使用-Bsymbolic-functions有不利之处吗? [英] Is there a downside to using -Bsymbolic-functions?

问题描述

我最近在GNU ld中发现了链接器选项"-Bsymbolic-functions":

I recently discovered the linker option "-Bsymbolic-functions" in GNU ld:

-Bsymbolic
  When creating a shared library, bind references to global symbols to the 
  definition within the shared library, if any. Normally, it is possible 
  for a program linked against a shared library to override the definition 
  within the shared library. 

  This option is only meaningful on ELF platforms which support shared libraries.

-Bsymbolic-functions
  When creating a shared library, bind references to global function symbols 
  to the definition within the shared library, if any.  

  This option is only meaningful on ELF platforms which support shared libraries.

这似乎是GCC选项-fvisibility=hidden的反函数，它不是阻止将引用函数导出到其他共享库，而是防止了对该函数的库内部引用绑定到导出函数不同的共享对象.我告诉自己，-Bsymbolic-functions将阻止创建该功能的PLT条目，这是一个很好的副作用.

This seems to be the inverse of the GCC option -fvisibility=hidden, in that instead of preventing the export of the referenced function to other shared objects, it prevents library-internal references to that function from being bound to an an exported function of a different shared object. I informed myself that -Bsymbolic-functions will prevent the creation of PLT entries for the functions, which is a nice side effect.

1. 但是我想知道是否可能对此进行更细粒度的控制，例如为库的单个函数定义覆盖-Bsymbolic.

我是否应该知道使用-Bsymbolic-functions的任何陷阱?我打算只使用它，因为我认为-Bsymbolic会打破异常(我认为这样做会使得对typeinfo对象的引用不统一).

Should I be aware of any pitfalls of using -Bsymbolic-functions? I plan to only use that, because the -Bsymbolic will break exceptions, I think (it will make it so that references to typeinfo objects are not unified, I think).

谢谢！

推荐答案

回答我自己的问题，因为我刚刚为此获得了风滚草徽章...后来我发现了

Answering my own question because I just earned a Tumbleweed badge for it... and I found out subsequently

但是我想知道是否可以对此进行更细粒度的控制，例如为库的单个函数定义覆盖-Bsymbolic.

是的，有一个选项--dynamic-list可以做到这一点

Yes, there is the option --dynamic-list which does exactly that

我应该知道使用-Bsymbolic-functions有什么陷阱吗?我打算只使用它，因为我认为-Bsymbolic会打破异常(我认为这样做是为了使对typeinfo对象的引用不统一).

Should I be aware of any pitfalls of using -Bsymbolic-functions? I plan to only use that, because the -Bsymbolic will break exceptions, I think (it will make it so that references to typeinfo objects are not unified, I think).

我仔细研究了一下，看来没有问题. libstdc ++库显然是这样做的，或者至少是考虑过的，他们只需要添加--dynamic-list-cpp-new即可使operator new保持统一(以防止程序中多个分配器/解除分配器混合在一起的问题，但我认为这样的程序已损坏反正). Ubuntu使用它或默认使用它，似乎它与某些软件包引起冲突.但总体而言，我期望它应该能很好地工作.

I looked more into it, and it seems there is no issue. The libstdc++ library apparently does it or at least did consider it and they only had to add --dynamic-list-cpp-new to still have operator new unified (to prevent issues with multiple allocator / deallocators mixing up in a program but I would argue such programs are broken anyway). Ubuntu uses it or used it by default, and it seems it causes conflicts with some packages. But overall it should work nicely I expect.

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