SM_IO_SEEK_CUR
pos = (*fp->f_seek)(fp, (off_t) 0, SM_IO_SEEK_CUR);
case SM_IO_SEEK_CUR:
curoff = (*seekfn)(fp, (off_t) 0, SM_IO_SEEK_CUR);
curoff = (*seekfn)(fp, (off_t) 0, SM_IO_SEEK_CUR);
case SM_IO_SEEK_CUR: