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/*
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* Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*/
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package java.security;
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import java.util.ArrayList;
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import java.util.List;
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import sun.security.util.Debug;
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import sun.security.util.SecurityConstants;
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/**
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* An AccessControlContext is used to make system resource access decisions
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* based on the context it encapsulates.
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*
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* <p>More specifically, it encapsulates a context and
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* has a single method, <code>checkPermission</code>,
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* that is equivalent to the <code>checkPermission</code> method
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* in the AccessController class, with one difference: The AccessControlContext
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* <code>checkPermission</code> method makes access decisions based on the
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* context it encapsulates,
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* rather than that of the current execution thread.
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*
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* <p>Thus, the purpose of AccessControlContext is for those situations where
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* a security check that should be made within a given context
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* actually needs to be done from within a
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* <i>different</i> context (for example, from within a worker thread).
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*
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* <p> An AccessControlContext is created by calling the
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* <code>AccessController.getContext</code> method.
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* The <code>getContext</code> method takes a "snapshot"
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* of the current calling context, and places
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* it in an AccessControlContext object, which it returns. A sample call is
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* the following:
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*
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* <pre>
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* AccessControlContext acc = AccessController.getContext()
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* </pre>
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*
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* <p>
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* Code within a different context can subsequently call the
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* <code>checkPermission</code> method on the
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* previously-saved AccessControlContext object. A sample call is the
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* following:
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*
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* <pre>
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* acc.checkPermission(permission)
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* </pre>
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*
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* @see AccessController
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*
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* @author Roland Schemers
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*/
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public final class AccessControlContext {
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private ProtectionDomain context[];
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private boolean isPrivileged;
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// Note: This field is directly used by the virtual machine
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// native codes. Don't touch it.
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private AccessControlContext privilegedContext;
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private DomainCombiner combiner = null;
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private static boolean debugInit = false;
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private static Debug debug = null;
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static Debug getDebug()
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{
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if (debugInit)
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return debug;
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else {
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if (Policy.isSet()) {
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debug = Debug.getInstance("access");
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debugInit = true;
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}
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return debug;
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}
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}
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/**
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* Create an AccessControlContext with the given set of ProtectionDomains.
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* Context must not be null. Duplicate domains will be removed from the
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* context.
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*
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* @param context the ProtectionDomains associated with this context.
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* The non-duplicate domains are copied from the array. Subsequent
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* changes to the array will not affect this AccessControlContext.
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*/
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public AccessControlContext(ProtectionDomain context[])
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{
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if (context.length == 0) {
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this.context = null;
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} else if (context.length == 1) {
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if (context[0] != null) {
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this.context = context.clone();
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} else {
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this.context = null;
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}
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} else {
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List<ProtectionDomain> v = new ArrayList<ProtectionDomain>(context.length);
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for (int i =0; i< context.length; i++) {
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if ((context[i] != null) && (!v.contains(context[i])))
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v.add(context[i]);
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}
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this.context = new ProtectionDomain[v.size()];
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this.context = v.toArray(this.context);
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}
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}
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/**
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* Create a new <code>AccessControlContext</code> with the given
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* <code>AccessControlContext</code> and <code>DomainCombiner</code>.
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* This constructor associates the provided
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* <code>DomainCombiner</code> with the provided
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* <code>AccessControlContext</code>.
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*
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* <p>
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*
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* @param acc the <code>AccessControlContext</code> associated
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* with the provided <code>DomainCombiner</code>.
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*
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* @param combiner the <code>DomainCombiner</code> to be associated
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* with the provided <code>AccessControlContext</code>.
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*
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* @exception NullPointerException if the provided
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* <code>context</code> is <code>null</code>.
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*
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* @exception SecurityException if a security manager is installed and the
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* caller does not have the "createAccessControlContext"
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* {@link SecurityPermission}
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* @since 1.3
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*/
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public AccessControlContext(AccessControlContext acc,
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DomainCombiner combiner) {
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SecurityManager sm = System.getSecurityManager();
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if (sm != null) {
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sm.checkPermission(SecurityConstants.CREATE_ACC_PERMISSION);
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}
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this.context = acc.context;
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// we do not need to run the combine method on the
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// provided ACC. it was already "combined" when the
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// context was originally retrieved.
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//
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// at this point in time, we simply throw away the old
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// combiner and use the newly provided one.
