first commit

19 files changed, 2066 insertions, 0 deletions

diff --git a/www/wiki/includes/exception/BadRequestError.php b/www/wiki/includes/exception/BadRequestError.php
new file mode 100644
index 00000000..5fcf0e62
--- /dev/null
+++ b/www/wiki/includes/exception/BadRequestError.php
@@ -0,0 +1,34 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * An error page that emits an HTTP 400 Bad Request status code.
+ *
+ * @since 1.28
+ * @ingroup Exception
+ */
+class BadRequestError extends ErrorPageError {
+
+	public function report() {
+		global $wgOut;
+		$wgOut->setStatusCode( 400 );
+		parent::report();
+	}
+}
diff --git a/www/wiki/includes/exception/BadTitleError.php b/www/wiki/includes/exception/BadTitleError.php
new file mode 100644
index 00000000..40c18a42
--- /dev/null
+++ b/www/wiki/includes/exception/BadTitleError.php
@@ -0,0 +1,49 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Show an error page on a badtitle.
+ *
+ * Uses BadRequestError to emit a 400 HTTP error code to ensure caching proxies and
+ * mobile browsers know not to cache it as valid content. (T35646)
+ *
+ * @since 1.19
+ * @ingroup Exception
+ */
+class BadTitleError extends BadRequestError {
+	/**
+	 * @param string|Message|MalformedTitleException $msg A message key (default: 'badtitletext'), or
+	 *     a MalformedTitleException to figure out things from
+	 * @param array $params Parameter to wfMessage()
+	 */
+	public function __construct( $msg = 'badtitletext', $params = [] ) {
+		if ( $msg instanceof MalformedTitleException ) {
+			$errorMessage = $msg->getErrorMessage();
+			if ( !$errorMessage ) {
+				parent::__construct( 'badtitle', 'badtitletext', [] );
+			} else {
+				$errorMessageParams = $msg->getErrorMessageParameters();
+				parent::__construct( 'badtitle', $errorMessage, $errorMessageParams );
+			}
+		} else {
+			parent::__construct( 'badtitle', $msg, $params );
+		}
+	}
+}
diff --git a/www/wiki/includes/exception/CannotCreateActorException.php b/www/wiki/includes/exception/CannotCreateActorException.php
new file mode 100644
index 00000000..7c7ccfc4
--- /dev/null
+++ b/www/wiki/includes/exception/CannotCreateActorException.php
@@ -0,0 +1,29 @@
+<?php
+/**
+ * Exception thrown when some operation failed
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ *
+ * @since 1.31
+ */
+
+/**
+ * Exception thrown when an actor can't be created.
+ */
+class CannotCreateActorException extends RuntimeException {
+}
diff --git a/www/wiki/includes/exception/ErrorPageError.php b/www/wiki/includes/exception/ErrorPageError.php
new file mode 100644
index 00000000..4b181267
--- /dev/null
+++ b/www/wiki/includes/exception/ErrorPageError.php
@@ -0,0 +1,72 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * An error page which can definitely be safely rendered using the OutputPage.
+ *
+ * @since 1.7
+ * @ingroup Exception
+ */
+class ErrorPageError extends MWException implements ILocalizedException {
+	public $title, $msg, $params;
+
+	/**
+	 * Note: these arguments are keys into wfMessage(), not text!
+	 *
+	 * @param string|Message $title Message key (string) for page title, or a Message object
+	 * @param string|Message $msg Message key (string) for error text, or a Message object
+	 * @param array $params Array with parameters to wfMessage()
+	 */
+	public function __construct( $title, $msg, $params = [] ) {
+		$this->title = $title;
+		$this->msg = $msg;
+		$this->params = $params;
+
+		// T46111: Messages in the log files should be in English and not
+		// customized by the local wiki. So get the default English version for
+		// passing to the parent constructor. Our overridden report() below
+		// makes sure that the page shown to the user is not forced to English.
+		$enMsg = $this->getMessageObject();
+		$enMsg->inLanguage( 'en' )->useDatabase( false );
+		parent::__construct( $enMsg->text() );
+	}
+
+	/**
+	 * Return a Message object for this exception
+	 * @since 1.29
+	 * @return Message
+	 */
+	public function getMessageObject() {
+		if ( $this->msg instanceof Message ) {
+			return clone $this->msg;
+		}
+		return wfMessage( $this->msg, $this->params );
+	}
+
+	public function report() {
+		if ( self::isCommandLine() || defined( 'MW_API' ) ) {
+			parent::report();
+		} else {
+			global $wgOut;
+			$wgOut->showErrorPage( $this->title, $this->msg, $this->params );
+			$wgOut->output();
+		}
+	}
+}
diff --git a/www/wiki/includes/exception/FatalError.php b/www/wiki/includes/exception/FatalError.php
new file mode 100644
index 00000000..a7d672fa
--- /dev/null
+++ b/www/wiki/includes/exception/FatalError.php
@@ -0,0 +1,43 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Exception class which takes an HTML error message, and does not
+ * produce a backtrace. Replacement for OutputPage::fatalError().
+ *
+ * @since 1.7
+ * @ingroup Exception
+ */
+class FatalError extends MWException {
+
+	/**
+	 * @return string
+	 */
+	public function getHTML() {
+		return $this->getMessage();
+	}
+
+	/**
+	 * @return string
+	 */
+	public function getText() {
+		return $this->getMessage();
+	}
+}
diff --git a/www/wiki/includes/exception/HttpError.php b/www/wiki/includes/exception/HttpError.php
new file mode 100644
index 00000000..f464d8af
--- /dev/null
+++ b/www/wiki/includes/exception/HttpError.php
@@ -0,0 +1,129 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+use MediaWiki\Logger\LoggerFactory;
+
+/**
+ * Show an error that looks like an HTTP server error.
+ * Replacement for wfHttpError().
+ *
+ * @since 1.19
+ * @ingroup Exception
+ */
+class HttpError extends MWException {
+	private $httpCode, $header, $content;
+
+	/**
+	 * @param int $httpCode HTTP status code to send to the client
+	 * @param string|Message $content Content of the message
+	 * @param string|Message|null $header Content of the header (\<title\> and \<h1\>)
+	 */
+	public function __construct( $httpCode, $content, $header = null ) {
+		parent::__construct( $content );
+		$this->httpCode = (int)$httpCode;
+		$this->header = $header;
+		$this->content = $content;
+	}
+
+	/**
+	 * We don't want the default exception logging as we got our own logging set
+	 * up in self::report.
+	 *
+	 * @see MWException::isLoggable
+	 *
+	 * @since 1.24
+	 * @return bool
+	 */
+	public function isLoggable() {
+		return false;
+	}
+
+	/**
+	 * Returns the HTTP status code supplied to the constructor.
+	 *
+	 * @return int
+	 */
+	public function getStatusCode() {
+		return $this->httpCode;
+	}
+
+	/**
+	 * Report and log the HTTP error.
+	 * Sends the appropriate HTTP status code and outputs an
+	 * HTML page with an error message.
+	 */
+	public function report() {
+		$this->doLog();
+
+		HttpStatus::header( $this->httpCode );
+		header( 'Content-type: text/html; charset=utf-8' );
+
+		print $this->getHTML();
+	}
+
+	private function doLog() {
+		$logger = LoggerFactory::getInstance( 'HttpError' );
+		$content = $this->content;
+
+		if ( $content instanceof Message ) {
+			$content = $content->text();
+		}
+
+		$context = [
+			'file' => $this->getFile(),
+			'line' => $this->getLine(),
+			'http_code' => $this->httpCode,
+		];
+
+		$logMsg = "$content ({http_code}) from {file}:{line}";
+
+		if ( $this->getStatusCode() < 500 ) {
+			$logger->info( $logMsg, $context );
+		} else {
+			$logger->error( $logMsg, $context );
+		}
+	}
+
+	/**
+	 * Returns HTML for reporting the HTTP error.
+	 * This will be a minimal but complete HTML document.
