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, $wgMimeType;
 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                         header( "Content-Type: $wgMimeType; charset=utf-8", 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 string|Message $title Message key (string) for page title, or a Message object
 324          * @param string|Message $msg Message key (string) for error text, or a Message object
 325          * @param array $params 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                 // Bug 44111: Messages in the log files should be in English and not
 333                 // customized by the local wiki. So get the default English version for
 334                 // passing to the parent constructor. Our overridden report() below
 335                 // makes sure that the page shown to the user is not forced to English.
 336                 if ( $msg instanceof Message ) {
 337                         $enMsg = clone( $msg );
 338                 } else {
 339                         $enMsg = wfMessage( $msg, $params );
 340                 }
 341                 $enMsg->inLanguage( 'en' )->useDatabase( false );
 342                 parent::__construct( $enMsg->text() );
 343         }
 344
 345         function report() {
 346                 global $wgOut;
 347
 348                 $wgOut->showErrorPage( $this->title, $this->msg, $this->params );
 349                 $wgOut->output();
 350         }
 351 }
 352
 353 /**
 354  * Show an error page on a badtitle.
 355  * Similar to ErrorPage, but emit a 400 HTTP error code to let mobile
 356  * browser it is not really a valid content.
 357  *
 358  * @since 1.19
 359  * @ingroup Exception
 360  */
 361 class BadTitleError extends ErrorPageError {
 362         /**
 363          * @param string|Message $msg A message key (default: 'badtitletext')
 364          * @param array $params parameter to wfMessage()
 365          */
 366         function __construct( $msg = 'badtitletext', $params = null ) {
 367                 parent::__construct( 'badtitle', $msg, $params );
 368         }
 369
 370         /**
 371          * Just like ErrorPageError::report() but additionally set
 372          * a 400 HTTP status code (bug 33646).
 373          */
 374         function report() {
 375                 global $wgOut;
 376
 377                 // bug 33646: a badtitle error page need to return an error code
 378                 // to let mobile browser now that it is not a normal page.
 379                 $wgOut->setStatusCode( 400 );
 380                 parent::report();
 381         }
 382
 383 }
 384
 385 /**
 386  * Show an error when a user tries to do something they do not have the necessary
 387  * permissions for.
 388  *
 389  * @since 1.18
 390  * @ingroup Exception
 391  */
 392 class PermissionsError extends ErrorPageError {
 393         public $permission, $errors;
 394
 395         function __construct( $permission, $errors = array() ) {
 396                 global $wgLang;
 397
 398                 $this->permission = $permission;
 399
 400                 if ( !count( $errors ) ) {
 401                         $groups = array_map(
 402                                 array( 'User', 'makeGroupLinkWiki' ),
 403                                 User::getGroupsWithPermission( $this->permission )
 404                         );
 405
 406                         if ( $groups ) {
 407                                 $errors[] = array( 'badaccess-groups', $wgLang->commaList( $groups ), count( $groups ) );
 408                         } else {
 409                                 $errors[] = array( 'badaccess-group0' );
 410                         }
 411                 }
 412
 413                 $this->errors = $errors;
 414         }
 415
 416         function report() {
 417                 global $wgOut;
 418
 419                 $wgOut->showPermissionsErrorPage( $this->errors, $this->permission );
 420                 $wgOut->output();
 421         }
 422 }
 423
 424 /**
 425  * Show an error when the wiki is locked/read-only and the user tries to do
 426  * something that requires write access.
 427  *
 428  * @since 1.18
 429  * @ingroup Exception
 430  */
 431 class ReadOnlyError extends ErrorPageError {
 432         public function __construct() {
 433                 parent::__construct(
 434                         'readonly',
 435                         'readonlytext',
 436                         wfReadOnlyReason()
 437                 );
 438         }
 439 }
 440
 441 /**
 442  * Show an error when the user hits a rate limit.
 443  *
 444  * @since 1.18
 445  * @ingroup Exception
 446  */
 447 class ThrottledError extends ErrorPageError {
 448         public function __construct() {
 449                 parent::__construct(
 450                         'actionthrottled',
 451                         'actionthrottledtext'
 452                 );
 453         }
 454
 455         public function report() {
 456                 global $wgOut;
 457                 $wgOut->setStatusCode( 503 );
 458                 parent::report();
 459         }
 460 }
 461
 462 /**
 463  * Show an error when the user tries to do something whilst blocked.
