util: Add helper to convert libxml2 nodes to a string

src/libvirt_private.syms

@@ -2092,6 +2092,7 @@ virUUIDParse;
 
 # util/virxml.h
 virXMLChildElementCount;
+virXMLNodeToString;
 virXMLParseHelper;
 virXMLPickShellSafeComment;
 virXMLPropString;

src/util/virxml.c

@@ -895,3 +895,36 @@ virXMLChildElementCount(xmlNodePtr node)
     }
     return ret;
 }
+
+
+/**
+ * virXMLNodeToString: convert an XML node ptr to an XML string
+ *
+ * Returns the XML string of the document or NULL on error.
+ * The caller has to free the string.
+ */
+char *
+virXMLNodeToString(xmlDocPtr doc,
+                   xmlNodePtr node)
+{
+     xmlBufferPtr xmlbuf = NULL;
+     char *ret = NULL;
+
+     if (!(xmlbuf = xmlBufferCreate())) {
+         virReportOOMError();
+         return NULL;
+     }
+
+     if (xmlNodeDump(xmlbuf, doc, node, 0, 1) == 0) {
+         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                        _("failed to convert the XML node tree"));
+         goto cleanup;
+     }
+
+     ignore_value(VIR_STRDUP(ret, (const char *)xmlBufferContent(xmlbuf)));
+
+cleanup:
+     xmlBufferFree(xmlbuf);
+
+     return ret;
+}

src/util/virxml.h

@@ -163,4 +163,6 @@ int virXMLSaveFile(const char *path,
                    const char *warnCommand,
                    const char *xml);
 
+char *virXMLNodeToString(xmlDocPtr doc, xmlNodePtr node);
+
 #endif                          /* __VIR_XML_H__ */