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                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 451                         update_ref(reflog_message.buf, "HEAD", new_head, head,
 452                                    0, UPDATE_REFS_DIE_ON_ERR);
 453                         /*
 454                          * We ignore errors in 'gc --auto', since the
 455                          * user should see them.
 456                          */
 457                         close_object_store(the_repository->objects);
 458                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 459                 }
 460         }
 461         if (new_head && show_diffstat) {
 462                 struct diff_options opts;
 463                 repo_diff_setup(the_repository, &opts);
 464                 opts.stat_width = -1; /* use full terminal width */
 465                 opts.stat_graph_width = -1; /* respect statGraphWidth config */
 466                 opts.output_format |=
 467                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 468                 opts.detect_rename = DIFF_DETECT_RENAME;
 469                 diff_setup_done(&opts);
 470                 diff_tree_oid(head, new_head, "", &opts);
 471                 diffcore_std(&opts);
 472                 diff_flush(&opts);
 473         }
 474
 475         /* Run a post-merge hook */
 476         run_hook_le(NULL, "post-merge", squash ? "1" : "0", NULL);
 477
 478         strbuf_release(&reflog_message);
 479 }
 480
 481 /* Get the name for the merge commit's message. */
 482 static void merge_name(const char *remote, struct strbuf *msg)
 483 {
 484         struct commit *remote_head;
 485         struct object_id branch_head;
 486         struct strbuf buf = STRBUF_INIT;
 487         struct strbuf bname = STRBUF_INIT;
 488         struct merge_remote_desc *desc;
 489         const char *ptr;
 490         char *found_ref;
 491         int len, early;
 492
 493         strbuf_branchname(&bname, remote, 0);
 494         remote = bname.buf;
 495
 496         oidclr(&branch_head);
 497         remote_head = get_merge_parent(remote);
 498         if (!remote_head)
 499                 die(_("'%s' does not point to a commit"), remote);
 500
 501         if (dwim_ref(remote, strlen(remote), &branch_head, &found_ref) > 0) {
 502                 if (starts_with(found_ref, "refs/heads/")) {
 503                         strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 504                                     oid_to_hex(&branch_head), remote);
 505                         goto cleanup;
 506                 }
 507                 if (starts_with(found_ref, "refs/tags/")) {
 508                         strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
 509                                     oid_to_hex(&branch_head), remote);
 510                         goto cleanup;
 511                 }
 512                 if (starts_with(found_ref, "refs/remotes/")) {
 513                         strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
 514                                     oid_to_hex(&branch_head), remote);
 515                         goto cleanup;
 516                 }
 517         }
 518
 519         /* See if remote matches <name>^^^.. or <name>~<number> */
 520         for (len = 0, ptr = remote + strlen(remote);
 521              remote < ptr && ptr[-1] == '^';
 522              ptr--)
 523                 len++;
 524         if (len)
 525                 early = 1;
 526         else {
 527                 early = 0;
 528                 ptr = strrchr(remote, '~');
 529                 if (ptr) {
 530                         int seen_nonzero = 0;
 531
 532                         len++; /* count ~ */
 533                         while (*++ptr && isdigit(*ptr)) {
 534                                 seen_nonzero |= (*ptr != '0');
 535                                 len++;
 536                         }
 537                         if (*ptr)
 538                                 len = 0; /* not ...~<number> */
 539                         else if (seen_nonzero)
 540                                 early = 1;
 541                         else if (len == 1)
 542                                 early = 1; /* "name~" is "name~1"! */
 543                 }
 544         }
 545         if (len) {
 546                 struct strbuf truname = STRBUF_INIT;
 547                 strbuf_addf(&truname, "refs/heads/%s", remote);
 548                 strbuf_setlen(&truname, truname.len - len);
 549                 if (ref_exists(truname.buf)) {
 550                         strbuf_addf(msg,
 551                                     "%s\t\tbranch '%s'%s of .\n",
 552                                     oid_to_hex(&remote_head->object.oid),
 553                                     truname.buf + 11,
 554                                     (early ? " (early part)" : ""));
 555                         strbuf_release(&truname);
 556                         goto cleanup;
 557                 }
 558                 strbuf_release(&truname);
 559         }
 560
 561         desc = merge_remote_util(remote_head);
 562         if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
 563                 strbuf_addf(msg, "%s\t\t%s '%s'\n",
 564                             oid_to_hex(&desc->obj->oid),
 565                             type_name(desc->obj->type),
 566                             remote);
 567                 goto cleanup;
 568         }
 569
 570         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 571                 oid_to_hex(&remote_head->object.oid), remote);
 572 cleanup:
 573         strbuf_release(&buf);
 574         strbuf_release(&bname);
 575 }
 576
 577 static void parse_branch_merge_options(char *bmo)
 578 {
 579         const char **argv;
 580         int argc;
 581
 582         if (!bmo)
 583                 return;
 584         argc = split_cmdline(bmo, &argv);
 585         if (argc < 0)
 586                 die(_("Bad branch.%s.mergeoptions string: %s"), branch,
 587                     _(split_cmdline_strerror(argc)));
 588         REALLOC_ARRAY(argv, argc + 2);
 589         MOVE_ARRAY(argv + 1, argv, argc + 1);
 590         argc++;
 591         argv[0] = "branch.*.mergeoptions";
 592         parse_options(argc, argv, NULL, builtin_merge_options,
 593                       builtin_merge_usage, 0);
 594         free(argv);
 595 }
 596
 597 static int git_merge_config(const char *k, const char *v, void *cb)
 598 {
 599         int status;
 600         const char *str;
 601
 602         if (branch &&
 603             skip_prefix(k, "branch.", &str) &&
 604             skip_prefix(str, branch, &str) &&
 605             !strcmp(str, ".mergeoptions")) {
 606                 free(branch_mergeoptions);
 607                 branch_mergeoptions = xstrdup(v);
 608                 return 0;
 609         }
 610
 611         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 612                 show_diffstat = git_config_bool(k, v);
