includes/Revision.php

   1 <?php
   2 /**
   3  * @todo document
   4  * @file
   5  */
   6
   7 /**
   8  * @todo document
   9  */
  10 class Revision {
  11         const DELETED_TEXT = 1;
  12         const DELETED_COMMENT = 2;
  13         const DELETED_USER = 4;
  14         const DELETED_RESTRICTED = 8;
  15         // Convenience field
  16         const SUPPRESSED_USER = 12;
  17         // Audience options for Revision::getText()
  18         const FOR_PUBLIC = 1;
  19         const FOR_THIS_USER = 2;
  20         const RAW = 3;
  21
  22         /**
  23          * Load a page revision from a given revision ID number.
  24          * Returns null if no such revision can be found.
  25          *
  26          * @param int $id
  27          * @access public
  28          * @static
  29          */
  30         public static function newFromId( $id ) {
  31                 return Revision::newFromConds(
  32                         array( 'page_id=rev_page',
  33                                'rev_id' => intval( $id ) ) );
  34         }
  35
  36         /**
  37          * Load either the current, or a specified, revision
  38          * that's attached to a given title. If not attached
  39          * to that title, will return null.
  40          *
  41          * @param Title $title
  42          * @param int $id
  43          * @return Revision
  44          */
  45         public static function newFromTitle( $title, $id = 0 ) {
  46                 $conds = array(
  47                         'page_namespace' => $title->getNamespace(),
  48                         'page_title' => $title->getDBkey()
  49                 );
  50                 if ( $id ) {
  51                         // Use the specified ID
  52                         $conds['rev_id'] = $id;
  53                 } elseif ( wfGetLB()->getServerCount() > 1 ) {
  54                         // Get the latest revision ID from the master
  55                         $dbw = wfGetDB( DB_MASTER );
  56                         $latest = $dbw->selectField( 'page', 'page_latest', $conds, __METHOD__ );
  57                         if ( $latest === false ) {
  58                                 // Page does not exist
  59                                 return null;
  60                         }
  61                         $conds['rev_id'] = $latest;
  62                 } else {
  63                         // Use a join to get the latest revision
  64                         $conds[] = 'rev_id=page_latest';
  65                 }
  66                 $conds[] = 'page_id=rev_page';
  67                 return Revision::newFromConds( $conds );
  68         }
  69
  70         /**
  71          * Make a fake revision object from an archive table row. This is queried
  72          * for permissions or even inserted (as in Special:Undelete)
  73          * @todo Fixme: should be a subclass for RevisionDelete. [TS]
  74          */
  75         public static function newFromArchiveRow( $row, $overrides = array() ) {
  76                 $attribs = $overrides + array(
  77                         'page'       => isset( $row->page_id ) ? $row->page_id : null,
  78                         'id'         => isset( $row->ar_rev_id ) ? $row->ar_rev_id : null,
  79                         'comment'    => $row->ar_comment,
  80                         'user'       => $row->ar_user,
  81                         'user_text'  => $row->ar_user_text,
  82                         'timestamp'  => $row->ar_timestamp,
  83                         'minor_edit' => $row->ar_minor_edit,
  84                         'text_id'    => isset( $row->ar_text_id ) ? $row->ar_text_id : null,
  85                         'deleted'    => $row->ar_deleted,
  86                         'len'        => $row->ar_len);
  87                 if ( isset( $row->ar_text ) && !$row->ar_text_id ) {
  88                         // Pre-1.5 ar_text row
  89                         $attribs['text'] = self::getRevisionText( $row, 'ar_' );
  90                 }
  91                 return new self( $attribs );
  92         }
  93
  94         /**
  95          * Load a page revision from a given revision ID number.
  96          * Returns null if no such revision can be found.
  97          *
  98          * @param Database $db
  99          * @param int $id
 100          * @access public
 101          * @static
 102          */
 103         public static function loadFromId( $db, $id ) {
 104                 return Revision::loadFromConds( $db,
 105                         array( 'page_id=rev_page',
 106                                'rev_id' => intval( $id ) ) );
 107         }
 108
 109         /**
 110          * Load either the current, or a specified, revision
 111          * that's attached to a given page. If not attached
 112          * to that page, will return null.
