gecko-dev/dom/ipc/StructuredCloneData.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "StructuredCloneData.h"

#include "mozilla/dom/BindingUtils.h"
#include "mozilla/dom/BlobBinding.h"
#include "mozilla/dom/BlobImpl.h"
#include "mozilla/dom/DOMTypes.h"
#include "mozilla/dom/File.h"
#include "mozilla/dom/IPCBlobUtils.h"
#include "mozilla/ipc/BackgroundParent.h"
#include "mozilla/ipc/IPCStreamUtils.h"
#include "mozilla/ipc/SerializedStructuredCloneBuffer.h"
#include "nsContentUtils.h"
#include "nsJSEnvironment.h"
#include "MainThreadUtils.h"
#include "StructuredCloneTags.h"
#include "jsapi.h"

using namespace mozilla::ipc;

namespace mozilla::dom::ipc {

using mozilla::ipc::IPCStream;
using mozilla::ipc::PBackgroundChild;
using mozilla::ipc::PBackgroundParent;

StructuredCloneData::StructuredCloneData()
    : StructuredCloneData(
          StructuredCloneHolder::StructuredCloneScope::DifferentProcess,
          StructuredCloneHolder::TransferringSupported) {}

StructuredCloneData::StructuredCloneData(StructuredCloneData&& aOther)
    : StructuredCloneData(
          StructuredCloneHolder::StructuredCloneScope::DifferentProcess,
          StructuredCloneHolder::TransferringSupported) {
  *this = std::move(aOther);
}

StructuredCloneData::StructuredCloneData(
    StructuredCloneHolder::StructuredCloneScope aScope,
    TransferringSupport aSupportsTransferring)
    : StructuredCloneHolder(StructuredCloneHolder::CloningSupported,
                            aSupportsTransferring, aScope),
      mExternalData(JS::StructuredCloneScope::DifferentProcess),
      mInitialized(false) {
  MOZ_ASSERT(
      aScope == StructuredCloneHolder::StructuredCloneScope::DifferentProcess ||
      aScope ==
          StructuredCloneHolder::StructuredCloneScope::UnknownDestination);
}

StructuredCloneData::~StructuredCloneData() = default;

StructuredCloneData& StructuredCloneData::operator=(
    StructuredCloneData&& aOther) {
  mBlobImplArray = std::move(aOther.mBlobImplArray);
  mExternalData = std::move(aOther.mExternalData);
  mSharedData = std::move(aOther.mSharedData);
  mPortIdentifiers = std::move(aOther.mPortIdentifiers);
  mInitialized = aOther.mInitialized;

  return *this;
}

bool StructuredCloneData::Copy(const StructuredCloneData& aData) {
  if (!aData.mInitialized) {
    return true;
  }

  if (aData.SharedData()) {
    mSharedData = aData.SharedData();
  } else {
    mSharedData = SharedJSAllocatedData::CreateFromExternalData(aData.Data());
    NS_ENSURE_TRUE(mSharedData, false);
  }

  if (mSupportsTransferring) {
    PortIdentifiers().AppendElements(aData.PortIdentifiers());
  }

  MOZ_ASSERT(BlobImpls().IsEmpty());
  BlobImpls().AppendElements(aData.BlobImpls());

  MOZ_ASSERT(GetSurfaces().IsEmpty());
  MOZ_ASSERT(WasmModules().IsEmpty());

  MOZ_ASSERT(InputStreams().IsEmpty());
  InputStreams().AppendElements(aData.InputStreams());

  mInitialized = true;

  return true;
}

void StructuredCloneData::Read(JSContext* aCx,
                               JS::MutableHandle<JS::Value> aValue,
                               ErrorResult& aRv) {
  Read(aCx, aValue, JS::CloneDataPolicy(), aRv);
}

void StructuredCloneData::Read(JSContext* aCx,
                               JS::MutableHandle<JS::Value> aValue,
                               const JS::CloneDataPolicy& aCloneDataPolicy,
                               ErrorResult& aRv) {
  MOZ_ASSERT(mInitialized);

  nsIGlobalObject* global = xpc::CurrentNativeGlobal(aCx);
  MOZ_ASSERT(global);

