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                         'page_is_redirect',
 409                         'page_len',
 410                 );
 411         }
 412
 413         /**
 414          * Return the list of user fields that should be selected from user table
 415          * @return array
 416          */
 417         public static function selectUserFields() {
 418                 return array( 'user_name' );
 419         }
 420
 421         /**
 422          * Constructor
 423          *
 424          * @param $row Mixed: either a database row or an array
 425          * @access private
 426          */
 427         function __construct( $row ) {
 428                 if( is_object( $row ) ) {
 429                         $this->mId        = intval( $row->rev_id );
 430                         $this->mPage      = intval( $row->rev_page );
 431                         $this->mTextId    = intval( $row->rev_text_id );
 432                         $this->mComment   =         $row->rev_comment;
 433                         $this->mUser      = intval( $row->rev_user );
 434                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 435                         $this->mTimestamp =         $row->rev_timestamp;
 436                         $this->mDeleted   = intval( $row->rev_deleted );
 437
 438                         if( !isset( $row->rev_parent_id ) ) {
 439                                 $this->mParentId = is_null( $row->rev_parent_id ) ? null : 0;
 440                         } else {
 441                                 $this->mParentId  = intval( $row->rev_parent_id );
 442                         }
 443
 444                         if( !isset( $row->rev_len ) || is_null( $row->rev_len ) ) {
 445                                 $this->mSize = null;
 446                         } else {
 447                                 $this->mSize = intval( $row->rev_len );
 448                         }
 449
 450                         if ( !isset( $row->rev_sha1 ) ) {
 451                                 $this->mSha1 = null;
 452                         } else {
 453                                 $this->mSha1 = $row->rev_sha1;
 454                         }
 455
 456                         if( isset( $row->page_latest ) ) {
 457                                 $this->mCurrent = ( $row->rev_id == $row->page_latest );
 458                                 $this->mTitle = Title::newFromRow( $row );
 459                         } else {
 460                                 $this->mCurrent = false;
 461                                 $this->mTitle = null;
 462                         }
 463
 464                         if( !isset( $row->rev_content_model ) || is_null( $row->rev_content_model ) ) {
 465                                 $this->mContentModel = null; # determine on demand if needed
 466                         } else {
 467                                 $this->mContentModel = intval( $row->rev_content_model );
 468                         }
 469
 470                         if( !isset( $row->rev_content_format ) || is_null( $row->rev_content_format ) ) {
 471                                 $this->mContentFormat = null; # determine on demand if needed
 472                         } else {
 473                                 $this->mContentFormat = intval( $row->rev_content_format );
 474                         }
 475
 476                         // Lazy extraction...
 477                         $this->mText      = null;
 478                         if( isset( $row->old_text ) ) {
 479                                 $this->mTextRow = $row;
 480                         } else {
 481                                 // 'text' table row entry will be lazy-loaded
 482                                 $this->mTextRow = null;
 483                         }
 484
 485                         // Use user_name for users and rev_user_text for IPs...
 486                         $this->mUserText = null; // lazy load if left null
 487                         if ( $this->mUser == 0 ) {
 488                                 $this->mUserText = $row->rev_user_text; // IP user
 489                         } elseif ( isset( $row->user_name ) ) {
 490                                 $this->mUserText = $row->user_name; // logged-in user
 491                         }
 492                         $this->mOrigUserText = $row->rev_user_text;
 493                 } elseif( is_array( $row ) ) {
 494                         // Build a new revision to be saved...
 495                         global $wgUser; // ugh
 496
 497
 498                         # if we have a content object, use it to set the model and type
 499                         if ( !empty( $row['content'] ) ) {
 500                                 if ( !empty( $row['text_id'] ) ) { //@todo: when is that set? test with external store setup! check out insertOn() [dk]
 501                                         throw new MWException( "Text already stored in external store (id {$row['text_id']}), can't serialize content object" );
 502                                 }
 503
 504                                 $row['content_model'] = $row['content']->getModel();
 505                                 # note: mContentFormat is initializes later accordingly
 506                                 # note: content is serialized later in this method!
 507                                 # also set text to null?
 508                         }
 509
 510                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 511                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 512                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 513                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 514                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 515                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 516                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestampNow();
 517                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 518                         $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
 519                         $this->mParentId  = isset( $row['parent_id']  ) ? intval( $row['parent_id']  ) : null;
 520                         $this->mSha1      = isset( $row['sha1']  )      ? strval( $row['sha1']  )      : null;
 521
 522                         $this->mContentModel = isset( $row['content_model']  )  ? intval( $row['content_model'] )  : null;
 523                         $this->mContentFormat    = isset( $row['content_format']  ) ? intval( $row['content_format'] ) : null;
 524
 525                         // Enforce spacing trimming on supplied text
 526                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 527                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 528                         $this->mTextRow   = null;
 529
 530                         # if we have a content object, override mText and mContentModel
 531                         if ( !empty( $row['content'] ) ) {
 532                                 $handler = $this->getContentHandler();
 533                                 $this->mContent = $row['content'];
 534
 535                                 $this->mContentModel = $this->mContent->getModel();
 536                                 $this->mContentHandler = null;
 537
 538                                 $this->mText = $handler->serializeContent( $row['content'], $this->getContentFormat() );
 539                         } elseif ( !is_null( $this->mText ) ) {
 540                                 $handler = $this->getContentHandler();
 541                                 $this->mContent = $handler->unserializeContent( $this->mText );
 542                         }
 543
 544                         $this->mTitle     = null; # Load on demand if needed
 545                         $this->mCurrent   = false; # XXX: really? we are about to create a revision. it will usually then be the current one.
