includes/Revision.php

   1 <?php
   2 /**
   3  * Representation of a page version.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 /**
  24  * @todo document
  25  */
  26 class Revision {
  27         protected $mId;
  28         protected $mPage;
  29         protected $mUserText;
  30         protected $mOrigUserText;
  31         protected $mUser;
  32         protected $mMinorEdit;
  33         protected $mTimestamp;
  34         protected $mDeleted;
  35         protected $mSize;
  36         protected $mSha1;
  37         protected $mParentId;
  38         protected $mComment;
  39         protected $mText;
  40         protected $mTextRow;
  41         protected $mTitle;
  42         protected $mCurrent;
  43         protected $mContentModel;
  44         protected $mContentFormat;
  45         protected $mContent;
  46         protected $mContentHandler;
  47
  48         const DELETED_TEXT = 1;
  49         const DELETED_COMMENT = 2;
  50         const DELETED_USER = 4;
  51         const DELETED_RESTRICTED = 8;
  52         // Convenience field
  53         const SUPPRESSED_USER = 12;
  54         // Audience options for Revision::getText()
  55         const FOR_PUBLIC = 1;
  56         const FOR_THIS_USER = 2;
  57         const RAW = 3;
  58
  59         /**
  60          * Load a page revision from a given revision ID number.
  61          * Returns null if no such revision can be found.
  62          *
  63          * @param $id Integer
  64          * @return Revision or null
  65          */
  66         public static function newFromId( $id ) {
  67                 return Revision::newFromConds( array( 'rev_id' => intval( $id ) ) );
  68         }
  69
  70         /**
  71          * Load either the current, or a specified, revision
  72          * that's attached to a given title. If not attached
  73          * to that title, will return null.
  74          *
  75          * @param $title Title
  76          * @param $id Integer (optional)
  77          * @return Revision or null
  78          */
  79         public static function newFromTitle( $title, $id = 0 ) {
  80                 $conds = array(
  81                         'page_namespace' => $title->getNamespace(),
  82                         'page_title'     => $title->getDBkey()
  83                 );
  84                 if ( $id ) {
  85                         // Use the specified ID
  86                         $conds['rev_id'] = $id;
  87                 } elseif ( wfGetLB()->getServerCount() > 1 ) {
  88                         // Get the latest revision ID from the master
  89                         $dbw = wfGetDB( DB_MASTER );
  90                         $latest = $dbw->selectField( 'page', 'page_latest', $conds, __METHOD__ );
  91                         if ( $latest === false ) {
  92                                 return null; // page does not exist
  93                         }
  94                         $conds['rev_id'] = $latest;
  95                 } else {
  96                         // Use a join to get the latest revision
  97                         $conds[] = 'rev_id=page_latest';
  98                 }
  99                 return Revision::newFromConds( $conds );
 100         }
 101
 102         /**
 103          * Load either the current, or a specified, revision
 104          * that's attached to a given page ID.
 105          * Returns null if no such revision can be found.
 106          *
 107          * @param $revId Integer
 108          * @param $pageId Integer (optional)
 109          * @return Revision or null
 110          */
 111         public static function newFromPageId( $pageId, $revId = 0 ) {
 112                 $conds = array( 'page_id' => $pageId );
 113                 if ( $revId ) {
 114                         $conds['rev_id'] = $revId;
 115                 } elseif ( wfGetLB()->getServerCount() > 1 ) {
 116                         // Get the latest revision ID from the master
 117                         $dbw = wfGetDB( DB_MASTER );
 118                         $latest = $dbw->selectField( 'page', 'page_latest', $conds, __METHOD__ );
 119                         if ( $latest === false ) {
 120                                 return null; // page does not exist
 121                         }
 122                         $conds['rev_id'] = $latest;
 123                 } else {
 124                         $conds[] = 'rev_id = page_latest';
 125                 }
 126                 return Revision::newFromConds( $conds );
 127         }
 128
 129         /**
 130          * Make a fake revision object from an archive table row. This is queried
 131          * for permissions or even inserted (as in Special:Undelete)
 132          * @todo FIXME: Should be a subclass for RevisionDelete. [TS]
 133          *
 134          * @param $row
 135          * @param $overrides array
 136          *
 137          * @return Revision
 138          */
 139         public static function newFromArchiveRow( $row, $overrides = array() ) {
 140                 global $wgContentHandlerUseDB;
 141
 142                 $attribs = $overrides + array(
 143                         'page'       => isset( $row->ar_page_id ) ? $row->ar_page_id : null,
 144                         'id'         => isset( $row->ar_rev_id ) ? $row->ar_rev_id : null,
 145                         'comment'    => $row->ar_comment,
 146                         'user'       => $row->ar_user,
 147                         'user_text'  => $row->ar_user_text,
 148                         'timestamp'  => $row->ar_timestamp,
 149                         'minor_edit' => $row->ar_minor_edit,
 150                         'text_id'    => isset( $row->ar_text_id ) ? $row->ar_text_id : null,
 151                         'deleted'    => $row->ar_deleted,
 152                         'len'        => $row->ar_len,
 153                         'sha1'       => isset( $row->ar_sha1 ) ? $row->ar_sha1 : null,
 154                         'content_model' => isset( $row->ar_content_model ) ? $row->ar_content_model : null,
 155                         'content_format'  => isset( $row->ar_content_format ) ? $row->ar_content_format : null,
 156                 );
 157
 158                 if ( !$wgContentHandlerUseDB ) {
 159                         unset( $attribs['content_model'] );
 160                         unset( $attribs['content_format'] );
 161                 }
 162
 163                 if ( isset( $row->ar_text ) && !$row->ar_text_id ) {
 164                         // Pre-1.5 ar_text row
 165                         $attribs['text'] = self::getRevisionText( $row, 'ar_' );
 166                         if ( $attribs['text'] === false ) {
 167                                 throw new MWException( 'Unable to load text from archive row (possibly bug 22624)' );
 168                         }
 169                 }
 170                 return new self( $attribs );
 171         }
 172
 173         /**
 174          * @since 1.19
 175          *
 176          * @param $row
 177          * @return Revision
 178          */
 179         public static function newFromRow( $row ) {
 180                 return new self( $row );
 181         }
 182
 183         /**
 184          * Load a page revision from a given revision ID number.
