builtin-merge.con commit Merge branch 'bs/maint-rename-populate-filespec' (2b5189e)
   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
  28#define DEFAULT_TWOHEAD (1<<0)
  29#define DEFAULT_OCTOPUS (1<<1)
  30#define NO_FAST_FORWARD (1<<2)
  31#define NO_TRIVIAL      (1<<3)
  32
  33struct strategy {
  34        const char *name;
  35        unsigned attr;
  36};
  37
  38static const char * const builtin_merge_usage[] = {
  39        "git-merge [options] <remote>...",
  40        "git-merge [options] <msg> HEAD <remote>",
  41        NULL
  42};
  43
  44static int show_diffstat = 1, option_log, squash;
  45static int option_commit = 1, allow_fast_forward = 1;
  46static int allow_trivial = 1, have_message;
  47static struct strbuf merge_msg;
  48static struct commit_list *remoteheads;
  49static unsigned char head[20], stash[20];
  50static struct strategy **use_strategies;
  51static size_t use_strategies_nr, use_strategies_alloc;
  52static const char *branch;
  53static int verbosity;
  54
  55static struct strategy all_strategy[] = {
  56        { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
  57        { "octopus",    DEFAULT_OCTOPUS },
  58        { "resolve",    0 },
  59        { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
  60        { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
  61};
  62
  63static const char *pull_twohead, *pull_octopus;
  64
  65static int option_parse_message(const struct option *opt,
  66                                const char *arg, int unset)
  67{
  68        struct strbuf *buf = opt->value;
  69
  70        if (unset)
  71                strbuf_setlen(buf, 0);
  72        else if (arg) {
  73                strbuf_addf(buf, "%s\n\n", arg);
  74                have_message = 1;
  75        } else
  76                return error("switch `m' requires a value");
  77        return 0;
  78}
  79
  80static struct strategy *get_strategy(const char *name)
  81{
  82        int i;
  83        struct strategy *ret;
  84        static struct cmdnames main_cmds, other_cmds;
  85        static int loaded;
  86
  87        if (!name)
  88                return NULL;
  89
  90        for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
  91                if (!strcmp(name, all_strategy[i].name))
  92                        return &all_strategy[i];
  93
  94        if (!loaded) {
  95                struct cmdnames not_strategies;
  96                loaded = 1;
  97
  98                memset(&not_strategies, 0, sizeof(struct cmdnames));
  99                load_command_list("git-merge-", &main_cmds, &other_cmds);
 100                for (i = 0; i < main_cmds.cnt; i++) {
 101                        int j, found = 0;
 102                        struct cmdname *ent = main_cmds.names[i];
 103                        for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
 104                                if (!strncmp(ent->name, all_strategy[j].name, ent->len)
 105                                                && !all_strategy[j].name[ent->len])
 106                                        found = 1;
 107                        if (!found)
 108                                add_cmdname(&not_strategies, ent->name, ent->len);
 109                        exclude_cmds(&main_cmds, &not_strategies);
 110                }
 111        }
 112        if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
 113                fprintf(stderr, "Could not find merge strategy '%s'.\n", name);
 114                fprintf(stderr, "Available strategies are:");
 115                for (i = 0; i < main_cmds.cnt; i++)
 116                        fprintf(stderr, " %s", main_cmds.names[i]->name);
 117                fprintf(stderr, ".\n");
 118                if (other_cmds.cnt) {
 119                        fprintf(stderr, "Available custom strategies are:");
 120                        for (i = 0; i < other_cmds.cnt; i++)
 121                                fprintf(stderr, " %s", other_cmds.names[i]->name);
 122                        fprintf(stderr, ".\n");
 123                }
 124                exit(1);
 125        }
 126
 127        ret = xcalloc(1, sizeof(struct strategy));
 128        ret->name = xstrdup(name);
 129        return ret;
 130}
 131
 132static void append_strategy(struct strategy *s)
 133{
 134        ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
 135        use_strategies[use_strategies_nr++] = s;
 136}
 137
 138static int option_parse_strategy(const struct option *opt,
 139                                 const char *name, int unset)
 140{
 141        if (unset)
 142                return 0;
 143
 144        append_strategy(get_strategy(name));
 145        return 0;
 146}
 147
 148static int option_parse_n(const struct option *opt,
 149                          const char *arg, int unset)
 150{
 151        show_diffstat = unset;
 152        return 0;
 153}
 154
 155static struct option builtin_merge_options[] = {
 156        { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
 157                "do not show a diffstat at the end of the merge",
 158                PARSE_OPT_NOARG, option_parse_n },
 159        OPT_BOOLEAN(0, "stat", &show_diffstat,
 160                "show a diffstat at the end of the merge"),
 161        OPT_BOOLEAN(0, "summary", &show_diffstat, "(synonym to --stat)"),
 162        OPT_BOOLEAN(0, "log", &option_log,
 163                "add list of one-line log to merge commit message"),
 164        OPT_BOOLEAN(0, "squash", &squash,
 165                "create a single commit instead of doing a merge"),
 166        OPT_BOOLEAN(0, "commit", &option_commit,
 167                "perform a commit if the merge succeeds (default)"),
 168        OPT_BOOLEAN(0, "ff", &allow_fast_forward,
 169                "allow fast forward (default)"),
 170        OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
 171                "merge strategy to use", option_parse_strategy),
 172        OPT_CALLBACK('m', "message", &merge_msg, "message",
 173                "message to be used for the merge commit (if any)",
 174                option_parse_message),
