/*
 * Copyright (c) 1996 Gunther Schadow.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#pragma implementation

#ifdef PROTOGEN 
# include "exception.h"
# include "logfile.h"
#else
# include <stdio.h>
# define ERROS(fmt, args...) { fprintf(stderr, fmt ": " , ## args); \
			       perror(""); exit(1); }
# define LOGDEBUG(fmt, args...) \
  { fprintf(stderr, __PRETTY_FUNCTION__ ": " fmt "\n" , ## args); }
#endif

#include "Signal.h"
#include <unistd.h>
#include <string.h>

class Signal *Signal::_signals[NSIG] =
{
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
#if NSIG > 16
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
#endif
#if NSIG > 32
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
#endif
#if NSIG > 64
# error NSIG exceeds any reasonable value
#endif
};

void Signal::superhandler(int sig)
{
  for(Signal *s = _signals[sig]; s != NULL; s = s->_next)
    {
      if(s->_flags & f_disable)
	return;
      else if(s->_handler != NULL)
	if((*s->_handler)(*s) != 0)
	  return;
    }
  return;
}

Signal::Signal(int sig, handler_t hdl, int flags, int mask)
{
  _signal      = sig;
  _jmp_succ    = NULL;
  _jmp_pred    = NULL;
  _predecessor = NULL;
  _orig_flags  = 0;

  // BEGIN CRITICAL SECTION
  // block the signal for we are going to touch the chain of
  // Signal objects

  // prepare for setting the signal mask
  sigset_t ss, bs;
  sigemptyset(&bs);
  sigaddset(&bs, _signal);
  sigprocmask(SIG_BLOCK, &bs, &ss);

  // get the current sigaction
  struct sigaction sa;
  sigaction(_signal, NULL, &sa);

  // Save the current state of the signal in _orig_flags

  _orig_handler = (handler_t)sa.sa_handler;

  if(_orig_handler == (handler_t)SIG_IGN)
    _orig_flags  |= f_ignore;
  if(sa.sa_flags & SA_RESTART)
    _orig_flags |= f_restart;
  if(sa.sa_flags & SA_NOCLDSTOP)
    _orig_flags |= f_nocldstop;  
  if(sigismember(&ss, _signal))
    _orig_flags |= f_block;

  // set the flags
  _flags = _orig_flags & ~mask | flags;

  // set the handler
  if(hdl == NULL)
    _handler = _orig_handler;
  else
    _handler = hdl;

  // set the new sigaction
  if(_flags & f_ignore)
    sa.sa_handler = (typeof(sa.sa_handler))SIG_IGN;
  if(_handler == default_handler)
    sa.sa_handler = (typeof(sa.sa_handler))SIG_DFL;
  else
    sa.sa_handler = (typeof(sa.sa_handler))superhandler;  
  if(_flags & f_restart)   sa.sa_flags |= SA_RESTART;
  if(_flags & f_nocldstop) sa.sa_flags |= SA_NOCLDSTOP;

  // install the new sigaction
  sigaction(_signal, &sa, NULL);

  // install the new Signal object in the chain
  _next = _signals[_signal];
  _signals[_signal] = this;
  if(_next != NULL)
    _next->_predecessor = this;

  // END CRITICAL SECTION
  // unblock the signal depending on the flags 
  if(! (_flags & f_block))
    sigprocmask(SIG_UNBLOCK, &bs, NULL);
}

Signal::Signal(const Signal &s)
{
  _signal           = s._signal;
  _flags            = s._flags;
  _handler          = s._handler;
  _predecessor      = NULL;

  // BEGIN CRITICAL SECTION
  // block the signal for we are going to touch the chain of
  // Signal objects

  // prepare for setting the signal mask
  sigset_t ss, bs;
  sigemptyset(&bs);
  sigaddset(&bs, _signal);
  sigprocmask(SIG_BLOCK, &bs, &ss);

  // get the current sigaction
  struct sigaction sa;
  sigaction(_signal, NULL, &sa);

