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 implements IDBAccessObject {
  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         // Revision deletion constants
  49         const DELETED_TEXT = 1;
  50         const DELETED_COMMENT = 2;
  51         const DELETED_USER = 4;
  52         const DELETED_RESTRICTED = 8;
  53         const SUPPRESSED_USER = 12; // convenience
  54
  55         // Audience options for accessors
  56         const FOR_PUBLIC = 1;
  57         const FOR_THIS_USER = 2;
  58         const RAW = 3;
  59
  60         /**
  61          * Load a page revision from a given revision ID number.
  62          * Returns null if no such revision can be found.
  63          *
  64          * $flags include:
  65          *      Revision::READ_LATEST  : Select the data from the master
  66          *      Revision::READ_LOCKING : Select & lock the data from the master
  67          *
  68          * @param $id Integer
  69          * @param $flags Integer (optional)
  70          * @return Revision or null
  71          */
  72         public static function newFromId( $id, $flags = 0 ) {
  73                 return self::newFromConds( array( 'rev_id' => intval( $id ) ), $flags );
  74         }
  75
  76         /**
  77          * Load either the current, or a specified, revision
  78          * that's attached to a given title. If not attached
  79          * to that title, will return null.
  80          *
  81          * $flags include:
  82          *      Revision::READ_LATEST  : Select the data from the master
  83          *      Revision::READ_LOCKING : Select & lock the data from the master
  84          *
  85          * @param $title Title
  86          * @param $id Integer (optional)
  87          * @param $flags Integer Bitfield (optional)
  88          * @return Revision or null
  89          */
  90         public static function newFromTitle( $title, $id = 0, $flags = null ) {
  91                 $conds = array(
  92                         'page_namespace' => $title->getNamespace(),
  93                         'page_title'     => $title->getDBkey()
  94                 );
  95                 if ( $id ) {
  96                         // Use the specified ID
  97                         $conds['rev_id'] = $id;
  98                 } else {
  99                         // Use a join to get the latest revision
 100                         $conds[] = 'rev_id=page_latest';
 101                         // Callers assume this will be up-to-date
 102                         $flags = is_int( $flags ) ? $flags : self::READ_LATEST; // b/c
 103                 }
 104                 return self::newFromConds( $conds, (int)$flags );
 105         }
 106
 107         /**
 108          * Load either the current, or a specified, revision
 109          * that's attached to a given page ID.
 110          * Returns null if no such revision can be found.
 111          *
 112          * $flags include:
 113          *      Revision::READ_LATEST  : Select the data from the master
 114          *      Revision::READ_LOCKING : Select & lock the data from the master
 115          *
 116          * @param $revId Integer
 117          * @param $pageId Integer (optional)
 118          * @param $flags Integer Bitfield (optional)
 119          * @return Revision or null
 120          */
 121         public static function newFromPageId( $pageId, $revId = 0, $flags = null ) {
 122                 $conds = array( 'page_id' => $pageId );
 123                 if ( $revId ) {
 124                         $conds['rev_id'] = $revId;
 125                 } else {
 126                         // Use a join to get the latest revision
 127                         $conds[] = 'rev_id = page_latest';
 128                         // Callers assume this will be up-to-date
 129                         $flags = is_int( $flags ) ? $flags : self::READ_LATEST; // b/c
 130                 }
 131                 return self::newFromConds( $conds, (int)$flags );
 132         }
 133
 134         /**
 135          * Make a fake revision object from an archive table row. This is queried
 136          * for permissions or even inserted (as in Special:Undelete)
 137          * @todo FIXME: Should be a subclass for RevisionDelete. [TS]
 138          *
 139          * @param $row
 140          * @param $overrides array
 141          *
 142          * @throws MWException
 143          * @return Revision
 144          */
 145         public static function newFromArchiveRow( $row, $overrides = array() ) {
 146                 global $wgContentHandlerUseDB;
 147
 148                 $attribs = $overrides + array(
 149                         'page'       => isset( $row->ar_page_id ) ? $row->ar_page_id : null,
 150                         'id'         => isset( $row->ar_rev_id ) ? $row->ar_rev_id : null,
 151                         'comment'    => $row->ar_comment,
 152                         'user'       => $row->ar_user,
 153                         'user_text'  => $row->ar_user_text,
 154                         'timestamp'  => $row->ar_timestamp,
 155                         'minor_edit' => $row->ar_minor_edit,
 156                         'text_id'    => isset( $row->ar_text_id ) ? $row->ar_text_id : null,
 157                         'deleted'    => $row->ar_deleted,
 158                         'len'        => $row->ar_len,
 159                         'sha1'       => isset( $row->ar_sha1 ) ? $row->ar_sha1 : null,
 160                         'content_model'   => isset( $row->ar_content_model ) ? $row->ar_content_model : null,
 161                         'content_format'  => isset( $row->ar_content_format ) ? $row->ar_content_format : null,
 162                 );
 163
 164                 if ( !$wgContentHandlerUseDB ) {
 165                         unset( $attribs['content_model'] );
 166                         unset( $attribs['content_format'] );
 167                 }
 168
 169                 if ( isset( $row->ar_text ) && !$row->ar_text_id ) {
 170                         // Pre-1.5 ar_text row
 171                         $attribs['text'] = self::getRevisionText( $row, 'ar_' );
 172                         if ( $attribs['text'] === false ) {
 173                                 throw new MWException( 'Unable to load text from archive row (possibly bug 22624)' );
 174                         }
 175                 }
 176                 return new self( $attribs );
 177         }
 178
 179         /**
 180          * @since 1.19
 181          *
 182          * @param $row
 183          * @return Revision
 184          */
 185         public static function newFromRow( $row ) {
 186                 return new self( $row );
 187         }
 188
 189         /**
 190          * Load a page revision from a given revision ID number.
 191          * Returns null if no such revision can be found.
 192          *
 193          * @param $db DatabaseBase
 194          * @param $id Integer
 195          * @return Revision or null
 196          */
 197         public static function loadFromId( $db, $id ) {
 198                 return self::loadFromConds( $db, array( 'rev_id' => intval( $id ) ) );
 199         }
 200
 201         /**
 202          * Load either the current, or a specified, revision
 203          * that's attached to a given page. If not attached
 204          * to that page, will return null.
 205          *
 206          * @param $db DatabaseBase
 207          * @param $pageid Integer
 208          * @param $id Integer
 209          * @return Revision or null
 210          */
 211         public static function loadFromPageId( $db, $pageid, $id = 0 ) {
 212                 $conds = array( 'rev_page' => intval( $pageid ), 'page_id'  => intval( $pageid ) );
 213                 if( $id ) {
 214                         $conds['rev_id'] = intval( $id );
 215                 } else {
 216                         $conds[] = 'rev_id=page_latest';
 217                 }
 218                 return self::loadFromConds( $db, $conds );
 219         }
 220
 221         /**
 222          * Load either the current, or a specified, revision
 223          * that's attached to a given page. If not attached
 224          * to that page, will return null.
