NetworkManager/src/nm-dbus-object.c

/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
/* NetworkManager -- Network link manager
 *
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Copyright 2018 Red Hat, Inc.
 */

#include "nm-default.h"

#include "nm-dbus-object.h"

#include "nm-dbus-manager.h"

/*****************************************************************************/

enum {
	EXPORTED_CHANGED,

	LAST_SIGNAL,
};

static guint signals[LAST_SIGNAL] = { 0 };

G_DEFINE_ABSTRACT_TYPE (NMDBusObject, nm_dbus_object, G_TYPE_OBJECT);

/*****************************************************************************/

#define _NMLOG_DOMAIN      LOGD_CORE
#define _NMLOG(level, ...) __NMLOG_DEFAULT_WITH_ADDR (level, _NMLOG_DOMAIN, "dbus-object", __VA_ARGS__)

#define _NMLOG2_DOMAIN      LOGD_DBUS_PROPS
#define _NMLOG2(level, ...) __NMLOG_DEFAULT_WITH_ADDR (level, _NMLOG2_DOMAIN, "properties-changed", __VA_ARGS__)

/*****************************************************************************/

static void
_emit_exported_changed (NMDBusObject *self)
{
	g_signal_emit (self, signals[EXPORTED_CHANGED], 0);
}

static char *
_create_export_path (NMDBusObjectClass *klass)
{
	nm_assert (NM_IS_DBUS_OBJECT_CLASS (klass));
	nm_assert (klass->export_path.path);

#if NM_MORE_ASSERTS
	{
		const char *p;

		p = strchr (klass->export_path.path, '%');
		if (klass->export_path.int_counter) {
			nm_assert (p);
			nm_assert (p[1] == 'l');
			nm_assert (p[2] == 'l');
			nm_assert (p[3] == 'u');
			nm_assert (p[4] == '\0');
		} else
			nm_assert (!p);
	}
#endif

	if (klass->export_path.int_counter) {
		NM_PRAGMA_WARNING_DISABLE("-Wformat-nonliteral")
		return g_strdup_printf (klass->export_path.path,
		                        ++(*klass->export_path.int_counter));
		NM_PRAGMA_WARNING_REENABLE
	}
	return g_strdup (klass->export_path.path);
}

/**
 * nm_dbus_object_export:
 * @self: an #NMDBusObject
 *
 * Exports @self on all active and future D-Bus connections.
 *
 * The path to export @self on is taken from its #NMObjectClass's %export_path
 * member. If the %export_path contains "%u", then it will be replaced with a
 * monotonically increasing integer ID (with each distinct %export_path having
 * its own counter). Otherwise, %export_path will be used literally (implying
 * that @self must be a singleton).
 *
 * Returns: the path @self was exported under
 */
const char *
nm_dbus_object_export (NMDBusObject *self)
{
	static guint64 id_counter = 0;

	g_return_val_if_fail (NM_IS_DBUS_OBJECT (self), NULL);

	g_return_val_if_fail (!self->internal.path, self->internal.path);

	nm_assert (!self->internal.is_unexporting);

	self->internal.path = _create_export_path (NM_DBUS_OBJECT_GET_CLASS (self));

	self->internal.export_version_id = ++id_counter;

	_LOGT ("export: \"%s\"", self->internal.path);

	_nm_dbus_manager_obj_export (self);

	_emit_exported_changed (self);
	return self->internal.path;
}

/**
 * nm_dbus_object_unexport:
 * @self: an #NMDBusObject
 *
 * Unexports @self on all active D-Bus connections (and prevents it from being
 * auto-exported on future connections).
 */
void
nm_dbus_object_unexport (NMDBusObject *self)
{
	g_return_if_fail (NM_IS_DBUS_OBJECT (self));

	g_return_if_fail (self->internal.path);

	_LOGT ("unexport: \"%s\"", self->internal.path);

	/* note that we emit the signal *before* actually unexporting the object.
	 * The reason is, that listeners want to use this signal to know that
	 * the object goes away, and clear their D-Bus path to this object.
	 *
	 * But this must happen before we actually unregister the object, so
	 * that we first emit a D-Bus signal that other objects no longer
	 * reference this object, before finally unregistering the object itself.
	 *
	 * The inconvenient part is, that at this point nm_dbus_object_get_path()
	 * still returns the path. So, the callee needs to handle that. Possibly
	 * by using "nm_dbus_object_get_path_still_exported()". */
	self->internal.is_unexporting = TRUE;

	_emit_exported_changed (self);

