C signaling demo

#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>

void parent_work(int signo);
void child_work(int signo);

void syserr_quit(char *msg);

pid_t parent_pid;
pid_t child_pid;

int main () {
    parent_pid = getpid();
    printf("parent pid: %d\n", parent_pid);

    pid_t pid = fork();
    if (pid < 0) {
        syserr_quit("fork error");
    } else if (pid == 0) {
        signal(SIGUSR2, child_work);
        while (1) {}
    } else {
        child_pid = pid;
        printf("child pid: %d\n", pid);
        signal(SIGUSR1, parent_work);
        while (1) {}
    }
}

void child_work (int signo) {
    sleep(1); // fake child work

    // signal parent that a write is now possible
    printf("send signal to %d\n", parent_pid); fflush(stdout);
    if (kill(parent_pid, SIGUSR1) < 0) syserr_quit("kill error");
    printf("signal sent\n"); fflush(stdout);

    // wait for parent signal
    pause();
}

void parent_work (int signo) {
    sleep(1); // fake parent work

    // signal child that a read is possible
    printf("send signal to %d\n", child_pid); fflush(stdout);
    if (kill(child_pid, SIGUSR2) < 0) syserr_quit("kill error");
    printf("signal sent\n"); fflush(stdout);

    // wait for child signal
    pause();
}

void syserr_quit(char *msg) {
    perror(msg);
    exit(EXIT_FAILURE);
}