Is there any hope of running dlopen(NULL, ...) and getting symbols for a statically compiled binary?
No.
On most UNIXes you can't even link with -static
and -ldl
at the same time. Using glibc you can, but the utility of doing so is very limited. Basically, this ability is present only to support /etc/nsswitch.conf, and nothing else.
There is also no point in doing the dynamic lookup you did.
If you are trying to allow one of foo
, bar
or baz
be called depending on command line arguments, just put a table in, e.g.
struct { const char *fname, void (*fn)(void) } table[] =
{ {"foo", &foo}, {"bar", &bar}, ...};
for (int i = 0; i < ...; ++i)
if (strcmp(argv[1], table[i].fname) == 0)
// found the entry, call it
(*table[i].fn)();
If you are trying to "maybe" call foo
if it is linked in, and do nothing otherwise, then use weak references:
extern void foo(void) __attribute((weak));
if (&foo != 0) {
// foo was linked in, call it
foo();
}