builtin / merge.con commit sha1-file.c: mark more strings for translation (259328b)
   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 "config.h"
  11#include "parse-options.h"
  12#include "builtin.h"
  13#include "lockfile.h"
  14#include "run-command.h"
  15#include "diff.h"
  16#include "refs.h"
  17#include "refspec.h"
  18#include "commit.h"
  19#include "diffcore.h"
  20#include "revision.h"
  21#include "unpack-trees.h"
  22#include "cache-tree.h"
  23#include "dir.h"
  24#include "utf8.h"
  25#include "log-tree.h"
  26#include "color.h"
  27#include "rerere.h"
  28#include "help.h"
  29#include "merge-recursive.h"
  30#include "resolve-undo.h"
  31#include "remote.h"
  32#include "fmt-merge-msg.h"
  33#include "gpg-interface.h"
  34#include "sequencer.h"
  35#include "string-list.h"
  36#include "packfile.h"
  37#include "tag.h"
  38#include "alias.h"
  39
  40#define DEFAULT_TWOHEAD (1<<0)
  41#define DEFAULT_OCTOPUS (1<<1)
  42#define NO_FAST_FORWARD (1<<2)
  43#define NO_TRIVIAL      (1<<3)
  44
  45struct strategy {
  46        const char *name;
  47        unsigned attr;
  48};
  49
  50static const char * const builtin_merge_usage[] = {
  51        N_("git merge [<options>] [<commit>...]"),
  52        N_("git merge --abort"),
  53        N_("git merge --continue"),
  54        NULL
  55};
  56
  57static int show_diffstat = 1, shortlog_len = -1, squash;
  58static int option_commit = 1;
  59static int option_edit = -1;
  60static int allow_trivial = 1, have_message, verify_signatures;
  61static int overwrite_ignore = 1;
  62static struct strbuf merge_msg = STRBUF_INIT;
  63static struct strategy **use_strategies;
  64static size_t use_strategies_nr, use_strategies_alloc;
  65static const char **xopts;
  66static size_t xopts_nr, xopts_alloc;
  67static const char *branch;
  68static char *branch_mergeoptions;
  69static int option_renormalize;
  70static int verbosity;
  71static int allow_rerere_auto;
  72static int abort_current_merge;
  73static int continue_current_merge;
  74static int allow_unrelated_histories;
  75static int show_progress = -1;
  76static int default_to_upstream = 1;
  77static int signoff;
  78static const char *sign_commit;
  79static int verify_msg = 1;
  80
  81static struct strategy all_strategy[] = {
  82        { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
  83        { "octopus",    DEFAULT_OCTOPUS },
  84        { "resolve",    0 },
  85        { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
  86        { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
  87};
  88
  89static const char *pull_twohead, *pull_octopus;
  90
  91enum ff_type {
  92        FF_NO,
  93        FF_ALLOW,
  94        FF_ONLY
  95};
  96
  97static enum ff_type fast_forward = FF_ALLOW;
  98
  99static int option_parse_message(const struct option *opt,
 100                                const char *arg, int unset)
 101{
 102        struct strbuf *buf = opt->value;
 103
 104        if (unset)
 105                strbuf_setlen(buf, 0);
 106        else if (arg) {
 107                strbuf_addf(buf, "%s%s", buf->len ? "\n\n" : "", arg);
 108                have_message = 1;
 109        } else
 110                return error(_("switch `m' requires a value"));
 111        return 0;
 112}
 113
 114static struct strategy *get_strategy(const char *name)
 115{
 116        int i;
 117        struct strategy *ret;
 118        static struct cmdnames main_cmds, other_cmds;
 119        static int loaded;
 120
 121        if (!name)
 122                return NULL;
 123
 124        for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 125                if (!strcmp(name, all_strategy[i].name))
 126                        return &all_strategy[i];
 127
 128        if (!loaded) {
 129                struct cmdnames not_strategies;
 130                loaded = 1;
 131
 132                memset(&not_strategies, 0, sizeof(struct cmdnames));
 133                load_command_list("git-merge-", &main_cmds, &other_cmds);
 134                for (i = 0; i < main_cmds.cnt; i++) {
 135                        int j, found = 0;
 136                        struct cmdname *ent = main_cmds.names[i];
 137                        for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
 138                                if (!strncmp(ent->name, all_strategy[j].name, ent->len)
 139                                                && !all_strategy[j].name[ent->len])
 140                                        found = 1;
 141                        if (!found)
 142                                add_cmdname(&not_strategies, ent->name, ent->len);
 143                }
 144                exclude_cmds(&main_cmds, &not_strategies);
 145        }
 146        if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
 147                fprintf(stderr, _("Could not find merge strategy '%s'.\n"), name);
 148                fprintf(stderr, _("Available strategies are:"));
 149                for (i = 0; i < main_cmds.cnt; i++)
 150                        fprintf(stderr, " %s", main_cmds.names[i]->name);
 151                fprintf(stderr, ".\n");
 152                if (other_cmds.cnt) {
 153                        fprintf(stderr, _("Available custom strategies are:"));
 154                        for (i = 0; i < other_cmds.cnt; i++)
 155                                fprintf(stderr, " %s", other_cmds.names[i]->name);
 156                        fprintf(stderr, ".\n");
 157                }
 158                exit(1);
 159        }
 160
 161        ret = xcalloc(1, sizeof(struct strategy));
 162        ret->name = xstrdup(name);
 163        ret->attr = NO_TRIVIAL;
 164        return ret;
 165}
 166
 167static void append_strategy(struct strategy *s)
 168{
 169        ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
 170        use_strategies[use_strategies_nr++] = s;
 171}
 172
 173static int option_parse_strategy(const struct option *opt,
 174                                 const char *name, int unset)
 175{
 176        if (unset)
 177                return 0;
 178
 179        append_strategy(get_strategy(name));
 180        return 0;
 181}
 182
 183static int option_parse_x(const struct option *opt,
 184                          const char *arg, int unset)
 185{
 186        if (unset)
 187                return 0;
 188
 189        ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
 190        xopts[xopts_nr++] = xstrdup(arg);
 191        return 0;
 192}
 193
 194static int option_parse_n(const struct option *opt,
 195                          const char *arg, int unset)
 196{
 197        show_diffstat = unset;
 198        return 0;
 199}
 200
 201static struct option builtin_merge_options[] = {
 202        { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
 203                N_("do not show a diffstat at the end of the merge"),
 204                PARSE_OPT_NOARG, option_parse_n },
 205        OPT_BOOL(0, "stat", &show_diffstat,
 206                N_("show a diffstat at the end of the merge")),
 207        OPT_BOOL(0, "summary", &show_diffstat, N_("(synonym to --stat)")),
 208        { OPTION_INTEGER, 0, "log", &shortlog_len, N_("n"),
 209          N_("add (at most <n>) entries from shortlog to merge commit message"),
 210          PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
 211        OPT_BOOL(0, "squash", &squash,
 212                N_("create a single commit instead of doing a merge")),
 213        OPT_BOOL(0, "commit", &option_commit,
 214                N_("perform a commit if the merge succeeds (default)")),
 215        OPT_BOOL('e', "edit", &option_edit,
 216                N_("edit message before committing")),
 217        OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
 218        OPT_SET_INT_F(0, "ff-only", &fast_forward,
