/***************************************
* interface to binary semaphore        *
*                                      *
***************************************/

#include <events.h>
#include <stdio.h>
#include <errno.h>
#include <strings.h>

char message[72];

sem_exist(sem_name)
char  *sem_name;
{
   int ev_id;

   if ((ev_id = _ev_link(sem_name)) == -1)
      return 0; /* event does not exist */
   else
      _ev_unlink(ev_id);  /* existing event is unlinked */
   return 1;
}

sem_reset(sem_name)
char  *sem_name;
{
   int ev_id;

   if ((ev_id = _ev_link(sem_name)) == -1)
      return 0; /* event does not exist */
   else
      _ev_set(ev_id, 1, 0);
   return 1;
}

sem_link(sem_name, calling)
char  *sem_name, *calling;
{
   int ev_id;
   char *err_type = ": error linking to event %s , errno %d \n";
     
   /* create or link to the event to share module */
   if ((ev_id = _ev_link(sem_name)) == -1){
      strcpy(message, calling);
      strcat(message, err_type);
      exit(_errmsg(errno, message, sem_name, errno));
   }
   return ev_id;
}

sem_link_cr(sem_name, calling)
char  *sem_name, *calling;
{
   int ev_id;
   char *err_type = ": error getting creating event %s, errno %d\n";
     
   /* create or link to the event to share module */
   if ((ev_id = _ev_link(sem_name)) == -1)
       if ((ev_id = _ev_creat(1, -1, 1, sem_name)) == -1){
           strcpy(message, calling);
           strcat(message, err_type);
           exit(_errmsg(errno, message, sem_name, errno));
       }
   return ev_id;
}


sem_unl(ev_id, calling)
int ev_id;
char *calling;
{
   char *err_unl = ": error unlinking from event , errno %d\n";

   /* unlink from event  */
   if (_ev_unlink(ev_id) == -1){
       strcpy(message, calling);
       strcat(message, err_unl);
       exit(_errmsg(errno, message, errno ));
       }
   return 0;
}

sem_unl_del(ev_id, sem_name, calling)
int ev_id;
char *sem_name, *calling;
{
   char *err_unl = ": error unlinking from event %s, errno %d\n";
   char *err_del = ": error deleting event %s, errno %d \n";

   /* unlink from event  */
   if (_ev_unlink(ev_id) == -1){
       strcpy(message, calling);
       strcat(message, err_unl);
       exit(_errmsg(errno, message, sem_name, errno));
       }

   /* delete event from system if this was the last process to unlink */
   if (_ev_delete(sem_name) == -1 && errno != E_EVBUSY){
       strcpy(message, calling);
       strcat(message, err_del);
       exit(_errmsg(errno, message, sem_name, errno));
       }
   return 0;
}

sem_wait(ev_id, calling)
int ev_id;
char  *calling;
{
   char *err_type = ": error waiting for event , errno %d\n";

   if (_ev_wait(ev_id, 1, 1) == -1){
       strcpy(message, calling);
       strcat(message, err_type);
       exit(_errmsg(errno, message, errno));
       }
   return 0;
}

sem_free(ev_id, calling)
int ev_id;
char  *calling;
{
   char *err_type = ": error signalling event, errno %d \n";


   if (_ev_signal(ev_id, 0) == -1) {
       strcpy(message, calling);
       strcat(message, err_type);
       exit(_errmsg(errno, message, errno));
       }
   return 0;
}