250 lines
6.4 KiB
C
250 lines
6.4 KiB
C
/*
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* Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The names of the authors may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)realpath.c 8.1 (Berkeley) 2/16/94";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "namespace.h"
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "un-namespace.h"
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/*
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* Find the real name of path, by removing all ".", ".." and symlink
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* components. Returns (resolved) on success, or (NULL) on failure,
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* in which case the path which caused trouble is left in (resolved).
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*/
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char *
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realpath(const char * __restrict path, char * __restrict resolved)
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{
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struct stat sb;
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char *p, *q, *s;
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size_t left_len, resolved_len;
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unsigned symlinks;
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int m, slen;
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char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
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if (path == NULL) {
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errno = EINVAL;
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return (NULL);
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}
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if (path[0] == '\0') {
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errno = ENOENT;
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return (NULL);
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}
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if (resolved == NULL) {
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resolved = malloc(PATH_MAX);
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if (resolved == NULL)
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return (NULL);
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m = 1;
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} else
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m = 0;
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symlinks = 0;
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if (path[0] == '/') {
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resolved[0] = '/';
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resolved[1] = '\0';
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if (path[1] == '\0')
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return (resolved);
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resolved_len = 1;
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left_len = strlcpy(left, path + 1, sizeof(left));
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} else {
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if (getcwd(resolved, PATH_MAX) == NULL) {
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if (m)
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free(resolved);
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else {
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resolved[0] = '.';
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resolved[1] = '\0';
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}
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return (NULL);
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}
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resolved_len = strlen(resolved);
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left_len = strlcpy(left, path, sizeof(left));
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}
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if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
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if (m)
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free(resolved);
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errno = ENAMETOOLONG;
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return (NULL);
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}
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/*
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* Iterate over path components in `left'.
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*/
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while (left_len != 0) {
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/*
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* Extract the next path component and adjust `left'
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* and its length.
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*/
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p = strchr(left, '/');
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s = p ? p : left + left_len;
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if (s - left >= sizeof(next_token)) {
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if (m)
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free(resolved);
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errno = ENAMETOOLONG;
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return (NULL);
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}
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memcpy(next_token, left, s - left);
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next_token[s - left] = '\0';
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left_len -= s - left;
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if (p != NULL)
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memmove(left, s + 1, left_len + 1);
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if (resolved[resolved_len - 1] != '/') {
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if (resolved_len + 1 >= PATH_MAX) {
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if (m)
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free(resolved);
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errno = ENAMETOOLONG;
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return (NULL);
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}
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resolved[resolved_len++] = '/';
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resolved[resolved_len] = '\0';
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}
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if (next_token[0] == '\0') {
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/*
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* Handle consequential slashes. The path
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* before slash shall point to a directory.
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*
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* Only the trailing slashes are not covered
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* by other checks in the loop, but we verify
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* the prefix for any (rare) "//" or "/\0"
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* occurrence to not implement lookahead.
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*/
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if (lstat(resolved, &sb) != 0) {
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if (m)
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free(resolved);
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return (NULL);
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}
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if (!S_ISDIR(sb.st_mode)) {
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if (m)
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free(resolved);
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errno = ENOTDIR;
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return (NULL);
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}
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continue;
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}
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else if (strcmp(next_token, ".") == 0)
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continue;
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else if (strcmp(next_token, "..") == 0) {
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/*
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* Strip the last path component except when we have
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* single "/"
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*/
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if (resolved_len > 1) {
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resolved[resolved_len - 1] = '\0';
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q = strrchr(resolved, '/') + 1;
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*q = '\0';
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resolved_len = q - resolved;
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}
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continue;
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}
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/*
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* Append the next path component and lstat() it.
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*/
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resolved_len = strlcat(resolved, next_token, PATH_MAX);
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if (resolved_len >= PATH_MAX) {
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if (m)
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free(resolved);
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errno = ENAMETOOLONG;
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return (NULL);
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}
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if (lstat(resolved, &sb) != 0) {
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if (m)
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free(resolved);
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return (NULL);
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}
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if (S_ISLNK(sb.st_mode)) {
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if (symlinks++ > MAXSYMLINKS) {
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if (m)
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free(resolved);
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errno = ELOOP;
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return (NULL);
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}
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slen = readlink(resolved, symlink, sizeof(symlink) - 1);
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if (slen < 0) {
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if (m)
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free(resolved);
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return (NULL);
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}
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symlink[slen] = '\0';
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if (symlink[0] == '/') {
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resolved[1] = 0;
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resolved_len = 1;
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} else if (resolved_len > 1) {
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/* Strip the last path component. */
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resolved[resolved_len - 1] = '\0';
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q = strrchr(resolved, '/') + 1;
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*q = '\0';
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resolved_len = q - resolved;
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}
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/*
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* If there are any path components left, then
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* append them to symlink. The result is placed
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* in `left'.
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*/
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if (p != NULL) {
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if (symlink[slen - 1] != '/') {
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if (slen + 1 >= sizeof(symlink)) {
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if (m)
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free(resolved);
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errno = ENAMETOOLONG;
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return (NULL);
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}
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symlink[slen] = '/';
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symlink[slen + 1] = 0;
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}
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left_len = strlcat(symlink, left,
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sizeof(symlink));
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if (left_len >= sizeof(left)) {
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if (m)
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free(resolved);
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errno = ENAMETOOLONG;
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return (NULL);
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}
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}
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left_len = strlcpy(left, symlink, sizeof(left));
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}
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}
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/*
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* Remove trailing slash except when the resolved pathname
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* is a single "/".
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*/
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if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
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resolved[resolved_len - 1] = '\0';
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return (resolved);
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}
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