Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2087 insertions, 0 deletions

diff --git a/dom/streams/ReadableByteStreamController.cpp b/dom/streams/ReadableByteStreamController.cpp
new file mode 100644
index 0000000000..1ce2ae4331
--- /dev/null
+++ b/dom/streams/ReadableByteStreamController.cpp
@@ -0,0 +1,2087 @@
+/* -*- 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/ReadableByteStreamController.h"
+
+#include "ReadIntoRequest.h"
+#include "js/ArrayBuffer.h"
+#include "js/ErrorReport.h"
+#include "js/Exception.h"
+#include "js/TypeDecls.h"
+#include "js/Value.h"
+#include "js/ValueArray.h"
+#include "js/experimental/TypedData.h"
+#include "js/friend/ErrorMessages.h"
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/HoldDropJSObjects.h"
+#include "mozilla/dom/ByteStreamHelpers.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/Promise-inl.h"
+#include "mozilla/dom/ReadableByteStreamControllerBinding.h"
+#include "mozilla/dom/ReadableStream.h"
+#include "mozilla/dom/ReadableStreamBYOBReader.h"
+#include "mozilla/dom/ReadableStreamBYOBRequest.h"
+#include "mozilla/dom/ReadableStreamController.h"
+#include "mozilla/dom/ReadableStreamDefaultController.h"
+#include "mozilla/dom/ReadableStreamDefaultReader.h"
+#include "mozilla/dom/ReadableStreamGenericReader.h"
+#include "mozilla/dom/ToJSValue.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/UnderlyingSourceCallbackHelpers.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsIGlobalObject.h"
+#include "nsISupports.h"
+
+#include <algorithm>  // std::min
+
+namespace mozilla::dom {
+
+using namespace streams_abstract;
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-queue-entry
+struct ReadableByteStreamQueueEntry
+    : LinkedListElement<RefPtr<ReadableByteStreamQueueEntry>> {
+  NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(
+      ReadableByteStreamQueueEntry)
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(
+      ReadableByteStreamQueueEntry)
+
+  ReadableByteStreamQueueEntry(JS::Handle<JSObject*> aBuffer,
+                               size_t aByteOffset, size_t aByteLength)
+      : mBuffer(aBuffer), mByteOffset(aByteOffset), mByteLength(aByteLength) {
+    mozilla::HoldJSObjects(this);
+  }
+
+  JSObject* Buffer() const { return mBuffer; }
+  void SetBuffer(JS::Handle<JSObject*> aBuffer) { mBuffer = aBuffer; }
+
+  size_t ByteOffset() const { return mByteOffset; }
+  void SetByteOffset(size_t aByteOffset) { mByteOffset = aByteOffset; }
+
+  size_t ByteLength() const { return mByteLength; }
+  void SetByteLength(size_t aByteLength) { mByteLength = aByteLength; }
+
+ private:
+  // An ArrayBuffer, which will be a transferred version of the one originally
+  // supplied by the underlying byte source.
+  JS::Heap<JSObject*> mBuffer;
+
+  // A nonnegative integer number giving the byte offset derived from the view
+  // originally supplied by the underlying byte source
+  size_t mByteOffset = 0;
+
+  // A nonnegative integer number giving the byte length derived from the view
+  // originally supplied by the underlying byte source
+  size_t mByteLength = 0;
+
+  ~ReadableByteStreamQueueEntry() { mozilla::DropJSObjects(this); }
+};
+
+NS_IMPL_CYCLE_COLLECTION_WITH_JS_MEMBERS(ReadableByteStreamQueueEntry, (),
+                                         (mBuffer));
+
+struct PullIntoDescriptor final
+    : LinkedListElement<RefPtr<PullIntoDescriptor>> {
+  NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(PullIntoDescriptor)
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(PullIntoDescriptor)
+
+  enum Constructor {
+    DataView,
+#define DEFINE_TYPED_CONSTRUCTOR_ENUM_NAMES(ExternalT, NativeT, Name) Name,
+    JS_FOR_EACH_TYPED_ARRAY(DEFINE_TYPED_CONSTRUCTOR_ENUM_NAMES)
+#undef DEFINE_TYPED_CONSTRUCTOR_ENUM_NAMES
+  };
+
+  static Constructor constructorFromScalar(JS::Scalar::Type type) {
+    switch (type) {
+#define REMAP_PULL_INTO_DESCRIPTOR_TYPE(ExternalT, NativeT, Name) \
+  case JS::Scalar::Name:                                          \
+    return Constructor::Name;
+      JS_FOR_EACH_TYPED_ARRAY(REMAP_PULL_INTO_DESCRIPTOR_TYPE)
+#undef REMAP
+
+      case JS::Scalar::Int64:
+      case JS::Scalar::Simd128:
+      case JS::Scalar::MaxTypedArrayViewType:
+        break;
+    }
+    MOZ_CRASH("Unexpected Scalar::Type");
+  }
+
+  PullIntoDescriptor(JS::Handle<JSObject*> aBuffer, uint64_t aBufferByteLength,
+                     uint64_t aByteOffset, uint64_t aByteLength,
+                     uint64_t aBytesFilled, uint64_t aElementSize,
+                     Constructor aViewConstructor, ReaderType aReaderType)
+      : mBuffer(aBuffer),
+        mBufferByteLength(aBufferByteLength),
+        mByteOffset(aByteOffset),
+        mByteLength(aByteLength),
+        mBytesFilled(aBytesFilled),
+        mElementSize(aElementSize),
+        mViewConstructor(aViewConstructor),
+        mReaderType(aReaderType) {
+    mozilla::HoldJSObjects(this);
+  }
+
+  JSObject* Buffer() const { return mBuffer; }
+  void SetBuffer(JS::Handle<JSObject*> aBuffer) { mBuffer = aBuffer; }
+
+  uint64_t BufferByteLength() const { return mBufferByteLength; }
+  void SetBufferByteLength(const uint64_t aBufferByteLength) {
+    mBufferByteLength = aBufferByteLength;
+  }
+
+  uint64_t ByteOffset() const { return mByteOffset; }
+  void SetByteOffset(const uint64_t aByteOffset) { mByteOffset = aByteOffset; }
+
+  uint64_t ByteLength() const { return mByteLength; }
+  void SetByteLength(const uint64_t aByteLength) { mByteLength = aByteLength; }
+
+  uint64_t BytesFilled() const { return mBytesFilled; }
+  void SetBytesFilled(const uint64_t aBytesFilled) {
+    mBytesFilled = aBytesFilled;
+  }
+
+  uint64_t ElementSize() const { return mElementSize; }
+  void SetElementSize(const uint64_t aElementSize) {
+    mElementSize = aElementSize;
+  }
+
+  Constructor ViewConstructor() const { return mViewConstructor; }
+
+  // Note: Named GetReaderType to avoid name conflict with type.
+  ReaderType GetReaderType() const { return mReaderType; }
+  void SetReaderType(const ReaderType aReaderType) {
+    mReaderType = aReaderType;
+  }
+
+ private:
+  JS::Heap<JSObject*> mBuffer;
+  uint64_t mBufferByteLength = 0;
+  uint64_t mByteOffset = 0;
+  uint64_t mByteLength = 0;
+  uint64_t mBytesFilled = 0;
+  uint64_t mElementSize = 0;
+  Constructor mViewConstructor;
+  ReaderType mReaderType;
+
+  ~PullIntoDescriptor() { mozilla::DropJSObjects(this); }
+};
+
+NS_IMPL_CYCLE_COLLECTION_WITH_JS_MEMBERS(PullIntoDescriptor, (), (mBuffer));
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(ReadableByteStreamController)
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(ReadableByteStreamController,
+                                                ReadableStreamController)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mByobRequest, mQueue, mPendingPullIntos)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(ReadableByteStreamController,
+                                                  ReadableStreamController)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mByobRequest, mQueue, mPendingPullIntos)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(ReadableByteStreamController,
+                                               ReadableStreamController)
+  NS_IMPL_CYCLE_COLLECTION_TRACE_PRESERVED_WRAPPER
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+NS_IMPL_ADDREF_INHERITED(ReadableByteStreamController, ReadableStreamController)
+NS_IMPL_RELEASE_INHERITED(ReadableByteStreamController,
+                          ReadableStreamController)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ReadableByteStreamController)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+NS_INTERFACE_MAP_END_INHERITING(ReadableStreamController)
+
+ReadableByteStreamController::ReadableByteStreamController(
+    nsIGlobalObject* aGlobal)
+    : ReadableStreamController(aGlobal) {}
+
+ReadableByteStreamController::~ReadableByteStreamController() = default;
+
+void ReadableByteStreamController::ClearQueue() { mQueue.clear(); }
+
+void ReadableByteStreamController::ClearPendingPullIntos() {
+  mPendingPullIntos.clear();
+}
+
+namespace streams_abstract {
+// https://streams.spec.whatwg.org/#abstract-opdef-readablebytestreamcontrollergetbyobrequest
+already_AddRefed<ReadableStreamBYOBRequest>
+ReadableByteStreamControllerGetBYOBRequest(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    ErrorResult& aRv) {
+  // Step 1.
+  if (!aController->GetByobRequest() &&
+      !aController->PendingPullIntos().isEmpty()) {
+    // Step 1.1:
+    PullIntoDescriptor* firstDescriptor =
+        aController->PendingPullIntos().getFirst();
+
+    // Step 1.2:
+    aRv.MightThrowJSException();
+    JS::Rooted<JSObject*> buffer(aCx, firstDescriptor->Buffer());
+    JS::Rooted<JSObject*> view(
+        aCx, JS_NewUint8ArrayWithBuffer(
+                 aCx, buffer,
+                 firstDescriptor->ByteOffset() + firstDescriptor->BytesFilled(),
+                 int64_t(firstDescriptor->ByteLength() -
+                         firstDescriptor->BytesFilled())));
+    if (!view) {
+      aRv.StealExceptionFromJSContext(aCx);
+      return nullptr;
+    }
+
+    // Step 1.3:
+    RefPtr<ReadableStreamBYOBRequest> byobRequest =
+        new ReadableStreamBYOBRequest(aController->GetParentObject());
+
+    // Step 1.4:
+    byobRequest->SetController(aController);
+
+    // Step 1.5:
+    byobRequest->SetView(view);
+
+    // Step 1.6:
+    aController->SetByobRequest(byobRequest);
+  }
+
+  // Step 2.
+  RefPtr<ReadableStreamBYOBRequest> request(aController->GetByobRequest());
+  return request.forget();
+}
+}  // namespace streams_abstract
+
+already_AddRefed<ReadableStreamBYOBRequest>
+ReadableByteStreamController::GetByobRequest(JSContext* aCx, ErrorResult& aRv) {
+  return ReadableByteStreamControllerGetBYOBRequest(aCx, this, aRv);
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-get-desired-size
+Nullable<double> ReadableByteStreamControllerGetDesiredSize(
+    const ReadableByteStreamController* aController) {
+  // Step 1.
