// Copyright (c) 2009 Dmitry Goncharov
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#ifndef BOOST_ASIO_POSIX_SIGNALFD_HPP
#define BOOST_ASIO_POSIX_SIGNALFD_HPP

#if (!defined(BOOST_WINDOWS) && !defined(__CYGWIN__)) \
    || defined(GENERATING_DOCUMENTATION)

#include <signal.h>
#include <unistd.h>

#include <cerrno>
#include <boost/system/system_error.hpp>
#include <boost/throw_exception.hpp>
#include <boost/asio/error.hpp>

namespace boost { namespace asio { namespace posix {

template <int Signo>
class signalfd
{
public:
    typedef char buf_type;

    signalfd()
    {
        int s = pipe(m_pipe);
        if (s < 0)
        {
      	    boost::system::error_code const ec(errno, boost::asio::error::get_system_category());
            boost::system::system_error const e(ec, "pipe");
            boost::throw_exception(e);
        }
        struct sigaction act;
        std::memset(&act, 0, sizeof act);
        std::memset(&m_oldact, 0, sizeof m_oldact);
        act.sa_handler = signalfd<Signo>::on_signal;

        s = sigaction(Signo, &act, &m_oldact);
        if (s < 0)
        {
      	    boost::system::error_code const ec(errno, boost::asio::error::get_system_category());
            boost::system::system_error const e(ec, "sigaction");		
            boost::throw_exception(e);
        }
    }

    ~signalfd()
    {
        sigaction(Signo, &m_oldact, 0);
        close(m_pipe[0]);
        close(m_pipe[1]);
    }

    int fd() const
    {
        return m_pipe[0];
    }

private:
    signalfd(signalfd const&);
    signalfd const& operator=(signalfd const&);

private:
    static void on_signal(int signo)
    {
        try
        {
            buf_type const c = 0;
            // The return value is ignored, because
            // if write() fails there is, probably, nothing useful that can be done.
            while (write(m_pipe[1], &c, sizeof c) < 0 && EINTR == errno);
        }
        catch (...) {}
    }
    static int m_pipe[2];

private:
    struct sigaction m_oldact;
};

template<int Signo>
int signalfd<Signo>::m_pipe[2];

}}}

#endif // (!defined(BOOST_WINDOWS) && !defined(__CYGWIN__)) \
       //     || defined(GENERATING_DOCUMENTATION)
#endif // BOOST_ASIO_POSIX_SIGNALFD_HPP