Rust and Wasm problems when trying to access a file

[AndreaEsposit]

I have been trying to create/read/edit a file though a WebAssembly module originally written in Rust, but it is not working.

The code looks like this(src/lib.rs):

#[no_mangle]
pub fn write() -> Result<(), io::Error> {
    let mut file = File::create("./foo.txt")?;
    file.write_all(b"Hello, world!")?;
    Ok(())
}
#[no_mangle]
pub extern "C" fn hello() -> (){
    let err = write();
    match err {
        Ok(()) => print!("Managed"),
        Err(_e) => print!("Didn't manage");
    }
}

This is my cargo.toml:

[package]
name = "rust_write"
version = "0.1.0"
edition ="2018"

[lib]
crate-type = ["cdylib"]

I am using rustc 1.51.0-nightly, and I compiled the file with this command cargo build --target wasm32-wasi.
The Wa. module will not work either with wasmtime CLI ( wasmtime --dir=. --invoke hello rust_write.wasm ) or embedded, however if I remove the crate-type = ["cdylib"] from cargo.toml and write the exact same hello function as a main function in ````src/main.rs```, then it works without problems.

Could it be that the issue is that _start is not called when you directly --invoke the hello function.

Am I intended to not be able to access files if I am using a WASI library, or is it a bug?
Am I just straight up doing something wrong when I compile?

[AndreaEsposit]

Found out a way to do it here: #79997 (comment)