Merge branch 'nm/submodule-update-force'
[git] / builtin / merge.c
1 /*
2  * Builtin "git merge"
3  *
4  * Copyright (c) 2008 Miklos Vajna <vmiklos@frugalware.org>
5  *
6  * Based on git-merge.sh by Junio C Hamano.
7  */
8
9 #include "cache.h"
10 #include "parse-options.h"
11 #include "builtin.h"
12 #include "run-command.h"
13 #include "diff.h"
14 #include "refs.h"
15 #include "commit.h"
16 #include "diffcore.h"
17 #include "revision.h"
18 #include "unpack-trees.h"
19 #include "cache-tree.h"
20 #include "dir.h"
21 #include "utf8.h"
22 #include "log-tree.h"
23 #include "color.h"
24 #include "rerere.h"
25 #include "help.h"
26 #include "merge-recursive.h"
27 #include "resolve-undo.h"
28 #include "remote.h"
29
30 #define DEFAULT_TWOHEAD (1<<0)
31 #define DEFAULT_OCTOPUS (1<<1)
32 #define NO_FAST_FORWARD (1<<2)
33 #define NO_TRIVIAL      (1<<3)
34
35 struct strategy {
36         const char *name;
37         unsigned attr;
38 };
39
40 static const char * const builtin_merge_usage[] = {
41         "git merge [options] [<commit>...]",
42         "git merge [options] <msg> HEAD <commit>",
43         "git merge --abort",
44         NULL
45 };
46
47 static int show_diffstat = 1, shortlog_len, squash;
48 static int option_commit = 1, allow_fast_forward = 1;
49 static int fast_forward_only;
50 static int allow_trivial = 1, have_message;
51 static struct strbuf merge_msg;
52 static struct commit_list *remoteheads;
53 static unsigned char head[20], stash[20];
54 static struct strategy **use_strategies;
55 static size_t use_strategies_nr, use_strategies_alloc;
56 static const char **xopts;
57 static size_t xopts_nr, xopts_alloc;
58 static const char *branch;
59 static int option_renormalize;
60 static int verbosity;
61 static int allow_rerere_auto;
62 static int abort_current_merge;
63 static int show_progress = -1;
64 static int default_to_upstream;
65
66 static struct strategy all_strategy[] = {
67         { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
68         { "octopus",    DEFAULT_OCTOPUS },
69         { "resolve",    0 },
70         { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
71         { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
72 };
73
74 static const char *pull_twohead, *pull_octopus;
75
76 static int option_parse_message(const struct option *opt,
77                                 const char *arg, int unset)
78 {
79         struct strbuf *buf = opt->value;
80
81         if (unset)
82                 strbuf_setlen(buf, 0);
83         else if (arg) {
84                 strbuf_addf(buf, "%s%s", buf->len ? "\n\n" : "", arg);
85                 have_message = 1;
86         } else
87                 return error(_("switch `m' requires a value"));
88         return 0;
89 }
90
91 static struct strategy *get_strategy(const char *name)
92 {
93         int i;
94         struct strategy *ret;
95         static struct cmdnames main_cmds, other_cmds;
96         static int loaded;
97
98         if (!name)
99                 return NULL;
100
101         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
102                 if (!strcmp(name, all_strategy[i].name))
103                         return &all_strategy[i];
104
105         if (!loaded) {
106                 struct cmdnames not_strategies;
107                 loaded = 1;
108
109                 memset(&not_strategies, 0, sizeof(struct cmdnames));
110                 load_command_list("git-merge-", &main_cmds, &other_cmds);
111                 for (i = 0; i < main_cmds.cnt; i++) {
112                         int j, found = 0;
113                         struct cmdname *ent = main_cmds.names[i];
114                         for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
115                                 if (!strncmp(ent->name, all_strategy[j].name, ent->len)
116                                                 && !all_strategy[j].name[ent->len])
117                                         found = 1;
118                         if (!found)
119                                 add_cmdname(&not_strategies, ent->name, ent->len);
120                 }
121                 exclude_cmds(&main_cmds, &not_strategies);
122         }
123         if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
124                 fprintf(stderr, _("Could not find merge strategy '%s'.\n"), name);
125                 fprintf(stderr, _("Available strategies are:"));
126                 for (i = 0; i < main_cmds.cnt; i++)
127                         fprintf(stderr, " %s", main_cmds.names[i]->name);
128                 fprintf(stderr, ".\n");
129                 if (other_cmds.cnt) {
130                         fprintf(stderr, _("Available custom strategies are:"));
131                         for (i = 0; i < other_cmds.cnt; i++)
132                                 fprintf(stderr, " %s", other_cmds.names[i]->name);
133                         fprintf(stderr, ".\n");
134                 }
135                 exit(1);
136         }
137
138         ret = xcalloc(1, sizeof(struct strategy));
139         ret->name = xstrdup(name);
140         ret->attr = NO_TRIVIAL;
141         return ret;
142 }
143
144 static void append_strategy(struct strategy *s)
145 {
146         ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
147         use_strategies[use_strategies_nr++] = s;
148 }
149
150 static int option_parse_strategy(const struct option *opt,
151                                  const char *name, int unset)
152 {
153         if (unset)
154                 return 0;
155
156         append_strategy(get_strategy(name));
157         return 0;
158 }
159
160 static int option_parse_x(const struct option *opt,
161                           const char *arg, int unset)
162 {
163         if (unset)
164                 return 0;
165
166         ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
167         xopts[xopts_nr++] = xstrdup(arg);
168         return 0;
169 }
170
171 static int option_parse_n(const struct option *opt,
172                           const char *arg, int unset)
173 {
174         show_diffstat = unset;
175         return 0;
176 }
177
178 static struct option builtin_merge_options[] = {
179         { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
180                 "do not show a diffstat at the end of the merge",
181                 PARSE_OPT_NOARG, option_parse_n },
182         OPT_BOOLEAN(0, "stat", &show_diffstat,
183                 "show a diffstat at the end of the merge"),
184         OPT_BOOLEAN(0, "summary", &show_diffstat, "(synonym to --stat)"),
185         { OPTION_INTEGER, 0, "log", &shortlog_len, "n",
186           "add (at most <n>) entries from shortlog to merge commit message",
187           PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
188         OPT_BOOLEAN(0, "squash", &squash,
189                 "create a single commit instead of doing a merge"),
190         OPT_BOOLEAN(0, "commit", &option_commit,