+	 *
+	 * @return string HTML
+	 */
+	public function getHTML() {
+		if ( $this->header === null ) {
+			$titleHtml = htmlspecialchars( HttpStatus::getMessage( $this->httpCode ) );
+		} elseif ( $this->header instanceof Message ) {
+			$titleHtml = $this->header->escaped();
+		} else {
+			$titleHtml = htmlspecialchars( $this->header );
+		}
+
+		if ( $this->content instanceof Message ) {
+			$contentHtml = $this->content->escaped();
+		} else {
+			$contentHtml = nl2br( htmlspecialchars( $this->content ) );
+		}
+
+		return "<!DOCTYPE html>\n" .
+		"<html><head><title>$titleHtml</title></head>\n" .
+		"<body><h1>$titleHtml</h1><p>$contentHtml</p></body></html>\n";
+	}
+}
diff --git a/www/wiki/includes/exception/LocalizedException.php b/www/wiki/includes/exception/LocalizedException.php
new file mode 100644
index 00000000..f5f8c84e
--- /dev/null
+++ b/www/wiki/includes/exception/LocalizedException.php
@@ -0,0 +1,66 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Interface for MediaWiki-localized exceptions
+ *
+ * @since 1.29
+ * @ingroup Exception
+ */
+interface ILocalizedException {
+	/**
+	 * Return a Message object for this exception
+	 * @return Message
+	 */
+	public function getMessageObject();
+}
+
+/**
+ * Basic localized exception.
+ *
+ * @since 1.29
+ * @ingroup Exception
+ * @note Don't use this in a situation where MessageCache is not functional.
+ */
+class LocalizedException extends Exception implements ILocalizedException {
+	/** @var string|array|MessageSpecifier */
+	protected $messageSpec;
+
+	/**
+	 * @param string|array|MessageSpecifier $messageSpec See Message::newFromSpecifier
+	 * @param int $code
+	 * @param Exception|Throwable $previous The previous exception used for the exception chaining.
+	 */
+	public function __construct( $messageSpec, $code = 0, $previous = null ) {
+		$this->messageSpec = $messageSpec;
+
+		// Exception->getMessage() should be in plain English, not localized.
+		// So fetch the English version of the message, without local
+		// customizations, and make a basic attempt to turn markup into text.
+		$msg = $this->getMessageObject()->inLanguage( 'en' )->useDatabase( false )->text();
+		$msg = preg_replace( '!</?(var|kbd|samp|code)>!', '"', $msg );
+		$msg = Sanitizer::stripAllTags( $msg );
+		parent::__construct( $msg, $code, $previous );
+	}
+
+	public function getMessageObject() {
+		return Message::newFromSpecifier( $this->messageSpec );
+	}
+}
diff --git a/www/wiki/includes/exception/MWContentSerializationException.php b/www/wiki/includes/exception/MWContentSerializationException.php
new file mode 100644
index 00000000..500cf7ce
--- /dev/null
+++ b/www/wiki/includes/exception/MWContentSerializationException.php
@@ -0,0 +1,8 @@
+<?php
+/**
+ * Exception representing a failure to serialize or unserialize a content object.
+ *
+ * @ingroup Content
+ */
+class MWContentSerializationException extends MWException {
+}
diff --git a/www/wiki/includes/exception/MWException.php b/www/wiki/includes/exception/MWException.php
new file mode 100644
index 00000000..b3e9422b
--- /dev/null
+++ b/www/wiki/includes/exception/MWException.php
@@ -0,0 +1,230 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * MediaWiki exception
+ *
+ * @ingroup Exception
+ */
+class MWException extends Exception {
+	/**
+	 * Should the exception use $wgOut to output the error?
+	 *
+	 * @return bool
+	 */
+	public function useOutputPage() {
+		return $this->useMessageCache() &&
+		!empty( $GLOBALS['wgFullyInitialised'] ) &&
+		!empty( $GLOBALS['wgOut'] ) &&
+		!defined( 'MEDIAWIKI_INSTALL' );
+	}
+
+	/**
+	 * Whether to log this exception in the exception debug log.
+	 *
+	 * @since 1.23
+	 * @return bool
+	 */
+	public function isLoggable() {
+		return true;
+	}
+
+	/**
+	 * Can the extension use the Message class/wfMessage to get i18n-ed messages?
+	 *
+	 * @return bool
+	 */
+	public function useMessageCache() {
+		global $wgLang;
+
+		foreach ( $this->getTrace() as $frame ) {
+			if ( isset( $frame['class'] ) && $frame['class'] === LocalisationCache::class ) {
+				return false;
+			}
+		}
+
+		return $wgLang instanceof Language;
+	}
+
+	/**
+	 * Get a message from i18n
+	 *
+	 * @param string $key Message name
+	 * @param string $fallback Default message if the message cache can't be
+	 *                  called by the exception
+	 * The function also has other parameters that are arguments for the message
+	 * @return string Message with arguments replaced
+	 */
+	public function msg( $key, $fallback /*[, params...] */ ) {
+		$args = array_slice( func_get_args(), 2 );
+
+		if ( $this->useMessageCache() ) {
+			try {
+				return wfMessage( $key, $args )->text();
+			} catch ( Exception $e ) {
+			}
+		}
+		return wfMsgReplaceArgs( $fallback, $args );
+	}
+
+	/**
+	 * If $wgShowExceptionDetails is true, return a HTML message with a
+	 * backtrace to the error, otherwise show a message to ask to set it to true
+	 * to show that information.
+	 *
+	 * @return string Html to output
+	 */
+	public function getHTML() {
+		global $wgShowExceptionDetails;
+
+		if ( $wgShowExceptionDetails ) {
+			return '<p>' . nl2br( htmlspecialchars( MWExceptionHandler::getLogMessage( $this ) ) ) .
+			'</p><p>Backtrace:</p><p>' .
+			nl2br( htmlspecialchars( MWExceptionHandler::getRedactedTraceAsString( $this ) ) ) .
+			"</p>\n";
+		} else {
+			$logId = WebRequest::getRequestId();
+			$type = static::class;
+			return Html::errorBox(
+			htmlspecialchars(
+				'[' . $logId . '] ' .
+				gmdate( 'Y-m-d H:i:s' ) . ": " .
+				$this->msg( "internalerror-fatal-exception",
+					"Fatal exception of type $1",
+					$type,
+					$logId,
+					MWExceptionHandler::getURL( $this )
+				)
+			) ) .
+			"<!-- Set \$wgShowExceptionDetails = true; " .
+			"at the bottom of LocalSettings.php to show detailed " .
+			"debugging information. -->";
+		}
+	}
+
+	/**
+	 * Get the text to display when reporting the error on the command line.
+	 * If $wgShowExceptionDetails is true, return a text message with a
+	 * backtrace to the error.
+	 *
+	 * @return string
+	 */
+	public function getText() {
+		global $wgShowExceptionDetails;
+
+		if ( $wgShowExceptionDetails ) {
+			return MWExceptionHandler::getLogMessage( $this ) .
+			"\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $this ) . "\n";
+		} else {
+			return "Set \$wgShowExceptionDetails = true; " .
+			"in LocalSettings.php to show detailed debugging information.\n";
+		}
+	}
+
+	/**
+	 * Return the title of the page when reporting this error in a HTTP response.
+	 *
+	 * @return string
+	 */
+	public function getPageTitle() {
+		return $this->msg( 'internalerror', 'Internal error' );
+	}
+
+	/**
+	 * Output the exception report using HTML.
+	 */
+	public function reportHTML() {
+		global $wgOut, $wgSitename;
+		if ( $this->useOutputPage() ) {
+			$wgOut->prepareErrorPage( $this->getPageTitle() );
+
+			$wgOut->addHTML( $this->getHTML() );
+
+			$wgOut->output();
+		} else {
+			self::header( 'Content-Type: text/html; charset=utf-8' );
+			echo "<!DOCTYPE html>\n" .
+				'<html><head>' .
+				// Mimick OutputPage::setPageTitle behaviour
+				'<title>' .
