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->page_id ) ? $row->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          * Load a page revision from a given revision ID number.
 126          * Returns null if no such revision can be found.
 127          *
 128          * @param $db DatabaseBase
 129          * @param $id Integer
 130          * @return Revision or null
 131          */
 132         public static function loadFromId( $db, $id ) {
 133                 return Revision::loadFromConds( $db,
 134                         array( 'page_id=rev_page',
 135                                    'rev_id' => intval( $id ) ) );
 136         }
 137
 138         /**
 139          * Load either the current, or a specified, revision
 140          * that's attached to a given page. If not attached
 141          * to that page, will return null.
 142          *
 143          * @param $db DatabaseBase
 144          * @param $pageid Integer
 145          * @param $id Integer
 146          * @return Revision or null
 147          */
 148         public static function loadFromPageId( $db, $pageid, $id = 0 ) {
 149                 $conds = array( 'page_id=rev_page','rev_page' => intval( $pageid ), 'page_id'=>intval( $pageid ) );
 150                 if( $id ) {
 151                         $conds['rev_id'] = intval( $id );
 152                 } else {
 153                         $conds[] = 'rev_id=page_latest';
 154                 }
 155                 return Revision::loadFromConds( $db, $conds );
 156         }
 157
 158         /**
 159          * Load either the current, or a specified, revision
 160          * that's attached to a given page. If not attached
 161          * to that page, will return null.
 162          *
 163          * @param $db DatabaseBase
 164          * @param $title Title
 165          * @param $id Integer
 166          * @return Revision or null
 167          */
 168         public static function loadFromTitle( $db, $title, $id = 0 ) {
 169                 if( $id ) {
 170                         $matchId = intval( $id );
 171                 } else {
 172                         $matchId = 'page_latest';
 173                 }
 174                 return Revision::loadFromConds(
 175                         $db,
 176                         array( "rev_id=$matchId",
 177                                    'page_id=rev_page',
 178                                    'page_namespace' => $title->getNamespace(),
 179                                    'page_title'     => $title->getDBkey() ) );
 180         }
 181
 182         /**
 183          * Load the revision for the given title with the given timestamp.
 184          * WARNING: Timestamps may in some circumstances not be unique,
 185          * so this isn't the best key to use.
 186          *
 187          * @param $db DatabaseBase
 188          * @param $title Title
 189          * @param $timestamp String
 190          * @return Revision or null
 191          */
 192         public static function loadFromTimestamp( $db, $title, $timestamp ) {
 193                 return Revision::loadFromConds(
 194                         $db,
 195                         array( 'rev_timestamp'  => $db->timestamp( $timestamp ),
 196                                    'page_id=rev_page',
 197                                    'page_namespace' => $title->getNamespace(),
 198                                    'page_title'     => $title->getDBkey() ) );
 199         }
 200
 201         /**
 202          * Given a set of conditions, fetch a revision.
 203          *
 204          * @param $conditions Array
 205          * @return Revision or null
 206          */
 207         public static function newFromConds( $conditions ) {
 208                 $db = wfGetDB( DB_SLAVE );
 209                 $row = Revision::loadFromConds( $db, $conditions );
 210                 if( is_null( $row ) && wfGetLB()->getServerCount() > 1 ) {
 211                         $dbw = wfGetDB( DB_MASTER );
 212                         $row = Revision::loadFromConds( $dbw, $conditions );
 213                 }
 214                 return $row;
 215         }
 216
 217         /**
 218          * Given a set of conditions, fetch a revision from
 219          * the given database connection.
 220          *
 221          * @param $db DatabaseBase
 222          * @param $conditions Array
 223          * @return Revision or null
 224          */
 225         private static function loadFromConds( $db, $conditions ) {
 226                 $res = Revision::fetchFromConds( $db, $conditions );
 227                 if( $res ) {
 228                         $row = $res->fetchObject();
 229                         $res->free();
 230                         if( $row ) {
 231                                 $ret = new Revision( $row );
 232                                 return $ret;
 233                         }
 234                 }
 235                 $ret = null;
 236                 return $ret;
 237         }
 238
 239         /**
 240          * Return a wrapper for a series of database rows to
 241          * fetch all of a given page's revisions in turn.
