#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>

#include <assert.h>
#include <err.h>
#include <unistd.h>

int
main(int argc, char **argv)
{
	struct kevent ev, out;
	int pfd[2], kq;
	char ch;

	if (pipe(pfd) != 0)
		err(1, "pipe");

	kq = kqueue();
	if (kq < 0)
		err(1, "kqueue");

	if (write(pfd[1], "a", 1) != 1)
		err(1, "write");

	EV_SET(&ev, pfd[0], EVFILT_READ, EV_ADD | EV_DISABLE, 0, 0, NULL);

	if (kevent(kq, &ev, 1, NULL, 0, NULL) != 0)
		err(1, "kevent1");

	EV_SET(&ev, pfd[0], EVFILT_READ, EV_ENABLE, 0, 0, NULL);

	if (kevent(kq, &ev, 1, &out, 1, NULL) != 1)
		err(1, "kevent2");

	assert(out.ident == pfd[0]);
	assert(out.filter == EVFILT_READ);

	return (0);
}