internal/kobject: improve error JSON representation

This is now usable by internal/report.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/kobject/kobject.go

@@ -9,6 +9,7 @@ import (
 	"strconv"
 	"sync"
 
+	"hakurei.app/internal/report"
 	"hakurei.app/internal/uevent"
 )
 
@@ -29,9 +30,9 @@ const (
 // Object represents a kernel object.
 type Object struct {
 	// Origin of the object.
-	State int `json:"-"`
+	State int `json:"state,omitempty"`
 	// Set by [uevent.KOBJ_OFFLINE] and [uevent.KOBJ_ONLINE].
-	Offline bool
+	Offline bool `json:"offline,omitempty"`
 
 	// alloc_uevent_skb: devpath
 	DevPath string `json:"devpath"`
@@ -48,11 +49,11 @@ type Object struct {
 	Env map[string]string `json:"env"`
 }
 
-// Clone returns a copy of o.
-func (o *Object) Clone() Object {
+// Clone returns the address of a copy of o.
+func (o *Object) Clone() *Object {
 	v := *o
 	v.Env = maps.Clone(o.Env)
-	return v
+	return &v
 }
 
 // GoString returns compound literal for the underlying value.
@@ -194,77 +195,94 @@ func (s *State) Range(ctx context.Context, f func(o *Object) bool) {
 	}
 }
 
-// UnexpectedColdbootError is reported by [State.Consume] for a coldboot event
-// with action other than the expected [uevent.KOBJ_ADD].
-type UnexpectedColdbootError Event
-
-func (e UnexpectedColdbootError) Error() string {
-	return "unexpected " + e.Action.String() + " coldboot event"
+// An EventError describes a malformed or inconsistent [Event].
+type EventError struct {
+	Kind int     `json:"fault"`
+	E    Event   `json:"event"`
+	O    *Object `json:"object,omitempty"`
 }
 
-// DuplicateAddError is reported by [State.Consume] for a [uevent.KOBJ_ADD]
-// event on a still-existing entry that was not the result of a coldboot.
-type DuplicateAddError Event
+var _ report.RepresentableError = EventError{}
 
-func (e DuplicateAddError) Error() string {
-	return "duplicate add event on devpath " + strconv.Quote(e.DevPath)
-}
+func (EventError) Representable() {}
 
-// TargetError is reported by [State.Consume] for an event on a nonexistent
-// entry. This is generally only possible before coldboot completes.
-type TargetError Event
+const (
+	// EUnexpectedColdboot is reported for a coldboot event with action other
+	// than the expected [uevent.KOBJ_ADD].
+	EUnexpectedColdboot = iota
+	// EDuplicateAdd is reported for a [uevent.KOBJ_ADD] event on a
+	// still-existing entry that was not the result of a coldboot.
+	EDuplicateAdd
+	// EBadTarget is reported for an event on a nonexistent [Object]. This is
+	// generally only possible before coldboot completes.
+	EBadTarget
+	// ERemoveState is reported for a [uevent.KOBJ_REMOVE] event targeting an
+	// entry in a state other than [StateColdboot] and [StateNew].
+	ERemoveState
+	// EUnexpectedOffline is reported for a [uevent.KOBJ_OFFLINE] or
+	// [uevent.KOBJ_ONLINE] event targeting an already offline or online object.
+	EUnexpectedOffline
+	// EBindState is reported for a [uevent.KOBJ_BIND] event targeting an entry
+	// in a state other than [StateColdboot] and [StateNew].
+	EBindState
+	// EUnbindState is reported for a [uevent.KOBJ_UNBIND] event targeting an
+	// entry in a state other than [StateBound].
+	EUnbindState
+	// EMalformedMove is reported for a [uevent.KOBJ_MOVE] event missing the
+	// DEVPATH_OLD environment variable.
+	EMalformedMove
+)
 
