__dso_handle 在哪里定义? [英] Where is __dso_handle defined?

问题描述

我在尝试编译我的程序时遇到一个未解决的符号错误，它抱怨它找不到 __dso_handle.这个函数一般定义在哪个库中?

I have an unresolved symbol error when trying to compile my program which complains that it cannot find __dso_handle. Which library is this function usually defined in?

nm on libstdc++.so.6 的以下结果是否意味着它包含该内容?

Does the following result from nm on libstdc++.so.6 mean it contains that?

我试图链接它，但仍然出现错误.

I tried to link against it but the error still occurs.

nm libstdc++.so.6 | grep dso
00000000002fc480 d __dso_handle

推荐答案

__dso_handle 是一个守卫"，即 用于在全局销毁时识别动态共享对象.

__dso_handle is a "guard" that is used to identify dynamic shared objects during global destruction.

实际上，您应该停止阅读这里.如果你试图通过弄乱 __dso_handle 来破坏对象识别，那么很可能是大错特错.

Realistically, you should stop reading here. If you're trying to defeat object identification by messing with __dso_handle, something is likely very wrong.

但是，既然您问它是在哪里定义的:答案很复杂.要显示其定义的位置(对于 GCC)，请在 C++ 文件中使用 iostream，然后执行 extern int __dso_handle;.由于类型冲突，这应该会显示声明的位置(请参阅 此论坛主题 获取来源).

However, since you asked where it is defined: the answer is complex. To surface the location of its definition (for GCC), use iostream in a C++ file, and, after that, do extern int __dso_handle;. That should surface the location of the declaration due to a type conflict (see this forum thread for a source).

有时，它是手动定义的.

有时，它由编译器安装的运行时"定义/提供(实际上，CRT 通常只是一堆二进制标头/入口点管理代码，以及一些出口防护/处理程序).在 GCC 中(不确定其他编译器是否支持这一点；如果支持，它将在他们的源代码中):

Sometimes, it is defined/supplied by the "runtime" installed by the compiler (in practice, the CRT is usually just a bunch of binary header/entry-point-management code, and some exit guards/handlers). In GCC (not sure if other compilers support this; if so, it'll be in their sources):

• 主要定义
• 测试__dso_handle 替换/跟踪器示例 1
• 测试__dso_handle 替换/跟踪器示例 2

• Main definition
• Testing __dso_handle replacement/tracker example 1
• Testing __dso_handle replacement/tracker example 2

通常，它是在标准库中定义的:

Often, it is defined in the stdlib:

• Android
• BSD

进一步阅读:

• 由__dso_handle引起的细微错误在某些编译器中无法访问

• Subtle bugs caused by __dso_handle being unreachable in some compilers

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