 242          * Each row can be fed to the constructor to get objects.
 243          *
 244          * @param $title Title
 245          * @return ResultWrapper
 246          */
 247         public static function fetchRevision( $title ) {
 248                 return Revision::fetchFromConds(
 249                         wfGetDB( DB_SLAVE ),
 250                         array( 'rev_id=page_latest',
 251                                    'page_namespace' => $title->getNamespace(),
 252                                    'page_title'     => $title->getDBkey(),
 253                                    'page_id=rev_page' ) );
 254         }
 255
 256         /**
 257          * Given a set of conditions, return a ResultWrapper
 258          * which will return matching database rows with the
 259          * fields necessary to build Revision objects.
 260          *
 261          * @param $db DatabaseBase
 262          * @param $conditions Array
 263          * @return ResultWrapper
 264          */
 265         private static function fetchFromConds( $db, $conditions ) {
 266                 $fields = self::selectFields();
 267                 $fields[] = 'page_namespace';
 268                 $fields[] = 'page_title';
 269                 $fields[] = 'page_latest';
 270                 return $db->select(
 271                         array( 'page', 'revision' ),
 272                         $fields,
 273                         $conditions,
 274                         __METHOD__,
 275                         array( 'LIMIT' => 1 ) );
 276         }
 277
 278         /**
 279          * Return the list of revision fields that should be selected to create
 280          * a new revision.
 281          */
 282         public static function selectFields() {
 283                 return array(
 284                         'rev_id',
 285                         'rev_page',
 286                         'rev_text_id',
 287                         'rev_timestamp',
 288                         'rev_comment',
 289                         'rev_user_text,'.
 290                         'rev_user',
 291                         'rev_minor_edit',
 292                         'rev_deleted',
 293                         'rev_len',
 294                         'rev_parent_id'
 295                 );
 296         }
 297
 298         /**
 299          * Return the list of text fields that should be selected to read the
 300          * revision text
 301          */
 302         static function selectTextFields() {
 303                 return array(
 304                         'old_text',
 305                         'old_flags'
 306                 );
 307         }
 308
 309         /**
 310          * Return the list of page fields that should be selected from page table
 311          */
 312         static function selectPageFields() {
 313                 return array(
 314                         'page_namespace',
 315                         'page_title',
 316                         'page_latest'
 317                 );
 318         }
 319
 320         /**
 321          * Constructor
 322          *
 323          * @param $row Mixed: either a database row or an array
 324          * @access private
 325          */
 326         function __construct( $row ) {
 327                 if( is_object( $row ) ) {
 328                         $this->mId        = intval( $row->rev_id );
 329                         $this->mPage      = intval( $row->rev_page );
 330                         $this->mTextId    = intval( $row->rev_text_id );
 331                         $this->mComment   =         $row->rev_comment;
 332                         $this->mUserText  =         $row->rev_user_text;
 333                         $this->mUser      = intval( $row->rev_user );
 334                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 335                         $this->mTimestamp =         $row->rev_timestamp;
 336                         $this->mDeleted   = intval( $row->rev_deleted );
 337
 338                         if( !isset( $row->rev_parent_id ) )
 339                                 $this->mParentId = is_null($row->rev_parent_id) ? null : 0;
 340                         else
 341                                 $this->mParentId  = intval( $row->rev_parent_id );
 342
 343                         if( !isset( $row->rev_len ) || is_null( $row->rev_len ) )
 344                                 $this->mSize = null;
 345                         else
 346                                 $this->mSize = intval( $row->rev_len );
 347
 348                         if( isset( $row->page_latest ) ) {
 349                                 $this->mCurrent = ( $row->rev_id == $row->page_latest );
 350                                 $this->mTitle = Title::newFromRow( $row );
 351                         } else {
 352                                 $this->mCurrent = false;
 353                                 $this->mTitle = null;
 354                         }
 355
 356                         // Lazy extraction...
 357                         $this->mText      = null;
 358                         if( isset( $row->old_text ) ) {
 359                                 $this->mTextRow = $row;
 360                         } else {
 361                                 // 'text' table row entry will be lazy-loaded
 362                                 $this->mTextRow = null;
 363                         }
 364                 } elseif( is_array( $row ) ) {
 365                         // Build a new revision to be saved...