-func (e TargetError) Error() string {
-	return "unexpected " + e.Action.String() +
-		" event on devpath " + strconv.Quote(e.DevPath)
-}
+func (e EventError) Error() string {
+	switch e.Kind {
+	case EUnexpectedColdboot:
+		return "unexpected " + e.E.Action.String() + " coldboot event"
+	case EDuplicateAdd:
+		return "duplicate add event on devpath " + strconv.Quote(e.E.DevPath)
+	case EBadTarget:
+		return "unexpected " + e.E.Action.String() + " event on devpath " +
+			strconv.Quote(e.E.DevPath)
+	case ERemoveState:
+		if e.O == nil {
+			return "invalid remove event error"
+		}
+		return "remove event targeting devpath " + strconv.Quote(e.E.DevPath) +
+			" in state " + strconv.Itoa(e.O.State)
+	case EUnexpectedOffline:
+		if e.O == nil {
+			return "invalid unexpected offline error"
+		}
+		if e.O.Offline {
+			return "offline event targeting devpath " + strconv.Quote(e.E.DevPath)
+		}
+		return "online event targeting devpath " + strconv.Quote(e.E.DevPath)
+	case EBindState:
+		if e.O == nil {
+			return "invalid bind state error"
+		}
+		return "bind event targeting devpath " + strconv.Quote(e.E.DevPath) +
+			" in state " + strconv.Itoa(e.O.State)
+	case EUnbindState:
+		if e.O == nil {
+			return "invalid unbind state error"
+		}
+		return "unbind event targeting devpath " + strconv.Quote(e.E.DevPath) +
+			" in state " + strconv.Itoa(e.O.State)
+	case EMalformedMove:
+		return "move event targeting devpath " + strconv.Quote(e.E.DevPath) +
+			" missing DEVPATH_OLD"
 
-// RemoveStateError is reported by [State.Consume] for a [uevent.KOBJ_REMOVE]
-// event targeting an entry in a state other than [StateColdboot] and [StateNew].
-type RemoveStateError Object
-
-func (e RemoveStateError) Error() string {
-	return "remove event targeting devpath " + strconv.Quote(e.DevPath) +
-		" in state " + strconv.Itoa(e.State)
-}
-
-// BindStateError is reported by [State.Consume] for a [uevent.KOBJ_BIND] event
-// targeting an entry in a state other than [StateColdboot] and [StateNew].
-type BindStateError Object
-
-func (e BindStateError) Error() string {
-	return "bind event targeting devpath " + strconv.Quote(e.DevPath) +
-		" in state " + strconv.Itoa(e.State)
-}
-
-// UnbindStateError is reported by [State.Consume] for a [uevent.KOBJ_UNBIND]
-// event targeting an entry in a state other than [StateBound].
-type UnbindStateError Object
-
-func (e UnbindStateError) Error() string {
-	return "unbind event targeting devpath " + strconv.Quote(e.DevPath) +
-		" in state " + strconv.Itoa(e.State)
-}
-
-// MalformedMoveError is reported by [State.Consume] for a [uevent.KOBJ_MOVE]
-// event missing the DEVPATH_OLD environment variable.
-type MalformedMoveError Event
-
-func (e MalformedMoveError) Error() string {
-	return "move event targeting devpath " + strconv.Quote(e.DevPath) +
-		" missing DEVPATH_OLD"
-}
-
-// UnexpectedOfflineError is reported by [State.Consume] for a
-// [uevent.KOBJ_OFFLINE] or [uevent.KOBJ_ONLINE] event targeting an already
-// offline or online object.
-type UnexpectedOfflineError Object
-
-func (e UnexpectedOfflineError) Error() string {
-	if e.Offline {
-		return "offline event targeting devpath " + strconv.Quote(e.DevPath)
+	default:
+		return "invalid event error kind " + strconv.Itoa(e.Kind)
 	}
-	return "online event targeting devpath " + strconv.Quote(e.DevPath)
+}
+
+// NewError returns a new [EventError] for e and o.
+func (e *Event) NewError(kind int, o *Object) error {
+	if o != nil {
+		o = o.Clone()
+	}
+	return EventError{kind, e.Clone(), o}
 }
 
 // processEvent merges an event into s.
@@ -274,7 +292,7 @@ func (s *State) processEvent(e *Event) {
 
 	coldboot := e.Synth != nil
 	if e.Action != uevent.KOBJ_ADD && coldboot {
-		s.reportErr(UnexpectedColdbootError(e.Clone()))
+		s.reportErr(e.NewError(EUnexpectedColdboot, nil))
 		return
 	}
 
@@ -282,7 +300,7 @@ func (s *State) processEvent(e *Event) {
 	case uevent.KOBJ_ADD:
 		if e.Synth == nil {
 			if o, ok := s.uevent[e.DevPath]; ok {
-				s.reportErr(DuplicateAddError(e.Clone()))
+				s.reportErr(e.NewError(EDuplicateAdd, o))
 				o.merge(e.Env)
 				s.dispatchIter(o)
 				return
@@ -299,10 +317,10 @@ func (s *State) processEvent(e *Event) {
 
