fuzz: adds validation target for maybe invalid module compilation (#879)

Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>

internal/integration_test/fuzz/wazerolib/validate.go

@@ -0,0 +1,40 @@
+package main
+
+import "C"
+import (
+	"context"
+	"reflect"
+	"unsafe"
+
+	"github.com/tetratelabs/wazero"
+)
+
+// validate accepts maybe-invalid Wasm module bytes and ensures that our validation phase works correctly
+// as well as the compiler doesn't panic during compilation!
+//
+//export validate
+func validate(binaryPtr uintptr, binarySize int) {
+	wasmBin := *(*[]byte)(unsafe.Pointer(&reflect.SliceHeader{
+		Data: binaryPtr,
+		Len:  binarySize,
+		Cap:  binarySize,
+	}))
+
+	failed := true
+	defer func() {
+		if failed {
+			// If the test fails, we save the binary and wat into testdata directory.
+			saveFailedBinary(wasmBin, "", "TestReRunFailedValidateCase")
+		}
+	}()
+
+	tryCompile(wasmBin)
+	failed = false
+}
+
+// Ensure that validation and compilation do not panic!
+func tryCompile(wasmBin []byte) {
+	ctx := context.Background()
+	compiler := wazero.NewRuntimeWithConfig(ctx, wazero.NewRuntimeConfigCompiler())
+	_, _ = compiler.CompileModule(ctx, wasmBin)
+}