 175        OPT__VERBOSITY(&verbosity),
 176        OPT_END()
 177};
 178
 179/* Cleans up metadata that is uninteresting after a succeeded merge. */
 180static void drop_save(void)
 181{
 182        unlink(git_path("MERGE_HEAD"));
 183        unlink(git_path("MERGE_MSG"));
 184        unlink(git_path("MERGE_MODE"));
 185}
 186
 187static void save_state(void)
 188{
 189        int len;
 190        struct child_process cp;
 191        struct strbuf buffer = STRBUF_INIT;
 192        const char *argv[] = {"stash", "create", NULL};
 193
 194        memset(&cp, 0, sizeof(cp));
 195        cp.argv = argv;
 196        cp.out = -1;
 197        cp.git_cmd = 1;
 198
 199        if (start_command(&cp))
 200                die("could not run stash.");
 201        len = strbuf_read(&buffer, cp.out, 1024);
 202        close(cp.out);
 203
 204        if (finish_command(&cp) || len < 0)
 205                die("stash failed");
 206        else if (!len)
 207                return;
 208        strbuf_setlen(&buffer, buffer.len-1);
 209        if (get_sha1(buffer.buf, stash))
 210                die("not a valid object: %s", buffer.buf);
 211}
 212
 213static void reset_hard(unsigned const char *sha1, int verbose)
 214{
 215        int i = 0;
 216        const char *args[6];
 217
 218        args[i++] = "read-tree";
 219        if (verbose)
 220                args[i++] = "-v";
 221        args[i++] = "--reset";
 222        args[i++] = "-u";
 223        args[i++] = sha1_to_hex(sha1);
 224        args[i] = NULL;
 225
 226        if (run_command_v_opt(args, RUN_GIT_CMD))
 227                die("read-tree failed");
 228}
 229
 230static void restore_state(void)
 231{
 232        struct strbuf sb = STRBUF_INIT;
 233        const char *args[] = { "stash", "apply", NULL, NULL };
 234
 235        if (is_null_sha1(stash))
 236                return;
 237
 238        reset_hard(head, 1);
 239
 240        args[2] = sha1_to_hex(stash);
 241
 242        /*
 243         * It is OK to ignore error here, for example when there was
 244         * nothing to restore.
 245         */
 246        run_command_v_opt(args, RUN_GIT_CMD);
 247
 248        strbuf_release(&sb);
 249        refresh_cache(REFRESH_QUIET);
 250}
 251
 252/* This is called when no merge was necessary. */
 253static void finish_up_to_date(const char *msg)
 254{
 255        if (verbosity >= 0)
 256                printf("%s%s\n", squash ? " (nothing to squash)" : "", msg);
 257        drop_save();
 258}
 259
 260static void squash_message(void)
 261{
 262        struct rev_info rev;
 263        struct commit *commit;
 264        struct strbuf out = STRBUF_INIT;
 265        struct commit_list *j;
 266        int fd;
 267
 268        printf("Squash commit -- not updating HEAD\n");
 269        fd = open(git_path("SQUASH_MSG"), O_WRONLY | O_CREAT, 0666);
 270        if (fd < 0)
 271                die("Could not write to %s", git_path("SQUASH_MSG"));
 272
 273        init_revisions(&rev, NULL);
 274        rev.ignore_merges = 1;
 275        rev.commit_format = CMIT_FMT_MEDIUM;
 276
 277        commit = lookup_commit(head);
 278        commit->object.flags |= UNINTERESTING;
 279        add_pending_object(&rev, &commit->object, NULL);
 280
 281        for (j = remoteheads; j; j = j->next)
 282                add_pending_object(&rev, &j->item->object, NULL);
 283
 284        setup_revisions(0, NULL, &rev, NULL);
 285        if (prepare_revision_walk(&rev))
 286                die("revision walk setup failed");
 287
 288        strbuf_addstr(&out, "Squashed commit of the following:\n");
 289        while ((commit = get_revision(&rev)) != NULL) {
 290                strbuf_addch(&out, '\n');
 291                strbuf_addf(&out, "commit %s\n",
 292                        sha1_to_hex(commit->object.sha1));
 293                pretty_print_commit(rev.commit_format, commit, &out, rev.abbrev,
 294                        NULL, NULL, rev.date_mode, 0);
 295        }
 296        if (write(fd, out.buf, out.len) < 0)
 297                die("Writing SQUASH_MSG: %s", strerror(errno));
 298        if (close(fd))
 299                die("Finishing SQUASH_MSG: %s", strerror(errno));
 300        strbuf_release(&out);
 301}
 302
 303static int run_hook(const char *name)
 304{
 305        struct child_process hook;
 306        const char *argv[3], *env[2];
 307        char index[PATH_MAX];
 308
 309        argv[0] = git_path("hooks/%s", name);
 310        if (access(argv[0], X_OK) < 0)
 311                return 0;
 312
 313        snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", get_index_file());
 314        env[0] = index;
 315        env[1] = NULL;
 316
 317        if (squash)
 318                argv[1] = "1";
 319        else
 320                argv[1] = "0";
 321        argv[2] = NULL;
 322
 323        memset(&hook, 0, sizeof(hook));
 324        hook.argv = argv;
 325        hook.no_stdin = 1;
 326        hook.stdout_to_stderr = 1;
 327        hook.env = env;
 328
 329        return run_command(&hook);
 330}
 331
 332static void finish(const unsigned char *new_head, const char *msg)
 333{
 334        struct strbuf reflog_message = STRBUF_INIT;
 335
 336        if (!msg)
 337                strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
 338        else {
 339                if (verbosity >= 0)
 340                        printf("%s\n", msg);
 341                strbuf_addf(&reflog_message, "%s: %s",
 342                        getenv("GIT_REFLOG_ACTION"), msg);
 343        }
 344        if (squash) {
 345                squash_message();
 346        } else {
 347                if (verbosity >= 0 && !merge_msg.len)
 348                        printf("No merge message -- not updating HEAD\n");
 349                else {
 350                        const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 351                        update_ref(reflog_message.buf, "HEAD",
 352                                new_head, head, 0,
 353                                DIE_ON_ERR);
 354                        /*
 355                         * We ignore errors in 'gc --auto', since the
 356                         * user should see them.
