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[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 "advice.h"
7 #include "cache.h"
8 #include "cache-tree.h"
9 #include "commit.h"
10 #include "blob.h"
11 #include "builtin.h"
12 #include "tree-walk.h"
13 #include "diff.h"
14 #include "diffcore.h"
15 #include "tag.h"
16 #include "unpack-trees.h"
17 #include "string-list.h"
18 #include "xdiff-interface.h"
19 #include "ll-merge.h"
20 #include "attr.h"
21 #include "merge-recursive.h"
22 #include "dir.h"
23
24 static struct tree *shift_tree_object(struct tree *one, struct tree *two)
25 {
26         unsigned char shifted[20];
27
28         /*
29          * NEEDSWORK: this limits the recursion depth to hardcoded
30          * value '2' to avoid excessive overhead.
31          */
32         shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
33         if (!hashcmp(two->object.sha1, shifted))
34                 return two;
35         return lookup_tree(shifted);
36 }
37
38 /*
39  * A virtual commit has (const char *)commit->util set to the name.
40  */
41
42 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
43 {
44         struct commit *commit = xcalloc(1, sizeof(struct commit));
45         commit->tree = tree;
46         commit->util = (void*)comment;
47         /* avoid warnings */
48         commit->object.parsed = 1;
49         return commit;
50 }
51
52 /*
53  * Since we use get_tree_entry(), which does not put the read object into
54  * the object pool, we cannot rely on a == b.
55  */
56 static int sha_eq(const unsigned char *a, const unsigned char *b)
57 {
58         if (!a && !b)
59                 return 2;
60         return a && b && hashcmp(a, b) == 0;
61 }
62
63 /*
64  * Since we want to write the index eventually, we cannot reuse the index
65  * for these (temporary) data.
66  */
67 struct stage_data
68 {
69         struct
70         {
71                 unsigned mode;
72                 unsigned char sha[20];
73         } stages[4];
74         unsigned processed:1;
75 };
76
77 static int show(struct merge_options *o, int v)
78 {
79         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
80 }
81
82 static void flush_output(struct merge_options *o)
83 {
84         if (o->obuf.len) {
85                 fputs(o->obuf.buf, stdout);
86                 strbuf_reset(&o->obuf);
87         }
88 }
89
90 __attribute__((format (printf, 3, 4)))
91 static void output(struct merge_options *o, int v, const char *fmt, ...)
92 {
93         int len;
94         va_list ap;
95
96         if (!show(o, v))
97                 return;
98
99         strbuf_grow(&o->obuf, o->call_depth * 2 + 2);
100         memset(o->obuf.buf + o->obuf.len, ' ', o->call_depth * 2);
101         strbuf_setlen(&o->obuf, o->obuf.len + o->call_depth * 2);
102
103         va_start(ap, fmt);
104         len = vsnprintf(o->obuf.buf + o->obuf.len, strbuf_avail(&o->obuf), fmt, ap);
105         va_end(ap);
106
107         if (len < 0)
108                 len = 0;
109         if (len >= strbuf_avail(&o->obuf)) {
110                 strbuf_grow(&o->obuf, len + 2);
111                 va_start(ap, fmt);
112                 len = vsnprintf(o->obuf.buf + o->obuf.len, strbuf_avail(&o->obuf), fmt, ap);
113                 va_end(ap);
114                 if (len >= strbuf_avail(&o->obuf)) {
115                         die("this should not happen, your snprintf is broken");
116                 }
117         }
118         strbuf_setlen(&o->obuf, o->obuf.len + len);
119         strbuf_add(&o->obuf, "\n", 1);
120         if (!o->buffer_output)
121                 flush_output(o);
122 }
123
124 static void output_commit_title(struct merge_options *o, struct commit *commit)
125 {
126         int i;
127         flush_output(o);
128         for (i = o->call_depth; i--;)
129                 fputs("  ", stdout);
130         if (commit->util)
131                 printf("virtual %s\n", (char *)commit->util);
132         else {
133                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
134                 if (parse_commit(commit) != 0)
135                         printf("(bad commit)\n");
136                 else {
137                         const char *s;
138                         int len;
139                         for (s = commit->buffer; *s; s++)
140                                 if (*s == '\n' && s[1] == '\n') {
141                                         s += 2;
142                                         break;
143                                 }
144                         for (len = 0; s[len] && '\n' != s[len]; len++)
145                                 ; /* do nothing */
146                         printf("%.*s\n", len, s);
147                 }
148         }
149 }
150
151 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
152                 const char *path, int stage, int refresh, int options)
153 {
154         struct cache_entry *ce;
155         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
156         if (!ce)
157                 return error("addinfo_cache failed for path '%s'", path);
158         return add_cache_entry(ce, options);
159 }
160
161 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
162 {
163         parse_tree(tree);
164         init_tree_desc(desc, tree->buffer, tree->size);
165 }
166
167 static int git_merge_trees(int index_only,
168                            struct tree *common,
169                            struct tree *head,
170                            struct tree *merge)
171 {
172         int rc;
173         struct tree_desc t[3];
174         struct unpack_trees_options opts;
175
176         memset(&opts, 0, sizeof(opts));
177         if (index_only)
178                 opts.index_only = 1;
179         else
180                 opts.update = 1;
181         opts.merge = 1;
182         opts.head_idx = 2;
183         opts.fn = threeway_merge;
184         opts.src_index = &the_index;
185         opts.dst_index = &the_index;
186         opts.msgs = get_porcelain_error_msgs();
187
188         init_tree_desc_from_tree(t+0, common);
189         init_tree_desc_from_tree(t+1, head);
190         init_tree_desc_from_tree(t+2, merge);
191
192         rc = unpack_trees(3, t, &opts);
193         cache_tree_free(&active_cache_tree);
194         return rc;
195 }
196
197 struct tree *write_tree_from_memory(struct merge_options *o)
198 {
199         struct tree *result = NULL;
200
201         if (unmerged_cache()) {
202                 int i;
203                 output(o, 0, "There are unmerged index entries:");
204                 for (i = 0; i < active_nr; i++) {
205                         struct cache_entry *ce = active_cache[i];
206                         if (ce_stage(ce))
207                                 output(o, 0, "%d %.*s", ce_stage(ce),
208                                        (int)ce_namelen(ce), ce->name);
209                 }
210                 return NULL;
211         }
212
213         if (!active_cache_tree)
214                 active_cache_tree = cache_tree();
215
216         if (!cache_tree_fully_valid(active_cache_tree) &&
217             cache_tree_update(active_cache_tree,
218                               active_cache, active_nr, 0, 0) < 0)
219                 die("error building trees");
220
221         result = lookup_tree(active_cache_tree->sha1);
222
223         return result;
224 }
225
226 static int save_files_dirs(const unsigned char *sha1,
227                 const char *base, int baselen, const char *path,
228                 unsigned int mode, int stage, void *context)
229 {
230         int len = strlen(path);
231         char *newpath = xmalloc(baselen + len + 1);
232         struct merge_options *o = context;
233
234         memcpy(newpath, base, baselen);
235         memcpy(newpath + baselen, path, len);
236         newpath[baselen + len] = '\0';
237
238         if (S_ISDIR(mode))
239                 string_list_insert(newpath, &o->current_directory_set);
240         else
241                 string_list_insert(newpath, &o->current_file_set);
242         free(newpath);
243
244         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
245 }
246
247 static int get_files_dirs(struct merge_options *o, struct tree *tree)
248 {
249         int n;
250         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs, o))
251                 return 0;
252         n = o->current_file_set.nr + o->current_directory_set.nr;
253         return n;
254 }
255
256 /*
257  * Returns an index_entry instance which doesn't have to correspond to
258  * a real cache entry in Git's index.
