Currently, I am working on a project which uses the wasmtime (a wasm runtime implemented by rust) to load and initiate some wasm modules.

And I would like a wasm module to access the global val. So I write some code:

extern "C" {
    static offset: i32;
}

#[no_mangle]
pub extern "C" fn hello() -> i32 {
    unsafe { offset }
}

And I use the command to compile it to wasm:

cargo build --target wasm32-unknown-unknown

Next, I write another rust program to load and initiate the wasm module:

use wasmtime::*;

struct MyState {
    count: i32,
}

fn main() -> Result<()> {
    let engine = Engine::default();
    let mut store = Store::new(&engine, MyState { count: 0 });

    // the path is corrected.
    let module = Module::from_file(&engine, "./src/linkerglobal.wasm")?; 
    let mut linker = Linker::new(&engine);

    // create a global value
    let ty = GlobalType::new(ValType::I32, Mutability::Var);
    let my_global = Global::new(&mut store, ty, Val::I32(0x1234))?;
    linker.define(&mut store, "host", "offset", my_global)?;


    let instance = linker.instantiate(&mut store, &module)?;


    let hello = instance.get_typed_func::<(), i32>(&mut store, "hello")?;
    let res = hello.call(&mut store, ())?;
    println!("res: {}", res); // it should be 0x1235

    Ok(())
}

I think the output should be: res: 4660, however, the output is res: 0.

Can you help me? Thanks a lot