create sys_var::val_str(), sys_var::val_int(), sys_var::val_real().

Change Item_func_get_system_var::val_xxx functions to use that.

mysql-test/t/variables.test:
  @@GLOBAL.INIT_CONNECT is never NULL anymore. Nor it ever was.
  It was a bug that empty string system variables appeared as NULL
  in the *integer context* (but not in a string, real, or decimal context!)

1 files changed, 109 insertions, 2 deletions

diff --git a/sql/set_var.cc b/sql/set_var.cc
index 2d3e0b7fec4..48f7cc7a054 100644
--- a/sql/set_var.cc
+++ b/sql/set_var.cc
@@ -257,8 +257,7 @@ uchar *sys_var::value_ptr(THD *thd, enum_var_type type, LEX_STRING *base)
 
 bool sys_var::set_default(THD *thd, enum_var_type type)
 {
-  LEX_STRING empty={0,0};
-  set_var var(type, this, &empty, 0);
+  set_var var(type, this, &null_lex_str, 0);
 
   if (type == OPT_GLOBAL || scope() == GLOBAL)
     global_save_default(thd, &var);
@@ -268,6 +267,114 @@ bool sys_var::set_default(THD *thd, enum_var_type type)
   return check(thd, &var) || update(thd, &var);
 }
 
+
+#define do_num_val(T,CMD)                               \
+do {                                                    \
+  mysql_mutex_lock(&LOCK_global_system_variables);      \
+  T val= *(T*) value_ptr(thd, type,  base);             \
+  mysql_mutex_unlock(&LOCK_global_system_variables);    \
+  CMD;                                                  \
+} while (0)
+
+#define case_for_integers(CMD)                      \
+    case SHOW_SINT:     do_num_val (int,CMD);       \
+    case SHOW_SLONG:    do_num_val (long,CMD);      \
+    case SHOW_SLONGLONG:do_num_val (longlong,CMD);  \
+    case SHOW_UINT:     do_num_val (uint,CMD);      \
+    case SHOW_ULONG:    do_num_val (ulong,CMD);     \
+    case SHOW_ULONGLONG:do_num_val (ulonglong,CMD); \
+    case SHOW_HA_ROWS:  do_num_val (ha_rows,CMD);   \
+    case SHOW_BOOL:     do_num_val (bool,CMD);      \
+    case SHOW_MY_BOOL:  do_num_val (my_bool,CMD)
+
+#define case_for_double(CMD)                            \
+    case SHOW_DOUBLE:   do_num_val (double,CMD)
+
+#define case_get_string_as_lex_string                   \
+    case SHOW_CHAR:                                     \
+      mysql_mutex_lock(&LOCK_global_system_variables);  \
+      sval.str= (char*) value_ptr(thd, type, base);     \
+      sval.length= sval.str ? strlen(sval.str) : 0;     \
+      break;                                            \
+    case SHOW_CHAR_PTR:                                 \
+      mysql_mutex_lock(&LOCK_global_system_variables);  \
+      sval.str= *(char**) value_ptr(thd, type, base);   \
+      sval.length= sval.str ? strlen(sval.str) : 0;     \
+      break;                                            \
+    case SHOW_LEX_STRING:                               \
+      mysql_mutex_lock(&LOCK_global_system_variables);  \
+      sval= *(LEX_STRING *) value_ptr(thd, type, base); \
+      break
+
+longlong sys_var::val_int(bool *is_null,
+                          THD *thd, enum_var_type type, LEX_STRING *base)
+{
+  LEX_STRING sval;
+  *is_null= false;
+  switch (show_type())
+  {
+    case_get_string_as_lex_string;
+    case_for_integers(return val);
+    case_for_double(return val);
+    default:            
+      my_error(ER_VAR_CANT_BE_READ, MYF(0), name.str); 
+      return 0;
+  }
+
+  longlong ret= 0;
+  if (!(*is_null= !sval.str))
+    ret= longlong_from_string_with_check(system_charset_info,
+                                         sval.str, sval.str + sval.length);
+  mysql_mutex_unlock(&LOCK_global_system_variables);
+  return ret;
+}
+
+
+String *sys_var::val_str(String *str,
+                         THD *thd, enum_var_type type, LEX_STRING *base)
+{
+  LEX_STRING sval;
+  switch (show_type())
+  {
+    case_get_string_as_lex_string;
+    case_for_integers(return str->set((ulonglong)val, system_charset_info) ? 0 : str);
+    case_for_double(return str->set_real(val, 6, system_charset_info) ? 0 : str);
+    default:
+      my_error(ER_VAR_CANT_BE_READ, MYF(0), name.str);
+      return 0;
+  }
+
+  if (!sval.str || str->copy(sval.str, sval.length, system_charset_info))
+    str= NULL;
+  mysql_mutex_unlock(&LOCK_global_system_variables);
+  return str;
+}
+
+
+double sys_var::val_real(bool *is_null,
+                         THD *thd, enum_var_type type, LEX_STRING *base)
+{
+  LEX_STRING sval;
+  *is_null= false;
+  switch (show_type())
+  {
+    case_get_string_as_lex_string;
+    case_for_integers(return val);
+    case_for_double(return val);
+    default:            
+      my_error(ER_VAR_CANT_BE_READ, MYF(0), name.str); 
+      return 0;
+  }
+
+  double ret= 0;
+  if (!(*is_null= !sval.str))
+    ret= double_from_string_with_check(system_charset_info,
+                                       sval.str, sval.str + sval.length);
+  mysql_mutex_unlock(&LOCK_global_system_variables);
+  return ret;
+}
+
+
 void sys_var::do_deprecated_warning(THD *thd)
 {
   if (deprecation_substitute != NULL)