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 $? in
>
> > Or you can view, comment on it, or merge it online at:
> >
> > https://github.com/ClusterLabs/resource-agents/pull/45
>
> Thinking about it, I've got a problem with this whole grepping thing here.
>
> grep -z does not just "match accross newlines",
> it matches records separated by NUL in that file
> (which would be very unexpected).
>
> So it matches the full file.
>
> No anchors on the regex whatsoever.
>
> Client spec will typically have dots in them,
> both hostname and ip address form,
> which would also need to be matched literally.
>
> If you have two exports /bar and /foo/bar,
> to the same (or similar enough, see above) client spec,
> the grep for /bar will also match on /foo/bar.
>
> The mount point may also contain dots or other special chars.
>
> I don't like that, really :(
>
> Suggestion:
>
> Why not "unwrap" the exportfs output first,
> so we get one record per line,
> then match literal (grep -F)?
That sounds good to me. I wonder if the author of the patch is
subscribed here.
> That should cover most of these issues
> (appart from multiple consecutive blanks, or tabs, or newlines,
> in the mount point... would that even be "legal"?)
I don't think we'd need to support that.
> exportfs | fmt -w 1000 -t -u |
> grep -x -F "${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.
Cheers,
Dejan
> --
> : Lars Ellenberg
> : LINBIT | Your Way to High Availability
> : DRBD/HA support and consulting http://www.linbit.com
> _______________________________________________________
> Linux-HA-Dev: [email protected]
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