 546
 547                         # If we still have no length, see it we have the text to figure it out
 548                         if ( !$this->mSize ) {
 549                                 if ( !is_null( $this->mContent ) ) {
 550                                         $this->mSize = $this->mContent->getSize();
 551                                 } else {
 552                                         #NOTE: this should never happen if we have either text or content object!
 553                                         $this->mSize = null;
 554                                 }
 555                         }
 556
 557                         # Same for sha1
 558                         if ( $this->mSha1 === null ) {
 559                                 $this->mSha1 = is_null( $this->mText ) ? null : self::base36Sha1( $this->mText );
 560                         }
 561
 562                         $this->getContentModel(); # force lazy init
 563                         $this->getContentFormat();    # force lazy init
 564                 } else {
 565                         throw new MWException( 'Revision constructor passed invalid row format.' );
 566                 }
 567                 $this->mUnpatrolled = null;
 568         }
 569
 570         /**
 571          * Get revision ID
 572          *
 573          * @return Integer|null
 574          */
 575         public function getId() {
 576                 return $this->mId;
 577         }
 578
 579         /**
 580          * Set the revision ID
 581          *
 582          * @since 1.19
 583          * @param $id Integer
 584          */
 585         public function setId( $id ) {
 586                 $this->mId = $id;
 587         }
 588
 589         /**
 590          * Get text row ID
 591          *
 592          * @return Integer|null
 593          */
 594         public function getTextId() {
 595                 return $this->mTextId;
 596         }
 597
 598         /**
 599          * Get parent revision ID (the original previous page revision)
 600          *
 601          * @return Integer|null
 602          */
 603         public function getParentId() {
 604                 return $this->mParentId;
 605         }
 606
 607         /**
 608          * Returns the length of the text in this revision, or null if unknown.
 609          *
 610          * @return Integer|null
 611          */
 612         public function getSize() {
 613                 return $this->mSize;
 614         }
 615
 616         /**
 617          * Returns the base36 sha1 of the text in this revision, or null if unknown.
 618          *
 619          * @return String|null
 620          */
 621         public function getSha1() {
 622                 return $this->mSha1;
 623         }
 624
 625         /**
 626          * Returns the title of the page associated with this entry or null.
 627          *
 628          * Will do a query, when title is not set and id is given.
 629          *
 630          * @return Title|null
 631          */
 632         public function getTitle() {
 633                 if( isset( $this->mTitle ) ) {
 634                         return $this->mTitle;
 635                 }
 636                 if( !is_null( $this->mId ) ) { //rev_id is defined as NOT NULL, but this revision may not yet have been inserted.
 637                         $dbr = wfGetDB( DB_SLAVE );
 638                         $row = $dbr->selectRow(
 639                                 array( 'page', 'revision' ),
 640                                 self::selectPageFields(),
 641                                 array( 'page_id=rev_page',
 642                                            'rev_id' => $this->mId ),
 643                                 __METHOD__ );
 644                         if ( $row ) {
 645                                 $this->mTitle = Title::newFromRow( $row );
 646                         }
 647                 }
 648
 649                 //@todo: as a last resort, perhaps load from page table, if $this->mPage is given?!
 650                 return $this->mTitle;
 651         }
 652
 653         /**
 654          * Set the title of the revision
 655          *
 656          * @param $title Title
 657          */
 658         public function setTitle( $title ) {
 659                 $this->mTitle = $title;
 660         }
 661
 662         /**
 663          * Get the page ID
 664          *
 665          * @return Integer|null
 666          */
 667         public function getPage() {
 668                 return $this->mPage;
 669         }
 670
 671         /**
 672          * Fetch revision's user id if it's available to the specified audience.
 673          * If the specified audience does not have access to it, zero will be
 674          * returned.
 675          *
 676          * @param $audience Integer: one of:
 677          *      Revision::FOR_PUBLIC       to be displayed to all users
 678          *      Revision::FOR_THIS_USER    to be displayed to the given user
 679          *      Revision::RAW              get the ID regardless of permissions
 680          * @param $user User object to check for, only if FOR_THIS_USER is passed
 681          *              to the $audience parameter
 682          * @return Integer
 683          */
 684         public function getUser( $audience = self::FOR_PUBLIC, User $user = null ) {
 685                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 686                         return 0;
 687                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
 688                         return 0;
 689                 } else {
 690                         return $this->mUser;
 691                 }
 692         }
 693
 694         /**
 695          * Fetch revision's user id without regard for the current user's permissions
 696          *
 697          * @return String
 698          */
 699         public function getRawUser() {
 700                 return $this->mUser;
 701         }
 702
 703         /**
 704          * Fetch revision's username if it's available to the specified audience.
