Implement extension registration from an extension.json file

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

<?php
/**
 * Base class for the backend of file upload.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup Upload
 */

/**
 * @defgroup Upload Upload related
 */

/**
 * @ingroup Upload
 *
 * UploadBase and subclasses are the backend of MediaWiki's file uploads.
 * The frontends are formed by ApiUpload and SpecialUpload.
 *
 * @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, $mFileSize, $mFileProps;
        protected $mBlackListedExtensions;
        protected $mJavaDetected, $mSVGNSError;

        protected static $safeXmlEncodings = array(
                'UTF-8',
                'ISO-8859-1',
                'ISO-8859-2',
                'UTF-16',
                'UTF-32'
        );

        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 verifyTitlePermissions()
        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 WINDOWS_NONASCII_FILENAME = 13;
        const FILENAME_TOO_LONG = 14;

        /**
         * @param int $error
         * @return string
         */
        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',
                        self::WINDOWS_NONASCII_FILENAME => 'windows-nonascii-filename',
                        self::FILENAME_TOO_LONG => 'filename-toolong',
                );
                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.
         * @return bool
         */
        public static function isEnabled() {
                global $wgEnableUploads;

                if ( !$wgEnableUploads ) {
                        return false;
                }

                # Check php's file_uploads setting
                return wfIsHHVM() || wfIniGetBool( 'file_uploads' );
        }

        /**
         * Returns true if the user can use this upload module or else a string
         * identifying the missing permission.
         * Can be overridden by subclasses.
         *
         * @param User $user
         * @return bool|string
         */
        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.
        private static $uploadHandlers = array( 'Stash', 'File', 'Url' );

        /**
         * Create a form of UploadBase depending on wpSourceType and initializes it
         *
         * @param WebRequest $request
         * @param string|null $type
         * @return null|UploadBase
         */
        public static function createFromRequest( &$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;
                Hooks::run( '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;
                }

                /** @var UploadBase $handler */
                $handler = new $className;

                $handler->initializeFromRequest( $request );

                return $handler;
        }

        /**
         * Check whether a request if valid for this handler
         * @param WebRequest $request
         * @return bool
         */
        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 string $name The desired destination name
         * @param string $tempPath The temporary path
         * @param int $fileSize The file size
         * @param bool $removeTempFile (false) remove the temporary file?
         * @throws MWException
         */
        public function initializePathInfo( $name, $tempPath, $fileSize, $removeTempFile = false ) {
                $this->mDesiredDestName = $name;
                if ( FileBackend::isStoragePath( $tempPath ) ) {
                        throw new MWException( __METHOD__ . " given storage path `$tempPath`." );
                }
                $this->mTempPath = $tempPath;
                $this->mFileSize = $fileSize;
                $this->mRemoveTempFile = $removeTempFile;
        }

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

        /**
         * Fetch the file. Usually a no-op
         * @return Status
         */
        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 int
         */
        public function getFileSize() {
                return $this->mFileSize;
        }

        /**
         * Get the base 36 SHA1 of the file
         * @return string
         */
        public function getTempFileSha1Base36() {
                return FSFile::getSha1Base36FromPath( $this->mTempPath );
        }

        /**
         * @param string $srcPath The source path
         * @return string|bool The real path if it was a virtual URL Returns false on failure
         */
        function getRealPath( $srcPath ) {
                $repo = RepoGroup::singleton()->getLocalRepo();
                if ( $repo->isVirtualUrl( $srcPath ) ) {
                        /** @todo Just make uploads work with storage paths UploadFromStash
                         *  loads files via virtual URLs.
                         */
                        $tmpFile = $repo->getLocalCopy( $srcPath );
                        if ( $tmpFile ) {
                                $tmpFile->bind( $this ); // keep alive with $this
                        }
                        $path = $tmpFile ? $tmpFile->getPath() : false;
                } else {
                        $path = $srcPath;
                }

                return $path;
        }

        /**
         * Verify whether the upload is sane.
         * @return mixed Const 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 ( !Hooks::run( '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
         */
        public 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.
         *
         * @note Only checks that it is not an evil MIME. The "does it have
         *  correct extension given its MIME type?" check is in verifyFile.
         *  in `verifyFile()` that MIME type and file extension correlate.
         * @param string $mime Representing the MIME
         * @return mixed True if the file is verified, an array otherwise
         */
        protected function verifyMimeType( $mime ) {
                global $wgVerifyMimeType;
                if ( $wgVerifyMimeType ) {
                        wfDebug( "mime: <$mime> extension: <{$this->mFinalExtension}>\n" );
                        global $wgMimeTypeBlacklist;
                        if ( $this->checkFileExtension( $mime, $wgMimeTypeBlacklist ) ) {

