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

3 files changed, 73 insertions, 19 deletions

diff --git a/pkg/refs/refcounter.go b/pkg/refs/refcounter.go
index d9d5e6bcb..57d8542b9 100644
--- a/pkg/refs/refcounter.go
+++ b/pkg/refs/refcounter.go
@@ -234,6 +234,39 @@ const (
 	LeaksLogTraces
 )
 
+// Set implements flag.Value.
+func (l *LeakMode) Set(v string) error {
+	switch v {
+	case "disabled":
+		*l = NoLeakChecking
+	case "log-names":
+		*l = LeaksLogWarning
+	case "log-traces":
+		*l = LeaksLogTraces
+	default:
+		return fmt.Errorf("invalid ref leak mode %q", v)
+	}
+	return nil
+}
+
+// Get implements flag.Value.
+func (l *LeakMode) Get() interface{} {
+	return *l
+}
+
+// String implements flag.Value.
+func (l *LeakMode) String() string {
+	switch *l {
+	case NoLeakChecking:
+		return "disabled"
+	case LeaksLogWarning:
+		return "log-names"
+	case LeaksLogTraces:
+		return "log-traces"
+	}
+	panic(fmt.Sprintf("invalid ref leak mode %q", *l))
+}
+
 // leakMode stores the current mode for the reference leak checker.
 //
 // Values must be one of the LeakMode values.
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))
 	}
 }
 
diff --git a/pkg/test/testutil/testutil.go b/pkg/test/testutil/testutil.go
index 42d79f5c2..b7f873392 100644
--- a/pkg/test/testutil/testutil.go
+++ b/pkg/test/testutil/testutil.go
@@ -138,20 +138,23 @@ func TestConfig(t *testing.T) *config.Config {
 	if dir, ok := os.LookupEnv("TEST_UNDECLARED_OUTPUTS_DIR"); ok {
 		logDir = dir + "/"
 	}
-	return &config.Config{
-		Debug:              true,
-		DebugLog:           path.Join(logDir, "runsc.log."+t.Name()+".%TIMESTAMP%.%COMMAND%"),
-		LogFormat:          "text",
-		DebugLogFormat:     "text",
-		LogPackets:         true,
-		Network:            config.NetworkNone,
-		Strace:             true,
-		Platform:           "ptrace",
-		FileAccess:         config.FileAccessExclusive,
-		NumNetworkChannels: 1,
-
-		TestOnlyAllowRunAsCurrentUserWithoutChroot: true,
-	}
+
+	// Only register flags if config is being used. Otherwise anyone that uses
+	// testutil will get flags registered and they may conflict.
+	config.RegisterFlags()
+
+	conf, err := config.NewFromFlags()
+	if err != nil {
+		panic(err)
+	}
+	// Change test defaults.
+	conf.Debug = true
+	conf.DebugLog = path.Join(logDir, "runsc.log."+t.Name()+".%TIMESTAMP%.%COMMAND%")
+	conf.LogPackets = true
+	conf.Network = config.NetworkNone
+	conf.Strace = true
+	conf.TestOnlyAllowRunAsCurrentUserWithoutChroot = true
+	return conf
 }
 
 // NewSpecWithArgs creates a simple spec with the given args suitable for use