git.oblomov.eu Git - git/blob - 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 #define USE_THE_INDEX_COMPATIBILITY_MACROS
  10 #include "cache.h"
  11 #include "config.h"
  12 #include "parse-options.h"
  13 #include "builtin.h"
  14 #include "lockfile.h"
  15 #include "run-command.h"
  16 #include "diff.h"
  17 #include "refs.h"
  18 #include "refspec.h"
  19 #include "commit.h"
  20 #include "diffcore.h"
  21 #include "revision.h"
  22 #include "unpack-trees.h"
  23 #include "cache-tree.h"
  24 #include "dir.h"
  25 #include "utf8.h"
  26 #include "log-tree.h"
  27 #include "color.h"
  28 #include "rerere.h"
  29 #include "help.h"
  30 #include "merge-recursive.h"
  31 #include "resolve-undo.h"
  32 #include "remote.h"
  33 #include "fmt-merge-msg.h"
  34 #include "gpg-interface.h"
  35 #include "sequencer.h"
  36 #include "string-list.h"
  37 #include "packfile.h"
  38 #include "tag.h"
  39 #include "alias.h"
  40 #include "branch.h"
  41 #include "commit-reach.h"
  42 #include "wt-status.h"
  43
  44 #define DEFAULT_TWOHEAD (1<<0)
  45 #define DEFAULT_OCTOPUS (1<<1)
  46 #define NO_FAST_FORWARD (1<<2)
  47 #define NO_TRIVIAL      (1<<3)
  48
  49 struct strategy {
  50         const char *name;
  51         unsigned attr;
  52 };
  53
  54 static const char * const builtin_merge_usage[] = {
  55         N_("git merge [<options>] [<commit>...]"),
  56         N_("git merge --abort"),
  57         N_("git merge --continue"),
  58         NULL
  59 };
  60
  61 static int show_diffstat = 1, shortlog_len = -1, squash;
  62 static int option_commit = -1;
  63 static int option_edit = -1;
  64 static int allow_trivial = 1, have_message, verify_signatures;
  65 static int check_trust_level = 1;
  66 static int overwrite_ignore = 1;
  67 static struct strbuf merge_msg = STRBUF_INIT;
  68 static struct strategy **use_strategies;
  69 static size_t use_strategies_nr, use_strategies_alloc;
  70 static const char **xopts;
  71 static size_t xopts_nr, xopts_alloc;
  72 static const char *branch;
  73 static char *branch_mergeoptions;
  74 static int option_renormalize;
  75 static int verbosity;
  76 static int allow_rerere_auto;
  77 static int abort_current_merge;
  78 static int quit_current_merge;
  79 static int continue_current_merge;
  80 static int allow_unrelated_histories;
  81 static int show_progress = -1;
  82 static int default_to_upstream = 1;
  83 static int signoff;
  84 static const char *sign_commit;
  85 static int no_verify;
  86
  87 static struct strategy all_strategy[] = {
  88         { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
  89         { "octopus",    DEFAULT_OCTOPUS },
  90         { "resolve",    0 },
  91         { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
  92         { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
  93 };
  94
  95 static const char *pull_twohead, *pull_octopus;
  96
  97 enum ff_type {
  98         FF_NO,
  99         FF_ALLOW,
 100         FF_ONLY
 101 };
 102
 103 static enum ff_type fast_forward = FF_ALLOW;
 104
 105 static const char *cleanup_arg;
 106 static enum commit_msg_cleanup_mode cleanup_mode;
 107
 108 static int option_parse_message(const struct option *opt,
 109                                 const char *arg, int unset)
 110 {
 111         struct strbuf *buf = opt->value;
 112
 113         if (unset)
 114                 strbuf_setlen(buf, 0);
 115         else if (arg) {
 116                 strbuf_addf(buf, "%s%s", buf->len ? "\n\n" : "", arg);
 117                 have_message = 1;
 118         } else
 119                 return error(_("switch `m' requires a value"));
 120         return 0;
 121 }
 122
 123 static enum parse_opt_result option_read_message(struct parse_opt_ctx_t *ctx,
 124                                                  const struct option *opt,
 125                                                  const char *arg_not_used,
 126                                                  int unset)
 127 {
 128         struct strbuf *buf = opt->value;
 129         const char *arg;
 130
 131         BUG_ON_OPT_ARG(arg_not_used);
 132         if (unset)
 133                 BUG("-F cannot be negated");
 134
 135         if (ctx->opt) {
 136                 arg = ctx->opt;
 137                 ctx->opt = NULL;
 138         } else if (ctx->argc > 1) {
 139                 ctx->argc--;
 140                 arg = *++ctx->argv;
 141         } else
 142                 return error(_("option `%s' requires a value"), opt->long_name);
 143
 144         if (buf->len)
 145                 strbuf_addch(buf, '\n');
 146         if (ctx->prefix && !is_absolute_path(arg))
 147                 arg = prefix_filename(ctx->prefix, arg);
 148         if (strbuf_read_file(buf, arg, 0) < 0)
 149                 return error(_("could not read file '%s'"), arg);
 150         have_message = 1;
 151
 152         return 0;
 153 }
 154
 155 static struct strategy *get_strategy(const char *name)
 156 {
 157         int i;
 158         struct strategy *ret;
 159         static struct cmdnames main_cmds, other_cmds;
 160         static int loaded;
 161
 162         if (!name)
 163                 return NULL;
 164
 165         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 166                 if (!strcmp(name, all_strategy[i].name))
 167                         return &all_strategy[i];
 168
 169         if (!loaded) {
 170                 struct cmdnames not_strategies;
 171                 loaded = 1;
 172
 173                 memset(&not_strategies, 0, sizeof(struct cmdnames));
 174                 load_command_list("git-merge-", &main_cmds, &other_cmds);
 175                 for (i = 0; i < main_cmds.cnt; i++) {
 176                         int j, found = 0;
 177                         struct cmdname *ent = main_cmds.names[i];
 178                         for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
 179                                 if (!strncmp(ent->name, all_strategy[j].name, ent->len)
 180                                                 && !all_strategy[j].name[ent->len])
 181                                         found = 1;
 182                         if (!found)
 183                                 add_cmdname(&not_strategies, ent->name, ent->len);
 184                 }
 185                 exclude_cmds(&main_cmds, &not_strategies);
 186         }
 187         if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
 188                 fprintf(stderr, _("Could not find merge strategy '%s'.\n"), name);
 189                 fprintf(stderr, _("Available strategies are:"));
 190                 for (i = 0; i < main_cmds.cnt; i++)
 191                         fprintf(stderr, " %s", main_cmds.names[i]->name);
 192                 fprintf(stderr, ".\n");
 193                 if (other_cmds.cnt) {
 194                         fprintf(stderr, _("Available custom strategies are:"));
 195                         for (i = 0; i < other_cmds.cnt; i++)
 196                                 fprintf(stderr, " %s", other_cmds.names[i]->name);
 197                         fprintf(stderr, ".\n");
 198                 }
 199                 exit(1);
 200         }
 201
 202         ret = xcalloc(1, sizeof(struct strategy));
 203         ret->name = xstrdup(name);
 204         ret->attr = NO_TRIVIAL;
 205         return ret;
 206 }
 207
 208 static void append_strategy(struct strategy *s)
 209 {
 210         ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
 211         use_strategies[use_strategies_nr++] = s;
 212 }
 213
 214 static int option_parse_strategy(const struct option *opt,
 215                                  const char *name, int unset)
 216 {
 217         if (unset)
 218                 return 0;
 219
 220         append_strategy(get_strategy(name));
 221         return 0;
 222 }
 223
 224 static int option_parse_x(const struct option *opt,
 225                           const char *arg, int unset)
 226 {
 227         if (unset)
 228                 return 0;
 229
 230         ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
 231         xopts[xopts_nr++] = xstrdup(arg);
 232         return 0;
 233 }
 234
 235 static int option_parse_n(const struct option *opt,
 236                           const char *arg, int unset)
 237 {
 238         BUG_ON_OPT_ARG(arg);
 239         show_diffstat = unset;
 240         return 0;
 241 }
 242
 243 static struct option builtin_merge_options[] = {
 244         { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
 245                 N_("do not show a diffstat at the end of the merge"),
 246                 PARSE_OPT_NOARG, option_parse_n },
 247         OPT_BOOL(0, "stat", &show_diffstat,
 248                 N_("show a diffstat at the end of the merge")),
