ojluni/src/main/java/sun/nio/ch/InheritedChannel.java - platform/libcore - Git at Google

 /*
  * Copyright (c) 2003, 2010, 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 sun.nio.ch;

 import java.lang.reflect.Constructor;
 import java.io.FileDescriptor;
 import java.io.IOException;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.nio.channels.Channel;
 import java.nio.channels.SocketChannel;
 import java.nio.channels.ServerSocketChannel;
 import java.nio.channels.DatagramChannel;
 import java.nio.channels.spi.SelectorProvider;

 class InheritedChannel {

     // the "types" of socket returned by soType0
     private static final int UNKNOWN            = -1;
     private static final int SOCK_STREAM        = 1;
     private static final int SOCK_DGRAM         = 2;

     // oflag values when opening a file
     private static final int O_RDONLY           = 0;
     private static final int O_WRONLY           = 1;
     private static final int O_RDWR             = 2;

     /*
      * In order to "detach" the standard streams we dup them to /dev/null.
      * In order to reduce the possibility of an error at close time we
      * open /dev/null early - that way we know we won't run out of file
      * descriptors at close time. This makes the close operation a
      * simple dup2 operation for each of the standard streams.
      */
     private static int devnull = -1;

     private static void detachIOStreams() {
         try {
             dup2(devnull, 0);
             dup2(devnull, 1);
             dup2(devnull, 2);
         } catch (IOException ioe) {
             // this shouldn't happen
             throw new InternalError();
         }
     }

     /*
      * Override the implCloseSelectableChannel for each channel type - this
      * allows us to "detach" the standard streams after closing and ensures
      * that the underlying socket really closes.
      */
     public static class InheritedSocketChannelImpl extends SocketChannelImpl {

         InheritedSocketChannelImpl(SelectorProvider sp,
                                    FileDescriptor fd,
                                    InetSocketAddress remote)
             throws IOException
         {
             super(sp, fd, remote);
         }

         protected void implCloseSelectableChannel() throws IOException {
             super.implCloseSelectableChannel();
             detachIOStreams();
         }
     }

     public static class InheritedServerSocketChannelImpl extends
         ServerSocketChannelImpl {

         InheritedServerSocketChannelImpl(SelectorProvider sp,
                                          FileDescriptor fd)
             throws IOException
         {
             super(sp, fd, true);
         }

         protected void implCloseSelectableChannel() throws IOException {
             super.implCloseSelectableChannel();
             detachIOStreams();
         }

     }

     public static class InheritedDatagramChannelImpl extends
         DatagramChannelImpl {

         InheritedDatagramChannelImpl(SelectorProvider sp,
                                      FileDescriptor fd)
             throws IOException
         {
             super(sp, fd);
         }

         protected void implCloseSelectableChannel() throws IOException {
             super.implCloseSelectableChannel();
             detachIOStreams();
         }
     }

     /*
      * If there's a SecurityManager then check for the appropriate
      * RuntimePermission.
      */
     private static void checkAccess(Channel c) {
         SecurityManager sm = System.getSecurityManager();
         if (sm != null) {
             sm.checkPermission(
                 new RuntimePermission("inheritedChannel")
             );
         }
     }


     /*
      * If standard inherited channel is connected to a socket then return a Channel
      * of the appropriate type based standard input.
      */
     private static Channel createChannel() throws IOException {

         // dup the file descriptor - we do this so that for two reasons :-
         // 1. Avoids any timing issues with FileDescriptor.in being closed
         //    or redirected while we create the channel.
         // 2. Allows streams based on file descriptor 0 to co-exist with
         //    the channel (closing one doesn't impact the other)

         int fdVal = dup(0);

         // Examine the file descriptor - if it's not a socket then we don't
         // create a channel so we release the file descriptor.

         int st;
         st = soType0(fdVal);
         if (st != SOCK_STREAM && st != SOCK_DGRAM) {
             close0(fdVal);
             return null;
         }


         // Next we create a FileDescriptor for the dup'ed file descriptor
         // Have to use reflection and also make assumption on how FD
         // is implemented.

