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	/*
	* Copyright (c) 2000, 2018, 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.InetSocketAddress;
	import java.net.ProtocolFamily;
	import java.net.ServerSocket;
	import java.net.SocketAddress;
	import java.net.SocketOption;
	import java.net.StandardProtocolFamily;
	import java.net.StandardSocketOptions;
	import java.nio.channels.AlreadyBoundException;
	import java.nio.channels.AsynchronousCloseException;
	import java.nio.channels.ClosedChannelException;
	import java.nio.channels.NotYetBoundException;
	import java.nio.channels.SelectionKey;
	import java.nio.channels.ServerSocketChannel;
	import java.nio.channels.SocketChannel;
	import java.nio.channels.spi.SelectorProvider;
	import java.util.Collections;
	import java.util.HashSet;
	import java.util.Objects;
	import java.util.Set;
	import java.util.concurrent.locks.ReentrantLock;

	import sun.net.NetHooks;
	import sun.net.ext.ExtendedSocketOptions;
	import static sun.net.ext.ExtendedSocketOptions.SOCK_STREAM;

	/**
	* An implementation of ServerSocketChannels
	*/

	class ServerSocketChannelImpl
	extends ServerSocketChannel
	implements SelChImpl
	{
	// Used to make native close and configure calls
	private static NativeDispatcher nd;

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

	// Lock held by thread currently blocked on this channel
	private final ReentrantLock acceptLock = 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();

	// -- The following fields are protected by stateLock

	// Channel state, increases monotonically
	private static final int ST_INUSE = 0;
	private static final int ST_CLOSING = 1;
	private static final int ST_KILLPENDING = 2;
	private static final int ST_KILLED = 3;
	private int state;

	// ID of native thread currently blocked in this channel, for signalling
	private long thread;

	// Binding
	private InetSocketAddress localAddress; // null => unbound

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

	// Our socket adaptor, if any
	private ServerSocket socket;

	// -- End of fields protected by stateLock


	ServerSocketChannelImpl(SelectorProvider sp) throws IOException {
	super(sp);
	this.fd = Net.serverSocket(true);
	this.fdVal = IOUtil.fdVal(fd);
	}

	ServerSocketChannelImpl(SelectorProvider sp, FileDescriptor fd, boolean bound)
	throws IOException
	{
	super(sp);
	this.fd = fd;
	this.fdVal = IOUtil.fdVal(fd);
	if (bound) {
	synchronized (stateLock) {
	localAddress = Net.localAddress(fd);
	}
	}
	}

	// @throws ClosedChannelException if channel is closed
	private void ensureOpen() throws ClosedChannelException {
	if (!isOpen())
	throw new ClosedChannelException();
	}

	@Override
	public ServerSocket socket() {
	synchronized (stateLock) {
	if (socket == null)
	socket = ServerSocketAdaptor.create(this);
	return socket;
	}
	}

	@Override
	public SocketAddress getLocalAddress() throws IOException {
	synchronized (stateLock) {
	ensureOpen();
	return (localAddress == null)
	? null
	: Net.getRevealedLocalAddress(localAddress);
	}
	}

	@Override
	public <T> ServerSocketChannel setOption(SocketOption<T> name, T value)
	throws IOException
	{
	Objects.requireNonNull(name);
	if (!supportedOptions().contains(name))
	throw new UnsupportedOperationException("'" + name + "' not supported");
	synchronized (stateLock) {
	ensureOpen();

	if (name == StandardSocketOptions.IP_TOS) {
	ProtocolFamily family = Net.isIPv6Available() ?
	StandardProtocolFamily.INET6 : StandardProtocolFamily.INET;
	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;
	} else {
	// no options that require special handling
	Net.setSocketOption(fd, Net.UNSPEC, 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 (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, Net.UNSPEC, name);
	}
	}

