serialize collection of refs that contain submodule changes
[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 "advice.h"
8 #include "lockfile.h"
9 #include "cache-tree.h"
10 #include "commit.h"
11 #include "blob.h"
12 #include "builtin.h"
13 #include "tree-walk.h"
14 #include "diff.h"
15 #include "diffcore.h"
16 #include "tag.h"
17 #include "unpack-trees.h"
18 #include "string-list.h"
19 #include "xdiff-interface.h"
20 #include "ll-merge.h"
21 #include "attr.h"
22 #include "merge-recursive.h"
23 #include "dir.h"
24 #include "submodule.h"
25
26 static void flush_output(struct merge_options *o)
27 {
28         if (o->buffer_output < 2 && o->obuf.len) {
29                 fputs(o->obuf.buf, stdout);
30                 strbuf_reset(&o->obuf);
31         }
32 }
33
34 static int err(struct merge_options *o, const char *err, ...)
35 {
36         va_list params;
37
38         if (o->buffer_output < 2)
39                 flush_output(o);
40         else {
41                 strbuf_complete(&o->obuf, '\n');
42                 strbuf_addstr(&o->obuf, "error: ");
43         }
44         va_start(params, err);
45         strbuf_vaddf(&o->obuf, err, params);
46         va_end(params);
47         if (o->buffer_output > 1)
48                 strbuf_addch(&o->obuf, '\n');
49         else {
50                 error("%s", o->obuf.buf);
51                 strbuf_reset(&o->obuf);
52         }
53
54         return -1;
55 }
56
57 static struct tree *shift_tree_object(struct tree *one, struct tree *two,
58                                       const char *subtree_shift)
59 {
60         struct object_id shifted;
61
62         if (!*subtree_shift) {
63                 shift_tree(&one->object.oid, &two->object.oid, &shifted, 0);
64         } else {
65                 shift_tree_by(&one->object.oid, &two->object.oid, &shifted,
66                               subtree_shift);
67         }
68         if (!oidcmp(&two->object.oid, &shifted))
69                 return two;
70         return lookup_tree(shifted.hash);
71 }
72
73 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
74 {
75         struct commit *commit = alloc_commit_node();
76
77         set_merge_remote_desc(commit, comment, (struct object *)commit);
78         commit->tree = tree;
79         commit->object.parsed = 1;
80         return commit;
81 }
82
83 /*
84  * Since we use get_tree_entry(), which does not put the read object into
85  * the object pool, we cannot rely on a == b.
86  */
87 static int oid_eq(const struct object_id *a, const struct object_id *b)
88 {
89         if (!a && !b)
90                 return 2;
91         return a && b && oidcmp(a, b) == 0;
92 }
93
94 enum rename_type {
95         RENAME_NORMAL = 0,
96         RENAME_DELETE,
97         RENAME_ONE_FILE_TO_ONE,
98         RENAME_ONE_FILE_TO_TWO,
99         RENAME_TWO_FILES_TO_ONE
100 };
101
102 struct rename_conflict_info {
103         enum rename_type rename_type;
104         struct diff_filepair *pair1;
105         struct diff_filepair *pair2;
106         const char *branch1;
107         const char *branch2;
108         struct stage_data *dst_entry1;
109         struct stage_data *dst_entry2;
110         struct diff_filespec ren1_other;
111         struct diff_filespec ren2_other;
112 };
113
114 /*
115  * Since we want to write the index eventually, we cannot reuse the index
116  * for these (temporary) data.
117  */
118 struct stage_data {
119         struct {
120                 unsigned mode;
121                 struct object_id oid;
122         } stages[4];
123         struct rename_conflict_info *rename_conflict_info;
124         unsigned processed:1;
125 };
126
127 static inline void setup_rename_conflict_info(enum rename_type rename_type,
128                                               struct diff_filepair *pair1,
129                                               struct diff_filepair *pair2,
130                                               const char *branch1,
131                                               const char *branch2,
132                                               struct stage_data *dst_entry1,
133                                               struct stage_data *dst_entry2,
134                                               struct merge_options *o,
135                                               struct stage_data *src_entry1,
136                                               struct stage_data *src_entry2)
137 {
138         struct rename_conflict_info *ci = xcalloc(1, sizeof(struct rename_conflict_info));
139         ci->rename_type = rename_type;
140         ci->pair1 = pair1;
141         ci->branch1 = branch1;
142         ci->branch2 = branch2;
143
144         ci->dst_entry1 = dst_entry1;
145         dst_entry1->rename_conflict_info = ci;
146         dst_entry1->processed = 0;
147
148         assert(!pair2 == !dst_entry2);
149         if (dst_entry2) {
150                 ci->dst_entry2 = dst_entry2;
151                 ci->pair2 = pair2;
152                 dst_entry2->rename_conflict_info = ci;
153         }
154
155         if (rename_type == RENAME_TWO_FILES_TO_ONE) {
156                 /*
157                  * For each rename, there could have been
158                  * modifications on the side of history where that
159                  * file was not renamed.
160                  */
161                 int ostage1 = o->branch1 == branch1 ? 3 : 2;
162                 int ostage2 = ostage1 ^ 1;
163
164                 ci->ren1_other.path = pair1->one->path;
165                 oidcpy(&ci->ren1_other.oid, &src_entry1->stages[ostage1].oid);
166                 ci->ren1_other.mode = src_entry1->stages[ostage1].mode;
167
168                 ci->ren2_other.path = pair2->one->path;
169                 oidcpy(&ci->ren2_other.oid, &src_entry2->stages[ostage2].oid);
170                 ci->ren2_other.mode = src_entry2->stages[ostage2].mode;
171         }
172 }
173
174 static int show(struct merge_options *o, int v)
175 {
176         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
177 }
178
179 __attribute__((format (printf, 3, 4)))
180 static void output(struct merge_options *o, int v, const char *fmt, ...)
181 {
182         va_list ap;
183
184         if (!show(o, v))
185                 return;
186
187         strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
188
189         va_start(ap, fmt);
190         strbuf_vaddf(&o->obuf, fmt, ap);
191         va_end(ap);
192
193         strbuf_addch(&o->obuf, '\n');
194         if (!o->buffer_output)
195                 flush_output(o);
196 }
197
198 static void output_commit_title(struct merge_options *o, struct commit *commit)
199 {
200         strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
201         if (commit->util)
202                 strbuf_addf(&o->obuf, "virtual %s\n",
203                         merge_remote_util(commit)->name);
204         else {
205                 strbuf_addf(&o->obuf, "%s ",
206                         find_unique_abbrev(commit->object.oid.hash,
207                                 DEFAULT_ABBREV));
208                 if (parse_commit(commit) != 0)
209                         strbuf_addstr(&o->obuf, _("(bad commit)\n"));
210                 else {
211                         const char *title;
212                         const char *msg = get_commit_buffer(commit, NULL);
213                         int len = find_commit_subject(msg, &title);
214                         if (len)
215                                 strbuf_addf(&o->obuf, "%.*s\n", len, title);
216                         unuse_commit_buffer(commit, msg);
217                 }
218         }
219         flush_output(o);
220 }
221
222 static int add_cacheinfo(struct merge_options *o,
223                 unsigned int mode, const struct object_id *oid,
224                 const char *path, int stage, int refresh, int options)
225 {
226         struct cache_entry *ce;
227         int ret;
228
229         ce = make_cache_entry(mode, oid ? oid->hash : null_sha1, path, stage, 0);
230         if (!ce)
231                 return err(o, _("addinfo_cache failed for path '%s'"), path);
232
233         ret = add_cache_entry(ce, options);
234         if (refresh) {
235                 struct cache_entry *nce;
236
237                 nce = refresh_cache_entry(ce, CE_MATCH_REFRESH | CE_MATCH_IGNORE_MISSING);
238                 if (nce != ce)
239                         ret = add_cache_entry(nce, options);
240         }
241         return ret;
242 }
243
244 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
245 {
246         parse_tree(tree);
247         init_tree_desc(desc, tree->buffer, tree->size);
248 }
249
250 static int git_merge_trees(int index_only,
251                            struct tree *common,
252                            struct tree *head,
253                            struct tree *merge)
254 {
255         int rc;
256         struct tree_desc t[3];
257         struct unpack_trees_options opts;
258
259         memset(&opts, 0, sizeof(opts));
260         if (index_only)
261                 opts.index_only = 1;
262         else
263                 opts.update = 1;
264         opts.merge = 1;
265         opts.head_idx = 2;
266         opts.fn = threeway_merge;
267         opts.src_index = &the_index;
268         opts.dst_index = &the_index;
269         setup_unpack_trees_porcelain(&opts, "merge");
270
271         init_tree_desc_from_tree(t+0, common);
272         init_tree_desc_from_tree(t+1, head);
273         init_tree_desc_from_tree(t+2, merge);
274
275         rc = unpack_trees(3, t, &opts);
276         cache_tree_free(&active_cache_tree);
277         return rc;
278 }
279
280 struct tree *write_tree_from_memory(struct merge_options *o)
281 {
282         struct tree *result = NULL;
283
284         if (unmerged_cache()) {
285                 int i;
286                 fprintf(stderr, "BUG: There are unmerged index entries:\n");
287                 for (i = 0; i < active_nr; i++) {
288                         const struct cache_entry *ce = active_cache[i];
289                         if (ce_stage(ce))
290                                 fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
291                                         (int)ce_namelen(ce), ce->name);
292                 }
293                 die("BUG: unmerged index entries in merge-recursive.c");
294         }
295
296         if (!active_cache_tree)
297                 active_cache_tree = cache_tree();
298
299         if (!cache_tree_fully_valid(active_cache_tree) &&
300             cache_tree_update(&the_index, 0) < 0) {
301                 err(o, _("error building trees"));
302                 return NULL;
303         }
304
305         result = lookup_tree(active_cache_tree->sha1);
306
307         return result;
308 }
309
310 static int save_files_dirs(const unsigned char *sha1,
311                 struct strbuf *base, const char *path,
312                 unsigned int mode, int stage, void *context)
313 {
314         int baselen = base->len;
315         struct merge_options *o = context;
316
317         strbuf_addstr(base, path);
318
319         if (S_ISDIR(mode))
320                 string_list_insert(&o->current_directory_set, base->buf);
321         else
322                 string_list_insert(&o->current_file_set, base->buf);
323
324         strbuf_setlen(base, baselen);
325         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
326 }
327
328 static int get_files_dirs(struct merge_options *o, struct tree *tree)
329 {
330         int n;
331         struct pathspec match_all;
332         memset(&match_all, 0, sizeof(match_all));
333         if (read_tree_recursive(tree, "", 0, 0, &match_all, save_files_dirs, o))
334                 return 0;
335         n = o->current_file_set.nr + o->current_directory_set.nr;
336         return n;
337 }
338
339 /*
340  * Returns an index_entry instance which doesn't have to correspond to
341  * a real cache entry in Git's index.
