Re: Preferred way to do binray I/O on standard input/output stream

["John B. Matthews" <nospam@nospam.invalid>]

In article 
<0d02cd9f-2cf1-48b6-a10f-6ea84427139d@k4g2000yqb.googlegroups.com>,
 Hibou57 (Yannick Duchêne) <yannick_duchene@yahoo.fr> wrote:

> On 24 oct, 23:57, "Jeffrey R. Carter" <spam.jrcarter....@spam.acm.org>
> wrote:
> > Package Ada.Text_IO.Text_Streams (ARM A.12.2) allows converting
> > Ada.Text_IO.File_Type to Stream_Access and reading and writing them through 
> > the
> > capabilities of streams.
> While this seems to work most of times, I meet a malfunction (data 
> not preserved) if the stream ends with a line-feed (a byte whose 
> value is 10). When it is, this last byte seems to be dropped from the 
> stream, which cause troubles if the binary format is expecting it. 
> This occurs only when it exactly ends with this byte, and it is Ok if 
> this byte is followed by a byte whose value is 0 (as an example). It 
> does not occur when the stream ends with a byte whose value is that 
> of the carriage- return (13).
> 
> Finally, this does not really turn the stream into a binary stream, 
> and some interpretations remain.

I get the same effect. I don't know if it's the shell (bash) or OS (Mac) 
doing it. I suspect the former: End_Of_File turns True when a final 
linefeed remains to be read; the effect is absent with redirection. I'm 
vaguely uneasy using an exception for flow control, but this seems to 
copy the data unmolested:

with Ada.Text_IO; use Ada.Text_IO;
with Ada.Text_IO.Text_Streams;

procedure Copy is
   Stream_Ptr : Text_Streams.Stream_Access;
   C : Character;
begin
   Stream_Ptr := Text_Streams.Stream(Current_Input);
   loop
      Character'Read(Stream_Ptr, C);
      Put(C);
   end loop;
exception
   when End_Error => null;
end Copy;

-- 
John B. Matthews
trashgod at gmail dot com
<http://sites.google.com/site/drjohnbmatthews>