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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.nio.ByteBuffer;
	import java.util.Objects;
	import jdk.internal.access.JavaNioAccess;
	import jdk.internal.access.SharedSecrets;
	import jdk.internal.misc.ScopedMemoryAccess.Scope;

	/**
	* File-descriptor based I/O utilities that are shared by NIO classes.
	*/

	public class IOUtil {

	/**
	* Max number of iovec structures that readv/writev supports
	*/
	static final int IOV_MAX;

	private IOUtil() { } // No instantiation

	static int write(FileDescriptor fd, ByteBuffer src, long position,
	NativeDispatcher nd)
	throws IOException
	{
	return write(fd, src, position, false, false, -1, nd);
	}

	static int write(FileDescriptor fd, ByteBuffer src, long position,
	boolean async, NativeDispatcher nd)
	throws IOException
	{
	return write(fd, src, position, false, async, -1, nd);
	}

	static int write(FileDescriptor fd, ByteBuffer src, long position,
	boolean directIO, int alignment, NativeDispatcher nd)
	throws IOException
	{
	return write(fd, src, position, directIO, false, alignment, nd);
	}

	static int write(FileDescriptor fd, ByteBuffer src, long position,
	boolean directIO, boolean async, int alignment,
	NativeDispatcher nd)
	throws IOException
	{
	if (src instanceof DirectBuffer) {
	return writeFromNativeBuffer(fd, src, position, directIO, async, alignment, nd);
	}

	// Substitute a native buffer
	int pos = src.position();
	int lim = src.limit();
	assert (pos <= lim);
	int rem = (pos <= lim ? lim - pos : 0);
	ByteBuffer bb;
	if (directIO) {
	Util.checkRemainingBufferSizeAligned(rem, alignment);
	bb = Util.getTemporaryAlignedDirectBuffer(rem, alignment);
	} else {
	bb = Util.getTemporaryDirectBuffer(rem);
	}
	try {
	bb.put(src);
	bb.flip();
	// Do not update src until we see how many bytes were written
	src.position(pos);

	int n = writeFromNativeBuffer(fd, bb, position, directIO, async, alignment, nd);
	if (n > 0) {
	// now update src
	src.position(pos + n);
	}
	return n;
	} finally {
	Util.offerFirstTemporaryDirectBuffer(bb);
	}
	}

	private static int writeFromNativeBuffer(FileDescriptor fd, ByteBuffer bb,
	long position, boolean directIO,
	boolean async, int alignment,
	NativeDispatcher nd)
	throws IOException
	{
	int pos = bb.position();
	int lim = bb.limit();
	assert (pos <= lim);
	int rem = (pos <= lim ? lim - pos : 0);

	if (directIO) {
	Util.checkBufferPositionAligned(bb, pos, alignment);
	Util.checkRemainingBufferSizeAligned(rem, alignment);
	}

	int written = 0;
	if (rem == 0)
	return 0;
	var handle = acquireScope(bb, async);
	try {
	if (position != -1) {
	written = nd.pwrite(fd, bufferAddress(bb) + pos, rem, position);
	} else {
	written = nd.write(fd, bufferAddress(bb) + pos, rem);
	}
	} finally {
	releaseScope(handle);
	}
	if (written > 0)
	bb.position(pos + written);
	return written;
	}

	static long write(FileDescriptor fd, ByteBuffer[] bufs, boolean async,
	NativeDispatcher nd)
	throws IOException
	{
	return write(fd, bufs, 0, bufs.length, false, async, -1, nd);
	}

	static long write(FileDescriptor fd, ByteBuffer[] bufs, int offset, int length,
	NativeDispatcher nd)
	throws IOException
	{
	return write(fd, bufs, offset, length, false, false, -1, nd);
	}

	static long write(FileDescriptor fd, ByteBuffer[] bufs, int offset, int length,
	boolean direct, int alignment, NativeDispatcher nd)
	throws IOException
	{
	return write(fd, bufs, offset, length, direct, false, alignment, nd);
	}

	static long write(FileDescriptor fd, ByteBuffer[] bufs, int offset, int length,
	boolean directIO, boolean async,
	int alignment, NativeDispatcher nd)
	throws IOException
	{
	IOVecWrapper vec = IOVecWrapper.get(length);

