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) {
 152                 if (!xdg_home)
 153                         *xdg = NULL;
 154                 else
 155                         *xdg = mkpathdup("%s/git/%s", xdg_home, file);
 156         }
 157
 158         free(to_free);
 159 }
 160
 161 char *git_path_submodule(const char *path, const char *fmt, ...)
 162 {
 163         char *pathname = get_pathname();
 164         struct strbuf buf = STRBUF_INIT;
 165         const char *git_dir;
 166         va_list args;
 167         unsigned len;
 168
 169         len = strlen(path);
 170         if (len > PATH_MAX-100)
 171                 return bad_path;
 172
 173         strbuf_addstr(&buf, path);
 174         if (len && path[len-1] != '/')
 175                 strbuf_addch(&buf, '/');
 176         strbuf_addstr(&buf, ".git");
 177
 178         git_dir = read_gitfile(buf.buf);
 179         if (git_dir) {
 180                 strbuf_reset(&buf);
 181                 strbuf_addstr(&buf, git_dir);
 182         }
 183         strbuf_addch(&buf, '/');
 184
 185         if (buf.len >= PATH_MAX)
 186                 return bad_path;
 187         memcpy(pathname, buf.buf, buf.len + 1);
 188
 189         strbuf_release(&buf);
 190         len = strlen(pathname);
 191
 192         va_start(args, fmt);
 193         len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
 194         va_end(args);
 195         if (len >= PATH_MAX)
 196                 return bad_path;
 197         return cleanup_path(pathname);
 198 }
 199
 200 int validate_headref(const char *path)
 201 {
 202         struct stat st;
 203         char *buf, buffer[256];
 204         unsigned char sha1[20];
 205         int fd;
 206         ssize_t len;
 207
 208         if (lstat(path, &st) < 0)
 209                 return -1;
 210
 211         /* Make sure it is a "refs/.." symlink */
 212         if (S_ISLNK(st.st_mode)) {
 213                 len = readlink(path, buffer, sizeof(buffer)-1);
 214                 if (len >= 5 && !memcmp("refs/", buffer, 5))
 215                         return 0;
 216                 return -1;
 217         }
 218
 219         /*
 220          * Anything else, just open it and try to see if it is a symbolic ref.
 221          */
 222         fd = open(path, O_RDONLY);
 223         if (fd < 0)
 224                 return -1;
 225         len = read_in_full(fd, buffer, sizeof(buffer)-1);
 226         close(fd);
 227
 228         /*
 229          * Is it a symbolic ref?
 230          */
 231         if (len < 4)
 232                 return -1;
 233         if (!memcmp("ref:", buffer, 4)) {
 234                 buf = buffer + 4;
 235                 len -= 4;
 236                 while (len && isspace(*buf))
 237                         buf++, len--;
 238                 if (len >= 5 && !memcmp("refs/", buf, 5))
 239                         return 0;
 240         }
 241
 242         /*
 243          * Is this a detached HEAD?
 244          */
 245         if (!get_sha1_hex(buffer, sha1))
 246                 return 0;
 247
 248         return -1;
 249 }
 250
 251 static struct passwd *getpw_str(const char *username, size_t len)
 252 {
 253         struct passwd *pw;
 254         char *username_z = xmemdupz(username, len);
 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 *to_copy = path;
 269
 270         if (path == NULL)
 271                 goto return_null;
 272         if (path[0] == '~') {
 273                 const char *first_slash = strchrnul(path, '/');
 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_addstr(&user_path, home);
 281                 } else {
 282                         struct passwd *pw = getpw_str(username, username_len);
 283                         if (!pw)
 284                                 goto return_null;
 285                         strbuf_addstr(&user_path, pw->pw_dir);
 286                 }
 287                 to_copy = first_slash;
 288         }
 289         strbuf_addstr(&user_path, 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 check "%s/.git", "%s", "%s.git/.git", "%s.git"
 307  * in this order. We select the first one that is a valid git repository, and
 308  * chdir() to it. If none match, or we fail to chdir, we return NULL.
 309  *
 310  * If all goes well, we return the directory we used to chdir() (but
 311  * before ~user is expanded), avoiding getcwd() resolving symbolic
 312  * links.  User relative paths are also returned as they are given,
 313  * except DWIM suffixing.
