includes/libs/mime/MimeAnalyzer.php

   1 <?php
   2 /**
   3  * Module defining helper functions for detecting and dealing with MIME types.
   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  */
  22 use Psr\Log\LoggerAwareInterface;
  23 use Psr\Log\LoggerInterface;
  24 use Psr\Log\NullLogger;
  25
  26 /**
  27  * Implements functions related to MIME types such as detection and mapping to file extension
  28  *
  29  * @since 1.28
  30  */
  31 class MimeAnalyzer implements LoggerAwareInterface {
  32         /** @var string */
  33         protected $typeFile;
  34         /** @var string */
  35         protected $infoFile;
  36         /** @var string */
  37         protected $xmlTypes;
  38         /** @var callable */
  39         protected $initCallback;
  40         /** @var callable */
  41         protected $detectCallback;
  42         /** @var callable */
  43         protected $guessCallback;
  44         /** @var callable */
  45         protected $extCallback;
  46         /** @var array Mapping of media types to arrays of MIME types */
  47         protected $mediaTypes = null;
  48         /** @var array Map of MIME type aliases */
  49         protected $mimeTypeAliases = null;
  50         /** @var array Map of MIME types to file extensions (as a space separated list) */
  51         protected $mimetoExt = null;
  52
  53         /** @var array Map of file extensions types to MIME types (as a space separated list) */
  54         public $mExtToMime = null; // legacy name; field accessed by hooks
  55
  56         /** @var IEContentAnalyzer */
  57         protected $IEAnalyzer;
  58
  59         /** @var string Extra MIME types, set for example by media handling extensions */
  60         private $extraTypes = '';
  61         /** @var string Extra MIME info, set for example by media handling extensions */
  62         private $extraInfo = '';
  63
  64         /** @var LoggerInterface */
  65         private $logger;
  66
  67         /**
  68          * Defines a set of well known MIME types
  69          * This is used as a fallback to mime.types files.
  70          * An extensive list of well known MIME types is provided by
  71          * the file mime.types in the includes directory.
  72          *
  73          * This list concatenated with mime.types is used to create a MIME <-> ext
  74          * map. Each line contains a MIME type followed by a space separated list of
  75          * extensions. If multiple extensions for a single MIME type exist or if
  76          * multiple MIME types exist for a single extension then in most cases
  77          * MediaWiki assumes that the first extension following the MIME type is the
  78          * canonical extension, and the first time a MIME type appears for a certain
  79          * extension is considered the canonical MIME type.
  80          *
  81          * (Note that appending the type file list to the end of self::$wellKnownTypes
  82          * sucks because you can't redefine canonical types. This could be fixed by
  83          * appending self::$wellKnownTypes behind type file list, but who knows
  84          * what will break? In practice this probably isn't a problem anyway -- Bryan)
  85          */
  86         protected static $wellKnownTypes = <<<EOT
  87 application/ogg ogx ogg ogm ogv oga spx opus
  88 application/pdf pdf
  89 application/vnd.oasis.opendocument.chart odc
  90 application/vnd.oasis.opendocument.chart-template otc
  91 application/vnd.oasis.opendocument.database odb
  92 application/vnd.oasis.opendocument.formula odf
  93 application/vnd.oasis.opendocument.formula-template otf
  94 application/vnd.oasis.opendocument.graphics odg
  95 application/vnd.oasis.opendocument.graphics-template otg
  96 application/vnd.oasis.opendocument.image odi
  97 application/vnd.oasis.opendocument.image-template oti
  98 application/vnd.oasis.opendocument.presentation odp
  99 application/vnd.oasis.opendocument.presentation-template otp
 100 application/vnd.oasis.opendocument.spreadsheet ods
 101 application/vnd.oasis.opendocument.spreadsheet-template ots
 102 application/vnd.oasis.opendocument.text odt
 103 application/vnd.oasis.opendocument.text-master otm
 104 application/vnd.oasis.opendocument.text-template ott
 105 application/vnd.oasis.opendocument.text-web oth
 106 application/javascript js
 107 application/x-shockwave-flash swf
 108 audio/midi mid midi kar
 109 audio/mpeg mpga mpa mp2 mp3
 110 audio/x-aiff aif aiff aifc
 111 audio/x-wav wav
 112 audio/ogg oga spx ogg opus
 113 audio/opus opus ogg oga ogg spx
 114 image/x-bmp bmp
 115 image/gif gif
 116 image/jpeg jpeg jpg jpe
 117 image/png png
 118 image/svg+xml svg
 119 image/svg svg
 120 image/tiff tiff tif
 121 image/vnd.djvu djvu
 122 image/x.djvu djvu
 123 image/x-djvu djvu
 124 image/x-portable-pixmap ppm
 125 image/x-xcf xcf
 126 text/plain txt
 127 text/html html htm
 128 video/ogg ogv ogm ogg
 129 video/mpeg mpg mpeg
 130 EOT;
 131
 132         /**
 133          * Defines a set of well known MIME info entries
 134          * This is used as a fallback to mime.info files.
 135          * An extensive list of well known MIME types is provided by
 136          * the file mime.info in the includes directory.
 137          */
 138         protected static $wellKnownInfo = <<<EOT
 139 application/pdf [OFFICE]
 140 application/vnd.oasis.opendocument.chart [OFFICE]
 141 application/vnd.oasis.opendocument.chart-template [OFFICE]
 142 application/vnd.oasis.opendocument.database [OFFICE]
 143 application/vnd.oasis.opendocument.formula [OFFICE]
 144 application/vnd.oasis.opendocument.formula-template [OFFICE]
 145 application/vnd.oasis.opendocument.graphics [OFFICE]
 146 application/vnd.oasis.opendocument.graphics-template [OFFICE]
 147 application/vnd.oasis.opendocument.image [OFFICE]
 148 application/vnd.oasis.opendocument.image-template [OFFICE]
 149 application/vnd.oasis.opendocument.presentation [OFFICE]
 150 application/vnd.oasis.opendocument.presentation-template [OFFICE]
 151 application/vnd.oasis.opendocument.spreadsheet [OFFICE]
 152 application/vnd.oasis.opendocument.spreadsheet-template [OFFICE]
 153 application/vnd.oasis.opendocument.text [OFFICE]
 154 application/vnd.oasis.opendocument.text-template [OFFICE]
 155 application/vnd.oasis.opendocument.text-master [OFFICE]
 156 application/vnd.oasis.opendocument.text-web [OFFICE]
 157 application/javascript text/javascript application/x-javascript [EXECUTABLE]
 158 application/x-shockwave-flash [MULTIMEDIA]
 159 audio/midi [AUDIO]
 160 audio/x-aiff [AUDIO]
 161 audio/x-wav [AUDIO]
 162 audio/mp3 audio/mpeg [AUDIO]
 163 application/ogg audio/ogg video/ogg [MULTIMEDIA]
 164 image/x-bmp image/x-ms-bmp image/bmp [BITMAP]
 165 image/gif [BITMAP]
 166 image/jpeg [BITMAP]
 167 image/png [BITMAP]
 168 image/svg+xml [DRAWING]
 169 image/tiff [BITMAP]
 170 image/vnd.djvu [BITMAP]
 171 image/x-xcf [BITMAP]
 172 image/x-portable-pixmap [BITMAP]
 173 text/plain [TEXT]
 174 text/html [TEXT]
 175 video/ogg [VIDEO]
 176 video/mpeg [VIDEO]
 177 unknown/unknown application/octet-stream application/x-empty [UNKNOWN]
 178 EOT;
 179
 180         /**
 181          * @param array $params Configuration map, includes:
 182          *   - typeFile: path to file with the list of known MIME types
 183          *   - infoFile: path to file with the MIME type info
 184          *   - xmlTypes: map of root element names to XML MIME types
 185          *   - initCallback: initialization callback that is passed this object [optional]
 186          *   - detectCallback: alternative to finfo that returns the mime type for a file.
