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( array( 'rev_id' => intval( $id ) ) );
  27         }
  28
  29         /**
  30          * Load either the current, or a specified, revision
  31          * that's attached to a given title. If not attached
  32          * to that title, will return null.
  33          *
  34          * @param $title Title
  35          * @param $id Integer (optional)
  36          * @return Revision or null
  37          */
  38         public static function newFromTitle( $title, $id = 0 ) {
  39                 $conds = array(
  40                         'page_namespace' => $title->getNamespace(),
  41                         'page_title'     => $title->getDBkey()
  42                 );
  43                 if ( $id ) {
  44                         // Use the specified ID
  45                         $conds['rev_id'] = $id;
  46                 } elseif ( wfGetLB()->getServerCount() > 1 ) {
  47                         // Get the latest revision ID from the master
  48                         $dbw = wfGetDB( DB_MASTER );
  49                         $latest = $dbw->selectField( 'page', 'page_latest', $conds, __METHOD__ );
  50                         if ( $latest === false ) {
  51                                 return null; // page does not exist
  52                         }
  53                         $conds['rev_id'] = $latest;
  54                 } else {
  55                         // Use a join to get the latest revision
  56                         $conds[] = 'rev_id=page_latest';
  57                 }
  58                 return Revision::newFromConds( $conds );
  59         }
  60
  61         /**
  62          * Load either the current, or a specified, revision
  63          * that's attached to a given page ID.
  64          * Returns null if no such revision can be found.
  65          *
  66          * @param $revId Integer
  67          * @param $pageId Integer (optional)
  68          * @return Revision or null
  69          */
  70         public static function newFromPageId( $pageId, $revId = 0 ) {
  71                 $conds = array( 'page_id' => $pageId );
  72                 if ( $revId ) {
  73                         $conds['rev_id'] = $revId;
  74                 } elseif ( wfGetLB()->getServerCount() > 1 ) {
  75                         // Get the latest revision ID from the master
  76                         $dbw = wfGetDB( DB_MASTER );
  77                         $latest = $dbw->selectField( 'page', 'page_latest', $conds, __METHOD__ );
  78                         if ( $latest === false ) {
  79                                 return null; // page does not exist
  80                         }
  81                         $conds['rev_id'] = $latest;
  82                 } else {
  83                         $conds[] = 'rev_id = page_latest';
  84                 }
  85                 return Revision::newFromConds( $conds );
  86         }
  87
  88         /**
  89          * Make a fake revision object from an archive table row. This is queried
  90          * for permissions or even inserted (as in Special:Undelete)
  91          * @todo FIXME: Should be a subclass for RevisionDelete. [TS]
  92          *
  93          * @param $row
  94          * @param $overrides array
  95          *
  96          * @return Revision
  97          */
  98         public static function newFromArchiveRow( $row, $overrides = array() ) {
  99                 $attribs = $overrides + array(
 100                         'page'       => isset( $row->ar_page_id ) ? $row->ar_page_id : null,
 101                         'id'         => isset( $row->ar_rev_id ) ? $row->ar_rev_id : null,
 102                         'comment'    => $row->ar_comment,
 103                         'user'       => $row->ar_user,
 104                         'user_text'  => $row->ar_user_text,
 105                         'timestamp'  => $row->ar_timestamp,
 106                         'minor_edit' => $row->ar_minor_edit,
 107                         'text_id'    => isset( $row->ar_text_id ) ? $row->ar_text_id : null,
 108                         'deleted'    => $row->ar_deleted,
 109                         'len'        => $row->ar_len
 110                 );
 111                 if ( isset( $row->ar_text ) && !$row->ar_text_id ) {
 112                         // Pre-1.5 ar_text row
 113                         $attribs['text'] = self::getRevisionText( $row, 'ar_' );
 114                         if ( $attribs['text'] === false ) {
 115                                 throw new MWException( 'Unable to load text from archive row (possibly bug 22624)' );
 116                         }
 117                 }
 118                 return new self( $attribs );
 119         }
 120
 121         /**
 122          * @since 1.19
 123          *
 124          * @param $row
 125          * @return Revision
 126          */
 127         public static function newFromRow( $row ) {
 128                 return new self( $row );
 129         }
 130
 131         /**
 132          * Load a page revision from a given revision ID number.
 133          * Returns null if no such revision can be found.
 134          *
 135          * @param $db DatabaseBase
 136          * @param $id Integer
 137          * @return Revision or null
 138          */
 139         public static function loadFromId( $db, $id ) {
 140                 return Revision::loadFromConds( $db, array( 'rev_id' => intval( $id ) ) );
 141         }
 142
 143         /**
 144          * Load either the current, or a specified, revision
 145          * that's attached to a given page. If not attached
 146          * to that page, will return null.
