gio/gdbusconnection.h

   1 /* GDBus - GLib D-Bus Library
   2  *
   3  * Copyright (C) 2008-2010 Red Hat, Inc.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General
  16  * Public License along with this library; if not, write to the
  17  * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  18  * Boston, MA 02111-1307, USA.
  19  *
  20  * Author: David Zeuthen <davidz@redhat.com>
  21  */
  22
  23 #if !defined (__GIO_GIO_H_INSIDE__) && !defined (GIO_COMPILATION)
  24 #error "Only <gio/gio.h> can be included directly."
  25 #endif
  26
  27 #ifndef __G_DBUS_CONNECTION_H__
  28 #define __G_DBUS_CONNECTION_H__
  29
  30 #include <gio/giotypes.h>
  31
  32 G_BEGIN_DECLS
  33
  34 #define G_TYPE_DBUS_CONNECTION         (g_dbus_connection_get_type ())
  35 #define G_DBUS_CONNECTION(o)           (G_TYPE_CHECK_INSTANCE_CAST ((o), G_TYPE_DBUS_CONNECTION, GDBusConnection))
  36 #define G_IS_DBUS_CONNECTION(o)        (G_TYPE_CHECK_INSTANCE_TYPE ((o), G_TYPE_DBUS_CONNECTION))
  37
  38 GType            g_dbus_connection_get_type                   (void) G_GNUC_CONST;
  39
  40 /* ---------------------------------------------------------------------------------------------------- */
  41
  42 void              g_bus_get                    (GBusType             bus_type,
  43                                                 GCancellable        *cancellable,
  44                                                 GAsyncReadyCallback  callback,
  45                                                 gpointer             user_data);
  46 GDBusConnection  *g_bus_get_finish             (GAsyncResult        *res,
  47                                                 GError             **error);
  48 GDBusConnection  *g_bus_get_sync               (GBusType            bus_type,
  49                                                 GCancellable       *cancellable,
  50                                                 GError            **error);
  51
  52 /* ---------------------------------------------------------------------------------------------------- */
  53
  54 void             g_dbus_connection_new                        (GIOStream              *stream,
  55                                                                const gchar            *guid,
  56                                                                GDBusConnectionFlags    flags,
  57                                                                GDBusAuthObserver      *observer,
  58                                                                GCancellable           *cancellable,
  59                                                                GAsyncReadyCallback     callback,
  60                                                                gpointer                user_data);
  61 GDBusConnection *g_dbus_connection_new_finish                 (GAsyncResult           *res,
  62                                                                GError                **error);
  63 GDBusConnection *g_dbus_connection_new_sync                   (GIOStream              *stream,
  64                                                                const gchar            *guid,
  65                                                                GDBusConnectionFlags    flags,
  66                                                                GDBusAuthObserver      *observer,
  67                                                                GCancellable           *cancellable,
  68                                                                GError                **error);
  69
  70 void             g_dbus_connection_new_for_address            (const gchar            *address,
  71                                                                GDBusConnectionFlags    flags,
  72                                                                GDBusAuthObserver      *observer,
  73                                                                GCancellable           *cancellable,
  74                                                                GAsyncReadyCallback     callback,
  75                                                                gpointer                user_data);
  76 GDBusConnection *g_dbus_connection_new_for_address_finish     (GAsyncResult           *res,
  77                                                                GError                **error);
  78 GDBusConnection *g_dbus_connection_new_for_address_sync       (const gchar            *address,
  79                                                                GDBusConnectionFlags    flags,
  80                                                                GDBusAuthObserver      *observer,
  81                                                                GCancellable           *cancellable,
  82                                                                GError                **error);
  83
  84 /* ---------------------------------------------------------------------------------------------------- */
  85
  86 void             g_dbus_connection_start_message_processing   (GDBusConnection    *connection);
  87 gboolean         g_dbus_connection_is_closed                  (GDBusConnection    *connection);
  88 GIOStream       *g_dbus_connection_get_stream                 (GDBusConnection    *connection);
  89 const gchar     *g_dbus_connection_get_guid                   (GDBusConnection    *connection);
  90 const gchar     *g_dbus_connection_get_unique_name            (GDBusConnection    *connection);
  91 GCredentials    *g_dbus_connection_get_peer_credentials       (GDBusConnection    *connection);
  92 gboolean         g_dbus_connection_get_exit_on_close          (GDBusConnection    *connection);
  93 void             g_dbus_connection_set_exit_on_close          (GDBusConnection    *connection,
  94                                                                gboolean            exit_on_close);
  95 GDBusCapabilityFlags  g_dbus_connection_get_capabilities      (GDBusConnection    *connection);
  96