 187          *      For example, the callback can return the output of "file -bi". [optional]
 188          *   - guessCallback: callback to improve the guessed MIME type using the file data.
 189          *      This is intended for fixing mistakes in fileinfo or "detectCallback". [optional]
 190          *   - extCallback: callback to improve the guessed MIME type using the extension. [optional]
 191          *   - logger: PSR-3 logger [optional]
 192          * @note Constructing these instances is expensive due to file reads.
 193          *  A service or singleton pattern should be used to avoid creating instances again and again.
 194          */
 195         public function __construct( array $params ) {
 196                 $this->typeFile = $params['typeFile'];
 197                 $this->infoFile = $params['infoFile'];
 198                 $this->xmlTypes = $params['xmlTypes'];
 199                 $this->initCallback = $params['initCallback'] ?? null;
 200                 $this->detectCallback = $params['detectCallback'] ?? null;
 201                 $this->guessCallback = $params['guessCallback'] ?? null;
 202                 $this->extCallback = $params['extCallback'] ?? null;
 203                 $this->logger = $params['logger'] ?? new NullLogger();
 204
 205                 $this->loadFiles();
 206         }
 207
 208         protected function loadFiles() {
 209                 /**
 210                  *   --- load mime.types ---
 211                  */
 212
 213                 # Allow media handling extensions adding MIME-types and MIME-info
 214                 if ( $this->initCallback ) {
 215                         call_user_func( $this->initCallback, $this );
 216                 }
 217
 218                 $types = self::$wellKnownTypes;
 219
 220                 $mimeTypeFile = $this->typeFile;
 221                 if ( $mimeTypeFile ) {
 222                         if ( is_file( $mimeTypeFile ) && is_readable( $mimeTypeFile ) ) {
 223                                 $this->logger->info( __METHOD__ . ": loading mime types from $mimeTypeFile\n" );
 224                                 $types .= "\n";
 225                                 $types .= file_get_contents( $mimeTypeFile );
 226                         } else {
 227                                 $this->logger->info( __METHOD__ . ": can't load mime types from $mimeTypeFile\n" );
 228                         }
 229                 } else {
 230                         $this->logger->info( __METHOD__ .
 231                                 ": no mime types file defined, using built-ins only.\n" );
 232                 }
 233
 234                 $types .= "\n" . $this->extraTypes;
 235
 236                 $types = str_replace( [ "\r\n", "\n\r", "\n\n", "\r\r", "\r" ], "\n", $types );
 237                 $types = str_replace( "\t", " ", $types );
 238
 239                 $this->mimetoExt = [];
 240                 $this->mExtToMime = [];
 241
 242                 $lines = explode( "\n", $types );
 243                 foreach ( $lines as $s ) {
 244                         $s = trim( $s );
 245                         if ( empty( $s ) ) {
 246                                 continue;
 247                         }
 248                         if ( strpos( $s, '#' ) === 0 ) {
 249                                 continue;
 250                         }
 251
 252                         $s = strtolower( $s );
 253                         $i = strpos( $s, ' ' );
 254
 255                         if ( $i === false ) {
 256                                 continue;
 257                         }
 258
 259                         $mime = substr( $s, 0, $i );
 260                         $ext = trim( substr( $s, $i + 1 ) );
 261
 262                         if ( empty( $ext ) ) {
 263                                 continue;
 264                         }
 265
 266                         if ( !empty( $this->mimetoExt[$mime] ) ) {
 267                                 $this->mimetoExt[$mime] .= ' ' . $ext;
 268                         } else {
 269                                 $this->mimetoExt[$mime] = $ext;
 270                         }
 271
 272                         $extensions = explode( ' ', $ext );
 273
 274                         foreach ( $extensions as $e ) {
 275                                 $e = trim( $e );
 276                                 if ( empty( $e ) ) {
 277                                         continue;
 278                                 }
 279
 280                                 if ( !empty( $this->mExtToMime[$e] ) ) {
 281                                         $this->mExtToMime[$e] .= ' ' . $mime;
 282                                 } else {
 283                                         $this->mExtToMime[$e] = $mime;
 284                                 }
 285                         }
 286                 }
 287
 288                 /**
 289                  *   --- load mime.info ---
 290                  */
 291
 292                 $mimeInfoFile = $this->infoFile;
 293
 294                 $info = self::$wellKnownInfo;
 295
 296                 if ( $mimeInfoFile ) {
 297                         if ( is_file( $mimeInfoFile ) && is_readable( $mimeInfoFile ) ) {
 298                                 $this->logger->info( __METHOD__ . ": loading mime info from $mimeInfoFile\n" );
 299                                 $info .= "\n";
 300                                 $info .= file_get_contents( $mimeInfoFile );
 301                         } else {
 302                                 $this->logger->info( __METHOD__ . ": can't load mime info from $mimeInfoFile\n" );
 303                         }
 304                 } else {
 305                         $this->logger->info( __METHOD__ .
 306                                 ": no mime info file defined, using built-ins only.\n" );
 307                 }
 308
 309                 $info .= "\n" . $this->extraInfo;
 310
 311                 $info = str_replace( [ "\r\n", "\n\r", "\n\n", "\r\r", "\r" ], "\n", $info );
 312                 $info = str_replace( "\t", " ", $info );
 313
 314                 $this->mimeTypeAliases = [];
 315                 $this->mediaTypes = [];
 316
 317                 $lines = explode( "\n", $info );
 318                 foreach ( $lines as $s ) {
 319                         $s = trim( $s );
 320                         if ( empty( $s ) ) {
 321                                 continue;
 322                         }
 323                         if ( strpos( $s, '#' ) === 0 ) {
 324                                 continue;
 325                         }
 326
 327                         $s = strtolower( $s );
 328                         $i = strpos( $s, ' ' );
 329
 330                         if ( $i === false ) {
 331                                 continue;
 332                         }
 333
 334                         # print "processing MIME INFO line $s<br>";
 335
 336                         $match = [];
 337                         if ( preg_match( '!\[\s*(\w+)\s*\]!', $s, $match ) ) {
 338                                 $s = preg_replace( '!\[\s*(\w+)\s*\]!', '', $s );
 339                                 $mtype = trim( strtoupper( $match[1] ) );
 340                         } else {
 341                                 $mtype = MEDIATYPE_UNKNOWN;
 342                         }
 343
 344                         $m = explode( ' ', $s );
 345
 346                         if ( !isset( $this->mediaTypes[$mtype] ) ) {
 347                                 $this->mediaTypes[$mtype] = [];
 348                         }
 349
 350                         foreach ( $m as $mime ) {
 351                                 $mime = trim( $mime );
 352                                 if ( empty( $mime ) ) {
 353                                         continue;
 354                                 }
 355
 356                                 $this->mediaTypes[$mtype][] = $mime;
 357                         }
 358
 359                         if ( count( $m ) > 1 ) {
 360                                 $main = $m[0];
 361                                 $mCount = count( $m );
 362                                 for ( $i = 1; $i < $mCount; $i += 1 ) {
 363                                         $mime = $m[$i];
 364                                         $this->mimeTypeAliases[$mime] = $main;
 365                                 }
 366                         }
 367                 }
 368         }
 369
 370         public function setLogger( LoggerInterface $logger ) {
 371                 $this->logger = $logger;
 372         }
 373
 374         /**
 375          * Adds to the list mapping MIME to file extensions.
 376          * As an extension author, you are encouraged to submit patches to
 377          * MediaWiki's core to add new MIME types to mime.types.
 378          * @param string $types
 379          */
 380         public function addExtraTypes( $types ) {
 381                 $this->extraTypes .= "\n" . $types;
 382         }
 383
 384         /**
 385          * Adds to the list mapping MIME to media type.
 386          * As an extension author, you are encouraged to submit patches to
 387          * MediaWiki's core to add new MIME info to mime.info.
 388          * @param string $info
 389          */
 390         public function addExtraInfo( $info ) {
 391                 $this->extraInfo .= "\n" . $info;
 392         }
 393
 394         /**
 395          * Returns a list of file extensions for a given MIME type as a space
 396          * separated string or null if the MIME type was unrecognized. Resolves
 397          * MIME type aliases.
 398          *
 399          * @param string $mime
 400          * @return string|null
 401          */
 402         public function getExtensionsForType( $mime ) {
 403                 $mime = strtolower( $mime );
 404
 405                 // Check the mime-to-ext map
 406                 if ( isset( $this->mimetoExt[$mime] ) ) {
 407                         return $this->mimetoExt[$mime];
 408                 }
 409
 410                 // Resolve the MIME type to the canonical type
 411                 if ( isset( $this->mimeTypeAliases[$mime] ) ) {
 412                         $mime = $this->mimeTypeAliases[$mime];
 413                         if ( isset( $this->mimetoExt[$mime] ) ) {
 414                                 return $this->mimetoExt[$mime];
 415                         }
 416                 }
 417
 418                 return null;
 419         }
 420
 421         /**
 422          * Returns a list of MIME types for a given file extension as a space
 423          * separated string or null if the extension was unrecognized.
 424          *
 425          * @param string $ext
 426          * @return string|null
 427          */
 428         public function getTypesForExtension( $ext ) {
 429                 $ext = strtolower( $ext );
 430
 431                 $r = $this->mExtToMime[$ext] ?? null;
 432                 return $r;
 433         }
 434
 435         /**
 436          * Returns a single MIME type for a given file extension or null if unknown.
 437          * This is always the first type from the list returned by getTypesForExtension($ext).
 438          *
 439          * @param string $ext
 440          * @return string|null
 441          */
 442         public function guessTypesForExtension( $ext ) {
 443                 $m = $this->getTypesForExtension( $ext );
 444                 if ( is_null( $m ) ) {
 445                         return null;
 446                 }
 447
 448                 // TODO: Check if this is needed; strtok( $m, ' ' ) should be sufficient
 449                 $m = trim( $m );
 450                 $m = preg_replace( '/\s.*$/', '', $m );
 451
 452                 return $m;
 453         }
 454
 455         /**
 456          * Tests if the extension matches the given MIME type. Returns true if a
 457          * match was found, null if the MIME type is unknown, and false if the
 458          * MIME type is known but no matches where found.
 459          *
 460          * @param string $extension
 461          * @param string $mime
 462          * @return bool|null
 463          */
 464         public function isMatchingExtension( $extension, $mime ) {
 465                 $ext = $this->getExtensionsForType( $mime );
 466
 467                 if ( !$ext ) {
 468                         return null; // Unknown MIME type
 469                 }
 470
 471                 $ext = explode( ' ', $ext );
 472
 473                 $extension = strtolower( $extension );
 474                 return in_array( $extension, $ext );
 475         }
 476
 477         /**
 478          * Returns true if the MIME type is known to represent an image format
 479          * supported by the PHP GD library.
 480          *
 481          * @param string $mime
 482          *
 483          * @return bool
 484          */
 485         public function isPHPImageType( $mime ) {
 486                 // As defined by imagegetsize and image_type_to_mime
 487                 static $types = [
 488                         'image/gif', 'image/jpeg', 'image/png',
 489                         'image/x-bmp', 'image/xbm', 'image/tiff',
 490                         'image/jp2', 'image/jpeg2000', 'image/iff',
 491                         'image/xbm', 'image/x-xbitmap',
 492                         'image/vnd.wap.wbmp', 'image/vnd.xiff',
 493                         'image/x-photoshop',
 494                         'application/x-shockwave-flash',
 495                 ];
 496
 497                 return in_array( $mime, $types );
 498         }
 499
 500         /**
 501          * Returns true if the extension represents a type which can
 502          * be reliably detected from its content. Use this to determine
 503          * whether strict content checks should be applied to reject
 504          * invalid uploads; if we can't identify the type we won't
 505          * be able to say if it's invalid.
