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 "namespace.h" 35 #include <sys/param.h> 36 #include <sys/stat.h> 37 38 #include <errno.h> 39 #include <stdlib.h> 40 #include <string.h> 41 #include <unistd.h> 42 #include <fcntl.h> 43 #include "un-namespace.h" 44 #include "libc_private.h" 45 46 extern int __realpathat(int fd, const char *path, char *buf, size_t size, 47 int flags); 48 49 /* 50 * Find the real name of path, by removing all ".", ".." and symlink 51 * components. Returns (resolved) on success, or (NULL) on failure, 52 * in which case the path which caused trouble is left in (resolved). 53 */ 54 static char * __noinline 55 realpath1(const char *path, char *resolved) 56 { 57 struct stat sb; 58 char *p, *q; 59 size_t left_len, resolved_len, next_token_len; 60 unsigned symlinks; 61 ssize_t slen; 62 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; 63 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 resolved[0] = '.'; 75 resolved[1] = '\0'; 76 return (NULL); 77 } 78 resolved_len = strlen(resolved); 79 left_len = strlcpy(left, path, sizeof(left)); 80 } 81 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 82 errno = ENAMETOOLONG; 83 return (NULL); 84 } 85 86 /* 87 * Iterate over path components in `left'. 88 */ 89 while (left_len != 0) { 90 /* 91 * Extract the next path component and adjust `left' 92 * and its length. 93 */ 94 p = strchr(left, '/'); 95 96 next_token_len = p != NULL ? (size_t)(p - left) : left_len; 97 memcpy(next_token, left, next_token_len); 98 next_token[next_token_len] = '\0'; 99 100 if (p != NULL) { 101 left_len -= next_token_len + 1; 102 memmove(left, p + 1, left_len + 1); 103 } else { 104 left[0] = '\0'; 105 left_len = 0; 106 } 107 108 if (resolved[resolved_len - 1] != '/') { 109 if (resolved_len + 1 >= PATH_MAX) { 110 errno = ENAMETOOLONG; 111 return (NULL); 112 } 113 resolved[resolved_len++] = '/'; 114 resolved[resolved_len] = '\0'; 115 } 116 if (next_token[0] == '\0') { 117 /* Handle consequential slashes. */ 118 continue; 119 } else if (strcmp(next_token, ".") == 0) { 120 continue; 121 } else if (strcmp(next_token, "..") == 0) { 122 /* 123 * Strip the last path component except when we have 124 * single "/" 125 */ 126 if (resolved_len > 1) { 127 resolved[resolved_len - 1] = '\0'; 128 q = strrchr(resolved, '/') + 1; 129 *q = '\0'; 130 resolved_len = q - resolved; 131 } 132 continue; 133 } 134 135 /* 136 * Append the next path component and lstat() it. 137 */ 138 resolved_len = strlcat(resolved, next_token, PATH_MAX); 139 if (resolved_len >= PATH_MAX) { 140 errno = ENAMETOOLONG; 141 return (NULL); 142 } 143 if (lstat(resolved, &sb) != 0) 144 return (NULL); 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)); 151 if (slen <= 0 || slen >= (ssize_t)sizeof(symlink)) { 152 if (slen < 0) 153 ; /* keep errno from readlink(2) call */ 154 else if (slen == 0) 155 errno = ENOENT; 156 else 157 errno = ENAMETOOLONG; 158 return (NULL); 159 } 160 symlink[slen] = '\0'; 161 if (symlink[0] == '/') { 162 resolved[1] = 0; 163 resolved_len = 1; 164 } else { 165 /* Strip the last path component. */ 166 q = strrchr(resolved, '/') + 1; 167 *q = '\0'; 168 resolved_len = q - resolved; 169 } 170 171 /* 172 * If there are any path components left, then 173 * append them to symlink. The result is placed 174 * in `left'. 175 */ 176 if (p != NULL) { 177 if (symlink[slen - 1] != '/') { 178 if (slen + 1 >= (ssize_t)sizeof(symlink)) { 179 errno = ENAMETOOLONG; 180 return (NULL); 181 } 182 symlink[slen] = '/'; 183 symlink[slen + 1] = 0; 184 } 185 left_len = strlcat(symlink, left, 186 sizeof(symlink)); 187 if (left_len >= sizeof(symlink)) { 188 errno = ENAMETOOLONG; 189 return (NULL); 190 } 191 } 192 left_len = strlcpy(left, symlink, sizeof(left)); 193 } else if (!S_ISDIR(sb.st_mode) && p != NULL) { 194 errno = ENOTDIR; 195 return (NULL); 196 } 197 } 198 199 /* 200 * Remove trailing slash except when the resolved pathname 201 * is a single "/". 202 */ 203 if (resolved_len > 1 && resolved[resolved_len - 1] == '/') 204 resolved[resolved_len - 1] = '\0'; 205 return (resolved); 206 } 207 208 char * 209 realpath(const char * __restrict path, char * __restrict resolved) 210 { 211 char *m, *res; 212 213 if (path == NULL) { 214 errno = EINVAL; 215 return (NULL); 216 } 217 if (path[0] == '\0') { 218 errno = ENOENT; 219 return (NULL); 220 } 221 if (resolved != NULL) { 222 m = NULL; 223 } else { 224 m = resolved = malloc(PATH_MAX); 225 if (resolved == NULL) 226 return (NULL); 227 } 228 if (__getosreldate() >= 1300080) { 229 if (__realpathat(AT_FDCWD, path, resolved, PATH_MAX, 0) == 0) 230 return (resolved); 231 } 232 res = realpath1(path, resolved); 233 if (res == NULL) 234 free(m); 235 return (res); 236 } 237