  ReadFromBuffer(global, aCx, Data(), aValue, aCloneDataPolicy, aRv);
}

void StructuredCloneData::Write(JSContext* aCx, JS::Handle<JS::Value> aValue,
                                ErrorResult& aRv) {
  Write(aCx, aValue, JS::UndefinedHandleValue, JS::CloneDataPolicy(), aRv);
}

void StructuredCloneData::Write(JSContext* aCx, JS::Handle<JS::Value> aValue,
                                JS::Handle<JS::Value> aTransfer,
                                const JS::CloneDataPolicy& aCloneDataPolicy,
                                ErrorResult& aRv) {
  MOZ_ASSERT(!mInitialized);

  StructuredCloneHolder::Write(aCx, aValue, aTransfer, aCloneDataPolicy, aRv);
  if (NS_WARN_IF(aRv.Failed())) {
    return;
  }

  JSStructuredCloneData data(mBuffer->scope());
  mBuffer->giveTo(&data);
  mBuffer = nullptr;
  mSharedData = new SharedJSAllocatedData(std::move(data));
  mInitialized = true;
}

bool StructuredCloneData::BuildClonedMessageData(
    ClonedMessageData& aClonedData) {
  SerializedStructuredCloneBuffer& buffer = aClonedData.data();
  auto iter = Data().Start();
  size_t size = Data().Size();
  bool success;
  buffer.data = Data().Borrow(iter, size, &success);
  if (NS_WARN_IF(!success)) {
    return false;
  }
  if (SupportsTransferring()) {
    aClonedData.identifiers().AppendElements(PortIdentifiers());
  }

  const nsTArray<RefPtr<BlobImpl>>& blobImpls = BlobImpls();

  if (!blobImpls.IsEmpty()) {
    if (NS_WARN_IF(
            !aClonedData.blobs().SetLength(blobImpls.Length(), fallible))) {
      return false;
    }

    for (uint32_t i = 0; i < blobImpls.Length(); ++i) {
      nsresult rv =
          IPCBlobUtils::Serialize(blobImpls[i], aClonedData.blobs()[i]);
      if (NS_WARN_IF(NS_FAILED(rv))) {
        return false;
      }
    }
  }

  const nsTArray<nsCOMPtr<nsIInputStream>>& inputStreams = InputStreams();
  if (!inputStreams.IsEmpty()) {
    nsTArray<IPCStream>& streams = aClonedData.inputStreams();
    uint32_t length = inputStreams.Length();
    streams.SetCapacity(length);
    for (uint32_t i = 0; i < length; ++i) {
      IPCStream value;
      if (!mozilla::ipc::SerializeIPCStream(do_AddRef(inputStreams[i]), value,
                                            /* aAllowLazy */ false)) {
        return false;
      }
      streams.AppendElement(value);
    }
  }

  return true;
}

// See the StructuredCloneData class block comment for the meanings of each val.
enum MemoryFlavorEnum { BorrowMemory = 0, CopyMemory, StealMemory };

template <MemoryFlavorEnum>
struct MemoryTraits {};

template <>
struct MemoryTraits<BorrowMemory> {
  using ClonedMessageType = const mozilla::dom::ClonedMessageData;

  static void ProvideBuffer(const ClonedMessageData& aClonedData,
                            StructuredCloneData& aData) {
    const SerializedStructuredCloneBuffer& buffer = aClonedData.data();
    aData.UseExternalData(buffer.data);
  }
};

template <>
struct MemoryTraits<CopyMemory> {
  using ClonedMessageType = const mozilla::dom::ClonedMessageData;

  static void ProvideBuffer(const ClonedMessageData& aClonedData,
                            StructuredCloneData& aData) {
    const SerializedStructuredCloneBuffer& buffer = aClonedData.data();
    aData.CopyExternalData(buffer.data);
  }
};

template <>
struct MemoryTraits<StealMemory> {
  // note: not const!
  using ClonedMessageType = mozilla::dom::ClonedMessageData;

  static void ProvideBuffer(ClonedMessageData& aClonedData,
                            StructuredCloneData& aData) {
    SerializedStructuredCloneBuffer& buffer = aClonedData.data();
    aData.StealExternalData(buffer.data);
  }
};

