Issues in DifferenceEngine.php (master) - Issues in master - wikimedia/mediawiki - Measure and Improve Code Quality continuously with Scrutinizer

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Cross-Site Scripting
Cross-Site Scripting enables an attacker to inject code into the response of a web-request that is viewed by other users. It can for example be used to bypass access controls, or even to take over other users' accounts.
File Exposure
File Exposure allows an attacker to gain access to local files that he should not be able to access. These files can for example include database credentials, or other configuration files.
File Manipulation
File Manipulation enables an attacker to write custom data to files. This potentially leads to injection of arbitrary code on the server.
Object Injection
Object Injection enables an attacker to inject an object into PHP code, and can lead to arbitrary code execution, file exposure, or file manipulation attacks.
Code Injection
Code Injection enables an attacker to execute arbitrary code on the server.
Response Splitting
Response Splitting can be used to send arbitrary responses.
File Inclusion
File Inclusion enables an attacker to inject custom files into PHP's file loading mechanism, either explicitly passed to include, or for example via PHP's auto-loading mechanism.
Command Injection
Command Injection enables an attacker to inject a shell command that is execute with the privileges of the web-server. This can be used to expose sensitive data, or gain access of your server.
SQL Injection
SQL Injection enables an attacker to execute arbitrary SQL code on your database server gaining access to user data, or manipulating user data.
XPath Injection
XPath Injection enables an attacker to modify the parts of XML document that are read. If that XML document is for example used for authentication, this can lead to further vulnerabilities similar to SQL Injection.
LDAP Injection
LDAP Injection enables an attacker to inject LDAP statements potentially granting permission to run unauthorized queries, or modify content inside the LDAP tree.
Header Injection
Other Vulnerability
This category comprises other attack vectors such as manipulating the PHP runtime, loading custom extensions, freezing the runtime, or similar.
Regex Injection
Regex Injection enables an attacker to execute arbitrary code in your PHP process.
XML Injection
XML Injection enables an attacker to read files on your local filesystem including configuration files, or can be abused to freeze your web-server process.
Variable Injection
Variable Injection enables an attacker to overwrite program variables with custom data, and can lead to further vulnerabilities.
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includes/diff/DifferenceEngine.php (13 issues)

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<?php
/**
 * User interface for the difference engine.
 *
 * 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
 * @ingroup DifferenceEngine
 */

/** @deprecated use class constant instead */
define( 'MW_DIFF_VERSION', '1.11a' );

/**
 * @todo document
 * @ingroup DifferenceEngine
 */
class DifferenceEngine extends ContextSource {
	/**
	 * Constant to indicate diff cache compatibility.
	 * Bump this when changing the diff formatting in a way that
	 * fixes important bugs or such to force cached diff views to
	 * clear.
	 */
	const DIFF_VERSION = MW_DIFF_VERSION;


	/** @var int */
	public $mOldid;

	/** @var int */
	public $mNewid;

	private $mOldTags;
	private $mNewTags;

	/** @var Content */
	public $mOldContent;

	/** @var Content */
	public $mNewContent;

	/** @var Language */
	protected $mDiffLang;

	/** @var Title */
	public $mOldPage;

	/** @var Title */
	public $mNewPage;

	/** @var Revision */
	public $mOldRev;

	/** @var Revision */
	public $mNewRev;

	/** @var bool Have the revisions IDs been loaded */
	private $mRevisionsIdsLoaded = false;

	/** @var bool Have the revisions been loaded */
	public $mRevisionsLoaded = false;

	/** @var int How many text blobs have been loaded, 0, 1 or 2? */
	public $mTextLoaded = 0;

	/** @var bool Was the diff fetched from cache? */
	public $mCacheHit = false;

	/**
	 * Set this to true to add debug info to the HTML output.
	 * Warning: this may cause RSS readers to spuriously mark articles as "new"
	 * (bug 20601)
	 */
	public $enableDebugComment = false;

	/** @var bool If true, line X is not displayed when X is 1, for example
	 *    to increase readability and conserve space with many small diffs.
	 */
	protected $mReducedLineNumbers = false;

	/** @var string Link to action=markpatrolled */
	protected $mMarkPatrolledLink = null;

	/** @var bool Show rev_deleted content if allowed */
	protected $unhide = false;

	/** @var bool Refresh the diff cache */
	protected $mRefreshCache = false;

	/**#@-*/

	/**
	 * Constructor
	 * @param IContextSource $context Context to use, anything else will be ignored
	 * @param int $old Old ID we want to show and diff with.
	 * @param string|int $new Either revision ID or 'prev' or 'next'. Default: 0.
	 * @param int $rcid Deprecated, no longer used!
	 * @param bool $refreshCache If set, refreshes the diff cache
	 * @param bool $unhide If set, allow viewing deleted revs
	 */
	public function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
		$refreshCache = false, $unhide = false
	) {
		if ( $context instanceof IContextSource ) {
			$this->setContext( $context );
		}

		wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );

		$this->mOldid = $old;
		$this->mNewid = $new;
		$this->mRefreshCache = $refreshCache;
		$this->unhide = $unhide;
	}

	/**
	 * @param bool $value
	 */
	public function setReducedLineNumbers( $value = true ) {
		$this->mReducedLineNumbers = $value;
	}

	/**
	 * @return Language
	 */
	public function getDiffLang() {
		if ( $this->mDiffLang === null ) {
			# Default language in which the diff text is written.
			$this->mDiffLang = $this->getTitle()->getPageLanguage();
		}

		return $this->mDiffLang;
	}

	/**
	 * @return bool
	 */
	public function wasCacheHit() {
		return $this->mCacheHit;
	}

