3

/* В родителе D(1), далее в цикле write() текст в pipe, A(2), Zero - блок семафора, read();
В ребенке в цикле D(2) - запуск родителя, read(), write(). A(1) */

#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>


int main() {
    int fd[2], result, N;

    size_t size;
    char resstring[14];
    char path[] = "task03.c";

    key_t key;
    struct sembuf mybuf;
    int semid;

    printf("Введите N: ");
    scanf("%d", &N);

    if (pipe(fd) < 0) {
        printf("Can\'t open pipe\n");
        exit(-1);
    }

    if ((key = ftok(path, 0)) < 0) {
        printf("Can\'t generate key");
        exit(-1);
    }

    if ((semid = semget(key, 1, 0666 | IPC_CREAT)) < 0) {
        printf("Can\'t create semaphore set\n");
        exit(-1);
    }

    //Add_1
    mybuf.sem_num = 0;
    mybuf.sem_op = 1;
    mybuf.sem_flg = 0;

    if (semop(semid, &mybuf, 1) < 0) {
        printf("Can\'t set value in semaphore\n");
        exit(-1);
    }

    result = fork();

    if (result < 0) {
        printf("Can\'t fork child\n");
        exit(-1);
    } else if (result > 0) {

        /* Parent process */

        //Decrease_1
        mybuf.sem_num = 0;
        mybuf.sem_op = -1;
        mybuf.sem_flg = 0;

        if (semop(semid, &mybuf, 1) < 0) {
            printf("Can\'t set value in semaphore\n");
            exit(-1);
        }

        for (int i = 0; i < N; ++i) {

            size = write(fd[1], "Hello, world!", 14);

            if (size != 14) {
                printf("Can\'t write all string to pipe\n");
                exit(-1);
            }

            //Add_2
            mybuf.sem_num = 0;
            mybuf.sem_op = 2;
            mybuf.sem_flg = 0;

            if (semop(semid, &mybuf, 1) < 0) {
                printf("Can\'t set value in semaphore\n");
                exit(-1);
            }
            //Zero
            mybuf.sem_num = 0;
            mybuf.sem_op = 0;
            mybuf.sem_flg = 0;

            if (semop(semid, &mybuf, 1) < 0) {
                printf("Can\'t set value in semaphore\n");
                exit(-1);
            }

            //Decrease_1
            mybuf.sem_num = 0;
            mybuf.sem_op = -1;
            mybuf.sem_flg = 0;

            if (semop(semid, &mybuf, 1) < 0) {
                printf("Can\'t set value in semaphore\n");
                exit(-1);
            }

            size = read(fd[0], resstring, 14);

            if (size < 0) {
                printf("Can\'t read all string to pipe\n");
                exit(-1);
            }
            printf("Parent read from the pipe: %s\n", resstring);
        }

        printf("Parent exit\n");
    } else {

        /* Child process */

        for (int i = 0; i < N; ++i) {
            //Decrease_2
            mybuf.sem_num = 0;
            mybuf.sem_op = -2;
            mybuf.sem_flg = 0;

            if (semop(semid, &mybuf, 1) < 0) {
                printf("Can\'t set value in semaphore\n");
                exit(-1);
            }

            size = read(fd[0], resstring, 14);

            if (size < 0) {
                printf("Can\'t read string from pipe\n");
                exit(-1);
            }
            printf("Child read from the pipe: %s\n", resstring);


            size = write(fd[1], "Hello, world!", 14);

            if (size != 14) {
                printf("Can\'t write all string to pipe\n");
                exit(-1);
            }

            //Add_1
            mybuf.sem_num = 0;
            mybuf.sem_op = 1;
            mybuf.sem_flg = 0;

            if (semop(semid, &mybuf, 1) < 0) {
                printf("Can\'t set value in semaphore\n");
                exit(-1);
            }
        }

        if (close(fd[0]) < 0) {
            printf("child: Can\'t close reading side of pipe\n");
            exit(-1);
        }

        if (close(fd[1]) < 0) {
            printf("child: Can\'t close writing side of pipe\n");
            exit(-1);
        }
    }

    return 0;
}