thumb.php

   1 <?php
   2 /**
   3  * PHP script to stream out an image thumbnail.
   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 Media
  22  */
  23
  24 define( 'MW_NO_OUTPUT_COMPRESSION', 1 );
  25 require __DIR__ . '/includes/WebStart.php';
  26
  27 // Don't use fancy mime detection, just check the file extension for jpg/gif/png
  28 $wgTrivialMimeDetection = true;
  29
  30 if ( defined( 'THUMB_HANDLER' ) ) {
  31         // Called from thumb_handler.php via 404; extract params from the URI...
  32         wfThumbHandle404();
  33 } else {
  34         // Called directly, use $_GET params
  35         wfThumbHandleRequest();
  36 }
  37
  38 wfLogProfilingData();
  39 // Commit and close up!
  40 $factory = wfGetLBFactory();
  41 $factory->commitMasterChanges();
  42 $factory->shutdown();
  43
  44 //--------------------------------------------------------------------------
  45
  46 /**
  47  * Handle a thumbnail request via query parameters
  48  *
  49  * @return void
  50  */
  51 function wfThumbHandleRequest() {
  52         $params = get_magic_quotes_gpc()
  53                 ? array_map( 'stripslashes', $_GET )
  54                 : $_GET;
  55
  56         wfStreamThumb( $params ); // stream the thumbnail
  57 }
  58
  59 /**
  60  * Handle a thumbnail request via thumbnail file URL
  61  *
  62  * @return void
  63  */
  64 function wfThumbHandle404() {
  65         global $wgArticlePath;
  66
  67         # Set action base paths so that WebRequest::getPathInfo()
  68         # recognizes the "X" as the 'title' in ../thumb_handler.php/X urls.
  69         # Note: If Custom per-extension repo paths are set, this may break.
  70         $repo = RepoGroup::singleton()->getLocalRepo();
  71         $oldArticlePath = $wgArticlePath;
  72         $wgArticlePath = $repo->getZoneUrl( 'thumb' ) . '/$1';
  73
  74         $matches = WebRequest::getPathInfo();
  75
  76         $wgArticlePath = $oldArticlePath;
  77
  78         if ( !isset( $matches['title'] ) ) {
  79                 wfThumbError( 404, 'Could not determine the name of the requested thumbnail.' );
  80                 return;
  81         }
  82
  83         $params = wfExtractThumbRequestInfo( $matches['title'] ); // basic wiki URL param extracting
  84         if ( $params == null ) {
  85                 wfThumbError( 400, 'The specified thumbnail parameters are not recognized.' );
  86                 return;
  87         }
  88
  89         wfStreamThumb( $params ); // stream the thumbnail
  90 }
  91
  92 /**
  93  * Stream a thumbnail specified by parameters
  94  *
  95  * @param array $params List of thumbnailing parameters. In addition to parameters
  96  *  passed to the MediaHandler, this may also includes the keys:
  97  *   f (for filename), archived (if archived file), temp (if temp file),
  98  *   w (alias for width), p (alias for page), r (ignored; historical),
  99  *   rel404 (path for render on 404 to verify hash path correct),
 100  *   thumbName (thumbnail name to potentially extract more parameters from
 101  *   e.g. 'lossy-page1-120px-Foo.tiff' would add page, lossy and width
 102  *   to the parameters)
 103  * @return void
 104  */
 105 function wfStreamThumb( array $params ) {
 106         global $wgVaryOnXFP;
 107
 108         $section = new ProfileSection( __METHOD__ );
 109
 110         $headers = array(); // HTTP headers to send
 111
 112         $fileName = isset( $params['f'] ) ? $params['f'] : '';
 113
 114         // Backwards compatibility parameters
 115         if ( isset( $params['w'] ) ) {
 116                 $params['width'] = $params['w'];
 117                 unset( $params['w'] );
 118         }
 119         if ( isset( $params['p'] ) ) {
 120                 $params['page'] = $params['p'];
 121         }
 122
 123         // Is this a thumb of an archived file?
