We deliberately allocate a very small amount of space for the alternate signal stack—just 100 kilobytes. Needless to say, it overflows quickly and segfaults; our handler for SIGSEGV runs, printing out some stats:
$ ./altstack 100Alt signal stack size = 102400Running: signal SIGUSR1 flags: SA_NODEFER | SA_ONSTACK | SA_RESTARTProcess awaiting signals ...
In another Terminal window, run the shell script:
$ ./bombard_sig.sh $(pgrep altstack) 120Sending 120 instances of signal SIGUSR1 to process 12811 ...
Now, the output in the original window:
<...> s=1 ; total=1; stack 0xa20ff0 s=2 ; total=2; stack 0xa208f0 s=3 ; total=3; stack 0xa201f0--snip-- s=1 ; total=49; stack 0xa0bff0 s=2 ; total=50; ...