                                return array( 'filetype-badmime', $mime );
                        }

                        # Check what Internet Explorer would detect
                        $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() {
                global $wgVerifyMimeType, $wgDisableUploadScriptChecks;

                $status = $this->verifyPartialFile();
                if ( $status !== true ) {

                        return $status;
                }

                $this->mFileProps = FSFile::getPropsFromPath( $this->mTempPath, $this->mFinalExtension );
                $mime = $this->mFileProps['mime'];

                if ( $wgVerifyMimeType ) {
                        # 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 for htmlish code and javascript
                if ( !$wgDisableUploadScriptChecks ) {
                        if ( $this->mFinalExtension == 'svg' || $mime == 'image/svg+xml' ) {
                                $svgStatus = $this->detectScriptInSvg( $this->mTempPath, false );
                                if ( $svgStatus !== false ) {

                                        return $svgStatus;
                                }
                        }
                }

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

                                return reset( $errors );
                        }
                }

                Hooks::run( 'UploadVerifyFile', array( $this, $mime, &$status ) );
                if ( $status !== true ) {

                        return $status;
                }

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

                return true;
        }

        /**
         * A verification routine suitable for partial files
         *
         * Runs the blacklist checks, but not any checks that may
         * assume the entire file is present.
         *
         * @return mixed True for valid or array with error message key.
         */
        protected function verifyPartialFile() {
                global $wgAllowJavaUploads, $wgDisableUploadScriptChecks;

                # getTitle() sets some internal parameters like $this->mFinalExtension
                $this->getTitle();

                $this->mFileProps = FSFile::getPropsFromPath( $this->mTempPath, $this->mFinalExtension );

                # 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 ( !$wgDisableUploadScriptChecks ) {
                        if ( self::detectScript( $this->mTempPath, $mime, $this->mFinalExtension ) ) {

                                return array( 'uploadscripted' );
                        }
                        if ( $this->mFinalExtension == 'svg' || $mime == 'image/svg+xml' ) {
                                $svgStatus = $this->detectScriptInSvg( $this->mTempPath, true );
                                if ( $svgStatus !== false ) {

                                        return $svgStatus;
                                }
                        }
                }

                # Check for Java applets, which if uploaded can bypass cross-site
                # restrictions.
                if ( !$wgAllowJavaUploads ) {
                        $this->mJavaDetected = false;
                        $zipStatus = ZipDirectoryReader::read( $this->mTempPath,
                                array( $this, 'zipEntryCallback' ) );
                        if ( !$zipStatus->isOK() ) {
                                $errors = $zipStatus->getErrorsArray();
                                $error = reset( $errors );
                                if ( $error[0] !== 'zip-wrong-format' ) {

                                        return $error;
                                }
                        }
                        if ( $this->mJavaDetected ) {

                                return array( 'uploadjava' );
                        }
                }

                # Scan the uploaded file for viruses
                $virus = $this->detectVirus( $this->mTempPath );
                if ( $virus ) {

                        return array( 'uploadvirus', $virus );
                }


                return true;
        }

        /**
         * Callback for ZipDirectoryReader to detect Java class files.
         *
         * @param array $entry
         */
        function zipEntryCallback( $entry ) {
                $names = array( $entry['name'] );

                // If there is a null character, cut off the name at it, because JDK's
                // ZIP_GetEntry() uses strcmp() if the name hashes match. If a file name
                // were constructed which had ".class\0" followed by a string chosen to
                // make the hash collide with the truncated name, that file could be
                // returned in response to a request for the .class file.
                $nullPos = strpos( $entry['name'], "\000" );
                if ( $nullPos !== false ) {
                        $names[] = substr( $entry['name'], 0, $nullPos );
                }

                // If there is a trailing slash in the file name, we have to strip it,
                // because that's what ZIP_GetEntry() does.
                if ( preg_grep( '!\.class/?$!', $names ) ) {
                        $this->mJavaDetected = true;
                }
        }

        /**
         * Alias for verifyTitlePermissions. The function was originally
         * 'verifyPermissions', but that suggests it's checking the user, when it's
         * really checking the title + user combination.
         *
         * @param User $user 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 ) {
                return $this->verifyTitlePermissions( $user );
        }

