lib/setuplib.php

   1 <?php
   2
   3 // This file is part of Moodle - http://moodle.org/
   4 //
   5 // Moodle is free software: you can redistribute it and/or modify
   6 // it under the terms of the GNU General Public License as published by
   7 // the Free Software Foundation, either version 3 of the License, or
   8 // (at your option) any later version.
   9 //
  10 // Moodle is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU General Public License
  16 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  17
  18
  19 /**
  20  * These functions are required very early in the Moodle
  21  * setup process, before any of the main libraries are
  22  * loaded.
  23  *
  24  * @package    core
  25  * @subpackage lib
  26  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
  27  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  28  */
  29
  30 defined('MOODLE_INTERNAL') || die();
  31
  32 /// Debug levels ///
  33 /** no warnings at all */
  34 define('DEBUG_NONE', 0);
  35 /** E_ERROR | E_PARSE */
  36 define('DEBUG_MINIMAL', 5);
  37 /** E_ERROR | E_PARSE | E_WARNING | E_NOTICE */
  38 define('DEBUG_NORMAL', 15);
  39 /** E_ALL without E_STRICT for now, do show recoverable fatal errors */
  40 define('DEBUG_ALL', 6143);
  41 /** DEBUG_ALL with extra Moodle debug messages - (DEBUG_ALL | 32768) */
  42 define('DEBUG_DEVELOPER', 38911);
  43
  44 /** Remove any memory limits */
  45 define('MEMORY_UNLIMITED', -1);
  46 /** Standard memory limit for given platform */
  47 define('MEMORY_STANDARD', -2);
  48 /**
  49  * Large memory limit for given platform - used in cron, upgrade, and other places that need a lot of memory.
  50  * Can be overridden with $CFG->extramemorylimit setting.
  51  */
  52 define('MEMORY_EXTRA', -3);
  53 /** Extremely large memory limit - not recommended for standard scripts */
  54 define('MEMORY_HUGE', -4);
  55
  56 /**
  57  * Simple class. It is usually used instead of stdClass because it looks
  58  * more familiar to Java developers ;-) Do not use for type checking of
  59  * function parameters. Please use stdClass instead.
  60  *
  61  * @package    core
  62  * @subpackage lib
  63  * @copyright  2009 Petr Skoda  {@link http://skodak.org}
  64  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  65  * @deprecated since 2.0
  66  */
  67 class object extends stdClass {};
  68
  69 /**
  70  * Base Moodle Exception class
  71  *
  72  * Although this class is defined here, you cannot throw a moodle_exception until
  73  * after moodlelib.php has been included (which will happen very soon).
  74  *
  75  * @package    core
  76  * @subpackage lib
  77  * @copyright  2008 Petr Skoda  {@link http://skodak.org}
  78  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  79  */
  80 class moodle_exception extends Exception {
  81     public $errorcode;
  82     public $module;
  83     public $a;
  84     public $link;
  85     public $debuginfo;
  86
  87     /**
  88      * Constructor
  89      * @param string $errorcode The name of the string from error.php to print
  90      * @param string $module name of module
  91      * @param string $link The url where the user will be prompted to continue. If no url is provided the user will be directed to the site index page.
  92      * @param object $a Extra words and phrases that might be required in the error string
  93      * @param string $debuginfo optional debugging information
  94      */
  95     function __construct($errorcode, $module='', $link='', $a=NULL, $debuginfo=null) {
  96         if (empty($module) || $module == 'moodle' || $module == 'core') {
  97             $module = 'error';
  98         }
  99
 100         $this->errorcode = $errorcode;
 101         $this->module    = $module;
 102         $this->link      = $link;
 103         $this->a         = $a;
 104         $this->debuginfo = $debuginfo;
 105
 106         if (get_string_manager()->string_exists($errorcode, $module)) {
 107             $message = get_string($errorcode, $module, $a);
 108         } else {
 109             $message = $module . '/' . $errorcode;
 110         }
 111
 112         parent::__construct($message, 0);
 113     }
 114 }
 115
 116 /**
 117  * Course/activity access exception.
 118  *
 119  * This exception is thrown from require_login()
 120  *
 121  * @package    core
 122  * @subpackage lib
 123  * @copyright  2010 Petr Skoda  {@link http://skodak.org}
 124  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 125  */
 126 class require_login_exception extends moodle_exception {
 127     function __construct($debuginfo) {
 128         parent::__construct('requireloginerror', 'error', '', NULL, $debuginfo);
 129     }
 130 }
 131
 132 /**
 133  * Web service parameter exception class
 134  *
 135  * This exception must be thrown to the web service client when a web service parameter is invalid
 136  * The error string is gotten from webservice.php
 137  */
 138 class webservice_parameter_exception extends moodle_exception {
 139     /**
 140      * Constructor
 141      * @param string $errorcode The name of the string from webservice.php to print
 142      * @param string $a The name of the parameter
 143      */
 144     function __construct($errorcode=null, $a = '') {
 145         parent::__construct($errorcode, 'webservice', '', $a, null);
 146     }
 147 }
 148
 149 /**
 150  * Exceptions indicating user does not have permissions to do something
 151  * and the execution can not continue.
 152  *
 153  * @package    core
 154  * @subpackage lib
 155  * @copyright  2009 Petr Skoda  {@link http://skodak.org}
 156  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 157  */
 158 class required_capability_exception extends moodle_exception {
 159     function __construct($context, $capability, $errormessage, $stringfile) {
 160         $capabilityname = get_capability_string($capability);
 161         if ($context->contextlevel == CONTEXT_MODULE and preg_match('/:view$/', $capability)) {
 162             // we can not go to mod/xx/view.php because we most probably do not have cap to view it, let's go to course instead
 163             $paranetcontext = get_context_instance_by_id(get_parent_contextid($context));
 164             $link = get_context_url($paranetcontext);
 165         } else {
 166             $link = get_context_url($context);
 167         }
 168         parent::__construct($errormessage, $stringfile, $link, $capabilityname);
 169     }
 170 }
 171
 172 /**
 173  * Exception indicating programming error, must be fixed by a programer. For example
 174  * a core API might throw this type of exception if a plugin calls it incorrectly.
 175  *
 176  * @package    core
 177  * @subpackage lib
 178  * @copyright  2008 Petr Skoda  {@link http://skodak.org}
 179  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 180  */
 181 class coding_exception extends moodle_exception {
 182     /**
 183      * Constructor
 184      * @param string $hint short description of problem
 185      * @param string $debuginfo detailed information how to fix problem
 186      */
 187     function __construct($hint, $debuginfo=null) {
 188         parent::__construct('codingerror', 'debug', '', $hint, $debuginfo);
 189     }
 190 }
 191
 192 /**
 193  * Exception indicating malformed parameter problem.
