Update to MediaWiki 1.24.1

11 files changed, 1151 insertions, 0 deletions

diff --git a/includes/exception/BadTitleError.php b/includes/exception/BadTitleError.php
new file mode 100644
index 00000000..e62f8bd6
--- /dev/null
+++ b/includes/exception/BadTitleError.php
@@ -0,0 +1,51 @@
+<?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.
+ * Similar to ErrorPage, but emit a 400 HTTP error code to let mobile
+ * browser it is not really a valid content.
+ *
+ * @since 1.19
+ * @ingroup Exception
+ */
+class BadTitleError extends ErrorPageError {
+	/**
+	 * @param string|Message $msg A message key (default: 'badtitletext')
+	 * @param array $params Parameter to wfMessage()
+	 */
+	public function __construct( $msg = 'badtitletext', $params = array() ) {
+		parent::__construct( 'badtitle', $msg, $params );
+	}
+
+	/**
+	 * Just like ErrorPageError::report() but additionally set
+	 * a 400 HTTP status code (bug 33646).
+	 */
+	public function report() {
+		global $wgOut;
+
+		// bug 33646: a badtitle error page need to return an error code
+		// to let mobile browser now that it is not a normal page.
+		$wgOut->setStatusCode( 400 );
+		parent::report();
+	}
+
+}
diff --git a/includes/exception/ErrorPageError.php b/includes/exception/ErrorPageError.php
new file mode 100644
index 00000000..3631a340
--- /dev/null
+++ b/includes/exception/ErrorPageError.php
@@ -0,0 +1,61 @@
+<?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 {
+	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 = array() ) {
+		$this->title = $title;
+		$this->msg = $msg;
+		$this->params = $params;
+
+		// Bug 44111: 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.
+		if ( $msg instanceof Message ) {
+			$enMsg = clone( $msg );
+		} else {
+			$enMsg = wfMessage( $msg, $params );
+		}
+		$enMsg->inLanguage( 'en' )->useDatabase( false );
+		parent::__construct( $enMsg->text() );
+	}
+
+	public function report() {
+		global $wgOut;
+
+		$wgOut->showErrorPage( $this->title, $this->msg, $this->params );
+		$wgOut->output();
+	}
+}
diff --git a/includes/exception/FatalError.php b/includes/exception/FatalError.php
new file mode 100644
index 00000000..a7d672fa
--- /dev/null
+++ b/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/includes/exception/HttpError.php b/includes/exception/HttpError.php
new file mode 100644
index 00000000..6ab6e039
--- /dev/null
+++ b/includes/exception/HttpError.php
@@ -0,0 +1,93 @@
+<?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 that looks like an HTTP server error.
+ * Replacement for wfHttpError().
+ *
+ * @since 1.19
+ * @ingroup Exception
+ */
+class HttpError extends MWException {
+	private $httpCode, $header, $content;
+
+	/**
+	 * Constructor
+	 *
+	 * @param int $httpCode HTTP status code to send to the client
+	 * @param string|Message $content Content of the message
+	 * @param string|Message $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;
+	}
+
+	/**
+	 * Returns the HTTP status code supplied to the constructor.
+	 *
+	 * @return int
+	 */
+	public function getStatusCode() {
+		return $this->httpCode;
+	}
+
+	/**
+	 * Report the HTTP error.
+	 * Sends the appropriate HTTP status code and outputs an
+	 * HTML page with an error message.
+	 */
+	public function report() {
+		$httpMessage = HttpStatus::getMessage( $this->httpCode );
+
+		header( "Status: {$this->httpCode} {$httpMessage}", true, $this->httpCode );
+		header( 'Content-type: text/html; charset=utf-8' );
+
+		print $this->getHTML();
+	}
+
+	/**
+	 * 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 ) {
+			$header = HttpStatus::getMessage( $this->httpCode );
+		} elseif ( $this->header instanceof Message ) {
+			$header = $this->header->escaped();
+		} else {
+			$header = htmlspecialchars( $this->header );
+		}
+
+		if ( $this->content instanceof Message ) {
+			$content = $this->content->escaped();
+		} else {
+			$content = htmlspecialchars( $this->content );
+		}
+
+		return "<!DOCTYPE html>\n" .
+		"<html><head><title>$header</title></head>\n" .
