001    /* AclEntry.java -- An entry in an ACL list.
002       Copyright (C) 1998 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    package java.security.acl;
039    
040    import java.security.Principal;
041    import java.util.Enumeration;
042    
043    /**
044     * This interface models an entry in an access control list (ACL).  Java
045     * ACL's consist of a list of entries, where each consists of a
046     * <code>Principal</code> and a list of <code>Permission</code>'s which
047     * have been granted to that <code>Principal</code>.  An ACL can also
048     * be <em>negative</em>, which indicates that the list of
049     * <code>Permission</code>'s is a list of permissions that are <em>not</em>
050     * granted to the <code>Principal</code>.  A <code>Principal</code> can
051     * have at most one regular (or positive) ACL entry and one negative
052     * ACL entry.
053     *
054     * @version 0.0
055     *
056     * @author Aaron M. Renn (arenn@urbanophile.com)
057     */
058    public interface AclEntry extends Cloneable
059    {
060     /**
061       * This method returns the <code>Principal</code> associated with this
062       * ACL entry.
063       *
064       * @return The <code>Principal</code> for this ACL entry
065       */
066      Principal getPrincipal();
067    
068      /**
069       * This method sets ths <code>Principal</code> associated with this
070       * ACL entry.  This operation will only succeed if there is not already
071       * a <code>Principal</code> assigned.
072       *
073       * @param user The <code>Principal</code> for this ACL entry
074       *
075       * @return <code>true</code> if the <code>Principal</code> was successfully set or <code>false</code> if this entry already has a <code>Principal</code>.
076       */
077      boolean setPrincipal(Principal user);
078    
079      /**
080       * This method sets this ACL entry to be a <em>negative</em> entry, indicating
081       * that it contains a list of permissions that are <em>not</em> granted
082       * to the entry's <code>Principal</code>.  Note that there is no way to
083       * undo this operation.
084       */
085      void setNegativePermissions();
086    
087      /**
088       * This method tests whether or not this ACL entry is a negative entry or not.
089       *
090       * @return <code>true</code> if this ACL entry is negative, <code>false</code> otherwise
091       */
092      boolean isNegative();
093    
094      /**
095       * This method adds the specified permission to this ACL entry.
096       *
097       * @param permission The <code>Permission</code> to add
098       *
099       * @return <code>true</code> if the permission was added or <code>false</code> if it was already set for this entry
100       */
101      boolean addPermission(Permission permission);
102    
103      /**
104       * This method deletes the specified permission to this ACL entry.
105       *
106       * @param perm The <code>Permission</code> to delete from this ACL entry.
107       *
108       * @return <code>true</code> if the permission was successfully deleted or <code>false</code> if the permission was not part of this ACL to begin with
109       */
110      boolean removePermission(Permission perm);
111    
112      /**
113       * This method tests whether or not the specified permission is associated
114       * with this ACL entry.
115       *
116       * @param permission The <code>Permission</code> to test
117       *
118       * @return <code>true</code> if this permission is associated with this entry or <code>false</code> otherwise
119       */
120      boolean checkPermission(Permission permission);
121    
122      /**
123       * This method returns a list of all <code>Permission</code> objects
124       * associated with this ACL entry as an <code>Enumeration</code>.
125       *
126       * @return A list of permissions for this ACL entry
127       */
128      Enumeration<Permission> permissions();
129    
130      /**
131       * This method returns this object as a <code>String</code>.
132       *
133       * @return A <code>String</code> representation of this object
134       */
135      String toString();
136    
137      /**
138       * This method returns a clone of this ACL entry
139       *
140       * @return A clone of this ACL entry
141       */
142      Object clone();
143    }