VND_POLLFD(3VND)VND_POLLFD(3VND)NAME
vnd_pollfd - get file descriptor for polling
SYNOPSIS
cc [ flag... ] file... -lvnd [ library... ]
#include <libvnd.h>
int vnd_pollfd(vnd_handle_t *vhp);
DESCRIPTION
The vnd_pollfd() function returns an integer id which corresponds to
the file descriptor that represents the underlying device that is asso‐
ciated with the vnd handle vhp. This file descriptor is suitable for
use with port_associate(3C) and similar polling techniques such as
poll(2). Use of the file descriptor outside of these uses may cause
undocumented behavior from the rest of the library.
The file descriptor in question is still managed by libvnd. The caller
must not call close(2) on it. Once vnd_close(3VND) has been called, any
further use of the file descriptor is undefined behavior.
RETURN VALUES
The function returns the integer id of the file descriptor that corre‐
sponds to the underlying vnd device.
EXAMPLES
Example 1 Use event ports for vnd notifications
The following sample C program shows how to use the vnd_pollfd function
with event ports to be notified whenever there is data available to be
read. This program assumes that a vnd device named "vnd0" exists in the
current zone. For an example of creating the device, see Example 1 in
vnd_create(3VND).
#include <libvnd.h>
#include <port.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
int
main(void)
{
vnd_handle_t *vhp;
vnd_errno_t vnderr;
int port, syserr, vfd, ret;
port = port_create();
if (port < 0) {
perror("port_create");
return (1);
}
vhp = vnd_open(NULL, "vnd0", &vnderr, &syserr);
if (vhp == NULL) {
if (vnderr == VND_E_SYS)
(void) fprintf(stderr, "failed to open device: %s",
vnd_strsyserror(syserr));
else
(void) fprintf(stderr, "failed to open device: %s",
vnd_strerror(vnderr));
(void) close(port);
return (1);
}
vfd = vnd_pollfd(vhp);
if (fcntl(vfd, F_SETFL, O_NONBLOCK) != 0) {
perror("fcntl");
vnd_close(vhp);
(void) close(port);
return (1);
}
if (port_associate(port, PORT_SOURCE_FD, vfd, POLLIN, NULL) != 0) {
perror("port_associate");
vnd_close(vhp);
(void) close(port);
return (1);
}
for (;;) {
port_event_t pe;
if (port_get(port, &pe, NULL) != 0) {
if (errno == EINTR)
continue;
perror("port_get");
vnd_close(vhp);
(void) close(port);
return (1);
}
/*
* Read the data with vnd_frameio_read(3VND) and
* optionally break out of the loop or continue to the
* next iteration and reassociate vfd with the event
* port.
*/
}
}
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌───────────────┬─────────────────────────────────┐
│ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├───────────────┼─────────────────────────────────┤
│Stability │ Committed │
├───────────────┼─────────────────────────────────┤
│MT-Level │ See "THREADING" in libvnd(3LIB) │
└───────────────┴─────────────────────────────────┘
SEE ALSOclose(2), poll(2), port_create(3C), libvnd(3LIB), vnd_close(3VND)
Feb 21, 2014 VND_POLLFD(3VND)
