From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22306 invoked by alias); 18 Jul 2007 08:15:37 -0000 Received: (qmail 22257 invoked by uid 48); 18 Jul 2007 08:15:28 -0000 Date: Wed, 18 Jul 2007 08:15:00 -0000 Message-ID: <20070718081528.22256.qmail@sourceware.org> From: "mark at klomp dot org" To: frysk-bugzilla@sourceware.org In-Reply-To: <20070712203353.4788.pmuldoon@redhat.com> References: <20070712203353.4788.pmuldoon@redhat.com> Reply-To: sourceware-bugzilla@sourceware.org Subject: [Bug general/4788] Exe.get() Exceptions are not being thrown X-Bugzilla-Reason: AssignedTo Mailing-List: contact frysk-bugzilla-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: frysk-bugzilla-owner@sourceware.org X-SW-Source: 2007-q3/txt/msg00121.txt.bz2 List-Id: ------- Additional Comments From mark at klomp dot org 2007-07-18 08:15 ------- Hi Andrew, (In reply to comment #5) > The apparently corrupt string is caused by a kernel "feature" where it is trying > to track the executable as it is renamed. The "feature" can lead to some > strange sequences. vis, how things should work: > > $ cp /bin/bash /tmp > $ mkdir /tmp/x > $ /tmp/bash > bash$ mv /tmp/bash /tmp/x > bash$ ls -l /proc/$$/exe > -> /tmp/x/bash > > and when something is deleted: > > $ cp /bin/bash /tmp > $ /tmp/bash > bash$ rm /tmp/bash > bash$ ls -l /proc/$$/exe > -> /bin/bash (deleted) Yes, in both cases you would get a reference to a non-existing file. The code should return null if the link cannot be followed and the caller should check if they get a real file or not before proceeding. > how things get confused: > > $ cp /bin/bash /tmp > $ cp /bin/bash /tmp/a-really-long-file > $ /bin/bash > bash$ mv /tmp/a-really-long-file /tmp/bash > bash$ ls -l /proc/$$/exe > -> /bin/bash > > a dump of the contents of the link shows it in fact contains something like: > /bin/bash^@lly-long-file (deleted) > and this will occur after pre-link as been run. I couldn't easily replicate this with the above example, but this would explain why garbage was returned from the old code if really long file names/paths were used. It was using readlink in a wrong way by just allocating huge static buffers on the stack instead of calling readlink as recommended by the glibc manual: http://www.gnu.org/software/libc/manual/html_node/Symbolic-Links.html Cheers, Mark -- What |Removed |Added ---------------------------------------------------------------------------- Status|WAITING |NEW http://sourceware.org/bugzilla/show_bug.cgi?id=4788 ------- You are receiving this mail because: ------- You are the assignee for the bug, or are watching the assignee.