[lhc/web/wiklou.git] / includes / upload / UploadStash.php

<?php
/** 
 * UploadStash is intended to accomplish a few things:
 *   - enable applications to temporarily stash files without publishing them to the wiki.
 *      - Several parts of MediaWiki do this in similar ways: UploadBase, UploadWizard, and FirefoggChunkedExtension
 *        And there are several that reimplement stashing from scratch, in idiosyncratic ways. The idea is to unify them all here.
 *        Mostly all of them are the same except for storing some custom fields, which we subsume into the data array.
 *   - enable applications to find said files later, as long as the session or temp files haven't been purged. 
 *   - enable the uploading user (and *ONLY* the uploading user) to access said files, and thumbnails of said files, via a URL.
 *     We accomplish this by making the session serve as a URL->file mapping, on the assumption that nobody else can access 
 *     the session, even the uploading user. See SpecialUploadStash, which implements a web interface to some files stored this way.
 *
 */
class UploadStash {
        // Format of the key for files -- has to be suitable as a filename itself in some cases.
        // This should encompass a sha1 content hash in hex (new style), or an integer (old style), 
        // and also thumbnails with prepended strings like "120px-". 
        // The file extension should not be part of the key.
        const KEY_FORMAT_REGEX = '/^[\w-]+$/';

        // repository that this uses to store temp files
        protected $repo; 
        
        // array of initialized objects obtained from session (lazily initialized upon getFile())
        private $files = array();  

        // TODO: Once UploadBase starts using this, switch to use these constants rather than UploadBase::SESSION*
        // const SESSION_VERSION = 2;
        // const SESSION_KEYNAME = 'wsUploadData';

        /**
         * Represents the session which contains temporarily stored files.
         * Designed to be compatible with the session stashing code in UploadBase (should replace it eventually)
         *
         * @param $repo FileRepo: optional -- repo in which to store files. Will choose LocalRepo if not supplied.
         */
        public function __construct( $repo = null ) { 

                if ( is_null( $repo ) ) {
                        $repo = RepoGroup::singleton()->getLocalRepo();
                }

                $this->repo = $repo;

                if ( ! isset( $_SESSION ) ) {
                        throw new UploadStashNotAvailableException( 'no session variable' );
                }

                if ( !isset( $_SESSION[UploadBase::SESSION_KEYNAME] ) ) {
                        $_SESSION[UploadBase::SESSION_KEYNAME] = array();
                }
                
        }

        /**
         * Get a file and its metadata from the stash.
         * May throw exception if session data cannot be parsed due to schema change, or key not found.
         *
         * @param $key Integer: key
         * @throws UploadStashFileNotFoundException
         * @throws UploadStashBadVersionException
         * @return UploadStashFile
         */
        public function getFile( $key ) {
                if ( ! preg_match( self::KEY_FORMAT_REGEX, $key ) ) {
                        throw new UploadStashBadPathException( "key '$key' is not in a proper format" );
                } 
 
                if ( !isset( $this->files[$key] ) ) {
                        if ( !isset( $_SESSION[UploadBase::SESSION_KEYNAME][$key] ) ) {
                                throw new UploadStashFileNotFoundException( "key '$key' not found in stash" );
                        }

                        $data = $_SESSION[UploadBase::SESSION_KEYNAME][$key];
                        // guards against PHP class changing while session data doesn't
                        if ($data['version'] !== UploadBase::SESSION_VERSION ) {
                                throw new UploadStashBadVersionException( $data['version'] . " does not match current version " . UploadBase::SESSION_VERSION );
                        }
                
                        // separate the stashData into the path, and then the rest of the data
                        $path = $data['mTempPath'];
                        unset( $data['mTempPath'] );

                        $file = new UploadStashFile( $this, $this->repo, $path, $key, $data );
                        
                        $this->files[$key] = $file;

