79 lines
1.2 KiB
C
79 lines
1.2 KiB
C
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <signal.h>
|
|
#include <sys/wait.h>
|
|
|
|
int p[2];
|
|
|
|
void sigcont() {
|
|
signal(SIGCONT,sigcont); /* reset signal */
|
|
printf("CHILD: Got SIGCONT\n");
|
|
exit(0);
|
|
}
|
|
|
|
void sigstop() {
|
|
signal(SIGSTOP,sigstop); /* reset signal */
|
|
printf("CHILD: Got SIGSTOP\n");
|
|
exit(1);
|
|
}
|
|
|
|
void childloop(void)
|
|
{
|
|
signal(SIGCONT,sigcont); /* set function calls */
|
|
signal(SIGSTOP,sigstop); /* set function calls */
|
|
printf("Child %d going to loop...\n", getpid());
|
|
write(p[1], "", 1);
|
|
close(p[1]);
|
|
close(p[0]);
|
|
for(;;){
|
|
/* loop for ever */
|
|
printf(".");
|
|
usleep(500);
|
|
}
|
|
exit(0);
|
|
}
|
|
|
|
int
|
|
main() {
|
|
int pid, child, cstatus;
|
|
char dummy[1];
|
|
|
|
/* get child process */
|
|
|
|
if(pipe(p)){
|
|
perror("pipe");
|
|
exit(1);
|
|
}
|
|
if ((pid = fork()) < 0) {
|
|
perror("fork");
|
|
exit(2);
|
|
}
|
|
|
|
if (pid == 0) {
|
|
childloop();
|
|
}
|
|
else /* parent */
|
|
{
|
|
read(p[0], &dummy, 1);
|
|
close(p[1]);
|
|
close(p[0]);
|
|
sleep(2);
|
|
printf("PARENT: sending SIGSTOP\n");
|
|
kill(pid,SIGSTOP);
|
|
sleep(4);
|
|
|
|
printf("PARENT: sending SIGCONT\n");
|
|
kill(pid,SIGCONT);
|
|
|
|
child = wait(&cstatus);
|
|
if(child == pid && cstatus == 0)
|
|
exit(0);
|
|
else
|
|
{
|
|
printf("PARENT: child exited with status %d\n", cstatus);
|
|
exit(1);
|
|
}
|
|
}
|
|
}
|