builtin / merge.con commit index-pack: work around thread-unsafe pread() (3953949)
   1/*
   2 * Builtin "git merge"
   3 *
   4 * Copyright (c) 2008 Miklos Vajna <vmiklos@frugalware.org>
   5 *
   6 * Based on git-merge.sh by Junio C Hamano.
   7 */
   8
   9#include "cache.h"
  10#include "parse-options.h"
  11#include "builtin.h"
  12#include "run-command.h"
  13#include "diff.h"
  14#include "refs.h"
  15#include "commit.h"
  16#include "diffcore.h"
  17#include "revision.h"
  18#include "unpack-trees.h"
  19#include "cache-tree.h"
  20#include "dir.h"
  21#include "utf8.h"
  22#include "log-tree.h"
  23#include "color.h"
  24#include "rerere.h"
  25#include "help.h"
  26#include "merge-recursive.h"
  27#include "resolve-undo.h"
  28#include "remote.h"
  29#include "fmt-merge-msg.h"
  30#include "gpg-interface.h"
  31
  32#define DEFAULT_TWOHEAD (1<<0)
  33#define DEFAULT_OCTOPUS (1<<1)
  34#define NO_FAST_FORWARD (1<<2)
  35#define NO_TRIVIAL      (1<<3)
  36
  37struct strategy {
  38        const char *name;
  39        unsigned attr;
  40};
  41
  42static const char * const builtin_merge_usage[] = {
  43        N_("git merge [options] [<commit>...]"),
  44        N_("git merge [options] <msg> HEAD <commit>"),
  45        N_("git merge --abort"),
  46        NULL
  47};
  48
  49static int show_diffstat = 1, shortlog_len = -1, squash;
  50static int option_commit = 1;
  51static int option_edit = -1;
  52static int allow_trivial = 1, have_message, verify_signatures;
  53static int overwrite_ignore = 1;
  54static struct strbuf merge_msg = STRBUF_INIT;
  55static struct strategy **use_strategies;
  56static size_t use_strategies_nr, use_strategies_alloc;
  57static const char **xopts;
  58static size_t xopts_nr, xopts_alloc;
  59static const char *branch;
  60static char *branch_mergeoptions;
  61static int option_renormalize;
  62static int verbosity;
  63static int allow_rerere_auto;
  64static int abort_current_merge;
  65static int show_progress = -1;
  66static int default_to_upstream;
  67static const char *sign_commit;
  68
  69static struct strategy all_strategy[] = {
  70        { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
  71        { "octopus",    DEFAULT_OCTOPUS },
  72        { "resolve",    0 },
  73        { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
  74        { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
  75};
  76
  77static const char *pull_twohead, *pull_octopus;
  78
  79enum ff_type {
  80        FF_NO,
  81        FF_ALLOW,
  82        FF_ONLY
  83};
  84
  85static enum ff_type fast_forward = FF_ALLOW;
  86
  87static int option_parse_message(const struct option *opt,
  88                                const char *arg, int unset)
  89{
  90        struct strbuf *buf = opt->value;
  91
  92        if (unset)
  93                strbuf_setlen(buf, 0);
  94        else if (arg) {
  95                strbuf_addf(buf, "%s%s", buf->len ? "\n\n" : "", arg);
  96                have_message = 1;
  97        } else
  98                return error(_("switch `m' requires a value"));
  99        return 0;
 100}
 101
 102static struct strategy *get_strategy(const char *name)
 103{
 104        int i;
 105        struct strategy *ret;
 106        static struct cmdnames main_cmds, other_cmds;
 107        static int loaded;
 108
 109        if (!name)
 110                return NULL;
 111
 112        for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 113                if (!strcmp(name, all_strategy[i].name))
 114                        return &all_strategy[i];
 115
 116        if (!loaded) {
 117                struct cmdnames not_strategies;
 118                loaded = 1;
 119
 120                memset(&not_strategies, 0, sizeof(struct cmdnames));
 121                load_command_list("git-merge-", &main_cmds, &other_cmds);
 122                for (i = 0; i < main_cmds.cnt; i++) {
 123                        int j, found = 0;
 124                        struct cmdname *ent = main_cmds.names[i];
 125                        for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
 126                                if (!strncmp(ent->name, all_strategy[j].name, ent->len)
 127                                                && !all_strategy[j].name[ent->len])
 128                                        found = 1;
 129                        if (!found)
 130                                add_cmdname(&not_strategies, ent->name, ent->len);
 131                }
 132                exclude_cmds(&main_cmds, &not_strategies);
 133        }
 134        if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
 135                fprintf(stderr, _("Could not find merge strategy '%s'.\n"), name);
 136                fprintf(stderr, _("Available strategies are:"));
 137                for (i = 0; i < main_cmds.cnt; i++)
 138                        fprintf(stderr, " %s", main_cmds.names[i]->name);
 139                fprintf(stderr, ".\n");
 140                if (other_cmds.cnt) {
 141                        fprintf(stderr, _("Available custom strategies are:"));
 142                        for (i = 0; i < other_cmds.cnt; i++)
 143                                fprintf(stderr, " %s", other_cmds.names[i]->name);
 144                        fprintf(stderr, ".\n");
 145                }
 146                exit(1);
 147        }
 148
 149        ret = xcalloc(1, sizeof(struct strategy));
 150        ret->name = xstrdup(name);
 151        ret->attr = NO_TRIVIAL;
 152        return ret;
 153}
 154
 155static void append_strategy(struct strategy *s)
 156{
 157        ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
 158        use_strategies[use_strategies_nr++] = s;
 159}
 160
 161static int option_parse_strategy(const struct option *opt,
 162                                 const char *name, int unset)
 163{
 164        if (unset)
 165                return 0;
 166
 167        append_strategy(get_strategy(name));
 168        return 0;
 169}
 170
 171static int option_parse_x(const struct option *opt,
 172                          const char *arg, int unset)
 173{
 174        if (unset)
 175                return 0;
 176
 177        ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
 178        xopts[xopts_nr++] = xstrdup(arg);
 179        return 0;
 180}
 181
 182static int option_parse_n(const struct option *opt,
 183                          const char *arg, int unset)
 184{
 185        show_diffstat = unset;
 186        return 0;
 187}
 188
 189static struct option builtin_merge_options[] = {
 190        { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
 191                N_("do not show a diffstat at the end of the merge"),
 192                PARSE_OPT_NOARG, option_parse_n },
 193        OPT_BOOL(0, "stat", &show_diffstat,
 194                N_("show a diffstat at the end of the merge")),
 195        OPT_BOOL(0, "summary", &show_diffstat, N_("(synonym to --stat)")),
 196        { OPTION_INTEGER, 0, "log", &shortlog_len, N_("n"),
 197          N_("add (at most <n>) entries from shortlog to merge commit message"),
 198          PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
 199        OPT_BOOL(0, "squash", &squash,
 200                N_("create a single commit instead of doing a merge")),
 201        OPT_BOOL(0, "commit", &option_commit,
 202                N_("perform a commit if the merge succeeds (default)")),
 203        OPT_BOOL('e', "edit", &option_edit,
 204                N_("edit message before committing")),
 205        OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
 206        { OPTION_SET_INT, 0, "ff-only", &fast_forward, NULL,