  97 /* ---------------------------------------------------------------------------------------------------- */
  98
  99 void             g_dbus_connection_close                          (GDBusConnection     *connection,
 100                                                                    GCancellable        *cancellable,
 101                                                                    GAsyncReadyCallback  callback,
 102                                                                    gpointer             user_data);
 103 gboolean         g_dbus_connection_close_finish                   (GDBusConnection     *connection,
 104                                                                    GAsyncResult        *res,
 105                                                                    GError             **error);
 106 gboolean         g_dbus_connection_close_sync                     (GDBusConnection     *connection,
 107                                                                    GCancellable        *cancellable,
 108                                                                    GError             **error);
 109
 110 /* ---------------------------------------------------------------------------------------------------- */
 111
 112 void             g_dbus_connection_flush                          (GDBusConnection     *connection,
 113                                                                    GCancellable        *cancellable,
 114                                                                    GAsyncReadyCallback  callback,
 115                                                                    gpointer             user_data);
 116 gboolean         g_dbus_connection_flush_finish                   (GDBusConnection     *connection,
 117                                                                    GAsyncResult        *res,
 118                                                                    GError             **error);
 119 gboolean         g_dbus_connection_flush_sync                     (GDBusConnection     *connection,
 120                                                                    GCancellable        *cancellable,
 121                                                                    GError             **error);
 122
 123 /* ---------------------------------------------------------------------------------------------------- */
 124
 125 gboolean         g_dbus_connection_send_message                   (GDBusConnection     *connection,
 126                                                                    GDBusMessage        *message,
 127                                                                    GDBusSendMessageFlags flags,
 128                                                                    volatile guint32    *out_serial,
 129                                                                    GError             **error);
 130 void             g_dbus_connection_send_message_with_reply        (GDBusConnection     *connection,
 131                                                                    GDBusMessage        *message,
 132                                                                    GDBusSendMessageFlags flags,
 133                                                                    gint                 timeout_msec,
 134                                                                    volatile guint32    *out_serial,
 135                                                                    GCancellable        *cancellable,
 136                                                                    GAsyncReadyCallback  callback,
 137                                                                    gpointer             user_data);
 138 GDBusMessage    *g_dbus_connection_send_message_with_reply_finish (GDBusConnection     *connection,
 139                                                                    GAsyncResult        *res,
 140                                                                    GError             **error);
 141 GDBusMessage    *g_dbus_connection_send_message_with_reply_sync   (GDBusConnection     *connection,
 142                                                                    GDBusMessage        *message,
 143                                                                    GDBusSendMessageFlags flags,
 144                                                                    gint                 timeout_msec,
 145                                                                    volatile guint32    *out_serial,
 146                                                                    GCancellable        *cancellable,
 147                                                                    GError             **error);
 148
 149 /* ---------------------------------------------------------------------------------------------------- */
 150
 151 gboolean  g_dbus_connection_emit_signal                       (GDBusConnection    *connection,
 152                                                                const gchar        *destination_bus_name,
 153                                                                const gchar        *object_path,
 154                                                                const gchar        *interface_name,
 155                                                                const gchar        *signal_name,
 156                                                                GVariant           *parameters,
 157                                                                GError            **error);
 158 void      g_dbus_connection_call                              (GDBusConnection    *connection,
 159                                                                const gchar        *bus_name,
 160                                                                const gchar        *object_path,
 161                                                                const gchar        *interface_name,