 357                         */
 358                        run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 359                }
 360        }
 361        if (new_head && show_diffstat) {
 362                struct diff_options opts;
 363                diff_setup(&opts);
 364                opts.output_format |=
 365                        DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 366                opts.detect_rename = DIFF_DETECT_RENAME;
 367                if (diff_use_color_default > 0)
 368                        DIFF_OPT_SET(&opts, COLOR_DIFF);
 369                if (diff_setup_done(&opts) < 0)
 370                        die("diff_setup_done failed");
 371                diff_tree_sha1(head, new_head, "", &opts);
 372                diffcore_std(&opts);
 373                diff_flush(&opts);
 374        }
 375
 376        /* Run a post-merge hook */
 377        run_hook("post-merge");
 378
 379        strbuf_release(&reflog_message);
 380}
 381
 382/* Get the name for the merge commit's message. */
 383static void merge_name(const char *remote, struct strbuf *msg)
 384{
 385        struct object *remote_head;
 386        unsigned char branch_head[20], buf_sha[20];
 387        struct strbuf buf = STRBUF_INIT;
 388        const char *ptr;
 389        int len, early;
 390
 391        memset(branch_head, 0, sizeof(branch_head));
 392        remote_head = peel_to_type(remote, 0, NULL, OBJ_COMMIT);
 393        if (!remote_head)
 394                die("'%s' does not point to a commit", remote);
 395
 396        strbuf_addstr(&buf, "refs/heads/");
 397        strbuf_addstr(&buf, remote);
 398        resolve_ref(buf.buf, branch_head, 0, 0);
 399
 400        if (!hashcmp(remote_head->sha1, branch_head)) {
 401                strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 402                        sha1_to_hex(branch_head), remote);
 403                return;
 404        }
 405
 406        /* See if remote matches <name>^^^.. or <name>~<number> */
 407        for (len = 0, ptr = remote + strlen(remote);
 408             remote < ptr && ptr[-1] == '^';
 409             ptr--)
 410                len++;
 411        if (len)
 412                early = 1;
 413        else {
 414                early = 0;
 415                ptr = strrchr(remote, '~');
 416                if (ptr) {
 417                        int seen_nonzero = 0;
 418
 419                        len++; /* count ~ */
 420                        while (*++ptr && isdigit(*ptr)) {
 421                                seen_nonzero |= (*ptr != '0');
 422                                len++;
 423                        }
 424                        if (*ptr)
 425                                len = 0; /* not ...~<number> */
 426                        else if (seen_nonzero)
 427                                early = 1;
 428                        else if (len == 1)
 429                                early = 1; /* "name~" is "name~1"! */
 430                }
 431        }
 432        if (len) {
 433                struct strbuf truname = STRBUF_INIT;
 434                strbuf_addstr(&truname, "refs/heads/");
 435                strbuf_addstr(&truname, remote);
 436                strbuf_setlen(&truname, truname.len - len);
 437                if (resolve_ref(truname.buf, buf_sha, 0, 0)) {
 438                        strbuf_addf(msg,
 439                                    "%s\t\tbranch '%s'%s of .\n",
 440                                    sha1_to_hex(remote_head->sha1),
 441                                    truname.buf + 11,
 442                                    (early ? " (early part)" : ""));
 443                        return;
 444                }
 445        }
 446
 447        if (!strcmp(remote, "FETCH_HEAD") &&
 448                        !access(git_path("FETCH_HEAD"), R_OK)) {
 449                FILE *fp;
 450                struct strbuf line = STRBUF_INIT;
 451                char *ptr;
 452
 453                fp = fopen(git_path("FETCH_HEAD"), "r");
 454                if (!fp)
 455                        die("could not open %s for reading: %s",
 456                                git_path("FETCH_HEAD"), strerror(errno));
 457                strbuf_getline(&line, fp, '\n');
 458                fclose(fp);
 459                ptr = strstr(line.buf, "\tnot-for-merge\t");
 460                if (ptr)
 461                        strbuf_remove(&line, ptr-line.buf+1, 13);
 462                strbuf_addbuf(msg, &line);
 463                strbuf_release(&line);
 464                return;
 465        }
 466        strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 467                sha1_to_hex(remote_head->sha1), remote);
 468}
 469
 470static int git_merge_config(const char *k, const char *v, void *cb)
 471{
 472        if (branch && !prefixcmp(k, "branch.") &&
 473                !prefixcmp(k + 7, branch) &&
 474                !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
 475                const char **argv;
 476                int argc;
 477                char *buf;
 478
 479                buf = xstrdup(v);
 480                argc = split_cmdline(buf, &argv);
 481                if (argc < 0)
 482                        die("Bad branch.%s.mergeoptions string", branch);
 483                argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
 484                memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
 485                argc++;
 486                parse_options(argc, argv, builtin_merge_options,
 487                              builtin_merge_usage, 0);
 488                free(buf);
 489        }
 490
 491        if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 492                show_diffstat = git_config_bool(k, v);
 493        else if (!strcmp(k, "pull.twohead"))
 494                return git_config_string(&pull_twohead, k, v);
