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class.ilTimeZone.php
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1 <?php
2 /*
3  +-----------------------------------------------------------------------------+
4  | ILIAS open source |
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6  | Copyright (c) 1998-2006 ILIAS open source, University of Cologne |
7  | |
8  | This program is free software; you can redistribute it and/or |
9  | modify it under the terms of the GNU General Public License |
10  | as published by the Free Software Foundation; either version 2 |
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12  | |
13  | This program is distributed in the hope that it will be useful, |
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15  | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
16  | GNU General Public License for more details. |
17  | |
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20  | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
21  +-----------------------------------------------------------------------------+
22 */
23 
41 include_once('Services/Calendar/classes/class.ilTimeZoneException.php');
42 
43 class ilTimeZone
44 {
45  const UTC = 'UTC';
46 
47  public static $instances = array();
48  public static $valid_tz = array();
49 
50  protected static $default_timezone = '';
51  protected static $current_timezone = '';
52  protected static $server_timezone = '';
53 
54  protected $log;
55  protected $timezone = "UTC";
56 
65  private function __construct($a_timezone)
66  {
67  global $ilLog;
68 
69  $this->log = $ilLog;
70 
71  if($a_timezone)
72  {
73  $this->timezone = $a_timezone;
74  }
75  else
76  {
77  $this->timezone = self::_getDefaultTimeZone();
78  }
79 
80  if(!self::$server_timezone)
81  {
82  self::$server_timezone = self::_getDefaultTimeZone();
83  }
84 
85  if(!self::$default_timezone)
86  {
87  self::_getDefaultTimeZone();
88  }
89  }
90 
97  public function getIdentifier()
98  {
99  return $this->timezone;
100  }
101 
111  public static function _getInstance($a_tz = '')
112  {
113  global $ilLog;
114 
115  if(!$a_tz)
116  {
117  $a_tz = self::_getDefaultTimeZone();
118  }
119 
120  if(isset(self::$instances[$a_tz]))
121  {
122  $instance = self::$instances[$a_tz];
123  }
124  else
125  {
126  $instance = self::$instances[$a_tz] = new ilTimeZone($a_tz);
127  }
128 
129  // Validate timezone if it is not validated before
130  if(!array_key_exists($instance->getIdentifier(),self::$valid_tz))
131  {
132  if(!$instance->validateTZ())
133  {
134  throw new ilTimeZoneException('Unsupported timezone given.');
135  }
136  self::$valid_tz[$instance->getIdentifier()] = true;
137  }
138 
139  // now validate timezone setting
140  return $instance;
141  }
142 
148  public function switchTZ()
149  {
150  try
151  {
152  self::_switchTimeZone($this->timezone);
153  return true;
154  }
155  catch(ilTimeZoneException $exc)
156  {
157  // Shouldn't happen since this has been checked during initialisation
158  $this->log->write(__METHOD__.': Unsupported timezone given: Timzone: '.$this->timezone);
159  return false;
160  }
161  }
162 
168  public function restoreTZ()
169  {
170  try
171  {
172  self::_switchTimeZone(self::$default_timezone);
173  return true;
174  }
175  catch(ilTimeZoneException $e)
176  {
177  // Shouldn't happen since this has been checked during initialisation
178  $this->log->write(__METHOD__.': Unsupported timezone given: Timzone: '.$this->timezone);
179  return false;
180  }
181  }
182 
189  public function validateTZ()
190  {
191  // this is done by switching to the current tz
192  if($this->switchTZ() and $this->restoreTZ())
193  {
194  return true;
195  }
196  return false;
197  }
198 
206  protected static function _switchTimeZone($a_timezone)
207  {
208  global $ilLog;
209 
210  if(self::$current_timezone == $a_timezone)
211  {
212  #$ilLog->write(__METHOD__.': Do not switch to active timezone: '.$a_timezone);
213  return true;
214  }
215 
216  // PHP >= 5.2.0
217  if(function_exists('date_default_timezone_set'))
218  {
219  if(!date_default_timezone_set($a_timezone))
220  {
221  $ilLog->write(__METHOD__.': Invalid timezone given. Timezone: '.$a_timezone);
222  throw new ilTimeZoneException('Invalid timezone given');
223  }
224  #$ilLog->write(__METHOD__.': Switched timezone to: '.$a_timezone);
225  self::$current_timezone = $a_timezone;
226  return true;
227  }
228  if(!putenv('TZ='.$a_timezone))
229  {
230  $ilLog->write(__METHOD__.': Cannot set TZ environment variable. Please register TZ in php.ini (safe_mode_allowed_env_vars). Timezone');
231  throw new ilTimeZoneException('Cannot set TZ environment variable.');
232  }
233  self::$current_timezone = $a_timezone;
234  return true;
235  }
236 
245  public static function _setDefaultTimeZone($a_tz)
246  {
247  // Save the server timezone, since there is no way to read later.
248  if(!self::$server_timezone)
249  {
250  self::$server_timezone = self::_getDefaultTimeZone();
251  }
252 
253  self::$default_timezone = $a_tz;
254  }
255 
264  public static function _restoreDefaultTimeZone()
265  {
266  self::$default_timezone = self::$server_timezone;
267  self::_switchTimeZone(self::$default_timezone);
268  }
269 
277  public static function _getDefaultTimeZone()
278  {
279  if(strlen(self::$default_timezone))
280  {
281  return self::$default_timezone;
282  }
283  // PHP >= 5.2.0
284  if(function_exists('date_default_timezone_get') and $tz = date_default_timezone_get())
285  {
286  return self::$default_timezone = $tz;
287  }
288  // PHP ini option (PHP >= 5.1.0)
289  if($tz = ini_get('date.timezone'))
290  {
291  return self::$default_timezone = $tz;
292  }
293  // is $_ENV['PHP_TZ'] set ?
294  if($tz = getenv('PHP_TZ'))
295  {
296  return self::$default_timezone = $tz;
297  }
298  // is $_ENV['TZ'] set ?
299  if($tz = getenv('TZ'))
300  {
301  return self::$default_timezone = $tz;
302  }
303  if(strlen($tz = date('T')))
304  {
305  return self::$default_timezone = $tz;
306  }
307  return self::$default_timezone = self::UTC;
308  }
309 }
310 ?>