path: root/glib/dbus-gproxy.c

/* -*- mode: C; c-file-style: "gnu" -*- */
/* dbus-gcall.c convenience routines for calling methods, etc.
 *
 * Copyright (C) 2003, 2004 Red Hat, Inc.
 *
 * Licensed under the Academic Free License version 2.1
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
#include <dbus/dbus-glib.h>
#include <dbus/dbus-glib-lowlevel.h>
#include "dbus-gutils.h"
#include <string.h>

/**
 * @addtogroup DBusGLibInternals
 *
 * @{
 */

/**
 * DBusGProxyManager typedef
 */

typedef struct DBusGProxyManager DBusGProxyManager;

/**
 * Internals of DBusGProxy
 */
struct DBusGProxy
{
  GObject parent;             /**< Parent instance */
  
  DBusGProxyManager *manager; /**< Proxy manager */
  char *service;              /**< Service messages go to or NULL */
  char *path;                 /**< Path messages go to or NULL */
  char *interface;            /**< Interface messages go to or NULL */
};

/**
 * Class struct for DBusGProxy
 */
struct DBusGProxyClass
{
  GObjectClass parent_class;  /**< Parent class */
};

static void dbus_g_proxy_init          (DBusGProxy      *proxy);
static void dbus_g_proxy_class_init    (DBusGProxyClass *klass);
static void dbus_g_proxy_finalize      (GObject         *object);
static void dbus_g_proxy_dispose       (GObject         *object);
static void dbus_g_proxy_destroy       (DBusGProxy      *proxy);
static void dbus_g_proxy_emit_received (DBusGProxy      *proxy,
                                       DBusMessage     *message);


/**
 * A list of proxies with a given service+path+interface, used to
 * route incoming signals.
 */
typedef struct
{
  GSList *proxies; /**< The list of proxies */

  char name[4]; /**< service (empty string for none), nul byte,
                 *   path, nul byte,
                 *   interface, nul byte
                 */
  
} DBusGProxyList;

/**
 * DBusGProxyManager's primary task is to route signals to the proxies
 * those signals are emitted on. In order to do this it also has to
 * track the owners of the services proxies are bound to.
 */
struct DBusGProxyManager
{
  GStaticMutex lock; /**< Thread lock */
  int refcount;      /**< Reference count */
  DBusConnection *connection; /**< Connection we're associated with. */

  GHashTable *proxy_lists; /**< Hash used to route incoming signals
                            *   and iterate over proxies
                            */

};

static DBusGProxyManager *dbus_g_proxy_manager_ref    (DBusGProxyManager *manager);
static DBusHandlerResult dbus_g_proxy_manager_filter (DBusConnection    *connection,
                                                     DBusMessage       *message,
                                                     void              *user_data);

/** Lock the DBusGProxyManager */
#define LOCK_MANAGER(mgr)   (g_static_mutex_lock (&(mgr)->lock))
/** Unlock the DBusGProxyManager */
#define UNLOCK_MANAGER(mgr) (g_static_mutex_unlock (&(mgr)->lock))

static int g_proxy_manager_slot = -1;

/* Lock controlling get/set manager as data on each connection */
static GStaticMutex connection_g_proxy_lock = G_STATIC_MUTEX_INIT;

static DBusGProxyManager*
dbus_g_proxy_manager_get (DBusConnection *connection)
{
  DBusGProxyManager *manager;

  dbus_connection_allocate_data_slot (&g_proxy_manager_slot);
  if (g_proxy_manager_slot < 0)
    g_error ("out of memory");
  
  g_static_mutex_lock (&connection_g_proxy_lock);
  
  manager = dbus_connection_get_data (connection, g_proxy_manager_slot);
  if (manager != NULL)
    {
      dbus_connection_free_data_slot (&g_proxy_manager_slot);
      dbus_g_proxy_manager_ref (manager);
      g_static_mutex_unlock (&connection_g_proxy_lock);
      return manager;
    }
  
  manager = g_new0 (DBusGProxyManager, 1);

  manager->refcount = 1;
  manager->connection = connection;
  
  g_static_mutex_init (&manager->lock);

  /* Proxy managers keep the connection alive, which means that
   * DBusGProxy indirectly does. To free a connection you have to free
   * all the proxies referring to it.
   */
  dbus_connection_ref (manager->connection);

  dbus_connection_set_data (connection, g_proxy_manager_slot,
                            manager, NULL);

  dbus_connection_add_filter (connection, dbus_g_proxy_manager_filter,
                              manager, NULL);
  
  g_static_mutex_unlock (&connection_g_proxy_lock);
  
  return manager;
}

static DBusGProxyManager * 
dbus_g_proxy_manager_ref (DBusGProxyManager *manager)
{
  g_assert (manager != NULL);
  g_assert (manager->refcount > 0);

