core: add new "scope" unit type for making a unit of pre-existing processes

"Scope" units are very much like service units, however with the
difference that they are created from pre-existing processes, rather
than processes that systemd itself forks off. This means they are
generated programmatically via the bus API as transient units rather
than from static configuration read from disk. Also, they do not provide
execution-time parameters, as at the time systemd adds the processes to
the scope unit they already exist and the parameters cannot be applied
anymore.

The primary benefit of this new unit type is to create arbitrary cgroups
for worker-processes forked off an existing service.

This commit also adds a a new mode to "systemd-run" to run the specified
processes in a scope rather then a transient service.

1 files changed, 162 insertions, 0 deletions

diff --git a/src/core/dbus-scope.c b/src/core/dbus-scope.c
new file mode 100644
index 0000000000..1497b76761
--- /dev/null
+++ b/src/core/dbus-scope.c
@@ -0,0 +1,162 @@
+/*-*- 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 <errno.h>
+
+#include "dbus-unit.h"
+#include "dbus-common.h"
+#include "dbus-cgroup.h"
+#include "dbus-kill.h"
+#include "selinux-access.h"
+#include "dbus-scope.h"
+
+#define BUS_SCOPE_INTERFACE                                             \
+        " <interface name=\"org.freedesktop.systemd1.Scope\">\n"        \
+        "  <property name=\"TimeoutStopUSec\" type=\"t\" access=\"read\"/>\n" \
+        BUS_KILL_CONTEXT_INTERFACE                                      \
+        BUS_CGROUP_CONTEXT_INTERFACE                                    \
+        "  <property name=\"Result\" type=\"s\" access=\"read\"/>\n"    \
+        " </interface>\n"
+
+#define INTROSPECTION                                                   \
+        DBUS_INTROSPECT_1_0_XML_DOCTYPE_DECL_NODE                       \
+        "<node>\n"                                                      \
+        BUS_UNIT_INTERFACE                                              \
+        BUS_SCOPE_INTERFACE                                             \
+        BUS_PROPERTIES_INTERFACE                                        \
+        BUS_PEER_INTERFACE                                              \
+        BUS_INTROSPECTABLE_INTERFACE                                    \
+        "</node>\n"
+
+#define INTERFACES_LIST                              \
+        BUS_UNIT_INTERFACES_LIST                     \
+        "org.freedesktop.systemd1.Scope\0"
+
+const char bus_scope_interface[] _introspect_("Scope") = BUS_SCOPE_INTERFACE;
+
+static DEFINE_BUS_PROPERTY_APPEND_ENUM(bus_scope_append_scope_result, scope_result, ScopeResult);
+
+static const BusProperty bus_scope_properties[] = {
+        { "TimeoutStopUSec",        bus_property_append_usec,      "t", offsetof(Scope, timeout_stop_usec) },
+        { "Result",                 bus_scope_append_scope_result, "s", offsetof(Scope, result)            },
+        {}
+};
+
+DBusHandlerResult bus_scope_message_handler(Unit *u, DBusConnection *c, DBusMessage *message) {
+        Scope *s = SCOPE(u);
+
+        const BusBoundProperties bps[] = {
+                { "org.freedesktop.systemd1.Unit",  bus_unit_properties,           u },
+                { "org.freedesktop.systemd1.Scope", bus_scope_properties,          s },
+                { "org.freedesktop.systemd1.Scope", bus_cgroup_context_properties, &s->cgroup_context },
+                { "org.freedesktop.systemd1.Scope", bus_kill_context_properties,   &s->kill_context   },
+                {}
+        };
+
+        SELINUX_UNIT_ACCESS_CHECK(u, c, message, "status");
+
+        return bus_default_message_handler(c, message, INTROSPECTION, INTERFACES_LIST, bps);
+}
+
+static int bus_scope_set_transient_properties(
+                Scope *s,
+                const char *name,
+                DBusMessageIter *i,
+                UnitSetPropertiesMode mode,
+                DBusError *error) {
+
+        int r;
+
+        assert(name);
+        assert(s);
+        assert(i);
+
+        if (streq(name, "PIDs")) {
+                DBusMessageIter sub;
+
+                if (dbus_message_iter_get_arg_type(i) != DBUS_TYPE_ARRAY ||
+                    dbus_message_iter_get_element_type(i) != DBUS_TYPE_UINT32)
+                        return -EINVAL;
+
+                r = set_ensure_allocated(&s->pids, trivial_hash_func, trivial_compare_func);
+                if (r < 0)
+                        return r;
+
+                dbus_message_iter_recurse(i, &sub);
+                while (dbus_message_iter_get_arg_type(&sub) == DBUS_TYPE_UINT32) {
+                        uint32_t pid;
+
+                        dbus_message_iter_get_basic(&sub, &pid);
+
+                        if (pid <= 1)
+                                return -EINVAL;
+
+                        r = set_put(s->pids, LONG_TO_PTR(pid));
+                        if (r < 0 && r != -EEXIST)
+                                return r;
+
+                        dbus_message_iter_next(&sub);
+                }
+
+                if (set_size(s->pids) <= 0)
+                        return -EINVAL;
+
+                return 1;
+        }
+
+        return 0;
+}
+
+int bus_scope_set_property(
+                Unit *u,
+                const char *name,
+                DBusMessageIter *i,
+                UnitSetPropertiesMode mode,
+                DBusError *error) {
+
+        Scope *s = SCOPE(u);
+        int r;
+
+        assert(name);
+        assert(u);
+        assert(i);
+
+        r = bus_cgroup_set_property(u, &s->cgroup_context, name, i, mode, error);
+        if (r != 0)
+                return r;
+
+        if (u->load_state == UNIT_STUB) {
+                /* While we are created we still accept PIDs */
+
+                r = bus_scope_set_transient_properties(s, name, i, mode, error);
+                if (r != 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+int bus_scope_commit_properties(Unit *u) {
+        assert(u);
+
+        unit_realize_cgroup(u);
+        return 0;
+}