EFD_CLOEXEC
nflags |= EFD_CLOEXEC;
if (flags & ~(EFD_CLOEXEC | EFD_NONBLOCK | EFD_SEMAPHORE)) {
fd_set_exclose(l, fd, !!(flags & EFD_CLOEXEC));
eventfd(0, ~(EFD_SEMAPHORE | EFD_CLOEXEC | EFD_NONBLOCK)) == -1);
ATF_REQUIRE((efd = eventfd(1, EFD_NONBLOCK | EFD_CLOEXEC)) >= 0);