Add improved field outputting

Support the notion of a message for all fields in a single class, and
making sure it's wrapped as well as the other fields.

This is used to display a single message about how indexing working for
ka.* filter fields and what IDX_ALLOWED/IDX_NUMERIC/IDX_KEY means,
rather than repeating the same text over and over in every field.

The wrapping is handled by a function falco::utils::wrap_text.

Signed-off-by: Mark Stemm <mark.stemm@gmail.com>

userspace/engine/falco_utils.cpp

@@ -0,0 +1,55 @@
+/*
+Copyright (C) 2016-2018 Draios Inc dba Sysdig.
+
+This file is part of falco.
+
+Licensed 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 "falco_utils.h"
+
+namespace falco
+{
+
+namespace utils
+{
+
+std::string wrap_text(const std::string &str, uint32_t initial_pos, uint32_t indent, uint32_t line_len)
+{
+	std::string ret;
+
+	size_t len = str.size();
+
+	for(uint32_t l = 0; l < len; l++)
+	{
+		if(l % (line_len - indent) == 0 && l != 0)
+		{
+			ret += "\n";
+
+			for(uint32_t m = 0; m < indent; m++)
+			{
+				ret += " ";
+			}
+		}
+		ret += str.at(l);
+	}
+
+	ret += "\n";
+
+	return ret;
+}
+
+} // namespace utils
+
+} // namespace falco