+				htmlspecialchars( $this->msg( 'pagetitle', "$1 - $wgSitename", $this->getPageTitle() ) ) .
+				'</title>' .
+				'<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
+				"</head><body>\n";
+
+			echo $this->getHTML();
+
+			echo "</body></html>\n";
+		}
+	}
+
+	/**
+	 * Output a report about the exception and takes care of formatting.
+	 * It will be either HTML or plain text based on isCommandLine().
+	 */
+	public function report() {
+		global $wgMimeType;
+
+		if ( defined( 'MW_API' ) ) {
+			// Unhandled API exception, we can't be sure that format printer is alive
+			self::header( 'MediaWiki-API-Error: internal_api_error_' . static::class );
+			wfHttpError( 500, 'Internal Server Error', $this->getText() );
+		} elseif ( self::isCommandLine() ) {
+			$message = $this->getText();
+			// T17602: STDERR may not be available
+			if ( !defined( 'MW_PHPUNIT_TEST' ) && defined( 'STDERR' ) ) {
+				fwrite( STDERR, $message );
+			} else {
+				echo $message;
+			}
+		} else {
+			self::statusHeader( 500 );
+			self::header( "Content-Type: $wgMimeType; charset=utf-8" );
+
+			$this->reportHTML();
+		}
+	}
+
+	/**
+	 * Check whether we are in command line mode or not to report the exception
+	 * in the correct format.
+	 *
+	 * @return bool
+	 */
+	public static function isCommandLine() {
+		return !empty( $GLOBALS['wgCommandLineMode'] );
+	}
+
+	/**
+	 * Send a header, if we haven't already sent them. We shouldn't,
+	 * but sometimes we might in a weird case like Export
+	 * @param string $header
+	 */
+	private static function header( $header ) {
+		if ( !headers_sent() ) {
+			header( $header );
+		}
+	}
+	private static function statusHeader( $code ) {
+		if ( !headers_sent() ) {
+			HttpStatus::header( $code );
+		}
+	}
+}
diff --git a/www/wiki/includes/exception/MWExceptionHandler.php b/www/wiki/includes/exception/MWExceptionHandler.php
new file mode 100644
index 00000000..79f0a233
--- /dev/null
+++ b/www/wiki/includes/exception/MWExceptionHandler.php
@@ -0,0 +1,697 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+use MediaWiki\Logger\LoggerFactory;
+use MediaWiki\MediaWikiServices;
+use Psr\Log\LogLevel;
+use Wikimedia\Rdbms\DBError;
+
+/**
+ * Handler class for MWExceptions
+ * @ingroup Exception
+ */
+class MWExceptionHandler {
+	const CAUGHT_BY_HANDLER = 'mwe_handler'; // error reported by this exception handler
+	const CAUGHT_BY_OTHER = 'other'; // error reported by direct logException() call
+
+	/**
+	 * @var string $reservedMemory
+	 */
+	protected static $reservedMemory;
+	/**
+	 * @var array $fatalErrorTypes
+	 */
+	protected static $fatalErrorTypes = [
+		E_ERROR, E_PARSE, E_CORE_ERROR, E_COMPILE_ERROR, E_USER_ERROR,
+		/* HHVM's FATAL_ERROR level */ 16777217,
+	];
+	/**
+	 * @var bool $handledFatalCallback
+	 */
+	protected static $handledFatalCallback = false;
+
+	/**
+	 * Install handlers with PHP.
+	 */
+	public static function installHandler() {
+		set_exception_handler( 'MWExceptionHandler::handleUncaughtException' );
+		set_error_handler( 'MWExceptionHandler::handleError' );
+
+		// Reserve 16k of memory so we can report OOM fatals
+		self::$reservedMemory = str_repeat( ' ', 16384 );
+		register_shutdown_function( 'MWExceptionHandler::handleFatalError' );
+	}
+
+	/**
+	 * Report an exception to the user
+	 * @param Exception|Throwable $e
+	 */
+	protected static function report( $e ) {
+		try {
+			// Try and show the exception prettily, with the normal skin infrastructure
+			if ( $e instanceof MWException ) {
+				// Delegate to MWException until all subclasses are handled by
+				// MWExceptionRenderer and MWException::report() has been
+				// removed.
+				$e->report();
+			} else {
+				MWExceptionRenderer::output( $e, MWExceptionRenderer::AS_PRETTY );
+			}
+		} catch ( Exception $e2 ) {
+			// Exception occurred from within exception handler
+			// Show a simpler message for the original exception,
+			// don't try to invoke report()
+			MWExceptionRenderer::output( $e, MWExceptionRenderer::AS_RAW, $e2 );
+		}
+	}
+
+	/**
+	 * Roll back any open database transactions and log the stack trace of the exception
+	 *
+	 * This method is used to attempt to recover from exceptions
+	 *
+	 * @since 1.23
+	 * @param Exception|Throwable $e
+	 */
+	public static function rollbackMasterChangesAndLog( $e ) {
+		$services = MediaWikiServices::getInstance();
+		if ( !$services->isServiceDisabled( 'DBLoadBalancerFactory' ) ) {
+			// Rollback DBs to avoid transaction notices. This might fail
+			// to rollback some databases due to connection issues or exceptions.
+			// However, any sane DB driver will rollback implicitly anyway.
+			try {
+				$services->getDBLoadBalancerFactory()->rollbackMasterChanges( __METHOD__ );
+			} catch ( DBError $e2 ) {
+				// If the DB is unreacheable, rollback() will throw an error
+				// and the error report() method might need messages from the DB,
+				// which would result in an exception loop. PHP may escalate such
+				// errors to "Exception thrown without a stack frame" fatals, but
+				// it's better to be explicit here.
+				self::logException( $e2, self::CAUGHT_BY_HANDLER );
+			}
+		}
+
+		self::logException( $e, self::CAUGHT_BY_HANDLER );
+	}
+
+	/**
+	 * Callback to use with PHP's set_exception_handler.
+	 *
+	 * @since 1.31
+	 * @param Exception|Throwable $e
+	 */
+	public static function handleUncaughtException( $e ) {
+		self::handleException( $e );
+
+		// Make sure we don't claim success on exit for CLI scripts (T177414)
+		if ( wfIsCLI() ) {
+			register_shutdown_function(
+				function () {
+					exit( 255 );
+				}
+			);
+		}
+	}
+
+	/**
+	 * Exception handler which simulates the appropriate catch() handling:
+	 *
+	 *   try {
+	 *       ...
+	 *   } catch ( Exception $e ) {
+	 *       $e->report();
+	 *   } catch ( Exception $e ) {
+	 *       echo $e->__toString();
+	 *   }
+	 *
+	 * @since 1.25
+	 * @param Exception|Throwable $e
+	 */
+	public static function handleException( $e ) {
+		self::rollbackMasterChangesAndLog( $e );
+		self::report( $e );
+	}
+
+	/**
+	 * Handler for set_error_handler() callback notifications.
+	 *
+	 * Receive a callback from the interpreter for a raised error, create an
+	 * ErrorException, and log the exception to the 'error' logging
+	 * channel(s). If the raised error is a fatal error type (only under HHVM)
+	 * delegate to handleFatalError() instead.
