media-session: add logind seat status support

src/daemon/media-session.d/media-session.conf

@@ -82,6 +82,7 @@ session.modules = {
         #alsa-monitor           # alsa udev detection
         #bluez5                 # bluetooth support
         #restore-stream         # restore stream settings
+        #logind                 # systemd-logind seat support
     ]
     with-audio = [
         metadata
@@ -100,6 +101,7 @@ session.modules = {
     with-pulseaudio = [
         with-audio
         bluez5
+        logind
         restore-stream
         streams-follow-default
     ]

src/examples/media-session/logind.c

@@ -0,0 +1,127 @@
+/* PipeWire
+ *
+ * Copyright © 2021 Pauli Virtanen
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * Monitor systemd-logind events for changes in session/seat status, and keep session
+ * manager up-to-date on whether the current session is active.
+ */
+
+#include "config.h"
+
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <systemd/sd-login.h>
+
+#include <spa/utils/result.h>
+#include "pipewire/pipewire.h"
+
+#include "media-session.h"
+
+#define NAME		"logind"
+
+struct impl {
+	struct sm_media_session *session;
+	struct spa_hook listener;
+	struct pw_context *context;
+
+	sd_login_monitor *monitor;
+	struct spa_source source;
+};
+
+static void update_seat_active(struct impl *impl)
+{
+	char *state;
+	bool active;
+
+	if (sd_uid_get_state(getuid(), &state) < 0)
+		return;
+
+	active = strcmp(state, "active") == 0;
+	free(state);
+
+	sm_media_session_seat_active_changed(impl->session, active);
+}
+
+static void monitor_event(struct spa_source *source)
+{
+	struct impl *impl = source->data;
+	sd_login_monitor_flush(impl->monitor);
+	update_seat_active(impl);
+}
+
+static void session_destroy(void *data)
+{
+	struct impl *impl = data;
+	spa_hook_remove(&impl->listener);
+	if (impl->monitor) {
+		struct pw_loop *main_loop = pw_context_get_main_loop(impl->context);
+		pw_loop_remove_source(main_loop, &impl->source);
+		sd_login_monitor_unref(impl->monitor);
+		impl->monitor = NULL;
+	}
+	free(impl);
+}
+
+static const struct sm_media_session_events session_events = {
+	SM_VERSION_MEDIA_SESSION_EVENTS,
+	.destroy = session_destroy,
+};
+
+int sm_logind_start(struct sm_media_session *session)
+{
+	struct impl *impl;
+	struct pw_loop *main_loop;
+	int res;
+
+	impl = calloc(1, sizeof(struct impl));
+	if (impl == NULL)
+		return -errno;
+
+	impl->session = session;
+	impl->context = session->context;
+
+	if ((res = sd_login_monitor_new(NULL, &impl->monitor)) < 0)
+		goto fail;
+
+	main_loop = pw_context_get_main_loop(impl->context);
+
+	impl->source.data = impl;
+	impl->source.fd = sd_login_monitor_get_fd(impl->monitor);
+	impl->source.func = monitor_event;
+	impl->source.mask = sd_login_monitor_get_events(impl->monitor);
+	impl->source.rmask = 0;
+	pw_loop_add_source(main_loop, &impl->source);
+
+	sm_media_session_add_listener(impl->session, &impl->listener, &session_events, impl);
+
+	update_seat_active(impl);
+
+	return 0;
+
+fail:
+	pw_log_error(NAME ": failed to start systemd logind monitor: %d (%s)", res, spa_strerror(res));
+	free(impl);
+	return res;
+}

src/examples/media-session/media-session.c

@@ -79,6 +79,7 @@
 #define sm_media_session_emit_rescan(s,seq)		sm_media_session_emit(s, rescan, 0, seq)
 #define sm_media_session_emit_shutdown(s)		sm_media_session_emit(s, shutdown, 0)
 #define sm_media_session_emit_destroy(s)		sm_media_session_emit(s, destroy, 0)
+#define sm_media_session_emit_seat_active(s,...)	sm_media_session_emit(s, seat_active, 0, __VA_ARGS__)
 
 int sm_access_flatpak_start(struct sm_media_session *sess);
 int sm_access_portal_start(struct sm_media_session *sess);
@@ -93,6 +94,9 @@ int sm_libcamera_monitor_start(struct sm_media_session *sess);
 int sm_bluez5_monitor_start(struct sm_media_session *sess);
 int sm_alsa_monitor_start(struct sm_media_session *sess);
 int sm_suspend_node_start(struct sm_media_session *sess);
+#ifdef HAVE_SYSTEMD
+int sm_logind_start(struct sm_media_session *sess);
+#endif
 
 int sm_policy_node_start(struct sm_media_session *sess);
 
