211 lines
6.6 KiB
PHP
211 lines
6.6 KiB
PHP
<?php
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/**
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* Functions to be used with PHP's output buffer.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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*/
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namespace MediaWiki\Output;
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use MediaWiki\Logger\LoggerFactory;
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use MediaWiki\MainConfigNames;
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use MediaWiki\MediaWikiServices;
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/**
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* @since 1.31
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*/
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class OutputHandler {
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/**
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* Standard output handler for use with ob_start.
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*
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* Output buffers using this method should only be started from MW_SETUP_CALLBACK,
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* and only if there are no parent output buffers.
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*
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* @param string $s Web response output
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* @param int $phase Flags indicating the reason for the call
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* @return string
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*/
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public static function handle( $s, $phase ) {
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$config = MediaWikiServices::getInstance()->getMainConfig();
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$disableOutputCompression = $config->get( MainConfigNames::DisableOutputCompression );
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// Don't send headers if output is being discarded (T278579)
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if ( ( $phase & PHP_OUTPUT_HANDLER_CLEAN ) === PHP_OUTPUT_HANDLER_CLEAN ) {
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$logger = LoggerFactory::getInstance( 'output' );
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$logger->debug( __METHOD__ . " entrypoint={entry}; size={size}; phase=$phase", [
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'entry' => MW_ENTRY_POINT,
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'size' => strlen( $s ),
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] );
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return $s;
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}
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// Check if a compression output buffer is already enabled via php.ini. Such
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// buffers exists at the start of the request and are reflected by ob_get_level().
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$phpHandlesCompression = (
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ini_get( 'output_handler' ) === 'ob_gzhandler' ||
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ini_get( 'zlib.output_handler' ) === 'ob_gzhandler' ||
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!in_array(
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strtolower( ini_get( 'zlib.output_compression' ) ),
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[ '', 'off', '0' ]
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)
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);
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if (
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// Compression is not already handled by an internal PHP buffer
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!$phpHandlesCompression &&
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// Compression is not disabled by the application entry point
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!defined( 'MW_NO_OUTPUT_COMPRESSION' ) &&
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// Compression is not disabled by site configuration
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!$disableOutputCompression
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) {
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$s = self::handleGzip( $s );
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}
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if (
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// Response body length does not depend on internal PHP compression buffer
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!$phpHandlesCompression &&
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// Response body length does not depend on mangling by a custom buffer
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!ini_get( 'output_handler' ) &&
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!ini_get( 'zlib.output_handler' )
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) {
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self::emitContentLength( strlen( $s ) );
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}
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return $s;
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}
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/**
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* Get the "file extension" that some client apps will estimate from
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* the currently-requested URL.
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*
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* This isn't a WebRequest method, because we need it before the class loads.
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* @todo As of 2018, this actually runs after autoloader in Setup.php, so
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* WebRequest seems like a good place for this.
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*
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* @return string
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*/
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private static function findUriExtension() {
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// @todo FIXME: this sort of dupes some code in WebRequest::getRequestUrl()
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if ( isset( $_SERVER['REQUEST_URI'] ) ) {
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// Strip the query string...
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$path = explode( '?', $_SERVER['REQUEST_URI'], 2 )[0];
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} elseif ( isset( $_SERVER['SCRIPT_NAME'] ) ) {
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// Probably IIS. QUERY_STRING appears separately.
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$path = $_SERVER['SCRIPT_NAME'];
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} else {
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// Can't get the path from the server? :(
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return '';
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}
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$period = strrpos( $path, '.' );
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if ( $period !== false ) {
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return strtolower( substr( $path, $period ) );
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}
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return '';
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}
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/**
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* Handler that compresses data with gzip if allowed by the Accept header.
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*
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* Unlike ob_gzhandler, it works for HEAD requests too. This assumes that the application
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* processes them as normal GET request and that the webserver is tasked with stripping out
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* the response body before sending the response the client.
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*
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* @param string $s Web response output
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* @return string
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*/
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private static function handleGzip( $s ) {
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if ( !function_exists( 'gzencode' ) ) {
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wfDebug( __METHOD__ . "() skipping compression (gzencode unavailable)" );
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return $s;
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}
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if ( headers_sent() ) {
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wfDebug( __METHOD__ . "() skipping compression (headers already sent)" );
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return $s;
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}
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$ext = self::findUriExtension();
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if ( $ext == '.gz' || $ext == '.tgz' ) {
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// Don't do gzip compression if the URL path ends in .gz or .tgz
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// This confuses Safari and triggers a download of the page,
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// even though it's pretty clearly labeled as viewable HTML.
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// Bad Safari! Bad!
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return $s;
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}
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if ( $s === '' ) {
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// Do not gzip empty HTTP responses since that would not only bloat the body
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// length, but it would result in invalid HTTP responses when the HTTP status code
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// is one that must not be accompanied by a body (e.g. "204 No Content").
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return $s;
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}
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if ( wfClientAcceptsGzip() ) {
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wfDebug( __METHOD__ . "() is compressing output" );
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header( 'Content-Encoding: gzip' );
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$s = gzencode( $s, 6 );
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}
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// Set vary header if it hasn't been set already
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$headers = headers_list();
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$foundVary = false;
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foreach ( $headers as $header ) {
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$headerName = strtolower( substr( $header, 0, 5 ) );
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if ( $headerName == 'vary:' ) {
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$foundVary = true;
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break;
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}
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}
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if ( !$foundVary ) {
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header( 'Vary: Accept-Encoding' );
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}
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return $s;
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}
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/**
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* Set the Content-Length header if possible
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*
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* This sets Content-Length for the following cases:
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* - When the response body is meaningful (HTTP 200/404).
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* - On any HTTP 1.0 request response. This improves cooperation with certain CDNs.
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*
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* This assumes that HEAD requests are processed as GET requests by MediaWiki and that
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* the webserver is tasked with stripping out the body.
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*
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* Setting Content-Length can prevent clients from getting stuck waiting on PHP to finish
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* while deferred updates are running.
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*
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* @param int $length
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*/
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private static function emitContentLength( $length ) {
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if ( headers_sent() ) {
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wfDebug( __METHOD__ . "() headers already sent" );
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return;
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}
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if (
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in_array( http_response_code(), [ 200, 404 ], true ) ||
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( $_SERVER['SERVER_PROTOCOL'] ?? null ) === 'HTTP/1.0'
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) {
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header( "Content-Length: $length" );
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}
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}
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}
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/** @deprecated class alias since 1.41 */
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class_alias( OutputHandler::class, 'MediaWiki\\OutputHandler' );
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