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Commit d535ead2 authored by Zhentao Sun's avatar Zhentao Sun
Browse files

Fixed b/10512887. 

This is an issue caused by multi-threading. If geofence provider service
is connected and disconnected immediately, the ServiceWatcher can return a
null service handle to the private thread used by GeofenceProxy, and
this can cause NPE and system crash.
This CL also fixed a hidden race conditions bug where mGeofenceHardware
is not synchronized between two threads.

Change-Id: I824642cd638fbb1e6799a5a1220b047ebc2556a1
parent 7be3a138

services/java/com/android/server/location/GeofenceProxy.java

+45 −30
Original line number Diff line number Diff line
@@ -41,11 +41,15 @@ public final class GeofenceProxy { 
    private static final String TAG = "GeofenceProxy";

    private static final String SERVICE_ACTION =

            "com.android.location.service.GeofenceProvider";

    private ServiceWatcher mServiceWatcher;

    private Context mContext;

    private final ServiceWatcher mServiceWatcher;

    private final Context mContext;

    private final IGpsGeofenceHardware mGpsGeofenceHardware;

    private final IFusedGeofenceHardware mFusedGeofenceHardware;



    private final Object mLock = new Object();



    // Access to mGeofenceHardware needs to be synchronized by mLock.

    private IGeofenceHardware mGeofenceHardware;

    private IGpsGeofenceHardware mGpsGeofenceHardware;

    private IFusedGeofenceHardware mFusedGeofenceHardware;



    private static final int GEOFENCE_PROVIDER_CONNECTED = 1;

    private static final int GEOFENCE_HARDWARE_CONNECTED = 2;
@@ -90,10 +94,6 @@ public final class GeofenceProxy { 
        return mServiceWatcher.start();

    }



    private IGeofenceProvider getGeofenceProviderService() {

        return IGeofenceProvider.Stub.asInterface(mServiceWatcher.getBinder());

    }



    private void bindHardwareGeofence() {

        mContext.bindServiceAsUser(new Intent(mContext, GeofenceHardwareService.class),

                mServiceConnection, Context.BIND_AUTO_CREATE, UserHandle.OWNER);
@@ -102,26 +102,34 @@ public final class GeofenceProxy { 
    private ServiceConnection mServiceConnection = new ServiceConnection() {

        @Override

        public void onServiceConnected(ComponentName name, IBinder service) {

            synchronized (mLock) {

                mGeofenceHardware = IGeofenceHardware.Stub.asInterface(service);

                mHandler.sendEmptyMessage(GEOFENCE_HARDWARE_CONNECTED);

            }

        }



        @Override

        public void onServiceDisconnected(ComponentName name) {

            synchronized (mLock) {

                mGeofenceHardware = null;

                mHandler.sendEmptyMessage(GEOFENCE_HARDWARE_DISCONNECTED);

            }

        }

    };



    private void setGeofenceHardwareInProvider() {

    private void setGeofenceHardwareInProviderLocked() {

        try {

            getGeofenceProviderService().setGeofenceHardware(mGeofenceHardware);

            IGeofenceProvider provider = IGeofenceProvider.Stub.asInterface(

                      mServiceWatcher.getBinder());

            if (provider != null) {

                provider.setGeofenceHardware(mGeofenceHardware);

            }

        } catch (RemoteException e) {

            Log.e(TAG, "Remote Exception: setGeofenceHardwareInProvider: " + e);

            Log.e(TAG, "Remote Exception: setGeofenceHardwareInProviderLocked: " + e);

        }

    }



    private void setGpsGeofence() {

    private void setGpsGeofenceLocked() {

        try {

            mGeofenceHardware.setGpsGeofenceHardware(mGpsGeofenceHardware);

        } catch (RemoteException e) {
@@ -129,7 +137,7 @@ public final class GeofenceProxy { 
        }

    }



    private void setFusedGeofence() {

    private void setFusedGeofenceLocked() {

        try {

            mGeofenceHardware.setFusedGeofenceHardware(mFusedGeofenceHardware);

        } catch(RemoteException e) {
@@ -140,30 +148,37 @@ public final class GeofenceProxy { 
    // This needs to be reworked, when more services get added,

    // Might need a state machine or add a framework utility class,

    private Handler mHandler = new Handler() {

        private boolean mGeofenceHardwareConnected = false;

        private boolean mGeofenceProviderConnected = false;





        @Override

        public void handleMessage(Message msg) {

            switch (msg.what) {

                case GEOFENCE_PROVIDER_CONNECTED:

                    mGeofenceProviderConnected = true;

                    if (mGeofenceHardwareConnected) {

                        setGeofenceHardwareInProvider();

                    synchronized (mLock) {

                        if (mGeofenceHardware != null) {

                            setGeofenceHardwareInProviderLocked();

                        }

                        // else: the geofence provider will be notified when the connection to

                        // GeofenceHardwareService is established.

                    }

                    break;

                case GEOFENCE_HARDWARE_CONNECTED:

                    setGpsGeofence();

                    setFusedGeofence();

                    mGeofenceHardwareConnected = true;

                    if (mGeofenceProviderConnected) {

                        setGeofenceHardwareInProvider();

                    synchronized (mLock) {

                        // Theoretically this won't happen because once the GeofenceHardwareService

                        // is connected to, we won't lose connection to it because it's a system

                        // service. But this check does make the code more robust.

                        if (mGeofenceHardware != null) {

                            setGpsGeofenceLocked();

                            setFusedGeofenceLocked();

                            setGeofenceHardwareInProviderLocked();

                        }

                    }

                    break;

                case GEOFENCE_HARDWARE_DISCONNECTED:

                    mGeofenceHardwareConnected = false;

                    setGeofenceHardwareInProvider();

                    synchronized (mLock) {

                        if (mGeofenceHardware == null) {

                            setGeofenceHardwareInProviderLocked();

                        }

                    }

                    break;

            }

        }