Bug#57306 SHOW PROCESSLIST does not display string literals well.

Problem: Extended characters outside of ASCII range where not displayed
properly in SHOW PROCESSLIST, because thd_info->query was always sent as 
system_character_set (utf8). This was wrong, because query buffer
is never converted to utf8 - it is always have client character set.

Fix: sending query buffer using query character set

  @ sql/sql_class.cc
  @ sql/sql_class.h
    Introducing a new class CSET_STRING, a LEX_STRING with character set.
    Adding set_query(&CSET_STRING)
    Adding reset_query(), to use instead of set_query(0, NULL).

  @ sql/event_data_objects.cc
    Using reset_query()

  @ sql/log_event.cc
    Using reset_query()
    Adding charset argument to set_query_and_id().

  @ sql/slave.cc
    Using reset_query().

  @ sql/sp_head.cc
    Changing backing up and restore code to use CSET_STRING.

  @ sql/sql_audit.h
    Using CSET_STRING.
    In the "else" branch it's OK not to use
    global_system_variables.character_set_client.
    &my_charset_latin1, which is set in constructor, is fine
    (verified with Sergey Vojtovich).

  @ sql/sql_insert.cc
    Using set_query() with proper character set: table_name is utf8.

  @ sql/sql_parse.cc
    Adding character set argument to set_query_and_id().
    (This is the main point where thd->charset() is stored
     into thd->query_string.cs, for use in "SHOW PROCESSLIST".)
    Using reset_query().
    
  @ sql/sql_prepare.cc
    Storing client character set into thd->query_string.cs.

  @ sql/sql_show.cc
    Using CSET_STRING to fetch and send charset-aware query information
    from threads.

  @ storage/myisam/ha_myisam.cc
    Using set_query() with proper character set: table_name is utf8.

  @ mysql-test/r/show_check.result
  @ mysql-test/t/show_check.test
    Adding tests

1 files changed, 6 insertions, 16 deletions

diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index fc4ab1bd27b..bace0295a04 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -2586,8 +2586,6 @@ Statement::Statement(LEX *lex_arg, MEM_ROOT *mem_root_arg,
   db(NULL),
   db_length(0)
 {
-  query_string.length= 0;
-  query_string.str= NULL;
   name.str= NULL;
 }
 
@@ -2626,15 +2624,6 @@ void Statement::restore_backup_statement(Statement *stmt, Statement *backup)
 }
 
 
-/** Assign a new value to thd->query.  */
-
-void Statement::set_query_inner(char *query_arg, uint32 query_length_arg)
-{
-  query_string.str= query_arg;
-  query_string.length= query_length_arg;
-}
-
-
 void THD::end_statement()
 {
   /* Cleanup SQL processing state to reuse this statement in next query. */
@@ -3167,7 +3156,7 @@ extern "C" struct charset_info_st *thd_charset(MYSQL_THD thd)
 */
 extern "C" char **thd_query(MYSQL_THD thd)
 {
-  return(&thd->query_string.str);
+  return (&thd->query_string.string.str);
 }
 
 /**
@@ -3178,7 +3167,7 @@ extern "C" char **thd_query(MYSQL_THD thd)
 */
 extern "C" LEX_STRING * thd_query_string (MYSQL_THD thd)
 {
-  return(&thd->query_string);
+  return(&thd->query_string.string);
 }
 
 extern "C" int thd_slave_thread(const MYSQL_THD thd)
@@ -3423,20 +3412,21 @@ void THD::set_statement(Statement *stmt)
 
 /** Assign a new value to thd->query.  */
 
-void THD::set_query(char *query_arg, uint32 query_length_arg)
+void THD::set_query(const CSET_STRING &string_arg)
 {
   mysql_mutex_lock(&LOCK_thd_data);
-  set_query_inner(query_arg, query_length_arg);
+  set_query_inner(string_arg);
   mysql_mutex_unlock(&LOCK_thd_data);
 }
 
 /** Assign a new value to thd->query and thd->query_id.  */
 
 void THD::set_query_and_id(char *query_arg, uint32 query_length_arg,
+                           CHARSET_INFO *cs,
                            query_id_t new_query_id)
 {
   mysql_mutex_lock(&LOCK_thd_data);
-  set_query_inner(query_arg, query_length_arg);
+  set_query_inner(query_arg, query_length_arg, cs);
   query_id= new_query_id;
   mysql_mutex_unlock(&LOCK_thd_data);
 }