  // Save the current state of the signal in _orig_flags

  _orig_handler = (handler_t)sa.sa_handler;

  if(_orig_handler == (handler_t)SIG_IGN)
    _orig_flags  |= f_ignore;
  if(sa.sa_flags & SA_RESTART)
    _orig_flags |= f_restart;
  if(sa.sa_flags & SA_NOCLDSTOP)
    _orig_flags |= f_nocldstop;  
  if(sigismember(&ss, _signal))
    _orig_flags |= f_block;

  // set the new sigaction
  if(_flags & f_ignore)
    sa.sa_handler = (typeof(sa.sa_handler))SIG_IGN;
  if(_handler == default_handler)
    sa.sa_handler = (typeof(sa.sa_handler))SIG_DFL;
  else
    sa.sa_handler = (typeof(sa.sa_handler))superhandler;  
  if(_flags & f_restart)   sa.sa_flags |= SA_RESTART;
  if(_flags & f_nocldstop) sa.sa_flags |= SA_NOCLDSTOP;

  // install the new sigaction
  sigaction(_signal, &sa, NULL);

  // install the new Signal object in the chain
  _next = _signals[_signal];  
  _signals[_signal] = this;
  if(_next != NULL)
    _next->_predecessor = this;

  // install into the longjump chain
  if(_handler == longjmphandler)
    {
      _jmp_pred = NULL;
      if(_jmp_succ != NULL)
	_jmp_succ->_jmp_pred = this;
      _jmp_succ = _jmp_signal[_signal];
    }
  else
    {
      _jmp_succ = NULL;
      _jmp_pred = NULL;
    }

  // END CRITICAL SECTION
  // unblock the signal depending on the flags 
  if(! (_flags & f_block))
    sigprocmask(SIG_UNBLOCK, &bs, NULL);
}

Signal::~Signal()
{
  // BEGIN CRITICAL SECTION
  sigset_t ss, bs;
  sigemptyset(&bs);
  sigprocmask(SIG_BLOCK, &bs, &ss);
  bool block = sigismember(&ss, _signal);
  
  // remove us from the chain of longjmp links
  if(_jmp_succ != NULL)
    _jmp_succ->_jmp_pred = _jmp_pred;
  if(_jmp_pred != NULL)
    _jmp_pred->_jmp_succ = _jmp_succ;
  else
    _jmp_signal[_signal] = _jmp_succ;

  // remove us from the chain of Signal objects
  if(_next != NULL)
    _next->_predecessor = _predecessor;

  if(_predecessor != NULL) // we are in the middle of the chain
    {
      // write our original values to our predecessor
      _predecessor->_next = _next;
      _predecessor->_orig_flags   = _orig_flags;
      _predecessor->_orig_handler = _orig_handler;
    }
  else // i.e. we are the first on the chain
    {
      // restore original settings
      _signals[_signal] = _next;
      struct sigaction sa;
      sigaction(_signal, NULL, &sa);

      if(_orig_flags & f_ignore)
	sa.sa_handler = (typeof(sa.sa_handler))SIG_IGN;
      else
	sa.sa_handler = (typeof(sa.sa_handler))_orig_handler;
      if(_orig_flags & f_restart)   sa.sa_flags |= SA_RESTART;
      if(_orig_flags & f_nocldstop) sa.sa_flags |= SA_NOCLDSTOP;

      sigaction(_signal, &sa, NULL);
      block = _orig_flags & f_block;
    }

  // END CRITICAL SECTION
  // unblock the signal depending on the block value
  if(! block)
    sigprocmask(SIG_UNBLOCK, &bs, NULL);  
}

int Signal::flags(int flags, int mask)
{
  // BEGIN CRITICAL SECTION
  // block the signal for we are going to modify the Signal object

  // prepare for setting the signal mask
  sigset_t ss, bs;
  sigemptyset(&bs);
  sigaddset(&bs, _signal);
  sigprocmask(SIG_BLOCK, &bs, &ss);

  // set the flags
  int old_flags = _flags;
  _flags = _flags & ~mask | flags;

