consumer.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#include <semaphore.h>
#include <signal.h>

typedef struct
{
    int number;
    char data[256];
} Frame;

void sig_handler()
{
    shm_unlink("/shm_buffer");
    sem_unlink("/shm_empty");
    sem_unlink("/shm_data");
}

int main(void)
{

    int fd = shm_open("/shm_buffer", O_RDONLY, 0666);
    if (fd == -1)
    {
        printf("error: cant open the shm buffer");
    }
    sem_t *empty_sem = sem_open("/shm_empty", 0);
    sem_t *sem = sem_open("/shm_data", 0);

    Frame *frame = mmap(NULL, sizeof(Frame), PROT_READ, MAP_SHARED, fd, 0);
    close(fd);
    signal(SIGINT, sig_handler);

    int frame_num = 0;
    sem_post(empty_sem);
    while (frame_num < 100)
    {
        sem_wait(sem); // blocks until the producer signals
        printf("Consumer read frame %d: %s\n", frame->number, frame->data);
        frame_num = frame->number;

        sem_post(empty_sem);
    }
    munmap(frame, sizeof(Frame));
    shm_unlink("/shm_buffer");
    sem_unlink("/shm_empty");
    sem_unlink("/shm_data");
    return 0;
}