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[mediawiki.git] / includes / upload / UploadBase.php

<?php
/**
 * @file
 * @ingroup upload
 *
 * UploadBase and subclasses are the backend of MediaWiki's file uploads.
 * The frontends are formed by ApiUpload and SpecialUpload.
 *
 * See also includes/docs/upload.txt
 *
 * @author Brion Vibber
 * @author Bryan Tong Minh
 * @author Michael Dale
 */

abstract class UploadBase {
        protected $mTempPath;
        protected $mDesiredDestName, $mDestName, $mRemoveTempFile, $mSourceType;
        protected $mTitle = false, $mTitleError = 0;
        protected $mFilteredName, $mFinalExtension;
        protected $mLocalFile;

        const SUCCESS = 0;
        const OK = 0;
        const EMPTY_FILE = 3;
        const MIN_LENGTH_PARTNAME = 4;
        const ILLEGAL_FILENAME = 5;
        const OVERWRITE_EXISTING_FILE = 7; # Not used anymore; handled by verifyPermissions()
        const FILETYPE_MISSING = 8;
        const FILETYPE_BADTYPE = 9;
        const VERIFICATION_ERROR = 10;

        # HOOK_ABORTED is the new name of UPLOAD_VERIFICATION_ERROR
        const UPLOAD_VERIFICATION_ERROR = 11;
        const HOOK_ABORTED = 11;
        const FILE_TOO_LARGE = 12;

        const SESSION_VERSION = 2;
        const SESSION_KEYNAME = 'wsUploadData';

        static public function getSessionKeyname() {
                return self::SESSION_KEYNAME;
        }

        public function getVerificationErrorCode( $error ) {
                $code_to_status = array(self::EMPTY_FILE => 'empty-file',
                                                                self::FILE_TOO_LARGE => 'file-too-large',
                                                                self::FILETYPE_MISSING => 'filetype-missing',
                                                                self::FILETYPE_BADTYPE => 'filetype-banned',
                                                                self::MIN_LENGTH_PARTNAME => 'filename-tooshort',
                                                                self::ILLEGAL_FILENAME => 'illegal-filename',
                                                                self::OVERWRITE_EXISTING_FILE => 'overwrite',
                                                                self::VERIFICATION_ERROR => 'verification-error',
                                                                self::HOOK_ABORTED =>  'hookaborted',
                );
                if( isset( $code_to_status[$error] ) ) {
                        return $code_to_status[$error];
                }

                return 'unknown-error';
        }

        /**
         * Returns true if uploads are enabled.
         * Can be override by subclasses.
         */
        public static function isEnabled() {
                global $wgEnableUploads;
                if ( !$wgEnableUploads ) {
                        return false;
                }

                # Check php's file_uploads setting
                if( !wfIniGetBool( 'file_uploads' ) ) {
                        return false;
                }
                return true;
        }

        /**
         * Returns true if the user can use this upload module or else a string
         * identifying the missing permission.
         * Can be overriden by subclasses.
         */
        public static function isAllowed( $user ) {
                foreach ( array( 'upload', 'edit' ) as $permission ) {
                        if ( !$user->isAllowed( $permission ) ) {
                                return $permission;
                        }
                }
                return true;
        }

        // Upload handlers. Should probably just be a global.
        static $uploadHandlers = array( 'Stash', 'File', 'Url' );

        /**
         * Create a form of UploadBase depending on wpSourceType and initializes it
         */
        public static function createFromRequest( &$request, $type = null ) {
                $type = $type ? $type : $request->getVal( 'wpSourceType', 'File' );

                if( !$type ) {
                        return null;
                }

                // Get the upload class
                $type = ucfirst( $type );

                // Give hooks the chance to handle this request
                $className = null;
                wfRunHooks( 'UploadCreateFromRequest', array( $type, &$className ) );
                if ( is_null( $className ) ) {
                        $className = 'UploadFrom' . $type;
                        wfDebug( __METHOD__ . ": class name: $className\n" );
                        if( !in_array( $type, self::$uploadHandlers ) ) {
                                return null;
                        }
                }

                // Check whether this upload class is enabled
                if( !call_user_func( array( $className, 'isEnabled' ) ) ) {
                        return null;
                }

                // Check whether the request is valid
                if( !call_user_func( array( $className, 'isValidRequest' ), $request ) ) {
                        return null;
                }

                $handler = new $className;

                $handler->initializeFromRequest( $request );
                return $handler;
        }

        /**
         * Check whether a request if valid for this handler
         */
        public static function isValidRequest( $request ) {
                return false;
        }

        public function __construct() {}
        
        /**
         * Returns the upload type. Should be overridden by child classes
         * 
         * @since 1.18
         * @return string 
         */
        public function getSourceType() { return null; }

        /**
         * Initialize the path information
         * @param $name string the desired destination name
         * @param $tempPath string the temporary path
         * @param $fileSize int the file size
         * @param $removeTempFile bool (false) remove the temporary file?
         * @return null
         */
        public function initializePathInfo( $name, $tempPath, $fileSize, $removeTempFile = false ) {
                $this->mDesiredDestName = $name;
                $this->mTempPath = $tempPath;
                $this->mFileSize = $fileSize;
                $this->mRemoveTempFile = $removeTempFile;
        }

        /**
         * Initialize from a WebRequest. Override this in a subclass.
         */
        public abstract function initializeFromRequest( &$request );

