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 read_empty(unsigned const char *sha1, int verbose)
 238 {
 239         int i = 0;
 240         const char *args[7];
 241
 242         args[i++] = "read-tree";
 243         if (verbose)
 244                 args[i++] = "-v";
 245         args[i++] = "-m";
 246         args[i++] = "-u";
 247         args[i++] = EMPTY_TREE_SHA1_HEX;
 248         args[i++] = sha1_to_hex(sha1);
 249         args[i] = NULL;
 250
 251         if (run_command_v_opt(args, RUN_GIT_CMD))
 252                 die("read-tree failed");
 253 }
 254
 255 static void reset_hard(unsigned const char *sha1, int verbose)
 256 {
 257         int i = 0;
 258         const char *args[6];
 259
 260         args[i++] = "read-tree";
 261         if (verbose)
 262                 args[i++] = "-v";
 263         args[i++] = "--reset";
 264         args[i++] = "-u";
 265         args[i++] = sha1_to_hex(sha1);
 266         args[i] = NULL;
 267
 268         if (run_command_v_opt(args, RUN_GIT_CMD))
 269                 die("read-tree failed");
 270 }
 271
 272 static void restore_state(void)
 273 {
 274         struct strbuf sb = STRBUF_INIT;
 275         const char *args[] = { "stash", "apply", NULL, NULL };
 276
 277         if (is_null_sha1(stash))
 278                 return;
 279
 280         reset_hard(head, 1);
 281
 282         args[2] = sha1_to_hex(stash);
 283
 284         /*
 285          * It is OK to ignore error here, for example when there was
 286          * nothing to restore.
 287          */
 288         run_command_v_opt(args, RUN_GIT_CMD);
 289
 290         strbuf_release(&sb);
 291         refresh_cache(REFRESH_QUIET);
 292 }
 293
 294 /* This is called when no merge was necessary. */
 295 static void finish_up_to_date(const char *msg)
 296 {
 297         if (verbosity >= 0)
 298                 printf("%s%s\n", squash ? " (nothing to squash)" : "", msg);
 299         drop_save();
 300 }
 301
 302 static void squash_message(void)
 303 {
 304         struct rev_info rev;
 305         struct commit *commit;
 306         struct strbuf out = STRBUF_INIT;
 307         struct commit_list *j;
 308         int fd;
 309         struct pretty_print_context ctx = {0};
 310
 311         printf("Squash commit -- not updating HEAD\n");
 312         fd = open(git_path("SQUASH_MSG"), O_WRONLY | O_CREAT, 0666);
 313         if (fd < 0)
 314                 die_errno("Could not write to '%s'", git_path("SQUASH_MSG"));
 315
 316         init_revisions(&rev, NULL);
 317         rev.ignore_merges = 1;
 318         rev.commit_format = CMIT_FMT_MEDIUM;
 319
 320         commit = lookup_commit(head);
 321         commit->object.flags |= UNINTERESTING;
 322         add_pending_object(&rev, &commit->object, NULL);
 323
 324         for (j = remoteheads; j; j = j->next)
 325                 add_pending_object(&rev, &j->item->object, NULL);
 326
 327         setup_revisions(0, NULL, &rev, NULL);
 328         if (prepare_revision_walk(&rev))
 329                 die("revision walk setup failed");
 330
 331         ctx.abbrev = rev.abbrev;
 332         ctx.date_mode = rev.date_mode;
 333
 334         strbuf_addstr(&out, "Squashed commit of the following:\n");
 335         while ((commit = get_revision(&rev)) != NULL) {
 336                 strbuf_addch(&out, '\n');
 337                 strbuf_addf(&out, "commit %s\n",
 338                         sha1_to_hex(commit->object.sha1));
 339                 pretty_print_commit(rev.commit_format, commit, &out, &ctx);
 340         }
 341         if (write(fd, out.buf, out.len) < 0)
 342                 die_errno("Writing SQUASH_MSG");
 343         if (close(fd))
 344                 die_errno("Finishing SQUASH_MSG");
 345         strbuf_release(&out);
 346 }
 347
 348 static void finish(const unsigned char *new_head, const char *msg)
 349 {
 350         struct strbuf reflog_message = STRBUF_INIT;
 351
 352         if (!msg)
 353                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
 354         else {
 355                 if (verbosity >= 0)
 356                         printf("%s\n", msg);
 357                 strbuf_addf(&reflog_message, "%s: %s",
 358                         getenv("GIT_REFLOG_ACTION"), msg);
 359         }
 360         if (squash) {
 361                 squash_message();
 362         } else {
 363                 if (verbosity >= 0 && !merge_msg.len)
 364                         printf("No merge message -- not updating HEAD\n");
 365                 else {
 366                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 367                         update_ref(reflog_message.buf, "HEAD",
 368                                 new_head, head, 0,
 369                                 DIE_ON_ERR);
 370                         /*
 371                          * We ignore errors in 'gc --auto', since the
 372                          * user should see them.