	boolean completed = false;
	int iov_len = 0;
	Runnable handleReleasers = null;
	try {
	// Iterate over buffers to populate native iovec array.
	int count = offset + length;
	int i = offset;
	while (i < count && iov_len < IOV_MAX) {
	ByteBuffer buf = bufs[i];
	var h = acquireScope(buf, async);
	if (h != null) {
	handleReleasers = LinkedRunnable.of(Releaser.of(h), handleReleasers);
	}
	int pos = buf.position();
	int lim = buf.limit();
	assert (pos <= lim);
	int rem = (pos <= lim ? lim - pos : 0);
	if (directIO)
	Util.checkRemainingBufferSizeAligned(rem, alignment);

	if (rem > 0) {
	vec.setBuffer(iov_len, buf, pos, rem);

	// allocate shadow buffer to ensure I/O is done with direct buffer
	if (!(buf instanceof DirectBuffer)) {
	ByteBuffer shadow;
	if (directIO)
	shadow = Util.getTemporaryAlignedDirectBuffer(rem, alignment);
	else
	shadow = Util.getTemporaryDirectBuffer(rem);
	shadow.put(buf);
	shadow.flip();
	vec.setShadow(iov_len, shadow);
	buf.position(pos); // temporarily restore position in user buffer
	buf = shadow;
	pos = shadow.position();
	}

	vec.putBase(iov_len, bufferAddress(buf) + pos);
	vec.putLen(iov_len, rem);
	iov_len++;
	}
	i++;
	}
	if (iov_len == 0)
	return 0L;

	long bytesWritten = nd.writev(fd, vec.address, iov_len);

	// Notify the buffers how many bytes were taken
	long left = bytesWritten;
	for (int j=0; j<iov_len; j++) {
	if (left > 0) {
	ByteBuffer buf = vec.getBuffer(j);
	int pos = vec.getPosition(j);
	int rem = vec.getRemaining(j);
	int n = (left > rem) ? rem : (int)left;
	buf.position(pos + n);
	left -= n;
	}
	// return shadow buffers to buffer pool
	ByteBuffer shadow = vec.getShadow(j);
	if (shadow != null)
	Util.offerLastTemporaryDirectBuffer(shadow);
	vec.clearRefs(j);
	}

	completed = true;
	return bytesWritten;

	} finally {
	releaseScopes(handleReleasers);
	// if an error occurred then clear refs to buffers and return any shadow
	// buffers to cache
	if (!completed) {
	for (int j=0; j<iov_len; j++) {
	ByteBuffer shadow = vec.getShadow(j);
	if (shadow != null)
	Util.offerLastTemporaryDirectBuffer(shadow);
	vec.clearRefs(j);
	}
	}
	}
	}

	static int read(FileDescriptor fd, ByteBuffer dst, long position,
	NativeDispatcher nd)
	throws IOException
	{
	return read(fd, dst, position, false, false, -1, nd);
	}

	static int read(FileDescriptor fd, ByteBuffer dst, long position,
	boolean async, NativeDispatcher nd)
	throws IOException
	{
	return read(fd, dst, position, false, async, -1, nd);
	}

	static int read(FileDescriptor fd, ByteBuffer dst, long position,
	boolean directIO, int alignment, NativeDispatcher nd)
	throws IOException
	{
	return read(fd, dst, position, directIO, false, alignment, nd);
	}

	static int read(FileDescriptor fd, ByteBuffer dst, long position,
	boolean directIO, boolean async,
	int alignment, NativeDispatcher nd)
	throws IOException
	{
	if (dst.isReadOnly())
	throw new IllegalArgumentException("Read-only buffer");
	if (dst instanceof DirectBuffer)
	return readIntoNativeBuffer(fd, dst, position, directIO, async, alignment, nd);

