gecko-dev/xpcom/io/nsStreamUtils.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 "mozilla/Mutex.h"
#include "mozilla/Attributes.h"
#include "nsStreamUtils.h"
#include "nsAutoPtr.h"
#include "nsCOMPtr.h"
#include "nsIPipe.h"
#include "nsICloneableInputStream.h"
#include "nsIEventTarget.h"
#include "nsICancelableRunnable.h"
#include "nsISafeOutputStream.h"
#include "nsString.h"
#include "nsIAsyncInputStream.h"
#include "nsIAsyncOutputStream.h"
#include "nsIBufferedStreams.h"
#include "nsNetCID.h"
#include "nsServiceManagerUtils.h"
#include "nsThreadUtils.h"
#include "nsITransport.h"
#include "nsIStreamTransportService.h"
#include "NonBlockingAsyncInputStream.h"

using namespace mozilla;

static NS_DEFINE_CID(kStreamTransportServiceCID, NS_STREAMTRANSPORTSERVICE_CID);

//-----------------------------------------------------------------------------

// This is a nsICancelableRunnable because we can dispatch it to Workers and
// those can be shut down at any time, and in these cases, Cancel() is called
// instead of Run().
class nsInputStreamReadyEvent final : public CancelableRunnable,
                                      public nsIInputStreamCallback {
 public:
  NS_DECL_ISUPPORTS_INHERITED

  nsInputStreamReadyEvent(const char* aName, nsIInputStreamCallback* aCallback,
                          nsIEventTarget* aTarget)
      : CancelableRunnable(aName), mCallback(aCallback), mTarget(aTarget) {}

 private:
  ~nsInputStreamReadyEvent() {
    if (!mCallback) {
      return;
    }
    //
    // whoa!!  looks like we never posted this event.  take care to
    // release mCallback on the correct thread.  if mTarget lives on the
    // calling thread, then we are ok.  otherwise, we have to try to
    // proxy the Release over the right thread.  if that thread is dead,
    // then there's nothing we can do... better to leak than crash.
    //
    bool val;
    nsresult rv = mTarget->IsOnCurrentThread(&val);
    if (NS_FAILED(rv) || !val) {
      nsCOMPtr<nsIInputStreamCallback> event = NS_NewInputStreamReadyEvent(
          "~nsInputStreamReadyEvent", mCallback, mTarget);
      mCallback = nullptr;
      if (event) {
        rv = event->OnInputStreamReady(nullptr);
        if (NS_FAILED(rv)) {
          MOZ_ASSERT_UNREACHABLE("leaking stream event");
          nsISupports* sup = event;
          NS_ADDREF(sup);
        }
      }
    }
  }

 public:
  NS_IMETHOD OnInputStreamReady(nsIAsyncInputStream* aStream) override {
    mStream = aStream;

    nsresult rv = mTarget->Dispatch(this, NS_DISPATCH_NORMAL);
    if (NS_FAILED(rv)) {
      NS_WARNING("Dispatch failed");
      return NS_ERROR_FAILURE;
    }

    return NS_OK;
  }

  NS_IMETHOD Run() override {
    if (mCallback) {
      if (mStream) {
        mCallback->OnInputStreamReady(mStream);
      }
      mCallback = nullptr;
    }
    return NS_OK;
  }

  nsresult Cancel() override {
    mCallback = nullptr;
    return NS_OK;
  }

 private:
  nsCOMPtr<nsIAsyncInputStream> mStream;
  nsCOMPtr<nsIInputStreamCallback> mCallback;
  nsCOMPtr<nsIEventTarget> mTarget;
};

NS_IMPL_ISUPPORTS_INHERITED(nsInputStreamReadyEvent, CancelableRunnable,
                            nsIInputStreamCallback)

