MimeAnalyzer.php

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<?php
use Psr\Log\LoggerAwareInterface;
use Psr\Log\LoggerInterface;
use Psr\Log\NullLogger;
use Wikimedia\Mime\MimeMap;
use Wikimedia\Mime\MimeMapMinimal;
 
class MimeAnalyzer implements LoggerAwareInterface {
    protected $typeFile;
    protected $infoFile;
    protected $xmlTypes;
    protected $initCallback;
    protected $detectCallback;
    protected $guessCallback;
    protected $extCallback;
    protected $mediaTypes = null;
    protected $mimeTypeAliases = null;
    protected $mimeToExts = [];
    protected $extToMimes = [];
 
    public $mExtToMime = []; // legacy name; field accessed by hooks
 
    protected $IEAnalyzer;
 
    private $extraTypes = '';
    private $extraInfo = '';
 
    private $logger;
 
    public const USE_INTERNAL = 'internal';
 
    public function __construct( array $params ) {
        $this->typeFile = $params['typeFile'];
        $this->infoFile = $params['infoFile'];
        $this->xmlTypes = $params['xmlTypes'];
        $this->initCallback = $params['initCallback'] ?? null;
        $this->detectCallback = $params['detectCallback'] ?? null;
        $this->guessCallback = $params['guessCallback'] ?? null;
        $this->extCallback = $params['extCallback'] ?? null;
        $this->logger = $params['logger'] ?? new NullLogger();
 
        $this->loadFiles();
    }
 
    protected function loadFiles() {
        # Allow media handling extensions adding MIME-types and MIME-info
        if ( $this->initCallback ) {
            call_user_func( $this->initCallback, $this );
        }
 
        $rawTypes = $this->extraTypes;
        if ( $this->typeFile === self::USE_INTERNAL ) {
            $this->mimeToExts = MimeMap::MIME_EXTENSIONS;
        } else {
            $this->mimeToExts = MimeMapMinimal::MIME_EXTENSIONS;
            if ( $this->typeFile ) {
                $rawTypes = file_get_contents( $this->typeFile ) . "\n" . $this->extraTypes;
            }
        }
        if ( $rawTypes ) {
            $this->parseMimeTypes( $rawTypes );
        }
 
        // Build the reverse mapping (extension => MIME type).
        foreach ( $this->mimeToExts as $mime => $exts ) {
            foreach ( $exts as $ext ) {
                $this->extToMimes[$ext][] = $mime;
            }
        }
 
        // Migrate items from the legacy $this->mExtToMime field.
        // TODO: Remove this when mExtToMime is finally removed.
        foreach ( $this->mExtToMime as $ext => $mimes ) {
            foreach ( explode( ' ', $mimes ) as $mime ) {
                $this->extToMimes[$ext][] = $mime;
            }
        }
 
        $rawInfo = $this->extraInfo;
        if ( $this->infoFile === self::USE_INTERNAL ) {
            $this->mimeTypeAliases = MimeMap::MIME_TYPE_ALIASES;
            $this->mediaTypes = MimeMap::MEDIA_TYPES;
        } else {
            $this->mimeTypeAliases = MimeMapMinimal::MIME_TYPE_ALIASES;
            $this->mediaTypes = MimeMapMinimal::MEDIA_TYPES;
            if ( $this->infoFile ) {
                $rawInfo = file_get_contents( $this->infoFile ) . "\n" . $this->extraInfo;
            }
        }
        if ( $rawInfo ) {
            $this->parseMimeInfo( $rawInfo );
        }
    }
 
    protected function parseMimeTypes( $rawMimeTypes ) {
        $rawMimeTypes = str_replace( [ "\r\n", "\n\r", "\n\n", "\r\r", "\r" ], "\n", $rawMimeTypes );
        $rawMimeTypes = str_replace( "\t", " ", $rawMimeTypes );
 
        $lines = explode( "\n", $rawMimeTypes );
        foreach ( $lines as $s ) {
            $s = trim( $s );
            if ( empty( $s ) ) {
                continue;
            }
            if ( strpos( $s, '#' ) === 0 ) {
                continue;
            }
 
