198                  * need it to hold information for the after-dir-rename
2199                  * path.  Before creating a new entry, we need to mark the
2200                  * old one as unnecessary (...unless it is shared by
2201                  * src_entry, i.e. this didn't use to be a rename, in which
2202                  * case we can just allow the normal processing to happen
2203                  * for it).
2204                  */
2205                 if (pair->status == 'R')
2206                         re->dst_entry->processed = 1;
2207
2208                 re->dst_entry = insert_stage_data(new_path,
2209                                                   o_tree, a_tree, b_tree,
2210                                                   entries);
2211                 item = string_list_insert(entries, new_path);
2212                 item->util = re->dst_entry;
2213         }
2214
2215         /*
2216          * Update the stage_data with the information about the path we are
2217          * moving into place.  That slot will be empty and available for us
2218          * to write to because of the collision checks in
2219          * handle_path_level_conflicts().  In other words,
2220          * re->dst_entry->stages[stage].oid will be the null_oid, so it's
2221          * open for us to write to.
2222          *
2223          * It may be tempting to actually update the index at this point as
2224          * well, using update_stages_for_stage_data(), but as per the big
2225          * "NOTE" in update_stages(), doing so will modify the current
2226          * in-memory index which will break calls to would_lose_untracked()
2227          * that we need to make.  Instead, we need to just make sure that
2228          * the various conflict_rename_*() functions update the index
2229          * explicitly rather than relying on unpack_trees() to have done it.
2230          */
2231         get_tree_entry(&tree->object.oid,
2232                        pair->two->path,
2233                        &re->dst_entry->stages[stage].oid,
2234                        &re->dst_entry->stages[stage].mode);
2235
2236         /* Update pair status */
2237         if (pair->status == 'A') {
2238                 /*
2239                  * Recording rename information for this add makes it look
2240                  * like a rename/delete conflict.  Make sure we can
2241                  * correctly handle this as an add that was moved to a new
2242                  * directory instead of reporting a rename/delete conflict.
2243                  */
2244                 re->add_turned_into_rename = 1;
2245         }
2246         /*
2247          * We don't actually look at pair->status again, but it seems
2248          * pedagogically correct to adjust it.
2249          */
2250         pair->status = 'R';
2251
2252         /*
2253          * Finally, record the new location.
2254          */
2255         pair->two->path = new_path;
2256 }
2257
2258 /*
2259  * Get information of all renames which occurred in 'pairs', making use of
2260  * any implicit directory renames inferred from the other side of history.
2261  * We need the three trees in the merge ('o_tree', 'a_tree' and 'b_tree')
2262  * to be able to associate the correct cache entries with the rename
2263  * information; tree is always equal to either a_tree or b_tree.
2264  */
2265 static struct string_list *get_renames(struct merge_options *o,
2266                                        struct diff_queue_struct *pairs,
2267                                        struct hashmap *dir_renames,
2268                                        struct hashmap *dir_rename_exclusions,
2269                                        struct tree *tree,
2270                                        struct tree *o_tree,
2271                                        struct tree *a_tree,
2272                                        struct tree *b_tree,
2273                                        struct string_list *entries,
2274                                        int *clean_merge)
2275 {
2276         int i;
2277         struct hashmap collisions;
2278         struct hashmap_iter iter;
2279         struct collision_entry *e;
2280         struct string_list *renames;
2281
2282         compute_collisions(&collisions, dir_renames, pairs);
2283         renames = xcalloc(1, sizeof(struct string_list));
2284
2285         for (i = 0; i < pairs->nr; ++i) {
2286                 struct string_list_item *item;
2287                 struct rename *re;
2288                 struct diff_filepair *pair = pairs->queue[i];
2289                 char *new_path; /* non-NULL only with directory renames */
2290
2291                 if (pair->status != 'A' && pair->status != 'R') {
2292                         diff_free_filepair(pair);
2293                         continue;
2294                 }
2295                 new_path = check_for_directory_rename(o, pair->two->path, tree,
2296                                                       dir_renames,
2297                                                       dir_rename_exclusions,
2298                                                       &collisions,
2299                                                       clean_merge);
2300                 if (pair->status != 'R' && !new_path) {
2301                         diff_free_filepair(pair);
2302                         continue;
2303                 }
2304
2305                 re = xmalloc(sizeof(*re));
2306                 re->processed = 0;
2307                 re->add_turned_into_rename = 0;
2308                 re->pair = pair;
2309                 item = string_list_lookup(entries, re->pair->one->path);
2310                 if (!item)
2311                         re->src_entry = insert_stage_data(re->pair->one->path,
2312                                         o_tree, a_tree, b_tree, entries);
2313                 else
2314                         re->src_entry = item->util;
2315
2316                 item = string_list_lookup(entries, re->pair->two->path);
2317                 if (!item)
2318                         re->dst_entry = insert_stage_data(re->pair->two->path,
2319                                         o_tree, a_tree, b_tree, entries);
2320                 else
2321                         re->dst_entry = item->util;
2322                 item = string_list_insert(renames, pair->one->path);
2323                 item->util = re;
2324                 if (new_path)
2325                         apply_directory_rename_modifications(o, pair, new_path,
2326                                                              re, tree, o_tree,
2327                                                              a_tree, b_tree,
2328                                                              entries,
2329                                                              clean_merge);
2330         }
2331
2332         hashmap_iter_init(&collisions, &iter);
2333         while ((e = hashmap_iter_next(&iter))) {
2334                 free(e->target_file);
2335                 string_list_clear(&e->source_files, 0);
2336         }
2337         hashmap_free(&collisions, 1);
2338         return renames;
2339 }
2340
2341 static int process_renames(struct merge_options *o,
2342                            struct string_list *a_renames,
2343                            struct string_list *b_renames)
2344 {
2345         int clean_merge = 1, i, j;
2346         struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
