includes/Exception.php

   1 <?php
   2 /**
   3  * Exception class and handler.
   4  *
   5  * This program 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 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program 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 along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 /**
  24  * @defgroup Exception Exception
  25  */
  26
  27 /**
  28  * MediaWiki exception
  29  *
  30  * @ingroup Exception
  31  */
  32 class MWException extends Exception {
  33         var $logId;
  34
  35         /**
  36          * Should the exception use $wgOut to output the error?
  37          *
  38          * @return bool
  39          */
  40         function useOutputPage() {
  41                 return $this->useMessageCache() &&
  42                         !empty( $GLOBALS['wgFullyInitialised'] ) &&
  43                         !empty( $GLOBALS['wgOut'] ) &&
  44                         !empty( $GLOBALS['wgTitle'] );
  45         }
  46
  47         /**
  48          * Can the extension use the Message class/wfMessage to get i18n-ed messages?
  49          *
  50          * @return bool
  51          */
  52         function useMessageCache() {
  53                 global $wgLang;
  54
  55                 foreach ( $this->getTrace() as $frame ) {
  56                         if ( isset( $frame['class'] ) && $frame['class'] === 'LocalisationCache' ) {
  57                                 return false;
  58                         }
  59                 }
  60
  61                 return $wgLang instanceof Language;
  62         }
  63
  64         /**
  65          * Run hook to allow extensions to modify the text of the exception
  66          *
  67          * @param $name string: class name of the exception
  68          * @param $args array: arguments to pass to the callback functions
  69          * @return string|null string to output or null if any hook has been called
  70          */
  71         function runHooks( $name, $args = array() ) {
  72                 global $wgExceptionHooks;
  73
  74                 if ( !isset( $wgExceptionHooks ) || !is_array( $wgExceptionHooks ) ) {
  75                         return null; // Just silently ignore
  76                 }
  77
  78                 if ( !array_key_exists( $name, $wgExceptionHooks ) || !is_array( $wgExceptionHooks[ $name ] ) ) {
  79                         return null;
  80                 }
  81
  82                 $hooks = $wgExceptionHooks[ $name ];
  83                 $callargs = array_merge( array( $this ), $args );
  84
  85                 foreach ( $hooks as $hook ) {
  86                         if ( is_string( $hook ) || ( is_array( $hook ) && count( $hook ) >= 2 && is_string( $hook[0] ) ) ) {    // 'function' or array( 'class', hook' )
  87                                 $result = call_user_func_array( $hook, $callargs );
  88                         } else {
  89                                 $result = null;
  90                         }
  91
  92                         if ( is_string( $result ) ) {
  93                                 return $result;
  94                         }
  95                 }
  96                 return null;
  97         }
  98
  99         /**
 100          * Get a message from i18n
 101          *
 102          * @param $key string: message name
 103          * @param $fallback string: default message if the message cache can't be
 104          *                  called by the exception
 105          * The function also has other parameters that are arguments for the message
 106          * @return string message with arguments replaced
 107          */
 108         function msg( $key, $fallback /*[, params...] */ ) {
 109                 $args = array_slice( func_get_args(), 2 );
 110
 111                 if ( $this->useMessageCache() ) {
 112                         return wfMessage( $key, $args )->plain();
 113                 } else {
 114                         return wfMsgReplaceArgs( $fallback, $args );
 115                 }
 116         }
 117
 118         /**
 119          * If $wgShowExceptionDetails is true, return a HTML message with a
 120          * backtrace to the error, otherwise show a message to ask to set it to true
 121          * to show that information.
 122          *
 123          * @return string html to output
 124          */
 125         function getHTML() {
 126                 global $wgShowExceptionDetails;
 127
 128                 if ( $wgShowExceptionDetails ) {
 129                         return '<p>' . nl2br( htmlspecialchars( $this->getMessage() ) ) .
 130                                 '</p><p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) ) .
 131                                 "</p>\n";
 132                 } else {
 133                         return
 134                                 "<div class=\"errorbox\">" .