 613         else if (!strcmp(k, "merge.verifysignatures"))
 614                 verify_signatures = git_config_bool(k, v);
 615         else if (!strcmp(k, "pull.twohead"))
 616                 return git_config_string(&pull_twohead, k, v);
 617         else if (!strcmp(k, "pull.octopus"))
 618                 return git_config_string(&pull_octopus, k, v);
 619         else if (!strcmp(k, "commit.cleanup"))
 620                 return git_config_string(&cleanup_arg, k, v);
 621         else if (!strcmp(k, "merge.renormalize"))
 622                 option_renormalize = git_config_bool(k, v);
 623         else if (!strcmp(k, "merge.ff")) {
 624                 int boolval = git_parse_maybe_bool(v);
 625                 if (0 <= boolval) {
 626                         fast_forward = boolval ? FF_ALLOW : FF_NO;
 627                 } else if (v && !strcmp(v, "only")) {
 628                         fast_forward = FF_ONLY;
 629                 } /* do not barf on values from future versions of git */
 630                 return 0;
 631         } else if (!strcmp(k, "merge.defaulttoupstream")) {
 632                 default_to_upstream = git_config_bool(k, v);
 633                 return 0;
 634         } else if (!strcmp(k, "commit.gpgsign")) {
 635                 sign_commit = git_config_bool(k, v) ? "" : NULL;
 636                 return 0;
 637         } else if (!strcmp(k, "gpg.mintrustlevel")) {
 638                 check_trust_level = 0;
 639         }
 640
 641         status = fmt_merge_msg_config(k, v, cb);
 642         if (status)
 643                 return status;
 644         status = git_gpg_config(k, v, NULL);
 645         if (status)
 646                 return status;
 647         return git_diff_ui_config(k, v, cb);
 648 }
 649
 650 static int read_tree_trivial(struct object_id *common, struct object_id *head,
 651                              struct object_id *one)
 652 {
 653         int i, nr_trees = 0;
 654         struct tree *trees[MAX_UNPACK_TREES];
 655         struct tree_desc t[MAX_UNPACK_TREES];
 656         struct unpack_trees_options opts;
 657
 658         memset(&opts, 0, sizeof(opts));
 659         opts.head_idx = 2;
 660         opts.src_index = &the_index;
 661         opts.dst_index = &the_index;
 662         opts.update = 1;
 663         opts.verbose_update = 1;
 664         opts.trivial_merges_only = 1;
 665         opts.merge = 1;
 666         trees[nr_trees] = parse_tree_indirect(common);
 667         if (!trees[nr_trees++])
 668                 return -1;
 669         trees[nr_trees] = parse_tree_indirect(head);
 670         if (!trees[nr_trees++])
 671                 return -1;
 672         trees[nr_trees] = parse_tree_indirect(one);
 673         if (!trees[nr_trees++])
 674                 return -1;
 675         opts.fn = threeway_merge;
 676         cache_tree_free(&active_cache_tree);
 677         for (i = 0; i < nr_trees; i++) {
 678                 parse_tree(trees[i]);
 679                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 680         }
 681         if (unpack_trees(nr_trees, t, &opts))
 682                 return -1;
 683         return 0;
 684 }
 685
 686 static void write_tree_trivial(struct object_id *oid)
 687 {
 688         if (write_cache_as_tree(oid, 0, NULL))
 689                 die(_("git write-tree failed to write a tree"));
 690 }
 691
 692 static int try_merge_strategy(const char *strategy, struct commit_list *common,
 693                               struct commit_list *remoteheads,
 694                               struct commit *head)
 695 {
 696         const char *head_arg = "HEAD";
 697
 698         if (refresh_and_write_cache(REFRESH_QUIET, SKIP_IF_UNCHANGED, 0) < 0)
 699                 return error(_("Unable to write index."));
 700
 701         if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
 702                 struct lock_file lock = LOCK_INIT;
 703                 int clean, x;
 704                 struct commit *result;
 705                 struct commit_list *reversed = NULL;
 706                 struct merge_options o;
 707                 struct commit_list *j;
 708
 709                 if (remoteheads->next) {
 710                         error(_("Not handling anything other than two heads merge."));
 711                         return 2;
 712                 }
 713
 714                 init_merge_options(&o, the_repository);
 715                 if (!strcmp(strategy, "subtree"))
 716                         o.subtree_shift = "";
 717
 718                 o.renormalize = option_renormalize;
 719                 o.show_rename_progress =
 720                         show_progress == -1 ? isatty(2) : show_progress;
 721
 722                 for (x = 0; x < xopts_nr; x++)
 723                         if (parse_merge_opt(&o, xopts[x]))
 724                                 die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
 725
 726                 o.branch1 = head_arg;
 727                 o.branch2 = merge_remote_util(remoteheads->item)->name;
 728
 729                 for (j = common; j; j = j->next)
 730                         commit_list_insert(j->item, &reversed);
 731
 732                 hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
 733                 clean = merge_recursive(&o, head,
 734                                 remoteheads->item, reversed, &result);
 735                 if (clean < 0)
 736                         exit(128);
 737                 if (write_locked_index(&the_index, &lock,
 738                                        COMMIT_LOCK | SKIP_IF_UNCHANGED))
 739                         die(_("unable to write %s"), get_index_file());
 740                 return clean ? 0 : 1;
 741         } else {
 742                 return try_merge_command(the_repository,
 743                                          strategy, xopts_nr, xopts,
 744                                          common, head_arg, remoteheads);
 745         }
 746 }
 747
 748 static void count_diff_files(struct diff_queue_struct *q,
 749                              struct diff_options *opt, void *data)
 750 {
 751         int *count = data;
 752
 753         (*count) += q->nr;
 754 }
 755
 756 static int count_unmerged_entries(void)
 757 {
 758         int i, ret = 0;
 759
 760         for (i = 0; i < active_nr; i++)
 761                 if (ce_stage(active_cache[i]))
 762                         ret++;
 763
 764         return ret;
 765 }
 766
 767 static void add_strategies(const char *string, unsigned attr)
 768 {
 769         int i;
 770
 771         if (string) {
 772                 struct string_list list = STRING_LIST_INIT_DUP;
 773                 struct string_list_item *item;
 774                 string_list_split(&list, string, ' ', -1);
 775                 for_each_string_list_item(item, &list)
 776                         append_strategy(get_strategy(item->string));
 777                 string_list_clear(&list, 0);
 778                 return;
