libjava/classpath/java/util/PropertyPermissionCollection.java

   1 /* PropertyPermissionCollection.java -- a collection of PropertyPermissions
   2    Copyright (C) 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., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 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.util;
  40
  41 import java.security.Permission;
  42 import java.security.PermissionCollection;
  43
  44 /**
  45  * This class provides the implementation for
  46  * <code>PropertyPermission.newPermissionCollection()</code>. It only accepts
  47  * PropertyPermissions, and correctly implements <code>implies</code>. It
  48  * is synchronized, as specified in the superclass.
  49  *
  50  * @author Eric Blake (ebb9@email.byu.edu)
  51  * @status an undocumented class, but this matches Sun's serialization
  52  */
  53 class PropertyPermissionCollection extends PermissionCollection
  54 {
  55   /**
  56    * Compatible with JDK 1.4.
  57    */
  58   private static final long serialVersionUID = 7015263904581634791L;
  59
  60   /**
  61    * The permissions.
  62    *
  63    * @serial the table of permissions in the collection
  64    */
  65   private final Hashtable permissions = new Hashtable();
  66
  67   /**
  68    * A flag to detect if "*" is in the collection.
  69    *
  70    * @serial true if "*" is in the collection
  71    */
  72   private boolean all_allowed;
  73
  74   /**
  75    * Adds a PropertyPermission to this collection.
  76    *
  77    * @param permission the permission to add
  78    * @throws IllegalArgumentException if permission is not a PropertyPermission
  79    * @throws SecurityException if collection is read-only
  80    */
  81   public void add(Permission permission)
  82   {
  83     if (isReadOnly())
  84       throw new SecurityException("readonly");
  85     if (! (permission instanceof PropertyPermission))
  86       throw new IllegalArgumentException();
  87     PropertyPermission pp = (PropertyPermission) permission;
  88     String name = pp.getName();
  89     if (name.equals("*"))
  90         all_allowed = true;
  91     PropertyPermission old = (PropertyPermission) permissions.get(name);
  92     if (old != null)
  93       {
  94         if ((pp.actions | old.actions) == old.actions)
  95           pp = old; // Old implies pp.
  96         else if ((pp.actions | old.actions) != pp.actions)
  97           // Here pp doesn't imply old; the only case left is both actions.
  98           pp = new PropertyPermission(name, "read,write");
  99       }
 100     permissions.put(name, pp);
 101   }
 102
 103   /**
 104    * Returns true if this collection implies the given permission. This even
 105    * returns true for this case:
 106    *
 107    * <pre>
 108    * collection.add(new PropertyPermission("a.*", "read"));
 109    * collection.add(new PropertyPermission("a.b.*", "write"));
 110    * collection.implies(new PropertyPermission("a.b.c", "read,write"));
 111    * </pre>
 112    *
 113    * @param permission the permission to check
 114    * @return true if it is implied by this
 115    */
 116   public boolean implies(Permission permission)
 117   {
 118     if (! (permission instanceof PropertyPermission))
 119       return false;
 120     PropertyPermission toImply = (PropertyPermission) permission;
 121     int actions = toImply.actions;
 122
 123     if (all_allowed)
 124       {
 125         int all_actions = ((PropertyPermission) permissions.get("*")).actions;
 126         actions &= ~all_actions;
 127         if (actions == 0)
 128           return true;
 129       }
 130
 131     String name = toImply.getName();
 132     if (name.equals("*"))
 133       return false;
 134
 135     int prefixLength = name.length();
 136     if (name.endsWith("*"))
 137       prefixLength -= 2;
 138
 139     while (true)
 140       {
 141         PropertyPermission forName =
 142           (PropertyPermission) permissions.get(name);
 143         if (forName != null)
 144           {
 145             actions &= ~forName.actions;
 146             if (actions == 0)
 147               return true;
 148           }
 149
 150         prefixLength = name.lastIndexOf('.', prefixLength - 1);
 151         if (prefixLength < 0)
 152           return false;
 153         name = name.substring(0, prefixLength + 1) + '*';
 154       }
 155   }
 156
 157   /**
 158    * Enumerate over the collection.
 159    *
 160    * @return an enumeration of the collection contents
 161    */
 162   public Enumeration elements()
 163   {
 164     return permissions.elements();
 165   }
 166 }