int len = __snprintf (buf, buflen, _("Unknown error %d"), errnum); if (len < 0) return NULL; buf[len - 1] = '\0'; return buf;
const char *unk = _("Unknown error "); const size_t unklen = strlen (unk); char *p = buf + buflen; *--p = '\0'; p = _itoa (errnum, p, 10, 0); return memcpy (p - unklen, unk, unklen);
_strerror_internal (errnum, buf, buflen)     int errnum;     char *buf;     size_t buflen;{  if (errnum < 0 || errnum > _sys_nerr)    {      int len = __snprintf (buf, buflen, _("Unknown error %d"), errnum);      if (len < 0)	return NULL;      buf[len - 1] = '\0';      return buf;    }  return (char *) _(_sys_errlist[errnum]);}