includes/Revision.php

   1 <?php
   2
   3 /**
   4  * @todo document
   5  */
   6 class Revision {
   7         const DELETED_TEXT = 1;
   8         const DELETED_COMMENT = 2;
   9         const DELETED_USER = 4;
  10         const DELETED_RESTRICTED = 8;
  11         // Convenience field
  12         const SUPPRESSED_USER = 12;
  13         // Audience options for Revision::getText()
  14         const FOR_PUBLIC = 1;
  15         const FOR_THIS_USER = 2;
  16         const RAW = 3;
  17
  18         /**
  19          * Load a page revision from a given revision ID number.
  20          * Returns null if no such revision can be found.
  21          *
  22          * @param $id Integer
  23          * @return Revision or null
  24          */
  25         public static function newFromId( $id ) {
  26                 return Revision::newFromConds(
  27                         array( 'page_id=rev_page',
  28                                    'rev_id' => intval( $id ) ) );
  29         }
  30
  31         /**
  32          * Load either the current, or a specified, revision
  33          * that's attached to a given title. If not attached
  34          * to that title, will return null.
  35          *
  36          * @param $title Title
  37          * @param $id Integer (optional)
  38          * @return Revision or null
  39          */
  40         public static function newFromTitle( $title, $id = 0 ) {
  41                 $conds = array(
  42                         'page_namespace' => $title->getNamespace(),
  43                         'page_title'     => $title->getDBkey()
  44                 );
  45                 if ( $id ) {
  46                         // Use the specified ID
  47                         $conds['rev_id'] = $id;
  48                 } elseif ( wfGetLB()->getServerCount() > 1 ) {
  49                         // Get the latest revision ID from the master
  50                         $dbw = wfGetDB( DB_MASTER );
  51                         $latest = $dbw->selectField( 'page', 'page_latest', $conds, __METHOD__ );
  52                         if ( $latest === false ) {
  53                                 return null; // page does not exist
  54                         }
  55                         $conds['rev_id'] = $latest;
  56                 } else {
  57                         // Use a join to get the latest revision
  58                         $conds[] = 'rev_id=page_latest';
  59                 }
  60                 $conds[] = 'page_id=rev_page';
  61                 return Revision::newFromConds( $conds );
  62         }
  63
  64         /**
  65          * Load either the current, or a specified, revision
  66          * that's attached to a given page ID.
  67          * Returns null if no such revision can be found.
  68          *
  69          * @param $revId Integer
  70          * @param $pageId Integer (optional)
  71          * @return Revision or null
  72          */
  73         public static function newFromPageId( $pageId, $revId = 0 ) {
  74                 $conds = array( 'page_id' => $pageId );
  75                 if ( $revId ) {
  76                         $conds['rev_id'] = $revId;
  77                 } elseif ( wfGetLB()->getServerCount() > 1 ) {
  78                         // Get the latest revision ID from the master
  79                         $dbw = wfGetDB( DB_MASTER );
  80                         $latest = $dbw->selectField( 'page', 'page_latest', $conds, __METHOD__ );
  81                         if ( $latest === false ) {
  82                                 return null; // page does not exist
  83                         }
  84                         $conds['rev_id'] = $latest;
  85                 } else {
  86                         $conds[] = 'rev_id = page_latest';
  87                 }
  88                 $conds[] = 'page_id=rev_page';
  89                 return Revision::newFromConds( $conds );
  90         }
  91
  92         /**
  93          * Make a fake revision object from an archive table row. This is queried
  94          * for permissions or even inserted (as in Special:Undelete)
  95          * @todo FIXME: Should be a subclass for RevisionDelete. [TS]
  96          *
  97          * @param $row
  98          * @param $overrides array
  99          *
 100          * @return Revision
 101          */
 102         public static function newFromArchiveRow( $row, $overrides = array() ) {
 103                 $attribs = $overrides + array(
 104                         'page'       => isset( $row->ar_page_id ) ? $row->ar_page_id : null,
 105                         'id'         => isset( $row->ar_rev_id ) ? $row->ar_rev_id : null,
 106                         'comment'    => $row->ar_comment,
 107                         'user'       => $row->ar_user,
 108                         'user_text'  => $row->ar_user_text,
 109                         'timestamp'  => $row->ar_timestamp,
 110                         'minor_edit' => $row->ar_minor_edit,
 111                         'text_id'    => isset( $row->ar_text_id ) ? $row->ar_text_id : null,
 112                         'deleted'    => $row->ar_deleted,
 113                         'len'        => $row->ar_len);
 114                 if ( isset( $row->ar_text ) && !$row->ar_text_id ) {
 115                         // Pre-1.5 ar_text row
 116                         $attribs['text'] = self::getRevisionText( $row, 'ar_' );
 117                         if ( $attribs['text'] === false ) {
 118                                 throw new MWException( 'Unable to load text from archive row (possibly bug 22624)' );
 119                         }
 120                 }
 121                 return new self( $attribs );
 122         }
 123
 124         /**
 125          * @param $row
 126          * @return Revision
 127          */
 128         public static function newFromRow( $row ) {
 129                 return new self( $row );
 130         }
 131
 132         /**
 133          * Load a page revision from a given revision ID number.