 124         $isOld = ( isset( $params['archived'] ) && $params['archived'] );
 125         unset( $params['archived'] ); // handlers don't care
 126
 127         // Is this a thumb of a temp file?
 128         $isTemp = ( isset( $params['temp'] ) && $params['temp'] );
 129         unset( $params['temp'] ); // handlers don't care
 130
 131         // Some basic input validation
 132         $fileName = strtr( $fileName, '\\/', '__' );
 133
 134         // Actually fetch the image. Method depends on whether it is archived or not.
 135         if ( $isTemp ) {
 136                 $repo = RepoGroup::singleton()->getLocalRepo()->getTempRepo();
 137                 $img = new UnregisteredLocalFile( null, $repo,
 138                         # Temp files are hashed based on the name without the timestamp.
 139                         # The thumbnails will be hashed based on the entire name however.
 140                         # @todo fix this convention to actually be reasonable.
 141                         $repo->getZonePath( 'public' ) . '/' . $repo->getTempHashPath( $fileName ) . $fileName
 142                 );
 143         } elseif ( $isOld ) {
 144                 // Format is <timestamp>!<name>
 145                 $bits = explode( '!', $fileName, 2 );
 146                 if ( count( $bits ) != 2 ) {
 147                         wfThumbError( 404, wfMessage( 'badtitletext' )->text() );
 148                         return;
 149                 }
 150                 $title = Title::makeTitleSafe( NS_FILE, $bits[1] );
 151                 if ( !$title ) {
 152                         wfThumbError( 404, wfMessage( 'badtitletext' )->text() );
 153                         return;
 154                 }
 155                 $img = RepoGroup::singleton()->getLocalRepo()->newFromArchiveName( $title, $fileName );
 156         } else {
 157                 $img = wfLocalFile( $fileName );
 158         }
 159
 160         // Check the source file title
 161         if ( !$img ) {
 162                 wfThumbError( 404, wfMessage( 'badtitletext' )->text() );
 163                 return;
 164         }
 165
 166         // Check permissions if there are read restrictions
 167         $varyHeader = array();
 168         if ( !in_array( 'read', User::getGroupPermissions( array( '*' ) ), true ) ) {
 169                 if ( !$img->getTitle() || !$img->getTitle()->userCan( 'read' ) ) {
 170                         wfThumbError( 403, 'Access denied. You do not have permission to access ' .
 171                                 'the source file.' );
 172                         return;
 173                 }
 174                 $headers[] = 'Cache-Control: private';
 175                 $varyHeader[] = 'Cookie';
 176         }
 177
 178         // Check if the file is hidden
 179         if ( $img->isDeleted( File::DELETED_FILE ) ) {
 180                 wfThumbError( 404, "The source file '$fileName' does not exist." );
 181                 return;
 182         }
 183
 184         // Do rendering parameters extraction from thumbnail name.
 185         if ( isset( $params['thumbName'] ) ) {
 186                 $params = wfExtractThumbParams( $img, $params );
 187         }
 188         if ( $params == null ) {
 189                 wfThumbError( 400, 'The specified thumbnail parameters are not recognized.' );
 190                 return;
 191         }
 192
 193         // Check the source file storage path
 194         if ( !$img->exists() ) {
 195                 $redirectedLocation = false;
 196                 if ( !$isTemp ) {
 197                         // Check for file redirect
 198                         // Since redirects are associated with pages, not versions of files,
 199                         // we look for the most current version to see if its a redirect.