 249         OPT_BOOL(0, "summary", &show_diffstat, N_("(synonym to --stat)")),
 250         { OPTION_INTEGER, 0, "log", &shortlog_len, N_("n"),
 251           N_("add (at most <n>) entries from shortlog to merge commit message"),
 252           PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
 253         OPT_BOOL(0, "squash", &squash,
 254                 N_("create a single commit instead of doing a merge")),
 255         OPT_BOOL(0, "commit", &option_commit,
 256                 N_("perform a commit if the merge succeeds (default)")),
 257         OPT_BOOL('e', "edit", &option_edit,
 258                 N_("edit message before committing")),
 259         OPT_CLEANUP(&cleanup_arg),
 260         OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
 261         OPT_SET_INT_F(0, "ff-only", &fast_forward,
 262                       N_("abort if fast-forward is not possible"),
 263                       FF_ONLY, PARSE_OPT_NONEG),
 264         OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
 265         OPT_BOOL(0, "verify-signatures", &verify_signatures,
 266                 N_("verify that the named commit has a valid GPG signature")),
 267         OPT_CALLBACK('s', "strategy", &use_strategies, N_("strategy"),
 268                 N_("merge strategy to use"), option_parse_strategy),
 269         OPT_CALLBACK('X', "strategy-option", &xopts, N_("option=value"),
 270                 N_("option for selected merge strategy"), option_parse_x),
 271         OPT_CALLBACK('m', "message", &merge_msg, N_("message"),
 272                 N_("merge commit message (for a non-fast-forward merge)"),
 273                 option_parse_message),
 274         { OPTION_LOWLEVEL_CALLBACK, 'F', "file", &merge_msg, N_("path"),
 275                 N_("read message from file"), PARSE_OPT_NONEG,
 276                 NULL, 0, option_read_message },
 277         OPT__VERBOSITY(&verbosity),
 278         OPT_BOOL(0, "abort", &abort_current_merge,
 279                 N_("abort the current in-progress merge")),
 280         OPT_BOOL(0, "quit", &quit_current_merge,
 281                 N_("--abort but leave index and working tree alone")),
 282         OPT_BOOL(0, "continue", &continue_current_merge,
 283                 N_("continue the current in-progress merge")),
 284         OPT_BOOL(0, "allow-unrelated-histories", &allow_unrelated_histories,
 285                  N_("allow merging unrelated histories")),
 286         OPT_SET_INT(0, "progress", &show_progress, N_("force progress reporting"), 1),
 287         { OPTION_STRING, 'S', "gpg-sign", &sign_commit, N_("key-id"),
 288           N_("GPG sign commit"), PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
 289         OPT_BOOL(0, "overwrite-ignore", &overwrite_ignore, N_("update ignored files (default)")),
 290         OPT_BOOL(0, "signoff", &signoff, N_("add Signed-off-by:")),
 291         OPT_BOOL(0, "no-verify", &no_verify, N_("bypass pre-merge-commit and commit-msg hooks")),
 292         OPT_END()
 293 };
 294
 295 static int save_state(struct object_id *stash)
 296 {
 297         int len;
 298         struct child_process cp = CHILD_PROCESS_INIT;
 299         struct strbuf buffer = STRBUF_INIT;
 300         const char *argv[] = {"stash", "create", NULL};
 301         int rc = -1;
 302
 303         cp.argv = argv;
 304         cp.out = -1;
 305         cp.git_cmd = 1;
 306
 307         if (start_command(&cp))
 308                 die(_("could not run stash."));
 309         len = strbuf_read(&buffer, cp.out, 1024);
 310         close(cp.out);
 311
 312         if (finish_command(&cp) || len < 0)
 313                 die(_("stash failed"));
 314         else if (!len)          /* no changes */
 315                 goto out;
 316         strbuf_setlen(&buffer, buffer.len-1);
 317         if (get_oid(buffer.buf, stash))
 318                 die(_("not a valid object: %s"), buffer.buf);
 319         rc = 0;
 320 out:
 321         strbuf_release(&buffer);
 322         return rc;
 323 }
 324
 325 static void read_empty(const struct object_id *oid, int verbose)
 326 {
 327         int i = 0;
 328         const char *args[7];
 329
 330         args[i++] = "read-tree";
 331         if (verbose)
 332                 args[i++] = "-v";
 333         args[i++] = "-m";
 334         args[i++] = "-u";
 335         args[i++] = empty_tree_oid_hex();
 336         args[i++] = oid_to_hex(oid);
 337         args[i] = NULL;
 338
 339         if (run_command_v_opt(args, RUN_GIT_CMD))
 340                 die(_("read-tree failed"));
 341 }
 342
 343 static void reset_hard(const struct object_id *oid, int verbose)
 344 {
 345         int i = 0;
 346         const char *args[6];
 347
 348         args[i++] = "read-tree";
 349         if (verbose)
 350                 args[i++] = "-v";
 351         args[i++] = "--reset";
 352         args[i++] = "-u";
 353         args[i++] = oid_to_hex(oid);
 354         args[i] = NULL;
 355
 356         if (run_command_v_opt(args, RUN_GIT_CMD))
 357                 die(_("read-tree failed"));
 358 }
 359
 360 static void restore_state(const struct object_id *head,
 361                           const struct object_id *stash)
 362 {
 363         struct strbuf sb = STRBUF_INIT;
 364         const char *args[] = { "stash", "apply", NULL, NULL };
 365
 366         if (is_null_oid(stash))
 367                 return;
 368
 369         reset_hard(head, 1);
 370
 371         args[2] = oid_to_hex(stash);
 372
 373         /*
 374          * It is OK to ignore error here, for example when there was
 375          * nothing to restore.
 376          */
 377         run_command_v_opt(args, RUN_GIT_CMD);
 378
 379         strbuf_release(&sb);
 380         refresh_cache(REFRESH_QUIET);
 381 }
 382
 383 /* This is called when no merge was necessary. */
 384 static void finish_up_to_date(const char *msg)
 385 {
 386         if (verbosity >= 0)
 387                 printf("%s%s\n", squash ? _(" (nothing to squash)") : "", msg);
 388         remove_merge_branch_state(the_repository);
 389 }
 390
 391 static void squash_message(struct commit *commit, struct commit_list *remoteheads)
 392 {
 393         struct rev_info rev;
 394         struct strbuf out = STRBUF_INIT;
 395         struct commit_list *j;
 396         struct pretty_print_context ctx = {0};
 397
 398         printf(_("Squash commit -- not updating HEAD\n"));
 399
 400         repo_init_revisions(the_repository, &rev, NULL);
 401         rev.ignore_merges = 1;
 402         rev.commit_format = CMIT_FMT_MEDIUM;
 403
 404         commit->object.flags |= UNINTERESTING;
 405         add_pending_object(&rev, &commit->object, NULL);
 406
 407         for (j = remoteheads; j; j = j->next)
 408                 add_pending_object(&rev, &j->item->object, NULL);
 409
 410         setup_revisions(0, NULL, &rev, NULL);
 411         if (prepare_revision_walk(&rev))
 412                 die(_("revision walk setup failed"));
 413
 414         ctx.abbrev = rev.abbrev;
 415         ctx.date_mode = rev.date_mode;
 416         ctx.fmt = rev.commit_format;
 417
 418         strbuf_addstr(&out, "Squashed commit of the following:\n");
 419         while ((commit = get_revision(&rev)) != NULL) {
 420                 strbuf_addch(&out, '\n');
 421                 strbuf_addf(&out, "commit %s\n",
 422                         oid_to_hex(&commit->object.oid));
 423                 pretty_print_commit(&ctx, commit, &out);
 424         }
 425         write_file_buf(git_path_squash_msg(the_repository), out.buf, out.len);
 426         strbuf_release(&out);
 427 }
 428
 429 static void finish(struct commit *head_commit,
 430                    struct commit_list *remoteheads,
 431                    const struct object_id *new_head, const char *msg)
 432 {
 433         struct strbuf reflog_message = STRBUF_INIT;
 434         const struct object_id *head = &head_commit->object.oid;
 435
 436         if (!msg)
 437                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
 438         else {
 439                 if (verbosity >= 0)
 440                         printf("%s\n", msg);
 441                 strbuf_addf(&reflog_message, "%s: %s",
 442                         getenv("GIT_REFLOG_ACTION"), msg);
 443         }
 444         if (squash) {
 445                 squash_message(head_commit, remoteheads);
 446         } else {
 447                 if (verbosity >= 0 && !merge_msg.len)
 448                         printf(_("No merge message -- not updating HEAD\n"));
 449                 else {
 450                         update_ref(reflog_message.buf, "HEAD", new_head, head,
 451                                    0, UPDATE_REFS_DIE_ON_ERR);
 452                         /*
 453                          * We ignore errors in 'gc --auto', since the
 454                          * user should see them.
