Function take 

pub fn take(
    layout: &Layout,
    dest: &Path,
    daemon: Option<&Path>,
) -> Result<Taken, String>

Takes a backup of the node whose state directory is layout, into dest, in the shape verify reads and choir backup restore unpacks.

The same checks the flip-era pull script made, on the node’s own disk: the copied log must be a prefix-extension of the one already held here, contiguous from seq 0, and pass choir-node --verify-log when a daemon is there to run it; the policy archive must carry no key or credential; every bundle must verify. Everything is written into a sibling directory first and moved into place last, so a run cut short leaves the previous backup as it was.

Live is fine: the log is append-only, and a line the daemon was still writing fails the contiguity check and is refused, which is the right answer for a copy taken a moment too early.

Errors

Returns the sentence to print when the node’s files are missing, the log shrank or diverged from the backup already here, a secret is among the policy files, or a subprocess refused.