        /**
         * 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 $user 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 verifyTitlePermissions( $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( 'create', $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( $overwriteError );
                }

                return true;
        }

        /**
         * Check for non fatal problems with the file.
         *
         * This should not assume that mTempPath is set.
         *
         * @return array Array of warnings
         */
        public function checkWarnings() {
                global $wgLang;

                $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'] = $filename;
                        // Debugging for bug 62241
                        wfDebugLog( 'upload', "Filename: '$filename', mDesiredDestName: "
                                . "'$this->mDesiredDestName', comparableName: '$comparableName'" );
                }

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

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

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

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

                // Check dupes against existing files
                $hash = $this->getTempFileSha1Base36();
                $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 ) {
                        if ( $archivedImage->userCan( File::DELETED_FILE ) ) {
                                $warnings['duplicate-archive'] = $archivedImage->getName();
                        } else {
                                $warnings['duplicate-archive'] = '';
                        }
                }


                return $warnings;
        }

        /**
         * Really perform the upload. Stores the file in the local repo, watches
         * if necessary and runs the UploadComplete hook.
         *
         * @param string $comment
         * @param string $pageText
         * @param bool $watch
         * @param User $user
         *
         * @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 ) {
                                WatchAction::doWatch(
                                        $this->getLocalFile()->getTitle(),
                                        $user,
                                        WatchedItem::IGNORE_USER_RIGHTS
                                );
                        }
                        Hooks::run( 'UploadComplete', array( &$this ) );

                        $this->postProcessUpload();
                }


                return $status;
        }

        /**
         * Perform extra steps after a successful upload.
         *
         * @since  1.25
         */
        public function postProcessUpload() {
                global $wgUploadThumbnailRenderMap;

                $jobs = array();

                $sizes = $wgUploadThumbnailRenderMap;
                rsort( $sizes );

                $file = $this->getLocalFile();

                foreach ( $sizes as $size ) {
                        if ( $file->isVectorized()
                                || $file->getWidth() > $size ) {
                                        $jobs[] = new ThumbnailRenderJob( $file->getTitle(), array(
                                                'transformParams' => array( 'width' => $size ),
                                        ) );
                        }
                }

                if ( $jobs ) {
                        JobQueueGroup::singleton()->push( $jobs );
                }
        }

        /**
         * 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;
                }
                /* Assume that if a user specified File:Something.jpg, this is an error
                 * and that the namespace prefix needs to be stripped of.
                 */
                $title = Title::newFromText( $this->mDesiredDestName );
                if ( $title && $title->getNamespace() == NS_FILE ) {
                        $this->mFilteredName = $title->getDBkey();
                } else {
                        $this->mFilteredName = $this->mDesiredDestName;
                }

                # oi_archive_name is max 255 bytes, which include a timestamp and an
                # exclamation mark, so restrict file name to 240 bytes.
                if ( strlen( $this->mFilteredName ) > 240 ) {
                        $this->mTitleError = self::FILENAME_TOO_LONG;
                        $this->mTitle = null;

                        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->mFilteredName );
                /* 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;
                        $this->mTitle = null;

                        return $this->mTitle;
                }
                $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;
                        $this->mTitle = null;

                        return $this->mTitle;
                } elseif ( $blackListedExtensions ||
                        ( $wgCheckFileExtensions && $wgStrictFileExtensions &&
                                !$this->checkFileExtension( $this->mFinalExtension, $wgFileExtensions ) )
                ) {
                        $this->mBlackListedExtensions = $blackListedExtensions;
                        $this->mTitleError = self::FILETYPE_BADTYPE;
                        $this->mTitle = null;

                        return $this->mTitle;
                }

                // Windows may be broken with special characters, see bug 1780
                if ( !preg_match( '/^[\x0-\x7f]*$/', $nt->getText() )
                        && !RepoGroup::singleton()->getLocalRepo()->backendSupportsUnicodePaths()
                ) {
                        $this->mTitleError = self::WINDOWS_NONASCII_FILENAME;
                        $this->mTitle = null;

                        return $this->mTitle;
                }

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

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

                        return $this->mTitle;
                }

                $this->mTitle = $nt;

                return $this->mTitle;
        }

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

                return $this->mLocalFile;
        }

        /**
         * 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 database.
         * This method returns the file object, which also has a 'fileKey' property
         * which can be passed through a form or API request to find this stashed
         * file again.
         *
         * @param User $user
         * @return UploadStashFile Stashed file
         */
        public function stashFile( User $user = null ) {
                // was stashSessionFile

