2 * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
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
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
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("$FreeBSD$");
35 #include "namespace.h"
36 #include <sys/param.h>
43 #include "un-namespace.h"
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).
51 realpath(const char * __restrict path, char * __restrict resolved)
55 size_t left_len, resolved_len;
58 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
64 if (path[0] == '\0') {
69 if (resolved == NULL) {
70 resolved = malloc(PATH_MAX);
83 left_len = strlcpy(left, path + 1, sizeof(left));
85 if (getcwd(resolved, PATH_MAX) == NULL) {
94 resolved_len = strlen(resolved);
95 left_len = strlcpy(left, path, sizeof(left));
97 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
100 errno = ENAMETOOLONG;
105 * Iterate over path components in `left'.
107 while (left_len != 0) {
109 * Extract the next path component and adjust `left'
112 p = strchr(left, '/');
113 s = p ? p : left + left_len;
114 if (s - left >= sizeof(next_token)) {
117 errno = ENAMETOOLONG;
120 memcpy(next_token, left, s - left);
121 next_token[s - left] = '\0';
122 left_len -= s - left;
124 memmove(left, s + 1, left_len + 1);
125 if (resolved[resolved_len - 1] != '/') {
126 if (resolved_len + 1 >= PATH_MAX) {
129 errno = ENAMETOOLONG;
132 resolved[resolved_len++] = '/';
133 resolved[resolved_len] = '\0';
135 if (next_token[0] == '\0')
137 else if (strcmp(next_token, ".") == 0)
139 else if (strcmp(next_token, "..") == 0) {
141 * Strip the last path component except when we have
144 if (resolved_len > 1) {
145 resolved[resolved_len - 1] = '\0';
146 q = strrchr(resolved, '/') + 1;
148 resolved_len = q - resolved;
154 * Append the next path component and lstat() it. If
155 * lstat() fails we still can return successfully if
156 * there are no more path components left.
158 resolved_len = strlcat(resolved, next_token, PATH_MAX);
159 if (resolved_len >= PATH_MAX) {
162 errno = ENAMETOOLONG;
165 if (lstat(resolved, &sb) != 0) {
166 if (errno == ENOENT && p == NULL) {
174 if (S_ISLNK(sb.st_mode)) {
175 if (symlinks++ > MAXSYMLINKS) {
181 slen = readlink(resolved, symlink, sizeof(symlink) - 1);
187 symlink[slen] = '\0';
188 if (symlink[0] == '/') {
191 } else if (resolved_len > 1) {
192 /* Strip the last path component. */
193 resolved[resolved_len - 1] = '\0';
194 q = strrchr(resolved, '/') + 1;
196 resolved_len = q - resolved;
200 * If there are any path components left, then
201 * append them to symlink. The result is placed
205 if (symlink[slen - 1] != '/') {
206 if (slen + 1 >= sizeof(symlink)) {
209 errno = ENAMETOOLONG;
213 symlink[slen + 1] = 0;
215 left_len = strlcat(symlink, left, sizeof(left));
216 if (left_len >= sizeof(left)) {
219 errno = ENAMETOOLONG;
223 left_len = strlcpy(left, symlink, sizeof(left));
228 * Remove trailing slash except when the resolved pathname
231 if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
232 resolved[resolved_len - 1] = '\0';