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	/*
	* Copyright (c) 2000, 2021, 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.io.FileDescriptor;
	import java.io.IOException;
	import java.net.InetAddress;
	import java.net.Inet4Address;
	import java.net.InetSocketAddress;
	import java.net.ProtocolFamily;
	import java.net.Socket;
	import java.net.SocketAddress;
	import java.net.SocketException;
	import java.net.SocketOption;
	import java.net.SocketTimeoutException;
	import java.net.StandardSocketOptions;
	import java.nio.ByteBuffer;
	import java.nio.channels.AlreadyBoundException;
	import java.nio.channels.AlreadyConnectedException;
	import java.nio.channels.AsynchronousCloseException;
	import java.nio.channels.ClosedChannelException;
	import java.nio.channels.ConnectionPendingException;
	import java.nio.channels.IllegalBlockingModeException;
	import java.nio.channels.NoConnectionPendingException;
	import java.nio.channels.NotYetConnectedException;
	import java.nio.channels.SelectionKey;
	import java.nio.channels.SocketChannel;
	import java.nio.channels.spi.SelectorProvider;
	import java.nio.file.Path;
	import java.util.Collections;
	import java.util.HashSet;
	import java.util.Set;
	import java.util.Objects;
	import java.util.concurrent.locks.ReentrantLock;
	import static java.net.StandardProtocolFamily.INET;
	import static java.net.StandardProtocolFamily.INET6;
	import static java.net.StandardProtocolFamily.UNIX;

	import sun.net.ConnectionResetException;
	import sun.net.NetHooks;
	import sun.net.ext.ExtendedSocketOptions;
	import sun.net.util.SocketExceptions;

	/**
	* An implementation of SocketChannels
	*/

	class SocketChannelImpl
	extends SocketChannel
	implements SelChImpl
	{
	// Used to make native read and write calls
	private static final NativeDispatcher nd = new SocketDispatcher();

	// The protocol family of the socket
	private final ProtocolFamily family;

	// Our file descriptor object
	private final FileDescriptor fd;
	private final int fdVal;

	// Lock held by current reading or connecting thread
	private final ReentrantLock readLock = new ReentrantLock();

	// Lock held by current writing or connecting thread
	private final ReentrantLock writeLock = new ReentrantLock();

	// Lock held by any thread that modifies the state fields declared below
	// DO NOT invoke a blocking I/O operation while holding this lock!
	private final Object stateLock = new Object();

	// Input/Output closed
	private volatile boolean isInputClosed;
	private volatile boolean isOutputClosed;

	// Connection reset protected by readLock
	private boolean connectionReset;

	// -- The following fields are protected by stateLock

	// set true when exclusive binding is on and SO_REUSEADDR is emulated
	private boolean isReuseAddress;

	// State, increases monotonically
	private static final int ST_UNCONNECTED = 0;
	private static final int ST_CONNECTIONPENDING = 1;
	private static final int ST_CONNECTED = 2;
	private static final int ST_CLOSING = 3;
	private static final int ST_CLOSED = 4;
	private volatile int state; // need stateLock to change

	// IDs of native threads doing reads and writes, for signalling
	private long readerThread;
	private long writerThread;

	// Binding
	private SocketAddress localAddress;
	private SocketAddress remoteAddress;

	// Socket adaptor, created on demand
	private Socket socket;

	// -- End of fields protected by stateLock

	SocketChannelImpl(SelectorProvider sp) throws IOException {
	this(sp, Net.isIPv6Available() ? INET6 : INET);
	}

	SocketChannelImpl(SelectorProvider sp, ProtocolFamily family) throws IOException {
	super(sp);
	Objects.requireNonNull(family, "'family' is null");
	if ((family != INET) && (family != INET6) && (family != UNIX)) {
	throw new UnsupportedOperationException("Protocol family not supported");
	}
	if (family == INET6 && !Net.isIPv6Available()) {
	throw new UnsupportedOperationException("IPv6 not available");
	}

	this.family = family;
	if (family == UNIX) {
	this.fd = UnixDomainSockets.socket();
	} else {
	this.fd = Net.socket(family, true);
	}
	this.fdVal = IOUtil.fdVal(fd);
	}

	// Constructor for sockets obtained from server sockets
	//
	SocketChannelImpl(SelectorProvider sp,
	ProtocolFamily family,
	FileDescriptor fd,
	SocketAddress remoteAddress)
	throws IOException
	{
	super(sp);
	this.family = family;
	this.fd = fd;
	this.fdVal = IOUtil.fdVal(fd);
	synchronized (stateLock) {
	if (family == UNIX) {
	this.localAddress = UnixDomainSockets.localAddress(fd);
	} else {
	this.localAddress = Net.localAddress(fd);
	}
	this.remoteAddress = remoteAddress;
	this.state = ST_CONNECTED;
	}
	}

	/**
	* Returns true if this channel is to a INET or INET6 socket.
	*/
	boolean isNetSocket() {
	return (family == INET) \|\| (family == INET6);
	}

	/**
	* Returns true if this channel is to a UNIX socket.
	*/
	boolean isUnixSocket() {
	return (family == UNIX);
	}