            $s = strtolower( $s );
            $i = strpos( $s, ' ' );
 
            if ( $i === false ) {
                continue;
            }
 
            $mime = substr( $s, 0, $i );
            $ext = trim( substr( $s, $i + 1 ) );
 
            if ( empty( $ext ) ) {
                continue;
            }
 
            $tokens = preg_split( '/\s+/', $s, -1, PREG_SPLIT_NO_EMPTY );
            if ( count( $tokens ) > 1 ) {
                $mime = array_shift( $tokens );
                $this->mimeToExts[$mime] = array_values( array_unique(
                    array_merge( $this->mimeToExts[$mime] ?? [], $tokens ) ) );
            }
        }
    }
 
    protected function parseMimeInfo( $rawMimeInfo ) {
        $rawMimeInfo = str_replace( [ "\r\n", "\n\r", "\n\n", "\r\r", "\r" ], "\n", $rawMimeInfo );
        $rawMimeInfo = str_replace( "\t", " ", $rawMimeInfo );
 
        $lines = explode( "\n", $rawMimeInfo );
        foreach ( $lines as $s ) {
            $s = trim( $s );
            if ( empty( $s ) ) {
                continue;
            }
            if ( strpos( $s, '#' ) === 0 ) {
                continue;
            }
 
            $s = strtolower( $s );
            $i = strpos( $s, ' ' );
 
            if ( $i === false ) {
                continue;
            }
 
            # print "processing MIME INFO line $s<br>";
 
            $match = [];
            if ( preg_match( '!\[\s*(\w+)\s*\]!', $s, $match ) ) {
                $s = preg_replace( '!\[\s*(\w+)\s*\]!', '', $s );
                $mtype = trim( strtoupper( $match[1] ) );
            } else {
                $mtype = MEDIATYPE_UNKNOWN;
            }
 
            $m = preg_split( '/\s+/', $s, -1, PREG_SPLIT_NO_EMPTY );
 
            if ( !isset( $this->mediaTypes[$mtype] ) ) {
                $this->mediaTypes[$mtype] = [];
            }
 
            foreach ( $m as $mime ) {
                $mime = trim( $mime );
                if ( empty( $mime ) ) {
                    continue;
                }
 
                $this->mediaTypes[$mtype][] = $mime;
            }
 
            if ( count( $m ) > 1 ) {
                $main = $m[0];
                $mCount = count( $m );
                for ( $i = 1; $i < $mCount; $i += 1 ) {
                    $mime = $m[$i];
                    $this->mimeTypeAliases[$mime] = $main;
                }
            }
        }
    }
 
    public function setLogger( LoggerInterface $logger ) {
        $this->logger = $logger;
    }
 
    public function addExtraTypes( $types ) {
        $this->extraTypes .= "\n" . $types;
    }
 
    public function addExtraInfo( $info ) {
        $this->extraInfo .= "\n" . $info;
    }
 
    public function getExtensionsForType( $mime ) {
        $exts = $this->getExtensionsFromMimeType( $mime );
        return $exts ? implode( ' ', $exts ) : null;
    }
 
    public function getExtensionsFromMimeType( $mime ) {
        $mime = strtolower( $mime );
        if ( !isset( $this->mimeToExts[$mime] ) && isset( $this->mimeTypeAliases[$mime] ) ) {
            $mime = $this->mimeTypeAliases[$mime];
        }
        return $this->mimeToExts[$mime] ?? [];
    }
 
    public function getMimeTypesFromExtension( $ext ) {
        $ext = strtolower( $ext );
        return $this->extToMimes[$ext] ?? [];
    }
 
    public function getMimeTypeFromExtensionOrNull( $ext ) {
        $types = $this->getMimeTypesFromExtension( $ext );
        return $types[0] ?? null;
    }
 
    public function guessTypesForExtension( $ext ) {
        return $this->getMimeTypeFromExtensionOrNull( $ext );
    }
 
