path.c

   1 /*
   2  * Utilities for paths and pathnames
   3  */
   4 #include "cache.h"
   5 #include "strbuf.h"
   6 #include "string-list.h"
   7 #include "dir.h"
   8
   9 static int get_st_mode_bits(const char *path, int *mode)
  10 {
  11         struct stat st;
  12         if (lstat(path, &st) < 0)
  13                 return -1;
  14         *mode = st.st_mode;
  15         return 0;
  16 }
  17
  18 static char bad_path[] = "/bad-path/";
  19
  20 static struct strbuf *get_pathname(void)
  21 {
  22         static struct strbuf pathname_array[4] = {
  23                 STRBUF_INIT, STRBUF_INIT, STRBUF_INIT, STRBUF_INIT
  24         };
  25         static int index;
  26         struct strbuf *sb = &pathname_array[3 & ++index];
  27         strbuf_reset(sb);
  28         return sb;
  29 }
  30
  31 static char *cleanup_path(char *path)
  32 {
  33         /* Clean it up */
  34         if (!memcmp(path, "./", 2)) {
  35                 path += 2;
  36                 while (*path == '/')
  37                         path++;
  38         }
  39         return path;
  40 }
  41
  42 static void strbuf_cleanup_path(struct strbuf *sb)
  43 {
  44         char *path = cleanup_path(sb->buf);
  45         if (path > sb->buf)
  46                 strbuf_remove(sb, 0, path - sb->buf);
  47 }
  48
  49 char *mksnpath(char *buf, size_t n, const char *fmt, ...)
  50 {
  51         va_list args;
  52         unsigned len;
  53
  54         va_start(args, fmt);
  55         len = vsnprintf(buf, n, fmt, args);
  56         va_end(args);
  57         if (len >= n) {
  58                 strlcpy(buf, bad_path, n);
  59                 return buf;
  60         }
  61         return cleanup_path(buf);
  62 }
  63
  64 static int dir_prefix(const char *buf, const char *dir)
  65 {
  66         int len = strlen(dir);
  67         return !strncmp(buf, dir, len) &&
  68                 (is_dir_sep(buf[len]) || buf[len] == '\0');
  69 }
  70
  71 /* $buf =~ m|$dir/+$file| but without regex */
  72 static int is_dir_file(const char *buf, const char *dir, const char *file)
  73 {
  74         int len = strlen(dir);
  75         if (strncmp(buf, dir, len) || !is_dir_sep(buf[len]))
  76                 return 0;
  77         while (is_dir_sep(buf[len]))
  78                 len++;
  79         return !strcmp(buf + len, file);
  80 }
  81
  82 static void replace_dir(struct strbuf *buf, int len, const char *newdir)
  83 {
  84         int newlen = strlen(newdir);
  85         int need_sep = (buf->buf[len] && !is_dir_sep(buf->buf[len])) &&
  86                 !is_dir_sep(newdir[newlen - 1]);
  87         if (need_sep)
  88                 len--;   /* keep one char, to be replaced with '/'  */
  89         strbuf_splice(buf, 0, len, newdir, newlen);
  90         if (need_sep)
  91                 buf->buf[newlen] = '/';
  92 }
  93
  94 static const char *common_list[] = {
  95         "/branches", "/hooks", "/info", "!/logs", "/lost-found",
  96         "/objects", "/refs", "/remotes", "/worktrees", "/rr-cache", "/svn",
  97         "config", "!gc.pid", "packed-refs", "shallow",
  98         NULL
  99 };
 100
 101 static void update_common_dir(struct strbuf *buf, int git_dir_len)
 102 {
 103         char *base = buf->buf + git_dir_len;
 104         const char **p;
 105
 106         if (is_dir_file(base, "logs", "HEAD") ||
 107             is_dir_file(base, "info", "sparse-checkout"))
 108                 return; /* keep this in $GIT_DIR */
 109         for (p = common_list; *p; p++) {
 110                 const char *path = *p;
 111                 int is_dir = 0;
 112                 if (*path == '!')
