Files
wasmtime/crates/fuzzing/src/generators.rs
Nick Fitzgerald bab59a2cd2 Fuzzing: Add test case logging and regression test template
When the test case that causes the failure can successfully be disassembled to
WAT, we get logs like this:

```
[2019-11-26T18:48:46Z INFO  wasmtime_fuzzing] Wrote WAT disassembly to: /home/fitzgen/wasmtime/crates/fuzzing/target/scratch/8437-0.wat
[2019-11-26T18:48:46Z INFO  wasmtime_fuzzing] If this fuzz test fails, copy `/home/fitzgen/wasmtime/crates/fuzzing/target/scratch/8437-0.wat` to `wasmtime/crates/fuzzing/tests/regressions/my-regression.wat` and add the following test to `wasmtime/crates/fuzzing/tests/regressions.rs`:

    ```
    #[test]
    fn my_fuzzing_regression_test() {
        let data = wat::parse_str(
            include_str!("./regressions/my-regression.wat")
        ).unwrap();
        oracles::instantiate(data, CompilationStrategy::Auto)
    }
    ```
```

If the test case cannot be disassembled to WAT, then we get logs like this:

```
[2019-11-26T18:48:46Z INFO  wasmtime_fuzzing] Wrote Wasm test case to: /home/fitzgen/wasmtime/crates/fuzzing/target/scratch/8437-0.wasm
[2019-11-26T18:48:46Z INFO  wasmtime_fuzzing] Failed to disassemble Wasm into WAT:
    Bad magic number (at offset 0)

    Stack backtrace:
        Run with RUST_LIB_BACKTRACE=1 env variable to display a backtrace

[2019-11-26T18:48:46Z INFO  wasmtime_fuzzing] If this fuzz test fails, copy `/home/fitzgen/wasmtime/crates/fuzzing/target/scratch/8437-0.wasm` to `wasmtime/crates/fuzzing/tests/regressions/my-regression.wasm` and add the following test to `wasmtime/crates/fuzzing/tests/regressions.rs`:

    ```
    #[test]
    fn my_fuzzing_regression_test() {
        let data = include_bytes!("./regressions/my-regression.wasm");
        oracles::instantiate(data, CompilationStrategy::Auto)
    }
    ```
```
2019-11-26 10:54:21 -08:00

31 lines
971 B
Rust

//! Test case generators.
//!
//! Test case generators take raw, unstructured input from a fuzzer
//! (e.g. libFuzzer) and translate that into a structured test case (e.g. a
//! valid Wasm binary).
//!
//! These are generally implementations of the `Arbitrary` trait, or some
//! wrapper over an external tool, such that the wrapper implements the
//! `Arbitrary` trait for the wrapped external tool.
use arbitrary::{Arbitrary, Unstructured};
/// A Wasm test case generator that is powered by Binaryen's `wasm-opt -ttf`.
#[derive(Debug)]
pub struct WasmOptTtf {
/// The raw, encoded Wasm bytes.
pub wasm: Vec<u8>,
}
impl Arbitrary for WasmOptTtf {
fn arbitrary<U>(input: &mut U) -> Result<Self, U::Error>
where
U: Unstructured + ?Sized,
{
let seed: Vec<u8> = Arbitrary::arbitrary(input)?;
let module = binaryen::tools::translate_to_fuzz_mvp(&seed);
let wasm = module.write();
Ok(WasmOptTtf { wasm })
}
}