 705          * If the specified audience does not have access to the username, an
 706          * empty string will be returned.
 707          *
 708          * @param $audience Integer: one of:
 709          *      Revision::FOR_PUBLIC       to be displayed to all users
 710          *      Revision::FOR_THIS_USER    to be displayed to the given user
 711          *      Revision::RAW              get the text regardless of permissions
 712          * @param $user User object to check for, only if FOR_THIS_USER is passed
 713          *              to the $audience parameter
 714          * @return string
 715          */
 716         public function getUserText( $audience = self::FOR_PUBLIC, User $user = null ) {
 717                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 718                         return '';
 719                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
 720                         return '';
 721                 } else {
 722                         return $this->getRawUserText();
 723                 }
 724         }
 725
 726         /**
 727          * Fetch revision's username without regard for view restrictions
 728          *
 729          * @return String
 730          */
 731         public function getRawUserText() {
 732                 if ( $this->mUserText === null ) {
 733                         $this->mUserText = User::whoIs( $this->mUser ); // load on demand
 734                         if ( $this->mUserText === false ) {
 735                                 # This shouldn't happen, but it can if the wiki was recovered
 736                                 # via importing revs and there is no user table entry yet.
 737                                 $this->mUserText = $this->mOrigUserText;
 738                         }
 739                 }
 740                 return $this->mUserText;
 741         }
 742
 743         /**
 744          * Fetch revision comment if it's available to the specified audience.
 745          * If the specified audience does not have access to the comment, an
 746          * empty string will be returned.
 747          *
 748          * @param $audience Integer: one of:
 749          *      Revision::FOR_PUBLIC       to be displayed to all users
 750          *      Revision::FOR_THIS_USER    to be displayed to the given user
 751          *      Revision::RAW              get the text regardless of permissions
 752          * @param $user User object to check for, only if FOR_THIS_USER is passed
 753          *              to the $audience parameter
 754          * @return String
 755          */
 756         function getComment( $audience = self::FOR_PUBLIC, User $user = null ) {
 757                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_COMMENT ) ) {
 758                         return '';
 759                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_COMMENT, $user ) ) {
 760                         return '';
 761                 } else {
 762                         return $this->mComment;
 763                 }
 764         }
 765
 766         /**
 767          * Fetch revision comment without regard for the current user's permissions
 768          *
 769          * @return String
 770          */
 771         public function getRawComment() {
 772                 return $this->mComment;
 773         }
 774
 775         /**
 776          * @return Boolean
 777          */
 778         public function isMinor() {
 779                 return (bool)$this->mMinorEdit;
 780         }
 781
 782         /**
 783          * @return Integer rcid of the unpatrolled row, zero if there isn't one
 784          */
 785         public function isUnpatrolled() {
 786                 if( $this->mUnpatrolled !== null ) {
 787                         return $this->mUnpatrolled;
 788                 }
 789                 $dbr = wfGetDB( DB_SLAVE );
 790                 $this->mUnpatrolled = $dbr->selectField( 'recentchanges',
 791                         'rc_id',
 792                         array( // Add redundant user,timestamp condition so we can use the existing index
 793                                 'rc_user_text'  => $this->getRawUserText(),
 794                                 'rc_timestamp'  => $dbr->timestamp( $this->getTimestamp() ),
 795                                 'rc_this_oldid' => $this->getId(),
 796                                 'rc_patrolled'  => 0
 797                         ),
 798                         __METHOD__
 799                 );
 800                 return (int)$this->mUnpatrolled;
 801         }
 802
 803         /**
 804          * @param $field int one of DELETED_* bitfield constants
 805          *
 806          * @return Boolean
 807          */
 808         public function isDeleted( $field ) {
 809                 return ( $this->mDeleted & $field ) == $field;
 810         }
 811
 812         /**
 813          * Get the deletion bitfield of the revision
 814          *
 815          * @return int
 816          */
 817         public function getVisibility() {
 818                 return (int)$this->mDeleted;
 819         }
 820
 821         /**
 822          * Fetch revision text if it's available to the specified audience.
 823          * If the specified audience does not have the ability to view this
 824          * revision, an empty string will be returned.
 825          *
 826          * @param $audience Integer: one of:
 827          *      Revision::FOR_PUBLIC       to be displayed to all users
 828          *      Revision::FOR_THIS_USER    to be displayed to the given user
 829          *      Revision::RAW              get the text regardless of permissions
 830          * @param $user User object to check for, only if FOR_THIS_USER is passed
 831          *              to the $audience parameter
 832          * @return String
 833          * @deprecated in 1.WD, use getContent() instead
 834          * @todo: replace usage in core
 835          */
 836         public function getText( $audience = self::FOR_PUBLIC, User $user = null ) {
 837                 wfDeprecated( __METHOD__, '1.WD' );
 838
 839                 $content = $this->getContent( $audience, $user );
 840                 return ContentHandler::getContentText( $content ); # returns the raw content text, if applicable
 841         }
 842
 843         /**
 844          * Fetch revision content if it's available to the specified audience.
