Andrew's git / gitweb.git / path.c
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path.con commit prepare_revision_walk(): check for return value in all places (81c3ce3)
   1/*
   2 * Utilities for paths and pathnames
   3 */
   4#include "cache.h"
   5#include "strbuf.h"
   6#include "string-list.h"
   7
   8static 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
  17static char bad_path[] = "/bad-path/";
  18
  19static 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
  26static 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
  37char *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
  52static 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);
  67bad:
  68        strlcpy(buf, bad_path, n);
  69        return buf;
  70}
  71
  72char *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
  82char *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
  92char *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
 107char *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
 121char *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
 133void home_config_paths(char **global, char **xdg, char *file)
 134{
 135        char *xdg_home = getenv("XDG_CONFIG_HOME");
 136        char *home = getenv("HOME");
 137        char *to_free = NULL;
 138
 139        if (!home) {
 140                if (global)
 141                        *global = NULL;
 142        } else {
 143                if (!xdg_home) {
 144                        to_free = mkpathdup("%s/.config", home);
 145                        xdg_home = to_free;
 146                }
 147                if (global)
 148                        *global = mkpathdup("%s/.gitconfig", home);
 149        }
 150
 151        if (!xdg_home)
 152                *xdg = NULL;
 153        else
 154                *xdg = mkpathdup("%s/git/%s", xdg_home, file);
 155
 156        free(to_free);
 157}
 158
 159char *git_path_submodule(const char *path, const char *fmt, ...)
 160{
 161        char *pathname = get_pathname();
 162        struct strbuf buf = STRBUF_INIT;
 163        const char *git_dir;
 164        va_list args;
 165        unsigned len;
 166
 167        len = strlen(path);
 168        if (len > PATH_MAX-100)
 169                return bad_path;
 170
 171        strbuf_addstr(&buf, path);
 172        if (len && path[len-1] != '/')
 173                strbuf_addch(&buf, '/');
 174        strbuf_addstr(&buf, ".git");
 175
 176        git_dir = read_gitfile(buf.buf);
 177        if (git_dir) {
 178                strbuf_reset(&buf);
 179                strbuf_addstr(&buf, git_dir);
 180        }
 181        strbuf_addch(&buf, '/');
 182
 183        if (buf.len >= PATH_MAX)
 184                return bad_path;
 185        memcpy(pathname, buf.buf, buf.len + 1);
 186
 187        strbuf_release(&buf);
 188        len = strlen(pathname);
 189
 190        va_start(args, fmt);
 191        len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
 192        va_end(args);
 193        if (len >= PATH_MAX)
 194                return bad_path;
 195        return cleanup_path(pathname);
 196}
 197
 198int validate_headref(const char *path)
 199{
 200        struct stat st;
 201        char *buf, buffer[256];
 202        unsigned char sha1[20];
 203        int fd;
 204        ssize_t len;
 205
 206        if (lstat(path, &st) < 0)
 207                return -1;
 208
 209        /* Make sure it is a "refs/.." symlink */
 210        if (S_ISLNK(st.st_mode)) {
 211                len = readlink(path, buffer, sizeof(buffer)-1);
 212                if (len >= 5 && !memcmp("refs/", buffer, 5))
 213                        return 0;
 214                return -1;
 215        }
 216
 217        /*
 218         * Anything else, just open it and try to see if it is a symbolic ref.
 219         */
 220        fd = open(path, O_RDONLY);
 221        if (fd < 0)
 222                return -1;
 223        len = read_in_full(fd, buffer, sizeof(buffer)-1);
 224        close(fd);
 225
 226        /*
 227         * Is it a symbolic ref?
 228         */
 229        if (len < 4)
 230                return -1;
 231        if (!memcmp("ref:", buffer, 4)) {
 232                buf = buffer + 4;
 233                len -= 4;
 234                while (len && isspace(*buf))
 235                        buf++, len--;
 236                if (len >= 5 && !memcmp("refs/", buf, 5))
 237                        return 0;
 238        }
 239
 240        /*
 241         * Is this a detached HEAD?
