v8/test/cctest/test-api-array-buffer.cc

// Copyright 2019 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 "src/api/api-inl.h"
#include "src/base/strings.h"
#include "src/objects/js-array-buffer-inl.h"
#include "test/cctest/test-api.h"

using ::v8::Array;
using ::v8::Context;
using ::v8::Local;
using ::v8::Value;

namespace {

void CheckDataViewIsDetached(v8::Local<v8::DataView> dv) {
  CHECK_EQ(0, static_cast<int>(dv->ByteLength()));
  CHECK_EQ(0, static_cast<int>(dv->ByteOffset()));
}

void CheckIsDetached(v8::Local<v8::TypedArray> ta) {
  CHECK_EQ(0, static_cast<int>(ta->ByteLength()));
  CHECK_EQ(0, static_cast<int>(ta->Length()));
  CHECK_EQ(0, static_cast<int>(ta->ByteOffset()));
}

void CheckIsTypedArrayVarDetached(const char* name) {
  v8::base::ScopedVector<char> source(1024);
  v8::base::SNPrintF(
      source, "%s.byteLength == 0 && %s.byteOffset == 0 && %s.length == 0",
      name, name, name);
  CHECK(CompileRun(source.begin())->IsTrue());
  v8::Local<v8::TypedArray> ta = CompileRun(name).As<v8::TypedArray>();
  CheckIsDetached(ta);
}

template <typename TypedArray, int kElementSize>
Local<TypedArray> CreateAndCheck(Local<v8::ArrayBuffer> ab, int byteOffset,
                                 int length) {
  v8::Local<TypedArray> ta = TypedArray::New(ab, byteOffset, length);
  CheckInternalFieldsAreZero<v8::ArrayBufferView>(ta);
  CHECK_EQ(byteOffset, static_cast<int>(ta->ByteOffset()));
  CHECK_EQ(length, static_cast<int>(ta->Length()));
  CHECK_EQ(length * kElementSize, static_cast<int>(ta->ByteLength()));
  return ta;
}

std::shared_ptr<v8::BackingStore> Externalize(Local<v8::ArrayBuffer> ab) {
  std::shared_ptr<v8::BackingStore> backing_store = ab->GetBackingStore();
  return backing_store;
}

std::shared_ptr<v8::BackingStore> Externalize(Local<v8::SharedArrayBuffer> ab) {
  std::shared_ptr<v8::BackingStore> backing_store = ab->GetBackingStore();
  return backing_store;
}

}  // namespace

THREADED_TEST(ArrayBuffer_ApiInternalToExternal) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);

  Local<v8::ArrayBuffer> ab = v8::ArrayBuffer::New(isolate, 1024);
  CheckInternalFieldsAreZero(ab);
  CHECK_EQ(1024, ab->ByteLength());
  CcTest::CollectAllGarbage();

  std::shared_ptr<v8::BackingStore> backing_store = Externalize(ab);
  CHECK_EQ(1024, backing_store->ByteLength());

  uint8_t* data = static_cast<uint8_t*>(backing_store->Data());
  CHECK_NOT_NULL(data);
  CHECK(env->Global()->Set(env.local(), v8_str("ab"), ab).FromJust());

  v8::Local<v8::Value> result = CompileRun("ab.byteLength");
  CHECK_EQ(1024, result->Int32Value(env.local()).FromJust());

  result = CompileRun(
      "var u8 = new Uint8Array(ab);"
      "u8[0] = 0xFF;"
      "u8[1] = 0xAA;"
      "u8.length");
  CHECK_EQ(1024, result->Int32Value(env.local()).FromJust());
  CHECK_EQ(0xFF, data[0]);
  CHECK_EQ(0xAA, data[1]);
  data[0] = 0xCC;
  data[1] = 0x11;
  result = CompileRun("u8[0] + u8[1]");
  CHECK_EQ(0xDD, result->Int32Value(env.local()).FromJust());
}