 162                                                                const gchar        *method_name,
 163                                                                GVariant           *parameters,
 164                                                                const GVariantType *reply_type,
 165                                                                GDBusCallFlags      flags,
 166                                                                gint                timeout_msec,
 167                                                                GCancellable       *cancellable,
 168                                                                GAsyncReadyCallback callback,
 169                                                                gpointer            user_data);
 170 GVariant *g_dbus_connection_call_finish                       (GDBusConnection    *connection,
 171                                                                GAsyncResult       *res,
 172                                                                GError            **error);
 173 GVariant *g_dbus_connection_call_sync                         (GDBusConnection    *connection,
 174                                                                const gchar        *bus_name,
 175                                                                const gchar        *object_path,
 176                                                                const gchar        *interface_name,
 177                                                                const gchar        *method_name,
 178                                                                GVariant           *parameters,
 179                                                                const GVariantType *reply_type,
 180                                                                GDBusCallFlags      flags,
 181                                                                gint                timeout_msec,
 182                                                                GCancellable       *cancellable,
 183                                                                GError            **error);
 184 GLIB_AVAILABLE_IN_2_30
 185 void      g_dbus_connection_call_with_unix_fd_list            (GDBusConnection    *connection,
 186                                                                const gchar        *bus_name,
 187                                                                const gchar        *object_path,
 188                                                                const gchar        *interface_name,
 189                                                                const gchar        *method_name,
 190                                                                GVariant           *parameters,
 191                                                                const GVariantType *reply_type,
 192                                                                GDBusCallFlags      flags,
 193                                                                gint                timeout_msec,
 194                                                                GUnixFDList        *fd_list,
 195                                                                GCancellable       *cancellable,
 196                                                                GAsyncReadyCallback callback,
 197                                                                gpointer            user_data);
 198 GLIB_AVAILABLE_IN_2_30
 199 GVariant *g_dbus_connection_call_with_unix_fd_list_finish     (GDBusConnection    *connection,
 200                                                                GUnixFDList       **out_fd_list,
 201                                                                GAsyncResult       *res,
 202                                                                GError            **error);
 203 GLIB_AVAILABLE_IN_2_30
 204 GVariant *g_dbus_connection_call_with_unix_fd_list_sync       (GDBusConnection    *connection,
 205                                                                const gchar        *bus_name,
 206                                                                const gchar        *object_path,
 207                                                                const gchar        *interface_name,
 208                                                                const gchar        *method_name,
 209                                                                GVariant           *parameters,
 210                                                                const GVariantType *reply_type,
 211                                                                GDBusCallFlags      flags,
 212                                                                gint                timeout_msec,
 213                                                                GUnixFDList        *fd_list,
 214                                                                GUnixFDList       **out_fd_list,
 215                                                                GCancellable       *cancellable,
 216                                                                GError            **error);
 217
 218 /* ---------------------------------------------------------------------------------------------------- */
 219
 220
 221 /**
 222  * GDBusInterfaceMethodCallFunc:
 223  * @connection: A #GDBusConnection.
 224  * @sender: The unique bus name of the remote caller.
 225  * @object_path: The object path that the method was invoked on.
 226  * @interface_name: The D-Bus interface name the method was invoked on.
 227  * @method_name: The name of the method that was invoked.
 228  * @parameters: A #GVariant tuple with parameters.
 229  * @invocation: A #GDBusMethodInvocation object that can be used to return a value or error.
 230  * @user_data: The @user_data #gpointer passed to g_dbus_connection_register_object().
 231  *
 232  * The type of the @method_call function in #GDBusInterfaceVTable.