 185          * Returns null if no such revision can be found.
 186          *
 187          * @param $db DatabaseBase
 188          * @param $id Integer
 189          * @return Revision or null
 190          */
 191         public static function loadFromId( $db, $id ) {
 192                 return Revision::loadFromConds( $db, array( 'rev_id' => intval( $id ) ) );
 193         }
 194
 195         /**
 196          * Load either the current, or a specified, revision
 197          * that's attached to a given page. If not attached
 198          * to that page, will return null.
 199          *
 200          * @param $db DatabaseBase
 201          * @param $pageid Integer
 202          * @param $id Integer
 203          * @return Revision or null
 204          */
 205         public static function loadFromPageId( $db, $pageid, $id = 0 ) {
 206                 $conds = array( 'rev_page' => intval( $pageid ), 'page_id'  => intval( $pageid ) );
 207                 if( $id ) {
 208                         $conds['rev_id'] = intval( $id );
 209                 } else {
 210                         $conds[] = 'rev_id=page_latest';
 211                 }
 212                 return Revision::loadFromConds( $db, $conds );
 213         }
 214
 215         /**
 216          * Load either the current, or a specified, revision
 217          * that's attached to a given page. If not attached
 218          * to that page, will return null.
 219          *
 220          * @param $db DatabaseBase
 221          * @param $title Title
 222          * @param $id Integer
 223          * @return Revision or null
 224          */
 225         public static function loadFromTitle( $db, $title, $id = 0 ) {
 226                 if( $id ) {
 227                         $matchId = intval( $id );
 228                 } else {
 229                         $matchId = 'page_latest';
 230                 }
 231                 return Revision::loadFromConds( $db,
 232                         array( "rev_id=$matchId",
 233                                    'page_namespace' => $title->getNamespace(),
 234                                    'page_title'     => $title->getDBkey() )
 235                 );
 236         }
 237
 238         /**
 239          * Load the revision for the given title with the given timestamp.
 240          * WARNING: Timestamps may in some circumstances not be unique,
 241          * so this isn't the best key to use.
 242          *
 243          * @param $db DatabaseBase
 244          * @param $title Title
 245          * @param $timestamp String
 246          * @return Revision or null
 247          */
 248         public static function loadFromTimestamp( $db, $title, $timestamp ) {
 249                 return Revision::loadFromConds( $db,
 250                         array( 'rev_timestamp'  => $db->timestamp( $timestamp ),
 251                                    'page_namespace' => $title->getNamespace(),
 252                                    'page_title'     => $title->getDBkey() )
 253                 );
 254         }
 255
 256         /**
 257          * Given a set of conditions, fetch a revision.
 258          *
 259          * @param $conditions Array
 260          * @return Revision or null
 261          */
 262         public static function newFromConds( $conditions ) {
 263                 $db = wfGetDB( DB_SLAVE );
 264                 $rev = Revision::loadFromConds( $db, $conditions );
 265                 if( is_null( $rev ) && wfGetLB()->getServerCount() > 1 ) {
 266                         $dbw = wfGetDB( DB_MASTER );
 267                         $rev = Revision::loadFromConds( $dbw, $conditions );
 268                 }
 269                 return $rev;
 270         }
 271
 272         /**
 273          * Given a set of conditions, fetch a revision from
 274          * the given database connection.
 275          *
 276          * @param $db DatabaseBase
 277          * @param $conditions Array
 278          * @return Revision or null
 279          */
 280         private static function loadFromConds( $db, $conditions ) {
 281                 $res = Revision::fetchFromConds( $db, $conditions );
 282                 if( $res ) {
 283                         $row = $res->fetchObject();
 284                         if( $row ) {
 285                                 $ret = new Revision( $row );
 286                                 return $ret;
 287                         }
 288                 }
 289                 $ret = null;
 290                 return $ret;
 291         }
 292
 293         /**
 294          * Return a wrapper for a series of database rows to
 295          * fetch all of a given page's revisions in turn.
 296          * Each row can be fed to the constructor to get objects.
 297          *
 298          * @param $title Title
 299          * @return ResultWrapper
 300          */
 301         public static function fetchRevision( $title ) {
 302                 return Revision::fetchFromConds(
 303                         wfGetDB( DB_SLAVE ),
 304                         array( 'rev_id=page_latest',
 305                                    'page_namespace' => $title->getNamespace(),
 306                                    'page_title'     => $title->getDBkey() )
 307                 );
 308         }
 309
 310         /**
 311          * Given a set of conditions, return a ResultWrapper
 312          * which will return matching database rows with the
 313          * fields necessary to build Revision objects.
 314          *
 315          * @param $db DatabaseBase
 316          * @param $conditions Array
 317          * @return ResultWrapper
 318          */
 319         private static function fetchFromConds( $db, $conditions ) {
 320                 $fields = array_merge(
 321                         self::selectFields(),
 322                         self::selectPageFields(),
 323                         self::selectUserFields()
 324                 );
 325                 return $db->select(
 326                         array( 'revision', 'page', 'user' ),
 327                         $fields,
 328                         $conditions,
 329                         __METHOD__,
 330                         array( 'LIMIT' => 1 ),
 331                         array( 'page' => self::pageJoinCond(), 'user' => self::userJoinCond() )
 332                 );
 333         }
 334
 335         /**
 336          * Return the value of a select() JOIN conds array for the user table.
 337          * This will get user table rows for logged-in users.
 338          * @since 1.19
 339          * @return Array
 340          */
 341         public static function userJoinCond() {
 342                 return array( 'LEFT JOIN', array( 'rev_user != 0', 'user_id = rev_user' ) );
 343         }
 344
 345         /**
 346          * Return the value of a select() page conds array for the paeg table.
 347          * This will assure that the revision(s) are not orphaned from live pages.
 348          * @since 1.19
 349          * @return Array
 350          */
 351         public static function pageJoinCond() {
 352                 return array( 'INNER JOIN', array( 'page_id = rev_page' ) );
 353         }
 354
 355         /**
 356          * Return the list of revision fields that should be selected to create
 357          * a new revision.
