builtin / clone.con commit Merge branch 'maint' (c4a01a3)
   1/*
   2 * Builtin "git clone"
   3 *
   4 * Copyright (c) 2007 Kristian Høgsberg <krh@redhat.com>,
   5 *               2008 Daniel Barkalow <barkalow@iabervon.org>
   6 * Based on git-commit.sh by Junio C Hamano and Linus Torvalds
   7 *
   8 * Clone a repository into a different directory that does not yet exist.
   9 */
  10
  11#include "builtin.h"
  12#include "parse-options.h"
  13#include "fetch-pack.h"
  14#include "refs.h"
  15#include "tree.h"
  16#include "tree-walk.h"
  17#include "unpack-trees.h"
  18#include "transport.h"
  19#include "strbuf.h"
  20#include "dir.h"
  21#include "pack-refs.h"
  22#include "sigchain.h"
  23#include "branch.h"
  24#include "remote.h"
  25#include "run-command.h"
  26
  27/*
  28 * Overall FIXMEs:
  29 *  - respect DB_ENVIRONMENT for .git/objects.
  30 *
  31 * Implementation notes:
  32 *  - dropping use-separate-remote and no-separate-remote compatibility
  33 *
  34 */
  35static const char * const builtin_clone_usage[] = {
  36        "git clone [options] [--] <repo> [<dir>]",
  37        NULL
  38};
  39
  40static int option_no_checkout, option_bare, option_mirror;
  41static int option_local, option_no_hardlinks, option_shared, option_recursive;
  42static char *option_template, *option_depth;
  43static char *option_origin = NULL;
  44static char *option_branch = NULL;
  45static const char *real_git_dir;
  46static char *option_upload_pack = "git-upload-pack";
  47static int option_verbosity;
  48static int option_progress;
  49static struct string_list option_config;
  50static struct string_list option_reference;
  51
  52static int opt_parse_reference(const struct option *opt, const char *arg, int unset)
  53{
  54        struct string_list *option_reference = opt->value;
  55        if (!arg)
  56                return -1;
  57        string_list_append(option_reference, arg);
  58        return 0;
  59}
  60
  61static struct option builtin_clone_options[] = {
  62        OPT__VERBOSITY(&option_verbosity),
  63        OPT_BOOLEAN(0, "progress", &option_progress,
  64                        "force progress reporting"),
  65        OPT_BOOLEAN('n', "no-checkout", &option_no_checkout,
  66                    "don't create a checkout"),
  67        OPT_BOOLEAN(0, "bare", &option_bare, "create a bare repository"),
  68        { OPTION_BOOLEAN, 0, "naked", &option_bare, NULL,
  69                "create a bare repository",
  70                PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
  71        OPT_BOOLEAN(0, "mirror", &option_mirror,
  72                    "create a mirror repository (implies bare)"),
  73        OPT_BOOLEAN('l', "local", &option_local,
  74                    "to clone from a local repository"),
  75        OPT_BOOLEAN(0, "no-hardlinks", &option_no_hardlinks,
  76                    "don't use local hardlinks, always copy"),
  77        OPT_BOOLEAN('s', "shared", &option_shared,
  78                    "setup as shared repository"),
  79        OPT_BOOLEAN(0, "recursive", &option_recursive,
  80                    "initialize submodules in the clone"),
  81        OPT_BOOLEAN(0, "recurse-submodules", &option_recursive,
  82                    "initialize submodules in the clone"),
  83        OPT_STRING(0, "template", &option_template, "template-directory",
  84                   "directory from which templates will be used"),
  85        OPT_CALLBACK(0 , "reference", &option_reference, "repo",
  86                     "reference repository", &opt_parse_reference),
  87        OPT_STRING('o', "origin", &option_origin, "name",
  88                   "use <name> instead of 'origin' to track upstream"),
  89        OPT_STRING('b', "branch", &option_branch, "branch",
  90                   "checkout <branch> instead of the remote's HEAD"),
  91        OPT_STRING('u', "upload-pack", &option_upload_pack, "path",
  92                   "path to git-upload-pack on the remote"),
  93        OPT_STRING(0, "depth", &option_depth, "depth",
  94                    "create a shallow clone of that depth"),
