core/fxcrt/cfx_readonlymemorystream.cpp

// Copyright 2018 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com

#include "core/fxcrt/cfx_readonlymemorystream.h"

#include "core/fxcrt/fx_safe_types.h"

CFX_ReadOnlyMemoryStream::CFX_ReadOnlyMemoryStream(const uint8_t* pBuf,
                                                   FX_FILESIZE size)
    : m_pBuf(pBuf), m_size(size) {}

CFX_ReadOnlyMemoryStream::~CFX_ReadOnlyMemoryStream() = default;

FX_FILESIZE CFX_ReadOnlyMemoryStream::GetSize() {
  return m_size;
}

bool CFX_ReadOnlyMemoryStream::ReadBlock(void* buffer,
                                         FX_FILESIZE offset,
                                         size_t size) {
  if (offset < 0)
    return false;

  FX_SAFE_FILESIZE newPos = pdfium::base::checked_cast<FX_FILESIZE>(size);
  newPos += offset;
  if (!newPos.IsValid() || newPos.ValueOrDie() > m_size)
    return false;

  memcpy(buffer, m_pBuf + offset, size);
  return true;
}