 373                          */
 374                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 375                 }
 376         }
 377         if (new_head && show_diffstat) {
 378                 struct diff_options opts;
 379                 diff_setup(&opts);
 380                 opts.output_format |=
 381                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 382                 opts.detect_rename = DIFF_DETECT_RENAME;
 383                 if (diff_use_color_default > 0)
 384                         DIFF_OPT_SET(&opts, COLOR_DIFF);
 385                 if (diff_setup_done(&opts) < 0)
 386                         die("diff_setup_done failed");
 387                 diff_tree_sha1(head, new_head, "", &opts);
 388                 diffcore_std(&opts);
 389                 diff_flush(&opts);
 390         }
 391
 392         /* Run a post-merge hook */
 393         run_hook(NULL, "post-merge", squash ? "1" : "0", NULL);
 394
 395         strbuf_release(&reflog_message);
 396 }
 397
 398 /* Get the name for the merge commit's message. */
 399 static void merge_name(const char *remote, struct strbuf *msg)
 400 {
 401         struct object *remote_head;
 402         unsigned char branch_head[20], buf_sha[20];
 403         struct strbuf buf = STRBUF_INIT;
 404         struct strbuf bname = STRBUF_INIT;
 405         const char *ptr;
 406         char *found_ref;
 407         int len, early;
 408
 409         strbuf_branchname(&bname, remote);
 410         remote = bname.buf;
 411
 412         memset(branch_head, 0, sizeof(branch_head));
 413         remote_head = peel_to_type(remote, 0, NULL, OBJ_COMMIT);
 414         if (!remote_head)
 415                 die("'%s' does not point to a commit", remote);
 416
 417         if (dwim_ref(remote, strlen(remote), branch_head, &found_ref) > 0) {
 418                 if (!prefixcmp(found_ref, "refs/heads/")) {
 419                         strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 420                                     sha1_to_hex(branch_head), remote);
 421                         goto cleanup;
 422                 }
 423                 if (!prefixcmp(found_ref, "refs/remotes/")) {
 424                         strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
 425                                     sha1_to_hex(branch_head), remote);
 426                         goto cleanup;
 427                 }
 428         }
 429
 430         /* See if remote matches <name>^^^.. or <name>~<number> */
 431         for (len = 0, ptr = remote + strlen(remote);
 432              remote < ptr && ptr[-1] == '^';
 433              ptr--)
 434                 len++;
 435         if (len)
 436                 early = 1;
 437         else {
 438                 early = 0;
 439                 ptr = strrchr(remote, '~');
 440                 if (ptr) {
 441                         int seen_nonzero = 0;
 442
 443                         len++; /* count ~ */
 444                         while (*++ptr && isdigit(*ptr)) {
 445                                 seen_nonzero |= (*ptr != '0');
 446                                 len++;
 447                         }
 448                         if (*ptr)
 449                                 len = 0; /* not ...~<number> */
 450                         else if (seen_nonzero)
 451                                 early = 1;
 452                         else if (len == 1)
 453                                 early = 1; /* "name~" is "name~1"! */
 454                 }
 455         }
 456         if (len) {
 457                 struct strbuf truname = STRBUF_INIT;
 458                 strbuf_addstr(&truname, "refs/heads/");
 459                 strbuf_addstr(&truname, remote);
 460                 strbuf_setlen(&truname, truname.len - len);
 461                 if (resolve_ref(truname.buf, buf_sha, 1, NULL)) {
 462                         strbuf_addf(msg,
 463                                     "%s\t\tbranch '%s'%s of .\n",
 464                                     sha1_to_hex(remote_head->sha1),
 465                                     truname.buf + 11,
 466                                     (early ? " (early part)" : ""));
 467                         strbuf_release(&truname);
 468                         goto cleanup;
 469                 }
 470         }
 471
 472         if (!strcmp(remote, "FETCH_HEAD") &&
 473                         !access(git_path("FETCH_HEAD"), R_OK)) {
 474                 FILE *fp;
 475                 struct strbuf line = STRBUF_INIT;
 476                 char *ptr;
 477
 478                 fp = fopen(git_path("FETCH_HEAD"), "r");
 479                 if (!fp)
 480                         die_errno("could not open '%s' for reading",
 481                                   git_path("FETCH_HEAD"));
 482                 strbuf_getline(&line, fp, '\n');
 483                 fclose(fp);
 484                 ptr = strstr(line.buf, "\tnot-for-merge\t");
 485                 if (ptr)
 486                         strbuf_remove(&line, ptr-line.buf+1, 13);
 487                 strbuf_addbuf(msg, &line);
 488                 strbuf_release(&line);
 489                 goto cleanup;
 490         }
 491         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 492                 sha1_to_hex(remote_head->sha1), remote);
 493 cleanup:
 494         strbuf_release(&buf);
 495         strbuf_release(&bname);
 496 }
 497
 498 static int git_merge_config(const char *k, const char *v, void *cb)
 499 {
 500         if (branch && !prefixcmp(k, "branch.") &&
 501                 !prefixcmp(k + 7, branch) &&
