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) 30static 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: stable/11/lib/libc/stdlib/realpath.c 319128 2017-05-29 12:55:26Z kib $"); 34 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 "un-namespace.h" 44 45/* 46 * Find the real name of path, by removing all ".", ".." and symlink 47 * components. Returns (resolved) on success, or (NULL) on failure, 48 * in which case the path which caused trouble is left in (resolved). 49 */ 50static char * 51realpath1(const char *path, char *resolved) 52{ 53 struct stat sb; 54 char *p, *q; 55 size_t left_len, resolved_len, next_token_len; 56 unsigned symlinks; 57 ssize_t slen; 58 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; 59 60 symlinks = 0; 61 if (path[0] == '/') { 62 resolved[0] = '/'; 63 resolved[1] = '\0'; 64 if (path[1] == '\0') 65 return (resolved); 66 resolved_len = 1; 67 left_len = strlcpy(left, path + 1, sizeof(left)); 68 } else { 69 if (getcwd(resolved, PATH_MAX) == NULL) { 70 resolved[0] = '.'; 71 resolved[1] = '\0'; 72 return (NULL); 73 } 74 resolved_len = strlen(resolved); 75 left_len = strlcpy(left, path, sizeof(left)); 76 } 77 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { 78 errno = ENAMETOOLONG; 79 return (NULL); 80 } 81 82 /* 83 * Iterate over path components in `left'. 84 */ 85 while (left_len != 0) { 86 /* 87 * Extract the next path component and adjust `left' 88 * and its length. 89 */ 90 p = strchr(left, '/'); 91 92 next_token_len = p != NULL ? p - left : left_len; 93 memcpy(next_token, left, next_token_len); 94 next_token[next_token_len] = '\0'; 95 96 if (p != NULL) { 97 left_len -= next_token_len + 1; 98 memmove(left, p + 1, left_len + 1); 99 } else { 100 left[0] = '\0'; 101 left_len = 0; 102 } 103 104 if (resolved[resolved_len - 1] != '/') { 105 if (resolved_len + 1 >= PATH_MAX) { 106 errno = ENAMETOOLONG; 107 return (NULL); 108 } 109 resolved[resolved_len++] = '/'; 110 resolved[resolved_len] = '\0'; 111 } 112 if (next_token[0] == '\0') { 113 /* Handle consequential slashes. */ 114 continue; 115 } else if (strcmp(next_token, ".") == 0) { 116 continue; 117 } else if (strcmp(next_token, "..") == 0) { 118 /* 119 * Strip the last path component except when we have 120 * single "/" 121 */ 122 if (resolved_len > 1) { 123 resolved[resolved_len - 1] = '\0'; 124 q = strrchr(resolved, '/') + 1; 125 *q = '\0'; 126 resolved_len = q - resolved; 127 } 128 continue; 129 } 130 131 /* 132 * Append the next path component and lstat() it. 133 */ 134 resolved_len = strlcat(resolved, next_token, PATH_MAX); 135 if (resolved_len >= PATH_MAX) { 136 errno = ENAMETOOLONG; 137 return (NULL); 138 } 139 if (lstat(resolved, &sb) != 0) 140 return (NULL); 141 if (S_ISLNK(sb.st_mode)) { 142 if (symlinks++ > MAXSYMLINKS) { 143 errno = ELOOP; 144 return (NULL); 145 } 146 slen = readlink(resolved, symlink, sizeof(symlink)); 147 if (slen <= 0 || slen >= sizeof(symlink)) { 148 if (slen < 0) 149 ; /* keep errno from readlink(2) call */ 150 else if (slen == 0) 151 errno = ENOENT; 152 else 153 errno = ENAMETOOLONG; 154 return (NULL); 155 } 156 symlink[slen] = '\0'; 157 if (symlink[0] == '/') { 158 resolved[1] = 0; 159 resolved_len = 1; 160 } else { 161 /* Strip the last path component. */ 162 q = strrchr(resolved, '/') + 1; 163 *q = '\0'; 164 resolved_len = q - resolved; 165 } 166 167 /* 168 * If there are any path components left, then 169 * append them to symlink. The result is placed 170 * in `left'. 171 */ 172 if (p != NULL) { 173 if (symlink[slen - 1] != '/') { 174 if (slen + 1 >= sizeof(symlink)) { 175 errno = ENAMETOOLONG; 176 return (NULL); 177 } 178 symlink[slen] = '/'; 179 symlink[slen + 1] = 0; 180 } 181 left_len = strlcat(symlink, left, 182 sizeof(symlink)); 183 if (left_len >= sizeof(symlink)) { 184 errno = ENAMETOOLONG; 185 return (NULL); 186 } 187 } 188 left_len = strlcpy(left, symlink, sizeof(left)); 189 } else if (!S_ISDIR(sb.st_mode) && p != NULL) { 190 errno = ENOTDIR; 191 return (NULL); 192 } 193 } 194 195 /* 196 * Remove trailing slash except when the resolved pathname 197 * is a single "/". 198 */ 199 if (resolved_len > 1 && resolved[resolved_len - 1] == '/') 200 resolved[resolved_len - 1] = '\0'; 201 return (resolved); 202} 203 204char * 205realpath(const char * __restrict path, char * __restrict resolved) 206{ 207 char *m, *res; 208 209 if (path == NULL) { 210 errno = EINVAL; 211 return (NULL); 212 } 213 if (path[0] == '\0') { 214 errno = ENOENT; 215 return (NULL); 216 } 217 if (resolved != NULL) { 218 m = NULL; 219 } else { 220 m = resolved = malloc(PATH_MAX); 221 if (resolved == NULL) 222 return (NULL); 223 } 224 res = realpath1(path, resolved); 225 if (res == NULL) 226 free(m); 227 return (res); 228} 229