Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 1884 insertions, 0 deletions

diff --git a/xpcom/io/nsPipe3.cpp b/xpcom/io/nsPipe3.cpp
new file mode 100644
index 0000000000..3d7486e673
--- /dev/null
+++ b/xpcom/io/nsPipe3.cpp
@@ -0,0 +1,1884 @@
+/* -*- 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 <algorithm>
+#include "mozilla/Attributes.h"
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/ReentrantMonitor.h"
+#include "nsIBufferedStreams.h"
+#include "nsICloneableInputStream.h"
+#include "nsIPipe.h"
+#include "nsIEventTarget.h"
+#include "nsITellableStream.h"
+#include "mozilla/RefPtr.h"
+#include "nsSegmentedBuffer.h"
+#include "nsStreamUtils.h"
+#include "nsString.h"
+#include "nsCOMPtr.h"
+#include "nsCRT.h"
+#include "mozilla/Logging.h"
+#include "nsIClassInfoImpl.h"
+#include "nsAlgorithm.h"
+#include "nsPipe.h"
+#include "nsIAsyncInputStream.h"
+#include "nsIAsyncOutputStream.h"
+#include "nsIInputStreamPriority.h"
+#include "nsThreadUtils.h"
+
+using namespace mozilla;
+
+#ifdef LOG
+#  undef LOG
+#endif
+//
+// set MOZ_LOG=nsPipe:5
+//
+static LazyLogModule sPipeLog("nsPipe");
+#define LOG(args) MOZ_LOG(sPipeLog, mozilla::LogLevel::Debug, args)
+
+#define DEFAULT_SEGMENT_SIZE 4096
+#define DEFAULT_SEGMENT_COUNT 16
+
+class nsPipe;
+class nsPipeEvents;
+class nsPipeInputStream;
+class nsPipeOutputStream;
+class AutoReadSegment;
+
+namespace {
+
+enum MonitorAction { DoNotNotifyMonitor, NotifyMonitor };
+
+enum SegmentChangeResult { SegmentNotChanged, SegmentAdvanceBufferRead };
+
+}  // namespace
+
+//-----------------------------------------------------------------------------
+
+class CallbackHolder {
+ public:
+  CallbackHolder() = default;
+  MOZ_IMPLICIT CallbackHolder(std::nullptr_t) {}
+
+  CallbackHolder(nsIAsyncInputStream* aStream,
+                 nsIInputStreamCallback* aCallback, uint32_t aFlags,
+                 nsIEventTarget* aEventTarget)
+      : mRunnable(aCallback ? NS_NewCancelableRunnableFunction(
+                                  "nsPipeInputStream AsyncWait Callback",
+                                  [stream = nsCOMPtr{aStream},
+                                   callback = nsCOMPtr{aCallback}]() {
+                                    callback->OnInputStreamReady(stream);
+                                  })
+                            : nullptr),
+        mEventTarget(aEventTarget),
+        mFlags(aFlags) {}
+
+  CallbackHolder(nsIAsyncOutputStream* aStream,
+                 nsIOutputStreamCallback* aCallback, uint32_t aFlags,
+                 nsIEventTarget* aEventTarget)
+      : mRunnable(aCallback ? NS_NewCancelableRunnableFunction(
+                                  "nsPipeOutputStream AsyncWait Callback",
+                                  [stream = nsCOMPtr{aStream},
+                                   callback = nsCOMPtr{aCallback}]() {
+                                    callback->OnOutputStreamReady(stream);
+                                  })
+                            : nullptr),
+        mEventTarget(aEventTarget),
+        mFlags(aFlags) {}
+
+  CallbackHolder(const CallbackHolder&) = delete;
+  CallbackHolder(CallbackHolder&&) = default;
+  CallbackHolder& operator=(const CallbackHolder&) = delete;
+  CallbackHolder& operator=(CallbackHolder&&) = default;
+
+  CallbackHolder& operator=(std::nullptr_t) {
+    mRunnable = nullptr;
+    mEventTarget = nullptr;
+    mFlags = 0;
+    return *this;
+  }
+
+  MOZ_IMPLICIT operator bool() const { return mRunnable; }
+
+  uint32_t Flags() const {
+    MOZ_ASSERT(mRunnable, "Should only be called when a callback is present");
+    return mFlags;
+  }
+
+  void Notify() {
+    nsCOMPtr<nsIRunnable> runnable = mRunnable.forget();
+    nsCOMPtr<nsIEventTarget> eventTarget = mEventTarget.forget();
+    if (runnable) {
+      if (eventTarget) {
+        eventTarget->Dispatch(runnable.forget());
+      } else {
+        runnable->Run();
+      }
+    }
+  }
+
+ private:
+  nsCOMPtr<nsIRunnable> mRunnable;
+  nsCOMPtr<nsIEventTarget> mEventTarget;
+  uint32_t mFlags = 0;
+};
+
+//-----------------------------------------------------------------------------
+
+// this class is used to delay notifications until the end of a particular
+// scope.  it helps avoid the complexity of issuing callbacks while inside
+// a critical section.
+class nsPipeEvents {
+ public:
+  nsPipeEvents() = default;
+  ~nsPipeEvents();
+
+  inline void NotifyReady(CallbackHolder aCallback) {
+    mCallbacks.AppendElement(std::move(aCallback));
+  }
+
+ private:
+  nsTArray<CallbackHolder> mCallbacks;
+};
+
+//-----------------------------------------------------------------------------
+
+// This class is used to maintain input stream state.  Its broken out from the
+// nsPipeInputStream class because generally the nsPipe should be modifying
+// this state and not the input stream itself.
+struct nsPipeReadState {
+  nsPipeReadState()
+      : mReadCursor(nullptr),
+        mReadLimit(nullptr),
+        mSegment(0),
+        mAvailable(0),
+        mActiveRead(false),
+        mNeedDrain(false) {}
+
+  // All members of this type are guarded by the pipe monitor, however it cannot
+  // be named from this type, so the less-reliable MOZ_GUARDED_VAR is used
+  // instead. In the future it would be nice to avoid this, especially as
+  // MOZ_GUARDED_VAR is deprecated.
+  char* mReadCursor MOZ_GUARDED_VAR;
+  char* mReadLimit MOZ_GUARDED_VAR;
+  int32_t mSegment MOZ_GUARDED_VAR;
+  uint32_t mAvailable MOZ_GUARDED_VAR;
+
+  // This flag is managed using the AutoReadSegment RAII stack class.
+  bool mActiveRead MOZ_GUARDED_VAR;
+
+  // Set to indicate that the input stream has closed and should be drained,
+  // but that drain has been delayed due to an active read.  When the read
+  // completes, this flag indicate the drain should then be performed.
+  bool mNeedDrain MOZ_GUARDED_VAR;
+};
+
+//-----------------------------------------------------------------------------
+
+// an input end of a pipe (maintained as a list of refs within the pipe)
+class nsPipeInputStream final : public nsIAsyncInputStream,
+                                public nsITellableStream,
+                                public nsISearchableInputStream,
+                                public nsICloneableInputStream,
+                                public nsIClassInfo,
+                                public nsIBufferedInputStream,
+                                public nsIInputStreamPriority {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIASYNCINPUTSTREAM
+  NS_DECL_NSITELLABLESTREAM
+  NS_DECL_NSISEARCHABLEINPUTSTREAM
+  NS_DECL_NSICLONEABLEINPUTSTREAM
+  NS_DECL_NSICLASSINFO
+  NS_DECL_NSIBUFFEREDINPUTSTREAM
+  NS_DECL_NSIINPUTSTREAMPRIORITY
+
+  explicit nsPipeInputStream(nsPipe* aPipe)
+      : mPipe(aPipe),
+        mLogicalOffset(0),
+        mInputStatus(NS_OK),
+        mBlocking(true),
+        mBlocked(false),
+        mPriority(nsIRunnablePriority::PRIORITY_NORMAL) {}
+
+  nsPipeInputStream(const nsPipeInputStream& aOther)
+      : mPipe(aOther.mPipe),
+        mLogicalOffset(aOther.mLogicalOffset),
+        mInputStatus(aOther.mInputStatus),
+        mBlocking(aOther.mBlocking),
+        mBlocked(false),
+        mReadState(aOther.mReadState),
+        mPriority(nsIRunnablePriority::PRIORITY_NORMAL) {}
+
+  void SetNonBlocking(bool aNonBlocking) { mBlocking = !aNonBlocking; }
+
+  uint32_t Available() MOZ_REQUIRES(Monitor());
+
+  // synchronously wait for the pipe to become readable.
+  nsresult Wait();
+
+  // These two don't acquire the monitor themselves.  Instead they
+  // expect their caller to have done so and to pass the monitor as
+  // evidence.
