3ae8eb2416
MWExceptionHandler::handleFatalError() is installed as a shutdown function to inspect `error_get_last()` output and log the error via MWExceptionHandler::logError(). The error is examined to determine if it is a missing class error so that a descriptive log message can be provided instructing the server administrator on 3rd party library installation methods. Bug: T74777 Change-Id: I04748626487022c51050ffa7846236947a082d68
497 lines
14 KiB
PHP
497 lines
14 KiB
PHP
<?php
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/**
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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*/
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/**
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* Handler class for MWExceptions
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* @ingroup Exception
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*/
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class MWExceptionHandler {
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protected static $reservedMemory;
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protected static $fatalErrorTypes = array(
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E_ERROR, E_PARSE, E_CORE_ERROR, E_COMPILE_ERROR, E_USER_ERROR,
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/* HHVM's FATAL_ERROR level */ 16777217,
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);
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/**
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* Install handlers with PHP.
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*/
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public static function installHandler() {
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set_exception_handler( array( 'MWExceptionHandler', 'handleException' ) );
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set_error_handler( array( 'MWExceptionHandler', 'handleError' ) );
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// Reserve 16k of memory so we can report OOM fatals
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self::$reservedMemory = str_repeat( ' ', 16384 );
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register_shutdown_function(
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array( 'MWExceptionHandler', 'handleFatalError' )
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);
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}
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/**
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* Report an exception to the user
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* @param Exception $e
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*/
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protected static function report( Exception $e ) {
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global $wgShowExceptionDetails;
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$cmdLine = MWException::isCommandLine();
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if ( $e instanceof MWException ) {
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try {
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// Try and show the exception prettily, with the normal skin infrastructure
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$e->report();
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} catch ( Exception $e2 ) {
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// Exception occurred from within exception handler
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// Show a simpler message for the original exception,
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// don't try to invoke report()
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$message = "MediaWiki internal error.\n\n";
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if ( $wgShowExceptionDetails ) {
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$message .= 'Original exception: ' . self::getLogMessage( $e ) .
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"\nBacktrace:\n" . self::getRedactedTraceAsString( $e ) .
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"\n\nException caught inside exception handler: " . self::getLogMessage( $e2 ) .
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"\nBacktrace:\n" . self::getRedactedTraceAsString( $e2 );
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} else {
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$message .= "Exception caught inside exception handler.\n\n" .
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"Set \$wgShowExceptionDetails = true; at the bottom of LocalSettings.php " .
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"to show detailed debugging information.";
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}
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$message .= "\n";
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if ( $cmdLine ) {
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self::printError( $message );
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} else {
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echo nl2br( htmlspecialchars( $message ) ) . "\n";
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}
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}
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} else {
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$message = "Unexpected non-MediaWiki exception encountered, of type \"" .
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get_class( $e ) . "\"";
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if ( $wgShowExceptionDetails ) {
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$message .= "\n" . MWExceptionHandler::getLogMessage( $e ) . "\nBacktrace:\n" .
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self::getRedactedTraceAsString( $e ) . "\n";
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}
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if ( $cmdLine ) {
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self::printError( $message );
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} else {
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echo nl2br( htmlspecialchars( $message ) ) . "\n";
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}
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}
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}
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/**
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* Print a message, if possible to STDERR.
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* Use this in command line mode only (see isCommandLine)
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*
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* @param string $message Failure text
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*/
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public static function printError( $message ) {
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# NOTE: STDERR may not be available, especially if php-cgi is used from the
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# command line (bug #15602). Try to produce meaningful output anyway. Using
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# echo may corrupt output to STDOUT though.
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if ( defined( 'STDERR' ) ) {
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fwrite( STDERR, $message );
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} else {
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echo $message;
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}
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}
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/**
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* If there are any open database transactions, roll them back and log
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* the stack trace of the exception that should have been caught so the
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* transaction could be aborted properly.
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*
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* @since 1.23
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* @param Exception $e
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*/
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public static function rollbackMasterChangesAndLog( Exception $e ) {
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$factory = wfGetLBFactory();
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if ( $factory->hasMasterChanges() ) {
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wfDebugLog( 'Bug56269',
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'Exception thrown with an uncommited database transaction: ' .
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MWExceptionHandler::getLogMessage( $e ) . "\n" .
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$e->getTraceAsString()
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);
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$factory->rollbackMasterChanges();
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}
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}
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/**
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* Exception handler which simulates the appropriate catch() handling:
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*
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* try {
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* ...
