services/java/com/android/server/input/InputManagerService.java

/*
 * Copyright (C) 2010 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.input;

import com.android.internal.os.AtomicFile;
import com.android.internal.util.FastXmlSerializer;
import com.android.internal.util.XmlUtils;
import com.android.server.Watchdog;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlSerializer;

import android.Manifest;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.content.res.Resources.NotFoundException;
import android.content.res.TypedArray;
import android.content.res.XmlResourceParser;
import android.database.ContentObserver;
import android.hardware.input.IInputManager;
import android.hardware.input.IInputDevicesChangedListener;
import android.hardware.input.InputManager;
import android.hardware.input.KeyboardLayout;
import android.os.Binder;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.MessageQueue;
import android.os.Process;
import android.os.RemoteException;
import android.provider.Settings;
import android.provider.Settings.SettingNotFoundException;
import android.server.BluetoothService;
import android.util.Log;
import android.util.Slog;
import android.util.SparseArray;
import android.util.Xml;
import android.view.InputChannel;
import android.view.InputDevice;
import android.view.InputEvent;
import android.view.KeyEvent;
import android.view.PointerIcon;
import android.view.Surface;
import android.view.ViewConfiguration;
import android.view.WindowManagerPolicy;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileDescriptor;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

import libcore.io.IoUtils;
import libcore.io.Streams;
import libcore.util.Objects;

/*
 * Wraps the C++ InputManager and provides its callbacks.
 */
public class InputManagerService extends IInputManager.Stub implements Watchdog.Monitor {
    static final String TAG = "InputManager";
    static final boolean DEBUG = true;

    private static final String EXCLUDED_DEVICES_PATH = "etc/excluded-input-devices.xml";

    private static final int MSG_DELIVER_INPUT_DEVICES_CHANGED = 1;

    // Pointer to native input manager service object.
    private final int mPtr;

    private final Context mContext;
    private final Callbacks mCallbacks;
    private final InputManagerHandler mHandler;
    private boolean mSystemReady;
    private BluetoothService mBluetoothService;

    // Persistent data store.  Must be locked each time during use.
    private final PersistentDataStore mDataStore = new PersistentDataStore();

    // List of currently registered input devices changed listeners by process id.
    private Object mInputDevicesLock = new Object();
    private boolean mInputDevicesChangedPending; // guarded by mInputDevicesLock
    private InputDevice[] mInputDevices = new InputDevice[0];
    private final SparseArray<InputDevicesChangedListenerRecord> mInputDevicesChangedListeners =
            new SparseArray<InputDevicesChangedListenerRecord>(); // guarded by mInputDevicesLock
    private final ArrayList<InputDevicesChangedListenerRecord>
            mTempInputDevicesChangedListenersToNotify =
                    new ArrayList<InputDevicesChangedListenerRecord>(); // handler thread only

    // State for vibrator tokens.
    private Object mVibratorLock = new Object();
    private HashMap<IBinder, VibratorToken> mVibratorTokens =
            new HashMap<IBinder, VibratorToken>();
    private int mNextVibratorTokenValue;

    // State for the currently installed input filter.
    final Object mInputFilterLock = new Object();
    InputFilter mInputFilter; // guarded by mInputFilterLock
    InputFilterHost mInputFilterHost; // guarded by mInputFilterLock

    private static native int nativeInit(InputManagerService service,
            Context context, MessageQueue messageQueue);
    private static native void nativeStart(int ptr);
    private static native void nativeSetDisplaySize(int ptr, int displayId,
            int width, int height, int externalWidth, int externalHeight);
    private static native void nativeSetDisplayOrientation(int ptr, int displayId, int rotation);
    
    private static native int nativeGetScanCodeState(int ptr,
            int deviceId, int sourceMask, int scanCode);
    private static native int nativeGetKeyCodeState(int ptr,
            int deviceId, int sourceMask, int keyCode);
    private static native int nativeGetSwitchState(int ptr,
            int deviceId, int sourceMask, int sw);
    private static native boolean nativeHasKeys(int ptr,
            int deviceId, int sourceMask, int[] keyCodes, boolean[] keyExists);
    private static native void nativeRegisterInputChannel(int ptr, InputChannel inputChannel,
            InputWindowHandle inputWindowHandle, boolean monitor);
    private static native void nativeUnregisterInputChannel(int ptr, InputChannel inputChannel);
    private static native void nativeSetInputFilterEnabled(int ptr, boolean enable);
    private static native int nativeInjectInputEvent(int ptr, InputEvent event,
            int injectorPid, int injectorUid, int syncMode, int timeoutMillis,
            int policyFlags);
    private static native void nativeSetInputWindows(int ptr, InputWindowHandle[] windowHandles);
    private static native void nativeSetInputDispatchMode(int ptr, boolean enabled, boolean frozen);
    private static native void nativeSetSystemUiVisibility(int ptr, int visibility);
    private static native void nativeSetFocusedApplication(int ptr,
            InputApplicationHandle application);
    private static native void nativeGetInputConfiguration(int ptr, Configuration configuration);
    private static native boolean nativeTransferTouchFocus(int ptr,
            InputChannel fromChannel, InputChannel toChannel);
    private static native void nativeSetPointerSpeed(int ptr, int speed);
    private static native void nativeSetShowTouches(int ptr, boolean enabled);
    private static native void nativeVibrate(int ptr, int deviceId, long[] pattern,
            int repeat, int token);
    private static native void nativeCancelVibrate(int ptr, int deviceId, int token);
    private static native void nativeReloadKeyboardLayouts(int ptr);
    private static native void nativeReloadDeviceAliases(int ptr);
    private static native String nativeDump(int ptr);
    private static native void nativeMonitor(int ptr);

    // Input event injection constants defined in InputDispatcher.h.
    private static final int INPUT_EVENT_INJECTION_SUCCEEDED = 0;
    private static final int INPUT_EVENT_INJECTION_PERMISSION_DENIED = 1;
    private static final int INPUT_EVENT_INJECTION_FAILED = 2;
    private static final int INPUT_EVENT_INJECTION_TIMED_OUT = 3;

    // Maximum number of milliseconds to wait for input event injection.
    private static final int INJECTION_TIMEOUT_MILLIS = 30 * 1000;

    // Key states (may be returned by queries about the current state of a
    // particular key code, scan code or switch).
    