259  */
260 static struct stage_data *insert_stage_data(const char *path,
261                 struct tree *o, struct tree *a, struct tree *b,
262                 struct string_list *entries)
263 {
264         struct string_list_item *item;
265         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
266         get_tree_entry(o->object.sha1, path,
267                         e->stages[1].sha, &e->stages[1].mode);
268         get_tree_entry(a->object.sha1, path,
269                         e->stages[2].sha, &e->stages[2].mode);
270         get_tree_entry(b->object.sha1, path,
271                         e->stages[3].sha, &e->stages[3].mode);
272         item = string_list_insert(path, entries);
273         item->util = e;
274         return e;
275 }
276
277 /*
278  * Create a dictionary mapping file names to stage_data objects. The
279  * dictionary contains one entry for every path with a non-zero stage entry.
280  */
281 static struct string_list *get_unmerged(void)
282 {
283         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
284         int i;
285
286         unmerged->strdup_strings = 1;
287
288         for (i = 0; i < active_nr; i++) {
289                 struct string_list_item *item;
290                 struct stage_data *e;
291                 struct cache_entry *ce = active_cache[i];
292                 if (!ce_stage(ce))
293                         continue;
294
295                 item = string_list_lookup(ce->name, unmerged);
296                 if (!item) {
297                         item = string_list_insert(ce->name, unmerged);
298                         item->util = xcalloc(1, sizeof(struct stage_data));
299                 }
300                 e = item->util;
301                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
302                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
303         }
304
305         return unmerged;
306 }
307
308 struct rename
309 {
310         struct diff_filepair *pair;
311         struct stage_data *src_entry;
312         struct stage_data *dst_entry;
313         unsigned processed:1;
314 };
315
316 /*
317  * Get information of all renames which occurred between 'o_tree' and
318  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
319  * 'b_tree') to be able to associate the correct cache entries with
320  * the rename information. 'tree' is always equal to either a_tree or b_tree.
321  */
322 static struct string_list *get_renames(struct merge_options *o,
323                                        struct tree *tree,
324                                        struct tree *o_tree,
325                                        struct tree *a_tree,
326                                        struct tree *b_tree,
327                                        struct string_list *entries)
328 {
329         int i;
330         struct string_list *renames;
331         struct diff_options opts;
332
333         renames = xcalloc(1, sizeof(struct string_list));
334         diff_setup(&opts);
335         DIFF_OPT_SET(&opts, RECURSIVE);
336         opts.detect_rename = DIFF_DETECT_RENAME;
337         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
338                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
339                             500;
340         opts.warn_on_too_large_rename = 1;
341         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
342         if (diff_setup_done(&opts) < 0)
343                 die("diff setup failed");
344         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
345         diffcore_std(&opts);
346         for (i = 0; i < diff_queued_diff.nr; ++i) {
347                 struct string_list_item *item;
348                 struct rename *re;
349                 struct diff_filepair *pair = diff_queued_diff.queue[i];
350                 if (pair->status != 'R') {
351                         diff_free_filepair(pair);
352                         continue;
353                 }
354                 re = xmalloc(sizeof(*re));
355                 re->processed = 0;
356                 re->pair = pair;
357                 item = string_list_lookup(re->pair->one->path, entries);
358                 if (!item)
359                         re->src_entry = insert_stage_data(re->pair->one->path,
360                                         o_tree, a_tree, b_tree, entries);
361                 else
362                         re->src_entry = item->util;
363
364                 item = string_list_lookup(re->pair->two->path, entries);
365                 if (!item)
366                         re->dst_entry = insert_stage_data(re->pair->two->path,
367                                         o_tree, a_tree, b_tree, entries);
368                 else
369                         re->dst_entry = item->util;
370                 item = string_list_insert(pair->one->path, renames);
371                 item->util = re;
372         }
373         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
374         diff_queued_diff.nr = 0;
375         diff_flush(&opts);
376         return renames;
377 }
378
379 static int update_stages(const char *path, struct diff_filespec *o,
380                          struct diff_filespec *a, struct diff_filespec *b,
381                          int clear)
382 {
383         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
384         if (clear)
385                 if (remove_file_from_cache(path))
386                         return -1;
387         if (o)
388                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
389                         return -1;
390         if (a)
391                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
392                         return -1;
393         if (b)
394                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
395                         return -1;
396         return 0;
397 }
398
399 static int remove_file(struct merge_options *o, int clean,
400                        const char *path, int no_wd)
401 {
402         int update_cache = o->call_depth || clean;
403         int update_working_directory = !o->call_depth && !no_wd;
404
405         if (update_cache) {
406                 if (remove_file_from_cache(path))
407                         return -1;
408         }
409         if (update_working_directory) {
410                 if (remove_path(path) && errno != ENOENT)
411                         return -1;
412         }
413         return 0;
414 }
415
416 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
417 {
418         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
419         int suffix = 0;
420         struct stat st;
421         char *p = newpath + strlen(path);
422         strcpy(newpath, path);
423         *(p++) = '~';
424         strcpy(p, branch);
425         for (; *p; ++p)
426                 if ('/' == *p)
427                         *p = '_';
428         while (string_list_has_string(&o->current_file_set, newpath) ||
429                string_list_has_string(&o->current_directory_set, newpath) ||
430                lstat(newpath, &st) == 0)
431                 sprintf(p, "_%d", suffix++);
432
433         string_list_insert(newpath, &o->current_file_set);
434         return newpath;
435 }
436
437 static void flush_buffer(int fd, const char *buf, unsigned long size)
438 {
439         while (size > 0) {
440                 long ret = write_in_full(fd, buf, size);
441                 if (ret < 0) {
442                         /* Ignore epipe */
443                         if (errno == EPIPE)
444                                 break;