 464  *
 465  * @since 1.18
 466  * @ingroup Exception
 467  */
 468 class UserBlockedError extends ErrorPageError {
 469         public function __construct( Block $block ) {
 470                 // @todo FIXME: Implement a more proper way to get context here.
 471                 $params = $block->getPermissionsError( RequestContext::getMain() );
 472                 parent::__construct( 'blockedtitle', array_shift( $params ), $params );
 473         }
 474 }
 475
 476 /**
 477  * Shows a generic "user is not logged in" error page.
 478  *
 479  * This is essentially an ErrorPageError exception which by default uses the
 480  * 'exception-nologin' as a title and 'exception-nologin-text' for the message.
 481  * @see bug 37627
 482  * @since 1.20
 483  *
 484  * @par Example:
 485  * @code
 486  * if( $user->isAnon() ) {
 487  *      throw new UserNotLoggedIn();
 488  * }
 489  * @endcode
 490  *
 491  * Note the parameter order differs from ErrorPageError, this allows you to
 492  * simply specify a reason without overriding the default title.
 493  *
 494  * @par Example:
 495  * @code
 496  * if( $user->isAnon() ) {
 497  *      throw new UserNotLoggedIn( 'action-require-loggedin' );
 498  * }
 499  * @endcode
 500  *
 501  * @ingroup Exception
 502  */
 503 class UserNotLoggedIn extends ErrorPageError {
 504
 505         /**
 506          * @param $reasonMsg A message key containing the reason for the error.
 507          *        Optional, default: 'exception-nologin-text'
 508          * @param $titleMsg A message key to set the page title.
 509          *        Optional, default: 'exception-nologin'
 510          * @param $params Parameters to wfMessage().
 511          *        Optional, default: null
 512          */
 513         public function __construct(
 514                 $reasonMsg = 'exception-nologin-text',
 515                 $titleMsg = 'exception-nologin',
 516                 $params = null
 517         ) {
 518                 parent::__construct( $titleMsg, $reasonMsg, $params );
 519         }
 520 }
 521
 522 /**
 523  * Show an error that looks like an HTTP server error.
 524  * Replacement for wfHttpError().
 525  *
 526  * @since 1.19
 527  * @ingroup Exception
 528  */
 529 class HttpError extends MWException {
 530         private $httpCode, $header, $content;
 531
 532         /**
 533          * Constructor
 534          *
 535          * @param $httpCode Integer: HTTP status code to send to the client
 536          * @param string|Message $content content of the message
 537          * @param string|Message $header content of the header (\<title\> and \<h1\>)
 538          */
 539         public function __construct( $httpCode, $content, $header = null ) {
 540                 parent::__construct( $content );
 541                 $this->httpCode = (int)$httpCode;
 542                 $this->header = $header;
 543                 $this->content = $content;
 544         }
 545
 546         /**
 547          * Returns the HTTP status code supplied to the constructor.
 548          *
 549          * @return int
 550          */
 551         public function getStatusCode() {
 552                 return $this->httpCode;
 553         }
 554
 555         /**
 556          * Report the HTTP error.
 557          * Sends the appropriate HTTP status code and outputs an
 558          * HTML page with an error message.
 559          */
 560         public function report() {
 561                 $httpMessage = HttpStatus::getMessage( $this->httpCode );
 562
 563                 header( "Status: {$this->httpCode} {$httpMessage}", true, $this->httpCode );
 564                 header( 'Content-type: text/html; charset=utf-8' );
 565
 566                 print $this->getHTML();
 567         }
 568
 569         /**
 570          * Returns HTML for reporting the HTTP error.
 571          * This will be a minimal but complete HTML document.
 572          *
 573          * @return string HTML
 574          */
 575         public function getHTML() {
 576                 if ( $this->header === null ) {
 577                         $header = HttpStatus::getMessage( $this->httpCode );
 578                 } elseif ( $this->header instanceof Message ) {
 579                         $header = $this->header->escaped();
 580                 } else {
 581                         $header = htmlspecialchars( $this->header );
 582                 }
 583
 584                 if ( $this->content instanceof Message ) {
 585                         $content = $this->content->escaped();
 586                 } else {
 587                         $content = htmlspecialchars( $this->content );
 588                 }
 589
 590                 return "<!DOCTYPE html>\n" .