 207                N_("abort if fast-forward is not possible"),
 208                PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, FF_ONLY },
 209        OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
 210        OPT_BOOL(0, "verify-signatures", &verify_signatures,
 211                N_("Verify that the named commit has a valid GPG signature")),
 212        OPT_CALLBACK('s', "strategy", &use_strategies, N_("strategy"),
 213                N_("merge strategy to use"), option_parse_strategy),
 214        OPT_CALLBACK('X', "strategy-option", &xopts, N_("option=value"),
 215                N_("option for selected merge strategy"), option_parse_x),
 216        OPT_CALLBACK('m', "message", &merge_msg, N_("message"),
 217                N_("merge commit message (for a non-fast-forward merge)"),
 218                option_parse_message),
 219        OPT__VERBOSITY(&verbosity),
 220        OPT_BOOL(0, "abort", &abort_current_merge,
 221                N_("abort the current in-progress merge")),
 222        OPT_SET_INT(0, "progress", &show_progress, N_("force progress reporting"), 1),
 223        { OPTION_STRING, 'S', "gpg-sign", &sign_commit, N_("key id"),
 224          N_("GPG sign commit"), PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
 225        OPT_BOOL(0, "overwrite-ignore", &overwrite_ignore, N_("update ignored files (default)")),
 226        OPT_END()
 227};
 228
 229/* Cleans up metadata that is uninteresting after a succeeded merge. */
 230static void drop_save(void)
 231{
 232        unlink(git_path("MERGE_HEAD"));
 233        unlink(git_path("MERGE_MSG"));
 234        unlink(git_path("MERGE_MODE"));
 235}
 236
 237static int save_state(unsigned char *stash)
 238{
 239        int len;
 240        struct child_process cp;
 241        struct strbuf buffer = STRBUF_INIT;
 242        const char *argv[] = {"stash", "create", NULL};
 243
 244        memset(&cp, 0, sizeof(cp));
 245        cp.argv = argv;
 246        cp.out = -1;
 247        cp.git_cmd = 1;
 248
 249        if (start_command(&cp))
 250                die(_("could not run stash."));
 251        len = strbuf_read(&buffer, cp.out, 1024);
 252        close(cp.out);
 253
 254        if (finish_command(&cp) || len < 0)
 255                die(_("stash failed"));
 256        else if (!len)          /* no changes */
 257                return -1;
 258        strbuf_setlen(&buffer, buffer.len-1);
 259        if (get_sha1(buffer.buf, stash))
 260                die(_("not a valid object: %s"), buffer.buf);
 261        return 0;
 262}
 263
 264static void read_empty(unsigned const char *sha1, int verbose)
 265{
 266        int i = 0;
 267        const char *args[7];
 268
 269        args[i++] = "read-tree";
 270        if (verbose)
 271                args[i++] = "-v";
 272        args[i++] = "-m";
 273        args[i++] = "-u";
 274        args[i++] = EMPTY_TREE_SHA1_HEX;
 275        args[i++] = sha1_to_hex(sha1);
 276        args[i] = NULL;
 277
 278        if (run_command_v_opt(args, RUN_GIT_CMD))
 279                die(_("read-tree failed"));
 280}
 281
 282static void reset_hard(unsigned const char *sha1, int verbose)
 283{
 284        int i = 0;
 285        const char *args[6];
 286
 287        args[i++] = "read-tree";
 288        if (verbose)
 289                args[i++] = "-v";
 290        args[i++] = "--reset";
 291        args[i++] = "-u";
 292        args[i++] = sha1_to_hex(sha1);
 293        args[i] = NULL;
 294
 295        if (run_command_v_opt(args, RUN_GIT_CMD))
 296                die(_("read-tree failed"));
 297}
 298
 299static void restore_state(const unsigned char *head,
 300                          const unsigned char *stash)
 301{
 302        struct strbuf sb = STRBUF_INIT;
 303        const char *args[] = { "stash", "apply", NULL, NULL };
 304
 305        if (is_null_sha1(stash))
 306                return;
 307
 308        reset_hard(head, 1);
 309
 310        args[2] = sha1_to_hex(stash);
 311
 312        /*
 313         * It is OK to ignore error here, for example when there was
 314         * nothing to restore.
 315         */
 316        run_command_v_opt(args, RUN_GIT_CMD);
 317
 318        strbuf_release(&sb);
 319        refresh_cache(REFRESH_QUIET);
 320}
 321
 322/* This is called when no merge was necessary. */
 323static void finish_up_to_date(const char *msg)
 324{
 325        if (verbosity >= 0)
 326                printf("%s%s\n", squash ? _(" (nothing to squash)") : "", msg);
 327        drop_save();
 328}
 329
 330static void squash_message(struct commit *commit, struct commit_list *remoteheads)
 331{
 332        struct rev_info rev;
 333        struct strbuf out = STRBUF_INIT;
 334        struct commit_list *j;
 335        const char *filename;
 336        int fd;
 337        struct pretty_print_context ctx = {0};
 338
 339        printf(_("Squash commit -- not updating HEAD\n"));
 340        filename = git_path("SQUASH_MSG");
 341        fd = open(filename, O_WRONLY | O_CREAT, 0666);
 342        if (fd < 0)
 343                die_errno(_("Could not write to '%s'"), filename);
 344
 345        init_revisions(&rev, NULL);
 346        rev.ignore_merges = 1;
 347        rev.commit_format = CMIT_FMT_MEDIUM;
 348
 349        commit->object.flags |= UNINTERESTING;
 350        add_pending_object(&rev, &commit->object, NULL);
 351
 352        for (j = remoteheads; j; j = j->next)
 353                add_pending_object(&rev, &j->item->object, NULL);
 354
 355        setup_revisions(0, NULL, &rev, NULL);
 356        if (prepare_revision_walk(&rev))
 357                die(_("revision walk setup failed"));
 358
 359        ctx.abbrev = rev.abbrev;
 360        ctx.date_mode = rev.date_mode;
 361        ctx.fmt = rev.commit_format;
 362
 363        strbuf_addstr(&out, "Squashed commit of the following:\n");
 364        while ((commit = get_revision(&rev)) != NULL) {
 365                strbuf_addch(&out, '\n');
 366                strbuf_addf(&out, "commit %s\n",
 367                        sha1_to_hex(commit->object.sha1));
 368                pretty_print_commit(&ctx, commit, &out);
 369        }
 370        if (write_in_full(fd, out.buf, out.len) != out.len)
 371                die_errno(_("Writing SQUASH_MSG"));
 372        if (close(fd))
 373                die_errno(_("Finishing SQUASH_MSG"));
 374        strbuf_release(&out);
 375}
 376
 377static void finish(struct commit *head_commit,
 378                   struct commit_list *remoteheads,
 379                   const unsigned char *new_head, const char *msg)
 380{
 381        struct strbuf reflog_message = STRBUF_INIT;
 382        const unsigned char *head = head_commit->object.sha1;
 383
 384        if (!msg)
 385                strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
 386        else {
 387                if (verbosity >= 0)
 388                        printf("%s\n", msg);
 389                strbuf_addf(&reflog_message, "%s: %s",
 390                        getenv("GIT_REFLOG_ACTION"), msg);
 391        }
 392        if (squash) {
 393                squash_message(head_commit, remoteheads);
 394        } else {
 395                if (verbosity >= 0 && !merge_msg.len)
 396                        printf(_("No merge message -- not updating HEAD\n"));
 397                else {
 398                        const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 399                        update_ref(reflog_message.buf, "HEAD",
 400                                new_head, head, 0,
 401                                DIE_ON_ERR);
 402                        /*
 403                         * We ignore errors in 'gc --auto', since the
 404                         * user should see them.