 134          * Returns null if no such revision can be found.
 135          *
 136          * @param $db DatabaseBase
 137          * @param $id Integer
 138          * @return Revision or null
 139          */
 140         public static function loadFromId( $db, $id ) {
 141                 return Revision::loadFromConds( $db,
 142                         array( 'page_id=rev_page',
 143                                    'rev_id' => intval( $id ) ) );
 144         }
 145
 146         /**
 147          * Load either the current, or a specified, revision
 148          * that's attached to a given page. If not attached
 149          * to that page, will return null.
 150          *
 151          * @param $db DatabaseBase
 152          * @param $pageid Integer
 153          * @param $id Integer
 154          * @return Revision or null
 155          */
 156         public static function loadFromPageId( $db, $pageid, $id = 0 ) {
 157                 $conds = array( 'page_id=rev_page','rev_page' => intval( $pageid ), 'page_id'=>intval( $pageid ) );
 158                 if( $id ) {
 159                         $conds['rev_id'] = intval( $id );
 160                 } else {
 161                         $conds[] = 'rev_id=page_latest';
 162                 }
 163                 return Revision::loadFromConds( $db, $conds );
 164         }
 165
 166         /**
 167          * Load either the current, or a specified, revision
 168          * that's attached to a given page. If not attached
 169          * to that page, will return null.
 170          *
 171          * @param $db DatabaseBase
 172          * @param $title Title
 173          * @param $id Integer
 174          * @return Revision or null
 175          */
 176         public static function loadFromTitle( $db, $title, $id = 0 ) {
 177                 if( $id ) {
 178                         $matchId = intval( $id );
 179                 } else {
 180                         $matchId = 'page_latest';
 181                 }
 182                 return Revision::loadFromConds(
 183                         $db,
 184                         array( "rev_id=$matchId",
 185                                    'page_id=rev_page',
 186                                    'page_namespace' => $title->getNamespace(),
 187                                    'page_title'     => $title->getDBkey() ) );
 188         }
 189
 190         /**
 191          * Load the revision for the given title with the given timestamp.
 192          * WARNING: Timestamps may in some circumstances not be unique,
 193          * so this isn't the best key to use.
 194          *
 195          * @param $db DatabaseBase
 196          * @param $title Title
 197          * @param $timestamp String
 198          * @return Revision or null
 199          */
 200         public static function loadFromTimestamp( $db, $title, $timestamp ) {
 201                 return Revision::loadFromConds(
 202                         $db,
 203                         array( 'rev_timestamp'  => $db->timestamp( $timestamp ),
 204                                    'page_id=rev_page',
 205                                    'page_namespace' => $title->getNamespace(),
 206                                    'page_title'     => $title->getDBkey() ) );
 207         }
 208
 209         /**
 210          * Given a set of conditions, fetch a revision.
 211          *
 212          * @param $conditions Array
 213          * @return Revision or null
 214          */
 215         public static function newFromConds( $conditions ) {
 216                 $db = wfGetDB( DB_SLAVE );
 217                 $row = Revision::loadFromConds( $db, $conditions );
 218                 if( is_null( $row ) && wfGetLB()->getServerCount() > 1 ) {
 219                         $dbw = wfGetDB( DB_MASTER );
 220                         $row = Revision::loadFromConds( $dbw, $conditions );
 221                 }
 222                 return $row;
 223         }
 224
 225         /**
 226          * Given a set of conditions, fetch a revision from
 227          * the given database connection.
 228          *
 229          * @param $db DatabaseBase
 230          * @param $conditions Array
 231          * @return Revision or null
 232          */
 233         private static function loadFromConds( $db, $conditions ) {
 234                 $res = Revision::fetchFromConds( $db, $conditions );
 235                 if( $res ) {
 236                         $row = $res->fetchObject();
 237                         $res->free();
 238                         if( $row ) {
 239                                 $ret = new Revision( $row );
 240                                 return $ret;
 241                         }
 242                 }
 243                 $ret = null;
 244                 return $ret;
 245         }
 246
 247         /**
 248          * Return a wrapper for a series of database rows to
 249          * fetch all of a given page's revisions in turn.
 250          * Each row can be fed to the constructor to get objects.