 495        else if (!strcmp(k, "pull.octopus"))
 496                return git_config_string(&pull_octopus, k, v);
 497        else if (!strcmp(k, "merge.log") || !strcmp(k, "merge.summary"))
 498                option_log = git_config_bool(k, v);
 499        return git_diff_ui_config(k, v, cb);
 500}
 501
 502static int read_tree_trivial(unsigned char *common, unsigned char *head,
 503                             unsigned char *one)
 504{
 505        int i, nr_trees = 0;
 506        struct tree *trees[MAX_UNPACK_TREES];
 507        struct tree_desc t[MAX_UNPACK_TREES];
 508        struct unpack_trees_options opts;
 509
 510        memset(&opts, 0, sizeof(opts));
 511        opts.head_idx = 2;
 512        opts.src_index = &the_index;
 513        opts.dst_index = &the_index;
 514        opts.update = 1;
 515        opts.verbose_update = 1;
 516        opts.trivial_merges_only = 1;
 517        opts.merge = 1;
 518        trees[nr_trees] = parse_tree_indirect(common);
 519        if (!trees[nr_trees++])
 520                return -1;
 521        trees[nr_trees] = parse_tree_indirect(head);
 522        if (!trees[nr_trees++])
 523                return -1;
 524        trees[nr_trees] = parse_tree_indirect(one);
 525        if (!trees[nr_trees++])
 526                return -1;
 527        opts.fn = threeway_merge;
 528        cache_tree_free(&active_cache_tree);
 529        for (i = 0; i < nr_trees; i++) {
 530                parse_tree(trees[i]);
 531                init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 532        }
 533        if (unpack_trees(nr_trees, t, &opts))
 534                return -1;
 535        return 0;
 536}
 537
 538static void write_tree_trivial(unsigned char *sha1)
 539{
 540        if (write_cache_as_tree(sha1, 0, NULL))
 541                die("git write-tree failed to write a tree");
 542}
 543
 544static int try_merge_strategy(const char *strategy, struct commit_list *common,
 545                              const char *head_arg)
 546{
 547        const char **args;
 548        int i = 0, ret;
 549        struct commit_list *j;
 550        struct strbuf buf = STRBUF_INIT;
 551        int index_fd;
 552        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 553
 554        index_fd = hold_locked_index(lock, 1);
 555        refresh_cache(REFRESH_QUIET);
 556        if (active_cache_changed &&
 557                        (write_cache(index_fd, active_cache, active_nr) ||
 558                         commit_locked_index(lock)))
 559                return error("Unable to write index.");
 560        rollback_lock_file(lock);
 561
 562        if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
 563                int clean;
 564                struct commit *result;
 565                struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 566                int index_fd;
 567                struct commit_list *reversed = NULL;
 568                struct merge_options o;
 569
 570                if (remoteheads->next) {
 571                        error("Not handling anything other than two heads merge.");
 572                        return 2;
 573                }
 574
 575                init_merge_options(&o);
 576                if (!strcmp(strategy, "subtree"))
 577                        o.subtree_merge = 1;
 578
 579                o.branch1 = head_arg;
 580                o.branch2 = remoteheads->item->util;
 581
 582                for (j = common; j; j = j->next)
 583                        commit_list_insert(j->item, &reversed);
 584
 585                index_fd = hold_locked_index(lock, 1);
 586                clean = merge_recursive(&o, lookup_commit(head),
 587                                remoteheads->item, reversed, &result);
 588                if (active_cache_changed &&
 589                                (write_cache(index_fd, active_cache, active_nr) ||
 590                                 commit_locked_index(lock)))
 591                        die ("unable to write %s", get_index_file());
 592                rollback_lock_file(lock);
 593                return clean ? 0 : 1;
 594        } else {
 595                args = xmalloc((4 + commit_list_count(common) +
 596                                        commit_list_count(remoteheads)) * sizeof(char *));
 597                strbuf_addf(&buf, "merge-%s", strategy);
 598                args[i++] = buf.buf;
 599                for (j = common; j; j = j->next)
 600                        args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
 601                args[i++] = "--";
 602                args[i++] = head_arg;
 603                for (j = remoteheads; j; j = j->next)
 604                        args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
 605                args[i] = NULL;
 606                ret = run_command_v_opt(args, RUN_GIT_CMD);
 607                strbuf_release(&buf);
 608                i = 1;
 609                for (j = common; j; j = j->next)
 610                        free((void *)args[i++]);
 611                i += 2;
 612                for (j = remoteheads; j; j = j->next)
 613                        free((void *)args[i++]);
 614                free(args);
 615                discard_cache();
 616                if (read_cache() < 0)
 617                        die("failed to read the cache");
 618                return -ret;
 619        }
 620}
 621
 622static void count_diff_files(struct diff_queue_struct *q,
 623                             struct diff_options *opt, void *data)
 624{
 625        int *count = data;
 626
 627        (*count) += q->nr;
 628}
 629
 630static int count_unmerged_entries(void)
 631{
 632        const struct index_state *state = &the_index;
 633        int i, ret = 0;
 634
 635        for (i = 0; i < state->cache_nr; i++)
 636                if (ce_stage(state->cache[i]))
 637                        ret++;
