MimeTypeDetector.php

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<?php
namespace Elgg\Filesystem;

class MimeTypeDetector {

    const DEFAULT_TYPE = 'application/octet-stream';

    public $strategies = [
        [__CLASS__, 'tryFinfo'],
        [__CLASS__, 'tryMimeContentType'],
        [__CLASS__, 'tryFile'],
        [__CLASS__, 'tryGetimagesize'],
    ];

    public $use_extension = true;

    public $extensions = [
        'txt' => 'text/plain',
        'htm' => 'text/html',
        'html' => 'text/html',
        'php' => 'text/html',
        'css' => 'text/css',
        'js' => 'text/javascript',
        'mjs' => 'text/javascript',
        'json' => 'application/json',
        'xml' => 'application/xml',
        'swf' => 'application/x-shockwave-flash',
        'flv' => 'video/x-flv',

        // images
        'png' => 'image/png',
        'jpe' => 'image/jpeg',
        'jpeg' => 'image/jpeg',
        'jpg' => 'image/jpeg',
        'gif' => 'image/gif',
        'bmp' => 'image/bmp',
        'ico' => 'image/vnd.microsoft.icon',
        'tiff' => 'image/tiff',
        'tif' => 'image/tiff',
        'svg' => 'image/svg+xml',
        'svgz' => 'image/svg+xml',
        'webp' => 'image/webp',

        // archives
        'zip' => 'application/zip',
        'rar' => 'application/x-rar-compressed',
        'exe' => 'application/x-msdownload',
        'msi' => 'application/x-msdownload',
        'cab' => 'application/vnd.ms-cab-compressed',

        // audio/video
        'mp3' => 'audio/mpeg',
        'qt' => 'video/quicktime',
        'mov' => 'video/quicktime',

        // adobe
        'pdf' => 'application/pdf',
        'psd' => 'image/vnd.adobe.photoshop',
        'ai' => 'application/postscript',
        'eps' => 'application/postscript',
        'ps' => 'application/postscript',

        // open office
        'odt' => 'application/vnd.oasis.opendocument.text',
        'ods' => 'application/vnd.oasis.opendocument.spreadsheet',

        // office
        'doc' => 'application/msword',
        'rtf' => 'application/rtf',
        'xls' => 'application/vnd.ms-excel',
        'ppt' => 'application/vnd.ms-powerpoint',
        'docx' => 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
        'docm' => 'application/vnd.ms-word.document.macroEnabled.12',
        'dotx' => 'application/vnd.openxmlformats-officedocument.wordprocessingml.template',
        'dotm' => 'application/vnd.ms-word.template.macroEnabled.12',
        'xlsx' => 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
        'xlsm' => 'application/vnd.ms-excel.sheet.macroEnabled.12',
        'xltx' => 'application/vnd.openxmlformats-officedocument.spreadsheetml.template',
        'xltm' => 'application/vnd.ms-excel.template.macroEnabled.12',
        'xlsb' => 'application/vnd.ms-excel.sheet.binary.macroEnabled.12',
        'xlam' => 'application/vnd.ms-excel.addin.macroEnabled.12',
        'pptx' => 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
        'pptm' => 'application/vnd.ms-powerpoint.presentation.macroEnabled.12',
        'ppsx' => 'application/vnd.openxmlformats-officedocument.presentationml.slideshow',
        'ppsm' => 'application/vnd.ms-powerpoint.slideshow.macroEnabled.12',
        'potx' => 'application/vnd.openxmlformats-officedocument.presentationml.template',
        'potm' => 'application/vnd.ms-powerpoint.template.macroEnabled.12',
        'ppam' => 'application/vnd.ms-powerpoint.addin.macroEnabled.12',
        'sldx' => 'application/vnd.openxmlformats-officedocument.presentationml.slide',
        'sldm' => 'application/vnd.ms-powerpoint.slide.macroEnabled.12',
        'one' => 'application/msonenote',
        'onetoc2' => 'application/msonenote',
        'onetmp' => 'application/msonenote',
        'onepkg' => 'application/msonenote',
        'thmx' => 'application/vnd.ms-officetheme',
    ];

    public function getType($file, $default = self::DEFAULT_TYPE) {
        // Check only existing files
        if (!is_file($file) || !is_readable($file)) {
            return $default;
        }

        $ext = pathinfo($file, PATHINFO_EXTENSION);

        $type = $this->tryStrategies($file);

        if ($type) {
            return $this->fixDetectionErrors($type, $ext);
        }

        if ($this->use_extension && isset($this->extensions[$ext])) {
            return $this->extensions[$ext];
        }

        return $default;
    }

    public function tryStrategies($file) {
        foreach ($this->strategies as $strategy) {
            $type = call_user_func($strategy, $file);
            if (!empty($type)) {
                return $type;
            }
        }
        
        return '';
    }

    public function fixDetectionErrors($type, $extension) {
        if ($type === 'application/zip') {
            // hack for Microsoft zipped formats
            switch ($extension) {
                case 'docx':
                    return 'application/vnd.openxmlformats-officedocument.wordprocessingml.document';
                case 'xlsx':
                    return 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet';
                case 'pptx':
                    return 'application/vnd.openxmlformats-officedocument.presentationml.presentation';
            }
        }

        // check for bad ppt detection
        if ($type === 'application/vnd.ms-office' && $extension === 'ppt') {
            return 'application/vnd.ms-powerpoint';
        }

        // bad css/js detection
        if ($type === 'text/plain' && in_array($extension, ['css', 'js', 'mjs'])) {
            return $this->extensions[$extension];
        }
        
        // try extension detection as a fallback for octet-stream
        if ($type === 'application/octet-stream' && $this->use_extension && isset($this->extensions[$extension])) {
            return $this->extensions[$extension];
        }

        return $type;
    }

    public static function tryFinfo($file) {
        if (!function_exists('finfo_open')) {
            return '';
        }

        $finfo = finfo_open(FILEINFO_MIME);
        $type = finfo_file($finfo, $file);
        finfo_close($finfo);
        // Mimetype can come in text/plain; charset=us-ascii form
        if (strpos($type, ';')) {
            list($type,) = explode(';', $type);
        }
        
        return $type;
    }

    public static function tryMimeContentType($file) {
        return function_exists('mime_content_type') ? mime_content_type($file) : '';
    }

    public static function tryFile($file) {
        if (DIRECTORY_SEPARATOR !== '/' || !function_exists('exec')) {
            return '';
        }
        
        $type = @exec('file -b --mime-type ' . escapeshellarg($file));
        return $type ?: '';
    }

    public static function tryGetimagesize($file) {
        $data = @getimagesize($file);
        return empty($data['mime']) ? '' : $data['mime'];
    }
}