445                         die_errno("merge-recursive");
446                 } else if (!ret) {
447                         die("merge-recursive: disk full?");
448                 }
449                 size -= ret;
450                 buf += ret;
451         }
452 }
453
454 static int would_lose_untracked(const char *path)
455 {
456         int pos = cache_name_pos(path, strlen(path));
457
458         if (pos < 0)
459                 pos = -1 - pos;
460         while (pos < active_nr &&
461                !strcmp(path, active_cache[pos]->name)) {
462                 /*
463                  * If stage #0, it is definitely tracked.
464                  * If it has stage #2 then it was tracked
465                  * before this merge started.  All other
466                  * cases the path was not tracked.
467                  */
468                 switch (ce_stage(active_cache[pos])) {
469                 case 0:
470                 case 2:
471                         return 0;
472                 }
473                 pos++;
474         }
475         return file_exists(path);
476 }
477
478 static int make_room_for_path(const char *path)
479 {
480         int status;
481         const char *msg = "failed to create path '%s'%s";
482
483         status = safe_create_leading_directories_const(path);
484         if (status) {
485                 if (status == -3) {
486                         /* something else exists */
487                         error(msg, path, ": perhaps a D/F conflict?");
488                         return -1;
489                 }
490                 die(msg, path, "");
491         }
492
493         /*
494          * Do not unlink a file in the work tree if we are not
495          * tracking it.
496          */
497         if (would_lose_untracked(path))
498                 return error("refusing to lose untracked file at '%s'",
499                              path);
500
501         /* Successful unlink is good.. */
502         if (!unlink(path))
503                 return 0;
504         /* .. and so is no existing file */
505         if (errno == ENOENT)
506                 return 0;
507         /* .. but not some other error (who really cares what?) */
508         return error(msg, path, ": perhaps a D/F conflict?");
509 }
510
511 static void update_file_flags(struct merge_options *o,
512                               const unsigned char *sha,
513                               unsigned mode,
514                               const char *path,
515                               int update_cache,
516                               int update_wd)
517 {
518         if (o->call_depth)
519                 update_wd = 0;
520
521         if (update_wd) {
522                 enum object_type type;
523                 void *buf;
524                 unsigned long size;
525
526                 if (S_ISGITLINK(mode))
527                         /*
528                          * We may later decide to recursively descend into
529                          * the submodule directory and update its index
530                          * and/or work tree, but we do not do that now.
531                          */
532                         goto update_index;
533
534                 buf = read_sha1_file(sha, &type, &size);
535                 if (!buf)
536                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
537                 if (type != OBJ_BLOB)
538                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
539                 if (S_ISREG(mode)) {
540                         struct strbuf strbuf = STRBUF_INIT;
541                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
542                                 free(buf);
543                                 size = strbuf.len;
544                                 buf = strbuf_detach(&strbuf, NULL);
545                         }
546                 }
547
548                 if (make_room_for_path(path) < 0) {
549                         update_wd = 0;
550                         free(buf);
551                         goto update_index;
552                 }
553                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
554                         int fd;
555                         if (mode & 0100)
556                                 mode = 0777;
557                         else
558                                 mode = 0666;
559                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
560                         if (fd < 0)
561                                 die_errno("failed to open '%s'", path);
562                         flush_buffer(fd, buf, size);
563                         close(fd);
564                 } else if (S_ISLNK(mode)) {
565                         char *lnk = xmemdupz(buf, size);
566                         safe_create_leading_directories_const(path);
567                         unlink(path);
568                         if (symlink(lnk, path))
569                                 die_errno("failed to symlink '%s'", path);
570                         free(lnk);
571                 } else
572                         die("do not know what to do with %06o %s '%s'",
573                             mode, sha1_to_hex(sha), path);
574                 free(buf);
575         }
576  update_index:
577         if (update_cache)
578                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
579 }
580
581 static void update_file(struct merge_options *o,
582                         int clean,
583                         const unsigned char *sha,
584                         unsigned mode,
585                         const char *path)
586 {
587         update_file_flags(o, sha, mode, path, o->call_depth || clean, !o->call_depth);
588 }
589
590 /* Low level file merging, update and removal */
591
592 struct merge_file_info
593 {
594         unsigned char sha[20];
595         unsigned mode;
596         unsigned clean:1,
597                  merge:1;
598 };
599
600 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
601 {
602         unsigned long size;
603         enum object_type type;
604
605         if (!hashcmp(sha1, null_sha1)) {
606                 mm->ptr = xstrdup("");
607                 mm->size = 0;
608                 return;
609         }
610
611         mm->ptr = read_sha1_file(sha1, &type, &size);
612         if (!mm->ptr || type != OBJ_BLOB)
613                 die("unable to read blob object %s", sha1_to_hex(sha1));
614         mm->size = size;
615 }
616
617 static int merge_3way(struct merge_options *o,
618                       mmbuffer_t *result_buf,
619                       struct diff_filespec *one,
620                       struct diff_filespec *a,
621                       struct diff_filespec *b,
622                       const char *branch1,
623                       const char *branch2)
624 {
625         mmfile_t orig, src1, src2;
626         char *name1, *name2;
627         int merge_status;
628
629         if (strcmp(a->path, b->path)) {
630                 name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
631                 name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
632         } else {
633                 name1 = xstrdup(mkpath("%s", branch1));
634                 name2 = xstrdup(mkpath("%s", branch2));
635         }
636
637         fill_mm(one->sha1, &orig);
638         fill_mm(a->sha1, &src1);
639         fill_mm(b->sha1, &src2);
640
641         merge_status = ll_merge(result_buf, a->path, &orig,
642                                 &src1, name1, &src2, name2,
643                                 o->call_depth);
644
645         free(name1);
