Manual merge of fixes for bugs #7899 "CREATE TABLE .. SELECT .. and

CONVERT_TZ() function does not work well together" and bug #7705 
"CONVERT_TZ() crashes with subquery/WHERE on index column" in 5.0
tree.

mysql-test/r/timezone2.result

@@ -305,3 +305,11 @@ delete from mysql.db where user like 'mysqltest\_%';
 delete from mysql.tables_priv where user like 'mysqltest\_%';
 flush privileges;
 drop table t1, t2;
+select convert_tz('2005-01-14 17:00:00', 'UTC', custTimeZone) from (select 'UTC' as custTimeZone) as tmp;
+convert_tz('2005-01-14 17:00:00', 'UTC', custTimeZone)
+2005-01-14 17:00:00
+create table t1 select convert_tz(NULL, NULL, NULL);
+select * from t1;
+convert_tz(NULL, NULL, NULL)
+NULL
+drop table t1;

mysql-test/t/timezone2.test

@@ -266,3 +266,20 @@ delete from mysql.db where user like 'mysqltest\_%';
 delete from mysql.tables_priv where user like 'mysqltest\_%';
 flush privileges;
 drop table t1, t2;
+
+#
+# Test for bug #7705 "CONVERT_TZ() crashes with subquery/WHERE on index 
+# column". Queries in which one of time zone arguments of CONVERT_TZ() is
+# determined as constant only at val() stage (not at fix_fields() stage),
+# should not crash server.
+#
+select convert_tz('2005-01-14 17:00:00', 'UTC', custTimeZone) from (select 'UTC' as custTimeZone) as tmp;
+
+#
+# Test for bug #7899 "CREATE TABLE .. SELECT .. and CONVERT_TZ() function
+# does not work well together". The following statement should return only
+# one NULL row and not result of full join.
+#
+create table t1 select convert_tz(NULL, NULL, NULL);
+select * from t1;
+drop table t1;

sql/item_timefunc.cc

@@ -1662,6 +1662,7 @@ void Item_func_convert_tz::fix_length_and_dec()
   collation.set(&my_charset_bin);
   decimals= 0;
   max_length= MAX_DATETIME_WIDTH*MY_CHARSET_BIN_MB_MAXLEN;
+  maybe_null= 1;
 }
 
 
@@ -1674,12 +1675,6 @@ Item_func_convert_tz::fix_fields(THD *thd_arg, TABLE_LIST *tables_arg, Item **re
 
   tz_tables= thd_arg->lex->time_zone_tables_used;
 
-  if (args[1]->const_item())
-    from_tz= my_tz_find(args[1]->val_str(&str), tz_tables);
-
-  if (args[2]->const_item())
-    to_tz= my_tz_find(args[2]->val_str(&str), tz_tables);
-
   return FALSE;
 }
 
@@ -1719,13 +1714,19 @@ bool Item_func_convert_tz::get_date(TIME *ltime,
   my_time_t my_time_tmp;
   bool not_used;
   String str;
-  
-  if (!args[1]->const_item())
+
+  if (!from_tz_cached)
+  {
     from_tz= my_tz_find(args[1]->val_str(&str), tz_tables);
-  
-  if (!args[2]->const_item())
+    from_tz_cached= args[1]->const_item();
+  }
+
+  if (!to_tz_cached)
+  {
     to_tz= my_tz_find(args[2]->val_str(&str), tz_tables);
-  
+    to_tz_cached= args[2]->const_item();
+  }
+
   if (from_tz==0 || to_tz==0 || get_arg0_date(ltime, TIME_NO_ZERO_DATE))
   {
     null_value= 1;
@@ -1747,6 +1748,13 @@ bool Item_func_convert_tz::get_date(TIME *ltime,
 }
 
