git.oblomov.eu Git - git/blob - builtin/init-db.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  */
   6 #include "cache.h"
   7 #include "config.h"
   8 #include "refs.h"
   9 #include "builtin.h"
  10 #include "exec-cmd.h"
  11 #include "parse-options.h"
  12 #include "worktree.h"
  13
  14 #ifndef DEFAULT_GIT_TEMPLATE_DIR
  15 #define DEFAULT_GIT_TEMPLATE_DIR "/usr/share/git-core/templates"
  16 #endif
  17
  18 #ifdef NO_TRUSTABLE_FILEMODE
  19 #define TEST_FILEMODE 0
  20 #else
  21 #define TEST_FILEMODE 1
  22 #endif
  23
  24 #define GIT_DEFAULT_HASH_ENVIRONMENT "GIT_DEFAULT_HASH"
  25
  26 static int init_is_bare_repository = 0;
  27 static int init_shared_repository = -1;
  28
  29 static void copy_templates_1(struct strbuf *path, struct strbuf *template_path,
  30                              DIR *dir)
  31 {
  32         size_t path_baselen = path->len;
  33         size_t template_baselen = template_path->len;
  34         struct dirent *de;
  35
  36         /* Note: if ".git/hooks" file exists in the repository being
  37          * re-initialized, /etc/core-git/templates/hooks/update would
  38          * cause "git init" to fail here.  I think this is sane but
  39          * it means that the set of templates we ship by default, along
  40          * with the way the namespace under .git/ is organized, should
  41          * be really carefully chosen.
  42          */
  43         safe_create_dir(path->buf, 1);
  44         while ((de = readdir(dir)) != NULL) {
  45                 struct stat st_git, st_template;
  46                 int exists = 0;
  47
  48                 strbuf_setlen(path, path_baselen);
  49                 strbuf_setlen(template_path, template_baselen);
  50
  51                 if (de->d_name[0] == '.')
  52                         continue;
  53                 strbuf_addstr(path, de->d_name);
  54                 strbuf_addstr(template_path, de->d_name);
  55                 if (lstat(path->buf, &st_git)) {
  56                         if (errno != ENOENT)
  57                                 die_errno(_("cannot stat '%s'"), path->buf);
  58                 }
  59                 else
  60                         exists = 1;
  61
  62                 if (lstat(template_path->buf, &st_template))
  63                         die_errno(_("cannot stat template '%s'"), template_path->buf);
  64
  65                 if (S_ISDIR(st_template.st_mode)) {
  66                         DIR *subdir = opendir(template_path->buf);
  67                         if (!subdir)
  68                                 die_errno(_("cannot opendir '%s'"), template_path->buf);
  69                         strbuf_addch(path, '/');
  70                         strbuf_addch(template_path, '/');
  71                         copy_templates_1(path, template_path, subdir);
  72                         closedir(subdir);
  73                 }
  74                 else if (exists)
  75                         continue;
  76                 else if (S_ISLNK(st_template.st_mode)) {
  77                         struct strbuf lnk = STRBUF_INIT;
  78                         if (strbuf_readlink(&lnk, template_path->buf,
  79                                             st_template.st_size) < 0)
  80                                 die_errno(_("cannot readlink '%s'"), template_path->buf);
  81                         if (symlink(lnk.buf, path->buf))
  82                                 die_errno(_("cannot symlink '%s' '%s'"),
  83                                           lnk.buf, path->buf);
  84                         strbuf_release(&lnk);
  85                 }
  86                 else if (S_ISREG(st_template.st_mode)) {
  87                         if (copy_file(path->buf, template_path->buf, st_template.st_mode))
  88                                 die_errno(_("cannot copy '%s' to '%s'"),
  89                                           template_path->buf, path->buf);
  90                 }
  91                 else
  92                         error(_("ignoring template %s"), template_path->buf);
  93         }
  94 }
  95
  96 static void copy_templates(const char *template_dir, const char *init_template_dir)
  97 {
  98         struct strbuf path = STRBUF_INIT;
  99         struct strbuf template_path = STRBUF_INIT;
 100         size_t template_len;
