builtin / merge.con commit Merge branch 'cc/replace-with-the-same-type' (80f165a)
   1/*
   2 * Builtin "git merge"
   3 *
   4 * Copyright (c) 2008 Miklos Vajna <vmiklos@frugalware.org>
   5 *
   6 * Based on git-merge.sh by Junio C Hamano.
   7 */
   8
   9#include "cache.h"
  10#include "parse-options.h"
  11#include "builtin.h"
  12#include "run-command.h"
  13#include "diff.h"
  14#include "refs.h"
  15#include "commit.h"
  16#include "diffcore.h"
  17#include "revision.h"
  18#include "unpack-trees.h"
  19#include "cache-tree.h"
  20#include "dir.h"
  21#include "utf8.h"
  22#include "log-tree.h"
  23#include "color.h"
  24#include "rerere.h"
  25#include "help.h"
  26#include "merge-recursive.h"
  27#include "resolve-undo.h"
  28#include "remote.h"
  29#include "fmt-merge-msg.h"
  30#include "gpg-interface.h"
  31
  32#define DEFAULT_TWOHEAD (1<<0)
  33#define DEFAULT_OCTOPUS (1<<1)
  34#define NO_FAST_FORWARD (1<<2)
  35#define NO_TRIVIAL      (1<<3)
  36
  37struct strategy {
  38        const char *name;
  39        unsigned attr;
  40};
  41
  42static const char * const builtin_merge_usage[] = {
  43        N_("git merge [options] [<commit>...]"),
  44        N_("git merge [options] <msg> HEAD <commit>"),
  45        N_("git merge --abort"),
  46        NULL
  47};
  48
  49static int show_diffstat = 1, shortlog_len = -1, squash;
  50static int option_commit = 1;
  51static int option_edit = -1;
  52static int allow_trivial = 1, have_message, verify_signatures;
  53static int overwrite_ignore = 1;
  54static struct strbuf merge_msg = STRBUF_INIT;
  55static struct strategy **use_strategies;
  56static size_t use_strategies_nr, use_strategies_alloc;
  57static const char **xopts;
  58static size_t xopts_nr, xopts_alloc;
  59static const char *branch;
  60static char *branch_mergeoptions;
  61static int option_renormalize;
  62static int verbosity;
  63static int allow_rerere_auto;
  64static int abort_current_merge;
  65static int show_progress = -1;
  66static int default_to_upstream;
  67static const char *sign_commit;
  68
  69static struct strategy all_strategy[] = {
  70        { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
  71        { "octopus",    DEFAULT_OCTOPUS },
  72        { "resolve",    0 },
  73        { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
  74        { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
  75};
  76
  77static const char *pull_twohead, *pull_octopus;
  78
  79enum ff_type {
  80        FF_NO,
  81        FF_ALLOW,
  82        FF_ONLY
  83};
  84
  85static enum ff_type fast_forward = FF_ALLOW;
  86
  87static int option_parse_message(const struct option *opt,
  88                                const char *arg, int unset)
  89{
  90        struct strbuf *buf = opt->value;
  91
  92        if (unset)
  93                strbuf_setlen(buf, 0);
  94        else if (arg) {
  95                strbuf_addf(buf, "%s%s", buf->len ? "\n\n" : "", arg);
  96                have_message = 1;
  97        } else
  98                return error(_("switch `m' requires a value"));
  99        return 0;
 100}
 101
 102static struct strategy *get_strategy(const char *name)
 103{
 104        int i;
 105        struct strategy *ret;
 106        static struct cmdnames main_cmds, other_cmds;
 107        static int loaded;
 108
 109        if (!name)
 110                return NULL;
 111
 112        for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 113                if (!strcmp(name, all_strategy[i].name))
 114                        return &all_strategy[i];
 115
 116        if (!loaded) {
 117                struct cmdnames not_strategies;
 118                loaded = 1;
 119
 120                memset(&not_strategies, 0, sizeof(struct cmdnames));
 121                load_command_list("git-merge-", &main_cmds, &other_cmds);
 122                for (i = 0; i < main_cmds.cnt; i++) {
 123                        int j, found = 0;
 124                        struct cmdname *ent = main_cmds.names[i];
 125                        for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
 126                                if (!strncmp(ent->name, all_strategy[j].name, ent->len)
 127                                                && !all_strategy[j].name[ent->len])
 128                                        found = 1;
 129                        if (!found)
 130                                add_cmdname(&not_strategies, ent->name, ent->len);
 131                }
 132                exclude_cmds(&main_cmds, &not_strategies);
 133        }
 134        if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
 135                fprintf(stderr, _("Could not find merge strategy '%s'.\n"), name);
 136                fprintf(stderr, _("Available strategies are:"));
 137                for (i = 0; i < main_cmds.cnt; i++)
 138                        fprintf(stderr, " %s", main_cmds.names[i]->name);
 139                fprintf(stderr, ".\n");
 140                if (other_cmds.cnt) {
 141                        fprintf(stderr, _("Available custom strategies are:"));
 142                        for (i = 0; i < other_cmds.cnt; i++)
 143                                fprintf(stderr, " %s", other_cmds.names[i]->name);
 144                        fprintf(stderr, ".\n");
 145                }
 146                exit(1);
 147        }
 148
 149        ret = xcalloc(1, sizeof(struct strategy));
 150        ret->name = xstrdup(name);
 151        ret->attr = NO_TRIVIAL;
 152        return ret;
 153}
 154
 155static void append_strategy(struct strategy *s)
 156{
 157        ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
 158        use_strategies[use_strategies_nr++] = s;
 159}
 160
 161static int option_parse_strategy(const struct option *opt,
 162                                 const char *name, int unset)
 163{
 164        if (unset)
 165                return 0;
 166
 167        append_strategy(get_strategy(name));
 168        return 0;
 169}
 170
 171static int option_parse_x(const struct option *opt,
 172                          const char *arg, int unset)
 173{
 174        if (unset)
 175                return 0;
 176
 177        ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
 178        xopts[xopts_nr++] = xstrdup(arg);
 179        return 0;
 180}
 181
 182static int option_parse_n(const struct option *opt,
 183                          const char *arg, int unset)
 184{
 185        show_diffstat = unset;
 186        return 0;
 187}
 188
 189static int option_parse_ff_only(const struct option *opt,
 190                          const char *arg, int unset)
 191{
 192        fast_forward = FF_ONLY;
 193        return 0;
 194}
 195
 196static struct option builtin_merge_options[] = {
 197        { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
 198                N_("do not show a diffstat at the end of the merge"),
 199                PARSE_OPT_NOARG, option_parse_n },
 200        OPT_BOOL(0, "stat", &show_diffstat,
 201                N_("show a diffstat at the end of the merge")),
 202        OPT_BOOL(0, "summary", &show_diffstat, N_("(synonym to --stat)")),
 203        { OPTION_INTEGER, 0, "log", &shortlog_len, N_("n"),
 204          N_("add (at most <n>) entries from shortlog to merge commit message"),
 205          PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
 206        OPT_BOOL(0, "squash", &squash,
 207                N_("create a single commit instead of doing a merge")),
 208        OPT_BOOL(0, "commit", &option_commit,
 209                N_("perform a commit if the merge succeeds (default)")),
 210        OPT_BOOL('e', "edit", &option_edit,
 211                N_("edit message before committing")),
 212        OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
