/*
 * Copyright (c) 1995, 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.
 */

/*
 * Triptrap test with semaphores. *Much* cleaner! Just one problem is
 * left: how can I model priorities in case of contention?
 */

#include "pg_config.h"
#include "semaphor.h"
#include "trap.h"
#include <sys/wait.h>
#include <stdlib.h>
#include <stdio.h>

#ifdef WITH_DELAY
# define slp usleep(rand() % 100000 + 10000);
#else
# define slp
#endif
# define LOGFILE "./semtt.log";

void trip(semaphor mutex);
void trap(semaphor mutex);
void reaper(int sig);

int
main()
{
  pid_t trip_pid;
  pid_t trap_pid;
  semaphor mutex;

  logfile = LOGFILE;

  if((mutex = SEM_ALLOC(0 /* or IPC_NOWAIT */)) == NULL)
    {
      perror("semtt: can not allocate semaphore");
      exit(1);
    }

  fprintf(stderr, "mutex->buf.sem_num = %hd, mutex->id = %hd",
		 mutex->buf.sem_num, mutex->id);

  ssignal(SIGCHLD,reaper,0);

  trap_pid = getpid();
  trip_pid = fork();

  if(trip_pid < 0)
    {
      perror("fork for trip:");
      exit(1);
    }
  else
    if(trip_pid == 0) trip(mutex); /* child */
  else
    trap(mutex);

  return 0;
}
  
void
trip(semaphor mutex)
{
  openlog("trip", LOG_NDELAY | LOG_PID, LOG_LPR);
  DBG(syslog(LOG_DEBUG,"I am trip and mutex is %d", mutex));

  while(TRUE)
    {
      DBG(syslog(LOG_DEBUG,"waiting ..."));
      slp;
      DBG(syslog(LOG_DEBUG,"claim the line"));
      if(PROBEREN(mutex) == FAIL)
	{
	  syslog(LOG_ERR, "failed to claim the line: %m");
	  continue;
	}
      syslog(LOG_DEBUG, "have the line");
      fprintf(stderr, "*** TRIP ***\n");
      DBG(syslog(LOG_DEBUG,"working ..."));
      slp;
      DBG(syslog(LOG_DEBUG,"release the line"));
      VERHOGEN(mutex);
      SEM_MODE(mutex, IPC_NOWAIT);
    }
}

void
trap(semaphor mutex)
{
  openlog("trap", LOG_NDELAY | LOG_PID, LOG_LPR);
  DBG(syslog(LOG_DEBUG,"I am trap and mutex is %d", mutex));

  while(TRUE)
    {
      DBG(syslog(LOG_DEBUG,"waiting ..."));
      slp;
      DBG(syslog(LOG_DEBUG,"claim the line"));
      if(PROBEREN(mutex) == FAIL)
	{
	  syslog(LOG_ERR, "failed to claim the line: %m");
	  continue;
	}
      syslog(LOG_DEBUG, "have the line");
      fprintf(stderr, "*** TRAP ***\n");
      DBG(syslog(LOG_DEBUG,"working ..."));
      slp;
      DBG(syslog(LOG_DEBUG,"release the line"));
      VERHOGEN(mutex);
    }
}

void
reaper(int sig)
{
  int status;
  pid_t pid;

  DBG(syslog(LOG_DEBUG, "reaper called by signal %d `%s'",
	 sig, sys_siglist[sig]));

  while((pid = wait3(&status, WNOHANG, 0)) > 0)
    {
      if(WIFEXITED(status))
	{
	  DBG(syslog(LOG_DEBUG, "process %d exited with %d",
		     pid, WEXITSTATUS(status)));
	}
      else if(WIFSIGNALED(status))
	{
	  int tsig = WTERMSIG(status);
	  DBG(syslog(LOG_DEBUG, "process %d received signal %d `%s'",
		     pid, tsig, sys_siglist[tsig]));
	}
      else if(WIFSTOPPED(status))
	{
	  int ssig = WSTOPSIG(status);
	  DBG(syslog(LOG_DEBUG, "process %d stopped by signal %d `s'",
		     pid, ssig, sys_siglist[ssig]));
	  kill(pid, SIGCONT);
	}
    }

  exit(2);
}