builtin / merge.con commit Merge branch 'cb/remove-dead-init' (48542e3)
   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#include "commit-reach.h"
  40
  41#define DEFAULT_TWOHEAD (1<<0)
  42#define DEFAULT_OCTOPUS (1<<1)
  43#define NO_FAST_FORWARD (1<<2)
  44#define NO_TRIVIAL      (1<<3)
  45
  46struct strategy {
  47        const char *name;
  48        unsigned attr;
  49};
  50
  51static const char * const builtin_merge_usage[] = {
  52        N_("git merge [<options>] [<commit>...]"),
  53        N_("git merge --abort"),
  54        N_("git merge --continue"),
  55        NULL
  56};
  57
  58static int show_diffstat = 1, shortlog_len = -1, squash;
  59static int option_commit = 1;
  60static int option_edit = -1;
  61static int allow_trivial = 1, have_message, verify_signatures;
  62static int overwrite_ignore = 1;
  63static struct strbuf merge_msg = STRBUF_INIT;
  64static struct strategy **use_strategies;
  65static size_t use_strategies_nr, use_strategies_alloc;
  66static const char **xopts;
  67static size_t xopts_nr, xopts_alloc;
  68static const char *branch;
  69static char *branch_mergeoptions;
  70static int option_renormalize;
  71static int verbosity;
  72static int allow_rerere_auto;
  73static int abort_current_merge;
  74static int continue_current_merge;
  75static int allow_unrelated_histories;
  76static int show_progress = -1;
  77static int default_to_upstream = 1;
  78static int signoff;
  79static const char *sign_commit;
  80static int verify_msg = 1;
  81
  82static struct strategy all_strategy[] = {
  83        { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
  84        { "octopus",    DEFAULT_OCTOPUS },
  85        { "resolve",    0 },
  86        { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
  87        { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
  88};
  89
  90static const char *pull_twohead, *pull_octopus;
  91
  92enum ff_type {
  93        FF_NO,
  94        FF_ALLOW,
  95        FF_ONLY
  96};
  97
  98static enum ff_type fast_forward = FF_ALLOW;
  99
 100static int option_parse_message(const struct option *opt,
 101                                const char *arg, int unset)
 102{
 103        struct strbuf *buf = opt->value;
 104
 105        if (unset)
 106                strbuf_setlen(buf, 0);
 107        else if (arg) {
 108                strbuf_addf(buf, "%s%s", buf->len ? "\n\n" : "", arg);
 109                have_message = 1;
 110        } else
 111                return error(_("switch `m' requires a value"));
 112        return 0;
 113}
 114
 115static int option_read_message(struct parse_opt_ctx_t *ctx,
 116                               const struct option *opt, int unset)
 117{
 118        struct strbuf *buf = opt->value;
 119        const char *arg;
 120
 121        if (unset)
 122                BUG("-F cannot be negated");
 123
 124        if (ctx->opt) {
 125                arg = ctx->opt;
 126                ctx->opt = NULL;
 127        } else if (ctx->argc > 1) {
 128                ctx->argc--;
 129                arg = *++ctx->argv;
 130        } else
 131                return opterror(opt, "requires a value", 0);
 132
 133        if (buf->len)
 134                strbuf_addch(buf, '\n');
 135        if (ctx->prefix && !is_absolute_path(arg))
 136                arg = prefix_filename(ctx->prefix, arg);
 137        if (strbuf_read_file(buf, arg, 0) < 0)
 138                return error(_("could not read file '%s'"), arg);
 139        have_message = 1;
 140
 141        return 0;
 142}
 143
 144static struct strategy *get_strategy(const char *name)
 145{
 146        int i;
 147        struct strategy *ret;
 148        static struct cmdnames main_cmds, other_cmds;
 149        static int loaded;
 150
 151        if (!name)
 152                return NULL;
 153
 154        for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 155                if (!strcmp(name, all_strategy[i].name))
 156                        return &all_strategy[i];
 157
 158        if (!loaded) {
 159                struct cmdnames not_strategies;
 160                loaded = 1;
 161
 162                memset(&not_strategies, 0, sizeof(struct cmdnames));
 163                load_command_list("git-merge-", &main_cmds, &other_cmds);
 164                for (i = 0; i < main_cmds.cnt; i++) {
 165                        int j, found = 0;
 166                        struct cmdname *ent = main_cmds.names[i];
 167                        for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
 168                                if (!strncmp(ent->name, all_strategy[j].name, ent->len)
 169                                                && !all_strategy[j].name[ent->len])
 170                                        found = 1;
 171                        if (!found)
 172                                add_cmdname(&not_strategies, ent->name, ent->len);
 173                }
 174                exclude_cmds(&main_cmds, &not_strategies);
 175        }
 176        if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
 177                fprintf(stderr, _("Could not find merge strategy '%s'.\n"), name);
 178                fprintf(stderr, _("Available strategies are:"));
 179                for (i = 0; i < main_cmds.cnt; i++)
 180                        fprintf(stderr, " %s", main_cmds.names[i]->name);
 181                fprintf(stderr, ".\n");
 182                if (other_cmds.cnt) {
 183                        fprintf(stderr, _("Available custom strategies are:"));
 184                        for (i = 0; i < other_cmds.cnt; i++)
 185                                fprintf(stderr, " %s", other_cmds.names[i]->name);
 186                        fprintf(stderr, ".\n");
 187                }
 188                exit(1);
 189        }
 190
 191        ret = xcalloc(1, sizeof(struct strategy));
 192        ret->name = xstrdup(name);
 193        ret->attr = NO_TRIVIAL;
 194        return ret;
 195}
 196
 197static void append_strategy(struct strategy *s)
 198{
 199        ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
 200        use_strategies[use_strategies_nr++] = s;
 201}
 202
 203static int option_parse_strategy(const struct option *opt,
 204                                 const char *name, int unset)
 205{
 206        if (unset)
 207                return 0;
 208
 209        append_strategy(get_strategy(name));
 210        return 0;
 211}
 212
 213static int option_parse_x(const struct option *opt,
 214                          const char *arg, int unset)
 215{
 216        if (unset)
 217                return 0;
 218
 219        ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
 220        xopts[xopts_nr++] = xstrdup(arg);
 221        return 0;
 222}
 223
 224static int option_parse_n(const struct option *opt,
 225                          const char *arg, int unset)
 226{
 227        show_diffstat = unset;
 228        return 0;
 229}
 230
 231static struct option builtin_merge_options[] = {
 232        { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
 233                N_("do not show a diffstat at the end of the merge"),
 234                PARSE_OPT_NOARG, option_parse_n },
 235        OPT_BOOL(0, "stat", &show_diffstat,
 236                N_("show a diffstat at the end of the merge")),
 237        OPT_BOOL(0, "summary", &show_diffstat, N_("(synonym to --stat)")),
 238        { OPTION_INTEGER, 0, "log", &shortlog_len, N_("n"),
 239          N_("add (at most <n>) entries from shortlog to merge commit message"),
 240          PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
 241        OPT_BOOL(0, "squash", &squash,
 242                N_("create a single commit instead of doing a merge")),
 243        OPT_BOOL(0, "commit", &option_commit,
 244                N_("perform a commit if the merge succeeds (default)")),
 245        OPT_BOOL('e', "edit", &option_edit,
 246                N_("edit message before committing")),
 247        OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
 248        OPT_SET_INT_F(0, "ff-only", &fast_forward,
