Advanced UNIX Programming

I/O Polling

The function poll(2) represents another way to perform efficient I/O scheduling. It was originally developed by AT&T to be used for STREAMS file descriptors. However, poll(2) now accepts all file descriptors. The function synopsis for poll(2) is as follows:

/*
 * UnixWare 7, SGI IRIX 6.5 :
 */
#include <stropts.h>
#include <poll.h>

/*
 * HP-UX 11.x, Solaris 8 :
 */
#include <poll.h>

/*
 * IBM AIX 4.3 :
 */
#include <sys/poll.h>
#include <sys/select.h>
#include <sys/types.h>

/*
 * FreeBSD :
 */
#include <sys/types.h>
#include <poll.h>

int poll(struct pollfd *fds, unsigned int nfds, int timeout);
struct pollfd {
    int    fd;        /* file descriptor */
    short  events;    /* events to look for */
    short  revents;   /* returned events */
} ;

As you can see, the ...