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
  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                                 // Page does not exist
  54                                 return null;
  55                         }
  56                         $conds['rev_id'] = $latest;
  57                 } else {
  58                         // Use a join to get the latest revision
  59                         $conds[] = 'rev_id=page_latest';
  60                 }
  61                 $conds[] = 'page_id=rev_page';
  62                 return Revision::newFromConds( $conds );
  63         }
  64
  65         /**
  66          * Make a fake revision object from an archive table row. This is queried
  67          * for permissions or even inserted (as in Special:Undelete)
  68          * @todo FIXME: Should be a subclass for RevisionDelete. [TS]
  69          *
  70          * @param $row
  71          * @param $overrides array
  72          *
  73          * @return Revision
  74          */
  75         public static function newFromArchiveRow( $row, $overrides = array() ) {
  76                 $attribs = $overrides + array(
  77                         'page'       => isset( $row->page_id ) ? $row->page_id : null,
  78                         'id'         => isset( $row->ar_rev_id ) ? $row->ar_rev_id : null,
  79                         'comment'    => $row->ar_comment,
  80                         'user'       => $row->ar_user,
  81                         'user_text'  => $row->ar_user_text,
  82                         'timestamp'  => $row->ar_timestamp,
  83                         'minor_edit' => $row->ar_minor_edit,
  84                         'text_id'    => isset( $row->ar_text_id ) ? $row->ar_text_id : null,
  85                         'deleted'    => $row->ar_deleted,
  86                         'len'        => $row->ar_len);
  87                 if ( isset( $row->ar_text ) && !$row->ar_text_id ) {
  88                         // Pre-1.5 ar_text row
  89                         $attribs['text'] = self::getRevisionText( $row, 'ar_' );
  90                         if ( $attribs['text'] === false ) {
  91                                 throw new MWException( 'Unable to load text from archive row (possibly bug 22624)' );
  92                         }
  93                 }
  94                 return new self( $attribs );
  95         }
  96
  97         /**
  98          * Load a page revision from a given revision ID number.
  99          * Returns null if no such revision can be found.
 100          *
 101          * @param $db DatabaseBase
 102          * @param $id Integer
 103          * @return Revision or null
 104          */
 105         public static function loadFromId( $db, $id ) {
 106                 return Revision::loadFromConds( $db,
 107                         array( 'page_id=rev_page',
 108                                    'rev_id' => intval( $id ) ) );
 109         }
 110
 111         /**
 112          * Load either the current, or a specified, revision
 113          * that's attached to a given page. If not attached
 114          * to that page, will return null.
 115          *
 116          * @param $db DatabaseBase
 117          * @param $pageid Integer
 118          * @param $id Integer
 119          * @return Revision or null
 120          */
 121         public static function loadFromPageId( $db, $pageid, $id = 0 ) {
 122                 $conds = array( 'page_id=rev_page','rev_page' => intval( $pageid ), 'page_id'=>intval( $pageid ) );
 123                 if( $id ) {
 124                         $conds['rev_id'] = intval( $id );
 125                 } else {
 126                         $conds[] = 'rev_id=page_latest';
 127                 }
 128                 return Revision::loadFromConds( $db, $conds );
 129         }
 130
 131         /**
 132          * Load either the current, or a specified, revision
 133          * that's attached to a given page. If not attached
 134          * to that page, will return null.
 135          *
 136          * @param $db DatabaseBase
 137          * @param $title Title
 138          * @param $id Integer
 139          * @return Revision or null
 140          */
 141         public static function loadFromTitle( $db, $title, $id = 0 ) {
 142                 if( $id ) {
 143                         $matchId = intval( $id );
 144                 } else {
 145                         $matchId = 'page_latest';
 146                 }
 147                 return Revision::loadFromConds(
 148                         $db,
 149                         array( "rev_id=$matchId",
 150                                    'page_id=rev_page',
 151                                    'page_namespace' => $title->getNamespace(),
 152                                    'page_title'     => $title->getDBkey() ) );
 153         }
 154
 155         /**
 156          * Load the revision for the given title with the given timestamp.
 157          * WARNING: Timestamps may in some circumstances not be unique,
 158          * so this isn't the best key to use.