646         free(name2);
647         free(orig.ptr);
648         free(src1.ptr);
649         free(src2.ptr);
650         return merge_status;
651 }
652
653 static struct merge_file_info merge_file(struct merge_options *o,
654                                          struct diff_filespec *one,
655                                          struct diff_filespec *a,
656                                          struct diff_filespec *b,
657                                          const char *branch1,
658                                          const char *branch2)
659 {
660         struct merge_file_info result;
661         result.merge = 0;
662         result.clean = 1;
663
664         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
665                 result.clean = 0;
666                 if (S_ISREG(a->mode)) {
667                         result.mode = a->mode;
668                         hashcpy(result.sha, a->sha1);
669                 } else {
670                         result.mode = b->mode;
671                         hashcpy(result.sha, b->sha1);
672                 }
673         } else {
674                 if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
675                         result.merge = 1;
676
677                 /*
678                  * Merge modes
679                  */
680                 if (a->mode == b->mode || a->mode == one->mode)
681                         result.mode = b->mode;
682                 else {
683                         result.mode = a->mode;
684                         if (b->mode != one->mode) {
685                                 result.clean = 0;
686                                 result.merge = 1;
687                         }
688                 }
689
690                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
691                         hashcpy(result.sha, b->sha1);
692                 else if (sha_eq(b->sha1, one->sha1))
693                         hashcpy(result.sha, a->sha1);
694                 else if (S_ISREG(a->mode)) {
695                         mmbuffer_t result_buf;
696                         int merge_status;
697
698                         merge_status = merge_3way(o, &result_buf, one, a, b,
699                                                   branch1, branch2);
700
701                         if ((merge_status < 0) || !result_buf.ptr)
702                                 die("Failed to execute internal merge");
703
704                         if (write_sha1_file(result_buf.ptr, result_buf.size,
705                                             blob_type, result.sha))
706                                 die("Unable to add %s to database",
707                                     a->path);
708
709                         free(result_buf.ptr);
710                         result.clean = (merge_status == 0);
711                 } else if (S_ISGITLINK(a->mode)) {
712                         result.clean = 0;
713                         hashcpy(result.sha, a->sha1);
714                 } else if (S_ISLNK(a->mode)) {
715                         hashcpy(result.sha, a->sha1);
716
717                         if (!sha_eq(a->sha1, b->sha1))
718                                 result.clean = 0;
719                 } else {
720                         die("unsupported object type in the tree");
721                 }
722         }
723
724         return result;
725 }
726
727 static void conflict_rename_rename(struct merge_options *o,
728                                    struct rename *ren1,
729                                    const char *branch1,
730                                    struct rename *ren2,
731                                    const char *branch2)
732 {
733         char *del[2];
734         int delp = 0;
735         const char *ren1_dst = ren1->pair->two->path;
736         const char *ren2_dst = ren2->pair->two->path;
737         const char *dst_name1 = ren1_dst;
738         const char *dst_name2 = ren2_dst;
739         if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
740                 dst_name1 = del[delp++] = unique_path(o, ren1_dst, branch1);
741                 output(o, 1, "%s is a directory in %s adding as %s instead",
742                        ren1_dst, branch2, dst_name1);
743                 remove_file(o, 0, ren1_dst, 0);
744         }
745         if (string_list_has_string(&o->current_directory_set, ren2_dst)) {
746                 dst_name2 = del[delp++] = unique_path(o, ren2_dst, branch2);
747                 output(o, 1, "%s is a directory in %s adding as %s instead",
748                        ren2_dst, branch1, dst_name2);
749                 remove_file(o, 0, ren2_dst, 0);
750         }
751         if (o->call_depth) {
752                 remove_file_from_cache(dst_name1);
753                 remove_file_from_cache(dst_name2);
754                 /*
755                  * Uncomment to leave the conflicting names in the resulting tree
756                  *
757                  * update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
758                  * update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
759                  */
760         } else {
761                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
762                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
763         }
764         while (delp--)
765                 free(del[delp]);
766 }
767
768 static void conflict_rename_dir(struct merge_options *o,
769                                 struct rename *ren1,
770                                 const char *branch1)
771 {
772         char *new_path = unique_path(o, ren1->pair->two->path, branch1);
773         output(o, 1, "Renaming %s to %s instead", ren1->pair->one->path, new_path);
774         remove_file(o, 0, ren1->pair->two->path, 0);
775         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
776         free(new_path);
777 }
778
779 static void conflict_rename_rename_2(struct merge_options *o,
780                                      struct rename *ren1,
781                                      const char *branch1,
782                                      struct rename *ren2,
783                                      const char *branch2)
784 {
785         char *new_path1 = unique_path(o, ren1->pair->two->path, branch1);
786         char *new_path2 = unique_path(o, ren2->pair->two->path, branch2);
787         output(o, 1, "Renaming %s to %s and %s to %s instead",
788                ren1->pair->one->path, new_path1,
789                ren2->pair->one->path, new_path2);
790         remove_file(o, 0, ren1->pair->two->path, 0);
791         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
792         update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
793         free(new_path2);
794         free(new_path1);
795 }
796
797 static int process_renames(struct merge_options *o,
798                            struct string_list *a_renames,
799                            struct string_list *b_renames)
800 {
801         int clean_merge = 1, i, j;
802         struct string_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
803         const struct rename *sre;
804
805         for (i = 0; i < a_renames->nr; i++) {
806                 sre = a_renames->items[i].util;
807                 string_list_insert(sre->pair->two->path, &a_by_dst)->util
808                         = sre->dst_entry;
809         }
810         for (i = 0; i < b_renames->nr; i++) {
811                 sre = b_renames->items[i].util;
812                 string_list_insert(sre->pair->two->path, &b_by_dst)->util
813                         = sre->dst_entry;