 213        { OPTION_CALLBACK, 0, "ff-only", NULL, NULL,
 214                N_("abort if fast-forward is not possible"),
 215                PARSE_OPT_NOARG | PARSE_OPT_NONEG, option_parse_ff_only },
 216        OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
 217        OPT_BOOL(0, "verify-signatures", &verify_signatures,
 218                N_("Verify that the named commit has a valid GPG signature")),
 219        OPT_CALLBACK('s', "strategy", &use_strategies, N_("strategy"),
 220                N_("merge strategy to use"), option_parse_strategy),
 221        OPT_CALLBACK('X', "strategy-option", &xopts, N_("option=value"),
 222                N_("option for selected merge strategy"), option_parse_x),
 223        OPT_CALLBACK('m', "message", &merge_msg, N_("message"),
 224                N_("merge commit message (for a non-fast-forward merge)"),
 225                option_parse_message),
 226        OPT__VERBOSITY(&verbosity),
 227        OPT_BOOL(0, "abort", &abort_current_merge,
 228                N_("abort the current in-progress merge")),
 229        OPT_SET_INT(0, "progress", &show_progress, N_("force progress reporting"), 1),
 230        { OPTION_STRING, 'S', "gpg-sign", &sign_commit, N_("key id"),
 231          N_("GPG sign commit"), PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
 232        OPT_BOOL(0, "overwrite-ignore", &overwrite_ignore, N_("update ignored files (default)")),
 233        OPT_END()
 234};
 235
 236/* Cleans up metadata that is uninteresting after a succeeded merge. */
 237static void drop_save(void)
 238{
 239        unlink(git_path("MERGE_HEAD"));
 240        unlink(git_path("MERGE_MSG"));
 241        unlink(git_path("MERGE_MODE"));
 242}
 243
 244static int save_state(unsigned char *stash)
 245{
 246        int len;
 247        struct child_process cp;
 248        struct strbuf buffer = STRBUF_INIT;
 249        const char *argv[] = {"stash", "create", NULL};
 250
 251        memset(&cp, 0, sizeof(cp));
 252        cp.argv = argv;
 253        cp.out = -1;
 254        cp.git_cmd = 1;
 255
 256        if (start_command(&cp))
 257                die(_("could not run stash."));
 258        len = strbuf_read(&buffer, cp.out, 1024);
 259        close(cp.out);
 260
 261        if (finish_command(&cp) || len < 0)
 262                die(_("stash failed"));
 263        else if (!len)          /* no changes */
 264                return -1;
 265        strbuf_setlen(&buffer, buffer.len-1);
 266        if (get_sha1(buffer.buf, stash))
 267                die(_("not a valid object: %s"), buffer.buf);
 268        return 0;
 269}
 270
 271static void read_empty(unsigned const char *sha1, int verbose)
 272{
 273        int i = 0;
 274        const char *args[7];
 275
 276        args[i++] = "read-tree";
 277        if (verbose)
 278                args[i++] = "-v";
 279        args[i++] = "-m";
 280        args[i++] = "-u";
 281        args[i++] = EMPTY_TREE_SHA1_HEX;
 282        args[i++] = sha1_to_hex(sha1);
 283        args[i] = NULL;
 284
 285        if (run_command_v_opt(args, RUN_GIT_CMD))
 286                die(_("read-tree failed"));
 287}
 288
 289static void reset_hard(unsigned const char *sha1, int verbose)
 290{
 291        int i = 0;
 292        const char *args[6];
 293
 294        args[i++] = "read-tree";
 295        if (verbose)
 296                args[i++] = "-v";
 297        args[i++] = "--reset";
 298        args[i++] = "-u";
 299        args[i++] = sha1_to_hex(sha1);
 300        args[i] = NULL;
 301
 302        if (run_command_v_opt(args, RUN_GIT_CMD))
 303                die(_("read-tree failed"));
 304}
 305
 306static void restore_state(const unsigned char *head,
 307                          const unsigned char *stash)
 308{
 309        struct strbuf sb = STRBUF_INIT;
 310        const char *args[] = { "stash", "apply", NULL, NULL };
 311
 312        if (is_null_sha1(stash))
 313                return;
 314
 315        reset_hard(head, 1);
 316
 317        args[2] = sha1_to_hex(stash);
 318
 319        /*
 320         * It is OK to ignore error here, for example when there was
 321         * nothing to restore.
 322         */
 323        run_command_v_opt(args, RUN_GIT_CMD);
 324
 325        strbuf_release(&sb);
 326        refresh_cache(REFRESH_QUIET);
 327}
 328
 329/* This is called when no merge was necessary. */
 330static void finish_up_to_date(const char *msg)
 331{
 332        if (verbosity >= 0)
 333                printf("%s%s\n", squash ? _(" (nothing to squash)") : "", msg);
 334        drop_save();
 335}
 336
 337static void squash_message(struct commit *commit, struct commit_list *remoteheads)
 338{
 339        struct rev_info rev;
 340        struct strbuf out = STRBUF_INIT;
 341        struct commit_list *j;
 342        const char *filename;
 343        int fd;
 344        struct pretty_print_context ctx = {0};
 345
 346        printf(_("Squash commit -- not updating HEAD\n"));
 347        filename = git_path("SQUASH_MSG");
 348        fd = open(filename, O_WRONLY | O_CREAT, 0666);
 349        if (fd < 0)
 350                die_errno(_("Could not write to '%s'"), filename);
 351
 352        init_revisions(&rev, NULL);
 353        rev.ignore_merges = 1;
 354        rev.commit_format = CMIT_FMT_MEDIUM;
 355
 356        commit->object.flags |= UNINTERESTING;
 357        add_pending_object(&rev, &commit->object, NULL);
 358
 359        for (j = remoteheads; j; j = j->next)
 360                add_pending_object(&rev, &j->item->object, NULL);
 361
 362        setup_revisions(0, NULL, &rev, NULL);
 363        if (prepare_revision_walk(&rev))
 364                die(_("revision walk setup failed"));
 365
 366        ctx.abbrev = rev.abbrev;
 367        ctx.date_mode = rev.date_mode;
 368        ctx.fmt = rev.commit_format;
 369
 370        strbuf_addstr(&out, "Squashed commit of the following:\n");
 371        while ((commit = get_revision(&rev)) != NULL) {
 372                strbuf_addch(&out, '\n');
 373                strbuf_addf(&out, "commit %s\n",
 374                        sha1_to_hex(commit->object.sha1));
 375                pretty_print_commit(&ctx, commit, &out);
 376        }
 377        if (write(fd, out.buf, out.len) < 0)
 378                die_errno(_("Writing SQUASH_MSG"));
 379        if (close(fd))
 380                die_errno(_("Finishing SQUASH_MSG"));
 381        strbuf_release(&out);
 382}
 383
 384static void finish(struct commit *head_commit,
 385                   struct commit_list *remoteheads,
 386                   const unsigned char *new_head, const char *msg)
 387{
 388        struct strbuf reflog_message = STRBUF_INIT;
 389        const unsigned char *head = head_commit->object.sha1;
 390
 391        if (!msg)
 392                strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
 393        else {
 394                if (verbosity >= 0)
 395                        printf("%s\n", msg);
 396                strbuf_addf(&reflog_message, "%s: %s",
 397                        getenv("GIT_REFLOG_ACTION"), msg);
 398        }
 399        if (squash) {
 400                squash_message(head_commit, remoteheads);
 401        } else {
 402                if (verbosity >= 0 && !merge_msg.len)
 403                        printf(_("No merge message -- not updating HEAD\n"));
 404                else {
 405                        const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 406                        update_ref(reflog_message.buf, "HEAD",
 407                                new_head, head, 0,
 408                                DIE_ON_ERR);
 409                        /*
 410                         * We ignore errors in 'gc --auto', since the
 411                         * user should see them.
