int BUF_MEM_grow(BUF_MEM *str, size_t len)
	{
	char *ret;
	size_t n;

	if (str->length >= len)
		{
		str->length=len;
		return(len);
		}
	if (str->max >= len)
		{
		memset(&str->data[str->length],0,len-str->length);
		str->length=len;
		return(len);
		}
	/* This limit is sufficient to ensure (len+3)/3*4 < 2**31 */
	if (len > LIMIT_BEFORE_EXPANSION)
		{
		BUFerr(BUF_F_BUF_MEM_GROW,ERR_R_MALLOC_FAILURE);
		return 0;
		}
	n=(len+3)/3*4;
	if (str->data == NULL)
		ret=OPENSSL_malloc(n);
	else
		ret=OPENSSL_realloc(str->data,n);
	if (ret == NULL)
		{
		BUFerr(BUF_F_BUF_MEM_GROW,ERR_R_MALLOC_FAILURE);
		len=0;
		}
	else
		{
		str->data=ret;
		str->max=n;
		memset(&str->data[str->length],0,len-str->length);
		str->length=len;
		}
	return(len);
	}