runtime/vm/dart_api_impl.cc

// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#include "include/dart_api.h"
#include "include/dart_native_api.h"

#include <memory>
#include <utility>

#include "lib/stacktrace.h"
#include "platform/assert.h"
#include "platform/unicode.h"
#include "vm/class_finalizer.h"
#include "vm/clustered_snapshot.h"
#include "vm/compilation_trace.h"
#include "vm/compiler/jit/compiler.h"
#include "vm/dart.h"
#include "vm/dart_api_impl.h"
#include "vm/dart_api_message.h"
#include "vm/dart_api_state.h"
#include "vm/dart_entry.h"
#include "vm/debugger.h"
#include "vm/dwarf.h"
#include "vm/elf.h"
#include "vm/exceptions.h"
#include "vm/flags.h"
#include "vm/growable_array.h"
#include "vm/heap/verifier.h"
#include "vm/image_snapshot.h"
#include "vm/isolate_reload.h"
#include "vm/kernel_isolate.h"
#include "vm/lockers.h"
#include "vm/message.h"
#include "vm/message_handler.h"
#include "vm/native_entry.h"
#include "vm/native_symbol.h"
#include "vm/object.h"
#include "vm/object_store.h"
#include "vm/os.h"
#include "vm/os_thread.h"
#include "vm/port.h"
#include "vm/profiler.h"
#include "vm/profiler_service.h"
#include "vm/program_visitor.h"
#include "vm/resolver.h"
#include "vm/reusable_handles.h"
#include "vm/service.h"
#include "vm/service_event.h"
#include "vm/service_isolate.h"
#include "vm/stack_frame.h"
#include "vm/symbols.h"
#include "vm/tags.h"
#include "vm/thread_registry.h"
#include "vm/uri.h"
#include "vm/version.h"

#if !defined(DART_PRECOMPILED_RUNTIME)
#include "vm/compiler/aot/precompiler.h"
#include "vm/kernel_loader.h"
#endif  // !defined(DART_PRECOMPILED_RUNTIME)

namespace dart {

// Facilitate quick access to the current zone once we have the current thread.
#define Z (T->zone())

DECLARE_FLAG(bool, print_class_table);
DECLARE_FLAG(bool, verify_handles);
#if defined(DEBUG) && !defined(DART_PRECOMPILED_RUNTIME)
DEFINE_FLAG(bool,
            check_function_fingerprints,
            true,
            "Check function fingerprints");
#endif  // defined(DEBUG) && !defined(DART_PRECOMPILED_RUNTIME).
DEFINE_FLAG(bool,
            verify_acquired_data,
            false,
            "Verify correct API acquire/release of typed data.");
DEFINE_FLAG(bool,
            dump_tables,
            false,
            "Dump common hash tables before snapshotting.");

#define CHECK_ERROR_HANDLE(error)                                              \
  {                                                                            \
    ErrorPtr err = (error);                                                    \
    if (err != Error::null()) {                                                \
      return Api::NewHandle(T, err);                                           \
    }                                                                          \
  }

ThreadLocalKey Api::api_native_key_ = kUnsetThreadLocalKey;
Dart_Handle Api::true_handle_ = NULL;
Dart_Handle Api::false_handle_ = NULL;
Dart_Handle Api::null_handle_ = NULL;
Dart_Handle Api::empty_string_handle_ = NULL;

const char* CanonicalFunction(const char* func) {
  if (strncmp(func, "dart::", 6) == 0) {
    return func + 6;
  } else {
    return func;
  }
}

#if defined(DEBUG)
// An object visitor which will iterate over all the function objects in the
// heap and check if the result type and parameter types are canonicalized
// or not. An assertion is raised if a type is not canonicalized.
class CheckFunctionTypesVisitor : public ObjectVisitor {
 public:
  explicit CheckFunctionTypesVisitor(Thread* thread)
      : classHandle_(Class::Handle(thread->zone())),
        funcHandle_(Function::Handle(thread->zone())),
        typeHandle_(AbstractType::Handle(thread->zone())) {}

  void VisitObject(ObjectPtr obj) {
    if (obj->IsFunction()) {
      funcHandle_ ^= obj;
      classHandle_ ^= funcHandle_.Owner();
      // Signature functions get created, but not canonicalized, when function
      // types get instantiated during run time type tests.
      if (funcHandle_.IsSignatureFunction()) {
        return;
      }
      // Verify that the result type of a function is canonical or a
      // TypeParameter.
      typeHandle_ ^= funcHandle_.result_type();
      ASSERT(typeHandle_.IsTypeParameter() || typeHandle_.IsCanonical());
      // Verify that the types in the function signature are all canonical or
      // a TypeParameter.
      const intptr_t num_parameters = funcHandle_.NumParameters();
      for (intptr_t i = 0; i < num_parameters; i++) {
        typeHandle_ = funcHandle_.ParameterTypeAt(i);
        ASSERT(typeHandle_.IsTypeParameter() || typeHandle_.IsCanonical());
      }
    }
  }

 private:
  Class& classHandle_;
  Function& funcHandle_;
  AbstractType& typeHandle_;
};
#endif  // #if defined(DEBUG).

static InstancePtr GetListInstance(Zone* zone, const Object& obj) {
  if (obj.IsInstance()) {
    ObjectStore* object_store = Isolate::Current()->object_store();
    const Type& list_rare_type =
        Type::Handle(zone, object_store->non_nullable_list_rare_type());
    ASSERT(!list_rare_type.IsNull());
    const Instance& instance = Instance::Cast(obj);
    const Class& obj_class = Class::Handle(zone, obj.clazz());
    if (Class::IsSubtypeOf(obj_class, Object::null_type_arguments(),
                           Nullability::kNonNullable, list_rare_type,
                           Heap::kNew)) {
      return instance.raw();
    }
  }
  return Instance::null();
}

static InstancePtr GetMapInstance(Zone* zone, const Object& obj) {
  if (obj.IsInstance()) {
    ObjectStore* object_store = Isolate::Current()->object_store();
    const Type& map_rare_type =
        Type::Handle(zone, object_store->non_nullable_map_rare_type());
    ASSERT(!map_rare_type.IsNull());
    const Instance& instance = Instance::Cast(obj);
    const Class& obj_class = Class::Handle(zone, obj.clazz());
    if (Class::IsSubtypeOf(obj_class, Object::null_type_arguments(),
                           Nullability::kNonNullable, map_rare_type,
                           Heap::kNew)) {
      return instance.raw();
    }
  }
  return Instance::null();
}

static bool IsCompiletimeErrorObject(Zone* zone, const Object& obj) {
#if defined(DART_PRECOMPILED_RUNTIME)
  // All compile-time errors were handled at snapshot generation time and
  // compiletime_error_class was removed.
  return false;
#else
  Isolate* I = Thread::Current()->isolate();
  const Class& error_class =
      Class::Handle(zone, I->object_store()->compiletime_error_class());
  ASSERT(!error_class.IsNull());
  return (obj.GetClassId() == error_class.id());
#endif
}

static bool GetNativeStringArgument(NativeArguments* arguments,
                                    int arg_index,
                                    Dart_Handle* str,
                                    void** peer) {
  ASSERT(peer != NULL);
  if (Api::StringGetPeerHelper(arguments, arg_index, peer)) {
    *str = NULL;
    return true;
  }
  Thread* thread = arguments->thread();
  ASSERT(thread == Thread::Current());
  *peer = NULL;
  REUSABLE_OBJECT_HANDLESCOPE(thread);
  Object& obj = thread->ObjectHandle();
  obj = arguments->NativeArgAt(arg_index);
  if (IsStringClassId(obj.GetClassId())) {
    ASSERT(thread->api_top_scope() != NULL);
    *str = Api::NewHandle(thread, obj.raw());
    return true;
  }
  if (obj.IsNull()) {
    *str = Api::Null();
    return true;
  }
  return false;
}

static bool GetNativeIntegerArgument(NativeArguments* arguments,
                                     int arg_index,
                                     int64_t* value) {
  ASSERT(value != NULL);
  return Api::GetNativeIntegerArgument(arguments, arg_index, value);
}

static bool GetNativeUnsignedIntegerArgument(NativeArguments* arguments,
                                             int arg_index,
                                             uint64_t* value) {
  ASSERT(value != NULL);
  int64_t arg_value = 0;
  if (Api::GetNativeIntegerArgument(arguments, arg_index, &arg_value)) {
    *value = static_cast<uint64_t>(arg_value);
    return true;
  }
  return false;
}

static bool GetNativeDoubleArgument(NativeArguments* arguments,
                                    int arg_index,
                                    double* value) {
  ASSERT(value != NULL);
  return Api::GetNativeDoubleArgument(arguments, arg_index, value);
}

static Dart_Handle GetNativeFieldsOfArgument(NativeArguments* arguments,
                                             int arg_index,
                                             int num_fields,
                                             intptr_t* field_values,
                                             const char* current_func) {
  ASSERT(field_values != NULL);
  if (Api::GetNativeFieldsOfArgument(arguments, arg_index, num_fields,
                                     field_values)) {
    return Api::Success();
  }
  Thread* thread = arguments->thread();
  ASSERT(thread == Thread::Current());
  REUSABLE_OBJECT_HANDLESCOPE(thread);
  Object& obj = thread->ObjectHandle();
  obj = arguments->NativeArgAt(arg_index);
  if (obj.IsNull()) {
    memset(field_values, 0, (num_fields * sizeof(field_values[0])));
    return Api::Success();
  }
  // We did not succeed in extracting the native fields report the
  // appropriate error.
  if (!obj.IsInstance()) {
    return Api::NewError(
        "%s expects argument at index '%d' to be of"
        " type Instance.",
        current_func, arg_index);
  }
  const Instance& instance = Instance::Cast(obj);
  int field_count = instance.NumNativeFields();
  ASSERT(num_fields != field_count);
  return Api::NewError("%s: expected %d 'num_fields' but was passed in %d.",
                       current_func, field_count, num_fields);
}

static ObjectPtr Send0Arg(const Instance& receiver, const String& selector) {
  const intptr_t kTypeArgsLen = 0;
  const intptr_t kNumArgs = 1;
  ArgumentsDescriptor args_desc(
      Array::Handle(ArgumentsDescriptor::NewBoxed(kTypeArgsLen, kNumArgs)));
  const Function& function =
      Function::Handle(Resolver::ResolveDynamic(receiver, selector, args_desc));
  if (function.IsNull()) {
    return ApiError::New(String::Handle(String::New("")));
  }
  const Array& args = Array::Handle(Array::New(kNumArgs));
  args.SetAt(0, receiver);
  return DartEntry::InvokeFunction(function, args);
}

static ObjectPtr Send1Arg(const Instance& receiver,
                          const String& selector,
                          const Instance& argument) {
  const intptr_t kTypeArgsLen = 0;
  const intptr_t kNumArgs = 2;
  ArgumentsDescriptor args_desc(
      Array::Handle(ArgumentsDescriptor::NewBoxed(kTypeArgsLen, kNumArgs)));
  const Function& function =
      Function::Handle(Resolver::ResolveDynamic(receiver, selector, args_desc));
  if (function.IsNull()) {
    return ApiError::New(String::Handle(String::New("")));
  }
  const Array& args = Array::Handle(Array::New(kNumArgs));
  args.SetAt(0, receiver);
  args.SetAt(1, argument);
  return DartEntry::InvokeFunction(function, args);
}

static const char* GetErrorString(Thread* thread, const Object& obj) {
  // This function requires an API scope to be present.
  if (obj.IsError()) {
    ASSERT(thread->api_top_scope() != NULL);
    const Error& error = Error::Cast(obj);
    const char* str = error.ToErrorCString();
    intptr_t len = strlen(str) + 1;
    char* str_copy = Api::TopScope(thread)->zone()->Alloc<char>(len);
    strncpy(str_copy, str, len);
    // Strip a possible trailing '\n'.
    if ((len > 1) && (str_copy[len - 2] == '\n')) {
      str_copy[len - 2] = '\0';
    }
    return str_copy;
  } else {
    return "";
  }
}

Dart_Handle Api::InitNewHandle(Thread* thread, ObjectPtr raw) {
  LocalHandles* local_handles = Api::TopScope(thread)->local_handles();
  ASSERT(local_handles != NULL);
  LocalHandle* ref = local_handles->AllocateHandle();
  ref->set_raw(raw);
  return ref->apiHandle();
}

Dart_Handle Api::NewHandle(Thread* thread, ObjectPtr raw) {
  if (raw == Object::null()) {
    return Null();
  }
  if (raw == Bool::True().raw()) {
    return True();
  }
  if (raw == Bool::False().raw()) {
    return False();
  }
  ASSERT(thread->execution_state() == Thread::kThreadInVM);
  return InitNewHandle(thread, raw);
}