2347         struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
2348         const struct rename *sre;
2349
2350         for (i = 0; i < a_renames->nr; i++) {
2351                 sre = a_renames->items[i].util;
2352                 string_list_insert(&a_by_dst, sre->pair->two->path)->util
2353                         = (void *)sre;
2354         }
2355         for (i = 0; i < b_renames->nr; i++) {
2356                 sre = b_renames->items[i].util;
2357                 string_list_insert(&b_by_dst, sre->pair->two->path)->util
2358                         = (void *)sre;
2359         }
2360
2361         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
2362                 struct string_list *renames1, *renames2Dst;
2363                 struct rename *ren1 = NULL, *ren2 = NULL;
2364                 const char *branch1, *branch2;
2365                 const char *ren1_src, *ren1_dst;
2366                 struct string_list_item *lookup;
2367
2368                 if (i >= a_renames->nr) {
2369                         ren2 = b_renames->items[j++].util;
2370                 } else if (j >= b_renames->nr) {
2371                         ren1 = a_renames->items[i++].util;
2372                 } else {
2373                         int compare = strcmp(a_renames->items[i].string,
2374                                              b_renames->items[j].string);
2375                         if (compare <= 0)
2376                                 ren1 = a_renames->items[i++].util;
2377                         if (compare >= 0)
2378                                 ren2 = b_renames->items[j++].util;
2379                 }
2380
2381                 /* TODO: refactor, so that 1/2 are not needed */
2382                 if (ren1) {
2383                         renames1 = a_renames;
2384                         renames2Dst = &b_by_dst;
2385                         branch1 = o->branch1;
2386                         branch2 = o->branch2;
2387                 } else {
2388                         renames1 = b_renames;
2389                         renames2Dst = &a_by_dst;
2390                         branch1 = o->branch2;
2391                         branch2 = o->branch1;
2392                         SWAP(ren2, ren1);
2393                 }
2394
2395                 if (ren1->processed)
2396                         continue;
2397                 ren1->processed = 1;
2398                 ren1->dst_entry->processed = 1;
2399                 /* BUG: We should only mark src_entry as processed if we
2400                  * are not dealing with a rename + add-source case.
2401                  */
2402                 ren1->src_entry->processed = 1;
2403
2404                 ren1_src = ren1->pair->one->path;
2405                 ren1_dst = ren1->pair->two->path;
2406
2407                 if (ren2) {
2408                         /* One file renamed on both sides */
2409                         const char *ren2_src = ren2->pair->one->path;
2410                         const char *ren2_dst = ren2->pair->two->path;
2411                         enum rename_type rename_type;
2412                         if (strcmp(ren1_src, ren2_src) != 0)
2413                                 die("BUG: ren1_src != ren2_src");
2414                         ren2->dst_entry->processed = 1;
2415                         ren2->processed = 1;
2416                         if (strcmp(ren1_dst, ren2_dst) != 0) {
2417                                 rename_type = RENAME_ONE_FILE_TO_TWO;
2418                                 clean_merge = 0;
2419                         } else {
2420                                 rename_type = RENAME_ONE_FILE_TO_ONE;
2421                                 /* BUG: We should only remove ren1_src in
2422                                  * the base stage (think of rename +
2423                                  * add-source cases).
2424                                  */
2425                                 remove_file(o, 1, ren1_src, 1);
2426                                 update_entry(ren1->dst_entry,
2427                                              ren1->pair->one,
2428                                              ren1->pair->two,
2429                                              ren2->pair->two);
2430                         }
2431                         setup_rename_conflict_info(rename_type,
2432                                                    ren1->pair,
2433                                                    ren2->pair,
2434                                                    branch1,
2435                                                    branch2,
2436                                                    ren1->dst_entry,
2437                                                    ren2->dst_entry,
2438                                                    o,
2439                                                    NULL,
2440                                                    NULL);
2441                 } else if ((lookup = string_list_lookup(renames2Dst, ren1_dst))) {
2442                         /* Two different files renamed to the same thing */
2443                         char *ren2_dst;
2444                         ren2 = lookup->util;
2445                         ren2_dst = ren2->pair->two->path;
2446                         if (strcmp(ren1_dst, ren2_dst) != 0)
2447                                 die("BUG: ren1_dst != ren2_dst");
2448
2449                         clean_merge = 0;
2450                         ren2->processed = 1;
2451                         /*
2452                          * BUG: We should only mark src_entry as processed
2453                          * if we are not dealing with a rename + add-source
2454                          * case.
2455                          */
2456                         ren2->src_entry->processed = 1;
2457
2458                         setup_rename_conflict_info(RENAME_TWO_FILES_TO_ONE,
2459                                                    ren1->pair,
2460                                                    ren2->pair,
2461                                                    branch1,
2462                                                    branch2,
2463                                                    ren1->dst_entry,
2464                                                    ren2->dst_entry,
2465                                                    o,
2466                                                    ren1->src_entry,
2467                                                    ren2->src_entry);
2468
2469                 } else {
2470                         /* Renamed in 1, maybe changed in 2 */
2471                         /* we only use sha1 and mode of these */
2472                         struct diff_filespec src_other, dst_other;
2473                         int try_merge;
2474
2475                         /*
2476                          * unpack_trees loads entries from common-commit
2477                          * into stage 1, from head-commit into stage 2, and
2478                          * from merge-commit into stage 3.  We keep track
2479                          * of which side corresponds to the rename.
2480                          */
2481                         int renamed_stage = a_renames == renames1 ? 2 : 3;
2482                         int other_stage =   a_renames == renames1 ? 3 : 2;
2483
2484                         /* BUG: We should only remove ren1_src in the base
2485                          * stage and in other_stage (think of rename +
2486                          * add-source case).
