Merge branch 'rs/find-pack-entry-bisection' 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 "config.h"
11 #include "parse-options.h"
12 #include "builtin.h"
13 #include "lockfile.h"
14 #include "run-command.h"
15 #include "diff.h"
16 #include "refs.h"
17 #include "commit.h"
18 #include "diffcore.h"
19 #include "revision.h"
20 #include "unpack-trees.h"
21 #include "cache-tree.h"
22 #include "dir.h"
23 #include "utf8.h"
24 #include "log-tree.h"
25 #include "color.h"
26 #include "rerere.h"
27 #include "help.h"
28 #include "merge-recursive.h"
29 #include "resolve-undo.h"
30 #include "remote.h"
31 #include "fmt-merge-msg.h"
32 #include "gpg-interface.h"
33 #include "sequencer.h"
34 #include "string-list.h"
35
36 #define DEFAULT_TWOHEAD (1<<0)
37 #define DEFAULT_OCTOPUS (1<<1)
38 #define NO_FAST_FORWARD (1<<2)
39 #define NO_TRIVIAL      (1<<3)
40
41 struct strategy {
42         const char *name;
43         unsigned attr;
44 };
45
46 static const char * const builtin_merge_usage[] = {
47         N_("git merge [<options>] [<commit>...]"),
48         N_("git merge --abort"),
49         N_("git merge --continue"),
50         NULL
51 };
52
53 static int show_diffstat = 1, shortlog_len = -1, squash;
54 static int option_commit = 1;
55 static int option_edit = -1;
56 static int allow_trivial = 1, have_message, verify_signatures;
57 static int overwrite_ignore = 1;
58 static struct strbuf merge_msg = STRBUF_INIT;
59 static struct strategy **use_strategies;
60 static size_t use_strategies_nr, use_strategies_alloc;
61 static const char **xopts;
62 static size_t xopts_nr, xopts_alloc;
63 static const char *branch;
64 static char *branch_mergeoptions;
65 static int option_renormalize;
66 static int verbosity;
67 static int allow_rerere_auto;
68 static int abort_current_merge;
69 static int continue_current_merge;
70 static int allow_unrelated_histories;
71 static int show_progress = -1;
72 static int default_to_upstream = 1;
73 static const char *sign_commit;
74
75 static struct strategy all_strategy[] = {
76         { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
77         { "octopus",    DEFAULT_OCTOPUS },
78         { "resolve",    0 },
79         { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
80         { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
81 };
82
83 static const char *pull_twohead, *pull_octopus;
84
85 enum ff_type {
86         FF_NO,
87         FF_ALLOW,
88         FF_ONLY
89 };
90
91 static enum ff_type fast_forward = FF_ALLOW;
92
93 static int option_parse_message(const struct option *opt,
94                                 const char *arg, int unset)
95 {
96         struct strbuf *buf = opt->value;
97
98         if (unset)
99                 strbuf_setlen(buf, 0);
100         else if (arg) {
101                 strbuf_addf(buf, "%s%s", buf->len ? "\n\n" : "", arg);
102                 have_message = 1;
103         } else
104                 return error(_("switch `m' requires a value"));
105         return 0;
106 }
107
108 static struct strategy *get_strategy(const char *name)
109 {
110         int i;
111         struct strategy *ret;
112         static struct cmdnames main_cmds, other_cmds;
113         static int loaded;
114
115         if (!name)
116                 return NULL;
117
118         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
119                 if (!strcmp(name, all_strategy[i].name))
120                         return &all_strategy[i];
121
122         if (!loaded) {
123                 struct cmdnames not_strategies;
124                 loaded = 1;
125
126                 memset(&not_strategies, 0, sizeof(struct cmdnames));
127                 load_command_list("git-merge-", &main_cmds, &other_cmds);
128                 for (i = 0; i < main_cmds.cnt; i++) {
129                         int j, found = 0;
130                         struct cmdname *ent = main_cmds.names[i];
131                         for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
132                                 if (!strncmp(ent->name, all_strategy[j].name, ent->len)
133                                                 && !all_strategy[j].name[ent->len])
134                                         found = 1;
135                         if (!found)
136                                 add_cmdname(&not_strategies, ent->name, ent->len);
137                 }
138                 exclude_cmds(&main_cmds, &not_strategies);
139         }
140         if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
141                 fprintf(stderr, _("Could not find merge strategy '%s'.\n"), name);
142                 fprintf(stderr, _("Available strategies are:"));
143                 for (i = 0; i < main_cmds.cnt; i++)
144                         fprintf(stderr, " %s", main_cmds.names[i]->name);
145                 fprintf(stderr, ".\n");
146                 if (other_cmds.cnt) {
147                         fprintf(stderr, _("Available custom strategies are:"));
148                         for (i = 0; i < other_cmds.cnt; i++)
149                                 fprintf(stderr, " %s", other_cmds.names[i]->name);
150                         fprintf(stderr, ".\n");
151                 }
152                 exit(1);
153         }
154
155         ret = xcalloc(1, sizeof(struct strategy));
156         ret->name = xstrdup(name);
157         ret->attr = NO_TRIVIAL;
158         return ret;
159 }
160
161 static void append_strategy(struct strategy *s)
162 {
163         ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
164         use_strategies[use_strategies_nr++] = s;
165 }
166
167 static int option_parse_strategy(const struct option *opt,
168                                  const char *name, int unset)
169 {
170         if (unset)
171                 return 0;
172
173         append_strategy(get_strategy(name));
174         return 0;
175 }
176
177 static int option_parse_x(const struct option *opt,
178                           const char *arg, int unset)
179 {
180         if (unset)
181                 return 0;
182
183         ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
184         xopts[xopts_nr++] = xstrdup(arg);
185         return 0;
186 }
187
188 static int option_parse_n(const struct option *opt,
189                           const char *arg, int unset)
190 {
191         show_diffstat = unset;
192         return 0;
193 }
194
195 static struct option builtin_merge_options[] = {
196         { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
197                 N_("do not show a diffstat at the end of the merge"),
198                 PARSE_OPT_NOARG, option_parse_n },
199         OPT_BOOL(0, "stat", &show_diffstat,
200                 N_("show a diffstat at the end of the merge")),
201         OPT_BOOL(0, "summary", &show_diffstat, N_("(synonym to --stat)")),
202         { OPTION_INTEGER, 0, "log", &shortlog_len, N_("n"),
203           N_("add (at most <n>) entries from shortlog to merge commit message"),
204           PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
205         OPT_BOOL(0, "squash", &squash,
206                 N_("create a single commit instead of doing a merge")),
207         OPT_BOOL(0, "commit", &option_commit,
208                 N_("perform a commit if the merge succeeds (default)")),
209         OPT_BOOL('e', "edit", &option_edit,
210                 N_("edit message before committing")),
211         OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
212         { OPTION_SET_INT, 0, "ff-only", &fast_forward, NULL,