 638
 639        return ret;
 640}
 641
 642static int checkout_fast_forward(unsigned char *head, unsigned char *remote)
 643{
 644        struct tree *trees[MAX_UNPACK_TREES];
 645        struct unpack_trees_options opts;
 646        struct tree_desc t[MAX_UNPACK_TREES];
 647        int i, fd, nr_trees = 0;
 648        struct dir_struct dir;
 649        struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 650
 651        refresh_cache(REFRESH_QUIET);
 652
 653        fd = hold_locked_index(lock_file, 1);
 654
 655        memset(&trees, 0, sizeof(trees));
 656        memset(&opts, 0, sizeof(opts));
 657        memset(&t, 0, sizeof(t));
 658        memset(&dir, 0, sizeof(dir));
 659        dir.show_ignored = 1;
 660        dir.exclude_per_dir = ".gitignore";
 661        opts.dir = &dir;
 662
 663        opts.head_idx = 1;
 664        opts.src_index = &the_index;
 665        opts.dst_index = &the_index;
 666        opts.update = 1;
 667        opts.verbose_update = 1;
 668        opts.merge = 1;
 669        opts.fn = twoway_merge;
 670
 671        trees[nr_trees] = parse_tree_indirect(head);
 672        if (!trees[nr_trees++])
 673                return -1;
 674        trees[nr_trees] = parse_tree_indirect(remote);
 675        if (!trees[nr_trees++])
 676                return -1;
 677        for (i = 0; i < nr_trees; i++) {
 678                parse_tree(trees[i]);
 679                init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 680        }
 681        if (unpack_trees(nr_trees, t, &opts))
 682                return -1;
 683        if (write_cache(fd, active_cache, active_nr) ||
 684                commit_locked_index(lock_file))
 685                die("unable to write new index file");
 686        return 0;
 687}
 688
 689static void split_merge_strategies(const char *string, struct strategy **list,
 690                                   int *nr, int *alloc)
 691{
 692        char *p, *q, *buf;
 693
 694        if (!string)
 695                return;
 696
 697        buf = xstrdup(string);
 698        q = buf;
 699        for (;;) {
 700                p = strchr(q, ' ');
 701                if (!p) {
 702                        ALLOC_GROW(*list, *nr + 1, *alloc);
 703                        (*list)[(*nr)++].name = xstrdup(q);
 704                        free(buf);
 705                        return;
 706                } else {
 707                        *p = '\0';
 708                        ALLOC_GROW(*list, *nr + 1, *alloc);
 709                        (*list)[(*nr)++].name = xstrdup(q);
 710                        q = ++p;
 711                }
 712        }
 713}
 714
 715static void add_strategies(const char *string, unsigned attr)
 716{
 717        struct strategy *list = NULL;
 718        int list_alloc = 0, list_nr = 0, i;
 719
 720        memset(&list, 0, sizeof(list));
 721        split_merge_strategies(string, &list, &list_nr, &list_alloc);
 722        if (list) {
 723                for (i = 0; i < list_nr; i++)
 724                        append_strategy(get_strategy(list[i].name));
 725                return;
 726        }
 727        for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 728                if (all_strategy[i].attr & attr)
 729                        append_strategy(&all_strategy[i]);
 730
 731}
 732
 733static int merge_trivial(void)
 734{
 735        unsigned char result_tree[20], result_commit[20];
 736        struct commit_list *parent = xmalloc(sizeof(*parent));
 737
 738        write_tree_trivial(result_tree);
 739        printf("Wonderful.\n");
 740        parent->item = lookup_commit(head);
 741        parent->next = xmalloc(sizeof(*parent->next));
 742        parent->next->item = remoteheads->item;
 743        parent->next->next = NULL;
 744        commit_tree(merge_msg.buf, result_tree, parent, result_commit, NULL);
 745        finish(result_commit, "In-index merge");
 746        drop_save();
 747        return 0;
 748}
 749
 750static int finish_automerge(struct commit_list *common,
 751                            unsigned char *result_tree,
 752                            const char *wt_strategy)
 753{
 754        struct commit_list *parents = NULL, *j;
 755        struct strbuf buf = STRBUF_INIT;
 756        unsigned char result_commit[20];
 757
 758        free_commit_list(common);
 759        if (allow_fast_forward) {
 760                parents = remoteheads;
 761                commit_list_insert(lookup_commit(head), &parents);
 762                parents = reduce_heads(parents);
 763        } else {
 764                struct commit_list **pptr = &parents;
 765
 766                pptr = &commit_list_insert(lookup_commit(head),
 767                                pptr)->next;
 768                for (j = remoteheads; j; j = j->next)
 769                        pptr = &commit_list_insert(j->item, pptr)->next;
 770        }
 771        free_commit_list(remoteheads);
 772        strbuf_addch(&merge_msg, '\n');
 773        commit_tree(merge_msg.buf, result_tree, parents, result_commit, NULL);
 774        strbuf_addf(&buf, "Merge made by %s.", wt_strategy);
 775        finish(result_commit, buf.buf);
 776        strbuf_release(&buf);
 777        drop_save();
 778        return 0;
 779}
 780
 781static int suggest_conflicts(void)
 782{
 783        FILE *fp;
 784        int pos;
 785
 786        fp = fopen(git_path("MERGE_MSG"), "a");
 787        if (!fp)
 788                die("Could open %s for writing", git_path("MERGE_MSG"));
 789        fprintf(fp, "\nConflicts:\n");
 790        for (pos = 0; pos < active_nr; pos++) {
 791                struct cache_entry *ce = active_cache[pos];
 792
 793                if (ce_stage(ce)) {
 794                        fprintf(fp, "\t%s\n", ce->name);
 795                        while (pos + 1 < active_nr &&
 796                                        !strcmp(ce->name,