 159          *
 160          * @param $db DatabaseBase
 161          * @param $title Title
 162          * @param $timestamp String
 163          * @return Revision or null
 164          */
 165         public static function loadFromTimestamp( $db, $title, $timestamp ) {
 166                 return Revision::loadFromConds(
 167                         $db,
 168                         array( 'rev_timestamp'  => $db->timestamp( $timestamp ),
 169                                    'page_id=rev_page',
 170                                    'page_namespace' => $title->getNamespace(),
 171                                    'page_title'     => $title->getDBkey() ) );
 172         }
 173
 174         /**
 175          * Given a set of conditions, fetch a revision.
 176          *
 177          * @param $conditions Array
 178          * @return Revision or null
 179          */
 180         public static function newFromConds( $conditions ) {
 181                 $db = wfGetDB( DB_SLAVE );
 182                 $row = Revision::loadFromConds( $db, $conditions );
 183                 if( is_null( $row ) && wfGetLB()->getServerCount() > 1 ) {
 184                         $dbw = wfGetDB( DB_MASTER );
 185                         $row = Revision::loadFromConds( $dbw, $conditions );
 186                 }
 187                 return $row;
 188         }
 189
 190         /**
 191          * Given a set of conditions, fetch a revision from
 192          * the given database connection.
 193          *
 194          * @param $db DatabaseBase
 195          * @param $conditions Array
 196          * @return Revision or null
 197          */
 198         private static function loadFromConds( $db, $conditions ) {
 199                 $res = Revision::fetchFromConds( $db, $conditions );
 200                 if( $res ) {
 201                         $row = $res->fetchObject();
 202                         $res->free();
 203                         if( $row ) {
 204                                 $ret = new Revision( $row );
 205                                 return $ret;
 206                         }
 207                 }
 208                 $ret = null;
 209                 return $ret;
 210         }
 211
 212         /**
 213          * Return a wrapper for a series of database rows to
 214          * fetch all of a given page's revisions in turn.
 215          * Each row can be fed to the constructor to get objects.
 216          *
 217          * @param $title Title
 218          * @return ResultWrapper
 219          */
 220         public static function fetchRevision( $title ) {
 221                 return Revision::fetchFromConds(
 222                         wfGetDB( DB_SLAVE ),
 223                         array( 'rev_id=page_latest',
 224                                    'page_namespace' => $title->getNamespace(),
 225                                    'page_title'     => $title->getDBkey(),
 226                                    'page_id=rev_page' ) );
 227         }
 228
 229         /**
 230          * Given a set of conditions, return a ResultWrapper
 231          * which will return matching database rows with the
 232          * fields necessary to build Revision objects.
 233          *
 234          * @param $db DatabaseBase
 235          * @param $conditions Array
 236          * @return ResultWrapper
 237          */
 238         private static function fetchFromConds( $db, $conditions ) {
 239                 $fields = self::selectFields();
 240                 $fields[] = 'page_namespace';
 241                 $fields[] = 'page_title';
 242                 $fields[] = 'page_latest';
 243                 $res = $db->select(
 244                         array( 'page', 'revision' ),
 245                         $fields,
 246                         $conditions,
 247                         __METHOD__,
 248                         array( 'LIMIT' => 1 ) );
 249                 $ret = $db->resultObject( $res );
 250                 return $ret;
 251         }
 252
 253         /**
 254          * Return the list of revision fields that should be selected to create
 255          * a new revision.
 256          */
 257         public static function selectFields() {
 258                 return array(
 259                         'rev_id',
 260                         'rev_page',
 261                         'rev_text_id',
 262                         'rev_timestamp',
 263                         'rev_comment',
 264                         'rev_user_text,'.
