Add GTimeZoneMonitor

Monitors /etc/localtime for changes and instructs GTimeZone to drop its
cache.  Also has a signal for interested 3rd parties.

docs/reference/gio/gio-docs.xml

@@ -31,6 +31,7 @@
     <chapter id="file_mon">
         <title>File System Monitoring</title>
         <xi:include href="xml/gfilemonitor.xml"/>
+        <xi:include href="xml/gtimezonemonitor.xml"/>
     </chapter>
     <chapter id="utils">
         <title>File-related Utilities</title>

docs/reference/gio/gio-sections.txt

@@ -3106,3 +3106,16 @@ G_TYPE_TLS_SERVER_CONNECTION
 <SUBSECTION Private>
 g_tls_server_connection_get_type
 </SECTION>
+
+<SECTION>
+<FILE>gtimezonemonitor</FILE>
+<TITLE>GTimeZoneMonitor</TITLE>
+GTimeZoneMonitor
+g_time_zone_monitor_get
+<SUBSECTION Standard>
+G_IS_TIME_ZONE_MONITOR
+G_TIME_ZONE_MONITOR
+G_TYPE_TIME_ZONE_MONITOR
+<SUBSECTION Private>
+g_time_zone_monitor_get_type
+</SECTION>

docs/reference/gio/gio.types

@@ -136,3 +136,4 @@ g_dbus_server_get_type
 g_dbus_auth_observer_get_type
 g_credentials_get_type
 g_unix_credentials_message_get_type
+g_time_zone_monitor_get_type

gio/Makefile.am

@@ -379,6 +379,7 @@ libgio_2_0_la_SOURCES =		\
 	gthemedicon.c 		\
 	gthreadedresolver.c	\
 	gthreadedresolver.h	\
+	gtimezonemonitor.c	\
 	gtlsbackend.c		\
 	gtlscertificate.c	\
 	gtlsclientconnection.c	\
@@ -532,6 +533,7 @@ gio_headers =			\
 	gtcpwrapperconnection.h \
 	gthreadedsocketservice.h\
 	gthemedicon.h 		\
+	gtimezonemonitor.h	\
 	gtlsbackend.h		\
 	gtlscertificate.h	\
 	gtlsclientconnection.h	\

gio/gio.h

@@ -119,6 +119,7 @@
 #include <gio/gtcpwrapperconnection.h>
 #include <gio/gthemedicon.h>
 #include <gio/gthreadedsocketservice.h>
+#include <gio/gtimezonemonitor.h>
 #include <gio/gtlsbackend.h>
 #include <gio/gtlscertificate.h>
 #include <gio/gtlsclientconnection.h>

gio/gtimezonemonitor.c

@@ -0,0 +1,156 @@
+/*
+ * 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);
+}

gio/gtimezonemonitor.h

@@ -0,0 +1,47 @@
+/*
+ * 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>
+ */
+
+#if !defined (__GIO_GIO_H_INSIDE__) && !defined (GIO_COMPILATION)
+#error "Only <gio/gio.h> can be included directly."
+#endif
+
+#ifndef __G_TIME_ZONE_MONITOR_H__
+#define __G_TIME_ZONE_MONITOR_H__
+
+#include "gactiongroup.h"
+
+G_BEGIN_DECLS
+
+#define G_TYPE_TIME_ZONE_MONITOR                          (g_time_zone_monitor_get_type ())
+#define G_TIME_ZONE_MONITOR(inst)                         (G_TYPE_CHECK_INSTANCE_CAST ((inst),                     \
+                                                             G_TYPE_TIME_ZONE_MONITOR, GTimeZoneMonitor))
+#define G_IS_TIME_ZONE_MONITOR(inst)                      (G_TYPE_CHECK_INSTANCE_TYPE ((inst),                     \
+                                                             G_TYPE_TIME_ZONE_MONITOR))
+
+typedef struct _GTimeZoneMonitor                          GTimeZoneMonitor;
+
+GType                   g_time_zone_monitor_get_type                    (void) G_GNUC_CONST;
+
+GTimeZoneMonitor *      g_time_zone_monitor_get                         (void);
+
+G_END_DECLS
+
+#endif /* __G_TIME_ZONE_MONITOR_H__ */

glib/gtimezone.c

@@ -492,6 +492,9 @@ g_time_zone_new_local (void)
  *
  * #GTimeZone does no monitoring of the local timezone on its own, which
  * is why you have to call this function to notify it of the change.
+ *
+ * If you use #GTimeZoneMonitor to watch for changes then this function
+ * will automatically be called for you.
  **/
 void
 g_time_zone_refresh_local (void)