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: src/lib/libc/stdlib/realpath.c,v 1.20 2003/05/28 08:23:01 fjoe Exp $ 30 * $DragonFly: src/lib/libc/stdlib/realpath.c,v 1.4 2005/04/28 13:47:15 joerg Exp $ 31 */ 32 33 #include "namespace.h" 34 #include <sys/param.h> 35 #include <sys/stat.h> 36 37 #include <errno.h> 38 #include <stdlib.h> 39 #include <string.h> 40 #include <unistd.h> 41 #include "un-namespace.h" 42 43 /* 44 * char *realpath(const char *path, char resolved[PATH_MAX]); 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 *path, char resolved[PATH_MAX]) 52 { 53 struct stat sb; 54 char *p, *q, *s; 55 size_t left_len, resolved_len; 56 unsigned symlinks; 57 int serrno, slen; 58 char left[PATH_MAX], next_token[PATH_MAX], my_symlink[PATH_MAX]; 59 60 serrno = errno; 61 symlinks = 0; 62 if (path == NULL) { 63 errno = EINVAL; 64 return (NULL); 65 } 66 if (path[0] == '/') { 67 resolved[0] = '/'; 68 resolved[1] = '\0'; 69 if (path[1] == '\0') 70 return (resolved); 71 resolved_len = 1; 72 left_len = strlcpy(left, path + 1, sizeof(left)); 73 } else { 74 if (getcwd(resolved, PATH_MAX) == NULL) { 75 strlcpy(resolved, ".", PATH_MAX); 76 return (NULL); 77 } 78 resolved_len = strlen(resolved); 79 left_len = strlcpy(left, path, sizeof(left)); 80 } 81 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 82 errno = ENAMETOOLONG; 83 return (NULL); 84 } 85 86 /* 87 * Iterate over path components in `left'. 88 */ 89 while (left_len != 0) { 90 /* 91 * Extract the next path component and adjust `left' 92 * and its length. 93 */ 94 p = strchr(left, '/'); 95 s = p ? p : left + left_len; 96 if (s >= left + sizeof(next_token)) { 97 errno = ENAMETOOLONG; 98 return (NULL); 99 } 100 memcpy(next_token, left, s - left); 101 next_token[s - left] = '\0'; 102 left_len -= s - left; 103 if (p != NULL) 104 memmove(left, s + 1, left_len + 1); 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 continue; 115 else if (strcmp(next_token, ".") == 0) 116 continue; 117 else if (strcmp(next_token, "..") == 0) { 118 /* 119 * Strip the last path component except when we have 120 * single "/" 121 */ 122 if (resolved_len > 1) { 123 resolved[resolved_len - 1] = '\0'; 124 q = strrchr(resolved, '/') + 1; 125 *q = '\0'; 126 resolved_len = q - resolved; 127 } 128 continue; 129 } 130 131 /* 132 * Append the next path component and lstat() it. If 133 * lstat() fails we still can return successfully if 134 * there are no more path components left. 135 */ 136 resolved_len = strlcat(resolved, next_token, PATH_MAX); 137 if (resolved_len >= PATH_MAX) { 138 errno = ENAMETOOLONG; 139 return (NULL); 140 } 141 if (lstat(resolved, &sb) != 0) { 142 if (errno == ENOENT && p == NULL) { 143 errno = serrno; 144 return (resolved); 145 } 146 return (NULL); 147 } 148 if (S_ISLNK(sb.st_mode)) { 149 if (symlinks++ > MAXSYMLINKS) { 150 errno = ELOOP; 151 return (NULL); 152 } 153 slen = readlink(resolved, my_symlink, sizeof(my_symlink) - 1); 154 if (slen < 0) 155 return (NULL); 156 my_symlink[slen] = '\0'; 157 if (my_symlink[0] == '/') { 158 resolved[1] = 0; 159 resolved_len = 1; 160 } else if (resolved_len > 1) { 161 /* Strip the last path component. */ 162 resolved[resolved_len - 1] = '\0'; 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 (my_symlink[slen - 1] != '/') { 175 if (slen + 1 >= (int)sizeof(my_symlink)) { 176 errno = ENAMETOOLONG; 177 return (NULL); 178 } 179 my_symlink[slen] = '/'; 180 my_symlink[slen + 1] = 0; 181 } 182 left_len = strlcat(my_symlink, left, sizeof(left)); 183 if (left_len >= sizeof(left)) { 184 errno = ENAMETOOLONG; 185 return (NULL); 186 } 187 } 188 left_len = strlcpy(left, my_symlink, sizeof(left)); 189 } 190 } 191 192 /* 193 * Remove trailing slash except when the resolved pathname 194 * is a single "/". 195 */ 196 if (resolved_len > 1 && resolved[resolved_len - 1] == '/') 197 resolved[resolved_len - 1] = '\0'; 198 return (resolved); 199 } 200