Merge branch 'nd/ita-cleanup' into maint
[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 "lockfile.h"
13 #include "run-command.h"
14 #include "diff.h"
15 #include "refs.h"
16 #include "commit.h"
17 #include "diffcore.h"
18 #include "revision.h"
19 #include "unpack-trees.h"
20 #include "cache-tree.h"
21 #include "dir.h"
22 #include "utf8.h"
23 #include "log-tree.h"
24 #include "color.h"
25 #include "rerere.h"
26 #include "help.h"
27 #include "merge-recursive.h"
28 #include "resolve-undo.h"
29 #include "remote.h"
30 #include "fmt-merge-msg.h"
31 #include "gpg-interface.h"
32 #include "sequencer.h"
33
34 #define DEFAULT_TWOHEAD (1<<0)
35 #define DEFAULT_OCTOPUS (1<<1)
36 #define NO_FAST_FORWARD (1<<2)
37 #define NO_TRIVIAL      (1<<3)
38
39 struct strategy {
40         const char *name;
41         unsigned attr;
42 };
43
44 static const char * const builtin_merge_usage[] = {
45         N_("git merge [<options>] [<commit>...]"),
46         N_("git merge [<options>] <msg> HEAD <commit>"),
47         N_("git merge --abort"),
48         NULL
49 };
50
51 static int show_diffstat = 1, shortlog_len = -1, squash;
52 static int option_commit = 1;
53 static int option_edit = -1;
54 static int allow_trivial = 1, have_message, verify_signatures;
55 static int overwrite_ignore = 1;
56 static struct strbuf merge_msg = STRBUF_INIT;
57 static struct strategy **use_strategies;
58 static size_t use_strategies_nr, use_strategies_alloc;
59 static const char **xopts;
60 static size_t xopts_nr, xopts_alloc;
61 static const char *branch;
62 static char *branch_mergeoptions;
63 static int option_renormalize;
64 static int verbosity;
65 static int allow_rerere_auto;
66 static int abort_current_merge;
67 static int allow_unrelated_histories;
68 static int show_progress = -1;
69 static int default_to_upstream = 1;
70 static const char *sign_commit;
71
72 static struct strategy all_strategy[] = {
73         { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
74         { "octopus",    DEFAULT_OCTOPUS },
75         { "resolve",    0 },
76         { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
77         { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
78 };
79
80 static const char *pull_twohead, *pull_octopus;
81
82 enum ff_type {
83         FF_NO,
84         FF_ALLOW,
85         FF_ONLY
86 };
87
88 static enum ff_type fast_forward = FF_ALLOW;
89
90 static int option_parse_message(const struct option *opt,
91                                 const char *arg, int unset)
92 {
93         struct strbuf *buf = opt->value;
94
95         if (unset)
96                 strbuf_setlen(buf, 0);
97         else if (arg) {
98                 strbuf_addf(buf, "%s%s", buf->len ? "\n\n" : "", arg);
99                 have_message = 1;
100         } else
101                 return error(_("switch `m' requires a value"));
102         return 0;
103 }
104
105 static struct strategy *get_strategy(const char *name)
106 {
107         int i;
108         struct strategy *ret;
109         static struct cmdnames main_cmds, other_cmds;
110         static int loaded;
111
112         if (!name)
113                 return NULL;
114
115         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
116                 if (!strcmp(name, all_strategy[i].name))
117                         return &all_strategy[i];
118
119         if (!loaded) {
120                 struct cmdnames not_strategies;
121                 loaded = 1;
122
123                 memset(&not_strategies, 0, sizeof(struct cmdnames));
124                 load_command_list("git-merge-", &main_cmds, &other_cmds);
125                 for (i = 0; i < main_cmds.cnt; i++) {
126                         int j, found = 0;
127                         struct cmdname *ent = main_cmds.names[i];
128                         for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
129                                 if (!strncmp(ent->name, all_strategy[j].name, ent->len)
130                                                 && !all_strategy[j].name[ent->len])
131                                         found = 1;
132                         if (!found)
133                                 add_cmdname(&not_strategies, ent->name, ent->len);
134                 }
135                 exclude_cmds(&main_cmds, &not_strategies);
136         }
137         if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
138                 fprintf(stderr, _("Could not find merge strategy '%s'.\n"), name);
139                 fprintf(stderr, _("Available strategies are:"));
140                 for (i = 0; i < main_cmds.cnt; i++)
141                         fprintf(stderr, " %s", main_cmds.names[i]->name);
142                 fprintf(stderr, ".\n");
143                 if (other_cmds.cnt) {
144                         fprintf(stderr, _("Available custom strategies are:"));
145                         for (i = 0; i < other_cmds.cnt; i++)
146                                 fprintf(stderr, " %s", other_cmds.names[i]->name);
147                         fprintf(stderr, ".\n");
148                 }
149                 exit(1);
150         }
151
152         ret = xcalloc(1, sizeof(struct strategy));
153         ret->name = xstrdup(name);
154         ret->attr = NO_TRIVIAL;
155         return ret;
156 }
157
158 static void append_strategy(struct strategy *s)
159 {
160         ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
161         use_strategies[use_strategies_nr++] = s;
162 }
163
164 static int option_parse_strategy(const struct option *opt,
165                                  const char *name, int unset)
166 {
167         if (unset)
168                 return 0;
169
170         append_strategy(get_strategy(name));
171         return 0;
172 }
173
174 static int option_parse_x(const struct option *opt,
175                           const char *arg, int unset)
176 {
177         if (unset)
178                 return 0;
179
180         ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
181         xopts[xopts_nr++] = xstrdup(arg);
182         return 0;
183 }
184
185 static int option_parse_n(const struct option *opt,
186                           const char *arg, int unset)
187 {
188         show_diffstat = unset;
189         return 0;
190 }
191
192 static struct option builtin_merge_options[] = {
193         { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
194                 N_("do not show a diffstat at the end of the merge"),
195                 PARSE_OPT_NOARG, option_parse_n },
196         OPT_BOOL(0, "stat", &show_diffstat,
197                 N_("show a diffstat at the end of the merge")),
198         OPT_BOOL(0, "summary", &show_diffstat, N_("(synonym to --stat)")),
199         { OPTION_INTEGER, 0, "log", &shortlog_len, N_("n"),
200           N_("add (at most <n>) entries from shortlog to merge commit message"),
201           PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
202         OPT_BOOL(0, "squash", &squash,
203                 N_("create a single commit instead of doing a merge")),
204         OPT_BOOL(0, "commit", &option_commit,
205                 N_("perform a commit if the merge succeeds (default)")),
206         OPT_BOOL('e', "edit", &option_edit,
207                 N_("edit message before committing")),
208         OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
209         { OPTION_SET_INT, 0, "ff-only", &fast_forward, NULL,
210                 N_("abort if fast-forward is not possible"),
211                 PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, FF_ONLY },
212         OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