 200                         $possRedirFile = RepoGroup::singleton()->getLocalRepo()->findFile( $img->getName() );
 201                         if ( $possRedirFile && !is_null( $possRedirFile->getRedirected() ) ) {
 202                                 $redirTarget = $possRedirFile->getName();
 203                                 $targetFile = wfLocalFile( Title::makeTitleSafe( NS_FILE, $redirTarget ) );
 204                                 if ( $targetFile->exists() ) {
 205                                         $newThumbName = $targetFile->thumbName( $params );
 206                                         if ( $isOld ) {
 207                                                 $newThumbUrl = $targetFile->getArchiveThumbUrl(
 208                                                         $bits[0] . '!' . $targetFile->getName(), $newThumbName );
 209                                         } else {
 210                                                 $newThumbUrl = $targetFile->getThumbUrl( $newThumbName );
 211                                         }
 212                                         $redirectedLocation = wfExpandUrl( $newThumbUrl, PROTO_CURRENT );
 213                                 }
 214                         }
 215                 }
 216
 217                 if ( $redirectedLocation ) {
 218                         // File has been moved. Give redirect.
 219                         $response = RequestContext::getMain()->getRequest()->response();
 220                         $response->header( "HTTP/1.1 302 " . HttpStatus::getMessage( 302 ) );
 221                         $response->header( 'Location: ' . $redirectedLocation );
 222                         $response->header( 'Expires: ' .
 223                                 gmdate( 'D, d M Y H:i:s', time() + 12 * 3600 ) . ' GMT' );
 224                         if ( $wgVaryOnXFP ) {
 225                                 $varyHeader[] = 'X-Forwarded-Proto';
 226                         }
 227                         if ( count( $varyHeader ) ) {
 228                                 $response->header( 'Vary: ' . implode( ', ', $varyHeader ) );
 229                         }
 230                         return;
 231                 }
 232
 233                 // If its not a redirect that has a target as a local file, give 404.
 234                 wfThumbError( 404, "The source file '$fileName' does not exist." );
 235                 return;
 236         } elseif ( $img->getPath() === false ) {
 237                 wfThumbError( 500, "The source file '$fileName' is not locally accessible." );
 238                 return;
 239         }
 240
 241         // Check IMS against the source file
 242         // This means that clients can keep a cached copy even after it has been deleted on the server
 243         if ( !empty( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ) {
 244                 // Fix IE brokenness
 245                 $imsString = preg_replace( '/;.*$/', '', $_SERVER["HTTP_IF_MODIFIED_SINCE"] );
 246                 // Calculate time
 247                 wfSuppressWarnings();
 248                 $imsUnix = strtotime( $imsString );
 249                 wfRestoreWarnings();
 250                 if ( wfTimestamp( TS_UNIX, $img->getTimestamp() ) <= $imsUnix ) {
 251                         header( 'HTTP/1.1 304 Not Modified' );
 252                         return;
 253                 }
 254         }
 255
 256         $rel404 = isset( $params['rel404'] ) ? $params['rel404'] : null;
 257         unset( $params['r'] ); // ignore 'r' because we unconditionally pass File::RENDER
 258         unset( $params['f'] ); // We're done with 'f' parameter.
 259         unset( $params['rel404'] ); // moved to $rel404
 260
 261         // Get the normalized thumbnail name from the parameters...
 262         try {
 263                 $thumbName = $img->thumbName( $params );
 264                 if ( !strlen( $thumbName ) ) { // invalid params?
 265                         wfThumbError( 400, 'The specified thumbnail parameters are not valid.' );
 266                         return;
 267                 }
 268                 $thumbName2 = $img->thumbName( $params, File::THUMB_FULL_NAME ); // b/c; "long" style
 269         } catch ( MWException $e ) {
 270                 wfThumbError( 500, $e->getHTML() );
 271                 return;
 272         }
 273
 274         // For 404 handled thumbnails, we only use the the base name of the URI
 275         // for the thumb params and the parent directory for the source file name.
 276         // Check that the zone relative path matches up so squid caches won't pick
 277         // up thumbs that would not be purged on source file deletion (bug 34231).
 278         if ( $rel404 !== null ) { // thumbnail was handled via 404
 279                 if ( rawurldecode( $rel404 ) === $img->getThumbRel( $thumbName ) ) {
 280                         // Request for the canonical thumbnail name
 281                 } elseif ( rawurldecode( $rel404 ) === $img->getThumbRel( $thumbName2 ) ) {
 282                         // Request for the "long" thumbnail name; redirect to canonical name
 283                         $response = RequestContext::getMain()->getRequest()->response();
 284                         $response->header( "HTTP/1.1 301 " . HttpStatus::getMessage( 301 ) );
 285                         $response->header( 'Location: ' .