 502                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
 503                 const char **argv;
 504                 int argc;
 505                 char *buf;
 506
 507                 buf = xstrdup(v);
 508                 argc = split_cmdline(buf, &argv);
 509                 if (argc < 0)
 510                         die("Bad branch.%s.mergeoptions string: %s", branch,
 511                             split_cmdline_strerror(argc));
 512                 argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
 513                 memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
 514                 argc++;
 515                 parse_options(argc, argv, NULL, builtin_merge_options,
 516                               builtin_merge_usage, 0);
 517                 free(buf);
 518         }
 519
 520         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 521                 show_diffstat = git_config_bool(k, v);
 522         else if (!strcmp(k, "pull.twohead"))
 523                 return git_config_string(&pull_twohead, k, v);
 524         else if (!strcmp(k, "pull.octopus"))
 525                 return git_config_string(&pull_octopus, k, v);
 526         else if (!strcmp(k, "merge.renormalize"))
 527                 option_renormalize = git_config_bool(k, v);
 528         else if (!strcmp(k, "merge.log") || !strcmp(k, "merge.summary")) {
 529                 int is_bool;
 530                 shortlog_len = git_config_bool_or_int(k, v, &is_bool);
 531                 if (!is_bool && shortlog_len < 0)
 532                         return error("%s: negative length %s", k, v);
 533                 if (is_bool && shortlog_len)
 534                         shortlog_len = DEFAULT_MERGE_LOG_LEN;
 535                 return 0;
 536         }
 537         return git_diff_ui_config(k, v, cb);
 538 }
 539
 540 static int read_tree_trivial(unsigned char *common, unsigned char *head,
 541                              unsigned char *one)
 542 {
 543         int i, nr_trees = 0;
 544         struct tree *trees[MAX_UNPACK_TREES];
 545         struct tree_desc t[MAX_UNPACK_TREES];
 546         struct unpack_trees_options opts;
 547
 548         memset(&opts, 0, sizeof(opts));
 549         opts.head_idx = 2;
 550         opts.src_index = &the_index;
 551         opts.dst_index = &the_index;
 552         opts.update = 1;
 553         opts.verbose_update = 1;
 554         opts.trivial_merges_only = 1;
 555         opts.merge = 1;
 556         trees[nr_trees] = parse_tree_indirect(common);
 557         if (!trees[nr_trees++])
 558                 return -1;
 559         trees[nr_trees] = parse_tree_indirect(head);
 560         if (!trees[nr_trees++])
 561                 return -1;
 562         trees[nr_trees] = parse_tree_indirect(one);
 563         if (!trees[nr_trees++])
 564                 return -1;
 565         opts.fn = threeway_merge;
 566         cache_tree_free(&active_cache_tree);
 567         for (i = 0; i < nr_trees; i++) {
 568                 parse_tree(trees[i]);
 569                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 570         }
 571         if (unpack_trees(nr_trees, t, &opts))
 572                 return -1;
 573         return 0;
 574 }
 575
 576 static void write_tree_trivial(unsigned char *sha1)
 577 {
 578         if (write_cache_as_tree(sha1, 0, NULL))
 579                 die("git write-tree failed to write a tree");
 580 }
 581
 582 int try_merge_command(const char *strategy, struct commit_list *common,
 583                       const char *head_arg, struct commit_list *remotes)
 584 {
 585         const char **args;
 586         int i = 0, x = 0, ret;
 587         struct commit_list *j;
 588         struct strbuf buf = STRBUF_INIT;
 589
 590         args = xmalloc((4 + xopts_nr + commit_list_count(common) +
 591                         commit_list_count(remotes)) * sizeof(char *));
 592         strbuf_addf(&buf, "merge-%s", strategy);
 593         args[i++] = buf.buf;
 594         for (x = 0; x < xopts_nr; x++) {
 595                 char *s = xmalloc(strlen(xopts[x])+2+1);
 596                 strcpy(s, "--");
 597                 strcpy(s+2, xopts[x]);
 598                 args[i++] = s;
 599         }
 600         for (j = common; j; j = j->next)
 601                 args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
 602         args[i++] = "--";
 603         args[i++] = head_arg;
 604         for (j = remotes; j; j = j->next)
 605                 args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
 606         args[i] = NULL;
 607         ret = run_command_v_opt(args, RUN_GIT_CMD);
 608         strbuf_release(&buf);
 609         i = 1;
 610         for (x = 0; x < xopts_nr; x++)
 611                 free((void *)args[i++]);
 612         for (j = common; j; j = j->next)
 613                 free((void *)args[i++]);
 614         i += 2;
 615         for (j = remotes; j; j = j->next)
 616                 free((void *)args[i++]);
 617         free(args);
 618         discard_cache();
 619         if (read_cache() < 0)
 620                 die("failed to read the cache");
 621         resolve_undo_clear();
 622
 623         return ret;
 624 }
 625
 626 static int try_merge_strategy(const char *strategy, struct commit_list *common,
 627                               const char *head_arg)
 628 {
 629         int index_fd;
 630         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 631
 632         index_fd = hold_locked_index(lock, 1);
 633         refresh_cache(REFRESH_QUIET);
 634         if (active_cache_changed &&
 635                         (write_cache(index_fd, active_cache, active_nr) ||