 194  * This exception is not supposed to be thrown when processing
 195  * user submitted data in forms. It is more suitable
 196  * for WS and other low level stuff.
 197  *
 198  * @package    core
 199  * @subpackage lib
 200  * @copyright  2009 Petr Skoda  {@link http://skodak.org}
 201  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 202  */
 203 class invalid_parameter_exception extends moodle_exception {
 204     /**
 205      * Constructor
 206      * @param string $debuginfo some detailed information
 207      */
 208     function __construct($debuginfo=null) {
 209         parent::__construct('invalidparameter', 'debug', '', null, $debuginfo);
 210     }
 211 }
 212
 213 /**
 214  * Exception indicating malformed response problem.
 215  * This exception is not supposed to be thrown when processing
 216  * user submitted data in forms. It is more suitable
 217  * for WS and other low level stuff.
 218  */
 219 class invalid_response_exception extends moodle_exception {
 220     /**
 221      * Constructor
 222      * @param string $debuginfo some detailed information
 223      */
 224     function __construct($debuginfo=null) {
 225         parent::__construct('invalidresponse', 'debug', '', null, $debuginfo);
 226     }
 227 }
 228
 229 /**
 230  * An exception that indicates something really weird happened. For example,
 231  * if you do switch ($context->contextlevel), and have one case for each
 232  * CONTEXT_... constant. You might throw an invalid_state_exception in the
 233  * default case, to just in case something really weird is going on, and
 234  * $context->contextlevel is invalid - rather than ignoring this possibility.
 235  *
 236  * @package    core
 237  * @subpackage lib
 238  * @copyright  2009 onwards Martin Dougiamas  {@link http://moodle.com}
 239  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 240  */
 241 class invalid_state_exception extends moodle_exception {
 242     /**
 243      * Constructor
 244      * @param string $hint short description of problem
 245      * @param string $debuginfo optional more detailed information
 246      */
 247     function __construct($hint, $debuginfo=null) {
 248         parent::__construct('invalidstatedetected', 'debug', '', $hint, $debuginfo);
 249     }
 250 }
 251
 252 /**
 253  * An exception that indicates incorrect permissions in $CFG->dataroot
 254  *
 255  * @package    core
 256  * @subpackage lib
 257  * @copyright  2010 Petr Skoda {@link http://skodak.org}
 258  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 259  */
 260 class invalid_dataroot_permissions extends moodle_exception {
 261     /**
 262      * Constructor
 263      * @param string $debuginfo optional more detailed information
 264      */
 265     function __construct($debuginfo = NULL) {
 266         parent::__construct('invaliddatarootpermissions', 'error', '', NULL, $debuginfo);
 267     }
 268 }
 269
 270 /**
 271  * An exception that indicates that file can not be served
 272  *
 273  * @package    core
 274  * @subpackage lib
 275  * @copyright  2010 Petr Skoda {@link http://skodak.org}
 276  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 277  */
 278 class file_serving_exception extends moodle_exception {
 279     /**
 280      * Constructor
 281      * @param string $debuginfo optional more detailed information
 282      */
 283     function __construct($debuginfo = NULL) {
 284         parent::__construct('cannotservefile', 'error', '', NULL, $debuginfo);
 285     }
 286 }
 287
 288 /**
 289  * Default exception handler, uncaught exceptions are equivalent to error() in 1.9 and earlier
 290  *
 291  * @param Exception $ex
 292  * @return void -does not return. Terminates execution!
 293  */
 294 function default_exception_handler($ex) {
 295     global $CFG, $DB, $OUTPUT, $USER, $FULLME, $SESSION;
 296
 297     // detect active db transactions, rollback and log as error
 298     abort_all_db_transactions();
 299
 300     if (($ex instanceof required_capability_exception) && !CLI_SCRIPT && !AJAX_SCRIPT && !empty($CFG->autologinguests) && !empty($USER->autologinguest)) {
 301         $SESSION->wantsurl = $FULLME;
 302         redirect(get_login_url());
 303     }
 304
 305     $info = get_exception_info($ex);
 306
 307     if (debugging('', DEBUG_MINIMAL)) {
 308         $logerrmsg = "Default exception handler: ".$info->message.' Debug: '.$info->debuginfo."\n".format_backtrace($info->backtrace, true);
 309         error_log($logerrmsg);
 310     }
 311
 312     if (is_early_init($info->backtrace)) {
 313         echo bootstrap_renderer::early_error($info->message, $info->moreinfourl, $info->link, $info->backtrace, $info->debuginfo);
 314     } else {
 315         try {
 316             if ($DB) {
 317                 // If you enable db debugging and exception is thrown, the print footer prints a lot of rubbish
 318                 $DB->set_debug(0);
 319             }
 320             echo $OUTPUT->fatal_error($info->message, $info->moreinfourl, $info->link, $info->backtrace, $info->debuginfo);
 321         } catch (Exception $out_ex) {
 322             // default exception handler MUST not throw any exceptions!!
 323             // the problem here is we do not know if page already started or not, we only know that somebody messed up in outputlib or theme
 324             // so we just print at least something instead of "Exception thrown without a stack frame in Unknown on line 0":-(
 325             if (CLI_SCRIPT or AJAX_SCRIPT) {
 326                 // just ignore the error and send something back using the safest method
 327                 echo bootstrap_renderer::early_error($info->message, $info->moreinfourl, $info->link, $info->backtrace, $info->debuginfo);
 328             } else {
 329                 echo bootstrap_renderer::early_error_content($info->message, $info->moreinfourl, $info->link, $info->backtrace, $info->debuginfo);
 330                 $outinfo = get_exception_info($out_ex);
 331                 echo bootstrap_renderer::early_error_content($outinfo->message, $outinfo->moreinfourl, $outinfo->link, $outinfo->backtrace, $outinfo->debuginfo);
 332             }
 333         }
 334     }
 335
 336     exit(1); // General error code
 337 }
 338
 339 /**
 340  * Default error handler, prevents some white screens.