814         }
815
816         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
817                 char *src;
818                 struct string_list *renames1, *renames2Dst;
819                 struct rename *ren1 = NULL, *ren2 = NULL;
820                 const char *branch1, *branch2;
821                 const char *ren1_src, *ren1_dst;
822
823                 if (i >= a_renames->nr) {
824                         ren2 = b_renames->items[j++].util;
825                 } else if (j >= b_renames->nr) {
826                         ren1 = a_renames->items[i++].util;
827                 } else {
828                         int compare = strcmp(a_renames->items[i].string,
829                                              b_renames->items[j].string);
830                         if (compare <= 0)
831                                 ren1 = a_renames->items[i++].util;
832                         if (compare >= 0)
833                                 ren2 = b_renames->items[j++].util;
834                 }
835
836                 /* TODO: refactor, so that 1/2 are not needed */
837                 if (ren1) {
838                         renames1 = a_renames;
839                         renames2Dst = &b_by_dst;
840                         branch1 = o->branch1;
841                         branch2 = o->branch2;
842                 } else {
843                         struct rename *tmp;
844                         renames1 = b_renames;
845                         renames2Dst = &a_by_dst;
846                         branch1 = o->branch2;
847                         branch2 = o->branch1;
848                         tmp = ren2;
849                         ren2 = ren1;
850                         ren1 = tmp;
851                 }
852                 src = ren1->pair->one->path;
853
854                 ren1->dst_entry->processed = 1;
855                 ren1->src_entry->processed = 1;
856
857                 if (ren1->processed)
858                         continue;
859                 ren1->processed = 1;
860
861                 ren1_src = ren1->pair->one->path;
862                 ren1_dst = ren1->pair->two->path;
863
864                 if (ren2) {
865                         const char *ren2_src = ren2->pair->one->path;
866                         const char *ren2_dst = ren2->pair->two->path;
867                         /* Renamed in 1 and renamed in 2 */
868                         if (strcmp(ren1_src, ren2_src) != 0)
869                                 die("ren1.src != ren2.src");
870                         ren2->dst_entry->processed = 1;
871                         ren2->processed = 1;
872                         if (strcmp(ren1_dst, ren2_dst) != 0) {
873                                 clean_merge = 0;
874                                 output(o, 1, "CONFLICT (rename/rename): "
875                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
876                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
877                                        src, ren1_dst, branch1,
878                                        src, ren2_dst, branch2,
879                                        o->call_depth ? " (left unresolved)": "");
880                                 if (o->call_depth) {
881                                         remove_file_from_cache(src);
882                                         update_file(o, 0, ren1->pair->one->sha1,
883                                                     ren1->pair->one->mode, src);
884                                 }
885                                 conflict_rename_rename(o, ren1, branch1, ren2, branch2);
886                         } else {
887                                 struct merge_file_info mfi;
888                                 remove_file(o, 1, ren1_src, 1);
889                                 mfi = merge_file(o,
890                                                  ren1->pair->one,
891                                                  ren1->pair->two,
892                                                  ren2->pair->two,
893                                                  branch1,
894                                                  branch2);
895                                 if (mfi.merge || !mfi.clean)
896                                         output(o, 1, "Renaming %s->%s", src, ren1_dst);
897
898                                 if (mfi.merge)
899                                         output(o, 2, "Auto-merging %s", ren1_dst);
900
901                                 if (!mfi.clean) {
902                                         output(o, 1, "CONFLICT (content): merge conflict in %s",
903                                                ren1_dst);
904                                         clean_merge = 0;
905
906                                         if (!o->call_depth)
907                                                 update_stages(ren1_dst,
908                                                               ren1->pair->one,
909                                                               ren1->pair->two,
910                                                               ren2->pair->two,
911                                                               1 /* clear */);
912                                 }
913                                 update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
914                         }
915                 } else {
916                         /* Renamed in 1, maybe changed in 2 */
917                         struct string_list_item *item;
918                         /* we only use sha1 and mode of these */
919                         struct diff_filespec src_other, dst_other;
920                         int try_merge, stage = a_renames == renames1 ? 3: 2;
921
922                         remove_file(o, 1, ren1_src, o->call_depth || stage == 3);
923
924                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
925                         src_other.mode = ren1->src_entry->stages[stage].mode;
926                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
927                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
928
929                         try_merge = 0;
930
931                         if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
932                                 clean_merge = 0;
933                                 output(o, 1, "CONFLICT (rename/directory): Rename %s->%s in %s "
934                                        " directory %s added in %s",
935                                        ren1_src, ren1_dst, branch1,
936                                        ren1_dst, branch2);
937                                 conflict_rename_dir(o, ren1, branch1);
938                         } else if (sha_eq(src_other.sha1, null_sha1)) {
939                                 clean_merge = 0;
940                                 output(o, 1, "CONFLICT (rename/delete): Rename %s->%s in %s "
941                                        "and deleted in %s",
942                                        ren1_src, ren1_dst, branch1,
943                                        branch2);
944                                 update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
945                                 if (!o->call_depth)
946                                         update_stages(ren1_dst, NULL,
947                                                         branch1 == o->branch1 ?
948                                                         ren1->pair->two : NULL,
949                                                         branch1 == o->branch1 ?