 113          *
 114          * @param Database $db
 115          * @param int $pageid
 116          * @param int $id
 117          * @return Revision
 118          * @access public
 119          * @static
 120          */
 121         public static function loadFromPageId( $db, $pageid, $id = 0 ) {
 122                 $conds = array( 'page_id=rev_page','rev_page' => intval( $pageid ), 'page_id'=>intval( $pageid ) );
 123                 if( $id ) {
 124                         $conds['rev_id'] = intval( $id );
 125                 } else {
 126                         $conds[] = 'rev_id=page_latest';
 127                 }
 128                 return Revision::loadFromConds( $db, $conds );
 129         }
 130
 131         /**
 132          * Load either the current, or a specified, revision
 133          * that's attached to a given page. If not attached
 134          * to that page, will return null.
 135          *
 136          * @param Database $db
 137          * @param Title $title
 138          * @param int $id
 139          * @return Revision
 140          * @access public
 141          * @static
 142          */
 143         public static function loadFromTitle( $db, $title, $id = 0 ) {
 144                 if( $id ) {
 145                         $matchId = intval( $id );
 146                 } else {
 147                         $matchId = 'page_latest';
 148                 }
 149                 return Revision::loadFromConds(
 150                         $db,
 151                         array( "rev_id=$matchId",
 152                                'page_id=rev_page',
 153                                'page_namespace' => $title->getNamespace(),
 154                                'page_title'     => $title->getDBkey() ) );
 155         }
 156
 157         /**
 158          * Load the revision for the given title with the given timestamp.
 159          * WARNING: Timestamps may in some circumstances not be unique,
 160          * so this isn't the best key to use.
 161          *
 162          * @param Database $db
 163          * @param Title $title
 164          * @param string $timestamp
 165          * @return Revision
 166          * @access public
 167          * @static
 168          */
 169         public static function loadFromTimestamp( $db, $title, $timestamp ) {
 170                 return Revision::loadFromConds(
 171                         $db,
 172                         array( 'rev_timestamp'  => $db->timestamp( $timestamp ),
 173                                'page_id=rev_page',
 174                                'page_namespace' => $title->getNamespace(),
 175                                'page_title'     => $title->getDBkey() ) );
 176         }
 177
 178         /**
 179          * Given a set of conditions, fetch a revision.
 180          *
 181          * @param array $conditions
 182          * @return Revision
 183          * @access private
 184          * @static
 185          */
 186         public static function newFromConds( $conditions ) {
 187                 $db = wfGetDB( DB_SLAVE );
 188                 $row = Revision::loadFromConds( $db, $conditions );
 189                 if( is_null( $row ) && wfGetLB()->getServerCount() > 1 ) {
 190                         $dbw = wfGetDB( DB_MASTER );
 191                         $row = Revision::loadFromConds( $dbw, $conditions );
 192                 }
 193                 return $row;
 194         }
 195
 196         /**
 197          * Given a set of conditions, fetch a revision from
 198          * the given database connection.
 199          *
 200          * @param Database $db
 201          * @param array $conditions
 202          * @return Revision
 203          * @access private
 204          * @static
 205          */
 206         private static function loadFromConds( $db, $conditions ) {
 207                 $res = Revision::fetchFromConds( $db, $conditions );
 208                 if( $res ) {
 209                         $row = $res->fetchObject();
 210                         $res->free();
 211                         if( $row ) {
 212                                 $ret = new Revision( $row );
 213                                 return $ret;
 214                         }
 215                 }
 216                 $ret = null;
 217                 return $ret;
 218         }
 219
 220         /**
 221          * Return a wrapper for a series of database rows to
 222          * fetch all of a given page's revisions in turn.
 223          * Each row can be fed to the constructor to get objects.
 224          *
 225          * @param Title $title
 226          * @return ResultWrapper
 227          * @access public
 228          * @static
 229          */
 230         public static function fetchRevision( $title ) {
 231                 return Revision::fetchFromConds(
 232                         wfGetDB( DB_SLAVE ),
 233                         array( 'rev_id=page_latest',
 234                                'page_namespace' => $title->getNamespace(),
 235                                'page_title'     => $title->getDBkey(),
 236                                'page_id=rev_page' ) );
 237         }
 238
 239         /**
 240          * Given a set of conditions, return a ResultWrapper
 241          * which will return matching database rows with the
 242          * fields necessary to build Revision objects.
 243          *
 244          * @param Database $db
 245          * @param array $conditions
 246          * @return ResultWrapper
 247          * @access private
 248          * @static
 249          */
 250         private static function fetchFromConds( $db, $conditions ) {
 251                 $fields = self::selectFields();
 252                 $fields[] = 'page_namespace';
 253                 $fields[] = 'page_title';
 254                 $fields[] = 'page_latest';
 255                 $res = $db->select(
 256                         array( 'page', 'revision' ),
 257                         $fields,
 258                         $conditions,
 259                         __METHOD__,
 260                         array( 'LIMIT' => 1 ) );
 261                 $ret = $db->resultObject( $res );
 262                 return $ret;
 263         }
 264
 265         /**
 266          * Return the list of revision fields that should be selected to create
 267          * a new revision.