 251          *
 252          * @param $title Title
 253          * @return ResultWrapper
 254          */
 255         public static function fetchRevision( $title ) {
 256                 return Revision::fetchFromConds(
 257                         wfGetDB( DB_SLAVE ),
 258                         array( 'rev_id=page_latest',
 259                                    'page_namespace' => $title->getNamespace(),
 260                                    'page_title'     => $title->getDBkey(),
 261                                    'page_id=rev_page' ) );
 262         }
 263
 264         /**
 265          * Given a set of conditions, return a ResultWrapper
 266          * which will return matching database rows with the
 267          * fields necessary to build Revision objects.
 268          *
 269          * @param $db DatabaseBase
 270          * @param $conditions Array
 271          * @return ResultWrapper
 272          */
 273         private static function fetchFromConds( $db, $conditions ) {
 274                 $fields = self::selectFields();
 275                 $fields[] = 'page_namespace';
 276                 $fields[] = 'page_title';
 277                 $fields[] = 'page_latest';
 278                 return $db->select(
 279                         array( 'page', 'revision' ),
 280                         $fields,
 281                         $conditions,
 282                         __METHOD__,
 283                         array( 'LIMIT' => 1 ) );
 284         }
 285
 286         /**
 287          * Return the list of revision fields that should be selected to create
 288          * a new revision.
 289          */
 290         public static function selectFields() {
 291                 return array(
 292                         'rev_id',
 293                         'rev_page',
 294                         'rev_text_id',
 295                         'rev_timestamp',
 296                         'rev_comment',
 297                         'rev_user_text,'.
 298                         'rev_user',
 299                         'rev_minor_edit',
 300                         'rev_deleted',
 301                         'rev_len',
 302                         'rev_parent_id'
 303                 );
 304         }
 305
 306         /**
 307          * Return the list of text fields that should be selected to read the
 308          * revision text
 309          */
 310         static function selectTextFields() {
 311                 return array(
 312                         'old_text',
 313                         'old_flags'
 314                 );
 315         }
 316
 317         /**
 318          * Return the list of page fields that should be selected from page table
 319          */
 320         static function selectPageFields() {
 321                 return array(
 322                         'page_namespace',
 323                         'page_title',
 324                         'page_latest'
 325                 );
 326         }
 327
 328         /**
 329          * Constructor
 330          *
 331          * @param $row Mixed: either a database row or an array
 332          * @access private
 333          */
 334         function __construct( $row ) {
 335                 if( is_object( $row ) ) {
 336                         $this->mId        = intval( $row->rev_id );
 337                         $this->mPage      = intval( $row->rev_page );
 338                         $this->mTextId    = intval( $row->rev_text_id );
 339                         $this->mComment   =         $row->rev_comment;
 340                         $this->mUserText  =         $row->rev_user_text;
 341                         $this->mUser      = intval( $row->rev_user );
 342                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 343                         $this->mTimestamp =         $row->rev_timestamp;
 344                         $this->mDeleted   = intval( $row->rev_deleted );
 345
 346                         if( !isset( $row->rev_parent_id ) ) {
 347                                 $this->mParentId = is_null($row->rev_parent_id) ? null : 0;
 348                         } else {
 349                                 $this->mParentId  = intval( $row->rev_parent_id );
 350                         }
 351
 352                         if( !isset( $row->rev_len ) || is_null( $row->rev_len ) ) {
 353                                 $this->mSize = null;
 354                         } else {
 355                                 $this->mSize = intval( $row->rev_len );
 356                         }
 357
 358                         if( isset( $row->page_latest ) ) {
 359                                 $this->mCurrent = ( $row->rev_id == $row->page_latest );
 360                                 $this->mTitle = Title::newFromRow( $row );
 361                         } else {
 362                                 $this->mCurrent = false;
 363                                 $this->mTitle = null;
 364                         }
 365
 366                         // Lazy extraction...
 367                         $this->mText      = null;
 368                         if( isset( $row->old_text ) ) {
 369                                 $this->mTextRow = $row;
 370                         } else {
 371                                 // 'text' table row entry will be lazy-loaded
 372                                 $this->mTextRow = null;
 373                         }
 374                 } elseif( is_array( $row ) ) {
 375                         // Build a new revision to be saved...