2487                          */
2488                         remove_file(o, 1, ren1_src,
2489                                     renamed_stage == 2 || !was_tracked(o, ren1_src));
2490
2491                         oidcpy(&src_other.oid,
2492                                &ren1->src_entry->stages[other_stage].oid);
2493                         src_other.mode = ren1->src_entry->stages[other_stage].mode;
2494                         oidcpy(&dst_other.oid,
2495                                &ren1->dst_entry->stages[other_stage].oid);
2496                         dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
2497                         try_merge = 0;
2498
2499                         if (oid_eq(&src_other.oid, &null_oid) &&
2500                             ren1->add_turned_into_rename) {
2501                                 setup_rename_conflict_info(RENAME_DIR,
2502                                                            ren1->pair,
2503                                                            NULL,
2504                                                            branch1,
2505                                                            branch2,
2506                                                            ren1->dst_entry,
2507                                                            NULL,
2508                                                            o,
2509                                                            NULL,
2510                                                            NULL);
2511                         } else if (oid_eq(&src_other.oid, &null_oid)) {
2512                                 setup_rename_conflict_info(RENAME_DELETE,
2513                                                            ren1->pair,
2514                                                            NULL,
2515                                                            branch1,
2516                                                            branch2,
2517                                                            ren1->dst_entry,
2518                                                            NULL,
2519                                                            o,
2520                                                            NULL,
2521                                                            NULL);
2522                         } else if ((dst_other.mode == ren1->pair->two->mode) &&
2523                                    oid_eq(&dst_other.oid, &ren1->pair->two->oid)) {
2524                                 /*
2525                                  * Added file on the other side identical to
2526                                  * the file being renamed: clean merge.
2527                                  * Also, there is no need to overwrite the
2528                                  * file already in the working copy, so call
2529                                  * update_file_flags() instead of
2530                                  * update_file().
2531                                  */
2532                                 if (update_file_flags(o,
2533                                                       &ren1->pair->two->oid,
2534                                                       ren1->pair->two->mode,
2535                                                       ren1_dst,
2536                                                       1, /* update_cache */
2537                                                       0  /* update_wd    */))
2538                                         clean_merge = -1;
2539                         } else if (!oid_eq(&dst_other.oid, &null_oid)) {
2540                                 clean_merge = 0;
2541                                 try_merge = 1;
2542                                 output(o, 1, _("CONFLICT (rename/add): Rename %s->%s in %s. "
2543                                        "%s added in %s"),
2544                                        ren1_src, ren1_dst, branch1,
2545                                        ren1_dst, branch2);
2546                                 if (o->call_depth) {
2547                                         struct merge_file_info mfi;
2548                                         if (merge_file_one(o, ren1_dst, &null_oid, 0,
2549                                                            &ren1->pair->two->oid,
2550                                                            ren1->pair->two->mode,
2551                                                            &dst_other.oid,
2552                                                            dst_other.mode,
2553                                                            branch1, branch2, &mfi)) {
2554                                                 clean_merge = -1;
2555                                                 goto cleanup_and_return;
2556                                         }
2557                                         output(o, 1, _("Adding merged %s"), ren1_dst);
2558                                         if (update_file(o, 0, &mfi.oid,
2559                                                         mfi.mode, ren1_dst))
2560                                                 clean_merge = -1;
2561                                         try_merge = 0;
2562                                 } else {
2563                                         char *new_path = unique_path(o, ren1_dst, branch2);
2564                                         output(o, 1, _("Adding as %s instead"), new_path);
2565                                         if (update_file(o, 0, &dst_other.oid,
2566                                                         dst_other.mode, new_path))
2567                                                 clean_merge = -1;
2568                                         free(new_path);
2569                                 }
2570                         } else
2571                                 try_merge = 1;
2572
2573                         if (clean_merge < 0)
2574                                 goto cleanup_and_return;
2575                         if (try_merge) {
2576                                 struct diff_filespec *one, *a, *b;
2577                                 src_other.path = (char *)ren1_src;
2578
2579                                 one = ren1->pair->one;
2580                                 if (a_renames == renames1) {
2581                                         a = ren1->pair->two;
2582                                         b = &src_other;
2583                                 } else {
2584                                         b = ren1->pair->two;
2585                                         a = &src_other;
2586                                 }
2587                                 update_entry(ren1->dst_entry, one, a, b);
2588                                 setup_rename_conflict_info(RENAME_NORMAL,
2589                                                            ren1->pair,
2590                                                            NULL,
2591                                                            branch1,
2592                                                            NULL,
2593                                                            ren1->dst_entry,
2594                                                            NULL,
2595                                                            o,
2596                                                            NULL,
2597                                                            NULL);
2598                         }
2599                 }
2600         }
2601 cleanup_and_return:
2602         string_list_clear(&a_by_dst, 0);
2603         string_list_clear(&b_by_dst, 0);
2604
2605         return clean_merge;
2606 }
2607
2608 struct rename_info {
2609         struct string_list *head_renames;
2610         struct string_list *merge_renames;
2611 };
2612
2613 static void initial_cleanup_rename(struct diff_queue_struct *pairs,
2614                                    struct hashmap *dir_renames)
2615 {
2616         struct hashmap_iter iter;
2617         struct dir_rename_entry *e;
2618
2619         hashmap_iter_init(dir_renames, &iter);
2620         while ((e = hashmap_iter_next(&iter))) {
2621                 free(e->dir);
2622                 strbuf_release(&e->new_dir);
2623                 /* possible_new_dirs already cleared in get_directory_renames */
2624         }
2625         hashmap_free(dir_renames, 1);
2626         free(dir_renames);
2627
2628         free(pairs->queue);
2629         free(pairs);
2630 }
2631
2632 static int handle_renames(struct merge_options *o,
2633                           struct tree *common,
2634                           struct tree *head,
2635                           struct tree *merge,
2636                           struct string_list *entries,
2637                           struct rename_info *ri)
2638 {
2639         struct diff_queue_struct *head_pairs, *merge_pairs;
2640         struct hashmap *dir_re_head, *dir_re_merge;
2641         int clean = 1;
2642
2643         ri->head_renames = NULL;
2644         ri->merge_renames = NULL;
2645
2646         if (!o->detect_rename)
2647                 return 1;
2648
2649         head_pairs = get_diffpairs(o, common, head);
2650         merge_pairs = get_diffpairs(o, common, merge);
2651
2652         dir_re_head = get_directory_renames(head_pairs, head);
2653         dir_re_merge = get_directory_renames(merge_pairs, merge);
2654
2655         handle_directory_level_conflicts(o,
2656                                          dir_re_head, head,
2657                                          dir_re_merge, merge);
2658
2659         ri->head_renames  = get_renames(o, head_pairs,
2660                                         dir_re_merge, dir_re_head, head,
2661                                         common, head, merge, entries,
2662                                         &clean);
2663         if (clean < 0)
2664                 goto cleanup;
2665         ri->merge_renames = get_renames(o, merge_pairs,
2666                                         dir_re_head, dir_re_merge, merge,
2667                                         common, head, merge, entries,
2668                                         &clean);
2669         if (clean < 0)
2670                 goto cleanup;
2671         clean &= process_renames(o, ri->head_renames, ri->merge_renames);
2672
2673 cleanup:
2674         /*
2675          * Some cleanup is deferred until cleanup_renames() because the
2676          * data structures are still needed and referenced in
2677          * process_entry().  But there are a few things we can free now.
