8216064: -XX:StartFlightRecording:settings= doesn't work properly

Reviewed-by: mgronlun

src/share/vm/jfr/dcmd/jfrDcmds.cpp

@@ -434,7 +434,13 @@ void JfrStartFlightRecordingDCmd::execute(DCmdSource source, TRAPS) {
 
   jobjectArray settings = NULL;
   if (_settings.is_set()) {
-    const int length = _settings.value()->array()->length();
+    int length = _settings.value()->array()->length();
+    if (length == 1) {
+      const char* c_str = _settings.value()->array()->at(0);
+      if (strcmp(c_str, "none") == 0) {
+        length = 0;
+      }
+    }
     settings = JfrJavaSupport::new_string_array(length, CHECK);
     assert(settings != NULL, "invariant");
     for (int i = 0; i < length; ++i) {

src/share/vm/jfr/jni/jfrJavaCall.cpp

@@ -184,7 +184,7 @@ void JfrJavaArguments::Parameters::copy(JavaCallArguments& args, TRAPS) const {
   }
 }
 
-JfrJavaArguments::JfrJavaArguments(JavaValue* result) : _result(result), _klass(NULL), _name(NULL), _signature(NULL), _array_length(0) {
+JfrJavaArguments::JfrJavaArguments(JavaValue* result) : _result(result), _klass(NULL), _name(NULL), _signature(NULL), _array_length(-1) {
   assert(result != NULL, "invariant");
 }
 
@@ -193,7 +193,7 @@ JfrJavaArguments::JfrJavaArguments(JavaValue* result, const char* klass_name, co
   _klass(NULL),
   _name(NULL),
   _signature(NULL),
-  _array_length(0) {
+  _array_length(-1) {
   assert(result != NULL, "invariant");
   if (klass_name != NULL) {
     set_klass(klass_name, CHECK);
@@ -210,7 +210,7 @@ JfrJavaArguments::JfrJavaArguments(JavaValue* result, const Klass* klass, const
   _klass(NULL),
   _name(NULL),
   _signature(NULL),
-  _array_length(0) {
+  _array_length(-1) {
   assert(result != NULL, "invariant");
   if (klass != NULL) {
     set_klass(klass);

src/share/vm/jfr/jni/jfrJavaSupport.cpp

@@ -166,7 +166,7 @@ static void create_object(JfrJavaArguments* args, JavaValue* result, TRAPS) {
 
   const int array_length = args->array_length();
 
-  if (array_length > 0) {
+  if (array_length >= 0) {
     array_construction(args, result, klass, array_length, CHECK);
   } else {
     object_construction(args, result, klass, THREAD);