IPCStreamDestination.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 "IPCStreamDestination.h"
#include "mozilla/InputStreamLengthWrapper.h"
#include "mozilla/Mutex.h"
#include "nsIAsyncInputStream.h"
#include "nsIAsyncOutputStream.h"
#include "nsIBufferedStreams.h"
#include "nsICloneableInputStream.h"
#include "nsIPipe.h"
#include "nsThreadUtils.h"
#include "mozilla/webrender/WebRenderTypes.h"

namespace mozilla {
namespace ipc {

// ----------------------------------------------------------------------------
// IPCStreamDestination::DelayedStartInputStream
//
// When AutoIPCStream is used with delayedStart, we need to ask for data at the
// first real use of the nsIInputStream. In order to do so, we wrap the
// nsIInputStream, created by the nsIPipe, with this wrapper.

class IPCStreamDestination::DelayedStartInputStream final
    : public nsIAsyncInputStream,
      public nsIInputStreamCallback,
      public nsISearchableInputStream,
      public nsICloneableInputStream,
      public nsIBufferedInputStream {
 public:
  NS_DECL_THREADSAFE_ISUPPORTS

  DelayedStartInputStream(IPCStreamDestination* aDestination,
                          nsCOMPtr<nsIAsyncInputStream>&& aStream)
      : mDestination(aDestination),
        mStream(std::move(aStream)),
        mMutex("IPCStreamDestination::DelayedStartInputStream::mMutex") {
    MOZ_ASSERT(mDestination);
    MOZ_ASSERT(mStream);
  }

  void DestinationShutdown() {
    MutexAutoLock lock(mMutex);
    mDestination = nullptr;
  }

  // nsIInputStream interface

  NS_IMETHOD
  Close() override {
    MaybeCloseDestination();
    return mStream->Close();
  }

  NS_IMETHOD
  Available(uint64_t* aLength) override {
    MaybeStartReading();
    return mStream->Available(aLength);
  }

  NS_IMETHOD
  Read(char* aBuffer, uint32_t aCount, uint32_t* aReadCount) override {
    MaybeStartReading();
    return mStream->Read(aBuffer, aCount, aReadCount);
  }

  NS_IMETHOD
  ReadSegments(nsWriteSegmentFun aWriter, void* aClosure, uint32_t aCount,
               uint32_t* aResult) override {
    MaybeStartReading();
    return mStream->ReadSegments(aWriter, aClosure, aCount, aResult);
  }

  NS_IMETHOD
  IsNonBlocking(bool* aNonBlocking) override {
    MaybeStartReading();
    return mStream->IsNonBlocking(aNonBlocking);
  }

  // nsIAsyncInputStream interface

  NS_IMETHOD
  CloseWithStatus(nsresult aReason) override {
    MaybeCloseDestination();
    return mStream->CloseWithStatus(aReason);
  }

  NS_IMETHOD
  AsyncWait(nsIInputStreamCallback* aCallback, uint32_t aFlags,
            uint32_t aRequestedCount, nsIEventTarget* aTarget) override {
    {
      MutexAutoLock lock(mMutex);
      if (mAsyncWaitCallback && aCallback) {
        return NS_ERROR_FAILURE;
      }

      mAsyncWaitCallback = aCallback;

      MaybeStartReading(lock);
    }

    nsCOMPtr<nsIInputStreamCallback> callback = aCallback ? this : nullptr;
    return mStream->AsyncWait(callback, aFlags, aRequestedCount, aTarget);
  }

  NS_IMETHOD
  Search(const char* aForString, bool aIgnoreCase, bool* aFound,
         uint32_t* aOffsetSearchedTo) override {
    MaybeStartReading();
    nsCOMPtr<nsISearchableInputStream> searchable = do_QueryInterface(mStream);
    MOZ_ASSERT(searchable);
    return searchable->Search(aForString, aIgnoreCase, aFound,
                              aOffsetSearchedTo);
  }

  // nsICloneableInputStream interface

  NS_IMETHOD
  GetCloneable(bool* aCloneable) override {
    MaybeStartReading();
    nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(mStream);
    MOZ_ASSERT(cloneable);
    return cloneable->GetCloneable(aCloneable);
  }

  NS_IMETHOD
  Clone(nsIInputStream** aResult) override {
    MaybeStartReading();
    nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(mStream);
    MOZ_ASSERT(cloneable);
    return cloneable->Clone(aResult);
  }

