While reviewing Rich last patch I was afraid that virXPathNodeSet() could return -1 when doing an evaluation failure. It is based on xmlXPathEval() from libxml2 whose behaviour is to possibly return NULL on XPath evaluation failure independantly of the kind of failure: http://xmlsoft.org/html/libxml-xpath.html#xmlXPathEval I suggest to apply this patch to make sure we always return 0 unless the returned XPath type is of the wrong type (meaning the query passed didn't evaluate to a node set and code must be fixed)

diff --git a/src/util/xml.c b/src/util/xml.c index 4118d2a..4fa443d 100644 --- a/src/util/xml.c +++ b/src/util/xml.c @@ -490,11 +490,16 @@ virXPathNodeSet(virConnectPtr conn, relnode = ctxt->node; obj = xmlXPathEval(BAD_CAST xpath, ctxt); ctxt->node = relnode; - if ((obj == NULL) || (obj->type != XPATH_NODESET) || - (obj->nodesetval == NULL) || (obj->nodesetval->nodeNr < 0)) { + if (obj == NULL) + return(0); + if (obj->type != XPATH_NODESET) { xmlXPathFreeObject(obj); return (-1); } + if ((obj->nodesetval == NULL) || (obj->nodesetval->nodeNr < 0)) { + xmlXPathFreeObject(obj); + return (0); + } ret = obj->nodesetval->nodeNr; if (list != NULL && ret) {