includes/diff/DifferenceEngine.php

   1 <?php
   2 /**
   3  * User interface for the difference engine.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup DifferenceEngine
  22  */
  23
  24 /**
  25  * Constant to indicate diff cache compatibility.
  26  * Bump this when changing the diff formatting in a way that
  27  * fixes important bugs or such to force cached diff views to
  28  * clear.
  29  */
  30 define( 'MW_DIFF_VERSION', '1.11a' );
  31
  32 /**
  33  * @todo document
  34  * @ingroup DifferenceEngine
  35  */
  36 class DifferenceEngine extends ContextSource {
  37         /**#@+
  38          * @private
  39          */
  40         var $mOldid, $mNewid;
  41         var $mOldtext, $mNewtext;
  42         protected $mDiffLang;
  43
  44         /**
  45          * @var Title
  46          */
  47         var $mOldPage, $mNewPage;
  48         var $mRcidMarkPatrolled;
  49
  50         /**
  51          * @var Revision
  52          */
  53         var $mOldRev, $mNewRev;
  54         private $mRevisionsIdsLoaded = false; // Have the revisions IDs been loaded
  55         var $mRevisionsLoaded = false; // Have the revisions been loaded
  56         var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
  57         var $mCacheHit = false; // Was the diff fetched from cache?
  58
  59         /**
  60          * Set this to true to add debug info to the HTML output.
  61          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  62          * (bug 20601)
  63          */
  64         var $enableDebugComment = false;
  65
  66         // If true, line X is not displayed when X is 1, for example to increase
  67         // readability and conserve space with many small diffs.
  68         protected $mReducedLineNumbers = false;
  69
  70         // Link to action=markpatrolled
  71         protected $mMarkPatrolledLink = null;
  72
  73         protected $unhide = false; # show rev_deleted content if allowed
  74         /**#@-*/
  75
  76         /**
  77          * Constructor
  78          * @param $context IContextSource context to use, anything else will be ignored
  79          * @param $old Integer old ID we want to show and diff with.
  80          * @param $new String either 'prev' or 'next'.
  81          * @param $rcid Integer ??? FIXME (default 0)
  82          * @param $refreshCache boolean If set, refreshes the diff cache
  83          * @param $unhide boolean If set, allow viewing deleted revs
  84          */
  85         function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
  86                 $refreshCache = false, $unhide = false )
  87         {
  88                 if ( $context instanceof IContextSource ) {
  89                         $this->setContext( $context );
  90                 }
  91
  92                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
  93
  94                 $this->mOldid = $old;
  95                 $this->mNewid = $new;
  96                 $this->mRcidMarkPatrolled = intval( $rcid );  # force it to be an integer
  97                 $this->mRefreshCache = $refreshCache;
  98                 $this->unhide = $unhide;
  99         }
 100
 101         /**
 102          * @param $value bool
 103          */
 104         function setReducedLineNumbers( $value = true ) {
 105                 $this->mReducedLineNumbers = $value;
 106         }
 107
 108         /**
 109          * @return Language
 110          */
 111         function getDiffLang() {
 112                 if ( $this->mDiffLang === null ) {
 113                         # Default language in which the diff text is written.
 114                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 115                 }
 116                 return $this->mDiffLang;
 117         }
 118
 119         /**
 120          * @return bool
 121          */
 122         function wasCacheHit() {
 123                 return $this->mCacheHit;
 124         }
 125
 126         /**
 127          * @return int
 128          */
 129         function getOldid() {
 130                 $this->loadRevisionIds();
 131                 return $this->mOldid;
 132         }
 133
 134         /**
 135          * @return Bool|int
 136          */
 137         function getNewid() {
 138                 $this->loadRevisionIds();
 139                 return $this->mNewid;
 140         }
 141
 142         /**
 143          * Look up a special:Undelete link to the given deleted revision id,
 144          * as a workaround for being unable to load deleted diffs in currently.
 145          *
 146          * @param int $id revision ID
 147          * @return mixed URL or false
 148          */
 149         function deletedLink( $id ) {
 150                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 151                         $dbr = wfGetDB( DB_SLAVE );
 152                         $row = $dbr->selectRow('archive', '*',
 153                                 array( 'ar_rev_id' => $id ),
 154                                 __METHOD__ );
 155                         if ( $row ) {
 156                                 $rev = Revision::newFromArchiveRow( $row );
 157                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 158                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( array(
 159                                         'target' => $title->getPrefixedText(),
 160                                         'timestamp' => $rev->getTimestamp()
 161                                 ));
 162                         }
 163                 }
 164                 return false;
 165         }
 166
 167         /**
 168          * Build a wikitext link toward a deleted revision, if viewable.
