Merge branch 'maint'
[git] / builtin-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 "cache-tree.h"
8 #include "commit.h"
9 #include "blob.h"
10 #include "builtin.h"
11 #include "tree-walk.h"
12 #include "diff.h"
13 #include "diffcore.h"
14 #include "run-command.h"
15 #include "tag.h"
16 #include "unpack-trees.h"
17 #include "path-list.h"
18 #include "xdiff-interface.h"
19 #include "interpolate.h"
20 #include "attr.h"
21 #include "merge-recursive.h"
22
23 static int subtree_merge;
24
25 static struct tree *shift_tree_object(struct tree *one, struct tree *two)
26 {
27         unsigned char shifted[20];
28
29         /*
30          * NEEDSWORK: this limits the recursion depth to hardcoded
31          * value '2' to avoid excessive overhead.
32          */
33         shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
34         if (!hashcmp(two->object.sha1, shifted))
35                 return two;
36         return lookup_tree(shifted);
37 }
38
39 /*
40  * A virtual commit has
41  * - (const char *)commit->util set to the name, and
42  * - *(int *)commit->object.sha1 set to the virtual id.
43  */
44
45 static unsigned commit_list_count(const struct commit_list *l)
46 {
47         unsigned c = 0;
48         for (; l; l = l->next )
49                 c++;
50         return c;
51 }
52
53 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
54 {
55         struct commit *commit = xcalloc(1, sizeof(struct commit));
56         static unsigned virtual_id = 1;
57         commit->tree = tree;
58         commit->util = (void*)comment;
59         *(int*)commit->object.sha1 = virtual_id++;
60         /* avoid warnings */
61         commit->object.parsed = 1;
62         return commit;
63 }
64
65 /*
66  * Since we use get_tree_entry(), which does not put the read object into
67  * the object pool, we cannot rely on a == b.
68  */
69 static int sha_eq(const unsigned char *a, const unsigned char *b)
70 {
71         if (!a && !b)
72                 return 2;
73         return a && b && hashcmp(a, b) == 0;
74 }
75
76 /*
77  * Since we want to write the index eventually, we cannot reuse the index
78  * for these (temporary) data.
79  */
80 struct stage_data
81 {
82         struct
83         {
84                 unsigned mode;
85                 unsigned char sha[20];
86         } stages[4];
87         unsigned processed:1;
88 };
89
90 static struct path_list current_file_set = {NULL, 0, 0, 1};
91 static struct path_list current_directory_set = {NULL, 0, 0, 1};
92
93 static int call_depth = 0;
94 static int verbosity = 2;
95 static int rename_limit = -1;
96 static int buffer_output = 1;
97 static struct strbuf obuf = STRBUF_INIT;
98
99 static int show(int v)
100 {
101         return (!call_depth && verbosity >= v) || verbosity >= 5;
102 }
103
104 static void flush_output(void)
105 {
106         if (obuf.len) {
107                 fputs(obuf.buf, stdout);
108                 strbuf_reset(&obuf);
109         }
110 }
111
112 static void output(int v, const char *fmt, ...)
113 {
114         int len;
115         va_list ap;
116
117         if (!show(v))
118                 return;
119
120         strbuf_grow(&obuf, call_depth * 2 + 2);
121         memset(obuf.buf + obuf.len, ' ', call_depth * 2);
122         strbuf_setlen(&obuf, obuf.len + call_depth * 2);
123
124         va_start(ap, fmt);
125         len = vsnprintf(obuf.buf + obuf.len, strbuf_avail(&obuf), fmt, ap);
126         va_end(ap);
127
128         if (len < 0)
129                 len = 0;
130         if (len >= strbuf_avail(&obuf)) {
131                 strbuf_grow(&obuf, len + 2);
132                 va_start(ap, fmt);
133                 len = vsnprintf(obuf.buf + obuf.len, strbuf_avail(&obuf), fmt, ap);
134                 va_end(ap);
135                 if (len >= strbuf_avail(&obuf)) {
136                         die("this should not happen, your snprintf is broken");
137                 }
138         }
139         strbuf_setlen(&obuf, obuf.len + len);
140         strbuf_add(&obuf, "\n", 1);
141         if (!buffer_output)
142                 flush_output();
143 }
144
145 static void output_commit_title(struct commit *commit)
146 {
147         int i;
148         flush_output();
149         for (i = call_depth; i--;)
150                 fputs("  ", stdout);
151         if (commit->util)
152                 printf("virtual %s\n", (char *)commit->util);
153         else {
154                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
155                 if (parse_commit(commit) != 0)
156                         printf("(bad commit)\n");
157                 else {
158                         const char *s;
159                         int len;
160                         for (s = commit->buffer; *s; s++)
161                                 if (*s == '\n' && s[1] == '\n') {
162                                         s += 2;
163                                         break;
164                                 }
165                         for (len = 0; s[len] && '\n' != s[len]; len++)
166                                 ; /* do nothing */
167                         printf("%.*s\n", len, s);
168                 }
169         }
170 }
171
172 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
173                 const char *path, int stage, int refresh, int options)
174 {
175         struct cache_entry *ce;
176         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
177         if (!ce)
178                 return error("addinfo_cache failed for path '%s'", path);
179         return add_cache_entry(ce, options);
180 }
181
182 /*
183  * This is a global variable which is used in a number of places but
184  * only written to in the 'merge' function.
185  *
186  * index_only == 1    => Don't leave any non-stage 0 entries in the cache and
187  *                       don't update the working directory.
188  *               0    => Leave unmerged entries in the cache and update
189  *                       the working directory.
190  */
191 static int index_only = 0;
192
193 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
194 {
195         parse_tree(tree);
196         init_tree_desc(desc, tree->buffer, tree->size);
197 }
198
199 static int git_merge_trees(int index_only,
200                            struct tree *common,
201                            struct tree *head,
202                            struct tree *merge)
203 {
204         int rc;
205         struct tree_desc t[3];
206         struct unpack_trees_options opts;
207
208         memset(&opts, 0, sizeof(opts));
209         if (index_only)
210                 opts.index_only = 1;
211         else
212                 opts.update = 1;
213         opts.merge = 1;
214         opts.head_idx = 2;
215         opts.fn = threeway_merge;
216
217         init_tree_desc_from_tree(t+0, common);
218         init_tree_desc_from_tree(t+1, head);
219         init_tree_desc_from_tree(t+2, merge);
220
221         rc = unpack_trees(3, t, &opts);
222         cache_tree_free(&active_cache_tree);
223         return rc;
224 }
225
226 struct tree *write_tree_from_memory(void)
227 {
228         struct tree *result = NULL;
229
230         if (unmerged_cache()) {
231                 int i;
232                 output(0, "There are unmerged index entries:");
233                 for (i = 0; i < active_nr; i++) {
234                         struct cache_entry *ce = active_cache[i];
235                         if (ce_stage(ce))
236                                 output(0, "%d %.*s", ce_stage(ce), ce_namelen(ce), ce->name);
237                 }
238                 return NULL;
239         }
240
241         if (!active_cache_tree)
242                 active_cache_tree = cache_tree();
243
244         if (!cache_tree_fully_valid(active_cache_tree) &&
245             cache_tree_update(active_cache_tree,
246                               active_cache, active_nr, 0, 0) < 0)
247                 die("error building trees");
248
249         result = lookup_tree(active_cache_tree->sha1);
250
251         return result;
252 }
253
254 static int save_files_dirs(const unsigned char *sha1,
255                 const char *base, int baselen, const char *path,
256                 unsigned int mode, int stage)
257 {
258         int len = strlen(path);
259         char *newpath = xmalloc(baselen + len + 1);
260         memcpy(newpath, base, baselen);
261         memcpy(newpath + baselen, path, len);
262         newpath[baselen + len] = '\0';
263
264         if (S_ISDIR(mode))
265                 path_list_insert(newpath, &current_directory_set);
266         else
267                 path_list_insert(newpath, &current_file_set);
268         free(newpath);
269
270         return READ_TREE_RECURSIVE;
271 }
272
273 static int get_files_dirs(struct tree *tree)
274 {
275         int n;
276         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs) != 0)
277                 return 0;
278         n = current_file_set.nr + current_directory_set.nr;
279         return n;
280 }
281
282 /*
283  * Returns an index_entry instance which doesn't have to correspond to
284  * a real cache entry in Git's index.
