> signal (SIGCHLD, child_signal_handler);

Make sure you check that this works more than once... signal() is
a deprecated interface function, and some implementations required
you to re-specify the handler every time the signal was delivered,
at least for certain signals.

The truth is that for your purposes you could get by without doing
the SIGCHLD thing at all--running the waitpid() loop before each
fork() would enforce a small bound on the number of zombies.

Dave Eckhardt