 101         struct repository_format template_format = REPOSITORY_FORMAT_INIT;
 102         struct strbuf err = STRBUF_INIT;
 103         DIR *dir;
 104         char *to_free = NULL;
 105
 106         if (!template_dir)
 107                 template_dir = getenv(TEMPLATE_DIR_ENVIRONMENT);
 108         if (!template_dir)
 109                 template_dir = init_template_dir;
 110         if (!template_dir)
 111                 template_dir = to_free = system_path(DEFAULT_GIT_TEMPLATE_DIR);
 112         if (!template_dir[0]) {
 113                 free(to_free);
 114                 return;
 115         }
 116
 117         strbuf_addstr(&template_path, template_dir);
 118         strbuf_complete(&template_path, '/');
 119         template_len = template_path.len;
 120
 121         dir = opendir(template_path.buf);
 122         if (!dir) {
 123                 warning(_("templates not found in %s"), template_dir);
 124                 goto free_return;
 125         }
 126
 127         /* Make sure that template is from the correct vintage */
 128         strbuf_addstr(&template_path, "config");
 129         read_repository_format(&template_format, template_path.buf);
 130         strbuf_setlen(&template_path, template_len);
 131
 132         /*
 133          * No mention of version at all is OK, but anything else should be
 134          * verified.
 135          */
 136         if (template_format.version >= 0 &&
 137             verify_repository_format(&template_format, &err) < 0) {
 138                 warning(_("not copying templates from '%s': %s"),
 139                           template_dir, err.buf);
 140                 strbuf_release(&err);
 141                 goto close_free_return;
 142         }
 143
 144         strbuf_addstr(&path, get_git_common_dir());
 145         strbuf_complete(&path, '/');
 146         copy_templates_1(&path, &template_path, dir);
 147 close_free_return:
 148         closedir(dir);
 149 free_return:
 150         free(to_free);
 151         strbuf_release(&path);
 152         strbuf_release(&template_path);
 153         clear_repository_format(&template_format);
 154 }
 155
 156 /*
 157  * If the git_dir is not directly inside the working tree, then git will not
 158  * find it by default, and we need to set the worktree explicitly.
 159  */
 160 static int needs_work_tree_config(const char *git_dir, const char *work_tree)
 161 {
 162         if (!strcmp(work_tree, "/") && !strcmp(git_dir, "/.git"))
 163                 return 0;
 164         if (skip_prefix(git_dir, work_tree, &git_dir) &&
 165             !strcmp(git_dir, "/.git"))
 166                 return 0;
 167         return 1;
 168 }
 169
 170 void initialize_repository_version(int hash_algo, int reinit)
 171 {
 172         char repo_version_string[10];
 173         int repo_version = GIT_REPO_VERSION;
 174
 175         if (hash_algo != GIT_HASH_SHA1)
 176                 repo_version = GIT_REPO_VERSION_READ;
 177
 178         /* This forces creation of new config file */
 179         xsnprintf(repo_version_string, sizeof(repo_version_string),
 180                   "%d", repo_version);
 181         git_config_set("core.repositoryformatversion", repo_version_string);
 182
 183         if (hash_algo != GIT_HASH_SHA1)
 184                 git_config_set("extensions.objectformat",
 185                                hash_algos[hash_algo].name);
 186         else if (reinit)
 187                 git_config_set_gently("extensions.objectformat", NULL);
 188 }
 189
 190 static int create_default_files(const char *template_path,
 191                                 const char *original_git_dir,
 192                                 const char *initial_branch,
 193                                 const struct repository_format *fmt,
 194                                 int quiet)
 195 {
 196         struct stat st1;
 197         struct strbuf buf = STRBUF_INIT;
 198         char *path;
 199         char junk[2];
 200         int reinit;
 201         int filemode;
 202         struct strbuf err = STRBUF_INIT;
 203         const char *init_template_dir = NULL;
 204         const char *work_tree = get_git_work_tree();
 205
 206         /*
 207          * First copy the templates -- we might have the default
 208          * config file there, in which case we would want to read
 209          * from it after installing.
