Falco engine changes to support multiple files in rule load results

The methods that throw exceptions from stringified results need to
additionally pass a rules_contents_t struct. This also meant that they
need to call the filename + content version of load_rules.

To avoid some duplicate code between the two load_rules_file methods,
move the work of opening the file into a private method
read_file(). It can throw an exception, which is passed through for
the void return method and caught + converted into a load_result error
for the method that returns a load_result.

Also, to avoid duplicate code between the void load_rules and
load_rules_file methods, add a private method interpret_load_result()
which throws an exception if the result has an error and prints
warnings otherwise if verbose is true.

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

userspace/engine/falco_engine.h

@@ -233,6 +233,17 @@ public:
 		std::string& err);
 
 private:
+
+	// Throws falco_exception if the file can not be read
+	void read_file(const std::string& filename, std::string& contents);
+
+	// For load_rules methods that throw exceptions on error,
+	// interpret a load_result and throw an exception if needed.
+	void interpret_load_result(std::unique_ptr<falco::load_result>& res,
+				   const std::string& rules_filename,
+				   const std::string& rules_content,
+				   bool verbose);
+
 	indexed_vector<falco_source> m_sources;
 
 	falco_source* find_source(std::size_t index);