 113                         path++;
 114                 if (*path == '/') {
 115                         path++;
 116                         is_dir = 1;
 117                 }
 118                 if (is_dir && dir_prefix(base, path)) {
 119                         replace_dir(buf, git_dir_len, get_git_common_dir());
 120                         return;
 121                 }
 122                 if (!is_dir && !strcmp(base, path)) {
 123                         replace_dir(buf, git_dir_len, get_git_common_dir());
 124                         return;
 125                 }
 126         }
 127 }
 128
 129 void report_linked_checkout_garbage(void)
 130 {
 131         struct strbuf sb = STRBUF_INIT;
 132         const char **p;
 133         int len;
 134
 135         if (!git_common_dir_env)
 136                 return;
 137         strbuf_addf(&sb, "%s/", get_git_dir());
 138         len = sb.len;
 139         for (p = common_list; *p; p++) {
 140                 const char *path = *p;
 141                 if (*path == '!')
 142                         continue;
 143                 strbuf_setlen(&sb, len);
 144                 strbuf_addstr(&sb, path);
 145                 if (file_exists(sb.buf))
 146                         report_garbage("unused in linked checkout", sb.buf);
 147         }
 148         strbuf_release(&sb);
 149 }
 150
 151 static void adjust_git_path(struct strbuf *buf, int git_dir_len)
 152 {
 153         const char *base = buf->buf + git_dir_len;
 154         if (git_graft_env && is_dir_file(base, "info", "grafts"))
 155                 strbuf_splice(buf, 0, buf->len,
 156                               get_graft_file(), strlen(get_graft_file()));
 157         else if (git_index_env && !strcmp(base, "index"))
 158                 strbuf_splice(buf, 0, buf->len,
 159                               get_index_file(), strlen(get_index_file()));
 160         else if (git_db_env && dir_prefix(base, "objects"))
 161                 replace_dir(buf, git_dir_len + 7, get_object_directory());
 162         else if (git_common_dir_env)
 163                 update_common_dir(buf, git_dir_len);
 164 }
 165
 166 static void do_git_path(struct strbuf *buf, const char *fmt, va_list args)
 167 {
 168         int gitdir_len;
 169         strbuf_addstr(buf, get_git_dir());
 170         if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 171                 strbuf_addch(buf, '/');
 172         gitdir_len = buf->len;
 173         strbuf_vaddf(buf, fmt, args);
 174         adjust_git_path(buf, gitdir_len);
 175         strbuf_cleanup_path(buf);
 176 }
 177
 178 void strbuf_git_path(struct strbuf *sb, const char *fmt, ...)
 179 {
 180         va_list args;
 181         va_start(args, fmt);
 182         do_git_path(sb, fmt, args);
 183         va_end(args);
 184 }
 185
 186 const char *git_path(const char *fmt, ...)
 187 {
 188         struct strbuf *pathname = get_pathname();
 189         va_list args;
 190         va_start(args, fmt);
 191         do_git_path(pathname, fmt, args);
 192         va_end(args);
 193         return pathname->buf;
 194 }
 195
 196 char *git_pathdup(const char *fmt, ...)
 197 {
 198         struct strbuf path = STRBUF_INIT;
 199         va_list args;
 200         va_start(args, fmt);
 201         do_git_path(&path, fmt, args);
 202         va_end(args);
 203         return strbuf_detach(&path, NULL);
 204 }
 205
 206 char *mkpathdup(const char *fmt, ...)
 207 {
 208         struct strbuf sb = STRBUF_INIT;
 209         va_list args;
 210         va_start(args, fmt);
 211         strbuf_vaddf(&sb, fmt, args);
 212         va_end(args);
 213         strbuf_cleanup_path(&sb);
 214         return strbuf_detach(&sb, NULL);
 215 }
 216
 217 const char *mkpath(const char *fmt, ...)
