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 29 #if defined(LIBC_SCCS) && !defined(lint) 30 static char sccsid[] = "@(#)realpath.c 8.1 (Berkeley) 2/16/94"; 31 #endif /* LIBC_SCCS and not lint */ 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "namespace.h" 36 #include <sys/param.h> 37 #include <sys/stat.h> 38 39 #include <errno.h> 40 #include <string.h> 41 #include <unistd.h> 42 #include "un-namespace.h" 43 44 /* 45 * char *realpath(const char *path, char resolved_path[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[PATH_MAX]) 53 { 54 unsigned num_symlinks = 0; 55 int saved_errno = errno; 56 57 char left[PATH_MAX]; 58 size_t left_len, resolved_len; 59 60 if (path[0] == '/') { 61 resolved_path[0] = '/'; 62 resolved_path[1] = '\0'; 63 if (path[1] == '\0') 64 return resolved_path; 65 resolved_len = 1; 66 left_len = strlcpy(left, path + 1, PATH_MAX); 67 } else { 68 if (getcwd(resolved_path, PATH_MAX) == NULL) { 69 strlcpy(resolved_path, ".", PATH_MAX); 70 return NULL; 71 } 72 resolved_len = strlen(resolved_path); 73 left_len = strlcpy(left, path, PATH_MAX); 74 } 75 if (left_len >= PATH_MAX || resolved_len >= PATH_MAX) { 76 errno = ENAMETOOLONG; 77 return NULL; 78 } 79 80 while (left_len > 0) { 81 struct stat st; 82 char next_token[PATH_MAX]; 83 char *p; 84 char *s = (p = strchr(left, '/')) ? p : left + left_len; 85 86 memmove(next_token, left, s - left); 87 left_len -= s - left; 88 if (p != NULL) 89 memmove(left, s + 1, left_len + 1); 90 91 next_token[s - left] = '\0'; 92 if (resolved_path[resolved_len - 1] != '/') { 93 if (resolved_len + 1 >= PATH_MAX) { 94 errno = ENAMETOOLONG; 95 return NULL; 96 } 97 98 resolved_path[resolved_len++] = '/'; 99 resolved_path[resolved_len] = '\0'; 100 } 101 102 if (next_token[0] == '\0') 103 continue; 104 else if (!strcmp(next_token, ".")) 105 continue; 106 else if (!strcmp(next_token, "..")) { 107 if (resolved_len > 1) { 108 char *q; 109 110 /* trailing slash */ 111 resolved_path[resolved_len - 1] = '\0'; 112 113 q = strrchr(resolved_path, '/'); 114 *q = '\0'; 115 resolved_len = q - resolved_path; 116 } 117 continue; 118 } 119 120 /* filename */ 121 resolved_len = strlcat(resolved_path, next_token, PATH_MAX); 122 if (resolved_len >= PATH_MAX) { 123 errno = ENAMETOOLONG; 124 return NULL; 125 } 126 127 if (lstat(resolved_path, &st) < 0) { 128 if (errno == ENOENT && p == NULL) { 129 errno = saved_errno; 130 return resolved_path; 131 } 132 133 return NULL; 134 } 135 136 if ((st.st_mode & S_IFLNK) == S_IFLNK) { 137 char symlink[PATH_MAX]; 138 int slen; 139 140 if (num_symlinks++ > MAXSYMLINKS) { 141 errno = ELOOP; 142 return NULL; 143 } 144 slen = readlink(resolved_path, symlink, PATH_MAX - 1); 145 if (slen < 0) 146 return NULL; 147 symlink[slen] = '\0'; 148 149 if (symlink[0] == '/') { 150 /* absolute link */ 151 resolved_path[1] = 0; 152 resolved_len = 1; 153 } else if (resolved_len > 1) { 154 char *q; 155 156 /* trailing slash */ 157 resolved_path[resolved_len - 1] = '\0'; 158 159 q = strrchr(resolved_path, '/'); 160 *q = '\0'; 161 resolved_len = q - resolved_path; 162 } 163 164 if (symlink[slen - 1] != '/' && p != NULL) { 165 if (slen >= PATH_MAX) { 166 errno = ENAMETOOLONG; 167 return NULL; 168 } 169 170 symlink[slen] = '/'; 171 symlink[slen + 1] = 0; 172 } 173 if (p != NULL) 174 left_len = strlcat(symlink, left, PATH_MAX); 175 if (left_len > PATH_MAX) { 176 errno = ENAMETOOLONG; 177 return NULL; 178 } 179 left_len = strlcpy(left, symlink, PATH_MAX); 180 } 181 } 182 183 if (resolved_len > 1 && resolved_path[resolved_len - 1] == '/') 184 resolved_path[resolved_len - 1] = '\0'; 185 186 return resolved_path; 187 } 188