BUG#16217 forced to introduce a separate mysql client command to adopt its

internal charset to one associated with currently being handled query. 
To note such a query can come from interactive client either.

There was a discussion within replication team and Monty who's suggestion won.
It avoids straightforward parsing of all `set' queries that could affect client side 
character set. 
According to the idea, mysql client does not parse `set' queries but rather cares of
`charset new_cs_name' command.
This command is generated by mysqlbinlog in form of exclaiming comment (Lars' suggestion)
so that enlightened clients like `mysql' knows what to do with it.

Interactive human can switch between many multi-byte charsets during the session 
providing the command explicitly. 
To note that setting new internal mysql's charset does not
trigger sending any `SET' sql statement to the server. 

client/mysql.cc

@@ -194,7 +194,7 @@ static int com_quit(String *str,char*),
 	   com_connect(String *str,char*), com_status(String *str,char*),
 	   com_use(String *str,char*), com_source(String *str, char*),
 	   com_rehash(String *str, char*), com_tee(String *str, char*),
-           com_notee(String *str, char*),
+           com_notee(String *str, char*), com_charset(String *str,char*),
            com_prompt(String *str, char*), com_delimiter(String *str, char*),
      com_warnings(String *str, char*), com_nowarnings(String *str, char*);
 
@@ -268,6 +268,8 @@ static COMMANDS commands[] = {
     "Set outfile [to_outfile]. Append everything into given outfile." },
   { "use",    'u', com_use,    1,
     "Use another database. Takes database name as argument." },
+  { "charset",    'C', com_charset,    1,
+    "Switch to another charset. Might be needed for processing binlog with multi-byte charsets." },
   { "warnings", 'W', com_warnings,  0,
     "Show warnings after every statement." },
   { "nowarning", 'w', com_nowarnings, 0,
@@ -1909,6 +1911,28 @@ com_clear(String *buffer,char *line __attribute__((unused)))
   return 0;
 }
 
+	/* ARGSUSED */
+static int
+com_charset(String *buffer __attribute__((unused)), char *line)
+{
+  char buff[256], *param;
+  CHARSET_INFO * new_cs;
+  strmake(buff, line, sizeof(buff) - 1);
+  param= get_arg(buff, 0);
+  if (!param || !*param)
+  {
+    return put_info("Usage: \\C char_setname | charset charset_name", 
+		    INFO_ERROR, 0);
+  }
+  new_cs= get_charset_by_csname(param, MY_CS_PRIMARY, MYF(MY_WME));
+  if (new_cs)
+  {
+    charset_info= new_cs;
+    put_info("Charset changed", INFO_INFO);
+  }
+  else put_info("Charset is not found", INFO_INFO);
+  return 0;
+}
 
 /*
   Execute command

mysql-test/r/ctype_ucs_binlog.result

@@ -15,6 +15,7 @@ use test;
 SET TIMESTAMP=10000;
 SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=1, @@session.unique_checks=1;
 SET @@session.sql_mode=0;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8;
 insert into t2 values (@v);
 # End of log file

mysql-test/r/mysql.result

@@ -59,3 +59,13 @@ database()
 test
 unlock tables;
 drop table t1;
+ソ
+ソ
+c_cp932
+ソ
+ソ
+ソ
+ソ
+ソ
+ソ
+ソ