285  */
286 static struct stage_data *insert_stage_data(const char *path,
287                 struct tree *o, struct tree *a, struct tree *b,
288                 struct path_list *entries)
289 {
290         struct path_list_item *item;
291         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
292         get_tree_entry(o->object.sha1, path,
293                         e->stages[1].sha, &e->stages[1].mode);
294         get_tree_entry(a->object.sha1, path,
295                         e->stages[2].sha, &e->stages[2].mode);
296         get_tree_entry(b->object.sha1, path,
297                         e->stages[3].sha, &e->stages[3].mode);
298         item = path_list_insert(path, entries);
299         item->util = e;
300         return e;
301 }
302
303 /*
304  * Create a dictionary mapping file names to stage_data objects. The
305  * dictionary contains one entry for every path with a non-zero stage entry.
306  */
307 static struct path_list *get_unmerged(void)
308 {
309         struct path_list *unmerged = xcalloc(1, sizeof(struct path_list));
310         int i;
311
312         unmerged->strdup_paths = 1;
313
314         for (i = 0; i < active_nr; i++) {
315                 struct path_list_item *item;
316                 struct stage_data *e;
317                 struct cache_entry *ce = active_cache[i];
318                 if (!ce_stage(ce))
319                         continue;
320
321                 item = path_list_lookup(ce->name, unmerged);
322                 if (!item) {
323                         item = path_list_insert(ce->name, unmerged);
324                         item->util = xcalloc(1, sizeof(struct stage_data));
325                 }
326                 e = item->util;
327                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
328                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
329         }
330
331         return unmerged;
332 }
333
334 struct rename
335 {
336         struct diff_filepair *pair;
337         struct stage_data *src_entry;
338         struct stage_data *dst_entry;
339         unsigned processed:1;
340 };
341
342 /*
343  * Get information of all renames which occurred between 'o_tree' and
344  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
345  * 'b_tree') to be able to associate the correct cache entries with
346  * the rename information. 'tree' is always equal to either a_tree or b_tree.
347  */
348 static struct path_list *get_renames(struct tree *tree,
349                                         struct tree *o_tree,
350                                         struct tree *a_tree,
351                                         struct tree *b_tree,
352                                         struct path_list *entries)
353 {
354         int i;
355         struct path_list *renames;
356         struct diff_options opts;
357
358         renames = xcalloc(1, sizeof(struct path_list));
359         diff_setup(&opts);
360         DIFF_OPT_SET(&opts, RECURSIVE);
361         opts.detect_rename = DIFF_DETECT_RENAME;
362         opts.rename_limit = rename_limit;
363         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
364         if (diff_setup_done(&opts) < 0)
365                 die("diff setup failed");
366         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
367         diffcore_std(&opts);
368         for (i = 0; i < diff_queued_diff.nr; ++i) {
369                 struct path_list_item *item;
370                 struct rename *re;
371                 struct diff_filepair *pair = diff_queued_diff.queue[i];
372                 if (pair->status != 'R') {
373                         diff_free_filepair(pair);
374                         continue;
375                 }
376                 re = xmalloc(sizeof(*re));
377                 re->processed = 0;
378                 re->pair = pair;
379                 item = path_list_lookup(re->pair->one->path, entries);
380                 if (!item)
381                         re->src_entry = insert_stage_data(re->pair->one->path,
382                                         o_tree, a_tree, b_tree, entries);
383                 else
384                         re->src_entry = item->util;
385
386                 item = path_list_lookup(re->pair->two->path, entries);
387                 if (!item)
388                         re->dst_entry = insert_stage_data(re->pair->two->path,
389                                         o_tree, a_tree, b_tree, entries);
390                 else
391                         re->dst_entry = item->util;
392                 item = path_list_insert(pair->one->path, renames);
393                 item->util = re;
394         }
395         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
396         diff_queued_diff.nr = 0;
397         diff_flush(&opts);
398         return renames;
399 }
400
401 static int update_stages(const char *path, struct diff_filespec *o,
402                          struct diff_filespec *a, struct diff_filespec *b,
403                          int clear)
404 {
405         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
406         if (clear)
407                 if (remove_file_from_cache(path))
408                         return -1;
409         if (o)
410                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
411                         return -1;
412         if (a)
413                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
414                         return -1;
415         if (b)
416                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
417                         return -1;
418         return 0;
419 }
420
421 static int remove_path(const char *name)
422 {
423         int ret;
424         char *slash, *dirs;
425
426         ret = unlink(name);
427         if (ret)
428                 return ret;
429         dirs = xstrdup(name);
430         while ((slash = strrchr(name, '/'))) {
431                 *slash = '\0';
432                 if (rmdir(name) != 0)
433                         break;
434         }
435         free(dirs);
436         return ret;
437 }
438
439 static int remove_file(int clean, const char *path, int no_wd)
440 {
441         int update_cache = index_only || clean;
442         int update_working_directory = !index_only && !no_wd;
443
444         if (update_cache) {
445                 if (remove_file_from_cache(path))
446                         return -1;
447         }
448         if (update_working_directory) {
449                 unlink(path);
450                 if (errno != ENOENT || errno != EISDIR)
451                         return -1;
452                 remove_path(path);
453         }
454         return 0;
455 }
456
457 static char *unique_path(const char *path, const char *branch)
458 {
459         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
460         int suffix = 0;
461         struct stat st;
462         char *p = newpath + strlen(path);
463         strcpy(newpath, path);
464         *(p++) = '~';
465         strcpy(p, branch);
466         for (; *p; ++p)
467                 if ('/' == *p)
468                         *p = '_';
469         while (path_list_has_path(&current_file_set, newpath) ||
470                path_list_has_path(&current_directory_set, newpath) ||
471                lstat(newpath, &st) == 0)
472                 sprintf(p, "_%d", suffix++);
473
474         path_list_insert(newpath, &current_file_set);
475         return newpath;
476 }
477
478 static int mkdir_p(const char *path, unsigned long mode)
479 {
480         /* path points to cache entries, so xstrdup before messing with it */
481         char *buf = xstrdup(path);
482         int result = safe_create_leading_directories(buf);
483         free(buf);
484         return result;
485 }
486
487 static void flush_buffer(int fd, const char *buf, unsigned long size)
488 {
489         while (size > 0) {
490                 long ret = write_in_full(fd, buf, size);
491                 if (ret < 0) {
492                         /* Ignore epipe */
493                         if (errno == EPIPE)
494                                 break;
495                         die("merge-recursive: %s", strerror(errno));
496                 } else if (!ret) {
497                         die("merge-recursive: disk full?");
498                 }
499                 size -= ret;
500                 buf += ret;
501         }
502 }
503
504 static int make_room_for_path(const char *path)
505 {
506         int status;
507         const char *msg = "failed to create path '%s'%s";
508
509         status = mkdir_p(path, 0777);
510         if (status) {
511                 if (status == -3) {
512                         /* something else exists */
513                         error(msg, path, ": perhaps a D/F conflict?");
514                         return -1;
515                 }
