User`s guide

KwikNet TCP/IP Sockets

DAK

213

Returns If successful, this procedure returns the total number of ready sockets

identified in the descriptor sets. The variables

*readfds, *writefds and

*exceptfds are updated to identify the subset of the sockets specified by

the caller which match their respective criteria.

This procedure returns 0 if the specified timeout interval elapses before

any sockets are ready.

On failure, the error status -1 is returned. Unfortunately, the error

indicator defining the reason for failure cannot be recorded. You cannot

use

kn_errno() to retrieve the error code since you do not have a unique

socket descriptor to interrogate. The following error codes, although not

available for testing, still define the possible reasons for failure.

EBADF A socket descriptor in one of the sets is invalid.

ENOBUFS Memory needed to service the request is unavailable.