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MWExceptionHandler.php
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1 <?php
25 
31  const CAUGHT_BY_HANDLER = 'mwe_handler'; // error reported by this exception handler
32  const CAUGHT_BY_OTHER = 'other'; // error reported by direct logException() call
33 
37  protected static $reservedMemory;
38 
55  protected static $fatalErrorTypes = [
56  E_ERROR,
57  E_PARSE,
58  E_CORE_ERROR,
59  E_COMPILE_ERROR,
60  E_USER_ERROR,
61 
62  // E.g. "Catchable fatal error: Argument X must be Y, null given"
63  E_RECOVERABLE_ERROR,
64 
65  // HHVM's FATAL_ERROR constant
66  16777217,
67  ];
71  protected static $handledFatalCallback = false;
72 
76  public static function installHandler() {
77  set_exception_handler( 'MWExceptionHandler::handleUncaughtException' );
78  set_error_handler( 'MWExceptionHandler::handleError' );
79 
80  // Reserve 16k of memory so we can report OOM fatals
81  self::$reservedMemory = str_repeat( ' ', 16384 );
82  register_shutdown_function( 'MWExceptionHandler::handleFatalError' );
83  }
84 
89  protected static function report( $e ) {
90  try {
91  // Try and show the exception prettily, with the normal skin infrastructure
92  if ( $e instanceof MWException ) {
93  // Delegate to MWException until all subclasses are handled by
94  // MWExceptionRenderer and MWException::report() has been
95  // removed.
96  $e->report();
97  } else {
99  }
100  } catch ( Exception $e2 ) {
101  // Exception occurred from within exception handler
102  // Show a simpler message for the original exception,
103  // don't try to invoke report()
105  }
106  }
107 
116  public static function rollbackMasterChangesAndLog( $e ) {
117  $services = MediaWikiServices::getInstance();
118  if ( !$services->isServiceDisabled( 'DBLoadBalancerFactory' ) ) {
119  // Rollback DBs to avoid transaction notices. This might fail
120  // to rollback some databases due to connection issues or exceptions.
121  // However, any sane DB driver will rollback implicitly anyway.
122  try {
123  $services->getDBLoadBalancerFactory()->rollbackMasterChanges( __METHOD__ );
124  } catch ( DBError $e2 ) {
125  // If the DB is unreacheable, rollback() will throw an error
126  // and the error report() method might need messages from the DB,
127  // which would result in an exception loop. PHP may escalate such
128  // errors to "Exception thrown without a stack frame" fatals, but
129  // it's better to be explicit here.
130  self::logException( $e2, self::CAUGHT_BY_HANDLER );
131  }
132  }
133 
134  self::logException( $e, self::CAUGHT_BY_HANDLER );
135  }
136 
143  public static function handleUncaughtException( $e ) {
144  self::handleException( $e );
145 
146  // Make sure we don't claim success on exit for CLI scripts (T177414)
147  if ( wfIsCLI() ) {
148  register_shutdown_function(
149  function () {
150  exit( 255 );
151  }
152  );
153  }
154  }
155 
170  public static function handleException( $e ) {
171  self::rollbackMasterChangesAndLog( $e );
172  self::report( $e );
173  }
174 
193  public static function handleError(
194  $level, $message, $file = null, $line = null
195  ) {
196  global $wgPropagateErrors;
197 
198  if ( in_array( $level, self::$fatalErrorTypes ) ) {
199  return self::handleFatalError( ...func_get_args() );
200  }
201 
202  // Map PHP error constant to a PSR-3 severity level.
203  // Avoid use of "DEBUG" or "INFO" levels, unless the
204  // error should evade error monitoring and alerts.
205  //
206  // To decide the log level, ask yourself: "Has the
207  // program's behaviour diverged from what the written
208  // code expected?"
209  //
210  // For example, use of a deprecated method or violating a strict standard
211  // has no impact on functional behaviour (Warning). On the other hand,
212  // accessing an undefined variable makes behaviour diverge from what the
213  // author intended/expected. PHP recovers from an undefined variables by
214  // yielding null and continuing execution, but it remains a change in
215  // behaviour given the null was not part of the code and is likely not
216  // accounted for.