 405                         */
 406                        run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 407                }
 408        }
 409        if (new_head && show_diffstat) {
 410                struct diff_options opts;
 411                diff_setup(&opts);
 412                opts.stat_width = -1; /* use full terminal width */
 413                opts.stat_graph_width = -1; /* respect statGraphWidth config */
 414                opts.output_format |=
 415                        DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 416                opts.detect_rename = DIFF_DETECT_RENAME;
 417                diff_setup_done(&opts);
 418                diff_tree_sha1(head, new_head, "", &opts);
 419                diffcore_std(&opts);
 420                diff_flush(&opts);
 421        }
 422
 423        /* Run a post-merge hook */
 424        run_hook(NULL, "post-merge", squash ? "1" : "0", NULL);
 425
 426        strbuf_release(&reflog_message);
 427}
 428
 429/* Get the name for the merge commit's message. */
 430static void merge_name(const char *remote, struct strbuf *msg)
 431{
 432        struct commit *remote_head;
 433        unsigned char branch_head[20];
 434        struct strbuf buf = STRBUF_INIT;
 435        struct strbuf bname = STRBUF_INIT;
 436        const char *ptr;
 437        char *found_ref;
 438        int len, early;
 439
 440        strbuf_branchname(&bname, remote);
 441        remote = bname.buf;
 442
 443        memset(branch_head, 0, sizeof(branch_head));
 444        remote_head = get_merge_parent(remote);
 445        if (!remote_head)
 446                die(_("'%s' does not point to a commit"), remote);
 447
 448        if (dwim_ref(remote, strlen(remote), branch_head, &found_ref) > 0) {
 449                if (starts_with(found_ref, "refs/heads/")) {
 450                        strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 451                                    sha1_to_hex(branch_head), remote);
 452                        goto cleanup;
 453                }
 454                if (starts_with(found_ref, "refs/tags/")) {
 455                        strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
 456                                    sha1_to_hex(branch_head), remote);
 457                        goto cleanup;
 458                }
 459                if (starts_with(found_ref, "refs/remotes/")) {
 460                        strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
 461                                    sha1_to_hex(branch_head), remote);
 462                        goto cleanup;
 463                }
 464        }
 465
 466        /* See if remote matches <name>^^^.. or <name>~<number> */
 467        for (len = 0, ptr = remote + strlen(remote);
 468             remote < ptr && ptr[-1] == '^';
 469             ptr--)
 470                len++;
 471        if (len)
 472                early = 1;
 473        else {
 474                early = 0;
 475                ptr = strrchr(remote, '~');
 476                if (ptr) {
 477                        int seen_nonzero = 0;
 478
 479                        len++; /* count ~ */
 480                        while (*++ptr && isdigit(*ptr)) {
 481                                seen_nonzero |= (*ptr != '0');
 482                                len++;
 483                        }
 484                        if (*ptr)
 485                                len = 0; /* not ...~<number> */
 486                        else if (seen_nonzero)
 487                                early = 1;
 488                        else if (len == 1)
 489                                early = 1; /* "name~" is "name~1"! */
 490                }
 491        }
 492        if (len) {
 493                struct strbuf truname = STRBUF_INIT;
 494                strbuf_addstr(&truname, "refs/heads/");
 495                strbuf_addstr(&truname, remote);
 496                strbuf_setlen(&truname, truname.len - len);
 497                if (ref_exists(truname.buf)) {
 498                        strbuf_addf(msg,
 499                                    "%s\t\tbranch '%s'%s of .\n",
 500                                    sha1_to_hex(remote_head->object.sha1),
 501                                    truname.buf + 11,
 502                                    (early ? " (early part)" : ""));
 503                        strbuf_release(&truname);
 504                        goto cleanup;
 505                }
 506        }
 507
 508        if (!strcmp(remote, "FETCH_HEAD") &&
 509                        !access(git_path("FETCH_HEAD"), R_OK)) {
 510                const char *filename;
 511                FILE *fp;
 512                struct strbuf line = STRBUF_INIT;
 513                char *ptr;
 514
 515                filename = git_path("FETCH_HEAD");
 516                fp = fopen(filename, "r");
 517                if (!fp)
 518                        die_errno(_("could not open '%s' for reading"),
 519                                  filename);
 520                strbuf_getline(&line, fp, '\n');
 521                fclose(fp);
 522                ptr = strstr(line.buf, "\tnot-for-merge\t");
 523                if (ptr)
 524                        strbuf_remove(&line, ptr-line.buf+1, 13);
 525                strbuf_addbuf(msg, &line);
 526                strbuf_release(&line);
 527                goto cleanup;
 528        }
 529
 530        if (remote_head->util) {
 531                struct merge_remote_desc *desc;
 532                desc = merge_remote_util(remote_head);
 533                if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
 534                        strbuf_addf(msg, "%s\t\t%s '%s'\n",
 535                                    sha1_to_hex(desc->obj->sha1),
 536                                    typename(desc->obj->type),
 537                                    remote);
 538                        goto cleanup;
 539                }
 540        }
 541
 542        strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 543                sha1_to_hex(remote_head->object.sha1), remote);
 544cleanup:
 545        strbuf_release(&buf);
 546        strbuf_release(&bname);
 547}
 548
 549static void parse_branch_merge_options(char *bmo)
 550{
 551        const char **argv;
 552        int argc;
 553
 554        if (!bmo)
 555                return;
 556        argc = split_cmdline(bmo, &argv);
 557        if (argc < 0)
 558                die(_("Bad branch.%s.mergeoptions string: %s"), branch,
 559                    split_cmdline_strerror(argc));
 560        argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
 561        memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
 562        argc++;
 563        argv[0] = "branch.*.mergeoptions";
 564        parse_options(argc, argv, NULL, builtin_merge_options,
 565                      builtin_merge_usage, 0);
 566        free(argv);
 567}
 568
 569static int git_merge_config(const char *k, const char *v, void *cb)
 570{
 571        int status;
 572
 573        if (branch && starts_with(k, "branch.") &&
 574                starts_with(k + 7, branch) &&
 575                !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
 576                free(branch_mergeoptions);
 577                branch_mergeoptions = xstrdup(v);
 578                return 0;
 579        }
 580
