pub fn ioctl_fioclex<Fd: AsFd>(fd: &Fd) -> Result<()>
ioctl(fd, FIOCLEX)—Set the close-on-exec flag.
ioctl(fd, FIOCLEX)
Also known as fcntl(fd, F_SETFD, FD_CLOEXEC).
fcntl(fd, F_SETFD, FD_CLOEXEC)