[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 db table 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 using a database table, with ownership checking as you might expect. See SpecialUploadStash, which 
 *     implements a web interface to some files stored this way.
 *
 * UploadStash represents the entire stash of temporary files.
 * UploadStashFile is a filestore for the actual physical disk files.
 * UploadFromStash extends UploadBase, and represents a single stashed file as it is moved from the stash to the regular file repository
 */
class UploadStash {

        // Format of the key for files -- has to be suitable as a filename itself (e.g. ab12cd34ef.jpg)
        const KEY_FORMAT_REGEX = '/^[\w-]+\.\w*$/';
        
        // When a given stashed file can't be loaded, wait for the slaves to catch up.  If they're more than MAX_LAG
        // behind, throw an exception instead. (at what point is broken better than slow?)
        const MAX_LAG = 30;

        // Age of the repository in hours.  That is, after how long will files be assumed abandoned and deleted?
        const REPO_AGE = 6;

        /**
         * repository that this uses to store temp files
         * public because we sometimes need to get a LocalFile within the same repo.
         *
         * @var LocalRepo
         */
        public $repo;

        // array of initialized repo objects
        protected $files = array();
        
        // cache of the file metadata that's stored in the database
        protected $fileMetadata = array();
        
        // fileprops cache
        protected $fileProps = array();
        
        // current user
        protected $user, $userId, $isLoggedIn;

        /**
         * Represents a temporary filestore, with metadata in the database.
         * Designed to be compatible with the session stashing code in UploadBase (should replace it eventually)
         *
         * @param $repo FileRepo
         */
        public function __construct( $repo, $user = null ) {
                // this might change based on wiki's configuration.
                $this->repo = $repo;
        
                // if a user was passed, use it. otherwise, attempt to use the global.
                // this keeps FileRepo from breaking when it creates an UploadStash object
                if( $user ) {
                        $this->user = $user;
                } else {
                        global $wgUser;
                        $this->user = $wgUser;
                }
                
                if( is_object($this->user) ) {
                        $this->userId = $this->user->getId();
                        $this->isLoggedIn = $this->user->isLoggedIn();
                }
        }

        /**
         * Get a file and its metadata from the stash.
         *
         * @param $key String: key under which file information is stored
         * @param $noAuth Boolean (optional) Don't check authentication. Used by maintenance scripts.
         * @throws UploadStashFileNotFoundException
         * @throws UploadStashNotLoggedInException
         * @throws UploadStashWrongOwnerException
         * @throws UploadStashBadPathException
         * @return UploadStashFile
         */
        public function getFile( $key, $noAuth = false ) {
                
                if ( ! preg_match( self::KEY_FORMAT_REGEX, $key ) ) {
                        throw new UploadStashBadPathException( "key '$key' is not in a proper format" );
                }
                
                if( !$noAuth ) {
                        if( !$this->isLoggedIn ) {
                                throw new UploadStashNotLoggedInException( __METHOD__ . ' No user is logged in, files must belong to users' );
                        }
                }
                
                $dbr = $this->repo->getSlaveDb();
                
                if ( !isset( $this->fileMetadata[$key] ) ) {
                        // try this first.  if it fails to find the row, check for lag, wait, try again. if its still missing, throw an exception.
                        // this more complex solution keeps things moving for page loads with many requests 
                        // (ie. validating image ownership) when replag is high
                        if( !$this->fetchFileMetadata($key) ) {
                                $lag = $dbr->getLag();
                                if( $lag > 0 && $lag <= self::MAX_LAG ) {
                                        // if there's not too much replication lag, just wait for the slave to catch up to our last insert.
                                        sleep( ceil( $lag ) );
                                } elseif($lag > self::MAX_LAG ) {
                                        // that's a lot of lag to introduce into the middle of the UI.
                                        throw new UploadStashMaxLagExceededException(
                                                'Couldn\'t load stashed file metadata, and replication lag is above threshold: (MAX_LAG=' . self::MAX_LAG . ')'
                                        );
                                }
                                
                                // now that the waiting has happened, try again
                                $this->fetchFileMetadata($key);
                        }
                        
                        if ( !isset( $this->fileMetadata[$key] ) ) {
                                throw new UploadStashFileNotFoundException( "key '$key' not found in stash" );
                        }

                        // create $this->files[$key]
                        $this->initFile( $key );

