Ytai Ben-Tsvi | 4659e18 | 2019-11-06 09:53:34 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2019 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * 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 android.os; |
| 18 | |
| 19 | import android.annotation.IntRange; |
| 20 | import android.annotation.NonNull; |
| 21 | import android.annotation.Nullable; |
| 22 | import android.annotation.SystemApi; |
| 23 | import android.annotation.TestApi; |
| 24 | |
| 25 | import java.io.Closeable; |
| 26 | import java.io.IOException; |
| 27 | |
| 28 | /** |
| 29 | * An abstract representation of a memory block, as representing by the HIDL system. |
| 30 | * |
| 31 | * The block is defined by a {name, size, handle} tuple, where the name is used to determine how to |
| 32 | * interpret the handle. The underlying handle is assumed to be owned by this instance and will be |
| 33 | * closed as soon as {@link #close()} is called on this instance, or this instance has been |
| 34 | * finalized (the latter supports using it in a shared manner without having to worry about who owns |
| 35 | * this instance, the former is more efficient resource-wise and is recommended for most use-cases). |
| 36 | * Note, however, that ownership of the handle does not necessarily imply ownership of the |
| 37 | * underlying file descriptors - the underlying handle may or may not own them. If you want the |
| 38 | * underlying handle to outlive this instance, call {@link #releaseHandle()} to obtain the handle |
| 39 | * and detach the ownership relationship. |
| 40 | * |
| 41 | * @hide |
| 42 | */ |
| 43 | @SystemApi |
| 44 | @TestApi |
| 45 | public class HidlMemory implements Closeable { |
| 46 | private final @NonNull String mName; |
| 47 | private final long mSize; |
| 48 | private @Nullable NativeHandle mHandle; |
| 49 | private long mNativeContext; // For use of native code. |
| 50 | |
| 51 | /** |
| 52 | * Constructor. |
| 53 | * |
| 54 | * @param name The name of the IMapper service used to resolve the handle (e.g. "ashmem"). |
| 55 | * @param size The (non-negative) size in bytes of the memory block. |
| 56 | * @param handle The handle. May be null. This instance will own the handle and will close it |
| 57 | * as soon as {@link #close()} is called or the object is destroyed. This, this |
| 58 | * handle instance should generally not be shared with other clients. |
| 59 | */ |
| 60 | public HidlMemory(@NonNull String name, @IntRange(from = 0) long size, |
| 61 | @Nullable NativeHandle handle) { |
| 62 | mName = name; |
| 63 | mSize = size; |
| 64 | mHandle = handle; |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * Create a copy of this instance, where the underlying handle (and its file descriptors) have |
| 69 | * been duplicated. |
| 70 | */ |
| 71 | @NonNull |
| 72 | public HidlMemory dup() throws IOException { |
| 73 | return new HidlMemory(mName, mSize, mHandle != null ? mHandle.dup() : null); |
| 74 | } |
| 75 | |
| 76 | /** |
| 77 | * Close the underlying native handle. No-op if handle is null or has been released using {@link |
| 78 | * #releaseHandle()}. |
| 79 | */ |
| 80 | @Override |
| 81 | public void close() throws IOException { |
| 82 | if (mHandle != null) { |
| 83 | mHandle.close(); |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | * Disowns the underlying handle and returns it. This object becomes invalid. |
| 89 | * |
| 90 | * @return The underlying handle. |
| 91 | */ |
| 92 | @NonNull |
| 93 | public NativeHandle releaseHandle() { |
| 94 | NativeHandle handle = mHandle; |
| 95 | mHandle = null; |
| 96 | return handle; |
| 97 | } |
| 98 | |
| 99 | /** |
| 100 | * Gets the name, which represents how the handle is to be interpreted. |
| 101 | * |
| 102 | * @return The name. |
| 103 | */ |
| 104 | @NonNull |
| 105 | public String getName() { |
| 106 | return mName; |
| 107 | } |
| 108 | |
| 109 | /** |
| 110 | * Gets the size of the block, in bytes. |
| 111 | * |
| 112 | * @return The size. |
| 113 | */ |
| 114 | public long getSize() { |
| 115 | return mSize; |
| 116 | } |
| 117 | |
| 118 | /** |
| 119 | * Gets a native handle. The actual interpretation depends on the name and is implementation |
| 120 | * defined. |
| 121 | * |
| 122 | * @return The native handle. |
| 123 | */ |
| 124 | @Nullable |
| 125 | public NativeHandle getHandle() { |
| 126 | return mHandle; |
| 127 | } |
| 128 | |
| 129 | @Override |
| 130 | protected void finalize() { |
| 131 | try { |
| 132 | close(); |
| 133 | } catch (IOException e) { |
| 134 | throw new RuntimeException(e); |
| 135 | } finally { |
| 136 | nativeFinalize(); |
| 137 | } |
| 138 | } |
| 139 | |
| 140 | private native void nativeFinalize(); |
| 141 | } |