 341  * @param int $errno
 342  * @param string $errstr
 343  * @param string $errfile
 344  * @param int $errline
 345  * @param array $errcontext
 346  * @return bool false means use default error handler
 347  */
 348 function default_error_handler($errno, $errstr, $errfile, $errline, $errcontext) {
 349     if ($errno == 4096) {
 350         //fatal catchable error
 351         throw new coding_exception('PHP catchable fatal error', $errstr);
 352     }
 353     return false;
 354 }
 355
 356 /**
 357  * Unconditionally abort all database transactions, this function
 358  * should be called from exception handlers only.
 359  * @return void
 360  */
 361 function abort_all_db_transactions() {
 362     global $CFG, $DB, $SCRIPT;
 363
 364     // default exception handler MUST not throw any exceptions!!
 365
 366     if ($DB && $DB->is_transaction_started()) {
 367         error_log('Database transaction aborted automatically in ' . $CFG->dirroot . $SCRIPT);
 368         // note: transaction blocks should never change current $_SESSION
 369         $DB->force_transaction_rollback();
 370     }
 371 }
 372
 373 /**
 374  * This function encapsulates the tests for whether an exception was thrown in
 375  * early init -- either during setup.php or during init of $OUTPUT.
 376  *
 377  * If another exception is thrown then, and if we do not take special measures,
 378  * we would just get a very cryptic message "Exception thrown without a stack
 379  * frame in Unknown on line 0". That makes debugging very hard, so we do take
 380  * special measures in default_exception_handler, with the help of this function.
 381  *
 382  * @param array $backtrace the stack trace to analyse.
 383  * @return boolean whether the stack trace is somewhere in output initialisation.
 384  */
 385 function is_early_init($backtrace) {
 386     $dangerouscode = array(
 387         array('function' => 'header', 'type' => '->'),
 388         array('class' => 'bootstrap_renderer'),
 389         array('file' => dirname(__FILE__).'/setup.php'),
 390     );
 391     foreach ($backtrace as $stackframe) {
 392         foreach ($dangerouscode as $pattern) {
 393             $matches = true;
 394             foreach ($pattern as $property => $value) {
 395                 if (!isset($stackframe[$property]) || $stackframe[$property] != $value) {
 396                     $matches = false;
 397                 }
 398             }
 399             if ($matches) {
 400                 return true;
 401             }
 402         }
 403     }
 404     return false;
 405 }
 406
 407 /**
 408  * Abort execution by throwing of a general exception,
 409  * default exception handler displays the error message in most cases.
 410  *
 411  * @param string $errorcode The name of the language string containing the error message.
 412  *      Normally this should be in the error.php lang file.
 413  * @param string $module The language file to get the error message from.
 414  * @param string $link The url where the user will be prompted to continue.
 415  *      If no url is provided the user will be directed to the site index page.
 416  * @param object $a Extra words and phrases that might be required in the error string
 417  * @param string $debuginfo optional debugging information
 418  * @return void, always throws exception!
 419  */
 420 function print_error($errorcode, $module = 'error', $link = '', $a = null, $debuginfo = null) {
 421     throw new moodle_exception($errorcode, $module, $link, $a, $debuginfo);
 422 }
 423
 424 /**
 425  * Returns detailed information about specified exception.
 426  * @param exception $ex
 427  * @return object
 428  */
 429 function get_exception_info($ex) {
 430     global $CFG, $DB, $SESSION;
 431
 432     if ($ex instanceof moodle_exception) {
 433         $errorcode = $ex->errorcode;
 434         $module = $ex->module;
 435         $a = $ex->a;
 436         $link = $ex->link;
 437         $debuginfo = $ex->debuginfo;
 438     } else {
 439         $errorcode = 'generalexceptionmessage';
 440         $module = 'error';
 441         $a = $ex->getMessage();
 442         $link = '';
 443         $debuginfo = null;
 444     }
 445
 446     $backtrace = $ex->getTrace();
 447     $place = array('file'=>$ex->getFile(), 'line'=>$ex->getLine(), 'exception'=>get_class($ex));
 448     array_unshift($backtrace, $place);
 449
 450     // Be careful, no guarantee moodlelib.php is loaded.
 451     if (empty($module) || $module == 'moodle' || $module == 'core') {
 452         $module = 'error';
 453     }
 454     if (function_exists('get_string_manager')) {
 455         if (get_string_manager()->string_exists($errorcode, $module)) {
 456             $message = get_string($errorcode, $module, $a);
 457         } elseif ($module == 'error' && get_string_manager()->string_exists($errorcode, 'moodle')) {
 458             // Search in moodle file if error specified - needed for backwards compatibility
 459             $message = get_string($errorcode, 'moodle', $a);
 460         } else {
 461             $message = $module . '/' . $errorcode;
 462         }
 463     } else {
 464         $message = $module . '/' . $errorcode;
 465     }
 466
 467     // Be careful, no guarantee weblib.php is loaded.
 468     if (function_exists('clean_text')) {
 469         $message = clean_text($message);
 470     } else {
 471         $message = htmlspecialchars($message);
 472     }
 473
 474     if (!empty($CFG->errordocroot)) {
 475         $errordocroot = $CFG->errordocroot;
 476     } else if (!empty($CFG->docroot)) {
 477         $errordocroot = $CFG->docroot;
 478     } else {
 479         $errordocroot = 'http://docs.moodle.org';
 480     }
 481     if ($module === 'error') {
 482         $modulelink = 'moodle';
 483     } else {
 484         $modulelink = $module;
 485     }
 486     $moreinfourl = $errordocroot . '/en/error/' . $modulelink . '/' . $errorcode;
 487
 488     if (empty($link)) {
 489         if (!empty($SESSION->fromurl)) {
 490             $link = $SESSION->fromurl;
 491             unset($SESSION->fromurl);
 492         } else {
 493             $link = $CFG->wwwroot .'/';
 494         }
 495     }
 496
 497     $info = new stdClass();
 498     $info->message     = $message;
 499     $info->errorcode   = $errorcode;
 500     $info->backtrace   = $backtrace;
 501     $info->link        = $link;
 502     $info->moreinfourl = $moreinfourl;
 503     $info->a           = $a;
 504     $info->debuginfo   = $debuginfo;
 505
 506     return $info;
 507 }
 508
 509 /**
 510  * Formats a backtrace ready for output.
 511  *
 512  * @param array $callers backtrace array, as returned by debug_backtrace().
 513  * @param boolean $plaintext if false, generates HTML, if true generates plain text.
 514  * @return string formatted backtrace, ready for output.
