Merge branch 'ab/commit-m-with-fixup' into maint
[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 void flush_output(struct merge_options *o)
53 {
54         if (o->buffer_output < 2 && o->obuf.len) {
55                 fputs(o->obuf.buf, stdout);
56                 strbuf_reset(&o->obuf);
57         }
58 }
59
60 static int err(struct merge_options *o, const char *err, ...)
61 {
62         va_list params;
63
64         if (o->buffer_output < 2)
65                 flush_output(o);
66         else {
67                 strbuf_complete(&o->obuf, '\n');
68                 strbuf_addstr(&o->obuf, "error: ");
69         }
70         va_start(params, err);
71         strbuf_vaddf(&o->obuf, err, params);
72         va_end(params);
73         if (o->buffer_output > 1)
74                 strbuf_addch(&o->obuf, '\n');
75         else {
76                 error("%s", o->obuf.buf);
77                 strbuf_reset(&o->obuf);
78         }
79
80         return -1;
81 }
82
83 static struct tree *shift_tree_object(struct tree *one, struct tree *two,
84                                       const char *subtree_shift)
85 {
86         struct object_id shifted;
87
88         if (!*subtree_shift) {
89                 shift_tree(&one->object.oid, &two->object.oid, &shifted, 0);
90         } else {
91                 shift_tree_by(&one->object.oid, &two->object.oid, &shifted,
92                               subtree_shift);
93         }
94         if (!oidcmp(&two->object.oid, &shifted))
95                 return two;
96         return lookup_tree(&shifted);
97 }
98
99 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
100 {
101         struct commit *commit = alloc_commit_node();
102
103         set_merge_remote_desc(commit, comment, (struct object *)commit);
104         commit->tree = tree;
105         commit->object.parsed = 1;
106         return commit;
107 }
108
109 /*
110  * Since we use get_tree_entry(), which does not put the read object into
111  * the object pool, we cannot rely on a == b.
112  */
113 static int oid_eq(const struct object_id *a, const struct object_id *b)
114 {
115         if (!a && !b)
116                 return 2;
117         return a && b && oidcmp(a, b) == 0;
118 }
119
120 enum rename_type {
121         RENAME_NORMAL = 0,
122         RENAME_DELETE,
123         RENAME_ONE_FILE_TO_ONE,
124         RENAME_ONE_FILE_TO_TWO,
125         RENAME_TWO_FILES_TO_ONE
126 };
127
128 struct rename_conflict_info {
129         enum rename_type rename_type;
130         struct diff_filepair *pair1;
131         struct diff_filepair *pair2;
132         const char *branch1;
133         const char *branch2;
134         struct stage_data *dst_entry1;
135         struct stage_data *dst_entry2;
136         struct diff_filespec ren1_other;
137         struct diff_filespec ren2_other;
138 };
139
140 /*
141  * Since we want to write the index eventually, we cannot reuse the index
142  * for these (temporary) data.
143  */
144 struct stage_data {
145         struct {
146                 unsigned mode;
147                 struct object_id oid;
148         } stages[4];
149         struct rename_conflict_info *rename_conflict_info;
150         unsigned processed:1;
151 };
152
153 static inline void setup_rename_conflict_info(enum rename_type rename_type,
154                                               struct diff_filepair *pair1,
155                                               struct diff_filepair *pair2,
156                                               const char *branch1,
157                                               const char *branch2,
158                                               struct stage_data *dst_entry1,
159                                               struct stage_data *dst_entry2,
160                                               struct merge_options *o,
161                                               struct stage_data *src_entry1,
162                                               struct stage_data *src_entry2)
163 {
164         struct rename_conflict_info *ci = xcalloc(1, sizeof(struct rename_conflict_info));
165         ci->rename_type = rename_type;
166         ci->pair1 = pair1;
167         ci->branch1 = branch1;
168         ci->branch2 = branch2;
169
170         ci->dst_entry1 = dst_entry1;
171         dst_entry1->rename_conflict_info = ci;
172         dst_entry1->processed = 0;
173
174         assert(!pair2 == !dst_entry2);
175         if (dst_entry2) {
176                 ci->dst_entry2 = dst_entry2;
177                 ci->pair2 = pair2;
178                 dst_entry2->rename_conflict_info = ci;
179         }
180
181         if (rename_type == RENAME_TWO_FILES_TO_ONE) {
182                 /*
183                  * For each rename, there could have been
184                  * modifications on the side of history where that
185                  * file was not renamed.
186                  */
187                 int ostage1 = o->branch1 == branch1 ? 3 : 2;
188                 int ostage2 = ostage1 ^ 1;
189
190                 ci->ren1_other.path = pair1->one->path;
191                 oidcpy(&ci->ren1_other.oid, &src_entry1->stages[ostage1].oid);
192                 ci->ren1_other.mode = src_entry1->stages[ostage1].mode;
193
194                 ci->ren2_other.path = pair2->one->path;
195                 oidcpy(&ci->ren2_other.oid, &src_entry2->stages[ostage2].oid);
196                 ci->ren2_other.mode = src_entry2->stages[ostage2].mode;
197         }
198 }
199
200 static int show(struct merge_options *o, int v)
201 {
202         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
203 }
204
205 __attribute__((format (printf, 3, 4)))
206 static void output(struct merge_options *o, int v, const char *fmt, ...)
207 {
208         va_list ap;
209
210         if (!show(o, v))
211                 return;
212
213         strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
214
215         va_start(ap, fmt);
216         strbuf_vaddf(&o->obuf, fmt, ap);
217         va_end(ap);
218
219         strbuf_addch(&o->obuf, '\n');
220         if (!o->buffer_output)
221                 flush_output(o);
222 }
223
224 static void output_commit_title(struct merge_options *o, struct commit *commit)
225 {
226         strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
227         if (commit->util)
228                 strbuf_addf(&o->obuf, "virtual %s\n",
229                         merge_remote_util(commit)->name);
230         else {
231                 strbuf_add_unique_abbrev(&o->obuf, commit->object.oid.hash,
232                                          DEFAULT_ABBREV);
233                 strbuf_addch(&o->obuf, ' ');
234                 if (parse_commit(commit) != 0)
235                         strbuf_addstr(&o->obuf, _("(bad commit)\n"));
236                 else {
237                         const char *title;
238                         const char *msg = get_commit_buffer(commit, NULL);
239                         int len = find_commit_subject(msg, &title);
240                         if (len)
241                                 strbuf_addf(&o->obuf, "%.*s\n", len, title);
242                         unuse_commit_buffer(commit, msg);
243                 }
244         }
245         flush_output(o);
246 }
247
248 static int add_cacheinfo(struct merge_options *o,
249                 unsigned int mode, const struct object_id *oid,
250                 const char *path, int stage, int refresh, int options)
251 {
252         struct cache_entry *ce;
253         int ret;
254
255         ce = make_cache_entry(mode, oid ? oid->hash : null_sha1, path, stage, 0);
256         if (!ce)
257                 return err(o, _("addinfo_cache failed for path '%s'"), path);
258
259         ret = add_cache_entry(ce, options);
260         if (refresh) {
261                 struct cache_entry *nce;
262
263                 nce = refresh_cache_entry(ce, CE_MATCH_REFRESH | CE_MATCH_IGNORE_MISSING);
264                 if (!nce)
265                         return err(o, _("addinfo_cache failed for path '%s'"), path);
266                 if (nce != ce)
267                         ret = add_cache_entry(nce, options);
268         }
269         return ret;
270 }
271
272 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
273 {
274         parse_tree(tree);
275         init_tree_desc(desc, tree->buffer, tree->size);
276 }
277
278 static int git_merge_trees(int index_only,
279                            struct tree *common,
280                            struct tree *head,
281                            struct tree *merge)
282 {
283         int rc;
284         struct tree_desc t[3];
285         struct unpack_trees_options opts;
286
287         memset(&opts, 0, sizeof(opts));
288         if (index_only)
289                 opts.index_only = 1;
290         else
291                 opts.update = 1;
292         opts.merge = 1;
293         opts.head_idx = 2;
294         opts.fn = threeway_merge;
295         opts.src_index = &the_index;
296         opts.dst_index = &the_index;
297         setup_unpack_trees_porcelain(&opts, "merge");
298
299         init_tree_desc_from_tree(t+0, common);
300         init_tree_desc_from_tree(t+1, head);
301         init_tree_desc_from_tree(t+2, merge);
302
303         rc = unpack_trees(3, t, &opts);
304         cache_tree_free(&active_cache_tree);
305         return rc;
306 }
307
308 struct tree *write_tree_from_memory(struct merge_options *o)
309 {
310         struct tree *result = NULL;
311
312         if (unmerged_cache()) {
313                 int i;
314                 fprintf(stderr, "BUG: There are unmerged index entries:\n");
315                 for (i = 0; i < active_nr; i++) {
316                         const struct cache_entry *ce = active_cache[i];
317                         if (ce_stage(ce))
318                                 fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
319                                         (int)ce_namelen(ce), ce->name);
320                 }
321                 die("BUG: unmerged index entries in merge-recursive.c");
322         }
323
324         if (!active_cache_tree)
325                 active_cache_tree = cache_tree();
326
327         if (!cache_tree_fully_valid(active_cache_tree) &&
328             cache_tree_update(&the_index, 0) < 0) {
329                 err(o, _("error building trees"));
330                 return NULL;
331         }
332
333         result = lookup_tree(&active_cache_tree->oid);
334
335         return result;
336 }
337
338 static int save_files_dirs(const unsigned char *sha1,
339                 struct strbuf *base, const char *path,
340                 unsigned int mode, int stage, void *context)
341 {
342         struct path_hashmap_entry *entry;
343         int baselen = base->len;
344         struct merge_options *o = context;
345
346         strbuf_addstr(base, path);
347
348         FLEX_ALLOC_MEM(entry, path, base->buf, base->len);
349         hashmap_entry_init(entry, path_hash(entry->path));
350         hashmap_add(&o->current_file_dir_set, entry);
351
352         strbuf_setlen(base, baselen);
353         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
354 }
355
356 static void get_files_dirs(struct merge_options *o, struct tree *tree)
357 {
358         struct pathspec match_all;
359         memset(&match_all, 0, sizeof(match_all));
360         read_tree_recursive(tree, "", 0, 0, &match_all, save_files_dirs, o);
361 }
362
363 /*
364  * Returns an index_entry instance which doesn't have to correspond to
365  * a real cache entry in Git's index.
