From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Kerrisk Subject: Re: [patch 0/3] [RFC] kernel/glibc mismatch of "readlink" syscall? Date: Tue, 04 Nov 2008 11:20:38 -0500 Message-ID: <49107656.2060101@gmail.com> References: <20081023145054.998439866@marvin.suse.de> <20081031160248.2b95d0e8@desktop.khms.westfalen.de> <200810311637.25371.dgollub@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200810311637.25371.dgollub-l3A5Bk7waGM@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: ltp-list-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Daniel Gollub Cc: ltp-list-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "A.E. Brouwer" , Kai Henningsen List-Id: linux-api@vger.kernel.org Daniel, Daniel Gollub wrote: > On Friday 31 October 2008 16:02:48 Kai Henningsen wrote: >> Am Fri, 24 Oct 2008 17:53:25 -0500 >> >> schrieb "Michael Kerrisk" : >>> Hi Daniel, >>> >>> On Thu, Oct 23, 2008 at 9:50 AM, Daniel Gollub >>> >>> wrote: >>>> EINVAL bufsiz is not positive. >>> The EINVAL error was added to man-pages-1.18 in 1997 (even though, as >>> you note, the type was "size_t"). I suspect (this was well before I >>> had any association with man-pages) that was done to reflect kernel >>> reality (since one could bypass glibc invoke the syscall directly), >>> but obviously it is inconsistent with the prototype. >> Actually, it's not inconsistent as described, though perhaps that is >> unintentional. "Not positive" isn't the same as "negative", as zero >> isn't positive either, and zero is certainly a possible value of an >> unsigned type > > True. So, at this stage I don't plan to make any change to man-pages. (Let me know if you think this is the wrong course.) > But there is still the problem for the ltp syscall test "readlink03", when > using the glibc "readlink" interface, by calling readlink with a buffer size > of "-1". > > Calling "-1" seems to be a valid code/error-path in the linux syscall > "readlink", since there is a check for less-equal zero. > > But the less zero, condition can't be reached via the glibc "readlink" > interface since this would cause fortify-check to fail (when buliding with - > D_FORITFY_SOURCE=2). > > To "workaround" the fortify check, by not compiling the testcase with - > D_FORTIFY_SOURCE=2, or trying to test the linux readlink interface by calling > directly syscall() in the testcase ... both suggestion are just workarounds - > no real solutions. > > We could also just remove the testcase of buffer size "-1". > > The problem is still, how to test the "readlink" syscall in LTP? I'd say: remove this test. And add one for bufsiz==0 if there isn't one already. -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ git://git.kernel.org/pub/scm/docs/man-pages/man-pages.git man-pages online: http://www.kernel.org/doc/man-pages/online_pages.html Found a bug? http://www.kernel.org/doc/man-pages/reporting_bugs.html ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/