From e939d6885d293020469840eef43a0ad42f902a8e Mon Sep 17 00:00:00 2001
From: Edoardo Prezioso <edo88@email.it>
Date: Sat, 5 Sep 2015 23:58:02 +0200
Subject: [PATCH] - Fixed a crash in ACS strlen parsing with invalid argument.

---
 src/p_acs.cpp | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/p_acs.cpp b/src/p_acs.cpp
index b703b87dd..54f9fa658 100644
--- a/src/p_acs.cpp
+++ b/src/p_acs.cpp
@@ -8880,7 +8880,22 @@ scriptwait:
 			break;
 
 		case PCD_STRLEN:
-			STACK(1) = SDWORD(strlen(FBehavior::StaticLookupString (STACK(1))));
+			{
+				const char *str = FBehavior::StaticLookupString(STACK(1));
+				if (str != NULL)
+				{
+					STACK(1) = SDWORD(strlen(str));
+					break;
+				}
+
+				static bool StrlenInvalidPrintedAlready = false;
+				if (!StrlenInvalidPrintedAlready)
+				{
+					Printf(PRINT_BOLD, "Warning: ACS function strlen called with invalid string argument.\n");
+					StrlenInvalidPrintedAlready = true;
+				}
+				STACK(1) = 0;
+			}
 			break;
 
 		case PCD_GETCVAR: