shutdown: issue a sync() as soon as shutdown.target is queued

1 files changed, 65 insertions, 0 deletions

diff --git a/src/core/sync.c b/src/core/sync.c
new file mode 100644
index 0000000000..7e74b63071
--- /dev/null
+++ b/src/core/sync.c
@@ -0,0 +1,65 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2013 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <pthread.h>
+#include <unistd.h>
+
+#include "sync.h"
+
+static void *sync_thread(void *p) {
+        sync();
+        return NULL;
+}
+
+int asynchronous_sync(void) {
+        pthread_attr_t a;
+        pthread_t t;
+        int r;
+
+        /* It kinda sucks that we have to resort to threads to
+         * implement an asynchronous sync(), but well, such is
+         * life.
+         *
+         * Note that issuing this command right before exiting a
+         * process will cause the process to wait for the sync() to
+         * complete. This function hence is nicely asynchronous really
+         * only in long running processes. */
+
+        r = pthread_attr_init(&a);
+        if (r != 0)
+                return -r;
+
+        r = pthread_attr_setdetachstate(&a, PTHREAD_CREATE_DETACHED);
+        if (r != 0) {
+                r = -r;
+                goto finish;
+        }
+
+        r = pthread_create(&t, &a, sync_thread, NULL);
+        if (r != 0) {
+                r = -r;
+                goto finish;
+        }
+
+finish:
+        pthread_attr_destroy(&a);
+        return r;
+}