includes/Title.php

   1 <?php
   2 /**
   3  * Representation of a title within %MediaWiki.
   4  *
   5  * See title.txt
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along
  18  * with this program; if not, write to the Free Software Foundation, Inc.,
  19  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  20  * http://www.gnu.org/copyleft/gpl.html
  21  *
  22  * @file
  23  */
  24
  25 use Wikimedia\Rdbms\Database;
  26 use Wikimedia\Rdbms\IDatabase;
  27 use MediaWiki\Linker\LinkTarget;
  28 use MediaWiki\Interwiki\InterwikiLookup;
  29 use MediaWiki\MediaWikiServices;
  30
  31 /**
  32  * Represents a title within MediaWiki.
  33  * Optionally may contain an interwiki designation or namespace.
  34  * @note This class can fetch various kinds of data from the database;
  35  *       however, it does so inefficiently.
  36  * @note Consider using a TitleValue object instead. TitleValue is more lightweight
  37  *       and does not rely on global state or the database.
  38  */
  39 class Title implements LinkTarget {
  40         /** @var HashBagOStuff */
  41         static private $titleCache = null;
  42
  43         /**
  44          * Title::newFromText maintains a cache to avoid expensive re-normalization of
  45          * commonly used titles. On a batch operation this can become a memory leak
  46          * if not bounded. After hitting this many titles reset the cache.
  47          */
  48         const CACHE_MAX = 1000;
  49
  50         /**
  51          * Used to be GAID_FOR_UPDATE define. Used with getArticleID() and friends
  52          * to use the master DB
  53          */
  54         const GAID_FOR_UPDATE = 1;
  55
  56         /**
  57          * @name Private member variables
  58          * Please use the accessor functions instead.
  59          * @private
  60          */
  61         // @{
  62
  63         /** @var string Text form (spaces not underscores) of the main part */
  64         public $mTextform = '';
  65
  66         /** @var string URL-encoded form of the main part */
  67         public $mUrlform = '';
  68
  69         /** @var string Main part with underscores */
  70         public $mDbkeyform = '';
  71
  72         /** @var string Database key with the initial letter in the case specified by the user */
  73         protected $mUserCaseDBKey;
  74
  75         /** @var int Namespace index, i.e. one of the NS_xxxx constants */
  76         public $mNamespace = NS_MAIN;
  77
  78         /** @var string Interwiki prefix */
  79         public $mInterwiki = '';
  80
  81         /** @var bool Was this Title created from a string with a local interwiki prefix? */
  82         private $mLocalInterwiki = false;
  83
  84         /** @var string Title fragment (i.e. the bit after the #) */
  85         public $mFragment = '';
  86
  87         /** @var int Article ID, fetched from the link cache on demand */
  88         public $mArticleID = -1;
  89
  90         /** @var bool|int ID of most recent revision */
  91         protected $mLatestID = false;
  92
  93         /**
  94          * @var bool|string ID of the page's content model, i.e. one of the
  95          *   CONTENT_MODEL_XXX constants
  96          */
  97         private $mContentModel = false;
  98
  99         /**
 100          * @var bool If a content model was forced via setContentModel()
 101          *   this will be true to avoid having other code paths reset it
 102          */
 103         private $mForcedContentModel = false;
 104
 105         /** @var int Estimated number of revisions; null of not loaded */
 106         private $mEstimateRevisions;
 107
 108         /** @var array Array of groups allowed to edit this article */
 109         public $mRestrictions = [];
 110
 111         /** @var string|bool */
 112         protected $mOldRestrictions = false;
 113
 114         /** @var bool Cascade restrictions on this page to included templates and images? */
 115         public $mCascadeRestriction;
 116
 117         /** Caching the results of getCascadeProtectionSources */
 118         public $mCascadingRestrictions;
 119
 120         /** @var array When do the restrictions on this page expire? */
 121         protected $mRestrictionsExpiry = [];
 122
 123         /** @var bool Are cascading restrictions in effect on this page? */
 124         protected $mHasCascadingRestrictions;
 125
 126         /** @var array Where are the cascading restrictions coming from on this page? */
 127         public $mCascadeSources;
 128
 129         /** @var bool Boolean for initialisation on demand */
 130         public $mRestrictionsLoaded = false;
 131
 132         /** @var string Text form including namespace/interwiki, initialised on demand */
 133         protected $mPrefixedText = null;
 134
 135         /** @var mixed Cached value for getTitleProtection (create protection) */
 136         public $mTitleProtection;
 137
 138         /**
 139          * @var int Namespace index when there is no namespace. Don't change the
 140          *   following default, NS_MAIN is hardcoded in several places. See T2696.
 141          *   Zero except in {{transclusion}} tags.
 142          */
 143         public $mDefaultNamespace = NS_MAIN;
 144
 145         /** @var int The page length, 0 for special pages */
 146         protected $mLength = -1;
 147
 148         /** @var null Is the article at this title a redirect? */
 149         public $mRedirect = null;
 150
 151         /** @var array Associative array of user ID -> timestamp/false */
 152         private $mNotificationTimestamp = [];
 153
 154         /** @var bool Whether a page has any subpages */
 155         private $mHasSubpages;
 156
 157         /** @var bool The (string) language code of the page's language and content code. */
 158         private $mPageLanguage = false;
 159
 160         /** @var string|bool|null The page language code from the database, null if not saved in
 161          * the database or false if not loaded, yet. */
 162         private $mDbPageLanguage = false;
 163
 164         /** @var TitleValue A corresponding TitleValue object */
 165         private $mTitleValue = null;
 166
 167         /** @var bool Would deleting this page be a big deletion? */
 168         private $mIsBigDeletion = null;
 169         // @}
 170
 171         /**
 172          * B/C kludge: provide a TitleParser for use by Title.
 173          * Ideally, Title would have no methods that need this.
 174          * Avoid usage of this singleton by using TitleValue
 175          * and the associated services when possible.
 176          *
 177          * @return TitleFormatter
 178          */
 179         private static function getTitleFormatter() {
 180                 return MediaWikiServices::getInstance()->getTitleFormatter();
 181         }
 182
 183         /**
 184          * B/C kludge: provide an InterwikiLookup for use by Title.
 185          * Ideally, Title would have no methods that need this.
 186          * Avoid usage of this singleton by using TitleValue
 187          * and the associated services when possible.
 188          *
 189          * @return InterwikiLookup
 190          */
 191         private static function getInterwikiLookup() {
 192                 return MediaWikiServices::getInstance()->getInterwikiLookup();
 193         }
 194
 195         /**
 196          * @access protected
 197          */
 198         function __construct() {
 199         }
 200
 201         /**
 202          * Create a new Title from a prefixed DB key
 203          *
 204          * @param string $key The database key, which has underscores
 205          *      instead of spaces, possibly including namespace and
 206          *      interwiki prefixes
 207          * @return Title|null Title, or null on an error
 208          */
 209         public static function newFromDBkey( $key ) {
 210                 $t = new Title();
 211                 $t->mDbkeyform = $key;
 212
 213                 try {
 214                         $t->secureAndSplit();
 215                         return $t;
 216                 } catch ( MalformedTitleException $ex ) {
 217                         return null;
 218                 }
 219         }
 220
 221         /**
 222          * Create a new Title from a TitleValue
 223          *
 224          * @param TitleValue $titleValue Assumed to be safe.
 225          *
 226          * @return Title
 227          */
 228         public static function newFromTitleValue( TitleValue $titleValue ) {
 229                 return self::newFromLinkTarget( $titleValue );
 230         }
 231
 232         /**
 233          * Create a new Title from a LinkTarget
 234          *
 235          * @param LinkTarget $linkTarget Assumed to be safe.
 236          *
 237          * @return Title
 238          */
 239         public static function newFromLinkTarget( LinkTarget $linkTarget ) {
 240                 if ( $linkTarget instanceof Title ) {
 241                         // Special case if it's already a Title object
 242                         return $linkTarget;
 243                 }
 244                 return self::makeTitle(
 245                         $linkTarget->getNamespace(),
 246                         $linkTarget->getText(),
 247                         $linkTarget->getFragment(),
 248                         $linkTarget->getInterwiki()
 249                 );
 250         }
 251
 252         /**
 253          * Create a new Title from text, such as what one would find in a link. De-
 254          * codes any HTML entities in the text.
 255          *
 256          * Title objects returned by this method are guaranteed to be valid, and
 257          * thus return true from the isValid() method.
 258          *
 259          * @param string|int|null $text The link text; spaces, prefixes, and an
 260          *   initial ':' indicating the main namespace are accepted.
 261          * @param int $defaultNamespace The namespace to use if none is specified
 262          *   by a prefix.  If you want to force a specific namespace even if
 263          *   $text might begin with a namespace prefix, use makeTitle() or
 264          *   makeTitleSafe().
 265          * @throws InvalidArgumentException
 266          * @return Title|null Title or null on an error.
 267          */
 268         public static function newFromText( $text, $defaultNamespace = NS_MAIN ) {
 269                 // DWIM: Integers can be passed in here when page titles are used as array keys.
 270                 if ( $text !== null && !is_string( $text ) && !is_int( $text ) ) {
 271                         throw new InvalidArgumentException( '$text must be a string.' );
 272                 }
 273                 if ( $text === null ) {
 274                         return null;
 275                 }
 276
 277                 try {
 278                         return self::newFromTextThrow( strval( $text ), $defaultNamespace );
 279                 } catch ( MalformedTitleException $ex ) {
 280                         return null;
 281                 }
 282         }
 283
 284         /**
 285          * Like Title::newFromText(), but throws MalformedTitleException when the title is invalid,
 286          * rather than returning null.
 287          *
 288          * The exception subclasses encode detailed information about why the title is invalid.
 289          *
 290          * Title objects returned by this method are guaranteed to be valid, and
 291          * thus return true from the isValid() method.
 292          *
 293          * @see Title::newFromText
 294          *
 295          * @since 1.25
 296          * @param string $text Title text to check
 297          * @param int $defaultNamespace
 298          * @throws MalformedTitleException If the title is invalid
 299          * @return Title
 300          */
 301         public static function newFromTextThrow( $text, $defaultNamespace = NS_MAIN ) {
 302                 if ( is_object( $text ) ) {
 303                         throw new MWException( '$text must be a string, given an object' );
 304                 }
 305
 306                 $titleCache = self::getTitleCache();
 307
 308                 // Wiki pages often contain multiple links to the same page.
 309                 // Title normalization and parsing can become expensive on pages with many
 310                 // links, so we can save a little time by caching them.
 311                 // In theory these are value objects and won't get changed...
 312                 if ( $defaultNamespace == NS_MAIN ) {
 313                         $t = $titleCache->get( $text );
 314                         if ( $t ) {
 315                                 return $t;
 316                         }
 317                 }
 318
 319                 // Convert things like &eacute; &#257; or &#x3017; into normalized (T16952) text
 320                 $filteredText = Sanitizer::decodeCharReferencesAndNormalize( $text );
 321
 322                 $t = new Title();
 323                 $t->mDbkeyform = strtr( $filteredText, ' ', '_' );
 324                 $t->mDefaultNamespace = intval( $defaultNamespace );
 325
 326                 $t->secureAndSplit();
 327                 if ( $defaultNamespace == NS_MAIN ) {
 328                         $titleCache->set( $text, $t );
 329                 }
 330                 return $t;
 331         }
 332
 333         /**
 334          * THIS IS NOT THE FUNCTION YOU WANT. Use Title::newFromText().
 335          *
 336          * Example of wrong and broken code:
 337          * $title = Title::newFromURL( $wgRequest->getVal( 'title' ) );
 338          *
 339          * Example of right code:
 340          * $title = Title::newFromText( $wgRequest->getVal( 'title' ) );
 341          *
 342          * Create a new Title from URL-encoded text. Ensures that
 343          * the given title's length does not exceed the maximum.
 344          *
 345          * @param string $url The title, as might be taken from a URL
 346          * @return Title|null The new object, or null on an error
 347          */
 348         public static function newFromURL( $url ) {
 349                 $t = new Title();
 350
 351                 # For compatibility with old buggy URLs. "+" is usually not valid in titles,
 352                 # but some URLs used it as a space replacement and they still come
 353                 # from some external search tools.
 354                 if ( strpos( self::legalChars(), '+' ) === false ) {
 355                         $url = strtr( $url, '+', ' ' );
 356                 }
 357
 358                 $t->mDbkeyform = strtr( $url, ' ', '_' );
 359
 360                 try {
 361                         $t->secureAndSplit();
 362                         return $t;
 363                 } catch ( MalformedTitleException $ex ) {
 364                         return null;
 365                 }
 366         }
 367
 368         /**
 369          * @return HashBagOStuff
 370          */
 371         private static function getTitleCache() {
 372                 if ( self::$titleCache == null ) {
 373                         self::$titleCache = new HashBagOStuff( [ 'maxKeys' => self::CACHE_MAX ] );
 374                 }
 375                 return self::$titleCache;
 376         }
 377
 378         /**
 379          * Returns a list of fields that are to be selected for initializing Title
 380          * objects or LinkCache entries. Uses $wgContentHandlerUseDB to determine
 381          * whether to include page_content_model.
 382          *
 383          * @return array
 384          */
 385         protected static function getSelectFields() {
 386                 global $wgContentHandlerUseDB, $wgPageLanguageUseDB;
 387
 388                 $fields = [
 389                         'page_namespace', 'page_title', 'page_id',
 390                         'page_len', 'page_is_redirect', 'page_latest',
 391                 ];
 392
 393                 if ( $wgContentHandlerUseDB ) {
 394                         $fields[] = 'page_content_model';
 395                 }
 396
 397                 if ( $wgPageLanguageUseDB ) {
 398                         $fields[] = 'page_lang';
 399                 }
 400
 401                 return $fields;
 402         }
 403
 404         /**
 405          * Create a new Title from an article ID
 406          *
 407          * @param int $id The page_id corresponding to the Title to create
 408          * @param int $flags Use Title::GAID_FOR_UPDATE to use master
 409          * @return Title|null The new object, or null on an error
 410          */
 411         public static function newFromID( $id, $flags = 0 ) {
 412                 $db = ( $flags & self::GAID_FOR_UPDATE ) ? wfGetDB( DB_MASTER ) : wfGetDB( DB_REPLICA );
 413                 $row = $db->selectRow(
 414                         'page',
 415                         self::getSelectFields(),
 416                         [ 'page_id' => $id ],
 417                         __METHOD__
 418                 );
 419                 if ( $row !== false ) {
 420                         $title = self::newFromRow( $row );
 421                 } else {
 422                         $title = null;
 423                 }
 424                 return $title;
 425         }
 426
 427         /**
 428          * Make an array of titles from an array of IDs
 429          *
 430          * @param int[] $ids Array of IDs
 431          * @return Title[] Array of Titles
 432          */
 433         public static function newFromIDs( $ids ) {
 434                 if ( !count( $ids ) ) {
 435                         return [];
 436                 }
 437                 $dbr = wfGetDB( DB_REPLICA );
 438
 439                 $res = $dbr->select(
 440                         'page',
 441                         self::getSelectFields(),
 442                         [ 'page_id' => $ids ],
 443                         __METHOD__
 444                 );
 445
 446                 $titles = [];
 447                 foreach ( $res as $row ) {
 448                         $titles[] = self::newFromRow( $row );
 449                 }
 450                 return $titles;
 451         }
 452
 453         /**
 454          * Make a Title object from a DB row
 455          *
 456          * @param stdClass $row Object database row (needs at least page_title,page_namespace)
 457          * @return Title Corresponding Title
 458          */
 459         public static function newFromRow( $row ) {
 460                 $t = self::makeTitle( $row->page_namespace, $row->page_title );
 461                 $t->loadFromRow( $row );
 462                 return $t;
 463         }
 464
 465         /**
 466          * Load Title object fields from a DB row.
 467          * If false is given, the title will be treated as non-existing.
 468          *
 469          * @param stdClass|bool $row Database row
 470          */
 471         public function loadFromRow( $row ) {
 472                 if ( $row ) { // page found
 473                         if ( isset( $row->page_id ) ) {
 474                                 $this->mArticleID = (int)$row->page_id;
 475                         }
 476                         if ( isset( $row->page_len ) ) {
 477                                 $this->mLength = (int)$row->page_len;
 478                         }
 479                         if ( isset( $row->page_is_redirect ) ) {
 480                                 $this->mRedirect = (bool)$row->page_is_redirect;
 481                         }
 482                         if ( isset( $row->page_latest ) ) {
 483                                 $this->mLatestID = (int)$row->page_latest;
 484                         }
 485                         if ( !$this->mForcedContentModel && isset( $row->page_content_model ) ) {
 486                                 $this->mContentModel = strval( $row->page_content_model );
 487                         } elseif ( !$this->mForcedContentModel ) {
 488                                 $this->mContentModel = false; # initialized lazily in getContentModel()
 489                         }
 490                         if ( isset( $row->page_lang ) ) {
 491                                 $this->mDbPageLanguage = (string)$row->page_lang;
 492                         }
 493                         if ( isset( $row->page_restrictions ) ) {
 494                                 $this->mOldRestrictions = $row->page_restrictions;
 495                         }
 496                 } else { // page not found
 497                         $this->mArticleID = 0;
 498                         $this->mLength = 0;
 499                         $this->mRedirect = false;
 500                         $this->mLatestID = 0;
 501                         if ( !$this->mForcedContentModel ) {
 502                                 $this->mContentModel = false; # initialized lazily in getContentModel()
 503                         }
 504                 }
 505         }
 506
 507         /**
 508          * Create a new Title from a namespace index and a DB key.
 509          *
 510          * It's assumed that $ns and $title are safe, for instance when
 511          * they came directly from the database or a special page name,
 512          * not from user input.
 513          *
 514          * No validation is applied. For convenience, spaces are normalized
 515          * to underscores, so that e.g. user_text fields can be used directly.
 516          *
 517          * @note This method may return Title objects that are "invalid"
 518          * according to the isValid() method. This is usually caused by
 519          * configuration changes: e.g. a namespace that was once defined is
 520          * no longer configured, or a character that was once allowed in
 521          * titles is now forbidden.
 522          *
 523          * @param int $ns The namespace of the article
 524          * @param string $title The unprefixed database key form
 525          * @param string $fragment The link fragment (after the "#")
 526          * @param string $interwiki The interwiki prefix
 527          * @return Title The new object
 528          */
 529         public static function makeTitle( $ns, $title, $fragment = '', $interwiki = '' ) {
 530                 $t = new Title();
 531                 $t->mInterwiki = $interwiki;
 532                 $t->mFragment = $fragment;
 533                 $t->mNamespace = $ns = intval( $ns );
 534                 $t->mDbkeyform = strtr( $title, ' ', '_' );
 535                 $t->mArticleID = ( $ns >= 0 ) ? -1 : 0;
 536                 $t->mUrlform = wfUrlencode( $t->mDbkeyform );
 537                 $t->mTextform = strtr( $title, '_', ' ' );
 538                 $t->mContentModel = false; # initialized lazily in getContentModel()
 539                 return $t;
 540         }
 541
 542         /**
 543          * Create a new Title from a namespace index and a DB key.
 544          * The parameters will be checked for validity, which is a bit slower
 545          * than makeTitle() but safer for user-provided data.
 546          *
 547          * Title objects returned by makeTitleSafe() are guaranteed to be valid,
 548          * that is, they return true from the isValid() method. If no valid Title
 549          * can be constructed from the input, this method returns null.
 550          *
 551          * @param int $ns The namespace of the article
 552          * @param string $title Database key form
 553          * @param string $fragment The link fragment (after the "#")
 554          * @param string $interwiki Interwiki prefix
 555          * @return Title|null The new object, or null on an error
 556          */
 557         public static function makeTitleSafe( $ns, $title, $fragment = '', $interwiki = '' ) {
 558                 // NOTE: ideally, this would just call makeTitle() and then isValid(),
 559                 // but presently, that means more overhead on a potential performance hotspot.
 560
 561                 if ( !MWNamespace::exists( $ns ) ) {
 562                         return null;
 563                 }
 564
 565                 $t = new Title();
 566                 $t->mDbkeyform = self::makeName( $ns, $title, $fragment, $interwiki, true );
 567
 568                 try {
 569                         $t->secureAndSplit();
 570                         return $t;
 571                 } catch ( MalformedTitleException $ex ) {
 572                         return null;
 573                 }
 574         }
 575
 576         /**
 577          * Create a new Title for the Main Page
 578          *
 579          * @return Title The new object
 580          */
 581         public static function newMainPage() {
 582                 $title = self::newFromText( wfMessage( 'mainpage' )->inContentLanguage()->text() );
 583                 // Don't give fatal errors if the message is broken
 584                 if ( !$title ) {
 585                         $title = self::newFromText( 'Main Page' );
 586                 }
 587                 return $title;
 588         }
 589
 590         /**
 591          * Get the prefixed DB key associated with an ID
 592          *
 593          * @param int $id The page_id of the article
 594          * @return Title|null An object representing the article, or null if no such article was found
 595          */
 596         public static function nameOf( $id ) {
 597                 $dbr = wfGetDB( DB_REPLICA );
 598
 599                 $s = $dbr->selectRow(
 600                         'page',
 601                         [ 'page_namespace', 'page_title' ],
 602                         [ 'page_id' => $id ],
 603                         __METHOD__
 604                 );
 605                 if ( $s === false ) {
 606                         return null;
 607                 }
 608
 609                 $n = self::makeName( $s->page_namespace, $s->page_title );
 610                 return $n;
 611         }
 612
 613         /**
 614          * Get a regex character class describing the legal characters in a link
 615          *
 616          * @return string The list of characters, not delimited
 617          */
 618         public static function legalChars() {
 619                 global $wgLegalTitleChars;
 620                 return $wgLegalTitleChars;
 621         }
 622
 623         /**
 624          * Returns a simple regex that will match on characters and sequences invalid in titles.
 625          * Note that this doesn't pick up many things that could be wrong with titles, but that
 626          * replacing this regex with something valid will make many titles valid.
 627          *
 628          * @deprecated since 1.25, use MediaWikiTitleCodec::getTitleInvalidRegex() instead
 629          *
 630          * @return string Regex string
 631          */
 632         static function getTitleInvalidRegex() {
 633                 wfDeprecated( __METHOD__, '1.25' );
 634                 return MediaWikiTitleCodec::getTitleInvalidRegex();
 635         }
 636
 637         /**
 638          * Utility method for converting a character sequence from bytes to Unicode.
 639          *
 640          * Primary usecase being converting $wgLegalTitleChars to a sequence usable in
 641          * javascript, as PHP uses UTF-8 bytes where javascript uses Unicode code units.