+  ReadableStream::ReaderState state = aController->Stream()->State();
+
+  // Step 2.
+  if (state == ReadableStream::ReaderState::Errored) {
+    return nullptr;
+  }
+
+  // Step 3.
+  if (state == ReadableStream::ReaderState::Closed) {
+    return 0.0;
+  }
+
+  // Step 4.
+  return aController->StrategyHWM() - aController->QueueTotalSize();
+}
+
+Nullable<double> ReadableByteStreamController::GetDesiredSize() const {
+  // Step 1.
+  return ReadableByteStreamControllerGetDesiredSize(this);
+}
+
+JSObject* ReadableByteStreamController::WrapObject(
+    JSContext* aCx, JS::Handle<JSObject*> aGivenProto) {
+  return ReadableByteStreamController_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+namespace streams_abstract {
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-invalidate-byob-request
+static void ReadableByteStreamControllerInvalidateBYOBRequest(
+    ReadableByteStreamController* aController) {
+  // Step 1.
+  if (!aController->GetByobRequest()) {
+    return;
+  }
+
+  // Step 2.
+  aController->GetByobRequest()->SetController(nullptr);
+
+  // Step 3.
+  aController->GetByobRequest()->SetView(nullptr);
+
+  // Step 4.
+  aController->SetByobRequest(nullptr);
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-clear-pending-pull-intos
+void ReadableByteStreamControllerClearPendingPullIntos(
+    ReadableByteStreamController* aController) {
+  // Step 1.
+  ReadableByteStreamControllerInvalidateBYOBRequest(aController);
+
+  // Step 2.
+  aController->ClearPendingPullIntos();
+}
+
+// https://streams.spec.whatwg.org/#reset-queue
+void ResetQueue(ReadableByteStreamController* aContainer) {
+  // Step 1. Implied by type.
+  // Step 2.
+  aContainer->ClearQueue();
+
+  // Step 3.
+  aContainer->SetQueueTotalSize(0);
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-clear-algorithms
+void ReadableByteStreamControllerClearAlgorithms(
+    ReadableByteStreamController* aController) {
+  // Step 1. Set controller.[[pullAlgorithm]] to undefined.
+  // Step 2. Set controller.[[cancelAlgorithm]] to undefined.
+  aController->ClearAlgorithms();
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-error
+void ReadableByteStreamControllerError(
+    ReadableByteStreamController* aController, JS::Handle<JS::Value> aValue,
+    ErrorResult& aRv) {
+  // Step 1. Let stream be controller.[[stream]].
+  ReadableStream* stream = aController->Stream();
+
+  // Step 2. If stream.[[state]] is not "readable", return.
+  if (stream->State() != ReadableStream::ReaderState::Readable) {
+    return;
+  }
+
+  // Step 3. Perform
+  // !ReadableByteStreamControllerClearPendingPullIntos(controller).
+  ReadableByteStreamControllerClearPendingPullIntos(aController);
+
+  // Step 4. Perform !ResetQueue(controller).
+  ResetQueue(aController);
+
+  // Step 5. Perform !ReadableByteStreamControllerClearAlgorithms(controller).
+  ReadableByteStreamControllerClearAlgorithms(aController);
+
+  // Step 6. Perform !ReadableStreamError(stream, e).
+  AutoJSAPI jsapi;
+  if (!jsapi.Init(aController->GetParentObject())) {
+    return;
+  }
+  ReadableStreamError(jsapi.cx(), stream, aValue, aRv);
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-close
+void ReadableByteStreamControllerClose(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    ErrorResult& aRv) {
+  // Step 1.
+  RefPtr<ReadableStream> stream = aController->Stream();
+
+  // Step 2.
+  if (aController->CloseRequested() ||
+      stream->State() != ReadableStream::ReaderState::Readable) {
+    return;
+  }
+
+  // Step 3.
+  if (aController->QueueTotalSize() > 0) {
+    // Step 3.1
+    aController->SetCloseRequested(true);
+    // Step 3.2
+    return;
+  }
+
+  // Step 4.
+  if (!aController->PendingPullIntos().isEmpty()) {
+    // Step 4.1
+    PullIntoDescriptor* firstPendingPullInto =
+        aController->PendingPullIntos().getFirst();
+    // Step 4.2
+    if (firstPendingPullInto->BytesFilled() > 0) {
+      // Step 4.2.1
+      ErrorResult rv;
+      rv.ThrowTypeError("Leftover Bytes");
+
+      JS::Rooted<JS::Value> exception(aCx);
+      MOZ_ALWAYS_TRUE(ToJSValue(aCx, std::move(rv), &exception));
+
+      // Step 4.2.2
+      ReadableByteStreamControllerError(aController, exception, aRv);
+      if (aRv.Failed()) {
+        return;
+      }
+
+      aRv.MightThrowJSException();
+      aRv.ThrowJSException(aCx, exception);
+      return;
+    }
+  }
+
+  // Step 5.
+  ReadableByteStreamControllerClearAlgorithms(aController);
+
+  // Step 6.
+  ReadableStreamClose(aCx, stream, aRv);
+}
+
+}  // namespace streams_abstract
+
+// https://streams.spec.whatwg.org/#rbs-controller-close
+void ReadableByteStreamController::Close(JSContext* aCx, ErrorResult& aRv) {
+  // Step 1.
+  if (mCloseRequested) {
+    aRv.ThrowTypeError("Close already requested");
+    return;
+  }
+
+  // Step 2.
+  if (Stream()->State() != ReadableStream::ReaderState::Readable) {
+    aRv.ThrowTypeError("Closing un-readable stream controller");
+    return;
+  }
+
+  // Step 3.
+  ReadableByteStreamControllerClose(aCx, this, aRv);
+}
+
+namespace streams_abstract {
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-enqueue-chunk-to-queue
+void ReadableByteStreamControllerEnqueueChunkToQueue(
+    ReadableByteStreamController* aController,
+    JS::Handle<JSObject*> aTransferredBuffer, size_t aByteOffset,
+    size_t aByteLength) {
+  // Step 1.
+  RefPtr<ReadableByteStreamQueueEntry> queueEntry =
+      new ReadableByteStreamQueueEntry(aTransferredBuffer, aByteOffset,
+                                       aByteLength);
+  aController->Queue().insertBack(queueEntry);
+
+  // Step 2.
+  aController->AddToQueueTotalSize(double(aByteLength));
+}
+
+// https://streams.spec.whatwg.org/#abstract-opdef-readablebytestreamcontrollerenqueueclonedchunktoqueue
+void ReadableByteStreamControllerEnqueueClonedChunkToQueue(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    JS::Handle<JSObject*> aBuffer, size_t aByteOffset, size_t aByteLength,
+    ErrorResult& aRv) {
+  // Step 1. Let cloneResult be CloneArrayBuffer(buffer, byteOffset, byteLength,
+  // %ArrayBuffer%).
+  aRv.MightThrowJSException();
+  JS::Rooted<JSObject*> cloneResult(
+      aCx, JS::ArrayBufferClone(aCx, aBuffer, aByteOffset, aByteLength));
+
+  // Step 2. If cloneResult is an abrupt completion,
+  if (!cloneResult) {
+    JS::Rooted<JS::Value> exception(aCx);
+    if (!JS_GetPendingException(aCx, &exception)) {
+      // Uncatchable exception; we should mark aRv and return.
+      aRv.StealExceptionFromJSContext(aCx);
+      return;
+    }
+    JS_ClearPendingException(aCx);
+
+    // Step 2.1. Perform ! ReadableByteStreamControllerError(controller,
+    // cloneResult.[[Value]]).
+    ReadableByteStreamControllerError(aController, exception, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+
+    // Step 2.2. Return cloneResult.
+    aRv.ThrowJSException(aCx, exception);
+    return;
+  }
+
+  // Step 3. Perform !
+  // ReadableByteStreamControllerEnqueueChunkToQueue(controller,
+  // cloneResult.[[Value]], 0, byteLength).
+  ReadableByteStreamControllerEnqueueChunkToQueue(aController, cloneResult, 0,
+                                                  aByteLength);
+}
+
+already_AddRefed<PullIntoDescriptor>
+ReadableByteStreamControllerShiftPendingPullInto(
+    ReadableByteStreamController* aController);
+
+// https://streams.spec.whatwg.org/#abstract-opdef-readablebytestreamcontrollerenqueuedetachedpullintotoqueue
+void ReadableByteStreamControllerEnqueueDetachedPullIntoToQueue(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    PullIntoDescriptor* aPullIntoDescriptor, ErrorResult& aRv) {
+  // Step 1. Assert: pullIntoDescriptor’s reader type is "none".
+  MOZ_ASSERT(aPullIntoDescriptor->GetReaderType() == ReaderType::None);
+
+  // Step 2. If pullIntoDescriptor’s bytes filled > 0,
+  // perform ? ReadableByteStreamControllerEnqueueClonedChunkToQueue(controller,
+  // pullIntoDescriptor’s buffer, pullIntoDescriptor’s byte offset,
+  // pullIntoDescriptor’s bytes filled).
+  if (aPullIntoDescriptor->BytesFilled() > 0) {
+    JS::Rooted<JSObject*> buffer(aCx, aPullIntoDescriptor->Buffer());
+    ReadableByteStreamControllerEnqueueClonedChunkToQueue(
+        aCx, aController, buffer, aPullIntoDescriptor->ByteOffset(),
+        aPullIntoDescriptor->BytesFilled(), aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+  }
+
+  // Step 3. Perform !
+  // ReadableByteStreamControllerShiftPendingPullInto(controller).
+  RefPtr<PullIntoDescriptor> discarded =
+      ReadableByteStreamControllerShiftPendingPullInto(aController);
+  (void)discarded;
+}
+
+// https://streams.spec.whatwg.org/#readable-stream-get-num-read-into-requests
+static size_t ReadableStreamGetNumReadIntoRequests(ReadableStream* aStream) {
+  // Step 1.
+  MOZ_ASSERT(ReadableStreamHasBYOBReader(aStream));
+
+  // Step 2.
+  return aStream->GetReader()->AsBYOB()->ReadIntoRequests().length();
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-should-call-pull
+bool ReadableByteStreamControllerShouldCallPull(
+    ReadableByteStreamController* aController) {
+  // Step 1. Let stream be controller.[[stream]].
+  ReadableStream* stream = aController->Stream();
+
+  // Step 2. If stream.[[state]] is not "readable", return false.
+  if (stream->State() != ReadableStream::ReaderState::Readable) {
+    return false;
+  }
+
+  // Step 3. If controller.[[closeRequested]] is true, return false.
+  if (aController->CloseRequested()) {
+    return false;
+  }
+
+  // Step 4. If controller.[[started]] is false, return false.
