[libvirt] [PATCH] Drop empty argument from dnsmasq call

[Eric Blake]

On 02/18/2011 07:37 AM, Guido Günther wrote:
> Hi,
> Libvirt currently fails to start with dnsmasq >= 2.56.
> since dnsmasq now bails out with empty arguments. See
> 
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=613944
> 
> for the Debian bug and
> 
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=589885
> 
> for the upstream reasoning.
> 
> Tested with 2.55 and 2.56. O.k. to apply?
> Cheers,
>  -- Guido

I was worried that this might cause a regression with older dnsmasq,
given the previous conversation on this topic:
https://www.redhat.com/archives/libvir-list/2010-December/msg00504.html

What's the oldest dnsmasq that libvirt needs to support?  I'm guessing
dnsmasq 2.45, used in RHEL 5.x, is still relevant.  A quick[1] look
through that source code:

./src/option.c:    {"pid-file", 2, 0, 'x'},

shows that --pid-file has always been an optional_argument[2], which means:

--pid-file
--pid-file=
-x

specify no pid file,

--pid-file=xyz
-xxyz

specify xyz as the pid file, and

--pid-file ''
-x ''

have always parsed the '' argument in isolation, and just been ignoring
it until this recent change.

[1] Would have been quicker if I could have found an online browseable
git repository, instead of having to download the tarball from
http://www.thekelleys.org.uk/dnsmasq/ - but thank heavens for open
source guaranteeing that I can at least find the source!
[2] Would it hurt dnsmasq to use symbolic constants from <getopt.h>
instead of magic numbers?

Therefore, ACK to this patch.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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