 515  */
 516 function format_backtrace($callers, $plaintext = false) {
 517     // do not use $CFG->dirroot because it might not be available in destructors
 518     $dirroot = dirname(dirname(__FILE__));
 519
 520     if (empty($callers)) {
 521         return '';
 522     }
 523
 524     $from = $plaintext ? '' : '<ul style="text-align: left">';
 525     foreach ($callers as $caller) {
 526         if (!isset($caller['line'])) {
 527             $caller['line'] = '?'; // probably call_user_func()
 528         }
 529         if (!isset($caller['file'])) {
 530             $caller['file'] = 'unknownfile'; // probably call_user_func()
 531         }
 532         $from .= $plaintext ? '* ' : '<li>';
 533         $from .= 'line ' . $caller['line'] . ' of ' . str_replace($dirroot, '', $caller['file']);
 534         if (isset($caller['function'])) {
 535             $from .= ': call to ';
 536             if (isset($caller['class'])) {
 537                 $from .= $caller['class'] . $caller['type'];
 538             }
 539             $from .= $caller['function'] . '()';
 540         } else if (isset($caller['exception'])) {
 541             $from .= ': '.$caller['exception'].' thrown';
 542         }
 543         $from .= $plaintext ? "\n" : '</li>';
 544     }
 545     $from .= $plaintext ? '' : '</ul>';
 546
 547     return $from;
 548 }
 549
 550 /**
 551  * This function makes the return value of ini_get consistent if you are
 552  * setting server directives through the .htaccess file in apache.
 553  *
 554  * Current behavior for value set from php.ini On = 1, Off = [blank]
 555  * Current behavior for value set from .htaccess On = On, Off = Off
 556  * Contributed by jdell @ unr.edu
 557  *
 558  * @param string $ini_get_arg The argument to get
 559  * @return bool True for on false for not
 560  */
 561 function ini_get_bool($ini_get_arg) {
 562     $temp = ini_get($ini_get_arg);
 563
 564     if ($temp == '1' or strtolower($temp) == 'on') {
 565         return true;
 566     }
 567     return false;
 568 }
 569
 570 /**
 571  * This function verifies the sanity of PHP configuration
 572  * and stops execution if anything critical found.
 573  */
 574 function setup_validate_php_configuration() {
 575    // this must be very fast - no slow checks here!!!
 576
 577    if (ini_get_bool('register_globals')) {
 578        print_error('globalswarning', 'admin');
 579    }
 580    if (ini_get_bool('session.auto_start')) {
 581        print_error('sessionautostartwarning', 'admin');
 582    }
 583    if (ini_get_bool('magic_quotes_runtime')) {
 584        print_error('fatalmagicquotesruntime', 'admin');
 585    }
 586 }
 587
 588 /**
 589  * Initialise global $CFG variable
 590  * @return void
 591  */
 592 function initialise_cfg() {
 593     global $CFG, $DB;
 594
 595     try {
 596         if ($DB) {
 597             $localcfg = $DB->get_records_menu('config', array(), '', 'name,value');
 598             foreach ($localcfg as $name=>$value) {
 599                 if (property_exists($CFG, $name)) {
 600                     // config.php settings always take precedence
 601                     continue;
 602                 }
 603                 $CFG->{$name} = $value;
 604             }
 605         }
 606     } catch (dml_read_exception $e) {
 607         // most probably empty db, going to install soon
 608     }
 609 }
 610
 611 /**
 612  * Initialises $FULLME and friends. Private function. Should only be called from
 613  * setup.php.
 614  */
 615 function initialise_fullme() {
 616     global $CFG, $FULLME, $ME, $SCRIPT, $FULLSCRIPT;
 617
 618     // Detect common config error.
 619     if (substr($CFG->wwwroot, -1) == '/') {
 620         print_error('wwwrootslash', 'error');
 621     }
 622
 623     if (CLI_SCRIPT) {
 624         initialise_fullme_cli();
 625         return;
 626     }
 627
 628     $wwwroot = parse_url($CFG->wwwroot);
 629     if (!isset($wwwroot['path'])) {
 630         $wwwroot['path'] = '';
 631     }
 632     $wwwroot['path'] .= '/';
 633
 634     $rurl = setup_get_remote_url();
 635
 636     // Check that URL is under $CFG->wwwroot.
 637     if (strpos($rurl['path'], $wwwroot['path']) === 0) {
 638         $SCRIPT = substr($rurl['path'], strlen($wwwroot['path'])-1);
 639     } else {
 640         // Probably some weird external script
 641         $SCRIPT = $FULLSCRIPT = $FULLME = $ME = null;
 642         return;
 643     }
 644
 645     // $CFG->sslproxy specifies if external SSL appliance is used
 646     // (That is, the Moodle server uses http, with an external box translating everything to https).
 647     if (empty($CFG->sslproxy)) {
 648         if ($rurl['scheme'] === 'http' and $wwwroot['scheme'] === 'https') {
 649             print_error('sslonlyaccess', 'error');
 650         }
 651     } else {
 652         if ($wwwroot['scheme'] !== 'https') {
 653             throw new coding_exception('Must use https address in wwwroot when ssl proxy enabled!');
 654         }
 655         $rurl['scheme'] = 'https'; // make moodle believe it runs on https, squid or something else it doing it
 656     }
 657
 658     // $CFG->reverseproxy specifies if reverse proxy server used.
 659     // Used in load balancing scenarios.
 660     // Do not abuse this to try to solve lan/wan access problems!!!!!
 661     if (empty($CFG->reverseproxy)) {
 662         if (($rurl['host'] != $wwwroot['host']) or
 663                 (!empty($wwwroot['port']) and $rurl['port'] != $wwwroot['port'])) {
 664             // Explain the problem and redirect them to the right URL
 665             if (!defined('NO_MOODLE_COOKIES')) {
 666                 define('NO_MOODLE_COOKIES', true);
 667             }
 668             redirect($CFG->wwwroot, get_string('wwwrootmismatch', 'error', $CFG->wwwroot), 3);
 669         }
 670     }
 671
 672     // hopefully this will stop all those "clever" admins trying to set up moodle
 673     // with two different addresses in intranet and Internet
 674     if (!empty($CFG->reverseproxy) && $rurl['host'] == $wwwroot['host']) {
 675         print_error('reverseproxyabused', 'error');
 676     }
 677
 678     $hostandport = $rurl['scheme'] . '://' . $wwwroot['host'];
 679     if (!empty($wwwroot['port'])) {
 680         $hostandport .= ':'.$wwwroot['port'];
 681     }
 682
 683     $FULLSCRIPT = $hostandport . $rurl['path'];
 684     $FULLME = $hostandport . $rurl['fullpath'];
 685     $ME = $rurl['fullpath'];
 686     $rurl['path'] = $rurl['fullpath'];
 687 }
 688
 689 /**
 690  * Initialises $FULLME and friends for command line scripts.
