glib/gio/gtimezonemonitor.c

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/*
* Copyright © 2011 Codethink Limited
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2 of the licence or (at
* your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*
* Authors: Ryan Lortie <desrt@desrt.ca>
*/
#include "gtimezonemonitor.h"
#include "gfile.h"
/**
* SECTION:gtimezonemonitor
* @title: GTimeZoneMonitor
* @short_description: Monitor the local timezone
*
* #GTimeZoneMonitor is a utility class to monitor the local timezone for
* changes (ie: in response to the user manually changing the timezone
* to that of a different locale).
*
* You must use this class in order for your program to notice changes
* to the local timezone. It works by monitoring the /etc/localtime
* file. When the timezone is found to have changed,
* g_time_zone_refresh_local() is called and the "changed" signal is
* emitted on the #GTimeZoneMonitor (in that order).
*
* Windows support is not presently working.
**/
/**
* GTimeZoneMonitor:
*
* This is an opaque structure type.
**/
typedef GObjectClass GTimeZoneMonitorClass;
struct _GTimeZoneMonitor
{
GObject parent_instance;
GFileMonitor *monitor;
};
G_DEFINE_TYPE (GTimeZoneMonitor, g_time_zone_monitor, G_TYPE_OBJECT)
static guint g_time_zone_monitor_changed_signal;
static void
etc_localtime_changed (GFileMonitor *monitor,
GFile *file,
GFile *other_file,
GFileMonitorEvent event_type,
gpointer user_data)
{
GTimeZoneMonitor *tzm = user_data;
if (event_type != G_FILE_MONITOR_EVENT_CREATED)
return;
g_time_zone_refresh_local ();
g_signal_emit (tzm, g_time_zone_monitor_changed_signal, 0);
}
static void
g_time_zone_monitor_finalize (GObject *object)
{
g_assert_not_reached ();
}
static void
g_time_zone_monitor_init (GTimeZoneMonitor *tzm)
{
GFile *etc_localtime;
etc_localtime = g_file_new_for_path ("/etc/localtime");
tzm->monitor = g_file_monitor_file (etc_localtime, 0, NULL, NULL);
g_object_unref (etc_localtime);
g_signal_connect (tzm->monitor, "changed",
G_CALLBACK (etc_localtime_changed), tzm);
}
static void
g_time_zone_monitor_class_init (GTimeZoneMonitorClass *class)
{
class->finalize = g_time_zone_monitor_finalize;
/**
* GTimeZoneMonitor::changed
* @monitor: the #GTimeZoneMonitor
*
* Indicates that the local timezone has changed.
*
* The g_time_zone_refresh_local() function is called just before this
* signal is emitted, so any new #GTimeZone or #GDateTime instances
* created from signal handlers will be as per the new timezone.
*
* Note that this signal is not emitted in response to entering or
* exiting daylight savings time within a given timezone. It's only
* for when the user has changed the timezone to that of a different
* location.
**/
g_time_zone_monitor_changed_signal =
g_signal_new ("changed", G_TYPE_TIME_ZONE_MONITOR,
G_SIGNAL_RUN_FIRST, 0, NULL, NULL,
g_cclosure_marshal_VOID__VOID, G_TYPE_NONE, 0);
}
/**
* g_time_zone_monitor_get:
*
* Gets the singleton instance of the #GTimeZoneMonitor class, creating
* it if required.
*
* You should call g_object_unref() on the result when you no longer
* need it. Be aware, though, that this will not destroy the instance,
* so if you connected to the changed signal, you are required to
* disconnect from it for yourself.
*
* There is only one instance of #GTimeZoneMonitor and it dispatches its
* signals via the default #GMainContext. There is no way to create an
* instance that will dispatch signals using a different context.
*
* Returns: a reference to the #GTimeZoneMonitor.
**/
GTimeZoneMonitor *
g_time_zone_monitor_get (void)
{
static gsize instance;
if (g_once_init_enter (&instance))
{
GTimeZoneMonitor *monitor;
monitor = g_object_new (G_TYPE_TIME_ZONE_MONITOR, NULL);
g_once_init_leave (&instance, (gsize) monitor);
}
return g_object_ref ((void *) instance);
}