//forkExample.c
//John T. Rine
//October 23, 2011

#include <sys/types.h>
#include <stdlib.h>
#include<stdio.h>

#define CHILD 0

int globalTestVar = 0;

char *child(int *);
char *parent();
char *error();



int main(int argc, char **argv)
{
        char * procID = '\0';
        int localTestVar = 0;
        int *localTestVarPTR = NULL;
        localTestVarPTR = &localTestVar;

        pid_t pid;

        printf("Enter a global variable value\n");
        scanf("%d", &globalTestVar);

        printf("Enter a local variable value\n");
        scanf("%d", &localTestVar);


        pid = fork();

        //Error, failed to fork
        if (pid < CHILD) procID = error();
        //child
        else if (pid == CHILD) procID = child(localTestVarPTR);
        //parent
        else procID = parent();

        //Executed by both parent and child.
        printf("procID = %s\n", procID);
        printf("Global variable = %d\n", globalTestVar);
        printf("Local variable = %d\n", localTestVar);

}

char *child(int *localTestVarPtr)
{
        char *procID;
        procID = "Child Process: ";
        ++*localTestVarPtr;
        ++globalTestVar;
        return procID;
}

char *parent()
{
        char *procID;
        procID = "Parent Process:";
        return procID;
}

char *error()
{
        char *procID;
        procID = "Failed to fork";
        return procID;
}