	/**
	 * @return int
	 */
	public function getOldid() {
		$this->loadRevisionIds();

		return $this->mOldid;
	}

	/**
	 * @return bool|int
	 */
	public function getNewid() {
		$this->loadRevisionIds();

		return $this->mNewid;
	}

	/**
	 * Look up a special:Undelete link to the given deleted revision id,
	 * as a workaround for being unable to load deleted diffs in currently.
	 *
	 * @param int $id Revision ID
	 *
	 * @return string|bool Link HTML or false
	 */
	public function deletedLink( $id ) {
		if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
			$dbr = wfGetDB( DB_REPLICA );
			$row = $dbr->selectRow( 'archive', '*',
				[ 'ar_rev_id' => $id ],
				__METHOD__ );
			if ( $row ) {
				$rev = Revision::newFromArchiveRow( $row );
				$title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );

				return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( [
					'target' => $title->getPrefixedText(),
					'timestamp' => $rev->getTimestamp()
				] );
			}
		}

		return false;
	}

	/**
	 * Build a wikitext link toward a deleted revision, if viewable.
	 *
	 * @param int $id Revision ID
	 *
	 * @return string Wikitext fragment
	 */
	public function deletedIdMarker( $id ) {
		$link = $this->deletedLink( $id );
		if ( $link ) {
''   == false // true
''   == null  // true
'ab' == false // false
'ab' == null  // false

// It is often better to use strict comparison
'' === false // false
'' === null  // false
			return "[$link $id]";
		} else {
			return $id;
		}
	}

	private function showMissingRevision() {
		$out = $this->getOutput();

		$missing = [];
		if ( $this->mOldRev === null ||
			( $this->mOldRev && $this->mOldContent === null )
		) {
			$missing[] = $this->deletedIdMarker( $this->mOldid );
		}
		if ( $this->mNewRev === null ||
			( $this->mNewRev && $this->mNewContent === null )
		) {
			$missing[] = $this->deletedIdMarker( $this->mNewid );
		}

		$out->setPageTitle( $this->msg( 'errorpagetitle' ) );
		$msg = $this->msg( 'difference-missing-revision' )
			->params( $this->getLanguage()->listToText( $missing ) )
			->numParams( count( $missing ) )
			->parseAsBlock();
		$out->addHTML( $msg );
	}

	public function showDiffPage( $diffOnly = false ) {
		# Allow frames except in certain special cases
		$out = $this->getOutput();
		$out->allowClickjacking();
		$out->setRobotPolicy( 'noindex,nofollow' );

		// Allow extensions to add any extra output here
		Hooks::run( 'DifferenceEngineShowDiffPage', [ $out ] );

		if ( !$this->loadRevisionData() ) {
			$this->showMissingRevision();

			return;
		}

		$user = $this->getUser();
		$permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
		if ( $this->mOldPage ) { # mOldPage might not be set, see below.
			$permErrors = wfMergeErrorArrays( $permErrors,
				$this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
		}
		if ( count( $permErrors ) ) {
			throw new PermissionsError( 'read', $permErrors );
		}

		$rollback = '';

		$query = [];
		# Carry over 'diffonly' param via navigation links
		if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
			$query['diffonly'] = $diffOnly;
		}
		# Cascade unhide param in links for easy deletion browsing
		if ( $this->unhide ) {
			$query['unhide'] = 1;
		}

		# Check if one of the revisions is deleted/suppressed
		$deleted = $suppressed = false;
		$allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );

		$revisionTools = [];

		# mOldRev is false if the difference engine is called with a "vague" query for
		# a diff between a version V and its previous version V' AND the version V
		# is the first version of that article. In that case, V' does not exist.
		if ( $this->mOldRev === false ) {
			$out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
			$samePage = true;
			$oldHeader = '';
			// Allow extensions to change the $oldHeader variable
			Hooks::run( 'DifferenceEngineOldHeaderNoOldRev', [ &$oldHeader ] );
		} else {
			Hooks::run( 'DiffViewHeader', [ $this, $this->mOldRev, $this->mNewRev ] );

			if ( $this->mNewPage->equals( $this->mOldPage ) ) {
				$out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
				$samePage = true;
			} else {
				$out->setPageTitle( $this->msg( 'difference-title-multipage',
					$this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
				$out->addSubtitle( $this->msg( 'difference-multipage' ) );
				$samePage = false;
			}

			if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
				if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
					$rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
					if ( $rollbackLink ) {
						$out->preventClickjacking();
						$rollback = '&#160;&#160;&#160;' . $rollbackLink;
					}
				}

				if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) &&
					!$this->mNewRev->isDeleted( Revision::DELETED_TEXT )
				) {
					$undoLink = Html::element( 'a', [
							'href' => $this->mNewPage->getLocalURL( [
								'action' => 'edit',
								'undoafter' => $this->mOldid,
								'undo' => $this->mNewid
							] ),
							'title' => Linker::titleAttrib( 'undo' ),
						],
						$this->msg( 'editundo' )->text()
					);
					$revisionTools['mw-diff-undo'] = $undoLink;
				}
			}

			# Make "previous revision link"
			if ( $samePage && $this->mOldRev->getPrevious() ) {
				$prevlink = Linker::linkKnown(
					$this->mOldPage,
					$this->msg( 'previousdiff' )->escaped(),
					[ 'id' => 'differences-prevlink' ],
					[ 'diff' => 'prev', 'oldid' => $this->mOldid ] + $query
				);
			} else {
				$prevlink = '&#160;';
			}

			if ( $this->mOldRev->isMinor() ) {
				$oldminor = ChangesList::flag( 'minor' );
			} else {
				$oldminor = '';
			}