                $stash = RepoGroup::singleton()->getLocalRepo()->getUploadStash( $user );
                $file = $stash->stashFile( $this->mTempPath, $this->getSourceType() );
                $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 stashFile().
         *
         * @return string File key
         */
        public function stashFileGetKey() {
                return $this->stashFile()->getFileKey();
        }

        /**
         * alias for stashFileGetKey, for backwards compatibility
         *
         * @return string File key
         */
        public function stashSession() {
                return $this->stashFileGetKey();
        }

        /**
         * 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.
         *
         * @param string $filename
         * @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 string $ext
         * @param array $list
         * @return bool
         */
        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 array $ext
         * @param array $list
         * @return bool
         */
        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 string $mime The MIME type of the uploaded file
         * @param string $extension The filename extension that the file is to be served with
         * @return bool
         */
        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 ) {
                        if ( $magic->getTypesForExtension( $extension ) !== null ) {
                                wfDebug( __METHOD__ . ": No extension known for $mime, but we know a mime for $extension\n" );

                                return false;
                        } else {
                                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 ImageMagick 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 string $file Pathname to the temporary upload file
         * @param string $mime The MIME type of the file
         * @param string $extension The extension of the file
         * @return bool 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 );

                /** @todo FIXME: Convert from UTF-16 if necessary! */
                wfDebug( __METHOD__ . ": checking for embedded scripts and HTML stuff\n" );

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

                        return true;
                }

                // Some browsers will interpret obscure xml encodings as UTF-8, while
                // PHP/expat will interpret the given encoding in the xml declaration (bug 47304)
                if ( $extension == 'svg' || strpos( $mime, 'image/svg' ) === 0 ) {
                        if ( self::checkXMLEncodingMissmatch( $file ) ) {

                                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 ) ) {
                                wfDebug( __METHOD__ . ": found something that may make it be mistaken for html: $tag\n" );

                                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 ) ) {
                        wfDebug( __METHOD__ . ": found script types\n" );

                        return true;
                }

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

                        return true;
                }

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

                        return true;
                }

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

                return false;
        }

        /**
         * Check a whitelist of xml encodings that are known not to be interpreted differently
         * by the server's xml parser (expat) and some common browsers.
         *
         * @param string $file Pathname to the temporary upload file
         * @return bool True if the file contains an encoding that could be misinterpreted
         */
        public static function checkXMLEncodingMissmatch( $file ) {
                global $wgSVGMetadataCutoff;
                $contents = file_get_contents( $file, false, null, -1, $wgSVGMetadataCutoff );
                $encodingRegex = '!encoding[ \t\n\r]*=[ \t\n\r]*[\'"](.*?)[\'"]!si';

                if ( preg_match( "!<\?xml\b(.*?)\?>!si", $contents, $matches ) ) {
                        if ( preg_match( $encodingRegex, $matches[1], $encMatch )
                                && !in_array( strtoupper( $encMatch[1] ), self::$safeXmlEncodings )
                        ) {
                                wfDebug( __METHOD__ . ": Found unsafe XML encoding '{$encMatch[1]}'\n" );

                                return true;
                        }
                } elseif ( preg_match( "!<\?xml\b!si", $contents ) ) {
                        // Start of XML declaration without an end in the first $wgSVGMetadataCutoff
                        // bytes. There shouldn't be a legitimate reason for this to happen.
                        wfDebug( __METHOD__ . ": Unmatched XML declaration start\n" );

                        return true;
                } elseif ( substr( $contents, 0, 4 ) == "\x4C\x6F\xA7\x94" ) {
                        // EBCDIC encoded XML
                        wfDebug( __METHOD__ . ": EBCDIC Encoded XML\n" );

                        return true;
                }

                // It's possible the file is encoded with multi-byte encoding, so re-encode attempt to
                // detect the encoding in case is specifies an encoding not whitelisted in self::$safeXmlEncodings
                $attemptEncodings = array( 'UTF-16', 'UTF-16BE', 'UTF-32', 'UTF-32BE' );
                foreach ( $attemptEncodings as $encoding ) {
                        wfSuppressWarnings();
                        $str = iconv( $encoding, 'UTF-8', $contents );
                        wfRestoreWarnings();
                        if ( $str != '' && preg_match( "!<\?xml\b(.*?)\?>!si", $str, $matches ) ) {
                                if ( preg_match( $encodingRegex, $matches[1], $encMatch )
                                        && !in_array( strtoupper( $encMatch[1] ), self::$safeXmlEncodings )
                                ) {
                                        wfDebug( __METHOD__ . ": Found unsafe XML encoding '{$encMatch[1]}'\n" );

