OWBI1_TempFileEnumerationImplBase.cpp

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#include "OWBI1_config.h"
#include "OWBI1_TempFileEnumerationImplBase.hpp"
#include "OWBI1_EnumerationException.hpp"
#include "OW_File.hpp"
#include "OW_FileSystem.hpp"
#include "OWBI1_Types.hpp"
#include "OW_TempFileStream.hpp"
#include "OWBI1_String.hpp"

namespace OWBI1
{
using namespace OpenWBEM;

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

TempFileEnumerationImplBase::TempFileEnumerationImplBase()
   : m_size(0), m_data(new OpenWBEM::TempFileStream())
{
   UInt32 enumSig = TEMPFILE_ENUMERATION_SIG;
   m_data->write(reinterpret_cast<const char*>(&enumSig), sizeof(enumSig));
   if (!m_data->good())
   {
      OWBI1_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())
   {
      OWBI1_THROW(EnumerationException, "Failed to read signature from "
         "enumeration tempfile.");
   }
}

TempFileEnumerationImplBase::TempFileEnumerationImplBase(String const& filename)
   : m_size(readSize(filename)), m_data(new OpenWBEM::TempFileStream(filename.c_str()))
{
   // 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())
   {
      OWBI1_THROW(EnumerationException, "Failed to read signature of "
         "enumeration tempfile.");
   }
   if (tmpSig != TEMPFILE_ENUMERATION_SIG)
   {
      OWBI1_THROW(EnumerationException, "Signature of enumeration tempfile is not valid.");
   }
}
TempFileEnumerationImplBase::~TempFileEnumerationImplBase()
{
   delete m_data;
}
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())
   {
      OWBI1_THROW(EnumerationException, "Failed to write size to "
         "enumeration tempfile.");
   }
   String rval = m_data->releaseFile().c_str();
   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.c_str());
   if (!f)
   {
      OWBI1_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))
   {
      OWBI1_THROW(EnumerationException, "Failure to read enumeration "
         "signature");
   }
   if (fileSig != TEMPFILE_ENUMERATION_SIG)
   {
      OWBI1_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)
   {
      OWBI1_THROW(EnumerationException, "Failure to seek");
   }
   if (f.read(reinterpret_cast<char*>(&size), sizeof(size), whence) != sizeof(size))
   {
      OWBI1_THROW(EnumerationException, "Failure to read enumeration "
         "size");
   }
   if (f.close() == -1)
   {
      OWBI1_THROW(EnumerationException, "Failure to close enumeration "
         "file");
   }
   return size;
}

void
TempFileEnumerationImplBase::throwIfEmpty() const
{
   if (!hasMoreElements())
   {
      OWBI1_THROW (EnumerationException, "Attempt to Extract from empty Enum");
   }
}


} // end namespace OWBI1

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