mysql-test/r/mysqlbinlog.result

@@ -20,6 +20,7 @@ use test;
 SET TIMESTAMP=1000000000;
 SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=1, @@session.unique_checks=1;
 SET @@session.sql_mode=0;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8;
 drop table if exists t1,t2;
 SET TIMESTAMP=1000000000;
@@ -50,6 +51,7 @@ use test;
 SET TIMESTAMP=1000000000;
 SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=1, @@session.unique_checks=1;
 SET @@session.sql_mode=0;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8;
 insert into t1 values ("Alas");
 # End of log file
@@ -72,6 +74,7 @@ use test;
 SET TIMESTAMP=1000000000;
 SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=1, @@session.unique_checks=1;
 SET @@session.sql_mode=0;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8;
 insert into t1 values ("Alas");
 # End of log file
@@ -86,6 +89,7 @@ use test;
 SET TIMESTAMP=1000000000;
 SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=1, @@session.unique_checks=1;
 SET @@session.sql_mode=0;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8;
 drop table if exists t1,t2;
 SET TIMESTAMP=1000000000;
@@ -116,6 +120,7 @@ use test;
 SET TIMESTAMP=1000000000;
 SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=1, @@session.unique_checks=1;
 SET @@session.sql_mode=0;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8;
 insert into t1 values ("Alas");
 # End of log file
@@ -138,6 +143,7 @@ use test;
 SET TIMESTAMP=1000000000;
 SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=1, @@session.unique_checks=1;
 SET @@session.sql_mode=0;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8;
 insert into t1 values ("Alas");
 # End of log file
@@ -166,4 +172,21 @@ insert t1 values (1);
 # End of log file
 ROLLBACK /* added by mysqlbinlog */;
 /*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
-drop table t1, t2;
+flush logs;
+create table t3 (f text character set utf8);
+create table t4 (f text character set cp932);
+flush logs;
+rename table t3 to t03, t4 to t04;
+select HEX(f) from t03;
+HEX(f)
+E382BD
+select HEX(f) from t3;
+HEX(f)
+E382BD
+select HEX(f) from t04;
+HEX(f)
+835C
+select HEX(f) from t4;
+HEX(f)
+835C
+drop table t1, t2, t03, t04, t3, t4;

mysql-test/r/rpl_charset.result

@@ -180,6 +180,7 @@ ROLLBACK;
 SET TIMESTAMP=1000000000;
 SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=1, @@session.unique_checks=1;
 SET @@session.sql_mode=0;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8;
 drop database if exists mysqltest2;
 SET TIMESTAMP=1000000000;
@@ -187,9 +188,11 @@ drop database if exists mysqltest3;
 SET TIMESTAMP=1000000000;
 create database mysqltest2 character set latin2;
 SET TIMESTAMP=1000000000;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=30;
 create database mysqltest3;
 SET TIMESTAMP=1000000000;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=64;
 drop database mysqltest3;
 SET TIMESTAMP=1000000000;
@@ -199,6 +202,7 @@ SET TIMESTAMP=1000000000;
 create table t1 (a int auto_increment primary key, b varchar(100));
 SET INSERT_ID=1;
 SET TIMESTAMP=1000000000;
+/*!\C cp850 */;
 SET @@session.character_set_client=4,@@session.collation_connection=27,@@session.collation_server=64;
 insert into t1 (b) values(@@character_set_server);
 SET INSERT_ID=2;
@@ -214,6 +218,7 @@ SET INSERT_ID=5;
 SET TIMESTAMP=1000000000;
 insert into t1 (b) values(@@collation_connection);
 SET TIMESTAMP=1000000000;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=5,@@session.collation_server=64;
 truncate table t1;
 SET INSERT_ID=1;
@@ -224,6 +229,7 @@ SET TIMESTAMP=1000000000;
 insert into t1 (b) values(LEAST("Mller","Muffler"));
 SET INSERT_ID=3;
 SET TIMESTAMP=1000000000;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=31,@@session.collation_server=64;
 insert into t1 (b) values(@@collation_connection);
 SET INSERT_ID=4;
@@ -241,9 +247,11 @@ SET TIMESTAMP=1000000000;
 drop database mysqltest3;
 use test;
 SET TIMESTAMP=1000000000;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=30;
 CREATE TABLE t1 (c1 VARBINARY(255), c2 VARBINARY(255));
 SET TIMESTAMP=1000000000;
+/*!\C koi8r */;
 SET @@session.character_set_client=7,@@session.collation_connection=51,@@session.collation_server=30;
 INSERT INTO t1 (c1, c2) VALUES (',  ',',  ');
 # End of log file