+	 *
+	 * @since 1.25
+	 *
+	 * @param int $level Error level raised
+	 * @param string $message
+	 * @param string $file
+	 * @param int $line
+	 * @return bool
+	 *
+	 * @see logError()
+	 */
+	public static function handleError(
+		$level, $message, $file = null, $line = null
+	) {
+		global $wgPropagateErrors;
+
+		if ( in_array( $level, self::$fatalErrorTypes ) ) {
+			return call_user_func_array(
+				'MWExceptionHandler::handleFatalError', func_get_args()
+			);
+		}
+
+		// Map error constant to error name (reverse-engineer PHP error
+		// reporting)
+		switch ( $level ) {
+			case E_RECOVERABLE_ERROR:
+				$levelName = 'Error';
+				$severity = LogLevel::ERROR;
+				break;
+			case E_WARNING:
+			case E_CORE_WARNING:
+			case E_COMPILE_WARNING:
+			case E_USER_WARNING:
+				$levelName = 'Warning';
+				$severity = LogLevel::WARNING;
+				break;
+			case E_NOTICE:
+			case E_USER_NOTICE:
+				$levelName = 'Notice';
+				$severity = LogLevel::INFO;
+				break;
+			case E_STRICT:
+				$levelName = 'Strict Standards';
+				$severity = LogLevel::DEBUG;
+				break;
+			case E_DEPRECATED:
+			case E_USER_DEPRECATED:
+				$levelName = 'Deprecated';
+				$severity = LogLevel::INFO;
+				break;
+			default:
+				$levelName = 'Unknown error';
+				$severity = LogLevel::ERROR;
+				break;
+		}
+
+		$e = new ErrorException( "PHP $levelName: $message", 0, $level, $file, $line );
+		self::logError( $e, 'error', $severity );
+
+		// If $wgPropagateErrors is true return false so PHP shows/logs the error normally.
+		// Ignore $wgPropagateErrors if the error should break execution, or track_errors is set
+		// (which means someone is counting on regular PHP error handling behavior).
+		return !( $wgPropagateErrors || $level == E_RECOVERABLE_ERROR || ini_get( 'track_errors' ) );
+	}
+
+	/**
+	 * Dual purpose callback used as both a set_error_handler() callback and
+	 * a registered shutdown function. Receive a callback from the interpreter
+	 * for a raised error or system shutdown, check for a fatal error, and log
+	 * to the 'fatal' logging channel.
+	 *
+	 * Special handling is included for missing class errors as they may
+	 * indicate that the user needs to install 3rd-party libraries via
+	 * Composer or other means.
+	 *
+	 * @since 1.25
+	 *
+	 * @param int $level Error level raised
+	 * @param string $message Error message
+	 * @param string $file File that error was raised in
+	 * @param int $line Line number error was raised at
+	 * @param array $context Active symbol table point of error
+	 * @param array $trace Backtrace at point of error (undocumented HHVM
+	 *     feature)
+	 * @return bool Always returns false
+	 */
+	public static function handleFatalError(
+		$level = null, $message = null, $file = null, $line = null,
+		$context = null, $trace = null
+	) {
+		// Free reserved memory so that we have space to process OOM
+		// errors
+		self::$reservedMemory = null;
+
+		if ( $level === null ) {
+			// Called as a shutdown handler, get data from error_get_last()
+			if ( static::$handledFatalCallback ) {
+				// Already called once (probably as an error handler callback
+				// under HHVM) so don't log again.
+				return false;
+			}
+
+			$lastError = error_get_last();
+			if ( $lastError !== null ) {
+				$level = $lastError['type'];
+				$message = $lastError['message'];
+				$file = $lastError['file'];
+				$line = $lastError['line'];
+			} else {
+				$level = 0;
+				$message = '';
+			}
+		}
+
+		if ( !in_array( $level, self::$fatalErrorTypes ) ) {
+			// Only interested in fatal errors, others should have been
+			// handled by MWExceptionHandler::handleError
+			return false;
+		}
+
+		$url = WebRequest::getGlobalRequestURL();
+		$msgParts = [
+			'[{exception_id}] {exception_url}   PHP Fatal Error',
+			( $line || $file ) ? ' from' : '',
+			$line ? " line $line" : '',
+			( $line && $file ) ? ' of' : '',
+			$file ? " $file" : '',
+			": $message",
+		];
+		$msg = implode( '', $msgParts );
+
+		// Look at message to see if this is a class not found failure
+		// HHVM: Class undefined: foo
+		// PHP5: Class 'foo' not found
+		if ( preg_match( "/Class (undefined: \w+|'\w+' not found)/", $message ) ) {
+			// phpcs:disable Generic.Files.LineLength
+			$msg = <<<TXT
+{$msg}
+
+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.
+
+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.
+TXT;
+			// phpcs:enable
+		}
+
+		// We can't just create an exception and log it as it is likely that
+		// the interpreter has unwound the stack already. If that is true the
+		// stacktrace we would get would be functionally empty. If however we
+		// have been called as an error handler callback *and* HHVM is in use
+		// we will have been provided with a useful stacktrace that we can
+		// log.
+		$trace = $trace ?: debug_backtrace();
+		$logger = LoggerFactory::getInstance( 'fatal' );
+		$logger->error( $msg, [
+			'fatal_exception' => [
+				'class' => ErrorException::class,
+				'message' => "PHP Fatal Error: {$message}",
+				'code' => $level,
+				'file' => $file,
+				'line' => $line,
+				'trace' => self::prettyPrintTrace( self::redactTrace( $trace ) ),
+			],
+			'exception_id' => WebRequest::getRequestId(),
+			'exception_url' => $url,
+			'caught_by' => self::CAUGHT_BY_HANDLER
+		] );
+
+		// Remember call so we don't double process via HHVM's fatal
+		// notifications and the shutdown hook behavior
+		static::$handledFatalCallback = true;
+		return false;
+	}
+
+	/**
+	 * Generate a string representation of an exception's stack trace
+	 *
+	 * Like Exception::getTraceAsString, but replaces argument values with
+	 * argument type or class name.
+	 *
+	 * @param Exception|Throwable $e
+	 * @return string
+	 * @see prettyPrintTrace()
+	 */
+	public static function getRedactedTraceAsString( $e ) {
+		return self::prettyPrintTrace( self::getRedactedTrace( $e ) );
+	}
+
+	/**
+	 * Generate a string representation of a stacktrace.
+	 *
+	 * @param array $trace
+	 * @param string $pad Constant padding to add to each line of trace
+	 * @return string
+	 * @since 1.26
+	 */
+	public static function prettyPrintTrace( array $trace, $pad = '' ) {
+		$text = '';
+
+		$level = 0;
+		foreach ( $trace as $level => $frame ) {
+			if ( isset( $frame['file'] ) && isset( $frame['line'] ) ) {
+				$text .= "{$pad}#{$level} {$frame['file']}({$frame['line']}): ";
+			} else {
+				// 'file' and 'line' are unset for calls via call_user_func
+				// (T57634) This matches behaviour of
+				// Exception::getTraceAsString to instead display "[internal
+				// function]".
+				$text .= "{$pad}#{$level} [internal function]: ";
+			}
+
+			if ( isset( $frame['class'] ) && isset( $frame['type'] ) && isset( $frame['function'] ) ) {
+				$text .= $frame['class'] . $frame['type'] . $frame['function'];
+			} elseif ( isset( $frame['function'] ) ) {
+				$text .= $frame['function'];
+			} else {
+				$text .= 'NO_FUNCTION_GIVEN';
+			}
+
+			if ( isset( $frame['args'] ) ) {
+				$text .= '(' . implode( ', ', $frame['args'] ) . ")\n";
+			} else {
+				$text .= "()\n";
+			}
+		}
+
+		$level = $level + 1;
+		$text .= "{$pad}#{$level} {main}";
+
+		return $text;
+	}
+
+	/**
+	 * Return a copy of an exception's backtrace as an array.
+	 *
+	 * Like Exception::getTrace, but replaces each element in each frame's
+	 * argument array with the name of its class (if the element is an object)
+	 * or its type (if the element is a PHP primitive).
+	 *
+	 * @since 1.22
+	 * @param Exception|Throwable $e
+	 * @return array
+	 */
+	public static function getRedactedTrace( $e ) {
+		return static::redactTrace( $e->getTrace() );
+	}
+
+	/**
+	 * Redact a stacktrace generated by Exception::getTrace(),
+	 * debug_backtrace() or similar means. Replaces each element in each
+	 * frame's argument array with the name of its class (if the element is an
+	 * object) or its type (if the element is a PHP primitive).
