add decoder fuzzer

fuzz/Cargo.toml

@@ -0,0 +1,25 @@
+
+[package]
+name = "parity-wasm-fuzz"
+version = "0.0.1"
+authors = ["Automatically generated"]
+publish = false
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies.parity-wasm]
+path = ".."
+[dependencies.libfuzzer-sys]
+git = "https://github.com/rust-fuzz/libfuzzer-sys.git"
+
+[dependencies.mktemp]
+version = "0.3.1"
+
+# Prevent this from interfering with workspaces
+[workspace]
+members = ["."]
+
+[[bin]]
+name = "fuzz_decode"
+path = "fuzz_targets/fuzz_decode.rs"

fuzz/fuzz_targets/fuzz_decode.rs

@@ -0,0 +1,37 @@
+#![no_main]
+#[macro_use]
+extern crate libfuzzer_sys;
+extern crate parity_wasm;
+extern crate mktemp;
+
+use std::fs::File;
+use std::io::Write;
+use std::process::Command;
+
+
+fuzz_target!(|data: &[u8]| {
+    let seed = mktemp::Temp::new_file().unwrap();
+    let mut seedfile = File::create(seed.as_ref()).unwrap();
+    seedfile.write_all(data).unwrap();
+    seedfile.flush().unwrap();
+
+    let wasm = mktemp::Temp::new_file().unwrap();
+    let opt_fuzz = Command::new("wasm-opt")
+        .arg("--translate-to-fuzz")
+        .arg(seed.as_ref())
+        .arg("-o")
+        .arg(wasm.as_ref())
+        .output()
+        .unwrap();
+
+    assert!(
+        opt_fuzz.status.success(),
+        format!(
+            "wasm-opt failed with: {}",
+            String::from_utf8_lossy(&opt_fuzz.stderr)
+        )
+    );
+
+    let _module: parity_wasm::elements::Module = parity_wasm::deserialize_file(wasm.as_ref())
+        .unwrap();
+});