+  MonitorAction OnInputReadable(uint32_t aBytesWritten, nsPipeEvents&,
+                                const ReentrantMonitorAutoEnter& ev)
+      MOZ_REQUIRES(Monitor());
+  MonitorAction OnInputException(nsresult, nsPipeEvents&,
+                                 const ReentrantMonitorAutoEnter& ev)
+      MOZ_REQUIRES(Monitor());
+
+  nsPipeReadState& ReadState() { return mReadState; }
+
+  const nsPipeReadState& ReadState() const { return mReadState; }
+
+  nsresult Status() const;
+
+  // A version of Status() that doesn't acquire the monitor.
+  nsresult Status(const ReentrantMonitorAutoEnter& ev) const
+      MOZ_REQUIRES(Monitor());
+
+  // The status of this input stream, ignoring the status of the underlying
+  // monitor. If this status is errored, the input stream has either already
+  // been removed from the pipe, or will be removed from the pipe shortly.
+  nsresult InputStatus(const ReentrantMonitorAutoEnter&) const
+      MOZ_REQUIRES(Monitor()) {
+    return mInputStatus;
+  }
+
+  ReentrantMonitor& Monitor() const;
+
+ private:
+  virtual ~nsPipeInputStream();
+
+  RefPtr<nsPipe> mPipe;
+
+  int64_t mLogicalOffset;
+  // Individual input streams can be closed without effecting the rest of the
+  // pipe.  So track individual input stream status separately.  |mInputStatus|
+  // is protected by |mPipe->mReentrantMonitor|.
+  nsresult mInputStatus MOZ_GUARDED_BY(Monitor());
+  bool mBlocking;
+
+  // these variables can only be accessed while inside the pipe's monitor
+  bool mBlocked MOZ_GUARDED_BY(Monitor());
+  CallbackHolder mCallback MOZ_GUARDED_BY(Monitor());
+
+  // requires pipe's monitor to access members; usually treat as an opaque token
+  // to pass to nsPipe
+  nsPipeReadState mReadState;
+  Atomic<uint32_t, Relaxed> mPriority;
+};
+
+//-----------------------------------------------------------------------------
+
+// the output end of a pipe (allocated as a member of the pipe).
+class nsPipeOutputStream : public nsIAsyncOutputStream, public nsIClassInfo {
+ public:
+  // since this class will be allocated as a member of the pipe, we do not
+  // need our own ref count.  instead, we share the lifetime (the ref count)
+  // of the entire pipe.  this macro is just convenience since it does not
+  // declare a mRefCount variable; however, don't let the name fool you...
+  // we are not inheriting from nsPipe ;-)
+  NS_DECL_ISUPPORTS_INHERITED
+
+  NS_DECL_NSIOUTPUTSTREAM
+  NS_DECL_NSIASYNCOUTPUTSTREAM
+  NS_DECL_NSICLASSINFO
+
+  explicit nsPipeOutputStream(nsPipe* aPipe)
+      : mPipe(aPipe),
+        mWriterRefCnt(0),
+        mLogicalOffset(0),
+        mBlocking(true),
+        mBlocked(false),
+        mWritable(true) {}
+
+  void SetNonBlocking(bool aNonBlocking) { mBlocking = !aNonBlocking; }
+  void SetWritable(bool aWritable) MOZ_REQUIRES(Monitor()) {
+    mWritable = aWritable;
+  }
+
+  // synchronously wait for the pipe to become writable.
+  nsresult Wait();
+
+  MonitorAction OnOutputWritable(nsPipeEvents&) MOZ_REQUIRES(Monitor());
+  MonitorAction OnOutputException(nsresult, nsPipeEvents&)
+      MOZ_REQUIRES(Monitor());
+
+  ReentrantMonitor& Monitor() const;
+
+ private:
+  nsPipe* mPipe;
+
+  // separate refcnt so that we know when to close the producer
+  ThreadSafeAutoRefCnt mWriterRefCnt;
+  int64_t mLogicalOffset;
+  bool mBlocking;
+
+  // these variables can only be accessed while inside the pipe's monitor
+  bool mBlocked MOZ_GUARDED_BY(Monitor());
+  bool mWritable MOZ_GUARDED_BY(Monitor());
+  CallbackHolder mCallback MOZ_GUARDED_BY(Monitor());
+};
+
+//-----------------------------------------------------------------------------
+
+class nsPipe final {
+ public:
+  friend class nsPipeInputStream;
+  friend class nsPipeOutputStream;
+  friend class AutoReadSegment;
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(nsPipe)
+
+  // public constructor
+  friend void NS_NewPipe2(nsIAsyncInputStream**, nsIAsyncOutputStream**, bool,
+                          bool, uint32_t, uint32_t);
+
+ private:
+  nsPipe(uint32_t aSegmentSize, uint32_t aSegmentCount);
+  ~nsPipe();
+
+  //
+  // Methods below may only be called while inside the pipe's monitor.  Some
+  // of these methods require passing a ReentrantMonitorAutoEnter to prove the
+  // monitor is held.
+  //
+
+  void PeekSegment(const nsPipeReadState& aReadState, uint32_t aIndex,
+                   char*& aCursor, char*& aLimit)
+      MOZ_REQUIRES(mReentrantMonitor);
+  SegmentChangeResult AdvanceReadSegment(nsPipeReadState& aReadState,
+                                         const ReentrantMonitorAutoEnter& ev)
+      MOZ_REQUIRES(mReentrantMonitor);
+  bool ReadSegmentBeingWritten(nsPipeReadState& aReadState)
+      MOZ_REQUIRES(mReentrantMonitor);
+  uint32_t CountSegmentReferences(int32_t aSegment)
+      MOZ_REQUIRES(mReentrantMonitor);
+  void SetAllNullReadCursors() MOZ_REQUIRES(mReentrantMonitor);
+  bool AllReadCursorsMatchWriteCursor() MOZ_REQUIRES(mReentrantMonitor);
+  void RollBackAllReadCursors(char* aWriteCursor)
+      MOZ_REQUIRES(mReentrantMonitor);
+  void UpdateAllReadCursors(char* aWriteCursor) MOZ_REQUIRES(mReentrantMonitor);
+  void ValidateAllReadCursors() MOZ_REQUIRES(mReentrantMonitor);
+  uint32_t GetBufferSegmentCount(const nsPipeReadState& aReadState,
+                                 const ReentrantMonitorAutoEnter& ev) const
+      MOZ_REQUIRES(mReentrantMonitor);
+  bool IsAdvanceBufferFull(const ReentrantMonitorAutoEnter& ev) const
+      MOZ_REQUIRES(mReentrantMonitor);
+
+  //
+  // methods below may be called while outside the pipe's monitor
+  //
+
+  void DrainInputStream(nsPipeReadState& aReadState, nsPipeEvents& aEvents);
+  nsresult GetWriteSegment(char*& aSegment, uint32_t& aSegmentLen);
+  void AdvanceWriteCursor(uint32_t aCount);
+
+  void OnInputStreamException(nsPipeInputStream* aStream, nsresult aReason);
+  void OnPipeException(nsresult aReason, bool aOutputOnly = false);
+
+  nsresult CloneInputStream(nsPipeInputStream* aOriginal,
+                            nsIInputStream** aCloneOut);
+
+  // methods below should only be called by AutoReadSegment
+  nsresult GetReadSegment(nsPipeReadState& aReadState, const char*& aSegment,
+                          uint32_t& aLength);
+  void ReleaseReadSegment(nsPipeReadState& aReadState, nsPipeEvents& aEvents);
+  void AdvanceReadCursor(nsPipeReadState& aReadState, uint32_t aCount);
+
+  // We can't inherit from both nsIInputStream and nsIOutputStream
+  // because they collide on their Close method. Consequently we nest their
+  // implementations to avoid the extra object allocation.
+  nsPipeOutputStream mOutput;
+
+  // Since the input stream can be cloned, we may have more than one.  Use
+  // a weak reference as the streams will clear their entry here in their
+  // destructor.  Using a strong reference would create a reference cycle.
+  // Only usable while mReentrantMonitor is locked.
+  nsTArray<nsPipeInputStream*> mInputList MOZ_GUARDED_BY(mReentrantMonitor);
+
+  ReentrantMonitor mReentrantMonitor;
+  nsSegmentedBuffer mBuffer MOZ_GUARDED_BY(mReentrantMonitor);
+
+  // The maximum number of segments to allow to be buffered in advance
+  // of the fastest reader.  This is collection of segments is called
+  // the "advance buffer".
+  uint32_t mMaxAdvanceBufferSegmentCount MOZ_GUARDED_BY(mReentrantMonitor);
+
+  int32_t mWriteSegment MOZ_GUARDED_BY(mReentrantMonitor);
+  char* mWriteCursor MOZ_GUARDED_BY(mReentrantMonitor);
+  char* mWriteLimit MOZ_GUARDED_BY(mReentrantMonitor);
+
+  // |mStatus| is protected by |mReentrantMonitor|.