        /**
         * Fetch the file. Usually a no-op
         */
        public function fetchFile() {
                return Status::newGood();
        }

        /**
         * Return true if the file is empty
         * @return bool
         */
        public function isEmptyFile() {
                return empty( $this->mFileSize );
        }

        /**
         * Return the file size
         * @return integer
         */
        public function getFileSize() {
                return $this->mFileSize;
        }

        /**
         * Append a file to the Repo file
         *
         * @param $srcPath String: path to source file
         * @param $toAppendPath String: path to the Repo file that will be appended to.
         * @return Status Status
         */
        protected function appendToUploadFile( $srcPath, $toAppendPath ) {
                $repo = RepoGroup::singleton()->getLocalRepo();
                $status = $repo->append( $srcPath, $toAppendPath );
                return $status;
        }

        /**
         * @param $srcPath String: the source path
         * @return the real path if it was a virtual URL
         */
        function getRealPath( $srcPath ) {
                $repo = RepoGroup::singleton()->getLocalRepo();
                if ( $repo->isVirtualUrl( $srcPath ) ) {
                        return $repo->resolveVirtualUrl( $srcPath );
                }
                return $srcPath;
        }

        /**
         * Verify whether the upload is sane.
         * @return mixed self::OK or else an array with error information
         */
        public function verifyUpload() {
                /**
                 * If there was no filename or a zero size given, give up quick.
                 */
                if( $this->isEmptyFile() ) {
                        return array( 'status' => self::EMPTY_FILE );
                }

                /**
                 * Honor $wgMaxUploadSize
                 */
                $maxSize = self::getMaxUploadSize( $this->getSourceType() );
                if( $this->mFileSize > $maxSize ) {
                        return array( 
                                'status' => self::FILE_TOO_LARGE,
                                'max' => $maxSize,
                        );
                }

                /**
                 * Look at the contents of the file; if we can recognize the
                 * type but it's corrupt or data of the wrong type, we should
                 * probably not accept it.
                 */
                $verification = $this->verifyFile();
                if( $verification !== true ) {
                        return array(
                                'status' => self::VERIFICATION_ERROR,
                                'details' => $verification
                        );
                }

                /**
                 * Make sure this file can be created
                 */
                $result = $this->validateName();
                if( $result !== true ) {
                        return $result;
                }

                $error = '';
                if( !wfRunHooks( 'UploadVerification',
                                array( $this->mDestName, $this->mTempPath, &$error ) ) ) {
                        return array( 'status' => self::HOOK_ABORTED, 'error' => $error );
                }

                return array( 'status' => self::OK );
        }

        /**
         * Verify that the name is valid and, if necessary, that we can overwrite
         *
         * @return mixed true if valid, otherwise and array with 'status'
         * and other keys
         **/
        protected function validateName() {
                $nt = $this->getTitle();
                if( is_null( $nt ) ) {
                        $result = array( 'status' => $this->mTitleError );
                        if( $this->mTitleError == self::ILLEGAL_FILENAME ) {
                                $result['filtered'] = $this->mFilteredName;
                        }
                        if ( $this->mTitleError == self::FILETYPE_BADTYPE ) {
                                $result['finalExt'] = $this->mFinalExtension;
                                if ( count( $this->mBlackListedExtensions ) ) {
                                        $result['blacklistedExt'] = $this->mBlackListedExtensions;
                                }
                        }
                        return $result;
                }
                $this->mDestName = $this->getLocalFile()->getName();

                return true;
        }

        /**
         * Verify the mime type
         *
         * @param $mime string representing the mime
         * @return mixed true if the file is verified, an array otherwise
         */
        protected function verifyMimeType( $mime ) {
                global $wgVerifyMimeType;
                if ( $wgVerifyMimeType ) {
                        wfDebug ( "\n\nmime: <$mime> extension: <{$this->mFinalExtension}>\n\n");
                        global $wgMimeTypeBlacklist;
                        if ( $this->checkFileExtension( $mime, $wgMimeTypeBlacklist ) ) {
                                return array( 'filetype-badmime', $mime );
                        }

                        # XXX: Missing extension will be caught by validateName() via getTitle()
                        if ( $this->mFinalExtension != '' && !$this->verifyExtension( $mime, $this->mFinalExtension ) ) {
                                return array( 'filetype-mime-mismatch', $this->mFinalExtension, $mime );
                        }

                        # Check IE type
                        $fp = fopen( $this->mTempPath, 'rb' );
                        $chunk = fread( $fp, 256 );
                        fclose( $fp );

                        $magic = MimeMagic::singleton();
                        $extMime = $magic->guessTypesForExtension( $this->mFinalExtension );
                        $ieTypes = $magic->getIEMimeTypes( $this->mTempPath, $chunk, $extMime );
                        foreach ( $ieTypes as $ieType ) {
                                if ( $this->checkFileExtension( $ieType, $wgMimeTypeBlacklist ) ) {
                                        return array( 'filetype-bad-ie-mime', $ieType );
                                }
                        }
                }

                return true;
        }

        /**
         * Verifies that it's ok to include the uploaded file
         *
         * @return mixed true of the file is verified, array otherwise.
         */
        protected function verifyFile() {
                # get the title, even though we are doing nothing with it, because
                # we need to populate mFinalExtension 
                $this->getTitle();
                