 268          */
 269         static function selectFields() {
 270                 return array(
 271                         'rev_id',
 272                         'rev_page',
 273                         'rev_text_id',
 274                         'rev_timestamp',
 275                         'rev_comment',
 276                         'rev_user_text,'.
 277                         'rev_user',
 278                         'rev_minor_edit',
 279                         'rev_deleted',
 280                         'rev_len',
 281                         'rev_parent_id'
 282                 );
 283         }
 284
 285         /**
 286          * Return the list of text fields that should be selected to read the
 287          * revision text
 288          */
 289         static function selectTextFields() {
 290                 return array(
 291                         'old_text',
 292                         'old_flags'
 293                 );
 294         }
 295
 296         /**
 297          * Return the list of page fields that should be selected from page table
 298          */
 299         static function selectPageFields() {
 300                 return array(
 301                         'page_namespace',
 302                         'page_title',
 303                         'page_latest'
 304                 );
 305         }
 306
 307         /**
 308          * @param object $row
 309          * @access private
 310          */
 311         function Revision( $row ) {
 312                 if( is_object( $row ) ) {
 313                         $this->mId        = intval( $row->rev_id );
 314                         $this->mPage      = intval( $row->rev_page );
 315                         $this->mTextId    = intval( $row->rev_text_id );
 316                         $this->mComment   =         $row->rev_comment;
 317                         $this->mUserText  =         $row->rev_user_text;
 318                         $this->mUser      = intval( $row->rev_user );
 319                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 320                         $this->mTimestamp =         $row->rev_timestamp;
 321                         $this->mDeleted   = intval( $row->rev_deleted );
 322
 323                         if( !isset( $row->rev_parent_id ) )
 324                                 $this->mParentId = is_null($row->rev_parent_id) ? null : 0;
 325                         else
 326                                 $this->mParentId  = intval( $row->rev_parent_id );
 327
 328                         if( !isset( $row->rev_len ) || is_null( $row->rev_len ) )
 329                                 $this->mSize = null;
 330                         else
 331                                 $this->mSize = intval( $row->rev_len );
 332
 333                         if( isset( $row->page_latest ) ) {
 334                                 $this->mCurrent = ( $row->rev_id == $row->page_latest );
 335                                 $this->mTitle = Title::makeTitle( $row->page_namespace, $row->page_title );
 336                                 $this->mTitle->resetArticleID( $this->mPage );
 337                         } else {
 338                                 $this->mCurrent = false;
 339                                 $this->mTitle = null;
 340                         }
 341
 342                         // Lazy extraction...
 343                         $this->mText      = null;
 344                         if( isset( $row->old_text ) ) {
 345                                 $this->mTextRow = $row;
 346                         } else {
 347                                 // 'text' table row entry will be lazy-loaded
 348                                 $this->mTextRow = null;
 349                         }
 350                 } elseif( is_array( $row ) ) {
 351                         // Build a new revision to be saved...
 352                         global $wgUser;
 353
 354                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 355                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 356                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 357                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 358                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 359                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 360                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestamp( TS_MW );
 361                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 362                         $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
 363                         $this->mParentId  = isset( $row['parent_id']  ) ? intval( $row['parent_id']  ) : null;
 364
 365                         // Enforce spacing trimming on supplied text
 366                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 367                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 368                         $this->mTextRow   = null;
 369
 370                         $this->mTitle     = null; # Load on demand if needed
 371                         $this->mCurrent   = false;
 372                         # If we still have no len_size, see it we have the text to figure it out
 373                         if ( !$this->mSize )
 374                                 $this->mSize      = is_null( $this->mText ) ? null : strlen( $this->mText );
 375                 } else {
 376                         throw new MWException( 'Revision constructor passed invalid row format.' );
 377                 }
 378                 $this->mUnpatrolled = null;
 379         }
 380
 381         /**#@+
 382          * @access public
 383          */
 384
 385         /**
 386          * Get revision ID
 387          * @return int
 388          */
 389         public function getId() {
 390                 return $this->mId;
 391         }
 392
 393         /**
 394          * Get text row ID
 395          * @return int
 396          */
 397         public function getTextId() {
 398                 return $this->mTextId;
 399         }
 400
 401         /**
 402          * Get parent revision ID (the original previous page revision)
 403          * @return int
 404          */
 405         public function getParentId() {
 406                 return $this->mParentId;
 407         }
 408
 409         /**
 410          * Returns the length of the text in this revision, or null if unknown.
