setup.c

   1 #include "cache.h"
   2 #include "dir.h"
   3 #include "string-list.h"
   4
   5 static int inside_git_dir = -1;
   6 static int inside_work_tree = -1;
   7
   8 static char *prefix_path_gently(const char *prefix, int len, const char *path)
   9 {
  10         const char *orig = path;
  11         char *sanitized;
  12         if (is_absolute_path(orig)) {
  13                 const char *temp = real_path(path);
  14                 sanitized = xmalloc(len + strlen(temp) + 1);
  15                 strcpy(sanitized, temp);
  16         } else {
  17                 sanitized = xmalloc(len + strlen(path) + 1);
  18                 if (len)
  19                         memcpy(sanitized, prefix, len);
  20                 strcpy(sanitized + len, path);
  21         }
  22         if (normalize_path_copy(sanitized, sanitized))
  23                 goto error_out;
  24         if (is_absolute_path(orig)) {
  25                 size_t root_len, len, total;
  26                 const char *work_tree = get_git_work_tree();
  27                 if (!work_tree)
  28                         goto error_out;
  29                 len = strlen(work_tree);
  30                 root_len = offset_1st_component(work_tree);
  31                 total = strlen(sanitized) + 1;
  32                 if (strncmp(sanitized, work_tree, len) ||
  33                     (len > root_len && sanitized[len] != '\0' && sanitized[len] != '/')) {
  34                 error_out:
  35                         free(sanitized);
  36                         return NULL;
  37                 }
  38                 if (sanitized[len] == '/')
  39                         len++;
  40                 memmove(sanitized, sanitized + len, total - len);
  41         }
  42         return sanitized;
  43 }
  44
  45 char *prefix_path(const char *prefix, int len, const char *path)
  46 {
  47         char *r = prefix_path_gently(prefix, len, path);
  48         if (!r)
  49                 die("'%s' is outside repository", path);
  50         return r;
  51 }
  52
  53 int path_inside_repo(const char *prefix, const char *path)
  54 {
  55         int len = prefix ? strlen(prefix) : 0;
  56         char *r = prefix_path_gently(prefix, len, path);
  57         if (r) {
  58                 free(r);
  59                 return 1;
  60         }
  61         return 0;
  62 }
  63
  64 int check_filename(const char *prefix, const char *arg)
  65 {
  66         const char *name;
  67         struct stat st;
  68
  69         name = prefix ? prefix_filename(prefix, strlen(prefix), arg) : arg;
  70         if (!lstat(name, &st))
  71                 return 1; /* file exists */
  72         if (errno == ENOENT || errno == ENOTDIR)
  73                 return 0; /* file does not exist */
  74         die_errno("failed to stat '%s'", arg);
  75 }
  76
  77 static void NORETURN die_verify_filename(const char *prefix,
  78                                          const char *arg,
  79                                          int diagnose_misspelt_rev)
  80 {
  81         if (!diagnose_misspelt_rev)
  82                 die("%s: no such path in the working tree.\n"
  83                     "Use 'git <command> -- <path>...' to specify paths that do not exist locally.",
  84                     arg);
  85         /*
  86          * Saying "'(icase)foo' does not exist in the index" when the
  87          * user gave us ":(icase)foo" is just stupid.  A magic pathspec
  88          * begins with a colon and is followed by a non-alnum; do not
  89          * let maybe_die_on_misspelt_object_name() even trigger.
  90          */
  91         if (!(arg[0] == ':' && !isalnum(arg[1])))
  92                 maybe_die_on_misspelt_object_name(arg, prefix);
  93
  94         /* ... or fall back the most general message. */
  95         die("ambiguous argument '%s': unknown revision or path not in the working tree.\n"
  96             "Use '--' to separate paths from revisions, like this:\n"
  97             "'git <command> [<revision>...] -- [<file>...]'", arg);
  98
  99 }
 100
 101 /*
 102  * Verify a filename that we got as an argument for a pathspec
 103  * entry. Note that a filename that begins with "-" never verifies
 104  * as true, because even if such a filename were to exist, we want
 105  * it to be preceded by the "--" marker (or we want the user to
 106  * use a format like "./-filename")
 107  *
 108  * The "diagnose_misspelt_rev" is used to provide a user-friendly
 109  * diagnosis when dying upon finding that "name" is not a pathname.
