//go:build linux

package host

import (
	"context"
	"net"
	"os/exec"

	"golang.org/x/sys/unix"
)

func dialDBReadWorker(ctx context.Context) (net.Conn, error) {
	var d net.Dialer
	return d.DialContext(ctx, "unix", dbReadSocketPath)
}

// dbReadUnits lists carlos-dbread@ units, readable without privilege.
func dbReadUnits(ctx context.Context) (int, error) {
	out, err := exec.CommandContext(ctx, "systemctl", "list-units", "--all", "--plain", "--no-legend", "--no-pager", "carlos-dbread@*.service").Output()
	if err != nil {
		return 0, err
	}
	return countDBReadUnits(string(out)), nil
}

// varTmpFree is the filesystem holding /var/tmp, where every worker's
// private /var/tmp lives.
func varTmpFree() (uint64, uint64, error) {
	var st unix.Statfs_t
	if err := unix.Statfs("/var/tmp", &st); err != nil {
		return 0, 0, err
	}
	return st.Bavail * uint64(st.Bsize), st.Blocks * uint64(st.Bsize), nil
}