ObjectPtr Api::UnwrapHandle(Dart_Handle object) {
#if defined(DEBUG)
  Thread* thread = Thread::Current();
  ASSERT(thread->execution_state() == Thread::kThreadInVM);
  ASSERT(thread->IsMutatorThread());
  ASSERT(thread->isolate() != NULL);
  ASSERT(!FLAG_verify_handles || thread->IsValidLocalHandle(object) ||
         thread->isolate()->group()->api_state()->IsActivePersistentHandle(
             reinterpret_cast<Dart_PersistentHandle>(object)) ||
         Dart::IsReadOnlyApiHandle(object));
  ASSERT(FinalizablePersistentHandle::raw_offset() == 0 &&
         PersistentHandle::raw_offset() == 0 && LocalHandle::raw_offset() == 0);
#endif
  return (reinterpret_cast<LocalHandle*>(object))->raw();
}

#define DEFINE_UNWRAP(type)                                                    \
  const type& Api::Unwrap##type##Handle(Zone* zone, Dart_Handle dart_handle) { \
    const Object& obj = Object::Handle(zone, Api::UnwrapHandle(dart_handle));  \
    if (obj.Is##type()) {                                                      \
      return type::Cast(obj);                                                  \
    }                                                                          \
    return type::Handle(zone);                                                 \
  }
CLASS_LIST_FOR_HANDLES(DEFINE_UNWRAP)
#undef DEFINE_UNWRAP

const String& Api::UnwrapStringHandle(const ReusableObjectHandleScope& reuse,
                                      Dart_Handle dart_handle) {
  Object& ref = reuse.Handle();
  ref = Api::UnwrapHandle(dart_handle);
  if (ref.IsString()) {
    return String::Cast(ref);
  }
  return Object::null_string();
}

const Instance& Api::UnwrapInstanceHandle(
    const ReusableObjectHandleScope& reuse,
    Dart_Handle dart_handle) {
  Object& ref = reuse.Handle();
  ref = Api::UnwrapHandle(dart_handle);
  if (ref.IsInstance()) {
    return Instance::Cast(ref);
  }
  return Object::null_instance();
}

Dart_Handle Api::CheckAndFinalizePendingClasses(Thread* thread) {
  Isolate* isolate = thread->isolate();
  if (!isolate->AllowClassFinalization()) {
    // Class finalization is blocked for the isolate. Do nothing.
    return Api::Success();
  }
  if (ClassFinalizer::ProcessPendingClasses()) {
    return Api::Success();
  }
  ASSERT(thread->sticky_error() != Object::null());
  return Api::NewHandle(thread, thread->sticky_error());
}

Dart_Isolate Api::CastIsolate(Isolate* isolate) {
  return reinterpret_cast<Dart_Isolate>(isolate);
}

Dart_IsolateGroup Api::CastIsolateGroup(IsolateGroup* isolate_group) {
  return reinterpret_cast<Dart_IsolateGroup>(isolate_group);
}

Dart_Handle Api::NewError(const char* format, ...) {
  Thread* T = Thread::Current();
  CHECK_API_SCOPE(T);
  CHECK_CALLBACK_STATE(T);
  // Ensure we transition safepoint state to VM if we are not already in
  // that state.
  TransitionToVM transition(T);
  HANDLESCOPE(T);

  va_list args;
  va_start(args, format);
  char* buffer = OS::VSCreate(Z, format, args);
  va_end(args);

  const String& message = String::Handle(Z, String::New(buffer));
  return Api::NewHandle(T, ApiError::New(message));
}

Dart_Handle Api::NewArgumentError(const char* format, ...) {
  Thread* T = Thread::Current();
  CHECK_API_SCOPE(T);
  CHECK_CALLBACK_STATE(T);
  // Ensure we transition safepoint state to VM if we are not already in
  // that state.
  TransitionToVM transition(T);
  HANDLESCOPE(T);

  va_list args;
  va_start(args, format);
  char* buffer = OS::VSCreate(Z, format, args);
  va_end(args);

  const String& message = String::Handle(Z, String::New(buffer));
  const Array& arguments = Array::Handle(Z, Array::New(1));
  arguments.SetAt(0, message);
  Object& error = Object::Handle(
      Z, DartLibraryCalls::InstanceCreate(
             Library::Handle(Z, Library::CoreLibrary()),
             Symbols::ArgumentError(), Symbols::Dot(), arguments));
  if (!error.IsError()) {
    error = UnhandledException::New(Instance::Cast(error), Instance::Handle());
  }
  return Api::NewHandle(T, error.raw());
}

Dart_Handle Api::AcquiredError(IsolateGroup* isolate_group) {
  ApiState* state = isolate_group->api_state();
  ASSERT(state != NULL);
  PersistentHandle* acquired_error_handle = state->AcquiredError();
  return reinterpret_cast<Dart_Handle>(acquired_error_handle);
}

bool Api::IsValid(Dart_Handle handle) {
  Isolate* isolate = Isolate::Current();
  Thread* thread = Thread::Current();
  ASSERT(thread->IsMutatorThread());
  CHECK_ISOLATE(isolate);

  // Check against all of the handles in the current isolate as well as the
  // read-only handles.
  return thread->IsValidHandle(handle) ||
         isolate->group()->api_state()->IsActivePersistentHandle(
             reinterpret_cast<Dart_PersistentHandle>(handle)) ||
         isolate->group()->api_state()->IsActiveWeakPersistentHandle(
             reinterpret_cast<Dart_WeakPersistentHandle>(handle)) ||
         Dart::IsReadOnlyApiHandle(handle) ||
         Dart::IsReadOnlyHandle(reinterpret_cast<uword>(handle));
}

ApiLocalScope* Api::TopScope(Thread* thread) {
  ASSERT(thread != NULL);
  ApiLocalScope* scope = thread->api_top_scope();
  ASSERT(scope != NULL);
  return scope;
}

void Api::Init() {
  if (api_native_key_ == kUnsetThreadLocalKey) {
    api_native_key_ = OSThread::CreateThreadLocal();
  }
  ASSERT(api_native_key_ != kUnsetThreadLocalKey);
}

static Dart_Handle InitNewReadOnlyApiHandle(ObjectPtr raw) {
  ASSERT(raw->ptr()->InVMIsolateHeap());
  LocalHandle* ref = Dart::AllocateReadOnlyApiHandle();
  ref->set_raw(raw);
  return ref->apiHandle();
}

void Api::InitHandles() {
  Isolate* isolate = Isolate::Current();
  ASSERT(isolate != NULL);
  ASSERT(isolate == Dart::vm_isolate());
  ApiState* state = isolate->group()->api_state();
  ASSERT(state != NULL);

  ASSERT(true_handle_ == NULL);
  true_handle_ = InitNewReadOnlyApiHandle(Bool::True().raw());

  ASSERT(false_handle_ == NULL);
  false_handle_ = InitNewReadOnlyApiHandle(Bool::False().raw());

  ASSERT(null_handle_ == NULL);
  null_handle_ = InitNewReadOnlyApiHandle(Object::null());

  ASSERT(empty_string_handle_ == NULL);
  empty_string_handle_ = InitNewReadOnlyApiHandle(Symbols::Empty().raw());
}

void Api::Cleanup() {
  true_handle_ = NULL;
  false_handle_ = NULL;
  null_handle_ = NULL;
  empty_string_handle_ = NULL;
}

bool Api::StringGetPeerHelper(NativeArguments* arguments,
                              int arg_index,
                              void** peer) {
  NoSafepointScope no_safepoint_scope;
  ObjectPtr raw_obj = arguments->NativeArgAt(arg_index);
  if (!raw_obj->IsHeapObject()) {
    return false;
  }
  intptr_t cid = raw_obj->GetClassId();
  if (cid == kExternalOneByteStringCid) {
    ExternalOneByteStringPtr raw_string =
        static_cast<ExternalOneByteStringPtr>(raw_obj);
    *peer = raw_string->ptr()->peer_;
    return true;
  }
  if (cid == kOneByteStringCid || cid == kTwoByteStringCid) {
    Isolate* isolate = arguments->thread()->isolate();
    *peer = isolate->heap()->GetPeer(raw_obj);
    return (*peer != 0);
  }
  if (cid == kExternalTwoByteStringCid) {
    ExternalTwoByteStringPtr raw_string =
        static_cast<ExternalTwoByteStringPtr>(raw_obj);
    *peer = raw_string->ptr()->peer_;
    return true;
  }
  return false;
}

bool Api::GetNativeReceiver(NativeArguments* arguments, intptr_t* value) {
  NoSafepointScope no_safepoint_scope;
  ObjectPtr raw_obj = arguments->NativeArg0();
  if (raw_obj->IsHeapObject()) {
    intptr_t cid = raw_obj->GetClassId();
    if (cid >= kNumPredefinedCids) {
      ASSERT(Instance::Cast(Object::Handle(raw_obj)).IsValidNativeIndex(0));
      TypedDataPtr native_fields = *reinterpret_cast<TypedDataPtr*>(
          ObjectLayout::ToAddr(raw_obj) + sizeof(ObjectLayout));
      if (native_fields == TypedData::null()) {
        *value = 0;
      } else {
        *value = *bit_cast<intptr_t*, uint8_t*>(native_fields->ptr()->data());
      }
      return true;
    }
  }
  return false;
}

bool Api::GetNativeBooleanArgument(NativeArguments* arguments,
                                   int arg_index,
                                   bool* value) {
  NoSafepointScope no_safepoint_scope;
  ObjectPtr raw_obj = arguments->NativeArgAt(arg_index);
  if (raw_obj->IsHeapObject()) {
    intptr_t cid = raw_obj->GetClassId();
    if (cid == kBoolCid) {
      *value = (raw_obj == Object::bool_true().raw());
      return true;
    }
    if (cid == kNullCid) {
      *value = false;
      return true;
    }
  }
  return false;
}

bool Api::GetNativeIntegerArgument(NativeArguments* arguments,
                                   int arg_index,
                                   int64_t* value) {
  NoSafepointScope no_safepoint_scope;
  ObjectPtr raw_obj = arguments->NativeArgAt(arg_index);
  if (raw_obj->IsHeapObject()) {
    intptr_t cid = raw_obj->GetClassId();
    if (cid == kMintCid) {
      *value = static_cast<MintPtr>(raw_obj)->ptr()->value_;
      return true;
    }
    return false;
  }
  *value = Smi::Value(static_cast<SmiPtr>(raw_obj));
  return true;
}

bool Api::GetNativeDoubleArgument(NativeArguments* arguments,
                                  int arg_index,
                                  double* value) {
  NoSafepointScope no_safepoint_scope;
  ObjectPtr raw_obj = arguments->NativeArgAt(arg_index);
  if (raw_obj->IsHeapObject()) {
    intptr_t cid = raw_obj->GetClassId();
    if (cid == kDoubleCid) {
      *value = static_cast<DoublePtr>(raw_obj)->ptr()->value_;
      return true;
    }
    if (cid == kMintCid) {
      *value =
          static_cast<double>(static_cast<MintPtr>(raw_obj)->ptr()->value_);
      return true;
    }
    return false;
  }
  *value = static_cast<double>(Smi::Value(static_cast<SmiPtr>(raw_obj)));
  return true;
}

bool Api::GetNativeFieldsOfArgument(NativeArguments* arguments,
                                    int arg_index,
                                    int num_fields,
                                    intptr_t* field_values) {
  NoSafepointScope no_safepoint_scope;
  ObjectPtr raw_obj = arguments->NativeArgAt(arg_index);
  if (raw_obj->IsHeapObject()) {
    intptr_t cid = raw_obj->GetClassId();
    if (cid >= kNumPredefinedCids) {
      TypedDataPtr native_fields = *reinterpret_cast<TypedDataPtr*>(
          ObjectLayout::ToAddr(raw_obj) + sizeof(ObjectLayout));
      if (native_fields == TypedData::null()) {
        memset(field_values, 0, (num_fields * sizeof(field_values[0])));
      } else if (num_fields == Smi::Value(native_fields->ptr()->length_)) {
        intptr_t* native_values =
            bit_cast<intptr_t*, uint8_t*>(native_fields->ptr()->data());
        memmove(field_values, native_values,
                (num_fields * sizeof(field_values[0])));
      }
      return true;
    }
  }
  return false;
}

void Api::SetWeakHandleReturnValue(NativeArguments* args,
                                   Dart_WeakPersistentHandle retval) {
  args->SetReturnUnsafe(FinalizablePersistentHandle::Cast(retval)->raw());
}

PersistentHandle* PersistentHandle::Cast(Dart_PersistentHandle handle) {
  ASSERT(IsolateGroup::Current()->api_state()->IsValidPersistentHandle(handle));
  return reinterpret_cast<PersistentHandle*>(handle);
}