 366                         global $wgUser;
 367
 368                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 369                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 370                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 371                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 372                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 373                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 374                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestamp( TS_MW );
 375                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 376                         $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
 377                         $this->mParentId  = isset( $row['parent_id']  ) ? intval( $row['parent_id']  ) : null;
 378
 379                         // Enforce spacing trimming on supplied text
 380                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 381                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 382                         $this->mTextRow   = null;
 383
 384                         $this->mTitle     = null; # Load on demand if needed
 385                         $this->mCurrent   = false;
 386                         # If we still have no len_size, see it we have the text to figure it out
 387                         if ( !$this->mSize )
 388                                 $this->mSize      = is_null( $this->mText ) ? null : strlen( $this->mText );
 389                 } else {
 390                         throw new MWException( 'Revision constructor passed invalid row format.' );
 391                 }
 392                 $this->mUnpatrolled = null;
 393         }
 394
 395         /**
 396          * Get revision ID
 397          *
 398          * @return Integer
 399          */
 400         public function getId() {
 401                 return $this->mId;
 402         }
 403
 404         /**
 405          * Get text row ID
 406          *
 407          * @return Integer
 408          */
 409         public function getTextId() {
 410                 return $this->mTextId;
 411         }
 412
 413         /**
 414          * Get parent revision ID (the original previous page revision)
 415          *
 416          * @return Integer
 417          */
 418         public function getParentId() {
 419                 return $this->mParentId;
 420         }
 421
 422         /**
 423          * Returns the length of the text in this revision, or null if unknown.
 424          *
 425          * @return Integer
 426          */
 427         public function getSize() {
 428                 return $this->mSize;
 429         }
 430
 431         /**
 432          * Returns the title of the page associated with this entry.
 433          *
 434          * @return Title
 435          */
 436         public function getTitle() {
 437                 if( isset( $this->mTitle ) ) {
 438                         return $this->mTitle;
 439                 }
 440                 $dbr = wfGetDB( DB_SLAVE );
 441                 $row = $dbr->selectRow(
 442                         array( 'page', 'revision' ),
 443                         array( 'page_namespace', 'page_title' ),
 444                         array( 'page_id=rev_page',
 445                                    'rev_id' => $this->mId ),
 446                         'Revision::getTitle' );
 447                 if( $row ) {
 448                         $this->mTitle = Title::makeTitle( $row->page_namespace,
 449                                                                                           $row->page_title );
 450                 }
 451                 return $this->mTitle;
 452         }
 453
 454         /**
 455          * Set the title of the revision
 456          *
 457          * @param $title Title
 458          */
 459         public function setTitle( $title ) {
 460                 $this->mTitle = $title;
 461         }
 462
 463         /**
 464          * Get the page ID
 465          *
 466          * @return Integer
 467          */
 468         public function getPage() {
 469                 return $this->mPage;
 470         }
 471
 472         /**
 473          * Fetch revision's user id if it's available to the specified audience.
 474          * If the specified audience does not have access to it, zero will be
 475          * returned.
 476          *
 477          * @param $audience Integer: one of:
 478          *      Revision::FOR_PUBLIC       to be displayed to all users
 479          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 480          *      Revision::RAW              get the ID regardless of permissions
 481          *
 482          *
 483          * @return Integer
 484          */
 485         public function getUser( $audience = self::FOR_PUBLIC ) {
 486                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 487                         return 0;
 488                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER ) ) {
 489                         return 0;
 490                 } else {
 491                         return $this->mUser;
 492                 }
 493         }
 494
 495         /**
 496          * Fetch revision's user id without regard for the current user's permissions
 497          *
 498          * @return String
 499          */
 500         public function getRawUser() {
 501                 return $this->mUser;
 502         }
 503
 504         /**
 505          * Fetch revision's username if it's available to the specified audience.
 506          * If the specified audience does not have access to the username, an
 507          * empty string will be returned.
