Make flag propagation automatic

Use reflection and tags to provide automatic conversion from
Config to flags. This makes adding new flags less error-prone,
skips flags using default values (easier to read), and makes
tests correctly use default flag values for test Configs.

Updates #3494

PiperOrigin-RevId: 328662070

1 files changed, 23 insertions, 5 deletions

diff --git a/pkg/sentry/watchdog/watchdog.go b/pkg/sentry/watchdog/watchdog.go
index 748273366..bbafb8b7f 100644
--- a/pkg/sentry/watchdog/watchdog.go
+++ b/pkg/sentry/watchdog/watchdog.go
@@ -96,15 +96,33 @@ const (
 	Panic
 )
 
+// Set implements flag.Value.
+func (a *Action) Set(v string) error {
+	switch v {
+	case "log", "logwarning":
+		*a = LogWarning
+	case "panic":
+		*a = Panic
+	default:
+		return fmt.Errorf("invalid watchdog action %q", v)
+	}
+	return nil
+}
+
+// Get implements flag.Value.
+func (a *Action) Get() interface{} {
+	return *a
+}
+
 // String returns Action's string representation.
-func (a Action) String() string {
-	switch a {
+func (a *Action) String() string {
+	switch *a {
 	case LogWarning:
-		return "LogWarning"
+		return "logWarning"
 	case Panic:
-		return "Panic"
+		return "panic"
 	default:
-		panic(fmt.Sprintf("Invalid action: %d", a))
+		panic(fmt.Sprintf("Invalid watchdog action: %d", *a))
 	}
 }