FinalizablePersistentHandle* FinalizablePersistentHandle::Cast(
    Dart_WeakPersistentHandle handle) {
#if defined(DEBUG)
  ApiState* state = IsolateGroup::Current()->api_state();
  ASSERT(state->IsValidWeakPersistentHandle(handle));
#endif
  return reinterpret_cast<FinalizablePersistentHandle*>(handle);
}
FinalizablePersistentHandle* FinalizablePersistentHandle::Cast(
    Dart_FinalizableHandle handle) {
#if defined(DEBUG)
  ApiState* state = IsolateGroup::Current()->api_state();
  ASSERT(state->IsValidFinalizableHandle(handle));
#endif
  return reinterpret_cast<FinalizablePersistentHandle*>(handle);
}

void FinalizablePersistentHandle::Finalize(
    IsolateGroup* isolate_group,
    FinalizablePersistentHandle* handle) {
  if (!handle->raw()->IsHeapObject()) {
    return;  // Free handle.
  }
  void* peer = handle->peer();
  ApiState* state = isolate_group->api_state();
  ASSERT(state != NULL);

  ASSERT(handle->auto_delete());

  if (handle->callback_signature_ == CallbackSignature::kHandleFinalizer) {
    Dart_HandleFinalizer callback = handle->callback();
    ASSERT(callback != NULL);
    (*callback)(isolate_group->embedder_data(), peer);
  } else {
    Dart_WeakPersistentHandleFinalizer callback =
        handle->CallbackWeakFinalizer();
    ASSERT(callback != NULL);
    Dart_WeakPersistentHandle object = handle->ApiWeakPersistentHandle();
    (*callback)(isolate_group->embedder_data(), object, peer);
  }

  state->FreeWeakPersistentHandle(handle);
}

// --- Handles ---

DART_EXPORT bool Dart_IsError(Dart_Handle handle) {
  Thread* thread = Thread::Current();
  TransitionNativeToVM transition(thread);
  return Api::IsError(handle);
}

DART_EXPORT void Dart_KillIsolate(Dart_Isolate handle) {
  Isolate* isolate = reinterpret_cast<Isolate*>(handle);
  CHECK_ISOLATE(isolate);
  Isolate::KillIfExists(isolate, Isolate::kKillMsg);
}

DART_EXPORT bool Dart_IsApiError(Dart_Handle object) {
  Thread* thread = Thread::Current();
  TransitionNativeToVM transition(thread);
  return Api::ClassId(object) == kApiErrorCid;
}

DART_EXPORT bool Dart_IsUnhandledExceptionError(Dart_Handle object) {
  Thread* thread = Thread::Current();
  TransitionNativeToVM transition(thread);
  return Api::ClassId(object) == kUnhandledExceptionCid;
}

DART_EXPORT bool Dart_IsCompilationError(Dart_Handle object) {
  if (::Dart_IsUnhandledExceptionError(object)) {
    DARTSCOPE(Thread::Current());
    const UnhandledException& error =
        UnhandledException::Cast(Object::Handle(Z, Api::UnwrapHandle(object)));
    const Instance& exc = Instance::Handle(Z, error.exception());
    return IsCompiletimeErrorObject(Z, exc);
  }

  Thread* thread = Thread::Current();
  TransitionNativeToVM transition(thread);
  return Api::ClassId(object) == kLanguageErrorCid;
}

DART_EXPORT bool Dart_IsFatalError(Dart_Handle object) {
  Thread* thread = Thread::Current();
  TransitionNativeToVM transition(thread);
  return Api::ClassId(object) == kUnwindErrorCid;
}

DART_EXPORT const char* Dart_GetError(Dart_Handle handle) {
  DARTSCOPE(Thread::Current());
  API_TIMELINE_DURATION(T);
  const Object& obj = Object::Handle(Z, Api::UnwrapHandle(handle));
  return GetErrorString(T, obj);
}

DART_EXPORT bool Dart_ErrorHasException(Dart_Handle handle) {
  DARTSCOPE(Thread::Current());
  const Object& obj = Object::Handle(Z, Api::UnwrapHandle(handle));
  return obj.IsUnhandledException();
}

DART_EXPORT Dart_Handle Dart_ErrorGetException(Dart_Handle handle) {
  DARTSCOPE(Thread::Current());
  const Object& obj = Object::Handle(Z, Api::UnwrapHandle(handle));
  if (obj.IsUnhandledException()) {
    const UnhandledException& error = UnhandledException::Cast(obj);
    return Api::NewHandle(T, error.exception());
  } else if (obj.IsError()) {
    return Api::NewError("This error is not an unhandled exception error.");
  } else {
    return Api::NewError("Can only get exceptions from error handles.");
  }
}

DART_EXPORT Dart_Handle Dart_ErrorGetStackTrace(Dart_Handle handle) {
  DARTSCOPE(Thread::Current());
  const Object& obj = Object::Handle(Z, Api::UnwrapHandle(handle));
  if (obj.IsUnhandledException()) {
    const UnhandledException& error = UnhandledException::Cast(obj);
    return Api::NewHandle(T, error.stacktrace());
  } else if (obj.IsError()) {
    return Api::NewError("This error is not an unhandled exception error.");
  } else {
    return Api::NewError("Can only get stacktraces from error handles.");
  }
}

DART_EXPORT Dart_Handle Dart_NewApiError(const char* error) {
  DARTSCOPE(Thread::Current());
  CHECK_CALLBACK_STATE(T);

  const String& message = String::Handle(Z, String::New(error));
  return Api::NewHandle(T, ApiError::New(message));
}

DART_EXPORT Dart_Handle Dart_NewCompilationError(const char* error) {
  DARTSCOPE(Thread::Current());
  CHECK_CALLBACK_STATE(T);

  const String& message = String::Handle(Z, String::New(error));
  return Api::NewHandle(T, LanguageError::New(message));
}

DART_EXPORT Dart_Handle Dart_NewUnhandledExceptionError(Dart_Handle exception) {
  DARTSCOPE(Thread::Current());
  CHECK_CALLBACK_STATE(T);

  Instance& obj = Instance::Handle(Z);
  intptr_t class_id = Api::ClassId(exception);
  if ((class_id == kApiErrorCid) || (class_id == kLanguageErrorCid)) {
    const Object& excp = Object::Handle(Z, Api::UnwrapHandle(exception));
    obj = String::New(GetErrorString(T, excp));
  } else {
    obj = Api::UnwrapInstanceHandle(Z, exception).raw();
    if (obj.IsNull()) {
      RETURN_TYPE_ERROR(Z, exception, Instance);
    }
  }
  const StackTrace& stacktrace = StackTrace::Handle(Z);
  return Api::NewHandle(T, UnhandledException::New(obj, stacktrace));
}

DART_EXPORT void Dart_PropagateError(Dart_Handle handle) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  const Object& obj = Object::Handle(thread->zone(), Api::UnwrapHandle(handle));
  if (!obj.IsError()) {
    FATAL1(
        "%s expects argument 'handle' to be an error handle.  "
        "Did you forget to check Dart_IsError first?",
        CURRENT_FUNC);
  }
  if (thread->top_exit_frame_info() == 0) {
    // There are no dart frames on the stack so it would be illegal to
    // propagate an error here.
    FATAL("No Dart frames on stack, cannot propagate error.");
  }
  // Unwind all the API scopes till the exit frame before propagating.
  const Error* error;
  {
    // We need to preserve the error object across the destruction of zones
    // when the ApiScopes are unwound.  By using NoSafepointScope, we can ensure
    // that GC won't touch the raw error object before creating a valid
    // handle for it in the surviving zone.
    NoSafepointScope no_safepoint;
    ErrorPtr raw_error = Api::UnwrapErrorHandle(thread->zone(), handle).raw();
    thread->UnwindScopes(thread->top_exit_frame_info());
    // Note that thread's zone is different here than at the beginning of this
    // function.
    error = &Error::Handle(thread->zone(), raw_error);
  }
  Exceptions::PropagateError(*error);
  UNREACHABLE();
}

DART_EXPORT Dart_Handle Dart_ToString(Dart_Handle object) {
  DARTSCOPE(Thread::Current());
  const Object& obj = Object::Handle(Z, Api::UnwrapHandle(object));
  if (obj.IsString()) {
    return Api::NewHandle(T, obj.raw());
  } else if (obj.IsInstance()) {
    CHECK_CALLBACK_STATE(T);
    const Instance& receiver = Instance::Cast(obj);
    return Api::NewHandle(T, DartLibraryCalls::ToString(receiver));
  } else {
    CHECK_CALLBACK_STATE(T);
    // This is a VM internal object. Call the C++ method of printing.
    return Api::NewHandle(T, String::New(obj.ToCString()));
  }
}

DART_EXPORT bool Dart_IdentityEquals(Dart_Handle obj1, Dart_Handle obj2) {
  DARTSCOPE(Thread::Current());
  {
    NoSafepointScope no_safepoint_scope;
    if (Api::UnwrapHandle(obj1) == Api::UnwrapHandle(obj2)) {
      return true;
    }
  }
  const Object& object1 = Object::Handle(Z, Api::UnwrapHandle(obj1));
  const Object& object2 = Object::Handle(Z, Api::UnwrapHandle(obj2));
  if (object1.IsInstance() && object2.IsInstance()) {
    return Instance::Cast(object1).IsIdenticalTo(Instance::Cast(object2));
  }
  return false;
}

DART_EXPORT Dart_Handle
Dart_HandleFromPersistent(Dart_PersistentHandle object) {
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  CHECK_ISOLATE(isolate);
  ApiState* state = isolate->group()->api_state();
  ASSERT(state != NULL);
  TransitionNativeToVM transition(thread);
  NoSafepointScope no_safepoint_scope;
  PersistentHandle* ref = PersistentHandle::Cast(object);
  return Api::NewHandle(thread, ref->raw());
}

DART_EXPORT Dart_Handle
Dart_HandleFromWeakPersistent(Dart_WeakPersistentHandle object) {
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  CHECK_ISOLATE(isolate);
  ApiState* state = isolate->group()->api_state();
  ASSERT(state != NULL);
  TransitionNativeToVM transition(thread);
  NoSafepointScope no_safepoint_scope;
  FinalizablePersistentHandle* weak_ref =
      FinalizablePersistentHandle::Cast(object);
  return Api::NewHandle(thread, weak_ref->raw());
}

static Dart_Handle HandleFromFinalizable(Dart_FinalizableHandle object) {
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  CHECK_ISOLATE(isolate);
  ApiState* state = isolate->group()->api_state();
  ASSERT(state != NULL);
  TransitionNativeToVM transition(thread);
  NoSafepointScope no_safepoint_scope;
  FinalizablePersistentHandle* weak_ref =
      FinalizablePersistentHandle::Cast(object);
  return Api::NewHandle(thread, weak_ref->raw());
}

DART_EXPORT Dart_PersistentHandle Dart_NewPersistentHandle(Dart_Handle object) {
  DARTSCOPE(Thread::Current());
  Isolate* I = T->isolate();
  ApiState* state = I->group()->api_state();
  ASSERT(state != NULL);
  const Object& old_ref = Object::Handle(Z, Api::UnwrapHandle(object));
  PersistentHandle* new_ref = state->AllocatePersistentHandle();
  new_ref->set_raw(old_ref);
  return new_ref->apiHandle();
}

DART_EXPORT void Dart_SetPersistentHandle(Dart_PersistentHandle obj1,
                                          Dart_Handle obj2) {
  DARTSCOPE(Thread::Current());
  Isolate* I = T->isolate();
  ApiState* state = I->group()->api_state();
  ASSERT(state != NULL);
  ASSERT(state->IsValidPersistentHandle(obj1));
  const Object& obj2_ref = Object::Handle(Z, Api::UnwrapHandle(obj2));
  PersistentHandle* obj1_ref = PersistentHandle::Cast(obj1);
  obj1_ref->set_raw(obj2_ref);
}

static Dart_WeakPersistentHandle AllocateWeakPersistentHandle(
    Thread* thread,
    const Object& ref,
    void* peer,
    intptr_t external_allocation_size,
    Dart_WeakPersistentHandleFinalizer callback) {
  if (!ref.raw()->IsHeapObject()) {
    return NULL;
  }
  FinalizablePersistentHandle* finalizable_ref =
      FinalizablePersistentHandle::New(thread->isolate(), ref, peer, callback,
                                       external_allocation_size,
                                       /*auto_delete=*/true);
  return finalizable_ref->ApiWeakPersistentHandle();
}

static Dart_WeakPersistentHandle AllocateWeakPersistentHandle(
    Thread* thread,
    Dart_Handle object,
    void* peer,
    intptr_t external_allocation_size,
    Dart_WeakPersistentHandleFinalizer callback) {
  REUSABLE_OBJECT_HANDLESCOPE(thread);
  Object& ref = thread->ObjectHandle();
  ref = Api::UnwrapHandle(object);
  return AllocateWeakPersistentHandle(thread, ref, peer,
                                      external_allocation_size, callback);
}

static Dart_FinalizableHandle AllocateFinalizableHandle(
    Thread* thread,
    const Object& ref,
    void* peer,
    intptr_t external_allocation_size,
    Dart_HandleFinalizer callback) {
  if (!ref.raw()->IsHeapObject()) {
    return NULL;
  }