  95        OPT_STRING(0, "separate-git-dir", &real_git_dir, "gitdir",
  96                   "separate git dir from working tree"),
  97        OPT_STRING_LIST('c', "config", &option_config, "key=value",
  98                        "set config inside the new repository"),
  99        OPT_END()
 100};
 101
 102static const char *argv_submodule[] = {
 103        "submodule", "update", "--init", "--recursive", NULL
 104};
 105
 106static char *get_repo_path(const char *repo, int *is_bundle)
 107{
 108        static char *suffix[] = { "/.git", ".git", "" };
 109        static char *bundle_suffix[] = { ".bundle", "" };
 110        struct stat st;
 111        int i;
 112
 113        for (i = 0; i < ARRAY_SIZE(suffix); i++) {
 114                const char *path;
 115                path = mkpath("%s%s", repo, suffix[i]);
 116                if (stat(path, &st))
 117                        continue;
 118                if (S_ISDIR(st.st_mode)) {
 119                        *is_bundle = 0;
 120                        return xstrdup(absolute_path(path));
 121                } else if (S_ISREG(st.st_mode) && st.st_size > 8) {
 122                        /* Is it a "gitfile"? */
 123                        char signature[8];
 124                        int len, fd = open(path, O_RDONLY);
 125                        if (fd < 0)
 126                                continue;
 127                        len = read_in_full(fd, signature, 8);
 128                        close(fd);
 129                        if (len != 8 || strncmp(signature, "gitdir: ", 8))
 130                                continue;
 131                        path = read_gitfile(path);
 132                        if (path) {
 133                                *is_bundle = 0;
 134                                return xstrdup(absolute_path(path));
 135                        }
 136                }
 137        }
 138
 139        for (i = 0; i < ARRAY_SIZE(bundle_suffix); i++) {
 140                const char *path;
 141                path = mkpath("%s%s", repo, bundle_suffix[i]);
 142                if (!stat(path, &st) && S_ISREG(st.st_mode)) {
 143                        *is_bundle = 1;
 144                        return xstrdup(absolute_path(path));
 145                }
 146        }
 147
 148        return NULL;
 149}
 150
 151static char *guess_dir_name(const char *repo, int is_bundle, int is_bare)
 152{
 153        const char *end = repo + strlen(repo), *start;
 154        char *dir;
 155
 156        /*
 157         * Strip trailing spaces, slashes and /.git
 158         */
 159        while (repo < end && (is_dir_sep(end[-1]) || isspace(end[-1])))
 160                end--;
 161        if (end - repo > 5 && is_dir_sep(end[-5]) &&
 162            !strncmp(end - 4, ".git", 4)) {
 163                end -= 5;
 164                while (repo < end && is_dir_sep(end[-1]))
 165                        end--;
 166        }
 167
 168        /*
 169         * Find last component, but be prepared that repo could have
 170         * the form  "remote.example.com:foo.git", i.e. no slash
 171         * in the directory part.
 172         */
 173        start = end;
 174        while (repo < start && !is_dir_sep(start[-1]) && start[-1] != ':')
 175                start--;
 176
 177        /*
 178         * Strip .{bundle,git}.
 179         */
 180        if (is_bundle) {
 181                if (end - start > 7 && !strncmp(end - 7, ".bundle", 7))
 182                        end -= 7;
 183        } else {
 184                if (end - start > 4 && !strncmp(end - 4, ".git", 4))
 185                        end -= 4;
 186        }
 187
 188        if (is_bare) {
 189                struct strbuf result = STRBUF_INIT;
 190                strbuf_addf(&result, "%.*s.git", (int)(end - start), start);
 191                dir = strbuf_detach(&result, NULL);
 192        } else
 193                dir = xstrndup(start, end - start);
 194        /*
 195         * Replace sequences of 'control' characters and whitespace
 196         * with one ascii space, remove leading and trailing spaces.
