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