I agree with that statement, but it has nothing to do with snprintf() versus e.g. strcpy_s(), where you have exactly the same requirement to pass the right size

I agree with that statement, but it has nothing to do with snprintf() versus e.g. strcpy_s(), where you have exactly the same requirement to pass the right size. (Separately, there's a discussion about how many bytes you are allowed to read from the _source_, but to fix that, you need something like the Linux kernel's strscpy(), which isn't really widely supported in userspace.)