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 #include "remote.h"
  29 #include "fmt-merge-msg.h"
  30
  31 #define DEFAULT_TWOHEAD (1<<0)
  32 #define DEFAULT_OCTOPUS (1<<1)
  33 #define NO_FAST_FORWARD (1<<2)
  34 #define NO_TRIVIAL      (1<<3)
  35
  36 struct strategy {
  37         const char *name;
  38         unsigned attr;
  39 };
  40
  41 static const char * const builtin_merge_usage[] = {
  42         "git merge [options] [<commit>...]",
  43         "git merge [options] <msg> HEAD <commit>",
  44         "git merge --abort",
  45         NULL
  46 };
  47
  48 static int show_diffstat = 1, shortlog_len = -1, squash;
  49 static int option_commit = 1, allow_fast_forward = 1;
  50 static int fast_forward_only, option_edit;
  51 static int allow_trivial = 1, have_message;
  52 static struct strbuf merge_msg;
  53 static struct commit_list *remoteheads;
  54 static struct strategy **use_strategies;
  55 static size_t use_strategies_nr, use_strategies_alloc;
  56 static const char **xopts;
  57 static size_t xopts_nr, xopts_alloc;
  58 static const char *branch;
  59 static char *branch_mergeoptions;
  60 static int option_renormalize;
  61 static int verbosity;
  62 static int allow_rerere_auto;
  63 static int abort_current_merge;
  64 static int show_progress = -1;
  65 static int default_to_upstream;
  66
  67 static struct strategy all_strategy[] = {
  68         { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
  69         { "octopus",    DEFAULT_OCTOPUS },
  70         { "resolve",    0 },
  71         { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
  72         { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
  73 };
  74
  75 static const char *pull_twohead, *pull_octopus;
  76
  77 static int option_parse_message(const struct option *opt,
  78                                 const char *arg, int unset)
  79 {
  80         struct strbuf *buf = opt->value;
  81
  82         if (unset)
  83                 strbuf_setlen(buf, 0);
  84         else if (arg) {
  85                 strbuf_addf(buf, "%s%s", buf->len ? "\n\n" : "", arg);
  86                 have_message = 1;
  87         } else
  88                 return error(_("switch `m' requires a value"));
  89         return 0;
  90 }
  91
  92 static struct strategy *get_strategy(const char *name)
  93 {
  94         int i;
  95         struct strategy *ret;
  96         static struct cmdnames main_cmds, other_cmds;
  97         static int loaded;
  98
  99         if (!name)
 100                 return NULL;
 101
 102         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 103                 if (!strcmp(name, all_strategy[i].name))
 104                         return &all_strategy[i];
 105
 106         if (!loaded) {
 107                 struct cmdnames not_strategies;
 108                 loaded = 1;
 109
 110                 memset(&not_strategies, 0, sizeof(struct cmdnames));
 111                 load_command_list("git-merge-", &main_cmds, &other_cmds);
 112                 for (i = 0; i < main_cmds.cnt; i++) {
 113                         int j, found = 0;
 114                         struct cmdname *ent = main_cmds.names[i];
 115                         for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
 116                                 if (!strncmp(ent->name, all_strategy[j].name, ent->len)
 117                                                 && !all_strategy[j].name[ent->len])
 118                                         found = 1;
 119                         if (!found)
 120                                 add_cmdname(&not_strategies, ent->name, ent->len);
 121                 }
 122                 exclude_cmds(&main_cmds, &not_strategies);
 123         }
 124         if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
 125                 fprintf(stderr, _("Could not find merge strategy '%s'.\n"), name);
 126                 fprintf(stderr, _("Available strategies are:"));
 127                 for (i = 0; i < main_cmds.cnt; i++)
 128                         fprintf(stderr, " %s", main_cmds.names[i]->name);
 129                 fprintf(stderr, ".\n");
 130                 if (other_cmds.cnt) {
 131                         fprintf(stderr, _("Available custom strategies are:"));
 132                         for (i = 0; i < other_cmds.cnt; i++)
 133                                 fprintf(stderr, " %s", other_cmds.names[i]->name);
 134                         fprintf(stderr, ".\n");
 135                 }
 136                 exit(1);
 137         }
 138
 139         ret = xcalloc(1, sizeof(struct strategy));
 140         ret->name = xstrdup(name);
 141         ret->attr = NO_TRIVIAL;
 142         return ret;
 143 }
 144
 145 static void append_strategy(struct strategy *s)
 146 {
 147         ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
 148         use_strategies[use_strategies_nr++] = s;
 149 }
 150
 151 static int option_parse_strategy(const struct option *opt,
 152                                  const char *name, int unset)
 153 {
 154         if (unset)
 155                 return 0;
 156
 157         append_strategy(get_strategy(name));
 158         return 0;
 159 }
 160
 161 static int option_parse_x(const struct option *opt,
 162                           const char *arg, int unset)
 163 {
 164         if (unset)
 165                 return 0;
 166
 167         ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
 168         xopts[xopts_nr++] = xstrdup(arg);
 169         return 0;
 170 }
 171
 172 static int option_parse_n(const struct option *opt,
 173                           const char *arg, int unset)
 174 {
 175         show_diffstat = unset;
 176         return 0;
 177 }
 178
 179 static struct option builtin_merge_options[] = {
 180         { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
 181                 "do not show a diffstat at the end of the merge",
 182                 PARSE_OPT_NOARG, option_parse_n },
 183         OPT_BOOLEAN(0, "stat", &show_diffstat,
 184                 "show a diffstat at the end of the merge"),
 185         OPT_BOOLEAN(0, "summary", &show_diffstat, "(synonym to --stat)"),
 186         { OPTION_INTEGER, 0, "log", &shortlog_len, "n",
 187           "add (at most <n>) entries from shortlog to merge commit message",
 188           PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
 189         OPT_BOOLEAN(0, "squash", &squash,
 190                 "create a single commit instead of doing a merge"),
 191         OPT_BOOLEAN(0, "commit", &option_commit,
 192                 "perform a commit if the merge succeeds (default)"),
 193         OPT_BOOLEAN('e', "edit", &option_edit,
 194                 "edit message before committing"),
 195         OPT_BOOLEAN(0, "ff", &allow_fast_forward,
 196                 "allow fast-forward (default)"),
 197         OPT_BOOLEAN(0, "ff-only", &fast_forward_only,
 198                 "abort if fast-forward is not possible"),
 199         OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
