toolkit/recordreplay/BufferStream.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 file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_recordreplay_BufferStream_h
   8 #define mozilla_recordreplay_BufferStream_h
   9
  10 #include "InfallibleVector.h"
  11
  12 namespace mozilla {
  13 namespace recordreplay {
  14
  15 // BufferStream provides similar functionality to Stream in File.h, allowing
  16 // reading or writing to a stream of data backed by an in memory buffer instead
  17 // of data stored on disk.
  18 class BufferStream {
  19   InfallibleVector<char>* mOutput;
  20
  21   const char* mInput;
  22   size_t mInputSize;
  23
  24  public:
  25   BufferStream(const char* aInput, size_t aInputSize)
  26       : mOutput(nullptr), mInput(aInput), mInputSize(aInputSize) {}
  27
  28   explicit BufferStream(InfallibleVector<char>* aOutput)
  29       : mOutput(aOutput), mInput(nullptr), mInputSize(0) {}
  30
  31   void WriteBytes(const void* aData, size_t aSize) {
  32     MOZ_RELEASE_ASSERT(mOutput);
  33     mOutput->append((char*)aData, aSize);
  34   }
  35
  36   void WriteScalar(size_t aValue) { WriteBytes(&aValue, sizeof(aValue)); }
  37
  38   void ReadBytes(void* aData, size_t aSize) {
  39     if (aSize) {
  40       MOZ_RELEASE_ASSERT(mInput);
  41       MOZ_RELEASE_ASSERT(aSize <= mInputSize);
  42       memcpy(aData, mInput, aSize);
  43       mInput += aSize;
  44       mInputSize -= aSize;
  45     }
  46   }
  47
  48   size_t ReadScalar() {
  49     size_t rv;
  50     ReadBytes(&rv, sizeof(rv));
  51     return rv;
  52   }
  53
  54   bool IsEmpty() {
  55     MOZ_RELEASE_ASSERT(mInput);
  56     return mInputSize == 0;
  57   }
  58 };
  59
  60 }  // namespace recordreplay
  61 }  // namespace mozilla
  62
  63 #endif  // mozilla_recordreplay_BufferStream_h