gnu-social/classes/File.php

<?php
// This file is part of GNU social - https://www.gnu.org/software/social
//
// GNU social is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// GNU social 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with GNU social.  If not, see <http://www.gnu.org/licenses/>.

/**
 * @category  Files
 * @package   GNUsocial
 * @author    Mikael Nordfeldth <mmn@hethane.se>
 * @author    Miguel Dantas <biodantas@gmail.com>
 * @copyright 2008-2009, 2019 Free Software Foundation http://fsf.org
 * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
 */

defined('GNUSOCIAL') || die();

/**
 * Table Definition for file
 */
class File extends Managed_DataObject
{
    public $__table = 'file';                            // table name
    public $id;                              // int(4)  primary_key not_null
    public $urlhash;                         // varchar(64)  unique_key
    public $url;                             // text
    public $filehash;                        // varchar(64)     indexed
    public $mimetype;                        // varchar(50)
    public $size;                            // int(4)
    public $title;                           // text()
    public $date;                            // int(4)
    public $protected;                       // int(4)
    public $filename;                        // text()
    public $width;                           // int(4)
    public $height;                          // int(4)
    public $modified;                        // timestamp()  not_null default_CURRENT_TIMESTAMP

    const URLHASH_ALG = 'sha256';
    const FILEHASH_ALG = 'sha256';

    public static function schemaDef()
    {
        return array(
            'fields' => array(
                'id' => array('type' => 'serial', 'not null' => true),
                'urlhash' => array('type' => 'varchar', 'length' => 64, 'description' => 'sha256 of destination URL (url field)'),
                'url' => array('type' => 'text', 'description' => 'destination URL after following possible redirections'),
                'filehash' => array('type' => 'varchar', 'length' => 64, 'not null' => false, 'description' => 'sha256 of the file contents, only for locally stored files of course'),
                'mimetype' => array('type' => 'varchar', 'length' => 50, 'description' => 'mime type of resource'),
                'size' => array('type' => 'int', 'description' => 'size of resource when available'),
                'title' => array('type' => 'text', 'description' => 'title of resource when available'),
                'date' => array('type' => 'int', 'description' => 'date of resource according to http query'),
                'protected' => array('type' => 'int', 'description' => 'true when URL is private (needs login)'),
                'filename' => array('type' => 'text', 'description' => 'if file is stored locally (too) this is the filename'),
                'width' => array('type' => 'int', 'description' => 'width in pixels, if it can be described as such and data is available'),
                'height' => array('type' => 'int', 'description' => 'height in pixels, if it can be described as such and data is available'),
                'modified' => array('type' => 'timestamp', 'not null' => true, 'description' => 'date this record was modified'),
            ),
            'primary key' => array('id'),
            'unique keys' => array(
                'file_urlhash_key' => array('urlhash'),
            ),
            'indexes' => array(
                'file_filehash_idx' => array('filehash'),
            ),
        );
    }

    public static function isProtected($url)
    {
        $protected_urls_exps = array(
            'https://www.facebook.com/login.php',
            common_path('main/login')
            );

        foreach ($protected_urls_exps as $protected_url_exp) {
            if (preg_match('!^'.preg_quote($protected_url_exp).'(.*)$!i', $url) === 1) {
                return true;
            }
        }

        return false;
    }

    /**
     * Save a new file record.
     *
     * @param array $redir_data lookup data eg from File_redirection::where()
     * @param string $given_url
     * @return File
     * @throws ServerException
     */
    public static function saveNew(array $redir_data, $given_url)
    {
        $file = null;
        try {
            // I don't know why we have to keep doing this but we run a last check to avoid
            // uniqueness bugs.
            $file = File::getByUrl($given_url);
            return $file;
        } catch (NoResultException $e) {
            // We don't have the file's URL since before, so let's continue.
        }