 376                         global $wgUser;
 377
 378                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 379                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 380                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 381                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 382                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 383                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 384                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestamp( TS_MW );
 385                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 386                         $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
 387                         $this->mParentId  = isset( $row['parent_id']  ) ? intval( $row['parent_id']  ) : null;
 388
 389                         // Enforce spacing trimming on supplied text
 390                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 391                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 392                         $this->mTextRow   = null;
 393
 394                         $this->mTitle     = null; # Load on demand if needed
 395                         $this->mCurrent   = false;
 396                         # If we still have no len_size, see it we have the text to figure it out
 397                         if ( !$this->mSize )
 398                                 $this->mSize      = is_null( $this->mText ) ? null : strlen( $this->mText );
 399                 } else {
 400                         throw new MWException( 'Revision constructor passed invalid row format.' );
 401                 }
 402                 $this->mUnpatrolled = null;
 403         }
 404
 405         /**
 406          * Get revision ID
 407          *
 408          * @return Integer
 409          */
 410         public function getId() {
 411                 return $this->mId;
 412         }
 413
 414         /**
 415          * Get text row ID
 416          *
 417          * @return Integer
 418          */
 419         public function getTextId() {
 420                 return $this->mTextId;
 421         }
 422
 423         /**
 424          * Get parent revision ID (the original previous page revision)
 425          *
 426          * @return Integer
 427          */
 428         public function getParentId() {
 429                 return $this->mParentId;
 430         }
 431
 432         /**
 433          * Returns the length of the text in this revision, or null if unknown.
 434          *
 435          * @return Integer
 436          */
 437         public function getSize() {
 438                 return $this->mSize;
 439         }
 440
 441         /**
 442          * Returns the title of the page associated with this entry.
 443          *
 444          * @return Title
 445          */
 446         public function getTitle() {
 447                 if( isset( $this->mTitle ) ) {
 448                         return $this->mTitle;
 449                 }
 450                 $dbr = wfGetDB( DB_SLAVE );
 451                 $row = $dbr->selectRow(
 452                         array( 'page', 'revision' ),
 453                         array( 'page_namespace', 'page_title' ),
 454                         array( 'page_id=rev_page',
 455                                    'rev_id' => $this->mId ),
 456                         'Revision::getTitle' );
 457                 if( $row ) {
 458                         $this->mTitle = Title::makeTitle( $row->page_namespace, $row->page_title );
 459                 }
 460                 return $this->mTitle;
 461         }
 462
 463         /**
 464          * Set the title of the revision
 465          *
 466          * @param $title Title
 467          */
 468         public function setTitle( $title ) {
 469                 $this->mTitle = $title;
 470         }
 471
 472         /**
 473          * Get the page ID
 474          *
 475          * @return Integer
 476          */
 477         public function getPage() {
 478                 return $this->mPage;
 479         }
 480
 481         /**
 482          * Fetch revision's user id if it's available to the specified audience.
 483          * If the specified audience does not have access to it, zero will be
 484          * returned.
 485          *
 486          * @param $audience Integer: one of:
 487          *      Revision::FOR_PUBLIC       to be displayed to all users
 488          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 489          *      Revision::RAW              get the ID regardless of permissions
 490          *
 491          *
 492          * @return Integer
 493          */
 494         public function getUser( $audience = self::FOR_PUBLIC ) {
 495                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 496                         return 0;
 497                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER ) ) {
 498                         return 0;
 499                 } else {
 500                         return $this->mUser;
 501                 }
 502         }
 503
 504         /**
 505          * Fetch revision's user id without regard for the current user's permissions
 506          *
 507          * @return String
 508          */
 509         public function getRawUser() {
 510                 return $this->mUser;
 511         }
 512
 513         /**
 514          * Fetch revision's username if it's available to the specified audience.
 515          * If the specified audience does not have access to the username, an
 516          * empty string will be returned.
 517          *
 518          * @param $audience Integer: one of:
 519          *      Revision::FOR_PUBLIC       to be displayed to all users
 520          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 521          *      Revision::RAW              get the text regardless of permissions
 522          *
 523          * @return string
 524          */
 525         public function getUserText( $audience = self::FOR_PUBLIC ) {
 526                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 527                         return '';
 528                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER ) ) {
 529                         return '';
 530                 } else {
 531                         return $this->mUserText;
 532                 }
 533         }
 534
 535         /**
 536          * Fetch revision's username without regard for view restrictions
 537          *
 538          * @return String
 539          */
 540         public function getRawUserText() {
 541                 return $this->mUserText;
 542         }
 543
 544         /**
 545          * Fetch revision comment if it's available to the specified audience.
 546          * If the specified audience does not have access to the comment, an
 547          * empty string will be returned.
