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