 219                      N_("abort if fast-forward is not possible"),
 220                      FF_ONLY, PARSE_OPT_NONEG),
 221        OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
 222        OPT_BOOL(0, "verify-signatures", &verify_signatures,
 223                N_("verify that the named commit has a valid GPG signature")),
 224        OPT_CALLBACK('s', "strategy", &use_strategies, N_("strategy"),
 225                N_("merge strategy to use"), option_parse_strategy),
 226        OPT_CALLBACK('X', "strategy-option", &xopts, N_("option=value"),
 227                N_("option for selected merge strategy"), option_parse_x),
 228        OPT_CALLBACK('m', "message", &merge_msg, N_("message"),
 229                N_("merge commit message (for a non-fast-forward merge)"),
 230                option_parse_message),
 231        OPT__VERBOSITY(&verbosity),
 232        OPT_BOOL(0, "abort", &abort_current_merge,
 233                N_("abort the current in-progress merge")),
 234        OPT_BOOL(0, "continue", &continue_current_merge,
 235                N_("continue the current in-progress merge")),
 236        OPT_BOOL(0, "allow-unrelated-histories", &allow_unrelated_histories,
 237                 N_("allow merging unrelated histories")),
 238        OPT_SET_INT(0, "progress", &show_progress, N_("force progress reporting"), 1),
 239        { OPTION_STRING, 'S', "gpg-sign", &sign_commit, N_("key-id"),
 240          N_("GPG sign commit"), PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
 241        OPT_BOOL(0, "overwrite-ignore", &overwrite_ignore, N_("update ignored files (default)")),
 242        OPT_BOOL(0, "signoff", &signoff, N_("add Signed-off-by:")),
 243        OPT_BOOL(0, "verify", &verify_msg, N_("verify commit-msg hook")),
 244        OPT_END()
 245};
 246
 247/* Cleans up metadata that is uninteresting after a succeeded merge. */
 248static void drop_save(void)
 249{
 250        unlink(git_path_merge_head());
 251        unlink(git_path_merge_msg());
 252        unlink(git_path_merge_mode());
 253}
 254
 255static int save_state(struct object_id *stash)
 256{
 257        int len;
 258        struct child_process cp = CHILD_PROCESS_INIT;
 259        struct strbuf buffer = STRBUF_INIT;
 260        const char *argv[] = {"stash", "create", NULL};
 261        int rc = -1;
 262
 263        cp.argv = argv;
 264        cp.out = -1;
 265        cp.git_cmd = 1;
 266
 267        if (start_command(&cp))
 268                die(_("could not run stash."));
 269        len = strbuf_read(&buffer, cp.out, 1024);
 270        close(cp.out);
 271
 272        if (finish_command(&cp) || len < 0)
 273                die(_("stash failed"));
 274        else if (!len)          /* no changes */
 275                goto out;
 276        strbuf_setlen(&buffer, buffer.len-1);
 277        if (get_oid(buffer.buf, stash))
 278                die(_("not a valid object: %s"), buffer.buf);
 279        rc = 0;
 280out:
 281        strbuf_release(&buffer);
 282        return rc;
 283}
 284
 285static void read_empty(const struct object_id *oid, int verbose)
 286{
 287        int i = 0;
 288        const char *args[7];
 289
 290        args[i++] = "read-tree";
 291        if (verbose)
 292                args[i++] = "-v";
 293        args[i++] = "-m";
 294        args[i++] = "-u";
 295        args[i++] = empty_tree_oid_hex();
 296        args[i++] = oid_to_hex(oid);
 297        args[i] = NULL;
 298
 299        if (run_command_v_opt(args, RUN_GIT_CMD))
 300                die(_("read-tree failed"));
 301}
 302
 303static void reset_hard(const struct object_id *oid, int verbose)
 304{
 305        int i = 0;
 306        const char *args[6];
 307
 308        args[i++] = "read-tree";
 309        if (verbose)
 310                args[i++] = "-v";
 311        args[i++] = "--reset";
 312        args[i++] = "-u";
 313        args[i++] = oid_to_hex(oid);
 314        args[i] = NULL;
 315
 316        if (run_command_v_opt(args, RUN_GIT_CMD))
 317                die(_("read-tree failed"));
 318}
 319
 320static void restore_state(const struct object_id *head,
 321                          const struct object_id *stash)
 322{
 323        struct strbuf sb = STRBUF_INIT;
 324        const char *args[] = { "stash", "apply", NULL, NULL };
 325
 326        if (is_null_oid(stash))
 327                return;
 328
 329        reset_hard(head, 1);
 330
 331        args[2] = oid_to_hex(stash);
 332
 333        /*
 334         * It is OK to ignore error here, for example when there was
 335         * nothing to restore.
 336         */
 337        run_command_v_opt(args, RUN_GIT_CMD);
 338
 339        strbuf_release(&sb);
 340        refresh_cache(REFRESH_QUIET);
 341}
 342
 343/* This is called when no merge was necessary. */
 344static void finish_up_to_date(const char *msg)
 345{
 346        if (verbosity >= 0)
 347                printf("%s%s\n", squash ? _(" (nothing to squash)") : "", msg);
 348        drop_save();
 349}
 350
 351static void squash_message(struct commit *commit, struct commit_list *remoteheads)
 352{
 353        struct rev_info rev;
 354        struct strbuf out = STRBUF_INIT;
 355        struct commit_list *j;
 356        struct pretty_print_context ctx = {0};
 357
 358        printf(_("Squash commit -- not updating HEAD\n"));
 359
 360        init_revisions(&rev, NULL);
 361        rev.ignore_merges = 1;
 362        rev.commit_format = CMIT_FMT_MEDIUM;
 363
 364        commit->object.flags |= UNINTERESTING;
 365        add_pending_object(&rev, &commit->object, NULL);
 366
 367        for (j = remoteheads; j; j = j->next)
 368                add_pending_object(&rev, &j->item->object, NULL);
 369
 370        setup_revisions(0, NULL, &rev, NULL);
 371        if (prepare_revision_walk(&rev))
 372                die(_("revision walk setup failed"));
 373
 374        ctx.abbrev = rev.abbrev;
 375        ctx.date_mode = rev.date_mode;
 376        ctx.fmt = rev.commit_format;
 377
 378        strbuf_addstr(&out, "Squashed commit of the following:\n");
 379        while ((commit = get_revision(&rev)) != NULL) {
 380                strbuf_addch(&out, '\n');
 381                strbuf_addf(&out, "commit %s\n",
 382                        oid_to_hex(&commit->object.oid));
 383                pretty_print_commit(&ctx, commit, &out);
 384        }
 385        write_file_buf(git_path_squash_msg(), out.buf, out.len);
 386        strbuf_release(&out);
 387}
 388
 389static void finish(struct commit *head_commit,
 390                   struct commit_list *remoteheads,
 391                   const struct object_id *new_head, const char *msg)
 392{
 393        struct strbuf reflog_message = STRBUF_INIT;
 394        const struct object_id *head = &head_commit->object.oid;
 395
 396        if (!msg)
 397                strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
 398        else {
 399                if (verbosity >= 0)
 400                        printf("%s\n", msg);
 401                strbuf_addf(&reflog_message, "%s: %s",
 402                        getenv("GIT_REFLOG_ACTION"), msg);
 403        }
 404        if (squash) {
 405                squash_message(head_commit, remoteheads);
 406        } else {
 407                if (verbosity >= 0 && !merge_msg.len)
 408                        printf(_("No merge message -- not updating HEAD\n"));
 409                else {
 410                        const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 411                        update_ref(reflog_message.buf, "HEAD", new_head, head,
 412                                   0, UPDATE_REFS_DIE_ON_ERR);
 413                        /*
 414                         * We ignore errors in 'gc --auto', since the
 415                         * user should see them.
