As I understand that doesn't imply that it's not undefined to pass NULL pointers. While not what most users expect/want it's possible to this is just a wrapper

As I understand that doesn't imply that it's not undefined to pass NULL pointers. While not what most users expect/want it's possible to this is just a wrapper around an memcpy() which will only be correct to call with valid destination and source pointers even if the length is zero.