How to export Substrate native interface to runtime? - substrate

Question

I'm trying link the substrate tutorial (https://github.com/substrate-developer-hub/substrate-node-template) to some C library. I wrapped the C library to a crate called cfun, which can called by the node layer.
I figured out I can use the marco runtime_interface to export the native interface for my pallets to call. However, although I can compile successfully, the wasm runtime cannot instantiate.
Any idea what is happening?
// node/cfun/src/lib.rs
#![cfg_attr(not(feature = "std"), no_std)]
#[link(name = "test", kind = "static")]
extern "C" {
pub fn double_int(input: i32) -> i32;
pub fn double_uint(input: u32) -> u32;
}
# node/cint/Cargo.toml
[package]
edition = '2018'
name = 'cint'
version = '2.0.1'
[dependencies]
# local dependencies
sp-runtime-interface = { version = "2.0.1", default-features = false}
cfun = { path = '../cfun', default-features = false, version = '2.0.1', optional = true }
[features]
default = ['std']
std = [
'sp-runtime-interface/std',
'cfun',
]
// node/cint/src/lib.rs
#![cfg_attr(not(feature = "std"), no_std)]
#[cfg(feature = "std")]
extern crate cfun;
use sp_runtime_interface::runtime_interface;
#[runtime_interface]
pub trait CFunctions {
fn c_double_uint(input: u32) -> u32 {
unsafe {
cfun::double_uint(input)
}
}
}
// pallets/template/src/lib.rs
// import module at the beginning
extern crate cint;
// ...
// modify the original `do_something` function
// from:
// Something::put(something);
// to:
let smt = cint::c_functions::c_double_uint(something);
Something::put(smt);
Edited 1
# pallets/template.Cargo.toml and runtime/Cargo.toml
# path is a bit different, but both included all interfaces
[dependencies]
# ...
sp-runtime-interface = { version = "2.0.1", default-features = false}
cfun = { path = '../../node/cfun', default-features = false, version = '2.0.1', optional = true }
cint = { path = '../../node/cint', default-features = false, version = '2.0.1'}
[features]
default = ['std']
std = [
# ...
'sp-runtime/std',
'cfun',
'cint/std',
]
Repo:
https://github.com/killalau/substrate-node-template/tree/franky