 314  */
 315 const char *enter_repo(const char *path, int strict)
 316 {
 317         static char used_path[PATH_MAX];
 318         static char validated_path[PATH_MAX];
 319
 320         if (!path)
 321                 return NULL;
 322
 323         if (!strict) {
 324                 static const char *suffix[] = {
 325                         "/.git", "", ".git/.git", ".git", NULL,
 326                 };
 327                 const char *gitfile;
 328                 int len = strlen(path);
 329                 int i;
 330                 while ((1 < len) && (path[len-1] == '/'))
 331                         len--;
 332
 333                 if (PATH_MAX <= len)
 334                         return NULL;
 335                 strncpy(used_path, path, len); used_path[len] = 0 ;
 336                 strcpy(validated_path, used_path);
 337
 338                 if (used_path[0] == '~') {
 339                         char *newpath = expand_user_path(used_path);
 340                         if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
 341                                 free(newpath);
 342                                 return NULL;
 343                         }
 344                         /*
 345                          * Copy back into the static buffer. A pity
 346                          * since newpath was not bounded, but other
 347                          * branches of the if are limited by PATH_MAX
 348                          * anyway.
 349                          */
 350                         strcpy(used_path, newpath); free(newpath);
 351                 }
 352                 else if (PATH_MAX - 10 < len)
 353                         return NULL;
 354                 len = strlen(used_path);
 355                 for (i = 0; suffix[i]; i++) {
 356                         struct stat st;
 357                         strcpy(used_path + len, suffix[i]);
 358                         if (!stat(used_path, &st) &&
 359                             (S_ISREG(st.st_mode) ||
 360                             (S_ISDIR(st.st_mode) && is_git_directory(used_path)))) {
 361                                 strcat(validated_path, suffix[i]);
 362                                 break;
 363                         }
 364                 }
 365                 if (!suffix[i])
 366                         return NULL;
 367                 gitfile = read_gitfile(used_path) ;
 368                 if (gitfile)
 369                         strcpy(used_path, gitfile);
 370                 if (chdir(used_path))
 371                         return NULL;
 372                 path = validated_path;
 373         }
 374         else if (chdir(path))
 375                 return NULL;
 376
 377         if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
 378             validate_headref("HEAD") == 0) {
 379                 set_git_dir(".");
 380                 check_repository_format();
 381                 return path;
 382         }
 383
 384         return NULL;
 385 }
 386
 387 static int calc_shared_perm(int mode)
 388 {
 389         int tweak;
 390
 391         if (shared_repository < 0)
 392                 tweak = -shared_repository;
 393         else
 394                 tweak = shared_repository;
 395
 396         if (!(mode & S_IWUSR))
 397                 tweak &= ~0222;
 398         if (mode & S_IXUSR)
 399                 /* Copy read bits to execute bits */
 400                 tweak |= (tweak & 0444) >> 2;
 401         if (shared_repository < 0)
 402                 mode = (mode & ~0777) | tweak;
 403         else
 404                 mode |= tweak;
 405
 406         return mode;
 407 }
 408
 409
 410 int adjust_shared_perm(const char *path)
 411 {
 412         int old_mode, new_mode;
 413
 414         if (!shared_repository)
 415                 return 0;
 416         if (get_st_mode_bits(path, &old_mode) < 0)
 417                 return -1;
 418
 419         new_mode = calc_shared_perm(old_mode);
 420         if (S_ISDIR(old_mode)) {
 421                 /* Copy read bits to execute bits */
 422                 new_mode |= (new_mode & 0444) >> 2;
 423                 new_mode |= FORCE_DIR_SET_GID;
 424         }
 425
 426         if (((old_mode ^ new_mode) & ~S_IFMT) &&
 427                         chmod(path, (new_mode & ~S_IFMT)) < 0)
 428                 return -2;
 429         return 0;
 430 }
 431
 432 static int have_same_root(const char *path1, const char *path2)
 433 {
 434         int is_abs1, is_abs2;
 435
 436         is_abs1 = is_absolute_path(path1);
 437         is_abs2 = is_absolute_path(path2);
 438         return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 439                (!is_abs1 && !is_abs2);
 440 }
 441
 442 /*
 443  * Give path as relative to prefix.
 444  *
 445  * The strbuf may or may not be used, so do not assume it contains the
 446  * returned path.
