QAudioInput example strange behavior

[m15ch4]

Hello.

I have modified source code of QAudioInput example from QtCreator so the readMore() slot looks like:

void MainWindow::readMore()
{
    if(!m_audioInput)
        return;
    qint64 len = m_audioInput->bytesReady();
    if(len > 4096)
        len = 4096;
    qint64 l = m_input->read(m_buffer.data(), len);
    ui->plainTextEdit->appendPlainText(QString("Odczytano l = %1").arg(l));
}

void MainWindow::readMore()
{
    if(!m_audioInput)
        return;
    qint64 len = m_audioInput->bytesReady();
    if(len > 4096)
        len = 4096;
    qint64 l = m_input->read(m_buffer.data(), len);
    ui->plainTextEdit->appendPlainText(QString("Odczytano l = %1").arg(l));
}

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I thought that 'l' variable will never be greater than 4096 but it always has value of m_audioInput->bytesReady() (even if it is > 4096).

'm_input' is QIODevice and read() method shoud read at most 'len' (4096) bytes of data, so 'l' should not be greater than 4096.

If I am wrong please correct me.
Could someone explain me why is it so behaves.