includes/Revision.php

   1 <?php
   2
   3 /**
   4  * @todo document
   5  */
   6 class Revision {
   7         const DELETED_TEXT = 1;
   8         const DELETED_COMMENT = 2;
   9         const DELETED_USER = 4;
  10         const DELETED_RESTRICTED = 8;
  11         // Convenience field
  12         const SUPPRESSED_USER = 12;
  13         // Audience options for Revision::getText()
  14         const FOR_PUBLIC = 1;
  15         const FOR_THIS_USER = 2;
  16         const RAW = 3;
  17
  18         /**
  19          * Load a page revision from a given revision ID number.
  20          * Returns null if no such revision can be found.
  21          *
  22          * @param $id Integer
  23          * @return Revision or null
  24          */
  25         public static function newFromId( $id ) {
  26                 return Revision::newFromConds(
  27                         array( 'page_id=rev_page',
  28                                    'rev_id' => intval( $id ) ) );
  29         }
  30
  31         /**
  32          * Load either the current, or a specified, revision
  33          * that's attached to a given title. If not attached
  34          * to that title, will return null.
  35          *
  36          * @param $title Title
  37          * @param $id Integer (optional)
  38          * @return Revision or null
  39          */
  40         public static function newFromTitle( $title, $id = 0 ) {
  41                 $conds = array(
  42                         'page_namespace' => $title->getNamespace(),
  43                         'page_title'     => $title->getDBkey()
  44                 );
  45                 if ( $id ) {
  46                         // Use the specified ID
  47                         $conds['rev_id'] = $id;
  48                 } elseif ( wfGetLB()->getServerCount() > 1 ) {
  49                         // Get the latest revision ID from the master
  50                         $dbw = wfGetDB( DB_MASTER );
  51                         $latest = $dbw->selectField( 'page', 'page_latest', $conds, __METHOD__ );
  52                         if ( $latest === false ) {
  53                                 return null; // page does not exist
  54                         }
  55                         $conds['rev_id'] = $latest;
  56                 } else {
  57                         // Use a join to get the latest revision
  58                         $conds[] = 'rev_id=page_latest';
  59                 }
  60                 $conds[] = 'page_id=rev_page';
  61                 return Revision::newFromConds( $conds );
  62         }
  63
  64         /**
  65          * Load either the current, or a specified, revision
  66          * that's attached to a given page ID.
  67          * Returns null if no such revision can be found.
  68          *
  69          * @param $revId Integer
  70          * @param $pageId Integer (optional)
  71          * @return Revision or null
  72          */
  73         public static function newFromPageId( $pageId, $revId = 0 ) {
  74                 $conds = array( 'page_id' => $pageId );
  75                 if ( $revId ) {
  76                         $conds['rev_id'] = $revId;
  77                 } elseif ( wfGetLB()->getServerCount() > 1 ) {
  78                         // Get the latest revision ID from the master
  79                         $dbw = wfGetDB( DB_MASTER );
  80                         $latest = $dbw->selectField( 'page', 'page_latest', $conds, __METHOD__ );
  81                         if ( $latest === false ) {
  82                                 return null; // page does not exist
  83                         }
  84                         $conds['rev_id'] = $latest;
  85                 } else {
  86                         $conds[] = 'rev_id = page_latest';
  87                 }
  88                 $conds[] = 'page_id=rev_page';
  89                 return Revision::newFromConds( $conds );
  90         }
  91
  92         /**
  93          * Make a fake revision object from an archive table row. This is queried
  94          * for permissions or even inserted (as in Special:Undelete)
  95          * @todo FIXME: Should be a subclass for RevisionDelete. [TS]
  96          *
  97          * @param $row
  98          * @param $overrides array
  99          *
 100          * @return Revision
 101          */
 102         public static function newFromArchiveRow( $row, $overrides = array() ) {
 103                 $attribs = $overrides + array(
 104                         'page'       => isset( $row->ar_page_id ) ? $row->ar_page_id : null,
 105                         'id'         => isset( $row->ar_rev_id ) ? $row->ar_rev_id : null,
 106                         'comment'    => $row->ar_comment,
 107                         'user'       => $row->ar_user,
 108                         'user_text'  => $row->ar_user_text,
 109                         'timestamp'  => $row->ar_timestamp,
 110                         'minor_edit' => $row->ar_minor_edit,
 111                         'text_id'    => isset( $row->ar_text_id ) ? $row->ar_text_id : null,
 112                         'deleted'    => $row->ar_deleted,
 113                         'len'        => $row->ar_len
 114                 );
 115                 if ( isset( $row->ar_text ) && !$row->ar_text_id ) {
 116                         // Pre-1.5 ar_text row
 117                         $attribs['text'] = self::getRevisionText( $row, 'ar_' );
 118                         if ( $attribs['text'] === false ) {
 119                                 throw new MWException( 'Unable to load text from archive row (possibly bug 22624)' );
 120                         }
 121                 }
 122                 return new self( $attribs );
 123         }
 124
 125         /**
 126          * @since 1.19
 127          *
 128          * @param $row
 129          * @return Revision
 130          */
 131         public static function newFromRow( $row ) {
 132                 return new self( $row );
 133         }
 134
 135         /**
 136          * Load a page revision from a given revision ID number.
