Can I change LD_LIBRARY_PATH after program start?

[cheerful]

I would want to dlopen a library, which in turn, depends on some other libraries. I tried to change LD_LIBRARY_PATH in main before calling dlopen but it failed. It appears thath LD_LIBRARY_PATH is read only on start up. Is there any way to inform loader that it has changed?

Thanks!

 

[xwb]

No but you can try an absolute path to dlopen

 

[cheerful]

That won't help since lib a also depends on lib b, which is not in LD_LIBRARY_PATH either.

 

[jstreich]

Hows about just updating your (and your users) LD_LIBRARY_PATH envrioment variable globally? Adding all the libraries you need to load?

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[tdatgod]

Hi,
Why not load Library b first and then load library a using Absolute path names for both opens.

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[cheerful]

No, can't work that way.

lib a requires b, but that is ONLY required by a, nothing else in the program. From the program point of view, b is NOT needed.

 

[jstreich]

So? Linking an unused library doesn't affect the size of the executable much (if at all).

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[/plug]

 

[cheerful]

That is not a solution.

 

[chipperMDW]

External references in the library are resolved using the libraries in that library's dependency list and any other libraries previously opened with the RTLD_GLOBAL flag. If the executable was linked with the flag "-rdynamic", then the global symbols in the executable will also be used to resolve references in a dynamically loaded library.

So if you can [tt]dlopen[/tt] Library B with [tt]RTLD_GLOBAL[/tt], Library A should resolve its references using Library B's symbols.

 

[cheerful]

My problem is:

I DO NOT know I need B. It is lib A that needs B. So I will only attempt to load A, NOT B.

It is possible to hard code B's location when building A. But that defeat the purpose of dynamic libraries.