 135                                 '[' . $this->getLogId() . '] ' .
 136                                 gmdate( 'Y-m-d H:i:s' ) .
 137                                 ": Fatal exception of type " . get_class( $this ) . "</div>\n" .
 138                                 "<!-- Set \$wgShowExceptionDetails = true; " .
 139                                 "at the bottom of LocalSettings.php to show detailed " .
 140                                 "debugging information. -->";
 141                 }
 142         }
 143
 144         /**
 145          * Get the text to display when reporting the error on the command line.
 146          * If $wgShowExceptionDetails is true, return a text message with a
 147          * backtrace to the error.
 148          *
 149          * @return string
 150          */
 151         function getText() {
 152                 global $wgShowExceptionDetails;
 153
 154                 if ( $wgShowExceptionDetails ) {
 155                         return $this->getMessage() .
 156                                 "\nBacktrace:\n" . $this->getTraceAsString() . "\n";
 157                 } else {
 158                         return "Set \$wgShowExceptionDetails = true; " .
 159                                 "in LocalSettings.php to show detailed debugging information.\n";
 160                 }
 161         }
 162
 163         /**
 164          * Return the title of the page when reporting this error in a HTTP response.
 165          *
 166          * @return string
 167          */
 168         function getPageTitle() {
 169                 return $this->msg( 'internalerror', "Internal error" );
 170         }
 171
 172         /**
 173          * Get a random ID for this error.
 174          * This allows to link the exception to its correspoding log entry when
 175          * $wgShowExceptionDetails is set to false.
 176          *
 177          * @return string
 178          */
 179         function getLogId() {
 180                 if ( $this->logId === null ) {
 181                         $this->logId = wfRandomString( 8 );
 182                 }
 183                 return $this->logId;
 184         }
 185
 186         /**
 187          * Return the requested URL and point to file and line number from which the
 188          * exception occurred
 189          *
 190          * @return string
 191          */
 192         function getLogMessage() {
 193                 global $wgRequest;
 194
 195                 $id = $this->getLogId();
 196                 $file = $this->getFile();
 197                 $line = $this->getLine();
 198                 $message = $this->getMessage();
 199
 200                 if ( isset( $wgRequest ) && !$wgRequest instanceof FauxRequest ) {
 201                         $url = $wgRequest->getRequestURL();
 202                         if ( !$url ) {
 203                                 $url = '[no URL]';
 204                         }
 205                 } else {
 206                         $url = '[no req]';
 207                 }
 208
 209                 return "[$id] $url   Exception from line $line of $file: $message";
 210         }
 211
 212         /**
 213          * Output the exception report using HTML.
 214          */
 215         function reportHTML() {
 216                 global $wgOut;
 217                 if ( $this->useOutputPage() ) {
 218                         $wgOut->prepareErrorPage( $this->getPageTitle() );
 219
 220                         $hookResult = $this->runHooks( get_class( $this ) );
 221                         if ( $hookResult ) {
 222                                 $wgOut->addHTML( $hookResult );
 223                         } else {
 224                                 $wgOut->addHTML( $this->getHTML() );
 225                         }
 226
 227                         $wgOut->output();
 228                 } else {
 229                         header( "Content-Type: text/html; charset=utf-8" );
 230                         echo "<!doctype html>\n" .
 231                                 '<html><head>' .
 232                                 '<title>' . htmlspecialchars( $this->getPageTitle() ) . '</title>' .
 233                                 "</head><body>\n";
 234
 235                         $hookResult = $this->runHooks( get_class( $this ) . "Raw" );
 236                         if ( $hookResult ) {
 237                                 echo $hookResult;
 238                         } else {
 239                                 echo $this->getHTML();
 240                         }
 241
 242                         echo "</body></html>\n";
 243                 }
 244         }
 245
 246         /**
 247          * Output a report about the exception and takes care of formatting.
 248          * It will be either HTML or plain text based on isCommandLine().
