builtin/merge.c

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