  // nsIBufferedInputStream

  NS_IMETHOD
  Init(nsIInputStream* aStream, uint32_t aBufferSize) override {
    MaybeStartReading();
    nsCOMPtr<nsIBufferedInputStream> stream = do_QueryInterface(mStream);
    MOZ_ASSERT(stream);
    return stream->Init(aStream, aBufferSize);
  }

  NS_IMETHODIMP
  GetData(nsIInputStream** aResult) override {
    return NS_ERROR_NOT_IMPLEMENTED;
  }

  // nsIInputStreamCallback

  NS_IMETHOD
  OnInputStreamReady(nsIAsyncInputStream* aStream) override {
    nsCOMPtr<nsIInputStreamCallback> callback;

    {
      MutexAutoLock lock(mMutex);

      // We have been canceled in the meanwhile.
      if (!mAsyncWaitCallback) {
        return NS_OK;
      }

      callback.swap(mAsyncWaitCallback);
    }

    callback->OnInputStreamReady(this);
    return NS_OK;
  }

  void MaybeStartReading();
  void MaybeStartReading(const MutexAutoLock& aProofOfLook);

  void MaybeCloseDestination();

 private:
  ~DelayedStartInputStream() = default;

  IPCStreamDestination* mDestination;
  nsCOMPtr<nsIAsyncInputStream> mStream;

  nsCOMPtr<nsIInputStreamCallback> mAsyncWaitCallback;

  // This protects mDestination: any method can be called by any thread.
  Mutex mMutex;

  class HelperRunnable;
};

class IPCStreamDestination::DelayedStartInputStream::HelperRunnable final
    : public Runnable {
 public:
  enum Op {
    eStartReading,
    eCloseDestination,
  };

  HelperRunnable(
      IPCStreamDestination::DelayedStartInputStream* aDelayedStartInputStream,
      Op aOp)
      : Runnable(
            "ipc::IPCStreamDestination::DelayedStartInputStream::"
            "HelperRunnable"),
        mDelayedStartInputStream(aDelayedStartInputStream),
        mOp(aOp) {
    MOZ_ASSERT(aDelayedStartInputStream);
  }

  NS_IMETHOD
  Run() override {
    switch (mOp) {
      case eStartReading:
        mDelayedStartInputStream->MaybeStartReading();
        break;
      case eCloseDestination:
        mDelayedStartInputStream->MaybeCloseDestination();
        break;
    }

    return NS_OK;
  }

 private:
  RefPtr<IPCStreamDestination::DelayedStartInputStream>
      mDelayedStartInputStream;
  Op mOp;
};

void IPCStreamDestination::DelayedStartInputStream::MaybeStartReading() {
  MutexAutoLock lock(mMutex);
  MaybeStartReading(lock);
}

void IPCStreamDestination::DelayedStartInputStream::MaybeStartReading(
    const MutexAutoLock& aProofOfLook) {
  if (!mDestination) {
    return;
  }

  if (mDestination->IsOnOwningThread()) {
    mDestination->StartReading();
    mDestination = nullptr;
    return;
  }

  RefPtr<Runnable> runnable =
      new HelperRunnable(this, HelperRunnable::eStartReading);
  mDestination->DispatchRunnable(runnable.forget());
}

void IPCStreamDestination::DelayedStartInputStream::MaybeCloseDestination() {
  MutexAutoLock lock(mMutex);
  if (!mDestination) {
    return;
  }

  if (mDestination->IsOnOwningThread()) {
    mDestination->RequestClose(NS_ERROR_ABORT);
    mDestination = nullptr;
    return;
  }

  RefPtr<Runnable> runnable =
      new HelperRunnable(this, HelperRunnable::eCloseDestination);
  mDestination->DispatchRunnable(runnable.forget());
}

NS_IMPL_ADDREF(IPCStreamDestination::DelayedStartInputStream);
NS_IMPL_RELEASE(IPCStreamDestination::DelayedStartInputStream);