 210          *
 211          * Before reading that config, we also need to clear out any cached
 212          * values (since we've just potentially changed what's available on
 213          * disk).
 214          */
 215         git_config_get_pathname("init.templatedir", &init_template_dir);
 216         copy_templates(template_path, init_template_dir);
 217         free((char *)init_template_dir);
 218         git_config_clear();
 219         reset_shared_repository();
 220         git_config(git_default_config, NULL);
 221
 222         /*
 223          * We must make sure command-line options continue to override any
 224          * values we might have just re-read from the config.
 225          */
 226         is_bare_repository_cfg = init_is_bare_repository || !work_tree;
 227         if (init_shared_repository != -1)
 228                 set_shared_repository(init_shared_repository);
 229
 230         /*
 231          * We would have created the above under user's umask -- under
 232          * shared-repository settings, we would need to fix them up.
 233          */
 234         if (get_shared_repository()) {
 235                 adjust_shared_perm(get_git_dir());
 236         }
 237
 238         /*
 239          * We need to create a "refs" dir in any case so that older
 240          * versions of git can tell that this is a repository.
 241          */
 242         safe_create_dir(git_path("refs"), 1);
 243         adjust_shared_perm(git_path("refs"));
 244
 245         if (refs_init_db(&err))
 246                 die("failed to set up refs db: %s", err.buf);
 247
 248         /*
 249          * Point the HEAD symref to the initial branch with if HEAD does
 250          * not yet exist.
 251          */
 252         path = git_path_buf(&buf, "HEAD");
 253         reinit = (!access(path, R_OK)
 254                   || readlink(path, junk, sizeof(junk)-1) != -1);
 255         if (!reinit) {
 256                 char *ref;
 257
 258                 if (!initial_branch)
 259                         initial_branch = git_default_branch_name(quiet);
 260
 261                 ref = xstrfmt("refs/heads/%s", initial_branch);
 262                 if (check_refname_format(ref, 0) < 0)
 263                         die(_("invalid initial branch name: '%s'"),
 264                             initial_branch);
 265
 266                 if (create_symref("HEAD", ref, NULL) < 0)
 267                         exit(1);
 268                 free(ref);
 269         }
 270
 271         initialize_repository_version(fmt->hash_algo, 0);
 272
 273         /* Check filemode trustability */
 274         path = git_path_buf(&buf, "config");
 275         filemode = TEST_FILEMODE;
 276         if (TEST_FILEMODE && !lstat(path, &st1)) {
 277                 struct stat st2;
 278                 filemode = (!chmod(path, st1.st_mode ^ S_IXUSR) &&
 279                                 !lstat(path, &st2) &&
 280                                 st1.st_mode != st2.st_mode &&
 281                                 !chmod(path, st1.st_mode));
 282                 if (filemode && !reinit && (st1.st_mode & S_IXUSR))
 283                         filemode = 0;
 284         }
 285         git_config_set("core.filemode", filemode ? "true" : "false");
 286
 287         if (is_bare_repository())
 288                 git_config_set("core.bare", "true");
 289         else {
 290                 git_config_set("core.bare", "false");
 291                 /* allow template config file to override the default */
 292                 if (log_all_ref_updates == LOG_REFS_UNSET)
 293                         git_config_set("core.logallrefupdates", "true");
 294                 if (needs_work_tree_config(original_git_dir, work_tree))
 295                         git_config_set("core.worktree", work_tree);
 296         }
 297
 298         if (!reinit) {
 299                 /* Check if symlink is supported in the work tree */
 300                 path = git_path_buf(&buf, "tXXXXXX");
 301                 if (!close(xmkstemp(path)) &&
 302                     !unlink(path) &&
 303                     !symlink("testing", path) &&
 304                     !lstat(path, &st1) &&
 305                     S_ISLNK(st1.st_mode))
 306                         unlink(path); /* good */