 779         }
 780         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 781                 if (all_strategy[i].attr & attr)
 782                         append_strategy(&all_strategy[i]);
 783
 784 }
 785
 786 static void read_merge_msg(struct strbuf *msg)
 787 {
 788         const char *filename = git_path_merge_msg(the_repository);
 789         strbuf_reset(msg);
 790         if (strbuf_read_file(msg, filename, 0) < 0)
 791                 die_errno(_("Could not read from '%s'"), filename);
 792 }
 793
 794 static void write_merge_state(struct commit_list *);
 795 static void abort_commit(struct commit_list *remoteheads, const char *err_msg)
 796 {
 797         if (err_msg)
 798                 error("%s", err_msg);
 799         fprintf(stderr,
 800                 _("Not committing merge; use 'git commit' to complete the merge.\n"));
 801         write_merge_state(remoteheads);
 802         exit(1);
 803 }
 804
 805 static const char merge_editor_comment[] =
 806 N_("Please enter a commit message to explain why this merge is necessary,\n"
 807    "especially if it merges an updated upstream into a topic branch.\n"
 808    "\n");
 809
 810 static const char scissors_editor_comment[] =
 811 N_("An empty message aborts the commit.\n");
 812
 813 static const char no_scissors_editor_comment[] =
 814 N_("Lines starting with '%c' will be ignored, and an empty message aborts\n"
 815    "the commit.\n");
 816
 817 static void write_merge_heads(struct commit_list *);
 818 static void prepare_to_commit(struct commit_list *remoteheads)
 819 {
 820         struct strbuf msg = STRBUF_INIT;
 821         const char *index_file = get_index_file();
 822
 823         if (!no_verify && run_commit_hook(0 < option_edit, index_file, "pre-merge-commit", NULL))
 824                 abort_commit(remoteheads, NULL);
 825         /*
 826          * Re-read the index as pre-merge-commit hook could have updated it,
 827          * and write it out as a tree.  We must do this before we invoke
 828          * the editor and after we invoke run_status above.
 829          */
 830         if (find_hook("pre-merge-commit"))
 831                 discard_cache();
 832         read_cache_from(index_file);
 833         strbuf_addbuf(&msg, &merge_msg);
 834         if (squash)
 835                 BUG("the control must not reach here under --squash");
 836         if (0 < option_edit) {
 837                 strbuf_addch(&msg, '\n');
 838                 if (cleanup_mode == COMMIT_MSG_CLEANUP_SCISSORS) {
 839                         wt_status_append_cut_line(&msg);
 840                         strbuf_commented_addf(&msg, "\n");
 841                 }
 842                 strbuf_commented_addf(&msg, _(merge_editor_comment));
 843                 strbuf_commented_addf(&msg, _(cleanup_mode == COMMIT_MSG_CLEANUP_SCISSORS ?
 844                         scissors_editor_comment :
 845                         no_scissors_editor_comment), comment_line_char);
 846         }
 847         if (signoff)
 848                 append_signoff(&msg, ignore_non_trailer(msg.buf, msg.len), 0);
 849         write_merge_heads(remoteheads);
 850         write_file_buf(git_path_merge_msg(the_repository), msg.buf, msg.len);
 851         if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
 852                             git_path_merge_msg(the_repository), "merge", NULL))
 853                 abort_commit(remoteheads, NULL);
 854         if (0 < option_edit) {
 855                 if (launch_editor(git_path_merge_msg(the_repository), NULL, NULL))
 856                         abort_commit(remoteheads, NULL);
 857         }
 858
 859         if (!no_verify && run_commit_hook(0 < option_edit, get_index_file(),
 860                                           "commit-msg",
 861                                           git_path_merge_msg(the_repository), NULL))
 862                 abort_commit(remoteheads, NULL);
 863
 864         read_merge_msg(&msg);
 865         cleanup_message(&msg, cleanup_mode, 0);
 866         if (!msg.len)
 867                 abort_commit(remoteheads, _("Empty commit message."));
 868         strbuf_release(&merge_msg);
 869         strbuf_addbuf(&merge_msg, &msg);
 870         strbuf_release(&msg);
 871 }
 872
 873 static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
 874 {
 875         struct object_id result_tree, result_commit;
 876         struct commit_list *parents, **pptr = &parents;
 877
 878         if (refresh_and_write_cache(REFRESH_QUIET, SKIP_IF_UNCHANGED, 0) < 0)
 879                 return error(_("Unable to write index."));
 880
 881         write_tree_trivial(&result_tree);
 882         printf(_("Wonderful.\n"));
 883         pptr = commit_list_append(head, pptr);
 884         pptr = commit_list_append(remoteheads->item, pptr);
 885         prepare_to_commit(remoteheads);
 886         if (commit_tree(merge_msg.buf, merge_msg.len, &result_tree, parents,
 887                         &result_commit, NULL, sign_commit))
 888                 die(_("failed to write commit object"));
 889         finish(head, remoteheads, &result_commit, "In-index merge");
 890         remove_merge_branch_state(the_repository);
 891         return 0;
 892 }
 893
 894 static int finish_automerge(struct commit *head,
 895                             int head_subsumed,
 896                             struct commit_list *common,
 897                             struct commit_list *remoteheads,
 898                             struct object_id *result_tree,
 899                             const char *wt_strategy)
 900 {
 901         struct commit_list *parents = NULL;
 902         struct strbuf buf = STRBUF_INIT;
 903         struct object_id result_commit;
 904
 905         write_tree_trivial(result_tree);
 906         free_commit_list(common);
 907         parents = remoteheads;
 908         if (!head_subsumed || fast_forward == FF_NO)
 909                 commit_list_insert(head, &parents);
 910         prepare_to_commit(remoteheads);
 911         if (commit_tree(merge_msg.buf, merge_msg.len, result_tree, parents,
 912                         &result_commit, NULL, sign_commit))
 913                 die(_("failed to write commit object"));
 914         strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
 915         finish(head, remoteheads, &result_commit, buf.buf);
 916         strbuf_release(&buf);
 917         remove_merge_branch_state(the_repository);
 918         return 0;
 919 }
 920
 921 static int suggest_conflicts(void)
 922 {
 923         const char *filename;
 924         FILE *fp;
 925         struct strbuf msgbuf = STRBUF_INIT;
 926
 927         filename = git_path_merge_msg(the_repository);
 928         fp = xfopen(filename, "a");
 929
 930         /*
 931          * We can't use cleanup_mode because if we're not using the editor,
 932          * get_cleanup_mode will return COMMIT_MSG_CLEANUP_SPACE instead, even
 933          * though the message is meant to be processed later by git-commit.