+  nsresult mStatus MOZ_GUARDED_BY(mReentrantMonitor);
+};
+
+//-----------------------------------------------------------------------------
+
+// Declarations of Monitor() methods on the streams.
+//
+// These must be placed early to provide MOZ_RETURN_CAPABILITY annotations for
+// the thread-safety analysis. This couldn't be done at the declaration due to
+// nsPipe not yet being defined.
+
+ReentrantMonitor& nsPipeOutputStream::Monitor() const
+    MOZ_RETURN_CAPABILITY(mPipe->mReentrantMonitor) {
+  return mPipe->mReentrantMonitor;
+}
+
+ReentrantMonitor& nsPipeInputStream::Monitor() const
+    MOZ_RETURN_CAPABILITY(mPipe->mReentrantMonitor) {
+  return mPipe->mReentrantMonitor;
+}
+
+//-----------------------------------------------------------------------------
+
+// RAII class representing an active read segment.  When it goes out of scope
+// it automatically updates the read cursor and releases the read segment.
+class MOZ_STACK_CLASS AutoReadSegment final {
+ public:
+  AutoReadSegment(nsPipe* aPipe, nsPipeReadState& aReadState,
+                  uint32_t aMaxLength)
+      : mPipe(aPipe),
+        mReadState(aReadState),
+        mStatus(NS_ERROR_FAILURE),
+        mSegment(nullptr),
+        mLength(0),
+        mOffset(0) {
+    MOZ_DIAGNOSTIC_ASSERT(mPipe);
+    MOZ_DIAGNOSTIC_ASSERT(!mReadState.mActiveRead);
+    mStatus = mPipe->GetReadSegment(mReadState, mSegment, mLength);
+    if (NS_SUCCEEDED(mStatus)) {
+      MOZ_DIAGNOSTIC_ASSERT(mReadState.mActiveRead);
+      MOZ_DIAGNOSTIC_ASSERT(mSegment);
+      mLength = std::min(mLength, aMaxLength);
+      MOZ_DIAGNOSTIC_ASSERT(mLength);
+    }
+  }
+
+  ~AutoReadSegment() {
+    if (NS_SUCCEEDED(mStatus)) {
+      if (mOffset) {
+        mPipe->AdvanceReadCursor(mReadState, mOffset);
+      } else {
+        nsPipeEvents events;
+        mPipe->ReleaseReadSegment(mReadState, events);
+      }
+    }
+    MOZ_DIAGNOSTIC_ASSERT(!mReadState.mActiveRead);
+  }
+
+  nsresult Status() const { return mStatus; }
+
+  const char* Data() const {
+    MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(mStatus));
+    MOZ_DIAGNOSTIC_ASSERT(mSegment);
+    return mSegment + mOffset;
+  }
+
+  uint32_t Length() const {
+    MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(mStatus));
+    MOZ_DIAGNOSTIC_ASSERT(mLength >= mOffset);
+    return mLength - mOffset;
+  }
+
+  void Advance(uint32_t aCount) {
+    MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(mStatus));
+    MOZ_DIAGNOSTIC_ASSERT(aCount <= (mLength - mOffset));
+    mOffset += aCount;
+  }
+
+  nsPipeReadState& ReadState() const { return mReadState; }
+
+ private:
+  // guaranteed to remain alive due to limited stack lifetime of AutoReadSegment
+  nsPipe* mPipe;
+  nsPipeReadState& mReadState;
+  nsresult mStatus;
+  const char* mSegment;
+  uint32_t mLength;
+  uint32_t mOffset;
+};
+
+//
+// NOTES on buffer architecture:
+//
+//       +-----------------+ - - mBuffer.GetSegment(0)
+//       |                 |
+//       + - - - - - - - - + - - nsPipeReadState.mReadCursor
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       +-----------------+ - - nsPipeReadState.mReadLimit
+//                |
+//       +-----------------+
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       +-----------------+
+//                |
+//       +-----------------+ - - mBuffer.GetSegment(mWriteSegment)
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       + - - - - - - - - + - - mWriteCursor
+//       |                 |
+//       |                 |
+//       +-----------------+ - - mWriteLimit
+//
+// (shaded region contains data)
+//
+// NOTE: Each input stream produced by the nsPipe contains its own, separate
+//       nsPipeReadState.  This means there are multiple mReadCursor and
+//       mReadLimit values in play.  The pipe cannot discard old data until
+//       all mReadCursors have moved beyond that point in the stream.
+//
+//       Likewise, each input stream reader will have it's own amount of
+//       buffered data.  The pipe size threshold, however, is only applied
+//       to the input stream that is being read fastest.  We call this
+//       the "advance buffer" in that its in advance of all readers.  We
+//       allow slower input streams to buffer more data so that we don't
+//       stall processing of the faster input stream.
+//
+// NOTE: on some systems (notably OS/2), the heap allocator uses an arena for
+// small allocations (e.g., 64 byte allocations).  this means that buffers may
+// be allocated back-to-back.  in the diagram above, for example, mReadLimit
+// would actually be pointing at the beginning of the next segment.  when
+// making changes to this file, please keep this fact in mind.
+//
+
+//-----------------------------------------------------------------------------
+// nsPipe methods:
+//-----------------------------------------------------------------------------
+
+nsPipe::nsPipe(uint32_t aSegmentSize, uint32_t aSegmentCount)
+    : mOutput(this),
+      mReentrantMonitor("nsPipe.mReentrantMonitor"),
+      // protect against overflow
+      mMaxAdvanceBufferSegmentCount(
+          std::min(aSegmentCount, UINT32_MAX / aSegmentSize)),
+      mWriteSegment(-1),
+      mWriteCursor(nullptr),
+      mWriteLimit(nullptr),
+      mStatus(NS_OK) {
+  // The internal buffer is always "infinite" so that we can allow
+  // the size to expand when cloned streams are read at different
+  // rates.  We enforce a limit on how much data can be buffered
+  // ahead of the fastest reader in GetWriteSegment().
+  MOZ_ALWAYS_SUCCEEDS(mBuffer.Init(aSegmentSize));
+}
+
+nsPipe::~nsPipe() = default;
+
+void nsPipe::PeekSegment(const nsPipeReadState& aReadState, uint32_t aIndex,
+                         char*& aCursor, char*& aLimit) {
+  if (aIndex == 0) {
+    MOZ_DIAGNOSTIC_ASSERT(!aReadState.mReadCursor || mBuffer.GetSegmentCount());
+    aCursor = aReadState.mReadCursor;
+    aLimit = aReadState.mReadLimit;
+  } else {
+    uint32_t absoluteIndex = aReadState.mSegment + aIndex;
+    uint32_t numSegments = mBuffer.GetSegmentCount();
+    if (absoluteIndex >= numSegments) {
+      aCursor = aLimit = nullptr;
+    } else {
+      aCursor = mBuffer.GetSegment(absoluteIndex);
+      if (mWriteSegment == (int32_t)absoluteIndex) {
+        aLimit = mWriteCursor;
+      } else {
+        aLimit = aCursor + mBuffer.GetSegmentSize();
+      }
+    }
+  }
+}
+
+nsresult nsPipe::GetReadSegment(nsPipeReadState& aReadState,
+                                const char*& aSegment, uint32_t& aLength) {
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+  if (aReadState.mReadCursor == aReadState.mReadLimit) {
+    return NS_FAILED(mStatus) ? mStatus : NS_BASE_STREAM_WOULD_BLOCK;
+  }
+
+  // The input stream locks the pipe while getting the buffer to read from,
+  // but then unlocks while actual data copying is taking place.  In
+  // order to avoid deleting the buffer out from under this lockless read
+  // set a flag to indicate a read is active.  This flag is only modified
+  // while the lock is held.
+  MOZ_DIAGNOSTIC_ASSERT(!aReadState.mActiveRead);
+  aReadState.mActiveRead = true;
+
+  aSegment = aReadState.mReadCursor;
+  aLength = aReadState.mReadLimit - aReadState.mReadCursor;
+  MOZ_DIAGNOSTIC_ASSERT(aLength <= aReadState.mAvailable);
+
+  return NS_OK;
+}
+
+void nsPipe::ReleaseReadSegment(nsPipeReadState& aReadState,
+                                nsPipeEvents& aEvents) {
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+  MOZ_DIAGNOSTIC_ASSERT(aReadState.mActiveRead);
+  aReadState.mActiveRead = false;
+
+  // When a read completes and releases the mActiveRead flag, we may have
+  // blocked a drain from completing.  This occurs when the input stream is
+  // closed during the read.  In these cases, we need to complete the drain as
+  // soon as the active read completes.
