/**
  * Handles private file transfers.
  *
  * Call modules that implement hook_file_download() to find out if a file is
  * accessible and what headers it should be transferred with. If one or more
  * modules returned headers the download will start with the returned headers.
  * If a module returns -1 an AccessDeniedHttpException will be thrown. If the
  * file exists but no modules responded an AccessDeniedHttpException will be
  * thrown. If the file does not exist a NotFoundHttpException will be thrown.
  *
  * @see hook_file_download()
  *
  * @param \Symfony\Component\HttpFoundation\Request $request
  *   The request object.
  * @param string $scheme
  *   The file scheme, defaults to 'private'.
  *
  * @throws \Symfony\Component\HttpKernel\Exception\NotFoundHttpException
  *   Thrown when the requested file does not exist.
  * @throws \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException
  *   Thrown when the user does not have access to the file.
  *
  * @return \Symfony\Component\HttpFoundation\BinaryFileResponse
  *   The transferred file as response.
  */
 public function download(Request $request, $scheme = 'private')
 {
     $target = $request->query->get('file');
     // Merge remaining path arguments into relative file path.
     $uri = $scheme . '://' . $target;
     if (file_stream_wrapper_valid_scheme($scheme) && file_exists($uri)) {
         // Let other modules provide headers and controls access to the file.
         $headers = $this->moduleHandler()->invokeAll('file_download', array($uri));
         foreach ($headers as $result) {
             if ($result == -1) {
                 throw new AccessDeniedHttpException();
             }
         }
         if (count($headers)) {
             return new BinaryFileResponse($uri, 200, $headers);
         }
         throw new AccessDeniedHttpException();
     }
     throw new NotFoundHttpException();
 }

 /**
  * {@inheritdoc}
  */
 public function save($destination)
 {
     $scheme = file_uri_scheme($destination);
     // Work around lack of stream wrapper support in imagejpeg() and imagepng().
     if ($scheme && file_stream_wrapper_valid_scheme($scheme)) {
         // If destination is not local, save image to temporary local file.
         $local_wrappers = file_get_stream_wrappers(STREAM_WRAPPERS_LOCAL);
         if (!isset($local_wrappers[$scheme])) {
             $permanent_destination = $destination;
             $destination = drupal_tempnam('temporary://', 'gd_');
         }
         // Convert stream wrapper URI to normal path.
         $destination = drupal_realpath($destination);
     }
     switch ($this->getType()) {
         case GDToolkitWebP::IMAGETYPE_WEBP:
             $function = 'imagewebp';
             break;
         default:
             $function = 'image' . image_type_to_extension($this->getType(), FALSE);
             break;
     }
     if (!function_exists($function)) {
         return FALSE;
     }
     if ($this->getType() == IMAGETYPE_JPEG) {
         $success = $function($this->getResource(), $destination, $this->configFactory->get('system.image.gd')->get('jpeg_quality'));
     } else {
         // Always save PNG images with full transparency.
         if ($this->getType() == IMAGETYPE_PNG) {
             imagealphablending($this->getResource(), FALSE);
             imagesavealpha($this->getResource(), TRUE);
         }
         $success = $function($this->getResource(), $destination);
     }
     // Move temporary local file to remote destination.
     if (isset($permanent_destination) && $success) {
         return (bool) file_unmanaged_move($destination, $permanent_destination, FILE_EXISTS_REPLACE);
     }
     return $success;
 }

 /**
  * Handles private file transfers.
  *
  * Call modules that implement hook_file_download() to find out if a file is
  * accessible and what headers it should be transferred with. If one or more
  * modules returned headers the download will start with the returned headers.
  * If a module returns -1 an AccessDeniedHttpException will be thrown. If the
  * file exists but no modules responded an AccessDeniedHttpException will be
  * thrown. If the file does not exist a NotFoundHttpException will be thrown.
  *
  * @see hook_file_download()
  *
  * @param \Symfony\Component\HttpFoundation\Request $request
  *   The request object.
  * @param string $scheme
  *   The file scheme, defaults to 'private'.
  *
  * @throws \Symfony\Component\HttpKernel\Exception\NotFoundHttpException
  *   Thrown when the requested file does not exist.
  * @throws \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException
  *   Thrown when the user does not have access to the file.
  *
  * @return \Symfony\Component\HttpFoundation\BinaryFileResponse
  *   The transferred file as response.
  */
 public function download(Request $request, $scheme = 'private')
 {
     $target = $request->query->get('file');
     // Merge remaining path arguments into relative file path.
     $uri = $scheme . '://' . $target;
     if (file_stream_wrapper_valid_scheme($scheme) && file_exists($uri)) {
         // Let other modules provide headers and controls access to the file.
         $headers = $this->moduleHandler()->invokeAll('file_download', array($uri));
         foreach ($headers as $result) {
             if ($result == -1) {
                 throw new AccessDeniedHttpException();
             }
         }
         if (count($headers)) {
             // \Drupal\Core\EventSubscriber\FinishResponseSubscriber::onRespond()
             // sets response as not cacheable if the Cache-Control header is not
             // already modified. We pass in FALSE for non-private schemes for the
             // $public parameter to make sure we don't change the headers.
             return new BinaryFileResponse($uri, 200, $headers, $scheme !== 'private');
         }
         throw new AccessDeniedHttpException();
     }
     throw new NotFoundHttpException();
 }