//-----------------------------------------------------------------------------

// This is a nsICancelableRunnable because we can dispatch it to Workers and
// those can be shut down at any time, and in these cases, Cancel() is called
// instead of Run().
class nsOutputStreamReadyEvent final : public CancelableRunnable,
                                       public nsIOutputStreamCallback {
 public:
  NS_DECL_ISUPPORTS_INHERITED

  nsOutputStreamReadyEvent(nsIOutputStreamCallback* aCallback,
                           nsIEventTarget* aTarget)
      : CancelableRunnable("nsOutputStreamReadyEvent"),
        mCallback(aCallback),
        mTarget(aTarget) {}

 private:
  ~nsOutputStreamReadyEvent() {
    if (!mCallback) {
      return;
    }
    //
    // whoa!!  looks like we never posted this event.  take care to
    // release mCallback on the correct thread.  if mTarget lives on the
    // calling thread, then we are ok.  otherwise, we have to try to
    // proxy the Release over the right thread.  if that thread is dead,
    // then there's nothing we can do... better to leak than crash.
    //
    bool val;
    nsresult rv = mTarget->IsOnCurrentThread(&val);
    if (NS_FAILED(rv) || !val) {
      nsCOMPtr<nsIOutputStreamCallback> event =
          NS_NewOutputStreamReadyEvent(mCallback, mTarget);
      mCallback = nullptr;
      if (event) {
        rv = event->OnOutputStreamReady(nullptr);
        if (NS_FAILED(rv)) {
          MOZ_ASSERT_UNREACHABLE("leaking stream event");
          nsISupports* sup = event;
          NS_ADDREF(sup);
        }
      }
    }
  }

 public:
  NS_IMETHOD OnOutputStreamReady(nsIAsyncOutputStream* aStream) override {
    mStream = aStream;

    nsresult rv = mTarget->Dispatch(this, NS_DISPATCH_NORMAL);
    if (NS_FAILED(rv)) {
      NS_WARNING("PostEvent failed");
      return NS_ERROR_FAILURE;
    }

    return NS_OK;
  }

  NS_IMETHOD Run() override {
    if (mCallback) {
      if (mStream) {
        mCallback->OnOutputStreamReady(mStream);
      }
      mCallback = nullptr;
    }
    return NS_OK;
  }

  nsresult Cancel() override {
    mCallback = nullptr;
    return NS_OK;
  }

 private:
  nsCOMPtr<nsIAsyncOutputStream> mStream;
  nsCOMPtr<nsIOutputStreamCallback> mCallback;
  nsCOMPtr<nsIEventTarget> mTarget;
};

NS_IMPL_ISUPPORTS_INHERITED(nsOutputStreamReadyEvent, CancelableRunnable,
                            nsIOutputStreamCallback)

//-----------------------------------------------------------------------------

already_AddRefed<nsIInputStreamCallback> NS_NewInputStreamReadyEvent(
    const char* aName, nsIInputStreamCallback* aCallback,
    nsIEventTarget* aTarget) {
  NS_ASSERTION(aCallback, "null callback");
  NS_ASSERTION(aTarget, "null target");
  RefPtr<nsInputStreamReadyEvent> ev =
      new nsInputStreamReadyEvent(aName, aCallback, aTarget);
  return ev.forget();
}

already_AddRefed<nsIOutputStreamCallback> NS_NewOutputStreamReadyEvent(
    nsIOutputStreamCallback* aCallback, nsIEventTarget* aTarget) {
  NS_ASSERTION(aCallback, "null callback");
  NS_ASSERTION(aTarget, "null target");
  RefPtr<nsOutputStreamReadyEvent> ev =
      new nsOutputStreamReadyEvent(aCallback, aTarget);
  return ev.forget();
}

//-----------------------------------------------------------------------------
// NS_AsyncCopy implementation

