builtin / merge.con commit update-ref.c: extract a new function, parse_next_sha1() (3afcc46)
   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                                UPDATE_REFS_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_le(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        } else if (!strcmp(k, "commit.gpgsign")) {
 601                sign_commit = git_config_bool(k, v) ? "" : NULL;
 602                return 0;
 603        }
 604
 605        status = fmt_merge_msg_config(k, v, cb);
 606        if (status)
 607                return status;
 608        status = git_gpg_config(k, v, NULL);
 609        if (status)
 610                return status;
 611        return git_diff_ui_config(k, v, cb);
 612}
 613
 614static int read_tree_trivial(unsigned char *common, unsigned char *head,
 615                             unsigned char *one)
 616{
 617        int i, nr_trees = 0;
 618        struct tree *trees[MAX_UNPACK_TREES];
 619        struct tree_desc t[MAX_UNPACK_TREES];
 620        struct unpack_trees_options opts;
 621
 622        memset(&opts, 0, sizeof(opts));
 623        opts.head_idx = 2;
 624        opts.src_index = &the_index;
 625        opts.dst_index = &the_index;
 626        opts.update = 1;
 627        opts.verbose_update = 1;
 628        opts.trivial_merges_only = 1;
 629        opts.merge = 1;
 630        trees[nr_trees] = parse_tree_indirect(common);
 631        if (!trees[nr_trees++])
 632                return -1;
 633        trees[nr_trees] = parse_tree_indirect(head);
 634        if (!trees[nr_trees++])
 635                return -1;
 636        trees[nr_trees] = parse_tree_indirect(one);
 637        if (!trees[nr_trees++])
 638                return -1;
 639        opts.fn = threeway_merge;
 640        cache_tree_free(&active_cache_tree);
 641        for (i = 0; i < nr_trees; i++) {
 642                parse_tree(trees[i]);
 643                init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 644        }
 645        if (unpack_trees(nr_trees, t, &opts))
 646                return -1;
 647        return 0;
 648}
 649
 650static void write_tree_trivial(unsigned char *sha1)
 651{
 652        if (write_cache_as_tree(sha1, 0, NULL))
 653                die(_("git write-tree failed to write a tree"));
 654}
 655
 656static int try_merge_strategy(const char *strategy, struct commit_list *common,
 657                              struct commit_list *remoteheads,
 658                              struct commit *head, const char *head_arg)
 659{
 660        int index_fd;
 661        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 662
 663        index_fd = hold_locked_index(lock, 1);
 664        refresh_cache(REFRESH_QUIET);
 665        if (active_cache_changed &&
 666                        (write_cache(index_fd, active_cache, active_nr) ||
 667                         commit_locked_index(lock)))
 668                return error(_("Unable to write index."));
 669        rollback_lock_file(lock);
 670
 671        if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
 672                int clean, x;
 673                struct commit *result;
 674                struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 675                int index_fd;
 676                struct commit_list *reversed = NULL;
 677                struct merge_options o;
 678                struct commit_list *j;
 679
 680                if (remoteheads->next) {
 681                        error(_("Not handling anything other than two heads merge."));
 682                        return 2;
 683                }
 684
 685                init_merge_options(&o);
 686                if (!strcmp(strategy, "subtree"))
 687                        o.subtree_shift = "";
 688
 689                o.renormalize = option_renormalize;
 690                o.show_rename_progress =
 691                        show_progress == -1 ? isatty(2) : show_progress;
 692
 693                for (x = 0; x < xopts_nr; x++)
 694                        if (parse_merge_opt(&o, xopts[x]))
 695                                die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
 696
 697                o.branch1 = head_arg;
 698                o.branch2 = merge_remote_util(remoteheads->item)->name;
 699
 700                for (j = common; j; j = j->next)
 701                        commit_list_insert(j->item, &reversed);
