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cargumentsdlsym

Passing arguments to Shared Function - C

I have used dlopen to load an object and dlsym to get a function pointer to a shared object function. Everything works fine. I have tested it calling then the shared function which (for now) only prints and it works-prints fine in the main program calling it. Now I want to pass two arguments to this function. An int and a char * .Can anyone help me understand how can I pass arguments to a shared function? I have searched in the web but I cannot understand how it works.

Solution

  • Load the function:

    int (*func)(int x, char *y) = dlsym(dl_handle, "your_function");

    You might well decide you need a cast on the return from dlsym(); it is one of the uglinesses with dynamically loaded libraries.

    Invoke it:

    int i = 37;
char buffer[64];
int result1 = (*func)(i, buffer);  // Old school — pre-C89 (but still works and is explicit)
int result2 = func(i+1, buffer);   // New school — can leave you looking for the wrong thing.