  FinalizablePersistentHandle* finalizable_ref =
      FinalizablePersistentHandle::New(thread->isolate(), ref, peer, callback,
                                       external_allocation_size,
                                       /*auto_delete=*/true);
  return finalizable_ref->ApiFinalizableHandle();
}

static Dart_FinalizableHandle AllocateFinalizableHandle(
    Thread* thread,
    Dart_Handle object,
    void* peer,
    intptr_t external_allocation_size,
    Dart_HandleFinalizer callback) {
  REUSABLE_OBJECT_HANDLESCOPE(thread);
  Object& ref = thread->ObjectHandle();
  ref = Api::UnwrapHandle(object);
  return AllocateFinalizableHandle(thread, ref, peer, external_allocation_size,
                                   callback);
}

DART_EXPORT Dart_WeakPersistentHandle
Dart_NewWeakPersistentHandle(Dart_Handle object,
                             void* peer,
                             intptr_t external_allocation_size,
                             Dart_WeakPersistentHandleFinalizer callback) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  if (callback == NULL) {
    return NULL;
  }
  TransitionNativeToVM transition(thread);

  return AllocateWeakPersistentHandle(thread, object, peer,
                                      external_allocation_size, callback);
}

DART_EXPORT Dart_FinalizableHandle
Dart_NewFinalizableHandle(Dart_Handle object,
                          void* peer,
                          intptr_t external_allocation_size,
                          Dart_HandleFinalizer callback) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  if (callback == nullptr) {
    return nullptr;
  }
  TransitionNativeToVM transition(thread);
  return AllocateFinalizableHandle(thread, object, peer,
                                   external_allocation_size, callback);
}

DART_EXPORT void Dart_UpdateExternalSize(Dart_WeakPersistentHandle object,
                                         intptr_t external_size) {
  IsolateGroup* isolate_group = IsolateGroup::Current();
  CHECK_ISOLATE_GROUP(isolate_group);
  NoSafepointScope no_safepoint_scope;
  ApiState* state = isolate_group->api_state();
  ASSERT(state != NULL);
  ASSERT(state->IsActiveWeakPersistentHandle(object));
  auto weak_ref = FinalizablePersistentHandle::Cast(object);
  weak_ref->UpdateExternalSize(external_size, isolate_group);
}

DART_EXPORT void Dart_UpdateFinalizableExternalSize(
    Dart_FinalizableHandle object,
    Dart_Handle strong_ref_to_object,
    intptr_t external_allocation_size) {
  if (!::Dart_IdentityEquals(strong_ref_to_object,
                             HandleFromFinalizable(object))) {
    FATAL1(
        "%s expects arguments 'object' and 'strong_ref_to_object' to point to "
        "the same object.",
        CURRENT_FUNC);
  }
  auto wph_object = reinterpret_cast<Dart_WeakPersistentHandle>(object);
  ::Dart_UpdateExternalSize(wph_object, external_allocation_size);
}

DART_EXPORT void Dart_DeletePersistentHandle(Dart_PersistentHandle object) {
  IsolateGroup* isolate_group = IsolateGroup::Current();
  CHECK_ISOLATE_GROUP(isolate_group);
  NoSafepointScope no_safepoint_scope;
  ApiState* state = isolate_group->api_state();
  ASSERT(state != NULL);
  ASSERT(state->IsActivePersistentHandle(object));
  PersistentHandle* ref = PersistentHandle::Cast(object);
  ASSERT(!state->IsProtectedHandle(ref));
  if (!state->IsProtectedHandle(ref)) {
    state->FreePersistentHandle(ref);
  }
}

DART_EXPORT void Dart_DeleteWeakPersistentHandle(
    Dart_WeakPersistentHandle object) {
  IsolateGroup* isolate_group = IsolateGroup::Current();
  CHECK_ISOLATE_GROUP(isolate_group);
  NoSafepointScope no_safepoint_scope;
  ApiState* state = isolate_group->api_state();
  ASSERT(state != NULL);
  ASSERT(state->IsActiveWeakPersistentHandle(object));
  auto weak_ref = FinalizablePersistentHandle::Cast(object);
  weak_ref->EnsureFreedExternal(isolate_group);
  state->FreeWeakPersistentHandle(weak_ref);
}

DART_EXPORT void Dart_DeleteFinalizableHandle(
    Dart_FinalizableHandle object,
    Dart_Handle strong_ref_to_object) {
  if (!::Dart_IdentityEquals(strong_ref_to_object,
                             HandleFromFinalizable(object))) {
    FATAL1(
        "%s expects arguments 'object' and 'strong_ref_to_object' to point to "
        "the same object.",
        CURRENT_FUNC);
  }

  auto wph_object = reinterpret_cast<Dart_WeakPersistentHandle>(object);

  ::Dart_DeleteWeakPersistentHandle(wph_object);
}

// --- Initialization and Globals ---

DART_EXPORT const char* Dart_VersionString() {
  return Version::String();
}

DART_EXPORT char* Dart_Initialize(Dart_InitializeParams* params) {
  if (params == NULL) {
    return Utils::StrDup(
        "Dart_Initialize: "
        "Dart_InitializeParams is null.");
  }

  if (params->version != DART_INITIALIZE_PARAMS_CURRENT_VERSION) {
    return Utils::StrDup(
        "Dart_Initialize: "
        "Invalid Dart_InitializeParams version.");
  }

  return Dart::Init(params->vm_snapshot_data, params->vm_snapshot_instructions,
                    params->create_group, params->initialize_isolate,
                    params->shutdown_isolate, params->cleanup_isolate,
                    params->cleanup_group, params->thread_exit,
                    params->file_open, params->file_read, params->file_write,
                    params->file_close, params->entropy_source,
                    params->get_service_assets, params->start_kernel_isolate,
                    params->code_observer);
}

DART_EXPORT char* Dart_Cleanup() {
  CHECK_NO_ISOLATE(Isolate::Current());
  return Dart::Cleanup();
}

DART_EXPORT char* Dart_SetVMFlags(int argc, const char** argv) {
  return Flags::ProcessCommandLineFlags(argc, argv);
}

DART_EXPORT bool Dart_IsVMFlagSet(const char* flag_name) {
  return Flags::IsSet(flag_name);
}

#if !defined(PRODUCT)
#define VM_METRIC_API(type, variable, name, unit)                              \
  DART_EXPORT int64_t Dart_VM##variable##Metric() {                            \
    return vm_metric_##variable.Value();                                       \
  }
VM_METRIC_LIST(VM_METRIC_API);
#undef VM_METRIC_API
#else  // !defined(PRODUCT)
#define VM_METRIC_API(type, variable, name, unit)                              \
  DART_EXPORT int64_t Dart_VM##variable##Metric() { return -1; }
VM_METRIC_LIST(VM_METRIC_API)
#undef VM_METRIC_API
#endif  // !defined(PRODUCT)

#define ISOLATE_GROUP_METRIC_API(type, variable, name, unit)                   \
  DART_EXPORT int64_t Dart_Isolate##variable##Metric(Dart_Isolate isolate) {   \
    if (isolate == nullptr) {                                                  \
      FATAL1("%s expects argument 'isolate' to be non-null.", CURRENT_FUNC);   \
    }                                                                          \
    Isolate* iso = reinterpret_cast<Isolate*>(isolate);                        \
    return iso->group()->Get##variable##Metric()->Value();                     \
  }
ISOLATE_GROUP_METRIC_LIST(ISOLATE_GROUP_METRIC_API)
#undef ISOLATE_GROUP_METRIC_API

#if !defined(PRODUCT)
#define ISOLATE_METRIC_API(type, variable, name, unit)                         \
  DART_EXPORT int64_t Dart_Isolate##variable##Metric(Dart_Isolate isolate) {   \
    if (isolate == NULL) {                                                     \
      FATAL1("%s expects argument 'isolate' to be non-null.", CURRENT_FUNC);   \
    }                                                                          \
    Isolate* iso = reinterpret_cast<Isolate*>(isolate);                        \
    return iso->Get##variable##Metric()->Value();                              \
  }
ISOLATE_METRIC_LIST(ISOLATE_METRIC_API)
#undef ISOLATE_METRIC_API
#else  // !defined(PRODUCT)
#define ISOLATE_METRIC_API(type, variable, name, unit)                         \
  DART_EXPORT int64_t Dart_Isolate##variable##Metric(Dart_Isolate isolate) {   \
    return -1;                                                                 \
  }
ISOLATE_METRIC_LIST(ISOLATE_METRIC_API)
#undef ISOLATE_METRIC_API
#endif  // !defined(PRODUCT)

// --- Isolates ---

static Dart_Isolate CreateIsolate(IsolateGroup* group,
                                  bool is_new_group,
                                  const char* name,
                                  void* isolate_data,
                                  char** error) {
  CHECK_NO_ISOLATE(Isolate::Current());

  auto source = group->source();
  Isolate* I = Dart::CreateIsolate(name, source->flags, group);
  if (I == NULL) {
    if (error != NULL) {
      *error = Utils::StrDup("Isolate creation failed");
    }
    return reinterpret_cast<Dart_Isolate>(NULL);
  }

  Thread* T = Thread::Current();
  bool success = false;
  {
    StackZone zone(T);
    HANDLESCOPE(T);
    // We enter an API scope here as InitializeIsolate could compile some
    // bootstrap library files which call out to a tag handler that may create
    // Api Handles when an error is encountered.
    T->EnterApiScope();
    const Error& error_obj = Error::Handle(
        Z, Dart::InitializeIsolate(
               source->snapshot_data, source->snapshot_instructions,
               source->kernel_buffer, source->kernel_buffer_size,
               is_new_group ? nullptr : group, isolate_data));
    if (error_obj.IsNull()) {
#if defined(DEBUG) && !defined(DART_PRECOMPILED_RUNTIME)
      if (FLAG_check_function_fingerprints && !FLAG_precompiled_mode) {
        Library::CheckFunctionFingerprints();
      }
#endif  // defined(DEBUG) && !defined(DART_PRECOMPILED_RUNTIME).
      success = true;
    } else if (error != NULL) {
      *error = Utils::StrDup(error_obj.ToErrorCString());
    }
    // We exit the API scope entered above.
    T->ExitApiScope();
  }

  if (success) {
    if (is_new_group) {
      I->heap()->InitGrowthControl();
    }
    // A Thread structure has been associated to the thread, we do the
    // safepoint transition explicitly here instead of using the
    // TransitionXXX scope objects as the reverse transition happens
    // outside this scope in Dart_ShutdownIsolate/Dart_ExitIsolate.
    T->set_execution_state(Thread::kThreadInNative);
    T->EnterSafepoint();
    if (error != NULL) {
      *error = NULL;
    }
    return Api::CastIsolate(I);
  }

  Dart::ShutdownIsolate();
  return reinterpret_cast<Dart_Isolate>(NULL);
}

static bool IsServiceOrKernelIsolateName(const char* name) {
  if (ServiceIsolate::NameEquals(name)) {
    ASSERT(!ServiceIsolate::Exists());
    return true;
  }
#if !defined(DART_PRECOMPILED_RUNTIME)
  if (KernelIsolate::NameEquals(name)) {
    ASSERT(!KernelIsolate::Exists());
    return true;
  }
#endif  // !defined(DART_PRECOMPILED_RUNTIME)
  return false;
}

Isolate* CreateWithinExistingIsolateGroupAOT(IsolateGroup* group,
                                             const char* name,
                                             char** error) {
#if defined(DART_PRECOMPILED_RUNTIME)
  API_TIMELINE_DURATION(Thread::Current());
  CHECK_NO_ISOLATE(Isolate::Current());

  auto spawning_group = group;

  Isolate* isolate = reinterpret_cast<Isolate*>(
      CreateIsolate(spawning_group, /*is_new_group=*/false, name,
                    /*isolate_data=*/nullptr, error));
  if (isolate == nullptr) return nullptr;

  auto source = spawning_group->source();
  ASSERT(isolate->source() == source);

  return isolate;
#else
  UNREACHABLE();
#endif
}

Isolate* CreateWithinExistingIsolateGroup(IsolateGroup* group,
                                          const char* name,
                                          char** error) {
#if !defined(DART_PRECOMPILED_RUNTIME)
  API_TIMELINE_DURATION(Thread::Current());
  CHECK_NO_ISOLATE(Isolate::Current());

  // During isolate start we'll make a temporary anonymous group from the same
  // [source]. Once the isolate has been fully loaded we will merge it's heap
  // into the shared heap.
  auto spawning_group = new IsolateGroup(group->shareable_source(),
                                         /*isolate_group_data=*/nullptr);
  IsolateGroup::RegisterIsolateGroup(spawning_group);
  spawning_group->CreateHeap(
      /*is_vm_isolate=*/false,
      IsServiceOrKernelIsolateName(group->source()->name));