516                 die(msg, path, "");
517         }
518
519         /* Successful unlink is good.. */
520         if (!unlink(path))
521                 return 0;
522         /* .. and so is no existing file */
523         if (errno == ENOENT)
524                 return 0;
525         /* .. but not some other error (who really cares what?) */
526         return error(msg, path, ": perhaps a D/F conflict?");
527 }
528
529 static void update_file_flags(const unsigned char *sha,
530                               unsigned mode,
531                               const char *path,
532                               int update_cache,
533                               int update_wd)
534 {
535         if (index_only)
536                 update_wd = 0;
537
538         if (update_wd) {
539                 enum object_type type;
540                 void *buf;
541                 unsigned long size;
542
543                 if (S_ISGITLINK(mode))
544                         die("cannot read object %s '%s': It is a submodule!",
545                             sha1_to_hex(sha), path);
546
547                 buf = read_sha1_file(sha, &type, &size);
548                 if (!buf)
549                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
550                 if (type != OBJ_BLOB)
551                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
552
553                 if (make_room_for_path(path) < 0) {
554                         update_wd = 0;
555                         goto update_index;
556                 }
557                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
558                         int fd;
559                         if (mode & 0100)
560                                 mode = 0777;
561                         else
562                                 mode = 0666;
563                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
564                         if (fd < 0)
565                                 die("failed to open %s: %s", path, strerror(errno));
566                         flush_buffer(fd, buf, size);
567                         close(fd);
568                 } else if (S_ISLNK(mode)) {
569                         char *lnk = xmemdupz(buf, size);
570                         mkdir_p(path, 0777);
571                         unlink(path);
572                         symlink(lnk, path);
573                         free(lnk);
574                 } else
575                         die("do not know what to do with %06o %s '%s'",
576                             mode, sha1_to_hex(sha), path);
577         }
578  update_index:
579         if (update_cache)
580                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
581 }
582
583 static void update_file(int clean,
584                         const unsigned char *sha,
585                         unsigned mode,
586                         const char *path)
587 {
588         update_file_flags(sha, mode, path, index_only || clean, !index_only);
589 }
590
591 /* Low level file merging, update and removal */
592
593 struct merge_file_info
594 {
595         unsigned char sha[20];
596         unsigned mode;
597         unsigned clean:1,
598                  merge:1;
599 };
600
601 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
602 {
603         unsigned long size;
604         enum object_type type;
605
606         if (!hashcmp(sha1, null_sha1)) {
607                 mm->ptr = xstrdup("");
608                 mm->size = 0;
609                 return;
610         }
611
612         mm->ptr = read_sha1_file(sha1, &type, &size);
613         if (!mm->ptr || type != OBJ_BLOB)
614                 die("unable to read blob object %s", sha1_to_hex(sha1));
615         mm->size = size;
616 }
617
618 /*
619  * Customizable low-level merge drivers support.
620  */
621
622 struct ll_merge_driver;
623 typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
624                            const char *path,
625                            mmfile_t *orig,
626                            mmfile_t *src1, const char *name1,
627                            mmfile_t *src2, const char *name2,
628                            mmbuffer_t *result);
629
630 struct ll_merge_driver {
631         const char *name;
632         const char *description;
633         ll_merge_fn fn;
634         const char *recursive;
635         struct ll_merge_driver *next;
636         char *cmdline;
637 };
638
639 /*
640  * Built-in low-levels
641  */
642 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
643                            const char *path_unused,
644                            mmfile_t *orig,
645                            mmfile_t *src1, const char *name1,
646                            mmfile_t *src2, const char *name2,
647                            mmbuffer_t *result)
648 {
649         /*
650          * The tentative merge result is "ours" for the final round,
651          * or common ancestor for an internal merge.  Still return
652          * "conflicted merge" status.
653          */
654         mmfile_t *stolen = index_only ? orig : src1;
655
656         result->ptr = stolen->ptr;
657         result->size = stolen->size;
658         stolen->ptr = NULL;
659         return 1;
660 }
661
662 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
663                         const char *path_unused,
664                         mmfile_t *orig,
665                         mmfile_t *src1, const char *name1,
666                         mmfile_t *src2, const char *name2,
667                         mmbuffer_t *result)
668 {
669         xpparam_t xpp;
670
671         if (buffer_is_binary(orig->ptr, orig->size) ||
672             buffer_is_binary(src1->ptr, src1->size) ||
673             buffer_is_binary(src2->ptr, src2->size)) {
674                 warning("Cannot merge binary files: %s vs. %s\n",
675                         name1, name2);
676                 return ll_binary_merge(drv_unused, path_unused,
677                                        orig, src1, name1,
678                                        src2, name2,
679                                        result);
680         }
681
682         memset(&xpp, 0, sizeof(xpp));
683         return xdl_merge(orig,
684                          src1, name1,
685                          src2, name2,
686                          &xpp, XDL_MERGE_ZEALOUS,
687                          result);
688 }
689
690 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
691                           const char *path_unused,
692                           mmfile_t *orig,
693                           mmfile_t *src1, const char *name1,
694                           mmfile_t *src2, const char *name2,
695                           mmbuffer_t *result)
696 {
697         char *src, *dst;
698         long size;
699         const int marker_size = 7;
700
701         int status = ll_xdl_merge(drv_unused, path_unused,
702                                   orig, src1, NULL, src2, NULL, result);
703         if (status <= 0)
704                 return status;
705         size = result->size;
706         src = dst = result->ptr;
707         while (size) {
708                 char ch;
709                 if ((marker_size < size) &&
710                     (*src == '<' || *src == '=' || *src == '>')) {
711                         int i;
712                         ch = *src;
713                         for (i = 0; i < marker_size; i++)
714                                 if (src[i] != ch)
715                                         goto not_a_marker;
716                         if (src[marker_size] != '\n')
717                                 goto not_a_marker;
718                         src += marker_size + 1;
719                         size -= marker_size + 1;
720                         continue;
721                 }
722         not_a_marker:
723                 do {
724                         ch = *src++;
725                         *dst++ = ch;
726                         size--;
727                 } while (ch != '\n' && size);
728         }
729         result->size = dst - result->ptr;
730         return 0;
731 }
732
733 #define LL_BINARY_MERGE 0
734 #define LL_TEXT_MERGE 1
735 #define LL_UNION_MERGE 2
736 static struct ll_merge_driver ll_merge_drv[] = {
737         { "binary", "built-in binary merge", ll_binary_merge },
738         { "text", "built-in 3-way text merge", ll_xdl_merge },
739         { "union", "built-in union merge", ll_union_merge },
740 };
741
742 static void create_temp(mmfile_t *src, char *path)
743 {
744         int fd;
745
746         strcpy(path, ".merge_file_XXXXXX");
747         fd = xmkstemp(path);
748         if (write_in_full(fd, src->ptr, src->size) != src->size)
749                 die("unable to write temp-file");
750         close(fd);
751 }
752
753 /*
754  * User defined low-level merge driver support.
