server/tv/TvInputManagerService.java

/*
 * Copyright (C) 2014 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.server.tv;

import android.app.ActivityManager;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.ServiceConnection;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.content.pm.ServiceInfo;
import android.net.Uri;
import android.os.Binder;
import android.os.IBinder;
import android.os.Process;
import android.os.RemoteException;
import android.os.UserHandle;
import android.tv.ITvInputClient;
import android.tv.ITvInputManager;
import android.tv.ITvInputService;
import android.tv.ITvInputServiceCallback;
import android.tv.ITvInputSession;
import android.tv.ITvInputSessionCallback;
import android.tv.TvInputInfo;
import android.tv.TvInputService;
import android.util.ArrayMap;
import android.util.Log;
import android.util.SparseArray;
import android.view.Surface;

import com.android.internal.content.PackageMonitor;
import com.android.server.SystemService;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/** This class provides a system service that manages television inputs. */
public final class TvInputManagerService extends SystemService {
    // STOPSHIP: Turn debugging off.
    private static final boolean DEBUG = true;
    private static final String TAG = "TvInputManagerService";

    private final Context mContext;

    // A global lock.
    private final Object mLock = new Object();

    // ID of the current user.
    private int mCurrentUserId = UserHandle.USER_OWNER;

    // A map from user id to UserState.
    private final SparseArray<UserState> mUserStates = new SparseArray<UserState>();

    public TvInputManagerService(Context context) {
        super(context);
        mContext = context;
        registerBroadcastReceivers();
        synchronized (mLock) {
            mUserStates.put(mCurrentUserId, new UserState());
            buildTvInputListLocked(mCurrentUserId);
        }
    }

    @Override
    public void onStart() {
        publishBinderService(Context.TV_INPUT_SERVICE, new BinderService());
    }

    private void registerBroadcastReceivers() {
        PackageMonitor monitor = new PackageMonitor() {
            @Override
            public void onSomePackagesChanged() {
                synchronized (mLock) {
                    buildTvInputListLocked(mCurrentUserId);
                }
            }
        };
        monitor.register(mContext, null, UserHandle.ALL, true);

        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(Intent.ACTION_USER_SWITCHED);
        intentFilter.addAction(Intent.ACTION_USER_REMOVED);
        mContext.registerReceiverAsUser(new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();
                if (Intent.ACTION_USER_SWITCHED.equals(action)) {
                    switchUser(intent.getIntExtra(Intent.EXTRA_USER_HANDLE, 0));
                } else if (Intent.ACTION_USER_REMOVED.equals(action)) {
                    removeUser(intent.getIntExtra(Intent.EXTRA_USER_HANDLE, 0));
                }
            }
        }, UserHandle.ALL, intentFilter, null, null);
    }

    private void buildTvInputListLocked(int userId) {
        UserState userState = getUserStateLocked(userId);
        userState.inputList.clear();

        PackageManager pm = mContext.getPackageManager();
        List<ResolveInfo> services = pm.queryIntentServices(
                new Intent(TvInputService.SERVICE_INTERFACE), PackageManager.GET_SERVICES);
        for (ResolveInfo ri : services) {
            ServiceInfo si = ri.serviceInfo;
            if (!android.Manifest.permission.BIND_TV_INPUT.equals(si.permission)) {
                Log.w(TAG, "Skipping TV input " + si.name + ": it does not require the permission "
                        + android.Manifest.permission.BIND_TV_INPUT);
                continue;
            }
            TvInputInfo info = new TvInputInfo(ri);
            userState.inputList.add(info);
        }
    }

    private void switchUser(int userId) {
        synchronized (mLock) {
            if (mCurrentUserId == userId) {
                return;
            }
            // final int oldUserId = mCurrentUserId;
            // TODO: Release services and sessions in the old user state, if needed.
            mCurrentUserId = userId;

            UserState userState = mUserStates.get(userId);
            if (userState == null) {
                userState = new UserState();
            }
            mUserStates.put(userId, userState);
            buildTvInputListLocked(userId);
        }
    }

    private void removeUser(int userId) {
        synchronized (mLock) {
            UserState userState = mUserStates.get(userId);
            if (userState == null) {
                return;
            }
            // Release created sessions.
            for (SessionState state : userState.sessionStateMap.values()) {
                if (state.session != null) {
                    try {
                        state.session.release();
                    } catch (RemoteException e) {
                        Log.e(TAG, "error in release", e);
                    }
                }
            }
            userState.sessionStateMap.clear();

