There's no use assigning the output of strtoul() to a 32-bit variable
then checking that against ULONG_MAX. Instead use a "unsigned long"
as the temporary variable. Also, only check against UID_MAX/GID_MAX;
these are both going to be smaller than ULONG_MAX on both 32- and 64-bit
platforms.
If the user deletes a field while editing (as an easy way of making
that field empty) then "save" for that field will not get initialized
before referencing it when constructing the new GECOS field.
xtraeme