SharedLibrary.h

Go to the documentation of this file.

// @(#)root/reflex:$Id: SharedLibrary.h 29288 2009-07-01 13:03:35Z axel $
// Author: Stefan Roiser 2006

// Copyright CERN, CH-1211 Geneva 23, 2004-2006, All rights reserved.
//
// Permission to use, copy, modify, and distribute this software for any
// purpose is hereby granted without fee, provided that this copyright and
// permissions notice appear in all copies and derivatives.
//
// This software is provided "as is" without express or implied warranty.

#ifndef Reflex_SharedLibrary
#define Reflex_SharedLibrary

// Include files
#ifdef _WIN32
# include <windows.h>
#else
# include <dlfcn.h>
# include <errno.h>
#endif


namespace Reflex {
/**
 * @class SharedLibrary SharedLibrary.h Reflex/SharedLibrary.h
 * @author Stefan Roiser
 * @date 24/11/2006
 * @ingroup Ref
 * Parts of this implementation are copyied from SEAL (http://cern.ch/seal)
 */
class SharedLibrary {
public:
   SharedLibrary(const std::string& libname);

   bool Load();

   bool Unload();

   bool Symbol(const std::string& symname,
               void*& sym);

   const std::string Error();

private:
   /** a handle to the loaded library */
#ifdef _WIN32
   HMODULE fHandle;
#else
   void* fHandle;
#endif
   /** the name of the shared library to handle */
   std::string fLibName;
};

} // namespace Reflex


//-------------------------------------------------------------------------------
inline Reflex::SharedLibrary::SharedLibrary(const std::string& libname):
//-------------------------------------------------------------------------------
   fHandle(0),
   fLibName(libname) {
}


//-------------------------------------------------------------------------------
inline const std::string
Reflex::SharedLibrary::Error() {
//-------------------------------------------------------------------------------
   std::string errString = "";
#ifdef _WIN32
   int error = ::GetLastError();
   LPVOID lpMessageBuffer;
   ::FormatMessage(
      FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
      NULL,
      error,
      MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), //The user default language
      (LPTSTR) &lpMessageBuffer,
      0,
      NULL);
   errString = (const char*) lpMessageBuffer;
   // Free the buffer allocated by the system
   ::LocalFree(lpMessageBuffer);
#else
   errString = std::string(dlerror());
#endif
   return errString;
} // Error


//-------------------------------------------------------------------------------
inline bool
Reflex::SharedLibrary::Load() {
//-------------------------------------------------------------------------------

#ifdef _WIN32
   ::SetErrorMode(0);
   fHandle = ::LoadLibrary(fLibName.c_str());
#else
   fHandle = ::dlopen(fLibName.c_str(), RTLD_LAZY | RTLD_GLOBAL);
#endif

   if (!fHandle) {
      return false;
   } else { return true; }
}


//-------------------------------------------------------------------------------
inline bool
Reflex::SharedLibrary::Symbol(const std::string& symname,
                              void*& sym) {
//-------------------------------------------------------------------------------

   if (fHandle) {
#ifdef _WIN32
      sym = GetProcAddress(fHandle, symname.c_str());
#else
      sym = dlsym(fHandle, symname.c_str());
#endif

      if (sym) {
         return true;
      }
   }
   return false;
}


//-------------------------------------------------------------------------------
inline bool
Reflex::SharedLibrary::Unload() {
//-------------------------------------------------------------------------------

#ifdef _WIN32

   if (FreeLibrary(fHandle) == 0) {
      return false;
   }
#else

   if (dlclose(fHandle) == -1) {
      return false;
   }
#endif
   else { return true; }
}


#endif // Reflex_SharedLibrary

---