 
+void Item_func_convert_tz::cleanup()
+{
+  from_tz_cached= to_tz_cached= 0;
+  Item_date_func::cleanup();
+}
+
+
 void Item_date_add_interval::fix_length_and_dec()
 {
   enum_field_types arg0_field_type;

sql/item_timefunc.h

@@ -545,12 +545,15 @@ class Item_func_convert_tz :public Item_date_func
   TABLE_LIST *tz_tables;
   /*
     If time zone parameters are constants we are caching objects that
-    represent them.
+    represent them (we use separate from_tz_cached/to_tz_cached members
+    to indicate this fact, since NULL is legal value for from_tz/to_tz
+    members.
   */
+  bool from_tz_cached, to_tz_cached;
   Time_zone *from_tz, *to_tz;
  public:
   Item_func_convert_tz(Item *a, Item *b, Item *c):
-    Item_date_func(a, b, c) {}
+    Item_date_func(a, b, c), from_tz_cached(0), to_tz_cached(0) {}
   longlong val_int();
   double val_real() { return (double) val_int(); }
   String *val_str(String *str);
@@ -558,6 +561,7 @@ class Item_func_convert_tz :public Item_date_func
   bool fix_fields(THD *, struct st_table_list *, Item **);
   void fix_length_and_dec();
   bool get_date(TIME *res, uint fuzzy_date);
+  void cleanup();
 };
 
 

sql/set_var.cc

@@ -2505,8 +2505,15 @@ bool sys_var_thd_time_zone::check(THD *thd, set_var *var)
 
 bool sys_var_thd_time_zone::update(THD *thd, set_var *var)
 {
-  /* We are using Time_zone object found during check() phase */
-  *get_tz_ptr(thd,var->type)= var->save_result.time_zone;
+  /* We are using Time_zone object found during check() phase. */
+  if (var->type == OPT_GLOBAL)
+  {
+    pthread_mutex_lock(&LOCK_global_system_variables);
+    global_system_variables.time_zone= var->save_result.time_zone;
+    pthread_mutex_unlock(&LOCK_global_system_variables);
+  }
+  else
+    thd->variables.time_zone= var->save_result.time_zone;
   return 0;
 }
 
@@ -2518,27 +2525,25 @@ byte *sys_var_thd_time_zone::value_ptr(THD *thd, enum_var_type type,
     We can use ptr() instead of c_ptr() here because String contaning
     time zone name is guaranteed to be zero ended.
   */
-  return (byte *)((*get_tz_ptr(thd,type))->get_name()->ptr());
-}
-
-
-Time_zone** sys_var_thd_time_zone::get_tz_ptr(THD *thd, 
-                                              enum_var_type type)
-{
   if (type == OPT_GLOBAL)
-    return &global_system_variables.time_zone;
+    return (byte *)(global_system_variables.time_zone->get_name()->ptr());
   else
-    return &thd->variables.time_zone;
+    return (byte *)(thd->variables.time_zone->get_name()->ptr());
 }
 
 
 void sys_var_thd_time_zone::set_default(THD *thd, enum_var_type type)
 {
+ pthread_mutex_lock(&LOCK_global_system_variables);
  if (type == OPT_GLOBAL)
  {
    if (default_tz_name)
    {
      String str(default_tz_name, &my_charset_latin1);
+     /*
+       We are guaranteed to find this time zone since its existence
+       is checked during start-up.
+     */
      global_system_variables.time_zone=
        my_tz_find(&str, thd->lex->time_zone_tables_used);
    }
@@ -2547,6 +2552,7 @@ void sys_var_thd_time_zone::set_default(THD *thd, enum_var_type type)
  }
  else
    thd->variables.time_zone= global_system_variables.time_zone;
+ pthread_mutex_unlock(&LOCK_global_system_variables);
 }
 
 

sql/set_var.h

@@ -724,7 +724,6 @@ class sys_var_thd_time_zone :public sys_var_thd
   bool update(THD *thd, set_var *var);
   byte *value_ptr(THD *thd, enum_var_type type, LEX_STRING *base);
   virtual void set_default(THD *thd, enum_var_type type);
-  Time_zone **get_tz_ptr(THD *thd, enum_var_type type);
 };
 
 

sql/tztime.cc

@@ -1807,8 +1807,11 @@ tz_load_from_open_tables(const String *tz_name, TABLE_LIST *tz_tables)
                               0, HA_READ_KEY_EXACT))
   {
 #ifdef EXTRA_DEBUG    
-    sql_print_error("Can't find description of time zone '%.*s'", tz_name->length(),
-                    tz_name->ptr());
+    /*
+      Most probably user has mistyped time zone name, so no need to bark here
+      unless we need it for debugging.
+    */
+    sql_print_error("Can't find description of time zone '%s'", tz_name_buff);
 #endif
     goto end;
   }