DynLib.h

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/*
** This file is part of eOn.
**
** SPDX-License-Identifier: BSD-3-Clause
**
** Copyright (c) 2010--present, eOn Development Team
** All rights reserved.
**
** Repo:
** https://github.com/TheochemUI/eOn
*/
#pragma once

 
#include <string>
 
#ifdef _WIN32
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#else
#include <dlfcn.h>
#endif
 
namespace eonc::dynlib {
 
#ifdef _WIN32
using Handle = HMODULE;
 
inline Handle open(const char *name) noexcept { return LoadLibraryA(name); }
 
inline void *sym(Handle h, const char *name) noexcept {
  return reinterpret_cast<void *>(GetProcAddress(h, name));
}
 
inline void close(Handle h) noexcept {
  if (h)
    FreeLibrary(h);
}
 
inline std::string error() {
  DWORD err = GetLastError();
  if (err == 0)
    return {};
  LPSTR buf = nullptr;
  FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
                     FORMAT_MESSAGE_IGNORE_INSERTS,
                 nullptr, err, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                 reinterpret_cast<LPSTR>(&buf), 0, nullptr);
  std::string msg(buf ? buf : "unknown error");
  if (buf)
    LocalFree(buf);
  return msg;
}
 
#else // POSIX (Linux, macOS)
using Handle = void *;
 
inline Handle open(const char *name) noexcept {
  // RTLD_DEEPBIND (Linux-only): make the library prefer its own symbols over
  // globally-visible ones.  Without this, Fortran helper symbols exported by
  // Fortran shared libraries (e.g. neighbours_ in libeon_sw.so) can be
  // hijacked by identically-named symbols in other loaded libraries (e.g.
  // libxtb.so.6 also exports neighbours_), causing mis-dispatch and SIGSEGV.
#if defined(__linux__)
  return dlopen(name, RTLD_NOW | RTLD_LOCAL | RTLD_DEEPBIND);
#else
  return dlopen(name, RTLD_NOW | RTLD_LOCAL);
#endif
}
 
inline void *sym(Handle h, const char *name) noexcept { return dlsym(h, name); }
 
inline void close(Handle h) noexcept {
  if (h)
    dlclose(h);
}
 
inline std::string error() {
  const char *msg = dlerror();
  return msg ? std::string(msg) : std::string{};
}
#endif

inline Handle openFirst(const char *const names[]) noexcept {
  for (const char *const *name = names; *name; ++name) {
    Handle h = open(*name);
    if (h)
      return h;
  }
  return {};
}

template <typename Fn> Fn loadSym(Handle h, const char *name) noexcept {
  return reinterpret_cast<Fn>(sym(h, name));
}
 
} // namespace eonc::dynlib