1 /* $Id: realpath.c,v 1.2 2010/04/21 17:47:49 sjg Exp $ */ 2 /* from: $NetBSD: getcwd.c,v 1.45 2007/10/26 19:48:14 christos Exp $ */ 3 4 /* 5 * Copyright (c) 1989, 1991, 1993, 1995 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * Jan-Simon Pendry. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 #ifdef HAVE_CONFIG_H 36 # include <config.h> 37 #endif 38 #ifndef HAVE_REALPATH 39 40 #include <sys/cdefs.h> 41 #include <sys/param.h> 42 #include <sys/stat.h> 43 44 #include <errno.h> 45 #ifdef HAVE_STDLIB_H 46 # include <stdlib.h> 47 #endif 48 #ifdef HAVE_STRING_H 49 # include <string.h> 50 #endif 51 #ifdef HAVE_UNISTD_H 52 # include <unistd.h> 53 #endif 54 55 /* 56 * char *realpath(const char *path, char resolved[MAXPATHLEN]); 57 * 58 * Find the real name of path, by removing all ".", ".." and symlink 59 * components. Returns (resolved) on success, or (NULL) on failure, 60 * in which case the path which caused trouble is left in (resolved). 61 */ 62 char * 63 realpath(const char *path, char *resolved) 64 { 65 struct stat sb; 66 int idx = 0, n, nlnk = 0; 67 const char *q; 68 char *p, wbuf[2][MAXPATHLEN]; 69 size_t len; 70 71 if (!path || !resolved || path == resolved) 72 return (NULL); 73 74 /* 75 * Build real path one by one with paying an attention to ., 76 * .. and symbolic link. 77 */ 78 79 /* 80 * `p' is where we'll put a new component with prepending 81 * a delimiter. 82 */ 83 p = resolved; 84 85 if (*path == 0) { 86 *p = 0; 87 errno = ENOENT; 88 return (NULL); 89 } 90 91 /* If relative path, start from current working directory. */ 92 if (*path != '/') { 93 /* check for resolved pointer to appease coverity */ 94 if (resolved && getcwd(resolved, MAXPATHLEN) == NULL) { 95 p[0] = '.'; 96 p[1] = 0; 97 return (NULL); 98 } 99 len = strlen(resolved); 100 if (len > 1) 101 p += len; 102 } 103 104 loop: 105 /* Skip any slash. */ 106 while (*path == '/') 107 path++; 108 109 if (*path == 0) { 110 if (p == resolved) 111 *p++ = '/'; 112 *p = 0; 113 return (resolved); 114 } 115 116 /* Find the end of this component. */ 117 q = path; 118 do 119 q++; 120 while (*q != '/' && *q != 0); 121 122 /* Test . or .. */ 123 if (path[0] == '.') { 124 if (q - path == 1) { 125 path = q; 126 goto loop; 127 } 128 if (path[1] == '.' && q - path == 2) { 129 /* Trim the last component. */ 130 if (p != resolved) 131 while (*--p != '/') 132 ; 133 path = q; 134 goto loop; 135 } 136 } 137 138 /* Append this component. */ 139 if (p - resolved + 1 + q - path + 1 > MAXPATHLEN) { 140 errno = ENAMETOOLONG; 141 if (p == resolved) 142 *p++ = '/'; 143 *p = 0; 144 return (NULL); 145 } 146 p[0] = '/'; 147 memcpy(&p[1], path, 148 /* LINTED We know q > path. */ 149 q - path); 150 p[1 + q - path] = 0; 151 152 /* 153 * If this component is a symlink, toss it and prepend link 154 * target to unresolved path. 155 */ 156 if (lstat(resolved, &sb) == -1) { 157 return (NULL); 158 } 159 if (S_ISLNK(sb.st_mode)) { 160 if (nlnk++ >= MAXSYMLINKS) { 161 errno = ELOOP; 162 return (NULL); 163 } 164 n = readlink(resolved, wbuf[idx], sizeof(wbuf[0]) - 1); 165 if (n < 0) 166 return (NULL); 167 if (n == 0) { 168 errno = ENOENT; 169 return (NULL); 170 } 171 172 /* Append unresolved path to link target and switch to it. */ 173 if (n + (len = strlen(q)) + 1 > sizeof(wbuf[0])) { 174 errno = ENAMETOOLONG; 175 return (NULL); 176 } 177 memcpy(&wbuf[idx][n], q, len + 1); 178 path = wbuf[idx]; 179 idx ^= 1; 180 181 /* If absolute symlink, start from root. */ 182 if (*path == '/') 183 p = resolved; 184 goto loop; 185 } 186 if (*q == '/' && !S_ISDIR(sb.st_mode)) { 187 errno = ENOTDIR; 188 return (NULL); 189 } 190 191 /* Advance both resolved and unresolved path. */ 192 p += 1 + q - path; 193 path = q; 194 goto loop; 195 } 196 #endif 197