 411          * @return int
 412          */
 413         public function getSize() {
 414                 return $this->mSize;
 415         }
 416
 417         /**
 418          * Returns the title of the page associated with this entry.
 419          * @return Title
 420          */
 421         public function getTitle() {
 422                 if( isset( $this->mTitle ) ) {
 423                         return $this->mTitle;
 424                 }
 425                 $dbr = wfGetDB( DB_SLAVE );
 426                 $row = $dbr->selectRow(
 427                         array( 'page', 'revision' ),
 428                         array( 'page_namespace', 'page_title' ),
 429                         array( 'page_id=rev_page',
 430                                'rev_id' => $this->mId ),
 431                         'Revision::getTitle' );
 432                 if( $row ) {
 433                         $this->mTitle = Title::makeTitle( $row->page_namespace,
 434                                                           $row->page_title );
 435                 }
 436                 return $this->mTitle;
 437         }
 438
 439         /**
 440          * Set the title of the revision
 441          * @param Title $title
 442          */
 443         public function setTitle( $title ) {
 444                 $this->mTitle = $title;
 445         }
 446
 447         /**
 448          * Get the page ID
 449          * @return int
 450          */
 451         public function getPage() {
 452                 return $this->mPage;
 453         }
 454
 455         /**
 456          * Fetch revision's user id if it's available to the specified audience.
 457          * If the specified audience does not have access to it, zero will be
 458          * returned.
 459          *
 460          * @param integer $audience One of:
 461          *      Revision::FOR_PUBLIC       to be displayed to all users
 462          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 463          *      Revision::RAW              get the ID regardless of permissions
 464          *
 465          *
 466          * @return int
 467          */
 468         public function getUser( $audience = self::FOR_PUBLIC ) {
 469                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 470                         return 0;
 471                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER ) ) {
 472                         return 0;
 473                 } else {
 474                         return $this->mUser;
 475                 }
 476         }
 477
 478         /**
 479          * Fetch revision's user id without regard for the current user's permissions
 480          * @return string
 481          */
 482         public function getRawUser() {
 483                 return $this->mUser;
 484         }
 485
 486         /**
 487          * Fetch revision's username if it's available to the specified audience.
 488          * If the specified audience does not have access to the username, an
 489          * empty string will be returned.
 490          *
 491          * @param integer $audience One of:
 492          *      Revision::FOR_PUBLIC       to be displayed to all users
 493          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 494          *      Revision::RAW              get the text regardless of permissions
 495          *
 496          * @return string
 497          */
 498         public function getUserText( $audience = self::FOR_PUBLIC ) {
 499                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 500                         return '';
 501                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER ) ) {
 502                         return '';
 503                 } else {
 504                         return $this->mUserText;
 505                 }
 506         }
 507
 508         /**
 509          * Fetch revision's username without regard for view restrictions
 510          * @return string
 511          */
 512         public function getRawUserText() {
 513                 return $this->mUserText;
 514         }
 515
 516         /**
 517          * Fetch revision comment if it's available to the specified audience.
 518          * If the specified audience does not have access to the comment, an
 519          * empty string will be returned.
 520          *
 521          * @param integer $audience One of:
 522          *      Revision::FOR_PUBLIC       to be displayed to all users
 523          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 524          *      Revision::RAW              get the text regardless of permissions
 525          *
 526          * @return string
 527          */
 528         function getComment( $audience = self::FOR_PUBLIC ) {
 529                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_COMMENT ) ) {
 530                         return '';
 531                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_COMMENT ) ) {
 532                         return '';
 533                 } else {
 534                         return $this->mComment;
 535                 }
 536         }
 537
 538         /**
 539          * Fetch revision comment without regard for the current user's permissions
 540          * @return string
 541          */
 542         public function getRawComment() {
 543                 return $this->mComment;
 544         }
 545
 546         /**
 547          * @return bool
 548          */
 549         public function isMinor() {
 550                 return (bool)$this->mMinorEdit;
 551         }
 552
 553         /**
 554          * @return int rcid of the unpatrolled row, zero if there isn't one
 555          */
 556         public function isUnpatrolled() {
 557                 if( $this->mUnpatrolled !== null ) {
 558                         return $this->mUnpatrolled;
 559                 }
 560                 $dbr = wfGetDB( DB_SLAVE );
 561                 $this->mUnpatrolled = $dbr->selectField( 'recentchanges',
 562                         'rc_id',
 563                         array( // Add redundant user,timestamp condition so we can use the existing index
 564                                 'rc_user_text'  => $this->getRawUserText(),
 565                                 'rc_timestamp'  => $dbr->timestamp( $this->getTimestamp() ),
 566                                 'rc_this_oldid' => $this->getId(),
 567                                 'rc_patrolled'  => 0
 568                         ),
 569                         __METHOD__
 570                 );
 571                 return (int)$this->mUnpatrolled;
 572         }
 573
 574         /**
 575          * int $field one of DELETED_* bitfield constants
 576          * @return bool
 577          */
 578         public function isDeleted( $field ) {
 579                 return ( $this->mDeleted & $field ) == $field;
 580         }
 581
 582         /**
 583          * Get the deletion bitfield of the revision
 584          */
 585         public function getVisibility() {
 586                 return (int)$this->mDeleted;
 587         }
 588
 589         /**
 590          * Fetch revision text if it's available to the specified audience.