 249                      N_("abort if fast-forward is not possible"),
 250                      FF_ONLY, PARSE_OPT_NONEG),
 251        OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
 252        OPT_BOOL(0, "verify-signatures", &verify_signatures,
 253                N_("verify that the named commit has a valid GPG signature")),
 254        OPT_CALLBACK('s', "strategy", &use_strategies, N_("strategy"),
 255                N_("merge strategy to use"), option_parse_strategy),
 256        OPT_CALLBACK('X', "strategy-option", &xopts, N_("option=value"),
 257                N_("option for selected merge strategy"), option_parse_x),
 258        OPT_CALLBACK('m', "message", &merge_msg, N_("message"),
 259                N_("merge commit message (for a non-fast-forward merge)"),
 260                option_parse_message),
 261        { OPTION_LOWLEVEL_CALLBACK, 'F', "file", &merge_msg, N_("path"),
 262                N_("read message from file"), PARSE_OPT_NONEG,
 263                (parse_opt_cb *) option_read_message },
 264        OPT__VERBOSITY(&verbosity),
 265        OPT_BOOL(0, "abort", &abort_current_merge,
 266                N_("abort the current in-progress merge")),
 267        OPT_BOOL(0, "continue", &continue_current_merge,
 268                N_("continue the current in-progress merge")),
 269        OPT_BOOL(0, "allow-unrelated-histories", &allow_unrelated_histories,
 270                 N_("allow merging unrelated histories")),
 271        OPT_SET_INT(0, "progress", &show_progress, N_("force progress reporting"), 1),
 272        { OPTION_STRING, 'S', "gpg-sign", &sign_commit, N_("key-id"),
 273          N_("GPG sign commit"), PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
 274        OPT_BOOL(0, "overwrite-ignore", &overwrite_ignore, N_("update ignored files (default)")),
 275        OPT_BOOL(0, "signoff", &signoff, N_("add Signed-off-by:")),
 276        OPT_BOOL(0, "verify", &verify_msg, N_("verify commit-msg hook")),
 277        OPT_END()
 278};
 279
 280/* Cleans up metadata that is uninteresting after a succeeded merge. */
 281static void drop_save(void)
 282{
 283        unlink(git_path_merge_head(the_repository));
 284        unlink(git_path_merge_msg(the_repository));
 285        unlink(git_path_merge_mode(the_repository));
 286}
 287
 288static int save_state(struct object_id *stash)
 289{
 290        int len;
 291        struct child_process cp = CHILD_PROCESS_INIT;
 292        struct strbuf buffer = STRBUF_INIT;
 293        const char *argv[] = {"stash", "create", NULL};
 294        int rc = -1;
 295
 296        cp.argv = argv;
 297        cp.out = -1;
 298        cp.git_cmd = 1;
 299
 300        if (start_command(&cp))
 301                die(_("could not run stash."));
 302        len = strbuf_read(&buffer, cp.out, 1024);
 303        close(cp.out);
 304
 305        if (finish_command(&cp) || len < 0)
 306                die(_("stash failed"));
 307        else if (!len)          /* no changes */
 308                goto out;
 309        strbuf_setlen(&buffer, buffer.len-1);
 310        if (get_oid(buffer.buf, stash))
 311                die(_("not a valid object: %s"), buffer.buf);
 312        rc = 0;
 313out:
 314        strbuf_release(&buffer);
 315        return rc;
 316}
 317
 318static void read_empty(const struct object_id *oid, int verbose)
 319{
 320        int i = 0;
 321        const char *args[7];
 322
 323        args[i++] = "read-tree";
 324        if (verbose)
 325                args[i++] = "-v";
 326        args[i++] = "-m";
 327        args[i++] = "-u";
 328        args[i++] = empty_tree_oid_hex();
 329        args[i++] = oid_to_hex(oid);
 330        args[i] = NULL;
 331
 332        if (run_command_v_opt(args, RUN_GIT_CMD))
 333                die(_("read-tree failed"));
 334}
 335
 336static void reset_hard(const struct object_id *oid, int verbose)
 337{
 338        int i = 0;
 339        const char *args[6];
 340
 341        args[i++] = "read-tree";
 342        if (verbose)
 343                args[i++] = "-v";
 344        args[i++] = "--reset";
 345        args[i++] = "-u";
 346        args[i++] = oid_to_hex(oid);
 347        args[i] = NULL;
 348
 349        if (run_command_v_opt(args, RUN_GIT_CMD))
 350                die(_("read-tree failed"));
 351}
 352
 353static void restore_state(const struct object_id *head,
 354                          const struct object_id *stash)
 355{
 356        struct strbuf sb = STRBUF_INIT;
 357        const char *args[] = { "stash", "apply", NULL, NULL };
 358
 359        if (is_null_oid(stash))
 360                return;
 361
 362        reset_hard(head, 1);
 363
 364        args[2] = oid_to_hex(stash);
 365
 366        /*
 367         * It is OK to ignore error here, for example when there was
 368         * nothing to restore.
 369         */
 370        run_command_v_opt(args, RUN_GIT_CMD);
 371
 372        strbuf_release(&sb);
 373        refresh_cache(REFRESH_QUIET);
 374}
 375
 376/* This is called when no merge was necessary. */
 377static void finish_up_to_date(const char *msg)
 378{
 379        if (verbosity >= 0)
 380                printf("%s%s\n", squash ? _(" (nothing to squash)") : "", msg);
 381        drop_save();
 382}
 383
 384static void squash_message(struct commit *commit, struct commit_list *remoteheads)
 385{
 386        struct rev_info rev;
 387        struct strbuf out = STRBUF_INIT;
 388        struct commit_list *j;
 389        struct pretty_print_context ctx = {0};
 390
 391        printf(_("Squash commit -- not updating HEAD\n"));
 392
 393        repo_init_revisions(the_repository, &rev, NULL);
 394        rev.ignore_merges = 1;
 395        rev.commit_format = CMIT_FMT_MEDIUM;
 396
 397        commit->object.flags |= UNINTERESTING;
 398        add_pending_object(&rev, &commit->object, NULL);
 399
 400        for (j = remoteheads; j; j = j->next)
 401                add_pending_object(&rev, &j->item->object, NULL);
 402
 403        setup_revisions(0, NULL, &rev, NULL);
 404        if (prepare_revision_walk(&rev))
 405                die(_("revision walk setup failed"));
 406
 407        ctx.abbrev = rev.abbrev;
 408        ctx.date_mode = rev.date_mode;
 409        ctx.fmt = rev.commit_format;
 410
 411        strbuf_addstr(&out, "Squashed commit of the following:\n");
 412        while ((commit = get_revision(&rev)) != NULL) {
 413                strbuf_addch(&out, '\n');
 414                strbuf_addf(&out, "commit %s\n",
 415                        oid_to_hex(&commit->object.oid));
 416                pretty_print_commit(&ctx, commit, &out);
 417        }
 418        write_file_buf(git_path_squash_msg(the_repository), out.buf, out.len);
 419        strbuf_release(&out);
 420}
 421
 422static void finish(struct commit *head_commit,
 423                   struct commit_list *remoteheads,
 424                   const struct object_id *new_head, const char *msg)
 425{
 426        struct strbuf reflog_message = STRBUF_INIT;
 427        const struct object_id *head = &head_commit->object.oid;
 428
 429        if (!msg)
 430                strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
 431        else {
 432                if (verbosity >= 0)
 433                        printf("%s\n", msg);
 434                strbuf_addf(&reflog_message, "%s: %s",
 435                        getenv("GIT_REFLOG_ACTION"), msg);
 436        }
 437        if (squash) {
 438                squash_message(head_commit, remoteheads);
 439        } else {
 440                if (verbosity >= 0 && !merge_msg.len)
 441                        printf(_("No merge message -- not updating HEAD\n"));
 442                else {
 443                        const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 444                        update_ref(reflog_message.buf, "HEAD", new_head, head,
 445                                   0, UPDATE_REFS_DIE_ON_ERR);
 446                        /*
 447                         * We ignore errors in 'gc --auto', since the
 448                         * user should see them.
