//! Compile arbitrary bytes from the fuzzer as if they were Wasm, checking that

//! compilation is deterministic.

//!

//! Also use `wasm-mutate` to mutate the fuzz inputs.

#![no_main]

use libfuzzer_sys::{fuzz_mutator, fuzz_target};

use wasmtime::{Config, Engine, Module, Result};

fn create_engine() -> Engine {

    let mut config = Config::default();

    // Safety: the Cranelift option `regalloc_checker` does not alter

    // the generated code at all; it only does extra checking after

    // compilation.

    unsafe {

        config.cranelift_flag_enable("regalloc_checker");

    }

    Engine::new(&config).expect("Could not construct Engine")

}

fn compile_and_serialize(engine: &Engine, wasm: &[u8]) -> Result<Vec<u8>> {

    let module = Module::new(&engine, wasm)?;

    module.serialize()

}

fuzz_target!(|data: &[u8]| {

    let engine = create_engine();

    wasmtime_fuzzing::oracles::log_wasm(data);

    if let Ok(bytes1) = compile_and_serialize(&engine, data) {

        let bytes2 = compile_and_serialize(&engine, data)

            .expect("successfully compiled once, should successfully compile again");

        // NB: Don't use `assert_eq!` here because it prints out the LHS and RHS

        // to stderr on failure, which isn't helpful here since it is just a

        // huge serialized binary.

        assert!(bytes1 == bytes2, "Wasm compilation should be deterministic");

    }

});

fuzz_mutator!(|data: &mut [u8], size: usize, max_size: usize, seed: u32| {

    // Half of the time use libfuzzer's built in mutators, and the other half of

    // the time use `wasm-mutate`.

    if seed.count_ones() % 2 == 0 {

        libfuzzer_sys::fuzzer_mutate(data, size, max_size)

    } else {

        wasmtime_fuzzing::mutators::wasm_mutate(

            data,

            size,

            max_size,

            seed,

            libfuzzer_sys::fuzzer_mutate,

        )

    }

});