 110  * If set to 1, the diagnosis will try to diagnose "name" as an
 111  * invalid object name (e.g. HEAD:foo). If set to 0, the diagnosis
 112  * will only complain about an inexisting file.
 113  *
 114  * This function is typically called to check that a "file or rev"
 115  * argument is unambiguous. In this case, the caller will want
 116  * diagnose_misspelt_rev == 1 when verifying the first non-rev
 117  * argument (which could have been a revision), and
 118  * diagnose_misspelt_rev == 0 for the next ones (because we already
 119  * saw a filename, there's not ambiguity anymore).
 120  */
 121 void verify_filename(const char *prefix,
 122                      const char *arg,
 123                      int diagnose_misspelt_rev)
 124 {
 125         if (*arg == '-')
 126                 die("bad flag '%s' used after filename", arg);
 127         if (check_filename(prefix, arg))
 128                 return;
 129         die_verify_filename(prefix, arg, diagnose_misspelt_rev);
 130 }
 131
 132 /*
 133  * Opposite of the above: the command line did not have -- marker
 134  * and we parsed the arg as a refname.  It should not be interpretable
 135  * as a filename.
 136  */
 137 void verify_non_filename(const char *prefix, const char *arg)
 138 {
 139         if (!is_inside_work_tree() || is_inside_git_dir())
 140                 return;
 141         if (*arg == '-')
 142                 return; /* flag */
 143         if (!check_filename(prefix, arg))
 144                 return;
 145         die("ambiguous argument '%s': both revision and filename\n"
 146             "Use '--' to separate paths from revisions, like this:\n"
 147             "'git <command> [<revision>...] -- [<file>...]'", arg);
 148 }
 149
 150 /*
 151  * Magic pathspec
 152  *
 153  * NEEDSWORK: These need to be moved to dir.h or even to a new
 154  * pathspec.h when we restructure get_pathspec() users to use the
 155  * "struct pathspec" interface.
 156  *
 157  * Possible future magic semantics include stuff like:
 158  *
 159  *      { PATHSPEC_NOGLOB, '!', "noglob" },
 160  *      { PATHSPEC_ICASE, '\0', "icase" },
 161  *      { PATHSPEC_RECURSIVE, '*', "recursive" },
 162  *      { PATHSPEC_REGEXP, '\0', "regexp" },
 163  *
 164  */
 165 #define PATHSPEC_FROMTOP    (1<<0)
 166
 167 static struct pathspec_magic {
 168         unsigned bit;
 169         char mnemonic; /* this cannot be ':'! */
 170         const char *name;
 171 } pathspec_magic[] = {
 172         { PATHSPEC_FROMTOP, '/', "top" },
 173 };
 174
 175 /*
 176  * Take an element of a pathspec and check for magic signatures.
 177  * Append the result to the prefix.
 178  *
 179  * For now, we only parse the syntax and throw out anything other than
 180  * "top" magic.
 181  *
 182  * NEEDSWORK: This needs to be rewritten when we start migrating
 183  * get_pathspec() users to use the "struct pathspec" interface.  For
 184  * example, a pathspec element may be marked as case-insensitive, but
 185  * the prefix part must always match literally, and a single stupid
 186  * string cannot express such a case.