 797                                                active_cache[pos + 1]->name))
 798                                pos++;
 799                }
 800        }
 801        fclose(fp);
 802        rerere();
 803        printf("Automatic merge failed; "
 804                        "fix conflicts and then commit the result.\n");
 805        return 1;
 806}
 807
 808static struct commit *is_old_style_invocation(int argc, const char **argv)
 809{
 810        struct commit *second_token = NULL;
 811        if (argc > 1) {
 812                unsigned char second_sha1[20];
 813
 814                if (get_sha1(argv[1], second_sha1))
 815                        return NULL;
 816                second_token = lookup_commit_reference_gently(second_sha1, 0);
 817                if (!second_token)
 818                        die("'%s' is not a commit", argv[1]);
 819                if (hashcmp(second_token->object.sha1, head))
 820                        return NULL;
 821        }
 822        return second_token;
 823}
 824
 825static int evaluate_result(void)
 826{
 827        int cnt = 0;
 828        struct rev_info rev;
 829
 830        /* Check how many files differ. */
 831        init_revisions(&rev, "");
 832        setup_revisions(0, NULL, &rev, NULL);
 833        rev.diffopt.output_format |=
 834                DIFF_FORMAT_CALLBACK;
 835        rev.diffopt.format_callback = count_diff_files;
 836        rev.diffopt.format_callback_data = &cnt;
 837        run_diff_files(&rev, 0);
 838
 839        /*
 840         * Check how many unmerged entries are
 841         * there.
 842         */
 843        cnt += count_unmerged_entries();
 844
 845        return cnt;
 846}
 847
 848int cmd_merge(int argc, const char **argv, const char *prefix)
 849{
 850        unsigned char result_tree[20];
 851        struct strbuf buf = STRBUF_INIT;
 852        const char *head_arg;
 853        int flag, head_invalid = 0, i;
 854        int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
 855        struct commit_list *common = NULL;
 856        const char *best_strategy = NULL, *wt_strategy = NULL;
 857        struct commit_list **remotes = &remoteheads;
 858
 859        setup_work_tree();
 860        if (read_cache_unmerged())
 861                die("You are in the middle of a conflicted merge.");
 862
 863        /*
 864         * Check if we are _not_ on a detached HEAD, i.e. if there is a
 865         * current branch.
 866         */
 867        branch = resolve_ref("HEAD", head, 0, &flag);
 868        if (branch && !prefixcmp(branch, "refs/heads/"))
 869                branch += 11;
 870        if (is_null_sha1(head))
 871                head_invalid = 1;
 872
 873        git_config(git_merge_config, NULL);
 874
 875        /* for color.ui */
 876        if (diff_use_color_default == -1)
 877                diff_use_color_default = git_use_color_default;
 878
 879        argc = parse_options(argc, argv, builtin_merge_options,
 880                        builtin_merge_usage, 0);
 881        if (verbosity < 0)
 882                show_diffstat = 0;
 883
 884        if (squash) {
 885                if (!allow_fast_forward)
 886                        die("You cannot combine --squash with --no-ff.");
 887                option_commit = 0;
 888        }
 889
 890        if (!argc)
 891                usage_with_options(builtin_merge_usage,
 892                        builtin_merge_options);
 893
 894        /*
 895         * This could be traditional "merge <msg> HEAD <commit>..."  and
 896         * the way we can tell it is to see if the second token is HEAD,
 897         * but some people might have misused the interface and used a
 898         * committish that is the same as HEAD there instead.
 899         * Traditional format never would have "-m" so it is an
 900         * additional safety measure to check for it.
 901         */
 902
 903        if (!have_message && is_old_style_invocation(argc, argv)) {
 904                strbuf_addstr(&merge_msg, argv[0]);
 905                head_arg = argv[1];
 906                argv += 2;
 907                argc -= 2;
 908        } else if (head_invalid) {
 909                struct object *remote_head;
 910                /*
 911                 * If the merged head is a valid one there is no reason
 912                 * to forbid "git merge" into a branch yet to be born.
 913                 * We do the same for "git pull".
 914                 */
 915                if (argc != 1)
 916                        die("Can merge only exactly one commit into "
 917                                "empty head");
 918                if (squash)
 919                        die("Squash commit into empty head not supported yet");
 920                if (!allow_fast_forward)
 921                        die("Non-fast-forward commit does not make sense into "
 922                            "an empty head");
 923                remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT);
 924                if (!remote_head)
 925                        die("%s - not something we can merge", argv[0]);
 926                update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
 927                                DIE_ON_ERR);
 928                reset_hard(remote_head->sha1, 0);
 929                return 0;
 930        } else {
 931                struct strbuf msg = STRBUF_INIT;
 932
 933                /* We are invoked directly as the first-class UI. */
 934                head_arg = "HEAD";
 935
 936                /*
 937                 * All the rest are the commits being merged;
 938                 * prepare the standard merge summary message to
 939                 * be appended to the given message.  If remote
 940                 * is invalid we will die later in the common
 941                 * codepath so we discard the error in this
 942                 * loop.