  // set the new sigaction
  struct sigaction sa;
  sigaction(_signal, NULL, &sa);

  if(_flags & f_ignore)
    sa.sa_handler = (typeof(sa.sa_handler))SIG_IGN;
  if(_handler == default_handler)
    sa.sa_handler = (typeof(sa.sa_handler))SIG_DFL;
  else
    sa.sa_handler = (typeof(sa.sa_handler))superhandler;  
  if(_flags & f_restart)   sa.sa_flags |= SA_RESTART;
  if(_flags & f_nocldstop) sa.sa_flags |= SA_NOCLDSTOP;

  // install the new sigaction
  sigaction(_signal, &sa, NULL);

  // END CRITICAL SECTION
  // unblock the signal depending on the flags 
  if(! (_flags & f_block))
    sigprocmask(SIG_UNBLOCK, &bs, NULL);

  return old_flags;
}

Signal::handler_t Signal::handler(handler_t hdl)
// set a handler
{  
  // BEGIN CRITICAL SECTION
  // block the signal for we are going to touch the chain of
  // Signal objects

  // prepare for setting the signal mask
  sigset_t bs;
  sigemptyset(&bs);
  sigaddset(&bs, _signal);
  sigprocmask(SIG_BLOCK, &bs, NULL);

  // remove us from the chain of jump links if necessary
  if(_handler == longjmphandler && hdl != longjmphandler)
    {
      if(_jmp_succ != NULL)
	_jmp_succ->_jmp_pred = _jmp_pred;
      if(_jmp_pred != NULL)
	_jmp_pred->_jmp_succ = _jmp_succ;
      else
	_jmp_signal[_signal] = _jmp_succ;
      
      _jmp_succ = NULL;
      _jmp_pred = NULL;
    }

  // set the handler
  handler_t old_handler = _handler;
  if(hdl == NULL)
    _handler = _orig_handler;
  else
    _handler = hdl;

  // set the new sigaction
  struct sigaction sa;
  sigaction(_signal, NULL, &sa);
  if(_flags & f_ignore)
    sa.sa_handler = (typeof(sa.sa_handler))SIG_IGN;
  if(_handler == default_handler)
    sa.sa_handler = (typeof(sa.sa_handler))SIG_DFL;
  else
    sa.sa_handler = (typeof(sa.sa_handler))superhandler;  

  // install the new sigaction
  sigaction(_signal, &sa, NULL);

  // END CRITICAL SECTION
  // unblock the signal depending on the flags 
  if(! (_flags & f_block))
    sigprocmask(SIG_UNBLOCK, &bs, NULL);

  return old_handler;
}

bool Signal::ispending() const
// is the signal pending?
{
  sigset_t ss;
  sigpending(&ss);
  return sigismember(&ss, _signal);
}

void Signal::discard()
// discard the pending signal
{
  if(ispending())
    {
      ignore();
      obey();
    }
}

/**********************************************************************
 * non local jump stuff
 **********************************************************************/

class Signal *Signal::_jmp_signal[NSIG] =
{
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
#if NSIG > 16
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
#endif
#if NSIG > 32
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
#endif
#if NSIG > 64
# error NSIG exceeds any reasonable value
#endif
};

int Signal::longjmphandler(Signal &s)
// longjmp to the current JmpBuf
{
  longjmp((jmp_buf)&s._jmp_buf, 1);
  return 0; // NO!
}

Signal::JmpBuf &Signal::__jmp_buf()
{
  if(_handler == longjmphandler) // if already in jmp chain
    {
      // log off jmp links
      if(_jmp_succ != NULL)
	_jmp_succ->_jmp_pred = _jmp_pred;
      if(_jmp_pred != NULL)
	_jmp_pred->_jmp_succ = _jmp_succ;
      else
	_jmp_signal[_signal] = _jmp_succ;
    }
  else
    handler(longjmphandler);
      
  _jmp_succ = _jmp_signal[_signal];
  _jmp_signal[_signal] = this;
  _jmp_pred = NULL;
  if(_jmp_succ != NULL)
    _jmp_succ->_jmp_pred = this;

  return _jmp_buf;
}