 200         OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
 201                 "merge strategy to use", option_parse_strategy),
 202         OPT_CALLBACK('X', "strategy-option", &xopts, "option=value",
 203                 "option for selected merge strategy", option_parse_x),
 204         OPT_CALLBACK('m', "message", &merge_msg, "message",
 205                 "merge commit message (for a non-fast-forward merge)",
 206                 option_parse_message),
 207         OPT__VERBOSITY(&verbosity),
 208         OPT_BOOLEAN(0, "abort", &abort_current_merge,
 209                 "abort the current in-progress merge"),
 210         OPT_SET_INT(0, "progress", &show_progress, "force progress reporting", 1),
 211         OPT_END()
 212 };
 213
 214 /* Cleans up metadata that is uninteresting after a succeeded merge. */
 215 static void drop_save(void)
 216 {
 217         unlink(git_path("MERGE_HEAD"));
 218         unlink(git_path("MERGE_MSG"));
 219         unlink(git_path("MERGE_MODE"));
 220 }
 221
 222 static int save_state(unsigned char *stash)
 223 {
 224         int len;
 225         struct child_process cp;
 226         struct strbuf buffer = STRBUF_INIT;
 227         const char *argv[] = {"stash", "create", NULL};
 228
 229         memset(&cp, 0, sizeof(cp));
 230         cp.argv = argv;
 231         cp.out = -1;
 232         cp.git_cmd = 1;
 233
 234         if (start_command(&cp))
 235                 die(_("could not run stash."));
 236         len = strbuf_read(&buffer, cp.out, 1024);
 237         close(cp.out);
 238
 239         if (finish_command(&cp) || len < 0)
 240                 die(_("stash failed"));
 241         else if (!len)          /* no changes */
 242                 return -1;
 243         strbuf_setlen(&buffer, buffer.len-1);
 244         if (get_sha1(buffer.buf, stash))
 245                 die(_("not a valid object: %s"), buffer.buf);
 246         return 0;
 247 }
 248
 249 static void read_empty(unsigned const char *sha1, int verbose)
 250 {
 251         int i = 0;
 252         const char *args[7];
 253
 254         args[i++] = "read-tree";
 255         if (verbose)
 256                 args[i++] = "-v";
 257         args[i++] = "-m";
 258         args[i++] = "-u";
 259         args[i++] = EMPTY_TREE_SHA1_HEX;
 260         args[i++] = sha1_to_hex(sha1);
 261         args[i] = NULL;
 262
 263         if (run_command_v_opt(args, RUN_GIT_CMD))
 264                 die(_("read-tree failed"));
 265 }
 266
 267 static void reset_hard(unsigned const char *sha1, int verbose)
 268 {
 269         int i = 0;
 270         const char *args[6];
 271
 272         args[i++] = "read-tree";
 273         if (verbose)
 274                 args[i++] = "-v";
 275         args[i++] = "--reset";
 276         args[i++] = "-u";
 277         args[i++] = sha1_to_hex(sha1);
 278         args[i] = NULL;
 279
 280         if (run_command_v_opt(args, RUN_GIT_CMD))
 281                 die(_("read-tree failed"));
 282 }
 283
 284 static void restore_state(const unsigned char *head,
 285                           const unsigned char *stash)
 286 {
 287         struct strbuf sb = STRBUF_INIT;
 288         const char *args[] = { "stash", "apply", NULL, NULL };
 289
 290         if (is_null_sha1(stash))
 291                 return;
 292
 293         reset_hard(head, 1);
 294
 295         args[2] = sha1_to_hex(stash);
 296
 297         /*
 298          * It is OK to ignore error here, for example when there was
 299          * nothing to restore.
 300          */
 301         run_command_v_opt(args, RUN_GIT_CMD);
 302
 303         strbuf_release(&sb);
 304         refresh_cache(REFRESH_QUIET);
 305 }
 306
 307 /* This is called when no merge was necessary. */
 308 static void finish_up_to_date(const char *msg)
 309 {
 310         if (verbosity >= 0)
 311                 printf("%s%s\n", squash ? _(" (nothing to squash)") : "", msg);
 312         drop_save();
 313 }
 314
 315 static void squash_message(struct commit *commit)
 316 {
 317         struct rev_info rev;
 318         struct strbuf out = STRBUF_INIT;
 319         struct commit_list *j;
 320         const char *filename;
 321         int fd;
 322         struct pretty_print_context ctx = {0};
 323
 324         printf(_("Squash commit -- not updating HEAD\n"));
 325         filename = git_path("SQUASH_MSG");
 326         fd = open(filename, O_WRONLY | O_CREAT, 0666);
 327         if (fd < 0)
 328                 die_errno(_("Could not write to '%s'"), filename);
 329
 330         init_revisions(&rev, NULL);
 331         rev.ignore_merges = 1;
 332         rev.commit_format = CMIT_FMT_MEDIUM;
 333
 334         commit->object.flags |= UNINTERESTING;
 335         add_pending_object(&rev, &commit->object, NULL);
 336
 337         for (j = remoteheads; j; j = j->next)
 338                 add_pending_object(&rev, &j->item->object, NULL);
 339
 340         setup_revisions(0, NULL, &rev, NULL);
 341         if (prepare_revision_walk(&rev))
 342                 die(_("revision walk setup failed"));
 343
 344         ctx.abbrev = rev.abbrev;
 345         ctx.date_mode = rev.date_mode;
 346         ctx.fmt = rev.commit_format;
 347
 348         strbuf_addstr(&out, "Squashed commit of the following:\n");
 349         while ((commit = get_revision(&rev)) != NULL) {
 350                 strbuf_addch(&out, '\n');
 351                 strbuf_addf(&out, "commit %s\n",
 352                         sha1_to_hex(commit->object.sha1));
 353                 pretty_print_commit(&ctx, commit, &out);
 354         }
 355         if (write(fd, out.buf, out.len) < 0)
 356                 die_errno(_("Writing SQUASH_MSG"));
 357         if (close(fd))
 358                 die_errno(_("Finishing SQUASH_MSG"));
 359         strbuf_release(&out);
 360 }
 361
 362 static void finish(struct commit *head_commit,
 363                    const unsigned char *new_head, const char *msg)
 364 {
 365         struct strbuf reflog_message = STRBUF_INIT;
 366         const unsigned char *head = head_commit->object.sha1;
 367
 368         if (!msg)
 369                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
 370         else {
 371                 if (verbosity >= 0)
 372                         printf("%s\n", msg);
 373                 strbuf_addf(&reflog_message, "%s: %s",
 374                         getenv("GIT_REFLOG_ACTION"), msg);
 375         }
 376         if (squash) {
 377                 squash_message(head_commit);
 378         } else {
 379                 if (verbosity >= 0 && !merge_msg.len)
 380                         printf(_("No merge message -- not updating HEAD\n"));
 381                 else {
 382                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 383                         update_ref(reflog_message.buf, "HEAD",
 384                                 new_head, head, 0,
 385                                 DIE_ON_ERR);
 386                         /*
 387                          * We ignore errors in 'gc --auto', since the
 388                          * user should see them.
