Initial commit of a fuzzer. Run with "cargo fuzz run simple_instantiate".

Used to discover issue #558.

We'll probably want to reconsider the default .gitignore of the artifacts and corpus directories. The fuzzer wastes a lot of time not having even a single exampel of a valid .wasm file to start with.

fuzz/.gitignore

@@ -0,0 +1,4 @@
+
+target
+corpus
+artifacts

fuzz/Cargo.toml

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+
+[package]
+name = "wasmer-fuzz"
+version = "0.0.1"
+authors = ["Automatically generated"]
+publish = false
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+wasmer-runtime = { path = "../lib/runtime" }
+libfuzzer-sys = { git = "https://github.com/rust-fuzz/libfuzzer-sys.git" }
+
+# Prevent this from interfering with workspaces
+[workspace]
+members = ["."]
+
+[[bin]]
+name = "simple_instantiate"
+path = "fuzz_targets/simple_instantiate.rs"

fuzz/fuzz_targets/simple_instantiate.rs

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+#![no_main]
+#[macro_use] extern crate libfuzzer_sys;
+extern crate wasmer_runtime;
+
+use wasmer_runtime::{
+    instantiate,
+    imports,
+};
+
+fuzz_target!(|data: &[u8]| {
+    let import_object = imports! {};
+    instantiate(data, &import_object);
+});