Function openpty 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn openpty(
    amaster: *mut c_int,
    aslave: *mut c_int,
    namep: *mut c_char,
    termp: *const termios,
    winp: *const winsize,
) -> c_int

See https://www.man7.org/linux/man-pages/man3/openpty.3.html.