fail to read a file with WASI

[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 Context from "https://deno.land/[email protected]/wasi/snapshot_preview1.ts";

const context = new Context({});

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

const instance = await WebAssembly.instantiate(module, {
  "wasi_snapshot_preview1": context.exports,
});

context.start(instance);

fails with

[src/main.rs:1] std::fs::read_to_string("./file") = Err(
    Custom {
        kind: Uncategorized,
        error: "failed to find a pre-opened file descriptor through which \"./file\" could be opened",
    },
)

I follow the code a bit it seems it fails here https://github.com/denoland/deno_std/blob/main/wasi/snapshot_preview1.ts#L848

it doesn't find the file fd preloaded it seems

[sigmaSd]

wasmer-js have its own issue wasmerio/wasmer-js#321

[sigmaSd]

I guess I'm expecting wasi io to map to deno permissions which might not be the case

[sigmaSd]

yes making this change makes it work

const context = new Context({ preopens: { ".": "." } });

so permissions are going to be asked on that line