core-bundle/src/Resources/contao/library/Contao/Files.php
public function chmod($strFile, $varMode)
	{
		$this->validate($strFile);

		return chmod($this->strRootDir . '/' . $strFile, $varMode);
	}
public function chmod($strFile, $varMode)
	{
		$this->validate($strFile);

		return chmod($this->strRootDir . '/' . $strFile, $varMode);
	}
Change the file mode

@param string $strFile The file name
@param mixed  $varMode The new file mode

@return boolean True if the operation was successful