755  */
756 static int ll_ext_merge(const struct ll_merge_driver *fn,
757                         const char *path,
758                         mmfile_t *orig,
759                         mmfile_t *src1, const char *name1,
760                         mmfile_t *src2, const char *name2,
761                         mmbuffer_t *result)
762 {
763         char temp[3][50];
764         char cmdbuf[2048];
765         struct interp table[] = {
766                 { "%O" },
767                 { "%A" },
768                 { "%B" },
769         };
770         struct child_process child;
771         const char *args[20];
772         int status, fd, i;
773         struct stat st;
774
775         if (fn->cmdline == NULL)
776                 die("custom merge driver %s lacks command line.", fn->name);
777
778         result->ptr = NULL;
779         result->size = 0;
780         create_temp(orig, temp[0]);
781         create_temp(src1, temp[1]);
782         create_temp(src2, temp[2]);
783
784         interp_set_entry(table, 0, temp[0]);
785         interp_set_entry(table, 1, temp[1]);
786         interp_set_entry(table, 2, temp[2]);
787
788         output(1, "merging %s using %s", path,
789                fn->description ? fn->description : fn->name);
790
791         interpolate(cmdbuf, sizeof(cmdbuf), fn->cmdline, table, 3);
792
793         memset(&child, 0, sizeof(child));
794         child.argv = args;
795         args[0] = "sh";
796         args[1] = "-c";
797         args[2] = cmdbuf;
798         args[3] = NULL;
799
800         status = run_command(&child);
801         if (status < -ERR_RUN_COMMAND_FORK)
802                 ; /* failure in run-command */
803         else
804                 status = -status;
805         fd = open(temp[1], O_RDONLY);
806         if (fd < 0)
807                 goto bad;
808         if (fstat(fd, &st))
809                 goto close_bad;
810         result->size = st.st_size;
811         result->ptr = xmalloc(result->size + 1);
812         if (read_in_full(fd, result->ptr, result->size) != result->size) {
813                 free(result->ptr);
814                 result->ptr = NULL;
815                 result->size = 0;
816         }
817  close_bad:
818         close(fd);
819  bad:
820         for (i = 0; i < 3; i++)
821                 unlink(temp[i]);
822         return status;
823 }
824
825 /*
826  * merge.default and merge.driver configuration items
827  */
828 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
829 static const char *default_ll_merge;
830
831 static int read_merge_config(const char *var, const char *value)
832 {
833         struct ll_merge_driver *fn;
834         const char *ep, *name;
835         int namelen;
836
837         if (!strcmp(var, "merge.default")) {
838                 if (!value)
839                         return config_error_nonbool(var);
840                 default_ll_merge = strdup(value);
841                 return 0;
842         }
843
844         /*
845          * We are not interested in anything but "merge.<name>.variable";
846          * especially, we do not want to look at variables such as
847          * "merge.summary", "merge.tool", and "merge.verbosity".
848          */
849         if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
850                 return 0;
851
852         /*
853          * Find existing one as we might be processing merge.<name>.var2
854          * after seeing merge.<name>.var1.
855          */
856         name = var + 6;
857         namelen = ep - name;
858         for (fn = ll_user_merge; fn; fn = fn->next)
859                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
860                         break;
861         if (!fn) {
862                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
863                 fn->name = xmemdupz(name, namelen);
864                 fn->fn = ll_ext_merge;
865                 *ll_user_merge_tail = fn;
866                 ll_user_merge_tail = &(fn->next);
867         }
868
869         ep++;
870
871         if (!strcmp("name", ep)) {
872                 if (!value)
873                         return config_error_nonbool(var);
874                 fn->description = strdup(value);
875                 return 0;
876         }
877
878         if (!strcmp("driver", ep)) {
879                 if (!value)
880                         return config_error_nonbool(var);
881                 /*
882                  * merge.<name>.driver specifies the command line:
883                  *
884                  *      command-line
885                  *
886                  * The command-line will be interpolated with the following
887                  * tokens and is given to the shell:
888                  *
889                  *    %O - temporary file name for the merge base.
890                  *    %A - temporary file name for our version.
891                  *    %B - temporary file name for the other branches' version.
892                  *
893                  * The external merge driver should write the results in the
894                  * file named by %A, and signal that it has done with zero exit
895                  * status.
