From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gdb-patches-return-63268-listarch-gdb-patches=sources.redhat.com@sourceware.org>
Received: (qmail 13919 invoked by alias); 23 Apr 2009 19:35:03 -0000
Received: (qmail 13888 invoked by uid 22791); 23 Apr 2009 19:35:02 -0000
X-SWARE-Spam-Status: No, hits=-2.5 required=5.0 	tests=AWL,BAYES_00
X-Spam-Check-By: sourceware.org
Received: from sibelius.xs4all.nl (HELO sibelius.xs4all.nl) (82.92.89.47)     by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 23 Apr 2009 19:34:55 +0000
Received: from brahms.sibelius.xs4all.nl (kettenis@localhost [127.0.0.1]) 	by brahms.sibelius.xs4all.nl (8.14.3/8.14.3) with ESMTP id n3NJY7A4001570; 	Thu, 23 Apr 2009 21:34:08 +0200 (CEST)
Received: (from kettenis@localhost) 	by brahms.sibelius.xs4all.nl (8.14.3/8.14.3/Submit) id n3NJY7j7006691; 	Thu, 23 Apr 2009 21:34:07 +0200 (CEST)
Date: Thu, 23 Apr 2009 19:35:00 -0000
Message-Id: <200904231934.n3NJY7j7006691@brahms.sibelius.xs4all.nl>
From: Mark Kettenis <mark.kettenis@xs4all.nl>
To: brobecker@adacore.com
CC: gdb-patches@sourceware.org
In-reply-to: <20090423191446.GB7512@adacore.com> (message from Joel Brobecker 	on Thu, 23 Apr 2009 12:14:46 -0700)
Subject: Re: [RFA/commit] Handle EOF on terminals opened with ENONBLOCK...
References:  <20090423191446.GB7512@adacore.com>
Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm
Precedence: bulk
List-Id: <gdb-patches.sourceware.org>
List-Subscribe: <mailto:gdb-patches-subscribe@sourceware.org>
List-Archive: <http://sourceware.org/ml/gdb-patches/>
List-Post: <mailto:gdb-patches@sourceware.org>
List-Help: <mailto:gdb-patches-help@sourceware.org>, <http://sourceware.org/ml/#faqs>
Sender: gdb-patches-owner@sourceware.org
X-SW-Source: 2009-04/txt/msg00662.txt.bz2

> Date: Thu, 23 Apr 2009 12:14:46 -0700
> From: Joel Brobecker <brobecker@adacore.com>
> 
> What happens is that, by the time GDB makes a read on the pseudo-
> terminal, there is nothing to read yet, and thus gets EOF back.
> The thing to do, to detect our case, is to check the errno value,
> and try again a little later if it's EAGAIN.
> 
> 2009-04-23  Joel Brobecker   <brobecker@adacore.com>
> 
>         * utils.c: Add include of gdb_usleep.h.
>         (defaulted_query): Detect false EOF conditions that happen
>         on terminals opened with the O_NONBLOCK flag when there is
>         nothing to read.
> 
> We've tested this patch on all the hosts that AdaCore supports.
> This includes GNU/Linux, Solaris, AIX, Tru64, MinGW...
> Would it be OK to commit?

Ugh, yuck, this is gross!

I suppose the errno == EAGAIN is supposed to check whether fgetc()
failed.  However, your code has an ferror() in between, which could
clobber errno.  So perhaps it is better to reverse those checks.