+	 *
+	 * @since 1.26
+	 * @param array $trace Stacktrace
+	 * @return array Stacktrace with arugment values converted to data types
+	 */
+	public static function redactTrace( array $trace ) {
+		return array_map( function ( $frame ) {
+			if ( isset( $frame['args'] ) ) {
+				$frame['args'] = array_map( function ( $arg ) {
+					return is_object( $arg ) ? get_class( $arg ) : gettype( $arg );
+				}, $frame['args'] );
+			}
+			return $frame;
+		}, $trace );
+	}
+
+	/**
+	 * Get the ID for this exception.
+	 *
+	 * The ID is saved so that one can match the one output to the user (when
+	 * $wgShowExceptionDetails is set to false), to the entry in the debug log.
+	 *
+	 * @since 1.22
+	 * @deprecated since 1.27: Exception IDs are synonymous with request IDs.
+	 * @param Exception|Throwable $e
+	 * @return string
+	 */
+	public static function getLogId( $e ) {
+		wfDeprecated( __METHOD__, '1.27' );
+		return WebRequest::getRequestId();
+	}
+
+	/**
+	 * If the exception occurred in the course of responding to a request,
+	 * returns the requested URL. Otherwise, returns false.
+	 *
+	 * @since 1.23
+	 * @return string|false
+	 */
+	public static function getURL() {
+		global $wgRequest;
+		if ( !isset( $wgRequest ) || $wgRequest instanceof FauxRequest ) {
+			return false;
+		}
+		return $wgRequest->getRequestURL();
+	}
+
+	/**
+	 * Get a message formatting the exception message and its origin.
+	 *
+	 * @since 1.22
+	 * @param Exception|Throwable $e
+	 * @return string
+	 */
+	public static function getLogMessage( $e ) {
+		$id = WebRequest::getRequestId();
+		$type = get_class( $e );
+		$file = $e->getFile();
+		$line = $e->getLine();
+		$message = $e->getMessage();
+		$url = self::getURL() ?: '[no req]';
+
+		return "[$id] $url   $type from line $line of $file: $message";
+	}
+
+	/**
+	 * Get a normalised message for formatting with PSR-3 log event context.
+	 *
+	 * Must be used together with `getLogContext()` to be useful.
+	 *
+	 * @since 1.30
+	 * @param Exception|Throwable $e
+	 * @return string
+	 */
+	public static function getLogNormalMessage( $e ) {
+		$type = get_class( $e );
+		$file = $e->getFile();
+		$line = $e->getLine();
+		$message = $e->getMessage();
+
+		return "[{exception_id}] {exception_url}   $type from line $line of $file: $message";
+	}
+
+	/**
+	 * @param Exception|Throwable $e
+	 * @return string
+	 */
+	public static function getPublicLogMessage( $e ) {
+		$reqId = WebRequest::getRequestId();
+		$type = get_class( $e );
+		return '[' . $reqId . '] '
+			. gmdate( 'Y-m-d H:i:s' ) . ': '
+			. 'Fatal exception of type "' . $type . '"';
+	}
+
+	/**
+	 * Get a PSR-3 log event context from an Exception.
+	 *
+	 * Creates a structured array containing information about the provided
+	 * exception that can be used to augment a log message sent to a PSR-3
+	 * logger.
+	 *
+	 * @param Exception|Throwable $e
+	 * @param string $catcher CAUGHT_BY_* class constant indicating what caught the error
+	 * @return array
+	 */
+	public static function getLogContext( $e, $catcher = self::CAUGHT_BY_OTHER ) {
+		return [
+			'exception' => $e,
+			'exception_id' => WebRequest::getRequestId(),
+			'exception_url' => self::getURL() ?: '[no req]',
+			'caught_by' => $catcher
+		];
+	}
+
+	/**
+	 * Get a structured representation of an Exception.
+	 *
+	 * Returns an array of structured data (class, message, code, file,
+	 * backtrace) derived from the given exception. The backtrace information
+	 * will be redacted as per getRedactedTraceAsArray().
+	 *
+	 * @param Exception|Throwable $e
+	 * @param string $catcher CAUGHT_BY_* class constant indicating what caught the error
+	 * @return array
+	 * @since 1.26
+	 */
+	public static function getStructuredExceptionData( $e, $catcher = self::CAUGHT_BY_OTHER ) {
+		global $wgLogExceptionBacktrace;
+
+		$data = [
+			'id' => WebRequest::getRequestId(),
+			'type' => get_class( $e ),
+			'file' => $e->getFile(),
+			'line' => $e->getLine(),
+			'message' => $e->getMessage(),
+			'code' => $e->getCode(),
+			'url' => self::getURL() ?: null,
+			'caught_by' => $catcher
+		];
+
+		if ( $e instanceof ErrorException &&
+			( error_reporting() & $e->getSeverity() ) === 0
+		) {
+			// Flag surpressed errors
+			$data['suppressed'] = true;
+		}
+
+		if ( $wgLogExceptionBacktrace ) {
+			$data['backtrace'] = self::getRedactedTrace( $e );
+		}
+
+		$previous = $e->getPrevious();
+		if ( $previous !== null ) {
+			$data['previous'] = self::getStructuredExceptionData( $previous, $catcher );
+		}
+
+		return $data;
+	}
+
+	/**
+	 * Serialize an Exception object to JSON.
+	 *
+	 * The JSON object will have keys 'id', 'file', 'line', 'message', and
+	 * 'url'. These keys map to string values, with the exception of 'line',
+	 * which is a number, and 'url', which may be either a string URL or or
+	 * null if the exception did not occur in the context of serving a web
+	 * request.
+	 *
+	 * If $wgLogExceptionBacktrace is true, it will also have a 'backtrace'
+	 * key, mapped to the array return value of Exception::getTrace, but with
+	 * each element in each frame's "args" array (if set) replaced with the
+	 * argument's class name (if the argument is an object) or type name (if
+	 * the argument is a PHP primitive).
+	 *
+	 * @par Sample JSON record ($wgLogExceptionBacktrace = false):
+	 * @code
+	 *  {
+	 *    "id": "c41fb419",
+	 *    "type": "MWException",
+	 *    "file": "/var/www/mediawiki/includes/cache/MessageCache.php",
+	 *    "line": 704,
+	 *    "message": "Non-string key given",
+	 *    "url": "/wiki/Main_Page"
+	 *  }
+	 * @endcode
+	 *
+	 * @par Sample JSON record ($wgLogExceptionBacktrace = true):
+	 * @code
+	 *  {
+	 *    "id": "dc457938",
+	 *    "type": "MWException",
+	 *    "file": "/vagrant/mediawiki/includes/cache/MessageCache.php",
+	 *    "line": 704,
+	 *    "message": "Non-string key given",
+	 *    "url": "/wiki/Main_Page",
+	 *    "backtrace": [{
+	 *      "file": "/vagrant/mediawiki/extensions/VisualEditor/VisualEditor.hooks.php",
+	 *      "line": 80,
+	 *      "function": "get",
+	 *      "class": "MessageCache",
+	 *      "type": "->",
+	 *      "args": ["array"]
+	 *    }]
+	 *  }
+	 * @endcode
+	 *
+	 * @since 1.23
+	 * @param Exception|Throwable $e
+	 * @param bool $pretty Add non-significant whitespace to improve readability (default: false).
+	 * @param int $escaping Bitfield consisting of FormatJson::.*_OK class constants.
+	 * @param string $catcher CAUGHT_BY_* class constant indicating what caught the error
+	 * @return string|false JSON string if successful; false upon failure
+	 */
+	public static function jsonSerializeException(
+		$e, $pretty = false, $escaping = 0, $catcher = self::CAUGHT_BY_OTHER
+	) {
+		return FormatJson::encode(
+			self::getStructuredExceptionData( $e, $catcher ),
+			$pretty,
+			$escaping
+		);
+	}
+
+	/**
+	 * Log an exception to the exception log (if enabled).
+	 *
+	 * This method must not assume the exception is an MWException,
+	 * it is also used to handle PHP exceptions or exceptions from other libraries.
