Function erlang_nif_sys::erlang_nif_sys_api::enif_make_string_len

pub unsafe extern "C" fn enif_make_string_len(
    env: *mut ErlNifEnv, 
    string: *const c_uchar, 
    len: size_t, 
    arg1: ErlNifCharEncoding
) -> ERL_NIF_TERM

See enif_make_string_len in the Erlang docs.