[GitHub] [nifi-minifi-cpp] szaszm commented on a change in pull request #976: MINIFICPP-1448 - CWEL JSON output

[GitBox <gi...@apache.org>]

szaszm commented on a change in pull request #976:
URL: https://github.com/apache/nifi-minifi-cpp/pull/976#discussion_r561927345



##########
File path: extensions/windows-event-log/wel/JSONUtils.cpp
##########
@@ -0,0 +1,170 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "JSONUtils.h"
+
+#include <vector>
+#include <string>
+#include <functional>
+
+#include <pugixml.hpp>
+
+#include "rapidjson/document.h"
+#include "rapidjson/writer.h"
+#include "rapidjson/stringbuffer.h"
+#include "rapidjson/prettywriter.h"
+
+#include "gsl/gsl-lite.hpp";
+
+namespace org {
+namespace apache {
+namespace nifi {
+namespace minifi {
+namespace wel {
+
+namespace {
+
+rapidjson::Value xmlElementToJSON(const pugi::xml_node& node, rapidjson::Document& doc) {
+  gsl_Expects(node.type() == pugi::xml_node_type::node_element);
+  rapidjson::Value object(rapidjson::kObjectType);
+  object.AddMember("name", rapidjson::StringRef(node.name()), doc.GetAllocator());
+  auto& attributes = object.AddMember("attributes", rapidjson::kObjectType, doc.GetAllocator())["attributes"];
+  for (const auto& attr : node.attributes()) {
+    attributes.AddMember(rapidjson::StringRef(attr.name()), rapidjson::StringRef(attr.value()), doc.GetAllocator());
+  }
+  auto& children = object.AddMember("children", rapidjson::kArrayType, doc.GetAllocator())["children"];
+  for (const auto& child : node.children()) {
+    if (child.type() == pugi::xml_node_type::node_element) {
+      children.PushBack(xmlElementToJSON(child, doc), doc.GetAllocator());
+    }
+  }
+  object.AddMember("text", rapidjson::StringRef(node.text().get()), doc.GetAllocator());
+  return object;
+}
+
+rapidjson::Value xmlDocumentToJSON(const pugi::xml_node& node, rapidjson::Document& doc) {
+  gsl_Expects(node.type() == pugi::xml_node_type::node_document);
+  rapidjson::Value children(rapidjson::kArrayType);
+  for (const auto& child : node.children()) {
+    if (child.type() == pugi::xml_node_type::node_element) {
+      children.PushBack(xmlElementToJSON(child, doc), doc.GetAllocator());
+    }
+  }
+  return children;
+}
+
+rapidjson::Document toJSONImpl(const pugi::xml_node& root, bool flatten) {
+  rapidjson::Document doc{rapidjson::kObjectType};
+
+  auto event_xml = root.child("Event");
+
+  {
+    auto system_xml = event_xml.child("System");
+    auto& system = flatten ? doc : doc.AddMember("System", rapidjson::kObjectType, doc.GetAllocator())["System"];
+
+    {
+      auto provider_xml = system_xml.child("Provider");
+      auto& provider = flatten ? doc : system.AddMember("Provider", rapidjson::kObjectType, doc.GetAllocator())["Provider"];
+      provider.AddMember("Name", rapidjson::StringRef(provider_xml.attribute("Name").value()), doc.GetAllocator());
+      provider.AddMember("Guid", rapidjson::StringRef(provider_xml.attribute("Guid").value()), doc.GetAllocator());
+    }
+
+    system.AddMember("EventID", rapidjson::StringRef(system_xml.child("EventID").text().get()), doc.GetAllocator());
+    system.AddMember("Version", rapidjson::StringRef(system_xml.child("Version").text().get()), doc.GetAllocator());
+    system.AddMember("Level", rapidjson::StringRef(system_xml.child("Level").text().get()), doc.GetAllocator());
+    system.AddMember("Task", rapidjson::StringRef(system_xml.child("Task").text().get()), doc.GetAllocator());
+    system.AddMember("Opcode", rapidjson::StringRef(system_xml.child("Opcode").text().get()), doc.GetAllocator());
+    system.AddMember("Keywords", rapidjson::StringRef(system_xml.child("Keywords").text().get()), doc.GetAllocator());
+
+    {
+      auto timeCreated_xml = system_xml.child("TimeCreated");
+      auto& timeCreated = flatten ? doc : system.AddMember("TimeCreated", rapidjson::kObjectType, doc.GetAllocator())["TimeCreated"];
+      timeCreated.AddMember("SystemTime", rapidjson::StringRef(timeCreated_xml.attribute("SystemTime").value()), doc.GetAllocator());
+    }
+
+    system.AddMember("EventRecordID", rapidjson::StringRef(system_xml.child("EventRecordID").text().get()), doc.GetAllocator());
+
+    {
+      auto correlation_xml = system_xml.child("Correlation");
+      auto& correlation = flatten ? doc : system.AddMember("Correlation", rapidjson::kObjectType, doc.GetAllocator())["Correlation"];
+      correlation.AddMember("ActivityID", rapidjson::StringRef(correlation_xml.attribute("ActivityID").value()), doc.GetAllocator());
+    }
+
+    {
+      auto execution_xml = system_xml.child("Execution");
+      auto& execution = flatten ? doc : system.AddMember("Execution", rapidjson::kObjectType, doc.GetAllocator())["Execution"];
+      execution.AddMember("ProcessID", rapidjson::StringRef(execution_xml.attribute("ProcessID").value()), doc.GetAllocator());
+      execution.AddMember("ThreadID", rapidjson::StringRef(execution_xml.attribute("ThreadID").value()), doc.GetAllocator());
+    }
+
+    system.AddMember("Channel", rapidjson::StringRef(system_xml.child("Channel").text().get()), doc.GetAllocator());
+    system.AddMember("Computer", rapidjson::StringRef(system_xml.child("Computer").text().get()), doc.GetAllocator());
+  }
+
+  {
+    auto eventData_xml = event_xml.child("EventData");
+    // create EventData subarray even if flatten requested
+    doc.AddMember("EventData", rapidjson::kArrayType, doc.GetAllocator());
+    for (const auto& data : eventData_xml.children()) {
+      auto name_attr = data.attribute("Name");
+      rapidjson::Value item(rapidjson::kObjectType);
+      item.AddMember("Name", rapidjson::StringRef(name_attr.value()), doc.GetAllocator());
+      item.AddMember("Content", rapidjson::StringRef(data.text().get()), doc.GetAllocator());
+      item.AddMember("Type", rapidjson::StringRef(data.name()), doc.GetAllocator());
+      // we need to query EventData because a reference to it wouldn't be stable, as we
+      // possibly add members to its parent which could result in reallocation
+      doc["EventData"].PushBack(item, doc.GetAllocator());
+      // check collision
+      if (flatten && !name_attr.empty() && !doc.HasMember(name_attr.value())) {
+        doc.AddMember(rapidjson::StringRef(name_attr.value()), rapidjson::StringRef(data.text().get()), doc.GetAllocator());

Review comment:
       If I understand correctly, using `rapidjson::StringRef` all over the place means that the returned json object is valid only as long as the original pugi xml object is valid and unchanged. If so, there should be a big loud warning on the function to warn the next caller about this.




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