TempFileEnumerationImplBase.cpp

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#include "blocxx/BLOCXX_config.h"
#include "blocxx/TempFileEnumerationImplBase.hpp"
#include "blocxx/EnumerationException.hpp"
#include "blocxx/File.hpp"
#include "blocxx/FileSystem.hpp"
 
namespace BLOCXX_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())
   {
      BLOCXX_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())
   {
      BLOCXX_THROW(EnumerationException, "Failed to read signature from "
         "enumeration tempfile.");
   }
}
 
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();
}
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)
   {
      BLOCXX_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))
   {
      BLOCXX_THROW(EnumerationException, "Failure to read enumeration "
         "signature");
   }
   if (fileSig != TEMPFILE_ENUMERATION_SIG)
   {
      BLOCXX_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)
   {
      BLOCXX_THROW(EnumerationException, "Failure to seek");
   }
   if (f.read(reinterpret_cast<char*>(&size), sizeof(size), whence) != sizeof(size))
   {
      BLOCXX_THROW(EnumerationException, "Failure to read enumeration "
         "size");
   }
   if (f.close() == -1)
   {
      BLOCXX_THROW(EnumerationException, "Failure to close enumeration "
         "file");
   }
   return size;
}
 
void
TempFileEnumerationImplBase::throwIfEmpty() const
{
   if (!hasMoreElements())
   {
      BLOCXX_THROW (EnumerationException, "Attempt to Extract from empty Enum");
   }
}
 
 
} // end namespace BLOCXX_NAMESPACE