Date: Fri, 16 May 2008 17:41:02 +0200 From: Jille Timmermans <jille@quis.cx> To: freebsd-hackers@freebsd.org Subject: Trying (not) to crash with libpthread (6.3-RELEASE) Message-ID: <482DAB0E.70600@quis.cx>
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Hello,
I'm trying to catch SIGSEGV, to be able to run 'unchecked' (possibly
crashing) code.
And not letting the entire program die, but just kill that thread.
So I wrote some testing code.
But, I ran into a problem; the signal-handler does not work when a
thread is created (or something like that).
The code below crashes on SIGSEGV, but should die in void sigcatcher(int);
If you uncomment the crashingthread(NULL); line, it will die in the
signal handler.
pthread_create seems to take over signal handling.
I quickly checked some pthread source, and it seems that it should call
my own handler.
(There might be an exception for some signals, but I didn't found that)
Can anyone explain me what is happening here ?
-- Jille
cc -lpthread below.c
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#include <signal.h>
#include <err.h>
int success=0;
void
sigcatcher(int sig) {
printf("[%p] signal %d\n", pthread_self(), sig);
printf("Test (probably) succeeded\n");
fflush(NULL);
success=1;
exit(0);
}
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();
}
int
main(int argc, char **argv) {
pthread_t thr;
if(signal(SIGSEGV, sigcatcher)==SIG_ERR)
err(1, "signal(SIGSEGV, catchz0r)");
//crashingthread(NULL);
pthread_create(&thr, NULL, crashingthread, NULL);
sleep(3);
return 0;
}
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