 581        if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 582                show_diffstat = git_config_bool(k, v);
 583        else if (!strcmp(k, "pull.twohead"))
 584                return git_config_string(&pull_twohead, k, v);
 585        else if (!strcmp(k, "pull.octopus"))
 586                return git_config_string(&pull_octopus, k, v);
 587        else if (!strcmp(k, "merge.renormalize"))
 588                option_renormalize = git_config_bool(k, v);
 589        else if (!strcmp(k, "merge.ff")) {
 590                int boolval = git_config_maybe_bool(k, v);
 591                if (0 <= boolval) {
 592                        fast_forward = boolval ? FF_ALLOW : FF_NO;
 593                } else if (v && !strcmp(v, "only")) {
 594                        fast_forward = FF_ONLY;
 595                } /* do not barf on values from future versions of git */
 596                return 0;
 597        } else if (!strcmp(k, "merge.defaulttoupstream")) {
 598                default_to_upstream = git_config_bool(k, v);
 599                return 0;
 600        }
 601
 602        status = fmt_merge_msg_config(k, v, cb);
 603        if (status)
 604                return status;
 605        status = git_gpg_config(k, v, NULL);
 606        if (status)
 607                return status;
 608        return git_diff_ui_config(k, v, cb);
 609}
 610
 611static int read_tree_trivial(unsigned char *common, unsigned char *head,
 612                             unsigned char *one)
 613{
 614        int i, nr_trees = 0;
 615        struct tree *trees[MAX_UNPACK_TREES];
 616        struct tree_desc t[MAX_UNPACK_TREES];
 617        struct unpack_trees_options opts;
 618
 619        memset(&opts, 0, sizeof(opts));
 620        opts.head_idx = 2;
 621        opts.src_index = &the_index;
 622        opts.dst_index = &the_index;
 623        opts.update = 1;
 624        opts.verbose_update = 1;
 625        opts.trivial_merges_only = 1;
 626        opts.merge = 1;
 627        trees[nr_trees] = parse_tree_indirect(common);
 628        if (!trees[nr_trees++])
 629                return -1;
 630        trees[nr_trees] = parse_tree_indirect(head);
 631        if (!trees[nr_trees++])
 632                return -1;
 633        trees[nr_trees] = parse_tree_indirect(one);
 634        if (!trees[nr_trees++])
 635                return -1;
 636        opts.fn = threeway_merge;
 637        cache_tree_free(&active_cache_tree);
 638        for (i = 0; i < nr_trees; i++) {
 639                parse_tree(trees[i]);
 640                init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 641        }
 642        if (unpack_trees(nr_trees, t, &opts))
 643                return -1;
 644        return 0;
 645}
 646
 647static void write_tree_trivial(unsigned char *sha1)
 648{
 649        if (write_cache_as_tree(sha1, 0, NULL))
 650                die(_("git write-tree failed to write a tree"));
 651}
 652
 653static int try_merge_strategy(const char *strategy, struct commit_list *common,
 654                              struct commit_list *remoteheads,
 655                              struct commit *head, const char *head_arg)
 656{
 657        int index_fd;
 658        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 659
 660        index_fd = hold_locked_index(lock, 1);
 661        refresh_cache(REFRESH_QUIET);
 662        if (active_cache_changed &&
 663                        (write_cache(index_fd, active_cache, active_nr) ||
 664                         commit_locked_index(lock)))
 665                return error(_("Unable to write index."));
 666        rollback_lock_file(lock);
 667
 668        if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
 669                int clean, x;
 670                struct commit *result;
 671                struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 672                int index_fd;
 673                struct commit_list *reversed = NULL;
 674                struct merge_options o;
 675                struct commit_list *j;
 676
 677                if (remoteheads->next) {
 678                        error(_("Not handling anything other than two heads merge."));
 679                        return 2;
 680                }
 681
 682                init_merge_options(&o);
 683                if (!strcmp(strategy, "subtree"))
 684                        o.subtree_shift = "";
 685
 686                o.renormalize = option_renormalize;
 687                o.show_rename_progress =
 688                        show_progress == -1 ? isatty(2) : show_progress;
 689
 690                for (x = 0; x < xopts_nr; x++)
 691                        if (parse_merge_opt(&o, xopts[x]))
 692                                die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
 693
 694                o.branch1 = head_arg;
 695                o.branch2 = merge_remote_util(remoteheads->item)->name;
 696
 697                for (j = common; j; j = j->next)
 698                        commit_list_insert(j->item, &reversed);
 699
 700                index_fd = hold_locked_index(lock, 1);
 701                clean = merge_recursive(&o, head,
 702                                remoteheads->item, reversed, &result);
 703                if (active_cache_changed &&
 704                                (write_cache(index_fd, active_cache, active_nr) ||
 705                                 commit_locked_index(lock)))
 706                        die (_("unable to write %s"), get_index_file());
 707                rollback_lock_file(lock);
 708                return clean ? 0 : 1;
 709        } else {
 710                return try_merge_command(strategy, xopts_nr, xopts,
 711                                                common, head_arg, remoteheads);
 712        }
 713}
 714
 715static void count_diff_files(struct diff_queue_struct *q,
 716                             struct diff_options *opt, void *data)
 717{
 718        int *count = data;
 719
 720        (*count) += q->nr;
 721}
 722
 723static int count_unmerged_entries(void)
 724{
 725        int i, ret = 0;
 726
 727        for (i = 0; i < active_nr; i++)
 728                if (ce_stage(active_cache[i]))
 729                        ret++;
 730
 731        return ret;
 732}
 733
 734static void split_merge_strategies(const char *string, struct strategy **list,
 735                                   int *nr, int *alloc)
 736{
 737        char *p, *q, *buf;
 738
 739        if (!string)
 740                return;
 741
 742        buf = xstrdup(string);
 743        q = buf;
 744        for (;;) {
 745                p = strchr(q, ' ');
 746                if (!p) {
 747                        ALLOC_GROW(*list, *nr + 1, *alloc);
 748                        (*list)[(*nr)++].name = xstrdup(q);
 749                        free(buf);
 750                        return;
 751                } else {
 752                        *p = '\0';
 753                        ALLOC_GROW(*list, *nr + 1, *alloc);
 754                        (*list)[(*nr)++].name = xstrdup(q);
 755                        q = ++p;
 756                }
 757        }
 758}
 759
 760static void add_strategies(const char *string, unsigned attr)
 761{
 762        struct strategy *list = NULL;
 763        int list_alloc = 0, list_nr = 0, i;
 764
 765        memset(&list, 0, sizeof(list));
 766        split_merge_strategies(string, &list, &list_nr, &list_alloc);
