#include "stdafx.h"

static OSVERSIONINFO GetVersionEx2()
{
	OSVERSIONINFO vi = {sizeof vi};
	GetVersionEx(&vi);
	return vi;
}

static OSVERSIONINFO const vi = GetVersionEx2();



static HMODULE hmodKernel;

static HMODULE GetKernelModule()
{
	if (hmodKernel == nullptr)
	{
		hmodKernel = GetModuleHandle(TEXT("kernel32"));
	}
	return hmodKernel;
}

#define KERNEL32 (GetKernelModule())

#define GET_PROC_ADDRESS(hmod, functionName) reinterpret_cast<decltype(functionName)*>(GetProcAddress((hmod), #functionName))

#define DECLARE_REAL_HOLDER(name) static decltype(name)* name ## _Real

extern "C"
{
	BOOL WINAPI IsDebuggerPresent_Helper()
	{
		DECLARE_REAL_HOLDER(IsDebuggerPresent);
		static bool initialized;
		if (!initialized)
		{
			auto IsDebuggerPresent_Real = GET_PROC_ADDRESS(KERNEL32, IsDebuggerPresent);
			initialized = true;
		}

		if (IsDebuggerPresent_Real != nullptr)
		{
			return IsDebuggerPresent_Real();
		}
		else
		{
			return FALSE;
		}
	}

	void* WINAPI EncodePointer_Helper(void* p)
	{
		DECLARE_REAL_HOLDER(EncodePointer);
		static bool initialized;
		if (!initialized)
		{
			auto EncodePointer_Real = GET_PROC_ADDRESS(KERNEL32, EncodePointer);
			initialized = true;
		}

		if (EncodePointer_Real != nullptr)
		{
			return EncodePointer_Real(p);
		}
		else
		{
			return reinterpret_cast<void*>(reinterpret_cast<DWORD>(p) ^ GetCurrentProcessId());
		}
	}

	void* WINAPI DecodePointer_Helper(void* p)
	{
		DECLARE_REAL_HOLDER(DecodePointer);
		static bool initialized;
		if (!initialized)
		{
			auto DecodePointer_Real = GET_PROC_ADDRESS(KERNEL32, DecodePointer);
			initialized = true;
		}

		if (DecodePointer_Real != nullptr)
		{
			return DecodePointer_Real(p);
		}
		else
		{
			return reinterpret_cast<void*>(reinterpret_cast<DWORD>(p) ^ GetCurrentProcessId());
		}
	}

	BOOL WINAPI IsProcessorFeaturePresent_Helper(DWORD feture)
	{
		DECLARE_REAL_HOLDER(IsProcessorFeaturePresent);
		static bool initialized;
		if (!initialized)
		{
			IsProcessorFeaturePresent_Real = GET_PROC_ADDRESS(KERNEL32, IsProcessorFeaturePresent);
			initialized = true;
		}

		if (IsProcessorFeaturePresent_Real != nullptr)
		{
			return IsProcessorFeaturePresent_Real(feture);
		}
		else
		{
			assert(feture == PF_NX_ENABLED); // ATLから呼ばれる
			return FALSE;
		}
	}

	BOOL WINAPI HeapSetInformation_Helper(HANDLE hHeap, HEAP_INFORMATION_CLASS hic, void* information, SSIZE_T informationLength)
	{
		DECLARE_REAL_HOLDER(HeapSetInformation);
		static bool initialized;
		if (!initialized)
		{
			HeapSetInformation_Real = GET_PROC_ADDRESS(KERNEL32, HeapSetInformation);
			initialized = true;
		}

		if (HeapSetInformation_Real != nullptr)
		{
			return HeapSetInformation_Real(hHeap, hic, information, informationLength);
		}
		else
		{
			return TRUE;
		}
	}

	BOOL WINAPI InitializeCriticalSectionAndSpinCount_Helper(LPCRITICAL_SECTION lpcs, DWORD spinCount)
	{
		DECLARE_REAL_HOLDER(InitializeCriticalSectionAndSpinCount);
		static bool initialized;
		if (!initialized)
		{
			InitializeCriticalSectionAndSpinCount_Real = GET_PROC_ADDRESS(KERNEL32, InitializeCriticalSectionAndSpinCount);
			initialized = true;
		}

		__try
		{
			if (InitializeCriticalSectionAndSpinCount_Real != nullptr)
			{
				OSVERSIONINFO vi = {sizeof vi};
				::GetVersionEx(&vi);
				BOOL ret = InitializeCriticalSectionAndSpinCount_Real(lpcs, spinCount);
				return vi.dwPlatformId == VER_PLATFORM_WIN32_WINDOWS
					? TRUE
					: ret;
			}
			else
			{
				::InitializeCriticalSection(lpcs);
				return TRUE;
			}
		}
		__except(EXCEPTION_EXECUTE_HANDLER)
		{
		}
		return FALSE;
	}

	// Interlocked(Push|Pop)EntrySListは、NXが有効な場合のみ呼ばれる。
	// Windows XP以前はNX対応していないためInterlocked(Push|Pop)EntrySListが呼ばれることはない。
	// そのため、GET_PROC_ADDRESSがnullptrを返すことはないと仮定している。
	// なお、Interlocked(Push|Pop)EntrySListもWindows XPから搭載されている。

	PSLIST_ENTRY WINAPI InterlockedPushEntrySList_Helper(PSLIST_HEADER head, PSLIST_ENTRY entry)
	{
		DECLARE_REAL_HOLDER(InterlockedPushEntrySList);
		if (InterlockedPushEntrySList_Real == nullptr)
		{
			 InterlockedPushEntrySList_Real = GET_PROC_ADDRESS(KERNEL32, InterlockedPushEntrySList);
		}
		assert(InterlockedPushEntrySList_Real != nullptr);
		return InterlockedPushEntrySList_Real(head, entry);
	}

	PSLIST_ENTRY WINAPI InterlockedPopEntrySList_Helper(PSLIST_HEADER head)
	{
		DECLARE_REAL_HOLDER(InterlockedPopEntrySList);
		if (InterlockedPopEntrySList_Real == nullptr)
		{
			 InterlockedPopEntrySList_Real = GET_PROC_ADDRESS(KERNEL32, InterlockedPopEntrySList);
		}
		assert(InterlockedPopEntrySList_Real != nullptr);
		return InterlockedPopEntrySList_Real(head);
	}
}