[ruby-head-wasm-wasi] Is there any way to disable `js` module?

[riywo]

I'd like to use ruby.wasm as a sandboxed interpreter in browser i.e. just for pure computation with restricted DOM access because it executes untrusted code.

It looks like js module is available by default in ruby-head-wasm-wasi's DefaultRubyVM, but is there any way to disable it?
https://github.com/ruby/ruby.wasm/tree/main/packages/npm-packages/ruby-head-wasm-wasi#quick-start-for-browser

I'm a novice in the WebAssembly world, so it'll take time to read the whole code base of ruby.wasm for me. Therefore, I'm asking such a question beforehand in case someone already knows the answer...

Sorry for bothering you guys.

[kateinoigakukun]

Thank you for opening an interesting topic!
If you need only need Ruby interpreter, you don't need ruby-head-wasm-wasi package at all. You can use non -js suffixed artifacts like below:

1. Install browser compatible WASI implementation:

$ npm install uwasi

2. Download ruby.wasm binary that does not link js extension

$ curl -L curl -L https://github.com/ruby/ruby.wasm/releases/download/2022-12-02-a/ruby-head-wasm32-unknown-wasi-minimal.tar.gz | tar xz --strip-components=1

3. Setup JS code to launch WASI app

import { WASI, useAll } from "uwasi";

async function main() {
    const wasi = new WASI({
        args: ["ruby.wasm", "-e", "puts :Hello"],
        features: [useAll()],
    });
    const response = await fetch("./usr/local/bin/ruby.wasm");
    const buffer = await response.arrayBuffer();
    const { instance } = await WebAssembly.instantiate(buffer, {
        wasi_snapshot_preview1: wasi.wasiImport,
    });
    const exitCode = wasi.start(instance);
    console.log("exit code:", exitCode);
}

main()

[riywo]

Amazing! That's a nice idea.

Just curious: Where is this js module implemented? I might need a custom module to import some JS functionality to the ruby world, so I wonder where I can refer the js module.

[kateinoigakukun]

The js extension is implemented here: https://github.com/ruby/ruby.wasm/tree/main/ext/js
If you want to import some of functionalities from outside of the Wasm program (it means importing from JS on browser), you can add import entries like:

ruby.wasm/ext/js/bindgen/rb-js-abi-host.c

Lines 78 to 79 in 802ecc5

	__attribute__((import_module("rb-js-abi-host"), import_name("eval-js: func(code: string) -> variant { success(handle<js-abi-value>), failure(handle<js-abi-value>) }")))
	void __wasm_import_rb_js_abi_host_eval_js(int32_t, int32_t, int32_t);

You need to write your own C extension to import them, and you need to change Rakefile to build and link it into ruby.wasm

[riywo]

I really appreciate your kind responses. I'll try to integrate ruby.wasm with my project!