 187  */
 188 static const char *prefix_pathspec(const char *prefix, int prefixlen, const char *elt)
 189 {
 190         unsigned magic = 0;
 191         const char *copyfrom = elt;
 192         int i;
 193
 194         if (elt[0] != ':') {
 195                 ; /* nothing to do */
 196         } else if (elt[1] == '(') {
 197                 /* longhand */
 198                 const char *nextat;
 199                 for (copyfrom = elt + 2;
 200                      *copyfrom && *copyfrom != ')';
 201                      copyfrom = nextat) {
 202                         size_t len = strcspn(copyfrom, ",)");
 203                         if (copyfrom[len] == ')')
 204                                 nextat = copyfrom + len;
 205                         else
 206                                 nextat = copyfrom + len + 1;
 207                         if (!len)
 208                                 continue;
 209                         for (i = 0; i < ARRAY_SIZE(pathspec_magic); i++)
 210                                 if (strlen(pathspec_magic[i].name) == len &&
 211                                     !strncmp(pathspec_magic[i].name, copyfrom, len)) {
 212                                         magic |= pathspec_magic[i].bit;
 213                                         break;
 214                                 }
 215                         if (ARRAY_SIZE(pathspec_magic) <= i)
 216                                 die("Invalid pathspec magic '%.*s' in '%s'",
 217                                     (int) len, copyfrom, elt);
 218                 }
 219                 if (*copyfrom == ')')
 220                         copyfrom++;
 221         } else {
 222                 /* shorthand */
 223                 for (copyfrom = elt + 1;
 224                      *copyfrom && *copyfrom != ':';
 225                      copyfrom++) {
 226                         char ch = *copyfrom;
 227
 228                         if (!is_pathspec_magic(ch))
 229                                 break;
 230                         for (i = 0; i < ARRAY_SIZE(pathspec_magic); i++)
 231                                 if (pathspec_magic[i].mnemonic == ch) {
 232                                         magic |= pathspec_magic[i].bit;
 233                                         break;
 234                                 }
 235                         if (ARRAY_SIZE(pathspec_magic) <= i)
 236                                 die("Unimplemented pathspec magic '%c' in '%s'",
 237                                     ch, elt);
 238                 }
 239                 if (*copyfrom == ':')
 240                         copyfrom++;
 241         }
 242
 243         if (magic & PATHSPEC_FROMTOP)
 244                 return xstrdup(copyfrom);
 245         else
 246                 return prefix_path(prefix, prefixlen, copyfrom);
 247 }
 248
 249 const char **get_pathspec(const char *prefix, const char **pathspec)
 250 {
 251         const char *entry = *pathspec;
 252         const char **src, **dst;
 253         int prefixlen;
 254
 255         if (!prefix && !entry)
 256                 return NULL;
 257
 258         if (!entry) {
 259                 static const char *spec[2];
 260                 spec[0] = prefix;
 261                 spec[1] = NULL;
 262                 return spec;
 263         }
 264
 265         /* Otherwise we have to re-write the entries.. */
 266         src = pathspec;
 267         dst = pathspec;
 268         prefixlen = prefix ? strlen(prefix) : 0;
 269         while (*src) {
 270                 *(dst++) = prefix_pathspec(prefix, prefixlen, *src);
 271                 src++;
 272         }
 273         *dst = NULL;
 274         if (!*pathspec)
 275                 return NULL;
 276         return pathspec;
 277 }
 278
 279 /*
 280  * Test if it looks like we're at a git directory.
 281  * We want to see:
 282  *
 283  *  - either an objects/ directory _or_ the proper
 284  *    GIT_OBJECT_DIRECTORY environment variable
 285  *  - a refs/ directory
 286  *  - either a HEAD symlink or a HEAD file that is formatted as
 287  *    a proper "ref:", or a regular file HEAD that has a properly
 288  *    formatted sha1 object name.
