1 /*
   2  * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.security;
  27 
  28 /**
  29  * A GuardedObject is an object that is used to protect access to
  30  * another object.
  31  *
  32  * <p>A GuardedObject encapsulates a target object and a Guard object,
  33  * such that access to the target object is possible
  34  * only if the Guard object allows it.
  35  * Once an object is encapsulated by a GuardedObject,
  36  * access to that object is controlled by the {@code getObject}
  37  * method, which invokes the
  38  * {@code checkGuard} method on the Guard object that is
  39  * guarding access. If access is not allowed,
  40  * an exception is thrown.
  41  *
  42  * @see Guard
  43  * @see Permission
  44  *
  45  * @author Roland Schemers
  46  * @author Li Gong
  47  * @since 1.2
  48  */
  49 
  50 public class GuardedObject implements java.io.Serializable {
  51 
  52     @java.io.Serial
  53     private static final long serialVersionUID = -5240450096227834308L;
  54 
  55     private Object object; // the object we are guarding
  56     private Guard guard;   // the guard
  57 
  58     /**
  59      * Constructs a GuardedObject using the specified object and guard.
  60      * If the Guard object is null, then no restrictions will
  61      * be placed on who can access the object.
  62      *
  63      * @param object the object to be guarded.
  64      *
  65      * @param guard the Guard object that guards access to the object.
  66      */
  67 
  68     public GuardedObject(Object object, Guard guard)
  69     {
  70         this.guard = guard;
  71         this.object = object;
  72     }
  73 
  74     /**
  75      * Retrieves the guarded object, or throws an exception if access
  76      * to the guarded object is denied by the guard.
  77      *
  78      * @return the guarded object.
  79      *
  80      * @exception SecurityException if access to the guarded object is
  81      * denied.
  82      */
  83     public Object getObject()
  84         throws SecurityException
  85     {
  86         if (guard != null)
  87             guard.checkGuard(object);
  88 
  89         return object;
  90     }
  91 
  92     /**
  93      * Writes this object out to a stream (i.e., serializes it).
  94      * We check the guard if there is one.
  95      */
  96     @java.io.Serial
  97     private void writeObject(java.io.ObjectOutputStream oos)
  98         throws java.io.IOException
  99     {
 100         if (guard != null)
 101             guard.checkGuard(object);
 102 
 103         oos.defaultWriteObject();
 104     }
 105 }