1/*
2 *  Licensed to the Apache Software Foundation (ASF) under one or more
3 *  contributor license agreements.  See the NOTICE file distributed with
4 *  this work for additional information regarding copyright ownership.
5 *  The ASF licenses this file to You under the Apache License, Version 2.0
6 *  (the "License"); you may not use this file except in compliance with
7 *  the License.  You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 *  Unless required by applicable law or agreed to in writing, software
12 *  distributed under the License is distributed on an "AS IS" BASIS,
13 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 *  See the License for the specific language governing permissions and
15 *  limitations under the License.
16 */
17
18package java.io;
19
20import java.security.Permission;
21import java.security.PermissionCollection;
22import java.util.Enumeration;
23import java.util.Vector;
24
25/**
26 * Collects {@link FilePermission} objects and allows to query whether a
27 * particular permission is implied by it.
28 */
29final class FilePermissionCollection extends PermissionCollection implements
30        Serializable {
31
32    private static final long serialVersionUID = 2202956749081564585L;
33
34    Vector<Permission> permissions = new Vector<Permission>();
35
36    /**
37     * Construct a new FilePermissionCollection
38     */
39    public FilePermissionCollection() {
40        super();
41    }
42
43    /**
44     * Add a permission object to the permission collection.
45     *
46     * @param permission
47     *            the FilePermission object to add to the collection.
48     * @throws IllegalArgumentException
49     *             if {@code permission} is not an instance of
50     *             {@code FilePermission}.
51     * @throws IllegalStateException
52     *             if this collection is read-only.
53     * @see java.security.PermissionCollection#add(java.security.Permission)
54     */
55    @Override
56    public void add(Permission permission) {
57        if (isReadOnly()) {
58            throw new IllegalStateException();
59        }
60        if (permission instanceof FilePermission) {
61            permissions.addElement(permission);
62        } else {
63            throw new IllegalArgumentException(permission.toString());
64        }
65    }
66
67    /**
68     * Returns an enumeration for the collection of permissions.
69     *
70     * @return a permission enumeration for this permission collection.
71     * @see java.security.PermissionCollection#elements()
72     */
73    @Override
74    public Enumeration<Permission> elements() {
75        return permissions.elements();
76    }
77
78    /**
79     * Indicates whether this permissions collection implies a specific
80     * {@code permission}.
81     *
82     * @param permission
83     *            the permission to check.
84     * @see java.security.PermissionCollection#implies(java.security.Permission)
85     */
86    @Override
87    public boolean implies(Permission permission) {
88        if (permission instanceof FilePermission) {
89            FilePermission fp = (FilePermission) permission;
90            int matchedMask = 0;
91            int i = 0;
92            while (i < permissions.size()
93                    && ((matchedMask & fp.mask) != fp.mask)) {
94                // Cast will not fail since we added it
95                matchedMask |= ((FilePermission) permissions.elementAt(i))
96                        .impliesMask(permission);
97                i++;
98            }
99            return ((matchedMask & fp.mask) == fp.mask);
100        }
101        return false;
102    }
103}
104