CBXVirtualFileFileSystem::Open

public function Open($mode)
{
	$lmode = mb_strtolower(mb_substr($mode, 0, 1));
	$bExists = $this->IsExists();

	if (
		( $bExists && ($lmode !== 'x'))
		|| (!$bExists && ($lmode !== 'r'))
	)
		return fopen($this->GetPathWithNameEncoded(), $mode);

	return null;
}