213                 N_("abort if fast-forward is not possible"),
214                 PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, FF_ONLY },
215         OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
216         OPT_BOOL(0, "verify-signatures", &verify_signatures,
217                 N_("verify that the named commit has a valid GPG signature")),
218         OPT_CALLBACK('s', "strategy", &use_strategies, N_("strategy"),
219                 N_("merge strategy to use"), option_parse_strategy),
220         OPT_CALLBACK('X', "strategy-option", &xopts, N_("option=value"),
221                 N_("option for selected merge strategy"), option_parse_x),
222         OPT_CALLBACK('m', "message", &merge_msg, N_("message"),
223                 N_("merge commit message (for a non-fast-forward merge)"),
224                 option_parse_message),
225         OPT__VERBOSITY(&verbosity),
226         OPT_BOOL(0, "abort", &abort_current_merge,
227                 N_("abort the current in-progress merge")),
228         OPT_BOOL(0, "continue", &continue_current_merge,
229                 N_("continue the current in-progress merge")),
230         OPT_BOOL(0, "allow-unrelated-histories", &allow_unrelated_histories,
231                  N_("allow merging unrelated histories")),
232         OPT_SET_INT(0, "progress", &show_progress, N_("force progress reporting"), 1),
233         { OPTION_STRING, 'S', "gpg-sign", &sign_commit, N_("key-id"),
234           N_("GPG sign commit"), PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
235         OPT_BOOL(0, "overwrite-ignore", &overwrite_ignore, N_("update ignored files (default)")),
236         OPT_END()
237 };
238
239 /* Cleans up metadata that is uninteresting after a succeeded merge. */
240 static void drop_save(void)
241 {
242         unlink(git_path_merge_head());
243         unlink(git_path_merge_msg());
244         unlink(git_path_merge_mode());
245 }
246
247 static int save_state(struct object_id *stash)
248 {
249         int len;
250         struct child_process cp = CHILD_PROCESS_INIT;
251         struct strbuf buffer = STRBUF_INIT;
252         const char *argv[] = {"stash", "create", NULL};
253
254         cp.argv = argv;
255         cp.out = -1;
256         cp.git_cmd = 1;
257
258         if (start_command(&cp))
259                 die(_("could not run stash."));
260         len = strbuf_read(&buffer, cp.out, 1024);
261         close(cp.out);
262
263         if (finish_command(&cp) || len < 0)
264                 die(_("stash failed"));
265         else if (!len)          /* no changes */
266                 return -1;
267         strbuf_setlen(&buffer, buffer.len-1);
268         if (get_oid(buffer.buf, stash))
269                 die(_("not a valid object: %s"), buffer.buf);
270         return 0;
271 }
272
273 static void read_empty(unsigned const char *sha1, int verbose)
274 {
275         int i = 0;
276         const char *args[7];
277
278         args[i++] = "read-tree";
279         if (verbose)
280                 args[i++] = "-v";
281         args[i++] = "-m";
282         args[i++] = "-u";
283         args[i++] = EMPTY_TREE_SHA1_HEX;
284         args[i++] = sha1_to_hex(sha1);
285         args[i] = NULL;
286
287         if (run_command_v_opt(args, RUN_GIT_CMD))
288                 die(_("read-tree failed"));
289 }
290
291 static void reset_hard(unsigned const char *sha1, int verbose)
292 {
293         int i = 0;
294         const char *args[6];
295
296         args[i++] = "read-tree";
297         if (verbose)
298                 args[i++] = "-v";
299         args[i++] = "--reset";
300         args[i++] = "-u";
301         args[i++] = sha1_to_hex(sha1);
302         args[i] = NULL;
303
304         if (run_command_v_opt(args, RUN_GIT_CMD))
305                 die(_("read-tree failed"));
306 }
307
308 static void restore_state(const struct object_id *head,
309                           const struct object_id *stash)
310 {
311         struct strbuf sb = STRBUF_INIT;
312         const char *args[] = { "stash", "apply", NULL, NULL };
313
314         if (is_null_oid(stash))
315                 return;
316
317         reset_hard(head->hash, 1);
318
319         args[2] = oid_to_hex(stash);
320
321         /*
322          * It is OK to ignore error here, for example when there was
323          * nothing to restore.
324          */
325         run_command_v_opt(args, RUN_GIT_CMD);
326
327         strbuf_release(&sb);
328         refresh_cache(REFRESH_QUIET);
329 }
330
331 /* This is called when no merge was necessary. */
332 static void finish_up_to_date(const char *msg)
333 {
334         if (verbosity >= 0)
335                 printf("%s%s\n", squash ? _(" (nothing to squash)") : "", msg);
336         drop_save();
337 }
338
339 static void squash_message(struct commit *commit, struct commit_list *remoteheads)
340 {
341         struct rev_info rev;
342         struct strbuf out = STRBUF_INIT;
343         struct commit_list *j;
344         struct pretty_print_context ctx = {0};
345
346         printf(_("Squash commit -- not updating HEAD\n"));
347
348         init_revisions(&rev, NULL);
349         rev.ignore_merges = 1;
350         rev.commit_format = CMIT_FMT_MEDIUM;
351
352         commit->object.flags |= UNINTERESTING;
353         add_pending_object(&rev, &commit->object, NULL);
354
355         for (j = remoteheads; j; j = j->next)
356                 add_pending_object(&rev, &j->item->object, NULL);
357
358         setup_revisions(0, NULL, &rev, NULL);
359         if (prepare_revision_walk(&rev))
360                 die(_("revision walk setup failed"));
361
362         ctx.abbrev = rev.abbrev;
363         ctx.date_mode = rev.date_mode;
364         ctx.fmt = rev.commit_format;
365
366         strbuf_addstr(&out, "Squashed commit of the following:\n");
367         while ((commit = get_revision(&rev)) != NULL) {
368                 strbuf_addch(&out, '\n');
369                 strbuf_addf(&out, "commit %s\n",
370                         oid_to_hex(&commit->object.oid));
371                 pretty_print_commit(&ctx, commit, &out);
372         }
373         write_file_buf(git_path_squash_msg(), out.buf, out.len);
374         strbuf_release(&out);
375 }
376
377 static void finish(struct commit *head_commit,
378                    struct commit_list *remoteheads,
379                    const struct object_id *new_head, const char *msg)
380 {
381         struct strbuf reflog_message = STRBUF_INIT;
382         const struct object_id *head = &head_commit->object.oid;
383
384         if (!msg)
385                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
386         else {
387                 if (verbosity >= 0)
388                         printf("%s\n", msg);
389                 strbuf_addf(&reflog_message, "%s: %s",
390                         getenv("GIT_REFLOG_ACTION"), msg);
391         }
392         if (squash) {
393                 squash_message(head_commit, remoteheads);
394         } else {
395                 if (verbosity >= 0 && !merge_msg.len)
396                         printf(_("No merge message -- not updating HEAD\n"));
397                 else {
398                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
399                         update_ref(reflog_message.buf, "HEAD",
400                                 new_head->hash, head->hash, 0,
401                                 UPDATE_REFS_DIE_ON_ERR);
402                         /*
403                          * We ignore errors in 'gc --auto', since the
404                          * user should see them.