                $this->mFileProps = File::getPropsFromPath( $this->mTempPath, $this->mFinalExtension );
                $this->checkMacBinary();

                # check mime type, if desired
                $mime = $this->mFileProps[ 'file-mime' ];
                $status = $this->verifyMimeType( $mime );
                if ( $status !== true ) {
                        return $status;
                }

                # check for htmlish code and javascript
                if( self::detectScript( $this->mTempPath, $mime, $this->mFinalExtension ) ) {
                        return array( 'uploadscripted' );
                }
                if( $this->mFinalExtension == 'svg' || $mime == 'image/svg+xml' ) {
                        if( $this->detectScriptInSvg( $this->mTempPath ) ) {
                                return array( 'uploadscripted' );
                        }
                }

                /**
                * Scan the uploaded file for viruses
                */
                $virus = $this->detectVirus( $this->mTempPath );
                if ( $virus ) {
                        return array( 'uploadvirus', $virus );
                }

                $handler = MediaHandler::getHandler( $mime );
                if ( $handler ) {
                        $handlerStatus = $handler->verifyUpload( $this->mTempPath );
                        if ( !$handlerStatus->isOK() ) {
                                $errors = $handlerStatus->getErrorsArray();
                                return reset( $errors );
                        }
                }

                wfRunHooks( 'UploadVerifyFile', array( $this, $mime, &$status ) );
                if ( $status !== true ) {
                        return $status;
                }

                wfDebug( __METHOD__ . ": all clear; passing.\n" );
                return true;
        }

        /**
         * Check whether the user can edit, upload and create the image. This
         * checks only against the current title; if it returns errors, it may
         * very well be that another title will not give errors. Therefore
         * isAllowed() should be called as well for generic is-user-blocked or
         * can-user-upload checking.
         *
         * @param $user the User object to verify the permissions against
         * @return mixed An array as returned by getUserPermissionsErrors or true
         *               in case the user has proper permissions.
         */
        public function verifyPermissions( $user ) {
                /**
                 * If the image is protected, non-sysop users won't be able
                 * to modify it by uploading a new revision.
                 */
                $nt = $this->getTitle();
                if( is_null( $nt ) ) {
                        return true;
                }
                $permErrors = $nt->getUserPermissionsErrors( 'edit', $user );
                $permErrorsUpload = $nt->getUserPermissionsErrors( 'upload', $user );
                if ( $nt->exists() ) {
                        $permErrorsCreate = $nt->getUserPermissionsErrors( 'createpage', $user );
                } else {
                        $permErrorsCreate = array();
                }
                if( $permErrors || $permErrorsUpload || $permErrorsCreate ) {
                        $permErrors = array_merge( $permErrors, wfArrayDiff2( $permErrorsUpload, $permErrors ) );
                        $permErrors = array_merge( $permErrors, wfArrayDiff2( $permErrorsCreate, $permErrors ) );
                        return $permErrors;
                }
                
                $overwriteError = $this->checkOverwrite( $user );
                if ( $overwriteError !== true ) {
                        return array( array( $overwriteError ) );
                }
                
                return true;
        }

        /**
         * Check for non fatal problems with the file
         *
         * @return Array of warnings
         */
        public function checkWarnings() {
                $warnings = array();

                $localFile = $this->getLocalFile();
                $filename = $localFile->getName();

                /**
                 * Check whether the resulting filename is different from the desired one,
                 * but ignore things like ucfirst() and spaces/underscore things
                 */
                $comparableName = str_replace( ' ', '_', $this->mDesiredDestName );
                $comparableName = Title::capitalize( $comparableName, NS_FILE );

                if( $this->mDesiredDestName != $filename && $comparableName != $filename ) {
                        $warnings['badfilename'] = $filename;
                }

                // Check whether the file extension is on the unwanted list
                global $wgCheckFileExtensions, $wgFileExtensions;
                if ( $wgCheckFileExtensions ) {
                        if ( !$this->checkFileExtension( $this->mFinalExtension, $wgFileExtensions ) ) {
                                $warnings['filetype-unwanted-type'] = $this->mFinalExtension;
                        }
                }

                global $wgUploadSizeWarning;
                if ( $wgUploadSizeWarning && ( $this->mFileSize > $wgUploadSizeWarning ) ) {
                        $warnings['large-file'] = $wgUploadSizeWarning;
                }

                if ( $this->mFileSize == 0 ) {
                        $warnings['emptyfile'] = true;
                }

                $exists = self::getExistsWarning( $localFile );
                if( $exists !== false ) {
                        $warnings['exists'] = $exists;
                }

                // Check dupes against existing files
                $hash = File::sha1Base36( $this->mTempPath );
                $dupes = RepoGroup::singleton()->findBySha1( $hash );
                $title = $this->getTitle();
                // Remove all matches against self
                foreach ( $dupes as $key => $dupe ) {
                        if( $title->equals( $dupe->getTitle() ) ) {
                                unset( $dupes[$key] );
                        }
                }
                if( $dupes ) {
                        $warnings['duplicate'] = $dupes;
                }