 548          *
 549          * @param $audience Integer: one of:
 550          *      Revision::FOR_PUBLIC       to be displayed to all users
 551          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 552          *      Revision::RAW              get the text regardless of permissions
 553          *
 554          * @return String
 555          */
 556         function getComment( $audience = self::FOR_PUBLIC ) {
 557                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_COMMENT ) ) {
 558                         return '';
 559                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_COMMENT ) ) {
 560                         return '';
 561                 } else {
 562                         return $this->mComment;
 563                 }
 564         }
 565
 566         /**
 567          * Fetch revision comment without regard for the current user's permissions
 568          *
 569          * @return String
 570          */
 571         public function getRawComment() {
 572                 return $this->mComment;
 573         }
 574
 575         /**
 576          * @return Boolean
 577          */
 578         public function isMinor() {
 579                 return (bool)$this->mMinorEdit;
 580         }
 581
 582         /**
 583          * @return Integer rcid of the unpatrolled row, zero if there isn't one
 584          */
 585         public function isUnpatrolled() {
 586                 if( $this->mUnpatrolled !== null ) {
 587                         return $this->mUnpatrolled;
 588                 }
 589                 $dbr = wfGetDB( DB_SLAVE );
 590                 $this->mUnpatrolled = $dbr->selectField( 'recentchanges',
 591                         'rc_id',
 592                         array( // Add redundant user,timestamp condition so we can use the existing index
 593                                 'rc_user_text'  => $this->getRawUserText(),
 594                                 'rc_timestamp'  => $dbr->timestamp( $this->getTimestamp() ),
 595                                 'rc_this_oldid' => $this->getId(),
 596                                 'rc_patrolled'  => 0
 597                         ),
 598                         __METHOD__
 599                 );
 600                 return (int)$this->mUnpatrolled;
 601         }
 602
 603         /**
 604          * @param $field int one of DELETED_* bitfield constants
 605          *
 606          * @return Boolean
 607          */
 608         public function isDeleted( $field ) {
 609                 return ( $this->mDeleted & $field ) == $field;
 610         }
 611
 612         /**
 613          * Get the deletion bitfield of the revision
 614          *
 615          * @return int
 616          */
 617         public function getVisibility() {
 618                 return (int)$this->mDeleted;
 619         }
 620
 621         /**
 622          * Fetch revision text if it's available to the specified audience.
 623          * If the specified audience does not have the ability to view this
 624          * revision, an empty string will be returned.
 625          *
 626          * @param $audience Integer: one of:
 627          *      Revision::FOR_PUBLIC       to be displayed to all users
 628          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 629          *      Revision::RAW              get the text regardless of permissions
 630          *
 631          * @return String
 632          */
 633         public function getText( $audience = self::FOR_PUBLIC ) {
 634                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_TEXT ) ) {
 635                         return '';
 636                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_TEXT ) ) {
 637                         return '';
 638                 } else {
 639                         return $this->getRawText();
 640                 }
 641         }
 642
 643         /**
 644          * Alias for getText(Revision::FOR_THIS_USER)
 645          *
 646          * @deprecated since 1.17
 647          * @return String
 648          */
 649         public function revText() {
 650                 wfDeprecated( __METHOD__ );
 651                 return $this->getText( self::FOR_THIS_USER );
 652         }
 653
 654         /**
 655          * Fetch revision text without regard for view restrictions
 656          *
 657          * @return String
 658          */
 659         public function getRawText() {
 660                 if( is_null( $this->mText ) ) {
 661                         // Revision text is immutable. Load on demand:
 662                         $this->mText = $this->loadText();
 663                 }
 664                 return $this->mText;
 665         }
 666
 667         /**
 668          * @return String
 669          */
 670         public function getTimestamp() {
 671                 return wfTimestamp( TS_MW, $this->mTimestamp );
 672         }
 673
 674         /**
 675          * @return Boolean
 676          */
 677         public function isCurrent() {
 678                 return $this->mCurrent;
 679         }
 680
 681         /**
 682          * Get previous revision for this title
 683          *
 684          * @return Revision or null
 685          */
 686         public function getPrevious() {
 687                 if( $this->getTitle() ) {
 688                         $prev = $this->getTitle()->getPreviousRevisionID( $this->getId() );
 689                         if( $prev ) {
 690                                 return Revision::newFromTitle( $this->getTitle(), $prev );
 691                         }
 692                 }
 693                 return null;
 694         }
 695
 696         /**
 697          * Get next revision for this title
 698          *
 699          * @return Revision or null
 700          */
 701         public function getNext() {
 702                 if( $this->getTitle() ) {
 703                         $next = $this->getTitle()->getNextRevisionID( $this->getId() );
 704                         if ( $next ) {
 705                                 return Revision::newFromTitle( $this->getTitle(), $next );
 706                         }
 707                 }
 708                 return null;
 709         }
 710
 711         /**
 712          * Get previous revision Id for this page_id
 713          * This is used to populate rev_parent_id on save
