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 static android.annotation.SystemApi.Client.MODULE_LIBRARIES;
20 
21 import android.annotation.SystemApi;
22 import android.compat.annotation.UnsupportedAppUsage;
23 
24 import java.io.Closeable;
25 import java.io.FileDescriptor;
26 import java.nio.channels.FileChannel;
27 
28 import sun.nio.ch.FileChannelImpl;
29 
30 import static android.system.OsConstants.O_ACCMODE;
31 import static android.system.OsConstants.O_APPEND;
32 import static android.system.OsConstants.O_RDONLY;
33 import static android.system.OsConstants.O_WRONLY;
34 
35 /**
36  * @hide internal use only
37  */
38 @SystemApi(client = MODULE_LIBRARIES)
39 @libcore.api.CorePlatformApi(status = libcore.api.CorePlatformApi.Status.STABLE)
40 public final class NioUtils {
NioUtils()41     private NioUtils() {
42     }
43 
44     /**
45      * Frees {@link DirectByteBuffer} running associated {@link sun.misc.Cleaner Cleaner}.
46      *
47      * @param buffer to free with associated {@code Cleaner}
48      *
49      * @hide
50      */
51     @UnsupportedAppUsage
52     @SystemApi(client = MODULE_LIBRARIES)
53     @libcore.api.CorePlatformApi(status = libcore.api.CorePlatformApi.Status.STABLE)
freeDirectBuffer(ByteBuffer buffer)54     public static void freeDirectBuffer(ByteBuffer buffer) {
55         if (buffer == null) {
56             return;
57         }
58 
59         DirectByteBuffer dbb = (DirectByteBuffer) buffer;
60         // Run the cleaner early, if one is defined.
61         if (dbb.cleaner != null) {
62             dbb.cleaner.clean();
63         }
64 
65         dbb.memoryRef.free();
66     }
67 
68     /**
69      * Returns the int file descriptor from within the given FileChannel 'fc'.
70      *
71      * @hide
72      */
getFD(FileChannel fc)73     public static FileDescriptor getFD(FileChannel fc) {
74         return ((FileChannelImpl) fc).fd;
75     }
76 
77     /**
78      * Helps bridge between io and nio.
79      *
80      * @hide
81      */
newFileChannel(Closeable ioObject, FileDescriptor fd, int mode)82     public static FileChannel newFileChannel(Closeable ioObject, FileDescriptor fd, int mode) {
83         boolean readable = (mode & O_ACCMODE) != O_WRONLY;
84         boolean writable = (mode & O_ACCMODE) != O_RDONLY;
85         boolean append = (mode & O_APPEND) != 0;
86         return FileChannelImpl.open(fd, null, readable, writable, append, ioObject);
87     }
88 
89     /**
90      * Exposes the array backing a non-direct {@link java.nio.ByteBuffer ByteBuffer}, even if
91      * the {@link java.nio.ByteBuffer ByteBuffer} is read-only.
92      * Normally, attempting to access the array backing a read-only buffer throws.
93      *
94      * @param b  {@link java.nio.ByteBuffer ByteBuffer} to access its backing array.
95      * @return   buffer's underlying array.
96      *
97      * @hide
98      */
99     @UnsupportedAppUsage
100     @SystemApi(client = MODULE_LIBRARIES)
101     @libcore.api.CorePlatformApi(status = libcore.api.CorePlatformApi.Status.STABLE)
unsafeArray(ByteBuffer b)102     public static byte[] unsafeArray(ByteBuffer b) {
103         return b.array();
104     }
105 
106     /**
107      * Exposes the array offset for the array backing a non-direct {@link java.nio.ByteBuffer ByteBuffer},
108      * even if the {@link java.nio.ByteBuffer ByteBuffer} is read-only.
109      *
110      * @param b  {@link java.nio.ByteBuffer ByteBuffer} to access its backing array offset.
111      * @return   buffer's underlying array data offset.
112      *
113      * @hide
114      */
115     @UnsupportedAppUsage
116     @SystemApi(client = MODULE_LIBRARIES)
117     @libcore.api.CorePlatformApi(status = libcore.api.CorePlatformApi.Status.STABLE)
unsafeArrayOffset(ByteBuffer b)118     public static int unsafeArrayOffset(ByteBuffer b) {
119         return b.arrayOffset();
120     }
121 }
122