Nuke redundant signatures from introspection data + fixup error returns

Make g_dbus_message_new_method_error() be a varadic function and also
provide _valist() and _literal() variants. Use the varadic function to
provide more detail when generating errors.

12 files changed, 203 insertions, 117 deletions

diff --git a/docs/reference/gdbus/gdbus-standalone-sections.txt b/docs/reference/gdbus/gdbus-standalone-sections.txt
index 09fd542..1443065 100644
--- a/docs/reference/gdbus/gdbus-standalone-sections.txt
+++ b/docs/reference/gdbus/gdbus-standalone-sections.txt
@@ -32,19 +32,15 @@ g_credentials_to_string
 g_credentials_has_unix_user
 g_credentials_get_unix_user
 g_credentials_set_unix_user
-g_credentials_unset_unix_user
 g_credentials_has_unix_group
 g_credentials_get_unix_group
 g_credentials_set_unix_group
-g_credentials_unset_unix_group
 g_credentials_has_unix_process
 g_credentials_get_unix_process
 g_credentials_set_unix_process
-g_credentials_unset_unix_process
 g_credentials_has_windows_user
 g_credentials_get_windows_user
 g_credentials_set_windows_user
-g_credentials_unset_windows_user
 <SUBSECTION Standard>
 G_CREDENTIALS
 G_IS_CREDENTIALS
@@ -125,10 +121,12 @@ GDBusMessageHeaderField
 GDBusMessage
 GDBusMessageClass
 g_dbus_message_new
+g_dbus_message_new_signal
 g_dbus_message_new_method_call
-g_dbus_message_new_method_error
 g_dbus_message_new_method_reply
-g_dbus_message_new_signal
+g_dbus_message_new_method_error
+g_dbus_message_new_method_error_valist
+g_dbus_message_new_method_error_literal
 g_dbus_message_print
 g_dbus_message_get_type
 g_dbus_message_set_type
diff --git a/gdbus/gdbusconnection.c b/gdbus/gdbusconnection.c
index 9f625db..dfb2745 100644
--- a/gdbus/gdbusconnection.c
+++ b/gdbus/gdbusconnection.c
@@ -2966,9 +2966,9 @@ invoke_get_property_in_idle_cb (gpointer _data)
       g_assert (error != NULL);
 
       dbus_error_name = g_dbus_error_encode_gerror (error);
-      reply = g_dbus_message_new_method_error (data->message,
-                                               dbus_error_name,
-                                               error->message);
+      reply = g_dbus_message_new_method_error_literal (data->message,
+                                                       dbus_error_name,
+                                                       error->message);
       g_dbus_connection_send_message (data->connection, reply, NULL, NULL);
       g_free (dbus_error_name);
       g_error_free (error);
@@ -3003,7 +3003,10 @@ invoke_set_property_in_idle_cb (gpointer _data)
     {
       reply = g_dbus_message_new_method_error (data->message,
                                                "org.freedesktop.DBus.Error.InvalidArgs",
-                                               _("Type of property to set is incorrect"));
+                                               _("Error setting property `%s': Expected type `%s' but got `%s'"),
+                                               data->property_info->name,
+                                               data->property_info->signature,
+                                               g_variant_get_type_string (value));
       goto out;
     }
 