191                 "perform a commit if the merge succeeds (default)"),
192         OPT_BOOLEAN(0, "ff", &allow_fast_forward,
193                 "allow fast-forward (default)"),
194         OPT_BOOLEAN(0, "ff-only", &fast_forward_only,
195                 "abort if fast-forward is not possible"),
196         OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
197         OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
198                 "merge strategy to use", option_parse_strategy),
199         OPT_CALLBACK('X', "strategy-option", &xopts, "option=value",
200                 "option for selected merge strategy", option_parse_x),
201         OPT_CALLBACK('m', "message", &merge_msg, "message",
202                 "merge commit message (for a non-fast-forward merge)",
203                 option_parse_message),
204         OPT__VERBOSITY(&verbosity),
205         OPT_BOOLEAN(0, "abort", &abort_current_merge,
206                 "abort the current in-progress merge"),
207         OPT_SET_INT(0, "progress", &show_progress, "force progress reporting", 1),
208         OPT_END()
209 };
210
211 /* Cleans up metadata that is uninteresting after a succeeded merge. */
212 static void drop_save(void)
213 {
214         unlink(git_path("MERGE_HEAD"));
215         unlink(git_path("MERGE_MSG"));
216         unlink(git_path("MERGE_MODE"));
217 }
218
219 static void save_state(void)
220 {
221         int len;
222         struct child_process cp;
223         struct strbuf buffer = STRBUF_INIT;
224         const char *argv[] = {"stash", "create", NULL};
225
226         memset(&cp, 0, sizeof(cp));
227         cp.argv = argv;
228         cp.out = -1;
229         cp.git_cmd = 1;
230
231         if (start_command(&cp))
232                 die(_("could not run stash."));
233         len = strbuf_read(&buffer, cp.out, 1024);
234         close(cp.out);
235
236         if (finish_command(&cp) || len < 0)
237                 die(_("stash failed"));
238         else if (!len)
239                 return;
240         strbuf_setlen(&buffer, buffer.len-1);
241         if (get_sha1(buffer.buf, stash))
242                 die(_("not a valid object: %s"), buffer.buf);
243 }
244
245 static void read_empty(unsigned const char *sha1, int verbose)
246 {
247         int i = 0;
248         const char *args[7];
249
250         args[i++] = "read-tree";
251         if (verbose)
252                 args[i++] = "-v";
253         args[i++] = "-m";
254         args[i++] = "-u";
255         args[i++] = EMPTY_TREE_SHA1_HEX;
256         args[i++] = sha1_to_hex(sha1);
257         args[i] = NULL;
258
259         if (run_command_v_opt(args, RUN_GIT_CMD))
260                 die(_("read-tree failed"));
261 }
262
263 static void reset_hard(unsigned const char *sha1, int verbose)
264 {
265         int i = 0;
266         const char *args[6];
267
268         args[i++] = "read-tree";
269         if (verbose)
270                 args[i++] = "-v";
271         args[i++] = "--reset";
272         args[i++] = "-u";
273         args[i++] = sha1_to_hex(sha1);
274         args[i] = NULL;
275
276         if (run_command_v_opt(args, RUN_GIT_CMD))
277                 die(_("read-tree failed"));
278 }
279
280 static void restore_state(void)
281 {
282         struct strbuf sb = STRBUF_INIT;
283         const char *args[] = { "stash", "apply", NULL, NULL };
284
285         if (is_null_sha1(stash))
286                 return;
287
288         reset_hard(head, 1);
289
290         args[2] = sha1_to_hex(stash);
291
292         /*
293          * It is OK to ignore error here, for example when there was
294          * nothing to restore.
295          */
296         run_command_v_opt(args, RUN_GIT_CMD);
297
298         strbuf_release(&sb);
299         refresh_cache(REFRESH_QUIET);
300 }
301
302 /* This is called when no merge was necessary. */
303 static void finish_up_to_date(const char *msg)
304 {
305         if (verbosity >= 0)
306                 printf("%s%s\n", squash ? _(" (nothing to squash)") : "", msg);
307         drop_save();
308 }
309
310 static void squash_message(void)
311 {
312         struct rev_info rev;
313         struct commit *commit;
314         struct strbuf out = STRBUF_INIT;
315         struct commit_list *j;
316         int fd;
317         struct pretty_print_context ctx = {0};
318
319         printf(_("Squash commit -- not updating HEAD\n"));
320         fd = open(git_path("SQUASH_MSG"), O_WRONLY | O_CREAT, 0666);
321         if (fd < 0)
322                 die_errno(_("Could not write to '%s'"), git_path("SQUASH_MSG"));
323
324         init_revisions(&rev, NULL);
325         rev.ignore_merges = 1;
326         rev.commit_format = CMIT_FMT_MEDIUM;
327
328         commit = lookup_commit(head);
329         commit->object.flags |= UNINTERESTING;
330         add_pending_object(&rev, &commit->object, NULL);
331
332         for (j = remoteheads; j; j = j->next)
333                 add_pending_object(&rev, &j->item->object, NULL);
334
335         setup_revisions(0, NULL, &rev, NULL);
336         if (prepare_revision_walk(&rev))
337                 die(_("revision walk setup failed"));
338
339         ctx.abbrev = rev.abbrev;
340         ctx.date_mode = rev.date_mode;
341
342         strbuf_addstr(&out, "Squashed commit of the following:\n");
343         while ((commit = get_revision(&rev)) != NULL) {
344                 strbuf_addch(&out, '\n');
345                 strbuf_addf(&out, "commit %s\n",
346                         sha1_to_hex(commit->object.sha1));
347                 pretty_print_commit(rev.commit_format, commit, &out, &ctx);
348         }
349         if (write(fd, out.buf, out.len) < 0)
350                 die_errno(_("Writing SQUASH_MSG"));
351         if (close(fd))
352                 die_errno(_("Finishing SQUASH_MSG"));
353         strbuf_release(&out);
354 }
355
356 static void finish(const unsigned char *new_head, const char *msg)
357 {
358         struct strbuf reflog_message = STRBUF_INIT;
359
360         if (!msg)
361                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
362         else {
363                 if (verbosity >= 0)
364                         printf("%s\n", msg);
365                 strbuf_addf(&reflog_message, "%s: %s",
366                         getenv("GIT_REFLOG_ACTION"), msg);
367         }
368         if (squash) {
369                 squash_message();
370         } else {
371                 if (verbosity >= 0 && !merge_msg.len)
372                         printf(_("No merge message -- not updating HEAD\n"));
373                 else {
374                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
375                         update_ref(reflog_message.buf, "HEAD",
376                                 new_head, head, 0,
377                                 DIE_ON_ERR);
378                         /*
379                          * We ignore errors in 'gc --auto', since the
380                          * user should see them.