                // Check dupes against archives
                $archivedImage = new ArchivedFile( null, 0, "{$hash}.{$this->mFinalExtension}" );
                if ( $archivedImage->getID() > 0 ) {
                        $warnings['duplicate-archive'] = $archivedImage->getName();
                }

                return $warnings;
        }

        /**
         * Really perform the upload. Stores the file in the local repo, watches
         * if necessary and runs the UploadComplete hook.
         *
         * @return Status indicating the whether the upload succeeded.
         */
        public function performUpload( $comment, $pageText, $watch, $user ) {
                $status = $this->getLocalFile()->upload( 
                        $this->mTempPath, 
                        $comment, 
                        $pageText,
                        File::DELETE_SOURCE,
                        $this->mFileProps, 
                        false, 
                        $user 
                );

                if( $status->isGood() ) {
                        if ( $watch ) {
                                $user->addWatch( $this->getLocalFile()->getTitle() );
                        }

                        wfRunHooks( 'UploadComplete', array( &$this ) );
                }

                return $status;
        }

        /**
         * Returns the title of the file to be uploaded. Sets mTitleError in case
         * the name was illegal.
         *
         * @return Title The title of the file or null in case the name was illegal
         */
        public function getTitle() {
                if ( $this->mTitle !== false ) {
                        return $this->mTitle;
                }

                /**
                 * Chop off any directories in the given filename. Then
                 * filter out illegal characters, and try to make a legible name
                 * out of it. We'll strip some silently that Title would die on.
                 */
                $this->mFilteredName = wfStripIllegalFilenameChars( $this->mDesiredDestName );
                /* Normalize to title form before we do any further processing */
                $nt = Title::makeTitleSafe( NS_FILE, $this->mFilteredName );
                if( is_null( $nt ) ) {
                        $this->mTitleError = self::ILLEGAL_FILENAME;
                        return $this->mTitle = null;
                }
                $this->mFilteredName = $nt->getDBkey();

                /**
                 * We'll want to blacklist against *any* 'extension', and use
                 * only the final one for the whitelist.
                 */
                list( $partname, $ext ) = $this->splitExtensions( $this->mFilteredName );

                if( count( $ext ) ) {
                        $this->mFinalExtension = trim( $ext[count( $ext ) - 1] );
                } else {
                        $this->mFinalExtension = '';
                        
                        # No extension, try guessing one
                        $magic = MimeMagic::singleton();
                        $mime = $magic->guessMimeType( $this->mTempPath );
                        if ( $mime !== 'unknown/unknown' ) {
                                # Get a space separated list of extensions
                                $extList = $magic->getExtensionsForType( $mime );
                                if ( $extList ) {
                                        # Set the extension to the canonical extension
                                        $this->mFinalExtension = strtok( $extList, ' ' );
                                        
                                        # Fix up the other variables
                                        $this->mFilteredName .= ".{$this->mFinalExtension}";
                                        $nt = Title::makeTitleSafe( NS_FILE, $this->mFilteredName );
                                        $ext = array( $this->mFinalExtension );
                                }
                        }
                        
                }

                /* Don't allow users to override the blacklist (check file extension) */
                global $wgCheckFileExtensions, $wgStrictFileExtensions;
                global $wgFileExtensions, $wgFileBlacklist;
                
                $blackListedExtensions = $this->checkFileExtensionList( $ext, $wgFileBlacklist );
                
                if ( $this->mFinalExtension == '' ) {
                        $this->mTitleError = self::FILETYPE_MISSING;
                        return $this->mTitle = null;
                } elseif ( $blackListedExtensions ||
                                ( $wgCheckFileExtensions && $wgStrictFileExtensions &&
                                        !$this->checkFileExtension( $this->mFinalExtension, $wgFileExtensions ) ) ) {
                        $this->mBlackListedExtensions = $blackListedExtensions;
                        $this->mTitleError = self::FILETYPE_BADTYPE;
                        return $this->mTitle = null;
                }

                # If there was more than one "extension", reassemble the base
                # filename to prevent bogus complaints about length
                if( count( $ext ) > 1 ) {
                        for( $i = 0; $i < count( $ext ) - 1; $i++ ) {
                                $partname .= '.' . $ext[$i];
                        }
                }

                if( strlen( $partname ) < 1 ) {
                        $this->mTitleError =  self::MIN_LENGTH_PARTNAME;
                        return $this->mTitle = null;
                }

                return $this->mTitle = $nt;
        }

        /**
         * Return the local file and initializes if necessary.
         */
        public function getLocalFile() {
                if( is_null( $this->mLocalFile ) ) {
                        $nt = $this->getTitle();
                        $this->mLocalFile = is_null( $nt ) ? null : wfLocalFile( $nt );
                }
                return $this->mLocalFile;
        }

        /**
         * NOTE: Probably should be deprecated in favor of UploadStash, but this is sometimes
         * called outside that context.
         *
         * Stash a file in a temporary directory for later processing
         * after the user has confirmed it.
         *
         * If the user doesn't explicitly cancel or accept, these files
         * can accumulate in the temp directory.
         *
         * @param $saveName String: the destination filename
         * @param $tempSrc String: the source temporary file to save
         * @return String: full path the stashed file, or false on failure
         */
        protected function saveTempUploadedFile( $saveName, $tempSrc ) {
                $repo = RepoGroup::singleton()->getLocalRepo();
                $status = $repo->storeTemp( $saveName, $tempSrc );
                return $status;
        }