 358          * @return array
 359          */
 360         public static function selectFields() {
 361                 global $wgContentHandlerUseDB;
 362
 363                 $fields = array(
 364                         'rev_id',
 365                         'rev_page',
 366                         'rev_text_id',
 367                         'rev_timestamp',
 368                         'rev_comment',
 369                         'rev_user_text',
 370                         'rev_user',
 371                         'rev_minor_edit',
 372                         'rev_deleted',
 373                         'rev_len',
 374                         'rev_parent_id',
 375                         'rev_sha1',
 376                 );
 377
 378                 if ( $wgContentHandlerUseDB ) {
 379                         $fields[] = 'rev_content_format';
 380                         $fields[] = 'rev_content_model';
 381                 }
 382
 383                 return $fields;
 384         }
 385
 386         /**
 387          * Return the list of text fields that should be selected to read the
 388          * revision text
 389          * @return array
 390          */
 391         public static function selectTextFields() {
 392                 return array(
 393                         'old_text',
 394                         'old_flags'
 395                 );
 396         }
 397
 398         /**
 399          * Return the list of page fields that should be selected from page table
 400          * @return array
 401          */
 402         public static function selectPageFields() {
 403                 return array(
 404                         'page_namespace',
 405                         'page_title',
 406                         'page_id',
 407                         'page_latest'
 408                 );
 409         }
 410
 411         /**
 412          * Return the list of user fields that should be selected from user table
 413          * @return array
 414          */
 415         public static function selectUserFields() {
 416                 return array( 'user_name' );
 417         }
 418
 419         /**
 420          * Constructor
 421          *
 422          * @param $row Mixed: either a database row or an array
 423          * @access private
 424          */
 425         function __construct( $row ) {
 426                 if( is_object( $row ) ) {
 427                         $this->mId        = intval( $row->rev_id );
 428                         $this->mPage      = intval( $row->rev_page );
 429                         $this->mTextId    = intval( $row->rev_text_id );
 430                         $this->mComment   =         $row->rev_comment;
 431                         $this->mUser      = intval( $row->rev_user );
 432                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 433                         $this->mTimestamp =         $row->rev_timestamp;
 434                         $this->mDeleted   = intval( $row->rev_deleted );
 435
 436                         if( !isset( $row->rev_parent_id ) ) {
 437                                 $this->mParentId = is_null( $row->rev_parent_id ) ? null : 0;
 438                         } else {
 439                                 $this->mParentId  = intval( $row->rev_parent_id );
 440                         }
 441
 442                         if( !isset( $row->rev_len ) || is_null( $row->rev_len ) ) {
 443                                 $this->mSize = null;
 444                         } else {
 445                                 $this->mSize = intval( $row->rev_len );
 446                         }
 447
 448                         if ( !isset( $row->rev_sha1 ) ) {
 449                                 $this->mSha1 = null;
 450                         } else {
 451                                 $this->mSha1 = $row->rev_sha1;
 452                         }
 453
 454                         if( isset( $row->page_latest ) ) {
 455                                 $this->mCurrent = ( $row->rev_id == $row->page_latest );
 456                                 $this->mTitle = Title::newFromRow( $row );
 457                         } else {
 458                                 $this->mCurrent = false;
 459                                 $this->mTitle = null;
 460                         }
 461
 462                         if( !isset( $row->rev_content_model ) || is_null( $row->rev_content_model ) ) {
 463                                 $this->mContentModel = null; # determine on demand if needed
 464                         } else {
 465                                 $this->mContentModel = intval( $row->rev_content_model );
 466                         }
 467
 468                         if( !isset( $row->rev_content_format ) || is_null( $row->rev_content_format ) ) {
 469                                 $this->mContentFormat = null; # determine on demand if needed
 470                         } else {
 471                                 $this->mContentFormat = intval( $row->rev_content_format );
 472                         }
 473
 474                         // Lazy extraction...
 475                         $this->mText      = null;
 476                         if( isset( $row->old_text ) ) {
 477                                 $this->mTextRow = $row;
 478                         } else {
 479                                 // 'text' table row entry will be lazy-loaded
 480                                 $this->mTextRow = null;
 481                         }
 482
 483                         // Use user_name for users and rev_user_text for IPs...
 484                         $this->mUserText = null; // lazy load if left null
 485                         if ( $this->mUser == 0 ) {
 486                                 $this->mUserText = $row->rev_user_text; // IP user
 487                         } elseif ( isset( $row->user_name ) ) {
 488                                 $this->mUserText = $row->user_name; // logged-in user
 489                         }
 490                         $this->mOrigUserText = $row->rev_user_text;
 491                 } elseif( is_array( $row ) ) {
 492                         // Build a new revision to be saved...
 493                         global $wgUser; // ugh
 494
 495
 496                         # if we have a content object, use it to set the model and type
 497                         if ( !empty( $row['content'] ) ) {
 498                                 if ( !empty( $row['text_id'] ) ) { #FIXME: when is that set? test with external store setup! check out insertOn()
 499                                         throw new MWException( "Text already stored in external store (id {$row['text_id']}), can't serialize content object" );
 500                                 }
 501
 502                                 $row['content_model'] = $row['content']->getModel();
 503                                 # note: mContentFormat is initializes later accordingly
 504                                 # note: content is serialized later in this method!
 505                                 # also set text to null?
 506                         }
 507
 508                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 509                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 510                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 511                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 512                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 513                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 514                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestampNow();
 515                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 516                         $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
 517                         $this->mParentId  = isset( $row['parent_id']  ) ? intval( $row['parent_id']  ) : null;
 518                         $this->mSha1      = isset( $row['sha1']  )      ? strval( $row['sha1']  )      : null;
 519
 520                         $this->mContentModel = isset( $row['content_model']  )  ? intval( $row['content_model'] )  : null;
 521                         $this->mContentFormat    = isset( $row['content_format']  ) ? intval( $row['content_format'] ) : null;
 522
 523                         // Enforce spacing trimming on supplied text
 524                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 525                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 526                         $this->mTextRow   = null;
 527
 528                         # if we have a content object, override mText and mContentModel
 529                         if ( !empty( $row['content'] ) ) {
 530                                 $handler = $this->getContentHandler();
 531                                 $this->mContent = $row['content'];
 532
 533                                 $this->mContentModel = $this->mContent->getModel();
 534                                 $this->mContentHandler = null;
 535
 536                                 $this->mText = $handler->serializeContent( $row['content'], $this->getContentFormat() );
 537                         } elseif ( !is_null( $this->mText ) ) {
 538                                 $handler = $this->getContentHandler();
 539                                 $this->mContent = $handler->unserializeContent( $this->mText );
 540                         }
 541
 542                         $this->mTitle     = null; # Load on demand if needed
 543                         $this->mCurrent   = false; #XXX: really? we are about to create a revision. it will usually then be the current one.