+	 *
+	 * @since 1.22
+	 * @param Exception|Throwable $e
+	 * @param string $catcher CAUGHT_BY_* class constant indicating what caught the error
+	 */
+	public static function logException( $e, $catcher = self::CAUGHT_BY_OTHER ) {
+		if ( !( $e instanceof MWException ) || $e->isLoggable() ) {
+			$logger = LoggerFactory::getInstance( 'exception' );
+			$logger->error(
+				self::getLogNormalMessage( $e ),
+				self::getLogContext( $e, $catcher )
+			);
+
+			$json = self::jsonSerializeException( $e, false, FormatJson::ALL_OK, $catcher );
+			if ( $json !== false ) {
+				$logger = LoggerFactory::getInstance( 'exception-json' );
+				$logger->error( $json, [ 'private' => true ] );
+			}
+
+			Hooks::run( 'LogException', [ $e, false ] );
+		}
+	}
+
+	/**
+	 * Log an exception that wasn't thrown but made to wrap an error.
+	 *
+	 * @since 1.25
+	 * @param ErrorException $e
+	 * @param string $channel
+	 * @param string $level
+	 */
+	protected static function logError(
+		ErrorException $e, $channel, $level = LogLevel::ERROR
+	) {
+		$catcher = self::CAUGHT_BY_HANDLER;
+		// The set_error_handler callback is independent from error_reporting.
+		// Filter out unwanted errors manually (e.g. when
+		// Wikimedia\suppressWarnings is active).
+		$suppressed = ( error_reporting() & $e->getSeverity() ) === 0;
+		if ( !$suppressed ) {
+			$logger = LoggerFactory::getInstance( $channel );
+			$logger->log(
+				$level,
+				self::getLogNormalMessage( $e ),
+				self::getLogContext( $e, $catcher )
+			);
+		}
+
+		// Include all errors in the json log (surpressed errors will be flagged)
+		$json = self::jsonSerializeException( $e, false, FormatJson::ALL_OK, $catcher );
+		if ( $json !== false ) {
+			$logger = LoggerFactory::getInstance( "{$channel}-json" );
+			$logger->log( $level, $json, [ 'private' => true ] );
+		}
+
+		Hooks::run( 'LogException', [ $e, $suppressed ] );
+	}
+}
diff --git a/www/wiki/includes/exception/MWExceptionRenderer.php b/www/wiki/includes/exception/MWExceptionRenderer.php
new file mode 100644
index 00000000..5d750365
--- /dev/null
+++ b/www/wiki/includes/exception/MWExceptionRenderer.php
@@ -0,0 +1,338 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+use Wikimedia\Rdbms\DBConnectionError;
+use Wikimedia\Rdbms\DBError;
+use Wikimedia\Rdbms\DBReadOnlyError;
+use Wikimedia\Rdbms\DBExpectedError;
+
+/**
+ * Class to expose exceptions to the client (API bots, users, admins using CLI scripts)
+ * @since 1.28
+ */
+class MWExceptionRenderer {
+	const AS_RAW = 1; // show as text
+	const AS_PRETTY = 2; // show as HTML
+
+	/**
+	 * @param Exception|Throwable $e Original exception
+	 * @param int $mode MWExceptionExposer::AS_* constant
+	 * @param Exception|Throwable|null $eNew New exception from attempting to show the first
+	 */
+	public static function output( $e, $mode, $eNew = null ) {
+		global $wgMimeType;
+
+		if ( defined( 'MW_API' ) ) {
+			// Unhandled API exception, we can't be sure that format printer is alive
+			self::header( 'MediaWiki-API-Error: internal_api_error_' . get_class( $e ) );
+			wfHttpError( 500, 'Internal Server Error', self::getText( $e ) );
+		} elseif ( self::isCommandLine() ) {
+			self::printError( self::getText( $e ) );
+		} elseif ( $mode === self::AS_PRETTY ) {
+			self::statusHeader( 500 );
+			self::header( "Content-Type: $wgMimeType; charset=utf-8" );
+			if ( $e instanceof DBConnectionError ) {
+				self::reportOutageHTML( $e );
+			} else {
+				self::reportHTML( $e );
+			}
+		} else {
+			self::statusHeader( 500 );
+			self::header( "Content-Type: $wgMimeType; charset=utf-8" );
+			if ( $eNew ) {
+				$message = "MediaWiki internal error.\n\n";
+				if ( self::showBackTrace( $e ) ) {
+					$message .= 'Original exception: ' .
+						MWExceptionHandler::getLogMessage( $e ) .
+						"\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $e ) .
+						"\n\nException caught inside exception handler: " .
+							MWExceptionHandler::getLogMessage( $eNew ) .
+						"\nBacktrace:\n" . MWExceptionHandler::getRedactedTraceAsString( $eNew );
+				} else {
+					$message .= 'Original exception: ' .
+						MWExceptionHandler::getPublicLogMessage( $e );
+					$message .= "\n\nException caught inside exception handler.\n\n" .
+						self::getShowBacktraceError( $e );
+				}
+				$message .= "\n";
+			} else {
+				if ( self::showBackTrace( $e ) ) {
+					$message = MWExceptionHandler::getLogMessage( $e ) .
+						"\nBacktrace:\n" .
+						MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
+				} else {
+					$message = MWExceptionHandler::getPublicLogMessage( $e );
+				}
+			}
+			echo nl2br( htmlspecialchars( $message ) ) . "\n";
+		}
+	}
+
+	/**
+	 * @param Exception|Throwable $e
+	 * @return bool Should the exception use $wgOut to output the error?
+	 */
+	private static function useOutputPage( $e ) {
+		// Can the extension use the Message class/wfMessage to get i18n-ed messages?
+		foreach ( $e->getTrace() as $frame ) {
+			if ( isset( $frame['class'] ) && $frame['class'] === LocalisationCache::class ) {
+				return false;
+			}
+		}
+
+		// Don't even bother with OutputPage if there's no Title context set,
+		// (e.g. we're in RL code on load.php) - the Skin system (and probably
+		// most of MediaWiki) won't work.
+
+		return (
+			!empty( $GLOBALS['wgFullyInitialised'] ) &&
+			!empty( $GLOBALS['wgOut'] ) &&
+			RequestContext::getMain()->getTitle() &&
+			!defined( 'MEDIAWIKI_INSTALL' )
+		);
+	}
+
+	/**
+	 * Output the exception report using HTML
+	 *
+	 * @param Exception|Throwable $e
+	 */
+	private static function reportHTML( $e ) {
+		global $wgOut, $wgSitename;
+
+		if ( self::useOutputPage( $e ) ) {
+			if ( $e instanceof MWException ) {
+				$wgOut->prepareErrorPage( $e->getPageTitle() );
+			} elseif ( $e instanceof DBReadOnlyError ) {
+				$wgOut->prepareErrorPage( self::msg( 'readonly', 'Database is locked' ) );
+			} elseif ( $e instanceof DBExpectedError ) {
+				$wgOut->prepareErrorPage( self::msg( 'databaseerror', 'Database error' ) );
+			} else {
+				$wgOut->prepareErrorPage( self::msg( 'internalerror', 'Internal error' ) );
+			}
+
+			// Show any custom GUI message before the details
+			if ( $e instanceof MessageSpecifier ) {
+				$wgOut->addHTML( Html::element( 'p', [], Message::newFromSpecifier( $e )->text() ) );
+			}
+			$wgOut->addHTML( self::getHTML( $e ) );
+
+			$wgOut->output();
+		} else {
+			self::header( 'Content-Type: text/html; charset=utf-8' );
+			$pageTitle = self::msg( 'internalerror', 'Internal error' );
+			echo "<!DOCTYPE html>\n" .
+				'<html><head>' .
+				// Mimick OutputPage::setPageTitle behaviour
+				'<title>' .
+				htmlspecialchars( self::msg( 'pagetitle', "$1 - $wgSitename", $pageTitle ) ) .
+				'</title>' .
