#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h> /* Definition of AT_* constants */
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <signal.h>

static const char *kat = "/tmp/FIFO-TMP-SERWER";
static const char *kat_1 = "/tmp/FIFO-TMP-1-";
static const char *kat_2 = "/tmp/FIFO-TMP-2-";

int f, f1, f2;
void end()
{
    close(f);
    close(f1);
    close(f2);
    unlink(kat);
    exit(0);
}

int main()
{
    pid_t pid;
    char kat_1_pid[100];
    char kat_2_pid[100];
    signal(SIGTERM, end);
    signal(SIGINT, end);
    if (mkfifo(kat, 0600) == -1)
    {
        printf("mkfifo open error\n");
        return;
    }
    if ((f = open(kat, O_RDONLY)) == -1)
    {
        unlink(kat);
        printf("kat open error\n");
        return;
    }
    for (;;)
    {
        read(f, &pid, sizeof(pid_t));
        printf("pid: %d\n", pid);
        strcpy(kat_1_pid, kat_1);
        strcpy(kat_2_pid, kat_2);
        sprintf(kat_1_pid + strlen(kat_1), "%d", pid);
        sprintf(kat_2_pid + strlen(kat_2), "%d", pid);
        // printf(kat_1_pid);
        // printf(kat_2_pid);
        if ((f2 = open(kat_2_pid, O_RDONLY)) == -1)
        {
            unlink(kat);
            close(f);
            printf("kat2 open error\n");
            return;
        }
        printf("f2 open\n");
        if ((f1 = open(kat_1_pid, O_WRONLY)) == -1)
        {
            unlink(kat);
            close(f2);
            close(f);
            printf("kat1 open error\n");
            return;
        }
        printf("f1 open\n");
        double d2, d;
        read(f2, &d, sizeof(double));
        d2 = d * d;
        write(f1, &d2, sizeof(double));
        close(f1);
        close(f2);
    }
}