foldershare-8.x-1.2/foldershare.file.inc
foldershare.file.inc
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If this directory * name is not found, this method ignores the URI. * * When a URI does include this module's file directory name, the URI is * parsed to see if the subpath sequence that names a module file. This * sequence has the form "FILE_DIRECTORY/DIGITS/.../DIGITS.EXTENSION", where: * * - FILE_DIRECTORY is this module's file directory. * - DIGITS for the directory and file names form the 20-digit base-10 * zero-padded File entity ID of a file to access. * - EXTENSION is the filename extension for the file. * * URIs like this are created by ManageFileSystem::getFileUri(). * * If a properly formed subpath is not found, this method ignores the URI. * * When the subpath is present, the entire URI is changed to the form * ROUTE_DOWNLOADFILE/ENTITY_ID?prefix=PREFIX, where: * * - ROUTE_DOWNLOADFILE is the route path for the module's file download * controller. * * - ENTITY_ID is the File object entity ID parsed from the DIGITS above. * * - PREFIX is the portion of the original path preceding the subpath above. * * @see \Drupal\foldershare\Utilities\ManageFileSystem::getFileUri() * @see \Drupal\foldershare\Utilities\ManageFileSystem::getFileEntityId() * @see \Drupal\foldershare\Controller\FileDownload::download() * @see foldershare_file_download() * @see file_create_url() */function foldershare_file_url_alter(&$uri) { // // Check URI for the file directory // -------------------------------- // If the URI does not include this module's file directory name, then it // is not a URI we care about. The file directory name may occur anywhere // within the URI. $pos = mb_strpos($uri, ManageFileSystem::FILE_DIRECTORY); if ($pos === FALSE) { // Fail. The module's file directory name is not in the path. Ignore it. return; } // // Convert URI to URL // ------------------ // To be clear: // // - The URI passed to this function may use an internal scheme, such as // "public" or "private". This URI is only usable within Drupal and is // never shown to a user. // // - A URL for the same file maps the URI to an external form that shows up // on web pages and is sent by a browser back to Drupal to ask for the // file. This external URL may have a different path, and it certainly // has a different scheme. // // This method's goal is to alter the URI into a form that leads to a URL // that, when returned to Drupal later, routes to the file download // controller. We need to pass to that future download controller something // about the original URI so that it knows what file was requested. Since // it will be working with URLs, this method here needs to shift to // working with URLs too. // // We therefore need to map the URI to a URL. This is done by the stream // wrapper manager, which handles streams for public and private files. $mgr = \Drupal::service('stream_wrapper_manager'); $scheme = \Drupal::service('file_system')->uriScheme($uri); if ($scheme === FALSE) { $scheme = 'public'; } // Get the scheme's stream and map the URI to a URL. The returned URL // is complete, including http://hostname/path. // // This works for almost any scheme, including Drupal core's "public" and // "private" schemes, as well as any extension schemes that might reference // files in an external file system (e.g. Amazon). $stream = $mgr->getViaScheme($scheme); if ($stream === FALSE) { // Fail. Scheme is not recognized. The URI is malformed and there is // nothing more we can do. return; } $streamDirectory = $stream->getDirectoryPath(); $stream->setUri($uri); try { $url = $stream->getExternalUrl(); } catch (\Exception $e) { // Fail. The stream does not support conversion of URIs to external URLs. // The Drupal core TranslationsStream class is an example. Such a stream // is unlikely to ever be used with this method and contain this module's // FILE_DIRECTORY name, but if it does there's nothing more we can do. return; } // Parse the URL and get the path out of it. The path now includes any // path prefixes or changes added by the scheme's stream wrapper. // // For instance, the Drupal core "private" stream (class PrivateStream) // adds a prefix from the 'system.private_file_download' route, which // is always "/system/files". // // The Drupal core "public" stream (class PublicStream) does not add a // prefix. The URI's file path is presumed to be the path to a file directly // deliverable by the web server. $parsedUrl = parse_url($url); if ($parsedUrl === FALSE) { // Fail. The URL created by the stream is malformed and cannot be parsed. // Something is wrong with the stream wrapper. Nothing more we can do. return; } if (isset($parsedUrl['path']) === FALSE) { // Fail. The URL created by the stream does not have a path (i.e. it // is something like "http://host/"). Since it is the path that we need // to indicate a specific file, this doesn't make sense. The URL is // therefore malformed and there is nothing more we can do. return; } if (isset($parsedUrl['user']) === TRUE || isset($parsedUrl['pass']) === TRUE) { // Fail. The stream wrapper has added a user name and password to the URL. // This module has no mechanism to forward this to its file download // controller. This is a very unlikely situation, and one not supported // by Drupal core's "public" and "private" streams, but if