 389                          */
 390                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 391                 }
 392         }
 393         if (new_head && show_diffstat) {
 394                 struct diff_options opts;
 395                 diff_setup(&opts);
 396                 opts.output_format |=
 397                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 398                 opts.detect_rename = DIFF_DETECT_RENAME;
 399                 if (diff_setup_done(&opts) < 0)
 400                         die(_("diff_setup_done failed"));
 401                 diff_tree_sha1(head, new_head, "", &opts);
 402                 diffcore_std(&opts);
 403                 diff_flush(&opts);
 404         }
 405
 406         /* Run a post-merge hook */
 407         run_hook(NULL, "post-merge", squash ? "1" : "0", NULL);
 408
 409         strbuf_release(&reflog_message);
 410 }
 411
 412 /* Get the name for the merge commit's message. */
 413 static void merge_name(const char *remote, struct strbuf *msg)
 414 {
 415         struct commit *remote_head;
 416         unsigned char branch_head[20], buf_sha[20];
 417         struct strbuf buf = STRBUF_INIT;
 418         struct strbuf bname = STRBUF_INIT;
 419         const char *ptr;
 420         char *found_ref;
 421         int len, early;
 422
 423         strbuf_branchname(&bname, remote);
 424         remote = bname.buf;
 425
 426         memset(branch_head, 0, sizeof(branch_head));
 427         remote_head = get_merge_parent(remote);
 428         if (!remote_head)
 429                 die(_("'%s' does not point to a commit"), remote);
 430
 431         if (dwim_ref(remote, strlen(remote), branch_head, &found_ref) > 0) {
 432                 if (!prefixcmp(found_ref, "refs/heads/")) {
 433                         strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 434                                     sha1_to_hex(branch_head), remote);
 435                         goto cleanup;
 436                 }
 437                 if (!prefixcmp(found_ref, "refs/tags/")) {
 438                         strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
 439                                     sha1_to_hex(branch_head), remote);
 440                         goto cleanup;
 441                 }
 442                 if (!prefixcmp(found_ref, "refs/remotes/")) {
 443                         strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
 444                                     sha1_to_hex(branch_head), remote);
 445                         goto cleanup;
 446                 }
 447         }
 448
 449         /* See if remote matches <name>^^^.. or <name>~<number> */
 450         for (len = 0, ptr = remote + strlen(remote);
 451              remote < ptr && ptr[-1] == '^';
 452              ptr--)
 453                 len++;
 454         if (len)
 455                 early = 1;
 456         else {
 457                 early = 0;
 458                 ptr = strrchr(remote, '~');
 459                 if (ptr) {
 460                         int seen_nonzero = 0;
 461
 462                         len++; /* count ~ */
 463                         while (*++ptr && isdigit(*ptr)) {
 464                                 seen_nonzero |= (*ptr != '0');
 465                                 len++;
 466                         }
 467                         if (*ptr)
 468                                 len = 0; /* not ...~<number> */
 469                         else if (seen_nonzero)
 470                                 early = 1;
 471                         else if (len == 1)
 472                                 early = 1; /* "name~" is "name~1"! */
 473                 }
 474         }
 475         if (len) {
 476                 struct strbuf truname = STRBUF_INIT;
 477                 strbuf_addstr(&truname, "refs/heads/");
 478                 strbuf_addstr(&truname, remote);
 479                 strbuf_setlen(&truname, truname.len - len);
 480                 if (resolve_ref(truname.buf, buf_sha, 1, NULL)) {
 481                         strbuf_addf(msg,
 482                                     "%s\t\tbranch '%s'%s of .\n",
 483                                     sha1_to_hex(remote_head->object.sha1),
 484                                     truname.buf + 11,
 485                                     (early ? " (early part)" : ""));
 486                         strbuf_release(&truname);
 487                         goto cleanup;
 488                 }
 489         }
 490
 491         if (!strcmp(remote, "FETCH_HEAD") &&
 492                         !access(git_path("FETCH_HEAD"), R_OK)) {
 493                 const char *filename;
 494                 FILE *fp;
 495                 struct strbuf line = STRBUF_INIT;
 496                 char *ptr;
 497
 498                 filename = git_path("FETCH_HEAD");
 499                 fp = fopen(filename, "r");
 500                 if (!fp)
 501                         die_errno(_("could not open '%s' for reading"),
 502                                   filename);
 503                 strbuf_getline(&line, fp, '\n');
 504                 fclose(fp);
 505                 ptr = strstr(line.buf, "\tnot-for-merge\t");
 506                 if (ptr)
 507                         strbuf_remove(&line, ptr-line.buf+1, 13);
 508                 strbuf_addbuf(msg, &line);
 509                 strbuf_release(&line);
 510                 goto cleanup;
 511         }
 512         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 513                 sha1_to_hex(remote_head->object.sha1), remote);
 514 cleanup:
 515         strbuf_release(&buf);
 516         strbuf_release(&bname);
 517 }
 518
 519 static void parse_branch_merge_options(char *bmo)
 520 {
 521         const char **argv;
 522         int argc;
 523
 524         if (!bmo)
 525                 return;
 526         argc = split_cmdline(bmo, &argv);
 527         if (argc < 0)
 528                 die(_("Bad branch.%s.mergeoptions string: %s"), branch,
 529                     split_cmdline_strerror(argc));
 530         argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
 531         memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
 532         argc++;
 533         argv[0] = "branch.*.mergeoptions";
 534         parse_options(argc, argv, NULL, builtin_merge_options,
 535                       builtin_merge_usage, 0);
 536         free(argv);
 537 }
 538
 539 static int git_merge_config(const char *k, const char *v, void *cb)
 540 {
 541         int status;
 542
 543         if (branch && !prefixcmp(k, "branch.") &&
 544                 !prefixcmp(k + 7, branch) &&
 545                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
 546                 free(branch_mergeoptions);
 547                 branch_mergeoptions = xstrdup(v);
 548                 return 0;
 549         }
 550
 551         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 552                 show_diffstat = git_config_bool(k, v);
 553         else if (!strcmp(k, "pull.twohead"))
 554                 return git_config_string(&pull_twohead, k, v);
 555         else if (!strcmp(k, "pull.octopus"))
 556                 return git_config_string(&pull_octopus, k, v);
 557         else if (!strcmp(k, "merge.renormalize"))
 558                 option_renormalize = git_config_bool(k, v);
 559         else if (!strcmp(k, "merge.ff")) {
 560                 int boolval = git_config_maybe_bool(k, v);
 561                 if (0 <= boolval) {
 562                         allow_fast_forward = boolval;
 563                 } else if (v && !strcmp(v, "only")) {
