path.c

   1 /*
   2  * Utilities for paths and pathnames
   3  */
   4 #include "cache.h"
   5 #include "strbuf.h"
   6 #include "string-list.h"
   7
   8 #ifndef get_st_mode_bits
   9 /*
  10  * The replacement lstat(2) we use on Cygwin is incomplete and
  11  * may return wrong permission bits. Most of the time we do not care,
  12  * but the callsites of this wrapper do care.
  13  */
  14 int get_st_mode_bits(const char *path, int *mode)
  15 {
  16         struct stat st;
  17         if (lstat(path, &st) < 0)
  18                 return -1;
  19         *mode = st.st_mode;
  20         return 0;
  21 }
  22 #endif
  23
  24 static char bad_path[] = "/bad-path/";
  25
  26 static char *get_pathname(void)
  27 {
  28         static char pathname_array[4][PATH_MAX];
  29         static int index;
  30         return pathname_array[3 & ++index];
  31 }
  32
  33 static char *cleanup_path(char *path)
  34 {
  35         /* Clean it up */
  36         if (!memcmp(path, "./", 2)) {
  37                 path += 2;
  38                 while (*path == '/')
  39                         path++;
  40         }
  41         return path;
  42 }
  43
  44 char *mksnpath(char *buf, size_t n, const char *fmt, ...)
  45 {
  46         va_list args;
  47         unsigned len;
  48
  49         va_start(args, fmt);
  50         len = vsnprintf(buf, n, fmt, args);
  51         va_end(args);
  52         if (len >= n) {
  53                 strlcpy(buf, bad_path, n);
  54                 return buf;
  55         }
  56         return cleanup_path(buf);
  57 }
  58
  59 static char *vsnpath(char *buf, size_t n, const char *fmt, va_list args)
  60 {
  61         const char *git_dir = get_git_dir();
  62         size_t len;
  63
  64         len = strlen(git_dir);
  65         if (n < len + 1)
  66                 goto bad;
  67         memcpy(buf, git_dir, len);
  68         if (len && !is_dir_sep(git_dir[len-1]))
  69                 buf[len++] = '/';
  70         len += vsnprintf(buf + len, n - len, fmt, args);
  71         if (len >= n)
  72                 goto bad;
  73         return cleanup_path(buf);
  74 bad:
  75         strlcpy(buf, bad_path, n);
  76         return buf;
  77 }
  78
  79 char *git_snpath(char *buf, size_t n, const char *fmt, ...)
  80 {
  81         char *ret;
  82         va_list args;
  83         va_start(args, fmt);
  84         ret = vsnpath(buf, n, fmt, args);
  85         va_end(args);
  86         return ret;
  87 }
  88
  89 char *git_pathdup(const char *fmt, ...)
  90 {
  91         char path[PATH_MAX], *ret;
  92         va_list args;
  93         va_start(args, fmt);
  94         ret = vsnpath(path, sizeof(path), fmt, args);
  95         va_end(args);
  96         return xstrdup(ret);
  97 }
  98
  99 char *mkpathdup(const char *fmt, ...)
 100 {
 101         char *path;
 102         struct strbuf sb = STRBUF_INIT;
 103         va_list args;
 104
 105         va_start(args, fmt);
 106         strbuf_vaddf(&sb, fmt, args);
 107         va_end(args);
 108         path = xstrdup(cleanup_path(sb.buf));
 109
 110         strbuf_release(&sb);
 111         return path;
 112 }
 113
 114 char *mkpath(const char *fmt, ...)
 115 {
 116         va_list args;
 117         unsigned len;
 118         char *pathname = get_pathname();
 119
 120         va_start(args, fmt);
 121         len = vsnprintf(pathname, PATH_MAX, fmt, args);
 122         va_end(args);
 123         if (len >= PATH_MAX)
 124                 return bad_path;
 125         return cleanup_path(pathname);
 126 }
 127
 128 char *git_path(const char *fmt, ...)