 642          *
 643          * @param string $byteClass
 644          * @return string
 645          */
 646         public static function convertByteClassToUnicodeClass( $byteClass ) {
 647                 $length = strlen( $byteClass );
 648                 // Input token queue
 649                 $x0 = $x1 = $x2 = '';
 650                 // Decoded queue
 651                 $d0 = $d1 = $d2 = '';
 652                 // Decoded integer codepoints
 653                 $ord0 = $ord1 = $ord2 = 0;
 654                 // Re-encoded queue
 655                 $r0 = $r1 = $r2 = '';
 656                 // Output
 657                 $out = '';
 658                 // Flags
 659                 $allowUnicode = false;
 660                 for ( $pos = 0; $pos < $length; $pos++ ) {
 661                         // Shift the queues down
 662                         $x2 = $x1;
 663                         $x1 = $x0;
 664                         $d2 = $d1;
 665                         $d1 = $d0;
 666                         $ord2 = $ord1;
 667                         $ord1 = $ord0;
 668                         $r2 = $r1;
 669                         $r1 = $r0;
 670                         // Load the current input token and decoded values
 671                         $inChar = $byteClass[$pos];
 672                         if ( $inChar == '\\' ) {
 673                                 if ( preg_match( '/x([0-9a-fA-F]{2})/A', $byteClass, $m, 0, $pos + 1 ) ) {
 674                                         $x0 = $inChar . $m[0];
 675                                         $d0 = chr( hexdec( $m[1] ) );
 676                                         $pos += strlen( $m[0] );
 677                                 } elseif ( preg_match( '/[0-7]{3}/A', $byteClass, $m, 0, $pos + 1 ) ) {
 678                                         $x0 = $inChar . $m[0];
 679                                         $d0 = chr( octdec( $m[0] ) );
 680                                         $pos += strlen( $m[0] );
 681                                 } elseif ( $pos + 1 >= $length ) {
 682                                         $x0 = $d0 = '\\';
 683                                 } else {
 684                                         $d0 = $byteClass[$pos + 1];
 685                                         $x0 = $inChar . $d0;
 686                                         $pos += 1;
 687                                 }
 688                         } else {
 689                                 $x0 = $d0 = $inChar;
 690                         }
 691                         $ord0 = ord( $d0 );
 692                         // Load the current re-encoded value
 693                         if ( $ord0 < 32 || $ord0 == 0x7f ) {
 694                                 $r0 = sprintf( '\x%02x', $ord0 );
 695                         } elseif ( $ord0 >= 0x80 ) {
 696                                 // Allow unicode if a single high-bit character appears
 697                                 $r0 = sprintf( '\x%02x', $ord0 );
 698                                 $allowUnicode = true;
 699                         } elseif ( strpos( '-\\[]^', $d0 ) !== false ) {
 700                                 $r0 = '\\' . $d0;
 701                         } else {
 702                                 $r0 = $d0;
 703                         }
 704                         // Do the output
 705                         if ( $x0 !== '' && $x1 === '-' && $x2 !== '' ) {
 706                                 // Range
 707                                 if ( $ord2 > $ord0 ) {
 708                                         // Empty range
 709                                 } elseif ( $ord0 >= 0x80 ) {
 710                                         // Unicode range
 711                                         $allowUnicode = true;
 712                                         if ( $ord2 < 0x80 ) {
 713                                                 // Keep the non-unicode section of the range
 714                                                 $out .= "$r2-\\x7F";
 715                                         }
 716                                 } else {
 717                                         // Normal range
 718                                         $out .= "$r2-$r0";
 719                                 }
 720                                 // Reset state to the initial value
 721                                 $x0 = $x1 = $d0 = $d1 = $r0 = $r1 = '';
 722                         } elseif ( $ord2 < 0x80 ) {
 723                                 // ASCII character
 724                                 $out .= $r2;
 725                         }
 726                 }
 727                 if ( $ord1 < 0x80 ) {
 728                         $out .= $r1;
 729                 }
 730                 if ( $ord0 < 0x80 ) {
 731                         $out .= $r0;
 732                 }
 733                 if ( $allowUnicode ) {
 734                         $out .= '\u0080-\uFFFF';
 735                 }
 736                 return $out;
 737         }
 738
 739         /**
 740          * Make a prefixed DB key from a DB key and a namespace index
 741          *
 742          * @param int $ns Numerical representation of the namespace
 743          * @param string $title The DB key form the title
 744          * @param string $fragment The link fragment (after the "#")
 745          * @param string $interwiki The interwiki prefix
 746          * @param bool $canonicalNamespace If true, use the canonical name for
 747          *   $ns instead of the localized version.
 748          * @return string The prefixed form of the title
 749          */
 750         public static function makeName( $ns, $title, $fragment = '', $interwiki = '',
 751                 $canonicalNamespace = false
 752         ) {
 753                 global $wgContLang;
 754
 755                 if ( $canonicalNamespace ) {
 756                         $namespace = MWNamespace::getCanonicalName( $ns );
 757                 } else {
 758                         $namespace = $wgContLang->getNsText( $ns );
 759                 }
 760                 $name = $namespace == '' ? $title : "$namespace:$title";
 761                 if ( strval( $interwiki ) != '' ) {
 762                         $name = "$interwiki:$name";
 763                 }
 764                 if ( strval( $fragment ) != '' ) {
 765                         $name .= '#' . $fragment;
 766                 }
 767                 return $name;
 768         }
 769
 770         /**
 771          * Escape a text fragment, say from a link, for a URL
 772          *
 773          * @deprecated since 1.30, use Sanitizer::escapeIdForLink() or escapeIdForExternalInterwiki()
 774          *
 775          * @param string $fragment Containing a URL or link fragment (after the "#")
 776          * @return string Escaped string
 777          */
 778         static function escapeFragmentForURL( $fragment ) {
 779                 wfDeprecated( __METHOD__, '1.30' );
 780                 # Note that we don't urlencode the fragment.  urlencoded Unicode
 781                 # fragments appear not to work in IE (at least up to 7) or in at least
 782                 # one version of Opera 9.x.  The W3C validator, for one, doesn't seem
 783                 # to care if they aren't encoded.
 784                 return Sanitizer::escapeId( $fragment, 'noninitial' );
 785         }
 786
 787         /**
 788          * Callback for usort() to do title sorts by (namespace, title)
 789          *
 790          * @param LinkTarget $a
 791          * @param LinkTarget $b
 792          *
 793          * @return int Result of string comparison, or namespace comparison
 794          */
 795         public static function compare( LinkTarget $a, LinkTarget $b ) {
 796                 if ( $a->getNamespace() == $b->getNamespace() ) {
 797                         return strcmp( $a->getText(), $b->getText() );
 798                 } else {
 799                         return $a->getNamespace() - $b->getNamespace();
 800                 }
 801         }
 802
 803         /**
 804          * Returns true if the title is valid, false if it is invalid.
 805          *
 806          * Valid titles can be round-tripped via makeTitleSafe() and newFromText().
 807          * Invalid titles may get returned from makeTitle(), and it may be useful to
 808          * allow them to exist, e.g. in order to process log entries about pages in
 809          * namespaces that belong to extensions that are no longer installed.
 810          *
 811          * @note This method is relatively expensive. When constructing Title
 812          * objects that need to be valid, use an instantiator method that is guaranteed
 813          * to return valid titles, such as makeTitleSafe() or newFromText().
 814          *
 815          * @return bool
 816          */
 817         public function isValid() {
 818                 $ns = $this->getNamespace();
 819
 820                 if ( !MWNamespace::exists( $ns ) ) {
 821                         return false;
 822                 }
 823
 824                 try {
 825                         $parser = MediaWikiServices::getInstance()->getTitleParser();
 826                         $parser->parseTitle( $this->getDBkey(), $ns );
 827                         return true;
 828                 } catch ( MalformedTitleException $ex ) {
 829                         return false;
 830                 }
 831         }
 832
 833         /**
 834          * Determine whether the object refers to a page within
 835          * this project (either this wiki or a wiki with a local
 836          * interwiki, see https://www.mediawiki.org/wiki/Manual:Interwiki_table#iw_local )
 837          *
 838          * @return bool True if this is an in-project interwiki link or a wikilink, false otherwise
 839          */
 840         public function isLocal() {
 841                 if ( $this->isExternal() ) {
 842                         $iw = self::getInterwikiLookup()->fetch( $this->mInterwiki );
 843                         if ( $iw ) {
 844                                 return $iw->isLocal();
 845                         }
 846                 }
 847                 return true;
 848         }
 849
 850         /**
 851          * Is this Title interwiki?
 852          *
 853          * @return bool
 854          */
 855         public function isExternal() {
 856                 return $this->mInterwiki !== '';
 857         }
 858
 859         /**
 860          * Get the interwiki prefix
 861          *
 862          * Use Title::isExternal to check if a interwiki is set
 863          *
 864          * @return string Interwiki prefix
 865          */
 866         public function getInterwiki() {
 867                 return $this->mInterwiki;
 868         }
 869
 870         /**
 871          * Was this a local interwiki link?
 872          *
 873          * @return bool
 874          */
 875         public function wasLocalInterwiki() {
 876                 return $this->mLocalInterwiki;
 877         }
 878
 879         /**
 880          * Determine whether the object refers to a page within
 881          * this project and is transcludable.
 882          *
 883          * @return bool True if this is transcludable
 884          */
 885         public function isTrans() {
 886                 if ( !$this->isExternal() ) {
 887                         return false;
 888                 }
 889
 890                 return self::getInterwikiLookup()->fetch( $this->mInterwiki )->isTranscludable();
 891         }
 892
 893         /**
 894          * Returns the DB name of the distant wiki which owns the object.
 895          *
 896          * @return string|false The DB name
 897          */
 898         public function getTransWikiID() {
 899                 if ( !$this->isExternal() ) {
 900                         return false;
 901                 }
 902
 903                 return self::getInterwikiLookup()->fetch( $this->mInterwiki )->getWikiID();
 904         }
 905
 906         /**
 907          * Get a TitleValue object representing this Title.
 908          *
 909          * @note Not all valid Titles have a corresponding valid TitleValue
 910          * (e.g. TitleValues cannot represent page-local links that have a
 911          * fragment but no title text).
 912          *
 913          * @return TitleValue|null
 914          */
 915         public function getTitleValue() {
 916                 if ( $this->mTitleValue === null ) {
 917                         try {
 918                                 $this->mTitleValue = new TitleValue(
 919                                         $this->getNamespace(),
 920                                         $this->getDBkey(),
 921                                         $this->getFragment(),
 922                                         $this->getInterwiki()
 923                                 );
 924                         } catch ( InvalidArgumentException $ex ) {
 925                                 wfDebug( __METHOD__ . ': Can\'t create a TitleValue for [[' .
 926                                         $this->getPrefixedText() . ']]: ' . $ex->getMessage() . "\n" );
 927                         }
 928                 }
 929
 930                 return $this->mTitleValue;
 931         }
 932
 933         /**
 934          * Get the text form (spaces not underscores) of the main part
 935          *
 936          * @return string Main part of the title
 937          */
 938         public function getText() {
 939                 return $this->mTextform;
 940         }
 941
 942         /**
 943          * Get the URL-encoded form of the main part
 944          *
 945          * @return string Main part of the title, URL-encoded
 946          */
 947         public function getPartialURL() {
 948                 return $this->mUrlform;
 949         }
 950
 951         /**
 952          * Get the main part with underscores
 953          *
 954          * @return string Main part of the title, with underscores
 955          */
 956         public function getDBkey() {
 957                 return $this->mDbkeyform;
 958         }
 959
 960         /**
 961          * Get the DB key with the initial letter case as specified by the user
 962          *
 963          * @return string DB key
 964          */
 965         function getUserCaseDBKey() {
 966                 if ( !is_null( $this->mUserCaseDBKey ) ) {
 967                         return $this->mUserCaseDBKey;
 968                 } else {
 969                         // If created via makeTitle(), $this->mUserCaseDBKey is not set.
 970                         return $this->mDbkeyform;
 971                 }
 972         }
 973
 974         /**
 975          * Get the namespace index, i.e. one of the NS_xxxx constants.
 976          *
 977          * @return int Namespace index
 978          */
 979         public function getNamespace() {
 980                 return $this->mNamespace;
 981         }
 982
 983         /**
 984          * Get the page's content model id, see the CONTENT_MODEL_XXX constants.
 985          *
 986          * @param int $flags A bit field; may be Title::GAID_FOR_UPDATE to select for update
 987          * @return string Content model id
 988          */
 989         public function getContentModel( $flags = 0 ) {
 990                 if ( !$this->mForcedContentModel
 991                         && ( !$this->mContentModel || $flags === self::GAID_FOR_UPDATE )
 992                         && $this->getArticleID( $flags )
 993                 ) {
 994                         $linkCache = LinkCache::singleton();
 995                         $linkCache->addLinkObj( $this ); # in case we already had an article ID
 996                         $this->mContentModel = $linkCache->getGoodLinkFieldObj( $this, 'model' );
 997                 }
 998
 999                 if ( !$this->mContentModel ) {
1000                         $this->mContentModel = ContentHandler::getDefaultModelFor( $this );
1001                 }
1002
1003                 return $this->mContentModel;
1004         }
1005
1006         /**
1007          * Convenience method for checking a title's content model name
1008          *
1009          * @param string $id The content model ID (use the CONTENT_MODEL_XXX constants).
1010          * @return bool True if $this->getContentModel() == $id
1011          */
1012         public function hasContentModel( $id ) {
1013                 return $this->getContentModel() == $id;
1014         }
1015
1016         /**
1017          * Set a proposed content model for the page for permissions
1018          * checking. This does not actually change the content model
1019          * of a title!
1020          *
1021          * Additionally, you should make sure you've checked
1022          * ContentHandler::canBeUsedOn() first.
1023          *
1024          * @since 1.28
1025          * @param string $model CONTENT_MODEL_XXX constant
1026          */
1027         public function setContentModel( $model ) {
1028                 $this->mContentModel = $model;
1029                 $this->mForcedContentModel = true;
1030         }
1031
1032         /**
1033          * Get the namespace text
1034          *
1035          * @return string|false Namespace text
1036          */
1037         public function getNsText() {
1038                 if ( $this->isExternal() ) {
1039                         // This probably shouldn't even happen,
1040                         // but for interwiki transclusion it sometimes does.
1041                         // Use the canonical namespaces if possible to try to
1042                         // resolve a foreign namespace.
1043                         if ( MWNamespace::exists( $this->mNamespace ) ) {
1044                                 return MWNamespace::getCanonicalName( $this->mNamespace );
1045                         }
1046                 }
1047
1048                 try {
1049                         $formatter = self::getTitleFormatter();
1050                         return $formatter->getNamespaceName( $this->mNamespace, $this->mDbkeyform );
1051                 } catch ( InvalidArgumentException $ex ) {
1052                         wfDebug( __METHOD__ . ': ' . $ex->getMessage() . "\n" );
1053                         return false;
1054                 }
1055         }
1056
1057         /**
1058          * Get the namespace text of the subject (rather than talk) page
1059          *
1060          * @return string Namespace text
1061          */
1062         public function getSubjectNsText() {
1063                 global $wgContLang;
1064                 return $wgContLang->getNsText( MWNamespace::getSubject( $this->mNamespace ) );
1065         }
1066
1067         /**
1068          * Get the namespace text of the talk page
1069          *
1070          * @return string Namespace text
1071          */
1072         public function getTalkNsText() {
1073                 global $wgContLang;
1074                 return $wgContLang->getNsText( MWNamespace::getTalk( $this->mNamespace ) );
1075         }
1076
1077         /**
1078          * Can this title have a corresponding talk page?
1079          *
1080          * @deprecated since 1.30, use canHaveTalkPage() instead.
1081          *
1082          * @return bool True if this title either is a talk page or can have a talk page associated.
1083          */
1084         public function canTalk() {
1085                 return $this->canHaveTalkPage();
1086         }
1087
1088         /**
1089          * Can this title have a corresponding talk page?
1090          *
1091          * @see MWNamespace::hasTalkNamespace
1092          * @since 1.30
1093          *
1094          * @return bool True if this title either is a talk page or can have a talk page associated.
1095          */
1096         public function canHaveTalkPage() {
1097                 return MWNamespace::hasTalkNamespace( $this->mNamespace );
1098         }
1099
1100         /**
1101          * Is this in a namespace that allows actual pages?
1102          *
1103          * @return bool
1104          */
1105         public function canExist() {
1106                 return $this->mNamespace >= NS_MAIN;
1107         }
1108
1109         /**
1110          * Can this title be added to a user's watchlist?
1111          *
1112          * @return bool
1113          */
1114         public function isWatchable() {
1115                 return !$this->isExternal() && MWNamespace::isWatchable( $this->getNamespace() );
1116         }
1117
1118         /**
1119          * Returns true if this is a special page.
1120          *
1121          * @return bool
1122          */
1123         public function isSpecialPage() {
1124                 return $this->getNamespace() == NS_SPECIAL;
1125         }
1126
1127         /**
1128          * Returns true if this title resolves to the named special page
1129          *
1130          * @param string $name The special page name
1131          * @return bool
1132          */
1133         public function isSpecial( $name ) {
1134                 if ( $this->isSpecialPage() ) {
1135                         list( $thisName, /* $subpage */ ) = SpecialPageFactory::resolveAlias( $this->getDBkey() );
1136                         if ( $name == $thisName ) {
1137                                 return true;
1138                         }
1139                 }
1140                 return false;
1141         }
1142
1143         /**
1144          * If the Title refers to a special page alias which is not the local default, resolve
1145          * the alias, and localise the name as necessary.  Otherwise, return $this
1146          *
1147          * @return Title
1148          */
1149         public function fixSpecialName() {
1150                 if ( $this->isSpecialPage() ) {
1151                         list( $canonicalName, $par ) = SpecialPageFactory::resolveAlias( $this->mDbkeyform );
1152                         if ( $canonicalName ) {
1153                                 $localName = SpecialPageFactory::getLocalNameFor( $canonicalName, $par );
1154                                 if ( $localName != $this->mDbkeyform ) {
1155                                         return self::makeTitle( NS_SPECIAL, $localName );
1156                                 }
1157                         }
1158                 }
1159                 return $this;
1160         }
1161
1162         /**
1163          * Returns true if the title is inside the specified namespace.
1164          *
1165          * Please make use of this instead of comparing to getNamespace()
1166          * This function is much more resistant to changes we may make
1167          * to namespaces than code that makes direct comparisons.
1168          * @param int $ns The namespace
1169          * @return bool
1170          * @since 1.19
1171          */
1172         public function inNamespace( $ns ) {
1173                 return MWNamespace::equals( $this->getNamespace(), $ns );
1174         }
1175
1176         /**
1177          * Returns true if the title is inside one of the specified namespaces.
1178          *
1179          * @param int|int[] $namespaces,... The namespaces to check for
1180          * @return bool
1181          * @since 1.19
1182          */
1183         public function inNamespaces( /* ... */ ) {
1184                 $namespaces = func_get_args();
1185                 if ( count( $namespaces ) > 0 && is_array( $namespaces[0] ) ) {
1186                         $namespaces = $namespaces[0];
1187                 }
1188
1189                 foreach ( $namespaces as $ns ) {
1190                         if ( $this->inNamespace( $ns ) ) {
1191                                 return true;
1192                         }
1193                 }
1194
1195                 return false;
1196         }
1197
1198         /**
1199          * Returns true if the title has the same subject namespace as the
1200          * namespace specified.
1201          * For example this method will take NS_USER and return true if namespace
1202          * is either NS_USER or NS_USER_TALK since both of them have NS_USER
1203          * as their subject namespace.
1204          *
1205          * This is MUCH simpler than individually testing for equivalence
1206          * against both NS_USER and NS_USER_TALK, and is also forward compatible.
1207          * @since 1.19
1208          * @param int $ns
1209          * @return bool
1210          */
1211         public function hasSubjectNamespace( $ns ) {
1212                 return MWNamespace::subjectEquals( $this->getNamespace(), $ns );
1213         }
1214
1215         /**
1216          * Is this Title in a namespace which contains content?
1217          * In other words, is this a content page, for the purposes of calculating
1218          * statistics, etc?
1219          *
1220          * @return bool
1221          */
1222         public function isContentPage() {
1223                 return MWNamespace::isContent( $this->getNamespace() );
1224         }
1225
1226         /**
1227          * Would anybody with sufficient privileges be able to move this page?
1228          * Some pages just aren't movable.
1229          *
1230          * @return bool
1231          */
1232         public function isMovable() {
1233                 if ( !MWNamespace::isMovable( $this->getNamespace() ) || $this->isExternal() ) {
1234                         // Interwiki title or immovable namespace. Hooks don't get to override here
1235                         return false;
1236                 }
1237
1238                 $result = true;
1239                 Hooks::run( 'TitleIsMovable', [ $this, &$result ] );
1240                 return $result;
1241         }
1242
1243         /**
1244          * Is this the mainpage?
1245          * @note Title::newFromText seems to be sufficiently optimized by the title
1246          * cache that we don't need to over-optimize by doing direct comparisons and
1247          * accidentally creating new bugs where $title->equals( Title::newFromText() )
1248          * ends up reporting something differently than $title->isMainPage();
1249          *
1250          * @since 1.18
1251          * @return bool
1252          */
1253         public function isMainPage() {
1254                 return $this->equals( self::newMainPage() );
1255         }
1256
1257         /**
1258          * Is this a subpage?
1259          *
1260          * @return bool
1261          */
1262         public function isSubpage() {
1263                 return MWNamespace::hasSubpages( $this->mNamespace )
1264                         ? strpos( $this->getText(), '/' ) !== false
1265                         : false;
1266         }
1267
1268         /**
1269          * Is this a conversion table for the LanguageConverter?
1270          *
1271          * @return bool
1272          */
1273         public function isConversionTable() {
1274                 // @todo ConversionTable should become a separate content model.
1275
1276                 return $this->getNamespace() == NS_MEDIAWIKI &&
1277                         strpos( $this->getText(), 'Conversiontable/' ) === 0;
1278         }
1279
1280         /**
1281          * Does that page contain wikitext, or it is JS, CSS or whatever?
1282          *
1283          * @return bool
1284          */
1285         public function isWikitextPage() {
1286                 return $this->hasContentModel( CONTENT_MODEL_WIKITEXT );
1287         }
1288
1289         /**
1290          * Could this page contain custom CSS or JavaScript for the global UI.
1291          * This is generally true for pages in the MediaWiki namespace having CONTENT_MODEL_CSS
1292          * or CONTENT_MODEL_JAVASCRIPT.
1293          *
1294          * This method does *not* return true for per-user JS/CSS. Use isCssJsSubpage()
1295          * for that!
1296          *
1297          * Note that this method should not return true for pages that contain and
1298          * show "inactive" CSS or JS.
1299          *
1300          * @return bool
1301          * @todo FIXME: Rename to isSiteConfigPage() and remove deprecated hook
1302          */
1303         public function isCssOrJsPage() {
1304                 $isCssOrJsPage = NS_MEDIAWIKI == $this->mNamespace
1305                         && ( $this->hasContentModel( CONTENT_MODEL_CSS )
1306                                 || $this->hasContentModel( CONTENT_MODEL_JAVASCRIPT ) );
1307
1308                 return $isCssOrJsPage;
1309         }
1310
1311         /**
1312          * Is this a .css or .js subpage of a user page?
1313          * @return bool
1314          * @todo FIXME: Rename to isUserConfigPage()
1315          */
1316         public function isCssJsSubpage() {
1317                 return ( NS_USER == $this->mNamespace && $this->isSubpage()
1318                                 && ( $this->hasContentModel( CONTENT_MODEL_CSS )
1319                                         || $this->hasContentModel( CONTENT_MODEL_JAVASCRIPT ) ) );
1320         }
1321
1322         /**
1323          * Trim down a .css or .js subpage title to get the corresponding skin name
1324          *
1325          * @return string Containing skin name from .css or .js subpage title
1326          */
1327         public function getSkinFromCssJsSubpage() {
1328                 $subpage = explode( '/', $this->mTextform );
1329                 $subpage = $subpage[count( $subpage ) - 1];
1330                 $lastdot = strrpos( $subpage, '.' );
1331                 if ( $lastdot === false ) {
1332                         return $subpage; # Never happens: only called for names ending in '.css' or '.js'
1333                 }
1334                 return substr( $subpage, 0, $lastdot );
1335         }
1336
1337         /**
1338          * Is this a .css subpage of a user page?
1339          *
1340          * @return bool
1341          */
1342         public function isCssSubpage() {
1343                 return ( NS_USER == $this->mNamespace && $this->isSubpage()
1344                         && $this->hasContentModel( CONTENT_MODEL_CSS ) );
1345         }
1346
1347         /**
1348          * Is this a .js subpage of a user page?
1349          *
1350          * @return bool
1351          */
1352         public function isJsSubpage() {
1353                 return ( NS_USER == $this->mNamespace && $this->isSubpage()
1354                         && $this->hasContentModel( CONTENT_MODEL_JAVASCRIPT ) );
1355         }
1356
1357         /**
1358          * Is this a talk page of some sort?
1359          *
1360          * @return bool
1361          */
1362         public function isTalkPage() {
1363                 return MWNamespace::isTalk( $this->getNamespace() );
1364         }
1365
1366         /**
1367          * Get a Title object associated with the talk page of this article
1368          *
1369          * @return Title The object for the talk page
1370          */
1371         public function getTalkPage() {
1372                 return self::makeTitle( MWNamespace::getTalk( $this->getNamespace() ), $this->getDBkey() );
1373         }
1374
1375         /**
1376          * Get a Title object associated with the talk page of this article,
1377          * if such a talk page can exist.