 591          * If the specified audience does not have the ability to view this
 592          * revision, an empty string will be returned.
 593          *
 594          * @param integer $audience One of:
 595          *      Revision::FOR_PUBLIC       to be displayed to all users
 596          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 597          *      Revision::RAW              get the text regardless of permissions
 598          *
 599          *
 600          * @return string
 601          */
 602         public function getText( $audience = self::FOR_PUBLIC ) {
 603                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_TEXT ) ) {
 604                         return '';
 605                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_TEXT ) ) {
 606                         return '';
 607                 } else {
 608                         return $this->getRawText();
 609                 }
 610         }
 611
 612         /**
 613          * Alias for getText(Revision::FOR_THIS_USER)
 614          */
 615         public function revText() {
 616                 return $this->getText( self::FOR_THIS_USER );
 617         }
 618
 619         /**
 620          * Fetch revision text without regard for view restrictions
 621          * @return string
 622          */
 623         public function getRawText() {
 624                 if( is_null( $this->mText ) ) {
 625                         // Revision text is immutable. Load on demand:
 626                         $this->mText = $this->loadText();
 627                 }
 628                 return $this->mText;
 629         }
 630
 631         /**
 632          * @return string
 633          */
 634         public function getTimestamp() {
 635                 return wfTimestamp(TS_MW, $this->mTimestamp);
 636         }
 637
 638         /**
 639          * @return bool
 640          */
 641         public function isCurrent() {
 642                 return $this->mCurrent;
 643         }
 644
 645         /**
 646          * Get previous revision for this title
 647          * @return Revision
 648          */
 649         public function getPrevious() {
 650                 if( $this->getTitle() ) {
 651                         $prev = $this->getTitle()->getPreviousRevisionID( $this->getId() );
 652                         if( $prev ) {
 653                                 return Revision::newFromTitle( $this->getTitle(), $prev );
 654                         }
 655                 }
 656                 return null;
 657         }
 658
 659         /**
 660          * @return Revision
 661          */
 662         public function getNext() {
 663                 if( $this->getTitle() ) {
 664                         $next = $this->getTitle()->getNextRevisionID( $this->getId() );
 665                         if ( $next ) {
 666                                 return Revision::newFromTitle( $this->getTitle(), $next );
 667                         }
 668                 }
 669                 return null;
 670         }
 671
 672         /**
 673          * Get previous revision Id for this page_id
 674          * This is used to populate rev_parent_id on save
 675          * @param Database $db
 676          * @return int
 677          */
 678         private function getPreviousRevisionId( $db ) {
 679                 if( is_null( $this->mPage ) ) {
 680                         return 0;
 681                 }
 682                 # Use page_latest if ID is not given
 683                 if( !$this->mId ) {
 684                         $prevId = $db->selectField( 'page', 'page_latest',
 685                                 array( 'page_id' => $this->mPage ),
 686                                 __METHOD__ );
 687                 } else {
 688                         $prevId = $db->selectField( 'revision', 'rev_id',
 689                                 array( 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ),
 690                                 __METHOD__,
 691                                 array( 'ORDER BY' => 'rev_id DESC' ) );
 692                 }
 693                 return intval( $prevId );
 694         }
 695
 696         /**
 697           * Get revision text associated with an old or archive row
 698           * $row is usually an object from wfFetchRow(), both the flags and the text
 699           * field must be included
 700           *
 701           * @param object $row The text data
 702           * @param string $prefix table prefix (default 'old_')
 703           * @return string $text|false the text requested
 704           */
 705         public static function getRevisionText( $row, $prefix = 'old_' ) {
 706                 wfProfileIn( __METHOD__ );
 707
 708                 # Get data
 709                 $textField = $prefix . 'text';
 710                 $flagsField = $prefix . 'flags';
 711
 712                 if( isset( $row->$flagsField ) ) {
 713                         $flags = explode( ',', $row->$flagsField );
 714                 } else {
 715                         $flags = array();
 716                 }
 717
 718                 if( isset( $row->$textField ) ) {
 719                         $text = $row->$textField;
 720                 } else {
 721                         wfProfileOut( __METHOD__ );
 722                         return false;
 723                 }
 724
 725                 # Use external methods for external objects, text in table is URL-only then
 726                 if ( in_array( 'external', $flags ) ) {
 727                         $url = $text;
 728                         @list(/* $proto */, $path ) = explode( '://', $url, 2 );
 729                         if( $path == '' ) {
 730                                 wfProfileOut( __METHOD__ );
 731                                 return false;
 732                         }
 733                         $text = ExternalStore::fetchFromURL( $url );
 734                 }
 735
 736                 // If the text was fetched without an error, convert it
 737                 if ( $text !== false ) {
 738                         if( in_array( 'gzip', $flags ) ) {
 739                                 # Deal with optional compression of archived pages.