896                  */
897                 fn->cmdline = strdup(value);
898                 return 0;
899         }
900
901         if (!strcmp("recursive", ep)) {
902                 if (!value)
903                         return config_error_nonbool(var);
904                 fn->recursive = strdup(value);
905                 return 0;
906         }
907
908         return 0;
909 }
910
911 static void initialize_ll_merge(void)
912 {
913         if (ll_user_merge_tail)
914                 return;
915         ll_user_merge_tail = &ll_user_merge;
916         git_config(read_merge_config);
917 }
918
919 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
920 {
921         struct ll_merge_driver *fn;
922         const char *name;
923         int i;
924
925         initialize_ll_merge();
926
927         if (ATTR_TRUE(merge_attr))
928                 return &ll_merge_drv[LL_TEXT_MERGE];
929         else if (ATTR_FALSE(merge_attr))
930                 return &ll_merge_drv[LL_BINARY_MERGE];
931         else if (ATTR_UNSET(merge_attr)) {
932                 if (!default_ll_merge)
933                         return &ll_merge_drv[LL_TEXT_MERGE];
934                 else
935                         name = default_ll_merge;
936         }
937         else
938                 name = merge_attr;
939
940         for (fn = ll_user_merge; fn; fn = fn->next)
941                 if (!strcmp(fn->name, name))
942                         return fn;
943
944         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
945                 if (!strcmp(ll_merge_drv[i].name, name))
946                         return &ll_merge_drv[i];
947
948         /* default to the 3-way */
949         return &ll_merge_drv[LL_TEXT_MERGE];
950 }
951
952 static const char *git_path_check_merge(const char *path)
953 {
954         static struct git_attr_check attr_merge_check;
955
956         if (!attr_merge_check.attr)
957                 attr_merge_check.attr = git_attr("merge", 5);
958
959         if (git_checkattr(path, 1, &attr_merge_check))
960                 return NULL;
961         return attr_merge_check.value;
962 }
963
964 static int ll_merge(mmbuffer_t *result_buf,
965                     struct diff_filespec *o,
966                     struct diff_filespec *a,
967                     struct diff_filespec *b,
968                     const char *branch1,
969                     const char *branch2)
970 {
971         mmfile_t orig, src1, src2;
972         char *name1, *name2;
973         int merge_status;
974         const char *ll_driver_name;
975         const struct ll_merge_driver *driver;
976
977         name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
978         name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
979
980         fill_mm(o->sha1, &orig);
981         fill_mm(a->sha1, &src1);
982         fill_mm(b->sha1, &src2);
983
984         ll_driver_name = git_path_check_merge(a->path);
985         driver = find_ll_merge_driver(ll_driver_name);
986
987         if (index_only && driver->recursive)
988                 driver = find_ll_merge_driver(driver->recursive);
989         merge_status = driver->fn(driver, a->path,
990                                   &orig, &src1, name1, &src2, name2,
991                                   result_buf);
992
993         free(name1);
994         free(name2);
995         free(orig.ptr);
996         free(src1.ptr);
997         free(src2.ptr);
998         return merge_status;
999 }
1000
1001 static struct merge_file_info merge_file(struct diff_filespec *o,
1002                 struct diff_filespec *a, struct diff_filespec *b,
1003                 const char *branch1, const char *branch2)
1004 {
1005         struct merge_file_info result;
1006         result.merge = 0;
1007         result.clean = 1;
1008
1009         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
1010                 result.clean = 0;
1011                 if (S_ISREG(a->mode)) {
1012                         result.mode = a->mode;
1013                         hashcpy(result.sha, a->sha1);
1014                 } else {
1015                         result.mode = b->mode;
1016                         hashcpy(result.sha, b->sha1);
1017                 }
1018         } else {
1019                 if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
1020                         result.merge = 1;
1021
1022                 result.mode = a->mode == o->mode ? b->mode: a->mode;
1023
1024                 if (sha_eq(a->sha1, o->sha1))
1025                         hashcpy(result.sha, b->sha1);
1026                 else if (sha_eq(b->sha1, o->sha1))
1027                         hashcpy(result.sha, a->sha1);
1028                 else if (S_ISREG(a->mode)) {
1029                         mmbuffer_t result_buf;
1030                         int merge_status;
1031
1032                         merge_status = ll_merge(&result_buf, o, a, b,
1033                                                 branch1, branch2);
1034
1035                         if ((merge_status < 0) || !result_buf.ptr)
1036                                 die("Failed to execute internal merge");
1037
1038                         if (write_sha1_file(result_buf.ptr, result_buf.size,
1039                                             blob_type, result.sha))
1040                                 die("Unable to add %s to database",
1041                                     a->path);
1042
1043                         free(result_buf.ptr);
1044                         result.clean = (merge_status == 0);
1045                 } else if (S_ISGITLINK(a->mode)) {
1046                         result.clean = 0;
1047                         hashcpy(result.sha, a->sha1);
1048                 } else if (S_ISLNK(a->mode)) {
1049                         hashcpy(result.sha, a->sha1);
1050
1051                         if (!sha_eq(a->sha1, b->sha1))
1052                                 result.clean = 0;
1053                 } else {
1054                         die("unsupported object type in the tree");
1055                 }
1056         }
1057
1058         return result;
1059 }
1060
1061 static void conflict_rename_rename(struct rename *ren1,
1062                                    const char *branch1,
1063                                    struct rename *ren2,
1064                                    const char *branch2)
1065 {
1066         char *del[2];
1067         int delp = 0;
1068         const char *ren1_dst = ren1->pair->two->path;
1069         const char *ren2_dst = ren2->pair->two->path;
1070         const char *dst_name1 = ren1_dst;
1071         const char *dst_name2 = ren2_dst;
1072         if (path_list_has_path(&current_directory_set, ren1_dst)) {
1073                 dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
1074                 output(1, "%s is a directory in %s added as %s instead",
1075                        ren1_dst, branch2, dst_name1);
1076                 remove_file(0, ren1_dst, 0);
1077         }
1078         if (path_list_has_path(&current_directory_set, ren2_dst)) {
1079                 dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
1080                 output(1, "%s is a directory in %s added as %s instead",
1081                        ren2_dst, branch1, dst_name2);
1082                 remove_file(0, ren2_dst, 0);
1083         }
1084         if (index_only) {
1085                 remove_file_from_cache(dst_name1);
1086                 remove_file_from_cache(dst_name2);
1087                 /*
1088                  * Uncomment to leave the conflicting names in the resulting tree
1089                  *
1090                  * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
1091                  * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
1092                  */
1093         } else {
1094                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
1095                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
1096         }
1097         while (delp--)
1098                 free(del[delp]);
1099 }
1100
1101 static void conflict_rename_dir(struct rename *ren1,
1102                                 const char *branch1)
1103 {
1104         char *new_path = unique_path(ren1->pair->two->path, branch1);
1105         output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
1106         remove_file(0, ren1->pair->two->path, 0);
1107         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
1108         free(new_path);
1109 }
1110
1111 static void conflict_rename_rename_2(struct rename *ren1,
1112                                      const char *branch1,
1113                                      struct rename *ren2,
1114                                      const char *branch2)
1115 {
1116         char *new_path1 = unique_path(ren1->pair->two->path, branch1);
1117         char *new_path2 = unique_path(ren2->pair->two->path, branch2);
1118         output(1, "Renamed %s to %s and %s to %s instead",
1119                ren1->pair->one->path, new_path1,
1120                ren2->pair->one->path, new_path2);
1121         remove_file(0, ren1->pair->two->path, 0);
1122         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
1123         update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
1124         free(new_path2);
1125         free(new_path1);
1126 }
1127
1128 static int process_renames(struct path_list *a_renames,
1129                            struct path_list *b_renames,
1130                            const char *a_branch,
1131                            const char *b_branch)
1132 {
1133         int clean_merge = 1, i, j;
1134         struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
1135         const struct rename *sre;
1136
1137         for (i = 0; i < a_renames->nr; i++) {
1138                 sre = a_renames->items[i].util;
1139                 path_list_insert(sre->pair->two->path, &a_by_dst)->util
1140                         = sre->dst_entry;
1141         }
1142         for (i = 0; i < b_renames->nr; i++) {
1143                 sre = b_renames->items[i].util;
1144                 path_list_insert(sre->pair->two->path, &b_by_dst)->util
1145                         = sre->dst_entry;
1146         }
1147
1148         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1149                 int compare;
