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/**
 * junixsocket
 *
 * Copyright (c) 2009,2014 Christian Kohlschütter
 *
 * The author licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.newsclub.net.unix;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketAddress;
import java.net.SocketException;

/**
 * The server part of an AF_UNIX domain socket.
 * 
 * @author Christian Kohlschütter
 */
public class AFUNIXServerSocket extends ServerSocket {
  private final AFUNIXSocketImpl implementation;
  private AFUNIXSocketAddress boundEndpoint = null;

  private final Thread shutdownThread = new Thread() {
    @Override
    public void run() {
      try {
        if (boundEndpoint != null) {
          NativeUnixSocket.unlink(boundEndpoint.getSocketFile());
        }
      } catch (IOException e) {
        // ignore
      }
    }
  };

  protected AFUNIXServerSocket() throws IOException {
    super();
    this.implementation = new AFUNIXSocketImpl();
    NativeUnixSocket.initServerImpl(this, implementation);

    Runtime.getRuntime().addShutdownHook(shutdownThread);
    NativeUnixSocket.setCreatedServer(this);
  }

  /**
   * Returns a new, unbound AF_UNIX {@link ServerSocket}.
   * 
   * @return The new, unbound {@link AFUNIXServerSocket}.
   */
  public static AFUNIXServerSocket newInstance() throws IOException {
    AFUNIXServerSocket instance = new AFUNIXServerSocket();
    return instance;
  }

  /**
   * Returns a new AF_UNIX {@link ServerSocket} that is bound to the given
   * {@link AFUNIXSocketAddress}.
   * 
   * @return The new, unbound {@link AFUNIXServerSocket}.
   */
  public static AFUNIXServerSocket bindOn(final AFUNIXSocketAddress addr) throws IOException {
    AFUNIXServerSocket socket = newInstance();
    socket.bind(addr);
    return socket;
  }

  @Override
  public void bind(SocketAddress endpoint, int backlog) throws IOException {
    if (isClosed()) {
      throw new SocketException("Socket is closed");
    }
    if (isBound()) {
      throw new SocketException("Already bound");
    }
    if (!(endpoint instanceof AFUNIXSocketAddress)) {
      throw new IOException("Can only bind to endpoints of type "
          + AFUNIXSocketAddress.class.getName());
    }
    implementation.bind(backlog, endpoint);
    boundEndpoint = (AFUNIXSocketAddress) endpoint;
  }

  @Override
  public boolean isBound() {
    return boundEndpoint != null;
  }

  @Override
  public Socket accept() throws IOException {
    if (isClosed()) {
      throw new SocketException("Socket is closed");
    }
    AFUNIXSocket as = AFUNIXSocket.newInstance();
    implementation.accept(as.impl);
    as.addr = boundEndpoint;
    NativeUnixSocket.setConnected(as);
    return as;
  }

  @Override
  public String toString() {
    if (!isBound()) {
      return "AFUNIXServerSocket[unbound]";
    }
    return "AFUNIXServerSocket[" + boundEndpoint.getSocketFile() + "]";
  }

  @Override
  public void close() throws IOException {
    if (isClosed()) {
      return;
    }

    super.close();
    implementation.close();
    if (boundEndpoint != null) {
      NativeUnixSocket.unlink(boundEndpoint.getSocketFile());
    }
    try {
      Runtime.getRuntime().removeShutdownHook(shutdownThread);
    } catch (IllegalStateException e) {
      // ignore
    }
  }

  public static boolean isSupported() {
    return NativeUnixSocket.isLoaded();
  }
}