libgomp and python: dlopen fails

[Sebastian Steiger]

The interesting part of the output when LD_DEBUG=all is this:

     21475:     file=libgomp.so.1 [0];  generating link map
      21475:     symbol=dlerror;  lookup in file=python
      21475:     symbol=dlerror;  lookup in 
file=/usr/lib64/libpython2.3.so.1.0
      21475:     symbol=dlerror;  lookup in file=/lib64/tls/libpthread.so.0
      21475:     symbol=dlerror;  lookup in file=/lib64/libdl.so.2
      21475:     binding file /usr/lib64/libpython2.3.so.1.0 to 
/lib64/libdl.so.2: normal symbol `dlerror' [GLIBC_2.2.5]
      21475:     symbol=__dcgettext;  lookup in file=python
      21475:     symbol=__dcgettext;  lookup in 
file=/usr/lib64/libpython2.3.so.1.0
      21475:     symbol=__dcgettext;  lookup in 
file=/lib64/tls/libpthread.so.0
      21475:     symbol=__dcgettext;  lookup in file=/lib64/libdl.so.2
      21475:     symbol=__dcgettext;  lookup in file=/lib64/libutil.so.1
      21475:     symbol=__dcgettext;  lookup in file=/lib64/tls/libm.so.6
      21475:     symbol=__dcgettext;  lookup in file=/lib64/tls/libc.so.6
      21475:     binding file /lib64/libdl.so.2 to /lib64/tls/libc.so.6: 
normal symbol `__dcgettext' [GLIBC_2.2.5]
      21475:     symbol=__asprintf;  lookup in file=python
      21475:     symbol=__asprintf;  lookup in 
file=/usr/lib64/libpython2.3.so.1.0
      21475:     symbol=__asprintf;  lookup in 
file=/lib64/tls/libpthread.so.0
      21475:     symbol=__asprintf;  lookup in file=/lib64/libdl.so.2

< The rest is just python stuff for error handling and screen output.>



This encouraged me to take a sample C++ file for testing dlopen() which 
I found on the internet:


#include <iostream>
#include <dlfcn.h>
using namespace std;

int main()
{	
     void* handle = dlopen("(...)/libgomp.so.1", RTLD_LAZY);

     if (!handle) {
         cerr << "Cannot open library: " << dlerror() << '\n';
         return 1;
     }
     cout << "Loading was successful. Closing library...\n";
     dlclose(handle);
}



I compiled this file with g++4 -o dlopen_test.bin dlopen_test.cpp -ldl 
(I called the file dlopen_test.cpp) and got the following output:

"Cannot open library: (...)/libgomp.so.1: shared object cannot be 
dlopen()ed"


Obviously the output of the python shell was just dlerror(), but it is 
not very instructive.

I also tried RTLD_NOW instead of RTLD_LAZY, but the error was the same.