 289  */
 290 int is_git_directory(const char *suspect)
 291 {
 292         char path[PATH_MAX];
 293         size_t len = strlen(suspect);
 294
 295         if (PATH_MAX <= len + strlen("/objects"))
 296                 die("Too long path: %.*s", 60, suspect);
 297         strcpy(path, suspect);
 298         if (getenv(DB_ENVIRONMENT)) {
 299                 if (access(getenv(DB_ENVIRONMENT), X_OK))
 300                         return 0;
 301         }
 302         else {
 303                 strcpy(path + len, "/objects");
 304                 if (access(path, X_OK))
 305                         return 0;
 306         }
 307
 308         strcpy(path + len, "/refs");
 309         if (access(path, X_OK))
 310                 return 0;
 311
 312         strcpy(path + len, "/HEAD");
 313         if (validate_headref(path))
 314                 return 0;
 315
 316         return 1;
 317 }
 318
 319 int is_inside_git_dir(void)
 320 {
 321         if (inside_git_dir < 0)
 322                 inside_git_dir = is_inside_dir(get_git_dir());
 323         return inside_git_dir;
 324 }
 325
 326 int is_inside_work_tree(void)
 327 {
 328         if (inside_work_tree < 0)
 329                 inside_work_tree = is_inside_dir(get_git_work_tree());
 330         return inside_work_tree;
 331 }
 332
 333 void setup_work_tree(void)
 334 {
 335         const char *work_tree, *git_dir;
 336         static int initialized = 0;
 337
 338         if (initialized)
 339                 return;
 340         work_tree = get_git_work_tree();
 341         git_dir = get_git_dir();
 342         if (!is_absolute_path(git_dir))
 343                 git_dir = real_path(get_git_dir());
 344         if (!work_tree || chdir(work_tree))
 345                 die("This operation must be run in a work tree");
 346
 347         /*
 348          * Make sure subsequent git processes find correct worktree
 349          * if $GIT_WORK_TREE is set relative
 350          */
 351         if (getenv(GIT_WORK_TREE_ENVIRONMENT))
 352                 setenv(GIT_WORK_TREE_ENVIRONMENT, ".", 1);
 353
 354         set_git_dir(relative_path(git_dir, work_tree));
 355         initialized = 1;
 356 }
 357
 358 static int check_repository_format_gently(const char *gitdir, int *nongit_ok)
 359 {
 360         char repo_config[PATH_MAX+1];
 361
 362         /*
 363          * git_config() can't be used here because it calls git_pathdup()
 364          * to get $GIT_CONFIG/config. That call will make setup_git_env()
 365          * set git_dir to ".git".
 366          *
 367          * We are in gitdir setup, no git dir has been found useable yet.
 368          * Use a gentler version of git_config() to check if this repo
 369          * is a good one.
 370          */
 371         snprintf(repo_config, PATH_MAX, "%s/config", gitdir);
 372         git_config_early(check_repository_format_version, NULL, repo_config);
 373         if (GIT_REPO_VERSION < repository_format_version) {
 374                 if (!nongit_ok)
 375                         die ("Expected git repo version <= %d, found %d",
 376                              GIT_REPO_VERSION, repository_format_version);
 377                 warning("Expected git repo version <= %d, found %d",
 378                         GIT_REPO_VERSION, repository_format_version);
 379                 warning("Please upgrade Git");
 380                 *nongit_ok = -1;
 381                 return -1;
 382         }
 383         return 0;
 384 }
 385
 386 /*
 387  * Try to read the location of the git directory from the .git file,
 388  * return path to git directory if found.
 389  */
 390 const char *read_gitfile(const char *path)
 391 {
 392         char *buf;
 393         char *dir;
 394         const char *slash;
 395         struct stat st;
 396         int fd;
 397         ssize_t len;
 398
 399         if (stat(path, &st))
 400                 return NULL;
 401         if (!S_ISREG(st.st_mode))
 402                 return NULL;
 403         fd = open(path, O_RDONLY);
 404         if (fd < 0)
 405                 die_errno("Error opening '%s'", path);
 406         buf = xmalloc(st.st_size + 1);
 407         len = read_in_full(fd, buf, st.st_size);
 408         close(fd);
 409         if (len != st.st_size)
 410                 die("Error reading %s", path);
 411         buf[len] = '\0';
 412         if (prefixcmp(buf, "gitdir: "))
 413                 die("Invalid gitfile format: %s", path);
 414         while (buf[len - 1] == '\n' || buf[len - 1] == '\r')
 415                 len--;
 416         if (len < 9)