 197         */
 198        if (*dir) {
 199                char *out = dir;
 200                int prev_space = 1 /* strip leading whitespace */;
 201                for (end = dir; *end; ++end) {
 202                        char ch = *end;
 203                        if ((unsigned char)ch < '\x20')
 204                                ch = '\x20';
 205                        if (isspace(ch)) {
 206                                if (prev_space)
 207                                        continue;
 208                                prev_space = 1;
 209                        } else
 210                                prev_space = 0;
 211                        *out++ = ch;
 212                }
 213                *out = '\0';
 214                if (out > dir && prev_space)
 215                        out[-1] = '\0';
 216        }
 217        return dir;
 218}
 219
 220static void strip_trailing_slashes(char *dir)
 221{
 222        char *end = dir + strlen(dir);
 223
 224        while (dir < end - 1 && is_dir_sep(end[-1]))
 225                end--;
 226        *end = '\0';
 227}
 228
 229static int add_one_reference(struct string_list_item *item, void *cb_data)
 230{
 231        char *ref_git;
 232        struct strbuf alternate = STRBUF_INIT;
 233        struct remote *remote;
 234        struct transport *transport;
 235        const struct ref *extra;
 236
 237        /* Beware: real_path() and mkpath() return static buffer */
 238        ref_git = xstrdup(real_path(item->string));
 239        if (is_directory(mkpath("%s/.git/objects", ref_git))) {
 240                char *ref_git_git = xstrdup(mkpath("%s/.git", ref_git));
 241                free(ref_git);
 242                ref_git = ref_git_git;
 243        } else if (!is_directory(mkpath("%s/objects", ref_git)))
 244                die(_("reference repository '%s' is not a local directory."),
 245                    item->string);
 246
 247        strbuf_addf(&alternate, "%s/objects", ref_git);
 248        add_to_alternates_file(alternate.buf);
 249        strbuf_release(&alternate);
 250
 251        remote = remote_get(ref_git);
 252        transport = transport_get(remote, ref_git);
 253        for (extra = transport_get_remote_refs(transport); extra;
 254             extra = extra->next)
 255                add_extra_ref(extra->name, extra->old_sha1, 0);
 256
 257        transport_disconnect(transport);
 258        free(ref_git);
 259        return 0;
 260}
 261
 262static void setup_reference(void)
 263{
 264        for_each_string_list(&option_reference, add_one_reference, NULL);
 265}
 266
 267static void copy_alternates(struct strbuf *src, struct strbuf *dst,
 268                            const char *src_repo)
 269{
 270        /*
 271         * Read from the source objects/info/alternates file
 272         * and copy the entries to corresponding file in the
 273         * destination repository with add_to_alternates_file().
 274         * Both src and dst have "$path/objects/info/alternates".
 275         *
 276         * Instead of copying bit-for-bit from the original,
 277         * we need to append to existing one so that the already
 278         * created entry via "clone -s" is not lost, and also
 279         * to turn entries with paths relative to the original
 280         * absolute, so that they can be used in the new repository.
 281         */
 282        FILE *in = fopen(src->buf, "r");
 283        struct strbuf line = STRBUF_INIT;
 284
 285        while (strbuf_getline(&line, in, '\n') != EOF) {
 286                char *abs_path, abs_buf[PATH_MAX];
 287                if (!line.len || line.buf[0] == '#')
 288                        continue;
 289                if (is_absolute_path(line.buf)) {
 290                        add_to_alternates_file(line.buf);
 291                        continue;
 292                }
 293                abs_path = mkpath("%s/objects/%s", src_repo, line.buf);
 294                normalize_path_copy(abs_buf, abs_path);
 295                add_to_alternates_file(abs_buf);
 296        }
 297        strbuf_release(&line);
 298        fclose(in);
 299}
 300
 301static void copy_or_link_directory(struct strbuf *src, struct strbuf *dest,
 302                                   const char *src_repo, int src_baselen)
 303{
 304        struct dirent *de;
 305        struct stat buf;
 306        int src_len, dest_len;
 307        DIR *dir;
 308
 309        dir = opendir(src->buf);
 310        if (!dir)
 311                die_errno(_("failed to open '%s'"), src->buf);
 312
 313        if (mkdir(dest->buf, 0777)) {
 314                if (errno != EEXIST)
 315                        die_errno(_("failed to create directory '%s'"), dest->buf);
 316                else if (stat(dest->buf, &buf))
 317                        die_errno(_("failed to stat '%s'"), dest->buf);
 318                else if (!S_ISDIR(buf.st_mode))
 319                        die(_("%s exists and is not a directory"), dest->buf);
 320        }
 321
 322        strbuf_addch(src, '/');
 323        src_len = src->len;
 324        strbuf_addch(dest, '/');
 325        dest_len = dest->len;
 326
 327        while ((de = readdir(dir)) != NULL) {
 328                strbuf_setlen(src, src_len);
 329                strbuf_addstr(src, de->d_name);
 330                strbuf_setlen(dest, dest_len);
 331                strbuf_addstr(dest, de->d_name);
 332                if (stat(src->buf, &buf)) {
 333                        warning (_("failed to stat %s\n"), src->buf);
 334                        continue;
 335                }
 336                if (S_ISDIR(buf.st_mode)) {
 337                        if (de->d_name[0] != '.')