366  */
367 static struct stage_data *insert_stage_data(const char *path,
368                 struct tree *o, struct tree *a, struct tree *b,
369                 struct string_list *entries)
370 {
371         struct string_list_item *item;
372         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
373         get_tree_entry(o->object.oid.hash, path,
374                         e->stages[1].oid.hash, &e->stages[1].mode);
375         get_tree_entry(a->object.oid.hash, path,
376                         e->stages[2].oid.hash, &e->stages[2].mode);
377         get_tree_entry(b->object.oid.hash, path,
378                         e->stages[3].oid.hash, &e->stages[3].mode);
379         item = string_list_insert(entries, path);
380         item->util = e;
381         return e;
382 }
383
384 /*
385  * Create a dictionary mapping file names to stage_data objects. The
386  * dictionary contains one entry for every path with a non-zero stage entry.
387  */
388 static struct string_list *get_unmerged(void)
389 {
390         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
391         int i;
392
393         unmerged->strdup_strings = 1;
394
395         for (i = 0; i < active_nr; i++) {
396                 struct string_list_item *item;
397                 struct stage_data *e;
398                 const struct cache_entry *ce = active_cache[i];
399                 if (!ce_stage(ce))
400                         continue;
401
402                 item = string_list_lookup(unmerged, ce->name);
403                 if (!item) {
404                         item = string_list_insert(unmerged, ce->name);
405                         item->util = xcalloc(1, sizeof(struct stage_data));
406                 }
407                 e = item->util;
408                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
409                 oidcpy(&e->stages[ce_stage(ce)].oid, &ce->oid);
410         }
411
412         return unmerged;
413 }
414
415 static int string_list_df_name_compare(const char *one, const char *two)
416 {
417         int onelen = strlen(one);
418         int twolen = strlen(two);
419         /*
420          * Here we only care that entries for D/F conflicts are
421          * adjacent, in particular with the file of the D/F conflict
422          * appearing before files below the corresponding directory.
423          * The order of the rest of the list is irrelevant for us.
424          *
425          * To achieve this, we sort with df_name_compare and provide
426          * the mode S_IFDIR so that D/F conflicts will sort correctly.
427          * We use the mode S_IFDIR for everything else for simplicity,
428          * since in other cases any changes in their order due to
429          * sorting cause no problems for us.
430          */
431         int cmp = df_name_compare(one, onelen, S_IFDIR,
432                                   two, twolen, S_IFDIR);
433         /*
434          * Now that 'foo' and 'foo/bar' compare equal, we have to make sure
435          * that 'foo' comes before 'foo/bar'.
436          */
437         if (cmp)
438                 return cmp;
439         return onelen - twolen;
440 }
441
442 static void record_df_conflict_files(struct merge_options *o,
443                                      struct string_list *entries)
444 {
445         /* If there is a D/F conflict and the file for such a conflict
446          * currently exist in the working tree, we want to allow it to be
447          * removed to make room for the corresponding directory if needed.
448          * The files underneath the directories of such D/F conflicts will
449          * be processed before the corresponding file involved in the D/F
450          * conflict.  If the D/F directory ends up being removed by the
451          * merge, then we won't have to touch the D/F file.  If the D/F
452          * directory needs to be written to the working copy, then the D/F
453          * file will simply be removed (in make_room_for_path()) to make
454          * room for the necessary paths.  Note that if both the directory
455          * and the file need to be present, then the D/F file will be
456          * reinstated with a new unique name at the time it is processed.
457          */
458         struct string_list df_sorted_entries = STRING_LIST_INIT_NODUP;
459         const char *last_file = NULL;
460         int last_len = 0;
461         int i;
462
463         /*
464          * If we're merging merge-bases, we don't want to bother with
465          * any working directory changes.
466          */
467         if (o->call_depth)
468                 return;
469
470         /* Ensure D/F conflicts are adjacent in the entries list. */
471         for (i = 0; i < entries->nr; i++) {
472                 struct string_list_item *next = &entries->items[i];
473                 string_list_append(&df_sorted_entries, next->string)->util =
474                                    next->util;
475         }
476         df_sorted_entries.cmp = string_list_df_name_compare;
477         string_list_sort(&df_sorted_entries);
478
479         string_list_clear(&o->df_conflict_file_set, 1);
480         for (i = 0; i < df_sorted_entries.nr; i++) {
481                 const char *path = df_sorted_entries.items[i].string;
482                 int len = strlen(path);
483                 struct stage_data *e = df_sorted_entries.items[i].util;
484
485                 /*
486                  * Check if last_file & path correspond to a D/F conflict;
487                  * i.e. whether path is last_file+'/'+<something>.
488                  * If so, record that it's okay to remove last_file to make
489                  * room for path and friends if needed.
490                  */
491                 if (last_file &&
492                     len > last_len &&
493                     memcmp(path, last_file, last_len) == 0 &&
494                     path[last_len] == '/') {
495                         string_list_insert(&o->df_conflict_file_set, last_file);
496                 }
497
498                 /*
499                  * Determine whether path could exist as a file in the
500                  * working directory as a possible D/F conflict.  This
501                  * will only occur when it exists in stage 2 as a
502                  * file.
503                  */
504                 if (S_ISREG(e->stages[2].mode) || S_ISLNK(e->stages[2].mode)) {
505                         last_file = path;
506                         last_len = len;
507                 } else {
508                         last_file = NULL;
509                 }
510         }
511         string_list_clear(&df_sorted_entries, 0);
512 }
513
514 struct rename {
515         struct diff_filepair *pair;
516         struct stage_data *src_entry;
517         struct stage_data *dst_entry;
518         unsigned processed:1;
519 };
520
521 /*
522  * Get information of all renames which occurred between 'o_tree' and
523  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
524  * 'b_tree') to be able to associate the correct cache entries with
525  * the rename information. 'tree' is always equal to either a_tree or b_tree.
526  */
527 static struct string_list *get_renames(struct merge_options *o,
528                                        struct tree *tree,
529                                        struct tree *o_tree,
530                                        struct tree *a_tree,
531                                        struct tree *b_tree,
532                                        struct string_list *entries)
533 {
534         int i;
535         struct string_list *renames;
536         struct diff_options opts;
537
538         renames = xcalloc(1, sizeof(struct string_list));
539         if (!o->detect_rename)
540                 return renames;
541
542         diff_setup(&opts);
543         opts.flags.recursive = 1;
544         opts.flags.rename_empty = 0;
545         opts.detect_rename = DIFF_DETECT_RENAME;
546         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
547                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
548                             1000;
549         opts.rename_score = o->rename_score;
550         opts.show_rename_progress = o->show_rename_progress;
551         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
552         diff_setup_done(&opts);
553         diff_tree_oid(&o_tree->object.oid, &tree->object.oid, "", &opts);
554         diffcore_std(&opts);
555         if (opts.needed_rename_limit > o->needed_rename_limit)
556                 o->needed_rename_limit = opts.needed_rename_limit;
557         for (i = 0; i < diff_queued_diff.nr; ++i) {
558                 struct string_list_item *item;
559                 struct rename *re;
560                 struct diff_filepair *pair = diff_queued_diff.queue[i];
561                 if (pair->status != 'R') {
562                         diff_free_filepair(pair);
563                         continue;
564                 }
565                 re = xmalloc(sizeof(*re));
566                 re->processed = 0;
567                 re->pair = pair;
568                 item = string_list_lookup(entries, re->pair->one->path);
569                 if (!item)
570                         re->src_entry = insert_stage_data(re->pair->one->path,
571                                         o_tree, a_tree, b_tree, entries);
572                 else
573                         re->src_entry = item->util;
574
575                 item = string_list_lookup(entries, re->pair->two->path);
576                 if (!item)
577                         re->dst_entry = insert_stage_data(re->pair->two->path,
578                                         o_tree, a_tree, b_tree, entries);
579                 else
580                         re->dst_entry = item->util;
581                 item = string_list_insert(renames, pair->one->path);
582                 item->util = re;
583         }
584         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
585         diff_queued_diff.nr = 0;
586         diff_flush(&opts);
587         return renames;
588 }
589
590 static int update_stages(struct merge_options *opt, const char *path,
591                          const struct diff_filespec *o,
592                          const struct diff_filespec *a,
593                          const struct diff_filespec *b)
594 {
595
596         /*
597          * NOTE: It is usually a bad idea to call update_stages on a path
598          * before calling update_file on that same path, since it can
599          * sometimes lead to spurious "refusing to lose untracked file..."
600          * messages from update_file (via make_room_for path via
601          * would_lose_untracked).  Instead, reverse the order of the calls
602          * (executing update_file first and then update_stages).
603          */
604         int clear = 1;
605         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_SKIP_DFCHECK;
606         if (clear)
607                 if (remove_file_from_cache(path))
608                         return -1;
609         if (o)
610                 if (add_cacheinfo(opt, o->mode, &o->oid, path, 1, 0, options))
611                         return -1;
612         if (a)
613                 if (add_cacheinfo(opt, a->mode, &a->oid, path, 2, 0, options))
614                         return -1;
615         if (b)
616                 if (add_cacheinfo(opt, b->mode, &b->oid, path, 3, 0, options))
617                         return -1;
618         return 0;
619 }
620
621 static void update_entry(struct stage_data *entry,
622                          struct diff_filespec *o,
623                          struct diff_filespec *a,
624                          struct diff_filespec *b)
625 {
626         entry->processed = 0;
627         entry->stages[1].mode = o->mode;
628         entry->stages[2].mode = a->mode;
629         entry->stages[3].mode = b->mode;
630         oidcpy(&entry->stages[1].oid, &o->oid);
631         oidcpy(&entry->stages[2].oid, &a->oid);
632         oidcpy(&entry->stages[3].oid, &b->oid);
633 }
634
635 static int remove_file(struct merge_options *o, int clean,
636                        const char *path, int no_wd)
637 {
638         int update_cache = o->call_depth || clean;
639         int update_working_directory = !o->call_depth && !no_wd;
640
641         if (update_cache) {
642                 if (remove_file_from_cache(path))
643                         return -1;
644         }
645         if (update_working_directory) {
646                 if (ignore_case) {
647                         struct cache_entry *ce;
648                         ce = cache_file_exists(path, strlen(path), ignore_case);
649                         if (ce && ce_stage(ce) == 0 && strcmp(path, ce->name))
650                                 return 0;
651                 }
652                 if (remove_path(path))
653                         return -1;
654         }
655         return 0;
656 }
657
658 /* add a string to a strbuf, but converting "/" to "_" */
659 static void add_flattened_path(struct strbuf *out, const char *s)
660 {
661         size_t i = out->len;
662         strbuf_addstr(out, s);
663         for (; i < out->len; i++)
664                 if (out->buf[i] == '/')
665                         out->buf[i] = '_';
666 }
667
668 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
669 {
670         struct path_hashmap_entry *entry;
671         struct strbuf newpath = STRBUF_INIT;
672         int suffix = 0;
673         size_t base_len;
674
675         strbuf_addf(&newpath, "%s~", path);
676         add_flattened_path(&newpath, branch);
677
678         base_len = newpath.len;
679         while (hashmap_get_from_hash(&o->current_file_dir_set,
680                                      path_hash(newpath.buf), newpath.buf) ||
681                (!o->call_depth && file_exists(newpath.buf))) {
682                 strbuf_setlen(&newpath, base_len);
683                 strbuf_addf(&newpath, "_%d", suffix++);
684         }
685
686         FLEX_ALLOC_MEM(entry, path, newpath.buf, newpath.len);
687         hashmap_entry_init(entry, path_hash(entry->path));
688         hashmap_add(&o->current_file_dir_set, entry);
689         return strbuf_detach(&newpath, NULL);
690 }
691
692 /**
693  * Check whether a directory in the index is in the way of an incoming
694  * file.  Return 1 if so.  If check_working_copy is non-zero, also
695  * check the working directory.  If empty_ok is non-zero, also return
696  * 0 in the case where the working-tree dir exists but is empty.
