001    /* PropertyPermission.java -- permission to get and set System properties
002       Copyright (C) 1999, 2000, 2002, 2004, 2005  Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package java.util;
040    
041    import java.io.IOException;
042    import java.io.ObjectInputStream;
043    import java.io.ObjectOutputStream;
044    import java.io.ObjectStreamField;
045    import java.security.BasicPermission;
046    import java.security.Permission;
047    import 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     */
073    public 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    }