 943                 */
 944                for (i = 0; i < argc; i++)
 945                        merge_name(argv[i], &msg);
 946                fmt_merge_msg(option_log, &msg, &merge_msg);
 947                if (merge_msg.len)
 948                        strbuf_setlen(&merge_msg, merge_msg.len-1);
 949        }
 950
 951        if (head_invalid || !argc)
 952                usage_with_options(builtin_merge_usage,
 953                        builtin_merge_options);
 954
 955        strbuf_addstr(&buf, "merge");
 956        for (i = 0; i < argc; i++)
 957                strbuf_addf(&buf, " %s", argv[i]);
 958        setenv("GIT_REFLOG_ACTION", buf.buf, 0);
 959        strbuf_reset(&buf);
 960
 961        for (i = 0; i < argc; i++) {
 962                struct object *o;
 963                struct commit *commit;
 964
 965                o = peel_to_type(argv[i], 0, NULL, OBJ_COMMIT);
 966                if (!o)
 967                        die("%s - not something we can merge", argv[i]);
 968                commit = lookup_commit(o->sha1);
 969                commit->util = (void *)argv[i];
 970                remotes = &commit_list_insert(commit, remotes)->next;
 971
 972                strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
 973                setenv(buf.buf, argv[i], 1);
 974                strbuf_reset(&buf);
 975        }
 976
 977        if (!use_strategies) {
 978                if (!remoteheads->next)
 979                        add_strategies(pull_twohead, DEFAULT_TWOHEAD);
 980                else
 981                        add_strategies(pull_octopus, DEFAULT_OCTOPUS);
 982        }
 983
 984        for (i = 0; i < use_strategies_nr; i++) {
 985                if (use_strategies[i]->attr & NO_FAST_FORWARD)
 986                        allow_fast_forward = 0;
 987                if (use_strategies[i]->attr & NO_TRIVIAL)
 988                        allow_trivial = 0;
 989        }
 990
 991        if (!remoteheads->next)
 992                common = get_merge_bases(lookup_commit(head),
 993                                remoteheads->item, 1);
 994        else {
 995                struct commit_list *list = remoteheads;
 996                commit_list_insert(lookup_commit(head), &list);
 997                common = get_octopus_merge_bases(list);
 998                free(list);
 999        }
1000
1001        update_ref("updating ORIG_HEAD", "ORIG_HEAD", head, NULL, 0,
1002                DIE_ON_ERR);
1003
1004        if (!common)
1005                ; /* No common ancestors found. We need a real merge. */
1006        else if (!remoteheads->next && !common->next &&
1007                        common->item == remoteheads->item) {
1008                /*
1009                 * If head can reach all the merge then we are up to date.
1010                 * but first the most common case of merging one remote.
1011                 */
1012                finish_up_to_date("Already up-to-date.");
1013                return 0;
1014        } else if (allow_fast_forward && !remoteheads->next &&
1015                        !common->next &&
1016                        !hashcmp(common->item->object.sha1, head)) {
1017                /* Again the most common case of merging one remote. */
1018                struct strbuf msg = STRBUF_INIT;
1019                struct object *o;
1020                char hex[41];
1021
1022                strcpy(hex, find_unique_abbrev(head, DEFAULT_ABBREV));
1023
1024                if (verbosity >= 0)
1025                        printf("Updating %s..%s\n",
1026                                hex,
1027                                find_unique_abbrev(remoteheads->item->object.sha1,
1028                                DEFAULT_ABBREV));
1029                strbuf_addstr(&msg, "Fast forward");
1030                if (have_message)
1031                        strbuf_addstr(&msg,
1032                                " (no commit created; -m option ignored)");
1033                o = peel_to_type(sha1_to_hex(remoteheads->item->object.sha1),
1034                        0, NULL, OBJ_COMMIT);
1035                if (!o)
1036                        return 1;
1037
1038                if (checkout_fast_forward(head, remoteheads->item->object.sha1))
1039                        return 1;
1040
1041                finish(o->sha1, msg.buf);
1042                drop_save();
1043                return 0;
1044        } else if (!remoteheads->next && common->next)
1045                ;
1046                /*
1047                 * We are not doing octopus and not fast forward.  Need
1048                 * a real merge.
1049                 */
1050        else if (!remoteheads->next && !common->next && option_commit) {
1051                /*
1052                 * We are not doing octopus, not fast forward, and have
1053                 * only one common.
1054                 */
1055                refresh_cache(REFRESH_QUIET);
1056                if (allow_trivial) {
1057                        /* See if it is really trivial. */
1058                        git_committer_info(IDENT_ERROR_ON_NO_NAME);
1059                        printf("Trying really trivial in-index merge...\n");
1060                        if (!read_tree_trivial(common->item->object.sha1,
1061                                        head, remoteheads->item->object.sha1))
1062                                return merge_trivial();
1063                        printf("Nope.\n");
1064                }
1065        } else {
1066                /*
1067                 * An octopus.  If we can reach all the remote we are up
1068                 * to date.
1069                 */
1070                int up_to_date = 1;
1071                struct commit_list *j;
1072
1073                for (j = remoteheads; j; j = j->next) {
1074                        struct commit_list *common_one;
1075
1076                        /*
1077                         * Here we *have* to calculate the individual
1078                         * merge_bases again, otherwise "git merge HEAD^
1079                         * HEAD^^" would be missed.