 934          * Thus, we will get the cleanup mode which is returned when we _are_
 935          * using an editor.
 936          */
 937         append_conflicts_hint(&the_index, &msgbuf,
 938                               get_cleanup_mode(cleanup_arg, 1));
 939         fputs(msgbuf.buf, fp);
 940         strbuf_release(&msgbuf);
 941         fclose(fp);
 942         repo_rerere(the_repository, allow_rerere_auto);
 943         printf(_("Automatic merge failed; "
 944                         "fix conflicts and then commit the result.\n"));
 945         return 1;
 946 }
 947
 948 static int evaluate_result(void)
 949 {
 950         int cnt = 0;
 951         struct rev_info rev;
 952
 953         /* Check how many files differ. */
 954         repo_init_revisions(the_repository, &rev, "");
 955         setup_revisions(0, NULL, &rev, NULL);
 956         rev.diffopt.output_format |=
 957                 DIFF_FORMAT_CALLBACK;
 958         rev.diffopt.format_callback = count_diff_files;
 959         rev.diffopt.format_callback_data = &cnt;
 960         run_diff_files(&rev, 0);
 961
 962         /*
 963          * Check how many unmerged entries are
 964          * there.
 965          */
 966         cnt += count_unmerged_entries();
 967
 968         return cnt;
 969 }
 970
 971 /*
 972  * Pretend as if the user told us to merge with the remote-tracking
 973  * branch we have for the upstream of the current branch
 974  */
 975 static int setup_with_upstream(const char ***argv)
 976 {
 977         struct branch *branch = branch_get(NULL);
 978         int i;
 979         const char **args;
 980
 981         if (!branch)
 982                 die(_("No current branch."));
 983         if (!branch->remote_name)
 984                 die(_("No remote for the current branch."));
 985         if (!branch->merge_nr)
 986                 die(_("No default upstream defined for the current branch."));
 987
 988         args = xcalloc(st_add(branch->merge_nr, 1), sizeof(char *));
 989         for (i = 0; i < branch->merge_nr; i++) {
 990                 if (!branch->merge[i]->dst)
 991                         die(_("No remote-tracking branch for %s from %s"),
 992                             branch->merge[i]->src, branch->remote_name);
 993                 args[i] = branch->merge[i]->dst;
 994         }
 995         args[i] = NULL;
 996         *argv = args;
 997         return i;
 998 }
 999
1000 static void write_merge_heads(struct commit_list *remoteheads)
1001 {
1002         struct commit_list *j;
1003         struct strbuf buf = STRBUF_INIT;
1004
1005         for (j = remoteheads; j; j = j->next) {
1006                 struct object_id *oid;
1007                 struct commit *c = j->item;
1008                 struct merge_remote_desc *desc;
1009
1010                 desc = merge_remote_util(c);
1011                 if (desc && desc->obj) {
1012                         oid = &desc->obj->oid;
1013                 } else {
1014                         oid = &c->object.oid;
1015                 }
1016                 strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
1017         }
1018         write_file_buf(git_path_merge_head(the_repository), buf.buf, buf.len);
1019
1020         strbuf_reset(&buf);
1021         if (fast_forward == FF_NO)
1022                 strbuf_addstr(&buf, "no-ff");
1023         write_file_buf(git_path_merge_mode(the_repository), buf.buf, buf.len);
1024         strbuf_release(&buf);
1025 }
1026
1027 static void write_merge_state(struct commit_list *remoteheads)
1028 {
1029         write_merge_heads(remoteheads);
1030         strbuf_addch(&merge_msg, '\n');
1031         write_file_buf(git_path_merge_msg(the_repository), merge_msg.buf,
1032                        merge_msg.len);
1033 }
1034
1035 static int default_edit_option(void)
1036 {
1037         static const char name[] = "GIT_MERGE_AUTOEDIT";
1038         const char *e = getenv(name);
1039         struct stat st_stdin, st_stdout;
1040
1041         if (have_message)
1042                 /* an explicit -m msg without --[no-]edit */
1043                 return 0;
1044
1045         if (e) {
1046                 int v = git_parse_maybe_bool(e);
1047                 if (v < 0)
1048                         die(_("Bad value '%s' in environment '%s'"), e, name);
1049                 return v;
1050         }
1051
1052         /* Use editor if stdin and stdout are the same and is a tty */
1053         return (!fstat(0, &st_stdin) &&
1054                 !fstat(1, &st_stdout) &&
1055                 isatty(0) && isatty(1) &&
1056                 st_stdin.st_dev == st_stdout.st_dev &&
1057                 st_stdin.st_ino == st_stdout.st_ino &&
1058                 st_stdin.st_mode == st_stdout.st_mode);
1059 }
1060
1061 static struct commit_list *reduce_parents(struct commit *head_commit,
1062                                           int *head_subsumed,
1063                                           struct commit_list *remoteheads)
1064 {
1065         struct commit_list *parents, **remotes;
1066
1067         /*
1068          * Is the current HEAD reachable from another commit being
1069          * merged?  If so we do not want to record it as a parent of
1070          * the resulting merge, unless --no-ff is given.  We will flip
1071          * this variable to 0 when we find HEAD among the independent
1072          * tips being merged.
