_IO_off_t
_IO_off_t pos_at_line_start;
typedef _IO_off_t streamoff;
typedef _IO_off_t streampos;
static _IO_pos_t _IO_sb_seekoff(_IO_FILE *fp, _IO_off_t pos, int dir, int mode)
static _IO_pos_t _IO_sb_seek(_IO_FILE *fp, _IO_off_t off, int dir)
int (*seek) (_IO_FILE *, _IO_off_t, int);
seek = (int (*)(_IO_FILE *, _IO_off_t, int)) cfile->__io_functions.seek;
_IO_off_t _old_offset; /* This used to be _offset but it's too small. */