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Re: GDB is not trapping SIGINT


Daniel Jacobowitz wrote:
On Sun, Apr 02, 2006 at 11:58:59PM -0500, Andy Howell wrote:
Hello,

I'm having problems getting GDB to not pass SIGINT to my program. In my main thread I do a sigwait for SIGINT. When I'm debugging, I don't want this called. "info handle" shows that SIGINT should not be being passed to my app.

I using GDB 6.3 on RH Linux.

But how are you using it? :-) An example, please.

> You also did not mention what kernel version you are using; at least > one sigwait-related kernel bug has been reported. And it looks like > it is still present in current 2.6 kernels, so you may want to report > this to the kernel developers. sys_rt_sigtimedwait calls > dequeue_signal, but never lets ptrace see it. Maybe the bits from > get_signal_to_deliver can be moved into dequeue_signal now. >

Daniel,

Sorry for previous lack of details. It does seem to be Linux specific. I see the same behavior in Redhat Linux 2.4.21-4.EL and 2.6.9-22.0.2.EL, as well as Fedora 3 2.6.12. On solaris 2.8 it works fine.

It sounds like without a kernel patch, I'm out of luck. Thanks for your help.

For what its worth, my program first creates a signal set, block new threads from seeing them, and then the main thread waits for a signal:

	::sigemptyset( &set );
	::sigaddset( &set, SIGINT );
	::sigaddset( &set, SIGQUIT );
	::sigaddset( &set, SIGUSR2 );
	.... more signals

	// Block new threads from getting signals
	pthread_sigmask( SIG_BLOCK &set, NULL );

	// Create a bunch of threads
	.....

	// wait for signal
	
	do {
	  sigErr = sigwait( &set, &sig );
 	  if( sig == SIGUSR2 ) {
	    doSomething(...)
	  }
        while( sig = SIGUSR2 )

// Do cleanup and exit

Thanks,

Andy


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