Fix for 5.1 for BUG#10491: Server returns data as charset binary

SHOW CREATE TABLE or SELECT FROM I_S.

This is the last patch for this bug, which depends on the big
CS patch and was pending.

The problem was that SHOW CREATE statements returned original
queries in the binary character set. That could cause the query
to be unreadable.

The fix is to use original character_set_client when sending
the original query to the client. In order to preserve the query
in mysqldump, 'binary' character set results should be set when
issuing SHOW CREATE statement. If either source or destination
character set is 'binary' , no conversion is performed.
The idea is that since the source character set is no longer
'binary', we fix the destination character set to still produce
valid dumps.

client/mysqldump.c

@@ -1201,6 +1201,20 @@ static void restore_time_zone(FILE *sql_file,
           (const char *) delimiter);
 }
 
+
+static int switch_character_set_results(MYSQL *mysql, const char *cs_name)
+{
+  char query_buffer[QUERY_LENGTH];
+  size_t query_length;
+
+  query_length= my_snprintf(query_buffer,
+                            sizeof (query_buffer),
+                            "SET SESSION character_set_results = '%s'",
+                            (const char *) cs_name);
+
+  return mysql_real_query(mysql, query_buffer, query_length);
+}
+
 /*
   Open a new .sql file to dump the table or view into
 
@@ -1706,6 +1720,9 @@ static uint dump_events_for_db(char *db)
     if (fetch_db_collation(db_name_buff, db_cl_name, sizeof (db_cl_name)))
       DBUG_RETURN(1);
 
+    if (switch_character_set_results(mysql, "binary"))
+      DBUG_RETURN(1);
+
     while ((event_list_row= mysql_fetch_row(event_list_res)) != NULL)
     {
       event_name= quote_name(event_list_row[1], name_buff, 0);
@@ -1774,6 +1791,9 @@ static uint dump_events_for_db(char *db)
     } /* end of list of events */
     fprintf(sql_file, "DELIMITER ;\n");
     fprintf(sql_file, "/*!50106 SET TIME_ZONE= @save_time_zone */ ;\n");
+
+    if (switch_character_set_results(mysql, default_charset))
+      DBUG_RETURN(1);
   }
   mysql_free_result(event_list_res);
 
@@ -1853,6 +1873,9 @@ static uint dump_routines_for_db(char *db)
   if (fetch_db_collation(db_name_buff, db_cl_name, sizeof (db_cl_name)))
     DBUG_RETURN(1);
 
+  if (switch_character_set_results(mysql, "binary"))
+    DBUG_RETURN(1);
+
   /* 0, retrieve and dump functions, 1, procedures */
   for (i= 0; i <= 1; i++)
   {
@@ -1990,6 +2013,9 @@ static uint dump_routines_for_db(char *db)
     mysql_free_result(routine_list_res);
   } /* end of for i (0 .. 1)  */
 
+  if (switch_character_set_results(mysql, default_charset))
+    DBUG_RETURN(1);
+
   if (lock_tables)
     VOID(mysql_query_with_error_report(mysql, 0, "UNLOCK TABLES"));
   DBUG_RETURN(0);
@@ -2542,6 +2568,9 @@ static void dump_triggers_for_table(char *table, char *db_name)
   if (fetch_db_collation(db_name, db_cl_name, sizeof (db_cl_name)))
     DBUG_VOID_RETURN;
 
+  if (switch_character_set_results(mysql, "binary"))
+    DBUG_VOID_RETURN;
+
   /* Dump triggers. */
 
   while ((row= mysql_fetch_row(result)))
@@ -2637,6 +2666,9 @@ static void dump_triggers_for_table(char *table, char *db_name)
 
   mysql_free_result(result);
 
+  if (switch_character_set_results(mysql, default_charset))
+    DBUG_VOID_RETURN;
+
   /*
     make sure to set back opt_compatible mode to
     original value
@@ -4390,14 +4422,22 @@ static my_bool get_view_structure(char *table, char* db)
   result_table=     quote_name(table, table_buff, 1);
   opt_quoted_table= quote_name(table, table_buff2, 0);
 
+  if (switch_character_set_results(mysql, "binary"))
+    DBUG_RETURN(1);
+
   my_snprintf(query, sizeof(query), "SHOW CREATE TABLE %s", result_table);
+
   if (mysql_query_with_error_report(mysql, &table_res, query))
+  {
+    switch_character_set_results(mysql, default_charset);
     DBUG_RETURN(0);
+  }
 