342  */
343 static struct stage_data *insert_stage_data(const char *path,
344                 struct tree *o, struct tree *a, struct tree *b,
345                 struct string_list *entries)
346 {
347         struct string_list_item *item;
348         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
349         get_tree_entry(o->object.oid.hash, path,
350                         e->stages[1].oid.hash, &e->stages[1].mode);
351         get_tree_entry(a->object.oid.hash, path,
352                         e->stages[2].oid.hash, &e->stages[2].mode);
353         get_tree_entry(b->object.oid.hash, path,
354                         e->stages[3].oid.hash, &e->stages[3].mode);
355         item = string_list_insert(entries, path);
356         item->util = e;
357         return e;
358 }
359
360 /*
361  * Create a dictionary mapping file names to stage_data objects. The
362  * dictionary contains one entry for every path with a non-zero stage entry.
363  */
364 static struct string_list *get_unmerged(void)
365 {
366         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
367         int i;
368
369         unmerged->strdup_strings = 1;
370
371         for (i = 0; i < active_nr; i++) {
372                 struct string_list_item *item;
373                 struct stage_data *e;
374                 const struct cache_entry *ce = active_cache[i];
375                 if (!ce_stage(ce))
376                         continue;
377
378                 item = string_list_lookup(unmerged, ce->name);
379                 if (!item) {
380                         item = string_list_insert(unmerged, ce->name);
381                         item->util = xcalloc(1, sizeof(struct stage_data));
382                 }
383                 e = item->util;
384                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
385                 oidcpy(&e->stages[ce_stage(ce)].oid, &ce->oid);
386         }
387
388         return unmerged;
389 }
390
391 static int string_list_df_name_compare(const void *a, const void *b)
392 {
393         const struct string_list_item *one = a;
394         const struct string_list_item *two = b;
395         int onelen = strlen(one->string);
396         int twolen = strlen(two->string);
397         /*
398          * Here we only care that entries for D/F conflicts are
399          * adjacent, in particular with the file of the D/F conflict
400          * appearing before files below the corresponding directory.
401          * The order of the rest of the list is irrelevant for us.
402          *
403          * To achieve this, we sort with df_name_compare and provide
404          * the mode S_IFDIR so that D/F conflicts will sort correctly.
405          * We use the mode S_IFDIR for everything else for simplicity,
406          * since in other cases any changes in their order due to
407          * sorting cause no problems for us.
408          */
409         int cmp = df_name_compare(one->string, onelen, S_IFDIR,
410                                   two->string, twolen, S_IFDIR);
411         /*
412          * Now that 'foo' and 'foo/bar' compare equal, we have to make sure
413          * that 'foo' comes before 'foo/bar'.
414          */
415         if (cmp)
416                 return cmp;
417         return onelen - twolen;
418 }
419
420 static void record_df_conflict_files(struct merge_options *o,
421                                      struct string_list *entries)
422 {
423         /* If there is a D/F conflict and the file for such a conflict
424          * currently exist in the working tree, we want to allow it to be
425          * removed to make room for the corresponding directory if needed.
426          * The files underneath the directories of such D/F conflicts will
427          * be processed before the corresponding file involved in the D/F
428          * conflict.  If the D/F directory ends up being removed by the
429          * merge, then we won't have to touch the D/F file.  If the D/F
430          * directory needs to be written to the working copy, then the D/F
431          * file will simply be removed (in make_room_for_path()) to make
432          * room for the necessary paths.  Note that if both the directory
433          * and the file need to be present, then the D/F file will be
434          * reinstated with a new unique name at the time it is processed.
435          */
436         struct string_list df_sorted_entries = STRING_LIST_INIT_NODUP;
437         const char *last_file = NULL;
438         int last_len = 0;
439         int i;
440
441         /*
442          * If we're merging merge-bases, we don't want to bother with
443          * any working directory changes.
444          */
445         if (o->call_depth)
446                 return;
447
448         /* Ensure D/F conflicts are adjacent in the entries list. */
449         for (i = 0; i < entries->nr; i++) {
450                 struct string_list_item *next = &entries->items[i];
451                 string_list_append(&df_sorted_entries, next->string)->util =
452                                    next->util;
453         }
454         qsort(df_sorted_entries.items, entries->nr, sizeof(*entries->items),
455               string_list_df_name_compare);
456
457         string_list_clear(&o->df_conflict_file_set, 1);
458         for (i = 0; i < df_sorted_entries.nr; i++) {
459                 const char *path = df_sorted_entries.items[i].string;
460                 int len = strlen(path);
461                 struct stage_data *e = df_sorted_entries.items[i].util;
462
463                 /*
464                  * Check if last_file & path correspond to a D/F conflict;
465                  * i.e. whether path is last_file+'/'+<something>.
466                  * If so, record that it's okay to remove last_file to make
467                  * room for path and friends if needed.
468                  */
469                 if (last_file &&
470                     len > last_len &&
471                     memcmp(path, last_file, last_len) == 0 &&
472                     path[last_len] == '/') {
473                         string_list_insert(&o->df_conflict_file_set, last_file);
474                 }
475
476                 /*
477                  * Determine whether path could exist as a file in the
478                  * working directory as a possible D/F conflict.  This
479                  * will only occur when it exists in stage 2 as a
480                  * file.
481                  */
482                 if (S_ISREG(e->stages[2].mode) || S_ISLNK(e->stages[2].mode)) {
483                         last_file = path;
484                         last_len = len;
485                 } else {
486                         last_file = NULL;
487                 }
488         }
489         string_list_clear(&df_sorted_entries, 0);
490 }
491
492 struct rename {
493         struct diff_filepair *pair;
494         struct stage_data *src_entry;
495         struct stage_data *dst_entry;
496         unsigned processed:1;
497 };
498
499 /*
500  * Get information of all renames which occurred between 'o_tree' and
501  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
502  * 'b_tree') to be able to associate the correct cache entries with
503  * the rename information. 'tree' is always equal to either a_tree or b_tree.
504  */
505 static struct string_list *get_renames(struct merge_options *o,
506                                        struct tree *tree,
507                                        struct tree *o_tree,
508                                        struct tree *a_tree,
509                                        struct tree *b_tree,
510                                        struct string_list *entries)
511 {
512         int i;
513         struct string_list *renames;
514         struct diff_options opts;
515
516         renames = xcalloc(1, sizeof(struct string_list));
517         if (!o->detect_rename)
518                 return renames;
519
520         diff_setup(&opts);
521         DIFF_OPT_SET(&opts, RECURSIVE);
522         DIFF_OPT_CLR(&opts, RENAME_EMPTY);
523         opts.detect_rename = DIFF_DETECT_RENAME;
524         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
525                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
526                             1000;
527         opts.rename_score = o->rename_score;
528         opts.show_rename_progress = o->show_rename_progress;
529         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
530         diff_setup_done(&opts);
531         diff_tree_sha1(o_tree->object.oid.hash, tree->object.oid.hash, "", &opts);
532         diffcore_std(&opts);
533         if (opts.needed_rename_limit > o->needed_rename_limit)
534                 o->needed_rename_limit = opts.needed_rename_limit;
535         for (i = 0; i < diff_queued_diff.nr; ++i) {
536                 struct string_list_item *item;
537                 struct rename *re;
538                 struct diff_filepair *pair = diff_queued_diff.queue[i];
539                 if (pair->status != 'R') {
540                         diff_free_filepair(pair);
541                         continue;
542                 }
543                 re = xmalloc(sizeof(*re));
544                 re->processed = 0;
545                 re->pair = pair;
546                 item = string_list_lookup(entries, re->pair->one->path);
547                 if (!item)
548                         re->src_entry = insert_stage_data(re->pair->one->path,
549                                         o_tree, a_tree, b_tree, entries);
550                 else
551                         re->src_entry = item->util;
552
553                 item = string_list_lookup(entries, re->pair->two->path);
554                 if (!item)
555                         re->dst_entry = insert_stage_data(re->pair->two->path,
556                                         o_tree, a_tree, b_tree, entries);
557                 else
558                         re->dst_entry = item->util;
559                 item = string_list_insert(renames, pair->one->path);
560                 item->util = re;
561         }
562         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
563         diff_queued_diff.nr = 0;
564         diff_flush(&opts);
565         return renames;
566 }
567
568 static int update_stages(struct merge_options *opt, const char *path,
569                          const struct diff_filespec *o,
570                          const struct diff_filespec *a,
571                          const struct diff_filespec *b)
572 {
573
574         /*
575          * NOTE: It is usually a bad idea to call update_stages on a path
576          * before calling update_file on that same path, since it can
577          * sometimes lead to spurious "refusing to lose untracked file..."
578          * messages from update_file (via make_room_for path via
579          * would_lose_untracked).  Instead, reverse the order of the calls
580          * (executing update_file first and then update_stages).
