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From: Ludovic Brenta <ludovic@ludovic-brenta.org>
Newsgroups: comp.lang.ada
Subject: Re: The "black magic" of ioctl
Date: Thu, 21 Oct 2010 05:04:47 -0700 (PDT)
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Date: 2010-10-21T05:04:47-07:00
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Francesco Piraneo Giuliano wrote on comp.lang.ada:
>> The title of your post is quite correct; ioctl is indeed black
>> magic :)
>
>> POSIX[1] defines this function, as "obsolescent" mind you, along with
>> {a big cut - save your bandwidth!}

You cut a bit too much...

> Ok Ludovic, thank you for your great answer!
>
> So, please don't use ioctl -> black magic -> forbidden! :-)

That's not what I wrote or meant.

> But my application still need to be written and has to run under linux
> so to collect some data about linux' framebuffer I have to use ioctl;
> the only solution is to write all low level interfacing (open the
> device, get informations about, map it into memory) in C then write
> the upper level in Ada?

No; I wrote:

>> Therefore, a thick Ada binding would not expose ioctl directly
>> but instead offer a different subprogram (with the appropriate
>> parameters) for each supported value of the request parameter.
>> [...]  So I suggest you create a binding only for the specific
>> purpose you need ioctl for and use that.

What I meant by this is:

function Fixed_Info (Framebuffer : in POSIX.IO.File_Descriptor)
  return Fixed_Framebuffer_Info
is
   function ioctl
     (Framebuffer : in POSIX.IO.File_Descriptor;
      Request     : in Interfaces.C.int;
      Result      : access Fixed_Framebuffer_Info)
     return Interfaces.C.int; -- local, specific-purpose binding
   pragma Import (C, ioctl, "ioctl");
   Result : aliased Fixed_Framebuffer_Info;
begin
   if ioctl (Framebuffer, FBIOGET_FSCREENINFO, Result'Access) /= 0
then
     raise Ioctl_Error;
   end if;
   return Result;
end Fixed_Info;

> Just one question to you: Normally which OS you use with Ada?

I use Debian GNU/Linux and occasionally Debian GNU/kFreeBSD.

> Moreover, there is a more suited os to be driven with Ada programs?

Not that I know, except maybe an OS written in Ada like Lovelace or
MaRTE OS.

> Merci! ;-)

De rien :)

--
Ludovic Brenta.