SlicedInputStream.h

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/* -*- 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/. */

#ifndef SlicedInputStream_h

#define SlicedInputStream_h

#include "mozilla/Attributes.h"

#include "mozilla/Mutex.h"

#include "nsCOMPtr.h"

#include "nsIAsyncInputStream.h"

#include "nsICloneableInputStream.h"

#include "nsIIPCSerializableInputStream.h"

#include "nsISeekableStream.h"

#include "nsIInputStreamLength.h"

namespace mozilla {

// A wrapper for a slice of an underlying input stream.

class SlicedInputStream final : public nsIAsyncInputStream,

                                public nsICloneableInputStream,

                                public nsIIPCSerializableInputStream,

                                public nsISeekableStream,

                                public nsIInputStreamCallback,

                                public nsIInputStreamLength,

                                public nsIAsyncInputStreamLength,

                                public nsIInputStreamLengthCallback {

 public:

  NS_DECL_THREADSAFE_ISUPPORTS

  NS_DECL_NSIINPUTSTREAM

  NS_DECL_NSIASYNCINPUTSTREAM

  NS_DECL_NSICLONEABLEINPUTSTREAM

  NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM

  NS_DECL_NSISEEKABLESTREAM

  NS_DECL_NSITELLABLESTREAM

  NS_DECL_NSIINPUTSTREAMCALLBACK

  NS_DECL_NSIINPUTSTREAMLENGTH

  NS_DECL_NSIASYNCINPUTSTREAMLENGTH

  NS_DECL_NSIINPUTSTREAMLENGTHCALLBACK

  // Create an input stream whose data comes from a slice of aInputStream.  The

  // slice begins at aStart bytes beyond aInputStream's current position, and

  // extends for a maximum of aLength bytes.  If aInputStream contains fewer

  // than aStart bytes, reading from SlicedInputStream returns no data.  If

  // aInputStream contains more than aStart bytes, but fewer than aStart +

  // aLength bytes, reading from SlicedInputStream returns as many bytes as can

  // be consumed from aInputStream after reading aLength bytes.

//

  // aInputStream should not be read from after constructing a

  // SlicedInputStream wrapper around it.

  SlicedInputStream(already_AddRefed<nsIInputStream> aInputStream,

                    uint64_t aStart, uint64_t aLength);

  // This CTOR is meant to be used just for IPC.

  SlicedInputStream();

 private:

  ~SlicedInputStream();

  void SetSourceStream(already_AddRefed<nsIInputStream> aInputStream);

  uint64_t AdjustRange(uint64_t aRange);

  nsCOMPtr<nsIInputStream> mInputStream;

  // Raw pointers because these are just QI of mInputStream.

  nsICloneableInputStream* mWeakCloneableInputStream;

  nsIIPCSerializableInputStream* mWeakIPCSerializableInputStream;

  nsISeekableStream* mWeakSeekableInputStream;

  nsITellableStream* mWeakTellableInputStream;

  nsIAsyncInputStream* mWeakAsyncInputStream;

  nsIInputStreamLength* mWeakInputStreamLength;

  nsIAsyncInputStreamLength* mWeakAsyncInputStreamLength;

  uint64_t mStart;

  uint64_t mLength;

  uint64_t mCurPos;

  bool mClosed;

  // These four are used for AsyncWait. They are protected by mutex because

  // touched on multiple threads.

  nsCOMPtr<nsIInputStreamCallback> mAsyncWaitCallback MOZ_GUARDED_BY(mMutex);

  nsCOMPtr<nsIEventTarget> mAsyncWaitEventTarget MOZ_GUARDED_BY(mMutex);

  uint32_t mAsyncWaitFlags MOZ_GUARDED_BY(mMutex);

  uint32_t mAsyncWaitRequestedCount MOZ_GUARDED_BY(mMutex);

  // This is use for nsIAsyncInputStreamLength::AsyncWait.

  // This is protected by mutex.

  nsCOMPtr<nsIInputStreamLengthCallback> mAsyncWaitLengthCallback

      MOZ_GUARDED_BY(mMutex);

  Mutex mMutex;

};

}  // namespace mozilla

#endif  // SlicedInputStream_h