Added and exception in the read_frame function to notify that no data is available.

src/can/can.cpp

@@ -304,13 +304,15 @@ void CCAN::read_frame(unsigned int *can_id, unsigned char *data, int *len)
     frame=this->rx_frames.front();
     this->rx_frames.pop();
     *can_id=frame.can_id;
-    *len=frame.can_dlc;
+    *len=frame.can_dlc; //COMMENT: Do we need a cast ? frame.can_dlc is __u8 type variable (see /usr/include/linux/can.h) 
     for(i=0;i<frame.can_dlc;i++)
       data[i]=frame.data[i];
   }
   else
   {
     /* handle exceptions */
+    this->can_access.exit();    
+    throw CCommException(_HERE_,"No data available",this->comm_id);
   }
   this->can_access.exit();
 }