 449                         */
 450                        close_all_packs(the_repository->objects);
 451                        run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 452                }
 453        }
 454        if (new_head && show_diffstat) {
 455                struct diff_options opts;
 456                repo_diff_setup(the_repository, &opts);
 457                opts.stat_width = -1; /* use full terminal width */
 458                opts.stat_graph_width = -1; /* respect statGraphWidth config */
 459                opts.output_format |=
 460                        DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 461                opts.detect_rename = DIFF_DETECT_RENAME;
 462                diff_setup_done(&opts);
 463                diff_tree_oid(head, new_head, "", &opts);
 464                diffcore_std(&opts);
 465                diff_flush(&opts);
 466        }
 467
 468        /* Run a post-merge hook */
 469        run_hook_le(NULL, "post-merge", squash ? "1" : "0", NULL);
 470
 471        strbuf_release(&reflog_message);
 472}
 473
 474/* Get the name for the merge commit's message. */
 475static void merge_name(const char *remote, struct strbuf *msg)
 476{
 477        struct commit *remote_head;
 478        struct object_id branch_head;
 479        struct strbuf buf = STRBUF_INIT;
 480        struct strbuf bname = STRBUF_INIT;
 481        struct merge_remote_desc *desc;
 482        const char *ptr;
 483        char *found_ref;
 484        int len, early;
 485
 486        strbuf_branchname(&bname, remote, 0);
 487        remote = bname.buf;
 488
 489        oidclr(&branch_head);
 490        remote_head = get_merge_parent(remote);
 491        if (!remote_head)
 492                die(_("'%s' does not point to a commit"), remote);
 493
 494        if (dwim_ref(remote, strlen(remote), &branch_head, &found_ref) > 0) {
 495                if (starts_with(found_ref, "refs/heads/")) {
 496                        strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 497                                    oid_to_hex(&branch_head), remote);
 498                        goto cleanup;
 499                }
 500                if (starts_with(found_ref, "refs/tags/")) {
 501                        strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
 502                                    oid_to_hex(&branch_head), remote);
 503                        goto cleanup;
 504                }
 505                if (starts_with(found_ref, "refs/remotes/")) {
 506                        strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
 507                                    oid_to_hex(&branch_head), remote);
 508                        goto cleanup;
 509                }
 510        }
 511
 512        /* See if remote matches <name>^^^.. or <name>~<number> */
 513        for (len = 0, ptr = remote + strlen(remote);
 514             remote < ptr && ptr[-1] == '^';
 515             ptr--)
 516                len++;
 517        if (len)
 518                early = 1;
 519        else {
 520                early = 0;
 521                ptr = strrchr(remote, '~');
 522                if (ptr) {
 523                        int seen_nonzero = 0;
 524
 525                        len++; /* count ~ */
 526                        while (*++ptr && isdigit(*ptr)) {
 527                                seen_nonzero |= (*ptr != '0');
 528                                len++;
 529                        }
 530                        if (*ptr)
 531                                len = 0; /* not ...~<number> */
 532                        else if (seen_nonzero)
 533                                early = 1;
 534                        else if (len == 1)
 535                                early = 1; /* "name~" is "name~1"! */
 536                }
 537        }
 538        if (len) {
 539                struct strbuf truname = STRBUF_INIT;
 540                strbuf_addf(&truname, "refs/heads/%s", remote);
 541                strbuf_setlen(&truname, truname.len - len);
 542                if (ref_exists(truname.buf)) {
 543                        strbuf_addf(msg,
 544                                    "%s\t\tbranch '%s'%s of .\n",
 545                                    oid_to_hex(&remote_head->object.oid),
 546                                    truname.buf + 11,
 547                                    (early ? " (early part)" : ""));
 548                        strbuf_release(&truname);
 549                        goto cleanup;
 550                }
 551                strbuf_release(&truname);
 552        }
 553
 554        desc = merge_remote_util(remote_head);
 555        if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
 556                strbuf_addf(msg, "%s\t\t%s '%s'\n",
 557                            oid_to_hex(&desc->obj->oid),
 558                            type_name(desc->obj->type),
 559                            remote);
 560                goto cleanup;
 561        }
 562
 563        strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 564                oid_to_hex(&remote_head->object.oid), remote);
 565cleanup:
 566        strbuf_release(&buf);
 567        strbuf_release(&bname);
 568}
 569
 570static void parse_branch_merge_options(char *bmo)
 571{
 572        const char **argv;
 573        int argc;
 574
 575        if (!bmo)
 576                return;
 577        argc = split_cmdline(bmo, &argv);
 578        if (argc < 0)
 579                die(_("Bad branch.%s.mergeoptions string: %s"), branch,
 580                    split_cmdline_strerror(argc));
 581        REALLOC_ARRAY(argv, argc + 2);
 582        MOVE_ARRAY(argv + 1, argv, argc + 1);
 583        argc++;
 584        argv[0] = "branch.*.mergeoptions";
 585        parse_options(argc, argv, NULL, builtin_merge_options,
 586                      builtin_merge_usage, 0);
 587        free(argv);
 588}
 589
 590static int git_merge_config(const char *k, const char *v, void *cb)
 591{
 592        int status;
 593
 594        if (branch && starts_with(k, "branch.") &&
 595                starts_with(k + 7, branch) &&
 596                !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
 597                free(branch_mergeoptions);
 598                branch_mergeoptions = xstrdup(v);
 599                return 0;
 600        }
 601
 602        if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 603                show_diffstat = git_config_bool(k, v);
 604        else if (!strcmp(k, "merge.verifysignatures"))
 605                verify_signatures = git_config_bool(k, v);
 606        else if (!strcmp(k, "pull.twohead"))
 607                return git_config_string(&pull_twohead, k, v);
 608        else if (!strcmp(k, "pull.octopus"))
 609                return git_config_string(&pull_octopus, k, v);
 610        else if (!strcmp(k, "merge.renormalize"))
 611                option_renormalize = git_config_bool(k, v);
 612        else if (!strcmp(k, "merge.ff")) {
 613                int boolval = git_parse_maybe_bool(v);
 614                if (0 <= boolval) {
 615                        fast_forward = boolval ? FF_ALLOW : FF_NO;
 616                } else if (v && !strcmp(v, "only")) {
 617                        fast_forward = FF_ONLY;
 618                } /* do not barf on values from future versions of git */
 619                return 0;
 620        } else if (!strcmp(k, "merge.defaulttoupstream")) {
 621                default_to_upstream = git_config_bool(k, v);
 622                return 0;
 623        } else if (!strcmp(k, "commit.gpgsign")) {
 624                sign_commit = git_config_bool(k, v) ? "" : NULL;
 625                return 0;
 626        }
 627
 628        status = fmt_merge_msg_config(k, v, cb);
 629        if (status)
 630                return status;
 631        status = git_gpg_config(k, v, NULL);
 632        if (status)
 633                return status;