  LOCK_MANAGER (manager);
  
  manager->refcount += 1;

  UNLOCK_MANAGER (manager);

  return manager;
}

static void
dbus_g_proxy_manager_unref (DBusGProxyManager *manager)
{
  g_assert (manager != NULL);
  g_assert (manager->refcount > 0);

  LOCK_MANAGER (manager);
  manager->refcount -= 1;
  if (manager->refcount == 0)
    {
      UNLOCK_MANAGER (manager);

      if (manager->proxy_lists)
        {
          /* can't have any proxies left since they hold
           * a reference to the proxy manager.
           */
          g_assert (g_hash_table_size (manager->proxy_lists) == 0);
          
          g_hash_table_destroy (manager->proxy_lists);
          manager->proxy_lists = NULL;
        }
      
      g_static_mutex_free (&manager->lock);

      g_static_mutex_lock (&connection_g_proxy_lock);

      dbus_connection_remove_filter (manager->connection, dbus_g_proxy_manager_filter,
                                     manager);
      
      dbus_connection_set_data (manager->connection,
                                g_proxy_manager_slot,
                                NULL, NULL);

      g_static_mutex_unlock (&connection_g_proxy_lock);
      
      dbus_connection_unref (manager->connection);
      g_free (manager);

      dbus_connection_free_data_slot (&g_proxy_manager_slot);
    }
  else
    {
      UNLOCK_MANAGER (manager);
    }
}

static guint
tristring_hash (gconstpointer key)
{
  const char *p = key;
  guint h = *p;

  if (h)
    {
      for (p += 1; *p != '\0'; p++)
        h = (h << 5) - h + *p;
    }

  /* skip nul and do the next substring */
  for (p += 1; *p != '\0'; p++)
    h = (h << 5) - h + *p;

  /* skip nul again and another substring */
  for (p += 1; *p != '\0'; p++)
    h = (h << 5) - h + *p;
  
  return h;
}

static gboolean
strequal_len (const char *a,
              const char *b,
              size_t     *lenp)
{
  size_t a_len;
  size_t b_len;

  a_len = strlen (a);
  b_len = strlen (b);

  if (a_len != b_len)
    return FALSE;

  if (memcmp (a, b, a_len) != 0)
    return FALSE;
  
  *lenp = a_len;

  return TRUE;
}

static gboolean
tristring_equal (gconstpointer  a,
                 gconstpointer  b)
{
  const char *ap = a;
  const char *bp = b;
  size_t len;

  if (!strequal_len (ap, bp, &len))
    return FALSE;

  ap += len + 1;
  bp += len + 1;

  if (!strequal_len (ap, bp, &len))
    return FALSE;

  ap += len + 1;
  bp += len + 1;

  if (strcmp (ap, bp) != 0)
    return FALSE;
  
  return TRUE;
}

static char*
tristring_alloc_from_strings (size_t      padding_before,
                              const char *service,
                              const char *path,
                              const char *interface)
{
  size_t service_len, iface_len, path_len, len;
  char *tri;
  
  if (service)
    service_len = strlen (service);
  else
    service_len = 0;

  path_len = strlen (path);
  
  iface_len = strlen (interface);

  tri = g_malloc (padding_before + service_len + path_len + iface_len + 3);

  len = padding_before;
  
  if (service)
    memcpy (&tri[len], service, service_len);

  len += service_len;
  tri[len] = '\0';
  len += 1;

  g_assert (len == (padding_before + service_len + 1));
  
  memcpy (&tri[len], path, path_len);
  len += path_len;
  tri[len] = '\0';
  len += 1;

  g_assert (len == (padding_before + service_len + path_len + 2));
  
  memcpy (&tri[len], interface, iface_len);
  len += iface_len;
  tri[len] = '\0';
  len += 1;

  g_assert (len == (padding_before + service_len + path_len + iface_len + 3));

  return tri;
}

static char*
tristring_from_proxy (DBusGProxy *proxy)
{
  return tristring_alloc_from_strings (0,
                                       proxy->service,
                                       proxy->path,
                                       proxy->interface);
}

static char*
tristring_from_message (DBusMessage *message)
{
  return tristring_alloc_from_strings (0,
                                       dbus_message_get_sender (message),
                                       dbus_message_get_path (message),
                                       dbus_message_get_interface (message));
}

static DBusGProxyList*
g_proxy_list_new (DBusGProxy *first_proxy)
{
  DBusGProxyList *list;
  
  list = (void*) tristring_alloc_from_strings (G_STRUCT_OFFSET (DBusGProxyList, name),
                                               first_proxy->service,
                                               first_proxy->path,
                                               first_proxy->interface);
  list->proxies = NULL;