 417                 die("No path in gitfile: %s", path);
 418         buf[len] = '\0';
 419         dir = buf + 8;
 420
 421         if (!is_absolute_path(dir) && (slash = strrchr(path, '/'))) {
 422                 size_t pathlen = slash+1 - path;
 423                 size_t dirlen = pathlen + len - 8;
 424                 dir = xmalloc(dirlen + 1);
 425                 strncpy(dir, path, pathlen);
 426                 strncpy(dir + pathlen, buf + 8, len - 8);
 427                 dir[dirlen] = '\0';
 428                 free(buf);
 429                 buf = dir;
 430         }
 431
 432         if (!is_git_directory(dir))
 433                 die("Not a git repository: %s", dir);
 434         path = real_path(dir);
 435
 436         free(buf);
 437         return path;
 438 }
 439
 440 static const char *setup_explicit_git_dir(const char *gitdirenv,
 441                                           char *cwd, int len,
 442                                           int *nongit_ok)
 443 {
 444         const char *work_tree_env = getenv(GIT_WORK_TREE_ENVIRONMENT);
 445         const char *worktree;
 446         char *gitfile;
 447         int offset;
 448
 449         if (PATH_MAX - 40 < strlen(gitdirenv))
 450                 die("'$%s' too big", GIT_DIR_ENVIRONMENT);
 451
 452         gitfile = (char*)read_gitfile(gitdirenv);
 453         if (gitfile) {
 454                 gitfile = xstrdup(gitfile);
 455                 gitdirenv = gitfile;
 456         }
 457
 458         if (!is_git_directory(gitdirenv)) {
 459                 if (nongit_ok) {
 460                         *nongit_ok = 1;
 461                         free(gitfile);
 462                         return NULL;
 463                 }
 464                 die("Not a git repository: '%s'", gitdirenv);
 465         }
 466
 467         if (check_repository_format_gently(gitdirenv, nongit_ok)) {
 468                 free(gitfile);
 469                 return NULL;
 470         }
 471
 472         /* #3, #7, #11, #15, #19, #23, #27, #31 (see t1510) */
 473         if (work_tree_env)
 474                 set_git_work_tree(work_tree_env);
 475         else if (is_bare_repository_cfg > 0) {
 476                 if (git_work_tree_cfg) /* #22.2, #30 */
 477                         die("core.bare and core.worktree do not make sense");
 478
 479                 /* #18, #26 */
 480                 set_git_dir(gitdirenv);
 481                 free(gitfile);
 482                 return NULL;
 483         }
 484         else if (git_work_tree_cfg) { /* #6, #14 */
 485                 if (is_absolute_path(git_work_tree_cfg))
 486                         set_git_work_tree(git_work_tree_cfg);
 487                 else {
 488                         char core_worktree[PATH_MAX];
 489                         if (chdir(gitdirenv))
 490                                 die_errno("Could not chdir to '%s'", gitdirenv);
 491                         if (chdir(git_work_tree_cfg))
 492                                 die_errno("Could not chdir to '%s'", git_work_tree_cfg);
 493                         if (!getcwd(core_worktree, PATH_MAX))
 494                                 die_errno("Could not get directory '%s'", git_work_tree_cfg);
 495                         if (chdir(cwd))
 496                                 die_errno("Could not come back to cwd");
 497                         set_git_work_tree(core_worktree);
 498                 }
 499         }
 500         else /* #2, #10 */
 501                 set_git_work_tree(".");
 502
 503         /* set_git_work_tree() must have been called by now */
 504         worktree = get_git_work_tree();
 505
 506         /* both get_git_work_tree() and cwd are already normalized */
 507         if (!strcmp(cwd, worktree)) { /* cwd == worktree */
 508                 set_git_dir(gitdirenv);
 509                 free(gitfile);
 510                 return NULL;
 511         }
 512
 513         offset = dir_inside_of(cwd, worktree);
 514         if (offset >= 0) {      /* cwd inside worktree? */
 515                 set_git_dir(real_path(gitdirenv));
 516                 if (chdir(worktree))
 517                         die_errno("Could not chdir to '%s'", worktree);
 518                 cwd[len++] = '/';
 519                 cwd[len] = '\0';
 520                 free(gitfile);
 521                 return cwd + offset;
 522         }
 523
 524         /* cwd outside worktree */
 525         set_git_dir(gitdirenv);
 526         free(gitfile);
 527         return NULL;
 528 }
 529
 530 static const char *setup_discovered_git_dir(const char *gitdir,