 /**
  * Test the scheme functions.
  */
 function testGetValidStreamScheme()
 {
     $this->assertEqual('foo', file_uri_scheme('foo://pork//chops'), 'Got the correct scheme from foo://asdf');
     $this->assertEqual('data', file_uri_scheme('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg=='), 'Got the correct scheme from a data URI.');
     $this->assertFalse(file_uri_scheme('foo/bar.txt'), 'foo/bar.txt is not a valid stream.');
     $this->assertTrue(file_stream_wrapper_valid_scheme(file_uri_scheme('public://asdf')), 'Got a valid stream scheme from public://asdf');
     $this->assertFalse(file_stream_wrapper_valid_scheme(file_uri_scheme('foo://asdf')), 'Did not get a valid stream scheme from foo://asdf');
 }

 /**
  * Test the scheme functions.
  */
 function testGetValidStreamScheme()
 {
     $this->assertEqual('foo', file_uri_scheme('foo://pork//chops'), 'Got the correct scheme from foo://asdf');
     $this->assertTrue(file_stream_wrapper_valid_scheme(file_uri_scheme('public://asdf')), 'Got a valid stream scheme from public://asdf');
     $this->assertFalse(file_stream_wrapper_valid_scheme(file_uri_scheme('foo://asdf')), 'Did not get a valid stream scheme from foo://asdf');
 }

//.........这里部分代码省略.........

    if (!empty($extensions)) {
      // Munge the filename to protect against possible malicious extension hiding
      // within an unknown file type (ie: filename.html.foo).
      $file->filename = file_munge_filename($file->filename, $extensions);
    }

    // Rename potentially executable files, to help prevent exploits (i.e. will
    // rename filename.php.foo and filename.php to filename.php.foo.txt and
    // filename.php.txt, respectively). Don't rename if 'allow_insecure_uploads'
    // evaluates to TRUE.
    if (!variable_get('allow_insecure_uploads', 0) && preg_match('/\.(php|pl|py|cgi|asp|js)(\.|$)/i', $file->filename) && (substr($file->filename, -4) != '.txt')) {
      $file->filemime = 'text/plain';
      $file->uri .= '.txt';
      $file->filename .= '.txt';
      // The .txt extension may not be in the allowed list of extensions. We have
      // to add it here or else the file upload will fail.
      if (!empty($extensions)) {
        $validators['file_validate_extensions'][0] .= ' txt';

        // Unlike file_save_upload() we don't need to let the user know that
        // for security reasons, your upload has been renamed, since RESTful
        // will return the file name in the response.
      }
    }

    // If the destination is not provided, use the temporary directory.
    if (empty($destination)) {
      $destination = 'temporary://';
    }

    // Assert that the destination contains a valid stream.
    $destination_scheme = file_uri_scheme($destination);
    if (!$destination_scheme || !file_stream_wrapper_valid_scheme($destination_scheme)) {
      $message = format_string('The file could not be uploaded, because the destination %destination is invalid.', array('%destination' => $destination));
      throw new \RestfulServiceUnavailable($message);
    }

    $file->source = $source;
    // A URI may already have a trailing slash or look like "public://".
    if (substr($destination, -1) != '/') {
      $destination .= '/';
    }
    $file->destination = file_destination($destination . $file->filename, $replace);
    // If file_destination() returns FALSE then $replace == FILE_EXISTS_ERROR and
    // there's an existing file so we need to bail.
    if ($file->destination === FALSE) {
      $message = format_string('The file %source could not be uploaded because a file by that name already exists in the destination %directory.', array('%source' => $source, '%directory' => $destination));
      throw new \RestfulServiceUnavailable($message);
    }

    // Add in our check of the the file name length.
    $validators['file_validate_name_length'] = array();

    // Call the validation functions specified by this function's caller.
    $errors = file_validate($file, $validators);