2678          */
2679         initial_cleanup_rename(head_pairs, dir_re_head);
2680         initial_cleanup_rename(merge_pairs, dir_re_merge);
2681
2682         return clean;
2683 }
2684
2685 static void final_cleanup_rename(struct string_list *rename)
2686 {
2687         const struct rename *re;
2688         int i;
2689
2690         if (rename == NULL)
2691                 return;
2692
2693         for (i = 0; i < rename->nr; i++) {
2694                 re = rename->items[i].util;
2695                 diff_free_filepair(re->pair);
2696         }
2697         string_list_clear(rename, 1);
2698         free(rename);
2699 }
2700
2701 static void final_cleanup_renames(struct rename_info *re_info)
2702 {
2703         final_cleanup_rename(re_info->head_renames);
2704         final_cleanup_rename(re_info->merge_renames);
2705 }
2706
2707 static struct object_id *stage_oid(const struct object_id *oid, unsigned mode)
2708 {
2709         return (is_null_oid(oid) || mode == 0) ? NULL: (struct object_id *)oid;
2710 }
2711
2712 static int read_oid_strbuf(struct merge_options *o,
2713         const struct object_id *oid, struct strbuf *dst)
2714 {
2715         void *buf;
2716         enum object_type type;
2717         unsigned long size;
2718         buf = read_object_file(oid, &type, &size);
2719         if (!buf)
2720                 return err(o, _("cannot read object %s"), oid_to_hex(oid));
2721         if (type != OBJ_BLOB) {
2722                 free(buf);
2723                 return err(o, _("object %s is not a blob"), oid_to_hex(oid));
2724         }
2725         strbuf_attach(dst, buf, size, size + 1);
2726         return 0;
2727 }
2728
2729 static int blob_unchanged(struct merge_options *opt,
2730                           const struct object_id *o_oid,
2731                           unsigned o_mode,
2732                           const struct object_id *a_oid,
2733                           unsigned a_mode,
2734                           int renormalize, const char *path)
2735 {
2736         struct strbuf o = STRBUF_INIT;
2737         struct strbuf a = STRBUF_INIT;
2738         int ret = 0; /* assume changed for safety */
2739
2740         if (a_mode != o_mode)
2741                 return 0;
2742         if (oid_eq(o_oid, a_oid))
2743                 return 1;
2744         if (!renormalize)
2745                 return 0;
2746
2747         assert(o_oid && a_oid);
2748         if (read_oid_strbuf(opt, o_oid, &o) || read_oid_strbuf(opt, a_oid, &a))
2749                 goto error_return;
2750         /*
2751          * Note: binary | is used so that both renormalizations are
2752          * performed.  Comparison can be skipped if both files are
2753          * unchanged since their sha1s have already been compared.
2754          */
2755         if (renormalize_buffer(&the_index, path, o.buf, o.len, &o) |
2756             renormalize_buffer(&the_index, path, a.buf, a.len, &a))
2757                 ret = (o.len == a.len && !memcmp(o.buf, a.buf, o.len));
2758
2759 error_return:
2760         strbuf_release(&o);
2761         strbuf_release(&a);
2762         return ret;
2763 }
2764
2765 static int handle_modify_delete(struct merge_options *o,
2766                                  const char *path,
2767                                  struct object_id *o_oid, int o_mode,
2768                                  struct object_id *a_oid, int a_mode,
2769                                  struct object_id *b_oid, int b_mode)
2770 {
2771         const char *modify_branch, *delete_branch;
2772         struct object_id *changed_oid;
2773         int changed_mode;
2774
2775         if (a_oid) {
2776                 modify_branch = o->branch1;
2777                 delete_branch = o->branch2;
2778                 changed_oid = a_oid;
2779                 changed_mode = a_mode;
2780         } else {
2781                 modify_branch = o->branch2;
2782                 delete_branch = o->branch1;
2783                 changed_oid = b_oid;
2784                 changed_mode = b_mode;
2785         }
2786
2787         return handle_change_delete(o,
2788                                     path, NULL,
2789                                     o_oid, o_mode,
2790                                     changed_oid, changed_mode,
2791                                     modify_branch, delete_branch,
2792                                     _("modify"), _("modified"));
2793 }
2794
2795 static int merge_content(struct merge_options *o,
2796                          const char *path,
2797                          int is_dirty,
2798                          struct object_id *o_oid, int o_mode,
2799                          struct object_id *a_oid, int a_mode,
2800                          struct object_id *b_oid, int b_mode,
2801                          struct rename_conflict_info *rename_conflict_info)
2802 {
2803         const char *reason = _("content");
2804         const char *path1 = NULL, *path2 = NULL;
2805         struct merge_file_info mfi;
2806         struct diff_filespec one, a, b;
2807         unsigned df_conflict_remains = 0;
2808
2809         if (!o_oid) {
2810                 reason = _("add/add");
2811                 o_oid = (struct object_id *)&null_oid;
2812         }
2813         one.path = a.path = b.path = (char *)path;
2814         oidcpy(&one.oid, o_oid);
2815         one.mode = o_mode;
2816         oidcpy(&a.oid, a_oid);
2817         a.mode = a_mode;
2818         oidcpy(&b.oid, b_oid);
2819         b.mode = b_mode;
2820
2821         if (rename_conflict_info) {
2822                 struct diff_filepair *pair1 = rename_conflict_info->pair1;
2823
2824                 path1 = (o->branch1 == rename_conflict_info->branch1) ?
