Date: Mon, 30 Mar 1998 14:11:29 +0300 (IDT)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Eric Gillespie <viking AT flying-brick DOT caverock DOT net DOT nz>
cc: djgpp Mailing list <djgpp AT delorie DOT com>
Subject: Re: Pipes and how to seek
In-Reply-To: <351ec431.flying-brick@flying-brick.caverock.net.nz>
Message-ID: <Pine.SUN.3.91.980330141110.19525K-100000@is>
MIME-Version: 1.0
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Precedence: bulk


On Mon, 30 Mar 1998, Eric Gillespie wrote:

> Yeah, I agree, but only in part - I do ACTUALLY want to print the garbage 
> heading through stdin, but it turns out the way I've been doing it, the 
> stdin can't be set to O_BINARY anyway 8-(, at least not in this situation:
> 
> cat strayfile.binary | hexdump
> 
> As you probably have figured out, I need the cat program to open stdin in 
> O_BINARY, not just hexdump.

Why do you need `cat's *stdin* in binary?  Isn't binary stdout enough?
If it is, then `cat' already does that automatically when its stdout
us redirected to a file or a pipe.  So I don't think you will see any
problems in the above example.

> I am also having problems when using stdin
> and then asking for a getch() directly after checking kbhit() - the 
> program locks up, though getch will work in other situations while using 
> stdin.

This is exactly one of the ``nasty side-effects'' I were talking
about.  I think that stdin should only be switched to binary when it
is NOT a console.  If you have an example of a case where you need the
console to use binary I/O in a filter-style program like `cat' and
`hexdump', please describe that case.

> I found out I could quite happily substitute getxkey for getch - it
> means it's not portable, but then I had never intended it to be (at
> least not until I port this little so and so to Linux or something...)

The portable way is to use `read' for reading the console (after
switching it to binary mode), and use `select' to check whether a key
has been hit.

Note that the above is an example of the only class of programs known
to me which *do* need to switch stdin to binary mode.  Those are the
programs which interact with the user by reading single keystrokes.
Typically, these are editors, debuggers, and other programs which
feature a user interface through the keyboard.