 225          *
 226          * @param $db DatabaseBase
 227          * @param $title Title
 228          * @param $id Integer
 229          * @return Revision or null
 230          */
 231         public static function loadFromTitle( $db, $title, $id = 0 ) {
 232                 if( $id ) {
 233                         $matchId = intval( $id );
 234                 } else {
 235                         $matchId = 'page_latest';
 236                 }
 237                 return self::loadFromConds( $db,
 238                         array( "rev_id=$matchId",
 239                                    'page_namespace' => $title->getNamespace(),
 240                                    'page_title'     => $title->getDBkey() )
 241                 );
 242         }
 243
 244         /**
 245          * Load the revision for the given title with the given timestamp.
 246          * WARNING: Timestamps may in some circumstances not be unique,
 247          * so this isn't the best key to use.
 248          *
 249          * @param $db DatabaseBase
 250          * @param $title Title
 251          * @param $timestamp String
 252          * @return Revision or null
 253          */
 254         public static function loadFromTimestamp( $db, $title, $timestamp ) {
 255                 return self::loadFromConds( $db,
 256                         array( 'rev_timestamp'  => $db->timestamp( $timestamp ),
 257                                    'page_namespace' => $title->getNamespace(),
 258                                    'page_title'     => $title->getDBkey() )
 259                 );
 260         }
 261
 262         /**
 263          * Given a set of conditions, fetch a revision.
 264          *
 265          * @param $conditions Array
 266          * @param $flags integer (optional)
 267          * @return Revision or null
 268          */
 269         private static function newFromConds( $conditions, $flags = 0 ) {
 270                 $db = wfGetDB( ( $flags & self::READ_LATEST ) ? DB_MASTER : DB_SLAVE );
 271                 $rev = self::loadFromConds( $db, $conditions, $flags );
 272                 if ( is_null( $rev ) && wfGetLB()->getServerCount() > 1 ) {
 273                         if ( !( $flags & self::READ_LATEST ) ) {
 274                                 $dbw = wfGetDB( DB_MASTER );
 275                                 $rev = self::loadFromConds( $dbw, $conditions, $flags );
 276                         }
 277                 }
 278                 return $rev;
 279         }
 280
 281         /**
 282          * Given a set of conditions, fetch a revision from
 283          * the given database connection.
 284          *
 285          * @param $db DatabaseBase
 286          * @param $conditions Array
 287          * @param $flags integer (optional)
 288          * @return Revision or null
 289          */
 290         private static function loadFromConds( $db, $conditions, $flags = 0 ) {
 291                 $res = self::fetchFromConds( $db, $conditions, $flags );
 292                 if( $res ) {
 293                         $row = $res->fetchObject();
 294                         if( $row ) {
 295                                 $ret = new Revision( $row );
 296                                 return $ret;
 297                         }
 298                 }
 299                 $ret = null;
 300                 return $ret;
 301         }
 302
 303         /**
 304          * Return a wrapper for a series of database rows to
 305          * fetch all of a given page's revisions in turn.
 306          * Each row can be fed to the constructor to get objects.
 307          *
 308          * @param $title Title
 309          * @return ResultWrapper
 310          */
 311         public static function fetchRevision( $title ) {
 312                 return self::fetchFromConds(
 313                         wfGetDB( DB_SLAVE ),
 314                         array( 'rev_id=page_latest',
 315                                    'page_namespace' => $title->getNamespace(),
 316                                    'page_title'     => $title->getDBkey() )
 317                 );
 318         }
 319
 320         /**
 321          * Given a set of conditions, return a ResultWrapper
 322          * which will return matching database rows with the
 323          * fields necessary to build Revision objects.
 324          *
 325          * @param $db DatabaseBase
 326          * @param $conditions Array
 327          * @param $flags integer (optional)
 328          * @return ResultWrapper
 329          */
 330         private static function fetchFromConds( $db, $conditions, $flags = 0 ) {
 331                 $fields = array_merge(
 332                         self::selectFields(),
 333                         self::selectPageFields(),
 334                         self::selectUserFields()
 335                 );
 336                 $options = array( 'LIMIT' => 1 );
 337                 if ( ( $flags & self::READ_LOCKING ) == self::READ_LOCKING ) {
 338                         $options[] = 'FOR UPDATE';
 339                 }
 340                 return $db->select(
 341                         array( 'revision', 'page', 'user' ),
 342                         $fields,
 343                         $conditions,
 344                         __METHOD__,
 345                         $options,
 346                         array( 'page' => self::pageJoinCond(), 'user' => self::userJoinCond() )
 347                 );
 348         }
 349
 350         /**
 351          * Return the value of a select() JOIN conds array for the user table.
 352          * This will get user table rows for logged-in users.
 353          * @since 1.19
 354          * @return Array
 355          */
 356         public static function userJoinCond() {
 357                 return array( 'LEFT JOIN', array( 'rev_user != 0', 'user_id = rev_user' ) );
 358         }
 359
 360         /**
 361          * Return the value of a select() page conds array for the paeg table.
 362          * This will assure that the revision(s) are not orphaned from live pages.
 363          * @since 1.19
 364          * @return Array
 365          */
 366         public static function pageJoinCond() {
 367                 return array( 'INNER JOIN', array( 'page_id = rev_page' ) );
 368         }
 369
 370         /**
 371          * Return the list of revision fields that should be selected to create
 372          * a new revision.