  Isolate* isolate = reinterpret_cast<Isolate*>(
      CreateIsolate(spawning_group, /*is_new_group=*/false, name,
                    /*isolate_data=*/nullptr, error));
  if (isolate == nullptr) return nullptr;

  auto source = spawning_group->source();
  ASSERT(isolate->source() == source);

  if (source->script_kernel_buffer != nullptr) {
    Dart_EnterScope();
    {
      Thread* T = Thread::Current();
      TransitionNativeToVM transition(T);
      HANDLESCOPE(T);
      StackZone zone(T);

      // NOTE: We do not attach a finalizer for this object, because the
      // embedder will free it once the isolate group has shutdown.
      const auto& td = ExternalTypedData::Handle(ExternalTypedData::New(
          kExternalTypedDataUint8ArrayCid,
          const_cast<uint8_t*>(source->script_kernel_buffer),
          source->script_kernel_size, Heap::kOld));

      std::unique_ptr<kernel::Program> program =
          kernel::Program::ReadFromTypedData(td,
                                             const_cast<const char**>(error));
      if (program == nullptr) {
        UNIMPLEMENTED();
      }
      const Object& tmp =
          kernel::KernelLoader::LoadEntireProgram(program.get());

      // If the existing isolate could spawn with a root library we should be
      // able to do the same
      RELEASE_ASSERT(!tmp.IsNull() && tmp.IsLibrary());
      isolate->object_store()->set_root_library(Library::Cast(tmp));
    }
    Dart_ExitScope();
  }

  // If we are running in AppJIT training mode we'll have to remap class ids.
  if (auto permutation_map = group->source()->cid_permutation_map.get()) {
    Dart_EnterScope();
    {
      auto T = Thread::Current();
      TransitionNativeToVM transition(T);
      HANDLESCOPE(T);

      // Remap all class ids loaded atm (e.g. from snapshot) and do appropriate
      // re-hashing of constants and types.
      ClassFinalizer::RemapClassIds(permutation_map);
      // Types use cid's as part of their hashes.
      ClassFinalizer::RehashTypes();
      // Const objects use cid's as part of their hashes.
      isolate->RehashConstants();
    }
    Dart_ExitScope();
  }

  auto thread = Thread::Current();
  {
    TransitionNativeToVM native_to_vm(thread);

    // Ensure there are no helper threads running.
    BackgroundCompiler::Stop(isolate);
    isolate->heap()->WaitForMarkerTasks(thread);
    isolate->heap()->WaitForSweeperTasks(thread);
    RELEASE_ASSERT(isolate->heap()->old_space()->tasks() == 0);
  }

  Dart_ExitIsolate();
  {
    const bool kBypassSafepoint = false;
    Thread::EnterIsolateGroupAsHelper(group, Thread::kUnknownTask,
                                      kBypassSafepoint);
    ASSERT(group == IsolateGroup::Current());

    {
      auto thread = Thread::Current();

      // Prevent additions of new isolates to [group] until we're done.
      group->RunWithLockedGroup([&]() {
        // Ensure no other old space GC tasks are running and "occupy" the old
        // space.
        SafepointOperationScope safepoint_scope(thread);
        {
          auto old_space = group->heap()->old_space();
          MonitorLocker ml(old_space->tasks_lock());
          while (old_space->tasks() > 0) {
            ml.Wait();
          }
          old_space->set_tasks(1);
        }

        // Merge the heap from [spawning_group] to [group].
        group->heap()->MergeFrom(isolate->group()->heap());

        spawning_group->UnregisterIsolate(isolate);
        const bool shutdown_group =
            spawning_group->UnregisterIsolateDecrementCount(isolate);
        ASSERT(shutdown_group);

        isolate->isolate_group_ = group;
        group->RegisterIsolateLocked(isolate);
        isolate->class_table()->shared_class_table_ =
            group->shared_class_table();
        isolate->set_shared_class_table(group->shared_class_table());

        // Even though the mutator thread was descheduled, it will still
        // retain its [Thread] structure with valid isolate/isolate_group
        // pointers.
        // If GC happens before the mutator gets scheduled again, we have to
        // ensure the isolate group change is reflected in the threads
        // structure.
        ASSERT(isolate->mutator_thread() != nullptr);
        ASSERT(isolate->mutator_thread()->isolate_group() == spawning_group);
        isolate->mutator_thread()->isolate_group_ = group;

        // Allow other old space GC tasks to run again.
        {
          auto old_space = group->heap()->old_space();
          MonitorLocker ml(old_space->tasks_lock());
          ASSERT(old_space->tasks() == 1);
          old_space->set_tasks(0);
          ml.NotifyAll();
        }
      });
    }

    Thread::ExitIsolateGroupAsHelper(kBypassSafepoint);
  }

  spawning_group->Shutdown();

  Dart_EnterIsolate(Api::CastIsolate(isolate));
  ASSERT(Thread::Current()->isolate_group() == isolate->group());

  return isolate;
#else
  UNREACHABLE();
#endif
}

DART_EXPORT void Dart_IsolateFlagsInitialize(Dart_IsolateFlags* flags) {
  Isolate::FlagsInitialize(flags);
}

DART_EXPORT Dart_Isolate
Dart_CreateIsolateGroup(const char* script_uri,
                        const char* name,
                        const uint8_t* snapshot_data,
                        const uint8_t* snapshot_instructions,
                        Dart_IsolateFlags* flags,
                        void* isolate_group_data,
                        void* isolate_data,
                        char** error) {
  API_TIMELINE_DURATION(Thread::Current());

  Dart_IsolateFlags api_flags;
  if (flags == nullptr) {
    Isolate::FlagsInitialize(&api_flags);
    flags = &api_flags;
  }

  const char* non_null_name = name == nullptr ? "isolate" : name;
  std::unique_ptr<IsolateGroupSource> source(
      new IsolateGroupSource(script_uri, non_null_name, snapshot_data,
                             snapshot_instructions, nullptr, -1, *flags));
  auto group = new IsolateGroup(std::move(source), isolate_group_data);
  group->CreateHeap(
      /*is_vm_isolate=*/false, IsServiceOrKernelIsolateName(non_null_name));
  IsolateGroup::RegisterIsolateGroup(group);
  Dart_Isolate isolate = CreateIsolate(group, /*is_new_group=*/true,
                                       non_null_name, isolate_data, error);
  if (isolate != nullptr) {
    group->set_initial_spawn_successful();
  }
  return isolate;
}

DART_EXPORT Dart_Isolate
Dart_CreateIsolateGroupFromKernel(const char* script_uri,
                                  const char* name,
                                  const uint8_t* kernel_buffer,
                                  intptr_t kernel_buffer_size,
                                  Dart_IsolateFlags* flags,
                                  void* isolate_group_data,
                                  void* isolate_data,
                                  char** error) {
  API_TIMELINE_DURATION(Thread::Current());

  Dart_IsolateFlags api_flags;
  if (flags == nullptr) {
    Isolate::FlagsInitialize(&api_flags);
    flags = &api_flags;
  }

  const char* non_null_name = name == nullptr ? "isolate" : name;
  std::shared_ptr<IsolateGroupSource> source(
      new IsolateGroupSource(script_uri, non_null_name, nullptr, nullptr,
                             kernel_buffer, kernel_buffer_size, *flags));
  auto group = new IsolateGroup(source, isolate_group_data);
  IsolateGroup::RegisterIsolateGroup(group);
  group->CreateHeap(
      /*is_vm_isolate=*/false, IsServiceOrKernelIsolateName(non_null_name));
  Dart_Isolate isolate = CreateIsolate(group, /*is_new_group=*/true,
                                       non_null_name, isolate_data, error);
  if (isolate != nullptr) {
    group->set_initial_spawn_successful();
  }
  return isolate;
}

DART_EXPORT void Dart_ShutdownIsolate() {
  Thread* T = Thread::Current();
  Isolate* I = T->isolate();
  CHECK_ISOLATE(I);

  // The Thread structure is disassociated from the isolate, we do the
  // safepoint transition explicitly here instead of using the TransitionXXX
  // scope objects as the original transition happened outside this scope in
  // Dart_EnterIsolate/Dart_CreateIsolateGroup.
  ASSERT(T->execution_state() == Thread::kThreadInNative);
  T->ExitSafepoint();
  T->set_execution_state(Thread::kThreadInVM);

  I->WaitForOutstandingSpawns();

  // Release any remaining API scopes.
  ApiLocalScope* scope = T->api_top_scope();
  while (scope != NULL) {
    ApiLocalScope* previous = scope->previous();
    delete scope;
    scope = previous;
  }
  T->set_api_top_scope(NULL);

  {
    StackZone zone(T);
    HandleScope handle_scope(T);
    Dart::RunShutdownCallback();
  }
  Dart::ShutdownIsolate();
}

DART_EXPORT Dart_Isolate Dart_CurrentIsolate() {
  return Api::CastIsolate(Isolate::Current());
}

DART_EXPORT void* Dart_CurrentIsolateData() {
  Isolate* isolate = Isolate::Current();
  CHECK_ISOLATE(isolate);
  NoSafepointScope no_safepoint_scope;
  return isolate->init_callback_data();
}

DART_EXPORT void* Dart_IsolateData(Dart_Isolate isolate) {
  if (isolate == NULL) {
    FATAL1("%s expects argument 'isolate' to be non-null.", CURRENT_FUNC);
  }
  // TODO(http://dartbug.com/16615): Validate isolate parameter.
  return reinterpret_cast<Isolate*>(isolate)->init_callback_data();
}

DART_EXPORT Dart_IsolateGroup Dart_CurrentIsolateGroup() {
  return Api::CastIsolateGroup(IsolateGroup::Current());
}

DART_EXPORT void* Dart_CurrentIsolateGroupData() {
  IsolateGroup* isolate_group = IsolateGroup::Current();
  CHECK_ISOLATE_GROUP(isolate_group);
  NoSafepointScope no_safepoint_scope;
  return isolate_group->embedder_data();
}

DART_EXPORT void* Dart_IsolateGroupData(Dart_Isolate isolate) {
  if (isolate == NULL) {
    FATAL1("%s expects argument 'isolate' to be non-null.", CURRENT_FUNC);
  }
  // TODO(http://dartbug.com/16615): Validate isolate parameter.
  return reinterpret_cast<Isolate*>(isolate)->group()->embedder_data();
}

DART_EXPORT Dart_Handle Dart_DebugName() {
  DARTSCOPE(Thread::Current());
  Isolate* I = T->isolate();
  return Api::NewHandle(
      T, String::NewFormatted("(%" Pd64 ") '%s'",
                              static_cast<int64_t>(I->main_port()), I->name()));
}

DART_EXPORT const char* Dart_IsolateServiceId(Dart_Isolate isolate) {
  if (isolate == NULL) {
    FATAL1("%s expects argument 'isolate' to be non-null.", CURRENT_FUNC);
  }
  // TODO(http://dartbug.com/16615): Validate isolate parameter.
  Isolate* I = reinterpret_cast<Isolate*>(isolate);
  int64_t main_port = static_cast<int64_t>(I->main_port());
  return OS::SCreate(NULL, "isolates/%" Pd64, main_port);
}

DART_EXPORT void Dart_EnterIsolate(Dart_Isolate isolate) {
  CHECK_NO_ISOLATE(Isolate::Current());
  // TODO(http://dartbug.com/16615): Validate isolate parameter.
  Isolate* iso = reinterpret_cast<Isolate*>(isolate);
  if (!Thread::EnterIsolate(iso)) {
    FATAL(
        "Unable to Enter Isolate : "
        "Multiple mutators entering an isolate / "
        "Dart VM is shutting down");
  }
  // A Thread structure has been associated to the thread, we do the
  // safepoint transition explicitly here instead of using the
  // TransitionXXX scope objects as the reverse transition happens
  // outside this scope in Dart_ExitIsolate/Dart_ShutdownIsolate.
  Thread* T = Thread::Current();
  T->set_execution_state(Thread::kThreadInNative);
  T->EnterSafepoint();
}

DART_EXPORT void Dart_StartProfiling() {
#if !defined(PRODUCT)
  if (!FLAG_profiler) {
    FLAG_profiler = true;
    Profiler::Init();
  }
#endif  // !defined(PRODUCT)
}

DART_EXPORT void Dart_StopProfiling() {
#if !defined(PRODUCT)
  if (FLAG_profiler) {
    Profiler::Cleanup();
    FLAG_profiler = false;
  }
#endif  // !defined(PRODUCT)
}

DART_EXPORT void Dart_ThreadDisableProfiling() {
  OSThread* os_thread = OSThread::Current();
  if (os_thread == NULL) {
    return;
  }
  os_thread->DisableThreadInterrupts();
}

DART_EXPORT void Dart_ThreadEnableProfiling() {
  OSThread* os_thread = OSThread::Current();
  if (os_thread == NULL) {
    return;
  }
  os_thread->EnableThreadInterrupts();
}