 845          * If the specified audience does not have the ability to view this
 846          * revision, null will be returned.
 847          *
 848          * @param $audience Integer: one of:
 849          *      Revision::FOR_PUBLIC       to be displayed to all users
 850          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 851          *      Revision::RAW              get the text regardless of permissions
 852          * @param $user User object to check for, only if FOR_THIS_USER is passed
 853          *              to the $audience parameter
 854          * @return Content
 855          *
 856          * @since 1.WD
 857          */
 858         public function getContent( $audience = self::FOR_PUBLIC, User $user = null ) {
 859                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_TEXT ) ) {
 860                         return null;
 861                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_TEXT, $user ) ) {
 862                         return null;
 863                 } else {
 864                         return $this->getContentInternal();
 865                 }
 866         }
 867
 868         /**
 869          * Alias for getText(Revision::FOR_THIS_USER)
 870          *
 871          * @deprecated since 1.17
 872          * @return String
 873          */
 874         public function revText() {
 875                 wfDeprecated( __METHOD__, '1.17' );
 876                 return $this->getText( self::FOR_THIS_USER );
 877         }
 878
 879         /**
 880          * Fetch revision text without regard for view restrictions
 881          *
 882          * @return String
 883          *
 884          * @deprecated since 1.WD. Instead, use Revision::getContent( Revision::RAW ) or Revision::getSerializedData() as appropriate.
 885          */
 886         public function getRawText() {
 887                 wfDeprecated( __METHOD__, "1.WD" );
 888
 889                 return $this->getText( self::RAW );
 890         }
 891
 892         /**
 893          * Fetch original serialized data without regard for view restrictions
 894          *
 895          * @return String
 896          *
 897          * @since 1.WD
 898          */
 899         public function getSerializedData() {
 900                 return $this->mText;
 901         }
 902
 903         protected function getContentInternal() {
 904                 if( is_null( $this->mContent ) ) {
 905                         // Revision is immutable. Load on demand:
 906
 907                         $handler = $this->getContentHandler();
 908                         $format = $this->getContentFormat();
 909                         $title = $this->getTitle();
 910
 911                         if( is_null( $this->mText ) ) {
 912                                 // Load text on demand:
 913                                 $this->mText = $this->loadText();
 914                         }
 915
 916                         $this->mContent = is_null( $this->mText ) ? null : $handler->unserializeContent( $this->mText, $format );
 917                 }
 918
 919                 return $this->mContent;
 920         }
 921
 922         /**
 923          * Returns the content model for this revision.
 924          *
 925          * If no content model was stored in the database, $this->getTitle()->getContentModel() is
 926          * used to determine the content model to use. If no title is know, CONTENT_MODEL_WIKITEXT
 927          * is used as a last resort.
 928          *
 929          * @return int the content model id associated with this revision, see the CONTENT_MODEL_XXX constants.
 930          **/
 931         public function getContentModel() {
 932                 if ( !$this->mContentModel ) {
 933                         $title = $this->getTitle();
 934                         $this->mContentModel = ( $title ? $title->getContentModel() : CONTENT_MODEL_WIKITEXT );
 935
 936                         assert( !empty( $this->mContentModel ) );
 937                 }
 938
 939                 return $this->mContentModel;
 940         }
 941
 942         /**
 943          * Returns the content format for this revision.
 944          *
 945          * If no content format was stored in the database, the default format for this
 946          * revision's content model is returned.
 947          *
 948          * @return int the content format id associated with this revision, see the CONTENT_FORMAT_XXX constants.
 949          **/
 950         public function getContentFormat() {
 951                 if ( !$this->mContentFormat ) {
 952                         $handler = $this->getContentHandler();
 953                         $this->mContentFormat = $handler->getDefaultFormat();
 954
 955                         assert( !empty( $this->mContentFormat ) );
 956                 }
 957
 958                 return $this->mContentFormat;
 959         }
 960
 961         /**
 962          * Returns the content handler appropriate for this revision's content model.
