Ignoring the multiplication issue, I think once again it all comes down to communicating intent. If you want to allocate zeroed memory, use calloc. If you don't

Ignoring the multiplication issue, I think once again it all comes down to communicating intent. If you want to allocate zeroed memory, use calloc. If you don't need your memory to necessarily be zeroed, use malloc. I'm agreeing with you here - if your intent is to have copy-on-write functionality, that's not what you're communicating when you use calloc. It's okay for an implementation to try to optimize given the constraints of intent, but I agree that if an implementation is doing something non-straightforward (copy-on-write in this case), that is a smell that perhaps the API needs to expose an additional layer.