697  */
698 static int dir_in_way(const char *path, int check_working_copy, int empty_ok)
699 {
700         int pos;
701         struct strbuf dirpath = STRBUF_INIT;
702         struct stat st;
703
704         strbuf_addstr(&dirpath, path);
705         strbuf_addch(&dirpath, '/');
706
707         pos = cache_name_pos(dirpath.buf, dirpath.len);
708
709         if (pos < 0)
710                 pos = -1 - pos;
711         if (pos < active_nr &&
712             !strncmp(dirpath.buf, active_cache[pos]->name, dirpath.len)) {
713                 strbuf_release(&dirpath);
714                 return 1;
715         }
716
717         strbuf_release(&dirpath);
718         return check_working_copy && !lstat(path, &st) && S_ISDIR(st.st_mode) &&
719                 !(empty_ok && is_empty_dir(path));
720 }
721
722 static int was_tracked(const char *path)
723 {
724         int pos = cache_name_pos(path, strlen(path));
725
726         if (0 <= pos)
727                 /* we have been tracking this path */
728                 return 1;
729
730         /*
731          * Look for an unmerged entry for the path,
732          * specifically stage #2, which would indicate
733          * that "our" side before the merge started
734          * had the path tracked (and resulted in a conflict).
735          */
736         for (pos = -1 - pos;
737              pos < active_nr && !strcmp(path, active_cache[pos]->name);
738              pos++)
739                 if (ce_stage(active_cache[pos]) == 2)
740                         return 1;
741         return 0;
742 }
743
744 static int would_lose_untracked(const char *path)
745 {
746         return !was_tracked(path) && file_exists(path);
747 }
748
749 static int make_room_for_path(struct merge_options *o, const char *path)
750 {
751         int status, i;
752         const char *msg = _("failed to create path '%s'%s");
753
754         /* Unlink any D/F conflict files that are in the way */
755         for (i = 0; i < o->df_conflict_file_set.nr; i++) {
756                 const char *df_path = o->df_conflict_file_set.items[i].string;
757                 size_t pathlen = strlen(path);
758                 size_t df_pathlen = strlen(df_path);
759                 if (df_pathlen < pathlen &&
760                     path[df_pathlen] == '/' &&
761                     strncmp(path, df_path, df_pathlen) == 0) {
762                         output(o, 3,
763                                _("Removing %s to make room for subdirectory\n"),
764                                df_path);
765                         unlink(df_path);
766                         unsorted_string_list_delete_item(&o->df_conflict_file_set,
767                                                          i, 0);
768                         break;
769                 }
770         }
771
772         /* Make sure leading directories are created */
773         status = safe_create_leading_directories_const(path);
774         if (status) {
775                 if (status == SCLD_EXISTS)
776                         /* something else exists */
777                         return err(o, msg, path, _(": perhaps a D/F conflict?"));
778                 return err(o, msg, path, "");
779         }
780
781         /*
782          * Do not unlink a file in the work tree if we are not
783          * tracking it.
784          */
785         if (would_lose_untracked(path))
786                 return err(o, _("refusing to lose untracked file at '%s'"),
787                              path);
788
789         /* Successful unlink is good.. */
790         if (!unlink(path))
791                 return 0;
792         /* .. and so is no existing file */
793         if (errno == ENOENT)
794                 return 0;
795         /* .. but not some other error (who really cares what?) */
796         return err(o, msg, path, _(": perhaps a D/F conflict?"));
797 }
798
799 static int update_file_flags(struct merge_options *o,
800                              const struct object_id *oid,
801                              unsigned mode,
802                              const char *path,
803                              int update_cache,
804                              int update_wd)
805 {
806         int ret = 0;
807
808         if (o->call_depth)
809                 update_wd = 0;
810
811         if (update_wd) {
812                 enum object_type type;
813                 void *buf;
814                 unsigned long size;
815
816                 if (S_ISGITLINK(mode)) {
817                         /*
818                          * We may later decide to recursively descend into
819                          * the submodule directory and update its index
820                          * and/or work tree, but we do not do that now.
821                          */
822                         update_wd = 0;
823                         goto update_index;
824                 }
825
826                 buf = read_sha1_file(oid->hash, &type, &size);
827                 if (!buf)
828                         return err(o, _("cannot read object %s '%s'"), oid_to_hex(oid), path);
829                 if (type != OBJ_BLOB) {
830                         ret = err(o, _("blob expected for %s '%s'"), oid_to_hex(oid), path);
831                         goto free_buf;
832                 }
833                 if (S_ISREG(mode)) {
834                         struct strbuf strbuf = STRBUF_INIT;
835                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
836                                 free(buf);
837                                 size = strbuf.len;
838                                 buf = strbuf_detach(&strbuf, NULL);
839                         }
840                 }
841
842                 if (make_room_for_path(o, path) < 0) {
843                         update_wd = 0;
844                         goto free_buf;
845                 }
846                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
847                         int fd;
848                         if (mode & 0100)
849                                 mode = 0777;
850                         else
851                                 mode = 0666;
852                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
853                         if (fd < 0) {
854                                 ret = err(o, _("failed to open '%s': %s"),
855                                           path, strerror(errno));
856                                 goto free_buf;
857                         }
858                         write_in_full(fd, buf, size);
859                         close(fd);
860                 } else if (S_ISLNK(mode)) {
861                         char *lnk = xmemdupz(buf, size);
862                         safe_create_leading_directories_const(path);
863                         unlink(path);
864                         if (symlink(lnk, path))
865                                 ret = err(o, _("failed to symlink '%s': %s"),
866                                         path, strerror(errno));
867                         free(lnk);
868                 } else
869                         ret = err(o,
870                                   _("do not know what to do with %06o %s '%s'"),
871                                   mode, oid_to_hex(oid), path);
872  free_buf:
873                 free(buf);
874         }
875  update_index:
876         if (!ret && update_cache)
877                 add_cacheinfo(o, mode, oid, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
878         return ret;
879 }
880
881 static int update_file(struct merge_options *o,
882                        int clean,
883                        const struct object_id *oid,
884                        unsigned mode,
885                        const char *path)
886 {
887         return update_file_flags(o, oid, mode, path, o->call_depth || clean, !o->call_depth);
888 }
889
890 /* Low level file merging, update and removal */
891
892 struct merge_file_info {
893         struct object_id oid;
894         unsigned mode;
895         unsigned clean:1,
896                  merge:1;
897 };
898
899 static int merge_3way(struct merge_options *o,
900                       mmbuffer_t *result_buf,
901                       const struct diff_filespec *one,
902                       const struct diff_filespec *a,
903                       const struct diff_filespec *b,
904                       const char *branch1,
905                       const char *branch2)
906 {
907         mmfile_t orig, src1, src2;
908         struct ll_merge_options ll_opts = {0};
909         char *base_name, *name1, *name2;
910         int merge_status;
911
912         ll_opts.renormalize = o->renormalize;
913         ll_opts.xdl_opts = o->xdl_opts;
914
915         if (o->call_depth) {
916                 ll_opts.virtual_ancestor = 1;
917                 ll_opts.variant = 0;
918         } else {
919                 switch (o->recursive_variant) {
920                 case MERGE_RECURSIVE_OURS:
921                         ll_opts.variant = XDL_MERGE_FAVOR_OURS;
922                         break;
923                 case MERGE_RECURSIVE_THEIRS:
924                         ll_opts.variant = XDL_MERGE_FAVOR_THEIRS;
925                         break;
926                 default:
927                         ll_opts.variant = 0;
928                         break;
929                 }
930         }
931
932         if (strcmp(a->path, b->path) ||
933             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
934                 base_name = o->ancestor == NULL ? NULL :
935                         mkpathdup("%s:%s", o->ancestor, one->path);
936                 name1 = mkpathdup("%s:%s", branch1, a->path);
937                 name2 = mkpathdup("%s:%s", branch2, b->path);
938         } else {
939                 base_name = o->ancestor == NULL ? NULL :
940                         mkpathdup("%s", o->ancestor);
941                 name1 = mkpathdup("%s", branch1);
942                 name2 = mkpathdup("%s", branch2);
943         }
944
945         read_mmblob(&orig, &one->oid);
946         read_mmblob(&src1, &a->oid);
947         read_mmblob(&src2, &b->oid);
948
949         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
950                                 &src1, name1, &src2, name2, &ll_opts);
951
952         free(base_name);
953         free(name1);
954         free(name2);
955         free(orig.ptr);
956         free(src1.ptr);
957         free(src2.ptr);
958         return merge_status;
959 }
960
961 static int merge_file_1(struct merge_options *o,
962                                            const struct diff_filespec *one,
963                                            const struct diff_filespec *a,
964                                            const struct diff_filespec *b,
965                                            const char *branch1,
966                                            const char *branch2,
967                                            struct merge_file_info *result)
968 {
969         result->merge = 0;
970         result->clean = 1;
971
972         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
973                 result->clean = 0;
974                 if (S_ISREG(a->mode)) {
975                         result->mode = a->mode;
976                         oidcpy(&result->oid, &a->oid);
977                 } else {
978                         result->mode = b->mode;
979                         oidcpy(&result->oid, &b->oid);
980                 }
981         } else {
982                 if (!oid_eq(&a->oid, &one->oid) && !oid_eq(&b->oid, &one->oid))
983                         result->merge = 1;
984
985                 /*
986                  * Merge modes
987                  */
988                 if (a->mode == b->mode || a->mode == one->mode)
989                         result->mode = b->mode;
990                 else {
991                         result->mode = a->mode;
992                         if (b->mode != one->mode) {
993                                 result->clean = 0;
994                                 result->merge = 1;
995                         }
996                 }
997
998                 if (oid_eq(&a->oid, &b->oid) || oid_eq(&a->oid, &one->oid))
999                         oidcpy(&result->oid, &b->oid);
1000                 else if (oid_eq(&b->oid, &one->oid))
1001                         oidcpy(&result->oid, &a->oid);
1002                 else if (S_ISREG(a->mode)) {
1003                         mmbuffer_t result_buf;
1004                         int ret = 0, merge_status;
1005
1006                         merge_status = merge_3way(o, &result_buf, one, a, b,
1007                                                   branch1, branch2);
1008
1009                         if ((merge_status < 0) || !result_buf.ptr)
1010                                 ret = err(o, _("Failed to execute internal merge"));
1011
1012                         if (!ret && write_sha1_file(result_buf.ptr, result_buf.size,
1013                                                     blob_type, result->oid.hash))
1014                                 ret = err(o, _("Unable to add %s to database"),