 455                          */
 456                         close_object_store(the_repository->objects);
 457                         run_auto_gc(verbosity < 0);
 458                 }
 459         }
 460         if (new_head && show_diffstat) {
 461                 struct diff_options opts;
 462                 repo_diff_setup(the_repository, &opts);
 463                 opts.stat_width = -1; /* use full terminal width */
 464                 opts.stat_graph_width = -1; /* respect statGraphWidth config */
 465                 opts.output_format |=
 466                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 467                 opts.detect_rename = DIFF_DETECT_RENAME;
 468                 diff_setup_done(&opts);
 469                 diff_tree_oid(head, new_head, "", &opts);
 470                 diffcore_std(&opts);
 471                 diff_flush(&opts);
 472         }
 473
 474         /* Run a post-merge hook */
 475         run_hook_le(NULL, "post-merge", squash ? "1" : "0", NULL);
 476
 477         strbuf_release(&reflog_message);
 478 }
 479
 480 /* Get the name for the merge commit's message. */
 481 static void merge_name(const char *remote, struct strbuf *msg)
 482 {
 483         struct commit *remote_head;
 484         struct object_id branch_head;
 485         struct strbuf buf = STRBUF_INIT;
 486         struct strbuf bname = STRBUF_INIT;
 487         struct merge_remote_desc *desc;
 488         const char *ptr;
 489         char *found_ref;
 490         int len, early;
 491
 492         strbuf_branchname(&bname, remote, 0);
 493         remote = bname.buf;
 494
 495         oidclr(&branch_head);
 496         remote_head = get_merge_parent(remote);
 497         if (!remote_head)
 498                 die(_("'%s' does not point to a commit"), remote);
 499
 500         if (dwim_ref(remote, strlen(remote), &branch_head, &found_ref) > 0) {
 501                 if (starts_with(found_ref, "refs/heads/")) {
 502                         strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 503                                     oid_to_hex(&branch_head), remote);
 504                         goto cleanup;
 505                 }
 506                 if (starts_with(found_ref, "refs/tags/")) {
 507                         strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
 508                                     oid_to_hex(&branch_head), remote);
 509                         goto cleanup;
 510                 }
 511                 if (starts_with(found_ref, "refs/remotes/")) {
 512                         strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
 513                                     oid_to_hex(&branch_head), remote);
 514                         goto cleanup;
 515                 }
 516         }
 517
 518         /* See if remote matches <name>^^^.. or <name>~<number> */
 519         for (len = 0, ptr = remote + strlen(remote);
 520              remote < ptr && ptr[-1] == '^';
 521              ptr--)
 522                 len++;
 523         if (len)
 524                 early = 1;
 525         else {
 526                 early = 0;
 527                 ptr = strrchr(remote, '~');
 528                 if (ptr) {
 529                         int seen_nonzero = 0;
 530
 531                         len++; /* count ~ */
 532                         while (*++ptr && isdigit(*ptr)) {
 533                                 seen_nonzero |= (*ptr != '0');
 534                                 len++;
 535                         }
 536                         if (*ptr)
 537                                 len = 0; /* not ...~<number> */
 538                         else if (seen_nonzero)
 539                                 early = 1;
 540                         else if (len == 1)
 541                                 early = 1; /* "name~" is "name~1"! */
 542                 }
 543         }
 544         if (len) {
 545                 struct strbuf truname = STRBUF_INIT;
 546                 strbuf_addf(&truname, "refs/heads/%s", remote);
 547                 strbuf_setlen(&truname, truname.len - len);
 548                 if (ref_exists(truname.buf)) {
 549                         strbuf_addf(msg,
 550                                     "%s\t\tbranch '%s'%s of .\n",
 551                                     oid_to_hex(&remote_head->object.oid),
 552                                     truname.buf + 11,
 553                                     (early ? " (early part)" : ""));
 554                         strbuf_release(&truname);
 555                         goto cleanup;
 556                 }
 557                 strbuf_release(&truname);
 558         }
 559
 560         desc = merge_remote_util(remote_head);
 561         if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
 562                 strbuf_addf(msg, "%s\t\t%s '%s'\n",
 563                             oid_to_hex(&desc->obj->oid),
 564                             type_name(desc->obj->type),
 565                             remote);
 566                 goto cleanup;
 567         }
 568
 569         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 570                 oid_to_hex(&remote_head->object.oid), remote);
 571 cleanup:
 572         strbuf_release(&buf);
 573         strbuf_release(&bname);
 574 }
 575
 576 static void parse_branch_merge_options(char *bmo)
 577 {
 578         const char **argv;
 579         int argc;
 580
 581         if (!bmo)
 582                 return;
 583         argc = split_cmdline(bmo, &argv);
 584         if (argc < 0)
 585                 die(_("Bad branch.%s.mergeoptions string: %s"), branch,
 586                     _(split_cmdline_strerror(argc)));
 587         REALLOC_ARRAY(argv, argc + 2);
 588         MOVE_ARRAY(argv + 1, argv, argc + 1);
 589         argc++;
 590         argv[0] = "branch.*.mergeoptions";
 591         parse_options(argc, argv, NULL, builtin_merge_options,
 592                       builtin_merge_usage, 0);
 593         free(argv);
 594 }
 595
 596 static int git_merge_config(const char *k, const char *v, void *cb)
 597 {
 598         int status;
 599
 600         if (branch && starts_with(k, "branch.") &&
 601                 starts_with(k + 7, branch) &&
 602                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
 603                 free(branch_mergeoptions);
 604                 branch_mergeoptions = xstrdup(v);
 605                 return 0;
 606         }
 607
 608         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 609                 show_diffstat = git_config_bool(k, v);
 610         else if (!strcmp(k, "merge.verifysignatures"))
 611                 verify_signatures = git_config_bool(k, v);
 612         else if (!strcmp(k, "pull.twohead"))
 613                 return git_config_string(&pull_twohead, k, v);
 614         else if (!strcmp(k, "pull.octopus"))
 615                 return git_config_string(&pull_octopus, k, v);
 616         else if (!strcmp(k, "commit.cleanup"))
 617                 return git_config_string(&cleanup_arg, k, v);
 618         else if (!strcmp(k, "merge.renormalize"))
 619                 option_renormalize = git_config_bool(k, v);
 620         else if (!strcmp(k, "merge.ff")) {
 621                 int boolval = git_parse_maybe_bool(v);
 622                 if (0 <= boolval) {
 623                         fast_forward = boolval ? FF_ALLOW : FF_NO;
 624                 } else if (v && !strcmp(v, "only")) {
 625                         fast_forward = FF_ONLY;
 626                 } /* do not barf on values from future versions of git */
 627                 return 0;
 628         } else if (!strcmp(k, "merge.defaulttoupstream")) {
 629                 default_to_upstream = git_config_bool(k, v);
 630                 return 0;
 631         } else if (!strcmp(k, "commit.gpgsign")) {
 632                 sign_commit = git_config_bool(k, v) ? "" : NULL;
 633                 return 0;
 634         } else if (!strcmp(k, "gpg.mintrustlevel")) {
 635                 check_trust_level = 0;
 636         }
 637
 638         status = fmt_merge_msg_config(k, v, cb);
 639         if (status)
 640                 return status;
 641         status = git_gpg_config(k, v, NULL);