			$ldel = $this->revisionDeleteLink( $this->mOldRev );
			$oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
			$oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff', $this->getContext() );

			$oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
				'<div id="mw-diff-otitle2">' .
				Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
				'<div id="mw-diff-otitle3">' . $oldminor .
				Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
				'<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
				'<div id="mw-diff-otitle4">' . $prevlink . '</div>';

			// Allow extensions to change the $oldHeader variable
			Hooks::run( 'DifferenceEngineOldHeader', [ $this, &$oldHeader, $prevlink, $oldminor,
				$diffOnly, $ldel, $this->unhide ] );

			if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
				$deleted = true; // old revisions text is hidden
				if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
					$suppressed = true; // also suppressed
				}
			}

			# Check if this user can see the revisions
			if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
				$allowed = false;
			}
		}

		# Make "next revision link"
		# Skip next link on the top revision
		if ( $samePage && !$this->mNewRev->isCurrent() ) {
			$nextlink = Linker::linkKnown(
				$this->mNewPage,
				$this->msg( 'nextdiff' )->escaped(),
				[ 'id' => 'differences-nextlink' ],
				[ 'diff' => 'next', 'oldid' => $this->mNewid ] + $query
			);
		} else {
			$nextlink = '&#160;';
		}

		if ( $this->mNewRev->isMinor() ) {
			$newminor = ChangesList::flag( 'minor' );
		} else {
			$newminor = '';
		}

		# Handle RevisionDelete links...
		$rdel = $this->revisionDeleteLink( $this->mNewRev );

		# Allow extensions to define their own revision tools
		Hooks::run( 'DiffRevisionTools',
			[ $this->mNewRev, &$revisionTools, $this->mOldRev, $user ] );
		$formattedRevisionTools = [];
		// Put each one in parentheses (poor man's button)
		foreach ( $revisionTools as $key => $tool ) {
			$toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
			$element = Html::rawElement(
				'span',
				[ 'class' => $toolClass ],
				$this->msg( 'parentheses' )->rawParams( $tool )->escaped()
			);
			$formattedRevisionTools[] = $element;
		}
		$newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
			' ' . implode( ' ', $formattedRevisionTools );
		$newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff', $this->getContext() );

		$newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
			'<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
			" $rollback</div>" .
			'<div id="mw-diff-ntitle3">' . $newminor .
			Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
			'<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
			'<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';

		// Allow extensions to change the $newHeader variable
		Hooks::run( 'DifferenceEngineNewHeader', [ $this, &$newHeader, $formattedRevisionTools,
			$nextlink, $rollback, $newminor, $diffOnly, $rdel, $this->unhide ] );

		if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
			$deleted = true; // new revisions text is hidden
			if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
				$suppressed = true; // also suppressed
			}
		}

		# If the diff cannot be shown due to a deleted revision, then output
		# the diff header and links to unhide (if available)...
		if ( $deleted && ( !$this->unhide || !$allowed ) ) {
			$this->showDiffStyle();
			$multi = $this->getMultiNotice();
			$out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
			if ( !$allowed ) {
				$msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
				# Give explanation for why revision is not visible
				$out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
					[ $msg ] );
			} else {
				# Give explanation and add a link to view the diff...
				$query = $this->getRequest()->appendQueryValue( 'unhide', '1' );
				$link = $this->getTitle()->getFullURL( $query );
				$msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
				$out->wrapWikiMsg(
					"<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
					[ $msg, $link ]
				);
			}
		# Otherwise, output a regular diff...
		} else {
			# Add deletion notice if the user is viewing deleted content
			$notice = '';
			if ( $deleted ) {
				$msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
				$notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
					$this->msg( $msg )->parse() .
					"</div>\n";
			}
			$this->showDiff( $oldHeader, $newHeader, $notice );
			if ( !$diffOnly ) {
				$this->renderNewRevision();
			}
		}
	}

	/**
	 * Build a link to mark a change as patrolled.
	 *
	 * Returns empty string if there's either no revision to patrol or the user is not allowed to.
	 * Side effect: When the patrol link is build, this method will call
	 * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
	 *
	 * @return string HTML or empty string
	 */
	protected function markPatrolledLink() {
		if ( $this->mMarkPatrolledLink === null ) {
			$linkInfo = $this->getMarkPatrolledLinkInfo();
			// If false, there is no patrol link needed/allowed
			if ( !$linkInfo ) {
				$this->mMarkPatrolledLink = '';
			} else {
				$this->mMarkPatrolledLink = ' <span class="patrollink" data-mw="interface">[' .
					Linker::linkKnown(
						$this->mNewPage,
						$this->msg( 'markaspatrolleddiff' )->escaped(),
						[],
						[
							'action' => 'markpatrolled',
							'rcid' => $linkInfo['rcid'],
						]
					) . ']</span>';
				// Allow extensions to change the markpatrolled link
				Hooks::run( 'DifferenceEngineMarkPatrolledLink', [ $this,
					&$this->mMarkPatrolledLink, $linkInfo['rcid'] ] );
			}
		}
		return $this->mMarkPatrolledLink;
	}

	/**
	 * Returns an array of meta data needed to build a "mark as patrolled" link and
	 * adds the mediawiki.page.patrol.ajax to the output.
	 *
	 * @return array|false An array of meta data for a patrol link (rcid only)
	 *  or false if no link is needed
	 */
	protected function getMarkPatrolledLinkInfo() {
		global $wgUseRCPatrol, $wgEnableAPI, $wgEnableWriteAPI;

		$user = $this->getUser();