 963          *
 964          * @return ContentHandler
 965          */
 966         public function getContentHandler() {
 967                 if ( !$this->mContentHandler ) {
 968                         $model = $this->getContentModel();
 969                         $this->mContentHandler = ContentHandler::getForModelID( $model );
 970
 971                         $format = $this->getContentFormat();
 972
 973                         if ( !$this->mContentHandler->isSupportedFormat( $format ) ) {
 974                                 $formatName = ContentHandler::getContentFormatMimeType( $format );
 975                                 $modelName = ContentHandler::getContentModelName( $model );
 976
 977                                 throw new MWException( "Oops, the content format #$format ($formatName) is not supported for this content model, #$model ($modelName)" );
 978                         }
 979                 }
 980
 981                 return $this->mContentHandler;
 982         }
 983
 984         /**
 985          * @return String
 986          */
 987         public function getTimestamp() {
 988                 return wfTimestamp( TS_MW, $this->mTimestamp );
 989         }
 990
 991         /**
 992          * @return Boolean
 993          */
 994         public function isCurrent() {
 995                 return $this->mCurrent;
 996         }
 997
 998         /**
 999          * Get previous revision for this title
1000          *
1001          * @return Revision or null
1002          */
1003         public function getPrevious() {
1004                 if( $this->getTitle() ) {
1005                         $prev = $this->getTitle()->getPreviousRevisionID( $this->getId() );
1006                         if( $prev ) {
1007                                 return Revision::newFromTitle( $this->getTitle(), $prev );
1008                         }
1009                 }
1010                 return null;
1011         }
1012
1013         /**
1014          * Get next revision for this title
1015          *
1016          * @return Revision or null
1017          */
1018         public function getNext() {
1019                 if( $this->getTitle() ) {
1020                         $next = $this->getTitle()->getNextRevisionID( $this->getId() );
1021                         if ( $next ) {
1022                                 return Revision::newFromTitle( $this->getTitle(), $next );
1023                         }
1024                 }
1025                 return null;
1026         }
1027
1028         /**
1029          * Get previous revision Id for this page_id
1030          * This is used to populate rev_parent_id on save
1031          *
1032          * @param $db DatabaseBase
1033          * @return Integer
1034          */
1035         private function getPreviousRevisionId( $db ) {
1036                 if( is_null( $this->mPage ) ) {
1037                         return 0;
1038                 }
1039                 # Use page_latest if ID is not given
1040                 if( !$this->mId ) {
1041                         $prevId = $db->selectField( 'page', 'page_latest',
1042                                 array( 'page_id' => $this->mPage ),
1043                                 __METHOD__ );
1044                 } else {
1045                         $prevId = $db->selectField( 'revision', 'rev_id',
1046                                 array( 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ),
1047                                 __METHOD__,
1048                                 array( 'ORDER BY' => 'rev_id DESC' ) );
1049                 }
1050                 return intval( $prevId );
1051         }
1052
1053         /**
1054           * Get revision text associated with an old or archive row
1055           * $row is usually an object from wfFetchRow(), both the flags and the text
1056           * field must be included
1057           *
1058           * @param $row Object: the text data
1059           * @param $prefix String: table prefix (default 'old_')
1060           * @return String: text the text requested or false on failure
1061           */
1062         public static function getRevisionText( $row, $prefix = 'old_' ) {
1063                 wfProfileIn( __METHOD__ );
1064
1065                 # Get data
1066                 $textField = $prefix . 'text';
1067                 $flagsField = $prefix . 'flags';
1068
1069                 if( isset( $row->$flagsField ) ) {
1070                         $flags = explode( ',', $row->$flagsField );
1071                 } else {
1072                         $flags = array();
1073                 }
1074
1075                 if( isset( $row->$textField ) ) {
1076                         $text = $row->$textField;
1077                 } else {
1078                         wfProfileOut( __METHOD__ );
1079                         return false;
1080                 }
1081
1082                 # Use external methods for external objects, text in table is URL-only then
1083                 if ( in_array( 'external', $flags ) ) {
1084                         $url = $text;
1085                         $parts = explode( '://', $url, 2 );
1086                         if( count( $parts ) == 1 || $parts[1] == '' ) {
1087                                 wfProfileOut( __METHOD__ );
1088                                 return false;
1089                         }
1090                         $text = ExternalStore::fetchFromURL( $url );
1091                 }
1092
1093                 // If the text was fetched without an error, convert it
1094                 if ( $text !== false ) {
1095                         if( in_array( 'gzip', $flags ) ) {
1096                                 # Deal with optional compression of archived pages.
1097                                 # This can be done periodically via maintenance/compressOld.php, and
1098                                 # as pages are saved if $wgCompressRevisions is set.
1099                                 $text = gzinflate( $text );
1100                         }
1101
1102                         if( in_array( 'object', $flags ) ) {
1103                                 # Generic compressed storage
1104                                 $obj = unserialize( $text );
1105                                 if ( !is_object( $obj ) ) {
1106                                         // Invalid object
1107                                         wfProfileOut( __METHOD__ );
1108                                         return false;
1109                                 }
1110                                 $text = $obj->getText();
1111                         }
1112
1113                         global $wgLegacyEncoding;
1114                         if( $text !== false && $wgLegacyEncoding
1115                                 && !in_array( 'utf-8', $flags ) && !in_array( 'utf8', $flags ) )
1116                         {
1117                                 # Old revisions kept around in a legacy encoding?
1118                                 # Upconvert on demand.
1119                                 # ("utf8" checked for compatibility with some broken
1120                                 #  conversion scripts 2008-12-30)
1121                                 global $wgContLang;
1122                                 $text = $wgContLang->iconv( $wgLegacyEncoding, 'UTF-8', $text );
1123                         }
1124                 }
1125                 wfProfileOut( __METHOD__ );
1126                 return $text;
1127         }
1128
1129         /**
1130          * If $wgCompressRevisions is enabled, we will compress data.
1131          * The input string is modified in place.
1132          * Return value is the flags field: contains 'gzip' if the
1133          * data is compressed, and 'utf-8' if we're saving in UTF-8
1134          * mode.