 531                                             char *cwd, int offset, int len,
 532                                             int *nongit_ok)
 533 {
 534         if (check_repository_format_gently(gitdir, nongit_ok))
 535                 return NULL;
 536
 537         /* --work-tree is set without --git-dir; use discovered one */
 538         if (getenv(GIT_WORK_TREE_ENVIRONMENT) || git_work_tree_cfg) {
 539                 if (offset != len && !is_absolute_path(gitdir))
 540                         gitdir = xstrdup(real_path(gitdir));
 541                 if (chdir(cwd))
 542                         die_errno("Could not come back to cwd");
 543                 return setup_explicit_git_dir(gitdir, cwd, len, nongit_ok);
 544         }
 545
 546         /* #16.2, #17.2, #20.2, #21.2, #24, #25, #28, #29 (see t1510) */
 547         if (is_bare_repository_cfg > 0) {
 548                 set_git_dir(offset == len ? gitdir : real_path(gitdir));
 549                 if (chdir(cwd))
 550                         die_errno("Could not come back to cwd");
 551                 return NULL;
 552         }
 553
 554         /* #0, #1, #5, #8, #9, #12, #13 */
 555         set_git_work_tree(".");
 556         if (strcmp(gitdir, DEFAULT_GIT_DIR_ENVIRONMENT))
 557                 set_git_dir(gitdir);
 558         inside_git_dir = 0;
 559         inside_work_tree = 1;
 560         if (offset == len)
 561                 return NULL;
 562
 563         /* Make "offset" point to past the '/', and add a '/' at the end */
 564         offset++;
 565         cwd[len++] = '/';
 566         cwd[len] = 0;
 567         return cwd + offset;
 568 }
 569
 570 /* #16.1, #17.1, #20.1, #21.1, #22.1 (see t1510) */
 571 static const char *setup_bare_git_dir(char *cwd, int offset, int len, int *nongit_ok)
 572 {
 573         int root_len;
 574
 575         if (check_repository_format_gently(".", nongit_ok))
 576                 return NULL;
 577
 578         /* --work-tree is set without --git-dir; use discovered one */
 579         if (getenv(GIT_WORK_TREE_ENVIRONMENT) || git_work_tree_cfg) {
 580                 const char *gitdir;
 581
 582                 gitdir = offset == len ? "." : xmemdupz(cwd, offset);
 583                 if (chdir(cwd))
 584                         die_errno("Could not come back to cwd");
 585                 return setup_explicit_git_dir(gitdir, cwd, len, nongit_ok);
 586         }
 587
 588         inside_git_dir = 1;
 589         inside_work_tree = 0;
 590         if (offset != len) {
 591                 if (chdir(cwd))
 592                         die_errno("Cannot come back to cwd");
 593                 root_len = offset_1st_component(cwd);
 594                 cwd[offset > root_len ? offset : root_len] = '\0';
 595                 set_git_dir(cwd);
 596         }
 597         else
 598                 set_git_dir(".");
 599         return NULL;
 600 }
 601
 602 static const char *setup_nongit(const char *cwd, int *nongit_ok)
 603 {
 604         if (!nongit_ok)
 605                 die("Not a git repository (or any of the parent directories): %s", DEFAULT_GIT_DIR_ENVIRONMENT);
 606         if (chdir(cwd))
 607                 die_errno("Cannot come back to cwd");
 608         *nongit_ok = 1;
 609         return NULL;
 610 }
 611
 612 static dev_t get_device_or_die(const char *path, const char *prefix, int prefix_len)
 613 {
 614         struct stat buf;
 615         if (stat(path, &buf)) {
 616                 die_errno("failed to stat '%*s%s%s'",
 617                                 prefix_len,
 618                                 prefix ? prefix : "",
 619                                 prefix ? "/" : "", path);
 620         }
 621         return buf.st_dev;
 622 }
 623
 624 /*
 625  * A "string_list_each_func_t" function that canonicalizes an entry
 626  * from GIT_CEILING_DIRECTORIES using real_path_if_valid(), or
 627  * discards it if unusable.
 628  */
 629 static int canonicalize_ceiling_entry(struct string_list_item *item,
 630                                       void *unused)
 631 {
 632         char *ceil = item->string;
 633         const char *real_path;
 634
 635         if (!*ceil || !is_absolute_path(ceil))
 636                 return 0;
 637         real_path = real_path_if_valid(ceil);
 638         if (!real_path)
 639                 return 0;
 640         free(item->string);
 641         item->string = xstrdup(real_path);
 642         return 1;
 643 }
 644
 645 /*
 646  * We cannot decide in this function whether we are in the work tree or
 647  * not, since the config can only be read _after_ this function was called.