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

	private static Set<SocketOption<?>> defaultOptions() {
	HashSet<SocketOption<?>> set = new HashSet<>();
	set.add(StandardSocketOptions.SO_RCVBUF);
	set.add(StandardSocketOptions.SO_REUSEADDR);
	if (Net.isReusePortAvailable()) {
	set.add(StandardSocketOptions.SO_REUSEPORT);
	}
	set.add(StandardSocketOptions.IP_TOS);
	set.addAll(ExtendedSocketOptions.options(SOCK_STREAM));
	return Collections.unmodifiableSet(set);
	}
	}

	@Override
	public final Set<SocketOption<?>> supportedOptions() {
	return DefaultOptionsHolder.defaultOptions;
	}

	@Override
	public ServerSocketChannel bind(SocketAddress local, int backlog) throws IOException {
	synchronized (stateLock) {
	ensureOpen();
	if (localAddress != null)
	throw new AlreadyBoundException();
	InetSocketAddress isa = (local == null)
	? new InetSocketAddress(0)
	: Net.checkAddress(local);
	SecurityManager sm = System.getSecurityManager();
	if (sm != null)
	sm.checkListen(isa.getPort());
	NetHooks.beforeTcpBind(fd, isa.getAddress(), isa.getPort());
	Net.bind(fd, isa.getAddress(), isa.getPort());
	Net.listen(fd, backlog < 1 ? 50 : backlog);
	localAddress = Net.localAddress(fd);
	}
	return this;
	}

	/**
	* Marks the beginning of an I/O operation that might block.
	*
	* @throws ClosedChannelException if the channel is closed
	* @throws NotYetBoundException if the channel's socket has not been bound yet
	*/
	private void begin(boolean blocking) throws ClosedChannelException {
	if (blocking)
	begin(); // set blocker to close channel if interrupted
	synchronized (stateLock) {
	ensureOpen();
	if (localAddress == null)
	throw new NotYetBoundException();
	if (blocking)
	thread = NativeThread.current();
	}
	}

	/**
	* Marks the end of an I/O operation that may have blocked.
	*
	* @throws AsynchronousCloseException if the channel was closed due to this
	* thread being interrupted on a blocking I/O operation.
	*/
	private void end(boolean blocking, boolean completed)
	throws AsynchronousCloseException
	{
	if (blocking) {
	synchronized (stateLock) {
	thread = 0;
	// notify any thread waiting in implCloseSelectableChannel
	if (state == ST_CLOSING) {
	stateLock.notifyAll();
	}
	}
	end(completed);
	}
	}

	@Override
	public SocketChannel accept() throws IOException {
	acceptLock.lock();
	try {
	int n = 0;
	FileDescriptor newfd = new FileDescriptor();
	InetSocketAddress[] isaa = new InetSocketAddress[1];

	boolean blocking = isBlocking();
	try {
	begin(blocking);
	do {
	n = accept(this.fd, newfd, isaa);
	} while (n == IOStatus.INTERRUPTED && isOpen());
	} finally {
	end(blocking, n > 0);
	assert IOStatus.check(n);
	}

	if (n < 1)
	return null;

	// newly accepted socket is initially in blocking mode
	IOUtil.configureBlocking(newfd, true);

	InetSocketAddress isa = isaa[0];
	SocketChannel sc = new SocketChannelImpl(provider(), newfd, isa);

	// check permitted to accept connections from the remote address
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	try {
	sm.checkAccept(isa.getAddress().getHostAddress(), isa.getPort());
	} catch (SecurityException x) {
	sc.close();
	throw x;
	}
	}
	return sc;

	} finally {
	acceptLock.unlock();
	}
	}

	@Override
	protected void implConfigureBlocking(boolean block) throws IOException {
	acceptLock.lock();
	try {
	synchronized (stateLock) {
	ensureOpen();
	IOUtil.configureBlocking(fd, block);
	}
	} finally {
	acceptLock.unlock();
	}
	}

	/**
	* Invoked by implCloseChannel to close the channel.
	*
	* This method waits for outstanding I/O operations to complete. When in
	* blocking mode, the socket is pre-closed and the threads in blocking I/O
	* operations are signalled to ensure that the outstanding I/O operations
	* complete quickly.
	*
	* The socket is closed by this method when it is not registered with a
	* Selector. 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.
	*/
	@Override
	protected void implCloseSelectableChannel() throws IOException {
	assert !isOpen();

	boolean interrupted = false;
	boolean blocking;