 147          *
 148          * @param $db DatabaseBase
 149          * @param $pageid Integer
 150          * @param $id Integer
 151          * @return Revision or null
 152          */
 153         public static function loadFromPageId( $db, $pageid, $id = 0 ) {
 154                 $conds = array( 'rev_page' => intval( $pageid ), 'page_id'  => intval( $pageid ) );
 155                 if( $id ) {
 156                         $conds['rev_id'] = intval( $id );
 157                 } else {
 158                         $conds[] = 'rev_id=page_latest';
 159                 }
 160                 return Revision::loadFromConds( $db, $conds );
 161         }
 162
 163         /**
 164          * Load either the current, or a specified, revision
 165          * that's attached to a given page. If not attached
 166          * to that page, will return null.
 167          *
 168          * @param $db DatabaseBase
 169          * @param $title Title
 170          * @param $id Integer
 171          * @return Revision or null
 172          */
 173         public static function loadFromTitle( $db, $title, $id = 0 ) {
 174                 if( $id ) {
 175                         $matchId = intval( $id );
 176                 } else {
 177                         $matchId = 'page_latest';
 178                 }
 179                 return Revision::loadFromConds( $db,
 180                         array( "rev_id=$matchId",
 181                                    'page_namespace' => $title->getNamespace(),
 182                                    'page_title'     => $title->getDBkey() )
 183                 );
 184         }
 185
 186         /**
 187          * Load the revision for the given title with the given timestamp.
 188          * WARNING: Timestamps may in some circumstances not be unique,
 189          * so this isn't the best key to use.
 190          *
 191          * @param $db DatabaseBase
 192          * @param $title Title
 193          * @param $timestamp String
 194          * @return Revision or null
 195          */
 196         public static function loadFromTimestamp( $db, $title, $timestamp ) {
 197                 return Revision::loadFromConds( $db,
 198                         array( 'rev_timestamp'  => $db->timestamp( $timestamp ),
 199                                    'page_namespace' => $title->getNamespace(),
 200                                    'page_title'     => $title->getDBkey() )
 201                 );
 202         }
 203
 204         /**
 205          * Given a set of conditions, fetch a revision.
 206          *
 207          * @param $conditions Array
 208          * @return Revision or null
 209          */
 210         public static function newFromConds( $conditions ) {
 211                 $db = wfGetDB( DB_SLAVE );
 212                 $rev = Revision::loadFromConds( $db, $conditions );
 213                 if( is_null( $rev ) && wfGetLB()->getServerCount() > 1 ) {
 214                         $dbw = wfGetDB( DB_MASTER );
 215                         $rev = Revision::loadFromConds( $dbw, $conditions );
 216                 }
 217                 return $rev;
 218         }
 219
 220         /**
 221          * Given a set of conditions, fetch a revision from
 222          * the given database connection.
 223          *
 224          * @param $db DatabaseBase
 225          * @param $conditions Array
 226          * @return Revision or null
 227          */
 228         private static function loadFromConds( $db, $conditions ) {
 229                 $res = Revision::fetchFromConds( $db, $conditions );
 230                 if( $res ) {
 231                         $row = $res->fetchObject();
 232                         if( $row ) {
 233                                 $ret = new Revision( $row );
 234                                 return $ret;
 235                         }
 236                 }
 237                 $ret = null;
 238                 return $ret;
 239         }
 240
 241         /**
 242          * Return a wrapper for a series of database rows to
 243          * fetch all of a given page's revisions in turn.
 244          * Each row can be fed to the constructor to get objects.
 245          *
 246          * @param $title Title
 247          * @return ResultWrapper
 248          */
 249         public static function fetchRevision( $title ) {
 250                 return Revision::fetchFromConds(
 251                         wfGetDB( DB_SLAVE ),
 252                         array( 'rev_id=page_latest',
 253                                    'page_namespace' => $title->getNamespace(),
 254                                    'page_title'     => $title->getDBkey() )
 255                 );
 256         }
 257
 258         /**
 259          * Given a set of conditions, return a ResultWrapper
 260          * which will return matching database rows with the
 261          * fields necessary to build Revision objects.
 262          *
 263          * @param $db DatabaseBase
 264          * @param $conditions Array
 265          * @return ResultWrapper
 266          */
 267         private static function fetchFromConds( $db, $conditions ) {
 268                 $fields = array_merge(
 269                         self::selectFields(),
 270                         self::selectPageFields(),
 271                         self::selectUserFields()
 272                 );
 273                 return $db->select(
 274                         array( 'revision', 'page', 'user' ),
 275                         $fields,
 276                         $conditions,
 277                         __METHOD__,
 278                         array( 'LIMIT' => 1 ),
 279                         array( 'page' => array( 'INNER JOIN', 'page_id = rev_page' ),
 280                                 'user' => array( 'LEFT JOIN', 'rev_user != 0 AND user_id = rev_user' ) )
 281                 );
 282         }
 283
 284         /**
 285          * Return the list of revision fields that should be selected to create
 286          * a new revision.
