[pure virtual]
Opens the device for the specified access.
Implemented in FX::QBlkSocket, FX::QBuffer, FX::QBZip2Device, FX::QChildProcess, FX::QFile, FX::QGZipDevice, FX::QIODeviceS, FX::QLocalPipe, FX::QMemMap, FX::QPipe, and FX::QSSLDevice.