libct: add/use configs.HasHook

This allows to omit a call to c.currentOCIState (which can be somewhat
costly when there are many annotations) when the hooks of a given kind
won't be run.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libcontainer/configs/config.go

@@ -332,6 +332,19 @@ const (
 	Poststop HookName = "poststop"
 )
 
+// HasHook checks if config has any hooks with any given names configured.
+func (c *Config) HasHook(names ...HookName) bool {
+	if c.Hooks == nil {
+		return false
+	}
+	for _, h := range names {
+		if len(c.Hooks[h]) > 0 {
+			return true
+		}
+	}
+	return false
+}
+
 // KnownHookNames returns the known hook names.
 // Used by `runc features`.
 func KnownHookNames() []string {

libcontainer/container_linux.go

@@ -350,7 +350,7 @@ func (c *Container) start(process *Process) (retErr error) {
 
 	if process.Init {
 		c.fifo.Close()
-		if c.config.Hooks != nil {
+		if c.config.HasHook(configs.Poststart) {
 			s, err := c.currentOCIState()
 			if err != nil {
 				return err

libcontainer/criu_linux.go

@@ -1113,7 +1113,7 @@ func (c *Container) criuNotifications(resp *criurpc.CriuResp, process *Process,
 			return err
 		}
 	case "setup-namespaces":
-		if c.config.Hooks != nil {
+		if c.config.HasHook(configs.Prestart, configs.CreateRuntime) {
 			s, err := c.currentOCIState()
 			if err != nil {
 				return nil

libcontainer/process_linux.go

@@ -740,7 +740,7 @@ func (p *initProcess) start() (retErr error) {
 					return fmt.Errorf("error setting Intel RDT config for procHooks process: %w", err)
 				}
 			}
-			if len(p.config.Config.Hooks) != 0 {
+			if p.config.Config.HasHook(configs.Prestart, configs.CreateRuntime) {
 				s, err := p.container.currentOCIState()
 				if err != nil {
 					return err