213         OPT_BOOL(0, "verify-signatures", &verify_signatures,
214                 N_("Verify that the named commit has a valid GPG signature")),
215         OPT_CALLBACK('s', "strategy", &use_strategies, N_("strategy"),
216                 N_("merge strategy to use"), option_parse_strategy),
217         OPT_CALLBACK('X', "strategy-option", &xopts, N_("option=value"),
218                 N_("option for selected merge strategy"), option_parse_x),
219         OPT_CALLBACK('m', "message", &merge_msg, N_("message"),
220                 N_("merge commit message (for a non-fast-forward merge)"),
221                 option_parse_message),
222         OPT__VERBOSITY(&verbosity),
223         OPT_BOOL(0, "abort", &abort_current_merge,
224                 N_("abort the current in-progress merge")),
225         OPT_BOOL(0, "allow-unrelated-histories", &allow_unrelated_histories,
226                  N_("allow merging unrelated histories")),
227         OPT_SET_INT(0, "progress", &show_progress, N_("force progress reporting"), 1),
228         { OPTION_STRING, 'S', "gpg-sign", &sign_commit, N_("key-id"),
229           N_("GPG sign commit"), PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
230         OPT_BOOL(0, "overwrite-ignore", &overwrite_ignore, N_("update ignored files (default)")),
231         OPT_END()
232 };
233
234 /* Cleans up metadata that is uninteresting after a succeeded merge. */
235 static void drop_save(void)
236 {
237         unlink(git_path_merge_head());
238         unlink(git_path_merge_msg());
239         unlink(git_path_merge_mode());
240 }
241
242 static int save_state(unsigned char *stash)
243 {
244         int len;
245         struct child_process cp = CHILD_PROCESS_INIT;
246         struct strbuf buffer = STRBUF_INIT;
247         const char *argv[] = {"stash", "create", NULL};
248
249         cp.argv = argv;
250         cp.out = -1;
251         cp.git_cmd = 1;
252
253         if (start_command(&cp))
254                 die(_("could not run stash."));
255         len = strbuf_read(&buffer, cp.out, 1024);
256         close(cp.out);
257
258         if (finish_command(&cp) || len < 0)
259                 die(_("stash failed"));
260         else if (!len)          /* no changes */
261                 return -1;
262         strbuf_setlen(&buffer, buffer.len-1);
263         if (get_sha1(buffer.buf, stash))
264                 die(_("not a valid object: %s"), buffer.buf);
265         return 0;
266 }
267
268 static void read_empty(unsigned const char *sha1, int verbose)
269 {
270         int i = 0;
271         const char *args[7];
272
273         args[i++] = "read-tree";
274         if (verbose)
275                 args[i++] = "-v";
276         args[i++] = "-m";
277         args[i++] = "-u";
278         args[i++] = EMPTY_TREE_SHA1_HEX;
279         args[i++] = sha1_to_hex(sha1);
280         args[i] = NULL;
281
282         if (run_command_v_opt(args, RUN_GIT_CMD))
283                 die(_("read-tree failed"));
284 }
285
286 static void reset_hard(unsigned const char *sha1, int verbose)
287 {
288         int i = 0;
289         const char *args[6];
290
291         args[i++] = "read-tree";
292         if (verbose)
293                 args[i++] = "-v";
294         args[i++] = "--reset";
295         args[i++] = "-u";
296         args[i++] = sha1_to_hex(sha1);
297         args[i] = NULL;
298
299         if (run_command_v_opt(args, RUN_GIT_CMD))
300                 die(_("read-tree failed"));
301 }
302
303 static void restore_state(const unsigned char *head,
304                           const unsigned char *stash)
305 {
306         struct strbuf sb = STRBUF_INIT;
307         const char *args[] = { "stash", "apply", NULL, NULL };
308
309         if (is_null_sha1(stash))
310                 return;
311
312         reset_hard(head, 1);
313
314         args[2] = sha1_to_hex(stash);
315
316         /*
317          * It is OK to ignore error here, for example when there was
318          * nothing to restore.
319          */
320         run_command_v_opt(args, RUN_GIT_CMD);
321
322         strbuf_release(&sb);
323         refresh_cache(REFRESH_QUIET);
324 }
325
326 /* This is called when no merge was necessary. */
327 static void finish_up_to_date(const char *msg)
328 {
329         if (verbosity >= 0)
330                 printf("%s%s\n", squash ? _(" (nothing to squash)") : "", msg);
331         drop_save();
332 }
333
334 static void squash_message(struct commit *commit, struct commit_list *remoteheads)
335 {
336         struct rev_info rev;
337         struct strbuf out = STRBUF_INIT;
338         struct commit_list *j;
339         const char *filename;
340         int fd;
341         struct pretty_print_context ctx = {0};
342
343         printf(_("Squash commit -- not updating HEAD\n"));
344         filename = git_path_squash_msg();
345         fd = open(filename, O_WRONLY | O_CREAT, 0666);
346         if (fd < 0)
347                 die_errno(_("Could not write to '%s'"), filename);
348
349         init_revisions(&rev, NULL);
350         rev.ignore_merges = 1;
351         rev.commit_format = CMIT_FMT_MEDIUM;
352
353         commit->object.flags |= UNINTERESTING;
354         add_pending_object(&rev, &commit->object, NULL);
355
356         for (j = remoteheads; j; j = j->next)
357                 add_pending_object(&rev, &j->item->object, NULL);
358
359         setup_revisions(0, NULL, &rev, NULL);
360         if (prepare_revision_walk(&rev))
361                 die(_("revision walk setup failed"));
362
363         ctx.abbrev = rev.abbrev;
364         ctx.date_mode = rev.date_mode;
365         ctx.fmt = rev.commit_format;
366
367         strbuf_addstr(&out, "Squashed commit of the following:\n");
368         while ((commit = get_revision(&rev)) != NULL) {
369                 strbuf_addch(&out, '\n');
370                 strbuf_addf(&out, "commit %s\n",
371                         oid_to_hex(&commit->object.oid));
372                 pretty_print_commit(&ctx, commit, &out);
373         }
374         if (write_in_full(fd, out.buf, out.len) != out.len)
375                 die_errno(_("Writing SQUASH_MSG"));
376         if (close(fd))
377                 die_errno(_("Finishing SQUASH_MSG"));
378         strbuf_release(&out);
379 }
380
381 static void finish(struct commit *head_commit,
382                    struct commit_list *remoteheads,
383                    const unsigned char *new_head, const char *msg)
384 {
385         struct strbuf reflog_message = STRBUF_INIT;
386         const unsigned char *head = head_commit->object.oid.hash;
387
388         if (!msg)
389                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
390         else {
391                 if (verbosity >= 0)
392                         printf("%s\n", msg);
393                 strbuf_addf(&reflog_message, "%s: %s",
394                         getenv("GIT_REFLOG_ACTION"), msg);
395         }
396         if (squash) {
397                 squash_message(head_commit, remoteheads);
398         } else {
399                 if (verbosity >= 0 && !merge_msg.len)
400                         printf(_("No merge message -- not updating HEAD\n"));
401                 else {
402                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
403                         update_ref(reflog_message.buf, "HEAD",
404                                 new_head, head, 0,
405                                 UPDATE_REFS_DIE_ON_ERR);
406                         /*
407                          * We ignore errors in 'gc --auto', since the
408                          * user should see them.