 691  * This is a private method for use by initialise_fullme.
 692  */
 693 function initialise_fullme_cli() {
 694     global $CFG, $FULLME, $ME, $SCRIPT, $FULLSCRIPT;
 695
 696     // Urls do not make much sense in CLI scripts
 697     $backtrace = debug_backtrace();
 698     $topfile = array_pop($backtrace);
 699     $topfile = realpath($topfile['file']);
 700     $dirroot = realpath($CFG->dirroot);
 701
 702     if (strpos($topfile, $dirroot) !== 0) {
 703         // Probably some weird external script
 704         $SCRIPT = $FULLSCRIPT = $FULLME = $ME = null;
 705     } else {
 706         $relativefile = substr($topfile, strlen($dirroot));
 707         $relativefile = str_replace('\\', '/', $relativefile); // Win fix
 708         $SCRIPT = $FULLSCRIPT = $relativefile;
 709         $FULLME = $ME = null;
 710     }
 711 }
 712
 713 /**
 714  * Get the URL that PHP/the web server thinks it is serving. Private function
 715  * used by initialise_fullme. In your code, use $PAGE->url, $SCRIPT, etc.
 716  * @return array in the same format that parse_url returns, with the addition of
 717  *      a 'fullpath' element, which includes any slasharguments path.
 718  */
 719 function setup_get_remote_url() {
 720     $rurl = array();
 721     list($rurl['host']) = explode(':', $_SERVER['HTTP_HOST']);
 722     $rurl['port'] = $_SERVER['SERVER_PORT'];
 723     $rurl['path'] = $_SERVER['SCRIPT_NAME']; // Script path without slash arguments
 724
 725     if (stripos($_SERVER['SERVER_SOFTWARE'], 'apache') !== false) {
 726         //Apache server
 727         $rurl['scheme']   = empty($_SERVER['HTTPS']) ? 'http' : 'https';
 728         $rurl['fullpath'] = $_SERVER['REQUEST_URI'];
 729
 730     } else if (stripos($_SERVER['SERVER_SOFTWARE'], 'iis') !== false) {
 731         //IIS - needs a lot of tweaking to make it work
 732         $rurl['scheme']   = ($_SERVER['HTTPS'] == 'off') ? 'http' : 'https';
 733         $rurl['fullpath'] = $_SERVER['SCRIPT_NAME'];
 734
 735         // NOTE: ignore PATH_INFO because it is incorrectly encoded using 8bit filesystem legacy encoding in IIS
 736         //       since 2.0 we rely on iis rewrite extenssion like Helicon ISAPI_rewrite
 737         //       example rule: RewriteRule ^([^\?]+?\.php)(\/.+)$ $1\?file=$2 [QSA]
 738
 739         if ($_SERVER['QUERY_STRING'] != '') {
 740             $rurl['fullpath'] .= '?'.$_SERVER['QUERY_STRING'];
 741         }
 742         $_SERVER['REQUEST_URI'] = $rurl['fullpath']; // extra IIS compatibility
 743
 744 /* NOTE: following servers are not fully tested! */
 745
 746     } else if (stripos($_SERVER['SERVER_SOFTWARE'], 'lighttpd') !== false) {
 747         //lighttpd - not officially supported
 748         $rurl['scheme']   = empty($_SERVER['HTTPS']) ? 'http' : 'https';
 749         $rurl['fullpath'] = $_SERVER['REQUEST_URI']; // TODO: verify this is always properly encoded
 750
 751     } else if (stripos($_SERVER['SERVER_SOFTWARE'], 'nginx') !== false) {
 752         //nginx - not officially supported
 753         $rurl['scheme']   = empty($_SERVER['HTTPS']) ? 'http' : 'https';
 754         $rurl['fullpath'] = $_SERVER['REQUEST_URI']; // TODO: verify this is always properly encoded
 755
 756      } else if (stripos($_SERVER['SERVER_SOFTWARE'], 'cherokee') !== false) {
 757          //cherokee - not officially supported
 758          $rurl['scheme']   = ($_SERVER['HTTPS'] == 'off') ? 'http' : 'https';
 759          $rurl['fullpath'] = $_SERVER['REQUEST_URI']; // TODO: verify this is always properly encoded
 760
 761      } else if (stripos($_SERVER['SERVER_SOFTWARE'], 'zeus') !== false) {
 762          //zeus - not officially supported
 763          $rurl['scheme']   = ($_SERVER['HTTPS'] == 'off') ? 'http' : 'https';
 764          $rurl['fullpath'] = $_SERVER['REQUEST_URI']; // TODO: verify this is always properly encoded
 765
 766     } else if (stripos($_SERVER['SERVER_SOFTWARE'], 'LiteSpeed') !== false) {
 767         //LiteSpeed - not officially supported
 768         $rurl['scheme']   = ($_SERVER['HTTPS'] == 'off') ? 'http' : 'https';
 769         $rurl['fullpath'] = $_SERVER['REQUEST_URI']; // TODO: verify this is always properly encoded
 770
 771      } else {
 772         throw new moodle_exception('unsupportedwebserver', 'error', '', $_SERVER['SERVER_SOFTWARE']);
 773     }
 774     return $rurl;
 775 }
 776
 777 /**
 778  * Initializes our performance info early.
 779  *
 780  * Pairs up with get_performance_info() which is actually
 781  * in moodlelib.php. This function is here so that we can
 782  * call it before all the libs are pulled in.
 783  *
 784  * @uses $PERF
 785  */
 786 function init_performance_info() {
 787
 788     global $PERF, $CFG, $USER;
 789
 790     $PERF = new stdClass();
 791     $PERF->logwrites = 0;
 792     if (function_exists('microtime')) {
 793         $PERF->starttime = microtime();
 794     }
 795     if (function_exists('memory_get_usage')) {
 796         $PERF->startmemory = memory_get_usage();
 797     }
 798     if (function_exists('posix_times')) {
 799         $PERF->startposixtimes = posix_times();
 800     }
 801     if (function_exists('apd_set_pprof_trace')) {
 802         // APD profiling
 803         if ($USER->id > 0 && $CFG->perfdebug >= 15) {
 804             $tempdir = $CFG->dataroot . '/temp/profile/' . $USER->id;
 805             mkdir($tempdir);
 806             apd_set_pprof_trace($tempdir);
 807             $PERF->profiling = true;
 808         }
 809     }
 810 }
 811
 812 /**
 813  * Indicates whether we are in the middle of the initial Moodle install.