    // Check for errors.
    if (!empty($errors)) {
      $message = format_string('The specified file %name could not be uploaded.', array('%name' => $file->filename));
      if (count($errors) > 1) {
        $message .= theme('item_list', array('items' => $errors));
      }
      else {
        $message .= ' ' . array_pop($errors);
      }

 /**
  * Generates a derivative, given a style and image path.
  *
  * After generating an image, transfer it to the requesting agent.
  *
  * @param \Symfony\Component\HttpFoundation\Request $request
  *   The request object.
  * @param string $scheme
  *   The file scheme, defaults to 'private'.
  * @param \Drupal\image\ImageStyleInterface $image_style
  *   The image style to deliver.
  *
  * @return \Symfony\Component\HttpFoundation\BinaryFileResponse|\Symfony\Component\HttpFoundation\Response
  *   The transferred file as response or some error response.
  *
  * @throws \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException
  *   Thrown when the user does not have access to the file.
  * @throws \Symfony\Component\HttpKernel\Exception\ServiceUnavailableHttpException
  *   Thrown when the file is still being generated.
  */
 public function deliver(Request $request, $scheme, ImageStyleInterface $image_style)
 {
     $target = $request->query->get('file');
     $image_uri = $scheme . '://' . $target;
     // Check that the style is defined, the scheme is valid, and the image
     // derivative token is valid. Sites which require image derivatives to be
     // generated without a token can set the
     // 'image.settings:allow_insecure_derivatives' configuration to TRUE to
     // bypass the latter check, but this will increase the site's vulnerability
     // to denial-of-service attacks. To prevent this variable from leaving the
     // site vulnerable to the most serious attacks, a token is always required
     // when a derivative of a style is requested.
     // The $target variable for a derivative of a style has
     // styles/<style_name>/... as structure, so we check if the $target variable
     // starts with styles/.
     $valid = !empty($image_style) && file_stream_wrapper_valid_scheme($scheme);
     if (!$this->config('image.settings')->get('allow_insecure_derivatives') || strpos(ltrim($target, '\\/'), 'styles/') === 0) {
         $valid &= $request->query->get(IMAGE_DERIVATIVE_TOKEN) === $image_style->getPathToken($image_uri);
     }
     if (!$valid) {
         throw new AccessDeniedHttpException();
     }
     $derivative_uri = $image_style->buildUri($image_uri);
     $headers = array();
     // If using the private scheme, let other modules provide headers and
     // control access to the file.
     if ($scheme == 'private') {
         if (file_exists($derivative_uri)) {
             return parent::download($request, $scheme);
         } else {
             $headers = $this->moduleHandler()->invokeAll('file_download', array($image_uri));
             if (in_array(-1, $headers) || empty($headers)) {
                 throw new AccessDeniedHttpException();
             }
         }
     }
     // Don't try to generate file if source is missing.
     if (!file_exists($image_uri)) {
         // If the image style converted the extension, it has been added to the
         // original file, resulting in filenames like image.png.jpeg. So to find
         // the actual source image, we remove the extension and check if that
         // image exists.
         $path_info = pathinfo($image_uri);
         $converted_image_uri = $path_info['dirname'] . DIRECTORY_SEPARATOR . $path_info['filename'];
         if (!file_exists($converted_image_uri)) {
             $this->logger->notice('Source image at %source_image_path not found while trying to generate derivative image at %derivative_path.', array('%source_image_path' => $image_uri, '%derivative_path' => $derivative_uri));
             return new Response($this->t('Error generating image, missing source file.'), 404);
         } else {
             // The converted file does exist, use it as the source.
             $image_uri = $converted_image_uri;
         }
     }
     // Don't start generating the image if the derivative already exists or if
     // generation is in progress in another thread.
     $lock_name = 'image_style_deliver:' . $image_style->id() . ':' . Crypt::hashBase64($image_uri);
     if (!file_exists($derivative_uri)) {
         $lock_acquired = $this->lock->acquire($lock_name);
         if (!$lock_acquired) {
             // Tell client to retry again in 3 seconds. Currently no browsers are
             // known to support Retry-After.
             throw new ServiceUnavailableHttpException(3, $this->t('Image generation in progress. Try again shortly.'));
         }
     }
     // Try to generate the image, unless another thread just did it while we
     // were acquiring the lock.
     $success = file_exists($derivative_uri) || $image_style->createDerivative($image_uri, $derivative_uri);
     if (!empty($lock_acquired)) {
         $this->lock->release($lock_name);
     }
     if ($success) {
         $image = $this->imageFactory->get($derivative_uri);
         $uri = $image->getSource();
         $headers += array('Content-Type' => $image->getMimeType(), 'Content-Length' => $image->getFileSize());
         // \Drupal\Core\EventSubscriber\FinishResponseSubscriber::onRespond()
         // sets response as not cacheable if the Cache-Control header is not
         // already modified. We pass in FALSE for non-private schemes for the
         // $public parameter to make sure we don't change the headers.
         return new BinaryFileResponse($uri, 200, $headers, $scheme !== 'private');
     } else {
         $this->logger->notice('Unable to generate the derived image located at %path.', array('%path' => $derivative_uri));
//.........这里部分代码省略.........

