From 969427980492f5079e197bfc3de3551806ee4940 Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@audacityteam.org>
Date: Tue, 17 Oct 2017 06:17:06 -0400
Subject: [PATCH] Guard against crash when stopping a stream...

... caused by remembering a NULL pointer to active project when starting a
stream.

Hard to reproduce, but reported by David Bailes.  We suspect that both the
closing of another project window, and changes of focused application, are
necessary to reproduce the problem.
---
 src/AudioIO.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/AudioIO.cpp b/src/AudioIO.cpp
index a8d145dbc..a78bd1cab 100644
--- a/src/AudioIO.cpp
+++ b/src/AudioIO.cpp
@@ -1643,6 +1643,12 @@ bool AudioIO::StartPortAudioStream(double sampleRate,
    mAudioFramesPerBuffer = 0;
 #endif
    mOwningProject = GetActiveProject();
+
+   // PRL:  Protection from crash reported by David Bailes, involving starting
+   // and stopping with frequent changes of active window, hard to reproduce
+   if (!mOwningProject)
+      return false;
+
    mInputMeter = NULL;
    mOutputMeter = NULL;