// abstract stream copier...
class nsAStreamCopier : public nsIInputStreamCallback,
                        public nsIOutputStreamCallback,
                        public CancelableRunnable {
 public:
  NS_DECL_ISUPPORTS_INHERITED

  nsAStreamCopier()
      : CancelableRunnable("nsAStreamCopier"),
        mLock("nsAStreamCopier.mLock"),
        mCallback(nullptr),
        mProgressCallback(nullptr),
        mClosure(nullptr),
        mChunkSize(0),
        mEventInProcess(false),
        mEventIsPending(false),
        mCloseSource(true),
        mCloseSink(true),
        mCanceled(false),
        mCancelStatus(NS_OK) {}

  // kick off the async copy...
  nsresult Start(nsIInputStream* aSource, nsIOutputStream* aSink,
                 nsIEventTarget* aTarget, nsAsyncCopyCallbackFun aCallback,
                 void* aClosure, uint32_t aChunksize, bool aCloseSource,
                 bool aCloseSink, nsAsyncCopyProgressFun aProgressCallback) {
    mSource = aSource;
    mSink = aSink;
    mTarget = aTarget;
    mCallback = aCallback;
    mClosure = aClosure;
    mChunkSize = aChunksize;
    mCloseSource = aCloseSource;
    mCloseSink = aCloseSink;
    mProgressCallback = aProgressCallback;

    mAsyncSource = do_QueryInterface(mSource);
    mAsyncSink = do_QueryInterface(mSink);

    return PostContinuationEvent();
  }

  // implemented by subclasses, returns number of bytes copied and
  // sets source and sink condition before returning.
  virtual uint32_t DoCopy(nsresult* aSourceCondition,
                          nsresult* aSinkCondition) = 0;

  void Process() {
    if (!mSource || !mSink) {
      return;
    }

    nsresult cancelStatus;
    bool canceled;
    {
      MutexAutoLock lock(mLock);
      canceled = mCanceled;
      cancelStatus = mCancelStatus;
    }

    // If the copy was canceled before Process() was even called, then
    // sourceCondition and sinkCondition should be set to error results to
    // ensure we don't call Finish() on a canceled nsISafeOutputStream.
    MOZ_ASSERT(NS_FAILED(cancelStatus) == canceled, "cancel needs an error");
    nsresult sourceCondition = cancelStatus;
    nsresult sinkCondition = cancelStatus;

    // Copy data from the source to the sink until we hit failure or have
    // copied all the data.
    for (;;) {
      // Note: copyFailed will be true if the source or the sink have
      //       reported an error, or if we failed to write any bytes
      //       because we have consumed all of our data.
      bool copyFailed = false;
      if (!canceled) {
        uint32_t n = DoCopy(&sourceCondition, &sinkCondition);
        if (n > 0 && mProgressCallback) {
          mProgressCallback(mClosure, n);
        }
        copyFailed =
            NS_FAILED(sourceCondition) || NS_FAILED(sinkCondition) || n == 0;

        MutexAutoLock lock(mLock);
        canceled = mCanceled;
        cancelStatus = mCancelStatus;
      }
      if (copyFailed && !canceled) {
        if (sourceCondition == NS_BASE_STREAM_WOULD_BLOCK && mAsyncSource) {
          // need to wait for more data from source.  while waiting for
          // more source data, be sure to observe failures on output end.
          mAsyncSource->AsyncWait(this, 0, 0, nullptr);

          if (mAsyncSink)
            mAsyncSink->AsyncWait(this, nsIAsyncOutputStream::WAIT_CLOSURE_ONLY,
                                  0, nullptr);
          break;
        } else if (sinkCondition == NS_BASE_STREAM_WOULD_BLOCK && mAsyncSink) {
          // need to wait for more room in the sink.  while waiting for
          // more room in the sink, be sure to observer failures on the
          // input end.
          mAsyncSink->AsyncWait(this, 0, 0, nullptr);