 416                         */
 417                        close_all_packs(the_repository->objects);
 418                        run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 419                }
 420        }
 421        if (new_head && show_diffstat) {
 422                struct diff_options opts;
 423                diff_setup(&opts);
 424                opts.stat_width = -1; /* use full terminal width */
 425                opts.stat_graph_width = -1; /* respect statGraphWidth config */
 426                opts.output_format |=
 427                        DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 428                opts.detect_rename = DIFF_DETECT_RENAME;
 429                diff_setup_done(&opts);
 430                diff_tree_oid(head, new_head, "", &opts);
 431                diffcore_std(&opts);
 432                diff_flush(&opts);
 433        }
 434
 435        /* Run a post-merge hook */
 436        run_hook_le(NULL, "post-merge", squash ? "1" : "0", NULL);
 437
 438        strbuf_release(&reflog_message);
 439}
 440
 441/* Get the name for the merge commit's message. */
 442static void merge_name(const char *remote, struct strbuf *msg)
 443{
 444        struct commit *remote_head;
 445        struct object_id branch_head;
 446        struct strbuf buf = STRBUF_INIT;
 447        struct strbuf bname = STRBUF_INIT;
 448        struct merge_remote_desc *desc;
 449        const char *ptr;
 450        char *found_ref;
 451        int len, early;
 452
 453        strbuf_branchname(&bname, remote, 0);
 454        remote = bname.buf;
 455
 456        oidclr(&branch_head);
 457        remote_head = get_merge_parent(remote);
 458        if (!remote_head)
 459                die(_("'%s' does not point to a commit"), remote);
 460
 461        if (dwim_ref(remote, strlen(remote), &branch_head, &found_ref) > 0) {
 462                if (starts_with(found_ref, "refs/heads/")) {
 463                        strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 464                                    oid_to_hex(&branch_head), remote);
 465                        goto cleanup;
 466                }
 467                if (starts_with(found_ref, "refs/tags/")) {
 468                        strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
 469                                    oid_to_hex(&branch_head), remote);
 470                        goto cleanup;
 471                }
 472                if (starts_with(found_ref, "refs/remotes/")) {
 473                        strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
 474                                    oid_to_hex(&branch_head), remote);
 475                        goto cleanup;
 476                }
 477        }
 478
 479        /* See if remote matches <name>^^^.. or <name>~<number> */
 480        for (len = 0, ptr = remote + strlen(remote);
 481             remote < ptr && ptr[-1] == '^';
 482             ptr--)
 483                len++;
 484        if (len)
 485                early = 1;
 486        else {
 487                early = 0;
 488                ptr = strrchr(remote, '~');
 489                if (ptr) {
 490                        int seen_nonzero = 0;
 491
 492                        len++; /* count ~ */
 493                        while (*++ptr && isdigit(*ptr)) {
 494                                seen_nonzero |= (*ptr != '0');
 495                                len++;
 496                        }
 497                        if (*ptr)
 498                                len = 0; /* not ...~<number> */
 499                        else if (seen_nonzero)
 500                                early = 1;
 501                        else if (len == 1)
 502                                early = 1; /* "name~" is "name~1"! */
 503                }
 504        }
 505        if (len) {
 506                struct strbuf truname = STRBUF_INIT;
 507                strbuf_addf(&truname, "refs/heads/%s", remote);
 508                strbuf_setlen(&truname, truname.len - len);
 509                if (ref_exists(truname.buf)) {
 510                        strbuf_addf(msg,
 511                                    "%s\t\tbranch '%s'%s of .\n",
 512                                    oid_to_hex(&remote_head->object.oid),
 513                                    truname.buf + 11,
 514                                    (early ? " (early part)" : ""));
 515                        strbuf_release(&truname);
 516                        goto cleanup;
 517                }
 518                strbuf_release(&truname);
 519        }
 520
 521        desc = merge_remote_util(remote_head);
 522        if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
 523                strbuf_addf(msg, "%s\t\t%s '%s'\n",
 524                            oid_to_hex(&desc->obj->oid),
 525                            type_name(desc->obj->type),
 526                            remote);
 527                goto cleanup;
 528        }
 529
 530        strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 531                oid_to_hex(&remote_head->object.oid), remote);
 532cleanup:
 533        strbuf_release(&buf);
 534        strbuf_release(&bname);
 535}
 536
 537static void parse_branch_merge_options(char *bmo)
 538{
 539        const char **argv;
 540        int argc;
 541
 542        if (!bmo)
 543                return;
 544        argc = split_cmdline(bmo, &argv);
 545        if (argc < 0)
 546                die(_("Bad branch.%s.mergeoptions string: %s"), branch,
 547                    split_cmdline_strerror(argc));
 548        REALLOC_ARRAY(argv, argc + 2);
 549        MOVE_ARRAY(argv + 1, argv, argc + 1);
 550        argc++;
 551        argv[0] = "branch.*.mergeoptions";
 552        parse_options(argc, argv, NULL, builtin_merge_options,
 553                      builtin_merge_usage, 0);
 554        free(argv);
 555}
 556
 557static int git_merge_config(const char *k, const char *v, void *cb)
 558{
 559        int status;
 560
 561        if (branch && starts_with(k, "branch.") &&
 562                starts_with(k + 7, branch) &&
 563                !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
 564                free(branch_mergeoptions);
 565                branch_mergeoptions = xstrdup(v);
 566                return 0;
 567        }
 568
 569        if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 570                show_diffstat = git_config_bool(k, v);
 571        else if (!strcmp(k, "merge.verifysignatures"))
 572                verify_signatures = git_config_bool(k, v);
 573        else if (!strcmp(k, "pull.twohead"))
 574                return git_config_string(&pull_twohead, k, v);
 575        else if (!strcmp(k, "pull.octopus"))
 576                return git_config_string(&pull_octopus, k, v);
 577        else if (!strcmp(k, "merge.renormalize"))
 578                option_renormalize = git_config_bool(k, v);
 579        else if (!strcmp(k, "merge.ff")) {
 580                int boolval = git_parse_maybe_bool(v);
 581                if (0 <= boolval) {
 582                        fast_forward = boolval ? FF_ALLOW : FF_NO;
 583                } else if (v && !strcmp(v, "only")) {
 584                        fast_forward = FF_ONLY;
 585                } /* do not barf on values from future versions of git */
 586                return 0;
 587        } else if (!strcmp(k, "merge.defaulttoupstream")) {
 588                default_to_upstream = git_config_bool(k, v);
 589                return 0;
 590        } else if (!strcmp(k, "commit.gpgsign")) {
 591                sign_commit = git_config_bool(k, v) ? "" : NULL;
 592                return 0;
 593        }
 594
 595        status = fmt_merge_msg_config(k, v, cb);
 596        if (status)
 597                return status;
 598        status = git_gpg_config(k, v, NULL);