        /**
         * If the user does not supply all necessary information in the first upload form submission (either by accident or
         * by design) then we may want to stash the file temporarily, get more information, and publish the file later.
         *
         * This method will stash a file in a temporary directory for later processing, and save the necessary descriptive info
         * into the user's session.
         * This method returns the file object, which also has a 'sessionKey' property which can be passed through a form or 
         * API request to find this stashed file again.
         *
         * @param $key String: (optional) the session key used to find the file info again. If not supplied, a key will be autogenerated.
         * @return File stashed file
         */
        public function stashSessionFile( $key = null ) { 
                $stash = RepoGroup::singleton()->getLocalRepo()->getUploadStash();
                $data = array( 
                        'mFileProps' => $this->mFileProps,
                        'mSourceType' => $this->getSourceType(),
                );
                $file = $stash->stashFile( $this->mTempPath, $data, $key );
                $this->mLocalFile = $file;
                return $file;
        }

        /**
         * Stash a file in a temporary directory, returning a key which can be used to find the file again. See stashSessionFile().
         *
         * @param $key String: (optional) the session key used to find the file info again. If not supplied, a key will be autogenerated.
         * @return String: session key
         */
        public function stashSession( $key = null ) {
                return $this->stashSessionFile( $key )->getSessionKey();
        }

        /**
         * If we've modified the upload file we need to manually remove it
         * on exit to clean up.
         */
        public function cleanupTempFile() {
                if ( $this->mRemoveTempFile && $this->mTempPath && file_exists( $this->mTempPath ) ) {
                        wfDebug( __METHOD__ . ": Removing temporary file {$this->mTempPath}\n" );
                        unlink( $this->mTempPath );
                }
        }

        public function getTempPath() {
                return $this->mTempPath;
        }

        /**
         * Split a file into a base name and all dot-delimited 'extensions'
         * on the end. Some web server configurations will fall back to
         * earlier pseudo-'extensions' to determine type and execute
         * scripts, so the blacklist needs to check them all.
         *
         * @return array
         */
        public static function splitExtensions( $filename ) {
                $bits = explode( '.', $filename );
                $basename = array_shift( $bits );
                return array( $basename, $bits );
        }

        /**
         * Perform case-insensitive match against a list of file extensions.
         * Returns true if the extension is in the list.
         *
         * @param $ext String
         * @param $list Array
         * @return Boolean
         */
        public static function checkFileExtension( $ext, $list ) {
                return in_array( strtolower( $ext ), $list );
        }

        /**
         * Perform case-insensitive match against a list of file extensions.
         * Returns an array of matching extensions.
         *
         * @param $ext Array
         * @param $list Array
         * @return Boolean
         */
        public static function checkFileExtensionList( $ext, $list ) {
                return array_intersect( array_map( 'strtolower', $ext ), $list );
        }

        /**
         * Checks if the mime type of the uploaded file matches the file extension.
         *
         * @param $mime String: the mime type of the uploaded file
         * @param $extension String: the filename extension that the file is to be served with
         * @return Boolean
         */
        public static function verifyExtension( $mime, $extension ) {
                $magic = MimeMagic::singleton();

                if ( !$mime || $mime == 'unknown' || $mime == 'unknown/unknown' )
                        if ( !$magic->isRecognizableExtension( $extension ) ) {
                                wfDebug( __METHOD__ . ": passing file with unknown detected mime type; " .
                                        "unrecognized extension '$extension', can't verify\n" );
                                return true;
                        } else {
                                wfDebug( __METHOD__ . ": rejecting file with unknown detected mime type; ".
                                        "recognized extension '$extension', so probably invalid file\n" );
                                return false;
                        }

                $match = $magic->isMatchingExtension( $extension, $mime );

                if ( $match === null ) {
                        wfDebug( __METHOD__ . ": no file extension known for mime type $mime, passing file\n" );
                        return true;
                } elseif( $match === true ) {
                        wfDebug( __METHOD__ . ": mime type $mime matches extension $extension, passing file\n" );

                        #TODO: if it's a bitmap, make sure PHP or ImageMagic resp. can handle it!
                        return true;

                } else {
                        wfDebug( __METHOD__ . ": mime type $mime mismatches file extension $extension, rejecting file\n" );
                        return false;
                }
        }

        /**
         * Heuristic for detecting files that *could* contain JavaScript instructions or
         * things that may look like HTML to a browser and are thus
         * potentially harmful. The present implementation will produce false
         * positives in some situations.
         *
         * @param $file String: pathname to the temporary upload file
         * @param $mime String: the mime type of the file
         * @param $extension String: the extension of the file
         * @return Boolean: true if the file contains something looking like embedded scripts
         */
        public static function detectScript( $file, $mime, $extension ) {
                global $wgAllowTitlesInSVG;

                # ugly hack: for text files, always look at the entire file.
                # For binary field, just check the first K.

                if( strpos( $mime,'text/' ) === 0 ) {
                        $chunk = file_get_contents( $file );
                } else {
                        $fp = fopen( $file, 'rb' );
                        $chunk = fread( $fp, 1024 );
                        fclose( $fp );
                }

                $chunk = strtolower( $chunk );

                if( !$chunk ) {
                        return false;
                }

                # decode from UTF-16 if needed (could be used for obfuscation).
                if( substr( $chunk, 0, 2 ) == "\xfe\xff" ) {
                        $enc = 'UTF-16BE';
                } elseif( substr( $chunk, 0, 2 ) == "\xff\xfe" ) {
                        $enc = 'UTF-16LE';
                } else {
                        $enc = null;
                }

                if( $enc ) {
                        $chunk = iconv( $enc, "ASCII//IGNORE", $chunk );
                }