	// Substitute a native buffer
	ByteBuffer bb;
	int rem = dst.remaining();
	if (directIO) {
	Util.checkRemainingBufferSizeAligned(rem, alignment);
	bb = Util.getTemporaryAlignedDirectBuffer(rem, alignment);
	} else {
	bb = Util.getTemporaryDirectBuffer(rem);
	}
	try {
	int n = readIntoNativeBuffer(fd, bb, position, directIO, async, alignment, nd);
	bb.flip();
	if (n > 0)
	dst.put(bb);
	return n;
	} finally {
	Util.offerFirstTemporaryDirectBuffer(bb);
	}
	}

	private static int readIntoNativeBuffer(FileDescriptor fd, ByteBuffer bb,
	long position, boolean directIO,
	boolean async, int alignment,
	NativeDispatcher nd)
	throws IOException
	{
	int pos = bb.position();
	int lim = bb.limit();
	assert (pos <= lim);
	int rem = (pos <= lim ? lim - pos : 0);

	if (directIO) {
	Util.checkBufferPositionAligned(bb, pos, alignment);
	Util.checkRemainingBufferSizeAligned(rem, alignment);
	}

	if (rem == 0)
	return 0;
	int n = 0;
	var handle = acquireScope(bb, async);
	try {
	if (position != -1) {
	n = nd.pread(fd, bufferAddress(bb) + pos, rem, position);
	} else {
	n = nd.read(fd, bufferAddress(bb) + pos, rem);
	}
	} finally {
	releaseScope(handle);
	}
	if (n > 0)
	bb.position(pos + n);
	return n;
	}

	static long read(FileDescriptor fd, ByteBuffer[] bufs, NativeDispatcher nd)
	throws IOException
	{
	return read(fd, bufs, 0, bufs.length, false, false, -1, nd);
	}

	static long read(FileDescriptor fd, ByteBuffer[] bufs, boolean async,
	NativeDispatcher nd)
	throws IOException
	{
	return read(fd, bufs, 0, bufs.length, false, async, -1, nd);
	}

	static long read(FileDescriptor fd, ByteBuffer[] bufs, int offset, int length,
	NativeDispatcher nd)
	throws IOException
	{
	return read(fd, bufs, offset, length, false, false, -1, nd);
	}

	static long read(FileDescriptor fd, ByteBuffer[] bufs, int offset, int length,
	boolean directIO, int alignment, NativeDispatcher nd)

	throws IOException
	{
	return read(fd, bufs, offset, length, directIO, false, alignment, nd);
	}

	static long read(FileDescriptor fd, ByteBuffer[] bufs, int offset, int length,
	boolean directIO, boolean async,
	int alignment, NativeDispatcher nd)

	throws IOException
	{
	IOVecWrapper vec = IOVecWrapper.get(length);

	boolean completed = false;
	int iov_len = 0;
	Runnable handleReleasers = null;
	try {
	// Iterate over buffers to populate native iovec array.
	int count = offset + length;
	int i = offset;
	while (i < count && iov_len < IOV_MAX) {
	ByteBuffer buf = bufs[i];
	if (buf.isReadOnly())
	throw new IllegalArgumentException("Read-only buffer");
	var h = acquireScope(buf, async);
	if (h != null) {
	handleReleasers = LinkedRunnable.of(Releaser.of(h), handleReleasers);
	}
	int pos = buf.position();
	int lim = buf.limit();
	assert (pos <= lim);
	int rem = (pos <= lim ? lim - pos : 0);

	if (directIO)
	Util.checkRemainingBufferSizeAligned(rem, alignment);

	if (rem > 0) {
	vec.setBuffer(iov_len, buf, pos, rem);

	// allocate shadow buffer to ensure I/O is done with direct buffer
	if (!(buf instanceof DirectBuffer)) {
	ByteBuffer shadow;
	if (directIO) {
	shadow = Util.getTemporaryAlignedDirectBuffer(rem, alignment);
	} else {
	shadow = Util.getTemporaryDirectBuffer(rem);
	}
	vec.setShadow(iov_len, shadow);
	buf = shadow;
	pos = shadow.position();
	}

	vec.putBase(iov_len, bufferAddress(buf) + pos);
	vec.putLen(iov_len, rem);
	iov_len++;
	}
	i++;
	}
	if (iov_len == 0)
	return 0L;

	long bytesRead = nd.readv(fd, vec.address, iov_len);

	// Notify the buffers how many bytes were read
	long left = bytesRead;
	for (int j=0; j<iov_len; j++) {
	ByteBuffer shadow = vec.getShadow(j);
	if (left > 0) {
	ByteBuffer buf = vec.getBuffer(j);
	int rem = vec.getRemaining(j);
	int n = (left > rem) ? rem : (int)left;
	if (shadow == null) {
	int pos = vec.getPosition(j);
	buf.position(pos + n);
	} else {
	shadow.limit(shadow.position() + n);
	buf.put(shadow);
	}
	left -= n;
	}
	if (shadow != null)
	Util.offerLastTemporaryDirectBuffer(shadow);
	vec.clearRefs(j);
	}

	completed = true;
	return bytesRead;

