psf_open_handle (PSF_FILE * pfile)
{	DWORD dwDesiredAccess ;
	DWORD dwShareMode ;
	DWORD dwCreationDistribution ;
	HANDLE handle ;

	switch (pfile->mode)
	{	case SFM_READ :
				dwDesiredAccess = GENERIC_READ ;
				dwShareMode = FILE_SHARE_READ | FILE_SHARE_WRITE ;
				dwCreationDistribution = OPEN_EXISTING ;
				break ;

		case SFM_WRITE :
				dwDesiredAccess = GENERIC_WRITE ;
				dwShareMode = FILE_SHARE_READ | FILE_SHARE_WRITE ;
				dwCreationDistribution = CREATE_ALWAYS ;
				break ;

		case SFM_RDWR :
				dwDesiredAccess = GENERIC_READ | GENERIC_WRITE ;
				dwShareMode = FILE_SHARE_READ | FILE_SHARE_WRITE ;
				dwCreationDistribution = OPEN_ALWAYS ;
				break ;

		default :
				return NULL ;
		} ;

	if (pfile->use_wchar)
		handle = CreateFileW (
					pfile->path.wc,				/* pointer to name of the file */
					dwDesiredAccess,			/* access (read-write) mode */
					dwShareMode,				/* share mode */
					0,							/* pointer to security attributes */
					dwCreationDistribution,		/* how to create */
					FILE_ATTRIBUTE_NORMAL,		/* file attributes (could use FILE_FLAG_SEQUENTIAL_SCAN) */
					NULL						/* handle to file with attributes to copy */
					) ;
	else
		handle = CreateFile (
					pfile->path.c,				/* pointer to name of the file */
					dwDesiredAccess,			/* access (read-write) mode */
					dwShareMode,				/* share mode */
					0,							/* pointer to security attributes */
					dwCreationDistribution,		/* how to create */
					FILE_ATTRIBUTE_NORMAL,		/* file attributes (could use FILE_FLAG_SEQUENTIAL_SCAN) */
					NULL						/* handle to file with attributes to copy */
					) ;

	if (handle == INVALID_HANDLE_VALUE)
		return NULL ;

	return handle ;
} /* psf_open_handle */

This weakness involves numeric computation errors, such as integer overflows, underflows, or precision losses, which can lead to miscalculations and exploitable behaviors in software.