如何避开“多个定义的符号”在与gcc链接 [英] How to get around "multiple defined symbols" in linking with gcc

问题描述

我使用的是具有gcc 2.95.3的旧系统，我必须链接两个对象，尽管它们之间没有任何关系，但它们都有相似的命名方法。我不能重命名其中的任何一个，但我希望有一种方法可以构建它们，以免连接器发生抱怨。它所抱怨的方法都是由对象内部的类在内部调用的。我可以做什么？

I am using an older system that has gcc 2.95.3, I have to link in two objects that although they have nothing to do with each other, they each have similarly named methods. I can't rename either of them, but I would hope there is a way to build them as to not have the linker complain. The methods it is complaining about are each internally called by classes within the object. What can I do?

推荐答案

如果你有一个完整的GNU工具链，你应该可以解决你的问题，使用 objcopy ，像这样（如果我已经正确理解你的问题）：

If you have a complete GNU toolchain, you should be able to work around your problem using objcopy, like this (if I've understood your problem correctly):

这里有两个非常相似的对象，foo 和bar，它们都会导出一个名为冲突的符号 - 它在内部使用，但根本不需要导出：

Here are two very similar objects, "foo" and "bar", both of which export a symbol called clash - which is used internally, but doesn't really need to be exported at all:

$ cat foo.c
#include <stdio.h>
void clash(char *s) { printf("foo: %s\n", s); }
void foo(char *s) { clash(s); }
$ 

和

$ cat bar.c
#include <stdio.h>
void clash(char *s) { printf("bar: %s\n", s); }
void bar(char *s) { clash(s); }
$ 

以下是主代码，它们都使用这两个代码：

And here's the main code, which wants to use both:

$ cat main.c
extern void foo(char *s);
extern void bar(char *s);

int main(void)
{
    foo("Hello");
    bar("world");
    return 0;
}
$ 

将它们连接在一起不起作用：

Linking them together doesn't work:

$ gcc -Wall -c foo.c  
$ gcc -Wall -c bar.c
$ gcc -Wall -c main.c
$ gcc -o test main.o foo.o bar.o
bar.o: In function `clash':
bar.c:(.text+0x0): multiple definition of `clash'
foo.o:foo.c:(.text+0x0): first defined here
collect2: ld returned 1 exit status
$ 

因此，使用 objcopy 来改变<$

So, use objcopy to change the visibility of clash in one (or both, if you like!) of the objects:

$ objcopy --localize-symbol=clash bar.o bar2.o
$ 

现在，您可以成功地与修改的对象链接 - 并且该程序的行为应该如此：

Now you can link successfully with the modified object - and the program behaves as it should:

$ gcc -o test main.o foo.o bar2.o
$ ./test
foo: Hello
bar: world
$ 

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