 506          *
 507          * @todo Be more accurate when using fancy MIME detector plugins;
 508          *       right now this is the bare minimum getimagesize() list.
 509          * @param string $extension
 510          * @return bool
 511          */
 512         function isRecognizableExtension( $extension ) {
 513                 static $types = [
 514                         // Types recognized by getimagesize()
 515                         'gif', 'jpeg', 'jpg', 'png', 'swf', 'psd',
 516                         'bmp', 'tiff', 'tif', 'jpc', 'jp2',
 517                         'jpx', 'jb2', 'swc', 'iff', 'wbmp',
 518                         'xbm',
 519
 520                         // Formats we recognize magic numbers for
 521                         'djvu', 'ogx', 'ogg', 'ogv', 'oga', 'spx', 'opus',
 522                         'mid', 'pdf', 'wmf', 'xcf', 'webm', 'mkv', 'mka',
 523                         'webp', 'mp3',
 524
 525                         // XML formats we sure hope we recognize reliably
 526                         'svg',
 527
 528                         // 3D formats
 529                         'stl',
 530                 ];
 531                 return in_array( strtolower( $extension ), $types );
 532         }
 533
 534         /**
 535          * Improves a MIME type using the file extension. Some file formats are very generic,
 536          * so their MIME type is not very meaningful. A more useful MIME type can be derived
 537          * by looking at the file extension. Typically, this method would be called on the
 538          * result of guessMimeType().
 539          *
 540          * @param string $mime The MIME type, typically guessed from a file's content.
 541          * @param string $ext The file extension, as taken from the file name
 542          *
 543          * @return string The MIME type
 544          */
 545         public function improveTypeFromExtension( $mime, $ext ) {
 546                 if ( $mime === 'unknown/unknown' ) {
 547                         if ( $this->isRecognizableExtension( $ext ) ) {
 548                                 $this->logger->info( __METHOD__ . ': refusing to guess mime type for .' .
 549                                         "$ext file, we should have recognized it\n" );
 550                         } else {
 551                                 // Not something we can detect, so simply
 552                                 // trust the file extension
 553                                 $mime = $this->guessTypesForExtension( $ext );
 554                         }
 555                 } elseif ( $mime === 'application/x-opc+zip' ) {
 556                         if ( $this->isMatchingExtension( $ext, $mime ) ) {
 557                                 // A known file extension for an OPC file,
 558                                 // find the proper MIME type for that file extension
 559                                 $mime = $this->guessTypesForExtension( $ext );
 560                         } else {
 561                                 $this->logger->info( __METHOD__ .
 562                                         ": refusing to guess better type for $mime file, " .
 563                                         ".$ext is not a known OPC extension.\n" );
 564                                 $mime = 'application/zip';
 565                         }
 566                 } elseif ( $mime === 'text/plain' && $this->findMediaType( ".$ext" ) === MEDIATYPE_TEXT ) {
 567                         // Textual types are sometimes not recognized properly.
 568                         // If detected as text/plain, and has an extension which is textual
 569                         // improve to the extension's type. For example, csv and json are often
 570                         // misdetected as text/plain.
 571                         $mime = $this->guessTypesForExtension( $ext );
 572                 }
 573
 574                 # Media handling extensions can improve the MIME detected
 575                 $callback = $this->extCallback;
 576                 if ( $callback ) {
 577                         $callback( $this, $ext, $mime /* by reference */ );
 578                 }
 579
 580                 if ( isset( $this->mimeTypeAliases[$mime] ) ) {
 581                         $mime = $this->mimeTypeAliases[$mime];
 582                 }
 583
 584                 $this->logger->info( __METHOD__ . ": improved mime type for .$ext: $mime\n" );
 585                 return $mime;
 586         }
 587
 588         /**
 589          * MIME type detection. This uses detectMimeType to detect the MIME type
 590          * of the file, but applies additional checks to determine some well known
 591          * file formats that may be missed or misinterpreted by the default MIME
 592          * detection (namely XML based formats like XHTML or SVG, as well as ZIP
 593          * based formats like OPC/ODF files).
 594          *
 595          * @param string $file The file to check
 596          * @param string|bool $ext The file extension, or true (default) to extract
 597          *   it from the filename. Set it to false to ignore the extension. DEPRECATED!
 598          *   Set to false, use improveTypeFromExtension($mime, $ext) later to improve MIME type.
 599          *
 600          * @return string The MIME type of $file
 601          */
 602         public function guessMimeType( $file, $ext = true ) {
 603                 if ( $ext ) { // TODO: make $ext default to false. Or better, remove it.
 604                         $this->logger->info( __METHOD__ .
 605                                 ": WARNING: use of the \$ext parameter is deprecated. " .
 606                                 "Use improveTypeFromExtension(\$mime, \$ext) instead.\n" );
 607                 }
 608
 609                 $mime = $this->doGuessMimeType( $file, $ext );
 610
 611                 if ( !$mime ) {
 612                         $this->logger->info( __METHOD__ .
 613                                 ": internal type detection failed for $file (.$ext)...\n" );
 614                         $mime = $this->detectMimeType( $file, $ext );
 615                 }
 616
 617                 if ( isset( $this->mimeTypeAliases[$mime] ) ) {
 618                         $mime = $this->mimeTypeAliases[$mime];
 619                 }
 620
 621                 $this->logger->info( __METHOD__ . ": guessed mime type of $file: $mime\n" );
 622                 return $mime;
 623         }
 624
 625         /**
 626          * Guess the MIME type from the file contents.
 627          *
 628          * @todo Remove $ext param
 629          *
 630          * @param string $file
 631          * @param mixed $ext
 632          * @return bool|string
 633          * @throws UnexpectedValueException
 634          */
 635         private function doGuessMimeType( $file, $ext ) {
 636                 // Read a chunk of the file
 637                 Wikimedia\suppressWarnings();
 638                 $f = fopen( $file, 'rb' );
 639                 Wikimedia\restoreWarnings();
 640
 641                 if ( !$f ) {
 642                         return 'unknown/unknown';
 643                 }
 644
 645                 $fsize = filesize( $file );
 646                 if ( $fsize === false ) {
 647                         return 'unknown/unknown';
 648                 }
 649
 650                 $head = fread( $f, 1024 );
 651                 $tailLength = min( 65558, $fsize ); // 65558 = maximum size of a zip EOCDR
 652                 if ( fseek( $f, -1 * $tailLength, SEEK_END ) === -1 ) {
 653                         throw new UnexpectedValueException(
 654                                 "Seeking $tailLength bytes from EOF failed in " . __METHOD__ );
 655                 }
 656                 $tail = $tailLength ? fread( $f, $tailLength ) : '';
 657
 658                 $this->logger->info( __METHOD__ .