1150                 char *src;
1151                 struct path_list *renames1, *renames2, *renames2Dst;
1152                 struct rename *ren1 = NULL, *ren2 = NULL;
1153                 const char *branch1, *branch2;
1154                 const char *ren1_src, *ren1_dst;
1155
1156                 if (i >= a_renames->nr) {
1157                         compare = 1;
1158                         ren2 = b_renames->items[j++].util;
1159                 } else if (j >= b_renames->nr) {
1160                         compare = -1;
1161                         ren1 = a_renames->items[i++].util;
1162                 } else {
1163                         compare = strcmp(a_renames->items[i].path,
1164                                         b_renames->items[j].path);
1165                         if (compare <= 0)
1166                                 ren1 = a_renames->items[i++].util;
1167                         if (compare >= 0)
1168                                 ren2 = b_renames->items[j++].util;
1169                 }
1170
1171                 /* TODO: refactor, so that 1/2 are not needed */
1172                 if (ren1) {
1173                         renames1 = a_renames;
1174                         renames2 = b_renames;
1175                         renames2Dst = &b_by_dst;
1176                         branch1 = a_branch;
1177                         branch2 = b_branch;
1178                 } else {
1179                         struct rename *tmp;
1180                         renames1 = b_renames;
1181                         renames2 = a_renames;
1182                         renames2Dst = &a_by_dst;
1183                         branch1 = b_branch;
1184                         branch2 = a_branch;
1185                         tmp = ren2;
1186                         ren2 = ren1;
1187                         ren1 = tmp;
1188                 }
1189                 src = ren1->pair->one->path;
1190
1191                 ren1->dst_entry->processed = 1;
1192                 ren1->src_entry->processed = 1;
1193
1194                 if (ren1->processed)
1195                         continue;
1196                 ren1->processed = 1;
1197
1198                 ren1_src = ren1->pair->one->path;
1199                 ren1_dst = ren1->pair->two->path;
1200
1201                 if (ren2) {
1202                         const char *ren2_src = ren2->pair->one->path;
1203                         const char *ren2_dst = ren2->pair->two->path;
1204                         /* Renamed in 1 and renamed in 2 */
1205                         if (strcmp(ren1_src, ren2_src) != 0)
1206                                 die("ren1.src != ren2.src");
1207                         ren2->dst_entry->processed = 1;
1208                         ren2->processed = 1;
1209                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1210                                 clean_merge = 0;
1211                                 output(1, "CONFLICT (rename/rename): "
1212                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
1213                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
1214                                        src, ren1_dst, branch1,
1215                                        src, ren2_dst, branch2,
1216                                        index_only ? " (left unresolved)": "");
1217                                 if (index_only) {
1218                                         remove_file_from_cache(src);
1219                                         update_file(0, ren1->pair->one->sha1,
1220                                                     ren1->pair->one->mode, src);
1221                                 }
1222                                 conflict_rename_rename(ren1, branch1, ren2, branch2);
1223                         } else {
1224                                 struct merge_file_info mfi;
1225                                 remove_file(1, ren1_src, 1);
1226                                 mfi = merge_file(ren1->pair->one,
1227                                                  ren1->pair->two,
1228                                                  ren2->pair->two,
1229                                                  branch1,
1230                                                  branch2);
1231                                 if (mfi.merge || !mfi.clean)
1232                                         output(1, "Renamed %s->%s", src, ren1_dst);
1233
1234                                 if (mfi.merge)
1235                                         output(2, "Auto-merged %s", ren1_dst);
1236
1237                                 if (!mfi.clean) {
1238                                         output(1, "CONFLICT (content): merge conflict in %s",
1239                                                ren1_dst);
1240                                         clean_merge = 0;
1241
1242                                         if (!index_only)
1243                                                 update_stages(ren1_dst,
1244                                                               ren1->pair->one,
1245                                                               ren1->pair->two,
1246                                                               ren2->pair->two,
1247                                                               1 /* clear */);
1248                                 }
1249                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1250                         }
1251                 } else {
1252                         /* Renamed in 1, maybe changed in 2 */
1253                         struct path_list_item *item;
1254                         /* we only use sha1 and mode of these */
1255                         struct diff_filespec src_other, dst_other;
1256                         int try_merge, stage = a_renames == renames1 ? 3: 2;
1257
1258                         remove_file(1, ren1_src, index_only || stage == 3);
1259
1260                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
1261                         src_other.mode = ren1->src_entry->stages[stage].mode;
1262                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
1263                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
1264
1265                         try_merge = 0;
1266
1267                         if (path_list_has_path(&current_directory_set, ren1_dst)) {
1268                                 clean_merge = 0;
1269                                 output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
1270                                        " directory %s added in %s",
1271                                        ren1_src, ren1_dst, branch1,
1272                                        ren1_dst, branch2);
1273                                 conflict_rename_dir(ren1, branch1);
1274                         } else if (sha_eq(src_other.sha1, null_sha1)) {
1275                                 clean_merge = 0;
1276                                 output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
1277                                        "and deleted in %s",
1278                                        ren1_src, ren1_dst, branch1,
1279                                        branch2);
1280                                 update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
1281                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
1282                                 const char *new_path;
1283                                 clean_merge = 0;
1284                                 try_merge = 1;
1285                                 output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
1286                                        "%s added in %s",
1287                                        ren1_src, ren1_dst, branch1,
1288                                        ren1_dst, branch2);
1289                                 new_path = unique_path(ren1_dst, branch2);
1290                                 output(1, "Added as %s instead", new_path);
1291                                 update_file(0, dst_other.sha1, dst_other.mode, new_path);
1292                         } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
1293                                 ren2 = item->util;
1294                                 clean_merge = 0;
1295                                 ren2->processed = 1;
1296                                 output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
1297                                        "Renamed %s->%s in %s",
1298                                        ren1_src, ren1_dst, branch1,
1299                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
1300                                 conflict_rename_rename_2(ren1, branch1, ren2, branch2);
1301                         } else
1302                                 try_merge = 1;
1303
1304                         if (try_merge) {
1305                                 struct diff_filespec *o, *a, *b;
1306                                 struct merge_file_info mfi;
1307                                 src_other.path = (char *)ren1_src;
1308
1309                                 o = ren1->pair->one;
1310                                 if (a_renames == renames1) {
1311                                         a = ren1->pair->two;
1312                                         b = &src_other;
1313                                 } else {
1314                                         b = ren1->pair->two;
1315                                         a = &src_other;
1316                                 }
1317                                 mfi = merge_file(o, a, b,
1318                                                 a_branch, b_branch);
1319
1320                                 if (mfi.clean &&
1321                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
1322                                     mfi.mode == ren1->pair->two->mode)
1323                                         /*
1324                                          * This messaged is part of
1325                                          * t6022 test. If you change
1326                                          * it update the test too.
