nordisk/heimdall

crates/heimdall-wasm/tests/rust-guest/src/lib.rs

// SPDX-License-Identifier: AGPL-3.0-only
//! A Rust guest for heimdall-wasm's tests (Heimdall is a defensive sandbox):
//! 'T…' input is refused, 'M…' panics (a trap), 'L…' loops forever, anything
//! else is emitted as `echo.bin` plus a `params.txt`, and accepted.

wit_bindgen::generate!({ path: "../../wit/heimdall.wit", world: "job" });

struct G;

impl Guest for G {
    fn run(input: Vec<u8>, params: Vec<Param>) -> Result<Output, Refusal> {
        match input.first() {
            Some(b'T') => {
                return Err(Refusal {
                    reason: "tampered input".to_string(),
                })
            }
            Some(b'M') => panic!("malformed input"),
            Some(b'L') => {
                let mut x: u64 = 0;
                loop {
                    x = std::hint::black_box(x.wrapping_add(1));
                }
            }
            _ => {}
        }
        emit_file("echo.bin", &input);
        let listed: Vec<String> = params
            .iter()
            .map(|p| format!("{}={}", p.key, p.value))
            .collect();
        emit_file("params.txt", listed.join("\n").as_bytes());
        Ok(Output {
            note: format!("accepted {} bytes", input.len()),
        })
    }
}

export!(G);