Compile Wasabi to WebAssembly itself, do instrumentation "just before instantiation" #13
Comments
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Hi Daniel, Thank you for your work on Wasabi! I took a stab at compiling Wasabi to WebAssembly and this is what I have: // lib.rs
#[derive(Serialize)]
pub struct Instrument {
pub output: Vec<u8>,
pub js: String
}
#[wasm_bindgen]
pub fn instrument(bytes: &[u8]) -> JsValue {
console_error_panic_hook::set_once();
let mut module: Module = LLModule::decode(&mut BufReader::new(bytes)).unwrap().into();
let enabled_hooks = EnabledHooks::all();
let js = add_hooks(&mut module, &enabled_hooks).unwrap();
let mut wasm: Vec<u8> = Vec::new();
{
let mut writer = BufWriter::new(&mut wasm);
let llmodule: LLModule = module.into();
llmodule.encode(&mut writer);
}
let ret = Instrument {
output: wasm,
js: js
};
return JsValue::from_serde(&ret).unwrap();
}Full diff available here: https://gist.github.com/rxEckT/1b37a10197751b10110ca536aded811d You should be able to use this html as a harness after building <!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<body>
<form>
<input id="uploadWasm" type="file" name="Upload...">
</form>
<script type="module">
import init, { instrument } from "./wasabi.js";
function instrument() {
const file = this.files[0];
const reader = new FileReader();
reader.onload = function(e) {
const bytes = new Uint8Array(e.target.result);
const result = instrument(bytes);
window.result = result;
// open console and play with window.result
// (new Function(result.js))();
// WebAssembly.instantiate(Uint8Array.from(result.output))...
}
reader.readAsArrayBuffer(file);
}
document.getElementById("uploadWasm").addEventListener("change", instrument, false);
</script>
</body>
</html> |
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Hi rxEckT, Ah nice, that looks very good indeed :-) If you are fine with the MIT license of the project, I will use this as a basis for implementing it with a bit more automation (e.g., patching WebAssembly.instantiate to instrument all wasm files). Since I am travelling right now, I will have to take a look at it later. But thanks for taking it already this far! Out of curiosity: are you using that code yourself? And more general: Are you doing research with Wasabi? |
No problem, go ahead :)
It's actually something I barely scrapped together without knowing Rust (it was hard work!)
Unfortunately no, but I do think Wasabi opens up a lot of possibilities for research, as noted in your paper :D |
Motivation: no "offline" instrumentation step necessary any longer, could (in principle) just add one
wasabi.jsfile (with wasm inline) that does all the instrumentation + JS codegenPotential steps:
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