 287          */
 288         public static function selectFields() {
 289                 return array(
 290                         'rev_id',
 291                         'rev_page',
 292                         'rev_text_id',
 293                         'rev_timestamp',
 294                         'rev_comment',
 295                         'rev_user_text',
 296                         'rev_user',
 297                         'rev_minor_edit',
 298                         'rev_deleted',
 299                         'rev_len',
 300                         'rev_parent_id'
 301                 );
 302         }
 303
 304         /**
 305          * Return the list of text fields that should be selected to read the
 306          * revision text
 307          */
 308         public static function selectTextFields() {
 309                 return array(
 310                         'old_text',
 311                         'old_flags'
 312                 );
 313         }
 314
 315         /**
 316          * Return the list of page fields that should be selected from page table
 317          */
 318         public static function selectPageFields() {
 319                 return array(
 320                         'page_namespace',
 321                         'page_title',
 322                         'page_latest'
 323                 );
 324         }
 325
 326         /**
 327          * Return the list of user fields that should be selected from user table
 328          */
 329         public static function selectUserFields() {
 330                 return array( 'user_name' );
 331         }
 332
 333         /**
 334          * Constructor
 335          *
 336          * @param $row Mixed: either a database row or an array
 337          * @access private
 338          */
 339         function __construct( $row ) {
 340                 if( is_object( $row ) ) {
 341                         $this->mId        = intval( $row->rev_id );
 342                         $this->mPage      = intval( $row->rev_page );
 343                         $this->mTextId    = intval( $row->rev_text_id );
 344                         $this->mComment   =         $row->rev_comment;
 345                         $this->mUser      = intval( $row->rev_user );
 346                         $this->mMinorEdit = intval( $row->rev_minor_edit );
 347                         $this->mTimestamp =         $row->rev_timestamp;
 348                         $this->mDeleted   = intval( $row->rev_deleted );
 349
 350                         if( !isset( $row->rev_parent_id ) ) {
 351                                 $this->mParentId = is_null($row->rev_parent_id) ? null : 0;
 352                         } else {
 353                                 $this->mParentId  = intval( $row->rev_parent_id );
 354                         }
 355
 356                         if( !isset( $row->rev_len ) || is_null( $row->rev_len ) ) {
 357                                 $this->mSize = null;
 358                         } else {
 359                                 $this->mSize = intval( $row->rev_len );
 360                         }
 361
 362                         if( isset( $row->page_latest ) ) {
 363                                 $this->mCurrent = ( $row->rev_id == $row->page_latest );
 364                                 $this->mTitle = Title::newFromRow( $row );
 365                         } else {
 366                                 $this->mCurrent = false;
 367                                 $this->mTitle = null;
 368                         }
 369
 370                         // Lazy extraction...
 371                         $this->mText      = null;
 372                         if( isset( $row->old_text ) ) {
 373                                 $this->mTextRow = $row;
 374                         } else {
 375                                 // 'text' table row entry will be lazy-loaded
 376                                 $this->mTextRow = null;
 377                         }
 378
 379                         // Use user_name for users and rev_user_text for IPs.
 380                         // Also fallback to rev_user_text if user_name not given.
 381                         if ( isset( $row->user_name ) ) {
 382                                 $this->mUserText = $row->user_name; // logged-in user (ideally)
 383                         } else {
 384                                 $this->mUserText = $row->rev_user_text; // IP user (ideally)
 385                         }
 386                 } elseif( is_array( $row ) ) {
 387                         // Build a new revision to be saved...
 388                         global $wgUser;
 389
 390                         $this->mId        = isset( $row['id']         ) ? intval( $row['id']         ) : null;
 391                         $this->mPage      = isset( $row['page']       ) ? intval( $row['page']       ) : null;
 392                         $this->mTextId    = isset( $row['text_id']    ) ? intval( $row['text_id']    ) : null;
 393                         $this->mUserText  = isset( $row['user_text']  ) ? strval( $row['user_text']  ) : $wgUser->getName();
 394                         $this->mUser      = isset( $row['user']       ) ? intval( $row['user']       ) : $wgUser->getId();
 395                         $this->mMinorEdit = isset( $row['minor_edit'] ) ? intval( $row['minor_edit'] ) : 0;
 396                         $this->mTimestamp = isset( $row['timestamp']  ) ? strval( $row['timestamp']  ) : wfTimestamp( TS_MW );
 397                         $this->mDeleted   = isset( $row['deleted']    ) ? intval( $row['deleted']    ) : 0;
 398                         $this->mSize      = isset( $row['len']        ) ? intval( $row['len']        ) : null;
 399                         $this->mParentId  = isset( $row['parent_id']  ) ? intval( $row['parent_id']  ) : null;
 400
 401                         // Enforce spacing trimming on supplied text
 402                         $this->mComment   = isset( $row['comment']    ) ?  trim( strval( $row['comment'] ) ) : null;
 403                         $this->mText      = isset( $row['text']       ) ? rtrim( strval( $row['text']    ) ) : null;
 404                         $this->mTextRow   = null;
 405
 406                         $this->mTitle     = null; # Load on demand if needed
 407                         $this->mCurrent   = false;
 408                         # If we still have no len_size, see it we have the text to figure it out
 409                         if ( !$this->mSize ) {
 410                                 $this->mSize      = is_null( $this->mText ) ? null : strlen( $this->mText );
 411                         }
 412                 } else {
 413                         throw new MWException( 'Revision constructor passed invalid row format.' );
 414                 }
 415                 $this->mUnpatrolled = null;
 416         }
 417
 418         /**
 419          * Get revision ID
 420          *
 421          * @return Integer
 422          */
 423         public function getId() {
 424                 return $this->mId;
 425         }
 426
 427         /**
 428          * Get text row ID
 429          *
 430          * @return Integer
 431          */
 432         public function getTextId() {
 433                 return $this->mTextId;
 434         }
 435
 436         /**
 437          * Get parent revision ID (the original previous page revision)
 438          *
 439          * @return Integer
 440          */
 441         public function getParentId() {
 442                 return $this->mParentId;
 443         }
 444
 445         /**
 446          * Returns the length of the text in this revision, or null if unknown.
