How to catch exception thrown from library in GCC C++?

Question

When i use dlopen to dynamically load a library it seems i can not catch exceptions thrown by that library. As i understand it it's because dlopen is a C function.

Is there another way to dynamically load a library that makes it possible to catch exceptions thrown by the lib in GCC?

In Windows you can use LoadLibrary but for Linux i have only found dlopen but when using dlopen i can not catch exceptions.

Edit: I have tried void* handle = dlopen("myLib.so", RTLD_NOW | RTLD_GLOBAL); and I still cant catch exceptions thrown by myLib.so

Edit 2: I throw custom exceptions with its own namespace. I want to be able to catch these exceptions outside the library. I want to be able to compile on different compilers, for example GCC 3.2 and GCC 4.1.

In myLib2.so i throw exceptions, one example:

namespace MyNamespace {  
    void MyClass::function1() throw(Exception1) {  
        throw Exception1("Error message");  
    } 
}

In myLib1.so I want to catch that exception:

std::auto_ptr <MyNamespace::MyClass> obj = MyNamespace::getClass();
try {  
    obj->function1();  
} catch (MyNamespace::Exception1& e) {  
    std::cout << e.what();  //This is not caught for some reason.  
}

mylib1.so dynamically loads myLib2.so with:

void* handle = dlopen("myLib2.so", RTLDNOW | RTLDGLOBAL);

This works in Windows (to catch my exceptions) but there I dont use dlopen of course.

Edit 3: myLib1.so is dynamically linked.

Answer 1

You need to specify RTLD_GLOBAL flag to dlopen. This will allow correct weak symbol binding, so each typeinfo symbol for exception object will point at the same place, which is needed by exception processing ABI code.