  return list;
}

static void
g_proxy_list_free (DBusGProxyList *list)
{
  /* we don't hold a reference to the proxies in the list,
   * as they ref the GProxyManager
   */
  g_slist_free (list->proxies);  

  g_free (list);
}

static char*
g_proxy_get_match_rule (DBusGProxy *proxy)
{
  /* FIXME Escaping is required here */
  
  if (proxy->service)
    return g_strdup_printf ("type='signal',sender='%s',path='%s',interface='%s'",
                            proxy->service, proxy->path, proxy->interface);
  else
    return g_strdup_printf ("type='signal',path='%s',interface='%s'",
                            proxy->path, proxy->interface);
}

static void
dbus_g_proxy_manager_register (DBusGProxyManager *manager,
                              DBusGProxy        *proxy)
{
  DBusGProxyList *list;

  LOCK_MANAGER (manager);

  if (manager->proxy_lists == NULL)
    {
      list = NULL;
      manager->proxy_lists = g_hash_table_new_full (tristring_hash,
                                                    tristring_equal,
                                                    NULL,
                                                    (GFreeFunc) g_proxy_list_free);
    }
  else
    {
      char *tri;

      tri = tristring_from_proxy (proxy);
      
      list = g_hash_table_lookup (manager->proxy_lists, tri);

      g_free (tri);
    }
      
  if (list == NULL)
    {
      list = g_proxy_list_new (proxy);
      
      g_hash_table_replace (manager->proxy_lists,
                            list->name, list);
    }

  if (list->proxies == NULL)
    {
      /* We have to add the match rule to the server,
       * but FIXME only if the server is a message bus,
       * not if it's a peer.
       */
      char *rule;

      rule = g_proxy_get_match_rule (proxy);
      
      /* We don't check for errors; it's not like anyone would handle them,
       * and we don't want a round trip here.
       */
      dbus_bus_add_match (manager->connection,
                          rule, NULL);

      g_free (rule);
    }

  g_assert (g_slist_find (list->proxies, proxy) == NULL);
  
  list->proxies = g_slist_prepend (list->proxies, proxy);
  
  UNLOCK_MANAGER (manager);
}

static void
dbus_g_proxy_manager_unregister (DBusGProxyManager *manager,
                                DBusGProxy        *proxy)
{
  DBusGProxyList *list;
  char *tri;
  
  LOCK_MANAGER (manager);

#ifndef G_DISABLE_CHECKS
  if (manager->proxy_lists == NULL)
    {
      g_warning ("Trying to unregister a proxy but there aren't any registered");
      return;
    }
#endif

  tri = tristring_from_proxy (proxy);
  
  list = g_hash_table_lookup (manager->proxy_lists, tri);

#ifndef G_DISABLE_CHECKS
  if (list == NULL)
    {
      g_warning ("Trying to unregister a proxy but it isn't registered");
      return;
    }
#endif

  g_assert (g_slist_find (list->proxies, proxy) != NULL);
  
  list->proxies = g_slist_remove (list->proxies, proxy);

  g_assert (g_slist_find (list->proxies, proxy) == NULL);

  if (list->proxies == NULL)
    {
      g_hash_table_remove (manager->proxy_lists,
                           tri);
      list = NULL;
    }
  
  if (g_hash_table_size (manager->proxy_lists) == 0)
    {
      g_hash_table_destroy (manager->proxy_lists);
      manager->proxy_lists = NULL;
    }

  g_free (tri);
      
  UNLOCK_MANAGER (manager);
}

static void
list_proxies_foreach (gpointer key,
                      gpointer value,
                      gpointer user_data)
{
  DBusGProxyList *list;
  GSList **ret;
  GSList *tmp;
  
  list = value;
  ret = user_data;

  tmp = list->proxies;
  while (tmp != NULL)
    {
      DBusGProxy *proxy = DBUS_G_PROXY (tmp->data);

      g_object_ref (proxy);
      *ret = g_slist_prepend (*ret, proxy);
      
      tmp = tmp->next;
    }
}

static GSList*
dbus_g_proxy_manager_list_all (DBusGProxyManager *manager)
{
  GSList *ret;

  ret = NULL;

  if (manager->proxy_lists)
    {
      g_hash_table_foreach (manager->proxy_lists,
                            list_proxies_foreach,
                            &ret);
    }

  return ret;
}

static DBusHandlerResult
dbus_g_proxy_manager_filter (DBusConnection    *connection,
                            DBusMessage       *message,
                            void              *user_data)
{
  DBusGProxyManager *manager;
  
  if (dbus_message_get_type (message) != DBUS_MESSAGE_TYPE_SIGNAL)
    return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;

  manager = user_data;

  dbus_g_proxy_manager_ref (manager);
  
