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, 7 insertions, 10 deletions

diff --git a/sql/sql_audit.h b/sql/sql_audit.h
index 7cb40181bd7..cbc4c7a7232 100644
--- a/sql/sql_audit.h
+++ b/sql/sql_audit.h
@@ -99,32 +99,29 @@ void mysql_audit_general(THD *thd, uint event_subtype,
   {
     time_t time= my_time(0);
     uint msglen= msg ? strlen(msg) : 0;
-    const char *query, *user;
-    uint querylen, userlen;
+    const char *user;
+    uint userlen;
     char user_buff[MAX_USER_HOST_SIZE];
-    CHARSET_INFO *clientcs;
+    CSET_STRING query;
     ha_rows rows;
 
     if (thd)
     {
-      query= thd->query();
-      querylen= thd->query_length();
+      query= thd->query_string;
       user= user_buff;
       userlen= make_user_name(thd, user_buff);
-      clientcs= thd->variables.character_set_client;
       rows= thd->warning_info->current_row_for_warning();
     }
     else
     {
-      query= user= 0;
-      querylen= userlen= 0;
-      clientcs= global_system_variables.character_set_client;
+      user= 0;
+      userlen= 0;
       rows= 0;
     }
 
     mysql_audit_notify(thd, MYSQL_AUDIT_GENERAL_CLASS, event_subtype,
                        error_code, time, user, userlen, msg, msglen,
-                       query, querylen, clientcs, rows);
+                       query.str(), query.length(), query.charset(), rows);
   }
 #endif
 }