1015                                           a->path);
1016
1017                         free(result_buf.ptr);
1018                         if (ret)
1019                                 return ret;
1020                         result->clean = (merge_status == 0);
1021                 } else if (S_ISGITLINK(a->mode)) {
1022                         result->clean = merge_submodule(&result->oid,
1023                                                        one->path,
1024                                                        &one->oid,
1025                                                        &a->oid,
1026                                                        &b->oid,
1027                                                        !o->call_depth);
1028                 } else if (S_ISLNK(a->mode)) {
1029                         switch (o->recursive_variant) {
1030                         case MERGE_RECURSIVE_NORMAL:
1031                                 oidcpy(&result->oid, &a->oid);
1032                                 if (!oid_eq(&a->oid, &b->oid))
1033                                         result->clean = 0;
1034                                 break;
1035                         case MERGE_RECURSIVE_OURS:
1036                                 oidcpy(&result->oid, &a->oid);
1037                                 break;
1038                         case MERGE_RECURSIVE_THEIRS:
1039                                 oidcpy(&result->oid, &b->oid);
1040                                 break;
1041                         }
1042                 } else
1043                         die("BUG: unsupported object type in the tree");
1044         }
1045
1046         return 0;
1047 }
1048
1049 static int merge_file_special_markers(struct merge_options *o,
1050                            const struct diff_filespec *one,
1051                            const struct diff_filespec *a,
1052                            const struct diff_filespec *b,
1053                            const char *branch1,
1054                            const char *filename1,
1055                            const char *branch2,
1056                            const char *filename2,
1057                            struct merge_file_info *mfi)
1058 {
1059         char *side1 = NULL;
1060         char *side2 = NULL;
1061         int ret;
1062
1063         if (filename1)
1064                 side1 = xstrfmt("%s:%s", branch1, filename1);
1065         if (filename2)
1066                 side2 = xstrfmt("%s:%s", branch2, filename2);
1067
1068         ret = merge_file_1(o, one, a, b,
1069                            side1 ? side1 : branch1,
1070                            side2 ? side2 : branch2, mfi);
1071         free(side1);
1072         free(side2);
1073         return ret;
1074 }
1075
1076 static int merge_file_one(struct merge_options *o,
1077                                          const char *path,
1078                                          const struct object_id *o_oid, int o_mode,
1079                                          const struct object_id *a_oid, int a_mode,
1080                                          const struct object_id *b_oid, int b_mode,
1081                                          const char *branch1,
1082                                          const char *branch2,
1083                                          struct merge_file_info *mfi)
1084 {
1085         struct diff_filespec one, a, b;
1086
1087         one.path = a.path = b.path = (char *)path;
1088         oidcpy(&one.oid, o_oid);
1089         one.mode = o_mode;
1090         oidcpy(&a.oid, a_oid);
1091         a.mode = a_mode;
1092         oidcpy(&b.oid, b_oid);
1093         b.mode = b_mode;
1094         return merge_file_1(o, &one, &a, &b, branch1, branch2, mfi);
1095 }
1096
1097 static int handle_change_delete(struct merge_options *o,
1098                                  const char *path, const char *old_path,
1099                                  const struct object_id *o_oid, int o_mode,
1100                                  const struct object_id *changed_oid,
1101                                  int changed_mode,
1102                                  const char *change_branch,
1103                                  const char *delete_branch,
1104                                  const char *change, const char *change_past)
1105 {
1106         char *alt_path = NULL;
1107         const char *update_path = path;
1108         int ret = 0;
1109
1110         if (dir_in_way(path, !o->call_depth, 0)) {
1111                 update_path = alt_path = unique_path(o, path, change_branch);
1112         }
1113
1114         if (o->call_depth) {
1115                 /*
1116                  * We cannot arbitrarily accept either a_sha or b_sha as
1117                  * correct; since there is no true "middle point" between
1118                  * them, simply reuse the base version for virtual merge base.
1119                  */
1120                 ret = remove_file_from_cache(path);
1121                 if (!ret)
1122                         ret = update_file(o, 0, o_oid, o_mode, update_path);
1123         } else {
1124                 if (!alt_path) {
1125                         if (!old_path) {
1126                                 output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1127                                        "and %s in %s. Version %s of %s left in tree."),
1128                                        change, path, delete_branch, change_past,
1129                                        change_branch, change_branch, path);
1130                         } else {
1131                                 output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1132                                        "and %s to %s in %s. Version %s of %s left in tree."),
1133                                        change, old_path, delete_branch, change_past, path,
1134                                        change_branch, change_branch, path);
1135                         }
1136                 } else {
1137                         if (!old_path) {
1138                                 output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1139                                        "and %s in %s. Version %s of %s left in tree at %s."),
1140                                        change, path, delete_branch, change_past,
1141                                        change_branch, change_branch, path, alt_path);
1142                         } else {
1143                                 output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1144                                        "and %s to %s in %s. Version %s of %s left in tree at %s."),
1145                                        change, old_path, delete_branch, change_past, path,
1146                                        change_branch, change_branch, path, alt_path);
1147                         }
1148                 }
1149                 /*
1150                  * No need to call update_file() on path when change_branch ==
1151                  * o->branch1 && !alt_path, since that would needlessly touch
1152                  * path.  We could call update_file_flags() with update_cache=0
1153                  * and update_wd=0, but that's a no-op.
1154                  */
1155                 if (change_branch != o->branch1 || alt_path)
1156                         ret = update_file(o, 0, changed_oid, changed_mode, update_path);
1157         }
1158         free(alt_path);
1159
1160         return ret;
1161 }
1162
1163 static int conflict_rename_delete(struct merge_options *o,
1164                                    struct diff_filepair *pair,
1165                                    const char *rename_branch,
1166                                    const char *delete_branch)
1167 {
1168         const struct diff_filespec *orig = pair->one;
1169         const struct diff_filespec *dest = pair->two;
1170
1171         if (handle_change_delete(o,
1172                                  o->call_depth ? orig->path : dest->path,
1173                                  o->call_depth ? NULL : orig->path,
1174                                  &orig->oid, orig->mode,
1175                                  &dest->oid, dest->mode,
1176                                  rename_branch, delete_branch,
1177                                  _("rename"), _("renamed")))
1178                 return -1;
1179
1180         if (o->call_depth)
1181                 return remove_file_from_cache(dest->path);
1182         else
1183                 return update_stages(o, dest->path, NULL,
1184                                      rename_branch == o->branch1 ? dest : NULL,
1185                                      rename_branch == o->branch1 ? NULL : dest);
1186 }
1187
1188 static struct diff_filespec *filespec_from_entry(struct diff_filespec *target,
1189                                                  struct stage_data *entry,
1190                                                  int stage)
1191 {
1192         struct object_id *oid = &entry->stages[stage].oid;
1193         unsigned mode = entry->stages[stage].mode;
1194         if (mode == 0 || is_null_oid(oid))
1195                 return NULL;
1196         oidcpy(&target->oid, oid);
1197         target->mode = mode;
1198         return target;
1199 }
1200
1201 static int handle_file(struct merge_options *o,
1202                         struct diff_filespec *rename,
1203                         int stage,
1204                         struct rename_conflict_info *ci)
1205 {
1206         char *dst_name = rename->path;
1207         struct stage_data *dst_entry;
1208         const char *cur_branch, *other_branch;
1209         struct diff_filespec other;
1210         struct diff_filespec *add;
1211         int ret;
1212
1213         if (stage == 2) {
1214                 dst_entry = ci->dst_entry1;
1215                 cur_branch = ci->branch1;
1216                 other_branch = ci->branch2;
1217         } else {
1218                 dst_entry = ci->dst_entry2;
1219                 cur_branch = ci->branch2;
1220                 other_branch = ci->branch1;
1221         }
1222
1223         add = filespec_from_entry(&other, dst_entry, stage ^ 1);
1224         if (add) {
1225                 char *add_name = unique_path(o, rename->path, other_branch);
1226                 if (update_file(o, 0, &add->oid, add->mode, add_name))
1227                         return -1;
1228
1229                 remove_file(o, 0, rename->path, 0);
1230                 dst_name = unique_path(o, rename->path, cur_branch);
1231         } else {
1232                 if (dir_in_way(rename->path, !o->call_depth, 0)) {
1233                         dst_name = unique_path(o, rename->path, cur_branch);
1234                         output(o, 1, _("%s is a directory in %s adding as %s instead"),
1235                                rename->path, other_branch, dst_name);
1236                 }
1237         }
1238         if ((ret = update_file(o, 0, &rename->oid, rename->mode, dst_name)))
1239                 ; /* fall through, do allow dst_name to be released */
1240         else if (stage == 2)
1241                 ret = update_stages(o, rename->path, NULL, rename, add);
1242         else
1243                 ret = update_stages(o, rename->path, NULL, add, rename);
1244
1245         if (dst_name != rename->path)
1246                 free(dst_name);
1247
1248         return ret;
1249 }
1250
1251 static int conflict_rename_rename_1to2(struct merge_options *o,
1252                                         struct rename_conflict_info *ci)
1253 {
1254         /* One file was renamed in both branches, but to different names. */
1255         struct diff_filespec *one = ci->pair1->one;
1256         struct diff_filespec *a = ci->pair1->two;
1257         struct diff_filespec *b = ci->pair2->two;
1258
1259         output(o, 1, _("CONFLICT (rename/rename): "
1260                "Rename \"%s\"->\"%s\" in branch \"%s\" "
1261                "rename \"%s\"->\"%s\" in \"%s\"%s"),
1262                one->path, a->path, ci->branch1,
1263                one->path, b->path, ci->branch2,
1264                o->call_depth ? _(" (left unresolved)") : "");
1265         if (o->call_depth) {
1266                 struct merge_file_info mfi;
1267                 struct diff_filespec other;
1268                 struct diff_filespec *add;
1269                 if (merge_file_one(o, one->path,
1270                                  &one->oid, one->mode,
1271                                  &a->oid, a->mode,
1272                                  &b->oid, b->mode,
1273                                  ci->branch1, ci->branch2, &mfi))
1274                         return -1;
1275
1276                 /*
1277                  * FIXME: For rename/add-source conflicts (if we could detect
1278                  * such), this is wrong.  We should instead find a unique
1279                  * pathname and then either rename the add-source file to that
1280                  * unique path, or use that unique path instead of src here.
