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 string $name class name of the exception
  68          * @param array $args 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 string $key message name
 103          * @param string $fallback 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 "<div class=\"errorbox\">" .
 134                                 '[' . $this->getLogId() . '] ' .
 135                                 gmdate( 'Y-m-d H:i:s' ) .
 136                                 ": Fatal exception of type " . get_class( $this ) . "</div>\n" .
 137                                 "<!-- Set \$wgShowExceptionDetails = true; " .
 138                                 "at the bottom of LocalSettings.php to show detailed " .
 139                                 "debugging information. -->";
 140                 }
 141         }
 142
 143         /**
 144          * Get the text to display when reporting the error on the command line.
 145          * If $wgShowExceptionDetails is true, return a text message with a
 146          * backtrace to the error.
 147          *
 148          * @return string
 149          */
 150         function getText() {
 151                 global $wgShowExceptionDetails;
 152
 153                 if ( $wgShowExceptionDetails ) {
 154                         return $this->getMessage() .
 155                                 "\nBacktrace:\n" . $this->getTraceAsString() . "\n";
 156                 } else {
 157                         return "Set \$wgShowExceptionDetails = true; " .
 158                                 "in LocalSettings.php to show detailed debugging information.\n";
 159                 }
 160         }
 161
 162         /**
 163          * Return the title of the page when reporting this error in a HTTP response.
 164          *
 165          * @return string
 166          */
 167         function getPageTitle() {
 168                 return $this->msg( 'internalerror', "Internal error" );
 169         }
 170
 171         /**
 172          * Get a random ID for this error.
 173          * This allows to link the exception to its corresponding log entry when
 174          * $wgShowExceptionDetails is set to false.
 175          *
 176          * @return string
 177          */
 178         function getLogId() {
 179                 if ( $this->logId === null ) {
 180                         $this->logId = wfRandomString( 8 );
 181                 }
 182                 return $this->logId;
 183         }
 184
 185         /**
 186          * Return the requested URL and point to file and line number from which the
 187          * exception occurred
 188          *
 189          * @return string
 190          */
 191         function getLogMessage() {
 192                 global $wgRequest;
 193
 194                 $id = $this->getLogId();
 195                 $file = $this->getFile();
 196                 $line = $this->getLine();
 197                 $message = $this->getMessage();
 198
 199                 if ( isset( $wgRequest ) && !$wgRequest instanceof FauxRequest ) {
 200                         $url = $wgRequest->getRequestURL();
 201                         if ( !$url ) {
 202                                 $url = '[no URL]';
 203                         }
 204                 } else {
 205                         $url = '[no req]';
 206                 }
 207
 208                 return "[$id] $url   Exception from line $line of $file: $message";
 209         }
 210
 211         /**
 212          * Output the exception report using HTML.
 213          */
 214         function reportHTML() {
 215                 global $wgOut;
 216                 if ( $this->useOutputPage() ) {
 217                         $wgOut->prepareErrorPage( $this->getPageTitle() );
 218
 219                         $hookResult = $this->runHooks( get_class( $this ) );
 220                         if ( $hookResult ) {
 221                                 $wgOut->addHTML( $hookResult );
 222                         } else {
 223                                 $wgOut->addHTML( $this->getHTML() );
 224                         }
 225
 226                         $wgOut->output();
 227                 } else {
 228                         header( "Content-Type: text/html; charset=utf-8" );
 229                         echo "<!doctype html>\n" .
 230                                 '<html><head>' .
 231                                 '<title>' . htmlspecialchars( $this->getPageTitle() ) . '</title>' .
 232                                 "</head><body>\n";
 233
 234                         $hookResult = $this->runHooks( get_class( $this ) . "Raw" );
 235                         if ( $hookResult ) {
 236                                 echo $hookResult;
 237                         } else {
 238                                 echo $this->getHTML();
 239                         }
 240
 241                         echo "</body></html>\n";
 242                 }
 243         }
 244
 245         /**
 246          * Output a report about the exception and takes care of formatting.
 247          * It will be either HTML or plain text based on isCommandLine().
