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44 lines
1.3 KiB
44 lines
1.3 KiB
8 years ago
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(*
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* Copyright (c) 2016 - present Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*)
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(** bindings to ioctl(2) that only capture what we need *)
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open! IStd
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open Ctypes
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type winsize
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(* as found in asm-generic/termios.h *)
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let winsize : winsize structure typ = structure "winsize"
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let ws_row = field winsize "ws_row" ushort
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let ws_col = field winsize "ws_col" ushort
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let ws_xpixel = field winsize "ws_xpixel" ushort
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let ws_ypixel = field winsize "ws_ypixel" ushort
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let () = seal winsize
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(* as found in asm-generic/ioctls.h *)
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let request_TIOCGWINSZ = Unsigned.ULong.of_int 0x5413
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(* ioctl(2) is a variadic function, so cross our fingers that the calling convention works the same
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as non-variadic functions and define different ioctl_* functions for each need *)
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let ioctl_winsize =
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Foreign.foreign "ioctl"
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(int @-> ulong @-> ptr winsize @-> returning int)
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(** high-level function *)
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let terminal_width = lazy(
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let winsize = make winsize in
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let return = ioctl_winsize 0 request_TIOCGWINSZ (addr winsize) in
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if return >= 0 then
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Ok (Unsigned.UShort.to_int (getf winsize ws_col))
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else
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Error return
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)
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