From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 63374 invoked by alias); 1 Jul 2017 11:56:38 -0000 Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org Received: (qmail 63343 invoked by uid 89); 1 Jul 2017 11:56:37 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy= X-Spam-User: qpsmtpd, 2 recipients X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Sat, 01 Jul 2017 11:56:36 +0000 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 338EBD5540; Sat, 1 Jul 2017 11:56:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 338EBD5540 Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=palves@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 338EBD5540 Received: from [127.0.0.1] (ovpn04.gateway.prod.ext.ams2.redhat.com [10.39.146.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id C576A627DA; Sat, 1 Jul 2017 11:56:27 +0000 (UTC) Subject: Re: [RFC PATCH 0/3] Pretty-printing for errno To: Zack Weinberg References: <20170622224456.1358-1-zackw@panix.com> <3a7946e9-d178-f878-9774-64ff44bcf5df@redhat.com> <9490d183-a57b-b336-3131-6580e4773818@redhat.com> <2f28f69b-406f-65e5-40e1-ae65632ea4f0@redhat.com> <1d38297f-f430-ca73-6d3f-a67144d08eea@redhat.com> Cc: Phil Muldoon , GNU C Library , gdb@sourceware.org, Joseph Myers , Florian Weimer , Tom Tromey , Siddhesh Poyarekar From: Pedro Alves Message-ID: Date: Sat, 01 Jul 2017 11:56:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <1d38297f-f430-ca73-6d3f-a67144d08eea@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2017-07/txt/msg00000.txt.bz2 On 06/30/2017 07:11 PM, Pedro Alves wrote: > On 06/30/2017 06:27 PM, Zack Weinberg wrote: > >>> One dirty way around it would be for the printer to >>> re-define the errno macro (using to cast __errno_location to >>> the correct type before calling it, I guess: >>> >>> (gdb) macro define errno *(*(__error_t *(*) (void)) __errno_location) () >>> >>> That's make "errno" available when you compile with levels >>> lower than -g3, too. >> >> Hmm. How would one do that from inside Python? > > There's no direct Python API, I believe. You'd just call the CLI > command directly, with gdb.execute. > > xmethods sounds like something that maybe might be useful here: > https://sourceware.org/gdb/onlinedocs/gdb/Xmethods-In-Python.html > though from the docs it sounds like you can only replace class > methods, not free functions, currently. Not sure, have never written any. BTW, it'd be very nice if the printer could replace the "#define errno *__errno_location()" with an alternative implementation that would avoid the function call, so that "print errno": #1 - would also work when debugging core dumps #2 - is just plain safer. Having gdb call functions in the inferior always carries the risk of corrupting an already corrupt inferior even more. Thanks, Pedro Alves