409                          */
410                         close_all_packs();
411                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
412                 }
413         }
414         if (new_head && show_diffstat) {
415                 struct diff_options opts;
416                 diff_setup(&opts);
417                 opts.stat_width = -1; /* use full terminal width */
418                 opts.stat_graph_width = -1; /* respect statGraphWidth config */
419                 opts.output_format |=
420                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
421                 opts.detect_rename = DIFF_DETECT_RENAME;
422                 diff_setup_done(&opts);
423                 diff_tree_sha1(head, new_head, "", &opts);
424                 diffcore_std(&opts);
425                 diff_flush(&opts);
426         }
427
428         /* Run a post-merge hook */
429         run_hook_le(NULL, "post-merge", squash ? "1" : "0", NULL);
430
431         strbuf_release(&reflog_message);
432 }
433
434 /* Get the name for the merge commit's message. */
435 static void merge_name(const char *remote, struct strbuf *msg)
436 {
437         struct commit *remote_head;
438         unsigned char branch_head[20];
439         struct strbuf buf = STRBUF_INIT;
440         struct strbuf bname = STRBUF_INIT;
441         const char *ptr;
442         char *found_ref;
443         int len, early;
444
445         strbuf_branchname(&bname, remote);
446         remote = bname.buf;
447
448         memset(branch_head, 0, sizeof(branch_head));
449         remote_head = get_merge_parent(remote);
450         if (!remote_head)
451                 die(_("'%s' does not point to a commit"), remote);
452
453         if (dwim_ref(remote, strlen(remote), branch_head, &found_ref) > 0) {
454                 if (starts_with(found_ref, "refs/heads/")) {
455                         strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
456                                     sha1_to_hex(branch_head), remote);
457                         goto cleanup;
458                 }
459                 if (starts_with(found_ref, "refs/tags/")) {
460                         strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
461                                     sha1_to_hex(branch_head), remote);
462                         goto cleanup;
463                 }
464                 if (starts_with(found_ref, "refs/remotes/")) {
465                         strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
466                                     sha1_to_hex(branch_head), remote);
467                         goto cleanup;
468                 }
469         }
470
471         /* See if remote matches <name>^^^.. or <name>~<number> */
472         for (len = 0, ptr = remote + strlen(remote);
473              remote < ptr && ptr[-1] == '^';
474              ptr--)
475                 len++;
476         if (len)
477                 early = 1;
478         else {
479                 early = 0;
480                 ptr = strrchr(remote, '~');
481                 if (ptr) {
482                         int seen_nonzero = 0;
483
484                         len++; /* count ~ */
485                         while (*++ptr && isdigit(*ptr)) {
486                                 seen_nonzero |= (*ptr != '0');
487                                 len++;
488                         }
489                         if (*ptr)
490                                 len = 0; /* not ...~<number> */
491                         else if (seen_nonzero)
492                                 early = 1;
493                         else if (len == 1)
494                                 early = 1; /* "name~" is "name~1"! */
495                 }
496         }
497         if (len) {
498                 struct strbuf truname = STRBUF_INIT;
499                 strbuf_addf(&truname, "refs/heads/%s", remote);
500                 strbuf_setlen(&truname, truname.len - len);
501                 if (ref_exists(truname.buf)) {
502                         strbuf_addf(msg,
503                                     "%s\t\tbranch '%s'%s of .\n",
504                                     sha1_to_hex(remote_head->object.oid.hash),
505                                     truname.buf + 11,
506                                     (early ? " (early part)" : ""));
507                         strbuf_release(&truname);
508                         goto cleanup;
509                 }
510                 strbuf_release(&truname);
511         }
512
513         if (remote_head->util) {
514                 struct merge_remote_desc *desc;
515                 desc = merge_remote_util(remote_head);
516                 if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
517                         strbuf_addf(msg, "%s\t\t%s '%s'\n",
518                                     sha1_to_hex(desc->obj->oid.hash),
519                                     typename(desc->obj->type),
520                                     remote);
521                         goto cleanup;
522                 }
523         }
524
525         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
526                 sha1_to_hex(remote_head->object.oid.hash), remote);
527 cleanup:
528         strbuf_release(&buf);
529         strbuf_release(&bname);
530 }
531
532 static void parse_branch_merge_options(char *bmo)
533 {
534         const char **argv;
535         int argc;
536
537         if (!bmo)
538                 return;
539         argc = split_cmdline(bmo, &argv);
540         if (argc < 0)
541                 die(_("Bad branch.%s.mergeoptions string: %s"), branch,
542                     split_cmdline_strerror(argc));
543         REALLOC_ARRAY(argv, argc + 2);
544         memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
545         argc++;
546         argv[0] = "branch.*.mergeoptions";
547         parse_options(argc, argv, NULL, builtin_merge_options,
548                       builtin_merge_usage, 0);
549         free(argv);
550 }
551
552 static int git_merge_config(const char *k, const char *v, void *cb)
553 {
554         int status;
555
556         if (branch && starts_with(k, "branch.") &&
557                 starts_with(k + 7, branch) &&
558                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
559                 free(branch_mergeoptions);
560                 branch_mergeoptions = xstrdup(v);
561                 return 0;
562         }
563
564         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
565                 show_diffstat = git_config_bool(k, v);
566         else if (!strcmp(k, "pull.twohead"))
567                 return git_config_string(&pull_twohead, k, v);
568         else if (!strcmp(k, "pull.octopus"))
569                 return git_config_string(&pull_octopus, k, v);
570         else if (!strcmp(k, "merge.renormalize"))
571                 option_renormalize = git_config_bool(k, v);
572         else if (!strcmp(k, "merge.ff")) {
573                 int boolval = git_config_maybe_bool(k, v);
574                 if (0 <= boolval) {
575                         fast_forward = boolval ? FF_ALLOW : FF_NO;
576                 } else if (v && !strcmp(v, "only")) {
577                         fast_forward = FF_ONLY;
578                 } /* do not barf on values from future versions of git */
579                 return 0;
580         } else if (!strcmp(k, "merge.defaulttoupstream")) {
581                 default_to_upstream = git_config_bool(k, v);
582                 return 0;
583         } else if (!strcmp(k, "commit.gpgsign")) {
584                 sign_commit = git_config_bool(k, v) ? "" : NULL;
585                 return 0;
586         }
587
588         status = fmt_merge_msg_config(k, v, cb);
589         if (status)
590                 return status;
591         status = git_gpg_config(k, v, NULL);
592         if (status)
593                 return status;
594         return git_diff_ui_config(k, v, cb);
595 }
596
597 static int read_tree_trivial(unsigned char *common, unsigned char *head,
598                              unsigned char *one)
599 {
600         int i, nr_trees = 0;
601         struct tree *trees[MAX_UNPACK_TREES];
602         struct tree_desc t[MAX_UNPACK_TREES];
603         struct unpack_trees_options opts;
604
605         memset(&opts, 0, sizeof(opts));
606         opts.head_idx = 2;
