MDEV-16157 federated corrupts timestamps

do "set time_zone='+00:00'" on remote server
after connecting.

temporarily reset local time zone to my_tz_OFFSET0
whenever Field::val_str() or Field::store()
methods are used.

mysql-test/suite/federated/timestamps.result

+connect  master,127.0.0.1,root,,test,$MASTER_MYPORT,;
+connect  slave,127.0.0.1,root,,test,$SLAVE_MYPORT,;
+connection master;
+CREATE DATABASE federated;
+connection slave;
+CREATE DATABASE federated;
+connection slave;
+set global time_zone='Europe/Moscow';
+set time_zone='Europe/Moscow';
+create table federated.t1 (dt datetime, ts timestamp, unique(ts));
+connection master;
+set time_zone='+01:00';
+create table t1 engine=federated connection='mysql://root@127.0.0.1:SLAVE_PORT/federated/t1';
+set @@timestamp=1;
+insert t1 values (now(), now());
+set @@timestamp=2147483647;
+insert t1 values (now(), now());
+set @@timestamp=1067121000;
+insert t1 values (now(), now());
+set @@timestamp=1067124600;
+insert t1 values (now(), now());
+set @@timestamp=0;
+select * from t1;
+dt	ts
+1970-01-01 01:00:01	1970-01-01 01:00:01
+2038-01-19 04:14:07	2038-01-19 04:14:07
+2003-10-25 23:30:00	2003-10-25 23:30:00
+2003-10-26 00:30:00	2003-10-26 00:30:00
+delete from t1 where ts='1970-01-01 01:00:01';
+select * from t1;
+dt	ts
+2038-01-19 04:14:07	2038-01-19 04:14:07
+2003-10-25 23:30:00	2003-10-25 23:30:00
+2003-10-26 00:30:00	2003-10-26 00:30:00
+insert t1 values ('1970-01-01 01:00:01', now());
+update t1 set ts=dt;
+select * from t1;
+dt	ts
+1970-01-01 01:00:01	1970-01-01 01:00:01
+2038-01-19 04:14:07	2038-01-19 04:14:07
+2003-10-25 23:30:00	2003-10-25 23:30:00
+2003-10-26 00:30:00	2003-10-26 00:30:00
+select * from t1 where ts='2003-10-25 23:30:00';
+dt	ts
+2003-10-25 23:30:00	2003-10-25 23:30:00
+select * from t1 where ts='2003-10-26 00:30:00';
+dt	ts
+2003-10-26 00:30:00	2003-10-26 00:30:00
+connection slave;
+select * from federated.t1;
+dt	ts
+1970-01-01 01:00:01	1970-01-01 03:00:01
+2038-01-19 04:14:07	2038-01-19 06:14:07
+2003-10-25 23:30:00	2003-10-26 02:30:00
+2003-10-26 00:30:00	2003-10-26 02:30:00
+set global time_zone=default;
+connection master;
+drop table t1;
+connection master;
+DROP TABLE IF EXISTS federated.t1;
+DROP DATABASE IF EXISTS federated;
+connection slave;
+DROP TABLE IF EXISTS federated.t1;
+DROP DATABASE IF EXISTS federated;

