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, 2 insertions, 5 deletions

diff --git a/sql/sp_head.cc b/sql/sp_head.cc
index 01c11d35a62..de20b9547c5 100644
--- a/sql/sp_head.cc
+++ b/sql/sp_head.cc
@@ -3065,8 +3065,6 @@ int sp_instr::exec_core(THD *thd, uint *nextp)
 int
 sp_instr_stmt::execute(THD *thd, uint *nextp)
 {
-  char *query;
-  uint32 query_length;
   int res;
   DBUG_ENTER("sp_instr_stmt::execute");
   DBUG_PRINT("info", ("command: %d", m_lex_keeper.sql_command()));
@@ -3074,8 +3072,7 @@ sp_instr_stmt::execute(THD *thd, uint *nextp)
   if (check_stack_overrun(thd, STACK_MIN_SIZE, (uchar*)&res))
     DBUG_RETURN(TRUE);
 
-  query= thd->query();
-  query_length= thd->query_length();
+  const CSET_STRING query_backup= thd->query_string;
 #if defined(ENABLED_PROFILING)
   /* This s-p instr is profilable and will be captured. */
   thd->profiling.set_query_source(m_query.str, m_query.length);
@@ -3105,7 +3102,7 @@ sp_instr_stmt::execute(THD *thd, uint *nextp)
     }
     else
       *nextp= m_ip+1;
-    thd->set_query(query, query_length);
+    thd->set_query(query_backup);
     thd->query_name_consts= 0;
 
     if (!thd->is_error())