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, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
28 /*	  All Rights Reserved  	*/
29 
30 /*
31  * University Copyright- Copyright (c) 1982, 1986, 1988
32  * The Regents of the University of California
33  * All Rights Reserved
34  *
35  * University Acknowledgment- Portions of this document are derived from
36  * software developed by the University of California, Berkeley, and its
37  * contributors.
38  */
39 
40 #pragma ident	"%Z%%M%	%I%	%E% SMI"
41 
42 /*
43  * Subdirectory detection: needed by exportfs and rpc.mountd.
44  * The above programs call issubdir() frequently, so we make
45  * it fast by caching the results of stat().
46  */
47 #include <sys/types.h>
48 #include <sys/param.h>
49 #include <sys/stat.h>
50 #include <string.h>
51 
52 #define	MAXSTATS MAXPATHLEN/2	/* maximum number of stat()'s to save */
53 
54 #define	inoeq(ino1, ino2)	((ino1) == (ino2))
55 #define	deveq(dev1, dev2)	((dev1) == (dev2))
56 
57 /*
58  * dir1 is a subdirectory of dir2 within the same filesystem if
59  *     (a) dir1 is identical to dir2
60  *     (b) dir1's parent is dir2
61  */
62 int
issubdir(dir1,dir2)63 issubdir(dir1, dir2)
64 	char *dir1;
65 	char *dir2;
66 {
67 	struct stat st;
68 	struct stat parent_st;
69 	char *p;
70 	int index;
71 
72 	static dev_t child_dev;
73 	static dev_t child_rdev;
74 	static ino_t child_ino[MAXSTATS];
75 	static int valid;
76 	static char childdir[MAXPATHLEN];
77 	static char child_fstype[_ST_FSTYPSZ];
78 
79 	/*
80 	 * Get parent directory info
81 	 */
82 	if (stat(dir2, &parent_st) < 0) {
83 		return (0);
84 	}
85 
86 	if (strcmp(childdir, dir1) != 0) {
87 		/*
88 		 * Not in cache: get child directory info
89 		 */
90 		p = strcpy(childdir, dir1) + strlen(dir1);
91 		index = 0;
92 		valid = 0;
93 		for (;;) {
94 			if (stat(childdir, &st) < 0) {
95 				childdir[0] = 0;	/* invalidate cache */
96 				return (0);
97 			}
98 			if (index == 0) {
99 				child_dev = st.st_dev;
100 				child_rdev = st.st_rdev;
101 				(void) strncpy(child_fstype, st.st_fstype,
102 						sizeof (child_fstype));
103 			}
104 			if (index > 0 &&
105 			    (child_dev != st.st_dev ||
106 				inoeq(child_ino[index - 1], st.st_ino))) {
107 				/*
108 				 * Hit root: done
109 				 */
110 				break;
111 			}
112 			child_ino[index++] = st.st_ino;
113 			if (S_ISDIR(st.st_mode)) {
114 				p = strcpy(p, "/..") + 3;
115 			} else {
116 				p = strrchr(childdir, '/');
117 				if (p == NULL) {
118 					p = strcpy(childdir, ".") + 1;
119 				} else {
120 					while (((p - 1) > childdir) &&
121 						*(p - 1) == '/') {
122 						p--;
123 					}
124 					*p = '\0';
125 				}
126 			}
127 		}
128 		valid = index;
129 		(void) strcpy(childdir, dir1);
130 	}
131 
132 	/*
133 	 * Perform the test
134 	 */
135 	if (!deveq(parent_st.st_dev, child_dev)) {
136 		return (0);
137 	}
138 
139 	/*
140 	 * Check rdev also in case of lofs
141 	 */
142 	if (((strcmp(parent_st.st_fstype, "lofs") == 0)) &&
143 		(strcmp(child_fstype, "lofs") == 0)) {
144 		if (!deveq(parent_st.st_rdev, child_rdev)) {
145 			return (0);
146 		}
147 	}
148 
149 	for (index = 0; index < valid; index++) {
150 		if (inoeq(child_ino[index], parent_st.st_ino)) {
151 			return (1);
152 		}
153 	}
154 	return (0);
155 }
156