		// Prepare a change patrol link, if applicable
		if (
			// Is patrolling enabled and the user allowed to?
			$wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
			// Only do this if the revision isn't more than 6 hours older
			// than the Max RC age (6h because the RC might not be cleaned out regularly)
			RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
		) {
			// Look for an unpatrolled change corresponding to this diff
			$db = wfGetDB( DB_REPLICA );
			$change = RecentChange::newFromConds(
				[
					'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
					'rc_this_oldid' => $this->mNewid,
					'rc_patrolled' => 0
				],
				__METHOD__
			);

			if ( $change && !$change->getPerformer()->equals( $user ) ) {
				$rcid = $change->getAttribute( 'rc_id' );
			} else {
				// None found or the page has been created by the current user.
				// If the user could patrol this it already would be patrolled
				$rcid = 0;
			}

			// Allow extensions to possibly change the rcid here
			// For example the rcid might be set to zero due to the user
			// being the same as the performer of the change but an extension
			// might still want to show it under certain conditions
			Hooks::run( 'DifferenceEngineMarkPatrolledRCID', [ &$rcid, $this, $change, $user ] );

			// Build the link
			if ( $rcid ) {
				$this->getOutput()->preventClickjacking();
				if ( $wgEnableAPI && $wgEnableWriteAPI
					&& $user->isAllowed( 'writeapi' )
				) {
					$this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
				}

				return [
					'rcid' => $rcid,
				];
			}
		}

		// No mark as patrolled link applicable
		return false;
	}

	/**
	 * @param Revision $rev
	 *
	 * @return string
	 */
	protected function revisionDeleteLink( $rev ) {
		$link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
/** @return stdClass|null */
function mayReturnNull() { }

function doesNotAcceptNull(stdClass $x) { }

// With potential error.
function withoutCheck() {
    $x = mayReturnNull();
    doesNotAcceptNull($x); // Potential error here.
}

// Safe - Alternative 1
function withCheck1() {
    $x = mayReturnNull();
    if ( ! $x instanceof stdClass) {
        throw new \LogicException('$x must be defined.');
    }
    doesNotAcceptNull($x);
}

// Safe - Alternative 2
function withCheck2() {
    $x = mayReturnNull();
    if ($x instanceof stdClass) {
        doesNotAcceptNull($x);
    }
}
		if ( $link !== '' ) {
			$link = '&#160;&#160;&#160;' . $link . ' ';
		}

		return $link;
	}

	/**
	 * Show the new revision of the page.
	 */
	public function renderNewRevision() {
		$out = $this->getOutput();
		$revHeader = $this->getRevisionHeader( $this->mNewRev );
		# Add "current version as of X" title
		$out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
		<h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
		# Page content may be handled by a hooked call instead...
		# @codingStandardsIgnoreStart Ignoring long lines.
		if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
			$this->loadNewText();
			$out->setRevisionId( $this->mNewid );
			$out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );

			$out->setArticleFlag( true );

			// NOTE: only needed for B/C: custom rendering of JS/CSS via hook
			if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
				// This needs to be synchronised with Article::showCssOrJsPage(), which sucks
				// Give hooks a chance to customise the output
				// @todo standardize this crap into one function
				if ( ContentHandler::runLegacyHooks( 'ShowRawCssJs', [ $this->mNewContent, $this->mNewPage, $out ], '1.24' ) ) {
					// NOTE: deprecated hook, B/C only
					// use the content object's own rendering
					$cnt = $this->mNewRev->getContent();
					$po = $cnt ? $cnt->getParserOutput( $this->mNewRev->getTitle(), $this->mNewRev->getId() ) : null;
/** @return stdClass|null */
function mayReturnNull() { }

function doesNotAcceptNull(stdClass $x) { }

// With potential error.
function withoutCheck() {
    $x = mayReturnNull();
    doesNotAcceptNull($x); // Potential error here.
}

// Safe - Alternative 1
function withCheck1() {
    $x = mayReturnNull();
    if ( ! $x instanceof stdClass) {
        throw new \LogicException('$x must be defined.');
    }
    doesNotAcceptNull($x);
}

// Safe - Alternative 2
function withCheck2() {
    $x = mayReturnNull();
    if ($x instanceof stdClass) {
        doesNotAcceptNull($x);
    }
}
					if ( $po ) {
						$out->addParserOutputContent( $po );
					}
				}
			} elseif ( !Hooks::run( 'ArticleContentViewCustom', [ $this->mNewContent, $this->mNewPage, $out ] ) ) {
				// Handled by extension
			} elseif ( !ContentHandler::runLegacyHooks(
				'ArticleViewCustom',
				[ $this->mNewContent, $this->mNewPage, $out ],
				'1.21'
			) ) {
				// NOTE: deprecated hook, B/C only
				// Handled by extension
			} else {
				// Normal page
				if ( $this->getTitle()->equals( $this->mNewPage ) ) {
					// If the Title stored in the context is the same as the one
					// of the new revision, we can use its associated WikiPage
					// object.
					$wikiPage = $this->getWikiPage();
				} else {
					// Otherwise we need to create our own WikiPage object
					$wikiPage = WikiPage::factory( $this->mNewPage );
				}

				$parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
/** @return stdClass|null */
function mayReturnNull() { }

function doesNotAcceptNull(stdClass $x) { }

// With potential error.
function withoutCheck() {
    $x = mayReturnNull();
    doesNotAcceptNull($x); // Potential error here.
}

// Safe - Alternative 1
function withCheck1() {
    $x = mayReturnNull();
    if ( ! $x instanceof stdClass) {
        throw new \LogicException('$x must be defined.');
    }
    doesNotAcceptNull($x);
}

