Fix for bug #4508 "CONVERT_TZ() function with new time zone as param crashes server".

Instead of trying to open time zone tables during calculation of CONVERT_TZ() function
or setting of @@time_zone variable we should open and lock them with the rest of 
statement's table (so we should add them to global table list) and after that use such 
pre-opened tables for loading info about time zones.

mysql-test/r/timezone2.result

@@ -244,3 +244,10 @@ NULL
 select convert_tz( NULL, 'MET', 'UTC');
 convert_tz( NULL, 'MET', 'UTC')
 NULL
+create table t1 (ts timestamp);
+set timestamp=1000000000;
+insert into t1 (ts) values (now());
+select convert_tz(ts, @@time_zone, 'Japan') from t1;
+convert_tz(ts, @@time_zone, 'Japan')
+2001-09-09 10:46:40
+drop table t1;

mysql-test/t/timezone2.test

@@ -187,3 +187,15 @@ select convert_tz('2003-12-31 04:00:00', 'SomeNotExistingTimeZone', 'UTC');
 select convert_tz('2003-12-31 04:00:00', 'MET', 'SomeNotExistingTimeZone');
 select convert_tz('2003-12-31 04:00:00', 'MET', NULL);
 select convert_tz( NULL, 'MET', 'UTC');
+
+#
+# Test for bug #4508 "CONVERT_TZ() function with new time zone as param
+# crashes server." (Was caused by improperly worked mechanism of time zone
+# dynamical loading).
+#
+create table t1 (ts timestamp);
+set timestamp=1000000000;
+insert into t1 (ts) values (now());
+select convert_tz(ts, @@time_zone, 'Japan') from t1;
+drop table t1;
+

scripts/mysql_create_system_tables.sh

@@ -307,7 +307,8 @@ then
   then
     i_tzn="$i_tzn INSERT INTO time_zone_name (Name, Time_Zone_id) VALUES"
     i_tzn="$i_tzn   ('MET', 1), ('UTC', 2), ('Universal', 2), "
-    i_tzn="$i_tzn   ('Europe/Moscow',3), ('leap/Europe/Moscow',4);"
+    i_tzn="$i_tzn   ('Europe/Moscow',3), ('leap/Europe/Moscow',4), "
+    i_tzn="$i_tzn   ('Japan', 5);"
   fi
 fi
 
@@ -327,7 +328,7 @@ then
   if test "$1" = "test" 
   then
     i_tz="$i_tz INSERT INTO time_zone (Time_zone_id, Use_leap_seconds)" 
-    i_tz="$i_tz   VALUES (1,'N'), (2,'N'), (3,'N'), (4,'Y');"
+    i_tz="$i_tz   VALUES (1,'N'), (2,'N'), (3,'N'), (4,'Y'), (5,'N');"
   fi
 fi
 
@@ -546,7 +547,8 @@ then
     i_tzt="$i_tzt  ,(4, 2045689222, 8) ,(4, 2058390022, 9)"
     i_tzt="$i_tzt  ,(4, 2077138822, 8) ,(4, 2090444422, 9)"
     i_tzt="$i_tzt  ,(4, 2108588422, 8) ,(4, 2121894022, 9)"
-    i_tzt="$i_tzt  ,(4, 2140038022, 8);"
+    i_tzt="$i_tzt  ,(4, 2140038022, 8)"
+    i_tzt="$i_tzt  ,(5, -1009875600, 1);"
   fi
 fi
 
