bestool-alertd 20.2.0

//! Bind spawned child processes' lifetime to the daemon's.
//!
//! Backups spawn helpers (`pg_basebackup`, `kopia`) as child processes. If the
//! daemon exits mid-backup — a clean stop, a crash, an OOM kill, or a self-update
//! restart — those children must go with it. On Linux systemd's cgroup tears the
//! whole unit down, so this is handled there. On Windows nothing ties a child to
//! its parent by default: a stranded `pg_basebackup` keeps streaming into the
//! stable staging dir, and the run the restarted daemon starts collides with it
//! (`could not create directory ...: File exists`). A job object with
//! kill-on-close makes every child die when the daemon process does.

/// Confine every process the daemon spawns to the daemon's own lifetime, so none
/// outlive it. A no-op on platforms where the service manager already guarantees
/// this (Linux under systemd).
pub fn confine_children() {
	#[cfg(windows)]
	imp::confine();
}

#[cfg(windows)]
mod imp {
	use tracing::{info, warn};
	use win32job::{ExtendedLimitInfo, Job};

	pub fn confine() {
		let mut info = ExtendedLimitInfo::new();
		info.limit_kill_on_job_close();

		let job = match Job::create_with_limit_info(&info) {
			Ok(job) => job,
			Err(err) => {
				warn!(
					"could not create the job object to confine backup children ({err}); \
					 they may outlive a daemon restart"
				);
				return;
			}
		};

		if let Err(err) = job.assign_current_process() {
			warn!(
				"could not assign the daemon to its job object ({err}); \
				 backup children may outlive a daemon restart"
			);
			return;
		}

		// Keep the handle open for the daemon's whole life: closing it is what fires
		// the kill, so it must outlive every backup. `into_handle` yields the raw
		// handle without running `Drop` (which would close it here and now).
		let _ = job.into_handle();
		info!("confined child processes to the daemon's lifetime");
	}
}