 508          *
 509          * @param $audience Integer: one of:
 510          *      Revision::FOR_PUBLIC       to be displayed to all users
 511          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 512          *      Revision::RAW              get the text regardless of permissions
 513          *
 514          * @return string
 515          */
 516         public function getUserText( $audience = self::FOR_PUBLIC ) {
 517                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 518                         return '';
 519                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER ) ) {
 520                         return '';
 521                 } else {
 522                         return $this->mUserText;
 523                 }
 524         }
 525
 526         /**
 527          * Fetch revision's username without regard for view restrictions
 528          *
 529          * @return String
 530          */
 531         public function getRawUserText() {
 532                 return $this->mUserText;
 533         }
 534
 535         /**
 536          * Fetch revision comment if it's available to the specified audience.
 537          * If the specified audience does not have access to the comment, an
 538          * empty string will be returned.
 539          *
 540          * @param $audience Integer: one of:
 541          *      Revision::FOR_PUBLIC       to be displayed to all users
 542          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 543          *      Revision::RAW              get the text regardless of permissions
 544          *
 545          * @return String
 546          */
 547         function getComment( $audience = self::FOR_PUBLIC ) {
 548                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_COMMENT ) ) {
 549                         return '';
 550                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_COMMENT ) ) {
 551                         return '';
 552                 } else {
 553                         return $this->mComment;
 554                 }
 555         }
 556
 557         /**
 558          * Fetch revision comment without regard for the current user's permissions
 559          *
 560          * @return String
 561          */
 562         public function getRawComment() {
 563                 return $this->mComment;
 564         }
 565
 566         /**
 567          * @return Boolean
 568          */
 569         public function isMinor() {
 570                 return (bool)$this->mMinorEdit;
 571         }
 572
 573         /**
 574          * @return Integer rcid of the unpatrolled row, zero if there isn't one
 575          */
 576         public function isUnpatrolled() {
 577                 if( $this->mUnpatrolled !== null ) {
 578                         return $this->mUnpatrolled;
 579                 }
 580                 $dbr = wfGetDB( DB_SLAVE );
 581                 $this->mUnpatrolled = $dbr->selectField( 'recentchanges',
 582                         'rc_id',
 583                         array( // Add redundant user,timestamp condition so we can use the existing index
 584                                 'rc_user_text'  => $this->getRawUserText(),
 585                                 'rc_timestamp'  => $dbr->timestamp( $this->getTimestamp() ),
 586                                 'rc_this_oldid' => $this->getId(),
 587                                 'rc_patrolled'  => 0
 588                         ),
 589                         __METHOD__
 590                 );
 591                 return (int)$this->mUnpatrolled;
 592         }
 593
 594         /**
 595          * int $field one of DELETED_* bitfield constants
 596          *
 597          * @return Boolean
 598          */
 599         public function isDeleted( $field ) {
 600                 return ( $this->mDeleted & $field ) == $field;
 601         }
 602
 603         /**
 604          * Get the deletion bitfield of the revision
 605          */
 606         public function getVisibility() {
 607                 return (int)$this->mDeleted;
 608         }
 609
 610         /**
 611          * Fetch revision text if it's available to the specified audience.
 612          * If the specified audience does not have the ability to view this
 613          * revision, an empty string will be returned.