405                          */
406                         close_all_packs();
407                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
408                 }
409         }
410         if (new_head && show_diffstat) {
411                 struct diff_options opts;
412                 diff_setup(&opts);
413                 opts.stat_width = -1; /* use full terminal width */
414                 opts.stat_graph_width = -1; /* respect statGraphWidth config */
415                 opts.output_format |=
416                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
417                 opts.detect_rename = DIFF_DETECT_RENAME;
418                 diff_setup_done(&opts);
419                 diff_tree_oid(head, new_head, "", &opts);
420                 diffcore_std(&opts);
421                 diff_flush(&opts);
422         }
423
424         /* Run a post-merge hook */
425         run_hook_le(NULL, "post-merge", squash ? "1" : "0", NULL);
426
427         strbuf_release(&reflog_message);
428 }
429
430 /* Get the name for the merge commit's message. */
431 static void merge_name(const char *remote, struct strbuf *msg)
432 {
433         struct commit *remote_head;
434         struct object_id branch_head;
435         struct strbuf buf = STRBUF_INIT;
436         struct strbuf bname = STRBUF_INIT;
437         const char *ptr;
438         char *found_ref;
439         int len, early;
440
441         strbuf_branchname(&bname, remote, 0);
442         remote = bname.buf;
443
444         oidclr(&branch_head);
445         remote_head = get_merge_parent(remote);
446         if (!remote_head)
447                 die(_("'%s' does not point to a commit"), remote);
448
449         if (dwim_ref(remote, strlen(remote), branch_head.hash, &found_ref) > 0) {
450                 if (starts_with(found_ref, "refs/heads/")) {
451                         strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
452                                     oid_to_hex(&branch_head), remote);
453                         goto cleanup;
454                 }
455                 if (starts_with(found_ref, "refs/tags/")) {
456                         strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
457                                     oid_to_hex(&branch_head), remote);
458                         goto cleanup;
459                 }
460                 if (starts_with(found_ref, "refs/remotes/")) {
461                         strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
462                                     oid_to_hex(&branch_head), remote);
463                         goto cleanup;
464                 }
465         }
466
467         /* See if remote matches <name>^^^.. or <name>~<number> */
468         for (len = 0, ptr = remote + strlen(remote);
469              remote < ptr && ptr[-1] == '^';
470              ptr--)
471                 len++;
472         if (len)
473                 early = 1;
474         else {
475                 early = 0;
476                 ptr = strrchr(remote, '~');
477                 if (ptr) {
478                         int seen_nonzero = 0;
479
480                         len++; /* count ~ */
481                         while (*++ptr && isdigit(*ptr)) {
482                                 seen_nonzero |= (*ptr != '0');
483                                 len++;
484                         }
485                         if (*ptr)
486                                 len = 0; /* not ...~<number> */
487                         else if (seen_nonzero)
488                                 early = 1;
489                         else if (len == 1)
490                                 early = 1; /* "name~" is "name~1"! */
491                 }
492         }
493         if (len) {
494                 struct strbuf truname = STRBUF_INIT;
495                 strbuf_addf(&truname, "refs/heads/%s", remote);
496                 strbuf_setlen(&truname, truname.len - len);
497                 if (ref_exists(truname.buf)) {
498                         strbuf_addf(msg,
499                                     "%s\t\tbranch '%s'%s of .\n",
500                                     oid_to_hex(&remote_head->object.oid),
501                                     truname.buf + 11,
502                                     (early ? " (early part)" : ""));
503                         strbuf_release(&truname);
504                         goto cleanup;
505                 }
506                 strbuf_release(&truname);
507         }
508
509         if (remote_head->util) {
510                 struct merge_remote_desc *desc;
511                 desc = merge_remote_util(remote_head);
512                 if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
513                         strbuf_addf(msg, "%s\t\t%s '%s'\n",
514                                     oid_to_hex(&desc->obj->oid),
515                                     typename(desc->obj->type),
516                                     remote);
517                         goto cleanup;
518                 }
519         }
520
521         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
522                 oid_to_hex(&remote_head->object.oid), remote);
523 cleanup:
524         strbuf_release(&buf);
525         strbuf_release(&bname);
526 }
527
528 static void parse_branch_merge_options(char *bmo)
529 {
530         const char **argv;
531         int argc;
532
533         if (!bmo)
534                 return;
535         argc = split_cmdline(bmo, &argv);
536         if (argc < 0)
537                 die(_("Bad branch.%s.mergeoptions string: %s"), branch,
538                     split_cmdline_strerror(argc));
539         REALLOC_ARRAY(argv, argc + 2);
540         MOVE_ARRAY(argv + 1, argv, argc + 1);
541         argc++;
542         argv[0] = "branch.*.mergeoptions";
543         parse_options(argc, argv, NULL, builtin_merge_options,
544                       builtin_merge_usage, 0);
545         free(argv);
546 }
547
548 static int git_merge_config(const char *k, const char *v, void *cb)
549 {
550         int status;
551
552         if (branch && starts_with(k, "branch.") &&
553                 starts_with(k + 7, branch) &&
554                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
555                 free(branch_mergeoptions);
556                 branch_mergeoptions = xstrdup(v);
557                 return 0;
558         }
559
560         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
561                 show_diffstat = git_config_bool(k, v);
562         else if (!strcmp(k, "pull.twohead"))
563                 return git_config_string(&pull_twohead, k, v);
564         else if (!strcmp(k, "pull.octopus"))
565                 return git_config_string(&pull_octopus, k, v);
566         else if (!strcmp(k, "merge.renormalize"))
567                 option_renormalize = git_config_bool(k, v);
568         else if (!strcmp(k, "merge.ff")) {
569                 int boolval = git_config_maybe_bool(k, v);
570                 if (0 <= boolval) {
571                         fast_forward = boolval ? FF_ALLOW : FF_NO;
572                 } else if (v && !strcmp(v, "only")) {
573                         fast_forward = FF_ONLY;
574                 } /* do not barf on values from future versions of git */
575                 return 0;
576         } else if (!strcmp(k, "merge.defaulttoupstream")) {
577                 default_to_upstream = git_config_bool(k, v);
578                 return 0;
579         } else if (!strcmp(k, "commit.gpgsign")) {
580                 sign_commit = git_config_bool(k, v) ? "" : NULL;
581                 return 0;
582         }
583
584         status = fmt_merge_msg_config(k, v, cb);
