From 7e2bc21ce3847b530d48d322ce60b6a5fbbbf5b3 Mon Sep 17 00:00:00 2001
From: sharkautarch <128002472+sharkautarch@users.noreply.github.com>
Date: Wed, 28 Feb 2024 09:51:56 -0500
Subject: [PATCH] Prevent SDL_WaitEvent loop from running before wlserver has
 finished initializing

fixes issue #661
---
 src/backend.h     |  3 +++
 src/main.cpp      | 12 +++++++-----
 src/sdlwindow.cpp | 15 +++++++++++++++
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/src/backend.h b/src/backend.h
index 66b3ff9646..4d896b96a2 100644
--- a/src/backend.h
+++ b/src/backend.h
@@ -130,6 +130,9 @@ namespace gamescope
     public:
         virtual ~IBackend() {}
 
+	virtual void latchWait() { return; }
+    	virtual void releaseLatch() { return; } //currently only used by sdl
+
         virtual bool Init() = 0;
         virtual bool PostInit() = 0;
         virtual std::span<const char *const> GetInstanceExtensions() const = 0;
diff --git a/src/main.cpp b/src/main.cpp
index bbc3649de5..254f12e41b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -803,7 +803,7 @@ int main(int argc, char **argv)
 	if ( !GetBackend() )
 	{
 		fprintf( stderr, "Failed to create backend.\n" );
-		return 1;
+		exit(1);
 	}
 
 	g_ForcedNV12ColorSpace = parse_colorspace_string( getenv( "GAMESCOPE_NV12_COLORSPACE" ) );
@@ -811,13 +811,13 @@ int main(int argc, char **argv)
 	if ( !vulkan_init_formats() )
 	{
 		fprintf( stderr, "vulkan_init_formats failed\n" );
-		return 1;
+		exit(1);
 	}
 
 	if ( !vulkan_make_output() )
 	{
 		fprintf( stderr, "vulkan_make_output failed\n" );
-		return 1;
+		exit(1);
 	}
 
 	// Prevent our clients from connecting to the parent compositor
@@ -846,7 +846,7 @@ int main(int argc, char **argv)
 		if ( g_nNestedWidth != 0 )
 		{
 			fprintf( stderr, "Cannot specify -w without -h\n" );
-			return 1;
+			exit(1);
 		}
 		g_nNestedWidth = g_nOutputWidth;
 		g_nNestedHeight = g_nOutputHeight;
@@ -857,7 +857,9 @@ int main(int argc, char **argv)
 	if ( !wlserver_init() )
 	{
 		fprintf( stderr, "Failed to initialize wlserver\n" );
-		return 1;
+		exit(1);
+	} else {
+		GetBackend()->releaseLatch();
 	}
 
 	gamescope_xwayland_server_t *base_server = wlserver_get_xwayland_server(0);
diff --git a/src/sdlwindow.cpp b/src/sdlwindow.cpp
index d07a6bcf04..bf5753453d 100644
--- a/src/sdlwindow.cpp
+++ b/src/sdlwindow.cpp
@@ -115,6 +115,8 @@ namespace gamescope
 		// IBackend
 		/////////////
 
+		virtual void latchWait() override;
+		virtual void releaseLatch() override;
 		virtual bool Init() override;
 		virtual bool PostInit() override;
 		virtual std::span<const char *const> GetInstanceExtensions() const override;
@@ -179,6 +181,7 @@ namespace gamescope
 		std::thread m_SDLThread;
 		std::atomic<SDLInitState> m_eSDLInit = { SDLInitState::SDLInit_Waiting };
 
+		std::atomic<bool> m_sdlLatch = {false};
 		std::atomic<bool> m_bApplicationGrabbed = { false };
 		std::atomic<bool> m_bApplicationVisible = { false };
 		std::atomic<std::shared_ptr<INestedHints::CursorInfo>> m_pApplicationCursor;
@@ -336,6 +339,17 @@ namespace gamescope
 		return true;
 	}
 
+	void CSDLBackend::releaseLatch()
+	{
+		m_sdlLatch = true;
+		m_sdlLatch.notify_one();
+	}
+
+	void CSDLBackend::latchWait()
+	{
+		m_sdlLatch.wait(false);
+	}
+	
 	std::span<const char *const> CSDLBackend::GetInstanceExtensions() const
 	{
 		return std::span<const char *const>{ m_pszInstanceExtensions.begin(), m_pszInstanceExtensions.end() };
@@ -631,6 +645,7 @@ namespace gamescope
 
 		static uint32_t fake_timestamp = 0;
 
+		latchWait();
 		SDL_Event event;
 		while( SDL_WaitEvent( &event ) )
 		{