So if I got it right, you're using fork(2) as a glorified shared memory interface. If my memory is (also) right, you can allocate shared read-only mapping with

So if I got it right, you're using fork(2) as a glorified shared memory interface. If my memory is (also) right, you can allocate shared read-only mapping with shm_open(3) + mmap(2) in parent process, and open it as a private copy-on-write mapping in child processes.