            // Unregister all callbacks and unbind all services.
            for (ServiceState serviceState : userState.serviceStateMap.values()) {
                if (serviceState.callback != null) {
                    try {
                        serviceState.service.unregisterCallback(serviceState.callback);
                    } catch (RemoteException e) {
                        Log.e(TAG, "error in unregisterCallback", e);
                    }
                }
                serviceState.clients.clear();
                mContext.unbindService(serviceState.connection);
            }
            userState.serviceStateMap.clear();

            mUserStates.remove(userId);
        }
    }

    private UserState getUserStateLocked(int userId) {
        UserState userState = mUserStates.get(userId);
        if (userState == null) {
            throw new IllegalStateException("User state not found for user ID " + userId);
        }
        return userState;
    }

    private ServiceState getServiceStateLocked(ComponentName name, int userId) {
        UserState userState = getUserStateLocked(userId);
        ServiceState serviceState = userState.serviceStateMap.get(name);
        if (serviceState == null) {
            throw new IllegalStateException("Service state not found for " + name + " (userId="
                    + userId + ")");
        }
        return serviceState;
    }

    private ITvInputSession getSessionLocked(IBinder sessionToken, int callingUid, int userId) {
        UserState userState = getUserStateLocked(userId);
        SessionState sessionState = userState.sessionStateMap.get(sessionToken);
        if (sessionState == null) {
            throw new IllegalArgumentException("Session state not found for token " + sessionToken);
        }
        // Only the application that requested this session or the system can access it.
        if (callingUid != Process.SYSTEM_UID && callingUid != sessionState.callingUid) {
            throw new SecurityException("Illegal access to the session with token " + sessionToken
                    + " from uid " + callingUid);
        }
        ITvInputSession session = sessionState.session;
        if (session == null) {
            throw new IllegalStateException("Session not yet created for token " + sessionToken);
        }
        return session;
    }

    private int resolveCallingUserId(int callingPid, int callingUid, int requestedUserId,
            String methodName) {
        return ActivityManager.handleIncomingUser(callingPid, callingUid, requestedUserId, false,
                false, methodName, null);
    }

    private void updateServiceConnectionLocked(ComponentName name, int userId) {
        UserState userState = getUserStateLocked(userId);
        ServiceState serviceState = userState.serviceStateMap.get(name);
        if (serviceState == null) {
            return;
        }
        boolean isStateEmpty = serviceState.clients.isEmpty()
                && serviceState.sessionTokens.isEmpty();
        if (serviceState.service == null && !isStateEmpty && userId == mCurrentUserId) {
            // This means that the service is not yet connected but its state indicates that we
            // have pending requests. Then, connect the service.
            if (serviceState.bound) {
                // We have already bound to the service so we don't try to bind again until after we
                // unbind later on.
                return;
            }
            if (DEBUG) {
                Log.i(TAG, "bindServiceAsUser(name=" + name.getClassName() + ", userId=" + userId
                        + ")");
            }
            Intent i = new Intent(TvInputService.SERVICE_INTERFACE).setComponent(name);
            mContext.bindServiceAsUser(i, serviceState.connection, Context.BIND_AUTO_CREATE,
                    new UserHandle(userId));
            serviceState.bound = true;
        } else if (serviceState.service != null && isStateEmpty) {
            // This means that the service is already connected but its state indicates that we have
            // nothing to do with it. Then, disconnect the service.
            if (DEBUG) {
                Log.i(TAG, "unbindService(name=" + name.getClassName() + ")");
            }
            mContext.unbindService(serviceState.connection);
            userState.serviceStateMap.remove(name);
        }
    }

    private void createSessionInternalLocked(ITvInputService service, final IBinder sessionToken,
            final int userId) {
        final SessionState sessionState =
                getUserStateLocked(userId).sessionStateMap.get(sessionToken);
        if (DEBUG) {
            Log.d(TAG, "createSessionInternalLocked(name=" + sessionState.name.getClassName()
                    + ")");
        }
        // Set up a callback to send the session token.
        ITvInputSessionCallback callback = new ITvInputSessionCallback.Stub() {
            @Override
            public void onSessionCreated(ITvInputSession session) {
                if (DEBUG) {
                    Log.d(TAG, "onSessionCreated(name=" + sessionState.name.getClassName() + ")");
                }
                synchronized (mLock) {
                    sessionState.session = session;
                    if (session == null) {
                        removeSessionStateLocked(sessionToken, userId);
                        sendSessionTokenToClientLocked(sessionState.client, sessionState.name, null,
                                sessionState.seq, userId);
                    } else {
                        sendSessionTokenToClientLocked(sessionState.client, sessionState.name,
                                sessionToken, sessionState.seq, userId);
                    }
                }
            }
        };