1378          *
1379          * @since 1.30
1380          *
1381          * @return Title|null The object for the talk page,
1382          *         or null if no associated talk page can exist, according to canHaveTalkPage().
1383          */
1384         public function getTalkPageIfDefined() {
1385                 if ( !$this->canHaveTalkPage() ) {
1386                         return null;
1387                 }
1388
1389                 return $this->getTalkPage();
1390         }
1391
1392         /**
1393          * Get a title object associated with the subject page of this
1394          * talk page
1395          *
1396          * @return Title The object for the subject page
1397          */
1398         public function getSubjectPage() {
1399                 // Is this the same title?
1400                 $subjectNS = MWNamespace::getSubject( $this->getNamespace() );
1401                 if ( $this->getNamespace() == $subjectNS ) {
1402                         return $this;
1403                 }
1404                 return self::makeTitle( $subjectNS, $this->getDBkey() );
1405         }
1406
1407         /**
1408          * Get the other title for this page, if this is a subject page
1409          * get the talk page, if it is a subject page get the talk page
1410          *
1411          * @since 1.25
1412          * @throws MWException If the page doesn't have an other page
1413          * @return Title
1414          */
1415         public function getOtherPage() {
1416                 if ( $this->isSpecialPage() ) {
1417                         throw new MWException( 'Special pages cannot have other pages' );
1418                 }
1419                 if ( $this->isTalkPage() ) {
1420                         return $this->getSubjectPage();
1421                 } else {
1422                         if ( !$this->canHaveTalkPage() ) {
1423                                 throw new MWException( "{$this->getPrefixedText()} does not have an other page" );
1424                         }
1425                         return $this->getTalkPage();
1426                 }
1427         }
1428
1429         /**
1430          * Get the default namespace index, for when there is no namespace
1431          *
1432          * @return int Default namespace index
1433          */
1434         public function getDefaultNamespace() {
1435                 return $this->mDefaultNamespace;
1436         }
1437
1438         /**
1439          * Get the Title fragment (i.e.\ the bit after the #) in text form
1440          *
1441          * Use Title::hasFragment to check for a fragment
1442          *
1443          * @return string Title fragment
1444          */
1445         public function getFragment() {
1446                 return $this->mFragment;
1447         }
1448
1449         /**
1450          * Check if a Title fragment is set
1451          *
1452          * @return bool
1453          * @since 1.23
1454          */
1455         public function hasFragment() {
1456                 return $this->mFragment !== '';
1457         }
1458
1459         /**
1460          * Get the fragment in URL form, including the "#" character if there is one
1461          *
1462          * @return string Fragment in URL form
1463          */
1464         public function getFragmentForURL() {
1465                 if ( !$this->hasFragment() ) {
1466                         return '';
1467                 } elseif ( $this->isExternal() && !$this->getTransWikiID() ) {
1468                         return '#' . Sanitizer::escapeIdForExternalInterwiki( $this->getFragment() );
1469                 }
1470                 return '#' . Sanitizer::escapeIdForLink( $this->getFragment() );
1471         }
1472
1473         /**
1474          * Set the fragment for this title. Removes the first character from the
1475          * specified fragment before setting, so it assumes you're passing it with
1476          * an initial "#".
1477          *
1478          * Deprecated for public use, use Title::makeTitle() with fragment parameter,
1479          * or Title::createFragmentTarget().
1480          * Still in active use privately.
1481          *
1482          * @private
1483          * @param string $fragment Text
1484          */
1485         public function setFragment( $fragment ) {
1486                 $this->mFragment = strtr( substr( $fragment, 1 ), '_', ' ' );
1487         }
1488
1489         /**
1490          * Creates a new Title for a different fragment of the same page.
1491          *
1492          * @since 1.27
1493          * @param string $fragment
1494          * @return Title
1495          */
1496         public function createFragmentTarget( $fragment ) {
1497                 return self::makeTitle(
1498                         $this->getNamespace(),
1499                         $this->getText(),
1500                         $fragment,
1501                         $this->getInterwiki()
1502                 );
1503         }
1504
1505         /**
1506          * Prefix some arbitrary text with the namespace or interwiki prefix
1507          * of this object
1508          *
1509          * @param string $name The text
1510          * @return string The prefixed text
1511          */
1512         private function prefix( $name ) {
1513                 global $wgContLang;
1514
1515                 $p = '';
1516                 if ( $this->isExternal() ) {
1517                         $p = $this->mInterwiki . ':';
1518                 }
1519
1520                 if ( 0 != $this->mNamespace ) {
1521                         $nsText = $this->getNsText();
1522
1523                         if ( $nsText === false ) {
1524                                 // See T165149. Awkward, but better than erroneously linking to the main namespace.
1525                                 $nsText = $wgContLang->getNsText( NS_SPECIAL ) . ":Badtitle/NS{$this->mNamespace}";
1526                         }
1527
1528                         $p .= $nsText . ':';
1529                 }
1530                 return $p . $name;
1531         }
1532
1533         /**
1534          * Get the prefixed database key form
1535          *
1536          * @return string The prefixed title, with underscores and
1537          *  any interwiki and namespace prefixes
1538          */
1539         public function getPrefixedDBkey() {
1540                 $s = $this->prefix( $this->mDbkeyform );
1541                 $s = strtr( $s, ' ', '_' );
1542                 return $s;
1543         }
1544
1545         /**
1546          * Get the prefixed title with spaces.
1547          * This is the form usually used for display
1548          *
1549          * @return string The prefixed title, with spaces
1550          */
1551         public function getPrefixedText() {
1552                 if ( $this->mPrefixedText === null ) {
1553                         $s = $this->prefix( $this->mTextform );
1554                         $s = strtr( $s, '_', ' ' );
1555                         $this->mPrefixedText = $s;
1556                 }
1557                 return $this->mPrefixedText;
1558         }
1559
1560         /**
1561          * Return a string representation of this title
1562          *
1563          * @return string Representation of this title
1564          */
1565         public function __toString() {
1566                 return $this->getPrefixedText();
1567         }
1568
1569         /**
1570          * Get the prefixed title with spaces, plus any fragment
1571          * (part beginning with '#')
1572          *
1573          * @return string The prefixed title, with spaces and the fragment, including '#'
1574          */
1575         public function getFullText() {
1576                 $text = $this->getPrefixedText();
1577                 if ( $this->hasFragment() ) {
1578                         $text .= '#' . $this->getFragment();
1579                 }
1580                 return $text;
1581         }
1582
1583         /**
1584          * Get the root page name text without a namespace, i.e. the leftmost part before any slashes
1585          *
1586          * @par Example:
1587          * @code
1588          * Title::newFromText('User:Foo/Bar/Baz')->getRootText();
1589          * # returns: 'Foo'
1590          * @endcode
1591          *
1592          * @return string Root name
1593          * @since 1.20
1594          */
1595         public function getRootText() {
1596                 if ( !MWNamespace::hasSubpages( $this->mNamespace ) ) {
1597                         return $this->getText();
1598                 }
1599
1600                 return strtok( $this->getText(), '/' );
1601         }
1602
1603         /**
1604          * Get the root page name title, i.e. the leftmost part before any slashes
1605          *
1606          * @par Example:
1607          * @code
1608          * Title::newFromText('User:Foo/Bar/Baz')->getRootTitle();
1609          * # returns: Title{User:Foo}
1610          * @endcode
1611          *
1612          * @return Title Root title
1613          * @since 1.20
1614          */
1615         public function getRootTitle() {
1616                 return self::makeTitle( $this->getNamespace(), $this->getRootText() );
1617         }
1618
1619         /**
1620          * Get the base page name without a namespace, i.e. the part before the subpage name
1621          *
1622          * @par Example:
1623          * @code
1624          * Title::newFromText('User:Foo/Bar/Baz')->getBaseText();
1625          * # returns: 'Foo/Bar'
1626          * @endcode
1627          *
1628          * @return string Base name
1629          */
1630         public function getBaseText() {
1631                 if ( !MWNamespace::hasSubpages( $this->mNamespace ) ) {
1632                         return $this->getText();
1633                 }
1634
1635                 $parts = explode( '/', $this->getText() );
1636                 # Don't discard the real title if there's no subpage involved
1637                 if ( count( $parts ) > 1 ) {
1638                         unset( $parts[count( $parts ) - 1] );
1639                 }
1640                 return implode( '/', $parts );
1641         }
1642
1643         /**
1644          * Get the base page name title, i.e. the part before the subpage name
1645          *
1646          * @par Example:
1647          * @code
1648          * Title::newFromText('User:Foo/Bar/Baz')->getBaseTitle();
1649          * # returns: Title{User:Foo/Bar}
1650          * @endcode
1651          *
1652          * @return Title Base title
1653          * @since 1.20
1654          */
1655         public function getBaseTitle() {
1656                 return self::makeTitle( $this->getNamespace(), $this->getBaseText() );
1657         }
1658
1659         /**
1660          * Get the lowest-level subpage name, i.e. the rightmost part after any slashes
1661          *
1662          * @par Example:
1663          * @code
1664          * Title::newFromText('User:Foo/Bar/Baz')->getSubpageText();
1665          * # returns: "Baz"
1666          * @endcode
1667          *
1668          * @return string Subpage name
1669          */
1670         public function getSubpageText() {
1671                 if ( !MWNamespace::hasSubpages( $this->mNamespace ) ) {
1672                         return $this->mTextform;
1673                 }
1674                 $parts = explode( '/', $this->mTextform );
1675                 return $parts[count( $parts ) - 1];
1676         }
1677
1678         /**
1679          * Get the title for a subpage of the current page
1680          *
1681          * @par Example:
1682          * @code
1683          * Title::newFromText('User:Foo/Bar/Baz')->getSubpage("Asdf");
1684          * # returns: Title{User:Foo/Bar/Baz/Asdf}
1685          * @endcode
1686          *
1687          * @param string $text The subpage name to add to the title
1688          * @return Title Subpage title
1689          * @since 1.20
1690          */
1691         public function getSubpage( $text ) {
1692                 return self::makeTitleSafe( $this->getNamespace(), $this->getText() . '/' . $text );
1693         }
1694
1695         /**
1696          * Get a URL-encoded form of the subpage text
1697          *
1698          * @return string URL-encoded subpage name
1699          */
1700         public function getSubpageUrlForm() {
1701                 $text = $this->getSubpageText();
1702                 $text = wfUrlencode( strtr( $text, ' ', '_' ) );
1703                 return $text;
1704         }
1705
1706         /**
1707          * Get a URL-encoded title (not an actual URL) including interwiki
1708          *
1709          * @return string The URL-encoded form
1710          */
1711         public function getPrefixedURL() {
1712                 $s = $this->prefix( $this->mDbkeyform );
1713                 $s = wfUrlencode( strtr( $s, ' ', '_' ) );
1714                 return $s;
1715         }
1716
1717         /**
1718          * Helper to fix up the get{Canonical,Full,Link,Local,Internal}URL args
1719          * get{Canonical,Full,Link,Local,Internal}URL methods accepted an optional
1720          * second argument named variant. This was deprecated in favor
1721          * of passing an array of option with a "variant" key
1722          * Once $query2 is removed for good, this helper can be dropped
1723          * and the wfArrayToCgi moved to getLocalURL();
1724          *
1725          * @since 1.19 (r105919)
1726          * @param array|string $query
1727          * @param string|string[]|bool $query2
1728          * @return string
1729          */
1730         private static function fixUrlQueryArgs( $query, $query2 = false ) {
1731                 if ( $query2 !== false ) {
1732                         wfDeprecated( "Title::get{Canonical,Full,Link,Local,Internal}URL " .
1733                                 "method called with a second parameter is deprecated. Add your " .
1734                                 "parameter to an array passed as the first parameter.", "1.19" );
1735                 }
1736                 if ( is_array( $query ) ) {
1737                         $query = wfArrayToCgi( $query );
1738                 }
1739                 if ( $query2 ) {
1740                         if ( is_string( $query2 ) ) {
1741                                 // $query2 is a string, we will consider this to be
1742                                 // a deprecated $variant argument and add it to the query
1743                                 $query2 = wfArrayToCgi( [ 'variant' => $query2 ] );
1744                         } else {
1745                                 $query2 = wfArrayToCgi( $query2 );
1746                         }
1747                         // If we have $query content add a & to it first
1748                         if ( $query ) {
1749                                 $query .= '&';
1750                         }
1751                         // Now append the queries together
1752                         $query .= $query2;
1753                 }
1754                 return $query;
1755         }
1756
1757         /**
1758          * Get a real URL referring to this title, with interwiki link and
1759          * fragment
1760          *
1761          * @see self::getLocalURL for the arguments.
1762          * @see wfExpandUrl
1763          * @param string|string[] $query
1764          * @param string|string[]|bool $query2
1765          * @param string $proto Protocol type to use in URL
1766          * @return string The URL
1767          */
1768         public function getFullURL( $query = '', $query2 = false, $proto = PROTO_RELATIVE ) {
1769                 $query = self::fixUrlQueryArgs( $query, $query2 );
1770
1771                 # Hand off all the decisions on urls to getLocalURL
1772                 $url = $this->getLocalURL( $query );
1773
1774                 # Expand the url to make it a full url. Note that getLocalURL has the
1775                 # potential to output full urls for a variety of reasons, so we use
1776                 # wfExpandUrl instead of simply prepending $wgServer
1777                 $url = wfExpandUrl( $url, $proto );
1778
1779                 # Finally, add the fragment.
1780                 $url .= $this->getFragmentForURL();
1781                 // Avoid PHP 7.1 warning from passing $this by reference
1782                 $titleRef = $this;
1783                 Hooks::run( 'GetFullURL', [ &$titleRef, &$url, $query ] );
1784                 return $url;
1785         }
1786
1787         /**
1788          * Get a url appropriate for making redirects based on an untrusted url arg
1789          *
1790          * This is basically the same as getFullUrl(), but in the case of external
1791          * interwikis, we send the user to a landing page, to prevent possible
1792          * phishing attacks and the like.
1793          *
1794          * @note Uses current protocol by default, since technically relative urls
1795          *   aren't allowed in redirects per HTTP spec, so this is not suitable for
1796          *   places where the url gets cached, as might pollute between
1797          *   https and non-https users.
1798          * @see self::getLocalURL for the arguments.
1799          * @param array|string $query
1800          * @param string $proto Protocol type to use in URL
1801          * @return string A url suitable to use in an HTTP location header.
1802          */
1803         public function getFullUrlForRedirect( $query = '', $proto = PROTO_CURRENT ) {
1804                 $target = $this;
1805                 if ( $this->isExternal() ) {
1806                         $target = SpecialPage::getTitleFor(
1807                                 'GoToInterwiki',
1808                                 $this->getPrefixedDBKey()
1809                         );
1810                 }
1811                 return $target->getFullUrl( $query, false, $proto );
1812         }
1813
1814         /**
1815          * Get a URL with no fragment or server name (relative URL) from a Title object.
1816          * If this page is generated with action=render, however,
1817          * $wgServer is prepended to make an absolute URL.
1818          *
1819          * @see self::getFullURL to always get an absolute URL.
1820          * @see self::getLinkURL to always get a URL that's the simplest URL that will be
1821          *  valid to link, locally, to the current Title.
1822          * @see self::newFromText to produce a Title object.
1823          *
1824          * @param string|string[] $query An optional query string,
1825          *   not used for interwiki links. Can be specified as an associative array as well,
1826          *   e.g., array( 'action' => 'edit' ) (keys and values will be URL-escaped).
1827          *   Some query patterns will trigger various shorturl path replacements.
1828          * @param string|string[]|bool $query2 An optional secondary query array. This one MUST
1829          *   be an array. If a string is passed it will be interpreted as a deprecated
1830          *   variant argument and urlencoded into a variant= argument.
1831          *   This second query argument will be added to the $query
1832          *   The second parameter is deprecated since 1.19. Pass it as a key,value
1833          *   pair in the first parameter array instead.
1834          *
1835          * @return string String of the URL.
1836          */
1837         public function getLocalURL( $query = '', $query2 = false ) {
1838                 global $wgArticlePath, $wgScript, $wgServer, $wgRequest;
1839
1840                 $query = self::fixUrlQueryArgs( $query, $query2 );
1841
1842                 $interwiki = self::getInterwikiLookup()->fetch( $this->mInterwiki );
1843                 if ( $interwiki ) {
1844                         $namespace = $this->getNsText();
1845                         if ( $namespace != '' ) {
1846                                 # Can this actually happen? Interwikis shouldn't be parsed.
1847                                 # Yes! It can in interwiki transclusion. But... it probably shouldn't.
1848                                 $namespace .= ':';
1849                         }
1850                         $url = $interwiki->getURL( $namespace . $this->getDBkey() );
1851                         $url = wfAppendQuery( $url, $query );
1852                 } else {
1853                         $dbkey = wfUrlencode( $this->getPrefixedDBkey() );
1854                         if ( $query == '' ) {
1855                                 $url = str_replace( '$1', $dbkey, $wgArticlePath );
1856                                 // Avoid PHP 7.1 warning from passing $this by reference
1857                                 $titleRef = $this;
1858                                 Hooks::run( 'GetLocalURL::Article', [ &$titleRef, &$url ] );
1859                         } else {
1860                                 global $wgVariantArticlePath, $wgActionPaths, $wgContLang;
1861                                 $url = false;
1862                                 $matches = [];
1863
1864                                 if ( !empty( $wgActionPaths )
1865                                         && preg_match( '/^(.*&|)action=([^&]*)(&(.*)|)$/', $query, $matches )
1866                                 ) {
1867                                         $action = urldecode( $matches[2] );
1868                                         if ( isset( $wgActionPaths[$action] ) ) {
1869                                                 $query = $matches[1];
1870                                                 if ( isset( $matches[4] ) ) {
1871                                                         $query .= $matches[4];
1872                                                 }
1873                                                 $url = str_replace( '$1', $dbkey, $wgActionPaths[$action] );
1874                                                 if ( $query != '' ) {
1875                                                         $url = wfAppendQuery( $url, $query );
1876                                                 }
1877                                         }
1878                                 }
1879
1880                                 if ( $url === false
1881                                         && $wgVariantArticlePath
1882                                         && preg_match( '/^variant=([^&]*)$/', $query, $matches )
1883                                         && $this->getPageLanguage()->equals( $wgContLang )
1884                                         && $this->getPageLanguage()->hasVariants()
1885                                 ) {
1886                                         $variant = urldecode( $matches[1] );
1887                                         if ( $this->getPageLanguage()->hasVariant( $variant ) ) {
1888                                                 // Only do the variant replacement if the given variant is a valid
1889                                                 // variant for the page's language.
1890                                                 $url = str_replace( '$2', urlencode( $variant ), $wgVariantArticlePath );
1891                                                 $url = str_replace( '$1', $dbkey, $url );
1892                                         }
1893                                 }
1894
1895                                 if ( $url === false ) {
1896                                         if ( $query == '-' ) {
1897                                                 $query = '';
1898                                         }
1899                                         $url = "{$wgScript}?title={$dbkey}&{$query}";
1900                                 }
1901                         }
1902                         // Avoid PHP 7.1 warning from passing $this by reference
1903                         $titleRef = $this;
1904                         Hooks::run( 'GetLocalURL::Internal', [ &$titleRef, &$url, $query ] );
1905
1906                         // @todo FIXME: This causes breakage in various places when we
1907                         // actually expected a local URL and end up with dupe prefixes.
1908                         if ( $wgRequest->getVal( 'action' ) == 'render' ) {
1909                                 $url = $wgServer . $url;
1910                         }
1911                 }
1912                 // Avoid PHP 7.1 warning from passing $this by reference
1913                 $titleRef = $this;
1914                 Hooks::run( 'GetLocalURL', [ &$titleRef, &$url, $query ] );
1915                 return $url;
1916         }
1917
1918         /**
1919          * Get a URL that's the simplest URL that will be valid to link, locally,
1920          * to the current Title.  It includes the fragment, but does not include
1921          * the server unless action=render is used (or the link is external).  If
1922          * there's a fragment but the prefixed text is empty, we just return a link
1923          * to the fragment.
1924          *
1925          * The result obviously should not be URL-escaped, but does need to be
1926          * HTML-escaped if it's being output in HTML.
1927          *
1928          * @param string|string[] $query
1929          * @param bool $query2
1930          * @param string|int|bool $proto A PROTO_* constant on how the URL should be expanded,
1931          *                               or false (default) for no expansion
1932          * @see self::getLocalURL for the arguments.
1933          * @return string The URL
1934          */
1935         public function getLinkURL( $query = '', $query2 = false, $proto = false ) {
1936                 if ( $this->isExternal() || $proto !== false ) {
1937                         $ret = $this->getFullURL( $query, $query2, $proto );
1938                 } elseif ( $this->getPrefixedText() === '' && $this->hasFragment() ) {
1939                         $ret = $this->getFragmentForURL();
1940                 } else {
1941                         $ret = $this->getLocalURL( $query, $query2 ) . $this->getFragmentForURL();
1942                 }
1943                 return $ret;
1944         }
1945
1946         /**
1947          * Get the URL form for an internal link.
1948          * - Used in various CDN-related code, in case we have a different
1949          * internal hostname for the server from the exposed one.
1950          *
1951          * This uses $wgInternalServer to qualify the path, or $wgServer
1952          * if $wgInternalServer is not set. If the server variable used is
1953          * protocol-relative, the URL will be expanded to http://
1954          *
1955          * @see self::getLocalURL for the arguments.
1956          * @param string $query
1957          * @param string|bool $query2
1958          * @return string The URL
1959          */
1960         public function getInternalURL( $query = '', $query2 = false ) {
1961                 global $wgInternalServer, $wgServer;
1962                 $query = self::fixUrlQueryArgs( $query, $query2 );
1963                 $server = $wgInternalServer !== false ? $wgInternalServer : $wgServer;
1964                 $url = wfExpandUrl( $server . $this->getLocalURL( $query ), PROTO_HTTP );
1965                 // Avoid PHP 7.1 warning from passing $this by reference
1966                 $titleRef = $this;
1967                 Hooks::run( 'GetInternalURL', [ &$titleRef, &$url, $query ] );
1968                 return $url;
1969         }
1970
1971         /**
1972          * Get the URL for a canonical link, for use in things like IRC and
1973          * e-mail notifications. Uses $wgCanonicalServer and the
1974          * GetCanonicalURL hook.
1975          *
1976          * NOTE: Unlike getInternalURL(), the canonical URL includes the fragment
1977          *
1978          * @see self::getLocalURL for the arguments.
1979          * @param string $query
1980          * @param string|bool $query2
1981          * @return string The URL
1982          * @since 1.18
1983          */
1984         public function getCanonicalURL( $query = '', $query2 = false ) {
1985                 $query = self::fixUrlQueryArgs( $query, $query2 );
1986                 $url = wfExpandUrl( $this->getLocalURL( $query ) . $this->getFragmentForURL(), PROTO_CANONICAL );
1987                 // Avoid PHP 7.1 warning from passing $this by reference
1988                 $titleRef = $this;
1989                 Hooks::run( 'GetCanonicalURL', [ &$titleRef, &$url, $query ] );
1990                 return $url;
1991         }
1992
1993         /**
1994          * Get the edit URL for this Title
1995          *
1996          * @return string The URL, or a null string if this is an interwiki link
1997          */
1998         public function getEditURL() {
1999                 if ( $this->isExternal() ) {
2000                         return '';
2001                 }
2002                 $s = $this->getLocalURL( 'action=edit' );
2003
2004                 return $s;
2005         }
2006
2007         /**
2008          * Can $user perform $action on this page?
2009          * This skips potentially expensive cascading permission checks
2010          * as well as avoids expensive error formatting
2011          *
2012          * Suitable for use for nonessential UI controls in common cases, but
2013          * _not_ for functional access control.
2014          *
2015          * May provide false positives, but should never provide a false negative.
