From 4d186571d543a9e52afc62920ac00b7ebe5a35bd Mon Sep 17 00:00:00 2001
From: Eugene Sandulenko
Date: Fri, 23 Aug 2019 16:31:09 +0200
Subject: HDB: Fix closed loops with laser beams

Nipun was able to construct such position in Map28 which led to a closed
loop and the game hung.

We're inserting a watchdog here now.
---
 engines/hdb/ai-bots.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'engines')

diff --git a/engines/hdb/ai-bots.cpp b/engines/hdb/ai-bots.cpp
index 33a15c08dd..ac4b24197c 100644
--- a/engines/hdb/ai-bots.cpp
+++ b/engines/hdb/ai-bots.cpp
@@ -1407,6 +1407,8 @@ void aiLaserAction(AIEntity *e) {
 
 	AIEntity *hit = e;
 	int moveOK = 0;
+	int moveCount = 0;
+
 	do {
 		int nx = hit->tileX;
 		int ny = hit->tileY;
@@ -1541,6 +1543,13 @@ void aiLaserAction(AIEntity *e) {
 					hit = NULL;
 			}
 		}
+
+		moveCount++;
+
+		// It is possible to set a configuration which leads to a closed loop.
+		// Thus, we're breaking it here
+		if (moveCount > 1000)
+			hit = NULL;
 	} while (hit && hit->type == AI_DIVERTER);
 }
 
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