From 5c2ceb349019e98108c0c8a451646742bb76848a Mon Sep 17 00:00:00 2001
From: Jim Broadus <jbroadus@gmail.com>
Date: Mon, 25 Mar 2019 22:37:15 -0700
Subject: [PATCH] Fix several gstreamer object leaks.

There are a number of cases where gst_pipeline_get_bus,
gst_element_get_static_pad, and g_object_get are called without releasing
references. In addition to memory usage, some of these elements hold file
descriptors. In normal operation, two file descriptors are leaked for each
played track. The default fd ulimit for many linux distros is 1024. This
is likely the cause of the crash reported in issue 6309.

This change fixes the obvious and consistent leaks, but it's probably not a
complete solution. There are many error and corner conditions that need to be
examined.
---
 src/engines/gstenginepipeline.cpp | 32 +++++++++++++++++++------------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/src/engines/gstenginepipeline.cpp b/src/engines/gstenginepipeline.cpp
index 7f12c2628..17ddd6089 100644
--- a/src/engines/gstenginepipeline.cpp
+++ b/src/engines/gstenginepipeline.cpp
@@ -417,10 +417,13 @@ bool GstEnginePipeline::Init() {
   gst_element_link(probe_converter, probe_sink);
 
   // Link the outputs of tee to the queues on each path.
-  gst_pad_link(gst_element_get_request_pad(tee, "src_%u"),
-               gst_element_get_static_pad(probe_queue, "sink"));
-  gst_pad_link(gst_element_get_request_pad(tee, "src_%u"),
-               gst_element_get_static_pad(audio_queue, "sink"));
+  pad = gst_element_get_static_pad(probe_queue, "sink");
+  gst_pad_link(gst_element_get_request_pad(tee, "src_%u"), pad);
+  gst_object_unref(pad);
+
+  pad = gst_element_get_static_pad(audio_queue, "sink");
+  gst_pad_link(gst_element_get_request_pad(tee, "src_%u"), pad);
+  gst_object_unref(pad);
 
   // Link replaygain elements if enabled.
   if (rg_enabled_) {
@@ -454,12 +457,14 @@ bool GstEnginePipeline::Init() {
   gst_caps_unref(caps);
 
   // Add probes and handlers.
-  gst_pad_add_probe(gst_element_get_static_pad(probe_converter, "src"),
-                    GST_PAD_PROBE_TYPE_BUFFER, HandoffCallback, this, nullptr);
-  gst_bus_set_sync_handler(gst_pipeline_get_bus(GST_PIPELINE(pipeline_)),
-                           BusCallbackSync, this, nullptr);
-  bus_cb_id_ = gst_bus_add_watch(gst_pipeline_get_bus(GST_PIPELINE(pipeline_)),
-                                 BusCallback, this);
+  pad = gst_element_get_static_pad(probe_converter, "src");
+  gst_pad_add_probe(pad, GST_PAD_PROBE_TYPE_BUFFER, HandoffCallback, this,
+                    nullptr);
+  gst_object_unref(pad);
+  GstBus *bus = gst_pipeline_get_bus(GST_PIPELINE(pipeline_));
+  gst_bus_set_sync_handler(bus, BusCallbackSync, this, nullptr);
+  bus_cb_id_ = gst_bus_add_watch(bus, BusCallback, this);
+  gst_object_unref(bus);
 
   MaybeLinkDecodeToAudio();
 
@@ -519,8 +524,10 @@ bool GstEnginePipeline::InitFromUrl(const QUrl& url, qint64 end_nanosec) {
 
 GstEnginePipeline::~GstEnginePipeline() {
   if (pipeline_) {
-    gst_bus_set_sync_handler(gst_pipeline_get_bus(GST_PIPELINE(pipeline_)),
-                             nullptr, nullptr, nullptr);
+    GstBus *bus = gst_pipeline_get_bus(GST_PIPELINE(pipeline_));
+    gst_bus_set_sync_handler(bus, nullptr, nullptr, nullptr);
+    gst_object_unref(bus);
+
     g_source_remove(bus_cb_id_);
     gst_element_set_state(pipeline_, GST_STATE_NULL);
     gst_object_unref(GST_OBJECT(pipeline_));
@@ -1011,6 +1018,7 @@ void GstEnginePipeline::SourceSetupCallback(GstURIDecodeBin* bin,
     g_object_set(element, "ssl-strict", TRUE, nullptr);
 #endif
   }
+  g_object_unref(element);
 }
 
 void GstEnginePipeline::TransitionToNext() {