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  */
80 char *
s_realpath(const char * path,char * resolved)81 s_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