BUG#39746 - Debug flag breaks struct definition

            (server crash)

Altering a table with fulltext index[es] which use
pluggable fulltext parser may cause server crash
in debug builds.

The problem was that ALTER TABLE code wrongly assigned
fulltext parser name.

Also fixed that altering a table with fulltext index[es]
leave stale fulltext parser locks, which prevent
fulltext parsers from being uninstalled after
ALTER TABLE.

mysql-test/include/have_simple_parser.inc:
  Added support for testing simple fulltext parser.
mysql-test/mysql-test-run.pl:
  Added support for testing simple fulltext parser.
mysql-test/r/fulltext_plugin.result:
  A test case for BUG#39746.
mysql-test/r/have_simple_parser.require:
  Added support for testing simple fulltext parser.
mysql-test/t/fulltext_plugin-master.opt:
  A test case for BUG#39746.
mysql-test/t/fulltext_plugin.test:
  A test case for BUG#39746.
sql/sql_table.cc:
  Fixed that alter table wrongly assigns fulltext parser
  name. parser_name member is only available during
  table creation. When we open existing table we must
  get parser_name from plugin_ref, which is handled
  by plugin_name() macro.
sql/table.cc:
  Moved code that releases fulltext parsers into
  free_table_share(). This fixes stale fulltext parser
  locks set by ALTER TABLE, which are preventing fulltext
  parsers from being uninstalled.

mysql-test/include/have_simple_parser.inc

+#
+# Check if server has support for loading udf's
+# i.e it will support dlopen
+#
+--require r/have_dynamic_loading.require
+disable_query_log;
+show variables like 'have_dynamic_loading';
+enable_query_log;
+
+#
+# Check if the variable SIMPLE_PARSER is set
+#
+--require r/have_simple_parser.require
+disable_query_log;
+eval select LENGTH('$SIMPLE_PARSER') > 0 as 'have_simple_parser';
+enable_query_log;

mysql-test/mysql-test-run.pl

@@ -163,6 +163,7 @@ our $exe_my_print_defaults;
 our $exe_perror;
 our $lib_udf_example;
 our $lib_example_plugin;
+our $lib_simple_parser;
 our $exe_libtool;
 
 our $opt_bench= 0;
@@ -1717,6 +1718,10 @@ sub executable_setup () {
       mtr_file_exists(vs_config_dirs('storage/example', 'ha_example.dll'),
                       "$glob_basedir/storage/example/.libs/ha_example.so",);
 
+    # Look for the simple_parser library
+    $lib_simple_parser=
+      mtr_file_exists(vs_config_dirs('plugin/fulltext', 'mypluglib.dll'),
+                      "$glob_basedir/plugin/fulltext/.libs/mypluglib.so",);
   }
 
   # Look for mysqltest executable
@@ -2199,6 +2204,14 @@ sub environment_setup () {
   $ENV{'EXAMPLE_PLUGIN_OPT'}=
     ($lib_example_plugin ? "--plugin_dir=" . dirname($lib_example_plugin) : "");
 
+  # ----------------------------------------------------
+  # Add the path where mysqld will find mypluglib.so
+  # ----------------------------------------------------
+  $ENV{'SIMPLE_PARSER'}=
+    ($lib_simple_parser ? basename($lib_simple_parser) : "");
+  $ENV{'SIMPLE_PARSER_OPT'}=
+    ($lib_simple_parser ? "--plugin_dir=" . dirname($lib_simple_parser) : "");
+
   # ----------------------------------------------------
   # Setup env so childs can execute myisampack and myisamchk
   # ----------------------------------------------------

mysql-test/r/fulltext_plugin.result

+INSTALL PLUGIN simple_parser SONAME 'mypluglib.so';
+CREATE TABLE t1(a TEXT, b TEXT, FULLTEXT(a) WITH PARSER simple_parser);
+ALTER TABLE t1 ADD FULLTEXT(b) WITH PARSER simple_parser;
+DROP TABLE t1;
+UNINSTALL PLUGIN simple_parser;

mysql-test/r/have_simple_parser.require

+have_simple_parser
+1

mysql-test/t/fulltext_plugin-master.opt

+$SIMPLE_PARSER_OPT

mysql-test/t/fulltext_plugin.test

+--source include/have_simple_parser.inc
+
+#
+# BUG#39746 - Debug flag breaks struct definition (server crash)
+#
+INSTALL PLUGIN simple_parser SONAME 'mypluglib.so';
+CREATE TABLE t1(a TEXT, b TEXT, FULLTEXT(a) WITH PARSER simple_parser);
+ALTER TABLE t1 ADD FULLTEXT(b) WITH PARSER simple_parser;
+DROP TABLE t1;
+UNINSTALL PLUGIN simple_parser;

sql/sql_table.cc

@@ -5870,7 +5870,7 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
       if (key_info->flags & HA_USES_BLOCK_SIZE)
         key_create_info.block_size= key_info->block_size;
       if (key_info->flags & HA_USES_PARSER)
-        key_create_info.parser_name= *key_info->parser_name;
+        key_create_info.parser_name= *plugin_name(key_info->parser);
 
       if (key_info->flags & HA_SPATIAL)
         key_type= Key::SPATIAL;

sql/table.cc

@@ -400,6 +400,8 @@ void init_tmp_table_share(THD *thd, TABLE_SHARE *share, const char *key,
 void free_table_share(TABLE_SHARE *share)
 {
   MEM_ROOT mem_root;
+  uint idx;
+  KEY *key_info;
   DBUG_ENTER("free_table_share");
   DBUG_PRINT("enter", ("table: %s.%s", share->db.str, share->table_name.str));
   DBUG_ASSERT(share->ref_count == 0);
@@ -426,6 +428,16 @@ void free_table_share(TABLE_SHARE *share)
   plugin_unlock(NULL, share->db_plugin);
   share->db_plugin= NULL;
 
+  /* Release fulltext parsers */
+  key_info= share->key_info;
+  for (idx= share->keys; idx; idx--, key_info++)
+  {
+    if (key_info->flags & HA_USES_PARSER)
+    {
+      plugin_unlock(NULL, key_info->parser);
+      key_info->flags= 0;
+    }
+  }
   /* We must copy mem_root from share because share is allocated through it */
   memcpy((char*) &mem_root, (char*) &share->mem_root, sizeof(mem_root));
   free_root(&mem_root, MYF(0));                 // Free's share
@@ -1943,22 +1955,11 @@ int open_table_from_share(THD *thd, TABLE_SHARE *share, const char *alias,
 int closefrm(register TABLE *table, bool free_share)
 {
   int error=0;
-  uint idx;
-  KEY *key_info;
   DBUG_ENTER("closefrm");
   DBUG_PRINT("enter", ("table: 0x%lx", (long) table));
 
   if (table->db_stat)
     error=table->file->close();
-  key_info= table->key_info;
-  for (idx= table->s->keys; idx; idx--, key_info++)
-  {
-    if (key_info->flags & HA_USES_PARSER)
-    {
-      plugin_unlock(NULL, key_info->parser);
-      key_info->flags= 0;
-    }
-  }
   my_free((char*) table->alias, MYF(MY_ALLOW_ZERO_PTR));
   table->alias= 0;
   if (table->field)