 412                         */
 413                        run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 414                }
 415        }
 416        if (new_head && show_diffstat) {
 417                struct diff_options opts;
 418                diff_setup(&opts);
 419                opts.stat_width = -1; /* use full terminal width */
 420                opts.stat_graph_width = -1; /* respect statGraphWidth config */
 421                opts.output_format |=
 422                        DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 423                opts.detect_rename = DIFF_DETECT_RENAME;
 424                diff_setup_done(&opts);
 425                diff_tree_sha1(head, new_head, "", &opts);
 426                diffcore_std(&opts);
 427                diff_flush(&opts);
 428        }
 429
 430        /* Run a post-merge hook */
 431        run_hook(NULL, "post-merge", squash ? "1" : "0", NULL);
 432
 433        strbuf_release(&reflog_message);
 434}
 435
 436/* Get the name for the merge commit's message. */
 437static void merge_name(const char *remote, struct strbuf *msg)
 438{
 439        struct commit *remote_head;
 440        unsigned char branch_head[20];
 441        struct strbuf buf = STRBUF_INIT;
 442        struct strbuf bname = STRBUF_INIT;
 443        const char *ptr;
 444        char *found_ref;
 445        int len, early;
 446
 447        strbuf_branchname(&bname, remote);
 448        remote = bname.buf;
 449
 450        memset(branch_head, 0, sizeof(branch_head));
 451        remote_head = get_merge_parent(remote);
 452        if (!remote_head)
 453                die(_("'%s' does not point to a commit"), remote);
 454
 455        if (dwim_ref(remote, strlen(remote), branch_head, &found_ref) > 0) {
 456                if (!prefixcmp(found_ref, "refs/heads/")) {
 457                        strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 458                                    sha1_to_hex(branch_head), remote);
 459                        goto cleanup;
 460                }
 461                if (!prefixcmp(found_ref, "refs/tags/")) {
 462                        strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
 463                                    sha1_to_hex(branch_head), remote);
 464                        goto cleanup;
 465                }
 466                if (!prefixcmp(found_ref, "refs/remotes/")) {
 467                        strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
 468                                    sha1_to_hex(branch_head), remote);
 469                        goto cleanup;
 470                }
 471        }
 472
 473        /* See if remote matches <name>^^^.. or <name>~<number> */
 474        for (len = 0, ptr = remote + strlen(remote);
 475             remote < ptr && ptr[-1] == '^';
 476             ptr--)
 477                len++;
 478        if (len)
 479                early = 1;
 480        else {
 481                early = 0;
 482                ptr = strrchr(remote, '~');
 483                if (ptr) {
 484                        int seen_nonzero = 0;
 485
 486                        len++; /* count ~ */
 487                        while (*++ptr && isdigit(*ptr)) {
 488                                seen_nonzero |= (*ptr != '0');
 489                                len++;
 490                        }
 491                        if (*ptr)
 492                                len = 0; /* not ...~<number> */
 493                        else if (seen_nonzero)
 494                                early = 1;
 495                        else if (len == 1)
 496                                early = 1; /* "name~" is "name~1"! */
 497                }
 498        }
 499        if (len) {
 500                struct strbuf truname = STRBUF_INIT;
 501                strbuf_addstr(&truname, "refs/heads/");
 502                strbuf_addstr(&truname, remote);
 503                strbuf_setlen(&truname, truname.len - len);
 504                if (ref_exists(truname.buf)) {
 505                        strbuf_addf(msg,
 506                                    "%s\t\tbranch '%s'%s of .\n",
 507                                    sha1_to_hex(remote_head->object.sha1),
 508                                    truname.buf + 11,
 509                                    (early ? " (early part)" : ""));
 510                        strbuf_release(&truname);
 511                        goto cleanup;
 512                }
 513        }
 514
 515        if (!strcmp(remote, "FETCH_HEAD") &&
 516                        !access(git_path("FETCH_HEAD"), R_OK)) {
 517                const char *filename;
 518                FILE *fp;
 519                struct strbuf line = STRBUF_INIT;
 520                char *ptr;
 521
 522                filename = git_path("FETCH_HEAD");
 523                fp = fopen(filename, "r");
 524                if (!fp)
 525                        die_errno(_("could not open '%s' for reading"),
 526                                  filename);
 527                strbuf_getline(&line, fp, '\n');
 528                fclose(fp);
 529                ptr = strstr(line.buf, "\tnot-for-merge\t");
 530                if (ptr)
 531                        strbuf_remove(&line, ptr-line.buf+1, 13);
 532                strbuf_addbuf(msg, &line);
 533                strbuf_release(&line);
 534                goto cleanup;
 535        }
 536
 537        if (remote_head->util) {
 538                struct merge_remote_desc *desc;
 539                desc = merge_remote_util(remote_head);
 540                if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
 541                        strbuf_addf(msg, "%s\t\t%s '%s'\n",
 542                                    sha1_to_hex(desc->obj->sha1),
 543                                    typename(desc->obj->type),
 544                                    remote);
 545                        goto cleanup;
 546                }
 547        }
 548
 549        strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 550                sha1_to_hex(remote_head->object.sha1), remote);
 551cleanup:
 552        strbuf_release(&buf);
 553        strbuf_release(&bname);
 554}
 555
 556static void parse_branch_merge_options(char *bmo)
 557{
 558        const char **argv;
 559        int argc;
 560
 561        if (!bmo)
 562                return;
 563        argc = split_cmdline(bmo, &argv);
 564        if (argc < 0)
 565                die(_("Bad branch.%s.mergeoptions string: %s"), branch,
 566                    split_cmdline_strerror(argc));
 567        argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
 568        memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
 569        argc++;
 570        argv[0] = "branch.*.mergeoptions";
 571        parse_options(argc, argv, NULL, builtin_merge_options,
 572                      builtin_merge_usage, 0);
 573        free(argv);
 574}
 575
 576static int git_merge_config(const char *k, const char *v, void *cb)
 577{
 578        int status;
 579
 580        if (branch && !prefixcmp(k, "branch.") &&
 581                !prefixcmp(k + 7, branch) &&
 582                !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
 583                free(branch_mergeoptions);
 584                branch_mergeoptions = xstrdup(v);
 585                return 0;
 586        }
 587