 591                         "<html><head><title>$header</title></head>\n" .
 592                         "<body><h1>$header</h1><p>$content</p></body></html>\n";
 593         }
 594 }
 595
 596 /**
 597  * Handler class for MWExceptions
 598  * @ingroup Exception
 599  */
 600 class MWExceptionHandler {
 601         /**
 602          * Install an exception handler for MediaWiki exception types.
 603          */
 604         public static function installHandler() {
 605                 set_exception_handler( array( 'MWExceptionHandler', 'handle' ) );
 606         }
 607
 608         /**
 609          * Report an exception to the user
 610          */
 611         protected static function report( Exception $e ) {
 612                 global $wgShowExceptionDetails;
 613
 614                 $cmdLine = MWException::isCommandLine();
 615
 616                 if ( $e instanceof MWException ) {
 617                         try {
 618                                 // Try and show the exception prettily, with the normal skin infrastructure
 619                                 $e->report();
 620                         } catch ( Exception $e2 ) {
 621                                 // Exception occurred from within exception handler
 622                                 // Show a simpler error message for the original exception,
 623                                 // don't try to invoke report()
 624                                 $message = "MediaWiki internal error.\n\n";
 625
 626                                 if ( $wgShowExceptionDetails ) {
 627                                         $message .= 'Original exception: ' . $e->__toString() . "\n\n" .
 628                                                 'Exception caught inside exception handler: ' . $e2->__toString();
 629                                 } else {
 630                                         $message .= "Exception caught inside exception handler.\n\n" .
 631                                                 "Set \$wgShowExceptionDetails = true; at the bottom of LocalSettings.php " .
 632                                                 "to show detailed debugging information.";
 633                                 }
 634
 635                                 $message .= "\n";
 636
 637                                 if ( $cmdLine ) {
 638                                         self::printError( $message );
 639                                 } else {
 640                                         echo nl2br( htmlspecialchars( $message ) ) . "\n";
 641                                 }
 642                         }
 643                 } else {
 644                         $message = "Unexpected non-MediaWiki exception encountered, of type \"" . get_class( $e ) . "\"\n" .
 645                                 $e->__toString() . "\n";
 646
 647                         if ( $wgShowExceptionDetails ) {
 648                                 $message .= "\n" . $e->getTraceAsString() . "\n";
 649                         }
 650
 651                         if ( $cmdLine ) {
 652                                 self::printError( $message );
 653                         } else {
 654                                 echo nl2br( htmlspecialchars( $message ) ) . "\n";
 655                         }
 656                 }
 657         }
 658
 659         /**
 660          * Print a message, if possible to STDERR.
 661          * Use this in command line mode only (see isCommandLine)
 662          *
 663          * @param string $message Failure text
 664          */
 665         public static function printError( $message ) {
 666                 # NOTE: STDERR may not be available, especially if php-cgi is used from the command line (bug #15602).
 667                 #      Try to produce meaningful output anyway. Using echo may corrupt output to STDOUT though.
 668                 if ( defined( 'STDERR' ) ) {
 669                         fwrite( STDERR, $message );
 670                 } else {
 671                         echo $message;
 672                 }
 673         }
 674
 675         /**
 676          * Exception handler which simulates the appropriate catch() handling:
 677          *
 678          *   try {
 679          *       ...
 680          *   } catch ( MWException $e ) {
 681          *       $e->report();
 682          *   } catch ( Exception $e ) {
 683          *       echo $e->__toString();
 684          *   }
 685          */
 686         public static function handle( $e ) {
 687                 global $wgFullyInitialised;
 688
 689                 self::report( $e );
 690
 691                 // Final cleanup
 692                 if ( $wgFullyInitialised ) {
 693                         try {
 694                                 // uses $wgRequest, hence the $wgFullyInitialised condition
 695                                 wfLogProfilingData();
 696                         } catch ( Exception $e ) {
 697                         }
 698                 }
 699
 700                 // Exit value should be nonzero for the benefit of shell jobs
 701                 exit( 1 );
 702         }
 703 }