/*

 * Copyright (c) 1999, 2012, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

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

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

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

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.tools.jdi;

import com.sun.jdi.*;

import com.sun.jdi.connect.*;

import com.sun.jdi.connect.spi.*;

import java.io.IOException;

class SharedMemoryConnection extends Connection {

    private long id;

    private Object receiveLock = new Object();

    private Object sendLock = new Object();

    private Object closeLock = new Object();

    private boolean closed = false;

    private native byte receiveByte0(long id) throws IOException;

    private native void sendByte0(long id, byte b) throws IOException;

    private native void close0(long id);

    private native byte[] receivePacket0(long id)throws IOException;

    private native void sendPacket0(long id, byte b[]) throws IOException;

    // handshake with the target VM

    void handshake(long handshakeTimeout) throws IOException {

        byte[] hello = "JDWP-Handshake".getBytes("UTF-8");

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

            sendByte0(id, hello[i]);

        }

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

            byte b = receiveByte0(id);

            if (b != hello[i]) {

                throw new IOException("handshake failed - unrecognized message from target VM");

            }

        }

    }

    SharedMemoryConnection(long id) throws IOException {

        this.id = id;

    }

    public void close() {

        synchronized (closeLock) {

            if (!closed) {

                close0(id);

                closed = true;

            }

        }

    }

    public boolean isOpen() {

        synchronized (closeLock) {

            return !closed;

        }

    }

    public byte[] readPacket() throws IOException {

        if (!isOpen()) {

            throw new ClosedConnectionException("Connection closed");

        }

        byte b[];

        try {

            // only one thread may be reading at a time

            synchronized (receiveLock) {

                b  = receivePacket0(id);

            }

        } catch (IOException ioe) {

            if (!isOpen()) {

                throw new ClosedConnectionException("Connection closed");

            } else {

                throw ioe;

            }

        }

        return b;

    }

    public void writePacket(byte b[]) throws IOException {

        if (!isOpen()) {

            throw new ClosedConnectionException("Connection closed");

        }

        /*

         * Check the packet size

         */

        if (b.length < 11) {

            throw new IllegalArgumentException("packet is insufficient size");

        }

        int b0 = b[0] & 0xff;

        int b1 = b[1] & 0xff;

        int b2 = b[2] & 0xff;

        int b3 = b[3] & 0xff;

        int len = ((b0 << 24) | (b1 << 16) | (b2 << 8) | (b3 << 0));

        if (len < 11) {

            throw new IllegalArgumentException("packet is insufficient size");

        }

        /*

         * Check that the byte array contains the complete packet

         */

        if (len > b.length) {

            throw new IllegalArgumentException("length mis-match");

        }

        try {

            // only one thread may be writing at a time

            synchronized(sendLock) {

                sendPacket0(id, b);

            }

        } catch (IOException ioe) {

            if (!isOpen()) {

               throw new ClosedConnectionException("Connection closed");

            } else {

               throw ioe;

            }

        }

    }

}