 447          *
 448          * @return Integer
 449          */
 450         public function getSize() {
 451                 return $this->mSize;
 452         }
 453
 454         /**
 455          * Returns the title of the page associated with this entry.
 456          *
 457          * @return Title
 458          */
 459         public function getTitle() {
 460                 if( isset( $this->mTitle ) ) {
 461                         return $this->mTitle;
 462                 }
 463                 $dbr = wfGetDB( DB_SLAVE );
 464                 $row = $dbr->selectRow(
 465                         array( 'page', 'revision' ),
 466                         array( 'page_namespace', 'page_title' ),
 467                         array( 'page_id=rev_page',
 468                                    'rev_id' => $this->mId ),
 469                         'Revision::getTitle' );
 470                 if( $row ) {
 471                         $this->mTitle = Title::makeTitle( $row->page_namespace, $row->page_title );
 472                 }
 473                 return $this->mTitle;
 474         }
 475
 476         /**
 477          * Set the title of the revision
 478          *
 479          * @param $title Title
 480          */
 481         public function setTitle( $title ) {
 482                 $this->mTitle = $title;
 483         }
 484
 485         /**
 486          * Get the page ID
 487          *
 488          * @return Integer
 489          */
 490         public function getPage() {
 491                 return $this->mPage;
 492         }
 493
 494         /**
 495          * Fetch revision's user id if it's available to the specified audience.
 496          * If the specified audience does not have access to it, zero will be
 497          * returned.
 498          *
 499          * @param $audience Integer: one of:
 500          *      Revision::FOR_PUBLIC       to be displayed to all users
 501          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 502          *      Revision::RAW              get the ID regardless of permissions
 503          * @param $user User object to check for, only if FOR_THIS_USER is passed
 504          *              to the $audience parameter
 505          * @return Integer
 506          */
 507         public function getUser( $audience = self::FOR_PUBLIC, User $user = null ) {
 508                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 509                         return 0;
 510                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
 511                         return 0;
 512                 } else {
 513                         return $this->mUser;
 514                 }
 515         }
 516
 517         /**
 518          * Fetch revision's user id without regard for the current user's permissions
 519          *
 520          * @return String
 521          */
 522         public function getRawUser() {
 523                 return $this->mUser;
 524         }
 525
 526         /**
 527          * Fetch revision's username if it's available to the specified audience.
 528          * If the specified audience does not have access to the username, an
 529          * empty string will be returned.
 530          *
 531          * @param $audience Integer: one of:
 532          *      Revision::FOR_PUBLIC       to be displayed to all users
 533          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 534          *      Revision::RAW              get the text regardless of permissions
 535          * @param $user User object to check for, only if FOR_THIS_USER is passed
 536          *              to the $audience parameter
 537          * @return string
 538          */
 539         public function getUserText( $audience = self::FOR_PUBLIC, User $user = null ) {
 540                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_USER ) ) {
 541                         return '';
 542                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_USER, $user ) ) {
 543                         return '';
 544                 } else {
 545                         return $this->mUserText;
 546                 }
 547         }
 548
 549         /**
 550          * Fetch revision's username without regard for view restrictions
 551          *
 552          * @return String
 553          */
 554         public function getRawUserText() {
 555                 return $this->mUserText;
 556         }
 557
 558         /**
 559          * Fetch revision comment if it's available to the specified audience.
 560          * If the specified audience does not have access to the comment, an
 561          * empty string will be returned.
