int ioctl(int fd, int request = QPSK_GET_EVENT, struct dvb_frontend_event *ev) Arguments

int fd File descriptor returned by a previous call to open().
int request Equals FE_GET_EVENT for this command.
struct dvb_frontend_event *ev Points to the location where the event,
  if any, is to be stored. Description

This ioctl call returns a frontend event if available. If an event is not available, the behavior depends on whether the device is in blocking or non-blocking mode. In the latter case, the call fails immediately with errno set to EWOULDBLOCK. In the former case, the call blocks until an event becomes available. Return Value

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.

EWOULDBLOCK There is no event pending, and the device is in non-blocking mode.
EOVERFLOW Overflow in event queue - one or more events were lost.