it happens // there is nothing we can do. return; } $path = urldecode($parsedUrl['path']); // Check again that the returned path still references this module's // file directory. It certainly should. $pos = mb_strpos($path, ManageFileSystem::FILE_DIRECTORY); if ($pos === FALSE) { // Fail. The module's file directory name is not in the path. Ignore it. return; } // // Get prefix // ---------- // The prefix is the part of the URL path that precedes the module's // file directory name. There may be nothing. if ($pos === 0) { // No prefix. The path starts with FILE_DIRECTORY // // This only occurs for the "public" file system where external URLs // indicate site-relative paths to files that can be delivered directly // by the web server. $prefix = FALSE; } else { // There is a prefix. // // This occurs in two well-known cases (and there may be others): // // - The URL is for a file in the "private" file system, so the path has // a prefix of "/system/files". The web server sends such paths to // Drupal, which replaces "/system/files" with the full path to the // local private files directory, then returns that file. // // - The URL is for a derived file in the "public" or "private" file // system. This is the case for the Drupal core Image module, which // adds the "/styles/STYLENAME/SCHEME" prefix to refer to a styled // image derived from an image file referred to by the rest of the // file path. If the styled image doesn't exist yet then the Image // module's file download controller generates the image. For the // "public" file system, once the styled image is created it is // thereafter delivered directly by the web server. For the "private" // file system, this prefixed URL is always used and needs to go to // the Image module's file download controller to get the image and // return it. // // The prefix is important, then, because it indicates how the file // should be retrieved. For this module, all file downloads are routed // to a custom file download controller in order to do access controls. // The prefix, then, tells that download controller what to do after // checking for access - is the file delivered directly or is another // download controller invoked (e.g. Image's)? $prefix = mb_substr($path, 0, $pos); // Trim off possible last slash. $lastSlashPos = mb_strrpos($prefix, '/'); if ($lastSlashPos !== FALSE && $lastSlashPos === mb_strlen($prefix) - 1) { $prefix = mb_substr($prefix, 0, $lastSlashPos); } if ($scheme === 'public' && $prefix === $streamDirectory) { // Prefix is redundant. $prefix = FALSE; } elseif ($scheme !== 'public' && $prefix === 'system/files') { // Prefix is redundant. $prefix = FALSE; } else { $prefix = '/' . $prefix; } } // // Get entity ID // ------------- // The part of the path after the FILE_DIRECTORY contains a sequence of // subdirectory names, and a final file name, that form a zero-padded // 20-digit number for the File object entity ID. $filePath = mb_substr($path, $pos); $entityId = ManageFileSystem::getFileEntityId($filePath); if ($entityId === FALSE) { // Fail. The rest of the file path *did not* contain an entity ID. // This should not happen and indicates that the original URI was // malformed. There's nothing more we can do. return; } // // Return URI for file download controller // --------------------------------------- // Return a path that leads to the module's file download controller, // which handles access control. The path has the form // "ROUTE_DOWNLOADFILE/ENTITY_ID?prefix=PREFIX", where: // // - ROUTE_DOWNLOADFILE is the path for the route to the file download // controller. // // - ENTITY_ID is the File entity ID parsed out of the path above. // // - PREFIX (if present) is the portion of the URL preceding this module's // FILE_DIRECTORY. // // It is possible that URL created earlier from the URI also has query // and fragment components. // // Build query components. $query = ''; if (isset($parsedUrl['query']) === TRUE) { $query = '?' . urldecode($parsedUrl['query']); } if ($prefix !== FALSE) { // The path prefix is defined by whatever module added the prefix. // The Drupal core Image module, for instance, adds one of these // two prefixes: // - /styles/STYLENAME/SCHEME for public files. // - /system/files/styles/STYLENAME/SCHEME for private files. // // Other modules may have their own prefixes of arbitrary length // and structure. We need to pass the prefix on to the file download // controller. if (empty($query) === TRUE) { $query = '?'; } else { $query .= '&'; } $query .= Constants::ROUTE_DOWNLOADFILE_PREFIX . '=' . $prefix; } // Build fragment component, if any. $fragment = ''; if (isset($parsedUrl['fragment']) === TRUE) { $fragment = '#' . urldecode($parsedUrl['fragment']); } // Build the URL, without query and fragment. $url = Url::fromRoute( Constants::ROUTE_DOWNLOADFILE, [ 'file' => $entityId, ], [ 'absolute' => TRUE, ]); // The URL created above can be converted to something to return in two // ways: // - getInternalPath() returns the path part only. // - toUriString() returns a URI with "route:ROUTENAME" in front. // // The latter URI, however, causes general confusion in later Drupal // processing and the route never gets turned into a full URL for a page, // and therefore never causes the browser to invoke the URL. Fail. // // We therefore need to use getInternalPath(). Except the