Function readlinkat 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn readlinkat(
    dirfd: c_int,
    pathname: *const c_char,
    buf: *mut c_char,
    len: size_t,
) -> ssize_t

See https://pubs.opengroup.org/onlinepubs/9799919799/functions/readlinkat.html.