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 1.9.2.2 2003/06/02 13:31:16 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[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 strlcpy(resolved, ".", PATH_MAX); 72 return (NULL); 73 } 74 resolved_len = strlen(resolved); 75 left_len = strlcpy(left, path, sizeof(left)); 76 } 77 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 78 errno = ENAMETOOLONG; 79 return (NULL); 80 } 81 82 /* 83 * Iterate over path components in `left'. 84 */ 85 while (left_len != 0) { 86 /* 87 * Extract the next path component and adjust `left' 88 * and its length. 89 */ 90 p = strchr(left, '/'); 91 s = p ? p : left + left_len; 92 if (s >= left + sizeof(next_token)) { 93 errno = ENAMETOOLONG; 94 return (NULL); 95 } 96 memcpy(next_token, left, s - left); 97 next_token[s - left] = '\0'; 98 left_len -= s - left; 99 if (p != NULL) 100 memmove(left, s + 1, left_len + 1); 101 if (resolved[resolved_len - 1] != '/') { 102 if (resolved_len + 1 >= PATH_MAX) { 103 errno = ENAMETOOLONG; 104 return (NULL); 105 } 106 resolved[resolved_len++] = '/'; 107 resolved[resolved_len] = '\0'; 108 } 109 if (next_token[0] == '\0') 110 continue; 111 else if (strcmp(next_token, ".") == 0) 112 continue; 113 else if (strcmp(next_token, "..") == 0) { 114 /* 115 * Strip the last path component except when we have 116 * single "/" 117 */ 118 if (resolved_len > 1) { 119 resolved[resolved_len - 1] = '\0'; 120 q = strrchr(resolved, '/') + 1; 121 *q = '\0'; 122 resolved_len = q - resolved; 123 } 124 continue; 125 } 126 127 /* 128 * Append the next path component and lstat() it. If 129 * lstat() fails we still can return successfully if 130 * there are no more path components left. 131 */ 132 resolved_len = strlcat(resolved, next_token, PATH_MAX); 133 if (resolved_len >= PATH_MAX) { 134 errno = ENAMETOOLONG; 135 return (NULL); 136 } 137 if (lstat(resolved, &sb) != 0) { 138 if (errno == ENOENT && p == NULL) { 139 errno = serrno; 140 return (resolved); 141 } 142 return (NULL); 143 } 144 if (S_ISLNK(sb.st_mode)) { 145 if (symlinks++ > MAXSYMLINKS) { 146 errno = ELOOP; 147 return (NULL); 148 } 149 slen = readlink(resolved, my_symlink, sizeof(my_symlink) - 1); 150 if (slen < 0) 151 return (NULL); 152 my_symlink[slen] = '\0'; 153 if (my_symlink[0] == '/') { 154 resolved[1] = 0; 155 resolved_len = 1; 156 } else if (resolved_len > 1) { 157 /* Strip the last path component. */ 158 resolved[resolved_len - 1] = '\0'; 159 q = strrchr(resolved, '/') + 1; 160 *q = '\0'; 161 resolved_len = q - resolved; 162 } 163 164 /* 165 * If there are any path components left, then 166 * append them to symlink. The result is placed 167 * in `left'. 168 */ 169 if (p != NULL) { 170 if (my_symlink[slen - 1] != '/') { 171 if (slen + 1 >= (int)sizeof(my_symlink)) { 172 errno = ENAMETOOLONG; 173 return (NULL); 174 } 175 my_symlink[slen] = '/'; 176 my_symlink[slen + 1] = 0; 177 } 178 left_len = strlcat(my_symlink, left, sizeof(left)); 179 if (left_len >= sizeof(left)) { 180 errno = ENAMETOOLONG; 181 return (NULL); 182 } 183 } 184 left_len = strlcpy(left, my_symlink, sizeof(left)); 185 } 186 } 187 188 /* 189 * Remove trailing slash except when the resolved pathname 190 * is a single "/". 191 */ 192 if (resolved_len > 1 && resolved[resolved_len - 1] == '/') 193 resolved[resolved_len - 1] = '\0'; 194 return (resolved); 195 } 196