Add support for writing a pidfile, drop user privs and forking into a daemon

8 files changed, 193 insertions, 2 deletions

diff --git a/project2/daemon/Jamfile.jam b/project2/daemon/Jamfile.jam
index 123e6fc..1a159c3 100644
--- a/project2/daemon/Jamfile.jam
+++ b/project2/daemon/Jamfile.jam
@@ -2,6 +2,7 @@ alias glibmm : : : :
 	<cflags>"`pkg-config --cflags glibmm-2.4`"
 	<linkflags>"`pkg-config --libs glibmm-2.4`"
 	;
+lib boost_filesystem : : <name>boost_filesystem ;
 exe p2daemon :
 	[ glob *.cpp ]
 	:
@@ -11,5 +12,6 @@ exe p2daemon :
 	<library>../common//p2common
 	<library>../cli//p2cli
 	<include>../../libmisc
+	<library>boost_filesystem
 	;
 
diff --git a/project2/daemon/p2daemonAppEngine.cpp b/project2/daemon/p2daemonAppEngine.cpp
index e5a1b3c..908b2b7 100644
--- a/project2/daemon/p2daemonAppEngine.cpp
+++ b/project2/daemon/p2daemonAppEngine.cpp
@@ -2,13 +2,25 @@
 #include <logger.h>
 #include <optionsSource.h>
 #include <dlfcn.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
 #include <options/flagSet.h>
 #include <options/showHelp.h>
+#include "pidfile.h"
+#include "tempPrivs.h"
 
 std::string DaemonAppEngine::daemonType;
 Glib::ustring DaemonAppEngine::reqPlatform;
 int DaemonAppEngine::periodicTimeout;
 DaemonAppEngine::SignalMap DaemonAppEngine::signalMap;
+boost::optional<uid_t> DaemonAppEngine::setUser;
+boost::optional<gid_t> DaemonAppEngine::setGroup;
+boost::optional<boost::filesystem::path> DaemonAppEngine::pidPath;
+bool DaemonAppEngine::daemonize;
+
+SimpleMessageException(NoSuchUser);
+SimpleMessageException(NoSuchGroup);
 
 DECLARE_OPTIONS(DaemonAppEngine, "Project2 Daemon options")
 ("help", new OptionFlagSet(&ShowHelpComponent::showHelp),
@@ -17,12 +29,32 @@ DECLARE_OPTIONS(DaemonAppEngine, "Project2 Daemon options")
 ("daemon.platform", Options::value(&reqPlatform), "Platform")
 ("daemon.periodicTimeout", Options::value(&periodicTimeout, 60),
  "Delay between occurrences of component periodic calls (default 60s)")
+("daemon.setuser", Options::functions([](const VariableType & un) {
+		auto passwd = getpwnam(un);
+		if (!passwd) {
+			throw NoSuchUser(un);
+		}
+		setUser = passwd->pw_uid;
+	}, []{ setUser = boost::optional<uid_t>(); }),
+ "Switch to this user on start up")
+("daemon.setgroup", Options::functions([](const VariableType & gn) {
+		auto group = getgrnam(gn);
+		if (!group) {
+			throw NoSuchGroup(gn);
+		}
+		setGroup = group->gr_gid;
+	}, []{ setGroup = boost::optional<uid_t>(); }),
+ "Switch to this group on start up")
+("daemon.pidfile", Options::functions([](const VariableType & p) { pidPath = p.as<std::string>(); }, []{ pidPath.reset(); }),
+ "Write a pid file to this path")
+("daemon.daemonize", new OptionFlagSet(&daemonize),
+ "Detach and run as daemon")
 END_OPTIONS(DaemonAppEngine);
 
 DaemonAppEngine::DaemonAppEngine(int argc, char ** argv) :
-	main_loop(Glib::MainLoop::create())
+	main_loop(Glib::MainLoop::create()),
+	daemonFactory(boost::bind(&DaemonLoader::create, DaemonLoader::getFor(daemonType), argc, argv))
 {
-	daemon = DaemonLoader::createNew(daemonType, argc, argv);
 	Glib::signal_timeout().connect_seconds(sigc::mem_fun(this, &DaemonAppEngine::periodicCallback), periodicTimeout);
 }
 
