Re: [LTP] pidns31: fix EACCESS error in mq_open()

[Subrata Modak <subrata@linux.vnet.ibm.com>]

On Wed, 2010-10-27 at 22:22 -0700, Sukadev Bhattiprolu wrote: 
> Garrett Cooper [yanegomi@gmail.com] wrote:
> | On Mon, Aug 16, 2010 at 7:52 AM, Subrata Modak
> | <subrata@linux.vnet.ibm.com> wrote:
> | >
> | > On Wed, 2010-08-04 at 18:43 -0700, Sukadev Bhattiprolu wrote:
> | >> Garrett Cooper [yanegomi@gmail.com] wrote:
> | >> | On Wed, Aug 4, 2010 at 4:52 PM, Sukadev Bhattiprolu
> | >> | <sukadev@linux.vnet.ibm.com> wrote:
> | >> | >
> | >> | > pidns31: mq_open() fails with EACCESS.
> | >> | >
> | >> | > pidns31 test case fails with EACCESS - due to the leading '/' in
> | >> | > mqname. See comments in the patch below for details.
> | >> | >
> | >> | > Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
> | >> | > ---
> | >> | > Index: testcases/kernel/containers/pidns/pidns31.c
> | >> | > ===================================================================
> | >> | > RCS file: /cvsroot/ltp/ltp/testcases/kernel/containers/pidns/pidns31.c,v
> | >> | > retrieving revision 1.6
> | >> | > diff -u -p -r1.6 pidns31.c
> | >> | > --- testcases/kernel/containers/pidns/pidns31.c 14 Nov 2009 23:58:26 -0000      1.6
> | >> | > +++ testcases/kernel/containers/pidns/pidns31.c 4 Aug 2010 23:24:54 -0000
> | >> | > @@ -61,7 +61,14 @@
> | >> | >  char *TCID = "pidns31";
> | >> | >  int TST_TOTAL = 1;
> | >> | >
> | >> | > -char *mqname = "/mq1";
> | >> | > +
> | >> | > +/*
> | >> | > + * NOTE: The mq_open() interface in glibc requires mqname to start with a '/'
> | >> | > + *      and the glibc call skips the leading '/' when invoking the system
> | >> | > + *      call. Since we bypass the glibc mq_open() (and use syscall()) we
> | >> | > + *      define mqname without the leading '/'.
> | >> | > + */
> | >> | > +char *mqname = "mq1";
> | >> | >  int result = TFAIL;
> | >> | >
> | >> | >  int errno;
> | >> | > @@ -264,6 +271,7 @@ int main(int argc, char *argv[])
> | >> | >        }
> | >> | >
> | >> | >        syscall(__NR_mq_unlink, mqname);
> | >> | > +
> | >> | >        mqd = syscall(__NR_mq_open, mqname, O_RDWR|O_CREAT|O_EXCL, 0777, NULL);
> | >> | >        if (mqd == (mqd_t)-1) {
> | >> | >                tst_resm(TBROK, "parent: mq_open() failed (%s)",
> | >> |
> | >> | Did Linux become non-POSIX compliant :) (from
> | >> | <http://www.opengroup.org/onlinepubs/000095399/functions/mq_open.html>)?
> | >>
> | >> Heh. Good question but I think the mq_open() from glibc is compliant
> | >> with this. I am just not sure if the call via syscall() needs to be
> | >> compliant.
> | >>
> | >> But if that is a concern, we need a separate a test case for that -
> | >> pidns31 is using mq_* to test an unrelated feature. I think would
> | >> make sense to apply this fix, allowing LTP to test the feature even
> | >> on older distros.
> | >>
> | >> Or pidns31 can go back to using the library interface and we could
> | >> skip the test on old distros.
> | >
> | > I would prefer this.
> | 
> | Do I hear someone volunteering to add the required autoconf tests and
> | tests for this :)?
> 
> Well, I thought we could add a simple autoconf test for the pidns - but
> then realized that mq_open() calls were changed for many other test cases
> too. The test cases include mqueue.h, which would not be present in old
> distros anyway.
> 
> So, I don't see the point in fixing this just for pidns tests. If we want 
> to use the syscall() interface, why don't we just design the test to work 
> with the syscall behavior - i.e  just remove the '/' from the name ?

Garret,

Your thoughts ?

Regards--
Subrata

> 
> Sukadev


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