 636                          commit_locked_index(lock)))
 637                 return error("Unable to write index.");
 638         rollback_lock_file(lock);
 639
 640         if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
 641                 int clean, x;
 642                 struct commit *result;
 643                 struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 644                 int index_fd;
 645                 struct commit_list *reversed = NULL;
 646                 struct merge_options o;
 647                 struct commit_list *j;
 648
 649                 if (remoteheads->next) {
 650                         error("Not handling anything other than two heads merge.");
 651                         return 2;
 652                 }
 653
 654                 init_merge_options(&o);
 655                 if (!strcmp(strategy, "subtree"))
 656                         o.subtree_shift = "";
 657
 658                 o.renormalize = option_renormalize;
 659
 660                 for (x = 0; x < xopts_nr; x++)
 661                         if (parse_merge_opt(&o, xopts[x]))
 662                                 die("Unknown option for merge-recursive: -X%s", xopts[x]);
 663
 664                 o.branch1 = head_arg;
 665                 o.branch2 = remoteheads->item->util;
 666
 667                 for (j = common; j; j = j->next)
 668                         commit_list_insert(j->item, &reversed);
 669
 670                 index_fd = hold_locked_index(lock, 1);
 671                 clean = merge_recursive(&o, lookup_commit(head),
 672                                 remoteheads->item, reversed, &result);
 673                 if (active_cache_changed &&
 674                                 (write_cache(index_fd, active_cache, active_nr) ||
 675                                  commit_locked_index(lock)))
 676                         die ("unable to write %s", get_index_file());
 677                 rollback_lock_file(lock);
 678                 return clean ? 0 : 1;
 679         } else {
 680                 return try_merge_command(strategy, common, head_arg, remoteheads);
 681         }
 682 }
 683
 684 static void count_diff_files(struct diff_queue_struct *q,
 685                              struct diff_options *opt, void *data)
 686 {
 687         int *count = data;
 688
 689         (*count) += q->nr;
 690 }
 691
 692 static int count_unmerged_entries(void)
 693 {
 694         int i, ret = 0;
 695
 696         for (i = 0; i < active_nr; i++)
 697                 if (ce_stage(active_cache[i]))
 698                         ret++;
 699
 700         return ret;
 701 }
 702
 703 int checkout_fast_forward(const unsigned char *head, const unsigned char *remote)
 704 {
 705         struct tree *trees[MAX_UNPACK_TREES];
 706         struct unpack_trees_options opts;
 707         struct tree_desc t[MAX_UNPACK_TREES];
 708         int i, fd, nr_trees = 0;
 709         struct dir_struct dir;
 710         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 711
 712         refresh_cache(REFRESH_QUIET);
 713
 714         fd = hold_locked_index(lock_file, 1);
 715
 716         memset(&trees, 0, sizeof(trees));
 717         memset(&opts, 0, sizeof(opts));
 718         memset(&t, 0, sizeof(t));
 719         memset(&dir, 0, sizeof(dir));
 720         dir.flags |= DIR_SHOW_IGNORED;
 721         dir.exclude_per_dir = ".gitignore";
 722         opts.dir = &dir;
 723
 724         opts.head_idx = 1;
 725         opts.src_index = &the_index;
 726         opts.dst_index = &the_index;
 727         opts.update = 1;
 728         opts.verbose_update = 1;
 729         opts.merge = 1;
 730         opts.fn = twoway_merge;
 731         setup_unpack_trees_porcelain(&opts, "merge");
 732
 733         trees[nr_trees] = parse_tree_indirect(head);
 734         if (!trees[nr_trees++])
 735                 return -1;
 736         trees[nr_trees] = parse_tree_indirect(remote);
 737         if (!trees[nr_trees++])
 738                 return -1;
 739         for (i = 0; i < nr_trees; i++) {
 740                 parse_tree(trees[i]);
 741                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 742         }
 743         if (unpack_trees(nr_trees, t, &opts))
 744                 return -1;
 745         if (write_cache(fd, active_cache, active_nr) ||
 746                 commit_locked_index(lock_file))
 747                 die("unable to write new index file");
 748         return 0;
 749 }
 750
 751 static void split_merge_strategies(const char *string, struct strategy **list,
 752                                    int *nr, int *alloc)
 753 {
 754         char *p, *q, *buf;
 755
 756         if (!string)
 757                 return;
 758
 759         buf = xstrdup(string);
 760         q = buf;
 761         for (;;) {
 762                 p = strchr(q, ' ');
 763                 if (!p) {
 764                         ALLOC_GROW(*list, *nr + 1, *alloc);
 765                         (*list)[(*nr)++].name = xstrdup(q);
 766                         free(buf);
 767                         return;
 768                 } else {
 769                         *p = '\0';
 770                         ALLOC_GROW(*list, *nr + 1, *alloc);
 771                         (*list)[(*nr)++].name = xstrdup(q);
 772                         q = ++p;
 773                 }
 774         }
 775 }
 776
 777 static void add_strategies(const char *string, unsigned attr)
 778 {
 779         struct strategy *list = NULL;
 780         int list_alloc = 0, list_nr = 0, i;
 781
 782         memset(&list, 0, sizeof(list));
 783         split_merge_strategies(string, &list, &list_nr, &list_alloc);