// Safe - Alternative 2
function withCheck2() {
    $x = mayReturnNull();
    if ($x instanceof stdClass) {
        doesNotAcceptNull($x);
    }
}

				# WikiPage::getParserOutput() should not return false, but just in case
				if ( $parserOutput ) {
					// Allow extensions to change parser output here
					if ( Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput', [ $this, $out, $parserOutput, $wikiPage ] ) ) {
						$out->addParserOutput( $parserOutput );
/**
 * @return array|string
 */
function returnsDifferentValues($x) {
    if ($x) {
        return 'foo';
    }

    return array();
}

$x = returnsDifferentValues($y);
if (is_array($x)) {
    // $x is an array.
}
					}
				}
			}
		}
		# @codingStandardsIgnoreEnd

		// Allow extensions to optionally not show the final patrolled link
		if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
			# Add redundant patrol link on bottom...
			$out->addHTML( $this->markPatrolledLink() );
		}
	}

	protected function getParserOutput( WikiPage $page, Revision $rev ) {
		$parserOptions = $page->makeParserOptions( $this->getContext() );

		if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( 'edit', $this->getUser() ) ) {
			$parserOptions->setEditSection( false );
		}

		$parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );

		return $parserOutput;
	}

	/**
	 * Get the diff text, send it to the OutputPage object
	 * Returns false if the diff could not be generated, otherwise returns true
	 *
	 * @param string|bool $otitle Header for old text or false
	 * @param string|bool $ntitle Header for new text or false
	 * @param string $notice HTML between diff header and body
	 *
	 * @return bool
	 */
	public function showDiff( $otitle, $ntitle, $notice = '' ) {
		// Allow extensions to affect the output here
		Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );

		$diff = $this->getDiff( $otitle, $ntitle, $notice );
		if ( $diff === false ) {
			$this->showMissingRevision();

			return false;
		} else {
			$this->showDiffStyle();
			$this->getOutput()->addHTML( $diff );

			return true;
		}
	}

	/**
	 * Add style sheets for diff display.
	 */
	public function showDiffStyle() {
		$this->getOutput()->addModuleStyles( 'mediawiki.diff.styles' );
	}

	/**
	 * Get complete diff table, including header
	 *
	 * @param string|bool $otitle Header for old text or false
	 * @param string|bool $ntitle Header for new text or false
	 * @param string $notice HTML between diff header and body
	 *
	 * @return mixed
	 */
	public function getDiff( $otitle, $ntitle, $notice = '' ) {
		$body = $this->getDiffBody();
		if ( $body === false ) {
			return false;
		}

		$multi = $this->getMultiNotice();
		// Display a message when the diff is empty
		if ( $body === '' ) {
			$notice .= '<div class="mw-diff-empty">' .
				$this->msg( 'diff-empty' )->parse() .
				"</div>\n";
		}

		return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );

	}

	/**
	 * Get the diff table body, without header
	 *
	 * @return mixed (string/false)
	 */
	public function getDiffBody() {
		$this->mCacheHit = true;
		// Check if the diff should be hidden from this user
		if ( !$this->loadRevisionData() ) {
			return false;
		} elseif ( $this->mOldRev &&
			!$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
		) {
			return false;
		} elseif ( $this->mNewRev &&
			!$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
		) {
			return false;
		}
		// Short-circuit
		if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
			&& $this->mOldRev->getId() == $this->mNewRev->getId() )
		) {
			if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
				return '';
			}
		}
		// Cacheable?
		$key = false;
		$cache = ObjectCache::getMainWANInstance();
		if ( $this->mOldid && $this->mNewid ) {
			$key = $this->getDiffBodyCacheKey();

			// Try cache
			if ( !$this->mRefreshCache ) {
				$difftext = $cache->get( $key );
				if ( $difftext ) {
					wfIncrStats( 'diff_cache.hit' );
					$difftext = $this->localiseLineNumbers( $difftext );
					$difftext .= "\n<!-- diff cache key $key -->\n";

					return $difftext;
				}
			} // don't try to load but save the result
		}
		$this->mCacheHit = false;

		// Loadtext is permission safe, this just clears out the diff
		if ( !$this->loadText() ) {
			return false;
		}

		$difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );

		// Save to cache for 7 days
		if ( !Hooks::run( 'AbortDiffCache', [ &$this ] ) ) {
			wfIncrStats( 'diff_cache.uncacheable' );
		} elseif ( $key !== false && $difftext !== false ) {
			wfIncrStats( 'diff_cache.miss' );
			$cache->set( $key, $difftext, 7 * 86400 );
		} else {
			wfIncrStats( 'diff_cache.uncacheable' );
		}
		// Replace line numbers with the text in the user's language
		if ( $difftext !== false ) {
			$difftext = $this->localiseLineNumbers( $difftext );
/**
 * @return array|string
 */
function returnsDifferentValues($x) {
    if ($x) {
        return 'foo';
    }

    return array();
}

$x = returnsDifferentValues($y);
if (is_array($x)) {
    // $x is an array.
}
		}

		return $difftext;
	}

	/**
	 * Returns the cache key for diff body text or content.
	 *
	 * @since 1.23
	 *
	 * @throws MWException
	 * @return string
	 */
	protected function getDiffBodyCacheKey() {
		if ( !$this->mOldid || !$this->mNewid ) {
			throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
		}

		return wfMemcKey( 'diff', 'version', self::DIFF_VERSION,
			'oldid', $this->mOldid, 'newid', $this->mNewid );
	}

