SignalHandler.h

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// -*- mode: c++; c-basic-offset:4 -*-
 
// This file is part of libdap, A C++ implementation of the OPeNDAP Data
// Access Protocol.
 
// Copyright (c) 2002,2003 OPeNDAP, Inc.
// Author: James Gallagher <jgallagher@opendap.org>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//
// You can contact OPeNDAP, Inc. at PO Box 112, Saunderstown, RI. 02874-0112.
 
#ifndef signal_handler_h
#define signal_handler_h
 
#include <csignal>
#include <vector>
 
#include "EventHandler.h"
#include "InternalErr.h"
 
namespace libdap {
 
typedef void Sigfunc(int); // Plauger, 1992

class SignalHandler {
private:
    // Table of pointers to instances of EventHandlers. Since EventHandler is
    // abstract, the pointers will actually reference instances that are
    // children of EventHandler. NSIG is defined in signal.h but this may be
    // a portability issue. This has to be static because it is used by a
    // static method.
    static std::vector<EventHandler *> d_signal_handlers;
 
    // This array holds the old signal handlers. Once the handler in
    // d_signal_handler[signum] is run, look here to see what the original
    // action was. This is important since libdap++ is often embedded in code
    // that already has a non-default signal handler for things like SIGINT.
    static std::vector<Sigfunc *> d_old_handlers;
 
    // Entry point adapter installed into sigaction(). This must be a static
    // method (or a regular C-function) to conform to sigaction's interface.
    // this is the part of SignalHandler that uses the Adapter pattern.
    static void dispatcher(int signum);
 
    friend class SignalHandlerTest;
 
    friend class HTTPCacheTest;
 
public:
    SignalHandler() = default;
 
    SignalHandler(const SignalHandler &) = delete;
    SignalHandler &operator=(const SignalHandler &) = delete;
    SignalHandler(SignalHandler &&) = delete;
    SignalHandler &operator=(SignalHandler &&) = delete;
 
    static SignalHandler *instance();
 
    virtual ~SignalHandler() = default;
 
    static EventHandler *register_handler(int signum, EventHandler *eh, bool ignore_by_default = false);
 
    static EventHandler *remove_handler(int signum);
};
 
} // namespace libdap
 
#endif // signal_handler_h