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