@@ -584,7 +586,8 @@ then
     i_tztt="$i_tztt  ,(4, 4, 10800, 0, 'MSK') ,(4, 5, 14400, 1, 'MSD')"
     i_tztt="$i_tztt  ,(4, 6, 18000, 1, 'MSD') ,(4, 7, 7200, 0, 'EET')"
     i_tztt="$i_tztt  ,(4, 8, 10800, 0, 'MSK') ,(4, 9, 14400, 1, 'MSD')"
-    i_tztt="$i_tztt  ,(4, 10, 10800, 1, 'EEST') ,(4, 11, 7200, 0, 'EET');"
+    i_tztt="$i_tztt  ,(4, 10, 10800, 1, 'EEST') ,(4, 11, 7200, 0, 'EET')"
+    i_tztt="$i_tztt  ,(5, 0, 32400, 0, 'CJT') ,(5, 1, 32400, 0, 'JST');"
   fi
 fi
 

sql/item_create.cc

@@ -89,11 +89,6 @@ Item *create_func_conv(Item* a, Item *b, Item *c)
   return new Item_func_conv(a,b,c);
 }
 
-Item *create_func_convert_tz(Item* a, Item *b, Item *c)
-{
-  return new Item_func_convert_tz(a,b,c);
-}
-
 Item *create_func_cos(Item* a)
 {
   return new Item_func_cos(a);

sql/item_create.h

@@ -31,7 +31,6 @@ Item *create_func_char_length(Item* a);
 Item *create_func_cast(Item *a, Cast_target cast_type, int len, CHARSET_INFO *cs);
 Item *create_func_connection_id(void);
 Item *create_func_conv(Item* a, Item *b, Item *c);
-Item *create_func_convert_tz(Item* a, Item *b, Item *c);
 Item *create_func_cos(Item* a);
 Item *create_func_cot(Item* a);
 Item *create_func_crc32(Item* a);

sql/item_timefunc.cc

@@ -1648,19 +1648,29 @@ bool Item_func_from_unixtime::get_date(TIME *ltime,
 
 
 void Item_func_convert_tz::fix_length_and_dec()
-{ 
-  String str;
-  
-  thd= current_thd;
+{
   collation.set(&my_charset_bin);
   decimals= 0;
   max_length= MAX_DATETIME_WIDTH*MY_CHARSET_BIN_MB_MAXLEN;
+}
+
+
+bool
+Item_func_convert_tz::fix_fields(THD *thd_arg, TABLE_LIST *tables_arg, Item **ref)
+{
+  String str;
+  if (Item_date_func::fix_fields(thd_arg, tables_arg, ref))
+    return 1;
+
+  tz_tables= thd_arg->lex->time_zone_tables_used;
 
   if (args[1]->const_item())
-    from_tz= my_tz_find(thd, args[1]->val_str(&str));
-  
+    from_tz= my_tz_find(args[1]->val_str(&str), tz_tables);
+
   if (args[2]->const_item())
-    to_tz= my_tz_find(thd, args[2]->val_str(&str));
+    to_tz= my_tz_find(args[2]->val_str(&str), tz_tables);
+
+  return 0;
 }
 
 
@@ -1701,10 +1711,10 @@ bool Item_func_convert_tz::get_date(TIME *ltime,
   String str;
   
   if (!args[1]->const_item())
-    from_tz= my_tz_find(thd, args[1]->val_str(&str));
+    from_tz= my_tz_find(args[1]->val_str(&str), tz_tables);
   
   if (!args[2]->const_item())
-    to_tz= my_tz_find(thd, args[2]->val_str(&str));
+    to_tz= my_tz_find(args[2]->val_str(&str), tz_tables);
   
   if (from_tz==0 || to_tz==0 || get_arg0_date(ltime, 0))
   {

sql/item_timefunc.h

@@ -531,9 +531,22 @@ class Item_func_from_unixtime :public Item_date_func
 */
 class Time_zone;
 