2825                         pair1->two->path : pair1->one->path;
2826                 /* If rename_conflict_info->pair2 != NULL, we are in
2827                  * RENAME_ONE_FILE_TO_ONE case.  Otherwise, we have a
2828                  * normal rename.
2829                  */
2830                 path2 = (rename_conflict_info->pair2 ||
2831                          o->branch2 == rename_conflict_info->branch1) ?
2832                         pair1->two->path : pair1->one->path;
2833
2834                 if (dir_in_way(path, !o->call_depth,
2835                                S_ISGITLINK(pair1->two->mode)))
2836                         df_conflict_remains = 1;
2837         }
2838         if (merge_file_special_markers(o, &one, &a, &b, path,
2839                                        o->branch1, path1,
2840                                        o->branch2, path2, &mfi))
2841                 return -1;
2842
2843         /*
2844          * We can skip updating the working tree file iff:
2845          *   a) The merge is clean
2846          *   b) The merge matches what was in HEAD (content, mode, pathname)
2847          *   c) The target path is usable (i.e. not involved in D/F conflict)
2848          */
2849         if (mfi.clean &&
2850             was_tracked_and_matches(o, path, &mfi.oid, mfi.mode) &&
2851             !df_conflict_remains) {
2852                 output(o, 3, _("Skipped %s (merged same as existing)"), path);
2853                 if (add_cacheinfo(o, mfi.mode, &mfi.oid, path,
2854                                   0, (!o->call_depth && !is_dirty), 0))
2855                         return -1;
2856                 return mfi.clean;
2857         }
2858
2859         if (!mfi.clean) {
2860                 if (S_ISGITLINK(mfi.mode))
2861                         reason = _("submodule");
2862                 output(o, 1, _("CONFLICT (%s): Merge conflict in %s"),
2863                                 reason, path);
2864                 if (rename_conflict_info && !df_conflict_remains)
2865                         if (update_stages(o, path, &one, &a, &b))
2866                                 return -1;
2867         }
2868
2869         if (df_conflict_remains || is_dirty) {
2870                 char *new_path;
2871                 if (o->call_depth) {
2872                         remove_file_from_cache(path);
2873                 } else {
2874                         if (!mfi.clean) {
2875                                 if (update_stages(o, path, &one, &a, &b))
2876                                         return -1;
2877                         } else {
2878                                 int file_from_stage2 = was_tracked(o, path);
2879                                 struct diff_filespec merged;
2880                                 oidcpy(&merged.oid, &mfi.oid);
2881                                 merged.mode = mfi.mode;
2882
2883                                 if (update_stages(o, path, NULL,
2884                                                   file_from_stage2 ? &merged : NULL,
2885                                                   file_from_stage2 ? NULL : &merged))
2886                                         return -1;
2887                         }
2888
2889                 }
2890                 new_path = unique_path(o, path, rename_conflict_info->branch1);
2891                 if (is_dirty) {
2892                         output(o, 1, _("Refusing to lose dirty file at %s"),
2893                                path);
2894                 }
2895                 output(o, 1, _("Adding as %s instead"), new_path);
2896                 if (update_file(o, 0, &mfi.oid, mfi.mode, new_path)) {
2897                         free(new_path);
2898                         return -1;
2899                 }
2900                 free(new_path);
2901                 mfi.clean = 0;
2902         } else if (update_file(o, mfi.clean, &mfi.oid, mfi.mode, path))
2903                 return -1;
2904         return !is_dirty && mfi.clean;
2905 }
2906
2907 static int conflict_rename_normal(struct merge_options *o,
2908                                   const char *path,
2909                                   struct object_id *o_oid, unsigned int o_mode,
2910                                   struct object_id *a_oid, unsigned int a_mode,
2911                                   struct object_id *b_oid, unsigned int b_mode,
2912                                   struct rename_conflict_info *ci)
2913 {
2914         /* Merge the content and write it out */
2915         return merge_content(o, path, was_dirty(o, path),
2916                              o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
2917                              ci);
2918 }
2919
2920 /* Per entry merge function */
2921 static int process_entry(struct merge_options *o,
2922                          const char *path, struct stage_data *entry)
2923 {
2924         int clean_merge = 1;
2925         int normalize = o->renormalize;
2926         unsigned o_mode = entry->stages[1].mode;
2927         unsigned a_mode = entry->stages[2].mode;
2928         unsigned b_mode = entry->stages[3].mode;
2929         struct object_id *o_oid = stage_oid(&entry->stages[1].oid, o_mode);
2930         struct object_id *a_oid = stage_oid(&entry->stages[2].oid, a_mode);
2931         struct object_id *b_oid = stage_oid(&entry->stages[3].oid, b_mode);
2932
2933         entry->processed = 1;
2934         if (entry->rename_conflict_info) {
2935                 struct rename_conflict_info *conflict_info = entry->rename_conflict_info;
2936                 switch (conflict_info->rename_type) {
2937                 case RENAME_NORMAL:
2938                 case RENAME_ONE_FILE_TO_ONE:
2939                         clean_merge = conflict_rename_normal(o,
2940                                                              path,
2941                                                              o_oid, o_mode,
2942                                                              a_oid, a_mode,
2943                                                              b_oid, b_mode,
2944                                                              conflict_info);
2945                         break;
2946                 case RENAME_DIR:
2947                         clean_merge = 1;
2948                         if (conflict_rename_dir(o,
2949                                                 conflict_info->pair1,
2950                                                 conflict_info->branch1,
2951                                                 conflict_info->branch2))
2952                                 clean_merge = -1;
2953                         break;
2954                 case RENAME_DELETE:
2955                         clean_merge = 0;
2956                         if (conflict_rename_delete(o,
2957                                                    conflict_info->pair1,
2958                                                    conflict_info->branch1,
2959                                                    conflict_info->branch2))