 702
 703                index_fd = hold_locked_index(lock, 1);
 704                clean = merge_recursive(&o, head,
 705                                remoteheads->item, reversed, &result);
 706                if (active_cache_changed &&
 707                                (write_cache(index_fd, active_cache, active_nr) ||
 708                                 commit_locked_index(lock)))
 709                        die (_("unable to write %s"), get_index_file());
 710                rollback_lock_file(lock);
 711                return clean ? 0 : 1;
 712        } else {
 713                return try_merge_command(strategy, xopts_nr, xopts,
 714                                                common, head_arg, remoteheads);
 715        }
 716}
 717
 718static void count_diff_files(struct diff_queue_struct *q,
 719                             struct diff_options *opt, void *data)
 720{
 721        int *count = data;
 722
 723        (*count) += q->nr;
 724}
 725
 726static int count_unmerged_entries(void)
 727{
 728        int i, ret = 0;
 729
 730        for (i = 0; i < active_nr; i++)
 731                if (ce_stage(active_cache[i]))
 732                        ret++;
 733
 734        return ret;
 735}
 736
 737static void split_merge_strategies(const char *string, struct strategy **list,
 738                                   int *nr, int *alloc)
 739{
 740        char *p, *q, *buf;
 741
 742        if (!string)
 743                return;
 744
 745        buf = xstrdup(string);
 746        q = buf;
 747        for (;;) {
 748                p = strchr(q, ' ');
 749                if (!p) {
 750                        ALLOC_GROW(*list, *nr + 1, *alloc);
 751                        (*list)[(*nr)++].name = xstrdup(q);
 752                        free(buf);
 753                        return;
 754                } else {
 755                        *p = '\0';
 756                        ALLOC_GROW(*list, *nr + 1, *alloc);
 757                        (*list)[(*nr)++].name = xstrdup(q);
 758                        q = ++p;
 759                }
 760        }
 761}
 762
 763static void add_strategies(const char *string, unsigned attr)
 764{
 765        struct strategy *list = NULL;
 766        int list_alloc = 0, list_nr = 0, i;
 767
 768        memset(&list, 0, sizeof(list));
 769        split_merge_strategies(string, &list, &list_nr, &list_alloc);
 770        if (list) {
 771                for (i = 0; i < list_nr; i++)
 772                        append_strategy(get_strategy(list[i].name));
 773                return;
 774        }
 775        for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 776                if (all_strategy[i].attr & attr)
 777                        append_strategy(&all_strategy[i]);
 778
 779}
 780
 781static void write_merge_msg(struct strbuf *msg)
 782{
 783        const char *filename = git_path("MERGE_MSG");
 784        int fd = open(filename, O_WRONLY | O_CREAT, 0666);
 785        if (fd < 0)
 786                die_errno(_("Could not open '%s' for writing"),
 787                          filename);
 788        if (write_in_full(fd, msg->buf, msg->len) != msg->len)
 789                die_errno(_("Could not write to '%s'"), filename);
 790        close(fd);
 791}
 792
 793static void read_merge_msg(struct strbuf *msg)
 794{
 795        const char *filename = git_path("MERGE_MSG");
 796        strbuf_reset(msg);
 797        if (strbuf_read_file(msg, filename, 0) < 0)
 798                die_errno(_("Could not read from '%s'"), filename);
 799}
 800
 801static void write_merge_state(struct commit_list *);
 802static void abort_commit(struct commit_list *remoteheads, const char *err_msg)
 803{
 804        if (err_msg)
 805                error("%s", err_msg);
 806        fprintf(stderr,
 807                _("Not committing merge; use 'git commit' to complete the merge.\n"));
 808        write_merge_state(remoteheads);
 809        exit(1);
 810}
 811
 812static const char merge_editor_comment[] =
 813N_("Please enter a commit message to explain why this merge is necessary,\n"
 814   "especially if it merges an updated upstream into a topic branch.\n"
 815   "\n"
 816   "Lines starting with '%c' will be ignored, and an empty message aborts\n"
 817   "the commit.\n");
 818
 819static void prepare_to_commit(struct commit_list *remoteheads)
 820{
 821        struct strbuf msg = STRBUF_INIT;
