From abc69145287ca5395545c4d11f86ac01ef656b6b Mon Sep 17 00:00:00 2001
From: Adriaan de Groot <groot@kde.org>
Date: Wed, 17 Jan 2018 06:18:43 -0500
Subject: [PATCH] [libcalamares] Enforce singleton-ness of
 CalamaresPython::Helper

 - unset instance pointer on destruction
 - make constructor private, and the instance accessor
   should create an instance if there isn't one.
---
 src/libcalamares/JobQueue.cpp     | 3 ---
 src/libcalamares/PythonHelper.cpp | 4 +++-
 src/libcalamares/PythonHelper.h   | 2 +-
 src/libcalamares/PythonJob.cpp    | 6 ++++--
 4 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/libcalamares/JobQueue.cpp b/src/libcalamares/JobQueue.cpp
index 3a2e9ff03..b5bdf0543 100644
--- a/src/libcalamares/JobQueue.cpp
+++ b/src/libcalamares/JobQueue.cpp
@@ -41,9 +41,6 @@ public:
         , m_queue( queue )
         , m_jobIndex( 0 )
     {
-#ifdef WITH_PYTHON
-        new CalamaresPython::Helper( this );
-#endif
     }
 
     void setJobs( const JobList& jobs )
diff --git a/src/libcalamares/PythonHelper.cpp b/src/libcalamares/PythonHelper.cpp
index 4f2f30e76..f274ac276 100644
--- a/src/libcalamares/PythonHelper.cpp
+++ b/src/libcalamares/PythonHelper.cpp
@@ -231,7 +231,9 @@ Helper::Helper( QObject* parent )
 }
 
 Helper::~Helper()
-{}
+{
+    s_instance = nullptr;
+}
 
 
 boost::python::dict
diff --git a/src/libcalamares/PythonHelper.h b/src/libcalamares/PythonHelper.h
index e552a869d..d48e5eaab 100644
--- a/src/libcalamares/PythonHelper.h
+++ b/src/libcalamares/PythonHelper.h
@@ -48,7 +48,6 @@ class Helper : public QObject
 {
     Q_OBJECT
 public:
-    explicit Helper( QObject* parent = nullptr );
     virtual ~Helper();
 
     boost::python::dict createCleanNamespace();
@@ -57,6 +56,7 @@ public:
 
 private:
     friend Helper* Calamares::PythonJob::helper();
+    explicit Helper( QObject* parent = nullptr );
     static Helper* s_instance;
 
     boost::python::object m_mainModule;
diff --git a/src/libcalamares/PythonJob.cpp b/src/libcalamares/PythonJob.cpp
index faf2fa72d..a9fe4463e 100644
--- a/src/libcalamares/PythonJob.cpp
+++ b/src/libcalamares/PythonJob.cpp
@@ -381,8 +381,10 @@ PythonJob::emitProgress( qreal progressValue )
 CalamaresPython::Helper*
 PythonJob::helper()
 {
-    return CalamaresPython::Helper::s_instance;
-
+    auto ptr = CalamaresPython::Helper::s_instance;
+    if (!ptr)
+        ptr = new CalamaresPython::Helper;
+    return ptr;
 }