+				'<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
+				"</head><body>\n";
+
+			echo self::getHTML( $e );
+
+			echo "</body></html>\n";
+		}
+	}
+
+	/**
+	 * If $wgShowExceptionDetails is true, return a HTML message with a
+	 * backtrace to the error, otherwise show a message to ask to set it to true
+	 * to show that information.
+	 *
+	 * @param Exception|Throwable $e
+	 * @return string Html to output
+	 */
+	public static function getHTML( $e ) {
+		if ( self::showBackTrace( $e ) ) {
+			$html = "<div class=\"errorbox mw-content-ltr\"><p>" .
+				nl2br( htmlspecialchars( MWExceptionHandler::getLogMessage( $e ) ) ) .
+				'</p><p>Backtrace:</p><p>' .
+				nl2br( htmlspecialchars( MWExceptionHandler::getRedactedTraceAsString( $e ) ) ) .
+				"</p></div>\n";
+		} else {
+			$logId = WebRequest::getRequestId();
+			$html = "<div class=\"errorbox mw-content-ltr\">" .
+				htmlspecialchars(
+					'[' . $logId . '] ' .
+					gmdate( 'Y-m-d H:i:s' ) . ": " .
+					self::msg( "internalerror-fatal-exception",
+						"Fatal exception of type $1",
+						get_class( $e ),
+						$logId,
+						MWExceptionHandler::getURL()
+				) ) . "</div>\n" .
+				"<!-- " . wordwrap( self::getShowBacktraceError( $e ), 50 ) . " -->";
+		}
+
+		return $html;
+	}
+
+	/**
+	 * Get a message from i18n
+	 *
+	 * @param string $key Message name
+	 * @param string $fallback Default message if the message cache can't be
+	 *                  called by the exception
+	 * The function also has other parameters that are arguments for the message
+	 * @return string Message with arguments replaced
+	 */
+	private static function msg( $key, $fallback /*[, params...] */ ) {
+		$args = array_slice( func_get_args(), 2 );
+		try {
+			return wfMessage( $key, $args )->text();
+		} catch ( Exception $e ) {
+			return wfMsgReplaceArgs( $fallback, $args );
+		}
+	}
+
+	/**
+	 * @param Exception|Throwable $e
+	 * @return string
+	 */
+	private static function getText( $e ) {
+		if ( self::showBackTrace( $e ) ) {
+			return MWExceptionHandler::getLogMessage( $e ) .
+				"\nBacktrace:\n" .
+				MWExceptionHandler::getRedactedTraceAsString( $e ) . "\n";
+		} else {
+			return self::getShowBacktraceError( $e ) . "\n";
+		}
+	}
+
+	/**
+	 * @param Exception|Throwable $e
+	 * @return bool
+	 */
+	private static function showBackTrace( $e ) {
+		global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
+
+		return (
+			$wgShowExceptionDetails &&
+			( !( $e instanceof DBError ) || $wgShowDBErrorBacktrace )
+		);
+	}
+
+	/**
+	 * @param Exception|Throwable $e
+	 * @return string
+	 */
+	private static function getShowBacktraceError( $e ) {
+		global $wgShowExceptionDetails, $wgShowDBErrorBacktrace;
+		$vars = [];
+		if ( !$wgShowExceptionDetails ) {
+			$vars[] = '$wgShowExceptionDetails = true;';
+		}
+		if ( $e instanceof DBError && !$wgShowDBErrorBacktrace ) {
+			$vars[] = '$wgShowDBErrorBacktrace = true;';
+		}
+		$vars = implode( ' and ', $vars );
+		return "Set $vars at the bottom of LocalSettings.php to show detailed debugging information.";
+	}
+
+	/**
+	 * @return bool
+	 */
+	private static function isCommandLine() {
+		return !empty( $GLOBALS['wgCommandLineMode'] );
+	}
+
+	/**
+	 * @param string $header
+	 */
+	private static function header( $header ) {
+		if ( !headers_sent() ) {
+			header( $header );
+		}
+	}
+
+	/**
+	 * @param int $code
+	 */
+	private static function statusHeader( $code ) {
+		if ( !headers_sent() ) {
+			HttpStatus::header( $code );
+		}
+	}
+
+	/**
+	 * Print a message, if possible to STDERR.
+	 * Use this in command line mode only (see isCommandLine)
+	 *
+	 * @param string $message Failure text
+	 */
+	private static function printError( $message ) {
+		// NOTE: STDERR may not be available, especially if php-cgi is used from the
+		// command line (bug #15602). Try to produce meaningful output anyway. Using
+		// echo may corrupt output to STDOUT though.
+		if ( defined( 'STDERR' ) ) {
+			fwrite( STDERR, $message );
+		} else {
+			echo $message;
+		}
+	}
+
+	/**
+	 * @param Exception|Throwable $e
+	 */
+	private static function reportOutageHTML( $e ) {
+		global $wgShowDBErrorBacktrace, $wgShowHostnames, $wgShowSQLErrors, $wgSitename;
+
+		$sorry = htmlspecialchars( self::msg(
+			'dberr-problems',
+			'Sorry! This site is experiencing technical difficulties.'
+		) );
+		$again = htmlspecialchars( self::msg(
+			'dberr-again',
+			'Try waiting a few minutes and reloading.'
+		) );
+
+		if ( $wgShowHostnames || $wgShowSQLErrors ) {
+			$info = str_replace(
+				'$1',
+				Html::element( 'span', [ 'dir' => 'ltr' ], $e->getMessage() ),
+				htmlspecialchars( self::msg( 'dberr-info', '($1)' ) )
+			);
+		} else {
+			$info = htmlspecialchars( self::msg(
+				'dberr-info-hidden',
+				'(Cannot access the database)'
+			) );
+		}
+
+		MessageCache::singleton()->disable(); // no DB access
+		$html = "<!DOCTYPE html>\n" .
+				'<html><head>' .
+				'<title>' .
+				htmlspecialchars( $wgSitename ) .
+				'</title>' .
+				'<style>body { font-family: sans-serif; margin: 0; padding: 0.5em 2em; }</style>' .
+				"</head><body><h1>$sorry</h1><p>$again</p><p><small>$info</small></p>";
+
+		if ( $wgShowDBErrorBacktrace ) {
+			$html .= '<p>Backtrace:</p><pre>' .
+				htmlspecialchars( $e->getTraceAsString() ) . '</pre>';
+		}
+
+		$html .= '</body></html>';
+		echo $html;
+	}
+}
diff --git a/www/wiki/includes/exception/MWUnknownContentModelException.php b/www/wiki/includes/exception/MWUnknownContentModelException.php
new file mode 100644
index 00000000..df7111ac
--- /dev/null
+++ b/www/wiki/includes/exception/MWUnknownContentModelException.php
@@ -0,0 +1,25 @@
+<?php
+/**
+ * Exception thrown when an unregistered content model is requested. This error
+ * can be triggered by user input, so a separate exception class is provided so
+ * callers can substitute a context-specific, internationalised error message.
+ *
+ * @ingroup Content
+ * @since 1.27
+ */
+class MWUnknownContentModelException extends MWException {
+	/** @var string The name of the unknown content model */
+	private $modelId;
+
+	/** @param string $modelId */
+	function __construct( $modelId ) {
+		parent::__construct( "The content model '$modelId' is not registered on this wiki.\n" .
+			'See https://www.mediawiki.org/wiki/Content_handlers to find out which extensions ' .
+			'handle this content model.' );
+		$this->modelId = $modelId;
+	}
+	/** @return string */
+	public function getModelId() {
+		return $this->modelId;
+	}
+}
diff --git a/www/wiki/includes/exception/PermissionsError.php b/www/wiki/includes/exception/PermissionsError.php
new file mode 100644
index 00000000..cc69a762
--- /dev/null
+++ b/www/wiki/includes/exception/PermissionsError.php
@@ -0,0 +1,72 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Show an error when a user tries to do something they do not have the necessary
+ * permissions for.