 822        strbuf_addbuf(&msg, &merge_msg);
 823        strbuf_addch(&msg, '\n');
 824        if (0 < option_edit)
 825                strbuf_commented_addf(&msg, _(merge_editor_comment), comment_line_char);
 826        write_merge_msg(&msg);
 827        if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
 828                            git_path("MERGE_MSG"), "merge", NULL))
 829                abort_commit(remoteheads, NULL);
 830        if (0 < option_edit) {
 831                if (launch_editor(git_path("MERGE_MSG"), NULL, NULL))
 832                        abort_commit(remoteheads, NULL);
 833        }
 834        read_merge_msg(&msg);
 835        stripspace(&msg, 0 < option_edit);
 836        if (!msg.len)
 837                abort_commit(remoteheads, _("Empty commit message."));
 838        strbuf_release(&merge_msg);
 839        strbuf_addbuf(&merge_msg, &msg);
 840        strbuf_release(&msg);
 841}
 842
 843static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
 844{
 845        unsigned char result_tree[20], result_commit[20];
 846        struct commit_list *parent = xmalloc(sizeof(*parent));
 847
 848        write_tree_trivial(result_tree);
 849        printf(_("Wonderful.\n"));
 850        parent->item = head;
 851        parent->next = xmalloc(sizeof(*parent->next));
 852        parent->next->item = remoteheads->item;
 853        parent->next->next = NULL;
 854        prepare_to_commit(remoteheads);
 855        if (commit_tree(&merge_msg, result_tree, parent, result_commit, NULL,
 856                        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                            unsigned char *result_tree,
 868                            const char *wt_strategy)
 869{
 870        struct commit_list *parents = NULL;
 871        struct strbuf buf = STRBUF_INIT;
 872        unsigned char result_commit[20];
 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, result_tree, parents, result_commit,
 881                        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(int renormalizing)
 891{
 892        const char *filename;
 893        FILE *fp;
 894        int pos;
 895
 896        filename = git_path("MERGE_MSG");
 897        fp = fopen(filename, "a");
 898        if (!fp)
 899                die_errno(_("Could not open '%s' for writing"), filename);
 900        fprintf(fp, "\nConflicts:\n");
 901        for (pos = 0; pos < active_nr; pos++) {
 902                const struct cache_entry *ce = active_cache[pos];
 903
 904                if (ce_stage(ce)) {
 905                        fprintf(fp, "\t%s\n", ce->name);
 906                        while (pos + 1 < active_nr &&
 907                                        !strcmp(ce->name,
 908                                                active_cache[pos + 1]->name))
 909                                pos++;
 910                }
 911        }
 912        fclose(fp);
 913        rerere(allow_rerere_auto);
 914        printf(_("Automatic merge failed; "
 915                        "fix conflicts and then commit the result.\n"));
 916        return 1;
 917}
 918
 919static struct commit *is_old_style_invocation(int argc, const char **argv,
 920                                              const unsigned char *head)
 921{
 922        struct commit *second_token = NULL;
 923        if (argc > 2) {
 924                unsigned char second_sha1[20];
 925
 926                if (get_sha1(argv[1], second_sha1))
 927                        return NULL;
 928                second_token = lookup_commit_reference_gently(second_sha1, 0);
 929                if (!second_token)
 930                        die(_("'%s' is not a commit"), argv[1]);
 931                if (hashcmp(second_token->object.sha1, head))
 932                        return NULL;
 933        }
 934        return second_token;
 935}
 936
 937static int evaluate_result(void)
 938{
 939        int cnt = 0;
 940        struct rev_info rev;
 941
 942        /* Check how many files differ. */
 943        init_revisions(&rev, "");
 944        setup_revisions(0, NULL, &rev, NULL);
 945        rev.diffopt.output_format |=
 946                DIFF_FORMAT_CALLBACK;
 947        rev.diffopt.format_callback = count_diff_files;
 948        rev.diffopt.format_callback_data = &cnt;
 949        run_diff_files(&rev, 0);
 950
 951        /*
 952         * Check how many unmerged entries are
 953         * there.