    /** The key state is unknown or the requested key itself is not supported. */
    public static final int KEY_STATE_UNKNOWN = -1;

    /** The key is up. /*/
    public static final int KEY_STATE_UP = 0;

    /** The key is down. */
    public static final int KEY_STATE_DOWN = 1;

    /** The key is down but is a virtual key press that is being emulated by the system. */
    public static final int KEY_STATE_VIRTUAL = 2;

    public InputManagerService(Context context, Callbacks callbacks) {
        this.mContext = context;
        this.mCallbacks = callbacks;
        this.mHandler = new InputManagerHandler();

        Slog.i(TAG, "Initializing input manager");
        mPtr = nativeInit(this, mContext, mHandler.getLooper().getQueue());
    }

    public void start() {
        Slog.i(TAG, "Starting input manager");
        nativeStart(mPtr);

        // Add ourself to the Watchdog monitors.
        Watchdog.getInstance().addMonitor(this);

        registerPointerSpeedSettingObserver();
        registerShowTouchesSettingObserver();

        updatePointerSpeedFromSettings();
        updateShowTouchesFromSettings();
    }

    public void systemReady(BluetoothService bluetoothService) {
        if (DEBUG) {
            Slog.d(TAG, "System ready.");
        }
        mBluetoothService = bluetoothService;
        mSystemReady = true;

        IntentFilter filter = new IntentFilter(Intent.ACTION_PACKAGE_ADDED);
        filter.addAction(Intent.ACTION_PACKAGE_REMOVED);
        filter.addAction(Intent.ACTION_PACKAGE_CHANGED);
        filter.addDataScheme("package");
        mContext.registerReceiver(new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                if (DEBUG) {
                    Slog.d(TAG, "Packages changed, reloading keyboard layouts.");
                }
                reloadKeyboardLayouts();
            }
        }, filter, null, mHandler);

        filter = new IntentFilter(BluetoothDevice.ACTION_ALIAS_CHANGED);
        mContext.registerReceiver(new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                if (DEBUG) {
                    Slog.d(TAG, "Bluetooth alias changed, reloading device names.");
                }
                reloadDeviceAliases();
            }
        }, filter, null, mHandler);

        reloadKeyboardLayouts();
        reloadDeviceAliases();
    }

    private void reloadKeyboardLayouts() {
        nativeReloadKeyboardLayouts(mPtr);
    }

    private void reloadDeviceAliases() {
        nativeReloadDeviceAliases(mPtr);
    }

    public void setDisplaySize(int displayId, int width, int height,
            int externalWidth, int externalHeight) {
        if (width <= 0 || height <= 0 || externalWidth <= 0 || externalHeight <= 0) {
            throw new IllegalArgumentException("Invalid display id or dimensions.");
        }
        
        if (DEBUG) {
            Slog.d(TAG, "Setting display #" + displayId + " size to " + width + "x" + height
                    + " external size " + externalWidth + "x" + externalHeight);
        }
        nativeSetDisplaySize(mPtr, displayId, width, height, externalWidth, externalHeight);
    }
    
    public void setDisplayOrientation(int displayId, int rotation) {
        if (rotation < Surface.ROTATION_0 || rotation > Surface.ROTATION_270) {
            throw new IllegalArgumentException("Invalid rotation.");
        }
        
        if (DEBUG) {
            Slog.d(TAG, "Setting display #" + displayId + " orientation to " + rotation);
        }
        nativeSetDisplayOrientation(mPtr, displayId, rotation);
    }
    
    public void getInputConfiguration(Configuration config) {
        if (config == null) {
            throw new IllegalArgumentException("config must not be null.");
        }
        
        nativeGetInputConfiguration(mPtr, config);
    }

    /**
     * Gets the current state of a key or button by key code.
     * @param deviceId The input device id, or -1 to consult all devices.
     * @param sourceMask The input sources to consult, or {@link InputDevice#SOURCE_ANY} to
     * consider all input sources.  An input device is consulted if at least one of its
     * non-class input source bits matches the specified source mask.
     * @param keyCode The key code to check.
     * @return The key state.
     */
    public int getKeyCodeState(int deviceId, int sourceMask, int keyCode) {
        return nativeGetKeyCodeState(mPtr, deviceId, sourceMask, keyCode);
    }
    
    /**
     * Gets the current state of a key or button by scan code.
     * @param deviceId The input device id, or -1 to consult all devices.
     * @param sourceMask The input sources to consult, or {@link InputDevice#SOURCE_ANY} to
     * consider all input sources.  An input device is consulted if at least one of its
     * non-class input source bits matches the specified source mask.
     * @param scanCode The scan code to check.
     * @return The key state.
     */
    public int getScanCodeState(int deviceId, int sourceMask, int scanCode) {
        return nativeGetScanCodeState(mPtr, deviceId, sourceMask, scanCode);
    }
    
    /**
     * Gets the current state of a switch by switch code.
     * @param deviceId The input device id, or -1 to consult all devices.
     * @param sourceMask The input sources to consult, or {@link InputDevice#SOURCE_ANY} to
     * consider all input sources.  An input device is consulted if at least one of its
     * non-class input source bits matches the specified source mask.
     * @param switchCode The switch code to check.
     * @return The switch state.
     */
    public int getSwitchState(int deviceId, int sourceMask, int switchCode) {
        return nativeGetSwitchState(mPtr, deviceId, sourceMask, switchCode);
    }

    /**
     * Determines whether the specified key codes are supported by a particular device.
     * @param deviceId The input device id, or -1 to consult all devices.
     * @param sourceMask The input sources to consult, or {@link InputDevice#SOURCE_ANY} to
     * consider all input sources.  An input device is consulted if at least one of its
     * non-class input source bits matches the specified source mask.
     * @param keyCodes The array of key codes to check.
     * @param keyExists An array at least as large as keyCodes whose entries will be set
     * to true or false based on the presence or absence of support for the corresponding
     * key codes.
     * @return True if the lookup was successful, false otherwise.
     */
    @Override // Binder call
    public boolean hasKeys(int deviceId, int sourceMask, int[] keyCodes, boolean[] keyExists) {
        if (keyCodes == null) {
            throw new IllegalArgumentException("keyCodes must not be null.");
        }
        if (keyExists == null || keyExists.length < keyCodes.length) {
            throw new IllegalArgumentException("keyExists must not be null and must be at "
                    + "least as large as keyCodes.");
        }
        
        return nativeHasKeys(mPtr, deviceId, sourceMask, keyCodes, keyExists);
    }
    
    /**
     * Creates an input channel that will receive all input from the input dispatcher.
     * @param inputChannelName The input channel name.
     * @return The input channel.
     */
    public InputChannel monitorInput(String inputChannelName) {
        if (inputChannelName == null) {
            throw new IllegalArgumentException("inputChannelName must not be null.");
        }
        