 218 {
 219         va_list args;
 220         struct strbuf *pathname = get_pathname();
 221         va_start(args, fmt);
 222         strbuf_vaddf(pathname, fmt, args);
 223         va_end(args);
 224         return cleanup_path(pathname->buf);
 225 }
 226
 227 const char *git_path_submodule(const char *path, const char *fmt, ...)
 228 {
 229         struct strbuf *buf = get_pathname();
 230         const char *git_dir;
 231         va_list args;
 232
 233         strbuf_addstr(buf, path);
 234         if (buf->len && buf->buf[buf->len - 1] != '/')
 235                 strbuf_addch(buf, '/');
 236         strbuf_addstr(buf, ".git");
 237
 238         git_dir = read_gitfile(buf->buf);
 239         if (git_dir) {
 240                 strbuf_reset(buf);
 241                 strbuf_addstr(buf, git_dir);
 242         }
 243         strbuf_addch(buf, '/');
 244
 245         va_start(args, fmt);
 246         strbuf_vaddf(buf, fmt, args);
 247         va_end(args);
 248         strbuf_cleanup_path(buf);
 249         return buf->buf;
 250 }
 251
 252 int validate_headref(const char *path)
 253 {
 254         struct stat st;
 255         char *buf, buffer[256];
 256         unsigned char sha1[20];
 257         int fd;
 258         ssize_t len;
 259
 260         if (lstat(path, &st) < 0)
 261                 return -1;
 262
 263         /* Make sure it is a "refs/.." symlink */
 264         if (S_ISLNK(st.st_mode)) {
 265                 len = readlink(path, buffer, sizeof(buffer)-1);
 266                 if (len >= 5 && !memcmp("refs/", buffer, 5))
 267                         return 0;
 268                 return -1;
 269         }
 270
 271         /*
 272          * Anything else, just open it and try to see if it is a symbolic ref.
 273          */
 274         fd = open(path, O_RDONLY);
 275         if (fd < 0)
 276                 return -1;
 277         len = read_in_full(fd, buffer, sizeof(buffer)-1);
 278         close(fd);
 279
 280         /*
 281          * Is it a symbolic ref?
 282          */
 283         if (len < 4)
 284                 return -1;
 285         if (!memcmp("ref:", buffer, 4)) {
 286                 buf = buffer + 4;
 287                 len -= 4;
 288                 while (len && isspace(*buf))
 289                         buf++, len--;
 290                 if (len >= 5 && !memcmp("refs/", buf, 5))
 291                         return 0;
 292         }
 293
 294         /*
 295          * Is this a detached HEAD?
 296          */
 297         if (!get_sha1_hex(buffer, sha1))
 298                 return 0;
 299
 300         return -1;
 301 }
 302
 303 static struct passwd *getpw_str(const char *username, size_t len)
 304 {
 305         struct passwd *pw;
 306         char *username_z = xmemdupz(username, len);
 307         pw = getpwnam(username_z);
 308         free(username_z);
 309         return pw;
 310 }
 311
 312 /*
 313  * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 314  * then it is a newly allocated string. Returns NULL on getpw failure or
 315  * if path is NULL.
 316  */
 317 char *expand_user_path(const char *path)
 318 {
 319         struct strbuf user_path = STRBUF_INIT;
 320         const char *to_copy = path;
 321
 322         if (path == NULL)
 323                 goto return_null;
 324         if (path[0] == '~') {
 325                 const char *first_slash = strchrnul(path, '/');
 326                 const char *username = path + 1;
 327                 size_t username_len = first_slash - username;
 328                 if (username_len == 0) {
 329                         const char *home = getenv("HOME");
 330                         if (!home)
 331                                 goto return_null;
 332                         strbuf_addstr(&user_path, home);
 333                 } else {
 334                         struct passwd *pw = getpw_str(username, username_len);
 335                         if (!pw)
 336                                 goto return_null;
 337                         strbuf_addstr(&user_path, pw->pw_dir);
 338                 }
 339                 to_copy = first_slash;
 340         }
 341         strbuf_addstr(&user_path, to_copy);
 342         return strbuf_detach(&user_path, NULL);
 343 return_null:
 344         strbuf_release(&user_path);
 345         return NULL;
 346 }
 347
 348 /*
 349  * First, one directory to try is determined by the following algorithm.