THREADED_TEST(ArrayBuffer_JSInternalToExternal) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);

  v8::Local<v8::Value> result = CompileRun(
      "var ab1 = new ArrayBuffer(2);"
      "var u8_a = new Uint8Array(ab1);"
      "u8_a[0] = 0xAA;"
      "u8_a[1] = 0xFF; u8_a.buffer");
  Local<v8::ArrayBuffer> ab1 = result.As<v8::ArrayBuffer>();
  CheckInternalFieldsAreZero(ab1);
  CHECK_EQ(2, ab1->ByteLength());
  std::shared_ptr<v8::BackingStore> backing_store = Externalize(ab1);

  result = CompileRun("ab1.byteLength");
  CHECK_EQ(2, result->Int32Value(env.local()).FromJust());
  result = CompileRun("u8_a[0]");
  CHECK_EQ(0xAA, result->Int32Value(env.local()).FromJust());
  result = CompileRun("u8_a[1]");
  CHECK_EQ(0xFF, result->Int32Value(env.local()).FromJust());
  result = CompileRun(
      "var u8_b = new Uint8Array(ab1);"
      "u8_b[0] = 0xBB;"
      "u8_a[0]");
  CHECK_EQ(0xBB, result->Int32Value(env.local()).FromJust());
  result = CompileRun("u8_b[1]");
  CHECK_EQ(0xFF, result->Int32Value(env.local()).FromJust());

  CHECK_EQ(2, backing_store->ByteLength());
  uint8_t* ab1_data = static_cast<uint8_t*>(backing_store->Data());
  CHECK_EQ(0xBB, ab1_data[0]);
  CHECK_EQ(0xFF, ab1_data[1]);
  ab1_data[0] = 0xCC;
  ab1_data[1] = 0x11;
  result = CompileRun("u8_a[0] + u8_a[1]");
  CHECK_EQ(0xDD, result->Int32Value(env.local()).FromJust());
}

THREADED_TEST(ArrayBuffer_DisableDetach) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);

  Local<v8::ArrayBuffer> ab = v8::ArrayBuffer::New(isolate, 100);
  CHECK(ab->IsDetachable());

  i::Handle<i::JSArrayBuffer> buf = v8::Utils::OpenHandle(*ab);
  buf->set_is_detachable(false);

  CHECK(!ab->IsDetachable());
}

THREADED_TEST(ArrayBuffer_DetachingApi) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);

  v8::Local<v8::ArrayBuffer> buffer = v8::ArrayBuffer::New(isolate, 1024);

  v8::Local<v8::Uint8Array> u8a =
      CreateAndCheck<v8::Uint8Array, 1>(buffer, 1, 1023);
  v8::Local<v8::Uint8ClampedArray> u8c =
      CreateAndCheck<v8::Uint8ClampedArray, 1>(buffer, 1, 1023);
  v8::Local<v8::Int8Array> i8a =
      CreateAndCheck<v8::Int8Array, 1>(buffer, 1, 1023);

  v8::Local<v8::Uint16Array> u16a =
      CreateAndCheck<v8::Uint16Array, 2>(buffer, 2, 511);
  v8::Local<v8::Int16Array> i16a =
      CreateAndCheck<v8::Int16Array, 2>(buffer, 2, 511);

  v8::Local<v8::Uint32Array> u32a =
      CreateAndCheck<v8::Uint32Array, 4>(buffer, 4, 255);
  v8::Local<v8::Int32Array> i32a =
      CreateAndCheck<v8::Int32Array, 4>(buffer, 4, 255);

  v8::Local<v8::Float32Array> f32a =
      CreateAndCheck<v8::Float32Array, 4>(buffer, 4, 255);
  v8::Local<v8::Float64Array> f64a =
      CreateAndCheck<v8::Float64Array, 8>(buffer, 8, 127);

  v8::Local<v8::DataView> dv = v8::DataView::New(buffer, 1, 1023);
  CheckInternalFieldsAreZero<v8::ArrayBufferView>(dv);
  CHECK_EQ(1, dv->ByteOffset());
  CHECK_EQ(1023, dv->ByteLength());