 740                                 # This can be done periodically via maintenance/compressOld.php, and
 741                                 # as pages are saved if $wgCompressRevisions is set.
 742                                 $text = gzinflate( $text );
 743                         }
 744
 745                         if( in_array( 'object', $flags ) ) {
 746                                 # Generic compressed storage
 747                                 $obj = unserialize( $text );
 748                                 if ( !is_object( $obj ) ) {
 749                                         // Invalid object
 750                                         wfProfileOut( __METHOD__ );
 751                                         return false;
 752                                 }
 753                                 $text = $obj->getText();
 754                         }
 755
 756                         global $wgLegacyEncoding;
 757                         if( $wgLegacyEncoding && !in_array( 'utf-8', $flags ) && !in_array( 'utf8', $flags ) ) {
 758                                 # Old revisions kept around in a legacy encoding?
 759                                 # Upconvert on demand.
 760                                 # ("utf8" checked for compatibility with some broken
 761                                 #  conversion scripts 2008-12-30)
 762                                 global $wgInputEncoding, $wgContLang;
 763                                 $text = $wgContLang->iconv( $wgLegacyEncoding, $wgInputEncoding, $text );
 764                         }
 765                 }
 766                 wfProfileOut( __METHOD__ );
 767                 return $text;
 768         }
 769
 770         /**
 771          * If $wgCompressRevisions is enabled, we will compress data.
 772          * The input string is modified in place.
 773          * Return value is the flags field: contains 'gzip' if the
 774          * data is compressed, and 'utf-8' if we're saving in UTF-8
 775          * mode.
 776          *
 777          * @param mixed $text reference to a text
 778          * @return string
 779          */
 780         public static function compressRevisionText( &$text ) {
 781                 global $wgCompressRevisions;
 782                 $flags = array();
 783
 784                 # Revisions not marked this way will be converted
 785                 # on load if $wgLegacyCharset is set in the future.
 786                 $flags[] = 'utf-8';
 787
 788                 if( $wgCompressRevisions ) {
 789                         if( function_exists( 'gzdeflate' ) ) {
 790                                 $text = gzdeflate( $text );
 791                                 $flags[] = 'gzip';
 792                         } else {
 793                                 wfDebug( "Revision::compressRevisionText() -- no zlib support, not compressing\n" );
 794                         }
 795                 }
 796                 return implode( ',', $flags );
 797         }
 798
 799         /**
 800          * Insert a new revision into the database, returning the new revision ID
 801          * number on success and dies horribly on failure.