 169          *
 170          * @param int $id revision ID
 171          * @return string wikitext fragment
 172          */
 173         function deletedIdMarker( $id ) {
 174                 $link = $this->deletedLink( $id );
 175                 if ( $link ) {
 176                         return "[$link $id]";
 177                 } else {
 178                         return $id;
 179                 }
 180         }
 181
 182         function showDiffPage( $diffOnly = false ) {
 183                 wfProfileIn( __METHOD__ );
 184
 185                 # Allow frames except in certain special cases
 186                 $out = $this->getOutput();
 187                 $out->allowClickjacking();
 188                 $out->setRobotPolicy( 'noindex,nofollow' );
 189
 190                 if ( !$this->loadRevisionData() ) {
 191                         // Sounds like a deleted revision... Let's see what we can do.
 192                         $t = $this->getTitle()->getPrefixedText();
 193                         $d = $this->msg( 'missingarticle-diff',
 194                                 $this->deletedIdMarker( $this->mOldid ),
 195                                 $this->deletedIdMarker( $this->mNewid ) )->escaped();
 196                         $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 197                         $out->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", "<span class='plainlinks'>$d</span>" );
 198                         wfProfileOut( __METHOD__ );
 199                         return;
 200                 }
 201
 202                 $user = $this->getUser();
 203                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 204                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 205                         $permErrors = wfMergeErrorArrays( $permErrors,
 206                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 207                 }
 208                 if ( count( $permErrors ) ) {
 209                         wfProfileOut( __METHOD__ );
 210                         throw new PermissionsError( 'read', $permErrors );
 211                 }
 212
 213                 # If external diffs are enabled both globally and for the user,
 214                 # we'll use the application/x-external-editor interface to call
 215                 # an external diff tool like kompare, kdiff3, etc.
 216                 if ( ExternalEdit::useExternalEngine( $this->getContext(), 'diff' ) ) {
 217                         $urls = array(
 218                                 'File' => array( 'Extension' => 'wiki', 'URL' =>
 219                                         # This should be mOldPage, but it may not be set, see below.
 220                                         $this->mNewPage->getCanonicalURL( array(
 221                                                 'action' => 'raw', 'oldid' => $this->mOldid ) )
 222                                 ),
 223                                 'File2' => array( 'Extension' => 'wiki', 'URL' =>
 224                                         $this->mNewPage->getCanonicalURL( array(
 225                                                 'action' => 'raw', 'oldid' => $this->mNewid ) )
 226                                 ),
 227                         );
 228
 229                         $externalEditor = new ExternalEdit( $this->getContext(), $urls );
 230                         $externalEditor->execute();
 231
 232                         wfProfileOut( __METHOD__ );
 233                         return;
 234                 }
 235
 236                 $rollback = '';
 237                 $undoLink = '';
 238
 239                 $query = array();
 240                 # Carry over 'diffonly' param via navigation links
 241                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 242                         $query['diffonly'] = $diffOnly;
 243                 }
 244                 # Cascade unhide param in links for easy deletion browsing
 245                 if ( $this->unhide ) {
 246                         $query['unhide'] = 1;
 247                 }
 248
 249                 # Check if one of the revisions is deleted/suppressed
 250                 $deleted = $suppressed = false;
 251                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 252
 253                 # mOldRev is false if the difference engine is called with a "vague" query for
 254                 # a diff between a version V and its previous version V' AND the version V
 255                 # is the first version of that article. In that case, V' does not exist.
 256                 if ( $this->mOldRev === false ) {
 257                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 258                         $samePage = true;
 259                         $oldHeader = '';
 260                 } else {
 261                         wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 262
 263                         $sk = $this->getSkin();
 264                         if ( method_exists( $sk, 'suppressQuickbar' ) ) {
 265                                 $sk->suppressQuickbar();
 266                         }
 267
 268                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 269                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 270                                 $samePage = true;
 271                         } else {
 272                                 $out->setPageTitle( $this->msg( 'difference-title-multipage', $this->mOldPage->getPrefixedText(),
 273                                         $this->mNewPage->getPrefixedText() ) );
 274                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 275                                 $samePage = false;
 276                         }
 277
 278                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 279                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 280                                         $out->preventClickjacking();
 281                                         $rollback = '&#160;&#160;&#160;' . Linker::generateRollback( $this->mNewRev );
 282                                 }
 283                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 284                                         $undoLink = ' ' . $this->msg( 'parentheses' )->rawParams(
 285                                                 Html::element( 'a', array(
 286                                                         'href' => $this->mNewPage->getLocalUrl( array(
 287                                                                 'action' => 'edit',
 288                                                                 'undoafter' => $this->mOldid,
 289                                                                 'undo' => $this->mNewid ) ),
 290                                                         'title' => Linker::titleAttrib( 'undo' )
 291                                                 ),
 292                                                 $this->msg( 'editundo' )->text()
 293                                         ) )->escaped();
 294                                 }
 295                         }
 296
 297                         # Make "previous revision link"
 298                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 299                                 $prevlink = Linker::linkKnown(
 300                                         $this->mOldPage,
 301                                         $this->msg( 'previousdiff' )->escaped(),
 302                                         array( 'id' => 'differences-prevlink' ),
 303                                         array( 'diff' => 'prev', 'oldid' => $this->mOldid ) + $query
 304                                 );
 305                         } else {
 306                                 $prevlink = '&#160;';
 307                         }
 308
 309                         if ( $this->mOldRev->isMinor() ) {
 310                                 $oldminor = ChangesList::flag( 'minor' );
 311                         } else {
 312                                 $oldminor = '';
 313                         }
 314
 315                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 316                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 317
 318                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 319                                 '<div id="mw-diff-otitle2">' .