217  switch ( $level ) {
218  case E_WARNING:
219  case E_CORE_WARNING:
220  case E_COMPILE_WARNING:
221  $levelName = 'Warning';
222  $severity = LogLevel::ERROR;
223  break;
224  case E_NOTICE:
225  $levelName = 'Notice';
226  $severity = LogLevel::ERROR;
227  break;
228  case E_USER_NOTICE:
229  // Used by wfWarn(), MWDebug::warning()
230  $levelName = 'Notice';
231  $severity = LogLevel::WARNING;
232  break;
233  case E_USER_WARNING:
234  // Used by wfWarn(), MWDebug::warning()
235  $levelName = 'Warning';
236  $severity = LogLevel::WARNING;
237  break;
238  case E_STRICT:
239  $levelName = 'Strict Standards';
240  $severity = LogLevel::WARNING;
241  break;
242  case E_DEPRECATED:
243  case E_USER_DEPRECATED:
244  $levelName = 'Deprecated';
245  $severity = LogLevel::WARNING;
246  break;
247  default:
248  $levelName = 'Unknown error';
249  $severity = LogLevel::ERROR;
250  break;
251  }
252 
253  $e = new ErrorException( "PHP $levelName: $message", 0, $level, $file, $line );
254  self::logError( $e, 'error', $severity );
255 
256  // If $wgPropagateErrors is true return false so PHP shows/logs the error normally.
257  // Ignore $wgPropagateErrors if track_errors is set
258  // (which means someone is counting on regular PHP error handling behavior).
259  return !( $wgPropagateErrors || ini_get( 'track_errors' ) );
260  }
261 
283  public static function handleFatalError(
284  $level = null, $message = null, $file = null, $line = null,
285  $context = null, $trace = null
286  ) {
287  // Free reserved memory so that we have space to process OOM
288  // errors
289  self::$reservedMemory = null;
290 
291  if ( $level === null ) {
292  // Called as a shutdown handler, get data from error_get_last()
293  if ( static::$handledFatalCallback ) {
294  // Already called once (probably as an error handler callback
295  // under HHVM) so don't log again.
296  return false;
297  }
298 
299  $lastError = error_get_last();
300  if ( $lastError !== null ) {
301  $level = $lastError['type'];
302  $message = $lastError['message'];
303  $file = $lastError['file'];
304  $line = $lastError['line'];
305  } else {
306  $level = 0;
307  $message = '';
308  }
309  }
310 
311  if ( !in_array( $level, self::$fatalErrorTypes ) ) {
312  // Only interested in fatal errors, others should have been
313  // handled by MWExceptionHandler::handleError
314  return false;
315  }
316 
318  $msgParts = [
319  '[{exception_id}] {exception_url} PHP Fatal Error',
320  ( $line || $file ) ? ' from' : '',
321  $line ? " line $line" : '',
322  ( $line && $file ) ? ' of' : '',
323  $file ? " $file" : '',
324  ": $message",
325  ];
326  $msg = implode( '', $msgParts );
327 
328  // Look at message to see if this is a class not found failure
329  // HHVM: Class undefined: foo
330  // PHP5: Class 'foo' not found
331  if ( preg_match( "/Class (undefined: \w+|'\w+' not found)/", $message ) ) {
332  // phpcs:disable Generic.Files.LineLength
333  $msg = <<<TXT
334 {$msg}
335 
336 MediaWiki or an installed extension requires this class but it is not embedded directly in MediaWiki's git repository and must be installed separately by the end user.
337 
338 Please see <a href="https://www.mediawiki.org/wiki/Download_from_Git#Fetch_external_libraries">mediawiki.org</a> for help on installing the required components.
339 TXT;
340  // phpcs:enable
341  }
342 
343  // We can't just create an exception and log it as it is likely that
344  // the interpreter has unwound the stack already. If that is true the
345  // stacktrace we would get would be functionally empty. If however we
346  // have been called as an error handler callback *and* HHVM is in use
347  // we will have been provided with a useful stacktrace that we can
348  // log.
