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 {
NioUtils()35     private NioUtils() {
36     }
37 
freeDirectBuffer(ByteBuffer buffer)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      */
getFD(FileChannel fc)55     public static FileDescriptor getFD(FileChannel fc) {
56         return ((FileChannelImpl) fc).fd;
57     }
58 
59     /**
60      * Helps bridge between io and nio.
61      */
newFileChannel(Closeable ioObject, FileDescriptor fd, int mode)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      */
unsafeArray(ByteBuffer b)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      */
unsafeArrayOffset(ByteBuffer b)81     public static int unsafeArrayOffset(ByteBuffer b) {
82         return b.arrayOffset();
83     }
84 }
85