 338                                copy_or_link_directory(src, dest,
 339                                                       src_repo, src_baselen);
 340                        continue;
 341                }
 342
 343                /* Files that cannot be copied bit-for-bit... */
 344                if (!strcmp(src->buf + src_baselen, "/info/alternates")) {
 345                        copy_alternates(src, dest, src_repo);
 346                        continue;
 347                }
 348
 349                if (unlink(dest->buf) && errno != ENOENT)
 350                        die_errno(_("failed to unlink '%s'"), dest->buf);
 351                if (!option_no_hardlinks) {
 352                        if (!link(src->buf, dest->buf))
 353                                continue;
 354                        if (option_local)
 355                                die_errno(_("failed to create link '%s'"), dest->buf);
 356                        option_no_hardlinks = 1;
 357                }
 358                if (copy_file_with_time(dest->buf, src->buf, 0666))
 359                        die_errno(_("failed to copy file to '%s'"), dest->buf);
 360        }
 361        closedir(dir);
 362}
 363
 364static const struct ref *clone_local(const char *src_repo,
 365                                     const char *dest_repo)
 366{
 367        const struct ref *ret;
 368        struct remote *remote;
 369        struct transport *transport;
 370
 371        if (option_shared) {
 372                struct strbuf alt = STRBUF_INIT;
 373                strbuf_addf(&alt, "%s/objects", src_repo);
 374                add_to_alternates_file(alt.buf);
 375                strbuf_release(&alt);
 376        } else {
 377                struct strbuf src = STRBUF_INIT;
 378                struct strbuf dest = STRBUF_INIT;
 379                strbuf_addf(&src, "%s/objects", src_repo);
 380                strbuf_addf(&dest, "%s/objects", dest_repo);
 381                copy_or_link_directory(&src, &dest, src_repo, src.len);
 382                strbuf_release(&src);
 383                strbuf_release(&dest);
 384        }
 385
 386        remote = remote_get(src_repo);
 387        transport = transport_get(remote, src_repo);
 388        ret = transport_get_remote_refs(transport);
 389        transport_disconnect(transport);
 390        if (0 <= option_verbosity)
 391                printf(_("done.\n"));
 392        return ret;
 393}
 394
 395static const char *junk_work_tree;
 396static const char *junk_git_dir;
 397static pid_t junk_pid;
 398
 399static void remove_junk(void)
 400{
 401        struct strbuf sb = STRBUF_INIT;
 402        if (getpid() != junk_pid)
 403                return;
 404        if (junk_git_dir) {
 405                strbuf_addstr(&sb, junk_git_dir);
 406                remove_dir_recursively(&sb, 0);
 407                strbuf_reset(&sb);
 408        }
 409        if (junk_work_tree) {
 410                strbuf_addstr(&sb, junk_work_tree);
 411                remove_dir_recursively(&sb, 0);
 412                strbuf_reset(&sb);
 413        }
 414}
 415
 416static void remove_junk_on_signal(int signo)
 417{
 418        remove_junk();
 419        sigchain_pop(signo);
 420        raise(signo);
 421}
 422
 423static struct ref *wanted_peer_refs(const struct ref *refs,
 424                struct refspec *refspec)
 425{
 426        struct ref *head = copy_ref(find_ref_by_name(refs, "HEAD"));
 427        struct ref *local_refs = head;
 428        struct ref **tail = head ? &head->next : &local_refs;
 429
 430        get_fetch_map(refs, refspec, &tail, 0);
 431        if (!option_mirror)
 432                get_fetch_map(refs, tag_refspec, &tail, 0);
 433
 434        return local_refs;
 435}
 436
 437static void write_remote_refs(const struct ref *local_refs)
 438{
 439        const struct ref *r;
 440
 441        for (r = local_refs; r; r = r->next) {
 442                if (!r->peer_ref)
 443                        continue;
 444                add_extra_ref(r->peer_ref->name, r->old_sha1, 0);
 445        }
 446
 447        pack_refs(PACK_REFS_ALL);
 448        clear_extra_refs();
 449}
 450
 451static int write_one_config(const char *key, const char *value, void *data)
 452{
 453        return git_config_set_multivar(key, value ? value : "true", "^$", 0);
 454}
 455
 456static void write_config(struct string_list *config)
 457{
 458        int i;
 459
 460        for (i = 0; i < config->nr; i++) {
 461                if (git_config_parse_parameter(config->items[i].string,
 462                                               write_one_config, NULL) < 0)
 463                        die("unable to write parameters to config file");
 464        }
 465}
 466
 467int cmd_clone(int argc, const char **argv, const char *prefix)
 468{
 469        int is_bundle = 0, is_local;
 470        struct stat buf;