 137          * Returns null if no such revision can be found.
 138          *
 139          * @param $db DatabaseBase
 140          * @param $id Integer
 141          * @return Revision or null
 142          */
 143         public static function loadFromId( $db, $id ) {
 144                 return Revision::loadFromConds( $db,
 145                         array( 'page_id=rev_page',
 146                                    'rev_id' => intval( $id ) ) );
 147         }
 148
 149         /**
 150          * Load either the current, or a specified, revision
 151          * that's attached to a given page. If not attached
 152          * to that page, will return null.
 153          *
 154          * @param $db DatabaseBase
 155          * @param $pageid Integer
 156          * @param $id Integer
 157          * @return Revision or null
 158          */
 159         public static function loadFromPageId( $db, $pageid, $id = 0 ) {
 160                 $conds = array( 'page_id=rev_page','rev_page' => intval( $pageid ), 'page_id'=>intval( $pageid ) );
 161                 if( $id ) {
 162                         $conds['rev_id'] = intval( $id );
 163                 } else {
 164                         $conds[] = 'rev_id=page_latest';
 165                 }
 166                 return Revision::loadFromConds( $db, $conds );
 167         }
 168
 169         /**
 170          * Load either the current, or a specified, revision
 171          * that's attached to a given page. If not attached
 172          * to that page, will return null.
 173          *
 174          * @param $db DatabaseBase
 175          * @param $title Title
 176          * @param $id Integer
 177          * @return Revision or null
 178          */
 179         public static function loadFromTitle( $db, $title, $id = 0 ) {
 180                 if( $id ) {
 181                         $matchId = intval( $id );
 182                 } else {
 183                         $matchId = 'page_latest';
 184                 }
 185                 return Revision::loadFromConds(
 186                         $db,
 187                         array( "rev_id=$matchId",
 188                                    'page_id=rev_page',
 189                                    'page_namespace' => $title->getNamespace(),
 190                                    'page_title'     => $title->getDBkey() ) );
 191         }
 192
 193         /**
 194          * Load the revision for the given title with the given timestamp.
 195          * WARNING: Timestamps may in some circumstances not be unique,
 196          * so this isn't the best key to use.
 197          *
 198          * @param $db DatabaseBase
 199          * @param $title Title
 200          * @param $timestamp String
 201          * @return Revision or null
 202          */
 203         public static function loadFromTimestamp( $db, $title, $timestamp ) {
 204                 return Revision::loadFromConds(
 205                         $db,
 206                         array( 'rev_timestamp'  => $db->timestamp( $timestamp ),
 207                                    'page_id=rev_page',
 208                                    'page_namespace' => $title->getNamespace(),
 209                                    'page_title'     => $title->getDBkey() ) );
 210         }
 211
 212         /**
 213          * Given a set of conditions, fetch a revision.
 214          *
 215          * @param $conditions Array
 216          * @return Revision or null
 217          */
 218         public static function newFromConds( $conditions ) {
 219                 $db = wfGetDB( DB_SLAVE );
 220                 $row = Revision::loadFromConds( $db, $conditions );
 221                 if( is_null( $row ) && wfGetLB()->getServerCount() > 1 ) {
 222                         $dbw = wfGetDB( DB_MASTER );
 223                         $row = Revision::loadFromConds( $dbw, $conditions );
 224                 }
 225                 return $row;
 226         }
 227
 228         /**
 229          * Given a set of conditions, fetch a revision from
 230          * the given database connection.
 231          *
 232          * @param $db DatabaseBase
 233          * @param $conditions Array
 234          * @return Revision or null
 235          */
 236         private static function loadFromConds( $db, $conditions ) {
 237                 $res = Revision::fetchFromConds( $db, $conditions );
 238                 if( $res ) {
 239                         $row = $res->fetchObject();
 240                         $res->free();
 241                         if( $row ) {
 242                                 $ret = new Revision( $row );
 243                                 return $ret;
 244                         }
 245                 }
 246                 $ret = null;
 247                 return $ret;
 248         }
 249
 250         /**
 251          * Return a wrapper for a series of database rows to
 252          * fetch all of a given page's revisions in turn.
 253          * Each row can be fed to the constructor to get objects.
