fn get_lockfile_path()

in xar/clean_xar_mounts/src/main.rs [302:360]

• 40 lines of code
• 2 McCabe index (conditional complexity)

fn get_lockfile_path(logger: &slog::Logger, mount: &MountedFilesystem) -> Vec<PathBuf> {
    // Strip off the dir the mountpoint is inside (only from a list of
    // valid prefixes).  If the mount isn't prefixed by our list, do
    // not unmount.
    let mount_suffix_opt = ["/mnt/xarfuse/", "/dev/shm/"]
        .iter()
        .filter_map(|candidate| {
            if mount.mountpoint.starts_with(candidate) {
                Some(&mount.mountpoint[candidate.len()..])
            } else {
                None
            }
        })
        .next();

    let mount_suffix = match mount_suffix_opt {
        Some(mnt) => mnt,
        None => {
            info!(
                logger,
                "Skipping unmount of {}, incorrect prefix", mount.mountpoint
            );
            return vec![];
        }
    };
    debug!(logger, "Mount suffix: {}", mount_suffix);

    // Mounts are of the form /prefix/uid-N/UUID-ns-NSID/... or
    // /prefix/uid-N/UUID-seed-SEED-ns-NSID/... -- we need to extract
    // the UUID portion.
    lazy_static! {
        static ref UUID_REGEX: Regex =
            Regex::new(r"^uid-\d+/([^/-]+)(?:-seed-(?:[^/]+))?-ns-([^-/]+)$").unwrap();
    }

    // Validate our filename looks like a mountpoint we care about,
    // and extract the UUID for the legacy lockfile.
    let captures = match UUID_REGEX.captures(&mount_suffix) {
        Some(captures) => captures,
        None => return vec![],
    };
    let uuid = captures.get(1).unwrap();

    // Look for the lockfile for the mountpoint; there are two cases,
    // one of just a lockfile.UUID (old style) and one of
    // lockfile.MOUNT_DIR (new style, which includes the UUID, seed,
    // and namespace).
    let mut lockfile_base = mount.chroot.clone();
    lockfile_base.push(&mount.mountpoint[1..]); // strip leading slash
    lockfile_base.set_file_name("lockfile");

    let mut old_lockfile = lockfile_base.clone();
    old_lockfile.set_extension(uuid.as_str());

    let mut new_lockfile = lockfile_base.clone();
    new_lockfile.set_extension(PathBuf::from(mount_suffix).file_name().unwrap());

    vec![new_lockfile, old_lockfile]
}