xpcom/io/SlicedInputStream.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef SlicedInputStream_h
   8 #define SlicedInputStream_h
   9
  10 #include "mozilla/Attributes.h"
  11 #include "mozilla/Mutex.h"
  12 #include "nsCOMPtr.h"
  13 #include "nsIAsyncInputStream.h"
  14 #include "nsICloneableInputStream.h"
  15 #include "nsIIPCSerializableInputStream.h"
  16 #include "nsISeekableStream.h"
  17 #include "nsIInputStreamLength.h"
  18
  19 namespace mozilla {
  20
  21 // A wrapper for a slice of an underlying input stream.
  22
  23 class SlicedInputStream final : public nsIAsyncInputStream,
  24                                 public nsICloneableInputStream,
  25                                 public nsIIPCSerializableInputStream,
  26                                 public nsISeekableStream,
  27                                 public nsIInputStreamCallback,
  28                                 public nsIInputStreamLength,
  29                                 public nsIAsyncInputStreamLength,
  30                                 public nsIInputStreamLengthCallback {
  31  public:
  32   NS_DECL_THREADSAFE_ISUPPORTS
  33   NS_DECL_NSIINPUTSTREAM
  34   NS_DECL_NSIASYNCINPUTSTREAM
  35   NS_DECL_NSICLONEABLEINPUTSTREAM
  36   NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM
  37   NS_DECL_NSISEEKABLESTREAM
  38   NS_DECL_NSITELLABLESTREAM
  39   NS_DECL_NSIINPUTSTREAMCALLBACK
  40   NS_DECL_NSIINPUTSTREAMLENGTH
  41   NS_DECL_NSIASYNCINPUTSTREAMLENGTH
  42   NS_DECL_NSIINPUTSTREAMLENGTHCALLBACK
  43
  44   // Create an input stream whose data comes from a slice of aInputStream.  The
  45   // slice begins at aStart bytes beyond aInputStream's current position, and
  46   // extends for a maximum of aLength bytes.  If aInputStream contains fewer
  47   // than aStart bytes, reading from SlicedInputStream returns no data.  If
  48   // aInputStream contains more than aStart bytes, but fewer than aStart +
  49   // aLength bytes, reading from SlicedInputStream returns as many bytes as can
  50   // be consumed from aInputStream after reading aLength bytes.
  51   //
  52   // aInputStream should not be read from after constructing a
  53   // SlicedInputStream wrapper around it.
  54
  55   SlicedInputStream(already_AddRefed<nsIInputStream> aInputStream,
  56                     uint64_t aStart, uint64_t aLength);
  57
  58   // This CTOR is meant to be used just for IPC.
  59   SlicedInputStream();
  60
  61  private:
  62   ~SlicedInputStream();
  63
  64   void SetSourceStream(already_AddRefed<nsIInputStream> aInputStream);
  65
  66   uint64_t AdjustRange(uint64_t aRange);
  67
  68   nsCOMPtr<nsIInputStream> mInputStream;
  69
  70   // Raw pointers because these are just QI of mInputStream.
  71   nsICloneableInputStream* mWeakCloneableInputStream;
  72   nsIIPCSerializableInputStream* mWeakIPCSerializableInputStream;
  73   nsISeekableStream* mWeakSeekableInputStream;
  74   nsITellableStream* mWeakTellableInputStream;
  75   nsIAsyncInputStream* mWeakAsyncInputStream;
  76   nsIInputStreamLength* mWeakInputStreamLength;
  77   nsIAsyncInputStreamLength* mWeakAsyncInputStreamLength;
  78
  79   uint64_t mStart;
  80   uint64_t mLength;
  81   uint64_t mCurPos;
  82
  83   bool mClosed;
  84
  85   // These four are used for AsyncWait. They are protected by mutex because
  86   // touched on multiple threads.
  87   nsCOMPtr<nsIInputStreamCallback> mAsyncWaitCallback MOZ_GUARDED_BY(mMutex);
  88   nsCOMPtr<nsIEventTarget> mAsyncWaitEventTarget MOZ_GUARDED_BY(mMutex);
  89   uint32_t mAsyncWaitFlags MOZ_GUARDED_BY(mMutex);
  90   uint32_t mAsyncWaitRequestedCount MOZ_GUARDED_BY(mMutex);
  91
  92   // This is use for nsIAsyncInputStreamLength::AsyncWait.
  93   // This is protected by mutex.
  94   nsCOMPtr<nsIInputStreamLengthCallback> mAsyncWaitLengthCallback
  95       MOZ_GUARDED_BY(mMutex);
  96
  97   Mutex mMutex;
  98 };
  99
 100 }  // namespace mozilla
 101
 102 #endif  // SlicedInputStream_h