	/**
	* Checks that the channel is open.
	*
	* @throws ClosedChannelException if channel is closed (or closing)
	*/
	private void ensureOpen() throws ClosedChannelException {
	if (!isOpen())
	throw new ClosedChannelException();
	}

	/**
	* Checks that the channel is open and connected.
	*
	* @apiNote This method uses the "state" field to check if the channel is
	* open. It should never be used in conjuncion with isOpen or ensureOpen
	* as these methods check AbstractInterruptibleChannel's closed field - that
	* field is set before implCloseSelectableChannel is called and so before
	* the state is changed.
	*
	* @throws ClosedChannelException if channel is closed (or closing)
	* @throws NotYetConnectedException if open and not connected
	*/
	private void ensureOpenAndConnected() throws ClosedChannelException {
	int state = this.state;
	if (state < ST_CONNECTED) {
	throw new NotYetConnectedException();
	} else if (state > ST_CONNECTED) {
	throw new ClosedChannelException();
	}
	}

	@Override
	public Socket socket() {
	synchronized (stateLock) {
	if (socket == null) {
	if (isNetSocket()) {
	socket = SocketAdaptor.create(this);
	} else {
	throw new UnsupportedOperationException("Not supported");
	}
	}
	return socket;
	}
	}

	@Override
	public SocketAddress getLocalAddress() throws IOException {
	synchronized (stateLock) {
	ensureOpen();
	if (isUnixSocket()) {
	return UnixDomainSockets.getRevealedLocalAddress(localAddress);
	} else {
	return Net.getRevealedLocalAddress(localAddress);
	}
	}
	}

	@Override
	public SocketAddress getRemoteAddress() throws IOException {
	synchronized (stateLock) {
	ensureOpen();
	return remoteAddress;
	}
	}

	@Override
	public <T> SocketChannel setOption(SocketOption<T> name, T value)
	throws IOException
	{
	Objects.requireNonNull(name);
	if (!supportedOptions().contains(name))
	throw new UnsupportedOperationException("'" + name + "' not supported");
	if (!name.type().isInstance(value))
	throw new IllegalArgumentException("Invalid value '" + value + "'");

	synchronized (stateLock) {
	ensureOpen();

	if (isNetSocket()) {
	if (name == StandardSocketOptions.IP_TOS) {
	// special handling for IP_TOS
	Net.setSocketOption(fd, family, name, value);
	return this;
	}
	if (name == StandardSocketOptions.SO_REUSEADDR && Net.useExclusiveBind()) {
	// SO_REUSEADDR emulated when using exclusive bind
	isReuseAddress = (Boolean) value;
	return this;
	}
	}

	// no options that require special handling
	Net.setSocketOption(fd, name, value);
	return this;
	}
	}

	@Override
	@SuppressWarnings("unchecked")
	public <T> T getOption(SocketOption<T> name)
	throws IOException
	{
	Objects.requireNonNull(name);
	if (!supportedOptions().contains(name))
	throw new UnsupportedOperationException("'" + name + "' not supported");

	synchronized (stateLock) {
	ensureOpen();

	if (isNetSocket()) {
	if (name == StandardSocketOptions.IP_TOS) {
	// special handling for IP_TOS
	return (T) Net.getSocketOption(fd, family, name);
	}
	if (name == StandardSocketOptions.SO_REUSEADDR && Net.useExclusiveBind()) {
	// SO_REUSEADDR emulated when using exclusive bind
	return (T) Boolean.valueOf(isReuseAddress);
	}
	}

	// no options that require special handling
	return (T) Net.getSocketOption(fd, name);
	}
	}

	private static class DefaultOptionsHolder {
	static final Set<SocketOption<?>> defaultInetOptions = defaultInetOptions();
	static final Set<SocketOption<?>> defaultUnixOptions = defaultUnixOptions();

	private static Set<SocketOption<?>> defaultInetOptions() {
	HashSet<SocketOption<?>> set = new HashSet<>();
	set.add(StandardSocketOptions.SO_SNDBUF);
	set.add(StandardSocketOptions.SO_RCVBUF);
	set.add(StandardSocketOptions.SO_KEEPALIVE);
	set.add(StandardSocketOptions.SO_REUSEADDR);
	if (Net.isReusePortAvailable()) {
	set.add(StandardSocketOptions.SO_REUSEPORT);
	}
	set.add(StandardSocketOptions.SO_LINGER);
	set.add(StandardSocketOptions.TCP_NODELAY);
	// additional options required by socket adaptor
	set.add(StandardSocketOptions.IP_TOS);
	set.add(ExtendedSocketOption.SO_OOBINLINE);
	set.addAll(ExtendedSocketOptions.clientSocketOptions());
	return Collections.unmodifiableSet(set);
	}

	private static Set<SocketOption<?>> defaultUnixOptions() {
	HashSet<SocketOption<?>> set = new HashSet<>();
	set.add(StandardSocketOptions.SO_SNDBUF);
	set.add(StandardSocketOptions.SO_RCVBUF);
	set.add(StandardSocketOptions.SO_LINGER);
	set.addAll(ExtendedSocketOptions.unixDomainSocketOptions());
	return Collections.unmodifiableSet(set);
	}
	}