 642         if (status)
 643                 return status;
 644         return git_diff_ui_config(k, v, cb);
 645 }
 646
 647 static int read_tree_trivial(struct object_id *common, struct object_id *head,
 648                              struct object_id *one)
 649 {
 650         int i, nr_trees = 0;
 651         struct tree *trees[MAX_UNPACK_TREES];
 652         struct tree_desc t[MAX_UNPACK_TREES];
 653         struct unpack_trees_options opts;
 654
 655         memset(&opts, 0, sizeof(opts));
 656         opts.head_idx = 2;
 657         opts.src_index = &the_index;
 658         opts.dst_index = &the_index;
 659         opts.update = 1;
 660         opts.verbose_update = 1;
 661         opts.trivial_merges_only = 1;
 662         opts.merge = 1;
 663         trees[nr_trees] = parse_tree_indirect(common);
 664         if (!trees[nr_trees++])
 665                 return -1;
 666         trees[nr_trees] = parse_tree_indirect(head);
 667         if (!trees[nr_trees++])
 668                 return -1;
 669         trees[nr_trees] = parse_tree_indirect(one);
 670         if (!trees[nr_trees++])
 671                 return -1;
 672         opts.fn = threeway_merge;
 673         cache_tree_free(&active_cache_tree);
 674         for (i = 0; i < nr_trees; i++) {
 675                 parse_tree(trees[i]);
 676                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 677         }
 678         if (unpack_trees(nr_trees, t, &opts))
 679                 return -1;
 680         return 0;
 681 }
 682
 683 static void write_tree_trivial(struct object_id *oid)
 684 {
 685         if (write_cache_as_tree(oid, 0, NULL))
 686                 die(_("git write-tree failed to write a tree"));
 687 }
 688
 689 static int try_merge_strategy(const char *strategy, struct commit_list *common,
 690                               struct commit_list *remoteheads,
 691                               struct commit *head)
 692 {
 693         const char *head_arg = "HEAD";
 694
 695         if (refresh_and_write_cache(REFRESH_QUIET, SKIP_IF_UNCHANGED, 0) < 0)
 696                 return error(_("Unable to write index."));
 697
 698         if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
 699                 struct lock_file lock = LOCK_INIT;
 700                 int clean, x;
 701                 struct commit *result;
 702                 struct commit_list *reversed = NULL;
 703                 struct merge_options o;
 704                 struct commit_list *j;
 705
 706                 if (remoteheads->next) {
 707                         error(_("Not handling anything other than two heads merge."));
 708                         return 2;
 709                 }
 710
 711                 init_merge_options(&o, the_repository);
 712                 if (!strcmp(strategy, "subtree"))
 713                         o.subtree_shift = "";
 714
 715                 o.renormalize = option_renormalize;
 716                 o.show_rename_progress =
 717                         show_progress == -1 ? isatty(2) : show_progress;
 718
 719                 for (x = 0; x < xopts_nr; x++)
 720                         if (parse_merge_opt(&o, xopts[x]))
 721                                 die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
 722
 723                 o.branch1 = head_arg;
 724                 o.branch2 = merge_remote_util(remoteheads->item)->name;
 725
 726                 for (j = common; j; j = j->next)
 727                         commit_list_insert(j->item, &reversed);
 728
 729                 hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
 730                 clean = merge_recursive(&o, head,
 731                                 remoteheads->item, reversed, &result);
 732                 if (clean < 0)
 733                         exit(128);
 734                 if (write_locked_index(&the_index, &lock,
 735                                        COMMIT_LOCK | SKIP_IF_UNCHANGED))
 736                         die(_("unable to write %s"), get_index_file());
 737                 return clean ? 0 : 1;
 738         } else {
 739                 return try_merge_command(the_repository,
 740                                          strategy, xopts_nr, xopts,
 741                                          common, head_arg, remoteheads);
 742         }
 743 }
 744
 745 static void count_diff_files(struct diff_queue_struct *q,
 746                              struct diff_options *opt, void *data)
 747 {
 748         int *count = data;
 749
 750         (*count) += q->nr;
 751 }
 752
 753 static int count_unmerged_entries(void)
 754 {
 755         int i, ret = 0;
 756
 757         for (i = 0; i < active_nr; i++)
 758                 if (ce_stage(active_cache[i]))
 759                         ret++;
 760
 761         return ret;
 762 }
 763
 764 static void add_strategies(const char *string, unsigned attr)
 765 {
 766         int i;
 767
 768         if (string) {
 769                 struct string_list list = STRING_LIST_INIT_DUP;
 770                 struct string_list_item *item;
 771                 string_list_split(&list, string, ' ', -1);
 772                 for_each_string_list_item(item, &list)
 773                         append_strategy(get_strategy(item->string));
 774                 string_list_clear(&list, 0);
 775                 return;
 776         }
 777         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 778                 if (all_strategy[i].attr & attr)
 779                         append_strategy(&all_strategy[i]);
 780
 781 }
 782
 783 static void read_merge_msg(struct strbuf *msg)
 784 {
 785         const char *filename = git_path_merge_msg(the_repository);
 786         strbuf_reset(msg);
 787         if (strbuf_read_file(msg, filename, 0) < 0)
 788                 die_errno(_("Could not read from '%s'"), filename);
 789 }
 790
 791 static void write_merge_state(struct commit_list *);
 792 static void abort_commit(struct commit_list *remoteheads, const char *err_msg)
 793 {
 794         if (err_msg)
 795                 error("%s", err_msg);
 796         fprintf(stderr,
 797                 _("Not committing merge; use 'git commit' to complete the merge.\n"));
 798         write_merge_state(remoteheads);
 799         exit(1);
 800 }
 801
 802 static const char merge_editor_comment[] =
 803 N_("Please enter a commit message to explain why this merge is necessary,\n"
 804    "especially if it merges an updated upstream into a topic branch.\n"
 805    "\n");
 806
 807 static const char scissors_editor_comment[] =
 808 N_("An empty message aborts the commit.\n");
 809
 810 static const char no_scissors_editor_comment[] =
 811 N_("Lines starting with '%c' will be ignored, and an empty message aborts\n"
 812    "the commit.\n");
 813
 814 static void write_merge_heads(struct commit_list *);
 815 static void prepare_to_commit(struct commit_list *remoteheads)
 816 {
 817         struct strbuf msg = STRBUF_INIT;
 818         const char *index_file = get_index_file();
 819
 820         if (!no_verify && run_commit_hook(0 < option_edit, index_file, "pre-merge-commit", NULL))
 821                 abort_commit(remoteheads, NULL);
 822         /*
 823          * Re-read the index as pre-merge-commit hook could have updated it,
 824          * and write it out as a tree.  We must do this before we invoke
 825          * the editor and after we invoke run_status above.
 826          */
 827         if (find_hook("pre-merge-commit"))
 828                 discard_cache();
 829         read_cache_from(index_file);
 830         strbuf_addbuf(&msg, &merge_msg);
 831         if (squash)
 832                 BUG("the control must not reach here under --squash");
 833         if (0 < option_edit) {
 834                 strbuf_addch(&msg, '\n');
 835                 if (cleanup_mode == COMMIT_MSG_CLEANUP_SCISSORS) {
 836                         wt_status_append_cut_line(&msg);
 837                         strbuf_commented_addf(&msg, "\n");
 838                 }
 839                 strbuf_commented_addf(&msg, _(merge_editor_comment));
 840                 strbuf_commented_addf(&msg, _(cleanup_mode == COMMIT_MSG_CLEANUP_SCISSORS ?