381                          */
382                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
383                 }
384         }
385         if (new_head && show_diffstat) {
386                 struct diff_options opts;
387                 diff_setup(&opts);
388                 opts.output_format |=
389                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
390                 opts.detect_rename = DIFF_DETECT_RENAME;
391                 if (diff_use_color_default > 0)
392                         DIFF_OPT_SET(&opts, COLOR_DIFF);
393                 if (diff_setup_done(&opts) < 0)
394                         die(_("diff_setup_done failed"));
395                 diff_tree_sha1(head, new_head, "", &opts);
396                 diffcore_std(&opts);
397                 diff_flush(&opts);
398         }
399
400         /* Run a post-merge hook */
401         run_hook(NULL, "post-merge", squash ? "1" : "0", NULL);
402
403         strbuf_release(&reflog_message);
404 }
405
406 /* Get the name for the merge commit's message. */
407 static void merge_name(const char *remote, struct strbuf *msg)
408 {
409         struct object *remote_head;
410         unsigned char branch_head[20], buf_sha[20];
411         struct strbuf buf = STRBUF_INIT;
412         struct strbuf bname = STRBUF_INIT;
413         const char *ptr;
414         char *found_ref;
415         int len, early;
416
417         strbuf_branchname(&bname, remote);
418         remote = bname.buf;
419
420         memset(branch_head, 0, sizeof(branch_head));
421         remote_head = peel_to_type(remote, 0, NULL, OBJ_COMMIT);
422         if (!remote_head)
423                 die(_("'%s' does not point to a commit"), remote);
424
425         if (dwim_ref(remote, strlen(remote), branch_head, &found_ref) > 0) {
426                 if (!prefixcmp(found_ref, "refs/heads/")) {
427                         strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
428                                     sha1_to_hex(branch_head), remote);
429                         goto cleanup;
430                 }
431                 if (!prefixcmp(found_ref, "refs/remotes/")) {
432                         strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
433                                     sha1_to_hex(branch_head), remote);
434                         goto cleanup;
435                 }
436         }
437
438         /* See if remote matches <name>^^^.. or <name>~<number> */
439         for (len = 0, ptr = remote + strlen(remote);
440              remote < ptr && ptr[-1] == '^';
441              ptr--)
442                 len++;
443         if (len)
444                 early = 1;
445         else {
446                 early = 0;
447                 ptr = strrchr(remote, '~');
448                 if (ptr) {
449                         int seen_nonzero = 0;
450
451                         len++; /* count ~ */
452                         while (*++ptr && isdigit(*ptr)) {
453                                 seen_nonzero |= (*ptr != '0');
454                                 len++;
455                         }
456                         if (*ptr)
457                                 len = 0; /* not ...~<number> */
458                         else if (seen_nonzero)
459                                 early = 1;
460                         else if (len == 1)
461                                 early = 1; /* "name~" is "name~1"! */
462                 }
463         }
464         if (len) {
465                 struct strbuf truname = STRBUF_INIT;
466                 strbuf_addstr(&truname, "refs/heads/");
467                 strbuf_addstr(&truname, remote);
468                 strbuf_setlen(&truname, truname.len - len);
469                 if (resolve_ref(truname.buf, buf_sha, 1, NULL)) {
470                         strbuf_addf(msg,
471                                     "%s\t\tbranch '%s'%s of .\n",
472                                     sha1_to_hex(remote_head->sha1),
473                                     truname.buf + 11,
474                                     (early ? " (early part)" : ""));
475                         strbuf_release(&truname);
476                         goto cleanup;
477                 }
478         }
479
480         if (!strcmp(remote, "FETCH_HEAD") &&
481                         !access(git_path("FETCH_HEAD"), R_OK)) {
482                 FILE *fp;
483                 struct strbuf line = STRBUF_INIT;
484                 char *ptr;
485
486                 fp = fopen(git_path("FETCH_HEAD"), "r");
487                 if (!fp)
488                         die_errno(_("could not open '%s' for reading"),
489                                   git_path("FETCH_HEAD"));
490                 strbuf_getline(&line, fp, '\n');
491                 fclose(fp);
492                 ptr = strstr(line.buf, "\tnot-for-merge\t");
493                 if (ptr)
494                         strbuf_remove(&line, ptr-line.buf+1, 13);
495                 strbuf_addbuf(msg, &line);
496                 strbuf_release(&line);
497                 goto cleanup;
498         }
499         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
500                 sha1_to_hex(remote_head->sha1), remote);
501 cleanup:
502         strbuf_release(&buf);
503         strbuf_release(&bname);
504 }
505
506 static int git_merge_config(const char *k, const char *v, void *cb)
507 {
508         if (branch && !prefixcmp(k, "branch.") &&
509                 !prefixcmp(k + 7, branch) &&
510                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
511                 const char **argv;
512                 int argc;
513                 char *buf;
514
515                 buf = xstrdup(v);
516                 argc = split_cmdline(buf, &argv);
517                 if (argc < 0)
518                         die(_("Bad branch.%s.mergeoptions string: %s"), branch,
519                             split_cmdline_strerror(argc));
520                 argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
521                 memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
522                 argc++;
523                 parse_options(argc, argv, NULL, builtin_merge_options,
524                               builtin_merge_usage, 0);
525                 free(buf);
526         }
527
528         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
529                 show_diffstat = git_config_bool(k, v);
530         else if (!strcmp(k, "pull.twohead"))
531                 return git_config_string(&pull_twohead, k, v);
532         else if (!strcmp(k, "pull.octopus"))
533                 return git_config_string(&pull_octopus, k, v);
534         else if (!strcmp(k, "merge.renormalize"))
535                 option_renormalize = git_config_bool(k, v);
536         else if (!strcmp(k, "merge.log") || !strcmp(k, "merge.summary")) {
537                 int is_bool;
538                 shortlog_len = git_config_bool_or_int(k, v, &is_bool);
539                 if (!is_bool && shortlog_len < 0)
540                         return error(_("%s: negative length %s"), k, v);
541                 if (is_bool && shortlog_len)
542                         shortlog_len = DEFAULT_MERGE_LOG_LEN;
543                 return 0;
544         } else if (!strcmp(k, "merge.defaulttoupstream")) {
545                 default_to_upstream = git_config_bool(k, v);
546                 return 0;
547         }
548         return git_diff_ui_config(k, v, cb);
549 }
550
551 static int read_tree_trivial(unsigned char *common, unsigned char *head,