 588        if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 589                show_diffstat = git_config_bool(k, v);
 590        else if (!strcmp(k, "pull.twohead"))
 591                return git_config_string(&pull_twohead, k, v);
 592        else if (!strcmp(k, "pull.octopus"))
 593                return git_config_string(&pull_octopus, k, v);
 594        else if (!strcmp(k, "merge.renormalize"))
 595                option_renormalize = git_config_bool(k, v);
 596        else if (!strcmp(k, "merge.ff")) {
 597                int boolval = git_config_maybe_bool(k, v);
 598                if (0 <= boolval) {
 599                        fast_forward = boolval ? FF_ALLOW : FF_NO;
 600                } else if (v && !strcmp(v, "only")) {
 601                        fast_forward = FF_ONLY;
 602                } /* do not barf on values from future versions of git */
 603                return 0;
 604        } else if (!strcmp(k, "merge.defaulttoupstream")) {
 605                default_to_upstream = git_config_bool(k, v);
 606                return 0;
 607        }
 608
 609        status = fmt_merge_msg_config(k, v, cb);
 610        if (status)
 611                return status;
 612        status = git_gpg_config(k, v, NULL);
 613        if (status)
 614                return status;
 615        return git_diff_ui_config(k, v, cb);
 616}
 617
 618static int read_tree_trivial(unsigned char *common, unsigned char *head,
 619                             unsigned char *one)
 620{
 621        int i, nr_trees = 0;
 622        struct tree *trees[MAX_UNPACK_TREES];
 623        struct tree_desc t[MAX_UNPACK_TREES];
 624        struct unpack_trees_options opts;
 625
 626        memset(&opts, 0, sizeof(opts));
 627        opts.head_idx = 2;
 628        opts.src_index = &the_index;
 629        opts.dst_index = &the_index;
 630        opts.update = 1;
 631        opts.verbose_update = 1;
 632        opts.trivial_merges_only = 1;
 633        opts.merge = 1;
 634        trees[nr_trees] = parse_tree_indirect(common);
 635        if (!trees[nr_trees++])
 636                return -1;
 637        trees[nr_trees] = parse_tree_indirect(head);
 638        if (!trees[nr_trees++])
 639                return -1;
 640        trees[nr_trees] = parse_tree_indirect(one);
 641        if (!trees[nr_trees++])
 642                return -1;
 643        opts.fn = threeway_merge;
 644        cache_tree_free(&active_cache_tree);
 645        for (i = 0; i < nr_trees; i++) {
 646                parse_tree(trees[i]);
 647                init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 648        }
 649        if (unpack_trees(nr_trees, t, &opts))
 650                return -1;
 651        return 0;
 652}
 653
 654static void write_tree_trivial(unsigned char *sha1)
 655{
 656        if (write_cache_as_tree(sha1, 0, NULL))
 657                die(_("git write-tree failed to write a tree"));
 658}
 659
 660static int try_merge_strategy(const char *strategy, struct commit_list *common,
 661                              struct commit_list *remoteheads,
 662                              struct commit *head, const char *head_arg)
 663{
 664        int index_fd;
 665        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 666
 667        index_fd = hold_locked_index(lock, 1);
 668        refresh_cache(REFRESH_QUIET);
 669        if (active_cache_changed &&
 670                        (write_cache(index_fd, active_cache, active_nr) ||
 671                         commit_locked_index(lock)))
 672                return error(_("Unable to write index."));
 673        rollback_lock_file(lock);
 674
 675        if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
 676                int clean, x;
 677                struct commit *result;
 678                struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 679                int index_fd;
 680                struct commit_list *reversed = NULL;
 681                struct merge_options o;
 682                struct commit_list *j;
 683
 684                if (remoteheads->next) {
 685                        error(_("Not handling anything other than two heads merge."));
 686                        return 2;
 687                }
 688
 689                init_merge_options(&o);
 690                if (!strcmp(strategy, "subtree"))
 691                        o.subtree_shift = "";
 692
 693                o.renormalize = option_renormalize;
 694                o.show_rename_progress =
 695                        show_progress == -1 ? isatty(2) : show_progress;
 696
 697                for (x = 0; x < xopts_nr; x++)
 698                        if (parse_merge_opt(&o, xopts[x]))
 699                                die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
 700
 701                o.branch1 = head_arg;
 702                o.branch2 = merge_remote_util(remoteheads->item)->name;
 703
 704                for (j = common; j; j = j->next)
 705                        commit_list_insert(j->item, &reversed);
 706
 707                index_fd = hold_locked_index(lock, 1);
 708                clean = merge_recursive(&o, head,
 709                                remoteheads->item, reversed, &result);
 710                if (active_cache_changed &&
 711                                (write_cache(index_fd, active_cache, active_nr) ||
 712                                 commit_locked_index(lock)))
 713                        die (_("unable to write %s"), get_index_file());
 714                rollback_lock_file(lock);
 715                return clean ? 0 : 1;
 716        } else {
 717                return try_merge_command(strategy, xopts_nr, xopts,
 718                                                common, head_arg, remoteheads);
 719        }
 720}
 721
 722static void count_diff_files(struct diff_queue_struct *q,
 723                             struct diff_options *opt, void *data)
 724{
 725        int *count = data;
 726
 727        (*count) += q->nr;
 728}
 729
 730static int count_unmerged_entries(void)
 731{
 732        int i, ret = 0;
 733
 734        for (i = 0; i < active_nr; i++)
 735                if (ce_stage(active_cache[i]))
 736                        ret++;
 737
 738        return ret;
 739}
 740
 741static void split_merge_strategies(const char *string, struct strategy **list,
 742                                   int *nr, int *alloc)
 743{
 744        char *p, *q, *buf;
 745
 746        if (!string)
 747                return;
 748
 749        buf = xstrdup(string);
 750        q = buf;
 751        for (;;) {
 752                p = strchr(q, ' ');
 753                if (!p) {
 754                        ALLOC_GROW(*list, *nr + 1, *alloc);
 755                        (*list)[(*nr)++].name = xstrdup(q);
 756                        free(buf);
 757                        return;
 758                } else {
 759                        *p = '\0';
 760                        ALLOC_GROW(*list, *nr + 1, *alloc);
 761                        (*list)[(*nr)++].name = xstrdup(q);
 762                        q = ++p;
 763                }
 764        }
 765}
 766
 767static void add_strategies(const char *string, unsigned attr)
 768{
 769        struct strategy *list = NULL;
 770        int list_alloc = 0, list_nr = 0, i;
 771
 772        memset(&list, 0, sizeof(list));
 773        split_merge_strategies(string, &list, &list_nr, &list_alloc);