581          */
582         int clear = 1;
583         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_SKIP_DFCHECK;
584         if (clear)
585                 if (remove_file_from_cache(path))
586                         return -1;
587         if (o)
588                 if (add_cacheinfo(opt, o->mode, &o->oid, path, 1, 0, options))
589                         return -1;
590         if (a)
591                 if (add_cacheinfo(opt, a->mode, &a->oid, path, 2, 0, options))
592                         return -1;
593         if (b)
594                 if (add_cacheinfo(opt, b->mode, &b->oid, path, 3, 0, options))
595                         return -1;
596         return 0;
597 }
598
599 static void update_entry(struct stage_data *entry,
600                          struct diff_filespec *o,
601                          struct diff_filespec *a,
602                          struct diff_filespec *b)
603 {
604         entry->processed = 0;
605         entry->stages[1].mode = o->mode;
606         entry->stages[2].mode = a->mode;
607         entry->stages[3].mode = b->mode;
608         oidcpy(&entry->stages[1].oid, &o->oid);
609         oidcpy(&entry->stages[2].oid, &a->oid);
610         oidcpy(&entry->stages[3].oid, &b->oid);
611 }
612
613 static int remove_file(struct merge_options *o, int clean,
614                        const char *path, int no_wd)
615 {
616         int update_cache = o->call_depth || clean;
617         int update_working_directory = !o->call_depth && !no_wd;
618
619         if (update_cache) {
620                 if (remove_file_from_cache(path))
621                         return -1;
622         }
623         if (update_working_directory) {
624                 if (ignore_case) {
625                         struct cache_entry *ce;
626                         ce = cache_file_exists(path, strlen(path), ignore_case);
627                         if (ce && ce_stage(ce) == 0)
628                                 return 0;
629                 }
630                 if (remove_path(path))
631                         return -1;
632         }
633         return 0;
634 }
635
636 /* add a string to a strbuf, but converting "/" to "_" */
637 static void add_flattened_path(struct strbuf *out, const char *s)
638 {
639         size_t i = out->len;
640         strbuf_addstr(out, s);
641         for (; i < out->len; i++)
642                 if (out->buf[i] == '/')
643                         out->buf[i] = '_';
644 }
645
646 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
647 {
648         struct strbuf newpath = STRBUF_INIT;
649         int suffix = 0;
650         size_t base_len;
651
652         strbuf_addf(&newpath, "%s~", path);
653         add_flattened_path(&newpath, branch);
654
655         base_len = newpath.len;
656         while (string_list_has_string(&o->current_file_set, newpath.buf) ||
657                string_list_has_string(&o->current_directory_set, newpath.buf) ||
658                (!o->call_depth && file_exists(newpath.buf))) {
659                 strbuf_setlen(&newpath, base_len);
660                 strbuf_addf(&newpath, "_%d", suffix++);
661         }
662
663         string_list_insert(&o->current_file_set, newpath.buf);
664         return strbuf_detach(&newpath, NULL);
665 }
666
667 static int dir_in_way(const char *path, int check_working_copy)
668 {
669         int pos;
670         struct strbuf dirpath = STRBUF_INIT;
671         struct stat st;
672
673         strbuf_addstr(&dirpath, path);
674         strbuf_addch(&dirpath, '/');
675
676         pos = cache_name_pos(dirpath.buf, dirpath.len);
677
678         if (pos < 0)
679                 pos = -1 - pos;
680         if (pos < active_nr &&
681             !strncmp(dirpath.buf, active_cache[pos]->name, dirpath.len)) {
682                 strbuf_release(&dirpath);
683                 return 1;
684         }
685
686         strbuf_release(&dirpath);
687         return check_working_copy && !lstat(path, &st) && S_ISDIR(st.st_mode);
688 }
689
690 static int was_tracked(const char *path)
691 {
692         int pos = cache_name_pos(path, strlen(path));
693
694         if (0 <= pos)
695                 /* we have been tracking this path */
696                 return 1;
697
698         /*
699          * Look for an unmerged entry for the path,
700          * specifically stage #2, which would indicate
701          * that "our" side before the merge started
702          * had the path tracked (and resulted in a conflict).
703          */
704         for (pos = -1 - pos;
705              pos < active_nr && !strcmp(path, active_cache[pos]->name);
706              pos++)
707                 if (ce_stage(active_cache[pos]) == 2)
708                         return 1;
709         return 0;
710 }
711
712 static int would_lose_untracked(const char *path)
713 {
714         return !was_tracked(path) && file_exists(path);
715 }
716
717 static int make_room_for_path(struct merge_options *o, const char *path)
718 {
719         int status, i;
720         const char *msg = _("failed to create path '%s'%s");
721
722         /* Unlink any D/F conflict files that are in the way */
723         for (i = 0; i < o->df_conflict_file_set.nr; i++) {
724                 const char *df_path = o->df_conflict_file_set.items[i].string;
725                 size_t pathlen = strlen(path);
726                 size_t df_pathlen = strlen(df_path);
727                 if (df_pathlen < pathlen &&
728                     path[df_pathlen] == '/' &&
729                     strncmp(path, df_path, df_pathlen) == 0) {
730                         output(o, 3,
731                                _("Removing %s to make room for subdirectory\n"),
732                                df_path);
733                         unlink(df_path);
734                         unsorted_string_list_delete_item(&o->df_conflict_file_set,
735                                                          i, 0);
736                         break;
737                 }
738         }
739
740         /* Make sure leading directories are created */
741         status = safe_create_leading_directories_const(path);
742         if (status) {
743                 if (status == SCLD_EXISTS)
744                         /* something else exists */
745                         return err(o, msg, path, _(": perhaps a D/F conflict?"));
746                 return err(o, msg, path, "");
747         }
748
749         /*
750          * Do not unlink a file in the work tree if we are not
751          * tracking it.
752          */
753         if (would_lose_untracked(path))
754                 return err(o, _("refusing to lose untracked file at '%s'"),
755                              path);
756
757         /* Successful unlink is good.. */
758         if (!unlink(path))
759                 return 0;
760         /* .. and so is no existing file */
761         if (errno == ENOENT)
762                 return 0;
763         /* .. but not some other error (who really cares what?) */
764         return err(o, msg, path, _(": perhaps a D/F conflict?"));
765 }
766
767 static int update_file_flags(struct merge_options *o,
768                              const struct object_id *oid,
769                              unsigned mode,
770                              const char *path,
771                              int update_cache,
772                              int update_wd)
773 {
774         int ret = 0;
775
776         if (o->call_depth)
777                 update_wd = 0;
778
779         if (update_wd) {
780                 enum object_type type;
781                 void *buf;
782                 unsigned long size;
783
784                 if (S_ISGITLINK(mode)) {
785                         /*
786                          * We may later decide to recursively descend into
787                          * the submodule directory and update its index
788                          * and/or work tree, but we do not do that now.
789                          */
790                         update_wd = 0;
791                         goto update_index;
792                 }
793
794                 buf = read_sha1_file(oid->hash, &type, &size);
795                 if (!buf)
796                         return err(o, _("cannot read object %s '%s'"), oid_to_hex(oid), path);
797                 if (type != OBJ_BLOB) {
798                         ret = err(o, _("blob expected for %s '%s'"), oid_to_hex(oid), path);
799                         goto free_buf;
800                 }
801                 if (S_ISREG(mode)) {
802                         struct strbuf strbuf = STRBUF_INIT;
803                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
804                                 free(buf);
805                                 size = strbuf.len;
806                                 buf = strbuf_detach(&strbuf, NULL);
807                         }
808                 }
809
810                 if (make_room_for_path(o, path) < 0) {
811                         update_wd = 0;
812                         goto free_buf;
813                 }
814                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
815                         int fd;
816                         if (mode & 0100)
817                                 mode = 0777;
818                         else
819                                 mode = 0666;
820                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
821                         if (fd < 0) {
822                                 ret = err(o, _("failed to open '%s': %s"),
823                                           path, strerror(errno));
824                                 goto free_buf;
825                         }
826                         write_in_full(fd, buf, size);
827                         close(fd);
828                 } else if (S_ISLNK(mode)) {
829                         char *lnk = xmemdupz(buf, size);
830                         safe_create_leading_directories_const(path);
831                         unlink(path);
832                         if (symlink(lnk, path))
833                                 ret = err(o, _("failed to symlink '%s': %s"),
834                                         path, strerror(errno));
835                         free(lnk);
836                 } else
837                         ret = err(o,
838                                   _("do not know what to do with %06o %s '%s'"),
839                                   mode, oid_to_hex(oid), path);
840  free_buf:
841                 free(buf);
842         }
843  update_index:
844         if (!ret && update_cache)
845                 add_cacheinfo(o, mode, oid, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
846         return ret;
847 }
848
849 static int update_file(struct merge_options *o,
850                        int clean,
851                        const struct object_id *oid,
852                        unsigned mode,
853                        const char *path)
854 {
855         return update_file_flags(o, oid, mode, path, o->call_depth || clean, !o->call_depth);
856 }
857
858 /* Low level file merging, update and removal */
859
860 struct merge_file_info {
861         struct object_id oid;
862         unsigned mode;
863         unsigned clean:1,
864                  merge:1;
865 };
866
867 static int merge_3way(struct merge_options *o,
868                       mmbuffer_t *result_buf,
869                       const struct diff_filespec *one,
870                       const struct diff_filespec *a,
871                       const struct diff_filespec *b,
872                       const char *branch1,
873                       const char *branch2)
874 {
875         mmfile_t orig, src1, src2;
876         struct ll_merge_options ll_opts = {0};
877         char *base_name, *name1, *name2;
878         int merge_status;
879
880         ll_opts.renormalize = o->renormalize;
881         ll_opts.xdl_opts = o->xdl_opts;
882
883         if (o->call_depth) {
884                 ll_opts.virtual_ancestor = 1;
885                 ll_opts.variant = 0;
886         } else {
887                 switch (o->recursive_variant) {
888                 case MERGE_RECURSIVE_OURS:
889                         ll_opts.variant = XDL_MERGE_FAVOR_OURS;
890                         break;
891                 case MERGE_RECURSIVE_THEIRS:
892                         ll_opts.variant = XDL_MERGE_FAVOR_THEIRS;
893                         break;
894                 default:
895                         ll_opts.variant = 0;
896                         break;
897                 }
898         }
899
900         if (strcmp(a->path, b->path) ||
901             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
902                 base_name = o->ancestor == NULL ? NULL :
903                         mkpathdup("%s:%s", o->ancestor, one->path);
904                 name1 = mkpathdup("%s:%s", branch1, a->path);
905                 name2 = mkpathdup("%s:%s", branch2, b->path);
906         } else {
907                 base_name = o->ancestor == NULL ? NULL :
908                         mkpathdup("%s", o->ancestor);
909                 name1 = mkpathdup("%s", branch1);
910                 name2 = mkpathdup("%s", branch2);
911         }
912
913         read_mmblob(&orig, &one->oid);
914         read_mmblob(&src1, &a->oid);
915         read_mmblob(&src2, &b->oid);
916
917         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
918                                 &src1, name1, &src2, name2, &ll_opts);
919
920         free(base_name);
921         free(name1);
922         free(name2);
923         free(orig.ptr);
924         free(src1.ptr);
925         free(src2.ptr);
926         return merge_status;
927 }
928
929 static int merge_file_1(struct merge_options *o,
930                                            const struct diff_filespec *one,
931                                            const struct diff_filespec *a,
932                                            const struct diff_filespec *b,
933                                            const char *branch1,
934                                            const char *branch2,
935                                            struct merge_file_info *result)
936 {
937         result->merge = 0;
938         result->clean = 1;
939
940         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
941                 result->clean = 0;
942                 if (S_ISREG(a->mode)) {
