From owner-freebsd-hackers Thu Sep 17 09:32:48 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id JAA07100 for freebsd-hackers-outgoing; Thu, 17 Sep 1998 09:32:48 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from austin.polstra.com (austin.polstra.com [206.213.73.10]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id JAA07066 for ; Thu, 17 Sep 1998 09:32:37 -0700 (PDT) (envelope-from jdp@austin.polstra.com) Received: from austin.polstra.com (jdp@localhost) by austin.polstra.com (8.8.8/8.8.8) with ESMTP id JAA11090; Thu, 17 Sep 1998 09:32:08 -0700 (PDT) (envelope-from jdp) Message-Id: <199809171632.JAA11090@austin.polstra.com> To: bwithrow@BayNetworks.COM Subject: Re: GDB modifies shared libraries? In-Reply-To: <199809171409.KAA02717@tuva.engeast.baynetworks.com> References: <199809171409.KAA02717@tuva.engeast.baynetworks.com> Organization: Polstra & Co., Seattle, WA Cc: hackers@FreeBSD.ORG Date: Thu, 17 Sep 1998 09:32:08 -0700 From: John Polstra Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG In article <199809171409.KAA02717@tuva.engeast.baynetworks.com>, Robert Withrow wrote: > I was debugging a (large) program using GDB on an xterm (which > prevented me from getting the exact text, as you will see). This > is on 2.2.6-RELEASE on a P6-200 with 128M ram. I was running as > a normal user, not root. > > I issued the "run" command and GDB said that /usr/lib/libc.so.3.1 > had changed and it was re-loading it. That was followed immediately > by X freezing, and then a spontaneous re-boot. > > After the system re-booted, sure enough the date on /usr/lib/libc.so.3.1 > had been changed! > > Now, with this program, GDB generally says that the *program* has changed > *every* time I issue the "run" command, but I thought that was just a > GDB problem. But I don't understand how GDB can override protections > on /usr/lib/libc.so.3.1 in order to change its date. This seems like > an OS bug. Yes, it is a kernel bug. As far as I know, it doesn't actually modify the file -- it just "updates" it with its original contents, changing the timestamp. The problem is believed to be solved in -current (and hence in 3.0). At least, I haven't heard it reported there for a good long time. However, I don't think anybody (except possibly John Dyson) knows exactly what "the" fix was. -- John Polstra jdp@polstra.com John D. Polstra & Co., Inc. Seattle, Washington USA "Self-knowledge is always bad news." -- John Barth To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message