#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <semaphore.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <time.h>
#include <pthread.h>
#include <errno.h>


typedef struct Arguments {
    bool* flag;
    timespec* tm;
    sem_t* semForWrite;
    sem_t* semForRead;
    unsigned int* localVar;
} arguments;



void *thread(void *args){
    puts("read thread started");
    arguments *argument = (arguments*) args;
    (*(argument->tm)).tv_sec = 0;
    (*(argument->tm)).tv_nsec = 100000000;
    while (*(argument->flag)){
        while (sem_trywait(argument->semForWrite) != 0) {
            nanosleep(argument->tm, NULL);
            if (!*(argument->flag))
                return 0;
        }
        printf("Readed: %u\n", *(argument->localVar));
        sem_post(argument->semForRead);
        sleep(1);
    }
    pthread_exit(NULL);
}

int main(){
    arguments args;
    sem_t *semForWrite;
    sem_t *semForRead;
    unsigned int *localVar;
    char SemForReadName[] = "some_random_name_read_7";
    char SemForWriteName[] = "some_random_name_write_7";
    char SharedMemoryName[] = "some_random_mem_name_7";
    bool flag = true;
    pthread_t threadInit;
    timespec tm;

    int fd = shm_open(SharedMemoryName, O_CREAT | O_RDWR, 0777);
    ftruncate(fd, sizeof(unsigned int));
    localVar = (unsigned int*)mmap(0, sizeof(unsigned int), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);

    semForWrite = sem_open(SemForWriteName, O_CREAT, 0644, 0);
    semForRead = sem_open(SemForReadName, O_CREAT, 0644, 0);

    args.tm = &tm;
    args.flag = &flag;
    args.localVar = localVar;
    args.semForRead = semForRead;
    args.semForWrite = semForWrite;

    if(pthread_create(&threadInit, NULL, &thread, (void*)&args)){
        return EXIT_FAILURE;
    }

    getchar();

    flag = false;

    pthread_join(threadInit, NULL);

    sem_close(semForRead);
    sem_unlink(SemForReadName);
    sem_close(semForWrite);
    sem_unlink(SemForWriteName);

    munmap(&localVar, 4);
    close(fd);
    shm_unlink(SharedMemoryName);

    return EXIT_SUCCESS;
}