 634        return git_diff_ui_config(k, v, cb);
 635}
 636
 637static int read_tree_trivial(struct object_id *common, struct object_id *head,
 638                             struct object_id *one)
 639{
 640        int i, nr_trees = 0;
 641        struct tree *trees[MAX_UNPACK_TREES];
 642        struct tree_desc t[MAX_UNPACK_TREES];
 643        struct unpack_trees_options opts;
 644
 645        memset(&opts, 0, sizeof(opts));
 646        opts.head_idx = 2;
 647        opts.src_index = &the_index;
 648        opts.dst_index = &the_index;
 649        opts.update = 1;
 650        opts.verbose_update = 1;
 651        opts.trivial_merges_only = 1;
 652        opts.merge = 1;
 653        trees[nr_trees] = parse_tree_indirect(common);
 654        if (!trees[nr_trees++])
 655                return -1;
 656        trees[nr_trees] = parse_tree_indirect(head);
 657        if (!trees[nr_trees++])
 658                return -1;
 659        trees[nr_trees] = parse_tree_indirect(one);
 660        if (!trees[nr_trees++])
 661                return -1;
 662        opts.fn = threeway_merge;
 663        cache_tree_free(&active_cache_tree);
 664        for (i = 0; i < nr_trees; i++) {
 665                parse_tree(trees[i]);
 666                init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 667        }
 668        if (unpack_trees(nr_trees, t, &opts))
 669                return -1;
 670        return 0;
 671}
 672
 673static void write_tree_trivial(struct object_id *oid)
 674{
 675        if (write_cache_as_tree(oid, 0, NULL))
 676                die(_("git write-tree failed to write a tree"));
 677}
 678
 679static int try_merge_strategy(const char *strategy, struct commit_list *common,
 680                              struct commit_list *remoteheads,
 681                              struct commit *head)
 682{
 683        struct lock_file lock = LOCK_INIT;
 684        const char *head_arg = "HEAD";
 685
 686        hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
 687        refresh_cache(REFRESH_QUIET);
 688        if (write_locked_index(&the_index, &lock,
 689                               COMMIT_LOCK | SKIP_IF_UNCHANGED))
 690                return error(_("Unable to write index."));
 691
 692        if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
 693                int clean, x;
 694                struct commit *result;
 695                struct commit_list *reversed = NULL;
 696                struct merge_options o;
 697                struct commit_list *j;
 698
 699                if (remoteheads->next) {
 700                        error(_("Not handling anything other than two heads merge."));
 701                        return 2;
 702                }
 703
 704                init_merge_options(&o);
 705                if (!strcmp(strategy, "subtree"))
 706                        o.subtree_shift = "";
 707
 708                o.renormalize = option_renormalize;
 709                o.show_rename_progress =
 710                        show_progress == -1 ? isatty(2) : show_progress;
 711
 712                for (x = 0; x < xopts_nr; x++)
 713                        if (parse_merge_opt(&o, xopts[x]))
 714                                die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
 715
 716                o.branch1 = head_arg;
 717                o.branch2 = merge_remote_util(remoteheads->item)->name;
 718
 719                for (j = common; j; j = j->next)
 720                        commit_list_insert(j->item, &reversed);
 721
 722                hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
 723                clean = merge_recursive(&o, head,
 724                                remoteheads->item, reversed, &result);
 725                if (clean < 0)
 726                        exit(128);
 727                if (write_locked_index(&the_index, &lock,
 728                                       COMMIT_LOCK | SKIP_IF_UNCHANGED))
 729                        die(_("unable to write %s"), get_index_file());
 730                return clean ? 0 : 1;
 731        } else {
 732                return try_merge_command(the_repository,
 733                                         strategy, xopts_nr, xopts,
 734                                         common, head_arg, remoteheads);
 735        }
 736}
 737
 738static void count_diff_files(struct diff_queue_struct *q,
 739                             struct diff_options *opt, void *data)
 740{
 741        int *count = data;
 742
 743        (*count) += q->nr;
 744}
 745
 746static int count_unmerged_entries(void)
 747{
 748        int i, ret = 0;
 749
 750        for (i = 0; i < active_nr; i++)
 751                if (ce_stage(active_cache[i]))
 752                        ret++;
 753
 754        return ret;
 755}
 756
 757static void add_strategies(const char *string, unsigned attr)
 758{
 759        int i;
 760
 761        if (string) {
 762                struct string_list list = STRING_LIST_INIT_DUP;
 763                struct string_list_item *item;
 764                string_list_split(&list, string, ' ', -1);
 765                for_each_string_list_item(item, &list)
 766                        append_strategy(get_strategy(item->string));
 767                string_list_clear(&list, 0);
 768                return;
 769        }
 770        for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 771                if (all_strategy[i].attr & attr)
 772                        append_strategy(&all_strategy[i]);
 773
 774}
 775
 776static void read_merge_msg(struct strbuf *msg)
 777{
 778        const char *filename = git_path_merge_msg(the_repository);
 779        strbuf_reset(msg);
 780        if (strbuf_read_file(msg, filename, 0) < 0)
 781                die_errno(_("Could not read from '%s'"), filename);
 782}
 783
 784static void write_merge_state(struct commit_list *);
 785static void abort_commit(struct commit_list *remoteheads, const char *err_msg)
 786{
 787        if (err_msg)
 788                error("%s", err_msg);
 789        fprintf(stderr,
 790                _("Not committing merge; use 'git commit' to complete the merge.\n"));
 791        write_merge_state(remoteheads);
 792        exit(1);
 793}
 794
 795static const char merge_editor_comment[] =
 796N_("Please enter a commit message to explain why this merge is necessary,\n"
 797   "especially if it merges an updated upstream into a topic branch.\n"
 798   "\n"
 799   "Lines starting with '%c' will be ignored, and an empty message aborts\n"
 800   "the commit.\n");
 801
 802static void write_merge_heads(struct commit_list *);
 803static void prepare_to_commit(struct commit_list *remoteheads)
 804{
 805        struct strbuf msg = STRBUF_INIT;
 806        strbuf_addbuf(&msg, &merge_msg);
 807        strbuf_addch(&msg, '\n');
 808        if (squash)
 809                BUG("the control must not reach here under --squash");
 810        if (0 < option_edit)
 811                strbuf_commented_addf(&msg, _(merge_editor_comment), comment_line_char);
 812        if (signoff)
 813                append_signoff(&msg, ignore_non_trailer(msg.buf, msg.len), 0);
 814        write_merge_heads(remoteheads);
 815        write_file_buf(git_path_merge_msg(the_repository), msg.buf, msg.len);
 816        if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
 817                            git_path_merge_msg(the_repository), "merge", NULL))
 818                abort_commit(remoteheads, NULL);
 819        if (0 < option_edit) {
 820                if (launch_editor(git_path_merge_msg(the_repository), NULL, NULL))
 821                        abort_commit(remoteheads, NULL);
 822        }
 823
 824        if (verify_msg && run_commit_hook(0 < option_edit, get_index_file(),
 825                                          "commit-msg",
 826                                          git_path_merge_msg(the_repository), NULL))
 827                abort_commit(remoteheads, NULL);
 828
