From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 101315 invoked by alias); 22 Oct 2015 11:50:16 -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 101305 invoked by uid 89); 22 Oct 2015 11:50:15 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 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 (AES256-GCM-SHA384 encrypted) ESMTPS; Thu, 22 Oct 2015 11:50:14 +0000 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (Postfix) with ESMTPS id 8F4F519D4D1; Thu, 22 Oct 2015 11:50:13 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t9MBoBtZ016988; Thu, 22 Oct 2015 07:50:11 -0400 Message-ID: <5628CD72.1080001@redhat.com> Date: Thu, 22 Oct 2015 13:39:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Luis Machado , gdb-patches@sourceware.org Subject: Re: [PATCH] Do not pass NULL for the string in catch_errors References: <1441809933-9612-1-git-send-email-lgustavo@codesourcery.com> <55F182B1.4020404@redhat.com> <5627739A.2090401@codesourcery.com> <5628C37E.2030208@redhat.com> <5628C715.5010701@codesourcery.com> In-Reply-To: <5628C715.5010701@codesourcery.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2015-10/txt/msg00449.txt.bz2 On 10/22/2015 12:23 PM, Luis Machado wrote: > On 10/22/2015 09:07 AM, Pedro Alves wrote: >> On 10/21/2015 12:14 PM, Luis Machado wrote: >>> On 09/10/2015 10:16 AM, Pedro Alves wrote: >>>> On 09/09/2015 03:45 PM, Luis Machado wrote: >>>>> I caught a segmentation fault while running gdb.reverse/sigall-reverse.exp, >>>>> in a mingw32 GDB, in this code path. It boils down to the code trying to >>>>> strlen () a NULL pointer. I tracked things down and it looks like >>>>> record_full_message_wrapper_safe is the only occurrence. >>>>> >>>>> We could also change catch_errors to check the char pointer and pass the >>>>> empty string automatically if the pointer is NULL. Then again, it seems like >>>>> catch_errors is going away at any time now, being potentially replaced >>>>> with catch_exceptions. >>>> >>>> It's been marked superseded for years. If you had fixed this by >>>> converting this one instance, we'd be a little closer. ;-) >>>> >>> >>> Well, we shouldn't rush! :-) >>> >>> Seriously, i've been looking into this and it doesn't look like >>> catch_exceptions/catch_exceptions_with_msg is something we'll want to >>> use in the long run either. Those couple functions also do not directly >>> replace catch_errors. >>> >>> I thought about replacing the remaining catch_errors occurrences with >>> TRY/CATCH/END_CATCH blocks, which sounds better aligned with what we >>> want to do in the future - migrating to C++ etc. Then we can finally get >>> rid of catch_errors and a few useless wrappers. How does that sound? >> >> Sounds like better leave it be then. It may be that with proper C++/RAII >> the try/catches would disappear altogether in the end, for instance. > > I see. Unfortunately, for the cases where catch_exceptions supposedly > acts similarly to catch_errors, it still doesn't work correctly because > catch_exceptions doesn't seem to cope well with error () calls, like the > case inside record-full.c. Now I'm confused -- why doesn't it? But TBC, by "leave it be", I meant "just go with your original patch". If you do want to go through and replace all catch_errors with TRY/CATCH, I don't oppose it at all. I guess I was just trying to avoid imposing extra work on you. > > With catch_exceptions, instead of catching the error and letting the > inferior continue, it will just cause the inferior to terminate. I don't understand. Why do you say this will happen? > > The other cases spread through breakpoint.c, infrun.c, solib.c etc, are > supposed to emit a message in case an error happens, as opposed to > passing an empty string. > > catch_exceptions_with_msg only allows recording a copy of the message > from an exception thrown from the guarded called function. It doesn't > emit a message passed in as argument like catch_errors. > Yeah. I'm not exactly sure why catch_errors was marked deprecated/superseded originally, but it does feel like catch_exceptions_with_msg isn't ideal either. Thanks, Pedro Alves