DART_EXPORT void Dart_AddSymbols(const char* dso_name,
                                 void* buffer,
                                 intptr_t buffer_size) {
  NativeSymbolResolver::AddSymbols(dso_name, buffer, buffer_size);
}

DART_EXPORT bool Dart_WriteProfileToTimeline(Dart_Port main_port,
                                             char** error) {
#if defined(PRODUCT)
  return false;
#else
  if (!FLAG_profiler) {
    if (error != NULL) {
      *error = Utils::StrDup("The profiler is not running.");
    }
    return false;
  }

  const intptr_t kBufferLength = 512;
  char method[kBufferLength];

  // clang-format off
  intptr_t method_length = snprintf(method, kBufferLength, "{"
      "\"jsonrpc\": \"2.0\","
      "\"method\": \"_writeCpuProfileTimeline\","
      "\"id\": \"\","
      "\"params\": {"
      "  \"isolateId\": \"isolates/%" Pd64 "\","
      "  \"tags\": \"None\""
      "}"
  "}", main_port);
  // clang-format on
  ASSERT(method_length <= kBufferLength);

  char* response = NULL;
  intptr_t response_length;
  bool success = Dart_InvokeVMServiceMethod(
      reinterpret_cast<uint8_t*>(method), method_length,
      reinterpret_cast<uint8_t**>(&response), &response_length, error);
  free(response);
  return success;
#endif
}

DART_EXPORT bool Dart_ShouldPauseOnStart() {
#if defined(PRODUCT)
  return false;
#else
  Isolate* isolate = Isolate::Current();
  CHECK_ISOLATE(isolate);
  NoSafepointScope no_safepoint_scope;
  return isolate->message_handler()->should_pause_on_start();
#endif
}

DART_EXPORT void Dart_SetShouldPauseOnStart(bool should_pause) {
#if defined(PRODUCT)
  if (should_pause) {
    FATAL1("%s(true) is not supported in a PRODUCT build", CURRENT_FUNC);
  }
#else
  Isolate* isolate = Isolate::Current();
  CHECK_ISOLATE(isolate);
  NoSafepointScope no_safepoint_scope;
  if (isolate->is_runnable()) {
    FATAL1("%s expects the current isolate to not be runnable yet.",
           CURRENT_FUNC);
  }
  isolate->message_handler()->set_should_pause_on_start(should_pause);
#endif
}

DART_EXPORT bool Dart_IsPausedOnStart() {
#if defined(PRODUCT)
  return false;
#else
  Isolate* isolate = Isolate::Current();
  CHECK_ISOLATE(isolate);
  NoSafepointScope no_safepoint_scope;
  return isolate->message_handler()->is_paused_on_start();
#endif
}

DART_EXPORT void Dart_SetPausedOnStart(bool paused) {
#if defined(PRODUCT)
  if (paused) {
    FATAL1("%s(true) is not supported in a PRODUCT build", CURRENT_FUNC);
  }
#else
  Isolate* isolate = Isolate::Current();
  CHECK_ISOLATE(isolate);
  NoSafepointScope no_safepoint_scope;
  if (isolate->message_handler()->is_paused_on_start() != paused) {
    isolate->message_handler()->PausedOnStart(paused);
  }
#endif
}

DART_EXPORT bool Dart_ShouldPauseOnExit() {
#if defined(PRODUCT)
  return false;
#else
  Isolate* isolate = Isolate::Current();
  CHECK_ISOLATE(isolate);
  NoSafepointScope no_safepoint_scope;
  return isolate->message_handler()->should_pause_on_exit();
#endif
}

DART_EXPORT void Dart_SetShouldPauseOnExit(bool should_pause) {
#if defined(PRODUCT)
  if (should_pause) {
    FATAL1("%s(true) is not supported in a PRODUCT build", CURRENT_FUNC);
  }
#else
  Isolate* isolate = Isolate::Current();
  CHECK_ISOLATE(isolate);
  NoSafepointScope no_safepoint_scope;
  isolate->message_handler()->set_should_pause_on_exit(should_pause);
#endif
}

DART_EXPORT bool Dart_IsPausedOnExit() {
#if defined(PRODUCT)
  return false;
#else
  Isolate* isolate = Isolate::Current();
  CHECK_ISOLATE(isolate);
  NoSafepointScope no_safepoint_scope;
  return isolate->message_handler()->is_paused_on_exit();
#endif
}

DART_EXPORT void Dart_SetPausedOnExit(bool paused) {
#if defined(PRODUCT)
  if (paused) {
    FATAL1("%s(true) is not supported in a PRODUCT build", CURRENT_FUNC);
  }
#else
  Isolate* isolate = Isolate::Current();
  CHECK_ISOLATE(isolate);
  NoSafepointScope no_safepoint_scope;
  if (isolate->message_handler()->is_paused_on_exit() != paused) {
    isolate->message_handler()->PausedOnExit(paused);
  }
#endif
}

DART_EXPORT void Dart_SetStickyError(Dart_Handle error) {
  Thread* thread = Thread::Current();
  DARTSCOPE(thread);
  Isolate* isolate = thread->isolate();
  CHECK_ISOLATE(isolate);
  NoSafepointScope no_safepoint_scope;
  const Error& error_handle = Api::UnwrapErrorHandle(Z, error);
  if ((isolate->sticky_error() != Error::null()) &&
      (error_handle.raw() != Object::null())) {
    FATAL1("%s expects there to be no sticky error.", CURRENT_FUNC);
  }
  if (!error_handle.IsUnhandledException() &&
      (error_handle.raw() != Object::null())) {
    FATAL1("%s expects the error to be an unhandled exception error or null.",
           CURRENT_FUNC);
  }
  isolate->SetStickyError(error_handle.raw());
}

DART_EXPORT bool Dart_HasStickyError() {
  Thread* T = Thread::Current();
  Isolate* isolate = T->isolate();
  CHECK_ISOLATE(isolate);
  NoSafepointScope no_safepoint_scope;
  return isolate->sticky_error() != Error::null();
}

DART_EXPORT Dart_Handle Dart_GetStickyError() {
  Thread* T = Thread::Current();
  Isolate* I = T->isolate();
  CHECK_ISOLATE(I);
  {
    NoSafepointScope no_safepoint_scope;
    if (I->sticky_error() == Error::null()) {
      return Api::Null();
    }
  }
  TransitionNativeToVM transition(T);
  return Api::NewHandle(T, I->sticky_error());
}

DART_EXPORT void Dart_HintFreed(intptr_t size) {
  if (size < 0) {
    FATAL1("%s requires a non-negative size", CURRENT_FUNC);
  }
  Thread* T = Thread::Current();
  CHECK_ISOLATE(T->isolate());
  API_TIMELINE_BEGIN_END(T);
  TransitionNativeToVM transition(T);
  T->heap()->HintFreed(size);
}

DART_EXPORT void Dart_NotifyIdle(int64_t deadline) {
  Thread* T = Thread::Current();
  CHECK_ISOLATE(T->isolate());
  API_TIMELINE_BEGIN_END(T);
  TransitionNativeToVM transition(T);
  T->isolate()->group()->idle_time_handler()->NotifyIdle(deadline);
}

DART_EXPORT void Dart_NotifyLowMemory() {
  API_TIMELINE_BEGIN_END(Thread::Current());
  Isolate::NotifyLowMemory();
}

DART_EXPORT void Dart_ExitIsolate() {
  Thread* T = Thread::Current();
  CHECK_ISOLATE(T->isolate());
  // The Thread structure is disassociated from the isolate, we do the
  // safepoint transition explicitly here instead of using the TransitionXXX
  // scope objects as the original transition happened outside this scope in
  // Dart_EnterIsolate/Dart_CreateIsolateGroup.
  ASSERT(T->execution_state() == Thread::kThreadInNative);
  T->ExitSafepoint();
  T->set_execution_state(Thread::kThreadInVM);
  Thread::ExitIsolate();
}

#if !defined(DART_PRECOMPILED_RUNTIME)
static uint8_t* ApiReallocate(uint8_t* ptr,
                              intptr_t old_size,
                              intptr_t new_size) {
  return Api::TopScope(Thread::Current())
      ->zone()
      ->Realloc<uint8_t>(ptr, old_size, new_size);
}
#endif

DART_EXPORT Dart_Handle
Dart_CreateSnapshot(uint8_t** vm_snapshot_data_buffer,
                    intptr_t* vm_snapshot_data_size,
                    uint8_t** isolate_snapshot_data_buffer,
                    intptr_t* isolate_snapshot_data_size) {
#if defined(DART_PRECOMPILED_RUNTIME)
  return Api::NewError("Cannot create snapshots on an AOT runtime.");
#else
  DARTSCOPE(Thread::Current());
  API_TIMELINE_DURATION(T);
  Isolate* I = T->isolate();
  if (vm_snapshot_data_buffer != NULL && vm_snapshot_data_size == NULL) {
    RETURN_NULL_ERROR(vm_snapshot_data_size);
  }
  CHECK_NULL(isolate_snapshot_data_buffer);
  CHECK_NULL(isolate_snapshot_data_size);
  // Finalize all classes if needed.
  Dart_Handle state = Api::CheckAndFinalizePendingClasses(T);
  if (Api::IsError(state)) {
    return state;
  }
  BackgroundCompiler::Stop(I);

#if defined(DEBUG)
  I->heap()->CollectAllGarbage();
  {
    HeapIterationScope iteration(T);
    CheckFunctionTypesVisitor check_canonical(T);
    iteration.IterateObjects(&check_canonical);
  }
#endif  // #if defined(DEBUG)

  Symbols::Compact();

  FullSnapshotWriter writer(Snapshot::kFull, vm_snapshot_data_buffer,
                            isolate_snapshot_data_buffer, ApiReallocate,
                            NULL /* vm_image_writer */,
                            NULL /* isolate_image_writer */);
  writer.WriteFullSnapshot();
  if (vm_snapshot_data_buffer != NULL) {
    *vm_snapshot_data_size = writer.VmIsolateSnapshotSize();
  }
  *isolate_snapshot_data_size = writer.IsolateSnapshotSize();
  return Api::Success();
#endif
}

DART_EXPORT bool Dart_IsKernel(const uint8_t* buffer, intptr_t buffer_size) {
  if (buffer_size < 4) {
    return false;
  }
  return (buffer[0] == 0x90) && (buffer[1] == 0xab) && (buffer[2] == 0xcd) &&
         (buffer[3] == 0xef);
}

DART_EXPORT char* Dart_IsolateMakeRunnable(Dart_Isolate isolate) {
  CHECK_NO_ISOLATE(Isolate::Current());
  API_TIMELINE_DURATION(Thread::Current());
  if (isolate == NULL) {
    FATAL1("%s expects argument 'isolate' to be non-null.", CURRENT_FUNC);
  }
  // TODO(16615): Validate isolate parameter.
  Isolate* iso = reinterpret_cast<Isolate*>(isolate);
  const char* error;
  if (iso->object_store()->root_library() == Library::null()) {
    // The embedder should have called Dart_LoadScriptFromKernel by now.
    error = "Missing root library";
  } else {
    error = iso->MakeRunnable();
  }
  if (error != NULL) {
    return Utils::StrDup(error);
  }
  return NULL;
}

// --- Messages and Ports ---

DART_EXPORT void Dart_SetMessageNotifyCallback(
    Dart_MessageNotifyCallback message_notify_callback) {
  Isolate* isolate = Isolate::Current();
  CHECK_ISOLATE(isolate);

  {
    NoSafepointScope no_safepoint_scope;
    isolate->set_message_notify_callback(message_notify_callback);
  }

  if (message_notify_callback != nullptr && isolate->HasPendingMessages()) {
    ::Dart_ExitIsolate();

    // If a new handler gets installed and there are pending messages in the
    // queue (e.g. OOB messages for doing vm service work) we need to notify
    // the newly registered callback, otherwise the embedder might never get
    // notified about the pending messages.
    message_notify_callback(Api::CastIsolate(isolate));

    ::Dart_EnterIsolate(Api::CastIsolate(isolate));
  }
}

DART_EXPORT Dart_MessageNotifyCallback Dart_GetMessageNotifyCallback() {
  Isolate* isolate = Isolate::Current();
  CHECK_ISOLATE(isolate);
  NoSafepointScope no_safepoint_scope;
  return isolate->message_notify_callback();
}

struct RunLoopData {
  Monitor* monitor;
  bool done;
};

static void RunLoopDone(uword param) {
  RunLoopData* data = reinterpret_cast<RunLoopData*>(param);
  ASSERT(data->monitor != NULL);
  MonitorLocker ml(data->monitor);
  data->done = true;
  ml.Notify();
}