 129 {
 130         char *pathname = get_pathname();
 131         va_list args;
 132         char *ret;
 133
 134         va_start(args, fmt);
 135         ret = vsnpath(pathname, PATH_MAX, fmt, args);
 136         va_end(args);
 137         return ret;
 138 }
 139
 140 void home_config_paths(char **global, char **xdg, char *file)
 141 {
 142         char *xdg_home = getenv("XDG_CONFIG_HOME");
 143         char *home = getenv("HOME");
 144         char *to_free = NULL;
 145
 146         if (!home) {
 147                 if (global)
 148                         *global = NULL;
 149         } else {
 150                 if (!xdg_home) {
 151                         to_free = mkpathdup("%s/.config", home);
 152                         xdg_home = to_free;
 153                 }
 154                 if (global)
 155                         *global = mkpathdup("%s/.gitconfig", home);
 156         }
 157
 158         if (!xdg_home)
 159                 *xdg = NULL;
 160         else
 161                 *xdg = mkpathdup("%s/git/%s", xdg_home, file);
 162
 163         free(to_free);
 164 }
 165
 166 char *git_path_submodule(const char *path, const char *fmt, ...)
 167 {
 168         char *pathname = get_pathname();
 169         struct strbuf buf = STRBUF_INIT;
 170         const char *git_dir;
 171         va_list args;
 172         unsigned len;
 173
 174         len = strlen(path);
 175         if (len > PATH_MAX-100)
 176                 return bad_path;
 177
 178         strbuf_addstr(&buf, path);
 179         if (len && path[len-1] != '/')
 180                 strbuf_addch(&buf, '/');
 181         strbuf_addstr(&buf, ".git");
 182
 183         git_dir = read_gitfile(buf.buf);
 184         if (git_dir) {
 185                 strbuf_reset(&buf);
 186                 strbuf_addstr(&buf, git_dir);
 187         }
 188         strbuf_addch(&buf, '/');
 189
 190         if (buf.len >= PATH_MAX)
 191                 return bad_path;
 192         memcpy(pathname, buf.buf, buf.len + 1);
 193
 194         strbuf_release(&buf);
 195         len = strlen(pathname);
 196
 197         va_start(args, fmt);
 198         len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
 199         va_end(args);
 200         if (len >= PATH_MAX)
 201                 return bad_path;
 202         return cleanup_path(pathname);
 203 }
 204
 205 int validate_headref(const char *path)
 206 {
 207         struct stat st;
 208         char *buf, buffer[256];
 209         unsigned char sha1[20];
 210         int fd;
 211         ssize_t len;
 212
 213         if (lstat(path, &st) < 0)
 214                 return -1;
 215
 216         /* Make sure it is a "refs/.." symlink */
 217         if (S_ISLNK(st.st_mode)) {
 218                 len = readlink(path, buffer, sizeof(buffer)-1);
 219                 if (len >= 5 && !memcmp("refs/", buffer, 5))
 220                         return 0;
 221                 return -1;
 222         }
 223
 224         /*
 225          * Anything else, just open it and try to see if it is a symbolic ref.
 226          */
 227         fd = open(path, O_RDONLY);
 228         if (fd < 0)
 229                 return -1;
 230         len = read_in_full(fd, buffer, sizeof(buffer)-1);
 231         close(fd);
 232
 233         /*
 234          * Is it a symbolic ref?
 235          */
 236         if (len < 4)
 237                 return -1;
 238         if (!memcmp("ref:", buffer, 4)) {
 239                 buf = buffer + 4;
 240                 len -= 4;
 241                 while (len && isspace(*buf))
 242                         buf++, len--;
 243                 if (len >= 5 && !memcmp("refs/", buf, 5))
 244                         return 0;
 245         }
 246
 247         /*
 248          * Is this a detached HEAD?
 249          */
 250         if (!get_sha1_hex(buffer, sha1))
 251                 return 0;
 252
 253         return -1;
 254 }
 255
 256 static struct passwd *getpw_str(const char *username, size_t len)
 257 {
 258         struct passwd *pw;
 259         char *username_z = xmalloc(len + 1);
 260         memcpy(username_z, username, len);
 261         username_z[len] = '\0';
 262         pw = getpwnam(username_z);
 263         free(username_z);
 264         return pw;
 265 }
 266
 267 /*
 268  * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 269  * then it is a newly allocated string. Returns NULL on getpw failure or
 270  * if path is NULL.
