* add --logfile option

Config.cpp

@@ -111,6 +111,7 @@ namespace config {
       ("tunconf",   value<std::string>()->default_value(""),     "Path to config with tunnels list and options (default: try ~/.i2pd/tunnels.cfg or /var/lib/i2pd/tunnels.cfg)")
       ("pidfile",   value<std::string>()->default_value(""),     "Write pidfile to given path")
       ("log",       value<bool>()->zero_tokens(),                "Write logs to file instead stdout")
+      ("logfile",   value<std::string>()->default_value(""),     "Path to logfile (stdout if not set, autodetect if daemon)")
       ("loglevel",  value<std::string>()->default_value("info"), "Set the minimal level of log messages (debug, info, warn, error)")
       ("host",      value<std::string>()->default_value(""),     "External IP (deprecated)")
       ("port,p",    value<uint16_t>()->default_value(4567),      "Port to listen for incoming connections")

Daemon.cpp

@@ -116,22 +116,25 @@ namespace i2p
 			
 		bool Daemon_Singleton::start()
 		{
-			// initialize log			
 			if (isLogging)
 			{
-				if (isDaemon)
-				{
-					std::string logfile_path = IsService () ? "/var/log" : i2p::util::filesystem::GetDataDir().string();
+				// set default to stdout
+				std::string logfile  = ""; i2p::config::GetOption("logfile",  logfile);
+				std::string loglevel = ""; i2p::config::GetOption("loglevel", loglevel);
+				if (isDaemon && logfile == "") {
+					// can't log to stdout, use autodetect of logfile
+					if (IsService ()) {
+					  logfile = "/var/log";
+					} else {
+					  logfile = i2p::util::filesystem::GetDataDir().string();
+					}
 #ifndef _WIN32
-					logfile_path.append("/i2pd.log");
+					logfile.append("/i2pd.log");
 #else
-					logfile_path.append("\\i2pd.log");
+					logfile.append("\\i2pd.log");
 #endif
-					StartLog (logfile_path);
-				} else {
-					StartLog (""); // write to stdout
 				}
-				std::string loglevel; i2p::config::GetOption("loglevel", loglevel);
+				StartLog (logfile);
 				g_Log->SetLogLevel(loglevel);
 			}