585         if (status)
586                 return status;
587         status = git_gpg_config(k, v, NULL);
588         if (status)
589                 return status;
590         return git_diff_ui_config(k, v, cb);
591 }
592
593 static int read_tree_trivial(struct object_id *common, struct object_id *head,
594                              struct object_id *one)
595 {
596         int i, nr_trees = 0;
597         struct tree *trees[MAX_UNPACK_TREES];
598         struct tree_desc t[MAX_UNPACK_TREES];
599         struct unpack_trees_options opts;
600
601         memset(&opts, 0, sizeof(opts));
602         opts.head_idx = 2;
603         opts.src_index = &the_index;
604         opts.dst_index = &the_index;
605         opts.update = 1;
606         opts.verbose_update = 1;
607         opts.trivial_merges_only = 1;
608         opts.merge = 1;
609         trees[nr_trees] = parse_tree_indirect(common);
610         if (!trees[nr_trees++])
611                 return -1;
612         trees[nr_trees] = parse_tree_indirect(head);
613         if (!trees[nr_trees++])
614                 return -1;
615         trees[nr_trees] = parse_tree_indirect(one);
616         if (!trees[nr_trees++])
617                 return -1;
618         opts.fn = threeway_merge;
619         cache_tree_free(&active_cache_tree);
620         for (i = 0; i < nr_trees; i++) {
621                 parse_tree(trees[i]);
622                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
623         }
624         if (unpack_trees(nr_trees, t, &opts))
625                 return -1;
626         return 0;
627 }
628
629 static void write_tree_trivial(struct object_id *oid)
630 {
631         if (write_cache_as_tree(oid->hash, 0, NULL))
632                 die(_("git write-tree failed to write a tree"));
633 }
634
635 static int try_merge_strategy(const char *strategy, struct commit_list *common,
636                               struct commit_list *remoteheads,
637                               struct commit *head)
638 {
639         static struct lock_file lock;
640         const char *head_arg = "HEAD";
641
642         hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
643         refresh_cache(REFRESH_QUIET);
644         if (active_cache_changed &&
645             write_locked_index(&the_index, &lock, COMMIT_LOCK))
646                 return error(_("Unable to write index."));
647         rollback_lock_file(&lock);
648
649         if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
650                 int clean, x;
651                 struct commit *result;
652                 struct commit_list *reversed = NULL;
653                 struct merge_options o;
654                 struct commit_list *j;
655
656                 if (remoteheads->next) {
657                         error(_("Not handling anything other than two heads merge."));
658                         return 2;
659                 }
660
661                 init_merge_options(&o);
662                 if (!strcmp(strategy, "subtree"))
663                         o.subtree_shift = "";
664
665                 o.renormalize = option_renormalize;
666                 o.show_rename_progress =
667                         show_progress == -1 ? isatty(2) : show_progress;
668
669                 for (x = 0; x < xopts_nr; x++)
670                         if (parse_merge_opt(&o, xopts[x]))
671                                 die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
672
673                 o.branch1 = head_arg;
674                 o.branch2 = merge_remote_util(remoteheads->item)->name;
675
676                 for (j = common; j; j = j->next)
677                         commit_list_insert(j->item, &reversed);
678
679                 hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
680                 clean = merge_recursive(&o, head,
681                                 remoteheads->item, reversed, &result);
682                 if (clean < 0)
683                         exit(128);
684                 if (active_cache_changed &&
685                     write_locked_index(&the_index, &lock, COMMIT_LOCK))
686                         die (_("unable to write %s"), get_index_file());
687                 rollback_lock_file(&lock);
688                 return clean ? 0 : 1;
689         } else {
690                 return try_merge_command(strategy, xopts_nr, xopts,
691                                                 common, head_arg, remoteheads);
692         }
693 }
694
695 static void count_diff_files(struct diff_queue_struct *q,
696                              struct diff_options *opt, void *data)
697 {
698         int *count = data;
699
700         (*count) += q->nr;
701 }
702
703 static int count_unmerged_entries(void)
704 {
705         int i, ret = 0;
706
707         for (i = 0; i < active_nr; i++)
708                 if (ce_stage(active_cache[i]))
709                         ret++;
710
711         return ret;
712 }
713
714 static void add_strategies(const char *string, unsigned attr)
715 {
716         int i;
717
718         if (string) {
719                 struct string_list list = STRING_LIST_INIT_DUP;
720                 struct string_list_item *item;
721                 string_list_split(&list, string, ' ', -1);
722                 for_each_string_list_item(item, &list)
723                         append_strategy(get_strategy(item->string));
724                 string_list_clear(&list, 0);
725                 return;
726         }
727         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
728                 if (all_strategy[i].attr & attr)
729                         append_strategy(&all_strategy[i]);
730
731 }
732
733 static void read_merge_msg(struct strbuf *msg)
734 {
735         const char *filename = git_path_merge_msg();
736         strbuf_reset(msg);
737         if (strbuf_read_file(msg, filename, 0) < 0)
738                 die_errno(_("Could not read from '%s'"), filename);
739 }
740
741 static void write_merge_state(struct commit_list *);
742 static void abort_commit(struct commit_list *remoteheads, const char *err_msg)
743 {
744         if (err_msg)
745                 error("%s", err_msg);
746         fprintf(stderr,
747                 _("Not committing merge; use 'git commit' to complete the merge.\n"));
748         write_merge_state(remoteheads);
749         exit(1);
750 }
751
752 static const char merge_editor_comment[] =
753 N_("Please enter a commit message to explain why this merge is necessary,\n"
754    "especially if it merges an updated upstream into a topic branch.\n"
755    "\n"
756    "Lines starting with '%c' will be ignored, and an empty message aborts\n"
757    "the commit.\n");
758
759 static void write_merge_heads(struct commit_list *);
760 static void prepare_to_commit(struct commit_list *remoteheads)
761 {
762         struct strbuf msg = STRBUF_INIT;
763         strbuf_addbuf(&msg, &merge_msg);
764         strbuf_addch(&msg, '\n');
765         if (squash)
766                 BUG("the control must not reach here under --squash");
767         if (0 < option_edit)
768                 strbuf_commented_addf(&msg, _(merge_editor_comment), comment_line_char);
769         write_merge_heads(remoteheads);
770         write_file_buf(git_path_merge_msg(), msg.buf, msg.len);
771         if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
772                             git_path_merge_msg(), "merge", NULL))
773                 abort_commit(remoteheads, NULL);
774         if (0 < option_edit) {
775                 if (launch_editor(git_path_merge_msg(), NULL, NULL))
776                         abort_commit(remoteheads, NULL);
777         }
778         read_merge_msg(&msg);
