From 28ab0947c7fbf4224ece0d902be9f946807015d8 Mon Sep 17 00:00:00 2001
From: Stanislaw Halik <sthalik@misaki.pl>
Date: Wed, 10 Aug 2016 16:54:06 +0200
Subject: dinput: prevent freeing handle despite static initializer order

---
 opentrack-dinput/dinput.cpp | 66 ++++++++++++++++++++++++++++++---------------
 1 file changed, 44 insertions(+), 22 deletions(-)

(limited to 'opentrack-dinput/dinput.cpp')

diff --git a/opentrack-dinput/dinput.cpp b/opentrack-dinput/dinput.cpp
index ce80fe0e..06b5e4f2 100644
--- a/opentrack-dinput/dinput.cpp
+++ b/opentrack-dinput/dinput.cpp
@@ -3,22 +3,11 @@
 #include "dinput.hpp"
 #include <QDebug>
 
-dinput_handle dinput_handle::self;
+std::atomic<int> dinput_handle::refcnt;
+std::atomic_flag dinput_handle::init_lock = ATOMIC_FLAG_INIT;
+dinput_handle::di_t dinput_handle::handle(dinput_handle::make_di());
 
-dinput_handle::dinput_handle() : handle(init_di())
-{
-}
-
-dinput_handle::~dinput_handle()
-{
-    if (handle)
-    {
-        handle->Release();
-        handle = nullptr;
-    }
-}
-
-dinput_handle::di_t dinput_handle::init_di()
+LPDIRECTINPUT8& dinput_handle::init_di()
 {
     HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
     if (FAILED(hr))
@@ -27,13 +16,9 @@ dinput_handle::di_t dinput_handle::init_di()
     static LPDIRECTINPUT8 di_ = nullptr;
     if (di_ == nullptr)
     {
-        if (SUCCEEDED(DirectInput8Create(GetModuleHandle(NULL), DIRECTINPUT_VERSION, IID_IDirectInput8, (void**)&di_, NULL)))
-        {
-            return di_;
-        }
-        else
+        if (!SUCCEEDED(DirectInput8Create(GetModuleHandle(NULL), DIRECTINPUT_VERSION, IID_IDirectInput8, (void**)&di_, NULL)))
         {
-            return di_ = nullptr;
+            di_ = nullptr;
         }
     }
     return di_;
@@ -41,7 +26,44 @@ dinput_handle::di_t dinput_handle::init_di()
 
 dinput_handle::di_t dinput_handle::make_di()
 {
-    return self.handle;
+    while (init_lock.test_and_set()) { /* busy loop */ }
+
+    LPDIRECTINPUT8& ret = init_di();
+
+    init_lock.clear();
+
+    return di_t(ret);
 }
 
 #endif
+
+dinput_handle::di_t::di_t(LPDIRECTINPUT8& handle) : handle(handle)
+{
+    while (init_lock.test_and_set()) { /* busy loop */ }
+
+    refcnt++;
+
+    init_lock.clear();
+}
+
+void dinput_handle::di_t::free_di()
+{
+    if (handle)
+        handle->Release();
+    handle = nullptr;
+}
+
+dinput_handle::di_t::~di_t()
+{
+    while (init_lock.test_and_set()) { /* busy loop */ }
+
+    int refcnt_ = refcnt.fetch_sub(1);
+
+    if (refcnt_ == 1)
+    {
+        qDebug() << "exit: deleting di handle";
+        free_di();
+    }
+
+    init_lock.clear();
+}
-- 
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