mirror of https://github.com/k3s-io/k3s
99 lines
2.3 KiB
Go
99 lines
2.3 KiB
Go
// +build linux
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package systemd
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import (
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"context"
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"sync"
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systemdDbus "github.com/coreos/go-systemd/v22/dbus"
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dbus "github.com/godbus/dbus/v5"
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)
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var (
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dbusC *systemdDbus.Conn
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dbusMu sync.RWMutex
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dbusInited bool
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dbusRootless bool
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)
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type dbusConnManager struct{}
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// newDbusConnManager initializes systemd dbus connection manager.
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func newDbusConnManager(rootless bool) *dbusConnManager {
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dbusMu.Lock()
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defer dbusMu.Unlock()
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if dbusInited && rootless != dbusRootless {
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panic("can't have both root and rootless dbus")
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}
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dbusInited = true
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dbusRootless = rootless
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return &dbusConnManager{}
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}
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// getConnection lazily initializes and returns systemd dbus connection.
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func (d *dbusConnManager) getConnection() (*systemdDbus.Conn, error) {
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// In the case where dbusC != nil
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// Use the read lock the first time to ensure
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// that Conn can be acquired at the same time.
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dbusMu.RLock()
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if conn := dbusC; conn != nil {
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dbusMu.RUnlock()
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return conn, nil
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}
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dbusMu.RUnlock()
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// In the case where dbusC == nil
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// Use write lock to ensure that only one
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// will be created
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dbusMu.Lock()
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defer dbusMu.Unlock()
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if conn := dbusC; conn != nil {
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return conn, nil
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}
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conn, err := d.newConnection()
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if err != nil {
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return nil, err
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}
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dbusC = conn
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return conn, nil
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}
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func (d *dbusConnManager) newConnection() (*systemdDbus.Conn, error) {
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if dbusRootless {
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return newUserSystemdDbus()
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}
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return systemdDbus.NewWithContext(context.TODO())
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}
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// resetConnection resets the connection to its initial state
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// (so it can be reconnected if necessary).
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func (d *dbusConnManager) resetConnection(conn *systemdDbus.Conn) {
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dbusMu.Lock()
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defer dbusMu.Unlock()
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if dbusC != nil && dbusC == conn {
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dbusC.Close()
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dbusC = nil
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}
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}
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var errDbusConnClosed = dbus.ErrClosed.Error()
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// retryOnDisconnect calls op, and if the error it returns is about closed dbus
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// connection, the connection is re-established and the op is retried. This helps
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// with the situation when dbus is restarted and we have a stale connection.
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func (d *dbusConnManager) retryOnDisconnect(op func(*systemdDbus.Conn) error) error {
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for {
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conn, err := d.getConnection()
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if err != nil {
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return err
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}
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err = op(conn)
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if !isDbusError(err, errDbusConnClosed) {
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return err
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}
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d.resetConnection(conn)
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}
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}
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