1073          */
1074         *head_subsumed = 1;
1075
1076         /* Find what parents to record by checking independent ones. */
1077         parents = reduce_heads(remoteheads);
1078         free_commit_list(remoteheads);
1079
1080         remoteheads = NULL;
1081         remotes = &remoteheads;
1082         while (parents) {
1083                 struct commit *commit = pop_commit(&parents);
1084                 if (commit == head_commit)
1085                         *head_subsumed = 0;
1086                 else
1087                         remotes = &commit_list_insert(commit, remotes)->next;
1088         }
1089         return remoteheads;
1090 }
1091
1092 static void prepare_merge_message(struct strbuf *merge_names, struct strbuf *merge_msg)
1093 {
1094         struct fmt_merge_msg_opts opts;
1095
1096         memset(&opts, 0, sizeof(opts));
1097         opts.add_title = !have_message;
1098         opts.shortlog_len = shortlog_len;
1099         opts.credit_people = (0 < option_edit);
1100
1101         fmt_merge_msg(merge_names, merge_msg, &opts);
1102         if (merge_msg->len)
1103                 strbuf_setlen(merge_msg, merge_msg->len - 1);
1104 }
1105
1106 static void handle_fetch_head(struct commit_list **remotes, struct strbuf *merge_names)
1107 {
1108         const char *filename;
1109         int fd, pos, npos;
1110         struct strbuf fetch_head_file = STRBUF_INIT;
1111         const unsigned hexsz = the_hash_algo->hexsz;
1112
1113         if (!merge_names)
1114                 merge_names = &fetch_head_file;
1115
1116         filename = git_path_fetch_head(the_repository);
1117         fd = open(filename, O_RDONLY);
1118         if (fd < 0)
1119                 die_errno(_("could not open '%s' for reading"), filename);
1120
1121         if (strbuf_read(merge_names, fd, 0) < 0)
1122                 die_errno(_("could not read '%s'"), filename);
1123         if (close(fd) < 0)
1124                 die_errno(_("could not close '%s'"), filename);
1125
1126         for (pos = 0; pos < merge_names->len; pos = npos) {
1127                 struct object_id oid;
1128                 char *ptr;
1129                 struct commit *commit;
1130
1131                 ptr = strchr(merge_names->buf + pos, '\n');
1132                 if (ptr)
1133                         npos = ptr - merge_names->buf + 1;
1134                 else
1135                         npos = merge_names->len;
1136
1137                 if (npos - pos < hexsz + 2 ||
1138                     get_oid_hex(merge_names->buf + pos, &oid))
1139                         commit = NULL; /* bad */
1140                 else if (memcmp(merge_names->buf + pos + hexsz, "\t\t", 2))
1141                         continue; /* not-for-merge */
1142                 else {
1143                         char saved = merge_names->buf[pos + hexsz];
1144                         merge_names->buf[pos + hexsz] = '\0';
1145                         commit = get_merge_parent(merge_names->buf + pos);
1146                         merge_names->buf[pos + hexsz] = saved;
1147                 }
1148                 if (!commit) {
1149                         if (ptr)
1150                                 *ptr = '\0';
1151                         die(_("not something we can merge in %s: %s"),
1152                             filename, merge_names->buf + pos);
1153                 }
1154                 remotes = &commit_list_insert(commit, remotes)->next;
1155         }
1156
1157         if (merge_names == &fetch_head_file)
1158                 strbuf_release(&fetch_head_file);
1159 }
1160
1161 static struct commit_list *collect_parents(struct commit *head_commit,
1162                                            int *head_subsumed,
1163                                            int argc, const char **argv,
1164                                            struct strbuf *merge_msg)
1165 {
1166         int i;
1167         struct commit_list *remoteheads = NULL;
1168         struct commit_list **remotes = &remoteheads;
1169         struct strbuf merge_names = STRBUF_INIT, *autogen = NULL;
1170
1171         if (merge_msg && (!have_message || shortlog_len))
1172                 autogen = &merge_names;
1173
1174         if (head_commit)
1175                 remotes = &commit_list_insert(head_commit, remotes)->next;
1176
1177         if (argc == 1 && !strcmp(argv[0], "FETCH_HEAD")) {
1178                 handle_fetch_head(remotes, autogen);
1179                 remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
1180         } else {
1181                 for (i = 0; i < argc; i++) {
1182                         struct commit *commit = get_merge_parent(argv[i]);
1183                         if (!commit)
1184                                 help_unknown_ref(argv[i], "merge",
1185                                                  _("not something we can merge"));
1186                         remotes = &commit_list_insert(commit, remotes)->next;
1187                 }
1188                 remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
1189                 if (autogen) {
1190                         struct commit_list *p;
1191                         for (p = remoteheads; p; p = p->next)
1192                                 merge_name(merge_remote_util(p->item)->name, autogen);
1193                 }
1194         }
1195
1196         if (autogen) {
1197                 prepare_merge_message(autogen, merge_msg);
1198                 strbuf_release(autogen);
1199         }
1200
1201         return remoteheads;
1202 }
1203
1204 static int merging_a_throwaway_tag(struct commit *commit)
1205 {
1206         char *tag_ref;
1207         struct object_id oid;
1208         int is_throwaway_tag = 0;
1209
1210         /* Are we merging a tag? */
1211         if (!merge_remote_util(commit) ||
1212             !merge_remote_util(commit)->obj ||
1213             merge_remote_util(commit)->obj->type != OBJ_TAG)
1214                 return is_throwaway_tag;
1215
1216         /*
1217          * Now we know we are merging a tag object.  Are we downstream
1218          * and following the tags from upstream?  If so, we must have
1219          * the tag object pointed at by "refs/tags/$T" where $T is the
1220          * tagname recorded in the tag object.  We want to allow such
1221          * a "just to catch up" merge to fast-forward.
