1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The names of the authors may not be used to endorse or promote 15 * products derived from this software without specific prior written 16 * permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #if defined(LIBC_SCCS) && !defined(lint) 32 static char sccsid[] = "@(#)realpath.c 8.1 (Berkeley) 2/16/94"; 33 #endif /* LIBC_SCCS and not lint */ 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include "namespace.h" 38 #include <sys/param.h> 39 #include <sys/stat.h> 40 41 #include <errno.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include <unistd.h> 45 #include <fcntl.h> 46 #include "un-namespace.h" 47 #include "libc_private.h" 48 49 extern int __realpathat(int fd, const char *path, char *buf, size_t size, 50 int flags); 51 52 /* 53 * Find the real name of path, by removing all ".", ".." and symlink 54 * components. Returns (resolved) on success, or (NULL) on failure, 55 * in which case the path which caused trouble is left in (resolved). 56 */ 57 static char * __noinline 58 realpath1(const char *path, char *resolved) 59 { 60 struct stat sb; 61 char *p, *q; 62 size_t left_len, resolved_len, next_token_len; 63 unsigned symlinks; 64 ssize_t slen; 65 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; 66 67 symlinks = 0; 68 if (path[0] == '/') { 69 resolved[0] = '/'; 70 resolved[1] = '\0'; 71 if (path[1] == '\0') 72 return (resolved); 73 resolved_len = 1; 74 left_len = strlcpy(left, path + 1, sizeof(left)); 75 } else { 76 if (getcwd(resolved, PATH_MAX) == NULL) { 77 resolved[0] = '.'; 78 resolved[1] = '\0'; 79 return (NULL); 80 } 81 resolved_len = strlen(resolved); 82 left_len = strlcpy(left, path, sizeof(left)); 83 } 84 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 85 errno = ENAMETOOLONG; 86 return (NULL); 87 } 88 89 /* 90 * Iterate over path components in `left'. 91 */ 92 while (left_len != 0) { 93 /* 94 * Extract the next path component and adjust `left' 95 * and its length. 96 */ 97 p = strchr(left, '/'); 98 99 next_token_len = p != NULL ? (size_t)(p - left) : left_len; 100 memcpy(next_token, left, next_token_len); 101 next_token[next_token_len] = '\0'; 102 103 if (p != NULL) { 104 left_len -= next_token_len + 1; 105 memmove(left, p + 1, left_len + 1); 106 } else { 107 left[0] = '\0'; 108 left_len = 0; 109 } 110 111 if (resolved[resolved_len - 1] != '/') { 112 if (resolved_len + 1 >= PATH_MAX) { 113 errno = ENAMETOOLONG; 114 return (NULL); 115 } 116 resolved[resolved_len++] = '/'; 117 resolved[resolved_len] = '\0'; 118 } 119 if (next_token[0] == '\0') { 120 /* Handle consequential slashes. */ 121 continue; 122 } else if (strcmp(next_token, ".") == 0) { 123 continue; 124 } else if (strcmp(next_token, "..") == 0) { 125 /* 126 * Strip the last path component except when we have 127 * single "/" 128 */ 129 if (resolved_len > 1) { 130 resolved[resolved_len - 1] = '\0'; 131 q = strrchr(resolved, '/') + 1; 132 *q = '\0'; 133 resolved_len = q - resolved; 134 } 135 continue; 136 } 137 138 /* 139 * Append the next path component and lstat() it. 140 */ 141 resolved_len = strlcat(resolved, next_token, PATH_MAX); 142 if (resolved_len >= PATH_MAX) { 143 errno = ENAMETOOLONG; 144 return (NULL); 145 } 146 if (lstat(resolved, &sb) != 0) 147 return (NULL); 148 if (S_ISLNK(sb.st_mode)) { 149 if (symlinks++ > MAXSYMLINKS) { 150 errno = ELOOP; 151 return (NULL); 152 } 153 slen = readlink(resolved, symlink, sizeof(symlink)); 154 if (slen <= 0 || slen >= (ssize_t)sizeof(symlink)) { 155 if (slen < 0) 156 ; /* keep errno from readlink(2) call */ 157 else if (slen == 0) 158 errno = ENOENT; 159 else 160 errno = ENAMETOOLONG; 161 return (NULL); 162 } 163 symlink[slen] = '\0'; 164 if (symlink[0] == '/') { 165 resolved[1] = 0; 166 resolved_len = 1; 167 } else { 168 /* Strip the last path component. */ 169 q = strrchr(resolved, '/') + 1; 170 *q = '\0'; 171 resolved_len = q - resolved; 172 } 173 174 /* 175 * If there are any path components left, then 176 * append them to symlink. The result is placed 177 * in `left'. 178 */ 179 if (p != NULL) { 180 if (symlink[slen - 1] != '/') { 181 if (slen + 1 >= (ssize_t)sizeof(symlink)) { 182 errno = ENAMETOOLONG; 183 return (NULL); 184 } 185 symlink[slen] = '/'; 186 symlink[slen + 1] = 0; 187 } 188 left_len = strlcat(symlink, left, 189 sizeof(symlink)); 190 if (left_len >= sizeof(symlink)) { 191 errno = ENAMETOOLONG; 192 return (NULL); 193 } 194 } 195 left_len = strlcpy(left, symlink, sizeof(left)); 196 } else if (!S_ISDIR(sb.st_mode) && p != NULL) { 197 errno = ENOTDIR; 198 return (NULL); 199 } 200 } 201 202 /* 203 * Remove trailing slash except when the resolved pathname 204 * is a single "/". 205 */ 206 if (resolved_len > 1 && resolved[resolved_len - 1] == '/') 207 resolved[resolved_len - 1] = '\0'; 208 return (resolved); 209 } 210 211 char * 212 realpath(const char * __restrict path, char * __restrict resolved) 213 { 214 char *m, *res; 215 216 if (path == NULL) { 217 errno = EINVAL; 218 return (NULL); 219 } 220 if (path[0] == '\0') { 221 errno = ENOENT; 222 return (NULL); 223 } 224 if (resolved != NULL) { 225 m = NULL; 226 } else { 227 m = resolved = malloc(PATH_MAX); 228 if (resolved == NULL) 229 return (NULL); 230 } 231 if (__getosreldate() >= 1300080) { 232 if (__realpathat(AT_FDCWD, path, resolved, PATH_MAX, 0) == 0) 233 return (resolved); 234 } 235 res = realpath1(path, resolved); 236 if (res == NULL) 237 free(m); 238 return (res); 239 } 240