[libvirt PATCH 3/9] conf: put interface <backend> parsing/formatting separate functions

In preparation for adding more stuff to <backend>.

Signed-off-by: Laine Stump &lt;laine(a)redhat.com&gt;
---

I wanted virDomainNetBackendParseXML to simply take a
virDomainNetBackend*, but there is a test case specifically checking
to be sure that backend/vhost isn't parsed if the interface isn't
virtio. Silently Ignoring+stripping this during parse is arguably the
wrong thing to do - either we should log an error on validation, or we
should just leave it in (it's only ever used if the interface is
virtio), but that's a problem for another day.

(Opinions on the proper thing to do are welcome - since it's currently
always stripped out on parse, I *think* I could begin checking for it
during validation - there is no way that old code could leave the
backend/vhost for a non-virtio interface in any domain xml written to
disk. Alternately would could just allow it to be parsed and
faithfully format it even when the interface isn't virtio, and not log
any error.)

 src/conf/domain_conf.c | 57 +++++++++++++++++++++++++++++++-----------
 1 file changed, 42 insertions(+), 15 deletions(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 30b0cef131..9502f2ebab 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -8970,6 +8970,26 @@ virDomainNetDefParseXMLDriver(virDomainNetDef *def,
 }
 
 
+static int
+virDomainNetBackendParseXML(xmlNodePtr node,
+                            virDomainNetDef *def)
+{
+    g_autofree char *tap = virXMLPropString(node, "tap");
+    g_autofree char *vhost = virXMLPropString(node, "vhost");
+
+    if (tap)
+        def->backend.tap = virFileSanitizePath(tap);
+
+    if (vhost &&
+        def->type != VIR_DOMAIN_NET_TYPE_HOSTDEV &&
+        virDomainNetIsVirtioModel(def)) {
+        def->backend.vhost = virFileSanitizePath(vhost);
+    }
+
+    return 0;
+}
+
+
 static int
 virDomainNetDefParseXMLRequireSource(virDomainNetDef *def,
                                      xmlNodePtr source_node)
@@ -9016,6 +9036,7 @@ virDomainNetDefParseXML(virDomainXMLOption *xmlopt,
     xmlNodePtr mac_node = NULL;
     xmlNodePtr target_node = NULL;
     xmlNodePtr coalesce_node = NULL;
+    xmlNodePtr backend_node = NULL;
     VIR_XPATH_NODE_AUTORESTORE(ctxt)
     int rv;
     g_autofree char *macaddr = NULL;
@@ -9319,9 +9340,6 @@ virDomainNetDefParseXML(virDomainXMLOption *xmlopt,
         (virNetDevVlanParse(vlan_node, ctxt, &def->vlan) < 0))
         return NULL;
 
-    if ((tap = virXPathString("string(./backend/@tap)", ctxt)))
-        def->backend.tap = virFileSanitizePath(tap);
-
     if ((mac_node = virXPathNode("./mac", ctxt))) {
         if ((macaddr = virXMLPropString(mac_node, "address"))) {
             if (virMacAddrParse((const char *)macaddr, &def->mac) < 0) {
@@ -9376,12 +9394,9 @@ virDomainNetDefParseXML(virDomainXMLOption *xmlopt,
     if (virDomainNetDefParseXMLDriver(def, ctxt) < 0)
         return NULL;
 
-    if (def->type != VIR_DOMAIN_NET_TYPE_HOSTDEV &&
-        virDomainNetIsVirtioModel(def)) {
-        g_autofree char *vhost = virXPathString("string(./backend/@vhost)",
ctxt);
-
-        if (vhost)
-            def->backend.vhost = virFileSanitizePath(vhost);
+    if ((backend_node = virXPathNode("./backend", ctxt)) &&
+        virDomainNetBackendParseXML(backend_node, def) < 0) {
+        return NULL;
     }
 
     def->linkstate = VIR_DOMAIN_NET_INTERFACE_LINK_STATE_DEFAULT;
@@ -23255,6 +23270,21 @@ virDomainNetTeamingInfoFormat(virDomainNetTeamingInfo *teaming,
 }
 
 
+static void
+virDomainNetBackendFormat(virBuffer *buf,
+                          virDomainNetBackend *backend)
+{
+
+    if (!(backend->tap || backend->vhost))
+        return;
+
+    virBufferAddLit(buf, "<backend");
+    virBufferEscapeString(buf, " tap='%s'", backend->tap);
+    virBufferEscapeString(buf, " vhost='%s'", backend->vhost);
+    virBufferAddLit(buf, "/>\n");
+}
+
+
 int
 virDomainNetDefFormat(virBuffer *buf,
                       virDomainNetDef *def,
@@ -23555,12 +23585,9 @@ virDomainNetDefFormat(virBuffer *buf,
             virXMLFormatElement(buf, "driver", &driverAttrBuf,
&driverChildBuf);
         }
     }
-    if (def->backend.tap || def->backend.vhost) {
-        virBufferAddLit(buf, "<backend");
-        virBufferEscapeString(buf, " tap='%s'",
def->backend.tap);
-        virBufferEscapeString(buf, " vhost='%s'",
def->backend.vhost);
-        virBufferAddLit(buf, "/>\n");
-    }
+
+    virDomainNetBackendFormat(buf, &def->backend);
+
     if (def->filter) {
         if (virNWFilterFormatParamAttributes(buf, def->filterparams,
                                              def->filter) < 0)
-- 
2.38.1