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* } catch ( MWException $e ) {
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* $e->report();
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* } catch ( Exception $e ) {
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* echo $e->__toString();
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* }
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*
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* @since 1.25
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* @param Exception $e
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*/
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public static function handleException( $e ) {
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global $wgFullyInitialised;
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self::rollbackMasterChangesAndLog( $e );
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self::logException( $e );
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self::report( $e );
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// Final cleanup
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if ( $wgFullyInitialised ) {
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try {
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// uses $wgRequest, hence the $wgFullyInitialised condition
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wfLogProfilingData();
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} catch ( Exception $e ) {
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}
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}
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// Exit value should be nonzero for the benefit of shell jobs
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exit( 1 );
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}
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/**
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* @since 1.25
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* @param int $level Error level raised
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* @param string $message
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* @param string $file
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* @param int $line
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*/
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public static function handleError( $level, $message, $file = null, $line = null ) {
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// Map error constant to error name (reverse-engineer PHP error reporting)
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switch ( $level ) {
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case E_ERROR:
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case E_CORE_ERROR:
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case E_COMPILE_ERROR:
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case E_USER_ERROR:
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case E_RECOVERABLE_ERROR:
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case E_PARSE:
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$levelName = 'Error';
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break;
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case E_WARNING:
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case E_CORE_WARNING:
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case E_COMPILE_WARNING:
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case E_USER_WARNING:
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$levelName = 'Warning';
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break;
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case E_NOTICE:
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case E_USER_NOTICE:
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$levelName = 'Notice';
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break;
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case E_STRICT:
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$levelName = 'Strict Standards';
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break;
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case E_DEPRECATED:
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case E_USER_DEPRECATED:
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$levelName = 'Deprecated';
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break;
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case /* HHVM's FATAL_ERROR */ 16777217:
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$levelName = 'Fatal';
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break;
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default:
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$levelName = 'Unknown error';
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break;
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}
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$e = new ErrorException( "PHP $levelName: $message", 0, $level, $file, $line );
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self::logError( $e );
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// This handler is for logging only. Return false will instruct PHP
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// to continue regular handling.
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return false;
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}
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/**
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* Look for a fatal error as the cause of the request termination and log
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* as an exception.
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*
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* Special handling is included for missing class errors as they may
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* indicate that the user needs to install 3rd-party libraries via
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* Composer or other means.
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*
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* @since 1.25
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*/
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public static function handleFatalError() {
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self::$reservedMemory = null;
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$lastError = error_get_last();
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if ( $lastError &&
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isset( $lastError['type'] ) &&
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in_array( $lastError['type'], self::$fatalErrorTypes )
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) {
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$msg = "Fatal Error: {$lastError['message']}";
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// HHVM: Class undefined: foo
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// PHP5: Class 'foo' not found
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if ( preg_match( "/Class (undefined: \w+|'\w+' not found)/",
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$lastError['message']
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) ) {
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$msg = <<<TXT
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{$msg}
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MediaWiki or an installed extension requires this class but it is not embedded directly in MediaWiki's git repository and must be installed separately by the end user.
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Please see <a href="https://www.mediawiki.org/wiki/Download_from_Git#Fetch_external_libraries">mediawiki.org</a> for help on installing the required components.
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TXT;
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}
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$e = new ErrorException( $msg, 0, $lastError['type'] );
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self::logError( $e );
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}
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}
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/**
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* Generate a string representation of an exception's stack trace
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*
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* Like Exception::getTraceAsString, but replaces argument values with
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* argument type or class name.
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*
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* @param Exception $e
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* @return string
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*/
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public static function getRedactedTraceAsString( Exception $e ) {
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$text = '';
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foreach ( self::getRedactedTrace( $e ) as $level => $frame ) {
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if ( isset( $frame['file'] ) && isset( $frame['line'] ) ) {
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$text .= "#{$level} {$frame['file']}({$frame['line']}): ";
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} else {
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// 'file' and 'line' are unset for calls via call_user_func (bug 55634)
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// This matches behaviour of Exception::getTraceAsString to instead
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// display "[internal function]".
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$text .= "#{$level} [internal function]: ";
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}
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if ( isset( $frame['class'] ) ) {
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$text .= $frame['class'] . $frame['type'] . $frame['function'];
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} else {
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$text .= $frame['function'];
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}
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if ( isset( $frame['args'] ) ) {
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$text .= '(' . implode( ', ', $frame['args'] ) . ")\n";
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} else {
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$text .= "()\n";
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}
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}
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$level = $level + 1;
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$text .= "#{$level} {main}";
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return $text;
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}
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/**
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* Return a copy of an exception's backtrace as an array.
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*
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* Like Exception::getTrace, but replaces each element in each frame's
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* argument array with the name of its class (if the element is an object)
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* or its type (if the element is a PHP primitive).
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*
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* @since 1.22
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* @param Exception $e
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* @return array
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*/
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public static function getRedactedTrace( Exception $e ) {
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return array_map( function ( $frame ) {
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if ( isset( $frame['args'] ) ) {
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$frame['args'] = array_map( function ( $arg ) {
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return is_object( $arg ) ? get_class( $arg ) : gettype( $arg );
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}, $frame['args'] );
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}
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return $frame;
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}, $e->getTrace() );
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}
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/**
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* Get the ID for this exception.
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*
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* The ID is saved so that one can match the one output to the user (when
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* $wgShowExceptionDetails is set to false), to the entry in the debug log.
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*
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* @since 1.22
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* @param Exception $e
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* @return string
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*/
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public static function getLogId( Exception $e ) {
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if ( !isset( $e->_mwLogId ) ) {
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$e->_mwLogId = wfRandomString( 8 );
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}
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return $e->_mwLogId;
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}
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/**
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* If the exception occurred in the course of responding to a request,
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* returns the requested URL. Otherwise, returns false.
