Function controller_command 

pub fn controller_command(
    name: &str,
    args: &[String],
    windows: bool,
    path: Option<&str>,
    pathext: Option<&str>,
) -> Option<Vec<String>>

The argv that starts the controller. Off Windows the bare name and the arguments (the OS finds the executable). On Windows the executable is resolved through PATHEXT here, and a .cmd/.bat goes through cmd.exe /c; None is CONTROLLER_NOT_FOUND.