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 1.2 2003/06/17 04:26:46 dillon Exp $ 31 */ 32 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 41 /* 42 * char *realpath(const char *path, char resolved[PATH_MAX]); 43 * 44 * Find the real name of path, by removing all ".", ".." and symlink 45 * components. Returns (resolved) on success, or (NULL) on failure, 46 * in which case the path which caused trouble is left in (resolved). 47 */ 48 char * 49 realpath(const char *path, char resolved[PATH_MAX]) 50 { 51 struct stat sb; 52 char *p, *q, *s; 53 size_t left_len, resolved_len; 54 unsigned symlinks; 55 int serrno, slen; 56 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; 57 58 serrno = errno; 59 symlinks = 0; 60 if (path[0] == '/') { 61 resolved[0] = '/'; 62 resolved[1] = '\0'; 63 if (path[1] == '\0') 64 return (resolved); 65 resolved_len = 1; 66 left_len = strlcpy(left, path + 1, sizeof(left)); 67 } else { 68 if (getcwd(resolved, PATH_MAX) == NULL) { 69 strlcpy(resolved, ".", PATH_MAX); 70 return (NULL); 71 } 72 resolved_len = strlen(resolved); 73 left_len = strlcpy(left, path, sizeof(left)); 74 } 75 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 76 errno = ENAMETOOLONG; 77 return (NULL); 78 } 79 80 /* 81 * Iterate over path components in `left'. 82 */ 83 while (left_len != 0) { 84 /* 85 * Extract the next path component and adjust `left' 86 * and its length. 87 */ 88 p = strchr(left, '/'); 89 s = p ? p : left + left_len; 90 if (s - left >= sizeof(next_token)) { 91 errno = ENAMETOOLONG; 92 return (NULL); 93 } 94 memcpy(next_token, left, s - left); 95 next_token[s - left] = '\0'; 96 left_len -= s - left; 97 if (p != NULL) 98 memmove(left, s + 1, left_len + 1); 99 if (resolved[resolved_len - 1] != '/') { 100 if (resolved_len + 1 >= PATH_MAX) { 101 errno = ENAMETOOLONG; 102 return (NULL); 103 } 104 resolved[resolved_len++] = '/'; 105 resolved[resolved_len] = '\0'; 106 } 107 if (next_token[0] == '\0') 108 continue; 109 else if (strcmp(next_token, ".") == 0) 110 continue; 111 else if (strcmp(next_token, "..") == 0) { 112 /* 113 * Strip the last path component except when we have 114 * single "/" 115 */ 116 if (resolved_len > 1) { 117 resolved[resolved_len - 1] = '\0'; 118 q = strrchr(resolved, '/') + 1; 119 *q = '\0'; 120 resolved_len = q - resolved; 121 } 122 continue; 123 } 124 125 /* 126 * Append the next path component and lstat() it. If 127 * lstat() fails we still can return successfully if 128 * there are no more path components left. 129 */ 130 resolved_len = strlcat(resolved, next_token, PATH_MAX); 131 if (resolved_len >= PATH_MAX) { 132 errno = ENAMETOOLONG; 133 return (NULL); 134 } 135 if (lstat(resolved, &sb) != 0) { 136 if (errno == ENOENT && p == NULL) { 137 errno = serrno; 138 return (resolved); 139 } 140 return (NULL); 141 } 142 if (S_ISLNK(sb.st_mode)) { 143 if (symlinks++ > MAXSYMLINKS) { 144 errno = ELOOP; 145 return (NULL); 146 } 147 slen = readlink(resolved, symlink, sizeof(symlink) - 1); 148 if (slen < 0) 149 return (NULL); 150 symlink[slen] = '\0'; 151 if (symlink[0] == '/') { 152 resolved[1] = 0; 153 resolved_len = 1; 154 } else if (resolved_len > 1) { 155 /* Strip the last path component. */ 156 resolved[resolved_len - 1] = '\0'; 157 q = strrchr(resolved, '/') + 1; 158 *q = '\0'; 159 resolved_len = q - resolved; 160 } 161 162 /* 163 * If there are any path components left, then 164 * append them to symlink. The result is placed 165 * in `left'. 166 */ 167 if (p != NULL) { 168 if (symlink[slen - 1] != '/') { 169 if (slen + 1 >= sizeof(symlink)) { 170 errno = ENAMETOOLONG; 171 return (NULL); 172 } 173 symlink[slen] = '/'; 174 symlink[slen + 1] = 0; 175 } 176 left_len = strlcat(symlink, left, sizeof(left)); 177 if (left_len >= sizeof(left)) { 178 errno = ENAMETOOLONG; 179 return (NULL); 180 } 181 } 182 left_len = strlcpy(left, symlink, sizeof(left)); 183 } 184 } 185 186 /* 187 * Remove trailing slash except when the resolved pathname 188 * is a single "/". 189 */ 190 if (resolved_len > 1 && resolved[resolved_len - 1] == '/') 191 resolved[resolved_len - 1] = '\0'; 192 return (resolved); 193 } 194