forked from mirrors/gecko-dev
5f737561c8
Adds a basic implementation without any optimisations. Differential Revision: https://phabricator.services.mozilla.com/D182480
106 lines
3.8 KiB
C++
106 lines
3.8 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 et cindent: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "mozilla/dom/ByteStreamHelpers.h"
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#include "mozilla/dom/ReadableByteStreamController.h"
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#include "js/ArrayBuffer.h"
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#include "js/RootingAPI.h"
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#include "js/experimental/TypedData.h"
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#include "mozilla/ErrorResult.h"
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namespace mozilla::dom {
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// https://streams.spec.whatwg.org/#transfer-array-buffer
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// As some parts of the specifcation want to use the abrupt completion value,
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// this function may leave a pending exception if it returns nullptr.
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JSObject* TransferArrayBuffer(JSContext* aCx, JS::Handle<JSObject*> aObject) {
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MOZ_ASSERT(JS::IsArrayBufferObject(aObject));
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// Step 1.
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MOZ_ASSERT(!JS::IsDetachedArrayBufferObject(aObject));
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// Step 3 (Reordered)
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size_t bufferLength = JS::GetArrayBufferByteLength(aObject);
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// Step 2 (Reordered)
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UniquePtr<void, JS::FreePolicy> bufferData{
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JS::StealArrayBufferContents(aCx, aObject)};
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// Step 4.
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if (!JS::DetachArrayBuffer(aCx, aObject)) {
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return nullptr;
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}
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// Step 5.
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return JS::NewArrayBufferWithContents(aCx, bufferLength,
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std::move(bufferData));
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}
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// https://streams.spec.whatwg.org/#can-transfer-array-buffer
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bool CanTransferArrayBuffer(JSContext* aCx, JS::Handle<JSObject*> aObject,
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ErrorResult& aRv) {
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// Step 1. Assert: Type(O) is Object. (Implicit in types)
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// Step 2. Assert: O has an [[ArrayBufferData]] internal slot.
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MOZ_ASSERT(JS::IsArrayBufferObject(aObject));
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// Step 3. If ! IsDetachedBuffer(O) is true, return false.
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if (JS::IsDetachedArrayBufferObject(aObject)) {
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return false;
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}
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// Step 4. If SameValue(O.[[ArrayBufferDetachKey]], undefined) is false,
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// return false.
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// Step 5. Return true.
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// Note: WASM memories are the only buffers that would qualify
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// as having an [[ArrayBufferDetachKey]] which is not undefined.
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bool hasDefinedArrayBufferDetachKey = false;
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if (!JS::HasDefinedArrayBufferDetachKey(aCx, aObject,
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&hasDefinedArrayBufferDetachKey)) {
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aRv.StealExceptionFromJSContext(aCx);
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return false;
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}
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return !hasDefinedArrayBufferDetachKey;
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}
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// https://streams.spec.whatwg.org/#abstract-opdef-cloneasuint8array
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JSObject* CloneAsUint8Array(JSContext* aCx, JS::Handle<JSObject*> aObject) {
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// Step 1. Assert: Type(O) is Object. Implicit.
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// Step 2. Assert: O has an [[ViewedArrayBuffer]] internal slot.
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MOZ_ASSERT(JS_IsArrayBufferViewObject(aObject));
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// Step 3. Assert: !IsDetachedBuffer(O.[[ViewedArrayBuffer]]) is false.
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bool isShared;
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JS::Rooted<JSObject*> viewedArrayBuffer(
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aCx, JS_GetArrayBufferViewBuffer(aCx, aObject, &isShared));
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if (!viewedArrayBuffer) {
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return nullptr;
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}
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MOZ_ASSERT(!JS::IsDetachedArrayBufferObject(viewedArrayBuffer));
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// Step 4. Let buffer be ?CloneArrayBuffer(O.[[ViewedArrayBuffer]],
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// O.[[ByteOffset]], O.[[ByteLength]], %ArrayBuffer%).
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size_t byteOffset = JS_GetTypedArrayByteOffset(aObject);
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size_t byteLength = JS_GetTypedArrayByteLength(aObject);
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JS::Rooted<JSObject*> buffer(
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aCx,
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JS::ArrayBufferClone(aCx, viewedArrayBuffer, byteOffset, byteLength));
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if (!buffer) {
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return nullptr;
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}
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// Step 5. Let array be ! Construct(%Uint8Array%, « buffer »).
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JS::Rooted<JSObject*> array(
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aCx, JS_NewUint8ArrayWithBuffer(aCx, buffer, 0,
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static_cast<int64_t>(byteLength)));
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if (!array) {
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return nullptr;
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}
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// Step 6. Return array.
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return array;
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}
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} // namespace mozilla::dom
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