	_nm_dbus_manager_obj_unexport (self);

	g_clear_pointer (&self->internal.path, g_free);
	self->internal.export_version_id = 0;

	self->internal.is_unexporting = FALSE;
}

/*****************************************************************************/

void
_nm_dbus_object_clear_and_unexport (NMDBusObject **location)
{
	NMDBusObject *self;

	g_return_if_fail (location);
	if (!*location)
		return;

	self = g_steal_pointer (location);

	g_return_if_fail (NM_IS_DBUS_OBJECT (self));

	if (self->internal.path)
		nm_dbus_object_unexport (self);

	g_object_unref (self);
}

/*****************************************************************************/

void
nm_dbus_object_emit_signal_variant (NMDBusObject *self,
                                    const NMDBusInterfaceInfoExtended *interface_info,
                                    const GDBusSignalInfo *signal_info,
                                    GVariant *args)
{
	if (!self->internal.path) {
		nm_g_variant_unref_floating (args);
		return;
	}
	_nm_dbus_manager_obj_emit_signal (self, interface_info, signal_info, args);
}

void
nm_dbus_object_emit_signal (NMDBusObject *self,
                            const NMDBusInterfaceInfoExtended *interface_info,
                            const GDBusSignalInfo *signal_info,
                            const char *format,
                            ...)
{
	va_list ap;

	nm_assert (NM_IS_DBUS_OBJECT (self));
	nm_assert (format);

	if (!self->internal.path)
		return;

	va_start (ap, format);
	_nm_dbus_manager_obj_emit_signal (self,
	                                 interface_info,
	                                 signal_info,
	                                 g_variant_new_va (format, NULL, &ap));
	va_end (ap);
}

/*****************************************************************************/

static void
dispatch_properties_changed (GObject *object,
                             guint n_pspecs,
                             GParamSpec **pspecs)
{
	NMDBusObject *self = NM_DBUS_OBJECT (object);

	if (self->internal.path)
		_nm_dbus_manager_obj_notify (self, n_pspecs, (const GParamSpec *const*) pspecs);

	G_OBJECT_CLASS (nm_dbus_object_parent_class)->dispatch_properties_changed (object, n_pspecs, pspecs);
}

/*****************************************************************************/

static void
nm_dbus_object_init (NMDBusObject *self)
{
	c_list_init (&self->internal.objects_lst);
	c_list_init (&self->internal.registration_lst_head);
	self->internal.bus_manager = nm_g_object_ref (nm_dbus_manager_get ());
}

static void
constructed (GObject *object)
{
	NMDBusObjectClass *klass;

	G_OBJECT_CLASS (nm_dbus_object_parent_class)->constructed (object);

	klass = NM_DBUS_OBJECT_GET_CLASS (object);

	if (klass->export_on_construction)
		nm_dbus_object_export ((NMDBusObject *) object);

	/* NMDBusObject types should be very careful when overwriting notify().
	 * It is possible to do, but this is a reminder that it's probably not
	 * a good idea.
	 *
	 * It's not a good idea, because NMDBusObject uses dispatch_properties_changed()
	 * to emit signals about a bunch of property changes. So, we want to make
	 * use of g_object_freeze_notify() / g_object_thaw_notify() to combine multiple
	 * property changes in one signal on D-Bus. Note that notify() is not invoked
	 * while the signal is frozen, that means, whatever you do inside notify()
	 * will not make it into the same batch of PropertiesChanged signal. That is
	 * confusing, and probably not what you want.
	 *
	 * Simple solution: don't overwrite notify(). */
	nm_assert (!G_OBJECT_CLASS (klass)->notify);
}

static void
dispose (GObject *object)
{
	NMDBusObject *self = NM_DBUS_OBJECT (object);

	/* Objects should have already been unexported by their owner, unless
	 * we are quitting, where many objects stick around until exit.
	 */
	if (self->internal.path) {
		if (!nm_dbus_manager_is_stopping (nm_dbus_object_get_manager (self)))
			g_warn_if_reached ();
		nm_dbus_object_unexport (self);
	}

	G_OBJECT_CLASS (nm_dbus_object_parent_class)->dispose (object);

	g_clear_object (&self->internal.bus_manager);
}

static void
nm_dbus_object_class_init (NMDBusObjectClass *klass)
{
	GObjectClass *object_class = G_OBJECT_CLASS (klass);

	object_class->constructed = constructed;
	object_class->dispose = dispose;
	object_class->dispatch_properties_changed = dispatch_properties_changed;

	signals[EXPORTED_CHANGED] =
	    g_signal_new (NM_DBUS_OBJECT_EXPORTED_CHANGED,
	                  G_OBJECT_CLASS_TYPE (object_class),
	                  G_SIGNAL_RUN_FIRST,
	                  0, NULL, NULL,
	                  g_cclosure_marshal_VOID__VOID,
	                  G_TYPE_NONE, 0);
}