SIGCONT signal generated automatically

[JoseLuis2]

Hi,

In this program, why is SIGCONT signal generated when only SIGUSR1 signal is sent to the process?

#include <stdio.h>
#include <signal.h>


int fib(int n)
{
  if (n == 0 || n == 1)
    return n;
  else
    return (fib(n-1) + fib(n-2));
}



void SignalHandler(int sig)
{

          printf("SIGNAL: %d\n", sig);
}


int main()
{
        int i;

        signal(SIGUSR1, SignalHandler);
        signal(SIGCONT, SignalHandler);
        signal(SIGTERM, SignalHandler);



        for(i=0; i< 100; ++i)
        {
                fib(35);
        }

}

------------------------------------------------
[fraapp31_cotafac]/tmp# a.out
SIGNAL: 26
SIGNAL: 16

[fraapp31_cotafac]/tmp# uname -a
HP-UX fraapp31 B.11.23 U ia64 1849578169 unlimited-user license

Thanks in advance.

Regards, Jose Luis.

[laurentmenase]

Hello Jose Luis,

1) printf() is not a async sinal safe function so must not be used in  a signal handler

2) with the following program you should see the signal for SIGCONT immediately

3) do you ^Z before sending a kill -USR1 to the process? ( I think I missed the initial question in my previous points), if yes, to restart a SIGCONT signal is received by the process, I don't reproduce, so how do you generate the signal

#include <stdio.h>
#include <signal.h>


int fib(int n)
{
  if (n == 0 || n == 1)
    return n;
  else
    return (fib(n-1) + fib(n-2));
}


void SignalHandlerCONT(int sig)
{

          write(1,"SIGNAL: CONT \n", strlen("SIGNAL: CONT \n"));
}
void SignalHandler(int sig)
{

          write(1,"SIGNAL: TERM \n", strlen("SIGNAL: CONT \n"));
}
void SignalHandlerUSR(int sig)
{
          write(1,"SIGNAL: USR1 \n", strlen("SIGNAL: CONT \n"));
}


int main()
{
        int i;
        signal(SIGUSR1, SignalHandlerUSR);
        signal(SIGCONT, SignalHandlerCONT);
        signal(SIGTERM, SignalHandler);

        for(i=0; i< 100; ++i)
        {
                fib(35);
        }

}

I am an HPE Employee (HPE Community)

[JoseLuis2]

Hi ,

First, the program is compiled and launched:

[fraapp31_cotafac]/tmp# cc -V
cc: HP aC++/ANSI C B3910B A.05.55 [Dec 04 2003]
[fraapp31_cotafac]/tmp# uname -a
HP-UX fraapp31 B.11.23 U ia64 1849578169 unlimited-user license
[fraapp31_cotafac]/tmp#
[fraapp31_cotafac]/tmp# cc laurentmenase_signal.c -o laurentmenase_signal
[fraapp31_cotafac]/tmp#
[fraapp31_cotafac]/tmp# laurentmenase_signal
SIGNAL: 26
SIGNAL: 16

In other terminal, SIGUSR1 signal is sent to the program:

[fraapp31_cotafac]/fac/desa/cotafac/madrid/trunk/fuentes/Procesos/src# ps -ef| grep  laurentmenase_signal
cotafac    688   482 96 20:40:10 pts/0       00:05 laurentmenase_signal
cotafac    691   563  0 20:40:15 pts/1       00:00 grep laurentmenase_signal
[fraapp31_cotafac]/fac/desa/cotafac/madrid/trunk/fuentes/Procesos/src# kill -SIGUSR1 688
[fraapp31_cotafac]/fac/desa/cotafac/madrid/trunk/fuentes/Procesos/src#

Thanks for your help!!

Regards, Jose Luis

[laurentmenase]

Hello Jose Luis

Even on 11.23 I do not reproduce and get only SIGUSR1.  you may try to tusc the kill and the a.out  ( tusc -f -o /var/tmp/xy.t ./xy
and
tusc -f -o /var/tmp/kill.t kill  -USR1 <pid>

Best regards,

Laurent 

[JoseLuis2 · Accepted solution]

Hi,

The problem was that I was using ksh built in kill instead of kill command (/usr/bin/ksh). This text is an extract for "man ksh":

"Signals are given either by number or name (as given in signal(5), stripped of the prefix SIG). The signal names are listed by kill -l. No default exists; merely typing kill does not affect the current job. If the signal being sent is TERM (terminate) or HUP (hangup), the job or process is sent a CONT (continue) signal when stopped. The process argument can be either a process ID or job. If the first argument to kill is a negative integer, it is interpreted as a sig argument and not as a process group. See also kill(1)."

Thanks for your help!

Regards, Jose Luis.

[Sunitha_Mod]

Hello Jose Luis,

That's excellent!

We are extremely glad to know you were able to find the solution, and we appreciate you for keeping us posted.