	@Override
	public final Set<SocketOption<?>> supportedOptions() {
	if (isUnixSocket()) {
	return DefaultOptionsHolder.defaultUnixOptions;
	} else {
	return DefaultOptionsHolder.defaultInetOptions;
	}
	}

	/**
	* Marks the beginning of a read operation that might block.
	*
	* @throws ClosedChannelException if blocking and the channel is closed
	*/
	private void beginRead(boolean blocking) throws ClosedChannelException {
	if (blocking) {
	// set hook for Thread.interrupt
	begin();

	synchronized (stateLock) {
	ensureOpen();
	// record thread so it can be signalled if needed
	readerThread = NativeThread.current();
	}
	}
	}

	/**
	* Marks the end of a read operation that may have blocked.
	*
	* @throws AsynchronousCloseException if the channel was closed due to this
	* thread being interrupted on a blocking read operation.
	*/
	private void endRead(boolean blocking, boolean completed)
	throws AsynchronousCloseException
	{
	if (blocking) {
	synchronized (stateLock) {
	readerThread = 0;
	if (state == ST_CLOSING) {
	tryFinishClose();
	}
	}
	// remove hook for Thread.interrupt
	end(completed);
	}
	}

	private void throwConnectionReset() throws SocketException {
	throw new SocketException("Connection reset");
	}

	@Override
	public int read(ByteBuffer buf) throws IOException {
	Objects.requireNonNull(buf);

	readLock.lock();
	try {
	ensureOpenAndConnected();
	boolean blocking = isBlocking();
	int n = 0;
	try {
	beginRead(blocking);

	// check if connection has been reset
	if (connectionReset)
	throwConnectionReset();

	// check if input is shutdown
	if (isInputClosed)
	return IOStatus.EOF;

	n = IOUtil.read(fd, buf, -1, nd);
	if (blocking) {
	while (IOStatus.okayToRetry(n) && isOpen()) {
	park(Net.POLLIN);
	n = IOUtil.read(fd, buf, -1, nd);
	}
	}
	} catch (ConnectionResetException e) {
	connectionReset = true;
	throwConnectionReset();
	} finally {
	endRead(blocking, n > 0);
	if (n <= 0 && isInputClosed)
	return IOStatus.EOF;
	}
	return IOStatus.normalize(n);
	} finally {
	readLock.unlock();
	}
	}

	@Override
	public long read(ByteBuffer[] dsts, int offset, int length)
	throws IOException
	{
	Objects.checkFromIndexSize(offset, length, dsts.length);

	readLock.lock();
	try {
	ensureOpenAndConnected();
	boolean blocking = isBlocking();
	long n = 0;
	try {
	beginRead(blocking);

	// check if connection has been reset
	if (connectionReset)
	throwConnectionReset();

	// check if input is shutdown
	if (isInputClosed)
	return IOStatus.EOF;

	n = IOUtil.read(fd, dsts, offset, length, nd);
	if (blocking) {
	while (IOStatus.okayToRetry(n) && isOpen()) {
	park(Net.POLLIN);
	n = IOUtil.read(fd, dsts, offset, length, nd);
	}
	}
	} catch (ConnectionResetException e) {
	connectionReset = true;
	throwConnectionReset();
	} finally {
	endRead(blocking, n > 0);
	if (n <= 0 && isInputClosed)
	return IOStatus.EOF;
	}
	return IOStatus.normalize(n);
	} finally {
	readLock.unlock();
	}
	}

	/**
	* Marks the beginning of a write operation that might block.
	*
	* @throws ClosedChannelException if blocking and the channel is closed
	*/
	private void beginWrite(boolean blocking) throws ClosedChannelException {
	if (blocking) {
	// set hook for Thread.interrupt
	begin();

	synchronized (stateLock) {
	ensureOpen();
	if (isOutputClosed)
	throw new ClosedChannelException();
	// record thread so it can be signalled if needed
	writerThread = NativeThread.current();
	}
	}
	}

	/**
	* Marks the end of a write operation that may have blocked.
	*
	* @throws AsynchronousCloseException if the channel was closed due to this
	* thread being interrupted on a blocking write operation.
	*/
	private void endWrite(boolean blocking, boolean completed)
	throws AsynchronousCloseException
	{
	if (blocking) {
	synchronized (stateLock) {
	writerThread = 0;
	if (state == ST_CLOSING) {
	tryFinishClose();
	}
	}
	// remove hook for Thread.interrupt
	end(completed);
	}
	}

	@Override
	public int write(ByteBuffer buf) throws IOException {
	Objects.requireNonNull(buf);
	writeLock.lock();
	try {
	ensureOpenAndConnected();
	boolean blocking = isBlocking();
	int n = 0;
	try {
	beginWrite(blocking);
	n = IOUtil.write(fd, buf, -1, nd);
	if (blocking) {
	while (IOStatus.okayToRetry(n) && isOpen()) {
	park(Net.POLLOUT);
	n = IOUtil.write(fd, buf, -1, nd);
	}
	}
	} finally {
	endWrite(blocking, n > 0);
	if (n <= 0 && isOutputClosed)
	throw new AsynchronousCloseException();
	}
	return IOStatus.normalize(n);
	} finally {
	writeLock.unlock();
	}
	}

