GDBusMessage: Make it possible to lock and copy messages

Don't actually use this yet as that will require a couple of
modifications to the filter function signature. This is part of the
bug-fix for

 https://bugzilla.gnome.org/show_bug.cgi?id=624546#c8

Signed-off-by: David Zeuthen <davidz@redhat.com>

docs/reference/gio/gio-sections.txt

@@ -2334,6 +2334,9 @@ 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_locked
+g_dbus_message_lock
+g_dbus_message_copy
 g_dbus_message_get_byte_order
 g_dbus_message_set_byte_order
 g_dbus_message_get_message_type

gio/gdbusmessage.c

@@ -92,6 +92,8 @@ struct _GDBusMessage
 
   GDBusMessageType type;
   GDBusMessageFlags flags;
+  gboolean locked;
+  GDBusMessageByteOrder byte_order;
   guchar major_protocol_version;
   guint32 serial;
   GHashTable *headers;
@@ -99,7 +101,12 @@ struct _GDBusMessage
 #ifdef G_OS_UNIX
   GUnixFDList *fd_list;
 #endif
-  GDBusMessageByteOrder byte_order;
+};
+
+enum
+{
+  PROP_0,
+  PROP_LOCKED
 };
 
 G_DEFINE_TYPE (GDBusMessage, g_dbus_message, G_TYPE_OBJECT);
@@ -122,14 +129,52 @@ g_dbus_message_finalize (GObject *object)
     G_OBJECT_CLASS (g_dbus_message_parent_class)->finalize (object);
 }
 
+static void
+g_dbus_message_get_property (GObject    *object,
+                             guint       prop_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GDBusMessage *message = G_DBUS_MESSAGE (object);
+
+  switch (prop_id)
+    {
+    case PROP_LOCKED:
+      g_value_set_boolean (value, g_dbus_message_get_locked (message));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
 static void
 g_dbus_message_class_init (GDBusMessageClass *klass)
 {
   GObjectClass *gobject_class;
 
   gobject_class = G_OBJECT_CLASS (klass);
-
   gobject_class->finalize     = g_dbus_message_finalize;
+  gobject_class->get_property = g_dbus_message_get_property;
+
+  /**
+   * GDBusConnection:locked:
+   *
+   * A boolean specifying whether the message is locked.
+   *
+   * Since: 2.26
+   */
+  g_object_class_install_property (gobject_class,
+                                   PROP_LOCKED,
+                                   g_param_spec_boolean ("locked",
+                                                         P_("Locked"),
+                                                         P_("Whether the message is locked"),
+                                                         FALSE,
+                                                         G_PARAM_READABLE |
+                                                         G_PARAM_STATIC_NAME |
+                                                         G_PARAM_STATIC_BLURB |
+                                                         G_PARAM_STATIC_NICK));
 }
 
 static void
@@ -413,6 +458,13 @@ g_dbus_message_set_byte_order (GDBusMessage          *message,
                                GDBusMessageByteOrder  byte_order)
 {
   g_return_if_fail (G_IS_DBUS_MESSAGE (message));
+
+  if (message->locked)
+    {
+      g_warning ("%s: Attempted to modify a locked message", G_STRFUNC);
+      return;
+    }
+
   message->byte_order = byte_order;
 }
 
@@ -452,6 +504,13 @@ g_dbus_message_set_message_type (GDBusMessage      *message,
 {
   g_return_if_fail (G_IS_DBUS_MESSAGE (message));
   g_return_if_fail (type >=0 && type < 256);
+
+  if (message->locked)
+    {
+      g_warning ("%s: Attempted to modify a locked message", G_STRFUNC);
+      return;
+    }
+
   message->type = type;
 }
 
@@ -492,6 +551,13 @@ g_dbus_message_set_flags (GDBusMessage       *message,
 {
   g_return_if_fail (G_IS_DBUS_MESSAGE (message));
   g_return_if_fail (flags >=0 && flags < 256);
+
+  if (message->locked)
+    {
+      g_warning ("%s: Attempted to modify a locked message", G_STRFUNC);
+      return;
+    }
+
   message->flags = flags;
 }
 
@@ -528,6 +594,13 @@ g_dbus_message_set_serial (GDBusMessage  *message,
                            guint32        serial)
 {
   g_return_if_fail (G_IS_DBUS_MESSAGE (message));
+
+  if (message->locked)
+    {
+      g_warning ("%s: Attempted to modify a locked message", G_STRFUNC);
+      return;
+    }
+
   message->serial = serial;
 }
 