        // If the given url is a local attachment url, don't save a new file record.
        $uh = parse_url($given_url, PHP_URL_HOST);
        $up = parse_url($given_url, PHP_URL_PATH);
        if ($uh == common_config('site', 'server') || $uh == common_config('attachments', 'server')) {
            unset($uh);
            $r = Router::get();
            // Skip the / in the beginning or $r->map won't match
            try {
                $args = $r->map(mb_substr($up, 1));
                if ($args['action'] === 'attachment'          ||
                    $args['action'] === 'attachment_view'     ||
                    $args['action'] === 'attachment_download' ||
                    $args['action'] === 'attachment_thumbnail' ) {
                    try {
                        if (array_key_exists('attachment', $args)) {
                            return File::getByID((int)$args['attachment']);
                        } elseif (array_key_exists('filehash', $args)) {
                            $file = File::getByHash($args['filehash']);
                            $file->fetch();
                            return $file;
                        }
                    } catch (NoResultException $e) {
                        // apparently this link goes to us, but is _not_ an existing attachment (File) ID?
                    }
                }
            } catch (Exception $e) {
                // Some other exception was thrown from $r->map, likely a
                // ClientException (404) because of some malformed link to
                // our own instance. It's still a valid URL however, so we
                // won't abort anything... I noticed this when linking:
                // https://social.umeahackerspace.se/mmn/foaf' (notice the
                // apostrophe in the end, making it unrecognizable for our
                // URL routing.
                // That specific issue (the apostrophe being part of a link
                // is something that may or may not have been fixed since,
                // in lib/util.php in common_replace_urls_callback().
            }
        }

        $file = new File;
        $file->url = $given_url;
        if (!empty($redir_data['protected'])) {
            $file->protected = $redir_data['protected'];
        }
        if (!empty($redir_data['title'])) {
            $file->title = $redir_data['title'];
        }
        if (!empty($redir_data['type'])) {
            $file->mimetype = $redir_data['type'];
        }
        if (!empty($redir_data['size'])) {
            $file->size = (int)$redir_data['size'];
        }
        if (isset($redir_data['time']) && $redir_data['time'] > 0) {
            $file->date = (int)$redir_data['time'];
        }
        $file->saveFile();
        return $file;
    }

    public function saveFile()
    {
        $this->urlhash = is_null($this->url) ? null : self::hashurl($this->url);

        if (!Event::handle('StartFileSaveNew', array(&$this))) {
            throw new ServerException('File not saved due to an aborted StartFileSaveNew event.');
        }

        $this->id = $this->insert();

        if ($this->id === false) {
            throw new ServerException('File/URL metadata could not be saved to the database.');
        }

        Event::handle('EndFileSaveNew', array($this));
    }

    /**
     * Go look at a URL and possibly save data about it if it's new:
     * - follow redirect chains and store them in file_redirection
     * - if a thumbnail is available, save it in file_thumbnail
     * - save file record with basic info
     * - optionally save a file_to_post record
     * - return the File object with the full reference
     *
     * @param string $given_url the URL we're looking at
     * @param Notice|null $notice (optional)
     * @param bool $followRedirects defaults to true
     *
     * @return mixed File on success, -1 on some errors
     *
     * @throws ServerException on failure
     */
    public static function processNew($given_url, ?Notice $notice=null, bool $followRedirects=true)
    {
        if (empty($given_url)) {
            throw new ServerException('No given URL to process');
        }

        $given_url = File_redirection::_canonUrl($given_url);
        if (empty($given_url)) {
            throw new ServerException('No canonical URL from given URL to process');
        }

        $redir = File_redirection::where($given_url);
        try {
            $file = $redir->getFile();
        } catch (EmptyPkeyValueException $e) {
            common_log(LOG_ERR, 'File_redirection::where gave object with empty file_id for given_url '._ve($given_url));
            throw new ServerException('URL processing failed without new File object');
        } catch (NoResultException $e) {
            // This should not happen
            common_log(LOG_ERR, 'File_redirection after discovery could still not return a File object.');
            throw new ServerException('URL processing failed without new File object');
        }

        if ($notice instanceof Notice) {
            File_to_post::processNew($file, $notice);
        }

        return $file;
    }

    public static function respectsQuota(Profile $scoped, $fileSize)
    {
        if ($fileSize > common_config('attachments', 'file_quota')) {
            // TRANS: Message used to be inserted as %2$s in  the text "No file may
            // TRANS: be larger than %1$d byte and the file you sent was %2$s.".
            // TRANS: %1$d is the number of bytes of an uploaded file.
            $fileSizeText = sprintf(_m('%1$d byte', '%1$d bytes', $fileSize), $fileSize);