 233  *
 234  * Since: 2.26
 235  */
 236 typedef void (*GDBusInterfaceMethodCallFunc) (GDBusConnection       *connection,
 237                                               const gchar           *sender,
 238                                               const gchar           *object_path,
 239                                               const gchar           *interface_name,
 240                                               const gchar           *method_name,
 241                                               GVariant              *parameters,
 242                                               GDBusMethodInvocation *invocation,
 243                                               gpointer               user_data);
 244
 245 /**
 246  * GDBusInterfaceGetPropertyFunc:
 247  * @connection: A #GDBusConnection.
 248  * @sender: The unique bus name of the remote caller.
 249  * @object_path: The object path that the method was invoked on.
 250  * @interface_name: The D-Bus interface name for the property.
 251  * @property_name: The name of the property to get the value of.
 252  * @error: Return location for error.
 253  * @user_data: The @user_data #gpointer passed to g_dbus_connection_register_object().
 254  *
 255  * The type of the @get_property function in #GDBusInterfaceVTable.
 256  *
 257  * Returns: A #GVariant with the value for @property_name or %NULL if
 258  *     @error is set. If the returned #GVariant is floating, it is
 259  *     consumed - otherwise its reference count is decreased by one.
 260  *
 261  * Since: 2.26
 262  */
 263 typedef GVariant *(*GDBusInterfaceGetPropertyFunc) (GDBusConnection       *connection,
 264                                                     const gchar           *sender,
 265                                                     const gchar           *object_path,
 266                                                     const gchar           *interface_name,
 267                                                     const gchar           *property_name,
 268                                                     GError               **error,
 269                                                     gpointer               user_data);
 270
 271 /**
 272  * GDBusInterfaceSetPropertyFunc:
 273  * @connection: A #GDBusConnection.
 274  * @sender: The unique bus name of the remote caller.
 275  * @object_path: The object path that the method was invoked on.
 276  * @interface_name: The D-Bus interface name for the property.
 277  * @property_name: The name of the property to get the value of.
 278  * @value: The value to set the property to.
 279  * @error: Return location for error.
 280  * @user_data: The @user_data #gpointer passed to g_dbus_connection_register_object().
 281  *
 282  * The type of the @set_property function in #GDBusInterfaceVTable.
 283  *
 284  * Returns: %TRUE if the property was set to @value, %FALSE if @error is set.
 285  *
 286  * Since: 2.26
 287  */
 288 typedef gboolean  (*GDBusInterfaceSetPropertyFunc) (GDBusConnection       *connection,
 289                                                     const gchar           *sender,
 290                                                     const gchar           *object_path,
 291                                                     const gchar           *interface_name,
 292                                                     const gchar           *property_name,
 293                                                     GVariant              *value,
 294                                                     GError               **error,
 295                                                     gpointer               user_data);
 296
 297 /**
 298  * GDBusInterfaceVTable:
 299  * @method_call: Function for handling incoming method calls.
 300  * @get_property: Function for getting a property.
 301  * @set_property: Function for setting a property.
 302  *
 303  * Virtual table for handling properties and method calls for a D-Bus
 304  * interface.
 305  *
 306  * If you want to handle getting/setting D-Bus properties asynchronously, simply
 307  * register an object with the <literal>org.freedesktop.DBus.Properties</literal>
 308  * D-Bus interface using g_dbus_connection_register_object().
 309  *
 310  * Since: 2.26
 311  */
 312 struct _GDBusInterfaceVTable
 313 {
 314   GDBusInterfaceMethodCallFunc  method_call;
 315   GDBusInterfaceGetPropertyFunc get_property;
 316   GDBusInterfaceSetPropertyFunc set_property;
 317
 318   /*< private >*/
 319   /* Padding for future expansion - also remember to update
 320    * gdbusconnection.c:_g_dbus_interface_vtable_copy() when
 321    * changing this.
