GDBusMethodInvocation: add property return checks

Add some type checking for the values returned from async property
handling calls, similar in spirit to the type checking we do for normal
method calls.

https://bugzilla.gnome.org/show_bug.cgi?id=698375

diff --git a/gio/gdbusmethodinvocation.c b/gio/gdbusmethodinvocation.c
index ad19d9d..bd40aaf 100644 (file)
--- a/gio/gdbusmethodinvocation.c
+++ b/gio/gdbusmethodinvocation.c
@@ -418,6 +418,65 @@ g_dbus_method_invocation_return_value_internal (GDBusMethodInvocation *invocatio
       g_variant_type_free (type);
     }
 
+  /* property_info is only non-NULL if set that way from
+   * GDBusConnection, so this must be the case of async property
+   * handling on either 'Get', 'Set' or 'GetAll'.
+   */
+  if (invocation->property_info != NULL)
+    {
+      if (g_str_equal (invocation->method_name, "Get"))
+        {
+          GVariant *nested;
+
+          if (!g_variant_is_of_type (parameters, G_VARIANT_TYPE ("(v)")))
+            {
+              g_warning ("Type of return value for property 'Get' call should be '(v)' but got '%s'",
+                         g_variant_get_type_string (parameters));
+              goto out;
+            }
+
+          /* Go deeper and make sure that the value inside of the
+           * variant matches the property type.
+           */
+          g_variant_get (parameters, "(v)", &nested);
+          if (!g_str_equal (g_variant_get_type_string (nested), invocation->property_info->signature))
+            {
+              g_warning ("Value returned from property 'Get' call for '%s' should be '%s' but is '%s'",
+                         invocation->property_info->name, invocation->property_info->signature,
+                         g_variant_get_type_string (nested));
+            }
+          g_variant_unref (nested);
+        }
+
+      else if (g_str_equal (invocation->method_name, "GetAll"))
+        {
+          if (!g_variant_is_of_type (parameters, G_VARIANT_TYPE ("(a{sv})")))
+            {
+              g_warning ("Type of return value for property 'GetAll' call should be '(a{sv})' but got '%s'",
+                         g_variant_get_type_string (parameters));
+              goto out;
+            }
+
+          /* Could iterate the list of properties and make sure that all
+           * of them are actually on the interface and with the correct
+           * types, but let's not do that for now...
+           */
+        }
+
+      else if (g_str_equal (invocation->method_name, "Set"))
+        {
+          if (!g_variant_is_of_type (parameters, G_VARIANT_TYPE_UNIT))
+            {
+              g_warning ("Type of return value for property 'Set' call should be '()' but got '%s'",
+                         g_variant_get_type_string (parameters));
+              goto out;
+            }
+        }
+
+      else
+        g_assert_not_reached ();
+    }
+
   if (G_UNLIKELY (_g_dbus_debug_return ()))
     {
       _g_dbus_debug_print_lock ();