// Note that there isn't actually a difference between Parent/BackgroundParent
// and Child/BackgroundChild in this implementation.  The calling methods,
// however, do maintain the distinction for code-reading purposes and are backed
// by assertions to enforce there is no misuse.
template <MemoryFlavorEnum MemoryFlavor>
static void UnpackClonedMessageData(
    typename MemoryTraits<MemoryFlavor>::ClonedMessageType& aClonedData,
    StructuredCloneData& aData) {
  const nsTArray<MessagePortIdentifier>& identifiers =
      aClonedData.identifiers();

  MemoryTraits<MemoryFlavor>::ProvideBuffer(aClonedData, aData);

  if (aData.SupportsTransferring()) {
    aData.PortIdentifiers().AppendElements(identifiers);
  }

  const nsTArray<IPCBlob>& blobs = aClonedData.blobs();
  if (!blobs.IsEmpty()) {
    uint32_t length = blobs.Length();
    aData.BlobImpls().SetCapacity(length);
    for (uint32_t i = 0; i < length; ++i) {
      RefPtr<BlobImpl> blobImpl = IPCBlobUtils::Deserialize(blobs[i]);
      MOZ_ASSERT(blobImpl);

      aData.BlobImpls().AppendElement(blobImpl);
    }
  }

  const nsTArray<IPCStream>& streams = aClonedData.inputStreams();
  if (!streams.IsEmpty()) {
    uint32_t length = streams.Length();
    aData.InputStreams().SetCapacity(length);
    for (uint32_t i = 0; i < length; ++i) {
      nsCOMPtr<nsIInputStream> stream = DeserializeIPCStream(streams[i]);
      aData.InputStreams().AppendElement(stream);
    }
  }
}

void StructuredCloneData::BorrowFromClonedMessageData(
    const ClonedMessageData& aClonedData) {
  UnpackClonedMessageData<BorrowMemory>(aClonedData, *this);
}

void StructuredCloneData::CopyFromClonedMessageData(
    const ClonedMessageData& aClonedData) {
  UnpackClonedMessageData<CopyMemory>(aClonedData, *this);
}

void StructuredCloneData::StealFromClonedMessageData(
    ClonedMessageData& aClonedData) {
  UnpackClonedMessageData<StealMemory>(aClonedData, *this);
}

void StructuredCloneData::WriteIPCParams(IPC::MessageWriter* aWriter) const {
  WriteParam(aWriter, Data());
}

bool StructuredCloneData::ReadIPCParams(IPC::MessageReader* aReader) {
  MOZ_ASSERT(!mInitialized);
  JSStructuredCloneData data(JS::StructuredCloneScope::DifferentProcess);
  if (!ReadParam(aReader, &data)) {
    return false;
  }
  mSharedData = new SharedJSAllocatedData(std::move(data));
  mInitialized = true;
  return true;
}

bool StructuredCloneData::CopyExternalData(const char* aData,
                                           size_t aDataLength) {
  MOZ_ASSERT(!mInitialized);
  mSharedData =
      SharedJSAllocatedData::CreateFromExternalData(aData, aDataLength);
  NS_ENSURE_TRUE(mSharedData, false);
  mInitialized = true;
  return true;
}

bool StructuredCloneData::CopyExternalData(const JSStructuredCloneData& aData) {
  MOZ_ASSERT(!mInitialized);
  mSharedData = SharedJSAllocatedData::CreateFromExternalData(aData);
  NS_ENSURE_TRUE(mSharedData, false);
  mInitialized = true;
  return true;
}

bool StructuredCloneData::StealExternalData(JSStructuredCloneData& aData) {
  MOZ_ASSERT(!mInitialized);
  mSharedData = new SharedJSAllocatedData(std::move(aData));
  mInitialized = true;
  return true;
}

already_AddRefed<SharedJSAllocatedData> StructuredCloneData::TakeSharedData() {
  return mSharedData.forget();
}

}  // namespace mozilla::dom::ipc