Date: Fri, 16 May 2008 12:55:58 -0400 From: Mike <deathjestr@gmail.com> To: "Jille Timmermans" <jille@quis.cx> Cc: freebsd-hackers@freebsd.org Subject: Re: Trying (not) to crash with libpthread (6.3-RELEASE) Message-ID: <44b564930805160955r76d6861fo1949c7f4d5b71ca5@mail.gmail.com> In-Reply-To: <482DAB0E.70600@quis.cx> References: <482DAB0E.70600@quis.cx>
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> void
> sigcatcher(int sig) {
> printf("[%p] signal %d\n", pthread_self(), sig);
> printf("Test (probably) succeeded\n");
> fflush(NULL);
> success=1;
> exit(0);
> }
Take a look at the man page for sigaction(2). Here's an excerpt:
"All functions not in the above lists are considered to be unsafe with
respect to signals. That is to say, the behaviour of such functions when
called from a signal handler is undefined. In general though, signal
handlers should do little more than set a flag; most other actions are
not safe."
> void *
> crashingthread(void *nada) {
> /* This will likely crash */
> char *x=malloc(1);
>
> if(signal(SIGSEGV, sigcatcher)==SIG_ERR)
> err(1, "signal(SIGSEGV, catchz0r)");
>
> x[666]=0;
>
> /* HOPEFULLY NOT REACHED (aargh! die harder!) */
>
> int i;
> for(i=1; 999999>i; i++)
> x[i]=0;
>
> /* NOT REACHED (either killed, or exit()'ed in sigcatcher) */
> abort();
> }
Something like *(int*)0 = 0 is probably an easier, more reliable way to
crash your program. Maybe not quite as much fun though. ;-)
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