001/* AllPermission.java -- Permission to do anything
002   Copyright (C) 1998, 2001, 2002, 2004, 2005  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.security;
040
041import gnu.java.util.EmptyEnumeration;
042
043import java.util.Collections;
044import java.util.Enumeration;
045
046/**
047 * This class is a permission that implies all other permissions.  Granting
048 * this permission effectively grants all others.  Extreme caution should
049 * be exercised in granting this permission.
050 *
051 * @author Aaron M. Renn (arenn@urbanophile.com)
052 * @author Eric Blake (ebb9@email.byu.edu)
053 * @see AccessController
054 * @see Permissions
055 * @see SecurityManager
056 * @since 1.1
057 * @status updated to 1.4
058 */
059public final class AllPermission extends Permission
060{
061  /**
062   * Compatible with JDK 1.1+.
063   */
064  private static final long serialVersionUID = -2916474571451318075L;
065
066  /**
067   * Create a new AllPermission object.
068   */
069  public AllPermission()
070  {
071    super("*");
072  }
073
074  /**
075   * Create a new AllPermission object. The parameters are ignored, as all
076   * permission implies ALL PERMISSION.
077   *
078   * @param name ignored
079   * @param actions ignored
080   */
081  public AllPermission(String name, String actions)
082  {
083    super("*");
084  }
085
086  /**
087   * This method always returns <code>true</code> to indicate that this
088   * permission always implies that any other permission is also granted.
089   *
090   * @param perm ignored
091   * @return true, the permission is implied
092   */
093  public boolean implies(Permission perm)
094  {
095    return true;
096  }
097
098  /**
099   * 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