 767        if (list) {
 768                for (i = 0; i < list_nr; i++)
 769                        append_strategy(get_strategy(list[i].name));
 770                return;
 771        }
 772        for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 773                if (all_strategy[i].attr & attr)
 774                        append_strategy(&all_strategy[i]);
 775
 776}
 777
 778static void write_merge_msg(struct strbuf *msg)
 779{
 780        const char *filename = git_path("MERGE_MSG");
 781        int fd = open(filename, O_WRONLY | O_CREAT, 0666);
 782        if (fd < 0)
 783                die_errno(_("Could not open '%s' for writing"),
 784                          filename);
 785        if (write_in_full(fd, msg->buf, msg->len) != msg->len)
 786                die_errno(_("Could not write to '%s'"), filename);
 787        close(fd);
 788}
 789
 790static void read_merge_msg(struct strbuf *msg)
 791{
 792        const char *filename = git_path("MERGE_MSG");
 793        strbuf_reset(msg);
 794        if (strbuf_read_file(msg, filename, 0) < 0)
 795                die_errno(_("Could not read from '%s'"), filename);
 796}
 797
 798static void write_merge_state(struct commit_list *);
 799static void abort_commit(struct commit_list *remoteheads, const char *err_msg)
 800{
 801        if (err_msg)
 802                error("%s", err_msg);
 803        fprintf(stderr,
 804                _("Not committing merge; use 'git commit' to complete the merge.\n"));
 805        write_merge_state(remoteheads);
 806        exit(1);
 807}
 808
 809static const char merge_editor_comment[] =
 810N_("Please enter a commit message to explain why this merge is necessary,\n"
 811   "especially if it merges an updated upstream into a topic branch.\n"
 812   "\n"
 813   "Lines starting with '%c' will be ignored, and an empty message aborts\n"
 814   "the commit.\n");
 815
 816static void prepare_to_commit(struct commit_list *remoteheads)
 817{
 818        struct strbuf msg = STRBUF_INIT;
 819        strbuf_addbuf(&msg, &merge_msg);
 820        strbuf_addch(&msg, '\n');
 821        if (0 < option_edit)
 822                strbuf_commented_addf(&msg, _(merge_editor_comment), comment_line_char);
 823        write_merge_msg(&msg);
 824        if (run_hook(get_index_file(), "prepare-commit-msg",
 825                     git_path("MERGE_MSG"), "merge", NULL, NULL))
 826                abort_commit(remoteheads, NULL);
 827        if (0 < option_edit) {
 828                if (launch_editor(git_path("MERGE_MSG"), NULL, NULL))
 829                        abort_commit(remoteheads, NULL);
 830        }
 831        read_merge_msg(&msg);
 832        stripspace(&msg, 0 < option_edit);
 833        if (!msg.len)
 834                abort_commit(remoteheads, _("Empty commit message."));
 835        strbuf_release(&merge_msg);
 836        strbuf_addbuf(&merge_msg, &msg);
 837        strbuf_release(&msg);
 838}
 839
 840static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
 841{
 842        unsigned char result_tree[20], result_commit[20];
 843        struct commit_list *parent = xmalloc(sizeof(*parent));
 844
 845        write_tree_trivial(result_tree);
 846        printf(_("Wonderful.\n"));
 847        parent->item = head;
 848        parent->next = xmalloc(sizeof(*parent->next));
 849        parent->next->item = remoteheads->item;
 850        parent->next->next = NULL;
 851        prepare_to_commit(remoteheads);
 852        if (commit_tree(&merge_msg, result_tree, parent, result_commit, NULL,
 853                        sign_commit))
 854                die(_("failed to write commit object"));
 855        finish(head, remoteheads, result_commit, "In-index merge");
 856        drop_save();
 857        return 0;
 858}
 859
 860static int finish_automerge(struct commit *head,
 861                            int head_subsumed,
 862                            struct commit_list *common,
 863                            struct commit_list *remoteheads,
 864                            unsigned char *result_tree,
 865                            const char *wt_strategy)
 866{
 867        struct commit_list *parents = NULL;
 868        struct strbuf buf = STRBUF_INIT;
 869        unsigned char result_commit[20];
 870
 871        free_commit_list(common);
 872        parents = remoteheads;
 873        if (!head_subsumed || fast_forward == FF_NO)
 874                commit_list_insert(head, &parents);
 875        strbuf_addch(&merge_msg, '\n');
 876        prepare_to_commit(remoteheads);
 877        if (commit_tree(&merge_msg, result_tree, parents, result_commit,
 878                        NULL, sign_commit))
 879                die(_("failed to write commit object"));
 880        strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
 881        finish(head, remoteheads, result_commit, buf.buf);
 882        strbuf_release(&buf);
 883        drop_save();
 884        return 0;
 885}
 886
 887static int suggest_conflicts(int renormalizing)
 888{
 889        const char *filename;
 890        FILE *fp;
 891        int pos;
 892
 893        filename = git_path("MERGE_MSG");
 894        fp = fopen(filename, "a");
 895        if (!fp)
 896                die_errno(_("Could not open '%s' for writing"), filename);
 897        fprintf(fp, "\nConflicts:\n");
 898        for (pos = 0; pos < active_nr; pos++) {
 899                const struct cache_entry *ce = active_cache[pos];
 900
 901                if (ce_stage(ce)) {
 902                        fprintf(fp, "\t%s\n", ce->name);
 903                        while (pos + 1 < active_nr &&
 904                                        !strcmp(ce->name,
 905                                                active_cache[pos + 1]->name))
 906                                pos++;
 907                }
 908        }
 909        fclose(fp);
 910        rerere(allow_rerere_auto);
 911        printf(_("Automatic merge failed; "
 912                        "fix conflicts and then commit the result.\n"));
 913        return 1;
 914}
 915
 916static struct commit *is_old_style_invocation(int argc, const char **argv,
 917                                              const unsigned char *head)
 918{
 919        struct commit *second_token = NULL;
 920        if (argc > 2) {
 921                unsigned char second_sha1[20];
 922
 923                if (get_sha1(argv[1], second_sha1))
 924                        return NULL;
 925                second_token = lookup_commit_reference_gently(second_sha1, 0);
 926                if (!second_token)
 927                        die(_("'%s' is not a commit"), argv[1]);
 928                if (hashcmp(second_token->object.sha1, head))
 929                        return NULL;
 930        }
 931        return second_token;
 932}
 933
 934static int evaluate_result(void)
 935{
 936        int cnt = 0;
 937        struct rev_info rev;
 938
 939        /* Check how many files differ. */
 940        init_revisions(&rev, "");
 941        setup_revisions(0, NULL, &rev, NULL);
 942        rev.diffopt.output_format |=
 943                DIFF_FORMAT_CALLBACK;
 944        rev.diffopt.format_callback = count_diff_files;
 945        rev.diffopt.format_callback_data = &cnt;
 946        run_diff_files(&rev, 0);
 947
 948        /*
 949         * Check how many unmerged entries are
 950         * there.
