DynamicLibraryLoader.h

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//* This file is part of the MOOSE framework
//* https://mooseframework.inl.gov
//*
//* All rights reserved, see COPYRIGHT for full restrictions
//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
//*
//* Licensed under LGPL 2.1, please see LICENSE for details
//* https://www.gnu.org/licenses/lgpl-2.1.html

#pragma once

#include "MooseError.h"
#include "libmesh/libmesh_config.h"
#include <string>

#ifdef LIBMESH_HAVE_DLOPEN
#include <dlfcn.h>
#endif

class DynamicLibraryLoader
{
public:
  DynamicLibraryLoader(const std::string & library_file);
  ~DynamicLibraryLoader();

  template <typename T>
  T getFunction(std::string func, bool hard_fail = true);

private:
  void * _handle;

  const std::string _library_file;
};

template <typename T>
T
DynamicLibraryLoader::getFunction(std::string func, bool hard_fail)
{
#ifdef LIBMESH_HAVE_DLOPEN
  // clear error
  dlerror();

  // Snag the function pointers from the library
  void * pointer = dlsym(_handle, func.c_str());

  // Catch errors
  const char * dlsym_error = dlerror();
  if (dlsym_error && hard_fail)
  {
    dlclose(_handle);
    mooseError("DynamicLibraryLoader error: Unable to find symbol '",
               func,
               "' in library '",
               _library_file,
               "'. ",
               std::string(dlsym_error));
  }

  return *reinterpret_cast<T *>(&pointer);
#else
  // this can never be reached as the object instantiation would have already failed
  return nullptr;
#endif
}