 564                         allow_fast_forward = 1;
 565                         fast_forward_only = 1;
 566                 } /* do not barf on values from future versions of git */
 567                 return 0;
 568         } else if (!strcmp(k, "merge.defaulttoupstream")) {
 569                 default_to_upstream = git_config_bool(k, v);
 570                 return 0;
 571         }
 572         status = fmt_merge_msg_config(k, v, cb);
 573         if (status)
 574                 return status;
 575         return git_diff_ui_config(k, v, cb);
 576 }
 577
 578 static int read_tree_trivial(unsigned char *common, unsigned char *head,
 579                              unsigned char *one)
 580 {
 581         int i, nr_trees = 0;
 582         struct tree *trees[MAX_UNPACK_TREES];
 583         struct tree_desc t[MAX_UNPACK_TREES];
 584         struct unpack_trees_options opts;
 585
 586         memset(&opts, 0, sizeof(opts));
 587         opts.head_idx = 2;
 588         opts.src_index = &the_index;
 589         opts.dst_index = &the_index;
 590         opts.update = 1;
 591         opts.verbose_update = 1;
 592         opts.trivial_merges_only = 1;
 593         opts.merge = 1;
 594         trees[nr_trees] = parse_tree_indirect(common);
 595         if (!trees[nr_trees++])
 596                 return -1;
 597         trees[nr_trees] = parse_tree_indirect(head);
 598         if (!trees[nr_trees++])
 599                 return -1;
 600         trees[nr_trees] = parse_tree_indirect(one);
 601         if (!trees[nr_trees++])
 602                 return -1;
 603         opts.fn = threeway_merge;
 604         cache_tree_free(&active_cache_tree);
 605         for (i = 0; i < nr_trees; i++) {
 606                 parse_tree(trees[i]);
 607                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 608         }
 609         if (unpack_trees(nr_trees, t, &opts))
 610                 return -1;
 611         return 0;
 612 }
 613
 614 static void write_tree_trivial(unsigned char *sha1)
 615 {
 616         if (write_cache_as_tree(sha1, 0, NULL))
 617                 die(_("git write-tree failed to write a tree"));
 618 }
 619
 620 static const char *merge_argument(struct commit *commit)
 621 {
 622         if (commit)
 623                 return sha1_to_hex(commit->object.sha1);
 624         else
 625                 return EMPTY_TREE_SHA1_HEX;
 626 }
 627
 628 int try_merge_command(const char *strategy, size_t xopts_nr,
 629                       const char **xopts, struct commit_list *common,
 630                       const char *head_arg, struct commit_list *remotes)
 631 {
 632         const char **args;
 633         int i = 0, x = 0, ret;
 634         struct commit_list *j;
 635         struct strbuf buf = STRBUF_INIT;
 636
 637         args = xmalloc((4 + xopts_nr + commit_list_count(common) +
 638                         commit_list_count(remotes)) * sizeof(char *));
 639         strbuf_addf(&buf, "merge-%s", strategy);
 640         args[i++] = buf.buf;
 641         for (x = 0; x < xopts_nr; x++) {
 642                 char *s = xmalloc(strlen(xopts[x])+2+1);
 643                 strcpy(s, "--");
 644                 strcpy(s+2, xopts[x]);
 645                 args[i++] = s;
 646         }
 647         for (j = common; j; j = j->next)
 648                 args[i++] = xstrdup(merge_argument(j->item));
 649         args[i++] = "--";
 650         args[i++] = head_arg;
 651         for (j = remotes; j; j = j->next)
 652                 args[i++] = xstrdup(merge_argument(j->item));
 653         args[i] = NULL;
 654         ret = run_command_v_opt(args, RUN_GIT_CMD);
 655         strbuf_release(&buf);
 656         i = 1;
 657         for (x = 0; x < xopts_nr; x++)
 658                 free((void *)args[i++]);
 659         for (j = common; j; j = j->next)
 660                 free((void *)args[i++]);
 661         i += 2;
 662         for (j = remotes; j; j = j->next)
 663                 free((void *)args[i++]);
 664         free(args);
 665         discard_cache();
 666         if (read_cache() < 0)
 667                 die(_("failed to read the cache"));
 668         resolve_undo_clear();
 669
 670         return ret;
 671 }
 672
 673 static int try_merge_strategy(const char *strategy, struct commit_list *common,
 674                               struct commit *head, const char *head_arg)
 675 {
 676         int index_fd;
 677         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 678
 679         index_fd = hold_locked_index(lock, 1);
 680         refresh_cache(REFRESH_QUIET);
 681         if (active_cache_changed &&
 682                         (write_cache(index_fd, active_cache, active_nr) ||
 683                          commit_locked_index(lock)))
 684                 return error(_("Unable to write index."));
 685         rollback_lock_file(lock);
 686
 687         if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
 688                 int clean, x;
 689                 struct commit *result;
 690                 struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 691                 int index_fd;
 692                 struct commit_list *reversed = NULL;
 693                 struct merge_options o;
 694                 struct commit_list *j;
 695
 696                 if (remoteheads->next) {
 697                         error(_("Not handling anything other than two heads merge."));
 698                         return 2;
 699                 }
 700
 701                 init_merge_options(&o);
 702                 if (!strcmp(strategy, "subtree"))
 703                         o.subtree_shift = "";
 704
 705                 o.renormalize = option_renormalize;
 706                 o.show_rename_progress =
 707                         show_progress == -1 ? isatty(2) : show_progress;
 708
 709                 for (x = 0; x < xopts_nr; x++)
 710                         if (parse_merge_opt(&o, xopts[x]))
 711                                 die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
 712
 713                 o.branch1 = head_arg;
 714                 o.branch2 = merge_remote_util(remoteheads->item)->name;
 715
 716                 for (j = common; j; j = j->next)
 717                         commit_list_insert(j->item, &reversed);
 718
 719                 index_fd = hold_locked_index(lock, 1);
 720                 clean = merge_recursive(&o, head,
 721                                 remoteheads->item, reversed, &result);
 722                 if (active_cache_changed &&
 723                                 (write_cache(index_fd, active_cache, active_nr) ||
 724                                  commit_locked_index(lock)))
 725                         die (_("unable to write %s"), get_index_file());
 726                 rollback_lock_file(lock);
 727                 return clean ? 0 : 1;
 728         } else {
 729                 return try_merge_command(strategy, xopts_nr, xopts,
 730                                                 common, head_arg, remoteheads);
 731         }
 732 }
 733
 734 static void count_diff_files(struct diff_queue_struct *q,
 735                              struct diff_options *opt, void *data)
 736 {
 737         int *count = data;
 738
 739         (*count) += q->nr;
 740 }
 741
 742 static int count_unmerged_entries(void)
 743 {
 744         int i, ret = 0;
 745
 746         for (i = 0; i < active_nr; i++)
 747                 if (ce_stage(active_cache[i]))
 748                         ret++;
 749
 750         return ret;
 751 }
 752
 753 int checkout_fast_forward(const unsigned char *head, const unsigned char *remote)
