为什么不从入口点函数调用FreeLibrary？ [英] Why not call FreeLibrary from entry point function?

问题描述

我正在写一个DLL，需要动态调用一个单独的DLL多次。我想保持被调用程序加载，然后只是卸载它，当我的DLL卸载。但根据微软，这是一个坏主意。

I'm writing a DLL that needs to call a separate DLL dynamically multiple times. I would like to keep the callee loaded and then just unload it when my DLL is unloaded. But according to Microsoft, that's a bad idea.

入口点函数只应该
执行简单的初始化任务
，并且不应该调用任何其他DLL
加载或终止函数。对于
示例，在入口点函数
中，不应直接或间接地通过
调用LoadLibrary函数或
LoadLibraryEx函数。另外，
当过程是
时，你不应调用FreeLibrary
函数。

The entry point function should only perform simple initialization tasks and should not call any other DLL loading or termination functions. For example, in the entry point function, you should not directly or indirectly call the LoadLibrary function or the LoadLibraryEx function. Additionally, you should not call the FreeLibrary function when the process is terminating.

这里是令人讨厌的代码。可以有人解释为什么我不应该从我的DLL的入口点调用LoadLibrary和FreeLibrary？

Here's the offending code. Can somebody explain why I shouldn't call LoadLibrary and FreeLibrary from my DLL's entry point?

BOOL APIENTRY DllMain( HANDLE hModule, 
                       DWORD  ul_reason_for_call, 
                       LPVOID lpReserved
                     )
{
switch (ul_reason_for_call) {
    case DLL_PROCESS_DETACH :
            if (hLogLib != NULL) FreeLibrary(hLogLib);
            break;
    }
    return TRUE;
}

推荐答案

答案。

入口点函数应该
只执行简单初始化或
终止任务。它不能调用
LoadLibrary或LoadLibraryEx
函数（或调用
这些函数的函数），因为这可能
在DLL中创建依赖循环
加载顺序。这可能导致在系统
执行其初始化代码之前使用DLL
。
类似地，入口函数
不能在进程终止期间调用FreeLibrary函数
（或调用FreeLibrary的函数）
，因为
，这会导致在系统执行
终止代码后使用
的DLL。

The entry-point function should perform only simple initialization or termination tasks. It must not call the LoadLibrary or LoadLibraryEx function (or a function that calls these functions), because this may create dependency loops in the DLL load order. This can result in a DLL being used before the system has executed its initialization code. Similarly, the entry-point function must not call the FreeLibrary function (or a function that calls FreeLibrary) during process termination, because this can result in a DLL being used after the system has executed its termination code.

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