gecko-dev/netwerk/base/nsSyncStreamListener.cpp

/* 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/SpinEventLoopUntil.h"
#include "nsIOService.h"
#include "nsIPipe.h"
#include "nsSyncStreamListener.h"
#include "nsThreadUtils.h"
#include <algorithm>

using namespace mozilla::net;

nsresult nsSyncStreamListener::Init() {
  return NS_NewPipe(getter_AddRefs(mPipeIn), getter_AddRefs(mPipeOut),
                    mozilla::net::nsIOService::gDefaultSegmentSize,
                    UINT32_MAX,  // no size limit
                    false, false);
}

// static
already_AddRefed<nsISyncStreamListener> nsSyncStreamListener::Create() {
  MOZ_ASSERT(NS_IsMainThread());

  RefPtr<nsSyncStreamListener> inst = new nsSyncStreamListener();
  nsresult rv = inst->Init();
  NS_ENSURE_SUCCESS(rv, nullptr);

  return inst.forget();
}

nsresult nsSyncStreamListener::WaitForData() {
  mKeepWaiting = true;

  if (!mozilla::SpinEventLoopUntil("nsSyncStreamListener::Create"_ns,
                                   [&]() { return !mKeepWaiting; })) {
    return NS_ERROR_FAILURE;
  }

  return NS_OK;
}

//-----------------------------------------------------------------------------
// nsSyncStreamListener::nsISupports
//-----------------------------------------------------------------------------

NS_IMPL_ISUPPORTS(nsSyncStreamListener, nsIStreamListener, nsIRequestObserver,
                  nsIInputStream, nsISyncStreamListener)

//-----------------------------------------------------------------------------
// nsSyncStreamListener::nsISyncStreamListener
//-----------------------------------------------------------------------------

NS_IMETHODIMP
nsSyncStreamListener::GetInputStream(nsIInputStream** result) {
  *result = do_AddRef(this).take();
  return NS_OK;
}

//-----------------------------------------------------------------------------
// nsSyncStreamListener::nsIStreamListener
//-----------------------------------------------------------------------------

NS_IMETHODIMP
nsSyncStreamListener::OnStartRequest(nsIRequest* request) { return NS_OK; }

NS_IMETHODIMP
nsSyncStreamListener::OnDataAvailable(nsIRequest* request,
                                      nsIInputStream* stream, uint64_t offset,
                                      uint32_t count) {
  uint32_t bytesWritten;

  nsresult rv = mPipeOut->WriteFrom(stream, count, &bytesWritten);

  // if we get an error, then return failure.  this will cause the
  // channel to be canceled, and as a result our OnStopRequest method
  // will be called immediately.  because of this we do not need to
  // set mStatus or mKeepWaiting here.
  if (NS_FAILED(rv)) return rv;

  // we expect that all data will be written to the pipe because
  // the pipe was created to have "infinite" room.
  NS_ASSERTION(bytesWritten == count, "did not write all data");

  mKeepWaiting = false;  // unblock Read
  return NS_OK;
}

NS_IMETHODIMP
nsSyncStreamListener::OnStopRequest(nsIRequest* request, nsresult status) {
  mStatus = status;
  mKeepWaiting = false;  // unblock Read
  mDone = true;
  return NS_OK;
}

//-----------------------------------------------------------------------------
// nsSyncStreamListener::nsIInputStream
//-----------------------------------------------------------------------------

NS_IMETHODIMP
nsSyncStreamListener::Close() {
  mStatus = NS_BASE_STREAM_CLOSED;
  mDone = true;

  // It'd be nice if we could explicitly cancel the request at this point,
  // but we don't have a reference to it, so the best we can do is close the
  // pipe so that the next OnDataAvailable event will fail.
  if (mPipeIn) {
    mPipeIn->Close();
    mPipeIn = nullptr;
  }
  return NS_OK;
}

NS_IMETHODIMP
nsSyncStreamListener::Available(uint64_t* result) {
  if (NS_FAILED(mStatus)) return mStatus;

  mStatus = mPipeIn->Available(result);
  if (NS_SUCCEEDED(mStatus) && (*result == 0) && !mDone) {
    nsresult rv = WaitForData();
    if (NS_FAILED(rv)) {
      // Note that `WaitForData` could fail `mStatus`. Do not overwrite if it's
      // the case.
      mStatus = NS_SUCCEEDED(mStatus) ? rv : mStatus;
    } else if (NS_SUCCEEDED(mStatus)) {
      mStatus = mPipeIn->Available(result);
    }
  }
  return mStatus;
}

NS_IMETHODIMP
nsSyncStreamListener::Read(char* buf, uint32_t bufLen, uint32_t* result) {
  if (mStatus == NS_BASE_STREAM_CLOSED) {
    *result = 0;
    return NS_OK;
  }

  uint64_t avail64;
  if (NS_FAILED(Available(&avail64))) return mStatus;

  uint32_t avail = (uint32_t)std::min(avail64, (uint64_t)bufLen);
  mStatus = mPipeIn->Read(buf, avail, result);
  return mStatus;
}

NS_IMETHODIMP
nsSyncStreamListener::ReadSegments(nsWriteSegmentFun writer, void* closure,
                                   uint32_t count, uint32_t* result) {
  if (mStatus == NS_BASE_STREAM_CLOSED) {
    *result = 0;
    return NS_OK;
  }

  uint64_t avail64;
  if (NS_FAILED(Available(&avail64))) return mStatus;

  uint32_t avail = (uint32_t)std::min(avail64, (uint64_t)count);
  mStatus = mPipeIn->ReadSegments(writer, closure, avail, result);
  return mStatus;
}

NS_IMETHODIMP
nsSyncStreamListener::IsNonBlocking(bool* result) {
  *result = false;
  return NS_OK;
}