PulseAudio: make code more robust

Some asynchronous operations return a pa_operation pointer, which can
be null if the operation fails. In some cases we were not checking that
the returned object was non null, leading to some asserts being raised
in pa_operation_unref.

Change-Id: Iff1cc67b7f79b758fa81d79e658debb1d737b29f
Reviewed-by: Christian Stromme <christian.stromme@qt.io>

1 files changed, 48 insertions, 17 deletions

diff --git a/src/plugins/pulseaudio/qpulseaudioengine.cpp b/src/plugins/pulseaudio/qpulseaudioengine.cpp
index e9510fd6a..b3d5044b7 100644
--- a/src/plugins/pulseaudio/qpulseaudioengine.cpp
+++ b/src/plugins/pulseaudio/qpulseaudioengine.cpp
@@ -170,15 +170,30 @@ static void event_cb(pa_context* context, pa_subscription_event_type_t t, uint32
     case PA_SUBSCRIPTION_EVENT_NEW:
     case PA_SUBSCRIPTION_EVENT_CHANGE:
         switch (facility) {
-        case PA_SUBSCRIPTION_EVENT_SERVER:
-            pa_operation_unref(pa_context_get_server_info(context, serverInfoCallback, userdata));
+        case PA_SUBSCRIPTION_EVENT_SERVER: {
+            pa_operation *op = pa_context_get_server_info(context, serverInfoCallback, userdata);
+            if (op)
+                pa_operation_unref(op);
+            else
+                qWarning("PulseAudioService: failed to get server info");
             break;
-        case PA_SUBSCRIPTION_EVENT_SINK:
-            pa_operation_unref(pa_context_get_sink_info_by_index(context, index, sinkInfoCallback, userdata));
+        }
+        case PA_SUBSCRIPTION_EVENT_SINK: {
+            pa_operation *op = pa_context_get_sink_info_by_index(context, index, sinkInfoCallback, userdata);
+            if (op)
+                pa_operation_unref(op);
+            else
+                qWarning("PulseAudioService: failed to get sink info");
             break;
-        case PA_SUBSCRIPTION_EVENT_SOURCE:
-            pa_operation_unref(pa_context_get_source_info_by_index(context, index, sourceInfoCallback, userdata));
+        }
+        case PA_SUBSCRIPTION_EVENT_SOURCE: {
+            pa_operation *op = pa_context_get_source_info_by_index(context, index, sourceInfoCallback, userdata);
+            if (op)
+                pa_operation_unref(op);
+            else
+                qWarning("PulseAudioService: failed to get source info");
             break;
+        }
         default:
             break;
         }
@@ -328,11 +343,15 @@ void QPulseAudioEngine::prepare()
         pa_context_set_state_callback(m_context, contextStateCallback, this);
 
         pa_context_set_subscribe_callback(m_context, event_cb, this);
-        pa_operation_unref(pa_context_subscribe(m_context,
+        pa_operation *op = pa_context_subscribe(m_context,
                                                 pa_subscription_mask_t(PA_SUBSCRIPTION_MASK_SINK |
                                                                        PA_SUBSCRIPTION_MASK_SOURCE |
                                                                        PA_SUBSCRIPTION_MASK_SERVER),
-                                                NULL, NULL));
+                                                NULL, NULL);
+        if (op)
+            pa_operation_unref(op);
+        else
+            qWarning("PulseAudioService: failed to subscribe to context notifications");
     } else {
         pa_context_unref(m_context);
         m_context = 0;
@@ -376,21 +395,33 @@ void QPulseAudioEngine::updateDevices()
 
     // Get default input and output devices
     pa_operation *operation = pa_context_get_server_info(m_context, serverInfoCallback, this);
-    while (pa_operation_get_state(operation) == PA_OPERATION_RUNNING)
-        pa_threaded_mainloop_wait(m_mainLoop);
-    pa_operation_unref(operation);
+    if (operation) {
+        while (pa_operation_get_state(operation) == PA_OPERATION_RUNNING)
+            pa_threaded_mainloop_wait(m_mainLoop);
+        pa_operation_unref(operation);
+    } else {
+        qWarning("PulseAudioService: failed to get server info");
+    }
 
     // Get output devices
     operation = pa_context_get_sink_info_list(m_context, sinkInfoCallback, this);
-    while (pa_operation_get_state(operation) == PA_OPERATION_RUNNING)
-        pa_threaded_mainloop_wait(m_mainLoop);
-    pa_operation_unref(operation);
+    if (operation) {
+        while (pa_operation_get_state(operation) == PA_OPERATION_RUNNING)
+            pa_threaded_mainloop_wait(m_mainLoop);
+        pa_operation_unref(operation);
+    } else {
+        qWarning("PulseAudioService: failed to get sink info");
+    }
 
     // Get input devices
     operation = pa_context_get_source_info_list(m_context, sourceInfoCallback, this);
-    while (pa_operation_get_state(operation) == PA_OPERATION_RUNNING)
-        pa_threaded_mainloop_wait(m_mainLoop);
-    pa_operation_unref(operation);
+    if (operation) {
+        while (pa_operation_get_state(operation) == PA_OPERATION_RUNNING)
+            pa_threaded_mainloop_wait(m_mainLoop);
+        pa_operation_unref(operation);
+    } else {
+        qWarning("PulseAudioService: failed to get source info");
+    }
 
     unlock();
 }