2016          *
2017          * @param string $action Action that permission needs to be checked for
2018          * @param User $user User to check (since 1.19); $wgUser will be used if not provided.
2019          * @return bool
2020          */
2021         public function quickUserCan( $action, $user = null ) {
2022                 return $this->userCan( $action, $user, false );
2023         }
2024
2025         /**
2026          * Can $user perform $action on this page?
2027          *
2028          * @param string $action Action that permission needs to be checked for
2029          * @param User $user User to check (since 1.19); $wgUser will be used if not
2030          *   provided.
2031          * @param string $rigor Same format as Title::getUserPermissionsErrors()
2032          * @return bool
2033          */
2034         public function userCan( $action, $user = null, $rigor = 'secure' ) {
2035                 if ( !$user instanceof User ) {
2036                         global $wgUser;
2037                         $user = $wgUser;
2038                 }
2039
2040                 return !count( $this->getUserPermissionsErrorsInternal( $action, $user, $rigor, true ) );
2041         }
2042
2043         /**
2044          * Can $user perform $action on this page?
2045          *
2046          * @todo FIXME: This *does not* check throttles (User::pingLimiter()).
2047          *
2048          * @param string $action Action that permission needs to be checked for
2049          * @param User $user User to check
2050          * @param string $rigor One of (quick,full,secure)
2051          *   - quick  : does cheap permission checks from replica DBs (usable for GUI creation)
2052          *   - full   : does cheap and expensive checks possibly from a replica DB
2053          *   - secure : does cheap and expensive checks, using the master as needed
2054          * @param array $ignoreErrors Array of Strings Set this to a list of message keys
2055          *   whose corresponding errors may be ignored.
2056          * @return array Array of arrays of the arguments to wfMessage to explain permissions problems.
2057          */
2058         public function getUserPermissionsErrors(
2059                 $action, $user, $rigor = 'secure', $ignoreErrors = []
2060         ) {
2061                 $errors = $this->getUserPermissionsErrorsInternal( $action, $user, $rigor );
2062
2063                 // Remove the errors being ignored.
2064                 foreach ( $errors as $index => $error ) {
2065                         $errKey = is_array( $error ) ? $error[0] : $error;
2066
2067                         if ( in_array( $errKey, $ignoreErrors ) ) {
2068                                 unset( $errors[$index] );
2069                         }
2070                         if ( $errKey instanceof MessageSpecifier && in_array( $errKey->getKey(), $ignoreErrors ) ) {
2071                                 unset( $errors[$index] );
2072                         }
2073                 }
2074
2075                 return $errors;
2076         }
2077
2078         /**
2079          * Permissions checks that fail most often, and which are easiest to test.
2080          *
2081          * @param string $action The action to check
2082          * @param User $user User to check
2083          * @param array $errors List of current errors
2084          * @param string $rigor Same format as Title::getUserPermissionsErrors()
2085          * @param bool $short Short circuit on first error
2086          *
2087          * @return array List of errors
2088          */
2089         private function checkQuickPermissions( $action, $user, $errors, $rigor, $short ) {
2090                 if ( !Hooks::run( 'TitleQuickPermissions',
2091                         [ $this, $user, $action, &$errors, ( $rigor !== 'quick' ), $short ] )
2092                 ) {
2093                         return $errors;
2094                 }
2095
2096                 if ( $action == 'create' ) {
2097                         if (
2098                                 ( $this->isTalkPage() && !$user->isAllowed( 'createtalk' ) ) ||
2099                                 ( !$this->isTalkPage() && !$user->isAllowed( 'createpage' ) )
2100                         ) {
2101                                 $errors[] = $user->isAnon() ? [ 'nocreatetext' ] : [ 'nocreate-loggedin' ];
2102                         }
2103                 } elseif ( $action == 'move' ) {
2104                         if ( !$user->isAllowed( 'move-rootuserpages' )
2105                                         && $this->mNamespace == NS_USER && !$this->isSubpage() ) {
2106                                 // Show user page-specific message only if the user can move other pages
2107                                 $errors[] = [ 'cant-move-user-page' ];
2108                         }
2109
2110                         // Check if user is allowed to move files if it's a file
2111                         if ( $this->mNamespace == NS_FILE && !$user->isAllowed( 'movefile' ) ) {
2112                                 $errors[] = [ 'movenotallowedfile' ];
2113                         }
2114
2115                         // Check if user is allowed to move category pages if it's a category page
2116                         if ( $this->mNamespace == NS_CATEGORY && !$user->isAllowed( 'move-categorypages' ) ) {
2117                                 $errors[] = [ 'cant-move-category-page' ];
2118                         }
2119
2120                         if ( !$user->isAllowed( 'move' ) ) {
2121                                 // User can't move anything
2122                                 $userCanMove = User::groupHasPermission( 'user', 'move' );
2123                                 $autoconfirmedCanMove = User::groupHasPermission( 'autoconfirmed', 'move' );
2124                                 if ( $user->isAnon() && ( $userCanMove || $autoconfirmedCanMove ) ) {
2125                                         // custom message if logged-in users without any special rights can move
2126                                         $errors[] = [ 'movenologintext' ];
2127                                 } else {
2128                                         $errors[] = [ 'movenotallowed' ];
2129                                 }
2130                         }
2131                 } elseif ( $action == 'move-target' ) {
2132                         if ( !$user->isAllowed( 'move' ) ) {
2133                                 // User can't move anything
2134                                 $errors[] = [ 'movenotallowed' ];
2135                         } elseif ( !$user->isAllowed( 'move-rootuserpages' )
2136                                         && $this->mNamespace == NS_USER && !$this->isSubpage() ) {
2137                                 // Show user page-specific message only if the user can move other pages
2138                                 $errors[] = [ 'cant-move-to-user-page' ];
2139                         } elseif ( !$user->isAllowed( 'move-categorypages' )
2140                                         && $this->mNamespace == NS_CATEGORY ) {
2141                                 // Show category page-specific message only if the user can move other pages
2142                                 $errors[] = [ 'cant-move-to-category-page' ];
2143                         }
2144                 } elseif ( !$user->isAllowed( $action ) ) {
2145                         $errors[] = $this->missingPermissionError( $action, $short );
2146                 }
2147
2148                 return $errors;
2149         }
2150
2151         /**
2152          * Add the resulting error code to the errors array
2153          *
2154          * @param array $errors List of current errors
2155          * @param array $result Result of errors
2156          *
2157          * @return array List of errors
2158          */
2159         private function resultToError( $errors, $result ) {
2160                 if ( is_array( $result ) && count( $result ) && !is_array( $result[0] ) ) {
2161                         // A single array representing an error
2162                         $errors[] = $result;
2163                 } elseif ( is_array( $result ) && is_array( $result[0] ) ) {
2164                         // A nested array representing multiple errors
2165                         $errors = array_merge( $errors, $result );
2166                 } elseif ( $result !== '' && is_string( $result ) ) {
2167                         // A string representing a message-id
2168                         $errors[] = [ $result ];
2169                 } elseif ( $result instanceof MessageSpecifier ) {
2170                         // A message specifier representing an error
2171                         $errors[] = [ $result ];
2172                 } elseif ( $result === false ) {
2173                         // a generic "We don't want them to do that"
2174                         $errors[] = [ 'badaccess-group0' ];
2175                 }
2176                 return $errors;
2177         }
2178
2179         /**
2180          * Check various permission hooks
2181          *
2182          * @param string $action The action to check
2183          * @param User $user User to check
2184          * @param array $errors List of current errors
2185          * @param string $rigor Same format as Title::getUserPermissionsErrors()
2186          * @param bool $short Short circuit on first error
2187          *
2188          * @return array List of errors
2189          */
2190         private function checkPermissionHooks( $action, $user, $errors, $rigor, $short ) {
2191                 // Use getUserPermissionsErrors instead
2192                 $result = '';
2193                 // Avoid PHP 7.1 warning from passing $this by reference
2194                 $titleRef = $this;
2195                 if ( !Hooks::run( 'userCan', [ &$titleRef, &$user, $action, &$result ] ) ) {
2196                         return $result ? [] : [ [ 'badaccess-group0' ] ];
2197                 }
2198                 // Check getUserPermissionsErrors hook
2199                 // Avoid PHP 7.1 warning from passing $this by reference
2200                 $titleRef = $this;
2201                 if ( !Hooks::run( 'getUserPermissionsErrors', [ &$titleRef, &$user, $action, &$result ] ) ) {
2202                         $errors = $this->resultToError( $errors, $result );
2203                 }
2204                 // Check getUserPermissionsErrorsExpensive hook
2205                 if (
2206                         $rigor !== 'quick'
2207                         && !( $short && count( $errors ) > 0 )
2208                         && !Hooks::run( 'getUserPermissionsErrorsExpensive', [ &$titleRef, &$user, $action, &$result ] )
2209                 ) {
2210                         $errors = $this->resultToError( $errors, $result );
2211                 }
2212
2213                 return $errors;
2214         }
2215
2216         /**
2217          * Check permissions on special pages & namespaces
2218          *
2219          * @param string $action The action to check
2220          * @param User $user User to check
2221          * @param array $errors List of current errors
2222          * @param string $rigor Same format as Title::getUserPermissionsErrors()
2223          * @param bool $short Short circuit on first error
2224          *
2225          * @return array List of errors
2226          */
2227         private function checkSpecialsAndNSPermissions( $action, $user, $errors, $rigor, $short ) {
2228                 # Only 'createaccount' can be performed on special pages,
2229                 # which don't actually exist in the DB.
2230                 if ( $this->isSpecialPage() && $action !== 'createaccount' ) {
2231                         $errors[] = [ 'ns-specialprotected' ];
2232                 }
2233
2234                 # Check $wgNamespaceProtection for restricted namespaces
2235                 if ( $this->isNamespaceProtected( $user ) ) {
2236                         $ns = $this->mNamespace == NS_MAIN ?
2237                                 wfMessage( 'nstab-main' )->text() : $this->getNsText();
2238                         $errors[] = $this->mNamespace == NS_MEDIAWIKI ?
2239                                 [ 'protectedinterface', $action ] : [ 'namespaceprotected', $ns, $action ];
2240                 }
2241
2242                 return $errors;
2243         }
2244
2245         /**
2246          * Check CSS/JS sub-page permissions
2247          *
2248          * @param string $action The action to check
2249          * @param User $user User to check
2250          * @param array $errors List of current errors
2251          * @param string $rigor Same format as Title::getUserPermissionsErrors()
2252          * @param bool $short Short circuit on first error
2253          *
2254          * @return array List of errors
2255          */
2256         private function checkCSSandJSPermissions( $action, $user, $errors, $rigor, $short ) {
2257                 # Protect css/js subpages of user pages
2258                 # XXX: this might be better using restrictions
2259                 if ( $action != 'patrol' ) {
2260                         if ( preg_match( '/^' . preg_quote( $user->getName(), '/' ) . '\//', $this->mTextform ) ) {
2261                                 if ( $this->isCssSubpage() && !$user->isAllowedAny( 'editmyusercss', 'editusercss' ) ) {
2262                                         $errors[] = [ 'mycustomcssprotected', $action ];
2263                                 } elseif ( $this->isJsSubpage() && !$user->isAllowedAny( 'editmyuserjs', 'edituserjs' ) ) {
2264                                         $errors[] = [ 'mycustomjsprotected', $action ];
2265                                 }
2266                         } else {
2267                                 if ( $this->isCssSubpage() && !$user->isAllowed( 'editusercss' ) ) {
2268                                         $errors[] = [ 'customcssprotected', $action ];
2269                                 } elseif ( $this->isJsSubpage() && !$user->isAllowed( 'edituserjs' ) ) {
2270                                         $errors[] = [ 'customjsprotected', $action ];
2271                                 }
2272                         }
2273                 }
2274
2275                 return $errors;
2276         }
2277
2278         /**
2279          * Check against page_restrictions table requirements on this
2280          * page. The user must possess all required rights for this
2281          * action.
2282          *
2283          * @param string $action The action to check
2284          * @param User $user User to check
2285          * @param array $errors List of current errors
2286          * @param string $rigor Same format as Title::getUserPermissionsErrors()
2287          * @param bool $short Short circuit on first error
2288          *
2289          * @return array List of errors
2290          */
2291         private function checkPageRestrictions( $action, $user, $errors, $rigor, $short ) {
2292                 foreach ( $this->getRestrictions( $action ) as $right ) {
2293                         // Backwards compatibility, rewrite sysop -> editprotected
2294                         if ( $right == 'sysop' ) {
2295                                 $right = 'editprotected';
2296                         }
2297                         // Backwards compatibility, rewrite autoconfirmed -> editsemiprotected
2298                         if ( $right == 'autoconfirmed' ) {
2299                                 $right = 'editsemiprotected';
2300                         }
2301                         if ( $right == '' ) {
2302                                 continue;
2303                         }
2304                         if ( !$user->isAllowed( $right ) ) {
2305                                 $errors[] = [ 'protectedpagetext', $right, $action ];
2306                         } elseif ( $this->mCascadeRestriction && !$user->isAllowed( 'protect' ) ) {
2307                                 $errors[] = [ 'protectedpagetext', 'protect', $action ];
2308                         }
2309                 }
2310
2311                 return $errors;
2312         }
2313
2314         /**
2315          * Check restrictions on cascading pages.
2316          *
2317          * @param string $action The action to check
2318          * @param User $user User to check
2319          * @param array $errors List of current errors
2320          * @param string $rigor Same format as Title::getUserPermissionsErrors()
2321          * @param bool $short Short circuit on first error
2322          *
2323          * @return array List of errors
2324          */
2325         private function checkCascadingSourcesRestrictions( $action, $user, $errors, $rigor, $short ) {
2326                 if ( $rigor !== 'quick' && !$this->isCssJsSubpage() ) {
2327                         # We /could/ use the protection level on the source page, but it's
2328                         # fairly ugly as we have to establish a precedence hierarchy for pages
2329                         # included by multiple cascade-protected pages. So just restrict
2330                         # it to people with 'protect' permission, as they could remove the
2331                         # protection anyway.
2332                         list( $cascadingSources, $restrictions ) = $this->getCascadeProtectionSources();
2333                         # Cascading protection depends on more than this page...
2334                         # Several cascading protected pages may include this page...
2335                         # Check each cascading level
2336                         # This is only for protection restrictions, not for all actions
2337                         if ( isset( $restrictions[$action] ) ) {
2338                                 foreach ( $restrictions[$action] as $right ) {
2339                                         // Backwards compatibility, rewrite sysop -> editprotected
2340                                         if ( $right == 'sysop' ) {
2341                                                 $right = 'editprotected';
2342                                         }
2343                                         // Backwards compatibility, rewrite autoconfirmed -> editsemiprotected
2344                                         if ( $right == 'autoconfirmed' ) {
2345                                                 $right = 'editsemiprotected';
2346                                         }
2347                                         if ( $right != '' && !$user->isAllowedAll( 'protect', $right ) ) {
2348                                                 $pages = '';
2349                                                 foreach ( $cascadingSources as $page ) {
2350                                                         $pages .= '* [[:' . $page->getPrefixedText() . "]]\n";
2351                                                 }
2352                                                 $errors[] = [ 'cascadeprotected', count( $cascadingSources ), $pages, $action ];
2353                                         }
2354                                 }
2355                         }
2356                 }
2357
2358                 return $errors;
2359         }
2360
2361         /**
2362          * Check action permissions not already checked in checkQuickPermissions
2363          *
2364          * @param string $action The action to check
2365          * @param User $user User to check
2366          * @param array $errors List of current errors
2367          * @param string $rigor Same format as Title::getUserPermissionsErrors()
2368          * @param bool $short Short circuit on first error
2369          *
2370          * @return array List of errors
2371          */
2372         private function checkActionPermissions( $action, $user, $errors, $rigor, $short ) {
2373                 global $wgDeleteRevisionsLimit, $wgLang;
2374
2375                 if ( $action == 'protect' ) {
2376                         if ( count( $this->getUserPermissionsErrorsInternal( 'edit', $user, $rigor, true ) ) ) {
2377                                 // If they can't edit, they shouldn't protect.
2378                                 $errors[] = [ 'protect-cantedit' ];
2379                         }
2380                 } elseif ( $action == 'create' ) {
2381                         $title_protection = $this->getTitleProtection();
2382                         if ( $title_protection ) {
2383                                 if ( $title_protection['permission'] == ''
2384                                         || !$user->isAllowed( $title_protection['permission'] )
2385                                 ) {
2386                                         $errors[] = [
2387                                                 'titleprotected',
2388                                                 User::whoIs( $title_protection['user'] ),
2389                                                 $title_protection['reason']
2390                                         ];
2391                                 }
2392                         }
2393                 } elseif ( $action == 'move' ) {
2394                         // Check for immobile pages
2395                         if ( !MWNamespace::isMovable( $this->mNamespace ) ) {
2396                                 // Specific message for this case
2397                                 $errors[] = [ 'immobile-source-namespace', $this->getNsText() ];
2398                         } elseif ( !$this->isMovable() ) {
2399                                 // Less specific message for rarer cases
2400                                 $errors[] = [ 'immobile-source-page' ];
2401                         }
2402                 } elseif ( $action == 'move-target' ) {
2403                         if ( !MWNamespace::isMovable( $this->mNamespace ) ) {
2404                                 $errors[] = [ 'immobile-target-namespace', $this->getNsText() ];
2405                         } elseif ( !$this->isMovable() ) {
2406                                 $errors[] = [ 'immobile-target-page' ];
2407                         }
2408                 } elseif ( $action == 'delete' ) {
2409                         $tempErrors = $this->checkPageRestrictions( 'edit', $user, [], $rigor, true );
2410                         if ( !$tempErrors ) {
2411                                 $tempErrors = $this->checkCascadingSourcesRestrictions( 'edit',
2412                                         $user, $tempErrors, $rigor, true );
2413                         }
2414                         if ( $tempErrors ) {
2415                                 // If protection keeps them from editing, they shouldn't be able to delete.
2416                                 $errors[] = [ 'deleteprotected' ];
2417                         }
2418                         if ( $rigor !== 'quick' && $wgDeleteRevisionsLimit
2419                                 && !$this->userCan( 'bigdelete', $user ) && $this->isBigDeletion()
2420                         ) {
2421                                 $errors[] = [ 'delete-toobig', $wgLang->formatNum( $wgDeleteRevisionsLimit ) ];
2422                         }
2423                 } elseif ( $action === 'undelete' ) {
2424                         if ( count( $this->getUserPermissionsErrorsInternal( 'edit', $user, $rigor, true ) ) ) {
2425                                 // Undeleting implies editing
2426                                 $errors[] = [ 'undelete-cantedit' ];
2427                         }
2428                         if ( !$this->exists()
2429                                 && count( $this->getUserPermissionsErrorsInternal( 'create', $user, $rigor, true ) )
2430                         ) {
2431                                 // Undeleting where nothing currently exists implies creating
2432                                 $errors[] = [ 'undelete-cantcreate' ];
2433                         }
2434                 }
2435                 return $errors;
2436         }
2437
2438         /**
2439          * Check that the user isn't blocked from editing.
2440          *
2441          * @param string $action The action to check
2442          * @param User $user User to check
2443          * @param array $errors List of current errors
2444          * @param string $rigor Same format as Title::getUserPermissionsErrors()
2445          * @param bool $short Short circuit on first error
2446          *
2447          * @return array List of errors
2448          */
2449         private function checkUserBlock( $action, $user, $errors, $rigor, $short ) {
2450                 global $wgEmailConfirmToEdit, $wgBlockDisablesLogin;
2451                 // Account creation blocks handled at userlogin.
2452                 // Unblocking handled in SpecialUnblock
2453                 if ( $rigor === 'quick' || in_array( $action, [ 'createaccount', 'unblock' ] ) ) {
2454                         return $errors;
2455                 }
2456
2457                 // Optimize for a very common case
2458                 if ( $action === 'read' && !$wgBlockDisablesLogin ) {
2459                         return $errors;
2460                 }
2461
2462                 if ( $wgEmailConfirmToEdit && !$user->isEmailConfirmed() ) {
2463                         $errors[] = [ 'confirmedittext' ];
2464                 }
2465
2466                 $useSlave = ( $rigor !== 'secure' );
2467                 if ( ( $action == 'edit' || $action == 'create' )
2468                         && !$user->isBlockedFrom( $this, $useSlave )
2469                 ) {
2470                         // Don't block the user from editing their own talk page unless they've been
2471                         // explicitly blocked from that too.
2472                 } elseif ( $user->isBlocked() && $user->getBlock()->prevents( $action ) !== false ) {
2473                         // @todo FIXME: Pass the relevant context into this function.
2474                         $errors[] = $user->getBlock()->getPermissionsError( RequestContext::getMain() );
2475                 }
2476
2477                 return $errors;
2478         }
2479
2480         /**
2481          * Check that the user is allowed to read this page.
2482          *
2483          * @param string $action The action to check
2484          * @param User $user User to check
2485          * @param array $errors List of current errors
2486          * @param string $rigor Same format as Title::getUserPermissionsErrors()
2487          * @param bool $short Short circuit on first error
2488          *
2489          * @return array List of errors
2490          */
2491         private function checkReadPermissions( $action, $user, $errors, $rigor, $short ) {
2492                 global $wgWhitelistRead, $wgWhitelistReadRegexp;
2493
2494                 $whitelisted = false;
2495                 if ( User::isEveryoneAllowed( 'read' ) ) {
2496                         # Shortcut for public wikis, allows skipping quite a bit of code
2497                         $whitelisted = true;
2498                 } elseif ( $user->isAllowed( 'read' ) ) {
2499                         # If the user is allowed to read pages, he is allowed to read all pages
2500                         $whitelisted = true;
2501                 } elseif ( $this->isSpecial( 'Userlogin' )
2502                         || $this->isSpecial( 'PasswordReset' )
2503                         || $this->isSpecial( 'Userlogout' )
2504                 ) {
2505                         # Always grant access to the login page.
2506                         # Even anons need to be able to log in.
2507                         $whitelisted = true;
2508                 } elseif ( is_array( $wgWhitelistRead ) && count( $wgWhitelistRead ) ) {
2509                         # Time to check the whitelist
2510                         # Only do these checks is there's something to check against
2511                         $name = $this->getPrefixedText();
2512                         $dbName = $this->getPrefixedDBkey();
2513
2514                         // Check for explicit whitelisting with and without underscores
2515                         if ( in_array( $name, $wgWhitelistRead, true ) || in_array( $dbName, $wgWhitelistRead, true ) ) {
2516                                 $whitelisted = true;
2517                         } elseif ( $this->getNamespace() == NS_MAIN ) {
2518                                 # Old settings might have the title prefixed with
2519                                 # a colon for main-namespace pages
2520                                 if ( in_array( ':' . $name, $wgWhitelistRead ) ) {
2521                                         $whitelisted = true;
2522                                 }
2523                         } elseif ( $this->isSpecialPage() ) {
2524                                 # If it's a special page, ditch the subpage bit and check again
2525                                 $name = $this->getDBkey();
2526                                 list( $name, /* $subpage */ ) = SpecialPageFactory::resolveAlias( $name );
2527                                 if ( $name ) {
2528                                         $pure = SpecialPage::getTitleFor( $name )->getPrefixedText();
2529                                         if ( in_array( $pure, $wgWhitelistRead, true ) ) {
2530                                                 $whitelisted = true;
2531                                         }
2532                                 }
2533                         }
2534                 }
2535
2536                 if ( !$whitelisted && is_array( $wgWhitelistReadRegexp ) && !empty( $wgWhitelistReadRegexp ) ) {
2537                         $name = $this->getPrefixedText();
2538                         // Check for regex whitelisting
2539                         foreach ( $wgWhitelistReadRegexp as $listItem ) {
2540                                 if ( preg_match( $listItem, $name ) ) {
2541                                         $whitelisted = true;
2542                                         break;
2543                                 }
2544                         }
2545                 }
2546
2547                 if ( !$whitelisted ) {
2548                         # If the title is not whitelisted, give extensions a chance to do so...