 784         if (list) {
 785                 for (i = 0; i < list_nr; i++)
 786                         append_strategy(get_strategy(list[i].name));
 787                 return;
 788         }
 789         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 790                 if (all_strategy[i].attr & attr)
 791                         append_strategy(&all_strategy[i]);
 792
 793 }
 794
 795 static int merge_trivial(void)
 796 {
 797         unsigned char result_tree[20], result_commit[20];
 798         struct commit_list *parent = xmalloc(sizeof(*parent));
 799
 800         write_tree_trivial(result_tree);
 801         printf("Wonderful.\n");
 802         parent->item = lookup_commit(head);
 803         parent->next = xmalloc(sizeof(*parent->next));
 804         parent->next->item = remoteheads->item;
 805         parent->next->next = NULL;
 806         commit_tree(merge_msg.buf, result_tree, parent, result_commit, NULL);
 807         finish(result_commit, "In-index merge");
 808         drop_save();
 809         return 0;
 810 }
 811
 812 static int finish_automerge(struct commit_list *common,
 813                             unsigned char *result_tree,
 814                             const char *wt_strategy)
 815 {
 816         struct commit_list *parents = NULL, *j;
 817         struct strbuf buf = STRBUF_INIT;
 818         unsigned char result_commit[20];
 819
 820         free_commit_list(common);
 821         if (allow_fast_forward) {
 822                 parents = remoteheads;
 823                 commit_list_insert(lookup_commit(head), &parents);
 824                 parents = reduce_heads(parents);
 825         } else {
 826                 struct commit_list **pptr = &parents;
 827
 828                 pptr = &commit_list_insert(lookup_commit(head),
 829                                 pptr)->next;
 830                 for (j = remoteheads; j; j = j->next)
 831                         pptr = &commit_list_insert(j->item, pptr)->next;
 832         }
 833         free_commit_list(remoteheads);
 834         strbuf_addch(&merge_msg, '\n');
 835         commit_tree(merge_msg.buf, result_tree, parents, result_commit, NULL);
 836         strbuf_addf(&buf, "Merge made by %s.", wt_strategy);
 837         finish(result_commit, buf.buf);
 838         strbuf_release(&buf);
 839         drop_save();
 840         return 0;
 841 }
 842
 843 static int suggest_conflicts(int renormalizing)
 844 {
 845         FILE *fp;
 846         int pos;
 847
 848         fp = fopen(git_path("MERGE_MSG"), "a");
 849         if (!fp)
 850                 die_errno("Could not open '%s' for writing",
 851                           git_path("MERGE_MSG"));
 852         fprintf(fp, "\nConflicts:\n");
 853         for (pos = 0; pos < active_nr; pos++) {
 854                 struct cache_entry *ce = active_cache[pos];
 855
 856                 if (ce_stage(ce)) {
 857                         fprintf(fp, "\t%s\n", ce->name);
 858                         while (pos + 1 < active_nr &&
 859                                         !strcmp(ce->name,
 860                                                 active_cache[pos + 1]->name))
 861                                 pos++;
 862                 }
 863         }
 864         fclose(fp);
 865         rerere(allow_rerere_auto);
 866         printf("Automatic merge failed; "
 867                         "fix conflicts and then commit the result.\n");
 868         return 1;
 869 }
 870
 871 static struct commit *is_old_style_invocation(int argc, const char **argv)
 872 {
 873         struct commit *second_token = NULL;
 874         if (argc > 2) {
 875                 unsigned char second_sha1[20];
 876
 877                 if (get_sha1(argv[1], second_sha1))
 878                         return NULL;
 879                 second_token = lookup_commit_reference_gently(second_sha1, 0);
 880                 if (!second_token)
 881                         die("'%s' is not a commit", argv[1]);
 882                 if (hashcmp(second_token->object.sha1, head))
 883                         return NULL;
 884         }
 885         return second_token;
 886 }
 887
 888 static int evaluate_result(void)
 889 {
 890         int cnt = 0;
 891         struct rev_info rev;
 892
 893         /* Check how many files differ. */
 894         init_revisions(&rev, "");
 895         setup_revisions(0, NULL, &rev, NULL);
 896         rev.diffopt.output_format |=
 897                 DIFF_FORMAT_CALLBACK;
 898         rev.diffopt.format_callback = count_diff_files;
 899         rev.diffopt.format_callback_data = &cnt;
 900         run_diff_files(&rev, 0);
 901
 902         /*
 903          * Check how many unmerged entries are
 904          * there.
 905          */
 906         cnt += count_unmerged_entries();
 907
 908         return cnt;
 909 }
 910
 911 int cmd_merge(int argc, const char **argv, const char *prefix)
 912 {
 913         unsigned char result_tree[20];
 914         struct strbuf buf = STRBUF_INIT;
 915         const char *head_arg;
 916         int flag, head_invalid = 0, i;
 917         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
 918         struct commit_list *common = NULL;
 919         const char *best_strategy = NULL, *wt_strategy = NULL;
 920         struct commit_list **remotes = &remoteheads;
 921
 922         if (read_cache_unmerged()) {
 923                 die_resolve_conflict("merge");
 924         }
 925         if (file_exists(git_path("MERGE_HEAD"))) {
 926                 /*
 927                  * There is no unmerged entry, don't advise 'git
 928                  * add/rm <file>', just 'git commit'.