 954         */
 955        cnt += count_unmerged_entries();
 956
 957        return cnt;
 958}
 959
 960/*
 961 * Pretend as if the user told us to merge with the remote-tracking
 962 * branch we have for the upstream of the current branch
 963 */
 964static int setup_with_upstream(const char ***argv)
 965{
 966        struct branch *branch = branch_get(NULL);
 967        int i;
 968        const char **args;
 969
 970        if (!branch)
 971                die(_("No current branch."));
 972        if (!branch->remote)
 973                die(_("No remote for the current branch."));
 974        if (!branch->merge_nr)
 975                die(_("No default upstream defined for the current branch."));
 976
 977        args = xcalloc(branch->merge_nr + 1, sizeof(char *));
 978        for (i = 0; i < branch->merge_nr; i++) {
 979                if (!branch->merge[i]->dst)
 980                        die(_("No remote-tracking branch for %s from %s"),
 981                            branch->merge[i]->src, branch->remote_name);
 982                args[i] = branch->merge[i]->dst;
 983        }
 984        args[i] = NULL;
 985        *argv = args;
 986        return i;
 987}
 988
 989static void write_merge_state(struct commit_list *remoteheads)
 990{
 991        const char *filename;
 992        int fd;
 993        struct commit_list *j;
 994        struct strbuf buf = STRBUF_INIT;
 995
 996        for (j = remoteheads; j; j = j->next) {
 997                unsigned const char *sha1;
 998                struct commit *c = j->item;
 999                if (c->util && merge_remote_util(c)->obj) {
1000                        sha1 = merge_remote_util(c)->obj->sha1;
1001                } else {
1002                        sha1 = c->object.sha1;
1003                }
1004                strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
1005        }
1006        filename = git_path("MERGE_HEAD");
1007        fd = open(filename, O_WRONLY | O_CREAT, 0666);
1008        if (fd < 0)
1009                die_errno(_("Could not open '%s' for writing"), filename);
1010        if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1011                die_errno(_("Could not write to '%s'"), filename);
1012        close(fd);
1013        strbuf_addch(&merge_msg, '\n');
1014        write_merge_msg(&merge_msg);
1015
1016        filename = git_path("MERGE_MODE");
1017        fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
1018        if (fd < 0)
1019                die_errno(_("Could not open '%s' for writing"), filename);
1020        strbuf_reset(&buf);
1021        if (fast_forward == FF_NO)
1022                strbuf_addf(&buf, "no-ff");
1023        if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1024                die_errno(_("Could not write to '%s'"), filename);
1025        close(fd);
1026}
1027
1028static int default_edit_option(void)
1029{
1030        static const char name[] = "GIT_MERGE_AUTOEDIT";
1031        const char *e = getenv(name);
1032        struct stat st_stdin, st_stdout;
1033
1034        if (have_message)
1035                /* an explicit -m msg without --[no-]edit */
1036                return 0;
1037
1038        if (e) {
1039                int v = git_config_maybe_bool(name, e);
1040                if (v < 0)
1041                        die("Bad value '%s' in environment '%s'", e, name);
1042                return v;
1043        }
1044
1045        /* Use editor if stdin and stdout are the same and is a tty */
1046        return (!fstat(0, &st_stdin) &&
1047                !fstat(1, &st_stdout) &&
1048                isatty(0) && isatty(1) &&
1049                st_stdin.st_dev == st_stdout.st_dev &&
1050                st_stdin.st_ino == st_stdout.st_ino &&
1051                st_stdin.st_mode == st_stdout.st_mode);
1052}
1053
1054static struct commit_list *collect_parents(struct commit *head_commit,
1055                                           int *head_subsumed,
1056                                           int argc, const char **argv)
1057{
1058        int i;
1059        struct commit_list *remoteheads = NULL, *parents, *next;
1060        struct commit_list **remotes = &remoteheads;
1061
1062        if (head_commit)
1063                remotes = &commit_list_insert(head_commit, remotes)->next;
1064        for (i = 0; i < argc; i++) {
1065                struct commit *commit = get_merge_parent(argv[i]);
1066                if (!commit)
1067                        help_unknown_ref(argv[i], "merge",
1068                                         "not something we can merge");
1069                remotes = &commit_list_insert(commit, remotes)->next;
1070        }
1071        *remotes = NULL;
1072
1073        parents = reduce_heads(remoteheads);
1074
1075        *head_subsumed = 1; /* we will flip this to 0 when we find it */
1076        for (remoteheads = NULL, remotes = &remoteheads;
1077             parents;
1078             parents = next) {
1079                struct commit *commit = parents->item;
1080                next = parents->next;
1081                if (commit == head_commit)
1082                        *head_subsumed = 0;
1083                else
1084                        remotes = &commit_list_insert(commit, remotes)->next;
1085        }
1086        return remoteheads;
1087}
1088
1089int cmd_merge(int argc, const char **argv, const char *prefix)
1090{
1091        unsigned char result_tree[20];
1092        unsigned char stash[20];
1093        unsigned char head_sha1[20];
1094        struct commit *head_commit;
1095        struct strbuf buf = STRBUF_INIT;
1096        const char *head_arg;
1097        int flag, i, ret = 0, head_subsumed;
1098        int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
1099        struct commit_list *common = NULL;
1100        const char *best_strategy = NULL, *wt_strategy = NULL;
1101        struct commit_list *remoteheads, *p;
1102        void *branch_to_free;
1103
1104        if (argc == 2 && !strcmp(argv[1], "-h"))
1105                usage_with_options(builtin_merge_usage, builtin_merge_options);
1106
1107        /*
1108         * Check if we are _not_ on a detached HEAD, i.e. if there is a
1109         * current branch.
