mrw-cxx/mrw/dynamiclibrary.hpp

/** @file

    $Id$

    $Date$
    $Author$

    @copy © Marc Wäckerlin
    @license LGPL, see file <a href="license.html">COPYING</a>

    $Log$
    Revision 1.1  2005/02/18 15:53:56  marc
    initial release


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*/

#ifndef __MRW_DYNAMICLIBRARY_HPP__
#define __MRW_DYNAMICLIBRARY_HPP__

#include <ltdl.h>
#include <mrw/string.hpp>
#include <mrw/stdext.hpp>
#include <mrw/exception.hpp>

namespace mrw {

  class DynamicLibrary {
    public:
      class failure: public mrw::runtime_error {
        public:
          failure(const std::string& arg) throw(std::bad_exception):
              mrw::runtime_error("DynamicLibrary failure "+arg
                                 +"; ltdl reason: "+
                                 +mrw::ifelse(lt_dlerror(), "<none>")) {
          }
      };
      class Lib {
          Lib() throw(): _lib(0) {}
          Lib(const std::string& lib) throw(std::exception): _lib(0) {
            open(lib);
          }
          ~Lib() throw() {
            try {close();} catch(...) {}
          }
          operator bool() throw() {
            return _lib;
          }
          Lib& open(const std::string& lib) throw(std::exception) {
            close();
            if (!(_lib = lt_dlopenext(lib.c_str())))
              throw failure("cannot open dynamic library "+lib);
            return *this;
          }
          Lib& close() throw(std::exception) {
            if (_lib && lt_dlclose(_lib)!=0)
              throw failure("cannot close dynamic library");
            _lib = 0;
            return *this;
          }
        private:
          friend class DynamicLibrary;
          lt_dlhandle handle() throw(std::exception) {
            if (!_lib)
              throw failure("library not open");
            return _lib;
          }
        private:
          lt_dlhandle _lib;
      };
    public:
      DynamicLibrary() throw(std::exception): _opened(false) {
        if (lt_dlinit()>0)
          throw failure("cannot initialize dynamic library loader");
        _opened = true;
      }
      DynamicLibrary(const std::string& lib) throw(std::exception):
          _opened(false) {
        if (lt_dlinit()>0)
          throw failure("cannot initialize dynamic library loader");
        _opened = true;
        _lib.open(lib);
      }
      ~DynamicLibrary() throw() {
        try {close();} catch (...) {}
        if (_opened) lt_dlexit();
      }
      DynamicLibrary& open(const std::string& lib) throw(std::exception) {
        _lib.open(lib);
        return *this;
      }
      DynamicLibrary& close() throw(std::exception) {
        _lib.close();
        return *this;
      }
      DynamicLibrary& resident() throw(std::exception) {
        if (lt_dlmakeresident(_lib.handle())!=0)
          throw failure("cannot make library resident");
        return *this;
      }
      bool isResident() throw(std::exception) {
        return lt_dlisresident(_lib.handle())==1;
      }
      lt_ptr symbol(const std::string& name) throw(std::exception) {
        lt_ptr sym(lt_dlsym(_lib.handle(), name.c_str()));
        if (!sym)
          throw failure("cannot load dynamic library symbol: "+name);
        return sym;
      }
      /**
          {{"name1", &name1}, {"name2", &name2}, 0}
          */
      DynamicLibrary& preload(const lt_dlsymlist* symbols)
          throw(std::exception) {
        if (lt_dlpreload(symbols)!=0)
          throw failure("error in preloading libraries");
        return *this;
      }
      /**
          {{"name1", &name1}, {"name2", &name2}, 0}
          */
      DynamicLibrary& preloadDefault(const lt_dlsymlist* symbols)
          throw(std::exception) {
        if (lt_dlpreload_default(symbols)!=0)
          throw failure("error in preloading libraries");
        return *this;
      }
      int foreachfile(const char* searchPath,
                      int(*function)(const char*, lt_ptr),
                      lt_ptr data) throw() {
        return lt_dlforeachfile(searchPath, function, data);
      }
      /// @todo enable
//       static void preloadedSymbols(const std::string& lib,
//                                    const lt_dlsymlist symbols[])
//           throw(std::exception) {
//         Lib lib(lt_dlopenext(lib.c_str()));
//         LTDL_SET_PRELOADED_SYMBOLS(symbols);
//       }
      static void addSearchDir(const std::string& dir) throw(std::exception) {
        if (lt_dladdsearchdir(dir.c_str())!=0)
          throw failure("cannot add search dir: "+dir);
      }
      static void insertSearchDir(const std::string& before,
                                  const std::string& dir)
          throw(std::exception) {
        if (lt_dlinsertsearchdir(before.c_str(), dir.c_str())!=0)
          throw failure("cannot add search dir: "+dir);
      }
      /// @todo enable
//       static std::string void setSearchPath(const std::string& dir) throw() {
//         char const * const path(lt_dlgetsearchpath());
//         if (!path)
//           throw failure("cannot get search path");
//         return path;
//       }
    private:
      bool _opened;
      Lib _lib;
  };
  
}

#endif