            $fileQuota = common_config('attachments', 'file_quota');
            // TRANS: Message given if an upload is larger than the configured maximum.
            // TRANS: %1$d (used for plural) is the byte limit for uploads,
            // TRANS: %2$s is the proper form of "n bytes". This is the only ways to have
            // TRANS: gettext support multiple plurals in the same message, unfortunately...
            throw new ClientException(
                sprintf(
                    _m(
                        'No file may be larger than %1$d byte and the file you sent was %2$s. Try to upload a smaller version.',
                        'No file may be larger than %1$d bytes and the file you sent was %2$s. Try to upload a smaller version.',
                        $fileQuota
                    ),
                    $fileQuota,
                    $fileSizeText
                )
            );
        }

        $file = new File;

        $query = "SELECT sum(size) AS total
                  FROM file
                       INNER JOIN file_to_post
                              ON file_to_post.file_id = file.id
                       INNER JOIN notice
                              ON file_to_post.post_id = notice.id
                  WHERE profile_id = {$scoped->id} AND
                        filename IS NULL AND
                        file.url IS NOT NULL";
        $file->query($query);
        $file->fetch();
        $total = $file->total + $fileSize;
        if ($total > common_config('attachments', 'user_quota')) {
            // TRANS: Message given if an upload would exceed user quota.
            // TRANS: %d (number) is the user quota in bytes and is used for plural.
            throw new ClientException(
                sprintf(
                    _m(
                        'A file this large would exceed your user quota of %d byte.',
                        'A file this large would exceed your user quota of %d bytes.',
                        common_config('attachments', 'user_quota')
                    ),
                    common_config('attachments', 'user_quota')
                )
            );
        }
        $query .= ' AND EXTRACT(MONTH FROM file.modified) = EXTRACT(MONTH FROM CURRENT_DATE)'
                . ' AND EXTRACT(YEAR  FROM file.modified) = EXTRACT(YEAR  FROM CURRENT_DATE)';
        $file->query($query);
        $file->fetch();
        $total = $file->total + $fileSize;
        if ($total > common_config('attachments', 'monthly_quota')) {
            // TRANS: Message given id an upload would exceed a user's monthly quota.
            // TRANS: $d (number) is the monthly user quota in bytes and is used for plural.
            throw new ClientException(
                sprintf(
                    _m(
                        'A file this large would exceed your monthly quota of %d byte.',
                        'A file this large would exceed your monthly quota of %d bytes.',
                        common_config('attachments', 'monthly_quota')
                    ),
                    common_config('attachments', 'monthly_quota')
                )
            );
        }
        return true;
    }

    public function getFilename()
    {
        return self::tryFilename($this->filename);
    }

    public function getSize(): int
    {
        return (int)$this->size;
    }

    // where should the file go?

    public static function filename(Profile $profile, $origname, $mimetype)
    {
        $ext = self::guessMimeExtension($mimetype, $origname);

        // Normalize and make the original filename more URL friendly.
        $origname = basename($origname, ".$ext");
        if (class_exists('Normalizer')) {
            // http://php.net/manual/en/class.normalizer.php
            // http://www.unicode.org/reports/tr15/
            $origname = Normalizer::normalize($origname, Normalizer::FORM_KC);
        }
        $origname = preg_replace('/[^A-Za-z0-9\.\_]/', '_', $origname);

        $nickname = $profile->getNickname();
        $datestamp = strftime('%Y%m%d', time());
        do {
            // generate new random strings until we don't run into a filename collision.
            $random = strtolower(common_confirmation_code(16));
            $filename = "$nickname-$datestamp-$origname-$random.$ext";
        } while (file_exists(self::path($filename)));
        return $filename;
    }