          if (mAsyncSource)
            mAsyncSource->AsyncWait(
                this, nsIAsyncInputStream::WAIT_CLOSURE_ONLY, 0, nullptr);
          break;
        }
      }
      if (copyFailed || canceled) {
        if (mCloseSource) {
          // close source
          if (mAsyncSource)
            mAsyncSource->CloseWithStatus(canceled ? cancelStatus
                                                   : sinkCondition);
          else {
            mSource->Close();
          }
        }
        mAsyncSource = nullptr;
        mSource = nullptr;

        if (mCloseSink) {
          // close sink
          if (mAsyncSink)
            mAsyncSink->CloseWithStatus(canceled ? cancelStatus
                                                 : sourceCondition);
          else {
            // If we have an nsISafeOutputStream, and our
            // sourceCondition and sinkCondition are not set to a
            // failure state, finish writing.
            nsCOMPtr<nsISafeOutputStream> sostream = do_QueryInterface(mSink);
            if (sostream && NS_SUCCEEDED(sourceCondition) &&
                NS_SUCCEEDED(sinkCondition)) {
              sostream->Finish();
            } else {
              mSink->Close();
            }
          }
        }
        mAsyncSink = nullptr;
        mSink = nullptr;

        // notify state complete...
        if (mCallback) {
          nsresult status;
          if (!canceled) {
            status = sourceCondition;
            if (NS_SUCCEEDED(status)) {
              status = sinkCondition;
            }
            if (status == NS_BASE_STREAM_CLOSED) {
              status = NS_OK;
            }
          } else {
            status = cancelStatus;
          }
          mCallback(mClosure, status);
        }
        break;
      }
    }
  }

  nsresult Cancel(nsresult aReason) {
    MutexAutoLock lock(mLock);
    if (mCanceled) {
      return NS_ERROR_FAILURE;
    }

    if (NS_SUCCEEDED(aReason)) {
      NS_WARNING("cancel with non-failure status code");
      aReason = NS_BASE_STREAM_CLOSED;
    }

    mCanceled = true;
    mCancelStatus = aReason;
    return NS_OK;
  }

  NS_IMETHOD OnInputStreamReady(nsIAsyncInputStream* aSource) override {
    PostContinuationEvent();
    return NS_OK;
  }

  NS_IMETHOD OnOutputStreamReady(nsIAsyncOutputStream* aSink) override {
    PostContinuationEvent();
    return NS_OK;
  }

  // continuation event handler
  NS_IMETHOD Run() override {
    Process();

    // clear "in process" flag and post any pending continuation event
    MutexAutoLock lock(mLock);
    mEventInProcess = false;
    if (mEventIsPending) {
      mEventIsPending = false;
      PostContinuationEvent_Locked();
    }

    return NS_OK;
  }

  nsresult Cancel() MOZ_MUST_OVERRIDE override = 0;

  nsresult PostContinuationEvent() {
    // we cannot post a continuation event if there is currently
    // an event in process.  doing so could result in Process being
    // run simultaneously on multiple threads, so we mark the event
    // as pending, and if an event is already in process then we
    // just let that existing event take care of posting the real
    // continuation event.

    MutexAutoLock lock(mLock);
    return PostContinuationEvent_Locked();
  }

  nsresult PostContinuationEvent_Locked() {
    nsresult rv = NS_OK;
    if (mEventInProcess) {
      mEventIsPending = true;
    } else {
      rv = mTarget->Dispatch(this, NS_DISPATCH_NORMAL);
      if (NS_SUCCEEDED(rv)) {
        mEventInProcess = true;
      } else {
        NS_WARNING("unable to post continuation event");
      }
    }
    return rv;
  }

 protected:
  nsCOMPtr<nsIInputStream> mSource;
  nsCOMPtr<nsIOutputStream> mSink;
  nsCOMPtr<nsIAsyncInputStream> mAsyncSource;
  nsCOMPtr<nsIAsyncOutputStream> mAsyncSink;
  nsCOMPtr<nsIEventTarget> mTarget;
  Mutex mLock;
  nsAsyncCopyCallbackFun mCallback;
  nsAsyncCopyProgressFun mProgressCallback;
  void* mClosure;
  uint32_t mChunkSize;
  bool mEventInProcess;
  bool mEventIsPending;
  bool mCloseSource;
  bool mCloseSink;
  bool mCanceled;
  nsresult mCancelStatus;

