FIX(overlay): Implement library search list for dlsym(), add "libc.so.6" to it

[davidebeatrici]

glibc 2.34 moved all functionality of various libraries into the main one.
As a result, dlsym() is now exported by libc instead of libdl.

This commit also makes the related code more robust.
We now iterate through a common library name/path list, regardless of the OS.

[davidebeatrici]

@carlocastoldi Could you check whether this fixes #5852, please?

[Krzmbrzl]

Shouldn't we also search in libdl, if the search in libc is not successful? Otherwise, I think we would essentially lose support for older systems wouldn't we?

[carlocastoldi]

This PR indeed fixes #5852 for me!
Congrats! :D

[davidebeatrici]

This PR indeed fixes #5852 for me!
Congrats! :D

Thank you for testing!

Shouldn't we also search in libdl, if the search in libc is not successful? Otherwise, I think we would essentially lose support for older systems wouldn't we?

Indeed, now that we have a library list it's just a matter of adding a line.

Ubuntu 22.04 (glibc 2.35):

$ readelf -Ws --dyn-syms /lib/x86_64-linux-gnu/libc.so.6 | grep dlsym
   793: 00000000000907c0   206 FUNC    GLOBAL DEFAULT   15 dlsym@@GLIBC_2.34
   795: 00000000000907c0   206 FUNC    GLOBAL DEFAULT   15 dlsym@GLIBC_2.2.5

Ubuntu 20.04 (glibc 2.31):

$ readelf -Ws --dyn-syms /lib/x86_64-linux-gnu/libc.so.6 | grep dlsym
  2155: 000000000015f980   249 FUNC    GLOBAL DEFAULT   15 __libc_dlsym@@GLIBC_PRIVATE

Ubuntu 18.04 (glibc 2.27):

$ readelf -Ws --dyn-syms /lib/x86_64-linux-gnu/libc.so.6 | grep dlsym
  2123: 00000000001663b0   214 FUNC    GLOBAL DEFAULT   13 __libc_dlsym@@GLIBC_PRIVATE

[Krzmbrzl]

Theoretically, having the refactoring and the actual fix in separate commits would be desirable, but not sure if worth the effort in this case...

[davidebeatrici]

I thought about that, but hiding whitespace changes shows a clear diff:

[carlocastoldi]

Dunno if this is related (as without this patch overlay doesn't work at all), but on GNOME 43 if I change desktop or the game minimizes, I get strange purple artefacts.

Changing resolution temporary fixes it

[davidebeatrici]

Does it happen if you switch to borderless windowed mode too?

[carlocastoldi]

Yes, it happens in fullscreen and windowed version. I no don't know how to run the game in borderless window, tho

[davidebeatrici]

-sw -noborder

[carlocastoldi]

It doesn't happen with -sw -noborder. Weirdly enough:

• it doesn't happen if I switch to full screen after launching the game in borderless windowed mode
• it does happen if I switch to borderless windowed mode after launching the game in full screen

[carlocastoldi]

what is stopping this from being merged?