Xselect.c File Reference

Xselect(), Xpoll() - synchronous I/O multiplexing. More...

#include "Xsocket.h"

Functions
int	Xpoll (struct pollfd *ufds, unsigned nfds, int timeout)
	waits for one of a set of Xsockets or file descriptors to become ready to perform I/O. More...
int	Xselect (int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds, struct timeval *timeout)
	waits for one of a set of Xsockets to become ready to perform I/O. More...

Function Documentation

int Xpoll	(	struct pollfd *	ufds,
		unsigned	nfds,
		int	timeout
	)

Xsocket specific version of poll. See the poll man page for more detailed information. This function is compatible with Xsockets as well as regular sockets and fds. Xsockets are polled via click, and regular sockets and fds are handled through the normal poll API.

Parameters

ufds	array of pollfds indicating sockets and states to check for
nfds	number of entries in ufds socket ids specified as 0 or negative will be ignored valid flags for events are POLLIN | POLLOUT | POLLERR revents contains the returned flags and can be POLLIN | POLLOUT | POLLERR | POLLINVAL | POLLHUP
timeout	number of milliseconds to wait for an event to happen

Returns

0 if timeout occured

a positive integer indicating the number of sockets with return events

-1 with errno set if an error occured

int Xselect	(	int	nfds,
		fd_set *	readfds,
		fd_set *	writefds,
		fd_set *	errorfds,
		struct timeval *	timeout
	)

Xsocket specific version of select. See the select man page for more detailed information. This function is compatible with Xsockets as well as regular sockets and fds. Xsockets are handled with the Xpoll APIs via click, and regular sockets and fds are handled through the normal select API.

Parameters

nfds	The highest socket number contained in the fd_sets plus 1
readfds	fd_set containing sockets to check for readability
writefds	fd_set containing sockets to check for writability
errorfds	fd_set containing sockets to check for errors
timeout	amount of time to wait for a socket to change state

Returns

greater than 0, number of sockets ready

0 if the timeout expired

less than 0 if an error occurs

Warning

this function is only valid for stream and datagram sockets.