[[ Bug 11039 ]] Throw error when changing behavior in behavior

livecodeali · montegoulding · commit 0ca8a5106888 · 2017-12-06T22:02:50.000+11:00
This patch prevents behavior scripts from changing their child's behavior. (cherry picked from commit 24e482a)
diff --git a/docs/notes/bugfix-11039.md b/docs/notes/bugfix-11039.md
@@ -0,0 +1 @@
+# Throw error when changing behavior from behavior script
diff --git a/engine/src/exec-interface-object.cpp b/engine/src/exec-interface-object.cpp
@@ -1698,10 +1698,20 @@ void MCObject::SetParentScript(MCExecContext& ctxt, MCStringRef new_parent_scrip
 	bool t_success;
 	t_success = true;
 
+	// If this object's parent script is on the script stack, it's an
+	// execution error
+	if (parent_script != nil &&
+	    parent_script -> GetParent() -> GetObject() != nil &&
+	    parent_script -> GetParent() -> GetObject() -> getscriptdepth() > 0)
+	{
+		ctxt . LegacyThrow(EE_PARENTSCRIPT_EXECUTING);
+		return;
+	}
+	
 	// MW-2008-11-02: [[ Bug ]] Setting the parentScript of an object to
 	//   empty should unset the parent script property and not throw an
 	//   error.
-	if (new_parent_script == nil || MCStringGetLength(new_parent_script) == 0)
+	if (MCStringIsEmpty(new_parent_script))
 	{
 		if (parent_script != NULL)
 			parent_script -> Release();
diff --git a/engine/src/executionerrors.h b/engine/src/executionerrors.h
@@ -2737,6 +2737,9 @@ enum Exec_errors
     
     // {EE-0896} graphic : too many points
     EE_GRAPHIC_TOOMANYPOINTS,
+
+	// {EE-0897} parentScript: can't change parent while parent script is executing
+	EE_PARENTSCRIPT_EXECUTING,
 };
 
 extern const char *MCexecutionerrors;
diff --git a/tests/lcs/core/engine/behavior.livecodescript b/tests/lcs/core/engine/behavior.livecodescript
@@ -0,0 +1,45 @@
+script "CoreEngineBehavior"
+/*
+Copyright (C) 2016 LiveCode Ltd.
+
+This file is part of LiveCode.
+
+LiveCode is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License v3 as published by the Free
+Software Foundation.
+
+LiveCode is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with LiveCode.  If not see <http://www.gnu.org/licenses/>.  */
+
+on _TestCyclicBehavior pStack
+   set the behavior of (the behavior of pStack) to pStack
+end _TestCyclicBehavior
+
+on TestCyclicBehavior
+   create stack "Behavior"
+   create stack
+   set the behavior of it to the long id of stack "Behavior"
+   TestAssertThrow "cycle in behavior script hierarchy throws", \
+      "_TestCyclicBehavior", the long id of me, 678, it
+end TestCyclicBehavior
+
+on TestInvalidBehaviorChange
+   local tScript
+   put "on changeBehavior" & return into tScript
+   put "set the behavior of me to the long id of stack" && quote & "NewBehavior" & quote & return after tScript
+   put "end changeBehavior" after tScript
+
+   create stack "NewBehavior"
+   create stack "Behavior"
+   set the script of it to tScript
+   
+   create stack
+   set the behavior of it to the long id of stack "Behavior"
+   TestAssertThrow "behavior change while parent script is executing throws", \
+      "changeBehavior", it, 895
+end TestInvalidBehaviorChange

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+# Throw error when changing behavior from behavior script`