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this.combiner = combiner;
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}
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/**
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* package private for AccessController
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*/
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AccessControlContext(ProtectionDomain context[], DomainCombiner combiner) {
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if (context != null) {
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this.context = context.clone();
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}
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this.combiner = combiner;
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}
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/**
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* package private constructor for AccessController.getContext()
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*/
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AccessControlContext(ProtectionDomain context[],
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boolean isPrivileged)
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{
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this.context = context;
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this.isPrivileged = isPrivileged;
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}
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/**
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* Returns true if this context is privileged.
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*/
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boolean isPrivileged()
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{
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return isPrivileged;
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}
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/**
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* get the assigned combiner from the privileged or inherited context
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*/
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DomainCombiner getAssignedCombiner() {
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AccessControlContext acc;
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if (isPrivileged) {
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acc = privilegedContext;
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} else {
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acc = AccessController.getInheritedAccessControlContext();
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}
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if (acc != null) {
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return acc.combiner;
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}
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return null;
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}
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/**
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* Get the <code>DomainCombiner</code> associated with this
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* <code>AccessControlContext</code>.
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*
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* <p>
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*
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* @return the <code>DomainCombiner</code> associated with this
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* <code>AccessControlContext</code>, or <code>null</code>
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* if there is none.
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*
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* @exception SecurityException if a security manager is installed and
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* the caller does not have the "getDomainCombiner"
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* {@link SecurityPermission}
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* @since 1.3
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*/
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public DomainCombiner getDomainCombiner() {
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SecurityManager sm = System.getSecurityManager();
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if (sm != null) {
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sm.checkPermission(SecurityConstants.GET_COMBINER_PERMISSION);
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}
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return combiner;
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}
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/**
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* Determines whether the access request indicated by the
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* specified permission should be allowed or denied, based on
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* the security policy currently in effect, and the context in
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* this object. The request is allowed only if every ProtectionDomain
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* in the context implies the permission. Otherwise the request is
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* denied.
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*
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* <p>
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* This method quietly returns if the access request
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* is permitted, or throws a suitable AccessControlException otherwise.
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*
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* @param perm the requested permission.
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*
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* @exception AccessControlException if the specified permission
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* is not permitted, based on the current security policy and the
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* context encapsulated by this object.
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* @exception NullPointerException if the permission to check for is null.
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*/
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public void checkPermission(Permission perm)
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throws AccessControlException
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{
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boolean dumpDebug = false;
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if (perm == null) {
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throw new NullPointerException("permission can't be null");
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}
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if (getDebug() != null) {
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// If "codebase" is not specified, we dump the info by default.
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dumpDebug = !Debug.isOn("codebase=");
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if (!dumpDebug) {
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// If "codebase" is specified, only dump if the specified code
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// value is in the stack.
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for (int i = 0; context != null && i < context.length; i++) {
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if (context[i].getCodeSource() != null &&
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context[i].getCodeSource().getLocation() != null &&
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Debug.isOn("codebase=" + context[i].getCodeSource().getLocation().toString())) {
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dumpDebug = true;
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break;
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}
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}
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}
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dumpDebug &= !Debug.isOn("permission=") ||
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Debug.isOn("permission=" + perm.getClass().getCanonicalName());
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if (dumpDebug && Debug.isOn("stack")) {
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Thread.currentThread().dumpStack();
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}
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if (dumpDebug && Debug.isOn("domain")) {
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if (context == null) {
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debug.println("domain (context is null)");
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} else {
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for (int i=0; i< context.length; i++) {
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debug.println("domain "+i+" "+context[i]);
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}
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}
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}
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}
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/*
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* iterate through the ProtectionDomains in the context.
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* Stop at the first one that doesn't allow the
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* requested permission (throwing an exception).
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*
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*/
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/* if ctxt is null, all we had on the stack were system domains,
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or the first domain was a Privileged system domain. This
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is to make the common case for system code very fast */
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if (context == null)
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return;
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for (int i=0; i< context.length; i++) {
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if (context[i] != null && !context[i].implies(perm)) {
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if (dumpDebug) {
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debug.println("access denied " + perm);
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}
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if (Debug.isOn("failure")) {
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// Want to make sure this is always displayed for failure,
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// but do not want to display again if already displayed
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// above.
