Re: [PATCH] libxl: fix handling returns in libxl_get_version_info()

[Dario Faggioli <dario.faggioli@citrix.com>]

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On Fri, 2016-02-12 at 16:22 +0530, Harmandeep Kaur wrote:
> On Thu, Feb 11, 2016 at 3:18 PM, Dario Faggioli
> <dario.faggioli@citrix.com> wrote:
> > 
> > Another thing that you should check, and probably quickly mention
> > too,
> > is whether or not the callers of these functions --the ones inside
> > xen.git of course-- are prepared to deal with this. I mean,
> > returning
> > NULL on failure of xc_version() is, IMO, the right thing to do here
> > anyway, but it is something important to know whether more work is
> > needed to fix the callers as well, or if we're just fine.
> > 
> > To do so, search (e.g., with grep or cscope) for uses of
> > libxl_get_version_info inside the tools/ dir of xen.git. For
> > instance,
> > there is one such use in xl_cmdimpl.c, in the output_xeninfo()
> > function, which looks like it would interact well with this
> > patch...
> > Can you confirm this is the case also for all the other instances
> > and
> > note it down here?
> 
> I think NULL may not be handled properly in auto_autoballoon() in
> tools/libxl/xl.c Other instances seems okay to me.
> 
So, here:

    info = libxl_get_version_info(ctx);
    if (!info)
        return 1; /* default to on */

Why do you think this is a problem? It looks like this call site is
actually prepared to see and handle a NULL return value...

> Should I fix the caller, too?
> 
If there are issues with them, yes. If there aren't just put something
like "xxx callers are already fine xxx" in the changelog.

Regards,
Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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