2549                         Hooks::run( 'TitleReadWhitelist', [ $this, $user, &$whitelisted ] );
2550                         if ( !$whitelisted ) {
2551                                 $errors[] = $this->missingPermissionError( $action, $short );
2552                         }
2553                 }
2554
2555                 return $errors;
2556         }
2557
2558         /**
2559          * Get a description array when the user doesn't have the right to perform
2560          * $action (i.e. when User::isAllowed() returns false)
2561          *
2562          * @param string $action The action to check
2563          * @param bool $short Short circuit on first error
2564          * @return array Array containing an error message key and any parameters
2565          */
2566         private function missingPermissionError( $action, $short ) {
2567                 // We avoid expensive display logic for quickUserCan's and such
2568                 if ( $short ) {
2569                         return [ 'badaccess-group0' ];
2570                 }
2571
2572                 return User::newFatalPermissionDeniedStatus( $action )->getErrorsArray()[0];
2573         }
2574
2575         /**
2576          * Can $user perform $action on this page? This is an internal function,
2577          * with multiple levels of checks depending on performance needs; see $rigor below.
2578          * It does not check wfReadOnly().
2579          *
2580          * @param string $action Action that permission needs to be checked for
2581          * @param User $user User to check
2582          * @param string $rigor One of (quick,full,secure)
2583          *   - quick  : does cheap permission checks from replica DBs (usable for GUI creation)
2584          *   - full   : does cheap and expensive checks possibly from a replica DB
2585          *   - secure : does cheap and expensive checks, using the master as needed
2586          * @param bool $short Set this to true to stop after the first permission error.
2587          * @return array Array of arrays of the arguments to wfMessage to explain permissions problems.
2588          */
2589         protected function getUserPermissionsErrorsInternal(
2590                 $action, $user, $rigor = 'secure', $short = false
2591         ) {
2592                 if ( $rigor === true ) {
2593                         $rigor = 'secure'; // b/c
2594                 } elseif ( $rigor === false ) {
2595                         $rigor = 'quick'; // b/c
2596                 } elseif ( !in_array( $rigor, [ 'quick', 'full', 'secure' ] ) ) {
2597                         throw new Exception( "Invalid rigor parameter '$rigor'." );
2598                 }
2599
2600                 # Read has special handling
2601                 if ( $action == 'read' ) {
2602                         $checks = [
2603                                 'checkPermissionHooks',
2604                                 'checkReadPermissions',
2605                                 'checkUserBlock', // for wgBlockDisablesLogin
2606                         ];
2607                 # Don't call checkSpecialsAndNSPermissions or checkCSSandJSPermissions
2608                 # here as it will lead to duplicate error messages. This is okay to do
2609                 # since anywhere that checks for create will also check for edit, and
2610                 # those checks are called for edit.
2611                 } elseif ( $action == 'create' ) {
2612                         $checks = [
2613                                 'checkQuickPermissions',
2614                                 'checkPermissionHooks',
2615                                 'checkPageRestrictions',
2616                                 'checkCascadingSourcesRestrictions',
2617                                 'checkActionPermissions',
2618                                 'checkUserBlock'
2619                         ];
2620                 } else {
2621                         $checks = [
2622                                 'checkQuickPermissions',
2623                                 'checkPermissionHooks',
2624                                 'checkSpecialsAndNSPermissions',
2625                                 'checkCSSandJSPermissions',
2626                                 'checkPageRestrictions',
2627                                 'checkCascadingSourcesRestrictions',
2628                                 'checkActionPermissions',
2629                                 'checkUserBlock'
2630                         ];
2631                 }
2632
2633                 $errors = [];
2634                 while ( count( $checks ) > 0 &&
2635                                 !( $short && count( $errors ) > 0 ) ) {
2636                         $method = array_shift( $checks );
2637                         $errors = $this->$method( $action, $user, $errors, $rigor, $short );
2638                 }
2639
2640                 return $errors;
2641         }
2642
2643         /**
2644          * Get a filtered list of all restriction types supported by this wiki.
2645          * @param bool $exists True to get all restriction types that apply to
2646          * titles that do exist, False for all restriction types that apply to
2647          * titles that do not exist
2648          * @return array
2649          */
2650         public static function getFilteredRestrictionTypes( $exists = true ) {
2651                 global $wgRestrictionTypes;
2652                 $types = $wgRestrictionTypes;
2653                 if ( $exists ) {
2654                         # Remove the create restriction for existing titles
2655                         $types = array_diff( $types, [ 'create' ] );
2656                 } else {
2657                         # Only the create and upload restrictions apply to non-existing titles
2658                         $types = array_intersect( $types, [ 'create', 'upload' ] );
2659                 }
2660                 return $types;
2661         }
2662
2663         /**
2664          * Returns restriction types for the current Title
2665          *
2666          * @return array Applicable restriction types
2667          */
2668         public function getRestrictionTypes() {
2669                 if ( $this->isSpecialPage() ) {
2670                         return [];
2671                 }
2672
2673                 $types = self::getFilteredRestrictionTypes( $this->exists() );
2674
2675                 if ( $this->getNamespace() != NS_FILE ) {
2676                         # Remove the upload restriction for non-file titles
2677                         $types = array_diff( $types, [ 'upload' ] );
2678                 }
2679
2680                 Hooks::run( 'TitleGetRestrictionTypes', [ $this, &$types ] );
2681
2682                 wfDebug( __METHOD__ . ': applicable restrictions to [[' .
2683                         $this->getPrefixedText() . ']] are {' . implode( ',', $types ) . "}\n" );
2684
2685                 return $types;
2686         }
2687
2688         /**
2689          * Is this title subject to title protection?
2690          * Title protection is the one applied against creation of such title.
2691          *
2692          * @return array|bool An associative array representing any existent title
2693          *   protection, or false if there's none.
2694          */
2695         public function getTitleProtection() {
2696                 $protection = $this->getTitleProtectionInternal();
2697                 if ( $protection ) {
2698                         if ( $protection['permission'] == 'sysop' ) {
2699                                 $protection['permission'] = 'editprotected'; // B/C
2700                         }
2701                         if ( $protection['permission'] == 'autoconfirmed' ) {
2702                                 $protection['permission'] = 'editsemiprotected'; // B/C
2703                         }
2704                 }
2705                 return $protection;
2706         }
2707
2708         /**
2709          * Fetch title protection settings
2710          *
2711          * To work correctly, $this->loadRestrictions() needs to have access to the
2712          * actual protections in the database without munging 'sysop' =>
2713          * 'editprotected' and 'autoconfirmed' => 'editsemiprotected'. Other
2714          * callers probably want $this->getTitleProtection() instead.
2715          *
2716          * @return array|bool
2717          */
2718         protected function getTitleProtectionInternal() {
2719                 // Can't protect pages in special namespaces
2720                 if ( $this->getNamespace() < 0 ) {
2721                         return false;
2722                 }
2723
2724                 // Can't protect pages that exist.
2725                 if ( $this->exists() ) {
2726                         return false;
2727                 }
2728
2729                 if ( $this->mTitleProtection === null ) {
2730                         $dbr = wfGetDB( DB_REPLICA );
2731                         $commentStore = new CommentStore( 'pt_reason' );
2732                         $commentQuery = $commentStore->getJoin();
2733                         $res = $dbr->select(
2734                                 [ 'protected_titles' ] + $commentQuery['tables'],
2735                                 [
2736                                         'user' => 'pt_user',
2737                                         'expiry' => 'pt_expiry',
2738                                         'permission' => 'pt_create_perm'
2739                                 ] + $commentQuery['fields'],
2740                                 [ 'pt_namespace' => $this->getNamespace(), 'pt_title' => $this->getDBkey() ],
2741                                 __METHOD__,
2742                                 [],
2743                                 $commentQuery['joins']
2744                         );
2745
2746                         // fetchRow returns false if there are no rows.
2747                         $row = $dbr->fetchRow( $res );
2748                         if ( $row ) {
2749                                 $this->mTitleProtection = [
2750                                         'user' => $row['user'],
2751                                         'expiry' => $dbr->decodeExpiry( $row['expiry'] ),
2752                                         'permission' => $row['permission'],
2753                                         'reason' => $commentStore->getComment( $row )->text,
2754                                 ];
2755                         } else {
2756                                 $this->mTitleProtection = false;
2757                         }
2758                 }
2759                 return $this->mTitleProtection;
2760         }
2761
2762         /**
2763          * Remove any title protection due to page existing
2764          */
2765         public function deleteTitleProtection() {
2766                 $dbw = wfGetDB( DB_MASTER );
2767
2768                 $dbw->delete(
2769                         'protected_titles',
2770                         [ 'pt_namespace' => $this->getNamespace(), 'pt_title' => $this->getDBkey() ],
2771                         __METHOD__
2772                 );
2773                 $this->mTitleProtection = false;
2774         }
2775
2776         /**
2777          * Is this page "semi-protected" - the *only* protection levels are listed
2778          * in $wgSemiprotectedRestrictionLevels?
2779          *
2780          * @param string $action Action to check (default: edit)
2781          * @return bool
2782          */
2783         public function isSemiProtected( $action = 'edit' ) {
2784                 global $wgSemiprotectedRestrictionLevels;
2785
2786                 $restrictions = $this->getRestrictions( $action );
2787                 $semi = $wgSemiprotectedRestrictionLevels;
2788                 if ( !$restrictions || !$semi ) {
2789                         // Not protected, or all protection is full protection
2790                         return false;
2791                 }
2792
2793                 // Remap autoconfirmed to editsemiprotected for BC
2794                 foreach ( array_keys( $semi, 'autoconfirmed' ) as $key ) {
2795                         $semi[$key] = 'editsemiprotected';
2796                 }
2797                 foreach ( array_keys( $restrictions, 'autoconfirmed' ) as $key ) {
2798                         $restrictions[$key] = 'editsemiprotected';
2799                 }
2800
2801                 return !array_diff( $restrictions, $semi );
2802         }
2803
2804         /**
2805          * Does the title correspond to a protected article?
2806          *
2807          * @param string $action The action the page is protected from,
2808          * by default checks all actions.
2809          * @return bool
2810          */
2811         public function isProtected( $action = '' ) {
2812                 global $wgRestrictionLevels;
2813
2814                 $restrictionTypes = $this->getRestrictionTypes();
2815
2816                 # Special pages have inherent protection
2817                 if ( $this->isSpecialPage() ) {
2818                         return true;
2819                 }
2820
2821                 # Check regular protection levels
2822                 foreach ( $restrictionTypes as $type ) {
2823                         if ( $action == $type || $action == '' ) {
2824                                 $r = $this->getRestrictions( $type );
2825                                 foreach ( $wgRestrictionLevels as $level ) {
2826                                         if ( in_array( $level, $r ) && $level != '' ) {
2827                                                 return true;
2828                                         }
2829                                 }
2830                         }
2831                 }
2832
2833                 return false;
2834         }
2835
2836         /**
2837          * Determines if $user is unable to edit this page because it has been protected
2838          * by $wgNamespaceProtection.
2839          *
2840          * @param User $user User object to check permissions
2841          * @return bool
2842          */
2843         public function isNamespaceProtected( User $user ) {
2844                 global $wgNamespaceProtection;
2845
2846                 if ( isset( $wgNamespaceProtection[$this->mNamespace] ) ) {
2847                         foreach ( (array)$wgNamespaceProtection[$this->mNamespace] as $right ) {
2848                                 if ( $right != '' && !$user->isAllowed( $right ) ) {
2849                                         return true;
2850                                 }
2851                         }
2852                 }
2853                 return false;
2854         }
2855
2856         /**
2857          * Cascading protection: Return true if cascading restrictions apply to this page, false if not.
2858          *
2859          * @return bool If the page is subject to cascading restrictions.
2860          */
2861         public function isCascadeProtected() {
2862                 list( $sources, /* $restrictions */ ) = $this->getCascadeProtectionSources( false );
2863                 return ( $sources > 0 );
2864         }
2865
2866         /**
2867          * Determines whether cascading protection sources have already been loaded from
2868          * the database.
2869          *
2870          * @param bool $getPages True to check if the pages are loaded, or false to check
2871          * if the status is loaded.
2872          * @return bool Whether or not the specified information has been loaded
2873          * @since 1.23
2874          */
2875         public function areCascadeProtectionSourcesLoaded( $getPages = true ) {
2876                 return $getPages ? $this->mCascadeSources !== null : $this->mHasCascadingRestrictions !== null;
2877         }
2878
2879         /**
2880          * Cascading protection: Get the source of any cascading restrictions on this page.
2881          *
2882          * @param bool $getPages Whether or not to retrieve the actual pages
2883          *        that the restrictions have come from and the actual restrictions
2884          *        themselves.
2885          * @return array Two elements: First is an array of Title objects of the
2886          *        pages from which cascading restrictions have come, false for
2887          *        none, or true if such restrictions exist but $getPages was not
2888          *        set. Second is an array like that returned by
2889          *        Title::getAllRestrictions(), or an empty array if $getPages is
2890          *        false.
2891          */
2892         public function getCascadeProtectionSources( $getPages = true ) {
2893                 $pagerestrictions = [];
2894
2895                 if ( $this->mCascadeSources !== null && $getPages ) {
2896                         return [ $this->mCascadeSources, $this->mCascadingRestrictions ];
2897                 } elseif ( $this->mHasCascadingRestrictions !== null && !$getPages ) {
2898                         return [ $this->mHasCascadingRestrictions, $pagerestrictions ];
2899                 }
2900
2901                 $dbr = wfGetDB( DB_REPLICA );
2902
2903                 if ( $this->getNamespace() == NS_FILE ) {
2904                         $tables = [ 'imagelinks', 'page_restrictions' ];
2905                         $where_clauses = [
2906                                 'il_to' => $this->getDBkey(),
2907                                 'il_from=pr_page',
2908                                 'pr_cascade' => 1
2909                         ];
2910                 } else {
2911                         $tables = [ 'templatelinks', 'page_restrictions' ];
2912                         $where_clauses = [
2913                                 'tl_namespace' => $this->getNamespace(),
2914                                 'tl_title' => $this->getDBkey(),
2915                                 'tl_from=pr_page',
2916                                 'pr_cascade' => 1
2917                         ];
2918                 }
2919
2920                 if ( $getPages ) {
2921                         $cols = [ 'pr_page', 'page_namespace', 'page_title',
2922                                 'pr_expiry', 'pr_type', 'pr_level' ];
2923                         $where_clauses[] = 'page_id=pr_page';
2924                         $tables[] = 'page';
2925                 } else {
2926                         $cols = [ 'pr_expiry' ];
2927                 }
2928
2929                 $res = $dbr->select( $tables, $cols, $where_clauses, __METHOD__ );
2930
2931                 $sources = $getPages ? [] : false;
2932                 $now = wfTimestampNow();
2933
2934                 foreach ( $res as $row ) {
2935                         $expiry = $dbr->decodeExpiry( $row->pr_expiry );
2936                         if ( $expiry > $now ) {
2937                                 if ( $getPages ) {
2938                                         $page_id = $row->pr_page;
2939                                         $page_ns = $row->page_namespace;
2940                                         $page_title = $row->page_title;
2941                                         $sources[$page_id] = self::makeTitle( $page_ns, $page_title );
2942                                         # Add groups needed for each restriction type if its not already there
2943                                         # Make sure this restriction type still exists
2944
2945                                         if ( !isset( $pagerestrictions[$row->pr_type] ) ) {
2946                                                 $pagerestrictions[$row->pr_type] = [];
2947                                         }
2948
2949                                         if (
2950                                                 isset( $pagerestrictions[$row->pr_type] )
2951                                                 && !in_array( $row->pr_level, $pagerestrictions[$row->pr_type] )
2952                                         ) {
2953                                                 $pagerestrictions[$row->pr_type][] = $row->pr_level;
2954                                         }
2955                                 } else {
2956                                         $sources = true;
2957                                 }
2958                         }
2959                 }
2960
2961                 if ( $getPages ) {
2962                         $this->mCascadeSources = $sources;
2963                         $this->mCascadingRestrictions = $pagerestrictions;
2964                 } else {
2965                         $this->mHasCascadingRestrictions = $sources;
2966                 }
2967
2968                 return [ $sources, $pagerestrictions ];
2969         }
2970
2971         /**
2972          * Accessor for mRestrictionsLoaded
2973          *
2974          * @return bool Whether or not the page's restrictions have already been
2975          * loaded from the database
2976          * @since 1.23
2977          */
2978         public function areRestrictionsLoaded() {
2979                 return $this->mRestrictionsLoaded;
2980         }
2981
2982         /**
2983          * Accessor/initialisation for mRestrictions
2984          *
2985          * @param string $action Action that permission needs to be checked for
2986          * @return array Restriction levels needed to take the action. All levels are
2987          *     required. Note that restriction levels are normally user rights, but 'sysop'
2988          *     and 'autoconfirmed' are also allowed for backwards compatibility. These should
2989          *     be mapped to 'editprotected' and 'editsemiprotected' respectively.
2990          */
2991         public function getRestrictions( $action ) {
2992                 if ( !$this->mRestrictionsLoaded ) {
2993                         $this->loadRestrictions();
2994                 }
2995                 return isset( $this->mRestrictions[$action] )
2996                                 ? $this->mRestrictions[$action]
2997                                 : [];
2998         }
2999
3000         /**
3001          * Accessor/initialisation for mRestrictions
3002          *
3003          * @return array Keys are actions, values are arrays as returned by
3004          *     Title::getRestrictions()
3005          * @since 1.23
3006          */
3007         public function getAllRestrictions() {
3008                 if ( !$this->mRestrictionsLoaded ) {
3009                         $this->loadRestrictions();
3010                 }
3011                 return $this->mRestrictions;
3012         }
3013
3014         /**
3015          * Get the expiry time for the restriction against a given action
3016          *
3017          * @param string $action
3018          * @return string|bool 14-char timestamp, or 'infinity' if the page is protected forever
3019          *     or not protected at all, or false if the action is not recognised.
3020          */
3021         public function getRestrictionExpiry( $action ) {
3022                 if ( !$this->mRestrictionsLoaded ) {
3023                         $this->loadRestrictions();
3024                 }
3025                 return isset( $this->mRestrictionsExpiry[$action] ) ? $this->mRestrictionsExpiry[$action] : false;
3026         }
3027
3028         /**
3029          * Returns cascading restrictions for the current article
3030          *
3031          * @return bool
3032          */
3033         function areRestrictionsCascading() {
3034                 if ( !$this->mRestrictionsLoaded ) {
3035                         $this->loadRestrictions();
3036                 }
3037
3038                 return $this->mCascadeRestriction;
3039         }
3040
3041         /**
3042          * Compiles list of active page restrictions from both page table (pre 1.10)
3043          * and page_restrictions table for this existing page.
3044          * Public for usage by LiquidThreads.
3045          *
3046          * @param array $rows Array of db result objects
3047          * @param string $oldFashionedRestrictions Comma-separated list of page
3048          *   restrictions from page table (pre 1.10)
3049          */
3050         public function loadRestrictionsFromRows( $rows, $oldFashionedRestrictions = null ) {
3051                 $dbr = wfGetDB( DB_REPLICA );
3052
3053                 $restrictionTypes = $this->getRestrictionTypes();
3054
3055                 foreach ( $restrictionTypes as $type ) {
3056                         $this->mRestrictions[$type] = [];
3057                         $this->mRestrictionsExpiry[$type] = 'infinity';
3058                 }
3059
3060                 $this->mCascadeRestriction = false;
3061
3062                 # Backwards-compatibility: also load the restrictions from the page record (old format).
3063                 if ( $oldFashionedRestrictions !== null ) {
3064                         $this->mOldRestrictions = $oldFashionedRestrictions;
3065                 }
3066
3067                 if ( $this->mOldRestrictions === false ) {
3068                         $this->mOldRestrictions = $dbr->selectField( 'page', 'page_restrictions',
3069                                 [ 'page_id' => $this->getArticleID() ], __METHOD__ );
3070                 }
3071
3072                 if ( $this->mOldRestrictions != '' ) {
3073                         foreach ( explode( ':', trim( $this->mOldRestrictions ) ) as $restrict ) {
3074                                 $temp = explode( '=', trim( $restrict ) );
3075                                 if ( count( $temp ) == 1 ) {
3076                                         // old old format should be treated as edit/move restriction
3077                                         $this->mRestrictions['edit'] = explode( ',', trim( $temp[0] ) );
3078                                         $this->mRestrictions['move'] = explode( ',', trim( $temp[0] ) );
3079                                 } else {
3080                                         $restriction = trim( $temp[1] );
3081                                         if ( $restriction != '' ) { // some old entries are empty
3082                                                 $this->mRestrictions[$temp[0]] = explode( ',', $restriction );
3083                                         }
3084                                 }
3085                         }
3086                 }
3087
3088                 if ( count( $rows ) ) {
3089                         # Current system - load second to make them override.
3090                         $now = wfTimestampNow();
3091
3092                         # Cycle through all the restrictions.
3093                         foreach ( $rows as $row ) {
3094                                 // Don't take care of restrictions types that aren't allowed
3095                                 if ( !in_array( $row->pr_type, $restrictionTypes ) ) {
3096                                         continue;
3097                                 }
3098
3099                                 $expiry = $dbr->decodeExpiry( $row->pr_expiry );
3100
3101                                 // Only apply the restrictions if they haven't expired!
3102                                 if ( !$expiry || $expiry > $now ) {
3103                                         $this->mRestrictionsExpiry[$row->pr_type] = $expiry;
3104                                         $this->mRestrictions[$row->pr_type] = explode( ',', trim( $row->pr_level ) );
3105
3106                                         $this->mCascadeRestriction |= $row->pr_cascade;
3107                                 }
3108                         }
3109                 }
3110
3111                 $this->mRestrictionsLoaded = true;
3112         }
3113
3114         /**
3115          * Load restrictions from the page_restrictions table
3116          *
3117          * @param string $oldFashionedRestrictions Comma-separated list of page
3118          *   restrictions from page table (pre 1.10)
3119          */
3120         public function loadRestrictions( $oldFashionedRestrictions = null ) {
3121                 if ( $this->mRestrictionsLoaded ) {
3122                         return;
3123                 }
3124
3125                 $id = $this->getArticleID();
3126                 if ( $id ) {
3127                         $cache = ObjectCache::getMainWANInstance();
3128                         $rows = $cache->getWithSetCallback(
3129                                 // Page protections always leave a new null revision
3130                                 $cache->makeKey( 'page-restrictions', $id, $this->getLatestRevID() ),
3131                                 $cache::TTL_DAY,
3132                                 function ( $curValue, &$ttl, array &$setOpts ) {
3133                                         $dbr = wfGetDB( DB_REPLICA );
3134
3135                                         $setOpts += Database::getCacheSetOptions( $dbr );
3136
3137                                         return iterator_to_array(
3138                                                 $dbr->select(
3139                                                         'page_restrictions',
3140                                                         [ 'pr_type', 'pr_expiry', 'pr_level', 'pr_cascade' ],
3141                                                         [ 'pr_page' => $this->getArticleID() ],
3142                                                         __METHOD__
3143                                                 )
3144                                         );
3145                                 }
3146                         );
3147
3148                         $this->loadRestrictionsFromRows( $rows, $oldFashionedRestrictions );
3149                 } else {
3150                         $title_protection = $this->getTitleProtectionInternal();
3151
3152                         if ( $title_protection ) {
3153                                 $now = wfTimestampNow();
3154                                 $expiry = wfGetDB( DB_REPLICA )->decodeExpiry( $title_protection['expiry'] );
3155
3156                                 if ( !$expiry || $expiry > $now ) {
3157                                         // Apply the restrictions
3158                                         $this->mRestrictionsExpiry['create'] = $expiry;
3159                                         $this->mRestrictions['create'] =
3160                                                 explode( ',', trim( $title_protection['permission'] ) );
3161                                 } else { // Get rid of the old restrictions
3162                                         $this->mTitleProtection = false;
3163                                 }
3164                         } else {
3165                                 $this->mRestrictionsExpiry['create'] = 'infinity';
3166                         }
3167                         $this->mRestrictionsLoaded = true;
3168                 }
3169         }
3170
3171         /**
3172          * Flush the protection cache in this object and force reload from the database.