	/**
	 * Generate a diff, no caching.
	 *
	 * This implementation uses generateTextDiffBody() to generate a diff based on the default
	 * serialization of the given Content objects. This will fail if $old or $new are not
	 * instances of TextContent.
	 *
	 * Subclasses may override this to provide a different rendering for the diff,
	 * perhaps taking advantage of the content's native form. This is required for all content
	 * models that are not text based.
	 *
	 * @since 1.21
	 *
	 * @param Content $old Old content
	 * @param Content $new New content
	 *
	 * @throws MWException If old or new content is not an instance of TextContent.
	 * @return bool|string
	 */
	public function generateContentDiffBody( Content $old, Content $new ) {
		if ( !( $old instanceof TextContent ) ) {
			throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
				"override generateContentDiffBody to fix this." );
		}

		if ( !( $new instanceof TextContent ) ) {
			throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
				. "override generateContentDiffBody to fix this." );
		}

		$otext = $old->serialize();
		$ntext = $new->serialize();

		return $this->generateTextDiffBody( $otext, $ntext );
	}

	/**
	 * Generate a diff, no caching
	 *
	 * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
	 *
	 * @param string $otext Old text, must be already segmented
	 * @param string $ntext New text, must be already segmented
	 *
	 * @return bool|string
	 */
	public function generateTextDiffBody( $otext, $ntext ) {
		$diff = function() use ( $otext, $ntext ) {
			$time = microtime( true );

			$result = $this->textDiff( $otext, $ntext );

			$time = intval( ( microtime( true ) - $time ) * 1000 );
			$this->getStats()->timing( 'diff_time', $time );
			// Log requests slower than 99th percentile
			if ( $time > 100 && $this->mOldPage && $this->mNewPage ) {
				wfDebugLog( 'diff',
					"$time ms diff: {$this->mOldid} -> {$this->mNewid} {$this->mNewPage}" );
			}

			return $result;
		};

		/**
		 * @param Status $status
		 * @throws FatalError
		 */
		$error = function( $status ) {
			throw new FatalError( $status->getWikiText() );
		};

		// Use PoolCounter if the diff looks like it can be expensive
		if ( strlen( $otext ) + strlen( $ntext ) > 20000 ) {
			$work = new PoolCounterWorkViaCallback( 'diff',
				md5( $otext ) . md5( $ntext ),
				[ 'doWork' => $diff, 'error' => $error ]
			);
			return $work->execute();
		}

		return $diff();
	}

	/**
	 * Generates diff, to be wrapped internally in a logging/instrumentation
	 *
	 * @param string $otext Old text, must be already segmented
	 * @param string $ntext New text, must be already segmented
	 * @return bool|string
	 */
	protected function textDiff( $otext, $ntext ) {
		global $wgExternalDiffEngine, $wgContLang;

		$otext = str_replace( "\r\n", "\n", $otext );
		$ntext = str_replace( "\r\n", "\n", $ntext );

		if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
			wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
			$wgExternalDiffEngine = false;
		} elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
			// Same as above, but with no deprecation warnings
			$wgExternalDiffEngine = false;
		} elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
			// And prevent people from shooting themselves in the foot...
			wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
			$wgExternalDiffEngine = false;
		}

		if ( function_exists( 'wikidiff2_do_diff' ) && $wgExternalDiffEngine === false ) {
			# Better external diff engine, the 2 may some day be dropped
			# This one does the escaping and segmenting itself
			$text = wikidiff2_do_diff( $otext, $ntext, 2 );
			$text .= $this->debug( 'wikidiff2' );

			return $text;
		} elseif ( $wgExternalDiffEngine !== false && is_executable( $wgExternalDiffEngine ) ) {
			# Diff via the shell
			$tmpDir = wfTempDir();
			$tempName1 = tempnam( $tmpDir, 'diff_' );
			$tempName2 = tempnam( $tmpDir, 'diff_' );

			$tempFile1 = fopen( $tempName1, "w" );
			if ( !$tempFile1 ) {
				return false;
			}
			$tempFile2 = fopen( $tempName2, "w" );
			if ( !$tempFile2 ) {
				return false;
			}
			fwrite( $tempFile1, $otext );
			fwrite( $tempFile2, $ntext );
			fclose( $tempFile1 );
			fclose( $tempFile2 );
			$cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
			$difftext = wfShellExec( $cmd );
			$difftext .= $this->debug( "external $wgExternalDiffEngine" );
			unlink( $tempName1 );
			unlink( $tempName2 );

			return $difftext;
		}

		# Native PHP diff
		$ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
		$nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
		$diffs = new Diff( $ota, $nta );
		$formatter = new TableDiffFormatter();
		$difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );

		return $difftext;
	}

	/**
	 * Generate a debug comment indicating diff generating time,
	 * server node, and generator backend.
	 *
	 * @param string $generator : What diff engine was used
	 *
	 * @return string
	 */
	protected function debug( $generator = "internal" ) {
		global $wgShowHostnames;
		if ( !$this->enableDebugComment ) {
			return '';
		}
		$data = [ $generator ];
		if ( $wgShowHostnames ) {
			$data[] = wfHostname();
		}
		$data[] = wfTimestamp( TS_DB );

		return "<!-- diff generator: " .
			implode( " ", array_map( "htmlspecialchars", $data ) ) .
			" -->\n";
	}