950                                                         NULL : ren1->pair->two, 1);
951                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
952                                 const char *new_path;
953                                 clean_merge = 0;
954                                 try_merge = 1;
955                                 output(o, 1, "CONFLICT (rename/add): Rename %s->%s in %s. "
956                                        "%s added in %s",
957                                        ren1_src, ren1_dst, branch1,
958                                        ren1_dst, branch2);
959                                 if (o->call_depth) {
960                                         struct merge_file_info mfi;
961                                         struct diff_filespec one, a, b;
962
963                                         one.path = a.path = b.path =
964                                                 (char *)ren1_dst;
965                                         hashcpy(one.sha1, null_sha1);
966                                         one.mode = 0;
967                                         hashcpy(a.sha1, ren1->pair->two->sha1);
968                                         a.mode = ren1->pair->two->mode;
969                                         hashcpy(b.sha1, dst_other.sha1);
970                                         b.mode = dst_other.mode;
971                                         mfi = merge_file(o, &one, &a, &b,
972                                                          branch1,
973                                                          branch2);
974                                         output(o, 1, "Adding merged %s", ren1_dst);
975                                         update_file(o, 0,
976                                                     mfi.sha,
977                                                     mfi.mode,
978                                                     ren1_dst);
979                                 } else {
980                                         new_path = unique_path(o, ren1_dst, branch2);
981                                         output(o, 1, "Adding as %s instead", new_path);
982                                         update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
983                                 }
984                         } else if ((item = string_list_lookup(ren1_dst, renames2Dst))) {
985                                 ren2 = item->util;
986                                 clean_merge = 0;
987                                 ren2->processed = 1;
988                                 output(o, 1, "CONFLICT (rename/rename): "
989                                        "Rename %s->%s in %s. "
990                                        "Rename %s->%s in %s",
991                                        ren1_src, ren1_dst, branch1,
992                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
993                                 conflict_rename_rename_2(o, ren1, branch1, ren2, branch2);
994                         } else
995                                 try_merge = 1;
996
997                         if (try_merge) {
998                                 struct diff_filespec *one, *a, *b;
999                                 struct merge_file_info mfi;
1000                                 src_other.path = (char *)ren1_src;
1001
1002                                 one = ren1->pair->one;
1003                                 if (a_renames == renames1) {
1004                                         a = ren1->pair->two;
1005                                         b = &src_other;
1006                                 } else {
1007                                         b = ren1->pair->two;
1008                                         a = &src_other;
1009                                 }
1010                                 mfi = merge_file(o, one, a, b,
1011                                                 o->branch1, o->branch2);
1012
1013                                 if (mfi.clean &&
1014                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
1015                                     mfi.mode == ren1->pair->two->mode)
1016                                         /*
1017                                          * This messaged is part of
1018                                          * t6022 test. If you change
1019                                          * it update the test too.
1020                                          */
1021                                         output(o, 3, "Skipped %s (merged same as existing)", ren1_dst);
1022                                 else {
1023                                         if (mfi.merge || !mfi.clean)
1024                                                 output(o, 1, "Renaming %s => %s", ren1_src, ren1_dst);
1025                                         if (mfi.merge)
1026                                                 output(o, 2, "Auto-merging %s", ren1_dst);
1027                                         if (!mfi.clean) {
1028                                                 output(o, 1, "CONFLICT (rename/modify): Merge conflict in %s",
1029                                                        ren1_dst);
1030                                                 clean_merge = 0;
1031
1032                                                 if (!o->call_depth)
1033                                                         update_stages(ren1_dst,
1034                                                                       one, a, b, 1);
1035                                         }
1036                                         update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1037                                 }
1038                         }
1039                 }
1040         }
1041         string_list_clear(&a_by_dst, 0);
1042         string_list_clear(&b_by_dst, 0);
1043
1044         return clean_merge;
1045 }
1046
1047 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1048 {
1049         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1050 }
1051
1052 /* Per entry merge function */
1053 static int process_entry(struct merge_options *o,
1054                          const char *path, struct stage_data *entry)
1055 {
1056         /*
1057         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1058         print_index_entry("\tpath: ", entry);
1059         */
1060         int clean_merge = 1;
1061         unsigned o_mode = entry->stages[1].mode;
1062         unsigned a_mode = entry->stages[2].mode;
1063         unsigned b_mode = entry->stages[3].mode;
1064         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1065         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1066         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1067
1068         if (o_sha && (!a_sha || !b_sha)) {
1069                 /* Case A: Deleted in one */
1070                 if ((!a_sha && !b_sha) ||
1071                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1072                     (!a_sha && sha_eq(b_sha, o_sha))) {
1073                         /* Deleted in both or deleted in one and
1074                          * unchanged in the other */
1075                         if (a_sha)
1076                                 output(o, 2, "Removing %s", path);
1077                         /* do not touch working file if it did not exist */
1078                         remove_file(o, 1, path, !a_sha);
1079                 } else {
1080                         /* Deleted in one and changed in the other */
1081                         clean_merge = 0;
1082                         if (!a_sha) {
1083                                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1084                                        "and modified in %s. Version %s of %s left in tree.",
1085                                        path, o->branch1,
1086                                        o->branch2, o->branch2, path);
1087                                 update_file(o, 0, b_sha, b_mode, path);
1088                         } else {