2960                                 clean_merge = -1;
2961                         break;
2962                 case RENAME_ONE_FILE_TO_TWO:
2963                         clean_merge = 0;
2964                         if (conflict_rename_rename_1to2(o, conflict_info))
2965                                 clean_merge = -1;
2966                         break;
2967                 case RENAME_TWO_FILES_TO_ONE:
2968                         clean_merge = 0;
2969                         if (conflict_rename_rename_2to1(o, conflict_info))
2970                                 clean_merge = -1;
2971                         break;
2972                 default:
2973                         entry->processed = 0;
2974                         break;
2975                 }
2976         } else if (o_oid && (!a_oid || !b_oid)) {
2977                 /* Case A: Deleted in one */
2978                 if ((!a_oid && !b_oid) ||
2979                     (!b_oid && blob_unchanged(o, o_oid, o_mode, a_oid, a_mode, normalize, path)) ||
2980                     (!a_oid && blob_unchanged(o, o_oid, o_mode, b_oid, b_mode, normalize, path))) {
2981                         /* Deleted in both or deleted in one and
2982                          * unchanged in the other */
2983                         if (a_oid)
2984                                 output(o, 2, _("Removing %s"), path);
2985                         /* do not touch working file if it did not exist */
2986                         remove_file(o, 1, path, !a_oid);
2987                 } else {
2988                         /* Modify/delete; deleted side may have put a directory in the way */
2989                         clean_merge = 0;
2990                         if (handle_modify_delete(o, path, o_oid, o_mode,
2991                                                  a_oid, a_mode, b_oid, b_mode))
2992                                 clean_merge = -1;
2993                 }
2994         } else if ((!o_oid && a_oid && !b_oid) ||
2995                    (!o_oid && !a_oid && b_oid)) {
2996                 /* Case B: Added in one. */
2997                 /* [nothing|directory] -> ([nothing|directory], file) */
2998
2999                 const char *add_branch;
3000                 const char *other_branch;
3001                 unsigned mode;
3002                 const struct object_id *oid;
3003                 const char *conf;
3004
3005                 if (a_oid) {
3006                         add_branch = o->branch1;
3007                         other_branch = o->branch2;
3008                         mode = a_mode;
3009                         oid = a_oid;
3010                         conf = _("file/directory");
3011                 } else {
3012                         add_branch = o->branch2;
3013                         other_branch = o->branch1;
3014                         mode = b_mode;
3015                         oid = b_oid;
3016                         conf = _("directory/file");
3017                 }
3018                 if (dir_in_way(path,
3019                                !o->call_depth && !S_ISGITLINK(a_mode),
3020                                0)) {
3021                         char *new_path = unique_path(o, path, add_branch);
3022                         clean_merge = 0;
3023                         output(o, 1, _("CONFLICT (%s): There is a directory with name %s in %s. "
3024                                "Adding %s as %s"),
3025                                conf, path, other_branch, path, new_path);
3026                         if (update_file(o, 0, oid, mode, new_path))
3027                                 clean_merge = -1;
3028                         else if (o->call_depth)
3029                                 remove_file_from_cache(path);
3030                         free(new_path);
3031                 } else {
3032                         output(o, 2, _("Adding %s"), path);
3033                         /* do not overwrite file if already present */
3034                         if (update_file_flags(o, oid, mode, path, 1, !a_oid))
3035                                 clean_merge = -1;
3036                 }
3037         } else if (a_oid && b_oid) {
3038                 /* Case C: Added in both (check for same permissions) and */
3039                 /* case D: Modified in both, but differently. */
3040                 int is_dirty = 0; /* unpack_trees would have bailed if dirty */
3041                 clean_merge = merge_content(o, path, is_dirty,
3042                                             o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
3043                                             NULL);
3044         } else if (!o_oid && !a_oid && !b_oid) {
3045                 /*
3046                  * this entry was deleted altogether. a_mode == 0 means
3047                  * we had that path and want to actively remove it.
3048                  */
3049                 remove_file(o, 1, path, !a_mode);
3050         } else
3051                 die("BUG: fatal merge failure, shouldn't happen.");
3052
3053         return clean_merge;
3054 }
3055
3056 int merge_trees(struct merge_options *o,
3057                 struct tree *head,
3058                 struct tree *merge,
3059                 struct tree *common,
3060                 struct tree **result)
3061 {
3062         int code, clean;
3063
3064         if (o->subtree_shift) {
3065                 merge = shift_tree_object(head, merge, o->subtree_shift);
3066                 common = shift_tree_object(head, common, o->subtree_shift);
3067         }
3068
3069         if (oid_eq(&common->object.oid, &merge->object.oid)) {
3070                 struct strbuf sb = STRBUF_INIT;
3071
3072                 if (!o->call_depth && index_has_changes(&sb)) {
3073                         err(o, _("Dirty index: cannot merge (dirty: %s)"),
3074                             sb.buf);
3075                         return 0;
3076                 }
3077                 output(o, 0, _("Already up to date!"));
3078                 *result = head;
3079                 return 1;
3080         }
3081
3082         code = git_merge_trees(o, common, head, merge);
3083
3084         if (code != 0) {
3085                 if (show(o, 4) || o->call_depth)
3086                         err(o, _("merging of trees %s and %s failed"),
3087                             oid_to_hex(&head->object.oid),
3088                             oid_to_hex(&merge->object.oid));
3089                 return -1;
3090         }
3091
3092         if (unmerged_cache()) {
3093                 struct string_list *entries;
3094                 struct rename_info re_info;
3095                 int i;
3096                 /*
3097                  * Only need the hashmap while processing entries, so
3098                  * initialize it here and free it when we are done running
3099                  * through the entries. Keeping it in the merge_options as
3100                  * opposed to decaring a local hashmap is for convenience
3101                  * so that we don't have to pass it to around.
