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!)

mysql-test/r/variables.result

@@ -1479,16 +1479,6 @@ SELECT @@GLOBAL.server_id;
 @@GLOBAL.server_id
 0
 SET GLOBAL server_id = @old_server_id;
-SELECT @@GLOBAL.INIT_CONNECT, @@GLOBAL.INIT_CONNECT IS NULL;
-@@GLOBAL.INIT_CONNECT	@@GLOBAL.INIT_CONNECT IS NULL
-	1
-CREATE TABLE t1 (a INT);
-INSERT INTO t1 VALUES ();
-SET @bug42778= @@sql_safe_updates;
-SET @@sql_safe_updates= 0;
-DELETE FROM t1 ORDER BY (@@GLOBAL.INIT_CONNECT) ASC LIMIT 10;
-SET @@sql_safe_updates= @bug42778;
-DROP TABLE t1;
 #
 # BUG#10206 - InnoDB: Transaction requiring Max_BinLog_Cache_size > 4GB always rollsback
 #

mysql-test/t/func_time.test

@@ -883,7 +883,9 @@ SELECT STR_TO_DATE(SPACE(2),'1');
 --echo #
 
 SET GLOBAL SQL_MODE='';
+--disable_warnings
 DO  STR_TO_DATE((''), FROM_DAYS(@@GLOBAL.SQL_MODE));
+--enable_warnings
 SET GLOBAL SQL_MODE=DEFAULT;
 
 --echo #

mysql-test/t/variables.test

@@ -1206,22 +1206,6 @@ SET GLOBAL server_id = -1;
 SELECT @@GLOBAL.server_id;
 SET GLOBAL server_id = @old_server_id;
 
-#
-# Bug #42778: delete order by null global variable causes 
-#             assertion .\filesort.cc, line 797
-#
-
-SELECT @@GLOBAL.INIT_CONNECT, @@GLOBAL.INIT_CONNECT IS NULL;
-
-CREATE TABLE t1 (a INT);
-INSERT INTO t1 VALUES ();
-SET @bug42778= @@sql_safe_updates;
-SET @@sql_safe_updates= 0;
-DELETE FROM t1 ORDER BY (@@GLOBAL.INIT_CONNECT) ASC LIMIT 10;
-SET @@sql_safe_updates= @bug42778;
-
-DROP TABLE t1;
-
 --echo #
 --echo # BUG#10206 - InnoDB: Transaction requiring Max_BinLog_Cache_size > 4GB always rollsback
 --echo #

sql/item_func.cc

@@ -5668,24 +5668,6 @@ enum_field_types Item_func_get_system_var::field_type() const
 }
 
 
-/*
-  Uses var, var_type, component, cache_present, used_query_id, thd,
-  cached_llval, null_value, cached_null_value
-*/
-#define get_sys_var_safe(type) \
-do { \
-  type value; \
-  mysql_mutex_lock(&LOCK_global_system_variables); \
-  value= *(type*) var->value_ptr(thd, var_type, &component); \
-  mysql_mutex_unlock(&LOCK_global_system_variables); \
-  cache_present |= GET_SYS_VAR_CACHE_LONG; \
-  used_query_id= thd->query_id; \
-  cached_llval= null_value ? 0 : (longlong) value; \
-  cached_null_value= null_value; \
-  return cached_llval; \
-} while (0)
-
-
 longlong Item_func_get_system_var::val_int()
 {
   THD *thd= current_thd;
@@ -5719,51 +5701,11 @@ longlong Item_func_get_system_var::val_int()
     }
   }
 
-  switch (var->show_type())
-  {
-    case SHOW_SINT:     get_sys_var_safe (int);
-    case SHOW_SLONG:    get_sys_var_safe (long);
-    case SHOW_SLONGLONG:get_sys_var_safe (longlong);
-    case SHOW_UINT:     get_sys_var_safe (uint);
-    case SHOW_ULONG:    get_sys_var_safe (ulong);
-    case SHOW_ULONGLONG:get_sys_var_safe (ulonglong);
-    case SHOW_HA_ROWS:  get_sys_var_safe (ha_rows);
-    case SHOW_BOOL:     get_sys_var_safe (bool);
-    case SHOW_MY_BOOL:  get_sys_var_safe (my_bool);
-    case SHOW_DOUBLE:
-      {
-        double dval= val_real();
-
+  cached_llval= var->val_int(&null_value, thd, var_type, &component);
+  cache_present |= GET_SYS_VAR_CACHE_LONG;
   used_query_id= thd->query_id;
-        cached_llval= (longlong) dval;
-        cache_present|= GET_SYS_VAR_CACHE_LONG;
-        return cached_llval;
-      }
-    case SHOW_CHAR:
-    case SHOW_CHAR_PTR:
-    case SHOW_LEX_STRING:
-      {
-        String *str_val= val_str(NULL);
-
-        if (str_val && str_val->length())
-          cached_llval= longlong_from_string_with_check (system_charset_info,
-                                                          str_val->c_ptr(), 
-                                                          str_val->c_ptr() + 
-                                                          str_val->length());
-        else
-        {
-          null_value= TRUE;
-          cached_llval= 0;
-        }
-
-        cache_present|= GET_SYS_VAR_CACHE_LONG;
+  cached_null_value= null_value;
   return cached_llval;
-      }
-
-    default:            
-      my_error(ER_VAR_CANT_BE_READ, MYF(0), var->name.str); 
-      return 0;                               // keep the compiler happy
-  }
 }
 