DART_EXPORT Dart_Handle Dart_RunLoop() {
  Isolate* I;
  {
    Thread* T = Thread::Current();
    I = T->isolate();
    CHECK_API_SCOPE(T);
    CHECK_CALLBACK_STATE(T);
  }
  API_TIMELINE_BEGIN_END(Thread::Current());
  // The message handler run loop does not expect to have a current isolate
  // so we exit the isolate here and enter it again after the runloop is done.
  ::Dart_ExitIsolate();
  {
    Monitor monitor;
    MonitorLocker ml(&monitor);
    RunLoopData data;
    data.monitor = &monitor;
    data.done = false;
    I->message_handler()->Run(I->group()->thread_pool(), NULL, RunLoopDone,
                              reinterpret_cast<uword>(&data));
    while (!data.done) {
      ml.Wait();
    }
  }
  ::Dart_EnterIsolate(Api::CastIsolate(I));
  if (I->sticky_error() != Object::null()) {
    Thread* T = Thread::Current();
    TransitionNativeToVM transition(T);
    return Api::NewHandle(T, I->StealStickyError());
  }
  if (FLAG_print_class_table) {
    HANDLESCOPE(Thread::Current());
    I->class_table()->Print();
  }
  return Api::Success();
}

DART_EXPORT Dart_Handle Dart_HandleMessage() {
  Thread* T = Thread::Current();
  Isolate* I = T->isolate();
  CHECK_API_SCOPE(T);
  CHECK_CALLBACK_STATE(T);
  API_TIMELINE_BEGIN_END_BASIC(T);
  TransitionNativeToVM transition(T);
  if (I->message_handler()->HandleNextMessage() != MessageHandler::kOK) {
    return Api::NewHandle(T, T->StealStickyError());
  }
  return Api::Success();
}

DART_EXPORT Dart_Handle Dart_WaitForEvent(int64_t timeout_millis) {
  Thread* T = Thread::Current();
  Isolate* I = T->isolate();
  CHECK_API_SCOPE(T);
  CHECK_CALLBACK_STATE(T);
  API_TIMELINE_BEGIN_END_BASIC(T);
  TransitionNativeToVM transition(T);
  if (I->message_notify_callback() != NULL) {
    return Api::NewError("waitForEventSync is not supported by this embedder");
  }
  Object& result =
      Object::Handle(Z, DartLibraryCalls::EnsureScheduleImmediate());
  if (result.IsError()) {
    return Api::NewHandle(T, result.raw());
  }

  // Drain the microtask queue. Propagate any errors to the entry frame.
  result = DartLibraryCalls::DrainMicrotaskQueue();
  if (result.IsError()) {
    // Persist the error across unwiding scopes before propagating.
    const Error* error;
    {
      NoSafepointScope no_safepoint;
      ErrorPtr raw_error = Error::Cast(result).raw();
      T->UnwindScopes(T->top_exit_frame_info());
      error = &Error::Handle(T->zone(), raw_error);
    }
    Exceptions::PropagateToEntry(*error);
    UNREACHABLE();
    return Api::NewError("Unreachable");
  }

  // Block to wait for messages and then handle them. Propagate any errors to
  // the entry frame.
  if (I->message_handler()->PauseAndHandleAllMessages(timeout_millis) !=
      MessageHandler::kOK) {
    // Persist the error across unwiding scopes before propagating.
    const Error* error;
    {
      NoSafepointScope no_safepoint;
      ErrorPtr raw_error = T->StealStickyError();
      T->UnwindScopes(T->top_exit_frame_info());
      error = &Error::Handle(T->zone(), raw_error);
    }
    Exceptions::PropagateToEntry(*error);
    UNREACHABLE();
    return Api::NewError("Unreachable");
  }
  return Api::Success();
}

DART_EXPORT bool Dart_HandleServiceMessages() {
#if defined(PRODUCT)
  return true;
#else
  Thread* T = Thread::Current();
  Isolate* I = T->isolate();
  CHECK_API_SCOPE(T);
  CHECK_CALLBACK_STATE(T);
  API_TIMELINE_DURATION(T);
  TransitionNativeToVM transition(T);
  ASSERT(I->GetAndClearResumeRequest() == false);
  MessageHandler::MessageStatus status =
      I->message_handler()->HandleOOBMessages();
  bool resume = I->GetAndClearResumeRequest();
  return (status != MessageHandler::kOK) || resume;
#endif
}

DART_EXPORT bool Dart_HasServiceMessages() {
#if defined(PRODUCT)
  return false;
#else
  Isolate* isolate = Isolate::Current();
  ASSERT(isolate);
  NoSafepointScope no_safepoint_scope;
  return isolate->message_handler()->HasOOBMessages();
#endif
}

DART_EXPORT bool Dart_HasLivePorts() {
  Isolate* isolate = Isolate::Current();
  ASSERT(isolate);
  NoSafepointScope no_safepoint_scope;
  return isolate->message_handler()->HasLivePorts();
}

DART_EXPORT bool Dart_Post(Dart_Port port_id, Dart_Handle handle) {
  DARTSCOPE(Thread::Current());
  API_TIMELINE_DURATION(T);
  NoSafepointScope no_safepoint_scope;
  if (port_id == ILLEGAL_PORT) {
    return false;
  }

  // Smis and null can be sent without serialization.
  ObjectPtr raw_obj = Api::UnwrapHandle(handle);
  if (ApiObjectConverter::CanConvert(raw_obj)) {
    return PortMap::PostMessage(
        Message::New(port_id, raw_obj, Message::kNormalPriority));
  }

  const Object& object = Object::Handle(Z, raw_obj);
  MessageWriter writer(false);
  return PortMap::PostMessage(
      writer.WriteMessage(object, port_id, Message::kNormalPriority));
}

DART_EXPORT Dart_Handle Dart_NewSendPort(Dart_Port port_id) {
  DARTSCOPE(Thread::Current());
  CHECK_CALLBACK_STATE(T);
  if (port_id == ILLEGAL_PORT) {
    return Api::NewError("%s: illegal port_id %" Pd64 ".", CURRENT_FUNC,
                         port_id);
  }
  return Api::NewHandle(T, SendPort::New(port_id));
}

DART_EXPORT Dart_Handle Dart_SendPortGetId(Dart_Handle port,
                                           Dart_Port* port_id) {
  DARTSCOPE(Thread::Current());
  CHECK_CALLBACK_STATE(T);
  API_TIMELINE_DURATION(T);
  const SendPort& send_port = Api::UnwrapSendPortHandle(Z, port);
  if (send_port.IsNull()) {
    RETURN_TYPE_ERROR(Z, port, SendPort);
  }
  if (port_id == NULL) {
    RETURN_NULL_ERROR(port_id);
  }
  *port_id = send_port.Id();
  return Api::Success();
}

DART_EXPORT Dart_Port Dart_GetMainPortId() {
  Isolate* isolate = Isolate::Current();
  CHECK_ISOLATE(isolate);
  return isolate->main_port();
}

// --- Scopes ----

DART_EXPORT void Dart_EnterScope() {
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  CHECK_ISOLATE(isolate);
  TransitionNativeToVM transition(thread);
  thread->EnterApiScope();
}

DART_EXPORT void Dart_ExitScope() {
  Thread* thread = Thread::Current();
  CHECK_API_SCOPE(thread);
  TransitionNativeToVM transition(thread);
  thread->ExitApiScope();
}

DART_EXPORT uint8_t* Dart_ScopeAllocate(intptr_t size) {
  Zone* zone;
  Thread* thread = Thread::Current();
  if (thread != NULL) {
    ApiLocalScope* scope = thread->api_top_scope();
    zone = scope->zone();
  } else {
    ApiNativeScope* scope = ApiNativeScope::Current();
    if (scope == NULL) return NULL;
    zone = scope->zone();
  }
  return reinterpret_cast<uint8_t*>(zone->AllocUnsafe(size));
}

// --- Objects ----

DART_EXPORT Dart_Handle Dart_Null() {
  ASSERT(Isolate::Current() != NULL);
  return Api::Null();
}

DART_EXPORT bool Dart_IsNull(Dart_Handle object) {
  TransitionNativeToVM transition(Thread::Current());
  return Api::UnwrapHandle(object) == Object::null();
}

DART_EXPORT Dart_Handle Dart_EmptyString() {
  ASSERT(Isolate::Current() != NULL);
  return Api::EmptyString();
}

DART_EXPORT Dart_Handle Dart_TypeDynamic() {
  DARTSCOPE(Thread::Current());
  CHECK_CALLBACK_STATE(T);
  API_TIMELINE_DURATION(T);
  return Api::NewHandle(T, Type::DynamicType());
}

DART_EXPORT Dart_Handle Dart_TypeVoid() {
  DARTSCOPE(Thread::Current());
  CHECK_CALLBACK_STATE(T);
  API_TIMELINE_DURATION(T);
  return Api::NewHandle(T, Type::VoidType());
}

DART_EXPORT Dart_Handle Dart_TypeNever() {
  DARTSCOPE(Thread::Current());
  CHECK_CALLBACK_STATE(T);
  API_TIMELINE_DURATION(T);
  return Api::NewHandle(T, Type::NeverType());
}

DART_EXPORT Dart_Handle Dart_ObjectEquals(Dart_Handle obj1,
                                          Dart_Handle obj2,
                                          bool* value) {
  DARTSCOPE(Thread::Current());
  CHECK_CALLBACK_STATE(T);
  const Instance& expected =
      Instance::CheckedHandle(Z, Api::UnwrapHandle(obj1));
  const Instance& actual = Instance::CheckedHandle(Z, Api::UnwrapHandle(obj2));
  const Object& result =
      Object::Handle(Z, DartLibraryCalls::Equals(expected, actual));
  if (result.IsBool()) {
    *value = Bool::Cast(result).value();
    return Api::Success();
  } else if (result.IsError()) {
    return Api::NewHandle(T, result.raw());
  } else {
    return Api::NewError("Expected boolean result from ==");
  }
}

// Assumes type is non-null.
static bool InstanceIsType(const Thread* thread,
                           const Instance& instance,
                           const Type& type) {
  ASSERT(!type.IsNull());
  CHECK_CALLBACK_STATE(thread);
  return instance.IsInstanceOf(type, Object::null_type_arguments(),
                               Object::null_type_arguments());
}

DART_EXPORT Dart_Handle Dart_ObjectIsType(Dart_Handle object,
                                          Dart_Handle type,
                                          bool* value) {
  DARTSCOPE(Thread::Current());

  const Type& type_obj = Api::UnwrapTypeHandle(Z, type);
  if (type_obj.IsNull()) {
    *value = false;
    RETURN_TYPE_ERROR(Z, type, Type);
  }
  if (!type_obj.IsFinalized()) {
    return Api::NewError(
        "%s expects argument 'type' to be a fully resolved type.",
        CURRENT_FUNC);
  }
  if (object == Api::Null()) {
    *value = false;
    return Api::Success();
  }
  const Instance& instance = Api::UnwrapInstanceHandle(Z, object);
  if (instance.IsNull()) {
    *value = false;
    RETURN_TYPE_ERROR(Z, object, Instance);
  }
  *value = InstanceIsType(T, instance, type_obj);
  return Api::Success();
}

DART_EXPORT bool Dart_IsInstance(Dart_Handle object) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  REUSABLE_OBJECT_HANDLESCOPE(thread);
  Object& ref = thread->ObjectHandle();
  ref = Api::UnwrapHandle(object);
  return ref.IsInstance();
}

DART_EXPORT bool Dart_IsNumber(Dart_Handle object) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return IsNumberClassId(Api::ClassId(object));
}

DART_EXPORT bool Dart_IsInteger(Dart_Handle object) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return IsIntegerClassId(Api::ClassId(object));
}

DART_EXPORT bool Dart_IsDouble(Dart_Handle object) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return Api::ClassId(object) == kDoubleCid;
}

DART_EXPORT bool Dart_IsBoolean(Dart_Handle object) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return Api::ClassId(object) == kBoolCid;
}

DART_EXPORT bool Dart_IsString(Dart_Handle object) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return IsStringClassId(Api::ClassId(object));
}

DART_EXPORT bool Dart_IsStringLatin1(Dart_Handle object) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return IsOneByteStringClassId(Api::ClassId(object));
}

DART_EXPORT bool Dart_IsExternalString(Dart_Handle object) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return IsExternalStringClassId(Api::ClassId(object));
}

DART_EXPORT bool Dart_IsList(Dart_Handle object) {
  DARTSCOPE(Thread::Current());
  if (IsBuiltinListClassId(Api::ClassId(object))) {
    return true;
  }

  const Object& obj = Object::Handle(Z, Api::UnwrapHandle(object));
  return GetListInstance(Z, obj) != Instance::null();
}

DART_EXPORT bool Dart_IsMap(Dart_Handle object) {
  DARTSCOPE(Thread::Current());
  const Object& obj = Object::Handle(Z, Api::UnwrapHandle(object));
  return GetMapInstance(Z, obj) != Instance::null();
}

DART_EXPORT bool Dart_IsLibrary(Dart_Handle object) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return Api::ClassId(object) == kLibraryCid;
}

DART_EXPORT bool Dart_IsType(Dart_Handle handle) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return Api::ClassId(handle) == kTypeCid;
}