 544
 545                         # If we still have no length, see it we have the text to figure it out
 546                         if ( !$this->mSize ) {
 547                                 if ( !is_null( $this->mContent ) ) {
 548                                         $this->mSize = $this->mContent->getSize();
 549                                 } else {
 550                                         #XXX: my be inconsistent with the notion of "size" use for the present content model
 551                                         #NOTE: should never happen if we have either text or content object!
 552                                         $this->mSize = is_null( $this->mText ) ? null : strlen( $this->mText );
 553                                 }
 554                         }
 555
 556                         # Same for sha1
 557                         if ( $this->mSha1 === null ) {
 558                                 $this->mSha1 = is_null( $this->mText ) ? null : self::base36Sha1( $this->mText );
 559                         }
 560
 561                         $this->getContentModel(); # force lazy init
 562                         $this->getContentFormat();    # force lazy init
 563                 } else {
 564                         throw new MWException( 'Revision constructor passed invalid row format.' );
 565                 }
 566                 $this->mUnpatrolled = null;
 567
 568                 // @TODO: add support for ar_content_format, ar_content_model, rev_content_format, rev_content_model to API
 569                 // @TODO: get rid of $mText
 570         }
 571
 572         /**
 573          * Get revision ID
 574          *
 575          * @return Integer
 576          */
 577         public function getId() {
 578                 return $this->mId;
 579         }
 580
 581         /**
 582          * Set the revision ID
 583          *
 584          * @since 1.19
 585          * @param $id Integer
 586          */
 587         public function setId( $id ) {
 588                 $this->mId = $id;
 589         }
 590
 591         /**
 592          * Get text row ID
 593          *
 594          * @return Integer
 595          */
 596         public function getTextId() {
 597                 return $this->mTextId;
 598         }
 599
 600         /**
 601          * Get parent revision ID (the original previous page revision)
 602          *
 603          * @return Integer|null
 604          */
 605         public function getParentId() {
 606                 return $this->mParentId;
 607         }
 608
 609         /**
 610          * Returns the length of the text in this revision, or null if unknown.
 611          *
 612          * @return Integer
 613          */
 614         public function getSize() {
 615                 return $this->mSize;
 616         }
 617
 618         /**
 619          * Returns the base36 sha1 of the text in this revision, or null if unknown.
 620          *
 621          * @return String
 622          */
 623         public function getSha1() {
 624                 return $this->mSha1;
 625         }
 626
 627         /**
 628          * Returns the title of the page associated with this entry.
 629          *
 630          * @return Title
 631          */
 632         public function getTitle() {
 633                 if( isset( $this->mTitle ) ) {
 634                         return $this->mTitle;
 635                 }
 636                 $dbr = wfGetDB( DB_SLAVE );
 637                 $row = $dbr->selectRow(
 638                         array( 'page', 'revision' ),
 639                         self::selectPageFields(),
 640                         array( 'page_id=rev_page',
 641                                    'rev_id' => $this->mId ),
 642                         __METHOD__ );
 643                 if ( $row ) {
 644                         $this->mTitle = Title::newFromRow( $row );
 645                 }
 646                 return $this->mTitle;
 647         }
 648
 649         /**
 650          * Set the title of the revision
 651          *
 652          * @param $title Title
 653          */
 654         public function setTitle( $title ) {
 655                 $this->mTitle = $title;
 656         }
 657
 658         /**
 659          * Get the page ID
 660          *
 661          * @return Integer
 662          */
 663         public function getPage() {
 664                 return $this->mPage;
 665         }
 666
 667         /**
 668          * Fetch revision's user id if it's available to the specified audience.
 669          * If the specified audience does not have access to it, zero will be
 670          * returned.
 671          *
 672          * @param $audience Integer: one of:
 673          *      Revision::FOR_PUBLIC       to be displayed to all users
 674          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 675          *      Revision::RAW              get the ID regardless of permissions
 676          * @param $user User object to check for, only if FOR_THIS_USER is passed
 677          *              to the $audience parameter
 678          * @return Integer
 679          */
 680         public function getUser( $audience = self::FOR_PUBLIC, User $user = null ) {
 681                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 682                         return 0;
 683                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
 684                         return 0;
 685                 } else {
 686                         return $this->mUser;
 687                 }
 688         }
 689
 690         /**
 691          * Fetch revision's user id without regard for the current user's permissions
 692          *
 693          * @return String
 694          */
 695         public function getRawUser() {
 696                 return $this->mUser;
 697         }
 698
 699         /**
 700          * Fetch revision's username if it's available to the specified audience.
 701          * If the specified audience does not have access to the username, an
 702          * empty string will be returned.
 703          *
 704          * @param $audience Integer: one of:
 705          *      Revision::FOR_PUBLIC       to be displayed to all users
 706          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 707          *      Revision::RAW              get the text regardless of permissions
 708          * @param $user User object to check for, only if FOR_THIS_USER is passed
 709          *              to the $audience parameter
 710          * @return string
 711          */
 712         public function getUserText( $audience = self::FOR_PUBLIC, User $user = null ) {
 713                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 714                         return '';
 715                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
 716                         return '';
 717                 } else {
 718                         return $this->getRawUserText();
 719                 }
 720         }
 721
 722         /**
 723          * Fetch revision's username without regard for view restrictions
 724          *
 725          * @return String
 726          */
 727         public function getRawUserText() {
 728                 if ( $this->mUserText === null ) {
 729                         $this->mUserText = User::whoIs( $this->mUser ); // load on demand
 730                         if ( $this->mUserText === false ) {
 731                                 # This shouldn't happen, but it can if the wiki was recovered
 732                                 # via importing revs and there is no user table entry yet.
 733                                 $this->mUserText = $this->mOrigUserText;
 734                         }
 735                 }
 736                 return $this->mUserText;
 737         }
 738
 739         /**
 740          * Fetch revision comment if it's available to the specified audience.
 741          * If the specified audience does not have access to the comment, an
 742          * empty string will be returned.
