'jack_ports.c' segfault

static const gchar *
get_matched_gtk_jack_port (const gchar   *string,
                           const gchar   *port_clicked,
                           jack_client_t *client)
{
    gchar *modded_string;
    gchar *dup;
    const gchar *string_return;
    gint i;

    string_return = NULL;
    modded_string = NULL;
    dup = NULL;
    dup = g_strdup (string);
    i = 0;

    while (dup[i])
    {
        if (dup[i] == ':')
        {
            modded_string = g_strndup (dup, i);

            if (g_strcmp0 (modded_string, port_clicked) == 0)
            {
                jack_port_t *jack_port;

                /* This is where it breaks it seems. */
                jack_port = jack_port_by_name (client, dup);// <----------------

                g_print ("Testing: %s\n", dup);

                string_return = jack_port_short_name (jack_port);

                jack_free (jack_port);

                break;
            }
        }

        i++;
    }

    g_free (modded_string);
    g_free (dup);

    if (string_return == NULL)
    {
        return NULL;
    }
    else
    {
        return string_return;
    }
}

static gint
create_audio_jack_ports_view (GtkListStore  *list_store,
                              GtkWidget     *view,
                              const gchar   *from_port_clicked,
                              const gchar   *to_port_clicked,
                              jack_client_t *client)
{
    GtkCellRenderer *renderer;
    GtkTreeViewColumn *column;
    GtkCellRenderer *toggle;
    GtkTreeViewColumn *toggle_column;
    jack_port_t *jack_port;
    gint i;
    gint j;
    const gchar **from_ports_array;
    const gchar **to_ports_array;
    GtkTreeIter iter;

    i = 0;
    renderer = gtk_cell_renderer_text_new ();
    column = gtk_tree_view_column_new_with_attributes (NULL,
                                                       renderer,
                                                       "text",
                                                       NULL);

    from_ports_array = jack_get_ports (client,
                                       NULL,
                                       JACK_DEFAULT_AUDIO_TYPE,
                                       JackPortIsOutput);

    to_ports_array = jack_get_ports (client,
                                     NULL,
                                     JACK_DEFAULT_AUDIO_TYPE,
                                     JackPortIsInput);

    while (to_ports_array[i])
    {
        i++;
    }

    GType types[i];

    for (j = 0; j <= i; j++)
    {
        if (j == 0)
        {
           types[j] = G_TYPE_STRING;
        }
        else
        {
            types[j] = G_TYPE_BOOLEAN;
        }
    }

    list_store = gtk_list_store_newv (i, types);

    i = 0;
    while (from_ports_array[i])
    {
        const gchar *jack_port_string;

        jack_port_string = get_matched_gtk_jack_port (from_ports_array[i],
                                                      from_port_clicked,
                                                      client);

        if (jack_port_string != NULL)
        {
            gtk_list_store_append (list_store, &iter);
            gtk_list_store_set (list_store,
                                &iter,
                                0,
                                jack_port_string,
                                -1);
        }

        i++;
    }

    jack_free (from_ports_array);
    gtk_tree_view_append_column (GTK_TREE_VIEW (view), column);

    i = 0;
    while (to_ports_array[i])
    {
        const gchar *jack_port_string;

        jack_port_string = get_matched_gtk_jack_port (to_ports_array[i],
                                                      to_port_clicked,
                                                      client);

        /*if (jack_port_string != NULL)
        {
            g_print ("%s\n", to_jack_port_string);

            toggle = gtk_cell_renderer_toggle_new ();

            gtk_cell_renderer_toggle_set_radio (GTK_CELL_RENDERER_TOGGLE (toggle),
                                                TRUE);

            column = gtk_tree_view_column_new_with_attributes (to_jack_port_string,
                                                               toggle,
                                                               NULL);

            gtk_tree_view_append_column (GTK_TREE_VIEW (view), toggle_column);
        }*/

        i++;
    }

    gtk_tree_view_set_model (GTK_TREE_VIEW (view), GTK_TREE_MODEL (list_store));

    g_object_unref (list_store);

    jack_free (to_ports_array);

    g_print ("From audio action success\n");

    return 0;
}