public FileSystemInterface::chmod($uri, $mode = NULL)

public FileSystemInterface::validScheme($scheme)

file_managed_file_save_upload($element, FormStateInterface $form_state) Saves any files that have been uploaded

file_get_content_headers(FileInterface $file) Examines a file entity and returns appropriate content headers

public FileSystem::basename($uri, $suffix = NULL) Gets

file_progress_implementation() Determines the preferred upload progress implementation.

public File::setOwner(UserInterface $account) Sets

An array of arrays of registered guessers keyed by priority. Type:

public ExtensionMimeTypeGuesser::guess($path)

The database connection used to store file usage information. Type: