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