1110         */
1111        branch = branch_to_free = resolve_refdup("HEAD", head_sha1, 0, &flag);
1112        if (branch && starts_with(branch, "refs/heads/"))
1113                branch += 11;
1114        if (!branch || is_null_sha1(head_sha1))
1115                head_commit = NULL;
1116        else
1117                head_commit = lookup_commit_or_die(head_sha1, "HEAD");
1118
1119        git_config(git_merge_config, NULL);
1120
1121        if (branch_mergeoptions)
1122                parse_branch_merge_options(branch_mergeoptions);
1123        argc = parse_options(argc, argv, prefix, builtin_merge_options,
1124                        builtin_merge_usage, 0);
1125        if (shortlog_len < 0)
1126                shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;
1127
1128        if (verbosity < 0 && show_progress == -1)
1129                show_progress = 0;
1130
1131        if (abort_current_merge) {
1132                int nargc = 2;
1133                const char *nargv[] = {"reset", "--merge", NULL};
1134
1135                if (!file_exists(git_path("MERGE_HEAD")))
1136                        die(_("There is no merge to abort (MERGE_HEAD missing)."));
1137
1138                /* Invoke 'git reset --merge' */
1139                ret = cmd_reset(nargc, nargv, prefix);
1140                goto done;
1141        }
1142
1143        if (read_cache_unmerged())
1144                die_resolve_conflict("merge");
1145
1146        if (file_exists(git_path("MERGE_HEAD"))) {
1147                /*
1148                 * There is no unmerged entry, don't advise 'git
1149                 * add/rm <file>', just 'git commit'.
1150                 */
1151                if (advice_resolve_conflict)
1152                        die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1153                                  "Please, commit your changes before you can merge."));
1154                else
1155                        die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1156        }
1157        if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
1158                if (advice_resolve_conflict)
1159                        die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1160                            "Please, commit your changes before you can merge."));
1161                else
1162                        die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
1163        }
1164        resolve_undo_clear();
1165
1166        if (verbosity < 0)
1167                show_diffstat = 0;
1168
1169        if (squash) {
1170                if (fast_forward == FF_NO)
1171                        die(_("You cannot combine --squash with --no-ff."));
1172                option_commit = 0;
1173        }
1174
1175        if (!abort_current_merge) {
1176                if (!argc) {
1177                        if (default_to_upstream)
1178                                argc = setup_with_upstream(&argv);
1179                        else
1180                                die(_("No commit specified and merge.defaultToUpstream not set."));
1181                } else if (argc == 1 && !strcmp(argv[0], "-"))
1182                        argv[0] = "@{-1}";
1183        }
1184        if (!argc)
1185                usage_with_options(builtin_merge_usage,
1186                        builtin_merge_options);
1187
1188        /*
1189         * This could be traditional "merge <msg> HEAD <commit>..."  and
1190         * the way we can tell it is to see if the second token is HEAD,
1191         * but some people might have misused the interface and used a
1192         * commit-ish that is the same as HEAD there instead.
1193         * Traditional format never would have "-m" so it is an
1194         * additional safety measure to check for it.
1195         */
1196
1197        if (!have_message && head_commit &&
1198            is_old_style_invocation(argc, argv, head_commit->object.sha1)) {
1199                strbuf_addstr(&merge_msg, argv[0]);
1200                head_arg = argv[1];
1201                argv += 2;
1202                argc -= 2;
1203                remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
1204        } else if (!head_commit) {
1205                struct commit *remote_head;
1206                /*
1207                 * If the merged head is a valid one there is no reason
1208                 * to forbid "git merge" into a branch yet to be born.
1209                 * We do the same for "git pull".
