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¶
- ufds
- List of FD events to be watched 
- nfds
- Number of FD events at the *ufds array 
- timeout
- 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:
- EBADF
- One or more of the - ufdsmembers specify an invalid file descriptor.
- EFAULT
- ufdsreferences an inaccessible memory area.
- EINTR
- The call was interrupted by a signal. 
- EINVAL
- The - nfdsvalue exceeds the- RLIMIT_NOFILEvalue. Use- getrlimit()to obtain this value.