    public function getTypesForExtension( $ext ) {
        $types = $this->getMimeTypesFromExtension( $ext );
        return $types ? implode( ' ', $types ) : null;
    }
 
    public function getExtensionFromMimeTypeOrNull( $mime ) {
        $exts = $this->getExtensionsFromMimeType( $mime );
        return $exts[0] ?? null;
    }
 
    public function isMatchingExtension( $extension, $mime ) {
        $exts = $this->getExtensionsFromMimeType( $mime );
 
        if ( !$exts ) {
            return null; // Unknown MIME type
        }
 
        return in_array( strtolower( $extension ), $exts );
    }
 
    public function isPHPImageType( $mime ) {
        // As defined by imagegetsize and image_type_to_mime
        static $types = [
            'image/gif', 'image/jpeg', 'image/png',
            'image/x-bmp', 'image/xbm', 'image/tiff',
            'image/jp2', 'image/jpeg2000', 'image/iff',
            'image/xbm', 'image/x-xbitmap',
            'image/vnd.wap.wbmp', 'image/vnd.xiff',
            'image/x-photoshop',
            'application/x-shockwave-flash',
        ];
 
        return in_array( $mime, $types );
    }
 
    public function isRecognizableExtension( $extension ) {
        static $types = [
            // Types recognized by getimagesize()
            'gif', 'jpeg', 'jpg', 'png', 'swf', 'psd',
            'bmp', 'tiff', 'tif', 'jpc', 'jp2',
            'jpx', 'jb2', 'swc', 'iff', 'wbmp',
            'xbm',
 
            // Formats we recognize magic numbers for
            'djvu', 'ogx', 'ogg', 'ogv', 'oga', 'spx', 'opus',
            'mid', 'pdf', 'wmf', 'xcf', 'webm', 'mkv', 'mka',
            'webp', 'mp3',
 
            // XML formats we sure hope we recognize reliably
            'svg',
 
            // 3D formats
            'stl',
        ];
        return in_array( strtolower( $extension ), $types );
    }
 
    public function improveTypeFromExtension( $mime, $ext ) {
        if ( $mime === 'unknown/unknown' ) {
            if ( $this->isRecognizableExtension( $ext ) ) {
                $this->logger->info( __METHOD__ . ': refusing to guess mime type for .' .
                    "$ext file, we should have recognized it\n" );
            } else {
                // Not something we can detect, so simply
                // trust the file extension
                $mime = $this->getMimeTypeFromExtensionOrNull( $ext );
            }
        } elseif ( $mime === 'application/x-opc+zip' ) {
            if ( $this->isMatchingExtension( $ext, $mime ) ) {
                // A known file extension for an OPC file,
                // find the proper MIME type for that file extension
                $mime = $this->getMimeTypeFromExtensionOrNull( $ext );
            } else {
                $this->logger->info( __METHOD__ .
                    ": refusing to guess better type for $mime file, " .
                    ".$ext is not a known OPC extension.\n" );
                $mime = 'application/zip';
            }
        } elseif ( $mime === 'text/plain' && $this->findMediaType( ".$ext" ) === MEDIATYPE_TEXT ) {
            // Textual types are sometimes not recognized properly.
            // If detected as text/plain, and has an extension which is textual
            // improve to the extension's type. For example, csv and json are often
            // misdetected as text/plain.
            $mime = $this->getMimeTypeFromExtensionOrNull( $ext );
        }
 
        # Media handling extensions can improve the MIME detected
        $callback = $this->extCallback;
        if ( $callback ) {
            $callback( $this, $ext, $mime /* by reference */ );
        }
 
        if ( isset( $this->mimeTypeAliases[$mime] ) ) {
            $mime = $this->mimeTypeAliases[$mime];
        }
 
        $this->logger->info( __METHOD__ . ": improved mime type for .$ext: $mime\n" );
        return $mime;
    }
 
    public function guessMimeType( $file, $ext = true ) {
        if ( $ext ) { // TODO: make $ext default to false. Or better, remove it.
            $this->logger->info( __METHOD__ .
                ": WARNING: use of the \$ext parameter is deprecated. " .
                "Use improveTypeFromExtension(\$mime, \$ext) instead.\n" );
        }
 