         Class paramTypes[] = { int.class };
         Constructor ctr = Reflect.lookupConstructor("java.io.FileDescriptor",
                                                     paramTypes);
         Object args[] = { new Integer(fdVal) };
         FileDescriptor fd = (FileDescriptor)Reflect.invoke(ctr, args);


         // Now create the channel. If the socket is a streams socket then
         // we see if tthere is a peer (ie: connected). If so, then we
         // create a SocketChannel, otherwise a ServerSocketChannel.
         // If the socket is a datagram socket then create a DatagramChannel

         SelectorProvider provider = SelectorProvider.provider();
         assert provider instanceof sun.nio.ch.SelectorProviderImpl;

         Channel c;
         if (st == SOCK_STREAM) {
             InetAddress ia = peerAddress0(fdVal);
             if (ia == null) {
                c = new InheritedServerSocketChannelImpl(provider, fd);
             } else {
                int port = peerPort0(fdVal);
                assert port > 0;
                InetSocketAddress isa = new InetSocketAddress(ia, port);
                c = new InheritedSocketChannelImpl(provider, fd, isa);
             }
         } else {
             c = new InheritedDatagramChannelImpl(provider, fd);
         }
         return c;
     }

     private static boolean haveChannel = false;
     private static Channel channel = null;

     /*
      * Returns a Channel representing the inherited channel if the
      * inherited channel is a stream connected to a network socket.
      */
     public static synchronized Channel getChannel() throws IOException {
         if (devnull < 0) {
             devnull = open0("/dev/null", O_RDWR);
         }

         // If we don't have the channel try to create it
         if (!haveChannel) {
             channel = createChannel();
             haveChannel = true;
         }

         // if there is a channel then do the security check before
         // returning it.
         if (channel != null) {
             checkAccess(channel);
         }
         return channel;
     }


     // -- Native methods --

     private static native int dup(int fd) throws IOException;
     private static native void dup2(int fd, int fd2) throws IOException;
     private static native int open0(String path, int oflag) throws IOException;
     private static native void close0(int fd) throws IOException;
     private static native int soType0(int fd);
     private static native InetAddress peerAddress0(int fd);
     private static native int peerPort0(int fd);

     static {
         Util.load();
     }
 }
	/*
	* Copyright (c) 2003, 2010, 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 sun.nio.ch;

	import java.lang.reflect.Constructor;
	import java.io.FileDescriptor;
	import java.io.IOException;
	import java.net.InetAddress;
	import java.net.InetSocketAddress;
	import java.nio.channels.Channel;
	import java.nio.channels.SocketChannel;
	import java.nio.channels.ServerSocketChannel;
	import java.nio.channels.DatagramChannel;
	import java.nio.channels.spi.SelectorProvider;

	class InheritedChannel {

	// the "types" of socket returned by soType0
	private static final int UNKNOWN = -1;
	private static final int SOCK_STREAM = 1;
	private static final int SOCK_DGRAM = 2;

	// oflag values when opening a file
	private static final int O_RDONLY = 0;
	private static final int O_WRONLY = 1;
	private static final int O_RDWR = 2;

	/*
	* In order to "detach" the standard streams we dup them to /dev/null.
	* In order to reduce the possibility of an error at close time we
	* open /dev/null early - that way we know we won't run out of file
	* descriptors at close time. This makes the close operation a
	* simple dup2 operation for each of the standard streams.
	*/
	private static int devnull = -1;

	private static void detachIOStreams() {
	try {
	dup2(devnull, 0);
	dup2(devnull, 1);
	dup2(devnull, 2);
	} catch (IOException ioe) {
	// this shouldn't happen
	throw new InternalError();
	}
	}

	/*
	* Override the implCloseSelectableChannel for each channel type - this
	* allows us to "detach" the standard streams after closing and ensures
	* that the underlying socket really closes.
	*/
	public static class InheritedSocketChannelImpl extends SocketChannelImpl {

	InheritedSocketChannelImpl(SelectorProvider sp,
	FileDescriptor fd,
	InetSocketAddress remote)
	throws IOException
	{
	super(sp, fd, remote);
	}

	protected void implCloseSelectableChannel() throws IOException {
	super.implCloseSelectableChannel();
	detachIOStreams();
	}
	}

	public static class InheritedServerSocketChannelImpl extends
	ServerSocketChannelImpl {