607         opts.src_index = &the_index;
608         opts.dst_index = &the_index;
609         opts.update = 1;
610         opts.verbose_update = 1;
611         opts.trivial_merges_only = 1;
612         opts.merge = 1;
613         trees[nr_trees] = parse_tree_indirect(common);
614         if (!trees[nr_trees++])
615                 return -1;
616         trees[nr_trees] = parse_tree_indirect(head);
617         if (!trees[nr_trees++])
618                 return -1;
619         trees[nr_trees] = parse_tree_indirect(one);
620         if (!trees[nr_trees++])
621                 return -1;
622         opts.fn = threeway_merge;
623         cache_tree_free(&active_cache_tree);
624         for (i = 0; i < nr_trees; i++) {
625                 parse_tree(trees[i]);
626                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
627         }
628         if (unpack_trees(nr_trees, t, &opts))
629                 return -1;
630         return 0;
631 }
632
633 static void write_tree_trivial(unsigned char *sha1)
634 {
635         if (write_cache_as_tree(sha1, 0, NULL))
636                 die(_("git write-tree failed to write a tree"));
637 }
638
639 static int try_merge_strategy(const char *strategy, struct commit_list *common,
640                               struct commit_list *remoteheads,
641                               struct commit *head, const char *head_arg)
642 {
643         static struct lock_file lock;
644
645         hold_locked_index(&lock, 1);
646         refresh_cache(REFRESH_QUIET);
647         if (active_cache_changed &&
648             write_locked_index(&the_index, &lock, COMMIT_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 commit_list *reversed = NULL;
656                 struct merge_options o;
657                 struct commit_list *j;
658
659                 if (remoteheads->next) {
660                         error(_("Not handling anything other than two heads merge."));
661                         return 2;
662                 }
663
664                 init_merge_options(&o);
665                 if (!strcmp(strategy, "subtree"))
666                         o.subtree_shift = "";
667
668                 o.renormalize = option_renormalize;
669                 o.show_rename_progress =
670                         show_progress == -1 ? isatty(2) : show_progress;
671
672                 for (x = 0; x < xopts_nr; x++)
673                         if (parse_merge_opt(&o, xopts[x]))
674                                 die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
675
676                 o.branch1 = head_arg;
677                 o.branch2 = merge_remote_util(remoteheads->item)->name;
678
679                 for (j = common; j; j = j->next)
680                         commit_list_insert(j->item, &reversed);
681
682                 hold_locked_index(&lock, 1);
683                 clean = merge_recursive(&o, head,
684                                 remoteheads->item, reversed, &result);
685                 if (active_cache_changed &&
686                     write_locked_index(&the_index, &lock, COMMIT_LOCK))
687                         die (_("unable to write %s"), get_index_file());
688                 rollback_lock_file(&lock);
689                 return clean ? 0 : 1;
690         } else {
691                 return try_merge_command(strategy, xopts_nr, xopts,
692                                                 common, head_arg, remoteheads);
693         }
694 }
695
696 static void count_diff_files(struct diff_queue_struct *q,
697                              struct diff_options *opt, void *data)
698 {
699         int *count = data;
700
701         (*count) += q->nr;
702 }
703
704 static int count_unmerged_entries(void)
705 {
706         int i, ret = 0;
707
708         for (i = 0; i < active_nr; i++)
709                 if (ce_stage(active_cache[i]))
710                         ret++;
711
712         return ret;
713 }
714
715 static void split_merge_strategies(const char *string, struct strategy **list,
716                                    int *nr, int *alloc)
717 {
718         char *p, *q, *buf;
719
720         if (!string)
721                 return;
722
723         buf = xstrdup(string);
724         q = buf;
725         for (;;) {
726                 p = strchr(q, ' ');
727                 if (!p) {
728                         ALLOC_GROW(*list, *nr + 1, *alloc);
729                         (*list)[(*nr)++].name = xstrdup(q);
730                         free(buf);
731                         return;
732                 } else {
733                         *p = '\0';
734                         ALLOC_GROW(*list, *nr + 1, *alloc);
735                         (*list)[(*nr)++].name = xstrdup(q);
736                         q = ++p;
737                 }
738         }
739 }
740
741 static void add_strategies(const char *string, unsigned attr)
742 {
743         struct strategy *list = NULL;
744         int list_alloc = 0, list_nr = 0, i;
745
746         memset(&list, 0, sizeof(list));
747         split_merge_strategies(string, &list, &list_nr, &list_alloc);
748         if (list) {
749                 for (i = 0; i < list_nr; i++)
750                         append_strategy(get_strategy(list[i].name));
751                 return;
752         }
753         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
754                 if (all_strategy[i].attr & attr)
755                         append_strategy(&all_strategy[i]);
756
757 }
758
759 static void write_merge_msg(struct strbuf *msg)
760 {
761         const char *filename = git_path_merge_msg();
762         int fd = open(filename, O_WRONLY | O_CREAT, 0666);
763         if (fd < 0)
764                 die_errno(_("Could not open '%s' for writing"),
765                           filename);
766         if (write_in_full(fd, msg->buf, msg->len) != msg->len)
767                 die_errno(_("Could not write to '%s'"), filename);
768         close(fd);
769 }
770
771 static void read_merge_msg(struct strbuf *msg)
772 {
773         const char *filename = git_path_merge_msg();
774         strbuf_reset(msg);
775         if (strbuf_read_file(msg, filename, 0) < 0)
776                 die_errno(_("Could not read from '%s'"), filename);
777 }
778
779 static void write_merge_state(struct commit_list *);
780 static void abort_commit(struct commit_list *remoteheads, const char *err_msg)
781 {
782         if (err_msg)
783                 error("%s", err_msg);
784         fprintf(stderr,
785                 _("Not committing merge; use 'git commit' to complete the merge.\n"));
786         write_merge_state(remoteheads);
787         exit(1);
788 }
789
790 static const char merge_editor_comment[] =
791 N_("Please enter a commit message to explain why this merge is necessary,\n"
792    "especially if it merges an updated upstream into a topic branch.\n"
793    "\n"
794    "Lines starting with '%c' will be ignored, and an empty message aborts\n"
795    "the commit.\n");
796
797 static void prepare_to_commit(struct commit_list *remoteheads)
798 {
799         struct strbuf msg = STRBUF_INIT;
800         strbuf_addbuf(&msg, &merge_msg);
801         strbuf_addch(&msg, '\n');
802         if (0 < option_edit)
803                 strbuf_commented_addf(&msg, _(merge_editor_comment), comment_line_char);
804         write_merge_msg(&msg);
805         if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
806                             git_path_merge_msg(), "merge", NULL))
807                 abort_commit(remoteheads, NULL);
808         if (0 < option_edit) {
809                 if (launch_editor(git_path_merge_msg(), NULL, NULL))
810                         abort_commit(remoteheads, NULL);
811         }
812         read_merge_msg(&msg);
813         strbuf_stripspace(&msg, 0 < option_edit);
814         if (!msg.len)
815                 abort_commit(remoteheads, _("Empty commit message."));
816         strbuf_release(&merge_msg);
817         strbuf_addbuf(&merge_msg, &msg);
818         strbuf_release(&msg);
819 }
820
821 static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
822 {
823         unsigned char result_tree[20], result_commit[20];
824         struct commit_list *parents, **pptr = &parents;
825         static struct lock_file lock;
826
827         hold_locked_index(&lock, 1);
828         refresh_cache(REFRESH_QUIET);
829         if (active_cache_changed &&
