Range check option row index from lua in ScreenOptions:GetOptionRow to fix seg fault.

Docs/Changelog_sm5.txt

@@ -4,6 +4,10 @@ The StepMania 5 Changelog covers all post-sm-ssc changes. For a list of changes
 from StepMania 4 alpha 5 to sm-ssc v1.2.5, see Changelog_sm-ssc.txt.
 ________________________________________________________________________________
 
+2015/01/12
+----------
+* [ScreenOptions] GetNumRows function added. [kyzentun]
+
 2015/01/09
 ----------
 * [Sprite] SetStateProperties function added. [kyzentun]

Docs/Luadoc/Lua.xml

@@ -1442,6 +1442,7 @@
 			<Function name='AllAreOnLastRow'/>
 			<Function name='FocusedItemEndsScreen'/>
 			<Function name='GetCurrentRowIndex'/>
+			<Function name='GetNumRows'/>
 			<Function name='GetOptionRow'/>
 		</Class>
 		<Class base='ScreenOptions' name='ScreenPlayerOptions'>

Docs/Luadoc/LuaDocumentation.xml

@@ -4185,6 +4185,9 @@ save yourself some time, copy this for undocumented things:
 	<Function name='GetCurrentRowIndex' renamed='true' return='int' arguments='PlayerNumber pn'>
 		Returns the current row that player <code>pn</code> is on. (Was previously <code>GetCurrentRow</code>.)
 	</Function>
+	<Function name='GetNumRows' return='int' arguments=''>
+		Returns the number of rows on the screen.
+	</Function>
 	<Function name='GetOptionRow' return='OptionRow' arguments='int iRow'>
 		Returns the specified OptionRow.
 	</Function>

src/ScreenOptions.cpp

@@ -1352,13 +1352,21 @@ public:
 	static int FocusedItemEndsScreen( T* p, lua_State *L ) { lua_pushboolean( L, p->FocusedItemEndsScreen(Enum::Check<PlayerNumber>(L, 1)) ); return 1; }
 	static int GetCurrentRowIndex( T* p, lua_State *L ) { lua_pushnumber( L, p->GetCurrentRow(Enum::Check<PlayerNumber>(L, 1)) ); return 1; }
 	static int GetOptionRow( T* p, lua_State *L ) {
-		OptionRow* pOptRow = p->GetRow( IArg(1) );
+		int row_index= IArg(1);
+		// TODO:  Change row indices to be 1-indexed when breaking compatibility
+		// is allowed. -Kyz
+		if(row_index < 0 || row_index >= p->GetNumRows())
+		{
+			luaL_error(L, "Row index %d is invalid.", row_index);
+		}
+		OptionRow* pOptRow = p->GetRow(row_index);
 		if( pOptRow )
 			pOptRow->PushSelf(L);
 		else
 			lua_pushnil( L );
 		return 1;
 	}
+	DEFINE_METHOD(GetNumRows, GetNumRows());
    //static int SetOptionRowFromName( T* p, lua_State *L ) { p->SetOptionRowFromName( SArg(1) ); return 0; }
 
 	LunaScreenOptions()
@@ -1367,6 +1375,7 @@ public:
 		ADD_METHOD( FocusedItemEndsScreen );
 		ADD_METHOD( GetCurrentRowIndex );
 		ADD_METHOD( GetOptionRow );
+		ADD_METHOD( GetNumRows );
         //ADD_METHOD( SetOptionRowFromName );
 	}
 };

src/ScreenOptions.h

@@ -98,6 +98,7 @@ protected:
 	bool AllAreOnLastRow() const;
 	OptionRow* GetRow( int iRow ) const { return m_pRows[iRow]; }
         //void SetOptionRowFromName( const RString& nombre );
+	int GetNumRows() const { return static_cast<int>(m_pRows.size()); }
 
 protected:	// derived classes need access to these
 	enum Navigation { NAV_THREE_KEY, NAV_THREE_KEY_MENU, NAV_THREE_KEY_ALT, NAV_FIVE_KEY, NAV_TOGGLE_THREE_KEY, NAV_TOGGLE_FIVE_KEY };