 286                                 wfExpandUrl( $img->getThumbUrl( $thumbName ), PROTO_CURRENT ) );
 287                         $response->header( 'Expires: ' .
 288                                 gmdate( 'D, d M Y H:i:s', time() + 7 * 86400 ) . ' GMT' );
 289                         if ( $wgVaryOnXFP ) {
 290                                 $varyHeader[] = 'X-Forwarded-Proto';
 291                         }
 292                         if ( count( $varyHeader ) ) {
 293                                 $response->header( 'Vary: ' . implode( ', ', $varyHeader ) );
 294                         }
 295                         return;
 296                 } else {
 297                         wfThumbError( 404, "The given path of the specified thumbnail is incorrect;
 298                                 expected '" . $img->getThumbRel( $thumbName ) . "' but got '" .
 299                                 rawurldecode( $rel404 ) . "'." );
 300                         return;
 301                 }
 302         }
 303
 304         $dispositionType = isset( $params['download'] ) ? 'attachment' : 'inline';
 305
 306         // Suggest a good name for users downloading this thumbnail
 307         $headers[] = "Content-Disposition: {$img->getThumbDisposition( $thumbName, $dispositionType )}";
 308
 309         if ( count( $varyHeader ) ) {
 310                 $headers[] = 'Vary: ' . implode( ', ', $varyHeader );
 311         }
 312
 313         // Stream the file if it exists already...
 314         $thumbPath = $img->getThumbPath( $thumbName );
 315         if ( $img->getRepo()->fileExists( $thumbPath ) ) {
 316                 $img->getRepo()->streamFile( $thumbPath, $headers );
 317                 return;
 318         }
 319
 320         $user = RequestContext::getMain()->getUser();
 321         if ( !wfThumbIsStandard( $img, $params ) && $user->pingLimiter( 'renderfile-nonstandard' ) ) {
 322                 wfThumbError( 500, wfMessage( 'actionthrottledtext' ) );
 323                 return;
 324         } elseif ( $user->pingLimiter( 'renderfile' ) ) {
 325                 wfThumbError( 500, wfMessage( 'actionthrottledtext' ) );
 326                 return;
 327         }
 328
 329         // Actually generate a new thumbnail
 330         list( $thumb, $errorMsg ) = wfGenerateThumbnail( $img, $params, $thumbName, $thumbPath );
 331
 332         // Check for thumbnail generation errors...
 333         $msg = wfMessage( 'thumbnail_error' );
 334         if ( !$thumb ) {
 335                 $errorMsg = $errorMsg ?: $msg->rawParams( 'File::transform() returned false' )->escaped();
 336         } elseif ( $thumb->isError() ) {
 337                 $errorMsg = $thumb->getHtmlMsg();
 338         } elseif ( !$thumb->hasFile() ) {
 339                 $errorMsg = $msg->rawParams( 'No path supplied in thumbnail object' )->escaped();
 340         } elseif ( $thumb->fileIsSource() ) {
 341                 $errorMsg = $msg->
 342                         rawParams( 'Image was not scaled, is the requested width bigger than the source?' )->escaped();
 343         }
 344
 345         if ( $errorMsg !== false ) {
 346                 wfThumbError( 500, $errorMsg );
 347         } else {
 348                 // Stream the file if there were no errors
 349                 $thumb->streamFile( $headers );
 350         }
 351 }
 352
 353 /**
 354  * Actually try to generate a new thumbnail
 355  *
 356  * @param File $file
 357  * @param array $params
 358  * @param string $thumbName
 359  * @param string $thumbPath
 360  * @return array (MediaTransformOutput|bool, string|bool error message HTML)
 361  */
 362 function wfGenerateThumbnail( File $file, array $params, $thumbName, $thumbPath ) {
 363         global $wgMemc, $wgAttemptFailureEpoch;
 364
 365         $key = wfMemcKey( 'attempt-failures', $wgAttemptFailureEpoch,
 366                 $file->getRepo()->getName(), md5( $file->getName() ), md5( $thumbName ) );
 367
 368         // Check if this file keeps failing to render
 369         if ( $wgMemc->get( $key ) >= 4 ) {
 370                 return array( false, wfMessage( 'thumbnail_image-failure-limit', 4 ) );
 371         }
 372
 373         $done = false;
 374         // Record failures on PHP fatals in addition to caching exceptions
 375         register_shutdown_function( function() use ( &$done, $key ) {
 376                 if ( !$done ) { // transform() gave a fatal
 377                         global $wgMemc;
 378                         // Randomize TTL to reduce stampedes
 379                         $wgMemc->incrWithInit( $key, 3600 + mt_rand( 0, 300 ) );
 380                 }
 381         } );
 382
 383         $thumb = false;
 384         $errorHtml = false;
 385
 386         // Thumbnail isn't already there, so create the new thumbnail...
