Fix stalling of reading with the limited buffer size on *nix

When the read buffer with a limited size is used, the read notifier
becomes disabled when the buffer completely is filled. The notifier
should be enabled again when several bytes were read from the read
buffer.

Change-Id: I723253fb153a1144009579141fa0ce1aca93b648
Reviewed-by: Sergey Belyashov <Sergey.Belyashov@gmail.com>
Reviewed-by: Denis Shienkov <denis.shienkov@gmail.com>

1 files changed, 45 insertions, 0 deletions

diff --git a/tests/auto/qserialport/tst_qserialport.cpp b/tests/auto/qserialport/tst_qserialport.cpp
index d50afe9..3a62bfa 100644
--- a/tests/auto/qserialport/tst_qserialport.cpp
+++ b/tests/auto/qserialport/tst_qserialport.cpp
@@ -120,6 +120,8 @@ private slots:
     void asynchronousWriteByTimer_data();
     void asynchronousWriteByTimer();
 
+    void asyncReadWithLimitedReadBufferSize();
+
     void readBufferOverflow();
     void readAfterInputClear();
     void synchronousReadWriteAfterAsynchronousReadWrite();
@@ -808,6 +810,49 @@ void tst_QSerialPort::asynchronousWriteByTimer()
     QCOMPARE(receiverPort.readAll(), alphabetArray);
 }
 
+class AsyncReader2 : public QObject
+{
+    Q_OBJECT
+public:
+    explicit AsyncReader2(QSerialPort &port, const QByteArray &expectedData)
+        : serialPort(port), expectedData(expectedData)
+    {
+        connect(&serialPort, &QSerialPort::readyRead, this, &AsyncReader2::receive);
+    }
+
+private slots:
+    void receive()
+    {
+        receivedData.append(serialPort.readAll());
+        if (receivedData == expectedData)
+            tst_QSerialPort::exitLoop();
+    }
+
+private:
+    QSerialPort &serialPort;
+    const QByteArray expectedData;
+    QByteArray receivedData;
+};
+
+void tst_QSerialPort::asyncReadWithLimitedReadBufferSize()
+{
+    QSerialPort senderPort(m_senderPortName);
+    QVERIFY(senderPort.open(QSerialPort::WriteOnly));
+
+    QSerialPort receiverPort(m_receiverPortName);
+    QVERIFY(receiverPort.open(QSerialPort::ReadOnly));
+
+    receiverPort.setReadBufferSize(1);
+    QCOMPARE(receiverPort.readBufferSize(), qint64(1));
+
+    AsyncReader2 reader(receiverPort, alphabetArray);
+
+    QCOMPARE(senderPort.write(alphabetArray), qint64(alphabetArray.size()));
+
+    enterLoop(1);
+    QVERIFY2(!timeout(), "Timed out when waiting for the read or write.");
+}
+
 void tst_QSerialPort::readBufferOverflow()
 {
     QSerialPort senderPort(m_senderPortName);