+/*
+  This class represents CONVERT_TZ() function.
+  The important fact about this function that it is handled in special way.
+  When such function is met in expression time_zone system tables are added
+  to global list of tables to open, so later those already opened and locked
+  tables can be used during this function calculation for loading time zone
+  descriptions.
+*/
 class Item_func_convert_tz :public Item_date_func
 {
-  THD *thd;
+  /* Cached pointer to list of pre-opened time zone tables. */
+  TABLE_LIST *tz_tables;
+  /*
+    If time zone parameters are constants we are caching objects that
+    represent them.
+  */
   Time_zone *from_tz, *to_tz;
  public:
   Item_func_convert_tz(Item *a, Item *b, Item *c):
@@ -542,6 +555,7 @@ class Item_func_convert_tz :public Item_date_func
   double val() { return (double) val_int(); }
   String *val_str(String *str);
   const char *func_name() const { return "convert_tz"; }
+  bool fix_fields(THD *, struct st_table_list *, Item **);
   void fix_length_and_dec();
   bool get_date(TIME *res, uint fuzzy_date);
 };

sql/lex.h

@@ -499,7 +499,7 @@ static SYMBOL sql_functions[] = {
   { "CONNECTION_ID",	F_SYM(FUNC_ARG0),0,CREATE_FUNC(create_func_connection_id)},
   { "CONTAINS",		F_SYM(FUNC_ARG2),0,CREATE_FUNC_GEOM(create_func_contains)},
   { "CONV",		F_SYM(FUNC_ARG3),0,CREATE_FUNC(create_func_conv)},
-  { "CONVERT_TZ",	F_SYM(FUNC_ARG3),0,CREATE_FUNC(create_func_convert_tz)},
+  { "CONVERT_TZ",	SYM(CONVERT_TZ_SYM)},
   { "COUNT",		SYM(COUNT_SYM)},
   { "COS",		F_SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_cos)},
   { "COT",		F_SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_cot)},

sql/mysql_priv.h

@@ -500,7 +500,6 @@ int mysql_select(THD *thd, Item ***rref_pointer_array,
 		 select_result *result, SELECT_LEX_UNIT *unit, 
 		 SELECT_LEX *select_lex);
 void free_underlaid_joins(THD *thd, SELECT_LEX *select);
-void fix_tables_pointers(SELECT_LEX *select_lex);
 int mysql_explain_union(THD *thd, SELECT_LEX_UNIT *unit,
 			select_result *result);
 int mysql_explain_select(THD *thd, SELECT_LEX *sl, char const *type,

sql/set_var.cc

@@ -2372,8 +2372,9 @@ bool sys_var_thd_time_zone::check(THD *thd, set_var *var)
     return 1;
   }
 #endif
-  
-  if (!(var->save_result.time_zone= my_tz_find(thd, res)))
+
+  if (!(var->save_result.time_zone=
+          my_tz_find(res, thd->lex->time_zone_tables_used)))
   {
     my_error(ER_UNKNOWN_TIME_ZONE, MYF(0), res ? res->c_ptr() : "NULL");
     return 1;
@@ -2418,7 +2419,8 @@ void sys_var_thd_time_zone::set_default(THD *thd, enum_var_type type)
    if (default_tz_name)
    {
      String str(default_tz_name, &my_charset_latin1);
-     global_system_variables.time_zone= my_tz_find(thd, &str);
+     global_system_variables.time_zone=
+       my_tz_find(&str, thd->lex->time_zone_tables_used);
    }
    else
      global_system_variables.time_zone= my_tz_SYSTEM;

sql/set_var.h

@@ -908,6 +908,7 @@ ulong fix_sql_mode(ulong sql_mode);
 extern sys_var_str sys_charset_system;
 extern sys_var_str sys_init_connect;
 extern sys_var_str sys_init_slave;
+extern sys_var_thd_time_zone sys_time_zone;
 CHARSET_INFO *get_old_charset_by_name(const char *old_name);
 gptr find_named(I_List<NAMED_LIST> *list, const char *name, uint length,
 		NAMED_LIST **found);