mysql-test/r/rpl_timezone.result

@@ -48,6 +48,7 @@ use test;
 SET TIMESTAMP=100000000;
 SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=1, @@session.unique_checks=1;
 SET @@session.sql_mode=0;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8;
 create table t1 (t timestamp);
 SET TIMESTAMP=100000000;

mysql-test/r/user_var-binlog.result

@@ -21,6 +21,7 @@ use test;
 SET TIMESTAMP=10000;
 SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=1, @@session.unique_checks=1;
 SET @@session.sql_mode=0;
+/*!\C latin1 */;
 SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8;
 INSERT INTO t1 VALUES(@`a b`);
 SET @`var1`:=_latin1 0x273B616161 COLLATE `latin1_swedish_ci`;

mysql-test/t/mysql.test

@@ -41,3 +41,16 @@ lock tables t1 write;
 unlock tables;
 drop table t1;
 
+#
+# BUG#16217 - MySQL client misinterpretes multi-byte char as escape `\' 
+#
+
+# new command \C or charset
+--exec $MYSQL --default-character-set=utf8 test -e "\C cp932 \g"
+--exec $MYSQL --default-character-set=cp932 test -e "charset utf8;"
+
+# its usage to switch internally in mysql to requested charset
+--exec $MYSQL --default-character-set=utf8 test -e "charset cp932; set @@session.character_set_client= cp932; select '\'; create table t1 (c_cp932 TEXT CHARACTER SET cp932); insert into t1 values('\'); select * from t1;  drop table t1;"
+--exec $MYSQL --default-character-set=utf8 test -e "charset cp932; set character_set_client= cp932; select '\'"
+--exec $MYSQL --default-character-set=utf8 test -e "/*charset cp932 */; set character_set_client= cp932; select '\'"
+--exec $MYSQL --default-character-set=utf8 test -e "/*!\C cp932 */; set character_set_client= cp932; select '\'"

mysql-test/t/mysqlbinlog.test

@@ -107,7 +107,24 @@ select "--- reading stdin --" as "";
 --replace_result $MYSQL_TEST_DIR MYSQL_TEST_DIR
 --exec $MYSQL_BINLOG --short-form --position=79 - < $MYSQL_TEST_DIR/std_data/trunc_binlog.000001
 
+# Bug#16217 (mysql client did not know how not switch its internal charset)
+flush logs;
+create table t3 (f text character set utf8);
+create table t4 (f text character set cp932); 
+--exec $MYSQL --default-character-set=utf8 test -e "insert into t3 values(_utf8'ソ')"
+--exec $MYSQL --default-character-set=cp932 test -e "insert into t4 values(_cp932'\');"
+flush logs;
+rename table t3 to t03, t4 to t04;
+--exec $MYSQL_BINLOG --short-form $MYSQLTEST_VARDIR/log/master-bin.000004 | $MYSQL --default-character-set=utf8
+# original and recovered data must be equal
+select HEX(f) from t03;
+select HEX(f) from t3;
+select HEX(f) from t04;
+select HEX(f) from t4;
+
+
+
 # clean up
-drop table t1, t2;
+drop table t1, t2, t03, t04, t3, t4; 
 
 # End of 4.1 tests

sql/log_event.cc

@@ -1551,6 +1551,11 @@ void Query_log_event::print_query_header(FILE* file,
     }
     if (unlikely(bcmp(print_event_info->charset, charset, 6)))
     {
+      CHARSET_INFO *cs_info= get_charset(uint2korr(charset), MYF(MY_WME));
+      if (cs_info)
+      {
+        fprintf(file, "/*!\\C %s */;\n", cs_info->csname); /* for mysql client */
+      }
       fprintf(file,"SET "
               "@@session.character_set_client=%d,"
               "@@session.collation_connection=%d,"