On Fri, Jan 20, 2012 at 04:18:02AM +0100, Dejan Muhamedagic wrote:
> Hi Lars,
>
> On Tue, Dec 13, 2011 at 10:55:57PM +0100, Lars Ellenberg wrote:
> > Taking this to the mailing list to give it a wider audience.
> >
> > On Tue, Dec 13, 2011 at 09:59:11AM -0800, acqant wrote:
> > > --- a/heartbeat/exportfs
> > > +++ b/heartbeat/exportfs
> > > @@ -181,9 +181,11 @@ END
> > >
> > > exportfs_monitor ()
> > > {
> > > + local clientspec_re
> > > # "grep -z" matches across newlines, which is necessary as
> > > # exportfs output wraps lines for long export directory names
> > > - exportfs | grep -zqs
> > > "${OCF_RESKEY_directory}[[:space:]]*${OCF_RESKEY_clientspec}"
> > > + clientspec_re=`echo ${OCF_RESKEY_clientspec} | sed 's/*/[*]/'`
> > > + exportfs | grep -zqs
> > > "${OCF_RESKEY_directory}[[:space:]]*${clientspec_re}"
> > >
> > > #Adapt grep status code to OCF return code
> > > case $? in
> >
> > > Or you can view, comment on it, or merge it online at:
> > >
> > > https://github.com/ClusterLabs/resource-agents/pull/45
> >
> > Thinking about it, I've got a problem with this whole grepping thing here.
> >
> > grep -z does not just "match accross newlines",
> > it matches records separated by NUL in that file
> > (which would be very unexpected).
> >
> > So it matches the full file.
> >
> > No anchors on the regex whatsoever.
> >
> > Client spec will typically have dots in them,
> > both hostname and ip address form,
> > which would also need to be matched literally.
> >
> > If you have two exports /bar and /foo/bar,
> > to the same (or similar enough, see above) client spec,
> > the grep for /bar will also match on /foo/bar.
> >
> > The mount point may also contain dots or other special chars.
> >
> > I don't like that, really :(
> >
> > Suggestion:
> >
> > Why not "unwrap" the exportfs output first,
> > so we get one record per line,
> > then match literal (grep -F)?
>
> That sounds good to me. I wonder if the author of the patch is
> subscribed here.
I first commented on his pull request on github, then basically
forwarded what I said there slightly edited to the list here.
> > That should cover most of these issues
> > (appart from multiple consecutive blanks, or tabs, or newlines,
> > in the mount point... would that even be "legal"?)
>
> I don't think we'd need to support that.
>
> > exportfs | fmt -w 1000 -t -u |
> > grep -x -F "${OCF_RESKEY_directory} ${OCF_RESKEY_clientspec}"
> >
> > I'm not completely sure about the fmt trick:
> > Availability should not be a problem (coreutils).
> > But, is the exportfs output and fmt behaviour really consistent enough
> > to have that work on all platforms?
>
> The original usage was probably just "fmt -1000" but that won't
> do. IIRC, fmt on AIX was just like that.
>
> > But since both exportfs and fmt predate linux, maybe that just works?
> >
> > If necessary, we can pull off the unwrap with sed in a more "controlled"
> > fashion as well.
>
> That'd be preferable (and you're a sed expert :) awk or perl
> would also do.
As you wish ;-)
exportfs |
sed -e '$! N; s/\n[[:space:]]\+/ /; t;
s/[[:space:]]\+\([^[:space:]]\+\)\(\n\|$\)/ \1\2/g; P;D;' |
grep -x -F "${OCF_RESKEY_directory} ${OCF_RESKEY_clientspec}"
(please someone double check that gobbledygook!)
--
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com
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