@@ -575,6 +648,13 @@ g_dbus_message_set_header (GDBusMessage             *message,
 {
   g_return_if_fail (G_IS_DBUS_MESSAGE (message));
   g_return_if_fail (header_field >=0 && header_field < 256);
+
+  if (message->locked)
+    {
+      g_warning ("%s: Attempted to modify a locked message", G_STRFUNC);
+      return;
+    }
+
   if (value == NULL)
     {
       g_hash_table_remove (message->headers, GUINT_TO_POINTER (header_field));
@@ -659,6 +739,12 @@ g_dbus_message_set_body (GDBusMessage  *message,
   g_return_if_fail (G_IS_DBUS_MESSAGE (message));
   g_return_if_fail ((body == NULL) || g_variant_is_of_type (body, G_VARIANT_TYPE_TUPLE));
 
+  if (message->locked)
+    {
+      g_warning ("%s: Attempted to modify a locked message", G_STRFUNC);
+      return;
+    }
+
   if (message->body != NULL)
     g_variant_unref (message->body);
   if (body == NULL)
@@ -726,6 +812,13 @@ g_dbus_message_set_unix_fd_list (GDBusMessage  *message,
 {
   g_return_if_fail (G_IS_DBUS_MESSAGE (message));
   g_return_if_fail (fd_list == NULL || G_IS_UNIX_FD_LIST (fd_list));
+
+  if (message->locked)
+    {
+      g_warning ("%s: Attempted to modify a locked message", G_STRFUNC);
+      return;
+    }
+
   if (message->fd_list != NULL)
     g_object_unref (message->fd_list);
   if (fd_list != NULL)
@@ -3047,3 +3140,116 @@ g_dbus_message_print (GDBusMessage *message,
 
   return g_string_free (str, FALSE);
 }
+
+/**
+ * g_dbus_message_get_locked:
+ * @message: A #GDBusMessage.
+ *
+ * Checks whether @message is locked. To monitor changes to this
+ * value, conncet to the #GObject::notify signal to listen for changes
+ * on the #GDBusMessage:locked property.
+ *
+ * Returns: %TRUE if @message is locked, %FALSE otherwise.
+ *
+ * Since: 2.26
+ */
+gboolean
+g_dbus_message_get_locked (GDBusMessage *message)
+{
+  g_return_val_if_fail (G_IS_DBUS_MESSAGE (message), FALSE);
+  return message->locked;
+}
+
+/**
+ * g_dbus_message_lock:
+ * @message: A #GDBusMessage.
+ *
+ * If @message is locked, does nothing. Otherwise locks the message.
+ *
+ * Since: 2.26
+ */
+void
+g_dbus_message_lock (GDBusMessage *message)
+{
+  g_return_if_fail (G_IS_DBUS_MESSAGE (message));
+
+  if (message->locked)
+    goto out;
+
+  message->locked = TRUE;
+  g_object_notify (G_OBJECT (message), "locked");
+
+ out:
+  ;
+}
+
+/**
+ * g_dbus_message_copy:
+ * @message: A #GDBusMessage.
+ * @error: Return location for error or %NULL.
+ *
+ * Copies @message. The copy is a deep copy and the returned
+ * #GDBusMessage is completely identical except that it is guaranteed
+ * to not be locked and the serial will be set to 0.
+ *
+ * This operation can fail if e.g. @message contains file descriptors
+ * and the per-process or system-wide open files limit is reached.
+ *
+ * Returns: A new #GDBusMessage or %NULL if @error is set. Free with
+ * g_object_unref().
+ *
+ * Since: 2.26
+ */
+GDBusMessage *
+g_dbus_message_copy (GDBusMessage  *message,
+                     GError       **error)
+{
+  GDBusMessage *ret;
+  GHashTableIter iter;
+  gpointer header_key;
+  GVariant *header_value;
+
+  g_return_val_if_fail (G_IS_DBUS_MESSAGE (message), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  ret = g_dbus_message_new ();
+  ret->type                   = message->type;
+  ret->flags                  = message->flags;
+  ret->byte_order             = message->byte_order;
+  ret->major_protocol_version = message->major_protocol_version;
+
+#ifdef G_OS_UNIX
+  if (message->fd_list != NULL)
+    {
+      gint n;
+      gint num_fds;
+      const gint *fds;
+
+      ret->fd_list = g_unix_fd_list_new ();
+      fds = g_unix_fd_list_peek_fds (message->fd_list, &num_fds);
+      for (n = 0; n < num_fds; n++)
+        {
+          if (g_unix_fd_list_append (ret->fd_list,
+                                     fds[n],
+                                     error) == -1)
+            {
+              g_object_unref (ret);
+              ret = NULL;
+              goto out;
+            }
+        }
+    }
+#endif
+
+  /* see https://bugzilla.gnome.org/show_bug.cgi?id=624546#c8 for why it's fine
+   * to just ref (as opposed to deep-copying) the GVariant instances
+   */
+  ret->body = message->body != NULL ? g_variant_ref (message->body) : NULL;
+  g_hash_table_iter_init (&iter, message->headers);
+  while (g_hash_table_iter_next (&iter, &header_key, (gpointer) &header_value))
+    g_hash_table_insert (ret->headers, header_key, g_variant_ref (header_value));
+
+ out:
+  return ret;
+}
+