        InputChannel[] inputChannels = InputChannel.openInputChannelPair(inputChannelName);
        nativeRegisterInputChannel(mPtr, inputChannels[0], null, true);
        inputChannels[0].dispose(); // don't need to retain the Java object reference
        return inputChannels[1];
    }

    /**
     * Registers an input channel so that it can be used as an input event target.
     * @param inputChannel The input channel to register.
     * @param inputWindowHandle The handle of the input window associated with the
     * input channel, or null if none.
     */
    public void registerInputChannel(InputChannel inputChannel,
            InputWindowHandle inputWindowHandle) {
        if (inputChannel == null) {
            throw new IllegalArgumentException("inputChannel must not be null.");
        }
        
        nativeRegisterInputChannel(mPtr, inputChannel, inputWindowHandle, false);
    }
    
    /**
     * Unregisters an input channel.
     * @param inputChannel The input channel to unregister.
     */
    public void unregisterInputChannel(InputChannel inputChannel) {
        if (inputChannel == null) {
            throw new IllegalArgumentException("inputChannel must not be null.");
        }
        
        nativeUnregisterInputChannel(mPtr, inputChannel);
    }

    /**
     * Sets an input filter that will receive all input events before they are dispatched.
     * The input filter may then reinterpret input events or inject new ones.
     *
     * To ensure consistency, the input dispatcher automatically drops all events
     * in progress whenever an input filter is installed or uninstalled.  After an input
     * filter is uninstalled, it can no longer send input events unless it is reinstalled.
     * Any events it attempts to send after it has been uninstalled will be dropped.
     *
     * @param filter The input filter, or null to remove the current filter.
     */
    public void setInputFilter(InputFilter filter) {
        synchronized (mInputFilterLock) {
            final InputFilter oldFilter = mInputFilter;
            if (oldFilter == filter) {
                return; // nothing to do
            }

            if (oldFilter != null) {
                mInputFilter = null;
                mInputFilterHost.disconnectLocked();
                mInputFilterHost = null;
                oldFilter.uninstall();
            }

            if (filter != null) {
                mInputFilter = filter;
                mInputFilterHost = new InputFilterHost();
                filter.install(mInputFilterHost);
            }

            nativeSetInputFilterEnabled(mPtr, filter != null);
        }
    }

    @Override // Binder call
    public boolean injectInputEvent(InputEvent event, int mode) {
        if (event == null) {
            throw new IllegalArgumentException("event must not be null");
        }
        if (mode != InputManager.INJECT_INPUT_EVENT_MODE_ASYNC
                && mode != InputManager.INJECT_INPUT_EVENT_MODE_WAIT_FOR_FINISH
                && mode != InputManager.INJECT_INPUT_EVENT_MODE_WAIT_FOR_RESULT) {
            throw new IllegalArgumentException("mode is invalid");
        }

        final int pid = Binder.getCallingPid();
        final int uid = Binder.getCallingUid();
        final long ident = Binder.clearCallingIdentity();
        final int result;
        try {
            result = nativeInjectInputEvent(mPtr, event, pid, uid, mode,
                    INJECTION_TIMEOUT_MILLIS, WindowManagerPolicy.FLAG_DISABLE_KEY_REPEAT);
        } finally {
            Binder.restoreCallingIdentity(ident);
        }
        switch (result) {
            case INPUT_EVENT_INJECTION_PERMISSION_DENIED:
                Slog.w(TAG, "Input event injection from pid " + pid + " permission denied.");
                throw new SecurityException(
                        "Injecting to another application requires INJECT_EVENTS permission");
            case INPUT_EVENT_INJECTION_SUCCEEDED:
                return true;
            case INPUT_EVENT_INJECTION_TIMED_OUT:
                Slog.w(TAG, "Input event injection from pid " + pid + " timed out.");
                return false;
            case INPUT_EVENT_INJECTION_FAILED:
            default:
                Slog.w(TAG, "Input event injection from pid " + pid + " failed.");
                return false;
        }
    }

    /**
     * Gets information about the input device with the specified id.
     * @param id The device id.
     * @return The input device or null if not found.
     */
    @Override // Binder call
    public InputDevice getInputDevice(int deviceId) {
        synchronized (mInputDevicesLock) {
            final int count = mInputDevices.length;
            for (int i = 0; i < count; i++) {
                final InputDevice inputDevice = mInputDevices[i];
                if (inputDevice.getId() == deviceId) {
                    return inputDevice;
                }
            }
        }
        return null;
    }

    /**
     * Gets the ids of all input devices in the system.
     * @return The input device ids.
     */
    @Override // Binder call
    public int[] getInputDeviceIds() {
        synchronized (mInputDevicesLock) {
            final int count = mInputDevices.length;
            int[] ids = new int[count];
            for (int i = 0; i < count; i++) {
                ids[i] = mInputDevices[i].getId();
            }
            return ids;
        }
    }

    @Override // Binder call
    public void registerInputDevicesChangedListener(IInputDevicesChangedListener listener) {
        if (listener == null) {
            throw new IllegalArgumentException("listener must not be null");
        }

        synchronized (mInputDevicesLock) {
            int callingPid = Binder.getCallingPid();
            if (mInputDevicesChangedListeners.get(callingPid) != null) {
                throw new SecurityException("The calling process has already "
                        + "registered an InputDevicesChangedListener.");
            }