 841                         scissors_editor_comment :
 842                         no_scissors_editor_comment), comment_line_char);
 843         }
 844         if (signoff)
 845                 append_signoff(&msg, ignore_non_trailer(msg.buf, msg.len), 0);
 846         write_merge_heads(remoteheads);
 847         write_file_buf(git_path_merge_msg(the_repository), msg.buf, msg.len);
 848         if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
 849                             git_path_merge_msg(the_repository), "merge", NULL))
 850                 abort_commit(remoteheads, NULL);
 851         if (0 < option_edit) {
 852                 if (launch_editor(git_path_merge_msg(the_repository), NULL, NULL))
 853                         abort_commit(remoteheads, NULL);
 854         }
 855
 856         if (!no_verify && run_commit_hook(0 < option_edit, get_index_file(),
 857                                           "commit-msg",
 858                                           git_path_merge_msg(the_repository), NULL))
 859                 abort_commit(remoteheads, NULL);
 860
 861         read_merge_msg(&msg);
 862         cleanup_message(&msg, cleanup_mode, 0);
 863         if (!msg.len)
 864                 abort_commit(remoteheads, _("Empty commit message."));
 865         strbuf_release(&merge_msg);
 866         strbuf_addbuf(&merge_msg, &msg);
 867         strbuf_release(&msg);
 868 }
 869
 870 static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
 871 {
 872         struct object_id result_tree, result_commit;
 873         struct commit_list *parents, **pptr = &parents;
 874
 875         if (refresh_and_write_cache(REFRESH_QUIET, SKIP_IF_UNCHANGED, 0) < 0)
 876                 return error(_("Unable to write index."));
 877
 878         write_tree_trivial(&result_tree);
 879         printf(_("Wonderful.\n"));
 880         pptr = commit_list_append(head, pptr);
 881         pptr = commit_list_append(remoteheads->item, pptr);
 882         prepare_to_commit(remoteheads);
 883         if (commit_tree(merge_msg.buf, merge_msg.len, &result_tree, parents,
 884                         &result_commit, NULL, sign_commit))
 885                 die(_("failed to write commit object"));
 886         finish(head, remoteheads, &result_commit, "In-index merge");
 887         remove_merge_branch_state(the_repository);
 888         return 0;
 889 }
 890
 891 static int finish_automerge(struct commit *head,
 892                             int head_subsumed,
 893                             struct commit_list *common,
 894                             struct commit_list *remoteheads,
 895                             struct object_id *result_tree,
 896                             const char *wt_strategy)
 897 {
 898         struct commit_list *parents = NULL;
 899         struct strbuf buf = STRBUF_INIT;
 900         struct object_id result_commit;
 901
 902         write_tree_trivial(result_tree);
 903         free_commit_list(common);
 904         parents = remoteheads;
 905         if (!head_subsumed || fast_forward == FF_NO)
 906                 commit_list_insert(head, &parents);
 907         prepare_to_commit(remoteheads);
 908         if (commit_tree(merge_msg.buf, merge_msg.len, result_tree, parents,
 909                         &result_commit, NULL, sign_commit))
 910                 die(_("failed to write commit object"));
 911         strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
 912         finish(head, remoteheads, &result_commit, buf.buf);
 913         strbuf_release(&buf);
 914         remove_merge_branch_state(the_repository);
 915         return 0;
 916 }
 917
 918 static int suggest_conflicts(void)
 919 {
 920         const char *filename;
 921         FILE *fp;
 922         struct strbuf msgbuf = STRBUF_INIT;
 923
 924         filename = git_path_merge_msg(the_repository);
 925         fp = xfopen(filename, "a");
 926
 927         /*
 928          * We can't use cleanup_mode because if we're not using the editor,
 929          * get_cleanup_mode will return COMMIT_MSG_CLEANUP_SPACE instead, even
 930          * though the message is meant to be processed later by git-commit.
 931          * Thus, we will get the cleanup mode which is returned when we _are_
 932          * using an editor.
 933          */
 934         append_conflicts_hint(&the_index, &msgbuf,
 935                               get_cleanup_mode(cleanup_arg, 1));
 936         fputs(msgbuf.buf, fp);
 937         strbuf_release(&msgbuf);
 938         fclose(fp);
 939         repo_rerere(the_repository, allow_rerere_auto);
 940         printf(_("Automatic merge failed; "
 941                         "fix conflicts and then commit the result.\n"));
 942         return 1;
 943 }
 944
 945 static int evaluate_result(void)
 946 {
 947         int cnt = 0;
 948         struct rev_info rev;
 949
 950         /* Check how many files differ. */
 951         repo_init_revisions(the_repository, &rev, "");
 952         setup_revisions(0, NULL, &rev, NULL);
 953         rev.diffopt.output_format |=
 954                 DIFF_FORMAT_CALLBACK;
 955         rev.diffopt.format_callback = count_diff_files;
 956         rev.diffopt.format_callback_data = &cnt;
 957         run_diff_files(&rev, 0);
 958
 959         /*
 960          * Check how many unmerged entries are
 961          * there.
 962          */
 963         cnt += count_unmerged_entries();
 964
 965         return cnt;
 966 }
 967
 968 /*
 969  * Pretend as if the user told us to merge with the remote-tracking
 970  * branch we have for the upstream of the current branch
 971  */
 972 static int setup_with_upstream(const char ***argv)
 973 {
 974         struct branch *branch = branch_get(NULL);
 975         int i;
 976         const char **args;
 977
 978         if (!branch)
 979                 die(_("No current branch."));
 980         if (!branch->remote_name)
 981                 die(_("No remote for the current branch."));
 982         if (!branch->merge_nr)
 983                 die(_("No default upstream defined for the current branch."));
 984
 985         args = xcalloc(st_add(branch->merge_nr, 1), sizeof(char *));
 986         for (i = 0; i < branch->merge_nr; i++) {
 987                 if (!branch->merge[i]->dst)
 988                         die(_("No remote-tracking branch for %s from %s"),
 989                             branch->merge[i]->src, branch->remote_name);
 990                 args[i] = branch->merge[i]->dst;
 991         }
 992         args[i] = NULL;
 993         *argv = args;
 994         return i;
 995 }
 996
 997 static void write_merge_heads(struct commit_list *remoteheads)
 998 {
 999         struct commit_list *j;
1000         struct strbuf buf = STRBUF_INIT;
1001
1002         for (j = remoteheads; j; j = j->next) {
1003                 struct object_id *oid;
1004                 struct commit *c = j->item;
1005                 struct merge_remote_desc *desc;
1006
1007                 desc = merge_remote_util(c);
1008                 if (desc && desc->obj) {
1009                         oid = &desc->obj->oid;
1010                 } else {
1011                         oid = &c->object.oid;
1012                 }
1013                 strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
1014         }
1015         write_file_buf(git_path_merge_head(the_repository), buf.buf, buf.len);
1016
1017         strbuf_reset(&buf);
1018         if (fast_forward == FF_NO)
1019                 strbuf_addstr(&buf, "no-ff");
1020         write_file_buf(git_path_merge_mode(the_repository), buf.buf, buf.len);
1021         strbuf_release(&buf);
1022 }
1023
1024 static void write_merge_state(struct commit_list *remoteheads)
1025 {
1026         write_merge_heads(remoteheads);
1027         strbuf_addch(&merge_msg, '\n');
1028         write_file_buf(git_path_merge_msg(the_repository), merge_msg.buf,
1029                        merge_msg.len);
1030 }
1031
1032 static int default_edit_option(void)
1033 {
1034         static const char name[] = "GIT_MERGE_AUTOEDIT";
1035         const char *e = getenv(name);
1036         struct stat st_stdin, st_stdout;
1037
1038         if (have_message)
1039                 /* an explicit -m msg without --[no-]edit */
1040                 return 0;
1041
1042         if (e) {
1043                 int v = git_parse_maybe_bool(e);
1044                 if (v < 0)
1045                         die(_("Bad value '%s' in environment '%s'"), e, name);
1046                 return v;
1047         }
1048
1049         /* Use editor if stdin and stdout are the same and is a tty */
1050         return (!fstat(0, &st_stdin) &&
1051                 !fstat(1, &st_stdout) &&
1052                 isatty(0) && isatty(1) &&
1053                 st_stdin.st_dev == st_stdout.st_dev &&
1054                 st_stdin.st_ino == st_stdout.st_ino &&
1055                 st_stdin.st_mode == st_stdout.st_mode);
1056 }
1057
1058 static struct commit_list *reduce_parents(struct commit *head_commit,
1059                                           int *head_subsumed,
1060                                           struct commit_list *remoteheads)
1061 {
1062         struct commit_list *parents, **remotes;
1063
1064         /*
1065          * Is the current HEAD reachable from another commit being
1066          * merged?  If so we do not want to record it as a parent of
1067          * the resulting merge, unless --no-ff is given.  We will flip
1068          * this variable to 0 when we find HEAD among the independent
1069          * tips being merged.