 471        const char *repo_name, *repo, *work_tree, *git_dir;
 472        char *path, *dir;
 473        int dest_exists;
 474        const struct ref *refs, *remote_head;
 475        const struct ref *remote_head_points_at;
 476        const struct ref *our_head_points_at;
 477        struct ref *mapped_refs;
 478        struct strbuf key = STRBUF_INIT, value = STRBUF_INIT;
 479        struct strbuf branch_top = STRBUF_INIT, reflog_msg = STRBUF_INIT;
 480        struct transport *transport = NULL;
 481        char *src_ref_prefix = "refs/heads/";
 482        int err = 0;
 483
 484        struct refspec *refspec;
 485        const char *fetch_pattern;
 486
 487        junk_pid = getpid();
 488
 489        packet_trace_identity("clone");
 490        argc = parse_options(argc, argv, prefix, builtin_clone_options,
 491                             builtin_clone_usage, 0);
 492
 493        if (argc > 2)
 494                usage_msg_opt(_("Too many arguments."),
 495                        builtin_clone_usage, builtin_clone_options);
 496
 497        if (argc == 0)
 498                usage_msg_opt(_("You must specify a repository to clone."),
 499                        builtin_clone_usage, builtin_clone_options);
 500
 501        if (option_mirror)
 502                option_bare = 1;
 503
 504        if (option_bare) {
 505                if (option_origin)
 506                        die(_("--bare and --origin %s options are incompatible."),
 507                            option_origin);
 508                option_no_checkout = 1;
 509        }
 510
 511        if (!option_origin)
 512                option_origin = "origin";
 513
 514        repo_name = argv[0];
 515
 516        path = get_repo_path(repo_name, &is_bundle);
 517        if (path)
 518                repo = xstrdup(absolute_path(repo_name));
 519        else if (!strchr(repo_name, ':'))
 520                die(_("repository '%s' does not exist"), repo_name);
 521        else
 522                repo = repo_name;
 523        is_local = path && !is_bundle;
 524        if (is_local && option_depth)
 525                warning(_("--depth is ignored in local clones; use file:// instead."));
 526
 527        if (argc == 2)
 528                dir = xstrdup(argv[1]);
 529        else
 530                dir = guess_dir_name(repo_name, is_bundle, option_bare);
 531        strip_trailing_slashes(dir);
 532
 533        dest_exists = !stat(dir, &buf);
 534        if (dest_exists && !is_empty_dir(dir))
 535                die(_("destination path '%s' already exists and is not "
 536                        "an empty directory."), dir);
 537
 538        strbuf_addf(&reflog_msg, "clone: from %s", repo);
 539
 540        if (option_bare)
 541                work_tree = NULL;
 542        else {
 543                work_tree = getenv("GIT_WORK_TREE");
 544                if (work_tree && !stat(work_tree, &buf))
 545                        die(_("working tree '%s' already exists."), work_tree);
 546        }
 547
 548        if (option_bare || work_tree)
 549                git_dir = xstrdup(dir);
 550        else {
 551                work_tree = dir;
 552                git_dir = xstrdup(mkpath("%s/.git", dir));
 553        }
 554
 555        if (!option_bare) {
 556                junk_work_tree = work_tree;
 557                if (safe_create_leading_directories_const(work_tree) < 0)
 558                        die_errno(_("could not create leading directories of '%s'"),
 559                                  work_tree);
 560                if (!dest_exists && mkdir(work_tree, 0755))
 561                        die_errno(_("could not create work tree dir '%s'."),
 562                                  work_tree);
 563                set_git_work_tree(work_tree);
 564        }
 565        junk_git_dir = git_dir;
 566        atexit(remove_junk);
 567        sigchain_push_common(remove_junk_on_signal);
 568
 569        setenv(CONFIG_ENVIRONMENT, mkpath("%s/config", git_dir), 1);
 570
 571        if (safe_create_leading_directories_const(git_dir) < 0)
 572                die(_("could not create leading directories of '%s'"), git_dir);
 573
 574        set_git_dir_init(git_dir, real_git_dir, 0);
 575        if (real_git_dir)
 576                git_dir = real_git_dir;
 577
 578        if (0 <= option_verbosity) {
 579                if (option_bare)
 580                        printf(_("Cloning into bare repository '%s'...\n"), dir);
 581                else
 582                        printf(_("Cloning into '%s'...\n"), dir);
 583        }
 584        init_db(option_template, INIT_DB_QUIET);
 585        write_config(&option_config);
 586
 587        /*
 588         * At this point, the config exists, so we do not need the
 589         * environment variable.  We actually need to unset it, too, to
 590         * re-enable parsing of the global configs.