 562          *
 563          * @param $audience Integer: one of:
 564          *      Revision::FOR_PUBLIC       to be displayed to all users
 565          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 566          *      Revision::RAW              get the text regardless of permissions
 567          * @param $user User object to check for, only if FOR_THIS_USER is passed
 568          *              to the $audience parameter
 569          * @return String
 570          */
 571         function getComment( $audience = self::FOR_PUBLIC, User $user = null ) {
 572                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_COMMENT ) ) {
 573                         return '';
 574                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_COMMENT, $user ) ) {
 575                         return '';
 576                 } else {
 577                         return $this->mComment;
 578                 }
 579         }
 580
 581         /**
 582          * Fetch revision comment without regard for the current user's permissions
 583          *
 584          * @return String
 585          */
 586         public function getRawComment() {
 587                 return $this->mComment;
 588         }
 589
 590         /**
 591          * @return Boolean
 592          */
 593         public function isMinor() {
 594                 return (bool)$this->mMinorEdit;
 595         }
 596
 597         /**
 598          * @return Integer rcid of the unpatrolled row, zero if there isn't one
 599          */
 600         public function isUnpatrolled() {
 601                 if( $this->mUnpatrolled !== null ) {
 602                         return $this->mUnpatrolled;
 603                 }
 604                 $dbr = wfGetDB( DB_SLAVE );
 605                 $this->mUnpatrolled = $dbr->selectField( 'recentchanges',
 606                         'rc_id',
 607                         array( // Add redundant user,timestamp condition so we can use the existing index
 608                                 'rc_user_text'  => $this->getRawUserText(),
 609                                 'rc_timestamp'  => $dbr->timestamp( $this->getTimestamp() ),
 610                                 'rc_this_oldid' => $this->getId(),
 611                                 'rc_patrolled'  => 0
 612                         ),
 613                         __METHOD__
 614                 );
 615                 return (int)$this->mUnpatrolled;
 616         }
 617
 618         /**
 619          * @param $field int one of DELETED_* bitfield constants
 620          *
 621          * @return Boolean
 622          */
 623         public function isDeleted( $field ) {
 624                 return ( $this->mDeleted & $field ) == $field;
 625         }
 626
 627         /**
 628          * Get the deletion bitfield of the revision
 629          *
 630          * @return int
 631          */
 632         public function getVisibility() {
 633                 return (int)$this->mDeleted;
 634         }
 635
 636         /**
 637          * Fetch revision text if it's available to the specified audience.
 638          * If the specified audience does not have the ability to view this
 639          * revision, an empty string will be returned.
 640          *
 641          * @param $audience Integer: one of:
 642          *      Revision::FOR_PUBLIC       to be displayed to all users
 643          *      Revision::FOR_THIS_USER    to be displayed to $wgUser
 644          *      Revision::RAW              get the text regardless of permissions
 645          * @param $user User object to check for, only if FOR_THIS_USER is passed
 646          *              to the $audience parameter
 647          * @return String
 648          */
 649         public function getText( $audience = self::FOR_PUBLIC, User $user = null ) {
 650                 if( $audience == self::FOR_PUBLIC && $this->isDeleted( self::DELETED_TEXT ) ) {
 651                         return '';
 652                 } elseif( $audience == self::FOR_THIS_USER && !$this->userCan( self::DELETED_TEXT, $user ) ) {
 653                         return '';
 654                 } else {
 655                         return $this->getRawText();
 656                 }
 657         }
 658
 659         /**
 660          * Alias for getText(Revision::FOR_THIS_USER)
 661          *
 662          * @deprecated since 1.17
 663          * @return String
 664          */
 665         public function revText() {
 666                 wfDeprecated( __METHOD__ );
 667                 return $this->getText( self::FOR_THIS_USER );
 668         }
 669
 670         /**
 671          * Fetch revision text without regard for view restrictions
 672          *
 673          * @return String
 674          */
 675         public function getRawText() {
 676                 if( is_null( $this->mText ) ) {
 677                         // Revision text is immutable. Load on demand:
 678                         $this->mText = $this->loadText();
 679                 }
 680                 return $this->mText;
 681         }
 682
 683         /**
 684          * @return String
 685          */
 686         public function getTimestamp() {
 687                 return wfTimestamp( TS_MW, $this->mTimestamp );
 688         }
 689
 690         /**
 691          * @return Boolean
 692          */
 693         public function isCurrent() {
 694                 return $this->mCurrent;
 695         }
 696
 697         /**
 698          * Get previous revision for this title
 699          *
 700          * @return Revision or null
 701          */
 702         public function getPrevious() {
 703                 if( $this->getTitle() ) {
 704                         $prev = $this->getTitle()->getPreviousRevisionID( $this->getId() );
 705                         if( $prev ) {
 706                                 return Revision::newFromTitle( $this->getTitle(), $prev );
 707                         }
 708                 }
 709                 return null;
 710         }
 711
 712         /**
 713          * Get next revision for this title
 714          *
 715          * @return Revision or null
 716          */
 717         public function getNext() {
 718                 if( $this->getTitle() ) {
 719                         $next = $this->getTitle()->getNextRevisionID( $this->getId() );
 720                         if ( $next ) {
 721                                 return Revision::newFromTitle( $this->getTitle(), $next );
 722                         }
