WHATS_NEW_DM                |    1 +

 daemons/dmeventd/dmeventd.c |   95 +++++++++++++++++++++++++++++++++++++++++--

 2 files changed, 92 insertions(+), 4 deletions(-)

diff --git a/WHATS_NEW_DM b/WHATS_NEW_DM

index 868a469..d09a50c 100644

--- a/WHATS_NEW_DM

+++ b/WHATS_NEW_DM

@@ -1,5 +1,6 @@

 Version 1.02.66 -

 ===============================

+  Add support for systemd file descriptor handover to dmeventd.

   Add support for new oom killer adjustment interface (oom_score_adj).

   Add systemd unit files for dmeventd.

diff --git a/daemons/dmeventd/dmeventd.c b/daemons/dmeventd/dmeventd.c

index a6956cb..ec514ee 100644

--- a/daemons/dmeventd/dmeventd.c

+++ b/daemons/dmeventd/dmeventd.c

@@ -55,6 +55,13 @@

 /* New interface */

 #  define OOM_SCORE_ADJ_MIN (-1000)

+/* Systemd on-demand activation support */

+#  define SD_LISTEN_PID_ENV_VAR_NAME "LISTEN_PID"

+#  define SD_LISTEN_FDS_ENV_VAR_NAME "LISTEN_FDS"

+#  define SD_LISTEN_FDS_START 3

+#  define SD_FD_FIFO_SERVER SD_LISTEN_FDS_START

+#  define SD_FD_FIFO_CLIENT (SD_LISTEN_FDS_START + 1)

+

 #endif

 /* FIXME We use syslog for now, because multilog is not yet implemented */

@@ -104,6 +111,7 @@ static pthread_mutex_t _global_mutex;

 #define THREAD_STACK_SIZE (300*1024)

 int dmeventd_debug = 0;

+static int _systemd_activation = 0;

 static int _foreground = 0;

 static int _restart = 0;

 static char **_initial_registrations = 0;

@@ -1710,8 +1718,13 @@ static void _daemonize(void)

 	else

 		fd = rlim.rlim_cur;

-	for (--fd; fd >= 0; fd--)

+	for (--fd; fd >= 0; fd--) {

+		/* Do not close fds preloaded by systemd! */

+		if (_systemd_activation &&

+		    (fd == SD_FD_FIFO_SERVER || fd == SD_FD_FIFO_CLIENT))

+			continue;

 		close(fd);

+	}

 	if ((open("/dev/null", O_RDONLY) < 0) ||

 	    (open("/dev/null", O_WRONLY) < 0) ||

@@ -1780,6 +1793,76 @@ static void restart(void)

 	fini_fifos(&fifos);

 }

+static int _handle_preloaded_fifo(int fd, const char *path)

+{

+	struct stat st_fd, st_path;

+	int flags;

+

+	if ((flags = fcntl(fd, F_GETFD)) < 0)

+		return 0;

+

+	if (flags & FD_CLOEXEC)

+		return 0;

+

+	if (fstat(fd, &st_fd) < 0 || !S_ISFIFO(st_fd.st_mode))

+		return 0;

+

+	if (stat(path, &st_path) < 0 ||

+	    st_path.st_dev != st_fd.st_dev ||

+	    st_path.st_ino != st_fd.st_ino)

+		return 0;

+

+	if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) < 0)

+		return 0;

+

+	return 1;

+}

+

+static int _systemd_handover(struct dm_event_fifos *fifos)

+{

+	const char *e;

+	char *p;

+	unsigned long env_pid, env_listen_fds;

+	int r = 0;

+

+	memset(fifos, 0, sizeof(*fifos));

+

+	/* LISTEN_PID must be equal to our PID! */

+	if (!(e = getenv(SD_LISTEN_PID_ENV_VAR_NAME)))

+		goto out;

+

+	errno = 0;

+	env_pid = strtoul(e, &p, 10);

+	if (errno || !p || *p || env_pid <= 0 ||

+	    getpid() != (pid_t) env_pid)

+		goto out;

+

+	/* LISTEN_FDS must be 2 and the fds must be FIFOSs! */

+	if (!(e = getenv(SD_LISTEN_FDS_ENV_VAR_NAME)))

+		goto out;

+

+	errno = 0;

+	env_listen_fds = strtoul(e, &p, 10);

+	if (errno || !p || *p || env_listen_fds != 2)

+		goto out;

+

+	/* Check and handle the FIFOs passed in */

+	r = (_handle_preloaded_fifo(SD_FD_FIFO_SERVER, DM_EVENT_FIFO_SERVER) &&

+	     _handle_preloaded_fifo(SD_FD_FIFO_CLIENT, DM_EVENT_FIFO_CLIENT));

+

+	if (r) {

+		fifos->server = SD_FD_FIFO_SERVER;

+		fifos->server_path = DM_EVENT_FIFO_SERVER;

+		fifos->client = SD_FD_FIFO_CLIENT;

+		fifos->client_path = DM_EVENT_FIFO_CLIENT;

+	}

+

+out:

+	unsetenv(SD_LISTEN_PID_ENV_VAR_NAME);

+	unsetenv(SD_LISTEN_FDS_ENV_VAR_NAME);

+	return r;

+}

+

 static void usage(char *prog, FILE *file)

 {

 	fprintf(file, "Usage:\n"

@@ -1834,6 +1917,8 @@ int main(int argc, char *argv[])

 	if (_restart)

 		restart();

+	_systemd_activation = _systemd_handover(&fifos);

+

 	if (!_foreground)

 		_daemonize();

@@ -1852,7 +1937,8 @@ int main(int argc, char *argv[])

 	signal(SIGQUIT, &_exit_handler);

 #ifdef linux

-	if (!_protect_against_oom_killer())

+	/* Systemd has adjusted oom killer for us already */

+	if (!_systemd_activation && !_protect_against_oom_killer())

 		syslog(LOG_ERR, "Failed to protect against OOM killer");

 #endif

@@ -1863,11 +1949,12 @@ int main(int argc, char *argv[])

 	//multilog_init_verbose(std_syslog, _LOG_DEBUG);

 	//multilog_async(1);

-	_init_fifos(&fifos);

+	if (!_systemd_activation)

+		_init_fifos(&fifos);

 	pthread_mutex_init(&_global_mutex, NULL);

-	if (_open_fifos(&fifos))

+	if (!_systemd_activation && _open_fifos(&fifos))

 		exit(EXIT_FIFO_FAILURE);

 	/* Signal parent, letting them know we are ready to go. */