            InputDevicesChangedListenerRecord record =
                    new InputDevicesChangedListenerRecord(callingPid, listener);
            try {
                IBinder binder = listener.asBinder();
                binder.linkToDeath(record, 0);
            } catch (RemoteException ex) {
                // give up
                throw new RuntimeException(ex);
            }

            mInputDevicesChangedListeners.put(callingPid, record);
        }
    }

    private void onInputDevicesChangedListenerDied(int pid) {
        synchronized (mInputDevicesLock) {
            mInputDevicesChangedListeners.remove(pid);
        }
    }

    // Must be called on handler.
    private void deliverInputDevicesChanged() {
        mTempInputDevicesChangedListenersToNotify.clear();

        final int numListeners;
        final int[] deviceIdAndGeneration;
        synchronized (mInputDevicesLock) {
            if (!mInputDevicesChangedPending) {
                return;
            }
            mInputDevicesChangedPending = false;

            numListeners = mInputDevicesChangedListeners.size();
            for (int i = 0; i < numListeners; i++) {
                mTempInputDevicesChangedListenersToNotify.add(
                        mInputDevicesChangedListeners.valueAt(i));
            }

            final int numDevices = mInputDevices.length;
            deviceIdAndGeneration = new int[numDevices * 2];
            for (int i = 0; i < numDevices; i++) {
                final InputDevice inputDevice = mInputDevices[i];
                deviceIdAndGeneration[i * 2] = inputDevice.getId();
                deviceIdAndGeneration[i * 2 + 1] = inputDevice.getGeneration();
            }
        }

        for (int i = 0; i < numListeners; i++) {
            mTempInputDevicesChangedListenersToNotify.get(i).notifyInputDevicesChanged(
                    deviceIdAndGeneration);
        }
    }

    @Override // Binder call
    public KeyboardLayout[] getKeyboardLayouts() {
        final ArrayList<KeyboardLayout> list = new ArrayList<KeyboardLayout>();
        visitAllKeyboardLayouts(new KeyboardLayoutVisitor() {
            @Override
            public void visitKeyboardLayout(Resources resources,
                    String descriptor, String label, int kcmResId) {
                list.add(new KeyboardLayout(descriptor, label));
            }
        });
        return list.toArray(new KeyboardLayout[list.size()]);
    }

    @Override // Binder call
    public KeyboardLayout getKeyboardLayout(String keyboardLayoutDescriptor) {
        if (keyboardLayoutDescriptor == null) {
            throw new IllegalArgumentException("keyboardLayoutDescriptor must not be null");
        }

        final KeyboardLayout[] result = new KeyboardLayout[1];
        visitKeyboardLayout(keyboardLayoutDescriptor, new KeyboardLayoutVisitor() {
            @Override
            public void visitKeyboardLayout(Resources resources,
                    String descriptor, String label, int kcmResId) {
                result[0] = new KeyboardLayout(descriptor, label);
            }
        });
        if (result[0] == null) {
            Log.w(TAG, "Could not get keyboard layout with descriptor '"
                    + keyboardLayoutDescriptor + "'.");
        }
        return result[0];
    }

    private void visitAllKeyboardLayouts(KeyboardLayoutVisitor visitor) {
        final PackageManager pm = mContext.getPackageManager();
        Intent intent = new Intent(InputManager.ACTION_QUERY_KEYBOARD_LAYOUTS);
        for (ResolveInfo resolveInfo : pm.queryBroadcastReceivers(intent,
                PackageManager.GET_META_DATA)) {
            visitKeyboardLayoutsInPackage(pm, resolveInfo.activityInfo, null, visitor);
        }
    }

    private void visitKeyboardLayout(String keyboardLayoutDescriptor,
            KeyboardLayoutVisitor visitor) {
        KeyboardLayoutDescriptor d = KeyboardLayoutDescriptor.parse(keyboardLayoutDescriptor);
        if (d != null) {
            final PackageManager pm = mContext.getPackageManager();
            try {
                ActivityInfo receiver = pm.getReceiverInfo(
                        new ComponentName(d.packageName, d.receiverName),
                        PackageManager.GET_META_DATA);
                visitKeyboardLayoutsInPackage(pm, receiver, d.keyboardLayoutName, visitor);
            } catch (NameNotFoundException ex) {
            }
        }
    }

    private void visitKeyboardLayoutsInPackage(PackageManager pm, ActivityInfo receiver,
            String keyboardName, KeyboardLayoutVisitor visitor) {
        Bundle metaData = receiver.metaData;
        if (metaData == null) {
            return;
        }

        int configResId = metaData.getInt(InputManager.META_DATA_KEYBOARD_LAYOUTS);
        if (configResId == 0) {
            Log.w(TAG, "Missing meta-data '" + InputManager.META_DATA_KEYBOARD_LAYOUTS
                    + "' on receiver " + receiver.packageName + "/" + receiver.name);
            return;
        }

        try {
            Resources resources = pm.getResourcesForApplication(receiver.applicationInfo);
            XmlResourceParser parser = resources.getXml(configResId);
            try {
                XmlUtils.beginDocument(parser, "keyboard-layouts");

                for (;;) {
                    XmlUtils.nextElement(parser);
                    String element = parser.getName();
                    if (element == null) {
                        break;
                    }
                    if (element.equals("keyboard-layout")) {
                        TypedArray a = resources.obtainAttributes(
                                parser, com.android.internal.R.styleable.KeyboardLayout);
                        try {
                            String name = a.getString(
                                    com.android.internal.R.styleable.KeyboardLayout_name);
                            String label = a.getString(
                                    com.android.internal.R.styleable.KeyboardLayout_label);
                            int kcmResId = a.getResourceId(
                                     com.android.internal.R.styleable.KeyboardLayout_kcm, 0);
                            if (name == null || label == null || kcmResId == 0) {
                                Log.w(TAG, "Missing required 'name', 'label' or 'kcm' "
                                        + "attributes in keyboard layout "
                                        + "resource from receiver "
                                        + receiver.packageName + "/" + receiver.name);
                            } else {
                                String descriptor = KeyboardLayoutDescriptor.format(
                                        receiver.packageName, receiver.name, name);
                                if (keyboardName == null || name.equals(keyboardName)) {
                                    visitor.visitKeyboardLayout(resources, descriptor,
                                            label, kcmResId);
                                }
                            }
                        } finally {
                            a.recycle();
                        }
                    } else {
                        Log.w(TAG, "Skipping unrecognized element '" + element
                                + "' in keyboard layout resource from receiver "
                                + receiver.packageName + "/" + receiver.name);
                    }
                }
            } finally {
                parser.close();
            }
        } catch (Exception ex) {
            Log.w(TAG, "Could not parse keyboard layout resource from receiver "
                    + receiver.packageName + "/" + receiver.name, ex);
        }
    }

