if (th->th_unique == NULL) return TD_BADKEY;
td_thr_tsd (const td_thrhandle_t *th, const thread_key_t tk, void **data){  struct _pthread_descr_struct pds;  struct pthread_key_struct *keys = th->th_ta_p->keys;  struct pthread_key_struct key;  int pthread_keys_max = th->th_ta_p->pthread_keys_max;  int pthread_key_2ndlevel_size = th->th_ta_p->pthread_key_2ndlevel_size;  unsigned int idx1st;  unsigned int idx2nd;  void *p;  LOG ("td_thr_tsd");  /* Get the thread descriptor.  */  if (ps_pdread (th->th_ta_p->ph, th->th_unique, &pds,		 sizeof (struct _pthread_descr_struct)) != PS_OK)    return TD_ERR;	/* XXX Other error value?  */  /* Check correct value of key.  */  if (tk >= pthread_keys_max)    return TD_BADKEY;  /* Get the key entry.  */  if (ps_pdread (th->th_ta_p->ph, keys, &key,		 sizeof (struct pthread_key_struct)) != PS_OK)    return TD_ERR;	/* XXX Other error value?  */  /* Fail if this key is not at all used.  */  if (! key.in_use)    return TD_BADKEY;  /* Compute the indeces.  */  idx1st = tk / pthread_key_2ndlevel_size;  idx2nd = tk % pthread_key_2ndlevel_size;  /* Check the pointer to the second level array.  */  if (pds.p_specific[idx1st] == NULL)    return TD_NOTSD;  /* Now get the real key.     XXX I don't know whether it's correct but there is currently no     easy way to determine whether a key was never set or the value     is NULL.  We return an error whenever the value is NULL.  */  if (ps_pdread (th->th_ta_p->ph, &pds.p_specific[idx1st][idx2nd], &p,		 sizeof (void *)) != PS_OK)    return TD_ERR;  if (p != NULL)    *data = p;  return p != NULL ? TD_OK : TD_NOTSD;}