gio/gdbusmessage.h

@@ -58,7 +58,10 @@ GDBusMessage             *g_dbus_message_new_method_error_literal (GDBusMessage
                                                                    const gchar              *error_message);
 gchar                    *g_dbus_message_print              (GDBusMessage             *message,
                                                              guint                     indent);
-
+gboolean                  g_dbus_message_get_locked         (GDBusMessage             *message);
+void                      g_dbus_message_lock               (GDBusMessage             *message);
+GDBusMessage             *g_dbus_message_copy               (GDBusMessage             *message,
+                                                             GError                  **error);
 GDBusMessageByteOrder     g_dbus_message_get_byte_order     (GDBusMessage             *message);
 void                      g_dbus_message_set_byte_order     (GDBusMessage             *message,
                                                              GDBusMessageByteOrder     byte_order);

gio/gio.symbols

@@ -1703,6 +1703,9 @@ g_dbus_message_new_method_error_valist
 g_dbus_message_new_method_reply
 g_dbus_message_new_signal
 g_dbus_message_bytes_needed
+g_dbus_message_get_locked
+g_dbus_message_lock
+g_dbus_message_copy
 g_dbus_message_get_arg0
 g_dbus_message_get_body
 g_dbus_message_get_byte_order

gio/tests/Makefile.am

@@ -41,6 +41,7 @@ TEST_PROGS +=	 		\
 	async-close-output-stream \
 	gdbus-addresses		\
 	network-address		\
+	gdbus-message		\
 	$(NULL)
 
 if OS_UNIX
@@ -219,6 +220,9 @@ gdbus_addresses_LDADD = $(progs_ldadd)
 gdbus_connection_SOURCES = gdbus-connection.c gdbus-sessionbus.c gdbus-sessionbus.h gdbus-tests.h gdbus-tests.c
 gdbus_connection_LDADD = $(progs_ldadd)
 
+gdbus_message_SOURCES = gdbus-message.c
+gdbus_message_LDADD = $(progs_ldadd)
+
 gdbus_names_SOURCES = gdbus-names.c gdbus-sessionbus.c gdbus-sessionbus.h gdbus-tests.h gdbus-tests.c
 gdbus_names_LDADD = $(progs_ldadd)
 