  // virtual since subclasses call superclass Release()
  virtual ~nsAStreamCopier() {}
};

NS_IMPL_ISUPPORTS_INHERITED(nsAStreamCopier, CancelableRunnable,
                            nsIInputStreamCallback, nsIOutputStreamCallback)

class nsStreamCopierIB final : public nsAStreamCopier {
 public:
  nsStreamCopierIB() : nsAStreamCopier() {}
  virtual ~nsStreamCopierIB() {}

  struct MOZ_STACK_CLASS ReadSegmentsState {
    // the nsIOutputStream will outlive the ReadSegmentsState on the stack
    nsIOutputStream* MOZ_NON_OWNING_REF mSink;
    nsresult mSinkCondition;
  };

  static nsresult ConsumeInputBuffer(nsIInputStream* aInStr, void* aClosure,
                                     const char* aBuffer, uint32_t aOffset,
                                     uint32_t aCount, uint32_t* aCountWritten) {
    ReadSegmentsState* state = (ReadSegmentsState*)aClosure;

    nsresult rv = state->mSink->Write(aBuffer, aCount, aCountWritten);
    if (NS_FAILED(rv)) {
      state->mSinkCondition = rv;
    } else if (*aCountWritten == 0) {
      state->mSinkCondition = NS_BASE_STREAM_CLOSED;
    }

    return state->mSinkCondition;
  }

  uint32_t DoCopy(nsresult* aSourceCondition,
                  nsresult* aSinkCondition) override {
    ReadSegmentsState state;
    state.mSink = mSink;
    state.mSinkCondition = NS_OK;

    uint32_t n;
    *aSourceCondition =
        mSource->ReadSegments(ConsumeInputBuffer, &state, mChunkSize, &n);
    *aSinkCondition = state.mSinkCondition;
    return n;
  }

  nsresult Cancel() override { return NS_OK; }
};

class nsStreamCopierOB final : public nsAStreamCopier {
 public:
  nsStreamCopierOB() : nsAStreamCopier() {}
  virtual ~nsStreamCopierOB() {}

  struct MOZ_STACK_CLASS WriteSegmentsState {
    // the nsIInputStream will outlive the WriteSegmentsState on the stack
    nsIInputStream* MOZ_NON_OWNING_REF mSource;
    nsresult mSourceCondition;
  };

  static nsresult FillOutputBuffer(nsIOutputStream* aOutStr, void* aClosure,
                                   char* aBuffer, uint32_t aOffset,
                                   uint32_t aCount, uint32_t* aCountRead) {
    WriteSegmentsState* state = (WriteSegmentsState*)aClosure;

    nsresult rv = state->mSource->Read(aBuffer, aCount, aCountRead);
    if (NS_FAILED(rv)) {
      state->mSourceCondition = rv;
    } else if (*aCountRead == 0) {
      state->mSourceCondition = NS_BASE_STREAM_CLOSED;
    }

    return state->mSourceCondition;
  }

  uint32_t DoCopy(nsresult* aSourceCondition,
                  nsresult* aSinkCondition) override {
    WriteSegmentsState state;
    state.mSource = mSource;
    state.mSourceCondition = NS_OK;

    uint32_t n;
    *aSinkCondition =
        mSink->WriteSegments(FillOutputBuffer, &state, mChunkSize, &n);
    *aSourceCondition = state.mSourceCondition;
    return n;
  }

  nsresult Cancel() override { return NS_OK; }
};