@@ -3019,9 +3022,9 @@ invoke_set_property_in_idle_cb (gpointer _data)
       gchar *dbus_error_name;
       g_assert (error != NULL);
       dbus_error_name = g_dbus_error_encode_gerror (error);
-      reply = g_dbus_message_new_method_error (data->message,
-                                               dbus_error_name,
-                                               error->message);
+      reply = g_dbus_message_new_method_error_literal (data->message,
+                                                       dbus_error_name,
+                                                       error->message);
       g_free (dbus_error_name);
       g_error_free (error);
     }
@@ -3092,7 +3095,8 @@ validate_and_maybe_schedule_property_getset (GDBusConnection            *connect
     {
       reply = g_dbus_message_new_method_error (message,
                                                "org.freedesktop.DBus.Error.InvalidArgs",
-                                               _("No such property"));
+                                               _("No such property `%s'"),
+                                               property_name);
       g_dbus_connection_send_message_unlocked (connection, reply, NULL, NULL);
       g_object_unref (reply);
       handled = TRUE;
@@ -3103,7 +3107,8 @@ validate_and_maybe_schedule_property_getset (GDBusConnection            *connect
     {
       reply = g_dbus_message_new_method_error (message,
                                                "org.freedesktop.DBus.Error.InvalidArgs",
-                                               _("Property is not readable"));
+                                               _("Property `%s' is not readable"),
+                                               property_name);
       g_dbus_connection_send_message_unlocked (connection, reply, NULL, NULL);
       g_object_unref (reply);
       handled = TRUE;
@@ -3113,7 +3118,8 @@ validate_and_maybe_schedule_property_getset (GDBusConnection            *connect
     {
       reply = g_dbus_message_new_method_error (message,
                                                "org.freedesktop.DBus.Error.InvalidArgs",
-                                               _("Property is not writable"));
+                                               _("Property `%s' is not writable"),
+                                               property_name);
       g_dbus_connection_send_message_unlocked (connection, reply, NULL, NULL);
       g_object_unref (reply);
       handled = TRUE;
@@ -3180,7 +3186,8 @@ handle_getset_property (GDBusConnection *connection,
       GDBusMessage *reply;
       reply = g_dbus_message_new_method_error (message,
                                                "org.freedesktop.DBus.Error.InvalidArgs",
-                                               _("No such interface"));
+                                               _("No such interface `%s'"),
+                                               interface_name);
       g_dbus_connection_send_message_unlocked (eo->connection, reply, NULL, NULL);
       g_object_unref (reply);
       handled = TRUE;
@@ -3349,7 +3356,8 @@ handle_get_all_properties (GDBusConnection *connection,
       GDBusMessage *reply;
       reply = g_dbus_message_new_method_error (message,
                                                "org.freedesktop.DBus.Error.InvalidArgs",
-                                               _("No such interface"));
+                                               _("No such interface"),
+                                               interface_name);
       g_dbus_connection_send_message_unlocked (eo->connection, reply, NULL, NULL);
       g_object_unref (reply);
       handled = TRUE;
@@ -3581,6 +3589,7 @@ validate_and_maybe_schedule_method_call (GDBusConnection            *connection,
   GVariant *parameters;
   GSource *idle_source;
   gboolean handled;
+  gchar *in_signature;
 
   handled = FALSE;
 
@@ -3594,7 +3603,8 @@ validate_and_maybe_schedule_method_call (GDBusConnection            *connection,
     {
       reply = g_dbus_message_new_method_error (message,
                                                "org.freedesktop.DBus.Error.UnknownMethod",
-                                               _("No such method"));
+                                               _("No such method `%s'"),
+                                               g_dbus_message_get_member (message));
       g_dbus_connection_send_message_unlocked (connection, reply, NULL, NULL);
       g_object_unref (reply);
       handled = TRUE;
@@ -3603,17 +3613,24 @@ validate_and_maybe_schedule_method_call (GDBusConnection            *connection,
 
   /* Check that the incoming args are of the right type - if they are not, return
    * the org.freedesktop.DBus.Error.InvalidArgs error to the caller
+   *
+   * TODO: might also be worth caching the combined signature.
    */
-  if (g_strcmp0 (g_dbus_message_get_signature (message), method_info->in_signature) != 0)
+  in_signature = _g_dbus_compute_complete_signature (method_info->in_args, FALSE);
+  if (g_strcmp0 (g_dbus_message_get_signature (message), in_signature) != 0)
     {
       reply = g_dbus_message_new_method_error (message,
                                                "org.freedesktop.DBus.Error.InvalidArgs",
-                                               _("Signature of message does not match what is expected"));
+                                               _("Signature of message, `%s', does not match expected signature `%s'"),
+                                               g_dbus_message_get_signature (message),
+                                               in_signature);
       g_dbus_connection_send_message_unlocked (connection, reply, NULL, NULL);
       g_object_unref (reply);
+      g_free (in_signature);
       handled = TRUE;
       goto out;
     }
+  g_free (in_signature);
 