+  if (aReadState.mNeedDrain) {
+    aReadState.mNeedDrain = false;
+    DrainInputStream(aReadState, aEvents);
+  }
+}
+
+void nsPipe::AdvanceReadCursor(nsPipeReadState& aReadState,
+                               uint32_t aBytesRead) {
+  MOZ_DIAGNOSTIC_ASSERT(aBytesRead > 0);
+
+  nsPipeEvents events;
+  {
+    ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+    LOG(("III advancing read cursor by %u\n", aBytesRead));
+    MOZ_DIAGNOSTIC_ASSERT(aBytesRead <= mBuffer.GetSegmentSize());
+
+    aReadState.mReadCursor += aBytesRead;
+    MOZ_DIAGNOSTIC_ASSERT(aReadState.mReadCursor <= aReadState.mReadLimit);
+
+    MOZ_DIAGNOSTIC_ASSERT(aReadState.mAvailable >= aBytesRead);
+    aReadState.mAvailable -= aBytesRead;
+
+    // Check to see if we're at the end of the available read data.  If we
+    // are, and this segment is not still being written, then we can possibly
+    // free up the segment.
+    if (aReadState.mReadCursor == aReadState.mReadLimit &&
+        !ReadSegmentBeingWritten(aReadState)) {
+      // Advance the segment position.  If we have read any segments from the
+      // advance buffer then we can potentially notify blocked writers.
+      mOutput.Monitor().AssertCurrentThreadIn();
+      if (AdvanceReadSegment(aReadState, mon) == SegmentAdvanceBufferRead &&
+          mOutput.OnOutputWritable(events) == NotifyMonitor) {
+        mon.NotifyAll();
+      }
+    }
+
+    ReleaseReadSegment(aReadState, events);
+  }
+}
+
+SegmentChangeResult nsPipe::AdvanceReadSegment(
+    nsPipeReadState& aReadState, const ReentrantMonitorAutoEnter& ev) {
+  // Calculate how many segments are buffered for this stream to start.
+  uint32_t startBufferSegments = GetBufferSegmentCount(aReadState, ev);
+
+  int32_t currentSegment = aReadState.mSegment;
+
+  // Move to the next segment to read
+  aReadState.mSegment += 1;
+
+  // If this was the last reference to the first segment, then remove it.
+  if (currentSegment == 0 && CountSegmentReferences(currentSegment) == 0) {
+    // shift write and read segment index (-1 indicates an empty buffer).
+    mWriteSegment -= 1;
+
+    // Directly modify the current read state.  If the associated input
+    // stream is closed simultaneous with reading, then it may not be
+    // in the mInputList any more.
+    aReadState.mSegment -= 1;
+
+    for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+      // Skip the current read state structure since we modify it manually
+      // before entering this loop.
+      if (&mInputList[i]->ReadState() == &aReadState) {
+        continue;
+      }
+      mInputList[i]->ReadState().mSegment -= 1;
+    }
+
+    // done with this segment
+    mBuffer.DeleteFirstSegment();
+    LOG(("III deleting first segment\n"));
+  }
+
+  if (mWriteSegment < aReadState.mSegment) {
+    // read cursor has hit the end of written data, so reset it
+    MOZ_DIAGNOSTIC_ASSERT(mWriteSegment == (aReadState.mSegment - 1));
+    aReadState.mReadCursor = nullptr;
+    aReadState.mReadLimit = nullptr;
+    // also, the buffer is completely empty, so reset the write cursor
+    if (mWriteSegment == -1) {
+      mWriteCursor = nullptr;
+      mWriteLimit = nullptr;
+    }
+  } else {
+    // advance read cursor and limit to next buffer segment
+    aReadState.mReadCursor = mBuffer.GetSegment(aReadState.mSegment);
+    if (mWriteSegment == aReadState.mSegment) {
+      aReadState.mReadLimit = mWriteCursor;
+    } else {
+      aReadState.mReadLimit = aReadState.mReadCursor + mBuffer.GetSegmentSize();
+    }
+  }
+
+  // Calculate how many segments are buffered for the stream after
+  // reading.
+  uint32_t endBufferSegments = GetBufferSegmentCount(aReadState, ev);
+
+  // If the stream has read a segment out of the set of advanced buffer
+  // segments, then the writer may advance.
+  if (startBufferSegments >= mMaxAdvanceBufferSegmentCount &&
+      endBufferSegments < mMaxAdvanceBufferSegmentCount) {
+    return SegmentAdvanceBufferRead;
+  }
+
+  // Otherwise there are no significant changes to the segment structure.
+  return SegmentNotChanged;
+}
+
+void nsPipe::DrainInputStream(nsPipeReadState& aReadState,
+                              nsPipeEvents& aEvents) {
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+  // If a segment is actively being read in ReadSegments() for this input
+  // stream, then we cannot drain the stream.  This can happen because
+  // ReadSegments() does not hold the lock while copying from the buffer.
+  // If we detect this condition, simply note that we need a drain once
+  // the read completes and return immediately.
+  if (aReadState.mActiveRead) {
+    MOZ_DIAGNOSTIC_ASSERT(!aReadState.mNeedDrain);
+    aReadState.mNeedDrain = true;
+    return;
+  }
+
+  while (mWriteSegment >= aReadState.mSegment) {
+    // If the last segment to free is still being written to, we're done
+    // draining.  We can't free any more.
+    if (ReadSegmentBeingWritten(aReadState)) {
+      break;
+    }
+
+    // Don't bother checking if this results in an advance buffer segment
+    // read.  Since we are draining the entire stream we will read an
+    // advance buffer segment no matter what.
+    AdvanceReadSegment(aReadState, mon);
+  }
+
+  // Force the stream into an empty state.  Make sure mAvailable, mCursor, and
+  // mReadLimit are consistent with one another.
+  aReadState.mAvailable = 0;
+  aReadState.mReadCursor = nullptr;
+  aReadState.mReadLimit = nullptr;
+
+  // Remove the input stream from the pipe's list of streams.  This will
+  // prevent the pipe from holding the stream alive or trying to update
+  // its read state any further.
+  DebugOnly<uint32_t> numRemoved = 0;
+  mInputList.RemoveElementsBy([&](nsPipeInputStream* aEntry) {
+    bool result = &aReadState == &aEntry->ReadState();
+    numRemoved += result ? 1 : 0;
+    return result;
+  });
+  MOZ_ASSERT(numRemoved == 1);
+
+  // If we have read any segments from the advance buffer then we can
+  // potentially notify blocked writers.
+  mOutput.Monitor().AssertCurrentThreadIn();
+  if (!IsAdvanceBufferFull(mon) &&
+      mOutput.OnOutputWritable(aEvents) == NotifyMonitor) {
+    mon.NotifyAll();
+  }
+}
+
+bool nsPipe::ReadSegmentBeingWritten(nsPipeReadState& aReadState) {
+  mReentrantMonitor.AssertCurrentThreadIn();
+  bool beingWritten =
+      mWriteSegment == aReadState.mSegment && mWriteLimit > mWriteCursor;
+  MOZ_DIAGNOSTIC_ASSERT(!beingWritten || aReadState.mReadLimit == mWriteCursor);
+  return beingWritten;
+}
+
+nsresult nsPipe::GetWriteSegment(char*& aSegment, uint32_t& aSegmentLen) {
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  // write cursor and limit may both be null indicating an empty buffer.
+  if (mWriteCursor == mWriteLimit) {
+    // The pipe is full if we have hit our limit on advance data buffering.
+    // This means the fastest reader is still reading slower than data is
+    // being written into the pipe.
+    if (IsAdvanceBufferFull(mon)) {
+      return NS_BASE_STREAM_WOULD_BLOCK;
+    }
+
+    // The nsSegmentedBuffer is configured to be "infinite", so this
+    // should never return nullptr here.
+    char* seg = mBuffer.AppendNewSegment();
+    if (!seg) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    LOG(("OOO appended new segment\n"));
+    mWriteCursor = seg;
+    mWriteLimit = mWriteCursor + mBuffer.GetSegmentSize();
+    ++mWriteSegment;
+  }
+
+  // make sure read cursor is initialized
+  SetAllNullReadCursors();
+
+  // check to see if we can roll-back our read and write cursors to the
+  // beginning of the current/first segment.  this is purely an optimization.