1222          *
1223          * Otherwise, we are playing an integrator's role, making a
1224          * merge with a throw-away tag from a contributor with
1225          * something like "git pull $contributor $signed_tag".
1226          * We want to forbid such a merge from fast-forwarding
1227          * by default; otherwise we would not keep the signature
1228          * anywhere.
1229          */
1230         tag_ref = xstrfmt("refs/tags/%s",
1231                           ((struct tag *)merge_remote_util(commit)->obj)->tag);
1232         if (!read_ref(tag_ref, &oid) &&
1233             oideq(&oid, &merge_remote_util(commit)->obj->oid))
1234                 is_throwaway_tag = 0;
1235         else
1236                 is_throwaway_tag = 1;
1237         free(tag_ref);
1238         return is_throwaway_tag;
1239 }
1240
1241 int cmd_merge(int argc, const char **argv, const char *prefix)
1242 {
1243         struct object_id result_tree, stash, head_oid;
1244         struct commit *head_commit;
1245         struct strbuf buf = STRBUF_INIT;
1246         int i, ret = 0, head_subsumed;
1247         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
1248         struct commit_list *common = NULL;
1249         const char *best_strategy = NULL, *wt_strategy = NULL;
1250         struct commit_list *remoteheads, *p;
1251         void *branch_to_free;
1252         int orig_argc = argc;
1253
1254         if (argc == 2 && !strcmp(argv[1], "-h"))
1255                 usage_with_options(builtin_merge_usage, builtin_merge_options);
1256
1257         /*
1258          * Check if we are _not_ on a detached HEAD, i.e. if there is a
1259          * current branch.
1260          */
1261         branch = branch_to_free = resolve_refdup("HEAD", 0, &head_oid, NULL);
1262         if (branch)
1263                 skip_prefix(branch, "refs/heads/", &branch);
1264
1265         init_diff_ui_defaults();
1266         git_config(git_merge_config, NULL);
1267
1268         if (!branch || is_null_oid(&head_oid))
1269                 head_commit = NULL;
1270         else
1271                 head_commit = lookup_commit_or_die(&head_oid, "HEAD");
1272
1273         if (branch_mergeoptions)
1274                 parse_branch_merge_options(branch_mergeoptions);
1275         argc = parse_options(argc, argv, prefix, builtin_merge_options,
1276                         builtin_merge_usage, 0);
1277         if (shortlog_len < 0)
1278                 shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;
1279
1280         if (verbosity < 0 && show_progress == -1)
1281                 show_progress = 0;
1282
1283         if (abort_current_merge) {
1284                 int nargc = 2;
1285                 const char *nargv[] = {"reset", "--merge", NULL};
1286
1287                 if (orig_argc != 2)
1288                         usage_msg_opt(_("--abort expects no arguments"),
1289                               builtin_merge_usage, builtin_merge_options);
1290
1291                 if (!file_exists(git_path_merge_head(the_repository)))
1292                         die(_("There is no merge to abort (MERGE_HEAD missing)."));
1293
1294                 /* Invoke 'git reset --merge' */
1295                 ret = cmd_reset(nargc, nargv, prefix);
1296                 goto done;
1297         }
1298
1299         if (quit_current_merge) {
1300                 if (orig_argc != 2)
1301                         usage_msg_opt(_("--quit expects no arguments"),
1302                                       builtin_merge_usage,
1303                                       builtin_merge_options);
1304
1305                 remove_merge_branch_state(the_repository);
1306                 goto done;
1307         }
1308
1309         if (continue_current_merge) {
1310                 int nargc = 1;
1311                 const char *nargv[] = {"commit", NULL};
1312
1313                 if (orig_argc != 2)
1314                         usage_msg_opt(_("--continue expects no arguments"),
1315                               builtin_merge_usage, builtin_merge_options);
1316
1317                 if (!file_exists(git_path_merge_head(the_repository)))
1318                         die(_("There is no merge in progress (MERGE_HEAD missing)."));
1319
1320                 /* Invoke 'git commit' */
1321                 ret = cmd_commit(nargc, nargv, prefix);
1322                 goto done;
1323         }
1324
1325         if (read_cache_unmerged())
1326                 die_resolve_conflict("merge");
1327
1328         if (file_exists(git_path_merge_head(the_repository))) {
1329                 /*
1330                  * There is no unmerged entry, don't advise 'git
1331                  * add/rm <file>', just 'git commit'.
1332                  */
1333                 if (advice_resolve_conflict)
1334                         die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1335                                   "Please, commit your changes before you merge."));
1336                 else
1337                         die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1338         }
1339         if (file_exists(git_path_cherry_pick_head(the_repository))) {
1340                 if (advice_resolve_conflict)
1341                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1342                             "Please, commit your changes before you merge."));
1343                 else
1344                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
1345         }
1346         resolve_undo_clear();
1347
1348         if (option_edit < 0)
1349                 option_edit = default_edit_option();
1350
1351         cleanup_mode = get_cleanup_mode(cleanup_arg, 0 < option_edit);
1352
1353         if (verbosity < 0)
1354                 show_diffstat = 0;
1355
1356         if (squash) {
1357                 if (fast_forward == FF_NO)
1358                         die(_("You cannot combine --squash with --no-ff."));
1359                 if (option_commit > 0)
1360                         die(_("You cannot combine --squash with --commit."));
1361                 /*
1362                  * squash can now silently disable option_commit - this is not
1363                  * a problem as it is only overriding the default, not a user
1364                  * supplied option.
