/*

 * Copyright (c) 2003, 2019, 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.

 *

 * 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.

 */

/*

 * A Launcher to launch a java process with its standard input, output,

 * and error streams connected to a socket.

 */

import java.io.IOException;

import java.net.InetAddress;

import java.net.InetSocketAddress;

import java.nio.channels.DatagramChannel;

import java.nio.channels.ServerSocketChannel;

import java.nio.channels.SocketChannel;

public class Launcher {

    static {

        System.loadLibrary("InheritedChannel");

    }

    private static native void launch0(String cmdarray[], int fd) throws IOException;

    private static void launch(String className, String options[], String args[], int fd) throws IOException {

        // java [-options] class [args...]

        int optsLen = (options == null) ? 0 : options.length;

        int argsLen = (args == null) ? 0 : args.length;

        int len = 1 + optsLen + 1 + argsLen;

        String cmdarray[] = new String[len];

        int pos = 0;

        cmdarray[pos++] = Util.javaCommand();

        if (options != null) {

            for (String opt: options) {

                cmdarray[pos++] = opt;

            }

        }

        cmdarray[pos++] = className;

        if (args != null) {

            for (String arg: args) {

                cmdarray[pos++] = arg;

            }

        }

        launch0(cmdarray, fd);

    }

    /**

     * Launch 'java' with specified class using a UnixDomainSocket pair linking calling

     * process to the child VM. UnixDomainSocket is a simplified interface to PF_UNIX sockets

     * which supports byte a time reads and writes.

     */

    public static UnixDomainSocket launchWithUnixDomainSocket(String className) throws IOException {

        UnixDomainSocket[] socks = UnixDomainSocket.socketpair();

        launch(className, null, null, socks[0].fd());

        socks[0].close();

        return socks[1];

    }

    /**

     * Launch specified class with an AF_UNIX socket created externally, and one String arg to child VM

     */

    public static void launchWithUnixDomainSocket(String className, UnixDomainSocket socket, String arg) throws IOException {

        String[] args = new String[1];

        args[0] = arg;

        launch(className, null, args, socket.fd());

    }

    /*

     * Launch 'java' with specified class with the specified arguments (may be null).

     * The launched process will inherit a connected TCP socket. The remote endpoint

     * will be the SocketChannel returned by this method.

     */

    public static SocketChannel launchWithSocketChannel(String className, String options[], String args[]) throws IOException {

        ServerSocketChannel ssc = ServerSocketChannel.open();

        InetSocketAddress isa = new InetSocketAddress(InetAddress.getLocalHost(),

                                                      ssc.socket().getLocalPort());

        SocketChannel sc1 = SocketChannel.open(isa);

        SocketChannel sc2 = ssc.accept();

        launch(className, options, args, Util.getFD(sc2));

        sc2.close();

        ssc.close();

        return sc1;

    }

    public static SocketChannel launchWithSocketChannel(String className, String args[]) throws IOException {

        return launchWithSocketChannel(className, null, args);

    }

    public static SocketChannel launchWithSocketChannel(String className) throws IOException {

        return launchWithSocketChannel(className, null);

    }

    /*

     * Launch 'java' with specified class with the specified arguments (may be null).

     * The launched process will inherited a TCP listener socket.

     * Once launched this method tries to connect to service. If a connection

     * can be established a SocketChannel, connected to the service, is returned.

     */

    public static SocketChannel launchWithServerSocketChannel(String className, String options[], String args[])

        throws IOException

    {

        ServerSocketChannel ssc = ServerSocketChannel.open();

        int port = ssc.socket().getLocalPort();

        launch(className, options, args, Util.getFD(ssc));

        ssc.close();

        InetSocketAddress isa = new InetSocketAddress(InetAddress.getLocalHost(), port);

        return SocketChannel.open(isa);

    }

    public static SocketChannel launchWithServerSocketChannel(String className, String args[]) throws IOException {

        return launchWithServerSocketChannel(className, null, args);

    }

    public static SocketChannel launchWithServerSocketChannel(String className) throws IOException {

        return launchWithServerSocketChannel(className, null);

    }

    /*

     * Launch 'java' with specified class with the specified arguments (may be null).

     * The launch process will inherited a bound UDP socket.

     * Once launched this method creates a DatagramChannel and "connects

     * it to the service. The created DatagramChannel is then returned.

     * As it is connected any packets sent from the socket will be

     * sent to the service.

     */

    public static DatagramChannel launchWithDatagramChannel(String className, String options[], String args[])

        throws IOException

    {

        DatagramChannel dc = DatagramChannel.open();

        int port = dc.socket().getLocalPort();

        launch(className, options, args, Util.getFD(dc));

        dc.close();

        dc = DatagramChannel.open();

        InetSocketAddress isa = new InetSocketAddress(address, port);

        dc.connect(isa);

        return dc;

    }

    public static DatagramChannel launchWithDatagramChannel(String className, String args[]) throws IOException {

        return launchWithDatagramChannel(className, null, args);

    }

    public static DatagramChannel launchWithDatagramChannel(String className) throws IOException {

        return launchWithDatagramChannel(className, null);

    }

}