 249          */
 250         function report() {
 251                 global $wgLogExceptionBacktrace;
 252                 $log = $this->getLogMessage();
 253
 254                 if ( $log ) {
 255                         if ( $wgLogExceptionBacktrace ) {
 256                                 wfDebugLog( 'exception', $log . "\n" . $this->getTraceAsString() . "\n" );
 257                         } else {
 258                                 wfDebugLog( 'exception', $log );
 259                         }
 260                 }
 261
 262                 if ( defined( 'MW_API' ) ) {
 263                         // Unhandled API exception, we can't be sure that format printer is alive
 264                         header( 'MediaWiki-API-Error: internal_api_error_' . get_class( $this ) );
 265                         wfHttpError(500, 'Internal Server Error', $this->getText() );
 266                 } elseif ( self::isCommandLine() ) {
 267                         MWExceptionHandler::printError( $this->getText() );
 268                 } else {
 269                         header( "HTTP/1.1 500 MediaWiki exception" );
 270                         header( "Status: 500 MediaWiki exception", true );
 271
 272                         $this->reportHTML();
 273                 }
 274         }
 275
 276         /**
 277          * Check whether we are in command line mode or not to report the exception
 278          * in the correct format.
 279          *
 280          * @return bool
 281          */
 282         static function isCommandLine() {
 283                 return !empty( $GLOBALS['wgCommandLineMode'] );
 284         }
 285 }
 286
 287 /**
 288  * Exception class which takes an HTML error message, and does not
 289  * produce a backtrace. Replacement for OutputPage::fatalError().
 290  *
 291  * @since 1.7
 292  * @ingroup Exception
 293  */
 294 class FatalError extends MWException {
 295
 296         /**
 297          * @return string
 298          */
 299         function getHTML() {
 300                 return $this->getMessage();
 301         }
 302
 303         /**
 304          * @return string
 305          */
 306         function getText() {
 307                 return $this->getMessage();
 308         }
 309 }
 310
 311 /**
 312  * An error page which can definitely be safely rendered using the OutputPage.
 313  *
 314  * @since 1.7
 315  * @ingroup Exception
 316  */
 317 class ErrorPageError extends MWException {
 318         public $title, $msg, $params;
 319
 320         /**
 321          * Note: these arguments are keys into wfMessage(), not text!
 322          *
 323          * @param $title string|Message Message key (string) for page title, or a Message object
 324          * @param $msg string|Message Message key (string) for error text, or a Message object
 325          * @param $params array with parameters to wfMessage()
 326          */
 327         function __construct( $title, $msg, $params = null ) {
 328                 $this->title = $title;
 329                 $this->msg = $msg;
 330                 $this->params = $params;
 331
 332                 if( $msg instanceof Message ) {
 333                         parent::__construct( $msg );
 334                 } else {
 335                         parent::__construct( wfMessage( $msg )->text() );
 336                 }
 337         }
 338
 339         function report() {
 340                 global $wgOut;
 341
 342                 $wgOut->showErrorPage( $this->title, $this->msg, $this->params );
 343                 $wgOut->output();
 344         }
 345 }
 346
 347 /**
 348  * Show an error page on a badtitle.
 349  * Similar to ErrorPage, but emit a 400 HTTP error code to let mobile
 350  * browser it is not really a valid content.
 351  *
 352  * @since 1.19
 353  * @ingroup Exception
 354  */
 355 class BadTitleError extends ErrorPageError {
 356         /**
 357          * @param $msg string|Message A message key (default: 'badtitletext')
 358          * @param $params Array parameter to wfMessage()
 359          */
 360         function __construct( $msg = 'badtitletext', $params = null ) {
 361                 parent::__construct( 'badtitle', $msg, $params );
 362         }
 363
 364         /**
 365          * Just like ErrorPageError::report() but additionally set
 366          * a 400 HTTP status code (bug 33646).
 367          */
 368         function report() {
 369                 global $wgOut;
 370
 371                 // bug 33646: a badtitle error page need to return an error code
 372                 // to let mobile browser now that it is not a normal page.
