Implemented support for writing a PID file.

base/application.cpp

@@ -69,9 +69,9 @@ Application::~Application(void)
 
 #ifdef _WIN32
 	WSACleanup();
-#else /* _WIN32 */
-	//lt_dlexit();
 #endif /* _WIN32 */
+
+	ClosePidFile();
 }
 
 /**
@@ -406,3 +406,41 @@ int Application::Run(int argc, char **argv)
 
 	return result;
 }
+
+void Application::UpdatePidFile(const string& filename)
+{
+	ClosePidFile();
+
+	/* There's just no sane way of getting a file descriptor for a
+	 * C++ ofstream which is why we're using FILEs here. */
+	m_PidFile = fopen(filename.c_str(), "w");
+
+	if (m_PidFile == NULL)
+		throw runtime_error("Could not open PID file '" + filename + "'");
+
+	if (flock(fileno(m_PidFile), LOCK_EX | LOCK_NB) < 0) {
+		ClosePidFile();
+
+		throw runtime_error("Another instance of the application is "
+		    "already running. Remove the '" + filename + "' file if "
+		    "you're certain that this is not the case.");
+	}
+
+#ifndef _WIN32
+	pid_t pid = getpid();
+#else /* _WIN32 */
+	DWORD pid = GetCurrentProcessId();
+#endif /* _WIN32 */
+
+	fprintf(m_PidFile, "%d", pid);
+	fflush(m_PidFile);
+}
+
+void Application::ClosePidFile(void)
+{
+	if (m_PidFile != NULL)
+		fclose(m_PidFile);
+
+	m_PidFile = NULL;
+}
+

base/application.h

@@ -56,6 +56,9 @@ public:
 
 	static bool IsMainThread(void);
 
+	void UpdatePidFile(const string& filename);
+	void ClosePidFile(void);
+
 protected:
 	void RunEventLoop(void);
 	string GetExePath(void) const;
@@ -68,6 +71,7 @@ private:
 	map< string, shared_ptr<Component> > m_Components; /**< Components that
 					were loaded by the application. */
 	vector<string> m_Arguments; /**< Command-line arguments */
+	FILE *m_PidFile; /**< The PID file */
 	static bool m_Debugging; /**< Whether debugging is enabled. */
 	static boost::thread::id m_MainThreadID; /**< ID of the main thread. */
 

base/unix.h

@@ -34,6 +34,7 @@
 #include <signal.h>
 #include <libgen.h>
 #include <syslog.h>
+#include <sys/file.h>
 
 void Sleep(unsigned long milliseconds);
 

icinga/icingaapplication.cpp

@@ -28,6 +28,8 @@
 
 using namespace icinga;
 
+const string IcingaApplication::PidFilename = "icinga.pid";
+
 /**
  * The entry point for the Icinga application.
  *
@@ -47,6 +49,8 @@ int IcingaApplication::Main(const vector<string>& args)
 
 	time(&m_StartTime);
 
+	UpdatePidFile(PidFilename);
+
 	if (args.size() < 2) {
 		stringstream msgbuf;
 		msgbuf << "Syntax: " << args[0] << " [-S] [-L logfile] [-d] [--] <config-file>";
@@ -170,7 +174,9 @@ int IcingaApplication::Main(const vector<string>& args)
 
 	if (daemonize) {
 		Logger::Write(LogInformation, "icinga", "Daemonizing.");
+		ClosePidFile();
 		Utility::Daemonize();
+		UpdatePidFile(PidFilename);
 		Logger::UnregisterLogger(consoleLogger);
 	}
 

icinga/icingaapplication.h

@@ -45,6 +45,8 @@ public:
 
 	time_t GetStartTime(void) const;
 
+	static const string PidFilename;
+
 private:
 	string m_CertificateFile;
 	string m_CAFile;