 659                         ": analyzing head and tail of $file for magic numbers.\n" );
 660
 661                 // Hardcode a few magic number checks...
 662                 $headers = [
 663                         // Multimedia...
 664                         'MThd'             => 'audio/midi',
 665                         'OggS'             => 'application/ogg',
 666                         'ID3'              => 'audio/mpeg',
 667                         "\xff\xfb"         => 'audio/mpeg', // MPEG-1 layer 3
 668                         "\xff\xf3"         => 'audio/mpeg', // MPEG-2 layer 3 (lower sample rates)
 669                         "\xff\xe3"         => 'audio/mpeg', // MPEG-2.5 layer 3 (very low sample rates)
 670
 671                         // Image formats...
 672                         // Note that WMF may have a bare header, no magic number.
 673                         "\x01\x00\x09\x00" => 'application/x-msmetafile', // Possibly prone to false positives?
 674                         "\xd7\xcd\xc6\x9a" => 'application/x-msmetafile',
 675                         '%PDF'             => 'application/pdf',
 676                         'gimp xcf'         => 'image/x-xcf',
 677
 678                         // Some forbidden fruit...
 679                         'MZ'               => 'application/octet-stream', // DOS/Windows executable
 680                         "\xca\xfe\xba\xbe" => 'application/octet-stream', // Mach-O binary
 681                         "\x7fELF"          => 'application/octet-stream', // ELF binary
 682                 ];
 683
 684                 foreach ( $headers as $magic => $candidate ) {
 685                         if ( strncmp( $head, $magic, strlen( $magic ) ) == 0 ) {
 686                                 $this->logger->info( __METHOD__ .
 687                                         ": magic header in $file recognized as $candidate\n" );
 688                                 return $candidate;
 689                         }
 690                 }
 691
 692                 /* Look for WebM and Matroska files */
 693                 if ( strncmp( $head, pack( "C4", 0x1a, 0x45, 0xdf, 0xa3 ), 4 ) == 0 ) {
 694                         $doctype = strpos( $head, "\x42\x82" );
 695                         if ( $doctype ) {
 696                                 // Next byte is datasize, then data (sizes larger than 1 byte are stupid muxers)
 697                                 $data = substr( $head, $doctype + 3, 8 );
 698                                 if ( strncmp( $data, "matroska", 8 ) == 0 ) {
 699                                         $this->logger->info( __METHOD__ . ": recognized file as video/x-matroska\n" );
 700                                         return "video/x-matroska";
 701                                 } elseif ( strncmp( $data, "webm", 4 ) == 0 ) {
 702                                         // XXX HACK look for a video track, if we don't find it, this is an audio file
 703                                         $videotrack = strpos( $head, "\x86\x85V_VP" );
 704
 705                                         if ( $videotrack ) {
 706                                                 // There is a video track, so this is a video file.
 707                                                 $this->logger->info( __METHOD__ . ": recognized file as video/webm\n" );
 708                                                 return "video/webm";
 709                                         }
 710
 711                                         $this->logger->info( __METHOD__ . ": recognized file as audio/webm\n" );
 712                                         return "audio/webm";
 713                                 }
 714                         }
 715                         $this->logger->info( __METHOD__ . ": unknown EBML file\n" );
 716                         return "unknown/unknown";
 717                 }
 718
 719                 /* Look for WebP */
 720                 if ( strncmp( $head, "RIFF", 4 ) == 0 &&
 721                         strncmp( substr( $head, 8, 7 ), "WEBPVP8", 7 ) == 0
 722                 ) {
 723                         $this->logger->info( __METHOD__ . ": recognized file as image/webp\n" );
 724                         return "image/webp";
 725                 }
 726
 727                 /* Look for MS Compound Binary (OLE) files */
 728                 if ( strncmp( $head, "\xd0\xcf\x11\xe0\xa1\xb1\x1a\xe1", 8 ) == 0 ) {
 729                         $this->logger->info( __METHOD__ . ': recognized MS CFB (OLE) file' );
 730                         return $this->detectMicrosoftBinaryType( $f );
 731                 }
 732
 733                 /**
 734                  * Look for PHP.  Check for this before HTML/XML...  Warning: this is a
 735                  * heuristic, and won't match a file with a lot of non-PHP before.  It
 736                  * will also match text files which could be PHP. :)
 737                  *
 738                  * @todo FIXME: For this reason, the check is probably useless -- an attacker
 739                  * could almost certainly just pad the file with a lot of nonsense to
 740                  * circumvent the check in any case where it would be a security
 741                  * problem.  On the other hand, it causes harmful false positives (bug
 742                  * 16583).  The heuristic has been cut down to exclude three-character
 743                  * strings like "<? ", but should it be axed completely?
 744                  */
 745                 if ( ( strpos( $head, '<?php' ) !== false ) ||
 746                         ( strpos( $head, "<\x00?\x00p\x00h\x00p" ) !== false ) ||
 747                         ( strpos( $head, "<\x00?\x00 " ) !== false ) ||
 748                         ( strpos( $head, "<\x00?\x00\n" ) !== false ) ||
 749                         ( strpos( $head, "<\x00?\x00\t" ) !== false ) ||
 750                         ( strpos( $head, "<\x00?\x00=" ) !== false )
 751                 ) {
 752                         $this->logger->info( __METHOD__ . ": recognized $file as application/x-php\n" );
 753                         return 'application/x-php';
 754                 }
 755
 756                 /**
 757                  * look for XML formats (XHTML and SVG)
 758                  */
 759                 Wikimedia\suppressWarnings();
 760                 $xml = new XmlTypeCheck( $file );
 761                 Wikimedia\restoreWarnings();
 762                 if ( $xml->wellFormed ) {
 763                         $xmlTypes = $this->xmlTypes;
 764                         return $xmlTypes[$xml->getRootElement()] ?? 'application/xml';
 765                 }
 766
 767                 /**
 768                  * look for shell scripts
 769                  */
 770                 $script_type = null;
 771
 772                 # detect by shebang
 773                 if ( substr( $head, 0, 2 ) == "#!" ) {
 774                         $script_type = "ASCII";
 775                 } elseif ( substr( $head, 0, 5 ) == "\xef\xbb\xbf#!" ) {
 776                         $script_type = "UTF-8";
 777                 } elseif ( substr( $head, 0, 7 ) == "\xfe\xff\x00#\x00!" ) {
 778                         $script_type = "UTF-16BE";
 779                 } elseif ( substr( $head, 0, 7 ) == "\xff\xfe#\x00!" ) {
 780                         $script_type = "UTF-16LE";
 781                 }
 782
 783                 if ( $script_type ) {
 784                         if ( $script_type !== "UTF-8" && $script_type !== "ASCII" ) {
 785                                 // Quick and dirty fold down to ASCII!
