Bug#42610 Dynamic plugin broken in 5.1.31

added ignore-builtin-innodb option which disabled
initialization of builtin InnoDB plugin

mysql-test/r/innodb_ignore_builtin.result:
  test case
mysql-test/t/innodb_ignore_builtin-master.opt:
  test case
mysql-test/t/innodb_ignore_builtin.test:
  test case
sql/mysql_priv.h:
  added ignore-builtin-innodb option which disabled
  initialization of builtin InnoDB plugin
sql/mysqld.cc:
  added ignore-builtin-innodb option which disabled
  initialization of builtin InnoDB plugin
sql/set_var.cc:
  added ignore-builtin-innodb option which disabled
  initialization of builtin InnoDB plugin
sql/sql_plugin.cc:
  added ignore-builtin-innodb option which disabled
  initialization of builtin InnoDB plugin

mysql-test/r/innodb_ignore_builtin.result

+show variables like 'ignore_builtin_innodb';
+Variable_name	Value
+ignore_builtin_innodb	ON
+select PLUGIN_NAME from information_schema.plugins
+where PLUGIN_NAME = "InnoDb";
+PLUGIN_NAME
+select ENGINE from information_schema.engines
+where ENGINE = "InnoDB";
+ENGINE

mysql-test/t/innodb_ignore_builtin-master.opt

+--ignore_builtin_innodb

mysql-test/t/innodb_ignore_builtin.test

+#
+# Bug #42610:  Dynamic plugin broken in 5.1.31
+#
+show variables like 'ignore_builtin_innodb';
+select PLUGIN_NAME from information_schema.plugins
+where PLUGIN_NAME = "InnoDb";
+select ENGINE from information_schema.engines
+where ENGINE = "InnoDB";

sql/mysql_priv.h

@@ -1953,6 +1953,7 @@ extern my_bool opt_log, opt_slow_log;
 extern ulong log_output_options;
 extern my_bool opt_log_queries_not_using_indexes;
 extern bool opt_disable_networking, opt_skip_show_db;
+extern bool opt_ignore_builtin_innodb;
 extern my_bool opt_character_set_client_handshake;
 extern bool volatile abort_loop, shutdown_in_progress;
 extern uint volatile thread_count, thread_running, global_read_lock;

sql/mysqld.cc

@@ -378,7 +378,7 @@ static pthread_cond_t COND_thread_cache, COND_flush_thread_cache;
 
 /* Global variables */
 
-bool opt_update_log, opt_bin_log;
+bool opt_update_log, opt_bin_log, opt_ignore_builtin_innodb= 0;
 my_bool opt_log, opt_slow_log;
 ulong log_output_options;
 my_bool opt_log_queries_not_using_indexes= 0;
@@ -5585,7 +5585,8 @@ enum options_mysqld
   OPT_OLD_MODE,
   OPT_SLAVE_EXEC_MODE,
   OPT_GENERAL_LOG_FILE,
-  OPT_SLOW_QUERY_LOG_FILE
+  OPT_SLOW_QUERY_LOG_FILE,
+  OPT_IGNORE_BUILTIN_INNODB
 };
 
 
@@ -5791,6 +5792,9 @@ Disable with --skip-large-pages.",
    (uchar**) &opt_large_pages, (uchar**) &opt_large_pages, 0, GET_BOOL, NO_ARG, 0, 0, 0,
    0, 0, 0},
 #endif
+  {"ignore-builtin-innodb", OPT_IGNORE_BUILTIN_INNODB ,
+   "Disable initialization of builtin InnoDB plugin",
+   0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"init-connect", OPT_INIT_CONNECT, "Command(s) that are executed for each new connection",
    (uchar**) &opt_init_connect, (uchar**) &opt_init_connect, 0, GET_STR_ALLOC,
    REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
@@ -7484,6 +7488,7 @@ static int mysql_init_variables(void)
   log_output_options= find_bit_type(log_output_str, &log_output_typelib);
   opt_bin_log= 0;
   opt_disable_networking= opt_skip_show_db=0;
+  opt_ignore_builtin_innodb= 0;
   opt_logname= opt_update_logname= opt_binlog_index_name= opt_slow_logname= 0;
   opt_tc_log_file= (char *)"tc.log";      // no hostname in tc_log file name !
   opt_secure_auth= 0;
@@ -7781,6 +7786,9 @@ mysqld_get_one_option(int optid,
   case (int) OPT_BIG_TABLES:
     thd_startup_options|=OPTION_BIG_TABLES;
     break;
+  case (int) OPT_IGNORE_BUILTIN_INNODB:
+    opt_ignore_builtin_innodb= 1;
+    break;
   case (int) OPT_ISAM_LOG:
     opt_myisam_log=1;
     break;

sql/set_var.cc

@@ -275,6 +275,11 @@ static sys_var_const    sys_ft_query_expansion_limit(&vars,
 static sys_var_const    sys_ft_stopword_file(&vars, "ft_stopword_file",
                                              OPT_GLOBAL, SHOW_CHAR_PTR,
                                              (uchar*) &ft_stopword_file);
+
+static sys_var_const    sys_ignore_builtin_innodb(&vars, "ignore_builtin_innodb",
+                                                  OPT_GLOBAL, SHOW_BOOL,
+                                                  (uchar*) &opt_ignore_builtin_innodb);
+
 sys_var_str             sys_init_connect(&vars, "init_connect", 0,
                                          sys_update_init_connect,
                                          sys_default_init_connect,0);

sql/sql_plugin.cc

@@ -1138,6 +1138,9 @@ int plugin_init(int *argc, char **argv, int flags)
   {
     for (plugin= *builtins; plugin->info; plugin++)
     {
+      if (opt_ignore_builtin_innodb &&
+          !my_strcasecmp(&my_charset_latin1, plugin->name, "InnoDB"))
+          continue;
       /* by default, ndbcluster and federated are disabled */
       def_enabled=
         my_strcasecmp(&my_charset_latin1, plugin->name, "NDBCLUSTER") != 0 &&