 814  *
 815  * Very occasionally it is necessary avoid running certain bits of code before the
 816  * Moodle installation has completed. The installed flag is set in admin/index.php
 817  * after Moodle core and all the plugins have been installed, but just before
 818  * the person doing the initial install is asked to choose the admin password.
 819  *
 820  * @return boolean true if the initial install is not complete.
 821  */
 822 function during_initial_install() {
 823     global $CFG;
 824     return empty($CFG->rolesactive);
 825 }
 826
 827 /**
 828  * Function to raise the memory limit to a new value.
 829  * Will respect the memory limit if it is higher, thus allowing
 830  * settings in php.ini, apache conf or command line switches
 831  * to override it.
 832  *
 833  * The memory limit should be expressed with a constant
 834  * MEMORY_STANDARD, MEMORY_EXTRA or MEMORY_HUGE.
 835  * It is possible to use strings or integers too (eg:'128M').
 836  *
 837  * @param mixed $newlimit the new memory limit
 838  * @return bool success
 839  */
 840 function raise_memory_limit($newlimit) {
 841     global $CFG;
 842
 843     if ($newlimit == MEMORY_UNLIMITED) {
 844         ini_set('memory_limit', -1);
 845         return true;
 846
 847     } else if ($newlimit == MEMORY_STANDARD) {
 848         if (PHP_INT_SIZE > 4) {
 849             $newlimit = get_real_size('128M'); // 64bit needs more memory
 850         } else {
 851             $newlimit = get_real_size('96M');
 852         }
 853
 854     } else if ($newlimit == MEMORY_EXTRA) {
 855         if (PHP_INT_SIZE > 4) {
 856             $newlimit = get_real_size('384M'); // 64bit needs more memory
 857         } else {
 858             $newlimit = get_real_size('256M');
 859         }
 860         if (!empty($CFG->extramemorylimit)) {
 861             $extra = get_real_size($CFG->extramemorylimit);
 862             if ($extra > $newlimit) {
 863                 $newlimit = $extra;
 864             }
 865         }
 866
 867     } else if ($newlimit == MEMORY_HUGE) {
 868         $newlimit = get_real_size('2G');
 869
 870     } else {
 871         $newlimit = get_real_size($newlimit);
 872     }
 873
 874     if ($newlimit <= 0) {
 875         debugging('Invalid memory limit specified.');
 876         return false;
 877     }
 878
 879     $cur = ini_get('memory_limit');
 880     if (empty($cur)) {
 881         // if php is compiled without --enable-memory-limits
 882         // apparently memory_limit is set to ''
 883         $cur = 0;
 884     } else {
 885         if ($cur == -1){
 886             return true; // unlimited mem!
 887         }
 888         $cur = get_real_size($cur);
 889     }
 890
 891     if ($newlimit > $cur) {
 892         ini_set('memory_limit', $newlimit);
 893         return true;
 894     }
 895     return false;
 896 }
 897
 898 /**
 899  * Function to reduce the memory limit to a new value.
 900  * Will respect the memory limit if it is lower, thus allowing
 901  * settings in php.ini, apache conf or command line switches
 902  * to override it
 903  *
 904  * The memory limit should be expressed with a string (eg:'64M')
 905  *
 906  * @param string $newlimit the new memory limit
 907  * @return bool
 908  */
 909 function reduce_memory_limit($newlimit) {
 910     if (empty($newlimit)) {
 911         return false;
 912     }
 913     $cur = ini_get('memory_limit');
 914     if (empty($cur)) {
 915         // if php is compiled without --enable-memory-limits
 916         // apparently memory_limit is set to ''
 917         $cur = 0;
 918     } else {
 919         if ($cur == -1){
 920             return true; // unlimited mem!
 921         }
 922         $cur = get_real_size($cur);
 923     }
 924
 925     $new = get_real_size($newlimit);
 926     // -1 is smaller, but it means unlimited
 927     if ($new < $cur && $new != -1) {
 928         ini_set('memory_limit', $newlimit);
 929         return true;
 930     }
 931     return false;
 932 }
 933
 934 /**
 935  * Converts numbers like 10M into bytes.
 936  *
 937  * @param string $size The size to be converted
 938  * @return int
 939  */
 940 function get_real_size($size = 0) {
 941     if (!$size) {
 942         return 0;
 943     }
 944     $scan = array();
 945     $scan['GB'] = 1073741824;
 946     $scan['Gb'] = 1073741824;
 947     $scan['G'] = 1073741824;
 948     $scan['MB'] = 1048576;
 949     $scan['Mb'] = 1048576;
 950     $scan['M'] = 1048576;
 951     $scan['m'] = 1048576;
 952     $scan['KB'] = 1024;
 953     $scan['Kb'] = 1024;
 954     $scan['K'] = 1024;
 955     $scan['k'] = 1024;
 956
 957     while (list($key) = each($scan)) {
 958         if ((strlen($size)>strlen($key))&&(substr($size, strlen($size) - strlen($key))==$key)) {
 959             $size = substr($size, 0, strlen($size) - strlen($key)) * $scan[$key];
 960             break;
 961         }
 962     }
 963     return $size;
 964 }
 965
 966 /**
 967  * Try to disable all output buffering and purge
 968  * all headers.
 969  *
 970  * @private to be called only from lib/setup.php !
 971  * @return void
 972  */
 973 function disable_output_buffering() {
 974     $olddebug = error_reporting(0);
 975
 976     // disable compression, it would prevent closing of buffers
 977     if (ini_get_bool('zlib.output_compression')) {
 978         ini_set('zlib.output_compression', 'Off');
 979     }
 980
 981     // try to flush everything all the time
 982     ob_implicit_flush(true);
 983
 984     // close all buffers if possible and discard any existing output
 985     // this can actually work around some whitespace problems in config.php
 986     while(ob_get_level()) {
 987         if (!ob_end_clean()) {
 988             // prevent infinite loop when buffer can not be closed
 989             break;
 990         }
 991     }
 992
 993     error_reporting($olddebug);
 994 }
 995
 996 /**
 997  * Check whether a major upgrade is needed. That is defined as an upgrade that
 998  * changes something really fundamental in the database, so nothing can possibly
 999  * work until the database has been updated, and that is defined by the hard-coded
1000  * version number in this function.
