其中称为第一，DllMain（）还是全局静态对象构造函数？

问题描述

在对象的构造函数中，我正在做一些可能成功或可能不成功的初始化。

是否可能表示DllMain（）中初始化过程的成功或失败？

谢谢。

解决方案

MSDN的文档说：

因为DllMain中的代码可能使用静态对象，所以静态对象必须在DllMain运行于DLL_PROCESS_ATTACH之前构建，并在DLL_PROCESS_DETACH运行后被销毁。

您可以使用简单的测试exe和测试dll来验证这一点。

EXE：

  int _tmain（int argc，_TCHAR * argv []）
 {
 wprintf（LMain，loading library\\\
）; 
 HMODULE h = LoadLibrary（LTest.dll）; 
 
 if（h）
 {
 wprintf（LMain，freeing library\\\
）; 
 FreeLibrary（h）; 
} 
 
 wprintf（LMain，exiting\\\
）; 
 return 0; 
} 
  

DLL：

  struct Moo 
 {
 Moo（）{wprintf（LMoo，constructor\\\
）; } 
〜Moo（）{wprintf（LMoo，destructor\\\
）; } 
}; 
 
 Moo m; 
 
 BOOL APIENTRY DllMain（HMODULE hModule，
 DWORD ul_reason_for_call，
 LPVOID lpReserved）
 {
 switch（ul_reason_for_call）
 {
 case DLL_PROCESS_ATTACH：
 wprintf（LDllMain，DLL_PROCESS_ATTACH\\\
）; 
 break; 
 case DLL_THREAD_ATTACH：
 wprintf（LDllMain，DLL_THREAD_ATTACH\\\
）; 
 break; 
 case DLL_THREAD_DETACH：
 wprintf（LDllMain，DLL_THREAD_DETACH\\\
）; 
 break; 
 case DLL_PROCESS_DETACH：
 wprintf（LDllMain，DLL_PROCESS_DETACH\\\
）; 
 break; 
默认值：
 wprintf（LDllMain，???? \\\
）; 
 break; 
} 
 return TRUE; 
} 
  

这些将一起打印：

  Main，加载库
 Moo，构造函数
 DllMain，DLL_PROCESS_ATTACH 
主库，释放库
 DllMain，DLL_PROCESS_DETACH 
 Moo，destructor 
 Main，exiting 
  

正如你所看到的， DllMain（...，DLL_PROCESS_DETACH，...） DllMain（...，DLL_PROCESS_ATTACH，...） $ c>

I am writing a DLL which defines a global static object.

In the object's constructor I am doing some initialization that may or may not succeed.

Is it possible to signal success or failure of the initialization process in DllMain() ? Which of the two is called first ?

Thank you.

解决方案

MSDN's DllMain documentation says:

Since the code within DllMain may use the static objects, the static objects must be constructed before DllMain is run for DLL_PROCESS_ATTACH, and destroyed after it is run for DLL_PROCESS_DETACH.

You can verify this with a simple test exe and test dll.

EXE:

int _tmain(int argc, _TCHAR* argv[])
{
    wprintf(L"Main, loading library\n");
    HMODULE h = LoadLibrary(L"Test.dll");

    if (h)
    {
        wprintf(L"Main, freeing library\n");
        FreeLibrary(h);
    }

    wprintf(L"Main, exiting\n");
    return 0;
}

DLL:

struct Moo
{
    Moo() { wprintf(L"Moo, constructor\n"); }
    ~Moo() { wprintf(L"Moo, destructor\n"); }
};

Moo m;

BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved)
{
    switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:
        wprintf(L"DllMain, DLL_PROCESS_ATTACH\n");
        break;
    case DLL_THREAD_ATTACH:
        wprintf(L"DllMain, DLL_THREAD_ATTACH\n");
        break;
    case DLL_THREAD_DETACH:
        wprintf(L"DllMain, DLL_THREAD_DETACH\n");
        break;
    case DLL_PROCESS_DETACH:
        wprintf(L"DllMain, DLL_PROCESS_DETACH\n");
        break;
    default:
        wprintf(L"DllMain, ????\n");
        break;
    }
    return TRUE;
}

Together those will print:

Main, loading library
Moo, constructor
DllMain, DLL_PROCESS_ATTACH
Main, freeing library
DllMain, DLL_PROCESS_DETACH
Moo, destructor
Main, exiting

As you can see, the static object is constructed before DllMain(...,DLL_PROCESS_ATTACH,...) and destroyed after DllMain(...,DLL_PROCESS_DETACH,...)

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