.. master:: string valid_read(string path, string uid, string func, object ob)

  This function is called to check if the object :arg:`ob` with the user-id :arg:`uid` has read permissions for the file given by :arg:`path` for the operation named by :arg:`func`. It should return 0 if permission is denied, or the normalized path if permission is granted. You can also return 1 to indicate that the :arg:`path` can be used unchanged.

  The returned pathname must not contain "..", a leading / will be stripped by the interpreter. By default, the returned path must also not contain space characters; if the driver is instructed to allow them, the preprocessor :macro:`__FILENAME_SPACES__` is defined.

  :arg:`func` denotes the efun call or other operation that caused :master:`valid_read` to be called:

  - copy_file
  - ed_start (check if the file to be edited is readable)
  - file_size
  - get_dir
  - print_file
  - read_bytes
  - read_file
  - restore_object
  - tail

  .. todo:: is print_file still right, given the removal of efun::cat?

  For :efun:`restore_object`, the :arg:`path` passed is the filename as given in the efun call.

  .. tip:: This function is called in compat mode as well. If you need to be compatible with the old 2.4.5-mudlib, redirect these calls to the :master:`valid_read` or :master:`valid_write` in the user object.

  .. seealso:: :master:`valid_write`, :master:`make_path_absolute`