 248          */
 249         function report() {
 250                 global $wgLogExceptionBacktrace;
 251                 $log = $this->getLogMessage();
 252
 253                 if ( $log ) {
 254                         if ( $wgLogExceptionBacktrace ) {
 255                                 wfDebugLog( 'exception', $log . "\n" . $this->getTraceAsString() . "\n" );
 256                         } else {
 257                                 wfDebugLog( 'exception', $log );
 258                         }
 259                 }
 260
 261                 if ( defined( 'MW_API' ) ) {
 262                         // Unhandled API exception, we can't be sure that format printer is alive
 263                         header( 'MediaWiki-API-Error: internal_api_error_' . get_class( $this ) );
 264                         wfHttpError( 500, 'Internal Server Error', $this->getText() );
 265                 } elseif ( self::isCommandLine() ) {
 266                         MWExceptionHandler::printError( $this->getText() );
 267                 } else {
 268                         header( "HTTP/1.1 500 MediaWiki exception" );
 269                         header( "Status: 500 MediaWiki exception", true );
 270
 271                         $this->reportHTML();
 272                 }
 273         }
 274
 275         /**
 276          * Check whether we are in command line mode or not to report the exception
 277          * in the correct format.
 278          *
 279          * @return bool
 280          */
 281         static function isCommandLine() {
 282                 return !empty( $GLOBALS['wgCommandLineMode'] );
 283         }
 284 }
 285
 286 /**
 287  * Exception class which takes an HTML error message, and does not
 288  * produce a backtrace. Replacement for OutputPage::fatalError().
 289  *
 290  * @since 1.7
 291  * @ingroup Exception
 292  */
 293 class FatalError extends MWException {
 294
 295         /**
 296          * @return string
 297          */
 298         function getHTML() {
 299                 return $this->getMessage();
 300         }
 301
 302         /**
 303          * @return string
 304          */
 305         function getText() {
 306                 return $this->getMessage();
 307         }
 308 }
 309
 310 /**
 311  * An error page which can definitely be safely rendered using the OutputPage.
 312  *
 313  * @since 1.7
 314  * @ingroup Exception
 315  */
 316 class ErrorPageError extends MWException {
 317         public $title, $msg, $params;
 318
 319         /**
 320          * Note: these arguments are keys into wfMessage(), not text!
 321          *
 322          * @param string|Message $title Message key (string) for page title, or a Message object
 323          * @param string|Message $msg Message key (string) for error text, or a Message object
 324          * @param array $params with parameters to wfMessage()
 325          */
 326         function __construct( $title, $msg, $params = null ) {
 327                 $this->title = $title;
 328                 $this->msg = $msg;
 329                 $this->params = $params;
 330
 331                 // Bug 44111: Messages in the log files should be in English and not
 332                 // customized by the local wiki. So get the default English version for
 333                 // passing to the parent constructor. Our overridden report() below
 334                 // makes sure that the page shown to the user is not forced to English.
 335                 if( $msg instanceof Message ) {
 336                         $enMsg = clone( $msg );
 337                 } else {
 338                         $enMsg = wfMessage( $msg, $params );
 339                 }
 340                 $enMsg->inLanguage( 'en' )->useDatabase( false );
 341                 parent::__construct( $enMsg->text() );
 342         }
 343
 344         function report() {
 345                 global $wgOut;
 346
 347                 $wgOut->showErrorPage( $this->title, $this->msg, $this->params );
 348                 $wgOut->output();
 349         }
 350 }
 351
 352 /**
 353  * Show an error page on a badtitle.
 354  * Similar to ErrorPage, but emit a 400 HTTP error code to let mobile
 355  * browser it is not really a valid content.
 356  *
 357  * @since 1.19
 358  * @ingroup Exception
 359  */
 360 class BadTitleError extends ErrorPageError {
 361         /**
 362          * @param string|Message $msg A message key (default: 'badtitletext')
 363          * @param array $params parameter to wfMessage()
 364          */
 365         function __construct( $msg = 'badtitletext', $params = null ) {
 366                 parent::__construct( 'badtitle', $msg, $params );
 367         }
 368
 369         /**
 370          * Just like ErrorPageError::report() but additionally set
 371          * a 400 HTTP status code (bug 33646).