   parameters = g_dbus_message_get_body (message);
   if (parameters == NULL)
@@ -4476,7 +4493,8 @@ handle_subtree_method_invocation (GDBusConnection  *connection,
           GDBusMessage *reply;
           reply = g_dbus_message_new_method_error (message,
                                                    "org.freedesktop.DBus.Error.InvalidArgs",
-                                                   _("No such interface"));
+                                                   _("No such interface `%s'"),
+                                                   interface_name);
           g_dbus_connection_send_message (es->connection, reply, NULL, NULL);
           g_object_unref (reply);
           handled = TRUE;
@@ -4577,8 +4595,11 @@ process_subtree_vtable_message_in_idle_cb (gpointer _data)
     {
       GDBusMessage *reply;
       reply = g_dbus_message_new_method_error (data->message,
-                                                 "org.freedesktop.DBus.Error.UnknownMethod",
-                                                 _("Method doesn't exist"));
+                                               "org.freedesktop.DBus.Error.UnknownMethod",
+                                               _("Method `%s' on interface `%s' with signature `%s' does not exist"),
+                                               g_dbus_message_get_member (data->message),
+                                               g_dbus_message_get_interface (data->message),
+                                               g_dbus_message_get_signature (data->message));
       g_dbus_connection_send_message (data->es->connection, reply, NULL, NULL);
       g_object_unref (reply);
     }
@@ -4794,13 +4815,11 @@ handle_generic_get_machine_id_unlocked (GDBusConnection  *connection,
                                 NULL,
                                 &error))
         {
-          gchar *s;
-          s = g_strdup_printf (_("Unable to load /var/lib/dbus/machine-id: %s"), error->message);
-          g_error_free (error);
           reply = g_dbus_message_new_method_error (message,
                                                    "org.freedesktop.DBus.Error.Failed",
-                                                   s);
-          g_free (s);
+                                                   _("Unable to load /var/lib/dbus/machine-id: %s"),
+                                                   error->message);
+          g_error_free (error);
         }
       else
         {
diff --git a/gdbus/gdbusintrospection.c b/gdbus/gdbusintrospection.c
index 3f39c8a..63b945e 100644
--- a/gdbus/gdbusintrospection.c
+++ b/gdbus/gdbusintrospection.c
@@ -298,9 +298,7 @@ g_dbus_method_info_unref (GDBusMethodInfo *info)
   if (g_atomic_int_dec_and_test (&info->ref_count))
     {
       g_free (info->name);
-      g_free (info->in_signature);
       free_null_terminated_array (info->in_args, (GDestroyNotify) g_dbus_arg_info_unref);
-      g_free (info->out_signature);
       free_null_terminated_array (info->out_args, (GDestroyNotify) g_dbus_arg_info_unref);
       free_null_terminated_array (info->annotations, (GDestroyNotify) g_dbus_annotation_info_unref);
       g_free (info);
@@ -323,7 +321,6 @@ g_dbus_signal_info_unref (GDBusSignalInfo *info)
   if (g_atomic_int_dec_and_test (&info->ref_count))
     {
       g_free (info->name);
-      g_free (info->signature);
       free_null_terminated_array (info->args, (GDestroyNotify) g_dbus_arg_info_unref);
       free_null_terminated_array (info->annotations, (GDestroyNotify) g_dbus_annotation_info_unref);
       g_free (info);
@@ -440,20 +437,6 @@ g_dbus_arg_info_set (ParseData            *data,
     info->annotations = annotations;
 }
 