 599        if (status)
 600                return status;
 601        return git_diff_ui_config(k, v, cb);
 602}
 603
 604static int read_tree_trivial(struct object_id *common, struct object_id *head,
 605                             struct object_id *one)
 606{
 607        int i, nr_trees = 0;
 608        struct tree *trees[MAX_UNPACK_TREES];
 609        struct tree_desc t[MAX_UNPACK_TREES];
 610        struct unpack_trees_options opts;
 611
 612        memset(&opts, 0, sizeof(opts));
 613        opts.head_idx = 2;
 614        opts.src_index = &the_index;
 615        opts.dst_index = &the_index;
 616        opts.update = 1;
 617        opts.verbose_update = 1;
 618        opts.trivial_merges_only = 1;
 619        opts.merge = 1;
 620        trees[nr_trees] = parse_tree_indirect(common);
 621        if (!trees[nr_trees++])
 622                return -1;
 623        trees[nr_trees] = parse_tree_indirect(head);
 624        if (!trees[nr_trees++])
 625                return -1;
 626        trees[nr_trees] = parse_tree_indirect(one);
 627        if (!trees[nr_trees++])
 628                return -1;
 629        opts.fn = threeway_merge;
 630        cache_tree_free(&active_cache_tree);
 631        for (i = 0; i < nr_trees; i++) {
 632                parse_tree(trees[i]);
 633                init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 634        }
 635        if (unpack_trees(nr_trees, t, &opts))
 636                return -1;
 637        return 0;
 638}
 639
 640static void write_tree_trivial(struct object_id *oid)
 641{
 642        if (write_cache_as_tree(oid, 0, NULL))
 643                die(_("git write-tree failed to write a tree"));
 644}
 645
 646static int try_merge_strategy(const char *strategy, struct commit_list *common,
 647                              struct commit_list *remoteheads,
 648                              struct commit *head)
 649{
 650        struct lock_file lock = LOCK_INIT;
 651        const char *head_arg = "HEAD";
 652
 653        hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
 654        refresh_cache(REFRESH_QUIET);
 655        if (write_locked_index(&the_index, &lock,
 656                               COMMIT_LOCK | SKIP_IF_UNCHANGED))
 657                return error(_("Unable to write index."));
 658
 659        if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
 660                int clean, x;
 661                struct commit *result;
 662                struct commit_list *reversed = NULL;
 663                struct merge_options o;
 664                struct commit_list *j;
 665
 666                if (remoteheads->next) {
 667                        error(_("Not handling anything other than two heads merge."));
 668                        return 2;
 669                }
 670
 671                init_merge_options(&o);
 672                if (!strcmp(strategy, "subtree"))
 673                        o.subtree_shift = "";
 674
 675                o.renormalize = option_renormalize;
 676                o.show_rename_progress =
 677                        show_progress == -1 ? isatty(2) : show_progress;
 678
 679                for (x = 0; x < xopts_nr; x++)
 680                        if (parse_merge_opt(&o, xopts[x]))
 681                                die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
 682
 683                o.branch1 = head_arg;
 684                o.branch2 = merge_remote_util(remoteheads->item)->name;
 685
 686                for (j = common; j; j = j->next)
 687                        commit_list_insert(j->item, &reversed);
 688
 689                hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
 690                clean = merge_recursive(&o, head,
 691                                remoteheads->item, reversed, &result);
 692                if (clean < 0)
 693                        exit(128);
 694                if (write_locked_index(&the_index, &lock,
 695                                       COMMIT_LOCK | SKIP_IF_UNCHANGED))
 696                        die(_("unable to write %s"), get_index_file());
 697                return clean ? 0 : 1;
 698        } else {
 699                return try_merge_command(strategy, xopts_nr, xopts,
 700                                                common, head_arg, remoteheads);
 701        }
 702}
 703
 704static void count_diff_files(struct diff_queue_struct *q,
 705                             struct diff_options *opt, void *data)
 706{
 707        int *count = data;
 708
 709        (*count) += q->nr;
 710}
 711
 712static int count_unmerged_entries(void)
 713{
 714        int i, ret = 0;
 715
 716        for (i = 0; i < active_nr; i++)
 717                if (ce_stage(active_cache[i]))
 718                        ret++;
 719
 720        return ret;
 721}
 722
 723static void add_strategies(const char *string, unsigned attr)
 724{
 725        int i;
 726
 727        if (string) {
 728                struct string_list list = STRING_LIST_INIT_DUP;
 729                struct string_list_item *item;
 730                string_list_split(&list, string, ' ', -1);
 731                for_each_string_list_item(item, &list)
 732                        append_strategy(get_strategy(item->string));
 733                string_list_clear(&list, 0);
 734                return;
 735        }
 736        for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 737                if (all_strategy[i].attr & attr)
 738                        append_strategy(&all_strategy[i]);
 739
 740}
 741
 742static void read_merge_msg(struct strbuf *msg)
 743{
 744        const char *filename = git_path_merge_msg();
 745        strbuf_reset(msg);
 746        if (strbuf_read_file(msg, filename, 0) < 0)
 747                die_errno(_("Could not read from '%s'"), filename);
 748}
 749
 750static void write_merge_state(struct commit_list *);
 751static void abort_commit(struct commit_list *remoteheads, const char *err_msg)
 752{
 753        if (err_msg)
 754                error("%s", err_msg);
 755        fprintf(stderr,
 756                _("Not committing merge; use 'git commit' to complete the merge.\n"));
 757        write_merge_state(remoteheads);
 758        exit(1);
 759}
 760
 761static const char merge_editor_comment[] =
 762N_("Please enter a commit message to explain why this merge is necessary,\n"
 763   "especially if it merges an updated upstream into a topic branch.\n"
 764   "\n"
 765   "Lines starting with '%c' will be ignored, and an empty message aborts\n"
 766   "the commit.\n");
 767
 768static void write_merge_heads(struct commit_list *);
 769static void prepare_to_commit(struct commit_list *remoteheads)
 770{
 771        struct strbuf msg = STRBUF_INIT;
 772        strbuf_addbuf(&msg, &merge_msg);
 773        strbuf_addch(&msg, '\n');
 774        if (squash)
 775                BUG("the control must not reach here under --squash");
 776        if (0 < option_edit)
 777                strbuf_commented_addf(&msg, _(merge_editor_comment), comment_line_char);
 778        if (signoff)
 779                append_signoff(&msg, ignore_non_trailer(msg.buf, msg.len), 0);
 780        write_merge_heads(remoteheads);
 781        write_file_buf(git_path_merge_msg(), msg.buf, msg.len);
 782        if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
 783                            git_path_merge_msg(), "merge", NULL))
 784                abort_commit(remoteheads, NULL);
 785        if (0 < option_edit) {
 786                if (launch_editor(git_path_merge_msg(), NULL, NULL))
 787                        abort_commit(remoteheads, NULL);
 788        }
 789
 790        if (verify_msg && run_commit_hook(0 < option_edit, get_index_file(),
 791                                          "commit-msg",
 792                                          git_path_merge_msg(), NULL))
 793                abort_commit(remoteheads, NULL);
