configuration: support multiple configuration files

src/configuration.cpp

@@ -18,6 +18,7 @@
  *   51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.              *
  ***************************************************************************/
 
+#include <algorithm>
 #include <boost/filesystem/operations.hpp>
 #include <boost/program_options.hpp>
 #include <iostream>
@@ -27,6 +28,7 @@
 #include "config.h"
 #include "mpdpp.h"
 #include "settings.h"
+#include "utility/string.h"
 
 namespace po = boost::program_options;
 
@@ -37,23 +39,45 @@ namespace {
 
 const char *env_home;
 
+std::string xdg_config_home()
+{
+	std::string result;
+	const char *env_xdg_config_home = getenv("XDG_CONFIG_HOME");
+	if (env_xdg_config_home == nullptr)
+		result = "~/.config/ncmpcpp/";
+	else
+	{
+		result = env_xdg_config_home;
+		if (!result.empty() && result.back() != '/')
+			result += "/";
+	}
+	return result;
+}
+
 }
 
 void expand_home(std::string &path)
 {
+	assert(env_home != nullptr);
 	if (!path.empty() && path[0] == '~')
 		path.replace(0, 1, env_home);
 }
 
 bool configure(int argc, char **argv)
 {
-	std::string bindings_path, config_path;
+	const std::vector<std::string> default_config_paths = {
+		"~/.ncmpcpp/config",
+		xdg_config_home() + "config"
+	};
+
+	std::string bindings_path;
+	std::vector<std::string> config_paths;
 
 	po::options_description options("Options");
 	options.add_options()
 		("host,h", po::value<std::string>()->default_value("localhost"), "connect to server at host")
 		("port,p", po::value<int>()->default_value(6600), "connect to server at port")
-		("config,c", po::value<std::string>(&config_path)->default_value("~/.ncmpcpp/config"), "specify configuration file")
+		("config,c", po::value<std::vector<std::string>>(&config_paths)->default_value(default_config_paths, join<std::string>(default_config_paths, " AND ")), "specify configuration file(s)")
 		("bindings,b", po::value<std::string>(&bindings_path)->default_value("~/.ncmpcpp/bindings"), "specify bindings file")
 		("screen,s", po::value<std::string>(), "specify initial screen")
 		("slave-screen,S", po::value<std::string>(), "specify initial slave screen")
@@ -120,7 +144,6 @@ bool configure(int argc, char **argv)
 		}
 
 		po::notify(vm);
-
 		// get home directory
 		env_home = getenv("HOME");
 		if (env_home == nullptr)
@@ -130,8 +153,8 @@ bool configure(int argc, char **argv)
 		}
 
 		// read configuration
-		expand_home(config_path);
-		if (Config.read(config_path) == false)
+		std::for_each(config_paths.begin(), config_paths.end(), expand_home);
+		if (Config.read(config_paths) == false)
 			exit(1);
 
 		// if bindings file was not specified, use the one from main directory.

src/settings.cpp

@@ -173,7 +173,7 @@ option_parser::worker buffer(NC::Buffer &arg, ValueT &&value, TransformT &&map)
 
 }
 
-bool Configuration::read(const std::string &config_path)
+bool Configuration::read(const std::vector<std::string> &config_paths)
 {
 	std::string mpd_host;
 	unsigned mpd_port;
@@ -653,8 +653,16 @@ bool Configuration::read(const std::string &config_path)
 		active_window_border, NC::Border::Red
 	));
 
-	std::ifstream f(config_path);
-	return p.run(f);
+	return std::all_of(
+		config_paths.begin(),
+		config_paths.end(),
+		[&p](const std::string &config_path) {
+			std::ifstream f(config_path);
+			if (f.is_open())
+				std::clog << "Reading configuration from " << config_path << "...\n";
+			return p.run(f);
+		}
+	);
 }
 
 /* vim: set tabstop=4 softtabstop=4 shiftwidth=4 noexpandtab : */

src/settings.h

@@ -53,7 +53,7 @@ struct Configuration
 	: playlist_disable_highlight_delay(0), visualizer_sync_interval(0)
 	{ }
 
-	bool read(const std::string &config_path);
+	bool read(const std::vector<std::string> &config_paths);
 
 	std::string ncmpcpp_directory;
 	std::string lyrics_directory;

src/utility/option_parser.h

@@ -106,8 +106,18 @@ struct option_parser
 			m_defined = true;
 		}
 
-		bool defined() const { return m_defined; }
-		void run_default() const { m_default(); }
+		bool defined() const
+		{
+			return m_defined;
+		}
+
+		void run_default()
+		{
+			if (m_defined)
+				throw std::runtime_error("option already defined");
+			m_default();
+			m_defined = true;
+		}
 
 	private:
 		bool m_defined;

src/utility/string.h

@@ -32,8 +32,8 @@ template <size_t N> size_t const_strlen(const char (&)[N]) {
 }
 
 // it's present in boost for std::string, but we want more general version.
-template <typename CollectionT, typename StringT>
-StringT join(CollectionT &&collection, StringT &&separator)
+template <typename StringT, typename CollectionT>
+StringT join(const CollectionT &collection, const StringT &separator)
 {
 	StringT result;
 	auto first = std::begin(collection), last = std::end(collection);