1070          */
1071         *head_subsumed = 1;
1072
1073         /* Find what parents to record by checking independent ones. */
1074         parents = reduce_heads(remoteheads);
1075         free_commit_list(remoteheads);
1076
1077         remoteheads = NULL;
1078         remotes = &remoteheads;
1079         while (parents) {
1080                 struct commit *commit = pop_commit(&parents);
1081                 if (commit == head_commit)
1082                         *head_subsumed = 0;
1083                 else
1084                         remotes = &commit_list_insert(commit, remotes)->next;
1085         }
1086         return remoteheads;
1087 }
1088
1089 static void prepare_merge_message(struct strbuf *merge_names, struct strbuf *merge_msg)
1090 {
1091         struct fmt_merge_msg_opts opts;
1092
1093         memset(&opts, 0, sizeof(opts));
1094         opts.add_title = !have_message;
1095         opts.shortlog_len = shortlog_len;
1096         opts.credit_people = (0 < option_edit);
1097
1098         fmt_merge_msg(merge_names, merge_msg, &opts);
1099         if (merge_msg->len)
1100                 strbuf_setlen(merge_msg, merge_msg->len - 1);
1101 }
1102
1103 static void handle_fetch_head(struct commit_list **remotes, struct strbuf *merge_names)
1104 {
1105         const char *filename;
1106         int fd, pos, npos;
1107         struct strbuf fetch_head_file = STRBUF_INIT;
1108         const unsigned hexsz = the_hash_algo->hexsz;
1109
1110         if (!merge_names)
1111                 merge_names = &fetch_head_file;
1112
1113         filename = git_path_fetch_head(the_repository);
1114         fd = open(filename, O_RDONLY);
1115         if (fd < 0)
1116                 die_errno(_("could not open '%s' for reading"), filename);
1117
1118         if (strbuf_read(merge_names, fd, 0) < 0)
1119                 die_errno(_("could not read '%s'"), filename);
1120         if (close(fd) < 0)
1121                 die_errno(_("could not close '%s'"), filename);
1122
1123         for (pos = 0; pos < merge_names->len; pos = npos) {
1124                 struct object_id oid;
1125                 char *ptr;
1126                 struct commit *commit;
1127
1128                 ptr = strchr(merge_names->buf + pos, '\n');
1129                 if (ptr)
1130                         npos = ptr - merge_names->buf + 1;
1131                 else
1132                         npos = merge_names->len;
1133
1134                 if (npos - pos < hexsz + 2 ||
1135                     get_oid_hex(merge_names->buf + pos, &oid))
1136                         commit = NULL; /* bad */
1137                 else if (memcmp(merge_names->buf + pos + hexsz, "\t\t", 2))
1138                         continue; /* not-for-merge */
1139                 else {
1140                         char saved = merge_names->buf[pos + hexsz];
1141                         merge_names->buf[pos + hexsz] = '\0';
1142                         commit = get_merge_parent(merge_names->buf + pos);
1143                         merge_names->buf[pos + hexsz] = saved;
1144                 }
1145                 if (!commit) {
1146                         if (ptr)
1147                                 *ptr = '\0';
1148                         die(_("not something we can merge in %s: %s"),
1149                             filename, merge_names->buf + pos);
1150                 }
1151                 remotes = &commit_list_insert(commit, remotes)->next;
1152         }
1153
1154         if (merge_names == &fetch_head_file)
1155                 strbuf_release(&fetch_head_file);
1156 }
1157
1158 static struct commit_list *collect_parents(struct commit *head_commit,
1159                                            int *head_subsumed,
1160                                            int argc, const char **argv,
1161                                            struct strbuf *merge_msg)
1162 {
1163         int i;
1164         struct commit_list *remoteheads = NULL;
1165         struct commit_list **remotes = &remoteheads;
1166         struct strbuf merge_names = STRBUF_INIT, *autogen = NULL;
1167
1168         if (merge_msg && (!have_message || shortlog_len))
1169                 autogen = &merge_names;
1170
1171         if (head_commit)
1172                 remotes = &commit_list_insert(head_commit, remotes)->next;
1173
1174         if (argc == 1 && !strcmp(argv[0], "FETCH_HEAD")) {
1175                 handle_fetch_head(remotes, autogen);
1176                 remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
1177         } else {
1178                 for (i = 0; i < argc; i++) {
1179                         struct commit *commit = get_merge_parent(argv[i]);
1180                         if (!commit)
1181                                 help_unknown_ref(argv[i], "merge",
1182                                                  _("not something we can merge"));
1183                         remotes = &commit_list_insert(commit, remotes)->next;
1184                 }
1185                 remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
1186                 if (autogen) {
1187                         struct commit_list *p;
1188                         for (p = remoteheads; p; p = p->next)
1189                                 merge_name(merge_remote_util(p->item)->name, autogen);
1190                 }
1191         }
1192
1193         if (autogen) {
1194                 prepare_merge_message(autogen, merge_msg);
1195                 strbuf_release(autogen);
1196         }
1197
1198         return remoteheads;
1199 }
1200
1201 static int merging_a_throwaway_tag(struct commit *commit)
1202 {
1203         char *tag_ref;
1204         struct object_id oid;
1205         int is_throwaway_tag = 0;
1206
1207         /* Are we merging a tag? */
1208         if (!merge_remote_util(commit) ||
1209             !merge_remote_util(commit)->obj ||
1210             merge_remote_util(commit)->obj->type != OBJ_TAG)
1211                 return is_throwaway_tag;
1212
1213         /*
1214          * Now we know we are merging a tag object.  Are we downstream
1215          * and following the tags from upstream?  If so, we must have
1216          * the tag object pointed at by "refs/tags/$T" where $T is the
1217          * tagname recorded in the tag object.  We want to allow such
1218          * a "just to catch up" merge to fast-forward.
1219          *
1220          * Otherwise, we are playing an integrator's role, making a
1221          * merge with a throw-away tag from a contributor with
1222          * something like "git pull $contributor $signed_tag".
1223          * We want to forbid such a merge from fast-forwarding
1224          * by default; otherwise we would not keep the signature
1225          * anywhere.
1226          */
1227         tag_ref = xstrfmt("refs/tags/%s",
1228                           ((struct tag *)merge_remote_util(commit)->obj)->tag);
1229         if (!read_ref(tag_ref, &oid) &&
1230             oideq(&oid, &merge_remote_util(commit)->obj->oid))
1231                 is_throwaway_tag = 0;
1232         else
1233                 is_throwaway_tag = 1;
1234         free(tag_ref);
1235         return is_throwaway_tag;
1236 }
1237
1238 int cmd_merge(int argc, const char **argv, const char *prefix)
1239 {
1240         struct object_id result_tree, stash, head_oid;
1241         struct commit *head_commit;
1242         struct strbuf buf = STRBUF_INIT;
1243         int i, ret = 0, head_subsumed;
1244         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
1245         struct commit_list *common = NULL;
1246         const char *best_strategy = NULL, *wt_strategy = NULL;
1247         struct commit_list *remoteheads, *p;
1248         void *branch_to_free;
1249         int orig_argc = argc;
1250
1251         if (argc == 2 && !strcmp(argv[1], "-h"))
1252                 usage_with_options(builtin_merge_usage, builtin_merge_options);
1253
1254         /*
1255          * Check if we are _not_ on a detached HEAD, i.e. if there is a
1256          * current branch.
