com/android/internal/car/CarServiceHelperService.java

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.internal.car;

import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Binder;
import android.os.IBinder;
import android.os.Parcel;
import android.os.RemoteException;
import android.os.UserHandle;
import android.util.Slog;

import com.android.server.SystemService;
import com.android.internal.car.ICarServiceHelper;

/**
 * System service side companion service for CarService.
 * Starts car service and provide necessary API for CarService. Only for car product.
 */
public class CarServiceHelperService extends SystemService {
    private static final String TAG = "CarServiceHelper";
    private static final String CAR_SERVICE_INTERFACE = "android.car.ICar";
    private final ICarServiceHelperImpl mHelper = new ICarServiceHelperImpl();
    private final Context mContext;
    private IBinder mCarService;
    private final ServiceConnection mCarServiceConnection = new ServiceConnection() {

        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            Slog.i(TAG, "**CarService connected**");
            mCarService = iBinder;
            // Cannot depend on ICar which is defined in CarService, so handle binder call directly
            // instead.
            // void setCarServiceHelper(in IBinder helper)
            Parcel data = Parcel.obtain();
            data.writeInterfaceToken(CAR_SERVICE_INTERFACE);
            data.writeStrongBinder(mHelper.asBinder());
            try {
                mCarService.transact(IBinder.FIRST_CALL_TRANSACTION, // setCarServiceHelper
                        data, null, Binder.FLAG_ONEWAY);
            } catch (RemoteException e) {
                Slog.w(TAG, "RemoteException from car service", e);
                handleCarServiceCrash();
            }
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
            handleCarServiceCrash();
        }
    };

    public CarServiceHelperService(Context context) {
        super(context);
        mContext = context;
    }

    @Override
    public void onStart() {
        Intent intent = new Intent();
        intent.setPackage("com.android.car");
        intent.setAction(CAR_SERVICE_INTERFACE);
        if (!getContext().bindServiceAsUser(intent, mCarServiceConnection, Context.BIND_AUTO_CREATE,
                UserHandle.SYSTEM)) {
            Slog.wtf(TAG, "cannot start car service");
        }
        System.loadLibrary("car-framework-service-jni");
    }

    private void handleCarServiceCrash() {
        //TODO define recovery bahavior
    }

    private static native int nativeForceSuspend(int timeoutMs);

    private class ICarServiceHelperImpl extends ICarServiceHelper.Stub {
       /**
         * Force device to suspend
         *
         * @param timeoutMs
         */
        @Override // Binder call
        public int forceSuspend(int timeoutMs) {
            int retVal;
            mContext.enforceCallingOrSelfPermission(android.Manifest.permission.DEVICE_POWER, null);
            final long ident = Binder.clearCallingIdentity();
            try {
                retVal = nativeForceSuspend(timeoutMs);
            } finally {
                Binder.restoreCallingIdentity(ident);
            }
            return retVal;
        }
    }
}