 307                 else
 308                         git_config_set("core.symlinks", "false");
 309
 310                 /* Check if the filesystem is case-insensitive */
 311                 path = git_path_buf(&buf, "CoNfIg");
 312                 if (!access(path, F_OK))
 313                         git_config_set("core.ignorecase", "true");
 314                 probe_utf8_pathname_composition();
 315         }
 316
 317         strbuf_release(&buf);
 318         return reinit;
 319 }
 320
 321 static void create_object_directory(void)
 322 {
 323         struct strbuf path = STRBUF_INIT;
 324         size_t baselen;
 325
 326         strbuf_addstr(&path, get_object_directory());
 327         baselen = path.len;
 328
 329         safe_create_dir(path.buf, 1);
 330
 331         strbuf_setlen(&path, baselen);
 332         strbuf_addstr(&path, "/pack");
 333         safe_create_dir(path.buf, 1);
 334
 335         strbuf_setlen(&path, baselen);
 336         strbuf_addstr(&path, "/info");
 337         safe_create_dir(path.buf, 1);
 338
 339         strbuf_release(&path);
 340 }
 341
 342 static void separate_git_dir(const char *git_dir, const char *git_link)
 343 {
 344         struct stat st;
 345
 346         if (!stat(git_link, &st)) {
 347                 const char *src;
 348
 349                 if (S_ISREG(st.st_mode))
 350                         src = read_gitfile(git_link);
 351                 else if (S_ISDIR(st.st_mode))
 352                         src = git_link;
 353                 else
 354                         die(_("unable to handle file type %d"), (int)st.st_mode);
 355
 356                 if (rename(src, git_dir))
 357                         die_errno(_("unable to move %s to %s"), src, git_dir);
 358                 repair_worktrees(NULL, NULL);
 359         }
 360
 361         write_file(git_link, "gitdir: %s", git_dir);
 362 }
 363
 364 static void validate_hash_algorithm(struct repository_format *repo_fmt, int hash)
 365 {
 366         const char *env = getenv(GIT_DEFAULT_HASH_ENVIRONMENT);
 367         /*
 368          * If we already have an initialized repo, don't allow the user to
 369          * specify a different algorithm, as that could cause corruption.
 370          * Otherwise, if the user has specified one on the command line, use it.
 371          */
 372         if (repo_fmt->version >= 0 && hash != GIT_HASH_UNKNOWN && hash != repo_fmt->hash_algo)
 373                 die(_("attempt to reinitialize repository with different hash"));
 374         else if (hash != GIT_HASH_UNKNOWN)
 375                 repo_fmt->hash_algo = hash;
 376         else if (env) {
 377                 int env_algo = hash_algo_by_name(env);
 378                 if (env_algo == GIT_HASH_UNKNOWN)
 379                         die(_("unknown hash algorithm '%s'"), env);
 380                 repo_fmt->hash_algo = env_algo;
 381         }
 382 }
 383
 384 int init_db(const char *git_dir, const char *real_git_dir,
 385             const char *template_dir, int hash, const char *initial_branch,
 386             unsigned int flags)
 387 {
 388         int reinit;
 389         int exist_ok = flags & INIT_DB_EXIST_OK;
 390         char *original_git_dir = real_pathdup(git_dir, 1);
 391         struct repository_format repo_fmt = REPOSITORY_FORMAT_INIT;
 392
 393         if (real_git_dir) {
 394                 struct stat st;
 395
 396                 if (!exist_ok && !stat(git_dir, &st))
 397                         die(_("%s already exists"), git_dir);
 398
 399                 if (!exist_ok && !stat(real_git_dir, &st))
 400                         die(_("%s already exists"), real_git_dir);
 401
 402                 set_git_dir(real_git_dir, 1);
 403                 git_dir = get_git_dir();
 404                 separate_git_dir(git_dir, original_git_dir);
 405         }
 406         else {
 407                 set_git_dir(git_dir, 1);
 408                 git_dir = get_git_dir();
 409         }
 410         startup_info->have_repository = 1;
 411
 412         /* Ensure `core.hidedotfiles` is processed */
 413         git_config(platform_core_config, NULL);
 414
 415         safe_create_dir(git_dir, 0);
 416
 417         init_is_bare_repository = is_bare_repository();
 418
 419         /* Check to see if the repository version is right.
