Function short_name_8_3 

pub fn short_name_8_3(name: &str) -> String

Generate a DOS 8.3 short name for a long name ([MS-FSCC] §2.1.5.2.1 style): uppercased, invalid characters dropped, base truncated to 6 plus ~1, and a 3-character extension. Returns "" when name is already a valid 8.3 name (Windows then reports no short name).