DART_EXPORT bool Dart_IsFunction(Dart_Handle handle) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return Api::ClassId(handle) == kFunctionCid;
}

DART_EXPORT bool Dart_IsVariable(Dart_Handle handle) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return Api::ClassId(handle) == kFieldCid;
}

DART_EXPORT bool Dart_IsTypeVariable(Dart_Handle handle) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return Api::ClassId(handle) == kTypeParameterCid;
}

DART_EXPORT bool Dart_IsClosure(Dart_Handle object) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return Api::ClassId(object) == kClosureCid;
}

DART_EXPORT bool Dart_IsTearOff(Dart_Handle object) {
  DARTSCOPE(Thread::Current());
  API_TIMELINE_DURATION(T);
  const Object& obj = Object::Handle(Z, Api::UnwrapHandle(object));
  if (obj.IsClosure()) {
    const Closure& closure = Closure::Cast(obj);
    const Function& func = Function::Handle(Z, closure.function());
    return func.IsImplicitClosureFunction();
  }
  return false;
}

DART_EXPORT bool Dart_IsTypedData(Dart_Handle handle) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  intptr_t cid = Api::ClassId(handle);
  return IsTypedDataClassId(cid) || IsExternalTypedDataClassId(cid) ||
         IsTypedDataViewClassId(cid);
}

DART_EXPORT bool Dart_IsByteBuffer(Dart_Handle handle) {
  Thread* thread = Thread::Current();
  CHECK_ISOLATE(thread->isolate());
  TransitionNativeToVM transition(thread);
  return Api::ClassId(handle) == kByteBufferCid;
}

DART_EXPORT bool Dart_IsFuture(Dart_Handle handle) {
  DARTSCOPE(Thread::Current());
  API_TIMELINE_DURATION(T);
  const Object& obj = Object::Handle(Z, Api::UnwrapHandle(handle));
  if (obj.IsInstance()) {
    ObjectStore* object_store = T->isolate()->object_store();
    const Type& future_rare_type =
        Type::Handle(Z, object_store->non_nullable_future_rare_type());
    ASSERT(!future_rare_type.IsNull());
    const Class& obj_class = Class::Handle(Z, obj.clazz());
    bool is_future = Class::IsSubtypeOf(
        obj_class, Object::null_type_arguments(), Nullability::kNonNullable,
        future_rare_type, Heap::kNew);
    return is_future;
  }
  return false;
}

// --- Instances ----

DART_EXPORT Dart_Handle Dart_InstanceGetType(Dart_Handle instance) {
  DARTSCOPE(Thread::Current());
  API_TIMELINE_DURATION(T);
  Isolate* I = T->isolate();
  const Object& obj = Object::Handle(Z, Api::UnwrapHandle(instance));
  if (obj.IsNull()) {
    return Api::NewHandle(T, I->object_store()->null_type());
  }
  if (!obj.IsInstance()) {
    RETURN_TYPE_ERROR(Z, instance, Instance);
  }
  const AbstractType& type =
      AbstractType::Handle(Instance::Cast(obj).GetType(Heap::kNew));
  return Api::NewHandle(T, type.Canonicalize());
}

DART_EXPORT Dart_Handle Dart_FunctionName(Dart_Handle function) {
  DARTSCOPE(Thread::Current());
  const Function& func = Api::UnwrapFunctionHandle(Z, function);
  if (func.IsNull()) {
    RETURN_TYPE_ERROR(Z, function, Function);
  }
  return Api::NewHandle(T, func.UserVisibleName());
}

DART_EXPORT Dart_Handle Dart_ClassName(Dart_Handle cls_type) {
  DARTSCOPE(Thread::Current());
  const Type& type_obj = Api::UnwrapTypeHandle(Z, cls_type);
  if (type_obj.IsNull()) {
    RETURN_TYPE_ERROR(Z, cls_type, Type);
  }
  const Class& klass = Class::Handle(Z, type_obj.type_class());
  if (klass.IsNull()) {
    return Api::NewError(
        "cls_type must be a Type object which represents a Class.");
  }
  return Api::NewHandle(T, klass.UserVisibleName());
}

DART_EXPORT Dart_Handle Dart_FunctionOwner(Dart_Handle function) {
  DARTSCOPE(Thread::Current());
  const Function& func = Api::UnwrapFunctionHandle(Z, function);
  if (func.IsNull()) {
    RETURN_TYPE_ERROR(Z, function, Function);
  }
  if (func.IsNonImplicitClosureFunction()) {
    FunctionPtr parent_function = func.parent_function();
    return Api::NewHandle(T, parent_function);
  }
  const Class& owner = Class::Handle(Z, func.Owner());
  ASSERT(!owner.IsNull());
  if (owner.IsTopLevel()) {
// Top-level functions are implemented as members of a hidden class. We hide
// that class here and instead answer the library.
#if defined(DEBUG)
    const Library& lib = Library::Handle(Z, owner.library());
    if (lib.IsNull()) {
      ASSERT(owner.IsDynamicClass() || owner.IsVoidClass() ||
             owner.IsNeverClass());
    }
#endif
    return Api::NewHandle(T, owner.library());
  } else {
    return Api::NewHandle(T, owner.RareType());
  }
}

DART_EXPORT Dart_Handle Dart_FunctionIsStatic(Dart_Handle function,
                                              bool* is_static) {
  DARTSCOPE(Thread::Current());
  if (is_static == NULL) {
    RETURN_NULL_ERROR(is_static);
  }
  const Function& func = Api::UnwrapFunctionHandle(Z, function);
  if (func.IsNull()) {
    RETURN_TYPE_ERROR(Z, function, Function);
  }
  *is_static = func.is_static();
  return Api::Success();
}

DART_EXPORT Dart_Handle Dart_ClosureFunction(Dart_Handle closure) {
  DARTSCOPE(Thread::Current());
  const Instance& closure_obj = Api::UnwrapInstanceHandle(Z, closure);
  if (closure_obj.IsNull() || !closure_obj.IsClosure()) {
    RETURN_TYPE_ERROR(Z, closure, Instance);
  }

  ASSERT(ClassFinalizer::AllClassesFinalized());

  FunctionPtr rf = Closure::Cast(closure_obj).function();
  return Api::NewHandle(T, rf);
}

DART_EXPORT Dart_Handle Dart_ClassLibrary(Dart_Handle cls_type) {
  DARTSCOPE(Thread::Current());
  const Type& type_obj = Api::UnwrapTypeHandle(Z, cls_type);
  const Class& klass = Class::Handle(Z, type_obj.type_class());
  if (klass.IsNull()) {
    return Api::NewError(
        "cls_type must be a Type object which represents a Class.");
  }
  const Library& library = Library::Handle(klass.library());
  if (library.IsNull()) {
    return Dart_Null();
  }
  return Api::NewHandle(Thread::Current(), library.raw());
}

// --- Numbers, Integers and Doubles ----

DART_EXPORT Dart_Handle Dart_IntegerFitsIntoInt64(Dart_Handle integer,
                                                  bool* fits) {
  // Fast path for Smis and Mints.
  Thread* thread = Thread::Current();
  API_TIMELINE_DURATION(thread);
  Isolate* isolate = thread->isolate();
  CHECK_ISOLATE(isolate);
  if (Api::IsSmi(integer)) {
    *fits = true;
    return Api::Success();
  }
  // Slow path for mints and type error.
  DARTSCOPE(thread);
  if (Api::ClassId(integer) == kMintCid) {
    *fits = true;
    return Api::Success();
  }
  const Integer& int_obj = Api::UnwrapIntegerHandle(Z, integer);
  ASSERT(int_obj.IsNull());
  RETURN_TYPE_ERROR(Z, integer, Integer);
}

DART_EXPORT Dart_Handle Dart_IntegerFitsIntoUint64(Dart_Handle integer,
                                                   bool* fits) {
  // Fast path for Smis.
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  CHECK_ISOLATE(isolate);
  API_TIMELINE_DURATION(thread);
  if (Api::IsSmi(integer)) {
    *fits = (Api::SmiValue(integer) >= 0);
    return Api::Success();
  }
  // Slow path for Mints.
  DARTSCOPE(thread);
  const Integer& int_obj = Api::UnwrapIntegerHandle(Z, integer);
  if (int_obj.IsNull()) {
    RETURN_TYPE_ERROR(Z, integer, Integer);
  }
  ASSERT(int_obj.IsMint());
  *fits = !int_obj.IsNegative();
  return Api::Success();
}

DART_EXPORT Dart_Handle Dart_NewInteger(int64_t value) {
  // Fast path for Smis.
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  CHECK_ISOLATE(isolate);
  API_TIMELINE_DURATION(thread);
  DARTSCOPE(thread);
  CHECK_CALLBACK_STATE(thread);
  return Api::NewHandle(thread, Integer::New(value));
}

DART_EXPORT Dart_Handle Dart_NewIntegerFromUint64(uint64_t value) {
  DARTSCOPE(Thread::Current());
  CHECK_CALLBACK_STATE(T);
  API_TIMELINE_DURATION(T);
  if (Integer::IsValueInRange(value)) {
    return Api::NewHandle(T, Integer::NewFromUint64(value));
  }
  return Api::NewError("%s: Cannot create Dart integer from value %" Pu64,
                       CURRENT_FUNC, value);
}

DART_EXPORT Dart_Handle Dart_NewIntegerFromHexCString(const char* str) {
  DARTSCOPE(Thread::Current());
  CHECK_CALLBACK_STATE(T);
  API_TIMELINE_DURATION(T);
  const String& str_obj = String::Handle(Z, String::New(str));
  IntegerPtr integer = Integer::New(str_obj);
  if (integer == Integer::null()) {
    return Api::NewError("%s: Cannot create Dart integer from string %s",
                         CURRENT_FUNC, str);
  }
  return Api::NewHandle(T, integer);
}

DART_EXPORT Dart_Handle Dart_IntegerToInt64(Dart_Handle integer,
                                            int64_t* value) {
  // Fast path for Smis.
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  CHECK_ISOLATE(isolate);
  if (Api::IsSmi(integer)) {
    *value = Api::SmiValue(integer);
    return Api::Success();
  }
  // Slow path for Mints.
  DARTSCOPE(thread);
  const Integer& int_obj = Api::UnwrapIntegerHandle(Z, integer);
  if (int_obj.IsNull()) {
    RETURN_TYPE_ERROR(Z, integer, Integer);
  }
  ASSERT(int_obj.IsMint());
  *value = int_obj.AsInt64Value();
  return Api::Success();
}

DART_EXPORT Dart_Handle Dart_IntegerToUint64(Dart_Handle integer,
                                             uint64_t* value) {
  // Fast path for Smis.
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  CHECK_ISOLATE(isolate);
  if (Api::IsSmi(integer)) {
    intptr_t smi_value = Api::SmiValue(integer);
    if (smi_value >= 0) {
      *value = smi_value;
      return Api::Success();
    }
  }
  // Slow path for Mints.
  DARTSCOPE(thread);
  const Integer& int_obj = Api::UnwrapIntegerHandle(Z, integer);
  if (int_obj.IsNull()) {
    RETURN_TYPE_ERROR(Z, integer, Integer);
  }
  if (int_obj.IsSmi()) {
    ASSERT(int_obj.IsNegative());
  } else {
    ASSERT(int_obj.IsMint());
    if (!int_obj.IsNegative()) {
      *value = int_obj.AsInt64Value();
      return Api::Success();
    }
  }
  return Api::NewError("%s: Integer %s cannot be represented as a uint64_t.",
                       CURRENT_FUNC, int_obj.ToCString());
}

DART_EXPORT Dart_Handle Dart_IntegerToHexCString(Dart_Handle integer,
                                                 const char** value) {
  DARTSCOPE(Thread::Current());
  API_TIMELINE_DURATION(T);
  const Integer& int_obj = Api::UnwrapIntegerHandle(Z, integer);
  if (int_obj.IsNull()) {
    RETURN_TYPE_ERROR(Z, integer, Integer);
  }
  Zone* scope_zone = Api::TopScope(Thread::Current())->zone();
  *value = int_obj.ToHexCString(scope_zone);
  return Api::Success();
}

DART_EXPORT Dart_Handle Dart_NewDouble(double value) {
  DARTSCOPE(Thread::Current());
  CHECK_CALLBACK_STATE(T);
  return Api::NewHandle(T, Double::New(value));
}

DART_EXPORT Dart_Handle Dart_DoubleValue(Dart_Handle double_obj,
                                         double* value) {
  DARTSCOPE(Thread::Current());
  const Double& obj = Api::UnwrapDoubleHandle(Z, double_obj);
  if (obj.IsNull()) {
    RETURN_TYPE_ERROR(Z, double_obj, Double);
  }
  *value = obj.value();
  return Api::Success();
}

DART_EXPORT Dart_Handle Dart_GetStaticMethodClosure(Dart_Handle library,
                                                    Dart_Handle cls_type,
                                                    Dart_Handle function_name) {
  DARTSCOPE(Thread::Current());