 743          *
 744          * @param $audience Integer: one of:
 745          *      Revision::FOR_PUBLIC       to be displayed to all users
 746          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 747          *      Revision::RAW              get the text regardless of permissions
 748          * @param $user User object to check for, only if FOR_THIS_USER is passed
 749          *              to the $audience parameter
 750          * @return String
 751          */
 752         function getComment( $audience = self::FOR_PUBLIC, User $user = null ) {
 753                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_COMMENT ) ) {
 754                         return '';
 755                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_COMMENT, $user ) ) {
 756                         return '';
 757                 } else {
 758                         return $this->mComment;
 759                 }
 760         }
 761
 762         /**
 763          * Fetch revision comment without regard for the current user's permissions
 764          *
 765          * @return String
 766          */
 767         public function getRawComment() {
 768                 return $this->mComment;
 769         }
 770
 771         /**
 772          * @return Boolean
 773          */
 774         public function isMinor() {
 775                 return (bool)$this->mMinorEdit;
 776         }
 777
 778         /**
 779          * @return Integer rcid of the unpatrolled row, zero if there isn't one
 780          */
 781         public function isUnpatrolled() {
 782                 if( $this->mUnpatrolled !== null ) {
 783                         return $this->mUnpatrolled;
 784                 }
 785                 $dbr = wfGetDB( DB_SLAVE );
 786                 $this->mUnpatrolled = $dbr->selectField( 'recentchanges',
 787                         'rc_id',
 788                         array( // Add redundant user,timestamp condition so we can use the existing index
 789                                 'rc_user_text'  => $this->getRawUserText(),
 790                                 'rc_timestamp'  => $dbr->timestamp( $this->getTimestamp() ),
 791                                 'rc_this_oldid' => $this->getId(),
 792                                 'rc_patrolled'  => 0
 793                         ),
 794                         __METHOD__
 795                 );
 796                 return (int)$this->mUnpatrolled;
 797         }
 798
 799         /**
 800          * @param $field int one of DELETED_* bitfield constants
 801          *
 802          * @return Boolean
 803          */
 804         public function isDeleted( $field ) {
 805                 return ( $this->mDeleted & $field ) == $field;
 806         }
 807
 808         /**
 809          * Get the deletion bitfield of the revision
 810          *
 811          * @return int
 812          */
 813         public function getVisibility() {
 814                 return (int)$this->mDeleted;
 815         }
 816
 817         /**
 818          * Fetch revision text if it's available to the specified audience.
 819          * If the specified audience does not have the ability to view this
 820          * revision, an empty string will be returned.
 821          *
 822          * @param $audience Integer: one of:
 823          *      Revision::FOR_PUBLIC       to be displayed to all users
 824          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 825          *      Revision::RAW              get the text regardless of permissions
 826          * @param $user User object to check for, only if FOR_THIS_USER is passed
 827          *              to the $audience parameter
 828          * @return String
 829          * @deprecated in 1.WD, use getContent() instead
 830          */
 831         public function getText( $audience = self::FOR_PUBLIC, User $user = null ) { #FIXME: deprecated, replace usage! #FIXME: used a LOT!
 832                 wfDeprecated( __METHOD__, '1.WD' );
 833
 834                 $content = $this->getContent();
 835                 return ContentHandler::getContentText( $content ); # returns the raw content text, if applicable
 836         }
 837
 838         /**
 839          * Fetch revision content if it's available to the specified audience.
 840          * If the specified audience does not have the ability to view this
 841          * revision, null will be returned.
 842          *
 843          * @param $audience Integer: one of:
 844          *      Revision::FOR_PUBLIC       to be displayed to all users
 845          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 846          *      Revision::RAW              get the text regardless of permissions
 847          * @param $user User object to check for, only if FOR_THIS_USER is passed
 848          *              to the $audience parameter
 849          * @return Content
 850          *
 851          * @since 1.WD
 852          */
 853         public function getContent( $audience = self::FOR_PUBLIC, User $user = null ) {
 854                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_TEXT ) ) {
 855                         return null;
 856                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_TEXT, $user ) ) {
 857                         return null;
 858                 } else {
 859                         return $this->getContentInternal();
 860                 }
 861         }
 862
 863         /**
 864          * Alias for getText(Revision::FOR_THIS_USER)
 865          *
 866          * @deprecated since 1.17
 867          * @return String
 868          */
 869         public function revText() {
 870                 wfDeprecated( __METHOD__, '1.17' );
 871                 return $this->getText( self::FOR_THIS_USER );
 872         }
 873
 874         /**
 875          * Fetch revision text without regard for view restrictions
 876          *
 877          * @return String
 878          */
 879         public function getRawText() { #FIXME: deprecated, replace usage!
 880                 return $this->getText( self::RAW );
 881         }
 882
 883         protected function getContentInternal() {
 884                 if( is_null( $this->mContent ) ) {
 885                         // Revision is immutable. Load on demand:
 886
 887                         $handler = $this->getContentHandler();
 888                         $format = $this->getContentFormat();
 889                         $title = $this->getTitle();
 890
 891                         if( is_null( $this->mText ) ) {
 892                                 // Load text on demand:
 893                                 $this->mText = $this->loadText();
 894                         }
 895
 896                         $this->mContent = is_null( $this->mText ) ? null : $handler->unserializeContent( $this->mText, $format );
 897                 }
 898
 899                 return $this->mContent;
 900         }
 901
 902         /**
 903          * Returns the content model for this revision.
 904          *
 905          * If no content model was stored in the database, $this->getTitle()->getContentModel() is
 906          * used to determine the content model to use. If no title is know, CONTENT_MODEL_WIKITEXT
 907          * is used as a last resort.
 908          *
 909          * @return int the content model id associated with this revision, see the CONTENT_MODEL_XXX constants.
 910          **/
 911         public function getContentModel() {
 912                 if ( !$this->mContentModel ) {
 913                         $title = $this->getTitle();
 914                         $this->mContentModel = ( $title ? $title->getContentModel() : CONTENT_MODEL_WIKITEXT );
 915
 916                         assert( !empty( $this->mContentModel ) );
 917                 }
 918
 919                 return $this->mContentModel;
 920         }
 921
 922         /**
 923          * Returns the content format for this revision.
 924          *
 925          * If no content format was stored in the database, the default format for this
 926          * revision's content model is returned.
