user-sessions: add minimal utility to kill user sessions that shall be called before destroying services on shutdown

.gitignore

@@ -1,3 +1,4 @@
+systemd-user-sessions
 systemd-shutdown
 systemd-tmpfiles
 systemd-readahead-collect

Makefile.am

@@ -107,7 +107,8 @@ rootlibexec_PROGRAMS = \
 	systemd-reply-password \
 	systemd-readahead-collect \
 	systemd-readahead-replay \
-	systemd-tmpfiles
+	systemd-tmpfiles \
+	systemd-user-sessions
 
 noinst_PROGRAMS = \
 	test-engine \
@@ -671,6 +672,16 @@ systemd_tmpfiles_SOURCES = \
 systemd_tmpfiles_CFLAGS = \
 	$(AM_CFLAGS)
 
+systemd_user_sessions_LDADD = \
+	libsystemd-basic.la
+
+systemd_user_sessions_SOURCES = \
+	src/user-sessions.c \
+	src/cgroup-util.c
+
+systemd_user_sessions_CFLAGS = \
+	$(AM_CFLAGS)
+
 systemd_modules_load_LDADD = \
 	libsystemd-basic.la
 

src/user-sessions.c

@@ -0,0 +1,74 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "log.h"
+#include "util.h"
+#include "cgroup-util.h"
+
+int main(int argc, char*argv[]) {
+        int ret = EXIT_FAILURE;
+
+        if (argc != 2) {
+                log_error("This program requires one argument.");
+                return EXIT_FAILURE;
+        }
+
+        log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
+        log_parse_environment();
+        log_open();
+
+        if (streq(argv[1], "start")) {
+
+                if (unlink("/var/run/nologin") < 0 ||
+                    unlink("/etc/nologin") < 0) {
+
+                        if (errno != ENOENT) {
+                                log_error("Failed to remove nologin files: %m");
+                                goto finish;
+                        }
+                }
+
+        } else if (streq(argv[1], "stop")) {
+                int r, q;
+
+                if ((r = write_one_line_file("/var/run/nologin", "System is going down.")) < 0)
+                        log_error("Failed to create /var/run/nologin: %s", strerror(-r));
+
+                if ((q = cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, "/user", true)) < 0)
+                        log_error("Failed to kill sessions: %s", strerror(-q));
+
+                if (r < 0 || q < 0)
+                        goto finish;
+
+        } else {
+                log_error("Unknown verb %s.", argv[1]);
+                goto finish;
+        }
+
+        ret = EXIT_SUCCESS;
+
+finish:
+        return ret;
+}