 350  *
 351  * (0) If "strict" is given, the path is used as given and no DWIM is
 352  *     done. Otherwise:
 353  * (1) "~/path" to mean path under the running user's home directory;
 354  * (2) "~user/path" to mean path under named user's home directory;
 355  * (3) "relative/path" to mean cwd relative directory; or
 356  * (4) "/absolute/path" to mean absolute directory.
 357  *
 358  * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
 359  * in this order. We select the first one that is a valid git repository, and
 360  * chdir() to it. If none match, or we fail to chdir, we return NULL.
 361  *
 362  * If all goes well, we return the directory we used to chdir() (but
 363  * before ~user is expanded), avoiding getcwd() resolving symbolic
 364  * links.  User relative paths are also returned as they are given,
 365  * except DWIM suffixing.
 366  */
 367 const char *enter_repo(const char *path, int strict)
 368 {
 369         static char used_path[PATH_MAX];
 370         static char validated_path[PATH_MAX];
 371
 372         if (!path)
 373                 return NULL;
 374
 375         if (!strict) {
 376                 static const char *suffix[] = {
 377                         "/.git", "", ".git/.git", ".git", NULL,
 378                 };
 379                 const char *gitfile;
 380                 int len = strlen(path);
 381                 int i;
 382                 while ((1 < len) && (path[len-1] == '/'))
 383                         len--;
 384
 385                 if (PATH_MAX <= len)
 386                         return NULL;
 387                 strncpy(used_path, path, len); used_path[len] = 0 ;
 388                 strcpy(validated_path, used_path);
 389
 390                 if (used_path[0] == '~') {
 391                         char *newpath = expand_user_path(used_path);
 392                         if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
 393                                 free(newpath);
 394                                 return NULL;
 395                         }
 396                         /*
 397                          * Copy back into the static buffer. A pity
 398                          * since newpath was not bounded, but other
 399                          * branches of the if are limited by PATH_MAX
 400                          * anyway.
 401                          */
 402                         strcpy(used_path, newpath); free(newpath);
 403                 }
 404                 else if (PATH_MAX - 10 < len)
 405                         return NULL;
 406                 len = strlen(used_path);
 407                 for (i = 0; suffix[i]; i++) {
 408                         struct stat st;
 409                         strcpy(used_path + len, suffix[i]);
 410                         if (!stat(used_path, &st) &&
 411                             (S_ISREG(st.st_mode) ||
 412                             (S_ISDIR(st.st_mode) && is_git_directory(used_path)))) {
 413                                 strcat(validated_path, suffix[i]);
 414                                 break;
 415                         }
 416                 }
 417                 if (!suffix[i])
 418                         return NULL;
 419                 gitfile = read_gitfile(used_path) ;
 420                 if (gitfile)
 421                         strcpy(used_path, gitfile);
 422                 if (chdir(used_path))
 423                         return NULL;
 424                 path = validated_path;
 425         }
 426         else if (chdir(path))
 427                 return NULL;
 428
 429         if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
 430             validate_headref("HEAD") == 0) {
 431                 set_git_dir(".");
 432                 check_repository_format();
 433                 return path;
 434         }
 435
 436         return NULL;
 437 }
 438
 439 static int calc_shared_perm(int mode)
 440 {
 441         int tweak;
 442
 443         if (shared_repository < 0)
 444                 tweak = -shared_repository;
 445         else
 446                 tweak = shared_repository;
 447
 448         if (!(mode & S_IWUSR))
 449                 tweak &= ~0222;
 450         if (mode & S_IXUSR)
