Allow for accessing an ArrayBuffer contents without externalizing it

src/api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 6358 matching lines @@
   return Utils::OpenHandle(this)->is_external();
 }
 
 
 bool v8::ArrayBuffer::IsNeuterable() const {
   return Utils::OpenHandle(this)->is_neuterable();
 }
 
 
 v8::ArrayBuffer::Contents v8::ArrayBuffer::Externalize() {
-  i::Handle<i::JSArrayBuffer> obj = Utils::OpenHandle(this);
-  Utils::ApiCheck(!obj->is_external(),
-                  "v8::ArrayBuffer::Externalize",
+  i::Handle<i::JSArrayBuffer> self = Utils::OpenHandle(this);
+  Utils::ApiCheck(!self->is_external(), "v8::ArrayBuffer::Externalize",
                   "ArrayBuffer already externalized");
-  obj->set_is_external(true);
-  size_t byte_length = static_cast<size_t>(obj->byte_length()->Number());
+  self->set_is_external(true);
+  return GetContents();
+}
+
+
+v8::ArrayBuffer::Contents v8::ArrayBuffer::GetContents() {
+  i::Handle<i::JSArrayBuffer> self = Utils::OpenHandle(this);
+  size_t byte_length = static_cast<size_t>(self->byte_length()->Number());
   Contents contents;
-  contents.data_ = obj->backing_store();
+  contents.data_ = self->backing_store();
   contents.byte_length_ = byte_length;
   return contents;
 }
 
 
 void v8::ArrayBuffer::Neuter() {
   i::Handle<i::JSArrayBuffer> obj = Utils::OpenHandle(this);
   i::Isolate* isolate = obj->GetIsolate();
   Utils::ApiCheck(obj->is_external(),
                   "v8::ArrayBuffer::Neuter",
@@ skipping 17 matching lines @@
   LOG_API(i_isolate, "v8::ArrayBuffer::New(size_t)");
   ENTER_V8(i_isolate);
   i::Handle<i::JSArrayBuffer> obj =
       i_isolate->factory()->NewJSArrayBuffer();
   i::Runtime::SetupArrayBufferAllocatingData(i_isolate, obj, byte_length);
   return Utils::ToLocal(obj);
 }
 
 
 Local<ArrayBuffer> v8::ArrayBuffer::New(Isolate* isolate, void* data,
-                                        size_t byte_length) {
+                                        size_t byte_length,
+                                        ArrayBufferCreationMode mode) {
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   LOG_API(i_isolate, "v8::ArrayBuffer::New(void*, size_t)");
   ENTER_V8(i_isolate);
   i::Handle<i::JSArrayBuffer> obj =
       i_isolate->factory()->NewJSArrayBuffer();
-  i::Runtime::SetupArrayBuffer(i_isolate, obj, true, data, byte_length);
+  i::Runtime::SetupArrayBuffer(i_isolate, obj,
+                               mode == ArrayBufferCreationMode::kExternalized,
+                               data, byte_length);
   return Utils::ToLocal(obj);
 }
 
 
 Local<ArrayBuffer> v8::ArrayBufferView::Buffer() {
   i::Handle<i::JSArrayBufferView> obj = Utils::OpenHandle(this);
   i::Handle<i::JSArrayBuffer> buffer;
   if (obj->IsJSDataView()) {
     i::Handle<i::JSDataView> data_view(i::JSDataView::cast(*obj));
     DCHECK(data_view->buffer()->IsJSArrayBuffer());
@@ skipping 1702 matching lines @@
   Isolate* isolate = reinterpret_cast<Isolate*>(info.GetIsolate());
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 } }  // namespace v8::internal