 648  */
 649 static const char *setup_git_directory_gently_1(int *nongit_ok)
 650 {
 651         const char *env_ceiling_dirs = getenv(CEILING_DIRECTORIES_ENVIRONMENT);
 652         struct string_list ceiling_dirs = STRING_LIST_INIT_DUP;
 653         static char cwd[PATH_MAX+1];
 654         const char *gitdirenv, *ret;
 655         char *gitfile;
 656         int len, offset, offset_parent, ceil_offset = -1;
 657         dev_t current_device = 0;
 658         int one_filesystem = 1;
 659
 660         /*
 661          * Let's assume that we are in a git repository.
 662          * If it turns out later that we are somewhere else, the value will be
 663          * updated accordingly.
 664          */
 665         if (nongit_ok)
 666                 *nongit_ok = 0;
 667
 668         if (!getcwd(cwd, sizeof(cwd)-1))
 669                 die_errno("Unable to read current working directory");
 670         offset = len = strlen(cwd);
 671
 672         /*
 673          * If GIT_DIR is set explicitly, we're not going
 674          * to do any discovery, but we still do repository
 675          * validation.
 676          */
 677         gitdirenv = getenv(GIT_DIR_ENVIRONMENT);
 678         if (gitdirenv)
 679                 return setup_explicit_git_dir(gitdirenv, cwd, len, nongit_ok);
 680
 681         if (env_ceiling_dirs) {
 682                 string_list_split(&ceiling_dirs, env_ceiling_dirs, PATH_SEP, -1);
 683                 filter_string_list(&ceiling_dirs, 0,
 684                                    canonicalize_ceiling_entry, NULL);
 685                 ceil_offset = longest_ancestor_length(cwd, &ceiling_dirs);
 686                 string_list_clear(&ceiling_dirs, 0);
 687         }
 688
 689         if (ceil_offset < 0 && has_dos_drive_prefix(cwd))
 690                 ceil_offset = 1;
 691
 692         /*
 693          * Test in the following order (relative to the cwd):
 694          * - .git (file containing "gitdir: <path>")
 695          * - .git/
 696          * - ./ (bare)
 697          * - ../.git
 698          * - ../.git/
 699          * - ../ (bare)
 700          * - ../../.git/
 701          *   etc.
 702          */
 703         one_filesystem = !git_env_bool("GIT_DISCOVERY_ACROSS_FILESYSTEM", 0);
 704         if (one_filesystem)
 705                 current_device = get_device_or_die(".", NULL, 0);
 706         for (;;) {
 707                 gitfile = (char*)read_gitfile(DEFAULT_GIT_DIR_ENVIRONMENT);
 708                 if (gitfile)
 709                         gitdirenv = gitfile = xstrdup(gitfile);
 710                 else {
 711                         if (is_git_directory(DEFAULT_GIT_DIR_ENVIRONMENT))
 712                                 gitdirenv = DEFAULT_GIT_DIR_ENVIRONMENT;
 713                 }
 714
 715                 if (gitdirenv) {
 716                         ret = setup_discovered_git_dir(gitdirenv,
 717                                                        cwd, offset, len,
 718                                                        nongit_ok);
 719                         free(gitfile);
 720                         return ret;
 721                 }
 722                 free(gitfile);
 723
 724                 if (is_git_directory("."))
