MimeType::normalize

static function normalize($contentType)
{
	if (!is_string($contentType))
	{
		return 'application/octet-stream';
	}

	$ct = strtolower($contentType);
	$ct = str_replace(array("r", "n", ""), "", $ct);

	// We don't need attributes: image/jpeg; charset=ISO-8859-1
	$parts = explode(';', $ct);
	$ct = trim($parts[0]);

	if ($ct == '')
	{
		$ct = 'application/octet-stream';
	}
	elseif (strpos($ct, "excel") !== false)
	{
		$ct = "application/vnd.ms-excel";
	}
	elseif (strpos($ct, "word") !== false && strpos($ct, "vnd.openxmlformats") === false)
	{
		$ct = "application/msword";
	}
	elseif ($ct == 'image/pjpeg' || $ct == 'image/jpg')
	{
		$ct = 'image/jpeg';
	}

	return $ct;
}