-static gchar *
-compute_signature (GDBusArgInfo **args,
-                   guint          num_args)
-{
-  GString *s;
-  guint n;
-
-  s = g_string_new ("");
-  for (n = 0; n < num_args; n++)
-    g_string_append (s, args[n]->signature);
-
-  return g_string_free (s, FALSE);
-}
-
 static void
 g_dbus_method_info_set (ParseData            *data,
                         GDBusMethodInfo      *info,
@@ -474,16 +457,12 @@ g_dbus_method_info_set (ParseData            *data,
       //info->in_num_args = in_num_args;
       info->in_args = in_args;
     }
-  g_free (info->in_signature);
-  info->in_signature = compute_signature (in_args, in_num_args);
 
   if (out_num_args != 0)
     {
       //info->out_num_args = out_num_args;
       info->out_args = out_args;
     }
-  g_free (info->out_signature);
-  info->out_signature = compute_signature (out_args, out_num_args);
 
   if (annotations != NULL)
     info->annotations = annotations;
@@ -507,8 +486,6 @@ g_dbus_signal_info_set (ParseData            *data,
       //info->num_args = num_args;
       info->args = args;
     }
-  g_free (info->signature);
-  info->signature = compute_signature (args, num_args);
 
   if (annotations != NULL)
     {
diff --git a/gdbus/gdbusintrospection.h b/gdbus/gdbusintrospection.h
index 4c35b8a..afbb455 100644
--- a/gdbus/gdbusintrospection.h
+++ b/gdbus/gdbusintrospection.h
@@ -69,9 +69,7 @@ struct _GDBusArgInfo
  * GDBusMethodInfo:
  * @ref_count: The reference count or -1 if statically allocated.
  * @name: The name of the D-Bus method, e.g. @RequestName.
- * @in_signature: The combined D-Bus signature of all arguments passed to the method.
  * @in_args: A pointer to a %NULL-terminated array of pointers to #GDBusArgInfo structures or %NULL if there are no in arguments.
- * @out_signature: The combined D-Bus signature of all arguments the method returns.
  * @out_args: A pointer to a %NULL-terminated array of pointers to #GDBusArgInfo structures or %NULL if there are no out arguments.
  * @annotations: A pointer to a %NULL-terminated array of pointers to #GDBusAnnotationInfo structures or %NULL if there are no annotations.
  *
@@ -81,9 +79,7 @@ struct _GDBusMethodInfo
 {
   volatile gint         ref_count;
   gchar                *name;
-  gchar                *in_signature;
   GDBusArgInfo        **in_args;
-  gchar                *out_signature;
   GDBusArgInfo        **out_args;
   GDBusAnnotationInfo **annotations;
 };
@@ -92,7 +88,6 @@ struct _GDBusMethodInfo
  * GDBusSignalInfo:
  * @ref_count: The reference count or -1 if statically allocated.
  * @name: The name of the D-Bus signal, e.g. "NameOwnerChanged".
- * @signature: The combined D-Bus signature of all arguments of the signal.
  * @args: A pointer to a %NULL-terminated array of pointers to #GDBusArgInfo structures or %NULL if there are no arguments.
  * @annotations: A pointer to a %NULL-terminated array of pointers to #GDBusAnnotationInfo structures or %NULL if there are no annotations.
  *
@@ -102,7 +97,6 @@ struct _GDBusSignalInfo
 {
   volatile gint         ref_count;
   gchar                *name;
-  gchar                *signature;
   GDBusArgInfo        **args;
   GDBusAnnotationInfo **annotations;
 };
diff --git a/gdbus/gdbusmessage.c b/gdbus/gdbusmessage.c
index e1f19bb..b4332f5 100644
--- a/gdbus/gdbusmessage.c
+++ b/gdbus/gdbusmessage.c
@@ -225,6 +225,37 @@ g_dbus_message_new_method_reply (GDBusMessage *method_call_message)
  * @method_call_message: A message of type %G_DBUS_MESSAGE_TYPE_METHOD_CALL to
  * create a reply message to.
  * @error_name: A valid D-Bus error name.
+ * @error_message_format: The D-Bus error message in a printf() format.
+ * @...: Arguments for @error_message_format.
+ *
+ * Creates a new #GDBusMessage that is an error reply to @method_call_message.
+ *
+ * Returns: A #GDBusMessage. Free with g_object_unref().
+ */
+GDBusMessage *
+g_dbus_message_new_method_error (GDBusMessage             *method_call_message,
+                                 const gchar              *error_name,
+                                 const gchar              *error_message_format,
+                                 ...)
+{
+  GDBusMessage *ret;
+  va_list var_args;
+
+  va_start (var_args, error_message_format);
+  ret = g_dbus_message_new_method_error_valist (method_call_message,
+                                                error_name,
+                                                error_message_format,
+                                                var_args);
+  va_end (var_args);
+
+  return ret;
+}
+
+/**
+ * g_dbus_message_new_method_error_literal:
+ * @method_call_message: A message of type %G_DBUS_MESSAGE_TYPE_METHOD_CALL to
+ * create a reply message to.
+ * @error_name: A valid D-Bus error name.
  * @error_message: The D-Bus error message.
  *
  * Creates a new #GDBusMessage that is an error reply to @method_call_message.
@@ -232,9 +263,9 @@ g_dbus_message_new_method_reply (GDBusMessage *method_call_message)
  * Returns: A #GDBusMessage. Free with g_object_unref().
  */
 GDBusMessage *
-g_dbus_message_new_method_error (GDBusMessage  *method_call_message,
-                                 const gchar   *error_name,
-                                 const gchar   *error_message)
+g_dbus_message_new_method_error_literal (GDBusMessage  *method_call_message,
+                                         const gchar   *error_name,
+                                         const gchar   *error_message)
 {
   GDBusMessage *message;
   const gchar *sender;
@@ -260,6 +291,34 @@ g_dbus_message_new_method_error (GDBusMessage  *method_call_message,
   return message;
 }
 