 265                         'rev_user',
 266                         'rev_minor_edit',
 267                         'rev_deleted',
 268                         'rev_len',
 269                         'rev_parent_id'
 270                 );
 271         }
 272
 273         /**
 274          * Return the list of text fields that should be selected to read the
 275          * revision text
 276          */
 277         static function selectTextFields() {
 278                 return array(
 279                         'old_text',
 280                         'old_flags'
 281                 );
 282         }
 283
 284         /**
 285          * Return the list of page fields that should be selected from page table
 286          */
 287         static function selectPageFields() {
 288                 return array(
 289                         'page_namespace',
 290                         'page_title',
 291                         'page_latest'
 292                 );
 293         }
 294
 295         /**
 296          * Constructor
 297          *
 298          * @param $row Mixed: either a database row or an array
 299          * @access private
 300          */
 301         function __construct( $row ) {
 302                 if( is_object( $row ) ) {
 303                         $this->mId        = intval( $row->rev_id );
 304                         $this->mPage      = intval( $row->rev_page );
 305                         $this->mTextId    = intval( $row->rev_text_id );
 306                         $this->mComment   =         $row->rev_comment;
 307                         $this->mUserText  =         $row->rev_user_text;
 308                         $this->mUser      = intval( $row->rev_user );
 309                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 310                         $this->mTimestamp =         $row->rev_timestamp;
 311                         $this->mDeleted   = intval( $row->rev_deleted );
 312
 313                         if( !isset( $row->rev_parent_id ) )
 314                                 $this->mParentId = is_null($row->rev_parent_id) ? null : 0;
 315                         else
 316                                 $this->mParentId  = intval( $row->rev_parent_id );
 317
 318                         if( !isset( $row->rev_len ) || is_null( $row->rev_len ) )
 319                                 $this->mSize = null;
 320                         else
 321                                 $this->mSize = intval( $row->rev_len );
 322
 323                         if( isset( $row->page_latest ) ) {
 324                                 $this->mCurrent = ( $row->rev_id == $row->page_latest );
 325                                 $this->mTitle = Title::newFromRow( $row );
 326                         } else {
 327                                 $this->mCurrent = false;
 328                                 $this->mTitle = null;
 329                         }
 330
 331                         // Lazy extraction...
 332                         $this->mText      = null;
 333                         if( isset( $row->old_text ) ) {
 334                                 $this->mTextRow = $row;
 335                         } else {
 336                                 // 'text' table row entry will be lazy-loaded
 337                                 $this->mTextRow = null;
 338                         }
 339                 } elseif( is_array( $row ) ) {
 340                         // Build a new revision to be saved...
 341                         global $wgUser;
 342
 343                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 344                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 345                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 346                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 347                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 348                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 349                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestamp( TS_MW );
 350                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 351                         $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
 352                         $this->mParentId  = isset( $row['parent_id']  ) ? intval( $row['parent_id']  ) : null;
 353
 354                         // Enforce spacing trimming on supplied text
 355                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 356                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 357                         $this->mTextRow   = null;
 358
 359                         $this->mTitle     = null; # Load on demand if needed
 360                         $this->mCurrent   = false;
 361                         # If we still have no len_size, see it we have the text to figure it out
 362                         if ( !$this->mSize )
 363                                 $this->mSize      = is_null( $this->mText ) ? null : strlen( $this->mText );
 364                 } else {
 365                         throw new MWException( 'Revision constructor passed invalid row format.' );
 366                 }
 367                 $this->mUnpatrolled = null;
 368         }
 369
 370         /**
 371          * Get revision ID
 372          *
 373          * @return Integer
 374          */
 375         public function getId() {
 376                 return $this->mId;
 377         }
 378
 379         /**
 380          * Get text row ID
 381          *
 382          * @return Integer
 383          */
 384         public function getTextId() {
 385                 return $this->mTextId;
 386         }
 387
 388         /**
 389          * Get parent revision ID (the original previous page revision)
 390          *
 391          * @return Integer
 392          */
 393         public function getParentId() {
 394                 return $this->mParentId;
 395         }
 396
 397         /**
 398          * Returns the length of the text in this revision, or null if unknown.
 399          *
 400          * @return Integer
 401          */
 402         public function getSize() {
 403                 return $this->mSize;
 404         }
 405
 406         /**
 407          * Returns the title of the page associated with this entry.
 408          *
 409          * @return Title
 410          */
 411         public function getTitle() {
 412                 if( isset( $this->mTitle ) ) {
 413                         return $this->mTitle;
 414                 }
 415                 $dbr = wfGetDB( DB_SLAVE );
 416                 $row = $dbr->selectRow(
 417                         array( 'page', 'revision' ),
 418                         array( 'page_namespace', 'page_title' ),
 419                         array( 'page_id=rev_page',
 420                                    'rev_id' => $this->mId ),
 421                         'Revision::getTitle' );
 422                 if( $row ) {
 423                         $this->mTitle = Title::makeTitle( $row->page_namespace,
 424                                                                                           $row->page_title );
 425                 }
 426                 return $this->mTitle;
 427         }
 428
 429         /**
 430          * Set the title of the revision
 431          *
 432          * @param $title Title
 433          */
 434         public function setTitle( $title ) {
 435                 $this->mTitle = $title;
 436         }
 437
 438         /**
 439          * Get the page ID
 440          *
 441          * @return Integer
 442          */
 443         public function getPage() {
 444                 return $this->mPage;
 445         }
 446
 447         /**
 448          * Fetch revision's user id if it's available to the specified audience.