                }
                return $this->files[$key];
        }

        /**
         * Stash a file in a temp directory and record that we did this in the session, along with other metadata.
         * We store data in a flat key-val namespace because that's how UploadBase did it. This also means we have to
         * ensure that the key-val pairs in $data do not overwrite other required fields.
         *
         * @param $path String: path to file you want stashed
         * @param $data Array: optional, other data you want associated with the file. Do not use 'mTempPath', 'mFileProps', 'mFileSize', or 'version' as keys here
         * @param $key String: optional, unique key for this file in this session. Used for directory hashing when storing, otherwise not important
         * @throws UploadStashBadPathException
         * @throws UploadStashFileException
         * @return UploadStashFile: file, or null on failure
         */
        public function stashFile( $path, $data = array(), $key = null ) {
                if ( ! file_exists( $path ) ) {
                        wfDebug( "UploadStash: tried to stash file at '$path', but it doesn't exist\n" );
                        throw new UploadStashBadPathException( "path doesn't exist" );
                }
                $fileProps = File::getPropsFromPath( $path );

                // If no key was supplied, use content hash. Also has the nice property of collapsing multiple identical files
                // uploaded this session, which could happen if uploads had failed.
                if ( is_null( $key ) ) {
                        $key = $fileProps['sha1'];
                }

                if ( ! preg_match( self::KEY_FORMAT_REGEX, $key ) ) {
                        throw new UploadStashBadPathException( "key '$key' is not in a proper format" );
                } 

                // if not already in a temporary area, put it there 
                $status = $this->repo->storeTemp( basename( $path ), $path );
                if( ! $status->isOK() ) {
                        // It is a convention in MediaWiki to only return one error per API exception, even if multiple errors
                        // are available. We use reset() to pick the "first" thing that was wrong, preferring errors to warnings.
                        // This is a bit lame, as we may have more info in the $status and we're throwing it away, but to fix it means
                        // redesigning API errors significantly.
                        // $status->value just contains the virtual URL (if anything) which is probably useless to the caller
                        $error = reset( $status->getErrorsArray() );
                        if ( ! count( $error ) ) {
                                $error = reset( $status->getWarningsArray() );
                                if ( ! count( $error ) ) {
                                        $error = array( 'unknown', 'no error recorded' );
                                }
                        }
                        throw new UploadStashFileException( "error storing file in '$path': " . implode( '; ', $error ) );
                }
                $stashPath = $status->value;
                                
                // required info we always store. Must trump any other application info in $data
                // 'mTempPath', 'mFileSize', and 'mFileProps' are arbitrary names
                // chosen for compatibility with UploadBase's way of doing this.
                $requiredData = array( 
                        'mTempPath' => $stashPath,
                        'mFileSize' => $fileProps['size'],
                        'mFileProps' => $fileProps,
                        'version' => UploadBase::SESSION_VERSION
                );

                // now, merge required info and extra data into the session. (The extra data changes from application to application.
                // UploadWizard wants different things than say FirefoggChunkedUpload.)
                $_SESSION[UploadBase::SESSION_KEYNAME][$key] = array_merge( $data, $requiredData );
                
                return $this->getFile( $key );
        }

}

class UploadStashFile extends UnregisteredLocalFile {
        private $sessionStash;
        private $sessionKey;
        private $sessionData;
        private $urlName;

        /**
         * A LocalFile wrapper around a file that has been temporarily stashed, so we can do things like create thumbnails for it
         * Arguably UnregisteredLocalFile should be handling its own file repo but that class is a bit retarded currently
         *
         * @param $stash UploadStash: useful for obtaining config, stashing transformed files
         * @param $repo FileRepo: repository where we should find the path
         * @param $path String: path to file
         * @param $key String: key to store the path and any stashed data under
         * @param $data String: any other data we want stored with this file
         * @throws UploadStashBadPathException
         * @throws UploadStashFileNotFoundException
         */
        public function __construct( $stash, $repo, $path, $key, $data ) { 
                $this->sessionStash = $stash;
                $this->sessionKey = $key;
                $this->sessionData = $data;

                // resolve mwrepo:// urls
                if ( $repo->isVirtualUrl( $path ) ) {
                        $path = $repo->resolveVirtualUrl( $path );      
                }