 	case uevent.KOBJ_REMOVE:
 		if o, ok := s.uevent[e.DevPath]; !ok {
-			s.reportErr(TargetError(e.Clone()))
+			s.reportErr(e.NewError(EBadTarget, nil))
 			return
 		} else if o.State != StateColdboot && o.State != StateNew {
-			s.reportErr(RemoveStateError(o.Clone()))
+			s.reportErr(e.NewError(ERemoveState, o))
 		}
 		delete(s.uevent, e.DevPath)
 		return
@@ -310,7 +328,7 @@ func (s *State) processEvent(e *Event) {
 	case uevent.KOBJ_CHANGE:
 		o, ok := s.uevent[e.DevPath]
 		if !ok {
-			s.reportErr(TargetError(e.Clone()))
+			s.reportErr(e.NewError(EBadTarget, nil))
 			// this suffers from the coldboot race window similar to KOBJ_MOVE,
 			// however this action combines driver-specific and change-specific
 			// environment variables and combines them with environment
@@ -333,11 +351,11 @@ func (s *State) processEvent(e *Event) {
 	case uevent.KOBJ_MOVE:
 		var o *Object
 		if old, ok := e.Env["DEVPATH_OLD"]; !ok {
-			s.reportErr(MalformedMoveError(e.Clone()))
+			s.reportErr(e.NewError(EMalformedMove, nil))
 			// not reached
 			o = e.makeColdboot()
 		} else if o, ok = s.uevent[old]; !ok {
-			s.reportErr(TargetError(e.Clone()))
+			s.reportErr(e.NewError(EBadTarget, nil))
 			// this generally happens during coldboot, dropping the event here
 			// may cause inconsistent state if the coldboot event for this
 			// object was generated before the bind event
@@ -356,14 +374,14 @@ func (s *State) processEvent(e *Event) {
 	case uevent.KOBJ_ONLINE:
 		o, ok := s.uevent[e.DevPath]
 		if !ok {
-			s.reportErr(TargetError(e.Clone()))
+			s.reportErr(e.NewError(EBadTarget, nil))
 			// coldboot race window similar to an unexpected KOBJ_MOVE
 			o = e.makeColdboot()
 			s.uevent[e.DevPath] = o
 			o.merge(e.Env)
 		}
 		if !o.Offline {
-			s.reportErr(UnexpectedOfflineError(o.Clone()))
+			s.reportErr(e.NewError(EUnexpectedOffline, o))
 		}
 		o.Offline = false
 		s.dispatchIter(o)
@@ -372,14 +390,14 @@ func (s *State) processEvent(e *Event) {
 	case uevent.KOBJ_OFFLINE:
 		o, ok := s.uevent[e.DevPath]
 		if !ok {
-			s.reportErr(TargetError(e.Clone()))
+			s.reportErr(e.NewError(EBadTarget, nil))
 			// coldboot race window similar to an unexpected KOBJ_MOVE
 			o = e.makeColdboot()
 			s.uevent[e.DevPath] = o
 			o.merge(e.Env)
 		}
 		if o.Offline {
-			s.reportErr(UnexpectedOfflineError(o.Clone()))
+			s.reportErr(e.NewError(EUnexpectedOffline, o))
 		}
 		o.Offline = true
 		s.dispatchIter(o)
@@ -388,13 +406,13 @@ func (s *State) processEvent(e *Event) {
 	case uevent.KOBJ_BIND:
 		o, ok := s.uevent[e.DevPath]
 		if !ok {
-			s.reportErr(TargetError(e.Clone()))
+			s.reportErr(e.NewError(EBadTarget, nil))
 			// coldboot race window similar to an unexpected KOBJ_MOVE
 			o = e.makeColdboot()
 			s.uevent[e.DevPath] = o
 		}
 		if o.State != StateColdboot && o.State != StateNew {
-			s.reportErr(BindStateError(o.Clone()))
+			s.reportErr(e.NewError(EBindState, o))
 		}
 		o.State = StateBound
 		o.merge(e.Env)
@@ -404,13 +422,13 @@ func (s *State) processEvent(e *Event) {
 	case uevent.KOBJ_UNBIND:
 		o, ok := s.uevent[e.DevPath]
 		if !ok {
-			s.reportErr(TargetError(e.Clone()))
+			s.reportErr(e.NewError(EBadTarget, nil))
 			// coldboot race window similar to an unexpected KOBJ_MOVE, but does
 			// not result in inconsistent state if dropped
 			return
 		}
 		if o.State != StateBound {
-			s.reportErr(UnbindStateError(o.Clone()))
+			s.reportErr(e.NewError(EUnbindState, o))
 		}
 		o.State = StateNew
 		o.Driver = ""
@@ -423,7 +441,7 @@ func (s *State) processEvent(e *Event) {
 	}
 }
 
-// BadSequenceError is reported by [State.Consume] for an unexpected SEQNUM.
+// BadSequenceError is reported for an unexpected SEQNUM.
 type BadSequenceError struct{ Got, Want uint64 }
 
 func (e BadSequenceError) Error() string {