  Externalize(buffer);
  buffer->Detach();
  CHECK_EQ(0, buffer->ByteLength());
  CheckIsDetached(u8a);
  CheckIsDetached(u8c);
  CheckIsDetached(i8a);
  CheckIsDetached(u16a);
  CheckIsDetached(i16a);
  CheckIsDetached(u32a);
  CheckIsDetached(i32a);
  CheckIsDetached(f32a);
  CheckIsDetached(f64a);
  CheckDataViewIsDetached(dv);
}

THREADED_TEST(ArrayBuffer_DetachingScript) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);

  CompileRun(
      "var ab = new ArrayBuffer(1024);"
      "var u8a = new Uint8Array(ab, 1, 1023);"
      "var u8c = new Uint8ClampedArray(ab, 1, 1023);"
      "var i8a = new Int8Array(ab, 1, 1023);"
      "var u16a = new Uint16Array(ab, 2, 511);"
      "var i16a = new Int16Array(ab, 2, 511);"
      "var u32a = new Uint32Array(ab, 4, 255);"
      "var i32a = new Int32Array(ab, 4, 255);"
      "var f32a = new Float32Array(ab, 4, 255);"
      "var f64a = new Float64Array(ab, 8, 127);"
      "var dv = new DataView(ab, 1, 1023);");

  v8::Local<v8::ArrayBuffer> ab = CompileRun("ab").As<v8::ArrayBuffer>();
  v8::Local<v8::DataView> dv = CompileRun("dv").As<v8::DataView>();

  Externalize(ab);
  ab->Detach();
  CHECK_EQ(0, ab->ByteLength());
  CHECK_EQ(0, v8_run_int32value(v8_compile("ab.byteLength")));

  CheckIsTypedArrayVarDetached("u8a");
  CheckIsTypedArrayVarDetached("u8c");
  CheckIsTypedArrayVarDetached("i8a");
  CheckIsTypedArrayVarDetached("u16a");
  CheckIsTypedArrayVarDetached("i16a");
  CheckIsTypedArrayVarDetached("u32a");
  CheckIsTypedArrayVarDetached("i32a");
  CheckIsTypedArrayVarDetached("f32a");
  CheckIsTypedArrayVarDetached("f64a");

  {
    v8::TryCatch try_catch(isolate);
    CompileRun("dv.byteLength == 0 ");
    CHECK(try_catch.HasCaught());
  }

  {
    v8::TryCatch try_catch(isolate);
    CompileRun("dv.byteOffset == 0");
    CHECK(try_catch.HasCaught());
  }

  CheckDataViewIsDetached(dv);
}

THREADED_TEST(ArrayBuffer_ExternalizeEmpty) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);

  Local<v8::ArrayBuffer> ab = v8::ArrayBuffer::New(isolate, 2);
  CheckInternalFieldsAreZero(ab);
  CHECK_EQ(2, ab->ByteLength());

  // Externalize the buffer (taking ownership of the backing store memory).
  std::shared_ptr<v8::BackingStore> backing_store = Externalize(ab);

  Local<v8::Uint8Array> u8a = v8::Uint8Array::New(ab, 0, 0);
  // Calling Buffer() will materialize the ArrayBuffer (transitioning it from
  // on-heap to off-heap if need be). This should not affect whether it is
  // marked as is_external or not.
  USE(u8a->Buffer());

  CHECK_EQ(2, backing_store->ByteLength());
}

THREADED_TEST(SharedArrayBuffer_ApiInternalToExternal) {
  i::FLAG_harmony_sharedarraybuffer = true;
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);

  Local<v8::SharedArrayBuffer> ab = v8::SharedArrayBuffer::New(isolate, 1024);
  CheckInternalFieldsAreZero(ab);
  CHECK_EQ(1024, ab->ByteLength());
  CcTest::CollectAllGarbage();

  std::shared_ptr<v8::BackingStore> backing_store = Externalize(ab);

