Avoid to start of communication notifier if it already is active

This happens in the QSP::clear() method, where the WaitCommEvent()
function returns with an error "The parameter is incorrect",
because it calls when the waiting already is active.

Tested with the virtual com0com and on-board serial ports.

Change-Id: I351a336f2d3c05852a654e7bccc3ff84d7aba025
Reviewed-by: Sergey Belyashov <Sergey.Belyashov@gmail.com>
Reviewed-by: Denis Shienkov <denis.shienkov@gmail.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/serialport/qserialport_win.cpp b/src/serialport/qserialport_win.cpp
index 6a1a941c..0c61d36c 100644
--- a/src/serialport/qserialport_win.cpp
+++ b/src/serialport/qserialport_win.cpp
@@ -400,6 +400,8 @@ bool QSerialPortPrivate::setDataErrorPolicy(QSerialPort::DataErrorPolicy policy)
 
 bool QSerialPortPrivate::completeAsyncCommunication(qint64 bytesTransferred)
 {
+    communicationStarted = false;
+
     if (bytesTransferred == qint64(-1))
         return false;
     if (EV_ERR & triggeredEventMask)
@@ -453,6 +455,9 @@ bool QSerialPortPrivate::completeAsyncWrite(qint64 bytesTransferred)
 
 bool QSerialPortPrivate::startAsyncCommunication()
 {
+    if (communicationStarted)
+        return true;
+
     ::ZeroMemory(&communicationOverlapped, sizeof(communicationOverlapped));
     if (!::WaitCommEvent(handle, &triggeredEventMask, &communicationOverlapped)) {
         QSerialPortErrorInfo error = getSystemError();
@@ -463,6 +468,7 @@ bool QSerialPortPrivate::startAsyncCommunication()
             return false;
         }
     }
+    communicationStarted = true;
     return true;
 }