 754 {
 755         struct tree *trees[MAX_UNPACK_TREES];
 756         struct unpack_trees_options opts;
 757         struct tree_desc t[MAX_UNPACK_TREES];
 758         int i, fd, nr_trees = 0;
 759         struct dir_struct dir;
 760         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 761
 762         refresh_cache(REFRESH_QUIET);
 763
 764         fd = hold_locked_index(lock_file, 1);
 765
 766         memset(&trees, 0, sizeof(trees));
 767         memset(&opts, 0, sizeof(opts));
 768         memset(&t, 0, sizeof(t));
 769         memset(&dir, 0, sizeof(dir));
 770         dir.flags |= DIR_SHOW_IGNORED;
 771         setup_standard_excludes(&dir);
 772         opts.dir = &dir;
 773
 774         opts.head_idx = 1;
 775         opts.src_index = &the_index;
 776         opts.dst_index = &the_index;
 777         opts.update = 1;
 778         opts.verbose_update = 1;
 779         opts.merge = 1;
 780         opts.fn = twoway_merge;
 781         setup_unpack_trees_porcelain(&opts, "merge");
 782
 783         trees[nr_trees] = parse_tree_indirect(head);
 784         if (!trees[nr_trees++])
 785                 return -1;
 786         trees[nr_trees] = parse_tree_indirect(remote);
 787         if (!trees[nr_trees++])
 788                 return -1;
 789         for (i = 0; i < nr_trees; i++) {
 790                 parse_tree(trees[i]);
 791                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 792         }
 793         if (unpack_trees(nr_trees, t, &opts))
 794                 return -1;
 795         if (write_cache(fd, active_cache, active_nr) ||
 796                 commit_locked_index(lock_file))
 797                 die(_("unable to write new index file"));
 798         return 0;
 799 }
 800
 801 static void split_merge_strategies(const char *string, struct strategy **list,
 802                                    int *nr, int *alloc)
 803 {
 804         char *p, *q, *buf;
 805
 806         if (!string)
 807                 return;
 808
 809         buf = xstrdup(string);
 810         q = buf;
 811         for (;;) {
 812                 p = strchr(q, ' ');
 813                 if (!p) {
 814                         ALLOC_GROW(*list, *nr + 1, *alloc);
 815                         (*list)[(*nr)++].name = xstrdup(q);
 816                         free(buf);
 817                         return;
 818                 } else {
 819                         *p = '\0';
 820                         ALLOC_GROW(*list, *nr + 1, *alloc);
 821                         (*list)[(*nr)++].name = xstrdup(q);
 822                         q = ++p;
 823                 }
 824         }
 825 }
 826
 827 static void add_strategies(const char *string, unsigned attr)
 828 {
 829         struct strategy *list = NULL;
 830         int list_alloc = 0, list_nr = 0, i;
 831
 832         memset(&list, 0, sizeof(list));
 833         split_merge_strategies(string, &list, &list_nr, &list_alloc);
 834         if (list) {
 835                 for (i = 0; i < list_nr; i++)
 836                         append_strategy(get_strategy(list[i].name));
 837                 return;
 838         }
 839         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 840                 if (all_strategy[i].attr & attr)
 841                         append_strategy(&all_strategy[i]);
 842
 843 }
 844
 845 static void write_merge_msg(struct strbuf *msg)
 846 {
 847         const char *filename = git_path("MERGE_MSG");
 848         int fd = open(filename, O_WRONLY | O_CREAT, 0666);
 849         if (fd < 0)
 850                 die_errno(_("Could not open '%s' for writing"),
 851                           filename);
 852         if (write_in_full(fd, msg->buf, msg->len) != msg->len)
 853                 die_errno(_("Could not write to '%s'"), filename);
 854         close(fd);
 855 }
 856
 857 static void read_merge_msg(struct strbuf *msg)
 858 {
 859         const char *filename = git_path("MERGE_MSG");
 860         strbuf_reset(msg);
 861         if (strbuf_read_file(msg, filename, 0) < 0)
 862                 die_errno(_("Could not read from '%s'"), filename);
 863 }
 864
 865 static void write_merge_state(void);
 866 static void abort_commit(const char *err_msg)
 867 {
 868         if (err_msg)
 869                 error("%s", err_msg);
 870         fprintf(stderr,
 871                 _("Not committing merge; use 'git commit' to complete the merge.\n"));
 872         write_merge_state();
 873         exit(1);
 874 }
 875
 876 static void prepare_to_commit(void)
 877 {
 878         struct strbuf msg = STRBUF_INIT;
 879         strbuf_addbuf(&msg, &merge_msg);
 880         strbuf_addch(&msg, '\n');
 881         write_merge_msg(&msg);
 882         run_hook(get_index_file(), "prepare-commit-msg",
 883                  git_path("MERGE_MSG"), "merge", NULL, NULL);
 884         if (option_edit) {
 885                 if (launch_editor(git_path("MERGE_MSG"), NULL, NULL))
 886                         abort_commit(NULL);
 887         }
 888         read_merge_msg(&msg);
 889         stripspace(&msg, option_edit);
 890         if (!msg.len)
 891                 abort_commit(_("Empty commit message."));
 892         strbuf_release(&merge_msg);
 893         strbuf_addbuf(&merge_msg, &msg);
 894         strbuf_release(&msg);
 895 }
 896
 897 static int merge_trivial(struct commit *head)
 898 {
 899         unsigned char result_tree[20], result_commit[20];
 900         struct commit_list *parent = xmalloc(sizeof(*parent));
 901
 902         write_tree_trivial(result_tree);
 903         printf(_("Wonderful.\n"));
 904         parent->item = head;
 905         parent->next = xmalloc(sizeof(*parent->next));
 906         parent->next->item = remoteheads->item;
 907         parent->next->next = NULL;
 908         prepare_to_commit();
 909         commit_tree(merge_msg.buf, result_tree, parent, result_commit, NULL);
 910         finish(head, result_commit, "In-index merge");
 911         drop_save();
 912         return 0;
 913 }
 914
 915 static int finish_automerge(struct commit *head,
 916                             struct commit_list *common,
 917                             unsigned char *result_tree,
 918                             const char *wt_strategy)
 919 {
 920         struct commit_list *parents = NULL, *j;
 921         struct strbuf buf = STRBUF_INIT;
 922         unsigned char result_commit[20];
 923
 924         free_commit_list(common);
 925         if (allow_fast_forward) {
 926                 parents = remoteheads;
 927                 commit_list_insert(head, &parents);
 928                 parents = reduce_heads(parents);
 929         } else {
 930                 struct commit_list **pptr = &parents;
 931
 932                 pptr = &commit_list_insert(head,
 933                                 pptr)->next;
 934                 for (j = remoteheads; j; j = j->next)
 935                         pptr = &commit_list_insert(j->item, pptr)->next;
 936         }
 937         strbuf_addch(&merge_msg, '\n');
 938         prepare_to_commit();
 939         free_commit_list(remoteheads);
 940         commit_tree(merge_msg.buf, result_tree, parents, result_commit, NULL);
 941         strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
 942         finish(head, result_commit, buf.buf);
 943         strbuf_release(&buf);
 944         drop_save();
 945         return 0;
 946 }
 947
 948 static int suggest_conflicts(int renormalizing)
 949 {
 950         const char *filename;
 951         FILE *fp;
 952         int pos;
 953
 954         filename = git_path("MERGE_MSG");