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*
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* @since 1.23
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* @return string|bool
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*/
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public static function getURL() {
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global $wgRequest;
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if ( !isset( $wgRequest ) || $wgRequest instanceof FauxRequest ) {
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return false;
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}
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return $wgRequest->getRequestURL();
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}
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/**
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* Get a message formatting the exception message and its origin.
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*
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* @since 1.22
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* @param Exception $e
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* @return string
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*/
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public static function getLogMessage( Exception $e ) {
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$id = self::getLogId( $e );
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$type = get_class( $e );
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$file = $e->getFile();
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$line = $e->getLine();
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$message = $e->getMessage();
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$url = self::getURL() ?: '[no req]';
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return "[$id] $url $type from line $line of $file: $message";
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}
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/**
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* Serialize an Exception object to JSON.
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*
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* The JSON object will have keys 'id', 'file', 'line', 'message', and
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* 'url'. These keys map to string values, with the exception of 'line',
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* which is a number, and 'url', which may be either a string URL or or
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* null if the exception did not occur in the context of serving a web
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* request.
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*
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* If $wgLogExceptionBacktrace is true, it will also have a 'backtrace'
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* key, mapped to the array return value of Exception::getTrace, but with
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* each element in each frame's "args" array (if set) replaced with the
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* argument's class name (if the argument is an object) or type name (if
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* the argument is a PHP primitive).
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*
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* @par Sample JSON record ($wgLogExceptionBacktrace = false):
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* @code
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* {
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* "id": "c41fb419",
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* "type": "MWException",
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* "file": "/var/www/mediawiki/includes/cache/MessageCache.php",
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* "line": 704,
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* "message": "Non-string key given",
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* "url": "/wiki/Main_Page"
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* }
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* @endcode
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*
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* @par Sample JSON record ($wgLogExceptionBacktrace = true):
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* @code
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* {
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* "id": "dc457938",
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* "type": "MWException",
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* "file": "/vagrant/mediawiki/includes/cache/MessageCache.php",
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* "line": 704,
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* "message": "Non-string key given",
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* "url": "/wiki/Main_Page",
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* "backtrace": [{
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* "file": "/vagrant/mediawiki/extensions/VisualEditor/VisualEditor.hooks.php",
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* "line": 80,
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* "function": "get",
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* "class": "MessageCache",
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* "type": "->",
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* "args": ["array"]
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* }]
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* }
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* @endcode
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*
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* @since 1.23
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* @param Exception $e
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* @param bool $pretty Add non-significant whitespace to improve readability (default: false).
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* @param int $escaping Bitfield consisting of FormatJson::.*_OK class constants.
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* @return string|bool JSON string if successful; false upon failure
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*/
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public static function jsonSerializeException( Exception $e, $pretty = false, $escaping = 0 ) {
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global $wgLogExceptionBacktrace;
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$exceptionData = array(
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'id' => self::getLogId( $e ),
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'type' => get_class( $e ),
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'file' => $e->getFile(),
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'line' => $e->getLine(),
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'message' => $e->getMessage(),
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);
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// Because MediaWiki is first and foremost a web application, we set a
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// 'url' key unconditionally, but set it to null if the exception does
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// not occur in the context of a web request, as a way of making that
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// fact visible and explicit.
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$exceptionData['url'] = self::getURL() ?: null;
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if ( $wgLogExceptionBacktrace ) {
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// Argument values may not be serializable, so redact them.
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$exceptionData['backtrace'] = self::getRedactedTrace( $e );
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}
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return FormatJson::encode( $exceptionData, $pretty, $escaping );
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}
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/**
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* Log an exception to the exception log (if enabled).
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*
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* This method must not assume the exception is an MWException,
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* it is also used to handle PHP exceptions or exceptions from other libraries.
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*
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* @since 1.22
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* @param Exception $e
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*/
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public static function logException( Exception $e ) {
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global $wgLogExceptionBacktrace;
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if ( !( $e instanceof MWException ) || $e->isLoggable() ) {
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$log = self::getLogMessage( $e );
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if ( $wgLogExceptionBacktrace ) {
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wfDebugLog( 'exception', $log . "\n" . $e->getTraceAsString() );
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} else {
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wfDebugLog( 'exception', $log );
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}
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$json = self::jsonSerializeException( $e, false, FormatJson::ALL_OK );
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if ( $json !== false ) {
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wfDebugLog( 'exception-json', $json, 'private' );
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}
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}
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}
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/**
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* Log an exception that wasn't thrown but made to wrap an error.
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*
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* @since 1.25
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* @param Exception $e
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*/
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protected static function logError( Exception $e ) {
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global $wgLogExceptionBacktrace;
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$log = self::getLogMessage( $e );
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if ( $wgLogExceptionBacktrace ) {
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wfDebugLog( 'error', $log . "\n" . $e->getTraceAsString() );
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} else {
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wfDebugLog( 'error', $log );
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}
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}
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}
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