/*
 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */
package java.net;

import jdk.internal.misc.JavaIOFileDescriptorAccess;
import jdk.internal.misc.SharedSecrets;
import jdk.internal.ref.CleanerFactory;
import jdk.internal.ref.PhantomCleanable;

import java.io.FileDescriptor;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.lang.ref.Cleaner;


/**
 * Cleanable for a socket/datagramsocket FileDescriptor when it becomes phantom reachable.
 * Create a cleanup if the raw fd != -1. Windows closes sockets using the fd.
 * Subclassed from {@code PhantomCleanable} so that {@code clear} can be
 * called to disable the cleanup when the socket fd is closed by any means
 * other than calling {@link FileDescriptor#close}.
 * Otherwise, it might incorrectly close the handle or fd after it has been reused.
 */
final class SocketCleanable extends PhantomCleanable<FileDescriptor> {

 // Access to FileDescriptor private fields
 private static final JavaIOFileDescriptorAccess fdAccess =
 SharedSecrets.getJavaIOFileDescriptorAccess();

 // Native function to call NET_SocketClose(fd)
 // Used only for last chance cleanup.
 private static native void cleanupClose0(int fd) throws IOException;

 // The raw fd to close
 private final int fd;

 /**
 * Register a socket specific Cleanable with the FileDescriptor
 * if the FileDescriptor is non-null and the raw fd is != -1.
 *
 * @param fdo the FileDescriptor; may be null
 */
 static void register(FileDescriptor fdo) {
 if (fdo != null && fdo.valid()) {
 int fd = fdAccess.get(fdo);
 fdAccess.registerCleanup(fdo,
 new SocketCleanable(fdo, CleanerFactory.cleaner(), fd));
 }
 }

 /**
 * Unregister a Cleanable from the FileDescriptor.
 * @param fdo the FileDescriptor; may be null
 */
 static void unregister(FileDescriptor fdo) {
 if (fdo != null) {
 fdAccess.unregisterCleanup(fdo);
 }
 }

 /**
 * Constructor for a phantom cleanable reference.
 *
 * @param obj the object to monitor
 * @param cleaner the cleaner
 * @param fd file descriptor to close
 */
 private SocketCleanable(FileDescriptor obj, Cleaner cleaner, int fd) {
 super(obj, cleaner);
 this.fd = fd;
 }

 /**
 * Close the native handle or fd.
 */
 @Override
 protected void performCleanup() {
 try {
 cleanupClose0(fd);
 } catch (IOException ioe) {
 throw new UncheckedIOException("close", ioe);
 }
 }
}