About creating service on dbus

xor exor makkalot at gmail.com
Thu Jul 29 08:10:27 PDT 2010


Hi i'm trying to code a service that will be on dbus session bus.

The xml definiton :

<?xml version="1.0" encoding="UTF-8"?>

<node name="/net/skynet/Echo">
    <interface name="net.skynet.Echo">
        <annotation name="org.freedesktop.DBus.GLib.CSymbol"
value="server"/>
        <method name="EchoString">
            <arg type="s" name="original" direction="in" />
            <arg type="s" name="echo" direction="out" />
        </method>
        <!-- Add more methods/signals if you want -->
    </interface>
</node>


-----------------------------------------------------------------------------------------------------------

The generated .h file :

/* Generated by dbus-binding-tool; do not edit! */


#ifndef __dbus_glib_marshal_server_object_MARSHAL_H__
#define __dbus_glib_marshal_server_object_MARSHAL_H__

#include    <glib-object.h>

G_BEGIN_DECLS

#ifdef G_ENABLE_DEBUG
#define g_marshal_value_peek_boolean(v)  g_value_get_boolean (v)
#define g_marshal_value_peek_char(v)     g_value_get_char (v)
#define g_marshal_value_peek_uchar(v)    g_value_get_uchar (v)
#define g_marshal_value_peek_int(v)      g_value_get_int (v)
#define g_marshal_value_peek_uint(v)     g_value_get_uint (v)
#define g_marshal_value_peek_long(v)     g_value_get_long (v)
#define g_marshal_value_peek_ulong(v)    g_value_get_ulong (v)
#define g_marshal_value_peek_int64(v)    g_value_get_int64 (v)
#define g_marshal_value_peek_uint64(v)   g_value_get_uint64 (v)
#define g_marshal_value_peek_enum(v)     g_value_get_enum (v)
#define g_marshal_value_peek_flags(v)    g_value_get_flags (v)
#define g_marshal_value_peek_float(v)    g_value_get_float (v)
#define g_marshal_value_peek_double(v)   g_value_get_double (v)
#define g_marshal_value_peek_string(v)   (char*) g_value_get_string (v)
#define g_marshal_value_peek_param(v)    g_value_get_param (v)
#define g_marshal_value_peek_boxed(v)    g_value_get_boxed (v)
#define g_marshal_value_peek_pointer(v)  g_value_get_pointer (v)
#define g_marshal_value_peek_object(v)   g_value_get_object (v)
#else /* !G_ENABLE_DEBUG */
/* WARNING: This code accesses GValues directly, which is UNSUPPORTED API.
 *          Do not access GValues directly in your code. Instead, use the
 *          g_value_get_*() functions
 */
#define g_marshal_value_peek_boolean(v)  (v)->data[0].v_int
#define g_marshal_value_peek_char(v)     (v)->data[0].v_int
#define g_marshal_value_peek_uchar(v)    (v)->data[0].v_uint
#define g_marshal_value_peek_int(v)      (v)->data[0].v_int
#define g_marshal_value_peek_uint(v)     (v)->data[0].v_uint
#define g_marshal_value_peek_long(v)     (v)->data[0].v_long
#define g_marshal_value_peek_ulong(v)    (v)->data[0].v_ulong
#define g_marshal_value_peek_int64(v)    (v)->data[0].v_int64
#define g_marshal_value_peek_uint64(v)   (v)->data[0].v_uint64
#define g_marshal_value_peek_enum(v)     (v)->data[0].v_long
#define g_marshal_value_peek_flags(v)    (v)->data[0].v_ulong
#define g_marshal_value_peek_float(v)    (v)->data[0].v_float
#define g_marshal_value_peek_double(v)   (v)->data[0].v_double
#define g_marshal_value_peek_string(v)   (v)->data[0].v_pointer
#define g_marshal_value_peek_param(v)    (v)->data[0].v_pointer
#define g_marshal_value_peek_boxed(v)    (v)->data[0].v_pointer
#define g_marshal_value_peek_pointer(v)  (v)->data[0].v_pointer
#define g_marshal_value_peek_object(v)   (v)->data[0].v_pointer
#endif /* !G_ENABLE_DEBUG */


/* BOOLEAN:STRING,POINTER,POINTER */
extern void dbus_glib_marshal_server_object_BOOLEAN__STRING_POINTER_POINTER
(GClosure     *closure,

GValue       *return_value,

guint         n_param_values,

const GValue *param_values,

gpointer      invocation_hint,

gpointer      marshal_data);
void
dbus_glib_marshal_server_object_BOOLEAN__STRING_POINTER_POINTER
(GClosure     *closure,