 794
 795        read_merge_msg(&msg);
 796        strbuf_stripspace(&msg, 0 < option_edit);
 797        if (!msg.len)
 798                abort_commit(remoteheads, _("Empty commit message."));
 799        strbuf_release(&merge_msg);
 800        strbuf_addbuf(&merge_msg, &msg);
 801        strbuf_release(&msg);
 802}
 803
 804static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
 805{
 806        struct object_id result_tree, result_commit;
 807        struct commit_list *parents, **pptr = &parents;
 808        struct lock_file lock = LOCK_INIT;
 809
 810        hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
 811        refresh_cache(REFRESH_QUIET);
 812        if (write_locked_index(&the_index, &lock,
 813                               COMMIT_LOCK | SKIP_IF_UNCHANGED))
 814                return error(_("Unable to write index."));
 815
 816        write_tree_trivial(&result_tree);
 817        printf(_("Wonderful.\n"));
 818        pptr = commit_list_append(head, pptr);
 819        pptr = commit_list_append(remoteheads->item, pptr);
 820        prepare_to_commit(remoteheads);
 821        if (commit_tree(merge_msg.buf, merge_msg.len, &result_tree, parents,
 822                        &result_commit, NULL, sign_commit))
 823                die(_("failed to write commit object"));
 824        finish(head, remoteheads, &result_commit, "In-index merge");
 825        drop_save();
 826        return 0;
 827}
 828
 829static int finish_automerge(struct commit *head,
 830                            int head_subsumed,
 831                            struct commit_list *common,
 832                            struct commit_list *remoteheads,
 833                            struct object_id *result_tree,
 834                            const char *wt_strategy)
 835{
 836        struct commit_list *parents = NULL;
 837        struct strbuf buf = STRBUF_INIT;
 838        struct object_id result_commit;
 839
 840        free_commit_list(common);
 841        parents = remoteheads;
 842        if (!head_subsumed || fast_forward == FF_NO)
 843                commit_list_insert(head, &parents);
 844        strbuf_addch(&merge_msg, '\n');
 845        prepare_to_commit(remoteheads);
 846        if (commit_tree(merge_msg.buf, merge_msg.len, result_tree, parents,
 847                        &result_commit, NULL, sign_commit))
 848                die(_("failed to write commit object"));
 849        strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
 850        finish(head, remoteheads, &result_commit, buf.buf);
 851        strbuf_release(&buf);
 852        drop_save();
 853        return 0;
 854}
 855
 856static int suggest_conflicts(void)
 857{
 858        const char *filename;
 859        FILE *fp;
 860        struct strbuf msgbuf = STRBUF_INIT;
 861
 862        filename = git_path_merge_msg();
 863        fp = xfopen(filename, "a");
 864
 865        append_conflicts_hint(&msgbuf);
 866        fputs(msgbuf.buf, fp);
 867        strbuf_release(&msgbuf);
 868        fclose(fp);
 869        rerere(allow_rerere_auto);
 870        printf(_("Automatic merge failed; "
 871                        "fix conflicts and then commit the result.\n"));
 872        return 1;
 873}
 874
 875static int evaluate_result(void)
 876{
 877        int cnt = 0;
 878        struct rev_info rev;
 879
 880        /* Check how many files differ. */
 881        init_revisions(&rev, "");
 882        setup_revisions(0, NULL, &rev, NULL);
 883        rev.diffopt.output_format |=
 884                DIFF_FORMAT_CALLBACK;
 885        rev.diffopt.format_callback = count_diff_files;
 886        rev.diffopt.format_callback_data = &cnt;
 887        run_diff_files(&rev, 0);
 888
 889        /*
 890         * Check how many unmerged entries are
 891         * there.
 892         */
 893        cnt += count_unmerged_entries();
 894
 895        return cnt;
 896}
 897
 898/*
 899 * Pretend as if the user told us to merge with the remote-tracking
 900 * branch we have for the upstream of the current branch
 901 */
 902static int setup_with_upstream(const char ***argv)
 903{
 904        struct branch *branch = branch_get(NULL);
 905        int i;
 906        const char **args;
 907
 908        if (!branch)
 909                die(_("No current branch."));
 910        if (!branch->remote_name)
 911                die(_("No remote for the current branch."));
 912        if (!branch->merge_nr)
 913                die(_("No default upstream defined for the current branch."));
 914
 915        args = xcalloc(st_add(branch->merge_nr, 1), sizeof(char *));
 916        for (i = 0; i < branch->merge_nr; i++) {
 917                if (!branch->merge[i]->dst)
 918                        die(_("No remote-tracking branch for %s from %s"),
 919                            branch->merge[i]->src, branch->remote_name);
 920                args[i] = branch->merge[i]->dst;
 921        }
 922        args[i] = NULL;
 923        *argv = args;
 924        return i;
 925}
 926
 927static void write_merge_heads(struct commit_list *remoteheads)
 928{
 929        struct commit_list *j;
 930        struct strbuf buf = STRBUF_INIT;
 931
 932        for (j = remoteheads; j; j = j->next) {
 933                struct object_id *oid;
 934                struct commit *c = j->item;
 935                struct merge_remote_desc *desc;
 936
 937                desc = merge_remote_util(c);
 938                if (desc && desc->obj) {
 939                        oid = &desc->obj->oid;
 940                } else {
 941                        oid = &c->object.oid;
 942                }
 943                strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
 944        }
 945        write_file_buf(git_path_merge_head(), buf.buf, buf.len);
 946
 947        strbuf_reset(&buf);
 948        if (fast_forward == FF_NO)
 949                strbuf_addstr(&buf, "no-ff");
 950        write_file_buf(git_path_merge_mode(), buf.buf, buf.len);
 951        strbuf_release(&buf);
 952}
 953
 954static void write_merge_state(struct commit_list *remoteheads)
 955{
 956        write_merge_heads(remoteheads);
 957        strbuf_addch(&merge_msg, '\n');
 958        write_file_buf(git_path_merge_msg(), merge_msg.buf, merge_msg.len);
 959}
 960
 961static int default_edit_option(void)
 962{
 963        static const char name[] = "GIT_MERGE_AUTOEDIT";
 964        const char *e = getenv(name);
 965        struct stat st_stdin, st_stdout;
 966
 967        if (have_message)
 968                /* an explicit -m msg without --[no-]edit */
 969                return 0;
 970
 971        if (e) {
 972                int v = git_parse_maybe_bool(e);
 973                if (v < 0)
 974                        die(_("Bad value '%s' in environment '%s'"), e, name);
 975                return v;
 976        }
 977
 978        /* Use editor if stdin and stdout are the same and is a tty */
 979        return (!fstat(0, &st_stdin) &&
 980                !fstat(1, &st_stdout) &&
 981                isatty(0) && isatty(1) &&
 982                st_stdin.st_dev == st_stdout.st_dev &&
 983                st_stdin.st_ino == st_stdout.st_ino &&
 984                st_stdin.st_mode == st_stdout.st_mode);
 985}
 986
 987static struct commit_list *reduce_parents(struct commit *head_commit,
 988                                          int *head_subsumed,
 989                                          struct commit_list *remoteheads)
 990{
 991        struct commit_list *parents, **remotes;
 992
 993        /*
 994         * Is the current HEAD reachable from another commit being
 995         * merged?  If so we do not want to record it as a parent of
 996         * the resulting merge, unless --no-ff is given.  We will flip
 997         * this variable to 0 when we find HEAD among the independent
 998         * tips being merged.
