A reentrant function is one that can be reentered while an ongoing invocation is still running. It's simpler than it sounds; check out this pseudo-code snippet:
signal_handler(sig) { my_foo(); < ... > }my_foo(){ char mybuf[MAX]; <...>}do_the_work_mate(){ my_foo(); <...>}
Now imagine this sequence of activity:
-
The function my_foo() is invoked by the business logic function do_the_work_mate(); it operates on the local buffer mybuf
-
While this is still running, a signal is dispatched to this process
-
The signal handler code preempts whatever was executing at the moment it occurred and runs
-
It reinvokes the function my_foo()
-
So, there we see it: the function my_foo() is reentered. By itself, that's OK; the important ...
