percona-xtrabackup-2.4.21/sql/sql_plugin.cc

/*
   Copyright (c) 2005, 2019, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA */

#include "sql_plugin.h"

#include "mysql_version.h"
#include <mysql/plugin_auth.h>
#include <mysql/plugin_validate_password.h>
#include <mysql/plugin_group_replication.h>
#include <mysql/plugin_keyring.h>
#include "auth_common.h"       // check_table_access
#include "debug_sync.h"        // DEBUG_SYNC
#include "handler.h"           // ha_initalize_handlerton
#include "item.h"              // Item
#include "key.h"               // key_copy
#include "log.h"               // sql_print_error
#include "mutex_lock.h"        // Mutex_lock
#include "my_default.h"        // free_defaults
#include "records.h"           // READ_RECORD
#include "sql_audit.h"         // mysql_audit_acquire_plugins
#include "sql_base.h"          // close_mysql_tables
#include "sql_class.h"         // THD
#include "sql_parse.h"         // check_string_char_length
#include "sql_show.h"          // add_status_vars
#include "strfunc.h"           // find_type
#include "sys_vars_shared.h"   // intern_find_sys_var
#include "template_utils.h"    // pointer_cast
#include "transaction.h"       // trans_rollback_stmt

#ifndef EMBEDDED_LIBRARY
#include "srv_session.h"       // Srv_session::check_for_stale_threads()
#endif

#include <algorithm>

#ifdef HAVE_DLFCN_H
#include <dlfcn.h>
#endif

using std::min;
using std::max;

#define REPORT_TO_LOG  1
#define REPORT_TO_USER 2

#ifndef DBUG_OFF
static PSI_memory_key key_memory_plugin_ref;
#endif

static PSI_memory_key key_memory_plugin_mem_root;
static PSI_memory_key key_memory_plugin_init_tmp;
static PSI_memory_key key_memory_plugin_int_mem_root;
static PSI_memory_key key_memory_mysql_plugin;
static PSI_memory_key key_memory_mysql_plugin_dl;
static PSI_memory_key key_memory_plugin_bookmark;

extern st_mysql_plugin *mysql_optional_plugins[];
extern st_mysql_plugin *mysql_mandatory_plugins[];

/**
  @note The order of the enumeration is critical.
  @see construct_options
*/
const char *global_plugin_typelib_names[]=
  { "OFF", "ON", "FORCE", "FORCE_PLUS_PERMANENT", NULL };
static TYPELIB global_plugin_typelib=
  { array_elements(global_plugin_typelib_names)-1,
    "", global_plugin_typelib_names, NULL };

static I_List<i_string> opt_plugin_load_list;
I_List<i_string> *opt_plugin_load_list_ptr= &opt_plugin_load_list;
static I_List<i_string> opt_early_plugin_load_list;
I_List<i_string> *opt_early_plugin_load_list_ptr= &opt_early_plugin_load_list;
char *opt_plugin_dir_ptr;
char opt_plugin_dir[FN_REFLEN];
/*
  When you ad a new plugin type, add both a string and make sure that the
  init and deinit array are correctly updated.
*/
const LEX_STRING plugin_type_names[MYSQL_MAX_PLUGIN_TYPE_NUM]=
{
  { C_STRING_WITH_LEN("UDF") },
  { C_STRING_WITH_LEN("STORAGE ENGINE") },
  { C_STRING_WITH_LEN("FTPARSER") },
  { C_STRING_WITH_LEN("DAEMON") },
  { C_STRING_WITH_LEN("INFORMATION SCHEMA") },
  { C_STRING_WITH_LEN("AUDIT") },
  { C_STRING_WITH_LEN("REPLICATION") },
  { C_STRING_WITH_LEN("AUTHENTICATION") },
  { C_STRING_WITH_LEN("VALIDATE PASSWORD") },
  { C_STRING_WITH_LEN("GROUP REPLICATION") },
  { C_STRING_WITH_LEN("KEYRING") }
};

extern int initialize_schema_table(st_plugin_int *plugin);
extern int finalize_schema_table(st_plugin_int *plugin);

#ifdef EMBEDDED_LIBRARY
// Dummy implementations for embedded
int initialize_audit_plugin(st_plugin_int *plugin) { return 1; }
int finalize_audit_plugin(st_plugin_int *plugin) { return 0; }
#endif

/*
  The number of elements in both plugin_type_initialize and
  plugin_type_deinitialize should equal to the number of plugins
  defined.
*/
plugin_type_init plugin_type_initialize[MYSQL_MAX_PLUGIN_TYPE_NUM]=
{
  0,ha_initialize_handlerton,0,0,initialize_schema_table,
  initialize_audit_plugin,0,0,0
};

plugin_type_init plugin_type_deinitialize[MYSQL_MAX_PLUGIN_TYPE_NUM]=
{
  0,ha_finalize_handlerton,0,0,finalize_schema_table,
  finalize_audit_plugin,0,0,0
};

#ifdef HAVE_DLOPEN
static const char *plugin_interface_version_sym=
                   "_mysql_plugin_interface_version_";
static const char *sizeof_st_plugin_sym=
                   "_mysql_sizeof_struct_st_plugin_";
static const char *plugin_declarations_sym= "_mysql_plugin_declarations_";
static int min_plugin_interface_version= MYSQL_PLUGIN_INTERFACE_VERSION & ~0xFF;
#endif

static void*	innodb_callback_data;

/* Note that 'int version' must be the first field of every plugin
   sub-structure (plugin->info).
*/
static int min_plugin_info_interface_version[MYSQL_MAX_PLUGIN_TYPE_NUM]=
{
  0x0000,
  MYSQL_HANDLERTON_INTERFACE_VERSION,
  MYSQL_FTPARSER_INTERFACE_VERSION,
  MYSQL_DAEMON_INTERFACE_VERSION,
  MYSQL_INFORMATION_SCHEMA_INTERFACE_VERSION,
  MYSQL_AUDIT_INTERFACE_VERSION,
  MYSQL_REPLICATION_INTERFACE_VERSION,
  MYSQL_AUTHENTICATION_INTERFACE_VERSION,
  MYSQL_VALIDATE_PASSWORD_INTERFACE_VERSION,
  MYSQL_GROUP_REPLICATION_INTERFACE_VERSION,
  MYSQL_KEYRING_INTERFACE_VERSION
};
static int cur_plugin_info_interface_version[MYSQL_MAX_PLUGIN_TYPE_NUM]=
{
  0x0000, /* UDF: not implemented */
  MYSQL_HANDLERTON_INTERFACE_VERSION,
  MYSQL_FTPARSER_INTERFACE_VERSION,
  MYSQL_DAEMON_INTERFACE_VERSION,
  MYSQL_INFORMATION_SCHEMA_INTERFACE_VERSION,
  MYSQL_AUDIT_INTERFACE_VERSION,
  MYSQL_REPLICATION_INTERFACE_VERSION,
  MYSQL_AUTHENTICATION_INTERFACE_VERSION,
  MYSQL_VALIDATE_PASSWORD_INTERFACE_VERSION,
  MYSQL_GROUP_REPLICATION_INTERFACE_VERSION,
  MYSQL_KEYRING_INTERFACE_VERSION
};

/* support for Services */

#include "sql_plugin_services.h"

/*
  A mutex LOCK_plugin_delete must be acquired before calling plugin_del
  function.
*/
mysql_mutex_t LOCK_plugin_delete;

/**
  Serializes access to the global plugin memory list.

  LOCK_plugin must be acquired before accessing
  plugin_dl_array, plugin_array and plugin_hash.
  We are always manipulating ref count, so a rwlock here is unneccessary.
  If it must be taken together with the LOCK_system_variables_hash then
  LOCK_plugin must be taken before LOCK_system_variables_hash.
*/
mysql_mutex_t LOCK_plugin;
static Prealloced_array<st_plugin_dl*, 16> *plugin_dl_array;
static Prealloced_array<st_plugin_int*, 16> *plugin_array;
static HASH plugin_hash[MYSQL_MAX_PLUGIN_TYPE_NUM];
static bool reap_needed= false;
static int plugin_array_version=0;

static bool initialized= 0;

/*
  write-lock on LOCK_system_variables_hash is required before modifying
  the following variables/structures
*/
static MEM_ROOT plugin_mem_root;
static uint global_variables_dynamic_size= 0;
static HASH bookmark_hash;
/** Hash for system variables of string type with MEMALLOC flag. */
static HASH malloced_string_type_sysvars_bookmark_hash;


/*
  hidden part of opaque value passed to variable check functions.
  Used to provide a object-like structure to non C++ consumers.
*/
struct st_item_value_holder : public st_mysql_value
{
  Item *item;
};


/*
  stored in bookmark_hash, this structure is never removed from the
  hash and is used to mark a single offset for a thd local variable
  even if plugins have been uninstalled and reinstalled, repeatedly.
  This structure is allocated from plugin_mem_root.