   /* Check if this is a view */
   field= mysql_fetch_field_direct(table_res, 0);
   if (strcmp(field->name, "View") != 0)
   {
+    switch_character_set_results(mysql, default_charset);
     verbose_msg("-- It's base table, skipped\n");
     DBUG_RETURN(0);
   }
@@ -4540,6 +4580,9 @@ static my_bool get_view_structure(char *table, char* db)
     dynstr_free(&ds_view);
   }
 
+  if (switch_character_set_results(mysql, default_charset))
+    DBUG_RETURN(1);
+
   /* If a separate .sql file was opened, close it now */
   if (sql_file != md_result_file)
   {

mysql-test/r/show_check.result

@@ -1282,4 +1282,43 @@ t1_bi		CREATE DEFINER=`root`@`localhost` TRIGGER t1_bi BEFORE INSERT ON t1 FOR E
 DROP TABLE t1;
 DROP PROCEDURE p1;
 DEALLOCATE PREPARE stmt1;
+set names koi8r;
+DROP VIEW IF EXISTS v1;
+DROP PROCEDURE IF EXISTS p1;
+DROP FUNCTION IF EXISTS f1;
+DROP TABLE IF EXISTS t1;
+DROP EVENT IF EXISTS ev1;
+CREATE VIEW v1 AS SELECT '' AS test;
+CREATE PROCEDURE p1() SELECT '' AS test;
+CREATE FUNCTION f1() RETURNS CHAR(10) RETURN '';
+CREATE TABLE t1(c1 CHAR(10));
+CREATE TRIGGER t1_bi BEFORE INSERT ON t1
+FOR EACH ROW
+SET NEW.c1 = '';
+CREATE EVENT ev1 ON SCHEDULE AT '2030-01-01 00:00:00' DO SELECT '' AS test;
+set names utf8;
+SHOW CREATE VIEW v1;
+View	Create View	character_set_client	collation_connection
+v1	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS select _koi8r'тест' AS `test`	koi8r	koi8r_general_ci
+SHOW CREATE PROCEDURE p1;
+Procedure	sql_mode	Create Procedure	character_set_client	collation_connection	Database Collation
+p1		CREATE DEFINER=`root`@`localhost` PROCEDURE `p1`()
+SELECT 'тест' AS test	koi8r	koi8r_general_ci	latin1_swedish_ci
+SHOW CREATE FUNCTION f1;
+Function	sql_mode	Create Function	character_set_client	collation_connection	Database Collation
+f1		CREATE DEFINER=`root`@`localhost` FUNCTION `f1`() RETURNS char(10) CHARSET latin1
+RETURN 'тест'	koi8r	koi8r_general_ci	latin1_swedish_ci
+SHOW CREATE TRIGGER t1_bi;
+Trigger	sql_mode	SQL Original Statement	character_set_client	collation_connection	Database Collation
+t1_bi		CREATE DEFINER=`root`@`localhost` TRIGGER t1_bi BEFORE INSERT ON t1
+FOR EACH ROW
+SET NEW.c1 = 'тест'	koi8r	koi8r_general_ci	latin1_swedish_ci
+SHOW CREATE EVENT ev1;
+Event	sql_mode	time_zone	Create Event	character_set_client	collation_connection	Database Collation
+ev1		SYSTEM	CREATE EVENT `ev1` ON SCHEDULE AT '2030-01-01 00:00:00' ON COMPLETION NOT PRESERVE ENABLE DO SELECT 'тест' AS test	koi8r	koi8r_general_ci	latin1_swedish_ci
+DROP VIEW v1;
+DROP PROCEDURE p1;
+DROP FUNCTION f1;
+DROP TABLE t1;
+DROP EVENT ev1;
 End of 5.1 tests

mysql-test/t/show_check.test

@@ -897,4 +897,68 @@ DROP TABLE t1;
 DROP PROCEDURE p1;
 DEALLOCATE PREPARE stmt1;
 