    @Override // Binder call
    public String getKeyboardLayoutForInputDevice(String inputDeviceDescriptor) {
        if (inputDeviceDescriptor == null) {
            throw new IllegalArgumentException("inputDeviceDescriptor must not be null");
        }

        synchronized (mDataStore) {
            return mDataStore.getKeyboardLayout(inputDeviceDescriptor);
        }
    }

    @Override // Binder call
    public void setKeyboardLayoutForInputDevice(String inputDeviceDescriptor,
            String keyboardLayoutDescriptor) {
        if (!checkCallingPermission(android.Manifest.permission.SET_KEYBOARD_LAYOUT,
                "setKeyboardLayoutForInputDevice()")) {
            throw new SecurityException("Requires SET_KEYBOARD_LAYOUT permission");
        }

        if (inputDeviceDescriptor == null) {
            throw new IllegalArgumentException("inputDeviceDescriptor must not be null");
        }

        final boolean changed;
        synchronized (mDataStore) {
            try {
                changed = mDataStore.setKeyboardLayout(
                        inputDeviceDescriptor, keyboardLayoutDescriptor);
            } finally {
                mDataStore.saveIfNeeded();
            }
        }

        if (changed) {
            if (DEBUG) {
                Slog.d(TAG, "Keyboard layout changed, reloading keyboard layouts.");
            }
            reloadKeyboardLayouts();
        }
    }

    public void setInputWindows(InputWindowHandle[] windowHandles) {
        nativeSetInputWindows(mPtr, windowHandles);
    }
    
    public void setFocusedApplication(InputApplicationHandle application) {
        nativeSetFocusedApplication(mPtr, application);
    }
    
    public void setInputDispatchMode(boolean enabled, boolean frozen) {
        nativeSetInputDispatchMode(mPtr, enabled, frozen);
    }

    public void setSystemUiVisibility(int visibility) {
        nativeSetSystemUiVisibility(mPtr, visibility);
    }

    /**
     * Atomically transfers touch focus from one window to another as identified by
     * their input channels.  It is possible for multiple windows to have
     * touch focus if they support split touch dispatch
     * {@link android.view.WindowManager.LayoutParams#FLAG_SPLIT_TOUCH} but this
     * method only transfers touch focus of the specified window without affecting
     * other windows that may also have touch focus at the same time.
     * @param fromChannel The channel of a window that currently has touch focus.
     * @param toChannel The channel of the window that should receive touch focus in
     * place of the first.
     * @return True if the transfer was successful.  False if the window with the
     * specified channel did not actually have touch focus at the time of the request.
     */
    public boolean transferTouchFocus(InputChannel fromChannel, InputChannel toChannel) {
        if (fromChannel == null) {
            throw new IllegalArgumentException("fromChannel must not be null.");
        }
        if (toChannel == null) {
            throw new IllegalArgumentException("toChannel must not be null.");
        }
        return nativeTransferTouchFocus(mPtr, fromChannel, toChannel);
    }

    @Override // Binder call
    public void tryPointerSpeed(int speed) {
        if (!checkCallingPermission(android.Manifest.permission.SET_POINTER_SPEED,
                "tryPointerSpeed()")) {
            throw new SecurityException("Requires SET_POINTER_SPEED permission");
        }

        if (speed < InputManager.MIN_POINTER_SPEED || speed > InputManager.MAX_POINTER_SPEED) {
            throw new IllegalArgumentException("speed out of range");
        }

        setPointerSpeedUnchecked(speed);
    }

    public void updatePointerSpeedFromSettings() {
        int speed = getPointerSpeedSetting();
        setPointerSpeedUnchecked(speed);
    }

    private void setPointerSpeedUnchecked(int speed) {
        speed = Math.min(Math.max(speed, InputManager.MIN_POINTER_SPEED),
                InputManager.MAX_POINTER_SPEED);
        nativeSetPointerSpeed(mPtr, speed);
    }

    private void registerPointerSpeedSettingObserver() {
        mContext.getContentResolver().registerContentObserver(
                Settings.System.getUriFor(Settings.System.POINTER_SPEED), true,
                new ContentObserver(mHandler) {
                    @Override
                    public void onChange(boolean selfChange) {
                        updatePointerSpeedFromSettings();
                    }
                });
    }

    private int getPointerSpeedSetting() {
        int speed = InputManager.DEFAULT_POINTER_SPEED;
        try {
            speed = Settings.System.getInt(mContext.getContentResolver(),
                    Settings.System.POINTER_SPEED);
        } catch (SettingNotFoundException snfe) {
        }
        return speed;
    }

    public void updateShowTouchesFromSettings() {
        int setting = getShowTouchesSetting(0);
        nativeSetShowTouches(mPtr, setting != 0);
    }

    private void registerShowTouchesSettingObserver() {
        mContext.getContentResolver().registerContentObserver(
                Settings.System.getUriFor(Settings.System.SHOW_TOUCHES), true,
                new ContentObserver(mHandler) {
                    @Override
                    public void onChange(boolean selfChange) {
                        updateShowTouchesFromSettings();
                    }
                });
    }

    private int getShowTouchesSetting(int defaultValue) {
        int result = defaultValue;
        try {
            result = Settings.System.getInt(mContext.getContentResolver(),
                    Settings.System.SHOW_TOUCHES);
        } catch (SettingNotFoundException snfe) {
        }
        return result;
    }

    // Binder call
    @Override
    public void vibrate(int deviceId, long[] pattern, int repeat, IBinder token) {
        if (repeat >= pattern.length) {
            throw new ArrayIndexOutOfBoundsException();
        }

        VibratorToken v;
        synchronized (mVibratorLock) {
            v = mVibratorTokens.get(token);
            if (v == null) {
                v = new VibratorToken(deviceId, token, mNextVibratorTokenValue++);
                try {
                    token.linkToDeath(v, 0);
                } catch (RemoteException ex) {
                    // give up
                    throw new RuntimeException(ex);
                }
                mVibratorTokens.put(token, v);
            }
        }

        synchronized (v) {
            v.mVibrating = true;
            nativeVibrate(mPtr, deviceId, pattern, repeat, v.mTokenValue);
        }
    }

