core-bundle/src/Resources/contao/library/Contao/Folder.php
public function isUnprotected()
	{
		$path = $this->strFolder;

		do
		{
			if (file_exists($this->strRootDir . '/' . $path . '/.public'))
			{
				return true;
			}

			$path = \dirname($path);
		}
		while ($path != '.');

		return false;
	}
public function isUnprotected()
	{
		$path = $this->strFolder;

		do
		{
			if (file_exists($this->strRootDir . '/' . $path . '/.public'))
			{
				return true;
			}

			$path = \dirname($path);
		}
		while ($path != '.');

		return false;
	}
Check if the folder or any parent folder contains a .public file

@return bool