// use dynamic loader to lookup function by name and return pointer-to-function
// compile with -rdynamic -ldl -lm
//
// R. Perry, March 2019
//
#include <stdio.h>
#include <dlfcn.h>

#include "lookup.h"

Func lookup( const char *name)
{
  static void *vp = NULL;  char *err;  dlerror(); // clear any existing error

  if( !vp)
  {
    vp = dlopen( NULL, RTLD_LAZY); // open my own executable

    if( !vp) { err = dlerror(); fprintf( stderr, "dlopen: %s\n", err ? err : "unknown error"); return NULL; }
  }

  void *a = dlsym( vp, name);  err = dlerror();

  if( err) { fprintf( stderr, "dlsym: %s\n", err); return NULL; }

  Func f;  *(void **)(&f) = a;  return f; // f = a, with cast to avoid compile warning
}