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.

1 files changed, 33 insertions, 0 deletions

diff --git a/mysql-test/r/myisam.result b/mysql-test/r/myisam.result
index df53b1d1480..73cf5df0304 100644
--- a/mysql-test/r/myisam.result
+++ b/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;