779         strbuf_stripspace(&msg, 0 < option_edit);
780         if (!msg.len)
781                 abort_commit(remoteheads, _("Empty commit message."));
782         strbuf_release(&merge_msg);
783         strbuf_addbuf(&merge_msg, &msg);
784         strbuf_release(&msg);
785 }
786
787 static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
788 {
789         struct object_id result_tree, result_commit;
790         struct commit_list *parents, **pptr = &parents;
791         static struct lock_file lock;
792
793         hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
794         refresh_cache(REFRESH_QUIET);
795         if (active_cache_changed &&
796             write_locked_index(&the_index, &lock, COMMIT_LOCK))
797                 return error(_("Unable to write index."));
798         rollback_lock_file(&lock);
799
800         write_tree_trivial(&result_tree);
801         printf(_("Wonderful.\n"));
802         pptr = commit_list_append(head, pptr);
803         pptr = commit_list_append(remoteheads->item, pptr);
804         prepare_to_commit(remoteheads);
805         if (commit_tree(merge_msg.buf, merge_msg.len, result_tree.hash, parents,
806                         result_commit.hash, NULL, sign_commit))
807                 die(_("failed to write commit object"));
808         finish(head, remoteheads, &result_commit, "In-index merge");
809         drop_save();
810         return 0;
811 }
812
813 static int finish_automerge(struct commit *head,
814                             int head_subsumed,
815                             struct commit_list *common,
816                             struct commit_list *remoteheads,
817                             struct object_id *result_tree,
818                             const char *wt_strategy)
819 {
820         struct commit_list *parents = NULL;
821         struct strbuf buf = STRBUF_INIT;
822         struct object_id result_commit;
823
824         free_commit_list(common);
825         parents = remoteheads;
826         if (!head_subsumed || fast_forward == FF_NO)
827                 commit_list_insert(head, &parents);
828         strbuf_addch(&merge_msg, '\n');
829         prepare_to_commit(remoteheads);
830         if (commit_tree(merge_msg.buf, merge_msg.len, result_tree->hash, parents,
831                         result_commit.hash, NULL, sign_commit))
832                 die(_("failed to write commit object"));
833         strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
834         finish(head, remoteheads, &result_commit, buf.buf);
835         strbuf_release(&buf);
836         drop_save();
837         return 0;
838 }
839
840 static int suggest_conflicts(void)
841 {
842         const char *filename;
843         FILE *fp;
844         struct strbuf msgbuf = STRBUF_INIT;
845
846         filename = git_path_merge_msg();
847         fp = xfopen(filename, "a");
848
849         append_conflicts_hint(&msgbuf);
850         fputs(msgbuf.buf, fp);
851         strbuf_release(&msgbuf);
852         fclose(fp);
853         rerere(allow_rerere_auto);
854         printf(_("Automatic merge failed; "
855                         "fix conflicts and then commit the result.\n"));
856         return 1;
857 }
858
859 static int evaluate_result(void)
860 {
861         int cnt = 0;
862         struct rev_info rev;
863
864         /* Check how many files differ. */
865         init_revisions(&rev, "");
866         setup_revisions(0, NULL, &rev, NULL);
867         rev.diffopt.output_format |=
868                 DIFF_FORMAT_CALLBACK;
869         rev.diffopt.format_callback = count_diff_files;
870         rev.diffopt.format_callback_data = &cnt;
871         run_diff_files(&rev, 0);
872
873         /*
874          * Check how many unmerged entries are
875          * there.
876          */
877         cnt += count_unmerged_entries();
878
879         return cnt;
880 }
881
882 /*
883  * Pretend as if the user told us to merge with the remote-tracking
884  * branch we have for the upstream of the current branch
885  */
886 static int setup_with_upstream(const char ***argv)
887 {
888         struct branch *branch = branch_get(NULL);
889         int i;
890         const char **args;
891
892         if (!branch)
893                 die(_("No current branch."));
894         if (!branch->remote_name)
895                 die(_("No remote for the current branch."));
896         if (!branch->merge_nr)
897                 die(_("No default upstream defined for the current branch."));
898
899         args = xcalloc(st_add(branch->merge_nr, 1), sizeof(char *));
900         for (i = 0; i < branch->merge_nr; i++) {
901                 if (!branch->merge[i]->dst)
902                         die(_("No remote-tracking branch for %s from %s"),
903                             branch->merge[i]->src, branch->remote_name);
904                 args[i] = branch->merge[i]->dst;
905         }
906         args[i] = NULL;
907         *argv = args;
908         return i;
909 }
910
911 static void write_merge_heads(struct commit_list *remoteheads)
912 {
913         struct commit_list *j;
914         struct strbuf buf = STRBUF_INIT;
915
916         for (j = remoteheads; j; j = j->next) {
917                 struct object_id *oid;
918                 struct commit *c = j->item;
919                 if (c->util && merge_remote_util(c)->obj) {
920                         oid = &merge_remote_util(c)->obj->oid;
921                 } else {
922                         oid = &c->object.oid;
923                 }
924                 strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
925         }
926         write_file_buf(git_path_merge_head(), buf.buf, buf.len);
927
928         strbuf_reset(&buf);
929         if (fast_forward == FF_NO)
930                 strbuf_addstr(&buf, "no-ff");
931         write_file_buf(git_path_merge_mode(), buf.buf, buf.len);
932 }
933
934 static void write_merge_state(struct commit_list *remoteheads)
935 {
936         write_merge_heads(remoteheads);
937         strbuf_addch(&merge_msg, '\n');
938         write_file_buf(git_path_merge_msg(), merge_msg.buf, merge_msg.len);
939 }
940
941 static int default_edit_option(void)
942 {
943         static const char name[] = "GIT_MERGE_AUTOEDIT";
944         const char *e = getenv(name);
945         struct stat st_stdin, st_stdout;
946
947         if (have_message)
948                 /* an explicit -m msg without --[no-]edit */
949                 return 0;
950
951         if (e) {
952                 int v = git_config_maybe_bool(name, e);
953                 if (v < 0)
954                         die(_("Bad value '%s' in environment '%s'"), e, name);
955                 return v;
956         }
957
958         /* Use editor if stdin and stdout are the same and is a tty */
959         return (!fstat(0, &st_stdin) &&
960                 !fstat(1, &st_stdout) &&
961                 isatty(0) && isatty(1) &&
962                 st_stdin.st_dev == st_stdout.st_dev &&
963                 st_stdin.st_ino == st_stdout.st_ino &&
964                 st_stdin.st_mode == st_stdout.st_mode);
965 }
966
967 static struct commit_list *reduce_parents(struct commit *head_commit,
968                                           int *head_subsumed,
969                                           struct commit_list *remoteheads)
970 {
971         struct commit_list *parents, **remotes;
972
973         /*
974          * Is the current HEAD reachable from another commit being
975          * merged?  If so we do not want to record it as a parent of
976          * the resulting merge, unless --no-ff is given.  We will flip
977          * this variable to 0 when we find HEAD among the independent
978          * tips being merged.