+  if (mWriteSegment == 0 && AllReadCursorsMatchWriteCursor()) {
+    char* head = mBuffer.GetSegment(0);
+    LOG(("OOO rolling back write cursor %" PRId64 " bytes\n",
+         static_cast<int64_t>(mWriteCursor - head)));
+    RollBackAllReadCursors(head);
+    mWriteCursor = head;
+  }
+
+  aSegment = mWriteCursor;
+  aSegmentLen = mWriteLimit - mWriteCursor;
+  return NS_OK;
+}
+
+void nsPipe::AdvanceWriteCursor(uint32_t aBytesWritten) {
+  MOZ_DIAGNOSTIC_ASSERT(aBytesWritten > 0);
+
+  nsPipeEvents events;
+  {
+    ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+    LOG(("OOO advancing write cursor by %u\n", aBytesWritten));
+
+    char* newWriteCursor = mWriteCursor + aBytesWritten;
+    MOZ_DIAGNOSTIC_ASSERT(newWriteCursor <= mWriteLimit);
+
+    // update read limit if reading in the same segment
+    UpdateAllReadCursors(newWriteCursor);
+
+    mWriteCursor = newWriteCursor;
+
+    ValidateAllReadCursors();
+
+    // update the writable flag on the output stream
+    if (mWriteCursor == mWriteLimit) {
+      mOutput.Monitor().AssertCurrentThreadIn();
+      mOutput.SetWritable(!IsAdvanceBufferFull(mon));
+    }
+
+    // notify input stream that pipe now contains additional data
+    bool needNotify = false;
+    for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+      mInputList[i]->Monitor().AssertCurrentThreadIn();
+      if (mInputList[i]->OnInputReadable(aBytesWritten, events, mon) ==
+          NotifyMonitor) {
+        needNotify = true;
+      }
+    }
+
+    if (needNotify) {
+      mon.NotifyAll();
+    }
+  }
+}
+
+void nsPipe::OnInputStreamException(nsPipeInputStream* aStream,
+                                    nsresult aReason) {
+  MOZ_DIAGNOSTIC_ASSERT(NS_FAILED(aReason));
+
+  nsPipeEvents events;
+  {
+    ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+    // Its possible to re-enter this method when we call OnPipeException() or
+    // OnInputExection() below.  If there is a caller stuck in our synchronous
+    // Wait() method, then they will get woken up with a failure code which
+    // re-enters this method.  Therefore, gracefully handle unknown streams
+    // here.
+
+    // If we only have one stream open and it is the given stream, then shut
+    // down the entire pipe.
+    if (mInputList.Length() == 1) {
+      if (mInputList[0] == aStream) {
+        OnPipeException(aReason);
+      }
+      return;
+    }
+
+    // Otherwise just close the particular stream that hit an exception.
+    for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+      if (mInputList[i] != aStream) {
+        continue;
+      }
+
+      mInputList[i]->Monitor().AssertCurrentThreadIn();
+      MonitorAction action =
+          mInputList[i]->OnInputException(aReason, events, mon);
+
+      // Notify after element is removed in case we re-enter as a result.
+      if (action == NotifyMonitor) {
+        mon.NotifyAll();
+      }
+
+      return;
+    }
+  }
+}
+
+void nsPipe::OnPipeException(nsresult aReason, bool aOutputOnly) {
+  LOG(("PPP nsPipe::OnPipeException [reason=%" PRIx32 " output-only=%d]\n",
+       static_cast<uint32_t>(aReason), aOutputOnly));
+
+  nsPipeEvents events;
+  {
+    ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+    // if we've already hit an exception, then ignore this one.
+    if (NS_FAILED(mStatus)) {
+      return;
+    }
+
+    mStatus = aReason;
+
+    bool needNotify = false;
+
+    // OnInputException() can drain the stream and remove it from
+    // mInputList.  So iterate over a temp list instead.
+    nsTArray<nsPipeInputStream*> list = mInputList.Clone();
+    for (uint32_t i = 0; i < list.Length(); ++i) {
+      // an output-only exception applies to the input end if the pipe has
+      // zero bytes available.
+      list[i]->Monitor().AssertCurrentThreadIn();
+      if (aOutputOnly && list[i]->Available()) {
+        continue;
+      }
+
+      if (list[i]->OnInputException(aReason, events, mon) == NotifyMonitor) {
+        needNotify = true;
+      }
+    }
+
+    mOutput.Monitor().AssertCurrentThreadIn();
+    if (mOutput.OnOutputException(aReason, events) == NotifyMonitor) {
+      needNotify = true;
+    }
+
+    // Notify after we have removed any input streams from mInputList
+    if (needNotify) {
+      mon.NotifyAll();
+    }
+  }
+}
+
+nsresult nsPipe::CloneInputStream(nsPipeInputStream* aOriginal,
+                                  nsIInputStream** aCloneOut) {
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+  RefPtr<nsPipeInputStream> ref = new nsPipeInputStream(*aOriginal);
+  // don't add clones of closed pipes to mInputList.
+  ref->Monitor().AssertCurrentThreadIn();
+  if (NS_SUCCEEDED(ref->InputStatus(mon))) {
+    mInputList.AppendElement(ref);
+  }
+  nsCOMPtr<nsIAsyncInputStream> upcast = std::move(ref);
+  upcast.forget(aCloneOut);
+  return NS_OK;
+}
+
+uint32_t nsPipe::CountSegmentReferences(int32_t aSegment) {
+  mReentrantMonitor.AssertCurrentThreadIn();
+  uint32_t count = 0;
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    if (aSegment >= mInputList[i]->ReadState().mSegment) {
+      count += 1;
+    }
+  }
+  return count;
+}
+
+void nsPipe::SetAllNullReadCursors() {
+  mReentrantMonitor.AssertCurrentThreadIn();
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    nsPipeReadState& readState = mInputList[i]->ReadState();
+    if (!readState.mReadCursor) {
+      MOZ_DIAGNOSTIC_ASSERT(mWriteSegment == readState.mSegment);
+      readState.mReadCursor = readState.mReadLimit = mWriteCursor;
+    }
+  }
+}
+
+bool nsPipe::AllReadCursorsMatchWriteCursor() {
+  mReentrantMonitor.AssertCurrentThreadIn();
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    const nsPipeReadState& readState = mInputList[i]->ReadState();
+    if (readState.mSegment != mWriteSegment ||
+        readState.mReadCursor != mWriteCursor) {
+      return false;
+    }
+  }
+  return true;
+}
+
+void nsPipe::RollBackAllReadCursors(char* aWriteCursor) {
+  mReentrantMonitor.AssertCurrentThreadIn();
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    nsPipeReadState& readState = mInputList[i]->ReadState();
+    MOZ_DIAGNOSTIC_ASSERT(mWriteSegment == readState.mSegment);
+    MOZ_DIAGNOSTIC_ASSERT(mWriteCursor == readState.mReadCursor);
+    MOZ_DIAGNOSTIC_ASSERT(mWriteCursor == readState.mReadLimit);
+    readState.mReadCursor = aWriteCursor;
+    readState.mReadLimit = aWriteCursor;
+  }
+}
+
+void nsPipe::UpdateAllReadCursors(char* aWriteCursor) {
+  mReentrantMonitor.AssertCurrentThreadIn();
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    nsPipeReadState& readState = mInputList[i]->ReadState();
+    if (mWriteSegment == readState.mSegment &&
+        readState.mReadLimit == mWriteCursor) {
+      readState.mReadLimit = aWriteCursor;
+    }
+  }
+}
+
+void nsPipe::ValidateAllReadCursors() {
+  mReentrantMonitor.AssertCurrentThreadIn();
+  // The only way mReadCursor == mWriteCursor is if:
+  //
+  // - mReadCursor is at the start of a segment (which, based on how
+  //   nsSegmentedBuffer works, means that this segment is the "first"
+  //   segment)
+  // - mWriteCursor points at the location past the end of the current
+  //   write segment (so the current write filled the current write
+  //   segment, so we've incremented mWriteCursor to point past the end
+  //   of it)
+  // - the segment to which data has just been written is located
+  //   exactly one segment's worth of bytes before the first segment
+  //   where mReadCursor is located
+  //
+  // Consequently, the byte immediately after the end of the current
+  // write segment is the first byte of the first segment, so
+  // mReadCursor == mWriteCursor.  (Another way to think about this is
+  // to consider the buffer architecture diagram above, but consider it
+  // with an arena allocator which allocates from the *end* of the
+  // arena to the *beginning* of the arena.)
+#ifdef DEBUG
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    const nsPipeReadState& state = mInputList[i]->ReadState();
+    MOZ_ASSERT(state.mReadCursor != mWriteCursor ||
+               (mBuffer.GetSegment(state.mSegment) == state.mReadCursor &&
+                mWriteCursor == mWriteLimit));
+  }
+#endif
+}
+
+uint32_t nsPipe::GetBufferSegmentCount(
+    const nsPipeReadState& aReadState,
+    const ReentrantMonitorAutoEnter& ev) const {
+  // The write segment can be smaller than the current reader position
+  // in some cases.  For example, when the first write segment has not
+  // been allocated yet mWriteSegment is negative.  In these cases
+  // the stream is effectively using zero segments.
