virsh-domain-monitor: Refactor cmdDomIfGetLink

The domif-getlink command did not terminate successfully when the
interface state was found. As the code used old and too complex approach
to do the job, this patch refactors it and fixes the bug.

tools/virsh-domain-monitor.c

@@ -663,25 +663,23 @@ cmdDomIfGetLink(vshControl *ctl, const vshCmd *cmd)
 {
     virDomainPtr dom;
     const char *iface = NULL;
-    int flags = 0;
     char *state = NULL;
-    char *value = NULL;
+    char *xpath = NULL;
     virMacAddr macaddr;
-    const char *element;
-    const char *attr;
-    bool ret = false;
-    int i;
-    char *desc;
+    char macstr[VIR_MAC_STRING_BUFLEN] = "";
+    char *desc = NULL;
     xmlDocPtr xml = NULL;
     xmlXPathContextPtr ctxt = NULL;
-    xmlNodePtr cur = NULL;
-    xmlXPathObjectPtr obj = NULL;
+    xmlNodePtr *interfaces = NULL;
+    int ninterfaces;
+    unsigned int flags = 0;
+    bool ret = false;
 
-    if (!(dom = vshCommandOptDomain(ctl, cmd, NULL)))
+    if (vshCommandOptStringReq(ctl, cmd, "interface", &iface) < 0)
         return false;
 
-    if (vshCommandOptStringReq(ctl, cmd, "interface", &iface) < 0)
-        goto cleanup;
+    if (!(dom = vshCommandOptDomain(ctl, cmd, NULL)))
+        return false;
 
     if (vshCommandOptBool(cmd, "config"))
         flags = VIR_DOMAIN_XML_INACTIVE;
@@ -691,72 +689,50 @@ cmdDomIfGetLink(vshControl *ctl, const vshCmd *cmd)
         goto cleanup;
     }
 
-    xml = virXMLParseStringCtxt(desc, _("(domain_definition)"), &ctxt);
-    VIR_FREE(desc);
-    if (!xml) {
+    if (!(xml = virXMLParseStringCtxt(desc, _("(domain_definition)"), &ctxt))) {
         vshError(ctl, _("Failed to parse domain description xml"));
         goto cleanup;
     }
 
-    obj = xmlXPathEval(BAD_CAST "/domain/devices/interface", ctxt);
-    if (obj == NULL || obj->type != XPATH_NODESET ||
-        obj->nodesetval == NULL || obj->nodesetval->nodeNr == 0) {
-        vshError(ctl, _("Failed to extract interface information or no interfaces found"));
+    /* normalize the mac addr */
+    if (virMacAddrParse(iface, &macaddr) == 0)
+        virMacAddrFormat(&macaddr, macstr);
+
+    if (virAsprintf(&xpath, "/domain/devices/interface[(mac/@address = '%s') or "
+                            "                          (target/@dev = '%s')]",
+                           macstr, iface) < 0) {
+        virReportOOMError();
         goto cleanup;
     }
 
-    if (virMacAddrParse(iface, &macaddr) == 0) {
-        element = "mac";
-        attr = "address";
-    } else {
-        element = "target";
-        attr = "dev";
+    if ((ninterfaces = virXPathNodeSet(xpath, ctxt, &interfaces)) < 0) {
+        vshError(ctl, _("Failed to extract interface information"));
+        goto cleanup;
     }
 
-    /* find interface with matching mac addr */
-    for (i = 0; i < obj->nodesetval->nodeNr; i++) {
-        cur = obj->nodesetval->nodeTab[i]->children;
-
-        while (cur) {
-            if (cur->type == XML_ELEMENT_NODE &&
-                xmlStrEqual(cur->name, BAD_CAST element)) {
-
-                value = virXMLPropString(cur, attr);
+    if (ninterfaces != 1) {
+        if (macstr[0])
+            vshError(ctl, _("Interface (mac: %s) not found."), macstr);
+        else
+            vshError(ctl, _("Interface (dev: %s) not found."), iface);
 
-                if (STRCASEEQ(value, iface)) {
-                    VIR_FREE(value);
-                    goto hit;
-                }
-                VIR_FREE(value);
-            }
-            cur = cur->next;
-        }
+        goto cleanup;
     }
 
-    vshError(ctl, _("Interface (%s: %s) not found."), element, iface);
-    goto cleanup;
-
-hit:
-    cur = obj->nodesetval->nodeTab[i]->children;
-    while (cur) {
-        if (cur->type == XML_ELEMENT_NODE &&
-            xmlStrEqual(cur->name, BAD_CAST "link")) {
-
-            state = virXMLPropString(cur, "state");
-            vshPrint(ctl, "%s %s", iface, state);
-            VIR_FREE(state);
+    ctxt->node = interfaces[0];
 
-            goto cleanup;
-        }
-        cur = cur->next;
-    }
-
-    /* attribute not found */
-    vshPrint(ctl, "%s default", iface);
+    if ((state = virXPathString("string(./link/@state)", ctxt)))
+        vshPrint(ctl, "%s %s", iface, state);
+    else
+        vshPrint(ctl, "%s default", iface);
 
     ret = true;
+
 cleanup:
-    xmlXPathFreeObject(obj);
+    VIR_FREE(desc);
+    VIR_FREE(state);
+    VIR_FREE(interfaces);
+    VIR_FREE(xpath);
     xmlXPathFreeContext(ctxt);
     xmlFreeDoc(xml);
     virDomainFree(dom);