Bug #51327 MyISAM table is automatically repaired on ALTER

           even if myisam-recover is OFF

The problem was that a corrupted MyISAM table was auto repaired
even if the myisam_recover_options server variable (or the 
myisam_recover option) was set to OFF.

The reason was that the auto_repair() function, which is supposed
to say if auto repair is to be used, did not use the server variable
setting correctly. This bug was a regression introduced by WL#4738.

This patch fixes the problem by making sure auto_repair() returns
FALSE if myisam_recover_options is set to OFF.

Test case added to myisam.test.

mysql-test/r/myisam.result

@@ -2342,3 +2342,36 @@ Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK
 DROP TABLE t1;
 End of 5.1 tests
+#
+# Bug#51327 MyISAM table is automatically repaired on ALTER
+#           even if myisam-recover is OFF
+#
+call mtr.add_suppression("Got an error from thread_id=.*ha_myisam.cc:");
+call mtr.add_suppression("MySQL thread id .*, query id .* localhost.*root Checking table");
+call mtr.add_suppression(" '\..test.t1'");
+# Test that we can exchange a crashed partition with a table
+SELECT @@global.myisam_recover_options;
+@@global.myisam_recover_options
+OFF
+CREATE TABLE t1 (a INT, KEY (a)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1), (2);
+FLUSH TABLES;
+# replacing t.MYI with a corrupt + unclosed one created by doing:
+# 'create table t1 (a int key(a))' head -c1024 t1.MYI > corrupt_t1.MYI 
+CHECK TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	warning	1 client is using or hasn't closed the table properly
+test.t1	check	error	Size of indexfile is: 1024        Should be: 2048
+test.t1	check	warning	Size of datafile is: 14       Should be: 7
+test.t1	check	error	Corrupt
+# Alter table should report error and not auto-repair the table.
+ALTER TABLE t1 ENGINE = MyISAM;
+ERROR HY000: Table 't1' is marked as crashed and should be repaired
+CHECK TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	warning	Table is marked as crashed
+test.t1	check	warning	1 client is using or hasn't closed the table properly
+test.t1	check	error	Size of indexfile is: 1024        Should be: 2048
+test.t1	check	warning	Size of datafile is: 14       Should be: 7
+test.t1	check	error	Corrupt
+DROP TABLE t1;

mysql-test/t/myisam.test

@@ -1591,3 +1591,34 @@ DROP TABLE t1;
 
 --echo End of 5.1 tests
 
+
+--echo #
+--echo # Bug#51327 MyISAM table is automatically repaired on ALTER
+--echo #           even if myisam-recover is OFF
+--echo #
+
+call mtr.add_suppression("Got an error from thread_id=.*ha_myisam.cc:");
+call mtr.add_suppression("MySQL thread id .*, query id .* localhost.*root Checking table");
+call mtr.add_suppression(" '\..test.t1'");
+
+let $MYSQLD_DATADIR = `SELECT @@datadir`;
+--echo # Test that we can exchange a crashed partition with a table
+SELECT @@global.myisam_recover_options;
+CREATE TABLE t1 (a INT, KEY (a)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1), (2);
+FLUSH TABLES;
+
+--echo # replacing t.MYI with a corrupt + unclosed one created by doing:
+--echo # 'create table t1 (a int key(a))' head -c1024 t1.MYI > corrupt_t1.MYI 
+--remove_file $MYSQLD_DATADIR/test/t1.MYI
+--copy_file std_data/corrupt_t1.MYI $MYSQLD_DATADIR/test/t1.MYI
+
+CHECK TABLE t1;
+--echo # Alter table should report error and not auto-repair the table.
+# Remove the path to t1 to prevent platform differences
+--replace_regex /'[^']+'/'t1'/
+--error 145
+ALTER TABLE t1 ENGINE = MyISAM;
+CHECK TABLE t1;
+
+DROP TABLE t1;

storage/myisam/ha_myisam.h

-/* Copyright (C) 2000-2006 MySQL AB
+/* Copyright (C) 2000, 2010 Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -11,7 +11,7 @@
 
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
-   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
 
 #ifdef USE_PRAGMA_INTERFACE
@@ -124,7 +124,7 @@ class ha_myisam: public handler
   int repair(THD* thd, HA_CHECK_OPT* check_opt);
   bool check_and_repair(THD *thd);
   bool is_crashed() const;
-  bool auto_repair() const { return myisam_recover_options != 0; }
+  bool auto_repair() const { return myisam_recover_options != HA_RECOVER_OFF; }
   int optimize(THD* thd, HA_CHECK_OPT* check_opt);
   int assign_to_keycache(THD* thd, HA_CHECK_OPT* check_opt);
   int preload_keys(THD* thd, HA_CHECK_OPT* check_opt);