[vdr] Re: caught signal 2

[hm@seneca.muc.de]

Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de> wrote:
> >>   dsyslog("PID = %d", getpid());
> >>
> >>to the SignalHandler() function in VDR/vdr.c. Maybe it gives you
> >>the process id of the process sending the signal - which might shed
> >>some more light on this.
> > 
> > Ehh.... getpid will print the PID of VDR (in his example 2659), not?

> I'm not sure about that - maybe it prints the pid of the interrupting
> process.

Unfortunately not with signal() but it is possible with sigaction(). 

A test program may look as follows: 

#include <stdio.h>
#include <signal.h>
#include <ucontext.h>
void my_signal_handler(int sig, siginfo_t *sigInfo, struct ucontext *scp) {
  printf("siginfo->si_code = %d\n", sigInfo->si_code);
  printf("siginfo->si_pid = %d\n",  sigInfo->si_pid);
  printf("siginfo->si_addr = %d\n", sigInfo->si_addr);
  exit(0);
}
int main (int argc, char **argv) {
  struct sigaction sa;
  int i, j;
  /* not this one! 
  sa.sa_handler = (void *)my_signal_handler;
  */
  /* but these two */
  sa.sa_sigaction = (void *)my_signal_handler;
  sa.sa_flags = SA_SIGINFO;
  sigaction (SIGINT, &sa, NULL);
  /* endless loop */
  while (1) {
    sleep (60);
  }
  exit (0); /* to keep gcc happy */
}

The we run this program from a shell and press Ctrl-C:

hm@nathan:~/tmp> ./sighnd
siginfo->si_code = 128
siginfo->si_pid = 0
siginfo->si_addr = 0

Hmmm - not very useful. BUT - if we send the signal from a remote process
instead of the parent shell: 

# echo $$
5881
# kill -INT 8743 (with 8743 being sighnd's PID)

and our program says

hm@nathan:~/tmp> ./sighnd
siginfo->si_code = 0
siginfo->si_pid = 5881
siginfo->si_addr = 5881
 
WOW!

So I'd suggest to replace the signal() calls in vdr.c by sigaction() and
dsyslog() the calling process's PID for debugging purposes :-)) 


I am still not sure about what happens on my box. It runs now 1.3.15 with
Werner's rc5 AC3 patches only. Plugins: remote, mp3, lcdproc. Seems to be
stable for now. But who knows. 

-- 
All progress is based upon a universal innate desire on the part of
every organism to live beyond its income.
		-- Samuel Butler