mysql-test/suite/federated/timestamps.test

+source have_federatedx.inc;
+source include/federated.inc;
+
+connection slave;
+set global time_zone='Europe/Moscow';
+set time_zone='Europe/Moscow';
+create table federated.t1 (dt datetime, ts timestamp, unique(ts));
+
+connection master;
+set time_zone='+01:00';
+replace_result $SLAVE_MYPORT SLAVE_PORT;
+eval create table t1 engine=federated connection='mysql://root@127.0.0.1:$SLAVE_MYPORT/federated/t1';
+
+set @@timestamp=1; # min value
+insert t1 values (now(), now());
+set @@timestamp=2147483647; # max value
+insert t1 values (now(), now());
+set @@timestamp=1067121000; # DST ambiguous (in Europe/Moscow)
+insert t1 values (now(), now());
+set @@timestamp=1067124600; # DST ambiguous (in Europe/Moscow)
+insert t1 values (now(), now());
+set @@timestamp=0;
+
+# reads
+select * from t1;
+
+# deletes
+delete from t1 where ts='1970-01-01 01:00:01';
+select * from t1;
+
+# updates
+insert t1 values ('1970-01-01 01:00:01', now());
+update t1 set ts=dt;
+select * from t1;
+
+# index lookups
+select * from t1 where ts='2003-10-25 23:30:00';
+select * from t1 where ts='2003-10-26 00:30:00';
+
+connection slave;
+select * from federated.t1;
+set global time_zone=default;
+connection master;
+drop table t1;
+source include/federated_cleanup.inc;

storage/federatedx/federatedx_io_mysql.cc

@@ -453,7 +453,8 @@ int federatedx_io_mysql::actual_query(const char *buffer, size_t length)
     mysql.reconnect= 1;
   }
 
-  error= mysql_real_query(&mysql, buffer, (ulong)length);
+  if (!(error= mysql_real_query(&mysql, STRING_WITH_LEN("set time_zone='+00:00'"))))
+    error= mysql_real_query(&mysql, buffer, (ulong)length);
   
   DBUG_RETURN(error);
 }

storage/federatedx/ha_federatedx.cc

@@ -318,6 +318,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "sql_servers.h"
 #include "sql_analyse.h"                        // append_escaped()
 #include "sql_show.h"                           // append_identifier()
+#include "tztime.h"                             // my_tz_find()
 
 #ifdef I_AM_PARANOID
 #define MIN_PORT 1023
@@ -340,6 +341,8 @@ static const uint sizeof_trailing_comma= sizeof(", ") - 1;
 static const uint sizeof_trailing_and= sizeof(" AND ") - 1;
 static const uint sizeof_trailing_where= sizeof(" WHERE ") - 1;
 
+static Time_zone *UTC= 0;
+
 /* Static declaration for handerton */
 static handler *federatedx_create_handler(handlerton *hton,
                                          TABLE_SHARE *table,
@@ -860,8 +863,10 @@ uint ha_federatedx::convert_row_to_internal_format(uchar *record,
   Field **field;
   int column= 0;
   my_bitmap_map *old_map= dbug_tmp_use_all_columns(table, table->write_set);
+  Time_zone *saved_time_zone= table->in_use->variables.time_zone;
   DBUG_ENTER("ha_federatedx::convert_row_to_internal_format");
 
+  table->in_use->variables.time_zone= UTC;
   lengths= io->fetch_lengths(result);
 
   for (field= table->field; *field; field++, column++)
@@ -885,6 +890,7 @@ uint ha_federatedx::convert_row_to_internal_format(uchar *record,
     }
     (*field)->move_field_offset(-old_ptr);
   }
+  table->in_use->variables.time_zone= saved_time_zone;
   dbug_tmp_restore_column_map(table->write_set, old_map);
   DBUG_RETURN(0);
 }
@@ -1213,6 +1219,7 @@ bool ha_federatedx::create_where_from_key(String *to,
   char tmpbuff[FEDERATEDX_QUERY_BUFFER_SIZE];
   String tmp(tmpbuff, sizeof(tmpbuff), system_charset_info);
   const key_range *ranges[2]= { start_key, end_key };
+  Time_zone *saved_time_zone= table->in_use->variables.time_zone;
   my_bitmap_map *old_map;
   DBUG_ENTER("ha_federatedx::create_where_from_key");
 
@@ -1220,6 +1227,7 @@ bool ha_federatedx::create_where_from_key(String *to,
   if (start_key == NULL && end_key == NULL)
     DBUG_RETURN(1);
 