 242         */
 243        if (!get_sha1_hex(buffer, sha1))
 244                return 0;
 245
 246        return -1;
 247}
 248
 249static struct passwd *getpw_str(const char *username, size_t len)
 250{
 251        struct passwd *pw;
 252        char *username_z = xmemdupz(username, len);
 253        pw = getpwnam(username_z);
 254        free(username_z);
 255        return pw;
 256}
 257
 258/*
 259 * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 260 * then it is a newly allocated string. Returns NULL on getpw failure or
 261 * if path is NULL.
 262 */
 263char *expand_user_path(const char *path)
 264{
 265        struct strbuf user_path = STRBUF_INIT;
 266        const char *to_copy = path;
 267
 268        if (path == NULL)
 269                goto return_null;
 270        if (path[0] == '~') {
 271                const char *first_slash = strchrnul(path, '/');
 272                const char *username = path + 1;
 273                size_t username_len = first_slash - username;
 274                if (username_len == 0) {
 275                        const char *home = getenv("HOME");
 276                        if (!home)
 277                                goto return_null;
 278                        strbuf_add(&user_path, home, strlen(home));
 279                } else {
 280                        struct passwd *pw = getpw_str(username, username_len);
 281                        if (!pw)
 282                                goto return_null;
 283                        strbuf_add(&user_path, pw->pw_dir, strlen(pw->pw_dir));
 284                }
 285                to_copy = first_slash;
 286        }
 287        strbuf_add(&user_path, to_copy, strlen(to_copy));
 288        return strbuf_detach(&user_path, NULL);
 289return_null:
 290        strbuf_release(&user_path);
 291        return NULL;
 292}
 293
 294/*
 295 * First, one directory to try is determined by the following algorithm.
 296 *
 297 * (0) If "strict" is given, the path is used as given and no DWIM is
 298 *     done. Otherwise:
 299 * (1) "~/path" to mean path under the running user's home directory;
 300 * (2) "~user/path" to mean path under named user's home directory;
 301 * (3) "relative/path" to mean cwd relative directory; or
 302 * (4) "/absolute/path" to mean absolute directory.
 303 *
 304 * Unless "strict" is given, we try access() for existence of "%s.git/.git",
 305 * "%s/.git", "%s.git", "%s" in this order.  The first one that exists is
 306 * what we try.
 307 *
 308 * Second, we try chdir() to that.  Upon failure, we return NULL.
 309 *
 310 * Then, we try if the current directory is a valid git repository.
 311 * Upon failure, we return NULL.
 312 *
 313 * If all goes well, we return the directory we used to chdir() (but
 314 * before ~user is expanded), avoiding getcwd() resolving symbolic
 315 * links.  User relative paths are also returned as they are given,
 316 * except DWIM suffixing.
 317 */
 318const char *enter_repo(const char *path, int strict)
 319{
 320        static char used_path[PATH_MAX];
 321        static char validated_path[PATH_MAX];
 322
 323        if (!path)
 324                return NULL;
 325
 326        if (!strict) {
 327                static const char *suffix[] = {
 328                        "/.git", "", ".git/.git", ".git", NULL,
 329                };
 330                const char *gitfile;
 331                int len = strlen(path);
 332                int i;
 333                while ((1 < len) && (path[len-1] == '/'))
 334                        len--;
 335
 336                if (PATH_MAX <= len)
 337                        return NULL;
 338                strncpy(used_path, path, len); used_path[len] = 0 ;
 339                strcpy(validated_path, used_path);
 340
 341                if (used_path[0] == '~') {
 342                        char *newpath = expand_user_path(used_path);
 343                        if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
 344                                free(newpath);
 345                                return NULL;
 346                        }
 347                        /*
 348                         * Copy back into the static buffer. A pity
 349                         * since newpath was not bounded, but other
 350                         * branches of the if are limited by PATH_MAX
 351                         * anyway.