        $mime = $this->doGuessMimeType( $file, $ext );
 
        if ( !$mime ) {
            $this->logger->info( __METHOD__ .
                ": internal type detection failed for $file (.$ext)...\n" );
            $mime = $this->detectMimeType( $file, $ext );
        }
 
        if ( isset( $this->mimeTypeAliases[$mime] ) ) {
            $mime = $this->mimeTypeAliases[$mime];
        }
 
        $this->logger->info( __METHOD__ . ": guessed mime type of $file: $mime\n" );
        return $mime;
    }
 
    private function doGuessMimeType( $file, $ext ) {
        // Read a chunk of the file
        Wikimedia\suppressWarnings();
        $f = fopen( $file, 'rb' );
        Wikimedia\restoreWarnings();
 
        if ( !$f ) {
            return 'unknown/unknown';
        }
 
        $fsize = filesize( $file );
        if ( $fsize === false ) {
            return 'unknown/unknown';
        }
 
        $head = fread( $f, 1024 );
        $tailLength = min( 65558, $fsize ); // 65558 = maximum size of a zip EOCDR
        if ( fseek( $f, -1 * $tailLength, SEEK_END ) === -1 ) {
            throw new UnexpectedValueException(
                "Seeking $tailLength bytes from EOF failed in " . __METHOD__ );
        }
        $tail = $tailLength ? fread( $f, $tailLength ) : '';
 
        $this->logger->info( __METHOD__ .
            ": analyzing head and tail of $file for magic numbers.\n" );
 
        // Hardcode a few magic number checks...
        $headers = [
            // Multimedia...
            'MThd'             => 'audio/midi',
            'OggS'             => 'application/ogg',
            'ID3'              => 'audio/mpeg',
            "\xff\xfb"         => 'audio/mpeg', // MPEG-1 layer 3
            "\xff\xf3"         => 'audio/mpeg', // MPEG-2 layer 3 (lower sample rates)
            "\xff\xe3"         => 'audio/mpeg', // MPEG-2.5 layer 3 (very low sample rates)
 
            // Image formats...
            // Note that WMF may have a bare header, no magic number.
            "\x01\x00\x09\x00" => 'application/x-msmetafile', // Possibly prone to false positives?
            "\xd7\xcd\xc6\x9a" => 'application/x-msmetafile',
            '%PDF'             => 'application/pdf',
            'gimp xcf'         => 'image/x-xcf',
 
            // Some forbidden fruit...
            'MZ'               => 'application/octet-stream', // DOS/Windows executable
            "\xca\xfe\xba\xbe" => 'application/octet-stream', // Mach-O binary
            "\x7fELF"          => 'application/octet-stream', // ELF binary
        ];
 
        foreach ( $headers as $magic => $candidate ) {
            if ( strncmp( $head, $magic, strlen( $magic ) ) == 0 ) {
                $this->logger->info( __METHOD__ .
                    ": magic header in $file recognized as $candidate\n" );
                return $candidate;
            }
        }
 
        /* Look for WebM and Matroska files */
        if ( strncmp( $head, pack( "C4", 0x1a, 0x45, 0xdf, 0xa3 ), 4 ) == 0 ) {
            $doctype = strpos( $head, "\x42\x82" );
            if ( $doctype ) {
                // Next byte is datasize, then data (sizes larger than 1 byte are stupid muxers)
                $data = substr( $head, $doctype + 3, 8 );
                if ( strncmp( $data, "matroska", 8 ) == 0 ) {
                    $this->logger->info( __METHOD__ . ": recognized file as video/x-matroska\n" );
                    return "video/x-matroska";
                } elseif ( strncmp( $data, "webm", 4 ) == 0 ) {
                    // XXX HACK look for a video track, if we don't find it, this is an audio file
                    $videotrack = strpos( $head, "\x86\x85V_VP" );
 
                    if ( $videotrack ) {
                        // There is a video track, so this is a video file.
                        $this->logger->info( __METHOD__ . ": recognized file as video/webm\n" );
                        return "video/webm";
                    }
 
