core-bundle/src/Resources/contao/library/Contao/Files.php
public function move_uploaded_file($strSource, $strDestination)
	{
		$this->validate($strSource, $strDestination);

		return move_uploaded_file($strSource, $this->strRootDir . '/' . $strDestination);
	}
public function move_uploaded_file($strSource, $strDestination)
	{
		$this->validate($strSource, $strDestination);

		return move_uploaded_file($strSource, $this->strRootDir . '/' . $strDestination);
	}
Move an uploaded file to a folder

@param string $strSource      The source file
@param string $strDestination The new file path

@return boolean True if the operation was successful