3173          * This is used when updating protection from WikiPage::doUpdateRestrictions().
3174          */
3175         public function flushRestrictions() {
3176                 $this->mRestrictionsLoaded = false;
3177                 $this->mTitleProtection = null;
3178         }
3179
3180         /**
3181          * Purge expired restrictions from the page_restrictions table
3182          *
3183          * This will purge no more than $wgUpdateRowsPerQuery page_restrictions rows
3184          */
3185         static function purgeExpiredRestrictions() {
3186                 if ( wfReadOnly() ) {
3187                         return;
3188                 }
3189
3190                 DeferredUpdates::addUpdate( new AtomicSectionUpdate(
3191                         wfGetDB( DB_MASTER ),
3192                         __METHOD__,
3193                         function ( IDatabase $dbw, $fname ) {
3194                                 $config = MediaWikiServices::getInstance()->getMainConfig();
3195                                 $ids = $dbw->selectFieldValues(
3196                                         'page_restrictions',
3197                                         'pr_id',
3198                                         [ 'pr_expiry < ' . $dbw->addQuotes( $dbw->timestamp() ) ],
3199                                         $fname,
3200                                         [ 'LIMIT' => $config->get( 'UpdateRowsPerQuery' ) ] // T135470
3201                                 );
3202                                 if ( $ids ) {
3203                                         $dbw->delete( 'page_restrictions', [ 'pr_id' => $ids ], $fname );
3204                                 }
3205                         }
3206                 ) );
3207
3208                 DeferredUpdates::addUpdate( new AtomicSectionUpdate(
3209                         wfGetDB( DB_MASTER ),
3210                         __METHOD__,
3211                         function ( IDatabase $dbw, $fname ) {
3212                                 $dbw->delete(
3213                                         'protected_titles',
3214                                         [ 'pt_expiry < ' . $dbw->addQuotes( $dbw->timestamp() ) ],
3215                                         $fname
3216                                 );
3217                         }
3218                 ) );
3219         }
3220
3221         /**
3222          * Does this have subpages?  (Warning, usually requires an extra DB query.)
3223          *
3224          * @return bool
3225          */
3226         public function hasSubpages() {
3227                 if ( !MWNamespace::hasSubpages( $this->mNamespace ) ) {
3228                         # Duh
3229                         return false;
3230                 }
3231
3232                 # We dynamically add a member variable for the purpose of this method
3233                 # alone to cache the result.  There's no point in having it hanging
3234                 # around uninitialized in every Title object; therefore we only add it
3235                 # if needed and don't declare it statically.
3236                 if ( $this->mHasSubpages === null ) {
3237                         $this->mHasSubpages = false;
3238                         $subpages = $this->getSubpages( 1 );
3239                         if ( $subpages instanceof TitleArray ) {
3240                                 $this->mHasSubpages = (bool)$subpages->count();
3241                         }
3242                 }
3243
3244                 return $this->mHasSubpages;
3245         }
3246
3247         /**
3248          * Get all subpages of this page.
3249          *
3250          * @param int $limit Maximum number of subpages to fetch; -1 for no limit
3251          * @return TitleArray|array TitleArray, or empty array if this page's namespace
3252          *  doesn't allow subpages
3253          */
3254         public function getSubpages( $limit = -1 ) {
3255                 if ( !MWNamespace::hasSubpages( $this->getNamespace() ) ) {
3256                         return [];
3257                 }
3258
3259                 $dbr = wfGetDB( DB_REPLICA );
3260                 $conds['page_namespace'] = $this->getNamespace();
3261                 $conds[] = 'page_title ' . $dbr->buildLike( $this->getDBkey() . '/', $dbr->anyString() );
3262                 $options = [];
3263                 if ( $limit > -1 ) {
3264                         $options['LIMIT'] = $limit;
3265                 }
3266                 return TitleArray::newFromResult(
3267                         $dbr->select( 'page',
3268                                 [ 'page_id', 'page_namespace', 'page_title', 'page_is_redirect' ],
3269                                 $conds,
3270                                 __METHOD__,
3271                                 $options
3272                         )
3273                 );
3274         }
3275
3276         /**
3277          * Is there a version of this page in the deletion archive?
3278          *
3279          * @return int The number of archived revisions
3280          */
3281         public function isDeleted() {
3282                 if ( $this->getNamespace() < 0 ) {
3283                         $n = 0;
3284                 } else {
3285                         $dbr = wfGetDB( DB_REPLICA );
3286
3287                         $n = $dbr->selectField( 'archive', 'COUNT(*)',
3288                                 [ 'ar_namespace' => $this->getNamespace(), 'ar_title' => $this->getDBkey() ],
3289                                 __METHOD__
3290                         );
3291                         if ( $this->getNamespace() == NS_FILE ) {
3292                                 $n += $dbr->selectField( 'filearchive', 'COUNT(*)',
3293                                         [ 'fa_name' => $this->getDBkey() ],
3294                                         __METHOD__
3295                                 );
3296                         }
3297                 }
3298                 return (int)$n;
3299         }
3300
3301         /**
3302          * Is there a version of this page in the deletion archive?
3303          *
3304          * @return bool
3305          */
3306         public function isDeletedQuick() {
3307                 if ( $this->getNamespace() < 0 ) {
3308                         return false;
3309                 }
3310                 $dbr = wfGetDB( DB_REPLICA );
3311                 $deleted = (bool)$dbr->selectField( 'archive', '1',
3312                         [ 'ar_namespace' => $this->getNamespace(), 'ar_title' => $this->getDBkey() ],
3313                         __METHOD__
3314                 );
3315                 if ( !$deleted && $this->getNamespace() == NS_FILE ) {
3316                         $deleted = (bool)$dbr->selectField( 'filearchive', '1',
3317                                 [ 'fa_name' => $this->getDBkey() ],
3318                                 __METHOD__
3319                         );
3320                 }
3321                 return $deleted;
3322         }
3323
3324         /**
3325          * Get the article ID for this Title from the link cache,
3326          * adding it if necessary
3327          *
3328          * @param int $flags A bit field; may be Title::GAID_FOR_UPDATE to select
3329          *  for update
3330          * @return int The ID
3331          */
3332         public function getArticleID( $flags = 0 ) {
3333                 if ( $this->getNamespace() < 0 ) {
3334                         $this->mArticleID = 0;
3335                         return $this->mArticleID;
3336                 }
3337                 $linkCache = LinkCache::singleton();
3338                 if ( $flags & self::GAID_FOR_UPDATE ) {
3339                         $oldUpdate = $linkCache->forUpdate( true );
3340                         $linkCache->clearLink( $this );
3341                         $this->mArticleID = $linkCache->addLinkObj( $this );
3342                         $linkCache->forUpdate( $oldUpdate );
3343                 } else {
3344                         if ( -1 == $this->mArticleID ) {
3345                                 $this->mArticleID = $linkCache->addLinkObj( $this );
3346                         }
3347                 }
3348                 return $this->mArticleID;
3349         }
3350
3351         /**
3352          * Is this an article that is a redirect page?
3353          * Uses link cache, adding it if necessary
3354          *
3355          * @param int $flags A bit field; may be Title::GAID_FOR_UPDATE to select for update
3356          * @return bool
3357          */
3358         public function isRedirect( $flags = 0 ) {
3359                 if ( !is_null( $this->mRedirect ) ) {
3360                         return $this->mRedirect;
3361                 }
3362                 if ( !$this->getArticleID( $flags ) ) {
3363                         $this->mRedirect = false;
3364                         return $this->mRedirect;
3365                 }
3366
3367                 $linkCache = LinkCache::singleton();
3368                 $linkCache->addLinkObj( $this ); # in case we already had an article ID
3369                 $cached = $linkCache->getGoodLinkFieldObj( $this, 'redirect' );
3370                 if ( $cached === null ) {
3371                         # Trust LinkCache's state over our own
3372                         # LinkCache is telling us that the page doesn't exist, despite there being cached
3373                         # data relating to an existing page in $this->mArticleID. Updaters should clear
3374                         # LinkCache as appropriate, or use $flags = Title::GAID_FOR_UPDATE. If that flag is
3375                         # set, then LinkCache will definitely be up to date here, since getArticleID() forces
3376                         # LinkCache to refresh its data from the master.
3377                         $this->mRedirect = false;
3378                         return $this->mRedirect;
3379                 }
3380
3381                 $this->mRedirect = (bool)$cached;
3382
3383                 return $this->mRedirect;
3384         }
3385
3386         /**
3387          * What is the length of this page?
3388          * Uses link cache, adding it if necessary
3389          *
3390          * @param int $flags A bit field; may be Title::GAID_FOR_UPDATE to select for update
3391          * @return int
3392          */
3393         public function getLength( $flags = 0 ) {
3394                 if ( $this->mLength != -1 ) {
3395                         return $this->mLength;
3396                 }
3397                 if ( !$this->getArticleID( $flags ) ) {
3398                         $this->mLength = 0;
3399                         return $this->mLength;
3400                 }
3401                 $linkCache = LinkCache::singleton();
3402                 $linkCache->addLinkObj( $this ); # in case we already had an article ID
3403                 $cached = $linkCache->getGoodLinkFieldObj( $this, 'length' );
3404                 if ( $cached === null ) {
3405                         # Trust LinkCache's state over our own, as for isRedirect()
3406                         $this->mLength = 0;
3407                         return $this->mLength;
3408                 }
3409
3410                 $this->mLength = intval( $cached );
3411
3412                 return $this->mLength;
3413         }
3414
3415         /**
3416          * What is the page_latest field for this page?
3417          *
3418          * @param int $flags A bit field; may be Title::GAID_FOR_UPDATE to select for update
3419          * @return int Int or 0 if the page doesn't exist
3420          */
3421         public function getLatestRevID( $flags = 0 ) {
3422                 if ( !( $flags & self::GAID_FOR_UPDATE ) && $this->mLatestID !== false ) {
3423                         return intval( $this->mLatestID );
3424                 }
3425                 if ( !$this->getArticleID( $flags ) ) {
3426                         $this->mLatestID = 0;
3427                         return $this->mLatestID;
3428                 }
3429                 $linkCache = LinkCache::singleton();
3430                 $linkCache->addLinkObj( $this ); # in case we already had an article ID
3431                 $cached = $linkCache->getGoodLinkFieldObj( $this, 'revision' );
3432                 if ( $cached === null ) {
3433                         # Trust LinkCache's state over our own, as for isRedirect()
3434                         $this->mLatestID = 0;
3435                         return $this->mLatestID;
3436                 }
3437
3438                 $this->mLatestID = intval( $cached );
3439
3440                 return $this->mLatestID;
3441         }
3442
3443         /**
3444          * This clears some fields in this object, and clears any associated
3445          * keys in the "bad links" section of the link cache.
3446          *
3447          * - This is called from WikiPage::doEditContent() and WikiPage::insertOn() to allow
3448          * loading of the new page_id. It's also called from
3449          * WikiPage::doDeleteArticleReal()
3450          *
3451          * @param int $newid The new Article ID
3452          */
3453         public function resetArticleID( $newid ) {
3454                 $linkCache = LinkCache::singleton();
3455                 $linkCache->clearLink( $this );
3456
3457                 if ( $newid === false ) {
3458                         $this->mArticleID = -1;
3459                 } else {
3460                         $this->mArticleID = intval( $newid );
3461                 }
3462                 $this->mRestrictionsLoaded = false;
3463                 $this->mRestrictions = [];
3464                 $this->mOldRestrictions = false;
3465                 $this->mRedirect = null;
3466                 $this->mLength = -1;
3467                 $this->mLatestID = false;
3468                 $this->mContentModel = false;
3469                 $this->mEstimateRevisions = null;
3470                 $this->mPageLanguage = false;
3471                 $this->mDbPageLanguage = false;
3472                 $this->mIsBigDeletion = null;
3473         }
3474
3475         public static function clearCaches() {
3476                 $linkCache = LinkCache::singleton();
3477                 $linkCache->clear();
3478
3479                 $titleCache = self::getTitleCache();
3480                 $titleCache->clear();
3481         }
3482
3483         /**
3484          * Capitalize a text string for a title if it belongs to a namespace that capitalizes
3485          *
3486          * @param string $text Containing title to capitalize
3487          * @param int $ns Namespace index, defaults to NS_MAIN
3488          * @return string Containing capitalized title
3489          */
3490         public static function capitalize( $text, $ns = NS_MAIN ) {
3491                 global $wgContLang;
3492
3493                 if ( MWNamespace::isCapitalized( $ns ) ) {
3494                         return $wgContLang->ucfirst( $text );
3495                 } else {
3496                         return $text;
3497                 }
3498         }
3499
3500         /**
3501          * Secure and split - main initialisation function for this object
3502          *
3503          * Assumes that mDbkeyform has been set, and is urldecoded
3504          * and uses underscores, but not otherwise munged.  This function
3505          * removes illegal characters, splits off the interwiki and
3506          * namespace prefixes, sets the other forms, and canonicalizes
3507          * everything.
3508          *
3509          * @throws MalformedTitleException On invalid titles
3510          * @return bool True on success
3511          */
3512         private function secureAndSplit() {
3513                 # Initialisation
3514                 $this->mInterwiki = '';
3515                 $this->mFragment = '';
3516                 $this->mNamespace = $this->mDefaultNamespace; # Usually NS_MAIN
3517
3518                 $dbkey = $this->mDbkeyform;
3519
3520                 // @note: splitTitleString() is a temporary hack to allow MediaWikiTitleCodec to share
3521                 //        the parsing code with Title, while avoiding massive refactoring.
3522                 // @todo: get rid of secureAndSplit, refactor parsing code.
3523                 // @note: getTitleParser() returns a TitleParser implementation which does not have a
3524                 //        splitTitleString method, but the only implementation (MediaWikiTitleCodec) does
3525                 $titleCodec = MediaWikiServices::getInstance()->getTitleParser();
3526                 // MalformedTitleException can be thrown here
3527                 $parts = $titleCodec->splitTitleString( $dbkey, $this->getDefaultNamespace() );
3528
3529                 # Fill fields
3530                 $this->setFragment( '#' . $parts['fragment'] );
3531                 $this->mInterwiki = $parts['interwiki'];
3532                 $this->mLocalInterwiki = $parts['local_interwiki'];
3533                 $this->mNamespace = $parts['namespace'];
3534                 $this->mUserCaseDBKey = $parts['user_case_dbkey'];
3535
3536                 $this->mDbkeyform = $parts['dbkey'];
3537                 $this->mUrlform = wfUrlencode( $this->mDbkeyform );
3538                 $this->mTextform = strtr( $this->mDbkeyform, '_', ' ' );
3539
3540                 # We already know that some pages won't be in the database!
3541                 if ( $this->isExternal() || $this->isSpecialPage() ) {
3542                         $this->mArticleID = 0;
3543                 }
3544
3545                 return true;
3546         }
3547
3548         /**
3549          * Get an array of Title objects linking to this Title
3550          * Also stores the IDs in the link cache.
3551          *
3552          * WARNING: do not use this function on arbitrary user-supplied titles!
3553          * On heavily-used templates it will max out the memory.
3554          *
3555          * @param array $options May be FOR UPDATE
3556          * @param string $table Table name
3557          * @param string $prefix Fields prefix
3558          * @return Title[] Array of Title objects linking here
3559          */
3560         public function getLinksTo( $options = [], $table = 'pagelinks', $prefix = 'pl' ) {
3561                 if ( count( $options ) > 0 ) {
3562                         $db = wfGetDB( DB_MASTER );
3563                 } else {
3564                         $db = wfGetDB( DB_REPLICA );
3565                 }
3566
3567                 $res = $db->select(
3568                         [ 'page', $table ],
3569                         self::getSelectFields(),
3570                         [
3571                                 "{$prefix}_from=page_id",
3572                                 "{$prefix}_namespace" => $this->getNamespace(),
3573                                 "{$prefix}_title" => $this->getDBkey() ],
3574                         __METHOD__,
3575                         $options
3576                 );
3577
3578                 $retVal = [];
3579                 if ( $res->numRows() ) {
3580                         $linkCache = LinkCache::singleton();
3581                         foreach ( $res as $row ) {
3582                                 $titleObj = self::makeTitle( $row->page_namespace, $row->page_title );
3583                                 if ( $titleObj ) {
3584                                         $linkCache->addGoodLinkObjFromRow( $titleObj, $row );
3585                                         $retVal[] = $titleObj;
3586                                 }
3587                         }
3588                 }
3589                 return $retVal;
3590         }
3591
3592         /**
3593          * Get an array of Title objects using this Title as a template
3594          * Also stores the IDs in the link cache.
3595          *
3596          * WARNING: do not use this function on arbitrary user-supplied titles!
3597          * On heavily-used templates it will max out the memory.
3598          *
3599          * @param array $options Query option to Database::select()
3600          * @return Title[] Array of Title the Title objects linking here
3601          */
3602         public function getTemplateLinksTo( $options = [] ) {
3603                 return $this->getLinksTo( $options, 'templatelinks', 'tl' );
3604         }
3605
3606         /**
3607          * Get an array of Title objects linked from this Title
3608          * Also stores the IDs in the link cache.
3609          *
3610          * WARNING: do not use this function on arbitrary user-supplied titles!
3611          * On heavily-used templates it will max out the memory.
3612          *
3613          * @param array $options Query option to Database::select()
3614          * @param string $table Table name
3615          * @param string $prefix Fields prefix
3616          * @return array Array of Title objects linking here
3617          */
3618         public function getLinksFrom( $options = [], $table = 'pagelinks', $prefix = 'pl' ) {
3619                 $id = $this->getArticleID();
3620
3621                 # If the page doesn't exist; there can't be any link from this page
3622                 if ( !$id ) {
3623                         return [];
3624                 }
3625
3626                 $db = wfGetDB( DB_REPLICA );
3627
3628                 $blNamespace = "{$prefix}_namespace";
3629                 $blTitle = "{$prefix}_title";
3630
3631                 $res = $db->select(
3632                         [ $table, 'page' ],
3633                         array_merge(
3634                                 [ $blNamespace, $blTitle ],
3635                                 WikiPage::selectFields()
3636                         ),
3637                         [ "{$prefix}_from" => $id ],
3638                         __METHOD__,
3639                         $options,
3640                         [ 'page' => [
3641                                 'LEFT JOIN',
3642                                 [ "page_namespace=$blNamespace", "page_title=$blTitle" ]
3643                         ] ]
3644                 );
3645
3646                 $retVal = [];
3647                 $linkCache = LinkCache::singleton();
3648                 foreach ( $res as $row ) {
3649                         if ( $row->page_id ) {
3650                                 $titleObj = self::newFromRow( $row );
3651                         } else {
3652                                 $titleObj = self::makeTitle( $row->$blNamespace, $row->$blTitle );
3653                                 $linkCache->addBadLinkObj( $titleObj );
3654                         }
3655                         $retVal[] = $titleObj;
3656                 }
3657
3658                 return $retVal;
3659         }
3660
3661         /**
3662          * Get an array of Title objects used on this Title as a template
3663          * Also stores the IDs in the link cache.
3664          *
3665          * WARNING: do not use this function on arbitrary user-supplied titles!
3666          * On heavily-used templates it will max out the memory.
3667          *
3668          * @param array $options May be FOR UPDATE
3669          * @return Title[] Array of Title the Title objects used here
3670          */
3671         public function getTemplateLinksFrom( $options = [] ) {
3672                 return $this->getLinksFrom( $options, 'templatelinks', 'tl' );
3673         }
3674
3675         /**
3676          * Get an array of Title objects referring to non-existent articles linked
3677          * from this page.
3678          *
3679          * @todo check if needed (used only in SpecialBrokenRedirects.php, and
3680          *   should use redirect table in this case).
3681          * @return Title[] Array of Title the Title objects
3682          */
3683         public function getBrokenLinksFrom() {
3684                 if ( $this->getArticleID() == 0 ) {
3685                         # All links from article ID 0 are false positives
3686                         return [];
3687                 }
3688
3689                 $dbr = wfGetDB( DB_REPLICA );
3690                 $res = $dbr->select(
3691                         [ 'page', 'pagelinks' ],
3692                         [ 'pl_namespace', 'pl_title' ],
3693                         [
3694                                 'pl_from' => $this->getArticleID(),
3695                                 'page_namespace IS NULL'
3696                         ],
3697                         __METHOD__, [],
3698                         [
3699                                 'page' => [
3700                                         'LEFT JOIN',
3701                                         [ 'pl_namespace=page_namespace', 'pl_title=page_title' ]
3702                                 ]
3703                         ]
3704                 );
3705
3706                 $retVal = [];
3707                 foreach ( $res as $row ) {
3708                         $retVal[] = self::makeTitle( $row->pl_namespace, $row->pl_title );
3709                 }
3710                 return $retVal;
3711         }
3712
3713         /**
3714          * Get a list of URLs to purge from the CDN cache when this
3715          * page changes
3716          *
3717          * @return string[] Array of String the URLs
3718          */
3719         public function getCdnUrls() {
3720                 $urls = [
3721                         $this->getInternalURL(),
3722                         $this->getInternalURL( 'action=history' )
3723                 ];
3724
3725                 $pageLang = $this->getPageLanguage();
3726                 if ( $pageLang->hasVariants() ) {
3727                         $variants = $pageLang->getVariants();
3728                         foreach ( $variants as $vCode ) {
3729                                 $urls[] = $this->getInternalURL( $vCode );
3730                         }
3731                 }
3732
3733                 // If we are looking at a css/js user subpage, purge the action=raw.
3734                 if ( $this->isJsSubpage() ) {
3735                         $urls[] = $this->getInternalURL( 'action=raw&ctype=text/javascript' );
3736                 } elseif ( $this->isCssSubpage() ) {
3737                         $urls[] = $this->getInternalURL( 'action=raw&ctype=text/css' );
3738                 }
3739
3740                 Hooks::run( 'TitleSquidURLs', [ $this, &$urls ] );
3741                 return $urls;
3742         }
3743
3744         /**
3745          * @deprecated since 1.27 use getCdnUrls()
3746          */
3747         public function getSquidURLs() {
3748                 return $this->getCdnUrls();
3749         }
3750
3751         /**
3752          * Purge all applicable CDN URLs
3753          */
3754         public function purgeSquid() {
3755                 DeferredUpdates::addUpdate(
3756                         new CdnCacheUpdate( $this->getCdnUrls() ),
3757                         DeferredUpdates::PRESEND
3758                 );
3759         }
3760
3761         /**
3762          * Check whether a given move operation would be valid.
3763          * Returns true if ok, or a getUserPermissionsErrors()-like array otherwise
3764          *
3765          * @deprecated since 1.25, use MovePage's methods instead
3766          * @param Title &$nt The new title
3767          * @param bool $auth Whether to check user permissions (uses $wgUser)
3768          * @param string $reason Is the log summary of the move, used for spam checking
3769          * @return array|bool True on success, getUserPermissionsErrors()-like array on failure
3770          */
3771         public function isValidMoveOperation( &$nt, $auth = true, $reason = '' ) {
3772                 global $wgUser;
3773
3774                 if ( !( $nt instanceof Title ) ) {
3775                         // Normally we'd add this to $errors, but we'll get
3776                         // lots of syntax errors if $nt is not an object
3777                         return [ [ 'badtitletext' ] ];
3778                 }
3779
3780                 $mp = new MovePage( $this, $nt );
3781                 $errors = $mp->isValidMove()->getErrorsArray();
3782                 if ( $auth ) {
3783                         $errors = wfMergeErrorArrays(
3784                                 $errors,
3785                                 $mp->checkPermissions( $wgUser, $reason )->getErrorsArray()
3786                         );
3787                 }
3788
3789                 return $errors ?: true;
3790         }
3791
3792         /**
3793          * Check if the requested move target is a valid file move target
3794          * @todo move this to MovePage
3795          * @param Title $nt Target title
3796          * @return array List of errors
3797          */
3798         protected function validateFileMoveOperation( $nt ) {
3799                 global $wgUser;
3800
3801                 $errors = [];
3802
3803                 $destFile = wfLocalFile( $nt );
3804                 $destFile->load( File::READ_LATEST );
3805                 if ( !$wgUser->isAllowed( 'reupload-shared' )
3806                         && !$destFile->exists() && wfFindFile( $nt )
3807                 ) {
3808                         $errors[] = [ 'file-exists-sharedrepo' ];
3809                 }
3810
3811                 return $errors;
3812         }
3813
3814         /**
3815          * Move a title to a new location
3816          *
3817          * @deprecated since 1.25, use the MovePage class instead
3818          * @param Title &$nt The new title
3819          * @param bool $auth Indicates whether $wgUser's permissions
3820          *  should be checked
3821          * @param string $reason The reason for the move
3822          * @param bool $createRedirect Whether to create a redirect from the old title to the new title.
