O_ASYNC
ATF_REQUIRE_ERRNO(EINVAL, pipe2(fd, O_ASYNC) == -1);
assert(fcntl(fds[0], F_SETFL, flags | O_ASYNC) == 0);
assert(fcntl(fds[0], F_SETFL, flags | O_ASYNC) == 0);
assert(fcntl(fds[0], F_SETFL, flags | O_ASYNC | O_NONBLOCK) == 0);
assert(fcntl(sock, F_SETFL, flags | O_ASYNC) == 0);
if (fcntl(0, F_SETFL, O_ASYNC) == -1)
#define FASYNC O_ASYNC /* kernel/compat */