    /**
     * @param string $filename
     * @return null|string|bool Value from the 'extblacklist' array, in the config
     * @throws ServerException
     */
    public static function getSafeExtension(string $filename)
    {
        if (preg_match('/^.+?\.([A-Za-z0-9]+)$/', $filename, $matches) === 1) {
            // we matched on a file extension, so let's see if it means something.
            $ext = mb_strtolower($matches[1]);
            $blacklist = common_config('attachments', 'extblacklist');
            // If we got an extension from $filename we want to check if it's in a blacklist
            // so we avoid people uploading restricted files
            if (array_key_exists($ext, $blacklist)) {
                if (!is_string($blacklist[$ext])) {
                    // Blocked
                    return false;
                }
                // return a safe replacement extension ('php' => 'phps' for example)
                return $blacklist[$ext];
            } else {
                // the attachment extension based on its filename was not blacklisted so it's ok to use it
                return $ext;
            }
        } else {
            // No extension
            return null;
        }
    }

    /**
     * @param $mimetype string The mimetype we've discovered for this file.
     * @param $filename string An optional filename which we can use on failure.
     * @return mixed|string
     * @throws ClientException
     * @throws ServerException
     */
    public static function guessMimeExtension($mimetype, $filename=null)
    {
        try {
            // first see if we know the extension for our mimetype
            $ext = common_supported_mime_to_ext($mimetype);
            // we do, so use it!
            return $ext;
        } catch (UnknownMimeExtensionException $e) {
            // We don't know the extension for this mimetype, but let's guess.
            // If we can't recognize the extension from the MIME, we try
            // to guess based on filename, if one was supplied.
            if (!is_null($filename)) {
                $ext = self::getSafeExtension($filename);
                if ($ext === false) {
                    // we don't have a safe replacement extension
                    throw new ClientException(_m('Blacklisted file extension.'));
                } else {
                    return $ext;
                }
            }
        } catch (Exception $e) {
            common_log(LOG_INFO, 'Problem when figuring out extension for mimetype: '._ve($e));
        }

        // If nothing else has given us a result, try to extract it from
        // the mimetype value (this turns .jpg to .jpeg for example...)
        $matches = array();
        // Will get jpeg from image/jpeg as well as json from application/jrd+json
        if (!preg_match('/[\/+-\.]([a-z0-9]+)/', mb_strtolower($mimetype), $matches)) {
            throw new Exception("Malformed mimetype: {$mimetype}");
        }
        return mb_strtolower($matches[1]);
    }

    /**
     * Validation for as-saved base filenames
     * @param mixed $filename
     * @return false|int
     */
    public static function validFilename($filename)
    {
        return preg_match('/^[A-Za-z0-9._-]+$/', $filename);
    }

    /**
     * @param mixed $filename
     * @return string
     * @throws InvalidFilenameException
     */
    public static function tryFilename($filename): string
    {
        if (!self::validFilename($filename)) {
            throw new InvalidFilenameException($filename);
        }
        // if successful, return the filename for easy if-statementing
        return $filename;
    }

    /**
     * Construct a path
     *
     * @param mixed $filename Will be tested by tryFilename
     * @param string|null $dir Attachments directory by default
     * @param bool $test_filename
     * @return string
     * @throws InvalidFilenameException
     * @throws ServerException
     */
    public static function path($filename, ?string $dir = null, bool $test_filename = true)
    {
        if ($test_filename) {
            self::tryFilename($filename);
        }

