Fixing a race condition in RecognitionService
Bug #3458256
If an error occurs and simultaneously user cancels the recognition, here is what happens:
1. dispatchCancel() is called since the user requested cancel. It passes the first "if" successfully.
private void dispatchCancel(IRecognitionListener listener) {
if (mCurrentCallback == null) {
if (DBG) Log.d(TAG, "cancel called with no preceding startListening - ignoring");
} else if (mCurrentCallback.mListener.asBinder() != listener.asBinder()) {
Log.w(TAG, "cancel called by client who did not call startListening - ignoring");
} else { // the correct state
RecognitionService.this.onCancel(mCurrentCallback);
mCurrentCallback = null;
if (DBG) Log.d(TAG, "canceling - setting mCurrentCallback to null");
}
}
2. Error occurs in the app, which sets the mCurrentCallback to null:
public void error(int error) throws RemoteException {
mCurrentCallback = null;
mListener.onError(error);
}
3. the second "if" is reached in dispatchCancel()
4. boom
Change-Id: I54cdcc98b495d820a2caead1709d8dee968c461e
diff --git a/core/java/android/speech/RecognitionService.java b/core/java/android/speech/RecognitionService.java
index 75a5ed5..32b2d8f 100644
--- a/core/java/android/speech/RecognitionService.java
+++ b/core/java/android/speech/RecognitionService.java
@@ -68,6 +68,8 @@
private static final int MSG_CANCEL = 3;
+ private static final int MSG_RESET = 4;
+
private final Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
@@ -81,6 +83,10 @@
break;
case MSG_CANCEL:
dispatchCancel((IRecognitionListener) msg.obj);
+ break;
+ case MSG_RESET:
+ dispatchClearCallback();
+ break;
}
}
};
@@ -128,6 +134,10 @@
}
}
+ private void dispatchClearCallback() {
+ mCurrentCallback = null;
+ }
+
private class StartListeningArgs {
public final Intent mIntent;
@@ -241,7 +251,7 @@
* @param error code is defined in {@link SpeechRecognizer}
*/
public void error(int error) throws RemoteException {
- mCurrentCallback = null;
+ Message.obtain(mHandler, MSG_RESET).sendToTarget();
mListener.onError(error);
}
@@ -278,7 +288,7 @@
* {@link SpeechRecognizer#RESULTS_RECOGNITION} as a parameter
*/
public void results(Bundle results) throws RemoteException {
- mCurrentCallback = null;
+ Message.obtain(mHandler, MSG_RESET).sendToTarget();
mListener.onResults(results);
}