 774        if (list) {
 775                for (i = 0; i < list_nr; i++)
 776                        append_strategy(get_strategy(list[i].name));
 777                return;
 778        }
 779        for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 780                if (all_strategy[i].attr & attr)
 781                        append_strategy(&all_strategy[i]);
 782
 783}
 784
 785static void write_merge_msg(struct strbuf *msg)
 786{
 787        const char *filename = git_path("MERGE_MSG");
 788        int fd = open(filename, O_WRONLY | O_CREAT, 0666);
 789        if (fd < 0)
 790                die_errno(_("Could not open '%s' for writing"),
 791                          filename);
 792        if (write_in_full(fd, msg->buf, msg->len) != msg->len)
 793                die_errno(_("Could not write to '%s'"), filename);
 794        close(fd);
 795}
 796
 797static void read_merge_msg(struct strbuf *msg)
 798{
 799        const char *filename = git_path("MERGE_MSG");
 800        strbuf_reset(msg);
 801        if (strbuf_read_file(msg, filename, 0) < 0)
 802                die_errno(_("Could not read from '%s'"), filename);
 803}
 804
 805static void write_merge_state(struct commit_list *);
 806static void abort_commit(struct commit_list *remoteheads, const char *err_msg)
 807{
 808        if (err_msg)
 809                error("%s", err_msg);
 810        fprintf(stderr,
 811                _("Not committing merge; use 'git commit' to complete the merge.\n"));
 812        write_merge_state(remoteheads);
 813        exit(1);
 814}
 815
 816static const char merge_editor_comment[] =
 817N_("Please enter a commit message to explain why this merge is necessary,\n"
 818   "especially if it merges an updated upstream into a topic branch.\n"
 819   "\n"
 820   "Lines starting with '%c' will be ignored, and an empty message aborts\n"
 821   "the commit.\n");
 822
 823static void prepare_to_commit(struct commit_list *remoteheads)
 824{
 825        struct strbuf msg = STRBUF_INIT;
 826        strbuf_addbuf(&msg, &merge_msg);
 827        strbuf_addch(&msg, '\n');
 828        if (0 < option_edit)
 829                strbuf_commented_addf(&msg, _(merge_editor_comment), comment_line_char);
 830        write_merge_msg(&msg);
 831        if (run_hook(get_index_file(), "prepare-commit-msg",
 832                     git_path("MERGE_MSG"), "merge", NULL, NULL))
 833                abort_commit(remoteheads, NULL);
 834        if (0 < option_edit) {
 835                if (launch_editor(git_path("MERGE_MSG"), NULL, NULL))
 836                        abort_commit(remoteheads, NULL);
 837        }
 838        read_merge_msg(&msg);
 839        stripspace(&msg, 0 < option_edit);
 840        if (!msg.len)
 841                abort_commit(remoteheads, _("Empty commit message."));
 842        strbuf_release(&merge_msg);
 843        strbuf_addbuf(&merge_msg, &msg);
 844        strbuf_release(&msg);
 845}
 846
 847static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
 848{
 849        unsigned char result_tree[20], result_commit[20];
 850        struct commit_list *parent = xmalloc(sizeof(*parent));
 851
 852        write_tree_trivial(result_tree);
 853        printf(_("Wonderful.\n"));
 854        parent->item = head;
 855        parent->next = xmalloc(sizeof(*parent->next));
 856        parent->next->item = remoteheads->item;
 857        parent->next->next = NULL;
 858        prepare_to_commit(remoteheads);
 859        if (commit_tree(&merge_msg, result_tree, parent, result_commit, NULL,
 860                        sign_commit))
 861                die(_("failed to write commit object"));
 862        finish(head, remoteheads, result_commit, "In-index merge");
 863        drop_save();
 864        return 0;
 865}
 866
 867static int finish_automerge(struct commit *head,
 868                            int head_subsumed,
 869                            struct commit_list *common,
 870                            struct commit_list *remoteheads,
 871                            unsigned char *result_tree,
 872                            const char *wt_strategy)
 873{
 874        struct commit_list *parents = NULL;
 875        struct strbuf buf = STRBUF_INIT;
 876        unsigned char result_commit[20];
 877
 878        free_commit_list(common);
 879        parents = remoteheads;
 880        if (!head_subsumed || fast_forward == FF_NO)
 881                commit_list_insert(head, &parents);
 882        strbuf_addch(&merge_msg, '\n');
 883        prepare_to_commit(remoteheads);
 884        if (commit_tree(&merge_msg, result_tree, parents, result_commit,
 885                        NULL, sign_commit))
 886                die(_("failed to write commit object"));
 887        strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
 888        finish(head, remoteheads, result_commit, buf.buf);
 889        strbuf_release(&buf);
 890        drop_save();
 891        return 0;
 892}
 893
 894static int suggest_conflicts(int renormalizing)
 895{
 896        const char *filename;
 897        FILE *fp;
 898        int pos;
 899
 900        filename = git_path("MERGE_MSG");
 901        fp = fopen(filename, "a");
 902        if (!fp)
 903                die_errno(_("Could not open '%s' for writing"), filename);
 904        fprintf(fp, "\nConflicts:\n");
 905        for (pos = 0; pos < active_nr; pos++) {
 906                const struct cache_entry *ce = active_cache[pos];
 907
 908                if (ce_stage(ce)) {
 909                        fprintf(fp, "\t%s\n", ce->name);
 910                        while (pos + 1 < active_nr &&
 911                                        !strcmp(ce->name,
 912                                                active_cache[pos + 1]->name))
 913                                pos++;
 914                }
 915        }
 916        fclose(fp);
 917        rerere(allow_rerere_auto);
 918        printf(_("Automatic merge failed; "
 919                        "fix conflicts and then commit the result.\n"));
 920        return 1;
 921}
 922
 923static struct commit *is_old_style_invocation(int argc, const char **argv,
 924                                              const unsigned char *head)
 925{
 926        struct commit *second_token = NULL;
 927        if (argc > 2) {
 928                unsigned char second_sha1[20];
 929
 930                if (get_sha1(argv[1], second_sha1))
 931                        return NULL;
 932                second_token = lookup_commit_reference_gently(second_sha1, 0);
 933                if (!second_token)
 934                        die(_("'%s' is not a commit"), argv[1]);
 935                if (hashcmp(second_token->object.sha1, head))
 936                        return NULL;
 937        }
 938        return second_token;
 939}
 940
 941static int evaluate_result(void)
 942{
 943        int cnt = 0;
 944        struct rev_info rev;
 945
 946        /* Check how many files differ. */
 947        init_revisions(&rev, "");
 948        setup_revisions(0, NULL, &rev, NULL);
 949        rev.diffopt.output_format |=
 950                DIFF_FORMAT_CALLBACK;
 951        rev.diffopt.format_callback = count_diff_files;
 952        rev.diffopt.format_callback_data = &cnt;
 953        run_diff_files(&rev, 0);
 954
 955        /*
 956         * Check how many unmerged entries are
 957         * there.