1257          */
1258         branch = branch_to_free = resolve_refdup("HEAD", 0, &head_oid, NULL);
1259         if (branch)
1260                 skip_prefix(branch, "refs/heads/", &branch);
1261
1262         init_diff_ui_defaults();
1263         git_config(git_merge_config, NULL);
1264
1265         if (!branch || is_null_oid(&head_oid))
1266                 head_commit = NULL;
1267         else
1268                 head_commit = lookup_commit_or_die(&head_oid, "HEAD");
1269
1270         if (branch_mergeoptions)
1271                 parse_branch_merge_options(branch_mergeoptions);
1272         argc = parse_options(argc, argv, prefix, builtin_merge_options,
1273                         builtin_merge_usage, 0);
1274         if (shortlog_len < 0)
1275                 shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;
1276
1277         if (verbosity < 0 && show_progress == -1)
1278                 show_progress = 0;
1279
1280         if (abort_current_merge) {
1281                 int nargc = 2;
1282                 const char *nargv[] = {"reset", "--merge", NULL};
1283
1284                 if (orig_argc != 2)
1285                         usage_msg_opt(_("--abort expects no arguments"),
1286                               builtin_merge_usage, builtin_merge_options);
1287
1288                 if (!file_exists(git_path_merge_head(the_repository)))
1289                         die(_("There is no merge to abort (MERGE_HEAD missing)."));
1290
1291                 /* Invoke 'git reset --merge' */
1292                 ret = cmd_reset(nargc, nargv, prefix);
1293                 goto done;
1294         }
1295
1296         if (quit_current_merge) {
1297                 if (orig_argc != 2)
1298                         usage_msg_opt(_("--quit expects no arguments"),
1299                                       builtin_merge_usage,
1300                                       builtin_merge_options);
1301
1302                 remove_merge_branch_state(the_repository);
1303                 goto done;
1304         }
1305
1306         if (continue_current_merge) {
1307                 int nargc = 1;
1308                 const char *nargv[] = {"commit", NULL};
1309
1310                 if (orig_argc != 2)
1311                         usage_msg_opt(_("--continue expects no arguments"),
1312                               builtin_merge_usage, builtin_merge_options);
1313
1314                 if (!file_exists(git_path_merge_head(the_repository)))
1315                         die(_("There is no merge in progress (MERGE_HEAD missing)."));
1316
1317                 /* Invoke 'git commit' */
1318                 ret = cmd_commit(nargc, nargv, prefix);
1319                 goto done;
1320         }
1321
1322         if (read_cache_unmerged())
1323                 die_resolve_conflict("merge");
1324
1325         if (file_exists(git_path_merge_head(the_repository))) {
1326                 /*
1327                  * There is no unmerged entry, don't advise 'git
1328                  * add/rm <file>', just 'git commit'.
1329                  */
1330                 if (advice_resolve_conflict)
1331                         die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1332                                   "Please, commit your changes before you merge."));
1333                 else
1334                         die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1335         }
1336         if (file_exists(git_path_cherry_pick_head(the_repository))) {
1337                 if (advice_resolve_conflict)
1338                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1339                             "Please, commit your changes before you merge."));
1340                 else
1341                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
1342         }
1343         resolve_undo_clear();
1344
1345         if (option_edit < 0)
1346                 option_edit = default_edit_option();
1347
1348         cleanup_mode = get_cleanup_mode(cleanup_arg, 0 < option_edit);
1349
1350         if (verbosity < 0)
1351                 show_diffstat = 0;
1352
1353         if (squash) {
1354                 if (fast_forward == FF_NO)
1355                         die(_("You cannot combine --squash with --no-ff."));
1356                 if (option_commit > 0)
1357                         die(_("You cannot combine --squash with --commit."));
1358                 /*
1359                  * squash can now silently disable option_commit - this is not
1360                  * a problem as it is only overriding the default, not a user
1361                  * supplied option.
1362                  */
1363                 option_commit = 0;
1364         }
1365
1366         if (option_commit < 0)
1367                 option_commit = 1;
1368
1369         if (!argc) {
1370                 if (default_to_upstream)
1371                         argc = setup_with_upstream(&argv);
1372                 else
1373                         die(_("No commit specified and merge.defaultToUpstream not set."));
1374         } else if (argc == 1 && !strcmp(argv[0], "-")) {
1375                 argv[0] = "@{-1}";
1376         }
1377
1378         if (!argc)
1379                 usage_with_options(builtin_merge_usage,
1380                         builtin_merge_options);
1381
1382         if (!head_commit) {
1383                 /*
1384                  * If the merged head is a valid one there is no reason
1385                  * to forbid "git merge" into a branch yet to be born.
1386                  * We do the same for "git pull".
1387                  */
1388                 struct object_id *remote_head_oid;
1389                 if (squash)
1390                         die(_("Squash commit into empty head not supported yet"));
1391                 if (fast_forward == FF_NO)
1392                         die(_("Non-fast-forward commit does not make sense into "
1393                             "an empty head"));
1394                 remoteheads = collect_parents(head_commit, &head_subsumed,
1395                                               argc, argv, NULL);
1396                 if (!remoteheads)
1397                         die(_("%s - not something we can merge"), argv[0]);
1398                 if (remoteheads->next)
1399                         die(_("Can merge only exactly one commit into empty head"));
1400
1401                 if (verify_signatures)
1402                         verify_merge_signature(remoteheads->item, verbosity,
1403                                                check_trust_level);
1404
1405                 remote_head_oid = &remoteheads->item->object.oid;
1406                 read_empty(remote_head_oid, 0);
1407                 update_ref("initial pull", "HEAD", remote_head_oid, NULL, 0,
1408                            UPDATE_REFS_DIE_ON_ERR);
1409                 goto done;
1410         }
1411
1412         /*
1413          * All the rest are the commits being merged; prepare
1414          * the standard merge summary message to be appended
1415          * to the given message.
1416          */
1417         remoteheads = collect_parents(head_commit, &head_subsumed,
1418                                       argc, argv, &merge_msg);
1419
1420         if (!head_commit || !argc)
1421                 usage_with_options(builtin_merge_usage,
1422                         builtin_merge_options);
1423
1424         if (verify_signatures) {
1425                 for (p = remoteheads; p; p = p->next) {
1426                         verify_merge_signature(p->item, verbosity,
1427                                                check_trust_level);
1428                 }
1429         }
1430
1431         strbuf_addstr(&buf, "merge");
1432         for (p = remoteheads; p; p = p->next)
1433                 strbuf_addf(&buf, " %s", merge_remote_util(p->item)->name);
1434         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1435         strbuf_reset(&buf);
1436
1437         for (p = remoteheads; p; p = p->next) {
1438                 struct commit *commit = p->item;
1439                 strbuf_addf(&buf, "GITHEAD_%s",
1440                             oid_to_hex(&commit->object.oid));
1441                 setenv(buf.buf, merge_remote_util(commit)->name, 1);
1442                 strbuf_reset(&buf);
1443                 if (fast_forward != FF_ONLY && merging_a_throwaway_tag(commit))
1444                         fast_forward = FF_NO;
1445         }
1446
1447         if (!use_strategies) {
1448                 if (!remoteheads)
1449                         ; /* already up-to-date */
1450                 else if (!remoteheads->next)
1451                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1452                 else
1453                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1454         }
1455
1456         for (i = 0; i < use_strategies_nr; i++) {
1457                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
1458                         fast_forward = FF_NO;
1459                 if (use_strategies[i]->attr & NO_TRIVIAL)
1460                         allow_trivial = 0;
1461         }
1462
1463         if (!remoteheads)
1464                 ; /* already up-to-date */
1465         else if (!remoteheads->next)
1466                 common = get_merge_bases(head_commit, remoteheads->item);
1467         else {
1468                 struct commit_list *list = remoteheads;
1469                 commit_list_insert(head_commit, &list);
1470                 common = get_octopus_merge_bases(list);
1471                 free(list);
1472         }
1473
1474         update_ref("updating ORIG_HEAD", "ORIG_HEAD",
1475                    &head_commit->object.oid, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
1476
1477         if (remoteheads && !common) {
1478                 /* No common ancestors found. */
1479                 if (!allow_unrelated_histories)
1480                         die(_("refusing to merge unrelated histories"));
1481                 /* otherwise, we need a real merge. */
1482         } else if (!remoteheads ||
1483                  (!remoteheads->next && !common->next &&
1484                   common->item == remoteheads->item)) {
1485                 /*
1486                  * If head can reach all the merge then we are up to date.