+  if (!aController->Started()) {
+    return false;
+  }
+
+  // Step 5. If ! ReadableStreamHasDefaultReader(stream) is true
+  // and ! ReadableStreamGetNumReadRequests(stream) > 0, return true.
+  if (ReadableStreamHasDefaultReader(stream) &&
+      ReadableStreamGetNumReadRequests(stream) > 0) {
+    return true;
+  }
+
+  // Step 6. If ! ReadableStreamHasBYOBReader(stream) is true
+  // and ! ReadableStreamGetNumReadIntoRequests(stream) > 0, return true.
+  if (ReadableStreamHasBYOBReader(stream) &&
+      ReadableStreamGetNumReadIntoRequests(stream) > 0) {
+    return true;
+  }
+
+  // Step 7. Let desiredSize be
+  // ! ReadableByteStreamControllerGetDesiredSize(controller).
+  Nullable<double> desiredSize =
+      ReadableByteStreamControllerGetDesiredSize(aController);
+
+  // Step 8. Assert: desiredSize is not null.
+  MOZ_ASSERT(!desiredSize.IsNull());
+
+  // Step 9. If desiredSize > 0, return true.
+  // Step 10. Return false.
+  return desiredSize.Value() > 0;
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-call-pull-if-needed
+void ReadableByteStreamControllerCallPullIfNeeded(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    ErrorResult& aRv) {
+  // Step 1.
+  bool shouldPull = ReadableByteStreamControllerShouldCallPull(aController);
+
+  // Step 2.
+  if (!shouldPull) {
+    return;
+  }
+
+  // Step 3.
+  if (aController->Pulling()) {
+    aController->SetPullAgain(true);
+    return;
+  }
+
+  // Step 4.
+  MOZ_ASSERT(!aController->PullAgain());
+
+  // Step 5.
+  aController->SetPulling(true);
+
+  // Step 6.
+  RefPtr<ReadableStreamController> controller(aController);
+  RefPtr<UnderlyingSourceAlgorithmsBase> algorithms =
+      aController->GetAlgorithms();
+  RefPtr<Promise> pullPromise = algorithms->PullCallback(aCx, *controller, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Steps 7+8
+  pullPromise->AddCallbacksWithCycleCollectedArgs(
+      [](JSContext* aCx, JS::Handle<JS::Value> aValue, ErrorResult& aRv,
+         ReadableByteStreamController* aController)
+          MOZ_CAN_RUN_SCRIPT_BOUNDARY {
+            // Step 7.1
+            aController->SetPulling(false);
+            // Step 7.2
+            if (aController->PullAgain()) {
+              // Step 7.2.1
+              aController->SetPullAgain(false);
+
+              // Step 7.2.2
+              ReadableByteStreamControllerCallPullIfNeeded(
+                  aCx, MOZ_KnownLive(aController), aRv);
+            }
+          },
+      [](JSContext* aCx, JS::Handle<JS::Value> aValue, ErrorResult& aRv,
+         ReadableByteStreamController* aController) {
+        // Step 8.1
+        ReadableByteStreamControllerError(aController, aValue, aRv);
+      },
+      RefPtr(aController));
+}
+
+bool ReadableByteStreamControllerFillPullIntoDescriptorFromQueue(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    PullIntoDescriptor* aPullIntoDescriptor, ErrorResult& aRv);
+
+JSObject* ReadableByteStreamControllerConvertPullIntoDescriptor(
+    JSContext* aCx, PullIntoDescriptor* pullIntoDescriptor, ErrorResult& aRv);
+
+// https://streams.spec.whatwg.org/#readable-stream-fulfill-read-into-request
+MOZ_CAN_RUN_SCRIPT
+void ReadableStreamFulfillReadIntoRequest(JSContext* aCx,
+                                          ReadableStream* aStream,
+                                          JS::Handle<JS::Value> aChunk,
+                                          bool done, ErrorResult& aRv) {
+  // Step 1. Assert: !ReadableStreamHasBYOBReader(stream) is true.
+  MOZ_ASSERT(ReadableStreamHasBYOBReader(aStream));
+
+  // Step 2. Let reader be stream.[[reader]].
+  ReadableStreamBYOBReader* reader = aStream->GetReader()->AsBYOB();
+
+  // Step 3. Assert: reader.[[readIntoRequests]] is not empty.
+  MOZ_ASSERT(!reader->ReadIntoRequests().isEmpty());
+
+  // Step 4. Let readIntoRequest be reader.[[readIntoRequests]][0].
+  // Step 5. Remove readIntoRequest from reader.[[readIntoRequests]].
+  RefPtr<ReadIntoRequest> readIntoRequest =
+      reader->ReadIntoRequests().popFirst();
+
+  // Step 6. If done is true, perform readIntoRequest’s close steps, given
+  // chunk.
+  if (done) {
+    readIntoRequest->CloseSteps(aCx, aChunk, aRv);
+    return;
+  }
+
+  // Step 7. Otherwise, perform readIntoRequest’s chunk steps, given chunk.
+  readIntoRequest->ChunkSteps(aCx, aChunk, aRv);
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-commit-pull-into-descriptor
+MOZ_CAN_RUN_SCRIPT
+void ReadableByteStreamControllerCommitPullIntoDescriptor(
+    JSContext* aCx, ReadableStream* aStream,
+    PullIntoDescriptor* pullIntoDescriptor, ErrorResult& aRv) {
+  // Step 1. Assert: stream.[[state]] is not "errored".
+  MOZ_ASSERT(aStream->State() != ReadableStream::ReaderState::Errored);
+
+  // Step 2. Assert: pullIntoDescriptor.reader type is not "none".
+  MOZ_ASSERT(pullIntoDescriptor->GetReaderType() != ReaderType::None);
+
+  // Step 3. Let done be false.
+  bool done = false;
+
+  // Step 4. If stream.[[state]] is "closed",
+  if (aStream->State() == ReadableStream::ReaderState::Closed) {
+    // Step 4.1. Assert: pullIntoDescriptor’s bytes filled is 0.
+    MOZ_ASSERT(pullIntoDescriptor->BytesFilled() == 0);
+
+    // Step 4.2. Set done to true.
+    done = true;
+  }
+
+  // Step 5. Let filledView be !
+  // ReadableByteStreamControllerConvertPullIntoDescriptor(pullIntoDescriptor).
+  JS::Rooted<JSObject*> filledView(
+      aCx, ReadableByteStreamControllerConvertPullIntoDescriptor(
+               aCx, pullIntoDescriptor, aRv));
+  if (aRv.Failed()) {
+    return;
+  }
+  JS::Rooted<JS::Value> filledViewValue(aCx, JS::ObjectValue(*filledView));
+
+  // Step 6. If pullIntoDescriptor’s reader type is "default",
+  if (pullIntoDescriptor->GetReaderType() == ReaderType::Default) {
+    // Step 6.1. Perform !ReadableStreamFulfillReadRequest(stream, filledView,
+    // done).
+    ReadableStreamFulfillReadRequest(aCx, aStream, filledViewValue, done, aRv);
+    return;
+  }
+
+  // Step 7.1. Assert: pullIntoDescriptor’s reader type is "byob".
+  MOZ_ASSERT(pullIntoDescriptor->GetReaderType() == ReaderType::BYOB);
+
+  // Step 7.2 Perform !ReadableStreamFulfillReadIntoRequest(stream, filledView,
+  // done).
+  ReadableStreamFulfillReadIntoRequest(aCx, aStream, filledViewValue, done,
+                                       aRv);
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-process-pull-into-descriptors-using-queue
+MOZ_CAN_RUN_SCRIPT
+void ReadableByteStreamControllerProcessPullIntoDescriptorsUsingQueue(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    ErrorResult& aRv) {
+  // Step 1. Assert: controller.[[closeRequested]] is false.
+  MOZ_ASSERT(!aController->CloseRequested());
+
+  // Step 2. While controller.[[pendingPullIntos]] is not empty,
+  while (!aController->PendingPullIntos().isEmpty()) {
+    // Step 2.1 If controller.[[queueTotalSize]] is 0, return.
+    if (aController->QueueTotalSize() == 0) {
+      return;
+    }
+
+    // Step 2.2. Let pullIntoDescriptor be controller.[[pendingPullIntos]][0].
+    RefPtr<PullIntoDescriptor> pullIntoDescriptor =
+        aController->PendingPullIntos().getFirst();
+
+    // Step 2.3. If
+    // !ReadableByteStreamControllerFillPullIntoDescriptorFromQueue(controller,
+    // pullIntoDescriptor) is true,
+    bool ready = ReadableByteStreamControllerFillPullIntoDescriptorFromQueue(
+        aCx, aController, pullIntoDescriptor, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+
+    if (ready) {
+      //  Step 2.3.1. Perform
+      //  !ReadableByteStreamControllerShiftPendingPullInto(controller).
+      RefPtr<PullIntoDescriptor> discardedPullIntoDescriptor =
+          ReadableByteStreamControllerShiftPendingPullInto(aController);
+
+      // Step 2.3.2. Perform
+      // !ReadableByteStreamControllerCommitPullIntoDescriptor(controller.[[stream]],
+      //         pullIntoDescriptor).
+      RefPtr<ReadableStream> stream(aController->Stream());
+      ReadableByteStreamControllerCommitPullIntoDescriptor(
+          aCx, stream, pullIntoDescriptor, aRv);
+      if (aRv.Failed()) {
+        return;
+      }
+    }
+  }
+}
+
+MOZ_CAN_RUN_SCRIPT
+void ReadableByteStreamControllerHandleQueueDrain(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    ErrorResult& aRv);
+
+// https://streams.spec.whatwg.org/#abstract-opdef-readablebytestreamcontrollerfillreadrequestfromqueue
+MOZ_CAN_RUN_SCRIPT void ReadableByteStreamControllerFillReadRequestFromQueue(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    ReadRequest* aReadRequest, ErrorResult& aRv) {
+  // Step 1. Assert: controller.[[queueTotalSize]] > 0.
+  MOZ_ASSERT(aController->QueueTotalSize() > 0);
+  // Also assert that the queue has a non-zero length;
+  MOZ_ASSERT(aController->Queue().length() > 0);
+
+  // Step 2. Let entry be controller.[[queue]][0].
+  // Step 3. Remove entry from controller.[[queue]].
+  RefPtr<ReadableByteStreamQueueEntry> entry = aController->Queue().popFirst();
+
+  // Assert that we actually got an entry.
+  MOZ_ASSERT(entry);
+
+  // Step 4. Set controller.[[queueTotalSize]] to controller.[[queueTotalSize]]
+  // − entry’s byte length.
+  aController->SetQueueTotalSize(aController->QueueTotalSize() -
+                                 double(entry->ByteLength()));
+
+  // Step 5. Perform ! ReadableByteStreamControllerHandleQueueDrain(controller).
+  ReadableByteStreamControllerHandleQueueDrain(aCx, aController, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Step 6. Let view be ! Construct(%Uint8Array%, « entry’s buffer, entry’s
+  // byte offset, entry’s byte length »).