  LOCK_MANAGER (manager);
  
  if (dbus_message_is_signal (message,
                              DBUS_INTERFACE_ORG_FREEDESKTOP_LOCAL,
                              "Disconnected"))
    {
      /* Destroy all the proxies, quite possibly resulting in unreferencing
       * the proxy manager and the connection as well.
       */
      GSList *all;
      GSList *tmp;

      all = dbus_g_proxy_manager_list_all (manager);

      tmp = all;
      while (tmp != NULL)
        {
          DBusGProxy *proxy;

          proxy = DBUS_G_PROXY (tmp->data);

          UNLOCK_MANAGER (manager);
          dbus_g_proxy_destroy (proxy);
          g_object_unref (G_OBJECT (proxy));
          LOCK_MANAGER (manager);
          
          tmp = tmp->next;
        }

      g_slist_free (all);

#ifndef G_DISABLE_CHECKS
      if (manager->proxy_lists != NULL)
        g_warning ("Disconnection emitted \"destroy\" on all DBusGProxy, but somehow new proxies were created in response to one of those destroy signals. This will cause a memory leak.");
#endif
    }
  else
    {
      char *tri;
      DBusGProxyList *list;
      
      tri = tristring_from_message (message);

      if (manager->proxy_lists)
        list = g_hash_table_lookup (manager->proxy_lists, tri);
      else
        list = NULL;

#if 0
      g_print ("proxy got %s,%s,%s = list %p\n",
               tri,
               tri + strlen (tri) + 1,
               tri + strlen (tri) + 1 + strlen (tri + strlen (tri) + 1) + 1,
               list);
#endif
      
      g_free (tri);

      /* Emit the signal */
      
      if (list != NULL)
        {
          GSList *tmp;
          GSList *copy;

          copy = g_slist_copy (list->proxies);
          g_slist_foreach (copy, (GFunc) g_object_ref, NULL);
          
          tmp = copy;
          while (tmp != NULL)
            {
              DBusGProxy *proxy;

              proxy = DBUS_G_PROXY (tmp->data);

              UNLOCK_MANAGER (manager);
              dbus_g_proxy_emit_received (proxy, message);
              g_object_unref (G_OBJECT (proxy));
              LOCK_MANAGER (manager);
              
              tmp = tmp->next;
            }

          g_slist_free (copy);
        }
    }

  UNLOCK_MANAGER (manager);
  dbus_g_proxy_manager_unref (manager);
  
  /* "Handling" signals doesn't make sense, they are for everyone
   * who cares
   */
  return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
}



/*      ---------- DBusGProxy --------------   */



enum
{
  DESTROY,
  RECEIVED,
  LAST_SIGNAL
};

static void *parent_class;
static guint signals[LAST_SIGNAL] = { 0 };

static void
dbus_g_proxy_init (DBusGProxy *proxy)
{
  /* Nothing */
}

static void
dbus_g_proxy_class_init (DBusGProxyClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);
  
  parent_class = g_type_class_peek_parent (klass);
  
  object_class->finalize = dbus_g_proxy_finalize;
  object_class->dispose = dbus_g_proxy_dispose;
  
  signals[DESTROY] =
    g_signal_new ("destroy",
		  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_CLEANUP | G_SIGNAL_NO_RECURSE | G_SIGNAL_NO_HOOKS,
                  0,
		  NULL, NULL,
                  g_cclosure_marshal_VOID__VOID,
		  G_TYPE_NONE, 0);
  
  signals[RECEIVED] =
    g_signal_new ("received",
		  G_OBJECT_CLASS_TYPE (object_class),
		  G_SIGNAL_RUN_LAST | G_SIGNAL_DETAILED,
                  0,
		  NULL, NULL,
                  g_cclosure_marshal_VOID__BOXED,
		  G_TYPE_NONE, 1,
                  DBUS_TYPE_MESSAGE);
}


static void
dbus_g_proxy_dispose (GObject *object)
{
  DBusGProxy *proxy;

  proxy = DBUS_G_PROXY (object);

  g_signal_emit (object, signals[DESTROY], 0);
  
  G_OBJECT_CLASS (parent_class)->dispose (object);
}

static void
dbus_g_proxy_finalize (GObject *object)
{
  DBusGProxy *proxy;

  proxy = DBUS_G_PROXY (object);

  if (proxy->manager)
    {
      dbus_g_proxy_manager_unregister (proxy->manager, proxy);
      dbus_g_proxy_manager_unref (proxy->manager);
    }
  
  g_free (proxy->service);
  g_free (proxy->path);
  g_free (proxy->interface);
  