1080                         */
1081                        common_one = get_merge_bases(lookup_commit(head),
1082                                j->item, 1);
1083                        if (hashcmp(common_one->item->object.sha1,
1084                                j->item->object.sha1)) {
1085                                up_to_date = 0;
1086                                break;
1087                        }
1088                }
1089                if (up_to_date) {
1090                        finish_up_to_date("Already up-to-date. Yeeah!");
1091                        return 0;
1092                }
1093        }
1094
1095        /* We are going to make a new commit. */
1096        git_committer_info(IDENT_ERROR_ON_NO_NAME);
1097
1098        /*
1099         * At this point, we need a real merge.  No matter what strategy
1100         * we use, it would operate on the index, possibly affecting the
1101         * working tree, and when resolved cleanly, have the desired
1102         * tree in the index -- this means that the index must be in
1103         * sync with the head commit.  The strategies are responsible
1104         * to ensure this.
1105         */
1106        if (use_strategies_nr != 1) {
1107                /*
1108                 * Stash away the local changes so that we can try more
1109                 * than one.
1110                 */
1111                save_state();
1112        } else {
1113                memcpy(stash, null_sha1, 20);
1114        }
1115
1116        for (i = 0; i < use_strategies_nr; i++) {
1117                int ret;
1118                if (i) {
1119                        printf("Rewinding the tree to pristine...\n");
1120                        restore_state();
1121                }
1122                if (use_strategies_nr != 1)
1123                        printf("Trying merge strategy %s...\n",
1124                                use_strategies[i]->name);
1125                /*
1126                 * Remember which strategy left the state in the working
1127                 * tree.
1128                 */
1129                wt_strategy = use_strategies[i]->name;
1130
1131                ret = try_merge_strategy(use_strategies[i]->name,
1132                        common, head_arg);
1133                if (!option_commit && !ret) {
1134                        merge_was_ok = 1;
1135                        /*
1136                         * This is necessary here just to avoid writing
1137                         * the tree, but later we will *not* exit with
1138                         * status code 1 because merge_was_ok is set.
1139                         */
1140                        ret = 1;
1141                }
1142
1143                if (ret) {
1144                        /*
1145                         * The backend exits with 1 when conflicts are
1146                         * left to be resolved, with 2 when it does not
1147                         * handle the given merge at all.
1148                         */
1149                        if (ret == 1) {
1150                                int cnt = evaluate_result();
1151
1152                                if (best_cnt <= 0 || cnt <= best_cnt) {
1153                                        best_strategy = use_strategies[i]->name;
1154                                        best_cnt = cnt;
1155                                }
1156                        }
1157                        if (merge_was_ok)
1158                                break;
1159                        else
1160                                continue;
1161                }
1162
1163                /* Automerge succeeded. */
1164                write_tree_trivial(result_tree);
1165                automerge_was_ok = 1;
1166                break;
1167        }
1168
1169        /*
1170         * If we have a resulting tree, that means the strategy module
1171         * auto resolved the merge cleanly.
1172         */
1173        if (automerge_was_ok)
1174                return finish_automerge(common, result_tree, wt_strategy);
1175
1176        /*
1177         * Pick the result from the best strategy and have the user fix
1178         * it up.
1179         */
1180        if (!best_strategy) {
1181                restore_state();
1182                if (use_strategies_nr > 1)
1183                        fprintf(stderr,
1184                                "No merge strategy handled the merge.\n");
1185                else
1186                        fprintf(stderr, "Merge with strategy %s failed.\n",
1187                                use_strategies[0]->name);
1188                return 2;
1189        } else if (best_strategy == wt_strategy)
1190                ; /* We already have its result in the working tree. */
1191        else {
1192                printf("Rewinding the tree to pristine...\n");
1193                restore_state();
1194                printf("Using the %s to prepare resolving by hand.\n",
1195                        best_strategy);
1196                try_merge_strategy(best_strategy, common, head_arg);
1197        }
1198
1199        if (squash)
1200                finish(NULL, NULL);
1201        else {
1202                int fd;
1203                struct commit_list *j;
1204
1205                for (j = remoteheads; j; j = j->next)
1206                        strbuf_addf(&buf, "%s\n",
1207                                sha1_to_hex(j->item->object.sha1));
1208                fd = open(git_path("MERGE_HEAD"), O_WRONLY | O_CREAT, 0666);
1209                if (fd < 0)
1210                        die("Could open %s for writing",
1211                                git_path("MERGE_HEAD"));
1212                if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1213                        die("Could not write to %s", git_path("MERGE_HEAD"));
1214                close(fd);
1215                strbuf_addch(&merge_msg, '\n');
1216                fd = open(git_path("MERGE_MSG"), O_WRONLY | O_CREAT, 0666);
1217                if (fd < 0)
1218                        die("Could open %s for writing", git_path("MERGE_MSG"));
1219                if (write_in_full(fd, merge_msg.buf, merge_msg.len) !=
1220                        merge_msg.len)
1221                        die("Could not write to %s", git_path("MERGE_MSG"));
1222                close(fd);
1223                fd = open(git_path("MERGE_MODE"), O_WRONLY | O_CREAT | O_TRUNC, 0666);
1224                if (fd < 0)
1225                        die("Could open %s for writing", git_path("MERGE_MODE"));
1226                strbuf_reset(&buf);
1227                if (!allow_fast_forward)
1228                        strbuf_addf(&buf, "no-ff");
1229                if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1230                        die("Could not write to %s", git_path("MERGE_MODE"));
1231                close(fd);
1232        }
1233
1234        if (merge_was_ok) {
1235                fprintf(stderr, "Automatic merge went well; "
1236                        "stopped before committing as requested\n");
1237                return 0;
1238        } else
1239                return suggest_conflicts();
1240}