+  aRv.MightThrowJSException();
+  JS::Rooted<JSObject*> buffer(aCx, entry->Buffer());
+  JS::Rooted<JSObject*> view(
+      aCx, JS_NewUint8ArrayWithBuffer(aCx, buffer, entry->ByteOffset(),
+                                      int64_t(entry->ByteLength())));
+  if (!view) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return;
+  }
+
+  // Step 7. Perform readRequest’s chunk steps, given view.
+  JS::Rooted<JS::Value> viewValue(aCx, JS::ObjectValue(*view));
+  aReadRequest->ChunkSteps(aCx, viewValue, aRv);
+}
+
+MOZ_CAN_RUN_SCRIPT void
+ReadableByteStreamControllerProcessReadRequestsUsingQueue(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    ErrorResult& aRv) {
+  // Step 1. Let reader be controller.[[stream]].[[reader]].
+  // Step 2. Assert: reader implements ReadableStreamDefaultReader.
+  RefPtr<ReadableStreamDefaultReader> reader =
+      aController->Stream()->GetDefaultReader();
+
+  // Step 3. While reader.[[readRequests]] is not empty,
+  while (!reader->ReadRequests().isEmpty()) {
+    // Step 3.1. If controller.[[queueTotalSize]] is 0, return.
+    if (aController->QueueTotalSize() == 0) {
+      return;
+    }
+
+    // Step 3.2. Let readRequest be reader.[[readRequests]][0].
+    // Step 3.3. Remove readRequest from reader.[[readRequests]].
+    RefPtr<ReadRequest> readRequest = reader->ReadRequests().popFirst();
+
+    // Step 3.4. Perform !
+    // ReadableByteStreamControllerFillReadRequestFromQueue(controller,
+    // readRequest).
+    ReadableByteStreamControllerFillReadRequestFromQueue(aCx, aController,
+                                                         readRequest, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+  }
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-enqueue
+void ReadableByteStreamControllerEnqueue(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    JS::Handle<JSObject*> aChunk, ErrorResult& aRv) {
+  aRv.MightThrowJSException();
+
+  // Step 1.
+  RefPtr<ReadableStream> stream = aController->Stream();
+
+  // Step 2.
+  if (aController->CloseRequested() ||
+      stream->State() != ReadableStream::ReaderState::Readable) {
+    return;
+  }
+
+  // Step 3.
+  bool isShared;
+  JS::Rooted<JSObject*> buffer(
+      aCx, JS_GetArrayBufferViewBuffer(aCx, aChunk, &isShared));
+  if (!buffer) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return;
+  }
+
+  // Step 4.
+  size_t byteOffset = JS_GetArrayBufferViewByteOffset(aChunk);
+
+  // Step 5.
+  size_t byteLength = JS_GetArrayBufferViewByteLength(aChunk);
+
+  // Step 6.
+  if (JS::IsDetachedArrayBufferObject(buffer)) {
+    aRv.ThrowTypeError("Detached Array Buffer");
+    return;
+  }
+
+  // Step 7.
+  JS::Rooted<JSObject*> transferredBuffer(aCx,
+                                          TransferArrayBuffer(aCx, buffer));
+  if (!transferredBuffer) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return;
+  }
+
+  // Step 8.
+  if (!aController->PendingPullIntos().isEmpty()) {
+    // Step 8.1
+    RefPtr<PullIntoDescriptor> firstPendingPullInto =
+        aController->PendingPullIntos().getFirst();
+
+    // Step 8.2
+    JS::Rooted<JSObject*> pendingBuffer(aCx, firstPendingPullInto->Buffer());
+    if (JS::IsDetachedArrayBufferObject(pendingBuffer)) {
+      aRv.ThrowTypeError("Pending PullInto has detached buffer");
+      return;
+    }
+
+    // Step 8.3. Perform !
+    // ReadableByteStreamControllerInvalidateBYOBRequest(controller).
+    ReadableByteStreamControllerInvalidateBYOBRequest(aController);
+
+    // Step 8.4. Set firstPendingPullInto’s buffer to !
+    // TransferArrayBuffer(firstPendingPullInto’s buffer).
+    pendingBuffer = TransferArrayBuffer(aCx, pendingBuffer);
+    if (!pendingBuffer) {
+      aRv.StealExceptionFromJSContext(aCx);
+      return;
+    }
+    firstPendingPullInto->SetBuffer(pendingBuffer);
+
+    // Step 8.5. If firstPendingPullInto’s reader type is "none", perform ?
+    // ReadableByteStreamControllerEnqueueDetachedPullIntoToQueue(controller,
+    // firstPendingPullInto).
+    if (firstPendingPullInto->GetReaderType() == ReaderType::None) {
+      ReadableByteStreamControllerEnqueueDetachedPullIntoToQueue(
+          aCx, aController, firstPendingPullInto, aRv);
+      if (aRv.Failed()) {
+        return;
+      }
+    }
+  }
+
+  // Step 9. If ! ReadableStreamHasDefaultReader(stream) is true,
+  if (ReadableStreamHasDefaultReader(stream)) {
+    // Step 9.1. Perform !
+    // ReadableByteStreamControllerProcessReadRequestsUsingQueue(controller).
+    ReadableByteStreamControllerProcessReadRequestsUsingQueue(aCx, aController,
+                                                              aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+
+    // Step 9.2. If ! ReadableStreamGetNumReadRequests(stream) is 0,
+    if (ReadableStreamGetNumReadRequests(stream) == 0) {
+      // Step 9.2.1 Assert: controller.[[pendingPullIntos]] is empty.
+      MOZ_ASSERT(aController->PendingPullIntos().isEmpty());
+
+      // Step 9.2.2. Perform !
+      // ReadableByteStreamControllerEnqueueChunkToQueue(controller,
+      // transferredBuffer, byteOffset, byteLength).
+      ReadableByteStreamControllerEnqueueChunkToQueue(
+          aController, transferredBuffer, byteOffset, byteLength);
+
+      // Step 9.3. Otherwise,
+    } else {
+      // Step 9.3.1 Assert: controller.[[queue]] is empty.
+      MOZ_ASSERT(aController->Queue().isEmpty());
+
+      // Step 9.3.2. If controller.[[pendingPullIntos]] is not empty,
+      if (!aController->PendingPullIntos().isEmpty()) {
+        // Step 9.3.2.1. Assert: controller.[[pendingPullIntos]][0]'s reader
+        // type is "default".
+        MOZ_ASSERT(
+            aController->PendingPullIntos().getFirst()->GetReaderType() ==
+            ReaderType::Default);
+
+        // Step 9.3.2.2. Perform !
+        // ReadableByteStreamControllerShiftPendingPullInto(controller).
+        RefPtr<PullIntoDescriptor> pullIntoDescriptor =
+            ReadableByteStreamControllerShiftPendingPullInto(aController);
+        (void)pullIntoDescriptor;
+      }
+
+      // Step 9.3.3. Let transferredView be ! Construct(%Uint8Array%, «
+      // transferredBuffer, byteOffset, byteLength »).
+      JS::Rooted<JSObject*> transferredView(
+          aCx, JS_NewUint8ArrayWithBuffer(aCx, transferredBuffer, byteOffset,
+                                          int64_t(byteLength)));
+      if (!transferredView) {
+        aRv.StealExceptionFromJSContext(aCx);
+        return;
+      }
+
+      // Step 9.3.4. Perform ! ReadableStreamFulfillReadRequest(stream,
+      // transferredView, false).
+      JS::Rooted<JS::Value> transferredViewValue(
+          aCx, JS::ObjectValue(*transferredView));
+      ReadableStreamFulfillReadRequest(aCx, stream, transferredViewValue, false,
+                                       aRv);
+      if (aRv.Failed()) {
+        return;
+      }
+    }
+
+    // Step 10. Otherwise, if ! ReadableStreamHasBYOBReader(stream) is true,
+  } else if (ReadableStreamHasBYOBReader(stream)) {
+    // Step 10.1. Perform !
+    // ReadableByteStreamControllerEnqueueChunkToQueue(controller,
+    // transferredBuffer, byteOffset, byteLength).
+    ReadableByteStreamControllerEnqueueChunkToQueue(
+        aController, transferredBuffer, byteOffset, byteLength);
+
+    // Step 10.2 Perform !
+    // ReadableByteStreamControllerProcessPullIntoDescriptorsUsingQueue(controller).
+    ReadableByteStreamControllerProcessPullIntoDescriptorsUsingQueue(
+        aCx, aController, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+
+    // Step 11. Otherwise,
+  } else {
+    // Step 11.1. Assert: ! IsReadableStreamLocked(stream) is false.
+    MOZ_ASSERT(!IsReadableStreamLocked(stream));
+
+    // Step 11.2. Perform !
+    // ReadableByteStreamControllerEnqueueChunkToQueue(controller,
+    // transferredBuffer, byteOffset, byteLength).
+    ReadableByteStreamControllerEnqueueChunkToQueue(
+        aController, transferredBuffer, byteOffset, byteLength);
+  }
+
+  // Step 12. Perform !
+  // ReadableByteStreamControllerCallPullIfNeeded(controller).
+  ReadableByteStreamControllerCallPullIfNeeded(aCx, aController, aRv);
+}
+
+}  // namespace streams_abstract
+
+// https://streams.spec.whatwg.org/#rbs-controller-enqueue
+void ReadableByteStreamController::Enqueue(JSContext* aCx,
+                                           const ArrayBufferView& aChunk,
+                                           ErrorResult& aRv) {
+  // Step 1.
+  JS::Rooted<JSObject*> chunk(aCx, aChunk.Obj());
+  if (JS_GetArrayBufferViewByteLength(chunk) == 0) {
+    aRv.ThrowTypeError("Zero Length View");
+    return;
+  }
+
+  // Step 2.
+  bool isShared;
+  JS::Rooted<JSObject*> viewedArrayBuffer(
+      aCx, JS_GetArrayBufferViewBuffer(aCx, chunk, &isShared));
+  if (!viewedArrayBuffer) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return;
+  }
+
+  if (JS::GetArrayBufferByteLength(viewedArrayBuffer) == 0) {
+    aRv.ThrowTypeError("Zero Length Buffer");
+    return;
+  }
+
+  // Step 3.
+  if (CloseRequested()) {
+    aRv.ThrowTypeError("close requested");
+    return;
+  }
+
+  // Step 4.
+  if (Stream()->State() != ReadableStream::ReaderState::Readable) {
+    aRv.ThrowTypeError("Not Readable");
+    return;
+  }
+
+  // Step 5.
+  ReadableByteStreamControllerEnqueue(aCx, this, chunk, aRv);
+}
+
+// https://streams.spec.whatwg.org/#rbs-controller-error
+void ReadableByteStreamController::Error(JSContext* aCx,
+                                         JS::Handle<JS::Value> aErrorValue,
+                                         ErrorResult& aRv) {
+  // Step 1.