//-----------------------------------------------------------------------------

nsresult NS_AsyncCopy(nsIInputStream* aSource, nsIOutputStream* aSink,
                      nsIEventTarget* aTarget, nsAsyncCopyMode aMode,
                      uint32_t aChunkSize, nsAsyncCopyCallbackFun aCallback,
                      void* aClosure, bool aCloseSource, bool aCloseSink,
                      nsISupports** aCopierCtx,
                      nsAsyncCopyProgressFun aProgressCallback) {
  NS_ASSERTION(aTarget, "non-null target required");

  nsresult rv;
  nsAStreamCopier* copier;

  if (aMode == NS_ASYNCCOPY_VIA_READSEGMENTS) {
    copier = new nsStreamCopierIB();
  } else {
    copier = new nsStreamCopierOB();
  }

  // Start() takes an owning ref to the copier...
  NS_ADDREF(copier);
  rv = copier->Start(aSource, aSink, aTarget, aCallback, aClosure, aChunkSize,
                     aCloseSource, aCloseSink, aProgressCallback);

  if (aCopierCtx) {
    *aCopierCtx = static_cast<nsISupports*>(static_cast<nsIRunnable*>(copier));
    NS_ADDREF(*aCopierCtx);
  }
  NS_RELEASE(copier);

  return rv;
}

//-----------------------------------------------------------------------------

nsresult NS_CancelAsyncCopy(nsISupports* aCopierCtx, nsresult aReason) {
  nsAStreamCopier* copier =
      static_cast<nsAStreamCopier*>(static_cast<nsIRunnable*>(aCopierCtx));
  return copier->Cancel(aReason);
}

//-----------------------------------------------------------------------------

nsresult NS_ConsumeStream(nsIInputStream* aStream, uint32_t aMaxCount,
                          nsACString& aResult) {
  nsresult rv = NS_OK;
  aResult.Truncate();

  while (aMaxCount) {
    uint64_t avail64;
    rv = aStream->Available(&avail64);
    if (NS_FAILED(rv)) {
      if (rv == NS_BASE_STREAM_CLOSED) {
        rv = NS_OK;
      }
      break;
    }
    if (avail64 == 0) {
      break;
    }

    uint32_t avail = (uint32_t)XPCOM_MIN<uint64_t>(avail64, aMaxCount);

    // resize aResult buffer
    uint32_t length = aResult.Length();
    if (avail > UINT32_MAX - length) {
      return NS_ERROR_FILE_TOO_BIG;
    }

    aResult.SetLength(length + avail);
    if (aResult.Length() != (length + avail)) {
      return NS_ERROR_OUT_OF_MEMORY;
    }
    char* buf = aResult.BeginWriting() + length;

    uint32_t n;
    rv = aStream->Read(buf, avail, &n);
    if (NS_FAILED(rv)) {
      break;
    }
    if (n != avail) {
      aResult.SetLength(length + n);
    }
    if (n == 0) {
      break;
    }
    aMaxCount -= n;
  }

  return rv;
}

//-----------------------------------------------------------------------------

static nsresult TestInputStream(nsIInputStream* aInStr, void* aClosure,
                                const char* aBuffer, uint32_t aOffset,
                                uint32_t aCount, uint32_t* aCountWritten) {
  bool* result = static_cast<bool*>(aClosure);
  *result = true;
  *aCountWritten = 0;
  return NS_ERROR_ABORT;  // don't call me anymore
}

bool NS_InputStreamIsBuffered(nsIInputStream* aStream) {
  nsCOMPtr<nsIBufferedInputStream> bufferedIn = do_QueryInterface(aStream);
  if (bufferedIn) {
    return true;
  }

  bool result = false;
  uint32_t n;
  nsresult rv = aStream->ReadSegments(TestInputStream, &result, 1, &n);
  return result || NS_SUCCEEDED(rv);
}