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if (!dumpDebug) {
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debug.println("access denied " + perm);
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}
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Thread.currentThread().dumpStack();
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final ProtectionDomain pd = context[i];
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final Debug db = debug;
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AccessController.doPrivileged (new PrivilegedAction<Void>() {
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public Void run() {
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db.println("domain that failed "+pd);
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return null;
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}
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});
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}
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throw new AccessControlException("access denied "+perm, perm);
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}
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}
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// allow if all of them allowed access
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if (dumpDebug) {
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debug.println("access allowed "+perm);
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}
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return;
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}
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/**
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* Take the stack-based context (this) and combine it with the
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* privileged or inherited context, if need be.
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*/
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AccessControlContext optimize() {
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// the assigned (privileged or inherited) context
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AccessControlContext acc;
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if (isPrivileged) {
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acc = privilegedContext;
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} else {
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acc = AccessController.getInheritedAccessControlContext();
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}
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// this.context could be null if only system code is on the stack;
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// in that case, ignore the stack context
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boolean skipStack = (context == null);
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// acc.context could be null if only system code was involved;
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// in that case, ignore the assigned context
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boolean skipAssigned = (acc == null || acc.context == null);
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if (acc != null && acc.combiner != null) {
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// let the assigned acc's combiner do its thing
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return goCombiner(context, acc);
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}
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// optimization: if neither have contexts; return acc if possible
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// rather than this, because acc might have a combiner
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if (skipAssigned && skipStack) {
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return this;
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}
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// optimization: if there is no stack context; there is no reason
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// to compress the assigned context, it already is compressed
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if (skipStack) {
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return acc;
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}
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int slen = context.length;
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// optimization: if there is no assigned context and the stack length
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// is less then or equal to two; there is no reason to compress the
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// stack context, it already is
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if (skipAssigned && slen <= 2) {
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return this;
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}
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// optimization: if there is a single stack domain and that domain
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// is already in the assigned context; no need to combine
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if ((slen == 1) && (context[0] == acc.context[0])) {
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return acc;
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}
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int n = (skipAssigned) ? 0 : acc.context.length;
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// now we combine both of them, and create a new context
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ProtectionDomain pd[] = new ProtectionDomain[slen + n];
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// first copy in the assigned context domains, no need to compress
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if (!skipAssigned) {
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System.arraycopy(acc.context, 0, pd, 0, n);
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}
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// now add the stack context domains, discarding nulls and duplicates
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outer:
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for (int i = 0; i < context.length; i++) {
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ProtectionDomain sd = context[i];
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if (sd != null) {
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for (int j = 0; j < n; j++) {
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if (sd == pd[j]) {
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continue outer;
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}
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}
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pd[n++] = sd;
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}
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}
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|
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431 |
// if length isn't equal, we need to shorten the array
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432 |
if (n != pd.length) {
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// optimization: if we didn't really combine anything
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if (!skipAssigned && n == acc.context.length) {
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return acc;
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} else if (skipAssigned && n == slen) {
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437 |
return this;
|
|
438 |
}
|
|
439 |
ProtectionDomain tmp[] = new ProtectionDomain[n];
|
|
440 |
System.arraycopy(pd, 0, tmp, 0, n);
|
|
441 |
pd = tmp;
|
|
442 |
}
|
|
443 |
|
|
444 |
// return new AccessControlContext(pd, false);
|
|
445 |
|
|
446 |
// Reuse existing ACC
|
|
447 |
|
|
448 |
this.context = pd;
|
|
449 |
this.combiner = null;
|
|
450 |
this.isPrivileged = false;
|
|
451 |
|
|
452 |
return this;
|
|
453 |
}
|
|
454 |
|
|
455 |
private AccessControlContext goCombiner(ProtectionDomain[] current,
|
|
456 |
AccessControlContext assigned) {
|
|
457 |
|
|
458 |
// the assigned ACC's combiner is not null --
|
|
459 |
// let the combiner do its thing
|
|
460 |
|
|
461 |
// XXX we could add optimizations to 'current' here ...
|
|
462 |
|
|
463 |
if (getDebug() != null) {
|
|
464 |
debug.println("AccessControlContext invoking the Combiner");
|
|
465 |
}
|
|
466 |
|
|
467 |
// No need to clone current and assigned.context
|
|
468 |
// combine() will not update them
|
|
469 |
ProtectionDomain[] combinedPds = assigned.combiner.combine(
|
|
470 |
current, assigned.context);
|
|
471 |
|
|
472 |
// return new AccessControlContext(combinedPds, assigned.combiner);
|
|
473 |
|
|
474 |
// Reuse existing ACC
|
|
475 |
this.context = combinedPds;
|
|
476 |
this.combiner = assigned.combiner;
|
|
477 |
this.isPrivileged = false;
|
|
478 |
|
|
479 |
return this;
|
|
480 |
}
|
|
481 |
|
|
482 |
/**
|
|
483 |
* Checks two AccessControlContext objects for equality.