 352                         */
 353                        strcpy(used_path, newpath); free(newpath);
 354                }
 355                else if (PATH_MAX - 10 < len)
 356                        return NULL;
 357                len = strlen(used_path);
 358                for (i = 0; suffix[i]; i++) {
 359                        struct stat st;
 360                        strcpy(used_path + len, suffix[i]);
 361                        if (!stat(used_path, &st) &&
 362                            (S_ISREG(st.st_mode) ||
 363                            (S_ISDIR(st.st_mode) && is_git_directory(used_path)))) {
 364                                strcat(validated_path, suffix[i]);
 365                                break;
 366                        }
 367                }
 368                if (!suffix[i])
 369                        return NULL;
 370                gitfile = read_gitfile(used_path) ;
 371                if (gitfile)
 372                        strcpy(used_path, gitfile);
 373                if (chdir(used_path))
 374                        return NULL;
 375                path = validated_path;
 376        }
 377        else if (chdir(path))
 378                return NULL;
 379
 380        if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
 381            validate_headref("HEAD") == 0) {
 382                set_git_dir(".");
 383                check_repository_format();
 384                return path;
 385        }
 386
 387        return NULL;
 388}
 389
 390static int calc_shared_perm(int mode)
 391{
 392        int tweak;
 393
 394        if (shared_repository < 0)
 395                tweak = -shared_repository;
 396        else
 397                tweak = shared_repository;
 398
 399        if (!(mode & S_IWUSR))
 400                tweak &= ~0222;
 401        if (mode & S_IXUSR)
 402                /* Copy read bits to execute bits */
 403                tweak |= (tweak & 0444) >> 2;
 404        if (shared_repository < 0)
 405                mode = (mode & ~0777) | tweak;
 406        else
 407                mode |= tweak;
 408
 409        return mode;
 410}
 411
 412
 413int adjust_shared_perm(const char *path)
 414{
 415        int old_mode, new_mode;
 416
 417        if (!shared_repository)
 418                return 0;
 419        if (get_st_mode_bits(path, &old_mode) < 0)
 420                return -1;
 421
 422        new_mode = calc_shared_perm(old_mode);
 423        if (S_ISDIR(old_mode)) {
 424                /* Copy read bits to execute bits */
 425                new_mode |= (new_mode & 0444) >> 2;
 426                new_mode |= FORCE_DIR_SET_GID;
 427        }
 428
 429        if (((old_mode ^ new_mode) & ~S_IFMT) &&
 430                        chmod(path, (new_mode & ~S_IFMT)) < 0)
 431                return -2;
 432        return 0;
 433}
 434
 435static int have_same_root(const char *path1, const char *path2)
 436{
 437        int is_abs1, is_abs2;
 438
 439        is_abs1 = is_absolute_path(path1);
 440        is_abs2 = is_absolute_path(path2);
 441        return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 442               (!is_abs1 && !is_abs2);
 443}
 444
 445/*
 446 * Give path as relative to prefix.
 447 *
 448 * The strbuf may or may not be used, so do not assume it contains the
 449 * returned path.