 373                 $wgOut->setStatusCode( 400 );
 374                 parent::report();
 375         }
 376
 377 }
 378
 379 /**
 380  * Show an error when a user tries to do something they do not have the necessary
 381  * permissions for.
 382  *
 383  * @since 1.18
 384  * @ingroup Exception
 385  */
 386 class PermissionsError extends ErrorPageError {
 387         public $permission, $errors;
 388
 389         function __construct( $permission, $errors = array() ) {
 390                 global $wgLang;
 391
 392                 $this->permission = $permission;
 393
 394                 if ( !count( $errors ) ) {
 395                         $groups = array_map(
 396                                 array( 'User', 'makeGroupLinkWiki' ),
 397                                 User::getGroupsWithPermission( $this->permission )
 398                         );
 399
 400                         if ( $groups ) {
 401                                 $errors[] = array( 'badaccess-groups', $wgLang->commaList( $groups ), count( $groups ) );
 402                         } else {
 403                                 $errors[] = array( 'badaccess-group0' );
 404                         }
 405                 }
 406
 407                 $this->errors = $errors;
 408         }
 409
 410         function report() {
 411                 global $wgOut;
 412
 413                 $wgOut->showPermissionsErrorPage( $this->errors, $this->permission );
 414                 $wgOut->output();
 415         }
 416 }
 417
 418 /**
 419  * Show an error when the wiki is locked/read-only and the user tries to do
 420  * something that requires write access.
 421  *
 422  * @since 1.18
 423  * @ingroup Exception
 424  */
 425 class ReadOnlyError extends ErrorPageError {
 426         public function __construct() {
 427                 parent::__construct(
 428                         'readonly',
 429                         'readonlytext',
 430                         wfReadOnlyReason()
 431                 );
 432         }
 433 }
 434
 435 /**
 436  * Show an error when the user hits a rate limit.
 437  *
 438  * @since 1.18
 439  * @ingroup Exception
 440  */
 441 class ThrottledError extends ErrorPageError {
 442         public function __construct() {
 443                 parent::__construct(
 444                         'actionthrottled',
 445                         'actionthrottledtext'
 446                 );
 447         }
 448
 449         public function report() {
 450                 global $wgOut;
 451                 $wgOut->setStatusCode( 503 );
 452                 parent::report();
 453         }
 454 }
 455
 456 /**
 457  * Show an error when the user tries to do something whilst blocked.
 458  *
 459  * @since 1.18
 460  * @ingroup Exception
 461  */
 462 class UserBlockedError extends ErrorPageError {
 463         public function __construct( Block $block ) {
 464                 global $wgLang, $wgRequest;
 465
 466                 $blocker = $block->getBlocker();
 467                 if ( $blocker instanceof User ) { // local user
 468                         $blockerUserpage = $block->getBlocker()->getUserPage();
 469                         $link = "[[{$blockerUserpage->getPrefixedText()}|{$blockerUserpage->getText()}]]";
 470                 } else { // foreign user
 471                         $link = $blocker;
 472                 }
 473
 474                 $reason = $block->mReason;
 475                 if( $reason == '' ) {
 476                         $reason = wfMessage( 'blockednoreason' )->text();
 477                 }
 478
 479                 /* $ip returns who *is* being blocked, $intended contains who was meant to be blocked.
 480                  * This could be a username, an IP range, or a single IP. */
 481                 $intended = $block->getTarget();
 482
 483                 parent::__construct(
 484                         'blockedtitle',
 485                         $block->mAuto ? 'autoblockedtext' : 'blockedtext',
 486                         array(
 487                                 $link,
 488                                 $reason,
 489                                 $wgRequest->getIP(),
 490                                 $block->getByName(),
 491                                 $block->getId(),
 492                                 $wgLang->formatExpiry( $block->mExpiry ),
 493                                 $intended,
 494                                 $wgLang->timeanddate( wfTimestamp( TS_MW, $block->mTimestamp ), true )
 495                         )
 496                 );
 497         }
 498 }
 499
 500 /**
 501  * Shows a generic "user is not logged in" error page.