@@ -53,6 +85,12 @@ DaemonAppEngine::shutdown()
 void
 DaemonAppEngine::process()
 {
+	daemon = daemonFactory();
+	boost::shared_ptr<PidFile> pidFile;
+	if (DaemonAppEngine::pidPath) {
+		pidFile = boost::shared_ptr<PidFile>(new PidFile(*DaemonAppEngine::pidPath));
+	}
+	TempPrivs dropPrivs;
 	IgnoreSignal(SIGINT);
 	IgnoreSignal(SIGUSR1);
 	IgnoreSignal(SIGUSR2);
diff --git a/project2/daemon/p2daemonAppEngine.h b/project2/daemon/p2daemonAppEngine.h
index 0b16f70..84601bd 100644
--- a/project2/daemon/p2daemonAppEngine.h
+++ b/project2/daemon/p2daemonAppEngine.h
@@ -3,6 +3,7 @@
 
 #include <options.h>
 #include <boost/optional.hpp>
+#include <boost/filesystem/path.hpp>
 #include "lib/daemon.h"
 #include <thread>
 #include <glibmm/main.h>
@@ -19,6 +20,10 @@ class DaemonAppEngine {
 		static Glib::ustring reqPlatform;
 		static std::string daemonType;
 		static int periodicTimeout;
+		static boost::optional<uid_t> setUser;
+		static boost::optional<gid_t> setGroup;
+		static boost::optional<boost::filesystem::path> pidPath;
+		static bool daemonize;
 
 	protected:
 		typedef boost::function<void(int)> SignalFunc;
@@ -36,6 +41,8 @@ class DaemonAppEngine {
 		std::thread * evThread;
 		bool periodicCallback();
 		void shutdown();
+		typedef boost::function<DaemonPtr()> DaemonFactory;
+		const DaemonFactory daemonFactory;
 		DaemonPtr daemon;
 };
 
diff --git a/project2/daemon/p2daemonMain.cpp b/project2/daemon/p2daemonMain.cpp
index 20c4eb7..606945d 100644
--- a/project2/daemon/p2daemonMain.cpp
+++ b/project2/daemon/p2daemonMain.cpp
@@ -7,6 +7,39 @@
 
 SimpleMessageException(UnsupportedArguments);
 
+static
+void
+daemonize()
+{
+	pid_t pid = fork();
+	if (pid < 0) {
+		Logger()->messagebf(LOG_ERR, "%s: Failed to fork a new process (%d:%s)", __PRETTY_FUNCTION__, errno, strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+	if (pid > 0) {
+		exit(EXIT_SUCCESS);
+	}
+
+	if (setsid() < 0) {
+		Logger()->messagebf(LOG_ERR, "%s: Failed to set session Id (%d:%s)", __PRETTY_FUNCTION__, errno, strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	pid = fork();
+	if (pid < 0) {
+		Logger()->messagebf(LOG_ERR, "%s: Failed to fork a second new process (%d:%s)", __PRETTY_FUNCTION__, errno, strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+	if (pid > 0) {
+		exit(EXIT_SUCCESS);
+	}
+
+	// Other file handles presumably opened for a reason
+	close(0);
+	close(1);
+	close(2);
+}
+
 int
 main(int argc, char ** argv)
 {
@@ -17,6 +50,9 @@ main(int argc, char ** argv)
 	//Plugable::onAllComponents(boost::bind(&ComponentLoader::onBefore, _1));
 	
 	DaemonAppEngine dae(argc, argv);
+	if (DaemonAppEngine::daemonize) {
+		daemonize();
+	}
 	dae.process();
 
