AclEntry


1   /*
2    * @(#)AclEntry.java    1.20 04/05/05
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   package java.security.acl;
9   
10  import java.util.Enumeration  ;
11  import java.security.Principal  ;
12  
13  /**
14   * This is the interface used for representing one entry in an Access
15   * Control List (ACL).<p>
16   *
17   * An ACL can be thought of as a data structure with multiple ACL entry
18   * objects. Each ACL entry object contains a set of permissions associated
19   * with a particular principal. (A principal represents an entity such as
20   * an individual user or a group). Additionally, each ACL entry is specified
21   * as being either positive or negative. If positive, the permissions are
22   * to be granted to the associated principal. If negative, the permissions
23   * are to be denied. Each principal can have at most one positive ACL entry
24   * and one negative entry; that is, multiple positive or negative ACL
25   * entries are not allowed for any principal.
26   *
27   * Note: ACL entries are by default positive. An entry becomes a
28   * negative entry only if the
29   * {@link #setNegativePermissions() setNegativePermissions}
30   * method is called on it.
31   *
32   * @see java.security.acl.Acl
33   *
34   * @author  Satish Dharmaraj
35   */
36  public interface AclEntry extends Cloneable   {
37  
38      /**
39       * Specifies the principal for which permissions are granted or denied
40       * by this ACL entry. If a principal was already set for this ACL entry,
41       * false is returned, otherwise true is returned.
42       *
43       * @param user the principal to be set for this entry.
44       *
45       * @return true if the principal is set, false if there was
46       * already a principal set for this entry.
47       *
48       * @see #getPrincipal
49       */
50      public boolean setPrincipal(Principal   user);
51  
52      /**
53       * Returns the principal for which permissions are granted or denied by
54       * this ACL entry. Returns null if there is no principal set for this
55       * entry yet.
56       *
57       * @return the principal associated with this entry.
58       *
59       * @see #setPrincipal
60       */
61      public Principal   getPrincipal();
62  
63      /**
64       * Sets this ACL entry to be a negative one. That is, the associated
65       * principal (e.g., a user or a group) will be denied the permission set
66       * specified in the entry.
67       *
68       * Note: ACL entries are by default positive. An entry becomes a
69       * negative entry only if this <code>setNegativePermissions</code>
70       * method is called on it.
71       */
72      public void setNegativePermissions();
73  
74      /**
75       * Returns true if this is a negative ACL entry (one denying the
76       * associated principal the set of permissions in the entry), false
77       * otherwise.
78       *
79       * @return true if this is a negative ACL entry, false if it's not.
80       */
81      public boolean isNegative();
82  
83      /**
84       * Adds the specified permission to this ACL entry. Note: An entry can
85       * have multiple permissions.
86       *
87       * @param permission the permission to be associated with
88       * the principal in this entry.
89       *
90       * @return true if the permission was added, false if the
91       * permission was already part of this entry's permission set.
92       */
93      public boolean addPermission(Permission   permission);
94  
95      /**
96       * Removes the specified permission from this ACL entry.
97       *
98       * @param permission the permission to be removed from this entry.
99       *
100      * @return true if the permission is removed, false if the
101      * permission was not part of this entry's permission set.
102      */
103     public boolean removePermission(Permission   permission);
104 
105     /**
106      * Checks if the specified permission is part of the
107      * permission set in this entry.
108      *
109      * @param permission the permission to be checked for.
110      *
111      * @return true if the permission is part of the
112      * permission set in this entry, false otherwise.
113      */
114     public boolean checkPermission(Permission   permission);
115 
116     /**
117      * Returns an enumeration of the permissions in this ACL entry.
118      *
119      * @return an enumeration of the permissions in this ACL entry.
120      */
121     public Enumeration  <Permission  > permissions();
122 
123     /**
124      * Returns a string representation of the contents of this ACL entry.
125      *
126      * @return a string representation of the contents.
127      */
128     public String   toString();
129 
130     /**
131      * Clones this ACL entry.
132      *
133      * @return a clone of this ACL entry.
134      */
135     public Object   clone();
136 }
137 
138 
139
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