Ignore the prefix and always treat strncpy() as a special binary data operation for an era where shaving bytes on storage was important. It's for copying into a struct with array fields or direct to an encoded block of memory. In that context you will never be dependent on the presence of NUL. The only safe usage with strings is to check for NUL on every use or wrap it. At that point you may as well switch to a new function with better semantics.

> an era where shaving bytes on storage was important

Fixed size strings don’t save bytes on storage tho, when the bank reserves 20 bytes for first name and you’re called Jon that’s 17 bytes doing fuckall.

What they do is make the entire record fixed size and give every field a fixed relative position so it’s very easy to access items, move record around, reuse allocations (or use static allocation), … cycles is what they save.