SA_SIGINFO and si_pid

[Jonathan Steel]

Hi

In the SIGCHLD signal handler of parent process, I need to get the pid 
of the child when the child dies. To do this I'm using sigaction with 
the SA_SIGINFO flag. But the siginfo_t->si_pid member does not seem to 
be set.

I found the following post from Otto that seems to say that what I'm 
trying to do may not work on OpenBSD.

http://www.archivum.info/fa.openbsd.tech/2008-02/msg00124.html

Ive tried the following code on linux and everything works great, but on 
OpenBSD it doesn't work. I've tried it on 3.8 and 4.2, and I'm currently 
downloading 4.4 to see if it works on there.

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>


void signalChild(
   int signal, siginfo_t* info, void* notUsed
){
   printf("Entering signal handler!\n");
   if ( info == NULL )
   {
       printf("siginfo is NULL...aborting!\n");
       exit(1);
   }
   printf("Handling signal %d at %p\n", signal, info->si_addr);
   printf("PID: %d\t \n", info->si_pid);
   printf("Signal code: %d\n", info->si_code );
}


int main()
{
   struct sigaction child;
   sigemptyset ( &child.sa_mask );
   child.sa_sigaction = &signalChild;
   child.sa_flags = 0;
   child.sa_flags |= SA_SIGINFO;
   child.sa_flags &= ~SA_NOCLDSTOP;

   if ( sigaction( SIGCHLD, &child, NULL ) == -1 )
   {
       fprintf( stderr, "Error with signal setup.  Errno: %i\n", errno );
       exit( 1 );
   }

   int pid = fork();

   if ( pid == 0 )
   {
       fprintf( stderr, "PID: %i\n", getpid() );
       exit(0);
   }

   sleep( 1 );
   exit(0);
}


Does anybody know how I'm to accomplish this, or why it doesn't work?

Thank You

Jonathan Steel