core: make sure we always return a valid memblock in sink_input_pop() callbacks

https://bugzilla.redhat.com/show_bug.cgi?id=553607

src/modules/module-combine.c

@@ -890,7 +890,7 @@ static struct output *output_new(struct userdata *u, pa_sink *sink) {
             1,
             0,
             0,
-            NULL);
+            &u->sink->silence);
 
     pa_assert_se(pa_idxset_put(u->outputs, o, NULL) == 0);
     update_description(u);

src/modules/module-ladspa-sink.c

@@ -476,6 +476,7 @@ int pa__init(pa_module*m) {
     unsigned long input_port, output_port, p, j, n_control;
     unsigned c;
     pa_bool_t *use_default = NULL;
+    pa_memchunk silence;
 
     pa_assert(m);
 
@@ -514,7 +515,10 @@ int pa__init(pa_module*m) {
     u = pa_xnew0(struct userdata, 1);
     u->module = m;
     m->userdata = u;
-    u->memblockq = pa_memblockq_new(0, MEMBLOCKQ_MAXLENGTH, 0, pa_frame_size(&ss), 1, 1, 0, NULL);
+
+    pa_silence_memchunk_get(&m->core->silence_cache, m->core->mempool, &silence, &ss, 0);
+    u->memblockq = pa_memblockq_new(0, MEMBLOCKQ_MAXLENGTH, 0, pa_frame_size(&ss), 1, 1, 0, &silence);
+    pa_memblock_unref(silence.memblock);
 
     if (!(e = getenv("LADSPA_PATH")))
         e = LADSPA_PATH;

src/pulsecore/play-memchunk.c

@@ -47,12 +47,16 @@ int pa_play_memchunk(
 
     pa_memblockq *q;
     int r;
+    pa_memchunk silence;
 
     pa_assert(sink);
     pa_assert(ss);
     pa_assert(chunk);
 
-    q = pa_memblockq_new(0, chunk->length, 0, pa_frame_size(ss), 1, 1, 0, NULL);
+    pa_silence_memchunk_get(&sink->core->silence_cache, sink->core->mempool, &silence, ss, 0);
+    q = pa_memblockq_new(0, chunk->length, 0, pa_frame_size(ss), 1, 1, 0, &silence);
+    pa_memblock_unref(silence.memblock);
+
     pa_assert_se(pa_memblockq_push(q, chunk) >= 0);
 
     if ((r = pa_play_memblockq(sink, ss, map, q, volume, p, sink_input_index)) < 0) {

src/pulsecore/protocol-esound.c

@@ -389,6 +389,7 @@ static int esd_proto_stream_play(connection *c, esd_proto_t request, const void
     size_t l;
     pa_sink *sink = NULL;
     pa_sink_input_new_data sdata;
+    pa_memchunk silence;
 
     connection_assert_ref(c);
     pa_assert(data);
@@ -435,6 +436,7 @@ static int esd_proto_stream_play(connection *c, esd_proto_t request, const void
     CHECK_VALIDITY(c->sink_input, "Failed to create sink input.");
 
     l = (size_t) ((double) pa_bytes_per_second(&ss)*PLAYBACK_BUFFER_SECONDS);
+    pa_sink_input_get_silence(c->sink_input, &silence);
     c->input_memblockq = pa_memblockq_new(
             0,
             l,
@@ -443,7 +445,8 @@ static int esd_proto_stream_play(connection *c, esd_proto_t request, const void
             (size_t) -1,
             l/PLAYBACK_BUFFER_FRAGMENTS,
             0,
-            NULL);
+            &silence);
+    pa_memblock_unref(silence.memblock);
     pa_iochannel_socket_set_rcvbuf(c->io, l);
 
     c->sink_input->parent.process_msg = sink_input_process_msg;

src/pulsecore/protocol-simple.c

@@ -525,6 +525,7 @@ void pa_simple_protocol_connect(pa_simple_protocol *p, pa_iochannel *io, pa_simp
 
     if (o->playback) {
         pa_sink_input_new_data data;
+        pa_memchunk silence;
         size_t l;
         pa_sink *sink;
 
@@ -559,6 +560,7 @@ void pa_simple_protocol_connect(pa_simple_protocol *p, pa_iochannel *io, pa_simp
         pa_sink_input_set_requested_latency(c->sink_input, DEFAULT_SINK_LATENCY);
 
         l = (size_t) ((double) pa_bytes_per_second(&o->sample_spec)*PLAYBACK_BUFFER_SECONDS);
+        pa_sink_input_get_silence(c->sink_input, &silence);
         c->input_memblockq = pa_memblockq_new(
                 0,
                 l,
@@ -567,7 +569,9 @@ void pa_simple_protocol_connect(pa_simple_protocol *p, pa_iochannel *io, pa_simp
                 (size_t) -1,
                 l/PLAYBACK_BUFFER_FRAGMENTS,
                 0,
-                NULL);
+                &silence);
+        pa_memblock_unref(silence.memblock);
+
         pa_iochannel_socket_set_rcvbuf(io, l);
 
         pa_atomic_store(&c->playback.missing, (int) pa_memblockq_missing(c->input_memblockq));

src/pulsecore/sound-file-stream.c

@@ -239,6 +239,7 @@ int pa_play_file(
     pa_sink_input_new_data data;
     int fd;
     SF_INFO sfi;
+    pa_memchunk silence;
 
     pa_assert(sink);
     pa_assert(fname);
@@ -324,7 +325,9 @@ int pa_play_file(
     u->sink_input->state_change = sink_input_state_change_cb;
     u->sink_input->userdata = u;
 
-    u->memblockq = pa_memblockq_new(0, MEMBLOCKQ_MAXLENGTH, 0, pa_frame_size(&ss), 1, 1, 0, NULL);
+    pa_sink_input_get_silence(u->sink_input, &silence);
+    u->memblockq = pa_memblockq_new(0, MEMBLOCKQ_MAXLENGTH, 0, pa_frame_size(&ss), 1, 1, 0, &silence);
+    pa_memblock_unref(silence.memblock);
 
     pa_sink_input_put(u->sink_input);