943                         result->mode = a->mode;
944                         oidcpy(&result->oid, &a->oid);
945                 } else {
946                         result->mode = b->mode;
947                         oidcpy(&result->oid, &b->oid);
948                 }
949         } else {
950                 if (!oid_eq(&a->oid, &one->oid) && !oid_eq(&b->oid, &one->oid))
951                         result->merge = 1;
952
953                 /*
954                  * Merge modes
955                  */
956                 if (a->mode == b->mode || a->mode == one->mode)
957                         result->mode = b->mode;
958                 else {
959                         result->mode = a->mode;
960                         if (b->mode != one->mode) {
961                                 result->clean = 0;
962                                 result->merge = 1;
963                         }
964                 }
965
966                 if (oid_eq(&a->oid, &b->oid) || oid_eq(&a->oid, &one->oid))
967                         oidcpy(&result->oid, &b->oid);
968                 else if (oid_eq(&b->oid, &one->oid))
969                         oidcpy(&result->oid, &a->oid);
970                 else if (S_ISREG(a->mode)) {
971                         mmbuffer_t result_buf;
972                         int ret = 0, merge_status;
973
974                         merge_status = merge_3way(o, &result_buf, one, a, b,
975                                                   branch1, branch2);
976
977                         if ((merge_status < 0) || !result_buf.ptr)
978                                 ret = err(o, _("Failed to execute internal merge"));
979
980                         if (!ret && write_sha1_file(result_buf.ptr, result_buf.size,
981                                                     blob_type, result->oid.hash))
982                                 ret = err(o, _("Unable to add %s to database"),
983                                           a->path);
984
985                         free(result_buf.ptr);
986                         if (ret)
987                                 return ret;
988                         result->clean = (merge_status == 0);
989                 } else if (S_ISGITLINK(a->mode)) {
990                         result->clean = merge_submodule(result->oid.hash,
991                                                        one->path,
992                                                        one->oid.hash,
993                                                        a->oid.hash,
994                                                        b->oid.hash,
995                                                        !o->call_depth);
996                 } else if (S_ISLNK(a->mode)) {
997                         oidcpy(&result->oid, &a->oid);
998
999                         if (!oid_eq(&a->oid, &b->oid))
1000                                 result->clean = 0;
1001                 } else
1002                         die("BUG: unsupported object type in the tree");
1003         }
1004
1005         return 0;
1006 }
1007
1008 static int merge_file_special_markers(struct merge_options *o,
1009                            const struct diff_filespec *one,
1010                            const struct diff_filespec *a,
1011                            const struct diff_filespec *b,
1012                            const char *branch1,
1013                            const char *filename1,
1014                            const char *branch2,
1015                            const char *filename2,
1016                            struct merge_file_info *mfi)
1017 {
1018         char *side1 = NULL;
1019         char *side2 = NULL;
1020         int ret;
1021
1022         if (filename1)
1023                 side1 = xstrfmt("%s:%s", branch1, filename1);
1024         if (filename2)
1025                 side2 = xstrfmt("%s:%s", branch2, filename2);
1026
1027         ret = merge_file_1(o, one, a, b,
1028                            side1 ? side1 : branch1,
1029                            side2 ? side2 : branch2, mfi);
1030         free(side1);
1031         free(side2);
1032         return ret;
1033 }
1034
1035 static int merge_file_one(struct merge_options *o,
1036                                          const char *path,
1037                                          const struct object_id *o_oid, int o_mode,
1038                                          const struct object_id *a_oid, int a_mode,
1039                                          const struct object_id *b_oid, int b_mode,
1040                                          const char *branch1,
1041                                          const char *branch2,
1042                                          struct merge_file_info *mfi)
1043 {
1044         struct diff_filespec one, a, b;
1045
1046         one.path = a.path = b.path = (char *)path;
1047         oidcpy(&one.oid, o_oid);
1048         one.mode = o_mode;
1049         oidcpy(&a.oid, a_oid);
1050         a.mode = a_mode;
1051         oidcpy(&b.oid, b_oid);
1052         b.mode = b_mode;
1053         return merge_file_1(o, &one, &a, &b, branch1, branch2, mfi);
1054 }
1055
1056 static int handle_change_delete(struct merge_options *o,
1057                                  const char *path,
1058                                  const struct object_id *o_oid, int o_mode,
1059                                  const struct object_id *a_oid, int a_mode,
1060                                  const struct object_id *b_oid, int b_mode,
1061                                  const char *change, const char *change_past)
1062 {
1063         char *renamed = NULL;
1064         int ret = 0;
1065         if (dir_in_way(path, !o->call_depth)) {
1066                 renamed = unique_path(o, path, a_oid ? o->branch1 : o->branch2);
1067         }
1068
1069         if (o->call_depth) {
1070                 /*
1071                  * We cannot arbitrarily accept either a_sha or b_sha as
1072                  * correct; since there is no true "middle point" between
1073                  * them, simply reuse the base version for virtual merge base.
1074                  */
1075                 ret = remove_file_from_cache(path);
1076                 if (!ret)
1077                         ret = update_file(o, 0, o_oid, o_mode,
1078                                           renamed ? renamed : path);
1079         } else if (!a_oid) {
1080                 if (!renamed) {
1081                         output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1082                                "and %s in %s. Version %s of %s left in tree."),
1083                                change, path, o->branch1, change_past,
1084                                o->branch2, o->branch2, path);
1085                         ret = update_file(o, 0, b_oid, b_mode, path);
1086                 } else {
1087                         output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1088                                "and %s in %s. Version %s of %s left in tree at %s."),
1089                                change, path, o->branch1, change_past,
1090                                o->branch2, o->branch2, path, renamed);
1091                         ret = update_file(o, 0, b_oid, b_mode, renamed);
1092                 }
1093         } else {
1094                 if (!renamed) {
1095                         output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1096                                "and %s in %s. Version %s of %s left in tree."),
1097                                change, path, o->branch2, change_past,
1098                                o->branch1, o->branch1, path);
1099                 } else {
1100                         output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1101                                "and %s in %s. Version %s of %s left in tree at %s."),
1102                                change, path, o->branch2, change_past,
1103                                o->branch1, o->branch1, path, renamed);
1104                         ret = update_file(o, 0, a_oid, a_mode, renamed);
1105                 }
1106                 /*
1107                  * No need to call update_file() on path when !renamed, since
1108                  * that would needlessly touch path.  We could call
1109                  * update_file_flags() with update_cache=0 and update_wd=0,
1110                  * but that's a no-op.
1111                  */
1112         }
1113         free(renamed);
1114
1115         return ret;
1116 }
1117
1118 static int conflict_rename_delete(struct merge_options *o,
1119                                    struct diff_filepair *pair,
1120                                    const char *rename_branch,
1121                                    const char *other_branch)
1122 {
1123         const struct diff_filespec *orig = pair->one;
1124         const struct diff_filespec *dest = pair->two;
1125         const struct object_id *a_oid = NULL;
1126         const struct object_id *b_oid = NULL;
1127         int a_mode = 0;
1128         int b_mode = 0;
1129
1130         if (rename_branch == o->branch1) {
1131                 a_oid = &dest->oid;
1132                 a_mode = dest->mode;
1133         } else {
1134                 b_oid = &dest->oid;
1135                 b_mode = dest->mode;
1136         }
1137
1138         if (handle_change_delete(o,
1139                                  o->call_depth ? orig->path : dest->path,
1140                                  &orig->oid, orig->mode,
1141                                  a_oid, a_mode,
1142                                  b_oid, b_mode,
1143                                  _("rename"), _("renamed")))
1144                 return -1;
1145
1146         if (o->call_depth)
1147                 return remove_file_from_cache(dest->path);
1148         else
1149                 return update_stages(o, dest->path, NULL,
1150                                      rename_branch == o->branch1 ? dest : NULL,
1151                                      rename_branch == o->branch1 ? NULL : dest);
1152 }
1153
1154 static struct diff_filespec *filespec_from_entry(struct diff_filespec *target,
1155                                                  struct stage_data *entry,
1156                                                  int stage)
1157 {
1158         struct object_id *oid = &entry->stages[stage].oid;
1159         unsigned mode = entry->stages[stage].mode;
1160         if (mode == 0 || is_null_oid(oid))
1161                 return NULL;
1162         oidcpy(&target->oid, oid);
1163         target->mode = mode;
1164         return target;
1165 }
1166
1167 static int handle_file(struct merge_options *o,
1168                         struct diff_filespec *rename,
1169                         int stage,
1170                         struct rename_conflict_info *ci)
1171 {
1172         char *dst_name = rename->path;
1173         struct stage_data *dst_entry;
1174         const char *cur_branch, *other_branch;
1175         struct diff_filespec other;
1176         struct diff_filespec *add;
1177         int ret;
1178
1179         if (stage == 2) {
1180                 dst_entry = ci->dst_entry1;
1181                 cur_branch = ci->branch1;
1182                 other_branch = ci->branch2;
1183         } else {
1184                 dst_entry = ci->dst_entry2;
1185                 cur_branch = ci->branch2;
1186                 other_branch = ci->branch1;
1187         }
1188
1189         add = filespec_from_entry(&other, dst_entry, stage ^ 1);
1190         if (add) {
1191                 char *add_name = unique_path(o, rename->path, other_branch);
1192                 if (update_file(o, 0, &add->oid, add->mode, add_name))
1193                         return -1;
1194
1195                 remove_file(o, 0, rename->path, 0);
1196                 dst_name = unique_path(o, rename->path, cur_branch);
1197         } else {
1198                 if (dir_in_way(rename->path, !o->call_depth)) {
1199                         dst_name = unique_path(o, rename->path, cur_branch);
1200                         output(o, 1, _("%s is a directory in %s adding as %s instead"),
1201                                rename->path, other_branch, dst_name);
1202                 }
1203         }
1204         if ((ret = update_file(o, 0, &rename->oid, rename->mode, dst_name)))
1205                 ; /* fall through, do allow dst_name to be released */
1206         else if (stage == 2)
1207                 ret = update_stages(o, rename->path, NULL, rename, add);
1208         else
1209                 ret = update_stages(o, rename->path, NULL, add, rename);
1210
1211         if (dst_name != rename->path)
1212                 free(dst_name);
1213
1214         return ret;
1215 }
1216
1217 static int conflict_rename_rename_1to2(struct merge_options *o,
1218                                         struct rename_conflict_info *ci)
1219 {
1220         /* One file was renamed in both branches, but to different names. */
1221         struct diff_filespec *one = ci->pair1->one;
1222         struct diff_filespec *a = ci->pair1->two;
1223         struct diff_filespec *b = ci->pair2->two;
1224
1225         output(o, 1, _("CONFLICT (rename/rename): "
1226                "Rename \"%s\"->\"%s\" in branch \"%s\" "
1227                "rename \"%s\"->\"%s\" in \"%s\"%s"),
1228                one->path, a->path, ci->branch1,
1229                one->path, b->path, ci->branch2,
1230                o->call_depth ? _(" (left unresolved)") : "");
1231         if (o->call_depth) {
1232                 struct merge_file_info mfi;
1233                 struct diff_filespec other;
1234                 struct diff_filespec *add;
1235                 if (merge_file_one(o, one->path,
1236                                  &one->oid, one->mode,
1237                                  &a->oid, a->mode,
1238                                  &b->oid, b->mode,
1239                                  ci->branch1, ci->branch2, &mfi))
1240                         return -1;
1241
1242                 /*
1243                  * FIXME: For rename/add-source conflicts (if we could detect
1244                  * such), this is wrong.  We should instead find a unique
1245                  * pathname and then either rename the add-source file to that
1246                  * unique path, or use that unique path instead of src here.
