Fix for crash when exiting whilst NewGRF scan still in progress

See: https://github.com/OpenTTD/OpenTTD/issues/8760

src/newgrf_config.cpp

@@ -344,6 +344,7 @@ static std::vector<GRFMD5SumState> _grf_md5_pending;
 static std::condition_variable _grf_md5_full_cv;
 static std::condition_variable _grf_md5_empty_cv;
 static std::condition_variable _grf_md5_done_cv;
+static std::atomic<bool> _abort_grf_scan;
 static const uint GRF_MD5_PENDING_MAX = 8;
 
 static void CalcGRFMD5SumFromState(const GRFMD5SumState &state)
@@ -373,7 +374,7 @@ void CalcGRFMD5Thread()
 			_grf_md5_pending.pop_back();
 			lk.unlock();
 			if (full) _grf_md5_full_cv.notify_one();
-			CalcGRFMD5SumFromState(state);
+			if (!_abort_grf_scan.load(std::memory_order_relaxed)) CalcGRFMD5SumFromState(state);
 			lk.lock();
 		}
 	}
@@ -728,6 +729,8 @@ public:
 
 bool GRFFileScanner::AddFile(const std::string &filename, size_t basepath_length, const std::string &tar_filename)
 {
+	if (_abort_grf_scan.load(std::memory_order_relaxed)) return false;
+
 	GRFConfig *c = new GRFConfig(filename.c_str() + basepath_length);
 
 	bool added = FillGRFDetails(c, false);
@@ -846,6 +849,11 @@ void ScanNewGRFFiles(NewGRFScanCallback *callback)
 	}
 }
 
+void AbortScanNewGRFFiles()
+{
+	_abort_grf_scan.store(true, std::memory_order_relaxed);
+}
+
 /**
  * Find a NewGRF in the scanned list.
  * @param grfid GRFID to look for,

src/newgrf_config.h

@@ -222,6 +222,7 @@ struct NewGRFScanCallback {
 size_t GRFGetSizeOfDataSection(FILE *f);
 
 void ScanNewGRFFiles(NewGRFScanCallback *callback);
+void AbortScanNewGRFFiles();
 const GRFConfig *FindGRFConfig(uint32 grfid, FindGRFConfigMode mode, const uint8 *md5sum = nullptr, uint32 desired_version = 0);
 GRFConfig *GetGRFConfig(uint32 grfid, uint32 mask = 0xFFFFFFFF);
 GRFConfig **CopyGRFConfigList(GRFConfig **dst, const GRFConfig *src, bool init_only);

src/openttd.cpp

@@ -1006,8 +1006,10 @@ int openttd_main(int argc, char *argv[])
 
 	CrashLog::MainThreadExitCheckPendingCrashlog();
 
+	AbortScanNewGRFFiles();
 	WaitTillSaved();
 	WaitTillGeneratedWorld(); // Make sure any generate world threads have been joined.
+	WaitUntilModalProgressCompleted();
 
 	/* only save config if we have to */
 	if (_save_config) {

src/progress.cpp

@@ -9,6 +9,7 @@
 
 #include "stdafx.h"
 #include "progress.h"
+#include "video/video_driver.hpp"
 
 #include <chrono>
 #include <mutex>
@@ -64,3 +65,22 @@ void SleepWhileModalProgress(int milliseconds)
 	std::unique_lock<std::mutex> lk(_modal_progress_cv_mutex);
 	_modal_progress_cv.wait_for(lk, std::chrono::milliseconds(milliseconds), []{ return !_in_modal_progress; });
 }
+
+void WaitUntilModalProgressCompleted()
+{
+	if (HasModalProgress()) {
+		_modal_progress_paint_mutex.unlock();
+		_modal_progress_work_mutex.unlock();
+
+		{
+			std::unique_lock<std::mutex> lk(_modal_progress_cv_mutex);
+			_modal_progress_cv.wait(lk, []{ return !_in_modal_progress; });
+		}
+
+		/* Modal progress thread may need blitter access while we are waiting for it. */
+		VideoDriver::GetInstance()->ReleaseBlitterLock();
+		_modal_progress_paint_mutex.lock();
+		VideoDriver::GetInstance()->AcquireBlitterLock();
+		_modal_progress_work_mutex.lock();
+	}
+}

src/progress.h

@@ -40,6 +40,7 @@ static inline bool UseThreadedModelProgress()
 bool IsFirstModalProgressLoop();
 void SetModalProgress(bool state);
 void SleepWhileModalProgress(int milliseconds);
+void WaitUntilModalProgressCompleted();
 
 extern std::mutex _modal_progress_work_mutex;
 extern std::mutex _modal_progress_paint_mutex;