Re: [Libguestfs] [PATCH 5/7] New APIs: add-domain and add-libvirt-dom.

On Wed, Nov 10, 2010 at 01:17:54PM +0000, Daniel P. Berrange wrote: > On Wed, Nov 10, 2010 at 11:46:31AM +0000, Richard W.M. Jones wrote: > > +# This comes from the Sys::Virt bindings. > > +INPUT > > +O_OBJECT_domain > > + if (sv_isobject ($arg) && (SvTYPE (SvRV ($arg)) == SVt_PVMG)) > > + $var = ($type)SvIV ((SV*) SvRV ($arg)); > > + else { > > + warn(\"${Package}::$func_name() -- $var is not a blessed SV reference\"); > > + XSRETURN_UNDEF; > > + } > > I haven't been considering this Sys::Virt type mapping to be > part of the stable ABI/API, just an internal impl details. I'm > wondering how other Perl XS modules allow extension, without > exposing their internal typedef implementation detail. Yup, this is a general problem with providing integration for these pointers through any non-C language bindings. It could be alleviated by having Sys::Virt provide a little bit of C to perform the SV -> pointer conversion -- I think if it was in Sys/Virt/Virt.so then we would be able to link to it. > > + /* Connect to libvirt, find the domain. */ > > + conn = virConnectOpenReadOnly (libvirturi); > > + if (!conn) { > > + err = virGetLastError (); > > + error (g, _("could not connect to libvirt (code %d, domain %d): %s"), > > + err->code, err->domain, err->message); > > + goto cleanup; > > + } > > + > > + dom = virDomainLookupByName (conn, domain_name); > > + if (!dom) { > > + err = virConnGetLastError (conn); > > NB, virConnGetLastError() is deprecated because it isn't threadsafe. > Instead use virGetLastError() in all places. Can I call this if I don't have a connection pointer? See first case above.

> > + xpfilename = xmlXPathEvalExpression (BAD_CAST "./source/@dev", xpathCtx); > > + if (xpfilename == NULL || > > + xpfilename->nodesetval == NULL || > > + xpfilename->nodesetval->nodeNr == 0) { > > + xmlXPathFreeObject (xpfilename); > > + xpathCtx->node = nodes->nodeTab[i]; > > + xpfilename = xmlXPathEvalExpression (BAD_CAST "./source/@file", xpathCtx); > > + if (xpfilename == NULL || > > + xpfilename->nodesetval == NULL || > > + xpfilename->nodesetval->nodeNr == 0) { > > + xmlXPathFreeObject (xpfilename); > > + continue; /* disk filename not found, skip this */ > > + } > > + } > > Rather than checking for @dev, and then checking for @file, it is safer > to fetch @type, and then if type=='file' use @file and if type=='block' > use @dev. This protects against addition of future types, which may > libguestfs may not be able to treat as simple paths on a local disk. OK I will change this. Was there a reason to split dev and file in the first place?