                $chunk = trim( $chunk );

                # FIXME: convert from UTF-16 if necessarry!
                wfDebug( __METHOD__ . ": checking for embedded scripts and HTML stuff\n" );

                # check for HTML doctype
                if ( preg_match( "/<!DOCTYPE *X?HTML/i", $chunk ) ) {
                        return true;
                }

                /**
                 * Internet Explorer for Windows performs some really stupid file type
                 * autodetection which can cause it to interpret valid image files as HTML
                 * and potentially execute JavaScript, creating a cross-site scripting
                 * attack vectors.
                 *
                 * Apple's Safari browser also performs some unsafe file type autodetection
                 * which can cause legitimate files to be interpreted as HTML if the
                 * web server is not correctly configured to send the right content-type
                 * (or if you're really uploading plain text and octet streams!)
                 *
                 * Returns true if IE is likely to mistake the given file for HTML.
                 * Also returns true if Safari would mistake the given file for HTML
                 * when served with a generic content-type.
                 */
                $tags = array(
                        '<a href',
                        '<body',
                        '<head',
                        '<html',   #also in safari
                        '<img',
                        '<pre',
                        '<script', #also in safari
                        '<table'
                );

                if( !$wgAllowTitlesInSVG && $extension !== 'svg' && $mime !== 'image/svg' ) {
                        $tags[] = '<title';
                }

                foreach( $tags as $tag ) {
                        if( false !== strpos( $chunk, $tag ) ) {
                                return true;
                        }
                }

                /*
                 * look for JavaScript
                 */

                # resolve entity-refs to look at attributes. may be harsh on big files... cache result?
                $chunk = Sanitizer::decodeCharReferences( $chunk );

                # look for script-types
                if( preg_match( '!type\s*=\s*[\'"]?\s*(?:\w*/)?(?:ecma|java)!sim', $chunk ) ) {
                        return true;
                }

                # look for html-style script-urls
                if( preg_match( '!(?:href|src|data)\s*=\s*[\'"]?\s*(?:ecma|java)script:!sim', $chunk ) ) {
                        return true;
                }

                # look for css-style script-urls
                if( preg_match( '!url\s*\(\s*[\'"]?\s*(?:ecma|java)script:!sim', $chunk ) ) {
                        return true;
                }

                wfDebug( __METHOD__ . ": no scripts found\n" );
                return false;
        }

        protected function detectScriptInSvg( $filename ) {
                $check = new XmlTypeCheck( $filename, array( $this, 'checkSvgScriptCallback' ) );
                return $check->filterMatch;
        }

        /**
         * @todo Replace this with a whitelist filter!
         */
        public function checkSvgScriptCallback( $element, $attribs ) {
                $stripped = $this->stripXmlNamespace( $element );

                if( $stripped == 'script' ) {
                        wfDebug( __METHOD__ . ": Found script element '$element' in uploaded file.\n" );
                        return true;
                }

                foreach( $attribs as $attrib => $value ) {
                        $stripped = $this->stripXmlNamespace( $attrib );
                        if( substr( $stripped, 0, 2 ) == 'on' ) {
                                wfDebug( __METHOD__ . ": Found script attribute '$attrib'='value' in uploaded file.\n" );
                                return true;
                        }
                        if( $stripped == 'href' && strpos( strtolower( $value ), 'javascript:' ) !== false ) {
                                wfDebug( __METHOD__ . ": Found script href attribute '$attrib'='$value' in uploaded file.\n" );
                                return true;
                        }
                }
        }

        private function stripXmlNamespace( $name ) {
                // 'http://www.w3.org/2000/svg:script' -> 'script'
                $parts = explode( ':', strtolower( $name ) );
                return array_pop( $parts );
        }

        /**
         * Generic wrapper function for a virus scanner program.
         * This relies on the $wgAntivirus and $wgAntivirusSetup variables.
         * $wgAntivirusRequired may be used to deny upload if the scan fails.
         *
         * @param $file String: pathname to the temporary upload file
         * @return mixed false if not virus is found, NULL if the scan fails or is disabled,
         *         or a string containing feedback from the virus scanner if a virus was found.
         *         If textual feedback is missing but a virus was found, this function returns true.
         */
        public static function detectVirus( $file ) {
                global $wgAntivirus, $wgAntivirusSetup, $wgAntivirusRequired, $wgOut;

                if ( !$wgAntivirus ) {
                        wfDebug( __METHOD__ . ": virus scanner disabled\n" );
                        return null;
                }

                if ( !$wgAntivirusSetup[$wgAntivirus] ) {
                        wfDebug( __METHOD__ . ": unknown virus scanner: $wgAntivirus\n" );
                        $wgOut->wrapWikiMsg( "<div class=\"error\">\n$1\n</div>",
                                array( 'virus-badscanner', $wgAntivirus ) );
                        return wfMsg( 'virus-unknownscanner' ) . " $wgAntivirus";
                }

                # look up scanner configuration
                $command = $wgAntivirusSetup[$wgAntivirus]['command'];
                $exitCodeMap = $wgAntivirusSetup[$wgAntivirus]['codemap'];
                $msgPattern = isset( $wgAntivirusSetup[$wgAntivirus]['messagepattern'] ) ?
                        $wgAntivirusSetup[$wgAntivirus]['messagepattern'] : null;

                if ( strpos( $command, "%f" ) === false ) {
                        # simple pattern: append file to scan
                        $command .= " " . wfEscapeShellArg( $file );
                } else {
                        # complex pattern: replace "%f" with file to scan
                        $command = str_replace( "%f", wfEscapeShellArg( $file ), $command );
                }

                wfDebug( __METHOD__ . ": running virus scan: $command \n" );