        $dir = $dir ?? common_config('attachments', 'dir');

        if (!in_array($dir[mb_strlen($dir)-1], ['/', '\\'])) {
            $dir .= DIRECTORY_SEPARATOR;
        }

        return $dir . $filename;
    }

    /**
     * Don't use for attachments, only for assets.
     *
     * @param $filename
     * @return mixed|string
     * @throws InvalidFilenameException
     * @throws ServerException
     */
    public static function url($filename)
    {
        self::tryFilename($filename);

        if (common_config('site', 'private')) {
            return common_local_url(
                'getfile',
                array('filename' => $filename)
            );
        }

        if (GNUsocial::useHTTPS()) {
            $sslserver = common_config('attachments', 'sslserver');

            if (empty($sslserver)) {
                // XXX: this assumes that background dir == site dir + /file/
                // not true if there's another server
                if (is_string(common_config('site', 'sslserver')) &&
                    mb_strlen(common_config('site', 'sslserver')) > 0) {
                    $server = common_config('site', 'sslserver');
                } elseif (common_config('site', 'server')) {
                    $server = common_config('site', 'server');
                }
                $path = common_config('site', 'path') . '/file/';
            } else {
                $server = $sslserver;
                $path   = common_config('attachments', 'sslpath');
                if (empty($path)) {
                    $path = common_config('attachments', 'path');
                }
            }

            $protocol = 'https';
        } else {
            $path = common_config('attachments', 'path');
            $server = common_config('attachments', 'server');

            if (empty($server)) {
                $server = common_config('site', 'server');
            }

            $ssl = common_config('attachments', 'ssl');

            $protocol = ($ssl) ? 'https' : 'http';
        }

        if ($path[strlen($path)-1] != '/') {
            $path .= '/';
        }

        if ($path[0] != '/') {
            $path = '/'.$path;
        }

        return $protocol.'://'.$server.$path.$filename;
    }

    public static $_enclosures = array();

    public function getEnclosure()
    {
        if (isset(self::$_enclosures[$this->getID()])) {
            return self::$_enclosures[$this->getID()];
        }

        $enclosure = (object) array();
        foreach (array('title', 'url', 'date', 'modified', 'size', 'mimetype', 'width', 'height') as $key) {
            if ($this->$key !== '') {
                $enclosure->$key = $this->$key;
            }
        }

        $needMoreMetadataMimetypes = array(null, 'application/xhtml+xml', 'text/html');

        if (isset($enclosure->url) && in_array(common_bare_mime($enclosure->mimetype), $needMoreMetadataMimetypes)) {
            // This fetches enclosure metadata for non-local links with unset/HTML mimetypes,
            // which may be enriched through oEmbed or similar (implemented as plugins)
            Event::handle('FileEnclosureMetadata', array($this, &$enclosure));
        }
        if (empty($enclosure->mimetype)) {
            // This means we either don't know what it is, so it can't
            // be shown as an enclosure, or it is an HTML link which
            // does not link to a resource with further metadata.
            throw new ServerException('Unknown enclosure mimetype, not enough metadata');
        }

        self::$_enclosures[$this->getID()] = $enclosure;
        return $enclosure;
    }

    public function hasThumbnail()
    {
        try {
            $this->getThumbnail();
        } catch (Exception $e) {
            return false;
        }
        return true;
    }

    /**
     * Get the attachment's thumbnail record, if any or generate one.
     *
     * @param int|null $width    Max width of thumbnail in pixels. (if null, use common_config values)
     * @param int|null $height   Max height of thumbnail in pixels. (if null, square-crop to $width)
     * @param bool $crop         Crop to the max-values' aspect ratio
     * @param bool $force_still  Don't allow fallback to showing original (such as animated GIF)
     * @param bool|null $upscale Whether or not to scale smaller images up to larger thumbnail sizes. (null = site default)
     *
     * @return File_thumbnail
     *
     * @throws ClientException
     * @throws FileNotFoundException
     * @throws FileNotStoredLocallyException
     * @throws InvalidFilenameException
     * @throws NoResultException
     * @throws ServerException on various other errors
     * @throws UnsupportedMediaException if, despite trying, we can't understand how to make a thumbnail for this format
     * @throws UseFileAsThumbnailException if the file is considered an image itself and should be itself as thumbnail
     */
    public function getThumbnail (?int $width = null, ?int $height = null, bool $crop = false, bool $force_still = true, ?bool $upscale = null): File_thumbnail
    {
        return File_thumbnail::fromFileObject($this, $width, $height, $crop, $force_still, $upscale);
    }

    public function getPath()
    {
        $filepath = self::path($this->filename);
        if (!file_exists($filepath)) {
            throw new FileNotFoundException($filepath);
        }
        return $filepath;
    }