 951         */
 952        cnt += count_unmerged_entries();
 953
 954        return cnt;
 955}
 956
 957/*
 958 * Pretend as if the user told us to merge with the remote-tracking
 959 * branch we have for the upstream of the current branch
 960 */
 961static int setup_with_upstream(const char ***argv)
 962{
 963        struct branch *branch = branch_get(NULL);
 964        int i;
 965        const char **args;
 966
 967        if (!branch)
 968                die(_("No current branch."));
 969        if (!branch->remote)
 970                die(_("No remote for the current branch."));
 971        if (!branch->merge_nr)
 972                die(_("No default upstream defined for the current branch."));
 973
 974        args = xcalloc(branch->merge_nr + 1, sizeof(char *));
 975        for (i = 0; i < branch->merge_nr; i++) {
 976                if (!branch->merge[i]->dst)
 977                        die(_("No remote-tracking branch for %s from %s"),
 978                            branch->merge[i]->src, branch->remote_name);
 979                args[i] = branch->merge[i]->dst;
 980        }
 981        args[i] = NULL;
 982        *argv = args;
 983        return i;
 984}
 985
 986static void write_merge_state(struct commit_list *remoteheads)
 987{
 988        const char *filename;
 989        int fd;
 990        struct commit_list *j;
 991        struct strbuf buf = STRBUF_INIT;
 992
 993        for (j = remoteheads; j; j = j->next) {
 994                unsigned const char *sha1;
 995                struct commit *c = j->item;
 996                if (c->util && merge_remote_util(c)->obj) {
 997                        sha1 = merge_remote_util(c)->obj->sha1;
 998                } else {
 999                        sha1 = c->object.sha1;
1000                }
1001                strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
1002        }
1003        filename = git_path("MERGE_HEAD");
1004        fd = open(filename, O_WRONLY | O_CREAT, 0666);
1005        if (fd < 0)
1006                die_errno(_("Could not open '%s' for writing"), filename);
1007        if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1008                die_errno(_("Could not write to '%s'"), filename);
1009        close(fd);
1010        strbuf_addch(&merge_msg, '\n');
1011        write_merge_msg(&merge_msg);
1012
1013        filename = git_path("MERGE_MODE");
1014        fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
1015        if (fd < 0)
1016                die_errno(_("Could not open '%s' for writing"), filename);
1017        strbuf_reset(&buf);
1018        if (fast_forward == FF_NO)
1019                strbuf_addf(&buf, "no-ff");
1020        if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1021                die_errno(_("Could not write to '%s'"), filename);
1022        close(fd);
1023}
1024
1025static int default_edit_option(void)
1026{
1027        static const char name[] = "GIT_MERGE_AUTOEDIT";
1028        const char *e = getenv(name);
1029        struct stat st_stdin, st_stdout;
1030
1031        if (have_message)
1032                /* an explicit -m msg without --[no-]edit */
1033                return 0;
1034
1035        if (e) {
1036                int v = git_config_maybe_bool(name, e);
1037                if (v < 0)
1038                        die("Bad value '%s' in environment '%s'", e, name);
1039                return v;
1040        }
1041
1042        /* Use editor if stdin and stdout are the same and is a tty */
1043        return (!fstat(0, &st_stdin) &&
1044                !fstat(1, &st_stdout) &&
1045                isatty(0) && isatty(1) &&
1046                st_stdin.st_dev == st_stdout.st_dev &&
1047                st_stdin.st_ino == st_stdout.st_ino &&
1048                st_stdin.st_mode == st_stdout.st_mode);
1049}
1050
1051static struct commit_list *collect_parents(struct commit *head_commit,
1052                                           int *head_subsumed,
1053                                           int argc, const char **argv)
1054{
1055        int i;
1056        struct commit_list *remoteheads = NULL, *parents, *next;
1057        struct commit_list **remotes = &remoteheads;
1058
1059        if (head_commit)
1060                remotes = &commit_list_insert(head_commit, remotes)->next;
1061        for (i = 0; i < argc; i++) {
1062                struct commit *commit = get_merge_parent(argv[i]);
1063                if (!commit)
1064                        help_unknown_ref(argv[i], "merge",
1065                                         "not something we can merge");
1066                remotes = &commit_list_insert(commit, remotes)->next;
1067        }
1068        *remotes = NULL;
1069
1070        parents = reduce_heads(remoteheads);
1071
1072        *head_subsumed = 1; /* we will flip this to 0 when we find it */
1073        for (remoteheads = NULL, remotes = &remoteheads;
1074             parents;
1075             parents = next) {
1076                struct commit *commit = parents->item;
1077                next = parents->next;
1078                if (commit == head_commit)
1079                        *head_subsumed = 0;
1080                else
1081                        remotes = &commit_list_insert(commit, remotes)->next;
1082        }
1083        return remoteheads;
1084}
1085
1086int cmd_merge(int argc, const char **argv, const char *prefix)
1087{
1088        unsigned char result_tree[20];
1089        unsigned char stash[20];
1090        unsigned char head_sha1[20];
1091        struct commit *head_commit;
1092        struct strbuf buf = STRBUF_INIT;
1093        const char *head_arg;
1094        int flag, i, ret = 0, head_subsumed;
1095        int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
1096        struct commit_list *common = NULL;
1097        const char *best_strategy = NULL, *wt_strategy = NULL;
1098        struct commit_list *remoteheads, *p;
1099        void *branch_to_free;
1100
1101        if (argc == 2 && !strcmp(argv[1], "-h"))
1102                usage_with_options(builtin_merge_usage, builtin_merge_options);
1103
1104        /*
1105         * Check if we are _not_ on a detached HEAD, i.e. if there is a
1106         * current branch.
1107         */
1108        branch = branch_to_free = resolve_refdup("HEAD", head_sha1, 0, &flag);
1109        if (branch && starts_with(branch, "refs/heads/"))
1110                branch += 11;
1111        if (!branch || is_null_sha1(head_sha1))
1112                head_commit = NULL;
1113        else
1114                head_commit = lookup_commit_or_die(head_sha1, "HEAD");
1115
1116        git_config(git_merge_config, NULL);
1117
1118        if (branch_mergeoptions)
1119                parse_branch_merge_options(branch_mergeoptions);
1120        argc = parse_options(argc, argv, prefix, builtin_merge_options,
1121                        builtin_merge_usage, 0);
1122        if (shortlog_len < 0)
1123                shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;
1124
1125        if (verbosity < 0 && show_progress == -1)
1126                show_progress = 0;
1127
1128        if (abort_current_merge) {
1129                int nargc = 2;
1130                const char *nargv[] = {"reset", "--merge", NULL};
1131
1132                if (!file_exists(git_path("MERGE_HEAD")))
1133                        die(_("There is no merge to abort (MERGE_HEAD missing)."));
1134
1135                /* Invoke 'git reset --merge' */
1136                ret = cmd_reset(nargc, nargv, prefix);
1137                goto done;
1138        }
1139
1140        if (read_cache_unmerged())
1141                die_resolve_conflict("merge");
1142
1143        if (file_exists(git_path("MERGE_HEAD"))) {
1144                /*
1145                 * There is no unmerged entry, don't advise 'git
1146                 * add/rm <file>', just 'git commit'.
1147                 */
1148                if (advice_resolve_conflict)
1149                        die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1150                                  "Please, commit your changes before you can merge."));
1151                else
1152                        die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1153        }
1154        if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
1155                if (advice_resolve_conflict)
1156                        die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1157                            "Please, commit your changes before you can merge."));
1158                else
1159                        die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
1160        }
1161        resolve_undo_clear();
1162
1163        if (verbosity < 0)
1164                show_diffstat = 0;
1165
1166        if (squash) {
1167                if (fast_forward == FF_NO)
1168                        die(_("You cannot combine --squash with --no-ff."));
1169                option_commit = 0;
1170        }
1171
1172        if (!abort_current_merge) {
1173                if (!argc) {
1174                        if (default_to_upstream)
1175                                argc = setup_with_upstream(&argv);
1176                        else
1177                                die(_("No commit specified and merge.defaultToUpstream not set."));
1178                } else if (argc == 1 && !strcmp(argv[0], "-"))
1179                        argv[0] = "@{-1}";
1180        }
1181        if (!argc)
1182                usage_with_options(builtin_merge_usage,
1183                        builtin_merge_options);
1184
1185        /*
1186         * This could be traditional "merge <msg> HEAD <commit>..."  and
1187         * the way we can tell it is to see if the second token is HEAD,
1188         * but some people might have misused the interface and used a
1189         * commit-ish that is the same as HEAD there instead.
