use crate::fs::File; use crate::io::Read; use crate::sync::OnceLock; static SCHEME: OnceLock = OnceLock::new(); pub fn fill_bytes(bytes: &mut [u8]) { SCHEME .get_or_try_init(|| File::open("/scheme/rand")) .and_then(|mut scheme| scheme.read_exact(bytes)) .expect("failed to generate random data"); }