  CHECK_EQ(1024, backing_store->ByteLength());
  uint8_t* data = static_cast<uint8_t*>(backing_store->Data());
  CHECK_NOT_NULL(data);
  CHECK(env->Global()->Set(env.local(), v8_str("ab"), ab).FromJust());

  v8::Local<v8::Value> result = CompileRun("ab.byteLength");
  CHECK_EQ(1024, result->Int32Value(env.local()).FromJust());

  result = CompileRun(
      "var u8 = new Uint8Array(ab);"
      "u8[0] = 0xFF;"
      "u8[1] = 0xAA;"
      "u8.length");
  CHECK_EQ(1024, result->Int32Value(env.local()).FromJust());
  CHECK_EQ(0xFF, data[0]);
  CHECK_EQ(0xAA, data[1]);
  data[0] = 0xCC;
  data[1] = 0x11;
  result = CompileRun("u8[0] + u8[1]");
  CHECK_EQ(0xDD, result->Int32Value(env.local()).FromJust());
}

THREADED_TEST(SharedArrayBuffer_JSInternalToExternal) {
  i::FLAG_harmony_sharedarraybuffer = true;
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);

  v8::Local<v8::Value> result = CompileRun(
      "var ab1 = new SharedArrayBuffer(2);"
      "var u8_a = new Uint8Array(ab1);"
      "u8_a[0] = 0xAA;"
      "u8_a[1] = 0xFF; u8_a.buffer");
  Local<v8::SharedArrayBuffer> ab1 = result.As<v8::SharedArrayBuffer>();
  CheckInternalFieldsAreZero(ab1);
  CHECK_EQ(2, ab1->ByteLength());
  CHECK(!ab1->IsExternal());
  std::shared_ptr<v8::BackingStore> backing_store = Externalize(ab1);

  result = CompileRun("ab1.byteLength");
  CHECK_EQ(2, result->Int32Value(env.local()).FromJust());
  result = CompileRun("u8_a[0]");
  CHECK_EQ(0xAA, result->Int32Value(env.local()).FromJust());
  result = CompileRun("u8_a[1]");
  CHECK_EQ(0xFF, result->Int32Value(env.local()).FromJust());
  result = CompileRun(
      "var u8_b = new Uint8Array(ab1);"
      "u8_b[0] = 0xBB;"
      "u8_a[0]");
  CHECK_EQ(0xBB, result->Int32Value(env.local()).FromJust());
  result = CompileRun("u8_b[1]");
  CHECK_EQ(0xFF, result->Int32Value(env.local()).FromJust());

  CHECK_EQ(2, backing_store->ByteLength());
  uint8_t* ab1_data = static_cast<uint8_t*>(backing_store->Data());
  CHECK_EQ(0xBB, ab1_data[0]);
  CHECK_EQ(0xFF, ab1_data[1]);
  ab1_data[0] = 0xCC;
  ab1_data[1] = 0x11;
  result = CompileRun("u8_a[0] + u8_a[1]");
  CHECK_EQ(0xDD, result->Int32Value(env.local()).FromJust());
}

THREADED_TEST(SkipArrayBufferBackingStoreDuringGC) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);

  void* buffer = CcTest::array_buffer_allocator()->Allocate(100);
  // Make sure the pointer looks like a heap object
  uintptr_t address = reinterpret_cast<uintptr_t>(buffer) | i::kHeapObjectTag;
  void* store_ptr = reinterpret_cast<void*>(address);
  auto backing_store = v8::ArrayBuffer::NewBackingStore(
      store_ptr, 8, [](void*, size_t, void*) {}, nullptr);

  // Create ArrayBuffer with pointer-that-cannot-be-visited in the backing store
  Local<v8::ArrayBuffer> ab =
      v8::ArrayBuffer::New(isolate, std::move(backing_store));

  // Should not crash
  CcTest::CollectGarbage(i::NEW_SPACE);  // in survivor space now
  CcTest::CollectGarbage(i::NEW_SPACE);  // in old gen now
  CcTest::CollectAllGarbage();
  CcTest::CollectAllGarbage();

  // Should not move the pointer
  CHECK_EQ(ab->GetBackingStore()->Data(), store_ptr);
  CHECK_EQ(ab->Data(), store_ptr);

  CcTest::array_buffer_allocator()->Free(buffer, 100);
}

THREADED_TEST(SkipArrayBufferDuringScavenge) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);