                // check if path appears to be sane, no parent traversals, and is in this repo's temp zone.
                $repoTempPath = $repo->getZonePath( 'temp' );
                if ( ( ! $repo->validateFilename( $path ) ) || 
                                ( strpos( $path, $repoTempPath ) !== 0 ) ) {
                        wfDebug( "UploadStash: tried to construct an UploadStashFile from a file that should already exist at '$path', but path is not valid\n" );
                        throw new UploadStashBadPathException( 'path is not valid' );
                }

                // check if path exists! and is a plain file.
                if ( ! $repo->fileExists( $path, FileRepo::FILES_ONLY ) ) {
                        wfDebug( "UploadStash: tried to construct an UploadStashFile from a file that should already exist at '$path', but path is not found\n" );
                        throw new UploadStashFileNotFoundException( 'cannot find path, or not a plain file' );
                }

                parent::__construct( false, $repo, $path, false );

                // we will be initializing from some tmpnam files that don't have extensions.
                // most of MediaWiki assumes all uploaded files have good extensions. So, we fix this.
                $this->name = basename( $this->path );
                $this->setExtension();

        }

        /**
         * A method needed by the file transforming and scaling routines in File.php
         * We do not necessarily care about doing the description at this point
         * However, we also can't return the empty string, as the rest of MediaWiki demands this (and calls to imagemagick
         * convert require it to be there)
         *
         * @return String: dummy value
         */
        public function getDescriptionUrl() {
                return $this->getUrl();
        }

        /**
         * Find or guess extension -- ensuring that our extension matches our mime type.
         * Since these files are constructed from php tempnames they may not start off 
         * with an extension.
         * This does not override getExtension() because things like getMimeType() already call getExtension(),
         * and that results in infinite recursion. So, we preemptively *set* the extension so getExtension() can find it.
         * For obvious reasons this should be called as early as possible, as part of initialization
         */
        public function setExtension() {        
                // Does this have an extension?
                $n = strrpos( $this->path, '.' );
                $extension = null;
                if ( $n !== false ) {
                        $extension = $n ? substr( $this->path, $n + 1 ) : '';
                } else {
                        // If not, assume that it should be related to the mime type of the original file.
                        //
                        // This entire thing is backwards -- we *should* just create an extension based on 
                        // the mime type of the transformed file, *after* transformation.  But File.php demands 
                        // to know the name of the transformed file before creating it. 
                        $mimeType = $this->getMimeType();
                        $extensions = explode( ' ', MimeMagic::singleton()->getExtensionsForType( $mimeType ) );
                        if ( count( $extensions ) ) { 
                                $extension = $extensions[0];    
                        }
                }

                if ( is_null( $extension ) ) {
                        throw new UploadStashFileException( "extension is null" );
                }

                $this->extension = parent::normalizeExtension( $extension );
        }

        /**
         * Get the path for the thumbnail (actually any transformation of this file)
         * The actual argument is the result of thumbName although we seem to have 
         * buggy code elsewhere that expects a boolean 'suffix'
         *
         * @param $thumbName String: name of thumbnail (e.g. "120px-123456.jpg" ), or false to just get the path
         * @return String: path thumbnail should take on filesystem, or containing directory if thumbname is false
         */
        public function getThumbPath( $thumbName = false ) { 
                $path = dirname( $this->path );
                if ( $thumbName !== false ) {
                        $path .= "/$thumbName";
                }
                return $path;
        }

        /**
         * Return the file/url base name of a thumbnail with the specified parameters
         *
         * @param $params Array: handler-specific parameters
         * @return String: base name for URL, like '120px-12345.jpg', or null if there is no handler
         */
        function thumbName( $params ) {
                if ( !$this->getHandler() ) {
                        return null;
                }
                $extension = $this->getExtension();
                list( $thumbExt, $thumbMime ) = $this->handler->getThumbType( $extension, $this->getMimeType(), $params );
                $thumbName = $this->getHandler()->makeParamString( $params ) . '-' . $this->getUrlName();
                if ( $thumbExt != $extension ) {
                        $thumbName .= ".$thumbExt";
                }
                return $thumbName;
        }

