Clueless or careless?
A customer program worked for many years till one of the transaction
messages had a few bytes added.
Looking into it I discovered that the program had only worked because
the receive buffer was followed by another buffer which was used in a
later sequence. Only when also that buffer overflowed some critical
integers got overwritten and used as index in tables that gave a lot
of fun.
Well, as all here know, C is fun :-)