3102                  */
3103                 hashmap_init(&o->current_file_dir_set, path_hashmap_cmp, NULL, 512);
3104                 get_files_dirs(o, head);
3105                 get_files_dirs(o, merge);
3106
3107                 entries = get_unmerged();
3108                 clean = handle_renames(o, common, head, merge, entries,
3109                                        &re_info);
3110                 record_df_conflict_files(o, entries);
3111                 if (clean < 0)
3112                         goto cleanup;
3113                 for (i = entries->nr-1; 0 <= i; i--) {
3114                         const char *path = entries->items[i].string;
3115                         struct stage_data *e = entries->items[i].util;
3116                         if (!e->processed) {
3117                                 int ret = process_entry(o, path, e);
3118                                 if (!ret)
3119                                         clean = 0;
3120                                 else if (ret < 0) {
3121                                         clean = ret;
3122                                         goto cleanup;
3123                                 }
3124                         }
3125                 }
3126                 for (i = 0; i < entries->nr; i++) {
3127                         struct stage_data *e = entries->items[i].util;
3128                         if (!e->processed)
3129                                 die("BUG: unprocessed path??? %s",
3130                                     entries->items[i].string);
3131                 }
3132
3133 cleanup:
3134                 final_cleanup_renames(&re_info);
3135
3136                 string_list_clear(entries, 1);
3137                 free(entries);
3138
3139                 hashmap_free(&o->current_file_dir_set, 1);
3140
3141                 if (clean < 0)
3142                         return clean;
3143         }
3144         else
3145                 clean = 1;
3146
3147         /* Free the extra index left from git_merge_trees() */
3148         /*
3149          * FIXME: Need to also free data allocated by
3150          * setup_unpack_trees_porcelain() tucked away in o->unpack_opts.msgs,
3151          * but the problem is that only half of it refers to dynamically
3152          * allocated data, while the other half points at static strings.
3153          */
3154         discard_index(&o->orig_index);
3155
3156         if (o->call_depth && !(*result = write_tree_from_memory(o)))
3157                 return -1;
3158
3159         return clean;
3160 }
3161
3162 static struct commit_list *reverse_commit_list(struct commit_list *list)
3163 {
3164         struct commit_list *next = NULL, *current, *backup;
3165         for (current = list; current; current = backup) {
3166                 backup = current->next;
3167                 current->next = next;
3168                 next = current;
3169         }
3170         return next;
3171 }
3172
3173 /*
3174  * Merge the commits h1 and h2, return the resulting virtual
3175  * commit object and a flag indicating the cleanness of the merge.
3176  */
3177 int merge_recursive(struct merge_options *o,
3178                     struct commit *h1,
3179                     struct commit *h2,
3180                     struct commit_list *ca,
3181                     struct commit **result)
3182 {
3183         struct commit_list *iter;
3184         struct commit *merged_common_ancestors;
3185         struct tree *mrtree;
3186         int clean;
3187
3188         if (show(o, 4)) {
3189                 output(o, 4, _("Merging:"));
3190                 output_commit_title(o, h1);
3191                 output_commit_title(o, h2);
3192         }
3193
3194         if (!ca) {
3195                 ca = get_merge_bases(h1, h2);
3196                 ca = reverse_commit_list(ca);
3197         }
3198
3199         if (show(o, 5)) {
3200                 unsigned cnt = commit_list_count(ca);
3201
3202                 output(o, 5, Q_("found %u common ancestor:",
3203                                 "found %u common ancestors:", cnt), cnt);
3204                 for (iter = ca; iter; iter = iter->next)
3205                         output_commit_title(o, iter->item);
3206         }
3207
3208         merged_common_ancestors = pop_commit(&ca);
3209         if (merged_common_ancestors == NULL) {
3210                 /* if there is no common ancestor, use an empty tree */
3211                 struct tree *tree;
3212
3213                 tree = lookup_tree(the_hash_algo->empty_tree);
3214                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
3215         }
3216
3217         for (iter = ca; iter; iter = iter->next) {
3218                 const char *saved_b1, *saved_b2;
3219                 o->call_depth++;
3220                 /*
3221                  * When the merge fails, the result contains files
3222                  * with conflict markers. The cleanness flag is
3223                  * ignored (unless indicating an error), it was never
3224                  * actually used, as result of merge_trees has always
3225                  * overwritten it: the committed "conflicts" were
3226                  * already resolved.
