examples: add C examples for monitoring whether NM runs

- the first uses dbus-glib and D-Bus "NameOwnerChanged" signal directly
- the second uses GIO's g_bus_watch_name()
- the third uses Qt and QDBusServiceWatcher class

configure.ac

@@ -300,6 +300,9 @@ if (test "${enable_qt}" = "yes"); then
 	fi
 	AC_SUBST(QT_CFLAGS)
 	AC_SUBST(QT_LIBS)
+	# Check for moc-qt4 and if not found then moc
+	QT4_BINDIR=`$PKG_CONFIG Qt --variable bindir`
+	AC_CHECK_PROGS(MOC, [moc-qt4 moc],, [$QT4_BINDIR:$PATH])
 fi
 AM_CONDITIONAL(WITH_QT, test "${enable_qt}" = "yes")
 

examples/C/glib/Makefile.am

@@ -13,7 +13,9 @@ noinst_PROGRAMS = \
 	get-active-connections-dbus-glib \
 	list-connections-dbus-glib \
 	list-connections-libnm-glib \
-	get-ap-info-libnm-glib
+	get-ap-info-libnm-glib \
+	monitor-nm-running-dbus-glib \
+	monitor-nm-running-GDBus
 
 add_connection_dbus_glib_SOURCES = add-connection-dbus-glib.c
 add_connection_dbus_glib_LDADD = \
@@ -54,11 +56,22 @@ get_ap_info_libnm_glib_LDADD = \
 	$(DBUS_LIBS) \
 	$(GLIB_LIBS)
 
+monitor_nm_running_dbus_glib_SOURCES = monitor-nm-running-dbus-glib.c
+monitor_nm_running_dbus_glib_LDADD = \
+	$(DBUS_LIBS) \
+	$(GLIB_LIBS)
+
+monitor_nm_running_GDBus_SOURCES = monitor-nm-running-GDBus.c
+monitor_nm_running_GDBus_LDADD = \
+	$(GIO_LIBS)
+
 EXTRA_DIST = \
 	add-connection-dbus-glib.c \
 	add-connection-libnm-glib.c \
 	get-active-connections-dbus-glib.c \
 	list-connections-dbus-glib.c \
 	list-connections-libnm-glib.c \
-	get-ap-info-libnm-glib.c
+	get-ap-info-libnm-glib.c \
+	monitor-nm-running-dbus-glib.c \
+	monitor-nm-running-GDBus.c
 

examples/C/glib/monitor-nm-running-GDBus.c

@@ -0,0 +1,86 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
+/* vim: set ft=c ts=4 sts=4 sw=4 noexpandtab smartindent: */
+/*
+ * 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.
+ *
+ * (C) Copyright 2012 Red Hat, Inc.
+ */
+
+/*
+ * This example monitors whether NM is running by checking if
+ * "org.freedesktop.NetworkManager" is owned by a process on D-Bus.
+ * It uses g_bus_watch_name().
+ *
+ * See also http://developer.gnome.org/gio/stable/gio-Watching-Bus-Names.html
+ *
+ * Standalone compilation:
+ *   gcc -Wall `pkg-config --libs --cflags glib-2.0 gio-2.0` monitor-nm-running-GDBus.c -o monitor-nm-running-GDBus
+ */
+
+#include <gio/gio.h>
+
+static void
+on_name_appeared (GDBusConnection *connection,
+                  const gchar     *name,
+                  const gchar     *name_owner,
+                  gpointer         user_data)
+{
+	g_print ("Name '%s' on the system bus is owned by %s => NM is running\n",
+	         name, name_owner);
+}
+
+static void
+on_name_vanished (GDBusConnection *connection,
+                  const gchar     *name,
+                  gpointer         user_data)
+{
+	g_print ("Name '%s' does not exist on the system bus => NM is not running\n", name);
+}
+
+
+int
+main (int argc, char *argv[])
+{
+	guint watcher_id;
+	GMainLoop *loop;
+	GBusNameWatcherFlags flags;
+
+	/* Initialize GType system */
+	g_type_init ();
+
+	g_print ("Monitor 'org.freedesktop.NetworkManager' D-Bus name\n");
+	g_print ("===================================================\n");
+
+	flags = G_BUS_NAME_WATCHER_FLAGS_NONE;
+
+	/* Start to watch "org.freedesktop.NetworkManager" bus name */
+	watcher_id = g_bus_watch_name (G_BUS_TYPE_SYSTEM,
+	                               "org.freedesktop.NetworkManager",
+	                               flags,
+	                               on_name_appeared,
+	                               on_name_vanished,
+	                               NULL,
+	                               NULL);
+
+	/* Run main loop */
+	loop = g_main_loop_new (NULL, FALSE);
+	g_main_loop_run (loop);
+
+	/* Stop watching the name */
+	g_bus_unwatch_name (watcher_id);
+
+	return 0;
+}
+