 254          *
 255          * @param $title Title
 256          * @return ResultWrapper
 257          */
 258         public static function fetchRevision( $title ) {
 259                 return Revision::fetchFromConds(
 260                         wfGetDB( DB_SLAVE ),
 261                         array( 'rev_id=page_latest',
 262                                    'page_namespace' => $title->getNamespace(),
 263                                    'page_title'     => $title->getDBkey(),
 264                                    'page_id=rev_page' ) );
 265         }
 266
 267         /**
 268          * Given a set of conditions, return a ResultWrapper
 269          * which will return matching database rows with the
 270          * fields necessary to build Revision objects.
 271          *
 272          * @param $db DatabaseBase
 273          * @param $conditions Array
 274          * @return ResultWrapper
 275          */
 276         private static function fetchFromConds( $db, $conditions ) {
 277                 $fields = self::selectFields();
 278                 $fields[] = 'page_namespace';
 279                 $fields[] = 'page_title';
 280                 $fields[] = 'page_latest';
 281                 return $db->select(
 282                         array( 'page', 'revision' ),
 283                         $fields,
 284                         $conditions,
 285                         __METHOD__,
 286                         array( 'LIMIT' => 1 ) );
 287         }
 288
 289         /**
 290          * Return the list of revision fields that should be selected to create
 291          * a new revision.
 292          */
 293         public static function selectFields() {
 294                 return array(
 295                         'rev_id',
 296                         'rev_page',
 297                         'rev_text_id',
 298                         'rev_timestamp',
 299                         'rev_comment',
 300                         'rev_user_text,'.
 301                         'rev_user',
 302                         'rev_minor_edit',
 303                         'rev_deleted',
 304                         'rev_len',
 305                         'rev_parent_id'
 306                 );
 307         }
 308
 309         /**
 310          * Return the list of text fields that should be selected to read the
 311          * revision text
 312          */
 313         static function selectTextFields() {
 314                 return array(
 315                         'old_text',
 316                         'old_flags'
 317                 );
 318         }
 319
 320         /**
 321          * Return the list of page fields that should be selected from page table
 322          */
 323         static function selectPageFields() {
 324                 return array(
 325                         'page_namespace',
 326                         'page_title',
 327                         'page_latest'
 328                 );
 329         }
 330
 331         /**
 332          * Constructor
 333          *
 334          * @param $row Mixed: either a database row or an array
 335          * @access private
 336          */
 337         function __construct( $row ) {
 338                 if( is_object( $row ) ) {
 339                         $this->mId        = intval( $row->rev_id );
 340                         $this->mPage      = intval( $row->rev_page );
 341                         $this->mTextId    = intval( $row->rev_text_id );
 342                         $this->mComment   =         $row->rev_comment;
 343                         $this->mUserText  =         $row->rev_user_text;
 344                         $this->mUser      = intval( $row->rev_user );
 345                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 346                         $this->mTimestamp =         $row->rev_timestamp;
 347                         $this->mDeleted   = intval( $row->rev_deleted );
 348
 349                         if( !isset( $row->rev_parent_id ) ) {
 350                                 $this->mParentId = is_null($row->rev_parent_id) ? null : 0;
 351                         } else {
 352                                 $this->mParentId  = intval( $row->rev_parent_id );
 353                         }
 354
 355                         if( !isset( $row->rev_len ) || is_null( $row->rev_len ) ) {
 356                                 $this->mSize = null;
 357                         } else {
 358                                 $this->mSize = intval( $row->rev_len );
 359                         }
 360
 361                         if( isset( $row->page_latest ) ) {
 362                                 $this->mCurrent = ( $row->rev_id == $row->page_latest );
 363                                 $this->mTitle = Title::newFromRow( $row );
 364                         } else {
 365                                 $this->mCurrent = false;
 366                                 $this->mTitle = null;
 367                         }
 368
 369                         // Lazy extraction...
 370                         $this->mText      = null;
 371                         if( isset( $row->old_text ) ) {
 372                                 $this->mTextRow = $row;
 373                         } else {
 374                                 // 'text' table row entry will be lazy-loaded
 375                                 $this->mTextRow = null;
 376                         }
 377                 } elseif( is_array( $row ) ) {
 378                         // Build a new revision to be saved...
