1 /* $OpenBSD: sftp-realpath.c,v 1.2 2021/09/02 21:03:54 deraadt Exp $ */
3 * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The names of the authors may not be used to endorse or promote
14 * products derived from this software without specific prior written
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 #include <sys/types.h>
43 # define SYMLOOP_MAX 32
46 /* XXX rewrite sftp-server to use POSIX realpath and remove this hack */
48 char *sftp_realpath(const char *path, char *resolved);
51 * char *realpath(const char *path, char resolved[PATH_MAX]);
53 * Find the real name of path, by removing all ".", ".." and symlink
54 * components. Returns (resolved) on success, or (NULL) on failure,
55 * in which case the path which caused trouble is left in (resolved).
58 sftp_realpath(const char *path, char *resolved)
62 size_t left_len, resolved_len;
64 int serrno, slen, mem_allocated;
65 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
67 if (path[0] == '\0') {
74 if (resolved == NULL) {
75 resolved = malloc(PATH_MAX);
89 left_len = strlcpy(left, path + 1, sizeof(left));
91 if (getcwd(resolved, PATH_MAX) == NULL) {
95 strlcpy(resolved, ".", PATH_MAX);
98 resolved_len = strlen(resolved);
99 left_len = strlcpy(left, path, sizeof(left));
101 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
102 errno = ENAMETOOLONG;
107 * Iterate over path components in `left'.
109 while (left_len != 0) {
111 * Extract the next path component and adjust `left'
114 p = strchr(left, '/');
115 s = p ? p : left + left_len;
116 if (s - left >= (ptrdiff_t)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) {
127 errno = ENAMETOOLONG;
130 resolved[resolved_len++] = '/';
131 resolved[resolved_len] = '\0';
133 if (next_token[0] == '\0')
135 else if (strcmp(next_token, ".") == 0)
137 else if (strcmp(next_token, "..") == 0) {
139 * Strip the last path component except when we have
142 if (resolved_len > 1) {
143 resolved[resolved_len - 1] = '\0';
144 q = strrchr(resolved, '/') + 1;
146 resolved_len = q - resolved;
152 * Append the next path component and lstat() it. If
153 * lstat() fails we still can return successfully if
154 * there are no more path components left.
156 resolved_len = strlcat(resolved, next_token, PATH_MAX);
157 if (resolved_len >= PATH_MAX) {
158 errno = ENAMETOOLONG;
161 if (lstat(resolved, &sb) != 0) {
162 if (errno == ENOENT && p == NULL) {
168 if (S_ISLNK(sb.st_mode)) {
169 if (symlinks++ > SYMLOOP_MAX) {
173 slen = readlink(resolved, symlink, sizeof(symlink) - 1);
176 symlink[slen] = '\0';
177 if (symlink[0] == '/') {
180 } else if (resolved_len > 1) {
181 /* Strip the last path component. */
182 resolved[resolved_len - 1] = '\0';
183 q = strrchr(resolved, '/') + 1;
185 resolved_len = q - resolved;
189 * If there are any path components left, then
190 * append them to symlink. The result is placed
194 if (symlink[slen - 1] != '/') {
196 (ptrdiff_t)sizeof(symlink)) {
197 errno = ENAMETOOLONG;
201 symlink[slen + 1] = 0;
203 left_len = strlcat(symlink, left, sizeof(symlink));
204 if (left_len >= sizeof(symlink)) {
205 errno = ENAMETOOLONG;
209 left_len = strlcpy(left, symlink, sizeof(left));
214 * Remove trailing slash except when the resolved pathname
217 if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
218 resolved[resolved_len - 1] = '\0';