Add a library suitable for libfuzzer with a small unit test runner shell

test/fuzzer/fuzzer-support.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/fuzzer-support.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "include/libplatform/libplatform.h"
+
+namespace v8_fuzzer {
+
+namespace {
+
+FuzzerSupport* g_fuzzer_support = nullptr;
+
+void DeleteFuzzerSupport() {
+  if (g_fuzzer_support) {
+    delete g_fuzzer_support;
+    g_fuzzer_support = nullptr;
+  }
+}
+
+}  // namespace
+
+class FuzzerSupport::ArrayBufferAllocator : public v8::ArrayBuffer::Allocator {
+ public:
+  virtual void* Allocate(size_t length) {
+    void* data = AllocateUninitialized(length);
+    return data == NULL ? data : memset(data, 0, length);
+  }
+  virtual void* AllocateUninitialized(size_t length) { return malloc(length); }
+  virtual void Free(void* data, size_t) { free(data); }
+};
+
+FuzzerSupport::FuzzerSupport(int* argc, char*** argv) {
+  v8::V8::SetFlagsFromCommandLine(argc, *argv, true);
+  v8::V8::InitializeICU();
+  v8::V8::InitializeExternalStartupData((*argv)[0]);
+  platform_ = v8::platform::CreateDefaultPlatform();
+  v8::V8::InitializePlatform(platform_);
+  v8::V8::Initialize();
+
+  allocator_ = new ArrayBufferAllocator;
+  v8::Isolate::CreateParams create_params;
+  create_params.array_buffer_allocator = allocator_;
+  isolate_ = v8::Isolate::New(create_params);
+
+  {
+    v8::Isolate::Scope isolate_scope(isolate_);
+    v8::HandleScope handle_scope(isolate_);
+    context_.Reset(isolate_, v8::Context::New(isolate_));
+  }
+}
+
+FuzzerSupport::~FuzzerSupport() {
+  {
+    v8::Isolate::Scope isolate_scope(isolate_);
+    while (v8::platform::PumpMessageLoop(platform_, isolate_)) /* empty */
+      ;
+
+    v8::HandleScope handle_scope(isolate_);
+    context_.Reset();
+  }
+
+  isolate_->Dispose();
+  isolate_ = nullptr;
+
+  delete allocator_;
+  allocator_ = nullptr;
+
+  v8::V8::Dispose();
+  v8::V8::ShutdownPlatform();
+
+  delete platform_;
+  platform_ = nullptr;
+}
+
+// static
+FuzzerSupport* FuzzerSupport::Get() { return g_fuzzer_support; }
+
+v8::Isolate* FuzzerSupport::GetIsolate() { return isolate_; }
+
+v8::Local<v8::Context> FuzzerSupport::GetContext() {
+  v8::Isolate::Scope isolate_scope(isolate_);
+  v8::EscapableHandleScope handle_scope(isolate_);
+  v8::Local<v8::Context> context =
+      v8::Local<v8::Context>::New(isolate_, context_);
+  return handle_scope.Escape(context);
+}
+
+}  // namespace v8_fuzzer
+
+extern "C" int LLVMFuzzerInitialize(int* argc, char*** argv) {
+  v8_fuzzer::g_fuzzer_support = new v8_fuzzer::FuzzerSupport(argc, argv);
+  atexit(&v8_fuzzer::DeleteFuzzerSupport);
+  return 0;
+}