  // Make sure the pointer looks like a heap object
  Local<v8::Object> tmp = v8::Object::New(isolate);
  uint8_t* store_ptr =
      reinterpret_cast<uint8_t*>(*reinterpret_cast<uintptr_t*>(*tmp));
  auto backing_store = v8::ArrayBuffer::NewBackingStore(
      store_ptr, 8, [](void*, size_t, void*) {}, nullptr);

  // Make `store_ptr` point to from space
  CcTest::CollectGarbage(i::NEW_SPACE);

  // Create ArrayBuffer with pointer-that-cannot-be-visited in the backing store
  Local<v8::ArrayBuffer> ab =
      v8::ArrayBuffer::New(isolate, std::move(backing_store));

  // Should not crash,
  // i.e. backing store pointer should not be treated as a heap object pointer
  CcTest::CollectGarbage(i::NEW_SPACE);  // in survivor space now
  CcTest::CollectGarbage(i::NEW_SPACE);  // in old gen now

  CHECK_EQ(ab->GetBackingStore()->Data(), store_ptr);
  CHECK_EQ(ab->Data(), store_ptr);
}

THREADED_TEST(Regress1006600) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);

  Local<v8::Value> ab = CompileRunChecked(isolate, "new ArrayBuffer()");
  for (int i = 0; i < v8::ArrayBuffer::kEmbedderFieldCount; i++) {
    CHECK_NULL(ab.As<v8::Object>()->GetAlignedPointerFromInternalField(i));
  }
}

THREADED_TEST(ArrayBuffer_NewBackingStore) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);
  std::shared_ptr<v8::BackingStore> backing_store =
      v8::ArrayBuffer::NewBackingStore(isolate, 100);
  CHECK(!backing_store->IsShared());
  Local<v8::ArrayBuffer> ab = v8::ArrayBuffer::New(isolate, backing_store);
  CHECK_EQ(backing_store.get(), ab->GetBackingStore().get());
  CHECK_EQ(backing_store->Data(), ab->Data());
}

THREADED_TEST(SharedArrayBuffer_NewBackingStore) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);
  std::shared_ptr<v8::BackingStore> backing_store =
      v8::SharedArrayBuffer::NewBackingStore(isolate, 100);
  CHECK(backing_store->IsShared());
  Local<v8::SharedArrayBuffer> ab =
      v8::SharedArrayBuffer::New(isolate, backing_store);
  CHECK_EQ(backing_store.get(), ab->GetBackingStore().get());
  CHECK_EQ(backing_store->Data(), ab->Data());
}

static void* backing_store_custom_data = nullptr;
static size_t backing_store_custom_length = 0;
static bool backing_store_custom_called = false;
const intptr_t backing_store_custom_deleter_data = 1234567;

static void BackingStoreCustomDeleter(void* data, size_t length,
                                      void* deleter_data) {
  CHECK(!backing_store_custom_called);
  CHECK_EQ(backing_store_custom_data, data);
  CHECK_EQ(backing_store_custom_length, length);
  CHECK_EQ(backing_store_custom_deleter_data,
           reinterpret_cast<intptr_t>(deleter_data));
  CcTest::array_buffer_allocator()->Free(data, length);
  backing_store_custom_called = true;
}

TEST(ArrayBuffer_NewBackingStore_CustomDeleter) {
  {
    // Create and destroy a backing store.
    backing_store_custom_called = false;
    backing_store_custom_data = CcTest::array_buffer_allocator()->Allocate(100);
    backing_store_custom_length = 100;
    v8::ArrayBuffer::NewBackingStore(
        backing_store_custom_data, backing_store_custom_length,
        BackingStoreCustomDeleter,
        reinterpret_cast<void*>(backing_store_custom_deleter_data));
  }
  CHECK(backing_store_custom_called);
}

TEST(SharedArrayBuffer_NewBackingStore_CustomDeleter) {
  {
    // Create and destroy a backing store.
    backing_store_custom_called = false;
    backing_store_custom_data = CcTest::array_buffer_allocator()->Allocate(100);
    backing_store_custom_length = 100;
    v8::SharedArrayBuffer::NewBackingStore(
        backing_store_custom_data, backing_store_custom_length,
        BackingStoreCustomDeleter,
        reinterpret_cast<void*>(backing_store_custom_deleter_data));
  }
  CHECK(backing_store_custom_called);
}