+  if (mWriteSegment < aReadState.mSegment) {
+    return 0;
+  }
+
+  MOZ_DIAGNOSTIC_ASSERT(mWriteSegment >= 0);
+  MOZ_DIAGNOSTIC_ASSERT(aReadState.mSegment >= 0);
+
+  // Otherwise at least one segment is being used.  We add one here
+  // since a single segment is being used when the write and read
+  // segment indices are the same.
+  return 1 + mWriteSegment - aReadState.mSegment;
+}
+
+bool nsPipe::IsAdvanceBufferFull(const ReentrantMonitorAutoEnter& ev) const {
+  // If we have fewer total segments than the limit we can immediately
+  // determine we are not full.  Note, we must add one to mWriteSegment
+  // to convert from a index to a count.
+  MOZ_DIAGNOSTIC_ASSERT(mWriteSegment >= -1);
+  MOZ_DIAGNOSTIC_ASSERT(mWriteSegment < INT32_MAX);
+  uint32_t totalWriteSegments = mWriteSegment + 1;
+  if (totalWriteSegments < mMaxAdvanceBufferSegmentCount) {
+    return false;
+  }
+
+  // Otherwise we must inspect all of our reader streams.  We need
+  // to determine the buffer depth of the fastest reader.
+  uint32_t minBufferSegments = UINT32_MAX;
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    // Only count buffer segments from input streams that are open.
+    mInputList[i]->Monitor().AssertCurrentThreadIn();
+    if (NS_FAILED(mInputList[i]->Status(ev))) {
+      continue;
+    }
+    const nsPipeReadState& state = mInputList[i]->ReadState();
+    uint32_t bufferSegments = GetBufferSegmentCount(state, ev);
+    minBufferSegments = std::min(minBufferSegments, bufferSegments);
+    // We only care if any reader has fewer segments buffered than
+    // our threshold.  We can stop once we hit that threshold.
+    if (minBufferSegments < mMaxAdvanceBufferSegmentCount) {
+      return false;
+    }
+  }
+
+  // Note, its possible for minBufferSegments to exceed our
+  // mMaxAdvanceBufferSegmentCount here.  This happens when a cloned
+  // reader gets far behind, but then the fastest reader stream is
+  // closed.  This leaves us with a single stream that is buffered
+  // beyond our max.  Naturally we continue to indicate the pipe
+  // is full at this point.
+
+  return true;
+}
+
+//-----------------------------------------------------------------------------
+// nsPipeEvents methods:
+//-----------------------------------------------------------------------------
+
+nsPipeEvents::~nsPipeEvents() {
+  // dispatch any pending events
+  for (auto& callback : mCallbacks) {
+    callback.Notify();
+  }
+  mCallbacks.Clear();
+}
+
+//-----------------------------------------------------------------------------
+// nsPipeInputStream methods:
+//-----------------------------------------------------------------------------
+
+NS_IMPL_ADDREF(nsPipeInputStream);
+NS_IMPL_RELEASE(nsPipeInputStream);
+
+NS_INTERFACE_TABLE_HEAD(nsPipeInputStream)
+  NS_INTERFACE_TABLE_BEGIN
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsIAsyncInputStream)
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsITellableStream)
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsISearchableInputStream)
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsICloneableInputStream)
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsIBufferedInputStream)
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsIClassInfo)
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsIInputStreamPriority)
+    NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(nsPipeInputStream, nsIInputStream,
+                                       nsIAsyncInputStream)
+    NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(nsPipeInputStream, nsISupports,
+                                       nsIAsyncInputStream)
+  NS_INTERFACE_TABLE_END
+NS_INTERFACE_TABLE_TAIL
+
+NS_IMPL_CI_INTERFACE_GETTER(nsPipeInputStream, nsIInputStream,
+                            nsIAsyncInputStream, nsITellableStream,
+                            nsISearchableInputStream, nsICloneableInputStream,
+                            nsIBufferedInputStream)
+
+NS_IMPL_THREADSAFE_CI(nsPipeInputStream)
+
+NS_IMETHODIMP
+nsPipeInputStream::Init(nsIInputStream*, uint32_t) {
+  MOZ_CRASH(
+      "nsPipeInputStream should never be initialized with "
+      "nsIBufferedInputStream::Init!\n");
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::GetData(nsIInputStream** aResult) {
+  // as this was not created with init() we are not
+  // wrapping anything
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+uint32_t nsPipeInputStream::Available() {
+  mPipe->mReentrantMonitor.AssertCurrentThreadIn();
+  return mReadState.mAvailable;
+}
+
+nsresult nsPipeInputStream::Wait() {
+  MOZ_DIAGNOSTIC_ASSERT(mBlocking);
+
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+  while (NS_SUCCEEDED(Status(mon)) && (mReadState.mAvailable == 0)) {
+    LOG(("III pipe input: waiting for data\n"));
+
+    mBlocked = true;
+    mon.Wait();
+    mBlocked = false;
+
+    LOG(("III pipe input: woke up [status=%" PRIx32 " available=%u]\n",
+         static_cast<uint32_t>(Status(mon)), mReadState.mAvailable));
+  }
+
+  return Status(mon) == NS_BASE_STREAM_CLOSED ? NS_OK : Status(mon);
+}
+
+MonitorAction nsPipeInputStream::OnInputReadable(
+    uint32_t aBytesWritten, nsPipeEvents& aEvents,
+    const ReentrantMonitorAutoEnter& ev) {
+  MonitorAction result = DoNotNotifyMonitor;
+
+  mPipe->mReentrantMonitor.AssertCurrentThreadIn();
+  mReadState.mAvailable += aBytesWritten;
+
+  if (mCallback && !(mCallback.Flags() & WAIT_CLOSURE_ONLY)) {
+    aEvents.NotifyReady(std::move(mCallback));
+  } else if (mBlocked) {
+    result = NotifyMonitor;
+  }
+
+  return result;
+}
+
+MonitorAction nsPipeInputStream::OnInputException(
+    nsresult aReason, nsPipeEvents& aEvents,
+    const ReentrantMonitorAutoEnter& ev) {
+  LOG(("nsPipeInputStream::OnInputException [this=%p reason=%" PRIx32 "]\n",
+       this, static_cast<uint32_t>(aReason)));
+
+  MonitorAction result = DoNotNotifyMonitor;
+
+  MOZ_DIAGNOSTIC_ASSERT(NS_FAILED(aReason));
+
+  if (NS_SUCCEEDED(mInputStatus)) {
+    mInputStatus = aReason;
+  }
+
+  // force count of available bytes to zero.
+  mPipe->DrainInputStream(mReadState, aEvents);
+
+  if (mCallback) {
+    aEvents.NotifyReady(std::move(mCallback));
+  } else if (mBlocked) {
+    result = NotifyMonitor;
+  }
+
+  return result;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::CloseWithStatus(nsresult aReason) {
+  LOG(("III CloseWithStatus [this=%p reason=%" PRIx32 "]\n", this,
+       static_cast<uint32_t>(aReason)));
+
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+  if (NS_FAILED(mInputStatus)) {
+    return NS_OK;
+  }
+
+  if (NS_SUCCEEDED(aReason)) {
+    aReason = NS_BASE_STREAM_CLOSED;
+  }
+
+  mPipe->OnInputStreamException(this, aReason);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::SetPriority(uint32_t priority) {
+  mPriority = priority;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::GetPriority(uint32_t* priority) {
+  *priority = mPriority;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::Close() { return CloseWithStatus(NS_BASE_STREAM_CLOSED); }
+
+NS_IMETHODIMP
+nsPipeInputStream::Available(uint64_t* aResult) {
+  // nsPipeInputStream supports under 4GB stream only
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+  // return error if closed
+  if (!mReadState.mAvailable && NS_FAILED(Status(mon))) {
+    return Status(mon);
+  }
+
+  *aResult = (uint64_t)mReadState.mAvailable;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::StreamStatus() {
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+  return mReadState.mAvailable ? NS_OK : Status(mon);
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                                uint32_t aCount, uint32_t* aReadCount) {
+  LOG(("III ReadSegments [this=%p count=%u]\n", this, aCount));
+
+  nsresult rv = NS_OK;
+
+  *aReadCount = 0;
+  while (aCount) {
+    AutoReadSegment segment(mPipe, mReadState, aCount);
+    rv = segment.Status();
+    if (NS_FAILED(rv)) {
+      // ignore this error if we've already read something.
+      if (*aReadCount > 0) {
+        rv = NS_OK;
+        break;
+      }
+      if (rv == NS_BASE_STREAM_WOULD_BLOCK) {
+        // pipe is empty
+        if (!mBlocking) {
+          break;
+        }
+        // wait for some data to be written to the pipe
+        rv = Wait();
+        if (NS_SUCCEEDED(rv)) {
+          continue;
+        }
+      }
+      // ignore this error, just return.