 449          * If the specified audience does not have access to it, zero will be
 450          * returned.
 451          *
 452          * @param $audience Integer: one of:
 453          *      Revision::FOR_PUBLIC       to be displayed to all users
 454          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 455          *      Revision::RAW              get the ID regardless of permissions
 456          *
 457          *
 458          * @return Integer
 459          */
 460         public function getUser( $audience = self::FOR_PUBLIC ) {
 461                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 462                         return 0;
 463                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER ) ) {
 464                         return 0;
 465                 } else {
 466                         return $this->mUser;
 467                 }
 468         }
 469
 470         /**
 471          * Fetch revision's user id without regard for the current user's permissions
 472          *
 473          * @return String
 474          */
 475         public function getRawUser() {
 476                 return $this->mUser;
 477         }
 478
 479         /**
 480          * Fetch revision's username if it's available to the specified audience.
 481          * If the specified audience does not have access to the username, an
 482          * empty string will be returned.
 483          *
 484          * @param $audience Integer: one of:
 485          *      Revision::FOR_PUBLIC       to be displayed to all users
 486          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 487          *      Revision::RAW              get the text regardless of permissions
 488          *
 489          * @return string
 490          */
 491         public function getUserText( $audience = self::FOR_PUBLIC ) {
 492                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 493                         return '';
 494                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER ) ) {
 495                         return '';
 496                 } else {
 497                         return $this->mUserText;
 498                 }
 499         }
 500
 501         /**
 502          * Fetch revision's username without regard for view restrictions
 503          *
 504          * @return String
 505          */
 506         public function getRawUserText() {
 507                 return $this->mUserText;
 508         }
 509
 510         /**
 511          * Fetch revision comment if it's available to the specified audience.
 512          * If the specified audience does not have access to the comment, an
 513          * empty string will be returned.
 514          *
 515          * @param $audience Integer: one of:
 516          *      Revision::FOR_PUBLIC       to be displayed to all users
 517          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 518          *      Revision::RAW              get the text regardless of permissions
 519          *
 520          * @return String
 521          */
 522         function getComment( $audience = self::FOR_PUBLIC ) {
 523                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_COMMENT ) ) {
 524                         return '';
 525                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_COMMENT ) ) {
 526                         return '';
 527                 } else {
 528                         return $this->mComment;
 529                 }
 530         }
 531
 532         /**
 533          * Fetch revision comment without regard for the current user's permissions
 534          *
 535          * @return String
 536          */
 537         public function getRawComment() {
 538                 return $this->mComment;
 539         }
 540
 541         /**
 542          * @return Boolean
 543          */
 544         public function isMinor() {
 545                 return (bool)$this->mMinorEdit;
 546         }
 547
 548         /**
 549          * @return Integer rcid of the unpatrolled row, zero if there isn't one
 550          */
 551         public function isUnpatrolled() {
 552                 if( $this->mUnpatrolled !== null ) {
 553                         return $this->mUnpatrolled;
 554                 }
 555                 $dbr = wfGetDB( DB_SLAVE );
 556                 $this->mUnpatrolled = $dbr->selectField( 'recentchanges',
 557                         'rc_id',
 558                         array( // Add redundant user,timestamp condition so we can use the existing index
 559                                 'rc_user_text'  => $this->getRawUserText(),
 560                                 'rc_timestamp'  => $dbr->timestamp( $this->getTimestamp() ),
 561                                 'rc_this_oldid' => $this->getId(),
 562                                 'rc_patrolled'  => 0
 563                         ),
 564                         __METHOD__
 565                 );
 566                 return (int)$this->mUnpatrolled;
 567         }
 568
 569         /**
 570          * int $field one of DELETED_* bitfield constants
 571          *
 572          * @return Boolean
 573          */
 574         public function isDeleted( $field ) {
 575                 return ( $this->mDeleted & $field ) == $field;
 576         }
 577
 578         /**
 579          * Get the deletion bitfield of the revision
 580          */
 581         public function getVisibility() {
 582                 return (int)$this->mDeleted;
 583         }
 584
 585         /**
 586          * Fetch revision text if it's available to the specified audience.
 587          * If the specified audience does not have the ability to view this
 588          * revision, an empty string will be returned.
