file_save_upload

file_save_upload($form_field_name, $validators = array(), $destination = FALSE, $delta = NULL, $replace = FILE_EXISTS_RENAME)

function file_save_upload($form_field_name, $validators = array(), $destination = FALSE, $delta = NULL, $replace = FILE_EXISTS_RENAME) {
  $user = \Drupal::currentUser();
  static $upload_cache;

  $all_files = \Drupal::request()->files->get('files', array());
  // Make sure there's an upload to process.
  if (empty($all_files[$form_field_name])) {
    return NULL;
  }
  $file_upload = $all_files[$form_field_name];

  // Return cached objects without processing since the file will have
  // already been processed and the paths in $_FILES will be invalid.
  if (isset($upload_cache[$form_field_name])) {
    if (isset($delta)) {
      return $upload_cache[$form_field_name][$delta];
    }
    return $upload_cache[$form_field_name];
  }

  // Prepare uploaded files info. Representation is slightly different
  // for multiple uploads and we fix that here.
  $uploaded_files = $file_upload;
  if (!is_array($file_upload)) {
    $uploaded_files = array($file_upload);
  }

  $files = array();
  foreach ($uploaded_files as $i => $file_info) {
    // Check for file upload errors and return FALSE for this file if a lower
    // level system error occurred. For a complete list of errors:
    // See http://php.net/manual/features.file-upload.errors.php.
    switch ($file_info->getError()) {
      case UPLOAD_ERR_INI_SIZE:
      case UPLOAD_ERR_FORM_SIZE:
        drupal_set_message(t('The file %file could not be saved because it exceeds %maxsize, the maximum allowed size for uploads.', array('%file' => $file_info->getFilename(), '%maxsize' => format_size(file_upload_max_size()))), 'error');
        $files[$i] = FALSE;
        continue;

      case UPLOAD_ERR_PARTIAL:
      case UPLOAD_ERR_NO_FILE:
        drupal_set_message(t('The file %file could not be saved because the upload did not complete.', array('%file' => $file_info->getFilename())), 'error');
        $files[$i] = FALSE;
        continue;

      case UPLOAD_ERR_OK:
        // Final check that this is a valid upload, if it isn't, use the
        // default error handler.
        if (is_uploaded_file($file_info->getRealPath())) {
          break;
        }

        // Unknown error
      default:
        drupal_set_message(t('The file %file could not be saved. An unknown error has occurred.', array('%file' => $file_info->getFilename())), 'error');
        $files[$i] = FALSE;
        continue;

    }
    // Begin building file entity.
    $values = array(
      'uid' => $user->id(),
      'status' => 0,
      'filename' => $file_info->getClientOriginalName(),
      'uri' => $file_info->getRealPath(),
      'filesize' => $file_info->getSize(),
    );
    $values['filemime'] = \Drupal::service('file.mime_type.guesser')->guess($values['filename']);
    $file = File::create($values);

    $extensions = '';
    if (isset($validators['file_validate_extensions'])) {
      if (isset($validators['file_validate_extensions'][0])) {
        // Build the list of non-munged extensions if the caller provided them.
        $extensions = $validators['file_validate_extensions'][0];
      }
      else {
        // If 'file_validate_extensions' is set and the list is empty then the
        // caller wants to allow any extension. In this case we have to remove the
        // validator or else it will reject all extensions.
        unset($validators['file_validate_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['file_validate_extensions'] = array();
      $validators['file_validate_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).
      $file->setFilename(file_munge_filename($file->getFilename(), $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 (!\Drupal::config('system.file')->get('allow_insecure_uploads') && preg_match('/\.(php|pl|py|cgi|asp|js)(\.|$)/i', $file->getFilename()) && (substr($file->getFilename(), -4) != '.txt')) {
      $file->setMimeType('text/plain');
      // The destination filename will also later be used to create the URI.
      $file->setFilename($file->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['file_validate_extensions'][0] .= ' txt';
        drupal_set_message(t('For security reasons, your upload has been renamed to %filename.', array('%filename' => $file->getFilename())));
      }
    }

    // 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 (!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)), 'error');
      $files[$i] = FALSE;
      continue;
    }

    $file->source = $form_field_name;
    // A file URI may already have a trailing slash or look like "public://".
    if (substr($destination, -1) != '/') {
      $destination .= '/';
    }
    $file->destination = file_destination($destination . $file->getFilename(), $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) {
      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)), 'error');
      $files[$i] = FALSE;
      continue;
    }

    // Add in our check of 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 = array(
        'error' => array(
          '#markup' => t('The specified file %name could not be uploaded.', array('%name' => $file->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');
      $files[$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
    // operations.
    $file->setFileUri($file->destination);
    if (!drupal_move_uploaded_file($file_info->getRealPath(), $file->getFileUri())) {
      drupal_set_message(t('File upload error. Could not move uploaded file.'), 'error');
      \Drupal::logger('file')->notice('Upload error. Could not move uploaded file %file to destination %destination.', array('%file' => $file->getFilename(), '%destination' => $file->getFileUri()));
      $files[$i] = FALSE;
      continue;
    }

    // Set the permissions on the new file.
    drupal_chmod($file->getFileUri());

    // If we are replacing an existing file re-use its database record.
    // @todo Do not create a new entity in order to update it. See
    //   https://www.drupal.org/node/2241865.
    if ($replace == FILE_EXISTS_REPLACE) {
      $existing_files = entity_load_multiple_by_properties('file', array('uri' => $file->getFileUri()));
      if (count($existing_files)) {
        $existing = reset($existing_files);
        $file->fid = $existing->id();
        $file->setOriginalId($existing->id());
      }
    }

    // If we made it this far it's safe to record this file in the database.
    $file->save();
    $files[$i] = $file;
  }

  // Add files to the cache.
  $upload_cache[$form_field_name] = $files;

  return isset($delta) ? $files[$delta] : $files;
}