 451                 /* Copy read bits to execute bits */
 452                 tweak |= (tweak & 0444) >> 2;
 453         if (shared_repository < 0)
 454                 mode = (mode & ~0777) | tweak;
 455         else
 456                 mode |= tweak;
 457
 458         return mode;
 459 }
 460
 461
 462 int adjust_shared_perm(const char *path)
 463 {
 464         int old_mode, new_mode;
 465
 466         if (!shared_repository)
 467                 return 0;
 468         if (get_st_mode_bits(path, &old_mode) < 0)
 469                 return -1;
 470
 471         new_mode = calc_shared_perm(old_mode);
 472         if (S_ISDIR(old_mode)) {
 473                 /* Copy read bits to execute bits */
 474                 new_mode |= (new_mode & 0444) >> 2;
 475                 new_mode |= FORCE_DIR_SET_GID;
 476         }
 477
 478         if (((old_mode ^ new_mode) & ~S_IFMT) &&
 479                         chmod(path, (new_mode & ~S_IFMT)) < 0)
 480                 return -2;
 481         return 0;
 482 }
 483
 484 static int have_same_root(const char *path1, const char *path2)
 485 {
 486         int is_abs1, is_abs2;
 487
 488         is_abs1 = is_absolute_path(path1);
 489         is_abs2 = is_absolute_path(path2);
 490         return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 491                (!is_abs1 && !is_abs2);
 492 }
 493
 494 /*
 495  * Give path as relative to prefix.
 496  *
 497  * The strbuf may or may not be used, so do not assume it contains the
 498  * returned path.
 499  */
 500 const char *relative_path(const char *in, const char *prefix,
 501                           struct strbuf *sb)
 502 {
 503         int in_len = in ? strlen(in) : 0;
 504         int prefix_len = prefix ? strlen(prefix) : 0;
 505         int in_off = 0;
 506         int prefix_off = 0;
 507         int i = 0, j = 0;
 508
 509         if (!in_len)
 510                 return "./";
 511         else if (!prefix_len)
 512                 return in;
 513
 514         if (have_same_root(in, prefix)) {
 515                 /* bypass dos_drive, for "c:" is identical to "C:" */
 516                 if (has_dos_drive_prefix(in)) {
 517                         i = 2;
 518                         j = 2;
 519                 }
 520         } else {
 521                 return in;
 522         }
 523
 524         while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 525                 if (is_dir_sep(prefix[i])) {
 526                         while (is_dir_sep(prefix[i]))
 527                                 i++;
 528                         while (is_dir_sep(in[j]))
 529                                 j++;
 530                         prefix_off = i;
 531                         in_off = j;
 532                 } else {
 533                         i++;
 534                         j++;
 535                 }
 536         }
 537
 538         if (
 539             /* "prefix" seems like prefix of "in" */
 540             i >= prefix_len &&
 541             /*
 542              * but "/foo" is not a prefix of "/foobar"
 543              * (i.e. prefix not end with '/')
 544              */
 545             prefix_off < prefix_len) {
 546                 if (j >= in_len) {
 547                         /* in="/a/b", prefix="/a/b" */
 548                         in_off = in_len;
 549                 } else if (is_dir_sep(in[j])) {
 550                         /* in="/a/b/c", prefix="/a/b" */
 551                         while (is_dir_sep(in[j]))
 552                                 j++;
 553                         in_off = j;
 554                 } else {
 555                         /* in="/a/bbb/c", prefix="/a/b" */
 556                         i = prefix_off;
 557                 }
 558         } else if (
 559                    /* "in" is short than "prefix" */
 560                    j >= in_len &&
 561                    /* "in" not end with '/' */
 562                    in_off < in_len) {
 563                 if (is_dir_sep(prefix[i])) {
 564                         /* in="/a/b", prefix="/a/b/c/" */
 565                         while (is_dir_sep(prefix[i]))
 566                                 i++;
 567                         in_off = in_len;
 568                 }
 569         }