TEST(ArrayBuffer_NewBackingStore_EmptyDeleter) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);
  size_t size = 100;
  void* buffer = CcTest::array_buffer_allocator()->Allocate(size);
  std::unique_ptr<v8::BackingStore> backing_store =
      v8::ArrayBuffer::NewBackingStore(buffer, size,
                                       v8::BackingStore::EmptyDeleter, nullptr);
  uint64_t external_memory_before =
      isolate->AdjustAmountOfExternalAllocatedMemory(0);
  v8::ArrayBuffer::New(isolate, std::move(backing_store));
  uint64_t external_memory_after =
      isolate->AdjustAmountOfExternalAllocatedMemory(0);
  // The ArrayBuffer constructor does not increase the external memory counter.
  // The counter may decrease however if the allocation triggers GC.
  CHECK_GE(external_memory_before, external_memory_after);
  CcTest::array_buffer_allocator()->Free(buffer, size);
}

TEST(SharedArrayBuffer_NewBackingStore_EmptyDeleter) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);
  size_t size = 100;
  void* buffer = CcTest::array_buffer_allocator()->Allocate(size);
  std::unique_ptr<v8::BackingStore> backing_store =
      v8::SharedArrayBuffer::NewBackingStore(
          buffer, size, v8::BackingStore::EmptyDeleter, nullptr);
  uint64_t external_memory_before =
      isolate->AdjustAmountOfExternalAllocatedMemory(0);
  v8::SharedArrayBuffer::New(isolate, std::move(backing_store));
  uint64_t external_memory_after =
      isolate->AdjustAmountOfExternalAllocatedMemory(0);
  // The SharedArrayBuffer constructor does not increase the external memory
  // counter. The counter may decrease however if the allocation triggers GC.
  CHECK_GE(external_memory_before, external_memory_after);
  CcTest::array_buffer_allocator()->Free(buffer, size);
}

THREADED_TEST(BackingStore_NotShared) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);
  Local<v8::ArrayBuffer> ab = v8::ArrayBuffer::New(isolate, 8);
  CHECK(!ab->GetBackingStore()->IsShared());
  CHECK(!v8::ArrayBuffer::NewBackingStore(isolate, 8)->IsShared());
  backing_store_custom_called = false;
  backing_store_custom_data = CcTest::array_buffer_allocator()->Allocate(100);
  backing_store_custom_length = 100;
  CHECK(!v8::ArrayBuffer::NewBackingStore(
             backing_store_custom_data, backing_store_custom_length,
             BackingStoreCustomDeleter,
             reinterpret_cast<void*>(backing_store_custom_deleter_data))
             ->IsShared());
}

THREADED_TEST(BackingStore_Shared) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);
  Local<v8::SharedArrayBuffer> ab = v8::SharedArrayBuffer::New(isolate, 8);
  CHECK(ab->GetBackingStore()->IsShared());
  CHECK(v8::SharedArrayBuffer::NewBackingStore(isolate, 8)->IsShared());
  backing_store_custom_called = false;
  backing_store_custom_data = CcTest::array_buffer_allocator()->Allocate(100);
  backing_store_custom_length = 100;
  CHECK(v8::SharedArrayBuffer::NewBackingStore(
            backing_store_custom_data, backing_store_custom_length,
            BackingStoreCustomDeleter,
            reinterpret_cast<void*>(backing_store_custom_deleter_data))
            ->IsShared());
}

THREADED_TEST(ArrayBuffer_NewBackingStore_NullData) {
  // This test creates a BackingStore with nullptr as data. The test then
  // creates an ArrayBuffer and a TypedArray from this BackingStore. Writing
  // into that TypedArray at index 0 is expected to be a no-op, reading from
  // that TypedArray at index 0 should result in the default value '0'.
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  v8::HandleScope handle_scope(isolate);
  std::unique_ptr<v8::BackingStore> backing_store =
      v8::ArrayBuffer::NewBackingStore(nullptr, 0,
                                       v8::BackingStore::EmptyDeleter, nullptr);
  v8::Local<v8::ArrayBuffer> buffer =
      v8::ArrayBuffer::New(isolate, std::move(backing_store));