 725                         return setup_bare_git_dir(cwd, offset, len, nongit_ok);
 726
 727                 offset_parent = offset;
 728                 while (--offset_parent > ceil_offset && cwd[offset_parent] != '/');
 729                 if (offset_parent <= ceil_offset)
 730                         return setup_nongit(cwd, nongit_ok);
 731                 if (one_filesystem) {
 732                         dev_t parent_device = get_device_or_die("..", cwd, offset);
 733                         if (parent_device != current_device) {
 734                                 if (nongit_ok) {
 735                                         if (chdir(cwd))
 736                                                 die_errno("Cannot come back to cwd");
 737                                         *nongit_ok = 1;
 738                                         return NULL;
 739                                 }
 740                                 cwd[offset] = '\0';
 741                                 die("Not a git repository (or any parent up to mount point %s)\n"
 742                                 "Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set).", cwd);
 743                         }
 744                 }
 745                 if (chdir("..")) {
 746                         cwd[offset] = '\0';
 747                         die_errno("Cannot change to '%s/..'", cwd);
 748                 }
 749                 offset = offset_parent;
 750         }
 751 }
 752
 753 const char *setup_git_directory_gently(int *nongit_ok)
 754 {
 755         const char *prefix;
 756
 757         prefix = setup_git_directory_gently_1(nongit_ok);
 758         if (prefix)
 759                 setenv("GIT_PREFIX", prefix, 1);
 760         else
 761                 setenv("GIT_PREFIX", "", 1);
 762
 763         if (startup_info) {
 764                 startup_info->have_repository = !nongit_ok || !*nongit_ok;
 765                 startup_info->prefix = prefix;
 766         }
 767         return prefix;
 768 }
 769
 770 int git_config_perm(const char *var, const char *value)
 771 {
 772         int i;
 773         char *endptr;
 774
 775         if (value == NULL)
 776                 return PERM_GROUP;
 777
 778         if (!strcmp(value, "umask"))
 779                 return PERM_UMASK;
 780         if (!strcmp(value, "group"))
 781                 return PERM_GROUP;
 782         if (!strcmp(value, "all") ||
 783             !strcmp(value, "world") ||
 784             !strcmp(value, "everybody"))
 785                 return PERM_EVERYBODY;
 786
 787         /* Parse octal numbers */
 788         i = strtol(value, &endptr, 8);
 789
 790         /* If not an octal number, maybe true/false? */
 791         if (*endptr != 0)
 792                 return git_config_bool(var, value) ? PERM_GROUP : PERM_UMASK;
 793
 794         /*
 795          * Treat values 0, 1 and 2 as compatibility cases, otherwise it is
 796          * a chmod value to restrict to.
 797          */
 798         switch (i) {
 799         case PERM_UMASK:               /* 0 */
 800                 return PERM_UMASK;
 801         case OLD_PERM_GROUP:           /* 1 */
 802                 return PERM_GROUP;
 803         case OLD_PERM_EVERYBODY:       /* 2 */
 804                 return PERM_EVERYBODY;
 805         }
 806
 807         /* A filemode value was given: 0xxx */
 808
 809         if ((i & 0600) != 0600)
 810                 die("Problem with core.sharedRepository filemode value "
 811                     "(0%.3o).\nThe owner of files must always have "
 812                     "read and write permissions.", i);
 813
 814         /*
 815          * Mask filemode value. Others can not get write permission.
 816          * x flags for directories are handled separately.
 817          */
 818         return -(i & 0666);
 819 }
 820
 821 int check_repository_format_version(const char *var, const char *value, void *cb)
 822 {
 823         if (strcmp(var, "core.repositoryformatversion") == 0)
 824                 repository_format_version = git_config_int(var, value);
 825         else if (strcmp(var, "core.sharedrepository") == 0)
 826                 shared_repository = git_config_perm(var, value);
 827         else if (strcmp(var, "core.bare") == 0) {
 828                 is_bare_repository_cfg = git_config_bool(var, value);
 829                 if (is_bare_repository_cfg == 1)
 830                         inside_work_tree = -1;
 831         } else if (strcmp(var, "core.worktree") == 0) {
 832                 if (!value)
 833                         return config_error_nonbool(var);
 834                 free(git_work_tree_cfg);
 835                 git_work_tree_cfg = xstrdup(value);
 836                 inside_work_tree = -1;
 837         }
 838         return 0;
 839 }
 840
 841 int check_repository_format(void)
 842 {
 843         return check_repository_format_gently(get_git_dir(), NULL);
 844 }
 845
 846 /*
 847  * Returns the "prefix", a path to the current working directory
 848  * relative to the work tree root, or NULL, if the current working
 849  * directory is not a strict subdirectory of the work tree root. The
 850  * prefix always ends with a '/' character.
 851  */
 852 const char *setup_git_directory(void)
 853 {
 854         return setup_git_directory_gently(NULL);
 855 }
 856
 857 const char *resolve_gitdir(const char *suspect)
 858 {
 859         if (is_git_directory(suspect))
 860                 return suspect;
 861         return read_gitfile(suspect);
 862 }