  The key format is as follows:
    1 byte         - variable type code
    name_len bytes - variable name
    '\0'           - end of key
*/
struct st_bookmark
{
  size_t name_len;
  int offset;
  uint version;
  char key[1];
};


/*
  skeleton of a plugin variable - portion of structure common to all.
*/
struct st_mysql_sys_var
{
  MYSQL_PLUGIN_VAR_HEADER;
};

static SHOW_TYPE pluginvar_show_type(st_mysql_sys_var *plugin_var);


/*
  sys_var class for access to all plugin variables visible to the user
*/
class sys_var_pluginvar: public sys_var
{
  static bool on_check_pluginvar(sys_var *self, THD *thd, set_var *var);
public:
  st_plugin_int *plugin;
  st_mysql_sys_var *plugin_var;
  /**
    variable name from whatever is hard-coded in the plugin source
    and doesn't have pluginname- prefix is replaced by an allocated name
    with a plugin prefix. When plugin is uninstalled we need to restore the
    pointer to point to the hard-coded value, because plugin may be
    installed/uninstalled many times without reloading the shared object.
  */
  const char *orig_pluginvar_name;

  static void *operator new(size_t size, MEM_ROOT *mem_root)
  { return alloc_root(mem_root, size); }
  static void operator delete(void *ptr_arg,size_t size)
  { TRASH(ptr_arg, size); }

  sys_var_pluginvar(sys_var_chain *chain, const char *name_arg,
                    st_mysql_sys_var *plugin_var_arg)
    :sys_var(chain, name_arg, plugin_var_arg->comment,
             (plugin_var_arg->flags & PLUGIN_VAR_THDLOCAL ? SESSION : GLOBAL) |
             (plugin_var_arg->flags & PLUGIN_VAR_READONLY ? READONLY : 0) |
             (plugin_var_arg->flags & PLUGIN_VAR_INVISIBLE ? INVISIBLE : 0),
             0, -1, NO_ARG, pluginvar_show_type(plugin_var_arg), 0, 0,
             VARIABLE_NOT_IN_BINLOG,
             (plugin_var_arg->flags & PLUGIN_VAR_NODEFAULT) ?
               on_check_pluginvar : NULL,
             NULL, NULL, PARSE_NORMAL),
    plugin_var(plugin_var_arg), orig_pluginvar_name(plugin_var_arg->name)
  { plugin_var->name= name_arg; }
  sys_var_pluginvar *cast_pluginvar() { return this; }
  bool check_update_type(Item_result type);
  SHOW_TYPE show_type();
  uchar* real_value_ptr(THD *thd, enum_var_type type);
  TYPELIB* plugin_var_typelib(void);
  uchar* do_value_ptr(THD *running_thd, THD *target_thd, enum_var_type type, LEX_STRING *base);
  uchar* do_value_ptr(THD *thd, enum_var_type type, LEX_STRING *base)
  { return do_value_ptr(thd, thd, type, base); }
  uchar* session_value_ptr(THD *running_thd, THD *target_thd, LEX_STRING *base)
  { return do_value_ptr(running_thd, target_thd, OPT_SESSION, base); }
  uchar* global_value_ptr(THD *thd, LEX_STRING *base)
  { return do_value_ptr(thd, OPT_GLOBAL, base); }
  bool do_check(THD *thd, set_var *var);
  virtual void session_save_default(THD *thd, set_var *var) {}
  virtual void global_save_default(THD *thd, set_var *var) {}
  bool session_update(THD *thd, set_var *var);
  bool global_update(THD *thd, set_var *var);
};


/* prototypes */
static void plugin_load(MEM_ROOT *tmp_root, int *argc, char **argv);
static bool plugin_load_list(MEM_ROOT *tmp_root, int *argc, char **argv,
                             const char *list);
static my_bool check_if_option_is_deprecated(int optid,
                                             const struct my_option *opt,
                                             char *argument);
static int test_plugin_options(MEM_ROOT *, st_plugin_int *,
                               int *, char **);
static bool register_builtin(st_mysql_plugin *, st_plugin_int *,
                             st_plugin_int **);
static void unlock_variables(THD *thd, struct system_variables *vars);
static void cleanup_variables(THD *thd, struct system_variables *vars);
static void plugin_vars_free_values(sys_var *vars);
static bool plugin_var_memalloc_session_update(THD *thd,
                                               st_mysql_sys_var *var,
                                               char **dest, const char *value);
static bool plugin_var_memalloc_global_update(THD *thd,
                                              st_mysql_sys_var *var,
                                              char **dest, const char *value);
static void plugin_var_memalloc_free(struct system_variables *vars);
static void restore_pluginvar_names(sys_var *first);
static void plugin_opt_set_limits(struct my_option *,
                                  const st_mysql_sys_var *);
#define my_intern_plugin_lock(A,B) intern_plugin_lock(A,B)
#define my_intern_plugin_lock_ci(A,B) intern_plugin_lock(A,B)
static plugin_ref intern_plugin_lock(LEX *lex, plugin_ref plugin);
static void intern_plugin_unlock(LEX *lex, plugin_ref plugin);
static void reap_plugins(void);

static void report_error(int where_to, uint error, ...)
{
  va_list args;
  if (where_to & REPORT_TO_USER)
  {
    va_start(args, error);
    my_printv_error(error, ER(error), MYF(0), args);
    va_end(args);
  }
  if (where_to & REPORT_TO_LOG)
  {
    va_start(args, error);
    error_log_print(ERROR_LEVEL, ER_DEFAULT(error), args);
    va_end(args);
  }
}

/**
   Check if the provided path is valid in the sense that it does cause
   a relative reference outside the directory.

   @note Currently, this function only check if there are any
   characters in FN_DIRSEP in the string, but it might change in the
   future.

   @code
   check_valid_path("../foo.so") -> true
   check_valid_path("foo.so") -> false
   @endcode
 */
bool check_valid_path(const char *path, size_t len)
{
  size_t prefix= my_strcspn(files_charset_info, path, path + len, FN_DIRSEP,
                            strlen(FN_DIRSEP));
  return  prefix < len;
}


/****************************************************************************
  Value type thunks, allows the C world to play in the C++ world
****************************************************************************/

static int item_value_type(st_mysql_value *value)
{
  switch (((st_item_value_holder*)value)->item->result_type()) {
  case INT_RESULT:
    return MYSQL_VALUE_TYPE_INT;
  case REAL_RESULT:
    return MYSQL_VALUE_TYPE_REAL;
  default:
    return MYSQL_VALUE_TYPE_STRING;
  }
}

static const char *item_val_str(st_mysql_value *value,
                                char *buffer, int *length)
{
  String str(buffer, *length, system_charset_info), *res;
  if (!(res= ((st_item_value_holder*)value)->item->val_str(&str)))
    return NULL;
  *length= static_cast<int>(res->length());
  if (res->c_ptr_quick() == buffer)
    return buffer;

  /*
    Lets be nice and create a temporary string since the
    buffer was too small
  */
  return current_thd->strmake(res->c_ptr_quick(), res->length());
}


static int item_val_int(st_mysql_value *value, long long *buf)
{
  Item *item= ((st_item_value_holder*)value)->item;
  *buf= item->val_int();
  if (item->is_null())
    return 1;
  return 0;
}

static int item_is_unsigned(st_mysql_value *value)
{
  Item *item= ((st_item_value_holder*)value)->item;
  return item->unsigned_flag;
}

static int item_val_real(st_mysql_value *value, double *buf)
{
  Item *item= ((st_item_value_holder*)value)->item;
  *buf= item->val_real();
  if (item->is_null())
    return 1;
  return 0;
}


/****************************************************************************
  Plugin support code
****************************************************************************/

#ifdef HAVE_DLOPEN

static st_plugin_dl *plugin_dl_find(const LEX_STRING *dl)
{
  DBUG_ENTER("plugin_dl_find");
  for (st_plugin_dl **it= plugin_dl_array->begin();
       it != plugin_dl_array->end(); ++it)
  {
    st_plugin_dl *tmp= *it;
    if (tmp->ref_count &&
        ! my_strnncoll(files_charset_info,
                       pointer_cast<uchar*>(dl->str), dl->length,
                       pointer_cast<uchar*>(tmp->dl.str), tmp->dl.length))
      DBUG_RETURN(tmp);
  }
  DBUG_RETURN(NULL);
}


static st_plugin_dl *plugin_dl_insert_or_reuse(st_plugin_dl *plugin_dl)
{
  DBUG_ENTER("plugin_dl_insert_or_reuse");
  st_plugin_dl *tmp;
  for (st_plugin_dl **it= plugin_dl_array->begin();
       it != plugin_dl_array->end(); ++it)
  {
    tmp= *it;
    if (! tmp->ref_count)
    {
      memcpy(tmp, plugin_dl, sizeof(st_plugin_dl));
      DBUG_RETURN(tmp);
    }
  }
  if (plugin_dl_array->push_back(plugin_dl))
    DBUG_RETURN(NULL);
  tmp= plugin_dl_array->back()=
    static_cast<st_plugin_dl*>(memdup_root(&plugin_mem_root, plugin_dl,
                                           sizeof(st_plugin_dl)));
  DBUG_RETURN(tmp);
}
#endif /* HAVE_DLOPEN */


static inline void free_plugin_mem(st_plugin_dl *p)
{
#ifdef HAVE_DLOPEN
  if (p->handle)
    dlclose(p->handle);
#endif
  my_free(p->dl.str);
  if (p->version != MYSQL_PLUGIN_INTERFACE_VERSION)
    my_free(p->plugins);
}


/**
  Loads a dynamic plugin

  Fills in a ::st_plugin_dl structure.
  Initializes the plugin services pointer inside the plugin.
  Does not initialize the individual plugins.
  Must have LOCK_plugin locked. On error releases LOCK_plugin.