 955         fp = fopen(filename, "a");
 956         if (!fp)
 957                 die_errno(_("Could not open '%s' for writing"), filename);
 958         fprintf(fp, "\nConflicts:\n");
 959         for (pos = 0; pos < active_nr; pos++) {
 960                 struct cache_entry *ce = active_cache[pos];
 961
 962                 if (ce_stage(ce)) {
 963                         fprintf(fp, "\t%s\n", ce->name);
 964                         while (pos + 1 < active_nr &&
 965                                         !strcmp(ce->name,
 966                                                 active_cache[pos + 1]->name))
 967                                 pos++;
 968                 }
 969         }
 970         fclose(fp);
 971         rerere(allow_rerere_auto);
 972         printf(_("Automatic merge failed; "
 973                         "fix conflicts and then commit the result.\n"));
 974         return 1;
 975 }
 976
 977 static struct commit *is_old_style_invocation(int argc, const char **argv,
 978                                               const unsigned char *head)
 979 {
 980         struct commit *second_token = NULL;
 981         if (argc > 2) {
 982                 unsigned char second_sha1[20];
 983
 984                 if (get_sha1(argv[1], second_sha1))
 985                         return NULL;
 986                 second_token = lookup_commit_reference_gently(second_sha1, 0);
 987                 if (!second_token)
 988                         die(_("'%s' is not a commit"), argv[1]);
 989                 if (hashcmp(second_token->object.sha1, head))
 990                         return NULL;
 991         }
 992         return second_token;
 993 }
 994
 995 static int evaluate_result(void)
 996 {
 997         int cnt = 0;
 998         struct rev_info rev;
 999
1000         /* Check how many files differ. */
1001         init_revisions(&rev, "");
1002         setup_revisions(0, NULL, &rev, NULL);
1003         rev.diffopt.output_format |=
1004                 DIFF_FORMAT_CALLBACK;
1005         rev.diffopt.format_callback = count_diff_files;
1006         rev.diffopt.format_callback_data = &cnt;
1007         run_diff_files(&rev, 0);
1008
1009         /*
1010          * Check how many unmerged entries are
1011          * there.
1012          */
1013         cnt += count_unmerged_entries();
1014
1015         return cnt;
1016 }
1017
1018 /*
1019  * Pretend as if the user told us to merge with the tracking
1020  * branch we have for the upstream of the current branch
1021  */
1022 static int setup_with_upstream(const char ***argv)
1023 {
1024         struct branch *branch = branch_get(NULL);
1025         int i;
1026         const char **args;
1027
1028         if (!branch)
1029                 die(_("No current branch."));
1030         if (!branch->remote)
1031                 die(_("No remote for the current branch."));
1032         if (!branch->merge_nr)
1033                 die(_("No default upstream defined for the current branch."));
1034
1035         args = xcalloc(branch->merge_nr + 1, sizeof(char *));
1036         for (i = 0; i < branch->merge_nr; i++) {
1037                 if (!branch->merge[i]->dst)
1038                         die(_("No remote tracking branch for %s from %s"),
1039                             branch->merge[i]->src, branch->remote_name);
1040                 args[i] = branch->merge[i]->dst;
1041         }
1042         args[i] = NULL;
1043         *argv = args;
1044         return i;
1045 }
1046
1047 static void write_merge_state(void)
1048 {
1049         const char *filename;
1050         int fd;
1051         struct commit_list *j;
1052         struct strbuf buf = STRBUF_INIT;
1053
1054         for (j = remoteheads; j; j = j->next) {
1055                 unsigned const char *sha1;
1056                 struct commit *c = j->item;
1057                 if (c->util && merge_remote_util(c)->obj) {
1058                         sha1 = merge_remote_util(c)->obj->sha1;
1059                 } else {
1060                         sha1 = c->object.sha1;
1061                 }
1062                 strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
1063         }
1064         filename = git_path("MERGE_HEAD");
1065         fd = open(filename, O_WRONLY | O_CREAT, 0666);
1066         if (fd < 0)
1067                 die_errno(_("Could not open '%s' for writing"), filename);
1068         if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1069                 die_errno(_("Could not write to '%s'"), filename);
1070         close(fd);
1071         strbuf_addch(&merge_msg, '\n');
1072         write_merge_msg(&merge_msg);
1073
1074         filename = git_path("MERGE_MODE");
1075         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
1076         if (fd < 0)
1077                 die_errno(_("Could not open '%s' for writing"), filename);
1078         strbuf_reset(&buf);
1079         if (!allow_fast_forward)
1080                 strbuf_addf(&buf, "no-ff");
1081         if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1082                 die_errno(_("Could not write to '%s'"), filename);
1083         close(fd);
1084 }
1085
1086 int cmd_merge(int argc, const char **argv, const char *prefix)
1087 {
1088         unsigned char result_tree[20];
1089         unsigned char stash[20];
1090         unsigned char head_sha1[20];
1091         struct commit *head_commit;
1092         struct strbuf buf = STRBUF_INIT;
1093         const char *head_arg;
1094         int flag, i;
1095         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
1096         struct commit_list *common = NULL;
1097         const char *best_strategy = NULL, *wt_strategy = NULL;
1098         struct commit_list **remotes = &remoteheads;
1099
1100         if (argc == 2 && !strcmp(argv[1], "-h"))
1101                 usage_with_options(builtin_merge_usage, builtin_merge_options);
1102
1103         /*
1104          * Check if we are _not_ on a detached HEAD, i.e. if there is a
1105          * current branch.
1106          */
1107         branch = resolve_ref("HEAD", head_sha1, 0, &flag);
1108         if (branch && !prefixcmp(branch, "refs/heads/"))
1109                 branch += 11;
1110         if (!branch || is_null_sha1(head_sha1))
1111                 head_commit = NULL;
1112         else
1113                 head_commit = lookup_commit_or_die(head_sha1, "HEAD");
1114
1115         git_config(git_merge_config, NULL);
1116
1117         if (branch_mergeoptions)
1118                 parse_branch_merge_options(branch_mergeoptions);
1119         argc = parse_options(argc, argv, prefix, builtin_merge_options,
1120                         builtin_merge_usage, 0);
1121         if (shortlog_len < 0)
1122                 shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;
1123
1124         if (verbosity < 0 && show_progress == -1)
1125                 show_progress = 0;
1126
1127         if (abort_current_merge) {
1128                 int nargc = 2;
1129                 const char *nargv[] = {"reset", "--merge", NULL};
1130
1131                 if (!file_exists(git_path("MERGE_HEAD")))
1132                         die(_("There is no merge to abort (MERGE_HEAD missing)."));
1133
1134                 /* Invoke 'git reset --merge' */
1135                 return cmd_reset(nargc, nargv, prefix);
1136         }
1137
1138         if (read_cache_unmerged())
1139                 die_resolve_conflict("merge");
1140
1141         if (file_exists(git_path("MERGE_HEAD"))) {
1142                 /*
1143                  * There is no unmerged entry, don't advise 'git
1144                  * add/rm <file>', just 'git commit'.