 322    */
 323   gpointer padding[8];
 324 };
 325
 326 guint            g_dbus_connection_register_object            (GDBusConnection            *connection,
 327                                                                const gchar                *object_path,
 328                                                                GDBusInterfaceInfo         *interface_info,
 329                                                                const GDBusInterfaceVTable *vtable,
 330                                                                gpointer                    user_data,
 331                                                                GDestroyNotify              user_data_free_func,
 332                                                                GError                    **error);
 333 gboolean         g_dbus_connection_unregister_object          (GDBusConnection            *connection,
 334                                                                guint                       registration_id);
 335
 336 /* ---------------------------------------------------------------------------------------------------- */
 337
 338 /**
 339  * GDBusSubtreeEnumerateFunc:
 340  * @connection: A #GDBusConnection.
 341  * @sender: The unique bus name of the remote caller.
 342  * @object_path: The object path that was registered with g_dbus_connection_register_subtree().
 343  * @user_data: The @user_data #gpointer passed to g_dbus_connection_register_subtree().
 344  *
 345  * The type of the @enumerate function in #GDBusSubtreeVTable.
 346  *
 347  * This function is called when generating introspection data and also
 348  * when preparing to dispatch incoming messages in the event that the
 349  * %G_DBUS_SUBTREE_FLAGS_DISPATCH_TO_UNENUMERATED_NODES flag is not
 350  * specified (ie: to verify that the object path is valid).
 351  *
 352  * Hierarchies are not supported; the items that you return should not
 353  * contain the '/' character.
 354  *
 355  * The return value will be freed with g_strfreev().
 356  *
 357  * Returns: A newly allocated array of strings for node names that are children of @object_path.
 358  *
 359  * Since: 2.26
 360  */
 361 typedef gchar** (*GDBusSubtreeEnumerateFunc) (GDBusConnection       *connection,
 362                                               const gchar           *sender,
 363                                               const gchar           *object_path,
 364                                               gpointer               user_data);
 365
 366 /**
 367  * GDBusSubtreeIntrospectFunc:
 368  * @connection: A #GDBusConnection.
 369  * @sender: The unique bus name of the remote caller.
 370  * @object_path: The object path that was registered with g_dbus_connection_register_subtree().
 371  * @node: A node that is a child of @object_path (relative to @object_path) or %NULL for the root of the subtree.
 372  * @user_data: The @user_data #gpointer passed to g_dbus_connection_register_subtree().
 373  *
 374  * The type of the @introspect function in #GDBusSubtreeVTable.
 375  *
 376  * Subtrees are flat.  @node, if non-%NULL, is always exactly one
 377  * segment of the object path (ie: it never contains a slash).
 378  *
 379  * This function should return %NULL to indicate that there is no object
 380  * at this node.
 381  *
 382  * If this function returns non-%NULL, the return value is expected to
 383  * be a %NULL-terminated array of pointers to #GDBusInterfaceInfo
 384  * structures describing the interfaces implemented by @node.  This
 385  * array will have g_dbus_interface_info_unref() called on each item
 386  * before being freed with g_free().
 387  *
 388  * The difference between returning %NULL and an array containing zero
 389  * items is that the standard DBus interfaces will returned to the
 390  * remote introspector in the empty array case, but not in the %NULL
 391  * case.
 392  *
 393  * Returns: A %NULL-terminated array of pointers to #GDBusInterfaceInfo, or %NULL.
 394  *
 395  * Since: 2.26
 396  */
 397 typedef GDBusInterfaceInfo ** (*GDBusSubtreeIntrospectFunc) (GDBusConnection       *connection,
 398                                                              const gchar           *sender,
 399                                                              const gchar           *object_path,
 400                                                              const gchar           *node,
 401                                                              gpointer               user_data);
 402
 403 /**
 404  * GDBusSubtreeDispatchFunc:
 405  * @connection: A #GDBusConnection.
 406  * @sender: The unique bus name of the remote caller.
 407  * @object_path: The object path that was registered with g_dbus_connection_register_subtree().
 408  * @interface_name: The D-Bus interface name that the method call or property access is for.
 409  * @node: A node that is a child of @object_path (relative to @object_path) or %NULL for the root of the subtree.
 410  * @out_user_data: Return location for user data to pass to functions in the returned #GDBusInterfaceVTable (never %NULL).
