Fix thread affinity of FingerprintManager.

FingerprintManager internally creates a Handler which needs to be
bound to a Looper thread. Prior to this CL the Handler was bound to
the Looper of the current thread. This caused issues:
* Different instances of FingerprintManager could be bound to
  different Looper threads.
* Callbacks from FingerprintManager were invoked on arbitrary
  threads (or not at all if the Looper was there but wasn't running).
* FingerprintManager couldn't be obtained by apps on most non-main
  threads leading to java.lang.RuntimeException: Can't create handler
  inside thread that has not called Looper.prepare().

This CL fixes the issue by binding the FingerprintManager's Handler to
the Looper running on the main thread.

Bug: 20725228
Change-Id: I4a0382d6e11df9f23b8db9f0deec77369af31b5e

1 files changed, 8 insertions, 1 deletions

diff --git a/core/java/android/hardware/fingerprint/FingerprintManager.java b/core/java/android/hardware/fingerprint/FingerprintManager.java
index 779448b..cf96145 100644
--- a/core/java/android/hardware/fingerprint/FingerprintManager.java
+++ b/core/java/android/hardware/fingerprint/FingerprintManager.java
@@ -626,7 +626,13 @@ public class FingerprintManager {
         return 0;
     }
 
-    private Handler mHandler = new Handler() {
+    private Handler mHandler;
+
+    private class MyHandler extends Handler {
+        private MyHandler(Context context) {
+            super(context.getMainLooper());
+        }
+
         public void handleMessage(android.os.Message msg) {
             switch(msg.what) {
                 case MSG_ENROLL_RESULT:
@@ -711,6 +717,7 @@ public class FingerprintManager {
         if (mService == null) {
             Slog.v(TAG, "FingerprintManagerService was null");
         }
+        mHandler = new MyHandler(context);
     }
 
     private int getCurrentUserId() {