  @arg dl      The path to the plugin binary to load
  @arg report  a bitmask that's passed down to report_error()
*/
static st_plugin_dl *plugin_dl_add(const LEX_STRING *dl, int report)
{
#ifdef HAVE_DLOPEN
  char dlpath[FN_REFLEN];
  uint dummy_errors, i;
  size_t plugin_dir_len, dlpathlen;
  st_plugin_dl *tmp, plugin_dl;
  void *sym;
  DBUG_ENTER("plugin_dl_add");
  DBUG_PRINT("enter", ("dl->str: '%s', dl->length: %d",
                       dl->str, (int) dl->length));
  plugin_dir_len= strlen(opt_plugin_dir);
  /*
    Ensure that the dll doesn't have a path.
    This is done to ensure that only approved libraries from the
    plugin directory are used (to make this even remotely secure).
  */
  LEX_CSTRING dl_cstr= {dl->str, dl->length};
  if (check_valid_path(dl->str, dl->length) ||
      check_string_char_length(dl_cstr, "", NAME_CHAR_LEN,
                               system_charset_info, 1) ||
      plugin_dir_len + dl->length + 1 >= FN_REFLEN)
  {
    mysql_mutex_unlock(&LOCK_plugin);
    report_error(report, ER_UDF_NO_PATHS);
    DBUG_RETURN(NULL);
  }
  /* If this dll is already loaded just increase ref_count. */
  if ((tmp= plugin_dl_find(dl)))
  {
    tmp->ref_count++;
    DBUG_RETURN(tmp);
  }
  memset(&plugin_dl, 0, sizeof(plugin_dl));
  /* Compile dll path */
  dlpathlen=
    strxnmov(dlpath, sizeof(dlpath) - 1, opt_plugin_dir, "/", dl->str, NullS) -
    dlpath;
  (void) unpack_filename(dlpath, dlpath);
  plugin_dl.ref_count= 1;
  /* Open new dll handle */
  mysql_mutex_assert_owner(&LOCK_plugin);
  if (!(plugin_dl.handle= dlopen(dlpath, RTLD_NOW)))
  {
    const char *errmsg;
    int error_number= dlopen_errno;
    /*
      Conforming applications should use a critical section to retrieve
      the error pointer and buffer...
    */
    DLERROR_GENERATE(errmsg, error_number);

    if (!strncmp(dlpath, errmsg, dlpathlen))
    { // if errmsg starts from dlpath, trim this prefix.
      errmsg+=dlpathlen;
      if (*errmsg == ':') errmsg++;
      if (*errmsg == ' ') errmsg++;
    }
    mysql_mutex_unlock(&LOCK_plugin);
    report_error(report, ER_CANT_OPEN_LIBRARY, dlpath, error_number, errmsg);

    /*
      "The messages returned by dlerror() may reside in a static buffer
       that is overwritten on each call to dlerror()."

      Some implementations have a static pointer instead, and the memory it
      points to may be reported as "still reachable" by Valgrind.
      Calling dlerror() once more will free the memory.
     */
#if !defined(_WIN32)
    errmsg= dlerror();
    DBUG_ASSERT(errmsg == NULL);
#endif
    DBUG_RETURN(NULL);
  }
  /* Determine interface version */
  if (!(sym= dlsym(plugin_dl.handle, plugin_interface_version_sym)))
  {
    free_plugin_mem(&plugin_dl);
    mysql_mutex_unlock(&LOCK_plugin);
    report_error(report, ER_CANT_FIND_DL_ENTRY, plugin_interface_version_sym);
    DBUG_RETURN(NULL);
  }
  plugin_dl.version= *(int *)sym;
  /* Versioning */
  if (plugin_dl.version < min_plugin_interface_version ||
      (plugin_dl.version >> 8) > (MYSQL_PLUGIN_INTERFACE_VERSION >> 8))
  {
    free_plugin_mem(&plugin_dl);
    mysql_mutex_unlock(&LOCK_plugin);
    report_error(report, ER_CANT_OPEN_LIBRARY, dlpath, 0,
                 "plugin interface version mismatch");
    DBUG_RETURN(NULL);
  }

  /* link the services in */
  for (i= 0; i < array_elements(list_of_services); i++)
  {
    if ((sym= dlsym(plugin_dl.handle, list_of_services[i].name)))
    {
      uint ver= (uint)(intptr)*(void**)sym;
      if ((*(void**)sym) != list_of_services[i].service && /* already replaced */
          (ver > list_of_services[i].version ||
           (ver >> 8) < (list_of_services[i].version >> 8)))
      {
        char buf[MYSQL_ERRMSG_SIZE];
        my_snprintf(buf, sizeof(buf),
                    "service '%s' interface version mismatch",
                    list_of_services[i].name);
        mysql_mutex_unlock(&LOCK_plugin);
        report_error(report, ER_CANT_OPEN_LIBRARY, dlpath, 0, buf);
        DBUG_RETURN(NULL);
      }
      *(void**)sym= list_of_services[i].service;
    }
  }

  /* Find plugin declarations */
  if (!(sym= dlsym(plugin_dl.handle, plugin_declarations_sym)))
  {
    free_plugin_mem(&plugin_dl);
    mysql_mutex_unlock(&LOCK_plugin);
    report_error(report, ER_CANT_FIND_DL_ENTRY, plugin_declarations_sym);
    DBUG_RETURN(NULL);
  }

  if (plugin_dl.version != MYSQL_PLUGIN_INTERFACE_VERSION)
  {
    uint sizeof_st_plugin;
    st_mysql_plugin *old, *cur;
    char *ptr= (char *)sym;

    if ((sym= dlsym(plugin_dl.handle, sizeof_st_plugin_sym)))
      sizeof_st_plugin= *(int *)sym;
    else
    {
      /*
        When the following assert starts failing, we'll have to call
        report_error(report, ER_CANT_FIND_DL_ENTRY, sizeof_st_plugin_sym);
      */
      DBUG_ASSERT(min_plugin_interface_version == 0);
      sizeof_st_plugin= (int)offsetof(st_mysql_plugin, version);
    }

    /*
      What's the purpose of this loop? If the goal is to catch a
      missing 0 record at the end of a list, it will fail miserably
      since the compiler is likely to optimize this away. /Matz
     */
    for (i= 0;
         ((st_mysql_plugin *)(ptr+i*sizeof_st_plugin))->info;
         i++)
      /* no op */;

    cur= (st_mysql_plugin*)
      my_malloc(key_memory_mysql_plugin,
                (i+1)*sizeof(st_mysql_plugin), MYF(MY_ZEROFILL|MY_WME));
    if (!cur)
    {
      free_plugin_mem(&plugin_dl);
      mysql_mutex_unlock(&LOCK_plugin);
      report_error(report, ER_OUTOFMEMORY,
                   static_cast<int>(plugin_dl.dl.length));
      DBUG_RETURN(NULL);
    }
    /*
      All st_plugin fields not initialized in the plugin explicitly, are
      set to 0. It matches C standard behaviour for struct initializers that
      have less values than the struct definition.
    */
    for (i=0;
         (old=(st_mysql_plugin *)(ptr+i*sizeof_st_plugin))->info;
         i++)
      memcpy(cur+i, old, min<size_t>(sizeof(cur[i]), sizeof_st_plugin));

    sym= cur;
  }
  plugin_dl.plugins= (st_mysql_plugin *)sym;

  /*
    If report is REPORT_TO_USER, we were called from
    mysql_install_plugin. Otherwise, we are called directly or
    indirectly from plugin_init.
   */
  if (report == REPORT_TO_USER)
  {
    st_mysql_plugin *plugin= plugin_dl.plugins;
    for ( ; plugin->info ; ++plugin)
      if (plugin->flags & PLUGIN_OPT_NO_INSTALL)
      {
        mysql_mutex_unlock(&LOCK_plugin);
        report_error(report, ER_PLUGIN_NO_INSTALL, plugin->name);
        free_plugin_mem(&plugin_dl);
        DBUG_RETURN(NULL);
   }
  }

  /* Duplicate and convert dll name */
  plugin_dl.dl.length= dl->length * files_charset_info->mbmaxlen + 1;
  if (! (plugin_dl.dl.str= (char*) my_malloc(key_memory_mysql_plugin_dl,
                                             plugin_dl.dl.length, MYF(0))))
  {
    mysql_mutex_unlock(&LOCK_plugin);
    free_plugin_mem(&plugin_dl);
    report_error(report, ER_OUTOFMEMORY,
                 static_cast<int>(plugin_dl.dl.length));
    DBUG_RETURN(NULL);
  }
  plugin_dl.dl.length= copy_and_convert(plugin_dl.dl.str, plugin_dl.dl.length,
    files_charset_info, dl->str, dl->length, system_charset_info,
    &dummy_errors);
  plugin_dl.dl.str[plugin_dl.dl.length]= 0;
  /* Add this dll to array */
  if (! (tmp= plugin_dl_insert_or_reuse(&plugin_dl)))
  {
    mysql_mutex_unlock(&LOCK_plugin);
    free_plugin_mem(&plugin_dl);
    report_error(report, ER_OUTOFMEMORY,
                 static_cast<int>(sizeof(st_plugin_dl)));
    DBUG_RETURN(NULL);
  }
  DBUG_RETURN(tmp);
#else
  DBUG_ENTER("plugin_dl_add");
  report_error(report, ER_FEATURE_DISABLED, "plugin", "HAVE_DLOPEN");
  DBUG_RETURN(NULL);
#endif
}


static void plugin_dl_del(const LEX_STRING *dl)
{
#ifdef HAVE_DLOPEN
  DBUG_ENTER("plugin_dl_del");

  mysql_mutex_assert_owner(&LOCK_plugin);

  for (st_plugin_dl **it= plugin_dl_array->begin();
       it != plugin_dl_array->end(); ++it)
  {
    st_plugin_dl *tmp= *it;
    if (tmp->ref_count &&
        ! my_strnncoll(files_charset_info,
                       pointer_cast<uchar*>(dl->str), dl->length,
                       pointer_cast<uchar*>(tmp->dl.str), tmp->dl.length))
    {
      /* Do not remove this element, unless no other plugin uses this dll. */
      if (! --tmp->ref_count)
      {
        free_plugin_mem(tmp);
        memset(tmp, 0, sizeof(st_plugin_dl));
      }
      break;
    }
  }
  DBUG_VOID_RETURN;
#endif
}


