text: /* ISC license. */
  
  #include <errno.h>
  #include <skalibs/error.h>
  #include <skalibs/gensetdyn.h>
  #include <s6/lock.h>
  
  int s6lock_check (s6lock_t *a, uint16_t id)
  {
    unsigned char *p = GENSETDYN_P(unsigned char, &a->data, id) ;
    switch (*p)
    {
      case EBUSY : return 1 ;
      case EINVAL : return (errno = EINVAL, -1) ;
      default :
      {
        if (error_isagain(*p)) return 0 ;
        errno = *p ;
        *p = EINVAL ;
        gensetdyn_delete(&a->data, id) ;
        return -1 ;
      }
    }
  }
  