979          */
980         *head_subsumed = 1;
981
982         /* Find what parents to record by checking independent ones. */
983         parents = reduce_heads(remoteheads);
984
985         remoteheads = NULL;
986         remotes = &remoteheads;
987         while (parents) {
988                 struct commit *commit = pop_commit(&parents);
989                 if (commit == head_commit)
990                         *head_subsumed = 0;
991                 else
992                         remotes = &commit_list_insert(commit, remotes)->next;
993         }
994         return remoteheads;
995 }
996
997 static void prepare_merge_message(struct strbuf *merge_names, struct strbuf *merge_msg)
998 {
999         struct fmt_merge_msg_opts opts;
1000
1001         memset(&opts, 0, sizeof(opts));
1002         opts.add_title = !have_message;
1003         opts.shortlog_len = shortlog_len;
1004         opts.credit_people = (0 < option_edit);
1005
1006         fmt_merge_msg(merge_names, merge_msg, &opts);
1007         if (merge_msg->len)
1008                 strbuf_setlen(merge_msg, merge_msg->len - 1);
1009 }
1010
1011 static void handle_fetch_head(struct commit_list **remotes, struct strbuf *merge_names)
1012 {
1013         const char *filename;
1014         int fd, pos, npos;
1015         struct strbuf fetch_head_file = STRBUF_INIT;
1016
1017         if (!merge_names)
1018                 merge_names = &fetch_head_file;
1019
1020         filename = git_path_fetch_head();
1021         fd = open(filename, O_RDONLY);
1022         if (fd < 0)
1023                 die_errno(_("could not open '%s' for reading"), filename);
1024
1025         if (strbuf_read(merge_names, fd, 0) < 0)
1026                 die_errno(_("could not read '%s'"), filename);
1027         if (close(fd) < 0)
1028                 die_errno(_("could not close '%s'"), filename);
1029
1030         for (pos = 0; pos < merge_names->len; pos = npos) {
1031                 struct object_id oid;
1032                 char *ptr;
1033                 struct commit *commit;
1034
1035                 ptr = strchr(merge_names->buf + pos, '\n');
1036                 if (ptr)
1037                         npos = ptr - merge_names->buf + 1;
1038                 else
1039                         npos = merge_names->len;
1040
1041                 if (npos - pos < GIT_SHA1_HEXSZ + 2 ||
1042                     get_oid_hex(merge_names->buf + pos, &oid))
1043                         commit = NULL; /* bad */
1044                 else if (memcmp(merge_names->buf + pos + GIT_SHA1_HEXSZ, "\t\t", 2))
1045                         continue; /* not-for-merge */
1046                 else {
1047                         char saved = merge_names->buf[pos + GIT_SHA1_HEXSZ];
1048                         merge_names->buf[pos + GIT_SHA1_HEXSZ] = '\0';
1049                         commit = get_merge_parent(merge_names->buf + pos);
1050                         merge_names->buf[pos + GIT_SHA1_HEXSZ] = saved;
1051                 }
1052                 if (!commit) {
1053                         if (ptr)
1054                                 *ptr = '\0';
1055                         die(_("not something we can merge in %s: %s"),
1056                             filename, merge_names->buf + pos);
1057                 }
1058                 remotes = &commit_list_insert(commit, remotes)->next;
1059         }
1060
1061         if (merge_names == &fetch_head_file)
1062                 strbuf_release(&fetch_head_file);
1063 }
1064
1065 static struct commit_list *collect_parents(struct commit *head_commit,
1066                                            int *head_subsumed,
1067                                            int argc, const char **argv,
1068                                            struct strbuf *merge_msg)
1069 {
1070         int i;
1071         struct commit_list *remoteheads = NULL;
1072         struct commit_list **remotes = &remoteheads;
1073         struct strbuf merge_names = STRBUF_INIT, *autogen = NULL;
1074
1075         if (merge_msg && (!have_message || shortlog_len))
1076                 autogen = &merge_names;
1077
1078         if (head_commit)
1079                 remotes = &commit_list_insert(head_commit, remotes)->next;
1080
1081         if (argc == 1 && !strcmp(argv[0], "FETCH_HEAD")) {
1082                 handle_fetch_head(remotes, autogen);
1083                 remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
1084         } else {
1085                 for (i = 0; i < argc; i++) {
1086                         struct commit *commit = get_merge_parent(argv[i]);
1087                         if (!commit)
1088                                 help_unknown_ref(argv[i], "merge",
1089                                                  _("not something we can merge"));
1090                         remotes = &commit_list_insert(commit, remotes)->next;
1091                 }
1092                 remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
1093                 if (autogen) {
1094                         struct commit_list *p;
1095                         for (p = remoteheads; p; p = p->next)
1096                                 merge_name(merge_remote_util(p->item)->name, autogen);
1097                 }
1098         }
1099
1100         if (autogen) {
1101                 prepare_merge_message(autogen, merge_msg);
1102                 strbuf_release(autogen);
1103         }
1104
1105         return remoteheads;
1106 }
1107
1108 int cmd_merge(int argc, const char **argv, const char *prefix)
1109 {
1110         struct object_id result_tree, stash, head_oid;
1111         struct commit *head_commit;
1112         struct strbuf buf = STRBUF_INIT;
1113         int i, ret = 0, head_subsumed;
1114         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
1115         struct commit_list *common = NULL;
1116         const char *best_strategy = NULL, *wt_strategy = NULL;
1117         struct commit_list *remoteheads, *p;
1118         void *branch_to_free;
1119         int orig_argc = argc;
1120
1121         if (argc == 2 && !strcmp(argv[1], "-h"))
1122                 usage_with_options(builtin_merge_usage, builtin_merge_options);
1123
1124         /*
1125          * Check if we are _not_ on a detached HEAD, i.e. if there is a
1126          * current branch.
1127          */
1128         branch = branch_to_free = resolve_refdup("HEAD", 0, head_oid.hash, NULL);
1129         if (branch && starts_with(branch, "refs/heads/"))
1130                 branch += 11;
1131         if (!branch || is_null_oid(&head_oid))
1132                 head_commit = NULL;
1133         else
1134                 head_commit = lookup_commit_or_die(&head_oid, "HEAD");
1135
1136         init_diff_ui_defaults();
1137         git_config(git_merge_config, NULL);
1138
1139         if (branch_mergeoptions)
1140                 parse_branch_merge_options(branch_mergeoptions);
1141         argc = parse_options(argc, argv, prefix, builtin_merge_options,
1142                         builtin_merge_usage, 0);
1143         if (shortlog_len < 0)
1144                 shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;
1145
1146         if (verbosity < 0 && show_progress == -1)
1147                 show_progress = 0;
1148
1149         if (abort_current_merge) {
1150                 int nargc = 2;
1151                 const char *nargv[] = {"reset", "--merge", NULL};
1152
1153                 if (orig_argc != 2)
1154                         usage_msg_opt(_("--abort expects no arguments"),
1155                               builtin_merge_usage, builtin_merge_options);
1156
1157                 if (!file_exists(git_path_merge_head()))
1158                         die(_("There is no merge to abort (MERGE_HEAD missing)."));
1159
1160                 /* Invoke 'git reset --merge' */
1161                 ret = cmd_reset(nargc, nargv, prefix);
1162                 goto done;
1163         }
1164
1165         if (continue_current_merge) {
1166                 int nargc = 1;
1167                 const char *nargv[] = {"commit", NULL};
1168
1169                 if (orig_argc != 2)
1170                         usage_msg_opt(_("--continue expects no arguments"),
1171                               builtin_merge_usage, builtin_merge_options);
1172
1173                 if (!file_exists(git_path_merge_head()))
1174                         die(_("There is no merge in progress (MERGE_HEAD missing)."));
1175
1176                 /* Invoke 'git commit' */
1177                 ret = cmd_commit(nargc, nargv, prefix);
1178                 goto done;
1179         }
1180
1181         if (read_cache_unmerged())
1182                 die_resolve_conflict("merge");
1183
1184         if (file_exists(git_path_merge_head())) {
1185                 /*
1186                  * There is no unmerged entry, don't advise 'git
1187                  * add/rm <file>', just 'git commit'.
