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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mozilla/dom/ByteStreamHelpers.h"
#include "js/ArrayBuffer.h"
#include "js/RootingAPI.h"
#include "js/experimental/TypedData.h"
#include "mozilla/ErrorResult.h"
#include "mozilla/dom/ReadableByteStreamController.h"
namespace mozilla::dom {
// https://streams.spec.whatwg.org/#transfer-array-buffer
// As some parts of the specifcation want to use the abrupt completion value,
// this function may leave a pending exception if it returns nullptr.
//
// This can be called with a CCW to an ArrayBuffer Object as we handle the
// case explicitly.
JSObject* TransferArrayBuffer(JSContext* aCx, JS::Handle<JSObject*> aObject) {
JS::Rooted<JSObject*> unwrappedObj(aCx, JS::UnwrapArrayBuffer(aObject));
if (!unwrappedObj) {
js::ReportAccessDenied(aCx);
return nullptr;
}
size_t bufferLength = 0;
UniquePtr<void, JS::FreePolicy> bufferData;
{
JSAutoRealm ar(aCx, unwrappedObj);
// Step 1.
MOZ_ASSERT(!JS::IsDetachedArrayBufferObject(unwrappedObj));
// Step 3 (Reordered)
bufferLength = JS::GetArrayBufferByteLength(unwrappedObj);
// Step 2 (Reordered)
bufferData.reset(JS::StealArrayBufferContents(aCx, unwrappedObj));
// Step 4.
if (!JS::DetachArrayBuffer(aCx, unwrappedObj)) {
return nullptr;
}
}
// Step 5.
return JS::NewArrayBufferWithContents(aCx, bufferLength,
std::move(bufferData));
}
// https://streams.spec.whatwg.org/#can-transfer-array-buffer
bool CanTransferArrayBuffer(JSContext* aCx, JS::Handle<JSObject*> aObject,
ErrorResult& aRv) {
// Step 1. Assert: Type(O) is Object. (Implicit in types)
// Step 2. Assert: O has an [[ArrayBufferData]] internal slot.
MOZ_ASSERT(JS::IsArrayBufferObject(aObject));
// Step 3. If ! IsDetachedBuffer(O) is true, return false.
if (JS::IsDetachedArrayBufferObject(aObject)) {
return false;
}
// Step 4. If SameValue(O.[[ArrayBufferDetachKey]], undefined) is false,
// return false.
// Step 5. Return true.
// Note: WASM memories are the only buffers that would qualify
// as having an [[ArrayBufferDetachKey]] which is not undefined.
bool hasDefinedArrayBufferDetachKey = false;
if (!JS::HasDefinedArrayBufferDetachKey(aCx, aObject,
&hasDefinedArrayBufferDetachKey)) {
aRv.StealExceptionFromJSContext(aCx);
return false;
}
return !hasDefinedArrayBufferDetachKey;
}
// https://streams.spec.whatwg.org/#abstract-opdef-cloneasuint8array
JSObject* CloneAsUint8Array(JSContext* aCx, JS::Handle<JSObject*> aObject) {
// Step 1. Assert: Type(O) is Object. Implicit.
// Step 2. Assert: O has an [[ViewedArrayBuffer]] internal slot.
MOZ_ASSERT(JS_IsArrayBufferViewObject(aObject));
// Step 3. Assert: !IsDetachedBuffer(O.[[ViewedArrayBuffer]]) is false.
bool isShared;
JS::Rooted<JSObject*> viewedArrayBuffer(
aCx, JS_GetArrayBufferViewBuffer(aCx, aObject, &isShared));
if (!viewedArrayBuffer) {
return nullptr;
}
MOZ_ASSERT(!JS::IsDetachedArrayBufferObject(viewedArrayBuffer));
// Step 4. Let buffer be ?CloneArrayBuffer(O.[[ViewedArrayBuffer]],
// O.[[ByteOffset]], O.[[ByteLength]], %ArrayBuffer%).
size_t byteOffset = JS_GetTypedArrayByteOffset(aObject);
size_t byteLength = JS_GetTypedArrayByteLength(aObject);
JS::Rooted<JSObject*> buffer(
aCx,
JS::ArrayBufferClone(aCx, viewedArrayBuffer, byteOffset, byteLength));
if (!buffer) {
return nullptr;
}
// Step 5. Let array be ! Construct(%Uint8Array%, « buffer »).
JS::Rooted<JSObject*> array(
aCx, JS_NewUint8ArrayWithBuffer(aCx, buffer, 0,
static_cast<int64_t>(byteLength)));
if (!array) {
return nullptr;
}
// Step 6. Return array.
return array;
}
} // namespace mozilla::dom
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