	@Override
	public long write(ByteBuffer[] srcs, int offset, int length)
	throws IOException
	{
	Objects.checkFromIndexSize(offset, length, srcs.length);

	writeLock.lock();
	try {
	ensureOpenAndConnected();
	boolean blocking = isBlocking();
	long n = 0;
	try {
	beginWrite(blocking);
	n = IOUtil.write(fd, srcs, offset, length, nd);
	if (blocking) {
	while (IOStatus.okayToRetry(n) && isOpen()) {
	park(Net.POLLOUT);
	n = IOUtil.write(fd, srcs, offset, length, nd);
	}
	}
	} finally {
	endWrite(blocking, n > 0);
	if (n <= 0 && isOutputClosed)
	throw new AsynchronousCloseException();
	}
	return IOStatus.normalize(n);
	} finally {
	writeLock.unlock();
	}
	}

	/**
	* Writes a byte of out of band data.
	*/
	int sendOutOfBandData(byte b) throws IOException {
	writeLock.lock();
	try {
	ensureOpenAndConnected();
	boolean blocking = isBlocking();
	int n = 0;
	try {
	beginWrite(blocking);
	if (blocking) {
	do {
	n = Net.sendOOB(fd, b);
	} while (n == IOStatus.INTERRUPTED && isOpen());
	} else {
	n = Net.sendOOB(fd, b);
	}
	} finally {
	endWrite(blocking, n > 0);
	if (n <= 0 && isOutputClosed)
	throw new AsynchronousCloseException();
	}
	return IOStatus.normalize(n);
	} finally {
	writeLock.unlock();
	}
	}

	@Override
	protected void implConfigureBlocking(boolean block) throws IOException {
	readLock.lock();
	try {
	writeLock.lock();
	try {
	lockedConfigureBlocking(block);
	} finally {
	writeLock.unlock();
	}
	} finally {
	readLock.unlock();
	}
	}

	/**
	* Adjusts the blocking mode. readLock or writeLock must already be held.
	*/
	private void lockedConfigureBlocking(boolean block) throws IOException {
	assert readLock.isHeldByCurrentThread() \|\| writeLock.isHeldByCurrentThread();
	synchronized (stateLock) {
	ensureOpen();
	IOUtil.configureBlocking(fd, block);
	}
	}

	/**
	* Adjusts the blocking mode if the channel is open. readLock or writeLock
	* must already be held.
	*
	* @return {@code true} if the blocking mode was adjusted, {@code false} if
	* the blocking mode was not adjusted because the channel is closed
	*/
	private boolean tryLockedConfigureBlocking(boolean block) throws IOException {
	assert readLock.isHeldByCurrentThread() \|\| writeLock.isHeldByCurrentThread();
	synchronized (stateLock) {
	if (isOpen()) {
	IOUtil.configureBlocking(fd, block);
	return true;
	} else {
	return false;
	}
	}
	}

	/**
	* Returns the local address, or null if not bound
	*/
	SocketAddress localAddress() {
	synchronized (stateLock) {
	return localAddress;
	}
	}

	/**
	* Returns the remote address, or null if not connected
	*/
	SocketAddress remoteAddress() {
	synchronized (stateLock) {
	return remoteAddress;
	}
	}

	@Override
	public SocketChannel bind(SocketAddress local) throws IOException {
	readLock.lock();
	try {
	writeLock.lock();
	try {
	synchronized (stateLock) {
	ensureOpen();
	if (state == ST_CONNECTIONPENDING)
	throw new ConnectionPendingException();
	if (localAddress != null)
	throw new AlreadyBoundException();
	if (isUnixSocket()) {
	localAddress = unixBind(local);
	} else {
	localAddress = netBind(local);
	}
	}
	} finally {
	writeLock.unlock();
	}
	} finally {
	readLock.unlock();
	}
	return this;
	}

	private SocketAddress unixBind(SocketAddress local) throws IOException {
	UnixDomainSockets.checkPermission();
	if (local == null) {
	return UnixDomainSockets.UNNAMED;
	} else {
	Path path = UnixDomainSockets.checkAddress(local).getPath();
	if (path.toString().isEmpty()) {
	return UnixDomainSockets.UNNAMED;
	} else {
	// bind to non-empty path
	UnixDomainSockets.bind(fd, path);
	return UnixDomainSockets.localAddress(fd);
	}
	}
	}

	private SocketAddress netBind(SocketAddress local) throws IOException {
	InetSocketAddress isa;
	if (local == null) {
	isa = new InetSocketAddress(Net.anyLocalAddress(family), 0);
	} else {
	isa = Net.checkAddress(local, family);
	}
	@SuppressWarnings("removal")
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	sm.checkListen(isa.getPort());
	}
	NetHooks.beforeTcpBind(fd, isa.getAddress(), isa.getPort());
	Net.bind(family, fd, isa.getAddress(), isa.getPort());
	return Net.localAddress(fd);
	}

	@Override
	public boolean isConnected() {
	return (state == ST_CONNECTED);
	}

	@Override
	public boolean isConnectionPending() {
	return (state == ST_CONNECTIONPENDING);
	}