 802          *
 803          * @param Database $dbw
 804          * @return int
 805          */
 806         public function insertOn( $dbw ) {
 807                 global $wgDefaultExternalStore;
 808
 809                 wfProfileIn( __METHOD__ );
 810
 811                 $data = $this->mText;
 812                 $flags = Revision::compressRevisionText( $data );
 813
 814                 # Write to external storage if required
 815                 if( $wgDefaultExternalStore ) {
 816                         // Store and get the URL
 817                         $data = ExternalStore::insertToDefault( $data );
 818                         if( !$data ) {
 819                                 throw new MWException( "Unable to store text to external storage" );
 820                         }
 821                         if( $flags ) {
 822                                 $flags .= ',';
 823                         }
 824                         $flags .= 'external';
 825                 }
 826
 827                 # Record the text (or external storage URL) to the text table
 828                 if( !isset( $this->mTextId ) ) {
 829                         $old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );
 830                         $dbw->insert( 'text',
 831                                 array(
 832                                         'old_id'    => $old_id,
 833                                         'old_text'  => $data,
 834                                         'old_flags' => $flags,
 835                                 ), __METHOD__
 836                         );
 837                         $this->mTextId = $dbw->insertId();
 838                 }
 839
 840                 # Record the edit in revisions
 841                 $rev_id = isset( $this->mId )
 842                         ? $this->mId
 843                         : $dbw->nextSequenceValue( 'revision_rev_id_seq' );
 844                 $dbw->insert( 'revision',
 845                         array(
 846                                 'rev_id'         => $rev_id,
 847                                 'rev_page'       => $this->mPage,
 848                                 'rev_text_id'    => $this->mTextId,
 849                                 'rev_comment'    => $this->mComment,
 850                                 'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
 851                                 'rev_user'       => $this->mUser,
 852                                 'rev_user_text'  => $this->mUserText,
 853                                 'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
 854                                 'rev_deleted'    => $this->mDeleted,
 855                                 'rev_len'            => $this->mSize,
 856                                 'rev_parent_id'  => is_null($this->mParentId) ?
 857                                         $this->getPreviousRevisionId( $dbw ) : $this->mParentId
 858                         ), __METHOD__
 859                 );
 860
 861                 $this->mId = !is_null( $rev_id ) ? $rev_id : $dbw->insertId();
 862
 863                 wfRunHooks( 'RevisionInsertComplete', array( &$this, $data, $flags ) );
 864
 865                 wfProfileOut( __METHOD__ );
 866                 return $this->mId;
 867         }
 868
 869         /**
 870          * Lazy-load the revision's text.
 871          * Currently hardcoded to the 'text' table storage engine.
 872          *
 873          * @return string
 874          */
 875         protected function loadText() {
 876                 wfProfileIn( __METHOD__ );
 877
 878                 // Caching may be beneficial for massive use of external storage
 879                 global $wgRevisionCacheExpiry, $wgMemc;
 880                 $textId = $this->getTextId();
 881                 $key = wfMemcKey( 'revisiontext', 'textid', $textId );
 882                 if( $wgRevisionCacheExpiry ) {
 883                         $text = $wgMemc->get( $key );
 884                         if( is_string( $text ) ) {
 885                                 wfDebug( __METHOD__ . ": got id $textId from cache\n" );
 886                                 wfProfileOut( __METHOD__ );
 887                                 return $text;
 888                         }
 889                 }
 890
 891                 // If we kept data for lazy extraction, use it now...
 892                 if ( isset( $this->mTextRow ) ) {
 893                         $row = $this->mTextRow;
 894                         $this->mTextRow = null;
 895                 } else {
 896                         $row = null;
 897                 }
 898
 899                 if( !$row ) {
 900                         // Text data is immutable; check slaves first.
 901                         $dbr = wfGetDB( DB_SLAVE );
 902                         $row = $dbr->selectRow( 'text',
 903                                 array( 'old_text', 'old_flags' ),
 904                                 array( 'old_id' => $this->getTextId() ),
 905                                 __METHOD__ );
 906                 }
 907
 908                 if( !$row && wfGetLB()->getServerCount() > 1 ) {
 909                         // Possible slave lag!
 910                         $dbw = wfGetDB( DB_MASTER );
 911                         $row = $dbw->selectRow( 'text',
 912                                 array( 'old_text', 'old_flags' ),
 913                                 array( 'old_id' => $this->getTextId() ),
 914                                 __METHOD__ );
 915                 }
 916
 917                 $text = self::getRevisionText( $row );
 918
 919                 # No negative caching -- negative hits on text rows may be due to corrupted slave servers
 920                 if( $wgRevisionCacheExpiry && $text !== false ) {
 921                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
 922                 }
 923
 924                 wfProfileOut( __METHOD__ );
 925
 926                 return $text;
 927         }
 928
 929         /**
 930          * Create a new null-revision for insertion into a page's
 931          * history. This will not re-save the text, but simply refer
 932          * to the text from the previous version.
 933          *
 934          * Such revisions can for instance identify page rename
 935          * operations and other such meta-modifications.