                        // fetch fileprops
                        $path = $this->fileMetadata[$key]['us_path'];
                        if ( $this->repo->isVirtualUrl( $path ) ) {
                                $path = $this->repo->resolveVirtualUrl( $path );
                        }
                        $this->fileProps[$key] = File::getPropsFromPath( $path );
                }
                
                if( !$noAuth ) {
                        if( $this->fileMetadata[$key]['us_user'] != $this->userId ) {
                                throw new UploadStashWrongOwnerException( "This file ($key) doesn't belong to the current user." );
                        }
                }
                
                return $this->files[$key];
        }

        /**
         * Getter for file metadata.
         *
         * @param key String: key under which file information is stored
         * @return Array
         */
        public function getMetadata ( $key ) {
                $this->getFile( $key );
                return $this->fileMetadata[$key];               
        }

        /**
         * Getter for fileProps
         *
         * @param key String: key under which file information is stored
         * @return Array
         */
        public function getFileProps ( $key ) {
                $this->getFile( $key );
                return $this->fileProps[$key];          
        }

        /**
         * Stash a file in a temp directory and record that we did this in the database, along with other metadata.
         *
         * @param $path String: path to file you want stashed
         * @param $sourceType String: the type of upload that generated this file (currently, I believe, 'file' or null)
         * @param $key String: optional, unique key for this file. Used for directory hashing when storing, otherwise not important
         * @throws UploadStashBadPathException
         * @throws UploadStashFileException
         * @throws UploadStashNotLoggedInException
         * @return UploadStashFile: file, or null on failure
         */
        public function stashFile( $path, $sourceType = null, $key = null ) {
                if ( ! file_exists( $path ) ) {
                        wfDebug( __METHOD__ . " tried to stash file at '$path', but it doesn't exist\n" );
                        throw new UploadStashBadPathException( "path doesn't exist" );
                }
                $fileProps = File::getPropsFromPath( $path );

                wfDebug( __METHOD__ . " stashing file at '$path'\n" );

                // 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.
                $extension = self::getExtensionForPath( $path );
                if ( ! preg_match( "/\\.\\Q$extension\\E$/", $path ) ) {
                        $pathWithGoodExtension = "$path.$extension";
                        if ( ! rename( $path, $pathWithGoodExtension ) ) {
                                throw new UploadStashFileException( "couldn't rename $path to have a better extension at $pathWithGoodExtension" );
                        }
                        $path = $pathWithGoodExtension;
                }

                // 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'] . "." . $extension;
                }

                $this->fileProps[$key] = $fileProps;
                
                if ( ! preg_match( self::KEY_FORMAT_REGEX, $key ) ) {
                        throw new UploadStashBadPathException( "key '$key' is not in a proper format" );
                }
                
                wfDebug( __METHOD__ . " key for '$path': $key\n" );

                // if not already in a temporary area, put it there
                $storeResult = $this->repo->storeTemp( basename( $path ), $path );

                if( ! $storeResult->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 $storeResult and we're throwing it away, but to fix it means
                        // redesigning API errors significantly.
                        // $storeResult->value just contains the virtual URL (if anything) which is probably useless to the caller
                        $error = $storeResult->getErrorsArray();
                        $error = reset( $error );
                        if ( ! count( $error ) ) {
                                $error = $storeResult->getWarningsArray();
                                $error = reset( $error );
                                if ( ! count( $error ) ) {
                                        $error = array( 'unknown', 'no error recorded' );
                                }
                        }
                        throw new UploadStashFileException( "error storing file in '$path': " . implode( '; ', $error ) );
                }
                $stashPath = $storeResult->value;
                
                // fetch the current user ID
                if( !$this->isLoggedIn ) {
                        wfDebugCallstack();
                        throw new UploadStashNotLoggedInException( __METHOD__ . ' No user is logged in, files must belong to users' );
                }

                // insert the file metadata into the db.
                wfDebug( __METHOD__ . " inserting $stashPath under $key\n" );
                $dbw = $this->repo->getMasterDb();

                // select happens on the master so this can all be in a transaction, which
                // avoids a race condition that's likely with multiple people uploading from the same
                // set of files
                $dbw->begin();
                // first, check to see if it's already there.
                $row = $dbw->selectRow(
                        'uploadstash',
                        'us_user, us_timestamp',
                        array('us_key' => $key),
                        __METHOD__
                );
                
                // The current user can't have this key if:
                // - the key is owned by someone else and
                // - the age of the key is less than REPO_AGE
                if( is_object( $row ) ) {
                        if( $row->us_user != $this->userId &&
                                $row->wfTimestamp( TS_UNIX, $row->us_timestamp ) > time() - UploadStash::REPO_AGE * 3600
                        ) {
                                $dbw->rollback();
                                throw new UploadStashWrongOwnerException( "Attempting to upload a duplicate of a file that someone else has stashed" );
                        }
                }
                