@@ -157,6 +161,7 @@ struct impl {
 
 	unsigned int scanning:1;
 	unsigned int rescan_pending:1;
+	unsigned int seat_active:1;
 };
 
 struct endpoint_link {
@@ -2034,6 +2039,16 @@ char *sm_media_session_sanitize_description(char *name, int size, char sub, cons
 	return name;
 }
 
+int sm_media_session_seat_active_changed(struct sm_media_session *sess, bool active)
+{
+	struct impl *impl = SPA_CONTAINER_OF(sess, struct impl, this);
+	if (active != impl->seat_active) {
+		impl->seat_active = active;
+		sm_media_session_emit_seat_active(impl, active);
+	}
+	return 0;
+}
+
 static void monitor_core_done(void *data, uint32_t id, int seq)
 {
 	struct impl *impl = data;
@@ -2335,6 +2350,9 @@ static const struct {
 	{ "suspend-node", "suspend inactive nodes", sm_suspend_node_start, NULL },
 	{ "policy-node", "configure and link nodes", sm_policy_node_start, NULL },
 	{ "pulse-bridge", "accept pulseaudio clients", sm_pulse_bridge_start, NULL },
+#ifdef HAVE_SYSTEMD
+	{ "logind", "systemd-logind seat support", sm_logind_start, NULL },
+#endif
 };
 
 static bool is_module_enabled(struct impl *impl, const char *val)
@@ -2363,7 +2381,7 @@ static void show_help(const char *name, struct impl *impl, const char *config_na
 
 int main(int argc, char *argv[])
 {
-	struct impl impl = { 0, };
+	struct impl impl = { .seat_active = true };
 	const struct spa_support *support;
 	const char *str, *config_name = SESSION_CONF;
 	bool do_show_help = false;

src/examples/media-session/media-session.h

@@ -236,6 +236,8 @@ struct sm_media_session_events {
 	void (*rescan) (void *data, int seq);
 	void (*shutdown) (void *data);
 	void (*destroy) (void *data);
+
+	void (*seat_active) (void *data, bool active);
 };
 
 struct sm_media_session {
@@ -311,6 +313,8 @@ char *sm_media_session_sanitize_name(char *name, int size, char sub,
 char *sm_media_session_sanitize_description(char *name, int size, char sub,
 		const char *fmt, ...) SPA_PRINTF_FUNC(4, 5);
 
+int sm_media_session_seat_active_changed(struct sm_media_session *sess, bool active);
+
 #ifdef __cplusplus
 }
 #endif

src/examples/meson.build

@@ -66,6 +66,12 @@ executable('export-spa-device',
 )
 
 if not get_option('media-session').disabled() and alsa_dep.found()
+  sm_logind_src = []
+  sm_logind_dep = []
+  if systemd.found() and systemd_dep.found()
+    sm_logind_src = ['media-session/logind.c']
+    sm_logind_dep = [systemd_dep]
+  endif
   executable('pipewire-media-session',
     'media-session/access-flatpak.c',
     'media-session/access-portal.c',
@@ -90,9 +96,10 @@ if not get_option('media-session').disabled() and alsa_dep.found()
     'media-session/v4l2-endpoint.c',
     'media-session/libcamera-monitor.c',
     'media-session/suspend-node.c',
+    sm_logind_src,
     c_args : [ '-D_GNU_SOURCE' ],
     install: true,
-    dependencies : [dbus_dep, pipewire_dep, alsa_dep, mathlib],
+    dependencies : [dbus_dep, pipewire_dep, alsa_dep, mathlib, sm_logind_dep],
 )
 endif
 

src/pipewire/loop.h

@@ -52,8 +52,8 @@ void
 pw_loop_destroy(struct pw_loop *loop);
 
 #define pw_loop_add_source(l,...)	spa_loop_add_source((l)->loop,__VA_ARGS__)
-#define pw_loop_update_source(l,...)	spa_loop_update_source(__VA_ARGS__)
-#define pw_loop_remove_source(l,...)	spa_loop_remove_source(__VA_ARGS__)
+#define pw_loop_update_source(l,...)	spa_loop_update_source((l)->loop,__VA_ARGS__)
+#define pw_loop_remove_source(l,...)	spa_loop_remove_source((l)->loop,__VA_ARGS__)
 #define pw_loop_invoke(l,...)		spa_loop_invoke((l)->loop,__VA_ARGS__)
 
 #define pw_loop_get_fd(l)		spa_loop_control_get_fd((l)->control)