QAbstractSocket: do not fail writing on read buffer overflow

canReadNotification() could return 'false' if either the socket has
been closed, or the read buffer has reached the maximum size. Because of
this duality, waitForBytesWritten() should not fail as a result of a
canReadNotification() call.

Change-Id: I9a15fa174a3b982a7ce404913caa38fc19f64622
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Markus Goetz (Woboq GmbH) <markus@woboq.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/tests/auto/network/socket/qtcpsocket/tst_qtcpsocket.cpp b/tests/auto/network/socket/qtcpsocket/tst_qtcpsocket.cpp
index c9561fc110..7565097942 100644
--- a/tests/auto/network/socket/qtcpsocket/tst_qtcpsocket.cpp
+++ b/tests/auto/network/socket/qtcpsocket/tst_qtcpsocket.cpp
@@ -197,6 +197,7 @@ private slots:
     void clientSendDataOnDelayedDisconnect();
     void serverDisconnectWithBuffered();
     void socketDiscardDataInWriteMode();
+    void writeOnReadBufferOverflow();
     void readNotificationsAfterBind();
 
 protected slots:
@@ -3067,6 +3068,40 @@ void tst_QTcpSocket::socketDiscardDataInWriteMode()
     delete socket;
 }
 
+// Test waitForBytesWritten() does not fail on read buffer overflow
+void tst_QTcpSocket::writeOnReadBufferOverflow()
+{
+    QFETCH_GLOBAL(bool, setProxy);
+    if (setProxy)
+        return;
+
+    QTcpServer tcpServer;
+    QTcpSocket *socket = newSocket();
+
+    QVERIFY(tcpServer.listen(QHostAddress::LocalHost));
+    socket->setReadBufferSize(1);
+    socket->connectToHost(tcpServer.serverAddress(), tcpServer.serverPort());
+    QVERIFY(socket->waitForConnected(5000));
+    QCOMPARE(socket->state(), QAbstractSocket::ConnectedState);
+
+    // Accept connection on server side
+    QVERIFY2(tcpServer.waitForNewConnection(5000), "Network timeout");
+    QTcpSocket *newConnection = tcpServer.nextPendingConnection();
+    QVERIFY(newConnection != nullptr);
+    QCOMPARE(newConnection->write("1", 2), Q_INT64_C(2));
+    QVERIFY(newConnection->flush());
+
+    // Wait for buffer overflow
+    QVERIFY(socket->waitForReadyRead(5000));
+    QCOMPARE(socket->bytesAvailable(), Q_INT64_C(1));
+    // Write data and wait for successful send
+    QVERIFY(socket->putChar(0));
+    QVERIFY(socket->waitForBytesWritten(5000));
+
+    delete newConnection;
+    delete socket;
+}
+
 // Test that the socket does not enable the read notifications in bind()
 void tst_QTcpSocket::readNotificationsAfterBind()
 {