830             write_locked_index(&the_index, &lock, COMMIT_LOCK))
831                 return error(_("Unable to write index."));
832         rollback_lock_file(&lock);
833
834         write_tree_trivial(result_tree);
835         printf(_("Wonderful.\n"));
836         pptr = commit_list_append(head, pptr);
837         pptr = commit_list_append(remoteheads->item, pptr);
838         prepare_to_commit(remoteheads);
839         if (commit_tree(merge_msg.buf, merge_msg.len, result_tree, parents,
840                         result_commit, NULL, sign_commit))
841                 die(_("failed to write commit object"));
842         finish(head, remoteheads, result_commit, "In-index merge");
843         drop_save();
844         return 0;
845 }
846
847 static int finish_automerge(struct commit *head,
848                             int head_subsumed,
849                             struct commit_list *common,
850                             struct commit_list *remoteheads,
851                             unsigned char *result_tree,
852                             const char *wt_strategy)
853 {
854         struct commit_list *parents = NULL;
855         struct strbuf buf = STRBUF_INIT;
856         unsigned char result_commit[20];
857
858         free_commit_list(common);
859         parents = remoteheads;
860         if (!head_subsumed || fast_forward == FF_NO)
861                 commit_list_insert(head, &parents);
862         strbuf_addch(&merge_msg, '\n');
863         prepare_to_commit(remoteheads);
864         if (commit_tree(merge_msg.buf, merge_msg.len, result_tree, parents,
865                         result_commit, NULL, sign_commit))
866                 die(_("failed to write commit object"));
867         strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
868         finish(head, remoteheads, result_commit, buf.buf);
869         strbuf_release(&buf);
870         drop_save();
871         return 0;
872 }
873
874 static int suggest_conflicts(void)
875 {
876         const char *filename;
877         FILE *fp;
878         struct strbuf msgbuf = STRBUF_INIT;
879
880         filename = git_path_merge_msg();
881         fp = fopen(filename, "a");
882         if (!fp)
883                 die_errno(_("Could not open '%s' for writing"), filename);
884
885         append_conflicts_hint(&msgbuf);
886         fputs(msgbuf.buf, fp);
887         strbuf_release(&msgbuf);
888         fclose(fp);
889         rerere(allow_rerere_auto);
890         printf(_("Automatic merge failed; "
891                         "fix conflicts and then commit the result.\n"));
892         return 1;
893 }
894
895 static struct commit *is_old_style_invocation(int argc, const char **argv,
896                                               const unsigned char *head)
897 {
898         struct commit *second_token = NULL;
899         if (argc > 2) {
900                 unsigned char second_sha1[20];
901
902                 if (get_sha1(argv[1], second_sha1))
903                         return NULL;
904                 second_token = lookup_commit_reference_gently(second_sha1, 0);
905                 if (!second_token)
906                         die(_("'%s' is not a commit"), argv[1]);
907                 if (hashcmp(second_token->object.oid.hash, head))
908                         return NULL;
909         }
910         return second_token;
911 }
912
913 static int evaluate_result(void)
914 {
915         int cnt = 0;
916         struct rev_info rev;
917
918         /* Check how many files differ. */
919         init_revisions(&rev, "");
920         setup_revisions(0, NULL, &rev, NULL);
921         rev.diffopt.output_format |=
922                 DIFF_FORMAT_CALLBACK;
923         rev.diffopt.format_callback = count_diff_files;
924         rev.diffopt.format_callback_data = &cnt;
925         run_diff_files(&rev, 0);
926
927         /*
928          * Check how many unmerged entries are
929          * there.
930          */
931         cnt += count_unmerged_entries();
932
933         return cnt;
934 }
935
936 /*
937  * Pretend as if the user told us to merge with the remote-tracking
938  * branch we have for the upstream of the current branch
939  */
940 static int setup_with_upstream(const char ***argv)
941 {
942         struct branch *branch = branch_get(NULL);
943         int i;
944         const char **args;
945
946         if (!branch)
947                 die(_("No current branch."));
948         if (!branch->remote_name)
949                 die(_("No remote for the current branch."));
950         if (!branch->merge_nr)
951                 die(_("No default upstream defined for the current branch."));
952
953         args = xcalloc(st_add(branch->merge_nr, 1), sizeof(char *));
954         for (i = 0; i < branch->merge_nr; i++) {
955                 if (!branch->merge[i]->dst)
956                         die(_("No remote-tracking branch for %s from %s"),
957                             branch->merge[i]->src, branch->remote_name);
958                 args[i] = branch->merge[i]->dst;
959         }
960         args[i] = NULL;
961         *argv = args;
962         return i;
963 }
964
965 static void write_merge_state(struct commit_list *remoteheads)
966 {
967         const char *filename;
968         int fd;
969         struct commit_list *j;
970         struct strbuf buf = STRBUF_INIT;
971
972         for (j = remoteheads; j; j = j->next) {
973                 struct object_id *oid;
974                 struct commit *c = j->item;
975                 if (c->util && merge_remote_util(c)->obj) {
976                         oid = &merge_remote_util(c)->obj->oid;
977                 } else {
978                         oid = &c->object.oid;
979                 }
980                 strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
981         }
982         filename = git_path_merge_head();
983         fd = open(filename, O_WRONLY | O_CREAT, 0666);
984         if (fd < 0)
985                 die_errno(_("Could not open '%s' for writing"), filename);
986         if (write_in_full(fd, buf.buf, buf.len) != buf.len)
987                 die_errno(_("Could not write to '%s'"), filename);
988         close(fd);
989         strbuf_addch(&merge_msg, '\n');
990         write_merge_msg(&merge_msg);
991
992         filename = git_path_merge_mode();
993         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
994         if (fd < 0)
995                 die_errno(_("Could not open '%s' for writing"), filename);
996         strbuf_reset(&buf);
997         if (fast_forward == FF_NO)
998                 strbuf_addf(&buf, "no-ff");
999         if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1000                 die_errno(_("Could not write to '%s'"), filename);
1001         close(fd);
1002 }
1003
1004 static int default_edit_option(void)
1005 {
1006         static const char name[] = "GIT_MERGE_AUTOEDIT";
1007         const char *e = getenv(name);
1008         struct stat st_stdin, st_stdout;
1009
1010         if (have_message)
1011                 /* an explicit -m msg without --[no-]edit */
1012                 return 0;
1013
1014         if (e) {
1015                 int v = git_config_maybe_bool(name, e);
1016                 if (v < 0)
1017                         die("Bad value '%s' in environment '%s'", e, name);
1018                 return v;
1019         }
1020
1021         /* Use editor if stdin and stdout are the same and is a tty */
1022         return (!fstat(0, &st_stdin) &&
1023                 !fstat(1, &st_stdout) &&
1024                 isatty(0) && isatty(1) &&
1025                 st_stdin.st_dev == st_stdout.st_dev &&
1026                 st_stdin.st_ino == st_stdout.st_ino &&
1027                 st_stdin.st_mode == st_stdout.st_mode);
1028 }
1029
1030 static struct commit_list *reduce_parents(struct commit *head_commit,
1031                                           int *head_subsumed,
1032                                           struct commit_list *remoteheads)
1033 {
1034         struct commit_list *parents, **remotes;
1035
1036         /*
1037          * Is the current HEAD reachable from another commit being
1038          * merged?  If so we do not want to record it as a parent of
1039          * the resulting merge, unless --no-ff is given.  We will flip
1040          * this variable to 0 when we find HEAD among the independent
1041          * tips being merged.