    /**
     * Returns the path to either a file, or it's thumbnail if the file doesn't exist.
     * This is useful in case the original file is deleted, or, as is the case for Embed
     * thumbnails, we only have a thumbnail and not a file
     * @param File_thumbnail|null $thumbnail
     * @return string Path
     * @throws FileNotFoundException
     * @throws FileNotStoredLocallyException
     * @throws InvalidFilenameException
     * @throws ServerException
     */
    public function getFileOrThumbnailPath(?File_thumbnail $thumbnail = null): string
    {
        if (!empty($thumbnail)) {
            return $thumbnail->getPath();
        }
        if (!empty($this->filename)) {
            $filepath = self::path($this->filename);
            if (file_exists($filepath)) {
                return $filepath;
            } else {
                throw new FileNotFoundException($filepath);
            }
        } else {
            try {
                return File_thumbnail::byFile($this, true)->getPath();
            } catch (NoResultException $e) {
                // File not stored locally
                throw new FileNotStoredLocallyException($this);
            }
        }
    }

    /**
     * Return the mime type of the thumbnail if we have it, or, if not, of the File
     * @param File_thumbnail|null $thumbnail
     * @return string
     * @throws FileNotFoundException
     * @throws NoResultException
     * @throws ServerException
     * @throws UnsupportedMediaException
     * @throws Exception
     */
    public function getFileOrThumbnailMimetype(?File_thumbnail $thumbnail = null) : string
    {
        if (!empty($thumbnail)) {
            $filepath = $thumbnail->getPath();
        } elseif (!empty($this->filename)) {
            return $this->mimetype;
        } else {
            $filepath = File_thumbnail::byFile($this, true)->getPath();
        }

        $info = @getimagesize($filepath);
        if ($info !== false) {
            return $info['mime'];
        } else {
            throw new UnsupportedMediaException(_m("Thumbnail is not an image."));
        }
    }

    /**
     * Return the size of the thumbnail if we have it, or, if not, of the File
     * @param File_thumbnail|null $thumbnail
     * @return int
     * @throws FileNotFoundException
     * @throws NoResultException
     * @throws ServerException
     */
    public function getFileOrThumbnailSize(?File_thumbnail $thumbnail = null) : int
    {
        if (!empty($thumbnail)) {
            return filesize($thumbnail->getPath());
        } elseif (!empty($this->filename)) {
            return $this->getSize();
        } else {
            return filesize(File_thumbnail::byFile($this)->getPath());
        }
    }

    public function getAttachmentUrl()
    {
        return common_local_url('attachment', array('attachment'=>$this->getID()));
    }

    public function getAttachmentDownloadUrl()
    {
        return common_local_url('attachment_download', ['filehash' => $this->filehash]);
    }

    public function getAttachmentViewUrl()
    {
        return common_local_url('attachment_view', ['filehash' => $this->filehash]);
    }

    /**
     * @param bool|null $use_local true means require local, null means prefer original, false means use whatever is stored
     * @return string
     * @throws FileNotStoredLocallyException
     */
    public function getUrl(?bool $use_local=null): ?string
    {
        if ($use_local !== false) {
            if (empty($this->url)) {
                // A locally stored file, so let's generate a URL for our instance.
                return $this->getAttachmentViewUrl();
            }
            if ($use_local) {
                // if the file isn't ours but and we require a local URL anyway
                throw new FileNotStoredLocallyException($this);
            }
        }

        // The original file's URL
        return $this->url;
    }

    public static function getByUrl($url)
    {
        $file = new File();
        $file->urlhash = self::hashurl($url);
        if (!$file->find(true)) {
            throw new NoResultException($file);
        }
        return $file;
    }