 829        read_merge_msg(&msg);
 830        strbuf_stripspace(&msg, 0 < option_edit);
 831        if (!msg.len)
 832                abort_commit(remoteheads, _("Empty commit message."));
 833        strbuf_release(&merge_msg);
 834        strbuf_addbuf(&merge_msg, &msg);
 835        strbuf_release(&msg);
 836}
 837
 838static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
 839{
 840        struct object_id result_tree, result_commit;
 841        struct commit_list *parents, **pptr = &parents;
 842        struct lock_file lock = LOCK_INIT;
 843
 844        hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
 845        refresh_cache(REFRESH_QUIET);
 846        if (write_locked_index(&the_index, &lock,
 847                               COMMIT_LOCK | SKIP_IF_UNCHANGED))
 848                return error(_("Unable to write index."));
 849
 850        write_tree_trivial(&result_tree);
 851        printf(_("Wonderful.\n"));
 852        pptr = commit_list_append(head, pptr);
 853        pptr = commit_list_append(remoteheads->item, pptr);
 854        prepare_to_commit(remoteheads);
 855        if (commit_tree(merge_msg.buf, merge_msg.len, &result_tree, parents,
 856                        &result_commit, NULL, sign_commit))
 857                die(_("failed to write commit object"));
 858        finish(head, remoteheads, &result_commit, "In-index merge");
 859        drop_save();
 860        return 0;
 861}
 862
 863static int finish_automerge(struct commit *head,
 864                            int head_subsumed,
 865                            struct commit_list *common,
 866                            struct commit_list *remoteheads,
 867                            struct object_id *result_tree,
 868                            const char *wt_strategy)
 869{
 870        struct commit_list *parents = NULL;
 871        struct strbuf buf = STRBUF_INIT;
 872        struct object_id result_commit;
 873
 874        free_commit_list(common);
 875        parents = remoteheads;
 876        if (!head_subsumed || fast_forward == FF_NO)
 877                commit_list_insert(head, &parents);
 878        strbuf_addch(&merge_msg, '\n');
 879        prepare_to_commit(remoteheads);
 880        if (commit_tree(merge_msg.buf, merge_msg.len, result_tree, parents,
 881                        &result_commit, NULL, sign_commit))
 882                die(_("failed to write commit object"));
 883        strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
 884        finish(head, remoteheads, &result_commit, buf.buf);
 885        strbuf_release(&buf);
 886        drop_save();
 887        return 0;
 888}
 889
 890static int suggest_conflicts(void)
 891{
 892        const char *filename;
 893        FILE *fp;
 894        struct strbuf msgbuf = STRBUF_INIT;
 895
 896        filename = git_path_merge_msg(the_repository);
 897        fp = xfopen(filename, "a");
 898
 899        append_conflicts_hint(&msgbuf);
 900        fputs(msgbuf.buf, fp);
 901        strbuf_release(&msgbuf);
 902        fclose(fp);
 903        repo_rerere(the_repository, allow_rerere_auto);
 904        printf(_("Automatic merge failed; "
 905                        "fix conflicts and then commit the result.\n"));
 906        return 1;
 907}
 908
 909static int evaluate_result(void)
 910{
 911        int cnt = 0;
 912        struct rev_info rev;
 913
 914        /* Check how many files differ. */
 915        repo_init_revisions(the_repository, &rev, "");
 916        setup_revisions(0, NULL, &rev, NULL);
 917        rev.diffopt.output_format |=
 918                DIFF_FORMAT_CALLBACK;
 919        rev.diffopt.format_callback = count_diff_files;
 920        rev.diffopt.format_callback_data = &cnt;
 921        run_diff_files(&rev, 0);
 922
 923        /*
 924         * Check how many unmerged entries are
 925         * there.
 926         */
 927        cnt += count_unmerged_entries();
 928
 929        return cnt;
 930}
 931
 932/*
 933 * Pretend as if the user told us to merge with the remote-tracking
 934 * branch we have for the upstream of the current branch
 935 */
 936static int setup_with_upstream(const char ***argv)
 937{
 938        struct branch *branch = branch_get(NULL);
 939        int i;
 940        const char **args;
 941
 942        if (!branch)
 943                die(_("No current branch."));
 944        if (!branch->remote_name)
 945                die(_("No remote for the current branch."));
 946        if (!branch->merge_nr)
 947                die(_("No default upstream defined for the current branch."));
 948
 949        args = xcalloc(st_add(branch->merge_nr, 1), sizeof(char *));
 950        for (i = 0; i < branch->merge_nr; i++) {
 951                if (!branch->merge[i]->dst)
 952                        die(_("No remote-tracking branch for %s from %s"),
 953                            branch->merge[i]->src, branch->remote_name);
 954                args[i] = branch->merge[i]->dst;
 955        }
 956        args[i] = NULL;
 957        *argv = args;
 958        return i;
 959}
 960
 961static void write_merge_heads(struct commit_list *remoteheads)
 962{
 963        struct commit_list *j;
 964        struct strbuf buf = STRBUF_INIT;
 965
 966        for (j = remoteheads; j; j = j->next) {
 967                struct object_id *oid;
 968                struct commit *c = j->item;
 969                struct merge_remote_desc *desc;
 970
 971                desc = merge_remote_util(c);
 972                if (desc && desc->obj) {
 973                        oid = &desc->obj->oid;
 974                } else {
 975                        oid = &c->object.oid;
 976                }
 977                strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
 978        }
 979        write_file_buf(git_path_merge_head(the_repository), buf.buf, buf.len);
 980
 981        strbuf_reset(&buf);
 982        if (fast_forward == FF_NO)
 983                strbuf_addstr(&buf, "no-ff");
 984        write_file_buf(git_path_merge_mode(the_repository), buf.buf, buf.len);
 985        strbuf_release(&buf);
 986}
 987
 988static void write_merge_state(struct commit_list *remoteheads)
 989{
 990        write_merge_heads(remoteheads);
 991        strbuf_addch(&merge_msg, '\n');
 992        write_file_buf(git_path_merge_msg(the_repository), merge_msg.buf,
 993                       merge_msg.len);
 994}
 995
 996static int default_edit_option(void)
 997{
 998        static const char name[] = "GIT_MERGE_AUTOEDIT";
 999        const char *e = getenv(name);
1000        struct stat st_stdin, st_stdout;
1001
1002        if (have_message)
1003                /* an explicit -m msg without --[no-]edit */
1004                return 0;
1005
1006        if (e) {
1007                int v = git_parse_maybe_bool(e);
1008                if (v < 0)
1009                        die(_("Bad value '%s' in environment '%s'"), e, name);
1010                return v;
1011        }
1012
1013        /* Use editor if stdin and stdout are the same and is a tty */
1014        return (!fstat(0, &st_stdin) &&
1015                !fstat(1, &st_stdout) &&
1016                isatty(0) && isatty(1) &&
1017                st_stdin.st_dev == st_stdout.st_dev &&
1018                st_stdin.st_ino == st_stdout.st_ino &&
1019                st_stdin.st_mode == st_stdout.st_mode);
1020}
1021
1022static struct commit_list *reduce_parents(struct commit *head_commit,
1023                                          int *head_subsumed,
1024                                          struct commit_list *remoteheads)
1025{
1026        struct commit_list *parents, **remotes;
1027
1028        /*
1029         * Is the current HEAD reachable from another commit being
1030         * merged?  If so we do not want to record it as a parent of
1031         * the resulting merge, unless --no-ff is given.  We will flip
1032         * this variable to 0 when we find HEAD among the independent
1033         * tips being merged.