gio/tests/gdbus-message.c

@@ -0,0 +1,153 @@
+/* GLib testing framework examples and tests
+ *
+ * Copyright (C) 2008-2010 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: David Zeuthen <davidz@redhat.com>
+ */
+
+#include <locale.h>
+#include <gio/gio.h>
+
+/* ---------------------------------------------------------------------------------------------------- */
+
+static void
+on_notify_locked (GObject    *object,
+                  GParamSpec *pspec,
+                  gpointer    user_data)
+{
+  gint *count = user_data;
+  *count += 1;
+}
+
+static void
+message_lock (void)
+{
+  GDBusMessage *m;
+  gint count;
+
+  count = 0;
+  m = g_dbus_message_new ();
+  g_signal_connect (m,
+                    "notify::locked",
+                    G_CALLBACK (on_notify_locked),
+                    &count);
+  g_assert (!g_dbus_message_get_locked (m));
+  g_dbus_message_lock (m);
+  g_assert (g_dbus_message_get_locked (m));
+  g_assert_cmpint (count, ==, 1);
+  g_dbus_message_lock (m);
+  g_assert (g_dbus_message_get_locked (m));
+  g_assert_cmpint (count, ==, 1);
+
+  if (g_test_trap_fork (0, G_TEST_TRAP_SILENCE_STDERR))
+    g_dbus_message_set_serial (m, 42);
+  g_test_trap_assert_failed (); g_test_trap_assert_stderr ("*Attempted to modify a locked message*");
+
+  if (g_test_trap_fork (0, G_TEST_TRAP_SILENCE_STDERR))
+    g_dbus_message_set_byte_order (m, G_DBUS_MESSAGE_BYTE_ORDER_BIG_ENDIAN);
+  g_test_trap_assert_failed (); g_test_trap_assert_stderr ("*Attempted to modify a locked message*");
+
+  if (g_test_trap_fork (0, G_TEST_TRAP_SILENCE_STDERR))
+    g_dbus_message_set_message_type (m, G_DBUS_MESSAGE_TYPE_METHOD_CALL);
+  g_test_trap_assert_failed (); g_test_trap_assert_stderr ("*Attempted to modify a locked message*");
+
+  if (g_test_trap_fork (0, G_TEST_TRAP_SILENCE_STDERR))
+    g_dbus_message_set_flags (m, G_DBUS_MESSAGE_FLAGS_NONE);
+  g_test_trap_assert_failed (); g_test_trap_assert_stderr ("*Attempted to modify a locked message*");
+
+  if (g_test_trap_fork (0, G_TEST_TRAP_SILENCE_STDERR))
+    g_dbus_message_set_body (m, NULL);
+  g_test_trap_assert_failed (); g_test_trap_assert_stderr ("*Attempted to modify a locked message*");
+
+  if (g_test_trap_fork (0, G_TEST_TRAP_SILENCE_STDERR))
+    g_dbus_message_set_header (m, 0, NULL);
+  g_test_trap_assert_failed (); g_test_trap_assert_stderr ("*Attempted to modify a locked message*");
+
+  g_object_unref (m);
+}
+
+/* ---------------------------------------------------------------------------------------------------- */
+
+static void
+message_copy (void)
+{
+  GDBusMessage *m;
+  GDBusMessage *copy;
+  GError *error;
+  guchar *m_headers;
+  guchar *copy_headers;
+  guint n;
+
+  m = g_dbus_message_new_method_call ("org.example.Name",
+                                      "/org/example/Object",
+                                      "org.example.Interface",
+                                      "Method");
+  g_dbus_message_set_serial (m, 42);
+  g_dbus_message_set_byte_order (m, G_DBUS_MESSAGE_BYTE_ORDER_BIG_ENDIAN);
+
+  error = NULL;
+  copy = g_dbus_message_copy (m, &error);
+  g_assert_no_error (error);
+  g_assert (G_IS_DBUS_MESSAGE (copy));
+  g_assert (m != copy);
+  g_assert_cmpint (G_OBJECT (m)->ref_count, ==, 1);
+  g_assert_cmpint (G_OBJECT (copy)->ref_count, ==, 1);
+
+  g_assert_cmpint (g_dbus_message_get_serial (copy), ==, 0);
+  g_assert_cmpint (g_dbus_message_get_byte_order (copy), ==, g_dbus_message_get_byte_order (m));
+  g_assert_cmpint (g_dbus_message_get_flags (copy), ==, g_dbus_message_get_flags (m));
+  g_assert_cmpint (g_dbus_message_get_message_type (copy), ==, g_dbus_message_get_message_type (m));
+  m_headers = g_dbus_message_get_header_fields (m);
+  copy_headers = g_dbus_message_get_header_fields (copy);
+  g_assert (m_headers != NULL);
+  g_assert (copy_headers != NULL);
+  for (n = 0; m_headers[n] != 0; n++)
+    {
+      GVariant *m_val;
+      GVariant *copy_val;
+      m_val = g_dbus_message_get_header (m, m_headers[n]);
+      copy_val = g_dbus_message_get_header (m, m_headers[n]);
+      g_assert (m_val != NULL);
+      g_assert (copy_val != NULL);
+      g_assert (g_variant_equal (m_val, copy_val));
+    }
+  g_assert_cmpint (n, >, 0); /* make sure we actually compared headers etc. */
+  g_assert_cmpint (copy_headers[n], ==, 0);
+  g_free (m_headers);
+  g_free (copy_headers);
+
+  g_object_unref (copy);
+  g_object_unref (m);
+}
+
+/* ---------------------------------------------------------------------------------------------------- */
+
+int
+main (int   argc,
+      char *argv[])
+{
+  setlocale (LC_ALL, "C");
+
+  g_type_init ();
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/gdbus/message/lock", message_lock);
+  g_test_add_func ("/gdbus/message/copy", message_copy);
+  return g_test_run();
+}
+