 502  *
 503  * This is essentially an ErrorPageError exception which by default uses the
 504  * 'exception-nologin' as a title and 'exception-nologin-text' for the message.
 505  * @see bug 37627
 506  * @since 1.20
 507  *
 508  * @par Example:
 509  * @code
 510  * if( $user->isAnon() ) {
 511  *      throw new UserNotLoggedIn();
 512  * }
 513  * @endcode
 514  *
 515  * Note the parameter order differs from ErrorPageError, this allows you to
 516  * simply specify a reason without overriding the default title.
 517  *
 518  * @par Example:
 519  * @code
 520  * if( $user->isAnon() ) {
 521  *      throw new UserNotLoggedIn( 'action-require-loggedin' );
 522  * }
 523  * @endcode
 524  *
 525  * @ingroup Exception
 526  */
 527 class UserNotLoggedIn extends ErrorPageError {
 528
 529         /**
 530          * @param $reasonMsg A message key containing the reason for the error.
 531          *        Optional, default: 'exception-nologin-text'
 532          * @param $titleMsg A message key to set the page title.
 533          *        Optional, default: 'exception-nologin'
 534          * @param $params Parameters to wfMessage().
 535          *        Optional, default: null
 536          */
 537         public function __construct(
 538                 $reasonMsg = 'exception-nologin-text',
 539                 $titleMsg  = 'exception-nologin',
 540                 $params = null
 541         ) {
 542                 parent::__construct( $titleMsg, $reasonMsg, $params );
 543         }
 544 }
 545
 546 /**
 547  * Show an error that looks like an HTTP server error.
 548  * Replacement for wfHttpError().
 549  *
 550  * @since 1.19
 551  * @ingroup Exception
 552  */
 553 class HttpError extends MWException {
 554         private $httpCode, $header, $content;
 555
 556         /**
 557          * Constructor
 558          *
 559          * @param $httpCode Integer: HTTP status code to send to the client
 560          * @param $content String|Message: content of the message
 561          * @param $header String|Message: content of the header (\<title\> and \<h1\>)
 562          */
 563         public function __construct( $httpCode, $content, $header = null ) {
 564                 parent::__construct( $content );
 565                 $this->httpCode = (int)$httpCode;
 566                 $this->header = $header;
 567                 $this->content = $content;
 568         }
 569
 570         /**
 571          * Returns the HTTP status code supplied to the constructor.
 572          *
 573          * @return int
 574          */
 575         public function getStatusCode() {
 576                 $this->httpCode;
 577         }
 578
 579         /**
 580          * Report the HTTP error.
 581          * Sends the appropriate HTTP status code and outputs an
 582          * HTML page with an error message.
 583          */
 584         public function report() {
 585                 $httpMessage = HttpStatus::getMessage( $this->httpCode );
 586
 587                 header( "Status: {$this->httpCode} {$httpMessage}", true, $this->httpCode );
 588                 header( 'Content-type: text/html; charset=utf-8' );
 589
 590                 print $this->getHTML();
 591         }
 592
 593         /**
 594          * Returns HTML for reporting the HTTP error.
 595          * This will be a minimal but complete HTML document.
 596          *
 597          * @return string HTML
 598          */
 599         public function getHTML() {
 600                 if ( $this->header === null ) {
 601                         $header = HttpStatus::getMessage( $this->httpCode );
 602                 } elseif ( $this->header instanceof Message ) {
 603                         $header = $this->header->escaped();
 604                 } else {
 605                         $header = htmlspecialchars( $this->header );
 606                 }
 607
 608                 if ( $this->content instanceof Message ) {
 609                         $content = $this->content->escaped();
 610                 } else {
 611                         $content = htmlspecialchars( $this->content );
 612                 }
 613
 614                 return "<!DOCTYPE html>\n".
 615                         "<html><head><title>$header</title></head>\n" .