1281                  */
1282                 if (update_file(o, 0, &mfi.oid, mfi.mode, one->path))
1283                         return -1;
1284
1285                 /*
1286                  * Above, we put the merged content at the merge-base's
1287                  * path.  Now we usually need to delete both a->path and
1288                  * b->path.  However, the rename on each side of the merge
1289                  * could also be involved in a rename/add conflict.  In
1290                  * such cases, we should keep the added file around,
1291                  * resolving the conflict at that path in its favor.
1292                  */
1293                 add = filespec_from_entry(&other, ci->dst_entry1, 2 ^ 1);
1294                 if (add) {
1295                         if (update_file(o, 0, &add->oid, add->mode, a->path))
1296                                 return -1;
1297                 }
1298                 else
1299                         remove_file_from_cache(a->path);
1300                 add = filespec_from_entry(&other, ci->dst_entry2, 3 ^ 1);
1301                 if (add) {
1302                         if (update_file(o, 0, &add->oid, add->mode, b->path))
1303                                 return -1;
1304                 }
1305                 else
1306                         remove_file_from_cache(b->path);
1307         } else if (handle_file(o, a, 2, ci) || handle_file(o, b, 3, ci))
1308                 return -1;
1309
1310         return 0;
1311 }
1312
1313 static int conflict_rename_rename_2to1(struct merge_options *o,
1314                                         struct rename_conflict_info *ci)
1315 {
1316         /* Two files, a & b, were renamed to the same thing, c. */
1317         struct diff_filespec *a = ci->pair1->one;
1318         struct diff_filespec *b = ci->pair2->one;
1319         struct diff_filespec *c1 = ci->pair1->two;
1320         struct diff_filespec *c2 = ci->pair2->two;
1321         char *path = c1->path; /* == c2->path */
1322         struct merge_file_info mfi_c1;
1323         struct merge_file_info mfi_c2;
1324         int ret;
1325
1326         output(o, 1, _("CONFLICT (rename/rename): "
1327                "Rename %s->%s in %s. "
1328                "Rename %s->%s in %s"),
1329                a->path, c1->path, ci->branch1,
1330                b->path, c2->path, ci->branch2);
1331
1332         remove_file(o, 1, a->path, o->call_depth || would_lose_untracked(a->path));
1333         remove_file(o, 1, b->path, o->call_depth || would_lose_untracked(b->path));
1334
1335         if (merge_file_special_markers(o, a, c1, &ci->ren1_other,
1336                                        o->branch1, c1->path,
1337                                        o->branch2, ci->ren1_other.path, &mfi_c1) ||
1338             merge_file_special_markers(o, b, &ci->ren2_other, c2,
1339                                        o->branch1, ci->ren2_other.path,
1340                                        o->branch2, c2->path, &mfi_c2))
1341                 return -1;
1342
1343         if (o->call_depth) {
1344                 /*
1345                  * If mfi_c1.clean && mfi_c2.clean, then it might make
1346                  * sense to do a two-way merge of those results.  But, I
1347                  * think in all cases, it makes sense to have the virtual
1348                  * merge base just undo the renames; they can be detected
1349                  * again later for the non-recursive merge.
1350                  */
1351                 remove_file(o, 0, path, 0);
1352                 ret = update_file(o, 0, &mfi_c1.oid, mfi_c1.mode, a->path);
1353                 if (!ret)
1354                         ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
1355                                           b->path);
1356         } else {
1357                 char *new_path1 = unique_path(o, path, ci->branch1);
1358                 char *new_path2 = unique_path(o, path, ci->branch2);
1359                 output(o, 1, _("Renaming %s to %s and %s to %s instead"),
1360                        a->path, new_path1, b->path, new_path2);
1361                 remove_file(o, 0, path, 0);
1362                 ret = update_file(o, 0, &mfi_c1.oid, mfi_c1.mode, new_path1);
1363                 if (!ret)
1364                         ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
1365                                           new_path2);
1366                 free(new_path2);
1367                 free(new_path1);
1368         }
1369
1370         return ret;
1371 }
1372
1373 static int process_renames(struct merge_options *o,
1374                            struct string_list *a_renames,
1375                            struct string_list *b_renames)
1376 {
1377         int clean_merge = 1, i, j;
1378         struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
1379         struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
1380         const struct rename *sre;
1381
1382         for (i = 0; i < a_renames->nr; i++) {
1383                 sre = a_renames->items[i].util;
1384                 string_list_insert(&a_by_dst, sre->pair->two->path)->util
1385                         = (void *)sre;
1386         }
1387         for (i = 0; i < b_renames->nr; i++) {
1388                 sre = b_renames->items[i].util;
1389                 string_list_insert(&b_by_dst, sre->pair->two->path)->util
1390                         = (void *)sre;
1391         }
1392
1393         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1394                 struct string_list *renames1, *renames2Dst;
1395                 struct rename *ren1 = NULL, *ren2 = NULL;
1396                 const char *branch1, *branch2;
1397                 const char *ren1_src, *ren1_dst;
1398                 struct string_list_item *lookup;
1399
1400                 if (i >= a_renames->nr) {
1401                         ren2 = b_renames->items[j++].util;
1402                 } else if (j >= b_renames->nr) {
1403                         ren1 = a_renames->items[i++].util;
1404                 } else {
1405                         int compare = strcmp(a_renames->items[i].string,
1406                                              b_renames->items[j].string);
1407                         if (compare <= 0)
1408                                 ren1 = a_renames->items[i++].util;
1409                         if (compare >= 0)
1410                                 ren2 = b_renames->items[j++].util;
1411                 }
1412
1413                 /* TODO: refactor, so that 1/2 are not needed */
1414                 if (ren1) {
1415                         renames1 = a_renames;
1416                         renames2Dst = &b_by_dst;
1417                         branch1 = o->branch1;
1418                         branch2 = o->branch2;
1419                 } else {
1420                         renames1 = b_renames;
1421                         renames2Dst = &a_by_dst;
1422                         branch1 = o->branch2;
1423                         branch2 = o->branch1;
1424                         SWAP(ren2, ren1);
1425                 }
1426
1427                 if (ren1->processed)
1428                         continue;
1429                 ren1->processed = 1;
1430                 ren1->dst_entry->processed = 1;
1431                 /* BUG: We should only mark src_entry as processed if we
1432                  * are not dealing with a rename + add-source case.
1433                  */
1434                 ren1->src_entry->processed = 1;
1435
1436                 ren1_src = ren1->pair->one->path;
1437                 ren1_dst = ren1->pair->two->path;
1438
1439                 if (ren2) {
1440                         /* One file renamed on both sides */
1441                         const char *ren2_src = ren2->pair->one->path;
1442                         const char *ren2_dst = ren2->pair->two->path;
1443                         enum rename_type rename_type;
1444                         if (strcmp(ren1_src, ren2_src) != 0)
1445                                 die("BUG: ren1_src != ren2_src");
1446                         ren2->dst_entry->processed = 1;
1447                         ren2->processed = 1;
1448                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1449                                 rename_type = RENAME_ONE_FILE_TO_TWO;
1450                                 clean_merge = 0;
1451                         } else {
1452                                 rename_type = RENAME_ONE_FILE_TO_ONE;
1453                                 /* BUG: We should only remove ren1_src in
1454                                  * the base stage (think of rename +
1455                                  * add-source cases).
1456                                  */
1457                                 remove_file(o, 1, ren1_src, 1);
1458                                 update_entry(ren1->dst_entry,
1459                                              ren1->pair->one,
1460                                              ren1->pair->two,
1461                                              ren2->pair->two);
1462                         }
1463                         setup_rename_conflict_info(rename_type,
1464                                                    ren1->pair,
1465                                                    ren2->pair,
1466                                                    branch1,
1467                                                    branch2,
1468                                                    ren1->dst_entry,
1469                                                    ren2->dst_entry,
1470                                                    o,
1471                                                    NULL,
1472                                                    NULL);
1473                 } else if ((lookup = string_list_lookup(renames2Dst, ren1_dst))) {
1474                         /* Two different files renamed to the same thing */
1475                         char *ren2_dst;
1476                         ren2 = lookup->util;
1477                         ren2_dst = ren2->pair->two->path;
1478                         if (strcmp(ren1_dst, ren2_dst) != 0)
1479                                 die("BUG: ren1_dst != ren2_dst");
1480
1481                         clean_merge = 0;
1482                         ren2->processed = 1;
1483                         /*
1484                          * BUG: We should only mark src_entry as processed
1485                          * if we are not dealing with a rename + add-source
1486                          * case.
1487                          */
1488                         ren2->src_entry->processed = 1;
1489
1490                         setup_rename_conflict_info(RENAME_TWO_FILES_TO_ONE,
1491                                                    ren1->pair,
1492                                                    ren2->pair,
1493                                                    branch1,
1494                                                    branch2,
1495                                                    ren1->dst_entry,
1496                                                    ren2->dst_entry,
1497                                                    o,
1498                                                    ren1->src_entry,
1499                                                    ren2->src_entry);
1500
1501                 } else {
1502                         /* Renamed in 1, maybe changed in 2 */
1503                         /* we only use sha1 and mode of these */
1504                         struct diff_filespec src_other, dst_other;
1505                         int try_merge;
1506
1507                         /*
1508                          * unpack_trees loads entries from common-commit
1509                          * into stage 1, from head-commit into stage 2, and
1510                          * from merge-commit into stage 3.  We keep track
1511                          * of which side corresponds to the rename.