+  ReadableByteStreamControllerError(this, aErrorValue, aRv);
+}
+
+// https://streams.spec.whatwg.org/#rbs-controller-private-cancel
+already_AddRefed<Promise> ReadableByteStreamController::CancelSteps(
+    JSContext* aCx, JS::Handle<JS::Value> aReason, ErrorResult& aRv) {
+  // Step 1.
+  ReadableByteStreamControllerClearPendingPullIntos(this);
+
+  // Step 2.
+  ResetQueue(this);
+
+  // Step 3.
+  Optional<JS::Handle<JS::Value>> reason(aCx, aReason);
+  RefPtr<UnderlyingSourceAlgorithmsBase> algorithms = mAlgorithms;
+  RefPtr<Promise> result = algorithms->CancelCallback(aCx, reason, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+  // Step 4.
+  ReadableByteStreamControllerClearAlgorithms(this);
+
+  // Step 5.
+  return result.forget();
+}
+
+namespace streams_abstract {
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-handle-queue-drain
+void ReadableByteStreamControllerHandleQueueDrain(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    ErrorResult& aRv) {
+  // Step 1.
+  MOZ_ASSERT(aController->Stream()->State() ==
+             ReadableStream::ReaderState::Readable);
+
+  // Step 2.
+  if (aController->QueueTotalSize() == 0 && aController->CloseRequested()) {
+    // Step 2.1
+    ReadableByteStreamControllerClearAlgorithms(aController);
+
+    // Step 2.2
+    RefPtr<ReadableStream> stream = aController->Stream();
+    ReadableStreamClose(aCx, stream, aRv);
+    return;
+  }
+
+  // Step 3.1
+  ReadableByteStreamControllerCallPullIfNeeded(aCx, aController, aRv);
+}
+}  // namespace streams_abstract
+
+// https://streams.spec.whatwg.org/#rbs-controller-private-pull
+void ReadableByteStreamController::PullSteps(JSContext* aCx,
+                                             ReadRequest* aReadRequest,
+                                             ErrorResult& aRv) {
+  // Step 1.
+  ReadableStream* stream = Stream();
+
+  // Step 2.
+  MOZ_ASSERT(ReadableStreamHasDefaultReader(stream));
+
+  // Step 3.
+  if (QueueTotalSize() > 0) {
+    // Step 3.1. Assert: ! ReadableStreamGetNumReadRequests ( stream ) is 0.
+    MOZ_ASSERT(ReadableStreamGetNumReadRequests(stream) == 0);
+
+    // Step 3.2. Perform !
+    // ReadableByteStreamControllerFillReadRequestFromQueue(this, readRequest).
+    ReadableByteStreamControllerFillReadRequestFromQueue(aCx, this,
+                                                         aReadRequest, aRv);
+
+    // Step 3.3. Return.
+    return;
+  }
+
+  // Step 4.
+  Maybe<uint64_t> autoAllocateChunkSize = AutoAllocateChunkSize();
+
+  // Step 5.
+  if (autoAllocateChunkSize) {
+    // Step 5.1
+    aRv.MightThrowJSException();
+    JS::Rooted<JSObject*> buffer(
+        aCx, JS::NewArrayBuffer(aCx, *autoAllocateChunkSize));
+    // Step 5.2
+    if (!buffer) {
+      // Step 5.2.1
+      JS::Rooted<JS::Value> bufferError(aCx);
+      if (!JS_GetPendingException(aCx, &bufferError)) {
+        // Uncatchable exception; we should mark aRv and return.
+        aRv.StealExceptionFromJSContext(aCx);
+        return;
+      }
+
+      // It's not expliclitly stated, but I assume the intention here is that
+      // we perform a normal completion here.
+      JS_ClearPendingException(aCx);
+
+      aReadRequest->ErrorSteps(aCx, bufferError, aRv);
+
+      // Step 5.2.2.
+      return;
+    }
+
+    // Step 5.3
+    RefPtr<PullIntoDescriptor> pullIntoDescriptor = new PullIntoDescriptor(
+        buffer, *autoAllocateChunkSize, 0, *autoAllocateChunkSize, 0, 1,
+        PullIntoDescriptor::Constructor::Uint8, ReaderType::Default);
+
+    //  Step 5.4
+    PendingPullIntos().insertBack(pullIntoDescriptor);
+  }
+
+  // Step 6.
+  ReadableStreamAddReadRequest(stream, aReadRequest);
+
+  // Step 7.
+  ReadableByteStreamControllerCallPullIfNeeded(aCx, this, aRv);
+}
+
+// https://streams.spec.whatwg.org/#abstract-opdef-readablebytestreamcontroller-releasesteps
+void ReadableByteStreamController::ReleaseSteps() {
+  // Step 1. If this.[[pendingPullIntos]] is not empty,
+  if (!PendingPullIntos().isEmpty()) {
+    // Step 1.1. Let firstPendingPullInto be this.[[pendingPullIntos]][0].
+    RefPtr<PullIntoDescriptor> firstPendingPullInto =
+        PendingPullIntos().popFirst();
+
+    // Step 1.2. Set firstPendingPullInto’s reader type to "none".
+    firstPendingPullInto->SetReaderType(ReaderType::None);
+
+    // Step 1.3. Set this.[[pendingPullIntos]] to the list «
+    // firstPendingPullInto ».
+    PendingPullIntos().clear();
+    PendingPullIntos().insertBack(firstPendingPullInto);
+  }
+}
+
+namespace streams_abstract {
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-shift-pending-pull-into
+already_AddRefed<PullIntoDescriptor>
+ReadableByteStreamControllerShiftPendingPullInto(
+    ReadableByteStreamController* aController) {
+  // Step 1.
+  MOZ_ASSERT(!aController->GetByobRequest());
+
+  // Step 2 + 3
+  RefPtr<PullIntoDescriptor> descriptor =
+      aController->PendingPullIntos().popFirst();
+
+  // Step 4.
+  return descriptor.forget();
+}
+
+JSObject* ConstructFromPullIntoConstructor(
+    JSContext* aCx, PullIntoDescriptor::Constructor constructor,
+    JS::Handle<JSObject*> buffer, size_t byteOffset, size_t length) {
+  switch (constructor) {
+    case PullIntoDescriptor::Constructor::DataView:
+      return JS_NewDataView(aCx, buffer, byteOffset, length);
+      break;
+
+#define CONSTRUCT_TYPED_ARRAY_TYPE(ExternalT, NativeT, Name)      \
+  case PullIntoDescriptor::Constructor::Name:                     \
+    return JS_New##Name##ArrayWithBuffer(aCx, buffer, byteOffset, \
+                                         int64_t(length));        \
+    break;
+
+      JS_FOR_EACH_TYPED_ARRAY(CONSTRUCT_TYPED_ARRAY_TYPE)
+
+#undef CONSTRUCT_TYPED_ARRAY_TYPE
+
+    default:
+      MOZ_ASSERT_UNREACHABLE("Unknown PullIntoDescriptor::Constructor");
+      return nullptr;
+  }
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-convert-pull-into-descriptor
+JSObject* ReadableByteStreamControllerConvertPullIntoDescriptor(
+    JSContext* aCx, PullIntoDescriptor* pullIntoDescriptor, ErrorResult& aRv) {
+  // Step 1. Let bytesFilled be pullIntoDescriptor’s bytes filled.
+  uint64_t bytesFilled = pullIntoDescriptor->BytesFilled();
+
+  // Step 2. Let elementSize be pullIntoDescriptor’s element size.
+  uint64_t elementSize = pullIntoDescriptor->ElementSize();
+
+  // Step 3. Assert: bytesFilled ≤ pullIntoDescriptor’s byte length.
+  MOZ_ASSERT(bytesFilled <= pullIntoDescriptor->ByteLength());
+
+  // Step 4. Assert: bytesFilled mod elementSize is 0.
+  MOZ_ASSERT(bytesFilled % elementSize == 0);
+
+  // Step 5. Let buffer be ! TransferArrayBuffer(pullIntoDescriptor’s buffer).
+  aRv.MightThrowJSException();
+  JS::Rooted<JSObject*> srcBuffer(aCx, pullIntoDescriptor->Buffer());
+  JS::Rooted<JSObject*> buffer(aCx, TransferArrayBuffer(aCx, srcBuffer));
+  if (!buffer) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return nullptr;
+  }
+
+  // Step 6. Return ! Construct(pullIntoDescriptor’s view constructor,
+  //  « buffer, pullIntoDescriptor’s byte offset, bytesFilled ÷ elementSize »).
+  JS::Rooted<JSObject*> res(
+      aCx, ConstructFromPullIntoConstructor(
+               aCx, pullIntoDescriptor->ViewConstructor(), buffer,
+               pullIntoDescriptor->ByteOffset(), bytesFilled / elementSize));
+  if (!res) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return nullptr;
+  }
+  return res;
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-respond-in-closed-state
+MOZ_CAN_RUN_SCRIPT
+static void ReadableByteStreamControllerRespondInClosedState(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    RefPtr<PullIntoDescriptor>& aFirstDescriptor, ErrorResult& aRv) {
+  // Step 1. Assert: firstDescriptor ’s bytes filled is 0.
+  MOZ_ASSERT(aFirstDescriptor->BytesFilled() == 0);
+
+  // Step 2. If firstDescriptor’s reader type is "none",
+  // perform ! ReadableByteStreamControllerShiftPendingPullInto(controller).
+  if (aFirstDescriptor->GetReaderType() == ReaderType::None) {
+    RefPtr<PullIntoDescriptor> discarded =
+        ReadableByteStreamControllerShiftPendingPullInto(aController);
+    (void)discarded;
+  }
+
+  // Step 3. Let stream be controller.[[stream]].
+  RefPtr<ReadableStream> stream = aController->Stream();
+
+  // Step 4. If ! ReadableStreamHasBYOBReader(stream) is true,
+  if (ReadableStreamHasBYOBReader(stream)) {
+    // Step 4.1. While ! ReadableStreamGetNumReadIntoRequests(stream) > 0,
+    while (ReadableStreamGetNumReadIntoRequests(stream) > 0) {
+      // Step 4.1.1. Let pullIntoDescriptor be !
+      // ReadableByteStreamControllerShiftPendingPullInto(controller).
+      RefPtr<PullIntoDescriptor> pullIntoDescriptor =
+          ReadableByteStreamControllerShiftPendingPullInto(aController);
+
+      // Step 4.1.2. Perform !
+      // ReadableByteStreamControllerCommitPullIntoDescriptor(stream,
+      // pullIntoDescriptor).
