Bug#31608 missing mysqltest change_user command

The problem is that currently there is no way to test the behavior
of the mysql_change_user() function using the mysqltest suite because
there is no internal command for it.

The solution is to introduce a change_user command that can be used
to test aspects of the MySQL client function mysql_change_user().

client/mysqltest.c

@@ -263,7 +263,7 @@ enum enum_commands {
   Q_REPLACE_REGEX, Q_REMOVE_FILE, Q_FILE_EXIST,
   Q_WRITE_FILE, Q_COPY_FILE, Q_PERL, Q_DIE, Q_EXIT, Q_SKIP,
   Q_CHMOD_FILE, Q_APPEND_FILE, Q_CAT_FILE, Q_DIFF_FILES,
-  Q_SEND_QUIT,
+  Q_SEND_QUIT, Q_CHANGE_USER,
 
   Q_UNKNOWN,			       /* Unknown command.   */
   Q_COMMENT,			       /* Comments, ignored. */
@@ -352,6 +352,7 @@ const char *command_names[]=
   "cat_file",
   "diff_files",
   "send_quit",
+  "change_user",
   0
 };
 
@@ -3028,6 +3029,63 @@ void do_send_quit(struct st_command *command)
 }
 
 
+/*
+  SYNOPSIS
+  do_change_user
+  command       called command
+
+  DESCRIPTION
+  change_user [<user>], [<passwd>], [<db>]
+  <user> - user to change to
+  <passwd> - user password
+  <db> - default database
+
+  Changes the user and causes the database specified by db to become
+  the default (current) database for the the current connection.
+
+*/
+
+void do_change_user(struct st_command *command)
+{
+  MYSQL *mysql = &cur_con->mysql;
+  /* static keyword to make the NetWare compiler happy. */
+  static DYNAMIC_STRING ds_user, ds_passwd, ds_db;
+  const struct command_arg change_user_args[] = {
+    { "user", ARG_STRING, FALSE, &ds_user, "User to connect as" },
+    { "password", ARG_STRING, FALSE, &ds_passwd, "Password used when connecting" },
+    { "database", ARG_STRING, FALSE, &ds_db, "Database to select after connect" },
+  };
+
+  DBUG_ENTER("do_change_user");
+
+  check_command_args(command, command->first_argument,
+                     change_user_args,
+                     sizeof(change_user_args)/sizeof(struct command_arg),
+                     ',');
+
+  if (!ds_user.length)
+    dynstr_set(&ds_user, mysql->user);
+
+  if (!ds_passwd.length)
+    dynstr_set(&ds_passwd, mysql->passwd);
+
+  if (!ds_db.length)
+    dynstr_set(&ds_db, mysql->db);
+
+  DBUG_PRINT("info",("connection: '%s' user: '%s' password: '%s' database: '%s'",
+                      cur_con->name, ds_user.str, ds_passwd.str, ds_db.str));
+
+  if (mysql_change_user(mysql, ds_user.str, ds_passwd.str, ds_db.str))
+    die("change user failed: %s", mysql_error(mysql));
+
+  dynstr_free(&ds_user);
+  dynstr_free(&ds_passwd);
+  dynstr_free(&ds_db);
+
+  DBUG_VOID_RETURN;
+}
+
+
 /*
   SYNOPSIS
   do_perl
@@ -6836,6 +6894,7 @@ int main(int argc, char **argv)
       case Q_APPEND_FILE: do_append_file(command); break;
       case Q_DIFF_FILES: do_diff_files(command); break;
       case Q_SEND_QUIT: do_send_quit(command); break;
+      case Q_CHANGE_USER: do_change_user(command); break;
       case Q_CAT_FILE: do_cat_file(command); break;
       case Q_COPY_FILE: do_copy_file(command); break;
       case Q_CHMOD_FILE: do_chmod_file(command); break;

mysql-test/r/change_user.result

+Bug#20023
+SELECT @@session.sql_big_selects;
+@@session.sql_big_selects
+1
+SELECT @@global.max_join_size;
+@@global.max_join_size
+-1
+change_user
+SELECT @@session.sql_big_selects;
+@@session.sql_big_selects
+1
+SELECT @@global.max_join_size;
+@@global.max_join_size
+-1
+SET @@global.max_join_size = 10000;
+SET @@session.max_join_size = default;
+change_user
+SELECT @@session.sql_big_selects;
+@@session.sql_big_selects
+0
+SET @@global.max_join_size = -1;
+SET @@session.max_join_size = default;
+change_user
+SELECT @@session.sql_big_selects;
+@@session.sql_big_selects
+1
+Bug#31418
+SELECT IS_FREE_LOCK('bug31418');
+IS_FREE_LOCK('bug31418')
+1
+SELECT IS_USED_LOCK('bug31418');
+IS_USED_LOCK('bug31418')
+NULL
+SELECT GET_LOCK('bug31418', 1);
+GET_LOCK('bug31418', 1)
+1
+SELECT IS_USED_LOCK('bug31418');
+IS_USED_LOCK('bug31418')
+1
+change_user
+SELECT IS_FREE_LOCK('bug31418');
+IS_FREE_LOCK('bug31418')
+1
+SELECT IS_USED_LOCK('bug31418');
+IS_USED_LOCK('bug31418')
+NULL

mysql-test/r/mysqltest.result

@@ -722,4 +722,7 @@ a	int(11)	YES		NULL
 b	varchar(255)	YES		NULL	
 c	datetime	YES		NULL	
 drop table t1;
+mysqltest: At line 1: change user failed: Unknown database 'inexistent'
+mysqltest: At line 1: change user failed: Access denied for user 'inexistent'@'localhost' (using password: NO)
+mysqltest: At line 1: change user failed: Access denied for user 'root'@'localhost' (using password: YES)
 End of tests

mysql-test/t/change_user.test

+#
+# Bug#20023 mysql_change_user() resets the value of SQL_BIG_SELECTS
+#
+
+--echo Bug#20023
+SELECT @@session.sql_big_selects;
+SELECT @@global.max_join_size;
+--echo change_user
+--change_user
+SELECT @@session.sql_big_selects;
+SELECT @@global.max_join_size;
+SET @@global.max_join_size = 10000;
+SET @@session.max_join_size = default;
+--echo change_user
+--change_user
+SELECT @@session.sql_big_selects;
+SET @@global.max_join_size = -1;
+SET @@session.max_join_size = default;
+--echo change_user
+--change_user
+SELECT @@session.sql_big_selects;
+
+#
+# Bug#31418 User locks misfunctioning after mysql_change_user()
+#
+
+--echo Bug#31418
+SELECT IS_FREE_LOCK('bug31418');
+SELECT IS_USED_LOCK('bug31418');
+SELECT GET_LOCK('bug31418', 1);
+SELECT IS_USED_LOCK('bug31418');
+--echo change_user
+--change_user
+SELECT IS_FREE_LOCK('bug31418');
+SELECT IS_USED_LOCK('bug31418');

mysql-test/t/mysqltest.test

@@ -2080,5 +2080,23 @@ eval $show_statement;
 
 drop table t1;
 
+# ----------------------------------------------------------------------------
+# Test change_user command
+# ----------------------------------------------------------------------------
+
+--error 1
+--exec echo "--change_user root,,inexistent" | $MYSQL_TEST 2>&1
+
+--error 1
+--exec echo "--change_user inexistent,,test" | $MYSQL_TEST 2>&1
+
+--error 1
+--exec echo "--change_user root,inexistent,test" | $MYSQL_TEST 2>&1
+
+--change_user
+--change_user root
+--change_user root,,
+--change_user root,,test
+
 --echo End of tests