 936          *
 937          * @param Database $dbw
 938          * @param int      $pageId ID number of the page to read from
 939          * @param string   $summary
 940          * @param bool     $minor
 941          * @return mixed Revision, or null on error
 942          */
 943         public static function newNullRevision( $dbw, $pageId, $summary, $minor ) {
 944                 wfProfileIn( __METHOD__ );
 945
 946                 $current = $dbw->selectRow(
 947                         array( 'page', 'revision' ),
 948                         array( 'page_latest', 'rev_text_id', 'rev_len' ),
 949                         array(
 950                                 'page_id' => $pageId,
 951                                 'page_latest=rev_id',
 952                                 ),
 953                         __METHOD__ );
 954
 955                 if( $current ) {
 956                         $revision = new Revision( array(
 957                                 'page'       => $pageId,
 958                                 'comment'    => $summary,
 959                                 'minor_edit' => $minor,
 960                                 'text_id'    => $current->rev_text_id,
 961                                 'parent_id'  => $current->page_latest,
 962                                 'len'        => $current->rev_len
 963                                 ) );
 964                 } else {
 965                         $revision = null;
 966                 }
 967
 968                 wfProfileOut( __METHOD__ );
 969                 return $revision;
 970         }
 971
 972         /**
 973          * Determine if the current user is allowed to view a particular
 974          * field of this revision, if it's marked as deleted.
 975          * @param int $field one of self::DELETED_TEXT,
 976          *                          self::DELETED_COMMENT,
 977          *                          self::DELETED_USER
 978          * @return bool
 979          */
 980         public function userCan( $field ) {
 981                 return self::userCanBitfield( $this->mDeleted, $field );
 982         }
 983
 984         /**
 985          * Determine if the current user is allowed to view a particular
 986          * field of this revision, if it's marked as deleted. This is used
 987          * by various classes to avoid duplication.
 988          * @param int $bitfield (current field)
 989          * @param int $field one of self::DELETED_TEXT = File::DELETED_FILE,
 990          *                          self::DELETED_COMMENT = File::DELETED_COMMENT,
 991          *                          self::DELETED_USER = File::DELETED_USER
 992          * @return bool
 993          */
 994         public static function userCanBitfield( $bitfield, $field ) {
 995                 if( $bitfield & $field ) { // aspect is deleted
 996                         global $wgUser;
 997                         $permission = '';
 998                         if ( $bitfield & self::DELETED_RESTRICTED ) {
 999                                 $permission = 'suppressrevision';
1000                         } elseif ( $field & self::DELETED_TEXT ) {
1001                                 $permission = 'deletedtext';
1002                         } else {
1003                                 $permission = 'deletedhistory';
1004                         }
1005                         wfDebug( "Checking for $permission due to $field match on $bitfield\n" );
1006                         return $wgUser->isAllowed( $permission );
1007                 } else {
1008                         return true;
1009                 }
1010         }
1011
1012         /**
1013          * Get rev_timestamp from rev_id, without loading the rest of the row
1014          * @param Title $title
1015          * @param integer $id
1016          */
1017         static function getTimestampFromId( $title, $id ) {
1018                 $dbr = wfGetDB( DB_SLAVE );
1019                 // Casting fix for DB2
1020                 if ( $id == '' ) {
1021                         $id = 0;
1022                 }
1023                 $conds = array( 'rev_id' => $id );
1024                 $conds['rev_page'] = $title->getArticleId();
1025                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1026                 if ( $timestamp === false && wfGetLB()->getServerCount() > 1 ) {
1027                         # Not in slave, try master
1028                         $dbw = wfGetDB( DB_MASTER );
1029                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1030                 }
1031                 return wfTimestamp( TS_MW, $timestamp );
1032         }
1033
1034         /**
1035          * Get count of revisions per page...not very efficient
1036          * @param Database $db
1037          * @param int $id, page id
1038          */
1039         static function countByPageId( $db, $id ) {
1040                 $row = $db->selectRow( 'revision', 'COUNT(*) AS revCount',
1041                         array( 'rev_page' => $id ), __METHOD__ );
1042                 if( $row ) {
1043                         return $row->revCount;
1044                 }
1045                 return 0;
1046         }
1047
1048         /**
1049          * Get count of revisions per page...not very efficient
1050          * @param Database $db
1051          * @param Title $title
1052          */
1053         static function countByTitle( $db, $title ) {
1054                 $id = $title->getArticleId();
1055                 if( $id ) {
1056                         return Revision::countByPageId( $db, $id );
1057                 }
1058                 return 0;
1059         }
1060 }
1061
1062 /**
1063  * Aliases for backwards compatibility with 1.6
1064  */
1065 define( 'MW_REV_DELETED_TEXT', Revision::DELETED_TEXT );
1066 define( 'MW_REV_DELETED_COMMENT', Revision::DELETED_COMMENT );
1067 define( 'MW_REV_DELETED_USER', Revision::DELETED_USER );
1068 define( 'MW_REV_DELETED_RESTRICTED', Revision::DELETED_RESTRICTED );