*This condition will probably never be met, but it is theoretically
possible that the code could still fail at this point. Catch all errors,
and exit, ruthlessly.
The code was only checking whether all of the bytes were read,
but there are other errors that can be caught via errno.
Enforce strict errno handling, when generating random
numbers for command `setmac`.
previously, it was always initialised, but now it's only
initialised if '?' is used on a mac address character in
command `setmac`
this is done by simply moving mac address character
randomisation to a separate function
If one of the checksums was valid, but the other was not,
errno would be set to E_CANCELED, but then the buffer would
be modified anyway; this is acceptable behaviour, and errno
would later be reset writing the GBE file, which is done
only on the condition that the buffer was modified, but
it's also a good idea to reset it here just in case.
This is not a bugfix, and no behavioural changes will be
observed by the user, but this may *prevent* a bug in the
future, so let's pre-fix that bug now.
in any C program, main() should not contain detailed logic.
ideally, the main() function should only be a skeleton, showing
the overall logic flow of the program. split writing gbe files
into a separate function, to satisfy this criteria.
Leah Rowe