libjava/java/security/AllPermission.java

   1 /* AllPermission.java -- Permission to do anything
   2    Copyright (C) 1998, 2001, 2002, 2004, 2005  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.security;
  40
  41 import gnu.java.util.EmptyEnumeration;
  42
  43 import java.util.Collections;
  44 import java.util.Enumeration;
  45
  46 /**
  47  * This class is a permission that implies all other permissions.  Granting
  48  * this permission effectively grants all others.  Extreme caution should
  49  * be exercised in granting this permission.
  50  *
  51  * @author Aaron M. Renn (arenn@urbanophile.com)
  52  * @author Eric Blake (ebb9@email.byu.edu)
  53  * @see AccessController
  54  * @see Permissions
  55  * @see SecurityManager
  56  * @since 1.1
  57  * @status updated to 1.4
  58  */
  59 public final class AllPermission extends Permission
  60 {
  61   /**
  62    * Compatible with JDK 1.1+.
  63    */
  64   private static final long serialVersionUID = -2916474571451318075L;
  65
  66   /**
  67    * Create a new AllPermission object.
  68    */
  69   public AllPermission()
  70   {
  71     super("*");
  72   }
  73
  74   /**
  75    * Create a new AllPermission object. The parameters are ignored, as all
  76    * permission implies ALL PERMISSION.
  77    *
  78    * @param name ignored
  79    * @param actions ignored
  80    */
  81   public AllPermission(String name, String actions)
  82   {
  83     super("*");
  84   }
  85
  86   /**
  87    * This method always returns <code>true</code> to indicate that this
  88    * permission always implies that any other permission is also granted.
  89    *
  90    * @param perm ignored
  91    * @return true, the permission is implied
  92    */
  93   public boolean implies(Permission perm)
  94   {
  95     return true;
  96   }
  97
  98   /**
  99    * Checks an object for equality. All AllPermissions are equal.
 100    *
 101    * @param obj the <code>Object</code> to test for equality
 102    */
 103   public boolean equals(Object obj)
 104   {
 105     return obj instanceof AllPermission;
 106   }
 107
 108   /**
 109    * This method returns a hash code for this object. This returns 1.
 110    *
 111    * @return a hash value for this object
 112    */
 113   public int hashCode()
 114   {
 115     return 1;
 116   }
 117
 118   /**
 119    * This method returns the list of actions associated with this object.
 120    * This will always be the empty string ("") for this class.
 121    *
 122    * @return the action list
 123    */
 124   public String getActions()
 125   {
 126     return "";
 127   }
 128
 129   /**
 130    * Returns a PermissionCollection which can hold AllPermission.
 131    *
 132    * @return a permission collection
 133    */
 134   public PermissionCollection newPermissionCollection()
 135   {
 136     return new AllPermissionCollection();
 137   }
 138
 139   /**
 140    * Implements AllPermission.newPermissionCollection, and obeys serialization
 141    * of JDK.
 142    *
 143    * @author Eric Blake (ebb9@email.byu.edu)
 144    */
 145   private static final class AllPermissionCollection extends PermissionCollection
 146   {
 147     /**
 148      * Compatible with JDK 1.1+.
 149      */
 150     private static final long serialVersionUID = -4023755556366636806L;
 151
 152     /**
 153      * Whether an AllPermission has been added to the collection.
 154      *
 155      * @serial if all permission is in the collection yet
 156      */
 157     private boolean all_allowed;
 158
 159     /**
 160      * Add an AllPermission.
 161      *
 162      * @param perm the permission to add
 163      * @throws IllegalArgumentException if perm is not an AllPermission
 164      * @throws SecurityException if the collection is read-only
 165      */
 166     public void add(Permission perm)
 167     {
 168       if (isReadOnly())
 169         throw new SecurityException();
 170       if (! (perm instanceof AllPermission))
 171         throw new IllegalArgumentException();
 172       all_allowed = true;
 173     }
 174
 175     /**
 176      * Returns true if this collection implies a permission.
 177      *
 178      * @param perm the permission to check
 179      * @return true if this collection contains an AllPermission
 180      */
 181     public boolean implies(Permission perm)
 182     {
 183       return all_allowed;
 184     }
 185
 186     /**
 187      * Returns an enumeration of the elements in the collection.
 188      *
 189      * @return the elements in the collection
 190      */
 191     public Enumeration elements()
 192     {
 193       return all_allowed
 194         ? Collections.enumeration(Collections.singleton(new AllPermission()))
 195         : EmptyEnumeration.getInstance();
 196     }
 197   } // class AllPermissionCollection
 198 } // class AllPermission