        // Create a session. When failed, send a null token immediately.
        try {
            service.createSession(callback);
        } catch (RemoteException e) {
            Log.e(TAG, "error in createSession", e);
            removeSessionStateLocked(sessionToken, userId);
            sendSessionTokenToClientLocked(sessionState.client, sessionState.name, null,
                    sessionState.seq, userId);
        }
    }

    private void sendSessionTokenToClientLocked(ITvInputClient client, ComponentName name,
            IBinder sessionToken, int seq, int userId) {
        try {
            client.onSessionCreated(name, sessionToken, seq);
        } catch (RemoteException exception) {
            Log.e(TAG, "error in onSessionCreated", exception);
        }

        if (sessionToken == null) {
            // This means that the session creation failed. We might want to disconnect the service.
            updateServiceConnectionLocked(name, userId);
        }
    }

    private void removeSessionStateLocked(IBinder sessionToken, int userId) {
        // Remove the session state from the global session state map of the current user.
        UserState userState = getUserStateLocked(userId);
        SessionState sessionState = userState.sessionStateMap.remove(sessionToken);

        // Also remove the session token from the session token list of the current service.
        ServiceState serviceState = userState.serviceStateMap.get(sessionState.name);
        if (serviceState != null) {
            serviceState.sessionTokens.remove(sessionToken);
        }
        updateServiceConnectionLocked(sessionState.name, userId);
    }

    private final class BinderService extends ITvInputManager.Stub {
        @Override
        public List<TvInputInfo> getTvInputList(int userId) {
            final int resolvedUserId = resolveCallingUserId(Binder.getCallingPid(),
                    Binder.getCallingUid(), userId, "getTvInputList");
            final long identity = Binder.clearCallingIdentity();
            try {
                synchronized (mLock) {
                    UserState userState = getUserStateLocked(resolvedUserId);
                    return new ArrayList<TvInputInfo>(userState.inputList);
                }
            } finally {
                Binder.restoreCallingIdentity(identity);
            }
        }

        @Override
        public boolean getAvailability(final ITvInputClient client, final ComponentName name,
                int userId) {
            final int resolvedUserId = resolveCallingUserId(Binder.getCallingPid(),
                    Binder.getCallingUid(), userId, "getAvailability");
            final long identity = Binder.clearCallingIdentity();
            try {
                synchronized (mLock) {
                    UserState userState = getUserStateLocked(resolvedUserId);
                    ServiceState serviceState = userState.serviceStateMap.get(name);
                    if (serviceState != null) {
                        // We already know the status of this input service. Return the cached
                        // status.
                        return serviceState.available;
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(identity);
            }
            return false;
        }

        @Override
        public void registerCallback(final ITvInputClient client, final ComponentName name,
                int userId) {
            final int resolvedUserId = resolveCallingUserId(Binder.getCallingPid(),
                    Binder.getCallingUid(), userId, "registerCallback");
            final long identity = Binder.clearCallingIdentity();
            try {
                synchronized (mLock) {
                    // Create a new service callback and add it to the callback map of the current
                    // service.
                    UserState userState = getUserStateLocked(resolvedUserId);
                    ServiceState serviceState = userState.serviceStateMap.get(name);
                    if (serviceState == null) {
                        serviceState = new ServiceState(name, resolvedUserId);
                        userState.serviceStateMap.put(name, serviceState);
                    }
                    IBinder iBinder = client.asBinder();
                    if (!serviceState.clients.contains(iBinder)) {
                        serviceState.clients.add(iBinder);
                    }
                    if (serviceState.service != null) {
                        if (serviceState.callback != null) {
                            // We already handled.
                            return;
                        }
                        serviceState.callback = new ServiceCallback(resolvedUserId);
                        try {
                            serviceState.service.registerCallback(serviceState.callback);
                        } catch (RemoteException e) {
                            Log.e(TAG, "error in registerCallback", e);
                        }
                    } else {
                        updateServiceConnectionLocked(name, resolvedUserId);
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(identity);
            }
        }