+ *
+ * @since 1.18
+ * @ingroup Exception
+ */
+class PermissionsError extends ErrorPageError {
+	public $permission, $errors;
+
+	/**
+	 * @param string|null $permission A permission name or null if unknown
+	 * @param array $errors Error message keys or [key, param...] arrays; must not be empty if
+	 *   $permission is null
+	 * @throws \InvalidArgumentException
+	 */
+	public function __construct( $permission, $errors = [] ) {
+		global $wgLang;
+
+		if ( $permission === null && !$errors ) {
+			throw new \InvalidArgumentException( __METHOD__ .
+				': $permission and $errors cannot both be empty' );
+		}
+
+		$this->permission = $permission;
+
+		if ( !count( $errors ) ) {
+			$groups = [];
+			foreach ( User::getGroupsWithPermission( $this->permission ) as $group ) {
+				$groups[] = UserGroupMembership::getLink( $group, RequestContext::getMain(), 'wiki' );
+			}
+
+			if ( $groups ) {
+				$errors[] = [ 'badaccess-groups', $wgLang->commaList( $groups ), count( $groups ) ];
+			} else {
+				$errors[] = [ 'badaccess-group0' ];
+			}
+		}
+
+		$this->errors = $errors;
+
+		// Give the parent class something to work with
+		parent::__construct( 'permissionserrors', Message::newFromSpecifier( $errors[0] ) );
+	}
+
+	public function report() {
+		global $wgOut;
+
+		$wgOut->showPermissionsErrorPage( $this->errors, $this->permission );
+		$wgOut->output();
+	}
+}
diff --git a/www/wiki/includes/exception/ProcOpenError.php b/www/wiki/includes/exception/ProcOpenError.php
new file mode 100644
index 00000000..f00bcd4b
--- /dev/null
+++ b/www/wiki/includes/exception/ProcOpenError.php
@@ -0,0 +1,29 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+namespace MediaWiki;
+
+use Exception;
+
+class ProcOpenError extends Exception {
+	public function __construct() {
+		parent::__construct( 'proc_open() returned error!' );
+	}
+}
diff --git a/www/wiki/includes/exception/ReadOnlyError.php b/www/wiki/includes/exception/ReadOnlyError.php
new file mode 100644
index 00000000..de42f056
--- /dev/null
+++ b/www/wiki/includes/exception/ReadOnlyError.php
@@ -0,0 +1,36 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Show an error when the wiki is locked/read-only and the user tries to do
+ * something that requires write access.
+ *
+ * @since 1.18
+ * @ingroup Exception
+ */
+class ReadOnlyError extends ErrorPageError {
+	public function __construct() {
+		parent::__construct(
+			'readonly',
+			'readonlytext',
+			wfReadOnlyReason() ?: []
+		);
+	}
+}
diff --git a/www/wiki/includes/exception/ShellDisabledError.php b/www/wiki/includes/exception/ShellDisabledError.php
new file mode 100644
index 00000000..203b58dc
--- /dev/null
+++ b/www/wiki/includes/exception/ShellDisabledError.php
@@ -0,0 +1,32 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+namespace MediaWiki;
+
+use Exception;
+
+/**
+ * @since 1.30
+ */
+class ShellDisabledError extends Exception {
+	public function __construct() {
+		parent::__construct( 'Unable to run external programs, proc_open() is disabled' );
+	}
+}
diff --git a/www/wiki/includes/exception/ThrottledError.php b/www/wiki/includes/exception/ThrottledError.php
new file mode 100644
index 00000000..bec0d904
--- /dev/null
+++ b/www/wiki/includes/exception/ThrottledError.php
@@ -0,0 +1,40 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Show an error when the user hits a rate limit.
+ *
+ * @since 1.18
+ * @ingroup Exception
+ */
+class ThrottledError extends ErrorPageError {
+	public function __construct() {
+		parent::__construct(
+			'actionthrottled',
+			'actionthrottledtext'
+		);
+	}
+
+	public function report() {
+		global $wgOut;
+		$wgOut->setStatusCode( 429 );
+		parent::report();
+	}
+}
diff --git a/www/wiki/includes/exception/UserBlockedError.php b/www/wiki/includes/exception/UserBlockedError.php
new file mode 100644
index 00000000..9d19f8b6
--- /dev/null
+++ b/www/wiki/includes/exception/UserBlockedError.php
@@ -0,0 +1,33 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Show an error when the user tries to do something whilst blocked.
+ *
+ * @since 1.18
+ * @ingroup Exception
+ */
+class UserBlockedError extends ErrorPageError {
+	public function __construct( Block $block ) {
+		// @todo FIXME: Implement a more proper way to get context here.
+		$params = $block->getPermissionsError( RequestContext::getMain() );
+		parent::__construct( 'blockedtitle', array_shift( $params ), $params );
+	}
+}
diff --git a/www/wiki/includes/exception/UserNotLoggedIn.php b/www/wiki/includes/exception/UserNotLoggedIn.php
new file mode 100644
index 00000000..6086d559
--- /dev/null
+++ b/www/wiki/includes/exception/UserNotLoggedIn.php
@@ -0,0 +1,104 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Redirect a user to the login page
+ *
+ * This is essentially an ErrorPageError exception which by default uses the
+ * 'exception-nologin' as a title and 'exception-nologin-text' for the message.
+ *
+ * @note In order for this exception to redirect, the error message passed to the
+ * constructor has to be explicitly added to LoginHelper::validErrorMessages or with
+ * the LoginFormValidErrorMessages hook. Otherwise, the user will just be shown the message
+ * rather than redirected.
+ *
+ * @par Example:
+ * @code
+ * if( $user->isAnon() ) {
+ *   throw new UserNotLoggedIn();
+ * }
+ * @endcode
+ *
+ * Note the parameter order differs from ErrorPageError, this allows you to
+ * simply specify a reason without overriding the default title.
+ *
+ * @par Example:
+ * @code
+ * if( $user->isAnon() ) {
+ *   throw new UserNotLoggedIn( 'action-require-loggedin' );
+ * }
+ * @endcode
+ *
+ * @see T39627
+ * @since 1.20
+ * @ingroup Exception
+ */
+class UserNotLoggedIn extends ErrorPageError {
+
+	/**
+	 * @note The value of the $reasonMsg parameter must be put into LoginForm::validErrorMessages or
+	 * set with the LoginFormValidErrorMessages Hook.
+	 * if you want the user to be automatically redirected to the login form.
+	 *
+	 * @param string $reasonMsg A message key containing the reason for the error.
+	 *        Optional, default: 'exception-nologin-text'
+	 * @param string $titleMsg A message key to set the page title.
+	 *        Optional, default: 'exception-nologin'
+	 * @param array $params Parameters to wfMessage().
+	 *        Optional, default: []
+	 */
+	public function __construct(
+		$reasonMsg = 'exception-nologin-text',
+		$titleMsg = 'exception-nologin',
+		$params = []
+	) {
+		parent::__construct( $titleMsg, $reasonMsg, $params );
+	}
+
+	/**
+	 * Redirect to Special:Userlogin if the specified message is compatible. Otherwise,
+	 * show an error page as usual.
+	 */
+	public function report() {
+		// If an unsupported message is used, don't try redirecting to Special:Userlogin,
+		// since the message may not be compatible.
+		if ( !in_array( $this->msg, LoginHelper::getValidErrorMessages() ) ) {
+			parent::report();
+		}
+
+		// Message is valid. Redirec to Special:Userlogin
+
+		$context = RequestContext::getMain();
+
+		$output = $context->getOutput();
+		$query = $context->getRequest()->getValues();
+		// Title will be overridden by returnto
+		unset( $query['title'] );
+		// Redirect to Special:Userlogin
+		$output->redirect( SpecialPage::getTitleFor( 'Userlogin' )->getFullURL( [
+			// Return to this page when the user logs in
+			'returnto' => $context->getTitle()->getFullText(),
+			'returntoquery' => wfArrayToCgi( $query ),
+			'warning' => $this->msg,
+		] ) );
+
+		$output->output();
+	}
+}