                # execute virus scanner
                $exitCode = false;

                # NOTE: there's a 50 line workaround to make stderr redirection work on windows, too.
                #      that does not seem to be worth the pain.
                #      Ask me (Duesentrieb) about it if it's ever needed.
                $output = wfShellExec( "$command 2>&1", $exitCode );

                # map exit code to AV_xxx constants.
                $mappedCode = $exitCode;
                if ( $exitCodeMap ) {
                        if ( isset( $exitCodeMap[$exitCode] ) ) {
                                $mappedCode = $exitCodeMap[$exitCode];
                        } elseif ( isset( $exitCodeMap["*"] ) ) {
                                $mappedCode = $exitCodeMap["*"];
                        }
                }

                if ( $mappedCode === AV_SCAN_FAILED ) {
                        # scan failed (code was mapped to false by $exitCodeMap)
                        wfDebug( __METHOD__ . ": failed to scan $file (code $exitCode).\n" );

                        if ( $wgAntivirusRequired ) {
                                return wfMsg( 'virus-scanfailed', array( $exitCode ) );
                        } else {
                                return null;
                        }
                } elseif ( $mappedCode === AV_SCAN_ABORTED ) {
                        # scan failed because filetype is unknown (probably imune)
                        wfDebug( __METHOD__ . ": unsupported file type $file (code $exitCode).\n" );
                        return null;
                } elseif ( $mappedCode === AV_NO_VIRUS ) {
                        # no virus found
                        wfDebug( __METHOD__ . ": file passed virus scan.\n" );
                        return false;
                } else {
                        $output = trim( $output );

                        if ( !$output ) {
                                $output = true; #if there's no output, return true
                        } elseif ( $msgPattern ) {
                                $groups = array();
                                if ( preg_match( $msgPattern, $output, $groups ) ) {
                                        if ( $groups[1] ) {
                                                $output = $groups[1];
                                        }
                                }
                        }

                        wfDebug( __METHOD__ . ": FOUND VIRUS! scanner feedback: $output \n" );
                        return $output;
                }
        }

        /**
         * Check if the temporary file is MacBinary-encoded, as some uploads
         * from Internet Explorer on Mac OS Classic and Mac OS X will be.
         * If so, the data fork will be extracted to a second temporary file,
         * which will then be checked for validity and either kept or discarded.
         */
        private function checkMacBinary() {
                $macbin = new MacBinary( $this->mTempPath );
                if( $macbin->isValid() ) {
                        $dataFile = tempnam( wfTempDir(), 'WikiMacBinary' );
                        $dataHandle = fopen( $dataFile, 'wb' );

                        wfDebug( __METHOD__ . ": Extracting MacBinary data fork to $dataFile\n" );
                        $macbin->extractData( $dataHandle );

                        $this->mTempPath = $dataFile;
                        $this->mFileSize = $macbin->dataForkLength();

                        // We'll have to manually remove the new file if it's not kept.
                        $this->mRemoveTempFile = true;
                }
                $macbin->close();
        }

        /**
         * Check if there's an overwrite conflict and, if so, if restrictions
         * forbid this user from performing the upload.
         *
         * @return mixed true on success, error string on failure
         */
        private function checkOverwrite( $user ) {
                // First check whether the local file can be overwritten
                $file = $this->getLocalFile();
                if( $file->exists() ) {
                        if( !self::userCanReUpload( $user, $file ) ) {
                                return 'fileexists-forbidden';
                        } else {
                                return true;
                        }
                }

                /* Check shared conflicts: if the local file does not exist, but
                 * wfFindFile finds a file, it exists in a shared repository.
                 */
                $file = wfFindFile( $this->getTitle() );
                if ( $file && !$user->isAllowed( 'reupload-shared' ) ) {
                        return 'fileexists-shared-forbidden';
                }

                return true;
        }

        /**
         * Check if a user is the last uploader
         *
         * @param $user User object
         * @param $img String: image name
         * @return Boolean
         */
        public static function userCanReUpload( User $user, $img ) {
                if( $user->isAllowed( 'reupload' ) ) {
                        return true; // non-conditional
                }
                if( !$user->isAllowed( 'reupload-own' ) ) {
                        return false;
                }
                if( is_string( $img ) ) {
                        $img = wfLocalFile( $img );
                }
                if ( !( $img instanceof LocalFile ) ) {
                        return false;
                }

                return $user->getId() == $img->getUser( 'id' );
        }

        /**
         * Helper function that does various existence checks for a file.
         * The following checks are performed:
         * - The file exists
         * - Article with the same name as the file exists
         * - File exists with normalized extension
         * - The file looks like a thumbnail and the original exists
         *
         * @param $file File The File object to check
         * @return mixed False if the file does not exists, else an array
         */
        public static function getExistsWarning( $file ) {
                if( $file->exists() ) {
                        return array( 'warning' => 'exists', 'file' => $file );
                }

                if( $file->getTitle()->getArticleID() ) {
                        return array( 'warning' => 'page-exists', 'file' => $file );
                }