+/**
+ * g_dbus_message_new_method_error_valist:
+ * @method_call_message: A message of type %G_DBUS_MESSAGE_TYPE_METHOD_CALL to
+ * create a reply message to.
+ * @error_name: A valid D-Bus error name.
+ * @error_message_format: The D-Bus error message in a printf() format.
+ * @var_args: Arguments for @error_message_format.
+ *
+ * Like g_dbus_message_new_method_error() but intended for language bindings.
+ *
+ * Returns: A #GDBusMessage. Free with g_object_unref().
+ */
+GDBusMessage *
+g_dbus_message_new_method_error_valist (GDBusMessage             *method_call_message,
+                                        const gchar              *error_name,
+                                        const gchar              *error_message_format,
+                                        va_list                   var_args)
+{
+  GDBusMessage *ret;
+  gchar *error_message;
+  error_message = g_strdup_vprintf (error_message_format, var_args);
+  ret = g_dbus_message_new_method_error_literal (method_call_message,
+                                                 error_name,
+                                                 error_message);
+  g_free (error_message);
+  return ret;
+}
+
 /* ---------------------------------------------------------------------------------------------------- */
 
 /* TODO: need GI annotations to specify that any guchar value goes for the type */
diff --git a/gdbus/gdbusmessage.h b/gdbus/gdbusmessage.h
index 224f66f..06d72e6 100644
--- a/gdbus/gdbusmessage.h
+++ b/gdbus/gdbusmessage.h
@@ -81,7 +81,15 @@ GDBusMessage             *g_dbus_message_new_method_call    (const gchar
 GDBusMessage             *g_dbus_message_new_method_reply   (GDBusMessage             *method_call_message);
 GDBusMessage             *g_dbus_message_new_method_error   (GDBusMessage             *method_call_message,
                                                              const gchar              *error_name,
-                                                             const gchar              *error_message);
+                                                             const gchar              *error_message_format,
+                                                             ...);
+GDBusMessage             *g_dbus_message_new_method_error_valist (GDBusMessage             *method_call_message,
+                                                                  const gchar              *error_name,
+                                                                  const gchar              *error_message_format,
+                                                                  va_list                   var_args);
+GDBusMessage             *g_dbus_message_new_method_error_literal (GDBusMessage             *method_call_message,
+                                                                   const gchar              *error_name,
+                                                                   const gchar              *error_message);
 gchar                    *g_dbus_message_print              (GDBusMessage             *message,
                                                              guint                     indent);
 
diff --git a/gdbus/gdbusmethodinvocation.c b/gdbus/gdbusmethodinvocation.c
index 0bd096d..dc6950b 100644
--- a/gdbus/gdbusmethodinvocation.c
+++ b/gdbus/gdbusmethodinvocation.c
@@ -595,33 +595,23 @@ g_dbus_method_invocation_return_value (GDBusMethodInvocation *invocation,
   /* if we have introspection data, check that the signature of @parameters is correct */
   if (invocation->priv->method_info != NULL)
     {
-      gboolean pass;
+      gchar *signature;
+      const gchar *type_string;
 