 589          *
 590          * @param $audience Integer: one of:
 591          *      Revision::FOR_PUBLIC       to be displayed to all users
 592          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 593          *      Revision::RAW              get the text regardless of permissions
 594          *
 595          * @return String
 596          */
 597         public function getText( $audience = self::FOR_PUBLIC ) {
 598                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_TEXT ) ) {
 599                         return '';
 600                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_TEXT ) ) {
 601                         return '';
 602                 } else {
 603                         return $this->getRawText();
 604                 }
 605         }
 606
 607         /**
 608          * Alias for getText(Revision::FOR_THIS_USER)
 609          *
 610          * @deprecated since 1.17
 611          * @return String
 612          */
 613         public function revText() {
 614                 wfDeprecated( __METHOD__ );
 615                 return $this->getText( self::FOR_THIS_USER );
 616         }
 617
 618         /**
 619          * Fetch revision text without regard for view restrictions
 620          *
 621          * @return String
 622          */
 623         public function getRawText() {
 624                 if( is_null( $this->mText ) ) {
 625                         // Revision text is immutable. Load on demand:
 626                         $this->mText = $this->loadText();
 627                 }
 628                 return $this->mText;
 629         }
 630
 631         /**
 632          * @return String
 633          */
 634         public function getTimestamp() {
 635                 return wfTimestamp( TS_MW, $this->mTimestamp );
 636         }
 637
 638         /**
 639          * @return Boolean
 640          */
 641         public function isCurrent() {
 642                 return $this->mCurrent;
 643         }
 644
 645         /**
 646          * Get previous revision for this title
 647          *
 648          * @return Revision or null
 649          */
 650         public function getPrevious() {
 651                 if( $this->getTitle() ) {
 652                         $prev = $this->getTitle()->getPreviousRevisionID( $this->getId() );
 653                         if( $prev ) {
 654                                 return Revision::newFromTitle( $this->getTitle(), $prev );
 655                         }
 656                 }
 657                 return null;
 658         }
 659
 660         /**
 661          * Get next revision for this title
 662          *
 663          * @return Revision or null
 664          */
 665         public function getNext() {
 666                 if( $this->getTitle() ) {
 667                         $next = $this->getTitle()->getNextRevisionID( $this->getId() );
 668                         if ( $next ) {
 669                                 return Revision::newFromTitle( $this->getTitle(), $next );
 670                         }
 671                 }
 672                 return null;
 673         }
 674
 675         /**
 676          * Get previous revision Id for this page_id
 677          * This is used to populate rev_parent_id on save
 678          *
 679          * @param $db DatabaseBase
 680          * @return Integer
 681          */
 682         private function getPreviousRevisionId( $db ) {
 683                 if( is_null( $this->mPage ) ) {
 684                         return 0;
 685                 }
 686                 # Use page_latest if ID is not given
 687                 if( !$this->mId ) {
 688                         $prevId = $db->selectField( 'page', 'page_latest',
 689                                 array( 'page_id' => $this->mPage ),
 690                                 __METHOD__ );
 691                 } else {
 692                         $prevId = $db->selectField( 'revision', 'rev_id',
 693                                 array( 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ),
 694                                 __METHOD__,
 695                                 array( 'ORDER BY' => 'rev_id DESC' ) );
 696                 }
 697                 return intval( $prevId );
 698         }
 699
 700         /**
 701           * Get revision text associated with an old or archive row
 702           * $row is usually an object from wfFetchRow(), both the flags and the text
 703           * field must be included
 704           *
 705           * @param $row Object: the text data
 706           * @param $prefix String: table prefix (default 'old_')
 707           * @return String: text the text requested or false on failure
 708           */
 709         public static function getRevisionText( $row, $prefix = 'old_' ) {
 710                 wfProfileIn( __METHOD__ );
 711
 712                 # Get data
 713                 $textField = $prefix . 'text';
 714                 $flagsField = $prefix . 'flags';
 715
 716                 if( isset( $row->$flagsField ) ) {
 717                         $flags = explode( ',', $row->$flagsField );
 718                 } else {
 719                         $flags = array();
 720                 }
 721
 722                 if( isset( $row->$textField ) ) {
 723                         $text = $row->$textField;
 724                 } else {
 725                         wfProfileOut( __METHOD__ );
 726                         return false;
 727                 }
 728
 729                 # Use external methods for external objects, text in table is URL-only then
 730                 if ( in_array( 'external', $flags ) ) {
 731                         $url = $text;
 732                         @list(/* $proto */, $path ) = explode( '://', $url, 2 );
 733                         if( $path == '' ) {
 734                                 wfProfileOut( __METHOD__ );
 735                                 return false;
 736                         }
 737                         $text = ExternalStore::fetchFromURL( $url );
 738                 }
 739
 740                 // If the text was fetched without an error, convert it
 741                 if ( $text !== false ) {
 742                         if( in_array( 'gzip', $flags ) ) {
 743                                 # Deal with optional compression of archived pages.
