/* JdwpString.java -- utility class to read and write jdwp strings
   Copyright (C) 2005 Free Software Foundation
 
This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
 
GNU Classpath 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
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */

package gnu.classpath.jdwp.util;

import gnu.classpath.jdwp.exception.JdwpInternalErrorException;

import java.io.DataOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;

/**
 * A class to compute the JDWP representation of Strings.
 * 
 * @author Aaron Luchko <aluchko@redhat.com>
 */
public class JdwpString
{

  /**
   * Write this String to the outStream as a string understood by jdwp.
   * 
   * @param os write the String here
   * @param string the String to write
   * @throws IOException
   */
  public static void writeString(DataOutputStream os, String string)
      throws IOException
  {
    // Get the bytes of the string as a string in UTF-8
    byte[] strBytes = string.getBytes("UTF-8");
    os.writeInt(strBytes.length);
    os.write(strBytes);
  }

  /**
   * Read a jdwp style string from the ByteBuffer.
   * 
   * @param bb contains the string
   * @return the String that was read
   * @throws JdwpInternalErrorException bb didn't contain a value UTF-8 string
   */
  public static String readString(ByteBuffer bb)
      throws JdwpInternalErrorException
  {
    int length = bb.getInt();
    byte[] strBytes = new byte[length];
    bb.get(strBytes);
    try
      {
        return new String(strBytes, "UTF-8");
      }
    catch (UnsupportedEncodingException ex)
      {
        // Any string from the VM should be in UTF-8 so an encoding error
        // shouldn't be possible
        throw new JdwpInternalErrorException(ex);
      }
  }
}