                if ( $file->wasDeleted() && !$file->exists() ) {
                        return array( 'warning' => 'was-deleted', 'file' => $file );
                }

                if( strpos( $file->getName(), '.' ) == false ) {
                        $partname = $file->getName();
                        $extension = '';
                } else {
                        $n = strrpos( $file->getName(), '.' );
                        $extension = substr( $file->getName(), $n + 1 );
                        $partname = substr( $file->getName(), 0, $n );
                }
                $normalizedExtension = File::normalizeExtension( $extension );

                if ( $normalizedExtension != $extension ) {
                        // We're not using the normalized form of the extension.
                        // Normal form is lowercase, using most common of alternate
                        // extensions (eg 'jpg' rather than 'JPEG').
                        //
                        // Check for another file using the normalized form...
                        $nt_lc = Title::makeTitle( NS_FILE, "{$partname}.{$normalizedExtension}" );
                        $file_lc = wfLocalFile( $nt_lc );

                        if( $file_lc->exists() ) {
                                return array(
                                        'warning' => 'exists-normalized',
                                        'file' => $file,
                                        'normalizedFile' => $file_lc
                                );
                        }
                }

                if ( self::isThumbName( $file->getName() ) ) {
                        # Check for filenames like 50px- or 180px-, these are mostly thumbnails
                        $nt_thb = Title::newFromText( substr( $partname , strpos( $partname , '-' ) +1 ) . '.' . $extension, NS_FILE );
                        $file_thb = wfLocalFile( $nt_thb );
                        if( $file_thb->exists() ) {
                                return array(
                                        'warning' => 'thumb',
                                        'file' => $file,
                                        'thumbFile' => $file_thb
                                );
                        } else {
                                // File does not exist, but we just don't like the name
                                return array(
                                        'warning' => 'thumb-name',
                                        'file' => $file,
                                        'thumbFile' => $file_thb
                                );
                        }
                }


                foreach( self::getFilenamePrefixBlacklist() as $prefix ) {
                        if ( substr( $partname, 0, strlen( $prefix ) ) == $prefix ) {
                                return array(
                                        'warning' => 'bad-prefix',
                                        'file' => $file,
                                        'prefix' => $prefix
                                );
                        }
                }

                return false;
        }

        /**
         * Helper function that checks whether the filename looks like a thumbnail
         */
        public static function isThumbName( $filename ) {
                $n = strrpos( $filename, '.' );
                $partname = $n ? substr( $filename, 0, $n ) : $filename;
                return (
                                        substr( $partname , 3, 3 ) == 'px-' ||
                                        substr( $partname , 2, 3 ) == 'px-'
                                ) &&
                                preg_match( "/[0-9]{2}/" , substr( $partname , 0, 2 ) );
        }

        /**
         * Get a list of blacklisted filename prefixes from [[MediaWiki:Filename-prefix-blacklist]]
         *
         * @return array list of prefixes
         */
        public static function getFilenamePrefixBlacklist() {
                $blacklist = array();
                $message = wfMessage( 'filename-prefix-blacklist' )->inContentLanguage();
                if( !$message->isDisabled() ) {
                        $lines = explode( "\n", $message->plain() );
                        foreach( $lines as $line ) {
                                // Remove comment lines
                                $comment = substr( trim( $line ), 0, 1 );
                                if ( $comment == '#' || $comment == '' ) {
                                        continue;
                                }
                                // Remove additional comments after a prefix
                                $comment = strpos( $line, '#' );
                                if ( $comment > 0 ) {
                                        $line = substr( $line, 0, $comment-1 );
                                }
                                $blacklist[] = trim( $line );
                        }
                }
                return $blacklist;
        }

        /**
         * Gets image info about the file just uploaded. 
         *
         * Also has the effect of setting metadata to be an 'indexed tag name' in returned API result if 
         * 'metadata' was requested. Oddly, we have to pass the "result" object down just so it can do that
         * with the appropriate format, presumably. 
         *
         * @param $result ApiResult:
         * @return Array: image info
         */
        public function getImageInfo( $result ) {
                $file = $this->getLocalFile();
                // TODO This cries out for refactoring. We really want to say $file->getAllInfo(); here. 
                // Perhaps "info" methods should be moved into files, and the API should just wrap them in queries.
                if ( $file instanceof UploadStashFile ) {
                        $imParam = ApiQueryStashImageInfo::getPropertyNames();
                        $info = ApiQueryStashImageInfo::getInfo( $file, array_flip( $imParam ), $result );
                } else {
                        $imParam = ApiQueryImageInfo::getPropertyNames();
                        $info = ApiQueryImageInfo::getInfo( $file, array_flip( $imParam ), $result );
                }
                return $info;
        }


        public function convertVerifyErrorToStatus( $error ) {
                $code = $error['status'];
                unset( $code['status'] );
                return Status::newFatal( $this->getVerificationErrorCode( $code ), $error );
        }
        
        public static function getMaxUploadSize( $forType = null ) {
                global $wgMaxUploadSize;
                
                if ( is_array( $wgMaxUploadSize ) ) {
                        if ( !is_null( $forType) && isset( $wgMaxUploadSize[$forType] ) ) {
                                return $wgMaxUploadSize[$forType];
                        } else {
                                return $wgMaxUploadSize['*'];
                        }
                } else {
                        return intval( $wgMaxUploadSize );
                }
                
        }
}