                                        return true;
                                }
                        } elseif ( $str != '' && preg_match( "!<\?xml\b!si", $str ) ) {
                                // Start of XML declaration without an end in the first $wgSVGMetadataCutoff
                                // bytes. There shouldn't be a legitimate reason for this to happen.
                                wfDebug( __METHOD__ . ": Unmatched XML declaration start\n" );

                                return true;
                        }
                }

                return false;
        }

        /**
         * @param string $filename
         * @param bool $partial
         * @return mixed False of the file is verified (does not contain scripts), array otherwise.
         */
        protected function detectScriptInSvg( $filename, $partial ) {
                $this->mSVGNSError = false;
                $check = new XmlTypeCheck(
                        $filename,
                        array( $this, 'checkSvgScriptCallback' ),
                        true,
                        array( 'processing_instruction_handler' => 'UploadBase::checkSvgPICallback' )
                );
                if ( $check->wellFormed !== true ) {
                        // Invalid xml (bug 58553)
                        // But only when non-partial (bug 65724)
                        return $partial ? false : array( 'uploadinvalidxml' );
                } elseif ( $check->filterMatch ) {
                        if ( $this->mSVGNSError ) {
                                return array( 'uploadscriptednamespace', $this->mSVGNSError );
                        }

                        return array( 'uploadscripted' );
                }

                return false;
        }

        /**
         * Callback to filter SVG Processing Instructions.
         * @param string $target Processing instruction name
         * @param string $data Processing instruction attribute and value
         * @return bool (true if the filter identified something bad)
         */
        public static function checkSvgPICallback( $target, $data ) {
                // Don't allow external stylesheets (bug 57550)
                if ( preg_match( '/xml-stylesheet/i', $target ) ) {
                        return true;
                }

                return false;
        }

        /**
         * @todo Replace this with a whitelist filter!
         * @param string $element
         * @param array $attribs
         * @return bool
         */
        public function checkSvgScriptCallback( $element, $attribs, $data = null ) {

                list( $namespace, $strippedElement ) = $this->splitXmlNamespace( $element );

                // We specifically don't include:
                // http://www.w3.org/1999/xhtml (bug 60771)
                static $validNamespaces = array(
                        '',
                        'adobe:ns:meta/',
                        'http://creativecommons.org/ns#',
                        'http://inkscape.sourceforge.net/dtd/sodipodi-0.dtd',
                        'http://ns.adobe.com/adobeillustrator/10.0/',
                        'http://ns.adobe.com/adobesvgviewerextensions/3.0/',
                        'http://ns.adobe.com/extensibility/1.0/',
                        'http://ns.adobe.com/flows/1.0/',
                        'http://ns.adobe.com/illustrator/1.0/',
                        'http://ns.adobe.com/imagereplacement/1.0/',
                        'http://ns.adobe.com/pdf/1.3/',
                        'http://ns.adobe.com/photoshop/1.0/',
                        'http://ns.adobe.com/saveforweb/1.0/',
                        'http://ns.adobe.com/variables/1.0/',
                        'http://ns.adobe.com/xap/1.0/',
                        'http://ns.adobe.com/xap/1.0/g/',
                        'http://ns.adobe.com/xap/1.0/g/img/',
                        'http://ns.adobe.com/xap/1.0/mm/',
                        'http://ns.adobe.com/xap/1.0/rights/',
                        'http://ns.adobe.com/xap/1.0/stype/dimensions#',
                        'http://ns.adobe.com/xap/1.0/stype/font#',
                        'http://ns.adobe.com/xap/1.0/stype/manifestitem#',
                        'http://ns.adobe.com/xap/1.0/stype/resourceevent#',
                        'http://ns.adobe.com/xap/1.0/stype/resourceref#',
                        'http://ns.adobe.com/xap/1.0/t/pg/',
                        'http://purl.org/dc/elements/1.1/',
                        'http://purl.org/dc/elements/1.1',
                        'http://schemas.microsoft.com/visio/2003/svgextensions/',
                        'http://sodipodi.sourceforge.net/dtd/sodipodi-0.dtd',
                        'http://taptrix.com/inkpad/svg_extensions',
                        'http://web.resource.org/cc/',
                        'http://www.freesoftware.fsf.org/bkchem/cdml',
                        'http://www.inkscape.org/namespaces/inkscape',
                        'http://www.opengis.net/gml',
                        'http://www.w3.org/1999/02/22-rdf-syntax-ns#',
                        'http://www.w3.org/2000/svg',
                        'http://www.w3.org/tr/rec-rdf-syntax/',
                );

