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