552                              unsigned char *one)
553 {
554         int i, nr_trees = 0;
555         struct tree *trees[MAX_UNPACK_TREES];
556         struct tree_desc t[MAX_UNPACK_TREES];
557         struct unpack_trees_options opts;
558
559         memset(&opts, 0, sizeof(opts));
560         opts.head_idx = 2;
561         opts.src_index = &the_index;
562         opts.dst_index = &the_index;
563         opts.update = 1;
564         opts.verbose_update = 1;
565         opts.trivial_merges_only = 1;
566         opts.merge = 1;
567         trees[nr_trees] = parse_tree_indirect(common);
568         if (!trees[nr_trees++])
569                 return -1;
570         trees[nr_trees] = parse_tree_indirect(head);
571         if (!trees[nr_trees++])
572                 return -1;
573         trees[nr_trees] = parse_tree_indirect(one);
574         if (!trees[nr_trees++])
575                 return -1;
576         opts.fn = threeway_merge;
577         cache_tree_free(&active_cache_tree);
578         for (i = 0; i < nr_trees; i++) {
579                 parse_tree(trees[i]);
580                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
581         }
582         if (unpack_trees(nr_trees, t, &opts))
583                 return -1;
584         return 0;
585 }
586
587 static void write_tree_trivial(unsigned char *sha1)
588 {
589         if (write_cache_as_tree(sha1, 0, NULL))
590                 die(_("git write-tree failed to write a tree"));
591 }
592
593 int try_merge_command(const char *strategy, size_t xopts_nr,
594                       const char **xopts, struct commit_list *common,
595                       const char *head_arg, struct commit_list *remotes)
596 {
597         const char **args;
598         int i = 0, x = 0, ret;
599         struct commit_list *j;
600         struct strbuf buf = STRBUF_INIT;
601
602         args = xmalloc((4 + xopts_nr + commit_list_count(common) +
603                         commit_list_count(remotes)) * sizeof(char *));
604         strbuf_addf(&buf, "merge-%s", strategy);
605         args[i++] = buf.buf;
606         for (x = 0; x < xopts_nr; x++) {
607                 char *s = xmalloc(strlen(xopts[x])+2+1);
608                 strcpy(s, "--");
609                 strcpy(s+2, xopts[x]);
610                 args[i++] = s;
611         }
612         for (j = common; j; j = j->next)
613                 args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
614         args[i++] = "--";
615         args[i++] = head_arg;
616         for (j = remotes; j; j = j->next)
617                 args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
618         args[i] = NULL;
619         ret = run_command_v_opt(args, RUN_GIT_CMD);
620         strbuf_release(&buf);
621         i = 1;
622         for (x = 0; x < xopts_nr; x++)
623                 free((void *)args[i++]);
624         for (j = common; j; j = j->next)
625                 free((void *)args[i++]);
626         i += 2;
627         for (j = remotes; j; j = j->next)
628                 free((void *)args[i++]);
629         free(args);
630         discard_cache();
631         if (read_cache() < 0)
632                 die(_("failed to read the cache"));
633         resolve_undo_clear();
634
635         return ret;
636 }
637
638 static int try_merge_strategy(const char *strategy, struct commit_list *common,
639                               const char *head_arg)
640 {
641         int index_fd;
642         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
643
644         index_fd = hold_locked_index(lock, 1);
645         refresh_cache(REFRESH_QUIET);
646         if (active_cache_changed &&
647                         (write_cache(index_fd, active_cache, active_nr) ||
648                          commit_locked_index(lock)))
649                 return error(_("Unable to write index."));
650         rollback_lock_file(lock);
651
652         if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
653                 int clean, x;
654                 struct commit *result;
655                 struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
656                 int index_fd;
657                 struct commit_list *reversed = NULL;
658                 struct merge_options o;
659                 struct commit_list *j;
660
661                 if (remoteheads->next) {
662                         error(_("Not handling anything other than two heads merge."));
663                         return 2;
664                 }
665
666                 init_merge_options(&o);
667                 if (!strcmp(strategy, "subtree"))
668                         o.subtree_shift = "";
669
670                 o.renormalize = option_renormalize;
671                 o.show_rename_progress =
672                         show_progress == -1 ? isatty(2) : show_progress;
673
674                 for (x = 0; x < xopts_nr; x++)
675                         if (parse_merge_opt(&o, xopts[x]))
676                                 die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
677
678                 o.branch1 = head_arg;
679                 o.branch2 = remoteheads->item->util;
680
681                 for (j = common; j; j = j->next)
682                         commit_list_insert(j->item, &reversed);
683
684                 index_fd = hold_locked_index(lock, 1);
685                 clean = merge_recursive(&o, lookup_commit(head),
686                                 remoteheads->item, reversed, &result);
687                 if (active_cache_changed &&
688                                 (write_cache(index_fd, active_cache, active_nr) ||
689                                  commit_locked_index(lock)))
690                         die (_("unable to write %s"), get_index_file());
691                 rollback_lock_file(lock);
692                 return clean ? 0 : 1;
693         } else {
694                 return try_merge_command(strategy, xopts_nr, xopts,
695                                                 common, head_arg, remoteheads);
696         }
697 }
698
699 static void count_diff_files(struct diff_queue_struct *q,
700                              struct diff_options *opt, void *data)
701 {
702         int *count = data;
703
704         (*count) += q->nr;
705 }
706
707 static int count_unmerged_entries(void)
708 {
709         int i, ret = 0;
710
711         for (i = 0; i < active_nr; i++)
712                 if (ce_stage(active_cache[i]))
713                         ret++;
714
715         return ret;
716 }
717
718 int checkout_fast_forward(const unsigned char *head, const unsigned char *remote)
719 {
720         struct tree *trees[MAX_UNPACK_TREES];
721         struct unpack_trees_options opts;
722         struct tree_desc t[MAX_UNPACK_TREES];
723         int i, fd, nr_trees = 0;
724         struct dir_struct dir;
725         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
726
727         refresh_cache(REFRESH_QUIET);
728
729         fd = hold_locked_index(lock_file, 1);
730
731         memset(&trees, 0, sizeof(trees));
732         memset(&opts, 0, sizeof(opts));
733         memset(&t, 0, sizeof(t));
734         memset(&dir, 0, sizeof(dir));
735         dir.flags |= DIR_SHOW_IGNORED;
736         dir.exclude_per_dir = ".gitignore";
737         opts.dir = &dir;
738
739         opts.head_idx = 1;
740         opts.src_index = &the_index;
741         opts.dst_index = &the_index;
742         opts.update = 1;
743         opts.verbose_update = 1;
744         opts.merge = 1;
745         opts.fn = twoway_merge;
746         setup_unpack_trees_porcelain(&opts, "merge");