1034         */
1035        *head_subsumed = 1;
1036
1037        /* Find what parents to record by checking independent ones. */
1038        parents = reduce_heads(remoteheads);
1039        free_commit_list(remoteheads);
1040
1041        remoteheads = NULL;
1042        remotes = &remoteheads;
1043        while (parents) {
1044                struct commit *commit = pop_commit(&parents);
1045                if (commit == head_commit)
1046                        *head_subsumed = 0;
1047                else
1048                        remotes = &commit_list_insert(commit, remotes)->next;
1049        }
1050        return remoteheads;
1051}
1052
1053static void prepare_merge_message(struct strbuf *merge_names, struct strbuf *merge_msg)
1054{
1055        struct fmt_merge_msg_opts opts;
1056
1057        memset(&opts, 0, sizeof(opts));
1058        opts.add_title = !have_message;
1059        opts.shortlog_len = shortlog_len;
1060        opts.credit_people = (0 < option_edit);
1061
1062        fmt_merge_msg(merge_names, merge_msg, &opts);
1063        if (merge_msg->len)
1064                strbuf_setlen(merge_msg, merge_msg->len - 1);
1065}
1066
1067static void handle_fetch_head(struct commit_list **remotes, struct strbuf *merge_names)
1068{
1069        const char *filename;
1070        int fd, pos, npos;
1071        struct strbuf fetch_head_file = STRBUF_INIT;
1072        const unsigned hexsz = the_hash_algo->hexsz;
1073
1074        if (!merge_names)
1075                merge_names = &fetch_head_file;
1076
1077        filename = git_path_fetch_head(the_repository);
1078        fd = open(filename, O_RDONLY);
1079        if (fd < 0)
1080                die_errno(_("could not open '%s' for reading"), filename);
1081
1082        if (strbuf_read(merge_names, fd, 0) < 0)
1083                die_errno(_("could not read '%s'"), filename);
1084        if (close(fd) < 0)
1085                die_errno(_("could not close '%s'"), filename);
1086
1087        for (pos = 0; pos < merge_names->len; pos = npos) {
1088                struct object_id oid;
1089                char *ptr;
1090                struct commit *commit;
1091
1092                ptr = strchr(merge_names->buf + pos, '\n');
1093                if (ptr)
1094                        npos = ptr - merge_names->buf + 1;
1095                else
1096                        npos = merge_names->len;
1097
1098                if (npos - pos < hexsz + 2 ||
1099                    get_oid_hex(merge_names->buf + pos, &oid))
1100                        commit = NULL; /* bad */
1101                else if (memcmp(merge_names->buf + pos + hexsz, "\t\t", 2))
1102                        continue; /* not-for-merge */
1103                else {
1104                        char saved = merge_names->buf[pos + hexsz];
1105                        merge_names->buf[pos + hexsz] = '\0';
1106                        commit = get_merge_parent(merge_names->buf + pos);
1107                        merge_names->buf[pos + hexsz] = saved;
1108                }
1109                if (!commit) {
1110                        if (ptr)
1111                                *ptr = '\0';
1112                        die(_("not something we can merge in %s: %s"),
1113                            filename, merge_names->buf + pos);
1114                }
1115                remotes = &commit_list_insert(commit, remotes)->next;
1116        }
1117
1118        if (merge_names == &fetch_head_file)
1119                strbuf_release(&fetch_head_file);
1120}
1121
1122static struct commit_list *collect_parents(struct commit *head_commit,
1123                                           int *head_subsumed,
1124                                           int argc, const char **argv,
1125                                           struct strbuf *merge_msg)
1126{
1127        int i;
1128        struct commit_list *remoteheads = NULL;
1129        struct commit_list **remotes = &remoteheads;
1130        struct strbuf merge_names = STRBUF_INIT, *autogen = NULL;
1131
1132        if (merge_msg && (!have_message || shortlog_len))
1133                autogen = &merge_names;
1134
1135        if (head_commit)
1136                remotes = &commit_list_insert(head_commit, remotes)->next;
1137
1138        if (argc == 1 && !strcmp(argv[0], "FETCH_HEAD")) {
1139                handle_fetch_head(remotes, autogen);
1140                remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
1141        } else {
1142                for (i = 0; i < argc; i++) {
1143                        struct commit *commit = get_merge_parent(argv[i]);
1144                        if (!commit)
1145                                help_unknown_ref(argv[i], "merge",
1146                                                 _("not something we can merge"));
1147                        remotes = &commit_list_insert(commit, remotes)->next;
1148                }
1149                remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
1150                if (autogen) {
1151                        struct commit_list *p;
1152                        for (p = remoteheads; p; p = p->next)
1153                                merge_name(merge_remote_util(p->item)->name, autogen);
1154                }
1155        }
1156
1157        if (autogen) {
1158                prepare_merge_message(autogen, merge_msg);
1159                strbuf_release(autogen);
1160        }
1161
1162        return remoteheads;
1163}
1164
1165static int merging_a_throwaway_tag(struct commit *commit)
1166{
1167        char *tag_ref;
1168        struct object_id oid;
1169        int is_throwaway_tag = 0;
1170
1171        /* Are we merging a tag? */
1172        if (!merge_remote_util(commit) ||
1173            !merge_remote_util(commit)->obj ||
1174            merge_remote_util(commit)->obj->type != OBJ_TAG)
1175                return is_throwaway_tag;
1176
1177        /*
1178         * Now we know we are merging a tag object.  Are we downstream
1179         * and following the tags from upstream?  If so, we must have
1180         * the tag object pointed at by "refs/tags/$T" where $T is the
1181         * tagname recorded in the tag object.  We want to allow such
1182         * a "just to catch up" merge to fast-forward.
1183         *
1184         * Otherwise, we are playing an integrator's role, making a
1185         * merge with a throw-away tag from a contributor with
1186         * something like "git pull $contributor $signed_tag".
1187         * We want to forbid such a merge from fast-forwarding
1188         * by default; otherwise we would not keep the signature
1189         * anywhere.
1190         */
1191        tag_ref = xstrfmt("refs/tags/%s",
1192                          ((struct tag *)merge_remote_util(commit)->obj)->tag);
1193        if (!read_ref(tag_ref, &oid) &&
1194            oideq(&oid, &merge_remote_util(commit)->obj->oid))
1195                is_throwaway_tag = 0;
1196        else
1197                is_throwaway_tag = 1;
1198        free(tag_ref);
1199        return is_throwaway_tag;
1200}
1201
1202int cmd_merge(int argc, const char **argv, const char *prefix)
1203{
1204        struct object_id result_tree, stash, head_oid;
1205        struct commit *head_commit;
1206        struct strbuf buf = STRBUF_INIT;
1207        int i, ret = 0, head_subsumed;
1208        int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
1209        struct commit_list *common = NULL;
1210        const char *best_strategy = NULL, *wt_strategy = NULL;
1211        struct commit_list *remoteheads, *p;
1212        void *branch_to_free;
1213        int orig_argc = argc;
1214
1215        if (argc == 2 && !strcmp(argv[1], "-h"))
1216                usage_with_options(builtin_merge_usage, builtin_merge_options);
1217
1218        /*
1219         * Check if we are _not_ on a detached HEAD, i.e. if there is a
1220         * current branch.
