cpdfsdk_customaccess.cpp

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// Copyright 2018 The PDFium Authors
// 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 "fpdfsdk/cpdfsdk_customaccess.h"
 
#include "core/fxcrt/fx_safe_types.h"
#include "core/fxcrt/numerics/safe_conversions.h"
 
CPDFSDK_CustomAccess::CPDFSDK_CustomAccess(FPDF_FILEACCESS* pFileAccess)
    : m_FileAccess(*pFileAccess) {}
 
CPDFSDK_CustomAccess::~CPDFSDK_CustomAccess() = default;
 
FX_FILESIZE CPDFSDK_CustomAccess::GetSize() {
  return m_FileAccess.m_FileLen;
}
 
bool CPDFSDK_CustomAccess::ReadBlockAtOffset(pdfium::span<uint8_t> buffer,
                                             FX_FILESIZE offset) {
  if (buffer.empty() || offset < 0)
    return false;
 
  if (!pdfium::IsValueInRangeForNumericType<FX_FILESIZE>(buffer.size())) {
    return false;
  }
 
  FX_SAFE_FILESIZE new_pos = buffer.size();
  new_pos += offset;
  return new_pos.IsValid() && new_pos.ValueOrDie() <= GetSize() &&
         m_FileAccess.m_GetBlock(
             m_FileAccess.m_Param, pdfium::checked_cast<unsigned long>(offset),
             buffer.data(), pdfium::checked_cast<unsigned long>(buffer.size()));
}