Struct ExeReplaceGuard 

pub struct ExeReplaceGuard { /* private fields */ }

Windows can’t overwrite a running executable (the file is locked), but it CAN rename it. Parking the running exe under a .old name frees the original path so the cargo-dist installer’s Copy-Item succeeds; the parked file is removed on the next start.

The guard is plain filesystem logic so it is unit-tested on every platform; apply_with only activates it on Windows.

Implementations

impl ExeReplaceGuard

pub fn park(exe: &Path) -> Result<Self>

Rename exe aside. Replaces any stale artifact from a previous update first.

pub fn confirm_replaced(&self) -> Result<()>

After the installer ran: did a new binary land at the original path? If not, the installer wrote somewhere else and a restart would find nothing to exec — the caller must roll back.

pub fn rollback(self) -> Result<()>

Undo the park — the update failed and the worker keeps running the old version.