 929                  */
 930                 if (advice_resolve_conflict)
 931                         die("You have not concluded your merge (MERGE_HEAD exists).\n"
 932                             "Please, commit your changes before you can merge.");
 933                 else
 934                         die("You have not concluded your merge (MERGE_HEAD exists).");
 935         }
 936
 937         resolve_undo_clear();
 938         /*
 939          * Check if we are _not_ on a detached HEAD, i.e. if there is a
 940          * current branch.
 941          */
 942         branch = resolve_ref("HEAD", head, 0, &flag);
 943         if (branch && !prefixcmp(branch, "refs/heads/"))
 944                 branch += 11;
 945         if (is_null_sha1(head))
 946                 head_invalid = 1;
 947
 948         git_config(git_merge_config, NULL);
 949
 950         /* for color.ui */
 951         if (diff_use_color_default == -1)
 952                 diff_use_color_default = git_use_color_default;
 953
 954         argc = parse_options(argc, argv, prefix, builtin_merge_options,
 955                         builtin_merge_usage, 0);
 956         if (verbosity < 0)
 957                 show_diffstat = 0;
 958
 959         if (squash) {
 960                 if (!allow_fast_forward)
 961                         die("You cannot combine --squash with --no-ff.");
 962                 option_commit = 0;
 963         }
 964
 965         if (!allow_fast_forward && fast_forward_only)
 966                 die("You cannot combine --no-ff with --ff-only.");
 967
 968         if (!argc)
 969                 usage_with_options(builtin_merge_usage,
 970                         builtin_merge_options);
 971
 972         /*
 973          * This could be traditional "merge <msg> HEAD <commit>..."  and
 974          * the way we can tell it is to see if the second token is HEAD,
 975          * but some people might have misused the interface and used a
 976          * committish that is the same as HEAD there instead.
 977          * Traditional format never would have "-m" so it is an
 978          * additional safety measure to check for it.
 979          */
 980
 981         if (!have_message && is_old_style_invocation(argc, argv)) {
 982                 strbuf_addstr(&merge_msg, argv[0]);
 983                 head_arg = argv[1];
 984                 argv += 2;
 985                 argc -= 2;
 986         } else if (head_invalid) {
 987                 struct object *remote_head;
 988                 /*
 989                  * If the merged head is a valid one there is no reason
 990                  * to forbid "git merge" into a branch yet to be born.
 991                  * We do the same for "git pull".
 992                  */
 993                 if (argc != 1)
 994                         die("Can merge only exactly one commit into "
 995                                 "empty head");
 996                 if (squash)
 997                         die("Squash commit into empty head not supported yet");
 998                 if (!allow_fast_forward)
 999                         die("Non-fast-forward commit does not make sense into "
1000                             "an empty head");
1001                 remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT);
1002                 if (!remote_head)
1003                         die("%s - not something we can merge", argv[0]);
1004                 update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
1005                                 DIE_ON_ERR);
1006                 read_empty(remote_head->sha1, 0);
1007                 return 0;
1008         } else {
1009                 struct strbuf merge_names = STRBUF_INIT;
1010
1011                 /* We are invoked directly as the first-class UI. */
1012                 head_arg = "HEAD";
1013
1014                 /*
1015                  * All the rest are the commits being merged;
1016                  * prepare the standard merge summary message to
1017                  * be appended to the given message.  If remote
1018                  * is invalid we will die later in the common
1019                  * codepath so we discard the error in this
1020                  * loop.