747
748         trees[nr_trees] = parse_tree_indirect(head);
749         if (!trees[nr_trees++])
750                 return -1;
751         trees[nr_trees] = parse_tree_indirect(remote);
752         if (!trees[nr_trees++])
753                 return -1;
754         for (i = 0; i < nr_trees; i++) {
755                 parse_tree(trees[i]);
756                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
757         }
758         if (unpack_trees(nr_trees, t, &opts))
759                 return -1;
760         if (write_cache(fd, active_cache, active_nr) ||
761                 commit_locked_index(lock_file))
762                 die(_("unable to write new index file"));
763         return 0;
764 }
765
766 static void split_merge_strategies(const char *string, struct strategy **list,
767                                    int *nr, int *alloc)
768 {
769         char *p, *q, *buf;
770
771         if (!string)
772                 return;
773
774         buf = xstrdup(string);
775         q = buf;
776         for (;;) {
777                 p = strchr(q, ' ');
778                 if (!p) {
779                         ALLOC_GROW(*list, *nr + 1, *alloc);
780                         (*list)[(*nr)++].name = xstrdup(q);
781                         free(buf);
782                         return;
783                 } else {
784                         *p = '\0';
785                         ALLOC_GROW(*list, *nr + 1, *alloc);
786                         (*list)[(*nr)++].name = xstrdup(q);
787                         q = ++p;
788                 }
789         }
790 }
791
792 static void add_strategies(const char *string, unsigned attr)
793 {
794         struct strategy *list = NULL;
795         int list_alloc = 0, list_nr = 0, i;
796
797         memset(&list, 0, sizeof(list));
798         split_merge_strategies(string, &list, &list_nr, &list_alloc);
799         if (list) {
800                 for (i = 0; i < list_nr; i++)
801                         append_strategy(get_strategy(list[i].name));
802                 return;
803         }
804         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
805                 if (all_strategy[i].attr & attr)
806                         append_strategy(&all_strategy[i]);
807
808 }
809
810 static void write_merge_msg(void)
811 {
812         int fd = open(git_path("MERGE_MSG"), O_WRONLY | O_CREAT, 0666);
813         if (fd < 0)
814                 die_errno(_("Could not open '%s' for writing"),
815                           git_path("MERGE_MSG"));
816         if (write_in_full(fd, merge_msg.buf, merge_msg.len) != merge_msg.len)
817                 die_errno(_("Could not write to '%s'"), git_path("MERGE_MSG"));
818         close(fd);
819 }
820
821 static void read_merge_msg(void)
822 {
823         strbuf_reset(&merge_msg);
824         if (strbuf_read_file(&merge_msg, git_path("MERGE_MSG"), 0) < 0)
825                 die_errno("Could not read from '%s'", git_path("MERGE_MSG"));
826 }
827
828 static void run_prepare_commit_msg(void)
829 {
830         write_merge_msg();
831         run_hook(get_index_file(), "prepare-commit-msg",
832                  git_path("MERGE_MSG"), "merge", NULL, NULL);
833         read_merge_msg();
834 }
835
836 static int merge_trivial(void)
837 {
838         unsigned char result_tree[20], result_commit[20];
839         struct commit_list *parent = xmalloc(sizeof(*parent));
840
841         write_tree_trivial(result_tree);
842         printf(_("Wonderful.\n"));
843         parent->item = lookup_commit(head);
844         parent->next = xmalloc(sizeof(*parent->next));
845         parent->next->item = remoteheads->item;
846         parent->next->next = NULL;
847         run_prepare_commit_msg();
848         commit_tree(merge_msg.buf, result_tree, parent, result_commit, NULL);
849         finish(result_commit, "In-index merge");
850         drop_save();
851         return 0;
852 }
853
854 static int finish_automerge(struct commit_list *common,
855                             unsigned char *result_tree,
856                             const char *wt_strategy)
857 {
858         struct commit_list *parents = NULL, *j;
859         struct strbuf buf = STRBUF_INIT;
860         unsigned char result_commit[20];
861
862         free_commit_list(common);
863         if (allow_fast_forward) {
864                 parents = remoteheads;
865                 commit_list_insert(lookup_commit(head), &parents);
866                 parents = reduce_heads(parents);
867         } else {
868                 struct commit_list **pptr = &parents;
869
870                 pptr = &commit_list_insert(lookup_commit(head),
871                                 pptr)->next;
872                 for (j = remoteheads; j; j = j->next)
873                         pptr = &commit_list_insert(j->item, pptr)->next;
874         }
875         free_commit_list(remoteheads);
876         strbuf_addch(&merge_msg, '\n');
877         run_prepare_commit_msg();
878         commit_tree(merge_msg.buf, result_tree, parents, result_commit, NULL);
879         strbuf_addf(&buf, "Merge made by %s.", wt_strategy);
880         finish(result_commit, buf.buf);
881         strbuf_release(&buf);
882         drop_save();
883         return 0;
884 }
885
886 static int suggest_conflicts(int renormalizing)
887 {
888         FILE *fp;
889         int pos;
890
891         fp = fopen(git_path("MERGE_MSG"), "a");
892         if (!fp)
893                 die_errno(_("Could not open '%s' for writing"),
894                           git_path("MERGE_MSG"));
895         fprintf(fp, "\nConflicts:\n");
896         for (pos = 0; pos < active_nr; pos++) {
897                 struct cache_entry *ce = active_cache[pos];
898
899                 if (ce_stage(ce)) {
900                         fprintf(fp, "\t%s\n", ce->name);
901                         while (pos + 1 < active_nr &&
902                                         !strcmp(ce->name,
903                                                 active_cache[pos + 1]->name))
904                                 pos++;
905                 }
906         }
907         fclose(fp);
908         rerere(allow_rerere_auto);
909         printf(_("Automatic merge failed; "
910                         "fix conflicts and then commit the result.\n"));
911         return 1;
912 }
913
914 static struct commit *is_old_style_invocation(int argc, const char **argv)
915 {
916         struct commit *second_token = NULL;
917         if (argc > 2) {
918                 unsigned char second_sha1[20];
919
920                 if (get_sha1(argv[1], second_sha1))
921                         return NULL;
922                 second_token = lookup_commit_reference_gently(second_sha1, 0);
923                 if (!second_token)
924                         die(_("'%s' is not a commit"), argv[1]);
925                 if (hashcmp(second_token->object.sha1, head))
926                         return NULL;
927         }
928         return second_token;
929 }
930
931 static int evaluate_result(void)
932 {
933         int cnt = 0;
934         struct rev_info rev;
935
936         /* Check how many files differ. */
937         init_revisions(&rev, "");
938         setup_revisions(0, NULL, &rev, NULL);
939         rev.diffopt.output_format |=
940                 DIFF_FORMAT_CALLBACK;
941         rev.diffopt.format_callback = count_diff_files;
942         rev.diffopt.format_callback_data = &cnt;
943         run_diff_files(&rev, 0);
944
945         /*
946          * Check how many unmerged entries are
947          * there.