 786                                 $pack = [ 'UTF-16BE' => 'n*', 'UTF-16LE' => 'v*' ];
 787                                 $chars = unpack( $pack[$script_type], substr( $head, 2 ) );
 788                                 $head = '';
 789                                 foreach ( $chars as $codepoint ) {
 790                                         if ( $codepoint < 128 ) {
 791                                                 $head .= chr( $codepoint );
 792                                         } else {
 793                                                 $head .= '?';
 794                                         }
 795                                 }
 796                         }
 797
 798                         $match = [];
 799
 800                         if ( preg_match( '%/?([^\s]+/)(\w+)%', $head, $match ) ) {
 801                                 $mime = "application/x-{$match[2]}";
 802                                 $this->logger->info( __METHOD__ . ": shell script recognized as $mime\n" );
 803                                 return $mime;
 804                         }
 805                 }
 806
 807                 // Check for ZIP variants (before getimagesize)
 808                 $eocdrPos = strpos( $tail, "PK\x05\x06" );
 809                 if ( $eocdrPos !== false && $eocdrPos <= strlen( $tail ) - 22 ) {
 810                         $this->logger->info( __METHOD__ . ": ZIP signature present in $file\n" );
 811                         // Check if it really is a ZIP file, make sure the EOCDR is at the end (T40432)
 812                         $commentLength = unpack( "n", substr( $tail, $eocdrPos + 20 ) )[1];
 813                         if ( $eocdrPos + 22 + $commentLength !== strlen( $tail ) ) {
 814                                 $this->logger->info( __METHOD__ . ": ZIP EOCDR not at end. Not a ZIP file." );
 815                         } else {
 816                                 return $this->detectZipType( $head, $tail, $ext );
 817                         }
 818                 }
 819
 820                 // Check for STL (3D) files
 821                 // @see https://en.wikipedia.org/wiki/STL_(file_format)
 822                 if ( $fsize >= 15 &&
 823                         stripos( $head, 'SOLID ' ) === 0 &&
 824                         preg_match( '/\RENDSOLID .*$/i', $tail ) ) {
 825                         // ASCII STL file
 826                         return 'application/sla';
 827                 } elseif ( $fsize > 84 ) {
 828                         // binary STL file
 829                         $triangles = substr( $head, 80, 4 );
 830                         $triangles = unpack( 'V', $triangles );
 831                         $triangles = reset( $triangles );
 832                         if ( $triangles !== false && $fsize === 84 + ( $triangles * 50 ) ) {
 833                                 return 'application/sla';
 834                         }
 835                 }
 836
 837                 Wikimedia\suppressWarnings();
 838                 $gis = getimagesize( $file );
 839                 Wikimedia\restoreWarnings();
 840
 841                 if ( $gis && isset( $gis['mime'] ) ) {
 842                         $mime = $gis['mime'];
 843                         $this->logger->info( __METHOD__ . ": getimagesize detected $file as $mime\n" );
 844                         return $mime;
 845                 }
 846
 847                 # Media handling extensions can guess the MIME by content
 848                 # It's intentionally here so that if core is wrong about a type (false positive),
 849                 # people will hopefully nag and submit patches :)
 850                 $mime = false;
 851                 # Some strings by reference for performance - assuming well-behaved hooks
 852                 $callback = $this->guessCallback;
 853                 if ( $callback ) {
 854                         $callback( $this, $head, $tail, $file, $mime /* by reference */ );
 855                 }
 856
 857                 return $mime;
 858         }
 859
 860         /**
 861          * Detect application-specific file type of a given ZIP file from its
 862          * header data.  Currently works for OpenDocument and OpenXML types...
 863          * If can't tell, returns 'application/zip'.
 864          *
 865          * @param string $header Some reasonably-sized chunk of file header
 866          * @param string|null $tail The tail of the file
 867          * @param string|bool $ext The file extension, or true to extract it from the filename.
 868          *   Set it to false (default) to ignore the extension. DEPRECATED! Set to false,
 869          *   use improveTypeFromExtension($mime, $ext) later to improve MIME type.
 870          *
 871          * @return string
 872          */
 873         function detectZipType( $header, $tail = null, $ext = false ) {
 874                 if ( $ext ) { # TODO: remove $ext param
 875                         $this->logger->info( __METHOD__ .
 876                                 ": WARNING: use of the \$ext parameter is deprecated. " .
 877                                 "Use improveTypeFromExtension(\$mime, \$ext) instead.\n" );
 878                 }
 879
 880                 $mime = 'application/zip';
 881                 $opendocTypes = [
 882                         # In OASIS Open Document Format v1.2, Database front end document
 883                         # has a recommended MIME type of:
 884                         # application/vnd.oasis.opendocument.base
 885                         # Despite the type registered at the IANA being 'database' which is
 886                         # supposed to be normative.
 887                         # T35515
 888                         'base',
 889
 890                         'chart-template',
 891                         'chart',
 892                         'formula-template',
 893                         'formula',
 894                         'graphics-template',
 895                         'graphics',
 896                         'image-template',
 897                         'image',
 898                         'presentation-template',
 899                         'presentation',
 900                         'spreadsheet-template',
 901                         'spreadsheet',
 902                         'text-template',
 903                         'text-master',
 904                         'text-web',
 905                         'text' ];
 906
 907                 // The list of document types is available in OASIS Open Document
 908                 // Format version 1.2 under Appendix C. It is not normative though,
 909                 // supposedly types registered at the IANA should be.
 910                 // http://docs.oasis-open.org/office/v1.2/os/OpenDocument-v1.2-os-part1.html
 911                 $types = '(?:' . implode( '|', $opendocTypes ) . ')';
 912                 $opendocRegex = "/^mimetype(application\/vnd\.oasis\.opendocument\.$types)/";
 913
 914                 $openxmlRegex = "/^\[Content_Types\].xml/";
 915
 916                 if ( preg_match( $opendocRegex, substr( $header, 30 ), $matches ) ) {
 917                         $mime = $matches[1];
 918                         $this->logger->info( __METHOD__ . ": detected $mime from ZIP archive\n" );
 919                 } elseif ( preg_match( $openxmlRegex, substr( $header, 30 ) ) ) {
 920                         $mime = "application/x-opc+zip";
 921                         # TODO: remove the block below, as soon as improveTypeFromExtension is used everywhere
 922                         if ( $ext !== true && $ext !== false ) {
 923                                 /** This is the mode used by getPropsFromPath
 924                                  * These MIME's are stored in the database, where we don't really want
 925                                  * x-opc+zip, because we use it only for internal purposes
 926                                  */
 927                                 if ( $this->isMatchingExtension( $ext, $mime ) ) {
 928                                         /* A known file extension for an OPC file,
 929                                          * find the proper mime type for that file extension
 930                                          */
 931                                         $mime = $this->guessTypesForExtension( $ext );
 932                                 } else {
 933                                         $mime = "application/zip";
 934                                 }
 935                         }
 936                         $this->logger->info( __METHOD__ .
