The algorithm works, though it doesn't distinguish between the parent and child - the first process to call check_fork() after the fork will return false, and t

The algorithm works, though it doesn't distinguish between the parent and child - the first process to call check_fork() after the fork will return false, and the second process to call it will return true. (Note that upon returning true, it should remap and reset the state.) This is sufficient for the use case of reseeding a PRNG, though not for your signal handler/file descriptor use case. The problem with the algorithm (which I'm discussing on another subthread) is that the increment of the shared counter needs to be atomic, and the integers need to be 64 bits to avoid wraparound, and I'm not sure that all architectures support atomic 64 bit increments. Edit: I just realized that check_fork() would spuriously return true in the first process after the second process calls it, which isn't so nice. Maybe this can be prevented by comparing before you increment, but then I think there might be a race condition? It would be helpful if geocar could provide some pseudocode so we're not left guessing how the algorithm works.