1042          */
1043         *head_subsumed = 1;
1044
1045         /* Find what parents to record by checking independent ones. */
1046         parents = reduce_heads(remoteheads);
1047
1048         remoteheads = NULL;
1049         remotes = &remoteheads;
1050         while (parents) {
1051                 struct commit *commit = pop_commit(&parents);
1052                 if (commit == head_commit)
1053                         *head_subsumed = 0;
1054                 else
1055                         remotes = &commit_list_insert(commit, remotes)->next;
1056         }
1057         return remoteheads;
1058 }
1059
1060 static void prepare_merge_message(struct strbuf *merge_names, struct strbuf *merge_msg)
1061 {
1062         struct fmt_merge_msg_opts opts;
1063
1064         memset(&opts, 0, sizeof(opts));
1065         opts.add_title = !have_message;
1066         opts.shortlog_len = shortlog_len;
1067         opts.credit_people = (0 < option_edit);
1068
1069         fmt_merge_msg(merge_names, merge_msg, &opts);
1070         if (merge_msg->len)
1071                 strbuf_setlen(merge_msg, merge_msg->len - 1);
1072 }
1073
1074 static void handle_fetch_head(struct commit_list **remotes, struct strbuf *merge_names)
1075 {
1076         const char *filename;
1077         int fd, pos, npos;
1078         struct strbuf fetch_head_file = STRBUF_INIT;
1079
1080         if (!merge_names)
1081                 merge_names = &fetch_head_file;
1082
1083         filename = git_path_fetch_head();
1084         fd = open(filename, O_RDONLY);
1085         if (fd < 0)
1086                 die_errno(_("could not open '%s' for reading"), filename);
1087
1088         if (strbuf_read(merge_names, fd, 0) < 0)
1089                 die_errno(_("could not read '%s'"), filename);
1090         if (close(fd) < 0)
1091                 die_errno(_("could not close '%s'"), filename);
1092
1093         for (pos = 0; pos < merge_names->len; pos = npos) {
1094                 unsigned char sha1[20];
1095                 char *ptr;
1096                 struct commit *commit;
1097
1098                 ptr = strchr(merge_names->buf + pos, '\n');
1099                 if (ptr)
1100                         npos = ptr - merge_names->buf + 1;
1101                 else
1102                         npos = merge_names->len;
1103
1104                 if (npos - pos < 40 + 2 ||
1105                     get_sha1_hex(merge_names->buf + pos, sha1))
1106                         commit = NULL; /* bad */
1107                 else if (memcmp(merge_names->buf + pos + 40, "\t\t", 2))
1108                         continue; /* not-for-merge */
1109                 else {
1110                         char saved = merge_names->buf[pos + 40];
1111                         merge_names->buf[pos + 40] = '\0';
1112                         commit = get_merge_parent(merge_names->buf + pos);
1113                         merge_names->buf[pos + 40] = saved;
1114                 }
1115                 if (!commit) {
1116                         if (ptr)
1117                                 *ptr = '\0';
1118                         die("not something we can merge in %s: %s",
1119                             filename, merge_names->buf + pos);
1120                 }
1121                 remotes = &commit_list_insert(commit, remotes)->next;
1122         }
1123
1124         if (merge_names == &fetch_head_file)
1125                 strbuf_release(&fetch_head_file);
1126 }
1127
1128 static struct commit_list *collect_parents(struct commit *head_commit,
1129                                            int *head_subsumed,
1130                                            int argc, const char **argv,
1131                                            struct strbuf *merge_msg)
1132 {
1133         int i;
1134         struct commit_list *remoteheads = NULL;
1135         struct commit_list **remotes = &remoteheads;
1136         struct strbuf merge_names = STRBUF_INIT, *autogen = NULL;
1137
1138         if (merge_msg && (!have_message || shortlog_len))
1139                 autogen = &merge_names;
1140
1141         if (head_commit)
1142                 remotes = &commit_list_insert(head_commit, remotes)->next;
1143
1144         if (argc == 1 && !strcmp(argv[0], "FETCH_HEAD")) {
1145                 handle_fetch_head(remotes, autogen);
1146                 remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
1147         } else {
1148                 for (i = 0; i < argc; i++) {
1149                         struct commit *commit = get_merge_parent(argv[i]);
1150                         if (!commit)
1151                                 help_unknown_ref(argv[i], "merge",
1152                                                  "not something we can merge");
1153                         remotes = &commit_list_insert(commit, remotes)->next;
1154                 }
1155                 remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
1156                 if (autogen) {
1157                         struct commit_list *p;
1158                         for (p = remoteheads; p; p = p->next)
1159                                 merge_name(merge_remote_util(p->item)->name, autogen);
1160                 }
1161         }
1162
1163         if (autogen) {
1164                 prepare_merge_message(autogen, merge_msg);
1165                 strbuf_release(autogen);
1166         }
1167
1168         return remoteheads;
1169 }
1170
1171 int cmd_merge(int argc, const char **argv, const char *prefix)
1172 {
1173         unsigned char result_tree[20];
1174         unsigned char stash[20];
1175         unsigned char head_sha1[20];
1176         struct commit *head_commit;
1177         struct strbuf buf = STRBUF_INIT;
1178         const char *head_arg;
1179         int i, ret = 0, head_subsumed;
1180         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
1181         struct commit_list *common = NULL;
1182         const char *best_strategy = NULL, *wt_strategy = NULL;
1183         struct commit_list *remoteheads, *p;
1184         void *branch_to_free;
1185
1186         if (argc == 2 && !strcmp(argv[1], "-h"))
1187                 usage_with_options(builtin_merge_usage, builtin_merge_options);
1188
1189         /*
1190          * Check if we are _not_ on a detached HEAD, i.e. if there is a
1191          * current branch.
1192          */
1193         branch = branch_to_free = resolve_refdup("HEAD", 0, head_sha1, NULL);
1194         if (branch && starts_with(branch, "refs/heads/"))
1195                 branch += 11;
1196         if (!branch || is_null_sha1(head_sha1))
1197                 head_commit = NULL;
1198         else
1199                 head_commit = lookup_commit_or_die(head_sha1, "HEAD");
1200
1201         init_diff_ui_defaults();
1202         git_config(git_merge_config, NULL);
1203
1204         if (branch_mergeoptions)
1205                 parse_branch_merge_options(branch_mergeoptions);
1206         argc = parse_options(argc, argv, prefix, builtin_merge_options,
1207                         builtin_merge_usage, 0);
1208         if (shortlog_len < 0)
1209                 shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;
1210
1211         if (verbosity < 0 && show_progress == -1)
1212                 show_progress = 0;
1213
1214         if (abort_current_merge) {
1215                 int nargc = 2;
1216                 const char *nargv[] = {"reset", "--merge", NULL};
1217
1218                 if (!file_exists(git_path_merge_head()))
1219                         die(_("There is no merge to abort (MERGE_HEAD missing)."));
1220
1221                 /* Invoke 'git reset --merge' */
1222                 ret = cmd_reset(nargc, nargv, prefix);
1223                 goto done;
1224         }
1225
1226         if (read_cache_unmerged())
1227                 die_resolve_conflict("merge");
1228
1229         if (file_exists(git_path_merge_head())) {
1230                 /*
1231                  * There is no unmerged entry, don't advise 'git
1232                  * add/rm <file>', just 'git commit'.
1233                  */
1234                 if (advice_resolve_conflict)
1235                         die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1236                                   "Please, commit your changes before you merge."));
1237                 else
1238                         die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1239         }
1240         if (file_exists(git_path_cherry_pick_head())) {
1241                 if (advice_resolve_conflict)
1242                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1243                             "Please, commit your changes before you merge."));
1244                 else
1245                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
1246         }
1247         resolve_undo_clear();
1248
1249         if (verbosity < 0)
1250                 show_diffstat = 0;
1251
1252         if (squash) {
1253                 if (fast_forward == FF_NO)
1254                         die(_("You cannot combine --squash with --no-ff."));
1255                 option_commit = 0;
1256         }
1257
1258         if (!argc) {
1259                 if (default_to_upstream)
1260                         argc = setup_with_upstream(&argv);
1261                 else
1262                         die(_("No commit specified and merge.defaultToUpstream not set."));
1263         } else if (argc == 1 && !strcmp(argv[0], "-")) {
1264                 argv[0] = "@{-1}";
1265         }
1266
1267         if (!argc)
1268                 usage_with_options(builtin_merge_usage,
1269                         builtin_merge_options);
1270
1271         if (!head_commit) {
1272                 /*
1273                  * If the merged head is a valid one there is no reason
1274                  * to forbid "git merge" into a branch yet to be born.