  G_OBJECT_CLASS (parent_class)->finalize (object);
}

static void
dbus_g_proxy_destroy (DBusGProxy *proxy)
{
  /* FIXME do we need the GTK_IN_DESTRUCTION style flag
   * from GtkObject?
   */
  g_object_run_dispose (G_OBJECT (proxy));
}

static char*
create_signal_detail (const char *interface,
                      const char *signal)
{
  GString *str;

  str = g_string_new (interface);

  g_string_append (str, ".");

  g_string_append (str, signal);

  return g_string_free (str, FALSE);
}

static void
dbus_g_proxy_emit_received (DBusGProxy  *proxy,
                           DBusMessage *message)
{
  const char *interface;
  const char *signal;
  char *detail;
  GQuark q;
  
  interface = dbus_message_get_interface (message);
  signal = dbus_message_get_member (message);

  g_assert (interface != NULL);
  g_assert (signal != NULL);

  detail = create_signal_detail (interface, signal);

  /* If the quark isn't preexisting, there's no way there
   * are any handlers connected. We don't want to create
   * extra quarks for every possible signal.
   */
  q = g_quark_try_string (detail);

  if (q != 0)
    g_signal_emit (G_OBJECT (proxy),
                   signals[RECEIVED],
                   q,
                   message);

  g_free (detail);
}

/** @} End of DBusGLibInternals */

/** @addtogroup DBusGLib
 * @{
 */

/**
 * Standard GObject get_type() function for DBusGProxy.
 *
 * @returns type ID for DBusGProxy class
 */
GType
dbus_g_proxy_get_type (void)
{
  static GType object_type = 0;

  if (!object_type)
    {
      static const GTypeInfo object_info =
        {
          sizeof (DBusGProxyClass),
          (GBaseInitFunc) NULL,
          (GBaseFinalizeFunc) NULL,
          (GClassInitFunc) dbus_g_proxy_class_init,
          NULL,           /* class_finalize */
          NULL,           /* class_data */
          sizeof (DBusGProxy),
          0,              /* n_preallocs */
          (GInstanceInitFunc) dbus_g_proxy_init,
        };
      
      object_type = g_type_register_static (G_TYPE_OBJECT,
                                            "DBusGProxy",
                                            &object_info, 0);
    }
  
  return object_type;
}

static DBusGProxy*
dbus_g_proxy_new (DBusGConnection *connection,
                 const char      *service_name,
                 const char      *path_name,
                 const char      *interface_name)
{
  DBusGProxy *proxy;

  g_assert (connection != NULL);
  
  proxy = g_object_new (DBUS_TYPE_G_PROXY, NULL);

  /* These should all be construct-only mandatory properties,
   * for now we just don't let people use g_object_new().
   */
  
  proxy->manager = dbus_g_proxy_manager_get (DBUS_CONNECTION_FROM_G_CONNECTION (connection));
  
  proxy->service = g_strdup (service_name);
  proxy->path = g_strdup (path_name);
  proxy->interface = g_strdup (interface_name);

  dbus_g_proxy_manager_register (proxy->manager, proxy);
  
  return proxy;
}

/**
 * Creates a new proxy for a remote interface exported by a service on
 * a message bus. Method calls and signal connections over this proxy
 * will go to the service owner; the service owner is expected to
 * support the given interface name. THE SERVICE OWNER MAY CHANGE OVER
 * TIME, for example between two different method calls. If you need a
 * fixed owner, you need to request the current owner and bind a proxy
 * to that rather than to the generic service name; see
 * dbus_g_proxy_new_for_service_owner().
 *
 * A service-associated proxy only makes sense with a message bus,
 * not for app-to-app direct dbus connections.
 *
 * This proxy will only emit the "destroy" signal if the #DBusConnection
 * is disconnected or the proxy is has no remaining references.
 *
 * @param connection the connection to the remote bus
 * @param service_name name of the service on the message bus
 * @param path_name name of the object inside the service to call methods on
 * @param interface_name name of the interface to call methods on
 * @returns new proxy object
 */
DBusGProxy*
dbus_g_proxy_new_for_service (DBusGConnection *connection,
                             const char      *service_name,
                             const char      *path_name,
                             const char      *interface_name)
{
  DBusGProxy *proxy;

  g_return_val_if_fail (connection != NULL, NULL);
  g_return_val_if_fail (service_name != NULL, NULL);
  g_return_val_if_fail (path_name != NULL, NULL);
  g_return_val_if_fail (interface_name != NULL, NULL);
  
  proxy = dbus_g_proxy_new (connection, service_name,
                            path_name, interface_name);