static st_plugin_int *plugin_find_internal(const LEX_CSTRING &name,
                                                  int type)
{
  uint i;
  DBUG_ENTER("plugin_find_internal");
  if (!initialized || !name.str)
    DBUG_RETURN(NULL);

  mysql_mutex_assert_owner(&LOCK_plugin);

  if (type == MYSQL_ANY_PLUGIN)
  {
    for (i= 0; i < MYSQL_MAX_PLUGIN_TYPE_NUM; i++)
    {
      st_plugin_int *plugin= (st_plugin_int *)
        my_hash_search(&plugin_hash[i],
                       reinterpret_cast<const uchar*>(name.str), name.length);
      if (plugin)
        DBUG_RETURN(plugin);
    }
  }
  else
    DBUG_RETURN((st_plugin_int *)
        my_hash_search(&plugin_hash[type],
                       reinterpret_cast<const uchar*>(name.str),
                       name.length));
  DBUG_RETURN(NULL);
}


static SHOW_COMP_OPTION plugin_status(const LEX_CSTRING &name, int type)
{
  SHOW_COMP_OPTION rc= SHOW_OPTION_NO;
  st_plugin_int *plugin;
  DBUG_ENTER("plugin_is_ready");
  mysql_mutex_lock(&LOCK_plugin);
  if ((plugin= plugin_find_internal(name, type)))
  {
    rc= SHOW_OPTION_DISABLED;
    if (plugin->state == PLUGIN_IS_READY)
      rc= SHOW_OPTION_YES;
  }
  mysql_mutex_unlock(&LOCK_plugin);
  DBUG_RETURN(rc);
}


bool plugin_is_ready(const LEX_CSTRING &name, int type)
{
  bool rc= FALSE;
  if (plugin_status(name, type) == SHOW_OPTION_YES)
    rc= TRUE;
  return rc;
}


SHOW_COMP_OPTION plugin_status(const char *name, size_t len, int type)
{
  LEX_CSTRING plugin_name= { name, len };
  return plugin_status(plugin_name, type);
}


static plugin_ref intern_plugin_lock(LEX *lex, plugin_ref rc)
{
  st_plugin_int *pi= plugin_ref_to_int(rc);
  DBUG_ENTER("intern_plugin_lock");

  mysql_mutex_assert_owner(&LOCK_plugin);

  if (pi->state & (PLUGIN_IS_READY | PLUGIN_IS_UNINITIALIZED))
  {
    plugin_ref plugin;
#ifdef DBUG_OFF
    /* built-in plugins don't need ref counting */
    if (!pi->plugin_dl)
      DBUG_RETURN(pi);

    plugin= pi;
#else
    /*
      For debugging, we do an additional malloc which allows the
      memory manager and/or valgrind to track locked references and
      double unlocks to aid resolving reference counting problems.
    */
    if (!(plugin= (plugin_ref) my_malloc(key_memory_plugin_ref,
                                         sizeof(pi), MYF(MY_WME))))
      DBUG_RETURN(NULL);

    *plugin= pi;
#endif
    pi->ref_count++;
    DBUG_PRINT("info",("thd: %p, plugin: \"%s\", ref_count: %d",
                       current_thd, pi->name.str, pi->ref_count));
    if (lex)
      lex->plugins.push_back(plugin);
    DBUG_RETURN(plugin);
  }
  DBUG_RETURN(NULL);
}


plugin_ref plugin_lock(THD *thd, plugin_ref *ptr)
{
  LEX *lex= thd ? thd->lex : 0;
  plugin_ref rc;
  DBUG_ENTER("plugin_lock");
  mysql_mutex_lock(&LOCK_plugin);
  rc= my_intern_plugin_lock_ci(lex, *ptr);
  mysql_mutex_unlock(&LOCK_plugin);
  DBUG_RETURN(rc);
}


plugin_ref plugin_lock_by_name(THD *thd, const LEX_CSTRING &name, int type)
{
  LEX *lex= thd ? thd->lex : 0;
  plugin_ref rc= NULL;
  st_plugin_int *plugin;
  DBUG_ENTER("plugin_lock_by_name");
  mysql_mutex_lock(&LOCK_plugin);
  if ((plugin= plugin_find_internal(name, type)))
    rc= my_intern_plugin_lock_ci(lex, plugin_int_to_ref(plugin));
  mysql_mutex_unlock(&LOCK_plugin);
  DBUG_RETURN(rc);
}


static st_plugin_int *plugin_insert_or_reuse(st_plugin_int *plugin)
{
  DBUG_ENTER("plugin_insert_or_reuse");
  st_plugin_int *tmp;
  for (st_plugin_int **it= plugin_array->begin();
       it != plugin_array->end(); ++it)
  {
    tmp= *it;
    if (tmp->state == PLUGIN_IS_FREED)
    {
      memcpy(tmp, plugin, sizeof(st_plugin_int));
      DBUG_RETURN(tmp);
    }
  }
  if (plugin_array->push_back(plugin))
    DBUG_RETURN(NULL);
  tmp= plugin_array->back()=
    static_cast<st_plugin_int*>(memdup_root(&plugin_mem_root, plugin,
                                            sizeof(st_plugin_int)));
  DBUG_RETURN(tmp);
}


/**
  Adds a plugin to the global plugin list.

  Also installs the plugin variables.
  In case of error releases ::LOCK_plugin and reports the error
  @note Requires that a write-lock is held on ::LOCK_system_variables_hash
*/
static bool plugin_add(MEM_ROOT *tmp_root,
                       const LEX_STRING *name, const LEX_STRING *dl,
                       int *argc, char **argv, int report)
{
  st_plugin_int tmp;
  st_mysql_plugin *plugin;
  DBUG_ENTER("plugin_add");
  LEX_CSTRING name_cstr= {name->str, name->length};

  mysql_mutex_assert_owner(&LOCK_plugin);
  if (plugin_find_internal(name_cstr, MYSQL_ANY_PLUGIN))
  {
    mysql_mutex_unlock(&LOCK_plugin);
    report_error(report, ER_UDF_EXISTS, name->str);
    DBUG_RETURN(true);
  }
  /* Clear the whole struct to catch future extensions. */
  memset(&tmp, 0, sizeof(tmp));
  if (!(tmp.plugin_dl = plugin_dl_add(dl, report)))
  {
    DBUG_RETURN(true);
  }
  /* Find plugin by name */
  for (plugin= tmp.plugin_dl->plugins; plugin->info; plugin++)
  {
    size_t name_len= strlen(plugin->name);
    if (plugin->type >= 0 && plugin->type < MYSQL_MAX_PLUGIN_TYPE_NUM &&
        ! my_strnncoll(system_charset_info,
                       pointer_cast<const uchar*>(name->str), name->length,
                       pointer_cast<const uchar*>(plugin->name),
                       name_len))
    {
      st_plugin_int *tmp_plugin_ptr;
      if (*(int*)plugin->info <
          min_plugin_info_interface_version[plugin->type] ||
          ((*(int*)plugin->info) >> 8) >
          (cur_plugin_info_interface_version[plugin->type] >> 8))
      {
        char buf[256], dl_name[FN_REFLEN];
        strxnmov(buf, sizeof(buf) - 1, "API version for ",
                 plugin_type_names[plugin->type].str,
                 " plugin is too different", NullS);
        /* copy the library name so we can release the mutex */
        strncpy(dl_name, dl->str, sizeof(dl_name) - 1);
        dl_name[sizeof(dl_name) - 1] = 0;
        plugin_dl_del(dl);
        mysql_mutex_unlock(&LOCK_plugin);
        report_error(report, ER_CANT_OPEN_LIBRARY, dl_name, 0, buf);
        DBUG_RETURN(true);
      }
      tmp.plugin= plugin;
      tmp.name.str= (char *)plugin->name;
      tmp.name.length= name_len;
      tmp.ref_count= 0;
      tmp.state= PLUGIN_IS_UNINITIALIZED;
      tmp.load_option= PLUGIN_ON;
      if (test_plugin_options(tmp_root, &tmp, argc, argv))
        tmp.state= PLUGIN_IS_DISABLED;

      if ((tmp_plugin_ptr= plugin_insert_or_reuse(&tmp)))
      {
        plugin_array_version++;
        if (!my_hash_insert(&plugin_hash[plugin->type], (uchar*)tmp_plugin_ptr))
        {
          init_alloc_root(key_memory_plugin_int_mem_root,
                          &tmp_plugin_ptr->mem_root, 4096, 4096);
          DBUG_RETURN(false);
        }
        tmp_plugin_ptr->state= PLUGIN_IS_FREED;
      }
      mysql_del_sys_var_chain(tmp.system_vars);
      restore_pluginvar_names(tmp.system_vars);
      plugin_dl_del(dl);
      mysql_mutex_unlock(&LOCK_plugin);
      DBUG_RETURN(true);
    }
  }
  plugin_dl_del(dl);
  mysql_mutex_unlock(&LOCK_plugin);
  report_error(report, ER_CANT_FIND_DL_ENTRY, name->str);
  DBUG_RETURN(true);
}


static void plugin_deinitialize(st_plugin_int *plugin, bool ref_check)
{
  /*
    we don't want to hold the LOCK_plugin mutex as it may cause
    deinitialization to deadlock if plugins have worker threads
    with plugin locks
  */
  mysql_mutex_assert_not_owner(&LOCK_plugin);

  if (plugin->plugin->status_vars)
  {
    remove_status_vars(plugin->plugin->status_vars);
  }

  if (plugin_type_deinitialize[plugin->plugin->type])
  {
    if ((*plugin_type_deinitialize[plugin->plugin->type])(plugin))
    {
      sql_print_error("Plugin '%s' of type %s failed deinitialization",
                      plugin->name.str, plugin_type_names[plugin->plugin->type].str);
    }
  }
  else if (plugin->plugin->deinit)
  {
    DBUG_PRINT("info", ("Deinitializing plugin: '%s'", plugin->name.str));
    if (plugin->plugin->deinit(plugin))
    {
      DBUG_PRINT("warning", ("Plugin '%s' deinit function returned error.",
                             plugin->name.str));
    }
  }
  plugin->state= PLUGIN_IS_UNINITIALIZED;