 387         try {
 388                 $work = new PoolCounterWorkViaCallback( 'FileRender', sha1( $file->getName() ),
 389                         array(
 390                                 'doWork' => function() use ( $file, $params ) {
 391                                         return $file->transform( $params, File::RENDER_NOW );
 392                                 },
 393                                 'getCachedWork' => function() use ( $file, $params, $thumbPath ) {
 394                                         // If the worker that finished made this thumbnail then use it.
 395                                         // Otherwise, it probably made a different thumbnail for this file.
 396                                         return $file->getRepo()->fileExists( $thumbPath )
 397                                                 ? $file->transform( $params, File::RENDER_NOW )
 398                                                 : false; // retry once more in exclusive mode
 399                                 },
 400                                 'fallback' => function() {
 401                                         return wfMessage( 'generic-pool-error' )->parse();
 402                                 },
 403                                 'error' => function ( $status ) {
 404                                         return $status->getHTML();
 405                                 }
 406                         )
 407                 );
 408                 $result = $work->execute();
 409                 if ( $result instanceof MediaTransformOutput ) {
 410                         $thumb = $result;
 411                 } elseif ( is_string( $result ) ) { // error
 412                         $errorHtml = $result;
 413                 }
 414         } catch ( Exception $e ) {
 415                 // Tried to select a page on a non-paged file?
 416         }
 417
 418         $done = true; // no PHP fatal occured
 419
 420         if ( !$thumb || $thumb->isError() ) {
 421                 // Randomize TTL to reduce stampedes
 422                 $wgMemc->incrWithInit( $key, 3600 + mt_rand( 0, 300 ) );
 423         }
 424
 425         return array( $thumb, $errorHtml );
 426 }
 427
 428 /**
 429  * Returns true if this thumbnail is one that MediaWiki generates
 430  * links to on file description pages and possibly parser output.
 431  *
 432  * $params is considered non-standard if they involve a non-standard
 433  * width or any non-default parameters aside from width and page number.
 434  * The number of possible files with standard parameters is far less than
 435  * that of all combinations; rate-limiting for them can thus be more generious.
 436  *
 437  * @param File $file
 438  * @param array $params
 439  * @return bool
 440  */
 441 function wfThumbIsStandard( File $file, array $params ) {
 442         global $wgThumbLimits, $wgImageLimits;
 443
 444         $handler = $file->getHandler();
 445         if ( !$handler || !isset( $params['width'] ) ) {
 446                 return false;
 447         }
 448
 449         $basicParams = array();
 450         if ( isset( $params['page'] ) ) {
 451                 $basicParams['page'] = $params['page'];
 452         }
 453
 454         // Check if the width matches one of $wgThumbLimits
 455         if ( in_array( $params['width'], $wgThumbLimits ) ) {
 456                 $normalParams = $basicParams + array( 'width' => $params['width'] );
 457                 // Append any default values to the map (e.g. "lossy", "lossless", ...)
