[wasm] Write fuzzers for single wasm sections.

test/fuzzer/wasm-section-fuzzers.cc

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "test/fuzzer/wasm-section-fuzzers.h"
+
+#include "include/v8.h"
+#include "src/isolate.h"
+#include "src/wasm/encoder.h"
+#include "src/wasm/wasm-module.h"
+#include "src/zone.h"
+#include "test/cctest/wasm/wasm-module-runner.h"
+#include "test/fuzzer/fuzzer-support.h"
+
+using namespace v8::internal::wasm;
+
+int fuzz_wasm_section(WasmSection::Code section, const uint8_t* data,
+                      size_t size) {
+  v8_fuzzer::FuzzerSupport* support = v8_fuzzer::FuzzerSupport::Get();
+  v8::Isolate* isolate = support->GetIsolate();
+  v8::internal::Isolate* i_isolate =
+      reinterpret_cast<v8::internal::Isolate*>(isolate);
+
+  // Clear any pending exceptions from a prior run.
+  if (i_isolate->has_pending_exception()) {
+    i_isolate->clear_pending_exception();
+  }
+
+  v8::Isolate::Scope isolate_scope(isolate);
+  v8::HandleScope handle_scope(isolate);
+  v8::Context::Scope context_scope(support->GetContext());
+  v8::TryCatch try_catch(isolate);
+
+  v8::base::AccountingAllocator allocator;
+  v8::internal::Zone zone(&allocator);
+
+  ZoneBuffer buffer(&zone);
+  buffer.write_u32(kWasmMagic);
+  buffer.write_u32(kWasmVersion);
+  const char* name = WasmSection::getName(section);
+  size_t length = WasmSection::getNameLength(section);
+  buffer.write_size(length);  // Section name string size.
+  buffer.write(reinterpret_cast<const uint8_t*>(name), length);
+  buffer.write_u32v(static_cast<uint32_t>(size));
+  buffer.write(data, size);
+
+  ErrorThrower thrower(i_isolate, "decoder");
+
+  std::unique_ptr<const WasmModule> module(testing::DecodeWasmModuleForTesting(
+      i_isolate, &zone, thrower, buffer.begin(), buffer.end(), kWasmOrigin));
+
+  return 0;
+}