#ifndef EMBEDDED_LIBRARY
  Srv_session::check_for_stale_threads(plugin);
#endif
  /*
    We do the check here because NDB has a worker THD which doesn't
    exit until NDB is shut down.
  */
  if (ref_check && plugin->ref_count)
    sql_print_error("Plugin '%s' has ref_count=%d after deinitialization.",
                    plugin->name.str, plugin->ref_count);
}

static void plugin_del(st_plugin_int *plugin)
{
  DBUG_ENTER("plugin_del(plugin)");
  mysql_mutex_assert_owner(&LOCK_plugin);
  mysql_mutex_assert_owner(&LOCK_plugin_delete);
  /* Free allocated strings before deleting the plugin. */
  mysql_rwlock_wrlock(&LOCK_system_variables_hash);
  mysql_del_sys_var_chain(plugin->system_vars);
  mysql_rwlock_unlock(&LOCK_system_variables_hash);
  restore_pluginvar_names(plugin->system_vars);
  plugin_vars_free_values(plugin->system_vars);
  my_hash_delete(&plugin_hash[plugin->plugin->type], (uchar*)plugin);

  if (plugin->plugin_dl)
    plugin_dl_del(&plugin->plugin_dl->dl);
  plugin->state= PLUGIN_IS_FREED;
  plugin_array_version++;
  free_root(&plugin->mem_root, MYF(0));
  DBUG_VOID_RETURN;
}

static void reap_plugins(void)
{
  st_plugin_int *plugin, **reap, **list;

  mysql_mutex_assert_owner(&LOCK_plugin);

  if (!reap_needed)
    return;

  reap_needed= false;
  const size_t count= plugin_array->size();
  reap= (st_plugin_int **)my_alloca(sizeof(plugin)*(count+1));
  *(reap++)= NULL;

  for (size_t idx= 0; idx < count; idx++)
  {
    plugin= plugin_array->at(idx);
    if (plugin->state == PLUGIN_IS_DELETED && !plugin->ref_count)
    {
      /* change the status flag to prevent reaping by another thread */
      plugin->state= PLUGIN_IS_DYING;
      *(reap++)= plugin;
    }
  }

  mysql_mutex_unlock(&LOCK_plugin);

  list= reap;
  while ((plugin= *(--list)))
  {
    if (!opt_bootstrap)
      sql_print_information("Shutting down plugin '%s'", plugin->name.str);
    plugin_deinitialize(plugin, true);
  }

  mysql_mutex_lock(&LOCK_plugin_delete);
  mysql_mutex_lock(&LOCK_plugin);

  while ((plugin= *(--reap)))
    plugin_del(plugin);

  mysql_mutex_unlock(&LOCK_plugin_delete);
}

static void intern_plugin_unlock(LEX *lex, plugin_ref plugin)
{
  st_plugin_int *pi;
  DBUG_ENTER("intern_plugin_unlock");

  mysql_mutex_assert_owner(&LOCK_plugin);

  if (!plugin)
    DBUG_VOID_RETURN;

  pi= plugin_ref_to_int(plugin);

#ifdef DBUG_OFF
  if (!pi->plugin_dl)
    DBUG_VOID_RETURN;
#else
  my_free(plugin);
#endif

  DBUG_PRINT("info",("unlocking plugin, name= %s, ref_count= %d",
                     pi->name.str, pi->ref_count));
  if (lex)
  {
    /*
      Remove one instance of this plugin from the use list.
      We are searching backwards so that plugins locked last
      could be unlocked faster - optimizing for LIFO semantics.
    */
    plugin_ref *iter= lex->plugins.end() - 1;
    bool found_it MY_ATTRIBUTE((unused)) = false;
    for (; iter >= lex->plugins.begin() - 1; --iter)
    {
      if (plugin == *iter)
      {
        lex->plugins.erase(iter);
        found_it= true;
        break;
      }
    }
    DBUG_ASSERT(found_it);
  }

  DBUG_ASSERT(pi->ref_count);
  pi->ref_count--;

  if (pi->state == PLUGIN_IS_DELETED && !pi->ref_count)
    reap_needed= true;

  DBUG_VOID_RETURN;
}


void plugin_unlock(THD *thd, plugin_ref plugin)
{
  LEX *lex= thd ? thd->lex : 0;
  DBUG_ENTER("plugin_unlock");
  if (!plugin)
    DBUG_VOID_RETURN;
#ifdef DBUG_OFF
  /* built-in plugins don't need ref counting */
  if (!plugin_dlib(plugin))
    DBUG_VOID_RETURN;
#endif
  mysql_mutex_lock(&LOCK_plugin);
  intern_plugin_unlock(lex, plugin);
  reap_plugins();
  mysql_mutex_unlock(&LOCK_plugin);
  DBUG_VOID_RETURN;
}


void plugin_unlock_list(THD *thd, plugin_ref *list, size_t count)
{
  LEX *lex= thd ? thd->lex : 0;
  DBUG_ENTER("plugin_unlock_list");
  DBUG_ASSERT(list);

  /*
    In unit tests, LOCK_plugin may be uninitialized, so do not lock it.
    Besides: there's no point in locking it, if there are no plugins to unlock.
   */
  if (count == 0)
    DBUG_VOID_RETURN;

  mysql_mutex_lock(&LOCK_plugin);
  while (count--)
    intern_plugin_unlock(lex, *list++);
  reap_plugins();
  mysql_mutex_unlock(&LOCK_plugin);
  DBUG_VOID_RETURN;
}

static int plugin_initialize(st_plugin_int *plugin)
{
  int ret= 1;
  DBUG_ENTER("plugin_initialize");

  mysql_mutex_assert_owner(&LOCK_plugin);
  uint state= plugin->state;
  DBUG_ASSERT(state == PLUGIN_IS_UNINITIALIZED);

  mysql_mutex_unlock(&LOCK_plugin);
  if (plugin_type_initialize[plugin->plugin->type])
  {
    if ((*plugin_type_initialize[plugin->plugin->type])(plugin))
    {
      sql_print_error("Plugin '%s' registration as a %s failed.",
                      plugin->name.str, plugin_type_names[plugin->plugin->type].str);
      goto err;
    }

    /* FIXME: Need better solution to transfer the callback function
    array to memcached */
    if (strcmp(plugin->name.str, "InnoDB") == 0) {
      innodb_callback_data = ((handlerton*)plugin->data)->data;
    }
  }
  else if (plugin->plugin->init)
  {
    if (strcmp(plugin->name.str, "daemon_memcached") == 0) {
       plugin->data = innodb_callback_data;
    }

    if (plugin->plugin->init(plugin))
    {
      sql_print_error("Plugin '%s' init function returned error.",
                      plugin->name.str);
      goto err;
    }
  }
  state= PLUGIN_IS_READY; // plugin->init() succeeded

  if (plugin->plugin->status_vars)
  {
    if (add_status_vars(plugin->plugin->status_vars))
      goto err;
  }

  /*
    set the plugin attribute of plugin's sys vars so they are pointing
    to the active plugin
  */
  if (plugin->system_vars)
  {
    sys_var_pluginvar *var= plugin->system_vars->cast_pluginvar();
    for (;;)
    {
      var->plugin= plugin;
      if (!var->next)
        break;
      var= var->next->cast_pluginvar();
    }
  }

  ret= 0;

err:
  mysql_mutex_lock(&LOCK_plugin);
  plugin->state= state;

  DBUG_RETURN(ret);
}


extern "C" uchar *get_plugin_hash_key(const uchar *, size_t *, my_bool);
extern "C" uchar *get_bookmark_hash_key(const uchar *, size_t *, my_bool);


uchar *get_plugin_hash_key(const uchar *buff, size_t *length,
                           my_bool not_used MY_ATTRIBUTE((unused)))
{
  st_plugin_int *plugin= (st_plugin_int *)buff;
  *length= (uint)plugin->name.length;
  return((uchar *)plugin->name.str);
}


uchar *get_bookmark_hash_key(const uchar *buff, size_t *length,
                             my_bool not_used MY_ATTRIBUTE((unused)))
{
  st_bookmark *var= (st_bookmark *)buff;
  *length= var->name_len + 1;
  return (uchar*) var->key;
}

static inline void convert_dash_to_underscore(char *str, size_t len)
{
  for (char *p= str; p <= str+len; p++)
    if (*p == '-')
      *p= '_';
}

static inline void convert_underscore_to_dash(char *str, size_t len)
{
  for (char *p= str; p <= str+len; p++)
    if (*p == '_')
      *p= '-';
}

#ifdef HAVE_PSI_INTERFACE
static PSI_mutex_key key_LOCK_plugin;
static PSI_mutex_key key_LOCK_plugin_delete;

static PSI_mutex_info all_plugin_mutexes[]=
{
  { &key_LOCK_plugin, "LOCK_plugin", PSI_FLAG_GLOBAL},
  { &key_LOCK_plugin_delete, "LOCK_plugin_delete", PSI_FLAG_GLOBAL}
};


static PSI_memory_info all_plugin_memory[]=
{
#ifndef DBUG_OFF
  { &key_memory_plugin_ref, "plugin_ref", PSI_FLAG_GLOBAL},
#endif
  { &key_memory_plugin_mem_root, "plugin_mem_root", PSI_FLAG_GLOBAL},
  { &key_memory_plugin_init_tmp, "plugin_init_tmp", 0},
  { &key_memory_plugin_int_mem_root, "plugin_int_mem_root", 0},
  { &key_memory_mysql_plugin_dl, "mysql_plugin_dl", 0},
  { &key_memory_mysql_plugin, "mysql_plugin", 0},
  { &key_memory_plugin_bookmark, "plugin_bookmark", PSI_FLAG_GLOBAL}
};

static void init_plugin_psi_keys(void)
{
  const char* category= "sql";
  int count;

  count= array_elements(all_plugin_mutexes);
  mysql_mutex_register(category, all_plugin_mutexes, count);

  count= array_elements(all_plugin_memory);
  mysql_memory_register(category, all_plugin_memory, count);
}
#endif /* HAVE_PSI_INTERFACE */


/*
  @brief
    Initialize the plugins. Reap those that fail to initialize.

