From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([140.186.70.92]:43253)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <anthony@codemonkey.ws>) id 1QZRAY-0007TW-Vp
	for qemu-devel@nongnu.org; Wed, 22 Jun 2011 13:24:51 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <anthony@codemonkey.ws>) id 1QZRAX-0007D7-UB
	for qemu-devel@nongnu.org; Wed, 22 Jun 2011 13:24:50 -0400
Received: from mail-gw0-f45.google.com ([74.125.83.45]:62933)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <anthony@codemonkey.ws>) id 1QZRAX-0007CX-RG
	for qemu-devel@nongnu.org; Wed, 22 Jun 2011 13:24:49 -0400
Received: by gwb19 with SMTP id 19so520933gwb.4
	for <qemu-devel@nongnu.org>; Wed, 22 Jun 2011 10:24:48 -0700 (PDT)
Message-ID: <4E02255E.40202@codemonkey.ws>
Date: Wed, 22 Jun 2011 12:24:46 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
References: <1306927751-8352-1-git-send-email-kwolf@redhat.com>	<m3y60v5fpd.fsf@blackfin.pond.sub.org>
	<4E00C471.3060802@redhat.com>
In-Reply-To: <4E00C471.3060802@redhat.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH] qemu-char: Print strerror message on
	failure
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Kevin Wolf <kwolf@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>, qemu-devel@nongnu.org

On 06/21/2011 11:18 AM, Kevin Wolf wrote:
> Am 21.06.2011 18:09, schrieb Markus Armbruster:
>> Kevin Wolf<kwolf@redhat.com>  writes:
>>
>>> The only way for chardev drivers to communicate an error was to return a NULL
>>> pointer, which resulted in an error message that said _that_ something went
>>> wrong, but not _why_.
>>>
>>> This patch changes the interface to return 0/-errno and updates
>>> qemu_chr_open_opts to use strerror to display a more helpful error message.
>>
>> Returning the result through a pointer is awkward.  What about stuffing
>> the error code into errno?
>
> I generally like it better to return error codes explicitly instead of
> storing them in some global variable where it tends to be trampled over
> before you print the message. But if people prefer it that way, I can
> redo the patch.

I think passing a pointer to an int to receive the error is best.  That 
way a NULL can be passed to indicate that the caller doesn't care.

This matches the Error model that we're proposing else where.

Regards,

Anthony Liguori

>
> Kevin
>