[gnome-desktop/benzea/systemd-start-scope] systemd: Add utility function to start a transient systemd scope
- From: Benjamin Berg <bberg src gnome org>
- To: commits-list gnome org
- Cc:
- Subject: [gnome-desktop/benzea/systemd-start-scope] systemd: Add utility function to start a transient systemd scope
- Date: Sat, 30 Nov 2019 16:00:04 +0000 (UTC)
commit 849c6533af47efc5c709c6b03ce400961ba2d50d
Author: Benjamin Berg <bberg redhat com>
Date: Sat Nov 30 16:49:10 2019 +0100
systemd: Add utility function to start a transient systemd scope
In a systemd world, it is often a good idea to move launched
applications outside of the own unit into one of their own. This helper
allows to do so in a safe and consistent way.
config.h.meson | 5 +-
libgnome-desktop/gnome-systemd.c | 184 +++++++++++++++++++++++++++++++++++++++
libgnome-desktop/gnome-systemd.h | 30 +++++++
libgnome-desktop/meson.build | 3 +
meson.build | 3 +
meson_options.txt | 4 +
6 files changed, 228 insertions(+), 1 deletion(-)
---
diff --git a/config.h.meson b/config.h.meson
index 2c72485a..7a8d8d96 100644
--- a/config.h.meson
+++ b/config.h.meson
@@ -12,10 +12,13 @@
/* we have the timerfd_create(2) system call */
#mesondefine HAVE_TIMERFD
-#
+
/* Define to 1 if you have the `openat' function. */
#mesondefine HAVE_OPENAT
+/* define if libsystemd is available */
+#mesondefine HAVE_SYSTEMD
+
/* define if udev is available */
#mesondefine HAVE_UDEV
diff --git a/libgnome-desktop/gnome-systemd.c b/libgnome-desktop/gnome-systemd.c
new file mode 100644
index 00000000..1cafb9c8
--- /dev/null
+++ b/libgnome-desktop/gnome-systemd.c
@@ -0,0 +1,184 @@
+/* gnome-systemd.c
+ *
+ * Copyright 2019 Benjamin Berg <bberg redhat com>
+ *
+ * This file 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 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This file 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 program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: LGPL-3.0-or-later
+ */
+
+#include "config.h"
+#include "gnome-systemd.h"
+
+#ifdef HAVE_SYSTEMD
+#include <errno.h>
+#include <systemd/sd-login.h>
+#endif
+
+#ifdef HAVE_SYSTEMD
+static void
+on_systemd_call_cb (GObject *source,
+ GAsyncResult *res,
+ gpointer user_data)
+{
+ g_autoptr (GVariant) reply = NULL;
+ g_autoptr (GError) error = NULL;
+ const gchar *command = user_data;
+
+ reply = g_dbus_connection_call_finish (G_DBUS_CONNECTION (source),
+ res, &error);
+ if (error && !g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+ g_warning ("Could not issue '%s' systemd call", command);
+}
+#endif
+
+/**
+ * gnome_start_systemd_scope:
+ * @name: Name for the application
+ * @pid: The PID of the application
+ * @description: (nullable): A description to use for the unit, or %NULL
+ * @connection: (nullable): An #GDBusConnection to the session bus, or %NULL to use a new connection
+ * @error: #GError
+ *
+ * If the current process is running inside a user systemd instance, then move
+ * the launched PID into a transient scope. The given @name will be used to
+ * create a unit name. It should be the application ID for desktop files or
+ * the executable in all other cases.
+ *
+ * It is advisable to use this function every time where the started application
+ * can be considered reasonably independent of the launching application. Placing
+ * it in a scope creates proper separation between the programs rather than being
+ * considered a single entity by systemd.
+ *
+ * If given, the existing @connection is used for the sessions bus otherwise
+ * g_bus_get_sync() is called.
+ *
+ * It is always safe to call this function. Note that a successful return code
+ * does not imply that a unit has been created. It solely means that no error
+ * condition was hit sending the request.
