void silc_sftp_read(SilcSFTP sftp,
                        SilcSFTPHandle handle,
                        SilcUInt64 offset,
                        SilcUInt32 len,
                        SilcSFTPDataCallback callback,
                        void *context);

    Reads data from the file indicated by the file handle `handle' starting
    from the offset of `offset' at most `len' bytes.  The `callback' is
    called to return the read data.