1 /* 2 * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru> 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. The names of the authors may not be used to endorse or promote 13 * products derived from this software without specific prior written 14 * permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 * @(#)realpath.c 8.1 (Berkeley) 2/16/94 29 * $FreeBSD: head/lib/libc/stdlib/realpath.c 264417 2014-04-13 19:48:28Z jilles $ 30 */ 31 32 #include "namespace.h" 33 #include <sys/param.h> 34 #include <sys/stat.h> 35 36 #include <errno.h> 37 #include <stdlib.h> 38 #include <string.h> 39 #include <unistd.h> 40 #include "un-namespace.h" 41 42 int __realpath(const char *path, char *rbuf, size_t len); 43 44 /* 45 * Find the real name of path, by removing all ".", ".." and symlink 46 * components. Returns (resolved) on success, or (NULL) on failure, 47 * in which case the path which caused trouble is left in (resolved). 48 */ 49 char * 50 realpath(const char * __restrict path, char * __restrict resolved) 51 { 52 struct stat sb; 53 char *p, *q, *s; 54 size_t left_len, resolved_len; 55 unsigned symlinks; 56 int m, slen; 57 char left[PATH_MAX], next_token[PATH_MAX], my_symlink[PATH_MAX]; 58 59 if (path == NULL) { 60 errno = EINVAL; 61 return (NULL); 62 } 63 if (path[0] == '\0') { 64 errno = ENOENT; 65 return (NULL); 66 } 67 if (resolved == NULL) { 68 resolved = malloc(PATH_MAX); 69 if (resolved == NULL) 70 return (NULL); 71 m = 1; 72 } else { 73 m = 0; 74 } 75 76 if (getosreldate() >= 500710) { 77 if (__realpath(path, resolved, PATH_MAX) < 0) { 78 if (m) 79 free(resolved); 80 return (NULL); 81 } 82 return resolved; 83 } 84 85 symlinks = 0; 86 if (path[0] == '/') { 87 resolved[0] = '/'; 88 resolved[1] = '\0'; 89 if (path[1] == '\0') 90 return (resolved); 91 resolved_len = 1; 92 left_len = strlcpy(left, path + 1, sizeof(left)); 93 } else { 94 if (getcwd(resolved, PATH_MAX) == NULL) { 95 if (m) { 96 free(resolved); 97 } else { 98 resolved[0] = '.'; 99 resolved[1] = '\0'; 100 } 101 return (NULL); 102 } 103 resolved_len = strlen(resolved); 104 left_len = strlcpy(left, path, sizeof(left)); 105 } 106 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 107 if (m) 108 free(resolved); 109 errno = ENAMETOOLONG; 110 return (NULL); 111 } 112 113 /* 114 * Iterate over path components in `left'. 115 */ 116 while (left_len != 0) { 117 /* 118 * Extract the next path component and adjust `left' 119 * and its length. 120 */ 121 p = strchr(left, '/'); 122 s = p ? p : left + left_len; 123 if (s - left >= sizeof(next_token)) { 124 if (m) 125 free(resolved); 126 errno = ENAMETOOLONG; 127 return (NULL); 128 } 129 memcpy(next_token, left, s - left); 130 next_token[s - left] = '\0'; 131 left_len -= s - left; 132 if (p != NULL) 133 memmove(left, s + 1, left_len + 1); 134 if (resolved[resolved_len - 1] != '/') { 135 if (resolved_len + 1 >= PATH_MAX) { 136 if (m) 137 free(resolved); 138 errno = ENAMETOOLONG; 139 return (NULL); 140 } 141 resolved[resolved_len++] = '/'; 142 resolved[resolved_len] = '\0'; 143 } 144 if (next_token[0] == '\0') { 145 /* Handle consequential slashes. */ 146 continue; 147 } else if (strcmp(next_token, ".") == 0) { 148 continue; 149 } else if (strcmp(next_token, "..") == 0) { 150 /* 151 * Strip the last path component except when we have 152 * single "/" 153 */ 154 if (resolved_len > 1) { 155 resolved[resolved_len - 1] = '\0'; 156 q = strrchr(resolved, '/') + 1; 157 *q = '\0'; 158 resolved_len = q - resolved; 159 } 160 continue; 161 } 162 163 /* 164 * Append the next path component and lstat() it. 165 */ 166 resolved_len = strlcat(resolved, next_token, PATH_MAX); 167 if (resolved_len >= PATH_MAX) { 168 if (m) 169 free(resolved); 170 errno = ENAMETOOLONG; 171 return (NULL); 172 } 173 if (lstat(resolved, &sb) != 0) { 174 if (m) 175 free(resolved); 176 return (NULL); 177 } 178 if (S_ISLNK(sb.st_mode)) { 179 if (symlinks++ > MAXSYMLINKS) { 180 if (m) 181 free(resolved); 182 errno = ELOOP; 183 return (NULL); 184 } 185 slen = readlink(resolved, my_symlink, sizeof(my_symlink) - 1); 186 if (slen < 0) { 187 if (m) 188 free(resolved); 189 return (NULL); 190 } 191 my_symlink[slen] = '\0'; 192 if (my_symlink[0] == '/') { 193 resolved[1] = 0; 194 resolved_len = 1; 195 } else if (resolved_len > 1) { 196 /* Strip the last path component. */ 197 resolved[resolved_len - 1] = '\0'; 198 q = strrchr(resolved, '/') + 1; 199 *q = '\0'; 200 resolved_len = q - resolved; 201 } 202 203 /* 204 * If there are any path components left, then 205 * append them to symlink. The result is placed 206 * in `left'. 207 */ 208 if (p != NULL) { 209 if (my_symlink[slen - 1] != '/') { 210 if (slen + 1 >= (int)sizeof(my_symlink)) { 211 if (m) 212 free(resolved); 213 errno = ENAMETOOLONG; 214 return (NULL); 215 } 216 my_symlink[slen] = '/'; 217 my_symlink[slen + 1] = 0; 218 } 219 left_len = strlcat(my_symlink, left, 220 sizeof(my_symlink)); 221 if (left_len >= sizeof(left)) { 222 if (m) 223 free(resolved); 224 errno = ENAMETOOLONG; 225 return (NULL); 226 } 227 } 228 left_len = strlcpy(left, my_symlink, sizeof(left)); 229 } else if (!S_ISDIR(sb.st_mode) && p != NULL) { 230 if (m) 231 free(resolved); 232 errno = ENOTDIR; 233 return (NULL); 234 } 235 } 236 237 /* 238 * Remove trailing slash except when the resolved pathname 239 * is a single "/". 240 */ 241 if (resolved_len > 1 && resolved[resolved_len - 1] == '/') 242 resolved[resolved_len - 1] = '\0'; 243 return (resolved); 244 } 245