	/**
	* Marks the beginning of a connect operation that might block.
	* @param blocking true if configured blocking
	* @param isa the remote address
	* @throws ClosedChannelException if the channel is closed
	* @throws AlreadyConnectedException if already connected
	* @throws ConnectionPendingException is a connection is pending
	* @throws IOException if the pre-connect hook fails
	*/
	private void beginConnect(boolean blocking, SocketAddress sa)
	throws IOException
	{
	if (blocking) {
	// set hook for Thread.interrupt
	begin();
	}
	synchronized (stateLock) {
	ensureOpen();
	int state = this.state;
	if (state == ST_CONNECTED)
	throw new AlreadyConnectedException();
	if (state == ST_CONNECTIONPENDING)
	throw new ConnectionPendingException();
	assert state == ST_UNCONNECTED;
	this.state = ST_CONNECTIONPENDING;

	if (isNetSocket() && (localAddress == null)) {
	InetSocketAddress isa = (InetSocketAddress) sa;
	NetHooks.beforeTcpConnect(fd, isa.getAddress(), isa.getPort());
	}
	remoteAddress = sa;

	if (blocking) {
	// record thread so it can be signalled if needed
	readerThread = NativeThread.current();
	}
	}
	}

	/**
	* Marks the end of a connect operation that may have blocked.
	*
	* @throws AsynchronousCloseException if the channel was closed due to this
	* thread being interrupted on a blocking connect operation.
	* @throws IOException if completed and unable to obtain the local address
	*/
	private void endConnect(boolean blocking, boolean completed)
	throws IOException
	{
	endRead(blocking, completed);

	if (completed) {
	synchronized (stateLock) {
	if (state == ST_CONNECTIONPENDING) {
	if (isUnixSocket()) {
	localAddress = UnixDomainSockets.localAddress(fd);
	} else {
	localAddress = Net.localAddress(fd);
	}
	state = ST_CONNECTED;
	}
	}
	}
	}

	/**
	* Checks the remote address to which this channel is to be connected.
	*/
	private SocketAddress checkRemote(SocketAddress sa) {
	if (isUnixSocket()) {
	UnixDomainSockets.checkPermission();
	return UnixDomainSockets.checkAddress(sa);
	} else {
	InetSocketAddress isa = Net.checkAddress(sa, family);
	@SuppressWarnings("removal")
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	sm.checkConnect(isa.getAddress().getHostAddress(), isa.getPort());
	}
	InetAddress address = isa.getAddress();
	if (address.isAnyLocalAddress()) {
	int port = isa.getPort();
	if (address instanceof Inet4Address) {
	return new InetSocketAddress(Net.inet4LoopbackAddress(), port);
	} else {
	assert family == INET6;
	return new InetSocketAddress(Net.inet6LoopbackAddress(), port);
	}
	} else {
	return isa;
	}
	}
	}

	@Override
	public boolean connect(SocketAddress remote) throws IOException {
	SocketAddress sa = checkRemote(remote);
	try {
	readLock.lock();
	try {
	writeLock.lock();
	try {
	boolean blocking = isBlocking();
	boolean connected = false;
	try {
	beginConnect(blocking, sa);
	int n;
	if (isUnixSocket()) {
	n = UnixDomainSockets.connect(fd, sa);
	} else {
	n = Net.connect(family, fd, sa);
	}
	if (n > 0) {
	connected = true;
	} else if (blocking) {
	assert IOStatus.okayToRetry(n);
	boolean polled = false;
	while (!polled && isOpen()) {
	park(Net.POLLOUT);
	polled = Net.pollConnectNow(fd);
	}
	connected = polled && isOpen();
	}
	} finally {
	endConnect(blocking, connected);
	}
	return connected;
	} finally {
	writeLock.unlock();
	}
	} finally {
	readLock.unlock();
	}
	} catch (IOException ioe) {
	// connect failed, close the channel
	close();
	throw SocketExceptions.of(ioe, sa);
	}
	}

	/**
	* Marks the beginning of a finishConnect operation that might block.
	*
	* @throws ClosedChannelException if the channel is closed
	* @throws NoConnectionPendingException if no connection is pending
	*/
	private void beginFinishConnect(boolean blocking) throws ClosedChannelException {
	if (blocking) {
	// set hook for Thread.interrupt
	begin();
	}
	synchronized (stateLock) {
	ensureOpen();
	if (state != ST_CONNECTIONPENDING)
	throw new NoConnectionPendingException();
	if (blocking) {
	// record thread so it can be signalled if needed
	readerThread = NativeThread.current();
	}
	}
	}

	/**
	* Marks the end of a finishConnect operation that may have blocked.
	*
	* @throws AsynchronousCloseException if the channel was closed due to this
	* thread being interrupted on a blocking connect operation.
	* @throws IOException if completed and unable to obtain the local address
	*/
	private void endFinishConnect(boolean blocking, boolean completed)
	throws IOException
	{
	endRead(blocking, completed);

	if (completed) {
	synchronized (stateLock) {
	if (state == ST_CONNECTIONPENDING) {
	if (isUnixSocket()) {
	localAddress = UnixDomainSockets.localAddress(fd);
	} else {
	localAddress = Net.localAddress(fd);
	}
	state = ST_CONNECTED;
	}
	}
	}
	}