 420          * Note that a newly created repository does not have
 421          * config file, so this will not fail.  What we are catching
 422          * is an attempt to reinitialize new repository with an old tool.
 423          */
 424         check_repository_format(&repo_fmt);
 425
 426         validate_hash_algorithm(&repo_fmt, hash);
 427
 428         reinit = create_default_files(template_dir, original_git_dir,
 429                                       initial_branch, &repo_fmt,
 430                                       flags & INIT_DB_QUIET);
 431         if (reinit && initial_branch)
 432                 warning(_("re-init: ignored --initial-branch=%s"),
 433                         initial_branch);
 434
 435         create_object_directory();
 436
 437         if (get_shared_repository()) {
 438                 char buf[10];
 439                 /* We do not spell "group" and such, so that
 440                  * the configuration can be read by older version
 441                  * of git. Note, we use octal numbers for new share modes,
 442                  * and compatibility values for PERM_GROUP and
 443                  * PERM_EVERYBODY.
 444                  */
 445                 if (get_shared_repository() < 0)
 446                         /* force to the mode value */
 447                         xsnprintf(buf, sizeof(buf), "0%o", -get_shared_repository());
 448                 else if (get_shared_repository() == PERM_GROUP)
 449                         xsnprintf(buf, sizeof(buf), "%d", OLD_PERM_GROUP);
 450                 else if (get_shared_repository() == PERM_EVERYBODY)
 451                         xsnprintf(buf, sizeof(buf), "%d", OLD_PERM_EVERYBODY);
 452                 else
 453                         BUG("invalid value for shared_repository");
 454                 git_config_set("core.sharedrepository", buf);
 455                 git_config_set("receive.denyNonFastforwards", "true");
 456         }
 457
 458         if (!(flags & INIT_DB_QUIET)) {
 459                 int len = strlen(git_dir);
 460
 461                 if (reinit)
 462                         printf(get_shared_repository()
 463                                ? _("Reinitialized existing shared Git repository in %s%s\n")
 464                                : _("Reinitialized existing Git repository in %s%s\n"),
 465                                git_dir, len && git_dir[len-1] != '/' ? "/" : "");
 466                 else
 467                         printf(get_shared_repository()
 468                                ? _("Initialized empty shared Git repository in %s%s\n")
 469                                : _("Initialized empty Git repository in %s%s\n"),
 470                                git_dir, len && git_dir[len-1] != '/' ? "/" : "");
 471         }
 472
 473         free(original_git_dir);
 474         return 0;
 475 }
 476
 477 static int guess_repository_type(const char *git_dir)
 478 {
 479         const char *slash;
 480         char *cwd;
 481         int cwd_is_git_dir;
 482
 483         /*
 484          * "GIT_DIR=. git init" is always bare.
 485          * "GIT_DIR=`pwd` git init" too.
 486          */
 487         if (!strcmp(".", git_dir))
 488                 return 1;
 489         cwd = xgetcwd();
 490         cwd_is_git_dir = !strcmp(git_dir, cwd);
 491         free(cwd);
 492         if (cwd_is_git_dir)
 493                 return 1;
 494         /*
 495          * "GIT_DIR=.git or GIT_DIR=something/.git is usually not.
 496          */
 497         if (!strcmp(git_dir, ".git"))
 498                 return 0;
 499         slash = strrchr(git_dir, '/');
 500         if (slash && !strcmp(slash, "/.git"))
 501                 return 0;
 502
 503         /*
 504          * Otherwise it is often bare.  At this point
 505          * we are just guessing.
 506          */
 507         return 1;
 508 }
 509
 510 static int shared_callback(const struct option *opt, const char *arg, int unset)
 511 {
 512         BUG_ON_OPT_NEG(unset);
 513         *((int *) opt->value) = (arg) ? git_config_perm("arg", arg) : PERM_GROUP;
 514         return 0;
 515 }
 516
 517 static const char *const init_db_usage[] = {
 518         N_("git init [-q | --quiet] [--bare] [--template=<template-directory>] [--shared[=<permissions>]] [<directory>]"),
 519         NULL
 520 };
 521
 522 /*
 523  * If you want to, you can share the DB area with any number of branches.
