/*
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* Copyright (C) 2016 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 com.android.server.storage;
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import android.os.FileUtils;
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import android.os.ParcelFileDescriptor;
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import android.system.ErrnoException;
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import android.system.Os;
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import android.util.SparseArray;
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import com.android.internal.annotations.GuardedBy;
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import com.android.internal.os.FuseUnavailableMountException;
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import com.android.internal.util.Preconditions;
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import com.android.server.NativeDaemonConnectorException;
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import libcore.io.IoUtils;
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import java.util.concurrent.CountDownLatch;
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/**
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* Runnable that delegates FUSE command from the kernel to application.
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* run() blocks until all opened files on the FUSE mount point are closed. So this should be run in
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* a separated thread.
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*/
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public class AppFuseBridge implements Runnable {
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public static final String TAG = "AppFuseBridge";
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/**
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* The path AppFuse is mounted to.
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* The first number is UID who is mounting the FUSE.
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* THe second number is mount ID.
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* The path must be sync with vold.
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*/
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private static final String APPFUSE_MOUNT_NAME_TEMPLATE = "/mnt/appfuse/%d_%d";
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@GuardedBy("this")
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private final SparseArray<MountScope> mScopes = new SparseArray<>();
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@GuardedBy("this")
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private long mNativeLoop;
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public AppFuseBridge() {
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mNativeLoop = native_new();
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}
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public ParcelFileDescriptor addBridge(MountScope mountScope)
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throws FuseUnavailableMountException, NativeDaemonConnectorException {
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try {
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synchronized (this) {
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Preconditions.checkArgument(mScopes.indexOfKey(mountScope.mountId) < 0);
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if (mNativeLoop == 0) {
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throw new FuseUnavailableMountException(mountScope.mountId);
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}
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final int fd = native_add_bridge(
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mNativeLoop, mountScope.mountId, mountScope.open().detachFd());
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if (fd == -1) {
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throw new FuseUnavailableMountException(mountScope.mountId);
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}
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final ParcelFileDescriptor result = ParcelFileDescriptor.adoptFd(fd);
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mScopes.put(mountScope.mountId, mountScope);
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mountScope = null;
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return result;
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}
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} finally {
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IoUtils.closeQuietly(mountScope);
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}
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}
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@Override
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public void run() {
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native_start_loop(mNativeLoop);
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synchronized (this) {
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native_delete(mNativeLoop);
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mNativeLoop = 0;
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}
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}
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public ParcelFileDescriptor openFile(int mountId, int fileId, int mode)
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throws FuseUnavailableMountException, InterruptedException {
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final MountScope scope;
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synchronized (this) {
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scope = mScopes.get(mountId);
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if (scope == null) {
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throw new FuseUnavailableMountException(mountId);
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}
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}
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final boolean result = scope.waitForMount();
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if (result == false) {
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throw new FuseUnavailableMountException(mountId);
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}
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try {
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int flags = FileUtils.translateModePfdToPosix(mode);
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return scope.openFile(mountId, fileId, flags);
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} catch (NativeDaemonConnectorException error) {
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throw new FuseUnavailableMountException(mountId);
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}
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}
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// Used by com_android_server_storage_AppFuse.cpp.
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synchronized private void onMount(int mountId) {
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final MountScope scope = mScopes.get(mountId);
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if (scope != null) {
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scope.setMountResultLocked(true);
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}
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}
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// Used by com_android_server_storage_AppFuse.cpp.
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synchronized private void onClosed(int mountId) {
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final MountScope scope = mScopes.get(mountId);
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if (scope != null) {
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scope.setMountResultLocked(false);
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IoUtils.closeQuietly(scope);
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mScopes.remove(mountId);
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}
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}
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public static abstract class MountScope implements AutoCloseable {
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public final int uid;
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public final int mountId;
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private final CountDownLatch mMounted = new CountDownLatch(1);
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private boolean mMountResult = false;
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public MountScope(int uid, int mountId) {
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this.uid = uid;
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this.mountId = mountId;
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}
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@GuardedBy("AppFuseBridge.this")
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void setMountResultLocked(boolean result) {
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if (mMounted.getCount() == 0) {
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return;
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}
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mMountResult = result;
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mMounted.countDown();
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}
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boolean waitForMount() throws InterruptedException {
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mMounted.await();
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return mMountResult;
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}
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public abstract ParcelFileDescriptor open() throws NativeDaemonConnectorException;
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public abstract ParcelFileDescriptor openFile(int mountId, int fileId, int flags)
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throws NativeDaemonConnectorException;
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}
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private native long native_new();
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private native void native_delete(long loop);
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private native void native_start_loop(long loop);
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private native int native_add_bridge(long loop, int mountId, int deviceId);
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}
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