Re: C++, dlopen() and undefined __pure_virtual

["H. J. Lu" <hjl at lucon dot org>]

On Fri, Apr 23, 2004 at 09:24:26PM +0530, Banibrata Dutta wrote:
> hi,
> 
> i have a peculiar scenario. let me explain it briefly, and my
> problem had something to do with demand loading via 
> 
> A  B  C
> ^  ^  ^
> |  |  |
> X  Y  Z
> 
> i.e. A, B and C are 3 base classes and X, Y, Z are their
> concrete implementations. the program's main() uses the interface
> exposed by A, B & C i.e. the virutal functions, to invoke the
> real implementation in X, Y, Z class.
> 
> i have 1 binary (executable) that contains A,B,C amongst other
> things, and a shared object e.g. xyz.so containing X,Y & Z.
> 
> conceptually what i want to do is to: 
> 
>   handle = dlopen("./libxyz.so", RTLD_GLOBAL);
>   createAobjPtr = (A_FNPTR*) dlsym(handle, "createAobj");
>   A *aPtr = (*createAobjPtr)();
> 
> everything goes file and links well. but when i run the executable
> it fails saying (due to my calling dlerror()), that:
> 
>  libxyz.so: undefined symbol: __pure_virtual
> 
> what is happening ?? what is really the cause ??
> 
> i've created the shared object as follows:
> $ ld -shared -soname libxyz.so -o libxyz.so -lc X.o -lc Y.o -lc Z.o -lc A.o
> -lc B.o -lc C.o -lpthread -lm -ldl

Are you running Linux? If yes, use "g++ -shared", not "ld -shared".


H.J.