+      ReadableByteStreamControllerCommitPullIntoDescriptor(
+          aCx, stream, pullIntoDescriptor, aRv);
+    }
+  }
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-fill-head-pull-into-descriptor
+void ReadableByteStreamControllerFillHeadPullIntoDescriptor(
+    ReadableByteStreamController* aController, size_t aSize,
+    PullIntoDescriptor* aPullIntoDescriptor) {
+  // Step 1. Assert: either controller.[[pendingPullIntos]] is empty, or
+  // controller.[[pendingPullIntos]][0] is pullIntoDescriptor.
+  MOZ_ASSERT(aController->PendingPullIntos().isEmpty() ||
+             aController->PendingPullIntos().getFirst() == aPullIntoDescriptor);
+
+  // Step 2. Assert: controller.[[byobRequest]] is null.
+  MOZ_ASSERT(!aController->GetByobRequest());
+
+  // Step 3. Set pullIntoDescriptor’s bytes filled to bytes filled + size.
+  aPullIntoDescriptor->SetBytesFilled(aPullIntoDescriptor->BytesFilled() +
+                                      aSize);
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-respond-in-readable-state
+MOZ_CAN_RUN_SCRIPT
+static void ReadableByteStreamControllerRespondInReadableState(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    uint64_t aBytesWritten, PullIntoDescriptor* aPullIntoDescriptor,
+    ErrorResult& aRv) {
+  // Step 1. Assert: pullIntoDescriptor’s bytes filled + bytesWritten ≤
+  // pullIntoDescriptor’s byte length.
+  MOZ_ASSERT(aPullIntoDescriptor->BytesFilled() + aBytesWritten <=
+             aPullIntoDescriptor->ByteLength());
+
+  // Step 2. Perform
+  // !ReadableByteStreamControllerFillHeadPullIntoDescriptor(controller,
+  // bytesWritten, pullIntoDescriptor).
+  ReadableByteStreamControllerFillHeadPullIntoDescriptor(
+      aController, aBytesWritten, aPullIntoDescriptor);
+
+  // Step 3. If pullIntoDescriptor’s reader type is "none",
+  if (aPullIntoDescriptor->GetReaderType() == ReaderType::None) {
+    // Step 3.1. Perform ?
+    // ReadableByteStreamControllerEnqueueDetachedPullIntoToQueue(controller,
+    // pullIntoDescriptor).
+    ReadableByteStreamControllerEnqueueDetachedPullIntoToQueue(
+        aCx, aController, aPullIntoDescriptor, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+
+    // Step 3.2. Perform !
+    // ReadableByteStreamControllerProcessPullIntoDescriptorsUsingQueue(controller).
+    ReadableByteStreamControllerProcessPullIntoDescriptorsUsingQueue(
+        aCx, aController, aRv);
+
+    // Step 3.3. Return.
+    return;
+  }
+
+  // Step 4. If pullIntoDescriptor’s bytes filled < pullIntoDescriptor’s element
+  // size, return.
+  if (aPullIntoDescriptor->BytesFilled() < aPullIntoDescriptor->ElementSize()) {
+    return;
+  }
+
+  // Step 5. Perform
+  // !ReadableByteStreamControllerShiftPendingPullInto(controller).
+  RefPtr<PullIntoDescriptor> pullIntoDescriptor =
+      ReadableByteStreamControllerShiftPendingPullInto(aController);
+  (void)pullIntoDescriptor;
+
+  // Step 6. Let remainderSize be pullIntoDescriptor’s bytes filled mod
+  // pullIntoDescriptor’s element size.
+  size_t remainderSize =
+      aPullIntoDescriptor->BytesFilled() % aPullIntoDescriptor->ElementSize();
+
+  // Step 7. If remainderSize > 0,
+  if (remainderSize > 0) {
+    // Step 7.1. Let end be pullIntoDescriptor’s byte offset +
+    // pullIntoDescriptor’s bytes filled.
+    size_t end =
+        aPullIntoDescriptor->ByteOffset() + aPullIntoDescriptor->BytesFilled();
+
+    // Step 7.2. Perform ?
+    // ReadableByteStreamControllerEnqueueClonedChunkToQueue(controller,
+    // pullIntoDescriptor’s buffer, end − remainderSize, remainderSize).
+    JS::Rooted<JSObject*> pullIntoBuffer(aCx, aPullIntoDescriptor->Buffer());
+    ReadableByteStreamControllerEnqueueClonedChunkToQueue(
+        aCx, aController, pullIntoBuffer, end - remainderSize, remainderSize,
+        aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+  }
+
+  // Step 8. Set pullIntoDescriptor’s bytes filled to pullIntoDescriptor’s bytes
+  // filled − remainderSize.
+  aPullIntoDescriptor->SetBytesFilled(aPullIntoDescriptor->BytesFilled() -
+                                      remainderSize);
+
+  // Step 9. Perform
+  // !ReadableByteStreamControllerCommitPullIntoDescriptor(controller.[[stream]],
+  // pullIntoDescriptor).
+  RefPtr<ReadableStream> stream(aController->Stream());
+  ReadableByteStreamControllerCommitPullIntoDescriptor(
+      aCx, stream, aPullIntoDescriptor, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Step 10. Perform
+  // !ReadableByteStreamControllerProcessPullIntoDescriptorsUsingQueue(controller).
+  ReadableByteStreamControllerProcessPullIntoDescriptorsUsingQueue(
+      aCx, aController, aRv);
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-respond-internal
+void ReadableByteStreamControllerRespondInternal(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    uint64_t aBytesWritten, ErrorResult& aRv) {
+  // Step 1.
+  RefPtr<PullIntoDescriptor> firstDescriptor =
+      aController->PendingPullIntos().getFirst();
+
+  // Step 2.
+  JS::Rooted<JSObject*> buffer(aCx, firstDescriptor->Buffer());
+#ifdef DEBUG
+  bool canTransferBuffer = CanTransferArrayBuffer(aCx, buffer, aRv);
+  MOZ_ASSERT(!aRv.Failed());
+  MOZ_ASSERT(canTransferBuffer);
+#endif
+
+  // Step 3.
+  ReadableByteStreamControllerInvalidateBYOBRequest(aController);
+
+  // Step 4.
+  auto state = aController->Stream()->State();
+
+  // Step 5.
+  if (state == ReadableStream::ReaderState::Closed) {
+    // Step 5.1
+    MOZ_ASSERT(aBytesWritten == 0);
+
+    // Step 5.2
+    ReadableByteStreamControllerRespondInClosedState(aCx, aController,
+                                                     firstDescriptor, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+  } else {
+    // Step 6.1
+    MOZ_ASSERT(state == ReadableStream::ReaderState::Readable);
+
+    // Step 6.2.
+    MOZ_ASSERT(aBytesWritten > 0);
+
+    // Step 6.3
+    ReadableByteStreamControllerRespondInReadableState(
+        aCx, aController, aBytesWritten, firstDescriptor, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+  }
+  // Step 7.
+  ReadableByteStreamControllerCallPullIfNeeded(aCx, aController, aRv);
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-respond
+void ReadableByteStreamControllerRespond(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    uint64_t aBytesWritten, ErrorResult& aRv) {
+  // Step 1.
+  MOZ_ASSERT(!aController->PendingPullIntos().isEmpty());
+
+  // Step 2.
+  PullIntoDescriptor* firstDescriptor =
+      aController->PendingPullIntos().getFirst();
+
+  // Step 3.
+  auto state = aController->Stream()->State();
+
+  // Step 4.
+  if (state == ReadableStream::ReaderState::Closed) {
+    // Step 4.1
+    if (aBytesWritten != 0) {
+      aRv.ThrowTypeError("bytesWritten not zero on closed stream");
+      return;
+    }
+  } else {
+    // Step 5.1
+    MOZ_ASSERT(state == ReadableStream::ReaderState::Readable);
+
+    // Step 5.2
+    if (aBytesWritten == 0) {
+      aRv.ThrowTypeError("bytesWritten 0");
+      return;
+    }
+
+    // Step 5.3
+    if (firstDescriptor->BytesFilled() + aBytesWritten >
+        firstDescriptor->ByteLength()) {
+      aRv.ThrowRangeError("bytesFilled + bytesWritten > byteLength");
+      return;
+    }
+  }
+
+  // Step 6.
+  aRv.MightThrowJSException();
+  JS::Rooted<JSObject*> buffer(aCx, firstDescriptor->Buffer());
+  JS::Rooted<JSObject*> transferredBuffer(aCx,
+                                          TransferArrayBuffer(aCx, buffer));
+  if (!transferredBuffer) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return;
+  }
+  firstDescriptor->SetBuffer(transferredBuffer);
+
+  // Step 7.
+  ReadableByteStreamControllerRespondInternal(aCx, aController, aBytesWritten,
+                                              aRv);
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-respond-with-new-view
+void ReadableByteStreamControllerRespondWithNewView(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    JS::Handle<JSObject*> aView, ErrorResult& aRv) {
+  aRv.MightThrowJSException();
+
+  // Step 1.
+  MOZ_ASSERT(!aController->PendingPullIntos().isEmpty());
+
+  // Step 2.
+  bool isSharedMemory;
+  JS::Rooted<JSObject*> viewedArrayBuffer(
+      aCx, JS_GetArrayBufferViewBuffer(aCx, aView, &isSharedMemory));
+  if (!viewedArrayBuffer) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return;
+  }
+  MOZ_ASSERT(!JS::IsDetachedArrayBufferObject(viewedArrayBuffer));
+
+  // Step 3.
+  RefPtr<PullIntoDescriptor> firstDescriptor =
+      aController->PendingPullIntos().getFirst();
+
+  // Step 4.
+  ReadableStream::ReaderState state = aController->Stream()->State();
+
+  // Step 5.
+  if (state == ReadableStream::ReaderState::Closed) {
+    // Step 5.1
+    if (JS_GetArrayBufferViewByteLength(aView) != 0) {
+      aRv.ThrowTypeError("View has non-zero length in closed stream");
+      return;
+    }
+  } else {
+    // Step 6.1
+    MOZ_ASSERT(state == ReadableStream::ReaderState::Readable);
+
+    // Step 6.2
+    if (JS_GetArrayBufferViewByteLength(aView) == 0) {
+      aRv.ThrowTypeError("View has zero length in readable stream");
+      return;
+    }
+  }
+
+  // Step 7.
+  if (firstDescriptor->ByteOffset() + firstDescriptor->BytesFilled() !=
+      JS_GetArrayBufferViewByteOffset(aView)) {
+    aRv.ThrowRangeError("Invalid Offset");
+    return;
+  }
+
+  // Step 8.
+  if (firstDescriptor->BufferByteLength() !=
+      JS::GetArrayBufferByteLength(viewedArrayBuffer)) {
+    aRv.ThrowRangeError("Mismatched buffer byte lengths");
+    return;
+  }
+
+  // Step 9.
+  if (firstDescriptor->BytesFilled() + JS_GetArrayBufferViewByteLength(aView) >
+      firstDescriptor->ByteLength()) {
+    aRv.ThrowRangeError("Too many bytes");
+    return;
+  }
+
+  // Step 10. Let viewByteLength be view.[[ByteLength]].