 591         */
 592        unsetenv(CONFIG_ENVIRONMENT);
 593
 594        git_config(git_default_config, NULL);
 595
 596        if (option_bare) {
 597                if (option_mirror)
 598                        src_ref_prefix = "refs/";
 599                strbuf_addstr(&branch_top, src_ref_prefix);
 600
 601                git_config_set("core.bare", "true");
 602        } else {
 603                strbuf_addf(&branch_top, "refs/remotes/%s/", option_origin);
 604        }
 605
 606        strbuf_addf(&value, "+%s*:%s*", src_ref_prefix, branch_top.buf);
 607
 608        if (option_mirror || !option_bare) {
 609                /* Configure the remote */
 610                strbuf_addf(&key, "remote.%s.fetch", option_origin);
 611                git_config_set_multivar(key.buf, value.buf, "^$", 0);
 612                strbuf_reset(&key);
 613
 614                if (option_mirror) {
 615                        strbuf_addf(&key, "remote.%s.mirror", option_origin);
 616                        git_config_set(key.buf, "true");
 617                        strbuf_reset(&key);
 618                }
 619        }
 620
 621        strbuf_addf(&key, "remote.%s.url", option_origin);
 622        git_config_set(key.buf, repo);
 623        strbuf_reset(&key);
 624
 625        if (option_reference.nr)
 626                setup_reference();
 627
 628        fetch_pattern = value.buf;
 629        refspec = parse_fetch_refspec(1, &fetch_pattern);
 630
 631        strbuf_reset(&value);
 632
 633        if (is_local) {
 634                refs = clone_local(path, git_dir);
 635                mapped_refs = wanted_peer_refs(refs, refspec);
 636        } else {
 637                struct remote *remote = remote_get(option_origin);
 638                transport = transport_get(remote, remote->url[0]);
 639
 640                if (!transport->get_refs_list || !transport->fetch)
 641                        die(_("Don't know how to clone %s"), transport->url);
 642
 643                transport_set_option(transport, TRANS_OPT_KEEP, "yes");
 644
 645                if (option_depth)
 646                        transport_set_option(transport, TRANS_OPT_DEPTH,
 647                                             option_depth);
 648
 649                transport_set_verbosity(transport, option_verbosity, option_progress);
 650
 651                if (option_upload_pack)
 652                        transport_set_option(transport, TRANS_OPT_UPLOADPACK,
 653                                             option_upload_pack);
 654
 655                refs = transport_get_remote_refs(transport);
 656                if (refs) {
 657                        mapped_refs = wanted_peer_refs(refs, refspec);
 658                        transport_fetch_refs(transport, mapped_refs);
 659                }
 660        }
 661
 662        if (refs) {
 663                clear_extra_refs();
 664
 665                write_remote_refs(mapped_refs);
 666
 667                remote_head = find_ref_by_name(refs, "HEAD");
 668                remote_head_points_at =
 669                        guess_remote_head(remote_head, mapped_refs, 0);
 670
 671                if (option_branch) {
 672                        struct strbuf head = STRBUF_INIT;
 673                        strbuf_addstr(&head, src_ref_prefix);
 674                        strbuf_addstr(&head, option_branch);
 675                        our_head_points_at =
 676                                find_ref_by_name(mapped_refs, head.buf);
 677                        strbuf_release(&head);
 678
 679                        if (!our_head_points_at) {
 680                                warning(_("Remote branch %s not found in "
 681                                        "upstream %s, using HEAD instead"),
 682                                        option_branch, option_origin);
 683                                our_head_points_at = remote_head_points_at;
 684                        }
 685                }
 686                else
 687                        our_head_points_at = remote_head_points_at;
 688        }
 689        else {
 690                warning(_("You appear to have cloned an empty repository."));
 691                our_head_points_at = NULL;
