SPO-3-NIX RC3

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

#define SHMSZ 10

#define SHMGET_ERROR 10
#define SHMAT_ERROR 11
#define SHMDT_ERROR 12
#define SEMOP_ERROR 20
#define SEMGET_ERROR 21
#define SEMCTL_ERROR 22
#define READ_ERROR 30
#define WRITE_ERROR 31


int allocateMemory( char** shm )
{
    int shmid;          // shared memory segment ID
    key_t key = 5512;   // key for shared memory
    if ((shmid = shmget(key, SHMSZ, 0666)) < 0)
    {
        printf("shmid failed with error %s\n", strerror(errno));
        return(SHMGET_ERROR);
    }
    *shm = (char*)shmat(shmid, NULL, 0);
    if ( (int)(**shm) ==  -1)
    {
        printf("shmat failed with error %s\n", strerror(errno));
        return(SHMAT_ERROR);
    }
    return 0;
}


int main(int argc,char *argv[])
{

    key_t key1 = 12345;
    int semid;
    unsigned short semval;
    int cnt = 5;

    struct sembuf wait0, wait1, signal0, signal1;

    wait0.sem_num = 0;
    wait0.sem_op = -1;
    wait0.sem_flg = SEM_UNDO;

    wait1.sem_num = 1;
    wait1.sem_op = -1;
    wait1.sem_flg = SEM_UNDO;

    signal0.sem_num = 0;
    signal0.sem_op = 1;
    signal0.sem_flg = SEM_UNDO;

    signal1.sem_num = 1;
    signal1.sem_op = 1;
    signal1.sem_flg = SEM_UNDO;

    semid = semget(key1, 2 ,IPC_CREAT);

    semval = 1;
    semctl(semid,0, SETVAL, semval);
    semctl(semid,1, SETVAL, semval);

    int shmid;  // shared memory segment ID
    key_t key = 5678; // key for shared memory
    char *shm, *s; // pointers to shared memory
    allocateMemory(&shm);
    // if ((shmid = shmget(key, SHMSZ, IPC_CREAT | 0666)) < 0) {
    //     perror("shmget");
    //     exit(1);
    // }
    // if ((shm = (char*)shmat(shmid, NULL, 0)) == (char *) -1) {
    //     perror("shmat");
    //     exit(1);
    // }

    int childpid = fork();
    int messageSentFully = 1;
    int messageReceivedFully = 1;
    if(childpid == 0)
    {
        std::string fullMessage;
        while ( 1 )
        {
            puts("Reader wait1");
            semop(semid,&wait1,1);
            messageReceivedFully = 0;
            //semop(semid,&signal1,1);
            while( messageReceivedFully == 0)
            {
                puts("Reader wait0");
                semop(semid,&wait0,1);
                // if ( messageReceivedFully == 1)
                // {
                //  puts("\nReceived message:");
                // }
                char msg[SHMSZ] = {0};
                s = shm;
                for (int i = 0; i < SHMSZ; ++i)
                {
                    msg[i] = s[i];
                }
                fullMessage += msg;
                //puts(fullMessage.c_str());
                if ( msg[SHMSZ-1] == 0 )
                {
                    messageReceivedFully = 1;
                }
                else
                {
                    messageReceivedFully = 0;
                }
                puts("Reader signal0");
                semop(semid,&signal0,1);

            }
            puts("\nReceived message:");
            puts( fullMessage.c_str() );
            if (fullMessage == "quit\n")
            {
                break;
            }
            fullMessage = "";
            puts("Reader signal1");
            semop(semid,&signal1,1);
        }
        semctl(semid,0,IPC_RMID);
        printf("Semaphore removed from the System = %s\n", strerror(errno));
    }
    else
    {
        while(1)
        {
            puts("Writer wait1");
            semop(semid,&wait1,1);
            std::string message;
            puts("\nEnter message:");
            messageSentFully = 0;
            //semop(semid,&signal1, 1);
            while( messageSentFully == 0)
            {
                puts("Writer wait0");
                semop(semid, &wait0, 1);
                puts("Writer signal1");
                semop(semid, &signal1, 1);

                char msg[SHMSZ] = {0};
                int bytesRead = read( STDIN_FILENO, msg, SHMSZ );
                if (bytesRead < SHMSZ)
                {
                    messageSentFully = 1;
                }
                else
                {
                    messageSentFully = 0;
                }
                s = shm;
                for (int i = 0; i < SHMSZ; ++i)
                {
                    s[i] = msg[i];
                }

                message += msg;
                puts("Writer signal0");
                semop(semid, &signal0, 1);
            }
            message = "";
            if ( message == "quit\n")
            {
                break;
            }
            //semop(semid,&wait1,1);
            //semop(semid,&signal1,1);
        }
    }
    shmdt((void*)shm);
    return 0;
}