 616                         "<body><h1>$header</h1><p>$content</p></body></html>\n";
 617         }
 618 }
 619
 620 /**
 621  * Handler class for MWExceptions
 622  * @ingroup Exception
 623  */
 624 class MWExceptionHandler {
 625         /**
 626          * Install an exception handler for MediaWiki exception types.
 627          */
 628         public static function installHandler() {
 629                 set_exception_handler( array( 'MWExceptionHandler', 'handle' ) );
 630         }
 631
 632         /**
 633          * Report an exception to the user
 634          */
 635         protected static function report( Exception $e ) {
 636                 global $wgShowExceptionDetails;
 637
 638                 $cmdLine = MWException::isCommandLine();
 639
 640                 if ( $e instanceof MWException ) {
 641                         try {
 642                                 // Try and show the exception prettily, with the normal skin infrastructure
 643                                 $e->report();
 644                         } catch ( Exception $e2 ) {
 645                                 // Exception occurred from within exception handler
 646                                 // Show a simpler error message for the original exception,
 647                                 // don't try to invoke report()
 648                                 $message = "MediaWiki internal error.\n\n";
 649
 650                                 if ( $wgShowExceptionDetails ) {
 651                                         $message .= 'Original exception: ' . $e->__toString() . "\n\n" .
 652                                                 'Exception caught inside exception handler: ' . $e2->__toString();
 653                                 } else {
 654                                         $message .= "Exception caught inside exception handler.\n\n" .
 655                                                 "Set \$wgShowExceptionDetails = true; at the bottom of LocalSettings.php " .
 656                                                 "to show detailed debugging information.";
 657                                 }
 658
 659                                 $message .= "\n";
 660
 661                                 if ( $cmdLine ) {
 662                                         self::printError( $message );
 663                                 } else {
 664                                         echo nl2br( htmlspecialchars( $message ) ) . "\n";
 665                                 }
 666                         }
 667                 } else {
 668                         $message = "Unexpected non-MediaWiki exception encountered, of type \"" . get_class( $e ) . "\"\n" .
 669                                 $e->__toString() . "\n";
 670
 671                         if ( $wgShowExceptionDetails ) {
 672                                 $message .= "\n" . $e->getTraceAsString() . "\n";
 673                         }
 674
 675                         if ( $cmdLine ) {
 676                                 self::printError( $message );
 677                         } else {
 678                                 echo nl2br( htmlspecialchars( $message ) ) . "\n";
 679                         }
 680                 }
 681         }
 682
 683         /**
 684          * Print a message, if possible to STDERR.
 685          * Use this in command line mode only (see isCommandLine)
 686          *
 687          * @param $message string Failure text
 688          */
 689         public static function printError( $message ) {
 690                 # NOTE: STDERR may not be available, especially if php-cgi is used from the command line (bug #15602).
 691                 #      Try to produce meaningful output anyway. Using echo may corrupt output to STDOUT though.
 692                 if ( defined( 'STDERR' ) ) {
 693                         fwrite( STDERR, $message );
 694                 } else {
 695                         echo( $message );
 696                 }
 697         }
 698
 699         /**
 700          * Exception handler which simulates the appropriate catch() handling:
 701          *
 702          *   try {
 703          *       ...
 704          *   } catch ( MWException $e ) {
 705          *       $e->report();
 706          *   } catch ( Exception $e ) {
 707          *       echo $e->__toString();
 708          *   }
 709          */
 710         public static function handle( $e ) {
 711                 global $wgFullyInitialised;
 712
 713                 self::report( $e );
 714
 715                 // Final cleanup
 716                 if ( $wgFullyInitialised ) {
 717                         try {
 718                                 wfLogProfilingData(); // uses $wgRequest, hence the $wgFullyInitialised condition
 719                         } catch ( Exception $e ) {}
 720                 }
 721
 722                 // Exit value should be nonzero for the benefit of shell jobs
 723                 exit( 1 );
 724         }
 725 }