948          */
949         cnt += count_unmerged_entries();
950
951         return cnt;
952 }
953
954 /*
955  * Pretend as if the user told us to merge with the tracking
956  * branch we have for the upstream of the current branch
957  */
958 static int setup_with_upstream(const char ***argv)
959 {
960         struct branch *branch = branch_get(NULL);
961         int i;
962         const char **args;
963
964         if (!branch)
965                 die("No current branch.");
966         if (!branch->remote)
967                 die("No remote for the current branch.");
968         if (!branch->merge_nr)
969                 die("No default upstream defined for the current branch.");
970
971         args = xcalloc(branch->merge_nr + 1, sizeof(char *));
972         for (i = 0; i < branch->merge_nr; i++) {
973                 if (!branch->merge[i]->dst)
974                         die("No remote tracking branch for %s from %s",
975                             branch->merge[i]->src, branch->remote_name);
976                 args[i] = branch->merge[i]->dst;
977         }
978         args[i] = NULL;
979         *argv = args;
980         return i;
981 }
982
983 int cmd_merge(int argc, const char **argv, const char *prefix)
984 {
985         unsigned char result_tree[20];
986         struct strbuf buf = STRBUF_INIT;
987         const char *head_arg;
988         int flag, head_invalid = 0, i;
989         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
990         struct commit_list *common = NULL;
991         const char *best_strategy = NULL, *wt_strategy = NULL;
992         struct commit_list **remotes = &remoteheads;
993
994         if (argc == 2 && !strcmp(argv[1], "-h"))
995                 usage_with_options(builtin_merge_usage, builtin_merge_options);
996
997         /*
998          * Check if we are _not_ on a detached HEAD, i.e. if there is a
999          * current branch.
1000          */
1001         branch = resolve_ref("HEAD", head, 0, &flag);
1002         if (branch && !prefixcmp(branch, "refs/heads/"))
1003                 branch += 11;
1004         if (is_null_sha1(head))
1005                 head_invalid = 1;
1006
1007         git_config(git_merge_config, NULL);
1008
1009         /* for color.ui */
1010         if (diff_use_color_default == -1)
1011                 diff_use_color_default = git_use_color_default;
1012
1013         argc = parse_options(argc, argv, prefix, builtin_merge_options,
1014                         builtin_merge_usage, 0);
1015
1016         if (verbosity < 0 && show_progress == -1)
1017                 show_progress = 0;
1018
1019         if (abort_current_merge) {
1020                 int nargc = 2;
1021                 const char *nargv[] = {"reset", "--merge", NULL};
1022
1023                 if (!file_exists(git_path("MERGE_HEAD")))
1024                         die(_("There is no merge to abort (MERGE_HEAD missing)."));
1025
1026                 /* Invoke 'git reset --merge' */
1027                 return cmd_reset(nargc, nargv, prefix);
1028         }
1029
1030         if (read_cache_unmerged())
1031                 die_resolve_conflict("merge");
1032
1033         if (file_exists(git_path("MERGE_HEAD"))) {
1034                 /*
1035                  * There is no unmerged entry, don't advise 'git
1036                  * add/rm <file>', just 'git commit'.
1037                  */
1038                 if (advice_resolve_conflict)
1039                         die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1040                                   "Please, commit your changes before you can merge."));
1041                 else
1042                         die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1043         }
1044         if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
1045                 if (advice_resolve_conflict)
1046                         die("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1047                             "Please, commit your changes before you can merge.");
1048                 else
1049                         die("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).");
1050         }
1051         resolve_undo_clear();
1052
1053         if (verbosity < 0)
1054                 show_diffstat = 0;
1055
1056         if (squash) {
1057                 if (!allow_fast_forward)
1058                         die(_("You cannot combine --squash with --no-ff."));
1059                 option_commit = 0;
1060         }
1061
1062         if (!allow_fast_forward && fast_forward_only)
1063                 die(_("You cannot combine --no-ff with --ff-only."));
1064
1065         if (!abort_current_merge) {
1066                 if (!argc && default_to_upstream)
1067                         argc = setup_with_upstream(&argv);
1068                 else if (argc == 1 && !strcmp(argv[0], "-"))
1069                         argv[0] = "@{-1}";
1070         }
1071         if (!argc)
1072                 usage_with_options(builtin_merge_usage,
1073                         builtin_merge_options);
1074
1075         /*
1076          * This could be traditional "merge <msg> HEAD <commit>..."  and
1077          * the way we can tell it is to see if the second token is HEAD,
1078          * but some people might have misused the interface and used a
1079          * committish that is the same as HEAD there instead.
