001/* PropertyPermission.java -- permission to get and set System properties
002   Copyright (C) 1999, 2000, 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.util;
040
041import java.io.IOException;
042import java.io.ObjectInputStream;
043import java.io.ObjectOutputStream;
044import java.io.ObjectStreamField;
045import java.security.BasicPermission;
046import java.security.Permission;
047import java.security.PermissionCollection;
048
049/**
050 * This class represents the permission to access and modify a property.<br>
051 *
052 * The name is the name of the property, e.g. xxx.  You can also
053 * use an asterisk "*" as described in BasicPermission.<br>
054 *
055 * The action string is a comma-separated list of keywords.  There are
056 * two possible actions:
057 * <dl>
058 * <dt>read</dt>
059 * <dd>Allows to read the property via <code>System.getProperty</code>.</dd>
060 * <dt>write</dt>
061 * <dd>Allows to write the property via <code>System.setProperty</code>.</dd>
062 * </dl>
063 *
064 * The action string is case insensitive (it is converted to lower case).
065 *
066 * @see Permission
067 * @see BasicPermission
068 * @see SecurityManager
069 * @author Jochen Hoenicke
070 * @since 1.2
071 * @status updated to 1.4
072 */
073public final class PropertyPermission extends BasicPermission
074{
075  /**
076   * PropertyPermission uses a more efficient representation than the
077   * serialized form; this documents the difference.
078   *
079   * @serialField action String the action string
080   */
081  private static final ObjectStreamField[] serialPersistentFields =
082  {
083    new ObjectStreamField("action", String.class)
084  };
085
086  /**
087   * Compatible with JDK 1.2+.
088   */
089  private static final long serialVersionUID = 885438825399942851L;
090
091  /** Permission to read. */
092  private static final int READ = 1;
093  /** Permission to write. */
094  private static final int WRITE = 2;
095
096  /** The set of actions permitted. */
097  // Package visible for use by PropertyPermissionCollection.
098  transient int actions;
099
100  /**
101   * The String forms of the actions permitted.
102   */
103  private static final String actionStrings[] =
104  {
105    "", "read", "write", "read,write"
106  };
107
108  /**
109   * Constructs a PropertyPermission with the specified property.  Possible
110   * actions are read and write, comma-separated and case-insensitive.
111   *
112   * @param name the name of the property
113   * @param actions the action string
114   * @throws NullPointerException if name is null
115   * @throws IllegalArgumentException if name string contains an
116   *         illegal wildcard or actions string contains an illegal action
117   *         (this includes a null actions string)
118   */
119  public PropertyPermission(String name, String actions)
120  {
121    super(name);
122    if (actions == null)
123      throw new IllegalArgumentException();
124    setActions(actions);
125  }
126
127  /**
128   * Parse the action string and convert actions from external to internal
129   * form.  This will set the internal actions field.
130   *
131   * @param str the action string
132   * @throws IllegalArgumentException if actions string contains an
133   *         illegal action
134   */
135  private void setActions(String str)
136  {
137    // Initialising the class java.util.Locale ...
138    //    tries to initialise the Locale.defaultLocale static
139    //    which calls System.getProperty,
140    //    which calls SecurityManager.checkPropertiesAccess,
141    //    which creates a PropertyPermission with action "read,write",
142    //    which calls setActions("read,write").
143    // If we now were to call toLowerCase on 'str',
144    //    this would call Locale.getDefault() which returns null
145    //       because Locale.defaultLocale hasn't been set yet
146    //    then toLowerCase will fail with a null pointer exception.
147    //
148    // The solution is to take a punt on 'str' being lower case, and
149    // test accordingly.  If that fails, we convert 'str' to lower case
150    // and try the tests again.
151    if ("read".equals(str))
152      actions = READ;
153    else if ("write".equals(str))
154      actions = WRITE;
155    else if ("read,write".equals(str) || "write,read".equals(str))
156      actions = READ | WRITE;
157    else
158      {
159        String lstr = str.toLowerCase();
160        if ("read".equals(lstr))
161          actions = READ;
162        else if ("write".equals(lstr))
163          actions = WRITE;
164        else if ("read,write".equals(lstr) || "write,read".equals(lstr))
165          actions = READ | WRITE;
166        else
167          throw new IllegalArgumentException("illegal action " + str);
168      }
169  }
170
171  /**
172   * Reads an object from the stream. This converts the external to the
173   * internal representation.
174   *
175   * @param s the stream to read from
176   * @throws IOException if the stream fails
177   * @throws ClassNotFoundException if reserialization fails
178   */
179  private void readObject(ObjectInputStream s)
180    throws IOException, ClassNotFoundException
181  {
182    ObjectInputStream.GetField fields = s.readFields();
183    setActions((String) fields.get("actions", null));
184  }
185
186  /**
187   * Writes an object to the stream. This converts the internal to the
188   * external representation.
189   *
190   * @param s the stram to write to
191   * @throws IOException if the stream fails
192   */
193  private void writeObject(ObjectOutputStream s) throws IOException
194  {
195    ObjectOutputStream.PutField fields = s.putFields();
196    fields.put("actions", getActions());
197    s.writeFields();
198  }
199
200  /**
201   * Check if this permission implies p.  This returns true iff all of
202   * the following conditions are true:
203   * <ul>
204   * <li> p is a PropertyPermission </li>
205   * <li> this.getName() implies p.getName(),
206   *  e.g. <code>java.*</code> implies <code>java.home</code> </li>
207   * <li> this.getActions is a subset of p.getActions </li>
208   * </ul>
209   *
210   * @param p the permission to check
211   * @return true if this permission implies p
212   */
213  public boolean implies(Permission p)
214  {
215    // BasicPermission checks for name and type.
216    if (super.implies(p))
217      {
218        // We have to check the actions.
219        PropertyPermission pp = (PropertyPermission) p;
220        return (pp.actions & ~actions) == 0;
221      }
222    return false;
223  }
224
225  /**
226   * Check to see whether this object is the same as another
227   * PropertyPermission object; this is true if it has the same name and
228   * actions.
229   *
230   * @param obj the other object
231   * @return true if the two are equivalent
232   */
233  public boolean equals(Object obj)
234  {
235    return super.equals(obj) && actions == ((PropertyPermission) obj).actions;
236  }
237
238  /**
239   * Returns the hash code for this permission.  It is equivalent to
240   * <code>getName().hashCode()</code>.
241   *
242   * @return the hash code
243   */
244  public int hashCode()
245  {
246    return super.hashCode();
247  }
248
249  /**
250   * Returns the action string.  Note that this may differ from the string
251   * given at the constructor:  The actions are converted to lowercase and
252   * may be reordered.
253   *
254   * @return one of "read", "write", or "read,write"
255   */
256  public String getActions()
257  {
258    return actionStrings[actions];
259  }
260
261  /**
262   * Returns a permission collection suitable to take
263   * PropertyPermission objects.
264   *
265   * @return a new empty PermissionCollection
266   */
267  public PermissionCollection newPermissionCollection()
268  {
269    return new PropertyPermissionCollection();
270  }
271}