 999         */
1000        *head_subsumed = 1;
1001
1002        /* Find what parents to record by checking independent ones. */
1003        parents = reduce_heads(remoteheads);
1004        free_commit_list(remoteheads);
1005
1006        remoteheads = NULL;
1007        remotes = &remoteheads;
1008        while (parents) {
1009                struct commit *commit = pop_commit(&parents);
1010                if (commit == head_commit)
1011                        *head_subsumed = 0;
1012                else
1013                        remotes = &commit_list_insert(commit, remotes)->next;
1014        }
1015        return remoteheads;
1016}
1017
1018static void prepare_merge_message(struct strbuf *merge_names, struct strbuf *merge_msg)
1019{
1020        struct fmt_merge_msg_opts opts;
1021
1022        memset(&opts, 0, sizeof(opts));
1023        opts.add_title = !have_message;
1024        opts.shortlog_len = shortlog_len;
1025        opts.credit_people = (0 < option_edit);
1026
1027        fmt_merge_msg(merge_names, merge_msg, &opts);
1028        if (merge_msg->len)
1029                strbuf_setlen(merge_msg, merge_msg->len - 1);
1030}
1031
1032static void handle_fetch_head(struct commit_list **remotes, struct strbuf *merge_names)
1033{
1034        const char *filename;
1035        int fd, pos, npos;
1036        struct strbuf fetch_head_file = STRBUF_INIT;
1037
1038        if (!merge_names)
1039                merge_names = &fetch_head_file;
1040
1041        filename = git_path_fetch_head();
1042        fd = open(filename, O_RDONLY);
1043        if (fd < 0)
1044                die_errno(_("could not open '%s' for reading"), filename);
1045
1046        if (strbuf_read(merge_names, fd, 0) < 0)
1047                die_errno(_("could not read '%s'"), filename);
1048        if (close(fd) < 0)
1049                die_errno(_("could not close '%s'"), filename);
1050
1051        for (pos = 0; pos < merge_names->len; pos = npos) {
1052                struct object_id oid;
1053                char *ptr;
1054                struct commit *commit;
1055
1056                ptr = strchr(merge_names->buf + pos, '\n');
1057                if (ptr)
1058                        npos = ptr - merge_names->buf + 1;
1059                else
1060                        npos = merge_names->len;
1061
1062                if (npos - pos < GIT_SHA1_HEXSZ + 2 ||
1063                    get_oid_hex(merge_names->buf + pos, &oid))
1064                        commit = NULL; /* bad */
1065                else if (memcmp(merge_names->buf + pos + GIT_SHA1_HEXSZ, "\t\t", 2))
1066                        continue; /* not-for-merge */
1067                else {
1068                        char saved = merge_names->buf[pos + GIT_SHA1_HEXSZ];
1069                        merge_names->buf[pos + GIT_SHA1_HEXSZ] = '\0';
1070                        commit = get_merge_parent(merge_names->buf + pos);
1071                        merge_names->buf[pos + GIT_SHA1_HEXSZ] = saved;
1072                }
1073                if (!commit) {
1074                        if (ptr)
1075                                *ptr = '\0';
1076                        die(_("not something we can merge in %s: %s"),
1077                            filename, merge_names->buf + pos);
1078                }
1079                remotes = &commit_list_insert(commit, remotes)->next;
1080        }
1081
1082        if (merge_names == &fetch_head_file)
1083                strbuf_release(&fetch_head_file);
1084}
1085
1086static struct commit_list *collect_parents(struct commit *head_commit,
1087                                           int *head_subsumed,
1088                                           int argc, const char **argv,
1089                                           struct strbuf *merge_msg)
1090{
1091        int i;
1092        struct commit_list *remoteheads = NULL;
1093        struct commit_list **remotes = &remoteheads;
1094        struct strbuf merge_names = STRBUF_INIT, *autogen = NULL;
1095
1096        if (merge_msg && (!have_message || shortlog_len))
1097                autogen = &merge_names;
1098
1099        if (head_commit)
1100                remotes = &commit_list_insert(head_commit, remotes)->next;
1101
1102        if (argc == 1 && !strcmp(argv[0], "FETCH_HEAD")) {
1103                handle_fetch_head(remotes, autogen);
1104                remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
1105        } else {
1106                for (i = 0; i < argc; i++) {
1107                        struct commit *commit = get_merge_parent(argv[i]);
1108                        if (!commit)
1109                                help_unknown_ref(argv[i], "merge",
1110                                                 _("not something we can merge"));
1111                        remotes = &commit_list_insert(commit, remotes)->next;
1112                }
1113                remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
1114                if (autogen) {
1115                        struct commit_list *p;
1116                        for (p = remoteheads; p; p = p->next)
1117                                merge_name(merge_remote_util(p->item)->name, autogen);
1118                }
1119        }
1120
1121        if (autogen) {
1122                prepare_merge_message(autogen, merge_msg);
1123                strbuf_release(autogen);
1124        }
1125
1126        return remoteheads;
1127}
1128
1129static int merging_a_throwaway_tag(struct commit *commit)
1130{
1131        char *tag_ref;
1132        struct object_id oid;
1133        int is_throwaway_tag = 0;
1134
1135        /* Are we merging a tag? */
1136        if (!merge_remote_util(commit) ||
1137            !merge_remote_util(commit)->obj ||
1138            merge_remote_util(commit)->obj->type != OBJ_TAG)
1139                return is_throwaway_tag;
1140
1141        /*
1142         * Now we know we are merging a tag object.  Are we downstream
1143         * and following the tags from upstream?  If so, we must have
1144         * the tag object pointed at by "refs/tags/$T" where $T is the
1145         * tagname recorded in the tag object.  We want to allow such
1146         * a "just to catch up" merge to fast-forward.
1147         *
1148         * Otherwise, we are playing an integrator's role, making a
1149         * merge with a throw-away tag from a contributor with
1150         * something like "git pull $contributor $signed_tag".
1151         * We want to forbid such a merge from fast-forwarding
1152         * by default; otherwise we would not keep the signature
1153         * anywhere.
1154         */
1155        tag_ref = xstrfmt("refs/tags/%s",
1156                          ((struct tag *)merge_remote_util(commit)->obj)->tag);
1157        if (!read_ref(tag_ref, &oid) &&
1158            !oidcmp(&oid, &merge_remote_util(commit)->obj->oid))
1159                is_throwaway_tag = 0;
1160        else
1161                is_throwaway_tag = 1;
1162        free(tag_ref);
1163        return is_throwaway_tag;
1164}
1165
1166int cmd_merge(int argc, const char **argv, const char *prefix)
1167{
1168        struct object_id result_tree, stash, head_oid;
1169        struct commit *head_commit;
1170        struct strbuf buf = STRBUF_INIT;
1171        int i, ret = 0, head_subsumed;
1172        int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
1173        struct commit_list *common = NULL;
1174        const char *best_strategy = NULL, *wt_strategy = NULL;
1175        struct commit_list *remoteheads, *p;
1176        void *branch_to_free;
1177        int orig_argc = argc;
1178
1179        if (argc == 2 && !strcmp(argv[1], "-h"))
1180                usage_with_options(builtin_merge_usage, builtin_merge_options);
1181
1182        /*
1183         * Check if we are _not_ on a detached HEAD, i.e. if there is a
1184         * current branch.