 744                                 # This can be done periodically via maintenance/compressOld.php, and
 745                                 # as pages are saved if $wgCompressRevisions is set.
 746                                 $text = gzinflate( $text );
 747                         }
 748
 749                         if( in_array( 'object', $flags ) ) {
 750                                 # Generic compressed storage
 751                                 $obj = unserialize( $text );
 752                                 if ( !is_object( $obj ) ) {
 753                                         // Invalid object
 754                                         wfProfileOut( __METHOD__ );
 755                                         return false;
 756                                 }
 757                                 $text = $obj->getText();
 758                         }
 759
 760                         global $wgLegacyEncoding;
 761                         if( $text !== false && $wgLegacyEncoding
 762                                 && !in_array( 'utf-8', $flags ) && !in_array( 'utf8', $flags ) )
 763                         {
 764                                 # Old revisions kept around in a legacy encoding?
 765                                 # Upconvert on demand.
 766                                 # ("utf8" checked for compatibility with some broken
 767                                 #  conversion scripts 2008-12-30)
 768                                 global $wgContLang;
 769                                 $text = $wgContLang->iconv( $wgLegacyEncoding, 'UTF-8', $text );
 770                         }
 771                 }
 772                 wfProfileOut( __METHOD__ );
 773                 return $text;
 774         }
 775
 776         /**
 777          * If $wgCompressRevisions is enabled, we will compress data.
 778          * The input string is modified in place.
 779          * Return value is the flags field: contains 'gzip' if the
 780          * data is compressed, and 'utf-8' if we're saving in UTF-8
 781          * mode.
 782          *
 783          * @param $text Mixed: reference to a text
 784          * @return String
 785          */
 786         public static function compressRevisionText( &$text ) {
 787                 global $wgCompressRevisions;
 788                 $flags = array();
 789
 790                 # Revisions not marked this way will be converted
 791                 # on load if $wgLegacyCharset is set in the future.
 792                 $flags[] = 'utf-8';
 793
 794                 if( $wgCompressRevisions ) {
 795                         if( function_exists( 'gzdeflate' ) ) {
 796                                 $text = gzdeflate( $text );
 797                                 $flags[] = 'gzip';
 798                         } else {
 799                                 wfDebug( "Revision::compressRevisionText() -- no zlib support, not compressing\n" );
 800                         }
 801                 }
 802                 return implode( ',', $flags );
 803         }
 804
 805         /**
 806          * Insert a new revision into the database, returning the new revision ID
 807          * number on success and dies horribly on failure.
 808          *
 809          * @param $dbw DatabaseBase: (master connection)
 810          * @return Integer
 811          */
 812         public function insertOn( $dbw ) {
 813                 global $wgDefaultExternalStore;
 814
 815                 wfProfileIn( __METHOD__ );
 816
 817                 $data = $this->mText;
 818                 $flags = Revision::compressRevisionText( $data );
 819
 820                 # Write to external storage if required
 821                 if( $wgDefaultExternalStore ) {
 822                         // Store and get the URL
 823                         $data = ExternalStore::insertToDefault( $data );
 824                         if( !$data ) {
 825                                 throw new MWException( "Unable to store text to external storage" );
 826                         }
 827                         if( $flags ) {
 828                                 $flags .= ',';
 829                         }
 830                         $flags .= 'external';
 831                 }
 832
 833                 # Record the text (or external storage URL) to the text table
 834                 if( !isset( $this->mTextId ) ) {
 835                         $old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );
 836                         $dbw->insert( 'text',
 837                                 array(
 838                                         'old_id'    => $old_id,
 839                                         'old_text'  => $data,
 840                                         'old_flags' => $flags,
 841                                 ), __METHOD__
 842                         );
 843                         $this->mTextId = $dbw->insertId();
 844                 }
 845
 846                 if ( $this->mComment === null ) $this->mComment = "";
 847
 848                 # Record the edit in revisions
 849                 $rev_id = isset( $this->mId )
 850                         ? $this->mId
 851                         : $dbw->nextSequenceValue( 'revision_rev_id_seq' );
 852                 $dbw->insert( 'revision',
 853                         array(
 854                                 'rev_id'         => $rev_id,
 855                                 'rev_page'       => $this->mPage,
 856                                 'rev_text_id'    => $this->mTextId,
 857                                 'rev_comment'    => $this->mComment,
 858                                 'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
 859                                 'rev_user'       => $this->mUser,
 860                                 'rev_user_text'  => $this->mUserText,
 861                                 'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
 862                                 'rev_deleted'    => $this->mDeleted,
 863                                 'rev_len'        => $this->mSize,
 864                                 'rev_parent_id'  => is_null($this->mParentId) ?