1365                  */
1366                 option_commit = 0;
1367         }
1368
1369         if (option_commit < 0)
1370                 option_commit = 1;
1371
1372         if (!argc) {
1373                 if (default_to_upstream)
1374                         argc = setup_with_upstream(&argv);
1375                 else
1376                         die(_("No commit specified and merge.defaultToUpstream not set."));
1377         } else if (argc == 1 && !strcmp(argv[0], "-")) {
1378                 argv[0] = "@{-1}";
1379         }
1380
1381         if (!argc)
1382                 usage_with_options(builtin_merge_usage,
1383                         builtin_merge_options);
1384
1385         if (!head_commit) {
1386                 /*
1387                  * If the merged head is a valid one there is no reason
1388                  * to forbid "git merge" into a branch yet to be born.
1389                  * We do the same for "git pull".
1390                  */
1391                 struct object_id *remote_head_oid;
1392                 if (squash)
1393                         die(_("Squash commit into empty head not supported yet"));
1394                 if (fast_forward == FF_NO)
1395                         die(_("Non-fast-forward commit does not make sense into "
1396                             "an empty head"));
1397                 remoteheads = collect_parents(head_commit, &head_subsumed,
1398                                               argc, argv, NULL);
1399                 if (!remoteheads)
1400                         die(_("%s - not something we can merge"), argv[0]);
1401                 if (remoteheads->next)
1402                         die(_("Can merge only exactly one commit into empty head"));
1403
1404                 if (verify_signatures)
1405                         verify_merge_signature(remoteheads->item, verbosity,
1406                                                check_trust_level);
1407
1408                 remote_head_oid = &remoteheads->item->object.oid;
1409                 read_empty(remote_head_oid, 0);
1410                 update_ref("initial pull", "HEAD", remote_head_oid, NULL, 0,
1411                            UPDATE_REFS_DIE_ON_ERR);
1412                 goto done;
1413         }
1414
1415         /*
1416          * All the rest are the commits being merged; prepare
1417          * the standard merge summary message to be appended
1418          * to the given message.
1419          */
1420         remoteheads = collect_parents(head_commit, &head_subsumed,
1421                                       argc, argv, &merge_msg);
1422
1423         if (!head_commit || !argc)
1424                 usage_with_options(builtin_merge_usage,
1425                         builtin_merge_options);
1426
1427         if (verify_signatures) {
1428                 for (p = remoteheads; p; p = p->next) {
1429                         verify_merge_signature(p->item, verbosity,
1430                                                check_trust_level);
1431                 }
1432         }
1433
1434         strbuf_addstr(&buf, "merge");
1435         for (p = remoteheads; p; p = p->next)
1436                 strbuf_addf(&buf, " %s", merge_remote_util(p->item)->name);
1437         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1438         strbuf_reset(&buf);
1439
1440         for (p = remoteheads; p; p = p->next) {
1441                 struct commit *commit = p->item;
1442                 strbuf_addf(&buf, "GITHEAD_%s",
1443                             oid_to_hex(&commit->object.oid));
1444                 setenv(buf.buf, merge_remote_util(commit)->name, 1);
1445                 strbuf_reset(&buf);
1446                 if (fast_forward != FF_ONLY && merging_a_throwaway_tag(commit))
1447                         fast_forward = FF_NO;
1448         }
1449
1450         if (!use_strategies) {
1451                 if (!remoteheads)
1452                         ; /* already up-to-date */
1453                 else if (!remoteheads->next)
1454                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1455                 else
1456                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1457         }
1458
1459         for (i = 0; i < use_strategies_nr; i++) {
1460                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
1461                         fast_forward = FF_NO;
1462                 if (use_strategies[i]->attr & NO_TRIVIAL)
1463                         allow_trivial = 0;
1464         }
1465
1466         if (!remoteheads)
1467                 ; /* already up-to-date */
1468         else if (!remoteheads->next)
1469                 common = get_merge_bases(head_commit, remoteheads->item);
1470         else {
1471                 struct commit_list *list = remoteheads;
1472                 commit_list_insert(head_commit, &list);
1473                 common = get_octopus_merge_bases(list);
1474                 free(list);
1475         }
1476
1477         update_ref("updating ORIG_HEAD", "ORIG_HEAD",
1478                    &head_commit->object.oid, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
1479
1480         if (remoteheads && !common) {
1481                 /* No common ancestors found. */
1482                 if (!allow_unrelated_histories)
1483                         die(_("refusing to merge unrelated histories"));
1484                 /* otherwise, we need a real merge. */
1485         } else if (!remoteheads ||
1486                  (!remoteheads->next && !common->next &&
1487                   common->item == remoteheads->item)) {
1488                 /*
1489                  * If head can reach all the merge then we are up to date.
1490                  * but first the most common case of merging one remote.
1491                  */
1492                 finish_up_to_date(_("Already up to date."));
1493                 goto done;
1494         } else if (fast_forward != FF_NO && !remoteheads->next &&
1495                         !common->next &&
1496                         oideq(&common->item->object.oid, &head_commit->object.oid)) {
1497                 /* Again the most common case of merging one remote. */
1498                 struct strbuf msg = STRBUF_INIT;
1499                 struct commit *commit;
1500
1501                 if (verbosity >= 0) {
1502                         printf(_("Updating %s..%s\n"),
1503                                find_unique_abbrev(&head_commit->object.oid,
1504                                                   DEFAULT_ABBREV),
1505                                find_unique_abbrev(&remoteheads->item->object.oid,
1506                                                   DEFAULT_ABBREV));
1507                 }
1508                 strbuf_addstr(&msg, "Fast-forward");
1509                 if (have_message)
1510                         strbuf_addstr(&msg,
1511                                 " (no commit created; -m option ignored)");
1512                 commit = remoteheads->item;
1513                 if (!commit) {
1514                         ret = 1;
1515                         goto done;
1516                 }
1517
1518                 if (checkout_fast_forward(the_repository,
1519                                           &head_commit->object.oid,
1520                                           &commit->object.oid,
1521                                           overwrite_ignore)) {
1522                         ret = 1;
1523                         goto done;
1524                 }
1525
1526                 finish(head_commit, remoteheads, &commit->object.oid, msg.buf);
1527                 remove_merge_branch_state(the_repository);
1528                 goto done;
1529         } else if (!remoteheads->next && common->next)
1530                 ;
1531                 /*
1532                  * We are not doing octopus and not fast-forward.  Need
1533                  * a real merge.