1221         */
1222        branch = branch_to_free = resolve_refdup("HEAD", 0, &head_oid, NULL);
1223        if (branch)
1224                skip_prefix(branch, "refs/heads/", &branch);
1225
1226        init_diff_ui_defaults();
1227        git_config(git_merge_config, NULL);
1228
1229        if (!branch || is_null_oid(&head_oid))
1230                head_commit = NULL;
1231        else
1232                head_commit = lookup_commit_or_die(&head_oid, "HEAD");
1233
1234        if (branch_mergeoptions)
1235                parse_branch_merge_options(branch_mergeoptions);
1236        argc = parse_options(argc, argv, prefix, builtin_merge_options,
1237                        builtin_merge_usage, 0);
1238        if (shortlog_len < 0)
1239                shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;
1240
1241        if (verbosity < 0 && show_progress == -1)
1242                show_progress = 0;
1243
1244        if (abort_current_merge) {
1245                int nargc = 2;
1246                const char *nargv[] = {"reset", "--merge", NULL};
1247
1248                if (orig_argc != 2)
1249                        usage_msg_opt(_("--abort expects no arguments"),
1250                              builtin_merge_usage, builtin_merge_options);
1251
1252                if (!file_exists(git_path_merge_head(the_repository)))
1253                        die(_("There is no merge to abort (MERGE_HEAD missing)."));
1254
1255                /* Invoke 'git reset --merge' */
1256                ret = cmd_reset(nargc, nargv, prefix);
1257                goto done;
1258        }
1259
1260        if (continue_current_merge) {
1261                int nargc = 1;
1262                const char *nargv[] = {"commit", NULL};
1263
1264                if (orig_argc != 2)
1265                        usage_msg_opt(_("--continue expects no arguments"),
1266                              builtin_merge_usage, builtin_merge_options);
1267
1268                if (!file_exists(git_path_merge_head(the_repository)))
1269                        die(_("There is no merge in progress (MERGE_HEAD missing)."));
1270
1271                /* Invoke 'git commit' */
1272                ret = cmd_commit(nargc, nargv, prefix);
1273                goto done;
1274        }
1275
1276        if (read_cache_unmerged())
1277                die_resolve_conflict("merge");
1278
1279        if (file_exists(git_path_merge_head(the_repository))) {
1280                /*
1281                 * There is no unmerged entry, don't advise 'git
1282                 * add/rm <file>', just 'git commit'.
1283                 */
1284                if (advice_resolve_conflict)
1285                        die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1286                                  "Please, commit your changes before you merge."));
1287                else
1288                        die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1289        }
1290        if (file_exists(git_path_cherry_pick_head(the_repository))) {
1291                if (advice_resolve_conflict)
1292                        die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1293                            "Please, commit your changes before you merge."));
1294                else
1295                        die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
1296        }
1297        resolve_undo_clear();
1298
1299        if (verbosity < 0)
1300                show_diffstat = 0;
1301
1302        if (squash) {
1303                if (fast_forward == FF_NO)
1304                        die(_("You cannot combine --squash with --no-ff."));
1305                option_commit = 0;
1306        }
1307
1308        if (!argc) {
1309                if (default_to_upstream)
1310                        argc = setup_with_upstream(&argv);
1311                else
1312                        die(_("No commit specified and merge.defaultToUpstream not set."));
1313        } else if (argc == 1 && !strcmp(argv[0], "-")) {
1314                argv[0] = "@{-1}";
1315        }
1316
1317        if (!argc)
1318                usage_with_options(builtin_merge_usage,
1319                        builtin_merge_options);
1320
1321        if (!head_commit) {
1322                /*
1323                 * If the merged head is a valid one there is no reason
1324                 * to forbid "git merge" into a branch yet to be born.
1325                 * We do the same for "git pull".
1326                 */
1327                struct object_id *remote_head_oid;
1328                if (squash)
1329                        die(_("Squash commit into empty head not supported yet"));
1330                if (fast_forward == FF_NO)
1331                        die(_("Non-fast-forward commit does not make sense into "
1332                            "an empty head"));
1333                remoteheads = collect_parents(head_commit, &head_subsumed,
1334                                              argc, argv, NULL);
1335                if (!remoteheads)
1336                        die(_("%s - not something we can merge"), argv[0]);
1337                if (remoteheads->next)
1338                        die(_("Can merge only exactly one commit into empty head"));
1339                remote_head_oid = &remoteheads->item->object.oid;
1340                read_empty(remote_head_oid, 0);
1341                update_ref("initial pull", "HEAD", remote_head_oid, NULL, 0,
1342                           UPDATE_REFS_DIE_ON_ERR);
1343                goto done;
1344        }
1345
1346        /*
1347         * All the rest are the commits being merged; prepare
1348         * the standard merge summary message to be appended
1349         * to the given message.
1350         */
1351        remoteheads = collect_parents(head_commit, &head_subsumed,
1352                                      argc, argv, &merge_msg);
1353
1354        if (!head_commit || !argc)
1355                usage_with_options(builtin_merge_usage,
1356                        builtin_merge_options);
1357
1358        if (verify_signatures) {
1359                for (p = remoteheads; p; p = p->next) {
1360                        struct commit *commit = p->item;
1361                        char hex[GIT_MAX_HEXSZ + 1];
1362                        struct signature_check signature_check;
1363                        memset(&signature_check, 0, sizeof(signature_check));
1364
1365                        check_commit_signature(commit, &signature_check);
1366
1367                        find_unique_abbrev_r(hex, &commit->object.oid, DEFAULT_ABBREV);
1368                        switch (signature_check.result) {
1369                        case 'G':
1370                                break;
1371                        case 'U':
1372                                die(_("Commit %s has an untrusted GPG signature, "
1373                                      "allegedly by %s."), hex, signature_check.signer);
1374                        case 'B':
1375                                die(_("Commit %s has a bad GPG signature "
1376                                      "allegedly by %s."), hex, signature_check.signer);
1377                        default: /* 'N' */
1378                                die(_("Commit %s does not have a GPG signature."), hex);
1379                        }
1380                        if (verbosity >= 0 && signature_check.result == 'G')
1381                                printf(_("Commit %s has a good GPG signature by %s\n"),
1382                                       hex, signature_check.signer);
1383
1384                        signature_check_clear(&signature_check);
1385                }
1386        }
1387
1388        strbuf_addstr(&buf, "merge");
1389        for (p = remoteheads; p; p = p->next)
1390                strbuf_addf(&buf, " %s", merge_remote_util(p->item)->name);
1391        setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1392        strbuf_reset(&buf);
1393
1394        for (p = remoteheads; p; p = p->next) {
1395                struct commit *commit = p->item;
1396                strbuf_addf(&buf, "GITHEAD_%s",
1397                            oid_to_hex(&commit->object.oid));
1398                setenv(buf.buf, merge_remote_util(commit)->name, 1);
1399                strbuf_reset(&buf);
1400                if (fast_forward != FF_ONLY && merging_a_throwaway_tag(commit))
1401                        fast_forward = FF_NO;
1402        }
1403
1404        if (option_edit < 0)
1405                option_edit = default_edit_option();
1406
1407        if (!use_strategies) {
1408                if (!remoteheads)
1409                        ; /* already up-to-date */
1410                else if (!remoteheads->next)
1411                        add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1412                else
1413                        add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1414        }
1415
1416        for (i = 0; i < use_strategies_nr; i++) {
1417                if (use_strategies[i]->attr & NO_FAST_FORWARD)
1418                        fast_forward = FF_NO;
1419                if (use_strategies[i]->attr & NO_TRIVIAL)
1420                        allow_trivial = 0;
1421        }
1422
1423        if (!remoteheads)
1424                ; /* already up-to-date */
1425        else if (!remoteheads->next)
1426                common = get_merge_bases(head_commit, remoteheads->item);
1427        else {
1428                struct commit_list *list = remoteheads;
1429                commit_list_insert(head_commit, &list);
1430                common = get_octopus_merge_bases(list);
1431                free(list);
1432        }
1433
1434        update_ref("updating ORIG_HEAD", "ORIG_HEAD",
1435                   &head_commit->object.oid, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
1436
1437        if (remoteheads && !common) {
1438                /* No common ancestors found. */
1439                if (!allow_unrelated_histories)
1440                        die(_("refusing to merge unrelated histories"));
1441                /* otherwise, we need a real merge. */
1442        } else if (!remoteheads ||
1443                 (!remoteheads->next && !common->next &&
1444                  common->item == remoteheads->item)) {
1445                /*
1446                 * If head can reach all the merge then we are up to date.
1447                 * but first the most common case of merging one remote.