1080          * Traditional format never would have "-m" so it is an
1081          * additional safety measure to check for it.
1082          */
1083
1084         if (!have_message && is_old_style_invocation(argc, argv)) {
1085                 strbuf_addstr(&merge_msg, argv[0]);
1086                 head_arg = argv[1];
1087                 argv += 2;
1088                 argc -= 2;
1089         } else if (head_invalid) {
1090                 struct object *remote_head;
1091                 /*
1092                  * If the merged head is a valid one there is no reason
1093                  * to forbid "git merge" into a branch yet to be born.
1094                  * We do the same for "git pull".
1095                  */
1096                 if (argc != 1)
1097                         die(_("Can merge only exactly one commit into "
1098                                 "empty head"));
1099                 if (squash)
1100                         die(_("Squash commit into empty head not supported yet"));
1101                 if (!allow_fast_forward)
1102                         die(_("Non-fast-forward commit does not make sense into "
1103                             "an empty head"));
1104                 remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT);
1105                 if (!remote_head)
1106                         die(_("%s - not something we can merge"), argv[0]);
1107                 read_empty(remote_head->sha1, 0);
1108                 update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
1109                                 DIE_ON_ERR);
1110                 return 0;
1111         } else {
1112                 struct strbuf merge_names = STRBUF_INIT;
1113
1114                 /* We are invoked directly as the first-class UI. */
1115                 head_arg = "HEAD";
1116
1117                 /*
1118                  * All the rest are the commits being merged;
1119                  * prepare the standard merge summary message to
1120                  * be appended to the given message.  If remote
1121                  * is invalid we will die later in the common
1122                  * codepath so we discard the error in this
1123                  * loop.
1124                  */
1125                 for (i = 0; i < argc; i++)
1126                         merge_name(argv[i], &merge_names);
1127
1128                 if (!have_message || shortlog_len) {
1129                         fmt_merge_msg(&merge_names, &merge_msg, !have_message,
1130                                       shortlog_len);
1131                         if (merge_msg.len)
1132                                 strbuf_setlen(&merge_msg, merge_msg.len - 1);
1133                 }
1134         }
1135
1136         if (head_invalid || !argc)
1137                 usage_with_options(builtin_merge_usage,
1138                         builtin_merge_options);
1139
1140         strbuf_addstr(&buf, "merge");
1141         for (i = 0; i < argc; i++)
1142                 strbuf_addf(&buf, " %s", argv[i]);
1143         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1144         strbuf_reset(&buf);
1145
1146         for (i = 0; i < argc; i++) {
1147                 struct object *o;
1148                 struct commit *commit;
1149
1150                 o = peel_to_type(argv[i], 0, NULL, OBJ_COMMIT);
1151                 if (!o)
1152                         die(_("%s - not something we can merge"), argv[i]);
1153                 commit = lookup_commit(o->sha1);
1154                 commit->util = (void *)argv[i];
1155                 remotes = &commit_list_insert(commit, remotes)->next;
1156
1157                 strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
1158                 setenv(buf.buf, argv[i], 1);
1159                 strbuf_reset(&buf);
1160         }
1161
1162         if (!use_strategies) {
1163                 if (!remoteheads->next)
1164                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1165                 else
1166                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1167         }
1168
1169         for (i = 0; i < use_strategies_nr; i++) {
1170                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
1171                         allow_fast_forward = 0;
1172                 if (use_strategies[i]->attr & NO_TRIVIAL)
1173                         allow_trivial = 0;
1174         }
1175
1176         if (!remoteheads->next)
1177                 common = get_merge_bases(lookup_commit(head),
1178                                 remoteheads->item, 1);
1179         else {
1180                 struct commit_list *list = remoteheads;
1181                 commit_list_insert(lookup_commit(head), &list);
1182                 common = get_octopus_merge_bases(list);
1183                 free(list);
1184         }
1185
1186         update_ref("updating ORIG_HEAD", "ORIG_HEAD", head, NULL, 0,
1187                 DIE_ON_ERR);
1188
1189         if (!common)
1190                 ; /* No common ancestors found. We need a real merge. */
1191         else if (!remoteheads->next && !common->next &&
1192                         common->item == remoteheads->item) {
1193                 /*
1194                  * If head can reach all the merge then we are up to date.
1195                  * but first the most common case of merging one remote.
1196                  */
1197                 finish_up_to_date("Already up-to-date.");
1198                 return 0;
1199         } else if (allow_fast_forward && !remoteheads->next &&
1200                         !common->next &&
1201                         !hashcmp(common->item->object.sha1, head)) {
1202                 /* Again the most common case of merging one remote. */
1203                 struct strbuf msg = STRBUF_INIT;
1204                 struct object *o;
1205                 char hex[41];
1206
1207                 strcpy(hex, find_unique_abbrev(head, DEFAULT_ABBREV));
1208
1209                 if (verbosity >= 0)
1210                         printf(_("Updating %s..%s\n"),
1211                                 hex,
1212                                 find_unique_abbrev(remoteheads->item->object.sha1,
1213                                 DEFAULT_ABBREV));
1214                 strbuf_addstr(&msg, "Fast-forward");
1215                 if (have_message)
1216                         strbuf_addstr(&msg,
1217                                 " (no commit created; -m option ignored)");
1218                 o = peel_to_type(sha1_to_hex(remoteheads->item->object.sha1),
1219                         0, NULL, OBJ_COMMIT);
1220                 if (!o)
1221                         return 1;
1222
1223                 if (checkout_fast_forward(head, remoteheads->item->object.sha1))
1224                         return 1;
1225
1226                 finish(o->sha1, msg.buf);
1227                 drop_save();
1228                 return 0;
1229         } else if (!remoteheads->next && common->next)
1230                 ;
1231                 /*
1232                  * We are not doing octopus and not fast-forward.  Need
1233                  * a real merge.
1234                  */
1235         else if (!remoteheads->next && !common->next && option_commit) {
1236                 /*
1237                  * We are not doing octopus, not fast-forward, and have
1238                  * only one common.
1239                  */
1240                 refresh_cache(REFRESH_QUIET);
1241                 if (allow_trivial && !fast_forward_only) {
1242                         /* See if it is really trivial. */
1243                         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1244                         printf(_("Trying really trivial in-index merge...\n"));
1245                         if (!read_tree_trivial(common->item->object.sha1,
1246                                         head, remoteheads->item->object.sha1))
1247                                 return merge_trivial();
1248                         printf(_("Nope.\n"));
1249                 }
1250         } else {
1251                 /*
1252                  * An octopus.  If we can reach all the remote we are up
1253                  * to date.
