Problem to change LD_LIBRARY_PATH with setenv()

[kayfire]

Hi,

hope someone can help me with my little problem.
In my C++ program I try to set LD_LIBRARY_PATH by using

setenv("LD_LIBRARY_PATH", (char*) strMyPath.c_str(), 1);

The library is then loaded with:

handle = dlopen (strLibrary.c_str(), RTLD_NOW | RTLD_GLOBAL);

It does not work to load my library, since it does not know the path. It does not even work for the child.

When I set LD_LIBRARY_PATH using:

export LD_LIBRARY_PATH=Mypath (has got the same input as strMyPath) before starting my application, it works fine.

As it seems to me the LD_LIBRARY_PATH is loaded at program startup. Is there a way of setting LD_LIBRARY_PATH or another variable from my C++ application?

Thank you very much in advance.

Bye Kay

[Franklin52]

Hi,

The answer is no.

You can't change this within a program to have effect on that program because the run-time linker is already loaded by the time your program starts.

It should be a potential security problem if a program should be able to change D_LIBRARY_PATH without the user's knowledge at runtime.

Regards

[kayfire]

Thanks for the fast reply!

Any other ideas how I can specify an additional search path for dlopen() at runtime?

The only idea which comes to my mind is using a script, but this would complicate things too much.

Thanks!

[Franklin52]

I think the easiest way is to used a script, but I hope this can give you more ideas:

http://tldp.org/HOWTO/Program-Library-HOWTO/index.html

Regards

[kayfire]

Thanks for your help, but I have solved the problem differently.

As you have pointed out, the LD_LIBRARY_PATH is only loaded at startup of a new process. During runtime any change is ignored!

That is why I have just called execve("path/app", ppArgs, ppEnv), where

char* ppArgs = {"app", (char*) 0};
char* ppEnv = {"LD_LIBRARY_PATH=PATH1:PATH2", (char*) 0};

This kind of way just works fine and is more or less the same solution, but it is using C/C++ to solve it

[Franklin52]

Hi,

Nice solution, I'll make a note of that!

Thanks and best regards