+		"<body><h1>$header</h1><p>$content</p></body></html>\n";
+	}
+}
diff --git a/includes/exception/MWException.php b/includes/exception/MWException.php
new file mode 100644
index 00000000..074128f8
--- /dev/null
+++ b/includes/exception/MWException.php
@@ -0,0 +1,262 @@
+<?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' ) {
+				return false;
+			}
+		}
+
+		return $wgLang instanceof Language;
+	}
+
+	/**
+	 * Run hook to allow extensions to modify the text of the exception
+	 *
+	 * @param string $name Class name of the exception
+	 * @param array $args Arguments to pass to the callback functions
+	 * @return string|null String to output or null if any hook has been called
+	 */
+	public function runHooks( $name, $args = array() ) {
+		global $wgExceptionHooks;
+
+		if ( !isset( $wgExceptionHooks ) || !is_array( $wgExceptionHooks ) ) {
+			return null; // Just silently ignore
+		}
+
+		if ( !array_key_exists( $name, $wgExceptionHooks ) ||
+			!is_array( $wgExceptionHooks[$name] )
+		) {
+			return null;
+		}
+
+		$hooks = $wgExceptionHooks[$name];
+		$callargs = array_merge( array( $this ), $args );
+
+		foreach ( $hooks as $hook ) {
+			if (
+				is_string( $hook ) ||
+				( is_array( $hook ) && count( $hook ) >= 2 && is_string( $hook[0] ) )
+			) {
+				// 'function' or array( 'class', hook' )
+				$result = call_user_func_array( $hook, $callargs );
+			} else {
+				$result = null;
+			}
+
+			if ( is_string( $result ) ) {
+				return $result;
+			}
+		}
+		return null;
+	}
+
+	/**
+	 * 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() ) {
+			return wfMessage( $key, $args )->text();
+		} else {
+			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 {
+			return "<div class=\"errorbox\">" .
+			'[' . MWExceptionHandler::getLogId( $this ) . '] ' .
+			gmdate( 'Y-m-d H:i:s' ) .
+			": Fatal exception of type " . get_class( $this ) . "</div>\n" .
+			"<!-- 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() );
+
+			$hookResult = $this->runHooks( get_class( $this ) );
+			if ( $hookResult ) {
+				$wgOut->addHTML( $hookResult );
+			} else {
+				$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";
+
+			$hookResult = $this->runHooks( get_class( $this ) . 'Raw' );
+			if ( $hookResult ) {
+				echo $hookResult;
+			} else {
+				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;
+
+		MWExceptionHandler::logException( $this );
+
+		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( $this ) );
+			wfHttpError( 500, 'Internal Server Error', $this->getText() );
+		} elseif ( self::isCommandLine() ) {
+			MWExceptionHandler::printError( $this->getText() );
+		} else {
+			self::header( 'HTTP/1.1 500 MediaWiki exception' );
+			self::header( 'Status: 500 MediaWiki exception' );
+			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 );
+		}
+	}
+}
diff --git a/includes/exception/MWExceptionHandler.php b/includes/exception/MWExceptionHandler.php
new file mode 100644
index 00000000..71917e13
--- /dev/null
+++ b/includes/exception/MWExceptionHandler.php
@@ -0,0 +1,372 @@
+<?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
+ */
+
+/**
+ * Handler class for MWExceptions
+ * @ingroup Exception
+ */
+class MWExceptionHandler {
+	/**
+	 * Install an exception handler for MediaWiki exception types.
+	 */
+	public static function installHandler() {
+		set_exception_handler( array( 'MWExceptionHandler', 'handle' ) );
+	}
+
+	/**
+	 * Report an exception to the user
+	 * @param Exception $e
+	 */
+	protected static function report( Exception $e ) {
+		global $wgShowExceptionDetails;
+
+		$cmdLine = MWException::isCommandLine();
+
+		if ( $e instanceof MWException ) {
+			try {
+				// Try and show the exception prettily, with the normal skin infrastructure
+				$e->report();
+			} catch ( Exception $e2 ) {
+				// Exception occurred from within exception handler
+				// Show a simpler error message for the original exception,
+				// don't try to invoke report()
+				$message = "MediaWiki internal error.\n\n";
+
+				if ( $wgShowExceptionDetails ) {
+					$message .= 'Original exception: ' . self::getLogMessage( $e ) .
+						"\nBacktrace:\n" . self::getRedactedTraceAsString( $e ) .
+						"\n\nException caught inside exception handler: " . self::getLogMessage( $e2 ) .
+						"\nBacktrace:\n" . self::getRedactedTraceAsString( $e2 );
+				} else {
+					$message .= "Exception caught inside exception handler.\n\n" .
+						"Set \$wgShowExceptionDetails = true; at the bottom of LocalSettings.php " .
+						"to show detailed debugging information.";
+				}
+
+				$message .= "\n";
+
+				if ( $cmdLine ) {
+					self::printError( $message );
+				} else {
+					echo nl2br( htmlspecialchars( $message ) ) . "\n";
+				}
+			}
+		} else {
+			$message = "Unexpected non-MediaWiki exception encountered, of type \"" .
+				get_class( $e ) . "\"";
+
+			if ( $wgShowExceptionDetails ) {
+				$message .= "\n" . MWExceptionHandler::getLogMessage( $e ) . "\nBacktrace:\n" .