1327                                          */
1328                                         output(3, "Skipped %s (merged same as existing)", ren1_dst);
1329                                 else {
1330                                         if (mfi.merge || !mfi.clean)
1331                                                 output(1, "Renamed %s => %s", ren1_src, ren1_dst);
1332                                         if (mfi.merge)
1333                                                 output(2, "Auto-merged %s", ren1_dst);
1334                                         if (!mfi.clean) {
1335                                                 output(1, "CONFLICT (rename/modify): Merge conflict in %s",
1336                                                        ren1_dst);
1337                                                 clean_merge = 0;
1338
1339                                                 if (!index_only)
1340                                                         update_stages(ren1_dst,
1341                                                                       o, a, b, 1);
1342                                         }
1343                                         update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1344                                 }
1345                         }
1346                 }
1347         }
1348         path_list_clear(&a_by_dst, 0);
1349         path_list_clear(&b_by_dst, 0);
1350
1351         return clean_merge;
1352 }
1353
1354 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1355 {
1356         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1357 }
1358
1359 /* Per entry merge function */
1360 static int process_entry(const char *path, struct stage_data *entry,
1361                          const char *branch1,
1362                          const char *branch2)
1363 {
1364         /*
1365         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1366         print_index_entry("\tpath: ", entry);
1367         */
1368         int clean_merge = 1;
1369         unsigned o_mode = entry->stages[1].mode;
1370         unsigned a_mode = entry->stages[2].mode;
1371         unsigned b_mode = entry->stages[3].mode;
1372         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1373         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1374         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1375
1376         if (o_sha && (!a_sha || !b_sha)) {
1377                 /* Case A: Deleted in one */
1378                 if ((!a_sha && !b_sha) ||
1379                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1380                     (!a_sha && sha_eq(b_sha, o_sha))) {
1381                         /* Deleted in both or deleted in one and
1382                          * unchanged in the other */
1383                         if (a_sha)
1384                                 output(2, "Removed %s", path);
1385                         /* do not touch working file if it did not exist */
1386                         remove_file(1, path, !a_sha);
1387                 } else {
1388                         /* Deleted in one and changed in the other */
1389                         clean_merge = 0;
1390                         if (!a_sha) {
1391                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1392                                        "and modified in %s. Version %s of %s left in tree.",
1393                                        path, branch1,
1394                                        branch2, branch2, path);
1395                                 update_file(0, b_sha, b_mode, path);
1396                         } else {
1397                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1398                                        "and modified in %s. Version %s of %s left in tree.",
1399                                        path, branch2,
1400                                        branch1, branch1, path);
1401                                 update_file(0, a_sha, a_mode, path);
1402                         }
1403                 }
1404
1405         } else if ((!o_sha && a_sha && !b_sha) ||
1406                    (!o_sha && !a_sha && b_sha)) {
1407                 /* Case B: Added in one. */
1408                 const char *add_branch;
1409                 const char *other_branch;
1410                 unsigned mode;
1411                 const unsigned char *sha;
1412                 const char *conf;
1413
1414                 if (a_sha) {
1415                         add_branch = branch1;
1416                         other_branch = branch2;
1417                         mode = a_mode;
1418                         sha = a_sha;
1419                         conf = "file/directory";
1420                 } else {
1421                         add_branch = branch2;
1422                         other_branch = branch1;
1423                         mode = b_mode;
1424                         sha = b_sha;
1425                         conf = "directory/file";
1426                 }
1427                 if (path_list_has_path(&current_directory_set, path)) {
1428                         const char *new_path = unique_path(path, add_branch);
1429                         clean_merge = 0;
1430                         output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
1431                                "Added %s as %s",
1432                                conf, path, other_branch, path, new_path);
1433                         remove_file(0, path, 0);
1434                         update_file(0, sha, mode, new_path);
1435                 } else {
1436                         output(2, "Added %s", path);
1437                         update_file(1, sha, mode, path);
1438                 }
1439         } else if (a_sha && b_sha) {
1440                 /* Case C: Added in both (check for same permissions) and */
1441                 /* case D: Modified in both, but differently. */
1442                 const char *reason = "content";
1443                 struct merge_file_info mfi;
1444                 struct diff_filespec o, a, b;
1445
1446                 if (!o_sha) {
1447                         reason = "add/add";
1448                         o_sha = (unsigned char *)null_sha1;
1449                 }
1450                 output(2, "Auto-merged %s", path);
1451                 o.path = a.path = b.path = (char *)path;
1452                 hashcpy(o.sha1, o_sha);
1453                 o.mode = o_mode;
1454                 hashcpy(a.sha1, a_sha);
1455                 a.mode = a_mode;
1456                 hashcpy(b.sha1, b_sha);
1457                 b.mode = b_mode;
1458
1459                 mfi = merge_file(&o, &a, &b,
1460                                  branch1, branch2);
1461
1462                 clean_merge = mfi.clean;
1463                 if (mfi.clean)
1464                         update_file(1, mfi.sha, mfi.mode, path);
1465                 else if (S_ISGITLINK(mfi.mode))
1466                         output(1, "CONFLICT (submodule): Merge conflict in %s "
1467                                "- needs %s", path, sha1_to_hex(b.sha1));
1468                 else {
1469                         output(1, "CONFLICT (%s): Merge conflict in %s",
1470                                         reason, path);
1471
1472                         if (index_only)
1473                                 update_file(0, mfi.sha, mfi.mode, path);
1474                         else
1475                                 update_file_flags(mfi.sha, mfi.mode, path,
1476                                               0 /* update_cache */, 1 /* update_working_directory */);
1477                 }
1478         } else if (!o_sha && !a_sha && !b_sha) {
1479                 /*
1480                  * this entry was deleted altogether. a_mode == 0 means
1481                  * we had that path and want to actively remove it.
1482                  */
1483                 remove_file(1, path, !a_mode);
1484         } else
1485                 die("Fatal merge failure, shouldn't happen.");
1486
1487         return clean_merge;
1488 }
1489
1490 int merge_trees(struct tree *head,
1491                 struct tree *merge,
1492                 struct tree *common,
1493                 const char *branch1,
1494                 const char *branch2,
1495                 struct tree **result)
1496 {
1497         int code, clean;
1498
1499         if (subtree_merge) {
1500                 merge = shift_tree_object(head, merge);
1501                 common = shift_tree_object(head, common);
1502         }
1503
1504         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1505                 output(0, "Already uptodate!");
1506                 *result = head;
1507                 return 1;
1508         }
1509
1510         code = git_merge_trees(index_only, common, head, merge);
1511
1512         if (code != 0)
1513                 die("merging of trees %s and %s failed",
1514                     sha1_to_hex(head->object.sha1),
1515                     sha1_to_hex(merge->object.sha1));
1516
1517         if (unmerged_cache()) {
1518                 struct path_list *entries, *re_head, *re_merge;
1519                 int i;
1520                 path_list_clear(&current_file_set, 1);
1521                 path_list_clear(&current_directory_set, 1);
1522                 get_files_dirs(head);
1523                 get_files_dirs(merge);
1524
1525                 entries = get_unmerged();
1526                 re_head  = get_renames(head, common, head, merge, entries);
1527                 re_merge = get_renames(merge, common, head, merge, entries);
1528                 clean = process_renames(re_head, re_merge,
1529                                 branch1, branch2);
1530                 for (i = 0; i < entries->nr; i++) {
1531                         const char *path = entries->items[i].path;
1532                         struct stage_data *e = entries->items[i].util;
1533                         if (!e->processed
1534                                 && !process_entry(path, e, branch1, branch2))
1535                                 clean = 0;
1536                 }
1537
1538                 path_list_clear(re_merge, 0);
1539                 path_list_clear(re_head, 0);
1540                 path_list_clear(entries, 1);
1541
1542         }
1543         else
1544                 clean = 1;
1545
1546         if (index_only)
1547                 *result = write_tree_from_memory();
1548
1549         return clean;
1550 }
1551
1552 static struct commit_list *reverse_commit_list(struct commit_list *list)
1553 {
1554         struct commit_list *next = NULL, *current, *backup;
1555         for (current = list; current; current = backup) {
1556                 backup = current->next;
1557                 current->next = next;
1558                 next = current;
1559         }
1560         return next;
1561 }
1562
1563 /*
1564  * Merge the commits h1 and h2, return the resulting virtual
1565  * commit object and a flag indicating the cleanness of the merge.
