waffle/fuzz/fuzz_targets/differential.rs

#![no_main]
use libfuzzer_sys::fuzz_target;
use std::sync::atomic::{AtomicU64, Ordering};

use waffle::{FrontendOptions, Module};

fuzz_target!(
    |module: wasm_smith::ConfiguredModule<waffle::fuzzing::Config>| {
        let _ = env_logger::try_init();
        log::debug!("original module: {:?}", module.module);

        let orig_bytes = module.module.to_bytes();

        if waffle::fuzzing::reject(&orig_bytes[..]) {
            log::debug!("Discarding fuzz run. Body:\n{:?}", module);
            return;
        } else {
            log::info!("body: {:?}", module);
        }

        let mut config = wasmtime::Config::default();
        config.consume_fuel(true);
        let engine = wasmtime::Engine::new(&config).unwrap();
        let orig_module =
            wasmtime::Module::new(&engine, &orig_bytes[..]).expect("failed to parse original wasm");
        let mut orig_store = wasmtime::Store::new(&engine, ());
        orig_store.out_of_fuel_trap();
        orig_store.add_fuel(10000).unwrap();
        let orig_instance = wasmtime::Instance::new(&mut orig_store, &orig_module, &[]);
        let orig_instance = match orig_instance {
            Ok(orig_instance) => orig_instance,
            Err(e) => {
                log::info!("cannot run start on orig intsance ({:?}); discarding", e);
                return;
            }
        };

        let mut parsed_module =
            Module::from_wasm_bytes(&orig_bytes[..], &FrontendOptions::default()).unwrap();
        parsed_module.expand_all_funcs().unwrap();
        parsed_module.per_func_body(|body| body.optimize(&mut waffle::passes::Fuel::infinite()));
        let roundtrip_bytes = parsed_module.to_wasm_bytes().unwrap();

        if let Ok(filename) = std::env::var("FUZZ_DUMP_WASM") {
            std::fs::write(format!("{}_orig.wasm", filename), &orig_bytes[..]).unwrap();
            std::fs::write(format!("{}_roundtrip.wasm", filename), &roundtrip_bytes[..]).unwrap();
        }

        let total = TOTAL.fetch_add(1, Ordering::Relaxed);

        let roundtrip_module = wasmtime::Module::new(&engine, &roundtrip_bytes[..])
            .expect("failed to parse roundtripped wasm");
        let mut roundtrip_store = wasmtime::Store::new(&engine, ());
        roundtrip_store.out_of_fuel_trap();
        // After roundtrip, fuel consumption rate may differ. That's fine;
        // what matters is that it terminated above without a trap (hence
        // halts in a reasonable time).
        roundtrip_store.add_fuel(u64::MAX).unwrap();
        let roundtrip_instance =
            wasmtime::Instance::new(&mut roundtrip_store, &roundtrip_module, &[])
                .expect("cannot instantiate roundtripped wasm");

        // Ensure exports are equal.

        let a_globals: Vec<_> = orig_instance
            .exports(&mut orig_store)
            .filter_map(|e| e.into_global())
            .collect();
        let a_globals: Vec<wasmtime::Val> = a_globals
            .into_iter()
            .map(|g| g.get(&mut orig_store))
            .collect();
        let a_mems: Vec<wasmtime::Memory> = orig_instance
            .exports(&mut orig_store)
            .filter_map(|e| e.into_memory())
            .collect();

        let b_globals: Vec<_> = roundtrip_instance
            .exports(&mut roundtrip_store)
            .filter_map(|e| e.into_global())
            .collect();
        let b_globals: Vec<wasmtime::Val> = b_globals
            .into_iter()
            .map(|g| g.get(&mut roundtrip_store))
            .collect();
        let b_mems: Vec<wasmtime::Memory> = roundtrip_instance
            .exports(&mut roundtrip_store)
            .filter_map(|e| e.into_memory())
            .collect();

        log::info!("a_globals = {:?}", a_globals);
        log::info!("b_globals = {:?}", b_globals);

        assert_eq!(a_globals.len(), b_globals.len());
        for (a, b) in a_globals.into_iter().zip(b_globals.into_iter()) {
            match (a, b) {
                (wasmtime::Val::I32(a), wasmtime::Val::I32(b)) => assert_eq!(a, b),
                (wasmtime::Val::I64(a), wasmtime::Val::I64(b)) => assert_eq!(a, b),
                (wasmtime::Val::F32(a), wasmtime::Val::F32(b)) => assert_eq!(a, b),
                (wasmtime::Val::F64(a), wasmtime::Val::F64(b)) => assert_eq!(a, b),
                _ => panic!("mismatching types"),
            }
        }

        assert_eq!(a_mems.len(), b_mems.len());
        for (a, b) in a_mems.into_iter().zip(b_mems.into_iter()) {
            let a_data = a.data(&orig_store);
            let b_data = b.data(&roundtrip_store);
            assert_eq!(a_data, b_data);
        }

        success(total);
    }
);

static TOTAL: AtomicU64 = AtomicU64::new(0);
static SUCCESS: AtomicU64 = AtomicU64::new(0);

fn success(total: u64) {
    let value = SUCCESS.fetch_add(1, Ordering::Relaxed);
    if value % 100 == 0 {
        eprintln!("SUCCESS: {} / TOTAL: {}", value, total);
    }
}