 927          *
 928          * @return int the content format id associated with this revision, see the CONTENT_FORMAT_XXX constants.
 929          **/
 930         public function getContentFormat() {
 931                 if ( !$this->mContentFormat ) {
 932                         $handler = $this->getContentHandler();
 933                         $this->mContentFormat = $handler->getDefaultFormat();
 934
 935                         assert( !empty( $this->mContentFormat ) );
 936                 }
 937
 938                 return $this->mContentFormat;
 939         }
 940
 941         /**
 942          * Returns the content handler appropriate for this revision's content model.
 943          *
 944          * @return ContentHandler
 945          */
 946         public function getContentHandler() {
 947                 if ( !$this->mContentHandler ) {
 948                         $model = $this->getContentModel();
 949                         $this->mContentHandler = ContentHandler::getForModelID( $model );
 950
 951                         assert( $this->mContentHandler->isSupportedFormat( $this->getContentFormat() ) );
 952                 }
 953
 954                 return $this->mContentHandler;
 955         }
 956
 957         /**
 958          * @return String
 959          */
 960         public function getTimestamp() {
 961                 return wfTimestamp( TS_MW, $this->mTimestamp );
 962         }
 963
 964         /**
 965          * @return Boolean
 966          */
 967         public function isCurrent() {
 968                 return $this->mCurrent;
 969         }
 970
 971         /**
 972          * Get previous revision for this title
 973          *
 974          * @return Revision or null
 975          */
 976         public function getPrevious() {
 977                 if( $this->getTitle() ) {
 978                         $prev = $this->getTitle()->getPreviousRevisionID( $this->getId() );
 979                         if( $prev ) {
 980                                 return Revision::newFromTitle( $this->getTitle(), $prev );
 981                         }
 982                 }
 983                 return null;
 984         }
 985
 986         /**
 987          * Get next revision for this title
 988          *
 989          * @return Revision or null
 990          */
 991         public function getNext() {
 992                 if( $this->getTitle() ) {
 993                         $next = $this->getTitle()->getNextRevisionID( $this->getId() );
 994                         if ( $next ) {
 995                                 return Revision::newFromTitle( $this->getTitle(), $next );
 996                         }
 997                 }
 998                 return null;
 999         }
1000
1001         /**
1002          * Get previous revision Id for this page_id
1003          * This is used to populate rev_parent_id on save
1004          *
1005          * @param $db DatabaseBase
1006          * @return Integer
1007          */
1008         private function getPreviousRevisionId( $db ) {
1009                 if( is_null( $this->mPage ) ) {
1010                         return 0;
1011                 }
1012                 # Use page_latest if ID is not given
1013                 if( !$this->mId ) {
1014                         $prevId = $db->selectField( 'page', 'page_latest',
1015                                 array( 'page_id' => $this->mPage ),
1016                                 __METHOD__ );
1017                 } else {
1018                         $prevId = $db->selectField( 'revision', 'rev_id',
1019                                 array( 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ),
1020                                 __METHOD__,
1021                                 array( 'ORDER BY' => 'rev_id DESC' ) );
1022                 }
1023                 return intval( $prevId );
1024         }
1025
1026         /**
1027           * Get revision text associated with an old or archive row
1028           * $row is usually an object from wfFetchRow(), both the flags and the text
1029           * field must be included
1030           *
1031           * @param $row Object: the text data
1032           * @param $prefix String: table prefix (default 'old_')
1033           * @return String: text the text requested or false on failure
1034           */
1035         public static function getRevisionText( $row, $prefix = 'old_' ) {
1036                 wfProfileIn( __METHOD__ );
1037
1038                 # Get data
1039                 $textField = $prefix . 'text';
1040                 $flagsField = $prefix . 'flags';
1041
1042                 if( isset( $row->$flagsField ) ) {
1043                         $flags = explode( ',', $row->$flagsField );
1044                 } else {
1045                         $flags = array();
1046                 }
1047
1048                 if( isset( $row->$textField ) ) {
1049                         $text = $row->$textField;
1050                 } else {
1051                         wfProfileOut( __METHOD__ );
1052                         return false;
1053                 }
1054
1055                 # Use external methods for external objects, text in table is URL-only then
1056                 if ( in_array( 'external', $flags ) ) {
1057                         $url = $text;
1058                         $parts = explode( '://', $url, 2 );
1059                         if( count( $parts ) == 1 || $parts[1] == '' ) {
1060                                 wfProfileOut( __METHOD__ );
1061                                 return false;
1062                         }
1063                         $text = ExternalStore::fetchFromURL( $url );
1064                 }
1065
1066                 // If the text was fetched without an error, convert it
1067                 if ( $text !== false ) {
1068                         if( in_array( 'gzip', $flags ) ) {
1069                                 # Deal with optional compression of archived pages.
1070                                 # This can be done periodically via maintenance/compressOld.php, and
1071                                 # as pages are saved if $wgCompressRevisions is set.
1072                                 $text = gzinflate( $text );
1073                         }
1074
1075                         if( in_array( 'object', $flags ) ) {
1076                                 # Generic compressed storage
1077                                 $obj = unserialize( $text );
1078                                 if ( !is_object( $obj ) ) {
1079                                         // Invalid object
1080                                         wfProfileOut( __METHOD__ );
1081                                         return false;
1082                                 }
1083                                 $text = $obj->getText();
1084                         }
1085
1086                         global $wgLegacyEncoding;
1087                         if( $text !== false && $wgLegacyEncoding
1088                                 && !in_array( 'utf-8', $flags ) && !in_array( 'utf8', $flags ) )
1089                         {
1090                                 # Old revisions kept around in a legacy encoding?
1091                                 # Upconvert on demand.
1092                                 # ("utf8" checked for compatibility with some broken
1093                                 #  conversion scripts 2008-12-30)
1094                                 global $wgContLang;
1095                                 $text = $wgContLang->iconv( $wgLegacyEncoding, 'UTF-8', $text );
1096                         }
1097                 }
1098                 wfProfileOut( __METHOD__ );
1099                 return $text;
1100         }
1101
1102         /**
1103          * If $wgCompressRevisions is enabled, we will compress data.
1104          * The input string is modified in place.
1105          * Return value is the flags field: contains 'gzip' if the
1106          * data is compressed, and 'utf-8' if we're saving in UTF-8
1107          * mode.