	/**
	 * Replace line numbers with the text in the user's language
	 *
	 * @param string $text
	 *
	 * @return mixed
	 */
	public function localiseLineNumbers( $text ) {
		return preg_replace_callback(
			'/<!--LINE (\d+)-->/',
			[ &$this, 'localiseLineNumbersCb' ],
			$text
		);
	}

	public function localiseLineNumbersCb( $matches ) {
		if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
			return '';
		}

		return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
	}

	/**
	 * If there are revisions between the ones being compared, return a note saying so.
	 *
	 * @return string
	 */
	public function getMultiNotice() {
		if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
			return '';
		} elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
			// Comparing two different pages? Count would be meaningless.
			return '';
		}

		if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
			$oldRev = $this->mNewRev; // flip
			$newRev = $this->mOldRev; // flip
		} else { // normal case
			$oldRev = $this->mOldRev;
			$newRev = $this->mNewRev;
		}

		// Sanity: don't show the notice if too many rows must be scanned
		// @todo show some special message for that case
		$nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
		if ( $nEdits > 0 && $nEdits <= 1000 ) {
			$limit = 100; // use diff-multi-manyusers if too many users
			$users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
			$numUsers = count( $users );

			if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
				$numUsers = 0; // special case to say "by the same user" instead of "by one other user"
			}

			return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
		}

		return ''; // nothing
	}

	/**
	 * Get a notice about how many intermediate edits and users there are
	 *
	 * @param int $numEdits
	 * @param int $numUsers
	 * @param int $limit
	 *
	 * @return string
	 */
	public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
		if ( $numUsers === 0 ) {
			$msg = 'diff-multi-sameuser';
		} elseif ( $numUsers > $limit ) {
			$msg = 'diff-multi-manyusers';
			$numUsers = $limit;
		} else {
			$msg = 'diff-multi-otherusers';
		}

		return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
	}

	/**
	 * Get a header for a specified revision.
	 *
	 * @param Revision $rev
	 * @param string $complete 'complete' to get the header wrapped depending
	 *        the visibility of the revision and a link to edit the page.
	 *
	 * @return string HTML fragment
	 */
	protected function getRevisionHeader( Revision $rev, $complete = '' ) {
		$lang = $this->getLanguage();
		$user = $this->getUser();
		$revtimestamp = $rev->getTimestamp();
		$timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
		$dateofrev = $lang->userDate( $revtimestamp, $user );
		$timeofrev = $lang->userTime( $revtimestamp, $user );

		$header = $this->msg(
			$rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
			$timestamp,
			$dateofrev,
			$timeofrev
		)->escaped();

		if ( $complete !== 'complete' ) {
			return $header;
		}

		$title = $rev->getTitle();

		$header = Linker::linkKnown( $title, $header, [],
			[ 'oldid' => $rev->getId() ] );

		if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
			$editQuery = [ 'action' => 'edit' ];
			if ( !$rev->isCurrent() ) {
				$editQuery['oldid'] = $rev->getId();
			}

			$key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
			$msg = $this->msg( $key )->escaped();
			$editLink = $this->msg( 'parentheses' )->rawParams(
				Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
			$header .= ' ' . Html::rawElement(
				'span',
				[ 'class' => 'mw-diff-edit' ],
				$editLink
			);
			if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
				$header = Html::rawElement(
					'span',
					[ 'class' => 'history-deleted' ],
					$header
				);
			}
		} else {
			$header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
		}

		return $header;
	}

	/**
	 * Add the header to a diff body
	 *
	 * @param string $diff Diff body
	 * @param string $otitle Old revision header
	 * @param string $ntitle New revision header
	 * @param string $multi Notice telling user that there are intermediate
	 *   revisions between the ones being compared
	 * @param string $notice Other notices, e.g. that user is viewing deleted content
	 *
	 * @return string
	 */
	public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
		// shared.css sets diff in interface language/dir, but the actual content
		// is often in a different language, mostly the page content language/dir
		$header = Html::openElement( 'table', [
			'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
			'data-mw' => 'interface',
		] );
		$userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );

		if ( !$diff && !$otitle ) {
			$header .= "
			<tr style='vertical-align: top;' lang='{$userLang}'>
			<td class='diff-ntitle'>{$ntitle}</td>
			</tr>";
			$multiColspan = 1;
		} else {
			if ( $diff ) { // Safari/Chrome show broken output if cols not used
				$header .= "
				<col class='diff-marker' />
				<col class='diff-content' />
				<col class='diff-marker' />
				<col class='diff-content' />";
				$colspan = 2;
				$multiColspan = 4;
			} else {
				$colspan = 1;
				$multiColspan = 2;
			}
			if ( $otitle || $ntitle ) {
				$header .= "
				<tr style='vertical-align: top;' lang='{$userLang}'>
				<td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
				<td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
				</tr>";
			}
		}

		if ( $multi != '' ) {
			$header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' " .
				"class='diff-multi' lang='{$userLang}'>{$multi}</td></tr>";
		}
		if ( $notice != '' ) {
			$header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' " .
				"lang='{$userLang}'>{$notice}</td></tr>";
		}

		return $header . $diff . "</table>";
	}

	/**
	 * Use specified text instead of loading from the database
	 * @param Content $oldContent
	 * @param Content $newContent
	 * @since 1.21
	 */
	public function setContent( Content $oldContent, Content $newContent ) {
		$this->mOldContent = $oldContent;
		$this->mNewContent = $newContent;

		$this->mTextLoaded = 2;
		$this->mRevisionsLoaded = true;
	}

	/**
	 * Set the language in which the diff text is written
	 * (Defaults to page content language).
	 * @param Language|string $lang
	 * @since 1.19
	 */
	public function setTextLanguage( $lang ) {
		$this->mDiffLang = wfGetLangObj( $lang );
	}