+  size_t viewByteLength = JS_GetArrayBufferViewByteLength(aView);
+
+  // Step 11. Set firstDescriptor’s buffer to ?
+  // TransferArrayBuffer(view.[[ViewedArrayBuffer]]).
+  JS::Rooted<JSObject*> transferedBuffer(
+      aCx, TransferArrayBuffer(aCx, viewedArrayBuffer));
+  if (!transferedBuffer) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return;
+  }
+  firstDescriptor->SetBuffer(transferedBuffer);
+
+  // Step 12. Perform ? ReadableByteStreamControllerRespondInternal(controller,
+  // viewByteLength).
+  ReadableByteStreamControllerRespondInternal(aCx, aController, viewByteLength,
+                                              aRv);
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-fill-pull-into-descriptor-from-queue
+bool ReadableByteStreamControllerFillPullIntoDescriptorFromQueue(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    PullIntoDescriptor* aPullIntoDescriptor, ErrorResult& aRv) {
+  // Step 1. Let elementSize be pullIntoDescriptor.[[elementSize]].
+  size_t elementSize = aPullIntoDescriptor->ElementSize();
+
+  // Step 2. Let currentAlignedBytes be pullIntoDescriptor’s bytes filled −
+  // (pullIntoDescriptor’s bytes filled mod elementSize).
+  size_t currentAlignedBytes =
+      aPullIntoDescriptor->BytesFilled() -
+      (aPullIntoDescriptor->BytesFilled() % elementSize);
+
+  // Step 3. Let maxBytesToCopy be min(controller.[[queueTotalSize]],
+  // pullIntoDescriptor’s byte length − pullIntoDescriptor’s bytes filled).
+  size_t maxBytesToCopy =
+      std::min(static_cast<size_t>(aController->QueueTotalSize()),
+               static_cast<size_t>((aPullIntoDescriptor->ByteLength() -
+                                    aPullIntoDescriptor->BytesFilled())));
+
+  // Step 4. Let maxBytesFilled be pullIntoDescriptor’s bytes filled +
+  // maxBytesToCopy.
+  size_t maxBytesFilled = aPullIntoDescriptor->BytesFilled() + maxBytesToCopy;
+
+  // Step 5. Let maxAlignedBytes be maxBytesFilled − (maxBytesFilled mod
+  // elementSize).
+  size_t maxAlignedBytes = maxBytesFilled - (maxBytesFilled % elementSize);
+
+  // Step 6. Let totalBytesToCopyRemaining be maxBytesToCopy.
+  size_t totalBytesToCopyRemaining = maxBytesToCopy;
+
+  // Step 7. Let ready be false.
+  bool ready = false;
+
+  // Step 8. If maxAlignedBytes > currentAlignedBytes,
+  if (maxAlignedBytes > currentAlignedBytes) {
+    // Step 8.1. Set totalBytesToCopyRemaining to maxAlignedBytes −
+    // pullIntoDescriptor’s bytes filled.
+    totalBytesToCopyRemaining =
+        maxAlignedBytes - aPullIntoDescriptor->BytesFilled();
+    // Step 8.2. Set ready to true.
+    ready = true;
+  }
+
+  // Step 9. Let queue be controller.[[queue]].
+  LinkedList<RefPtr<ReadableByteStreamQueueEntry>>& queue =
+      aController->Queue();
+
+  // Step 10. While totalBytesToCopyRemaining > 0,
+  while (totalBytesToCopyRemaining > 0) {
+    // Step 10.1  Let headOfQueue be queue[0].
+    ReadableByteStreamQueueEntry* headOfQueue = queue.getFirst();
+
+    // Step 10.2. Let bytesToCopy be min(totalBytesToCopyRemaining,
+    // headOfQueue’s byte length).
+    size_t bytesToCopy =
+        std::min(totalBytesToCopyRemaining, headOfQueue->ByteLength());
+
+    // Step 10.3. Let destStart be pullIntoDescriptor’s byte offset +
+    // pullIntoDescriptor’s bytes filled.
+    size_t destStart =
+        aPullIntoDescriptor->ByteOffset() + aPullIntoDescriptor->BytesFilled();
+
+    // Step 10.4. Perform !CopyDataBlockBytes(pullIntoDescriptor’s
+    //            buffer.[[ArrayBufferData]], destStart, headOfQueue’s
+    //            buffer.[[ArrayBufferData]], headOfQueue’s byte offset,
+    //            bytesToCopy).
+    JS::Rooted<JSObject*> descriptorBuffer(aCx, aPullIntoDescriptor->Buffer());
+    JS::Rooted<JSObject*> queueBuffer(aCx, headOfQueue->Buffer());
+    if (!JS::ArrayBufferCopyData(aCx, descriptorBuffer, destStart, queueBuffer,
+                                 headOfQueue->ByteOffset(), bytesToCopy)) {
+      aRv.StealExceptionFromJSContext(aCx);
+      return false;
+    }
+
+    // Step 10.5. If headOfQueue’s byte length is bytesToCopy,
+    if (headOfQueue->ByteLength() == bytesToCopy) {
+      // Step 10.5.1. Remove queue[0].
+      queue.popFirst();
+    } else {
+      // Step 10.6.  Otherwise,
+
+      // Step 10.6.1 Set headOfQueue’s byte offset to
+      // headOfQueue’s byte offset +  bytesToCopy.
+      headOfQueue->SetByteOffset(headOfQueue->ByteOffset() + bytesToCopy);
+      // Step 10.6.2  Set headOfQueue’s byte length to
+      // headOfQueue’s byte length − bytesToCopy.
+      headOfQueue->SetByteLength(headOfQueue->ByteLength() - bytesToCopy);
+    }
+
+    // Step 10.7. Set controller.[[queueTotalSize]] to
+    // controller.[[queueTotalSize]] −  bytesToCopy.
+    aController->SetQueueTotalSize(aController->QueueTotalSize() -
+                                   (double)bytesToCopy);
+
+    // Step 10.8, Perform
+    // !ReadableByteStreamControllerFillHeadPullIntoDescriptor(controller,
+    //     bytesToCopy, pullIntoDescriptor).
+    ReadableByteStreamControllerFillHeadPullIntoDescriptor(
+        aController, bytesToCopy, aPullIntoDescriptor);
+
+    // Step 10.9. Set totalBytesToCopyRemaining to totalBytesToCopyRemaining −
+    //     bytesToCopy.
+    totalBytesToCopyRemaining = totalBytesToCopyRemaining - bytesToCopy;
+  }
+
+  // Step 11. If ready is false,
+  if (!ready) {
+    // Step 11.1. Assert: controller.[[queueTotalSize]] is 0.
+    MOZ_ASSERT(aController->QueueTotalSize() == 0);
+
+    // Step 11.2. Assert: pullIntoDescriptor’s bytes filled > 0.
+    MOZ_ASSERT(aPullIntoDescriptor->BytesFilled() > 0);
+
+    // Step 11.3. Assert: pullIntoDescriptor’s bytes filled <
+    // pullIntoDescriptor’s
+    //     element size.
+    MOZ_ASSERT(aPullIntoDescriptor->BytesFilled() <
+               aPullIntoDescriptor->ElementSize());
+  }
+
+  // Step 12. Return ready.
+  return ready;
+}
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-pull-into
+void ReadableByteStreamControllerPullInto(
+    JSContext* aCx, ReadableByteStreamController* aController,
+    JS::Handle<JSObject*> aView, ReadIntoRequest* aReadIntoRequest,
+    ErrorResult& aRv) {
+  aRv.MightThrowJSException();
+
+  // Step 1. Let stream be controller.[[stream]].
+  ReadableStream* stream = aController->Stream();
+
+  // Step 2. Let elementSize be 1.
+  size_t elementSize = 1;
+
+  // Step 3. Let ctor be %DataView%.
+  PullIntoDescriptor::Constructor ctor =
+      PullIntoDescriptor::Constructor::DataView;
+
+  // Step 4. If view has a [[TypedArrayName]] internal slot (i.e., it is not a
+  // DataView),
+  if (JS_IsTypedArrayObject(aView)) {
+    // Step 4.1. Set elementSize to the element size specified in the typed
+    // array constructors table for view.[[TypedArrayName]].
+    JS::Scalar::Type type = JS_GetArrayBufferViewType(aView);
+    elementSize = JS::Scalar::byteSize(type);
+
+    // Step 4.2 Set ctor to the constructor specified in the typed array
+    // constructors table for view.[[TypedArrayName]].
+    ctor = PullIntoDescriptor::constructorFromScalar(type);
+  }
+
+  // Step 5. Let byteOffset be view.[[ByteOffset]].
+  size_t byteOffset = JS_GetArrayBufferViewByteOffset(aView);
+
+  // Step 6. Let byteLength be view.[[ByteLength]].
+  size_t byteLength = JS_GetArrayBufferViewByteLength(aView);
+
+  // Step 7. Let bufferResult be
+  // TransferArrayBuffer(view.[[ViewedArrayBuffer]]).
+  bool isShared;
+  JS::Rooted<JSObject*> viewedArrayBuffer(
+      aCx, JS_GetArrayBufferViewBuffer(aCx, aView, &isShared));
+  if (!viewedArrayBuffer) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return;
+  }
+  JS::Rooted<JSObject*> bufferResult(
+      aCx, TransferArrayBuffer(aCx, viewedArrayBuffer));
+
+  // Step 8. If bufferResult is an abrupt completion,
+  if (!bufferResult) {
+    JS::Rooted<JS::Value> pendingException(aCx);
+    if (!JS_GetPendingException(aCx, &pendingException)) {
+      // This means an un-catchable exception. Use StealExceptionFromJSContext
+      // to setup aRv properly.
+      aRv.StealExceptionFromJSContext(aCx);
+      return;
+    }
+
+    // It's not expliclitly stated, but I assume the intention here is that
+    // we perform a normal completion here; we also need to clear the
+    // exception state anyhow to succesfully run ErrorSteps.
+    JS_ClearPendingException(aCx);
+
+    //     Step 8.1. Perform readIntoRequest’s error steps, given
+    //     bufferResult.[[Value]].
+    aReadIntoRequest->ErrorSteps(aCx, pendingException, aRv);
+
+    //     Step 8.2. Return.
+    return;
+  }
+
+  // Step 9. Let buffer be bufferResult.[[Value]].
+  JS::Rooted<JSObject*> buffer(aCx, bufferResult);
+
+  // Step 10. Let pullIntoDescriptor be a new pull-into descriptor with
+  //  buffer: buffer,
+  //  buffer byte length:  buffer.[[ArrayBufferByteLength]],
+  //  byte offset: byteOffset,
+  //  byte length: byteLength,
+  //  bytes filled: 0,
+  //  element size: elementSize,
+  //  view constructor: ctor,
+  //  and reader type: "byob".