1190         * Traditional format never would have "-m" so it is an
1191         * additional safety measure to check for it.
1192         */
1193
1194        if (!have_message && head_commit &&
1195            is_old_style_invocation(argc, argv, head_commit->object.sha1)) {
1196                strbuf_addstr(&merge_msg, argv[0]);
1197                head_arg = argv[1];
1198                argv += 2;
1199                argc -= 2;
1200                remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
1201        } else if (!head_commit) {
1202                struct commit *remote_head;
1203                /*
1204                 * If the merged head is a valid one there is no reason
1205                 * to forbid "git merge" into a branch yet to be born.
1206                 * We do the same for "git pull".
1207                 */
1208                if (argc != 1)
1209                        die(_("Can merge only exactly one commit into "
1210                                "empty head"));
1211                if (squash)
1212                        die(_("Squash commit into empty head not supported yet"));
1213                if (fast_forward == FF_NO)
1214                        die(_("Non-fast-forward commit does not make sense into "
1215                            "an empty head"));
1216                remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
1217                remote_head = remoteheads->item;
1218                if (!remote_head)
1219                        die(_("%s - not something we can merge"), argv[0]);
1220                read_empty(remote_head->object.sha1, 0);
1221                update_ref("initial pull", "HEAD", remote_head->object.sha1,
1222                           NULL, 0, DIE_ON_ERR);
1223                goto done;
1224        } else {
1225                struct strbuf merge_names = STRBUF_INIT;
1226
1227                /* We are invoked directly as the first-class UI. */
1228                head_arg = "HEAD";
1229
1230                /*
1231                 * All the rest are the commits being merged; prepare
1232                 * the standard merge summary message to be appended
1233                 * to the given message.
1234                 */
1235                remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
1236                for (p = remoteheads; p; p = p->next)
1237                        merge_name(merge_remote_util(p->item)->name, &merge_names);
1238
1239                if (!have_message || shortlog_len) {
1240                        struct fmt_merge_msg_opts opts;
1241                        memset(&opts, 0, sizeof(opts));
1242                        opts.add_title = !have_message;
1243                        opts.shortlog_len = shortlog_len;
1244                        opts.credit_people = (0 < option_edit);
1245
1246                        fmt_merge_msg(&merge_names, &merge_msg, &opts);
1247                        if (merge_msg.len)
1248                                strbuf_setlen(&merge_msg, merge_msg.len - 1);
1249                }
1250        }
1251
1252        if (!head_commit || !argc)
1253                usage_with_options(builtin_merge_usage,
1254                        builtin_merge_options);
1255
1256        if (verify_signatures) {
1257                for (p = remoteheads; p; p = p->next) {
1258                        struct commit *commit = p->item;
1259                        char hex[41];
1260                        struct signature_check signature_check;
1261                        memset(&signature_check, 0, sizeof(signature_check));
1262
1263                        check_commit_signature(commit, &signature_check);
1264
1265                        strcpy(hex, find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
1266                        switch (signature_check.result) {
1267                        case 'G':
1268                                break;
1269                        case 'U':
1270                                die(_("Commit %s has an untrusted GPG signature, "
1271                                      "allegedly by %s."), hex, signature_check.signer);
1272                        case 'B':
1273                                die(_("Commit %s has a bad GPG signature "
1274                                      "allegedly by %s."), hex, signature_check.signer);
1275                        default: /* 'N' */
1276                                die(_("Commit %s does not have a GPG signature."), hex);
1277                        }
1278                        if (verbosity >= 0 && signature_check.result == 'G')
1279                                printf(_("Commit %s has a good GPG signature by %s\n"),
1280                                       hex, signature_check.signer);
1281
1282                        free(signature_check.gpg_output);
1283                        free(signature_check.gpg_status);
1284                        free(signature_check.signer);
1285                        free(signature_check.key);
1286                }
1287        }
1288
1289        strbuf_addstr(&buf, "merge");
1290        for (p = remoteheads; p; p = p->next)
1291                strbuf_addf(&buf, " %s", merge_remote_util(p->item)->name);
1292        setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1293        strbuf_reset(&buf);
1294
1295        for (p = remoteheads; p; p = p->next) {
1296                struct commit *commit = p->item;
1297                strbuf_addf(&buf, "GITHEAD_%s",
1298                            sha1_to_hex(commit->object.sha1));
1299                setenv(buf.buf, merge_remote_util(commit)->name, 1);
1300                strbuf_reset(&buf);
1301                if (fast_forward != FF_ONLY &&
1302                    merge_remote_util(commit) &&
1303                    merge_remote_util(commit)->obj &&
1304                    merge_remote_util(commit)->obj->type == OBJ_TAG)
1305                        fast_forward = FF_NO;
1306        }
1307
1308        if (option_edit < 0)
1309                option_edit = default_edit_option();
1310
1311        if (!use_strategies) {
1312                if (!remoteheads)
1313                        ; /* already up-to-date */
1314                else if (!remoteheads->next)
1315                        add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1316                else
1317                        add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1318        }
1319
1320        for (i = 0; i < use_strategies_nr; i++) {
1321                if (use_strategies[i]->attr & NO_FAST_FORWARD)
1322                        fast_forward = FF_NO;
1323                if (use_strategies[i]->attr & NO_TRIVIAL)
1324                        allow_trivial = 0;
1325        }
1326
1327        if (!remoteheads)
1328                ; /* already up-to-date */
1329        else if (!remoteheads->next)
1330                common = get_merge_bases(head_commit, remoteheads->item, 1);
1331        else {
1332                struct commit_list *list = remoteheads;
1333                commit_list_insert(head_commit, &list);
1334                common = get_octopus_merge_bases(list);
1335                free(list);
1336        }
1337
1338        update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.sha1,
1339                   NULL, 0, DIE_ON_ERR);
1340
1341        if (remoteheads && !common)
1342                ; /* No common ancestors found. We need a real merge. */
1343        else if (!remoteheads ||
1344                 (!remoteheads->next && !common->next &&
1345                  common->item == remoteheads->item)) {
1346                /*
1347                 * If head can reach all the merge then we are up to date.
1348                 * but first the most common case of merging one remote.