1135          *
1136          * @param $text Mixed: reference to a text
1137          * @return String
1138          */
1139         public static function compressRevisionText( &$text ) {
1140                 global $wgCompressRevisions;
1141                 $flags = array();
1142
1143                 # Revisions not marked this way will be converted
1144                 # on load if $wgLegacyCharset is set in the future.
1145                 $flags[] = 'utf-8';
1146
1147                 if( $wgCompressRevisions ) {
1148                         if( function_exists( 'gzdeflate' ) ) {
1149                                 $text = gzdeflate( $text );
1150                                 $flags[] = 'gzip';
1151                         } else {
1152                                 wfDebug( "Revision::compressRevisionText() -- no zlib support, not compressing\n" );
1153                         }
1154                 }
1155                 return implode( ',', $flags );
1156         }
1157
1158         /**
1159          * Insert a new revision into the database, returning the new revision ID
1160          * number on success and dies horribly on failure.
1161          *
1162          * @param $dbw DatabaseBase: (master connection)
1163          * @return Integer
1164          */
1165         public function insertOn( $dbw ) {
1166                 global $wgDefaultExternalStore, $wgContentHandlerUseDB;
1167
1168                 wfProfileIn( __METHOD__ );
1169
1170                 $data = $this->mText;
1171                 $flags = Revision::compressRevisionText( $data );
1172
1173                 # Write to external storage if required
1174                 if( $wgDefaultExternalStore ) {
1175                         // Store and get the URL
1176                         $data = ExternalStore::insertToDefault( $data );
1177                         if( !$data ) {
1178                                 throw new MWException( "Unable to store text to external storage" );
1179                         }
1180                         if( $flags ) {
1181                                 $flags .= ',';
1182                         }
1183                         $flags .= 'external';
1184                 }
1185
1186                 # Record the text (or external storage URL) to the text table
1187                 if( !isset( $this->mTextId ) ) {
1188                         $old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );
1189                         $dbw->insert( 'text',
1190                                 array(
1191                                         'old_id'    => $old_id,
1192                                         'old_text'  => $data,
1193                                         'old_flags' => $flags,
1194                                 ), __METHOD__
1195                         );
1196                         $this->mTextId = $dbw->insertId();
1197                 }
1198
1199                 if ( $this->mComment === null ) $this->mComment = "";
1200
1201                 # Record the edit in revisions
1202                 $rev_id = isset( $this->mId )
1203                         ? $this->mId
1204                         : $dbw->nextSequenceValue( 'revision_rev_id_seq' );
1205
1206                 $row = array(
1207                         'rev_id'         => $rev_id,
1208                         'rev_page'       => $this->mPage,
1209                         'rev_text_id'    => $this->mTextId,
1210                         'rev_comment'    => $this->mComment,
1211                         'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
1212                         'rev_user'       => $this->mUser,
1213                         'rev_user_text'  => $this->mUserText,
1214                         'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
1215                         'rev_deleted'    => $this->mDeleted,
1216                         'rev_len'        => $this->mSize,
1217                         'rev_parent_id'  => is_null( $this->mParentId )
1218                                 ? $this->getPreviousRevisionId( $dbw )
1219                                 : $this->mParentId,
1220                         'rev_sha1'       => is_null( $this->mSha1 )
1221                                 ? Revision::base36Sha1( $this->mText )
1222                                 : $this->mSha1,
1223                 );
1224
1225                 if ( $wgContentHandlerUseDB ) {
1226                         $row[ 'rev_content_model' ] = $this->getContentModel();
1227                         $row[ 'rev_content_format' ] = $this->getContentFormat();
1228                 }
1229
1230                 $this->checkContentModel();
1231
1232                 $dbw->insert( 'revision', $row, __METHOD__ );
1233
1234                 $this->mId = !is_null( $rev_id ) ? $rev_id : $dbw->insertId();
1235
1236                 wfRunHooks( 'RevisionInsertComplete', array( &$this, $data, $flags ) );
1237
1238                 wfProfileOut( __METHOD__ );
1239                 return $this->mId;
1240         }
1241
1242         protected function checkContentModel() {
1243                 global $wgContentHandlerUseDB;
1244
1245                 $title = $this->getTitle(); //note: returns null for revisions that have not yet been inserted.
1246
1247                 $model = $this->getContentModel();
1248                 $format = $this->getContentFormat();
1249                 $handler = $this->getContentHandler();
1250
1251                 if ( !$handler->isSupportedFormat( $format ) ) {
1252                         $t = $title->getPrefixedDBkey();
1253                         $modelName = ContentHandler::getContentModelName( $model );
1254                         $formatName = ContentHandler::getContentFormatMimeType( $format );
1255
1256                         throw new MWException( "Can't use format #$format ($formatName) with content model #$model ($modelName) on $t" );
1257                 }
1258
1259                 if ( !$wgContentHandlerUseDB && $title ) {
1260                         // if $wgContentHandlerUseDB is not set, all revisions must use the default content model and format.