1021                  */
1022                 for (i = 0; i < argc; i++)
1023                         merge_name(argv[i], &merge_names);
1024
1025                 if (!have_message || shortlog_len) {
1026                         fmt_merge_msg(&merge_names, &merge_msg, !have_message,
1027                                       shortlog_len);
1028                         if (merge_msg.len)
1029                                 strbuf_setlen(&merge_msg, merge_msg.len - 1);
1030                 }
1031         }
1032
1033         if (head_invalid || !argc)
1034                 usage_with_options(builtin_merge_usage,
1035                         builtin_merge_options);
1036
1037         strbuf_addstr(&buf, "merge");
1038         for (i = 0; i < argc; i++)
1039                 strbuf_addf(&buf, " %s", argv[i]);
1040         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1041         strbuf_reset(&buf);
1042
1043         for (i = 0; i < argc; i++) {
1044                 struct object *o;
1045                 struct commit *commit;
1046
1047                 o = peel_to_type(argv[i], 0, NULL, OBJ_COMMIT);
1048                 if (!o)
1049                         die("%s - not something we can merge", argv[i]);
1050                 commit = lookup_commit(o->sha1);
1051                 commit->util = (void *)argv[i];
1052                 remotes = &commit_list_insert(commit, remotes)->next;
1053
1054                 strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
1055                 setenv(buf.buf, argv[i], 1);
1056                 strbuf_reset(&buf);
1057         }
1058
1059         if (!use_strategies) {
1060                 if (!remoteheads->next)
1061                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1062                 else
1063                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1064         }
1065
1066         for (i = 0; i < use_strategies_nr; i++) {
1067                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
1068                         allow_fast_forward = 0;
1069                 if (use_strategies[i]->attr & NO_TRIVIAL)
1070                         allow_trivial = 0;
1071         }
1072
1073         if (!remoteheads->next)
1074                 common = get_merge_bases(lookup_commit(head),
1075                                 remoteheads->item, 1);
1076         else {
1077                 struct commit_list *list = remoteheads;
1078                 commit_list_insert(lookup_commit(head), &list);
1079                 common = get_octopus_merge_bases(list);
1080                 free(list);
1081         }
1082
1083         update_ref("updating ORIG_HEAD", "ORIG_HEAD", head, NULL, 0,
1084                 DIE_ON_ERR);
1085
1086         if (!common)
1087                 ; /* No common ancestors found. We need a real merge. */
1088         else if (!remoteheads->next && !common->next &&
1089                         common->item == remoteheads->item) {
1090                 /*
1091                  * If head can reach all the merge then we are up to date.
1092                  * but first the most common case of merging one remote.
1093                  */
1094                 finish_up_to_date("Already up-to-date.");
1095                 return 0;
1096         } else if (allow_fast_forward && !remoteheads->next &&
1097                         !common->next &&
1098                         !hashcmp(common->item->object.sha1, head)) {
1099                 /* Again the most common case of merging one remote. */
1100                 struct strbuf msg = STRBUF_INIT;
1101                 struct object *o;
1102                 char hex[41];
1103
1104                 strcpy(hex, find_unique_abbrev(head, DEFAULT_ABBREV));
1105
1106                 if (verbosity >= 0)
1107                         printf("Updating %s..%s\n",
1108                                 hex,
1109                                 find_unique_abbrev(remoteheads->item->object.sha1,
1110                                 DEFAULT_ABBREV));
1111                 strbuf_addstr(&msg, "Fast-forward");
1112                 if (have_message)
1113                         strbuf_addstr(&msg,
1114                                 " (no commit created; -m option ignored)");
1115                 o = peel_to_type(sha1_to_hex(remoteheads->item->object.sha1),
1116                         0, NULL, OBJ_COMMIT);
1117                 if (!o)
1118                         return 1;
1119
1120                 if (checkout_fast_forward(head, remoteheads->item->object.sha1))
1121                         return 1;
1122
1123                 finish(o->sha1, msg.buf);
1124                 drop_save();
1125                 return 0;
1126         } else if (!remoteheads->next && common->next)
1127                 ;
1128                 /*
1129                  * We are not doing octopus and not fast-forward.  Need
1130                  * a real merge.
1131                  */
1132         else if (!remoteheads->next && !common->next && option_commit) {
1133                 /*
1134                  * We are not doing octopus, not fast-forward, and have
1135                  * only one common.
1136                  */
1137                 refresh_cache(REFRESH_QUIET);
1138                 if (allow_trivial && !fast_forward_only) {
1139                         /* See if it is really trivial. */
1140                         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1141                         printf("Trying really trivial in-index merge...\n");
1142                         if (!read_tree_trivial(common->item->object.sha1,
1143                                         head, remoteheads->item->object.sha1))
1144                                 return merge_trivial();
1145                         printf("Nope.\n");
1146                 }
1147         } else {
1148                 /*
1149                  * An octopus.  If we can reach all the remote we are up
1150                  * to date.
1151                  */
1152                 int up_to_date = 1;
1153                 struct commit_list *j;
1154
1155                 for (j = remoteheads; j; j = j->next) {
1156                         struct commit_list *common_one;
1157
1158                         /*
1159                          * Here we *have* to calculate the individual
1160                          * merge_bases again, otherwise "git merge HEAD^
1161                          * HEAD^^" would be missed.
1162                          */
1163                         common_one = get_merge_bases(lookup_commit(head),
1164                                 j->item, 1);
1165                         if (hashcmp(common_one->item->object.sha1,
1166                                 j->item->object.sha1)) {
1167                                 up_to_date = 0;
1168                                 break;
1169                         }
1170                 }
1171                 if (up_to_date) {
1172                         finish_up_to_date("Already up-to-date. Yeeah!");
1173                         return 0;
1174                 }
1175         }
1176
1177         if (fast_forward_only)
1178                 die("Not possible to fast-forward, aborting.");
1179
1180         /* We are going to make a new commit. */
1181         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1182
1183         /*
1184          * At this point, we need a real merge.  No matter what strategy
1185          * we use, it would operate on the index, possibly affecting the
1186          * working tree, and when resolved cleanly, have the desired
1187          * tree in the index -- this means that the index must be in
1188          * sync with the head commit.  The strategies are responsible
1189          * to ensure this.