 373          * @return array
 374          */
 375         public static function selectFields() {
 376                 global $wgContentHandlerUseDB;
 377
 378                 $fields = array(
 379                         'rev_id',
 380                         'rev_page',
 381                         'rev_text_id',
 382                         'rev_timestamp',
 383                         'rev_comment',
 384                         'rev_user_text',
 385                         'rev_user',
 386                         'rev_minor_edit',
 387                         'rev_deleted',
 388                         'rev_len',
 389                         'rev_parent_id',
 390                         'rev_sha1',
 391                 );
 392
 393                 if ( $wgContentHandlerUseDB ) {
 394                         $fields[] = 'rev_content_format';
 395                         $fields[] = 'rev_content_model';
 396                 }
 397
 398                 return $fields;
 399         }
 400
 401         /**
 402          * Return the list of text fields that should be selected to read the
 403          * revision text
 404          * @return array
 405          */
 406         public static function selectTextFields() {
 407                 return array(
 408                         'old_text',
 409                         'old_flags'
 410                 );
 411         }
 412
 413         /**
 414          * Return the list of page fields that should be selected from page table
 415          * @return array
 416          */
 417         public static function selectPageFields() {
 418                 return array(
 419                         'page_namespace',
 420                         'page_title',
 421                         'page_id',
 422                         'page_latest',
 423                         'page_is_redirect',
 424                         'page_len',
 425                 );
 426         }
 427
 428         /**
 429          * Return the list of user fields that should be selected from user table
 430          * @return array
 431          */
 432         public static function selectUserFields() {
 433                 return array( 'user_name' );
 434         }
 435
 436         /**
 437          * Do a batched query to get the parent revision lengths
 438          * @param $db DatabaseBase
 439          * @param $revIds Array
 440          * @return array
 441          */
 442         public static function getParentLengths( $db, array $revIds ) {
 443                 $revLens = array();
 444                 if ( !$revIds ) {
 445                         return $revLens; // empty
 446                 }
 447                 wfProfileIn( __METHOD__ );
 448                 $res = $db->select( 'revision',
 449                         array( 'rev_id', 'rev_len' ),
 450                         array( 'rev_id' => $revIds ),
 451                         __METHOD__ );
 452                 foreach ( $res as $row ) {
 453                         $revLens[$row->rev_id] = $row->rev_len;
 454                 }
 455                 wfProfileOut( __METHOD__ );
 456                 return $revLens;
 457         }
 458
 459         /**
 460          * Constructor
 461          *
 462          * @param $row Mixed: either a database row or an array
 463          * @throws MWException
 464          * @access private
 465          */
 466         function __construct( $row ) {
 467                 if( is_object( $row ) ) {
 468                         $this->mId        = intval( $row->rev_id );
 469                         $this->mPage      = intval( $row->rev_page );
 470                         $this->mTextId    = intval( $row->rev_text_id );
 471                         $this->mComment   =         $row->rev_comment;
 472                         $this->mUser      = intval( $row->rev_user );
 473                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 474                         $this->mTimestamp =         $row->rev_timestamp;
 475                         $this->mDeleted   = intval( $row->rev_deleted );
 476
 477                         if( !isset( $row->rev_parent_id ) ) {
 478                                 $this->mParentId = is_null( $row->rev_parent_id ) ? null : 0;
 479                         } else {
 480                                 $this->mParentId  = intval( $row->rev_parent_id );
 481                         }
 482
 483                         if( !isset( $row->rev_len ) || is_null( $row->rev_len ) ) {
 484                                 $this->mSize = null;
 485                         } else {
 486                                 $this->mSize = intval( $row->rev_len );
 487                         }
 488
 489                         if ( !isset( $row->rev_sha1 ) ) {
 490                                 $this->mSha1 = null;
 491                         } else {
 492                                 $this->mSha1 = $row->rev_sha1;
 493                         }
 494
 495                         if( isset( $row->page_latest ) ) {
 496                                 $this->mCurrent = ( $row->rev_id == $row->page_latest );
 497                                 $this->mTitle = Title::newFromRow( $row );
 498                         } else {
 499                                 $this->mCurrent = false;
 500                                 $this->mTitle = null;
 501                         }
 502
 503                         if( !isset( $row->rev_content_model ) || is_null( $row->rev_content_model ) ) {
 504                                 $this->mContentModel = null; # determine on demand if needed
 505                         } else {
 506                                 $this->mContentModel = strval( $row->rev_content_model );
 507                         }
 508
 509                         if( !isset( $row->rev_content_format ) || is_null( $row->rev_content_format ) ) {
 510                                 $this->mContentFormat = null; # determine on demand if needed
 511                         } else {
 512                                 $this->mContentFormat = strval( $row->rev_content_format );
 513                         }
 514
 515                         // Lazy extraction...
 516                         $this->mText      = null;
 517                         if( isset( $row->old_text ) ) {
 518                                 $this->mTextRow = $row;
 519                         } else {
 520                                 // 'text' table row entry will be lazy-loaded
 521                                 $this->mTextRow = null;
 522                         }
 523
 524                         // Use user_name for users and rev_user_text for IPs...
 525                         $this->mUserText = null; // lazy load if left null
 526                         if ( $this->mUser == 0 ) {
 527                                 $this->mUserText = $row->rev_user_text; // IP user
 528                         } elseif ( isset( $row->user_name ) ) {
 529                                 $this->mUserText = $row->user_name; // logged-in user
 530                         }
 531                         $this->mOrigUserText = $row->rev_user_text;
 532                 } elseif( is_array( $row ) ) {
 533                         // Build a new revision to be saved...
 534                         global $wgUser; // ugh
 535
 536
 537                         # if we have a content object, use it to set the model and type
 538                         if ( !empty( $row['content'] ) ) {
 539                                 //@todo: when is that set? test with external store setup! check out insertOn() [dk]
 540                                 if ( !empty( $row['text_id'] ) ) {
 541                                         throw new MWException( "Text already stored in external store (id {$row['text_id']}), "
 542                                                                                         . "can't serialize content object" );
 543                                 }
 544
 545                                 $row['content_model'] = $row['content']->getModel();
 546                                 # note: mContentFormat is initializes later accordingly
 547                                 # note: content is serialized later in this method!
 548                                 # also set text to null?
 549                         }
 550
 551                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 552                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 553                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 554                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 555                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 556                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 557                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestampNow();
 558                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 559                         $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
 560                         $this->mParentId  = isset( $row['parent_id']  ) ? intval( $row['parent_id']  ) : null;
 561                         $this->mSha1      = isset( $row['sha1']  )      ? strval( $row['sha1']  )      : null;
 562
 563                         $this->mContentModel   = isset( $row['content_model']  )  ? strval( $row['content_model'] )  : null;
 564                         $this->mContentFormat  = isset( $row['content_format']  ) ? strval( $row['content_format'] ) : null;
 565
 566                         // Enforce spacing trimming on supplied text
 567                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 568                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 569                         $this->mTextRow   = null;
 570
 571                         $this->mTitle     = isset( $row['title']      ) ? $row['title'] : null;
 572
 573                         // if we have a Content object, override mText and mContentModel
 574                         if ( !empty( $row['content'] ) ) {
 575                                 if ( !( $row['content'] instanceof Content ) ) {
 576                                         throw new MWException( '`content` field must contain a Content object.' );
 577                                 }
 578
 579                                 $handler = $this->getContentHandler();
 580                                 $this->mContent = $row['content'];
 581
 582                                 $this->mContentModel = $this->mContent->getModel();
 583                                 $this->mContentHandler = null;
 584
 585                                 $this->mText = $handler->serializeContent( $row['content'], $this->getContentFormat() );
 586                         } elseif ( !is_null( $this->mText ) ) {
 587                                 $handler = $this->getContentHandler();
 588                                 $this->mContent = $handler->unserializeContent( $this->mText );
 589                         }
 590
 591                         // if we have a Title object, override mPage. Useful for testing and convenience.
 592                         if ( isset( $row['title'] ) ) {
 593                                 $this->mTitle     = $row['title'];
 594                                 $this->mPage      = $this->mTitle->getArticleID();
 595                         } else {
 596                                 $this->mTitle     = null; // Load on demand if needed
 597                         }
 598
 599                         // @todo: XXX: really? we are about to create a revision. it will usually then be the current one.
 600                         $this->mCurrent   = false;
 601
 602                         // If we still have no length, see it we have the text to figure it out
 603                         if ( !$this->mSize ) {
 604                                 if ( !is_null( $this->mContent ) ) {
 605                                         $this->mSize = $this->mContent->getSize();
 606                                 } else {
 607                                         #NOTE: this should never happen if we have either text or content object!