 958         */
 959        cnt += count_unmerged_entries();
 960
 961        return cnt;
 962}
 963
 964/*
 965 * Pretend as if the user told us to merge with the remote-tracking
 966 * branch we have for the upstream of the current branch
 967 */
 968static int setup_with_upstream(const char ***argv)
 969{
 970        struct branch *branch = branch_get(NULL);
 971        int i;
 972        const char **args;
 973
 974        if (!branch)
 975                die(_("No current branch."));
 976        if (!branch->remote)
 977                die(_("No remote for the current branch."));
 978        if (!branch->merge_nr)
 979                die(_("No default upstream defined for the current branch."));
 980
 981        args = xcalloc(branch->merge_nr + 1, sizeof(char *));
 982        for (i = 0; i < branch->merge_nr; i++) {
 983                if (!branch->merge[i]->dst)
 984                        die(_("No remote-tracking branch for %s from %s"),
 985                            branch->merge[i]->src, branch->remote_name);
 986                args[i] = branch->merge[i]->dst;
 987        }
 988        args[i] = NULL;
 989        *argv = args;
 990        return i;
 991}
 992
 993static void write_merge_state(struct commit_list *remoteheads)
 994{
 995        const char *filename;
 996        int fd;
 997        struct commit_list *j;
 998        struct strbuf buf = STRBUF_INIT;
 999
1000        for (j = remoteheads; j; j = j->next) {
1001                unsigned const char *sha1;
1002                struct commit *c = j->item;
1003                if (c->util && merge_remote_util(c)->obj) {
1004                        sha1 = merge_remote_util(c)->obj->sha1;
1005                } else {
1006                        sha1 = c->object.sha1;
1007                }
1008                strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
1009        }
1010        filename = git_path("MERGE_HEAD");
1011        fd = open(filename, O_WRONLY | O_CREAT, 0666);
1012        if (fd < 0)
1013                die_errno(_("Could not open '%s' for writing"), filename);
1014        if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1015                die_errno(_("Could not write to '%s'"), filename);
1016        close(fd);
1017        strbuf_addch(&merge_msg, '\n');
1018        write_merge_msg(&merge_msg);
1019
1020        filename = git_path("MERGE_MODE");
1021        fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
1022        if (fd < 0)
1023                die_errno(_("Could not open '%s' for writing"), filename);
1024        strbuf_reset(&buf);
1025        if (fast_forward == FF_NO)
1026                strbuf_addf(&buf, "no-ff");
1027        if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1028                die_errno(_("Could not write to '%s'"), filename);
1029        close(fd);
1030}
1031
1032static 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_config_maybe_bool(name, 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
1058static struct commit_list *collect_parents(struct commit *head_commit,
1059                                           int *head_subsumed,
1060                                           int argc, const char **argv)
1061{
1062        int i;
1063        struct commit_list *remoteheads = NULL, *parents, *next;
1064        struct commit_list **remotes = &remoteheads;
1065
1066        if (head_commit)
1067                remotes = &commit_list_insert(head_commit, remotes)->next;
1068        for (i = 0; i < argc; i++) {
1069                struct commit *commit = get_merge_parent(argv[i]);
1070                if (!commit)
1071                        help_unknown_ref(argv[i], "merge",
1072                                         "not something we can merge");
1073                remotes = &commit_list_insert(commit, remotes)->next;
1074        }
1075        *remotes = NULL;
1076
1077        parents = reduce_heads(remoteheads);
1078
1079        *head_subsumed = 1; /* we will flip this to 0 when we find it */
1080        for (remoteheads = NULL, remotes = &remoteheads;
1081             parents;
1082             parents = next) {
1083                struct commit *commit = parents->item;
1084                next = parents->next;
1085                if (commit == head_commit)
1086                        *head_subsumed = 0;
1087                else
1088                        remotes = &commit_list_insert(commit, remotes)->next;
1089        }
1090        return remoteheads;
1091}
1092
1093int cmd_merge(int argc, const char **argv, const char *prefix)
1094{
1095        unsigned char result_tree[20];
1096        unsigned char stash[20];
1097        unsigned char head_sha1[20];
1098        struct commit *head_commit;
1099        struct strbuf buf = STRBUF_INIT;
1100        const char *head_arg;
1101        int flag, i, ret = 0, head_subsumed;
1102        int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
1103        struct commit_list *common = NULL;
1104        const char *best_strategy = NULL, *wt_strategy = NULL;
1105        struct commit_list *remoteheads, *p;
1106        void *branch_to_free;
1107
1108        if (argc == 2 && !strcmp(argv[1], "-h"))
1109                usage_with_options(builtin_merge_usage, builtin_merge_options);
1110
1111        /*
1112         * Check if we are _not_ on a detached HEAD, i.e. if there is a
1113         * current branch.
1114         */
1115        branch = branch_to_free = resolve_refdup("HEAD", head_sha1, 0, &flag);
1116        if (branch && !prefixcmp(branch, "refs/heads/"))
1117                branch += 11;
1118        if (!branch || is_null_sha1(head_sha1))
1119                head_commit = NULL;
1120        else
1121                head_commit = lookup_commit_or_die(head_sha1, "HEAD");
1122
1123        git_config(git_merge_config, NULL);
1124
1125        if (branch_mergeoptions)
1126                parse_branch_merge_options(branch_mergeoptions);
1127        argc = parse_options(argc, argv, prefix, builtin_merge_options,
1128                        builtin_merge_usage, 0);
1129        if (shortlog_len < 0)
1130                shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;
1131
1132        if (verbosity < 0 && show_progress == -1)
1133                show_progress = 0;
1134
1135        if (abort_current_merge) {
1136                int nargc = 2;
1137                const char *nargv[] = {"reset", "--merge", NULL};
1138
1139                if (!file_exists(git_path("MERGE_HEAD")))
1140                        die(_("There is no merge to abort (MERGE_HEAD missing)."));
1141
1142                /* Invoke 'git reset --merge' */
1143                ret = cmd_reset(nargc, nargv, prefix);
1144                goto done;
1145        }
1146
1147        if (read_cache_unmerged())
1148                die_resolve_conflict("merge");
1149
1150        if (file_exists(git_path("MERGE_HEAD"))) {
1151                /*
1152                 * There is no unmerged entry, don't advise 'git
1153                 * add/rm <file>', just 'git commit'.
1154                 */
1155                if (advice_resolve_conflict)
1156                        die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1157                                  "Please, commit your changes before you can merge."));
1158                else
1159                        die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1160        }
1161        if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
1162                if (advice_resolve_conflict)
1163                        die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1164                            "Please, commit your changes before you can merge."));
1165                else
1166                        die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
1167        }
1168        resolve_undo_clear();
1169
1170        if (verbosity < 0)
1171                show_diffstat = 0;
1172
1173        if (squash) {
1174                if (fast_forward == FF_NO)
1175                        die(_("You cannot combine --squash with --no-ff."));
1176                option_commit = 0;
1177        }
1178
1179        if (!abort_current_merge) {
1180                if (!argc) {
1181                        if (default_to_upstream)
1182                                argc = setup_with_upstream(&argv);
1183                        else
1184                                die(_("No commit specified and merge.defaultToUpstream not set."));
1185                } else if (argc == 1 && !strcmp(argv[0], "-"))
1186                        argv[0] = "@{-1}";
1187        }
1188        if (!argc)
1189                usage_with_options(builtin_merge_usage,
1190                        builtin_merge_options);
1191
1192        /*
1193         * This could be traditional "merge <msg> HEAD <commit>..."  and
1194         * the way we can tell it is to see if the second token is HEAD,
1195         * but some people might have misused the interface and used a
1196         * commit-ish that is the same as HEAD there instead.
