Just hit this when trying to adjust some gpt-in-ccd settings
Also - easy case to reproduce (without the 'gpt add' step it does not trigger)
dd if=/dev/zero bs=1m count=10 > test.img
gpt create test.img
gpt add -t ffs test.img
dd if=test.img of=smaller.img bs=1m count=9
gpt destroy smaller.img
One thought, there could be some kind of force option to bypass the size check - possibly by truncating or ignoring oversized entries, which could be useful for recovering damaged disk images
Thanks
David