 608                                         $this->mSize = null;
 609                                 }
 610                         }
 611
 612                         // Same for sha1
 613                         if ( $this->mSha1 === null ) {
 614                                 $this->mSha1 = is_null( $this->mText ) ? null : self::base36Sha1( $this->mText );
 615                         }
 616
 617                         // force lazy init
 618                         $this->getContentModel();
 619                         $this->getContentFormat();
 620                 } else {
 621                         throw new MWException( 'Revision constructor passed invalid row format.' );
 622                 }
 623                 $this->mUnpatrolled = null;
 624         }
 625
 626         /**
 627          * Get revision ID
 628          *
 629          * @return Integer|null
 630          */
 631         public function getId() {
 632                 return $this->mId;
 633         }
 634
 635         /**
 636          * Set the revision ID
 637          *
 638          * @since 1.19
 639          * @param $id Integer
 640          */
 641         public function setId( $id ) {
 642                 $this->mId = $id;
 643         }
 644
 645         /**
 646          * Get text row ID
 647          *
 648          * @return Integer|null
 649          */
 650         public function getTextId() {
 651                 return $this->mTextId;
 652         }
 653
 654         /**
 655          * Get parent revision ID (the original previous page revision)
 656          *
 657          * @return Integer|null
 658          */
 659         public function getParentId() {
 660                 return $this->mParentId;
 661         }
 662
 663         /**
 664          * Returns the length of the text in this revision, or null if unknown.
 665          *
 666          * @return Integer|null
 667          */
 668         public function getSize() {
 669                 return $this->mSize;
 670         }
 671
 672         /**
 673          * Returns the base36 sha1 of the text in this revision, or null if unknown.
 674          *
 675          * @return String|null
 676          */
 677         public function getSha1() {
 678                 return $this->mSha1;
 679         }
 680
 681         /**
 682          * Returns the title of the page associated with this entry or null.
 683          *
 684          * Will do a query, when title is not set and id is given.
 685          *
 686          * @return Title|null
 687          */
 688         public function getTitle() {
 689                 if( isset( $this->mTitle ) ) {
 690                         return $this->mTitle;
 691                 }
 692                 if( !is_null( $this->mId ) ) { //rev_id is defined as NOT NULL, but this revision may not yet have been inserted.
 693                         $dbr = wfGetDB( DB_SLAVE );
 694                         $row = $dbr->selectRow(
 695                                 array( 'page', 'revision' ),
 696                                 self::selectPageFields(),
 697                                 array( 'page_id=rev_page',
 698                                            'rev_id' => $this->mId ),
 699                                 __METHOD__ );
 700                         if ( $row ) {
 701                                 $this->mTitle = Title::newFromRow( $row );
 702                         }
 703                 }
 704
 705                 if ( !$this->mTitle && !is_null( $this->mPage ) && $this->mPage > 0 ) {
 706                         $this->mTitle = Title::newFromID( $this->mPage );
 707                 }
 708
 709                 return $this->mTitle;
 710         }
 711
 712         /**
 713          * Set the title of the revision
 714          *
 715          * @param $title Title
 716          */
 717         public function setTitle( $title ) {
 718                 $this->mTitle = $title;
 719         }
 720
 721         /**
 722          * Get the page ID
 723          *
 724          * @return Integer|null
 725          */
 726         public function getPage() {
 727                 return $this->mPage;
 728         }
 729
 730         /**
 731          * Fetch revision's user id if it's available to the specified audience.
 732          * If the specified audience does not have access to it, zero will be
 733          * returned.
 734          *
 735          * @param $audience Integer: one of:
 736          *      Revision::FOR_PUBLIC       to be displayed to all users
 737          *      Revision::FOR_THIS_USER    to be displayed to the given user
 738          *      Revision::RAW              get the ID regardless of permissions
 739          * @param $user User object to check for, only if FOR_THIS_USER is passed
 740          *              to the $audience parameter
 741          * @return Integer
 742          */
 743         public function getUser( $audience = self::FOR_PUBLIC, User $user = null ) {
 744                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 745                         return 0;
 746                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
 747                         return 0;
 748                 } else {
 749                         return $this->mUser;
 750                 }
 751         }
 752
 753         /**
 754          * Fetch revision's user id without regard for the current user's permissions
 755          *
 756          * @return String
 757          */
 758         public function getRawUser() {
 759                 return $this->mUser;
 760         }
 761
 762         /**
 763          * Fetch revision's username if it's available to the specified audience.
 764          * If the specified audience does not have access to the username, an
 765          * empty string will be returned.
 766          *
 767          * @param $audience Integer: one of:
 768          *      Revision::FOR_PUBLIC       to be displayed to all users
 769          *      Revision::FOR_THIS_USER    to be displayed to the given user
 770          *      Revision::RAW              get the text regardless of permissions
 771          * @param $user User object to check for, only if FOR_THIS_USER is passed
 772          *              to the $audience parameter
 773          * @return string
 774          */
 775         public function getUserText( $audience = self::FOR_PUBLIC, User $user = null ) {
 776                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 777                         return '';
 778                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
 779                         return '';
 780                 } else {
 781                         return $this->getRawUserText();
 782                 }
 783         }
 784
 785         /**
 786          * Fetch revision's username without regard for view restrictions
 787          *
 788          * @return String
 789          */
 790         public function getRawUserText() {
 791                 if ( $this->mUserText === null ) {
 792                         $this->mUserText = User::whoIs( $this->mUser ); // load on demand
 793                         if ( $this->mUserText === false ) {
 794                                 # This shouldn't happen, but it can if the wiki was recovered
 795                                 # via importing revs and there is no user table entry yet.
 796                                 $this->mUserText = $this->mOrigUserText;
 797                         }
 798                 }
 799                 return $this->mUserText;
 800         }
 801
 802         /**
 803          * Fetch revision comment if it's available to the specified audience.
 804          * If the specified audience does not have access to the comment, an
 805          * empty string will be returned.
 806          *
 807          * @param $audience Integer: one of:
 808          *      Revision::FOR_PUBLIC       to be displayed to all users
 809          *      Revision::FOR_THIS_USER    to be displayed to the given user
 810          *      Revision::RAW              get the text regardless of permissions
 811          * @param $user User object to check for, only if FOR_THIS_USER is passed
 812          *              to the $audience parameter
 813          * @return String
 814          */
 815         function getComment( $audience = self::FOR_PUBLIC, User $user = null ) {
 816                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_COMMENT ) ) {
 817                         return '';
 818                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_COMMENT, $user ) ) {
 819                         return '';
 820                 } else {
 821                         return $this->mComment;
 822                 }
 823         }
 824
 825         /**
 826          * Fetch revision comment without regard for the current user's permissions
 827          *
 828          * @return String
 829          */
 830         public function getRawComment() {
 831                 return $this->mComment;
 832         }
 833
 834         /**
 835          * @return Boolean
 836          */
 837         public function isMinor() {
 838                 return (bool)$this->mMinorEdit;
 839         }
 840
 841         /**
 842          * @return Integer rcid of the unpatrolled row, zero if there isn't one
 843          */
 844         public function isUnpatrolled() {
 845                 if( $this->mUnpatrolled !== null ) {
 846                         return $this->mUnpatrolled;
 847                 }
 848                 $dbr = wfGetDB( DB_SLAVE );
 849                 $this->mUnpatrolled = $dbr->selectField( 'recentchanges',
 850                         'rc_id',
 851                         array( // Add redundant user,timestamp condition so we can use the existing index
 852                                 'rc_user_text'  => $this->getRawUserText(),
 853                                 'rc_timestamp'  => $dbr->timestamp( $this->getTimestamp() ),
 854                                 'rc_this_oldid' => $this->getId(),
 855                                 'rc_patrolled'  => 0
 856                         ),
 857                         __METHOD__
 858                 );
 859                 return (int)$this->mUnpatrolled;
 860         }
 861
 862         /**
 863          * @param $field int one of DELETED_* bitfield constants
 864          *
 865          * @return Boolean
 866          */
 867         public function isDeleted( $field ) {
 868                 return ( $this->mDeleted & $field ) == $field;
 869         }
 870
 871         /**
 872          * Get the deletion bitfield of the revision
 873          *
 874          * @return int
 875          */
 876         public function getVisibility() {
 877                 return (int)$this->mDeleted;
 878         }
 879
 880         /**
 881          * Fetch revision text if it's available to the specified audience.