+ *
+ * Returns: %TRUE on success, %FALSE
+ */
+gboolean
+gnome_start_systemd_scope (const char *name,
+ gint32 pid,
+ const char *description,
+ GDBusConnection *connection,
+ GError **error)
+{
+#ifdef HAVE_SYSTEMD
+ GVariantBuilder builder;
+ const char *valid_chars =
+ "-._1234567890"
+ "abcdefghijklmnopqrstuvwxyz"
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+ g_autofree char *description_free = NULL;
+ g_autofree char *mangled_name = NULL;
+ g_autofree char *unit_name = NULL;
+ g_autofree char *own_unit = NULL;
+ gint res;
+ g_autoptr (GDBusConnection) connection_unref = NULL;
+
+ /* We cannot do anything if this process is not managed by the
+ * systemd user instance. */
+ res = sd_pid_get_user_unit (getpid (), &own_unit);
+ if (res == -ENODATA)
+ {
+ g_debug ("Not systemd managed, will not move PID %d into transient scope\n", pid);
+ return TRUE;
+ }
+ if (res < 0)
+ {
+ g_propagate_error (error,
+ g_error_new (G_IO_ERROR,
+ g_io_error_from_errno (-res),
+ "Error fetching user unit for own pid: %d", -res));
+
+ return FALSE;
+ }
+
+ if (connection == NULL)
+ {
+ connection = g_bus_get_sync (G_BUS_TYPE_SESSION, NULL, error);
+ connection_unref = connection;
+
+ if (connection == NULL)
+ return FALSE;
+ }
+
+ g_debug ("Trying to create transient scope for PID %d", pid);
+
+ /* Create a nice and (mangled) name to embed into the unit */
+ if (name == NULL)
+ name = "anonymous";
+ if (name[0] == '/')
+ name++;
+
+ mangled_name = g_str_to_ascii (name, "C");
+ g_strdelimit (mangled_name, "/", '-');
+ g_strcanon (mangled_name, valid_chars, '_');
+
+ if (description == NULL)
+ {
+ const char *app_name = g_get_application_name();
+
+ if (app_name)
+ description_free = g_strdup_printf ("Application launched by %s",
+ app_name);
+ description = description_free;
+ }
+
+ /* This needs to be unique, hopefully the pid will be enough. */
+ unit_name = g_strdup_printf ("gnome-launched-%s-%d.scope", mangled_name, pid);
+
+
+ g_variant_builder_init (&builder, G_VARIANT_TYPE ("(ssa(sv)a(sa(sv)))"));
+ g_variant_builder_add (&builder, "s", unit_name);
+ g_variant_builder_add (&builder, "s", "fail");
+
+ /* Note that gnome-session ships a drop-in to control further defaults. */
+ g_variant_builder_open (&builder, G_VARIANT_TYPE ("a(sv)"));
+ g_variant_builder_add (&builder,
+ "(sv)",
+ "Description",
+ g_variant_new_string (description));
+ g_variant_builder_add (&builder,
+ "(sv)",
+ "PIDs",
+ g_variant_new_fixed_array (G_VARIANT_TYPE_UINT32, &pid, 1, 4));
+
+ g_variant_builder_close (&builder);
+
+ g_variant_builder_open (&builder, G_VARIANT_TYPE ("a(sa(sv))"));
+ g_variant_builder_close (&builder);
+
+ g_dbus_connection_call (connection,
+ "org.freedesktop.systemd1",
+ "/org/freedesktop/systemd1",
+ "org.freedesktop.systemd1.Manager",
+ "StartTransientUnit",
+ g_variant_builder_end (&builder),
+ G_VARIANT_TYPE ("(o)"),
+ G_DBUS_CALL_FLAGS_NO_AUTO_START,
+ 1000,
+ NULL,
+ on_systemd_call_cb,
+ (gpointer) "StartTransientUnit");
+#else
+ g_debug ("Not creating transient scope for PID %d. Systemd support not compiled in.", pid);
+#endif
+
+ return TRUE;
+}
+
diff --git a/libgnome-desktop/gnome-systemd.h b/libgnome-desktop/gnome-systemd.h
new file mode 100644
index 00000000..fa2ae6da
--- /dev/null
+++ b/libgnome-desktop/gnome-systemd.h
@@ -0,0 +1,30 @@
+/* gnome-systemd.h
+ *
+ * Copyright 2019 Benjamin Berg <bberg redhat com>
+ *
+ * This file 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 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This file 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 program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: LGPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <gio/gio.h>
+
+gboolean gnome_start_systemd_scope (const char *name,
+ gint32 pid,
+ const char *description,
+ GDBusConnection *connection,
+ GError **error);
+
diff --git a/libgnome-desktop/meson.build b/libgnome-desktop/meson.build
index 8503215f..01d10b7e 100644
--- a/libgnome-desktop/meson.build
+++ b/libgnome-desktop/meson.build
@@ -17,6 +17,7 @@ introspection_sources = [
'gnome-rr.c',
'gnome-rr-config.c',
'gnome-rr-output-info.c',
+ 'gnome-systemd.c',
'gnome-pnp-ids.c',
'gnome-wall-clock.c',
'gnome-xkb-info.c',
@@ -57,6 +58,7 @@ libgnome_desktop_headers = [
'gnome-desktop-thumbnail.h',
'gnome-rr.h',
'gnome-rr-config.h',
+ 'gnome-systemd.h',
'gnome-pnp-ids.h',
'gnome-wall-clock.h',
'gnome-xkb-info.h',
@@ -75,6 +77,7 @@ gnome_desktop_deps = [
glib_dep,
gio_dep,
gio_unix_dep,
+ libsystemd_dep,
schemas_dep,
xkb_config_dep,
iso_codes_dep,
diff --git a/meson.build b/meson.build
index 6876c2c3..360d6600 100644
--- a/meson.build
+++ b/meson.build
@@ -50,6 +50,8 @@ xkb_config_dep = dependency('xkeyboard-config')
iso_codes_dep = dependency('iso-codes')
x_dep = dependency('x11')
+libsystemd_dep = dependency('libsystemd', required: get_option('systemd'))
+
udev_dep = dependency('libudev', required: get_option('udev'))
# Check for bubblewrap compatible platform
@@ -85,6 +87,7 @@ conf.set('ENABLE_SECCOMP', seccomp_dep.found())
conf.set('HAVE_BWRAP', seccomp_dep.found())
conf.set('_GNU_SOURCE', seccomp_dep.found())
+conf.set('HAVE_SYSTEMD', libsystemd_dep.found())
conf.set('HAVE_UDEV', udev_dep.found())
conf.set('HAVE_TIMERFD', cc.has_function('timerfd_create'))
diff --git a/meson_options.txt b/meson_options.txt
index e3402a11..c0fea3f8 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -21,6 +21,10 @@ option('udev',
type: 'feature', description: 'Udev support'
)
+option('systemd',
+ type: 'feature', description: 'Systemd integration support'
+)
+
option('gtk_doc',
type: 'boolean', value: false, description: 'Build API reference'
)
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