 524  * That has advantages: you can save space by sharing all the SHA1 objects.
 525  * On the other hand, it might just make lookup slower and messier. You
 526  * be the judge.  The default case is to have one DB per managed directory.
 527  */
 528 int cmd_init_db(int argc, const char **argv, const char *prefix)
 529 {
 530         const char *git_dir;
 531         const char *real_git_dir = NULL;
 532         const char *work_tree;
 533         const char *template_dir = NULL;
 534         unsigned int flags = 0;
 535         const char *object_format = NULL;
 536         const char *initial_branch = NULL;
 537         int hash_algo = GIT_HASH_UNKNOWN;
 538         const struct option init_db_options[] = {
 539                 OPT_STRING(0, "template", &template_dir, N_("template-directory"),
 540                                 N_("directory from which templates will be used")),
 541                 OPT_SET_INT(0, "bare", &is_bare_repository_cfg,
 542                                 N_("create a bare repository"), 1),
 543                 { OPTION_CALLBACK, 0, "shared", &init_shared_repository,
 544                         N_("permissions"),
 545                         N_("specify that the git repository is to be shared amongst several users"),
 546                         PARSE_OPT_OPTARG | PARSE_OPT_NONEG, shared_callback, 0},
 547                 OPT_BIT('q', "quiet", &flags, N_("be quiet"), INIT_DB_QUIET),
 548                 OPT_STRING(0, "separate-git-dir", &real_git_dir, N_("gitdir"),
 549                            N_("separate git dir from working tree")),
 550                 OPT_STRING('b', "initial-branch", &initial_branch, N_("name"),
 551                            N_("override the name of the initial branch")),
 552                 OPT_STRING(0, "object-format", &object_format, N_("hash"),
 553                            N_("specify the hash algorithm to use")),
 554                 OPT_END()
 555         };
 556
 557         argc = parse_options(argc, argv, prefix, init_db_options, init_db_usage, 0);
 558
 559         if (real_git_dir && is_bare_repository_cfg == 1)
 560                 die(_("--separate-git-dir and --bare are mutually exclusive"));
 561
 562         if (real_git_dir && !is_absolute_path(real_git_dir))
 563                 real_git_dir = real_pathdup(real_git_dir, 1);
 564
 565         if (template_dir && *template_dir && !is_absolute_path(template_dir)) {
 566                 template_dir = absolute_pathdup(template_dir);
 567                 UNLEAK(template_dir);
 568         }
 569
 570         if (argc == 1) {
 571                 int mkdir_tried = 0;
 572         retry:
 573                 if (chdir(argv[0]) < 0) {
 574                         if (!mkdir_tried) {
 575                                 int saved;
 576                                 /*
 577                                  * At this point we haven't read any configuration,
 578                                  * and we know shared_repository should always be 0;
 579                                  * but just in case we play safe.
 580                                  */
 581                                 saved = get_shared_repository();
 582                                 set_shared_repository(0);
 583                                 switch (safe_create_leading_directories_const(argv[0])) {
 584                                 case SCLD_OK:
 585                                 case SCLD_PERMS:
 586                                         break;
 587                                 case SCLD_EXISTS:
 588                                         errno = EEXIST;
 589                                         /* fallthru */
 590                                 default:
 591                                         die_errno(_("cannot mkdir %s"), argv[0]);
 592                                         break;
 593                                 }
 594                                 set_shared_repository(saved);
 595                                 if (mkdir(argv[0], 0777) < 0)
 596                                         die_errno(_("cannot mkdir %s"), argv[0]);
 597                                 mkdir_tried = 1;
 598                                 goto retry;
 599                         }
 600                         die_errno(_("cannot chdir to %s"), argv[0]);
 601                 }
 602         } else if (0 < argc) {
 603                 usage(init_db_usage[0]);
 604         }
 605         if (is_bare_repository_cfg == 1) {
 606                 char *cwd = xgetcwd();
 607                 setenv(GIT_DIR_ENVIRONMENT, cwd, argc > 0);
 608                 free(cwd);
 609         }
 610
 611         if (object_format) {
 612                 hash_algo = hash_algo_by_name(object_format);
 613                 if (hash_algo == GIT_HASH_UNKNOWN)
 614                         die(_("unknown hash algorithm '%s'"), object_format);
 615         }
 616
 617         if (init_shared_repository != -1)
 618                 set_shared_repository(init_shared_repository);
 619
 620         /*
 621          * GIT_WORK_TREE makes sense only in conjunction with GIT_DIR
 622          * without --bare.  Catch the error early.
