From a8b018d5da211c87eeebd513c3656dd8a444d144 Mon Sep 17 00:00:00 2001
From: Geoffrey McRae <geoff@hostfission.com>
Date: Mon, 4 Mar 2019 13:38:17 +1100
Subject: [PATCH] [c-host] app: fix updateEvent race problem

---
 c-host/app.c                  | 19 +++++++------------
 c-host/app.h                  |  5 +++--
 c-host/windows/capture/dxgi.c |  2 +-
 c-host/windows/platform.c     | 15 +++++++++++++--
 4 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/c-host/app.c b/c-host/app.c
index 3abb6fcd..206c148d 100644
--- a/c-host/app.c
+++ b/c-host/app.c
@@ -62,11 +62,8 @@ static int pointerThread(void * opaque)
 {
   DEBUG_INFO("Cursor thread started");
 
-  while(app.running)
+  while(os_waitEvent(app.pointerEvent) && app.running)
   {
-    if (!os_waitEvent(app.pointerEvent) || !app.running)
-      break;
-
 #if 0
     CapturePointer pointer;
     pointer->data = app.pointerData;
@@ -87,11 +84,8 @@ static int frameThread(void * opaque)
   int      frameIndex = 0;
   volatile KVMFRFrame * fi = &(app.shmHeader->frame);
 
-  while(app.running)
+  while(os_waitEvent(app.frameEvent) && app.running)
   {
-    if (!os_waitEvent(app.frameEvent) || !app.running)
-      break;
-
     CaptureFrame frame;
     frame.data = app.frame[frameIndex];
     if (!app.iface->getFrame(&frame))
@@ -105,7 +99,7 @@ static int frameThread(void * opaque)
     os_signalEvent(app.updateEvent);
 
     // wait for the client to finish with the previous frame
-    while(fi->flags & KVMFR_FRAME_FLAG_UPDATE)
+    while(fi->flags & KVMFR_FRAME_FLAG_UPDATE && app.running)
     {
       DEBUG_WARN("Waiting for the client");
       // this generally never happens
@@ -277,7 +271,7 @@ int app_main()
   }
 
   app.iface      = iface;
-  app.frameEvent = os_createEvent();
+  app.frameEvent = os_createEvent(true);
   if (!app.frameEvent)
   {
     DEBUG_ERROR("Failed to create the frame event");
@@ -285,7 +279,7 @@ int app_main()
     goto exit;
   }
 
-  app.updateEvent = os_createEvent();
+  app.updateEvent = os_createEvent(false);
   if (!app.updateEvent)
   {
     DEBUG_ERROR("Failed to create the update event");
@@ -293,7 +287,7 @@ int app_main()
     goto exit;
   }
 
-  app.pointerEvent = os_createEvent();
+  app.pointerEvent = os_createEvent(true);
   if (!app.pointerEvent)
   {
     DEBUG_ERROR("Failed to create the pointer event");
@@ -365,6 +359,7 @@ retry_capture:
     if (!frameUpdate && !pointerUpdate)
       goto retry_capture;
 
+    os_resetEvent(app.updateEvent);
     if (frameUpdate && !os_signalEvent(app.frameEvent))
     {
       DEBUG_ERROR("Failed to signal the frame thread");
diff --git a/c-host/app.h b/c-host/app.h
index 1c4c894c..32783dd7 100644
--- a/c-host/app.h
+++ b/c-host/app.h
@@ -42,7 +42,8 @@ bool         os_joinThread  (osThreadHandle * handle, int * resultCode);
 
 typedef struct osEventHandle osEventHandle;
 
-osEventHandle * os_createEvent();
+osEventHandle * os_createEvent(bool autoReset);
 void            os_freeEvent  (osEventHandle * handle);
 bool            os_waitEvent  (osEventHandle * handle);
-bool            os_signalEvent(osEventHandle * handle);
\ No newline at end of file
+bool            os_signalEvent(osEventHandle * handle);
+bool            os_resetEvent (osEventHandle * handle);
\ No newline at end of file
diff --git a/c-host/windows/capture/dxgi.c b/c-host/windows/capture/dxgi.c
index 2178ae56..f4d49b3b 100644
--- a/c-host/windows/capture/dxgi.c
+++ b/c-host/windows/capture/dxgi.c
@@ -76,7 +76,7 @@ static bool dxgi_create()
     return false;
   }
 
-  this->copyEvent = os_createEvent();
+  this->copyEvent = os_createEvent(true);
   if (!this->copyEvent)
   {
     DEBUG_ERROR("failed to create the copy event");
diff --git a/c-host/windows/platform.c b/c-host/windows/platform.c
index 33b20ccb..f8997815 100644
--- a/c-host/windows/platform.c
+++ b/c-host/windows/platform.c
@@ -300,9 +300,15 @@ bool os_joinThread(osThreadHandle * handle, int * resultCode)
   return false;
 }
 
-osEventHandle * os_createEvent()
+osEventHandle * os_createEvent(bool autoReset)
 {
-  HANDLE event = CreateEvent(NULL, FALSE, FALSE, NULL);
+  HANDLE event = CreateEvent(NULL, autoReset ? FALSE : TRUE, FALSE, NULL);
+  if (!event)
+  {
+    DEBUG_WINERROR("Failed to create the event", GetLastError());
+    return NULL;
+  }
+
   return (osEventHandle*)event;
 }
 
@@ -337,4 +343,9 @@ bool os_waitEvent(osEventHandle * handle)
 bool os_signalEvent(osEventHandle * handle)
 {
   return SetEvent((HANDLE)handle);
+}
+
+bool os_resetEvent(osEventHandle * handle)
+{
+  return ResetEvent((HANDLE)handle);
 }
\ No newline at end of file