                    $this->logger->info( __METHOD__ . ": recognized file as audio/webm\n" );
                    return "audio/webm";
                }
            }
            $this->logger->info( __METHOD__ . ": unknown EBML file\n" );
            return "unknown/unknown";
        }
 
        /* Look for WebP */
        if ( strncmp( $head, "RIFF", 4 ) == 0 &&
            strncmp( substr( $head, 8, 7 ), "WEBPVP8", 7 ) == 0
        ) {
            $this->logger->info( __METHOD__ . ": recognized file as image/webp\n" );
            return "image/webp";
        }
 
        /* Look for MS Compound Binary (OLE) files */
        if ( strncmp( $head, "\xd0\xcf\x11\xe0\xa1\xb1\x1a\xe1", 8 ) == 0 ) {
            $this->logger->info( __METHOD__ . ': recognized MS CFB (OLE) file' );
            return $this->detectMicrosoftBinaryType( $f );
        }
 
        if ( ( strpos( $head, '<?php' ) !== false ) ||
            ( strpos( $head, "<\x00?\x00p\x00h\x00p" ) !== false ) ||
            ( strpos( $head, "<\x00?\x00 " ) !== false ) ||
            ( strpos( $head, "<\x00?\x00\n" ) !== false ) ||
            ( strpos( $head, "<\x00?\x00\t" ) !== false ) ||
            ( strpos( $head, "<\x00?\x00=" ) !== false )
        ) {
            $this->logger->info( __METHOD__ . ": recognized $file as application/x-php\n" );
            return 'application/x-php';
        }
 
        Wikimedia\suppressWarnings();
        $xml = new XmlTypeCheck( $file );
        Wikimedia\restoreWarnings();
        if ( $xml->wellFormed ) {
            $xmlTypes = $this->xmlTypes;
            return $xmlTypes[$xml->getRootElement()] ?? 'application/xml';
        }
 
        $script_type = null;
 
        # detect by shebang
        if ( substr( $head, 0, 2 ) == "#!" ) {
            $script_type = "ASCII";
        } elseif ( substr( $head, 0, 5 ) == "\xef\xbb\xbf#!" ) {
            $script_type = "UTF-8";
        } elseif ( substr( $head, 0, 7 ) == "\xfe\xff\x00#\x00!" ) {
            $script_type = "UTF-16BE";
        } elseif ( substr( $head, 0, 7 ) == "\xff\xfe#\x00!" ) {
            $script_type = "UTF-16LE";
        }
 
        if ( $script_type ) {
            if ( $script_type !== "UTF-8" && $script_type !== "ASCII" ) {
                // Quick and dirty fold down to ASCII!
                $pack = [ 'UTF-16BE' => 'n*', 'UTF-16LE' => 'v*' ];
                $chars = unpack( $pack[$script_type], substr( $head, 2 ) );
                $head = '';
                foreach ( $chars as $codepoint ) {
                    if ( $codepoint < 128 ) {
                        $head .= chr( $codepoint );
                    } else {
                        $head .= '?';
                    }
                }
            }
 
            $match = [];
 
            if ( preg_match( '%/?([^\s]+/)(\w+)%', $head, $match ) ) {
                $mime = "application/x-{$match[2]}";
                $this->logger->info( __METHOD__ . ": shell script recognized as $mime\n" );
                return $mime;
            }
        }
 
        // Check for ZIP variants (before getimagesize)
        $eocdrPos = strpos( $tail, "PK\x05\x06" );
        if ( $eocdrPos !== false && $eocdrPos <= strlen( $tail ) - 22 ) {
            $this->logger->info( __METHOD__ . ": ZIP signature present in $file\n" );
            // Check if it really is a ZIP file, make sure the EOCDR is at the end (T40432)
            $commentLength = unpack( "n", substr( $tail, $eocdrPos + 20 ) )[1];
            if ( $eocdrPos + 22 + $commentLength !== strlen( $tail ) ) {
                $this->logger->info( __METHOD__ . ": ZIP EOCDR not at end. Not a ZIP file." );
            } else {
                return $this->detectZipType( $head, $tail, $ext );
            }
        }
 