3823          *  Ignored if the user doesn't have the suppressredirect right.
3824          * @param array $changeTags Applied to the entry in the move log and redirect page revision
3825          * @return array|bool True on success, getUserPermissionsErrors()-like array on failure
3826          */
3827         public function moveTo( &$nt, $auth = true, $reason = '', $createRedirect = true,
3828                 array $changeTags = []
3829         ) {
3830                 global $wgUser;
3831                 $err = $this->isValidMoveOperation( $nt, $auth, $reason );
3832                 if ( is_array( $err ) ) {
3833                         // Auto-block user's IP if the account was "hard" blocked
3834                         $wgUser->spreadAnyEditBlock();
3835                         return $err;
3836                 }
3837                 // Check suppressredirect permission
3838                 if ( $auth && !$wgUser->isAllowed( 'suppressredirect' ) ) {
3839                         $createRedirect = true;
3840                 }
3841
3842                 $mp = new MovePage( $this, $nt );
3843                 $status = $mp->move( $wgUser, $reason, $createRedirect, $changeTags );
3844                 if ( $status->isOK() ) {
3845                         return true;
3846                 } else {
3847                         return $status->getErrorsArray();
3848                 }
3849         }
3850
3851         /**
3852          * Move this page's subpages to be subpages of $nt
3853          *
3854          * @param Title $nt Move target
3855          * @param bool $auth Whether $wgUser's permissions should be checked
3856          * @param string $reason The reason for the move
3857          * @param bool $createRedirect Whether to create redirects from the old subpages to
3858          *     the new ones Ignored if the user doesn't have the 'suppressredirect' right
3859          * @param array $changeTags Applied to the entry in the move log and redirect page revision
3860          * @return array Array with old page titles as keys, and strings (new page titles) or
3861          *     getUserPermissionsErrors()-like arrays (errors) as values, or a
3862          *     getUserPermissionsErrors()-like error array with numeric indices if
3863          *     no pages were moved
3864          */
3865         public function moveSubpages( $nt, $auth = true, $reason = '', $createRedirect = true,
3866                 array $changeTags = []
3867         ) {
3868                 global $wgMaximumMovedPages;
3869                 // Check permissions
3870                 if ( !$this->userCan( 'move-subpages' ) ) {
3871                         return [
3872                                 [ 'cant-move-subpages' ],
3873                         ];
3874                 }
3875                 // Do the source and target namespaces support subpages?
3876                 if ( !MWNamespace::hasSubpages( $this->getNamespace() ) ) {
3877                         return [
3878                                 [ 'namespace-nosubpages', MWNamespace::getCanonicalName( $this->getNamespace() ) ],
3879                         ];
3880                 }
3881                 if ( !MWNamespace::hasSubpages( $nt->getNamespace() ) ) {
3882                         return [
3883                                 [ 'namespace-nosubpages', MWNamespace::getCanonicalName( $nt->getNamespace() ) ],
3884                         ];
3885                 }
3886
3887                 $subpages = $this->getSubpages( $wgMaximumMovedPages + 1 );
3888                 $retval = [];
3889                 $count = 0;
3890                 foreach ( $subpages as $oldSubpage ) {
3891                         $count++;
3892                         if ( $count > $wgMaximumMovedPages ) {
3893                                 $retval[$oldSubpage->getPrefixedText()] = [
3894                                         [ 'movepage-max-pages', $wgMaximumMovedPages ],
3895                                 ];
3896                                 break;
3897                         }
3898
3899                         // We don't know whether this function was called before
3900                         // or after moving the root page, so check both
3901                         // $this and $nt
3902                         if ( $oldSubpage->getArticleID() == $this->getArticleID()
3903                                 || $oldSubpage->getArticleID() == $nt->getArticleID()
3904                         ) {
3905                                 // When moving a page to a subpage of itself,
3906                                 // don't move it twice
3907                                 continue;
3908                         }
3909                         $newPageName = preg_replace(
3910                                         '#^' . preg_quote( $this->getDBkey(), '#' ) . '#',
3911                                         StringUtils::escapeRegexReplacement( $nt->getDBkey() ), # T23234
3912                                         $oldSubpage->getDBkey() );
3913                         if ( $oldSubpage->isTalkPage() ) {
3914                                 $newNs = $nt->getTalkPage()->getNamespace();
3915                         } else {
3916                                 $newNs = $nt->getSubjectPage()->getNamespace();
3917                         }
3918                         # T16385: we need makeTitleSafe because the new page names may
3919                         # be longer than 255 characters.
3920                         $newSubpage = self::makeTitleSafe( $newNs, $newPageName );
3921
3922                         $success = $oldSubpage->moveTo( $newSubpage, $auth, $reason, $createRedirect, $changeTags );
3923                         if ( $success === true ) {
3924                                 $retval[$oldSubpage->getPrefixedText()] = $newSubpage->getPrefixedText();
3925                         } else {
3926                                 $retval[$oldSubpage->getPrefixedText()] = $success;
3927                         }
3928                 }
3929                 return $retval;
3930         }
3931
3932         /**
3933          * Checks if this page is just a one-rev redirect.
3934          * Adds lock, so don't use just for light purposes.
3935          *
3936          * @return bool
3937          */
3938         public function isSingleRevRedirect() {
3939                 global $wgContentHandlerUseDB;
3940
3941                 $dbw = wfGetDB( DB_MASTER );
3942
3943                 # Is it a redirect?
3944                 $fields = [ 'page_is_redirect', 'page_latest', 'page_id' ];
3945                 if ( $wgContentHandlerUseDB ) {
3946                         $fields[] = 'page_content_model';
3947                 }
3948
3949                 $row = $dbw->selectRow( 'page',
3950                         $fields,
3951                         $this->pageCond(),
3952                         __METHOD__,
3953                         [ 'FOR UPDATE' ]
3954                 );
3955                 # Cache some fields we may want
3956                 $this->mArticleID = $row ? intval( $row->page_id ) : 0;
3957                 $this->mRedirect = $row ? (bool)$row->page_is_redirect : false;
3958                 $this->mLatestID = $row ? intval( $row->page_latest ) : false;
3959                 $this->mContentModel = $row && isset( $row->page_content_model )
3960                         ? strval( $row->page_content_model )
3961                         : false;
3962
3963                 if ( !$this->mRedirect ) {
3964                         return false;
3965                 }
3966                 # Does the article have a history?
3967                 $row = $dbw->selectField( [ 'page', 'revision' ],
3968                         'rev_id',
3969                         [ 'page_namespace' => $this->getNamespace(),
3970                                 'page_title' => $this->getDBkey(),
3971                                 'page_id=rev_page',
3972                                 'page_latest != rev_id'
3973                         ],
3974                         __METHOD__,
3975                         [ 'FOR UPDATE' ]
3976                 );
3977                 # Return true if there was no history
3978                 return ( $row === false );
3979         }
3980
3981         /**
3982          * Checks if $this can be moved to a given Title
3983          * - Selects for update, so don't call it unless you mean business
3984          *
3985          * @deprecated since 1.25, use MovePage's methods instead
3986          * @param Title $nt The new title to check
3987          * @return bool
3988          */
3989         public function isValidMoveTarget( $nt ) {
3990                 # Is it an existing file?
3991                 if ( $nt->getNamespace() == NS_FILE ) {
3992                         $file = wfLocalFile( $nt );
3993                         $file->load( File::READ_LATEST );
3994                         if ( $file->exists() ) {
3995                                 wfDebug( __METHOD__ . ": file exists\n" );
3996                                 return false;
3997                         }
3998                 }
3999                 # Is it a redirect with no history?
4000                 if ( !$nt->isSingleRevRedirect() ) {
4001                         wfDebug( __METHOD__ . ": not a one-rev redirect\n" );
4002                         return false;
4003                 }
4004                 # Get the article text
4005                 $rev = Revision::newFromTitle( $nt, false, Revision::READ_LATEST );
4006                 if ( !is_object( $rev ) ) {
4007                         return false;
4008                 }
4009                 $content = $rev->getContent();
4010                 # Does the redirect point to the source?
4011                 # Or is it a broken self-redirect, usually caused by namespace collisions?
4012                 $redirTitle = $content ? $content->getRedirectTarget() : null;
4013
4014                 if ( $redirTitle ) {
4015                         if ( $redirTitle->getPrefixedDBkey() != $this->getPrefixedDBkey() &&
4016                                 $redirTitle->getPrefixedDBkey() != $nt->getPrefixedDBkey() ) {
4017                                 wfDebug( __METHOD__ . ": redirect points to other page\n" );
4018                                 return false;
4019                         } else {
4020                                 return true;
4021                         }
4022                 } else {
4023                         # Fail safe (not a redirect after all. strange.)
4024                         wfDebug( __METHOD__ . ": failsafe: database sais " . $nt->getPrefixedDBkey() .
4025                                                 " is a redirect, but it doesn't contain a valid redirect.\n" );
4026                         return false;
4027                 }
4028         }
4029
4030         /**
4031          * Get categories to which this Title belongs and return an array of
4032          * categories' names.
4033          *
4034          * @return array Array of parents in the form:
4035          *     $parent => $currentarticle
4036          */
4037         public function getParentCategories() {
4038                 global $wgContLang;
4039
4040                 $data = [];
4041
4042                 $titleKey = $this->getArticleID();
4043
4044                 if ( $titleKey === 0 ) {
4045                         return $data;
4046                 }
4047
4048                 $dbr = wfGetDB( DB_REPLICA );
4049
4050                 $res = $dbr->select(
4051                         'categorylinks',
4052                         'cl_to',
4053                         [ 'cl_from' => $titleKey ],
4054                         __METHOD__
4055                 );
4056
4057                 if ( $res->numRows() > 0 ) {
4058                         foreach ( $res as $row ) {
4059                                 // $data[] = Title::newFromText($wgContLang->getNsText ( NS_CATEGORY ).':'.$row->cl_to);
4060                                 $data[$wgContLang->getNsText( NS_CATEGORY ) . ':' . $row->cl_to] = $this->getFullText();
4061                         }
4062                 }
4063                 return $data;
4064         }
4065
4066         /**
4067          * Get a tree of parent categories
4068          *
4069          * @param array $children Array with the children in the keys, to check for circular refs
4070          * @return array Tree of parent categories
4071          */
4072         public function getParentCategoryTree( $children = [] ) {
4073                 $stack = [];
4074                 $parents = $this->getParentCategories();
4075
4076                 if ( $parents ) {
4077                         foreach ( $parents as $parent => $current ) {
4078                                 if ( array_key_exists( $parent, $children ) ) {
4079                                         # Circular reference
4080                                         $stack[$parent] = [];
4081                                 } else {
4082                                         $nt = self::newFromText( $parent );
4083                                         if ( $nt ) {
4084                                                 $stack[$parent] = $nt->getParentCategoryTree( $children + [ $parent => 1 ] );
4085                                         }
4086                                 }
4087                         }
4088                 }
4089
4090                 return $stack;
4091         }
4092
4093         /**
4094          * Get an associative array for selecting this title from
4095          * the "page" table
4096          *
4097          * @return array Array suitable for the $where parameter of DB::select()
4098          */
4099         public function pageCond() {
4100                 if ( $this->mArticleID > 0 ) {
4101                         // PK avoids secondary lookups in InnoDB, shouldn't hurt other DBs
4102                         return [ 'page_id' => $this->mArticleID ];
4103                 } else {
4104                         return [ 'page_namespace' => $this->mNamespace, 'page_title' => $this->mDbkeyform ];
4105                 }
4106         }
4107
4108         /**
4109          * Get next/previous revision ID relative to another revision ID
4110          * @param int $revId Revision ID. Get the revision that was before this one.
4111          * @param int $flags Title::GAID_FOR_UPDATE
4112          * @param string $dir 'next' or 'prev'
4113          * @return int|bool New revision ID, or false if none exists
4114          */
4115         private function getRelativeRevisionID( $revId, $flags, $dir ) {
4116                 $revId = (int)$revId;
4117                 if ( $dir === 'next' ) {
4118                         $op = '>';
4119                         $sort = 'ASC';
4120                 } elseif ( $dir === 'prev' ) {
4121                         $op = '<';
4122                         $sort = 'DESC';
4123                 } else {
4124                         throw new InvalidArgumentException( '$dir must be "next" or "prev"' );
4125                 }
4126
4127                 if ( $flags & self::GAID_FOR_UPDATE ) {
4128                         $db = wfGetDB( DB_MASTER );
4129                 } else {
4130                         $db = wfGetDB( DB_REPLICA, 'contributions' );
4131                 }
4132
4133                 // Intentionally not caring if the specified revision belongs to this
4134                 // page. We only care about the timestamp.
4135                 $ts = $db->selectField( 'revision', 'rev_timestamp', [ 'rev_id' => $revId ], __METHOD__ );
4136                 if ( $ts === false ) {
4137                         $ts = $db->selectField( 'archive', 'ar_timestamp', [ 'ar_rev_id' => $revId ], __METHOD__ );
4138                         if ( $ts === false ) {
4139                                 // Or should this throw an InvalidArgumentException or something?
4140                                 return false;
4141                         }
4142                 }
4143                 $ts = $db->addQuotes( $ts );
4144
4145                 $revId = $db->selectField( 'revision', 'rev_id',
4146                         [
4147                                 'rev_page' => $this->getArticleID( $flags ),
4148                                 "rev_timestamp $op $ts OR (rev_timestamp = $ts AND rev_id $op $revId)"
4149                         ],
4150                         __METHOD__,
4151                         [
4152                                 'ORDER BY' => "rev_timestamp $sort, rev_id $sort",
4153                                 'IGNORE INDEX' => 'rev_timestamp', // Probably needed for T159319
4154                         ]
4155                 );
4156
4157                 if ( $revId === false ) {
4158                         return false;
4159                 } else {
4160                         return intval( $revId );
4161                 }
4162         }
4163
4164         /**
4165          * Get the revision ID of the previous revision
4166          *
4167          * @param int $revId Revision ID. Get the revision that was before this one.
4168          * @param int $flags Title::GAID_FOR_UPDATE
4169          * @return int|bool Old revision ID, or false if none exists
4170          */
4171         public function getPreviousRevisionID( $revId, $flags = 0 ) {
4172                 return $this->getRelativeRevisionID( $revId, $flags, 'prev' );
4173         }
4174
4175         /**
4176          * Get the revision ID of the next revision
4177          *
4178          * @param int $revId Revision ID. Get the revision that was after this one.
4179          * @param int $flags Title::GAID_FOR_UPDATE
4180          * @return int|bool Next revision ID, or false if none exists
4181          */
4182         public function getNextRevisionID( $revId, $flags = 0 ) {
4183                 return $this->getRelativeRevisionID( $revId, $flags, 'next' );
4184         }
4185
4186         /**
4187          * Get the first revision of the page
4188          *
4189          * @param int $flags Title::GAID_FOR_UPDATE
4190          * @return Revision|null If page doesn't exist
4191          */
4192         public function getFirstRevision( $flags = 0 ) {
4193                 $pageId = $this->getArticleID( $flags );
4194                 if ( $pageId ) {
4195                         $db = ( $flags & self::GAID_FOR_UPDATE ) ? wfGetDB( DB_MASTER ) : wfGetDB( DB_REPLICA );
4196                         $row = $db->selectRow( 'revision', Revision::selectFields(),
4197                                 [ 'rev_page' => $pageId ],
4198                                 __METHOD__,
4199                                 [
4200                                         'ORDER BY' => 'rev_timestamp ASC, rev_id ASC',
4201                                         'IGNORE INDEX' => 'rev_timestamp', // See T159319
4202                                 ]
4203                         );
4204                         if ( $row ) {
4205                                 return new Revision( $row );
4206                         }
4207                 }
4208                 return null;
4209         }
4210
4211         /**
4212          * Get the oldest revision timestamp of this page
4213          *
4214          * @param int $flags Title::GAID_FOR_UPDATE
4215          * @return string MW timestamp
4216          */
4217         public function getEarliestRevTime( $flags = 0 ) {
4218                 $rev = $this->getFirstRevision( $flags );
4219                 return $rev ? $rev->getTimestamp() : null;
4220         }
4221
4222         /**
4223          * Check if this is a new page
4224          *
4225          * @return bool
4226          */
4227         public function isNewPage() {
4228                 $dbr = wfGetDB( DB_REPLICA );
4229                 return (bool)$dbr->selectField( 'page', 'page_is_new', $this->pageCond(), __METHOD__ );
4230         }
4231
4232         /**
4233          * Check whether the number of revisions of this page surpasses $wgDeleteRevisionsLimit
4234          *
4235          * @return bool
4236          */
4237         public function isBigDeletion() {
4238                 global $wgDeleteRevisionsLimit;
4239
4240                 if ( !$wgDeleteRevisionsLimit ) {
4241                         return false;
4242                 }
4243
4244                 if ( $this->mIsBigDeletion === null ) {
4245                         $dbr = wfGetDB( DB_REPLICA );
4246
4247                         $revCount = $dbr->selectRowCount(
4248                                 'revision',
4249                                 '1',
4250                                 [ 'rev_page' => $this->getArticleID() ],
4251                                 __METHOD__,
4252                                 [ 'LIMIT' => $wgDeleteRevisionsLimit + 1 ]
4253                         );
4254
4255                         $this->mIsBigDeletion = $revCount > $wgDeleteRevisionsLimit;
4256                 }
4257
4258                 return $this->mIsBigDeletion;
4259         }
4260
4261         /**
4262          * Get the approximate revision count of this page.
4263          *
4264          * @return int
4265          */
4266         public function estimateRevisionCount() {
4267                 if ( !$this->exists() ) {
4268                         return 0;
4269                 }
4270
4271                 if ( $this->mEstimateRevisions === null ) {
4272                         $dbr = wfGetDB( DB_REPLICA );
4273                         $this->mEstimateRevisions = $dbr->estimateRowCount( 'revision', '*',
4274                                 [ 'rev_page' => $this->getArticleID() ], __METHOD__ );
4275                 }
4276
4277                 return $this->mEstimateRevisions;
4278         }
4279
4280         /**
4281          * Get the number of revisions between the given revision.
4282          * Used for diffs and other things that really need it.
4283          *
4284          * @param int|Revision $old Old revision or rev ID (first before range)
4285          * @param int|Revision $new New revision or rev ID (first after range)
4286          * @param int|null $max Limit of Revisions to count, will be incremented to detect truncations
4287          * @return int Number of revisions between these revisions.
4288          */
4289         public function countRevisionsBetween( $old, $new, $max = null ) {
4290                 if ( !( $old instanceof Revision ) ) {
4291                         $old = Revision::newFromTitle( $this, (int)$old );
4292                 }
4293                 if ( !( $new instanceof Revision ) ) {
4294                         $new = Revision::newFromTitle( $this, (int)$new );
4295                 }
4296                 if ( !$old || !$new ) {
4297                         return 0; // nothing to compare
4298                 }
4299                 $dbr = wfGetDB( DB_REPLICA );
4300                 $conds = [
4301                         'rev_page' => $this->getArticleID(),
4302                         'rev_timestamp > ' . $dbr->addQuotes( $dbr->timestamp( $old->getTimestamp() ) ),
4303                         'rev_timestamp < ' . $dbr->addQuotes( $dbr->timestamp( $new->getTimestamp() ) )
4304                 ];
4305                 if ( $max !== null ) {
4306                         return $dbr->selectRowCount( 'revision', '1',
4307                                 $conds,
4308                                 __METHOD__,
4309                                 [ 'LIMIT' => $max + 1 ] // extra to detect truncation
4310                         );
4311                 } else {
4312                         return (int)$dbr->selectField( 'revision', 'count(*)', $conds, __METHOD__ );
4313                 }
4314         }
4315
4316         /**
4317          * Get the authors between the given revisions or revision IDs.
4318          * Used for diffs and other things that really need it.
4319          *
4320          * @since 1.23
4321          *
4322          * @param int|Revision $old Old revision or rev ID (first before range by default)
4323          * @param int|Revision $new New revision or rev ID (first after range by default)
4324          * @param int $limit Maximum number of authors
4325          * @param string|array $options (Optional): Single option, or an array of options:
4326          *     'include_old' Include $old in the range; $new is excluded.
4327          *     'include_new' Include $new in the range; $old is excluded.
4328          *     'include_both' Include both $old and $new in the range.
4329          *     Unknown option values are ignored.
4330          * @return array|null Names of revision authors in the range; null if not both revisions exist
4331          */
4332         public function getAuthorsBetween( $old, $new, $limit, $options = [] ) {
4333                 if ( !( $old instanceof Revision ) ) {
4334                         $old = Revision::newFromTitle( $this, (int)$old );
4335                 }
4336                 if ( !( $new instanceof Revision ) ) {
4337                         $new = Revision::newFromTitle( $this, (int)$new );
4338                 }
4339                 // XXX: what if Revision objects are passed in, but they don't refer to this title?
4340                 // Add $old->getPage() != $new->getPage() || $old->getPage() != $this->getArticleID()
4341                 // in the sanity check below?
4342                 if ( !$old || !$new ) {
4343                         return null; // nothing to compare
4344                 }
4345                 $authors = [];
4346                 $old_cmp = '>';
4347                 $new_cmp = '<';
4348                 $options = (array)$options;
4349                 if ( in_array( 'include_old', $options ) ) {
4350                         $old_cmp = '>=';
4351                 }
4352                 if ( in_array( 'include_new', $options ) ) {
4353                         $new_cmp = '<=';
4354                 }
4355                 if ( in_array( 'include_both', $options ) ) {
4356                         $old_cmp = '>=';
4357                         $new_cmp = '<=';
4358                 }
4359                 // No DB query needed if $old and $new are the same or successive revisions:
4360                 if ( $old->getId() === $new->getId() ) {
4361                         return ( $old_cmp === '>' && $new_cmp === '<' ) ?
4362                                 [] :
4363                                 [ $old->getUserText( Revision::RAW ) ];
4364                 } elseif ( $old->getId() === $new->getParentId() ) {
4365                         if ( $old_cmp === '>=' && $new_cmp === '<=' ) {
4366                                 $authors[] = $old->getUserText( Revision::RAW );
4367                                 if ( $old->getUserText( Revision::RAW ) != $new->getUserText( Revision::RAW ) ) {
4368                                         $authors[] = $new->getUserText( Revision::RAW );
4369                                 }
4370                         } elseif ( $old_cmp === '>=' ) {
4371                                 $authors[] = $old->getUserText( Revision::RAW );
4372                         } elseif ( $new_cmp === '<=' ) {
4373                                 $authors[] = $new->getUserText( Revision::RAW );
4374                         }
4375                         return $authors;
4376                 }
4377                 $dbr = wfGetDB( DB_REPLICA );
4378                 $res = $dbr->select( 'revision', 'DISTINCT rev_user_text',
4379                         [
4380                                 'rev_page' => $this->getArticleID(),
4381                                 "rev_timestamp $old_cmp " . $dbr->addQuotes( $dbr->timestamp( $old->getTimestamp() ) ),
4382                                 "rev_timestamp $new_cmp " . $dbr->addQuotes( $dbr->timestamp( $new->getTimestamp() ) )
4383                         ], __METHOD__,
4384                         [ 'LIMIT' => $limit + 1 ] // add one so caller knows it was truncated
4385                 );
4386                 foreach ( $res as $row ) {
4387                         $authors[] = $row->rev_user_text;
4388                 }
4389                 return $authors;
4390         }
4391
4392         /**
4393          * Get the number of authors between the given revisions or revision IDs.