	@Override
	public boolean finishConnect() throws IOException {
	try {
	readLock.lock();
	try {
	writeLock.lock();
	try {
	// no-op if already connected
	if (isConnected())
	return true;

	boolean blocking = isBlocking();
	boolean connected = false;
	try {
	beginFinishConnect(blocking);
	boolean polled = Net.pollConnectNow(fd);
	if (blocking) {
	while (!polled && isOpen()) {
	park(Net.POLLOUT);
	polled = Net.pollConnectNow(fd);
	}
	}
	connected = polled && isOpen();
	} finally {
	endFinishConnect(blocking, connected);
	}
	assert (blocking && connected) ^ !blocking;
	return connected;
	} finally {
	writeLock.unlock();
	}
	} finally {
	readLock.unlock();
	}
	} catch (IOException ioe) {
	// connect failed, close the channel
	close();
	throw SocketExceptions.of(ioe, remoteAddress);
	}
	}

	/**
	* Closes the socket if there are no I/O operations in progress and the
	* channel is not registered with a Selector.
	*/
	private boolean tryClose() throws IOException {
	assert Thread.holdsLock(stateLock) && state == ST_CLOSING;
	if ((readerThread == 0) && (writerThread == 0) && !isRegistered()) {
	state = ST_CLOSED;
	nd.close(fd);
	return true;
	} else {
	return false;
	}
	}

	/**
	* Invokes tryClose to attempt to close the socket.
	*
	* This method is used for deferred closing by I/O and Selector operations.
	*/
	private void tryFinishClose() {
	try {
	tryClose();
	} catch (IOException ignore) { }
	}

	/**
	* Closes this channel when configured in blocking mode.
	*
	* If there is an I/O operation in progress then the socket is pre-closed
	* and the I/O threads signalled, in which case the final close is deferred
	* until all I/O operations complete.
	*
	* Note that a channel configured blocking may be registered with a Selector
	* This arises when a key is canceled and the channel configured to blocking
	* mode before the key is flushed from the Selector.
	*/
	private void implCloseBlockingMode() throws IOException {
	synchronized (stateLock) {
	assert state < ST_CLOSING;
	state = ST_CLOSING;
	if (!tryClose()) {
	long reader = readerThread;
	long writer = writerThread;
	if (reader != 0 \|\| writer != 0) {
	nd.preClose(fd);
	if (reader != 0)
	NativeThread.signal(reader);
	if (writer != 0)
	NativeThread.signal(writer);
	}
	}
	}
	}

	/**
	* Closes this channel when configured in non-blocking mode.
	*
	* If the channel is registered with a Selector then the close is deferred
	* until the channel is flushed from all Selectors.
	*
	* If the socket is connected and the channel is registered with a Selector
	* then the socket is shutdown for writing so that the peer reads EOF. In
	* addition, if SO_LINGER is set to a non-zero value then it is disabled so
	* that the deferred close does not wait.
	*/
	private void implCloseNonBlockingMode() throws IOException {
	boolean connected;
	synchronized (stateLock) {
	assert state < ST_CLOSING;
	connected = (state == ST_CONNECTED);
	state = ST_CLOSING;
	}

	// wait for any read/write operations to complete
	readLock.lock();
	readLock.unlock();
	writeLock.lock();
	writeLock.unlock();

	// if the socket cannot be closed because it's registered with a Selector
	// then shutdown the socket for writing.
	synchronized (stateLock) {
	if (state == ST_CLOSING && !tryClose() && connected && isRegistered()) {
	try {
	SocketOption<Integer> opt = StandardSocketOptions.SO_LINGER;
	int interval = (int) Net.getSocketOption(fd, Net.UNSPEC, opt);
	if (interval != 0) {
	if (interval > 0) {
	// disable SO_LINGER
	Net.setSocketOption(fd, Net.UNSPEC, opt, -1);
	}
	Net.shutdown(fd, Net.SHUT_WR);
	}
	} catch (IOException ignore) { }
	}
	}
	}

	/**
	* Invoked by implCloseChannel to close the channel.
	*/
	@Override
	protected void implCloseSelectableChannel() throws IOException {
	assert !isOpen();
	if (isBlocking()) {
	implCloseBlockingMode();
	} else {
	implCloseNonBlockingMode();
	}
	}

	@Override
	public void kill() {
	synchronized (stateLock) {
	if (state == ST_CLOSING) {
	tryFinishClose();
	}
	}
	}

	@Override
	public SocketChannel shutdownInput() throws IOException {
	synchronized (stateLock) {
	ensureOpen();
	if (!isConnected())
	throw new NotYetConnectedException();
	if (!isInputClosed) {
	Net.shutdown(fd, Net.SHUT_RD);
	long thread = readerThread;
	if (thread != 0)
	NativeThread.signal(thread);
	isInputClosed = true;
	}
	return this;
	}
	}

