141 lines
4.4 KiB
Java
141 lines
4.4 KiB
Java
/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.os;
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import android.annotation.IntRange;
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import android.annotation.NonNull;
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import android.annotation.Nullable;
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import android.annotation.SystemApi;
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import java.io.Closeable;
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import java.io.IOException;
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/**
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* An abstract representation of a memory block, as representing by the HIDL system.
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*
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* The block is defined by a {name, size, handle} tuple, where the name is used to determine how to
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* interpret the handle. The underlying handle is assumed to be owned by this instance and will be
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* closed as soon as {@link #close()} is called on this instance, or this instance has been
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* finalized (the latter supports using it in a shared manner without having to worry about who owns
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* this instance, the former is more efficient resource-wise and is recommended for most use-cases).
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* Note, however, that ownership of the handle does not necessarily imply ownership of the
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* underlying file descriptors - the underlying handle may or may not own them. If you want the
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* underlying handle to outlive this instance, call {@link #releaseHandle()} to obtain the handle
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* and detach the ownership relationship.
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*
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* @hide
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*/
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@SystemApi
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public class HidlMemory implements Closeable {
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private final @NonNull String mName;
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private final long mSize;
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private @Nullable NativeHandle mHandle;
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private long mNativeContext; // For use of native code.
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/**
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* Constructor.
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*
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* @param name The name of the IMapper service used to resolve the handle (e.g. "ashmem").
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* @param size The (non-negative) size in bytes of the memory block.
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* @param handle The handle. May be null. This instance will own the handle and will close it
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* as soon as {@link #close()} is called or the object is destroyed. This, this
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* handle instance should generally not be shared with other clients.
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*/
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public HidlMemory(@NonNull String name, @IntRange(from = 0) long size,
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@Nullable NativeHandle handle) {
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mName = name;
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mSize = size;
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mHandle = handle;
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}
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/**
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* Create a copy of this instance, where the underlying handle (and its file descriptors) have
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* been duplicated.
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*/
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@NonNull
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public HidlMemory dup() throws IOException {
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return new HidlMemory(mName, mSize, mHandle != null ? mHandle.dup() : null);
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}
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/**
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* Close the underlying native handle. No-op if handle is null or has been released using {@link
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* #releaseHandle()}.
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*/
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@Override
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public void close() throws IOException {
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if (mHandle != null) {
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mHandle.close();
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mHandle = null;
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}
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}
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/**
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* Disowns the underlying handle and returns it. The underlying handle becomes null.
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*
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* @return The underlying handle.
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*/
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@Nullable
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public NativeHandle releaseHandle() {
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NativeHandle handle = mHandle;
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mHandle = null;
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return handle;
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}
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/**
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* Gets the name, which represents how the handle is to be interpreted.
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*
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* @return The name.
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*/
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@NonNull
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public String getName() {
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return mName;
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}
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/**
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* Gets the size of the block, in bytes.
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*
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* @return The size.
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*/
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public long getSize() {
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return mSize;
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}
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/**
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* Gets a native handle. The actual interpretation depends on the name and is implementation
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* defined.
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*
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* @return The native handle.
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*/
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@Nullable
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public NativeHandle getHandle() {
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return mHandle;
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}
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@Override
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protected void finalize() {
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try {
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close();
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} catch (IOException e) {
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throw new RuntimeException(e);
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} finally {
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nativeFinalize();
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}
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}
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private native void nativeFinalize();
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}
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