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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"encoding/json"
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"fmt"
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"sort"
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"strings"
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)
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// busctlName is one line of `busctl list --json`.
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type busctlName struct {
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Name string `json:"name"`
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PID *uint32 `json:"pid"`
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Process *string `json:"process"`
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User *string `json:"user"`
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Connection string `json:"connection"`
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Unit *string `json:"unit"`
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}
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// Name is one well-known name on a bus, with what holds it.
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type Name struct {
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Name string `json:"name"`
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PID uint32 `json:"pid,omitempty"`
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Process string `json:"process,omitempty"`
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User string `json:"user,omitempty"`
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Unit string `json:"unit,omitempty"`
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Connection string `json:"connection,omitempty"`
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}
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// Names is dbus_names's answer.
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type Names struct {
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Bus string `json:"bus"`
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Running []Name `json:"running"`
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ActivatableNotRunning []string `json:"activatable_not_running"`
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Connections int `json:"connections"`
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Cut bool `json:"cut,omitempty"`
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}
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// ParseNames reads `busctl list --json=short`: the well-known names running, the activatable names
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// that are not, and how many connections (unique names) the bus has.
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func ParseNames(bus, out string) (Names, error) {
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var raw []busctlName
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if err := json.Unmarshal([]byte(strings.TrimSpace(out)), &raw); err != nil {
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return Names{}, fmt.Errorf("busctl list answered what is not its JSON: %w", err)
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}
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n := Names{Bus: bus, Running: []Name{}, ActivatableNotRunning: []string{}}
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for _, r := range raw {
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switch {
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case r.Name == busName: // the bus itself, which busctl attributes to the service manager
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case strings.HasPrefix(r.Name, ":"):
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n.Connections++
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case r.Connection == "(activatable)" || r.PID == nil:
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n.ActivatableNotRunning = append(n.ActivatableNotRunning, r.Name)
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default:
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n.Running = append(n.Running, Name{Name: r.Name, PID: deref(r.PID), Process: derefS(r.Process),
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User: derefS(r.User), Unit: derefS(r.Unit), Connection: r.Connection})
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}
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}
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sort.Slice(n.Running, func(i, j int) bool { return n.Running[i].Name < n.Running[j].Name })
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sort.Strings(n.ActivatableNotRunning)
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if len(n.Running) > AnswerCap {
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n.Running, n.Cut = n.Running[:AnswerCap], true
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}
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if len(n.ActivatableNotRunning) > AnswerCap {
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n.ActivatableNotRunning, n.Cut = n.ActivatableNotRunning[:AnswerCap], true
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}
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return n, nil
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}
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// Names lists one bus's names as this account sees them.
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func (m *Machine) Names(ctx context.Context, bus string) (Names, error) {
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args, err := m.busArgs(bus)
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if err != nil {
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return Names{}, err
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}
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out, err := m.Run(ctx, "busctl", append(args, "--json=short", "--no-pager", "list")...)
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if err != nil {
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return Names{}, err
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}
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return ParseNames(orWord(bus, "system"), out)
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}
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func deref(p *uint32) uint32 {
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if p == nil {
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return 0
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}
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return *p
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}
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func derefS(p *string) string {
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if p == nil {
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return ""
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}
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return *p
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}
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func orWord(s, word string) string {
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if strings.TrimSpace(s) == "" {
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return word
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}
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return s
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}
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