From 1bc12ba2b3bc2c4fbe8fad4797cf33266eb13f4b Mon Sep 17 00:00:00 2001
From: Tiger Wang <ziwei.tiger@outlook.com>
Date: Thu, 23 Jul 2020 00:34:43 +0100
Subject: Streamline startup sequence

* Clean up cRoot & main
* Move some OS-specifics into OSSupport
---
 src/OSSupport/MiniDumpWriter.h | 139 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 src/OSSupport/MiniDumpWriter.h

(limited to 'src/OSSupport/MiniDumpWriter.h')

diff --git a/src/OSSupport/MiniDumpWriter.h b/src/OSSupport/MiniDumpWriter.h
new file mode 100644
index 000000000..e5cd1a0ac
--- /dev/null
+++ b/src/OSSupport/MiniDumpWriter.h
@@ -0,0 +1,139 @@
+
+#pragma once
+
+
+
+
+
+/** Flags to control minidump contents on supported platforms. */
+enum class MiniDumpFlags
+{
+	WithDataSegments,
+	WithFullMemory
+};
+
+
+
+
+
+#if defined(_WIN32) && !defined(_WIN64) && defined(_MSC_VER)  // 32-bit Windows app compiled in MSVC
+
+#include <dbghelp.h>
+
+
+
+
+
+/** Windows 32-bit stuff:
+When the server crashes, create a "dump file" containing the callstack of each thread and some variables;
+let the user send us that crash file for analysis */
+class MiniDumpWriter
+{
+	typedef BOOL(WINAPI *pMiniDumpWriteDump)(
+		HANDLE hProcess,
+		DWORD ProcessId,
+		HANDLE hFile,
+		MINIDUMP_TYPE DumpType,
+		PMINIDUMP_EXCEPTION_INFORMATION ExceptionParam,
+		PMINIDUMP_USER_STREAM_INFORMATION UserStreamParam,
+		PMINIDUMP_CALLBACK_INFORMATION CallbackParam
+	);
+
+public:
+
+	MiniDumpWriter()
+	{
+		// Magic code to produce dump-files on Windows if the server crashes:
+
+		m_DbgHelp = LoadLibrary(L"DBGHELP.DLL");
+		if (m_DbgHelp == INVALID_HANDLE_VALUE)
+		{
+			return;
+		}
+
+		s_WriteMiniDump = (pMiniDumpWriteDump)GetProcAddress(m_DbgHelp, "MiniDumpWriteDump");
+		if (s_WriteMiniDump != nullptr)
+		{
+			ASSERT(swprintf(s_DumpFileName, ARRAYCOUNT(s_DumpFileName), L"crash_mcs_%x.dmp", GetCurrentProcessId()) > 0);
+			SetUnhandledExceptionFilter(LastChanceExceptionFilter);
+		}
+
+		// End of dump-file magic
+	}
+
+	void AddDumpFlags(const MiniDumpFlags a_Flags)
+	{
+		switch (a_Flags)
+		{
+			case MiniDumpFlags::WithDataSegments:
+			{
+				s_DumpFlags = static_cast<MINIDUMP_TYPE>(s_DumpFlags | MINIDUMP_TYPE::MiniDumpWithDataSegs);
+				break;
+			}
+			case MiniDumpFlags::WithFullMemory:
+			{
+				s_DumpFlags = static_cast<MINIDUMP_TYPE>(s_DumpFlags | MINIDUMP_TYPE::MiniDumpWithFullMemory);
+				break;
+			}
+		}
+	}
+
+	~MiniDumpWriter()
+	{
+		FreeLibrary(m_DbgHelp);
+	}
+
+private:
+
+	/** This function gets called just before the "program executed an illegal instruction and will be terminated" or similar.
+	Its purpose is to create the crashdump using the dbghlp DLLs */
+	static LONG WINAPI LastChanceExceptionFilter(__in struct _EXCEPTION_POINTERS * a_ExceptionInfo)
+	{
+		char * newStack = &s_ExceptionStack[sizeof(s_ExceptionStack) - 1];
+		char * oldStack;
+
+		// Use the substitute stack:
+		// This code is the reason why we don't support 64-bit (yet)
+		_asm
+		{
+			mov oldStack, esp
+			mov esp, newStack
+		}
+
+		MINIDUMP_EXCEPTION_INFORMATION  ExcInformation;
+		ExcInformation.ThreadId = GetCurrentThreadId();
+		ExcInformation.ExceptionPointers = a_ExceptionInfo;
+		ExcInformation.ClientPointers = 0;
+
+		// Write the dump file:
+		HANDLE dumpFile = CreateFile(s_DumpFileName, GENERIC_WRITE, 0, nullptr, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, nullptr);
+		s_WriteMiniDump(GetCurrentProcess(), GetCurrentProcessId(), dumpFile, s_DumpFlags, (a_ExceptionInfo) ? &ExcInformation : nullptr, nullptr, nullptr);
+		CloseHandle(dumpFile);
+
+		// Revert to old stack:
+		_asm
+		{
+			mov esp, oldStack
+		}
+
+		return 0;
+	}
+
+	HINSTANCE m_DbgHelp;
+
+	static inline pMiniDumpWriteDump s_WriteMiniDump;  // The function in dbghlp DLL that creates dump files
+	static inline wchar_t s_DumpFileName[MAX_PATH];  // Filename of the dump file; hes to be created before the dump handler kicks in
+	static inline char s_ExceptionStack[128 * 1024];  // Substitute stack, just in case the handler kicks in because of "insufficient stack space"
+	static inline MINIDUMP_TYPE s_DumpFlags = MiniDumpNormal;  // By default dump only the stack and some helpers
+};
+
+#else
+
+struct MiniDumpWriter
+{
+	void AddDumpFlags(const MiniDumpFlags)
+	{
+	}
+};
+
+#endif
-- 
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