1 /* $OpenBSD: realpath.c,v 1.13 2005/08/08 08:05:37 espie Exp $ */ 2 /* 3 * Copyright (c) 2003 Constantin S. Svintsoff <kostik (at) 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/param.h> 37 #include <sys/stat.h> 38 39 #include <errno.h> 40 #include <stdlib.h> 41 #include <string.h> 42 #include <unistd.h> 43 44 /* 45 * char *realpath(const char *path, char resolved[PATH_MAX]); 46 * 47 * Find the real name of path, by removing all ".", ".." and symlink 48 * components. Returns (resolved) on success, or (NULL) on failure, 49 * in which case the path which caused trouble is left in (resolved). 50 */ 51 char * 52 realpath(const char *path, char resolved[PATH_MAX]) 53 { 54 struct stat sb; 55 char *p, *q, *s; 56 size_t left_len, resolved_len; 57 unsigned symlinks; 58 int serrno, slen; 59 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; 60 61 serrno = errno; 62 symlinks = 0; 63 if (path[0] == '/') { 64 resolved[0] = '/'; 65 resolved[1] = '\0'; 66 if (path[1] == '\0') 67 return (resolved); 68 resolved_len = 1; 69 left_len = strlcpy(left, path + 1, sizeof(left)); 70 } else { 71 if (getcwd(resolved, PATH_MAX) == NULL) { 72 strlcpy(resolved, ".", PATH_MAX); 73 return (NULL); 74 } 75 resolved_len = strlen(resolved); 76 left_len = strlcpy(left, path, sizeof(left)); 77 } 78 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 79 errno = ENAMETOOLONG; 80 return (NULL); 81 } 82 83 /* 84 * Iterate over path components in `left'. 85 */ 86 while (left_len != 0) { 87 /* 88 * Extract the next path component and adjust `left' 89 * and its length. 90 */ 91 p = strchr(left, '/'); 92 s = p ? p : left + left_len; 93 if (s - left >= sizeof(next_token)) { 94 errno = ENAMETOOLONG; 95 return (NULL); 96 } 97 memcpy(next_token, left, s - left); 98 next_token[s - left] = '\0'; 99 left_len -= s - left; 100 if (p != NULL) 101 memmove(left, s + 1, left_len + 1); 102 if (resolved[resolved_len - 1] != '/') { 103 if (resolved_len + 1 >= PATH_MAX) { 104 errno = ENAMETOOLONG; 105 return (NULL); 106 } 107 resolved[resolved_len++] = '/'; 108 resolved[resolved_len] = '\0'; 109 } 110 if (next_token[0] == '\0') 111 continue; 112 else if (strcmp(next_token, ".") == 0) 113 continue; 114 else if (strcmp(next_token, "..") == 0) { 115 /* 116 * Strip the last path component except when we have 117 * single "/" 118 */ 119 if (resolved_len > 1) { 120 resolved[resolved_len - 1] = '\0'; 121 q = strrchr(resolved, '/') + 1; 122 *q = '\0'; 123 resolved_len = q - resolved; 124 } 125 continue; 126 } 127 128 /* 129 * Append the next path component and lstat() it. If 130 * lstat() fails we still can return successfully if 131 * there are no more path components left. 132 */ 133 resolved_len = strlcat(resolved, next_token, PATH_MAX); 134 if (resolved_len >= PATH_MAX) { 135 errno = ENAMETOOLONG; 136 return (NULL); 137 } 138 if (lstat(resolved, &sb) != 0) { 139 if (errno == ENOENT && p == NULL) { 140 errno = serrno; 141 return (resolved); 142 } 143 return (NULL); 144 } 145 if (S_ISLNK(sb.st_mode)) { 146 if (symlinks++ > MAXSYMLINKS) { 147 errno = ELOOP; 148 return (NULL); 149 } 150 slen = readlink(resolved, symlink, sizeof(symlink) - 1); 151 if (slen < 0) 152 return (NULL); 153 symlink[slen] = '\0'; 154 if (symlink[0] == '/') { 155 resolved[1] = 0; 156 resolved_len = 1; 157 } else if (resolved_len > 1) { 158 /* Strip the last path component. */ 159 resolved[resolved_len - 1] = '\0'; 160 q = strrchr(resolved, '/') + 1; 161 *q = '\0'; 162 resolved_len = q - resolved; 163 } 164 165 /* 166 * If there are any path components left, then 167 * append them to symlink. The result is placed 168 * in `left'. 169 */ 170 if (p != NULL) { 171 if (symlink[slen - 1] != '/') { 172 if (slen + 1 >= sizeof(symlink)) { 173 errno = ENAMETOOLONG; 174 return (NULL); 175 } 176 symlink[slen] = '/'; 177 symlink[slen + 1] = 0; 178 } 179 left_len = strlcat(symlink, left, sizeof(left)); 180 if (left_len >= sizeof(left)) { 181 errno = ENAMETOOLONG; 182 return (NULL); 183 } 184 } 185 left_len = strlcpy(left, symlink, sizeof(left)); 186 } 187 } 188 189 /* 190 * Remove trailing slash except when the resolved pathname 191 * is a single "/". 192 */ 193 if (resolved_len > 1 && resolved[resolved_len - 1] == '/') 194 resolved[resolved_len - 1] = '\0'; 195 return (resolved); 196 } 197 #endif /* !defined(HAVE_REALPATH) || defined(BROKEN_REALPATH) */ 198