349  $trace = $trace ?: debug_backtrace();
350  $logger = LoggerFactory::getInstance( 'fatal' );
351  $logger->error( $msg, [
352  'fatal_exception' => [
353  'class' => ErrorException::class,
354  'message' => "PHP Fatal Error: {$message}",
355  'code' => $level,
356  'file' => $file,
357  'line' => $line,
358  'trace' => self::prettyPrintTrace( self::redactTrace( $trace ) ),
359  ],
360  'exception_id' => WebRequest::getRequestId(),
361  'exception_url' => $url,
362  'caught_by' => self::CAUGHT_BY_HANDLER
363  ] );
364 
365  // Remember call so we don't double process via HHVM's fatal
366  // notifications and the shutdown hook behavior
367  static::$handledFatalCallback = true;
368  return false;
369  }
370 
381  public static function getRedactedTraceAsString( $e ) {
382  return self::prettyPrintTrace( self::getRedactedTrace( $e ) );
383  }
384 
393  public static function prettyPrintTrace( array $trace, $pad = '' ) {
394  $text = '';
395 
396  $level = 0;
397  foreach ( $trace as $level => $frame ) {
398  if ( isset( $frame['file'] ) && isset( $frame['line'] ) ) {
399  $text .= "{$pad}#{$level} {$frame['file']}({$frame['line']}): ";
400  } else {
401  // 'file' and 'line' are unset for calls via call_user_func
402  // (T57634) This matches behaviour of
403  // Exception::getTraceAsString to instead display "[internal
404  // function]".
405  $text .= "{$pad}#{$level} [internal function]: ";
406  }
407 
408  if ( isset( $frame['class'] ) && isset( $frame['type'] ) && isset( $frame['function'] ) ) {
409  $text .= $frame['class'] . $frame['type'] . $frame['function'];
410  } elseif ( isset( $frame['function'] ) ) {
411  $text .= $frame['function'];
412  } else {
413  $text .= 'NO_FUNCTION_GIVEN';
414  }
415 
416  if ( isset( $frame['args'] ) ) {
417  $text .= '(' . implode( ', ', $frame['args'] ) . ")\n";
418  } else {
419  $text .= "()\n";
420  }
421  }
422 
423  $level = $level + 1;
424  $text .= "{$pad}#{$level} {main}";
425 
426  return $text;
427  }
428 
440  public static function getRedactedTrace( $e ) {
441  return static::redactTrace( $e->getTrace() );
442  }
443 
454  public static function redactTrace( array $trace ) {
455  return array_map( function ( $frame ) {
456  if ( isset( $frame['args'] ) ) {
457  $frame['args'] = array_map( function ( $arg ) {
458  return is_object( $arg ) ? get_class( $arg ) : gettype( $arg );
459  }, $frame['args'] );
460  }
461  return $frame;
462  }, $trace );
463  }
464 
476  public static function getLogId( $e ) {
477  wfDeprecated( __METHOD__, '1.27' );
478  return WebRequest::getRequestId();
479  }
480 
488  public static function getURL() {
489  global $wgRequest;
490  if ( !isset( $wgRequest ) || $wgRequest instanceof FauxRequest ) {
491  return false;
492  }
493  return $wgRequest->getRequestURL();
494  }
495 
503  public static function getLogMessage( $e ) {
504  $id = WebRequest::getRequestId();
505  $type = get_class( $e );
506  $file = $e->getFile();
507  $line = $e->getLine();
508  $message = $e->getMessage();
509  $url = self::getURL() ?: '[no req]';
510 
511  return "[$id] $url $type from line $line of $file: $message";
512  }
513 
523  public static function getLogNormalMessage( $e ) {
524  $type = get_class( $e );
525  $file = $e->getFile();
526  $line = $e->getLine();
527  $message = $e->getMessage();
528 
529  return "[{exception_id}] {exception_url} $type from line $line of $file: $message";
530  }
531 
536  public static function getPublicLogMessage( $e ) {
537  $reqId = WebRequest::getRequestId();
538  $type = get_class( $e );
539  return '[' . $reqId . '] '
540  . gmdate( 'Y-m-d H:i:s' ) . ': '