1089                                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1090                                        "and modified in %s. Version %s of %s left in tree.",
1091                                        path, o->branch2,
1092                                        o->branch1, o->branch1, path);
1093                                 update_file(o, 0, a_sha, a_mode, path);
1094                         }
1095                 }
1096
1097         } else if ((!o_sha && a_sha && !b_sha) ||
1098                    (!o_sha && !a_sha && b_sha)) {
1099                 /* Case B: Added in one. */
1100                 const char *add_branch;
1101                 const char *other_branch;
1102                 unsigned mode;
1103                 const unsigned char *sha;
1104                 const char *conf;
1105
1106                 if (a_sha) {
1107                         add_branch = o->branch1;
1108                         other_branch = o->branch2;
1109                         mode = a_mode;
1110                         sha = a_sha;
1111                         conf = "file/directory";
1112                 } else {
1113                         add_branch = o->branch2;
1114                         other_branch = o->branch1;
1115                         mode = b_mode;
1116                         sha = b_sha;
1117                         conf = "directory/file";
1118                 }
1119                 if (string_list_has_string(&o->current_directory_set, path)) {
1120                         const char *new_path = unique_path(o, path, add_branch);
1121                         clean_merge = 0;
1122                         output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
1123                                "Adding %s as %s",
1124                                conf, path, other_branch, path, new_path);
1125                         remove_file(o, 0, path, 0);
1126                         update_file(o, 0, sha, mode, new_path);
1127                 } else {
1128                         output(o, 2, "Adding %s", path);
1129                         update_file(o, 1, sha, mode, path);
1130                 }
1131         } else if (a_sha && b_sha) {
1132                 /* Case C: Added in both (check for same permissions) and */
1133                 /* case D: Modified in both, but differently. */
1134                 const char *reason = "content";
1135                 struct merge_file_info mfi;
1136                 struct diff_filespec one, a, b;
1137
1138                 if (!o_sha) {
1139                         reason = "add/add";
1140                         o_sha = (unsigned char *)null_sha1;
1141                 }
1142                 output(o, 2, "Auto-merging %s", path);
1143                 one.path = a.path = b.path = (char *)path;
1144                 hashcpy(one.sha1, o_sha);
1145                 one.mode = o_mode;
1146                 hashcpy(a.sha1, a_sha);
1147                 a.mode = a_mode;
1148                 hashcpy(b.sha1, b_sha);
1149                 b.mode = b_mode;
1150
1151                 mfi = merge_file(o, &one, &a, &b,
1152                                  o->branch1, o->branch2);
1153
1154                 clean_merge = mfi.clean;
1155                 if (!mfi.clean) {
1156                         if (S_ISGITLINK(mfi.mode))
1157                                 reason = "submodule";
1158                         output(o, 1, "CONFLICT (%s): Merge conflict in %s",
1159                                         reason, path);
1160                 }
1161                 update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
1162         } else if (!o_sha && !a_sha && !b_sha) {
1163                 /*
1164                  * this entry was deleted altogether. a_mode == 0 means
1165                  * we had that path and want to actively remove it.
1166                  */
1167                 remove_file(o, 1, path, !a_mode);
1168         } else
1169                 die("Fatal merge failure, shouldn't happen.");
1170
1171         return clean_merge;
1172 }
1173
1174 struct unpack_trees_error_msgs get_porcelain_error_msgs(void)
1175 {
1176         struct unpack_trees_error_msgs msgs = {
1177                 /* would_overwrite */
1178                 "Your local changes to '%s' would be overwritten by merge.  Aborting.",
1179                 /* not_uptodate_file */
1180                 "Your local changes to '%s' would be overwritten by merge.  Aborting.",
1181                 /* not_uptodate_dir */
1182                 "Updating '%s' would lose untracked files in it.  Aborting.",
1183                 /* would_lose_untracked */
1184                 "Untracked working tree file '%s' would be %s by merge.  Aborting",
1185                 /* bind_overlap -- will not happen here */
1186                 NULL,
1187         };
1188         if (advice_commit_before_merge) {
1189                 msgs.would_overwrite = msgs.not_uptodate_file =
1190                         "Your local changes to '%s' would be overwritten by merge.  Aborting.\n"
1191                         "Please, commit your changes or stash them before you can merge.";
1192         }
1193         return msgs;
1194 }
1195
1196 int merge_trees(struct merge_options *o,
1197                 struct tree *head,
1198                 struct tree *merge,
1199                 struct tree *common,
1200                 struct tree **result)
1201 {
1202         int code, clean;
1203
1204         if (o->subtree_merge) {
1205                 merge = shift_tree_object(head, merge);
1206                 common = shift_tree_object(head, common);
1207         }
1208
1209         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1210                 output(o, 0, "Already uptodate!");
1211                 *result = head;
1212                 return 1;
1213         }
1214
1215         code = git_merge_trees(o->call_depth, common, head, merge);
1216
1217         if (code != 0) {
1218                 if (show(o, 4) || o->call_depth)
1219                         die("merging of trees %s and %s failed",
1220                             sha1_to_hex(head->object.sha1),
1221                             sha1_to_hex(merge->object.sha1));
1222                 else
1223                         exit(128);
1224         }
1225
1226         if (unmerged_cache()) {
1227                 struct string_list *entries, *re_head, *re_merge;
1228                 int i;
1229                 string_list_clear(&o->current_file_set, 1);
1230                 string_list_clear(&o->current_directory_set, 1);
1231                 get_files_dirs(o, head);
1232                 get_files_dirs(o, merge);
1233
1234                 entries = get_unmerged();
1235                 re_head  = get_renames(o, head, common, head, merge, entries);
1236                 re_merge = get_renames(o, merge, common, head, merge, entries);
1237                 clean = process_renames(o, re_head, re_merge);
1238                 for (i = 0; i < entries->nr; i++) {
1239                         const char *path = entries->items[i].string;
1240                         struct stage_data *e = entries->items[i].util;
1241                         if (!e->processed
1242                                 && !process_entry(o, path, e))
1243                                 clean = 0;
1244                 }
1245
1246                 string_list_clear(re_merge, 0);
1247                 string_list_clear(re_head, 0);
1248                 string_list_clear(entries, 1);
1249
1250         }
1251         else
1252                 clean = 1;
1253
1254         if (o->call_depth)
1255                 *result = write_tree_from_memory(o);
1256
1257         return clean;
1258 }
1259
1260 static struct commit_list *reverse_commit_list(struct commit_list *list)
1261 {
1262         struct commit_list *next = NULL, *current, *backup;
1263         for (current = list; current; current = backup) {
1264                 backup = current->next;
1265                 current->next = next;
1266                 next = current;
1267         }
1268         return next;
1269 }
1270
1271 /*
1272  * Merge the commits h1 and h2, return the resulting virtual
1273  * commit object and a flag indicating the cleanness of the merge.