                $this->fileMetadata[$key] = array(
                        'us_user' => $this->userId,
                        'us_key' => $key,
                        'us_orig_path' => $path,
                        'us_path' => $stashPath,
                        'us_size' => $fileProps['size'],
                        'us_sha1' => $fileProps['sha1'],
                        'us_mime' => $fileProps['mime'],
                        'us_media_type' => $fileProps['media_type'],
                        'us_image_width' => $fileProps['width'],
                        'us_image_height' => $fileProps['height'],
                        'us_image_bits' => $fileProps['bits'],
                        'us_source_type' => $sourceType,
                        'us_timestamp' => $dbw->timestamp(),
                        'us_status' => 'finished'
                );
                
                // if a row exists but previous checks on it passed, let the current user take over this key.   
                $dbw->replace(
                        'uploadstash',
                        'us_key',
                        $this->fileMetadata[$key],
                        __METHOD__      
                );
                $dbw->commit();

                // store the insertid in the class variable so immediate retrieval (possibly laggy) isn't necesary.
                $this->fileMetadata[$key]['us_id'] = $dbw->insertId();

                # create the UploadStashFile object for this file.
                $this->initFile( $key );
                                
                return $this->getFile( $key );
        }

        /**
         * Remove all files from the stash.
         * Does not clean up files in the repo, just the record of them.
         *
         * @throws UploadStashNotLoggedInException
         * @return boolean: success
         */
        public function clear() {
                if( !$this->isLoggedIn ) {
                        throw new UploadStashNotLoggedInException( __METHOD__ . ' No user is logged in, files must belong to users' );
                }
                
                wfDebug( __METHOD__ . " clearing all rows for user $userId\n" );
                $dbw = $this->repo->getMasterDb();
                $dbw->delete(
                        'uploadstash',
                        array( 'us_user' => $this->userId ),
                        __METHOD__      
                );

                # destroy objects.
                $this->files = array();
                $this->fileMetadata = array();
                
                return true;
        }

        /**
         * Remove a particular file from the stash.  Also removes it from the repo.
         *
         * @throws UploadStashNotLoggedInException
         * @throws UploadStashWrongOwnerException
         * @return boolean: success
         */
        public function removeFile( $key ){
                if( !$this->isLoggedIn ) {
                        throw new UploadStashNotLoggedInException( __METHOD__ . ' No user is logged in, files must belong to users' );
                }
                
                $dbw = $this->repo->getMasterDb();
                
                // this is a cheap query. it runs on the master so that this function still works when there's lag.
                // it won't be called all that often.
                $row = $dbw->selectRow(
                        'uploadstash',
                        'us_user',
                        array('us_key' => $key),
                        __METHOD__
                );
                
                if( $row->us_user != $this->userId ) {
                        throw new UploadStashWrongOwnerException( "Can't delete: the file ($key) doesn't belong to this user." );
                }
                
                return $this->removeFileNoAuth( $key );
        }


        /**
         * Remove a file (see removeFile), but doesn't check ownership first.
         *
         * @return boolean: success
         */
        public function removeFileNoAuth( $key ) {
                wfDebug( __METHOD__ . " clearing row $key\n" );

                $dbw = $this->repo->getMasterDb();
                
                // this gets its own transaction since it's called serially by the cleanupUploadStash maintenance script
                $dbw->begin();
                $dbw->delete(
                        'uploadstash',
                        array( 'us_key' => $key),
                        __METHOD__      
                );
                $dbw->commit();
                
                // TODO: look into UnregisteredLocalFile and find out why the rv here is sometimes wrong (false when file was removed)
                // for now, ignore.
                $this->files[$key]->remove();
                
                unset( $this->files[$key] );
                unset( $this->fileMetadata[$key] );
                
                return true;
        }

        /**
         * List all files in the stash.
         *
         * @throws UploadStashNotLoggedInException
         * @return Array
         */
        public function listFiles() {
                if( !$this->isLoggedIn ) {
                        throw new UploadStashNotLoggedInException( __METHOD__ . ' No user is logged in, files must belong to users' );
                }
                
                $dbr = $this->repo->getSlaveDb();
                $res = $dbr->select(
                        'uploadstash',
                        'us_key',
                        array('us_key' => $key),
                        __METHOD__
                );

                if( !is_object( $res ) || $res->numRows() == 0 ) {
                        // nothing to do.
                        return false;
                }