 /**
  * Generates a derivative, given a style and image path.
  *
  * After generating an image, transfer it to the requesting agent.
  *
  * @param \Symfony\Component\HttpFoundation\Request $request
  *   The request object.
  * @param string $scheme
  *   The file scheme, defaults to 'private'.
  * @param \Drupal\image\ImageStyleInterface $image_style
  *   The image style to deliver.
  *
  * @throws \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException
  *   Thrown when the user does not have access to the file.
  * @throws \Symfony\Component\HttpKernel\Exception\ServiceUnavailableHttpException
  *   Thrown when the file is still being generated.
  *
  * @return \Symfony\Component\HttpFoundation\BinaryFileResponse|\Symfony\Component\HttpFoundation\Response
  *   The transferred file as response or some error response.
  */
 public function deliver(Request $request, $scheme, ImageStyleInterface $image_style)
 {
     $target = $request->query->get('file');
     $image_uri = $scheme . '://' . $target;
     // Check that the style is defined, the scheme is valid, and the image
     // derivative token is valid. Sites which require image derivatives to be
     // generated without a token can set the
     // 'image.settings:allow_insecure_derivatives' configuration to TRUE to
     // bypass the latter check, but this will increase the site's vulnerability
     // to denial-of-service attacks.
     $valid = !empty($image_style) && file_stream_wrapper_valid_scheme($scheme);
     if (!$this->config('image.settings')->get('allow_insecure_derivatives')) {
         $valid &= $request->query->get(IMAGE_DERIVATIVE_TOKEN) === $image_style->getPathToken($image_uri);
     }
     if (!$valid) {
         throw new AccessDeniedHttpException();
     }
     $derivative_uri = $image_style->buildUri($image_uri);
     $headers = array();
     // If using the private scheme, let other modules provide headers and
     // control access to the file.
     if ($scheme == 'private') {
         if (file_exists($derivative_uri)) {
             return parent::download($request, $scheme);
         } else {
             $headers = $this->moduleHandler()->invokeAll('file_download', array($image_uri));
             if (in_array(-1, $headers) || empty($headers)) {
                 throw new AccessDeniedHttpException();
             }
         }
     }
     // Don't try to generate file if source is missing.
     if (!file_exists($image_uri)) {
         watchdog('image', 'Source image at %source_image_path not found while trying to generate derivative image at %derivative_path.', array('%source_image_path' => $image_uri, '%derivative_path' => $derivative_uri));
         return new Response($this->t('Error generating image, missing source file.'), 404);
     }
     // Don't start generating the image if the derivative already exists or if
     // generation is in progress in another thread.
     $lock_name = 'image_style_deliver:' . $image_style->id() . ':' . Crypt::hashBase64($image_uri);
     if (!file_exists($derivative_uri)) {
         $lock_acquired = $this->lock->acquire($lock_name);
         if (!$lock_acquired) {
             // Tell client to retry again in 3 seconds. Currently no browsers are
             // known to support Retry-After.
             throw new ServiceUnavailableHttpException(3, $this->t('Image generation in progress. Try again shortly.'));
         }
     }
     // Try to generate the image, unless another thread just did it while we
     // were acquiring the lock.
     $success = file_exists($derivative_uri) || $image_style->createDerivative($image_uri, $derivative_uri);
     if (!empty($lock_acquired)) {
         $this->lock->release($lock_name);
     }
     if ($success) {
         drupal_page_is_cacheable(FALSE);
         $image = $this->imageFactory->get($derivative_uri);
         $uri = $image->getSource();
         $headers += array('Content-Type' => $image->getMimeType(), 'Content-Length' => $image->getFileSize());
         return new BinaryFileResponse($uri, 200, $headers);
     } else {
         watchdog('image', 'Unable to generate the derived image located at %path.', array('%path' => $derivative_uri));
         return new Response($this->t('Error generating image.'), 500);
     }
 }