NS_INTERFACE_MAP_BEGIN(IPCStreamDestination::DelayedStartInputStream)
  NS_INTERFACE_MAP_ENTRY(nsIAsyncInputStream)
  NS_INTERFACE_MAP_ENTRY(nsIInputStreamCallback)
  NS_INTERFACE_MAP_ENTRY(nsISearchableInputStream)
  NS_INTERFACE_MAP_ENTRY(nsICloneableInputStream)
  NS_INTERFACE_MAP_ENTRY(nsIBufferedInputStream)
  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsIInputStream, nsIAsyncInputStream)
  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIAsyncInputStream)
NS_INTERFACE_MAP_END

// ----------------------------------------------------------------------------
// IPCStreamDestination

IPCStreamDestination::IPCStreamDestination()
    : mOwningThread(NS_GetCurrentThread()),
      mDelayedStart(false)
#ifdef MOZ_DEBUG
      ,
      mLengthSet(false)
#endif
{
}

IPCStreamDestination::~IPCStreamDestination() = default;

nsresult IPCStreamDestination::Initialize() {
  MOZ_ASSERT(!mReader);
  MOZ_ASSERT(!mWriter);

  // use async versions for both reader and writer even though we are
  // opening the writer as an infinite stream.  We want to be able to
  // use CloseWithStatus() to communicate errors through the pipe.

  // Use an "infinite" pipe because we cannot apply back-pressure through
  // the async IPC layer at the moment.  Blocking the IPC worker thread
  // is not desirable, either.
  nsresult rv = NS_NewPipe2(getter_AddRefs(mReader), getter_AddRefs(mWriter),
                            true, true,   // non-blocking
                            0,            // segment size
                            UINT32_MAX);  // "infinite" pipe
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  return NS_OK;
}

void IPCStreamDestination::SetDelayedStart(bool aDelayedStart) {
  mDelayedStart = aDelayedStart;
}

void IPCStreamDestination::SetLength(int64_t aLength) {
  MOZ_ASSERT(mReader);
  MOZ_ASSERT(!mLengthSet);

#ifdef DEBUG
  mLengthSet = true;
#endif

  mLength = aLength;
}

already_AddRefed<nsIInputStream> IPCStreamDestination::TakeReader() {
  MOZ_ASSERT(mReader);
  MOZ_ASSERT(!mDelayedStartInputStream);

  nsCOMPtr<nsIAsyncInputStream> reader{mReader.forget()};
  if (mDelayedStart) {
    mDelayedStartInputStream =
        new DelayedStartInputStream(this, std::move(reader));
    reader = mDelayedStartInputStream;
    MOZ_ASSERT(reader);
  }

  if (mLength != -1) {
    MOZ_ASSERT(mLengthSet);
    nsCOMPtr<nsIInputStream> finalStream =
        new InputStreamLengthWrapper(reader.forget(), mLength);
    reader = do_QueryInterface(finalStream);
    MOZ_ASSERT(reader);
  }

  return reader.forget();
}

bool IPCStreamDestination::IsOnOwningThread() const {
  return mOwningThread == NS_GetCurrentThread();
}

void IPCStreamDestination::DispatchRunnable(
    already_AddRefed<nsIRunnable>&& aRunnable) {
  nsCOMPtr<nsIRunnable> runnable = aRunnable;
  mOwningThread->Dispatch(runnable.forget(), NS_DISPATCH_NORMAL);
}

void IPCStreamDestination::ActorDestroyed() {
  MOZ_ASSERT(mWriter);

  // If we were gracefully closed we should have gotten RecvClose().  In
  // that case, the writer will already be closed and this will have no
  // effect.  This just aborts the writer in the case where the child process
  // crashes.
  mWriter->CloseWithStatus(NS_ERROR_ABORT);

  if (mDelayedStartInputStream) {
    mDelayedStartInputStream->DestinationShutdown();
    mDelayedStartInputStream = nullptr;
  }
}

void IPCStreamDestination::BufferReceived(const wr::ByteBuffer& aBuffer) {
  MOZ_ASSERT(mWriter);

  uint32_t numWritten = 0;

  // This should only fail if we hit an OOM condition.
  nsresult rv = mWriter->Write(reinterpret_cast<char*>(aBuffer.mData),
                               aBuffer.mLength, &numWritten);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    RequestClose(rv);
  }
}

void IPCStreamDestination::CloseReceived(nsresult aRv) {
  MOZ_ASSERT(mWriter);
  mWriter->CloseWithStatus(aRv);
  TerminateDestination();
}

}  // namespace ipc
}  // namespace mozilla