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