1185         */
1186        branch = branch_to_free = resolve_refdup("HEAD", 0, &head_oid, NULL);
1187        if (branch)
1188                skip_prefix(branch, "refs/heads/", &branch);
1189
1190        init_diff_ui_defaults();
1191        git_config(git_merge_config, NULL);
1192
1193        if (!branch || is_null_oid(&head_oid))
1194                head_commit = NULL;
1195        else
1196                head_commit = lookup_commit_or_die(&head_oid, "HEAD");
1197
1198        if (branch_mergeoptions)
1199                parse_branch_merge_options(branch_mergeoptions);
1200        argc = parse_options(argc, argv, prefix, builtin_merge_options,
1201                        builtin_merge_usage, 0);
1202        if (shortlog_len < 0)
1203                shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;
1204
1205        if (verbosity < 0 && show_progress == -1)
1206                show_progress = 0;
1207
1208        if (abort_current_merge) {
1209                int nargc = 2;
1210                const char *nargv[] = {"reset", "--merge", NULL};
1211
1212                if (orig_argc != 2)
1213                        usage_msg_opt(_("--abort expects no arguments"),
1214                              builtin_merge_usage, builtin_merge_options);
1215
1216                if (!file_exists(git_path_merge_head()))
1217                        die(_("There is no merge to abort (MERGE_HEAD missing)."));
1218
1219                /* Invoke 'git reset --merge' */
1220                ret = cmd_reset(nargc, nargv, prefix);
1221                goto done;
1222        }
1223
1224        if (continue_current_merge) {
1225                int nargc = 1;
1226                const char *nargv[] = {"commit", NULL};
1227
1228                if (orig_argc != 2)
1229                        usage_msg_opt(_("--continue expects no arguments"),
1230                              builtin_merge_usage, builtin_merge_options);
1231
1232                if (!file_exists(git_path_merge_head()))
1233                        die(_("There is no merge in progress (MERGE_HEAD missing)."));
1234
1235                /* Invoke 'git commit' */
1236                ret = cmd_commit(nargc, nargv, prefix);
1237                goto done;
1238        }
1239
1240        if (read_cache_unmerged())
1241                die_resolve_conflict("merge");
1242
1243        if (file_exists(git_path_merge_head())) {
1244                /*
1245                 * There is no unmerged entry, don't advise 'git
1246                 * add/rm <file>', just 'git commit'.
1247                 */
1248                if (advice_resolve_conflict)
1249                        die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1250                                  "Please, commit your changes before you merge."));
1251                else
1252                        die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1253        }
1254        if (file_exists(git_path_cherry_pick_head())) {
1255                if (advice_resolve_conflict)
1256                        die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1257                            "Please, commit your changes before you merge."));
1258                else
1259                        die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
1260        }
1261        resolve_undo_clear();
1262
1263        if (verbosity < 0)
1264                show_diffstat = 0;
1265
1266        if (squash) {
1267                if (fast_forward == FF_NO)
1268                        die(_("You cannot combine --squash with --no-ff."));
1269                option_commit = 0;
1270        }
1271
1272        if (!argc) {
1273                if (default_to_upstream)
1274                        argc = setup_with_upstream(&argv);
1275                else
1276                        die(_("No commit specified and merge.defaultToUpstream not set."));
1277        } else if (argc == 1 && !strcmp(argv[0], "-")) {
1278                argv[0] = "@{-1}";
1279        }
1280
1281        if (!argc)
1282                usage_with_options(builtin_merge_usage,
1283                        builtin_merge_options);
1284
1285        if (!head_commit) {
1286                /*
1287                 * If the merged head is a valid one there is no reason
1288                 * to forbid "git merge" into a branch yet to be born.
1289                 * We do the same for "git pull".
1290                 */
1291                struct object_id *remote_head_oid;
1292                if (squash)
1293                        die(_("Squash commit into empty head not supported yet"));
1294                if (fast_forward == FF_NO)
1295                        die(_("Non-fast-forward commit does not make sense into "
1296                            "an empty head"));
1297                remoteheads = collect_parents(head_commit, &head_subsumed,
1298                                              argc, argv, NULL);
1299                if (!remoteheads)
1300                        die(_("%s - not something we can merge"), argv[0]);
1301                if (remoteheads->next)
1302                        die(_("Can merge only exactly one commit into empty head"));
1303                remote_head_oid = &remoteheads->item->object.oid;
1304                read_empty(remote_head_oid, 0);
1305                update_ref("initial pull", "HEAD", remote_head_oid, NULL, 0,
1306                           UPDATE_REFS_DIE_ON_ERR);
1307                goto done;
1308        }
1309
1310        /*
1311         * All the rest are the commits being merged; prepare
1312         * the standard merge summary message to be appended
1313         * to the given message.
1314         */
1315        remoteheads = collect_parents(head_commit, &head_subsumed,
1316                                      argc, argv, &merge_msg);
1317
1318        if (!head_commit || !argc)
1319                usage_with_options(builtin_merge_usage,
1320                        builtin_merge_options);
1321
1322        if (verify_signatures) {
1323                for (p = remoteheads; p; p = p->next) {
1324                        struct commit *commit = p->item;
1325                        char hex[GIT_MAX_HEXSZ + 1];
1326                        struct signature_check signature_check;
1327                        memset(&signature_check, 0, sizeof(signature_check));
1328
1329                        check_commit_signature(commit, &signature_check);
1330
1331                        find_unique_abbrev_r(hex, &commit->object.oid, DEFAULT_ABBREV);
1332                        switch (signature_check.result) {
1333                        case 'G':
1334                                break;
1335                        case 'U':
1336                                die(_("Commit %s has an untrusted GPG signature, "
1337                                      "allegedly by %s."), hex, signature_check.signer);
1338                        case 'B':
1339                                die(_("Commit %s has a bad GPG signature "
1340                                      "allegedly by %s."), hex, signature_check.signer);
1341                        default: /* 'N' */
1342                                die(_("Commit %s does not have a GPG signature."), hex);
1343                        }
1344                        if (verbosity >= 0 && signature_check.result == 'G')
1345                                printf(_("Commit %s has a good GPG signature by %s\n"),
1346                                       hex, signature_check.signer);
1347
1348                        signature_check_clear(&signature_check);
1349                }
1350        }
1351
1352        strbuf_addstr(&buf, "merge");
1353        for (p = remoteheads; p; p = p->next)
1354                strbuf_addf(&buf, " %s", merge_remote_util(p->item)->name);
1355        setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1356        strbuf_reset(&buf);
1357
1358        for (p = remoteheads; p; p = p->next) {
1359                struct commit *commit = p->item;
1360                strbuf_addf(&buf, "GITHEAD_%s",
1361                            oid_to_hex(&commit->object.oid));
1362                setenv(buf.buf, merge_remote_util(commit)->name, 1);
1363                strbuf_reset(&buf);
1364                if (fast_forward != FF_ONLY && merging_a_throwaway_tag(commit))
1365                        fast_forward = FF_NO;
1366        }
1367
1368        if (option_edit < 0)
1369                option_edit = default_edit_option();
1370
1371        if (!use_strategies) {
1372                if (!remoteheads)
1373                        ; /* already up-to-date */
1374                else if (!remoteheads->next)
1375                        add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1376                else
1377                        add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1378        }
1379
1380        for (i = 0; i < use_strategies_nr; i++) {
1381                if (use_strategies[i]->attr & NO_FAST_FORWARD)
1382                        fast_forward = FF_NO;
1383                if (use_strategies[i]->attr & NO_TRIVIAL)
1384                        allow_trivial = 0;
1385        }
1386
1387        if (!remoteheads)
1388                ; /* already up-to-date */
1389        else if (!remoteheads->next)
1390                common = get_merge_bases(head_commit, remoteheads->item);
1391        else {
1392                struct commit_list *list = remoteheads;
1393                commit_list_insert(head_commit, &list);
1394                common = get_octopus_merge_bases(list);
1395                free(list);
1396        }
1397
1398        update_ref("updating ORIG_HEAD", "ORIG_HEAD",
1399                   &head_commit->object.oid, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
1400
1401        if (remoteheads && !common) {
1402                /* No common ancestors found. */
1403                if (!allow_unrelated_histories)
1404                        die(_("refusing to merge unrelated histories"));
1405                /* otherwise, we need a real merge. */
1406        } else if (!remoteheads ||
1407                 (!remoteheads->next && !common->next &&
1408                  common->item == remoteheads->item)) {
1409                /*
1410                 * If head can reach all the merge then we are up to date.
1411                 * but first the most common case of merging one remote.
