pub unsafe extern "C" fn crypt_keyslot_add_by_keyfile_device_offset(
    cd: *mut crypt_device,
    keyslot: c_int,
    keyfile: *const c_char,
    keyfile_size: usize,
    keyfile_offset: u64,
    new_keyfile: *const c_char,
    new_keyfile_size: usize,
    new_keyfile_offset: u64
) -> c_int