#ifndef SIGNAL_H
#define SIGNAL_H

#include <cerrno>       // errno
#include <csignal>      // sigaction, sigemptyset
#include <system_error> // std::system_error

namespace as
{
    class signal
    {
    public:
        typedef void (*handler_t)(int);

        signal(int number, handler_t handler, int flags = 0)
            : signal_number(number), installed(false)
        {
            struct sigaction new_action;
            new_action.sa_handler = handler;
            new_action.sa_flags = flags;
            sigemptyset(&new_action.sa_mask);

            if (sigaction(signal_number, &new_action, &old_action) == -1)
                throw std::system_error(errno, std::generic_category(),
                                        "sigaction install failed");

            installed = true;
        }

        ~signal()
        {
            if (installed)
                sigaction(signal_number, &old_action, nullptr);
        }

        signal(const signal &) = delete;
        signal &operator=(const signal &) = delete;

    private:
        int signal_number;
        struct sigaction old_action;
        bool installed;
    }; // signal

} // namespace as

#endif // SIGNAL_H