1254                  */
1255                 int up_to_date = 1;
1256                 struct commit_list *j;
1257
1258                 for (j = remoteheads; j; j = j->next) {
1259                         struct commit_list *common_one;
1260
1261                         /*
1262                          * Here we *have* to calculate the individual
1263                          * merge_bases again, otherwise "git merge HEAD^
1264                          * HEAD^^" would be missed.
1265                          */
1266                         common_one = get_merge_bases(lookup_commit(head),
1267                                 j->item, 1);
1268                         if (hashcmp(common_one->item->object.sha1,
1269                                 j->item->object.sha1)) {
1270                                 up_to_date = 0;
1271                                 break;
1272                         }
1273                 }
1274                 if (up_to_date) {
1275                         finish_up_to_date("Already up-to-date. Yeeah!");
1276                         return 0;
1277                 }
1278         }
1279
1280         if (fast_forward_only)
1281                 die(_("Not possible to fast-forward, aborting."));
1282
1283         /* We are going to make a new commit. */
1284         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1285
1286         /*
1287          * At this point, we need a real merge.  No matter what strategy
1288          * we use, it would operate on the index, possibly affecting the
1289          * working tree, and when resolved cleanly, have the desired
1290          * tree in the index -- this means that the index must be in
1291          * sync with the head commit.  The strategies are responsible
1292          * to ensure this.
1293          */
1294         if (use_strategies_nr != 1) {
1295                 /*
1296                  * Stash away the local changes so that we can try more
1297                  * than one.
1298                  */
1299                 save_state();
1300         } else {
1301                 memcpy(stash, null_sha1, 20);
1302         }
1303
1304         for (i = 0; i < use_strategies_nr; i++) {
1305                 int ret;
1306                 if (i) {
1307                         printf(_("Rewinding the tree to pristine...\n"));
1308                         restore_state();
1309                 }
1310                 if (use_strategies_nr != 1)
1311                         printf(_("Trying merge strategy %s...\n"),
1312                                 use_strategies[i]->name);
1313                 /*
1314                  * Remember which strategy left the state in the working
1315                  * tree.
1316                  */
1317                 wt_strategy = use_strategies[i]->name;
1318
1319                 ret = try_merge_strategy(use_strategies[i]->name,
1320                         common, head_arg);
1321                 if (!option_commit && !ret) {
1322                         merge_was_ok = 1;
1323                         /*
1324                          * This is necessary here just to avoid writing
1325                          * the tree, but later we will *not* exit with
1326                          * status code 1 because merge_was_ok is set.
1327                          */
1328                         ret = 1;
1329                 }
1330
1331                 if (ret) {
1332                         /*
1333                          * The backend exits with 1 when conflicts are
1334                          * left to be resolved, with 2 when it does not
1335                          * handle the given merge at all.
1336                          */
1337                         if (ret == 1) {
1338                                 int cnt = evaluate_result();
1339
1340                                 if (best_cnt <= 0 || cnt <= best_cnt) {
1341                                         best_strategy = use_strategies[i]->name;
1342                                         best_cnt = cnt;
1343                                 }
1344                         }
1345                         if (merge_was_ok)
1346                                 break;
1347                         else
1348                                 continue;
1349                 }
1350
1351                 /* Automerge succeeded. */
1352                 write_tree_trivial(result_tree);
1353                 automerge_was_ok = 1;
1354                 break;
1355         }
1356
1357         /*
1358          * If we have a resulting tree, that means the strategy module
1359          * auto resolved the merge cleanly.
1360          */
1361         if (automerge_was_ok)
1362                 return finish_automerge(common, result_tree, wt_strategy);
1363
1364         /*
1365          * Pick the result from the best strategy and have the user fix
1366          * it up.
1367          */
1368         if (!best_strategy) {
1369                 restore_state();
1370                 if (use_strategies_nr > 1)
1371                         fprintf(stderr,
1372                                 _("No merge strategy handled the merge.\n"));
1373                 else
1374                         fprintf(stderr, _("Merge with strategy %s failed.\n"),
1375                                 use_strategies[0]->name);
1376                 return 2;
1377         } else if (best_strategy == wt_strategy)
1378                 ; /* We already have its result in the working tree. */
1379         else {
1380                 printf(_("Rewinding the tree to pristine...\n"));
1381                 restore_state();
1382                 printf(_("Using the %s to prepare resolving by hand.\n"),
1383                         best_strategy);
1384                 try_merge_strategy(best_strategy, common, head_arg);
1385         }
1386
1387         if (squash)
1388                 finish(NULL, NULL);
1389         else {
1390                 int fd;
1391                 struct commit_list *j;
1392
1393                 for (j = remoteheads; j; j = j->next)
1394                         strbuf_addf(&buf, "%s\n",
1395                                 sha1_to_hex(j->item->object.sha1));
1396                 fd = open(git_path("MERGE_HEAD"), O_WRONLY | O_CREAT, 0666);
1397                 if (fd < 0)
1398                         die_errno(_("Could not open '%s' for writing"),
1399                                   git_path("MERGE_HEAD"));
1400                 if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1401                         die_errno(_("Could not write to '%s'"), git_path("MERGE_HEAD"));
1402                 close(fd);
1403                 strbuf_addch(&merge_msg, '\n');
1404                 write_merge_msg();
1405                 fd = open(git_path("MERGE_MODE"), O_WRONLY | O_CREAT | O_TRUNC, 0666);
1406                 if (fd < 0)
1407                         die_errno(_("Could not open '%s' for writing"),
1408                                   git_path("MERGE_MODE"));
1409                 strbuf_reset(&buf);
1410                 if (!allow_fast_forward)
1411                         strbuf_addf(&buf, "no-ff");
1412                 if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1413                         die_errno(_("Could not write to '%s'"), git_path("MERGE_MODE"));
1414                 close(fd);
1415         }
1416
1417         if (merge_was_ok) {
1418                 fprintf(stderr, _("Automatic merge went well; "
1419                         "stopped before committing as requested\n"));
1420                 return 0;
1421         } else
1422                 return suggest_conflicts(option_renormalize);
1423 }