+					self::getRedactedTraceAsString( $e ) . "\n";
+			}
+
+			if ( $cmdLine ) {
+				self::printError( $message );
+			} else {
+				echo nl2br( htmlspecialchars( $message ) ) . "\n";
+			}
+		}
+	}
+
+	/**
+	 * Print a message, if possible to STDERR.
+	 * Use this in command line mode only (see isCommandLine)
+	 *
+	 * @param string $message Failure text
+	 */
+	public 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;
+		}
+	}
+
+	/**
+	 * If there are any open database transactions, roll them back and log
+	 * the stack trace of the exception that should have been caught so the
+	 * transaction could be aborted properly.
+	 * @since 1.23
+	 * @param Exception $e
+	 */
+	public static function rollbackMasterChangesAndLog( Exception $e ) {
+		$factory = wfGetLBFactory();
+		if ( $factory->hasMasterChanges() ) {
+			wfDebugLog( 'Bug56269',
+				'Exception thrown with an uncommited database transaction: ' .
+					MWExceptionHandler::getLogMessage( $e ) . "\n" .
+					$e->getTraceAsString()
+			);
+			$factory->rollbackMasterChanges();
+		}
+	}
+
+	/**
+	 * Exception handler which simulates the appropriate catch() handling:
+	 *
+	 *   try {
+	 *       ...
+	 *   } catch ( MWException $e ) {
+	 *       $e->report();
+	 *   } catch ( Exception $e ) {
+	 *       echo $e->__toString();
+	 *   }
+	 * @param Exception $e
+	 */
+	public static function handle( $e ) {
+		global $wgFullyInitialised;
+
+		self::rollbackMasterChangesAndLog( $e );
+
+		self::report( $e );
+
+		// Final cleanup
+		if ( $wgFullyInitialised ) {
+			try {
+				// uses $wgRequest, hence the $wgFullyInitialised condition
+				wfLogProfilingData();
+			} catch ( Exception $e ) {
+			}
+		}
+
+		// Exit value should be nonzero for the benefit of shell jobs
+		exit( 1 );
+	}
+
+	/**
+	 * 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 $e
+	 * @return string
+	 */
+	public static function getRedactedTraceAsString( Exception $e ) {
+		$text = '';
+
+		foreach ( self::getRedactedTrace( $e ) as $level => $frame ) {
+			if ( isset( $frame['file'] ) && isset( $frame['line'] ) ) {
+				$text .= "#{$level} {$frame['file']}({$frame['line']}): ";
+			} else {
+				// 'file' and 'line' are unset for calls via call_user_func (bug 55634)
+				// This matches behaviour of Exception::getTraceAsString to instead
+				// display "[internal function]".
+				$text .= "#{$level} [internal function]: ";
+			}
+
+			if ( isset( $frame['class'] ) ) {
+				$text .= $frame['class'] . $frame['type'] . $frame['function'];
+			} else {
+				$text .= $frame['function'];
+			}
+
+			if ( isset( $frame['args'] ) ) {
+				$text .= '(' . implode( ', ', $frame['args'] ) . ")\n";
+			} else {
+				$text .= "()\n";
+			}
+		}
+
+		$level = $level + 1;
+		$text .= "#{$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 $e
+	 * @return array
+	 */
+	public static function getRedactedTrace( Exception $e ) {
+		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;
+		}, $e->getTrace() );
+	}
+
+	/**
+	 * Get the ID for this error.
+	 *
+	 * 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
+	 * @param Exception $e
+	 * @return string
+	 */
+	public static function getLogId( Exception $e ) {
+		if ( !isset( $e->_mwLogId ) ) {
+			$e->_mwLogId = wfRandomString( 8 );
+		}
+		return $e->_mwLogId;
+	}
+
+	/**
+	 * If the exception occurred in the course of responding to a request,
+	 * returns the requested URL. Otherwise, returns false.
+	 *
+	 * @since 1.23
+	 * @return string|bool
+	 */
+	public static function getURL() {
+		global $wgRequest;
+		if ( !isset( $wgRequest ) || $wgRequest instanceof FauxRequest ) {
+			return false;
+		}
+		return $wgRequest->getRequestURL();
+	}
+
+	/**
+	 * Return the requested URL and point to file and line number from which the
+	 * exception occurred.
+	 *
+	 * @since 1.22
+	 * @param Exception $e
+	 * @return string
+	 */
+	public static function getLogMessage( Exception $e ) {
+		$id = self::getLogId( $e );
+		$file = $e->getFile();
+		$line = $e->getLine();
+		$message = $e->getMessage();
+		$url = self::getURL() ?: '[no req]';
+
+		return "[$id] $url   Exception from line $line of $file: $message";
+	}
+
+	/**
+	 * 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",
+	 *    "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",
+	 *    "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 $e
+	 * @param bool $pretty Add non-significant whitespace to improve readability (default: false).
