NET_GET_IF - Read the configuration data of an interface created via - NET_ADD_IF.
The NET_GET_IF ioctl uses the interface number given by the struct dvb_net_if::ifnum field and fills the content of struct dvb_net_if with the packet ID and encapsulation type used on such interface. If the interface was not created yet with NET_ADD_IF, it will return -1 and fill the errno with EINVAL error code.
On success 0 is returned, on error -1 and the errno variable is set appropriately. The generic error codes are described at the Generic Error Codes chapter.