On Wed, Oct 16, 2013 at 5:15 PM, Friedrich Locke
<[email protected]>wrote:
> Hi folks,
>
> i am writing a program that:
>
> 0) manages to handle sigchld signals,
> 1) creates 100 process
> 2) put the childs to sleep 1 second
> 3) loops (the parent process) until 100 child process have been died.
>
> It is not working, why ?
>
> Thanks for you time and cooperation.
>
> Best regards,
> Fried.
>
>
> PS: the source code below:
>
> #include <sys/types.h>
> #include <sys/wait.h>
>
> #include <signal.h>
> #include <stdio.h>
> #include <unistd.h>
>
> unsigned long c;
>
> void
> hdlchld(const int s)
> {
> unsigned long p;
> int x;
>
> p = waitpid(-1, &x, WNOHANG | WCONTINUED | WUNTRACED);
> fprintf(stdout, "%lu\n", p);
> if (p + 1) {
> c++;
> fprintf(stdout, "pid: %lu\n died", p);
> }
> }
>
> int
> main(int argc, char **argv)
> {
> struct sigaction s;
> unsigned long i, p;
> int x;
>
> s.sa_handler = hdlchld;
> sigemptyset(&s.sa_mask);
> sigaddset(&s.sa_mask, SIGCHLD);
> s.sa_flags = 0;
>
> if (sigaction(SIGCHLD, &s, NULL) == -1) return 110;
>
> for (i = 0; i < 100; i++) {
> p = fork();
> if (p == -1ul) break;
> if (!p) break; /* child */
> }
> if (p == -1ul) return 1;
> if (p) while (c < i) sleep(1); /* parent */
> else sleep (1); /* child */
> return 0;
> }
>
>
- Declare p as pid_t in both functions.
- Check fork's return value against -1 (not -1ul)
- If you spawn n childs don't expect hdlchld to be called n times. I ran
your program under linux (here, in my work, I don't have OpenBSD) and it
run forever. Whth the following change the program works like, I suposse,
you expect:
void
hdlchld(const int s)
{
pid_t p;
int x;
while(1){
p = waitpid(-1, &x, WNOHANG | WCONTINUED | WUNTRACED);
fprintf(stdout, "%d\n", p);
if (p > 0) {
c++;
fprintf(stdout, "pid: %d died (%lu)\n", p, c);
}
else
break;
}
}
Regards