 458                 $handler->normaliseParams( $file, $normalParams );
 459         } else {
 460                 // If not, then check if the width matchs one of $wgImageLimits
 461                 $match = false;
 462                 foreach ( $wgImageLimits as $pair ) {
 463                         $normalParams = $basicParams + array( 'width' => $pair[0], 'height' => $pair[1] );
 464                         // Decide whether the thumbnail should be scaled on width or height.
 465                         // Also append any default values to the map (e.g. "lossy", "lossless", ...)
 466                         $handler->normaliseParams( $file, $normalParams );
 467                         // Check if this standard thumbnail size maps to the given width
 468                         if ( $normalParams['width'] == $params['width'] ) {
 469                                 $match = true;
 470                                 break;
 471                         }
 472                 }
 473                 if ( !$match ) {
 474                         return false; // not standard for description pages
 475                 }
 476         }
 477
 478         // Check that the given values for non-page, non-width, params are just defaults
 479         foreach ( $params as $key => $value ) {
 480                 if ( !isset( $normalParams[$key] ) || $normalParams[$key] != $value ) {
 481                         return false;
 482                 }
 483         }
 484
 485         return true;
 486 }
 487
 488 /**
 489  * Convert pathinfo type parameter, into normal request parameters
 490  *
 491  * So for example, if the request was redirected from
 492  * /w/images/thumb/a/ab/Foo.png/120px-Foo.png. The $thumbRel parameter
 493  * of this function would be set to "a/ab/Foo.png/120px-Foo.png".
 494  * This method is responsible for turning that into an array
 495  * with the folowing keys:
 496  *  * f => the filename (Foo.png)
 497  *  * rel404 => the whole thing (a/ab/Foo.png/120px-Foo.png)
 498  *  * archived => 1 (If the request is for an archived thumb)
 499  *  * temp => 1 (If the file is in the "temporary" zone)
 500  *  * thumbName => the thumbnail name, including parameters (120px-Foo.png)
 501  *
 502  * Transform specific parameters are set later via wfExtractThumbParams().
 503  *
 504  * @param string $thumbRel Thumbnail path relative to the thumb zone
 505  * @return array|null Associative params array or null
 506  */
 507 function wfExtractThumbRequestInfo( $thumbRel ) {
 508         $repo = RepoGroup::singleton()->getLocalRepo();
 509
 510         $hashDirReg = $subdirReg = '';
 511         for ( $i = 0; $i < $repo->getHashLevels(); $i++ ) {
 512                 $subdirReg .= '[0-9a-f]';
 513                 $hashDirReg .= "$subdirReg/";
 514         }
 515
 516         // Check if this is a thumbnail of an original in the local file repo
 517         if ( preg_match( "!^((archive/)?$hashDirReg([^/]*)/([^/]*))$!", $thumbRel, $m ) ) {
 518                 list( /*all*/, $rel, $archOrTemp, $filename, $thumbname ) = $m;
 519         // Check if this is a thumbnail of an temp file in the local file repo
 520         } elseif ( preg_match( "!^(temp/)($hashDirReg([^/]*)/([^/]*))$!", $thumbRel, $m ) ) {
 521                 list( /*all*/, $archOrTemp, $rel, $filename, $thumbname ) = $m;
 522         } else {
 523                 return null; // not a valid looking thumbnail request
 524         }
 525
 526         $params = array( 'f' => $filename, 'rel404' => $rel );
 527         if ( $archOrTemp === 'archive/' ) {
 528                 $params['archived'] = 1;
 529         } elseif ( $archOrTemp === 'temp/' ) {
 530                 $params['temp'] = 1;
 531         }
 532
 533         $params['thumbName'] = $thumbname;
 534         return $params;
 535 }
 536
 537 /**
 538  * Convert a thumbnail name (122px-foo.png) to parameters, using
 539  * file handler.