sql/sql_base.cc

@@ -1670,7 +1670,22 @@ int open_and_lock_tables(THD *thd, TABLE_LIST *tables)
   uint counter;
   if (open_tables(thd, tables, &counter) || lock_tables(thd, tables, counter))
     DBUG_RETURN(-1);				/* purecov: inspected */
-  fix_tables_pointers(thd->lex->all_selects_list);
+  /*
+    Let us propagate pointers to open tables from global table list
+    to table lists in particular selects if needed.
+  */
+  if (thd->lex->all_selects_list->next_select_in_list() ||
+      thd->lex->time_zone_tables_used)
+  {
+    for (SELECT_LEX *sl= thd->lex->all_selects_list;
+	 sl;
+	 sl= sl->next_select_in_list())
+      for (TABLE_LIST *cursor= (TABLE_LIST *) sl->table_list.first;
+           cursor;
+           cursor=cursor->next)
+        if (cursor->table_list)
+          cursor->table= cursor->table_list->table;
+  }
   DBUG_RETURN(mysql_handle_derived(thd->lex));
 }
 

sql/sql_lex.cc

@@ -22,6 +22,16 @@
 #include <m_ctype.h>
 #include <hash.h>
 
+
+/*
+  Fake table list object, pointer to which is used as special value for
+  st_lex::time_zone_tables_used indicating that we implicitly use time
+  zone tables in this statement but real table list was not yet created.
+  Pointer to it is also returned by my_tz_get_tables_list() as indication
+  of transient error;
+*/
+TABLE_LIST fake_time_zone_tables_list;
+
 /* Macros to look like lex */
 
 #define yyGet()		*(lex->ptr++)
@@ -1292,7 +1302,32 @@ bool st_select_lex_unit::create_total_list(THD *thd_arg, st_lex *lex,
 					   TABLE_LIST **result_arg)
 {
   *result_arg= 0;
-  res= create_total_list_n_last_return(thd_arg, lex, &result_arg);
+  if (!(res= create_total_list_n_last_return(thd_arg, lex, &result_arg)))
+  {
+    /*
+      If time zone tables were used implicitly in statement we should add
+      them to global table list.
+    */
+    if (lex->time_zone_tables_used)
+    {
+      /*
+        Altough we are modifying lex data, it won't raise any problem in
+        case when this lex belongs to some prepared statement or stored
+        procedure: such modification does not change any invariants imposed
+        by requirement to reuse the same lex for multiple executions.
+      */
+      if ((lex->time_zone_tables_used= my_tz_get_table_list(thd)) !=
+          &fake_time_zone_tables_list)
+      {
+        *result_arg= lex->time_zone_tables_used;
+      }
+      else
+      {
+        send_error(thd, 0);
+        res= 1;
+      }
+    }
+  }
   return res;
 }
 

sql/sql_lex.h

@@ -633,6 +633,12 @@ typedef struct st_lex
   bool prepared_stmt_code_is_varref;
   /* Names of user variables holding parameters (in EXECUTE) */
   List<LEX_STRING> prepared_stmt_params; 
+  /*
+    If points to fake_time_zone_tables_list indicates that time zone
+    tables are implicitly used by statement, also is used for holding
+    list of those tables after they are opened.
+  */
+  TABLE_LIST *time_zone_tables_used;
   st_lex() {}
   inline void uncacheable(uint8 cause)
   {
@@ -661,6 +667,7 @@ typedef struct st_lex
 				    TABLE_LIST *local_first);
 } LEX;
 
+extern TABLE_LIST fake_time_zone_tables_list;
 
 void lex_init(void);
 void lex_free(void);

sql/sql_parse.cc

@@ -1897,7 +1897,8 @@ mysql_execute_command(THD *thd)
 #endif
   }
 #endif /* !HAVE_REPLICATION */
-  if (&lex->select_lex != lex->all_selects_list &&
+  if ((&lex->select_lex != lex->all_selects_list ||
+       lex->time_zone_tables_used) &&
       lex->unit.create_total_list(thd, lex, &tables))
     DBUG_VOID_RETURN;
 
