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 29 #if defined(LIBC_SCCS) && !defined(lint) 30 static char sccsid[] = "@(#)realpath.c 8.1 (Berkeley) 2/16/94"; 31 #endif /* LIBC_SCCS and not lint */ 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "namespace.h" 36 #include <sys/param.h> 37 #include <sys/stat.h> 38 39 #include <errno.h> 40 #include <stdlib.h> 41 #include <string.h> 42 #include <unistd.h> 43 #include "un-namespace.h" 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 serrno, slen, m; 58 char left[PATH_MAX], next_token[PATH_MAX], 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 serrno = errno; 69 if (resolved == NULL) { 70 resolved = malloc(PATH_MAX); 71 if (resolved == NULL) 72 return (NULL); 73 m = 1; 74 } else 75 m = 0; 76 77 symlinks = 0; 78 if (path[0] == '/') { 79 resolved[0] = '/'; 80 resolved[1] = '\0'; 81 if (path[1] == '\0') 82 return (resolved); 83 resolved_len = 1; 84 left_len = strlcpy(left, path + 1, sizeof(left)); 85 } else { 86 if (getcwd(resolved, PATH_MAX) == NULL) { 87 if (m) 88 free(resolved); 89 else 90 strlcpy(resolved, ".", PATH_MAX); 91 return (NULL); 92 } 93 resolved_len = strlen(resolved); 94 left_len = strlcpy(left, path, sizeof(left)); 95 } 96 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 97 if (m) 98 free(resolved); 99 errno = ENAMETOOLONG; 100 return (NULL); 101 } 102 103 /* 104 * Iterate over path components in `left'. 105 */ 106 while (left_len != 0) { 107 /* 108 * Extract the next path component and adjust `left' 109 * and its length. 110 */ 111 p = strchr(left, '/'); 112 s = p ? p : left + left_len; 113 if (s - left >= sizeof(next_token)) { 114 if (m) 115 free(resolved); 116 errno = ENAMETOOLONG; 117 return (NULL); 118 } 119 memcpy(next_token, left, s - left); 120 next_token[s - left] = '\0'; 121 left_len -= s - left; 122 if (p != NULL) 123 memmove(left, s + 1, left_len + 1); 124 if (resolved[resolved_len - 1] != '/') { 125 if (resolved_len + 1 >= PATH_MAX) { 126 if (m) 127 free(resolved); 128 errno = ENAMETOOLONG; 129 return (NULL); 130 } 131 resolved[resolved_len++] = '/'; 132 resolved[resolved_len] = '\0'; 133 } 134 if (next_token[0] == '\0') 135 continue; 136 else if (strcmp(next_token, ".") == 0) 137 continue; 138 else if (strcmp(next_token, "..") == 0) { 139 /* 140 * Strip the last path component except when we have 141 * single "/" 142 */ 143 if (resolved_len > 1) { 144 resolved[resolved_len - 1] = '\0'; 145 q = strrchr(resolved, '/') + 1; 146 *q = '\0'; 147 resolved_len = q - resolved; 148 } 149 continue; 150 } 151 152 /* 153 * Append the next path component and lstat() it. If 154 * lstat() fails we still can return successfully if 155 * there are no more path components left. 156 */ 157 resolved_len = strlcat(resolved, next_token, PATH_MAX); 158 if (resolved_len >= PATH_MAX) { 159 if (m) 160 free(resolved); 161 errno = ENAMETOOLONG; 162 return (NULL); 163 } 164 if (lstat(resolved, &sb) != 0) { 165 if (errno == ENOENT && p == NULL) { 166 errno = serrno; 167 return (resolved); 168 } 169 if (m) 170 free(resolved); 171 return (NULL); 172 } 173 if (S_ISLNK(sb.st_mode)) { 174 if (symlinks++ > MAXSYMLINKS) { 175 if (m) 176 free(resolved); 177 errno = ELOOP; 178 return (NULL); 179 } 180 slen = readlink(resolved, symlink, sizeof(symlink) - 1); 181 if (slen < 0) { 182 if (m) 183 free(resolved); 184 return (NULL); 185 } 186 symlink[slen] = '\0'; 187 if (symlink[0] == '/') { 188 resolved[1] = 0; 189 resolved_len = 1; 190 } else if (resolved_len > 1) { 191 /* Strip the last path component. */ 192 resolved[resolved_len - 1] = '\0'; 193 q = strrchr(resolved, '/') + 1; 194 *q = '\0'; 195 resolved_len = q - resolved; 196 } 197 198 /* 199 * If there are any path components left, then 200 * append them to symlink. The result is placed 201 * in `left'. 202 */ 203 if (p != NULL) { 204 if (symlink[slen - 1] != '/') { 205 if (slen + 1 >= sizeof(symlink)) { 206 if (m) 207 free(resolved); 208 errno = ENAMETOOLONG; 209 return (NULL); 210 } 211 symlink[slen] = '/'; 212 symlink[slen + 1] = 0; 213 } 214 left_len = strlcat(symlink, left, sizeof(left)); 215 if (left_len >= sizeof(left)) { 216 if (m) 217 free(resolved); 218 errno = ENAMETOOLONG; 219 return (NULL); 220 } 221 } 222 left_len = strlcpy(left, symlink, sizeof(left)); 223 } 224 } 225 226 /* 227 * Remove trailing slash except when the resolved pathname 228 * is a single "/". 229 */ 230 if (resolved_len > 1 && resolved[resolved_len - 1] == '/') 231 resolved[resolved_len - 1] = '\0'; 232 return (resolved); 233 } 234