	InheritedServerSocketChannelImpl(SelectorProvider sp,
	FileDescriptor fd)
	throws IOException
	{
	super(sp, fd, true);
	}

	protected void implCloseSelectableChannel() throws IOException {
	super.implCloseSelectableChannel();
	detachIOStreams();
	}

	}

	public static class InheritedDatagramChannelImpl extends
	DatagramChannelImpl {

	InheritedDatagramChannelImpl(SelectorProvider sp,
	FileDescriptor fd)
	throws IOException
	{
	super(sp, fd);
	}

	protected void implCloseSelectableChannel() throws IOException {
	super.implCloseSelectableChannel();
	detachIOStreams();
	}
	}

	/*
	* If there's a SecurityManager then check for the appropriate
	* RuntimePermission.
	*/
	private static void checkAccess(Channel c) {
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	sm.checkPermission(
	new RuntimePermission("inheritedChannel")
	);
	}
	}


	/*
	* If standard inherited channel is connected to a socket then return a Channel
	* of the appropriate type based standard input.
	*/
	private static Channel createChannel() throws IOException {

	// dup the file descriptor - we do this so that for two reasons :-
	// 1. Avoids any timing issues with FileDescriptor.in being closed
	// or redirected while we create the channel.
	// 2. Allows streams based on file descriptor 0 to co-exist with
	// the channel (closing one doesn't impact the other)

	int fdVal = dup(0);

	// Examine the file descriptor - if it's not a socket then we don't
	// create a channel so we release the file descriptor.

	int st;
	st = soType0(fdVal);
	if (st != SOCK_STREAM && st != SOCK_DGRAM) {
	close0(fdVal);
	return null;
	}


	// Next we create a FileDescriptor for the dup'ed file descriptor
	// Have to use reflection and also make assumption on how FD
	// is implemented.

	Class paramTypes[] = { int.class };
	Constructor ctr = Reflect.lookupConstructor("java.io.FileDescriptor",
	paramTypes);
	Object args[] = { new Integer(fdVal) };
	FileDescriptor fd = (FileDescriptor)Reflect.invoke(ctr, args);


	// Now create the channel. If the socket is a streams socket then
	// we see if tthere is a peer (ie: connected). If so, then we
	// create a SocketChannel, otherwise a ServerSocketChannel.
	// If the socket is a datagram socket then create a DatagramChannel

	SelectorProvider provider = SelectorProvider.provider();
	assert provider instanceof sun.nio.ch.SelectorProviderImpl;

	Channel c;
	if (st == SOCK_STREAM) {
	InetAddress ia = peerAddress0(fdVal);
	if (ia == null) {
	c = new InheritedServerSocketChannelImpl(provider, fd);
	} else {
	int port = peerPort0(fdVal);
	assert port > 0;
	InetSocketAddress isa = new InetSocketAddress(ia, port);
	c = new InheritedSocketChannelImpl(provider, fd, isa);
	}
	} else {
	c = new InheritedDatagramChannelImpl(provider, fd);
	}
	return c;
	}

	private static boolean haveChannel = false;
	private static Channel channel = null;

	/*
	* Returns a Channel representing the inherited channel if the
	* inherited channel is a stream connected to a network socket.
	*/
	public static synchronized Channel getChannel() throws IOException {
	if (devnull < 0) {
	devnull = open0("/dev/null", O_RDWR);
	}

	// If we don't have the channel try to create it
	if (!haveChannel) {
	channel = createChannel();
	haveChannel = true;
	}

	// if there is a channel then do the security check before
	// returning it.
	if (channel != null) {
	checkAccess(channel);
	}
	return channel;
	}


	// -- Native methods --

	private static native int dup(int fd) throws IOException;
	private static native void dup2(int fd, int fd2) throws IOException;
	private static native int open0(String path, int oflag) throws IOException;
	private static native void close0(int fd) throws IOException;
	private static native int soType0(int fd);
	private static native InetAddress peerAddress0(int fd);
	private static native int peerPort0(int fd);

	static {
	Util.load();
	}
	}