1190          */
1191         if (use_strategies_nr != 1) {
1192                 /*
1193                  * Stash away the local changes so that we can try more
1194                  * than one.
1195                  */
1196                 save_state();
1197         } else {
1198                 memcpy(stash, null_sha1, 20);
1199         }
1200
1201         for (i = 0; i < use_strategies_nr; i++) {
1202                 int ret;
1203                 if (i) {
1204                         printf("Rewinding the tree to pristine...\n");
1205                         restore_state();
1206                 }
1207                 if (use_strategies_nr != 1)
1208                         printf("Trying merge strategy %s...\n",
1209                                 use_strategies[i]->name);
1210                 /*
1211                  * Remember which strategy left the state in the working
1212                  * tree.
1213                  */
1214                 wt_strategy = use_strategies[i]->name;
1215
1216                 ret = try_merge_strategy(use_strategies[i]->name,
1217                         common, head_arg);
1218                 if (!option_commit && !ret) {
1219                         merge_was_ok = 1;
1220                         /*
1221                          * This is necessary here just to avoid writing
1222                          * the tree, but later we will *not* exit with
1223                          * status code 1 because merge_was_ok is set.
1224                          */
1225                         ret = 1;
1226                 }
1227
1228                 if (ret) {
1229                         /*
1230                          * The backend exits with 1 when conflicts are
1231                          * left to be resolved, with 2 when it does not
1232                          * handle the given merge at all.
1233                          */
1234                         if (ret == 1) {
1235                                 int cnt = evaluate_result();
1236
1237                                 if (best_cnt <= 0 || cnt <= best_cnt) {
1238                                         best_strategy = use_strategies[i]->name;
1239                                         best_cnt = cnt;
1240                                 }
1241                         }
1242                         if (merge_was_ok)
1243                                 break;
1244                         else
1245                                 continue;
1246                 }
1247
1248                 /* Automerge succeeded. */
1249                 write_tree_trivial(result_tree);
1250                 automerge_was_ok = 1;
1251                 break;
1252         }
1253
1254         /*
1255          * If we have a resulting tree, that means the strategy module
1256          * auto resolved the merge cleanly.
1257          */
1258         if (automerge_was_ok)
1259                 return finish_automerge(common, result_tree, wt_strategy);
1260
1261         /*
1262          * Pick the result from the best strategy and have the user fix
1263          * it up.
1264          */
1265         if (!best_strategy) {
1266                 restore_state();
1267                 if (use_strategies_nr > 1)
1268                         fprintf(stderr,
1269                                 "No merge strategy handled the merge.\n");
1270                 else
1271                         fprintf(stderr, "Merge with strategy %s failed.\n",
1272                                 use_strategies[0]->name);
1273                 return 2;
1274         } else if (best_strategy == wt_strategy)
1275                 ; /* We already have its result in the working tree. */
1276         else {
1277                 printf("Rewinding the tree to pristine...\n");
1278                 restore_state();
1279                 printf("Using the %s to prepare resolving by hand.\n",
1280                         best_strategy);
1281                 try_merge_strategy(best_strategy, common, head_arg);
1282         }
1283
1284         if (squash)
1285                 finish(NULL, NULL);
1286         else {
1287                 int fd;
1288                 struct commit_list *j;
1289
1290                 for (j = remoteheads; j; j = j->next)
1291                         strbuf_addf(&buf, "%s\n",
1292                                 sha1_to_hex(j->item->object.sha1));
1293                 fd = open(git_path("MERGE_HEAD"), O_WRONLY | O_CREAT, 0666);
1294                 if (fd < 0)
1295                         die_errno("Could not open '%s' for writing",
1296                                   git_path("MERGE_HEAD"));
1297                 if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1298                         die_errno("Could not write to '%s'", git_path("MERGE_HEAD"));
1299                 close(fd);
1300                 strbuf_addch(&merge_msg, '\n');
1301                 fd = open(git_path("MERGE_MSG"), O_WRONLY | O_CREAT, 0666);
1302                 if (fd < 0)
1303                         die_errno("Could not open '%s' for writing",
1304                                   git_path("MERGE_MSG"));
1305                 if (write_in_full(fd, merge_msg.buf, merge_msg.len) !=
1306                         merge_msg.len)
1307                         die_errno("Could not write to '%s'", git_path("MERGE_MSG"));
1308                 close(fd);
1309                 fd = open(git_path("MERGE_MODE"), O_WRONLY | O_CREAT | O_TRUNC, 0666);
1310                 if (fd < 0)
1311                         die_errno("Could not open '%s' for writing",
1312                                   git_path("MERGE_MODE"));
1313                 strbuf_reset(&buf);
1314                 if (!allow_fast_forward)
1315                         strbuf_addf(&buf, "no-ff");
1316                 if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1317                         die_errno("Could not write to '%s'", git_path("MERGE_MODE"));
1318                 close(fd);
1319         }
1320
1321         if (merge_was_ok) {
1322                 fprintf(stderr, "Automatic merge went well; "
1323                         "stopped before committing as requested\n");
1324                 return 0;
1325         } else
1326                 return suggest_conflicts(option_renormalize);
1327 }