1412                 */
1413                finish_up_to_date(_("Already up to date."));
1414                goto done;
1415        } else if (fast_forward != FF_NO && !remoteheads->next &&
1416                        !common->next &&
1417                        !oidcmp(&common->item->object.oid, &head_commit->object.oid)) {
1418                /* Again the most common case of merging one remote. */
1419                struct strbuf msg = STRBUF_INIT;
1420                struct commit *commit;
1421
1422                if (verbosity >= 0) {
1423                        printf(_("Updating %s..%s\n"),
1424                               find_unique_abbrev(&head_commit->object.oid,
1425                                                  DEFAULT_ABBREV),
1426                               find_unique_abbrev(&remoteheads->item->object.oid,
1427                                                  DEFAULT_ABBREV));
1428                }
1429                strbuf_addstr(&msg, "Fast-forward");
1430                if (have_message)
1431                        strbuf_addstr(&msg,
1432                                " (no commit created; -m option ignored)");
1433                commit = remoteheads->item;
1434                if (!commit) {
1435                        ret = 1;
1436                        goto done;
1437                }
1438
1439                if (checkout_fast_forward(&head_commit->object.oid,
1440                                          &commit->object.oid,
1441                                          overwrite_ignore)) {
1442                        ret = 1;
1443                        goto done;
1444                }
1445
1446                finish(head_commit, remoteheads, &commit->object.oid, msg.buf);
1447                drop_save();
1448                goto done;
1449        } else if (!remoteheads->next && common->next)
1450                ;
1451                /*
1452                 * We are not doing octopus and not fast-forward.  Need
1453                 * a real merge.
1454                 */
1455        else if (!remoteheads->next && !common->next && option_commit) {
1456                /*
1457                 * We are not doing octopus, not fast-forward, and have
1458                 * only one common.
1459                 */
1460                refresh_cache(REFRESH_QUIET);
1461                if (allow_trivial && fast_forward != FF_ONLY) {
1462                        /* See if it is really trivial. */
1463                        git_committer_info(IDENT_STRICT);
1464                        printf(_("Trying really trivial in-index merge...\n"));
1465                        if (!read_tree_trivial(&common->item->object.oid,
1466                                               &head_commit->object.oid,
1467                                               &remoteheads->item->object.oid)) {
1468                                ret = merge_trivial(head_commit, remoteheads);
1469                                goto done;
1470                        }
1471                        printf(_("Nope.\n"));
1472                }
1473        } else {
1474                /*
1475                 * An octopus.  If we can reach all the remote we are up
1476                 * to date.
1477                 */
1478                int up_to_date = 1;
1479                struct commit_list *j;
1480
1481                for (j = remoteheads; j; j = j->next) {
1482                        struct commit_list *common_one;
1483
1484                        /*
1485                         * Here we *have* to calculate the individual
1486                         * merge_bases again, otherwise "git merge HEAD^
1487                         * HEAD^^" would be missed.
1488                         */
1489                        common_one = get_merge_bases(head_commit, j->item);
1490                        if (oidcmp(&common_one->item->object.oid, &j->item->object.oid)) {
1491                                up_to_date = 0;
1492                                break;
1493                        }
1494                }
1495                if (up_to_date) {
1496                        finish_up_to_date(_("Already up to date. Yeeah!"));
1497                        goto done;
1498                }
1499        }
1500
1501        if (fast_forward == FF_ONLY)
1502                die(_("Not possible to fast-forward, aborting."));
1503
1504        /* We are going to make a new commit. */
1505        git_committer_info(IDENT_STRICT);
1506
1507        /*
1508         * At this point, we need a real merge.  No matter what strategy
1509         * we use, it would operate on the index, possibly affecting the
1510         * working tree, and when resolved cleanly, have the desired
1511         * tree in the index -- this means that the index must be in
1512         * sync with the head commit.  The strategies are responsible
1513         * to ensure this.
1514         */
1515        if (use_strategies_nr == 1 ||
1516            /*
1517             * Stash away the local changes so that we can try more than one.
1518             */
1519            save_state(&stash))
1520                oidclr(&stash);
1521
1522        for (i = 0; i < use_strategies_nr; i++) {
1523                int ret;
1524                if (i) {
1525                        printf(_("Rewinding the tree to pristine...\n"));
1526                        restore_state(&head_commit->object.oid, &stash);
1527                }
1528                if (use_strategies_nr != 1)
1529                        printf(_("Trying merge strategy %s...\n"),
1530                                use_strategies[i]->name);
1531                /*
1532                 * Remember which strategy left the state in the working
1533                 * tree.
1534                 */
1535                wt_strategy = use_strategies[i]->name;
1536
1537                ret = try_merge_strategy(use_strategies[i]->name,
1538                                         common, remoteheads,
1539                                         head_commit);
1540                if (!option_commit && !ret) {
1541                        merge_was_ok = 1;
1542                        /*
1543                         * This is necessary here just to avoid writing
1544                         * the tree, but later we will *not* exit with
1545                         * status code 1 because merge_was_ok is set.
1546                         */
1547                        ret = 1;
1548                }
1549
1550                if (ret) {
1551                        /*
1552                         * The backend exits with 1 when conflicts are
1553                         * left to be resolved, with 2 when it does not
1554                         * handle the given merge at all.
1555                         */
1556                        if (ret == 1) {
1557                                int cnt = evaluate_result();
1558
1559                                if (best_cnt <= 0 || cnt <= best_cnt) {
1560                                        best_strategy = use_strategies[i]->name;
1561                                        best_cnt = cnt;
1562                                }
1563                        }
1564                        if (merge_was_ok)
1565                                break;
1566                        else
1567                                continue;
1568                }
1569
1570                /* Automerge succeeded. */
1571                write_tree_trivial(&result_tree);
1572                automerge_was_ok = 1;
1573                break;
1574        }
1575
1576        /*
1577         * If we have a resulting tree, that means the strategy module
1578         * auto resolved the merge cleanly.
1579         */
1580        if (automerge_was_ok) {
1581                ret = finish_automerge(head_commit, head_subsumed,
1582                                       common, remoteheads,
1583                                       &result_tree, wt_strategy);
1584                goto done;
1585        }
1586
1587        /*
1588         * Pick the result from the best strategy and have the user fix
1589         * it up.
1590         */
1591        if (!best_strategy) {
1592                restore_state(&head_commit->object.oid, &stash);
1593                if (use_strategies_nr > 1)
1594                        fprintf(stderr,
1595                                _("No merge strategy handled the merge.\n"));
1596                else
1597                        fprintf(stderr, _("Merge with strategy %s failed.\n"),
1598                                use_strategies[0]->name);
1599                ret = 2;
1600                goto done;
1601        } else if (best_strategy == wt_strategy)
1602                ; /* We already have its result in the working tree. */
1603        else {
1604                printf(_("Rewinding the tree to pristine...\n"));
1605                restore_state(&head_commit->object.oid, &stash);
1606                printf(_("Using the %s to prepare resolving by hand.\n"),
1607                        best_strategy);
1608                try_merge_strategy(best_strategy, common, remoteheads,
1609                                   head_commit);
1610        }
1611
1612        if (squash)
1613                finish(head_commit, remoteheads, NULL, NULL);
1614        else
1615                write_merge_state(remoteheads);
1616
1617        if (merge_was_ok)
1618                fprintf(stderr, _("Automatic merge went well; "
1619                        "stopped before committing as requested\n"));
1620        else
1621                ret = suggest_conflicts();
1622
1623done:
1624        free(branch_to_free);
1625        return ret;
1626}