//---------------------------------------------------------
// com_shm.cc
//---------------------------------------------------------

#include "check.h"    // check

#include <cstring>    // strlen
#include <iostream>   // cout
#include <sys/shm.h>  // ftok, shmget, shmat
#include <sys/wait.h> // wait
#include <unistd.h>   // fork

//---------------------------------------------------------

int main()
{
    int key = check(ftok("/tmp", 3));
    int shmid = check(shmget(key, 100, IPC_CREAT | 0600));
    char *s = nullptr;

    if (check(fork())) // parent/reader
    {
        wait(nullptr); // wait for child
        s = static_cast<char *>(check(shmat(shmid, nullptr, 0)));
        std::cout << "parent/reader: " << s << std::endl;
    }
    else // child/writer
    {
        s = static_cast<char *>(check(shmat(shmid, nullptr, 0)));
        std::cout << " child/writer: ";
        for (char c = 'a'; c <= 'z'; ++c)
            std::cout << (*s++ = c);
        *s = 0; // string ending '\0'
        std::cout << std::endl;
    }
}

//---------------------------------------------------------