dll防止卸载,以及阻止crt释放,等

部分dll有时需要在进程中永久有效,如hook, 正常的dll在程序退出时会释放dll, 然后导致dll中的对象被释放(CRT清理)
跟踪源码, 可以看到 在__DllMainCRTStartup 中有调用 _CRT_INIT释放资源,
中间不可控, 但是有一个异常捕获, 尝试生成一个异常, 但是简单异常的过滤条件无法满足
改用自定义入口:

#define _DECL_DLLMAIN
#include <process.h>

#pragma comment(linker, "/ENTRY:DllMainCRTStartup")

extern "C"	BOOL WINAPI DllMainCRTStartup(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpReserved)
{
	BOOL	bRetVal;

	switch(fdwReason)
	{
	case DLL_PROCESS_ATTACH:	
		bRetVal = _CRT_INIT(hinstDLL, fdwReason, lpReserved);
		HookMgr.Init();
		break;
	case DLL_THREAD_ATTACH:		
		bRetVal = _CRT_INIT(hinstDLL, fdwReason, lpReserved);
		break;
	case DLL_PROCESS_DETACH:
		bRetVal = HookMgr.Stop();
		if(bRetVal == FALSE)
			return FALSE;

		bRetVal = _CRT_INIT(hinstDLL, fdwReason, lpReserved);	
		break;
	case DLL_THREAD_DETACH:		
		bRetVal = _CRT_INIT(hinstDLL, fdwReason, lpReserved);
		break;
	default:
		return TRUE;
	}

	return bRetVal;
} 

其他:

1. dll导出 (x86, x64符号命名差异)

pragma comment(linker, "/EXPORT:NsiRpcSetParameterEx=_NopSub@40,PRIVATE")

// x64

pragma comment(linker, "/EXPORT:NsiRpcSetParameterEx=NopSub,PRIVATE")

2. dll导出序号

pragma comment(linker, "/EXPORT:@103=_profapi_10@16,@103,PRIVATE")