+#
+# BUG#10491: Server returns data as charset binary SHOW CREATE TABLE or SELECT
+# FROM INFORMATION_SCHEMA.
+#
+# Before the change performed to fix the bug, the metadata of the output of
+# SHOW CREATE statements would always describe the result as 'binary'. That
+# would ensure that the result is never converted to character_set_client
+# (which was essential to mysqldump). Now we return to the client the actual
+# character set of the object -- which is character_set_client of the
+# connection that issues the CREATE statement, and this triggers an automatic
+# conversion to character_set_results of the connection that issues SHOW CREATE
+# statement.
+#
+# This test demonstrates that this conversion indeed is taking place.
+#
+
+# Prepare: create objects in a one character set.
+
+set names koi8r;
+
+--disable_warnings
+DROP VIEW IF EXISTS v1;
+DROP PROCEDURE IF EXISTS p1;
+DROP FUNCTION IF EXISTS f1;
+DROP TABLE IF EXISTS t1;
+DROP EVENT IF EXISTS ev1;
+--enable_warnings
+
+CREATE VIEW v1 AS SELECT '' AS test;
+
+CREATE PROCEDURE p1() SELECT '' AS test;
+
+CREATE FUNCTION f1() RETURNS CHAR(10) RETURN '';
+
+CREATE TABLE t1(c1 CHAR(10));
+CREATE TRIGGER t1_bi BEFORE INSERT ON t1
+  FOR EACH ROW
+    SET NEW.c1 = '';
+
+CREATE EVENT ev1 ON SCHEDULE AT '2030-01-01 00:00:00' DO SELECT '' AS test;
+
+# Test: switch the character set and show that SHOW CREATE output is
+# automatically converted to the new character_set_client.
+
+set names utf8;
+
+SHOW CREATE VIEW v1;
+
+SHOW CREATE PROCEDURE p1;
+
+SHOW CREATE FUNCTION f1;
+
+SHOW CREATE TRIGGER t1_bi;
+
+SHOW CREATE EVENT ev1;
+
+# Cleanup.
+
+DROP VIEW v1;
+DROP PROCEDURE p1;
+DROP FUNCTION f1;
+DROP TABLE t1;
+DROP EVENT ev1;
+
 --echo End of 5.1 tests

sql/events.cc

@@ -717,7 +717,8 @@ send_show_create_event(THD *thd, Event_timed *et, Protocol *protocol)
   protocol->store(et->name.str, et->name.length, system_charset_info);
   protocol->store(sql_mode.str, sql_mode.length, system_charset_info);
   protocol->store(tz_name->ptr(), tz_name->length(), system_charset_info);
-  protocol->store(show_str.c_ptr(), show_str.length(), &my_charset_bin);
+  protocol->store(show_str.c_ptr(), show_str.length(),
+                  et->creation_ctx->get_client_cs());
   protocol->store(et->creation_ctx->get_client_cs()->csname,
                   strlen(et->creation_ctx->get_client_cs()->csname),
                   system_charset_info);

sql/sp_head.cc

@@ -2260,7 +2260,8 @@ sp_head::show_create_routine(THD *thd, int type)
   protocol->store(sql_mode.str, sql_mode.length, system_charset_info);
 
   if (full_access)
-    protocol->store(m_defstr.str, m_defstr.length, &my_charset_bin);
+    protocol->store(m_defstr.str, m_defstr.length,
+                    m_creation_ctx->get_client_cs());
   else
     protocol->store_null();
 

sql/sql_show.cc

@@ -639,7 +639,8 @@ mysqld_show_create(THD *thd, TABLE_LIST *table_list)
 
   if (table_list->view)
   {
-    protocol->store(buffer.ptr(), buffer.length(), &my_charset_bin);
+    protocol->store(buffer.ptr(), buffer.length(),
+                    table_list->view_creation_ctx->get_client_cs());
 
     protocol->store(table_list->view_creation_ctx->get_client_cs()->csname,
                     system_charset_info);
@@ -5983,6 +5984,8 @@ static bool show_create_trigger_impl(THD *thd,
   LEX_STRING trg_connection_cl_name;
   LEX_STRING trg_db_cl_name;
 
+  CHARSET_INFO *trg_client_cs;
+
   /*
     TODO: Check privileges here. This functionality will be added by
     implementation of the following WL items:
@@ -6008,6 +6011,11 @@ static bool show_create_trigger_impl(THD *thd,
                                                      trg_sql_mode,
                                                      &trg_sql_mode_str);
 
+  /* Resolve trigger client character set. */
+
+  if (resolve_charset(trg_client_cs_name.str, NULL, &trg_client_cs))
+    return TRUE;
+
   /* Send header. */
 
   fields.push_back(new Item_empty_string("Trigger", NAME_LEN));
@@ -6054,7 +6062,7 @@ static bool show_create_trigger_impl(THD *thd,
 
   p->store(trg_sql_original_stmt.str,
            trg_sql_original_stmt.length,
-           &my_charset_bin);
+           trg_client_cs);
 
   p->store(trg_client_cs_name.str,
            trg_client_cs_name.length,