notify: implement windows service status and error notifications (#7389)

* implement service status and error notifications

* adjust return of Error function

* configure accepts on status

* align windows with linux semantics

notify/notify_windows.go

@@ -14,16 +14,26 @@
 
 package notify
 
-import "golang.org/x/sys/windows/svc"
+import (
+	"log"
+	"strings"
+
+	"golang.org/x/sys/windows/svc"
+)
 
 // globalStatus store windows service status, it can be
 // use to notify caddy status.
 var globalStatus chan<- svc.Status
 
+// SetGlobalStatus assigns the channel through which status updates
+// will be sent to the SCM. This is typically provided by the service
+// handler when the service starts.
 func SetGlobalStatus(status chan<- svc.Status) {
 	globalStatus = status
 }
 
+// Ready notifies the SCM that the service is fully running and ready
+// to accept stop or shutdown control requests.
 func Ready() error {
 	if globalStatus != nil {
 		globalStatus <- svc.Status{
@@ -34,6 +44,8 @@ func Ready() error {
 	return nil
 }
 
+// Reloading notifies the SCM that the service is entering a transitional
+// state.
 func Reloading() error {
 	if globalStatus != nil {
 		globalStatus <- svc.Status{State: svc.StartPending}
@@ -41,6 +53,8 @@ func Reloading() error {
 	return nil
 }
 
+// Stopping notifies the SCM that the service is in the process of stopping.
+// This allows Windows to track the shutdown transition properly.
 func Stopping() error {
 	if globalStatus != nil {
 		globalStatus <- svc.Status{State: svc.StopPending}
@@ -48,8 +62,53 @@ func Stopping() error {
 	return nil
 }
 
-// TODO: not implemented
+// Status sends an arbitrary service state to the SCM based on a string
-func Status(_ string) error { return nil }
+// identifier of [svc.State].
+// The unknown states will be logged.
+func Status(name string) error {
+	if globalStatus == nil {
+		return nil
+	}
 
-// TODO: not implemented
+	var state svc.State
-func Error(_ error, _ int) error { return nil }
+	var accepts svc.Accepted
+	accepts = 0
+
+	switch strings.ToLower(name) {
+	case "stopped":
+		state = svc.Stopped
+	case "start_pending":
+		state = svc.StartPending
+	case "stop_pending":
+		state = svc.StopPending
+	case "running":
+		state = svc.Running
+		accepts = svc.AcceptStop | svc.AcceptShutdown
+	case "continue_pending":
+		state = svc.ContinuePending
+	case "pause_pending":
+		state = svc.PausePending
+	case "paused":
+		state = svc.Paused
+		accepts = svc.AcceptStop | svc.AcceptShutdown | svc.AcceptPauseAndContinue
+	default:
+		log.Printf("unknown state: %s", name)
+		return nil
+	}
+
+	globalStatus <- svc.Status{State: state, Accepts: accepts}
+	return nil
+}
+
+// Error notifies the SCM that the service is stopping due to a failure,
+// including a service-specific exit code.
+func Error(err error, code int) error {
+	if globalStatus != nil {
+		globalStatus <- svc.Status{
+			State:                   svc.StopPending,
+			ServiceSpecificExitCode: uint32(code),
+		}
+	}
+
+	return nil
+}