    // Binder call
    @Override
    public void cancelVibrate(int deviceId, IBinder token) {
        VibratorToken v;
        synchronized (mVibratorLock) {
            v = mVibratorTokens.get(token);
            if (v == null || v.mDeviceId != deviceId) {
                return; // nothing to cancel
            }
        }

        cancelVibrateIfNeeded(v);
    }

    void onVibratorTokenDied(VibratorToken v) {
        synchronized (mVibratorLock) {
            mVibratorTokens.remove(v.mToken);
        }

        cancelVibrateIfNeeded(v);
    }

    private void cancelVibrateIfNeeded(VibratorToken v) {
        synchronized (v) {
            if (v.mVibrating) {
                nativeCancelVibrate(mPtr, v.mDeviceId, v.mTokenValue);
                v.mVibrating = false;
            }
        }
    }

    @Override
    public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
        if (mContext.checkCallingOrSelfPermission(Manifest.permission.DUMP)
                != PackageManager.PERMISSION_GRANTED) {
            pw.println("Permission Denial: can't dump InputManager from from pid="
                    + Binder.getCallingPid()
                    + ", uid=" + Binder.getCallingUid());
            return;
        }

        pw.println("INPUT MANAGER (dumpsys input)\n");
        String dumpStr = nativeDump(mPtr);
        if (dumpStr != null) {
            pw.println(dumpStr);
        }
    }

    private boolean checkCallingPermission(String permission, String func) {
        // Quick check: if the calling permission is me, it's all okay.
        if (Binder.getCallingPid() == Process.myPid()) {
            return true;
        }

        if (mContext.checkCallingPermission(permission) == PackageManager.PERMISSION_GRANTED) {
            return true;
        }
        String msg = "Permission Denial: " + func + " from pid="
                + Binder.getCallingPid()
                + ", uid=" + Binder.getCallingUid()
                + " requires " + permission;
        Slog.w(TAG, msg);
        return false;
    }

    // Called by the heartbeat to ensure locks are not held indefinitely (for deadlock detection).
    public void monitor() {
        synchronized (mInputFilterLock) { }
        nativeMonitor(mPtr);
    }

    // Native callback.
    private void notifyConfigurationChanged(long whenNanos) {
        mCallbacks.notifyConfigurationChanged();
    }

    // Native callback.
    private void notifyInputDevicesChanged(InputDevice[] inputDevices) {
        synchronized (mInputDevicesLock) {
            mInputDevices = inputDevices;

            if (!mInputDevicesChangedPending) {
                mInputDevicesChangedPending = true;
                mHandler.sendEmptyMessage(MSG_DELIVER_INPUT_DEVICES_CHANGED);
            }
        }
    }

    // Native callback.
    private void notifyLidSwitchChanged(long whenNanos, boolean lidOpen) {
        mCallbacks.notifyLidSwitchChanged(whenNanos, lidOpen);
    }

    // Native callback.
    private void notifyInputChannelBroken(InputWindowHandle inputWindowHandle) {
        mCallbacks.notifyInputChannelBroken(inputWindowHandle);
    }

    // Native callback.
    private long notifyANR(InputApplicationHandle inputApplicationHandle,
            InputWindowHandle inputWindowHandle) {
        return mCallbacks.notifyANR(inputApplicationHandle, inputWindowHandle);
    }

    // Native callback.
    final boolean filterInputEvent(InputEvent event, int policyFlags) {
        synchronized (mInputFilterLock) {
            if (mInputFilter != null) {
                mInputFilter.filterInputEvent(event, policyFlags);
                return false;
            }
        }
        event.recycle();
        return true;
    }

    // Native callback.
    private int interceptKeyBeforeQueueing(KeyEvent event, int policyFlags, boolean isScreenOn) {
        return mCallbacks.interceptKeyBeforeQueueing(
                event, policyFlags, isScreenOn);
    }

    // Native callback.
    private int interceptMotionBeforeQueueingWhenScreenOff(int policyFlags) {
        return mCallbacks.interceptMotionBeforeQueueingWhenScreenOff(policyFlags);
    }

    // Native callback.
    private long interceptKeyBeforeDispatching(InputWindowHandle focus,
            KeyEvent event, int policyFlags) {
        return mCallbacks.interceptKeyBeforeDispatching(focus, event, policyFlags);
    }

    // Native callback.
    private KeyEvent dispatchUnhandledKey(InputWindowHandle focus,
            KeyEvent event, int policyFlags) {
        return mCallbacks.dispatchUnhandledKey(focus, event, policyFlags);
    }

    // Native callback.
    private boolean checkInjectEventsPermission(int injectorPid, int injectorUid) {
        return mContext.checkPermission(android.Manifest.permission.INJECT_EVENTS,
                injectorPid, injectorUid) == PackageManager.PERMISSION_GRANTED;
    }

    // Native callback.
    private int getVirtualKeyQuietTimeMillis() {
        return mContext.getResources().getInteger(
                com.android.internal.R.integer.config_virtualKeyQuietTimeMillis);
    }

    // Native callback.
    private String[] getExcludedDeviceNames() {
        ArrayList<String> names = new ArrayList<String>();

        // Read partner-provided list of excluded input devices
        XmlPullParser parser = null;
        // Environment.getRootDirectory() is a fancy way of saying ANDROID_ROOT or "/system".
        File confFile = new File(Environment.getRootDirectory(), EXCLUDED_DEVICES_PATH);
        FileReader confreader = null;
        try {
            confreader = new FileReader(confFile);
            parser = Xml.newPullParser();
            parser.setInput(confreader);
            XmlUtils.beginDocument(parser, "devices");

            while (true) {
                XmlUtils.nextElement(parser);
                if (!"device".equals(parser.getName())) {
                    break;
                }
                String name = parser.getAttributeValue(null, "name");
                if (name != null) {
                    names.add(name);
                }
            }
        } catch (FileNotFoundException e) {
            // It's ok if the file does not exist.
        } catch (Exception e) {
            Slog.e(TAG, "Exception while parsing '" + confFile.getAbsolutePath() + "'", e);
        } finally {
            try { if (confreader != null) confreader.close(); } catch (IOException e) { }
        }

        return names.toArray(new String[names.size()]);
    }

    // Native callback.
    private int getKeyRepeatTimeout() {
        return ViewConfiguration.getKeyRepeatTimeout();
    }