 320                                         Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 321                                 '<div id="mw-diff-otitle3">' . $oldminor .
 322                                         Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 323                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 324
 325                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 326                                 $deleted = true; // old revisions text is hidden
 327                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 328                                         $suppressed = true; // also suppressed
 329                                 }
 330                         }
 331
 332                         # Check if this user can see the revisions
 333                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 334                                 $allowed = false;
 335                         }
 336                 }
 337
 338                 # Make "next revision link"
 339                 # Skip next link on the top revision
 340                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 341                         $nextlink = Linker::linkKnown(
 342                                 $this->mNewPage,
 343                                 $this->msg( 'nextdiff' )->escaped(),
 344                                 array( 'id' => 'differences-nextlink' ),
 345                                 array( 'diff' => 'next', 'oldid' => $this->mNewid ) + $query
 346                         );
 347                 } else {
 348                         $nextlink = '&#160;';
 349                 }
 350
 351                 if ( $this->mNewRev->isMinor() ) {
 352                         $newminor = ChangesList::flag( 'minor' );
 353                 } else {
 354                         $newminor = '';
 355                 }
 356
 357                 # Handle RevisionDelete links...
 358                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 359                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) . $undoLink;
 360
 361                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 362                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 363                                 " $rollback</div>" .
 364                         '<div id="mw-diff-ntitle3">' . $newminor .
 365                                 Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 366                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 367
 368                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 369                         $deleted = true; // new revisions text is hidden
 370                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) )
 371                                 $suppressed = true; // also suppressed
 372                 }
 373
 374                 # If the diff cannot be shown due to a deleted revision, then output
 375                 # the diff header and links to unhide (if available)...
 376                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 377                         $this->showDiffStyle();
 378                         $multi = $this->getMultiNotice();
 379                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 380                         if ( !$allowed ) {
 381                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 382                                 # Give explanation for why revision is not visible
 383                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 384                                         array( $msg ) );
 385                         } else {
 386                                 # Give explanation and add a link to view the diff...
 387                                 $link = $this->getTitle()->getFullUrl( $this->getRequest()->appendQueryValue( 'unhide', '1', true ) );
 388                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 389                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n", array( $msg, $link ) );
 390                         }
 391                 # Otherwise, output a regular diff...
 392                 } else {
 393                         # Add deletion notice if the user is viewing deleted content
 394                         $notice = '';
 395                         if ( $deleted ) {
 396                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 397                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" . $this->msg( $msg )->parse() . "</div>\n";
 398                         }
 399                         $this->showDiff( $oldHeader, $newHeader, $notice );
 400                         if ( !$diffOnly ) {
 401                                 $this->renderNewRevision();
 402                         }
 403                 }
 404                 wfProfileOut( __METHOD__ );
 405         }
 406
 407         /**
 408          * Get a link to mark the change as patrolled, or '' if there's either no
 409          * revision to patrol or the user is not allowed to to it.
 410          * Side effect: this method will call OutputPage::preventClickjacking()
 411          * when a link is builded.
 412          *
 413          * @return String
 414          */
 415         protected function markPatrolledLink() {
 416                 global $wgUseRCPatrol;
 417
 418                 if ( $this->mMarkPatrolledLink === null ) {
 419                         // Prepare a change patrol link, if applicable
 420                         if ( $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $this->getUser() ) ) {
 421                                 // If we've been given an explicit change identifier, use it; saves time
 422                                 if ( $this->mRcidMarkPatrolled ) {
 423                                         $rcid = $this->mRcidMarkPatrolled;
 424                                         $rc = RecentChange::newFromId( $rcid );
 425                                         // Already patrolled?