 450 */
 451const char *relative_path(const char *in, const char *prefix,
 452                          struct strbuf *sb)
 453{
 454        int in_len = in ? strlen(in) : 0;
 455        int prefix_len = prefix ? strlen(prefix) : 0;
 456        int in_off = 0;
 457        int prefix_off = 0;
 458        int i = 0, j = 0;
 459
 460        if (!in_len)
 461                return "./";
 462        else if (!prefix_len)
 463                return in;
 464
 465        if (have_same_root(in, prefix)) {
 466                /* bypass dos_drive, for "c:" is identical to "C:" */
 467                if (has_dos_drive_prefix(in)) {
 468                        i = 2;
 469                        j = 2;
 470                }
 471        } else {
 472                return in;
 473        }
 474
 475        while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 476                if (is_dir_sep(prefix[i])) {
 477                        while (is_dir_sep(prefix[i]))
 478                                i++;
 479                        while (is_dir_sep(in[j]))
 480                                j++;
 481                        prefix_off = i;
 482                        in_off = j;
 483                } else {
 484                        i++;
 485                        j++;
 486                }
 487        }
 488
 489        if (
 490            /* "prefix" seems like prefix of "in" */
 491            i >= prefix_len &&
 492            /*
 493             * but "/foo" is not a prefix of "/foobar"
 494             * (i.e. prefix not end with '/')
 495             */
 496            prefix_off < prefix_len) {
 497                if (j >= in_len) {
 498                        /* in="/a/b", prefix="/a/b" */
 499                        in_off = in_len;
 500                } else if (is_dir_sep(in[j])) {
 501                        /* in="/a/b/c", prefix="/a/b" */
 502                        while (is_dir_sep(in[j]))
 503                                j++;
 504                        in_off = j;
 505                } else {
 506                        /* in="/a/bbb/c", prefix="/a/b" */
 507                        i = prefix_off;
 508                }
 509        } else if (
 510                   /* "in" is short than "prefix" */
 511                   j >= in_len &&
 512                   /* "in" not end with '/' */
 513                   in_off < in_len) {
 514                if (is_dir_sep(prefix[i])) {
 515                        /* in="/a/b", prefix="/a/b/c/" */
 516                        while (is_dir_sep(prefix[i]))
 517                                i++;
 518                        in_off = in_len;
 519                }
 520        }
 521        in += in_off;
 522        in_len -= in_off;
 523
 524        if (i >= prefix_len) {
 525                if (!in_len)
 526                        return "./";
 527                else
 528                        return in;
 529        }
 530
 531        strbuf_reset(sb);
 532        strbuf_grow(sb, in_len);
 533
 534        while (i < prefix_len) {
 535                if (is_dir_sep(prefix[i])) {
 536                        strbuf_addstr(sb, "../");
 537                        while (is_dir_sep(prefix[i]))
 538                                i++;
 539                        continue;
 540                }
 541                i++;
 542        }
 543        if (!is_dir_sep(prefix[prefix_len - 1]))
 544                strbuf_addstr(sb, "../");
 545
 546        strbuf_addstr(sb, in);
 547
 548        return sb->buf;
 549}
 550
 551/*
 552 * A simpler implementation of relative_path
 553 *
 554 * Get relative path by removing "prefix" from "in". This function
 555 * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
 556 * to increase performance when traversing the path to work_tree.
 557 */
 558const char *remove_leading_path(const char *in, const char *prefix)
 559{
 560        static char buf[PATH_MAX + 1];
 561        int i = 0, j = 0;
 562
 563        if (!prefix || !prefix[0])
 564                return in;
 565        while (prefix[i]) {
 566                if (is_dir_sep(prefix[i])) {
 567                        if (!is_dir_sep(in[j]))
 568                                return in;
 569                        while (is_dir_sep(prefix[i]))
 570                                i++;
 571                        while (is_dir_sep(in[j]))
 572                                j++;
 573                        continue;
 574                } else if (in[j] != prefix[i]) {
 575                        return in;
 576                }
 577                i++;
 578                j++;
 579        }
 580        if (
 581            /* "/foo" is a prefix of "/foo" */
 582            in[j] &&
 583            /* "/foo" is not a prefix of "/foobar" */
 584            !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
 585           )
 586                return in;
 587        while (is_dir_sep(in[j]))
 588                j++;
 589        if (!in[j])
 590                strcpy(buf, ".");
 591        else
 592                strcpy(buf, in + j);
 593        return buf;
 594}
 595
 596/*
 597 * It is okay if dst == src, but they should not overlap otherwise.