+  RefPtr<PullIntoDescriptor> pullIntoDescriptor = new PullIntoDescriptor(
+      buffer, JS::GetArrayBufferByteLength(buffer), byteOffset, byteLength, 0,
+      elementSize, ctor, ReaderType::BYOB);
+
+  // Step 11. If controller.[[pendingPullIntos]] is not empty,
+  if (!aController->PendingPullIntos().isEmpty()) {
+    // Step 11.1. Append pullIntoDescriptor to controller.[[pendingPullIntos]].
+    aController->PendingPullIntos().insertBack(pullIntoDescriptor);
+
+    // Step 11.2. Perform !ReadableStreamAddReadIntoRequest(stream,
+    // readIntoRequest).
+    ReadableStreamAddReadIntoRequest(stream, aReadIntoRequest);
+
+    // Step 11.3. Return.
+    return;
+  }
+
+  // Step 12. If stream.[[state]] is "closed",
+  if (stream->State() == ReadableStream::ReaderState::Closed) {
+    // Step 12.1. Let emptyView be !Construct(ctor, « pullIntoDescriptor’s
+    //            buffer, pullIntoDescriptor’s byte offset, 0 »).
+    JS::Rooted<JSObject*> pullIntoBuffer(aCx, pullIntoDescriptor->Buffer());
+    JS::Rooted<JSObject*> emptyView(
+        aCx,
+        ConstructFromPullIntoConstructor(aCx, ctor, pullIntoBuffer,
+                                         pullIntoDescriptor->ByteOffset(), 0));
+    if (!emptyView) {
+      aRv.StealExceptionFromJSContext(aCx);
+      return;
+    }
+
+    // Step 12.2. Perform readIntoRequest’s close steps, given emptyView.
+    JS::Rooted<JS::Value> emptyViewValue(aCx, JS::ObjectValue(*emptyView));
+    aReadIntoRequest->CloseSteps(aCx, emptyViewValue, aRv);
+
+    // Step 12.3. Return.
+    return;
+  }
+
+  // Step 13,. If controller.[[queueTotalSize]] > 0,
+  if (aController->QueueTotalSize() > 0) {
+    // Step 13.1 If
+    // !ReadableByteStreamControllerFillPullIntoDescriptorFromQueue(controller,
+    //     pullIntoDescriptor) is true,
+    bool ready = ReadableByteStreamControllerFillPullIntoDescriptorFromQueue(
+        aCx, aController, pullIntoDescriptor, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+    if (ready) {
+      // Step 13.1.1  Let filledView be
+      //         !ReadableByteStreamControllerConvertPullIntoDescriptor(pullIntoDescriptor).
+      JS::Rooted<JSObject*> filledView(
+          aCx, ReadableByteStreamControllerConvertPullIntoDescriptor(
+                   aCx, pullIntoDescriptor, aRv));
+      if (aRv.Failed()) {
+        return;
+      }
+      //  Step 13.1.2. Perform
+      //         !ReadableByteStreamControllerHandleQueueDrain(controller).
+      ReadableByteStreamControllerHandleQueueDrain(aCx, aController, aRv);
+      if (aRv.Failed()) {
+        return;
+      }
+      // Step 13.1.3.  Perform readIntoRequest’s chunk steps, given filledView.
+      JS::Rooted<JS::Value> filledViewValue(aCx, JS::ObjectValue(*filledView));
+      aReadIntoRequest->ChunkSteps(aCx, filledViewValue, aRv);
+      // Step 13.1.4.   Return.
+      return;
+    }
+
+    // Step 13.2  If controller.[[closeRequested]] is true,
+    if (aController->CloseRequested()) {
+      // Step 13.2.1.   Let e be a TypeError exception.
+      ErrorResult typeError;
+      typeError.ThrowTypeError("Close Requested True during Pull Into");
+
+      JS::Rooted<JS::Value> e(aCx);
+      MOZ_RELEASE_ASSERT(ToJSValue(aCx, std::move(typeError), &e));
+
+      // Step 13.2.2. Perform !ReadableByteStreamControllerError(controller, e).
+      ReadableByteStreamControllerError(aController, e, aRv);
+      if (aRv.Failed()) {
+        return;
+      }
+
+      // Step 13.2.3. Perform readIntoRequest’s error steps, given e.
+      aReadIntoRequest->ErrorSteps(aCx, e, aRv);
+
+      // Step 13.2.4.  Return.
+      return;
+    }
+  }
+
+  // Step 14. Append pullIntoDescriptor to controller.[[pendingPullIntos]].
+  aController->PendingPullIntos().insertBack(pullIntoDescriptor);
+
+  // Step 15. Perform !ReadableStreamAddReadIntoRequest(stream,
+  // readIntoRequest).
+  ReadableStreamAddReadIntoRequest(stream, aReadIntoRequest);
+
+  // Step 16, Perform
+  // !ReadableByteStreamControllerCallPullIfNeeded(controller).
+  ReadableByteStreamControllerCallPullIfNeeded(aCx, aController, aRv);
+}
+
+// https://streams.spec.whatwg.org/#set-up-readable-byte-stream-controller
+void SetUpReadableByteStreamController(
+    JSContext* aCx, ReadableStream* aStream,
+    ReadableByteStreamController* aController,
+    UnderlyingSourceAlgorithmsBase* aAlgorithms, double aHighWaterMark,
+    Maybe<uint64_t> aAutoAllocateChunkSize, ErrorResult& aRv) {
+  // Step 1. Assert: stream.[[controller]] is undefined.
+  MOZ_ASSERT(!aStream->Controller());
+
+  // Step 2. If autoAllocateChunkSize is not undefined,
+  // Step 2.1. Assert: ! IsInteger(autoAllocateChunkSize) is true. Implicit
+  // Step 2.2. Assert: autoAllocateChunkSize is positive. (Implicit by
+  //           type.)
+
+  // Step 3. Set controller.[[stream]] to stream.
+  aController->SetStream(aStream);
+
+  // Step 4. Set controller.[[pullAgain]] and controller.[[pulling]] to false.
+  aController->SetPullAgain(false);
+  aController->SetPulling(false);
+
+  // Step 5. Set controller.[[byobRequest]] to null.
+  aController->SetByobRequest(nullptr);
+
+  // Step 6. Perform !ResetQueue(controller).
+  ResetQueue(aController);
+
+  // Step 7. Set controller.[[closeRequested]] and controller.[[started]] to
+  // false.
+  aController->SetCloseRequested(false);
+  aController->SetStarted(false);
+
+  // Step 8. Set controller.[[strategyHWM]] to highWaterMark.
+  aController->SetStrategyHWM(aHighWaterMark);
+
+  // Step 9. Set controller.[[pullAlgorithm]] to pullAlgorithm.
+  // Step 10. Set controller.[[cancelAlgorithm]] to cancelAlgorithm.
+  aController->SetAlgorithms(*aAlgorithms);
+
+  // Step 11. Set controller.[[autoAllocateChunkSize]] to autoAllocateChunkSize.
+  aController->SetAutoAllocateChunkSize(aAutoAllocateChunkSize);
+
+  // Step 12. Set controller.[[pendingPullIntos]] to a new empty list.
+  aController->PendingPullIntos().clear();
+
+  // Step 13. Set stream.[[controller]] to controller.
+  aStream->SetController(*aController);
+
+  // Step 14. Let startResult be the result of performing startAlgorithm.
+  JS::Rooted<JS::Value> startResult(aCx, JS::UndefinedValue());
+  RefPtr<ReadableStreamController> controller = aController;
+  aAlgorithms->StartCallback(aCx, *controller, &startResult, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Let startPromise be a promise resolved with startResult.
+  RefPtr<Promise> startPromise =
+      Promise::CreateInfallible(aStream->GetParentObject());
+  startPromise->MaybeResolve(startResult);
+
+  // Step 16+17
+  startPromise->AddCallbacksWithCycleCollectedArgs(
+      [](JSContext* aCx, JS::Handle<JS::Value> aValue, ErrorResult& aRv,
+         ReadableByteStreamController* aController)
+          MOZ_CAN_RUN_SCRIPT_BOUNDARY {
+            MOZ_ASSERT(aController);
+
+            // Step 16.1
+            aController->SetStarted(true);
+
+            // Step 16.2
+            aController->SetPulling(false);
+
+            // Step 16.3
+            aController->SetPullAgain(false);
+
+            // Step 16.4:
+            ReadableByteStreamControllerCallPullIfNeeded(
+                aCx, MOZ_KnownLive(aController), aRv);
+          },
+      [](JSContext* aCx, JS::Handle<JS::Value> aValue, ErrorResult& aRv,
+         ReadableByteStreamController* aController) {
+        // Step 17.1
+        ReadableByteStreamControllerError(aController, aValue, aRv);
+      },
+      RefPtr(aController));
+}
+
+// https://streams.spec.whatwg.org/#set-up-readable-byte-stream-controller-from-underlying-source
+void SetUpReadableByteStreamControllerFromUnderlyingSource(
+    JSContext* aCx, ReadableStream* aStream,
+    JS::Handle<JSObject*> aUnderlyingSource,
+    UnderlyingSource& aUnderlyingSourceDict, double aHighWaterMark,
+    ErrorResult& aRv) {
+  // Step 1. Let controller be a new ReadableByteStreamController.
+  auto controller =
+      MakeRefPtr<ReadableByteStreamController>(aStream->GetParentObject());
+
+  // Step 2 - 7
+  auto algorithms = MakeRefPtr<UnderlyingSourceAlgorithms>(
+      aStream->GetParentObject(), aUnderlyingSource, aUnderlyingSourceDict);
+
+  // Step 8. Let autoAllocateChunkSize be
+  // underlyingSourceDict["autoAllocateChunkSize"], if it exists, or undefined
+  // otherwise.
+  Maybe<uint64_t> autoAllocateChunkSize = mozilla::Nothing();
+  if (aUnderlyingSourceDict.mAutoAllocateChunkSize.WasPassed()) {
+    uint64_t value = aUnderlyingSourceDict.mAutoAllocateChunkSize.Value();
+    // Step 9. If autoAllocateChunkSize is 0, then throw a TypeError
+    // exception.
+    if (value == 0) {
+      aRv.ThrowTypeError("autoAllocateChunkSize can not be zero.");
+      return;
+    }
+    autoAllocateChunkSize = mozilla::Some(value);
+  }
+
+  // Step 10. Perform ? SetUpReadableByteStreamController(stream, controller,
+  // startAlgorithm, pullAlgorithm, cancelAlgorithm, highWaterMark,
+  // autoAllocateChunkSize).
+  SetUpReadableByteStreamController(aCx, aStream, controller, algorithms,
+                                    aHighWaterMark, autoAllocateChunkSize, aRv);
+}
+
+}  // namespace streams_abstract
+
+}  // namespace mozilla::dom