@@ -3875,6 +3876,7 @@ mysql_init_query(THD *thd, uchar *buf, uint length)
   lex->lock_option= TL_READ;
   lex->found_colon= 0;
   lex->safe_to_cache_query= 1;
+  lex->time_zone_tables_used= 0;
   lex_start(thd, buf, length);
   thd->select_number= lex->select_lex.select_number= 1;
   thd->free_list= 0;

sql/sql_prepare.cc

@@ -1407,7 +1407,8 @@ static int send_prepare_results(Prepared_statement *stmt, bool text_protocol)
   DBUG_PRINT("enter",("command: %d, param_count: %ld",
                       sql_command, stmt->param_count));
 
-  if (select_lex != lex->all_selects_list &&
+  if ((&lex->select_lex != lex->all_selects_list ||
+       lex->time_zone_tables_used) &&
       lex->unit.create_total_list(thd, lex, &tables))
     DBUG_RETURN(1);
 

sql/sql_select.cc

@@ -213,39 +213,6 @@ int handle_select(THD *thd, LEX *lex, select_result *result)
 }
 
 
-void relink_tables(SELECT_LEX *select_lex)
-{
-  for (TABLE_LIST *cursor= (TABLE_LIST *) select_lex->table_list.first;
-       cursor;
-       cursor=cursor->next)
-    if (cursor->table_list)
-      cursor->table= cursor->table_list->table;
-}
-
-
-void fix_tables_pointers(SELECT_LEX *select_lex)
-{
-  if (select_lex->next_select_in_list())
-  {
-    /* Fix tables 'to-be-unioned-from' list to point at opened tables */
-    for (SELECT_LEX *sl= select_lex;
-	 sl;
-	 sl= sl->next_select_in_list())
-      relink_tables(sl);
-  }
-}
-
-void fix_tables_pointers(SELECT_LEX_UNIT *unit)
-{
-  for (SELECT_LEX *sl= unit->first_select(); sl; sl= sl->next_select())
-  {
-    relink_tables(sl);
-    for (SELECT_LEX_UNIT *un= sl->first_inner_unit(); un; un= un->next_unit())
-      fix_tables_pointers(un);
-  }
-}
-
-
 /*
   Function to setup clauses without sum functions
 */

sql/sql_yacc.yy

@@ -463,6 +463,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
 %token	CASE_SYM
 %token	CONCAT
 %token	CONCAT_WS
+%token  CONVERT_TZ_SYM
 %token	CURDATE
 %token	CURTIME
 %token	DATABASE
@@ -2825,6 +2826,11 @@ simple_expr:
 	  { $$= new Item_func_concat(* $3); }
 	| CONCAT_WS '(' expr ',' expr_list ')'
 	  { $$= new Item_func_concat_ws($3, *$5); }
+	| CONVERT_TZ_SYM '(' expr ',' expr ',' expr ')'
+	  {
+	    Lex->time_zone_tables_used= &fake_time_zone_tables_list;
+	    $$= new Item_func_convert_tz($3, $5, $7);
+	  }
 	| CURDATE optional_braces
 	  { $$= new Item_func_curdate_local(); Lex->safe_to_cache_query=0; }
 	| CURTIME optional_braces
@@ -5308,6 +5314,12 @@ internal_variable_name:
 	  $$.var= tmp;
 	  $$.base_name.str=0;
 	  $$.base_name.length=0;
+          /*
+            If this is time_zone variable we should open time zone
+            describing tables 
+          */
+          if (tmp == &sys_time_zone)
+	    Lex->time_zone_tables_used= &fake_time_zone_tables_list;
 	}
 	| ident '.' ident
 	  {

sql/tztime.h

@@ -59,7 +59,8 @@ public:
 
 extern Time_zone * my_tz_UTC;
 extern Time_zone * my_tz_SYSTEM;
-extern Time_zone * my_tz_find(THD *thd, const String *name);
+extern TABLE_LIST * my_tz_get_table_list(THD *thd);
+extern Time_zone * my_tz_find(const String *name, TABLE_LIST *tz_tables);
 extern my_bool     my_tz_init(THD *org_thd, const char *default_tzname, my_bool bootstrap);
 extern void        my_tz_free();