  CHECK(env->Global()->Set(env.local(), v8_str("buffer"), buffer).FromJust());

  v8::Local<v8::Value> result =
      CompileRunChecked(isolate,
                        "const view = new Int32Array(buffer);"
                        "view[0] = 14;"
                        "view[0];");
  CHECK_EQ(0, result->Int32Value(env.local()).FromJust());
}

class DummyAllocator final : public v8::ArrayBuffer::Allocator {
 public:
  DummyAllocator() : allocator_(NewDefaultAllocator()) {}

  ~DummyAllocator() override { CHECK_EQ(allocation_count(), 0); }

  void* Allocate(size_t length) override {
    allocation_count_++;
    return allocator_->Allocate(length);
  }
  void* AllocateUninitialized(size_t length) override {
    allocation_count_++;
    return allocator_->AllocateUninitialized(length);
  }
  void Free(void* data, size_t length) override {
    allocation_count_--;
    allocator_->Free(data, length);
  }

  uint64_t allocation_count() const { return allocation_count_; }

 private:
  std::unique_ptr<v8::ArrayBuffer::Allocator> allocator_;
  uint64_t allocation_count_ = 0;
};

TEST(BackingStore_HoldAllocatorAlive_UntilIsolateShutdown) {
  std::shared_ptr<DummyAllocator> allocator =
      std::make_shared<DummyAllocator>();
  std::weak_ptr<DummyAllocator> allocator_weak(allocator);

  v8::Isolate::CreateParams create_params;
  create_params.array_buffer_allocator_shared = allocator;
  v8::Isolate* isolate = v8::Isolate::New(create_params);
  isolate->Enter();

  allocator.reset();
  create_params.array_buffer_allocator_shared.reset();
  CHECK(!allocator_weak.expired());
  CHECK_EQ(allocator_weak.lock()->allocation_count(), 0);

  {
    // Create an ArrayBuffer and do not garbage collect it. This should make
    // the allocator be released automatically once the Isolate is disposed.
    v8::HandleScope handle_scope(isolate);
    v8::Context::Scope context_scope(Context::New(isolate));
    v8::ArrayBuffer::New(isolate, 8);

    // This should be inside the HandleScope, so that we can be sure that
    // the allocation is not garbage collected yet.
    CHECK(!allocator_weak.expired());
    CHECK_EQ(allocator_weak.lock()->allocation_count(), 1);
  }

  isolate->Exit();
  isolate->Dispose();
  CHECK(allocator_weak.expired());
}

TEST(BackingStore_HoldAllocatorAlive_AfterIsolateShutdown) {
  std::shared_ptr<DummyAllocator> allocator =
      std::make_shared<DummyAllocator>();
  std::weak_ptr<DummyAllocator> allocator_weak(allocator);

  v8::Isolate::CreateParams create_params;
  create_params.array_buffer_allocator_shared = allocator;
  v8::Isolate* isolate = v8::Isolate::New(create_params);
  isolate->Enter();

  allocator.reset();
  create_params.array_buffer_allocator_shared.reset();
  CHECK(!allocator_weak.expired());
  CHECK_EQ(allocator_weak.lock()->allocation_count(), 0);

  std::shared_ptr<v8::BackingStore> backing_store;
  {
    // Create an ArrayBuffer and do not garbage collect it. This should make
    // the allocator be released automatically once the Isolate is disposed.
    v8::HandleScope handle_scope(isolate);
    v8::Context::Scope context_scope(Context::New(isolate));
    v8::Local<v8::ArrayBuffer> ab = v8::ArrayBuffer::New(isolate, 8);
    backing_store = ab->GetBackingStore();
  }

  isolate->Exit();
  isolate->Dispose();
  CHECK(!allocator_weak.expired());
  CHECK_EQ(allocator_weak.lock()->allocation_count(), 1);
  backing_store.reset();
  CHECK(allocator_weak.expired());
}

class NullptrAllocator final : public v8::ArrayBuffer::Allocator {
 public:
  void* Allocate(size_t length) override {
    CHECK_EQ(length, 0);
    return nullptr;
  }
  void* AllocateUninitialized(size_t length) override {
    CHECK_EQ(length, 0);
    return nullptr;
  }
  void Free(void* data, size_t length) override { CHECK_EQ(data, nullptr); }
};

