core: add transient units

Transient units can be created via the bus API. They are configured via
the method call parameters rather than on-disk files. They are subject
to normal GC. Transient units currently may only be created for
services (however, we will extend this), and currently only ExecStart=
and the cgroup parameters can be configured (also to be extended).

Transient units require a unique name, that previously had no
configuration file on disk.

A tool systemd-run is added that makes use of this functionality to run
arbitrary command lines as transient services:

$ systemd-run /bin/ping www.heise.de

Will cause systemd to create a new transient service and run ping in it.

1 files changed, 156 insertions, 0 deletions

diff --git a/src/run/run.c b/src/run/run.c
new file mode 100644
index 0000000000..9f8bda48af
--- /dev/null
+++ b/src/run/run.c
@@ -0,0 +1,156 @@
+/*-*- 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 <stdio.h>
+
+#include "sd-bus.h"
+#include "bus-internal.h"
+#include "bus-message.h"
+#include "strv.h"
+
+static int start_transient_service(
+                sd_bus *bus,
+                const char *name,
+                char **argv,
+                sd_bus_error *error) {
+
+        _cleanup_bus_message_unref_ sd_bus_message *m = NULL, *reply = NULL;
+        char **i;
+        int r;
+
+        r = sd_bus_message_new_method_call(
+                        bus,
+                        "org.freedesktop.systemd1",
+                        "/org/freedesktop/systemd1",
+                        "org.freedesktop.systemd1.Manager",
+                        "StartTransientUnit", &m);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_append(m, "ss", name, "fail");
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_open_container(m, 'a', "(sv)");
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_open_container(m, 'r', "sv");
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_append(m, "s", "ExecStart");
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_open_container(m, 'v', "a(sasb)");
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_open_container(m, 'a', "(sasb)");
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_open_container(m, 'r', "sasb");
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_append(m, "s", argv[0]);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_open_container(m, 'a', "s");
+        if (r < 0)
+                return r;
+
+        STRV_FOREACH(i, argv) {
+                r = sd_bus_message_append(m, "s", *i);
+                if (r < 0)
+                        return r;
+        }
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_append(m, "b", false);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                return r;
+
+        return sd_bus_send_with_reply_and_block(bus, m, 0, error, &reply);
+}
+
+int main(int argc, char* argv[]) {
+        sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_bus_unref_ sd_bus *bus = NULL;
+        _cleanup_free_ char *name = NULL;
+        int r;
+
+        log_parse_environment();
+        log_open();
+
+        if (argc < 2) {
+                log_error("Missing command line.");
+                r = -EINVAL;
+                goto fail;
+        }
+
+        r = sd_bus_open_user(&bus);
+        if (r < 0) {
+                log_error("Failed to create new bus: %s", strerror(-r));
+                goto fail;
+        }
+
+        if (asprintf(&name, "run-%lu.service", (unsigned long) getpid()) < 0) {
+                r = log_oom();
+                goto fail;
+        }
+
+        r = start_transient_service(bus, name, argv + 1, &error);
+        if (r < 0) {
+                log_error("Failed start transient service: %s", error.message);
+                sd_bus_error_free(&error);
+                goto fail;
+        }
+
+fail:
+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}