 
@@ -5796,61 +5738,10 @@ String* Item_func_get_system_var::val_str(String* str)
     }
   }
 
-  str= &cached_strval;
-  switch (var->show_type())
-  {
-    case SHOW_CHAR:
-    case SHOW_CHAR_PTR:
-    case SHOW_LEX_STRING:
-    {
-      mysql_mutex_lock(&LOCK_global_system_variables);
-      char *cptr= var->show_type() == SHOW_CHAR ? 
-        (char*) var->value_ptr(thd, var_type, &component) :
-        *(char**) var->value_ptr(thd, var_type, &component);
-      if (cptr)
-      {
-        size_t len= var->show_type() == SHOW_LEX_STRING ?
-          ((LEX_STRING*)(var->value_ptr(thd, var_type, &component)))->length :
-          strlen(cptr);
-        if (str->copy(cptr, len, collation.collation))
-        {
-          null_value= TRUE;
-          str= NULL;
-        }
-      }
-      else
-      {
-        null_value= TRUE;
-        str= NULL;
-      }
-      mysql_mutex_unlock(&LOCK_global_system_variables);
-      break;
-    }
-
-    case SHOW_SINT:
-    case SHOW_SLONG:
-    case SHOW_SLONGLONG:
-    case SHOW_UINT:
-    case SHOW_ULONG:
-    case SHOW_ULONGLONG:
-    case SHOW_HA_ROWS:
-    case SHOW_BOOL:
-    case SHOW_MY_BOOL:
-      str->set (val_int(), collation.collation);
-      break;
-    case SHOW_DOUBLE:
-      str->set_real (val_real(), decimals, collation.collation);
-      break;
-
-    default:
-      my_error(ER_VAR_CANT_BE_READ, MYF(0), var->name.str);
-      str= NULL;
-      break;
-  }
-
+  str= var->val_str(&cached_strval, thd, var_type, &component);
   cache_present|= GET_SYS_VAR_CACHE_STRING;
   used_query_id= thd->query_id;
-  cached_null_value= null_value;
+  cached_null_value= null_value= !str;
   return str;
 }
 
@@ -5888,58 +5779,11 @@ double Item_func_get_system_var::val_real()
     }
   }
 
-  switch (var->show_type())
-  {
-    case SHOW_DOUBLE:
-      mysql_mutex_lock(&LOCK_global_system_variables);
-      cached_dval= *(double*) var->value_ptr(thd, var_type, &component);
-      mysql_mutex_unlock(&LOCK_global_system_variables);
-      used_query_id= thd->query_id;
-      cached_null_value= null_value;
-      if (null_value)
-        cached_dval= 0;
-      cache_present|= GET_SYS_VAR_CACHE_DOUBLE;
-      return cached_dval;
-    case SHOW_CHAR:
-    case SHOW_LEX_STRING:
-    case SHOW_CHAR_PTR:
-      {
-        mysql_mutex_lock(&LOCK_global_system_variables);
-        char *cptr= var->show_type() == SHOW_CHAR ? 
-          (char*) var->value_ptr(thd, var_type, &component) :
-          *(char**) var->value_ptr(thd, var_type, &component);
-        if (cptr)
-          cached_dval= double_from_string_with_check (system_charset_info, 
-                                                cptr, cptr + strlen (cptr));
-        else
-        {
-          null_value= TRUE;
-          cached_dval= 0;
-        }
-        mysql_mutex_unlock(&LOCK_global_system_variables);
+  cached_dval= var->val_real(&null_value, thd, var_type, &component);
+  cache_present |= GET_SYS_VAR_CACHE_DOUBLE;
   used_query_id= thd->query_id;
   cached_null_value= null_value;
-        cache_present|= GET_SYS_VAR_CACHE_DOUBLE;
   return cached_dval;
-      }
-    case SHOW_SINT:
-    case SHOW_SLONG:
-    case SHOW_SLONGLONG:
-    case SHOW_UINT:
-    case SHOW_ULONG:
-    case SHOW_ULONGLONG:
-    case SHOW_HA_ROWS:
-    case SHOW_BOOL:
-    case SHOW_MY_BOOL:
-        cached_dval= (double) val_int();
-        cache_present|= GET_SYS_VAR_CACHE_DOUBLE;
-        used_query_id= thd->query_id;
-        cached_null_value= null_value;
-        return cached_dval;
-    default:
-      my_error(ER_VAR_CANT_BE_READ, MYF(0), var->name.str);
-      return 0;
-  }
 }
 
 

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)

sql/set_var.h

@@ -108,6 +108,10 @@ public:
   bool set_default(THD *thd, enum_var_type type);
   bool update(THD *thd, set_var *var);
 
+  longlong val_int(bool *is_null, THD *thd, enum_var_type type, LEX_STRING *base);
+  String *val_str(String *str, THD *thd, enum_var_type type, LEX_STRING *base);
+  double val_real(bool *is_null, THD *thd, enum_var_type type, LEX_STRING *base);
+
   SHOW_TYPE show_type() { return show_val_type; }
   int scope() const { return flags & SCOPE_MASK; }
   CHARSET_INFO *charset(THD *thd);