        // Check for STL (3D) files
        // @see https://en.wikipedia.org/wiki/STL_(file_format)
        if ( $fsize >= 15 &&
            stripos( $head, 'SOLID ' ) === 0 &&
            preg_match( '/\RENDSOLID .*$/i', $tail ) ) {
            // ASCII STL file
            return 'application/sla';
        } elseif ( $fsize > 84 ) {
            // binary STL file
            $triangles = substr( $head, 80, 4 );
            $triangles = unpack( 'V', $triangles );
            $triangles = reset( $triangles );
            if ( $triangles !== false && $fsize === 84 + ( $triangles * 50 ) ) {
                return 'application/sla';
            }
        }
 
        Wikimedia\suppressWarnings();
        $gis = getimagesize( $file );
        Wikimedia\restoreWarnings();
 
        if ( $gis && isset( $gis['mime'] ) ) {
            $mime = $gis['mime'];
            $this->logger->info( __METHOD__ . ": getimagesize detected $file as $mime\n" );
            return $mime;
        }
 
        # Media handling extensions can guess the MIME by content
        # It's intentionally here so that if core is wrong about a type (false positive),
        # people will hopefully nag and submit patches :)
        $mime = false;
        # Some strings by reference for performance - assuming well-behaved hooks
        $callback = $this->guessCallback;
        if ( $callback ) {
            $callback( $this, $head, $tail, $file, $mime /* by reference */ );
        }
 
        return $mime;
    }
 
    public function detectZipType( $header, $tail = null, $ext = false ) {
        if ( $ext ) { # TODO: remove $ext param
            $this->logger->info( __METHOD__ .
                ": WARNING: use of the \$ext parameter is deprecated. " .
                "Use improveTypeFromExtension(\$mime, \$ext) instead.\n" );
        }
 
        $mime = 'application/zip';
        $opendocTypes = [
            # In OASIS Open Document Format v1.2, Database front end document
            # has a recommended MIME type of:
            # application/vnd.oasis.opendocument.base
            # Despite the type registered at the IANA being 'database' which is
            # supposed to be normative.
            # T35515
            'base',
 
            'chart-template',
            'chart',
            'formula-template',
            'formula',
            'graphics-template',
            'graphics',
            'image-template',
            'image',
            'presentation-template',
            'presentation',
            'spreadsheet-template',
            'spreadsheet',
            'text-template',
            'text-master',
            'text-web',
            'text' ];
 
        // The list of document types is available in OASIS Open Document
        // Format version 1.2 under Appendix C. It is not normative though,
        // supposedly types registered at the IANA should be.
        // http://docs.oasis-open.org/office/v1.2/os/OpenDocument-v1.2-os-part1.html
        $types = '(?:' . implode( '|', $opendocTypes ) . ')';
        $opendocRegex = "/^mimetype(application\/vnd\.oasis\.opendocument\.$types)/";
 
        $openxmlRegex = "/^\[Content_Types\].xml/";
 