 723                 }
 724                 return null;
 725         }
 726
 727         /**
 728          * Get previous revision Id for this page_id
 729          * This is used to populate rev_parent_id on save
 730          *
 731          * @param $db DatabaseBase
 732          * @return Integer
 733          */
 734         private function getPreviousRevisionId( $db ) {
 735                 if( is_null( $this->mPage ) ) {
 736                         return 0;
 737                 }
 738                 # Use page_latest if ID is not given
 739                 if( !$this->mId ) {
 740                         $prevId = $db->selectField( 'page', 'page_latest',
 741                                 array( 'page_id' => $this->mPage ),
 742                                 __METHOD__ );
 743                 } else {
 744                         $prevId = $db->selectField( 'revision', 'rev_id',
 745                                 array( 'rev_page' => $this->mPage, 'rev_id < ' . $this->mId ),
 746                                 __METHOD__,
 747                                 array( 'ORDER BY' => 'rev_id DESC' ) );
 748                 }
 749                 return intval( $prevId );
 750         }
 751
 752         /**
 753           * Get revision text associated with an old or archive row
 754           * $row is usually an object from wfFetchRow(), both the flags and the text
 755           * field must be included
 756           *
 757           * @param $row Object: the text data
 758           * @param $prefix String: table prefix (default 'old_')
 759           * @return String: text the text requested or false on failure
 760           */
 761         public static function getRevisionText( $row, $prefix = 'old_' ) {
 762                 wfProfileIn( __METHOD__ );
 763
 764                 # Get data
 765                 $textField = $prefix . 'text';
 766                 $flagsField = $prefix . 'flags';
 767
 768                 if( isset( $row->$flagsField ) ) {
 769                         $flags = explode( ',', $row->$flagsField );
 770                 } else {
 771                         $flags = array();
 772                 }
 773
 774                 if( isset( $row->$textField ) ) {
 775                         $text = $row->$textField;
 776                 } else {
 777                         wfProfileOut( __METHOD__ );
 778                         return false;
 779                 }
 780
 781                 # Use external methods for external objects, text in table is URL-only then
 782                 if ( in_array( 'external', $flags ) ) {
 783                         $url = $text;
 784                         $parts = explode( '://', $url, 2 );
 785                         if( count( $parts ) == 1 || $parts[1] == '' ) {
 786                                 wfProfileOut( __METHOD__ );
 787                                 return false;
 788                         }
 789                         $text = ExternalStore::fetchFromURL( $url );
 790                 }
 791
 792                 // If the text was fetched without an error, convert it
 793                 if ( $text !== false ) {
 794                         if( in_array( 'gzip', $flags ) ) {
 795                                 # Deal with optional compression of archived pages.
 796                                 # This can be done periodically via maintenance/compressOld.php, and
 797                                 # as pages are saved if $wgCompressRevisions is set.
 798                                 $text = gzinflate( $text );
 799                         }
 800
 801                         if( in_array( 'object', $flags ) ) {
 802                                 # Generic compressed storage
 803                                 $obj = unserialize( $text );
 804                                 if ( !is_object( $obj ) ) {
 805                                         // Invalid object
 806                                         wfProfileOut( __METHOD__ );
 807                                         return false;
 808                                 }
 809                                 $text = $obj->getText();
 810                         }
 811
 812                         global $wgLegacyEncoding;
 813                         if( $text !== false && $wgLegacyEncoding
 814                                 && !in_array( 'utf-8', $flags ) && !in_array( 'utf8', $flags ) )
 815                         {
 816                                 # Old revisions kept around in a legacy encoding?
 817                                 # Upconvert on demand.
 818                                 # ("utf8" checked for compatibility with some broken
 819                                 #  conversion scripts 2008-12-30)
 820                                 global $wgContLang;
 821                                 $text = $wgContLang->iconv( $wgLegacyEncoding, 'UTF-8', $text );
 822                         }
 823                 }
 824                 wfProfileOut( __METHOD__ );
 825                 return $text;
 826         }
 827
 828         /**
 829          * If $wgCompressRevisions is enabled, we will compress data.
 830          * The input string is modified in place.
 831          * Return value is the flags field: contains 'gzip' if the
 832          * data is compressed, and 'utf-8' if we're saving in UTF-8
 833          * mode.
 834          *
 835          * @param $text Mixed: reference to a text
 836          * @return String
 837          */
 838         public static function compressRevisionText( &$text ) {
 839                 global $wgCompressRevisions;
 840                 $flags = array();
 841
 842                 # Revisions not marked this way will be converted
 843                 # on load if $wgLegacyCharset is set in the future.
 844                 $flags[] = 'utf-8';
 845
 846                 if( $wgCompressRevisions ) {
 847                         if( function_exists( 'gzdeflate' ) ) {
 848                                 $text = gzdeflate( $text );
 849                                 $flags[] = 'gzip';
 850                         } else {
 851                                 wfDebug( "Revision::compressRevisionText() -- no zlib support, not compressing\n" );
 852                         }
 853                 }
 854                 return implode( ',', $flags );
 855         }
 856
 857         /**
 858          * Insert a new revision into the database, returning the new revision ID
 859          * number on success and dies horribly on failure.
