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>

4 files changed, 19 insertions, 0 deletions

diff --git a/src/serialport/qserialport.cpp b/src/serialport/qserialport.cpp
index 1126fb9..8bf71c6 100644
--- a/src/serialport/qserialport.cpp
+++ b/src/serialport/qserialport.cpp
@@ -67,6 +67,7 @@ QSerialPortPrivate::QSerialPortPrivate()
     , handle(INVALID_HANDLE_VALUE)
     , parityErrorOccurred(false)
     , readChunkBuffer(ReadChunkSize, 0)
+    , communicationStarted(false)
     , writeStarted(false)
     , readStarted(false)
     , notifier(0)
diff --git a/src/serialport/qserialport_p.h b/src/serialport/qserialport_p.h
index 571b0de..f3b1eb8 100644
--- a/src/serialport/qserialport_p.h
+++ b/src/serialport/qserialport_p.h
@@ -236,6 +236,7 @@ public:
     HANDLE handle;
     bool parityErrorOccurred;
     QByteArray readChunkBuffer;
+    bool communicationStarted;
     bool writeStarted;
     bool readStarted;
     QWinOverlappedIoNotifier *notifier;
diff --git a/src/serialport/qserialport_win.cpp b/src/serialport/qserialport_win.cpp
index 6a1a941..0c61d36 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;
 }
 
diff --git a/tests/auto/qserialport/tst_qserialport.cpp b/tests/auto/qserialport/tst_qserialport.cpp
index c5c9113..e49b1ff 100644
--- a/tests/auto/qserialport/tst_qserialport.cpp
+++ b/tests/auto/qserialport/tst_qserialport.cpp
@@ -112,6 +112,8 @@ private slots:
 
     void controlBreak();
 
+    void clearAfterOpen();
+
 protected slots:
     void handleBytesWrittenAndExitLoopSlot(qint64 bytesWritten);
     void handleBytesWrittenAndExitLoopSlot2(qint64 bytesWritten);
@@ -910,5 +912,14 @@ void tst_QSerialPort::controlBreak()
     QCOMPARE(qvariant_cast<bool>(breakSpy.at(1).at(0)), false);
 }
 
+void tst_QSerialPort::clearAfterOpen()
+{
+    QSerialPort senderPort(m_senderPortName);
+    QVERIFY(senderPort.open(QSerialPort::ReadWrite));
+    QCOMPARE(senderPort.error(), QSerialPort::NoError);
+    QVERIFY(senderPort.clear());
+    QCOMPARE(senderPort.error(), QSerialPort::NoError);
+}
+
 QTEST_MAIN(tst_QSerialPort)
 #include "tst_qserialport.moc"