uuidd: implement --socket-activation option

Implement --socket-activation option, which is supposed to be used
with systemd (or equivalent init system) socket activation mechanism.
With this option, the UUID daemon does not create the socket on its own,
but instead expect the connection fd to be provided by the calling
process.

This option is only available if util-linux is configured with
--enable-socket-activation option. With this configure
option, the uuidd is compiled with sd-daemon.c.

Signed-off-by: Petr Uzel <petr.uzel@suse.cz>

1 files changed, 90 insertions, 44 deletions

diff --git a/misc-utils/uuidd.c b/misc-utils/uuidd.c
index 0ea6288d1..c6ec208c1 100644
--- a/misc-utils/uuidd.c
+++ b/misc-utils/uuidd.c
@@ -35,8 +35,12 @@ extern int optind;
 #include "uuidd.h"
 #include "writeall.h"
 #include "c.h"
-
 #include "closestream.h"
+
+#ifdef USE_SOCKET_ACTIVATION
+#include "sd-daemon.h"
+#endif
+
 #include "nls.h"
 
 #ifdef __GNUC__
@@ -58,19 +62,20 @@ static void __attribute__ ((__noreturn__)) usage(FILE * out)
 	      _(" %s [options]\n"), program_invocation_short_name);
 
 	fputs(_("\nOptions:\n"), out);
-	fputs(_(" -p, --pid <path>    path to pid file\n"
-		" -s, --socket <path> path to socket\n"
-		" -T, --timeout <sec> specify inactivity timeout\n"
-		" -k, --kill          kill running daemon\n"
-		" -r, --random        test random-based generation\n"
-		" -t, --time          test time-based generation\n"
-		" -n, --uuids <num>   request number of uuids\n"
-		" -P, --no-pid        do not create pid file\n"
-		" -F, --no-fork       do not daemonize using double-fork\n"
-		" -d, --debug         run in debugging mode\n"
-		" -q, --quiet         turn on quiet mode\n"
-		" -V, --version       output version information and exit\n"
-		" -h, --help          display this help and exit\n\n"), out);
+	fputs(_(" -p, --pid <path>        path to pid file\n"
+		" -s, --socket <path>     path to socket\n"
+		" -T, --timeout <sec>     specify inactivity timeout\n"
+		" -k, --kill              kill running daemon\n"
+		" -r, --random            test random-based generation\n"
+		" -t, --time              test time-based generation\n"
+		" -n, --uuids <num>       request number of uuids\n"
+		" -P, --no-pid            do not create pid file\n"
+		" -F, --no-fork           do not daemonize using double-fork\n"
+		" -S, --socket-activation do not create listening socket\n"
+		" -d, --debug             run in debugging mode\n"
+		" -q, --quiet             turn on quiet mode\n"
+		" -V, --version           output version information and exit\n"
+		" -h, --help              display this help and exit\n\n"), out);
 
 	exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
 }
@@ -302,7 +307,8 @@ static int create_socket(const char *socket_path, int will_fork, int quiet)
 }
 
 static void server_loop(const char *socket_path, const char *pidfile_path,
-			int debug, int timeout, int quiet, int no_fork)
+			int debug, int timeout, int quiet, int no_fork,
+			int no_sock)
 {
 	struct sockaddr_un	from_addr;
 	socklen_t		fromlen;
@@ -310,48 +316,68 @@ static void server_loop(const char *socket_path, const char *pidfile_path,
 	uuid_t			uu;
 	char			reply_buf[1024], *cp;
 	char			op, str[UUID_STR_LEN];
-	int			i, s, ns, len, num;
+	int			i, ns, len, num;
+	int			s = 0;
 	int			fd_pidfile = -1;
 	int			ret;
 
-	signal(SIGALRM, terminate_intr);
-	alarm(30);
+#ifdef USE_SOCKET_ACTIVATION
+	if (!no_sock)	/* no_sock implies no_fork and no_pid */
+#endif
+	{
 
-	if (pidfile_path)
-		fd_pidfile = create_pidfile(pidfile_path, quiet);
+		signal(SIGALRM, terminate_intr);
+		alarm(30);
+		if (pidfile_path)
+			fd_pidfile = create_pidfile(pidfile_path, quiet);
 
-	ret = call_daemon(socket_path, UUIDD_OP_GETPID, reply_buf, sizeof(reply_buf), 0, NULL);
-	if (ret > 0) {
-		if (!quiet)
-			printf(_("uuidd daemon already running at pid %s\n"),
-			       reply_buf);
-		exit(EXIT_FAILURE);
-	}
-	alarm(0);
+		ret = call_daemon(socket_path, UUIDD_OP_GETPID, reply_buf,
+				  sizeof(reply_buf), 0, NULL);
+		if (ret > 0) {
+			if (!quiet)
+				printf(_("uuidd daemon already running at pid %s\n"),
+				       reply_buf);
+			exit(EXIT_FAILURE);
+		}
+		alarm(0);
+
+		s = create_socket(socket_path, (!debug || !no_fork), quiet);
+		if (listen(s, SOMAXCONN) < 0) {
+			if (!quiet)
+				fprintf(stderr, _("Couldn't listen on unix "
+						  "socket %s: %m\n"), socket_path);
+			exit(EXIT_FAILURE);
+		}
+
+		if (!debug && !no_fork)
+			create_daemon();
+
+		if (pidfile_path) {
+			sprintf(reply_buf, "%8d\n", getpid());
+			ignore_result( ftruncate(fd_pidfile, 0) );
+			write_all(fd_pidfile, reply_buf, strlen(reply_buf));
+			if (fd_pidfile > 1)
+				close(fd_pidfile); /* Unlock the pid file */
+		}
 
