Re: [Xen-devel] [RFC PATCH 2/6] libxl: stop using libxl__xs_mkdir() for ~/control/shutdown

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Ian Jackson [mailto:Ian.Jackson@xxxxxxxxxxxxx]
> Sent: 24 November 2015 17:39
> To: Paul Durrant
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Stefano Stabellini; Ian Campbell; Wei Liu
> Subject: RE: [RFC PATCH 2/6] libxl: stop using libxl__xs_mkdir() for
> ~/control/shutdown
> 
> Paul Durrant writes ("RE: [RFC PATCH 2/6] libxl: stop using libxl__xs_mkdir()
> for ~/control/shutdown"):
> > From: Ian Jackson [mailto:Ian.Jackson@xxxxxxxxxxxxx]
> > > And even if the node did somehow end up with a nonempty value,
> nothing
> > > would break because no-one would read it.
> >
> > Maybe. Personally I would have thought a toolstack would want to put
> things into a known state and XS_MKDIR just doesn't do that.
> 
> Hrm.
> 
> > > > If you use XS_WRITE then it is and I think that is the correct
> > > > semantic here (even though we happen to get away with it at the
> > > > moment). I'm happy with the function rename, but would you be
> happy
> > > > with the change in semantic?
> > >
> > > XS_MKDIR creates missing parents, which XS_WRITE doesn't.
> >
> > According to the documentation it does: (from xenstore.txt)
> >
> > READ                        <path>|                 <value|>
> > WRITE                       <path>|<value|>
> >     Store and read the octet string <value> at <path>.
> >     WRITE creates any missing parent paths, with empty values.
> 
> Oh!
> 
> Well so then perhaps we should jsut change libxl__xs_mkdir to use
> WRITE.

I think the rename to libxl__xs_mknode() is warranted, and will avoid anyone's 
belief that the implementer typo-ed the actual XS command :-)

>  This rather confusing situation is probably worth a doc
> comment next to the prototype in libxl_internal.h.

Yep. That sounds like a good idea. I'll do that.

  Paul

> 
> Ian.

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