[LCP]SIGFPE

[Jack Lloyd]

Well, it actually only says that ignoring this signal can result in an
infinte loop. I would presume this means using SIG_IGN, rather than
requiring that the signal handler must abort.

There is a workaround to this. Basically, use setjmp and longjmp. Do a
setjmp right before you do the potentially bad instruction, and do a
longjmp out of the signal handler.

I'm not totally sure that you're allowed to do longjmp inside a signal
handler (actually, I'm pretty sure it's undefined by POSIX). But I've seen
it done in several pieces of reasonable portable pieces of software. I've
never done this for SIGFPE but I've seen it for SIGILL and done it myself
for SIGPIPE.

-Jack

On 11 Jul 2002, devraj  sanyal wrote:

> This is the default behaviour of the kernel.
> on sigfpe the kernel loops on the signal
> again and again. check out the man page
> for signal.
>
>
>
>
> On Thu, 11 Jul 2002 madhav morje wrote :
> >Hello,
> >
> >I'm a novice in signal field. I was trying to out a simple
> >program (which I've pasted below). When the binary was executed,
> >signal handler for SIGFPE was executed continuously even though
> >I've written a signal handler for it.
> >
> >My query is, why kernel continuously gives this signal to my
> >program Or Am I missing something in my code??
> >
> >If I reset signal handler for SIGFPE to defualt one in the signal
> >handler function, then my program gets terminated.
> >
> >Regards,
> >Madhav.
> >
> >======================================================
> >#include <signal.h>
> >#include <stdio.h>
> >#include <unistd.h>
> >
> >void sighand(int sig)
> >{
> >  printf("\nSig Recd %d", sig);
> >  /*
> >  ** Should signal handler be reset here for SIGFPE to default
> >here ????
> >  */
> >}
> >
> >int main()
> >{
> >
> >struct sigaction act;
> >int j=10,k;
> >
> >act.sa_handler = sighand;
> >sigemptyset(&act.sa_mask);
> >act.sa_flags = 0;
> >
> >sigaddset(&act.sa_mask, SIGFPE);
> >
> >(void) sigaction(SIGFPE, &act, 0);
> >
> >k=j/0;
> >
> >printf("\ndone!!\n");
> >
> >return 0;
> >
> >}
> >======================================================
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> >
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