        @Override
        public void unregisterCallback(ITvInputClient client, ComponentName name, int userId) {
            final int resolvedUserId = resolveCallingUserId(Binder.getCallingPid(),
                    Binder.getCallingUid(), userId, "unregisterCallback");
            final long identity = Binder.clearCallingIdentity();
            try {
                synchronized (mLock) {
                    UserState userState = getUserStateLocked(resolvedUserId);
                    ServiceState serviceState = userState.serviceStateMap.get(name);
                    if (serviceState == null) {
                        return;
                    }

                    // Remove this client from the client list and unregister the callback.
                    serviceState.clients.remove(client.asBinder());
                    if (!serviceState.clients.isEmpty()) {
                        // We have other clients who want to keep the callback. Do this later.
                        return;
                    }
                    if (serviceState.service == null || serviceState.callback == null) {
                        return;
                    }
                    try {
                        serviceState.service.unregisterCallback(serviceState.callback);
                    } catch (RemoteException e) {
                        Log.e(TAG, "error in unregisterCallback", e);
                    } finally {
                        serviceState.callback = null;
                        updateServiceConnectionLocked(name, resolvedUserId);
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(identity);
            }
        }

        @Override
        public void createSession(final ITvInputClient client, final ComponentName name,
                int seq, int userId) {
            final int callingUid = Binder.getCallingUid();
            final int resolvedUserId = resolveCallingUserId(Binder.getCallingPid(), callingUid,
                    userId, "createSession");
            final long identity = Binder.clearCallingIdentity();
            try {
                synchronized (mLock) {
                    // Create a new session token and a session state.
                    IBinder sessionToken = new Binder();
                    SessionState sessionState = new SessionState(name, client, seq, callingUid);
                    sessionState.session = null;

                    // Add them to the global session state map of the current user.
                    UserState userState = getUserStateLocked(resolvedUserId);
                    userState.sessionStateMap.put(sessionToken, sessionState);

                    // Also, add them to the session state map of the current service.
                    ServiceState serviceState = userState.serviceStateMap.get(name);
                    if (serviceState == null) {
                        serviceState = new ServiceState(name, resolvedUserId);
                        userState.serviceStateMap.put(name, serviceState);
                    }
                    serviceState.sessionTokens.add(sessionToken);

                    if (serviceState.service != null) {
                        createSessionInternalLocked(serviceState.service, sessionToken,
                                resolvedUserId);
                    } else {
                        updateServiceConnectionLocked(name, resolvedUserId);
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(identity);
            }
        }

        @Override
        public void releaseSession(IBinder sessionToken, int userId) {
            final int callingUid = Binder.getCallingUid();
            final int resolvedUserId = resolveCallingUserId(Binder.getCallingPid(), callingUid,
                    userId, "releaseSession");
            final long identity = Binder.clearCallingIdentity();
            try {
                synchronized (mLock) {
                    // Release the session.
                    try {
                        getSessionLocked(sessionToken, callingUid, resolvedUserId).release();
                    } catch (RemoteException e) {
                        Log.e(TAG, "error in release", e);
                    }

                    removeSessionStateLocked(sessionToken, resolvedUserId);
                }
            } finally {
                Binder.restoreCallingIdentity(identity);
            }
        }

        @Override
        public void setSurface(IBinder sessionToken, Surface surface, int userId) {
            final int callingUid = Binder.getCallingUid();
            final int resolvedUserId = resolveCallingUserId(Binder.getCallingPid(), callingUid,
                    userId, "setSurface");
            final long identity = Binder.clearCallingIdentity();
            try {
                synchronized (mLock) {
                    try {
                        getSessionLocked(sessionToken, callingUid, resolvedUserId).setSurface(
                                surface);
                    } catch (RemoteException e) {
                        Log.e(TAG, "error in setSurface", e);
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(identity);
            }
        }

        @Override
        public void setVolume(IBinder sessionToken, float volume, int userId) {
            final int callingUid = Binder.getCallingUid();
            final int resolvedUserId = resolveCallingUserId(Binder.getCallingPid(), callingUid,
                    userId, "setVolume");
            final long identity = Binder.clearCallingIdentity();
            try {
                synchronized (mLock) {
                    try {
                        getSessionLocked(sessionToken, callingUid, resolvedUserId).setVolume(
                                volume);
                    } catch (RemoteException e) {
                        Log.e(TAG, "error in setVolume", e);
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(identity);
            }
        }