	@Override
	public SocketChannel shutdownOutput() throws IOException {
	synchronized (stateLock) {
	ensureOpen();
	if (!isConnected())
	throw new NotYetConnectedException();
	if (!isOutputClosed) {
	Net.shutdown(fd, Net.SHUT_WR);
	long thread = writerThread;
	if (thread != 0)
	NativeThread.signal(thread);
	isOutputClosed = true;
	}
	return this;
	}
	}

	boolean isInputOpen() {
	return !isInputClosed;
	}

	boolean isOutputOpen() {
	return !isOutputClosed;
	}

	/**
	* Waits for a connection attempt to finish with a timeout
	* @throws SocketTimeoutException if the connect timeout elapses
	*/
	private boolean finishTimedConnect(long nanos) throws IOException {
	long startNanos = System.nanoTime();
	boolean polled = Net.pollConnectNow(fd);
	while (!polled && isOpen()) {
	long remainingNanos = nanos - (System.nanoTime() - startNanos);
	if (remainingNanos <= 0) {
	throw new SocketTimeoutException("Connect timed out");
	}
	park(Net.POLLOUT, remainingNanos);
	polled = Net.pollConnectNow(fd);
	}
	return polled && isOpen();
	}

	/**
	* Attempts to establish a connection to the given socket address with a
	* timeout. Closes the socket if connection cannot be established.
	*
	* @apiNote This method is for use by the socket adaptor.
	*
	* @throws IllegalBlockingModeException if the channel is non-blocking
	* @throws SocketTimeoutException if the read timeout elapses
	*/
	void blockingConnect(SocketAddress remote, long nanos) throws IOException {
	SocketAddress sa = checkRemote(remote);
	try {
	readLock.lock();
	try {
	writeLock.lock();
	try {
	if (!isBlocking())
	throw new IllegalBlockingModeException();
	boolean connected = false;
	try {
	beginConnect(true, sa);
	// change socket to non-blocking
	lockedConfigureBlocking(false);
	try {
	int n;
	if (isUnixSocket()) {
	n = UnixDomainSockets.connect(fd, sa);
	} else {
	n = Net.connect(family, fd, sa);
	}
	connected = (n > 0) ? true : finishTimedConnect(nanos);
	} finally {
	// restore socket to blocking mode (if channel is open)
	tryLockedConfigureBlocking(true);
	}
	} finally {
	endConnect(true, connected);
	}
	} finally {
	writeLock.unlock();
	}
	} finally {
	readLock.unlock();
	}
	} catch (IOException ioe) {
	// connect failed, close the channel
	close();
	throw SocketExceptions.of(ioe, sa);
	}
	}

	/**
	* Attempts to read bytes from the socket into the given byte array.
	*/
	private int tryRead(byte[] b, int off, int len) throws IOException {
	ByteBuffer dst = Util.getTemporaryDirectBuffer(len);
	assert dst.position() == 0;
	try {
	int n = nd.read(fd, ((DirectBuffer)dst).address(), len);
	if (n > 0) {
	dst.get(b, off, n);
	}
	return n;
	} finally{
	Util.offerFirstTemporaryDirectBuffer(dst);
	}
	}

	/**
	* Reads bytes from the socket into the given byte array with a timeout.
	* @throws SocketTimeoutException if the read timeout elapses
	*/
	private int timedRead(byte[] b, int off, int len, long nanos) throws IOException {
	long startNanos = System.nanoTime();
	int n = tryRead(b, off, len);
	while (n == IOStatus.UNAVAILABLE && isOpen()) {
	long remainingNanos = nanos - (System.nanoTime() - startNanos);
	if (remainingNanos <= 0) {
	throw new SocketTimeoutException("Read timed out");
	}
	park(Net.POLLIN, remainingNanos);
	n = tryRead(b, off, len);
	}
	return n;
	}

	/**
	* Reads bytes from the socket into the given byte array.
	*
	* @apiNote This method is for use by the socket adaptor.
	*
	* @throws IllegalBlockingModeException if the channel is non-blocking
	* @throws SocketTimeoutException if the read timeout elapses
	*/
	int blockingRead(byte[] b, int off, int len, long nanos) throws IOException {
	Objects.checkFromIndexSize(off, len, b.length);
	if (len == 0) {
	// nothing to do
	return 0;
	}

	readLock.lock();
	try {
	ensureOpenAndConnected();

	// check that channel is configured blocking
	if (!isBlocking())
	throw new IllegalBlockingModeException();

	int n = 0;
	try {
	beginRead(true);

	// check if connection has been reset
	if (connectionReset)
	throwConnectionReset();

	// check if input is shutdown
	if (isInputClosed)
	return IOStatus.EOF;

	if (nanos > 0) {
	// change socket to non-blocking
	lockedConfigureBlocking(false);
	try {
	n = timedRead(b, off, len, nanos);
	} finally {
	// restore socket to blocking mode (if channel is open)
	tryLockedConfigureBlocking(true);
	}
	} else {
	// read, no timeout
	n = tryRead(b, off, len);
	while (IOStatus.okayToRetry(n) && isOpen()) {
	park(Net.POLLIN);
	n = tryRead(b, off, len);
	}
	}
	} catch (ConnectionResetException e) {
	connectionReset = true;
	throwConnectionReset();
	} finally {
	endRead(true, n > 0);
	if (n <= 0 && isInputClosed)
	return IOStatus.EOF;
	}
	assert n > 0 \|\| n == -1;
	return n;
	} finally {
	readLock.unlock();
	}
	}