 623          */
 624         git_dir = xstrdup_or_null(getenv(GIT_DIR_ENVIRONMENT));
 625         work_tree = xstrdup_or_null(getenv(GIT_WORK_TREE_ENVIRONMENT));
 626         if ((!git_dir || is_bare_repository_cfg == 1) && work_tree)
 627                 die(_("%s (or --work-tree=<directory>) not allowed without "
 628                           "specifying %s (or --git-dir=<directory>)"),
 629                     GIT_WORK_TREE_ENVIRONMENT,
 630                     GIT_DIR_ENVIRONMENT);
 631
 632         /*
 633          * Set up the default .git directory contents
 634          */
 635         if (!git_dir)
 636                 git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
 637
 638         /*
 639          * When --separate-git-dir is used inside a linked worktree, take
 640          * care to ensure that the common .git/ directory is relocated, not
 641          * the worktree-specific .git/worktrees/<id>/ directory.
 642          */
 643         if (real_git_dir) {
 644                 int err;
 645                 const char *p;
 646                 struct strbuf sb = STRBUF_INIT;
 647
 648                 p = read_gitfile_gently(git_dir, &err);
 649                 if (p && get_common_dir(&sb, p)) {
 650                         struct strbuf mainwt = STRBUF_INIT;
 651
 652                         strbuf_addbuf(&mainwt, &sb);
 653                         strbuf_strip_suffix(&mainwt, "/.git");
 654                         if (chdir(mainwt.buf) < 0)
 655                                 die_errno(_("cannot chdir to %s"), mainwt.buf);
 656                         strbuf_release(&mainwt);
 657                         git_dir = strbuf_detach(&sb, NULL);
 658                 }
 659                 strbuf_release(&sb);
 660         }
 661
 662         if (is_bare_repository_cfg < 0)
 663                 is_bare_repository_cfg = guess_repository_type(git_dir);
 664
 665         if (!is_bare_repository_cfg) {
 666                 const char *git_dir_parent = strrchr(git_dir, '/');
 667                 if (git_dir_parent) {
 668                         char *rel = xstrndup(git_dir, git_dir_parent - git_dir);
 669                         git_work_tree_cfg = real_pathdup(rel, 1);
 670                         free(rel);
 671                 }
 672                 if (!git_work_tree_cfg)
 673                         git_work_tree_cfg = xgetcwd();
 674                 if (work_tree)
 675                         set_git_work_tree(work_tree);
 676                 else
 677                         set_git_work_tree(git_work_tree_cfg);
 678                 if (access(get_git_work_tree(), X_OK))
 679                         die_errno (_("Cannot access work tree '%s'"),
 680                                    get_git_work_tree());
 681         }
 682         else {
 683                 if (real_git_dir)
 684                         die(_("--separate-git-dir incompatible with bare repository"));
 685                 if (work_tree)
 686                         set_git_work_tree(work_tree);
 687         }
 688
 689         UNLEAK(real_git_dir);
 690         UNLEAK(git_dir);
 691         UNLEAK(work_tree);
 692
 693         flags |= INIT_DB_EXIST_OK;
 694         return init_db(git_dir, real_git_dir, template_dir, hash_algo,
 695                        initial_branch, flags);
 696 }