o/h/ctlcmd: (wip) start work on snapctl tasks

Author: Rnfudge02

overlord/hookstate/ctlcmd/helpers.go

@@ -640,6 +640,68 @@ func setChangeAccessedAt(st *state.State, accessed time.Time, changeID string) {
 	st.Cache(key, accessed.UnixNano())
 }
 
+// changeStatus checks if the change is ready, if it is, it returns the status, otherwise st.Doing.
+func changeStatus(hctx *hookstate.Context, changeID string) (state.Change, error) {
+	callerSnapName := hctx.InstanceName()
+
+	st := hctx.State()
+	st.Lock()
+	defer st.Unlock()
+
+	chg := st.Change(changeID)
+
+	if chg == nil {
+		return state.Change{}, fmt.Errorf("change %q not found", changeID)
+	}
+
+	var initiatorSnapName string
+	err := chg.Get("initiated-by-snap", &initiatorSnapName)
+	if err != nil {
+		return state.Change{}, fmt.Errorf("could not find initiator attribute for change %q", changeID)
+	}
+
+	if initiatorSnapName != callerSnapName {
+		return state.Change{}, fmt.Errorf("change %q was initiated by another snap", changeID)
+	}
+
+	lastAccess := st.Cached(fmt.Sprintf("snapctl-%s-last-accessed", callerSnapName))
+	st.Cache(fmt.Sprintf("snapctl-%s-last-accessed", hctx.InstanceName()), time.Now().UnixNano())
+
+	// Compute how long to wait before checking the change status.
+	var toWait time.Duration
+	if lastAccess != nil {
+		lastAccessNano, ok := lastAccess.(int64)
+		if !ok {
+			return state.Change{}, fmt.Errorf("invalid last accessed time format for change %q", changeID)
+		}
+		toWait = 200*time.Millisecond - time.Since(time.Unix(0, lastAccessNano))
+	}
+
+	st.Unlock()
+
+	ready := chg.Ready()
+
+	if toWait <= 0 {
+		select {
+		case <-ready:
+			st.Lock()
+			return *chg, nil
+		default:
+			st.Lock()
+			return state.Change{}, nil
+		}
+	}
+
+	select {
+	case <-ready:
+		st.Lock()
+		return *chg, nil
+	case <-timeAfter(toWait):
+		st.Lock()
+		return state.Change{}, nil
+	}
+}
+
 // getAttribute unmarshals into result the value of the provided key from attributes map.
 // If the key does not exist, an error of type *NoAttributeError is returned.
 // The provided key may be formed as a dotted key path through nested maps.

overlord/hookstate/ctlcmd/tasks.go

@@ -0,0 +1,80 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) 2026 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package ctlcmd
+
+import (
+	"fmt"
+
+	"github.com/snapcore/snapd/i18n"
+	"github.com/snapcore/snapd/overlord/state"
+)
+
+type tasksCommand struct {
+	baseCommand
+	json bool
+}
+
+var shortTasksHelp = i18n.G(`Return a list of information associated with all change-ids.`)
+var longTasksHelp = i18n.G(`
+The tasks command is used to query the status of all change ids associated with
+snapctl commands running in asynchronous mode.
+
+$ snapctl tasks [--json]
+  0: successfully reported change information, regardless of state of change
+  1: any error (invalid change ID, permissions error)
+stdout: table of tasks, mirroring "snap tasks <change-id>" output
+stderr: empty for exit code 0. Contains relevant errors for exit code 1.
+`)
+
+func init() {
+	addCommand("tasks", shortTasksHelp, longTasksHelp, func() command {
+		return &tasksCommand{}
+	})
+}
+
+func (c *tasksCommand) Execute(args []string) error {
+	ctx, err := c.ensureContext()
+	if err != nil {
+		return err
+	}
+
+	if len(args) != 1 {
+		return fmt.Errorf("invalid number of arguments: expected 1, got %d", len(args))
+	}
+
+	c.json = c.flagSet.Lookup("json").Value.String() == "true"
+
+	ready, err := isReady(ctx, c.changeID)
+
+	if err != nil {
+		fmt.Fprintf(c.stderr, err.Error())
+		return &UnsuccessfulError{ExitCode: otherErrorExitCode}
+	}
+
+	if !ready.Ready() {
+		return &UnsuccessfulError{ExitCode: changeNotReadyExitCode}
+	}
+
+	if ready != state.DoneStatus {
+		return &UnsuccessfulError{ExitCode: changeUnsuccessfulExitCode}
+	}
+
+	return nil
+}