 860          *
 861          * @param $dbw DatabaseBase: (master connection)
 862          * @return Integer
 863          */
 864         public function insertOn( $dbw ) {
 865                 global $wgDefaultExternalStore;
 866
 867                 wfProfileIn( __METHOD__ );
 868
 869                 $data = $this->mText;
 870                 $flags = Revision::compressRevisionText( $data );
 871
 872                 # Write to external storage if required
 873                 if( $wgDefaultExternalStore ) {
 874                         // Store and get the URL
 875                         $data = ExternalStore::insertToDefault( $data );
 876                         if( !$data ) {
 877                                 throw new MWException( "Unable to store text to external storage" );
 878                         }
 879                         if( $flags ) {
 880                                 $flags .= ',';
 881                         }
 882                         $flags .= 'external';
 883                 }
 884
 885                 # Record the text (or external storage URL) to the text table
 886                 if( !isset( $this->mTextId ) ) {
 887                         $old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );
 888                         $dbw->insert( 'text',
 889                                 array(
 890                                         'old_id'    => $old_id,
 891                                         'old_text'  => $data,
 892                                         'old_flags' => $flags,
 893                                 ), __METHOD__
 894                         );
 895                         $this->mTextId = $dbw->insertId();
 896                 }
 897
 898                 if ( $this->mComment === null ) $this->mComment = "";
 899
 900                 # Record the edit in revisions
 901                 $rev_id = isset( $this->mId )
 902                         ? $this->mId
 903                         : $dbw->nextSequenceValue( 'revision_rev_id_seq' );
 904                 $dbw->insert( 'revision',
 905                         array(
 906                                 'rev_id'         => $rev_id,
 907                                 'rev_page'       => $this->mPage,
 908                                 'rev_text_id'    => $this->mTextId,
 909                                 'rev_comment'    => $this->mComment,
 910                                 'rev_minor_edit' => $this->mMinorEdit ? 1 : 0,
 911                                 'rev_user'       => $this->mUser,
 912                                 'rev_user_text'  => $this->mUserText,
 913                                 'rev_timestamp'  => $dbw->timestamp( $this->mTimestamp ),
 914                                 'rev_deleted'    => $this->mDeleted,
 915                                 'rev_len'        => $this->mSize,
 916                                 'rev_parent_id'  => is_null($this->mParentId) ?
 917                                         $this->getPreviousRevisionId( $dbw ) : $this->mParentId
 918                         ), __METHOD__
 919                 );
 920
 921                 $this->mId = !is_null( $rev_id ) ? $rev_id : $dbw->insertId();
 922
 923                 wfRunHooks( 'RevisionInsertComplete', array( &$this, $data, $flags ) );
 924
 925                 wfProfileOut( __METHOD__ );
 926                 return $this->mId;
 927         }
 928
 929         /**
 930          * Lazy-load the revision's text.
 931          * Currently hardcoded to the 'text' table storage engine.
 932          *
 933          * @return String
 934          */
 935         protected function loadText() {
 936                 wfProfileIn( __METHOD__ );
 937
 938                 // Caching may be beneficial for massive use of external storage
 939                 global $wgRevisionCacheExpiry, $wgMemc;
 940                 $textId = $this->getTextId();
 941                 $key = wfMemcKey( 'revisiontext', 'textid', $textId );
 942                 if( $wgRevisionCacheExpiry ) {
 943                         $text = $wgMemc->get( $key );
 944                         if( is_string( $text ) ) {
 945                                 wfDebug( __METHOD__ . ": got id $textId from cache\n" );
 946                                 wfProfileOut( __METHOD__ );
 947                                 return $text;
 948                         }
 949                 }
 950
 951                 // If we kept data for lazy extraction, use it now...
 952                 if ( isset( $this->mTextRow ) ) {
 953                         $row = $this->mTextRow;
 954                         $this->mTextRow = null;
 955                 } else {
 956                         $row = null;
 957                 }
 958
 959                 if( !$row ) {
 960                         // Text data is immutable; check slaves first.
 961                         $dbr = wfGetDB( DB_SLAVE );
 962                         $row = $dbr->selectRow( 'text',
 963                                 array( 'old_text', 'old_flags' ),
 964                                 array( 'old_id' => $this->getTextId() ),
 965                                 __METHOD__ );
 966                 }
 967
 968                 if( !$row && wfGetLB()->getServerCount() > 1 ) {
 969                         // Possible slave lag!
 970                         $dbw = wfGetDB( DB_MASTER );
 971                         $row = $dbw->selectRow( 'text',
 972                                 array( 'old_text', 'old_flags' ),
 973                                 array( 'old_id' => $this->getTextId() ),
 974                                 __METHOD__ );
 975                 }
 976
 977                 $text = self::getRevisionText( $row );
 978
 979                 # No negative caching -- negative hits on text rows may be due to corrupted slave servers
 980                 if( $wgRevisionCacheExpiry && $text !== false ) {
 981                         $wgMemc->set( $key, $text, $wgRevisionCacheExpiry );
 982                 }
 983
 984                 wfProfileOut( __METHOD__ );
 985
 986                 return $text;
 987         }
 988
 989         /**
 990          * Create a new null-revision for insertion into a page's
 991          * history. This will not re-save the text, but simply refer
 992          * to the text from the previous version.
 993          *
 994          * Such revisions can for instance identify page rename
 995          * operations and other such meta-modifications.