1261
1262                         $defaultModel = ContentHandler::getDefaultModelFor( $title );
1263                         $defaultHandler = ContentHandler::getForModelID( $defaultModel );
1264                         $defaultFormat = $defaultHandler->getDefaultFormat();
1265
1266                         if ( $this->getContentModel() != $defaultModel ) {
1267                                 $defaultModelName = ContentHandler::getContentModelName( $defaultModel );
1268                                 $modelName = ContentHandler::getContentModelName( $model );
1269                                 $t = $title->getPrefixedDBkey();
1270
1271                                 throw new MWException( "Can't save non-default content model with \$wgContentHandlerUseDB disabled: model is #$model ($modelName), default for $t is #$defaultModel ($defaultModelName)" );
1272                         }
1273
1274                         if ( $this->getContentFormat() != $defaultFormat ) {
1275                                 $defaultFormatName = ContentHandler::getContentFormatMimeType( $defaultFormat );
1276                                 $formatName = ContentHandler::getContentFormatMimeType( $format );
1277                                 $t = $title->getPrefixedDBkey();
1278
1279                                 throw new MWException( "Can't use non-default content format with \$wgContentHandlerUseDB disabled: format is #$format ($formatName), default for $t is #$defaultFormat ($defaultFormatName)" );
1280                         }
1281                 }
1282
1283                 $content = $this->getContent( Revision::RAW );
1284
1285                 if ( !$content->isValid() ) {
1286                         $t = $title->getPrefixedDBkey();
1287                         $modelName = ContentHandler::getContentModelName( $model );
1288
1289                         throw new MWException( "Content of $t is not valid! Content model is #$model ($modelName)" );
1290                 }
1291         }
1292
1293         /**
1294          * Get the base 36 SHA-1 value for a string of text
1295          * @param $text String
1296          * @return String
1297          */
1298         public static function base36Sha1( $text ) {
1299                 return wfBaseConvert( sha1( $text ), 16, 36, 31 );
1300         }
1301
1302         /**
1303          * Lazy-load the revision's text.
1304          * Currently hardcoded to the 'text' table storage engine.
1305          *
1306          * @return String
1307          */
1308         protected function loadText() {
1309                 wfProfileIn( __METHOD__ );
1310
1311                 // Caching may be beneficial for massive use of external storage
1312                 global $wgRevisionCacheExpiry, $wgMemc;
1313                 $textId = $this->getTextId();
1314                 $key = wfMemcKey( 'revisiontext', 'textid', $textId );
1315                 if( $wgRevisionCacheExpiry ) {
1316                         $text = $wgMemc->get( $key );
1317                         if( is_string( $text ) ) {
1318                                 wfDebug( __METHOD__ . ": got id $textId from cache\n" );
1319                                 wfProfileOut( __METHOD__ );
1320                                 return $text;
1321                         }
1322                 }
1323
1324                 // If we kept data for lazy extraction, use it now...
1325                 if ( isset( $this->mTextRow ) ) {
1326                         $row = $this->mTextRow;
1327                         $this->mTextRow = null;
1328                 } else {
1329                         $row = null;
1330                 }
1331
1332                 if( !$row ) {
1333                         // Text data is immutable; check slaves first.
1334                         $dbr = wfGetDB( DB_SLAVE );
1335                         $row = $dbr->selectRow( 'text',
1336                                 array( 'old_text', 'old_flags' ),
1337                                 array( 'old_id' => $this->getTextId() ),
1338                                 __METHOD__ );
1339                 }
1340
1341                 if( !$row && wfGetLB()->getServerCount() > 1 ) {
1342                         // Possible slave lag!
1343                         $dbw = wfGetDB( DB_MASTER );
1344                         $row = $dbw->selectRow( 'text',
1345                                 array( 'old_text', 'old_flags' ),
1346                                 array( 'old_id' => $this->getTextId() ),
1347                                 __METHOD__ );
1348                 }
1349
1350                 $text = self::getRevisionText( $row );
1351
1352                 # No negative caching -- negative hits on text rows may be due to corrupted slave servers
1353                 if( $wgRevisionCacheExpiry && $text !== false ) {
1354                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
1355                 }
1356
1357                 wfProfileOut( __METHOD__ );
1358
1359                 return $text;
1360         }
1361
1362         /**
1363          * Create a new null-revision for insertion into a page's
1364          * history. This will not re-save the text, but simply refer
1365          * to the text from the previous version.
1366          *
1367          * Such revisions can for instance identify page rename
1368          * operations and other such meta-modifications.
