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 #include "namespace.h" 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 #include <fcntl.h> 44 #include "un-namespace.h" 45 #include "libc_private.h" 46 47 extern int __realpathat(int fd, const char *path, char *buf, size_t size, 48 int flags); 49 50 /* 51 * Find the real name of path, by removing all ".", ".." and symlink 52 * components. Returns (resolved) on success, or (NULL) on failure, 53 * in which case the path which caused trouble is left in (resolved). 54 */ 55 static char * __noinline 56 realpath1(const char *path, char *resolved) 57 { 58 struct stat sb; 59 char *p, *q; 60 size_t left_len, resolved_len, next_token_len; 61 unsigned symlinks; 62 ssize_t slen; 63 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; 64 65 symlinks = 0; 66 if (path[0] == '/') { 67 resolved[0] = '/'; 68 resolved[1] = '\0'; 69 if (path[1] == '\0') 70 return (resolved); 71 resolved_len = 1; 72 left_len = strlcpy(left, path + 1, sizeof(left)); 73 } else { 74 if (getcwd(resolved, PATH_MAX) == NULL) { 75 resolved[0] = '.'; 76 resolved[1] = '\0'; 77 return (NULL); 78 } 79 resolved_len = strlen(resolved); 80 left_len = strlcpy(left, path, sizeof(left)); 81 } 82 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 83 errno = ENAMETOOLONG; 84 return (NULL); 85 } 86 87 /* 88 * Iterate over path components in `left'. 89 */ 90 while (left_len != 0) { 91 /* 92 * Extract the next path component and adjust `left' 93 * and its length. 94 */ 95 p = strchr(left, '/'); 96 97 next_token_len = p != NULL ? (size_t)(p - left) : left_len; 98 memcpy(next_token, left, next_token_len); 99 next_token[next_token_len] = '\0'; 100 101 if (p != NULL) { 102 left_len -= next_token_len + 1; 103 memmove(left, p + 1, left_len + 1); 104 } else { 105 left[0] = '\0'; 106 left_len = 0; 107 } 108 109 if (resolved[resolved_len - 1] != '/') { 110 if (resolved_len + 1 >= PATH_MAX) { 111 errno = ENAMETOOLONG; 112 return (NULL); 113 } 114 resolved[resolved_len++] = '/'; 115 resolved[resolved_len] = '\0'; 116 } 117 if (next_token[0] == '\0') { 118 /* Handle consequential slashes. */ 119 continue; 120 } else if (strcmp(next_token, ".") == 0) { 121 continue; 122 } else if (strcmp(next_token, "..") == 0) { 123 /* 124 * Strip the last path component except when we have 125 * single "/" 126 */ 127 if (resolved_len > 1) { 128 resolved[resolved_len - 1] = '\0'; 129 q = strrchr(resolved, '/') + 1; 130 *q = '\0'; 131 resolved_len = q - resolved; 132 } 133 continue; 134 } 135 136 /* 137 * Append the next path component and lstat() it. 138 */ 139 resolved_len = strlcat(resolved, next_token, PATH_MAX); 140 if (resolved_len >= PATH_MAX) { 141 errno = ENAMETOOLONG; 142 return (NULL); 143 } 144 if (lstat(resolved, &sb) != 0) 145 return (NULL); 146 if (S_ISLNK(sb.st_mode)) { 147 if (symlinks++ > MAXSYMLINKS) { 148 errno = ELOOP; 149 return (NULL); 150 } 151 slen = readlink(resolved, symlink, sizeof(symlink)); 152 if (slen <= 0 || slen >= (ssize_t)sizeof(symlink)) { 153 if (slen < 0) 154 ; /* keep errno from readlink(2) call */ 155 else if (slen == 0) 156 errno = ENOENT; 157 else 158 errno = ENAMETOOLONG; 159 return (NULL); 160 } 161 symlink[slen] = '\0'; 162 if (symlink[0] == '/') { 163 resolved[1] = 0; 164 resolved_len = 1; 165 } else { 166 /* Strip the last path component. */ 167 q = strrchr(resolved, '/') + 1; 168 *q = '\0'; 169 resolved_len = q - resolved; 170 } 171 172 /* 173 * If there are any path components left, then 174 * append them to symlink. The result is placed 175 * in `left'. 176 */ 177 if (p != NULL) { 178 if (symlink[slen - 1] != '/') { 179 if (slen + 1 >= (ssize_t)sizeof(symlink)) { 180 errno = ENAMETOOLONG; 181 return (NULL); 182 } 183 symlink[slen] = '/'; 184 symlink[slen + 1] = 0; 185 } 186 left_len = strlcat(symlink, left, 187 sizeof(symlink)); 188 if (left_len >= sizeof(symlink)) { 189 errno = ENAMETOOLONG; 190 return (NULL); 191 } 192 } 193 left_len = strlcpy(left, symlink, sizeof(left)); 194 } else if (!S_ISDIR(sb.st_mode) && p != NULL) { 195 errno = ENOTDIR; 196 return (NULL); 197 } 198 } 199 200 /* 201 * Remove trailing slash except when the resolved pathname 202 * is a single "/". 203 */ 204 if (resolved_len > 1 && resolved[resolved_len - 1] == '/') 205 resolved[resolved_len - 1] = '\0'; 206 return (resolved); 207 } 208 209 char * 210 realpath(const char * __restrict path, char * __restrict resolved) 211 { 212 char *m, *res; 213 214 if (path == NULL) { 215 errno = EINVAL; 216 return (NULL); 217 } 218 if (path[0] == '\0') { 219 errno = ENOENT; 220 return (NULL); 221 } 222 if (resolved != NULL) { 223 m = NULL; 224 } else { 225 m = resolved = malloc(PATH_MAX); 226 if (resolved == NULL) 227 return (NULL); 228 } 229 if (__getosreldate() >= 1300080) { 230 if (__realpathat(AT_FDCWD, path, resolved, PATH_MAX, 0) == 0) 231 return (resolved); 232 } 233 res = realpath1(path, resolved); 234 if (res == NULL) 235 free(m); 236 return (res); 237 } 238