 937                                 ": detected an Open Packaging Conventions archive: $mime\n" );
 938                 } elseif ( substr( $header, 0, 8 ) == "\xd0\xcf\x11\xe0\xa1\xb1\x1a\xe1" &&
 939                         ( $headerpos = strpos( $tail, "PK\x03\x04" ) ) !== false &&
 940                         preg_match( $openxmlRegex, substr( $tail, $headerpos + 30 ) ) ) {
 941                         if ( substr( $header, 512, 4 ) == "\xEC\xA5\xC1\x00" ) {
 942                                 $mime = "application/msword";
 943                         }
 944                         switch ( substr( $header, 512, 6 ) ) {
 945                                 case "\xEC\xA5\xC1\x00\x0E\x00":
 946                                 case "\xEC\xA5\xC1\x00\x1C\x00":
 947                                 case "\xEC\xA5\xC1\x00\x43\x00":
 948                                         $mime = "application/vnd.ms-powerpoint";
 949                                         break;
 950                                 case "\xFD\xFF\xFF\xFF\x10\x00":
 951                                 case "\xFD\xFF\xFF\xFF\x1F\x00":
 952                                 case "\xFD\xFF\xFF\xFF\x22\x00":
 953                                 case "\xFD\xFF\xFF\xFF\x23\x00":
 954                                 case "\xFD\xFF\xFF\xFF\x28\x00":
 955                                 case "\xFD\xFF\xFF\xFF\x29\x00":
 956                                 case "\xFD\xFF\xFF\xFF\x10\x02":
 957                                 case "\xFD\xFF\xFF\xFF\x1F\x02":
 958                                 case "\xFD\xFF\xFF\xFF\x22\x02":
 959                                 case "\xFD\xFF\xFF\xFF\x23\x02":
 960                                 case "\xFD\xFF\xFF\xFF\x28\x02":
 961                                 case "\xFD\xFF\xFF\xFF\x29\x02":
 962                                         $mime = "application/vnd.msexcel";
 963                                         break;
 964                         }
 965
 966                         $this->logger->info( __METHOD__ .
 967                                 ": detected a MS Office document with OPC trailer\n" );
 968                 } else {
 969                         $this->logger->info( __METHOD__ . ": unable to identify type of ZIP archive\n" );
 970                 }
 971                 return $mime;
 972         }
 973
 974         /**
 975          * Detect the type of a Microsoft Compound Binary a.k.a. OLE file.
 976          * These are old style pre-ODF files such as .doc and .xls
 977          *
 978          * @param resource $handle An opened seekable file handle
 979          * @return string The detected MIME type
 980          */
 981         function detectMicrosoftBinaryType( $handle ) {
 982                 $info = MSCompoundFileReader::readHandle( $handle );
 983                 if ( !$info['valid'] ) {
 984                         $this->logger->info( __METHOD__ . ': invalid file format' );
 985                         return 'unknown/unknown';
 986                 }
 987                 if ( !$info['mime'] ) {
 988                         $this->logger->info( __METHOD__ . ": unrecognised document subtype" );
 989                         return 'unknown/unknown';
 990                 }
 991                 return $info['mime'];
 992         }
 993
 994         /**
 995          * Internal MIME type detection. Detection is done using the fileinfo
 996          * extension if it is available. It can be overriden by callback, which could
 997          * use an external program, for example. If detection fails and $ext is not false,
 998          * the MIME type is guessed from the file extension, using guessTypesForExtension.
 999          *
1000          * If the MIME type is still unknown, getimagesize is used to detect the
1001          * MIME type if the file is an image. If no MIME type can be determined,
1002          * this function returns 'unknown/unknown'.
1003          *
1004          * @param string $file The file to check
1005          * @param string|bool $ext The file extension, or true (default) to extract it from the filename.
1006          *   Set it to false to ignore the extension. DEPRECATED! Set to false, use
1007          *   improveTypeFromExtension($mime, $ext) later to improve MIME type.
1008          *
1009          * @return string The MIME type of $file
1010          */
1011         private function detectMimeType( $file, $ext = true ) {
1012                 /** @todo Make $ext default to false. Or better, remove it. */
1013                 if ( $ext ) {
1014                         $this->logger->info( __METHOD__ .
1015                                 ": WARNING: use of the \$ext parameter is deprecated. "
1016                                 . "Use improveTypeFromExtension(\$mime, \$ext) instead.\n" );
1017                 }
1018
1019                 $callback = $this->detectCallback;
1020                 $m = null;
1021                 if ( $callback ) {
1022                         $m = $callback( $file );
1023                 } else {
1024                         $m = mime_content_type( $file );
1025                 }
1026
1027                 if ( $m ) {
1028                         # normalize
1029                         $m = preg_replace( '![;, ].*$!', '', $m ); # strip charset, etc
1030                         $m = trim( $m );
1031                         $m = strtolower( $m );
1032
1033                         if ( strpos( $m, 'unknown' ) !== false ) {
1034                                 $m = null;
1035                         } else {
1036                                 $this->logger->info( __METHOD__ . ": magic mime type of $file: $m\n" );
1037                                 return $m;
1038                         }
1039                 }
1040
1041                 // If desired, look at extension as a fallback.
1042                 if ( $ext === true ) {
1043                         $i = strrpos( $file, '.' );
1044                         $ext = strtolower( $i ? substr( $file, $i + 1 ) : '' );
1045                 }
1046                 if ( $ext ) {
1047                         if ( $this->isRecognizableExtension( $ext ) ) {
1048                                 $this->logger->info( __METHOD__ . ": refusing to guess mime type for .$ext file, "
1049                                         . "we should have recognized it\n" );
1050                         } else {
1051                                 $m = $this->guessTypesForExtension( $ext );
1052                                 if ( $m ) {
1053                                         $this->logger->info( __METHOD__ . ": extension mime type of $file: $m\n" );
1054                                         return $m;
1055                                 }
1056                         }
1057                 }
1058
1059                 // Unknown type
1060                 $this->logger->info( __METHOD__ . ": failed to guess mime type for $file!\n" );
1061                 return 'unknown/unknown';
1062         }
1063
1064         /**
1065          * Determine the media type code for a file, using its MIME type, name and
1066          * possibly its contents.