	// set state to ST_CLOSING
	synchronized (stateLock) {
	assert state < ST_CLOSING;
	state = ST_CLOSING;
	blocking = isBlocking();
	}

	// wait for any outstanding accept to complete
	if (blocking) {
	synchronized (stateLock) {
	assert state == ST_CLOSING;
	long th = thread;
	if (th != 0) {
	nd.preClose(fd);
	NativeThread.signal(th);

	// wait for accept operation to end
	while (thread != 0) {
	try {
	stateLock.wait();
	} catch (InterruptedException e) {
	interrupted = true;
	}
	}
	}
	}
	} else {
	// non-blocking mode: wait for accept to complete
	acceptLock.lock();
	acceptLock.unlock();
	}

	// set state to ST_KILLPENDING
	synchronized (stateLock) {
	assert state == ST_CLOSING;
	state = ST_KILLPENDING;
	}

	// close socket if not registered with Selector
	if (!isRegistered())
	kill();

	// restore interrupt status
	if (interrupted)
	Thread.currentThread().interrupt();
	}

	@Override
	public void kill() throws IOException {
	synchronized (stateLock) {
	if (state == ST_KILLPENDING) {
	state = ST_KILLED;
	nd.close(fd);
	}
	}
	}

	/**
	* Returns true if channel's socket is bound
	*/
	boolean isBound() {
	synchronized (stateLock) {
	return localAddress != null;
	}
	}

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

	/**
	* Poll this channel's socket for a new connection up to the given timeout.
	* @return {@code true} if there is a connection to accept
	*/
	boolean pollAccept(long timeout) throws IOException {
	assert Thread.holdsLock(blockingLock()) && isBlocking();
	acceptLock.lock();
	try {
	boolean polled = false;
	try {
	begin(true);
	int events = Net.poll(fd, Net.POLLIN, timeout);
	polled = (events != 0);
	} finally {
	end(true, polled);
	}
	return polled;
	} finally {
	acceptLock.unlock();
	}
	}

	/**
	* Translates native poll revent set into a ready operation set
	*/
	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;
	}

	if (((ops & Net.POLLIN) != 0) &&
	((intOps & SelectionKey.OP_ACCEPT) != 0))
	newOps \|= SelectionKey.OP_ACCEPT;

	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_ACCEPT) != 0)
	newOps \|= Net.POLLIN;
	return newOps;
	}

	public FileDescriptor getFD() {
	return fd;
	}

	public int getFDVal() {
	return fdVal;
	}

	public String toString() {
	StringBuilder sb = new StringBuilder();
	sb.append(this.getClass().getName());
	sb.append('[');
	if (!isOpen()) {
	sb.append("closed");
	} else {
	synchronized (stateLock) {
	InetSocketAddress addr = localAddress;
	if (addr == null) {
	sb.append("unbound");
	} else {
	sb.append(Net.getRevealedLocalAddressAsString(addr));
	}
	}
	}
	sb.append(']');
	return sb.toString();
	}

	/**
	* Accept a connection on a socket.
	*
	* @implNote Wrap native call to allow instrumentation.
	*/
	private int accept(FileDescriptor ssfd,
	FileDescriptor newfd,
	InetSocketAddress[] isaa)
	throws IOException
	{
	return accept0(ssfd, newfd, isaa);
	}

	// -- Native methods --

	// Accepts a new connection, setting the given file descriptor to refer to
	// the new socket and setting isaa[0] to the socket's remote address.
	// Returns 1 on success, or IOStatus.UNAVAILABLE (if non-blocking and no
	// connections are pending) or IOStatus.INTERRUPTED.
	//
	private native int accept0(FileDescriptor ssfd,
	FileDescriptor newfd,
	InetSocketAddress[] isaa)
	throws IOException;

	private static native void initIDs();

	static {
	IOUtil.load();
	initIDs();
	nd = new SocketDispatcher();
	}

	}

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