 882          * If the specified audience does not have the ability to view this
 883          * revision, an empty string will be returned.
 884          *
 885          * @param $audience Integer: one of:
 886          *      Revision::FOR_PUBLIC       to be displayed to all users
 887          *      Revision::FOR_THIS_USER    to be displayed to the given user
 888          *      Revision::RAW              get the text regardless of permissions
 889          * @param $user User object to check for, only if FOR_THIS_USER is passed
 890          *              to the $audience parameter
 891          *
 892          * @deprecated in 1.21, use getContent() instead
 893          * @todo: replace usage in core
 894          * @return String
 895          */
 896         public function getText( $audience = self::FOR_PUBLIC, User $user = null ) {
 897                 wfDeprecated( __METHOD__, '1.21' );
 898
 899                 $content = $this->getContent( $audience, $user );
 900                 return ContentHandler::getContentText( $content ); # returns the raw content text, if applicable
 901         }
 902
 903         /**
 904          * Fetch revision content if it's available to the specified audience.
 905          * If the specified audience does not have the ability to view this
 906          * revision, null will be returned.
 907          *
 908          * @param $audience Integer: one of:
 909          *      Revision::FOR_PUBLIC       to be displayed to all users
 910          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 911          *      Revision::RAW              get the text regardless of permissions
 912          * @param $user User object to check for, only if FOR_THIS_USER is passed
 913          *              to the $audience parameter
 914          * @since 1.21
 915          * @return Content
 916          */
 917         public function getContent( $audience = self::FOR_PUBLIC, User $user = null ) {
 918                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_TEXT ) ) {
 919                         return null;
 920                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_TEXT, $user ) ) {
 921                         return null;
 922                 } else {
 923                         return $this->getContentInternal();
 924                 }
 925         }
 926
 927         /**
 928          * Alias for getText(Revision::FOR_THIS_USER)
 929          *
 930          * @deprecated since 1.17
 931          * @return String
 932          */
 933         public function revText() {
 934                 wfDeprecated( __METHOD__, '1.17' );
 935                 return $this->getText( self::FOR_THIS_USER );
 936         }
 937
 938         /**
 939          * Fetch revision text without regard for view restrictions
 940          *
 941          * @return String
 942          *
 943          * @deprecated since 1.21. Instead, use Revision::getContent( Revision::RAW )
 944          *                         or Revision::getSerializedData() as appropriate.
 945          */
 946         public function getRawText() {
 947                 wfDeprecated( __METHOD__, "1.21" );
 948
 949                 return $this->getText( self::RAW );
 950         }
 951
 952         /**
 953          * Fetch original serialized data without regard for view restrictions
 954          *
 955          * @since 1.21
 956          * @return String
 957          */
 958         public function getSerializedData() {
 959                 return $this->mText;
 960         }
 961
 962         /**
 963          * Gets the content object for the revision
 964          *
 965          * @since 1.21
 966          * @return Content
 967          */
 968         protected function getContentInternal() {
 969                 if( is_null( $this->mContent ) ) {
 970                         // Revision is immutable. Load on demand:
 971
 972                         $handler = $this->getContentHandler();
 973                         $format = $this->getContentFormat();
 974                         $title = $this->getTitle();
 975
 976                         if( is_null( $this->mText ) ) {
 977                                 // Load text on demand:
 978                                 $this->mText = $this->loadText();
 979                         }
 980
 981                         $this->mContent = is_null( $this->mText ) ? null : $handler->unserializeContent( $this->mText, $format );
 982                 }
 983
 984                 return $this->mContent->copy(); // NOTE: copy() will return $this for immutable content objects
 985         }
 986
 987         /**
 988          * Returns the content model for this revision.
 989          *
 990          * If no content model was stored in the database, $this->getTitle()->getContentModel() is
 991          * used to determine the content model to use. If no title is know, CONTENT_MODEL_WIKITEXT
 992          * is used as a last resort.
 993          *
 994          * @return String the content model id associated with this revision, see the CONTENT_MODEL_XXX constants.
 995          **/
 996         public function getContentModel() {
 997                 if ( !$this->mContentModel ) {
 998                         $title = $this->getTitle();
 999                         $this->mContentModel = ( $title ? $title->getContentModel() : CONTENT_MODEL_WIKITEXT );
1000
1001                         assert( !empty( $this->mContentModel ) );
1002                 }
1003
1004                 return $this->mContentModel;
1005         }
1006
1007         /**
1008          * Returns the content format for this revision.
1009          *
1010          * If no content format was stored in the database, the default format for this
1011          * revision's content model is returned.
1012          *
1013          * @return String the content format id associated with this revision, see the CONTENT_FORMAT_XXX constants.
1014          **/
1015         public function getContentFormat() {
1016                 if ( !$this->mContentFormat ) {
1017                         $handler = $this->getContentHandler();
1018                         $this->mContentFormat = $handler->getDefaultFormat();
1019
1020                         assert( !empty( $this->mContentFormat ) );
1021                 }
1022
1023                 return $this->mContentFormat;
1024         }
1025
1026         /**
1027          * Returns the content handler appropriate for this revision's content model.