541  . 'Fatal exception of type "' . $type . '"';
542  }
543 
555  public static function getLogContext( $e, $catcher = self::CAUGHT_BY_OTHER ) {
556  return [
557  'exception' => $e,
558  'exception_id' => WebRequest::getRequestId(),
559  'exception_url' => self::getURL() ?: '[no req]',
560  'caught_by' => $catcher
561  ];
562  }
563 
576  public static function getStructuredExceptionData( $e, $catcher = self::CAUGHT_BY_OTHER ) {
578 
579  $data = [
580  'id' => WebRequest::getRequestId(),
581  'type' => get_class( $e ),
582  'file' => $e->getFile(),
583  'line' => $e->getLine(),
584  'message' => $e->getMessage(),
585  'code' => $e->getCode(),
586  'url' => self::getURL() ?: null,
587  'caught_by' => $catcher
588  ];
589 
590  if ( $e instanceof ErrorException &&
591  ( error_reporting() & $e->getSeverity() ) === 0
592  ) {
593  // Flag surpressed errors
594  $data['suppressed'] = true;
595  }
596 
597  if ( $wgLogExceptionBacktrace ) {
598  $data['backtrace'] = self::getRedactedTrace( $e );
599  }
600 
601  $previous = $e->getPrevious();
602  if ( $previous !== null ) {
603  $data['previous'] = self::getStructuredExceptionData( $previous, $catcher );
604  }
605 
606  return $data;
607  }
608 
663  public static function jsonSerializeException(
664  $e, $pretty = false, $escaping = 0, $catcher = self::CAUGHT_BY_OTHER
665  ) {
666  return FormatJson::encode(
667  self::getStructuredExceptionData( $e, $catcher ),
668  $pretty,
669  $escaping
670  );
671  }
672 
683  public static function logException( $e, $catcher = self::CAUGHT_BY_OTHER ) {
684  if ( !( $e instanceof MWException ) || $e->isLoggable() ) {
685  $logger = LoggerFactory::getInstance( 'exception' );
686  $logger->error(
687  self::getLogNormalMessage( $e ),
688  self::getLogContext( $e, $catcher )
689  );
690 
691  $json = self::jsonSerializeException( $e, false, FormatJson::ALL_OK, $catcher );
692  if ( $json !== false ) {
693  $logger = LoggerFactory::getInstance( 'exception-json' );
694  $logger->error( $json, [ 'private' => true ] );
695  }
696 
697  Hooks::run( 'LogException', [ $e, false ] );
698  }
699  }
700 
709  protected static function logError(
710  ErrorException $e, $channel, $level = LogLevel::ERROR
711  ) {
712  $catcher = self::CAUGHT_BY_HANDLER;
713  // The set_error_handler callback is independent from error_reporting.
714  // Filter out unwanted errors manually (e.g. when
715  // Wikimedia\suppressWarnings is active).
716  $suppressed = ( error_reporting() & $e->getSeverity() ) === 0;
717  if ( !$suppressed ) {
718  $logger = LoggerFactory::getInstance( $channel );
719  $logger->log(
720  $level,
721  self::getLogNormalMessage( $e ),
722  self::getLogContext( $e, $catcher )
723  );
724  }
725 
726  // Include all errors in the json log (surpressed errors will be flagged)
727  $json = self::jsonSerializeException( $e, false, FormatJson::ALL_OK, $catcher );
728  if ( $json !== false ) {
729  $logger = LoggerFactory::getInstance( "{$channel}-json" );
730  $logger->log( $level, $json, [ 'private' => true ] );
731  }
732 
733  Hooks::run( 'LogException', [ $e, $suppressed ] );
734  }
735 }
The wiki should then use memcached to cache various data To use multiple just add more items to the array To increase the weight of a make its entry a array("192.168.0.1:11211", 2))
$wgLogExceptionBacktrace
If true, send the exception backtrace to the error log.
static getLogMessage( $e)
Get a message formatting the exception message and its origin.
static jsonSerializeException( $e, $pretty=false, $escaping=0, $catcher=self::CAUGHT_BY_OTHER)
Serialize an Exception object to JSON.
static getRequestId()
Get the unique request ID.