 /**
  * Validate and set destination the destination URI.
  *
  * @param \Drupal\file\FileInterface $file
  *   The file entity object.
  * @param string $destination
  *   A string containing the URI that the file should be copied to. This must
  *   be a stream wrapper URI.
  *
  * @return bool
  *   True if the destination was sucesfully validated and set, otherwise
  *   false.
  */
 protected function prepareDestination(FileInterface $file, $destination)
 {
     // Assert that the destination contains a valid stream.
     $destination_scheme = file_uri_scheme($destination);
     if (!file_stream_wrapper_valid_scheme($destination_scheme)) {
         return FALSE;
     }
     // Prepare the destination dir.
     if (!file_exists($destination)) {
         $this->fileSystem->mkdir($destination);
     }
     // A file URI may already have a trailing slash or look like "public://".
     if (substr($destination, -1) != '/') {
         $destination .= '/';
     }
     $file->destination = file_destination($destination . $file->getFilename(), FILE_EXISTS_RENAME);
     $file->setFileUri($file->destination);
     return TRUE;
 }

//.........这里部分代码省略.........
                 // the validator or else it will reject all extensions.
                 unset($validators['embridge_asset_validate_file_extensions']);
             }
         } else {
             // No validator was provided, so add one using the default list.
             // Build a default non-munged safe list for file_munge_filename().
             $extensions = 'jpg jpeg gif png txt doc xls pdf ppt pps odt ods odp';
             $validators['embridge_asset_validate_file_extensions'] = array();
             $validators['embridge_asset_validate_file_extensions'][0] = $extensions;
         }
         if (!empty($extensions)) {
             // Munge the filename to protect against possible malicious extension
             // hiding within an unknown file type (ie: filename.html.foo).
             $asset->setFilename(file_munge_filename($asset->getFilename(), $extensions));
         }
         // Rename potentially executable files, to help prevent exploits.
         if (!\Drupal::config('system.file')->get('allow_insecure_uploads') && preg_match('/\\.(php|pl|py|cgi|asp|js)(\\.|$)/i', $asset->getFilename()) && substr($asset->getFilename(), -4) != '.txt') {
             $asset->setMimeType('text/plain');
             // The destination filename will also later be used to create the URI.
             $asset->setFilename($asset->getFilename() . '.txt');
             // The .txt extension may not be in the allowed list of extensions.
             // We have to add it here or else the file upload will fail.
             if (!empty($extensions)) {
                 $validators['embridge_asset_validate_file_extensions'][0] .= ' txt';
                 drupal_set_message(t('For security reasons, your upload has been renamed to %filename.', array('%filename' => $asset->getFilename())));
             }
         }
         // If the destination is not provided, use the temporary directory.
         if (empty($destination_dir)) {
             $destination_dir = 'temporary://';
         }
         // Assert that the destination contains a valid stream.
         $destination_scheme = file_uri_scheme($destination_dir);
         if (!file_stream_wrapper_valid_scheme($destination_scheme)) {
             drupal_set_message(t('The file could not be uploaded because the destination %destination is invalid.', array('%destination' => $destination_dir)), 'error');
             $assets[$i] = FALSE;
             continue;
         }
         // A file URI may already have a trailing slash or look like "public://".
         if (substr($destination_dir, -1) != '/') {
             $destination_dir .= '/';
         }
         $asset_destination = file_destination($destination_dir . $asset->getFilename(), $replace);
         // If file_destination() returns FALSE then $replace === FILE_EXISTS_ERROR
         // and there's an existing file so we need to bail.
         if ($asset_destination === FALSE) {
             drupal_set_message(t('The file %source could not be uploaded because a file by that name already exists in the destination %directory.', array('%source' => $form_field_name, '%directory' => $destination_dir)), 'error');
             $assets[$i] = FALSE;
             continue;
         }
         // Add in our check of the file name length.
         // TODO: Do we need this?
         // $validators['file_validate_name_length'] = array();
         // Call the validation functions specified by this function's caller.
         $errors = embridge_asset_validate($asset, $validators);
         // Check for errors.
         if (!empty($errors)) {
             $message = array('error' => array('#markup' => t('The specified file %name could not be uploaded.', array('%name' => $asset->getFilename()))), 'item_list' => array('#theme' => 'item_list', '#items' => $errors));
             // @todo Add support for render arrays in drupal_set_message()? See
             // https://www.drupal.org/node/2505497.
             drupal_set_message(\Drupal::service('renderer')->renderPlain($message), 'error');
             $assets[$i] = FALSE;
             continue;
         }
         // Move uploaded files from PHP's upload_tmp_dir to Drupal's temporary
         // directory. This overcomes open_basedir restrictions for future file