1247                  */
1248                 if (update_file(o, 0, &mfi.oid, mfi.mode, one->path))
1249                         return -1;
1250
1251                 /*
1252                  * Above, we put the merged content at the merge-base's
1253                  * path.  Now we usually need to delete both a->path and
1254                  * b->path.  However, the rename on each side of the merge
1255                  * could also be involved in a rename/add conflict.  In
1256                  * such cases, we should keep the added file around,
1257                  * resolving the conflict at that path in its favor.
1258                  */
1259                 add = filespec_from_entry(&other, ci->dst_entry1, 2 ^ 1);
1260                 if (add) {
1261                         if (update_file(o, 0, &add->oid, add->mode, a->path))
1262                                 return -1;
1263                 }
1264                 else
1265                         remove_file_from_cache(a->path);
1266                 add = filespec_from_entry(&other, ci->dst_entry2, 3 ^ 1);
1267                 if (add) {
1268                         if (update_file(o, 0, &add->oid, add->mode, b->path))
1269                                 return -1;
1270                 }
1271                 else
1272                         remove_file_from_cache(b->path);
1273         } else if (handle_file(o, a, 2, ci) || handle_file(o, b, 3, ci))
1274                 return -1;
1275
1276         return 0;
1277 }
1278
1279 static int conflict_rename_rename_2to1(struct merge_options *o,
1280                                         struct rename_conflict_info *ci)
1281 {
1282         /* Two files, a & b, were renamed to the same thing, c. */
1283         struct diff_filespec *a = ci->pair1->one;
1284         struct diff_filespec *b = ci->pair2->one;
1285         struct diff_filespec *c1 = ci->pair1->two;
1286         struct diff_filespec *c2 = ci->pair2->two;
1287         char *path = c1->path; /* == c2->path */
1288         struct merge_file_info mfi_c1;
1289         struct merge_file_info mfi_c2;
1290         int ret;
1291
1292         output(o, 1, _("CONFLICT (rename/rename): "
1293                "Rename %s->%s in %s. "
1294                "Rename %s->%s in %s"),
1295                a->path, c1->path, ci->branch1,
1296                b->path, c2->path, ci->branch2);
1297
1298         remove_file(o, 1, a->path, o->call_depth || would_lose_untracked(a->path));
1299         remove_file(o, 1, b->path, o->call_depth || would_lose_untracked(b->path));
1300
1301         if (merge_file_special_markers(o, a, c1, &ci->ren1_other,
1302                                        o->branch1, c1->path,
1303                                        o->branch2, ci->ren1_other.path, &mfi_c1) ||
1304             merge_file_special_markers(o, b, &ci->ren2_other, c2,
1305                                        o->branch1, ci->ren2_other.path,
1306                                        o->branch2, c2->path, &mfi_c2))
1307                 return -1;
1308
1309         if (o->call_depth) {
1310                 /*
1311                  * If mfi_c1.clean && mfi_c2.clean, then it might make
1312                  * sense to do a two-way merge of those results.  But, I
1313                  * think in all cases, it makes sense to have the virtual
1314                  * merge base just undo the renames; they can be detected
1315                  * again later for the non-recursive merge.
1316                  */
1317                 remove_file(o, 0, path, 0);
1318                 ret = update_file(o, 0, &mfi_c1.oid, mfi_c1.mode, a->path);
1319                 if (!ret)
1320                         ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
1321                                           b->path);
1322         } else {
1323                 char *new_path1 = unique_path(o, path, ci->branch1);
1324                 char *new_path2 = unique_path(o, path, ci->branch2);
1325                 output(o, 1, _("Renaming %s to %s and %s to %s instead"),
1326                        a->path, new_path1, b->path, new_path2);
1327                 remove_file(o, 0, path, 0);
1328                 ret = update_file(o, 0, &mfi_c1.oid, mfi_c1.mode, new_path1);
1329                 if (!ret)
1330                         ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
1331                                           new_path2);
1332                 free(new_path2);
1333                 free(new_path1);
1334         }
1335
1336         return ret;
1337 }
1338
1339 static int process_renames(struct merge_options *o,
1340                            struct string_list *a_renames,
1341                            struct string_list *b_renames)
1342 {
1343         int clean_merge = 1, i, j;
1344         struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
1345         struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
1346         const struct rename *sre;
1347
1348         for (i = 0; i < a_renames->nr; i++) {
1349                 sre = a_renames->items[i].util;
1350                 string_list_insert(&a_by_dst, sre->pair->two->path)->util
1351                         = (void *)sre;
1352         }
1353         for (i = 0; i < b_renames->nr; i++) {
1354                 sre = b_renames->items[i].util;
1355                 string_list_insert(&b_by_dst, sre->pair->two->path)->util
1356                         = (void *)sre;
1357         }
1358
1359         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1360                 struct string_list *renames1, *renames2Dst;
1361                 struct rename *ren1 = NULL, *ren2 = NULL;
1362                 const char *branch1, *branch2;
1363                 const char *ren1_src, *ren1_dst;
1364                 struct string_list_item *lookup;
1365
1366                 if (i >= a_renames->nr) {
1367                         ren2 = b_renames->items[j++].util;
1368                 } else if (j >= b_renames->nr) {
1369                         ren1 = a_renames->items[i++].util;
1370                 } else {
1371                         int compare = strcmp(a_renames->items[i].string,
1372                                              b_renames->items[j].string);
1373                         if (compare <= 0)
1374                                 ren1 = a_renames->items[i++].util;
1375                         if (compare >= 0)
1376                                 ren2 = b_renames->items[j++].util;
1377                 }
1378
1379                 /* TODO: refactor, so that 1/2 are not needed */
1380                 if (ren1) {
1381                         renames1 = a_renames;
1382                         renames2Dst = &b_by_dst;
1383                         branch1 = o->branch1;
1384                         branch2 = o->branch2;
1385                 } else {
1386                         struct rename *tmp;
1387                         renames1 = b_renames;
1388                         renames2Dst = &a_by_dst;
1389                         branch1 = o->branch2;
1390                         branch2 = o->branch1;
1391                         tmp = ren2;
1392                         ren2 = ren1;
1393                         ren1 = tmp;
1394                 }
1395
1396                 if (ren1->processed)
1397                         continue;
1398                 ren1->processed = 1;
1399                 ren1->dst_entry->processed = 1;
1400                 /* BUG: We should only mark src_entry as processed if we
1401                  * are not dealing with a rename + add-source case.
1402                  */
1403                 ren1->src_entry->processed = 1;
1404
1405                 ren1_src = ren1->pair->one->path;
1406                 ren1_dst = ren1->pair->two->path;
1407
1408                 if (ren2) {
1409                         /* One file renamed on both sides */
1410                         const char *ren2_src = ren2->pair->one->path;
1411                         const char *ren2_dst = ren2->pair->two->path;
1412                         enum rename_type rename_type;
1413                         if (strcmp(ren1_src, ren2_src) != 0)
1414                                 die("BUG: ren1_src != ren2_src");
1415                         ren2->dst_entry->processed = 1;
1416                         ren2->processed = 1;
1417                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1418                                 rename_type = RENAME_ONE_FILE_TO_TWO;
1419                                 clean_merge = 0;
1420                         } else {
1421                                 rename_type = RENAME_ONE_FILE_TO_ONE;
1422                                 /* BUG: We should only remove ren1_src in
1423                                  * the base stage (think of rename +
1424                                  * add-source cases).
1425                                  */
1426                                 remove_file(o, 1, ren1_src, 1);
1427                                 update_entry(ren1->dst_entry,
1428                                              ren1->pair->one,
1429                                              ren1->pair->two,
1430                                              ren2->pair->two);
1431                         }
1432                         setup_rename_conflict_info(rename_type,
1433                                                    ren1->pair,
1434                                                    ren2->pair,
1435                                                    branch1,
1436                                                    branch2,
1437                                                    ren1->dst_entry,
1438                                                    ren2->dst_entry,
1439                                                    o,
1440                                                    NULL,
1441                                                    NULL);
1442                 } else if ((lookup = string_list_lookup(renames2Dst, ren1_dst))) {
1443                         /* Two different files renamed to the same thing */
1444                         char *ren2_dst;
1445                         ren2 = lookup->util;
1446                         ren2_dst = ren2->pair->two->path;
1447                         if (strcmp(ren1_dst, ren2_dst) != 0)
1448                                 die("BUG: ren1_dst != ren2_dst");
1449
1450                         clean_merge = 0;
1451                         ren2->processed = 1;
1452                         /*
1453                          * BUG: We should only mark src_entry as processed
1454                          * if we are not dealing with a rename + add-source
1455                          * case.