                if ( !in_array( $namespace, $validNamespaces ) ) {
                        wfDebug( __METHOD__ . ": Non-svg namespace '$namespace' in uploaded file.\n" );
                        /** @todo Return a status object to a closure in XmlTypeCheck, for MW1.21+ */
                        $this->mSVGNSError = $namespace;

                        return true;
                }

                /*
                 * check for elements that can contain javascript
                 */
                if ( $strippedElement == 'script' ) {
                        wfDebug( __METHOD__ . ": Found script element '$element' in uploaded file.\n" );

                        return true;
                }

                # e.g., <svg xmlns="http://www.w3.org/2000/svg">
                #  <handler xmlns:ev="http://www.w3.org/2001/xml-events" ev:event="load">alert(1)</handler> </svg>
                if ( $strippedElement == 'handler' ) {
                        wfDebug( __METHOD__ . ": Found scriptable element '$element' in uploaded file.\n" );

                        return true;
                }

                # SVG reported in Feb '12 that used xml:stylesheet to generate javascript block
                if ( $strippedElement == 'stylesheet' ) {
                        wfDebug( __METHOD__ . ": Found scriptable element '$element' in uploaded file.\n" );

                        return true;
                }

                # Block iframes, in case they pass the namespace check
                if ( $strippedElement == 'iframe' ) {
                        wfDebug( __METHOD__ . ": iframe in uploaded file.\n" );

                        return true;
                }

                # Check <style> css
                if ( $strippedElement == 'style'
                        && self::checkCssFragment( Sanitizer::normalizeCss( $data ) )
                ) {
                        wfDebug( __METHOD__ . ": hostile css in style element.\n" );
                        return true;
                }

                foreach ( $attribs as $attrib => $value ) {
                        $stripped = $this->stripXmlNamespace( $attrib );
                        $value = strtolower( $value );

                        if ( substr( $stripped, 0, 2 ) == 'on' ) {
                                wfDebug( __METHOD__
                                        . ": Found event-handler attribute '$attrib'='$value' in uploaded file.\n" );

                                return true;
                        }

                        # href with non-local target (don't allow http://, javascript:, etc)
                        if ( $stripped == 'href'
                                && strpos( $value, 'data:' ) !== 0
                                && strpos( $value, '#' ) !== 0
                        ) {
                                if ( !( $strippedElement === 'a'
                                        && preg_match( '!^https?://!im', $value ) )
                                ) {
                                        wfDebug( __METHOD__ . ": Found href attribute <$strippedElement "
                                                . "'$attrib'='$value' in uploaded file.\n" );

                                        return true;
                                }
                        }

                        # href with embedded svg as target
                        if ( $stripped == 'href' && preg_match( '!data:[^,]*image/svg[^,]*,!sim', $value ) ) {
                                wfDebug( __METHOD__ . ": Found href to embedded svg "
                                        . "\"<$strippedElement '$attrib'='$value'...\" in uploaded file.\n" );

                                return true;
                        }

                        # href with embedded (text/xml) svg as target
                        if ( $stripped == 'href' && preg_match( '!data:[^,]*text/xml[^,]*,!sim', $value ) ) {
                                wfDebug( __METHOD__ . ": Found href to embedded svg "
                                        . "\"<$strippedElement '$attrib'='$value'...\" in uploaded file.\n" );

                                return true;
                        }

                        # Change href with animate from (http://html5sec.org/#137). This doesn't seem
                        # possible without embedding the svg, but filter here in case.
                        if ( $stripped == 'from'
                                && $strippedElement === 'animate'
                                && !preg_match( '!^https?://!im', $value )
                        ) {
                                wfDebug( __METHOD__ . ": Found animate that might be changing href using from "
                                        . "\"<$strippedElement '$attrib'='$value'...\" in uploaded file.\n" );

