From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22121 invoked by alias); 16 Feb 2018 12:25:37 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 20251 invoked by uid 89); 16 Feb 2018 12:25:36 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.9 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 spammy= X-HELO: mx1.redhat.com Received: from mx3-rdu2.redhat.com (HELO mx1.redhat.com) (66.187.233.73) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 16 Feb 2018 12:25:35 +0000 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BD13E40FB651; Fri, 16 Feb 2018 12:25:33 +0000 (UTC) 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 4AB481007D63; Fri, 16 Feb 2018 12:25:33 +0000 (UTC) Subject: Re: [RFA 3/3] Special case NULL when using printf's %s format To: Tom Tromey , gdb-patches@sourceware.org References: <20180215205001.337-1-tom@tromey.com> <20180215205001.337-4-tom@tromey.com> <6abda67a-ad87-ebc7-e0d4-ab60e7e4cbc6@redhat.com> From: Pedro Alves Message-ID: <5843def6-8004-4103-188c-50125c7b3d9f@redhat.com> Date: Fri, 16 Feb 2018 12:25:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <6abda67a-ad87-ebc7-e0d4-ab60e7e4cbc6@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2018-02/txt/msg00215.txt.bz2 On 02/16/2018 12:08 PM, Pedro Alves wrote: > On 02/15/2018 08:50 PM, Tom Tromey wrote: >> This changes the printf command's %s and %ls formats to special-case >> NULL, and print "(null)" for these. This is PR cli/14977. This >> behavior seems a bit friendlier; I was undecided on whether other >> invalid pointers should be handled specially somehow, so for the time >> being I've left those out. > > A question here is what to do on targets that actually map things at > address zero. IIRC, some ARM chips do that. For such ports, I think you'd > want to be able to read/print that memory. I thought we had a gdbarch hook > for that, but I'm not finding it right now. Maybe I was thinking of > has_section_at_zero in dwarf2read.c. Then again, I don't think it's likely that programs map strings at 0 (I think it's more like interrupt vectors), so for %s, it's likely that nobody would miss printing 0 as a string. So with that in mind, this is fine with me. Thanks, Pedro Alves