[libvirt] [PATCH/RFC]: don't ignore errors to save the domain status file

Hi, we currently don't report errors to save qemu's domain status file back to the caller. That was o.k. as long as the code was there for testing but now that the XML is being picked up on daemon restart we must handle these. The attached patch does that, although I'm not confident that it's enough. While we return error on device attach/unattach the device actually got attached/unattached already. Same is true for suspend/resume. A better solution would be to write out the new domain status into a temp file and simply call rename(2) on it when the attach/unattach succeeds and discard it if it fails. This would minimize the possible error conditions like disk full, missing permissions to write into that directory etc. Does this sound reasonable? O.k. to apply the attached version for now? Cheers, -- Guido