-	s = create_socket(socket_path, (!debug || !no_fork), quiet);
-	if (listen(s, SOMAXCONN) < 0) {
-		if (!quiet)
-			fprintf(stderr, _("Couldn't listen on unix "
-					  "socket %s: %m\n"), socket_path);
-		exit(EXIT_FAILURE);
 	}
 
-	if (!debug && !no_fork)
-		create_daemon();
 	signal(SIGHUP, terminate_intr);
 	signal(SIGINT, terminate_intr);
 	signal(SIGTERM, terminate_intr);
 	signal(SIGALRM, terminate_intr);
 	signal(SIGPIPE, SIG_IGN);
 
-	if (pidfile_path) {
-		sprintf(reply_buf, "%8d\n", getpid());
-		ignore_result( ftruncate(fd_pidfile, 0) );
-		write_all(fd_pidfile, reply_buf, strlen(reply_buf));
-		if (fd_pidfile > 1)
-			close(fd_pidfile); /* Unlock the pid file */
+#ifdef USE_SOCKET_ACTIVATION
+	if (no_sock) {
+		if (sd_listen_fds(0) != 1) {
+			fprintf(stderr, _("No or too many file descriptors received.\n"));
+			exit(EXIT_FAILURE);
+		}
+
+		s = SD_LISTEN_FDS_START + 0;
 	}
+#endif
 
 	while (1) {
 		fromlen = sizeof(from_addr);
@@ -482,6 +508,7 @@ int main(int argc, char **argv)
 	int		debug = 0, do_type = 0, do_kill = 0, num = 0;
 	int		timeout = 0, quiet = 0, drop_privs = 0;
 	int		no_pid = 0, no_fork = 0;
+	int		no_sock = 0, s_flag = 0;
 
 	static const struct option longopts[] = {
 		{"pid", required_argument, NULL, 'p'},
@@ -493,6 +520,7 @@ int main(int argc, char **argv)
 		{"uuids", required_argument, NULL, 'n'},
 		{"no-pid", no_argument, NULL, 'P'},
 		{"no-fork", no_argument, NULL, 'F'},
+		{"socket-activation", no_argument, NULL, 'S'},
 		{"debug", no_argument, NULL, 'd'},
 		{"quiet", no_argument, NULL, 'q'},
 		{"version", no_argument, NULL, 'V'},
@@ -506,7 +534,7 @@ int main(int argc, char **argv)
 	atexit(close_stdout);
 
 	while ((c =
-		getopt_long(argc, argv, "p:s:T:krtn:PFdqVh", longopts,
+		getopt_long(argc, argv, "p:s:T:krtn:PFSdqVh", longopts,
 			    NULL)) != -1) {
 		switch (c) {
 		case 'd':
@@ -536,6 +564,18 @@ int main(int argc, char **argv)
 			no_fork = 1;
 			drop_privs = 1;
 			break;
+		case 'S':
+#ifdef USE_SOCKET_ACTIVATION
+			no_sock = 1;
+			drop_privs = 1;
+			no_fork = 1;
+			no_pid = 1;
+#else
+			fprintf(stderr,
+				_("uuidd has been built without support for socket activation.\n"));
+			return EXIT_FAILURE;
+#endif
+			break;
 		case 'q':
 			quiet++;
 			break;
@@ -545,6 +585,7 @@ int main(int argc, char **argv)
 			break;
 		case 's':
 			socket_path = optarg;
+			s_flag = 1;
 			drop_privs = 1;
 			break;
 		case 't':
@@ -579,6 +620,10 @@ int main(int argc, char **argv)
 	else if (pidfile_path_param)
 		pidfile_path = pidfile_path_param;
 
+	/* custom socket path and socket-activation make no sense */
+	if (s_flag && no_sock && !quiet)
+		fprintf(stderr, _("Both --socket-activation and --socket specified. "
+				  "Ignoring --socket\n"));
 
 	uid = getuid();
 	if (uid && drop_privs) {
@@ -661,6 +706,7 @@ int main(int argc, char **argv)
 		return EXIT_SUCCESS;
 	}
 
-	server_loop(socket_path, pidfile_path, debug, timeout, quiet, no_fork);
+	server_loop(socket_path, pidfile_path, debug, timeout, quiet, no_fork,
+		    no_sock);
 	return EXIT_SUCCESS;
 }