 447  */
 448 const char *relative_path(const char *in, const char *prefix,
 449                           struct strbuf *sb)
 450 {
 451         int in_len = in ? strlen(in) : 0;
 452         int prefix_len = prefix ? strlen(prefix) : 0;
 453         int in_off = 0;
 454         int prefix_off = 0;
 455         int i = 0, j = 0;
 456
 457         if (!in_len)
 458                 return "./";
 459         else if (!prefix_len)
 460                 return in;
 461
 462         if (have_same_root(in, prefix)) {
 463                 /* bypass dos_drive, for "c:" is identical to "C:" */
 464                 if (has_dos_drive_prefix(in)) {
 465                         i = 2;
 466                         j = 2;
 467                 }
 468         } else {
 469                 return in;
 470         }
 471
 472         while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 473                 if (is_dir_sep(prefix[i])) {
 474                         while (is_dir_sep(prefix[i]))
 475                                 i++;
 476                         while (is_dir_sep(in[j]))
 477                                 j++;
 478                         prefix_off = i;
 479                         in_off = j;
 480                 } else {
 481                         i++;
 482                         j++;
 483                 }
 484         }
 485
 486         if (
 487             /* "prefix" seems like prefix of "in" */
 488             i >= prefix_len &&
 489             /*
 490              * but "/foo" is not a prefix of "/foobar"
 491              * (i.e. prefix not end with '/')
 492              */
 493             prefix_off < prefix_len) {
 494                 if (j >= in_len) {
 495                         /* in="/a/b", prefix="/a/b" */
 496                         in_off = in_len;
 497                 } else if (is_dir_sep(in[j])) {
 498                         /* in="/a/b/c", prefix="/a/b" */
 499                         while (is_dir_sep(in[j]))
 500                                 j++;
 501                         in_off = j;
 502                 } else {
 503                         /* in="/a/bbb/c", prefix="/a/b" */
 504                         i = prefix_off;
 505                 }
 506         } else if (
 507                    /* "in" is short than "prefix" */
 508                    j >= in_len &&
 509                    /* "in" not end with '/' */
 510                    in_off < in_len) {
 511                 if (is_dir_sep(prefix[i])) {
 512                         /* in="/a/b", prefix="/a/b/c/" */
 513                         while (is_dir_sep(prefix[i]))
 514                                 i++;
 515                         in_off = in_len;
 516                 }
 517         }
 518         in += in_off;
 519         in_len -= in_off;
 520
 521         if (i >= prefix_len) {
 522                 if (!in_len)
 523                         return "./";
 524                 else
 525                         return in;
 526         }
 527
 528         strbuf_reset(sb);
 529         strbuf_grow(sb, in_len);
 530
 531         while (i < prefix_len) {
 532                 if (is_dir_sep(prefix[i])) {
 533                         strbuf_addstr(sb, "../");
 534                         while (is_dir_sep(prefix[i]))
 535                                 i++;
 536                         continue;
 537                 }
 538                 i++;
 539         }
 540         if (!is_dir_sep(prefix[prefix_len - 1]))
 541                 strbuf_addstr(sb, "../");
 542
 543         strbuf_addstr(sb, in);
 544
 545         return sb->buf;
 546 }
 547
 548 /*
 549  * A simpler implementation of relative_path
 550  *
 551  * Get relative path by removing "prefix" from "in". This function
 552  * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
 553  * to increase performance when traversing the path to work_tree.
 554  */
 555 const char *remove_leading_path(const char *in, const char *prefix)
 556 {
 557         static char buf[PATH_MAX + 1];
 558         int i = 0, j = 0;
 559
 560         if (!prefix || !prefix[0])
 561                 return in;
 562         while (prefix[i]) {
 563                 if (is_dir_sep(prefix[i])) {
 564                         if (!is_dir_sep(in[j]))
 565                                 return in;
 566                         while (is_dir_sep(prefix[i]))
 567                                 i++;
 568                         while (is_dir_sep(in[j]))
 569                                 j++;
 570                         continue;
 571                 } else if (in[j] != prefix[i]) {
 572                         return in;
 573                 }
 574                 i++;
 575                 j++;
 576         }
 577         if (
 578             /* "/foo" is a prefix of "/foo" */
 579             in[j] &&
 580             /* "/foo" is not a prefix of "/foobar" */
 581             !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
 582            )
 583                 return in;
 584         while (is_dir_sep(in[j]))
 585                 j++;
 586         if (!in[j])
 587                 strcpy(buf, ".");
 588         else
 589                 strcpy(buf, in + j);
 590         return buf;
 591 }
 592
 593 /*
 594  * It is okay if dst == src, but they should not overlap otherwise.