1566  */
1567 int merge_recursive(struct commit *h1,
1568                     struct commit *h2,
1569                     const char *branch1,
1570                     const char *branch2,
1571                     struct commit_list *ca,
1572                     struct commit **result)
1573 {
1574         struct commit_list *iter;
1575         struct commit *merged_common_ancestors;
1576         struct tree *mrtree = mrtree;
1577         int clean;
1578
1579         if (show(4)) {
1580                 output(4, "Merging:");
1581                 output_commit_title(h1);
1582                 output_commit_title(h2);
1583         }
1584
1585         if (!ca) {
1586                 ca = get_merge_bases(h1, h2, 1);
1587                 ca = reverse_commit_list(ca);
1588         }
1589
1590         if (show(5)) {
1591                 output(5, "found %u common ancestor(s):", commit_list_count(ca));
1592                 for (iter = ca; iter; iter = iter->next)
1593                         output_commit_title(iter->item);
1594         }
1595
1596         merged_common_ancestors = pop_commit(&ca);
1597         if (merged_common_ancestors == NULL) {
1598                 /* if there is no common ancestor, make an empty tree */
1599                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1600
1601                 tree->object.parsed = 1;
1602                 tree->object.type = OBJ_TREE;
1603                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1604                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1605         }
1606
1607         for (iter = ca; iter; iter = iter->next) {
1608                 call_depth++;
1609                 /*
1610                  * When the merge fails, the result contains files
1611                  * with conflict markers. The cleanness flag is
1612                  * ignored, it was never actually used, as result of
1613                  * merge_trees has always overwritten it: the committed
1614                  * "conflicts" were already resolved.
1615                  */
1616                 discard_cache();
1617                 merge_recursive(merged_common_ancestors, iter->item,
1618                                 "Temporary merge branch 1",
1619                                 "Temporary merge branch 2",
1620                                 NULL,
1621                                 &merged_common_ancestors);
1622                 call_depth--;
1623
1624                 if (!merged_common_ancestors)
1625                         die("merge returned no commit");
1626         }
1627
1628         discard_cache();
1629         if (!call_depth) {
1630                 read_cache();
1631                 index_only = 0;
1632         } else
1633                 index_only = 1;
1634
1635         clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1636                             branch1, branch2, &mrtree);
1637
1638         if (index_only) {
1639                 *result = make_virtual_commit(mrtree, "merged tree");
1640                 commit_list_insert(h1, &(*result)->parents);
1641                 commit_list_insert(h2, &(*result)->parents->next);
1642         }
1643         flush_output();
1644         return clean;
1645 }
1646
1647 static const char *better_branch_name(const char *branch)
1648 {
1649         static char githead_env[8 + 40 + 1];
1650         char *name;
1651
1652         if (strlen(branch) != 40)
1653                 return branch;
1654         sprintf(githead_env, "GITHEAD_%s", branch);
1655         name = getenv(githead_env);
1656         return name ? name : branch;
1657 }
1658
1659 static struct commit *get_ref(const char *ref)
1660 {
1661         unsigned char sha1[20];
1662         struct object *object;
1663
1664         if (get_sha1(ref, sha1))
1665                 die("Could not resolve ref '%s'", ref);
1666         object = deref_tag(parse_object(sha1), ref, strlen(ref));
1667         if (!object)
1668                 return NULL;
1669         if (object->type == OBJ_TREE)
1670                 return make_virtual_commit((struct tree*)object,
1671                         better_branch_name(ref));
1672         if (object->type != OBJ_COMMIT)
1673                 return NULL;
1674         if (parse_commit((struct commit *)object))
1675                 die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1676         return (struct commit *)object;
1677 }
1678
1679 static int merge_config(const char *var, const char *value)
1680 {
1681         if (!strcasecmp(var, "merge.verbosity")) {
1682                 verbosity = git_config_int(var, value);
1683                 return 0;
1684         }
1685         if (!strcasecmp(var, "diff.renamelimit")) {
1686                 rename_limit = git_config_int(var, value);
1687                 return 0;
1688         }
1689         return git_default_config(var, value);
1690 }
1691
1692 int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
1693 {
1694         static const char *bases[20];
1695         static unsigned bases_count = 0;
1696         int i, clean;
1697         const char *branch1, *branch2;
1698         struct commit *result, *h1, *h2;
1699         struct commit_list *ca = NULL;
1700         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1701         int index_fd;
1702
1703         if (argv[0]) {
1704                 int namelen = strlen(argv[0]);
1705                 if (8 < namelen &&
1706                     !strcmp(argv[0] + namelen - 8, "-subtree"))
1707                         subtree_merge = 1;
1708         }
1709
1710         git_config(merge_config);
1711         if (getenv("GIT_MERGE_VERBOSITY"))
1712                 verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1713
1714         if (argc < 4)
1715                 die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1716
1717         for (i = 1; i < argc; ++i) {
1718                 if (!strcmp(argv[i], "--"))
1719                         break;
1720                 if (bases_count < sizeof(bases)/sizeof(*bases))
1721                         bases[bases_count++] = argv[i];
1722         }
1723         if (argc - i != 3) /* "--" "<head>" "<remote>" */
1724                 die("Not handling anything other than two heads merge.");
1725         if (verbosity >= 5)
1726                 buffer_output = 0;
1727
1728         branch1 = argv[++i];
1729         branch2 = argv[++i];
1730
1731         h1 = get_ref(branch1);
1732         h2 = get_ref(branch2);
1733
1734         branch1 = better_branch_name(branch1);
1735         branch2 = better_branch_name(branch2);
1736
1737         if (show(3))
1738                 printf("Merging %s with %s\n", branch1, branch2);
1739
1740         index_fd = hold_locked_index(lock, 1);
1741
1742         for (i = 0; i < bases_count; i++) {
1743                 struct commit *ancestor = get_ref(bases[i]);
1744                 ca = commit_list_insert(ancestor, &ca);
1745         }
1746         clean = merge_recursive(h1, h2, branch1, branch2, ca, &result);
1747
1748         if (active_cache_changed &&
1749             (write_cache(index_fd, active_cache, active_nr) ||
1750              commit_locked_index(lock)))
1751                         die ("unable to write %s", get_index_file());
1752
1753         return clean ? 0: 1;
1754 }