Access Function in Shared Library

The following example shows how dlopen() and dlsym() can be used to access either function or data objects. For simplicity, error checking has been omitted.

void    *handle;
int     *iptr, (*fptr)(int);


/* open the needed object */
handle = dlopen("/usr/home/me/libfoo.so", RTLD_LOCAL | RTLD_LAZY);


/* find the address of function and data objects */
*(void **)(&fptr) = dlsym(handle, "my_function");
iptr = (int *)dlsym(handle, "my_object");


/* invoke function, passing value of integer as a parameter */
(*fptr)(*iptr);

http://pubs.opengroup.org/onlinepubs/009695399/functions/dlsym.html