1197         * Traditional format never would have "-m" so it is an
1198         * additional safety measure to check for it.
1199         */
1200
1201        if (!have_message && head_commit &&
1202            is_old_style_invocation(argc, argv, head_commit->object.sha1)) {
1203                strbuf_addstr(&merge_msg, argv[0]);
1204                head_arg = argv[1];
1205                argv += 2;
1206                argc -= 2;
1207                remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
1208        } else if (!head_commit) {
1209                struct commit *remote_head;
1210                /*
1211                 * If the merged head is a valid one there is no reason
1212                 * to forbid "git merge" into a branch yet to be born.
1213                 * We do the same for "git pull".
1214                 */
1215                if (argc != 1)
1216                        die(_("Can merge only exactly one commit into "
1217                                "empty head"));
1218                if (squash)
1219                        die(_("Squash commit into empty head not supported yet"));
1220                if (fast_forward == FF_NO)
1221                        die(_("Non-fast-forward commit does not make sense into "
1222                            "an empty head"));
1223                remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
1224                remote_head = remoteheads->item;
1225                if (!remote_head)
1226                        die(_("%s - not something we can merge"), argv[0]);
1227                read_empty(remote_head->object.sha1, 0);
1228                update_ref("initial pull", "HEAD", remote_head->object.sha1,
1229                           NULL, 0, DIE_ON_ERR);
1230                goto done;
1231        } else {
1232                struct strbuf merge_names = STRBUF_INIT;
1233
1234                /* We are invoked directly as the first-class UI. */
1235                head_arg = "HEAD";
1236
1237                /*
1238                 * All the rest are the commits being merged; prepare
1239                 * the standard merge summary message to be appended
1240                 * to the given message.
1241                 */
1242                remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
1243                for (p = remoteheads; p; p = p->next)
1244                        merge_name(merge_remote_util(p->item)->name, &merge_names);
1245
1246                if (!have_message || shortlog_len) {
1247                        struct fmt_merge_msg_opts opts;
1248                        memset(&opts, 0, sizeof(opts));
1249                        opts.add_title = !have_message;
1250                        opts.shortlog_len = shortlog_len;
1251                        opts.credit_people = (0 < option_edit);
1252
1253                        fmt_merge_msg(&merge_names, &merge_msg, &opts);
1254                        if (merge_msg.len)
1255                                strbuf_setlen(&merge_msg, merge_msg.len - 1);
1256                }
1257        }
1258
1259        if (!head_commit || !argc)
1260                usage_with_options(builtin_merge_usage,
1261                        builtin_merge_options);
1262
1263        if (verify_signatures) {
1264                for (p = remoteheads; p; p = p->next) {
1265                        struct commit *commit = p->item;
1266                        char hex[41];
1267                        struct signature_check signature_check;
1268                        memset(&signature_check, 0, sizeof(signature_check));
1269
1270                        check_commit_signature(commit, &signature_check);
1271
1272                        strcpy(hex, find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
1273                        switch (signature_check.result) {
1274                        case 'G':
1275                                break;
1276                        case 'U':
1277                                die(_("Commit %s has an untrusted GPG signature, "
1278                                      "allegedly by %s."), hex, signature_check.signer);
1279                        case 'B':
1280                                die(_("Commit %s has a bad GPG signature "
1281                                      "allegedly by %s."), hex, signature_check.signer);
1282                        default: /* 'N' */
1283                                die(_("Commit %s does not have a GPG signature."), hex);
1284                        }
1285                        if (verbosity >= 0 && signature_check.result == 'G')
1286                                printf(_("Commit %s has a good GPG signature by %s\n"),
1287                                       hex, signature_check.signer);
1288
1289                        free(signature_check.gpg_output);
1290                        free(signature_check.gpg_status);
1291                        free(signature_check.signer);
1292                        free(signature_check.key);
1293                }
1294        }
1295
1296        strbuf_addstr(&buf, "merge");
1297        for (p = remoteheads; p; p = p->next)
1298                strbuf_addf(&buf, " %s", merge_remote_util(p->item)->name);
1299        setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1300        strbuf_reset(&buf);
1301
1302        for (p = remoteheads; p; p = p->next) {
1303                struct commit *commit = p->item;
1304                strbuf_addf(&buf, "GITHEAD_%s",
1305                            sha1_to_hex(commit->object.sha1));
1306                setenv(buf.buf, merge_remote_util(commit)->name, 1);
1307                strbuf_reset(&buf);
1308                if (fast_forward != FF_ONLY &&
1309                    merge_remote_util(commit) &&
1310                    merge_remote_util(commit)->obj &&
1311                    merge_remote_util(commit)->obj->type == OBJ_TAG)
1312                        fast_forward = FF_NO;
1313        }
1314
1315        if (option_edit < 0)
1316                option_edit = default_edit_option();
1317
1318        if (!use_strategies) {
1319                if (!remoteheads)
1320                        ; /* already up-to-date */
1321                else if (!remoteheads->next)
1322                        add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1323                else
1324                        add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1325        }
1326
1327        for (i = 0; i < use_strategies_nr; i++) {
1328                if (use_strategies[i]->attr & NO_FAST_FORWARD)
1329                        fast_forward = FF_NO;
1330                if (use_strategies[i]->attr & NO_TRIVIAL)
1331                        allow_trivial = 0;
1332        }
1333
1334        if (!remoteheads)
1335                ; /* already up-to-date */
1336        else if (!remoteheads->next)
1337                common = get_merge_bases(head_commit, remoteheads->item, 1);
1338        else {
1339                struct commit_list *list = remoteheads;
1340                commit_list_insert(head_commit, &list);
1341                common = get_octopus_merge_bases(list);
1342                free(list);
1343        }
1344
1345        update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.sha1,
1346                   NULL, 0, DIE_ON_ERR);
1347
1348        if (remoteheads && !common)
1349                ; /* No common ancestors found. We need a real merge. */
1350        else if (!remoteheads ||
1351                 (!remoteheads->next && !common->next &&
1352                  common->item == remoteheads->item)) {
1353                /*
1354                 * If head can reach all the merge then we are up to date.
1355                 * but first the most common case of merging one remote.