 426                                         $rcid = is_object( $rc ) && !$rc->getAttribute( 'rc_patrolled' ) ? $rcid : 0;
 427                                 } else {
 428                                         // Look for an unpatrolled change corresponding to this diff
 429                                         $db = wfGetDB( DB_SLAVE );
 430                                         $change = RecentChange::newFromConds(
 431                                                 array(
 432                                                 // Redundant user,timestamp condition so we can use the existing index
 433                                                         'rc_user_text'  => $this->mNewRev->getRawUserText(),
 434                                                         'rc_timestamp'  => $db->timestamp( $this->mNewRev->getTimestamp() ),
 435                                                         'rc_this_oldid' => $this->mNewid,
 436                                                         'rc_last_oldid' => $this->mOldid,
 437                                                         'rc_patrolled'  => 0
 438                                                 ),
 439                                                 __METHOD__
 440                                         );
 441                                         if ( $change instanceof RecentChange ) {
 442                                                 $rcid = $change->mAttribs['rc_id'];
 443                                                 $this->mRcidMarkPatrolled = $rcid;
 444                                         } else {
 445                                                 // None found
 446                                                 $rcid = 0;
 447                                         }
 448                                 }
 449                                 // Build the link
 450                                 if ( $rcid ) {
 451                                         $this->getOutput()->preventClickjacking();
 452                                         $token = $this->getUser()->getEditToken( $rcid );
 453                                         $this->mMarkPatrolledLink = ' <span class="patrollink">[' . Linker::linkKnown(
 454                                                 $this->mNewPage,
 455                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 456                                                 array(),
 457                                                 array(
 458                                                         'action' => 'markpatrolled',
 459                                                         'rcid' => $rcid,
 460                                                         'token' => $token,
 461                                                 )
 462                                         ) . ']</span>';
 463                                 } else {
 464                                         $this->mMarkPatrolledLink = '';
 465                                 }
 466                         } else {
 467                                 $this->mMarkPatrolledLink = '';
 468                         }
 469                 }
 470
 471                 return $this->mMarkPatrolledLink;
 472         }
 473
 474         /**
 475          * @param $rev Revision
 476          * @return String
 477          */
 478         protected function revisionDeleteLink( $rev ) {
 479                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 480                 if ( $link !== '' ) {
 481                         $link = '&#160;&#160;&#160;' . $link . ' ';
 482                 }
 483                 return $link;
 484         }
 485
 486         /**
 487          * Show the new revision of the page.
 488          */
 489         function renderNewRevision() {
 490                 wfProfileIn( __METHOD__ );
 491                 $out = $this->getOutput();
 492                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 493                 # Add "current version as of X" title
 494                 $out->addHTML( "<hr class='diff-hr' />
 495                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 496                 # Page content may be handled by a hooked call instead...
 497                 if ( wfRunHooks( 'ArticleContentOnDiff', array( $this, $out ) ) ) {
 498                         $this->loadNewText();
 499                         $out->setRevisionId( $this->mNewid );
 500                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 501                         $out->setArticleFlag( true );
 502
 503                         if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
 504                                 // Stolen from Article::view --AG 2007-10-11
 505                                 // Give hooks a chance to customise the output
 506                                 // @TODO: standardize this crap into one function
 507                                 if ( wfRunHooks( 'ShowRawCssJs', array( $this->mNewtext, $this->mNewPage, $out ) ) ) {
 508                                         // Wrap the whole lot in a <pre> and don't parse
 509                                         $m = array();
 510                                         preg_match( '!\.(css|js)$!u', $this->mNewPage->getText(), $m );
 511                                         $out->addHTML( "<pre class=\"mw-code mw-{$m[1]}\" dir=\"ltr\">\n" );
 512                                         $out->addHTML( htmlspecialchars( $this->mNewtext ) );
 513                                         $out->addHTML( "\n</pre>\n" );
 514                                 }
 515                         } elseif ( !wfRunHooks( 'ArticleViewCustom', array( $this->mNewtext, $this->mNewPage, $out ) ) ) {
 516                                 // Handled by extension
 517                         } else {
 518                                 // Normal page
 519                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 520                                         // If the Title stored in the context is the same as the one
 521                                         // of the new revision, we can use its associated WikiPage
 522                                         // object.
 523                                         $wikiPage = $this->getWikiPage();
 524                                 } else {
 525                                         // Otherwise we need to create our own WikiPage object
 526                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 527                                 }
 528
 529                                 $parserOptions = ParserOptions::newFromContext( $this->getContext() );
 530                                 $parserOptions->enableLimitReport();
 531                                 $parserOptions->setTidy( true );
 532
 533                                 if ( !$this->mNewRev->isCurrent() ) {
 534                                         $parserOptions->setEditSection( false );
 535                                 }
 536
 537                                 $parserOutput = $wikiPage->getParserOutput( $parserOptions, $this->mNewid );
 538
 539                                 # WikiPage::getParserOutput() should not return false, but just in case
 540                                 if( $parserOutput ) {
 541                                         $out->addParserOutput( $parserOutput );
 542                                 }
 543                         }
 544                 }
 545                 # Add redundant patrol link on bottom...