 714          *
 715          * @param $db DatabaseBase
 716          * @return Integer
 717          */
 718         private function getPreviousRevisionId( $db ) {
 719                 if( is_null( $this->mPage ) ) {
 720                         return 0;
 721                 }
 722                 # Use page_latest if ID is not given
 723                 if( !$this->mId ) {
 724                         $prevId = $db->selectField( 'page', 'page_latest',
 725                                 array( 'page_id' => $this->mPage ),
 726                                 __METHOD__ );
 727                 } else {
 728                         $prevId = $db->selectField( 'revision', 'rev_id',
 729                                 array( 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ),
 730                                 __METHOD__,
 731                                 array( 'ORDER BY' => 'rev_id DESC' ) );
 732                 }
 733                 return intval( $prevId );
 734         }
 735
 736         /**
 737           * Get revision text associated with an old or archive row
 738           * $row is usually an object from wfFetchRow(), both the flags and the text
 739           * field must be included
 740           *
 741           * @param $row Object: the text data
 742           * @param $prefix String: table prefix (default 'old_')
 743           * @return String: text the text requested or false on failure
 744           */
 745         public static function getRevisionText( $row, $prefix = 'old_' ) {
 746                 wfProfileIn( __METHOD__ );
 747
 748                 # Get data
 749                 $textField = $prefix . 'text';
 750                 $flagsField = $prefix . 'flags';
 751
 752                 if( isset( $row->$flagsField ) ) {
 753                         $flags = explode( ',', $row->$flagsField );
 754                 } else {
 755                         $flags = array();
 756                 }
 757
 758                 if( isset( $row->$textField ) ) {
 759                         $text = $row->$textField;
 760                 } else {
 761                         wfProfileOut( __METHOD__ );
 762                         return false;
 763                 }
 764
 765                 # Use external methods for external objects, text in table is URL-only then
 766                 if ( in_array( 'external', $flags ) ) {
 767                         $url = $text;
 768                         $parts = explode( '://', $url, 2 );
 769                         if( count( $parts ) == 1 || $parts[1] == '' ) {
 770                                 wfProfileOut( __METHOD__ );
 771                                 return false;
 772                         }
 773                         $text = ExternalStore::fetchFromURL( $url );
 774                 }
 775
 776                 // If the text was fetched without an error, convert it
 777                 if ( $text !== false ) {
 778                         if( in_array( 'gzip', $flags ) ) {
 779                                 # Deal with optional compression of archived pages.
 780                                 # This can be done periodically via maintenance/compressOld.php, and
 781                                 # as pages are saved if $wgCompressRevisions is set.
 782                                 $text = gzinflate( $text );
 783                         }
 784
 785                         if( in_array( 'object', $flags ) ) {
 786                                 # Generic compressed storage
 787                                 $obj = unserialize( $text );
 788                                 if ( !is_object( $obj ) ) {
 789                                         // Invalid object
 790                                         wfProfileOut( __METHOD__ );
 791                                         return false;
 792                                 }
 793                                 $text = $obj->getText();
 794                         }
 795
 796                         global $wgLegacyEncoding;
 797                         if( $text !== false && $wgLegacyEncoding
 798                                 && !in_array( 'utf-8', $flags ) && !in_array( 'utf8', $flags ) )
 799                         {
 800                                 # Old revisions kept around in a legacy encoding?
 801                                 # Upconvert on demand.
 802                                 # ("utf8" checked for compatibility with some broken
 803                                 #  conversion scripts 2008-12-30)
 804                                 global $wgContLang;
 805                                 $text = $wgContLang->iconv( $wgLegacyEncoding, 'UTF-8', $text );
 806                         }
 807                 }
 808                 wfProfileOut( __METHOD__ );
 809                 return $text;
 810         }
 811
 812         /**
 813          * If $wgCompressRevisions is enabled, we will compress data.
 814          * The input string is modified in place.
 815          * Return value is the flags field: contains 'gzip' if the
 816          * data is compressed, and 'utf-8' if we're saving in UTF-8
 817          * mode.
 818          *
 819          * @param $text Mixed: reference to a text
 820          * @return String
 821          */
 822         public static function compressRevisionText( &$text ) {
 823                 global $wgCompressRevisions;
 824                 $flags = array();
 825
 826                 # Revisions not marked this way will be converted
 827                 # on load if $wgLegacyCharset is set in the future.
 828                 $flags[] = 'utf-8';
 829
 830                 if( $wgCompressRevisions ) {
 831                         if( function_exists( 'gzdeflate' ) ) {
 832                                 $text = gzdeflate( $text );
 833                                 $flags[] = 'gzip';
 834                         } else {
 835                                 wfDebug( "Revision::compressRevisionText() -- no zlib support, not compressing\n" );
 836                         }
 837                 }
 838                 return implode( ',', $flags );
 839         }
 840
 841         /**
 842          * Insert a new revision into the database, returning the new revision ID
 843          * number on success and dies horribly on failure.
