libjava/java/lang/VMSecurityManager.java

   1 /*
   2  * java.lang.SecurityManager: part of the Java Class Libraries project.
   3  * Copyright (C) 1998, 2001, 2002 Free Software Foundation
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Library General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Library General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Library General Public
  16  * License along with this library; if not, write to the
  17  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18  * Boston, MA  02111-1307, USA.
  19  */
  20
  21 package java.lang;
  22
  23 import java.net.*;
  24 import java.util.*;
  25 import java.io.*;
  26
  27 /**
  28  ** VMSecurityManager is a helper class for SecurityManager the VM must
  29  ** implement.
  30  **
  31  ** @author  John Keiser
  32  ** @version 1.1.0, 31 May 1998
  33  **/
  34 class VMSecurityManager
  35 {
  36   /** Get a list of all the classes currently executing
  37    ** methods on the Java stack.  getClassContext()[0] is
  38    ** the currently executing method
  39    ** <STRONG>Spec Note:</STRONG> does not say whether
  40    ** the stack will include the getClassContext() call or
  41    ** the one just before it.
  42    **
  43    ** @return an array containing all the methods on classes
  44    **         on the Java execution stack.
  45    **/
  46   static native Class[] getClassContext();
  47
  48   /** Get the current ClassLoader--the one nearest to the
  49    ** top of the stack.
  50    ** @return the current ClassLoader.
  51    **/
  52   static ClassLoader currentClassLoader()
  53   {
  54     // The docs above are wrong.  See the online docs.
  55     // FIXME this implementation is a bit wrong too -- the docs say we
  56     // must also consider ancestors of the system class loader.
  57     ClassLoader systemClassLoader = VMClassLoader.getSystemClassLoader();
  58     Class[] classStack = getClassContext ();
  59     for (int i = 0; i < classStack.length; i++)
  60       {
  61         ClassLoader loader = classStack[i].getClassLoader();
  62         if (loader != null && loader != systemClassLoader)
  63           return loader;
  64       }
  65
  66     return null;
  67   }
  68 }