1210                 */
1211                if (argc != 1)
1212                        die(_("Can merge only exactly one commit into "
1213                                "empty head"));
1214                if (squash)
1215                        die(_("Squash commit into empty head not supported yet"));
1216                if (fast_forward == FF_NO)
1217                        die(_("Non-fast-forward commit does not make sense into "
1218                            "an empty head"));
1219                remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
1220                remote_head = remoteheads->item;
1221                if (!remote_head)
1222                        die(_("%s - not something we can merge"), argv[0]);
1223                read_empty(remote_head->object.sha1, 0);
1224                update_ref("initial pull", "HEAD", remote_head->object.sha1,
1225                           NULL, 0, UPDATE_REFS_DIE_ON_ERR);
1226                goto done;
1227        } else {
1228                struct strbuf merge_names = STRBUF_INIT;
1229
1230                /* We are invoked directly as the first-class UI. */
1231                head_arg = "HEAD";
1232
1233                /*
1234                 * All the rest are the commits being merged; prepare
1235                 * the standard merge summary message to be appended
1236                 * to the given message.
1237                 */
1238                remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
1239                for (p = remoteheads; p; p = p->next)
1240                        merge_name(merge_remote_util(p->item)->name, &merge_names);
1241
1242                if (!have_message || shortlog_len) {
1243                        struct fmt_merge_msg_opts opts;
1244                        memset(&opts, 0, sizeof(opts));
1245                        opts.add_title = !have_message;
1246                        opts.shortlog_len = shortlog_len;
1247                        opts.credit_people = (0 < option_edit);
1248
1249                        fmt_merge_msg(&merge_names, &merge_msg, &opts);
1250                        if (merge_msg.len)
1251                                strbuf_setlen(&merge_msg, merge_msg.len - 1);
1252                }
1253        }
1254
1255        if (!head_commit || !argc)
1256                usage_with_options(builtin_merge_usage,
1257                        builtin_merge_options);
1258
1259        if (verify_signatures) {
1260                for (p = remoteheads; p; p = p->next) {
1261                        struct commit *commit = p->item;
1262                        char hex[41];
1263                        struct signature_check signature_check;
1264                        memset(&signature_check, 0, sizeof(signature_check));
1265
1266                        check_commit_signature(commit, &signature_check);
1267
1268                        strcpy(hex, find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
1269                        switch (signature_check.result) {
1270                        case 'G':
1271                                break;
1272                        case 'U':
1273                                die(_("Commit %s has an untrusted GPG signature, "
1274                                      "allegedly by %s."), hex, signature_check.signer);
1275                        case 'B':
1276                                die(_("Commit %s has a bad GPG signature "
1277                                      "allegedly by %s."), hex, signature_check.signer);
1278                        default: /* 'N' */
1279                                die(_("Commit %s does not have a GPG signature."), hex);
1280                        }
1281                        if (verbosity >= 0 && signature_check.result == 'G')
1282                                printf(_("Commit %s has a good GPG signature by %s\n"),
1283                                       hex, signature_check.signer);
1284
1285                        free(signature_check.gpg_output);
1286                        free(signature_check.gpg_status);
1287                        free(signature_check.signer);
1288                        free(signature_check.key);
1289                }
1290        }
1291
1292        strbuf_addstr(&buf, "merge");
1293        for (p = remoteheads; p; p = p->next)
1294                strbuf_addf(&buf, " %s", merge_remote_util(p->item)->name);
1295        setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1296        strbuf_reset(&buf);
1297
1298        for (p = remoteheads; p; p = p->next) {
1299                struct commit *commit = p->item;
1300                strbuf_addf(&buf, "GITHEAD_%s",
1301                            sha1_to_hex(commit->object.sha1));
1302                setenv(buf.buf, merge_remote_util(commit)->name, 1);
1303                strbuf_reset(&buf);
1304                if (fast_forward != FF_ONLY &&
1305                    merge_remote_util(commit) &&
1306                    merge_remote_util(commit)->obj &&
1307                    merge_remote_util(commit)->obj->type == OBJ_TAG)
1308                        fast_forward = FF_NO;
1309        }
1310
1311        if (option_edit < 0)
1312                option_edit = default_edit_option();
1313
1314        if (!use_strategies) {
1315                if (!remoteheads)
1316                        ; /* already up-to-date */
1317                else if (!remoteheads->next)
1318                        add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1319                else
1320                        add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1321        }
1322
1323        for (i = 0; i < use_strategies_nr; i++) {
1324                if (use_strategies[i]->attr & NO_FAST_FORWARD)
1325                        fast_forward = FF_NO;
1326                if (use_strategies[i]->attr & NO_TRIVIAL)
1327                        allow_trivial = 0;
1328        }
1329
1330        if (!remoteheads)
1331                ; /* already up-to-date */
1332        else if (!remoteheads->next)
1333                common = get_merge_bases(head_commit, remoteheads->item, 1);
1334        else {
1335                struct commit_list *list = remoteheads;
1336                commit_list_insert(head_commit, &list);
1337                common = get_octopus_merge_bases(list);
1338                free(list);
1339        }
1340
1341        update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.sha1,
1342                   NULL, 0, UPDATE_REFS_DIE_ON_ERR);
1343
1344        if (remoteheads && !common)
1345                ; /* No common ancestors found. We need a real merge. */
1346        else if (!remoteheads ||
1347                 (!remoteheads->next && !common->next &&
1348                  common->item == remoteheads->item)) {
1349                /*
1350                 * If head can reach all the merge then we are up to date.