 271  */
 272 char *expand_user_path(const char *path)
 273 {
 274         struct strbuf user_path = STRBUF_INIT;
 275         const char *first_slash = strchrnul(path, '/');
 276         const char *to_copy = path;
 277
 278         if (path == NULL)
 279                 goto return_null;
 280         if (path[0] == '~') {
 281                 const char *username = path + 1;
 282                 size_t username_len = first_slash - username;
 283                 if (username_len == 0) {
 284                         const char *home = getenv("HOME");
 285                         if (!home)
 286                                 goto return_null;
 287                         strbuf_add(&user_path, home, strlen(home));
 288                 } else {
 289                         struct passwd *pw = getpw_str(username, username_len);
 290                         if (!pw)
 291                                 goto return_null;
 292                         strbuf_add(&user_path, pw->pw_dir, strlen(pw->pw_dir));
 293                 }
 294                 to_copy = first_slash;
 295         }
 296         strbuf_add(&user_path, to_copy, strlen(to_copy));
 297         return strbuf_detach(&user_path, NULL);
 298 return_null:
 299         strbuf_release(&user_path);
 300         return NULL;
 301 }
 302
 303 /*
 304  * First, one directory to try is determined by the following algorithm.
 305  *
 306  * (0) If "strict" is given, the path is used as given and no DWIM is
 307  *     done. Otherwise:
 308  * (1) "~/path" to mean path under the running user's home directory;
 309  * (2) "~user/path" to mean path under named user's home directory;
 310  * (3) "relative/path" to mean cwd relative directory; or
 311  * (4) "/absolute/path" to mean absolute directory.
 312  *
 313  * Unless "strict" is given, we try access() for existence of "%s.git/.git",
 314  * "%s/.git", "%s.git", "%s" in this order.  The first one that exists is
 315  * what we try.
 316  *
 317  * Second, we try chdir() to that.  Upon failure, we return NULL.
 318  *
 319  * Then, we try if the current directory is a valid git repository.
 320  * Upon failure, we return NULL.
 321  *
 322  * If all goes well, we return the directory we used to chdir() (but
 323  * before ~user is expanded), avoiding getcwd() resolving symbolic
 324  * links.  User relative paths are also returned as they are given,
 325  * except DWIM suffixing.
 326  */
 327 const char *enter_repo(const char *path, int strict)
 328 {
 329         static char used_path[PATH_MAX];
 330         static char validated_path[PATH_MAX];
 331
 332         if (!path)
 333                 return NULL;
 334
 335         if (!strict) {
 336                 static const char *suffix[] = {
 337                         "/.git", "", ".git/.git", ".git", NULL,
 338                 };
 339                 const char *gitfile;
 340                 int len = strlen(path);
 341                 int i;
 342                 while ((1 < len) && (path[len-1] == '/'))
 343                         len--;
 344
 345                 if (PATH_MAX <= len)
 346                         return NULL;
 347                 strncpy(used_path, path, len); used_path[len] = 0 ;
 348                 strcpy(validated_path, used_path);
 349
 350                 if (used_path[0] == '~') {
 351                         char *newpath = expand_user_path(used_path);
 352                         if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
 353                                 free(newpath);
 354                                 return NULL;
 355                         }
 356                         /*
 357                          * Copy back into the static buffer. A pity
 358                          * since newpath was not bounded, but other
 359                          * branches of the if are limited by PATH_MAX
 360                          * anyway.