        if ( preg_match( $opendocRegex, substr( $header, 30 ), $matches ) ) {
            $mime = $matches[1];
            $this->logger->info( __METHOD__ . ": detected $mime from ZIP archive\n" );
        } elseif ( preg_match( $openxmlRegex, substr( $header, 30 ) ) ) {
            $mime = "application/x-opc+zip";
            # TODO: remove the block below, as soon as improveTypeFromExtension is used everywhere
            if ( $ext !== true && $ext !== false ) {
                if ( $this->isMatchingExtension( $ext, $mime ) ) {
                    /* A known file extension for an OPC file,
                     * find the proper mime type for that file extension
                     */
                    $mime = $this->getMimeTypeFromExtensionOrNull( $ext );
                } else {
                    $mime = "application/zip";
                }
            }
            $this->logger->info( __METHOD__ .
                ": detected an Open Packaging Conventions archive: $mime\n" );
        } elseif ( substr( $header, 0, 8 ) == "\xd0\xcf\x11\xe0\xa1\xb1\x1a\xe1" &&
            ( $headerpos = strpos( $tail, "PK\x03\x04" ) ) !== false &&
            preg_match( $openxmlRegex, substr( $tail, $headerpos + 30 ) ) ) {
            if ( substr( $header, 512, 4 ) == "\xEC\xA5\xC1\x00" ) {
                $mime = "application/msword";
            }
            switch ( substr( $header, 512, 6 ) ) {
                case "\xEC\xA5\xC1\x00\x0E\x00":
                case "\xEC\xA5\xC1\x00\x1C\x00":
                case "\xEC\xA5\xC1\x00\x43\x00":
                    $mime = "application/vnd.ms-powerpoint";
                    break;
                case "\xFD\xFF\xFF\xFF\x10\x00":
                case "\xFD\xFF\xFF\xFF\x1F\x00":
                case "\xFD\xFF\xFF\xFF\x22\x00":
                case "\xFD\xFF\xFF\xFF\x23\x00":
                case "\xFD\xFF\xFF\xFF\x28\x00":
                case "\xFD\xFF\xFF\xFF\x29\x00":
                case "\xFD\xFF\xFF\xFF\x10\x02":
                case "\xFD\xFF\xFF\xFF\x1F\x02":
                case "\xFD\xFF\xFF\xFF\x22\x02":
                case "\xFD\xFF\xFF\xFF\x23\x02":
                case "\xFD\xFF\xFF\xFF\x28\x02":
                case "\xFD\xFF\xFF\xFF\x29\x02":
                    $mime = "application/vnd.msexcel";
                    break;
            }
 
            $this->logger->info( __METHOD__ .
                ": detected a MS Office document with OPC trailer\n" );
        } else {
            $this->logger->info( __METHOD__ . ": unable to identify type of ZIP archive\n" );
        }
        return $mime;
    }
 
    private function detectMicrosoftBinaryType( $handle ) {
        $info = MSCompoundFileReader::readHandle( $handle );
        if ( !$info['valid'] ) {
            $this->logger->info( __METHOD__ . ': invalid file format' );
            return 'unknown/unknown';
        }
        if ( !$info['mime'] ) {
            $this->logger->info( __METHOD__ . ": unrecognised document subtype" );
            return 'unknown/unknown';
        }
        return $info['mime'];
    }
 
    private function detectMimeType( $file, $ext = true ) {
        if ( $ext ) {
            $this->logger->info( __METHOD__ .
                ": WARNING: use of the \$ext parameter is deprecated. "
                . "Use improveTypeFromExtension(\$mime, \$ext) instead.\n" );
        }
 
        $callback = $this->detectCallback;
        $m = null;
        if ( $callback ) {
            $m = $callback( $file );
        } else {
            $m = mime_content_type( $file );
        }
 
        if ( $m ) {
            # normalize
            $m = preg_replace( '![;, ].*$!', '', $m ); # strip charset, etc
            $m = trim( $m );
            $m = strtolower( $m );
 
            if ( strpos( $m, 'unknown' ) !== false ) {
                $m = null;
            } else {
                $this->logger->info( __METHOD__ . ": magic mime type of $file: $m\n" );
                return $m;
            }
        }
 
        // If desired, look at extension as a fallback.
        if ( $ext === true ) {
            $i = strrpos( $file, '.' );
            $ext = strtolower( $i ? substr( $file, $i + 1 ) : '' );
        }
        if ( $ext ) {
            if ( $this->isRecognizableExtension( $ext ) ) {
                $this->logger->info( __METHOD__ . ": refusing to guess mime type for .$ext file, "
                    . "we should have recognized it\n" );
            } else {
                $m = $this->getMimeTypeFromExtensionOrNull( $ext );
                if ( $m ) {
                    $this->logger->info( __METHOD__ . ": extension mime type of $file: $m\n" );
                    return $m;
                }
            }
        }
 