1351                 * but first the most common case of merging one remote.
1352                 */
1353                finish_up_to_date("Already up-to-date.");
1354                goto done;
1355        } else if (fast_forward != FF_NO && !remoteheads->next &&
1356                        !common->next &&
1357                        !hashcmp(common->item->object.sha1, head_commit->object.sha1)) {
1358                /* Again the most common case of merging one remote. */
1359                struct strbuf msg = STRBUF_INIT;
1360                struct commit *commit;
1361                char hex[41];
1362
1363                strcpy(hex, find_unique_abbrev(head_commit->object.sha1, DEFAULT_ABBREV));
1364
1365                if (verbosity >= 0)
1366                        printf(_("Updating %s..%s\n"),
1367                                hex,
1368                                find_unique_abbrev(remoteheads->item->object.sha1,
1369                                DEFAULT_ABBREV));
1370                strbuf_addstr(&msg, "Fast-forward");
1371                if (have_message)
1372                        strbuf_addstr(&msg,
1373                                " (no commit created; -m option ignored)");
1374                commit = remoteheads->item;
1375                if (!commit) {
1376                        ret = 1;
1377                        goto done;
1378                }
1379
1380                if (checkout_fast_forward(head_commit->object.sha1,
1381                                          commit->object.sha1,
1382                                          overwrite_ignore)) {
1383                        ret = 1;
1384                        goto done;
1385                }
1386
1387                finish(head_commit, remoteheads, commit->object.sha1, msg.buf);
1388                drop_save();
1389                goto done;
1390        } else if (!remoteheads->next && common->next)
1391                ;
1392                /*
1393                 * We are not doing octopus and not fast-forward.  Need
1394                 * a real merge.
1395                 */
1396        else if (!remoteheads->next && !common->next && option_commit) {
1397                /*
1398                 * We are not doing octopus, not fast-forward, and have
1399                 * only one common.
1400                 */
1401                refresh_cache(REFRESH_QUIET);
1402                if (allow_trivial && fast_forward != FF_ONLY) {
1403                        /* See if it is really trivial. */
1404                        git_committer_info(IDENT_STRICT);
1405                        printf(_("Trying really trivial in-index merge...\n"));
1406                        if (!read_tree_trivial(common->item->object.sha1,
1407                                               head_commit->object.sha1,
1408                                               remoteheads->item->object.sha1)) {
1409                                ret = merge_trivial(head_commit, remoteheads);
1410                                goto done;
1411                        }
1412                        printf(_("Nope.\n"));
1413                }
1414        } else {
1415                /*
1416                 * An octopus.  If we can reach all the remote we are up
1417                 * to date.
1418                 */
1419                int up_to_date = 1;
1420                struct commit_list *j;
1421
1422                for (j = remoteheads; j; j = j->next) {
1423                        struct commit_list *common_one;
1424
1425                        /*
1426                         * Here we *have* to calculate the individual
1427                         * merge_bases again, otherwise "git merge HEAD^
1428                         * HEAD^^" would be missed.