                                return true;
                        }

                        # use set/animate to add event-handler attribute to parent
                        if ( ( $strippedElement == 'set' || $strippedElement == 'animate' )
                                && $stripped == 'attributename'
                                && substr( $value, 0, 2 ) == 'on'
                        ) {
                                wfDebug( __METHOD__ . ": Found svg setting event-handler attribute with "
                                        . "\"<$strippedElement $stripped='$value'...\" in uploaded file.\n" );

                                return true;
                        }

                        # use set to add href attribute to parent element
                        if ( $strippedElement == 'set'
                                && $stripped == 'attributename'
                                && strpos( $value, 'href' ) !== false
                        ) {
                                wfDebug( __METHOD__ . ": Found svg setting href attribute '$value' in uploaded file.\n" );

                                return true;
                        }

                        # use set to add a remote / data / script target to an element
                        if ( $strippedElement == 'set'
                                && $stripped == 'to'
                                && preg_match( '!(http|https|data|script):!sim', $value )
                        ) {
                                wfDebug( __METHOD__ . ": Found svg setting attribute to '$value' in uploaded file.\n" );

                                return true;
                        }

                        # use handler attribute with remote / data / script
                        if ( $stripped == 'handler' && preg_match( '!(http|https|data|script):!sim', $value ) ) {
                                wfDebug( __METHOD__ . ": Found svg setting handler with remote/data/script "
                                        . "'$attrib'='$value' in uploaded file.\n" );

                                return true;
                        }

                        # use CSS styles to bring in remote code
                        if ( $stripped == 'style'
                                && self::checkCssFragment( Sanitizer::normalizeCss( $value ) )
                        ) {
                                wfDebug( __METHOD__ . ": Found svg setting a style with "
                                        . "remote url '$attrib'='$value' in uploaded file.\n" );
                                return true;
                        }

                        # Several attributes can include css, css character escaping isn't allowed
                        $cssAttrs = array( 'font', 'clip-path', 'fill', 'filter', 'marker',
                                'marker-end', 'marker-mid', 'marker-start', 'mask', 'stroke' );
                        if ( in_array( $stripped, $cssAttrs )
                                && self::checkCssFragment( $value )
                        ) {
                                wfDebug( __METHOD__ . ": Found svg setting a style with "
                                        . "remote url '$attrib'='$value' in uploaded file.\n" );
                                return true;
                        }

                        # image filters can pull in url, which could be svg that executes scripts
                        if ( $strippedElement == 'image'
                                && $stripped == 'filter'
                                && preg_match( '!url\s*\(!sim', $value )
                        ) {
                                wfDebug( __METHOD__ . ": Found image filter with url: "
                                        . "\"<$strippedElement $stripped='$value'...\" in uploaded file.\n" );

                                return true;
                        }
                }

                return false; //No scripts detected
        }

        /**
         * Check a block of CSS or CSS fragment for anything that looks like
         * it is bringing in remote code.
         * @param string $value a string of CSS
         * @param bool $propOnly only check css properties (start regex with :)
         * @return bool true if the CSS contains an illegal string, false if otherwise
         */
        private static function checkCssFragment( $value ) {

                # Forbid external stylesheets, for both reliability and to protect viewer's privacy
                if ( strpos( $value, '@import' ) !== false ) {
                        return true;
                }

                # We allow @font-face to embed fonts with data: urls, so we snip the string
                # 'url' out so this case won't match when we check for urls below
                $pattern = '!(@font-face\s*{[^}]*src:)url(\("data:;base64,)!im';
                $value = preg_replace( $pattern, '$1$2', $value );

                # Check for remote and executable CSS. Unlike in Sanitizer::checkCss, the CSS
                # properties filter and accelerator don't seem to be useful for xss in SVG files.
                # Expression and -o-link don't seem to work either, but filtering them here in case.
                # Additionally, we catch remote urls like url("http:..., url('http:..., url(http:...,
                # but not local ones such as url("#..., url('#..., url(#....
                if ( preg_match( '!expression
                                | -o-link\s*:
                                | -o-link-source\s*:
                                | -o-replace\s*:!imx', $value ) ) {
                        return true;
                }

                if ( preg_match_all(
                                "!(\s*(url|image|image-set)\s*\(\s*[\"']?\s*[^#]+.*?\))!sim",
                                $value,
                                $matches
                        ) !== 0
                ) {
                        # TODO: redo this in one regex. Until then, url("#whatever") matches the first
                        foreach ( $matches[1] as $match ) {
                                if ( !preg_match( "!\s*(url|image|image-set)\s*\(\s*(#|'#|\"#)!im", $match ) ) {
                                        return true;
                                }
                        }
                }