1275                  * We do the same for "git pull".
1276                  */
1277                 unsigned char *remote_head_sha1;
1278                 if (squash)
1279                         die(_("Squash commit into empty head not supported yet"));
1280                 if (fast_forward == FF_NO)
1281                         die(_("Non-fast-forward commit does not make sense into "
1282                             "an empty head"));
1283                 remoteheads = collect_parents(head_commit, &head_subsumed,
1284                                               argc, argv, NULL);
1285                 if (!remoteheads)
1286                         die(_("%s - not something we can merge"), argv[0]);
1287                 if (remoteheads->next)
1288                         die(_("Can merge only exactly one commit into empty head"));
1289                 remote_head_sha1 = remoteheads->item->object.oid.hash;
1290                 read_empty(remote_head_sha1, 0);
1291                 update_ref("initial pull", "HEAD", remote_head_sha1,
1292                            NULL, 0, UPDATE_REFS_DIE_ON_ERR);
1293                 goto done;
1294         }
1295
1296         /*
1297          * This could be traditional "merge <msg> HEAD <commit>..."  and
1298          * the way we can tell it is to see if the second token is HEAD,
1299          * but some people might have misused the interface and used a
1300          * commit-ish that is the same as HEAD there instead.
1301          * Traditional format never would have "-m" so it is an
1302          * additional safety measure to check for it.
1303          */
1304         if (!have_message &&
1305             is_old_style_invocation(argc, argv, head_commit->object.oid.hash)) {
1306                 warning("old-style 'git merge <msg> HEAD <commit>' is deprecated.");
1307                 strbuf_addstr(&merge_msg, argv[0]);
1308                 head_arg = argv[1];
1309                 argv += 2;
1310                 argc -= 2;
1311                 remoteheads = collect_parents(head_commit, &head_subsumed,
1312                                               argc, argv, NULL);
1313         } else {
1314                 /* We are invoked directly as the first-class UI. */
1315                 head_arg = "HEAD";
1316
1317                 /*
1318                  * All the rest are the commits being merged; prepare
1319                  * the standard merge summary message to be appended
1320                  * to the given message.
1321                  */
1322                 remoteheads = collect_parents(head_commit, &head_subsumed,
1323                                               argc, argv, &merge_msg);
1324         }
1325
1326         if (!head_commit || !argc)
1327                 usage_with_options(builtin_merge_usage,
1328                         builtin_merge_options);
1329
1330         if (verify_signatures) {
1331                 for (p = remoteheads; p; p = p->next) {
1332                         struct commit *commit = p->item;
1333                         char hex[GIT_SHA1_HEXSZ + 1];
1334                         struct signature_check signature_check;
1335                         memset(&signature_check, 0, sizeof(signature_check));
1336
1337                         check_commit_signature(commit, &signature_check);
1338
1339                         find_unique_abbrev_r(hex, commit->object.oid.hash, DEFAULT_ABBREV);
1340                         switch (signature_check.result) {
1341                         case 'G':
1342                                 break;
1343                         case 'U':
1344                                 die(_("Commit %s has an untrusted GPG signature, "
1345                                       "allegedly by %s."), hex, signature_check.signer);
1346                         case 'B':
1347                                 die(_("Commit %s has a bad GPG signature "
1348                                       "allegedly by %s."), hex, signature_check.signer);
1349                         default: /* 'N' */
1350                                 die(_("Commit %s does not have a GPG signature."), hex);
1351                         }
1352                         if (verbosity >= 0 && signature_check.result == 'G')
1353                                 printf(_("Commit %s has a good GPG signature by %s\n"),
1354                                        hex, signature_check.signer);
1355
1356                         signature_check_clear(&signature_check);
1357                 }
1358         }
1359
1360         strbuf_addstr(&buf, "merge");
1361         for (p = remoteheads; p; p = p->next)
1362                 strbuf_addf(&buf, " %s", merge_remote_util(p->item)->name);
1363         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1364         strbuf_reset(&buf);
1365
1366         for (p = remoteheads; p; p = p->next) {
1367                 struct commit *commit = p->item;
1368                 strbuf_addf(&buf, "GITHEAD_%s",
1369                             sha1_to_hex(commit->object.oid.hash));
1370                 setenv(buf.buf, merge_remote_util(commit)->name, 1);
1371                 strbuf_reset(&buf);
1372                 if (fast_forward != FF_ONLY &&
1373                     merge_remote_util(commit) &&
1374                     merge_remote_util(commit)->obj &&
1375                     merge_remote_util(commit)->obj->type == OBJ_TAG)
1376                         fast_forward = FF_NO;
1377         }
1378
1379         if (option_edit < 0)
1380                 option_edit = default_edit_option();
1381
1382         if (!use_strategies) {
1383                 if (!remoteheads)
1384                         ; /* already up-to-date */
1385                 else if (!remoteheads->next)
1386                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1387                 else
1388                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1389         }
1390
1391         for (i = 0; i < use_strategies_nr; i++) {
1392                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
1393                         fast_forward = FF_NO;
1394                 if (use_strategies[i]->attr & NO_TRIVIAL)
1395                         allow_trivial = 0;
1396         }
1397
1398         if (!remoteheads)
1399                 ; /* already up-to-date */
1400         else if (!remoteheads->next)
1401                 common = get_merge_bases(head_commit, remoteheads->item);
1402         else {
1403                 struct commit_list *list = remoteheads;
1404                 commit_list_insert(head_commit, &list);
1405                 common = get_octopus_merge_bases(list);
1406                 free(list);
1407         }
1408
1409         update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.oid.hash,
1410                    NULL, 0, UPDATE_REFS_DIE_ON_ERR);
1411
1412         if (remoteheads && !common) {
1413                 /* No common ancestors found. */
1414                 if (!allow_unrelated_histories)
1415                         die(_("refusing to merge unrelated histories"));
1416                 /* otherwise, we need a real merge. */
1417         } else if (!remoteheads ||
1418                  (!remoteheads->next && !common->next &&
1419                   common->item == remoteheads->item)) {
1420                 /*
1421                  * If head can reach all the merge then we are up to date.
1422                  * but first the most common case of merging one remote.
