#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#define	MAXLINE		(80)
#define	FILE_ERR	(-1)
#define	PIPE_ERR	(-1)
#define	FORK_ERR	((pid_t)-1)
#define	FORK_CHLD	((pid_t)0)

#define SANITY(n,p)	if( ( n ) )			\
			{				\
			    perror( argv[ 0 ] );	\
			    ERRMSG( p );		\
			    _exit( EXIT_FAILURE );	\
			}
#define ERRMSG(p)	fprintf( stderr, "%s: " p "\n", argv[ 0 ] )

#define fprintf		( void ) fprintf

static char *ParMsg = "Hello, world!\n";
static char *SecretKey = "DieBrakDie";

int
main( int argc, char *argv[ ] )
{
    int      n, pfd[ 2 ];
    char     Line[ MAXLINE ];
    pid_t    Pid;

    if( argc != 1 )
	ERRMSG( "Unrecognized args" );

    SANITY( pipe( pfd ) == PIPE_ERR, "Can't create pipe" );
    SANITY( ( Pid = fork( ) ) == FORK_ERR, "Can't create child process" );

    if (Pid == FORK_CHLD)
    {
	/*
	 *	child closes writing end of pipe
	 */
	SANITY( close( pfd[ 1 ] ) == FILE_ERR, "Child can't close write end" );

	n = read( pfd[ 0 ], Line, MAXLINE );
	SANITY( n == FILE_ERR, "Child can't read pipe" );
	n = write( STDOUT_FILENO, Line, n );
	SANITY( n == FILE_ERR, "Child can't write stdout" );

	/*
	 *	child closes reading end of pipe
	 */
	SANITY( close( pfd[ 0 ] ) == FILE_ERR, "Child can't close read end" );
    }
    else
    {
	/*
	 *	parent closes reading end of pipe
	 */
	SANITY( close( pfd[ 0 ] ) == FILE_ERR, "Parent can't close read end" );

	n = write( pfd[ 1 ], ParMsg, strlen( ParMsg ) );
	SANITY( n == FILE_ERR, "Parent can't write pipe" );

	/*
	 *	parent closes writing end of pipe
	 */
	SANITY( close( pfd[ 1 ] ) == FILE_ERR, "Parent can't close write end" );
    }

    return EXIT_SUCCESS;

}

static void
xorencode( char s[ ], char key[ ], int n )
{
    int    i, j;
    char   c;

    for( i = 0, j = 0; i < n; i++ )
    {
        s[i] ^= key[j];
	j = ( j + 1 ) % ( strlen( key ) + 1 );
    }
}