Wait for events on the
epoll file descriptor
epfd for a maximum time of
timeout milliseconds. The memory area pointed to by
events will contain the events that will be available for the caller.
Up to
maxevents are returned by
epoll_wait(2).
The
maxevents parameter must be greater than zero. Specifying a
timeout of -1 makes
epoll_wait(2)
wait indefinitely, while specifying a
timeout equal to zero makes
epoll_wait(2)
to return immediately even if no events are available
(return code equal to zero).
The
struct epoll_event is defined as :
typedef union epoll_data {
void *ptr;
int fd;
__uint32_t u32;
__uint64_t u64;
} epoll_data_t;
struct epoll_event {
__uint32_t events; /* Epoll events */
epoll_data_t data; /* User data variable */
};
The
data of each returned structure will contain the same data the user set with a
epoll_ctl(2)
(EPOLL_CTL_ADD,EPOLL_CTL_MOD) while the
events member will contain the returned event bit field.
When successful,
epoll_wait(2)
returns the number of file descriptors ready for the requested I/O, or zero
if no file descriptor became ready during the requested
timeout milliseconds. When an error occurs,
epoll_wait(2)
returns -1 and
errno is set appropriately.
