WASI Library support in wasmer-js 1.0

[h1romas4]

Hello.

In wasmer-js 0.12.0, I was able to use the WASI module as a library (and get an export) in the following process, is there any plan to support it in the 1.0 series?

https://github.com/h1romas4/libymfm.wasm/blob/v0.9.0/examples/web/src/js/wasi_wasmer.js#L41-L73

export async function initWasi() {
    // ...snip...

    // create WASI instance
    wasi = new WASI({
        args: [""],
        env: {},
        bindings: {
            ...WASI.defaultBindings,
            fs: memFs
        }
    });
    // fetch wasm module
    const response = await fetch(new URL('../wasm/libymfm_bg.wasm', import.meta.url));
    const responseArrayBuffer = new Uint8Array(await response.arrayBuffer());
    // compile wasm
    const wasm_bytes = new Uint8Array(responseArrayBuffer).buffer;
    const lowered_wasm = await lowerI64Imports(wasm_bytes);
    let module = await WebAssembly.compile(lowered_wasm);
    // get WASI imports
    let imposts = wasi.getImports(module);
    // merge wasm imports
    //   (import "wasi_snapshot_preview1" "fd_seek" (func $__wasi_fd_seek (type $t25)))
    //   (import "./libymfm_bg.js" "__wbg_new_59cb74e423758ede"...)
    imposts['./libymfm_bg.js'] = await import('../wasm/libymfm_bg');
    const instance = await WebAssembly.instantiate(module, {
        ...imposts
    });
    // start wasi
    wasi.start(instance);
    // init wasi (Isn't this necessary?)
    instance.exports._initialize();

    // return wasm exports(for call setWasmExport())
    return instance.exports;
}

Best regards.

[syrusakbary]

Hi @h1romas4, what APIs would be useful for your use case? Just being able to access the instance and it's exports?

[h1romas4]

@syrusakbary Thank you for your responce.

Yes, I would like to have access to the instance and exports.

In my use case, main(_start) is not the only entry point, there are many export functions generated by wasm-bindgen and extern "C".

Within the exported function, there are calls to the WASI API such as println!(Rust) and fopen(C++), and I want to call these functions from JavaScript in my Web Browser.

The specific exports looks like this. (/libymfm_bg.js was generated by wasm-bindgen)

  (import "wasi_snapshot_preview1" "environ_get" (func $__imported_wasi_snapshot_preview1_environ_get (type $t8)))
  (import "wasi_snapshot_preview1" "environ_sizes_get" (func $__imported_wasi_snapshot_preview1_environ_sizes_get (type $t8)))
  (import "wasi_snapshot_preview1" "fd_close" (func $__imported_wasi_snapshot_preview1_fd_close (type $t4)))
  (import "wasi_snapshot_preview1" "fd_fdstat_get" (func $__imported_wasi_snapshot_preview1_fd_fdstat_get (type $t8)))
  (import "wasi_snapshot_preview1" "fd_fdstat_set_flags" (func $__imported_wasi_snapshot_preview1_fd_fdstat_set_flags 
  ...snip...
  (import "./libymfm_bg.js" "__wbg_new_59cb74e423758ede" (func $console_error_panic_hook::Error::new::__wbg_new_59cb74e423758ede::h5e712c4974ccece4 (type $t1)))
  (import "./libymfm_bg.js" "__wbg_stack_558ba5917b466edd" (func $console_error_panic_hook::Error::stack::__wbg_stack_558ba5917b466edd::hb1a9c3d223c10378 (type $t7)))
  (import "./libymfm_bg.js" "__wbg_error_4bb6c2a97407129a" (func $console_error_panic_hook::error::__wbg_error_4bb6c2a97407129a::h3f15166c4de92044 (type $t3)))
  (import "./libymfm_bg.js" "__wbindgen_object_drop_ref" (func $wasm_bindgen::__wbindgen_object_drop_ref::hda0f57decd45dfa0 (type $t3)))
  (import "./libymfm_bg.js" "__wbindgen_throw" (func $wasm_bindgen::__wbindgen_throw::he7308114fccb2084 (type $t7)))
  (import "wasi_snapshot_preview1" "random_get" (func $wasi::lib_generated::wasi_snapshot_preview1::random_get::he91525f4791886e0 (type $t8)))

The actual source code for wasmer-python and wasmer-js examples can be found under the examples directory in the repository below. (A synthesizer made with WebAssembly)

https://github.com/h1romas4/libymfm.wasm

Thank you!

[syrusakbary]

This issue should be now solved.
The new version v1.0.2 is now published into NPM and Deno.

[syrusakbary]

Basically, calling wasi.instantiate(...) will return the inner WebAssembly.Instance, so you can use it as needed

[h1romas4]

Thank you for your quick response!
I would like to work on migrating to 1.0.