1369          *
1370          * @param $dbw DatabaseBase
1371          * @param $pageId Integer: ID number of the page to read from
1372          * @param $summary String: revision's summary
1373          * @param $minor Boolean: whether the revision should be considered as minor
1374          * @return Revision|null on error
1375          */
1376         public static function newNullRevision( $dbw, $pageId, $summary, $minor ) {
1377                 global $wgContentHandlerUseDB;
1378
1379                 wfProfileIn( __METHOD__ );
1380
1381                 $fields = array( 'page_latest', 'page_namespace', 'page_title',
1382                                                 'rev_text_id', 'rev_len', 'rev_sha1' );
1383
1384                 if ( $wgContentHandlerUseDB ) {
1385                         $fields[] = 'rev_content_model';
1386                         $fields[] = 'rev_content_format';
1387                 }
1388
1389                 $current = $dbw->selectRow(
1390                         array( 'page', 'revision' ),
1391                         $fields,
1392                         array(
1393                                 'page_id' => $pageId,
1394                                 'page_latest=rev_id',
1395                                 ),
1396                         __METHOD__ );
1397
1398                 if( $current ) {
1399                         $row = array(
1400                                 'page'       => $pageId,
1401                                 'comment'    => $summary,
1402                                 'minor_edit' => $minor,
1403                                 'text_id'    => $current->rev_text_id,
1404                                 'parent_id'  => $current->page_latest,
1405                                 'len'        => $current->rev_len,
1406                                 'sha1'       => $current->rev_sha1
1407                         );
1408
1409                         if ( $wgContentHandlerUseDB ) {
1410                                 $row[ 'content_model' ] = $current->rev_content_model;
1411                                 $row[ 'content_format' ] = $current->rev_content_format;
1412                         }
1413
1414                         $revision = new Revision( $row );
1415                         $revision->setTitle( Title::makeTitle( $current->page_namespace, $current->page_title ) );
1416                 } else {
1417                         $revision = null;
1418                 }
1419
1420                 wfProfileOut( __METHOD__ );
1421                 return $revision;
1422         }
1423
1424         /**
1425          * Determine if the current user is allowed to view a particular
1426          * field of this revision, if it's marked as deleted.
1427          *
1428          * @param $field Integer:one of self::DELETED_TEXT,
1429          *                              self::DELETED_COMMENT,
1430          *                              self::DELETED_USER
1431          * @param $user User object to check, or null to use $wgUser
1432          * @return Boolean
1433          */
1434         public function userCan( $field, User $user = null ) {
1435                 return self::userCanBitfield( $this->mDeleted, $field, $user );
1436         }
1437
1438         /**
1439          * Determine if the current user is allowed to view a particular
1440          * field of this revision, if it's marked as deleted. This is used
1441          * by various classes to avoid duplication.
1442          *
1443          * @param $bitfield Integer: current field
1444          * @param $field Integer: one of self::DELETED_TEXT = File::DELETED_FILE,
1445          *                               self::DELETED_COMMENT = File::DELETED_COMMENT,
1446          *                               self::DELETED_USER = File::DELETED_USER
1447          * @param $user User object to check, or null to use $wgUser
1448          * @return Boolean
1449          */
1450         public static function userCanBitfield( $bitfield, $field, User $user = null ) {
1451                 if( $bitfield & $field ) { // aspect is deleted
1452                         if ( $bitfield & self::DELETED_RESTRICTED ) {
1453                                 $permission = 'suppressrevision';
1454                         } elseif ( $field & self::DELETED_TEXT ) {
1455                                 $permission = 'deletedtext';
1456                         } else {
1457                                 $permission = 'deletedhistory';
1458                         }
1459                         wfDebug( "Checking for $permission due to $field match on $bitfield\n" );
1460                         if ( $user === null ) {
1461                                 global $wgUser;
1462                                 $user = $wgUser;
1463                         }
1464                         return $user->isAllowed( $permission );
1465                 } else {
1466                         return true;
1467                 }
1468         }
1469
1470         /**
1471          * Get rev_timestamp from rev_id, without loading the rest of the row
1472          *
1473          * @param $title Title
1474          * @param $id Integer
1475          * @return String
1476          */
1477         static function getTimestampFromId( $title, $id ) {
1478                 $dbr = wfGetDB( DB_SLAVE );
1479                 // Casting fix for DB2
1480                 if ( $id == '' ) {
1481                         $id = 0;
1482                 }
1483                 $conds = array( 'rev_id' => $id );
1484                 $conds['rev_page'] = $title->getArticleID();
1485                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1486                 if ( $timestamp === false && wfGetLB()->getServerCount() > 1 ) {
1487                         # Not in slave, try master
1488                         $dbw = wfGetDB( DB_MASTER );
1489                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1490                 }
1491                 return wfTimestamp( TS_MW, $timestamp );
1492         }
1493
1494         /**
1495          * Get count of revisions per page...not very efficient
1496          *
1497          * @param $db DatabaseBase
1498          * @param $id Integer: page id
1499          * @return Integer
1500          */
1501         static function countByPageId( $db, $id ) {
1502                 $row = $db->selectRow( 'revision', 'COUNT(*) AS revCount',
1503                         array( 'rev_page' => $id ), __METHOD__ );
1504                 if( $row ) {
1505                         return $row->revCount;
1506                 }
1507                 return 0;
1508         }
1509
1510         /**
1511          * Get count of revisions per page...not very efficient
1512          *
1513          * @param $db DatabaseBase
1514          * @param $title Title
1515          * @return Integer
1516          */
1517         static function countByTitle( $db, $title ) {
1518                 $id = $title->getArticleID();
1519                 if( $id ) {
1520                         return Revision::countByPageId( $db, $id );
1521                 }
1522                 return 0;
1523         }
1524 }