1108          *
1109          * @param $text Mixed: reference to a text
1110          * @return String
1111          */
1112         public static function compressRevisionText( &$text ) {
1113                 global $wgCompressRevisions;
1114                 $flags = array();
1115
1116                 # Revisions not marked this way will be converted
1117                 # on load if $wgLegacyCharset is set in the future.
1118                 $flags[] = 'utf-8';
1119
1120                 if( $wgCompressRevisions ) {
1121                         if( function_exists( 'gzdeflate' ) ) {
1122                                 $text = gzdeflate( $text );
1123                                 $flags[] = 'gzip';
1124                         } else {
1125                                 wfDebug( "Revision::compressRevisionText() -- no zlib support, not compressing\n" );
1126                         }
1127                 }
1128                 return implode( ',', $flags );
1129         }
1130
1131         /**
1132          * Insert a new revision into the database, returning the new revision ID
1133          * number on success and dies horribly on failure.
1134          *
1135          * @param $dbw DatabaseBase: (master connection)
1136          * @return Integer
1137          */
1138         public function insertOn( $dbw ) {
1139                 global $wgDefaultExternalStore, $wgContentHandlerUseDB;
1140
1141                 wfProfileIn( __METHOD__ );
1142
1143                 $data = $this->mText;
1144                 $flags = Revision::compressRevisionText( $data );
1145
1146                 # Write to external storage if required
1147                 if( $wgDefaultExternalStore ) {
1148                         // Store and get the URL
1149                         $data = ExternalStore::insertToDefault( $data );
1150                         if( !$data ) {
1151                                 throw new MWException( "Unable to store text to external storage" );
1152                         }
1153                         if( $flags ) {
1154                                 $flags .= ',';
1155                         }
1156                         $flags .= 'external';
1157                 }
1158
1159                 # Record the text (or external storage URL) to the text table
1160                 if( !isset( $this->mTextId ) ) {
1161                         $old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );
1162                         $dbw->insert( 'text',
1163                                 array(
1164                                         'old_id'    => $old_id,
1165                                         'old_text'  => $data,
1166                                         'old_flags' => $flags,
1167                                 ), __METHOD__
1168                         );
1169                         $this->mTextId = $dbw->insertId();
1170                 }
1171
1172                 if ( $this->mComment === null ) $this->mComment = "";
1173
1174                 # Record the edit in revisions
1175                 $rev_id = isset( $this->mId )
1176                         ? $this->mId
1177                         : $dbw->nextSequenceValue( 'revision_rev_id_seq' );
1178
1179                 $row = array(
1180                         'rev_id'         => $rev_id,
1181                         'rev_page'       => $this->mPage,
1182                         'rev_text_id'    => $this->mTextId,
1183                         'rev_comment'    => $this->mComment,
1184                         'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
1185                         'rev_user'       => $this->mUser,
1186                         'rev_user_text'  => $this->mUserText,
1187                         'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
1188                         'rev_deleted'    => $this->mDeleted,
1189                         'rev_len'        => $this->mSize,
1190                         'rev_parent_id'  => is_null( $this->mParentId )
1191                                 ? $this->getPreviousRevisionId( $dbw )
1192                                 : $this->mParentId,
1193                         'rev_sha1'       => is_null( $this->mSha1 )
1194                                 ? Revision::base36Sha1( $this->mText )
1195                                 : $this->mSha1,
1196                 );
1197
1198                 if ( $wgContentHandlerUseDB ) {
1199                         $row[ 'rev_content_model' ] = $this->getContentModel();
1200                         $row[ 'rev_content_format' ] = $this->getContentFormat();
1201                 }
1202
1203                 $dbw->insert( 'revision', $row, __METHOD__ );
1204
1205                 $this->mId = !is_null( $rev_id ) ? $rev_id : $dbw->insertId();
1206
1207                 wfRunHooks( 'RevisionInsertComplete', array( &$this, $data, $flags ) );
1208
1209                 wfProfileOut( __METHOD__ );
1210                 return $this->mId;
1211         }
1212
1213         /**
1214          * Get the base 36 SHA-1 value for a string of text
1215          * @param $text String
1216          * @return String
1217          */
1218         public static function base36Sha1( $text ) {
1219                 return wfBaseConvert( sha1( $text ), 16, 36, 31 );
1220         }
1221
1222         /**
1223          * Lazy-load the revision's text.
1224          * Currently hardcoded to the 'text' table storage engine.
1225          *
1226          * @return String
1227          */
1228         protected function loadText() {
1229                 wfProfileIn( __METHOD__ );
1230
1231                 // Caching may be beneficial for massive use of external storage
1232                 global $wgRevisionCacheExpiry, $wgMemc;
1233                 $textId = $this->getTextId();
1234                 $key = wfMemcKey( 'revisiontext', 'textid', $textId );
1235                 if( $wgRevisionCacheExpiry ) {
1236                         $text = $wgMemc->get( $key );
1237                         if( is_string( $text ) ) {
1238                                 wfDebug( __METHOD__ . ": got id $textId from cache\n" );
1239                                 wfProfileOut( __METHOD__ );
1240                                 return $text;
1241                         }
1242                 }
1243
1244                 // If we kept data for lazy extraction, use it now...
1245                 if ( isset( $this->mTextRow ) ) {
1246                         $row = $this->mTextRow;
1247                         $this->mTextRow = null;
1248                 } else {
1249                         $row = null;
1250                 }
1251
1252                 if( !$row ) {
1253                         // Text data is immutable; check slaves first.
1254                         $dbr = wfGetDB( DB_SLAVE );
1255                         $row = $dbr->selectRow( 'text',
1256                                 array( 'old_text', 'old_flags' ),
1257                                 array( 'old_id' => $this->getTextId() ),
1258                                 __METHOD__ );
1259                 }
1260
1261                 if( !$row && wfGetLB()->getServerCount() > 1 ) {
1262                         // Possible slave lag!
