/*
    unsharedmem.c

    Started by Jeff Ondich on 4/11/96
    Last modified on 4/7/10

    This program does not demonstrate how to use shared memory
    in Linux.
*/

#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>


char gSharedBuffer[100];


int main( void )
{
    pid_t pid;
    int status;

    /* Initialize the (un)shared memory. */
    strcpy( gSharedBuffer, "Mom, there's a singing moose outside!" );
    fprintf( stdout, "[Parent:%d before fork] Buffer: '%s'\n", getpid(), gSharedBuffer );

    /* Fork a child process */
    pid = fork();
    if( pid == -1 )
    {
        perror( "fork() failure" );
    }

    else if( pid != 0 )
    {
        fprintf( stdout, "[Parent:%d] Waiting...\n", getpid() );
        wait( &status );
        fprintf( stdout, "[Parent:%d] Done waiting.  Buffer: '%s'\n", getpid(), gSharedBuffer );
        fprintf( stdout, "[Parent:%d] Quitting\n", getpid() );
    }

    else
    {
        fprintf( stdout, "[Child:%d] Changing the buffer.\n", getpid() );
        strcpy( gSharedBuffer, "The moose is gone now." );
        fprintf( stdout, "[Child:%d] Buffer: '%s'\n", getpid(), gSharedBuffer );
        fprintf( stdout, "[Child:%d] Quitting\n", getpid() );
    }

    return 0;
}