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   /*
    * Copyright 2016 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty.channel.unix;
  
  import io.netty.buffer.ByteBufAllocator;
  import io.netty.util.internal.ObjectUtil;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.channels.WritableByteChannel;
  
  public abstract class SocketWritableByteChannel implements WritableByteChannel {
      protected final FileDescriptor fd;
  
      protected SocketWritableByteChannel(FileDescriptor fd) {
          this.fd = ObjectUtil.checkNotNull(fd, "fd");
      }
  
      protected int write(ByteBuffer buf, int pos, int limit) throws IOException {
          return fd.write(buf, pos, limit);
      }
  
      @Override
      public final int write(java.nio.ByteBuffer src) throws java.io.IOException {
          final int written;
          int position = src.position();
          int limit = src.limit();
          if (src.isDirect()) {
              written = write(src, position, src.limit());
          } else {
              final int readableBytes = limit - position;
              io.netty.buffer.ByteBuf buffer = null;
              try {
                  if (readableBytes == 0) {
                      buffer = io.netty.buffer.Unpooled.EMPTY_BUFFER;
                  } else {
                      final ByteBufAllocator alloc = alloc();
                      if (alloc.isDirectBufferPooled()) {
                          buffer = alloc.directBuffer(readableBytes);
                      } else {
                          buffer = io.netty.buffer.ByteBufUtil.threadLocalDirectBuffer();
                          if (buffer == null) {
                              buffer = io.netty.buffer.Unpooled.directBuffer(readableBytes);
                          }
                      }
                  }
                  buffer.writeBytes(src.duplicate());
                  java.nio.ByteBuffer nioBuffer = buffer.internalNioBuffer(buffer.readerIndex(), readableBytes);
                  written = write(nioBuffer, nioBuffer.position(), nioBuffer.limit());
              } finally {
                  if (buffer != null) {
                      buffer.release();
                  }
              }
          }
          if (written > 0) {
              src.position(position + written);
          }
          return written;
      }
  
      @Override
      public final boolean isOpen() {
          return fd.isOpen();
      }
  
      @Override
      public final void close() throws java.io.IOException {
          fd.close();
      }
  
      protected abstract ByteBufAllocator alloc();
  }