1349                 */
1350                finish_up_to_date("Already up-to-date.");
1351                goto done;
1352        } else if (fast_forward != FF_NO && !remoteheads->next &&
1353                        !common->next &&
1354                        !hashcmp(common->item->object.sha1, head_commit->object.sha1)) {
1355                /* Again the most common case of merging one remote. */
1356                struct strbuf msg = STRBUF_INIT;
1357                struct commit *commit;
1358                char hex[41];
1359
1360                strcpy(hex, find_unique_abbrev(head_commit->object.sha1, DEFAULT_ABBREV));
1361
1362                if (verbosity >= 0)
1363                        printf(_("Updating %s..%s\n"),
1364                                hex,
1365                                find_unique_abbrev(remoteheads->item->object.sha1,
1366                                DEFAULT_ABBREV));
1367                strbuf_addstr(&msg, "Fast-forward");
1368                if (have_message)
1369                        strbuf_addstr(&msg,
1370                                " (no commit created; -m option ignored)");
1371                commit = remoteheads->item;
1372                if (!commit) {
1373                        ret = 1;
1374                        goto done;
1375                }
1376
1377                if (checkout_fast_forward(head_commit->object.sha1,
1378                                          commit->object.sha1,
1379                                          overwrite_ignore)) {
1380                        ret = 1;
1381                        goto done;
1382                }
1383
1384                finish(head_commit, remoteheads, commit->object.sha1, msg.buf);
1385                drop_save();
1386                goto done;
1387        } else if (!remoteheads->next && common->next)
1388                ;
1389                /*
1390                 * We are not doing octopus and not fast-forward.  Need
1391                 * a real merge.
1392                 */
1393        else if (!remoteheads->next && !common->next && option_commit) {
1394                /*
1395                 * We are not doing octopus, not fast-forward, and have
1396                 * only one common.
1397                 */
1398                refresh_cache(REFRESH_QUIET);
1399                if (allow_trivial && fast_forward != FF_ONLY) {
1400                        /* See if it is really trivial. */
1401                        git_committer_info(IDENT_STRICT);
1402                        printf(_("Trying really trivial in-index merge...\n"));
1403                        if (!read_tree_trivial(common->item->object.sha1,
1404                                               head_commit->object.sha1,
1405                                               remoteheads->item->object.sha1)) {
1406                                ret = merge_trivial(head_commit, remoteheads);
1407                                goto done;
1408                        }
1409                        printf(_("Nope.\n"));
1410                }
1411        } else {
1412                /*
1413                 * An octopus.  If we can reach all the remote we are up
1414                 * to date.
1415                 */
1416                int up_to_date = 1;
1417                struct commit_list *j;
1418
1419                for (j = remoteheads; j; j = j->next) {
1420                        struct commit_list *common_one;
1421
1422                        /*
1423                         * Here we *have* to calculate the individual
1424                         * merge_bases again, otherwise "git merge HEAD^
1425                         * HEAD^^" would be missed.
1426                         */
1427                        common_one = get_merge_bases(head_commit, j->item, 1);
1428                        if (hashcmp(common_one->item->object.sha1,
1429                                j->item->object.sha1)) {
1430                                up_to_date = 0;
1431                                break;
1432                        }
1433                }
1434                if (up_to_date) {
1435                        finish_up_to_date("Already up-to-date. Yeeah!");
1436                        goto done;
1437                }
1438        }
1439
1440        if (fast_forward == FF_ONLY)
1441                die(_("Not possible to fast-forward, aborting."));
1442
1443        /* We are going to make a new commit. */
1444        git_committer_info(IDENT_STRICT);
1445
1446        /*
1447         * At this point, we need a real merge.  No matter what strategy
1448         * we use, it would operate on the index, possibly affecting the
1449         * working tree, and when resolved cleanly, have the desired
1450         * tree in the index -- this means that the index must be in
1451         * sync with the head commit.  The strategies are responsible
1452         * to ensure this.
1453         */
1454        if (use_strategies_nr == 1 ||
1455            /*
1456             * Stash away the local changes so that we can try more than one.
1457             */
1458            save_state(stash))
1459                hashcpy(stash, null_sha1);
1460
1461        for (i = 0; i < use_strategies_nr; i++) {
1462                int ret;
1463                if (i) {
1464                        printf(_("Rewinding the tree to pristine...\n"));
1465                        restore_state(head_commit->object.sha1, stash);
1466                }
1467                if (use_strategies_nr != 1)
1468                        printf(_("Trying merge strategy %s...\n"),
1469                                use_strategies[i]->name);
1470                /*
1471                 * Remember which strategy left the state in the working
1472                 * tree.
1473                 */
1474                wt_strategy = use_strategies[i]->name;
1475
1476                ret = try_merge_strategy(use_strategies[i]->name,
1477                                         common, remoteheads,
1478                                         head_commit, head_arg);
1479                if (!option_commit && !ret) {
1480                        merge_was_ok = 1;
1481                        /*
1482                         * This is necessary here just to avoid writing
1483                         * the tree, but later we will *not* exit with
1484                         * status code 1 because merge_was_ok is set.
1485                         */
1486                        ret = 1;
1487                }
1488
1489                if (ret) {
1490                        /*
1491                         * The backend exits with 1 when conflicts are
1492                         * left to be resolved, with 2 when it does not
1493                         * handle the given merge at all.
1494                         */
1495                        if (ret == 1) {
1496                                int cnt = evaluate_result();
1497
1498                                if (best_cnt <= 0 || cnt <= best_cnt) {
1499                                        best_strategy = use_strategies[i]->name;
1500                                        best_cnt = cnt;
1501                                }
1502                        }
1503                        if (merge_was_ok)
1504                                break;
1505                        else
1506                                continue;
1507                }
1508
1509                /* Automerge succeeded. */
1510                write_tree_trivial(result_tree);
1511                automerge_was_ok = 1;
1512                break;
1513        }
1514
1515        /*
1516         * If we have a resulting tree, that means the strategy module
1517         * auto resolved the merge cleanly.
1518         */
1519        if (automerge_was_ok) {
1520                ret = finish_automerge(head_commit, head_subsumed,
1521                                       common, remoteheads,
1522                                       result_tree, wt_strategy);
1523                goto done;
1524        }
1525
1526        /*
1527         * Pick the result from the best strategy and have the user fix
1528         * it up.
1529         */
1530        if (!best_strategy) {
1531                restore_state(head_commit->object.sha1, stash);
1532                if (use_strategies_nr > 1)
1533                        fprintf(stderr,
1534                                _("No merge strategy handled the merge.\n"));
1535                else
1536                        fprintf(stderr, _("Merge with strategy %s failed.\n"),
1537                                use_strategies[0]->name);
1538                ret = 2;
1539                goto done;
1540        } else if (best_strategy == wt_strategy)
1541                ; /* We already have its result in the working tree. */
1542        else {
1543                printf(_("Rewinding the tree to pristine...\n"));
1544                restore_state(head_commit->object.sha1, stash);
1545                printf(_("Using the %s to prepare resolving by hand.\n"),
1546                        best_strategy);
1547                try_merge_strategy(best_strategy, common, remoteheads,
1548                                   head_commit, head_arg);
1549        }
1550
1551        if (squash)
1552                finish(head_commit, remoteheads, NULL, NULL);
1553        else
1554                write_merge_state(remoteheads);
1555
1556        if (merge_was_ok)
1557                fprintf(stderr, _("Automatic merge went well; "
1558                        "stopped before committing as requested\n"));
1559        else
1560                ret = suggest_conflicts(option_renormalize);
1561
1562done:
1563        free(branch_to_free);
1564        return ret;
1565}