new(userspace/falco): file output C++ impl

Signed-off-by: Leonardo Grasso <me@leonardograsso.com>

userspace/falco/falco_outputs_file.cpp

@@ -0,0 +1,64 @@
+/*
+Copyright (C) 2020 The Falco Authors
+
+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_outputs_file.h"
+#include <iostream>
+#include <fstream>
+#include "banned.h" // This raises a compilation error when certain functions are used
+
+void falco::outputs::output_file::open_file()
+{
+	if(!m_buffered)
+	{
+		m_outfile.rdbuf()->pubsetbuf(0, 0);
+	}
+	if(!m_outfile.is_open())
+	{
+		m_outfile.open(m_oc.options["filename"], fstream::app);
+	}
+}
+
+void falco::outputs::output_file::output_event(gen_event *evt, std::string &rule, std::string &source,
+					       falco_common::priority_type priority, std::string &format, std::string &msg)
+{
+	output_msg(priority, msg);
+}
+
+void falco::outputs::output_file::output_msg(falco_common::priority_type priority, std::string &msg)
+{
+	open_file();
+	m_outfile << msg + "\n";
+
+	if(m_oc.options["keep_alive"] != "true")
+	{
+		cleanup();
+	}
+}
+
+void falco::outputs::output_file::cleanup()
+{
+	if(m_outfile.is_open())
+	{
+		m_outfile.flush();
+		m_outfile.close();
+	}
+}
+
+void falco::outputs::output_file::reopen()
+{
+	cleanup();
+	open_file();
+}

userspace/falco/falco_outputs_file.h

@@ -0,0 +1,46 @@
+/*
+Copyright (C) 2020 The Falco Authors.
+
+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.
+*/
+
+#pragma once
+
+#include "falco_output.h"
+#include <iostream>
+#include <fstream>
+
+namespace falco
+{
+namespace outputs
+{
+
+class output_file : public output
+{
+	void output_event(gen_event *evt, std::string &rule, std::string &source,
+			  falco_common::priority_type priority, std::string &format, std::string &msg);
+
+	void output_msg(falco_common::priority_type priority, std::string &msg);
+
+	void cleanup();
+
+	void reopen();
+
+private:
+	void open_file();
+
+	std::ofstream m_outfile;
+};
+
+} // namespace outputs
+} // namespace falco