$OpenBSD: hack.fix,v 1.3 2001/01/28 23:41:44 niklas Exp $
$NetBSD: hack.fix,v 1.2 1995/03/23 08:30:17 cgd Exp $

/***** unido:net.games.hack / ab /  7:23 pm  Sep 13, 1985*/

Recently hack (1.0.3) crashed with core dumps during some good games.
The crashes occured in the onbill-routine. After investigating the core
dump I found that the shopkeeper's bill was still to be paid.  Normaly
if you leave a shop the bill will be cleared and onbill() would not
check it. But under certain conditions you can leave a shop without
clearing the bill. The conditions are:

     1. You have to rob a shop in order to make the shopkeeper
	follow you.

     2. After leaving the shop being followed by the shopkeeper
	you must return to the shop...

     3. ...and then leave the unguarded shop again.
	- The shopkeeper mustn't be present!

If you climb the stairs to the previous level, chances are that your
bill now contains much more items than allowed. If so the next call to
onbill() will dump the core.

Following is a context diff to fix the bug. Actually just the last hunk
does the fix [it deletes two lines which have been inserted in 1.0.3],
but I think the other fix was intended by the now deleted lines.

	Andreas

--
Andreas Bormann			ab@unido.UUCP
University of Dortmund		N 51 29' 05"   E 07 24' 42"
West Germany

------ the diff follows:

*** hack.shk.c.orig	Sun Aug  4 12:07:51 1985
--- hack.shk.c	Fri Sep 13 14:29:52 1985
***************
*** 133,139
  	/* Did we just leave a shop? */
  	if(u.uinshop &&
  	    (u.uinshop != roomno + 1 || shlevel != dlevel || !shopkeeper)) {
- 		u.uinshop = 0;
  		if(shopkeeper) {
  		    if(ESHK(shopkeeper)->billct) {
  			pline("Somehow you escaped the shop without paying!");

--- 133,138 -----
  	/* Did we just leave a shop? */
  	if(u.uinshop &&
  	    (u.uinshop != roomno + 1 || shlevel != dlevel || !shopkeeper)) {
  		if(shopkeeper) {
  		    if(ESHK(shopkeeper)->billct) {
  			if(inroom(shopkeeper->mx, shopkeeper->my) 
***************
*** 136,142
  		u.uinshop = 0;
  		if(shopkeeper) {
  		    if(ESHK(shopkeeper)->billct) {
! 			pline("Somehow you escaped the shop without paying!");
  			addupbill();
  			pline("You stole for a total worth of %ld zorkmids.",
  				total);

--- 135,143 -----
  	    (u.uinshop != roomno + 1 || shlevel != dlevel || !shopkeeper)) {
  		if(shopkeeper) {
  		    if(ESHK(shopkeeper)->billct) {
! 			if(inroom(shopkeeper->mx, shopkeeper->my) 
! 			    == u.uinshop - 1)	/* ab@unido */
! 			    pline("Somehow you escaped the shop without paying!");
  			addupbill();
  			pline("You stole for a total worth of %ld zorkmids.",
  				total);
***************
*** 149,154
  		    shopkeeper = 0;
  		    shlevel = 0;
  		}
  	}
  
  	/* Did we just enter a zoo of some kind? */

--- 150,156 -----
  		    shopkeeper = 0;
  		    shlevel = 0;
  		}
+ 		u.uinshop = 0;
  	}
  
  	/* Did we just enter a zoo of some kind? */
***************
*** 183,190
  		findshk(roomno);
  	    if(!shopkeeper) {
  		rooms[roomno].rtype = 0;
- 		u.uinshop = 0;
- 	    } else if(inroom(shopkeeper->mx, shopkeeper->my) != roomno) {
  		u.uinshop = 0;
  	    } else if(!u.uinshop){
  		if(!ESHK(shopkeeper)->visitct ||

--- 185,190 -----
  		findshk(roomno);
  	    if(!shopkeeper) {
  		rooms[roomno].rtype = 0;
  		u.uinshop = 0;
  	    } else if(!u.uinshop){
  		if(!ESHK(shopkeeper)->visitct ||
/* ---------- */