1028          *
1029          * @return ContentHandler
1030          */
1031         public function getContentHandler() {
1032                 if ( !$this->mContentHandler ) {
1033                         $model = $this->getContentModel();
1034                         $this->mContentHandler = ContentHandler::getForModelID( $model );
1035
1036                         $format = $this->getContentFormat();
1037
1038                         if ( !$this->mContentHandler->isSupportedFormat( $format ) ) {
1039                                 throw new MWException( "Oops, the content format $format is not supported for this content model, $model" );
1040                         }
1041                 }
1042
1043                 return $this->mContentHandler;
1044         }
1045
1046         /**
1047          * @return String
1048          */
1049         public function getTimestamp() {
1050                 return wfTimestamp( TS_MW, $this->mTimestamp );
1051         }
1052
1053         /**
1054          * @return Boolean
1055          */
1056         public function isCurrent() {
1057                 return $this->mCurrent;
1058         }
1059
1060         /**
1061          * Get previous revision for this title
1062          *
1063          * @return Revision or null
1064          */
1065         public function getPrevious() {
1066                 if( $this->getTitle() ) {
1067                         $prev = $this->getTitle()->getPreviousRevisionID( $this->getId() );
1068                         if( $prev ) {
1069                                 return self::newFromTitle( $this->getTitle(), $prev );
1070                         }
1071                 }
1072                 return null;
1073         }
1074
1075         /**
1076          * Get next revision for this title
1077          *
1078          * @return Revision or null
1079          */
1080         public function getNext() {
1081                 if( $this->getTitle() ) {
1082                         $next = $this->getTitle()->getNextRevisionID( $this->getId() );
1083                         if ( $next ) {
1084                                 return self::newFromTitle( $this->getTitle(), $next );
1085                         }
1086                 }
1087                 return null;
1088         }
1089
1090         /**
1091          * Get previous revision Id for this page_id
1092          * This is used to populate rev_parent_id on save
1093          *
1094          * @param $db DatabaseBase
1095          * @return Integer
1096          */
1097         private function getPreviousRevisionId( $db ) {
1098                 if( is_null( $this->mPage ) ) {
1099                         return 0;
1100                 }
1101                 # Use page_latest if ID is not given
1102                 if( !$this->mId ) {
1103                         $prevId = $db->selectField( 'page', 'page_latest',
1104                                 array( 'page_id' => $this->mPage ),
1105                                 __METHOD__ );
1106                 } else {
1107                         $prevId = $db->selectField( 'revision', 'rev_id',
1108                                 array( 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ),
1109                                 __METHOD__,
1110                                 array( 'ORDER BY' => 'rev_id DESC' ) );
1111                 }
1112                 return intval( $prevId );
1113         }
1114
1115         /**
1116           * Get revision text associated with an old or archive row
1117           * $row is usually an object from wfFetchRow(), both the flags and the text
1118           * field must be included
1119           *
1120           * @param $row Object: the text data
1121           * @param $prefix String: table prefix (default 'old_')
1122           * @return String: text the text requested or false on failure
1123           */
1124         public static function getRevisionText( $row, $prefix = 'old_' ) {
1125                 wfProfileIn( __METHOD__ );
1126
1127                 # Get data
1128                 $textField = $prefix . 'text';
1129                 $flagsField = $prefix . 'flags';
1130
1131                 if( isset( $row->$flagsField ) ) {
1132                         $flags = explode( ',', $row->$flagsField );
1133                 } else {
1134                         $flags = array();
1135                 }
1136
1137                 if( isset( $row->$textField ) ) {
1138                         $text = $row->$textField;
1139                 } else {
1140                         wfProfileOut( __METHOD__ );
1141                         return false;
1142                 }
1143
1144                 # Use external methods for external objects, text in table is URL-only then
1145                 if ( in_array( 'external', $flags ) ) {
1146                         $url = $text;
1147                         $parts = explode( '://', $url, 2 );
1148                         if( count( $parts ) == 1 || $parts[1] == '' ) {
1149                                 wfProfileOut( __METHOD__ );
1150                                 return false;
1151                         }
1152                         $text = ExternalStore::fetchFromURL( $url );
1153                 }
1154
1155                 // If the text was fetched without an error, convert it
1156                 if ( $text !== false ) {
1157                         if( in_array( 'gzip', $flags ) ) {
1158                                 # Deal with optional compression of archived pages.
1159                                 # This can be done periodically via maintenance/compressOld.php, and
1160                                 # as pages are saved if $wgCompressRevisions is set.
1161                                 $text = gzinflate( $text );
1162                         }
1163
1164                         if( in_array( 'object', $flags ) ) {
1165                                 # Generic compressed storage
1166                                 $obj = unserialize( $text );
1167                                 if ( !is_object( $obj ) ) {
1168                                         // Invalid object
1169                                         wfProfileOut( __METHOD__ );
1170                                         return false;
1171                                 }
1172                                 $text = $obj->getText();
1173                         }
1174
1175                         global $wgLegacyEncoding;
1176                         if( $text !== false && $wgLegacyEncoding
1177                                 && !in_array( 'utf-8', $flags ) && !in_array( 'utf8', $flags ) )
1178                         {
1179                                 # Old revisions kept around in a legacy encoding?
1180                                 # Upconvert on demand.
1181                                 # ("utf8" checked for compatibility with some broken
1182                                 #  conversion scripts 2008-12-30)
1183                                 global $wgContLang;
1184                                 $text = $wgContLang->iconv( $wgLegacyEncoding, 'UTF-8', $text );
1185                         }
1186                 }
1187                 wfProfileOut( __METHOD__ );
1188                 return $text;
1189         }
1190
1191         /**
1192          * If $wgCompressRevisions is enabled, we will compress data.
1193          * The input string is modified in place.
1194          * Return value is the flags field: contains 'gzip' if the
1195          * data is compressed, and 'utf-8' if we're saving in UTF-8
1196          * mode.
1197          *
1198          * @param $text Mixed: reference to a text
1199          * @return String
1200          */
1201         public static function compressRevisionText( &$text ) {
1202                 global $wgCompressRevisions;
1203                 $flags = array();
1204
1205                 # Revisions not marked this way will be converted
1206                 # on load if $wgLegacyCharset is set in the future.
1207                 $flags[] = 'utf-8';
1208
1209                 if( $wgCompressRevisions ) {
1210                         if( function_exists( 'gzdeflate' ) ) {
1211                                 $text = gzdeflate( $text );
1212                                 $flags[] = 'gzip';
1213                         } else {
1214                                 wfDebug( __METHOD__ . " -- no zlib support, not compressing\n" );
1215                         }
1216                 }
1217                 return implode( ',', $flags );
1218         }
1219
1220         /**
1221          * Insert a new revision into the database, returning the new revision ID
1222          * number on success and dies horribly on failure.
1223          *
1224          * @param $dbw DatabaseBase: (master connection)
1225          * @throws MWException
1226          * @return Integer
1227          */
1228         public function insertOn( $dbw ) {
1229                 global $wgDefaultExternalStore, $wgContentHandlerUseDB;
1230
1231                 wfProfileIn( __METHOD__ );
1232
1233                 $this->checkContentModel();
1234
1235                 $data = $this->mText;
1236                 $flags = self::compressRevisionText( $data );
1237
1238                 # Write to external storage if required
1239                 if( $wgDefaultExternalStore ) {
1240                         // Store and get the URL
1241                         $data = ExternalStore::insertToDefault( $data );
1242                         if( !$data ) {
1243                                 throw new MWException( "Unable to store text to external storage" );
1244                         }
1245                         if( $flags ) {
1246                                 $flags .= ',';
1247                         }
1248                         $flags .= 'external';
1249                 }
1250
1251                 # Record the text (or external storage URL) to the text table
1252                 if( !isset( $this->mTextId ) ) {
1253                         $old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );
1254                         $dbw->insert( 'text',
1255                                 array(
1256                                         'old_id'    => $old_id,
1257                                         'old_text'  => $data,
1258                                         'old_flags' => $flags,
1259                                 ), __METHOD__
1260                         );
1261                         $this->mTextId = $dbw->insertId();
1262                 }
1263
1264                 if ( $this->mComment === null ) $this->mComment = "";
1265
1266                 # Record the edit in revisions
1267                 $rev_id = isset( $this->mId )
1268                         ? $this->mId
1269                         : $dbw->nextSequenceValue( 'revision_rev_id_seq' );
1270                 $row = array(
1271                         'rev_id'         => $rev_id,
1272                         'rev_page'       => $this->mPage,
1273                         'rev_text_id'    => $this->mTextId,
1274                         'rev_comment'    => $this->mComment,
1275                         'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
1276                         'rev_user'       => $this->mUser,
1277                         'rev_user_text'  => $this->mUserText,
1278                         'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
1279                         'rev_deleted'    => $this->mDeleted,
1280                         'rev_len'        => $this->mSize,
1281                         'rev_parent_id'  => is_null( $this->mParentId )
1282                                 ? $this->getPreviousRevisionId( $dbw )
1283                                 : $this->mParentId,
1284                         'rev_sha1'       => is_null( $this->mSha1 )
1285                                 ? Revision::base36Sha1( $this->mText )
1286                                 : $this->mSha1,
1287                 );
1288
1289                 if ( $wgContentHandlerUseDB ) {
1290                         //NOTE: Store null for the default model and format, to save space.
