CODEWITHSUNDEEP
linuxgcclinkerldlinker-scripts
sirgeorge
sirgeorge

Reputation: 6531

How to force linking of a symbol from a particular library?

When linking an executable on Linux i get an 'undefined reference' error like this:

undefined reference to `symbol@SOMELIB_1.0'

I do not have a control of 'SOMELIB', but I do have the symbol symbol in one of my own shared libraries. I'm absolutely sure that the symbol@SOMELIB_1.0 is the same (provides exactly the same functionality) that the symbol in my library, actually even the source code is almost the same.

How to force/alias the symbol@SOMELIB_1.0 to be linked from my library, not from SOMELIB_1.0 ? I was thinking about some kind of symbol versioning tricks in linker script, but I could not find any solution or even clues.

Thanks in advance.

Upvotes: 1

Views: 941

Answers (1)

sirgeorge
sirgeorge

Reputation: 6531

After loooong fight (and search) I found a solution here. To summarize: I needed two symbols. In my source code I put something like this:

__asm__(".symver symbol1, symbol1@SOMELIB_1.0");
void symbol1(void)
{
.....
}

__asm__(".symver symbol2, symbol2@SOMELIB_1.0");
void symbol2(void)
{
.....
}

Then I needed a liker script mylib.map containing:

SOMELIB_1.0 {
    symbol1;
    symbol2;
};

To link "mylib.so" I needed to pass additional argument: -Wl,--version-script=mylib.map

Upvotes: 1

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