1356                 */
1357                finish_up_to_date("Already up-to-date.");
1358                goto done;
1359        } else if (fast_forward != FF_NO && !remoteheads->next &&
1360                        !common->next &&
1361                        !hashcmp(common->item->object.sha1, head_commit->object.sha1)) {
1362                /* Again the most common case of merging one remote. */
1363                struct strbuf msg = STRBUF_INIT;
1364                struct commit *commit;
1365                char hex[41];
1366
1367                strcpy(hex, find_unique_abbrev(head_commit->object.sha1, DEFAULT_ABBREV));
1368
1369                if (verbosity >= 0)
1370                        printf(_("Updating %s..%s\n"),
1371                                hex,
1372                                find_unique_abbrev(remoteheads->item->object.sha1,
1373                                DEFAULT_ABBREV));
1374                strbuf_addstr(&msg, "Fast-forward");
1375                if (have_message)
1376                        strbuf_addstr(&msg,
1377                                " (no commit created; -m option ignored)");
1378                commit = remoteheads->item;
1379                if (!commit) {
1380                        ret = 1;
1381                        goto done;
1382                }
1383
1384                if (checkout_fast_forward(head_commit->object.sha1,
1385                                          commit->object.sha1,
1386                                          overwrite_ignore)) {
1387                        ret = 1;
1388                        goto done;
1389                }
1390
1391                finish(head_commit, remoteheads, commit->object.sha1, msg.buf);
1392                drop_save();
1393                goto done;
1394        } else if (!remoteheads->next && common->next)
1395                ;
1396                /*
1397                 * We are not doing octopus and not fast-forward.  Need
1398                 * a real merge.
1399                 */
1400        else if (!remoteheads->next && !common->next && option_commit) {
1401                /*
1402                 * We are not doing octopus, not fast-forward, and have
1403                 * only one common.
1404                 */
1405                refresh_cache(REFRESH_QUIET);
1406                if (allow_trivial && fast_forward != FF_ONLY) {
1407                        /* See if it is really trivial. */
1408                        git_committer_info(IDENT_STRICT);
1409                        printf(_("Trying really trivial in-index merge...\n"));
1410                        if (!read_tree_trivial(common->item->object.sha1,
1411                                               head_commit->object.sha1,
1412                                               remoteheads->item->object.sha1)) {
1413                                ret = merge_trivial(head_commit, remoteheads);
1414                                goto done;
1415                        }
1416                        printf(_("Nope.\n"));
1417                }
1418        } else {
1419                /*
1420                 * An octopus.  If we can reach all the remote we are up
1421                 * to date.
1422                 */
1423                int up_to_date = 1;
1424                struct commit_list *j;
1425
1426                for (j = remoteheads; j; j = j->next) {
1427                        struct commit_list *common_one;
1428
1429                        /*
1430                         * Here we *have* to calculate the individual
1431                         * merge_bases again, otherwise "git merge HEAD^
1432                         * HEAD^^" would be missed.
1433                         */
1434                        common_one = get_merge_bases(head_commit, j->item, 1);
1435                        if (hashcmp(common_one->item->object.sha1,
1436                                j->item->object.sha1)) {
1437                                up_to_date = 0;
1438                                break;
1439                        }
1440                }
1441                if (up_to_date) {
1442                        finish_up_to_date("Already up-to-date. Yeeah!");
1443                        goto done;
1444                }
1445        }
1446
1447        if (fast_forward == FF_ONLY)
1448                die(_("Not possible to fast-forward, aborting."));
1449
1450        /* We are going to make a new commit. */
1451        git_committer_info(IDENT_STRICT);
1452
1453        /*
1454         * At this point, we need a real merge.  No matter what strategy
1455         * we use, it would operate on the index, possibly affecting the
1456         * working tree, and when resolved cleanly, have the desired
1457         * tree in the index -- this means that the index must be in
1458         * sync with the head commit.  The strategies are responsible
1459         * to ensure this.
1460         */
1461        if (use_strategies_nr == 1 ||
1462            /*
1463             * Stash away the local changes so that we can try more than one.
1464             */
1465            save_state(stash))
1466                hashcpy(stash, null_sha1);
1467
1468        for (i = 0; i < use_strategies_nr; i++) {
1469                int ret;
1470                if (i) {
1471                        printf(_("Rewinding the tree to pristine...\n"));
1472                        restore_state(head_commit->object.sha1, stash);
1473                }
1474                if (use_strategies_nr != 1)
1475                        printf(_("Trying merge strategy %s...\n"),
1476                                use_strategies[i]->name);
1477                /*
1478                 * Remember which strategy left the state in the working
1479                 * tree.
1480                 */
1481                wt_strategy = use_strategies[i]->name;
1482
1483                ret = try_merge_strategy(use_strategies[i]->name,
1484                                         common, remoteheads,
1485                                         head_commit, head_arg);
1486                if (!option_commit && !ret) {
1487                        merge_was_ok = 1;
1488                        /*
1489                         * This is necessary here just to avoid writing
1490                         * the tree, but later we will *not* exit with
1491                         * status code 1 because merge_was_ok is set.
1492                         */
1493                        ret = 1;
1494                }
1495
1496                if (ret) {
1497                        /*
1498                         * The backend exits with 1 when conflicts are
1499                         * left to be resolved, with 2 when it does not
1500                         * handle the given merge at all.
1501                         */
1502                        if (ret == 1) {
1503                                int cnt = evaluate_result();
1504
1505                                if (best_cnt <= 0 || cnt <= best_cnt) {
1506                                        best_strategy = use_strategies[i]->name;
1507                                        best_cnt = cnt;
1508                                }
1509                        }
1510                        if (merge_was_ok)
1511                                break;
1512                        else
1513                                continue;
1514                }
1515
1516                /* Automerge succeeded. */
1517                write_tree_trivial(result_tree);
1518                automerge_was_ok = 1;
1519                break;
1520        }
1521
1522        /*
1523         * If we have a resulting tree, that means the strategy module
1524         * auto resolved the merge cleanly.
1525         */
1526        if (automerge_was_ok) {
1527                ret = finish_automerge(head_commit, head_subsumed,
1528                                       common, remoteheads,
1529                                       result_tree, wt_strategy);
1530                goto done;
1531        }
1532
1533        /*
1534         * Pick the result from the best strategy and have the user fix
1535         * it up.
1536         */
1537        if (!best_strategy) {
1538                restore_state(head_commit->object.sha1, stash);
1539                if (use_strategies_nr > 1)
1540                        fprintf(stderr,
1541                                _("No merge strategy handled the merge.\n"));
1542                else
1543                        fprintf(stderr, _("Merge with strategy %s failed.\n"),
1544                                use_strategies[0]->name);
1545                ret = 2;
1546                goto done;
1547        } else if (best_strategy == wt_strategy)
1548                ; /* We already have its result in the working tree. */
1549        else {
1550                printf(_("Rewinding the tree to pristine...\n"));
1551                restore_state(head_commit->object.sha1, stash);
1552                printf(_("Using the %s to prepare resolving by hand.\n"),
1553                        best_strategy);
1554                try_merge_strategy(best_strategy, common, remoteheads,
1555                                   head_commit, head_arg);
1556        }
1557
1558        if (squash)
1559                finish(head_commit, remoteheads, NULL, NULL);
1560        else
1561                write_merge_state(remoteheads);
1562
1563        if (merge_was_ok)
1564                fprintf(stderr, _("Automatic merge went well; "
1565                        "stopped before committing as requested\n"));
1566        else
1567                ret = suggest_conflicts(option_renormalize);
1568
1569done:
1570        free(branch_to_free);
1571        return ret;
1572}