 595  *
 596  * Performs the following normalizations on src, storing the result in dst:
 597  * - Ensures that components are separated by '/' (Windows only)
 598  * - Squashes sequences of '/'.
 599  * - Removes "." components.
 600  * - Removes ".." components, and the components the precede them.
 601  * Returns failure (non-zero) if a ".." component appears as first path
 602  * component anytime during the normalization. Otherwise, returns success (0).
 603  *
 604  * Note that this function is purely textual.  It does not follow symlinks,
 605  * verify the existence of the path, or make any system calls.
 606  *
 607  * prefix_len != NULL is for a specific case of prefix_pathspec():
 608  * assume that src == dst and src[0..prefix_len-1] is already
 609  * normalized, any time "../" eats up to the prefix_len part,
 610  * prefix_len is reduced. In the end prefix_len is the remaining
 611  * prefix that has not been overridden by user pathspec.
 612  */
 613 int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
 614 {
 615         char *dst0;
 616
 617         if (has_dos_drive_prefix(src)) {
 618                 *dst++ = *src++;
 619                 *dst++ = *src++;
 620         }
 621         dst0 = dst;
 622
 623         if (is_dir_sep(*src)) {
 624                 *dst++ = '/';
 625                 while (is_dir_sep(*src))
 626                         src++;
 627         }
 628
 629         for (;;) {
 630                 char c = *src;
 631
 632                 /*
 633                  * A path component that begins with . could be
 634                  * special:
 635                  * (1) "." and ends   -- ignore and terminate.
 636                  * (2) "./"           -- ignore them, eat slash and continue.
 637                  * (3) ".." and ends  -- strip one and terminate.
 638                  * (4) "../"          -- strip one, eat slash and continue.
 639                  */
 640                 if (c == '.') {
 641                         if (!src[1]) {
 642                                 /* (1) */
 643                                 src++;
 644                         } else if (is_dir_sep(src[1])) {
 645                                 /* (2) */
 646                                 src += 2;
 647                                 while (is_dir_sep(*src))
 648                                         src++;
 649                                 continue;
 650                         } else if (src[1] == '.') {
 651                                 if (!src[2]) {
 652                                         /* (3) */
 653                                         src += 2;
 654                                         goto up_one;
 655                                 } else if (is_dir_sep(src[2])) {
 656                                         /* (4) */
 657                                         src += 3;
 658                                         while (is_dir_sep(*src))
 659                                                 src++;
 660                                         goto up_one;
 661                                 }
 662                         }
 663                 }
 664
 665                 /* copy up to the next '/', and eat all '/' */
 666                 while ((c = *src++) != '\0' && !is_dir_sep(c))
 667                         *dst++ = c;
 668                 if (is_dir_sep(c)) {
 669                         *dst++ = '/';
 670                         while (is_dir_sep(c))
 671                                 c = *src++;
 672                         src--;
 673                 } else if (!c)
 674                         break;
 675                 continue;
 676
 677         up_one:
 678                 /*
 679                  * dst0..dst is prefix portion, and dst[-1] is '/';
 680                  * go up one level.
 681                  */
 682                 dst--;  /* go to trailing '/' */
 683                 if (dst <= dst0)
 684                         return -1;
 685                 /* Windows: dst[-1] cannot be backslash anymore */
 686                 while (dst0 < dst && dst[-1] != '/')
 687                         dst--;
 688                 if (prefix_len && *prefix_len > dst - dst0)
 689                         *prefix_len = dst - dst0;
 690         }
 691         *dst = '\0';
 692         return 0;
 693 }
 694
 695 int normalize_path_copy(char *dst, const char *src)
 696 {
 697         return normalize_path_copy_len(dst, src, NULL);
 698 }
 699
 700 /*
 701  * path = Canonical absolute path
 702  * prefixes = string_list containing normalized, absolute paths without
 703  * trailing slashes (except for the root directory, which is denoted by "/").
 704  *
 705  * Determines, for each path in prefixes, whether the "prefix"
 706  * is an ancestor directory of path.  Returns the length of the longest
 707  * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 708  * is an ancestor.  (Note that this means 0 is returned if prefixes is
 709  * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
 710  * are not considered to be their own ancestors.  path must be in a
 711  * canonical form: empty components, or "." or ".." components are not
 712  * allowed.