 996          *
 997          * @param $dbw DatabaseBase
 998          * @param $pageId Integer: ID number of the page to read from
 999          * @param $summary String: revision's summary
1000          * @param $minor Boolean: whether the revision should be considered as minor
1001          * @return Revision|null on error
1002          */
1003         public static function newNullRevision( $dbw, $pageId, $summary, $minor ) {
1004                 wfProfileIn( __METHOD__ );
1005
1006                 $current = $dbw->selectRow(
1007                         array( 'page', 'revision' ),
1008                         array( 'page_latest', 'rev_text_id', 'rev_len' ),
1009                         array(
1010                                 'page_id' => $pageId,
1011                                 'page_latest=rev_id',
1012                                 ),
1013                         __METHOD__ );
1014
1015                 if( $current ) {
1016                         $revision = new Revision( array(
1017                                 'page'       => $pageId,
1018                                 'comment'    => $summary,
1019                                 'minor_edit' => $minor,
1020                                 'text_id'    => $current->rev_text_id,
1021                                 'parent_id'  => $current->page_latest,
1022                                 'len'        => $current->rev_len
1023                                 ) );
1024                 } else {
1025                         $revision = null;
1026                 }
1027
1028                 wfProfileOut( __METHOD__ );
1029                 return $revision;
1030         }
1031
1032         /**
1033          * Determine if the current user is allowed to view a particular
1034          * field of this revision, if it's marked as deleted.
1035          *
1036          * @param $field Integer:one of self::DELETED_TEXT,
1037          *                              self::DELETED_COMMENT,
1038          *                              self::DELETED_USER
1039          * @param $user User object to check, or null to use $wgUser
1040          * @return Boolean
1041          */
1042         public function userCan( $field, User $user = null ) {
1043                 return self::userCanBitfield( $this->mDeleted, $field, $user );
1044         }
1045
1046         /**
1047          * Determine if the current user is allowed to view a particular
1048          * field of this revision, if it's marked as deleted. This is used
1049          * by various classes to avoid duplication.
1050          *
1051          * @param $bitfield Integer: current field
1052          * @param $field Integer: one of self::DELETED_TEXT = File::DELETED_FILE,
1053          *                               self::DELETED_COMMENT = File::DELETED_COMMENT,
1054          *                               self::DELETED_USER = File::DELETED_USER
1055          * @param $user User object to check, or null to use $wgUser
1056          * @return Boolean
1057          */
1058         public static function userCanBitfield( $bitfield, $field, User $user = null ) {
1059                 if( $bitfield & $field ) { // aspect is deleted
1060                         if ( $bitfield & self::DELETED_RESTRICTED ) {
1061                                 $permission = 'suppressrevision';
1062                         } elseif ( $field & self::DELETED_TEXT ) {
1063                                 $permission = 'deletedtext';
1064                         } else {
1065                                 $permission = 'deletedhistory';
1066                         }
1067                         wfDebug( "Checking for $permission due to $field match on $bitfield\n" );
1068                         if ( $user === null ) {
1069                                 global $wgUser;
1070                                 $user = $wgUser;
1071                         }
1072                         return $user->isAllowed( $permission );
1073                 } else {
1074                         return true;
1075                 }
1076         }
1077
1078         /**
1079          * Get rev_timestamp from rev_id, without loading the rest of the row
1080          *
1081          * @param $title Title
1082          * @param $id Integer
1083          * @return String
1084          */
1085         static function getTimestampFromId( $title, $id ) {
1086                 $dbr = wfGetDB( DB_SLAVE );
1087                 // Casting fix for DB2
1088                 if ( $id == '' ) {
1089                         $id = 0;
1090                 }
1091                 $conds = array( 'rev_id' => $id );
1092                 $conds['rev_page'] = $title->getArticleId();
1093                 $timestamp = $dbr->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1094                 if ( $timestamp === false && wfGetLB()->getServerCount() > 1 ) {
1095                         # Not in slave, try master
1096                         $dbw = wfGetDB( DB_MASTER );
1097                         $timestamp = $dbw->selectField( 'revision', 'rev_timestamp', $conds, __METHOD__ );
1098                 }
1099                 return wfTimestamp( TS_MW, $timestamp );
1100         }
1101
1102         /**
1103          * Get count of revisions per page...not very efficient
1104          *
1105          * @param $db DatabaseBase
1106          * @param $id Integer: page id
1107          * @return Integer
1108          */
1109         static function countByPageId( $db, $id ) {
1110                 $row = $db->selectRow( 'revision', 'COUNT(*) AS revCount',
1111                         array( 'rev_page' => $id ), __METHOD__ );
1112                 if( $row ) {
1113                         return $row->revCount;
1114                 }
1115                 return 0;
1116         }
1117
1118         /**
1119          * Get count of revisions per page...not very efficient
1120          *
1121          * @param $db DatabaseBase
1122          * @param $title Title
1123          * @return Integer
1124          */
1125         static function countByTitle( $db, $title ) {
1126                 $id = $title->getArticleId();
1127                 if( $id ) {
1128                         return Revision::countByPageId( $db, $id );
1129                 }
1130                 return 0;
1131         }
1132 }