 361                          */
 362                         strcpy(used_path, newpath); free(newpath);
 363                 }
 364                 else if (PATH_MAX - 10 < len)
 365                         return NULL;
 366                 len = strlen(used_path);
 367                 for (i = 0; suffix[i]; i++) {
 368                         struct stat st;
 369                         strcpy(used_path + len, suffix[i]);
 370                         if (!stat(used_path, &st) &&
 371                             (S_ISREG(st.st_mode) ||
 372                             (S_ISDIR(st.st_mode) && is_git_directory(used_path)))) {
 373                                 strcat(validated_path, suffix[i]);
 374                                 break;
 375                         }
 376                 }
 377                 if (!suffix[i])
 378                         return NULL;
 379                 gitfile = read_gitfile(used_path) ;
 380                 if (gitfile)
 381                         strcpy(used_path, gitfile);
 382                 if (chdir(used_path))
 383                         return NULL;
 384                 path = validated_path;
 385         }
 386         else if (chdir(path))
 387                 return NULL;
 388
 389         if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
 390             validate_headref("HEAD") == 0) {
 391                 set_git_dir(".");
 392                 check_repository_format();
 393                 return path;
 394         }
 395
 396         return NULL;
 397 }
 398
 399 static int calc_shared_perm(int mode)
 400 {
 401         int tweak;
 402
 403         if (shared_repository < 0)
 404                 tweak = -shared_repository;
 405         else
 406                 tweak = shared_repository;
 407
 408         if (!(mode & S_IWUSR))
 409                 tweak &= ~0222;
 410         if (mode & S_IXUSR)
 411                 /* Copy read bits to execute bits */
 412                 tweak |= (tweak & 0444) >> 2;
 413         if (shared_repository < 0)
 414                 mode = (mode & ~0777) | tweak;
 415         else
 416                 mode |= tweak;
 417
 418         return mode;
 419 }
 420
 421
 422 int adjust_shared_perm(const char *path)
 423 {
 424         int old_mode, new_mode;
 425
 426         if (!shared_repository)
 427                 return 0;
 428         if (get_st_mode_bits(path, &old_mode) < 0)
 429                 return -1;
 430
 431         new_mode = calc_shared_perm(old_mode);
 432         if (S_ISDIR(old_mode)) {
 433                 /* Copy read bits to execute bits */
 434                 new_mode |= (new_mode & 0444) >> 2;
 435                 new_mode |= FORCE_DIR_SET_GID;
 436         }
 437
 438         if (((old_mode ^ new_mode) & ~S_IFMT) &&
 439                         chmod(path, (new_mode & ~S_IFMT)) < 0)
 440                 return -2;
 441         return 0;
 442 }
 443
 444 /*
 445  * Give path as relative to prefix.
 446  *
 447  * The strbuf may or may not be used, so do not assume it contains the
 448  * returned path.
 449  */
 450 const char *relative_path(const char *in, const char *prefix,
 451                           struct strbuf *sb)
 452 {
 453         int in_len = in ? strlen(in) : 0;
 454         int prefix_len = prefix ? strlen(prefix) : 0;
 455         int in_off = 0;
 456         int prefix_off = 0;
 457         int i = 0, j = 0;
 458
 459         if (!in_len)
 460                 return "./";
 461         else if (!prefix_len)
 462                 return in;
 463
 464         while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 465                 if (is_dir_sep(prefix[i])) {
 466                         while (is_dir_sep(prefix[i]))
 467                                 i++;
 468                         while (is_dir_sep(in[j]))
 469                                 j++;
 470                         prefix_off = i;
 471                         in_off = j;
 472                 } else {
 473                         i++;
 474                         j++;
 475                 }
 476         }
 477
 478         if (
 479             /* "prefix" seems like prefix of "in" */
 480             i >= prefix_len &&
 481             /*
 482              * but "/foo" is not a prefix of "/foobar"
 483              * (i.e. prefix not end with '/')
 484              */
 485             prefix_off < prefix_len) {
 486                 if (j >= in_len) {
 487                         /* in="/a/b", prefix="/a/b" */
 488                         in_off = in_len;
 489                 } else if (is_dir_sep(in[j])) {
 490                         /* in="/a/b/c", prefix="/a/b" */
 491                         while (is_dir_sep(in[j]))
 492                                 j++;
 493                         in_off = j;
 494                 } else {
 495                         /* in="/a/bbb/c", prefix="/a/b" */
 496                         i = prefix_off;
 497                 }
 498         } else if (
 499                    /* "in" is short than "prefix" */
 500                    j >= in_len &&
 501                    /* "in" not end with '/' */
 502                    in_off < in_len) {
 503                 if (is_dir_sep(prefix[i])) {
 504                         /* in="/a/b", prefix="/a/b/c/" */
 505                         while (is_dir_sep(prefix[i]))
 506                                 i++;
 507                         in_off = in_len;
 508                 }
 509         }
 510         in += in_off;
 511         in_len -= in_off;
 512
 513         if (i >= prefix_len) {
 514                 if (!in_len)
 515                         return "./";
 516                 else
 517                         return in;
 518         }
 519
 520         strbuf_reset(sb);
 521         strbuf_grow(sb, in_len);
 522
 523         while (i < prefix_len) {
 524                 if (is_dir_sep(prefix[i])) {
 525                         strbuf_addstr(sb, "../");
 526                         while (is_dir_sep(prefix[i]))
 527                                 i++;
 528                         continue;
 529                 }
 530                 i++;
 531         }
 532         if (!is_dir_sep(prefix[prefix_len - 1]))
 533                 strbuf_addstr(sb, "../");
 534
 535         strbuf_addstr(sb, in);
 536
 537         return sb->buf;
 538 }
 539
 540 /*
 541  * It is okay if dst == src, but they should not overlap otherwise.
