Index: trunk/admin/install/install_lib.php
===================================================================
diff -u -r2561 -r3244
--- trunk/admin/install/install_lib.php	(.../install_lib.php)	(revision 2561)
+++ trunk/admin/install/install_lib.php	(.../install_lib.php)	(revision 3244)
@@ -843,4 +843,48 @@
 	return $submit_value == $value ? ' checked' : '';
 }
 
+	function StripDisallowed($string, $item_info)
+	{
+		$not_allowed = Array(	' ', '\\', '/', ':', '*', '?', '"', '<', '>', '|',
+		'~', '!', '@', '#', '$', '%', '^', '&', '(', ')',
+		'+', '=', '-', '{', '}', ']', '[', "'", ';', '.', ',');
+
+		$string = str_replace($not_allowed, '_', $string);
+		$string = preg_replace('/(_+)/', '_', $string);
+		$string = checkAutoFilename($string, $item_info);
+
+		return $string;
+	}
+
+	function checkAutoFilename($filename, $item_info)
+	{
+		// 'table' => 'Category', 'id_field' => 'CategoryId', 'title_field' => 'Name'
+		$item_id = $item_info['item_id'];
+		$prefix = GetTablePrefix();
+		$db =& inst_GetADODBConnection();
+
+		$sql = 'SELECT '.$item_info['id_field'].' FROM '.$prefix.$item_info['table'].' WHERE Filename = '.$db->qstr($filename);
+		$found_item_id = $db->GetOne($sql);
+		$has_page = preg_match('/(.*)_([\d]+)([a-z]*)$/', $filename, $rets);
+		if( ($found_item_id != $item_id) || $has_page ) // other category has same filename as ours OR we have filename, that ends with _number
+		{
+			$append = $found_item_id ? 'a' : '';
+			if($has_page)
+			{
+				$filename = $rets[1].'_'.$rets[2];
+				$append = $rets[3] ? $rets[3] : 'a';
+			}
+
+			$sql = 'SELECT '.$item_info['id_field'].' FROM '.$prefix.$item_info['table'].' WHERE (Filename = %s) AND ('.$item_info['id_field'].' != '.$item_id.')';
+			while ( $db->GetOne( sprintf($sql, $db->qstr($filename.$append)) ) > 0 )
+			{
+				if (substr($append, -1) == 'z') $append .= 'a';
+				$append = substr($append, 0, strlen($append) - 1) . chr( ord( substr($append, -1) ) + 1 );
+			}
+
+			return $filename.$append;
+		}
+
+		return $filename;
+	}
 ?>