    /**
     * @param string $hashstr String of (preferrably lower case) hexadecimal characters, same as result of 'hash_file(...)'
     * @return File
     * @throws NoResultException
     */
    public static function getByHash($hashstr)
    {
        $file = new File();
        $file->filehash = strtolower($hashstr);
        if (!$file->find()) {
            throw new NoResultException($file);
        }
        return $file;
    }

    public function updateUrl($url)
    {
        $file = File::getKV('urlhash', self::hashurl($url));
        if ($file instanceof File) {
            throw new ServerException('URL already exists in DB');
        }
        $result = $this->query(sprintf(
            <<<'END'
            UPDATE %1$s
              SET urlhash = %2$s, url = %3$s, modified = CURRENT_TIMESTAMP
              WHERE urlhash = %4$s;
            END,
            $this->tableName(),
            $this->_quote((string)self::hashurl($url)),
            $this->_quote((string)$url),
            $this->_quote((string)$this->urlhash)
        ));
        if ($result === false) {
            common_log_db_error($this, 'UPDATE', __FILE__);
            throw new ServerException("Could not UPDATE {$this->tableName()}.url");
        }

        return $result;
    }

    /**
     * Blow the cache of notices that link to this URL
     *
     * @param boolean $last Whether to blow the "last" cache too
     *
     * @return void
     */

    public function blowCache($last=false)
    {
        self::blow('file:notice-ids:%s', $this->id);
        if ($last) {
            self::blow('file:notice-ids:%s;last', $this->id);
        }
        self::blow('file:notice-count:%d', $this->id);
    }

    /**
     * Stream of notices linking to this URL
     *
     * @param integer $offset   Offset to show; default is 0
     * @param integer $limit    Limit of notices to show
     * @param integer $since_id Since this notice
     * @param integer $max_id   Before this notice
     *
     * @return array ids of notices that link to this file
     */

    public function stream($offset=0, $limit=NOTICES_PER_PAGE, $since_id=0, $max_id=0)
    {
        // FIXME: Try to get the Profile::current() here in some other way to avoid mixing
        // the current session user with possibly background/queue processing.
        $stream = new FileNoticeStream($this, Profile::current());
        return $stream->getNotices($offset, $limit, $since_id, $max_id);
    }

    public function noticeCount()
    {
        $cacheKey = sprintf('file:notice-count:%d', $this->id);

        $count = self::cacheGet($cacheKey);

        if ($count === false) {
            $f2p = new File_to_post();

            $f2p->file_id = $this->id;

            $count = $f2p->count();

            self::cacheSet($cacheKey, $count);
        }

        return $count;
    }

    public function isLocal()
    {
        return empty($this->url) && !empty($this->filename);
    }

    public function unlink() {
        // Delete the file, if it exists locally
        if (!empty($this->filename) && file_exists(self::path($this->filename))) {
            $deleted = @unlink(self::path($this->filename));
            if (!$deleted) {
                common_log(LOG_ERR, sprintf('Could not unlink existing file: "%s"', self::path($this->filename)));
            }
        }
    }

    public function delete($useWhere=false)
    {
        // Delete the file, if it exists locally
        $this->unlink();

        // Clear out related things in the database and filesystem, such as thumbnails
        $related = [
            'File_redirection',
            'File_thumbnail',
            'File_to_post'
        ];
        Event::handle('FileDeleteRelated', [$this, &$related]);

        foreach ($related as $cls) {
            $inst = new $cls();
            $inst->file_id = $this->id;
            if ($inst->find()) {
                while ($inst->fetch()) {
                    $inst->delete();
                }
            }
        }

        // And finally remove the entry from the database
        return parent::delete($useWhere);
    }

    public function getTitle()
    {
        $title = $this->title ?: MediaFile::getDisplayName($this);

        return $title ?: null;
    }

    public function setTitle($title)
    {
        $orig = clone($this);
        $this->title = mb_strlen($title) > 0 ? $title : null;
        return $this->update($orig);
    }

    public static function hashurl($url)
    {
        if (empty($url)) {
            throw new Exception('No URL provided to hash algorithm.');
        }
        return hash(self::URLHASH_ALG, $url);
    }

    public static function beforeSchemaUpdate()
    {
        $table = strtolower(get_called_class());
        $schema = Schema::get();
        $schemadef = $schema->getTableDef($table);

