2.4. cec poll()

2.4.1. Name

cec-poll - Wait for some event on a file descriptor

2.4.2. Synopsis

#include <sys/poll.h>
int poll(struct pollfd *ufds, unsigned int nfds, int timeout)

2.4.3. Arguments


List of FD events to be watched


Number of FD events at the *ufds array


Timeout to wait for events

2.4.4. Description

With the poll() function applications can wait for CEC events.

On success poll() returns the number of file descriptors that have been selected (that is, file descriptors for which the revents field of the respective struct pollfd is non-zero). CEC devices set the POLLIN and POLLRDNORM flags in the revents field if there are messages in the receive queue. If the transmit queue has room for new messages, the POLLOUT and POLLWRNORM flags are set. If there are events in the event queue, then the POLLPRI flag is set. When the function times out it returns a value of zero, on failure it returns -1 and the errno variable is set appropriately.

For more details see the poll() manual page.

2.4.5. Return Value

On success, poll() returns the number structures which have non-zero revents fields, or zero if the call timed out. On error -1 is returned, and the errno variable is set appropriately:


One or more of the ufds members specify an invalid file descriptor.


ufds references an inaccessible memory area.


The call was interrupted by a signal.


The nfds value exceeds the RLIMIT_NOFILE value. Use getrlimit() to obtain this value.