static nsresult TestOutputStream(nsIOutputStream* aOutStr, void* aClosure,
                                 char* aBuffer, uint32_t aOffset,
                                 uint32_t aCount, uint32_t* aCountRead) {
  bool* result = static_cast<bool*>(aClosure);
  *result = true;
  *aCountRead = 0;
  return NS_ERROR_ABORT;  // don't call me anymore
}

bool NS_OutputStreamIsBuffered(nsIOutputStream* aStream) {
  nsCOMPtr<nsIBufferedOutputStream> bufferedOut = do_QueryInterface(aStream);
  if (bufferedOut) {
    return true;
  }

  bool result = false;
  uint32_t n;
  aStream->WriteSegments(TestOutputStream, &result, 1, &n);
  return result;
}

//-----------------------------------------------------------------------------

nsresult NS_CopySegmentToStream(nsIInputStream* aInStr, void* aClosure,
                                const char* aBuffer, uint32_t aOffset,
                                uint32_t aCount, uint32_t* aCountWritten) {
  nsIOutputStream* outStr = static_cast<nsIOutputStream*>(aClosure);
  *aCountWritten = 0;
  while (aCount) {
    uint32_t n;
    nsresult rv = outStr->Write(aBuffer, aCount, &n);
    if (NS_FAILED(rv)) {
      return rv;
    }
    aBuffer += n;
    aCount -= n;
    *aCountWritten += n;
  }
  return NS_OK;
}

nsresult NS_CopySegmentToBuffer(nsIInputStream* aInStr, void* aClosure,
                                const char* aBuffer, uint32_t aOffset,
                                uint32_t aCount, uint32_t* aCountWritten) {
  char* toBuf = static_cast<char*>(aClosure);
  memcpy(&toBuf[aOffset], aBuffer, aCount);
  *aCountWritten = aCount;
  return NS_OK;
}

nsresult NS_CopySegmentToBuffer(nsIOutputStream* aOutStr, void* aClosure,
                                char* aBuffer, uint32_t aOffset,
                                uint32_t aCount, uint32_t* aCountRead) {
  const char* fromBuf = static_cast<const char*>(aClosure);
  memcpy(aBuffer, &fromBuf[aOffset], aCount);
  *aCountRead = aCount;
  return NS_OK;
}

nsresult NS_DiscardSegment(nsIInputStream* aInStr, void* aClosure,
                           const char* aBuffer, uint32_t aOffset,
                           uint32_t aCount, uint32_t* aCountWritten) {
  *aCountWritten = aCount;
  return NS_OK;
}

//-----------------------------------------------------------------------------

nsresult NS_WriteSegmentThunk(nsIInputStream* aInStr, void* aClosure,
                              const char* aBuffer, uint32_t aOffset,
                              uint32_t aCount, uint32_t* aCountWritten) {
  nsWriteSegmentThunk* thunk = static_cast<nsWriteSegmentThunk*>(aClosure);
  return thunk->mFun(thunk->mStream, thunk->mClosure, aBuffer, aOffset, aCount,
                     aCountWritten);
}

nsresult NS_FillArray(FallibleTArray<char>& aDest, nsIInputStream* aInput,
                      uint32_t aKeep, uint32_t* aNewBytes) {
  MOZ_ASSERT(aInput, "null stream");
  MOZ_ASSERT(aKeep <= aDest.Length(), "illegal keep count");

  char* aBuffer = aDest.Elements();
  int64_t keepOffset = int64_t(aDest.Length()) - aKeep;
  if (aKeep != 0 && keepOffset > 0) {
    memmove(aBuffer, aBuffer + keepOffset, aKeep);
  }

  nsresult rv =
      aInput->Read(aBuffer + aKeep, aDest.Capacity() - aKeep, aNewBytes);
  if (NS_FAILED(rv)) {
    *aNewBytes = 0;
  }
  // NOTE: we rely on the fact that the new slots are NOT initialized by
  // SetLengthAndRetainStorage here, see nsTArrayElementTraits::Construct()
  // in nsTArray.h:
  aDest.SetLengthAndRetainStorage(aKeep + *aNewBytes);

