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Smuggling data in pointers
While reading up on The ABA Problem I came across a fantastic hack. The ABA problem, in a nutshell, results from the inability to atomically access both a pointer and a "marked" bit at the same time (read the wikipedia page). One fun, but very hackish solution is to "smuggle" data in a pointer. Example:#include "stdio.h"void * smuggle(void * ptr, int value){ return (void *)( (long long)ptr | (value & 3) );}int recoverData(void * ptr){ return (long long)ptr & 3;}void * recoverPointer(void * ptr){ return (void *)( (long long)ptr & (~3) );}int main(...