                // finish the read before starting writes.
                $keys = array();
                foreach($res as $row) {
                        array_push( $keys, $row->us_key );
                }

                return $keys;
        }

        /**
         * 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.
         * XXX this is somewhat redundant with the checks that ApiUpload.php does with incoming
         * uploads versus the desired filename. Maybe we can get that passed to us...
         */
        public static function getExtensionForPath( $path ) {
                // Does this have an extension?
                $n = strrpos( $path, '.' );
                $extension = null;
                if ( $n !== false ) {
                        $extension = $n ? substr( $path, $n + 1 ) : '';
                } else {
                        // If not, assume that it should be related to the mime type of the original file.
                        $magic = MimeMagic::singleton();
                        $mimeType = $magic->guessMimeType( $path );
                        $extensions = explode( ' ', MimeMagic::singleton()->getExtensionsForType( $mimeType ) );
                        if ( count( $extensions ) ) {
                                $extension = $extensions[0];
                        }
                }

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

                return File::normalizeExtension( $extension );
        }

        /**
         * Helper function: do the actual database query to fetch file metadata.
         *
         * @param $key String: key
         * @return boolean
         */
        protected function fetchFileMetadata( $key ) {
                // populate $fileMetadata[$key]
                $dbr = $this->repo->getSlaveDb();
                $row = $dbr->selectRow(
                        'uploadstash',
                        '*',
                        array('us_key' => $key),
                        __METHOD__
                );
                
                if( !is_object( $row ) ) {
                        // key wasn't present in the database. this will happen sometimes.
                        return false;
                }
                
                $this->fileMetadata[$key] = array(
                        'us_user' => $row->us_user,
                        'us_key' => $row->us_key,
                        'us_orig_path' => $row->us_orig_path,
                        'us_path' => $row->us_path,
                        'us_size' => $row->us_size,
                        'us_sha1' => $row->us_sha1,
                        'us_mime' => $row->us_mime,
                        'us_media_type' => $row->us_media_type,
                        'us_image_width' => $row->us_image_width,
                        'us_image_height' => $row->us_image_height,
                        'us_image_bits' => $row->us_image_bits,
                        'us_source_type' => $row->us_source_type,
                        'us_timestamp' => $row->us_timestamp,
                        'us_status' => $row->us_status
                );
                
                return true;
        }
        
        /**
         * Helper function: Initialize the UploadStashFile for a given file.
         *
         * @param $path String: path to file
         * @param $key String: key under which to store the object
         * @throws UploadStashZeroLengthFileException
         * @return bool
         */
        protected function initFile( $key ) {
                $file = new UploadStashFile( $this->repo, $this->fileMetadata[$key]['us_path'], $key );
                if ( $file->getSize() === 0 ) {
                        throw new UploadStashZeroLengthFileException( "File is zero length" );
                }
                $this->files[$key] = $file;
                return true;
        }
}

class UploadStashFile extends UnregisteredLocalFile {
        private $fileKey;
        private $urlName;
        protected $url;

        /**
         * 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 $repo FSRepo: 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
         * @throws UploadStashBadPathException
         * @throws UploadStashFileNotFoundException
         */
        public function __construct( $repo, $path, $key ) {
                $this->fileKey = $key;

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

                        // 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 );

                $this->name = basename( $this->path );
        }

        /**
         * 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();
        }

        /**
         * 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.
         * We override this because we want to use the pretty url name instead of the
         * ugly file name.
         *
         * @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 ) {
                return $this->generateThumbName( $this->getUrlName(), $params );
        }

        /**
         * 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 db)
         *
         * @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 ) {
                wfDebug( __METHOD__ . " getting for $thumbName \n" );
                return $this->getSpecialUrl( 'thumb/' . $this->getUrlName() . '/' . $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->fileKey;
                }
                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 = $this->getSpecialUrl( 'file/' . $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 file key (the unique id by which this file's location & metadata is stored in the db)
         *
         * @return String: file key
         */
        public function getFileKey() {
                return $this->fileKey;
        }

        /**
         * Remove the associated temporary file
         * @return Status: success
         */
        public function remove() {
                if( !$this->repo->fileExists( $this->path, FileRepo::FILES_ONLY ) ) {
                        // Maybe the file's already been removed? This could totally happen in UploadBase.
                        return true;
                }
                
                return $this->repo->freeTemp( $this->path );
        }

}

class UploadStashNotAvailableException extends MWException {};
class UploadStashFileNotFoundException extends MWException {};
class UploadStashBadPathException extends MWException {};
class UploadStashFileException extends MWException {};
class UploadStashZeroLengthFileException extends MWException {};
class UploadStashNotLoggedInException extends MWException {};
class UploadStashWrongOwnerException extends MWException {};
class UploadStashMaxLagExceededException extends MWException {};