 411  * @user_data: The @user_data #gpointer passed to g_dbus_connection_register_subtree().
 412  *
 413  * The type of the @dispatch function in #GDBusSubtreeVTable.
 414  *
 415  * Subtrees are flat.  @node, if non-%NULL, is always exactly one
 416  * segment of the object path (ie: it never contains a slash).
 417  *
 418  * Returns: A #GDBusInterfaceVTable or %NULL if you don't want to handle the methods.
 419  *
 420  * Since: 2.26
 421  */
 422 typedef const GDBusInterfaceVTable * (*GDBusSubtreeDispatchFunc) (GDBusConnection             *connection,
 423                                                                   const gchar                 *sender,
 424                                                                   const gchar                 *object_path,
 425                                                                   const gchar                 *interface_name,
 426                                                                   const gchar                 *node,
 427                                                                   gpointer                    *out_user_data,
 428                                                                   gpointer                     user_data);
 429
 430 /**
 431  * GDBusSubtreeVTable:
 432  * @enumerate: Function for enumerating child nodes.
 433  * @introspect: Function for introspecting a child node.
 434  * @dispatch: Function for dispatching a remote call on a child node.
 435  *
 436  * Virtual table for handling subtrees registered with g_dbus_connection_register_subtree().
 437  *
 438  * Since: 2.26
 439  */
 440 struct _GDBusSubtreeVTable
 441 {
 442   GDBusSubtreeEnumerateFunc  enumerate;
 443   GDBusSubtreeIntrospectFunc introspect;
 444   GDBusSubtreeDispatchFunc   dispatch;
 445
 446   /*< private >*/
 447   /* Padding for future expansion - also remember to update
 448    * gdbusconnection.c:_g_dbus_subtree_vtable_copy() when
 449    * changing this.
 450    */
 451   gpointer padding[8];
 452 };
 453
 454 guint            g_dbus_connection_register_subtree           (GDBusConnection            *connection,
 455                                                                const gchar                *object_path,
 456                                                                const GDBusSubtreeVTable   *vtable,
 457                                                                GDBusSubtreeFlags           flags,
 458                                                                gpointer                    user_data,
 459                                                                GDestroyNotify              user_data_free_func,
 460                                                                GError                    **error);
 461 gboolean         g_dbus_connection_unregister_subtree         (GDBusConnection            *connection,
 462                                                                guint                       registration_id);
 463
 464 /* ---------------------------------------------------------------------------------------------------- */
 465
 466 /**
 467  * GDBusSignalCallback:
 468  * @connection: A #GDBusConnection.
 469  * @sender_name: The unique bus name of the sender of the signal.
 470  * @object_path: The object path that the signal was emitted on.
 471  * @interface_name: The name of the interface.
 472  * @signal_name: The name of the signal.
 473  * @parameters: A #GVariant tuple with parameters for the signal.
 474  * @user_data: User data passed when subscribing to the signal.
 475  *
 476  * Signature for callback function used in g_dbus_connection_signal_subscribe().
 477  *
 478  * Since: 2.26
 479  */
 480 typedef void (*GDBusSignalCallback) (GDBusConnection  *connection,
 481                                      const gchar      *sender_name,
 482                                      const gchar      *object_path,
 483                                      const gchar      *interface_name,
 484                                      const gchar      *signal_name,
 485                                      GVariant         *parameters,
 486                                      gpointer          user_data);
 487
 488 guint            g_dbus_connection_signal_subscribe           (GDBusConnection     *connection,
 489                                                                const gchar         *sender,
 490                                                                const gchar         *interface_name,
 491                                                                const gchar         *member,
 492                                                                const gchar         *object_path,
 493                                                                const gchar         *arg0,
 494                                                                GDBusSignalFlags     flags,
 495                                                                GDBusSignalCallback  callback,
 496                                                                gpointer             user_data,
 497                                                                GDestroyNotify       user_data_free_func);
 498 void             g_dbus_connection_signal_unsubscribe         (GDBusConnection     *connection,
 499                                                                guint                subscription_id);
 500
 501 /* ---------------------------------------------------------------------------------------------------- */
 502
 503 /**
 504  * GDBusMessageFilterFunction:
 505  * @connection: (transfer none): A #GDBusConnection.