  return proxy;
}

/**
 * Similar to dbus_g_proxy_new_for_service(), but makes a round-trip
 * request to the message bus to get the current service owner, then
 * binds the proxy specifically to the current owner. As a result, the
 * service owner will not change over time, and the proxy will emit
 * the "destroy" signal when the owner disappears from the message
 * bus.
 *
 * An example of the difference between dbus_g_proxy_new_for_service()
 * and dbus_g_proxy_new_for_service_owner(): if you pass the service name
 * "org.freedesktop.Database" dbus_g_proxy_new_for_service() remains bound
 * to that name as it changes owner. dbus_g_proxy_new_for_service_owner()
 * will fail if the service has no owner. If the service has an owner,
 * dbus_g_proxy_new_for_service_owner() will bind to the unique name
 * of that owner rather than the generic service name.
 * 
 * @param connection the connection to the remote bus
 * @param service_name name of the service on the message bus
 * @param path_name name of the object inside the service to call methods on
 * @param interface_name name of the interface to call methods on
 * @param error return location for an error
 * @returns new proxy object, or #NULL on error
 */
DBusGProxy*
dbus_g_proxy_new_for_service_owner (DBusGConnection          *connection,
                                   const char               *service_name,
                                   const char               *path_name,
                                   const char               *interface_name,
                                   GError                  **error)
{
  DBusGProxy *proxy;
  DBusMessage *request, *reply;
  DBusError derror;
  char *base_service_name;

  g_return_val_if_fail (connection != NULL, NULL);
  g_return_val_if_fail (service_name != NULL, NULL);
  g_return_val_if_fail (path_name != NULL, NULL);
  g_return_val_if_fail (interface_name != NULL, NULL);

  dbus_error_init (&derror);

  proxy = NULL;
  base_service_name = NULL;
  reply = NULL;

  request = dbus_message_new_method_call (DBUS_SERVICE_ORG_FREEDESKTOP_DBUS,
					  DBUS_PATH_ORG_FREEDESKTOP_DBUS,
					  DBUS_INTERFACE_ORG_FREEDESKTOP_DBUS,
					  "GetServiceOwner");
  if (request == NULL)
    g_error ("Out of memory");
  
  if (! dbus_message_append_args (request, 
				  DBUS_TYPE_STRING, service_name, 
				  DBUS_TYPE_INVALID))
    g_error ("Out of memory");

  reply =
    dbus_connection_send_with_reply_and_block (DBUS_CONNECTION_FROM_G_CONNECTION (connection),
                                               request,
                                               2000, &derror);
  if (reply == NULL)
    goto error;

  if (dbus_set_error_from_message (&derror, reply))
    goto error;

  if (! dbus_message_get_args (reply, &derror, 
			       DBUS_TYPE_STRING, &base_service_name, 
			       DBUS_TYPE_INVALID))
    goto error;
      

  proxy = dbus_g_proxy_new (connection, base_service_name,
                           path_name, interface_name);

  goto out;

 error:
  g_assert (dbus_error_is_set (&derror));
  dbus_set_g_error (error, &derror);
  dbus_error_free (&derror);

 out:
  if (request)
    dbus_message_unref (request);
  if (reply)
    dbus_message_unref (reply);
  dbus_free (base_service_name);

  return proxy;
}

/**
 * Creates a proxy for an object in peer application (one
 * we're directly connected to). That is, this function is
 * intended for use when there's no message bus involved,
 * we're doing a simple 1-to-1 communication between two
 * applications.
 *
 *
 * @param connection the connection to the peer
 * @param path_name name of the object inside the peer to call methods on
 * @param interface_name name of the interface to call methods on
 * @returns new proxy object
 * 
 */
DBusGProxy*
dbus_g_proxy_new_for_peer (DBusGConnection          *connection,
                          const char               *path_name,
                          const char               *interface_name)
{
  DBusGProxy *proxy;
  
  g_return_val_if_fail (connection != NULL, NULL);
  g_return_val_if_fail (path_name != NULL, NULL);
  g_return_val_if_fail (interface_name != NULL, NULL);

  proxy = dbus_g_proxy_new (connection, NULL,
                           path_name, interface_name);

  return proxy;
}

/**
 * Invokes a method on a remote interface. This function does not
 * block; instead it returns an opaque #DBusPendingCall object that
 * tracks the pending call.  The method call will not be sent over the
 * wire until the application returns to the main loop, or blocks in
 * dbus_connection_flush() to write out pending data.  The call will
 * be completed after a timeout, or when a reply is received.
 * To collect the results of the call (which may be an error,
 * or a reply), use dbus_g_proxy_end_call().
 *
 * @todo this particular function shouldn't die on out of memory,
 * since you should be able to do a call with large arguments.
 * 
 * @param proxy a proxy for a remote interface
 * @param method the name of the method to invoke
 * @param first_arg_type type of the first argument
 *
 * @returns opaque pending call object
 *  */
DBusGPendingCall*
dbus_g_proxy_begin_call (DBusGProxy *proxy,
                        const char *method,
                        int         first_arg_type,
                        ...)
{
  DBusPendingCall *pending;
  DBusMessage *message;
  va_list args;
  
