with_current_dir.rs

fn with_current_dir<F, T>(path: &Path, f: F) -> std::io::Result<T>
        where F: FnOnce() -> T {
    let previous_dir = try!(current_dir());
    let rewind = || {
        match set_current_dir(&previous_dir) {
            Err(e) => {
                let _ = set_current_dir("/");
                let _ = writeln!(
                    &mut stderr(),
                    "couldn't chdir back to {:?}: {:?}",
                    previous_dir, e);
            }
            _ => ()
        }
    };

    try!(set_current_dir(path));
    let r: T = f.finally(rewind);

    Ok(r)
}