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') {
68 if (resolved == NULL) {
69 resolved = malloc(PATH_MAX);
82 left_len = strlcpy(left, path + 1, sizeof(left));
84 if (getcwd(resolved, PATH_MAX) == NULL) {
93 resolved_len = strlen(resolved);
94 left_len = strlcpy(left, path, sizeof(left));
96 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
104 * Iterate over path components in `left'.
106 while (left_len != 0) {
108 * Extract the next path component and adjust `left'
111 p = strchr(left, '/');
112 s = p ? p : left + left_len;
113 if (s - left >= sizeof(next_token)) {
116 errno = ENAMETOOLONG;
119 memcpy(next_token, left, s - left);
120 next_token[s - left] = '\0';
121 left_len -= s - left;
123 memmove(left, s + 1, left_len + 1);
124 if (resolved[resolved_len - 1] != '/') {
125 if (resolved_len + 1 >= PATH_MAX) {
128 errno = ENAMETOOLONG;
131 resolved[resolved_len++] = '/';
132 resolved[resolved_len] = '\0';
134 if (next_token[0] == '\0') {
135 /* Handle consequential slashes. */
138 else if (strcmp(next_token, ".") == 0)
140 else if (strcmp(next_token, "..") == 0) {
142 * Strip the last path component except when we have
145 if (resolved_len > 1) {
146 resolved[resolved_len - 1] = '\0';
147 q = strrchr(resolved, '/') + 1;
149 resolved_len = q - resolved;
155 * Append the next path component and lstat() it.
157 resolved_len = strlcat(resolved, next_token, PATH_MAX);
158 if (resolved_len >= PATH_MAX) {
161 errno = ENAMETOOLONG;
164 if (lstat(resolved, &sb) != 0) {
169 if (S_ISLNK(sb.st_mode)) {
170 if (symlinks++ > MAXSYMLINKS) {
176 slen = readlink(resolved, symlink, sizeof(symlink) - 1);
182 symlink[slen] = '\0';
183 if (symlink[0] == '/') {
186 } else if (resolved_len > 1) {
187 /* Strip the last path component. */
188 resolved[resolved_len - 1] = '\0';
189 q = strrchr(resolved, '/') + 1;
191 resolved_len = q - resolved;
195 * If there are any path components left, then
196 * append them to symlink. The result is placed
200 if (symlink[slen - 1] != '/') {
201 if (slen + 1 >= sizeof(symlink)) {
204 errno = ENAMETOOLONG;
208 symlink[slen + 1] = 0;
210 left_len = strlcat(symlink, left,
212 if (left_len >= sizeof(left)) {
215 errno = ENAMETOOLONG;
219 left_len = strlcpy(left, symlink, sizeof(left));
220 } else if (!S_ISDIR(sb.st_mode) && p != NULL) {
229 * Remove trailing slash except when the resolved pathname
232 if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
233 resolved[resolved_len - 1] = '\0';