  @return Operation outcome, false means no errors
*/
static bool plugin_init_initialize_and_reap()
{
  struct st_plugin_int *plugin_ptr;
  struct st_plugin_int **reap;

  /* Now we initialize all plugins that are not already initialized */
  mysql_mutex_lock(&LOCK_plugin);
  reap= (st_plugin_int **) my_alloca((plugin_array->size()+1) * sizeof(void*));
  *(reap++)= NULL;

  for (st_plugin_int **it= plugin_array->begin();
       it != plugin_array->end(); ++it)
  {
    plugin_ptr= *it;
    if (plugin_ptr->state == PLUGIN_IS_UNINITIALIZED)
    {
      if (plugin_initialize(plugin_ptr))
      {
        plugin_ptr->state= PLUGIN_IS_DYING;
        *(reap++)= plugin_ptr;
      }
    }
  }

  /* Check if any plugins have to be reaped */
  bool reaped_mandatory_plugin= false;
  while ((plugin_ptr= *(--reap)))
  {
    mysql_mutex_unlock(&LOCK_plugin);
    if (plugin_ptr->load_option == PLUGIN_FORCE ||
        plugin_ptr->load_option == PLUGIN_FORCE_PLUS_PERMANENT)
      reaped_mandatory_plugin= TRUE;
    plugin_deinitialize(plugin_ptr, true);
    mysql_mutex_lock(&LOCK_plugin_delete);
    mysql_mutex_lock(&LOCK_plugin);
    plugin_del(plugin_ptr);
    mysql_mutex_unlock(&LOCK_plugin_delete);
  }

  mysql_mutex_unlock(&LOCK_plugin);
  if (reaped_mandatory_plugin)
    return true;

  return false;
}

/**
  Initialize the internals of the plugin system. Allocate required
  resources, initialize mutex, etc.

  @return Operation outcome, false means no errors
 */
static bool plugin_init_internals()
{
#ifdef HAVE_PSI_INTERFACE
  init_plugin_psi_keys();
#endif

  init_alloc_root(key_memory_plugin_mem_root, &plugin_mem_root, 4096, 4096);

  if (my_hash_init(&bookmark_hash, &my_charset_bin, 16, 0, 0,
                   get_bookmark_hash_key, NULL, HASH_UNIQUE,
                   key_memory_plugin_bookmark))
      goto err;
  if (my_hash_init(&malloced_string_type_sysvars_bookmark_hash, &my_charset_bin,
                   16, 0, 0, get_bookmark_hash_key, NULL, HASH_UNIQUE,
                   key_memory_plugin_bookmark))
      goto err;

  mysql_mutex_init(key_LOCK_plugin, &LOCK_plugin, MY_MUTEX_INIT_FAST);
  mysql_mutex_init(key_LOCK_plugin_delete, &LOCK_plugin_delete, MY_MUTEX_INIT_FAST);

  plugin_dl_array= new (std::nothrow)
    Prealloced_array<st_plugin_dl*, 16>(key_memory_mysql_plugin_dl);
  plugin_array= new (std::nothrow)
    Prealloced_array<st_plugin_int*, 16>(key_memory_mysql_plugin);
  if (plugin_dl_array == NULL || plugin_array == NULL)
    goto err;

  for (uint i= 0; i < MYSQL_MAX_PLUGIN_TYPE_NUM; i++)
  {
    if (my_hash_init(&plugin_hash[i], system_charset_info, 16, 0, 0,
                     get_plugin_hash_key, NULL, HASH_UNIQUE,
                     key_memory_plugin_mem_root))
      goto err;
  }

  return false;

err:
  return true;
}

/**
   Register and initialize early plugins.

   @param argc  Command line argument counter
   @param argv  Command line arguments
   @param flags Flags to control whether dynamic loading
                and plugin initialization should be skipped

   @return Operation outcome, false if no errors
*/
bool plugin_register_early_plugins(int *argc, char **argv, int flags)
{
  bool retval= false;
  DBUG_ENTER("plugin_register_early_plugins");

  /* Don't allow initializing twice */
  DBUG_ASSERT(!initialized);

  /* Make sure the internals are initialized */
  if ((retval= plugin_init_internals()))
    DBUG_RETURN(retval);

  /* Allocate the temporary mem root, will be freed before returning */
  MEM_ROOT tmp_root;
  init_alloc_root(key_memory_plugin_init_tmp, &tmp_root, 4096, 4096);

  I_List_iterator<i_string> iter(opt_early_plugin_load_list);
  i_string *item;
  while (NULL != (item= iter++))
    plugin_load_list(&tmp_root, argc, argv, item->ptr);

  /* Temporary mem root not needed anymore, can free it here */
  free_root(&tmp_root, MYF(0));

  if (!(flags & PLUGIN_INIT_SKIP_INITIALIZATION))
    retval= plugin_init_initialize_and_reap();

  DBUG_RETURN(retval);
}

/**
  Register the builtin plugins. Some of the plugins (MyISAM, CSV and InnoDB)
  are also initialized.

  @param argc number of arguments, propagated to the plugin
  @param argv actual arguments, propagated to the plugin
  @return Operation outcome, false means no errors
 */
bool plugin_register_builtin_and_init_core_se(int *argc, char **argv)
{
  bool mandatory= true;
  DBUG_ENTER("plugin_register_builtin_and_init_core_se");

  /* Don't allow initializing twice */
  DBUG_ASSERT(!initialized);

  /* Allocate the temporary mem root, will be freed before returning */
  MEM_ROOT tmp_root;
  init_alloc_root(key_memory_plugin_init_tmp, &tmp_root, 4096, 4096);

  mysql_mutex_lock(&LOCK_plugin);
  initialized= true;

  /* First we register the builtin mandatory and optional plugins */
  for (struct st_mysql_plugin **builtins= mysql_mandatory_plugins;
       *builtins || mandatory; builtins++)
  {
    /* Switch to optional plugins when done with the mandatory ones */
    if (!*builtins)
    {
      builtins= mysql_optional_plugins;
      mandatory= false;
      if (!*builtins)
        break;
    }
    for (struct st_mysql_plugin *plugin= *builtins; plugin->info; plugin++)
    {
      struct st_plugin_int tmp;
      memset(&tmp, 0, sizeof(tmp));
      tmp.plugin= plugin;
      tmp.name.str= (char *)plugin->name;
      tmp.name.length= strlen(plugin->name);
      tmp.state= 0;
      tmp.load_option= mandatory ? PLUGIN_FORCE : PLUGIN_ON;

      /*
        If the performance schema is compiled in,
        treat the storage engine plugin as 'mandatory',
        to suppress any plugin-level options such as '--performance-schema'.
        This is specific to the performance schema, and is done on purpose:
        the server-level option '--performance-schema' controls the overall
        performance schema initialization, which consists of much more that
        the underlying storage engine initialization.
        See mysqld.cc, set_vars.cc.
        Suppressing ways to interfere directly with the storage engine alone
        prevents awkward situations where:
        - the user wants the performance schema functionality, by using
          '--enable-performance-schema' (the server option),
        - yet disable explicitly a component needed for the functionality
          to work, by using '--skip-performance-schema' (the plugin)
      */
      if (!my_strcasecmp(&my_charset_latin1, plugin->name, "PERFORMANCE_SCHEMA"))
      {
        tmp.load_option= PLUGIN_FORCE;
      }

      free_root(&tmp_root, MYF(MY_MARK_BLOCKS_FREE));
      if (test_plugin_options(&tmp_root, &tmp, argc, argv))
        tmp.state= PLUGIN_IS_DISABLED;
      else
        tmp.state= PLUGIN_IS_UNINITIALIZED;

      struct st_plugin_int *plugin_ptr;        // Pointer to registered plugin
      if (register_builtin(plugin, &tmp, &plugin_ptr))
        goto err_unlock;

      /*
        Only initialize MyISAM, InnoDB and CSV at this stage.
        Note that when the --help option is supplied, InnoDB is not
        initialized because the plugin table will not be read anyway,
        as indicated by the flag set when the plugin_init() function
        is called.
      */
      bool is_myisam= !my_strcasecmp(&my_charset_latin1, plugin->name, "MyISAM");
      bool is_innodb= !my_strcasecmp(&my_charset_latin1, plugin->name, "InnoDB");
      if (!is_myisam &&
          (!is_innodb || opt_help) &&
          my_strcasecmp(&my_charset_latin1, plugin->name, "CSV"))
        continue;

      if (plugin_ptr->state != PLUGIN_IS_UNINITIALIZED ||
          plugin_initialize(plugin_ptr))
        goto err_unlock;

      /*
        Initialize the global default storage engine so that it may
        not be null in any child thread.
      */
      if (is_myisam)
      {
        DBUG_ASSERT(!global_system_variables.table_plugin);
        DBUG_ASSERT(!global_system_variables.temp_table_plugin);
        global_system_variables.table_plugin=
          my_intern_plugin_lock(NULL, plugin_int_to_ref(plugin_ptr));
        global_system_variables.temp_table_plugin=
          my_intern_plugin_lock(NULL, plugin_int_to_ref(plugin_ptr));
        DBUG_ASSERT(plugin_ptr->ref_count == 2);
      }
    }
  }

#if 0
  /* Should now be set to MyISAM storage engine */
  DBUG_ASSERT(global_system_variables.table_plugin);
  DBUG_ASSERT(global_system_variables.temp_table_plugin);
#endif

  mysql_mutex_unlock(&LOCK_plugin);

  free_root(&tmp_root, MYF(0));
  DBUG_RETURN(false);

err_unlock:
  mysql_mutex_unlock(&LOCK_plugin);
  free_root(&tmp_root, MYF(0));
  DBUG_RETURN(true);
}

/**
  Register and initialize the dynamic plugins. Also initialize
  the remaining builtin plugins that are not initialized
  already.