examples/C/glib/monitor-nm-running-dbus-glib.c

@@ -0,0 +1,125 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
+/* vim: set ft=c ts=4 sts=4 sw=4 noexpandtab smartindent: */
+/*
+ * 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.
+ *
+ * (C) Copyright 2012 Red Hat, Inc.
+ */
+
+/*
+ * This example monitors whether NM is running by checking D-Bus
+ * NameOwnerChanged signal.
+ * It uses dbus-glib library.
+ *
+ * Standalone compilation:
+ *   gcc -Wall `pkg-config --libs --cflags glib-2.0 dbus-glib-1` monitor-nm-running.c -o monitor-nm-running
+ */
+
+#include <glib.h>
+#include <dbus/dbus-glib.h>
+#include <dbus/dbus-glib-bindings.h>
+#include <string.h>
+
+#define NM_DBUS_SERVICE "org.freedesktop.NetworkManager"
+
+static void
+proxy_name_owner_changed (DBusGProxy *proxy,
+                          const char *name,
+                          const char *old_owner,
+                          const char *new_owner,
+                          gpointer user_data)
+{
+	gboolean *nm_running = (gboolean *) user_data;
+	gboolean old_good = (old_owner && strlen (old_owner));
+	gboolean new_good = (new_owner && strlen (new_owner));
+	gboolean new_running = FALSE;
+
+	/* We are only interested in NetworkManager */
+	if (!name || strcmp (name, NM_DBUS_SERVICE) != 0)
+		return;
+
+	if (!old_good && new_good)
+		new_running = TRUE;
+	else if (old_good && !new_good)
+		new_running = FALSE;
+
+	*nm_running = new_running;
+
+	g_print ("name: '%s', old_owner: '%s', new_owner: '%s'", name, old_owner, new_owner);
+	g_print (" => NM is %s\n", *nm_running ? "running" : "not running");
+}
+
+
+int
+main (int argc, char *argv[])
+{
+	DBusGConnection *bus;
+	DBusGProxy *bus_proxy;
+	GMainLoop *loop = NULL;
+	GError *err = NULL;
+	gboolean nm_running;
+
+	/* Initialize GType system */
+	g_type_init ();
+
+	g_print ("Monitor 'org.freedesktop.NetworkManager' D-Bus name\n");
+	g_print ("===================================================\n");
+
+	/* Get system bus */
+	bus = dbus_g_bus_get (DBUS_BUS_SYSTEM, NULL);
+
+	/* Create a D-Bus proxy to D-Bus daemon */
+	bus_proxy = dbus_g_proxy_new_for_name (bus,
+	                                       "org.freedesktop.DBus",
+	                                       "/org/freedesktop/DBus",
+	                                       "org.freedesktop.DBus");
+
+	if (!bus_proxy) {
+		g_message ("Error: Couldn't create D-Bus object proxy for org.freedesktop.DBus.");
+		dbus_g_connection_unref (bus);
+		return -1;
+	}
+
+	/* Call NameHasOwner method to find out if NM is running. When NM runs it claims
+	 * 'org.freedesktop.NetworkManager' service name on D-Bus */
+	if (!org_freedesktop_DBus_name_has_owner (bus_proxy, NM_DBUS_SERVICE, &nm_running, &err)) {
+		g_message ("Error: NameHasOwner request failed: %s",
+		                 (err && err->message) ? err->message : "(unknown)");
+		g_clear_error (&err);
+		g_object_unref (bus_proxy);
+		dbus_g_connection_unref (bus);
+		return -1;
+	}
+	g_print ("NM is %s\n", nm_running ? "running" : "not running");
+
+
+	/* Connect to NameOwnerChanged signal to monitor NM running state */
+	dbus_g_proxy_add_signal (bus_proxy, "NameOwnerChanged",
+	                         G_TYPE_STRING, G_TYPE_STRING, G_TYPE_STRING,
+	                         G_TYPE_INVALID);
+	dbus_g_proxy_connect_signal (bus_proxy,
+	                             "NameOwnerChanged",
+	                             G_CALLBACK (proxy_name_owner_changed),
+	                             &nm_running, NULL);
+
+	loop = g_main_loop_new (NULL, FALSE);  /* Create main loop */
+	g_main_loop_run (loop);                /* Run main loop */
+
+	g_object_unref (bus_proxy);
+	dbus_g_connection_unref (bus);
+
+	return 0;
+}
+