-      pass = FALSE;
-      if (parameters == NULL)
-        {
-          if (g_strcmp0 (invocation->priv->method_info->out_signature, "") == 0)
-            pass = TRUE;
-        }
-      else
-        {
-          const gchar *type_string;
-          gchar *sig_with_paren;
-
-          /* this can probably be done a lot more efficiently */
-          sig_with_paren = g_strdup_printf ("(%s)", invocation->priv->method_info->out_signature);
-          type_string = g_variant_get_type_string (parameters);
-          if (g_strcmp0 (sig_with_paren, type_string) == 0)
-            pass = TRUE;
-          g_free (sig_with_paren);
-        }
+      type_string = "()";
+      if (parameters != NULL)
+        type_string = g_variant_get_type_string (parameters);
+      signature = _g_dbus_compute_complete_signature (invocation->priv->method_info->out_args, TRUE);
 
-      if (!pass)
+      if (g_strcmp0 (type_string, signature) != 0)
         {
-          g_warning (_("Type of return value is incorrect, expected type `(%s)'"),
-                     invocation->priv->method_info->out_signature);
+          g_warning (_("Type of return value is incorrect, got `%s', expected  `%s'"),
+                     type_string,
+                     signature);
+          g_free (signature);
           goto out;
         }
+      g_free (signature);
     }
 
   reply = g_dbus_message_new_method_reply (invocation->priv->message);
@@ -795,9 +785,9 @@ g_dbus_method_invocation_return_dbus_error (GDBusMethodInvocation *invocation,
   g_return_if_fail (error_name != NULL && g_dbus_is_name (error_name));
   g_return_if_fail (error_message != NULL);
 
-  reply = g_dbus_message_new_method_error (invocation->priv->message,
-                                           error_name,
-                                           error_message);
+  reply = g_dbus_message_new_method_error_literal (invocation->priv->message,
+                                                   error_name,
+                                                   error_message);
   g_dbus_connection_send_message (g_dbus_method_invocation_get_connection (invocation), reply, NULL, NULL);
   g_object_unref (reply);
 
diff --git a/gdbus/gdbusprivate.c b/gdbus/gdbusprivate.c
index 3ef661b..08295d4 100644
--- a/gdbus/gdbusprivate.c
+++ b/gdbus/gdbusprivate.c
@@ -38,6 +38,7 @@
 #include "gdbusprivate.h"
 #include "gdbusmessage.h"
 #include "gdbuserror.h"
+#include "gdbusintrospection.h"
 
 /* ---------------------------------------------------------------------------------------------------- */
 
@@ -1014,3 +1015,26 @@ _g_dbus_initialize (void)
       g_once_init_leave (&initialized, 1);
     }
 }
+
+/* ---------------------------------------------------------------------------------------------------- */
+
+gchar *
+_g_dbus_compute_complete_signature (GDBusArgInfo **args,
+                                    gboolean       include_parentheses)
+{
+  GString *s;
+  guint n;
+
+  if (include_parentheses)
+    s = g_string_new ("(");
+  else
+    s = g_string_new ("");
+  if (args != NULL)
+    for (n = 0; args[n] != NULL; n++)
+      g_string_append (s, args[n]->signature);
+
+  if (include_parentheses)
+    g_string_append_c (s, ')');
+
+  return g_string_free (s, FALSE);
+}
diff --git a/gdbus/gdbusprivate.h b/gdbus/gdbusprivate.h
index 8d59c1a..c01059d 100644
--- a/gdbus/gdbusprivate.h
+++ b/gdbus/gdbusprivate.h
@@ -73,6 +73,9 @@ gboolean _g_dbus_address_parse_entry (const gchar  *address_entry,
                                       GHashTable  **out_key_value_pairs,
                                       GError      **error);
 
