1/*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The names of the authors may not be used to endorse or promote 15 * products derived from this software without specific prior written 16 * permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31#include "namespace.h" 32#include <sys/param.h> 33#include <sys/stat.h> 34 35#include <errno.h> 36#include <stdlib.h> 37#include <string.h> 38#include <unistd.h> 39#include <fcntl.h> 40#include "un-namespace.h" 41#include "libc_private.h" 42 43extern int __realpathat(int fd, const char *path, char *buf, size_t size, 44 int flags); 45 46/* 47 * Find the real name of path, by removing all ".", ".." and symlink 48 * components. Returns (resolved) on success, or (NULL) on failure, 49 * in which case the path which caused trouble is left in (resolved). 50 */ 51static char * __noinline 52realpath1(const char *path, char *resolved) 53{ 54 struct stat sb; 55 char *p, *q; 56 size_t left_len, resolved_len, next_token_len; 57 unsigned symlinks; 58 ssize_t slen; 59 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; 60 61 symlinks = 0; 62 if (path[0] == '/') { 63 resolved[0] = '/'; 64 resolved[1] = '\0'; 65 if (path[1] == '\0') 66 return (resolved); 67 resolved_len = 1; 68 left_len = strlcpy(left, path + 1, sizeof(left)); 69 } else { 70 if (getcwd(resolved, PATH_MAX) == NULL) { 71 resolved[0] = '.'; 72 resolved[1] = '\0'; 73 return (NULL); 74 } 75 resolved_len = strlen(resolved); 76 left_len = strlcpy(left, path, sizeof(left)); 77 } 78 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 79 errno = ENAMETOOLONG; 80 return (NULL); 81 } 82 83 /* 84 * Iterate over path components in `left'. 85 */ 86 while (left_len != 0) { 87 /* 88 * Extract the next path component and adjust `left' 89 * and its length. 90 */ 91 p = strchr(left, '/'); 92 93 next_token_len = p != NULL ? (size_t)(p - left) : left_len; 94 memcpy(next_token, left, next_token_len); 95 next_token[next_token_len] = '\0'; 96 97 if (p != NULL) { 98 left_len -= next_token_len + 1; 99 memmove(left, p + 1, left_len + 1); 100 } else { 101 left[0] = '\0'; 102 left_len = 0; 103 } 104 105 if (resolved[resolved_len - 1] != '/') { 106 if (resolved_len + 1 >= PATH_MAX) { 107 errno = ENAMETOOLONG; 108 return (NULL); 109 } 110 resolved[resolved_len++] = '/'; 111 resolved[resolved_len] = '\0'; 112 } 113 if (next_token[0] == '\0') { 114 /* Handle consequential slashes. */ 115 continue; 116 } else if (strcmp(next_token, ".") == 0) { 117 continue; 118 } else if (strcmp(next_token, "..") == 0) { 119 /* 120 * Strip the last path component except when we have 121 * single "/" 122 */ 123 if (resolved_len > 1) { 124 resolved[resolved_len - 1] = '\0'; 125 q = strrchr(resolved, '/') + 1; 126 *q = '\0'; 127 resolved_len = q - resolved; 128 } 129 continue; 130 } 131 132 /* 133 * Append the next path component and lstat() it. 134 */ 135 resolved_len = strlcat(resolved, next_token, PATH_MAX); 136 if (resolved_len >= PATH_MAX) { 137 errno = ENAMETOOLONG; 138 return (NULL); 139 } 140 if (lstat(resolved, &sb) != 0) 141 return (NULL); 142 if (S_ISLNK(sb.st_mode)) { 143 if (symlinks++ > MAXSYMLINKS) { 144 errno = ELOOP; 145 return (NULL); 146 } 147 slen = readlink(resolved, symlink, sizeof(symlink)); 148 if (slen <= 0 || slen >= (ssize_t)sizeof(symlink)) { 149 if (slen < 0) 150 ; /* keep errno from readlink(2) call */ 151 else if (slen == 0) 152 errno = ENOENT; 153 else 154 errno = ENAMETOOLONG; 155 return (NULL); 156 } 157 symlink[slen] = '\0'; 158 if (symlink[0] == '/') { 159 resolved[1] = 0; 160 resolved_len = 1; 161 } else { 162 /* Strip the last path component. */ 163 q = strrchr(resolved, '/') + 1; 164 *q = '\0'; 165 resolved_len = q - resolved; 166 } 167 168 /* 169 * If there are any path components left, then 170 * append them to symlink. The result is placed 171 * in `left'. 172 */ 173 if (p != NULL) { 174 if (symlink[slen - 1] != '/') { 175 if (slen + 1 >= (ssize_t)sizeof(symlink)) { 176 errno = ENAMETOOLONG; 177 return (NULL); 178 } 179 symlink[slen] = '/'; 180 symlink[slen + 1] = 0; 181 } 182 left_len = strlcat(symlink, left, 183 sizeof(symlink)); 184 if (left_len >= sizeof(symlink)) { 185 errno = ENAMETOOLONG; 186 return (NULL); 187 } 188 } 189 left_len = strlcpy(left, symlink, sizeof(left)); 190 } else if (!S_ISDIR(sb.st_mode) && p != NULL) { 191 errno = ENOTDIR; 192 return (NULL); 193 } 194 } 195 196 /* 197 * Remove trailing slash except when the resolved pathname 198 * is a single "/". 199 */ 200 if (resolved_len > 1 && resolved[resolved_len - 1] == '/') 201 resolved[resolved_len - 1] = '\0'; 202 return (resolved); 203} 204 205char * 206realpath(const char * __restrict path, char * __restrict resolved) 207{ 208 char *m, *res; 209 210 if (path == NULL) { 211 errno = EINVAL; 212 return (NULL); 213 } 214 if (path[0] == '\0') { 215 errno = ENOENT; 216 return (NULL); 217 } 218 if (resolved != NULL) { 219 m = NULL; 220 } else { 221 m = resolved = malloc(PATH_MAX); 222 if (resolved == NULL) 223 return (NULL); 224 } 225 if (__getosreldate() >= 1300080) { 226 if (__realpathat(AT_FDCWD, path, resolved, PATH_MAX, 0) == 0) 227 return (resolved); 228 } 229 res = realpath1(path, resolved); 230 if (res == NULL) 231 free(m); 232 return (res); 233} 234