    // Native callback.
    private int getKeyRepeatDelay() {
        return ViewConfiguration.getKeyRepeatDelay();
    }

    // Native callback.
    private int getHoverTapTimeout() {
        return ViewConfiguration.getHoverTapTimeout();
    }

    // Native callback.
    private int getHoverTapSlop() {
        return ViewConfiguration.getHoverTapSlop();
    }

    // Native callback.
    private int getDoubleTapTimeout() {
        return ViewConfiguration.getDoubleTapTimeout();
    }

    // Native callback.
    private int getLongPressTimeout() {
        return ViewConfiguration.getLongPressTimeout();
    }

    // Native callback.
    private int getPointerLayer() {
        return mCallbacks.getPointerLayer();
    }

    // Native callback.
    private PointerIcon getPointerIcon() {
        return PointerIcon.getDefaultIcon(mContext);
    }

    // Native callback.
    private String[] getKeyboardLayoutOverlay(String inputDeviceDescriptor) {
        if (!mSystemReady) {
            return null;
        }

        String keyboardLayoutDescriptor = getKeyboardLayoutForInputDevice(inputDeviceDescriptor);
        if (keyboardLayoutDescriptor == null) {
            return null;
        }

        final String[] result = new String[2];
        visitKeyboardLayout(keyboardLayoutDescriptor, new KeyboardLayoutVisitor() {
            @Override
            public void visitKeyboardLayout(Resources resources,
                    String descriptor, String label, int kcmResId) {
                try {
                    result[0] = descriptor;
                    result[1] = Streams.readFully(new InputStreamReader(
                            resources.openRawResource(kcmResId)));
                } catch (IOException ex) {
                } catch (NotFoundException ex) {
                }
            }
        });
        if (result[0] == null) {
            Log.w(TAG, "Could not get keyboard layout with descriptor '"
                    + keyboardLayoutDescriptor + "'.");
            return null;
        }
        return result;
    }

    // Native callback.
    private String getDeviceAlias(String uniqueId) {
        if (mBluetoothService != null &&
                BluetoothAdapter.checkBluetoothAddress(uniqueId)) {
            return mBluetoothService.getRemoteAlias(uniqueId);
        }
        return null;
    }


    /**
     * Callback interface implemented by the Window Manager.
     */
    public interface Callbacks {
        public void notifyConfigurationChanged();

        public void notifyLidSwitchChanged(long whenNanos, boolean lidOpen);

        public void notifyInputChannelBroken(InputWindowHandle inputWindowHandle);

        public long notifyANR(InputApplicationHandle inputApplicationHandle,
                InputWindowHandle inputWindowHandle);

        public int interceptKeyBeforeQueueing(KeyEvent event, int policyFlags, boolean isScreenOn);

        public int interceptMotionBeforeQueueingWhenScreenOff(int policyFlags);

        public long interceptKeyBeforeDispatching(InputWindowHandle focus,
                KeyEvent event, int policyFlags);

        public KeyEvent dispatchUnhandledKey(InputWindowHandle focus,
                KeyEvent event, int policyFlags);

        public int getPointerLayer();
    }

    /**
     * Private handler for the input manager.
     */
    private final class InputManagerHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case MSG_DELIVER_INPUT_DEVICES_CHANGED:
                    deliverInputDevicesChanged();
                    break;
            }
        }
    }

    /**
     * Hosting interface for input filters to call back into the input manager.
     */
    private final class InputFilterHost implements InputFilter.Host {
        private boolean mDisconnected;

        public void disconnectLocked() {
            mDisconnected = true;
        }

        public void sendInputEvent(InputEvent event, int policyFlags) {
            if (event == null) {
                throw new IllegalArgumentException("event must not be null");
            }

            synchronized (mInputFilterLock) {
                if (!mDisconnected) {
                    nativeInjectInputEvent(mPtr, event, 0, 0,
                            InputManager.INJECT_INPUT_EVENT_MODE_ASYNC, 0,
                            policyFlags | WindowManagerPolicy.FLAG_FILTERED);
                }
            }
        }
    }

    private static final class KeyboardLayoutDescriptor {
        public String packageName;
        public String receiverName;
        public String keyboardLayoutName;

        public static String format(String packageName,
                String receiverName, String keyboardName) {
            return packageName + "/" + receiverName + "/" + keyboardName;
        }

        public static KeyboardLayoutDescriptor parse(String descriptor) {
            int pos = descriptor.indexOf('/');
            if (pos < 0 || pos + 1 == descriptor.length()) {
                return null;
            }
            int pos2 = descriptor.indexOf('/', pos + 1);
            if (pos2 < pos + 2 || pos2 + 1 == descriptor.length()) {
                return null;
            }

            KeyboardLayoutDescriptor result = new KeyboardLayoutDescriptor();
            result.packageName = descriptor.substring(0, pos);
            result.receiverName = descriptor.substring(pos + 1, pos2);
            result.keyboardLayoutName = descriptor.substring(pos2 + 1);
            return result;
        }
    }

    private interface KeyboardLayoutVisitor {
        void visitKeyboardLayout(Resources resources,
                String descriptor, String label, int kcmResId);
    }

    private final class InputDevicesChangedListenerRecord implements DeathRecipient {
        private final int mPid;
        private final IInputDevicesChangedListener mListener;

        public InputDevicesChangedListenerRecord(int pid, IInputDevicesChangedListener listener) {
            mPid = pid;
            mListener = listener;
        }

        @Override
        public void binderDied() {
            if (DEBUG) {
                Slog.d(TAG, "Input devices changed listener for pid " + mPid + " died.");
            }
            onInputDevicesChangedListenerDied(mPid);
        }

        public void notifyInputDevicesChanged(int[] info) {
            try {
                mListener.onInputDevicesChanged(info);
            } catch (RemoteException ex) {
                Slog.w(TAG, "Failed to notify process "
                        + mPid + " that input devices changed, assuming it died.", ex);
                binderDied();
            }
        }
    }

    private final class VibratorToken implements DeathRecipient {
        public final int mDeviceId;
        public final IBinder mToken;
        public final int mTokenValue;

        public boolean mVibrating;

        public VibratorToken(int deviceId, IBinder token, int tokenValue) {
            mDeviceId = deviceId;
            mToken = token;
            mTokenValue = tokenValue;
        }

