Function getXpathResult

lib/common/xml.c:2691–2745

}

xmlNode *
getXpathResult(xmlXPathObjectPtr xpathObj, int index) 
{
    xmlNode *match = NULL;
    CRM_CHECK(index >= 0, return NULL);
    CRM_CHECK(xpathObj != NULL, return NULL);

    if(index >= xpathObj->nodesetval->nodeNr) {
	crm_err("Requested index %d of only %d items", index, xpathObj->nodesetval->nodeNr);
	return NULL;
    }
    
    match = xpathObj->nodesetval->nodeTab[index];
    CRM_CHECK(match != NULL, return NULL);

    /*
     * From xpath2.c
     *
     * All the elements returned by an XPath query are pointers to
     * elements from the tree *except* namespace nodes where the XPath
     * semantic is different from the implementation in libxml2 tree.
     * As a result when a returned node set is freed when
     * xmlXPathFreeObject() is called, that routine must check the
     * element type. But node from the returned set may have been removed
     * by xmlNodeSetContent() resulting in access to freed data.
     * This can be exercised by running
     *       valgrind xpath2 test3.xml '//discarded' discarded
     * There is 2 ways around it:
     *   - make a copy of the pointers to the nodes from the result set 
     *     then call xmlXPathFreeObject() and then modify the nodes
     * or
     *   - remove the reference to the modified nodes from the node set
     *     as they are processed, if they are not namespace nodes.
     */
    if (xpathObj->nodesetval->nodeTab[index]->type != XML_NAMESPACE_DECL) {
	xpathObj->nodesetval->nodeTab[index] = NULL;
    }

    if(match->type == XML_DOCUMENT_NODE) {
	/* Will happen if section = '/' */
	match = match->children;

    } else if(match->type != XML_ELEMENT_NODE
	      && match->parent
	      && match->parent->type == XML_ELEMENT_NODE) {
	/* reurning the parent instead */
	match = match->parent;
	
    } else if(match->type != XML_ELEMENT_NODE) {
	/* We only support searching nodes */
	crm_err("We only support %d not %d", XML_ELEMENT_NODE, match->type);
	match = NULL;
    }
    return match;
}

/* the caller needs to check if the result contains a xmlDocPtr or xmlNodePtr */
xmlXPathObjectPtr