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      1 /* Licensed to the Apache Software Foundation (ASF) under one or more
      2  * contributor license agreements.  See the NOTICE file distributed with
      3  * this work for additional information regarding copyright ownership.
      4  * The ASF licenses this file to You under the Apache License, Version 2.0
      5  * (the "License"); you may not use this file except in compliance with
      6  * the License.  You may obtain a copy of the License at
      7  *
      8  *     http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package java.nio;
     18 
     19 import java.io.Closeable;
     20 import java.io.FileDescriptor;
     21 import java.io.IOException;
     22 import java.nio.channels.ClosedChannelException;
     23 import java.nio.channels.FileChannel;
     24 import java.util.Set;
     25 
     26 import static android.system.OsConstants.*;
     27 import sun.misc.Cleaner;
     28 import sun.nio.ch.DirectBuffer;
     29 import sun.nio.ch.FileChannelImpl;
     30 
     31 /**
     32  * @hide internal use only
     33  */
     34 public final class NioUtils {
     35     private NioUtils() {
     36     }
     37 
     38     public static void freeDirectBuffer(ByteBuffer buffer) {
     39         if (buffer == null) {
     40             return;
     41         }
     42 
     43         DirectByteBuffer dbb = (DirectByteBuffer) buffer;
     44         // Run the cleaner early, if one is defined.
     45         if (dbb.cleaner != null) {
     46             dbb.cleaner.clean();
     47         }
     48 
     49         dbb.memoryRef.free();
     50     }
     51 
     52     /**
     53      * Returns the int file descriptor from within the given FileChannel 'fc'.
     54      */
     55     public static FileDescriptor getFD(FileChannel fc) {
     56         return ((FileChannelImpl) fc).fd;
     57     }
     58 
     59     /**
     60      * Helps bridge between io and nio.
     61      */
     62     public static FileChannel newFileChannel(Closeable ioObject, FileDescriptor fd, int mode) {
     63         boolean readable = (mode & (O_RDONLY | O_RDWR | O_SYNC)) != 0;
     64         boolean writable = (mode & (O_WRONLY | O_RDWR | O_SYNC)) != 0;
     65         boolean append = (mode & O_APPEND) != 0;
     66         return FileChannelImpl.open(fd, null, readable, writable, append, ioObject);
     67     }
     68 
     69     /**
     70      * Exposes the array backing a non-direct ByteBuffer, even if the ByteBuffer is read-only.
     71      * Normally, attempting to access the array backing a read-only buffer throws.
     72      */
     73     public static byte[] unsafeArray(ByteBuffer b) {
     74         return b.array();
     75     }
     76 
     77     /**
     78      * Exposes the array offset for the array backing a non-direct ByteBuffer,
     79      * even if the ByteBuffer is read-only.
     80      */
     81     public static int unsafeArrayOffset(ByteBuffer b) {
     82         return b.arrayOffset();
     83     }
     84 }
     85