+	 * @param int $escaping Bitfield consisting of FormatJson::.*_OK class constants.
+	 * @return string|bool JSON string if successful; false upon failure
+	 */
+	public static function jsonSerializeException( Exception $e, $pretty = false, $escaping = 0 ) {
+		global $wgLogExceptionBacktrace;
+
+		$exceptionData = array(
+			'id' => self::getLogId( $e ),
+			'file' => $e->getFile(),
+			'line' => $e->getLine(),
+			'message' => $e->getMessage(),
+		);
+
+		// Because MediaWiki is first and foremost a web application, we set a
+		// 'url' key unconditionally, but set it to null if the exception does
+		// not occur in the context of a web request, as a way of making that
+		// fact visible and explicit.
+		$exceptionData['url'] = self::getURL() ?: null;
+
+		if ( $wgLogExceptionBacktrace ) {
+			// Argument values may not be serializable, so redact them.
+			$exceptionData['backtrace'] = self::getRedactedTrace( $e );
+		}
+
+		return FormatJson::encode( $exceptionData, $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 errors or errors from other libraries.
+	 *
+	 * @since 1.22
+	 * @param Exception $e
+	 */
+	public static function logException( Exception $e ) {
+		global $wgLogExceptionBacktrace;
+
+		if ( !( $e instanceof MWException ) || $e->isLoggable() ) {
+			$log = self::getLogMessage( $e );
+			if ( $wgLogExceptionBacktrace ) {
+				wfDebugLog( 'exception', $log . "\n" . $e->getTraceAsString() );
+			} else {
+				wfDebugLog( 'exception', $log );
+			}
+
+			$json = self::jsonSerializeException( $e, false, FormatJson::ALL_OK );
+			if ( $json !== false ) {
+				wfDebugLog( 'exception-json', $json, 'private' );
+			}
+		}
+
+	}
+
+}
diff --git a/includes/exception/PermissionsError.php b/includes/exception/PermissionsError.php
new file mode 100644
index 00000000..bfba7b27
--- /dev/null
+++ b/includes/exception/PermissionsError.php
@@ -0,0 +1,58 @@
+<?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;
+
+	public function __construct( $permission, $errors = array() ) {
+		global $wgLang;
+
+		$this->permission = $permission;
+
+		if ( !count( $errors ) ) {
+			$groups = array_map(
+				array( 'User', 'makeGroupLinkWiki' ),
+				User::getGroupsWithPermission( $this->permission )
+			);
+
+			if ( $groups ) {
+				$errors[] = array( 'badaccess-groups', $wgLang->commaList( $groups ), count( $groups ) );
+			} else {
+				$errors[] = array( 'badaccess-group0' );
+			}
+		}
+
+		$this->errors = $errors;
+	}
+
+	public function report() {
+		global $wgOut;
+
+		$wgOut->showPermissionsErrorPage( $this->errors, $this->permission );
+		$wgOut->output();
+	}
+}
diff --git a/includes/exception/ReadOnlyError.php b/includes/exception/ReadOnlyError.php
new file mode 100644
index 00000000..cebeb1c3
--- /dev/null
+++ b/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() ?: array()
+		);
+	}
+}
diff --git a/includes/exception/ThrottledError.php b/includes/exception/ThrottledError.php
new file mode 100644
index 00000000..bec0d904
--- /dev/null
+++ b/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/includes/exception/UserBlockedError.php b/includes/exception/UserBlockedError.php
new file mode 100644
index 00000000..9d19f8b6
--- /dev/null
+++ b/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/includes/exception/UserNotLoggedIn.php b/includes/exception/UserNotLoggedIn.php
new file mode 100644
index 00000000..03ba0b20
--- /dev/null
+++ b/includes/exception/UserNotLoggedIn.php
@@ -0,0 +1,102 @@
+<?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 LoginForm::validErrorMessages. 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 bug 37627
+ * @since 1.20
+ * @ingroup Exception
+ */
+class UserNotLoggedIn extends ErrorPageError {
+
+	/**
+	 * @note The value of the $reasonMsg parameter must be put into LoginForm::validErrorMessages
+	 * 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: array()
+	 */
+	public function __construct(
+		$reasonMsg = 'exception-nologin-text',
+		$titleMsg = 'exception-nologin',
+		$params = array()
+	) {
+		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( $this->msg, LoginForm::$validErrorMessages ) ) {
+			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( array(
+			// Return to this page when the user logs in
+			'returnto' => $context->getTitle()->getFullText(),
+			'returntoquery' => wfArrayToCgi( $query ),
+			'warning' => $this->msg,
+		) ) );
+
+		$output->output();
+	}
+}