1534                  */
1535         else if (!remoteheads->next && !common->next && option_commit) {
1536                 /*
1537                  * We are not doing octopus, not fast-forward, and have
1538                  * only one common.
1539                  */
1540                 refresh_cache(REFRESH_QUIET);
1541                 if (allow_trivial && fast_forward != FF_ONLY) {
1542                         /* See if it is really trivial. */
1543                         git_committer_info(IDENT_STRICT);
1544                         printf(_("Trying really trivial in-index merge...\n"));
1545                         if (!read_tree_trivial(&common->item->object.oid,
1546                                                &head_commit->object.oid,
1547                                                &remoteheads->item->object.oid)) {
1548                                 ret = merge_trivial(head_commit, remoteheads);
1549                                 goto done;
1550                         }
1551                         printf(_("Nope.\n"));
1552                 }
1553         } else {
1554                 /*
1555                  * An octopus.  If we can reach all the remote we are up
1556                  * to date.
1557                  */
1558                 int up_to_date = 1;
1559                 struct commit_list *j;
1560
1561                 for (j = remoteheads; j; j = j->next) {
1562                         struct commit_list *common_one;
1563
1564                         /*
1565                          * Here we *have* to calculate the individual
1566                          * merge_bases again, otherwise "git merge HEAD^
1567                          * HEAD^^" would be missed.
1568                          */
1569                         common_one = get_merge_bases(head_commit, j->item);
1570                         if (!oideq(&common_one->item->object.oid, &j->item->object.oid)) {
1571                                 up_to_date = 0;
1572                                 break;
1573                         }
1574                 }
1575                 if (up_to_date) {
1576                         finish_up_to_date(_("Already up to date. Yeeah!"));
1577                         goto done;
1578                 }
1579         }
1580
1581         if (fast_forward == FF_ONLY)
1582                 die(_("Not possible to fast-forward, aborting."));
1583
1584         /* We are going to make a new commit. */
1585         git_committer_info(IDENT_STRICT);
1586
1587         /*
1588          * At this point, we need a real merge.  No matter what strategy
1589          * we use, it would operate on the index, possibly affecting the
1590          * working tree, and when resolved cleanly, have the desired
1591          * tree in the index -- this means that the index must be in
1592          * sync with the head commit.  The strategies are responsible
1593          * to ensure this.
1594          */
1595         if (use_strategies_nr == 1 ||
1596             /*
1597              * Stash away the local changes so that we can try more than one.
1598              */
1599             save_state(&stash))
1600                 oidclr(&stash);
1601
1602         for (i = 0; !merge_was_ok && i < use_strategies_nr; i++) {
1603                 int ret, cnt;
1604                 if (i) {
1605                         printf(_("Rewinding the tree to pristine...\n"));
1606                         restore_state(&head_commit->object.oid, &stash);
1607                 }
1608                 if (use_strategies_nr != 1)
1609                         printf(_("Trying merge strategy %s...\n"),
1610                                 use_strategies[i]->name);
1611                 /*
1612                  * Remember which strategy left the state in the working
1613                  * tree.
1614                  */
1615                 wt_strategy = use_strategies[i]->name;
1616
1617                 ret = try_merge_strategy(use_strategies[i]->name,
1618                                          common, remoteheads,
1619                                          head_commit);
1620                 /*
1621                  * The backend exits with 1 when conflicts are
1622                  * left to be resolved, with 2 when it does not
1623                  * handle the given merge at all.
1624                  */
1625                 if (ret < 2) {
1626                         if (!ret) {
1627                                 if (option_commit) {
1628                                         /* Automerge succeeded. */
1629                                         automerge_was_ok = 1;
1630                                         break;
1631                                 }
1632                                 merge_was_ok = 1;
1633                         }
1634                         cnt = evaluate_result();
1635                         if (best_cnt <= 0 || cnt <= best_cnt) {
1636                                 best_strategy = use_strategies[i]->name;
1637                                 best_cnt = cnt;
1638                         }
1639                 }
1640         }
1641
1642         /*
1643          * If we have a resulting tree, that means the strategy module
1644          * auto resolved the merge cleanly.
1645          */
1646         if (automerge_was_ok) {
1647                 ret = finish_automerge(head_commit, head_subsumed,
1648                                        common, remoteheads,
1649                                        &result_tree, wt_strategy);
1650                 goto done;
1651         }
1652
1653         /*
1654          * Pick the result from the best strategy and have the user fix
1655          * it up.
1656          */
1657         if (!best_strategy) {
1658                 restore_state(&head_commit->object.oid, &stash);
1659                 if (use_strategies_nr > 1)
1660                         fprintf(stderr,
1661                                 _("No merge strategy handled the merge.\n"));
1662                 else
1663                         fprintf(stderr, _("Merge with strategy %s failed.\n"),
1664                                 use_strategies[0]->name);
1665                 ret = 2;
1666                 goto done;
1667         } else if (best_strategy == wt_strategy)
1668                 ; /* We already have its result in the working tree. */
1669         else {
1670                 printf(_("Rewinding the tree to pristine...\n"));
1671                 restore_state(&head_commit->object.oid, &stash);
1672                 printf(_("Using the %s to prepare resolving by hand.\n"),
1673                         best_strategy);
1674                 try_merge_strategy(best_strategy, common, remoteheads,
1675                                    head_commit);
1676         }
1677
1678         if (squash)
1679                 finish(head_commit, remoteheads, NULL, NULL);
1680         else
1681                 write_merge_state(remoteheads);
1682
1683         if (merge_was_ok)
1684                 fprintf(stderr, _("Automatic merge went well; "
1685                         "stopped before committing as requested\n"));
1686         else
1687                 ret = suggest_conflicts();
1688
1689 done:
1690         free(branch_to_free);
1691         return ret;
1692 }