 542  *
 543  * Performs the following normalizations on src, storing the result in dst:
 544  * - Ensures that components are separated by '/' (Windows only)
 545  * - Squashes sequences of '/'.
 546  * - Removes "." components.
 547  * - Removes ".." components, and the components the precede them.
 548  * Returns failure (non-zero) if a ".." component appears as first path
 549  * component anytime during the normalization. Otherwise, returns success (0).
 550  *
 551  * Note that this function is purely textual.  It does not follow symlinks,
 552  * verify the existence of the path, or make any system calls.
 553  */
 554 int normalize_path_copy(char *dst, const char *src)
 555 {
 556         char *dst0;
 557
 558         if (has_dos_drive_prefix(src)) {
 559                 *dst++ = *src++;
 560                 *dst++ = *src++;
 561         }
 562         dst0 = dst;
 563
 564         if (is_dir_sep(*src)) {
 565                 *dst++ = '/';
 566                 while (is_dir_sep(*src))
 567                         src++;
 568         }
 569
 570         for (;;) {
 571                 char c = *src;
 572
 573                 /*
 574                  * A path component that begins with . could be
 575                  * special:
 576                  * (1) "." and ends   -- ignore and terminate.
 577                  * (2) "./"           -- ignore them, eat slash and continue.
 578                  * (3) ".." and ends  -- strip one and terminate.
 579                  * (4) "../"          -- strip one, eat slash and continue.
 580                  */
 581                 if (c == '.') {
 582                         if (!src[1]) {
 583                                 /* (1) */
 584                                 src++;
 585                         } else if (is_dir_sep(src[1])) {
 586                                 /* (2) */
 587                                 src += 2;
 588                                 while (is_dir_sep(*src))
 589                                         src++;
 590                                 continue;
 591                         } else if (src[1] == '.') {
 592                                 if (!src[2]) {
 593                                         /* (3) */
 594                                         src += 2;
 595                                         goto up_one;
 596                                 } else if (is_dir_sep(src[2])) {
 597                                         /* (4) */
 598                                         src += 3;
 599                                         while (is_dir_sep(*src))
 600                                                 src++;
 601                                         goto up_one;
 602                                 }
 603                         }
 604                 }
 605
 606                 /* copy up to the next '/', and eat all '/' */
 607                 while ((c = *src++) != '\0' && !is_dir_sep(c))
 608                         *dst++ = c;
 609                 if (is_dir_sep(c)) {
 610                         *dst++ = '/';
 611                         while (is_dir_sep(c))
 612                                 c = *src++;
 613                         src--;
 614                 } else if (!c)
 615                         break;
 616                 continue;
 617
 618         up_one:
 619                 /*
 620                  * dst0..dst is prefix portion, and dst[-1] is '/';
 621                  * go up one level.
 622                  */
 623                 dst--;  /* go to trailing '/' */
 624                 if (dst <= dst0)
 625                         return -1;
 626                 /* Windows: dst[-1] cannot be backslash anymore */
 627                 while (dst0 < dst && dst[-1] != '/')
 628                         dst--;
 629         }
 630         *dst = '\0';
 631         return 0;
 632 }
 633
 634 /*
 635  * path = Canonical absolute path
 636  * prefixes = string_list containing normalized, absolute paths without
 637  * trailing slashes (except for the root directory, which is denoted by "/").