 540  *
 541  * @param File $file File object for file in question
 542  * @param array $param Array of parameters so far
 543  * @return array Parameters array with more parameters
 544  */
 545 function wfExtractThumbParams( $file, $params ) {
 546         if ( !isset( $params['thumbName'] ) ) {
 547                 throw new MWException( "No thumbnail name passed to wfExtractThumbParams" );
 548         }
 549
 550         $thumbname = $params['thumbName'];
 551         unset( $params['thumbName'] );
 552
 553         // Do the hook first for older extensions that rely on it.
 554         if ( !wfRunHooks( 'ExtractThumbParameters', array( $thumbname, &$params ) ) ) {
 555                 // Check hooks if parameters can be extracted
 556                 // Hooks return false if they manage to *resolve* the parameters
 557                 // This hook should be considered deprecated
 558                 wfDeprecated( 'ExtractThumbParameters', '1.22' );
 559                 return $params; // valid thumbnail URL (via extension or config)
 560         }
 561
 562         // FIXME: Files in the temp zone don't set a mime type, which means
 563         // they don't have a handler. Which means we can't parse the param
 564         // string. However, not a big issue as what good is a param string
 565         // if you have no handler to make use of the param string and
 566         // actually generate the thumbnail.
 567         $handler = $file->getHandler();
 568
 569         // Based on UploadStash::parseKey
 570         $fileNamePos = strrpos( $thumbname, $params['f'] );
 571         if ( $fileNamePos === false ) {
 572                 // Maybe using a short filename? (see FileRepo::nameForThumb)
 573                 $fileNamePos = strrpos( $thumbname, 'thumbnail' );
 574         }
 575
 576         if ( $handler && $fileNamePos !== false ) {
 577                 $paramString = substr( $thumbname, 0, $fileNamePos - 1 );
 578                 $extraParams = $handler->parseParamString( $paramString );
 579                 if ( $extraParams !== false ) {
 580                         return $params + $extraParams;
 581                 }
 582         }
 583
 584         // As a last ditch fallback, use the traditional common parameters
 585         if ( preg_match( '!^(page(\d*)-)*(\d*)px-[^/]*$!', $thumbname, $matches ) ) {
 586                 list( /* all */, $pagefull, $pagenum, $size ) = $matches;
 587                 $params['width'] = $size;
 588                 if ( $pagenum ) {
 589                         $params['page'] = $pagenum;
 590                 }
 591                 return $params; // valid thumbnail URL
 592         }
 593         return null;
 594 }
 595
 596 /**
 597  * Output a thumbnail generation error message
 598  *
 599  * @param int $status
 600  * @param string $msg
 601  * @return void
 602  */
 603 function wfThumbError( $status, $msg ) {
 604         global $wgShowHostnames;
 605
 606         header( 'Cache-Control: no-cache' );
 607         header( 'Content-Type: text/html; charset=utf-8' );
 608         if ( $status == 404 ) {
 609                 header( 'HTTP/1.1 404 Not found' );
 610         } elseif ( $status == 403 ) {
 611                 header( 'HTTP/1.1 403 Forbidden' );
 612                 header( 'Vary: Cookie' );
 613         } else {
 614                 header( 'HTTP/1.1 500 Internal server error' );
 615         }
 616         if ( $wgShowHostnames ) {
 617                 header( 'X-MW-Thumbnail-Renderer: ' . wfHostname() );
 618                 $url = htmlspecialchars( isset( $_SERVER['REQUEST_URI'] ) ? $_SERVER['REQUEST_URI'] : '' );
 619                 $hostname = htmlspecialchars( wfHostname() );
 620                 $debug = "<!-- $url -->\n<!-- $hostname -->\n";
 621         } else {
 622                 $debug = '';
 623         }
 624         echo <<<EOT
 625 <html><head><title>Error generating thumbnail</title></head>
 626 <body>
 627 <h1>Error generating thumbnail</h1>
 628 <p>
 629 $msg
 630 </p>
 631 $debug
 632 </body>
 633 </html>
 634
 635 EOT;
 636 }