 614          *
 615          * @param $audience Integer: one of:
 616          *      Revision::FOR_PUBLIC       to be displayed to all users
 617          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 618          *      Revision::RAW              get the text regardless of permissions
 619          *
 620          * @return String
 621          */
 622         public function getText( $audience = self::FOR_PUBLIC ) {
 623                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_TEXT ) ) {
 624                         return '';
 625                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_TEXT ) ) {
 626                         return '';
 627                 } else {
 628                         return $this->getRawText();
 629                 }
 630         }
 631
 632         /**
 633          * Alias for getText(Revision::FOR_THIS_USER)
 634          *
 635          * @deprecated since 1.17
 636          * @return String
 637          */
 638         public function revText() {
 639                 wfDeprecated( __METHOD__ );
 640                 return $this->getText( self::FOR_THIS_USER );
 641         }
 642
 643         /**
 644          * Fetch revision text without regard for view restrictions
 645          *
 646          * @return String
 647          */
 648         public function getRawText() {
 649                 if( is_null( $this->mText ) ) {
 650                         // Revision text is immutable. Load on demand:
 651                         $this->mText = $this->loadText();
 652                 }
 653                 return $this->mText;
 654         }
 655
 656         /**
 657          * @return String
 658          */
 659         public function getTimestamp() {
 660                 return wfTimestamp( TS_MW, $this->mTimestamp );
 661         }
 662
 663         /**
 664          * @return Boolean
 665          */
 666         public function isCurrent() {
 667                 return $this->mCurrent;
 668         }
 669
 670         /**
 671          * Get previous revision for this title
 672          *
 673          * @return Revision or null
 674          */
 675         public function getPrevious() {
 676                 if( $this->getTitle() ) {
 677                         $prev = $this->getTitle()->getPreviousRevisionID( $this->getId() );
 678                         if( $prev ) {
 679                                 return Revision::newFromTitle( $this->getTitle(), $prev );
 680                         }
 681                 }
 682                 return null;
 683         }
 684
 685         /**
 686          * Get next revision for this title
 687          *
 688          * @return Revision or null
 689          */
 690         public function getNext() {
 691                 if( $this->getTitle() ) {
 692                         $next = $this->getTitle()->getNextRevisionID( $this->getId() );
 693                         if ( $next ) {
 694                                 return Revision::newFromTitle( $this->getTitle(), $next );
 695                         }
 696                 }
 697                 return null;
 698         }
 699
 700         /**
 701          * Get previous revision Id for this page_id
 702          * This is used to populate rev_parent_id on save
 703          *
 704          * @param $db DatabaseBase
 705          * @return Integer
 706          */
 707         private function getPreviousRevisionId( $db ) {
 708                 if( is_null( $this->mPage ) ) {
 709                         return 0;
 710                 }
 711                 # Use page_latest if ID is not given
 712                 if( !$this->mId ) {
 713                         $prevId = $db->selectField( 'page', 'page_latest',
 714                                 array( 'page_id' => $this->mPage ),
 715                                 __METHOD__ );
 716                 } else {
 717                         $prevId = $db->selectField( 'revision', 'rev_id',
 718                                 array( 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ),
 719                                 __METHOD__,
 720                                 array( 'ORDER BY' => 'rev_id DESC' ) );
 721                 }
 722                 return intval( $prevId );
 723         }
 724
 725         /**
 726           * Get revision text associated with an old or archive row
 727           * $row is usually an object from wfFetchRow(), both the flags and the text
 728           * field must be included
 729           *
 730           * @param $row Object: the text data
 731           * @param $prefix String: table prefix (default 'old_')
 732           * @return String: text the text requested or false on failure
 733           */
 734         public static function getRevisionText( $row, $prefix = 'old_' ) {
 735                 wfProfileIn( __METHOD__ );
 736
 737                 # Get data
 738                 $textField = $prefix . 'text';
 739                 $flagsField = $prefix . 'flags';
 740
 741                 if( isset( $row->$flagsField ) ) {
 742                         $flags = explode( ',', $row->$flagsField );
 743                 } else {
 744                         $flags = array();
 745                 }
 746
 747                 if( isset( $row->$textField ) ) {
 748                         $text = $row->$textField;
 749                 } else {
 750                         wfProfileOut( __METHOD__ );
 751                         return false;
 752                 }
 753
 754                 # Use external methods for external objects, text in table is URL-only then
 755                 if ( in_array( 'external', $flags ) ) {
 756                         $url = $text;
 757                         $parts = explode( '://', $url, 2 );
 758                         if( count( $parts ) == 1 || $parts[1] == '' ) {
 759                                 wfProfileOut( __METHOD__ );
 760                                 return false;
 761                         }
 762                         $text = ExternalStore::fetchFromURL( $url );
 763                 }
 764
 765                 // If the text was fetched without an error, convert it
 766                 if ( $text !== false ) {
 767                         if( in_array( 'gzip', $flags ) ) {
 768                                 # Deal with optional compression of archived pages.
 769                                 # This can be done periodically via maintenance/compressOld.php, and
 770                                 # as pages are saved if $wgCompressRevisions is set.