1291                         //XXX: Makes the DB sensitive to changed defaults. Make this behaviour optional? Only in miser mode?
1292
1293                         $model = $this->getContentModel();
1294                         $format = $this->getContentFormat();
1295
1296                         $title = $this->getTitle();
1297
1298                         if ( $title === null ) {
1299                                 throw new MWException( "Insufficient information to determine the title of the revision's page!" );
1300                         }
1301
1302                         $defaultModel = ContentHandler::getDefaultModelFor( $title );
1303                         $defaultFormat = ContentHandler::getForModelID( $defaultModel )->getDefaultFormat();
1304
1305                         $row[ 'rev_content_model' ] = ( $model === $defaultModel ) ? null : $model;
1306                         $row[ 'rev_content_format' ] = ( $format === $defaultFormat ) ? null : $format;
1307                 }
1308
1309                 $dbw->insert( 'revision', $row, __METHOD__ );
1310
1311                 $this->mId = !is_null( $rev_id ) ? $rev_id : $dbw->insertId();
1312
1313                 wfRunHooks( 'RevisionInsertComplete', array( &$this, $data, $flags ) );
1314
1315                 wfProfileOut( __METHOD__ );
1316                 return $this->mId;
1317         }
1318
1319         protected function checkContentModel() {
1320                 global $wgContentHandlerUseDB;
1321
1322                 $title = $this->getTitle(); //note: may return null for revisions that have not yet been inserted.
1323
1324                 $model = $this->getContentModel();
1325                 $format = $this->getContentFormat();
1326                 $handler = $this->getContentHandler();
1327
1328                 if ( !$handler->isSupportedFormat( $format ) ) {
1329                         $t = $title->getPrefixedDBkey();
1330
1331                         throw new MWException( "Can't use format $format with content model $model on $t" );
1332                 }
1333
1334                 if ( !$wgContentHandlerUseDB && $title ) {
1335                         // if $wgContentHandlerUseDB is not set, all revisions must use the default content model and format.
1336
1337                         $defaultModel = ContentHandler::getDefaultModelFor( $title );
1338                         $defaultHandler = ContentHandler::getForModelID( $defaultModel );
1339                         $defaultFormat = $defaultHandler->getDefaultFormat();
1340
1341                         if ( $this->getContentModel() != $defaultModel ) {
1342                                 $t = $title->getPrefixedDBkey();
1343
1344                                 throw new MWException( "Can't save non-default content model with \$wgContentHandlerUseDB disabled: "
1345                                                                                 . "model is $model , default for $t is $defaultModel" );
1346                         }
1347
1348                         if ( $this->getContentFormat() != $defaultFormat ) {
1349                                 $t = $title->getPrefixedDBkey();
1350
1351                                 throw new MWException( "Can't use non-default content format with \$wgContentHandlerUseDB disabled: "
1352                                                                                 . "format is $format, default for $t is $defaultFormat" );
1353                         }
1354                 }
1355
1356                 $content = $this->getContent( Revision::RAW );
1357
1358                 if ( !$content->isValid() ) {
1359                         $t = $title->getPrefixedDBkey();
1360
1361                         throw new MWException( "Content of $t is not valid! Content model is $model" );
1362                 }
1363         }
1364
1365         /**
1366          * Get the base 36 SHA-1 value for a string of text
1367          * @param $text String
1368          * @return String
1369          */
1370         public static function base36Sha1( $text ) {
1371                 return wfBaseConvert( sha1( $text ), 16, 36, 31 );
1372         }
1373
1374         /**
1375          * Lazy-load the revision's text.
1376          * Currently hardcoded to the 'text' table storage engine.
1377          *
1378          * @return String
1379          */
1380         protected function loadText() {
1381                 wfProfileIn( __METHOD__ );
1382
1383                 // Caching may be beneficial for massive use of external storage
1384                 global $wgRevisionCacheExpiry, $wgMemc;
1385                 $textId = $this->getTextId();
1386                 $key = wfMemcKey( 'revisiontext', 'textid', $textId );
1387                 if( $wgRevisionCacheExpiry ) {
1388                         $text = $wgMemc->get( $key );
1389                         if( is_string( $text ) ) {
1390                                 wfDebug( __METHOD__ . ": got id $textId from cache\n" );
1391                                 wfProfileOut( __METHOD__ );
1392                                 return $text;
1393                         }
1394                 }
1395
1396                 // If we kept data for lazy extraction, use it now...
1397                 if ( isset( $this->mTextRow ) ) {
1398                         $row = $this->mTextRow;
1399                         $this->mTextRow = null;
1400                 } else {
1401                         $row = null;
1402                 }
1403
1404                 if( !$row ) {
1405                         // Text data is immutable; check slaves first.
1406                         $dbr = wfGetDB( DB_SLAVE );
1407                         $row = $dbr->selectRow( 'text',
1408                                 array( 'old_text', 'old_flags' ),
1409                                 array( 'old_id' => $this->getTextId() ),
1410                                 __METHOD__ );
1411                 }
1412
1413                 if( !$row && wfGetLB()->getServerCount() > 1 ) {
1414                         // Possible slave lag!
1415                         $dbw = wfGetDB( DB_MASTER );
1416                         $row = $dbw->selectRow( 'text',
1417                                 array( 'old_text', 'old_flags' ),
1418                                 array( 'old_id' => $this->getTextId() ),
1419                                 __METHOD__ );
1420                 }
1421
1422                 $text = self::getRevisionText( $row );
1423
1424                 # No negative caching -- negative hits on text rows may be due to corrupted slave servers
1425                 if( $wgRevisionCacheExpiry && $text !== false ) {
1426                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
1427                 }
1428
1429                 wfProfileOut( __METHOD__ );
1430
1431                 return $text;
1432         }
1433
1434         /**
1435          * Create a new null-revision for insertion into a page's
1436          * history. This will not re-save the text, but simply refer
1437          * to the text from the previous version.
1438          *
1439          * Such revisions can for instance identify page rename
1440          * operations and other such meta-modifications.
