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 <stdio.h> 38 #include <stdlib.h> 39 #include <string.h> 40 #include <unistd.h> 41 #include "un-namespace.h" 42 43 int __realpath(const char *path, char *rbuf, size_t len); 44 45 /* 46 * Find the real name of path, by removing all ".", ".." and symlink 47 * components. Returns (resolved) on success, or (NULL) on failure, 48 * in which case the path which caused trouble is left in (resolved). 49 */ 50 char * 51 realpath(const char * __restrict path, char * __restrict resolved) 52 { 53 struct stat sb; 54 char *p, *q, *s; 55 size_t left_len, resolved_len; 56 unsigned symlinks; 57 int m, slen; 58 char left[PATH_MAX], next_token[PATH_MAX], my_symlink[PATH_MAX]; 59 60 if (path == NULL) { 61 errno = EINVAL; 62 return (NULL); 63 } 64 if (path[0] == '\0') { 65 errno = ENOENT; 66 return (NULL); 67 } 68 if (resolved == NULL) { 69 resolved = malloc(PATH_MAX); 70 if (resolved == NULL) 71 return (NULL); 72 m = 1; 73 } else { 74 m = 0; 75 } 76 77 if (getosreldate() >= 500710) { 78 if (__realpath(path, resolved, PATH_MAX) < 0) { 79 if (m) { 80 free(resolved); 81 } else { 82 snprintf(resolved, PATH_MAX, "%s", path); 83 } 84 return (NULL); 85 } 86 return resolved; 87 } 88 89 symlinks = 0; 90 if (path[0] == '/') { 91 resolved[0] = '/'; 92 resolved[1] = '\0'; 93 if (path[1] == '\0') 94 return (resolved); 95 resolved_len = 1; 96 left_len = strlcpy(left, path + 1, sizeof(left)); 97 } else { 98 if (getcwd(resolved, PATH_MAX) == NULL) { 99 if (m) { 100 free(resolved); 101 } else { 102 resolved[0] = '.'; 103 resolved[1] = '\0'; 104 } 105 return (NULL); 106 } 107 resolved_len = strlen(resolved); 108 left_len = strlcpy(left, path, sizeof(left)); 109 } 110 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 111 if (m) 112 free(resolved); 113 errno = ENAMETOOLONG; 114 return (NULL); 115 } 116 117 /* 118 * Iterate over path components in `left'. 119 */ 120 while (left_len != 0) { 121 /* 122 * Extract the next path component and adjust `left' 123 * and its length. 124 */ 125 p = strchr(left, '/'); 126 s = p ? p : left + left_len; 127 if (s - left >= sizeof(next_token)) { 128 if (m) 129 free(resolved); 130 errno = ENAMETOOLONG; 131 return (NULL); 132 } 133 memcpy(next_token, left, s - left); 134 next_token[s - left] = '\0'; 135 left_len -= s - left; 136 if (p != NULL) 137 memmove(left, s + 1, left_len + 1); 138 if (resolved[resolved_len - 1] != '/') { 139 if (resolved_len + 1 >= PATH_MAX) { 140 if (m) 141 free(resolved); 142 errno = ENAMETOOLONG; 143 return (NULL); 144 } 145 resolved[resolved_len++] = '/'; 146 resolved[resolved_len] = '\0'; 147 } 148 if (next_token[0] == '\0') { 149 /* Handle consequential slashes. */ 150 continue; 151 } else if (strcmp(next_token, ".") == 0) { 152 continue; 153 } else if (strcmp(next_token, "..") == 0) { 154 /* 155 * Strip the last path component except when we have 156 * single "/" 157 */ 158 if (resolved_len > 1) { 159 resolved[resolved_len - 1] = '\0'; 160 q = strrchr(resolved, '/') + 1; 161 *q = '\0'; 162 resolved_len = q - resolved; 163 } 164 continue; 165 } 166 167 /* 168 * Append the next path component and lstat() it. 169 */ 170 resolved_len = strlcat(resolved, next_token, PATH_MAX); 171 if (resolved_len >= PATH_MAX) { 172 if (m) 173 free(resolved); 174 errno = ENAMETOOLONG; 175 return (NULL); 176 } 177 if (lstat(resolved, &sb) != 0) { 178 if (m) 179 free(resolved); 180 return (NULL); 181 } 182 if (S_ISLNK(sb.st_mode)) { 183 if (symlinks++ > MAXSYMLINKS) { 184 if (m) 185 free(resolved); 186 errno = ELOOP; 187 return (NULL); 188 } 189 slen = readlink(resolved, my_symlink, sizeof(my_symlink) - 1); 190 if (slen < 0) { 191 if (m) 192 free(resolved); 193 return (NULL); 194 } 195 my_symlink[slen] = '\0'; 196 if (my_symlink[0] == '/') { 197 resolved[1] = 0; 198 resolved_len = 1; 199 } else if (resolved_len > 1) { 200 /* Strip the last path component. */ 201 resolved[resolved_len - 1] = '\0'; 202 q = strrchr(resolved, '/') + 1; 203 *q = '\0'; 204 resolved_len = q - resolved; 205 } 206 207 /* 208 * If there are any path components left, then 209 * append them to symlink. The result is placed 210 * in `left'. 211 */ 212 if (p != NULL) { 213 if (my_symlink[slen - 1] != '/') { 214 if (slen + 1 >= (int)sizeof(my_symlink)) { 215 if (m) 216 free(resolved); 217 errno = ENAMETOOLONG; 218 return (NULL); 219 } 220 my_symlink[slen] = '/'; 221 my_symlink[slen + 1] = 0; 222 } 223 left_len = strlcat(my_symlink, left, 224 sizeof(my_symlink)); 225 if (left_len >= sizeof(left)) { 226 if (m) 227 free(resolved); 228 errno = ENAMETOOLONG; 229 return (NULL); 230 } 231 } 232 left_len = strlcpy(left, my_symlink, sizeof(left)); 233 } else if (!S_ISDIR(sb.st_mode) && p != NULL) { 234 if (m) 235 free(resolved); 236 errno = ENOTDIR; 237 return (NULL); 238 } 239 } 240 241 /* 242 * Remove trailing slash except when the resolved pathname 243 * is a single "/". 244 */ 245 if (resolved_len > 1 && resolved[resolved_len - 1] == '/') 246 resolved[resolved_len - 1] = '\0'; 247 return (resolved); 248 } 249