//-------------------------------------------------------------------
//	trychannel.cpp
//
//	programmer: ALLAN CRUSE
//	written on: 08 NOV 2004
//-------------------------------------------------------------------

#include <stdio.h>	// for printf() 
#include <fcntl.h>	// for open() 
#include <stdlib.h>	// for exit() 
#include <unistd.h>	// for fork() 
#include <sys/wait.h>	// for wait()
#include "channels.h"	// for constants and functions


int main( int argc, char **argv )
{
	// parent process acquires the key to a new channel
	int	key = chan_make();
	if ( key < 0 ) { printf( "chan_make\n" ); exit(1); }

	// parent process then forks a child process
	switch ( fork() )
	{
	case -1: // fork failed 
		printf( "fork\n" ); 
		exit(1);

	case  0: // child process
		if ( chan_open( key ) < 0 )
			{ printf( "chan_open\n" ); exit(1); }
		else	{	
			char	buf[ 80 ] = "";
			int	nbytes = chan_pend( key, buf, 80 );
			if ( nbytes < 0 ) { printf( "chan_pend\n" ); exit(1); }
			printf( "%d bytes read ", nbytes );
			printf( "from channel %d \n", key );
			if ( nbytes > 0 ) write( 1, buf, nbytes );
			chan_shut( key );
			exit(0);
			}
	
	default: // parent process
		{
		char	msg[] = "Hello from parent\n";
		int	nbytes = chan_post( key, msg, sizeof( msg ) );
		if ( nbytes < 0 ) { printf( "chan_post\n" ); exit(1); }
	       	printf( "%d bytes written to channel %d \n", nbytes, key );	
		wait( NULL );
		chan_kill( key );
		exit(0);
		}
	}
}