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/* vim:set ts=3 sw=3 sts=3 et: */
#ifndef MOOST_UTILS_HUP_HANDLER_HPP__
#define MOOST_UTILS_HUP_HANDLER_HPP__

#include <csignal>
#include <cstdlib>

#include <boost/function.hpp>

namespace moost { namespace process {


   class hup_handler
   {
   private:
      // A Meyers Singleton (http://bit.ly/EsS4p)
      static hup_handler & get_single_instance()
      {
         static hup_handler hup_handler;
         return hup_handler;
      }

   public:
      typedef boost::function<void ()> handler_t;

      // Set the customer handler.
      static void set(handler_t const & handler)
      {
         hup_handler & hup_handler = hup_handler::get_single_instance();
         hup_handler.handler_ = handler;
         hup_handler.register_handler();
      }

   private:
      handler_t handler_;

      // This is the proxy handler, which calls the custom handler
      static void sighandler(int)
      {
         hup_handler & hup_handler = hup_handler::get_single_instance();

         if(hup_handler.handler_)
         {
            hup_handler.handler_();
         }
      }

      // Register the proxy handler
      struct sigaction sa_;
      void register_handler()
      {
         memset(&sa_, 0, sizeof(sa_));
         sa_.sa_handler = hup_handler::sighandler;

         // These are the signals we'll block whilst the handlers being called
         sigemptyset(&sa_.sa_mask);
         sa_.sa_flags = SIG_BLOCK;
         sigaddset(&sa_.sa_mask, SIGHUP);

         // These are the signals we'll trap and handle
         sigaction(SIGHUP, &sa_, NULL);
      }
   };

}}

#endif // MOOST_UTILS_HUP_HANDLER_HPP__