1456                          */
1457                         ren2->src_entry->processed = 1;
1458
1459                         setup_rename_conflict_info(RENAME_TWO_FILES_TO_ONE,
1460                                                    ren1->pair,
1461                                                    ren2->pair,
1462                                                    branch1,
1463                                                    branch2,
1464                                                    ren1->dst_entry,
1465                                                    ren2->dst_entry,
1466                                                    o,
1467                                                    ren1->src_entry,
1468                                                    ren2->src_entry);
1469
1470                 } else {
1471                         /* Renamed in 1, maybe changed in 2 */
1472                         /* we only use sha1 and mode of these */
1473                         struct diff_filespec src_other, dst_other;
1474                         int try_merge;
1475
1476                         /*
1477                          * unpack_trees loads entries from common-commit
1478                          * into stage 1, from head-commit into stage 2, and
1479                          * from merge-commit into stage 3.  We keep track
1480                          * of which side corresponds to the rename.
1481                          */
1482                         int renamed_stage = a_renames == renames1 ? 2 : 3;
1483                         int other_stage =   a_renames == renames1 ? 3 : 2;
1484
1485                         /* BUG: We should only remove ren1_src in the base
1486                          * stage and in other_stage (think of rename +
1487                          * add-source case).
1488                          */
1489                         remove_file(o, 1, ren1_src,
1490                                     renamed_stage == 2 || !was_tracked(ren1_src));
1491
1492                         oidcpy(&src_other.oid,
1493                                &ren1->src_entry->stages[other_stage].oid);
1494                         src_other.mode = ren1->src_entry->stages[other_stage].mode;
1495                         oidcpy(&dst_other.oid,
1496                                &ren1->dst_entry->stages[other_stage].oid);
1497                         dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
1498                         try_merge = 0;
1499
1500                         if (oid_eq(&src_other.oid, &null_oid)) {
1501                                 setup_rename_conflict_info(RENAME_DELETE,
1502                                                            ren1->pair,
1503                                                            NULL,
1504                                                            branch1,
1505                                                            branch2,
1506                                                            ren1->dst_entry,
1507                                                            NULL,
1508                                                            o,
1509                                                            NULL,
1510                                                            NULL);
1511                         } else if ((dst_other.mode == ren1->pair->two->mode) &&
1512                                    oid_eq(&dst_other.oid, &ren1->pair->two->oid)) {
1513                                 /*
1514                                  * Added file on the other side identical to
1515                                  * the file being renamed: clean merge.
1516                                  * Also, there is no need to overwrite the
1517                                  * file already in the working copy, so call
1518                                  * update_file_flags() instead of
1519                                  * update_file().
1520                                  */
1521                                 if (update_file_flags(o,
1522                                                       &ren1->pair->two->oid,
1523                                                       ren1->pair->two->mode,
1524                                                       ren1_dst,
1525                                                       1, /* update_cache */
1526                                                       0  /* update_wd    */))
1527                                         clean_merge = -1;
1528                         } else if (!oid_eq(&dst_other.oid, &null_oid)) {
1529                                 clean_merge = 0;
1530                                 try_merge = 1;
1531                                 output(o, 1, _("CONFLICT (rename/add): Rename %s->%s in %s. "
1532                                        "%s added in %s"),
1533                                        ren1_src, ren1_dst, branch1,
1534                                        ren1_dst, branch2);
1535                                 if (o->call_depth) {
1536                                         struct merge_file_info mfi;
1537                                         if (merge_file_one(o, ren1_dst, &null_oid, 0,
1538                                                            &ren1->pair->two->oid,
1539                                                            ren1->pair->two->mode,
1540                                                            &dst_other.oid,
1541                                                            dst_other.mode,
1542                                                            branch1, branch2, &mfi)) {
1543                                                 clean_merge = -1;
1544                                                 goto cleanup_and_return;
1545                                         }
1546                                         output(o, 1, _("Adding merged %s"), ren1_dst);
1547                                         if (update_file(o, 0, &mfi.oid,
1548                                                         mfi.mode, ren1_dst))
1549                                                 clean_merge = -1;
1550                                         try_merge = 0;
1551                                 } else {
1552                                         char *new_path = unique_path(o, ren1_dst, branch2);
1553                                         output(o, 1, _("Adding as %s instead"), new_path);
1554                                         if (update_file(o, 0, &dst_other.oid,
1555                                                         dst_other.mode, new_path))
1556                                                 clean_merge = -1;
1557                                         free(new_path);
1558                                 }
1559                         } else
1560                                 try_merge = 1;
1561
1562                         if (clean_merge < 0)
1563                                 goto cleanup_and_return;
1564                         if (try_merge) {
1565                                 struct diff_filespec *one, *a, *b;
1566                                 src_other.path = (char *)ren1_src;
1567
1568                                 one = ren1->pair->one;
1569                                 if (a_renames == renames1) {
1570                                         a = ren1->pair->two;
1571                                         b = &src_other;
1572                                 } else {
1573                                         b = ren1->pair->two;
1574                                         a = &src_other;
1575                                 }
1576                                 update_entry(ren1->dst_entry, one, a, b);
1577                                 setup_rename_conflict_info(RENAME_NORMAL,
1578                                                            ren1->pair,
1579                                                            NULL,
1580                                                            branch1,
1581                                                            NULL,
1582                                                            ren1->dst_entry,
1583                                                            NULL,
1584                                                            o,
1585                                                            NULL,
1586                                                            NULL);
1587                         }
1588                 }
1589         }
1590 cleanup_and_return:
1591         string_list_clear(&a_by_dst, 0);
1592         string_list_clear(&b_by_dst, 0);
1593
1594         return clean_merge;
1595 }
1596
1597 static struct object_id *stage_oid(const struct object_id *oid, unsigned mode)
1598 {
1599         return (is_null_oid(oid) || mode == 0) ? NULL: (struct object_id *)oid;
1600 }
1601
1602 static int read_oid_strbuf(struct merge_options *o,
1603         const struct object_id *oid, struct strbuf *dst)
1604 {
1605         void *buf;
1606         enum object_type type;
1607         unsigned long size;
1608         buf = read_sha1_file(oid->hash, &type, &size);
1609         if (!buf)
1610                 return err(o, _("cannot read object %s"), oid_to_hex(oid));
1611         if (type != OBJ_BLOB) {
1612                 free(buf);
1613                 return err(o, _("object %s is not a blob"), oid_to_hex(oid));
1614         }
1615         strbuf_attach(dst, buf, size, size + 1);
1616         return 0;
1617 }
1618
1619 static int blob_unchanged(struct merge_options *opt,
1620                           const struct object_id *o_oid,
1621                           unsigned o_mode,
1622                           const struct object_id *a_oid,
1623                           unsigned a_mode,
1624                           int renormalize, const char *path)
1625 {
1626         struct strbuf o = STRBUF_INIT;
1627         struct strbuf a = STRBUF_INIT;
1628         int ret = 0; /* assume changed for safety */
1629
1630         if (a_mode != o_mode)
1631                 return 0;
1632         if (oid_eq(o_oid, a_oid))
1633                 return 1;
1634         if (!renormalize)
1635                 return 0;
1636
1637         assert(o_oid && a_oid);
1638         if (read_oid_strbuf(opt, o_oid, &o) || read_oid_strbuf(opt, a_oid, &a))
1639                 goto error_return;
1640         /*
1641          * Note: binary | is used so that both renormalizations are
1642          * performed.  Comparison can be skipped if both files are
1643          * unchanged since their sha1s have already been compared.
1644          */
1645         if (renormalize_buffer(path, o.buf, o.len, &o) |
1646             renormalize_buffer(path, a.buf, a.len, &a))
1647                 ret = (o.len == a.len && !memcmp(o.buf, a.buf, o.len));
1648
1649 error_return:
1650         strbuf_release(&o);
1651         strbuf_release(&a);
1652         return ret;
1653 }
1654
1655 static int handle_modify_delete(struct merge_options *o,
1656                                  const char *path,
1657                                  struct object_id *o_oid, int o_mode,
1658                                  struct object_id *a_oid, int a_mode,
1659                                  struct object_id *b_oid, int b_mode)
1660 {
1661         return handle_change_delete(o,
1662                                     path,
1663                                     o_oid, o_mode,
1664                                     a_oid, a_mode,
1665                                     b_oid, b_mode,
1666                                     _("modify"), _("modified"));
1667 }
1668
1669 static int merge_content(struct merge_options *o,
1670                          const char *path,
1671                          struct object_id *o_oid, int o_mode,
1672                          struct object_id *a_oid, int a_mode,
1673                          struct object_id *b_oid, int b_mode,
1674                          struct rename_conflict_info *rename_conflict_info)
1675 {
1676         const char *reason = _("content");
1677         const char *path1 = NULL, *path2 = NULL;
1678         struct merge_file_info mfi;
1679         struct diff_filespec one, a, b;
1680         unsigned df_conflict_remains = 0;
1681
1682         if (!o_oid) {
1683                 reason = _("add/add");
1684                 o_oid = (struct object_id *)&null_oid;
1685         }
1686         one.path = a.path = b.path = (char *)path;
1687         oidcpy(&one.oid, o_oid);
1688         one.mode = o_mode;
1689         oidcpy(&a.oid, a_oid);
1690         a.mode = a_mode;
1691         oidcpy(&b.oid, b_oid);
1692         b.mode = b_mode;
1693
1694         if (rename_conflict_info) {
1695                 struct diff_filepair *pair1 = rename_conflict_info->pair1;
1696
1697                 path1 = (o->branch1 == rename_conflict_info->branch1) ?
1698                         pair1->two->path : pair1->one->path;
1699                 /* If rename_conflict_info->pair2 != NULL, we are in
1700                  * RENAME_ONE_FILE_TO_ONE case.  Otherwise, we have a
1701                  * normal rename.
