Honestly kind of irrelevant

Posted Oct 31, 2024 18:10 UTC (Thu) by NYKevin (subscriber, #129325)
In reply to: Honestly kind of irrelevant by Wol
Parent article: realloc() and the oversize importance of zero-size objects

Because you don't need to. The developer can just do this:

#define malloc_s(size) (size == 0? (void*)NULL : malloc(size))
#define realloc_s(ptr, size) (size == 0 ? free(ptr), (void*)NULL : realloc(ptr, size))

And then the compiler can optimize that back into a malloc/realloc call easily enough, if it knows that malloc/realloc have the appropriate semantics on a given platform.

Getting unique non-dereferencable pointers is harder, and IMHO should not be done, because (as I've explained elsewhere in the thread) it is cheaper to have a global u64 and atomically increment it (malloc takes a lock in almost any sensible implementation). If you somehow manage to allocate over 16 quintillion numbers in this fashion (so that it wraps), then you probably should be using UUIDs instead of 64-bit integers in the first place.