	} finally {
	releaseScopes(handleReleasers);
	// if an error occurred then clear refs to buffers and return any shadow
	// buffers to cache
	if (!completed) {
	for (int j=0; j<iov_len; j++) {
	ByteBuffer shadow = vec.getShadow(j);
	if (shadow != null)
	Util.offerLastTemporaryDirectBuffer(shadow);
	vec.clearRefs(j);
	}
	}
	}
	}

	private static final JavaNioAccess NIO_ACCESS = SharedSecrets.getJavaNioAccess();

	static Scope.Handle acquireScope(ByteBuffer bb, boolean async) {
	return NIO_ACCESS.acquireScope(bb, async);
	}

	private static void releaseScope(Scope.Handle handle) {
	if (handle == null)
	return;
	try {
	handle.scope().release(handle);
	} catch (Exception e) {
	throw new IllegalStateException(e);
	}
	}

	static Runnable acquireScopes(ByteBuffer[] buffers) {
	return acquireScopes(null, buffers);
	}

	static Runnable acquireScopes(ByteBuffer buf, ByteBuffer[] buffers) {
	if (buffers == null) {
	assert buf != null;
	return IOUtil.Releaser.ofNullable(IOUtil.acquireScope(buf, true));
	} else {
	assert buf == null;
	Runnable handleReleasers = null;
	for (var b : buffers) {
	var h = IOUtil.acquireScope(b, true);
	if (h != null) {
	handleReleasers = IOUtil.LinkedRunnable.of(IOUtil.Releaser.of(h), handleReleasers);
	}
	}
	return handleReleasers;
	}
	}

	static void releaseScopes(Runnable releasers) {
	if (releasers != null)
	releasers.run();
	}

	static record LinkedRunnable(Runnable node, Runnable next)
	implements Runnable
	{
	LinkedRunnable {
	Objects.requireNonNull(node);
	}
	@Override
	public void run() {
	try {
	node.run();
	} finally {
	if (next != null)
	next.run();
	}
	}
	static LinkedRunnable of(Runnable first, Runnable second) {
	return new LinkedRunnable(first, second);
	}
	}

	static record Releaser(Scope.Handle handle) implements Runnable {
	Releaser { Objects.requireNonNull(handle) ; }
	@Override public void run() { releaseScope(handle); }
	static Runnable of(Scope.Handle handle) { return new Releaser(handle); }
	static Runnable ofNullable(Scope.Handle handle) {
	if (handle == null)
	return () -> { };
	return new Releaser(handle);
	}
	}

	static long bufferAddress(ByteBuffer buf) {
	return NIO_ACCESS.getBufferAddress(buf);
	}

	public static FileDescriptor newFD(int i) {
	FileDescriptor fd = new FileDescriptor();
	setfdVal(fd, i);
	return fd;
	}

	static native boolean randomBytes(byte[] someBytes);

	/**
	* Returns two file descriptors for a pipe encoded in a long.
	* The read end of the pipe is returned in the high 32 bits,
	* while the write end is returned in the low 32 bits.
	*/
	static native long makePipe(boolean blocking) throws IOException;

	static native int write1(int fd, byte b) throws IOException;

	/**
	* Read and discard all bytes.
	*/
	static native boolean drain(int fd) throws IOException;

	/**
	* Read and discard at most one byte
	* @return the number of bytes read or IOS_INTERRUPTED
	*/
	static native int drain1(int fd) throws IOException;

	public static native void configureBlocking(FileDescriptor fd,
	boolean blocking)
	throws IOException;

	public static native int fdVal(FileDescriptor fd);

	static native void setfdVal(FileDescriptor fd, int value);

	static native int fdLimit();

	static native int iovMax();

	static native void initIDs();

	/**
	* Used to trigger loading of native libraries
	*/
	public static void load() { }

	static {
	jdk.internal.loader.BootLoader.loadLibrary("net");
	jdk.internal.loader.BootLoader.loadLibrary("nio");
	initIDs();

	IOV_MAX = iovMax();
	}

	}

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