 692                remote_head_points_at = NULL;
 693                remote_head = NULL;
 694                option_no_checkout = 1;
 695                if (!option_bare)
 696                        install_branch_config(0, "master", option_origin,
 697                                              "refs/heads/master");
 698        }
 699
 700        if (remote_head_points_at && !option_bare) {
 701                struct strbuf head_ref = STRBUF_INIT;
 702                strbuf_addstr(&head_ref, branch_top.buf);
 703                strbuf_addstr(&head_ref, "HEAD");
 704                create_symref(head_ref.buf,
 705                              remote_head_points_at->peer_ref->name,
 706                              reflog_msg.buf);
 707        }
 708
 709        if (our_head_points_at) {
 710                /* Local default branch link */
 711                create_symref("HEAD", our_head_points_at->name, NULL);
 712                if (!option_bare) {
 713                        const char *head = skip_prefix(our_head_points_at->name,
 714                                                       "refs/heads/");
 715                        update_ref(reflog_msg.buf, "HEAD",
 716                                   our_head_points_at->old_sha1,
 717                                   NULL, 0, DIE_ON_ERR);
 718                        install_branch_config(0, head, option_origin,
 719                                              our_head_points_at->name);
 720                }
 721        } else if (remote_head) {
 722                /* Source had detached HEAD pointing somewhere. */
 723                if (!option_bare) {
 724                        update_ref(reflog_msg.buf, "HEAD",
 725                                   remote_head->old_sha1,
 726                                   NULL, REF_NODEREF, DIE_ON_ERR);
 727                        our_head_points_at = remote_head;
 728                }
 729        } else {
 730                /* Nothing to checkout out */
 731                if (!option_no_checkout)
 732                        warning(_("remote HEAD refers to nonexistent ref, "
 733                                "unable to checkout.\n"));
 734                option_no_checkout = 1;
 735        }
 736
 737        if (transport) {
 738                transport_unlock_pack(transport);
 739                transport_disconnect(transport);
 740        }
 741
 742        if (!option_no_checkout) {
 743                struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 744                struct unpack_trees_options opts;
 745                struct tree *tree;
 746                struct tree_desc t;
 747                int fd;
 748
 749                /* We need to be in the new work tree for the checkout */
 750                setup_work_tree();
 751
 752                fd = hold_locked_index(lock_file, 1);
 753
 754                memset(&opts, 0, sizeof opts);
 755                opts.update = 1;
 756                opts.merge = 1;
 757                opts.fn = oneway_merge;
 758                opts.verbose_update = (option_verbosity > 0);
 759                opts.src_index = &the_index;
 760                opts.dst_index = &the_index;
 761
 762                tree = parse_tree_indirect(our_head_points_at->old_sha1);
 763                parse_tree(tree);
 764                init_tree_desc(&t, tree->buffer, tree->size);
 765                unpack_trees(1, &t, &opts);
 766
 767                if (write_cache(fd, active_cache, active_nr) ||
 768                    commit_locked_index(lock_file))
 769                        die(_("unable to write new index file"));
 770
 771                err |= run_hook(NULL, "post-checkout", sha1_to_hex(null_sha1),
 772                                sha1_to_hex(our_head_points_at->old_sha1), "1",
 773                                NULL);
 774
 775                if (!err && option_recursive)
 776                        err = run_command_v_opt(argv_submodule, RUN_GIT_CMD);
 777        }
 778
 779        strbuf_release(&reflog_msg);
 780        strbuf_release(&branch_top);
 781        strbuf_release(&key);
 782        strbuf_release(&value);
 783        junk_pid = 0;
 784        return err;
 785}