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.security.acl;
19
20import java.security.Principal;
21import java.util.Enumeration;
22
23/**
24 * The <i>Access Control List Entry</i> interface definition.
25 * <p>
26 * An {@code AclEntry} is a list of the {@link Permission}s that are
27 *  granted (<i>positive</i>) or denied (<i>negative</i>) to a {@link Principal}.
28 */
29public interface AclEntry extends Cloneable {
30
31    /**
32     * Set the principal for this ACL entry.
33     * <p>
34     * The principal for an ACL entry can only be set once.
35     *
36     * @param user
37     *            the principal for this ACL entry.
38     * @return {@code true} on success, {@code false} if there is a principal already set for
39     *         this entry.
40     */
41    boolean setPrincipal(Principal user);
42
43    /**
44     * Returns the principal of this ACL entry.
45     *
46     * @return the principal of this ACL entry, or null if none is set.
47     */
48    Principal getPrincipal();
49
50    /**
51     * Sets this ACL entry to be <i>negative</i>.
52     * <p>
53     * The permissions in this ACL entry will be denied to the principal
54     * associated with this entry.
55     * <p>
56     * Note: An ACL entry is <i>positive</i> by default and can only become
57     * <i>negative</i> by calling this method.
58     */
59    void setNegativePermissions();
60
61    /**
62     * Returns whether this ACL entry is <i>negative</i>.
63     *
64     * @return {@code true} if this ACL entry is negative, {@code false} if it's positive.
65     */
66    boolean isNegative();
67
68    /**
69     * Adds the specified permission to this ACL entry.
70     *
71     * @param permission
72     *            the permission to be added.
73     * @return {@code true} if the specified permission is added, {@code false} if the
74     *         permission was already in this entry.
75     */
76    boolean addPermission(Permission permission);
77
78    /**
79     * Removes the specified permission from this ACL entry.
80     *
81     * @param permission
82     *            the permission to be removed.
83     * @return {@code true} if the permission is removed, {@code false} if the permission was
84     *         not in this entry.
85     */
86    boolean removePermission(Permission permission);
87
88    /**
89     * Checks whether the specified permission is in this ACL entry.
90     *
91     * @param permission
92     *            the permission to check.
93     * @return {@code true} if the permission is in this entry, otherwise {@code false}.
94     */
95    boolean checkPermission(Permission permission);
96
97    /**
98     * Returns the list of permissions of this ACL entry.
99     *
100     * @return the list of permissions of this ACL entry,
101     */
102    Enumeration<Permission> permissions();
103
104    /**
105     * Returns the string representation of this ACL entry.
106     *
107     * @return the string representation of this ACL entry.
108     */
109    String toString();
110
111    /**
112     * Clones this ACL entry instance.
113     *
114     * @return a copy of this entry.
115     */
116    Object clone();
117
118}
119