 379                         global $wgUser;
 380
 381                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 382                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 383                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 384                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 385                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 386                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 387                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestamp( TS_MW );
 388                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 389                         $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
 390                         $this->mParentId  = isset( $row['parent_id']  ) ? intval( $row['parent_id']  ) : null;
 391
 392                         // Enforce spacing trimming on supplied text
 393                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 394                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 395                         $this->mTextRow   = null;
 396
 397                         $this->mTitle     = null; # Load on demand if needed
 398                         $this->mCurrent   = false;
 399                         # If we still have no len_size, see it we have the text to figure it out
 400                         if ( !$this->mSize )
 401                                 $this->mSize      = is_null( $this->mText ) ? null : strlen( $this->mText );
 402                 } else {
 403                         throw new MWException( 'Revision constructor passed invalid row format.' );
 404                 }
 405                 $this->mUnpatrolled = null;
 406         }
 407
 408         /**
 409          * Get revision ID
 410          *
 411          * @return Integer
 412          */
 413         public function getId() {
 414                 return $this->mId;
 415         }
 416
 417         /**
 418          * Get text row ID
 419          *
 420          * @return Integer
 421          */
 422         public function getTextId() {
 423                 return $this->mTextId;
 424         }
 425
 426         /**
 427          * Get parent revision ID (the original previous page revision)
 428          *
 429          * @return Integer
 430          */
 431         public function getParentId() {
 432                 return $this->mParentId;
 433         }
 434
 435         /**
 436          * Returns the length of the text in this revision, or null if unknown.
 437          *
 438          * @return Integer
 439          */
 440         public function getSize() {
 441                 return $this->mSize;
 442         }
 443
 444         /**
 445          * Returns the title of the page associated with this entry.
 446          *
 447          * @return Title
 448          */
 449         public function getTitle() {
 450                 if( isset( $this->mTitle ) ) {
 451                         return $this->mTitle;
 452                 }
 453                 $dbr = wfGetDB( DB_SLAVE );
 454                 $row = $dbr->selectRow(
 455                         array( 'page', 'revision' ),
 456                         array( 'page_namespace', 'page_title' ),
 457                         array( 'page_id=rev_page',
 458                                    'rev_id' => $this->mId ),
 459                         'Revision::getTitle' );
 460                 if( $row ) {
 461                         $this->mTitle = Title::makeTitle( $row->page_namespace, $row->page_title );
 462                 }
 463                 return $this->mTitle;
 464         }
 465
 466         /**
 467          * Set the title of the revision
 468          *
 469          * @param $title Title
 470          */
 471         public function setTitle( $title ) {
 472                 $this->mTitle = $title;
 473         }
 474
 475         /**
 476          * Get the page ID
 477          *
 478          * @return Integer
 479          */
 480         public function getPage() {
 481                 return $this->mPage;
 482         }
 483
 484         /**
 485          * Fetch revision's user id if it's available to the specified audience.
 486          * If the specified audience does not have access to it, zero will be
 487          * returned.
 488          *
 489          * @param $audience Integer: one of:
 490          *      Revision::FOR_PUBLIC       to be displayed to all users
 491          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 492          *      Revision::RAW              get the ID regardless of permissions
 493          *
 494          *
 495          * @return Integer
 496          */
 497         public function getUser( $audience = self::FOR_PUBLIC ) {
 498                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 499                         return 0;
 500                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER ) ) {
 501                         return 0;
 502                 } else {
 503                         return $this->mUser;
 504                 }
 505         }
 506
 507         /**
 508          * Fetch revision's user id without regard for the current user's permissions
 509          *
 510          * @return String
 511          */
 512         public function getRawUser() {
 513                 return $this->mUser;
 514         }
 515
 516         /**
 517          * Fetch revision's username if it's available to the specified audience.
 518          * If the specified audience does not have access to the username, an
 519          * empty string will be returned.
 520          *
 521          * @param $audience Integer: one of:
 522          *      Revision::FOR_PUBLIC       to be displayed to all users
 523          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 524          *      Revision::RAW              get the text regardless of permissions
 525          *
 526          * @return string
 527          */
 528         public function getUserText( $audience = self::FOR_PUBLIC ) {
 529                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 530                         return '';
 531                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER ) ) {
 532                         return '';
 533                 } else {
 534                         return $this->mUserText;
 535                 }
 536         }
 537
 538         /**
 539          * Fetch revision's username without regard for view restrictions
 540          *
 541          * @return String
 542          */
 543         public function getRawUserText() {
 544                 return $this->mUserText;
 545         }
 546
 547         /**
 548          * Fetch revision comment if it's available to the specified audience.
 549          * If the specified audience does not have access to the comment, an
 550          * empty string will be returned.