  @param argc  Command line argument counter
  @param argv  Command line arguments
  @param flags Flags to control whether dynamic loading
               and plugin initialization should be skipped

  @return Operation outcome, false if no errors
*/
bool plugin_register_dynamic_and_init_all(int *argc,
                                          char **argv, int flags)
{
  DBUG_ENTER("plugin_register_dynamic_and_init_all");

  /* Make sure the internals are initialized and builtins registered */
  if (!initialized)
    DBUG_RETURN(true);

  /* Allocate the temporary mem root, will be freed before returning */
  MEM_ROOT tmp_root;
  init_alloc_root(key_memory_plugin_init_tmp, &tmp_root, 4096, 4096);

  /* Register all dynamic plugins */
  if (!(flags & PLUGIN_INIT_SKIP_DYNAMIC_LOADING))
  {
    I_List_iterator<i_string> iter(opt_plugin_load_list);
    i_string *item;
    while (NULL != (item= iter++))
      plugin_load_list(&tmp_root, argc, argv, item->ptr);

    if (!(flags & PLUGIN_INIT_SKIP_PLUGIN_TABLE))
      plugin_load(&tmp_root, argc, argv);
  }
  if (flags & PLUGIN_INIT_SKIP_INITIALIZATION)
    goto end;

  /*
    Now we initialize all remaining plugins
  */
  if(plugin_init_initialize_and_reap())
    goto err;

end:
  free_root(&tmp_root, MYF(0));

  DBUG_RETURN(0);

err:
  free_root(&tmp_root, MYF(0));
  DBUG_RETURN(1);
}

static bool register_builtin(st_mysql_plugin *plugin,
                             st_plugin_int *tmp,
                             st_plugin_int **ptr)
{
  DBUG_ENTER("register_builtin");
  tmp->ref_count= 0;
  tmp->plugin_dl= 0;

  if (plugin_array->push_back(tmp))
    DBUG_RETURN(true);

  *ptr= plugin_array->back()=
    static_cast<st_plugin_int*>(memdup_root(&plugin_mem_root, tmp,
                                            sizeof(st_plugin_int)));

  if (my_hash_insert(&plugin_hash[plugin->type],(uchar*) *ptr))
    DBUG_RETURN(1);

  DBUG_RETURN(0);
}


/**
  Reads the plugins from mysql.plugin and loads them

  Called only by plugin_init()
  a.k.a. the bootstrap sequence.

  @arg tmp_root  memory root to use for plugin_add()
  @arg argc      number of command line arguments to process
  @arg argv      array of command line argument to read values from
  @retval true   failure
  @retval false  success
*/
static void plugin_load(MEM_ROOT *tmp_root, int *argc, char **argv)
{
  THD thd;
  TABLE_LIST tables;
  TABLE *table;
  READ_RECORD read_record_info;
  int error;
  THD *new_thd= &thd;
  bool result;
#ifdef EMBEDDED_LIBRARY
  No_such_table_error_handler error_handler;
#endif /* EMBEDDED_LIBRARY */
  DBUG_ENTER("plugin_load");

  new_thd->thread_stack= (char*) &tables;
  new_thd->store_globals();
  LEX_CSTRING db_lex_cstr= { STRING_WITH_LEN("mysql") };
  new_thd->set_db(db_lex_cstr);
  thd.get_protocol_classic()->wipe_net();
  tables.init_one_table("mysql", 5, "plugin", 6, "plugin", TL_READ);

#ifdef EMBEDDED_LIBRARY
  /*
    When building an embedded library, if the mysql.plugin table
    does not exist, we silently ignore the missing table
  */
  new_thd->push_internal_handler(&error_handler);
#endif /* EMBEDDED_LIBRARY */

  result= open_trans_system_tables_for_read(new_thd, &tables);

#ifdef EMBEDDED_LIBRARY
  new_thd->pop_internal_handler();
  if (error_handler.safely_trapped_errors())
    DBUG_VOID_RETURN;
#endif /* EMBEDDED_LIBRARY */

  if (result)
  {
    DBUG_PRINT("error",("Can't open plugin table"));
    sql_print_error("Can't open the mysql.plugin table. Please "
                    "run mysql_upgrade to create it.");
    DBUG_VOID_RETURN;
  }
  table= tables.table;
  if (init_read_record(&read_record_info, new_thd, table, NULL, 1, 1, FALSE))
  {
    close_trans_system_tables(new_thd);
    DBUG_VOID_RETURN;
  }
  table->use_all_columns();
  /*
    there're no other threads running yet, so we don't need a mutex.
    but plugin_add() before is designed to work in multi-threaded
    environment, and it uses mysql_mutex_assert_owner(), so we lock
    the mutex here to satisfy the assert
  */
  while (!(error= read_record_info.read_record(&read_record_info)))
  {
    DBUG_PRINT("info", ("init plugin record"));
    String str_name, str_dl;
    get_field(tmp_root, table->field[0], &str_name);
    get_field(tmp_root, table->field[1], &str_dl);

    LEX_STRING name= {(char *)str_name.ptr(), str_name.length()};
    LEX_STRING dl= {(char *)str_dl.ptr(), str_dl.length()};

    /*
      The whole locking sequence is not strictly speaking needed since this
      is a function that's executed only during server bootstrap, but we do
      it properly for uniformity of the environment for plugin_add.
      Note that it must be done for each iteration since, unlike INSTALL PLUGIN
      the bootstrap process just reports the error and goes on.
      So to ensure the right sequence of lock and unlock we need to take and
      release both the wlock and the mutex.
    */
    mysql_mutex_lock(&LOCK_plugin);
    mysql_rwlock_wrlock(&LOCK_system_variables_hash);
    if (plugin_add(tmp_root, &name, &dl, argc, argv, REPORT_TO_LOG))
      sql_print_warning("Couldn't load plugin named '%s' with soname '%s'.",
                        str_name.c_ptr(), str_dl.c_ptr());
    else
      mysql_mutex_unlock(&LOCK_plugin);
    mysql_rwlock_unlock(&LOCK_system_variables_hash);
    free_root(tmp_root, MYF(MY_MARK_BLOCKS_FREE));
  }
  if (error > 0)
    sql_print_error(ER(ER_GET_ERRNO), my_errno);
  end_read_record(&read_record_info);
  table->m_needs_reopen= TRUE;                  // Force close to free memory

  close_trans_system_tables(new_thd);

  DBUG_VOID_RETURN;
}


/**
  Load a list of plugins

  Called by plugin_register_early_plugins() and
  plugin_register_dynamic_and_init_all(), a.k.a. the bootstrap sequence.

  @arg tmp_root  memory root to use for plugin_add()
  @arg argc      number of command line arguments to process
  @arg argv      array of command line argument to read values from
  @arg list      list of plugins to load. Ends with a NULL pointer
  @retval true   failure
  @retval false  success
*/
static bool plugin_load_list(MEM_ROOT *tmp_root, int *argc, char **argv,
                             const char *list)
{
  char buffer[FN_REFLEN];
  LEX_STRING name= {buffer, 0}, dl= {NULL, 0}, *str= &name;
  st_plugin_dl *plugin_dl;
  st_mysql_plugin *plugin;
  char *p= buffer;
  DBUG_ENTER("plugin_load_list");
  while (list)
  {
    if (p == buffer + sizeof(buffer) - 1)
    {
      sql_print_error("plugin-load parameter too long");
      DBUG_RETURN(TRUE);
    }

    switch ((*(p++)= *(list++))) {
    case '\0':
      list= NULL; /* terminate the loop */
      /* fall through */
    case ';':
#ifndef _WIN32
    case ':':     /* can't use this as delimiter as it may be drive letter */
#endif
      str->str[str->length]= '\0';
      if (str == &name)  // load all plugins in named module
      {
        if (!name.length)
        {
          p--;    /* reset pointer */
          continue;
        }

        dl= name;
        /*
          The whole locking sequence is not strictly speaking needed since this
          is a function that's executed only during server bootstrap, but we do
          it properly for uniformity of the environment for plugin_add.
        */
        mysql_mutex_lock(&LOCK_plugin);
        mysql_rwlock_wrlock(&LOCK_system_variables_hash);
        if ((plugin_dl= plugin_dl_add(&dl, REPORT_TO_LOG)))
        {
          for (plugin= plugin_dl->plugins; plugin->info; plugin++)
          {
            name.str= (char *) plugin->name;
            name.length= strlen(name.str);