1702                  */
1703                 path2 = (rename_conflict_info->pair2 ||
1704                          o->branch2 == rename_conflict_info->branch1) ?
1705                         pair1->two->path : pair1->one->path;
1706
1707                 if (dir_in_way(path, !o->call_depth))
1708                         df_conflict_remains = 1;
1709         }
1710         if (merge_file_special_markers(o, &one, &a, &b,
1711                                        o->branch1, path1,
1712                                        o->branch2, path2, &mfi))
1713                 return -1;
1714
1715         if (mfi.clean && !df_conflict_remains &&
1716             oid_eq(&mfi.oid, a_oid) && mfi.mode == a_mode) {
1717                 int path_renamed_outside_HEAD;
1718                 output(o, 3, _("Skipped %s (merged same as existing)"), path);
1719                 /*
1720                  * The content merge resulted in the same file contents we
1721                  * already had.  We can return early if those file contents
1722                  * are recorded at the correct path (which may not be true
1723                  * if the merge involves a rename).
1724                  */
1725                 path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
1726                 if (!path_renamed_outside_HEAD) {
1727                         add_cacheinfo(o, mfi.mode, &mfi.oid, path,
1728                                       0, (!o->call_depth), 0);
1729                         return mfi.clean;
1730                 }
1731         } else
1732                 output(o, 2, _("Auto-merging %s"), path);
1733
1734         if (!mfi.clean) {
1735                 if (S_ISGITLINK(mfi.mode))
1736                         reason = _("submodule");
1737                 output(o, 1, _("CONFLICT (%s): Merge conflict in %s"),
1738                                 reason, path);
1739                 if (rename_conflict_info && !df_conflict_remains)
1740                         if (update_stages(o, path, &one, &a, &b))
1741                                 return -1;
1742         }
1743
1744         if (df_conflict_remains) {
1745                 char *new_path;
1746                 if (o->call_depth) {
1747                         remove_file_from_cache(path);
1748                 } else {
1749                         if (!mfi.clean) {
1750                                 if (update_stages(o, path, &one, &a, &b))
1751                                         return -1;
1752                         } else {
1753                                 int file_from_stage2 = was_tracked(path);
1754                                 struct diff_filespec merged;
1755                                 oidcpy(&merged.oid, &mfi.oid);
1756                                 merged.mode = mfi.mode;
1757
1758                                 if (update_stages(o, path, NULL,
1759                                                   file_from_stage2 ? &merged : NULL,
1760                                                   file_from_stage2 ? NULL : &merged))
1761                                         return -1;
1762                         }
1763
1764                 }
1765                 new_path = unique_path(o, path, rename_conflict_info->branch1);
1766                 output(o, 1, _("Adding as %s instead"), new_path);
1767                 if (update_file(o, 0, &mfi.oid, mfi.mode, new_path)) {
1768                         free(new_path);
1769                         return -1;
1770                 }
1771                 free(new_path);
1772                 mfi.clean = 0;
1773         } else if (update_file(o, mfi.clean, &mfi.oid, mfi.mode, path))
1774                 return -1;
1775         return mfi.clean;
1776 }
1777
1778 /* Per entry merge function */
1779 static int process_entry(struct merge_options *o,
1780                          const char *path, struct stage_data *entry)
1781 {
1782         int clean_merge = 1;
1783         int normalize = o->renormalize;
1784         unsigned o_mode = entry->stages[1].mode;
1785         unsigned a_mode = entry->stages[2].mode;
1786         unsigned b_mode = entry->stages[3].mode;
1787         struct object_id *o_oid = stage_oid(&entry->stages[1].oid, o_mode);
1788         struct object_id *a_oid = stage_oid(&entry->stages[2].oid, a_mode);
1789         struct object_id *b_oid = stage_oid(&entry->stages[3].oid, b_mode);
1790
1791         entry->processed = 1;
1792         if (entry->rename_conflict_info) {
1793                 struct rename_conflict_info *conflict_info = entry->rename_conflict_info;
1794                 switch (conflict_info->rename_type) {
1795                 case RENAME_NORMAL:
1796                 case RENAME_ONE_FILE_TO_ONE:
1797                         clean_merge = merge_content(o, path,
1798                                                     o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
1799                                                     conflict_info);
1800                         break;
1801                 case RENAME_DELETE:
1802                         clean_merge = 0;
1803                         if (conflict_rename_delete(o,
1804                                                    conflict_info->pair1,
1805                                                    conflict_info->branch1,
1806                                                    conflict_info->branch2))
1807                                 clean_merge = -1;
1808                         break;
1809                 case RENAME_ONE_FILE_TO_TWO:
1810                         clean_merge = 0;
1811                         if (conflict_rename_rename_1to2(o, conflict_info))
1812                                 clean_merge = -1;
1813                         break;
1814                 case RENAME_TWO_FILES_TO_ONE:
1815                         clean_merge = 0;
1816                         if (conflict_rename_rename_2to1(o, conflict_info))
1817                                 clean_merge = -1;
1818                         break;
1819                 default:
1820                         entry->processed = 0;
1821                         break;
1822                 }
1823         } else if (o_oid && (!a_oid || !b_oid)) {
1824                 /* Case A: Deleted in one */
1825                 if ((!a_oid && !b_oid) ||
1826                     (!b_oid && blob_unchanged(o, o_oid, o_mode, a_oid, a_mode, normalize, path)) ||
1827                     (!a_oid && blob_unchanged(o, o_oid, o_mode, b_oid, b_mode, normalize, path))) {
1828                         /* Deleted in both or deleted in one and
1829                          * unchanged in the other */
1830                         if (a_oid)
1831                                 output(o, 2, _("Removing %s"), path);
1832                         /* do not touch working file if it did not exist */
1833                         remove_file(o, 1, path, !a_oid);
1834                 } else {
1835                         /* Modify/delete; deleted side may have put a directory in the way */
1836                         clean_merge = 0;
1837                         if (handle_modify_delete(o, path, o_oid, o_mode,
1838                                                  a_oid, a_mode, b_oid, b_mode))
1839                                 clean_merge = -1;
1840                 }
1841         } else if ((!o_oid && a_oid && !b_oid) ||
1842                    (!o_oid && !a_oid && b_oid)) {
1843                 /* Case B: Added in one. */
1844                 /* [nothing|directory] -> ([nothing|directory], file) */
1845
1846                 const char *add_branch;
1847                 const char *other_branch;
1848                 unsigned mode;
1849                 const struct object_id *oid;
1850                 const char *conf;
1851
1852                 if (a_oid) {
1853                         add_branch = o->branch1;
1854                         other_branch = o->branch2;
1855                         mode = a_mode;
1856                         oid = a_oid;
1857                         conf = _("file/directory");
1858                 } else {
1859                         add_branch = o->branch2;
1860                         other_branch = o->branch1;
1861                         mode = b_mode;
1862                         oid = b_oid;
1863                         conf = _("directory/file");
1864                 }
1865                 if (dir_in_way(path, !o->call_depth)) {
1866                         char *new_path = unique_path(o, path, add_branch);
1867                         clean_merge = 0;
1868                         output(o, 1, _("CONFLICT (%s): There is a directory with name %s in %s. "
1869                                "Adding %s as %s"),
1870                                conf, path, other_branch, path, new_path);
1871                         if (update_file(o, 0, oid, mode, new_path))
1872                                 clean_merge = -1;
1873                         else if (o->call_depth)
1874                                 remove_file_from_cache(path);
1875                         free(new_path);
1876                 } else {
1877                         output(o, 2, _("Adding %s"), path);
1878                         /* do not overwrite file if already present */
1879                         if (update_file_flags(o, oid, mode, path, 1, !a_oid))
1880                                 clean_merge = -1;
1881                 }
1882         } else if (a_oid && b_oid) {
1883                 /* Case C: Added in both (check for same permissions) and */
1884                 /* case D: Modified in both, but differently. */
1885                 clean_merge = merge_content(o, path,
1886                                             o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
1887                                             NULL);
1888         } else if (!o_oid && !a_oid && !b_oid) {
1889                 /*
1890                  * this entry was deleted altogether. a_mode == 0 means
1891                  * we had that path and want to actively remove it.
1892                  */
1893                 remove_file(o, 1, path, !a_mode);
1894         } else
1895                 die("BUG: fatal merge failure, shouldn't happen.");
1896
1897         return clean_merge;
1898 }
1899
1900 int merge_trees(struct merge_options *o,
1901                 struct tree *head,
1902                 struct tree *merge,
1903                 struct tree *common,
1904                 struct tree **result)
1905 {
1906         int code, clean;
1907
1908         if (o->subtree_shift) {
1909                 merge = shift_tree_object(head, merge, o->subtree_shift);
1910                 common = shift_tree_object(head, common, o->subtree_shift);
1911         }
1912
1913         if (oid_eq(&common->object.oid, &merge->object.oid)) {
1914                 output(o, 0, _("Already up-to-date!"));
1915                 *result = head;
1916                 return 1;
1917         }
1918
1919         code = git_merge_trees(o->call_depth, common, head, merge);
1920
1921         if (code != 0) {
1922                 if (show(o, 4) || o->call_depth)
1923                         err(o, _("merging of trees %s and %s failed"),
1924                             oid_to_hex(&head->object.oid),
1925                             oid_to_hex(&merge->object.oid));
1926                 return -1;
1927         }
1928
1929         if (unmerged_cache()) {
1930                 struct string_list *entries, *re_head, *re_merge;
1931                 int i;
1932                 string_list_clear(&o->current_file_set, 1);
1933                 string_list_clear(&o->current_directory_set, 1);
1934                 get_files_dirs(o, head);
1935                 get_files_dirs(o, merge);
1936
1937                 entries = get_unmerged();
1938                 record_df_conflict_files(o, entries);
1939                 re_head  = get_renames(o, head, common, head, merge, entries);
1940                 re_merge = get_renames(o, merge, common, head, merge, entries);
1941                 clean = process_renames(o, re_head, re_merge);
1942                 if (clean < 0)
1943                         return clean;
1944                 for (i = entries->nr-1; 0 <= i; i--) {
1945                         const char *path = entries->items[i].string;
1946                         struct stage_data *e = entries->items[i].util;
1947                         if (!e->processed) {
1948                                 int ret = process_entry(o, path, e);
1949                                 if (!ret)
1950                                         clean = 0;
1951                                 else if (ret < 0)
1952                                         return ret;
1953                         }
1954                 }
1955                 for (i = 0; i < entries->nr; i++) {
1956                         struct stage_data *e = entries->items[i].util;
1957                         if (!e->processed)
1958                                 die("BUG: unprocessed path??? %s",
1959                                     entries->items[i].string);
1960                 }
1961
1962                 string_list_clear(re_merge, 0);
1963                 string_list_clear(re_head, 0);
1964                 string_list_clear(entries, 1);
1965
1966                 free(re_merge);
1967                 free(re_head);
1968                 free(entries);
1969         }
1970         else
1971                 clean = 1;
1972
1973         if (o->call_depth && !(*result = write_tree_from_memory(o)))
1974                 return -1;
1975
1976         return clean;
1977 }
1978
1979 static struct commit_list *reverse_commit_list(struct commit_list *list)
1980 {
1981         struct commit_list *next = NULL, *current, *backup;
1982         for (current = list; current; current = backup) {
1983                 backup = current->next;
1984                 current->next = next;
1985                 next = current;
1986         }
1987         return next;
1988 }
1989
1990 /*
1991  * Merge the commits h1 and h2, return the resulting virtual
1992  * commit object and a flag indicating the cleanness of the merge.