Definition: WebRequest.php:275
static getLogId( $e)
Get the ID for this exception.
Apache License January AND DISTRIBUTION Definitions License shall mean the terms and conditions for use
static handleFatalError( $level=null, $message=null, $file=null, $line=null, $context=null, $trace=null)
Dual purpose callback used as both a set_error_handler() callback and a registered shutdown function...
static getRedactedTrace( $e)
Return a copy of an exception&#39;s backtrace as an array.
div flags Integer display flags(NO_ACTION_LINK, NO_EXTRA_USER_LINKS) 'LogException' returning false will NOT prevent logging $e
Definition: hooks.txt:2173
const ALL_OK
Skip escaping as many characters as reasonably possible.
Definition: FormatJson.php:55
injection txt This is an overview of how MediaWiki makes use of dependency injection The design described here grew from the discussion of RFC T384 The term dependency this means that anything an object needs to operate should be injected from the the object itself should only know narrow no concrete implementation of the logic it relies on The requirement to inject everything typically results in an architecture that based on two main types of and essentially stateless service objects that use other service objects to operate on the value objects As of the beginning MediaWiki is only starting to use the DI approach Much of the code still relies on global state or direct resulting in a highly cyclical dependency MediaWikiServices
Definition: injection.txt:23
static encode( $value, $pretty=false, $escaping=0)
Returns the JSON representation of a value.
Definition: FormatJson.php:115
static rollbackMasterChangesAndLog( $e)
Roll back any open database transactions and log the stack trace of the exception.
A helper class for throttling authentication attempts.
static getRedactedTraceAsString( $e)
Generate a string representation of an exception&#39;s stack trace.
static configuration should be added through ResourceLoaderGetConfigVars instead can be used to get the real title e g db for database replication lag or jobqueue for job queue size converted to pseudo seconds It is possible to add more fields and they will be returned to the user in the API response after the basic globals have been set but before ordinary actions take place or wrap services the preferred way to define a new service is the $wgServiceWiringFiles array $services
Definition: hooks.txt:2221
static handleError( $level, $message, $file=null, $line=null)
Handler for set_error_handler() callback notifications.
static logException( $e, $catcher=self::CAUGHT_BY_OTHER)
Log an exception to the exception log (if enabled).
static getURL()
If the exception occurred in the course of responding to a request, returns the requested URL...
wfIsCLI()
Check if we are running from the commandline.
static redactTrace(array $trace)
Redact a stacktrace generated by Exception::getTrace(), debug_backtrace() or similar means...
static logError(ErrorException $e, $channel, $level=LogLevel::ERROR)
Log an exception that wasn&#39;t thrown but made to wrap an error.
static handleException( $e)
Exception handler which simulates the appropriate catch() handling:
This document is intended to provide useful advice for parties seeking to redistribute MediaWiki to end users It s targeted particularly at maintainers for Linux since it s been observed that distribution packages of MediaWiki often break We ve consistently had to recommend that users seeking support use official tarballs instead of their distribution s and this often solves whatever problem the user is having It would be nice if this could such as
Definition: distributors.txt:9
static report( $e)
Report an exception to the user.
static output( $e, $mode, $eNew=null)
static getGlobalRequestURL()
Return the path and query string portion of the main request URI.
