Patch for BUG#30472: libmysql doesn't reset charset,

insert_id after succ. mysql_change_user() call.

See also WL 4066.
  
This bug reveals two problems:
  - the problem on the client side which was described originally;
  - the problem in protocol / the server side: connection context
    on client and server should be like after mysql_real_connect()
    and be consistent. The server however just resets character
    set variables to the global defaults.

The fix seems to be as follows:
  - extend the protocol so that the client be able to send
    character set information in COM_CHANGE_USER command;
  - change the server so that it understands client character set
    in the command;
  - change the client:
    - reset character set to the default value (which has been
      read from the configuration);
    - send character set in COM_CHANGE_USER command.


client/client_priv.h:
  Declare a function, used in libmysql.c and client.c.
libmysql/libmysql.c:
  1. Reset character set on the client in mysql_change_user().
  2. Send character set to the server in COM_CHANGE_USER command.
mysql-test/t/mysql_client_test.test:
  mysql_client_test.log is used by the test suite.
  
  Use mysql_client_test.out.log to collect mysql_client_test
  real output.
sql/sql_parse.cc:
  Switch character set in COM_CHANGE_USER.
tests/mysql_client_test.c:
  Test case for BUG#30472.

1 files changed, 25 insertions, 1 deletions

diff --git a/libmysql/libmysql.c b/libmysql/libmysql.c
index c8e2d48873f..e2e481fdd21 100644
--- a/libmysql/libmysql.c
+++ b/libmysql/libmysql.c
@@ -685,14 +685,25 @@ int cli_read_change_user_result(MYSQL *mysql, char *buff, const char *passwd)
   return 0;
 }
 
-
 my_bool	STDCALL mysql_change_user(MYSQL *mysql, const char *user,
 				  const char *passwd, const char *db)
 {
   char buff[512],*end=buff;
   int rc;
+  CHARSET_INFO *saved_cs= mysql->charset;
+
   DBUG_ENTER("mysql_change_user");
 
+  /* Get the connection-default character set. */
+
+  if (mysql_init_character_set(mysql))
+  {
+    mysql->charset= saved_cs;
+    DBUG_RETURN(TRUE);
+  }
+
+  /* Use an empty string instead of NULL. */
+
   if (!user)
     user="";
   if (!passwd)
@@ -721,6 +732,14 @@ my_bool	STDCALL mysql_change_user(MYSQL *mysql, const char *user,
   /* Add database if needed */
   end= strmov(end, db ? db : "") + 1;
 
+  /* Add character set number. */
+
+  if (mysql->server_capabilities & CLIENT_SECURE_CONNECTION)
+  {
+    *end= (uchar) mysql->charset->number;
+    ++end;
+  }
+
   /* Write authentication package */
   simple_command(mysql,COM_CHANGE_USER, (uchar*) buff, (ulong) (end-buff), 1);
 
@@ -743,6 +762,11 @@ my_bool	STDCALL mysql_change_user(MYSQL *mysql, const char *user,
     mysql->passwd=my_strdup(passwd,MYF(MY_WME));
     mysql->db=    db ? my_strdup(db,MYF(MY_WME)) : 0;
   }
+  else
+  {
+    mysql->charset= saved_cs;
+  }
+
   DBUG_RETURN(rc);
 }