1145                  */
1146                 if (advice_resolve_conflict)
1147                         die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1148                                   "Please, commit your changes before you can merge."));
1149                 else
1150                         die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1151         }
1152         if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
1153                 if (advice_resolve_conflict)
1154                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1155                             "Please, commit your changes before you can merge."));
1156                 else
1157                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
1158         }
1159         resolve_undo_clear();
1160
1161         if (verbosity < 0)
1162                 show_diffstat = 0;
1163
1164         if (squash) {
1165                 if (!allow_fast_forward)
1166                         die(_("You cannot combine --squash with --no-ff."));
1167                 option_commit = 0;
1168         }
1169
1170         if (!allow_fast_forward && fast_forward_only)
1171                 die(_("You cannot combine --no-ff with --ff-only."));
1172
1173         if (!abort_current_merge) {
1174                 if (!argc) {
1175                         if (default_to_upstream)
1176                                 argc = setup_with_upstream(&argv);
1177                         else
1178                                 die(_("No commit specified and merge.defaultToUpstream not set."));
1179                 } else if (argc == 1 && !strcmp(argv[0], "-"))
1180                         argv[0] = "@{-1}";
1181         }
1182         if (!argc)
1183                 usage_with_options(builtin_merge_usage,
1184                         builtin_merge_options);
1185
1186         /*
1187          * This could be traditional "merge <msg> HEAD <commit>..."  and
1188          * the way we can tell it is to see if the second token is HEAD,
1189          * but some people might have misused the interface and used a
1190          * committish that is the same as HEAD there instead.
1191          * Traditional format never would have "-m" so it is an
1192          * additional safety measure to check for it.
1193          */
1194
1195         if (!have_message && head_commit &&
1196             is_old_style_invocation(argc, argv, head_commit->object.sha1)) {
1197                 strbuf_addstr(&merge_msg, argv[0]);
1198                 head_arg = argv[1];
1199                 argv += 2;
1200                 argc -= 2;
1201         } else if (!head_commit) {
1202                 struct commit *remote_head;
1203                 /*
1204                  * If the merged head is a valid one there is no reason
1205                  * to forbid "git merge" into a branch yet to be born.
1206                  * We do the same for "git pull".
1207                  */
1208                 if (argc != 1)
1209                         die(_("Can merge only exactly one commit into "
1210                                 "empty head"));
1211                 if (squash)
1212                         die(_("Squash commit into empty head not supported yet"));
1213                 if (!allow_fast_forward)
1214                         die(_("Non-fast-forward commit does not make sense into "
1215                             "an empty head"));
1216                 remote_head = get_merge_parent(argv[0]);
1217                 if (!remote_head)
1218                         die(_("%s - not something we can merge"), argv[0]);
1219                 read_empty(remote_head->object.sha1, 0);
1220                 update_ref("initial pull", "HEAD", remote_head->object.sha1,
1221                            NULL, 0, DIE_ON_ERR);
1222                 return 0;
1223         } else {
1224                 struct strbuf merge_names = STRBUF_INIT;
1225
1226                 /* We are invoked directly as the first-class UI. */
1227                 head_arg = "HEAD";
1228
1229                 /*
1230                  * All the rest are the commits being merged; prepare
1231                  * the standard merge summary message to be appended
1232                  * to the given message.
1233                  */
1234                 for (i = 0; i < argc; i++)
1235                         merge_name(argv[i], &merge_names);
1236
1237                 if (!have_message || shortlog_len) {
1238                         struct fmt_merge_msg_opts opts;
1239                         memset(&opts, 0, sizeof(opts));
1240                         opts.add_title = !have_message;
1241                         opts.shortlog_len = shortlog_len;
1242
1243                         fmt_merge_msg(&merge_names, &merge_msg, &opts);
1244                         if (merge_msg.len)
1245                                 strbuf_setlen(&merge_msg, merge_msg.len - 1);
1246                 }
1247         }
1248
1249         if (!head_commit || !argc)
1250                 usage_with_options(builtin_merge_usage,
1251                         builtin_merge_options);
1252
1253         strbuf_addstr(&buf, "merge");
1254         for (i = 0; i < argc; i++)
1255                 strbuf_addf(&buf, " %s", argv[i]);
1256         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1257         strbuf_reset(&buf);
1258
1259         for (i = 0; i < argc; i++) {
1260                 struct commit *commit = get_merge_parent(argv[i]);
1261                 if (!commit)
1262                         die(_("%s - not something we can merge"), argv[i]);
1263                 remotes = &commit_list_insert(commit, remotes)->next;
1264                 strbuf_addf(&buf, "GITHEAD_%s",
1265                             sha1_to_hex(commit->object.sha1));
1266                 setenv(buf.buf, argv[i], 1);
1267                 strbuf_reset(&buf);
1268                 if (merge_remote_util(commit) &&
1269                     merge_remote_util(commit)->obj &&
1270                     merge_remote_util(commit)->obj->type == OBJ_TAG) {
1271                         option_edit = 1;
1272                         allow_fast_forward = 0;
1273                 }
1274         }
1275
1276         if (!use_strategies) {
1277                 if (!remoteheads->next)
1278                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1279                 else
1280                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1281         }
1282
1283         for (i = 0; i < use_strategies_nr; i++) {
1284                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
1285                         allow_fast_forward = 0;
1286                 if (use_strategies[i]->attr & NO_TRIVIAL)
1287                         allow_trivial = 0;
1288         }
1289
1290         if (!remoteheads->next)
1291                 common = get_merge_bases(head_commit, remoteheads->item, 1);
1292         else {
1293                 struct commit_list *list = remoteheads;
1294                 commit_list_insert(head_commit, &list);
1295                 common = get_octopus_merge_bases(list);
1296                 free(list);
1297         }
1298
1299         update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.sha1,
1300                    NULL, 0, DIE_ON_ERR);
1301
1302         if (!common)
1303                 ; /* No common ancestors found. We need a real merge. */
1304         else if (!remoteheads->next && !common->next &&
1305                         common->item == remoteheads->item) {
1306                 /*
1307                  * If head can reach all the merge then we are up to date.
1308                  * but first the most common case of merging one remote.
