fail to read a file with deno

[sigmaSd]

Steps to reproduce

• mkdir f; cd f
• cargo new a
• echo "hello">file
• echo 'fn main() {dbg!(std::fs::read_to_string("./file"));}'>a/src/main.rs
• cargo b --manifest-path a/Cargo.toml --target-dir target --target wasm32-wasi
• wasmer target/wasm32-wasi/debug/a.wasm --dir . # works, same for wasmtime

import { init, WASI } from "https://deno.land/x/[email protected]/wasi.ts";
await init();

const wasi = new WASI({});

const moduleBytes = await Deno.readFile(
  "./target/wasm32-wasi/debug/a.wasm",
);
const module = await WebAssembly.compile(moduleBytes);
wasi.instantiate(module, {});

const exitCode = wasi.start();
const stdout = wasi.getStdoutString();
const stderr = wasi.getStderrString();
console.log(`${stdout}${stderr}(exit code: ${exitCode})`);

fails with

[src/main.rs:1] std::fs::read_to_string("./file") = Err(
    Os {
        code: 44,
        kind: NotFound,
        message: "No such file or directory",
    },
)
(exit code: 0)

[sigmaSd]

deno wasi implementation have its own issue denoland/std#3415

[sigmaSd]

I guess I'm expecting wasi io to map to deno permissions which might not be the case, it might be that I have to pass relevant config here new WASI({})

[sigmaSd]

So thats probably it I need to use

const wasi = new WASI({ preopens: { ".": "." } });

but this fails

error: Uncaught (in promise) Error: Failed to create the WasiState: wasi filesystem creation error: `Could not get metadata for fil
e ".": fd not a directory``
        const ret = new Error(getStringFromWasm0(arg0, arg1));
                    ^
    at imports.wbg.__wbg_new_8d2af00bc1e329ee (https://deno.land/x/[email protected]/pkg/wasmer_wasi_js.js:1185:21)
    at <anonymous> (https://deno.land/x/[email protected]/pkg/wasmer_wasi_js_bg.wasm:1:19665)
    at new WASI (https://deno.land/x/[email protected]/pkg/wasmer_wasi_js.js:632:18)
    at file:///home/mrcool/dev/deno/lab/tmp/xiU/b.ts:4:14
    at eventLoopTick (ext:core/01_core.js:182:11)

using deno std implementation (https://deno.land/[email protected]/wasi/snapshot_preview1.ts) works so this maybe is a wasmerjs issue

[jeff-hykin]

Here's a temp workaround for deno:

import { WasmFs } from "@wasmer/wasmfs"
// wasmerio uses the deprecated .__proto__ = /*thing*/ to hack the prototype 
Object.defineProperty(Object.getPrototypeOf({}), "__proto__", {
    get() {
        return Object.getPrototypeOf(this)
    },
    set(value) {
        return Object.setPrototypeOf(this, value)
    }
})
const wasmFs = new WasmFs()

[sigmaSd]

@jeff-hykin you don't need that hack instead you can just use --unstable-unsafe-proto deno run --unstable-unsafe-proto a.ts

[jeff-hykin]

Cool I didnt know those existed.

That said, I'm making a library and I wouldnt want library users to need to add that flag to their runtime.

I ended up forking the dependency and getting rid of the proto usage that way. Its pretty much all from node Buffer shims.