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/*

 * java.lang.SecurityManager: part of the Java Class Libraries project.

 * Copyright (C) 1998, 2001, 2002, 2005 Free Software Foundation

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,

 * Boston, MA  02110-1301, USA.

 */

package java.lang;

import java.net.*;

import java.util.*;

import java.io.*;

/**

 ** VMSecurityManager is a helper class for SecurityManager the VM must

 ** implement.

 **

 ** @author  John Keiser

 ** @version 1.1.0, 31 May 1998

 **/

class VMSecurityManager

{

  /** Get a list of all the classes currently executing

   ** methods on the Java stack.  getClassContext()[0] is

   ** the currently executing method

   ** <STRONG>Spec Note:</STRONG> does not say whether

   ** the stack will include the getClassContext() call or

   ** the one just before it.

   **

   ** @return an array containing all the methods on classes

   **         on the Java execution stack.

   **/

  static native Class[] getClassContext(Class caller);

  /** Get the current ClassLoader--the one nearest to the

   ** top of the stack.

   ** @return the current ClassLoader.

   **/

  static ClassLoader currentClassLoader(Class caller)

  {

    // The docs above are wrong.  See the online docs.

    // FIXME this implementation is a bit wrong too -- the docs say we

    // must also consider ancestors of the system class loader.

    ClassLoader systemClassLoader = ClassLoader.systemClassLoader;

    Class[] classStack = getClassContext (caller);

    for (int i = 0; i < classStack.length; i++)

      {

        ClassLoader loader = classStack[i].getClassLoader();

        if (loader != null && loader != systemClassLoader)

          return loader;

      }

    return null;

  }

}