path does not // include any query or fragment parts. This is added here. $uri = $url->getInternalPath() . $query . $fragment;}/** * Implements hook_file_download(). * * This hook is supposed to be called by Drupal core or custom download * controllers when a file is requested from the "private" file system. * This is known to be true for the following cases: * * - Drupal core's FileDownloadController class in the "system" module. * - Drupal core's ImageStyleDownloadController class in the "image" module. * - This module's FileDownload class. * * Drupal core's FileDownloadController invokes this hook for any valid URI * scheme (i.e. "private", "public", others). ImageStyleDownloadController * and this module's FileDownload only invoke this hook for the "private" * file system. * * This hook is expected to respond in one of these ways: * * - Return NULL to indicate the file URI is not relevant to this function. * * - Return -1 to indicate that the file URI is relevant and that access * is denied. * * - Return an associative array of HTTP header key-value pairs for use if * the file is returned to a browser. * * If none of the installed hooks recognize a file and respond with HTTP * headers, then the Drupal core FileDownloadController responds with an * access denied. * * @see \Drupal\foldershare\Controller\FileDownload::download() * @see foldershare_file_url_alter() */function foldershare_file_download($uri) { // // Map URI to File // --------------- // Find the File object associated with the URI, if there is one. Since // this hook is called for every file to download (including CSS and JS // files when using a private file system), it is important that it // run quickly. We therefore use two steps: // // - Step 1 checks if the file URI contains this module's FILE_DIRECTORY. // If it does not, then it cannot be a file we need to handle. // // - Step 2 queries the database for the File entity with this URI. This // takes longer but yields the File entity we need to handle. $pos = mb_strpos($uri, ManageFileSystem::FILE_DIRECTORY); if ($pos === FALSE) { // Fail. The module's file directory name is not in the path. Ignore it. return NULL; } $files = \Drupal::entityTypeManager() ->getStorage('file') ->loadByProperties(['uri' => $uri]); if (count($files) === 0) { // Fail. No file found. This is common and occurs, for instance, when the // Drupal core Image module invokes this hook on a serived image // (e.g. one with an image style applied, such as for thumbnails). In // such cases, the URI is for a stored file, but not for a File entity. // // If there is no File entity, then this URI cannot be for a file under // management by this module. Do nothing. return NULL; } // Some database servers may use a case-insensitive comparison, so the // query may have found multiple matches. Find the correct one, if any. foreach ($files as $item) { if ($item->getFileUri() === $uri) { $file = $item; break; } } if (isset($file) === FALSE) { // Fail. No file found. While the database query found a match, it did so // on the wrong case. There isn't an exact match for the given URI and // therefore there is no associated File entity and this URI is not for // a file under management by this module. Do nothing. return NULL; } // // Check permission // ---------------- // Look for the FolderShare entity that wraps this File entity. This issues // a database query. $wrapperId = FolderShare::findFileWrapperId($file); if ($wrapperId === FALSE) { // Fail. There is none. While the URI is for a File entity, the File // entity is not one referenced by a FolderShare entity and it is, // therefore, not a file under management by this module. Do nothing. return NULL; } // Load the wrapper entity. This issues a database query. $wrapper = FolderShare::load($wrapperId); if ($wrapper === NULL) { // Fail. Something has become corrupted! The above query found the ID of a // FolderShare entity that wraps the file, but now when the entity is // loaded, the load fails. This can only happen if the entity has been // deleted between the previous call and this one. Access denied. return (-1); } // Check for view access to the FolderShare entity that manages this file. if ($wrapper->access('view') === FALSE) { // Fail. Access denied. return (-1); } // // Return headers // -------------- // The URI references a File entity under management by this module, // and the user has 'view' access. Return headers that include the // user-visible name for the file, it's MIME type, etc. // // Including the user-visible file name in the header is essential. // The file name in the URI is an internal numeric name (see // ManageFileSystem::getFileUri()). If the user tries to save the delivered // file, they'll get that numeric name instead of the user-visible name // if we didn't include the correct name in the HTTP header. return [ // Use the File object's MIME type. 'Content-Type' => Unicode::mimeHeaderEncode($file->getMimeType()), // Use the human-visible file name. 'Content-Disposition' => 'filename="' . $file->getFilename() . '"', // Use the saved file size, in bytes. 'Content-Length' => $file->getSize(), // Don't cache the file because permissions and content may change. 'Pragma' => 'no-cache', 'Cache-Control' => 'must-revalidate, post-check=0, pre-check=0', 'Expires' => '0', 'Accept-Ranges' => 'bytes', ];} |