 546                 $out->addHTML( $this->markPatrolledLink() );
 547
 548                 wfProfileOut( __METHOD__ );
 549         }
 550
 551         /**
 552          * Get the diff text, send it to the OutputPage object
 553          * Returns false if the diff could not be generated, otherwise returns true
 554          *
 555          * @return bool
 556          */
 557         function showDiff( $otitle, $ntitle, $notice = '' ) {
 558                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 559                 if ( $diff === false ) {
 560                         $this->getOutput()->addWikiMsg( 'missing-article', "<nowiki>(fixme, bug)</nowiki>", '' );
 561                         return false;
 562                 } else {
 563                         $this->showDiffStyle();
 564                         $this->getOutput()->addHTML( $diff );
 565                         return true;
 566                 }
 567         }
 568
 569         /**
 570          * Add style sheets and supporting JS for diff display.
 571          */
 572         function showDiffStyle() {
 573                 $this->getOutput()->addModuleStyles( 'mediawiki.action.history.diff' );
 574         }
 575
 576         /**
 577          * Get complete diff table, including header
 578          *
 579          * @param $otitle Title: old title
 580          * @param $ntitle Title: new title
 581          * @param $notice String: HTML between diff header and body
 582          * @return mixed
 583          */
 584         function getDiff( $otitle, $ntitle, $notice = '' ) {
 585                 $body = $this->getDiffBody();
 586                 if ( $body === false ) {
 587                         return false;
 588                 } else {
 589                         $multi = $this->getMultiNotice();
 590                         return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 591                 }
 592         }
 593
 594         /**
 595          * Get the diff table body, without header
 596          *
 597          * @return mixed (string/false)
 598          */
 599         public function getDiffBody() {
 600                 global $wgMemc;
 601                 wfProfileIn( __METHOD__ );
 602                 $this->mCacheHit = true;
 603                 // Check if the diff should be hidden from this user
 604                 if ( !$this->loadRevisionData() ) {
 605                         wfProfileOut( __METHOD__ );
 606                         return false;
 607                 } elseif ( $this->mOldRev && !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 608                         wfProfileOut( __METHOD__ );
 609                         return false;
 610                 } elseif ( $this->mNewRev && !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 611                         wfProfileOut( __METHOD__ );
 612                         return false;
 613                 }
 614                 // Short-circuit
 615                 // If mOldRev is false, it means that the
 616                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 617                         && $this->mOldRev->getID() == $this->mNewRev->getID() ) )
 618                 {
 619                         wfProfileOut( __METHOD__ );
 620                         return '';
 621                 }
 622                 // Cacheable?
 623                 $key = false;
 624                 if ( $this->mOldid && $this->mNewid ) {
 625                         $key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION,
 626                                 'oldid', $this->mOldid, 'newid', $this->mNewid );
 627                         // Try cache
 628                         if ( !$this->mRefreshCache ) {
 629                                 $difftext = $wgMemc->get( $key );
 630                                 if ( $difftext ) {
 631                                         wfIncrStats( 'diff_cache_hit' );
 632                                         $difftext = $this->localiseLineNumbers( $difftext );
 633                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 634                                         wfProfileOut( __METHOD__ );
 635                                         return $difftext;
 636                                 }
 637                         } // don't try to load but save the result
 638                 }
 639                 $this->mCacheHit = false;
 640
 641                 // Loadtext is permission safe, this just clears out the diff
 642                 if ( !$this->loadText() ) {
 643                         wfProfileOut( __METHOD__ );
 644                         return false;
 645                 }
 646
 647                 $difftext = $this->generateDiffBody( $this->mOldtext, $this->mNewtext );
 648
 649                 // Save to cache for 7 days
 650                 if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
 651                         wfIncrStats( 'diff_uncacheable' );
 652                 } elseif ( $key !== false && $difftext !== false ) {
 653                         wfIncrStats( 'diff_cache_miss' );
 654                         $wgMemc->set( $key, $difftext, 7 * 86400 );
 655                 } else {
 656                         wfIncrStats( 'diff_uncacheable' );
 657                 }
 658                 // Replace line numbers with the text in the user's language
 659                 if ( $difftext !== false ) {
 660                         $difftext = $this->localiseLineNumbers( $difftext );
 661                 }
 662                 wfProfileOut( __METHOD__ );
 663                 return $difftext;
 664         }
 665
 666         /**
 667          * Make sure the proper modules are loaded before we try to
 668          * make the diff
 669          */
 670         private function initDiffEngines() {
 671                 global $wgExternalDiffEngine;
 672                 if ( $wgExternalDiffEngine == 'wikidiff' && !function_exists( 'wikidiff_do_diff' ) ) {
 673                         wfProfileIn( __METHOD__ . '-php_wikidiff.so' );
 674                         wfDl( 'php_wikidiff' );
 675                         wfProfileOut( __METHOD__ . '-php_wikidiff.so' );
 676                 }
 677                 elseif ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
