OW_TempFileEnumerationImplBase.cpp

Go to the documentation of this file.

/*******************************************************************************
* Copyright (C) 2001-2004 Vintela, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
*  - Redistributions of source code must retain the above copyright notice,
*    this list of conditions and the following disclaimer.
*
*  - Redistributions in binary form must reproduce the above copyright notice,
*    this list of conditions and the following disclaimer in the documentation
*    and/or other materials provided with the distribution.
*
*  - Neither the name of Vintela, Inc. nor the names of its
*    contributors may be used to endorse or promote products derived from this
*    software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL Vintela, Inc. OR THE CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*******************************************************************************/

#include "OW_config.h"
#include "OW_TempFileEnumerationImplBase.hpp"
#include "OW_EnumerationException.hpp"
#include "OW_File.hpp"
#include "OW_FileSystem.hpp"

namespace OW_NAMESPACE
{

namespace
{
const UInt32 TEMPFILE_ENUMERATION_SIG = 0x4f57454e; // "OWEN"
}

TempFileEnumerationImplBase::TempFileEnumerationImplBase()
   : m_size(0), m_Data()
{
   UInt32 enumSig = TEMPFILE_ENUMERATION_SIG;
   m_Data.write(reinterpret_cast<const char*>(&enumSig), sizeof(enumSig));
   if (!m_Data.good())
   {
      OW_THROW(EnumerationException, "Failed to write signature to "
         "enumeration tempfile.");
   }
   // now we have to read the sig so that the temp file stream is
   // positioned correctly
   UInt32 tmpSig;
   m_Data.read(reinterpret_cast<char*>(&tmpSig), sizeof(tmpSig));
   if (!m_Data.good())
   {
      OW_THROW(EnumerationException, "Failed to read signature from "
         "enumeration tempfile.");
   }
}

TempFileEnumerationImplBase::TempFileEnumerationImplBase(String const& filename)
   : m_size(readSize(filename)), m_Data(filename)
{
   // now we have to read the sig so that the temp file stream is
   // positioned correctly
   UInt32 tmpSig;
   m_Data.read(reinterpret_cast<char*>(&tmpSig), sizeof(tmpSig));
   if (!m_Data.good())
   {
      OW_THROW(EnumerationException, "Failed to read signature of "
         "enumeration tempfile.");
   }
   if (tmpSig != TEMPFILE_ENUMERATION_SIG)
   {
      OW_THROW(EnumerationException, "Signature of enumeration tempfile is not valid.");
   }
}
TempFileEnumerationImplBase::~TempFileEnumerationImplBase()
{
}
bool
TempFileEnumerationImplBase::hasMoreElements() const
{
   
   return m_size > 0;
}
size_t
TempFileEnumerationImplBase::numberOfElements() const
{
   return m_size;
}
void
TempFileEnumerationImplBase::clear()
{
   m_size = 0;
   m_Data.reset();
}
String
TempFileEnumerationImplBase::releaseFile()
{
   // Append the size onto the end of the stream so we can recover it
   // when constructing from the file
   m_Data.write(reinterpret_cast<char*>(&m_size), sizeof(m_size));
   if (!m_Data.good())
   {
      OW_THROW(EnumerationException, "Failed to write size to "
         "enumeration tempfile.");
   }
   String rval = m_Data.releaseFile();
   clear();
   return rval;
}

bool
TempFileEnumerationImplBase::usingTempFile() const
{
   return m_Data.usingTempFile();
}

size_t 
TempFileEnumerationImplBase::readSize(String const& filename)
{
   size_t size;
   // open the file and read the size that is written to the end of it.
   File f = FileSystem::openFile(filename);
   if (!f)
   {
      OW_THROW(EnumerationException, "Failed to open file");
   }
   
   // Check that the correct signature is on the file
   UInt32 fileSig;
   if (f.read(reinterpret_cast<char*>(&fileSig), sizeof(fileSig)) != sizeof(fileSig))
   {
      OW_THROW(EnumerationException, "Failure to read enumeration "
         "signature");
   }
   if (fileSig != TEMPFILE_ENUMERATION_SIG)
   {
      OW_THROW(EnumerationException, "Attempted to construct an "
         "enumeration from a file that does not have the correct "
         "signature");
   }
   
   off_t whence = f.seek(-static_cast<off_t>(sizeof(size)), SEEK_END);
   if (whence == -1)
   {
      OW_THROW(EnumerationException, "Failure to seek");
   }
   if (f.read(reinterpret_cast<char*>(&size), sizeof(size), whence) != sizeof(size))
   {
      OW_THROW(EnumerationException, "Failure to read enumeration "
         "size");
   }
   if (f.close() == -1)
   {
      OW_THROW(EnumerationException, "Failure to close enumeration "
         "file");
   }
   return size;
}

void
TempFileEnumerationImplBase::throwIfEmpty() const
{
   if (!hasMoreElements())
   {
      OW_THROW (EnumerationException, "Attempt to Extract from empty Enum");
   }
}


} // end namespace OW_NAMESPACE

---