Fix for bug #6116 "SET time_zone := ... requires access to

mysql.time_zone* tables".

We are excluding implicitly used time zone tables from privilege
checking.


mysql-test/r/timezone2.result:
  Added test for bug #6116 "SET time_zone := ... requires access to 
  mysql.time_zone tables"
mysql-test/t/timezone2.test:
  Added test for bug #6116 "SET time_zone := ... requires access to 
  mysql.time_zone tables"
sql/sql_parse.cc:
  check_table_access(): we should avoid privilege checking for implicitly
  used time zone tables.
sql/tztime.cc:
  Indicated dependancy between my_tz_get_table_list() function and
  my_tz_check_n_skip_implicit_tables() function.
sql/tztime.h:
  Added my_tz_check_n_skip_implicit_tables() function which allows easily
  determine whenever we have found beggining of the list of implicitly used
  time zone tables and fast-forward to its end.

mysql-test/r/timezone2.result

@@ -251,3 +251,23 @@ select convert_tz(ts, @@time_zone, 'Japan') from t1;
 convert_tz(ts, @@time_zone, 'Japan')
 2001-09-09 10:46:40
 drop table t1;
+delete from mysql.user where user like 'mysqltest\_%';
+delete from mysql.db where user like 'mysqltest\_%';
+delete from mysql.tables_priv where user like 'mysqltest\_%';
+delete from mysql.columns_priv where user like 'mysqltest\_%';
+flush privileges;
+grant usage on mysqltest.* to mysqltest_1@localhost;
+show grants for current_user();
+Grants for mysqltest_1@localhost
+GRANT USAGE ON *.* TO 'mysqltest_1'@'localhost'
+set time_zone= '+00:00';
+set time_zone= 'Europe/Moscow';
+select convert_tz('2004-10-21 19:00:00', 'Europe/Moscow', 'UTC');
+convert_tz('2004-10-21 19:00:00', 'Europe/Moscow', 'UTC')
+2004-10-21 15:00:00
+select * from mysql.time_zone_name;
+ERROR 42000: Access denied for user 'mysqltest_1'@'localhost' to database 'mysql'
+select Name, convert_tz('2004-10-21 19:00:00', Name, 'UTC') from mysql.time_zone_name;
+ERROR 42000: Access denied for user 'mysqltest_1'@'localhost' to database 'mysql'
+delete from mysql.user where user like 'mysqltest\_%';
+flush privileges;

mysql-test/t/timezone2.test

@@ -199,3 +199,31 @@ insert into t1 (ts) values (now());
 select convert_tz(ts, @@time_zone, 'Japan') from t1;
 drop table t1;
 
+#
+# Test for bug #6116 "SET time_zone := ... requires access to mysql.time_zone
+# tables". We should allow implicit access to time zone description tables
+# even for unprivileged users.
+#
+
+delete from mysql.user where user like 'mysqltest\_%';
+delete from mysql.db where user like 'mysqltest\_%';
+delete from mysql.tables_priv where user like 'mysqltest\_%';
+delete from mysql.columns_priv where user like 'mysqltest\_%';
+flush privileges;
+
+grant usage on mysqltest.* to mysqltest_1@localhost;
+connect (tzuser, localhost, mysqltest_1,,);
+connection tzuser;
+show grants for current_user();
+set time_zone= '+00:00';
+set time_zone= 'Europe/Moscow';
+select convert_tz('2004-10-21 19:00:00', 'Europe/Moscow', 'UTC');
+# But still these two statements should not work:
+--error 1044
+select * from mysql.time_zone_name;
+--error 1044
+select Name, convert_tz('2004-10-21 19:00:00', Name, 'UTC') from mysql.time_zone_name;
+
+connection default;
+delete from mysql.user where user like 'mysqltest\_%';
+flush privileges;

sql/sql_parse.cc

@@ -3724,7 +3724,10 @@ check_table_access(THD *thd, ulong want_access,TABLE_LIST *tables,
   TABLE_LIST *org_tables=tables;
   for (; tables ; tables=tables->next)
   {
-    if (tables->derived || (tables->table && (int)tables->table->tmp_table))
+    if (tables->derived ||
+        (tables->table && (int)tables->table->tmp_table) ||
+        my_tz_check_n_skip_implicit_tables(&tables,
+                                           thd->lex->time_zone_tables_used))
       continue;
     if ((thd->master_access & want_access) == (want_access & ~EXTRA_ACL) &&
 	thd->db)

sql/tztime.cc

@@ -1434,6 +1434,10 @@ tz_init_table_list(TABLE_LIST *tz_tabs)
     This function creates list of TABLE_LIST objects allocated in thd's
     memroot, which can be used for opening of time zone tables.
 
+  NOTE
+    my_tz_check_n_skip_implicit_tables() function depends on fact that
+    elements of list created are allocated as TABLE_LIST[4] array.
+
   RETURN VALUES
     Returns pointer to first TABLE_LIST object, (could be 0 if time zone
     tables don't exist) and &fake_time_zone_tables_list in case of error.

sql/tztime.h

@@ -64,6 +64,35 @@ 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();
 
+
+/*
+  Check if we have pointer to the beggining of list of implictly used
+  time zone tables and fast-forward to its end.
+
+  SYNOPSIS
+    my_tz_check_n_skip_implicit_tables()
+      table     - (in/out) pointer to element of table list to check
+      tz_tables - list of implicitly used time zone tables received
+                  from my_tz_get_table_list() function.
+
+  NOTE
+    This function relies on my_tz_get_table_list() implementation.
+
+  RETURN VALUE
+    TRUE  - if table points to the beggining of tz_tables list
+    FALSE - otherwise.
+*/
+inline bool my_tz_check_n_skip_implicit_tables(TABLE_LIST **table,
+                                               TABLE_LIST *tz_tables)
+{
+  if (*table == tz_tables)
+  {
+    (*table)+= 3;
+    return TRUE;
+  }
+  return FALSE;
+}
+
 /* 
   Maximum length of time zone name that we support 
   (Time zone name is char(64) in db)