 678                         wfProfileIn( __METHOD__ . '-php_wikidiff2.so' );
 679                         wfDl( 'wikidiff2' );
 680                         wfProfileOut( __METHOD__ . '-php_wikidiff2.so' );
 681                 }
 682         }
 683
 684         /**
 685          * Generate a diff, no caching
 686          *
 687          * @param $otext String: old text, must be already segmented
 688          * @param $ntext String: new text, must be already segmented
 689          * @return bool|string
 690          */
 691         function generateDiffBody( $otext, $ntext ) {
 692                 global $wgExternalDiffEngine, $wgContLang;
 693
 694                 wfProfileIn( __METHOD__ );
 695
 696                 $otext = str_replace( "\r\n", "\n", $otext );
 697                 $ntext = str_replace( "\r\n", "\n", $ntext );
 698
 699                 $this->initDiffEngines();
 700
 701                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 702                         # For historical reasons, external diff engine expects
 703                         # input text to be HTML-escaped already
 704                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 705                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 706                         wfProfileOut( __METHOD__ );
 707                         return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 708                         $this->debug( 'wikidiff1' );
 709                 }
 710
 711                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 712                         # Better external diff engine, the 2 may some day be dropped
 713                         # This one does the escaping and segmenting itself
 714                         wfProfileIn( 'wikidiff2_do_diff' );
 715                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 716                         $text .= $this->debug( 'wikidiff2' );
 717                         wfProfileOut( 'wikidiff2_do_diff' );
 718                         wfProfileOut( __METHOD__ );
 719                         return $text;
 720                 }
 721                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 722                         # Diff via the shell
 723                         global $wgTmpDirectory;
 724                         $tempName1 = tempnam( $wgTmpDirectory, 'diff_' );
 725                         $tempName2 = tempnam( $wgTmpDirectory, 'diff_' );
 726
 727                         $tempFile1 = fopen( $tempName1, "w" );
 728                         if ( !$tempFile1 ) {
 729                                 wfProfileOut( __METHOD__ );
 730                                 return false;
 731                         }
 732                         $tempFile2 = fopen( $tempName2, "w" );
 733                         if ( !$tempFile2 ) {
 734                                 wfProfileOut( __METHOD__ );
 735                                 return false;
 736                         }
 737                         fwrite( $tempFile1, $otext );
 738                         fwrite( $tempFile2, $ntext );
 739                         fclose( $tempFile1 );
 740                         fclose( $tempFile2 );
 741                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 742                         wfProfileIn( __METHOD__ . "-shellexec" );
 743                         $difftext = wfShellExec( $cmd );
 744                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 745                         wfProfileOut( __METHOD__ . "-shellexec" );
 746                         unlink( $tempName1 );
 747                         unlink( $tempName2 );
 748                         wfProfileOut( __METHOD__ );
 749                         return $difftext;
 750                 }
 751
 752                 # Native PHP diff
 753                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 754                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 755                 $diffs = new Diff( $ota, $nta );
 756                 $formatter = new TableDiffFormatter();
 757                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 758                 wfProfileOut( __METHOD__ );
 759                 return $difftext;
 760         }
 761
 762         /**
 763          * Generate a debug comment indicating diff generating time,
 764          * server node, and generator backend.
 765          * @return string
 766          */
 767         protected function debug( $generator = "internal" ) {
 768                 global $wgShowHostnames;
 769                 if ( !$this->enableDebugComment ) {
 770                         return '';
 771                 }
 772                 $data = array( $generator );
 773                 if ( $wgShowHostnames ) {
 774                         $data[] = wfHostname();
 775                 }
 776                 $data[] = wfTimestamp( TS_DB );
 777                 return "<!-- diff generator: " .
 778                 implode( " ",
 779                 array_map(
 780                                         "htmlspecialchars",
 781                 $data ) ) .
 782                         " -->\n";
 783         }
 784
 785         /**
 786          * Replace line numbers with the text in the user's language
 787          * @return mixed
 788          */
 789         function localiseLineNumbers( $text ) {
 790                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 791                 array( &$this, 'localiseLineNumbersCb' ), $text );
 792         }
 793
 794         function localiseLineNumbersCb( $matches ) {
 795                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) return '';
 796                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 797         }
 798
 799
 800         /**
 801          * If there are revisions between the ones being compared, return a note saying so.
 802          * @return string
 803          */
 804         function getMultiNotice() {
 805                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 806                         return '';
 807                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 808                         // Comparing two different pages? Count would be meaningless.