 771                                 $text = gzinflate( $text );
 772                         }
 773
 774                         if( in_array( 'object', $flags ) ) {
 775                                 # Generic compressed storage
 776                                 $obj = unserialize( $text );
 777                                 if ( !is_object( $obj ) ) {
 778                                         // Invalid object
 779                                         wfProfileOut( __METHOD__ );
 780                                         return false;
 781                                 }
 782                                 $text = $obj->getText();
 783                         }
 784
 785                         global $wgLegacyEncoding;
 786                         if( $text !== false && $wgLegacyEncoding
 787                                 && !in_array( 'utf-8', $flags ) && !in_array( 'utf8', $flags ) )
 788                         {
 789                                 # Old revisions kept around in a legacy encoding?
 790                                 # Upconvert on demand.
 791                                 # ("utf8" checked for compatibility with some broken
 792                                 #  conversion scripts 2008-12-30)
 793                                 global $wgContLang;
 794                                 $text = $wgContLang->iconv( $wgLegacyEncoding, 'UTF-8', $text );
 795                         }
 796                 }
 797                 wfProfileOut( __METHOD__ );
 798                 return $text;
 799         }
 800
 801         /**
 802          * If $wgCompressRevisions is enabled, we will compress data.
 803          * The input string is modified in place.
 804          * Return value is the flags field: contains 'gzip' if the
 805          * data is compressed, and 'utf-8' if we're saving in UTF-8
 806          * mode.
 807          *
 808          * @param $text Mixed: reference to a text
 809          * @return String
 810          */
 811         public static function compressRevisionText( &$text ) {
 812                 global $wgCompressRevisions;
 813                 $flags = array();
 814
 815                 # Revisions not marked this way will be converted
 816                 # on load if $wgLegacyCharset is set in the future.
 817                 $flags[] = 'utf-8';
 818
 819                 if( $wgCompressRevisions ) {
 820                         if( function_exists( 'gzdeflate' ) ) {
 821                                 $text = gzdeflate( $text );
 822                                 $flags[] = 'gzip';
 823                         } else {
 824                                 wfDebug( "Revision::compressRevisionText() -- no zlib support, not compressing\n" );
 825                         }
 826                 }
 827                 return implode( ',', $flags );
 828         }
 829
 830         /**
 831          * Insert a new revision into the database, returning the new revision ID
 832          * number on success and dies horribly on failure.
 833          *
 834          * @param $dbw DatabaseBase: (master connection)
 835          * @return Integer
 836          */
 837         public function insertOn( $dbw ) {
 838                 global $wgDefaultExternalStore;
 839
 840                 wfProfileIn( __METHOD__ );
 841
 842                 $data = $this->mText;
 843                 $flags = Revision::compressRevisionText( $data );
 844
 845                 # Write to external storage if required
 846                 if( $wgDefaultExternalStore ) {
 847                         // Store and get the URL
 848                         $data = ExternalStore::insertToDefault( $data );
 849                         if( !$data ) {
 850                                 throw new MWException( "Unable to store text to external storage" );
 851                         }
 852                         if( $flags ) {
 853                                 $flags .= ',';
 854                         }
 855                         $flags .= 'external';
 856                 }
 857
 858                 # Record the text (or external storage URL) to the text table
 859                 if( !isset( $this->mTextId ) ) {
 860                         $old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );
 861                         $dbw->insert( 'text',
 862                                 array(
 863                                         'old_id'    => $old_id,
 864                                         'old_text'  => $data,
 865                                         'old_flags' => $flags,
 866                                 ), __METHOD__
 867                         );
 868                         $this->mTextId = $dbw->insertId();
 869                 }
 870
 871                 if ( $this->mComment === null ) $this->mComment = "";
 872
 873                 # Record the edit in revisions
 874                 $rev_id = isset( $this->mId )
 875                         ? $this->mId
 876                         : $dbw->nextSequenceValue( 'revision_rev_id_seq' );
 877                 $dbw->insert( 'revision',
 878                         array(
 879                                 'rev_id'         => $rev_id,
 880                                 'rev_page'       => $this->mPage,
 881                                 'rev_text_id'    => $this->mTextId,
 882                                 'rev_comment'    => $this->mComment,
 883                                 'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
 884                                 'rev_user'       => $this->mUser,
 885                                 'rev_user_text'  => $this->mUserText,
 886                                 'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
 887                                 'rev_deleted'    => $this->mDeleted,
 888                                 'rev_len'        => $this->mSize,
 889                                 'rev_parent_id'  => is_null($this->mParentId) ?