1512                          */
1513                         int renamed_stage = a_renames == renames1 ? 2 : 3;
1514                         int other_stage =   a_renames == renames1 ? 3 : 2;
1515
1516                         /* BUG: We should only remove ren1_src in the base
1517                          * stage and in other_stage (think of rename +
1518                          * add-source case).
1519                          */
1520                         remove_file(o, 1, ren1_src,
1521                                     renamed_stage == 2 || !was_tracked(ren1_src));
1522
1523                         oidcpy(&src_other.oid,
1524                                &ren1->src_entry->stages[other_stage].oid);
1525                         src_other.mode = ren1->src_entry->stages[other_stage].mode;
1526                         oidcpy(&dst_other.oid,
1527                                &ren1->dst_entry->stages[other_stage].oid);
1528                         dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
1529                         try_merge = 0;
1530
1531                         if (oid_eq(&src_other.oid, &null_oid)) {
1532                                 setup_rename_conflict_info(RENAME_DELETE,
1533                                                            ren1->pair,
1534                                                            NULL,
1535                                                            branch1,
1536                                                            branch2,
1537                                                            ren1->dst_entry,
1538                                                            NULL,
1539                                                            o,
1540                                                            NULL,
1541                                                            NULL);
1542                         } else if ((dst_other.mode == ren1->pair->two->mode) &&
1543                                    oid_eq(&dst_other.oid, &ren1->pair->two->oid)) {
1544                                 /*
1545                                  * Added file on the other side identical to
1546                                  * the file being renamed: clean merge.
1547                                  * Also, there is no need to overwrite the
1548                                  * file already in the working copy, so call
1549                                  * update_file_flags() instead of
1550                                  * update_file().
1551                                  */
1552                                 if (update_file_flags(o,
1553                                                       &ren1->pair->two->oid,
1554                                                       ren1->pair->two->mode,
1555                                                       ren1_dst,
1556                                                       1, /* update_cache */
1557                                                       0  /* update_wd    */))
1558                                         clean_merge = -1;
1559                         } else if (!oid_eq(&dst_other.oid, &null_oid)) {
1560                                 clean_merge = 0;
1561                                 try_merge = 1;
1562                                 output(o, 1, _("CONFLICT (rename/add): Rename %s->%s in %s. "
1563                                        "%s added in %s"),
1564                                        ren1_src, ren1_dst, branch1,
1565                                        ren1_dst, branch2);
1566                                 if (o->call_depth) {
1567                                         struct merge_file_info mfi;
1568                                         if (merge_file_one(o, ren1_dst, &null_oid, 0,
1569                                                            &ren1->pair->two->oid,
1570                                                            ren1->pair->two->mode,
1571                                                            &dst_other.oid,
1572                                                            dst_other.mode,
1573                                                            branch1, branch2, &mfi)) {
1574                                                 clean_merge = -1;
1575                                                 goto cleanup_and_return;
1576                                         }
1577                                         output(o, 1, _("Adding merged %s"), ren1_dst);
1578                                         if (update_file(o, 0, &mfi.oid,
1579                                                         mfi.mode, ren1_dst))
1580                                                 clean_merge = -1;
1581                                         try_merge = 0;
1582                                 } else {
1583                                         char *new_path = unique_path(o, ren1_dst, branch2);
1584                                         output(o, 1, _("Adding as %s instead"), new_path);
1585                                         if (update_file(o, 0, &dst_other.oid,
1586                                                         dst_other.mode, new_path))
1587                                                 clean_merge = -1;
1588                                         free(new_path);
1589                                 }
1590                         } else
1591                                 try_merge = 1;
1592
1593                         if (clean_merge < 0)
1594                                 goto cleanup_and_return;
1595                         if (try_merge) {
1596                                 struct diff_filespec *one, *a, *b;
1597                                 src_other.path = (char *)ren1_src;
1598
1599                                 one = ren1->pair->one;
1600                                 if (a_renames == renames1) {
1601                                         a = ren1->pair->two;
1602                                         b = &src_other;
1603                                 } else {
1604                                         b = ren1->pair->two;
1605                                         a = &src_other;
1606                                 }
1607                                 update_entry(ren1->dst_entry, one, a, b);
1608                                 setup_rename_conflict_info(RENAME_NORMAL,
1609                                                            ren1->pair,
1610                                                            NULL,
1611                                                            branch1,
1612                                                            NULL,
1613                                                            ren1->dst_entry,
1614                                                            NULL,
1615                                                            o,
1616                                                            NULL,
1617                                                            NULL);
1618                         }
1619                 }
1620         }
1621 cleanup_and_return:
1622         string_list_clear(&a_by_dst, 0);
1623         string_list_clear(&b_by_dst, 0);
1624
1625         return clean_merge;
1626 }
1627
1628 static struct object_id *stage_oid(const struct object_id *oid, unsigned mode)
1629 {
1630         return (is_null_oid(oid) || mode == 0) ? NULL: (struct object_id *)oid;
1631 }
1632
1633 static int read_oid_strbuf(struct merge_options *o,
1634         const struct object_id *oid, struct strbuf *dst)
1635 {
1636         void *buf;
1637         enum object_type type;
1638         unsigned long size;
1639         buf = read_sha1_file(oid->hash, &type, &size);
1640         if (!buf)
1641                 return err(o, _("cannot read object %s"), oid_to_hex(oid));
1642         if (type != OBJ_BLOB) {
1643                 free(buf);
1644                 return err(o, _("object %s is not a blob"), oid_to_hex(oid));
1645         }
1646         strbuf_attach(dst, buf, size, size + 1);
1647         return 0;
1648 }
1649
1650 static int blob_unchanged(struct merge_options *opt,
1651                           const struct object_id *o_oid,
1652                           unsigned o_mode,
1653                           const struct object_id *a_oid,
1654                           unsigned a_mode,
1655                           int renormalize, const char *path)
1656 {
1657         struct strbuf o = STRBUF_INIT;
1658         struct strbuf a = STRBUF_INIT;
1659         int ret = 0; /* assume changed for safety */
1660
1661         if (a_mode != o_mode)
1662                 return 0;
1663         if (oid_eq(o_oid, a_oid))
1664                 return 1;
1665         if (!renormalize)
1666                 return 0;
1667
1668         assert(o_oid && a_oid);
1669         if (read_oid_strbuf(opt, o_oid, &o) || read_oid_strbuf(opt, a_oid, &a))
1670                 goto error_return;
1671         /*
1672          * Note: binary | is used so that both renormalizations are
1673          * performed.  Comparison can be skipped if both files are
1674          * unchanged since their sha1s have already been compared.
1675          */
1676         if (renormalize_buffer(&the_index, path, o.buf, o.len, &o) |
1677             renormalize_buffer(&the_index, path, a.buf, a.len, &a))
1678                 ret = (o.len == a.len && !memcmp(o.buf, a.buf, o.len));
1679
1680 error_return:
1681         strbuf_release(&o);
1682         strbuf_release(&a);
1683         return ret;
1684 }
1685
1686 static int handle_modify_delete(struct merge_options *o,
1687                                  const char *path,
1688                                  struct object_id *o_oid, int o_mode,
1689                                  struct object_id *a_oid, int a_mode,
1690                                  struct object_id *b_oid, int b_mode)
1691 {
1692         const char *modify_branch, *delete_branch;
1693         struct object_id *changed_oid;
1694         int changed_mode;
1695
1696         if (a_oid) {
1697                 modify_branch = o->branch1;
1698                 delete_branch = o->branch2;
1699                 changed_oid = a_oid;
1700                 changed_mode = a_mode;
1701         } else {
1702                 modify_branch = o->branch2;
1703                 delete_branch = o->branch1;
1704                 changed_oid = b_oid;
1705                 changed_mode = b_mode;
1706         }
1707
1708         return handle_change_delete(o,
1709                                     path, NULL,
1710                                     o_oid, o_mode,
1711                                     changed_oid, changed_mode,
1712                                     modify_branch, delete_branch,
1713                                     _("modify"), _("modified"));
1714 }
1715
1716 static int merge_content(struct merge_options *o,
1717                          const char *path,
1718                          struct object_id *o_oid, int o_mode,
1719                          struct object_id *a_oid, int a_mode,
1720                          struct object_id *b_oid, int b_mode,
1721                          struct rename_conflict_info *rename_conflict_info)
1722 {
1723         const char *reason = _("content");
1724         const char *path1 = NULL, *path2 = NULL;
1725         struct merge_file_info mfi;
1726         struct diff_filespec one, a, b;
1727         unsigned df_conflict_remains = 0;
1728
1729         if (!o_oid) {
1730                 reason = _("add/add");
1731                 o_oid = (struct object_id *)&null_oid;
1732         }
1733         one.path = a.path = b.path = (char *)path;
1734         oidcpy(&one.oid, o_oid);
1735         one.mode = o_mode;
1736         oidcpy(&a.oid, a_oid);
1737         a.mode = a_mode;
1738         oidcpy(&b.oid, b_oid);
1739         b.mode = b_mode;
1740
1741         if (rename_conflict_info) {
1742                 struct diff_filepair *pair1 = rename_conflict_info->pair1;
1743
1744                 path1 = (o->branch1 == rename_conflict_info->branch1) ?
1745                         pair1->two->path : pair1->one->path;
1746                 /* If rename_conflict_info->pair2 != NULL, we are in
1747                  * RENAME_ONE_FILE_TO_ONE case.  Otherwise, we have a
1748                  * normal rename.
1749                  */
1750                 path2 = (rename_conflict_info->pair2 ||
1751                          o->branch2 == rename_conflict_info->branch1) ?
1752                         pair1->two->path : pair1->one->path;
1753
1754                 if (dir_in_way(path, !o->call_depth,
1755                                S_ISGITLINK(pair1->two->mode)))
1756                         df_conflict_remains = 1;
1757         }
1758         if (merge_file_special_markers(o, &one, &a, &b,
1759                                        o->branch1, path1,
1760                                        o->branch2, path2, &mfi))
1761                 return -1;
1762
1763         if (mfi.clean && !df_conflict_remains &&
1764             oid_eq(&mfi.oid, a_oid) && mfi.mode == a_mode) {
1765                 int path_renamed_outside_HEAD;
1766                 output(o, 3, _("Skipped %s (merged same as existing)"), path);
1767                 /*
1768                  * The content merge resulted in the same file contents we
1769                  * already had.  We can return early if those file contents
1770                  * are recorded at the correct path (which may not be true
1771                  * if the merge involves a rename).
