virxml: Introduce and use virXMLFormatMetadata()

So far, we have to places where we format <metadata/> into XMLs:
domain and network. Bot places share the same code. Move it into
a helper function and just call it from those places.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>

src/conf/domain_conf.c

@@ -27806,27 +27806,8 @@ virDomainDefFormatInternalSetRootName(virDomainDef *def,
     virBufferEscapeString(buf, "<description>%s</description>\n",
                           def->description);
 
-    if (def->metadata) {
-        g_autoptr(xmlBuffer) xmlbuf = NULL;
-        int oldIndentTreeOutput = xmlIndentTreeOutput;
-
-        /* Indentation on output requires that we previously set
-         * xmlKeepBlanksDefault to 0 when parsing; also, libxml does 2
-         * spaces per level of indentation of intermediate elements,
-         * but no leading indentation before the starting element.
-         * Thankfully, libxml maps what looks like globals into
-         * thread-local uses, so we are thread-safe.  */
-        xmlIndentTreeOutput = 1;
-        xmlbuf = virXMLBufferCreate();
-
-        if (xmlNodeDump(xmlbuf, def->metadata->doc, def->metadata,
-                        virBufferGetIndent(buf) / 2, 1) < 0) {
-            xmlIndentTreeOutput = oldIndentTreeOutput;
-            return -1;
-        }
-        virBufferAsprintf(buf, "%s\n", (char *) xmlBufferContent(xmlbuf));
-        xmlIndentTreeOutput = oldIndentTreeOutput;
-    }
+    if (virXMLFormatMetadata(buf, def->metadata) < 0)
+        return -1;
 
     if (virDomainDefHasMemoryHotplug(def)) {
         virBufferAsprintf(buf,

src/conf/network_conf.c

@@ -2486,27 +2486,8 @@ virNetworkDefFormatBuf(virBuffer *buf,
     virUUIDFormat(uuid, uuidstr);
     virBufferAsprintf(buf, "<uuid>%s</uuid>\n", uuidstr);
 
-    if (def->metadata) {
-        g_autoptr(xmlBuffer) xmlbuf = NULL;
-        int oldIndentTreeOutput = xmlIndentTreeOutput;
-
-        /* Indentation on output requires that we previously set
-         * xmlKeepBlanksDefault to 0 when parsing; also, libxml does 2
-         * spaces per level of indentation of intermediate elements,
-         * but no leading indentation before the starting element.
-         * Thankfully, libxml maps what looks like globals into
-         * thread-local uses, so we are thread-safe.  */
-        xmlIndentTreeOutput = 1;
-        xmlbuf = virXMLBufferCreate();
-
-        if (xmlNodeDump(xmlbuf, def->metadata->doc, def->metadata,
-                        virBufferGetIndent(buf) / 2, 1) < 0) {
-            xmlIndentTreeOutput = oldIndentTreeOutput;
-            return -1;
-        }
-        virBufferAsprintf(buf, "%s\n", (char *) xmlBufferContent(xmlbuf));
-        xmlIndentTreeOutput = oldIndentTreeOutput;
-    }
+    if (virXMLFormatMetadata(buf, def->metadata) < 0)
+        return -1;
 
     if (def->forward.type != VIR_NETWORK_FORWARD_NONE) {
         const char *dev = NULL;

src/libvirt_private.syms

@@ -3555,6 +3555,7 @@ virXMLCheckIllegalChars;
 virXMLExtractNamespaceXML;
 virXMLFormatElement;
 virXMLFormatElementEmpty;
+virXMLFormatMetadata;
 virXMLNewNode;
 virXMLNodeContentString;
 virXMLNodeNameEqual;

src/util/virxml.c

@@ -1707,6 +1707,49 @@ virXMLFormatElement(virBuffer *buf,
 }
 
 
+/**
+ * virXMLFormatMetadata:
+ * @buf: the parent buffer where the element will be placed
+ * @metadata: pointer to metadata node
+ *
+ * Helper to format metadata element. If @metadata is NULL then
+ * this function is a NOP.
+ *
+ * Returns: 0 on success,
+ *         -1 otherwise.
+ */
+int
+virXMLFormatMetadata(virBuffer *buf,
+                     xmlNodePtr metadata)
+{
+    g_autoptr(xmlBuffer) xmlbuf = NULL;
+    int oldIndentTreeOutput = xmlIndentTreeOutput;
+
+    if (!metadata)
+        return 0;
+
+    /* Indentation on output requires that we previously set
+     * xmlKeepBlanksDefault to 0 when parsing; also, libxml does 2
+     * spaces per level of indentation of intermediate elements,
+     * but no leading indentation before the starting element.
+     * Thankfully, libxml maps what looks like globals into
+     * thread-local uses, so we are thread-safe.  */
+    xmlIndentTreeOutput = 1;
+    xmlbuf = virXMLBufferCreate();
+
+    if (xmlNodeDump(xmlbuf, metadata->doc, metadata,
+                    virBufferGetIndent(buf) / 2, 1) < 0) {
+        xmlIndentTreeOutput = oldIndentTreeOutput;
+        return -1;
+    }
+
+    virBufferAsprintf(buf, "%s\n", (char *) xmlBufferContent(xmlbuf));
+    xmlIndentTreeOutput = oldIndentTreeOutput;
+
+    return 0;
+}
+
+
 void
 virXPathContextNodeRestore(virXPathContextNodeSave *save)
 {

src/util/virxml.h

@@ -333,6 +333,9 @@ virXMLFormatElementEmpty(virBuffer *buf,
                          virBuffer *attrBuf,
                          virBuffer *childBuf);
 
+int
+virXMLFormatMetadata(virBuffer *buf,
+                     xmlNodePtr metadata);
 
 struct _virXPathContextNodeSave {
     xmlXPathContextPtr ctxt;