[libvirt] [PATCH] virsh: Strip XML declaration when extracting CPU XMLs

[Jiri Denemark]

On Thu, Nov 22, 2018 at 17:39:16 +0100, Ján Tomko wrote:
> On Thu, Nov 22, 2018 at 04:46:33PM +0100, Jiri Denemark wrote:
> >Since commit v4.3.0-336-gc84726fbdd all
> >{hypervisor-,}cpu-{baseline,compare} commands use a generic
> >vshExtractCPUDefXMLs helper for extracting individual CPU definitions
> >from the provided input file. The helper wraps the input file in a
> ><container> element so that several independent elements can be easily
> >parsed from the file. This works fine except when the file starts with
> >XML declaration (<?xml version="1.0" ... ?>) because the XML declaration
> >cannot be put inside any element. In fact it has to be at the very
> >beginning of the XML document without any preceding white space
> >characters. We can just simply skip the XML declaration.
> 
> What if someone specifies a doctype? O:)
> Also, does libvirt produce such files? I don't think we should bother
> doing extra work to undo the extra work done by the user.

Of course, we don't generate XML declarations, but I can imagine tools
formatting DOM into a file could just automatically output the XML
declaration unless you explicitly tell them not to do so. On the other
hand, nothing would output a doctype or <?xml-stylesheet ?> without an
explicit action.

Moreover, libvirt itself doesn't mind XML declarations and virsh before
4.4.0 didn't mind either.

I agree, it's probably a corner case and I was thinking about not fixing
it, but it turned out to be really easy thanks to the strict XML
specification.

> >https://bugzilla.redhat.com/show_bug.cgi?id=1595993
> 
> I only see a relation between the bug summary and this patch.
> There's no mention of the XML declaration there and no mention of the
> other issues mentioned there here in the patch.

Oops, the patch is supposed to fix another bug
https://bugzilla.redhat.com/show_bug.cgi?id=1592737

Jirka