1772                  */
1773                 path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
1774                 if (!path_renamed_outside_HEAD) {
1775                         add_cacheinfo(o, mfi.mode, &mfi.oid, path,
1776                                       0, (!o->call_depth), 0);
1777                         return mfi.clean;
1778                 }
1779         } else
1780                 output(o, 2, _("Auto-merging %s"), path);
1781
1782         if (!mfi.clean) {
1783                 if (S_ISGITLINK(mfi.mode))
1784                         reason = _("submodule");
1785                 output(o, 1, _("CONFLICT (%s): Merge conflict in %s"),
1786                                 reason, path);
1787                 if (rename_conflict_info && !df_conflict_remains)
1788                         if (update_stages(o, path, &one, &a, &b))
1789                                 return -1;
1790         }
1791
1792         if (df_conflict_remains) {
1793                 char *new_path;
1794                 if (o->call_depth) {
1795                         remove_file_from_cache(path);
1796                 } else {
1797                         if (!mfi.clean) {
1798                                 if (update_stages(o, path, &one, &a, &b))
1799                                         return -1;
1800                         } else {
1801                                 int file_from_stage2 = was_tracked(path);
1802                                 struct diff_filespec merged;
1803                                 oidcpy(&merged.oid, &mfi.oid);
1804                                 merged.mode = mfi.mode;
1805
1806                                 if (update_stages(o, path, NULL,
1807                                                   file_from_stage2 ? &merged : NULL,
1808                                                   file_from_stage2 ? NULL : &merged))
1809                                         return -1;
1810                         }
1811
1812                 }
1813                 new_path = unique_path(o, path, rename_conflict_info->branch1);
1814                 output(o, 1, _("Adding as %s instead"), new_path);
1815                 if (update_file(o, 0, &mfi.oid, mfi.mode, new_path)) {
1816                         free(new_path);
1817                         return -1;
1818                 }
1819                 free(new_path);
1820                 mfi.clean = 0;
1821         } else if (update_file(o, mfi.clean, &mfi.oid, mfi.mode, path))
1822                 return -1;
1823         return mfi.clean;
1824 }
1825
1826 /* Per entry merge function */
1827 static int process_entry(struct merge_options *o,
1828                          const char *path, struct stage_data *entry)
1829 {
1830         int clean_merge = 1;
1831         int normalize = o->renormalize;
1832         unsigned o_mode = entry->stages[1].mode;
1833         unsigned a_mode = entry->stages[2].mode;
1834         unsigned b_mode = entry->stages[3].mode;
1835         struct object_id *o_oid = stage_oid(&entry->stages[1].oid, o_mode);
1836         struct object_id *a_oid = stage_oid(&entry->stages[2].oid, a_mode);
1837         struct object_id *b_oid = stage_oid(&entry->stages[3].oid, b_mode);
1838
1839         entry->processed = 1;
1840         if (entry->rename_conflict_info) {
1841                 struct rename_conflict_info *conflict_info = entry->rename_conflict_info;
1842                 switch (conflict_info->rename_type) {
1843                 case RENAME_NORMAL:
1844                 case RENAME_ONE_FILE_TO_ONE:
1845                         clean_merge = merge_content(o, path,
1846                                                     o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
1847                                                     conflict_info);
1848                         break;
1849                 case RENAME_DELETE:
1850                         clean_merge = 0;
1851                         if (conflict_rename_delete(o,
1852                                                    conflict_info->pair1,
1853                                                    conflict_info->branch1,
1854                                                    conflict_info->branch2))
1855                                 clean_merge = -1;
1856                         break;
1857                 case RENAME_ONE_FILE_TO_TWO:
1858                         clean_merge = 0;
1859                         if (conflict_rename_rename_1to2(o, conflict_info))
1860                                 clean_merge = -1;
1861                         break;
1862                 case RENAME_TWO_FILES_TO_ONE:
1863                         clean_merge = 0;
1864                         if (conflict_rename_rename_2to1(o, conflict_info))
1865                                 clean_merge = -1;
1866                         break;
1867                 default:
1868                         entry->processed = 0;
1869                         break;
1870                 }
1871         } else if (o_oid && (!a_oid || !b_oid)) {
1872                 /* Case A: Deleted in one */
1873                 if ((!a_oid && !b_oid) ||
1874                     (!b_oid && blob_unchanged(o, o_oid, o_mode, a_oid, a_mode, normalize, path)) ||
1875                     (!a_oid && blob_unchanged(o, o_oid, o_mode, b_oid, b_mode, normalize, path))) {
1876                         /* Deleted in both or deleted in one and
1877                          * unchanged in the other */
1878                         if (a_oid)
1879                                 output(o, 2, _("Removing %s"), path);
1880                         /* do not touch working file if it did not exist */
1881                         remove_file(o, 1, path, !a_oid);
1882                 } else {
1883                         /* Modify/delete; deleted side may have put a directory in the way */
1884                         clean_merge = 0;
1885                         if (handle_modify_delete(o, path, o_oid, o_mode,
1886                                                  a_oid, a_mode, b_oid, b_mode))
1887                                 clean_merge = -1;
1888                 }
1889         } else if ((!o_oid && a_oid && !b_oid) ||
1890                    (!o_oid && !a_oid && b_oid)) {
1891                 /* Case B: Added in one. */
1892                 /* [nothing|directory] -> ([nothing|directory], file) */
1893
1894                 const char *add_branch;
1895                 const char *other_branch;
1896                 unsigned mode;
1897                 const struct object_id *oid;
1898                 const char *conf;
1899
1900                 if (a_oid) {
1901                         add_branch = o->branch1;
1902                         other_branch = o->branch2;
1903                         mode = a_mode;
1904                         oid = a_oid;
1905                         conf = _("file/directory");
1906                 } else {
1907                         add_branch = o->branch2;
1908                         other_branch = o->branch1;
1909                         mode = b_mode;
1910                         oid = b_oid;
1911                         conf = _("directory/file");
1912                 }
1913                 if (dir_in_way(path,
1914                                !o->call_depth && !S_ISGITLINK(a_mode),
1915                                0)) {
1916                         char *new_path = unique_path(o, path, add_branch);
1917                         clean_merge = 0;
1918                         output(o, 1, _("CONFLICT (%s): There is a directory with name %s in %s. "
1919                                "Adding %s as %s"),
1920                                conf, path, other_branch, path, new_path);
1921                         if (update_file(o, 0, oid, mode, new_path))
1922                                 clean_merge = -1;
1923                         else if (o->call_depth)
1924                                 remove_file_from_cache(path);
1925                         free(new_path);
1926                 } else {
1927                         output(o, 2, _("Adding %s"), path);
1928                         /* do not overwrite file if already present */
1929                         if (update_file_flags(o, oid, mode, path, 1, !a_oid))
1930                                 clean_merge = -1;
1931                 }
1932         } else if (a_oid && b_oid) {
1933                 /* Case C: Added in both (check for same permissions) and */
1934                 /* case D: Modified in both, but differently. */
1935                 clean_merge = merge_content(o, path,
1936                                             o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
1937                                             NULL);
1938         } else if (!o_oid && !a_oid && !b_oid) {
1939                 /*
1940                  * this entry was deleted altogether. a_mode == 0 means
1941                  * we had that path and want to actively remove it.
1942                  */
1943                 remove_file(o, 1, path, !a_mode);
1944         } else
1945                 die("BUG: fatal merge failure, shouldn't happen.");
1946
1947         return clean_merge;
1948 }
1949
1950 int merge_trees(struct merge_options *o,
1951                 struct tree *head,
1952                 struct tree *merge,
1953                 struct tree *common,
1954                 struct tree **result)
1955 {
1956         int code, clean;
1957
1958         if (o->subtree_shift) {
1959                 merge = shift_tree_object(head, merge, o->subtree_shift);
1960                 common = shift_tree_object(head, common, o->subtree_shift);
1961         }
1962
1963         if (oid_eq(&common->object.oid, &merge->object.oid)) {
1964                 struct strbuf sb = STRBUF_INIT;
1965
1966                 if (!o->call_depth && index_has_changes(&sb)) {
1967                         err(o, _("Dirty index: cannot merge (dirty: %s)"),
1968                             sb.buf);
1969                         return 0;
1970                 }
1971                 output(o, 0, _("Already up to date!"));
1972                 *result = head;
1973                 return 1;
1974         }
1975
1976         code = git_merge_trees(o->call_depth, common, head, merge);
1977
1978         if (code != 0) {
1979                 if (show(o, 4) || o->call_depth)
1980                         err(o, _("merging of trees %s and %s failed"),
1981                             oid_to_hex(&head->object.oid),
1982                             oid_to_hex(&merge->object.oid));
1983                 return -1;
1984         }
1985
1986         if (unmerged_cache()) {
1987                 struct string_list *entries, *re_head, *re_merge;
1988                 int i;
1989                 /*
1990                  * Only need the hashmap while processing entries, so
1991                  * initialize it here and free it when we are done running
1992                  * through the entries. Keeping it in the merge_options as
1993                  * opposed to decaring a local hashmap is for convenience
1994                  * so that we don't have to pass it to around.