+gchar * _g_dbus_compute_complete_signature (GDBusArgInfo **args,
+                                            gboolean       include_parentheses);
+
 /* ---------------------------------------------------------------------------------------------------- */
 
 G_END_DECLS
diff --git a/gdbus/gdbusproxy.c b/gdbus/gdbusproxy.c
index 58e77bf..651fa83 100644
--- a/gdbus/gdbusproxy.c
+++ b/gdbus/gdbusproxy.c
@@ -1277,28 +1277,37 @@ validate_method_return (const char             *method_name,
                         const GDBusMethodInfo  *expected_method_info,
                         GError                **error)
 {
-  const char *type_string;
-  if (value == NULL || !expected_method_info)
-    return TRUE;
+  const gchar *type_string;
+  gchar *signature;
+  gboolean ret;
+
+  ret = TRUE;
+  signature = NULL;
+
+  if (value == NULL || expected_method_info == NULL)
+    goto out;
 
   /* Shouldn't happen... */
   if (g_variant_classify (value) != G_VARIANT_CLASS_TUPLE)
-    return TRUE;
+    goto out;
 
   type_string = g_variant_get_type_string (value);
-  /* introspection data doesn't have the () characters... */
-  if (strncmp (type_string + 1, expected_method_info->out_signature, strlen (type_string + 1) - 1) != 0)
+  signature = _g_dbus_compute_complete_signature (expected_method_info->out_args, TRUE);
+  if (g_strcmp0 (type_string, signature) != 0)
     {
       g_set_error (error,
                    G_IO_ERROR,
                    G_IO_ERROR_INVALID_ARGUMENT,
-                   _("Method %s returned signature %s, but expected (%s)"),
+                   _("Method `%s' returned signature `%s', but expected `%s'"),
                    method_name,
                    type_string,
-                   expected_method_info->out_signature);
-      return FALSE;
+                   signature);
+      ret = FALSE;
     }
-  return TRUE;
+
+ out:
+  g_free (signature);
+  return ret;
 }
 
 /**
diff --git a/gdbus/tests/export.c b/gdbus/tests/export.c
index d98a57e..2b5abb2 100644
--- a/gdbus/tests/export.c
+++ b/gdbus/tests/export.c
@@ -57,16 +57,16 @@ static const GDBusMethodInfo foo_method_info_method1 =
 {
   -1,
   "Method1",
-  "s", (GDBusArgInfo **) &foo_method1_in_arg_pointers,
-  "s", (GDBusArgInfo **) &foo_method1_out_arg_pointers,
+  (GDBusArgInfo **) &foo_method1_in_arg_pointers,
+  (GDBusArgInfo **) &foo_method1_out_arg_pointers,
   NULL
 };
 static const GDBusMethodInfo foo_method_info_method2 =
 {
   -1,
   "Method2",
-  "", NULL,
-  "", NULL,
+  NULL,
+  NULL,
   NULL
 };
 static const GDBusMethodInfo *foo_method_info_pointers[] = {&foo_method_info_method1, &foo_method_info_method2, NULL};
@@ -75,7 +75,7 @@ static const GDBusSignalInfo foo_signal_info =
 {
   -1,
   "SignalAlpha",
-  "", NULL,
+  NULL,
   NULL
 };
 static const GDBusSignalInfo *foo_signal_info_pointers[] = {&foo_signal_info, NULL};
@@ -201,15 +201,15 @@ static const GDBusMethodInfo bar_method_info[] =
   {
     -1,
     "MethodA",
-    "", NULL,
-    "", NULL,
+    NULL,
+    NULL,
     NULL
   },
   {
     -1,
     "MethodB",
-    "", NULL,
-    "", NULL,
+    NULL,
+    NULL,
     NULL
   }
 };
@@ -220,7 +220,7 @@ static const GDBusSignalInfo bar_signal_info[] =
   {
     -1,
     "SignalMars",
-    "", NULL,
+    NULL,
     NULL
   }
 };
@@ -255,8 +255,8 @@ static const GDBusMethodInfo dyna_method_info[] =
   {
     -1,
     "DynaCyber",
-    "", NULL,
-    "", NULL,
+    NULL,
+    NULL,
     NULL
   }
 };
@@ -809,7 +809,7 @@ test_dispatch_thread_func (gpointer user_data)
                                            NULL,
                                            &error);
   g_assert_error (error, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS);
-  g_assert_cmpstr (error->message, ==, "GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs: Signature of message does not match what is expected");
+  g_assert_cmpstr (error->message, ==, "GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs: Signature of message, `s', does not match expected signature `'");
   g_error_free (error);
   g_assert (value == NULL);
 
