daemon.conf: Add boolean rescue_streams parameter

Since merge requests

https://gitlab.freedesktop.org/pulseaudio/pulseaudio/merge_requests/209 and
https://gitlab.freedesktop.org/pulseaudio/pulseaudio/merge_requests/216

the rescuing of streams could no longer be disabled. This patch adds a boolean
parameter rescue-streams to daemon.conf which allows to disable rescuing.

The parameter defaults to true (rescuing enabled).

man/pulse-daemon.conf.5.xml.in

@@ -255,6 +255,15 @@ License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
       to <opt>no</opt>.</p>
     </option>
 
+    <option>
+      <p><opt>rescue-streams=</opt> Enable rescuing of streams if the
+      used sink or source becomes unavailable. Takes a boolean argument.
+      If set to <opt>yes</opt>, pulseaudio will try to move the streams
+      from a sink or source that becomes unavailable to the default sink
+      or source. If set to <opt>no</opt>, streams will be killed if the
+      corresponding sink or source disappears. Defaults to <opt>yes</opt>.</p>
+    </option>
+
   </section>
 
   <section name="Scheduling">

src/daemon/daemon-conf.c

@@ -69,6 +69,7 @@ static const pa_daemon_conf default_conf = {
     .disallow_module_loading = false,
     .disallow_exit = false,
     .flat_volumes = false,
+    .rescue_streams = true,
     .exit_idle_time = 20,
     .scache_idle_time = 20,
     .script_commands = NULL,
@@ -580,6 +581,7 @@ int pa_daemon_conf_load(pa_daemon_conf *c, const char *filename) {
         { "enable-shm",                 pa_config_parse_not_bool, &c->disable_shm, NULL },
         { "enable-memfd",               pa_config_parse_not_bool, &c->disable_memfd, NULL },
         { "flat-volumes",               pa_config_parse_bool,     &c->flat_volumes, NULL },
+        { "rescue-streams",             pa_config_parse_bool,     &c->rescue_streams, NULL },
         { "lock-memory",                pa_config_parse_bool,     &c->lock_memory, NULL },
         { "enable-deferred-volume",     pa_config_parse_bool,     &c->deferred_volume, NULL },
         { "exit-idle-time",             pa_config_parse_int,      &c->exit_idle_time, NULL },
@@ -794,6 +796,7 @@ char *pa_daemon_conf_dump(pa_daemon_conf *c) {
     pa_strbuf_printf(s, "cpu-limit = %s\n", pa_yes_no(!c->no_cpu_limit));
     pa_strbuf_printf(s, "enable-shm = %s\n", pa_yes_no(!c->disable_shm));
     pa_strbuf_printf(s, "flat-volumes = %s\n", pa_yes_no(c->flat_volumes));
+    pa_strbuf_printf(s, "rescue-streams = %s\n", pa_yes_no(c->rescue_streams));
     pa_strbuf_printf(s, "lock-memory = %s\n", pa_yes_no(c->lock_memory));
     pa_strbuf_printf(s, "exit-idle-time = %i\n", c->exit_idle_time);
     pa_strbuf_printf(s, "scache-idle-time = %i\n", c->scache_idle_time);

src/daemon/daemon-conf.h

@@ -77,6 +77,7 @@ typedef struct pa_daemon_conf {
         log_meta,
         log_time,
         flat_volumes,
+        rescue_streams,
         lock_memory,
         deferred_volume;
     pa_server_type_t local_server_type;

src/daemon/daemon.conf.in

@@ -63,6 +63,8 @@ ifelse(@HAVE_DBUS@, 1, [dnl
 
 ; flat-volumes = no
 
+; rescue-streams = yes
+
 ifelse(@HAVE_SYS_RESOURCE_H@, 1, [dnl
 ; rlimit-fsize = -1
 ; rlimit-data = -1

src/daemon/main.c

@@ -1062,6 +1062,7 @@ int main(int argc, char *argv[]) {
     c->running_as_daemon = conf->daemonize;
     c->disallow_exit = conf->disallow_exit;
     c->flat_volumes = conf->flat_volumes;
+    c->rescue_streams = conf->rescue_streams;
 #ifdef HAVE_DBUS
     c->server_type = conf->local_server_type;
 #endif

src/pulsecore/core.h

@@ -213,6 +213,7 @@ struct pa_core {
     int exit_idle_time, scache_idle_time;
 
     bool flat_volumes:1;
+    bool rescue_streams:1;
     bool disallow_module_loading:1;
     bool disallow_exit:1;
     bool running_as_daemon:1;

src/pulsecore/device-port.c

@@ -105,9 +105,10 @@ void pa_device_port_set_available(pa_device_port *p, pa_available_t status) {
 
             sink = pa_device_port_get_sink(p);
             if (sink && p == sink->active_port) {
-                if (sink->active_port->available == PA_AVAILABLE_NO)
-                    pa_sink_move_streams_to_default_sink(p->core, sink, false);
-                else
+                if (sink->active_port->available == PA_AVAILABLE_NO) {
+                    if (p->core->rescue_streams)
+                        pa_sink_move_streams_to_default_sink(p->core, sink, false);
+                } else
                     pa_core_move_streams_to_newly_available_preferred_sink(p->core, sink);
             }
         } else {
@@ -115,9 +116,10 @@ void pa_device_port_set_available(pa_device_port *p, pa_available_t status) {
 
             source = pa_device_port_get_source(p);
             if (source && p == source->active_port) {
-                if (source->active_port->available == PA_AVAILABLE_NO)
-                    pa_source_move_streams_to_default_source(p->core, source, false);
-                else
+                if (source->active_port->available == PA_AVAILABLE_NO) {
+                    if (p->core->rescue_streams)
+                        pa_source_move_streams_to_default_source(p->core, source, false);
+                } else
                     pa_core_move_streams_to_newly_available_preferred_source(p->core, source);
             }
         }

src/pulsecore/sink-input.c

@@ -1980,7 +1980,7 @@ void pa_sink_input_fail_move(pa_sink_input *i) {
         return;
 
     /* Can we move the sink input to the default sink? */
-    if (pa_sink_input_may_move_to(i, i->core->default_sink)) {
+    if (i->core->rescue_streams && pa_sink_input_may_move_to(i, i->core->default_sink)) {
         if (pa_sink_input_finish_move(i, i->core->default_sink, false) >= 0)
             return;
     }

src/pulsecore/sink.c

@@ -762,7 +762,7 @@ void pa_sink_unlink(pa_sink* s) {
 
     pa_core_update_default_sink(s->core);
 
-    if (linked)
+    if (linked && s->core->rescue_streams)
 	pa_sink_move_streams_to_default_sink(s->core, s, false);
 
     if (s->card)

src/pulsecore/source-output.c

@@ -1607,7 +1607,7 @@ void pa_source_output_fail_move(pa_source_output *o) {
         return;
 
     /* Can we move the source output to the default source? */
-    if (pa_source_output_may_move_to(o, o->core->default_source)) {
+    if (o->core->rescue_streams && pa_source_output_may_move_to(o, o->core->default_source)) {
         if (pa_source_output_finish_move(o, o->core->default_source, false) >= 0)
             return;
     }

src/pulsecore/source.c

@@ -702,7 +702,7 @@ void pa_source_unlink(pa_source *s) {
 
     pa_core_update_default_source(s->core);
 
-    if (linked)
+    if (linked && s->core->rescue_streams)
 	pa_source_move_streams_to_default_source(s->core, s, false);
 
     if (s->card)