 570         in += in_off;
 571         in_len -= in_off;
 572
 573         if (i >= prefix_len) {
 574                 if (!in_len)
 575                         return "./";
 576                 else
 577                         return in;
 578         }
 579
 580         strbuf_reset(sb);
 581         strbuf_grow(sb, in_len);
 582
 583         while (i < prefix_len) {
 584                 if (is_dir_sep(prefix[i])) {
 585                         strbuf_addstr(sb, "../");
 586                         while (is_dir_sep(prefix[i]))
 587                                 i++;
 588                         continue;
 589                 }
 590                 i++;
 591         }
 592         if (!is_dir_sep(prefix[prefix_len - 1]))
 593                 strbuf_addstr(sb, "../");
 594
 595         strbuf_addstr(sb, in);
 596
 597         return sb->buf;
 598 }
 599
 600 /*
 601  * A simpler implementation of relative_path
 602  *
 603  * Get relative path by removing "prefix" from "in". This function
 604  * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
 605  * to increase performance when traversing the path to work_tree.
 606  */
 607 const char *remove_leading_path(const char *in, const char *prefix)
 608 {
 609         static char buf[PATH_MAX + 1];
 610         int i = 0, j = 0;
 611
 612         if (!prefix || !prefix[0])
 613                 return in;
 614         while (prefix[i]) {
 615                 if (is_dir_sep(prefix[i])) {
 616                         if (!is_dir_sep(in[j]))
 617                                 return in;
 618                         while (is_dir_sep(prefix[i]))
 619                                 i++;
 620                         while (is_dir_sep(in[j]))
 621                                 j++;
 622                         continue;
 623                 } else if (in[j] != prefix[i]) {
 624                         return in;
 625                 }
 626                 i++;
 627                 j++;
 628         }
 629         if (
 630             /* "/foo" is a prefix of "/foo" */
 631             in[j] &&
 632             /* "/foo" is not a prefix of "/foobar" */
 633             !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
 634            )
 635                 return in;
 636         while (is_dir_sep(in[j]))
 637                 j++;
 638         if (!in[j])
 639                 strcpy(buf, ".");
 640         else
 641                 strcpy(buf, in + j);
 642         return buf;
 643 }
 644
 645 /*
 646  * It is okay if dst == src, but they should not overlap otherwise.
 647  *
 648  * Performs the following normalizations on src, storing the result in dst:
 649  * - Ensures that components are separated by '/' (Windows only)
 650  * - Squashes sequences of '/'.
 651  * - Removes "." components.
 652  * - Removes ".." components, and the components the precede them.
 653  * Returns failure (non-zero) if a ".." component appears as first path
 654  * component anytime during the normalization. Otherwise, returns success (0).
 655  *
 656  * Note that this function is purely textual.  It does not follow symlinks,
 657  * verify the existence of the path, or make any system calls.
 658  *
 659  * prefix_len != NULL is for a specific case of prefix_pathspec():
 660  * assume that src == dst and src[0..prefix_len-1] is already
 661  * normalized, any time "../" eats up to the prefix_len part,
 662  * prefix_len is reduced. In the end prefix_len is the remaining
 663  * prefix that has not been overridden by user pathspec.
 664  */
 665 int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
 666 {
 667         char *dst0;
 668
 669         if (has_dos_drive_prefix(src)) {
 670                 *dst++ = *src++;
 671                 *dst++ = *src++;
 672         }
 673         dst0 = dst;
 674
 675         if (is_dir_sep(*src)) {
 676                 *dst++ = '/';
 677                 while (is_dir_sep(*src))
 678                         src++;
 679         }
 680
 681         for (;;) {
 682                 char c = *src;
 683
 684                 /*
 685                  * A path component that begins with . could be
 686                  * special:
 687                  * (1) "." and ends   -- ignore and terminate.
