Lab 7b - Saving the world from EVIL part 2

In this lab, you will implement a multi-processing C program which will be used to execute the plan from your planner in lab 7a.

Compiling and running this lab requires AFS. This means you should ssh to one of the unix.qatar.cmu.edu machines to work, even if you have another linux machine (laptop, personal workstation, etc) on which you normally work.

This lab also requires that you have an X server running. Here's how you do this on several different machines:

• Linux If you're ssh'ing from a windowed environment in Linux, you already have an X server running. You can just add the -Y command line switch to ssh and everything should just work, e.g.
  
  ssh -Y unix.qatar.cmu.edu
• MacOS Run the X11 program that is commonly installed on all recent versions of OS X. This will give you a terminal window; ssh from this terminal window as described in the Linux section above, and it should work.
• Windows cluster machine - Before you start putty, start "X-Win32 9.4". This will pop a window and then disappear; that's fine, the X server is now running in the background. Then, in putty, before you connect, go down the options in the left bar to Connection - SSH - X11 and make sure the box that says "Enable X11 forwarding" is checked. Then connect to the server. Note that when you do something that will result in a window popping up on the windows machine, you'll get a warning box asking if you want to accept a connection from 127.0.0.1. You should accept the connection

The xeyes program. 50% cute, 50% creepy.

You can test your X server by running xeyes on unix.qatar.cmu.edu; if you see a window pop up on your computer with a pair of eyes in it, then you have configured things properly.

A library has been provided to you to interface with EVILcorp servers. The library comes in two parts: evil.h and libevil.a. Both can be found in afs at:

Library usage is documented via the comments in the evil.h header file, but here is a trivial program that, given a valid server key, connects to the libevil servers:

eviltest.c:

#include "evil.h"

int main(int argc, const char *argv[]) 
{ 
        // Note this won't work!  You need real key
        // values to hack into the servers!
        le_server_t *server = le_hack(1, 2, 3, 4); 

        // Connect to robot 1
        le_robot_t *rob = le_robot_connect(server, 1); 

        // Tell the robot to move forward 1 space
        le_robot_move(rob); 

        // Don't continue executing until the robot is
        // ready to take another command
        le_robot_wait_until_ready(rob); 
} 

You can compile this program as follows:

gcc -c -g -Wall -O0 -I/afs/qatar/usr/justinca/lab7 eviltest.c
gcc -o eviltest eviltest.o -L/afs/qatar/usr/justinca/lab7 -levil

The -I command line option says "include this directory in the places you look for files included using quotes". the -L command line options means "include this directory in the places you look for libraries", and the -levil command line option means "link this program together with the object files contained in a library named libevil.h

Your window into the server room.

If you successfully connect to the server and you have your X server running, you should see a window like the one on the right pop up. This window shows the current status of the server room, and will update as you command the robots.

The status window represents obstacles as light grey blocks, file locations as red bullseyes, and robot locations as green arrows. Note that your particular window will look different depending on the configuration of the server room to which you are connecting.