+      if (rv == NS_BASE_STREAM_CLOSED) {
+        rv = NS_OK;
+        break;
+      }
+      mPipe->OnInputStreamException(this, rv);
+      break;
+    }
+
+    uint32_t writeCount;
+    while (segment.Length()) {
+      writeCount = 0;
+
+      rv = aWriter(static_cast<nsIAsyncInputStream*>(this), aClosure,
+                   segment.Data(), *aReadCount, segment.Length(), &writeCount);
+
+      if (NS_FAILED(rv) || writeCount == 0) {
+        aCount = 0;
+        // any errors returned from the writer end here: do not
+        // propagate to the caller of ReadSegments.
+        rv = NS_OK;
+        break;
+      }
+
+      MOZ_DIAGNOSTIC_ASSERT(writeCount <= segment.Length());
+      segment.Advance(writeCount);
+      aCount -= writeCount;
+      *aReadCount += writeCount;
+      mLogicalOffset += writeCount;
+    }
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::Read(char* aToBuf, uint32_t aBufLen, uint32_t* aReadCount) {
+  return ReadSegments(NS_CopySegmentToBuffer, aToBuf, aBufLen, aReadCount);
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::IsNonBlocking(bool* aNonBlocking) {
+  *aNonBlocking = !mBlocking;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::AsyncWait(nsIInputStreamCallback* aCallback, uint32_t aFlags,
+                             uint32_t aRequestedCount,
+                             nsIEventTarget* aTarget) {
+  LOG(("III AsyncWait [this=%p]\n", this));
+
+  nsPipeEvents pipeEvents;
+  {
+    ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+    // replace a pending callback
+    mCallback = nullptr;
+
+    if (!aCallback) {
+      return NS_OK;
+    }
+
+    CallbackHolder callback(this, aCallback, aFlags, aTarget);
+
+    if (NS_FAILED(Status(mon)) ||
+        (mReadState.mAvailable && !(aFlags & WAIT_CLOSURE_ONLY))) {
+      // stream is already closed or readable; post event.
+      pipeEvents.NotifyReady(std::move(callback));
+    } else {
+      // queue up callback object to be notified when data becomes available
+      mCallback = std::move(callback);
+    }
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::Tell(int64_t* aOffset) {
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+  // return error if closed
+  if (!mReadState.mAvailable && NS_FAILED(Status(mon))) {
+    return Status(mon);
+  }
+
+  *aOffset = mLogicalOffset;
+  return NS_OK;
+}
+
+static bool strings_equal(bool aIgnoreCase, const char* aS1, const char* aS2,
+                          uint32_t aLen) {
+  return aIgnoreCase ? !nsCRT::strncasecmp(aS1, aS2, aLen)
+                     : !strncmp(aS1, aS2, aLen);
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::Search(const char* aForString, bool aIgnoreCase,
+                          bool* aFound, uint32_t* aOffsetSearchedTo) {
+  LOG(("III Search [for=%s ic=%u]\n", aForString, aIgnoreCase));
+
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+  char* cursor1;
+  char* limit1;
+  uint32_t index = 0, offset = 0;
+  uint32_t strLen = strlen(aForString);
+
+  mPipe->PeekSegment(mReadState, 0, cursor1, limit1);
+  if (cursor1 == limit1) {
+    *aFound = false;
+    *aOffsetSearchedTo = 0;
+    LOG(("  result [aFound=%u offset=%u]\n", *aFound, *aOffsetSearchedTo));
+    return NS_OK;
+  }
+
+  while (true) {
+    uint32_t i, len1 = limit1 - cursor1;
+
+    // check if the string is in the buffer segment
+    for (i = 0; i < len1 - strLen + 1; i++) {
+      if (strings_equal(aIgnoreCase, &cursor1[i], aForString, strLen)) {
+        *aFound = true;
+        *aOffsetSearchedTo = offset + i;
+        LOG(("  result [aFound=%u offset=%u]\n", *aFound, *aOffsetSearchedTo));
+        return NS_OK;
+      }
+    }
+
+    // get the next segment
+    char* cursor2;
+    char* limit2;
+    uint32_t len2;
+
+    index++;
+    offset += len1;
+
+    mPipe->PeekSegment(mReadState, index, cursor2, limit2);
+    if (cursor2 == limit2) {
+      *aFound = false;
+      *aOffsetSearchedTo = offset - strLen + 1;
+      LOG(("  result [aFound=%u offset=%u]\n", *aFound, *aOffsetSearchedTo));
+      return NS_OK;
+    }
+    len2 = limit2 - cursor2;
+
+    // check if the string is straddling the next buffer segment
+    uint32_t lim = XPCOM_MIN(strLen, len2 + 1);
+    for (i = 0; i < lim; ++i) {
+      uint32_t strPart1Len = strLen - i - 1;
+      uint32_t strPart2Len = strLen - strPart1Len;
+      const char* strPart2 = &aForString[strLen - strPart2Len];
+      uint32_t bufSeg1Offset = len1 - strPart1Len;
+      if (strings_equal(aIgnoreCase, &cursor1[bufSeg1Offset], aForString,
+                        strPart1Len) &&
+          strings_equal(aIgnoreCase, cursor2, strPart2, strPart2Len)) {
+        *aFound = true;
+        *aOffsetSearchedTo = offset - strPart1Len;
+        LOG(("  result [aFound=%u offset=%u]\n", *aFound, *aOffsetSearchedTo));
+        return NS_OK;
+      }
+    }
+
+    // finally continue with the next buffer
+    cursor1 = cursor2;
+    limit1 = limit2;
+  }
+
+  MOZ_ASSERT_UNREACHABLE("can't get here");
+  return NS_ERROR_UNEXPECTED;  // keep compiler happy
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::GetCloneable(bool* aCloneableOut) {
+  *aCloneableOut = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::Clone(nsIInputStream** aCloneOut) {
+  return mPipe->CloneInputStream(this, aCloneOut);
+}
+
+nsresult nsPipeInputStream::Status(const ReentrantMonitorAutoEnter& ev) const {
+  if (NS_FAILED(mInputStatus)) {
+    return mInputStatus;
+  }
+
+  if (mReadState.mAvailable) {
+    // Still something to read and this input stream state is OK.
+    return NS_OK;
+  }
+
+  // Nothing to read, just fall through to the pipe's state that
+  // may reflect state of its output stream side (already closed).
+  return mPipe->mStatus;
+}
+
+nsresult nsPipeInputStream::Status() const {
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+  return Status(mon);
+}
+
+nsPipeInputStream::~nsPipeInputStream() { Close(); }
+
+//-----------------------------------------------------------------------------
+// nsPipeOutputStream methods:
+//-----------------------------------------------------------------------------
+
+NS_IMPL_QUERY_INTERFACE(nsPipeOutputStream, nsIOutputStream,
+                        nsIAsyncOutputStream, nsIClassInfo)
+
+NS_IMPL_CI_INTERFACE_GETTER(nsPipeOutputStream, nsIOutputStream,
+                            nsIAsyncOutputStream)
+
+NS_IMPL_THREADSAFE_CI(nsPipeOutputStream)
+
+nsresult nsPipeOutputStream::Wait() {
+  MOZ_DIAGNOSTIC_ASSERT(mBlocking);
+
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+  if (NS_SUCCEEDED(mPipe->mStatus) && !mWritable) {
+    LOG(("OOO pipe output: waiting for space\n"));
+    mBlocked = true;
+    mon.Wait();
+    mBlocked = false;
+    LOG(("OOO pipe output: woke up [pipe-status=%" PRIx32 " writable=%u]\n",
+         static_cast<uint32_t>(mPipe->mStatus), mWritable));
+  }
+
+  return mPipe->mStatus == NS_BASE_STREAM_CLOSED ? NS_OK : mPipe->mStatus;
+}
+
+MonitorAction nsPipeOutputStream::OnOutputWritable(nsPipeEvents& aEvents) {
+  MonitorAction result = DoNotNotifyMonitor;
+
+  mWritable = true;
+
+  if (mCallback && !(mCallback.Flags() & WAIT_CLOSURE_ONLY)) {
+    aEvents.NotifyReady(std::move(mCallback));
+  } else if (mBlocked) {
+    result = NotifyMonitor;
+  }
+
+  return result;
+}
+
+MonitorAction nsPipeOutputStream::OnOutputException(nsresult aReason,
+                                                    nsPipeEvents& aEvents) {
+  LOG(("nsPipeOutputStream::OnOutputException [this=%p reason=%" PRIx32 "]\n",
+       this, static_cast<uint32_t>(aReason)));
+
+  MonitorAction result = DoNotNotifyMonitor;
+
+  MOZ_DIAGNOSTIC_ASSERT(NS_FAILED(aReason));
+  mWritable = false;
+
+  if (mCallback) {
+    aEvents.NotifyReady(std::move(mCallback));
+  } else if (mBlocked) {
+    result = NotifyMonitor;
+  }
+
+  return result;
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsPipeOutputStream::AddRef() {
+  ++mWriterRefCnt;
+  return mPipe->AddRef();
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsPipeOutputStream::Release() {
+  if (--mWriterRefCnt == 0) {
+    Close();
+  }
+  return mPipe->Release();
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::CloseWithStatus(nsresult aReason) {
+  LOG(("OOO CloseWithStatus [this=%p reason=%" PRIx32 "]\n", this,
+       static_cast<uint32_t>(aReason)));
+
+  if (NS_SUCCEEDED(aReason)) {
+    aReason = NS_BASE_STREAM_CLOSED;
+  }
+
+  // input stream may remain open
+  mPipe->OnPipeException(aReason, true);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::Close() { return CloseWithStatus(NS_BASE_STREAM_CLOSED); }
+
+NS_IMETHODIMP
+nsPipeOutputStream::WriteSegments(nsReadSegmentFun aReader, void* aClosure,
+                                  uint32_t aCount, uint32_t* aWriteCount) {
+  LOG(("OOO WriteSegments [this=%p count=%u]\n", this, aCount));
+
+  nsresult rv = NS_OK;
+
+  char* segment;
+  uint32_t segmentLen;
+
+  *aWriteCount = 0;
+  while (aCount) {
+    rv = mPipe->GetWriteSegment(segment, segmentLen);
+    if (NS_FAILED(rv)) {
+      if (rv == NS_BASE_STREAM_WOULD_BLOCK) {
+        // pipe is full
+        if (!mBlocking) {
+          // ignore this error if we've already written something
+          if (*aWriteCount > 0) {
+            rv = NS_OK;
+          }
+          break;
+        }
+        // wait for the pipe to have an empty segment.
