[pulseaudio-discuss] [PATCH] sink/source: Don't update default sink/source before calling PA_CORE_HOOK_{SINK, SOURCE}_PUT

[Georg Chini]

In sink_put() and source_put(), pa_core_update_default_{sink,source}() was called
before the PA_CORE_HOOK_{SINK,SOURCE}_PUT hook. Therefore module-switch-on-connect
could not correctly determine the old default sink/source if no user default was
set and a sink/source with higher priority than any other sink/source turned up.

This patch corrects the problem by swapping the order of the hook call and the
pa_core_update_default_sink() call.

Additionally it corrects a problem in module-switch-on-connect. If, after the
change above, the new sink/source was the first sink/source to appear, pulseaudio
would crash because module-switch-on-connect assumed that the default sink/source
was not NULL. The patch checks if the default sink/source is NULL and only sets
the new default sink/source in that case.
---
 src/modules/module-switch-on-connect.c | 12 ++++++++++++
 src/pulsecore/sink.c                   |  6 ++++--
 src/pulsecore/source.c                 |  6 ++++--
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/modules/module-switch-on-connect.c b/src/modules/module-switch-on-connect.c
index 776c923e..e2da7222 100644
--- a/src/modules/module-switch-on-connect.c
+++ b/src/modules/module-switch-on-connect.c
@@ -75,6 +75,12 @@ static pa_hook_result_t sink_put_hook_callback(pa_core *c, pa_sink *sink, void*
             return PA_HOOK_OK;
     }
 
+    /* No default sink, nothing to move away, just set the new default */
+    if (!c->default_sink) {
+        pa_core_set_configured_default_sink(c, sink);
+        return PA_HOOK_OK;
+    }
+
     if (c->default_sink == sink)
         return PA_HOOK_OK;
 
@@ -135,6 +141,12 @@ static pa_hook_result_t source_put_hook_callback(pa_core *c, pa_source *source,
             return PA_HOOK_OK;
     }
 
+    /* No default source, nothing to move away, just set the new default */
+    if (!c->default_source) {
+        pa_core_set_configured_default_source(c, source);
+        return PA_HOOK_OK;
+    }
+
     if (c->default_source == source)
         return PA_HOOK_OK;
 
diff --git a/src/pulsecore/sink.c b/src/pulsecore/sink.c
index 71121ca0..644c4e49 100644
--- a/src/pulsecore/sink.c
+++ b/src/pulsecore/sink.c
@@ -660,10 +660,12 @@ void pa_sink_put(pa_sink* s) {
 
     pa_source_put(s->monitor_source);
 
-    pa_core_update_default_sink(s->core);
-
     pa_subscription_post(s->core, PA_SUBSCRIPTION_EVENT_SINK | PA_SUBSCRIPTION_EVENT_NEW, s->index);
     pa_hook_fire(&s->core->hooks[PA_CORE_HOOK_SINK_PUT], s);
+
+    /* This function must be called after the PA_CORE_HOOK_SINK_PUT hook,
+     * because module-switch-on-connect needs to know the old default sink */
+    pa_core_update_default_sink(s->core);
 }
 
 /* Called from main context */
diff --git a/src/pulsecore/source.c b/src/pulsecore/source.c
index 15b1eecd..7eef2093 100644
--- a/src/pulsecore/source.c
+++ b/src/pulsecore/source.c
@@ -603,10 +603,12 @@ void pa_source_put(pa_source *s) {
     else
         pa_assert_se(source_set_state(s, PA_SOURCE_IDLE) == 0);
 
-    pa_core_update_default_source(s->core);
-
     pa_subscription_post(s->core, PA_SUBSCRIPTION_EVENT_SOURCE | PA_SUBSCRIPTION_EVENT_NEW, s->index);
     pa_hook_fire(&s->core->hooks[PA_CORE_HOOK_SOURCE_PUT], s);
+
+    /* This function must be called after the PA_CORE_HOOK_SOURCE_PUT hook,
+     * because module-switch-on-connect needs to know the old default source */
+    pa_core_update_default_source(s->core);
 }
 
 /* Called from main context */
-- 
2.11.0