examples/C/qt/Makefile.am

@@ -8,7 +8,8 @@ AM_CPPFLAGS = \
 noinst_PROGRAMS = \
 	add-connection-wired \
 	list-connections \
-	change-ipv4-addresses
+	change-ipv4-addresses \
+	monitor-nm-running
 
 add_connection_wired_SOURCES = add-connection-wired.cpp
 add_connection_wired_LDADD = \
@@ -25,8 +26,22 @@ change_ipv4_addresses_LDADD = \
 	$(DBUS_LIBS) \
 	$(QT_LIBS)
 
+monitor_nm_running_SOURCES = monitor-nm-running.cpp
+monitor_nm_running_LDADD = \
+	$(DBUS_LIBS) \
+	$(QT_LIBS)
+
+monitor-nm-running.moc: monitor-nm-running.cpp
+	$(AM_V_GEN) $(MOC) -i $< -o $@
+
+BUILT_SOURCES = \
+	monitor-nm-running.moc
+
 EXTRA_DIST = \
 	add-connection-wired.cpp \
 	list-connections.cpp \
-	change-ipv4-addresses.cpp
+	change-ipv4-addresses.cpp \
+	monitor-nm-running.cpp
+
+CLEANFILES = $(BUILT_SOURCES)
 

examples/C/qt/monitor-nm-running.cpp

@@ -0,0 +1,89 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
+/* vim: set ft=c ts=4 sts=4 sw=4 expandtab smartindent: */
+/*
+ * 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.
+ *
+ * (C) Copyright 2012 Red Hat, Inc.
+ */
+
+/*
+ * This example monitors whether NM is running by checking if
+ * "org.freedesktop.NetworkManager" is owned by a process on D-Bus.
+ * It uses QDBusServiceWatcher class.
+ *
+ * Standalone compilation:
+ *   moc-qt4 monitor-nm-running.cpp -o monitor-nm-running.moc
+ *   g++ -Wall `pkg-config --libs --cflags QtCore QtDBus` monitor-nm-running.cpp -o monitor-nm-running
+ *
+ * You don't need to have NetworkManager devel package installed.
+ */
+
+#include <iostream>
+#include <QObject>
+#include <QCoreApplication>
+#include <QtDBus/QDBusServiceWatcher>
+#include <QtDBus/QDBusConnection>
+#include <QtCore/QDebug>
+
+const QString NM_DBUS_SERVICE = "org.freedesktop.NetworkManager";
+
+// Define a class with slots
+class NMWatcher: public QObject {
+    Q_OBJECT;
+
+    public slots:
+        void serviceRegistered(const QString& name);
+        void serviceUnregistered(const QString& name);
+};
+
+
+void NMWatcher::serviceRegistered(const QString& name)
+{
+    std::cout << "Name '" << name.toStdString() << "' registered"
+              << " => NM is running" << std::endl;
+}
+
+void NMWatcher::serviceUnregistered(const QString& name)
+{
+    std::cout << "Name '" << name.toStdString() << "' unregistered"
+              << " => NM is not running" << std::endl;
+}
+
+int main(int argc, char *argv[])
+{
+    QCoreApplication app (argc, argv);
+
+    qDebug() << "Monitor 'org.freedesktop.NetworkManager' D-Bus name";
+    qDebug() << "===================================================";
+
+    NMWatcher nm_watcher;
+
+    // Watch all changes of D-Bus NM_DBUS_SERVICE name
+    QDBusServiceWatcher *watcher = new QDBusServiceWatcher(NM_DBUS_SERVICE,
+                                                           QDBusConnection::systemBus());
+
+    QObject::connect(watcher, SIGNAL(serviceRegistered(const QString&)),
+                     &nm_watcher, SLOT(serviceRegistered(const QString&)));
+
+    QObject::connect(watcher, SIGNAL(serviceUnregistered(const QString&)),
+                     &nm_watcher, SLOT(serviceUnregistered(const QString&)));
+
+    app.exec();
+
+    delete watcher;
+    return 0;
+}
+
+#include "monitor-nm-running.moc"