 844          *
 845          * @param $dbw DatabaseBase: (master connection)
 846          * @return Integer
 847          */
 848         public function insertOn( $dbw ) {
 849                 global $wgDefaultExternalStore;
 850
 851                 wfProfileIn( __METHOD__ );
 852
 853                 $data = $this->mText;
 854                 $flags = Revision::compressRevisionText( $data );
 855
 856                 # Write to external storage if required
 857                 if( $wgDefaultExternalStore ) {
 858                         // Store and get the URL
 859                         $data = ExternalStore::insertToDefault( $data );
 860                         if( !$data ) {
 861                                 throw new MWException( "Unable to store text to external storage" );
 862                         }
 863                         if( $flags ) {
 864                                 $flags .= ',';
 865                         }
 866                         $flags .= 'external';
 867                 }
 868
 869                 # Record the text (or external storage URL) to the text table
 870                 if( !isset( $this->mTextId ) ) {
 871                         $old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );
 872                         $dbw->insert( 'text',
 873                                 array(
 874                                         'old_id'    => $old_id,
 875                                         'old_text'  => $data,
 876                                         'old_flags' => $flags,
 877                                 ), __METHOD__
 878                         );
 879                         $this->mTextId = $dbw->insertId();
 880                 }
 881
 882                 if ( $this->mComment === null ) $this->mComment = "";
 883
 884                 # Record the edit in revisions
 885                 $rev_id = isset( $this->mId )
 886                         ? $this->mId
 887                         : $dbw->nextSequenceValue( 'revision_rev_id_seq' );
 888                 $dbw->insert( 'revision',
 889                         array(
 890                                 'rev_id'         => $rev_id,
 891                                 'rev_page'       => $this->mPage,
 892                                 'rev_text_id'    => $this->mTextId,
 893                                 'rev_comment'    => $this->mComment,
 894                                 'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
 895                                 'rev_user'       => $this->mUser,
 896                                 'rev_user_text'  => $this->mUserText,
 897                                 'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
 898                                 'rev_deleted'    => $this->mDeleted,
 899                                 'rev_len'        => $this->mSize,
 900                                 'rev_parent_id'  => is_null($this->mParentId) ?
 901                                         $this->getPreviousRevisionId( $dbw ) : $this->mParentId
 902                         ), __METHOD__
 903                 );
 904
 905                 $this->mId = !is_null( $rev_id ) ? $rev_id : $dbw->insertId();
 906
 907                 wfRunHooks( 'RevisionInsertComplete', array( &$this, $data, $flags ) );
 908
 909                 wfProfileOut( __METHOD__ );
 910                 return $this->mId;
 911         }
 912
 913         /**
 914          * Lazy-load the revision's text.
 915          * Currently hardcoded to the 'text' table storage engine.
 916          *
 917          * @return String
 918          */
 919         protected function loadText() {
 920                 wfProfileIn( __METHOD__ );
 921
 922                 // Caching may be beneficial for massive use of external storage
 923                 global $wgRevisionCacheExpiry, $wgMemc;
 924                 $textId = $this->getTextId();
 925                 $key = wfMemcKey( 'revisiontext', 'textid', $textId );
 926                 if( $wgRevisionCacheExpiry ) {
 927                         $text = $wgMemc->get( $key );
 928                         if( is_string( $text ) ) {
 929                                 wfDebug( __METHOD__ . ": got id $textId from cache\n" );
 930                                 wfProfileOut( __METHOD__ );
 931                                 return $text;
 932                         }
 933                 }
 934
 935                 // If we kept data for lazy extraction, use it now...
 936                 if ( isset( $this->mTextRow ) ) {
 937                         $row = $this->mTextRow;
 938                         $this->mTextRow = null;
 939                 } else {
 940                         $row = null;
 941                 }
 942
 943                 if( !$row ) {
 944                         // Text data is immutable; check slaves first.
 945                         $dbr = wfGetDB( DB_SLAVE );
 946                         $row = $dbr->selectRow( 'text',
 947                                 array( 'old_text', 'old_flags' ),
 948                                 array( 'old_id' => $this->getTextId() ),
 949                                 __METHOD__ );
 950                 }
 951
 952                 if( !$row && wfGetLB()->getServerCount() > 1 ) {
 953                         // Possible slave lag!
 954                         $dbw = wfGetDB( DB_MASTER );
 955                         $row = $dbw->selectRow( 'text',
 956                                 array( 'old_text', 'old_flags' ),
 957                                 array( 'old_id' => $this->getTextId() ),
 958                                 __METHOD__ );
 959                 }
 960
 961                 $text = self::getRevisionText( $row );
 962
 963                 # No negative caching -- negative hits on text rows may be due to corrupted slave servers
 964                 if( $wgRevisionCacheExpiry && $text !== false ) {
 965                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
 966                 }
 967
 968                 wfProfileOut( __METHOD__ );
 969
 970                 return $text;
 971         }
 972
 973         /**
 974          * Create a new null-revision for insertion into a page's
 975          * history. This will not re-save the text, but simply refer
 976          * to the text from the previous version.
 977          *
 978          * Such revisions can for instance identify page rename
 979          * operations and other such meta-modifications.
