libjava/java/util/PropertyPermission.java

   1 /* PropertyPermission.java -- permission to get and set System properties
   2    Copyright (C) 1999, 2000, 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.util;
  40
  41 import java.io.IOException;
  42 import java.io.ObjectInputStream;
  43 import java.io.ObjectOutputStream;
  44 import java.io.ObjectStreamField;
  45 import java.security.BasicPermission;
  46 import java.security.Permission;
  47 import java.security.PermissionCollection;
  48
  49 /**
  50  * This class represents the permission to access and modify a property.<br>
  51  *
  52  * The name is the name of the property, e.g. xxx.  You can also
  53  * use an asterisk "*" as described in BasicPermission.<br>
  54  *
  55  * The action string is a comma-separated list of keywords.  There are
  56  * two possible actions:
  57  * <dl>
  58  * <dt>read</dt>
  59  * <dd>Allows to read the property via <code>System.getProperty</code>.</dd>
  60  * <dt>write</dt>
  61  * <dd>Allows to write the property via <code>System.setProperty</code>.</dd>
  62  * </dl>
  63  *
  64  * The action string is case insensitive (it is converted to lower case).
  65  *
  66  * @see Permission
  67  * @see BasicPermission
  68  * @see SecurityManager
  69  * @author Jochen Hoenicke
  70  * @since 1.2
  71  * @status updated to 1.4
  72  */
  73 public final class PropertyPermission extends BasicPermission
  74 {
  75   /**
  76    * PropertyPermission uses a more efficient representation than the
  77    * serialized form; this documents the difference.
  78    *
  79    * @serialField action String the action string
  80    */
  81   private static final ObjectStreamField[] serialPersistentFields =
  82   {
  83     new ObjectStreamField("action", String.class)
  84   };
  85
  86   /**
  87    * Compatible with JDK 1.2+.
  88    */
  89   private static final long serialVersionUID = 885438825399942851L;
  90
  91   /** Permission to read. */
  92   private static final int READ = 1;
  93   /** Permission to write. */
  94   private static final int WRITE = 2;
  95
  96   /** The set of actions permitted. */
  97   // Package visible for use by PropertyPermissionCollection.
  98   transient int actions;
  99
 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 }