1067          *
1068          * This function relies on the findMediaType(), mapping extensions and MIME
1069          * types to media types.
1070          *
1071          * @todo analyse file if need be
1072          * @todo look at multiple extension, separately and together.
1073          *
1074          * @param string|null $path Full path to the image file, in case we have to look at the contents
1075          *        (if null, only the MIME type is used to determine the media type code).
1076          * @param string|null $mime MIME type. If null it will be guessed using guessMimeType.
1077          *
1078          * @return string A value to be used with the MEDIATYPE_xxx constants.
1079          */
1080         function getMediaType( $path = null, $mime = null ) {
1081                 if ( !$mime && !$path ) {
1082                         return MEDIATYPE_UNKNOWN;
1083                 }
1084
1085                 // If MIME type is unknown, guess it
1086                 if ( !$mime ) {
1087                         $mime = $this->guessMimeType( $path, false );
1088                 }
1089
1090                 // Special code for ogg - detect if it's video (theora),
1091                 // else label it as sound.
1092                 if ( $mime == 'application/ogg' && is_string( $path ) && file_exists( $path ) ) {
1093                         // Read a chunk of the file
1094                         $f = fopen( $path, "rt" );
1095                         if ( !$f ) {
1096                                 return MEDIATYPE_UNKNOWN;
1097                         }
1098                         $head = fread( $f, 256 );
1099                         fclose( $f );
1100
1101                         $head = str_replace( 'ffmpeg2theora', '', strtolower( $head ) );
1102
1103                         // This is an UGLY HACK, file should be parsed correctly
1104                         if ( strpos( $head, 'theora' ) !== false ) {
1105                                 return MEDIATYPE_VIDEO;
1106                         } elseif ( strpos( $head, 'vorbis' ) !== false ) {
1107                                 return MEDIATYPE_AUDIO;
1108                         } elseif ( strpos( $head, 'flac' ) !== false ) {
1109                                 return MEDIATYPE_AUDIO;
1110                         } elseif ( strpos( $head, 'speex' ) !== false ) {
1111                                 return MEDIATYPE_AUDIO;
1112                         } elseif ( strpos( $head, 'opus' ) !== false ) {
1113                                 return MEDIATYPE_AUDIO;
1114                         } else {
1115                                 return MEDIATYPE_MULTIMEDIA;
1116                         }
1117                 }
1118
1119                 $type = null;
1120                 // Check for entry for full MIME type
1121                 if ( $mime ) {
1122                         $type = $this->findMediaType( $mime );
1123                         if ( $type !== MEDIATYPE_UNKNOWN ) {
1124                                 return $type;
1125                         }
1126                 }
1127
1128                 // Check for entry for file extension
1129                 if ( $path ) {
1130                         $i = strrpos( $path, '.' );
1131                         $e = strtolower( $i ? substr( $path, $i + 1 ) : '' );
1132
1133                         // TODO: look at multi-extension if this fails, parse from full path
1134                         $type = $this->findMediaType( '.' . $e );
1135                         if ( $type !== MEDIATYPE_UNKNOWN ) {
1136                                 return $type;
1137                         }
1138                 }
1139
1140                 // Check major MIME type
1141                 if ( $mime ) {
1142                         $i = strpos( $mime, '/' );
1143                         if ( $i !== false ) {
1144                                 $major = substr( $mime, 0, $i );
1145                                 $type = $this->findMediaType( $major );
1146                                 if ( $type !== MEDIATYPE_UNKNOWN ) {
1147                                         return $type;
1148                                 }
1149                         }
1150                 }
1151
1152                 if ( !$type ) {
1153                         $type = MEDIATYPE_UNKNOWN;
1154                 }
1155
1156                 return $type;
1157         }
1158
1159         /**
1160          * Returns a media code matching the given MIME type or file extension.
1161          * File extensions are represented by a string starting with a dot (.) to
1162          * distinguish them from MIME types.
1163          *
1164          * This function relies on the mapping defined by $this->mMediaTypes
1165          * @private
1166          * @param string $extMime
1167          * @return int|string
1168          */
1169         function findMediaType( $extMime ) {
1170                 if ( strpos( $extMime, '.' ) === 0 ) {
1171                         // If it's an extension, look up the MIME types
1172                         $m = $this->getTypesForExtension( substr( $extMime, 1 ) );
1173                         if ( !$m ) {
1174                                 return MEDIATYPE_UNKNOWN;
1175                         }
1176
1177                         $m = explode( ' ', $m );
1178                 } else {
1179                         // Normalize MIME type
1180                         if ( isset( $this->mimeTypeAliases[$extMime] ) ) {
1181                                 $extMime = $this->mimeTypeAliases[$extMime];
1182                         }
1183
1184                         $m = [ $extMime ];
1185                 }
1186
1187                 foreach ( $m as $mime ) {
1188                         foreach ( $this->mediaTypes as $type => $codes ) {
1189                                 if ( in_array( $mime, $codes, true ) ) {
1190                                         return $type;
1191                                 }
1192                         }
1193                 }
1194
1195                 return MEDIATYPE_UNKNOWN;
1196         }
1197
1198         /**
1199          * Returns an array of media types (MEDIATYPE_xxx constants)
1200          *
1201          * @return array
1202          */
1203         public function getMediaTypes() {
1204                 return array_keys( $this->mediaTypes );
1205         }
1206
1207         /**
1208          * Get the MIME types that various versions of Internet Explorer would
1209          * detect from a chunk of the content.
1210          *
1211          * @param string $fileName The file name (unused at present)
1212          * @param string $chunk The first 256 bytes of the file
1213          * @param string $proposed The MIME type proposed by the server
1214          * @return array
1215          */
1216         public function getIEMimeTypes( $fileName, $chunk, $proposed ) {
1217                 $ca = $this->getIEContentAnalyzer();
1218                 return $ca->getRealMimesFromData( $fileName, $chunk, $proposed );
1219         }
1220
1221         /**
1222          * Get a cached instance of IEContentAnalyzer
1223          *
1224          * @return IEContentAnalyzer
1225          */
1226         protected function getIEContentAnalyzer() {
1227                 if ( is_null( $this->IEAnalyzer ) ) {
1228                         $this->IEAnalyzer = new IEContentAnalyzer;
1229                 }
1230                 return $this->IEAnalyzer;
1231         }
1232 }