        // Unknown type
        $this->logger->info( __METHOD__ . ": failed to guess mime type for $file!\n" );
        return 'unknown/unknown';
    }
 
    public function getMediaType( $path = null, $mime = null ) {
        if ( !$mime && !$path ) {
            return MEDIATYPE_UNKNOWN;
        }
 
        // If MIME type is unknown, guess it
        if ( !$mime ) {
            $mime = $this->guessMimeType( $path, false );
        }
 
        // Special code for ogg - detect if it's video (theora),
        // else label it as sound.
        if ( $mime == 'application/ogg' && is_string( $path ) && file_exists( $path ) ) {
            // Read a chunk of the file
            $f = fopen( $path, "rt" );
            if ( !$f ) {
                return MEDIATYPE_UNKNOWN;
            }
            $head = fread( $f, 256 );
            fclose( $f );
 
            $head = str_replace( 'ffmpeg2theora', '', strtolower( $head ) );
 
            // This is an UGLY HACK, file should be parsed correctly
            if ( strpos( $head, 'theora' ) !== false ) {
                return MEDIATYPE_VIDEO;
            } elseif ( strpos( $head, 'vorbis' ) !== false ) {
                return MEDIATYPE_AUDIO;
            } elseif ( strpos( $head, 'flac' ) !== false ) {
                return MEDIATYPE_AUDIO;
            } elseif ( strpos( $head, 'speex' ) !== false ) {
                return MEDIATYPE_AUDIO;
            } elseif ( strpos( $head, 'opus' ) !== false ) {
                return MEDIATYPE_AUDIO;
            } else {
                return MEDIATYPE_MULTIMEDIA;
            }
        }
 
        $type = null;
        // Check for entry for full MIME type
        if ( $mime ) {
            $type = $this->findMediaType( $mime );
            if ( $type !== MEDIATYPE_UNKNOWN ) {
                return $type;
            }
        }
 
        // Check for entry for file extension
        if ( $path ) {
            $i = strrpos( $path, '.' );
            $e = strtolower( $i ? substr( $path, $i + 1 ) : '' );
 
            // TODO: look at multi-extension if this fails, parse from full path
            $type = $this->findMediaType( '.' . $e );
            if ( $type !== MEDIATYPE_UNKNOWN ) {
                return $type;
            }
        }
 
        // Check major MIME type
        if ( $mime ) {
            $i = strpos( $mime, '/' );
            if ( $i !== false ) {
                $major = substr( $mime, 0, $i );
                $type = $this->findMediaType( $major );
                if ( $type !== MEDIATYPE_UNKNOWN ) {
                    return $type;
                }
            }
        }
 
        if ( !$type ) {
            $type = MEDIATYPE_UNKNOWN;
        }
 
        return $type;
    }
 
    public function findMediaType( $extMime ) {
        if ( strpos( $extMime, '.' ) === 0 ) {
            // If it's an extension, look up the MIME types
            $m = $this->getTypesForExtension( substr( $extMime, 1 ) );
            if ( !$m ) {
                return MEDIATYPE_UNKNOWN;
            }
 
            $m = explode( ' ', $m );
        } else {
            // Normalize MIME type
            if ( isset( $this->mimeTypeAliases[$extMime] ) ) {
                $extMime = $this->mimeTypeAliases[$extMime];
            }
 
            $m = [ $extMime ];
        }
 
        foreach ( $m as $mime ) {
            foreach ( $this->mediaTypes as $type => $codes ) {
                if ( in_array( $mime, $codes, true ) ) {
                    return $type;
                }
            }
        }
 
        return MEDIATYPE_UNKNOWN;
    }
 
    public function getMediaTypes() {
        return array_keys( $this->mediaTypes );
    }
 
    public function getIEMimeTypes( $fileName, $chunk, $proposed ) {
        $ca = $this->getIEContentAnalyzer();
        return $ca->getRealMimesFromData( $fileName, $chunk, $proposed );
    }
 
    protected function getIEContentAnalyzer() {
        if ( $this->IEAnalyzer === null ) {
            $this->IEAnalyzer = new IEContentAnalyzer;
        }
        return $this->IEAnalyzer;
    }
}