1188                  */
1189                 if (advice_resolve_conflict)
1190                         die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1191                                   "Please, commit your changes before you merge."));
1192                 else
1193                         die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1194         }
1195         if (file_exists(git_path_cherry_pick_head())) {
1196                 if (advice_resolve_conflict)
1197                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1198                             "Please, commit your changes before you merge."));
1199                 else
1200                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
1201         }
1202         resolve_undo_clear();
1203
1204         if (verbosity < 0)
1205                 show_diffstat = 0;
1206
1207         if (squash) {
1208                 if (fast_forward == FF_NO)
1209                         die(_("You cannot combine --squash with --no-ff."));
1210                 option_commit = 0;
1211         }
1212
1213         if (!argc) {
1214                 if (default_to_upstream)
1215                         argc = setup_with_upstream(&argv);
1216                 else
1217                         die(_("No commit specified and merge.defaultToUpstream not set."));
1218         } else if (argc == 1 && !strcmp(argv[0], "-")) {
1219                 argv[0] = "@{-1}";
1220         }
1221
1222         if (!argc)
1223                 usage_with_options(builtin_merge_usage,
1224                         builtin_merge_options);
1225
1226         if (!head_commit) {
1227                 /*
1228                  * If the merged head is a valid one there is no reason
1229                  * to forbid "git merge" into a branch yet to be born.
1230                  * We do the same for "git pull".
1231                  */
1232                 struct object_id *remote_head_oid;
1233                 if (squash)
1234                         die(_("Squash commit into empty head not supported yet"));
1235                 if (fast_forward == FF_NO)
1236                         die(_("Non-fast-forward commit does not make sense into "
1237                             "an empty head"));
1238                 remoteheads = collect_parents(head_commit, &head_subsumed,
1239                                               argc, argv, NULL);
1240                 if (!remoteheads)
1241                         die(_("%s - not something we can merge"), argv[0]);
1242                 if (remoteheads->next)
1243                         die(_("Can merge only exactly one commit into empty head"));
1244                 remote_head_oid = &remoteheads->item->object.oid;
1245                 read_empty(remote_head_oid->hash, 0);
1246                 update_ref("initial pull", "HEAD", remote_head_oid->hash,
1247                            NULL, 0, UPDATE_REFS_DIE_ON_ERR);
1248                 goto done;
1249         }
1250
1251         /*
1252          * All the rest are the commits being merged; prepare
1253          * the standard merge summary message to be appended
1254          * to the given message.
1255          */
1256         remoteheads = collect_parents(head_commit, &head_subsumed,
1257                                       argc, argv, &merge_msg);
1258
1259         if (!head_commit || !argc)
1260                 usage_with_options(builtin_merge_usage,
1261                         builtin_merge_options);
1262
1263         if (verify_signatures) {
1264                 for (p = remoteheads; p; p = p->next) {
1265                         struct commit *commit = p->item;
1266                         char hex[GIT_MAX_HEXSZ + 1];
1267                         struct signature_check signature_check;
1268                         memset(&signature_check, 0, sizeof(signature_check));
1269
1270                         check_commit_signature(commit, &signature_check);
1271
1272                         find_unique_abbrev_r(hex, commit->object.oid.hash, DEFAULT_ABBREV);
1273                         switch (signature_check.result) {
1274                         case 'G':
1275                                 break;
1276                         case 'U':
1277                                 die(_("Commit %s has an untrusted GPG signature, "
1278                                       "allegedly by %s."), hex, signature_check.signer);
1279                         case 'B':
1280                                 die(_("Commit %s has a bad GPG signature "
1281                                       "allegedly by %s."), hex, signature_check.signer);
1282                         default: /* 'N' */
1283                                 die(_("Commit %s does not have a GPG signature."), hex);
1284                         }
1285                         if (verbosity >= 0 && signature_check.result == 'G')
1286                                 printf(_("Commit %s has a good GPG signature by %s\n"),
1287                                        hex, signature_check.signer);
1288
1289                         signature_check_clear(&signature_check);
1290                 }
1291         }
1292
1293         strbuf_addstr(&buf, "merge");
1294         for (p = remoteheads; p; p = p->next)
1295                 strbuf_addf(&buf, " %s", merge_remote_util(p->item)->name);
1296         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1297         strbuf_reset(&buf);
1298
1299         for (p = remoteheads; p; p = p->next) {
1300                 struct commit *commit = p->item;
1301                 strbuf_addf(&buf, "GITHEAD_%s",
1302                             oid_to_hex(&commit->object.oid));
1303                 setenv(buf.buf, merge_remote_util(commit)->name, 1);
1304                 strbuf_reset(&buf);
1305                 if (fast_forward != FF_ONLY &&
1306                     merge_remote_util(commit) &&
1307                     merge_remote_util(commit)->obj &&
1308                     merge_remote_util(commit)->obj->type == OBJ_TAG)
1309                         fast_forward = FF_NO;
1310         }
1311
1312         if (option_edit < 0)
1313                 option_edit = default_edit_option();
1314
1315         if (!use_strategies) {
1316                 if (!remoteheads)
1317                         ; /* already up-to-date */
1318                 else if (!remoteheads->next)
1319                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1320                 else
1321                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1322         }
1323
1324         for (i = 0; i < use_strategies_nr; i++) {
1325                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
1326                         fast_forward = FF_NO;
1327                 if (use_strategies[i]->attr & NO_TRIVIAL)
1328                         allow_trivial = 0;
1329         }
1330
1331         if (!remoteheads)
1332                 ; /* already up-to-date */
1333         else if (!remoteheads->next)
1334                 common = get_merge_bases(head_commit, remoteheads->item);
1335         else {
1336                 struct commit_list *list = remoteheads;
1337                 commit_list_insert(head_commit, &list);
1338                 common = get_octopus_merge_bases(list);
1339                 free(list);
1340         }
1341
1342         update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.oid.hash,
1343                    NULL, 0, UPDATE_REFS_DIE_ON_ERR);
1344
1345         if (remoteheads && !common) {
1346                 /* No common ancestors found. */
1347                 if (!allow_unrelated_histories)
1348                         die(_("refusing to merge unrelated histories"));
1349                 /* otherwise, we need a real merge. */
1350         } else if (!remoteheads ||
1351                  (!remoteheads->next && !common->next &&
1352                   common->item == remoteheads->item)) {
1353                 /*
1354                  * If head can reach all the merge then we are up to date.
1355                  * but first the most common case of merging one remote.