TEST(BackingStore_ReleaseAllocator_NullptrBackingStore) {
  std::shared_ptr<NullptrAllocator> allocator =
      std::make_shared<NullptrAllocator>();
  std::weak_ptr<NullptrAllocator> allocator_weak(allocator);

  v8::Isolate::CreateParams create_params;
  create_params.array_buffer_allocator_shared = allocator;
  v8::Isolate* isolate = v8::Isolate::New(create_params);
  isolate->Enter();

  allocator.reset();
  create_params.array_buffer_allocator_shared.reset();
  CHECK(!allocator_weak.expired());

  {
    std::shared_ptr<v8::BackingStore> backing_store =
        v8::ArrayBuffer::NewBackingStore(isolate, 0);
    // This should release a reference to the allocator, even though the
    // buffer is empty/nullptr.
    backing_store.reset();
  }

  isolate->Exit();
  isolate->Dispose();
  CHECK(allocator_weak.expired());
}

TEST(BackingStore_ReallocateExpand) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  std::unique_ptr<v8::BackingStore> backing_store =
      v8::ArrayBuffer::NewBackingStore(isolate, 10);
  {
    uint8_t* data = reinterpret_cast<uint8_t*>(
        reinterpret_cast<uintptr_t>(backing_store->Data()));
    for (uint8_t i = 0; i < 10; i++) {
      data[i] = i;
    }
  }
  std::unique_ptr<v8::BackingStore> new_backing_store =
      v8::BackingStore::Reallocate(isolate, std::move(backing_store), 20);
  CHECK_EQ(new_backing_store->ByteLength(), 20);
  CHECK(!new_backing_store->IsShared());
  {
    uint8_t* data = reinterpret_cast<uint8_t*>(
        reinterpret_cast<uintptr_t>(new_backing_store->Data()));
    for (uint8_t i = 0; i < 10; i++) {
      CHECK_EQ(data[i], i);
    }
    for (uint8_t i = 10; i < 20; i++) {
      CHECK_EQ(data[i], 0);
    }
  }
}

TEST(BackingStore_ReallocateShrink) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  std::unique_ptr<v8::BackingStore> backing_store =
      v8::ArrayBuffer::NewBackingStore(isolate, 20);
  {
    uint8_t* data = reinterpret_cast<uint8_t*>(backing_store->Data());
    for (uint8_t i = 0; i < 20; i++) {
      data[i] = i;
    }
  }
  std::unique_ptr<v8::BackingStore> new_backing_store =
      v8::BackingStore::Reallocate(isolate, std::move(backing_store), 10);
  CHECK_EQ(new_backing_store->ByteLength(), 10);
  CHECK(!new_backing_store->IsShared());
  {
    uint8_t* data = reinterpret_cast<uint8_t*>(new_backing_store->Data());
    for (uint8_t i = 0; i < 10; i++) {
      CHECK_EQ(data[i], i);
    }
  }
}

TEST(BackingStore_ReallocateNotShared) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  std::unique_ptr<v8::BackingStore> backing_store =
      v8::ArrayBuffer::NewBackingStore(isolate, 20);
  std::unique_ptr<v8::BackingStore> new_backing_store =
      v8::BackingStore::Reallocate(isolate, std::move(backing_store), 10);
  CHECK(!new_backing_store->IsShared());
}

TEST(BackingStore_ReallocateShared) {
  LocalContext env;
  v8::Isolate* isolate = env->GetIsolate();
  std::unique_ptr<v8::BackingStore> backing_store =
      v8::SharedArrayBuffer::NewBackingStore(isolate, 20);
  std::unique_ptr<v8::BackingStore> new_backing_store =
      v8::BackingStore::Reallocate(isolate, std::move(backing_store), 10);
  CHECK(new_backing_store->IsShared());
}