Definition: WebRequest.php:798
injection txt This is an overview of how MediaWiki makes use of dependency injection The design described here grew from the discussion of RFC T384 The term dependency this means that anything an object needs to operate should be injected from the the object itself should only know narrow no concrete implementation of the logic it relies on The requirement to inject everything typically results in an architecture that based on two main types of and essentially stateless service objects that use other service objects to operate on the value objects As of the beginning MediaWiki is only starting to use the DI approach Much of the code still relies on global state or direct resulting in a highly cyclical dependency which acts as the top level factory for services in MediaWiki which can be used to gain access to default instances of various services MediaWikiServices however also allows new services to be defined and default services to be redefined Services are defined or redefined by providing a callback the instantiator that will return a new instance of the service When it will create an instance of MediaWikiServices and populate it with the services defined in the files listed by thereby bootstrapping the DI framework Per $wgServiceWiringFiles lists includes ServiceWiring php
Definition: injection.txt:35
static installHandler()
Install handlers with PHP.
you have access to all of the normal MediaWiki so you can get a DB use the etc For full docs on the Maintenance class
Definition: maintenance.txt:52
wfDeprecated( $function, $version=false, $component=false, $callerOffset=2)
Throws a warning that $function is deprecated.
$line
Definition: cdb.php:59
do that in ParserLimitReportFormat instead use this to modify the parameters of the image all existing parser cache entries will be invalid To avoid you ll need to handle that somehow(e.g. with the RejectParserCacheValue hook) because MediaWiki won 't do it for you. & $defaults also a ContextSource after deleting those rows but within the same transaction you ll probably need to make sure the header is varied on and they can depend only on the ResourceLoaderContext $context
Definition: hooks.txt:2626
Using a hook running we can avoid having all this option specific stuff in our mainline code Using the function We ve cleaned up the code here by removing clumps of infrequently used code and moving them off somewhere else It s much easier for someone working with this code to see what s _really_ going on
Definition: hooks.txt:77
MediaWiki Logger LoggerFactory implements a PSR [0] compatible message logging system Named Psr Log LoggerInterface instances can be obtained from the MediaWiki Logger LoggerFactory::getInstance() static method. MediaWiki\Logger\LoggerFactory expects a class implementing the MediaWiki\Logger\Spi interface to act as a factory for new Psr\Log\LoggerInterface instances. The "Spi" in MediaWiki\Logger\Spi stands for "service provider interface". An SPI is an API intended to be implemented or extended by a third party. This software design pattern is intended to enable framework extension and replaceable components. It is specifically used in the MediaWiki\Logger\LoggerFactory service to allow alternate PSR-3 logging implementations to be easily integrated with MediaWiki. The service provider interface allows the backend logging library to be implemented in multiple ways. The $wgMWLoggerDefaultSpi global provides the classname of the default MediaWiki\Logger\Spi implementation to be loaded at runtime. This can either be the name of a class implementing the MediaWiki\Logger\Spi with a zero argument const ructor or a callable that will return an MediaWiki\Logger\Spi instance. Alternately the MediaWiki\Logger\LoggerFactory MediaWiki Logger LoggerFactory
Definition: logger.txt:5
static prettyPrintTrace(array $trace, $pad='')
Generate a string representation of a stacktrace.
static handleUncaughtException( $e)
Callback to use with PHP&#39;s set_exception_handler.
if(! $wgDBerrorLogTZ) $wgRequest
Definition: Setup.php:747
static getLogNormalMessage( $e)
Get a normalised message for formatting with PSR-3 log event context.
$wgPropagateErrors
If true, the MediaWiki error handler passes errors/warnings to the default error handler after loggin...
div flags Integer display flags(NO_ACTION_LINK, NO_EXTRA_USER_LINKS) 'LogException' returning false will NOT prevent logging a wrapping ErrorException $suppressed
Definition: hooks.txt:2173
static getStructuredExceptionData( $e, $catcher=self::CAUGHT_BY_OTHER)
Get a structured representation of an Exception.
static $fatalErrorTypes
Error types that, if unhandled, are fatal to the request.
static getPublicLogMessage( $e)
Database error base class.
Definition: DBError.php:30
static getLogContext( $e, $catcher=self::CAUGHT_BY_OTHER)
Get a PSR-3 log event context from an Exception.
static run( $event, array $args=[], $deprecatedVersion=null)
Call hook functions defined in Hooks::register and $wgHooks.
Definition: Hooks.php:200