|
|
484 |
* Checks that <i>obj</i> is
|
|
485 |
* an AccessControlContext and has the same set of ProtectionDomains
|
|
486 |
* as this context.
|
|
487 |
* <P>
|
|
488 |
* @param obj the object we are testing for equality with this object.
|
|
489 |
* @return true if <i>obj</i> is an AccessControlContext, and has the
|
|
490 |
* same set of ProtectionDomains as this context, false otherwise.
|
|
491 |
*/
|
|
492 |
public boolean equals(Object obj) {
|
|
493 |
if (obj == this)
|
|
494 |
return true;
|
|
495 |
|
|
496 |
if (! (obj instanceof AccessControlContext))
|
|
497 |
return false;
|
|
498 |
|
|
499 |
AccessControlContext that = (AccessControlContext) obj;
|
|
500 |
|
|
501 |
|
|
502 |
if (context == null) {
|
|
503 |
return (that.context == null);
|
|
504 |
}
|
|
505 |
|
|
506 |
if (that.context == null)
|
|
507 |
return false;
|
|
508 |
|
|
509 |
if (!(this.containsAllPDs(that) && that.containsAllPDs(this)))
|
|
510 |
return false;
|
|
511 |
|
|
512 |
if (this.combiner == null)
|
|
513 |
return (that.combiner == null);
|
|
514 |
|
|
515 |
if (that.combiner == null)
|
|
516 |
return false;
|
|
517 |
|
|
518 |
if (!this.combiner.equals(that.combiner))
|
|
519 |
return false;
|
|
520 |
|
|
521 |
return true;
|
|
522 |
}
|
|
523 |
|
|
524 |
private boolean containsAllPDs(AccessControlContext that) {
|
|
525 |
boolean match = false;
|
|
526 |
//
|
|
527 |
// ProtectionDomains within an ACC currently cannot be null
|
|
528 |
// and this is enforced by the constructor and the various
|
|
529 |
// optimize methods. However, historically this logic made attempts
|
|
530 |
// to support the notion of a null PD and therefore this logic continues
|
|
531 |
// to support that notion.
|
|
532 |
ProtectionDomain thisPd;
|
|
533 |
for (int i = 0; i < context.length; i++) {
|
|
534 |
match = false;
|
|
535 |
if ((thisPd = context[i]) == null) {
|
|
536 |
for (int j = 0; (j < that.context.length) && !match; j++) {
|
|
537 |
match = (that.context[j] == null);
|
|
538 |
}
|
|
539 |
} else {
|
|
540 |
Class thisPdClass = thisPd.getClass();
|
|
541 |
ProtectionDomain thatPd;
|
|
542 |
for (int j = 0; (j < that.context.length) && !match; j++) {
|
|
543 |
thatPd = that.context[j];
|
|
544 |
|
|
545 |
// Class check required to avoid PD exposure (4285406)
|
|
546 |
match = (thatPd != null &&
|
|
547 |
thisPdClass == thatPd.getClass() && thisPd.equals(thatPd));
|
|
548 |
}
|
|
549 |
}
|
|
550 |
if (!match) return false;
|
|
551 |
}
|
|
552 |
return match;
|
|
553 |
}
|
|
554 |
/**
|
|
555 |
* Returns the hash code value for this context. The hash code
|
|
556 |
* is computed by exclusive or-ing the hash code of all the protection
|
|
557 |
* domains in the context together.
|
|
558 |
*
|
|
559 |
* @return a hash code value for this context.
|
|
560 |
*/
|
|
561 |
|
|
562 |
public int hashCode() {
|
|
563 |
int hashCode = 0;
|
|
564 |
|
|
565 |
if (context == null)
|
|
566 |
return hashCode;
|
|
567 |
|
|
568 |
for (int i =0; i < context.length; i++) {
|
|
569 |
if (context[i] != null)
|
|
570 |
hashCode ^= context[i].hashCode();
|
|
571 |
}
|
|
572 |
return hashCode;
|
|
573 |
}
|
|
574 |
}
|