如何在现有的libstdc ++中使用备用glibc? [英] How to use alternate glibc with existing libstdc++?

问题描述

我需要使用glibc(2.18)的自编译版本，比系统上的默认版本(2.15)更新.我可以编译和链接C ++程序，但是当我尝试运行它时，出现关于libstdc++.so.6的错误. (C程序似乎可以正常工作.)是否需要针对较新的glibc重新编译gcc才能使其正常工作?为什么? (更新:我已经弄清楚了这部分，但是在底部还有其他一些问题.)

I need to use a self-compiled version of glibc (2.18), newer than the default one on the system (2.15). I can compile&link a C++ program, but when I try to run it, I get errors about libstdc++.so.6. (C programs seems to work just fine.) Do I need to recompile gcc against the newer glibc for this to work? Why? (Update: I figured this part out, but I have a few other questions at the bottom.)

这是一个示例C ++程序:

Here is a sample C++ program:

#include <iostream>
int main()
{
    std::cout << "ok\n";
    return 0;
}

在此答案之后，我将其编译为:

Following this answer, I compiled it with:

g++ -Wl,--rpath=/path/to/glibc-2.18/lib -Wl,--dynamic-linker=/path/to/glibc-2.18/lib/ld-2.18.so a.cpp

它编译没有错误，然后ldd说:

It compiles with no errors, then ldd says:

$ ldd a.out 
    linux-vdso.so.1 =>  (0x00007fff421fe000)
    libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f3b96e7f000)
    libc.so.6 => /path/to/glibc-2.18/lib/libc.so.6 (0x00007f3b96ad1000)
    libm.so.6 => /path/to/glibc-2.18/lib/libm.so.6 (0x00007f3b967cf000)
    /path/to/glibc-2.18/lib/ld-2.18.so => /lib64/ld-linux-x86-64.so.2 (0x00007f3b9719d000)
    libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f3b965b9000)

但是当我尝试运行它时:

But when I try to run it:

$ ./a.out 
./a.out: error while loading shared libraries: libstdc++.so.6: cannot open shared object file: No such file or directory

这令人困惑，因为看起来ldd发现libstdc++.so.6很好(特定版本为libstdc++.so.6.0.16).

This is confusing because it looks like ldd finds libstdc++.so.6 just fine (the specific version is libstdc++.so.6.0.16).

更新:问题似乎是(不确定)新的2.18动态链接器正在使用其自己的库路径，该路径仅包含/path/to/glibc-2.18/lib的子文件夹.通过添加此新路径，然后是到/path/to/glibc-2.18/etc/ld.so.conf的标准路径(/lib', '/usr/lib等)，然后运行/path/to/glibc-2.18/sbin/ldconfig，可以使程序运行.更多问题:

Update: The problem seems to have been (not sure) that the new 2.18 dynamic linker is using its own library path which includes only subfolders of /path/to/glibc-2.18/lib. I got the program to run by adding this new path, followed by the standard paths (/lib', '/usr/lib, etc) to /path/to/glibc-2.18/etc/ld.so.conf and running /path/to/glibc-2.18/sbin/ldconfig. More questions:

1. 我绝对需要新的2.18动态链接程序来运行带有glibc-2.18的程序吗?标准链接器不能这样做吗? (这将避免我不得不设置并不断更新2.18动态链接器的路径.)

1. Do I absolutely need the new 2.18 dynamic linker to run a program with glibc-2.18? Can't the standard linker do it? (This would avoid me having to set up and continuously update the paths of the 2.18 dynamic linker.)

如果我使用2.18动态链接器进行编译，但没有--rpath，则该程序将无法运行.为什么?

If I compile with the 2.18 dynamic linker but without --rpath, the program doesn't work. Why?

是否应该在编译命令中使用-L/path/to/glibc-2.18/lib(除了--rpath和--dynamic-linker之外)?

Should I be using -L/path/to/glibc-2.18/lib in the compilation command (in addition to --rpath and --dynamic-linker)?

推荐答案

我绝对需要新的2.18动态链接程序来运行带有glibc-2.18的程序吗?

Do I absolutely need the new 2.18 dynamic linker to run a program with glibc-2.18?

是的(差不多，请参见脚注).

Yes (well, almost. See footnote).

这将避免我不得不设置并不断更新2.18动态链接器的路径.

This would avoid me having to set up and continuously update the paths of the 2.18 dynamic linker.

一种常见的技术是创建一个g++外壳包装程序，例如g++glibc2.18，并封装在其中添加必要的链接参数.然后，简单的make CXX=g++glibc2.18会做正确的事.

A common technique is to create a g++ shell wrapper, e.g. g++glibc2.18, and encapsulate adding the necessary link arguments there. Then a simple make CXX=g++glibc2.18 would do the right thing.

标准链接器不能这样做吗?

Can't the standard linker do it?

不.有关说明，请参见此答案.

No. See this answer for explanation.

如果我使用2.18动态链接器但没有--rpath进行编译，则该程序将无法运行.为什么?

If I compile with the 2.18 dynamic linker but without --rpath, the program doesn't work. Why?

看到相同的答案.

是否应该在编译命令中使用-L/path/to/glibc-2.18/lib(除了--rpath和--dynamic-linker之外)?

Should I be using -L/path/to/glibc-2.18/lib in the compilation command (in addition to --rpath and --dynamic-linker)?

是的，如果要使用glibc-2.18中存在但系统库中不存在的符号.否则，不会.

Yes, if you want to use symbols that are present in glibc-2.18 but not present in your system library. Otherwise, no.

脚注:

作为替代方案，您可以在不使用特殊标志的情况下构建程序，然后使用显式加载程序调用"实际运行它:/path/to/glibc-2.18/lib/ld-2.18.so /path/to/a.out.

As an alternative, you could build your program without the special flags, then use "explicit loader invocation" to actually run it: /path/to/glibc-2.18/lib/ld-2.18.so /path/to/a.out.

当心:这并不总是有效:如果程序喜欢重新执行exec本身(以及在其他罕见情况下).以这种方式调用它时，您可能还无法调试它.

Beware: this doesn't always work: if the program likes to re-exec itself (and under other rare conditions). You may also have trouble debugging it when it is invoked that way.

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