1995                  */
1996                 hashmap_init(&o->current_file_dir_set, path_hashmap_cmp, NULL, 512);
1997                 get_files_dirs(o, head);
1998                 get_files_dirs(o, merge);
1999
2000                 entries = get_unmerged();
2001                 record_df_conflict_files(o, entries);
2002                 re_head  = get_renames(o, head, common, head, merge, entries);
2003                 re_merge = get_renames(o, merge, common, head, merge, entries);
2004                 clean = process_renames(o, re_head, re_merge);
2005                 if (clean < 0)
2006                         goto cleanup;
2007                 for (i = entries->nr-1; 0 <= i; i--) {
2008                         const char *path = entries->items[i].string;
2009                         struct stage_data *e = entries->items[i].util;
2010                         if (!e->processed) {
2011                                 int ret = process_entry(o, path, e);
2012                                 if (!ret)
2013                                         clean = 0;
2014                                 else if (ret < 0) {
2015                                         clean = ret;
2016                                         goto cleanup;
2017                                 }
2018                         }
2019                 }
2020                 for (i = 0; i < entries->nr; i++) {
2021                         struct stage_data *e = entries->items[i].util;
2022                         if (!e->processed)
2023                                 die("BUG: unprocessed path??? %s",
2024                                     entries->items[i].string);
2025                 }
2026
2027 cleanup:
2028                 string_list_clear(re_merge, 0);
2029                 string_list_clear(re_head, 0);
2030                 string_list_clear(entries, 1);
2031
2032                 hashmap_free(&o->current_file_dir_set, 1);
2033
2034                 free(re_merge);
2035                 free(re_head);
2036                 free(entries);
2037
2038                 if (clean < 0)
2039                         return clean;
2040         }
2041         else
2042                 clean = 1;
2043
2044         if (o->call_depth && !(*result = write_tree_from_memory(o)))
2045                 return -1;
2046
2047         return clean;
2048 }
2049
2050 static struct commit_list *reverse_commit_list(struct commit_list *list)
2051 {
2052         struct commit_list *next = NULL, *current, *backup;
2053         for (current = list; current; current = backup) {
2054                 backup = current->next;
2055                 current->next = next;
2056                 next = current;
2057         }
2058         return next;
2059 }
2060
2061 /*
2062  * Merge the commits h1 and h2, return the resulting virtual
2063  * commit object and a flag indicating the cleanness of the merge.
2064  */
2065 int merge_recursive(struct merge_options *o,
2066                     struct commit *h1,
2067                     struct commit *h2,
2068                     struct commit_list *ca,
2069                     struct commit **result)
2070 {
2071         struct commit_list *iter;
2072         struct commit *merged_common_ancestors;
2073         struct tree *mrtree = mrtree;
2074         int clean;
2075
2076         if (show(o, 4)) {
2077                 output(o, 4, _("Merging:"));
2078                 output_commit_title(o, h1);
2079                 output_commit_title(o, h2);
2080         }
2081
2082         if (!ca) {
2083                 ca = get_merge_bases(h1, h2);
2084                 ca = reverse_commit_list(ca);
2085         }
2086
2087         if (show(o, 5)) {
2088                 unsigned cnt = commit_list_count(ca);
2089
2090                 output(o, 5, Q_("found %u common ancestor:",
2091                                 "found %u common ancestors:", cnt), cnt);
2092                 for (iter = ca; iter; iter = iter->next)
2093                         output_commit_title(o, iter->item);
2094         }
2095
2096         merged_common_ancestors = pop_commit(&ca);
2097         if (merged_common_ancestors == NULL) {
2098                 /* if there is no common ancestor, use an empty tree */
2099                 struct tree *tree;
2100
2101                 tree = lookup_tree(the_hash_algo->empty_tree);
2102                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
2103         }
2104
2105         for (iter = ca; iter; iter = iter->next) {
2106                 const char *saved_b1, *saved_b2;
2107                 o->call_depth++;
2108                 /*
2109                  * When the merge fails, the result contains files
2110                  * with conflict markers. The cleanness flag is
2111                  * ignored (unless indicating an error), it was never
2112                  * actually used, as result of merge_trees has always
2113                  * overwritten it: the committed "conflicts" were
2114                  * already resolved.
2115                  */
2116                 discard_cache();
2117                 saved_b1 = o->branch1;
2118                 saved_b2 = o->branch2;
2119                 o->branch1 = "Temporary merge branch 1";
2120                 o->branch2 = "Temporary merge branch 2";
2121                 if (merge_recursive(o, merged_common_ancestors, iter->item,
2122                                     NULL, &merged_common_ancestors) < 0)
2123                         return -1;
2124                 o->branch1 = saved_b1;
2125                 o->branch2 = saved_b2;
2126                 o->call_depth--;
2127
2128                 if (!merged_common_ancestors)
2129                         return err(o, _("merge returned no commit"));
2130         }
2131
2132         discard_cache();
2133         if (!o->call_depth)
2134                 read_cache();
2135
2136         o->ancestor = "merged common ancestors";
2137         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
2138                             &mrtree);
2139         if (clean < 0) {
2140                 flush_output(o);
2141                 return clean;
2142         }
2143
2144         if (o->call_depth) {
2145                 *result = make_virtual_commit(mrtree, "merged tree");
2146                 commit_list_insert(h1, &(*result)->parents);
2147                 commit_list_insert(h2, &(*result)->parents->next);
2148         }
2149         flush_output(o);
2150         if (!o->call_depth && o->buffer_output < 2)
2151                 strbuf_release(&o->obuf);
2152         if (show(o, 2))
2153                 diff_warn_rename_limit("merge.renamelimit",
2154                                        o->needed_rename_limit, 0);
2155         return clean;
2156 }
2157
2158 static struct commit *get_ref(const struct object_id *oid, const char *name)
2159 {
2160         struct object *object;
2161
2162         object = deref_tag(parse_object(oid), name, strlen(name));
2163         if (!object)
2164                 return NULL;
2165         if (object->type == OBJ_TREE)
2166                 return make_virtual_commit((struct tree*)object, name);
2167         if (object->type != OBJ_COMMIT)
2168                 return NULL;
2169         if (parse_commit((struct commit *)object))
2170                 return NULL;
2171         return (struct commit *)object;
2172 }
2173
2174 int merge_recursive_generic(struct merge_options *o,
2175                             const struct object_id *head,
2176                             const struct object_id *merge,
2177                             int num_base_list,
2178                             const struct object_id **base_list,
2179                             struct commit **result)
2180 {
2181         int clean;
2182         struct lock_file lock = LOCK_INIT;
2183         struct commit *head_commit = get_ref(head, o->branch1);
2184         struct commit *next_commit = get_ref(merge, o->branch2);
2185         struct commit_list *ca = NULL;
2186
2187         if (base_list) {
2188                 int i;
2189                 for (i = 0; i < num_base_list; ++i) {
2190                         struct commit *base;
2191                         if (!(base = get_ref(base_list[i], oid_to_hex(base_list[i]))))
2192                                 return err(o, _("Could not parse object '%s'"),
2193                                         oid_to_hex(base_list[i]));
2194                         commit_list_insert(base, &ca);
2195                 }
2196         }
2197
2198         hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
2199         clean = merge_recursive(o, head_commit, next_commit, ca,
2200                         result);
2201         if (clean < 0)
2202                 return clean;
2203
2204         if (active_cache_changed &&
2205             write_locked_index(&the_index, &lock, COMMIT_LOCK))
2206                 return err(o, _("Unable to write index."));
2207
2208         return clean ? 0 : 1;
2209 }
2210
2211 static void merge_recursive_config(struct merge_options *o)
2212 {
2213         git_config_get_int("merge.verbosity", &o->verbosity);
2214         git_config_get_int("diff.renamelimit", &o->diff_rename_limit);
2215         git_config_get_int("merge.renamelimit", &o->merge_rename_limit);
2216         git_config(git_xmerge_config, NULL);
2217 }
2218
2219 void init_merge_options(struct merge_options *o)
2220 {
2221         const char *merge_verbosity;
2222         memset(o, 0, sizeof(struct merge_options));
2223         o->verbosity = 2;
2224         o->buffer_output = 1;
2225         o->diff_rename_limit = -1;
2226         o->merge_rename_limit = -1;
2227         o->renormalize = 0;
2228         o->detect_rename = 1;
2229         merge_recursive_config(o);
2230         merge_verbosity = getenv("GIT_MERGE_VERBOSITY");
2231         if (merge_verbosity)
2232                 o->verbosity = strtol(merge_verbosity, NULL, 10);
2233         if (o->verbosity >= 5)
2234                 o->buffer_output = 0;
2235         strbuf_init(&o->obuf, 0);
2236         string_list_init(&o->df_conflict_file_set, 1);
2237 }
2238
2239 int parse_merge_opt(struct merge_options *o, const char *s)
2240 {
2241         const char *arg;
2242
2243         if (!s || !*s)
2244                 return -1;
2245         if (!strcmp(s, "ours"))
2246                 o->recursive_variant = MERGE_RECURSIVE_OURS;
2247         else if (!strcmp(s, "theirs"))
2248                 o->recursive_variant = MERGE_RECURSIVE_THEIRS;
2249         else if (!strcmp(s, "subtree"))
2250                 o->subtree_shift = "";
2251         else if (skip_prefix(s, "subtree=", &arg))
2252                 o->subtree_shift = arg;
2253         else if (!strcmp(s, "patience"))
2254                 o->xdl_opts = DIFF_WITH_ALG(o, PATIENCE_DIFF);
2255         else if (!strcmp(s, "histogram"))
2256                 o->xdl_opts = DIFF_WITH_ALG(o, HISTOGRAM_DIFF);
2257         else if (skip_prefix(s, "diff-algorithm=", &arg)) {
2258                 long value = parse_algorithm_value(arg);
2259                 if (value < 0)
2260                         return -1;
2261                 /* clear out previous settings */
2262                 DIFF_XDL_CLR(o, NEED_MINIMAL);
2263                 o->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
2264                 o->xdl_opts |= value;
2265         }
2266         else if (!strcmp(s, "ignore-space-change"))
2267                 DIFF_XDL_SET(o, IGNORE_WHITESPACE_CHANGE);
2268         else if (!strcmp(s, "ignore-all-space"))
2269                 DIFF_XDL_SET(o, IGNORE_WHITESPACE);
2270         else if (!strcmp(s, "ignore-space-at-eol"))
2271                 DIFF_XDL_SET(o, IGNORE_WHITESPACE_AT_EOL);
2272         else if (!strcmp(s, "ignore-cr-at-eol"))
2273                 DIFF_XDL_SET(o, IGNORE_CR_AT_EOL);
2274         else if (!strcmp(s, "renormalize"))
2275                 o->renormalize = 1;
2276         else if (!strcmp(s, "no-renormalize"))
2277                 o->renormalize = 0;
2278         else if (!strcmp(s, "no-renames"))
2279                 o->detect_rename = 0;
2280         else if (!strcmp(s, "find-renames")) {
2281                 o->detect_rename = 1;
2282                 o->rename_score = 0;
2283         }
2284         else if (skip_prefix(s, "find-renames=", &arg) ||
2285                  skip_prefix(s, "rename-threshold=", &arg)) {
2286                 if ((o->rename_score = parse_rename_score(&arg)) == -1 || *arg != 0)
2287                         return -1;
2288                 o->detect_rename = 1;
2289         }
2290         else
2291                 return -1;
2292         return 0;
2293 }