+  table->in_use->variables.time_zone= UTC;
   old_map= dbug_tmp_use_all_columns(table, table->write_set);
   for (uint i= 0; i <= 1; i++)
   {
@@ -1397,6 +1405,7 @@ bool ha_federatedx::create_where_from_key(String *to,
     }
   }
   dbug_tmp_restore_column_map(table->write_set, old_map);
+  table->in_use->variables.time_zone= saved_time_zone;
 
   if (both_not_null)
     if (tmp.append(STRING_WITH_LEN(") ")))
@@ -1412,6 +1421,7 @@ bool ha_federatedx::create_where_from_key(String *to,
 
 err:
   dbug_tmp_restore_column_map(table->write_set, old_map);
+  table->in_use->variables.time_zone= saved_time_zone;
   DBUG_RETURN(1);
 }
 
@@ -1582,6 +1592,12 @@ static FEDERATEDX_SHARE *get_share(const char *table_name, TABLE *table)
 
   mysql_mutex_lock(&federatedx_mutex);
 
+  if (unlikely(!UTC))
+  {
+    String tz_00_name(STRING_WITH_LEN("+00:00"), &my_charset_bin);
+    UTC= my_tz_find(current_thd, &tz_00_name);
+  }
+
   tmp_share.share_key= table_name;
   tmp_share.share_key_length= (int)strlen(table_name);
   if (parse_url(&mem_root, &tmp_share, table->s, 0))
@@ -1978,9 +1994,11 @@ int ha_federatedx::write_row(uchar *buf)
   String insert_field_value_string(insert_field_value_buffer,
                                    sizeof(insert_field_value_buffer),
                                    &my_charset_bin);
+  Time_zone *saved_time_zone= table->in_use->variables.time_zone;
   my_bitmap_map *old_map= dbug_tmp_use_all_columns(table, table->read_set);
   DBUG_ENTER("ha_federatedx::write_row");
 
+  table->in_use->variables.time_zone= UTC;
   values_string.length(0);
   insert_field_value_string.length(0);
 
@@ -2033,6 +2051,7 @@ int ha_federatedx::write_row(uchar *buf)
     }
   }
   dbug_tmp_restore_column_map(table->read_set, old_map);
+  table->in_use->variables.time_zone= saved_time_zone;
 
   /*
     if there were no fields, we don't want to add a closing paren
@@ -2340,6 +2359,8 @@ int ha_federatedx::update_row(const uchar *old_data, const uchar *new_data)
     field=oldvalue
   */
 
+  Time_zone *saved_time_zone= table->in_use->variables.time_zone;
+  table->in_use->variables.time_zone= UTC;
   for (Field **field= table->field; *field; field++)
   {
     if (bitmap_is_set(table->write_set, (*field)->field_index))
@@ -2391,6 +2412,7 @@ int ha_federatedx::update_row(const uchar *old_data, const uchar *new_data)
       where_string.append(STRING_WITH_LEN(" AND "));
     }
   }
+  table->in_use->variables.time_zone= saved_time_zone;
 
   /* Remove last ', '. This works as there must be at least on updated field */
   update_string.length(update_string.length() - sizeof_trailing_comma);
@@ -2451,6 +2473,8 @@ int ha_federatedx::delete_row(const uchar *buf)
                share->table_name_length, ident_quote_char);
   delete_string.append(STRING_WITH_LEN(" WHERE "));
 
+  Time_zone *saved_time_zone= table->in_use->variables.time_zone;
+  table->in_use->variables.time_zone= UTC;
   for (Field **field= table->field; *field; field++)
   {
     Field *cur_field= *field;
@@ -2478,6 +2502,7 @@ int ha_federatedx::delete_row(const uchar *buf)
       delete_string.append(STRING_WITH_LEN(" AND "));
     }
   }
+  table->in_use->variables.time_zone= saved_time_zone;
 
   // Remove trailing AND
   delete_string.length(delete_string.length() - sizeof_trailing_and);