From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 82292 invoked by alias); 16 Feb 2018 12:08:32 -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 81967 invoked by uid 89); 16 Feb 2018 12:08:31 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.0 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RCVD_IN_DNSWL_LOW,T_RP_MATCHES_RCVD autolearn=no 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 12:08:30 +0000 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1EB87406F970; Fri, 16 Feb 2018 12:08:29 +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 89E682026E04; Fri, 16 Feb 2018 12:08:28 +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> From: Pedro Alves Message-ID: <6abda67a-ad87-ebc7-e0d4-ab60e7e4cbc6@redhat.com> Date: Fri, 16 Feb 2018 12:08:00 -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: <20180215205001.337-4-tom@tromey.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2018-02/txt/msg00214.txt.bz2 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. Thanks, Pedro Alves