From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 110420 invoked by alias); 22 Oct 2015 12:36:33 -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 110408 invoked by uid 89); 22 Oct 2015 12:36:32 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.4 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: relay1.mentorg.com Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 22 Oct 2015 12:36:31 +0000 Received: from svr-orw-fem-05.mgc.mentorg.com ([147.34.97.43]) by relay1.mentorg.com with esmtp id 1ZpF6Z-0003zB-Pi from Luis_Gustavo@mentor.com ; Thu, 22 Oct 2015 05:36:27 -0700 Received: from [172.30.15.53] (147.34.91.1) by svr-orw-fem-05.mgc.mentorg.com (147.34.97.43) with Microsoft SMTP Server id 14.3.224.2; Thu, 22 Oct 2015 05:36:27 -0700 Reply-To: Luis Machado 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> <5628CD72.1080001@redhat.com> To: Pedro Alves , From: Luis Machado Message-ID: <5628D847.4050109@codesourcery.com> Date: Thu, 22 Oct 2015 13:39:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <5628CD72.1080001@redhat.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2015-10/txt/msg00450.txt.bz2 On 10/22/2015 09:50 AM, Pedro Alves wrote: > 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. > That would be fine by me. I was just experimenting with TRY/CATCH/END_CATCH after my unsuccessful replacement of catch_errors with catch_exceptions. See below. >> >> 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? > I replaced catch_errors with catch_exceptions in record-full.c. I saw a bunch of failures in gdb.reverse/sigall-reverse.exp, starting at this point: Breakpoint 142, handle_TERM (sig=15) at ../../../gdb-head-ro/gdb/testsuite/gdb.reverse/sigall-reverse.c:378^M 378 }^M (gdb) PASS: gdb.reverse/sigall-reverse.exp: send signal TERM continue^M Continuing.^M The next instruction is syscall exit_group. It will make the program exit. Do you want to stop the program?([y] or n) yes^M Process record: inferior program stopped.^M ^M [process 21188] #1 stopped.^M The above is a normal run. If i replace catch_errors with catch_exceptions, instead of stopping the inferior, it will terminate. Maybe there is a bug somewhere, or something is being mishandled.