1993  */
1994 int merge_recursive(struct merge_options *o,
1995                     struct commit *h1,
1996                     struct commit *h2,
1997                     struct commit_list *ca,
1998                     struct commit **result)
1999 {
2000         struct commit_list *iter;
2001         struct commit *merged_common_ancestors;
2002         struct tree *mrtree = mrtree;
2003         int clean;
2004
2005         if (show(o, 4)) {
2006                 output(o, 4, _("Merging:"));
2007                 output_commit_title(o, h1);
2008                 output_commit_title(o, h2);
2009         }
2010
2011         if (!ca) {
2012                 ca = get_merge_bases(h1, h2);
2013                 ca = reverse_commit_list(ca);
2014         }
2015
2016         if (show(o, 5)) {
2017                 unsigned cnt = commit_list_count(ca);
2018
2019                 output(o, 5, Q_("found %u common ancestor:",
2020                                 "found %u common ancestors:", cnt), cnt);
2021                 for (iter = ca; iter; iter = iter->next)
2022                         output_commit_title(o, iter->item);
2023         }
2024
2025         merged_common_ancestors = pop_commit(&ca);
2026         if (merged_common_ancestors == NULL) {
2027                 /* if there is no common ancestor, use an empty tree */
2028                 struct tree *tree;
2029
2030                 tree = lookup_tree(EMPTY_TREE_SHA1_BIN);
2031                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
2032         }
2033
2034         for (iter = ca; iter; iter = iter->next) {
2035                 const char *saved_b1, *saved_b2;
2036                 o->call_depth++;
2037                 /*
2038                  * When the merge fails, the result contains files
2039                  * with conflict markers. The cleanness flag is
2040                  * ignored (unless indicating an error), it was never
2041                  * actually used, as result of merge_trees has always
2042                  * overwritten it: the committed "conflicts" were
2043                  * already resolved.
2044                  */
2045                 discard_cache();
2046                 saved_b1 = o->branch1;
2047                 saved_b2 = o->branch2;
2048                 o->branch1 = "Temporary merge branch 1";
2049                 o->branch2 = "Temporary merge branch 2";
2050                 if (merge_recursive(o, merged_common_ancestors, iter->item,
2051                                     NULL, &merged_common_ancestors) < 0)
2052                         return -1;
2053                 o->branch1 = saved_b1;
2054                 o->branch2 = saved_b2;
2055                 o->call_depth--;
2056
2057                 if (!merged_common_ancestors)
2058                         return err(o, _("merge returned no commit"));
2059         }
2060
2061         discard_cache();
2062         if (!o->call_depth)
2063                 read_cache();
2064
2065         o->ancestor = "merged common ancestors";
2066         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
2067                             &mrtree);
2068         if (clean < 0) {
2069                 flush_output(o);
2070                 return clean;
2071         }
2072
2073         if (o->call_depth) {
2074                 *result = make_virtual_commit(mrtree, "merged tree");
2075                 commit_list_insert(h1, &(*result)->parents);
2076                 commit_list_insert(h2, &(*result)->parents->next);
2077         }
2078         flush_output(o);
2079         if (!o->call_depth && o->buffer_output < 2)
2080                 strbuf_release(&o->obuf);
2081         if (show(o, 2))
2082                 diff_warn_rename_limit("merge.renamelimit",
2083                                        o->needed_rename_limit, 0);
2084         return clean;
2085 }
2086
2087 static struct commit *get_ref(const struct object_id *oid, const char *name)
2088 {
2089         struct object *object;
2090
2091         object = deref_tag(parse_object(oid->hash), name, strlen(name));
2092         if (!object)
2093                 return NULL;
2094         if (object->type == OBJ_TREE)
2095                 return make_virtual_commit((struct tree*)object, name);
2096         if (object->type != OBJ_COMMIT)
2097                 return NULL;
2098         if (parse_commit((struct commit *)object))
2099                 return NULL;
2100         return (struct commit *)object;
2101 }
2102
2103 int merge_recursive_generic(struct merge_options *o,
2104                             const struct object_id *head,
2105                             const struct object_id *merge,
2106                             int num_base_list,
2107                             const struct object_id **base_list,
2108                             struct commit **result)
2109 {
2110         int clean;
2111         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
2112         struct commit *head_commit = get_ref(head, o->branch1);
2113         struct commit *next_commit = get_ref(merge, o->branch2);
2114         struct commit_list *ca = NULL;
2115
2116         if (base_list) {
2117                 int i;
2118                 for (i = 0; i < num_base_list; ++i) {
2119                         struct commit *base;
2120                         if (!(base = get_ref(base_list[i], oid_to_hex(base_list[i]))))
2121                                 return err(o, _("Could not parse object '%s'"),
2122                                         oid_to_hex(base_list[i]));
2123                         commit_list_insert(base, &ca);
2124                 }
2125         }
2126
2127         hold_locked_index(lock, 1);
2128         clean = merge_recursive(o, head_commit, next_commit, ca,
2129                         result);
2130         if (clean < 0)
2131                 return clean;
2132
2133         if (active_cache_changed &&
2134             write_locked_index(&the_index, lock, COMMIT_LOCK))
2135                 return err(o, _("Unable to write index."));
2136
2137         return clean ? 0 : 1;
2138 }
2139
2140 static void merge_recursive_config(struct merge_options *o)
2141 {
2142         git_config_get_int("merge.verbosity", &o->verbosity);
2143         git_config_get_int("diff.renamelimit", &o->diff_rename_limit);
2144         git_config_get_int("merge.renamelimit", &o->merge_rename_limit);
2145         git_config(git_xmerge_config, NULL);
2146 }
2147
2148 void init_merge_options(struct merge_options *o)
2149 {
2150         memset(o, 0, sizeof(struct merge_options));
2151         o->verbosity = 2;
2152         o->buffer_output = 1;
2153         o->diff_rename_limit = -1;
2154         o->merge_rename_limit = -1;
2155         o->renormalize = 0;
2156         o->detect_rename = 1;
2157         merge_recursive_config(o);
2158         if (getenv("GIT_MERGE_VERBOSITY"))
2159                 o->verbosity =
2160                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
2161         if (o->verbosity >= 5)
2162                 o->buffer_output = 0;
2163         strbuf_init(&o->obuf, 0);
2164         string_list_init(&o->current_file_set, 1);
2165         string_list_init(&o->current_directory_set, 1);
2166         string_list_init(&o->df_conflict_file_set, 1);
2167 }
2168
2169 int parse_merge_opt(struct merge_options *o, const char *s)
2170 {
2171         const char *arg;
2172
2173         if (!s || !*s)
2174                 return -1;
2175         if (!strcmp(s, "ours"))
2176                 o->recursive_variant = MERGE_RECURSIVE_OURS;
2177         else if (!strcmp(s, "theirs"))
2178                 o->recursive_variant = MERGE_RECURSIVE_THEIRS;
2179         else if (!strcmp(s, "subtree"))
2180                 o->subtree_shift = "";
2181         else if (skip_prefix(s, "subtree=", &arg))
2182                 o->subtree_shift = arg;
2183         else if (!strcmp(s, "patience"))
2184                 o->xdl_opts = DIFF_WITH_ALG(o, PATIENCE_DIFF);
2185         else if (!strcmp(s, "histogram"))
2186                 o->xdl_opts = DIFF_WITH_ALG(o, HISTOGRAM_DIFF);
2187         else if (skip_prefix(s, "diff-algorithm=", &arg)) {
2188                 long value = parse_algorithm_value(arg);
2189                 if (value < 0)
2190                         return -1;
2191                 /* clear out previous settings */
2192                 DIFF_XDL_CLR(o, NEED_MINIMAL);
2193                 o->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
2194                 o->xdl_opts |= value;
2195         }
2196         else if (!strcmp(s, "ignore-space-change"))
2197                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_CHANGE;
2198         else if (!strcmp(s, "ignore-all-space"))
2199                 o->xdl_opts |= XDF_IGNORE_WHITESPACE;
2200         else if (!strcmp(s, "ignore-space-at-eol"))
2201                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_AT_EOL;
2202         else if (!strcmp(s, "renormalize"))
2203                 o->renormalize = 1;
2204         else if (!strcmp(s, "no-renormalize"))
2205                 o->renormalize = 0;
2206         else if (!strcmp(s, "no-renames"))
2207                 o->detect_rename = 0;
2208         else if (!strcmp(s, "find-renames")) {
2209                 o->detect_rename = 1;
2210                 o->rename_score = 0;
2211         }
2212         else if (skip_prefix(s, "find-renames=", &arg) ||
2213                  skip_prefix(s, "rename-threshold=", &arg)) {
2214                 if ((o->rename_score = parse_rename_score(&arg)) == -1 || *arg != 0)
2215                         return -1;
2216                 o->detect_rename = 1;
2217         }
2218         else
2219                 return -1;
2220         return 0;
2221 }