 551          *
 552          * @param $audience Integer: one of:
 553          *      Revision::FOR_PUBLIC       to be displayed to all users
 554          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 555          *      Revision::RAW              get the text regardless of permissions
 556          *
 557          * @return String
 558          */
 559         function getComment( $audience = self::FOR_PUBLIC ) {
 560                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_COMMENT ) ) {
 561                         return '';
 562                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_COMMENT ) ) {
 563                         return '';
 564                 } else {
 565                         return $this->mComment;
 566                 }
 567         }
 568
 569         /**
 570          * Fetch revision comment without regard for the current user's permissions
 571          *
 572          * @return String
 573          */
 574         public function getRawComment() {
 575                 return $this->mComment;
 576         }
 577
 578         /**
 579          * @return Boolean
 580          */
 581         public function isMinor() {
 582                 return (bool)$this->mMinorEdit;
 583         }
 584
 585         /**
 586          * @return Integer rcid of the unpatrolled row, zero if there isn't one
 587          */
 588         public function isUnpatrolled() {
 589                 if( $this->mUnpatrolled !== null ) {
 590                         return $this->mUnpatrolled;
 591                 }
 592                 $dbr = wfGetDB( DB_SLAVE );
 593                 $this->mUnpatrolled = $dbr->selectField( 'recentchanges',
 594                         'rc_id',
 595                         array( // Add redundant user,timestamp condition so we can use the existing index
 596                                 'rc_user_text'  => $this->getRawUserText(),
 597                                 'rc_timestamp'  => $dbr->timestamp( $this->getTimestamp() ),
 598                                 'rc_this_oldid' => $this->getId(),
 599                                 'rc_patrolled'  => 0
 600                         ),
 601                         __METHOD__
 602                 );
 603                 return (int)$this->mUnpatrolled;
 604         }
 605
 606         /**
 607          * @param $field int one of DELETED_* bitfield constants
 608          *
 609          * @return Boolean
 610          */
 611         public function isDeleted( $field ) {
 612                 return ( $this->mDeleted & $field ) == $field;
 613         }
 614
 615         /**
 616          * Get the deletion bitfield of the revision
 617          *
 618          * @return int
 619          */
 620         public function getVisibility() {
 621                 return (int)$this->mDeleted;
 622         }
 623
 624         /**
 625          * Fetch revision text if it's available to the specified audience.
 626          * If the specified audience does not have the ability to view this
 627          * revision, an empty string will be returned.
 628          *
 629          * @param $audience Integer: one of:
 630          *      Revision::FOR_PUBLIC       to be displayed to all users
 631          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 632          *      Revision::RAW              get the text regardless of permissions
 633          *
 634          * @return String
 635          */
 636         public function getText( $audience = self::FOR_PUBLIC ) {
 637                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_TEXT ) ) {
 638                         return '';
 639                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_TEXT ) ) {
 640                         return '';
 641                 } else {
 642                         return $this->getRawText();
 643                 }
 644         }
 645
 646         /**
 647          * Alias for getText(Revision::FOR_THIS_USER)
 648          *
 649          * @deprecated since 1.17
 650          * @return String
 651          */
 652         public function revText() {
 653                 wfDeprecated( __METHOD__ );
 654                 return $this->getText( self::FOR_THIS_USER );
 655         }
 656
 657         /**
 658          * Fetch revision text without regard for view restrictions
 659          *
 660          * @return String
 661          */
 662         public function getRawText() {
 663                 if( is_null( $this->mText ) ) {
 664                         // Revision text is immutable. Load on demand:
 665                         $this->mText = $this->loadText();
 666                 }
 667                 return $this->mText;
 668         }
 669
 670         /**
 671          * @return String
 672          */
 673         public function getTimestamp() {
 674                 return wfTimestamp( TS_MW, $this->mTimestamp );
 675         }
 676
 677         /**
 678          * @return Boolean
 679          */
 680         public function isCurrent() {
 681                 return $this->mCurrent;
 682         }
 683
 684         /**
 685          * Get previous revision for this title
 686          *
 687          * @return Revision or null
 688          */
 689         public function getPrevious() {
 690                 if( $this->getTitle() ) {
 691                         $prev = $this->getTitle()->getPreviousRevisionID( $this->getId() );
 692                         if( $prev ) {
 693                                 return Revision::newFromTitle( $this->getTitle(), $prev );
 694                         }
 695                 }
 696                 return null;
 697         }
 698
 699         /**
 700          * Get next revision for this title
 701          *
 702          * @return Revision or null
 703          */
 704         public function getNext() {
 705                 if( $this->getTitle() ) {
 706                         $next = $this->getTitle()->getNextRevisionID( $this->getId() );
 707                         if ( $next ) {
 708                                 return Revision::newFromTitle( $this->getTitle(), $next );
 709                         }
 710                 }
 711                 return null;
 712         }
 713
 714         /**
 715          * Get previous revision Id for this page_id
 716          * This is used to populate rev_parent_id on save