3227                  */
3228                 discard_cache();
3229                 saved_b1 = o->branch1;
3230                 saved_b2 = o->branch2;
3231                 o->branch1 = "Temporary merge branch 1";
3232                 o->branch2 = "Temporary merge branch 2";
3233                 if (merge_recursive(o, merged_common_ancestors, iter->item,
3234                                     NULL, &merged_common_ancestors) < 0)
3235                         return -1;
3236                 o->branch1 = saved_b1;
3237                 o->branch2 = saved_b2;
3238                 o->call_depth--;
3239
3240                 if (!merged_common_ancestors)
3241                         return err(o, _("merge returned no commit"));
3242         }
3243
3244         discard_cache();
3245         if (!o->call_depth)
3246                 read_cache();
3247
3248         o->ancestor = "merged common ancestors";
3249         clean = merge_trees(o, get_commit_tree(h1), get_commit_tree(h2),
3250                             get_commit_tree(merged_common_ancestors),
3251                             &mrtree);
3252         if (clean < 0) {
3253                 flush_output(o);
3254                 return clean;
3255         }
3256
3257         if (o->call_depth) {
3258                 *result = make_virtual_commit(mrtree, "merged tree");
3259                 commit_list_insert(h1, &(*result)->parents);
3260                 commit_list_insert(h2, &(*result)->parents->next);
3261         }
3262         flush_output(o);
3263         if (!o->call_depth && o->buffer_output < 2)
3264                 strbuf_release(&o->obuf);
3265         if (show(o, 2))
3266                 diff_warn_rename_limit("merge.renamelimit",
3267                                        o->needed_rename_limit, 0);
3268         return clean;
3269 }
3270
3271 static struct commit *get_ref(const struct object_id *oid, const char *name)
3272 {
3273         struct object *object;
3274
3275         object = deref_tag(parse_object(oid), name, strlen(name));
3276         if (!object)
3277                 return NULL;
3278         if (object->type == OBJ_TREE)
3279                 return make_virtual_commit((struct tree*)object, name);
3280         if (object->type != OBJ_COMMIT)
3281                 return NULL;
3282         if (parse_commit((struct commit *)object))
3283                 return NULL;
3284         return (struct commit *)object;
3285 }
3286
3287 int merge_recursive_generic(struct merge_options *o,
3288                             const struct object_id *head,
3289                             const struct object_id *merge,
3290                             int num_base_list,
3291                             const struct object_id **base_list,
3292                             struct commit **result)
3293 {
3294         int clean;
3295         struct lock_file lock = LOCK_INIT;
3296         struct commit *head_commit = get_ref(head, o->branch1);
3297         struct commit *next_commit = get_ref(merge, o->branch2);
3298         struct commit_list *ca = NULL;
3299
3300         if (base_list) {
3301                 int i;
3302                 for (i = 0; i < num_base_list; ++i) {
3303                         struct commit *base;
3304                         if (!(base = get_ref(base_list[i], oid_to_hex(base_list[i]))))
3305                                 return err(o, _("Could not parse object '%s'"),
3306                                         oid_to_hex(base_list[i]));
3307                         commit_list_insert(base, &ca);
3308                 }
3309         }
3310
3311         hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
3312         clean = merge_recursive(o, head_commit, next_commit, ca,
3313                         result);
3314         if (clean < 0) {
3315                 rollback_lock_file(&lock);
3316                 return clean;
3317         }
3318
3319         if (write_locked_index(&the_index, &lock,
3320                                COMMIT_LOCK | SKIP_IF_UNCHANGED))
3321                 return err(o, _("Unable to write index."));
3322
3323         return clean ? 0 : 1;
3324 }
3325
3326 static void merge_recursive_config(struct merge_options *o)
3327 {
3328         git_config_get_int("merge.verbosity", &o->verbosity);
3329         git_config_get_int("diff.renamelimit", &o->diff_rename_limit);
3330         git_config_get_int("merge.renamelimit", &o->merge_rename_limit);
3331         git_config(git_xmerge_config, NULL);
3332 }
3333
3334 void init_merge_options(struct merge_options *o)
3335 {
3336         const char *merge_verbosity;
3337         memset(o, 0, sizeof(struct merge_options));
3338         o->verbosity = 2;
3339         o->buffer_output = 1;
3340         o->diff_rename_limit = -1;
3341         o->merge_rename_limit = -1;
3342         o->renormalize = 0;
3343         o->detect_rename = 1;
3344         merge_recursive_config(o);
3345         merge_verbosity = getenv("GIT_MERGE_VERBOSITY");
3346         if (merge_verbosity)
3347                 o->verbosity = strtol(merge_verbosity, NULL, 10);
3348         if (o->verbosity >= 5)
3349                 o->buffer_output = 0;
3350         strbuf_init(&o->obuf, 0);
3351         string_list_init(&o->df_conflict_file_set, 1);
3352 }
3353
3354 int parse_merge_opt(struct merge_options *o, const char *s)
3355 {
3356         const char *arg;
3357
3358         if (!s || !*s)
3359                 return -1;
3360         if (!strcmp(s, "ours"))
3361                 o->recursive_variant = MERGE_RECURSIVE_OURS;
3362         else if (!strcmp(s, "theirs"))
3363                 o->recursive_variant = MERGE_RECURSIVE_THEIRS;
3364         else if (!strcmp(s, "subtree"))
3365                 o->subtree_shift = "";
3366         else if (skip_prefix(s, "subtree=", &arg))
3367                 o->subtree_shift = arg;
3368         else if (!strcmp(s, "patience"))
3369                 o->xdl_opts = DIFF_WITH_ALG(o, PATIENCE_DIFF);
3370         else if (!strcmp(s, "histogram"))
3371                 o->xdl_opts = DIFF_WITH_ALG(o, HISTOGRAM_DIFF);
3372         else if (skip_prefix(s, "diff-algorithm=", &arg)) {
3373                 long value = parse_algorithm_value(arg);
3374                 if (value < 0)
3375                         return -1;
3376                 /* clear out previous settings */
3377                 DIFF_XDL_CLR(o, NEED_MINIMAL);
3378                 o->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
3379                 o->xdl_opts |= value;
3380         }
3381         else if (!strcmp(s, "ignore-space-change"))
3382                 DIFF_XDL_SET(o, IGNORE_WHITESPACE_CHANGE);
3383         else if (!strcmp(s, "ignore-all-space"))
3384                 DIFF_XDL_SET(o, IGNORE_WHITESPACE);
3385         else if (!strcmp(s, "ignore-space-at-eol"))
3386                 DIFF_XDL_SET(o, IGNORE_WHITESPACE_AT_EOL);
3387         else if (!strcmp(s, "ignore-cr-at-eol"))
3388                 DIFF_XDL_SET(o, IGNORE_CR_AT_EOL);
3389         else if (!strcmp(s, "renormalize"))
3390                 o->renormalize = 1;
3391         else if (!strcmp(s, "no-renormalize"))
3392                 o->renormalize = 0;
3393         else if (!strcmp(s, "no-renames"))
3394                 o->detect_rename = 0;
3395         else if (!strcmp(s, "find-renames")) {
3396                 o->detect_rename = 1;
3397                 o->rename_score = 0;
3398         }
3399         else if (skip_prefix(s, "find-renames=", &arg) ||
3400                  skip_prefix(s, "rename-threshold=", &arg)) {
3401                 if ((o->rename_score = parse_rename_score(&arg)) == -1 || *arg != 0)
3402                         return -1;
3403                 o->detect_rename = 1;
3404         }
3405         else
3406                 return -1;
3407         return 0;
3408 }