 	//Plugable::onAllComponents(boost::bind(&ComponentLoader::onIteration, _1));
diff --git a/project2/daemon/pidfile.cpp b/project2/daemon/pidfile.cpp
new file mode 100644
index 0000000..e2487c7
--- /dev/null
+++ b/project2/daemon/pidfile.cpp
@@ -0,0 +1,42 @@
+#include "pidfile.h"
+#include "p2daemonAppEngine.h"
+#include <unistd.h>
+#include <boost/lexical_cast.hpp>
+#include <boost/filesystem/operations.hpp>
+#include <boost/filesystem/fstream.hpp>
+
+SimpleMessageException(ChownFailed);
+
+PidFile::PidFile(const boost::filesystem::path & path) :
+	Path(path)
+{
+	auto pidDir = Path.parent_path();
+	if (!boost::filesystem::exists(pidDir)) {
+		boost::filesystem::create_directories(pidDir);
+		if (DaemonAppEngine::setGroup || DaemonAppEngine::setUser) {
+			if (chown(pidDir.string().c_str(),
+						DaemonAppEngine::setUser ? *DaemonAppEngine::setUser : -1,
+						DaemonAppEngine::setGroup ?  *DaemonAppEngine::setGroup : -1)) {
+				boost::filesystem::remove(pidDir);
+				throw ChownFailed(strerror(errno));
+			}
+		}
+	}
+
+	boost::filesystem::ofstream pf(Path);
+	pf << getpid();
+	if (DaemonAppEngine::setGroup || DaemonAppEngine::setUser) {
+		if (chown(Path.string().c_str(),
+				DaemonAppEngine::setUser ? *DaemonAppEngine::setUser : -1,
+				DaemonAppEngine::setGroup ?  *DaemonAppEngine::setGroup : -1)) {
+			boost::filesystem::remove(Path);
+			throw ChownFailed(strerror(errno));
+		}
+	}
+}
+
+PidFile::~PidFile()
+{
+	boost::filesystem::remove(Path);
+}
+
diff --git a/project2/daemon/pidfile.h b/project2/daemon/pidfile.h
new file mode 100644
index 0000000..108b0e7
--- /dev/null
+++ b/project2/daemon/pidfile.h
@@ -0,0 +1,16 @@
+#ifndef PIDFILE_H
+#define PIDFILE_H
+
+#include <boost/filesystem/path.hpp>
+
+class PidFile {
+	public:
+		PidFile(const boost::filesystem::path & path);
+		~PidFile();
+
+	private:
+		const boost::filesystem::path Path;
+};
+
+#endif
+
diff --git a/project2/daemon/tempPrivs.cpp b/project2/daemon/tempPrivs.cpp
new file mode 100644
index 0000000..9c5edbd
--- /dev/null
+++ b/project2/daemon/tempPrivs.cpp
@@ -0,0 +1,33 @@
+#include "tempPrivs.h"
+#include "p2daemonAppEngine.h"
+
+TempPrivs::TempPrivs() :
+	originalUid(getuid()),
+	originalGid(getgid())
+{
+	if (DaemonAppEngine::setGroup) {
+		if (setegid(*DaemonAppEngine::setGroup)) {
+			throw std::runtime_error("Failed to set gid");
+		}
+	}
+	if (DaemonAppEngine::setUser) {
+		if (seteuid(*DaemonAppEngine::setUser)) {
+			throw std::runtime_error("Failed to set uid");
+		}
+	}
+}
+
+TempPrivs::~TempPrivs()
+{
+	if (DaemonAppEngine::setUser) {
+		if (seteuid(originalUid)) {
+			throw std::runtime_error("Failed restore uid");
+		}
+	}
+	if (DaemonAppEngine::setGroup) {
+		if (setegid(originalGid)) {
+			throw std::runtime_error("Failed restore gid");
+		}
+	}
+}
+
diff --git a/project2/daemon/tempPrivs.h b/project2/daemon/tempPrivs.h
new file mode 100644
index 0000000..af83fe6
--- /dev/null
+++ b/project2/daemon/tempPrivs.h
@@ -0,0 +1,17 @@
+#ifndef TEMPPRIVS_H
+#define TEMPPRIVS_H
+
+#include <sys/types.h>
+
+class TempPrivs {
+	public:
+		TempPrivs();
+		~TempPrivs();
+
+	private:
+		const uid_t originalUid;
+		const gid_t originalGid;
+};
+
+#endif
+