SP_poll3
Checks amount of data ready to be read
Usage
#include <sp.h>
int SP_poll( mailbox mbox);
Overview
SP_poll is a way to poll a mailbox to see if any messages are available for receiving. The value returned will be < 0 if error, 0 if nothing is available, and the number of bytes waiting if something is there.
Return values
Returns 0 if nothing is available or the number of bytes available, or one of the following errors ( < 0 ):
ILLEGAL_SESSION-
The session specified by mbox is illegal. Usually because it is not active.
Releases
Unchanged in 4 releases since Debian 3.1 (Sarge).