 713  */
 714 int longest_ancestor_length(const char *path, struct string_list *prefixes)
 715 {
 716         int i, max_len = -1;
 717
 718         if (!strcmp(path, "/"))
 719                 return -1;
 720
 721         for (i = 0; i < prefixes->nr; i++) {
 722                 const char *ceil = prefixes->items[i].string;
 723                 int len = strlen(ceil);
 724
 725                 if (len == 1 && ceil[0] == '/')
 726                         len = 0; /* root matches anything, with length 0 */
 727                 else if (!strncmp(path, ceil, len) && path[len] == '/')
 728                         ; /* match of length len */
 729                 else
 730                         continue; /* no match */
 731
 732                 if (len > max_len)
 733                         max_len = len;
 734         }
 735
 736         return max_len;
 737 }
 738
 739 /* strip arbitrary amount of directory separators at end of path */
 740 static inline int chomp_trailing_dir_sep(const char *path, int len)
 741 {
 742         while (len && is_dir_sep(path[len - 1]))
 743                 len--;
 744         return len;
 745 }
 746
 747 /*
 748  * If path ends with suffix (complete path components), returns the
 749  * part before suffix (sans trailing directory separators).
 750  * Otherwise returns NULL.
 751  */
 752 char *strip_path_suffix(const char *path, const char *suffix)
 753 {
 754         int path_len = strlen(path), suffix_len = strlen(suffix);
 755
 756         while (suffix_len) {
 757                 if (!path_len)
 758                         return NULL;
 759
 760                 if (is_dir_sep(path[path_len - 1])) {
 761                         if (!is_dir_sep(suffix[suffix_len - 1]))
 762                                 return NULL;
 763                         path_len = chomp_trailing_dir_sep(path, path_len);
 764                         suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 765                 }
 766                 else if (path[--path_len] != suffix[--suffix_len])
 767                         return NULL;
 768         }
 769
 770         if (path_len && !is_dir_sep(path[path_len - 1]))
 771                 return NULL;
 772         return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
 773 }
 774
 775 int daemon_avoid_alias(const char *p)
 776 {
 777         int sl, ndot;
 778
 779         /*
 780          * This resurrects the belts and suspenders paranoia check by HPA
 781          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 782          * does not do getcwd() based path canonicalization.
 783          *
 784          * sl becomes true immediately after seeing '/' and continues to
 785          * be true as long as dots continue after that without intervening
 786          * non-dot character.
 787          */
 788         if (!p || (*p != '/' && *p != '~'))
 789                 return -1;
 790         sl = 1; ndot = 0;
 791         p++;
 792
 793         while (1) {
 794                 char ch = *p++;
 795                 if (sl) {
 796                         if (ch == '.')
 797                                 ndot++;
 798                         else if (ch == '/') {
 799                                 if (ndot < 3)
 800                                         /* reject //, /./ and /../ */
 801                                         return -1;
 802                                 ndot = 0;
 803                         }
 804                         else if (ch == 0) {
 805                                 if (0 < ndot && ndot < 3)
 806                                         /* reject /.$ and /..$ */
 807                                         return -1;
 808                                 return 0;
 809                         }
 810                         else
 811                                 sl = ndot = 0;
 812                 }
 813                 else if (ch == 0)
 814                         return 0;
 815                 else if (ch == '/') {
 816                         sl = 1;
 817                         ndot = 0;
 818                 }
 819         }
 820 }
 821
 822 static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
 823 {
 824         if (len < skip)
 825                 return 0;
 826         len -= skip;
 827         path += skip;
 828         while (len-- > 0) {
 829                 char c = *(path++);
 830                 if (c != ' ' && c != '.')
 831                         return 0;
 832         }
 833         return 1;
 834 }
 835
 836 int is_ntfs_dotgit(const char *name)
 837 {
 838         int len;
 839
 840         for (len = 0; ; len++)
 841                 if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
 842                         if (only_spaces_and_periods(name, len, 4) &&
 843                                         !strncasecmp(name, ".git", 4))
 844                                 return 1;
 845                         if (only_spaces_and_periods(name, len, 5) &&
 846                                         !strncasecmp(name, "git~1", 5))
 847                                 return 1;
 848                         if (name[len] != '\\')
 849                                 return 0;
 850                         name += len + 1;
 851                         len = -1;
 852                 }
 853 }