 890                                         $this->getPreviousRevisionId( $dbw ) : $this->mParentId
 891                         ), __METHOD__
 892                 );
 893
 894                 $this->mId = !is_null( $rev_id ) ? $rev_id : $dbw->insertId();
 895
 896                 wfRunHooks( 'RevisionInsertComplete', array( &$this, $data, $flags ) );
 897
 898                 wfProfileOut( __METHOD__ );
 899                 return $this->mId;
 900         }
 901
 902         /**
 903          * Lazy-load the revision's text.
 904          * Currently hardcoded to the 'text' table storage engine.
 905          *
 906          * @return String
 907          */
 908         protected function loadText() {
 909                 wfProfileIn( __METHOD__ );
 910
 911                 // Caching may be beneficial for massive use of external storage
 912                 global $wgRevisionCacheExpiry, $wgMemc;
 913                 $textId = $this->getTextId();
 914                 $key = wfMemcKey( 'revisiontext', 'textid', $textId );
 915                 if( $wgRevisionCacheExpiry ) {
 916                         $text = $wgMemc->get( $key );
 917                         if( is_string( $text ) ) {
 918                                 wfDebug( __METHOD__ . ": got id $textId from cache\n" );
 919                                 wfProfileOut( __METHOD__ );
 920                                 return $text;
 921                         }
 922                 }
 923
 924                 // If we kept data for lazy extraction, use it now...
 925                 if ( isset( $this->mTextRow ) ) {
 926                         $row = $this->mTextRow;
 927                         $this->mTextRow = null;
 928                 } else {
 929                         $row = null;
 930                 }
 931
 932                 if( !$row ) {
 933                         // Text data is immutable; check slaves first.
 934                         $dbr = wfGetDB( DB_SLAVE );
 935                         $row = $dbr->selectRow( 'text',
 936                                 array( 'old_text', 'old_flags' ),
 937                                 array( 'old_id' => $this->getTextId() ),
 938                                 __METHOD__ );
 939                 }
 940
 941                 if( !$row && wfGetLB()->getServerCount() > 1 ) {
 942                         // Possible slave lag!
 943                         $dbw = wfGetDB( DB_MASTER );
 944                         $row = $dbw->selectRow( 'text',
 945                                 array( 'old_text', 'old_flags' ),
 946                                 array( 'old_id' => $this->getTextId() ),
 947                                 __METHOD__ );
 948                 }
 949
 950                 $text = self::getRevisionText( $row );
 951
 952                 # No negative caching -- negative hits on text rows may be due to corrupted slave servers
 953                 if( $wgRevisionCacheExpiry && $text !== false ) {
 954                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
 955                 }
 956
 957                 wfProfileOut( __METHOD__ );
 958
 959                 return $text;
 960         }
 961
 962         /**
 963          * Create a new null-revision for insertion into a page's
 964          * history. This will not re-save the text, but simply refer
 965          * to the text from the previous version.
 966          *
 967          * Such revisions can for instance identify page rename
 968          * operations and other such meta-modifications.
 969          *
 970          * @param $dbw DatabaseBase
 971          * @param $pageId Integer: ID number of the page to read from
 972          * @param $summary String: revision's summary
 973          * @param $minor Boolean: whether the revision should be considered as minor
 974          * @return Revision|null on error
 975          */
 976         public static function newNullRevision( $dbw, $pageId, $summary, $minor ) {
 977                 wfProfileIn( __METHOD__ );
 978
 979                 $current = $dbw->selectRow(
 980                         array( 'page', 'revision' ),
 981                         array( 'page_latest', 'rev_text_id', 'rev_len' ),
 982                         array(
 983                                 'page_id' => $pageId,
 984                                 'page_latest=rev_id',
 985                                 ),
 986                         __METHOD__ );
 987
 988                 if( $current ) {
 989                         $revision = new Revision( array(
 990                                 'page'       => $pageId,
 991                                 'comment'    => $summary,
 992                                 'minor_edit' => $minor,
 993                                 'text_id'    => $current->rev_text_id,
 994                                 'parent_id'  => $current->page_latest,
 995                                 'len'        => $current->rev_len
 996                                 ) );
 997                 } else {
 998                         $revision = null;
 999                 }
1000
1001                 wfProfileOut( __METHOD__ );
1002                 return $revision;
1003         }
1004
1005         /**
1006          * Determine if the current user is allowed to view a particular
1007          * field of this revision, if it's marked as deleted.