1309                  */
1310                 finish_up_to_date("Already up-to-date.");
1311                 return 0;
1312         } else if (allow_fast_forward && !remoteheads->next &&
1313                         !common->next &&
1314                         !hashcmp(common->item->object.sha1, head_commit->object.sha1)) {
1315                 /* Again the most common case of merging one remote. */
1316                 struct strbuf msg = STRBUF_INIT;
1317                 struct commit *commit;
1318                 char hex[41];
1319
1320                 strcpy(hex, find_unique_abbrev(head_commit->object.sha1, DEFAULT_ABBREV));
1321
1322                 if (verbosity >= 0)
1323                         printf(_("Updating %s..%s\n"),
1324                                 hex,
1325                                 find_unique_abbrev(remoteheads->item->object.sha1,
1326                                 DEFAULT_ABBREV));
1327                 strbuf_addstr(&msg, "Fast-forward");
1328                 if (have_message)
1329                         strbuf_addstr(&msg,
1330                                 " (no commit created; -m option ignored)");
1331                 commit = remoteheads->item;
1332                 if (!commit)
1333                         return 1;
1334
1335                 if (checkout_fast_forward(head_commit->object.sha1,
1336                                           commit->object.sha1))
1337                         return 1;
1338
1339                 finish(head_commit, commit->object.sha1, msg.buf);
1340                 drop_save();
1341                 return 0;
1342         } else if (!remoteheads->next && common->next)
1343                 ;
1344                 /*
1345                  * We are not doing octopus and not fast-forward.  Need
1346                  * a real merge.
1347                  */
1348         else if (!remoteheads->next && !common->next && option_commit) {
1349                 /*
1350                  * We are not doing octopus, not fast-forward, and have
1351                  * only one common.
1352                  */
1353                 refresh_cache(REFRESH_QUIET);
1354                 if (allow_trivial && !fast_forward_only) {
1355                         /* See if it is really trivial. */
1356                         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1357                         printf(_("Trying really trivial in-index merge...\n"));
1358                         if (!read_tree_trivial(common->item->object.sha1,
1359                                         head_commit->object.sha1, remoteheads->item->object.sha1))
1360                                 return merge_trivial(head_commit);
1361                         printf(_("Nope.\n"));
1362                 }
1363         } else {
1364                 /*
1365                  * An octopus.  If we can reach all the remote we are up
1366                  * to date.
1367                  */
1368                 int up_to_date = 1;
1369                 struct commit_list *j;
1370
1371                 for (j = remoteheads; j; j = j->next) {
1372                         struct commit_list *common_one;
1373
1374                         /*
1375                          * Here we *have* to calculate the individual
1376                          * merge_bases again, otherwise "git merge HEAD^
1377                          * HEAD^^" would be missed.
1378                          */
1379                         common_one = get_merge_bases(head_commit, j->item, 1);
1380                         if (hashcmp(common_one->item->object.sha1,
1381                                 j->item->object.sha1)) {
1382                                 up_to_date = 0;
1383                                 break;
1384                         }
1385                 }
1386                 if (up_to_date) {
1387                         finish_up_to_date("Already up-to-date. Yeeah!");
1388                         return 0;
1389                 }
1390         }
1391
1392         if (fast_forward_only)
1393                 die(_("Not possible to fast-forward, aborting."));
1394
1395         /* We are going to make a new commit. */
1396         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1397
1398         /*
1399          * At this point, we need a real merge.  No matter what strategy
1400          * we use, it would operate on the index, possibly affecting the
1401          * working tree, and when resolved cleanly, have the desired
1402          * tree in the index -- this means that the index must be in
1403          * sync with the head commit.  The strategies are responsible
1404          * to ensure this.
1405          */
1406         if (use_strategies_nr == 1 ||
1407             /*
1408              * Stash away the local changes so that we can try more than one.
1409              */
1410             save_state(stash))
1411                 hashcpy(stash, null_sha1);
1412
1413         for (i = 0; i < use_strategies_nr; i++) {
1414                 int ret;
1415                 if (i) {
1416                         printf(_("Rewinding the tree to pristine...\n"));
1417                         restore_state(head_commit->object.sha1, stash);
1418                 }
1419                 if (use_strategies_nr != 1)
1420                         printf(_("Trying merge strategy %s...\n"),
1421                                 use_strategies[i]->name);
1422                 /*
1423                  * Remember which strategy left the state in the working
1424                  * tree.
1425                  */
1426                 wt_strategy = use_strategies[i]->name;
1427
1428                 ret = try_merge_strategy(use_strategies[i]->name,
1429                                          common, head_commit, head_arg);
1430                 if (!option_commit && !ret) {
1431                         merge_was_ok = 1;
1432                         /*
1433                          * This is necessary here just to avoid writing
1434                          * the tree, but later we will *not* exit with
1435                          * status code 1 because merge_was_ok is set.
1436                          */
1437                         ret = 1;
1438                 }
1439
1440                 if (ret) {
1441                         /*
1442                          * The backend exits with 1 when conflicts are
1443                          * left to be resolved, with 2 when it does not
1444                          * handle the given merge at all.
1445                          */
1446                         if (ret == 1) {
1447                                 int cnt = evaluate_result();
1448
1449                                 if (best_cnt <= 0 || cnt <= best_cnt) {
1450                                         best_strategy = use_strategies[i]->name;
1451                                         best_cnt = cnt;
1452                                 }
1453                         }
1454                         if (merge_was_ok)
1455                                 break;
1456                         else
1457                                 continue;
1458                 }
1459
1460                 /* Automerge succeeded. */
1461                 write_tree_trivial(result_tree);
1462                 automerge_was_ok = 1;
1463                 break;
1464         }
1465
1466         /*
1467          * If we have a resulting tree, that means the strategy module
1468          * auto resolved the merge cleanly.
1469          */
1470         if (automerge_was_ok)
1471                 return finish_automerge(head_commit, common, result_tree,
1472                                         wt_strategy);
1473
1474         /*
1475          * Pick the result from the best strategy and have the user fix
1476          * it up.
1477          */
1478         if (!best_strategy) {
1479                 restore_state(head_commit->object.sha1, stash);
1480                 if (use_strategies_nr > 1)
1481                         fprintf(stderr,
1482                                 _("No merge strategy handled the merge.\n"));
1483                 else
1484                         fprintf(stderr, _("Merge with strategy %s failed.\n"),
1485                                 use_strategies[0]->name);
1486                 return 2;
1487         } else if (best_strategy == wt_strategy)
1488                 ; /* We already have its result in the working tree. */
1489         else {
1490                 printf(_("Rewinding the tree to pristine...\n"));
1491                 restore_state(head_commit->object.sha1, stash);
1492                 printf(_("Using the %s to prepare resolving by hand.\n"),
1493                         best_strategy);
1494                 try_merge_strategy(best_strategy, common, head_commit, head_arg);
1495         }
1496
1497         if (squash)
1498                 finish(head_commit, NULL, NULL);
1499         else
1500                 write_merge_state();
1501
1502         if (merge_was_ok) {
1503                 fprintf(stderr, _("Automatic merge went well; "
1504                         "stopped before committing as requested\n"));
1505                 return 0;
1506         } else
1507                 return suggest_conflicts(option_renormalize);
1508 }