 506  * @message: (transfer full): A locked #GDBusMessage that the filter function takes ownership of.
 507  * @incoming: %TRUE if it is a message received from the other peer, %FALSE if it is
 508  * a message to be sent to the other peer.
 509  * @user_data: User data passed when adding the filter.
 510  *
 511  * Signature for function used in g_dbus_connection_add_filter().
 512  *
 513  * A filter function is passed a #GDBusMessage and expected to return
 514  * a #GDBusMessage too. Passive filter functions that don't modify the
 515  * message can simply return the @message object:
 516  * |[
 517  * static GDBusMessage *
 518  * passive_filter (GDBusConnection *connection
 519  *                 GDBusMessage    *message,
 520  *                 gboolean         incoming,
 521  *                 gpointer         user_data)
 522  * {
 523  *   /<!-- -->* inspect @message *<!-- -->/
 524  *   return message;
 525  * }
 526  * ]|
 527  * Filter functions that wants to drop a message can simply return %NULL:
 528  * |[
 529  * static GDBusMessage *
 530  * drop_filter (GDBusConnection *connection
 531  *              GDBusMessage    *message,
 532  *              gboolean         incoming,
 533  *              gpointer         user_data)
 534  * {
 535  *   if (should_drop_message)
 536  *     {
 537  *       g_object_unref (message);
 538  *       message = NULL;
 539  *     }
 540  *   return message;
 541  * }
 542  * ]|
 543  * Finally, a filter function may modify a message by copying it:
 544  * |[
 545  * static GDBusMessage *
 546  * modifying_filter (GDBusConnection *connection
 547  *                   GDBusMessage    *message,
 548  *                   gboolean         incoming,
 549  *                   gpointer         user_data)
 550  * {
 551  *   GDBusMessage *copy;
 552  *   GError *error;
 553  *
 554  *   error = NULL;
 555  *   copy = g_dbus_message_copy (message, &error);
 556  *   /<!-- -->* handle @error being is set *<!-- -->/
 557  *   g_object_unref (message);
 558  *
 559  *   /<!-- -->* modify @copy *<!-- -->/
 560  *
 561  *   return copy;
 562  * }
 563  * ]|
 564  * If the returned #GDBusMessage is different from @message and cannot
 565  * be sent on @connection (it could use features, such as file
 566  * descriptors, not compatible with @connection), then a warning is
 567  * logged to <emphasis>standard error</emphasis>. Applications can
 568  * check this ahead of time using g_dbus_message_to_blob() passing a
 569  * #GDBusCapabilityFlags value obtained from @connection.
 570  *
 571  * Returns: (transfer full) (allow-none): A #GDBusMessage that will be freed with
 572  * g_object_unref() or %NULL to drop the message. Passive filter
 573  * functions can simply return the passed @message object.
 574  *
 575  * Since: 2.26
 576  */
 577 typedef GDBusMessage *(*GDBusMessageFilterFunction) (GDBusConnection *connection,
 578                                                      GDBusMessage    *message,
 579                                                      gboolean         incoming,
 580                                                      gpointer         user_data);
 581
 582 guint g_dbus_connection_add_filter (GDBusConnection            *connection,
 583                                     GDBusMessageFilterFunction  filter_function,
 584                                     gpointer                    user_data,
 585                                     GDestroyNotify              user_data_free_func);
 586
 587 void  g_dbus_connection_remove_filter (GDBusConnection    *connection,
 588                                        guint               filter_id);
 589
 590 /* ---------------------------------------------------------------------------------------------------- */
 591
 592
 593 G_END_DECLS
 594
 595 #endif /* __G_DBUS_CONNECTION_H__ */