1423                  */
1424                 finish_up_to_date("Already up-to-date.");
1425                 goto done;
1426         } else if (fast_forward != FF_NO && !remoteheads->next &&
1427                         !common->next &&
1428                         !hashcmp(common->item->object.oid.hash, head_commit->object.oid.hash)) {
1429                 /* Again the most common case of merging one remote. */
1430                 struct strbuf msg = STRBUF_INIT;
1431                 struct commit *commit;
1432
1433                 if (verbosity >= 0) {
1434                         char from[GIT_SHA1_HEXSZ + 1], to[GIT_SHA1_HEXSZ + 1];
1435                         find_unique_abbrev_r(from, head_commit->object.oid.hash,
1436                                               DEFAULT_ABBREV);
1437                         find_unique_abbrev_r(to, remoteheads->item->object.oid.hash,
1438                                               DEFAULT_ABBREV);
1439                         printf(_("Updating %s..%s\n"), from, to);
1440                 }
1441                 strbuf_addstr(&msg, "Fast-forward");
1442                 if (have_message)
1443                         strbuf_addstr(&msg,
1444                                 " (no commit created; -m option ignored)");
1445                 commit = remoteheads->item;
1446                 if (!commit) {
1447                         ret = 1;
1448                         goto done;
1449                 }
1450
1451                 if (checkout_fast_forward(head_commit->object.oid.hash,
1452                                           commit->object.oid.hash,
1453                                           overwrite_ignore)) {
1454                         ret = 1;
1455                         goto done;
1456                 }
1457
1458                 finish(head_commit, remoteheads, commit->object.oid.hash, msg.buf);
1459                 drop_save();
1460                 goto done;
1461         } else if (!remoteheads->next && common->next)
1462                 ;
1463                 /*
1464                  * We are not doing octopus and not fast-forward.  Need
1465                  * a real merge.
1466                  */
1467         else if (!remoteheads->next && !common->next && option_commit) {
1468                 /*
1469                  * We are not doing octopus, not fast-forward, and have
1470                  * only one common.
1471                  */
1472                 refresh_cache(REFRESH_QUIET);
1473                 if (allow_trivial && fast_forward != FF_ONLY) {
1474                         /* See if it is really trivial. */
1475                         git_committer_info(IDENT_STRICT);
1476                         printf(_("Trying really trivial in-index merge...\n"));
1477                         if (!read_tree_trivial(common->item->object.oid.hash,
1478                                                head_commit->object.oid.hash,
1479                                                remoteheads->item->object.oid.hash)) {
1480                                 ret = merge_trivial(head_commit, remoteheads);
1481                                 goto done;
1482                         }
1483                         printf(_("Nope.\n"));
1484                 }
1485         } else {
1486                 /*
1487                  * An octopus.  If we can reach all the remote we are up
1488                  * to date.
1489                  */
1490                 int up_to_date = 1;
1491                 struct commit_list *j;
1492
1493                 for (j = remoteheads; j; j = j->next) {
1494                         struct commit_list *common_one;
1495
1496                         /*
1497                          * Here we *have* to calculate the individual
1498                          * merge_bases again, otherwise "git merge HEAD^
1499                          * HEAD^^" would be missed.
1500                          */
1501                         common_one = get_merge_bases(head_commit, j->item);
1502                         if (hashcmp(common_one->item->object.oid.hash,
1503                                 j->item->object.oid.hash)) {
1504                                 up_to_date = 0;
1505                                 break;
1506                         }
1507                 }
1508                 if (up_to_date) {
1509                         finish_up_to_date("Already up-to-date. Yeeah!");
1510                         goto done;
1511                 }
1512         }
1513
1514         if (fast_forward == FF_ONLY)
1515                 die(_("Not possible to fast-forward, aborting."));
1516
1517         /* We are going to make a new commit. */
1518         git_committer_info(IDENT_STRICT);
1519
1520         /*
1521          * At this point, we need a real merge.  No matter what strategy
1522          * we use, it would operate on the index, possibly affecting the
1523          * working tree, and when resolved cleanly, have the desired
1524          * tree in the index -- this means that the index must be in
1525          * sync with the head commit.  The strategies are responsible
1526          * to ensure this.
1527          */
1528         if (use_strategies_nr == 1 ||
1529             /*
1530              * Stash away the local changes so that we can try more than one.
1531              */
1532             save_state(stash))
1533                 hashcpy(stash, null_sha1);
1534
1535         for (i = 0; i < use_strategies_nr; i++) {
1536                 int ret;
1537                 if (i) {
1538                         printf(_("Rewinding the tree to pristine...\n"));
1539                         restore_state(head_commit->object.oid.hash, stash);
1540                 }
1541                 if (use_strategies_nr != 1)
1542                         printf(_("Trying merge strategy %s...\n"),
1543                                 use_strategies[i]->name);
1544                 /*
1545                  * Remember which strategy left the state in the working
1546                  * tree.
1547                  */
1548                 wt_strategy = use_strategies[i]->name;
1549
1550                 ret = try_merge_strategy(use_strategies[i]->name,
1551                                          common, remoteheads,
1552                                          head_commit, head_arg);
1553                 if (!option_commit && !ret) {
1554                         merge_was_ok = 1;
1555                         /*
1556                          * This is necessary here just to avoid writing
1557                          * the tree, but later we will *not* exit with
1558                          * status code 1 because merge_was_ok is set.
1559                          */
1560                         ret = 1;
1561                 }
1562
1563                 if (ret) {
1564                         /*
1565                          * The backend exits with 1 when conflicts are
1566                          * left to be resolved, with 2 when it does not
1567                          * handle the given merge at all.
1568                          */
1569                         if (ret == 1) {
1570                                 int cnt = evaluate_result();
1571
1572                                 if (best_cnt <= 0 || cnt <= best_cnt) {
1573                                         best_strategy = use_strategies[i]->name;
1574                                         best_cnt = cnt;
1575                                 }
1576                         }
1577                         if (merge_was_ok)
1578                                 break;
1579                         else
1580                                 continue;
1581                 }
1582
1583                 /* Automerge succeeded. */
1584                 write_tree_trivial(result_tree);
1585                 automerge_was_ok = 1;
1586                 break;
1587         }
1588
1589         /*
1590          * If we have a resulting tree, that means the strategy module
1591          * auto resolved the merge cleanly.
1592          */
1593         if (automerge_was_ok) {
1594                 ret = finish_automerge(head_commit, head_subsumed,
1595                                        common, remoteheads,
1596                                        result_tree, wt_strategy);
1597                 goto done;
1598         }
1599
1600         /*
1601          * Pick the result from the best strategy and have the user fix
1602          * it up.
1603          */
1604         if (!best_strategy) {
1605                 restore_state(head_commit->object.oid.hash, stash);
1606                 if (use_strategies_nr > 1)
1607                         fprintf(stderr,
1608                                 _("No merge strategy handled the merge.\n"));
1609                 else
1610                         fprintf(stderr, _("Merge with strategy %s failed.\n"),
1611                                 use_strategies[0]->name);
1612                 ret = 2;
1613                 goto done;
1614         } else if (best_strategy == wt_strategy)
1615                 ; /* We already have its result in the working tree. */
1616         else {
1617                 printf(_("Rewinding the tree to pristine...\n"));
1618                 restore_state(head_commit->object.oid.hash, stash);
1619                 printf(_("Using the %s to prepare resolving by hand.\n"),
1620                         best_strategy);
1621                 try_merge_strategy(best_strategy, common, remoteheads,
1622                                    head_commit, head_arg);
1623         }
1624
1625         if (squash)
1626                 finish(head_commit, remoteheads, NULL, NULL);
1627         else
1628                 write_merge_state(remoteheads);
1629
1630         if (merge_was_ok)
1631                 fprintf(stderr, _("Automatic merge went well; "
1632                         "stopped before committing as requested\n"));
1633         else
1634                 ret = suggest_conflicts();
1635
1636 done:
1637         free(branch_to_free);
1638         return ret;
1639 }