psf_fwrite (const void *ptr, sf_count_t bytes, sf_count_t items, SF_PRIVATE *psf)
{	sf_count_t total = 0 ;
	ssize_t	count ;

	if (bytes == 0 || items == 0)
		return 0 ;

	if (psf->virtual_io)
		return psf->vio.write (ptr, bytes*items, psf->vio_user_data) / bytes ;

	items *= bytes ;

	/* Do this check after the multiplication above. */
	if (items <= 0)
		return 0 ;

	while (items > 0)
	{	/* Break the writes down to a sensible size. */
		count = (items > SENSIBLE_SIZE) ? SENSIBLE_SIZE : items ;

		count = write (psf->file.filedes, ((const char*) ptr) + total, count) ;

		if (count == -1)
		{	if (errno == EINTR)
				continue ;

			psf_log_syserr (psf, errno) ;
			break ;
			} ;

		if (count == 0)
			break ;

		total += count ;
		items -= count ;
		} ;

	if (psf->is_pipe)
		psf->pipeoffset += total ;

	return total / bytes ;
} /* psf_fwrite */
The product divides a value by zero.