@@ -822,7 +822,7 @@ test_dispatch_thread_func (gpointer user_data)
                                            NULL,
                                            &error);
   g_assert_error (error, G_DBUS_ERROR, G_DBUS_ERROR_UNKNOWN_METHOD);
-  g_assert_cmpstr (error->message, ==, "GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such method");
+  g_assert_cmpstr (error->message, ==, "GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such method `NonExistantMethod'");
   g_error_free (error);
   g_assert (value == NULL);
 
@@ -857,7 +857,7 @@ test_dispatch_thread_func (gpointer user_data)
                                            &error);
   g_assert (value == NULL);
   g_assert_error (error, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS);
-  g_assert_cmpstr (error->message, ==, "GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs: No such property");
+  g_assert_cmpstr (error->message, ==, "GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs: No such property `ThisDoesntExist'");
   g_error_free (error);
 
   error = NULL;
@@ -872,7 +872,7 @@ test_dispatch_thread_func (gpointer user_data)
                                            &error);
   g_assert (value == NULL);
   g_assert_error (error, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS);
-  g_assert_cmpstr (error->message, ==, "GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs: Property is not readable");
+  g_assert_cmpstr (error->message, ==, "GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs: Property `NotReadable' is not readable");
   g_error_free (error);
 
   error = NULL;
@@ -904,7 +904,7 @@ test_dispatch_thread_func (gpointer user_data)
                                            &error);
   g_assert (value == NULL);
   g_assert_error (error, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS);
-  g_assert_cmpstr (error->message, ==, "GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs: Property is not writable");
+  g_assert_cmpstr (error->message, ==, "GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs: Property `NotWritable' is not writable");
   g_error_free (error);
 
   error = NULL;
diff --git a/gdbus/tests/introspection.c b/gdbus/tests/introspection.c
index 77bd566..5fe84ed 100644
--- a/gdbus/tests/introspection.c
+++ b/gdbus/tests/introspection.c
@@ -79,9 +79,7 @@ introspection_on_proxy_appeared (GDBusConnection *connection,
   g_assert (method_info == NULL);
   method_info = g_dbus_interface_info_lookup_method (interface_info, "Introspect");
   g_assert (method_info != NULL);
-  g_assert_cmpstr (method_info->in_signature, ==, "");
   g_assert (method_info->in_args == NULL);
-  g_assert_cmpstr (method_info->out_signature, ==, "s");
   g_assert (method_info->out_args != NULL);
   g_assert (method_info->out_args[0] != NULL);
   g_assert (method_info->out_args[1] == NULL);
@@ -91,7 +89,14 @@ introspection_on_proxy_appeared (GDBusConnection *connection,
   g_assert (interface_info != NULL);
   signal_info = g_dbus_interface_info_lookup_signal (interface_info, "TestSignal");
   g_assert (signal_info != NULL);
-  g_assert_cmpstr (signal_info->signature, ==, "sov");
+  g_assert (signal_info->args != NULL);
+  g_assert (signal_info->args[0] != NULL);
+  g_assert_cmpstr (signal_info->args[0]->signature, ==, "s");
+  g_assert (signal_info->args[1] != NULL);
+  g_assert_cmpstr (signal_info->args[1]->signature, ==, "o");
+  g_assert (signal_info->args[2] != NULL);
+  g_assert_cmpstr (signal_info->args[2]->signature, ==, "v");
+  g_assert (signal_info->args[3] == NULL);
 
   g_dbus_node_info_unref (node_info);
   g_variant_unref (result);