realpath.c revision 295367
1/* $OpenBSD: realpath.c,v 1.13 2005/08/08 08:05:37 espie Exp $ */ 2/* 3 * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru> 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. The names of the authors may not be used to endorse or promote 14 * products derived from this software without specific prior written 15 * permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30/* OPENBSD ORIGINAL: lib/libc/stdlib/realpath.c */ 31 32#include "includes.h" 33 34#if !defined(HAVE_REALPATH) || defined(BROKEN_REALPATH) 35 36#include <sys/types.h> 37#include <sys/param.h> 38#include <sys/stat.h> 39 40#include <errno.h> 41#include <stdlib.h> 42#include <stddef.h> 43#include <string.h> 44#include <unistd.h> 45 46/* 47 * char *realpath(const char *path, char resolved[PATH_MAX]); 48 * 49 * Find the real name of path, by removing all ".", ".." and symlink 50 * components. Returns (resolved) on success, or (NULL) on failure, 51 * in which case the path which caused trouble is left in (resolved). 52 */ 53char * 54realpath(const char *path, char resolved[PATH_MAX]) 55{ 56 struct stat sb; 57 char *p, *q, *s; 58 size_t left_len, resolved_len; 59 unsigned symlinks; 60 int serrno, slen; 61 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; 62 63 serrno = errno; 64 symlinks = 0; 65 if (path[0] == '/') { 66 resolved[0] = '/'; 67 resolved[1] = '\0'; 68 if (path[1] == '\0') 69 return (resolved); 70 resolved_len = 1; 71 left_len = strlcpy(left, path + 1, sizeof(left)); 72 } else { 73 if (getcwd(resolved, PATH_MAX) == NULL) { 74 strlcpy(resolved, ".", PATH_MAX); 75 return (NULL); 76 } 77 resolved_len = strlen(resolved); 78 left_len = strlcpy(left, path, sizeof(left)); 79 } 80 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 81 errno = ENAMETOOLONG; 82 return (NULL); 83 } 84 85 /* 86 * Iterate over path components in `left'. 87 */ 88 while (left_len != 0) { 89 /* 90 * Extract the next path component and adjust `left' 91 * and its length. 92 */ 93 p = strchr(left, '/'); 94 s = p ? p : left + left_len; 95 if (s - left >= (ptrdiff_t)sizeof(next_token)) { 96 errno = ENAMETOOLONG; 97 return (NULL); 98 } 99 memcpy(next_token, left, s - left); 100 next_token[s - left] = '\0'; 101 left_len -= s - left; 102 if (p != NULL) 103 memmove(left, s + 1, left_len + 1); 104 if (resolved[resolved_len - 1] != '/') { 105 if (resolved_len + 1 >= PATH_MAX) { 106 errno = ENAMETOOLONG; 107 return (NULL); 108 } 109 resolved[resolved_len++] = '/'; 110 resolved[resolved_len] = '\0'; 111 } 112 if (next_token[0] == '\0') 113 continue; 114 else if (strcmp(next_token, ".") == 0) 115 continue; 116 else if (strcmp(next_token, "..") == 0) { 117 /* 118 * Strip the last path component except when we have 119 * single "/" 120 */ 121 if (resolved_len > 1) { 122 resolved[resolved_len - 1] = '\0'; 123 q = strrchr(resolved, '/') + 1; 124 *q = '\0'; 125 resolved_len = q - resolved; 126 } 127 continue; 128 } 129 130 /* 131 * Append the next path component and lstat() it. If 132 * lstat() fails we still can return successfully if 133 * there are no more path components left. 134 */ 135 resolved_len = strlcat(resolved, next_token, PATH_MAX); 136 if (resolved_len >= PATH_MAX) { 137 errno = ENAMETOOLONG; 138 return (NULL); 139 } 140 if (lstat(resolved, &sb) != 0) { 141 if (errno == ENOENT && p == NULL) { 142 errno = serrno; 143 return (resolved); 144 } 145 return (NULL); 146 } 147 if (S_ISLNK(sb.st_mode)) { 148 if (symlinks++ > MAXSYMLINKS) { 149 errno = ELOOP; 150 return (NULL); 151 } 152 slen = readlink(resolved, symlink, sizeof(symlink) - 1); 153 if (slen < 0) 154 return (NULL); 155 symlink[slen] = '\0'; 156 if (symlink[0] == '/') { 157 resolved[1] = 0; 158 resolved_len = 1; 159 } else if (resolved_len > 1) { 160 /* Strip the last path component. */ 161 resolved[resolved_len - 1] = '\0'; 162 q = strrchr(resolved, '/') + 1; 163 *q = '\0'; 164 resolved_len = q - resolved; 165 } 166 167 /* 168 * If there are any path components left, then 169 * append them to symlink. The result is placed 170 * in `left'. 171 */ 172 if (p != NULL) { 173 if (symlink[slen - 1] != '/') { 174 if (slen + 1 >= 175 (ptrdiff_t)sizeof(symlink)) { 176 errno = ENAMETOOLONG; 177 return (NULL); 178 } 179 symlink[slen] = '/'; 180 symlink[slen + 1] = 0; 181 } 182 left_len = strlcat(symlink, left, sizeof(left)); 183 if (left_len >= sizeof(left)) { 184 errno = ENAMETOOLONG; 185 return (NULL); 186 } 187 } 188 left_len = strlcpy(left, 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#endif /* !defined(HAVE_REALPATH) || defined(BROKEN_REALPATH) */ 201