 865                                         $this->getPreviousRevisionId( $dbw ) : $this->mParentId
 866                         ), __METHOD__
 867                 );
 868
 869                 $this->mId = !is_null( $rev_id ) ? $rev_id : $dbw->insertId();
 870
 871                 wfRunHooks( 'RevisionInsertComplete', array( &$this, $data, $flags ) );
 872
 873                 wfProfileOut( __METHOD__ );
 874                 return $this->mId;
 875         }
 876
 877         /**
 878          * Lazy-load the revision's text.
 879          * Currently hardcoded to the 'text' table storage engine.
 880          *
 881          * @return String
 882          */
 883         protected function loadText() {
 884                 wfProfileIn( __METHOD__ );
 885
 886                 // Caching may be beneficial for massive use of external storage
 887                 global $wgRevisionCacheExpiry, $wgMemc;
 888                 $textId = $this->getTextId();
 889                 $key = wfMemcKey( 'revisiontext', 'textid', $textId );
 890                 if( $wgRevisionCacheExpiry ) {
 891                         $text = $wgMemc->get( $key );
 892                         if( is_string( $text ) ) {
 893                                 wfDebug( __METHOD__ . ": got id $textId from cache\n" );
 894                                 wfProfileOut( __METHOD__ );
 895                                 return $text;
 896                         }
 897                 }
 898
 899                 // If we kept data for lazy extraction, use it now...
 900                 if ( isset( $this->mTextRow ) ) {
 901                         $row = $this->mTextRow;
 902                         $this->mTextRow = null;
 903                 } else {
 904                         $row = null;
 905                 }
 906
 907                 if( !$row ) {
 908                         // Text data is immutable; check slaves first.
 909                         $dbr = wfGetDB( DB_SLAVE );
 910                         $row = $dbr->selectRow( 'text',
 911                                 array( 'old_text', 'old_flags' ),
 912                                 array( 'old_id' => $this->getTextId() ),
 913                                 __METHOD__ );
 914                 }
 915
 916                 if( !$row && wfGetLB()->getServerCount() > 1 ) {
 917                         // Possible slave lag!
 918                         $dbw = wfGetDB( DB_MASTER );
 919                         $row = $dbw->selectRow( 'text',
 920                                 array( 'old_text', 'old_flags' ),
 921                                 array( 'old_id' => $this->getTextId() ),
 922                                 __METHOD__ );
 923                 }
 924
 925                 $text = self::getRevisionText( $row );
 926
 927                 # No negative caching -- negative hits on text rows may be due to corrupted slave servers
 928                 if( $wgRevisionCacheExpiry && $text !== false ) {
 929                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
 930                 }
 931
 932                 wfProfileOut( __METHOD__ );
 933
 934                 return $text;
 935         }
 936
 937         /**
 938          * Create a new null-revision for insertion into a page's
 939          * history. This will not re-save the text, but simply refer
 940          * to the text from the previous version.
 941          *
 942          * Such revisions can for instance identify page rename
 943          * operations and other such meta-modifications.
 944          *
 945          * @param $dbw DatabaseBase
 946          * @param $pageId Integer: ID number of the page to read from
 947          * @param $summary String: revision's summary
 948          * @param $minor Boolean: whether the revision should be considered as minor
 949          * @return Revision|null on error
 950          */
 951         public static function newNullRevision( $dbw, $pageId, $summary, $minor ) {
 952                 wfProfileIn( __METHOD__ );
 953
 954                 $current = $dbw->selectRow(
 955                         array( 'page', 'revision' ),
 956                         array( 'page_latest', 'rev_text_id', 'rev_len' ),
 957                         array(
 958                                 'page_id' => $pageId,
 959                                 'page_latest=rev_id',
 960                                 ),
 961                         __METHOD__ );
 962
 963                 if( $current ) {
 964                         $revision = new Revision( array(
 965                                 'page'       => $pageId,
 966                                 'comment'    => $summary,
 967                                 'minor_edit' => $minor,
 968                                 'text_id'    => $current->rev_text_id,
 969                                 'parent_id'  => $current->page_latest,
 970                                 'len'        => $current->rev_len
 971                                 ) );
 972                 } else {
 973                         $revision = null;
 974                 }
 975
 976                 wfProfileOut( __METHOD__ );
 977                 return $revision;
 978         }
 979
 980         /**
 981          * Determine if the current user is allowed to view a particular
 982          * field of this revision, if it's marked as deleted.