 809                         return '';
 810                 }
 811
 812                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 813                         $oldRev = $this->mNewRev; // flip
 814                         $newRev = $this->mOldRev; // flip
 815                 } else { // normal case
 816                         $oldRev = $this->mOldRev;
 817                         $newRev = $this->mNewRev;
 818                 }
 819
 820                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev );
 821                 if ( $nEdits > 0 ) {
 822                         $limit = 100; // use diff-multi-manyusers if too many users
 823                         $numUsers = $this->mNewPage->countAuthorsBetween( $oldRev, $newRev, $limit );
 824                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 825                 }
 826                 return ''; // nothing
 827         }
 828
 829         /**
 830          * Get a notice about how many intermediate edits and users there are
 831          * @param $numEdits int
 832          * @param $numUsers int
 833          * @param $limit int
 834          * @return string
 835          */
 836         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 837                 if ( $numUsers > $limit ) {
 838                         $msg = 'diff-multi-manyusers';
 839                         $numUsers = $limit;
 840                 } else {
 841                         $msg = 'diff-multi';
 842                 }
 843                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 844         }
 845
 846         /**
 847          * Get a header for a specified revision.
 848          *
 849          * @param $rev Revision
 850          * @param $complete String: 'complete' to get the header wrapped depending
 851          *        the visibility of the revision and a link to edit the page.
 852          * @return String HTML fragment
 853          */
 854         private function getRevisionHeader( Revision $rev, $complete = '' ) {
 855                 $lang = $this->getLanguage();
 856                 $user = $this->getUser();
 857                 $revtimestamp = $rev->getTimestamp();
 858                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
 859                 $dateofrev = $lang->userDate( $revtimestamp, $user );
 860                 $timeofrev = $lang->userTime( $revtimestamp, $user );
 861
 862                 $header = $this->msg(
 863                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
 864                         $timestamp,
 865                         $dateofrev,
 866                         $timeofrev
 867                 )->escaped();
 868
 869                 if ( $complete !== 'complete' ) {
 870                         return $header;
 871                 }
 872
 873                 $title = $rev->getTitle();
 874
 875                 $header = Linker::linkKnown( $title, $header, array(),
 876                         array( 'oldid' => $rev->getID() ) );
 877
 878                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
 879                         $editQuery = array( 'action' => 'edit' );
 880                         if ( !$rev->isCurrent() ) {
 881                                 $editQuery['oldid'] = $rev->getID();
 882                         }
 883
 884                         $msg = $this->msg( $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold' )->escaped();
 885                         $header .= ' (' . Linker::linkKnown( $title, $msg, array(), $editQuery ) . ')';
 886                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
 887                                 $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 888                         }
 889                 } else {
 890                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 891                 }
 892
 893                 return $header;
 894         }
 895
 896         /**
 897          * Add the header to a diff body
 898          *
 899          * @return string
 900          */
 901         function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
 902                 // shared.css sets diff in interface language/dir, but the actual content
 903                 // is often in a different language, mostly the page content language/dir
 904                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
 905                 $header = "<table class='$tableClass'>";
 906
 907                 if ( !$diff && !$otitle ) {
 908                         $header .= "
 909                         <tr valign='top'>
 910                         <td class='diff-ntitle'>{$ntitle}</td>
 911                         </tr>";
 912                         $multiColspan = 1;
 913                 } else {
 914                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
 915                                 $header .= "
 916                                 <col class='diff-marker' />
 917                                 <col class='diff-content' />
 918                                 <col class='diff-marker' />
 919                                 <col class='diff-content' />";
 920                                 $colspan = 2;
 921                                 $multiColspan = 4;
 922                         } else {
 923                                 $colspan = 1;
 924                                 $multiColspan = 2;
 925                         }
 926                         $header .= "
 927                         <tr valign='top'>
 928                         <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
 929                         <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
 930                         </tr>";
 931                 }
 932
 933                 if ( $multi != '' ) {
 934                         $header .= "<tr><td colspan='{$multiColspan}' align='center' class='diff-multi'>{$multi}</td></tr>";
 935                 }
 936                 if ( $notice != '' ) {
 937                         $header .= "<tr><td colspan='{$multiColspan}' align='center'>{$notice}</td></tr>";
 938                 }
 939
 940                 return $header . $diff . "</table>";
 941         }
 942
 943         /**
 944          * Use specified text instead of loading from the database
 945          */
 946         function setText( $oldText, $newText ) {
 947                 $this->mOldtext = $oldText;
 948                 $this->mNewtext = $newText;
 949                 $this->mTextLoaded = 2;
 950                 $this->mRevisionsLoaded = true;
 951         }
 952
 953         /**
 954          * Set the language in which the diff text is written
 955          * (Defaults to page content language).
 956          * @since 1.19
 957          */
 958         function setTextLanguage( $lang ) {
 959                 $this->mDiffLang = wfGetLangObj( $lang );
 960         }
 961
 962         /**
 963          * Load revision IDs
 964          */
 965         private function loadRevisionIds() {
 966                 if ( $this->mRevisionsIdsLoaded ) {
 967                         return;
 968                 }
 969
 970                 $this->mRevisionsIdsLoaded = true;
 971
 972                 $old = $this->mOldid;
 973                 $new = $this->mNewid;
 974
 975                 if ( $new === 'prev' ) {
 976                         # Show diff between revision $old and the previous one.