 688                  * (2) "./"           -- ignore them, eat slash and continue.
 689                  * (3) ".." and ends  -- strip one and terminate.
 690                  * (4) "../"          -- strip one, eat slash and continue.
 691                  */
 692                 if (c == '.') {
 693                         if (!src[1]) {
 694                                 /* (1) */
 695                                 src++;
 696                         } else if (is_dir_sep(src[1])) {
 697                                 /* (2) */
 698                                 src += 2;
 699                                 while (is_dir_sep(*src))
 700                                         src++;
 701                                 continue;
 702                         } else if (src[1] == '.') {
 703                                 if (!src[2]) {
 704                                         /* (3) */
 705                                         src += 2;
 706                                         goto up_one;
 707                                 } else if (is_dir_sep(src[2])) {
 708                                         /* (4) */
 709                                         src += 3;
 710                                         while (is_dir_sep(*src))
 711                                                 src++;
 712                                         goto up_one;
 713                                 }
 714                         }
 715                 }
 716
 717                 /* copy up to the next '/', and eat all '/' */
 718                 while ((c = *src++) != '\0' && !is_dir_sep(c))
 719                         *dst++ = c;
 720                 if (is_dir_sep(c)) {
 721                         *dst++ = '/';
 722                         while (is_dir_sep(c))
 723                                 c = *src++;
 724                         src--;
 725                 } else if (!c)
 726                         break;
 727                 continue;
 728
 729         up_one:
 730                 /*
 731                  * dst0..dst is prefix portion, and dst[-1] is '/';
 732                  * go up one level.
 733                  */
 734                 dst--;  /* go to trailing '/' */
 735                 if (dst <= dst0)
 736                         return -1;
 737                 /* Windows: dst[-1] cannot be backslash anymore */
 738                 while (dst0 < dst && dst[-1] != '/')
 739                         dst--;
 740                 if (prefix_len && *prefix_len > dst - dst0)
 741                         *prefix_len = dst - dst0;
 742         }
 743         *dst = '\0';
 744         return 0;
 745 }
 746
 747 int normalize_path_copy(char *dst, const char *src)
 748 {
 749         return normalize_path_copy_len(dst, src, NULL);
 750 }
 751
 752 /*
 753  * path = Canonical absolute path
 754  * prefixes = string_list containing normalized, absolute paths without
 755  * trailing slashes (except for the root directory, which is denoted by "/").
 756  *
 757  * Determines, for each path in prefixes, whether the "prefix"
 758  * is an ancestor directory of path.  Returns the length of the longest
 759  * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 760  * is an ancestor.  (Note that this means 0 is returned if prefixes is
 761  * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
 762  * are not considered to be their own ancestors.  path must be in a
 763  * canonical form: empty components, or "." or ".." components are not
 764  * allowed.
 765  */
 766 int longest_ancestor_length(const char *path, struct string_list *prefixes)
 767 {
 768         int i, max_len = -1;
 769
 770         if (!strcmp(path, "/"))
 771                 return -1;
 772
 773         for (i = 0; i < prefixes->nr; i++) {
 774                 const char *ceil = prefixes->items[i].string;
 775                 int len = strlen(ceil);
 776
 777                 if (len == 1 && ceil[0] == '/')
 778                         len = 0; /* root matches anything, with length 0 */
 779                 else if (!strncmp(path, ceil, len) && path[len] == '/')
 780                         ; /* match of length len */
 781                 else
 782                         continue; /* no match */
 783
 784                 if (len > max_len)
 785                         max_len = len;
 786         }
 787
 788         return max_len;
 789 }
 790
 791 /* strip arbitrary amount of directory separators at end of path */
 792 static inline int chomp_trailing_dir_sep(const char *path, int len)
 793 {
 794         while (len && is_dir_sep(path[len - 1]))
 795                 len--;
 796         return len;
 797 }
 798
 799 /*
 800  * If path ends with suffix (complete path components), returns the
 801  * part before suffix (sans trailing directory separators).