GValue       *return_value G_GNUC_UNUSED,

guint         n_param_values,
                                                                 const
GValue *param_values,

gpointer      invocation_hint G_GNUC_UNUSED,

gpointer      marshal_data)
{
  typedef gboolean (*GMarshalFunc_BOOLEAN__STRING_POINTER_POINTER)
(gpointer     data1,

gpointer     arg_1,

gpointer     arg_2,

gpointer     arg_3,

gpointer     data2);
  register GMarshalFunc_BOOLEAN__STRING_POINTER_POINTER callback;
  register GCClosure *cc = (GCClosure*) closure;
  register gpointer data1, data2;
  gboolean v_return;

  g_return_if_fail (return_value != NULL);
  g_return_if_fail (n_param_values == 4);

  if (G_CCLOSURE_SWAP_DATA (closure))
    {
      data1 = closure->data;
      data2 = g_value_peek_pointer (param_values + 0);
    }
  else
    {
      data1 = g_value_peek_pointer (param_values + 0);
      data2 = closure->data;
    }
  callback = (GMarshalFunc_BOOLEAN__STRING_POINTER_POINTER) (marshal_data ?
marshal_data : cc->callback);

  v_return = callback (data1,
                       g_marshal_value_peek_string (param_values + 1),
                       g_marshal_value_peek_pointer (param_values + 2),
                       g_marshal_value_peek_pointer (param_values + 3),
                       data2);

  g_value_set_boolean (return_value, v_return);
}

G_END_DECLS

#endif /* __dbus_glib_marshal_server_object_MARSHAL_H__ */

#include <dbus/dbus-glib.h>
static const DBusGMethodInfo dbus_glib_server_object_methods[] = {
  { (GCallback) server_echo_string,
dbus_glib_marshal_server_object_BOOLEAN__STRING_POINTER_POINTER, 0 },
};

const DBusGObjectInfo dbus_glib_server_object_object_info = {
  0,
  dbus_glib_server_object_methods,
  1,
"net.skynet.Echo\0EchoString\0S\0original\0I\0s\0echo\0O\0F\0N\0s\0\0\0",
"\0",
"\0"
};

----------------------------------------------------------------------------------------------------------------------------------------

And the service part :

#include <dbus/dbus-glib-bindings.h>

//Here you can define you own objects !
typedef struct GpkDbus_{
    guint dummy;
}GpkDbus;

extern gboolean server_echo_string (GpkDbus *server, gchar *original, gchar
**echo, GError **error);

#include "echo_server_bindings.h"

#define ECHO_SERVICE_NAME "net.skynet.Echo"
#define ECHO_OBJECT_NAME "/net/skynet/Echo"
#define ECHO_INTERFACE_NAME "net.skynet.Echo"


static GMainLoop *loop = NULL;


/**
 * echo_service_object_register:
 * @connection: What we want to register to
 * @object: The GObject we want to register
 *
 * Return value: success
 **/
static gboolean
echo_service_object_register (DBusGConnection *connection, GObject *object)
{
    DBusGProxy *bus_proxy = NULL;
    GError *error = NULL;
    guint request_name_result;
    gboolean ret;

    /* connect to the bus */
    bus_proxy = dbus_g_proxy_new_for_name (connection, DBUS_SERVICE_DBUS,
                           DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS);

    /* get our name */
    ret = dbus_g_proxy_call (bus_proxy, "RequestName", &error,
                 G_TYPE_STRING, ECHO_SERVICE_NAME,
                 G_TYPE_UINT, DBUS_NAME_FLAG_ALLOW_REPLACEMENT |
                          DBUS_NAME_FLAG_REPLACE_EXISTING |
                          DBUS_NAME_FLAG_DO_NOT_QUEUE,
                 G_TYPE_INVALID,
                 G_TYPE_UINT, &request_name_result,
                 G_TYPE_INVALID);
    if (!ret) {
        /* abort as the DBUS method failed */
        g_warning ("RequestName failed: %s", error->message);
        g_error_free (error);
        return FALSE;
    }

    /* free the bus_proxy */
    g_object_unref (G_OBJECT (bus_proxy));

    /* already running */
    if (request_name_result != DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER)
        return FALSE;

    // ERRROR HERE ! ...
    dbus_g_object_type_install_info (G_TYPE_FROM_CLASS (object),
&dbus_glib_server_object_object_info);
    //dbus_g_error_domain_register (GPK_DBUS_ERROR, NULL,
GPK_DBUS_TYPE_ERROR);
    dbus_g_connection_register_g_object (connection, ECHO_OBJECT_NAME,
object);

    return TRUE;
}



/**
 * main:
 **/
int
main (int argc, char *argv[])
{
    GpkDbus *dbus = NULL;
    GError *error = NULL;
    gboolean ret;
    guint retval = 0;
    DBusGConnection *connection;


    if (! g_thread_supported ())
        g_thread_init (NULL);
    dbus_g_thread_init ();
    g_type_init ();


    loop = g_main_loop_new (NULL, FALSE);

    /* get the bus */
    connection = dbus_g_bus_get (DBUS_BUS_SESSION, &error);
    if (error) {
        g_warning ("%s", error->message);
        g_error_free (error);
        retval = 1;
        goto out;
    }

    /* try to register */
    ret = echo_service_object_register (connection, G_OBJECT (dbus));
    if (!ret) {
        g_warning ("failed to replace running instance.");
        retval = 1;
        goto out;
    }

    /* wait */
    g_main_loop_run (loop);
out:
    g_main_loop_unref (loop);
    g_object_unref (dbus);
    return retval;
}


gboolean
server_echo_string (GpkDbus *server, gchar *original, gchar **echo, GError
**error)
{
    *echo = g_strdup(original);

    if (0)
    {
        /* We have an error, set the gerror */
        g_set_error (error, g_quark_from_static_string ("echo"),
                    0xdeadbeef,
                    "Some random problem occured, you're screwed");
        return FALSE;
    }

    return TRUE;
}


---------------------------------------------------------------------------------------------------------


Here are the parts that are confusing :

What should be the 1st parameter of dbus_g_object_type_install_info
function ?



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