001    /* Acl.java -- An access control 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     * A Java access control list (ACL) is a group of individual ACL entries.
045     * These entries consist of a <code>Principal</code> and a list of
046     * permissions this <code>Principal</code> is either granted or denied.
047     * A given <code>Principal</code> can have at most one positive ACL entry
048     * (i.e., one that grants permissions) and one negative ACL entry (i.e., one
049     * that denies permissions).  If a given permission is both granted and
050     * denied, the ACL treats it as if it were never granted or denied.  If
051     * both a <code>Principal</code> and a <code>Group</code> to which the
052     * <code>Principal</code> belongs have an ACL entry, the permissions for
053     * the individual <code>Principal</code> take precedence over the
054     * permissions of the <code>Group</code> if there is a conflict.
055     * <p>
056     * Additionally, the ACL interface extends the <code>Owner</code> interface
057     * and so an ACL has owners.  Actions which modify the ACL are restricted
058     * to owners.
059     *
060     * @version 0.0
061     *
062     * @author Aaron M. Renn (arenn@urbanophile.com)
063     */
064    public interface Acl extends Owner
065    {
066    
067      /**
068       * This method returns the name of this ACL.
069       *
070       * @return The name of this ACL
071       */
072      String getName();
073    
074      /**
075       * This method sets the name of the ACL
076       *
077       * @param caller The <code>Principal</code> requesting the action.
078       * @param name The new name for this ACL.
079       *
080       * @exception NotOwnerException If the caller is not an owner of this ACL.
081       */
082      void setName(Principal caller, String name)
083        throws NotOwnerException;
084    
085      /**
086       * This method adds the specified entry to the ACL
087       *
088       * @param caller The <code>Principal</code> requesting the addition
089       * @param entry The ACL entry to add
090       *
091       * @return <code>true</code> if the entry was added, <code>false</code>
092       * if there is already an entry of the same type for the
093       * <code>Principal</code>.
094       *
095       * @exception NotOwnerException If the caller is not an owner of this ACL.
096       */
097      boolean addEntry(Principal caller, AclEntry entry)
098        throws NotOwnerException;
099    
100      /**
101       * This method delets the specified entry from the ACL
102       *
103       * @param caller The <code>Principal</code> requesting the deletion.
104       * @param entry The ACL entry to delete
105       *
106       * @return <code>true</code> if the entry was deleted, or <code>false</code>
107       * if this entry was not part of the ACL to begin with
108       *
109       * @exception NotOwnerException If the caller is not an owner of this ACL.
110       */
111      boolean removeEntry(Principal caller, AclEntry entry)
112        throws NotOwnerException;
113    
114      /**
115       * This method returns a list of all the entries in the ACL as an
116       * <code>Enumeration</code>.
117       *
118       * @return An enumeration of the ACL entries
119       */
120      Enumeration<AclEntry> entries();
121    
122      /**
123       * This method tests whether or not the specified <code>Principal</code>
124       * has the specified <code>Permission</code>
125       *
126       * @param user The <code>Principal</code> to test
127       * @param perm The <code>Permission</code> to test for
128       *
129       * @return <code>true</code> if the user has been granted the permission,
130       * <code>false</code> otherwise
131       */
132      boolean checkPermission(Principal user, Permission perm);
133    
134      /**
135       * This method returns a list of <code>Permission</code>'s that are granted
136       * to a particular <code>Principal</code>.  This includes any permissions
137       * that are granted to <code>Group</code>'s to which the <code>Principal</code>
138       * belongs unless they are overridden by a negative ACL.  This permission
139       * list is returned as an <code>Enumeration</code>.
140       *
141       * @param user The <code>Principal</code> to retrieve permissions for.
142       *
143       * @return A list of permissions for the <code>Principal</code>.
144       */
145      Enumeration<Permission> getPermissions(Principal user);
146    
147      /**
148       * This method returns the ACL as a <code>String</code>
149       *
150       * @return A <code>String</code> representation of this ACL
151       */
152      String toString();
153    }