4394          * Used for diffs and other things that really need it.
4395          *
4396          * @param int|Revision $old Old revision or rev ID (first before range by default)
4397          * @param int|Revision $new New revision or rev ID (first after range by default)
4398          * @param int $limit Maximum number of authors
4399          * @param string|array $options (Optional): Single option, or an array of options:
4400          *     'include_old' Include $old in the range; $new is excluded.
4401          *     'include_new' Include $new in the range; $old is excluded.
4402          *     'include_both' Include both $old and $new in the range.
4403          *     Unknown option values are ignored.
4404          * @return int Number of revision authors in the range; zero if not both revisions exist
4405          */
4406         public function countAuthorsBetween( $old, $new, $limit, $options = [] ) {
4407                 $authors = $this->getAuthorsBetween( $old, $new, $limit, $options );
4408                 return $authors ? count( $authors ) : 0;
4409         }
4410
4411         /**
4412          * Compare with another title.
4413          *
4414          * @param Title $title
4415          * @return bool
4416          */
4417         public function equals( Title $title ) {
4418                 // Note: === is necessary for proper matching of number-like titles.
4419                 return $this->getInterwiki() === $title->getInterwiki()
4420                         && $this->getNamespace() == $title->getNamespace()
4421                         && $this->getDBkey() === $title->getDBkey();
4422         }
4423
4424         /**
4425          * Check if this title is a subpage of another title
4426          *
4427          * @param Title $title
4428          * @return bool
4429          */
4430         public function isSubpageOf( Title $title ) {
4431                 return $this->getInterwiki() === $title->getInterwiki()
4432                         && $this->getNamespace() == $title->getNamespace()
4433                         && strpos( $this->getDBkey(), $title->getDBkey() . '/' ) === 0;
4434         }
4435
4436         /**
4437          * Check if page exists.  For historical reasons, this function simply
4438          * checks for the existence of the title in the page table, and will
4439          * thus return false for interwiki links, special pages and the like.
4440          * If you want to know if a title can be meaningfully viewed, you should
4441          * probably call the isKnown() method instead.
4442          *
4443          * @param int $flags An optional bit field; may be Title::GAID_FOR_UPDATE to check
4444          *   from master/for update
4445          * @return bool
4446          */
4447         public function exists( $flags = 0 ) {
4448                 $exists = $this->getArticleID( $flags ) != 0;
4449                 Hooks::run( 'TitleExists', [ $this, &$exists ] );
4450                 return $exists;
4451         }
4452
4453         /**
4454          * Should links to this title be shown as potentially viewable (i.e. as
4455          * "bluelinks"), even if there's no record by this title in the page
4456          * table?
4457          *
4458          * This function is semi-deprecated for public use, as well as somewhat
4459          * misleadingly named.  You probably just want to call isKnown(), which
4460          * calls this function internally.
4461          *
4462          * (ISSUE: Most of these checks are cheap, but the file existence check
4463          * can potentially be quite expensive.  Including it here fixes a lot of
4464          * existing code, but we might want to add an optional parameter to skip
4465          * it and any other expensive checks.)
4466          *
4467          * @return bool
4468          */
4469         public function isAlwaysKnown() {
4470                 $isKnown = null;
4471
4472                 /**
4473                  * Allows overriding default behavior for determining if a page exists.
4474                  * If $isKnown is kept as null, regular checks happen. If it's
4475                  * a boolean, this value is returned by the isKnown method.
4476                  *
4477                  * @since 1.20
4478                  *
4479                  * @param Title $title
4480                  * @param bool|null $isKnown
4481                  */
4482                 Hooks::run( 'TitleIsAlwaysKnown', [ $this, &$isKnown ] );
4483
4484                 if ( !is_null( $isKnown ) ) {
4485                         return $isKnown;
4486                 }
4487
4488                 if ( $this->isExternal() ) {
4489                         return true;  // any interwiki link might be viewable, for all we know
4490                 }
4491
4492                 switch ( $this->mNamespace ) {
4493                         case NS_MEDIA:
4494                         case NS_FILE:
4495                                 // file exists, possibly in a foreign repo
4496                                 return (bool)wfFindFile( $this );
4497                         case NS_SPECIAL:
4498                                 // valid special page
4499                                 return SpecialPageFactory::exists( $this->getDBkey() );
4500                         case NS_MAIN:
4501                                 // selflink, possibly with fragment
4502                                 return $this->mDbkeyform == '';
4503                         case NS_MEDIAWIKI:
4504                                 // known system message
4505                                 return $this->hasSourceText() !== false;
4506                         default:
4507                                 return false;
4508                 }
4509         }
4510
4511         /**
4512          * Does this title refer to a page that can (or might) be meaningfully
4513          * viewed?  In particular, this function may be used to determine if
4514          * links to the title should be rendered as "bluelinks" (as opposed to
4515          * "redlinks" to non-existent pages).
4516          * Adding something else to this function will cause inconsistency
4517          * since LinkHolderArray calls isAlwaysKnown() and does its own
4518          * page existence check.
4519          *
4520          * @return bool
4521          */
4522         public function isKnown() {
4523                 return $this->isAlwaysKnown() || $this->exists();
4524         }
4525
4526         /**
4527          * Does this page have source text?
4528          *
4529          * @return bool
4530          */
4531         public function hasSourceText() {
4532                 if ( $this->exists() ) {
4533                         return true;
4534                 }
4535
4536                 if ( $this->mNamespace == NS_MEDIAWIKI ) {
4537                         // If the page doesn't exist but is a known system message, default
4538                         // message content will be displayed, same for language subpages-
4539                         // Use always content language to avoid loading hundreds of languages
4540                         // to get the link color.
4541                         global $wgContLang;
4542                         list( $name, ) = MessageCache::singleton()->figureMessage(
4543                                 $wgContLang->lcfirst( $this->getText() )
4544                         );
4545                         $message = wfMessage( $name )->inLanguage( $wgContLang )->useDatabase( false );
4546                         return $message->exists();
4547                 }
4548
4549                 return false;
4550         }
4551
4552         /**
4553          * Get the default message text or false if the message doesn't exist
4554          *
4555          * @return string|bool
4556          */
4557         public function getDefaultMessageText() {
4558                 global $wgContLang;
4559
4560                 if ( $this->getNamespace() != NS_MEDIAWIKI ) { // Just in case
4561                         return false;
4562                 }
4563
4564                 list( $name, $lang ) = MessageCache::singleton()->figureMessage(
4565                         $wgContLang->lcfirst( $this->getText() )
4566                 );
4567                 $message = wfMessage( $name )->inLanguage( $lang )->useDatabase( false );
4568
4569                 if ( $message->exists() ) {
4570                         return $message->plain();
4571                 } else {
4572                         return false;
4573                 }
4574         }
4575
4576         /**
4577          * Updates page_touched for this page; called from LinksUpdate.php
4578          *
4579          * @param string $purgeTime [optional] TS_MW timestamp
4580          * @return bool True if the update succeeded
4581          */
4582         public function invalidateCache( $purgeTime = null ) {
4583                 if ( wfReadOnly() ) {
4584                         return false;
4585                 } elseif ( $this->mArticleID === 0 ) {
4586                         return true; // avoid gap locking if we know it's not there
4587                 }
4588
4589                 $dbw = wfGetDB( DB_MASTER );
4590                 $dbw->onTransactionPreCommitOrIdle( function () {
4591                         ResourceLoaderWikiModule::invalidateModuleCache( $this, null, null, wfWikiID() );
4592                 } );
4593
4594                 $conds = $this->pageCond();
4595                 DeferredUpdates::addUpdate(
4596                         new AutoCommitUpdate(
4597                                 $dbw,
4598                                 __METHOD__,
4599                                 function ( IDatabase $dbw, $fname ) use ( $conds, $purgeTime ) {
4600                                         $dbTimestamp = $dbw->timestamp( $purgeTime ?: time() );
4601                                         $dbw->update(
4602                                                 'page',
4603                                                 [ 'page_touched' => $dbTimestamp ],
4604                                                 $conds + [ 'page_touched < ' . $dbw->addQuotes( $dbTimestamp ) ],
4605                                                 $fname
4606                                         );
4607                                         MediaWikiServices::getInstance()->getLinkCache()->invalidateTitle( $this );
4608                                 }
4609                         ),
4610                         DeferredUpdates::PRESEND
4611                 );
4612
4613                 return true;
4614         }
4615
4616         /**
4617          * Update page_touched timestamps and send CDN purge messages for
4618          * pages linking to this title. May be sent to the job queue depending
4619          * on the number of links. Typically called on create and delete.
4620          */
4621         public function touchLinks() {
4622                 DeferredUpdates::addUpdate( new HTMLCacheUpdate( $this, 'pagelinks' ) );
4623                 if ( $this->getNamespace() == NS_CATEGORY ) {
4624                         DeferredUpdates::addUpdate( new HTMLCacheUpdate( $this, 'categorylinks' ) );
4625                 }
4626         }
4627
4628         /**
4629          * Get the last touched timestamp
4630          *
4631          * @param IDatabase $db Optional db
4632          * @return string|false Last-touched timestamp
4633          */
4634         public function getTouched( $db = null ) {
4635                 if ( $db === null ) {
4636                         $db = wfGetDB( DB_REPLICA );
4637                 }
4638                 $touched = $db->selectField( 'page', 'page_touched', $this->pageCond(), __METHOD__ );
4639                 return $touched;
4640         }
4641
4642         /**
4643          * Get the timestamp when this page was updated since the user last saw it.
4644          *
4645          * @param User $user
4646          * @return string|null
4647          */
4648         public function getNotificationTimestamp( $user = null ) {
4649                 global $wgUser;
4650
4651                 // Assume current user if none given
4652                 if ( !$user ) {
4653                         $user = $wgUser;
4654                 }
4655                 // Check cache first
4656                 $uid = $user->getId();
4657                 if ( !$uid ) {
4658                         return false;
4659                 }
4660                 // avoid isset here, as it'll return false for null entries
4661                 if ( array_key_exists( $uid, $this->mNotificationTimestamp ) ) {
4662                         return $this->mNotificationTimestamp[$uid];
4663                 }
4664                 // Don't cache too much!
4665                 if ( count( $this->mNotificationTimestamp ) >= self::CACHE_MAX ) {
4666                         $this->mNotificationTimestamp = [];
4667                 }
4668
4669                 $store = MediaWikiServices::getInstance()->getWatchedItemStore();
4670                 $watchedItem = $store->getWatchedItem( $user, $this );
4671                 if ( $watchedItem ) {
4672                         $this->mNotificationTimestamp[$uid] = $watchedItem->getNotificationTimestamp();
4673                 } else {
4674                         $this->mNotificationTimestamp[$uid] = false;
4675                 }
4676
4677                 return $this->mNotificationTimestamp[$uid];
4678         }
4679
4680         /**
4681          * Generate strings used for xml 'id' names in monobook tabs
4682          *
4683          * @param string $prepend Defaults to 'nstab-'
4684          * @return string XML 'id' name
4685          */
4686         public function getNamespaceKey( $prepend = 'nstab-' ) {
4687                 global $wgContLang;
4688                 // Gets the subject namespace if this title
4689                 $namespace = MWNamespace::getSubject( $this->getNamespace() );
4690                 // Checks if canonical namespace name exists for namespace
4691                 if ( MWNamespace::exists( $this->getNamespace() ) ) {
4692                         // Uses canonical namespace name
4693                         $namespaceKey = MWNamespace::getCanonicalName( $namespace );
4694                 } else {
4695                         // Uses text of namespace
4696                         $namespaceKey = $this->getSubjectNsText();
4697                 }
4698                 // Makes namespace key lowercase
4699                 $namespaceKey = $wgContLang->lc( $namespaceKey );
4700                 // Uses main
4701                 if ( $namespaceKey == '' ) {
4702                         $namespaceKey = 'main';
4703                 }
4704                 // Changes file to image for backwards compatibility
4705                 if ( $namespaceKey == 'file' ) {
4706                         $namespaceKey = 'image';
4707                 }
4708                 return $prepend . $namespaceKey;
4709         }
4710
4711         /**
4712          * Get all extant redirects to this Title
4713          *
4714          * @param int|null $ns Single namespace to consider; null to consider all namespaces
4715          * @return Title[] Array of Title redirects to this title
4716          */
4717         public function getRedirectsHere( $ns = null ) {
4718                 $redirs = [];
4719
4720                 $dbr = wfGetDB( DB_REPLICA );
4721                 $where = [
4722                         'rd_namespace' => $this->getNamespace(),
4723                         'rd_title' => $this->getDBkey(),
4724                         'rd_from = page_id'
4725                 ];
4726                 if ( $this->isExternal() ) {
4727                         $where['rd_interwiki'] = $this->getInterwiki();
4728                 } else {
4729                         $where[] = 'rd_interwiki = ' . $dbr->addQuotes( '' ) . ' OR rd_interwiki IS NULL';
4730                 }
4731                 if ( !is_null( $ns ) ) {
4732                         $where['page_namespace'] = $ns;
4733                 }
4734
4735                 $res = $dbr->select(
4736                         [ 'redirect', 'page' ],
4737                         [ 'page_namespace', 'page_title' ],
4738                         $where,
4739                         __METHOD__
4740                 );
4741
4742                 foreach ( $res as $row ) {
4743                         $redirs[] = self::newFromRow( $row );
4744                 }
4745                 return $redirs;
4746         }
4747
4748         /**
4749          * Check if this Title is a valid redirect target
4750          *
4751          * @return bool
4752          */
4753         public function isValidRedirectTarget() {
4754                 global $wgInvalidRedirectTargets;
4755
4756                 if ( $this->isSpecialPage() ) {
4757                         // invalid redirect targets are stored in a global array, but explicitly disallow Userlogout here
4758                         if ( $this->isSpecial( 'Userlogout' ) ) {
4759                                 return false;
4760                         }
4761
4762                         foreach ( $wgInvalidRedirectTargets as $target ) {
4763                                 if ( $this->isSpecial( $target ) ) {
4764                                         return false;
4765                                 }
4766                         }
4767                 }
4768
4769                 return true;
4770         }
4771
4772         /**
4773          * Get a backlink cache object
4774          *
4775          * @return BacklinkCache
4776          */
4777         public function getBacklinkCache() {
4778                 return BacklinkCache::get( $this );
4779         }
4780
4781         /**
4782          * Whether the magic words __INDEX__ and __NOINDEX__ function for this page.
4783          *
4784          * @return bool
4785          */
4786         public function canUseNoindex() {
4787                 global $wgExemptFromUserRobotsControl;
4788
4789                 $bannedNamespaces = is_null( $wgExemptFromUserRobotsControl )
4790                         ? MWNamespace::getContentNamespaces()
4791                         : $wgExemptFromUserRobotsControl;
4792
4793                 return !in_array( $this->mNamespace, $bannedNamespaces );
4794         }
4795
4796         /**
4797          * Returns the raw sort key to be used for categories, with the specified
4798          * prefix.  This will be fed to Collation::getSortKey() to get a
4799          * binary sortkey that can be used for actual sorting.
4800          *
4801          * @param string $prefix The prefix to be used, specified using
4802          *   {{defaultsort:}} or like [[Category:Foo|prefix]].  Empty for no
4803          *   prefix.
4804          * @return string
4805          */
4806         public function getCategorySortkey( $prefix = '' ) {
4807                 $unprefixed = $this->getText();
4808
4809                 // Anything that uses this hook should only depend
4810                 // on the Title object passed in, and should probably
4811                 // tell the users to run updateCollations.php --force
4812                 // in order to re-sort existing category relations.
4813                 Hooks::run( 'GetDefaultSortkey', [ $this, &$unprefixed ] );
4814                 if ( $prefix !== '' ) {
4815                         # Separate with a line feed, so the unprefixed part is only used as
4816                         # a tiebreaker when two pages have the exact same prefix.
4817                         # In UCA, tab is the only character that can sort above LF
4818                         # so we strip both of them from the original prefix.
4819                         $prefix = strtr( $prefix, "\n\t", '  ' );
4820                         return "$prefix\n$unprefixed";
4821                 }
4822                 return $unprefixed;
4823         }
4824
4825         /**
4826          * Returns the page language code saved in the database, if $wgPageLanguageUseDB is set
4827          * to true in LocalSettings.php, otherwise returns false. If there is no language saved in
4828          * the db, it will return NULL.
4829          *
4830          * @return string|null|bool
4831          */
4832         private function getDbPageLanguageCode() {
4833                 global $wgPageLanguageUseDB;
4834
4835                 // check, if the page language could be saved in the database, and if so and
4836                 // the value is not requested already, lookup the page language using LinkCache
4837                 if ( $wgPageLanguageUseDB && $this->mDbPageLanguage === false ) {
4838                         $linkCache = LinkCache::singleton();
4839                         $linkCache->addLinkObj( $this );
4840                         $this->mDbPageLanguage = $linkCache->getGoodLinkFieldObj( $this, 'lang' );
4841                 }
4842
4843                 return $this->mDbPageLanguage;
4844         }
4845
4846         /**
4847          * Get the language in which the content of this page is written in
4848          * wikitext. Defaults to $wgContLang, but in certain cases it can be
4849          * e.g. $wgLang (such as special pages, which are in the user language).
4850          *
4851          * @since 1.18
4852          * @return Language
4853          */
4854         public function getPageLanguage() {
4855                 global $wgLang, $wgLanguageCode;
4856                 if ( $this->isSpecialPage() ) {
4857                         // special pages are in the user language
4858                         return $wgLang;
4859                 }
4860
4861                 // Checking if DB language is set
4862                 $dbPageLanguage = $this->getDbPageLanguageCode();
4863                 if ( $dbPageLanguage ) {
4864                         return wfGetLangObj( $dbPageLanguage );
4865                 }
4866
4867                 if ( !$this->mPageLanguage || $this->mPageLanguage[1] !== $wgLanguageCode ) {
4868                         // Note that this may depend on user settings, so the cache should
4869                         // be only per-request.
4870                         // NOTE: ContentHandler::getPageLanguage() may need to load the
4871                         // content to determine the page language!
4872                         // Checking $wgLanguageCode hasn't changed for the benefit of unit
4873                         // tests.
4874                         $contentHandler = ContentHandler::getForTitle( $this );
4875                         $langObj = $contentHandler->getPageLanguage( $this );
4876                         $this->mPageLanguage = [ $langObj->getCode(), $wgLanguageCode ];
4877                 } else {
4878                         $langObj = wfGetLangObj( $this->mPageLanguage[0] );
4879                 }
4880
4881                 return $langObj;
4882         }
4883
4884         /**
4885          * Get the language in which the content of this page is written when
4886          * viewed by user. Defaults to $wgContLang, but in certain cases it can be
4887          * e.g. $wgLang (such as special pages, which are in the user language).
4888          *
4889          * @since 1.20
4890          * @return Language
4891          */
4892         public function getPageViewLanguage() {
4893                 global $wgLang;
4894
4895                 if ( $this->isSpecialPage() ) {
4896                         // If the user chooses a variant, the content is actually
4897                         // in a language whose code is the variant code.
4898                         $variant = $wgLang->getPreferredVariant();
4899                         if ( $wgLang->getCode() !== $variant ) {
4900                                 return Language::factory( $variant );
4901                         }
4902
4903                         return $wgLang;
4904                 }
4905
4906                 // Checking if DB language is set
4907                 $dbPageLanguage = $this->getDbPageLanguageCode();
4908                 if ( $dbPageLanguage ) {
4909                         $pageLang = wfGetLangObj( $dbPageLanguage );
4910                         $variant = $pageLang->getPreferredVariant();
4911                         if ( $pageLang->getCode() !== $variant ) {
4912                                 $pageLang = Language::factory( $variant );
4913                         }
4914
4915                         return $pageLang;
4916                 }
4917
4918                 // @note Can't be cached persistently, depends on user settings.
4919                 // @note ContentHandler::getPageViewLanguage() may need to load the
4920                 //   content to determine the page language!
4921                 $contentHandler = ContentHandler::getForTitle( $this );
4922                 $pageLang = $contentHandler->getPageViewLanguage( $this );
4923                 return $pageLang;
4924         }
4925
4926         /**
4927          * Get a list of rendered edit notices for this page.
4928          *
4929          * Array is keyed by the original message key, and values are rendered using parseAsBlock, so
4930          * they will already be wrapped in paragraphs.
4931          *
4932          * @since 1.21
4933          * @param int $oldid Revision ID that's being edited
4934          * @return array
4935          */
4936         public function getEditNotices( $oldid = 0 ) {
4937                 $notices = [];
4938
4939                 // Optional notice for the entire namespace
4940                 $editnotice_ns = 'editnotice-' . $this->getNamespace();
4941                 $msg = wfMessage( $editnotice_ns );
4942                 if ( $msg->exists() ) {
4943                         $html = $msg->parseAsBlock();
4944                         // Edit notices may have complex logic, but output nothing (T91715)
4945                         if ( trim( $html ) !== '' ) {
4946                                 $notices[$editnotice_ns] = Html::rawElement(
4947                                         'div',
4948                                         [ 'class' => [
4949                                                 'mw-editnotice',
4950                                                 'mw-editnotice-namespace',
4951                                                 Sanitizer::escapeClass( "mw-$editnotice_ns" )
4952                                         ] ],
4953                                         $html
4954                                 );
4955                         }
4956                 }
4957
4958                 if ( MWNamespace::hasSubpages( $this->getNamespace() ) ) {
4959                         // Optional notice for page itself and any parent page
4960                         $parts = explode( '/', $this->getDBkey() );
4961                         $editnotice_base = $editnotice_ns;
4962                         while ( count( $parts ) > 0 ) {
4963                                 $editnotice_base .= '-' . array_shift( $parts );
4964                                 $msg = wfMessage( $editnotice_base );
4965                                 if ( $msg->exists() ) {
4966                                         $html = $msg->parseAsBlock();
4967                                         if ( trim( $html ) !== '' ) {
4968                                                 $notices[$editnotice_base] = Html::rawElement(
4969                                                         'div',
4970                                                         [ 'class' => [
4971                                                                 'mw-editnotice',
4972                                                                 'mw-editnotice-base',
4973                                                                 Sanitizer::escapeClass( "mw-$editnotice_base" )
4974                                                         ] ],
4975                                                         $html
4976                                                 );
4977                                         }
4978                                 }
4979                         }
4980                 } else {
4981                         // Even if there are no subpages in namespace, we still don't want "/" in MediaWiki message keys
4982                         $editnoticeText = $editnotice_ns . '-' . strtr( $this->getDBkey(), '/', '-' );
4983                         $msg = wfMessage( $editnoticeText );
4984                         if ( $msg->exists() ) {
4985                                 $html = $msg->parseAsBlock();
4986                                 if ( trim( $html ) !== '' ) {
4987                                         $notices[$editnoticeText] = Html::rawElement(
4988                                                 'div',
4989                                                 [ 'class' => [
4990                                                         'mw-editnotice',
4991                                                         'mw-editnotice-page',
4992                                                         Sanitizer::escapeClass( "mw-$editnoticeText" )
4993                                                 ] ],
4994                                                 $html
4995                                         );
4996                                 }
4997                         }
4998                 }
4999
5000                 Hooks::run( 'TitleGetEditNotices', [ $this, $oldid, &$notices ] );
5001                 return $notices;
5002         }
5003
5004         /**
5005          * @return array
5006          */
5007         public function __sleep() {
5008                 return [
5009                         'mNamespace',
5010                         'mDbkeyform',
5011                         'mFragment',
5012                         'mInterwiki',
5013                         'mLocalInterwiki',
5014                         'mUserCaseDBKey',
5015                         'mDefaultNamespace',
5016                 ];
5017         }
5018
5019         public function __wakeup() {
5020                 $this->mArticleID = ( $this->mNamespace >= 0 ) ? -1 : 0;
5021                 $this->mUrlform = wfUrlencode( $this->mDbkeyform );
5022                 $this->mTextform = strtr( $this->mDbkeyform, '_', ' ' );
5023         }
5024
5025 }