        @Override
        public void tune(IBinder sessionToken, final Uri channelUri, int userId) {
            final int callingUid = Binder.getCallingUid();
            final int resolvedUserId = resolveCallingUserId(Binder.getCallingPid(), callingUid,
                    userId, "tune");
            final long identity = Binder.clearCallingIdentity();
            try {
                synchronized (mLock) {
                    SessionState sessionState = getUserStateLocked(resolvedUserId)
                            .sessionStateMap.get(sessionToken);
                    final String serviceName = sessionState.name.getClassName();
                    try {
                        getSessionLocked(sessionToken, callingUid, resolvedUserId).tune(channelUri);
                    } catch (RemoteException e) {
                        Log.e(TAG, "error in tune", e);
                        return;
                    }
                }
            } finally {
                Binder.restoreCallingIdentity(identity);
            }
        }
    }

    private static final class UserState {
        // A list of all known TV inputs on the system.
        private final List<TvInputInfo> inputList = new ArrayList<TvInputInfo>();

        // A mapping from the name of a TV input service to its state.
        private final Map<ComponentName, ServiceState> serviceStateMap =
                new HashMap<ComponentName, ServiceState>();

        // A mapping from the token of a TV input session to its state.
        private final Map<IBinder, SessionState> sessionStateMap =
                new HashMap<IBinder, SessionState>();
    }

    private final class ServiceState {
        private final List<IBinder> clients = new ArrayList<IBinder>();
        private final List<IBinder> sessionTokens = new ArrayList<IBinder>();
        private final ServiceConnection connection;

        private ITvInputService service;
        private ServiceCallback callback;
        private boolean bound;
        private boolean available;

        private ServiceState(ComponentName name, int userId) {
            this.connection = new InputServiceConnection(userId);
        }
    }

    private static final class SessionState {
        private final ComponentName name;
        private final ITvInputClient client;
        private final int seq;
        private final int callingUid;

        private ITvInputSession session;

        private SessionState(ComponentName name, ITvInputClient client, int seq, int callingUid) {
            this.name = name;
            this.client = client;
            this.seq = seq;
            this.callingUid = callingUid;
        }
    }

    private final class InputServiceConnection implements ServiceConnection {
        private final int mUserId;

        private InputServiceConnection(int userId) {
            mUserId = userId;
        }

        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            if (DEBUG) {
                Log.d(TAG, "onServiceConnected(name=" + name.getClassName() + ")");
            }
            synchronized (mLock) {
                ServiceState serviceState = getServiceStateLocked(name, mUserId);
                serviceState.service = ITvInputService.Stub.asInterface(service);

                // Register a callback, if we need to.
                if (!serviceState.clients.isEmpty() && serviceState.callback == null) {
                    serviceState.callback = new ServiceCallback(mUserId);
                    try {
                        serviceState.service.registerCallback(serviceState.callback);
                    } catch (RemoteException e) {
                        Log.e(TAG, "error in registerCallback", e);
                    }
                }

                // And create sessions, if any.
                for (IBinder sessionToken : serviceState.sessionTokens) {
                    createSessionInternalLocked(serviceState.service, sessionToken, mUserId);
                }
            }
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            if (DEBUG) {
                Log.d(TAG, "onServiceDisconnected(name=" + name.getClassName() + ")");
            }
        }
    }

    private final class ServiceCallback extends ITvInputServiceCallback.Stub {
        private final int mUserId;

        ServiceCallback(int userId) {
            mUserId = userId;
        }

        @Override
        public void onAvailabilityChanged(ComponentName name, boolean isAvailable)
                throws RemoteException {
            if (DEBUG) {
                Log.d(TAG, "onAvailabilityChanged(name=" + name.getClassName() + ", isAvailable="
                        + isAvailable + ")");
            }
            synchronized (mLock) {
                ServiceState serviceState = getServiceStateLocked(name, mUserId);
                serviceState.available = isAvailable;
                for (IBinder iBinder : serviceState.clients) {
                    ITvInputClient client = ITvInputClient.Stub.asInterface(iBinder);
                    client.onAvailabilityChanged(name, isAvailable);
                }
            }
        }
    }
}