jochen
7b5e1d3362
A live restart of the system bus during an upgrade hung every login on a workstation until a reboot. The module owns the bus's packages, declares the bus running with no restart or reload trigger, publishes only curated events (health, services, denials; never traffic) and serves tools to look at both buses.
104 lines
2.9 KiB
Go
104 lines
2.9 KiB
Go
package main
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import (
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"context"
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"github.com/godbus/dbus/v5"
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)
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const (
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busName = "org.freedesktop.DBus"
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busPath = "/org/freedesktop/DBus"
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)
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// systemBus is the machine's system bus as the watcher uses it, over its own private connection: the
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// bus driver's answers and its NameOwnerChanged signal, never another peer's messages.
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type systemBus struct {
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conn *dbus.Conn
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out chan NameChange
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}
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// DialSystemBus connects to the system bus as this account and listens for names changing owner.
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func DialSystemBus() (Bus, error) {
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conn, err := dbus.SystemBusPrivate()
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if err != nil {
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return nil, err
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}
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if err := conn.Auth(nil); err != nil {
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conn.Close()
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return nil, err
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}
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if err := conn.Hello(); err != nil {
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conn.Close()
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return nil, err
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}
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if err := conn.AddMatchSignal(dbus.WithMatchSender(busName), dbus.WithMatchInterface(busName),
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dbus.WithMatchMember("NameOwnerChanged")); err != nil {
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conn.Close()
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return nil, err
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}
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raw := make(chan *dbus.Signal, 256)
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conn.Signal(raw)
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b := &systemBus{conn: conn, out: make(chan NameChange, 256)}
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go func() {
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// The signal channel closes when the connection is lost; so does this one, which is how the
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// watcher learns the bus went away.
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defer close(b.out)
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for {
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select {
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case s, open := <-raw:
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if !open {
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return
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}
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if s.Name != busName+".NameOwnerChanged" || len(s.Body) != 3 {
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continue
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}
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name, _ := s.Body[0].(string)
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old, _ := s.Body[1].(string)
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nw, _ := s.Body[2].(string)
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b.out <- NameChange{Name: name, Old: old, New: nw}
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case <-conn.Context().Done():
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return
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}
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}
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}()
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return b, nil
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}
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func (b *systemBus) driver() dbus.BusObject { return b.conn.Object(busName, busPath) }
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// Ping asks the bus driver its id. Not org.freedesktop.DBus.Peer.Ping: dbus-broker's system policy
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// refuses that to an account that is not root, and logs the refusal as a denial.
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func (b *systemBus) Ping(ctx context.Context) error {
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var id string
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return b.driver().CallWithContext(ctx, busName+".GetId", 0).Store(&id)
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}
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func (b *systemBus) ID(ctx context.Context) (string, error) {
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var id string
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err := b.driver().CallWithContext(ctx, busName+".GetId", 0).Store(&id)
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return id, err
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}
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func (b *systemBus) PID(ctx context.Context, name string) (uint32, error) {
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var pid uint32
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err := b.driver().CallWithContext(ctx, busName+".GetConnectionUnixProcessID", 0, name).Store(&pid)
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return pid, err
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}
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func (b *systemBus) Names(ctx context.Context) ([]string, error) {
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var names []string
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err := b.driver().CallWithContext(ctx, busName+".ListNames", 0).Store(&names)
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return names, err
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}
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func (b *systemBus) Activatable(ctx context.Context) ([]string, error) {
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var names []string
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err := b.driver().CallWithContext(ctx, busName+".ListActivatableNames", 0).Store(&names)
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return names, err
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}
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func (b *systemBus) Changes() <-chan NameChange { return b.out }
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func (b *systemBus) Close() { b.conn.Close() }
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