1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
23 * Use is subject to license terms.
24 */
25
26#pragma ident	"%Z%%M%	%I%	%E% SMI"
27
28/*
29 * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
30 *
31 * Redistribution and use in source and binary forms, with or without
32 * modification, are permitted provided that the following conditions
33 * are met:
34 * 1. Redistributions of source code must retain the above copyright
35 *    notice, this list of conditions and the following disclaimer.
36 * 2. Redistributions in binary form must reproduce the above copyright
37 *    notice, this list of conditions and the following disclaimer in the
38 *    documentation and/or other materials provided with the distribution.
39 * 3. The names of the authors may not be used to endorse or promote
40 *    products derived from this software without specific prior written
41 *    permission.
42 *
43 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
44 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
45 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
46 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
47 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
48 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
49 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
50 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
51 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
52 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
53 * SUCH DAMAGE.
54 */
55/*
56 * http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/stdlib/realpath.c
57 * $OpenBSD: realpath.c,v 1.13 2005/08/08 08:05:37 espie Exp $
58 */
59
60#include <stdio.h>
61#include <unistd.h>
62#include <string.h>
63#include <limits.h>
64#include <errno.h>
65#include <sys/types.h>
66#include <sys/stat.h>
67#include <sys/param.h>
68
69/*
70 * char *s_realpath(const char *path, char resolved_path[MAXPATHLEN]);
71 *
72 * Find the real name of path, by removing all ".", ".." and symlink
73 * components.  Returns (resolved) on success, or (NULL) on failure,
74 * in which case the path which caused trouble is left in (resolved).
75 *
76 * DEVINFO: For libdevinfo we have added code to special case symlinks into
77 * /devices - the path below that point is known to not point to any
78 * additional symlinks.  This knowledge allows us to avoid causing attach.
79 */
80char *
81s_realpath(const char *path, char *resolved)
82{
83	struct stat sb;
84	char *p, *q, *s;
85	size_t left_len, resolved_len;
86	unsigned symlinks;
87	int serrno, slen;
88	char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
89
90	serrno = errno;
91	symlinks = 0;
92	if (path[0] == '/') {
93		resolved[0] = '/';
94		resolved[1] = '\0';
95		if (path[1] == '\0')
96			return (resolved);
97		resolved_len = 1;
98		left_len = strlcpy(left, path + 1, sizeof (left));
99	} else {
100		if (getcwd(resolved, PATH_MAX) == NULL) {
101			(void) strlcpy(resolved, ".", PATH_MAX);
102			return (NULL);
103		}
104		resolved_len = strlen(resolved);
105		left_len = strlcpy(left, path, sizeof (left));
106	}
107	if (left_len >= sizeof (left) || resolved_len >= PATH_MAX) {
108		errno = ENAMETOOLONG;
109		return (NULL);
110	}
111
112	/*
113	 * Iterate over path components in `left'.
114	 */
115	while (left_len != 0) {
116		/*
117		 * Extract the next path component and adjust `left'
118		 * and its length.
119		 */
120		p = strchr(left, '/');
121		s = p ? p : left + left_len;
122		if (s - left >= sizeof (next_token)) {
123			errno = ENAMETOOLONG;
124			return (NULL);
125		}
126		(void) memcpy(next_token, left, s - left);
127		next_token[s - left] = '\0';
128		left_len -= s - left;
129		if (p != NULL)
130			(void) memmove(left, s + 1, left_len + 1);
131		if (resolved[resolved_len - 1] != '/') {
132			if (resolved_len + 1 >= PATH_MAX) {
133				errno = ENAMETOOLONG;
134				return (NULL);
135			}
136			resolved[resolved_len++] = '/';
137			resolved[resolved_len] = '\0';
138		}
139		if (next_token[0] == '\0')
140			continue;
141		else if (strcmp(next_token, ".") == 0)
142			continue;
143		else if (strcmp(next_token, "..") == 0) {
144			/*
145			 * Strip the last path component except when we have
146			 * single "/"
147			 */
148			if (resolved_len > 1) {
149				resolved[resolved_len - 1] = '\0';
150				q = strrchr(resolved, '/') + 1;
151				*q = '\0';
152				resolved_len = q - resolved;
153			}
154			continue;
155		}
156
157		/*
158		 * Append the next path component and lstat() it. If
159		 * lstat() fails we still can return successfully if
160		 * there are no more path components left.
161		 */
162		resolved_len = strlcat(resolved, next_token, PATH_MAX);
163		if (resolved_len >= PATH_MAX) {
164			errno = ENAMETOOLONG;
165			return (NULL);
166		}
167
168		/*
169		 * DEVINFO: Check if link points into /devices and resolve
170		 * without causing attach if that is the case - there are no
171		 * further symlinks in /devices.
172		 */
173		if (strcmp(resolved, "/devices") == 0) {
174			resolved[resolved_len] = '/';
175			resolved_len = strlcat(resolved, left, sizeof (left));
176			left_len = 0;
177			continue;
178		}
179
180		if (lstat(resolved, &sb) != 0) {
181			if (errno == ENOENT && p == NULL) {
182				errno = serrno;
183				return (resolved);
184			}
185			return (NULL);
186		}
187
188		if (S_ISLNK(sb.st_mode)) {
189			if (symlinks++ > MAXSYMLINKS) {
190				errno = ELOOP;
191				return (NULL);
192			}
193			slen = readlink(resolved, symlink,
194			    sizeof (symlink) - 1);
195			if (slen < 0)
196				return (NULL);
197			symlink[slen] = '\0';
198
199			if (symlink[0] == '/') {
200				resolved[1] = 0;
201				resolved_len = 1;
202			} else if (resolved_len > 1) {
203				/* Strip the last path component. */
204				resolved[resolved_len - 1] = '\0';
205				q = strrchr(resolved, '/') + 1;
206				*q = '\0';
207				resolved_len = q - resolved;
208			}
209
210			/*
211			 * If there are any path components left, then
212			 * append them to symlink. The result is placed
213			 * in `left'.
214			 */
215			if (p != NULL) {
216				if (symlink[slen - 1] != '/') {
217					if (slen + 1 >= sizeof (symlink)) {
218						errno = ENAMETOOLONG;
219						return (NULL);
220					}
221					symlink[slen] = '/';
222					symlink[slen + 1] = 0;
223				}
224				left_len = strlcat(symlink, left,
225				    sizeof (left));
226				if (left_len >= sizeof (left)) {
227					errno = ENAMETOOLONG;
228					return (NULL);
229				}
230			}
231			left_len = strlcpy(left, symlink, sizeof (left));
232		}
233	}
234
235	/*
236	 * Remove trailing slash except when the resolved pathname
237	 * is a single "/".
238	 */
239	if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
240		resolved[resolved_len - 1] = '\0';
241	return (resolved);
242}
243