[gst-debugger] common: fix serialization

[Marcin Kolny <mkolny src gnome org>]

commit 3b6c5d75bebe5d9aac2119ab475eda3ddf0b87ae
Author: Marcin Kolny <marcin kolny gmail com>
Date:   Fri Oct 20 12:37:55 2017 +0100

    common: fix serialization
    
    GStreamer registers some types as fundamental (eg GstFraction)
    but we cannot handle them as GLib fundamental types

 src/common/serializer.c                            |    2 +-
 .../gvalue-converter/gvalue_unknown.cpp            |   15 +++++++++++++--
 2 files changed, 14 insertions(+), 3 deletions(-)
---
diff --git a/src/common/serializer.c b/src/common/serializer.c
index 06b2fd5..3793f26 100644
--- a/src/common/serializer.c
+++ b/src/common/serializer.c
@@ -13,7 +13,7 @@ gchar * g_value_serialize (GValue * value, GType * type, InternalGType * interna
 {
   GValue tmp = G_VALUE_INIT;
 
-  if (G_TYPE_IS_FUNDAMENTAL (value->g_type)) {
+  if (G_TYPE_IS_FUNDAMENTAL (value->g_type) && value->g_type < G_TYPE_RESERVED_USER_FIRST) {
     *type = value->g_type;
     *internal_type = INTERNAL_GTYPE_FUNDAMENTAL;
     return gst_value_serialize (value);
diff --git a/src/gst-debugger/gvalue-converter/gvalue_unknown.cpp 
b/src/gst-debugger/gvalue-converter/gvalue_unknown.cpp
index d111ed1..896f1b2 100644
--- a/src/gst-debugger/gvalue-converter/gvalue_unknown.cpp
+++ b/src/gst-debugger/gvalue-converter/gvalue_unknown.cpp
@@ -17,8 +17,19 @@ GValueUnknown::GValueUnknown(GValue *gobj)
 
 std::string GValueUnknown::to_string() const
 {
-       GstUnknownType *unknown_type = (GstUnknownType*)g_value_get_boxed(g_value);
-       return _("unsupported type: ") + std::string(unknown_type->type_name);
+    std::string type_name;
+    if (!G_VALUE_HOLDS_BOXED(g_value))
+    {
+        type_name = "INVALID";
+        g_warning("GValueUnknown should hold boxed type!");
+    }
+    else
+    {
+        GstUnknownType *unknown_type = (GstUnknownType*)g_value_get_boxed(g_value);
+        type_name = unknown_type->type_name;
+    }
+
+    return _("unsupported type: ") + type_name;
 }
 
 Gtk::Widget* GValueUnknown::create_widget()