 717          *
 718          * @param $db DatabaseBase
 719          * @return Integer
 720          */
 721         private function getPreviousRevisionId( $db ) {
 722                 if( is_null( $this->mPage ) ) {
 723                         return 0;
 724                 }
 725                 # Use page_latest if ID is not given
 726                 if( !$this->mId ) {
 727                         $prevId = $db->selectField( 'page', 'page_latest',
 728                                 array( 'page_id' => $this->mPage ),
 729                                 __METHOD__ );
 730                 } else {
 731                         $prevId = $db->selectField( 'revision', 'rev_id',
 732                                 array( 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ),
 733                                 __METHOD__,
 734                                 array( 'ORDER BY' => 'rev_id DESC' ) );
 735                 }
 736                 return intval( $prevId );
 737         }
 738
 739         /**
 740           * Get revision text associated with an old or archive row
 741           * $row is usually an object from wfFetchRow(), both the flags and the text
 742           * field must be included
 743           *
 744           * @param $row Object: the text data
 745           * @param $prefix String: table prefix (default 'old_')
 746           * @return String: text the text requested or false on failure
 747           */
 748         public static function getRevisionText( $row, $prefix = 'old_' ) {
 749                 wfProfileIn( __METHOD__ );
 750
 751                 # Get data
 752                 $textField = $prefix . 'text';
 753                 $flagsField = $prefix . 'flags';
 754
 755                 if( isset( $row->$flagsField ) ) {
 756                         $flags = explode( ',', $row->$flagsField );
 757                 } else {
 758                         $flags = array();
 759                 }
 760
 761                 if( isset( $row->$textField ) ) {
 762                         $text = $row->$textField;
 763                 } else {
 764                         wfProfileOut( __METHOD__ );
 765                         return false;
 766                 }
 767
 768                 # Use external methods for external objects, text in table is URL-only then
 769                 if ( in_array( 'external', $flags ) ) {
 770                         $url = $text;
 771                         $parts = explode( '://', $url, 2 );
 772                         if( count( $parts ) == 1 || $parts[1] == '' ) {
 773                                 wfProfileOut( __METHOD__ );
 774                                 return false;
 775                         }
 776                         $text = ExternalStore::fetchFromURL( $url );
 777                 }
 778
 779                 // If the text was fetched without an error, convert it
 780                 if ( $text !== false ) {
 781                         if( in_array( 'gzip', $flags ) ) {
 782                                 # Deal with optional compression of archived pages.
 783                                 # This can be done periodically via maintenance/compressOld.php, and
 784                                 # as pages are saved if $wgCompressRevisions is set.
 785                                 $text = gzinflate( $text );
 786                         }
 787
 788                         if( in_array( 'object', $flags ) ) {
 789                                 # Generic compressed storage
 790                                 $obj = unserialize( $text );
 791                                 if ( !is_object( $obj ) ) {
 792                                         // Invalid object
 793                                         wfProfileOut( __METHOD__ );
 794                                         return false;
 795                                 }
 796                                 $text = $obj->getText();
 797                         }
 798
 799                         global $wgLegacyEncoding;
 800                         if( $text !== false && $wgLegacyEncoding
 801                                 && !in_array( 'utf-8', $flags ) && !in_array( 'utf8', $flags ) )
 802                         {
 803                                 # Old revisions kept around in a legacy encoding?
 804                                 # Upconvert on demand.
 805                                 # ("utf8" checked for compatibility with some broken
 806                                 #  conversion scripts 2008-12-30)
 807                                 global $wgContLang;
 808                                 $text = $wgContLang->iconv( $wgLegacyEncoding, 'UTF-8', $text );
 809                         }
 810                 }
 811                 wfProfileOut( __METHOD__ );
 812                 return $text;
 813         }
 814
 815         /**
 816          * If $wgCompressRevisions is enabled, we will compress data.
 817          * The input string is modified in place.
 818          * Return value is the flags field: contains 'gzip' if the
 819          * data is compressed, and 'utf-8' if we're saving in UTF-8
 820          * mode.
 821          *
 822          * @param $text Mixed: reference to a text
 823          * @return String
 824          */
 825         public static function compressRevisionText( &$text ) {
 826                 global $wgCompressRevisions;
 827                 $flags = array();
 828
 829                 # Revisions not marked this way will be converted
 830                 # on load if $wgLegacyCharset is set in the future.
 831                 $flags[] = 'utf-8';
 832
 833                 if( $wgCompressRevisions ) {
 834                         if( function_exists( 'gzdeflate' ) ) {
 835                                 $text = gzdeflate( $text );
 836                                 $flags[] = 'gzip';
 837                         } else {
 838                                 wfDebug( "Revision::compressRevisionText() -- no zlib support, not compressing\n" );
 839                         }
 840                 }
 841                 return implode( ',', $flags );
 842         }
 843
 844         /**
 845          * Insert a new revision into the database, returning the new revision ID
 846          * number on success and dies horribly on failure.