1441          *
1442          * @param $dbw DatabaseBase
1443          * @param $pageId Integer: ID number of the page to read from
1444          * @param $summary String: revision's summary
1445          * @param $minor Boolean: whether the revision should be considered as minor
1446          * @return Revision|null on error
1447          */
1448         public static function newNullRevision( $dbw, $pageId, $summary, $minor ) {
1449                 global $wgContentHandlerUseDB;
1450
1451                 wfProfileIn( __METHOD__ );
1452
1453                 $fields = array( 'page_latest', 'page_namespace', 'page_title',
1454                                                 'rev_text_id', 'rev_len', 'rev_sha1' );
1455
1456                 if ( $wgContentHandlerUseDB ) {
1457                         $fields[] = 'rev_content_model';
1458                         $fields[] = 'rev_content_format';
1459                 }
1460
1461                 $current = $dbw->selectRow(
1462                         array( 'page', 'revision' ),
1463                         $fields,
1464                         array(
1465                                 'page_id' => $pageId,
1466                                 'page_latest=rev_id',
1467                                 ),
1468                         __METHOD__ );
1469
1470                 if( $current ) {
1471                         $row = array(
1472                                 'page'       => $pageId,
1473                                 'comment'    => $summary,
1474                                 'minor_edit' => $minor,
1475                                 'text_id'    => $current->rev_text_id,
1476                                 'parent_id'  => $current->page_latest,
1477                                 'len'        => $current->rev_len,
1478                                 'sha1'       => $current->rev_sha1
1479                         );
1480
1481                         if ( $wgContentHandlerUseDB ) {
1482                                 $row[ 'content_model' ] = $current->rev_content_model;
1483                                 $row[ 'content_format' ] = $current->rev_content_format;
1484                         }
1485
1486                         $revision = new Revision( $row );
1487                         $revision->setTitle( Title::makeTitle( $current->page_namespace, $current->page_title ) );
1488                 } else {
1489                         $revision = null;
1490                 }
1491
1492                 wfProfileOut( __METHOD__ );
1493                 return $revision;
1494         }
1495
1496         /**
1497          * Determine if the current user is allowed to view a particular
1498          * field of this revision, if it's marked as deleted.
1499          *
1500          * @param $field Integer:one of self::DELETED_TEXT,
1501          *                              self::DELETED_COMMENT,
1502          *                              self::DELETED_USER
1503          * @param $user User object to check, or null to use $wgUser
1504          * @return Boolean
1505          */
1506         public function userCan( $field, User $user = null ) {
1507                 return self::userCanBitfield( $this->mDeleted, $field, $user );
1508         }
1509
1510         /**
1511          * Determine if the current user is allowed to view a particular
1512          * field of this revision, if it's marked as deleted. This is used
1513          * by various classes to avoid duplication.
1514          *
1515          * @param $bitfield Integer: current field
1516          * @param $field Integer: one of self::DELETED_TEXT = File::DELETED_FILE,
1517          *                               self::DELETED_COMMENT = File::DELETED_COMMENT,
1518          *                               self::DELETED_USER = File::DELETED_USER
1519          * @param $user User object to check, or null to use $wgUser
1520          * @return Boolean
1521          */
1522         public static function userCanBitfield( $bitfield, $field, User $user = null ) {
1523                 if( $bitfield & $field ) { // aspect is deleted
1524                         if ( $bitfield & self::DELETED_RESTRICTED ) {
1525                                 $permission = 'suppressrevision';
1526                         } elseif ( $field & self::DELETED_TEXT ) {
1527                                 $permission = 'deletedtext';
1528                         } else {
1529                                 $permission = 'deletedhistory';
1530                         }
1531                         wfDebug( "Checking for $permission due to $field match on $bitfield\n" );
1532                         if ( $user === null ) {
1533                                 global $wgUser;
1534                                 $user = $wgUser;
1535                         }
1536                         return $user->isAllowed( $permission );
1537                 } else {
1538                         return true;
1539                 }
1540         }
1541
1542         /**
1543          * Get rev_timestamp from rev_id, without loading the rest of the row
1544          *
1545          * @param $title Title
1546          * @param $id Integer
1547          * @return String
1548          */
1549         static function getTimestampFromId( $title, $id ) {
1550                 $dbr = wfGetDB( DB_SLAVE );
1551                 // Casting fix for DB2
1552                 if ( $id == '' ) {
1553                         $id = 0;
1554                 }
1555                 $conds = array( 'rev_id' => $id );
1556                 $conds['rev_page'] = $title->getArticleID();
1557                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1558                 if ( $timestamp === false && wfGetLB()->getServerCount() > 1 ) {
1559                         # Not in slave, try master
1560                         $dbw = wfGetDB( DB_MASTER );
1561                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1562                 }
1563                 return wfTimestamp( TS_MW, $timestamp );
1564         }
1565
1566         /**
1567          * Get count of revisions per page...not very efficient
1568          *
1569          * @param $db DatabaseBase
1570          * @param $id Integer: page id
1571          * @return Integer
1572          */
1573         static function countByPageId( $db, $id ) {
1574                 $row = $db->selectRow( 'revision', array( 'revCount' => 'COUNT(*)' ),
1575                         array( 'rev_page' => $id ), __METHOD__ );
1576                 if( $row ) {
1577                         return $row->revCount;
1578                 }
1579                 return 0;
1580         }
1581
1582         /**
1583          * Get count of revisions per page...not very efficient
1584          *
1585          * @param $db DatabaseBase
1586          * @param $title Title
1587          * @return Integer
1588          */
1589         static function countByTitle( $db, $title ) {
1590                 $id = $title->getArticleID();
1591                 if( $id ) {
1592                         return self::countByPageId( $db, $id );
1593                 }
1594                 return 0;
1595         }
1596
1597         /**
1598          * Check if no edits were made by other users since
1599          * the time a user started editing the page. Limit to
1600          * 50 revisions for the sake of performance.
1601          *
1602          * @since 1.20
1603          *
1604          * @param DatabaseBase|int $db the Database to perform the check on. May be given as a Database object or
1605          *        a database identifier usable with wfGetDB.
1606          * @param int $pageId the ID of the page in question
1607          * @param int $userId the ID of the user in question
1608          * @param string $since look at edits since this time
1609          *
1610          * @return bool True if the given user was the only one to edit since the given timestamp
1611          */
1612         public static function userWasLastToEdit( $db, $pageId, $userId, $since ) {
1613                 if ( !$userId ) return false;
1614
1615                 if ( is_int( $db ) ) {
1616                         $db = wfGetDB( $db );
1617                 }
1618
1619                 $res = $db->select( 'revision',
1620                         'rev_user',
1621                         array(
1622                                 'rev_page' => $pageId,
1623                                 'rev_timestamp > ' . $db->addQuotes( $db->timestamp( $since ) )
1624                         ),
1625                         __METHOD__,
1626                         array( 'ORDER BY' => 'rev_timestamp ASC', 'LIMIT' => 50 ) );
1627                 foreach ( $res as $row ) {
1628                         if ( $row->rev_user != $userId ) {
1629                                 return false;
1630                         }
1631                 }
1632                 return true;
1633         }
1634 }