1487                  * but first the most common case of merging one remote.
1488                  */
1489                 finish_up_to_date(_("Already up to date."));
1490                 goto done;
1491         } else if (fast_forward != FF_NO && !remoteheads->next &&
1492                         !common->next &&
1493                         oideq(&common->item->object.oid, &head_commit->object.oid)) {
1494                 /* Again the most common case of merging one remote. */
1495                 struct strbuf msg = STRBUF_INIT;
1496                 struct commit *commit;
1497
1498                 if (verbosity >= 0) {
1499                         printf(_("Updating %s..%s\n"),
1500                                find_unique_abbrev(&head_commit->object.oid,
1501                                                   DEFAULT_ABBREV),
1502                                find_unique_abbrev(&remoteheads->item->object.oid,
1503                                                   DEFAULT_ABBREV));
1504                 }
1505                 strbuf_addstr(&msg, "Fast-forward");
1506                 if (have_message)
1507                         strbuf_addstr(&msg,
1508                                 " (no commit created; -m option ignored)");
1509                 commit = remoteheads->item;
1510                 if (!commit) {
1511                         ret = 1;
1512                         goto done;
1513                 }
1514
1515                 if (checkout_fast_forward(the_repository,
1516                                           &head_commit->object.oid,
1517                                           &commit->object.oid,
1518                                           overwrite_ignore)) {
1519                         ret = 1;
1520                         goto done;
1521                 }
1522
1523                 finish(head_commit, remoteheads, &commit->object.oid, msg.buf);
1524                 remove_merge_branch_state(the_repository);
1525                 goto done;
1526         } else if (!remoteheads->next && common->next)
1527                 ;
1528                 /*
1529                  * We are not doing octopus and not fast-forward.  Need
1530                  * a real merge.
1531                  */
1532         else if (!remoteheads->next && !common->next && option_commit) {
1533                 /*
1534                  * We are not doing octopus, not fast-forward, and have
1535                  * only one common.
1536                  */
1537                 refresh_cache(REFRESH_QUIET);
1538                 if (allow_trivial && fast_forward != FF_ONLY) {
1539                         /* See if it is really trivial. */
1540                         git_committer_info(IDENT_STRICT);
1541                         printf(_("Trying really trivial in-index merge...\n"));
1542                         if (!read_tree_trivial(&common->item->object.oid,
1543                                                &head_commit->object.oid,
1544                                                &remoteheads->item->object.oid)) {
1545                                 ret = merge_trivial(head_commit, remoteheads);
1546                                 goto done;
1547                         }
1548                         printf(_("Nope.\n"));
1549                 }
1550         } else {
1551                 /*
1552                  * An octopus.  If we can reach all the remote we are up
1553                  * to date.
1554                  */
1555                 int up_to_date = 1;
1556                 struct commit_list *j;
1557
1558                 for (j = remoteheads; j; j = j->next) {
1559                         struct commit_list *common_one;
1560
1561                         /*
1562                          * Here we *have* to calculate the individual
1563                          * merge_bases again, otherwise "git merge HEAD^
1564                          * HEAD^^" would be missed.
1565                          */
1566                         common_one = get_merge_bases(head_commit, j->item);
1567                         if (!oideq(&common_one->item->object.oid, &j->item->object.oid)) {
1568                                 up_to_date = 0;
1569                                 break;
1570                         }
1571                 }
1572                 if (up_to_date) {
1573                         finish_up_to_date(_("Already up to date. Yeeah!"));
1574                         goto done;
1575                 }
1576         }
1577
1578         if (fast_forward == FF_ONLY)
1579                 die(_("Not possible to fast-forward, aborting."));
1580
1581         /* We are going to make a new commit. */
1582         git_committer_info(IDENT_STRICT);
1583
1584         /*
1585          * At this point, we need a real merge.  No matter what strategy
1586          * we use, it would operate on the index, possibly affecting the
1587          * working tree, and when resolved cleanly, have the desired
1588          * tree in the index -- this means that the index must be in
1589          * sync with the head commit.  The strategies are responsible
1590          * to ensure this.
1591          */
1592         if (use_strategies_nr == 1 ||
1593             /*
1594              * Stash away the local changes so that we can try more than one.
1595              */
1596             save_state(&stash))
1597                 oidclr(&stash);
1598
1599         for (i = 0; !merge_was_ok && i < use_strategies_nr; i++) {
1600                 int ret, cnt;
1601                 if (i) {
1602                         printf(_("Rewinding the tree to pristine...\n"));
1603                         restore_state(&head_commit->object.oid, &stash);
1604                 }
1605                 if (use_strategies_nr != 1)
1606                         printf(_("Trying merge strategy %s...\n"),
1607                                 use_strategies[i]->name);
1608                 /*
1609                  * Remember which strategy left the state in the working
1610                  * tree.
1611                  */
1612                 wt_strategy = use_strategies[i]->name;
1613
1614                 ret = try_merge_strategy(use_strategies[i]->name,
1615                                          common, remoteheads,
1616                                          head_commit);
1617                 /*
1618                  * The backend exits with 1 when conflicts are
1619                  * left to be resolved, with 2 when it does not
1620                  * handle the given merge at all.
1621                  */
1622                 if (ret < 2) {
1623                         if (!ret) {
1624                                 if (option_commit) {
1625                                         /* Automerge succeeded. */
1626                                         automerge_was_ok = 1;
1627                                         break;
1628                                 }
1629                                 merge_was_ok = 1;
1630                         }
1631                         cnt = evaluate_result();
1632                         if (best_cnt <= 0 || cnt <= best_cnt) {
1633                                 best_strategy = use_strategies[i]->name;
1634                                 best_cnt = cnt;
1635                         }
1636                 }
1637         }
1638
1639         /*
1640          * If we have a resulting tree, that means the strategy module
1641          * auto resolved the merge cleanly.
1642          */
1643         if (automerge_was_ok) {
1644                 ret = finish_automerge(head_commit, head_subsumed,
1645                                        common, remoteheads,
1646                                        &result_tree, wt_strategy);
1647                 goto done;
1648         }
1649
1650         /*
1651          * Pick the result from the best strategy and have the user fix
1652          * it up.
1653          */
1654         if (!best_strategy) {
1655                 restore_state(&head_commit->object.oid, &stash);
1656                 if (use_strategies_nr > 1)
1657                         fprintf(stderr,
1658                                 _("No merge strategy handled the merge.\n"));
1659                 else
1660                         fprintf(stderr, _("Merge with strategy %s failed.\n"),
1661                                 use_strategies[0]->name);
1662                 ret = 2;
1663                 goto done;
1664         } else if (best_strategy == wt_strategy)
1665                 ; /* We already have its result in the working tree. */
1666         else {
1667                 printf(_("Rewinding the tree to pristine...\n"));
1668                 restore_state(&head_commit->object.oid, &stash);
1669                 printf(_("Using the %s to prepare resolving by hand.\n"),
1670                         best_strategy);
1671                 try_merge_strategy(best_strategy, common, remoteheads,
1672                                    head_commit);
1673         }
1674
1675         if (squash)
1676                 finish(head_commit, remoteheads, NULL, NULL);
1677         else
1678                 write_merge_state(remoteheads);
1679
1680         if (merge_was_ok)
1681                 fprintf(stderr, _("Automatic merge went well; "
1682                         "stopped before committing as requested\n"));
1683         else
1684                 ret = suggest_conflicts();
1685
1686 done:
1687         free(branch_to_free);
1688         return ret;
1689 }