                if ( preg_match( '/[\000-\010\013\016-\037\177]/', $value ) ) {
                        return true;
                }

                return false;
        }

        /**
         * Divide the element name passed by the xml parser to the callback into URI and prifix.
         * @param string $element
         * @return array Containing the namespace URI and prefix
         */
        private static function splitXmlNamespace( $element ) {
                // 'http://www.w3.org/2000/svg:script' -> array( 'http://www.w3.org/2000/svg', 'script' )
                $parts = explode( ':', strtolower( $element ) );
                $name = array_pop( $parts );
                $ns = implode( ':', $parts );

                return array( $ns, $name );
        }

        /**
         * @param string $name
         * @return string
         */
        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 string $file 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 wfMessage( 'virus-unknownscanner' )->text() . " $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 = wfShellExecWithStderr( $command, $exitCode );

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

                /* NB: AV_NO_VIRUS is 0 but AV_SCAN_FAILED is false,
                 * so we need the strict equalities === and thus can't use a switch here
                 */
                if ( $mappedCode === AV_SCAN_FAILED ) {
                        # scan failed (code was mapped to false by $exitCodeMap)
                        wfDebug( __METHOD__ . ": failed to scan $file (code $exitCode).\n" );

                        $output = $wgAntivirusRequired
                                ? wfMessage( 'virus-scanfailed', array( $exitCode ) )->text()
                                : null;
                } elseif ( $mappedCode === AV_SCAN_ABORTED ) {
                        # scan failed because filetype is unknown (probably imune)
                        wfDebug( __METHOD__ . ": unsupported file type $file (code $exitCode).\n" );
                        $output = null;
                } elseif ( $mappedCode === AV_NO_VIRUS ) {
                        # no virus found
                        wfDebug( __METHOD__ . ": file passed virus scan.\n" );
                        $output = 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 there's an overwrite conflict and, if so, if restrictions
         * forbid this user from performing the upload.
         *
         * @param User $user
         *
         * @return mixed True on success, array 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 array( 'fileexists-forbidden', $file->getName() );
                        } 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 array( 'fileexists-shared-forbidden', $file->getName() );
                }

                return true;
        }

        /**
         * Check if a user is the last uploader
         *
         * @param User $user
         * @param string $img Image name
         * @return bool
         */
        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
                                );
                        }
                }

                // Check for files with the same name but a different extension
                $similarFiles = RepoGroup::singleton()->getLocalRepo()->findFilesByPrefix(
                        "{$partname}.", 1 );
                if ( count( $similarFiles ) ) {
                        return array(
                                'warning' => 'exists-normalized',
                                'file' => $file,
                                'normalizedFile' => $similarFiles[0],
                        );
                }

                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
         * @param string $filename
         * @return bool
         */
        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 ApiResult $result
         * @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;
        }

        /**
         * @param array $error
         * @return Status
         */
        public function convertVerifyErrorToStatus( $error ) {
                $code = $error['status'];
                unset( $code['status'] );

                return Status::newFatal( $this->getVerificationErrorCode( $code ), $error );
        }

        /**
         * @param null|string $forType
         * @return int
         */
        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 );
                }
        }

        /**
         * Get the current status of a chunked upload (used for polling)
         *
         * The value will be read from cache.
         *
         * @param User $user
         * @param string $statusKey
         * @return Status[]|bool
         */
        public static function getSessionStatus( User $user, $statusKey ) {
                $key = wfMemcKey( 'uploadstatus', $user->getId() ?: md5( $user->getName() ), $statusKey );

                return wfGetCache( CACHE_ANYTHING )->get( $key );
        }

        /**
         * Set the current status of a chunked upload (used for polling)
         *
         * The value will be set in cache for 1 day
         *
         * @param User $user
         * @param string $statusKey
         * @param array|bool $value
         * @return void
         */
        public static function setSessionStatus( User $user, $statusKey, $value ) {
                $key = wfMemcKey( 'uploadstatus', $user->getId() ?: md5( $user->getName() ), $statusKey );

                $cache = wfGetCache( CACHE_ANYTHING );
                if ( $value === false ) {
                        $cache->delete( $key );
                } else {
                        $cache->set( $key, $value, 86400 );
                }
        }
}