% python qcowtest.py < my-seed.iso
Source was raw file, size 374784
% stat -c '%s' my-seed.iso
374784

% python qcowtest.py < rhel-guest-image-7.4-87.x86_64.qcow2
Source was qcow file, virtual size 10737418240
% qemu-img info rhel-guest-image-7.4-87.x86_64.qcow2  | grep virtu
virtual size: 10G (10737418240 bytes)
% stat -c '%s' rhel-guest-image-7.4-87.x86_64.qcow2
505576448