processes.c

#include <stdio.h>
#include <unistd.h>
#include <math.h>
#include <sys/time.h>
#include <time.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#define CHILDREN_COUNT 2

int childs[CHILDREN_COUNT];
char *getCurrentTime();
void childHandler(int sig);
void parentHandler(int sig, siginfo_t *info, void *context);

int main()
{
    struct sigaction sa;
    sa.sa_flags = SA_SIGINFO;
    sa.sa_sigaction = parentHandler;
    sigaction(SIGUSR2, &sa, NULL);
    for (int i = 0; i < CHILDREN_COUNT; i++)
    {
        int pid = fork();
        childs[i] = pid;
        if (pid == 0)
        {
            signal(SIGUSR1, childHandler);
            for(int j = 0; j < 10; j++){
                printf("Child %d paused...\n", getpid());
                pause();
            }

            exit(0);
        }
        else if (pid > 0)
        {
        }
        else
        {
            printf("error");
            return -1;
        }
    }
    usleep(100);
    kill(childs[0], SIGUSR1);
    kill(childs[1], SIGUSR1);
    for(int j = 0; j < 10; j++){
        printf("Parent %d paused...\n", getpid());
        pause();
    }
    return 0;
}

void childHandler(int sig)
{
    printf("Signal %d\n", sig);
    if (sig == SIGUSR1)
    {
        static int n = 1;
        printf("CHILD GET %d %d %d %s\n", n, getpid(), getppid(), getCurrentTime());
        usleep(100);
        printf("CHILD SEND %d %d %d %s\n", n, getpid(), getppid(), getCurrentTime());
        kill(getppid(), SIGUSR2);
        n++;
    }
}

void parentHandler(int sig, siginfo_t *info, void *context)
{
    printf("Signal %d\n", sig);
    if (sig == SIGUSR2)
    {
        static int n = 1;
        printf("PARENT GET %d %d %d %s\n", n, getpid(), info->si_pid, getCurrentTime());
        usleep(100);
        printf("PARENT SEND %d %d %d %s\n", n, getpid(), info->si_pid, getCurrentTime());
        kill(info->si_pid, SIGUSR1);
        n++;
    }
}

char *getCurrentTime()
{
    char buffer[15];
    char *current_time;
    int millisec;
    struct tm *tm_info;
    struct timeval tv;

    gettimeofday(&tv, NULL);

    millisec = lrint(tv.tv_usec / 1000.0); // Round to nearest millisec
    if (millisec >= 1000)
    { // Allow for rounding up to nearest second
        millisec -= 1000;
        tv.tv_sec++;
    }

    tm_info = localtime(&tv.tv_sec);

    strftime(buffer, 15, "%H:%M:%S", tm_info);
    current_time = (char *)malloc(20 * sizeof(char));
    sprintf(current_time, "%s:%03d\n", buffer, millisec);
    return current_time;
}