MDEV-5996 - fix odd behaviour of some combinations of table and database names

storage/oqgraph/ha_oqgraph.cc

@@ -557,9 +557,11 @@ int ha_oqgraph::open(const char *name, int mode, uint test_if_locked)
   size_t tlen= strlen(options->table_name);
   size_t plen= (int)(p - name) + tlen + 1;
 
-  share->path.str= (char*)alloc_root(&share->mem_root, plen);
+  share->path.str= (char*)alloc_root(&share->mem_root, plen + 1); // MDEV-5996 space for trailing zero
+  // it seems there was a misunderstanding of why there is a separate length field in the String object
   strmov(strnmov(share->path.str, name, (int)(p - name) + 1), options->table_name);
 
+  share->path.str[plen] = 0; // MDEV-5996 Make sure the pointer is zero terminated.  I really think this needs refactoring, soon...
   share->normalized_path.str= share->path.str;
   share->path.length= share->normalized_path.length= plen;
 

storage/oqgraph/mysql-test/oqgraph/regression_mdev5996.inc

+# Regression test for https://mariadb.atlassian.net/browse/MDEV-5996
+--echo Performing OQGraph regression test mdev5996 - using db=`$oqgraph_database_name`, table=`$oqgraph_table_name`
+
+--disable_warnings
+use test;
+if ($oqgraph_database_name) {
+  eval drop database if exists `$oqgraph_database_name` ;
+  eval create database `$oqgraph_database_name` ;
+  eval use `$oqgraph_database_name` ;
+}
+eval drop table if exists `$oqgraph_table_name` ;
+drop table if exists vvvvvvv_hhhhhhh;
+--enable_warnings
+
+eval CREATE TABLE `$oqgraph_table_name` (
+  `version` varchar(10) NOT NULL,
+  `updateJSON` mediumtext,
+  `prevVersion` varchar(10) NOT NULL,
+  `nodeID` bigint(20) unsigned NOT NULL DEFAULT '0',
+  `prevNodeID` bigint(20) unsigned NOT NULL DEFAULT '0',
+  PRIMARY KEY (`prevNodeID`,`nodeID`),
+  KEY `prevVersion` (`prevVersion`) USING BTREE,
+  KEY `version` (`version`) USING BTREE,
+  KEY `nodeID` (`nodeID`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8;
+
+eval insert into `$oqgraph_table_name` values ( 'x', 'y', 'z', 0, 0);
+
+eval select * from `$oqgraph_table_name`;
+
+eval CREATE TABLE IF NOT EXISTS vvvvvvv_hhhhhhh (
+  latch VARCHAR(32) NULL,
+  origid BIGINT UNSIGNED NULL,
+  destid BIGINT UNSIGNED NULL,
+  weight DOUBLE NULL,
+  seq BIGINT UNSIGNED NULL,
+  linkid BIGINT UNSIGNED NULL,
+  KEY (latch, origid, destid) USING HASH,
+  KEY (latch, destid, origid) USING HASH
+) ENGINE=OQGRAPH
+  data_table='$oqgraph_table_name'
+  origid='prevNodeID'
+ destid='nodeID';
+
+select * from vvvvvvv_hhhhhhh;
+
+eval drop table if exists `$oqgraph_table_name`;
+drop table if exists vvvvvvv_hhhhhhh;
+
+if ($oqgraph_database_name) {
+  eval drop database if exists `$oqgraph_database_name`;
+}
+

storage/oqgraph/mysql-test/oqgraph/regression_mdev5996.test

+# Regression test for https://mariadb.atlassian.net/browse/MDEV-5996
+# MidSchipDB_unstable
+--let $oqgraph_table_name= 999999999
+
+--let $oqgraph_database_name= 
+--source regression_mdev5996.inc
+
+--let $oqgraph_database_name= 1
+--source regression_mdev5996.inc
+
+# Various cases - although actual bug was a broken zero termination
+# name of backing store shorter, same and longer than table
+
+--let $oqgraph_database_name= 1112222233_4444444
+--source regression_mdev5996.inc
+
+--let $oqgraph_database_name= 1112222233_44444444
+--source regression_mdev5996.inc
+
+--let $oqgraph_database_name= 1112222233_444444444
+--source regression_mdev5996.inc
+
+--let $oqgraph_table_name= 99999999
+--source regression_mdev5996.inc
+
+--let $oqgraph_table_name= 9999999999
+--source regression_mdev5996.inc
+
+# Fails:
+
+# 1/9999
+# test/99999999
+# 1112222233_444444444/999999999