1429                         */
1430                        common_one = get_merge_bases(head_commit, j->item, 1);
1431                        if (hashcmp(common_one->item->object.sha1,
1432                                j->item->object.sha1)) {
1433                                up_to_date = 0;
1434                                break;
1435                        }
1436                }
1437                if (up_to_date) {
1438                        finish_up_to_date("Already up-to-date. Yeeah!");
1439                        goto done;
1440                }
1441        }
1442
1443        if (fast_forward == FF_ONLY)
1444                die(_("Not possible to fast-forward, aborting."));
1445
1446        /* We are going to make a new commit. */
1447        git_committer_info(IDENT_STRICT);
1448
1449        /*
1450         * At this point, we need a real merge.  No matter what strategy
1451         * we use, it would operate on the index, possibly affecting the
1452         * working tree, and when resolved cleanly, have the desired
1453         * tree in the index -- this means that the index must be in
1454         * sync with the head commit.  The strategies are responsible
1455         * to ensure this.
1456         */
1457        if (use_strategies_nr == 1 ||
1458            /*
1459             * Stash away the local changes so that we can try more than one.
1460             */
1461            save_state(stash))
1462                hashcpy(stash, null_sha1);
1463
1464        for (i = 0; i < use_strategies_nr; i++) {
1465                int ret;
1466                if (i) {
1467                        printf(_("Rewinding the tree to pristine...\n"));
1468                        restore_state(head_commit->object.sha1, stash);
1469                }
1470                if (use_strategies_nr != 1)
1471                        printf(_("Trying merge strategy %s...\n"),
1472                                use_strategies[i]->name);
1473                /*
1474                 * Remember which strategy left the state in the working
1475                 * tree.
1476                 */
1477                wt_strategy = use_strategies[i]->name;
1478
1479                ret = try_merge_strategy(use_strategies[i]->name,
1480                                         common, remoteheads,
1481                                         head_commit, head_arg);
1482                if (!option_commit && !ret) {
1483                        merge_was_ok = 1;
1484                        /*
1485                         * This is necessary here just to avoid writing
1486                         * the tree, but later we will *not* exit with
1487                         * status code 1 because merge_was_ok is set.
1488                         */
1489                        ret = 1;
1490                }
1491
1492                if (ret) {
1493                        /*
1494                         * The backend exits with 1 when conflicts are
1495                         * left to be resolved, with 2 when it does not
1496                         * handle the given merge at all.
1497                         */
1498                        if (ret == 1) {
1499                                int cnt = evaluate_result();
1500
1501                                if (best_cnt <= 0 || cnt <= best_cnt) {
1502                                        best_strategy = use_strategies[i]->name;
1503                                        best_cnt = cnt;
1504                                }
1505                        }
1506                        if (merge_was_ok)
1507                                break;
1508                        else
1509                                continue;
1510                }
1511
1512                /* Automerge succeeded. */
1513                write_tree_trivial(result_tree);
1514                automerge_was_ok = 1;
1515                break;
1516        }
1517
1518        /*
1519         * If we have a resulting tree, that means the strategy module
1520         * auto resolved the merge cleanly.
1521         */
1522        if (automerge_was_ok) {
1523                ret = finish_automerge(head_commit, head_subsumed,
1524                                       common, remoteheads,
1525                                       result_tree, wt_strategy);
1526                goto done;
1527        }
1528
1529        /*
1530         * Pick the result from the best strategy and have the user fix
1531         * it up.
1532         */
1533        if (!best_strategy) {
1534                restore_state(head_commit->object.sha1, stash);
1535                if (use_strategies_nr > 1)
1536                        fprintf(stderr,
1537                                _("No merge strategy handled the merge.\n"));
1538                else
1539                        fprintf(stderr, _("Merge with strategy %s failed.\n"),
1540                                use_strategies[0]->name);
1541                ret = 2;
1542                goto done;
1543        } else if (best_strategy == wt_strategy)
1544                ; /* We already have its result in the working tree. */
1545        else {
1546                printf(_("Rewinding the tree to pristine...\n"));
1547                restore_state(head_commit->object.sha1, stash);
1548                printf(_("Using the %s to prepare resolving by hand.\n"),
1549                        best_strategy);
1550                try_merge_strategy(best_strategy, common, remoteheads,
1551                                   head_commit, head_arg);
1552        }
1553
1554        if (squash)
1555                finish(head_commit, remoteheads, NULL, NULL);
1556        else
1557                write_merge_state(remoteheads);
1558
1559        if (merge_was_ok)
1560                fprintf(stderr, _("Automatic merge went well; "
1561                        "stopped before committing as requested\n"));
1562        else
1563                ret = suggest_conflicts(option_renormalize);
1564
1565done:
1566        free(branch_to_free);
1567        return ret;
1568}