1008          *
1009          * @param $field Integer:one of self::DELETED_TEXT,
1010          *                              self::DELETED_COMMENT,
1011          *                              self::DELETED_USER
1012          * @return Boolean
1013          */
1014         public function userCan( $field ) {
1015                 return self::userCanBitfield( $this->mDeleted, $field );
1016         }
1017
1018         /**
1019          * Determine if the current user is allowed to view a particular
1020          * field of this revision, if it's marked as deleted. This is used
1021          * by various classes to avoid duplication.
1022          *
1023          * @param $bitfield Integer: current field
1024          * @param $field Integer: one of self::DELETED_TEXT = File::DELETED_FILE,
1025          *                               self::DELETED_COMMENT = File::DELETED_COMMENT,
1026          *                               self::DELETED_USER = File::DELETED_USER
1027          * @return Boolean
1028          */
1029         public static function userCanBitfield( $bitfield, $field ) {
1030                 if( $bitfield & $field ) { // aspect is deleted
1031                         global $wgUser;
1032                         if ( $bitfield & self::DELETED_RESTRICTED ) {
1033                                 $permission = 'suppressrevision';
1034                         } elseif ( $field & self::DELETED_TEXT ) {
1035                                 $permission = 'deletedtext';
1036                         } else {
1037                                 $permission = 'deletedhistory';
1038                         }
1039                         wfDebug( "Checking for $permission due to $field match on $bitfield\n" );
1040                         return $wgUser->isAllowed( $permission );
1041                 } else {
1042                         return true;
1043                 }
1044         }
1045
1046         /**
1047          * Get rev_timestamp from rev_id, without loading the rest of the row
1048          *
1049          * @param $title Title
1050          * @param $id Integer
1051          * @return String
1052          */
1053         static function getTimestampFromId( $title, $id ) {
1054                 $dbr = wfGetDB( DB_SLAVE );
1055                 // Casting fix for DB2
1056                 if ( $id == '' ) {
1057                         $id = 0;
1058                 }
1059                 $conds = array( 'rev_id' => $id );
1060                 $conds['rev_page'] = $title->getArticleId();
1061                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1062                 if ( $timestamp === false && wfGetLB()->getServerCount() > 1 ) {
1063                         # Not in slave, try master
1064                         $dbw = wfGetDB( DB_MASTER );
1065                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1066                 }
1067                 return wfTimestamp( TS_MW, $timestamp );
1068         }
1069
1070         /**
1071          * Get count of revisions per page...not very efficient
1072          *
1073          * @param $db DatabaseBase
1074          * @param $id Integer: page id
1075          * @return Integer
1076          */
1077         static function countByPageId( $db, $id ) {
1078                 $row = $db->selectRow( 'revision', 'COUNT(*) AS revCount',
1079                         array( 'rev_page' => $id ), __METHOD__ );
1080                 if( $row ) {
1081                         return $row->revCount;
1082                 }
1083                 return 0;
1084         }
1085
1086         /**
1087          * Get count of revisions per page...not very efficient
1088          *
1089          * @param $db DatabaseBase
1090          * @param $title Title
1091          * @return Integer
1092          */
1093         static function countByTitle( $db, $title ) {
1094                 $id = $title->getArticleId();
1095                 if( $id ) {
1096                         return Revision::countByPageId( $db, $id );
1097                 }
1098                 return 0;
1099         }
1100 }
1101
1102 /**
1103  * Aliases for backwards compatibility with 1.6
1104  */
1105 define( 'MW_REV_DELETED_TEXT', Revision::DELETED_TEXT );
1106 define( 'MW_REV_DELETED_COMMENT', Revision::DELETED_COMMENT );
1107 define( 'MW_REV_DELETED_USER', Revision::DELETED_USER );
1108 define( 'MW_REV_DELETED_RESTRICTED', Revision::DELETED_RESTRICTED );