thing.ml

type winsize

let get_ws () =
  let open Ctypes in
  let open Foreign in
  let winsize : winsize structure typ = structure "winsize" in
  let ws_row = field winsize "ws_row" ushort in
  let ws_col = field winsize "ws_col" ushort in
  let ws_xpixel = field winsize "ws_xpixel" ushort in
  let ws_ypixel = field winsize "ws_ypixel" ushort in
  let () = seal winsize in
  let ioctl =
    foreign "ioctl" ~check_errno:true
      (int @-> ulong @-> ptr winsize @-> returning int)
  in
  (* No clue how to fetch this value from libc without including some silly c
     "library" that just has:
        #include <sys/ioctl.h>
        int TIOCGWINSZ() { return TIOCGWINSZ; }
      This constant is correct for my Linux system at present.
  *)
  let tiocgwinsz = 21523 in
  let ws = make winsize in
  let _ = ioctl 0 (Unsigned.ULong.of_int tiocgwinsz) @@ addr ws in
  ( Unsigned.UShort.to_int (getf ws ws_col),
    Unsigned.UShort.to_int (getf ws ws_row) )