 372          */
 373         function report() {
 374                 global $wgOut;
 375
 376                 // bug 33646: a badtitle error page need to return an error code
 377                 // to let mobile browser now that it is not a normal page.
 378                 $wgOut->setStatusCode( 400 );
 379                 parent::report();
 380         }
 381
 382 }
 383
 384 /**
 385  * Show an error when a user tries to do something they do not have the necessary
 386  * permissions for.
 387  *
 388  * @since 1.18
 389  * @ingroup Exception
 390  */
 391 class PermissionsError extends ErrorPageError {
 392         public $permission, $errors;
 393
 394         function __construct( $permission, $errors = array() ) {
 395                 global $wgLang;
 396
 397                 $this->permission = $permission;
 398
 399                 if ( !count( $errors ) ) {
 400                         $groups = array_map(
 401                                 array( 'User', 'makeGroupLinkWiki' ),
 402                                 User::getGroupsWithPermission( $this->permission )
 403                         );
 404
 405                         if ( $groups ) {
 406                                 $errors[] = array( 'badaccess-groups', $wgLang->commaList( $groups ), count( $groups ) );
 407                         } else {
 408                                 $errors[] = array( 'badaccess-group0' );
 409                         }
 410                 }
 411
 412                 $this->errors = $errors;
 413         }
 414
 415         function report() {
 416                 global $wgOut;
 417
 418                 $wgOut->showPermissionsErrorPage( $this->errors, $this->permission );
 419                 $wgOut->output();
 420         }
 421 }
 422
 423 /**
 424  * Show an error when the wiki is locked/read-only and the user tries to do
 425  * something that requires write access.
 426  *
 427  * @since 1.18
 428  * @ingroup Exception
 429  */
 430 class ReadOnlyError extends ErrorPageError {
 431         public function __construct() {
 432                 parent::__construct(
 433                         'readonly',
 434                         'readonlytext',
 435                         wfReadOnlyReason()
 436                 );
 437         }
 438 }
 439
 440 /**
 441  * Show an error when the user hits a rate limit.
 442  *
 443  * @since 1.18
 444  * @ingroup Exception
 445  */
 446 class ThrottledError extends ErrorPageError {
 447         public function __construct() {
 448                 parent::__construct(
 449                         'actionthrottled',
 450                         'actionthrottledtext'
 451                 );
 452         }
 453
 454         public function report() {
 455                 global $wgOut;
 456                 $wgOut->setStatusCode( 503 );
 457                 parent::report();
 458         }
 459 }
 460
 461 /**
 462  * Show an error when the user tries to do something whilst blocked.
 463  *
 464  * @since 1.18
 465  * @ingroup Exception
 466  */
 467 class UserBlockedError extends ErrorPageError {
 468         public function __construct( Block $block ) {
 469                 global $wgLang, $wgRequest;
 470
 471                 $blocker = $block->getBlocker();
 472                 if ( $blocker instanceof User ) { // local user
 473                         $blockerUserpage = $block->getBlocker()->getUserPage();
 474                         $link = "[[{$blockerUserpage->getPrefixedText()}|{$blockerUserpage->getText()}]]";
 475                 } else { // foreign user
 476                         $link = $blocker;
 477                 }
 478
 479                 $reason = $block->mReason;
 480                 if( $reason == '' ) {
 481                         $reason = wfMessage( 'blockednoreason' )->text();
 482                 }
 483
 484                 /* $ip returns who *is* being blocked, $intended contains who was meant to be blocked.
 485                  * This could be a username, an IP range, or a single IP. */
 486                 $intended = $block->getTarget();
 487
 488                 parent::__construct(
 489                         'blockedtitle',
 490                         $block->mAuto ? 'autoblockedtext' : 'blockedtext',
 491                         array(
 492                                 $link,
 493                                 $reason,
 494                                 $wgRequest->getIP(),
 495                                 $block->getByName(),
 496                                 $block->getId(),
 497                                 $wgLang->formatExpiry( $block->mExpiry ),
 498                                 $intended,
 499                                 $wgLang->timeanddate( wfTimestamp( TS_MW, $block->mTimestamp ), true )
 500                         )
 501                 );
 502         }
 503 }
 504
 505 /**
 506  * Shows a generic "user is not logged in" error page.
 507  *
 508  * This is essentially an ErrorPageError exception which by default uses the
 509  * 'exception-nologin' as a title and 'exception-nologin-text' for the message.
 510  * @see bug 37627
 511  * @since 1.20
 512  *
 513  * @par Example:
 514  * @code
 515  * if( $user->isAnon() ) {
 516  *      throw new UserNotLoggedIn();
 517  * }
 518  * @endcode
 519  *
 520  * Note the parameter order differs from ErrorPageError, this allows you to
 521  * simply specify a reason without overriding the default title.
 522  *
 523  * @par Example:
 524  * @code
 525  * if( $user->isAnon() ) {
 526  *      throw new UserNotLoggedIn( 'action-require-loggedin' );
 527  * }
 528  * @endcode
 529  *
 530  * @ingroup Exception
 531  */
 532 class UserNotLoggedIn extends ErrorPageError {
 533
 534         /**
 535          * @param $reasonMsg A message key containing the reason for the error.
 536          *        Optional, default: 'exception-nologin-text'
 537          * @param $titleMsg A message key to set the page title.
 538          *        Optional, default: 'exception-nologin'
 539          * @param $params Parameters to wfMessage().
 540          *        Optional, default: null
 541          */
 542         public function __construct(
 543                 $reasonMsg = 'exception-nologin-text',
 544                 $titleMsg = 'exception-nologin',
 545                 $params = null
 546         ) {
 547                 parent::__construct( $titleMsg, $reasonMsg, $params );
 548         }
 549 }
 550
 551 /**
 552  * Show an error that looks like an HTTP server error.
 553  * Replacement for wfHttpError().
 554  *
 555  * @since 1.19
 556  * @ingroup Exception
 557  */
 558 class HttpError extends MWException {
 559         private $httpCode, $header, $content;
 560
 561         /**
 562          * Constructor
 563          *
 564          * @param $httpCode Integer: HTTP status code to send to the client
 565          * @param string|Message $content content of the message
 566          * @param string|Message $header content of the header (\<title\> and \<h1\>)
 567          */
 568         public function __construct( $httpCode, $content, $header = null ) {
 569                 parent::__construct( $content );
 570                 $this->httpCode = (int)$httpCode;
 571                 $this->header = $header;
 572                 $this->content = $content;
 573         }
 574
 575         /**
 576          * Returns the HTTP status code supplied to the constructor.
 577          *
 578          * @return int
 579          */
 580         public function getStatusCode() {
 581                 return $this->httpCode;
 582         }
 583
 584         /**
 585          * Report the HTTP error.
 586          * Sends the appropriate HTTP status code and outputs an
 587          * HTML page with an error message.
 588          */
 589         public function report() {
 590                 $httpMessage = HttpStatus::getMessage( $this->httpCode );
 591
 592                 header( "Status: {$this->httpCode} {$httpMessage}", true, $this->httpCode );
 593                 header( 'Content-type: text/html; charset=utf-8' );
 594
 595                 print $this->getHTML();
 596         }
 597
 598         /**
 599          * Returns HTML for reporting the HTTP error.
 600          * This will be a minimal but complete HTML document.
 601          *
 602          * @return string HTML
 603          */
 604         public function getHTML() {
 605                 if ( $this->header === null ) {
 606                         $header = HttpStatus::getMessage( $this->httpCode );
 607                 } elseif ( $this->header instanceof Message ) {
 608                         $header = $this->header->escaped();
 609                 } else {
 610                         $header = htmlspecialchars( $this->header );
 611                 }
 612
 613                 if ( $this->content instanceof Message ) {
 614                         $content = $this->content->escaped();
 615                 } else {
 616                         $content = htmlspecialchars( $this->content );
 617                 }
 618
 619                 return "<!DOCTYPE html>\n".