1001  */
1002 function redirect_if_major_upgrade_required() {
1003     global $CFG;
1004     $lastmajordbchanges = 2010111700;
1005     if (empty($CFG->version) or (int)$CFG->version < $lastmajordbchanges or
1006             during_initial_install() or !empty($CFG->adminsetuppending)) {
1007         try {
1008             @session_get_instance()->terminate_current();
1009         } catch (Exception $e) {
1010             // Ignore any errors, redirect to upgrade anyway.
1011         }
1012         $url = $CFG->wwwroot . '/' . $CFG->admin . '/index.php';
1013         @header($_SERVER['SERVER_PROTOCOL'] . ' 303 See Other');
1014         @header('Location: ' . $url);
1015         echo bootstrap_renderer::plain_redirect_message(htmlspecialchars($url));
1016         exit;
1017     }
1018 }
1019
1020 /**
1021  * Function to check if a directory exists and by default create it if not exists.
1022  *
1023  * Previously this was accepting paths only from dataroot, but we now allow
1024  * files outside of dataroot if you supply custom paths for some settings in config.php.
1025  * This function does not verify that the directory is writable.
1026  *
1027  * @param string $dir absolute directory path
1028  * @param boolean $create directory if does not exist
1029  * @param boolean $recursive create directory recursively
1030  * @return boolean true if directory exists or created, false otherwise
1031  */
1032 function check_dir_exists($dir, $create = true, $recursive = true) {
1033     global $CFG;
1034
1035     umask(0000); // just in case some evil code changed it
1036
1037     if (is_dir($dir)) {
1038         return true;
1039     }
1040
1041     if (!$create) {
1042         return false;
1043     }
1044
1045     return mkdir($dir, $CFG->directorypermissions, $recursive);
1046 }
1047
1048 /**
1049  * Create a directory in dataroot and make sure it is writable.
1050  *
1051  * @param string $directory  a string of directory names under $CFG->dataroot eg  temp/something
1052  * @param bool $exceptiononerror throw exception if error encountered
1053  * @return string|false Returns full path to directory if successful, false if not; may throw exception
1054  */
1055 function make_upload_directory($directory, $exceptiononerror = true) {
1056     global $CFG;
1057
1058     // Make sure a .htaccess file is here, JUST IN CASE the files area is in the open and .htaccess is supported
1059     if (!file_exists("$CFG->dataroot/.htaccess")) {
1060         if ($handle = fopen("$CFG->dataroot/.htaccess", 'w')) {   // For safety
1061             @fwrite($handle, "deny from all\r\nAllowOverride None\r\nNote: this file is broken intentionally, we do not want anybody to undo it in subdirectory!\r\n");
1062             @fclose($handle);
1063         }
1064     }
1065
1066     $dir = "$CFG->dataroot/$directory";
1067
1068     if (file_exists($dir) and !is_dir($dir)) {
1069         if ($exceptiononerror) {
1070             throw new coding_exception($dir.' directory can not be created, file with the same name already exists.');
1071         } else {
1072             return false;
1073         }
1074     }
1075
1076     umask(0000); // just in case some evil code changed it
1077
1078     if (!file_exists($dir)) {
1079         if (!mkdir($dir, $CFG->directorypermissions, true)) {
1080             if ($exceptiononerror) {
1081                 throw new invalid_dataroot_permissions($dir.' can not be created, check permissions.');
1082             } else {
1083                 return false;
1084             }
1085         }
1086     }
1087
1088     if (!is_writable($dir)) {
1089         if ($exceptiononerror) {
1090             throw new invalid_dataroot_permissions($dir.' is not writable, check permissions.');
1091         } else {
1092             return false;
1093         }
1094     }
1095
1096     return $dir;
1097 }
1098
1099 function init_memcached() {
1100     global $CFG, $MCACHE;
1101
1102     include_once($CFG->libdir . '/memcached.class.php');
1103     $MCACHE = new memcached;
1104     if ($MCACHE->status()) {
1105         return true;
1106     }
1107     unset($MCACHE);
1108     return false;
1109 }
1110
1111 function init_eaccelerator() {
1112     global $CFG, $MCACHE;
1113
1114     include_once($CFG->libdir . '/eaccelerator.class.php');
1115     $MCACHE = new eaccelerator;
1116     if ($MCACHE->status()) {
1117         return true;
1118     }
1119     unset($MCACHE);
1120     return false;
1121 }
1122
1123
1124 /**
1125  * This class solves the problem of how to initialise $OUTPUT.
1126  *
1127  * The problem is caused be two factors
1128  * <ol>
1129  * <li>On the one hand, we cannot be sure when output will start. In particular,
1130  * an error, which needs to be displayed, could be thrown at any time.</li>
1131  * <li>On the other hand, we cannot be sure when we will have all the information
1132  * necessary to correctly initialise $OUTPUT. $OUTPUT depends on the theme, which
1133  * (potentially) depends on the current course, course categories, and logged in user.
1134  * It also depends on whether the current page requires HTTPS.</li>
1135  * </ol>
1136  *
1137  * So, it is hard to find a single natural place during Moodle script execution,
1138  * which we can guarantee is the right time to initialise $OUTPUT. Instead we
1139  * adopt the following strategy
1140  * <ol>
1141  * <li>We will initialise $OUTPUT the first time it is used.</li>
1142  * <li>If, after $OUTPUT has been initialised, the script tries to change something
1143  * that $OUTPUT depends on, we throw an exception making it clear that the script
1144  * did something wrong.
1145  * </ol>
1146  *
1147  * The only problem with that is, how do we initialise $OUTPUT on first use if,
1148  * it is going to be used like $OUTPUT->somthing(...)? Well that is where this
1149  * class comes in. Initially, we set up $OUTPUT = new bootstrap_renderer(). Then,
1150  * when any method is called on that object, we initialise $OUTPUT, and pass the call on.
1151  *
1152  * Note that this class is used before lib/outputlib.php has been loaded, so we
1153  * must be careful referring to classes/functions from there, they may not be
1154  * defined yet, and we must avoid fatal errors.
1155  *
1156  * @copyright 2009 Tim Hunt
1157  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
1158  * @since     Moodle 2.0
1159  */
1160 class bootstrap_renderer {
1161     /**
1162      * Handles re-entrancy. Without this, errors or debugging output that occur
1163      * during the initialisation of $OUTPUT, cause infinite recursion.
1164      * @var boolean
1165      */
1166     protected $initialising = false;
1167
1168     /**
1169      * Have we started output yet?