  MOZ_ASSERT(aDest.Length() <= aDest.Capacity(), "buffer overflow");
  return rv;
}

bool NS_InputStreamIsCloneable(nsIInputStream* aSource) {
  if (!aSource) {
    return false;
  }

  nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(aSource);
  return cloneable && cloneable->GetCloneable();
}

nsresult NS_CloneInputStream(nsIInputStream* aSource,
                             nsIInputStream** aCloneOut,
                             nsIInputStream** aReplacementOut) {
  if (NS_WARN_IF(!aSource)) {
    return NS_ERROR_FAILURE;
  }

  // Attempt to perform the clone directly on the source stream
  nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(aSource);
  if (cloneable && cloneable->GetCloneable()) {
    if (aReplacementOut) {
      *aReplacementOut = nullptr;
    }
    return cloneable->Clone(aCloneOut);
  }

  // If we failed the clone and the caller does not want to replace their
  // original stream, then we are done.  Return error.
  if (!aReplacementOut) {
    return NS_ERROR_FAILURE;
  }

  // The caller has opted-in to the fallback clone support that replaces
  // the original stream.  Copy the data to a pipe and return two cloned
  // input streams.

  nsCOMPtr<nsIInputStream> reader;
  nsCOMPtr<nsIInputStream> readerClone;
  nsCOMPtr<nsIOutputStream> writer;

  nsresult rv = NS_NewPipe(getter_AddRefs(reader), getter_AddRefs(writer), 0,
                           0,            // default segment size and max size
                           true, true);  // non-blocking
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  cloneable = do_QueryInterface(reader);
  MOZ_ASSERT(cloneable && cloneable->GetCloneable());

  rv = cloneable->Clone(getter_AddRefs(readerClone));
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  nsCOMPtr<nsIEventTarget> target =
      do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID, &rv);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  rv = NS_AsyncCopy(aSource, writer, target, NS_ASYNCCOPY_VIA_WRITESEGMENTS);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  readerClone.forget(aCloneOut);
  reader.forget(aReplacementOut);

  return NS_OK;
}

nsresult NS_MakeAsyncNonBlockingInputStream(
    already_AddRefed<nsIInputStream> aSource,
    nsIAsyncInputStream** aAsyncInputStream) {
  nsCOMPtr<nsIInputStream> source = std::move(aSource);
  if (NS_WARN_IF(!aAsyncInputStream)) {
    return NS_ERROR_FAILURE;
  }

  bool nonBlocking = false;
  nsresult rv = source->IsNonBlocking(&nonBlocking);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  nsCOMPtr<nsIAsyncInputStream> asyncStream = do_QueryInterface(source);

  if (nonBlocking && asyncStream) {
    // This stream is perfect!
    asyncStream.forget(aAsyncInputStream);
    return NS_OK;
  }

  if (nonBlocking) {
    // If the stream is non-blocking but not async, we wrap it.
    return NonBlockingAsyncInputStream::Create(source.forget(),
                                               aAsyncInputStream);
  }

  nsCOMPtr<nsIStreamTransportService> sts =
      do_GetService(kStreamTransportServiceCID, &rv);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  nsCOMPtr<nsITransport> transport;
  rv = sts->CreateInputTransport(source,
                                 /* aCloseWhenDone */ true,
                                 getter_AddRefs(transport));
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  nsCOMPtr<nsIInputStream> wrapper;
  rv = transport->OpenInputStream(/* aFlags */ 0,
                                  /* aSegmentSize */ 0,
                                  /* aSegmentCount */ 0,
                                  getter_AddRefs(wrapper));
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  asyncStream = do_QueryInterface(wrapper);
  MOZ_ASSERT(asyncStream);

  asyncStream.forget(aAsyncInputStream);
  return NS_OK;
}