        @Override
        public void binderDied() {
            if (DEBUG) {
                Slog.d(TAG, "Vibrator token died.");
            }
            onVibratorTokenDied(this);
        }
    }

    /**
     * Manages persistent state recorded by the input manager service as an XML file.
     * Caller must acquire lock on the data store before accessing it.
     *
     * File format:
     * <code>
     * &lt;input-mananger-state>
     *   &lt;input-devices>
     *     &lt;input-device descriptor="xxxxx" keyboard-layout="yyyyy" />
     *   &gt;input-devices>
     * &gt;/input-manager-state>
     * </code>
     */
    private static final class PersistentDataStore {
        // Input device state by descriptor.
        private final HashMap<String, InputDeviceState> mInputDevices =
                new HashMap<String, InputDeviceState>();
        private final AtomicFile mAtomicFile;

        // True if the data has been loaded.
        private boolean mLoaded;

        // True if there are changes to be saved.
        private boolean mDirty;

        public PersistentDataStore() {
            mAtomicFile = new AtomicFile(new File("/data/system/input-manager-state.xml"));
        }

        public void saveIfNeeded() {
            if (mDirty) {
                save();
                mDirty = false;
            }
        }

        public String getKeyboardLayout(String inputDeviceDescriptor) {
            InputDeviceState state = getInputDeviceState(inputDeviceDescriptor, false);
            return state != null ? state.keyboardLayoutDescriptor : null;
        }

        public boolean setKeyboardLayout(String inputDeviceDescriptor,
                String keyboardLayoutDescriptor) {
            InputDeviceState state = getInputDeviceState(inputDeviceDescriptor, true);
            if (!Objects.equal(state.keyboardLayoutDescriptor, keyboardLayoutDescriptor)) {
                state.keyboardLayoutDescriptor = keyboardLayoutDescriptor;
                setDirty();
                return true;
            }
            return false;
        }

        private InputDeviceState getInputDeviceState(String inputDeviceDescriptor,
                boolean createIfAbsent) {
            loadIfNeeded();
            InputDeviceState state = mInputDevices.get(inputDeviceDescriptor);
            if (state == null && createIfAbsent) {
                state = new InputDeviceState();
                mInputDevices.put(inputDeviceDescriptor, state);
                setDirty();
            }
            return state;
        }

        private void loadIfNeeded() {
            if (!mLoaded) {
                load();
                mLoaded = true;
            }
        }

        private void setDirty() {
            mDirty = true;
        }

        private void clearState() {
            mInputDevices.clear();
        }

        private void load() {
            clearState();

            final InputStream is;
            try {
                is = mAtomicFile.openRead();
            } catch (FileNotFoundException ex) {
                return;
            }

            XmlPullParser parser;
            try {
                parser = Xml.newPullParser();
                parser.setInput(new BufferedInputStream(is), null);
                loadFromXml(parser);
            } catch (IOException ex) {
                Slog.w(TAG, "Failed to load input manager persistent store data.", ex);
                clearState();
            } catch (XmlPullParserException ex) {
                Slog.w(TAG, "Failed to load input manager persistent store data.", ex);
                clearState();
            } finally {
                IoUtils.closeQuietly(is);
            }
        }

        private void save() {
            final FileOutputStream os;
            try {
                os = mAtomicFile.startWrite();
                boolean success = false;
                try {
                    XmlSerializer serializer = new FastXmlSerializer();
                    serializer.setOutput(new BufferedOutputStream(os), "utf-8");
                    saveToXml(serializer);
                    serializer.flush();
                    success = true;
                } finally {
                    if (success) {
                        mAtomicFile.finishWrite(os);
                    } else {
                        mAtomicFile.failWrite(os);
                    }
                }
            } catch (IOException ex) {
                Slog.w(TAG, "Failed to save input manager persistent store data.", ex);
            }
        }

        private void loadFromXml(XmlPullParser parser)
                throws IOException, XmlPullParserException {
            XmlUtils.beginDocument(parser, "input-manager-state");
            final int outerDepth = parser.getDepth();
            while (XmlUtils.nextElementWithin(parser, outerDepth)) {
                if (parser.getName().equals("input-devices")) {
                    loadInputDevicesFromXml(parser);
                }
            }
        }

        private void loadInputDevicesFromXml(XmlPullParser parser)
                throws IOException, XmlPullParserException {
            final int outerDepth = parser.getDepth();
            while (XmlUtils.nextElementWithin(parser, outerDepth)) {
                if (parser.getName().equals("input-device")) {
                    String descriptor = parser.getAttributeValue(null, "descriptor");
                    if (descriptor == null) {
                        throw new XmlPullParserException(
                                "Missing descriptor attribute on input-device");
                    }
                    InputDeviceState state = new InputDeviceState();
                    state.keyboardLayoutDescriptor =
                            parser.getAttributeValue(null, "keyboard-layout");
                    mInputDevices.put(descriptor, state);
                }
            }
        }

        private void saveToXml(XmlSerializer serializer) throws IOException {
            serializer.startDocument(null, true);
            serializer.setFeature("http://xmlpull.org/v1/doc/features.html#indent-output", true);
            serializer.startTag(null, "input-manager-state");
            serializer.startTag(null, "input-devices");
            for (Map.Entry<String, InputDeviceState> entry : mInputDevices.entrySet()) {
                final String descriptor = entry.getKey();
                final InputDeviceState state = entry.getValue();
                serializer.startTag(null, "input-device");
                serializer.attribute(null, "descriptor", descriptor);
                if (state.keyboardLayoutDescriptor != null) {
                    serializer.attribute(null, "keyboard-layout", state.keyboardLayoutDescriptor);
                }
                serializer.endTag(null, "input-device");
            }
            serializer.endTag(null, "input-devices");
            serializer.endTag(null, "input-manager-state");
            serializer.endDocument();
        }
    }

    private static final class InputDeviceState {
        public String keyboardLayoutDescriptor;
    }
}