 847          *
 848          * @param $dbw DatabaseBase: (master connection)
 849          * @return Integer
 850          */
 851         public function insertOn( $dbw ) {
 852                 global $wgDefaultExternalStore;
 853
 854                 wfProfileIn( __METHOD__ );
 855
 856                 $data = $this->mText;
 857                 $flags = Revision::compressRevisionText( $data );
 858
 859                 # Write to external storage if required
 860                 if( $wgDefaultExternalStore ) {
 861                         // Store and get the URL
 862                         $data = ExternalStore::insertToDefault( $data );
 863                         if( !$data ) {
 864                                 throw new MWException( "Unable to store text to external storage" );
 865                         }
 866                         if( $flags ) {
 867                                 $flags .= ',';
 868                         }
 869                         $flags .= 'external';
 870                 }
 871
 872                 # Record the text (or external storage URL) to the text table
 873                 if( !isset( $this->mTextId ) ) {
 874                         $old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );
 875                         $dbw->insert( 'text',
 876                                 array(
 877                                         'old_id'    => $old_id,
 878                                         'old_text'  => $data,
 879                                         'old_flags' => $flags,
 880                                 ), __METHOD__
 881                         );
 882                         $this->mTextId = $dbw->insertId();
 883                 }
 884
 885                 if ( $this->mComment === null ) $this->mComment = "";
 886
 887                 # Record the edit in revisions
 888                 $rev_id = isset( $this->mId )
 889                         ? $this->mId
 890                         : $dbw->nextSequenceValue( 'revision_rev_id_seq' );
 891                 $dbw->insert( 'revision',
 892                         array(
 893                                 'rev_id'         => $rev_id,
 894                                 'rev_page'       => $this->mPage,
 895                                 'rev_text_id'    => $this->mTextId,
 896                                 'rev_comment'    => $this->mComment,
 897                                 'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
 898                                 'rev_user'       => $this->mUser,
 899                                 'rev_user_text'  => $this->mUserText,
 900                                 'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
 901                                 'rev_deleted'    => $this->mDeleted,
 902                                 'rev_len'        => $this->mSize,
 903                                 'rev_parent_id'  => is_null($this->mParentId) ?
 904                                         $this->getPreviousRevisionId( $dbw ) : $this->mParentId
 905                         ), __METHOD__
 906                 );
 907
 908                 $this->mId = !is_null( $rev_id ) ? $rev_id : $dbw->insertId();
 909
 910                 wfRunHooks( 'RevisionInsertComplete', array( &$this, $data, $flags ) );
 911
 912                 wfProfileOut( __METHOD__ );
 913                 return $this->mId;
 914         }
 915
 916         /**
 917          * Lazy-load the revision's text.
 918          * Currently hardcoded to the 'text' table storage engine.
 919          *
 920          * @return String
 921          */
 922         protected function loadText() {
 923                 wfProfileIn( __METHOD__ );
 924
 925                 // Caching may be beneficial for massive use of external storage
 926                 global $wgRevisionCacheExpiry, $wgMemc;
 927                 $textId = $this->getTextId();
 928                 $key = wfMemcKey( 'revisiontext', 'textid', $textId );
 929                 if( $wgRevisionCacheExpiry ) {
 930                         $text = $wgMemc->get( $key );
 931                         if( is_string( $text ) ) {
 932                                 wfDebug( __METHOD__ . ": got id $textId from cache\n" );
 933                                 wfProfileOut( __METHOD__ );
 934                                 return $text;
 935                         }
 936                 }
 937
 938                 // If we kept data for lazy extraction, use it now...
 939                 if ( isset( $this->mTextRow ) ) {
 940                         $row = $this->mTextRow;
 941                         $this->mTextRow = null;
 942                 } else {
 943                         $row = null;
 944                 }
 945
 946                 if( !$row ) {
 947                         // Text data is immutable; check slaves first.
 948                         $dbr = wfGetDB( DB_SLAVE );
 949                         $row = $dbr->selectRow( 'text',
 950                                 array( 'old_text', 'old_flags' ),
 951                                 array( 'old_id' => $this->getTextId() ),
 952                                 __METHOD__ );
 953                 }
 954
 955                 if( !$row && wfGetLB()->getServerCount() > 1 ) {
 956                         // Possible slave lag!
 957                         $dbw = wfGetDB( DB_MASTER );
 958                         $row = $dbw->selectRow( 'text',
 959                                 array( 'old_text', 'old_flags' ),
 960                                 array( 'old_id' => $this->getTextId() ),
 961                                 __METHOD__ );
 962                 }
 963
 964                 $text = self::getRevisionText( $row );
 965
 966                 # No negative caching -- negative hits on text rows may be due to corrupted slave servers
 967                 if( $wgRevisionCacheExpiry && $text !== false ) {
 968                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
 969                 }
 970
 971                 wfProfileOut( __METHOD__ );
 972
 973                 return $text;
 974         }
 975
 976         /**
 977          * Create a new null-revision for insertion into a page's
 978          * history. This will not re-save the text, but simply refer
 979          * to the text from the previous version.
 980          *
 981          * Such revisions can for instance identify page rename
 982          * operations and other such meta-modifications.