1263                         $dbw = wfGetDB( DB_MASTER );
1264                         $row = $dbw->selectRow( 'text',
1265                                 array( 'old_text', 'old_flags' ),
1266                                 array( 'old_id' => $this->getTextId() ),
1267                                 __METHOD__ );
1268                 }
1269
1270                 $text = self::getRevisionText( $row );
1271
1272                 # No negative caching -- negative hits on text rows may be due to corrupted slave servers
1273                 if( $wgRevisionCacheExpiry && $text !== false ) {
1274                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
1275                 }
1276
1277                 wfProfileOut( __METHOD__ );
1278
1279                 return $text;
1280         }
1281
1282         /**
1283          * Create a new null-revision for insertion into a page's
1284          * history. This will not re-save the text, but simply refer
1285          * to the text from the previous version.
1286          *
1287          * Such revisions can for instance identify page rename
1288          * operations and other such meta-modifications.
1289          *
1290          * @param $dbw DatabaseBase
1291          * @param $pageId Integer: ID number of the page to read from
1292          * @param $summary String: revision's summary
1293          * @param $minor Boolean: whether the revision should be considered as minor
1294          * @return Revision|null on error
1295          */
1296         public static function newNullRevision( $dbw, $pageId, $summary, $minor ) {
1297                 global $wgContentHandlerUseDB;
1298
1299                 wfProfileIn( __METHOD__ );
1300
1301                 $fields = array( 'page_latest', 'page_namespace', 'page_title',
1302                                                 'rev_text_id', 'rev_len', 'rev_sha1' );
1303
1304                 if ( $wgContentHandlerUseDB ) {
1305                         $fields[] = 'rev_content_model';
1306                         $fields[] = 'rev_content_format';
1307                 }
1308
1309                 $current = $dbw->selectRow(
1310                         array( 'page', 'revision' ),
1311                         $fields,
1312                         array(
1313                                 'page_id' => $pageId,
1314                                 'page_latest=rev_id',
1315                                 ),
1316                         __METHOD__ );
1317
1318                 if( $current ) {
1319                         $row = array(
1320                                 'page'       => $pageId,
1321                                 'comment'    => $summary,
1322                                 'minor_edit' => $minor,
1323                                 'text_id'    => $current->rev_text_id,
1324                                 'parent_id'  => $current->page_latest,
1325                                 'len'        => $current->rev_len,
1326                                 'sha1'       => $current->rev_sha1
1327                         );
1328
1329                         if ( $wgContentHandlerUseDB ) {
1330                                 $row[ 'content_model' ] = $current->rev_content_model;
1331                                 $row[ 'content_format' ] = $current->rev_content_format;
1332                         }
1333
1334                         $revision = new Revision( $row );
1335                         $revision->setTitle( Title::makeTitle( $current->page_namespace, $current->page_title ) );
1336                 } else {
1337                         $revision = null;
1338                 }
1339
1340                 wfProfileOut( __METHOD__ );
1341                 return $revision;
1342         }
1343
1344         /**
1345          * Determine if the current user is allowed to view a particular
1346          * field of this revision, if it's marked as deleted.
1347          *
1348          * @param $field Integer:one of self::DELETED_TEXT,
1349          *                              self::DELETED_COMMENT,
1350          *                              self::DELETED_USER
1351          * @param $user User object to check, or null to use $wgUser
1352          * @return Boolean
1353          */
1354         public function userCan( $field, User $user = null ) {
1355                 return self::userCanBitfield( $this->mDeleted, $field, $user );
1356         }
1357
1358         /**
1359          * Determine if the current user is allowed to view a particular
1360          * field of this revision, if it's marked as deleted. This is used
1361          * by various classes to avoid duplication.
1362          *
1363          * @param $bitfield Integer: current field
1364          * @param $field Integer: one of self::DELETED_TEXT = File::DELETED_FILE,
1365          *                               self::DELETED_COMMENT = File::DELETED_COMMENT,
1366          *                               self::DELETED_USER = File::DELETED_USER
1367          * @param $user User object to check, or null to use $wgUser
1368          * @return Boolean
1369          */
1370         public static function userCanBitfield( $bitfield, $field, User $user = null ) {
1371                 if( $bitfield & $field ) { // aspect is deleted
1372                         if ( $bitfield & self::DELETED_RESTRICTED ) {
1373                                 $permission = 'suppressrevision';
1374                         } elseif ( $field & self::DELETED_TEXT ) {
1375                                 $permission = 'deletedtext';
1376                         } else {
1377                                 $permission = 'deletedhistory';
1378                         }
1379                         wfDebug( "Checking for $permission due to $field match on $bitfield\n" );
1380                         if ( $user === null ) {
1381                                 global $wgUser;
1382                                 $user = $wgUser;
1383                         }
1384                         return $user->isAllowed( $permission );
1385                 } else {
1386                         return true;
1387                 }
1388         }
1389
1390         /**
1391          * Get rev_timestamp from rev_id, without loading the rest of the row
1392          *
1393          * @param $title Title
1394          * @param $id Integer
1395          * @return String
1396          */
1397         static function getTimestampFromId( $title, $id ) {
1398                 $dbr = wfGetDB( DB_SLAVE );
1399                 // Casting fix for DB2
1400                 if ( $id == '' ) {
1401                         $id = 0;
1402                 }
1403                 $conds = array( 'rev_id' => $id );
1404                 $conds['rev_page'] = $title->getArticleID();
1405                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1406                 if ( $timestamp === false && wfGetLB()->getServerCount() > 1 ) {
1407                         # Not in slave, try master
1408                         $dbw = wfGetDB( DB_MASTER );
1409                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1410                 }
1411                 return wfTimestamp( TS_MW, $timestamp );
1412         }
1413
1414         /**
1415          * Get count of revisions per page...not very efficient
1416          *
1417          * @param $db DatabaseBase
1418          * @param $id Integer: page id
1419          * @return Integer
1420          */
1421         static function countByPageId( $db, $id ) {
1422                 $row = $db->selectRow( 'revision', 'COUNT(*) AS revCount',
1423                         array( 'rev_page' => $id ), __METHOD__ );
1424                 if( $row ) {
1425                         return $row->revCount;
1426                 }
1427                 return 0;
1428         }
1429
1430         /**
1431          * Get count of revisions per page...not very efficient
1432          *
1433          * @param $db DatabaseBase
1434          * @param $title Title
1435          * @return Integer
1436          */
1437         static function countByTitle( $db, $title ) {
1438                 $id = $title->getArticleID();
1439                 if( $id ) {
1440                         return Revision::countByPageId( $db, $id );
1441                 }
1442                 return 0;
1443         }
1444 }