 977                         # Get previous one from DB.
 978                         $this->mNewid = intval( $old );
 979                         $this->mOldid = $this->getTitle()->getPreviousRevisionID( $this->mNewid );
 980                 } elseif ( $new === 'next' ) {
 981                         # Show diff between revision $old and the next one.
 982                         # Get next one from DB.
 983                         $this->mOldid = intval( $old );
 984                         $this->mNewid = $this->getTitle()->getNextRevisionID( $this->mOldid );
 985                         if ( $this->mNewid === false ) {
 986                                 # if no result, NewId points to the newest old revision. The only newer
 987                                 # revision is cur, which is "0".
 988                                 $this->mNewid = 0;
 989                         }
 990                 } else {
 991                         $this->mOldid = intval( $old );
 992                         $this->mNewid = intval( $new );
 993                         wfRunHooks( 'NewDifferenceEngine', array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ) );
 994                 }
 995         }
 996
 997         /**
 998          * Load revision metadata for the specified articles. If newid is 0, then compare
 999          * the old article in oldid to the current article; if oldid is 0, then
1000          * compare the current article to the immediately previous one (ignoring the
1001          * value of newid).
1002          *
1003          * If oldid is false, leave the corresponding revision object set
1004          * to false. This is impossible via ordinary user input, and is provided for
1005          * API convenience.
1006          *
1007          * @return bool
1008          */
1009         function loadRevisionData() {
1010                 if ( $this->mRevisionsLoaded ) {
1011                         return true;
1012                 }
1013
1014                 // Whether it succeeds or fails, we don't want to try again
1015                 $this->mRevisionsLoaded = true;
1016
1017                 $this->loadRevisionIds();
1018
1019                 // Load the new revision object
1020                 $this->mNewRev = $this->mNewid
1021                         ? Revision::newFromId( $this->mNewid )
1022                         : Revision::newFromTitle( $this->getTitle() );
1023
1024                 if ( !$this->mNewRev instanceof Revision ) {
1025                         return false;
1026                 }
1027
1028                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1029                 $this->mNewid = $this->mNewRev->getId();
1030                 $this->mNewPage = $this->mNewRev->getTitle();
1031
1032                 // Load the old revision object
1033                 $this->mOldRev = false;
1034                 if ( $this->mOldid ) {
1035                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1036                 } elseif ( $this->mOldid === 0 ) {
1037                         $rev = $this->mNewRev->getPrevious();
1038                         if ( $rev ) {
1039                                 $this->mOldid = $rev->getId();
1040                                 $this->mOldRev = $rev;
1041                         } else {
1042                                 // No previous revision; mark to show as first-version only.
1043                                 $this->mOldid = false;
1044                                 $this->mOldRev = false;
1045                         }
1046                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1047
1048                 if ( is_null( $this->mOldRev ) ) {
1049                         return false;
1050                 }
1051
1052                 if ( $this->mOldRev ) {
1053                         $this->mOldPage = $this->mOldRev->getTitle();
1054                 }
1055
1056                 return true;
1057         }
1058
1059         /**
1060          * Load the text of the revisions, as well as revision data.
1061          *
1062          * @return bool
1063          */
1064         function loadText() {
1065                 if ( $this->mTextLoaded == 2 ) {
1066                         return true;
1067                 } else {
1068                         // Whether it succeeds or fails, we don't want to try again
1069                         $this->mTextLoaded = 2;
1070                 }
1071
1072                 if ( !$this->loadRevisionData() ) {
1073                         return false;
1074                 }
1075                 if ( $this->mOldRev ) {
1076                         $this->mOldtext = $this->mOldRev->getText( Revision::FOR_THIS_USER );
1077                         if ( $this->mOldtext === false ) {
1078                                 return false;
1079                         }
1080                 }
1081                 if ( $this->mNewRev ) {
1082                         $this->mNewtext = $this->mNewRev->getText( Revision::FOR_THIS_USER );
1083                         if ( $this->mNewtext === false ) {
1084                                 return false;
1085                         }
1086                 }
1087                 return true;
1088         }
1089
1090         /**
1091          * Load the text of the new revision, not the old one
1092          *
1093          * @return bool
1094          */
1095         function loadNewText() {
1096                 if ( $this->mTextLoaded >= 1 ) {
1097                         return true;
1098                 } else {
1099                         $this->mTextLoaded = 1;
1100                 }
1101                 if ( !$this->loadRevisionData() ) {
1102                         return false;
1103                 }
1104                 $this->mNewtext = $this->mNewRev->getText( Revision::FOR_THIS_USER );
1105                 return true;
1106         }
1107 }