Add API for calling systemd-machined's DBus API

To register virtual machines and containers with systemd-machined,
and thus have cgroups auto-created, we need to talk over DBus.
This is somewhat tedious code, so introduce a dedicated function
to isolate the DBus call in one place.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

src/util/virsystemd.c

@@ -0,0 +1,148 @@
+/*
+ * virsystemd.c: helpers for using systemd APIs
+ *
+ * Copyright (C) 2013 Red Hat, Inc.
+ *
+ * This library 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.
+ *
+ * This library 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 this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <config.h>
+
+#include "virsystemd.h"
+#include "virdbus.h"
+#include "virstring.h"
+#include "viralloc.h"
+#include "virutil.h"
+
+#define VIR_FROM_THIS VIR_FROM_SYSTEMD
+
+/**
+ * virSystemdCreateMachine:
+ * @name: driver unique name of the machine
+ * @drivername: name of the virt driver
+ * @privileged: whether driver is running privileged or per user
+ * @uuid: globally unique UUID of the machine
+ * @rootdir: root directory of machine filesystem
+ * @pidleader: PID of the leader process
+ * @slice: name of the slice to place the machine in
+ */
+int virSystemdCreateMachine(const char *name,
+                            const char *drivername,
+                            bool privileged,
+                            const unsigned char *uuid,
+                            const char *rootdir,
+                            pid_t pidleader,
+                            bool iscontainer,
+                            const char *partition)
+{
+    int ret = -1;
+    DBusConnection *conn;
+    char *machinename = NULL;
+    char *creatorname = NULL;
+    char *username = NULL;
+    char *slicename = NULL;
+
+    if (!(conn = virDBusGetSystemBus()))
+        return -1;
+
+    if (privileged) {
+        if (virAsprintf(&machinename, "%s-%s", drivername, name) < 0)
+            goto cleanup;
+    } else {
+        if (!(username = virGetUserName(geteuid())))
+            goto cleanup;
+        if (virAsprintf(&machinename, "%s-%s-%s", username, drivername, name) < 0)
+            goto cleanup;
+    }
+
+    if (virAsprintf(&creatorname, "libvirt-%s", drivername) < 0)
+        goto cleanup;
+
+    if (partition) {
+        if (virAsprintf(&slicename, "%s.slice", partition) < 0)
+            goto cleanup;
+    } else {
+        if (VIR_STRDUP(slicename, "") < 0)
+            goto cleanup;
+    }
+
+    /*
+     * The systemd DBus API we're invoking has the
+     * following signature
+     *
+     * CreateMachine(in  s name,
+     *               in  ay id,
+     *               in  s service,
+     *               in  s class,
+     *               in  u leader,
+     *               in  s root_directory,
+     *               in  a(sv) scope_properties,
+     *               out o path);
+     *
+     * @name a host unique name for the machine. shows up
+     * in 'ps' listing & similar
+     *
+     * @id: a UUID of the machine, ideally matching /etc/machine-id
+     * for containers
+     *
+     * @service: identifier of the client ie "libvirt-lxc"
+     *
+     * @class: either the string "container" or "vm" depending
+     * on the type of machine
+     *
+     * @leader: main PID of the machine, either the host emulator
+     * process, or the 'init' PID of the container
+     *
+     * @root_directory: the root directory of the container, if
+     * this is known & visible in the host filesystem, or empty string
+     *
+     * @scope_properties:an array (not a dict!) of properties that are
+     * passed on to PID 1 when creating a scope unit for your machine.
+     * Will allow initial settings for the cgroup & similar.
+     *
+     * @path: a bus path returned for the machine object created, to
+     * allow further API calls to be made against the object.
+     */
+
+    if (virDBusCallMethod(conn,
+                          NULL,
+                          "org.freedesktop.machine1",
+                          "/org/freedesktop/machine1",
+                          "org.freedesktop.machine1.Manager",
+                          "CreateMachine",
+                          "sayssusa(sv)",
+                          machinename,
+                          16,
+                          uuid[0], uuid[1], uuid[2], uuid[3],
+                          uuid[4], uuid[5], uuid[6], uuid[7],
+                          uuid[8], uuid[9], uuid[10], uuid[11],
+                          uuid[12], uuid[13], uuid[14], uuid[15],
+                          creatorname,
+                          iscontainer ? "container" : "vm",
+                          (unsigned int)pidleader,
+                          rootdir ? rootdir : "",
+                          1, "Slice", "s",
+                          slicename) < 0)
+        goto cleanup;
+
+    ret = 0;
+
+cleanup:
+    VIR_FREE(username);
+    VIR_FREE(creatorname);
+    VIR_FREE(machinename);
+    return ret;
+}