1274  */
1275 int merge_recursive(struct merge_options *o,
1276                     struct commit *h1,
1277                     struct commit *h2,
1278                     struct commit_list *ca,
1279                     struct commit **result)
1280 {
1281         struct commit_list *iter;
1282         struct commit *merged_common_ancestors;
1283         struct tree *mrtree = mrtree;
1284         int clean;
1285
1286         if (show(o, 4)) {
1287                 output(o, 4, "Merging:");
1288                 output_commit_title(o, h1);
1289                 output_commit_title(o, h2);
1290         }
1291
1292         if (!ca) {
1293                 ca = get_merge_bases(h1, h2, 1);
1294                 ca = reverse_commit_list(ca);
1295         }
1296
1297         if (show(o, 5)) {
1298                 output(o, 5, "found %u common ancestor(s):", commit_list_count(ca));
1299                 for (iter = ca; iter; iter = iter->next)
1300                         output_commit_title(o, iter->item);
1301         }
1302
1303         merged_common_ancestors = pop_commit(&ca);
1304         if (merged_common_ancestors == NULL) {
1305                 /* if there is no common ancestor, make an empty tree */
1306                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1307
1308                 tree->object.parsed = 1;
1309                 tree->object.type = OBJ_TREE;
1310                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1311                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1312         }
1313
1314         for (iter = ca; iter; iter = iter->next) {
1315                 const char *saved_b1, *saved_b2;
1316                 o->call_depth++;
1317                 /*
1318                  * When the merge fails, the result contains files
1319                  * with conflict markers. The cleanness flag is
1320                  * ignored, it was never actually used, as result of
1321                  * merge_trees has always overwritten it: the committed
1322                  * "conflicts" were already resolved.
1323                  */
1324                 discard_cache();
1325                 saved_b1 = o->branch1;
1326                 saved_b2 = o->branch2;
1327                 o->branch1 = "Temporary merge branch 1";
1328                 o->branch2 = "Temporary merge branch 2";
1329                 merge_recursive(o, merged_common_ancestors, iter->item,
1330                                 NULL, &merged_common_ancestors);
1331                 o->branch1 = saved_b1;
1332                 o->branch2 = saved_b2;
1333                 o->call_depth--;
1334
1335                 if (!merged_common_ancestors)
1336                         die("merge returned no commit");
1337         }
1338
1339         discard_cache();
1340         if (!o->call_depth)
1341                 read_cache();
1342
1343         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
1344                             &mrtree);
1345
1346         if (o->call_depth) {
1347                 *result = make_virtual_commit(mrtree, "merged tree");
1348                 commit_list_insert(h1, &(*result)->parents);
1349                 commit_list_insert(h2, &(*result)->parents->next);
1350         }
1351         flush_output(o);
1352         return clean;
1353 }
1354
1355 static struct commit *get_ref(const unsigned char *sha1, const char *name)
1356 {
1357         struct object *object;
1358
1359         object = deref_tag(parse_object(sha1), name, strlen(name));
1360         if (!object)
1361                 return NULL;
1362         if (object->type == OBJ_TREE)
1363                 return make_virtual_commit((struct tree*)object, name);
1364         if (object->type != OBJ_COMMIT)
1365                 return NULL;
1366         if (parse_commit((struct commit *)object))
1367                 return NULL;
1368         return (struct commit *)object;
1369 }
1370
1371 int merge_recursive_generic(struct merge_options *o,
1372                             const unsigned char *head,
1373                             const unsigned char *merge,
1374                             int num_base_list,
1375                             const unsigned char **base_list,
1376                             struct commit **result)
1377 {
1378         int clean, index_fd;
1379         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1380         struct commit *head_commit = get_ref(head, o->branch1);
1381         struct commit *next_commit = get_ref(merge, o->branch2);
1382         struct commit_list *ca = NULL;
1383
1384         if (base_list) {
1385                 int i;
1386                 for (i = 0; i < num_base_list; ++i) {
1387                         struct commit *base;
1388                         if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
1389                                 return error("Could not parse object '%s'",
1390                                         sha1_to_hex(base_list[i]));
1391                         commit_list_insert(base, &ca);
1392                 }
1393         }
1394
1395         index_fd = hold_locked_index(lock, 1);
1396         clean = merge_recursive(o, head_commit, next_commit, ca,
1397                         result);
1398         if (active_cache_changed &&
1399                         (write_cache(index_fd, active_cache, active_nr) ||
1400                          commit_locked_index(lock)))
1401                 return error("Unable to write index.");
1402
1403         return clean ? 0 : 1;
1404 }
1405
1406 static int merge_recursive_config(const char *var, const char *value, void *cb)
1407 {
1408         struct merge_options *o = cb;
1409         if (!strcasecmp(var, "merge.verbosity")) {
1410                 o->verbosity = git_config_int(var, value);
1411                 return 0;
1412         }
1413         if (!strcasecmp(var, "diff.renamelimit")) {
1414                 o->diff_rename_limit = git_config_int(var, value);
1415                 return 0;
1416         }
1417         if (!strcasecmp(var, "merge.renamelimit")) {
1418                 o->merge_rename_limit = git_config_int(var, value);
1419                 return 0;
1420         }
1421         return git_xmerge_config(var, value, cb);
1422 }
1423
1424 void init_merge_options(struct merge_options *o)
1425 {
1426         memset(o, 0, sizeof(struct merge_options));
1427         o->verbosity = 2;
1428         o->buffer_output = 1;
1429         o->diff_rename_limit = -1;
1430         o->merge_rename_limit = -1;
1431         git_config(merge_recursive_config, o);
1432         if (getenv("GIT_MERGE_VERBOSITY"))
1433                 o->verbosity =
1434                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1435         if (o->verbosity >= 5)
1436                 o->buffer_output = 0;
1437         strbuf_init(&o->obuf, 0);
1438         memset(&o->current_file_set, 0, sizeof(struct string_list));
1439         o->current_file_set.strdup_strings = 1;
1440         memset(&o->current_directory_set, 0, sizeof(struct string_list));
1441         o->current_directory_set.strdup_strings = 1;
1442 }