	/**
	* Attempts to write a sequence of bytes to the socket from the given
	* byte array.
	*/
	private int tryWrite(byte[] b, int off, int len) throws IOException {
	ByteBuffer src = Util.getTemporaryDirectBuffer(len);
	assert src.position() == 0;
	try {
	src.put(b, off, len);
	return nd.write(fd, ((DirectBuffer)src).address(), len);
	} finally {
	Util.offerFirstTemporaryDirectBuffer(src);
	}
	}

	/**
	* Writes a sequence of bytes to the socket from the given byte array.
	*
	* @apiNote This method is for use by the socket adaptor.
	*/
	void blockingWriteFully(byte[] b, int off, int len) throws IOException {
	Objects.checkFromIndexSize(off, len, b.length);
	if (len == 0) {
	// nothing to do
	return;
	}

	writeLock.lock();
	try {
	ensureOpenAndConnected();

	// check that channel is configured blocking
	if (!isBlocking())
	throw new IllegalBlockingModeException();

	// loop until all bytes have been written
	int pos = off;
	int end = off + len;
	try {
	beginWrite(true);
	while (pos < end && isOpen()) {
	int size = end - pos;
	int n = tryWrite(b, pos, size);
	while (IOStatus.okayToRetry(n) && isOpen()) {
	park(Net.POLLOUT);
	n = tryWrite(b, pos, size);
	}
	if (n > 0) {
	pos += n;
	}
	}
	} finally {
	endWrite(true, pos >= end);
	}
	} finally {
	writeLock.unlock();
	}
	}

	/**
	* Return the number of bytes in the socket input buffer.
	*/
	int available() throws IOException {
	synchronized (stateLock) {
	ensureOpenAndConnected();
	if (isInputClosed) {
	return 0;
	} else {
	return Net.available(fd);
	}
	}
	}

	/**
	* Translates native poll revent ops into a ready operation ops
	*/
	public boolean translateReadyOps(int ops, int initialOps, SelectionKeyImpl ski) {
	int intOps = ski.nioInterestOps();
	int oldOps = ski.nioReadyOps();
	int newOps = initialOps;

	if ((ops & Net.POLLNVAL) != 0) {
	// This should only happen if this channel is pre-closed while a
	// selection operation is in progress
	// ## Throw an error if this channel has not been pre-closed
	return false;
	}

	if ((ops & (Net.POLLERR \| Net.POLLHUP)) != 0) {
	newOps = intOps;
	ski.nioReadyOps(newOps);
	return (newOps & ~oldOps) != 0;
	}

	boolean connected = isConnected();
	if (((ops & Net.POLLIN) != 0) &&
	((intOps & SelectionKey.OP_READ) != 0) && connected)
	newOps \|= SelectionKey.OP_READ;

	if (((ops & Net.POLLCONN) != 0) &&
	((intOps & SelectionKey.OP_CONNECT) != 0) && isConnectionPending())
	newOps \|= SelectionKey.OP_CONNECT;

	if (((ops & Net.POLLOUT) != 0) &&
	((intOps & SelectionKey.OP_WRITE) != 0) && connected)
	newOps \|= SelectionKey.OP_WRITE;

	ski.nioReadyOps(newOps);
	return (newOps & ~oldOps) != 0;
	}

	public boolean translateAndUpdateReadyOps(int ops, SelectionKeyImpl ski) {
	return translateReadyOps(ops, ski.nioReadyOps(), ski);
	}

	public boolean translateAndSetReadyOps(int ops, SelectionKeyImpl ski) {
	return translateReadyOps(ops, 0, ski);
	}

	/**
	* Translates an interest operation set into a native poll event set
	*/
	public int translateInterestOps(int ops) {
	int newOps = 0;
	if ((ops & SelectionKey.OP_READ) != 0)
	newOps \|= Net.POLLIN;
	if ((ops & SelectionKey.OP_WRITE) != 0)
	newOps \|= Net.POLLOUT;
	if ((ops & SelectionKey.OP_CONNECT) != 0)
	newOps \|= Net.POLLCONN;
	return newOps;
	}

	public FileDescriptor getFD() {
	return fd;
	}

	public int getFDVal() {
	return fdVal;
	}

	@Override
	public String toString() {
	StringBuilder sb = new StringBuilder();
	sb.append(this.getClass().getSuperclass().getName());
	sb.append('[');
	if (!isOpen())
	sb.append("closed");
	else {
	synchronized (stateLock) {
	switch (state) {
	case ST_UNCONNECTED:
	sb.append("unconnected");
	break;
	case ST_CONNECTIONPENDING:
	sb.append("connection-pending");
	break;
	case ST_CONNECTED:
	sb.append("connected");
	if (isInputClosed)
	sb.append(" ishut");
	if (isOutputClosed)
	sb.append(" oshut");
	break;
	}
	SocketAddress addr = localAddress();
	if (addr != null) {
	sb.append(" local=");
	if (isUnixSocket()) {
	sb.append(UnixDomainSockets.getRevealedLocalAddressAsString(addr));
	} else {
	sb.append(Net.getRevealedLocalAddressAsString(addr));
	}
	}
	if (remoteAddress() != null) {
	sb.append(" remote=");
	sb.append(remoteAddress().toString());
	}
	}
	}
	sb.append(']');
	return sb.toString();
	}
	}

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