1448                 */
1449                finish_up_to_date(_("Already up to date."));
1450                goto done;
1451        } else if (fast_forward != FF_NO && !remoteheads->next &&
1452                        !common->next &&
1453                        oideq(&common->item->object.oid, &head_commit->object.oid)) {
1454                /* Again the most common case of merging one remote. */
1455                struct strbuf msg = STRBUF_INIT;
1456                struct commit *commit;
1457
1458                if (verbosity >= 0) {
1459                        printf(_("Updating %s..%s\n"),
1460                               find_unique_abbrev(&head_commit->object.oid,
1461                                                  DEFAULT_ABBREV),
1462                               find_unique_abbrev(&remoteheads->item->object.oid,
1463                                                  DEFAULT_ABBREV));
1464                }
1465                strbuf_addstr(&msg, "Fast-forward");
1466                if (have_message)
1467                        strbuf_addstr(&msg,
1468                                " (no commit created; -m option ignored)");
1469                commit = remoteheads->item;
1470                if (!commit) {
1471                        ret = 1;
1472                        goto done;
1473                }
1474
1475                if (checkout_fast_forward(the_repository,
1476                                          &head_commit->object.oid,
1477                                          &commit->object.oid,
1478                                          overwrite_ignore)) {
1479                        ret = 1;
1480                        goto done;
1481                }
1482
1483                finish(head_commit, remoteheads, &commit->object.oid, msg.buf);
1484                drop_save();
1485                goto done;
1486        } else if (!remoteheads->next && common->next)
1487                ;
1488                /*
1489                 * We are not doing octopus and not fast-forward.  Need
1490                 * a real merge.
1491                 */
1492        else if (!remoteheads->next && !common->next && option_commit) {
1493                /*
1494                 * We are not doing octopus, not fast-forward, and have
1495                 * only one common.
1496                 */
1497                refresh_cache(REFRESH_QUIET);
1498                if (allow_trivial && fast_forward != FF_ONLY) {
1499                        /* See if it is really trivial. */
1500                        git_committer_info(IDENT_STRICT);
1501                        printf(_("Trying really trivial in-index merge...\n"));
1502                        if (!read_tree_trivial(&common->item->object.oid,
1503                                               &head_commit->object.oid,
1504                                               &remoteheads->item->object.oid)) {
1505                                ret = merge_trivial(head_commit, remoteheads);
1506                                goto done;
1507                        }
1508                        printf(_("Nope.\n"));
1509                }
1510        } else {
1511                /*
1512                 * An octopus.  If we can reach all the remote we are up
1513                 * to date.
1514                 */
1515                int up_to_date = 1;
1516                struct commit_list *j;
1517
1518                for (j = remoteheads; j; j = j->next) {
1519                        struct commit_list *common_one;
1520
1521                        /*
1522                         * Here we *have* to calculate the individual
1523                         * merge_bases again, otherwise "git merge HEAD^
1524                         * HEAD^^" would be missed.
1525                         */
1526                        common_one = get_merge_bases(head_commit, j->item);
1527                        if (!oideq(&common_one->item->object.oid, &j->item->object.oid)) {
1528                                up_to_date = 0;
1529                                break;
1530                        }
1531                }
1532                if (up_to_date) {
1533                        finish_up_to_date(_("Already up to date. Yeeah!"));
1534                        goto done;
1535                }
1536        }
1537
1538        if (fast_forward == FF_ONLY)
1539                die(_("Not possible to fast-forward, aborting."));
1540
1541        /* We are going to make a new commit. */
1542        git_committer_info(IDENT_STRICT);
1543
1544        /*
1545         * At this point, we need a real merge.  No matter what strategy
1546         * we use, it would operate on the index, possibly affecting the
1547         * working tree, and when resolved cleanly, have the desired
1548         * tree in the index -- this means that the index must be in
1549         * sync with the head commit.  The strategies are responsible
1550         * to ensure this.
1551         */
1552        if (use_strategies_nr == 1 ||
1553            /*
1554             * Stash away the local changes so that we can try more than one.
1555             */
1556            save_state(&stash))
1557                oidclr(&stash);
1558
1559        for (i = 0; i < use_strategies_nr; i++) {
1560                int ret;
1561                if (i) {
1562                        printf(_("Rewinding the tree to pristine...\n"));
1563                        restore_state(&head_commit->object.oid, &stash);
1564                }
1565                if (use_strategies_nr != 1)
1566                        printf(_("Trying merge strategy %s...\n"),
1567                                use_strategies[i]->name);
1568                /*
1569                 * Remember which strategy left the state in the working
1570                 * tree.
1571                 */
1572                wt_strategy = use_strategies[i]->name;
1573
1574                ret = try_merge_strategy(use_strategies[i]->name,
1575                                         common, remoteheads,
1576                                         head_commit);
1577                if (!option_commit && !ret) {
1578                        merge_was_ok = 1;
1579                        /*
1580                         * This is necessary here just to avoid writing
1581                         * the tree, but later we will *not* exit with
1582                         * status code 1 because merge_was_ok is set.
1583                         */
1584                        ret = 1;
1585                }
1586
1587                if (ret) {
1588                        /*
1589                         * The backend exits with 1 when conflicts are
1590                         * left to be resolved, with 2 when it does not
1591                         * handle the given merge at all.
1592                         */
1593                        if (ret == 1) {
1594                                int cnt = evaluate_result();
1595
1596                                if (best_cnt <= 0 || cnt <= best_cnt) {
1597                                        best_strategy = use_strategies[i]->name;
1598                                        best_cnt = cnt;
1599                                }
1600                        }
1601                        if (merge_was_ok)
1602                                break;
1603                        else
1604                                continue;
1605                }
1606
1607                /* Automerge succeeded. */
1608                write_tree_trivial(&result_tree);
1609                automerge_was_ok = 1;
1610                break;
1611        }
1612
1613        /*
1614         * If we have a resulting tree, that means the strategy module
1615         * auto resolved the merge cleanly.
1616         */
1617        if (automerge_was_ok) {
1618                ret = finish_automerge(head_commit, head_subsumed,
1619                                       common, remoteheads,
1620                                       &result_tree, wt_strategy);
1621                goto done;
1622        }
1623
1624        /*
1625         * Pick the result from the best strategy and have the user fix
1626         * it up.
1627         */
1628        if (!best_strategy) {
1629                restore_state(&head_commit->object.oid, &stash);
1630                if (use_strategies_nr > 1)
1631                        fprintf(stderr,
1632                                _("No merge strategy handled the merge.\n"));
1633                else
1634                        fprintf(stderr, _("Merge with strategy %s failed.\n"),
1635                                use_strategies[0]->name);
1636                ret = 2;
1637                goto done;
1638        } else if (best_strategy == wt_strategy)
1639                ; /* We already have its result in the working tree. */
1640        else {
1641                printf(_("Rewinding the tree to pristine...\n"));
1642                restore_state(&head_commit->object.oid, &stash);
1643                printf(_("Using the %s to prepare resolving by hand.\n"),
1644                        best_strategy);
1645                try_merge_strategy(best_strategy, common, remoteheads,
1646                                   head_commit);
1647        }
1648
1649        if (squash)
1650                finish(head_commit, remoteheads, NULL, NULL);
1651        else
1652                write_merge_state(remoteheads);
1653
1654        if (merge_was_ok)
1655                fprintf(stderr, _("Automatic merge went well; "
1656                        "stopped before committing as requested\n"));
1657        else
1658                ret = suggest_conflicts();
1659
1660done:
1661        free(branch_to_free);
1662        return ret;
1663}