 983          *
 984          * @param $field Integer:one of self::DELETED_TEXT,
 985          *                              self::DELETED_COMMENT,
 986          *                              self::DELETED_USER
 987          * @return Boolean
 988          */
 989         public function userCan( $field ) {
 990                 return self::userCanBitfield( $this->mDeleted, $field );
 991         }
 992
 993         /**
 994          * Determine if the current user is allowed to view a particular
 995          * field of this revision, if it's marked as deleted. This is used
 996          * by various classes to avoid duplication.
 997          *
 998          * @param $bitfield Integer: current field
 999          * @param $field Integer: one of self::DELETED_TEXT = File::DELETED_FILE,
1000          *                               self::DELETED_COMMENT = File::DELETED_COMMENT,
1001          *                               self::DELETED_USER = File::DELETED_USER
1002          * @return Boolean
1003          */
1004         public static function userCanBitfield( $bitfield, $field ) {
1005                 if( $bitfield & $field ) { // aspect is deleted
1006                         global $wgUser;
1007                         if ( $bitfield & self::DELETED_RESTRICTED ) {
1008                                 $permission = 'suppressrevision';
1009                         } elseif ( $field & self::DELETED_TEXT ) {
1010                                 $permission = 'deletedtext';
1011                         } else {
1012                                 $permission = 'deletedhistory';
1013                         }
1014                         wfDebug( "Checking for $permission due to $field match on $bitfield\n" );
1015                         return $wgUser->isAllowed( $permission );
1016                 } else {
1017                         return true;
1018                 }
1019         }
1020
1021         /**
1022          * Get rev_timestamp from rev_id, without loading the rest of the row
1023          *
1024          * @param $title Title
1025          * @param $id Integer
1026          * @return String
1027          */
1028         static function getTimestampFromId( $title, $id ) {
1029                 $dbr = wfGetDB( DB_SLAVE );
1030                 // Casting fix for DB2
1031                 if ( $id == '' ) {
1032                         $id = 0;
1033                 }
1034                 $conds = array( 'rev_id' => $id );
1035                 $conds['rev_page'] = $title->getArticleId();
1036                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1037                 if ( $timestamp === false && wfGetLB()->getServerCount() > 1 ) {
1038                         # Not in slave, try master
1039                         $dbw = wfGetDB( DB_MASTER );
1040                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1041                 }
1042                 return wfTimestamp( TS_MW, $timestamp );
1043         }
1044
1045         /**
1046          * Get count of revisions per page...not very efficient
1047          *
1048          * @param $db DatabaseBase
1049          * @param $id Integer: page id
1050          * @return Integer
1051          */
1052         static function countByPageId( $db, $id ) {
1053                 $row = $db->selectRow( 'revision', 'COUNT(*) AS revCount',
1054                         array( 'rev_page' => $id ), __METHOD__ );
1055                 if( $row ) {
1056                         return $row->revCount;
1057                 }
1058                 return 0;
1059         }
1060
1061         /**
1062          * Get count of revisions per page...not very efficient
1063          *
1064          * @param $db DatabaseBase
1065          * @param $title Title
1066          * @return Integer
1067          */
1068         static function countByTitle( $db, $title ) {
1069                 $id = $title->getArticleId();
1070                 if( $id ) {
1071                         return Revision::countByPageId( $db, $id );
1072                 }
1073                 return 0;
1074         }
1075 }
1076
1077 /**
1078  * Aliases for backwards compatibility with 1.6
1079  */
1080 define( 'MW_REV_DELETED_TEXT', Revision::DELETED_TEXT );
1081 define( 'MW_REV_DELETED_COMMENT', Revision::DELETED_COMMENT );
1082 define( 'MW_REV_DELETED_USER', Revision::DELETED_USER );
1083 define( 'MW_REV_DELETED_RESTRICTED', Revision::DELETED_RESTRICTED );