  g_return_val_if_fail (DBUS_IS_G_PROXY (proxy), NULL);

  message = dbus_message_new_method_call (proxy->service,
                                          proxy->path,
                                          proxy->interface,
                                          method);
  if (message == NULL)
    goto oom;

  va_start (args, first_arg_type);
  if (!dbus_message_append_args_valist (message, first_arg_type,
                                        args))
    goto oom;
  va_end (args);

  if (!dbus_connection_send_with_reply (proxy->manager->connection,
                                        message,
                                        &pending,
                                        -1))
    goto oom;

  return DBUS_G_PENDING_CALL_FROM_PENDING_CALL (pending);

 oom:
  /* FIXME we should create a pending call that's
   * immediately completed with an error status without
   * ever going on the wire.
   */
  
  g_error ("Out of memory");
  return NULL;
}

/**
 * Collects the results of a method call. The method call was normally
 * initiated with dbus_g_proxy_end_call(). This function will block if
 * the results haven't yet been received; use
 * dbus_pending_call_set_notify() to be notified asynchronously that a
 * pending call has been completed. Use
 * dbus_pending_call_get_completed() to check whether a call has been
 * completed. If it's completed, it will not block.
 *
 * If the call results in an error, the error is set as normal for
 * GError and the function returns #FALSE.
 *
 * Otherwise, the "out" parameters and return value of the
 * method are stored in the provided varargs list.
 * The list should be terminated with DBUS_TYPE_INVALID.
 *
 * This function doesn't affect the reference count of the
 * #DBusPendingCall, the caller of dbus_g_proxy_begin_call() still owns
 * a reference.
 *
 * @param proxy a proxy for a remote interface
 * @param pending the pending call from dbus_g_proxy_begin_call()
 * @param error return location for an error
 * @param first_arg_type type of first "out" argument
 * @returns #FALSE if an error is set */
gboolean
dbus_g_proxy_end_call (DBusGProxy          *proxy,
                      DBusGPendingCall    *pending,
                      GError             **error,
                      int                  first_arg_type,
                      ...)
{
  DBusMessage *message;
  va_list args;
  DBusError derror;
  
  g_return_val_if_fail (DBUS_IS_G_PROXY (proxy), FALSE);
  g_return_val_if_fail (pending != NULL, FALSE);

  dbus_pending_call_block (DBUS_PENDING_CALL_FROM_G_PENDING_CALL (pending));
  message = dbus_pending_call_get_reply (DBUS_PENDING_CALL_FROM_G_PENDING_CALL (pending));

  g_assert (message != NULL);

  dbus_error_init (&derror);

  switch (dbus_message_get_type (message))
    {
    case DBUS_MESSAGE_TYPE_METHOD_RETURN:
      va_start (args, first_arg_type);
      if (!dbus_message_get_args_valist (message, &derror, first_arg_type, args))
        {
          va_end (args);
          goto error;
        }
      va_end (args);

      return TRUE;
      
    case DBUS_MESSAGE_TYPE_ERROR:
      dbus_set_error_from_message (&derror, message);
      goto error;

    default:
      dbus_set_error (&derror, DBUS_ERROR_FAILED,
                      "Reply was neither a method return nor an exception");
      goto error;
    }

 error:
  dbus_set_g_error (error, &derror);
  dbus_error_free (&derror);
  return FALSE;
}

/**
 * Sends a method call message as with dbus_g_proxy_begin_call(), but
 * does not ask for a reply or allow you to receive one.
 *
 * @todo this particular function shouldn't die on out of memory,
 * since you should be able to do a call with large arguments.
 * 
 * @param proxy a proxy for a remote interface
 * @param method the name of the method to invoke
 * @param first_arg_type type of the first argument
 */
void
dbus_g_proxy_call_no_reply (DBusGProxy               *proxy,
                           const char               *method,
                           int                       first_arg_type,
                           ...)
{
  DBusMessage *message;
  va_list args;
  
  g_return_if_fail (DBUS_IS_G_PROXY (proxy));

  message = dbus_message_new_method_call (proxy->service,
                                          proxy->path,
                                          proxy->interface,
                                          method);
  if (message == NULL)
    goto oom;

  dbus_message_set_no_reply (message, TRUE);
  
  va_start (args, first_arg_type);
  if (!dbus_message_append_args_valist (message, first_arg_type,
                                        args))
    goto oom;
  va_end (args);