 598 *
 599 * Performs the following normalizations on src, storing the result in dst:
 600 * - Ensures that components are separated by '/' (Windows only)
 601 * - Squashes sequences of '/'.
 602 * - Removes "." components.
 603 * - Removes ".." components, and the components the precede them.
 604 * Returns failure (non-zero) if a ".." component appears as first path
 605 * component anytime during the normalization. Otherwise, returns success (0).
 606 *
 607 * Note that this function is purely textual.  It does not follow symlinks,
 608 * verify the existence of the path, or make any system calls.
 609 *
 610 * prefix_len != NULL is for a specific case of prefix_pathspec():
 611 * assume that src == dst and src[0..prefix_len-1] is already
 612 * normalized, any time "../" eats up to the prefix_len part,
 613 * prefix_len is reduced. In the end prefix_len is the remaining
 614 * prefix that has not been overridden by user pathspec.
 615 */
 616int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
 617{
 618        char *dst0;
 619
 620        if (has_dos_drive_prefix(src)) {
 621                *dst++ = *src++;
 622                *dst++ = *src++;
 623        }
 624        dst0 = dst;
 625
 626        if (is_dir_sep(*src)) {
 627                *dst++ = '/';
 628                while (is_dir_sep(*src))
 629                        src++;
 630        }
 631
 632        for (;;) {
 633                char c = *src;
 634
 635                /*
 636                 * A path component that begins with . could be
 637                 * special:
 638                 * (1) "." and ends   -- ignore and terminate.
 639                 * (2) "./"           -- ignore them, eat slash and continue.
 640                 * (3) ".." and ends  -- strip one and terminate.
 641                 * (4) "../"          -- strip one, eat slash and continue.
 642                 */
 643                if (c == '.') {
 644                        if (!src[1]) {
 645                                /* (1) */
 646                                src++;
 647                        } else if (is_dir_sep(src[1])) {
 648                                /* (2) */
 649                                src += 2;
 650                                while (is_dir_sep(*src))
 651                                        src++;
 652                                continue;
 653                        } else if (src[1] == '.') {
 654                                if (!src[2]) {
 655                                        /* (3) */
 656                                        src += 2;
 657                                        goto up_one;
 658                                } else if (is_dir_sep(src[2])) {
 659                                        /* (4) */
 660                                        src += 3;
 661                                        while (is_dir_sep(*src))
 662                                                src++;
 663                                        goto up_one;
 664                                }
 665                        }
 666                }
 667
 668                /* copy up to the next '/', and eat all '/' */
 669                while ((c = *src++) != '\0' && !is_dir_sep(c))
 670                        *dst++ = c;
 671                if (is_dir_sep(c)) {
 672                        *dst++ = '/';
 673                        while (is_dir_sep(c))
 674                                c = *src++;
 675                        src--;
 676                } else if (!c)
 677                        break;
 678                continue;
 679
 680        up_one:
 681                /*
 682                 * dst0..dst is prefix portion, and dst[-1] is '/';
 683                 * go up one level.
 684                 */
 685                dst--;  /* go to trailing '/' */
 686                if (dst <= dst0)
 687                        return -1;
 688                /* Windows: dst[-1] cannot be backslash anymore */
 689                while (dst0 < dst && dst[-1] != '/')
 690                        dst--;
 691                if (prefix_len && *prefix_len > dst - dst0)
 692                        *prefix_len = dst - dst0;
 693        }
 694        *dst = '\0';
 695        return 0;
 696}
 697
 698int normalize_path_copy(char *dst, const char *src)
 699{
 700        return normalize_path_copy_len(dst, src, NULL);
 701}
 702
 703/*
 704 * path = Canonical absolute path
 705 * prefixes = string_list containing normalized, absolute paths without
 706 * trailing slashes (except for the root directory, which is denoted by "/").