 983          *
 984          * @param $dbw DatabaseBase
 985          * @param $pageId Integer: ID number of the page to read from
 986          * @param $summary String: revision's summary
 987          * @param $minor Boolean: whether the revision should be considered as minor
 988          * @return Revision|null on error
 989          */
 990         public static function newNullRevision( $dbw, $pageId, $summary, $minor ) {
 991                 wfProfileIn( __METHOD__ );
 992
 993                 $current = $dbw->selectRow(
 994                         array( 'page', 'revision' ),
 995                         array( 'page_latest', 'rev_text_id', 'rev_len' ),
 996                         array(
 997                                 'page_id' => $pageId,
 998                                 'page_latest=rev_id',
 999                                 ),
1000                         __METHOD__ );
1001
1002                 if( $current ) {
1003                         $revision = new Revision( array(
1004                                 'page'       => $pageId,
1005                                 'comment'    => $summary,
1006                                 'minor_edit' => $minor,
1007                                 'text_id'    => $current->rev_text_id,
1008                                 'parent_id'  => $current->page_latest,
1009                                 'len'        => $current->rev_len
1010                                 ) );
1011                 } else {
1012                         $revision = null;
1013                 }
1014
1015                 wfProfileOut( __METHOD__ );
1016                 return $revision;
1017         }
1018
1019         /**
1020          * Determine if the current user is allowed to view a particular
1021          * field of this revision, if it's marked as deleted.
1022          *
1023          * @param $field Integer:one of self::DELETED_TEXT,
1024          *                              self::DELETED_COMMENT,
1025          *                              self::DELETED_USER
1026          * @return Boolean
1027          */
1028         public function userCan( $field ) {
1029                 return self::userCanBitfield( $this->mDeleted, $field );
1030         }
1031
1032         /**
1033          * Determine if the current user is allowed to view a particular
1034          * field of this revision, if it's marked as deleted. This is used
1035          * by various classes to avoid duplication.
1036          *
1037          * @param $bitfield Integer: current field
1038          * @param $field Integer: one of self::DELETED_TEXT = File::DELETED_FILE,
1039          *                               self::DELETED_COMMENT = File::DELETED_COMMENT,
1040          *                               self::DELETED_USER = File::DELETED_USER
1041          * @return Boolean
1042          */
1043         public static function userCanBitfield( $bitfield, $field ) {
1044                 if( $bitfield & $field ) { // aspect is deleted
1045                         global $wgUser;
1046                         if ( $bitfield & self::DELETED_RESTRICTED ) {
1047                                 $permission = 'suppressrevision';
1048                         } elseif ( $field & self::DELETED_TEXT ) {
1049                                 $permission = 'deletedtext';
1050                         } else {
1051                                 $permission = 'deletedhistory';
1052                         }
1053                         wfDebug( "Checking for $permission due to $field match on $bitfield\n" );
1054                         return $wgUser->isAllowed( $permission );
1055                 } else {
1056                         return true;
1057                 }
1058         }
1059
1060         /**
1061          * Get rev_timestamp from rev_id, without loading the rest of the row
1062          *
1063          * @param $title Title
1064          * @param $id Integer
1065          * @return String
1066          */
1067         static function getTimestampFromId( $title, $id ) {
1068                 $dbr = wfGetDB( DB_SLAVE );
1069                 // Casting fix for DB2
1070                 if ( $id == '' ) {
1071                         $id = 0;
1072                 }
1073                 $conds = array( 'rev_id' => $id );
1074                 $conds['rev_page'] = $title->getArticleId();
1075                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1076                 if ( $timestamp === false && wfGetLB()->getServerCount() > 1 ) {
1077                         # Not in slave, try master
1078                         $dbw = wfGetDB( DB_MASTER );
1079                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1080                 }
1081                 return wfTimestamp( TS_MW, $timestamp );
1082         }
1083
1084         /**
1085          * Get count of revisions per page...not very efficient
1086          *
1087          * @param $db DatabaseBase
1088          * @param $id Integer: page id
1089          * @return Integer
1090          */
1091         static function countByPageId( $db, $id ) {
1092                 $row = $db->selectRow( 'revision', 'COUNT(*) AS revCount',
1093                         array( 'rev_page' => $id ), __METHOD__ );
1094                 if( $row ) {
1095                         return $row->revCount;
1096                 }
1097                 return 0;
1098         }
1099
1100         /**
1101          * Get count of revisions per page...not very efficient
1102          *
1103          * @param $db DatabaseBase
1104          * @param $title Title
1105          * @return Integer
1106          */
1107         static function countByTitle( $db, $title ) {
1108                 $id = $title->getArticleId();
1109                 if( $id ) {
1110                         return Revision::countByPageId( $db, $id );
1111                 }
1112                 return 0;
1113         }
1114 }