        /**
         * Helper function -- given a 'subpage', return the local URL e.g. /wiki/Special:UploadStash/subpage
         * @param {String} $subPage
         * @return {String} local URL for this subpage in the Special:UploadStash space. 
         */
        private function getSpecialUrl( $subPage ) {
                return SpecialPage::getTitleFor( 'UploadStash', $subPage )->getLocalURL();
        }


        /** 
         * Get a URL to access the thumbnail 
         * This is required because the model of how files work requires that 
         * the thumbnail urls be predictable. However, in our model the URL is not based on the filename
         * (that's hidden in the session)
         *
         * @param $thumbName String: basename of thumbnail file -- however, we don't want to use the file exactly
         * @return String: URL to access thumbnail, or URL with partial path
         */
        public function getThumbUrl( $thumbName = false ) { 
                return self::getSpecialUrl( $thumbName );
        }

        /** 
         * The basename for the URL, which we want to not be related to the filename.
         * Will also be used as the lookup key for a thumbnail file.
         *
         * @return String: base url name, like '120px-123456.jpg'
         */
        public function getUrlName() { 
                if ( ! $this->urlName ) {
                        $this->urlName = $this->sessionKey . '.' . $this->getExtension();
                }
                return $this->urlName;
        }

        /**
         * Return the URL of the file, if for some reason we wanted to download it
         * We tend not to do this for the original file, but we do want thumb icons
         *
         * @return String: url
         */
        public function getUrl() {
                if ( !isset( $this->url ) ) {
                        $this->url = self::getSpecialUrl( $this->getUrlName() );
                }
                return $this->url;
        }

        /**
         * Parent classes use this method, for no obvious reason, to return the path (relative to wiki root, I assume). 
         * But with this class, the URL is unrelated to the path.
         *
         * @return String: url
         */
        public function getFullUrl() { 
                return $this->getUrl();
        }


        /**
         * Getter for session key (the session-unique id by which this file's location & metadata is stored in the session)
         *
         * @return String: session key
         */
        public function getSessionKey() {
                return $this->sessionKey;
        }

        /**
         * Typically, transform() returns a ThumbnailImage, which you can think of as being the exact
         * equivalent of an HTML thumbnail on Wikipedia. So its URL is the full-size file, not the thumbnail's URL.
         *
         * Here we override transform() to stash the thumbnail file, and then 
         * provide a way to get at the stashed thumbnail file to extract properties such as its URL
         *
         * @param $params Array: parameters suitable for File::transform()
         * @param $flags Integer: bitmask, flags suitable for File::transform()
         * @return ThumbnailImage: with additional File thumbnailFile property
         */
        public function transform( $params, $flags = 0 ) { 

                // force it to get a thumbnail right away
                $flags |= self::RENDER_NOW;

                // returns a ThumbnailImage object containing the url and path. Note. NOT A FILE OBJECT.
                $thumb = parent::transform( $params, $flags );
                wfDebug( "UploadStash: generating thumbnail\n" );
                wfDebug( print_r( $thumb, 1 ) );
                $key = $this->thumbName($params);

                // remove extension, so it's stored in the session under '120px-123456'
                // this makes it uniform with the other session key for the original, '123456'
                $n = strrpos( $key, '.' );      
                if ( $n !== false ) {
                        $key = substr( $key, 0, $n );
                }

                // stash the thumbnail File, and provide our caller with a way to get at its properties
                $stashedThumbFile = $this->sessionStash->stashFile( $thumb->getPath(), array(), $key );
                $thumb->thumbnailFile = $stashedThumbFile;

                return $thumb;  

        }

        /**
         * Remove the associated temporary file
         * @return Status: success
         */
        public function remove() {
                return $this->repo->freeTemp( $this->path );
        }

}

class UploadStashNotAvailableException extends MWException {};
class UploadStashFileNotFoundException extends MWException {};
class UploadStashBadPathException extends MWException {};
class UploadStashBadVersionException extends MWException {};
class UploadStashFileException extends MWException {};