Subject: Re: [linux-audio-dev] pthreads and signals
From: David Olofson (david_AT_olofson.net)
Date: Wed May 14 2003 - 17:57:36 EEST
On Wednesday 14 May 2003 16.12, David Olofson wrote:
> [...]
> I believe the SDL parachute traps segfaults as well, BTW. I'll have
> a look...
It does indeed, but I can't find any special treatment. Looks like
just another signal.
However, according to 'man signal', it seems to me that SIGSEGV (and
some others) *are* a bit special. I concluded that you have to make
sure the thread that causes the segfault must be killed by the signal
handler, or weird things will happen. (Zombie, endless loop calling
the signal handler or something. My system seems to do the latter.)
This code Works Here(TM), or at least does what I think it should:
---8<------------------------------------------------------
#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
void handler(int sig)
{
signal(sig, SIG_DFL);
switch (sig)
{
case SIGSEGV:
puts("We got a segfault!");
pthread_exit(NULL);
break;
default:
puts("Unknown");
break;
}
}
void *crasher(void *arg)
{
long i = 42, *j = NULL;
signal(SIGSEGV, handler);
puts("crasher() started.");
sleep(3);
puts("crasher(): Let's crash!");
*j = i;
puts("crasher() ended. (How the f...!?)");
}
int main(int argc, char *argv[])
{
pthread_t thread;
puts("main() started.");
pthread_create(&thread, NULL, crasher, NULL);
while(1)
{
puts("main() is alive.");
sleep(1);
}
return 0;
}
------------------------------------------------------>8---
//David Olofson - Programmer, Composer, Open Source Advocate
.- The Return of Audiality! --------------------------------.
| Free/Open Source Audio Engine for use in Games or Studio. |
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`-----------------------------------> http://audiality.org -'
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