  if (!dbus_connection_send (proxy->manager->connection,
                             message,
                             NULL))
    goto oom;

  return;
  
 oom:
  g_error ("Out of memory");
}

/**
 * Sends a message to the interface we're proxying for.  Does not
 * block or wait for a reply. The message is only actually written out
 * when you return to the main loop or block in
 * dbus_connection_flush().
 *
 * The message is modified to be addressed to the target interface.
 * That is, a destination service field or whatever is needed will be
 * added to the message. The basic point of this function is to add
 * the necessary header fields, otherwise it's equivalent to
 * dbus_connection_send().
 *
 * This function adds a reference to the message, so the caller
 * still owns its original reference.
 * 
 * @param proxy a proxy for a remote interface
 * @param message the message to address and send
 * @param client_serial return location for message's serial, or #NULL */
void
dbus_g_proxy_send (DBusGProxy          *proxy,
                  DBusMessage         *message,
                  dbus_uint32_t       *client_serial)
{
  g_return_if_fail (DBUS_IS_G_PROXY (proxy));
  
  if (proxy->service)
    {
      if (!dbus_message_set_destination (message, proxy->service))
        g_error ("Out of memory");
    }
  if (proxy->path)
    {
      if (!dbus_message_set_path (message, proxy->path))
        g_error ("Out of memory");
    }
  if (proxy->interface)
    {
      if (!dbus_message_set_interface (message, proxy->interface))
        g_error ("Out of memory");
    }
  
  if (!dbus_connection_send (proxy->manager->connection, message, client_serial))
    g_error ("Out of memory\n");
}

/**
 * Connect a signal handler to a proxy for a remote interface.  When
 * the remote interface emits the specified signal, the proxy will
 * emit a corresponding GLib signal.
 *
 * @todo Right now there's no way to specify the signature to use
 * for invoking the GCallback. Need to either rely on introspection,
 * or require signature here.
 *
 * @param proxy a proxy for a remote interface
 * @param signal_name the DBus signal name to listen for
 * @param handler the handler to connect
 * @param data data to pass to handler
 * @param free_data_func callback function to destroy data
 */
void
dbus_g_proxy_connect_signal (DBusGProxy             *proxy,
                            const char             *signal_name,
                            GCallback               handler,
                            void                   *data,
                            GClosureNotify          free_data_func)
{
  GClosure *closure;
  char *detail;

  g_return_if_fail (DBUS_IS_G_PROXY (proxy));
  g_return_if_fail (signal_name != NULL);
  g_return_if_fail (handler != NULL);
  
  detail = create_signal_detail (proxy->interface, signal_name);
  
  closure = g_cclosure_new (G_CALLBACK (handler), data, free_data_func);
  g_signal_connect_closure_by_id (G_OBJECT (proxy),
                                  signals[RECEIVED],
                                  g_quark_from_string (detail),
                                  closure, FALSE);

  g_free (detail);
}

/**
 * Disconnect all signal handlers from a proxy that match the given
 * criteria.
 *
 * @param proxy a proxy for a remote interface
 * @param signal_name the DBus signal name to disconnect
 * @param handler the handler to disconnect
 * @param data the data that was registered with handler
 */
void
dbus_g_proxy_disconnect_signal (DBusGProxy             *proxy,
                               const char             *signal_name,
                               GCallback               handler,
                               void                   *data)
{
  char *detail;
  GQuark q;
  
  g_return_if_fail (DBUS_IS_G_PROXY (proxy));
  g_return_if_fail (signal_name != NULL);
  g_return_if_fail (handler != NULL);

  detail = create_signal_detail (proxy->interface, signal_name);
  q = g_quark_try_string (detail);
  g_free (detail);

#ifndef G_DISABLE_CHECKS
  if (q == 0)
    {
      g_warning ("%s: No signal handlers for %s found on this DBusGProxy",
                 G_GNUC_FUNCTION, signal_name);
      return;
    }
#endif

  g_signal_handlers_disconnect_matched (G_OBJECT (proxy),
                                        G_SIGNAL_MATCH_DETAIL |
                                        G_SIGNAL_MATCH_FUNC   |
                                        G_SIGNAL_MATCH_DATA,
                                        signals[RECEIVED],
                                        q,
                                        NULL,
                                        G_CALLBACK (handler), data);
}

/** @} End of DBusGLib public */

#ifdef DBUS_BUILD_TESTS

/**
 * @ingroup DBusGLibInternals
 * Unit test for GLib proxy functions
 * @returns #TRUE on success.
 */
gboolean
_dbus_g_proxy_test (void)
{
  
  
  return TRUE;
}

#endif /* DBUS_BUILD_TESTS */