1170      * @return boolean true if the header has been printed.
1171      */
1172     public function has_started() {
1173         return false;
1174     }
1175
1176     public function __call($method, $arguments) {
1177         global $OUTPUT, $PAGE;
1178
1179         $recursing = false;
1180         if ($method == 'notification') {
1181             // Catch infinite recursion caused by debugging output during print_header.
1182             $backtrace = debug_backtrace();
1183             array_shift($backtrace);
1184             array_shift($backtrace);
1185             $recursing = is_early_init($backtrace);
1186         }
1187
1188         $earlymethods = array(
1189             'fatal_error' => 'early_error',
1190             'notification' => 'early_notification',
1191         );
1192
1193         // If lib/outputlib.php has been loaded, call it.
1194         if (!empty($PAGE) && !$recursing) {
1195             if (array_key_exists($method, $earlymethods)) {
1196                 //prevent PAGE->context warnings - exceptions might appear before we set any context
1197                 $PAGE->set_context(null);
1198             }
1199             $PAGE->initialise_theme_and_output();
1200             return call_user_func_array(array($OUTPUT, $method), $arguments);
1201         }
1202
1203         $this->initialising = true;
1204
1205         // Too soon to initialise $OUTPUT, provide a couple of key methods.
1206         if (array_key_exists($method, $earlymethods)) {
1207             return call_user_func_array(array('bootstrap_renderer', $earlymethods[$method]), $arguments);
1208         }
1209
1210         throw new coding_exception('Attempt to start output before enough information is known to initialise the theme.');
1211     }
1212
1213     /**
1214      * Returns nicely formatted error message in a div box.
1215      * @return string
1216      */
1217     public static function early_error_content($message, $moreinfourl, $link, $backtrace, $debuginfo = null) {
1218         global $CFG;
1219
1220         $content = '<div style="margin-top: 6em; margin-left:auto; margin-right:auto; color:#990000; text-align:center; font-size:large; border-width:1px;
1221 border-color:black; background-color:#ffffee; border-style:solid; border-radius: 20px; border-collapse: collapse;
1222 width: 80%; -moz-border-radius: 20px; padding: 15px">
1223 ' . $message . '
1224 </div>';
1225         if (!empty($CFG->debug) && $CFG->debug >= DEBUG_DEVELOPER) {
1226             if (!empty($debuginfo)) {
1227                 $debuginfo = s($debuginfo); // removes all nasty JS
1228                 $debuginfo = str_replace("\n", '<br />', $debuginfo); // keep newlines
1229                 $content .= '<div class="notifytiny">Debug info: ' . $debuginfo . '</div>';
1230             }
1231             if (!empty($backtrace)) {
1232                 $content .= '<div class="notifytiny">Stack trace: ' . format_backtrace($backtrace, false) . '</div>';
1233             }
1234         }
1235
1236         return $content;
1237     }
1238
1239     /**
1240      * This function should only be called by this class, or from exception handlers
1241      * @return string
1242      */
1243     public static function early_error($message, $moreinfourl, $link, $backtrace, $debuginfo = null) {
1244         global $CFG;
1245
1246         if (CLI_SCRIPT) {
1247             echo "!!! $message !!!\n";
1248             if (!empty($CFG->debug) and $CFG->debug >= DEBUG_DEVELOPER) {
1249                 if (!empty($debuginfo)) {
1250                     echo "\nDebug info: $debuginfo";
1251                 }
1252                 if (!empty($backtrace)) {
1253                     echo "\nStack trace: " . format_backtrace($backtrace, true);
1254                 }
1255             }
1256             return;
1257
1258         } else if (AJAX_SCRIPT) {
1259             $e = new stdClass();
1260             $e->error      = $message;
1261             $e->stacktrace = NULL;
1262             $e->debuginfo  = NULL;
1263             if (!empty($CFG->debug) and $CFG->debug >= DEBUG_DEVELOPER) {
1264                 if (!empty($debuginfo)) {
1265                     $e->debuginfo = $debuginfo;
1266                 }
1267                 if (!empty($backtrace)) {
1268                     $e->stacktrace = format_backtrace($backtrace, true);
1269                 }
1270             }
1271             @header('Content-Type: application/json');
1272             echo json_encode($e);
1273             return;
1274         }
1275
1276         // In the name of protocol correctness, monitoring and performance
1277         // profiling, set the appropriate error headers for machine consumption
1278         if (isset($_SERVER['SERVER_PROTOCOL'])) {
1279             // Avoid it with cron.php. Note that we assume it's HTTP/1.x
1280             // The 503 ode here means our Moodle does not work at all, the error happened too early
1281             @header($_SERVER['SERVER_PROTOCOL'] . ' 503 Service Unavailable');
1282         }
1283
1284         // better disable any caching
1285         @header('Content-Type: text/html; charset=utf-8');
1286         @header('Cache-Control: no-store, no-cache, must-revalidate');
1287         @header('Cache-Control: post-check=0, pre-check=0', false);
1288         @header('Pragma: no-cache');
1289         @header('Expires: Mon, 20 Aug 1969 09:23:00 GMT');
1290         @header('Last-Modified: ' . gmdate('D, d M Y H:i:s') . ' GMT');
1291
1292         if (function_exists('get_string')) {
1293             $strerror = get_string('error');
1294         } else {
1295             $strerror = 'Error';
1296         }
1297
1298         $content = self::early_error_content($message, $moreinfourl, $link, $backtrace, $debuginfo);
1299
1300         return self::plain_page($strerror, $content);
1301     }
1302
1303     public static function early_notification($message, $classes = 'notifyproblem') {
1304         return '<div class="' . $classes . '">' . $message . '</div>';
1305     }
1306
1307     public static function plain_redirect_message($encodedurl) {
1308         $message = '<p>' . get_string('pageshouldredirect') . '</p><p><a href="'.
1309                 $encodedurl .'">'. get_string('continue') .'</a></p>';
1310         return self::plain_page(get_string('redirect'), $message);
1311     }
1312
1313     protected static function plain_page($title, $content) {
1314         if (function_exists('get_string') && function_exists('get_html_lang')) {
1315             $htmllang = get_html_lang();
1316         } else {
1317             $htmllang = '';
1318         }
1319
1320         return '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
1321 <html xmlns="http://www.w3.org/1999/xhtml" ' . $htmllang . '>
1322 <head>
1323 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
1324 <title>' . $title . '</title>
1325 </head><body>' . $content . '</body></html>';
1326     }
1327 }