 802  * Otherwise returns NULL.
 803  */
 804 char *strip_path_suffix(const char *path, const char *suffix)
 805 {
 806         int path_len = strlen(path), suffix_len = strlen(suffix);
 807
 808         while (suffix_len) {
 809                 if (!path_len)
 810                         return NULL;
 811
 812                 if (is_dir_sep(path[path_len - 1])) {
 813                         if (!is_dir_sep(suffix[suffix_len - 1]))
 814                                 return NULL;
 815                         path_len = chomp_trailing_dir_sep(path, path_len);
 816                         suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 817                 }
 818                 else if (path[--path_len] != suffix[--suffix_len])
 819                         return NULL;
 820         }
 821
 822         if (path_len && !is_dir_sep(path[path_len - 1]))
 823                 return NULL;
 824         return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
 825 }
 826
 827 int daemon_avoid_alias(const char *p)
 828 {
 829         int sl, ndot;
 830
 831         /*
 832          * This resurrects the belts and suspenders paranoia check by HPA
 833          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 834          * does not do getcwd() based path canonicalization.
 835          *
 836          * sl becomes true immediately after seeing '/' and continues to
 837          * be true as long as dots continue after that without intervening
 838          * non-dot character.
 839          */
 840         if (!p || (*p != '/' && *p != '~'))
 841                 return -1;
 842         sl = 1; ndot = 0;
 843         p++;
 844
 845         while (1) {
 846                 char ch = *p++;
 847                 if (sl) {
 848                         if (ch == '.')
 849                                 ndot++;
 850                         else if (ch == '/') {
 851                                 if (ndot < 3)
 852                                         /* reject //, /./ and /../ */
 853                                         return -1;
 854                                 ndot = 0;
 855                         }
 856                         else if (ch == 0) {
 857                                 if (0 < ndot && ndot < 3)
 858                                         /* reject /.$ and /..$ */
 859                                         return -1;
 860                                 return 0;
 861                         }
 862                         else
 863                                 sl = ndot = 0;
 864                 }
 865                 else if (ch == 0)
 866                         return 0;
 867                 else if (ch == '/') {
 868                         sl = 1;
 869                         ndot = 0;
 870                 }
 871         }
 872 }
 873
 874 static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
 875 {
 876         if (len < skip)
 877                 return 0;
 878         len -= skip;
 879         path += skip;
 880         while (len-- > 0) {
 881                 char c = *(path++);
 882                 if (c != ' ' && c != '.')
 883                         return 0;
 884         }
 885         return 1;
 886 }
 887
 888 int is_ntfs_dotgit(const char *name)
 889 {
 890         int len;
 891
 892         for (len = 0; ; len++)
 893                 if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
 894                         if (only_spaces_and_periods(name, len, 4) &&
 895                                         !strncasecmp(name, ".git", 4))
 896                                 return 1;
 897                         if (only_spaces_and_periods(name, len, 5) &&
 898                                         !strncasecmp(name, "git~1", 5))
 899                                 return 1;
 900                         if (name[len] != '\\')
 901                                 return 0;
 902                         name += len + 1;
 903                         len = -1;
 904                 }
 905 }
 906
 907 char *xdg_config_home(const char *filename)
 908 {
 909         const char *home, *config_home;
 910
 911         assert(filename);
 912         config_home = getenv("XDG_CONFIG_HOME");
 913         if (config_home && *config_home)
 914                 return mkpathdup("%s/git/%s", config_home, filename);
 915
 916         home = getenv("HOME");
 917         if (home)
 918                 return mkpathdup("%s/.config/git/%s", home, filename);
 919         return NULL;
 920 }