x                  The wide-character code of the character read.
    WEOF               Indicates the end-of-file or an error. If a
                       read error occurs, the function sets errno to
                       one of the following:

                       o  EALREADY - An operation is already in
                          progress on the same file.

                       o  EBADF - The file descriptor is not valid.

                       o  EILSEQ - Invalid character detected.