//! SHA-1, from C.
//!
//! Provided because the WebSocket handshake needs it, as
//! [`crate::helpers::sha1`] notes; it is not a general-purpose hash to build
//! anything new on.
use crate;
/// The SHA-1 digest of `data`, owned by the caller. Always 20 octets.
///
/// A null `data` hashes the empty input.
///
/// # Safety
///
/// `data` must either be null or point to `data_len` readable octets.
pub unsafe extern "C"