001 /*
002 * Copyright 1999-2006 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package java.security;
027
028 /**
029 * A <code>DomainCombiner</code> provides a means to dynamically
030 * update the ProtectionDomains associated with the current
031 * <code>AccessControlContext</code>.
032 *
033 * <p> A <code>DomainCombiner</code> is passed as a parameter to the
034 * appropriate constructor for <code>AccessControlContext</code>.
035 * The newly constructed context is then passed to the
036 * <code>AccessController.doPrivileged(..., context)</code> method
037 * to bind the provided context (and associated <code>DomainCombiner</code>)
038 * with the current execution Thread. Subsequent calls to
039 * <code>AccessController.getContext</code> or
040 * <code>AccessController.checkPermission</code>
041 * cause the <code>DomainCombiner.combine</code> to get invoked.
042 *
043 * <p> The combine method takes two arguments. The first argument represents
044 * an array of ProtectionDomains from the current execution Thread,
045 * since the most recent call to <code>AccessController.doPrivileged</code>.
046 * If no call to doPrivileged was made, then the first argument will contain
047 * all the ProtectionDomains from the current execution Thread.
048 * The second argument represents an array of inherited ProtectionDomains,
049 * which may be <code>null</code>. ProtectionDomains may be inherited
050 * from a parent Thread, or from a privileged context. If no call to
051 * doPrivileged was made, then the second argument will contain the
052 * ProtectionDomains inherited from the parent Thread. If one or more calls
053 * to doPrivileged were made, and the most recent call was to
054 * doPrivileged(action, context), then the second argument will contain the
055 * ProtectionDomains from the privileged context. If the most recent call
056 * was to doPrivileged(action), then there is no privileged context,
057 * and the second argument will be <code>null</code>.
058 *
059 * <p> The <code>combine</code> method investigates the two input arrays
060 * of ProtectionDomains and returns a single array containing the updated
061 * ProtectionDomains. In the simplest case, the <code>combine</code>
062 * method merges the two stacks into one. In more complex cases,
063 * the <code>combine</code> method returns a modified
064 * stack of ProtectionDomains. The modification may have added new
065 * ProtectionDomains, removed certain ProtectionDomains, or simply
066 * updated existing ProtectionDomains. Re-ordering and other optimizations
067 * to the ProtectionDomains are also permitted. Typically the
068 * <code>combine</code> method bases its updates on the information
069 * encapsulated in the <code>DomainCombiner</code>.
070 *
071 * <p> After the <code>AccessController.getContext</code> method
072 * receives the combined stack of ProtectionDomains back from
073 * the <code>DomainCombiner</code>, it returns a new
074 * AccessControlContext that has both the combined ProtectionDomains
075 * as well as the <code>DomainCombiner</code>.
076 *
077 * @see AccessController
078 * @see AccessControlContext
079 * @version 1.16, 06/12/07
080 * @since 1.3
081 */
082 public interface DomainCombiner {
083
084 /**
085 * Modify or update the provided ProtectionDomains.
086 * ProtectionDomains may be added to or removed from the given
087 * ProtectionDomains. The ProtectionDomains may be re-ordered.
088 * Individual ProtectionDomains may be modified (with a new
089 * set of Permissions, for example).
090 *
091 * <p>
092 *
093 * @param currentDomains the ProtectionDomains associated with the
094 * current execution Thread, up to the most recent
095 * privileged <code>ProtectionDomain</code>.
096 * The ProtectionDomains are are listed in order of execution,
097 * with the most recently executing <code>ProtectionDomain</code>
098 * residing at the beginning of the array. This parameter may
099 * be <code>null</code> if the current execution Thread
100 * has no associated ProtectionDomains.<p>
101 *
102 * @param assignedDomains an array of inherited ProtectionDomains.
103 * ProtectionDomains may be inherited from a parent Thread,
104 * or from a privileged <code>AccessControlContext</code>.
105 * This parameter may be <code>null</code>
106 * if there are no inherited ProtectionDomains.
107 *
108 * @return a new array consisting of the updated ProtectionDomains,
109 * or <code>null</code>.
110 */
111 ProtectionDomain[] combine(ProtectionDomain[] currentDomains,
112 ProtectionDomain[] assignedDomains);
113 }
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