Protect notification callback parameters with a mutex.

This avoids the race condition where notifications are dispatched to a NULL receiver
after notifications have been disabled.

Change-Id: I6d351ffbee97616e2c35559c132a6c5e6a66948a
related-to-bug: 3394139

1 files changed, 14 insertions, 4 deletions

diff --git a/include/media/MediaPlayerInterface.h b/include/media/MediaPlayerInterface.h
index c0963a6..048f041 100644
--- a/include/media/MediaPlayerInterface.h
+++ b/include/media/MediaPlayerInterface.h
@@ -126,8 +126,6 @@ public:
     virtual status_t    setLooping(int loop) = 0;
     virtual player_type playerType() = 0;
 
-    virtual void        setNotifyCallback(void* cookie, notify_callback_f notifyFunc) {
-                            mCookie = cookie; mNotify = notifyFunc; }
     // Invoke a generic method on the player by using opaque parcels
     // for the request and reply.
     //
@@ -149,9 +147,21 @@ public:
         return INVALID_OPERATION;
     };
 
-    virtual void        sendEvent(int msg, int ext1=0, int ext2=0) { if (mNotify) mNotify(mCookie, msg, ext1, ext2); }
+    void        setNotifyCallback(
+            void* cookie, notify_callback_f notifyFunc) {
+        Mutex::Autolock autoLock(mNotifyLock);
+        mCookie = cookie; mNotify = notifyFunc;
+    }
 
-protected:
+    void        sendEvent(int msg, int ext1=0, int ext2=0) {
+        Mutex::Autolock autoLock(mNotifyLock);
+        if (mNotify) mNotify(mCookie, msg, ext1, ext2);
+    }
+
+private:
+    friend class MediaPlayerService;
+
+    Mutex               mNotifyLock;
     void*               mCookie;
     notify_callback_f   mNotify;
 };