Frank Chang

cMemoryMappedFile::cMemoryMappedFile(long FileSize_, OpenModes OpenMode_,AccessModes AccessMode_,
		ShareModes ShareMode_,long Flags_,void *Security_,FILEHANDLE Template_) {
         FileSize = FileSize_;
	char buffer[BUFFER_SIZE];
	#if defined(__windows)
	   DWORD dwRetVal = 0;
	   UINT uRetVal   = 0;
            DWORD dwPtr    = 0;
	   BOOL isSetEndOfFile = FALSE;
            LARGE_INTEGER Distance_;
	   DWORD ErrorCode = 0;

	   char lpTempPathBuffer[MAX_PATH];


	   //  Gets the temp path env string (no guarantee it's a valid path).
	   dwRetVal = GetTempPath(MAX_PATH,          // length of the buffer
                           lpTempPathBuffer); // buffer for path
	   if (dwRetVal > MAX_PATH || (dwRetVal == 0))
	      throw cException(ERR_MEMORYMAPPING,"");
	   }

            //  Generates a temporary file name.
            uRetVal = GetTempFileName(lpTempPathBuffer, // directory for tmp files
                              TEXT("DEMO"),     // temp file name prefix
                              0,                // create unique name
                              TempFileName);  // buffer for name
            if (uRetVal == 0)
            {

	      throw cException(ERR_MEMORYMAPPING,lpTempPathBuffer);
            }
            //  Creates the new file to write to for the upper-case version.
            hFile = CreateFile((LPTSTR) TempFileName, // file name
                            AccessMode_,        // open for write
                            0,                    // do not share
                            (SECURITY_ATTRIBUTES *) Security_,                 // default security
                            OpenMode_, // CREATE_ALWAYS,        // overwrite existing
                            Flags_,// normal file
                            Template_);                // no template
            if (hFile == INVALID_HANDLE_VALUE)
            {
               throw cException(ERR_MEMORYMAPPING,TempFileName);
            }
            Distance_.LowPart = (ULONG)FileSize_;
            Distance_.HighPart = 0;
            dwPtr = ::SetFilePointer(hFile,Distance_.LowPart,
   		                   &(Distance_.HighPart), FileBegin);

            if (dwPtr == INVALID_SET_FILE_POINTER){
               throw cException(ERR_MEMORYMAPPING,TempFileName);
            }
            isSetEndOfFile = SetEndOfFile(hFile);
            if (!isSetEndOfFile){
              ErrorCode = GetLastError();
              throw cException(ERR_MEMORYMAPPING,TempFileName);
            }
            hMapping=::CreateFileMapping(hFile,(SECURITY_ATTRIBUTES*)Security_,PAGE_READWRITE,0,0,0);
            if (hMapping==NULL)
               throw cException(ERR_MEMORYMAPPING,TempFileName);
            MapPtr = (void*)::MapViewOfFile( hMapping, FILE_MAP_WRITE | FILE_MAP_READ,0,0,FileSize);
            if (MapPtr==NULL){
	       ErrorCode = GetLastError();
	       throw cException(ERR_MEMORYMAPPING,TempFileName);
            }
        #elif defined(__unix)
           int oflag = 0;
	  strcpy(TempFileName,"/var/tmp/pdn-XXXXXXX");
	  if ((hFile=mkstemp(TempFileName)) < 0){
	     perror("generating temp filename");
	     throw cException(ERR_MEMORYMAPPING,TempFileName);
	  }
	  FileSize = FileSize_;
	  // To do this on UNIX, seek to (RequiredFileSize - 1) and then write a byte.
	  // The value of the byte can be anything, but zero is the obvious choice
	  if (lseek(hFile,FileSize_-1,0) == -1){
		perror("lseek");
		throw cException(ERR_MEMORYMAPPING,TempFileName);
	  }
           memset(buffer,'\x0',BUFFER_SIZE);
	  if (write(hFile,buffer,1) == -1){
		perror("write");
		throw cException(ERR_MEMORYMAPPING,TempFileName);
	  }
           MapPtr = (void *)mmap(NULL, FileSize, PROT_READ | PROT_WRITE, MAP_SHARED, hFile, 0);
	  if (MapPtr==NULL)
		throw cException(ERR_MEMORYMAPPING,TempFileName);
        #endif
        FilePath=new char[strlen(TempFileName)+1];
        strcpy(FilePath,TempFileName);
    }