 638  *
 639  * Determines, for each path in prefixes, whether the "prefix"
 640  * is an ancestor directory of path.  Returns the length of the longest
 641  * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 642  * is an ancestor.  (Note that this means 0 is returned if prefixes is
 643  * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
 644  * are not considered to be their own ancestors.  path must be in a
 645  * canonical form: empty components, or "." or ".." components are not
 646  * allowed.
 647  */
 648 int longest_ancestor_length(const char *path, struct string_list *prefixes)
 649 {
 650         int i, max_len = -1;
 651
 652         if (!strcmp(path, "/"))
 653                 return -1;
 654
 655         for (i = 0; i < prefixes->nr; i++) {
 656                 const char *ceil = prefixes->items[i].string;
 657                 int len = strlen(ceil);
 658
 659                 if (len == 1 && ceil[0] == '/')
 660                         len = 0; /* root matches anything, with length 0 */
 661                 else if (!strncmp(path, ceil, len) && path[len] == '/')
 662                         ; /* match of length len */
 663                 else
 664                         continue; /* no match */
 665
 666                 if (len > max_len)
 667                         max_len = len;
 668         }
 669
 670         return max_len;
 671 }
 672
 673 /* strip arbitrary amount of directory separators at end of path */
 674 static inline int chomp_trailing_dir_sep(const char *path, int len)
 675 {
 676         while (len && is_dir_sep(path[len - 1]))
 677                 len--;
 678         return len;
 679 }
 680
 681 /*
 682  * If path ends with suffix (complete path components), returns the
 683  * part before suffix (sans trailing directory separators).
 684  * Otherwise returns NULL.
 685  */
 686 char *strip_path_suffix(const char *path, const char *suffix)
 687 {
 688         int path_len = strlen(path), suffix_len = strlen(suffix);
 689
 690         while (suffix_len) {
 691                 if (!path_len)
 692                         return NULL;
 693
 694                 if (is_dir_sep(path[path_len - 1])) {
 695                         if (!is_dir_sep(suffix[suffix_len - 1]))
 696                                 return NULL;
 697                         path_len = chomp_trailing_dir_sep(path, path_len);
 698                         suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 699                 }
 700                 else if (path[--path_len] != suffix[--suffix_len])
 701                         return NULL;
 702         }
 703
 704         if (path_len && !is_dir_sep(path[path_len - 1]))
 705                 return NULL;
 706         return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
 707 }
 708
 709 int daemon_avoid_alias(const char *p)
 710 {
 711         int sl, ndot;
 712
 713         /*
 714          * This resurrects the belts and suspenders paranoia check by HPA
 715          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 716          * does not do getcwd() based path canonicalization.
 717          *
 718          * sl becomes true immediately after seeing '/' and continues to
 719          * be true as long as dots continue after that without intervening
 720          * non-dot character.
 721          */
 722         if (!p || (*p != '/' && *p != '~'))
 723                 return -1;
 724         sl = 1; ndot = 0;
 725         p++;
 726
 727         while (1) {
 728                 char ch = *p++;
 729                 if (sl) {
 730                         if (ch == '.')
 731                                 ndot++;
 732                         else if (ch == '/') {
 733                                 if (ndot < 3)
 734                                         /* reject //, /./ and /../ */
 735                                         return -1;
 736                                 ndot = 0;
 737                         }
 738                         else if (ch == 0) {
 739                                 if (0 < ndot && ndot < 3)
 740                                         /* reject /.$ and /..$ */
 741                                         return -1;
 742                                 return 0;
 743                         }
 744                         else
 745                                 sl = ndot = 0;
 746                 }
 747                 else if (ch == 0)
 748                         return 0;
 749                 else if (ch == '/') {
 750                         sl = 1;
 751                         ndot = 0;
 752                 }
 753         }
 754 }
 755
 756 int offset_1st_component(const char *path)
 757 {
 758         if (has_dos_drive_prefix(path))
 759                 return 2 + is_dir_sep(path[2]);
 760         return is_dir_sep(path[0]);
 761 }