 620                         "<html><head><title>$header</title></head>\n" .
 621                         "<body><h1>$header</h1><p>$content</p></body></html>\n";
 622         }
 623 }
 624
 625 /**
 626  * Handler class for MWExceptions
 627  * @ingroup Exception
 628  */
 629 class MWExceptionHandler {
 630         /**
 631          * Install an exception handler for MediaWiki exception types.
 632          */
 633         public static function installHandler() {
 634                 set_exception_handler( array( 'MWExceptionHandler', 'handle' ) );
 635         }
 636
 637         /**
 638          * Report an exception to the user
 639          */
 640         protected static function report( Exception $e ) {
 641                 global $wgShowExceptionDetails;
 642
 643                 $cmdLine = MWException::isCommandLine();
 644
 645                 if ( $e instanceof MWException ) {
 646                         try {
 647                                 // Try and show the exception prettily, with the normal skin infrastructure
 648                                 $e->report();
 649                         } catch ( Exception $e2 ) {
 650                                 // Exception occurred from within exception handler
 651                                 // Show a simpler error message for the original exception,
 652                                 // don't try to invoke report()
 653                                 $message = "MediaWiki internal error.\n\n";
 654
 655                                 if ( $wgShowExceptionDetails ) {
 656                                         $message .= 'Original exception: ' . $e->__toString() . "\n\n" .
 657                                                 'Exception caught inside exception handler: ' . $e2->__toString();
 658                                 } else {
 659                                         $message .= "Exception caught inside exception handler.\n\n" .
 660                                                 "Set \$wgShowExceptionDetails = true; at the bottom of LocalSettings.php " .
 661                                                 "to show detailed debugging information.";
 662                                 }
 663
 664                                 $message .= "\n";
 665
 666                                 if ( $cmdLine ) {
 667                                         self::printError( $message );
 668                                 } else {
 669                                         echo nl2br( htmlspecialchars( $message ) ) . "\n";
 670                                 }
 671                         }
 672                 } else {
 673                         $message = "Unexpected non-MediaWiki exception encountered, of type \"" . get_class( $e ) . "\"\n" .
 674                                 $e->__toString() . "\n";
 675
 676                         if ( $wgShowExceptionDetails ) {
 677                                 $message .= "\n" . $e->getTraceAsString() . "\n";
 678                         }
 679
 680                         if ( $cmdLine ) {
 681                                 self::printError( $message );
 682                         } else {
 683                                 echo nl2br( htmlspecialchars( $message ) ) . "\n";
 684                         }
 685                 }
 686         }
 687
 688         /**
 689          * Print a message, if possible to STDERR.
 690          * Use this in command line mode only (see isCommandLine)
 691          *
 692          * @param string $message Failure text
 693          */
 694         public static function printError( $message ) {
 695                 # NOTE: STDERR may not be available, especially if php-cgi is used from the command line (bug #15602).
 696                 #      Try to produce meaningful output anyway. Using echo may corrupt output to STDOUT though.
 697                 if ( defined( 'STDERR' ) ) {
 698                         fwrite( STDERR, $message );
 699                 } else {
 700                         echo( $message );
 701                 }
 702         }
 703
 704         /**
 705          * Exception handler which simulates the appropriate catch() handling:
 706          *
 707          *   try {
 708          *       ...
 709          *   } catch ( MWException $e ) {
 710          *       $e->report();
 711          *   } catch ( Exception $e ) {
 712          *       echo $e->__toString();
 713          *   }
 714          */
 715         public static function handle( $e ) {
 716                 global $wgFullyInitialised;
 717
 718                 self::report( $e );
 719
 720                 // Final cleanup
 721                 if ( $wgFullyInitialised ) {
 722                         try {
 723                                 wfLogProfilingData(); // uses $wgRequest, hence the $wgFullyInitialised condition
 724                         } catch ( Exception $e ) {}
 725                 }
 726
 727                 // Exit value should be nonzero for the benefit of shell jobs
 728                 exit( 1 );
 729         }
 730 }