        // 2015-02-19 We have to upgrade our table definitions to have the urlhash field populated
        if (isset($schemadef['fields']['urlhash']) && isset($schemadef['unique keys']['file_urlhash_key'])) {
            // We already have the urlhash field, so no need to migrate it.
            return;
        }
        echo "\nFound old $table table, upgrading it to contain 'urlhash' field...";

        $file = new File();
        $file->query(sprintf(
            'SELECT id, LEFT(url, 191) AS shortenedurl, COUNT(*) FROM %1$s ' .
            'WHERE LENGTH(url) > 191 GROUP BY id, shortenedurl HAVING COUNT(*) > 1',
            common_database_tablename($table)
        ));
        print "\nFound {$file->N} URLs with too long entries in file table\n";
        while ($file->fetch()) {
            // We've got a URL that is too long for our future file table
            // so we'll cut it. We could save the original URL, but there is
            // no guarantee it is complete anyway since the previous max was 255 chars.
            $dupfile = new File();
            // First we find file entries that would be duplicates of this when shortened
            // ... and we'll just throw the dupes out the window for now! It's already so borken.
            $dupfile->query(sprintf('SELECT * FROM file WHERE LEFT(url, 191) = %1$s', $dupfile->_quote($file->shortenedurl)));
            // Leave one of the URLs in the database by using ->find(true) (fetches first entry)
            if ($dupfile->find(true)) {
                print "\nShortening url entry for $table id: {$file->id} [";
                $orig = clone($dupfile);
                $origurl = $dupfile->url;   // save for logging purposes
                $dupfile->url = $file->shortenedurl;    // make sure it's only 191 chars from now on
                $dupfile->update($orig);
                print "\nDeleting duplicate entries of too long URL on $table id: {$file->id} [";
                // only start deleting with this fetch.
                while ($dupfile->fetch()) {
                    common_log(LOG_INFO, sprintf('Deleting duplicate File entry of %1$d: %2$d (original URL: %3$s collides with these first 191 characters: %4$s', $dupfile->id, $file->id, $origurl, $file->shortenedurl));
                    print ".";
                    $dupfile->delete();
                }
                print "]\n";
            } else {
                print "\nWarning! URL suddenly disappeared from database: {$file->url}\n";
            }
        }
        echo "...and now all the non-duplicates which are longer than 191 characters...\n";
        $file->query('UPDATE file SET url = LEFT(url, 191) WHERE LENGTH(url) > 191');

        echo "\n...now running hacky pre-schemaupdate change for $table:";
        // We have to create a urlhash that is _not_ the primary key,
        // transfer data and THEN run checkSchema
        $schemadef['fields']['urlhash'] = array(
                                              'type' => 'varchar',
                                              'length' => 64,
                                              'not null' => false,  // this is because when adding column, all entries will _be_ NULL!
                                              'description' => 'sha256 of destination URL (url field)',
                                            );
        $schemadef['fields']['url'] = array(
                                              'type' => 'text',
                                              'description' => 'destination URL after following possible redirections',
                                            );
        unset($schemadef['unique keys']);
        $schema->ensureTable($table, $schemadef);
        echo "DONE.\n";

        $classname = ucfirst($table);
        $tablefix = new $classname;
        // urlhash is hash('sha256', $url) in the File table
        echo "Updating urlhash fields in $table table...";
        switch (common_config('db', 'type')) {
            case 'pgsql':
                $url_sha256 = 'encode(sha256(CAST("url" AS bytea)), \'hex\')';
                break;
            case 'mysql':
                $url_sha256 = 'sha2(`url`, 256)';
                break;
            default:
                throw new ServerException('Unknown DB type selected.');
        }
        $tablefix->query(sprintf(
            'UPDATE %1$s SET urlhash = %2$s, modified = CURRENT_TIMESTAMP;',
            $tablefix->escapedTableName(),
            $url_sha256
        ));
        echo "DONE.\n";
        echo "Resuming core schema upgrade...";
    }
}