	/**
	 * Maps a revision pair definition as accepted by DifferenceEngine constructor
	 * to a pair of actual integers representing revision ids.
	 *
	 * @param int $old Revision id, e.g. from URL parameter 'oldid'
	 * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
	 *
	 * @return int[] List of two revision ids, older first, later second.
	 *     Zero signifies invalid argument passed.
	 *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
	 */
	public function mapDiffPrevNext( $old, $new ) {
		if ( $new === 'prev' ) {
			// Show diff between revision $old and the previous one. Get previous one from DB.
			$newid = intval( $old );
			$oldid = $this->getTitle()->getPreviousRevisionID( $newid );
		} elseif ( $new === 'next' ) {
			// Show diff between revision $old and the next one. Get next one from DB.
			$oldid = intval( $old );
			$newid = $this->getTitle()->getNextRevisionID( $oldid );
		} else {
			$oldid = intval( $old );
			$newid = intval( $new );
		}

		return [ $oldid, $newid ];
	}

	/**
	 * Load revision IDs
	 */
	private function loadRevisionIds() {
		if ( $this->mRevisionsIdsLoaded ) {
			return;
		}

		$this->mRevisionsIdsLoaded = true;

		$old = $this->mOldid;
		$new = $this->mNewid;

		list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
		if ( $new === 'next' && $this->mNewid === false ) {
			# if no result, NewId points to the newest old revision. The only newer
			# revision is cur, which is "0".
			$this->mNewid = 0;
		}

		Hooks::run(
			'NewDifferenceEngine',
			[ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
		);
	}

	/**
	 * Load revision metadata for the specified articles. If newid is 0, then compare
	 * the old article in oldid to the current article; if oldid is 0, then
	 * compare the current article to the immediately previous one (ignoring the
	 * value of newid).
	 *
	 * If oldid is false, leave the corresponding revision object set
	 * to false. This is impossible via ordinary user input, and is provided for
	 * API convenience.
	 *
	 * @return bool
	 */
	public function loadRevisionData() {
		if ( $this->mRevisionsLoaded ) {
			return true;
		}

		// Whether it succeeds or fails, we don't want to try again
		$this->mRevisionsLoaded = true;

		$this->loadRevisionIds();

		// Load the new revision object
		if ( $this->mNewid ) {
			$this->mNewRev = Revision::newFromId( $this->mNewid );
		} else {
			$this->mNewRev = Revision::newFromTitle(
				$this->getTitle(),
/** @return stdClass|null */
function mayReturnNull() { }

function doesNotAcceptNull(stdClass $x) { }

// With potential error.
function withoutCheck() {
    $x = mayReturnNull();
    doesNotAcceptNull($x); // Potential error here.
}

// Safe - Alternative 1
function withCheck1() {
    $x = mayReturnNull();
    if ( ! $x instanceof stdClass) {
        throw new \LogicException('$x must be defined.');
    }
    doesNotAcceptNull($x);
}

// Safe - Alternative 2
function withCheck2() {
    $x = mayReturnNull();
    if ($x instanceof stdClass) {
        doesNotAcceptNull($x);
    }
}
				false,
				Revision::READ_NORMAL
			);
		}

		if ( !$this->mNewRev instanceof Revision ) {
			return false;
		}

		// Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
		$this->mNewid = $this->mNewRev->getId();
		$this->mNewPage = $this->mNewRev->getTitle();

		// Load the old revision object
		$this->mOldRev = false;

		if ( $this->mOldid ) {
			$this->mOldRev = Revision::newFromId( $this->mOldid );
		} elseif ( $this->mOldid === 0 ) {
			$rev = $this->mNewRev->getPrevious();
			if ( $rev ) {
				$this->mOldid = $rev->getId();
				$this->mOldRev = $rev;
			} else {
				// No previous revision; mark to show as first-version only.
				$this->mOldid = false;
$answer = 42;

$correct = false;

$correct = (bool) $answer;
				$this->mOldRev = false;
			}
		} /* elseif ( $this->mOldid === false ) leave mOldRev false; */

		if ( is_null( $this->mOldRev ) ) {
			return false;
		}

		if ( $this->mOldRev ) {
			$this->mOldPage = $this->mOldRev->getTitle();
		}

		// Load tags information for both revisions
		$dbr = wfGetDB( DB_REPLICA );
		if ( $this->mOldid !== false ) {
			$this->mOldTags = $dbr->selectField(
				'tag_summary',
				'ts_tags',
				[ 'ts_rev_id' => $this->mOldid ],
				__METHOD__
			);
		} else {
			$this->mOldTags = false;
		}
		$this->mNewTags = $dbr->selectField(
			'tag_summary',
			'ts_tags',
			[ 'ts_rev_id' => $this->mNewid ],
			__METHOD__
		);

		return true;
	}

	/**
	 * Load the text of the revisions, as well as revision data.
	 *
	 * @return bool
	 */
	public function loadText() {
		if ( $this->mTextLoaded == 2 ) {
			return true;
		}

		// Whether it succeeds or fails, we don't want to try again
		$this->mTextLoaded = 2;

		if ( !$this->loadRevisionData() ) {
			return false;
		}

		if ( $this->mOldRev ) {
			$this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
			if ( $this->mOldContent === null ) {
				return false;
			}
		}

		if ( $this->mNewRev ) {
			$this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
			if ( $this->mNewContent === null ) {
				return false;
			}
		}

		return true;
	}

	/**
	 * Load the text of the new revision, not the old one
	 *
	 * @return bool
	 */
	public function loadNewText() {
		if ( $this->mTextLoaded >= 1 ) {
			return true;
		}

		$this->mTextLoaded = 1;

		if ( !$this->loadRevisionData() ) {
			return false;
		}

		$this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );

		return true;
	}

}

wikimedia / mediawiki

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includes/diff/DifferenceEngine.php (13 issues)

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