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

#include "svshm_string.h"

int main(void)
{
    int semid, shmid;
    char *addr;
    union semun arg, dummy;
    struct sembuf sop;

    /* Create shared memory and semaphore set containing one
       semaphore. */

    shmid = shmget(IPC_PRIVATE, MEM_SIZE, IPC_CREAT | 0600);
    if (shmid == -1)
        errExit("shmget");

    semid = semget(IPC_PRIVATE, 1, IPC_CREAT | 0600);
    if (semid == -1)
        errExit("semget");

    /* Attach shared memory into our address space. */

    addr = shmat(shmid, NULL, SHM_RDONLY);
    if (addr == (void *)-1)
        errExit("shmat");

    /* Initialize semaphore 0 in set with value 1. */

    arg.val = 1;
    if (semctl(semid, 0, SETVAL, arg) == -1)
        errExit("semctl");

    printf("shmid = %d; semid = %d\n", shmid, semid);

    /* Wait for semaphore value to become 0. */

    sop.sem_num = 0;
    sop.sem_op = 0;
    sop.sem_flg = 0;

    if (semop(semid, &sop, 1) == -1)
        errExit("semop");

    /* Print the string from shared memory. */

    printf("%s\n", addr);

    /* Remove shared memory and semaphore set. */

    if (shmctl(shmid, IPC_RMID, NULL) == -1)
        errExit("shmctl");
    if (semctl(semid, 0, IPC_RMID, dummy) == -1)
        errExit("semctl");

    exit(EXIT_SUCCESS);
}