 980          *
 981          * @param $dbw DatabaseBase
 982          * @param $pageId Integer: ID number of the page to read from
 983          * @param $summary String: revision's summary
 984          * @param $minor Boolean: whether the revision should be considered as minor
 985          * @return Revision|null on error
 986          */
 987         public static function newNullRevision( $dbw, $pageId, $summary, $minor ) {
 988                 wfProfileIn( __METHOD__ );
 989
 990                 $current = $dbw->selectRow(
 991                         array( 'page', 'revision' ),
 992                         array( 'page_latest', 'rev_text_id', 'rev_len' ),
 993                         array(
 994                                 'page_id' => $pageId,
 995                                 'page_latest=rev_id',
 996                                 ),
 997                         __METHOD__ );
 998
 999                 if( $current ) {
1000                         $revision = new Revision( array(
1001                                 'page'       => $pageId,
1002                                 'comment'    => $summary,
1003                                 'minor_edit' => $minor,
1004                                 'text_id'    => $current->rev_text_id,
1005                                 'parent_id'  => $current->page_latest,
1006                                 'len'        => $current->rev_len
1007                                 ) );
1008                 } else {
1009                         $revision = null;
1010                 }
1011
1012                 wfProfileOut( __METHOD__ );
1013                 return $revision;
1014         }
1015
1016         /**
1017          * Determine if the current user is allowed to view a particular
1018          * field of this revision, if it's marked as deleted.
1019          *
1020          * @param $field Integer:one of self::DELETED_TEXT,
1021          *                              self::DELETED_COMMENT,
1022          *                              self::DELETED_USER
1023          * @return Boolean
1024          */
1025         public function userCan( $field ) {
1026                 return self::userCanBitfield( $this->mDeleted, $field );
1027         }
1028
1029         /**
1030          * Determine if the current user is allowed to view a particular
1031          * field of this revision, if it's marked as deleted. This is used
1032          * by various classes to avoid duplication.
1033          *
1034          * @param $bitfield Integer: current field
1035          * @param $field Integer: one of self::DELETED_TEXT = File::DELETED_FILE,
1036          *                               self::DELETED_COMMENT = File::DELETED_COMMENT,
1037          *                               self::DELETED_USER = File::DELETED_USER
1038          * @return Boolean
1039          */
1040         public static function userCanBitfield( $bitfield, $field ) {
1041                 if( $bitfield & $field ) { // aspect is deleted
1042                         global $wgUser;
1043                         if ( $bitfield & self::DELETED_RESTRICTED ) {
1044                                 $permission = 'suppressrevision';
1045                         } elseif ( $field & self::DELETED_TEXT ) {
1046                                 $permission = 'deletedtext';
1047                         } else {
1048                                 $permission = 'deletedhistory';
1049                         }
1050                         wfDebug( "Checking for $permission due to $field match on $bitfield\n" );
1051                         return $wgUser->isAllowed( $permission );
1052                 } else {
1053                         return true;
1054                 }
1055         }
1056
1057         /**
1058          * Get rev_timestamp from rev_id, without loading the rest of the row
1059          *
1060          * @param $title Title
1061          * @param $id Integer
1062          * @return String
1063          */
1064         static function getTimestampFromId( $title, $id ) {
1065                 $dbr = wfGetDB( DB_SLAVE );
1066                 // Casting fix for DB2
1067                 if ( $id == '' ) {
1068                         $id = 0;
1069                 }
1070                 $conds = array( 'rev_id' => $id );
1071                 $conds['rev_page'] = $title->getArticleId();
1072                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1073                 if ( $timestamp === false && wfGetLB()->getServerCount() > 1 ) {
1074                         # Not in slave, try master
1075                         $dbw = wfGetDB( DB_MASTER );
1076                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1077                 }
1078                 return wfTimestamp( TS_MW, $timestamp );
1079         }
1080
1081         /**
1082          * Get count of revisions per page...not very efficient
1083          *
1084          * @param $db DatabaseBase
1085          * @param $id Integer: page id
1086          * @return Integer
1087          */
1088         static function countByPageId( $db, $id ) {
1089                 $row = $db->selectRow( 'revision', 'COUNT(*) AS revCount',
1090                         array( 'rev_page' => $id ), __METHOD__ );
1091                 if( $row ) {
1092                         return $row->revCount;
1093                 }
1094                 return 0;
1095         }
1096
1097         /**
1098          * Get count of revisions per page...not very efficient
1099          *
1100          * @param $db DatabaseBase
1101          * @param $title Title
1102          * @return Integer
1103          */
1104         static function countByTitle( $db, $title ) {
1105                 $id = $title->getArticleId();
1106                 if( $id ) {
1107                         return Revision::countByPageId( $db, $id );
1108                 }
1109                 return 0;
1110         }
1111 }