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