Function get_one_variable

sql/sql_show.cc:3862–3992

*/

const char* get_one_variable(THD *thd,
                             const SHOW_VAR *variable,
                             enum_var_type value_type, SHOW_TYPE show_type,
                             system_status_var *status_var,
                             const CHARSET_INFO **charset, char *buff,
                             size_t *length)
{
  Any_pointer value, status_var_value;
  value.as_void= variable->value;
  status_var_value.as_system_status_var= status_var;
  const char *pos= buff;
  const char *end= buff;


  if (show_type == SHOW_SYS)
  {
    const sys_var *var= value.as_sys_var;
    show_type= var->show_type();
    value.as_uchar= var->value_ptr(thd, value_type, &null_clex_str);
    *charset= var->charset(thd);
  }

  /*
    note that value may be == buff. All SHOW_xxx code below
    should still work in this case
  */
  switch (show_type) {
  case SHOW_DOUBLE_STATUS:
    value.as_char= status_var_value.as_char + value.as_intptr;
    /* fall through */
  case SHOW_DOUBLE:
    /* 6 is the default precision for '%f' in sprintf() */
    end= buff + my_fcvt(*value.as_double, 6, buff, NULL);
    break;
  case SHOW_LONG_STATUS:
    value.as_char= status_var_value.as_char + value.as_intptr;
    /* fall through */
  case SHOW_ULONG:
  case SHOW_LONG_NOFLUSH: // the difference lies in refresh_status()
#ifndef _WIN64
  case SHOW_SIZE_T:
#endif
    end= int10_to_str(*value.as_long, buff, 10);
    break;
  case SHOW_LONGLONG_STATUS:
    value.as_char= status_var_value.as_char + value.as_intptr;
    /* fall through */
  case SHOW_ULONGLONG:
#ifdef _WIN64
  case SHOW_SIZE_T:
#endif
    end= longlong10_to_str(*value.as_longlong, buff, 10);
    break;
  case SHOW_HA_ROWS:
    end= longlong10_to_str((longlong) *value.as_ha_rows, buff, 10);
    break;
  case SHOW_BOOL:
    end= strmov(buff, *value.as_bool ? "ON" : "OFF");