1356                  */
1357                 finish_up_to_date(_("Already up-to-date."));
1358                 goto done;
1359         } else if (fast_forward != FF_NO && !remoteheads->next &&
1360                         !common->next &&
1361                         !oidcmp(&common->item->object.oid, &head_commit->object.oid)) {
1362                 /* Again the most common case of merging one remote. */
1363                 struct strbuf msg = STRBUF_INIT;
1364                 struct commit *commit;
1365
1366                 if (verbosity >= 0) {
1367                         printf(_("Updating %s..%s\n"),
1368                                find_unique_abbrev(head_commit->object.oid.hash,
1369                                                   DEFAULT_ABBREV),
1370                                find_unique_abbrev(remoteheads->item->object.oid.hash,
1371                                                   DEFAULT_ABBREV));
1372                 }
1373                 strbuf_addstr(&msg, "Fast-forward");
1374                 if (have_message)
1375                         strbuf_addstr(&msg,
1376                                 " (no commit created; -m option ignored)");
1377                 commit = remoteheads->item;
1378                 if (!commit) {
1379                         ret = 1;
1380                         goto done;
1381                 }
1382
1383                 if (checkout_fast_forward(&head_commit->object.oid,
1384                                           &commit->object.oid,
1385                                           overwrite_ignore)) {
1386                         ret = 1;
1387                         goto done;
1388                 }
1389
1390                 finish(head_commit, remoteheads, &commit->object.oid, msg.buf);
1391                 drop_save();
1392                 goto done;
1393         } else if (!remoteheads->next && common->next)
1394                 ;
1395                 /*
1396                  * We are not doing octopus and not fast-forward.  Need
1397                  * a real merge.
1398                  */
1399         else if (!remoteheads->next && !common->next && option_commit) {
1400                 /*
1401                  * We are not doing octopus, not fast-forward, and have
1402                  * only one common.
1403                  */
1404                 refresh_cache(REFRESH_QUIET);
1405                 if (allow_trivial && fast_forward != FF_ONLY) {
1406                         /* See if it is really trivial. */
1407                         git_committer_info(IDENT_STRICT);
1408                         printf(_("Trying really trivial in-index merge...\n"));
1409                         if (!read_tree_trivial(&common->item->object.oid,
1410                                                &head_commit->object.oid,
1411                                                &remoteheads->item->object.oid)) {
1412                                 ret = merge_trivial(head_commit, remoteheads);
1413                                 goto done;
1414                         }
1415                         printf(_("Nope.\n"));
1416                 }
1417         } else {
1418                 /*
1419                  * An octopus.  If we can reach all the remote we are up
1420                  * to date.
1421                  */
1422                 int up_to_date = 1;
1423                 struct commit_list *j;
1424
1425                 for (j = remoteheads; j; j = j->next) {
1426                         struct commit_list *common_one;
1427
1428                         /*
1429                          * Here we *have* to calculate the individual
1430                          * merge_bases again, otherwise "git merge HEAD^
1431                          * HEAD^^" would be missed.
1432                          */
1433                         common_one = get_merge_bases(head_commit, j->item);
1434                         if (oidcmp(&common_one->item->object.oid, &j->item->object.oid)) {
1435                                 up_to_date = 0;
1436                                 break;
1437                         }
1438                 }
1439                 if (up_to_date) {
1440                         finish_up_to_date(_("Already up-to-date. Yeeah!"));
1441                         goto done;
1442                 }
1443         }
1444
1445         if (fast_forward == FF_ONLY)
1446                 die(_("Not possible to fast-forward, aborting."));
1447
1448         /* We are going to make a new commit. */
1449         git_committer_info(IDENT_STRICT);
1450
1451         /*
1452          * At this point, we need a real merge.  No matter what strategy
1453          * we use, it would operate on the index, possibly affecting the
1454          * working tree, and when resolved cleanly, have the desired
1455          * tree in the index -- this means that the index must be in
1456          * sync with the head commit.  The strategies are responsible
1457          * to ensure this.
1458          */
1459         if (use_strategies_nr == 1 ||
1460             /*
1461              * Stash away the local changes so that we can try more than one.
1462              */
1463             save_state(&stash))
1464                 oidclr(&stash);
1465
1466         for (i = 0; i < use_strategies_nr; i++) {
1467                 int ret;
1468                 if (i) {
1469                         printf(_("Rewinding the tree to pristine...\n"));
1470                         restore_state(&head_commit->object.oid, &stash);
1471                 }
1472                 if (use_strategies_nr != 1)
1473                         printf(_("Trying merge strategy %s...\n"),
1474                                 use_strategies[i]->name);
1475                 /*
1476                  * Remember which strategy left the state in the working
1477                  * tree.
1478                  */
1479                 wt_strategy = use_strategies[i]->name;
1480
1481                 ret = try_merge_strategy(use_strategies[i]->name,
1482                                          common, remoteheads,
1483                                          head_commit);
1484                 if (!option_commit && !ret) {
1485                         merge_was_ok = 1;
1486                         /*
1487                          * This is necessary here just to avoid writing
1488                          * the tree, but later we will *not* exit with
1489                          * status code 1 because merge_was_ok is set.
1490                          */
1491                         ret = 1;
1492                 }
1493
1494                 if (ret) {
1495                         /*
1496                          * The backend exits with 1 when conflicts are
1497                          * left to be resolved, with 2 when it does not
1498                          * handle the given merge at all.
1499                          */
1500                         if (ret == 1) {
1501                                 int cnt = evaluate_result();
1502
1503                                 if (best_cnt <= 0 || cnt <= best_cnt) {
1504                                         best_strategy = use_strategies[i]->name;
1505                                         best_cnt = cnt;
1506                                 }
1507                         }
1508                         if (merge_was_ok)
1509                                 break;
1510                         else
1511                                 continue;
1512                 }
1513
1514                 /* Automerge succeeded. */
1515                 write_tree_trivial(&result_tree);
1516                 automerge_was_ok = 1;
1517                 break;
1518         }
1519
1520         /*
1521          * If we have a resulting tree, that means the strategy module
1522          * auto resolved the merge cleanly.
1523          */
1524         if (automerge_was_ok) {
1525                 ret = finish_automerge(head_commit, head_subsumed,
1526                                        common, remoteheads,
1527                                        &result_tree, wt_strategy);
1528                 goto done;
1529         }
1530
1531         /*
1532          * Pick the result from the best strategy and have the user fix
1533          * it up.
1534          */
1535         if (!best_strategy) {
1536                 restore_state(&head_commit->object.oid, &stash);
1537                 if (use_strategies_nr > 1)
1538                         fprintf(stderr,
1539                                 _("No merge strategy handled the merge.\n"));
1540                 else
1541                         fprintf(stderr, _("Merge with strategy %s failed.\n"),
1542                                 use_strategies[0]->name);
1543                 ret = 2;
1544                 goto done;
1545         } else if (best_strategy == wt_strategy)
1546                 ; /* We already have its result in the working tree. */
1547         else {
1548                 printf(_("Rewinding the tree to pristine...\n"));
1549                 restore_state(&head_commit->object.oid, &stash);
1550                 printf(_("Using the %s to prepare resolving by hand.\n"),
1551                         best_strategy);
1552                 try_merge_strategy(best_strategy, common, remoteheads,
1553                                    head_commit);
1554         }
1555
1556         if (squash)
1557                 finish(head_commit, remoteheads, NULL, NULL);
1558         else
1559                 write_merge_state(remoteheads);
1560
1561         if (merge_was_ok)
1562                 fprintf(stderr, _("Automatic merge went well; "
1563                         "stopped before committing as requested\n"));
1564         else
1565                 ret = suggest_conflicts();
1566
1567 done:
1568         free(branch_to_free);
1569         return ret;
1570 }