Date: Mon, 19 Mar 2007 13:51:00 -0400
From: Christopher Faylor <cgf-use-the-mailinglist-please AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: rxvt isatty
Message-ID: <20070319175100.GB2452@trixie.casa.cgf.cx>
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On Mon, Mar 19, 2007 at 05:37:18PM +0100, PCJohn wrote:
>I was trying to port ivTools 
>(http://merlin.fit.vutbr.cz/wiki/index.php?title=Open_Inventor_Tools) to 
> work smoothly with Cygwin. It works on Cygwin console without problems 
>($CYGWIN=notty), but rxvt causes all the utilities to freeze.
>
>I found the problem: utilities are testing stdin by isatty. If 
>isatty==false, stdin is used for reading the data. If isatty returns 
>true, there is really bad idea to wait that user will feed the program 
>by complex 3D geometry, and utility is started without reading stdin.
>
>If rxvt is used, isatty returns always false and application does not 
>work as expected. I realized that some advanced console functionality is 
>provided with rxvt (pty, pipes) to overcome the limitations of windows 
>console. My question: Can I find out in if the application is running 
>interactive or not? If it was started like:
>app_name.exe < in.txt
>echo data | app_name.exe
>or
>app_name.exe
>
>Another minor question: How to use the advanced functionalities provided 
>by pty and pipes? Just get_osfhandle(fileno(stdin)), ReadFile, and 
>WriteFile?

Given that you're talking about things like isatty returning false,
get_osfhandle, ReadFile, and WriteFile, I surmise that you're trying to
run a non-Cygwin-based program under rxvt.  None of those are Linux/UNIX
functions and, if you use them in a Cygwin program there are no guarantees
that you will be able to use any of Cygwin's UNIX/Linux-like features.

Cygwin's ptys are entirely an invention of Cygwin so, to avail yourself
of ptys you can't build the application with MSVC or gcc -mno-cygwin or
MinGW gcc.  You really need to build your program so that it uses the
cygwin dll, i.e., it has to be compiled with the normal Cygwin gcc.

cgf

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