/*
 * Illustrate the waiting for a semaphore to be set
 * New File Mar 23,1989
 * Author   Jerry LeVan
 *
 */
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <errno.h>

#define COUNT	1		/* How many we are going to create */
#define PERM	0666	/* all can read write */
#define KEY		'JHL '	/* our key */

main()
{
  int id;
  int result;
  struct sembuf {
	short sem_num;
	short sem_op;
	short sem_flag;
  } op[1];

  id = semget(KEY,1,IPC_CREAT|PERM);
  printf("status of get key = %d\n",id);
  if(id == -1) {perror("Bad Semaphore ID fetch"); exit();}

  /* initialize the op data structure */
  op[0].sem_num = 0;		/* the first one */
  op[0].sem_op = -1;		/* wait until we can add 1 */
  op[0].sem_flag = 0;		/* no options */

  /* now try to get past the semaphore */
  printf("Ready to test semaphore\n");
  result = semop(id,op,1);
  if(result == -1){ perror("Bad Wait"); exit();}
  printf("Got past semaphore\n");

 }