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SignalHandler.h

//
// SignalHandler.h
//
// $Id: //poco/1.3/Foundation/include/Poco/SignalHandler.h#1 $
//
// Library: Foundation
// Package: Threading
// Module:  SignalHandler
//
// Definition of the SignalHandler class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_SignalHandler_INCLUDED
#define Foundation_SignalHandler_INCLUDED


#include "Poco/Foundation.h"


#if defined(POCO_OS_FAMILY_UNIX)


#include <vector>
#include <setjmp.h>


namespace Poco {


class Foundation_API SignalHandler
      /// This helper class simplifies the handling of POSIX signals.
      ///
      /// The class provides a signal handler (installed with
      /// installHandlers()) that translates certain POSIX
      /// signals (SIGILL, SIGBUS, SIGSEGV, SIGSYS) into 
      /// C++ exceptions.
      ///
      /// Internally, a stack of sigjmp_buf structs is maintained for
      /// each thread. The constructor pushes a new sigjmp_buf onto
      /// the current thread's stack. The destructor pops the sigjmp_buf
      /// from the stack.
      ///
      /// The poco_throw_on_signal macro creates an instance of SignalHandler
      /// on the stack, which results in a new sigjmp_buf being created.
      /// The sigjmp_buf is then set-up with sigsetjmp().
      ///
      /// The handleSignal() method, which is invoked when a signal arrives,
      /// checks if a sigjmp_buf is available for the current thread.
      /// If so, siglongjmp() is used to jump out of the signal handler.
      ///
      /// Typical usage is as follows:
      ///
      ///     try
      ///     {
      ///          poco_throw_on_signal;
      ///          ...
      ///     }
      ///     catch (Poco::SignalException&)
      ///     {
      ///         ...
      ///     }
      ///
      /// The best way to deal with a SignalException is to log as much context
      /// information as possible, to aid in debugging, and then to exit.
{
public:
      SignalHandler();
            /// Creates the SignalHandler.

      ~SignalHandler();
            /// Destroys the SignalHandler.

      sigjmp_buf& jumpBuffer();
            /// Returns the top-most sigjmp_buf for the current thread.

      static void throwSignalException(int sig);
            /// Throws a SignalException with a textual description  
            /// of the given signal as argument. 
      
      static void install();
            /// Installs signal handlers for SIGILL, SIGBUS, SIGSEGV
            /// and SIGSYS.

protected:
      static void handleSignal(int sig);
            /// The actual signal handler.

      struct JumpBuffer
            /// sigjmp_buf cannot be used to instantiate a std::vector,
            /// so we provide a wrapper struct.
      {
            sigjmp_buf buf;
      };
      typedef std::vector<JumpBuffer> JumpBufferVec;

      static JumpBufferVec& jumpBufferVec();
            /// Returns the JumpBufferVec for the current thread.

private:
      static JumpBufferVec _jumpBufferVec;
      
      friend class ThreadImpl;
};


#define poco_throw_on_signal \
      Poco::SignalHandler _poco_signalHandler; \
      int _poco_signal = sigsetjmp(_poco_signalHandler.jumpBuffer(), 1); \
      if (_poco_signal) _poco_signalHandler.throwSignalException(_poco_signal);


} // namespace Poco


#endif // POCO_OS_FAMILY_UNIX


#endif // Foundation_SignalHandler_INCLUDED

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