 707 *
 708 * Determines, for each path in prefixes, whether the "prefix"
 709 * is an ancestor directory of path.  Returns the length of the longest
 710 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 711 * is an ancestor.  (Note that this means 0 is returned if prefixes is
 712 * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
 713 * are not considered to be their own ancestors.  path must be in a
 714 * canonical form: empty components, or "." or ".." components are not
 715 * allowed.
 716 */
 717int longest_ancestor_length(const char *path, struct string_list *prefixes)
 718{
 719        int i, max_len = -1;
 720
 721        if (!strcmp(path, "/"))
 722                return -1;
 723
 724        for (i = 0; i < prefixes->nr; i++) {
 725                const char *ceil = prefixes->items[i].string;
 726                int len = strlen(ceil);
 727
 728                if (len == 1 && ceil[0] == '/')
 729                        len = 0; /* root matches anything, with length 0 */
 730                else if (!strncmp(path, ceil, len) && path[len] == '/')
 731                        ; /* match of length len */
 732                else
 733                        continue; /* no match */
 734
 735                if (len > max_len)
 736                        max_len = len;
 737        }
 738
 739        return max_len;
 740}
 741
 742/* strip arbitrary amount of directory separators at end of path */
 743static inline int chomp_trailing_dir_sep(const char *path, int len)
 744{
 745        while (len && is_dir_sep(path[len - 1]))
 746                len--;
 747        return len;
 748}
 749
 750/*
 751 * If path ends with suffix (complete path components), returns the
 752 * part before suffix (sans trailing directory separators).
 753 * Otherwise returns NULL.
 754 */
 755char *strip_path_suffix(const char *path, const char *suffix)
 756{
 757        int path_len = strlen(path), suffix_len = strlen(suffix);
 758
 759        while (suffix_len) {
 760                if (!path_len)
 761                        return NULL;
 762
 763                if (is_dir_sep(path[path_len - 1])) {
 764                        if (!is_dir_sep(suffix[suffix_len - 1]))
 765                                return NULL;
 766                        path_len = chomp_trailing_dir_sep(path, path_len);
 767                        suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 768                }
 769                else if (path[--path_len] != suffix[--suffix_len])
 770                        return NULL;
 771        }
 772
 773        if (path_len && !is_dir_sep(path[path_len - 1]))
 774                return NULL;
 775        return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
 776}
 777
 778int daemon_avoid_alias(const char *p)
 779{
 780        int sl, ndot;
 781
 782        /*
 783         * This resurrects the belts and suspenders paranoia check by HPA
 784         * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 785         * does not do getcwd() based path canonicalization.
 786         *
 787         * sl becomes true immediately after seeing '/' and continues to
 788         * be true as long as dots continue after that without intervening
 789         * non-dot character.
 790         */
 791        if (!p || (*p != '/' && *p != '~'))
 792                return -1;
 793        sl = 1; ndot = 0;
 794        p++;
 795
 796        while (1) {
 797                char ch = *p++;
 798                if (sl) {
 799                        if (ch == '.')
 800                                ndot++;
 801                        else if (ch == '/') {
 802                                if (ndot < 3)
 803                                        /* reject //, /./ and /../ */
 804                                        return -1;
 805                                ndot = 0;
 806                        }
 807                        else if (ch == 0) {
 808                                if (0 < ndot && ndot < 3)
 809                                        /* reject /.$ and /..$ */
 810                                        return -1;
 811                                return 0;
 812                        }
 813                        else
 814                                sl = ndot = 0;
 815                }
 816                else if (ch == 0)
 817                        return 0;
 818                else if (ch == '/') {
 819                        sl = 1;
 820                        ndot = 0;
 821                }
 822        }
 823}
 824
 825int offset_1st_component(const char *path)
 826{
 827        if (has_dos_drive_prefix(path))
 828                return 2 + is_dir_sep(path[2]);
 829        return is_dir_sep(path[0]);
 830}