Bug#19027 MySQL 5.0 starts even with Fatal InnoDB errors

It is not possible to prevent the server from starting if a mandatory
built-in plugin fails to start. This can in some cases lead to data
corruption when the old table name space suddenly is used by a different
storage engine.

A boolean command line option in the form of --foobar is automatically
created for every existing plugin "foobar". By changing this command line
option from a boolean to a tristate { OFF, ON, FORCE } it is possible to
specify the plugin loading policy for each plugin.

The behavior is specified as follows:
   OFF   = Disable the plugin and start the server
   ON    = Enable the plugin and start the server even if an error occurrs
           during plugin initialization.
   FORCE = Enable the plugin but don't start the server if an error occurrs
           during plugin initialization.


mysql-test/lib/mtr_cases.pm:
  * Changed --<pluginname> from a boolean to a tristate.
mysys/my_getopt.c:
  * Changed --<pluginname> from boolean to tristate. Optional arguments
    must still work for tristates. It is praxis that disable means value 0
    and enable is value 1. Since plugin name is the only tristate with
    optional arguments this principle will still hold.
sql/sql_plugin.cc:
  * Changed --<pluginname> option from a boolean type to a tristate.
    - FORCE will now terminate the server if the plugin fails to
      initialize properly.
  * Refactored prototypes for test_plugin_options() and construct_options()
    to get rid of the 'enable' value pointer.
  * Cleaned up code related to option name constructing.
  * Added documentation
sql/sql_plugin.h:
  * Introduced new member to st_plugin_int structure.

1 files changed, 1 insertions, 0 deletions

diff --git a/sql/sql_plugin.h b/sql/sql_plugin.h
index 8ae38d58845..004d0d5abb7 100644
--- a/sql/sql_plugin.h
+++ b/sql/sql_plugin.h
@@ -79,6 +79,7 @@ struct st_plugin_int
   void *data;                   /* plugin type specific, e.g. handlerton */
   MEM_ROOT mem_root;            /* memory for dynamic plugin structures */
   sys_var *system_vars;         /* server variables for this plugin */
+  bool is_mandatory;            /* If true then plugin must not fail to load */
 };