+        rv = Wait();
+        if (NS_SUCCEEDED(rv)) {
+          continue;
+        }
+      }
+      mPipe->OnPipeException(rv);
+      break;
+    }
+
+    // write no more than aCount
+    if (segmentLen > aCount) {
+      segmentLen = aCount;
+    }
+
+    uint32_t readCount, originalLen = segmentLen;
+    while (segmentLen) {
+      readCount = 0;
+
+      rv = aReader(this, aClosure, segment, *aWriteCount, segmentLen,
+                   &readCount);
+
+      if (NS_FAILED(rv) || readCount == 0) {
+        aCount = 0;
+        // any errors returned from the aReader end here: do not
+        // propagate to the caller of WriteSegments.
+        rv = NS_OK;
+        break;
+      }
+
+      MOZ_DIAGNOSTIC_ASSERT(readCount <= segmentLen);
+      segment += readCount;
+      segmentLen -= readCount;
+      aCount -= readCount;
+      *aWriteCount += readCount;
+      mLogicalOffset += readCount;
+    }
+
+    if (segmentLen < originalLen) {
+      mPipe->AdvanceWriteCursor(originalLen - segmentLen);
+    }
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::Write(const char* aFromBuf, uint32_t aBufLen,
+                          uint32_t* aWriteCount) {
+  return WriteSegments(NS_CopyBufferToSegment, (void*)aFromBuf, aBufLen,
+                       aWriteCount);
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::Flush() {
+  // nothing to do
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::StreamStatus() {
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+  return mPipe->mStatus;
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::WriteFrom(nsIInputStream* aFromStream, uint32_t aCount,
+                              uint32_t* aWriteCount) {
+  return WriteSegments(NS_CopyStreamToSegment, aFromStream, aCount,
+                       aWriteCount);
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::IsNonBlocking(bool* aNonBlocking) {
+  *aNonBlocking = !mBlocking;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::AsyncWait(nsIOutputStreamCallback* aCallback,
+                              uint32_t aFlags, uint32_t aRequestedCount,
+                              nsIEventTarget* aTarget) {
+  LOG(("OOO AsyncWait [this=%p]\n", this));
+
+  nsPipeEvents pipeEvents;
+  {
+    ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+    // replace a pending callback
+    mCallback = nullptr;
+
+    if (!aCallback) {
+      return NS_OK;
+    }
+
+    CallbackHolder callback(this, aCallback, aFlags, aTarget);
+
+    if (NS_FAILED(mPipe->mStatus) ||
+        (mWritable && !(aFlags & WAIT_CLOSURE_ONLY))) {
+      // stream is already closed or writable; post event.
+      pipeEvents.NotifyReady(std::move(callback));
+    } else {
+      // queue up callback object to be notified when data becomes available
+      mCallback = std::move(callback);
+    }
+  }
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+void NS_NewPipe(nsIInputStream** aPipeIn, nsIOutputStream** aPipeOut,
+                uint32_t aSegmentSize, uint32_t aMaxSize,
+                bool aNonBlockingInput, bool aNonBlockingOutput) {
+  if (aSegmentSize == 0) {
+    aSegmentSize = DEFAULT_SEGMENT_SIZE;
+  }
+
+  // Handle aMaxSize of UINT32_MAX as a special case
+  uint32_t segmentCount;
+  if (aMaxSize == UINT32_MAX) {
+    segmentCount = UINT32_MAX;
+  } else {
+    segmentCount = aMaxSize / aSegmentSize;
+  }
+
+  nsIAsyncInputStream* in;
+  nsIAsyncOutputStream* out;
+  NS_NewPipe2(&in, &out, aNonBlockingInput, aNonBlockingOutput, aSegmentSize,
+              segmentCount);
+
+  *aPipeIn = in;
+  *aPipeOut = out;
+}
+
+// Disable thread safety analysis as this is logically a constructor, and no
+// additional threads can observe these objects yet.
+void NS_NewPipe2(nsIAsyncInputStream** aPipeIn, nsIAsyncOutputStream** aPipeOut,
+                 bool aNonBlockingInput, bool aNonBlockingOutput,
+                 uint32_t aSegmentSize,
+                 uint32_t aSegmentCount) MOZ_NO_THREAD_SAFETY_ANALYSIS {
+  RefPtr<nsPipe> pipe =
+      new nsPipe(aSegmentSize ? aSegmentSize : DEFAULT_SEGMENT_SIZE,
+                 aSegmentCount ? aSegmentCount : DEFAULT_SEGMENT_COUNT);
+
+  RefPtr<nsPipeInputStream> pipeIn = new nsPipeInputStream(pipe);
+  pipe->mInputList.AppendElement(pipeIn);
+  RefPtr<nsPipeOutputStream> pipeOut = &pipe->mOutput;
+
+  pipeIn->SetNonBlocking(aNonBlockingInput);
+  pipeOut->SetNonBlocking(aNonBlockingOutput);
+
+  pipeIn.forget(aPipeIn);
+  pipeOut.forget(aPipeOut);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+// Thin nsIPipe implementation for consumers of the component manager interface
+// for creating pipes. Acts as a thin wrapper around NS_NewPipe2 for JS callers.
+class nsPipeHolder final : public nsIPipe {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIPIPE
+
+ private:
+  ~nsPipeHolder() = default;
+
+  nsCOMPtr<nsIAsyncInputStream> mInput;
+  nsCOMPtr<nsIAsyncOutputStream> mOutput;
+};
+
+NS_IMPL_ISUPPORTS(nsPipeHolder, nsIPipe)
+
+NS_IMETHODIMP
+nsPipeHolder::Init(bool aNonBlockingInput, bool aNonBlockingOutput,
+                   uint32_t aSegmentSize, uint32_t aSegmentCount) {
+  if (mInput || mOutput) {
+    return NS_ERROR_ALREADY_INITIALIZED;
+  }
+  NS_NewPipe2(getter_AddRefs(mInput), getter_AddRefs(mOutput),
+              aNonBlockingInput, aNonBlockingOutput, aSegmentSize,
+              aSegmentCount);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeHolder::GetInputStream(nsIAsyncInputStream** aInputStream) {
+  if (mInput) {
+    *aInputStream = do_AddRef(mInput).take();
+    return NS_OK;
+  }
+  return NS_ERROR_NOT_INITIALIZED;
+}
+
+NS_IMETHODIMP
+nsPipeHolder::GetOutputStream(nsIAsyncOutputStream** aOutputStream) {
+  if (mOutput) {
+    *aOutputStream = do_AddRef(mOutput).take();
+    return NS_OK;
+  }
+  return NS_ERROR_NOT_INITIALIZED;
+}
+
+nsresult nsPipeConstructor(REFNSIID aIID, void** aResult) {
+  RefPtr<nsPipeHolder> pipe = new nsPipeHolder();
+  nsresult rv = pipe->QueryInterface(aIID, aResult);
+  return rv;
+}
+
+////////////////////////////////////////////////////////////////////////////////