            free_root(tmp_root, MYF(MY_MARK_BLOCKS_FREE));
            if (plugin_add(tmp_root, &name, &dl, argc, argv, REPORT_TO_LOG))
            {
              mysql_rwlock_unlock(&LOCK_system_variables_hash);
              goto error;
            }
          }
          plugin_dl_del(&dl); // reduce ref count
        }
        else
        {
          mysql_rwlock_unlock(&LOCK_system_variables_hash);
          goto error;
        }
      }
      else
      {
        free_root(tmp_root, MYF(MY_MARK_BLOCKS_FREE));
        /*
          The whole locking sequence is not strictly speaking needed since this
          is a function that's executed only during server bootstrap, but we do
          it properly for uniformity of the environment for plugin_add.
        */
        mysql_mutex_lock(&LOCK_plugin);
        mysql_rwlock_wrlock(&LOCK_system_variables_hash);
        if (plugin_add(tmp_root, &name, &dl, argc, argv, REPORT_TO_LOG))
        {
          mysql_rwlock_unlock(&LOCK_system_variables_hash);
          goto error;
        }
      }
      mysql_mutex_unlock(&LOCK_plugin);
      mysql_rwlock_unlock(&LOCK_system_variables_hash);
      name.length= dl.length= 0;
      dl.str= NULL; name.str= p= buffer;
      str= &name;
      continue;
    case '=':
    case '#':
      if (str == &name)
      {
        name.str[name.length]= '\0';
        str= &dl;
        str->str= p;
        continue;
      }
      // Fall through.
    default:
      str->length++;
      continue;
    }
  }
  DBUG_RETURN(FALSE);
error:
  sql_print_error("Couldn't load plugin named '%s' with soname '%s'.",
                  name.str, dl.str);
  DBUG_RETURN(TRUE);
}

/*
  Shutdown memcached plugin before binlog shuts down
*/
void memcached_shutdown(void)
{
  if (initialized)
  {

    for (st_plugin_int **it= plugin_array->begin();
         it != plugin_array->end(); ++it)
    {
      st_plugin_int *plugin= *it;

      if (plugin->state == PLUGIN_IS_READY
	  && strcmp(plugin->name.str, "daemon_memcached") == 0)
      {
	plugin_deinitialize(plugin, true);

        mysql_mutex_lock(&LOCK_plugin);
	plugin->state= PLUGIN_IS_DYING;
	plugin_del(plugin);
        mysql_mutex_unlock(&LOCK_plugin);
      }
    }

  }
}

void plugin_shutdown(void)
{
  size_t i;
  st_plugin_int **plugins, *plugin;
  st_plugin_dl **dl;
  bool skip_binlog = true;

  DBUG_ENTER("plugin_shutdown");

  if (initialized)
  {
    size_t count= plugin_array->size();
    mysql_mutex_lock(&LOCK_plugin);

    reap_needed= true;

    /*
      We want to shut down plugins in a reasonable order, this will
      become important when we have plugins which depend upon each other.
      Circular references cannot be reaped so they are forced afterwards.
      TODO: Have an additional step here to notify all active plugins that
      shutdown is requested to allow plugins to deinitialize in parallel.
    */
    while (reap_needed && (count= plugin_array->size()))
    {
      reap_plugins();
      for (i= 0; i < count; i++)
      {
        plugin= plugin_array->at(i);

	if (plugin->state == PLUGIN_IS_READY
	    && strcmp(plugin->name.str, "binlog") == 0 && skip_binlog)
	{
		skip_binlog = false;

	} else if (plugin->state == PLUGIN_IS_READY)
        {
          plugin->state= PLUGIN_IS_DELETED;
          reap_needed= true;
        }
      }
      if (!reap_needed)
      {
        /*
          release any plugin references held.
        */
        unlock_variables(NULL, &global_system_variables);
        unlock_variables(NULL, &max_system_variables);
      }
    }

    plugins= (st_plugin_int **) my_alloca(sizeof(void*) * (count+1));

    /*
      If we have any plugins which did not die cleanly, we force shutdown
    */
    for (i= 0; i < count; i++)
    {
      plugins[i]= plugin_array->at(i);
      /* change the state to ensure no reaping races */
      if (plugins[i]->state == PLUGIN_IS_DELETED)
        plugins[i]->state= PLUGIN_IS_DYING;
    }
    mysql_mutex_unlock(&LOCK_plugin);

    /*
      We loop through all plugins and call deinit() if they have one.
    */
    for (i= 0; i < count; i++)
      if (!(plugins[i]->state & (PLUGIN_IS_UNINITIALIZED | PLUGIN_IS_FREED |
                                 PLUGIN_IS_DISABLED)))
      {
        sql_print_warning("Plugin '%s' will be forced to shutdown",
                          plugins[i]->name.str);
        /*
          We are forcing deinit on plugins so we don't want to do a ref_count
          check until we have processed all the plugins.
        */
        plugin_deinitialize(plugins[i], false);
      }

    /*
      It's perfectly safe not to lock LOCK_plugin, LOCK_plugin_delete, as
      there're no concurrent threads anymore. But some functions called from
      here use mysql_mutex_assert_owner(), so we lock the mutex to satisfy it
    */
    mysql_mutex_lock(&LOCK_plugin_delete);
    mysql_mutex_lock(&LOCK_plugin);

    /*
      We defer checking ref_counts until after all plugins are deinitialized
      as some may have worker threads holding on to plugin references.
    */
    for (i= 0; i < count; i++)
    {
      if (plugins[i]->ref_count)
        sql_print_error("Plugin '%s' has ref_count=%d after shutdown.",
                        plugins[i]->name.str, plugins[i]->ref_count);
      if (plugins[i]->state & PLUGIN_IS_UNINITIALIZED)
        plugin_del(plugins[i]);
    }

    /*
      Now we can deallocate all memory.
    */

    cleanup_variables(NULL, &global_system_variables);
    cleanup_variables(NULL, &max_system_variables);
    mysql_mutex_unlock(&LOCK_plugin);
    mysql_mutex_unlock(&LOCK_plugin_delete);

    initialized= 0;
    mysql_mutex_destroy(&LOCK_plugin);
    mysql_mutex_destroy(&LOCK_plugin_delete);
  }

  /* Dispose of the memory */

  for (i= 0; i < MYSQL_MAX_PLUGIN_TYPE_NUM; i++)
    my_hash_free(&plugin_hash[i]);
  delete plugin_array;
  plugin_array= NULL;

  if (plugin_dl_array != NULL)
  {
    size_t count= plugin_dl_array->size();
    dl= (st_plugin_dl **)my_alloca(sizeof(void*) * count);
    for (i= 0; i < count; i++)
      dl[i]= plugin_dl_array->at(i);
    for (i= 0; i < plugin_dl_array->size(); i++)
      free_plugin_mem(dl[i]);
    delete plugin_dl_array;
    plugin_dl_array= NULL;
  }

  my_hash_free(&bookmark_hash);
  my_hash_free(&malloced_string_type_sysvars_bookmark_hash);
  free_root(&plugin_mem_root, MYF(0));

  global_variables_dynamic_size= 0;

  DBUG_VOID_RETURN;
}

/**
  Initialize one plugin. This function is used to early load one single
  plugin. This function is used by key migration tool.

   @param[in]   argc  Command line argument counter
   @param[in]   argv  Command line arguments
   @param[in]   plugin library file name

   @return Operation status
     @retval 0 OK
     @retval 1 ERROR
*/
bool plugin_early_load_one(int *argc, char **argv, const char* plugin)
{
  bool retval= false;
  DBUG_ENTER("plugin_early_load_one");

  /* Make sure the internals are initialized */
  if (!initialized)
  {
    if ((retval= plugin_init_internals()))
      DBUG_RETURN(retval);
    else
      initialized= true;
  }
  /* Allocate the temporary mem root, will be freed before returning */
  MEM_ROOT tmp_root;
  init_alloc_root(PSI_NOT_INSTRUMENTED, &tmp_root, 4096, 4096);

  plugin_load_list(&tmp_root, argc, argv, plugin);

  /* Temporary mem root not needed anymore, can free it here */
  free_root(&tmp_root, MYF(0));

  retval= plugin_init_initialize_and_reap();

  DBUG_RETURN(retval);
}

static bool mysql_install_plugin(THD *thd, const LEX_STRING *name,
                                 const LEX_STRING *dl)
{
  TABLE_LIST tables;
  TABLE *table;
  bool error= true;
  int argc= orig_argc;
  char **argv= orig_argv;
  st_plugin_int *tmp;
  LEX_CSTRING name_cstr= {name->str, name->length};

  DBUG_ENTER("mysql_install_plugin");

  tables.init_one_table("mysql", 5, "plugin", 6, "plugin", TL_WRITE);

  if (!opt_noacl &&
      check_table_access(thd, INSERT_ACL, &tables, false, 1, false))
    DBUG_RETURN(true);

  /* need to open before acquiring LOCK_plugin or it will deadlock */
  if (! (table = open_ltable(thd, &tables, TL_WRITE,
                             MYSQL_LOCK_IGNORE_TIMEOUT)))
    DBUG_RETURN(true);

  /*
    Pre-acquire audit plugins for events that may potentially occur
    during [UN]INSTALL PLUGIN.

    When audit event is triggered, audit subsystem acquires interested
    plugins by walking through plugin list. Evidently plugin list
    iterator protects plugin list by acquiring LOCK_plugin, see
    plugin_foreach_with_mask().

    On the other hand [UN]INSTALL PLUGIN is acquiring LOCK_plugin
    rather for a long time.

    When audit event is triggered during [UN]INSTALL PLUGIN, plugin
    list iterator acquires the same lock (within the same thread)
    second time.

    This hack should be removed when LOCK_plugin is fixed so it
    protects only what it supposed to protect.
    */
#ifndef EMBEDDED_LIBRARY
  mysql_audit_acquire_plugins(thd, MYSQL_AUDIT_GENERAL_CLASS,
                              MYSQL_AUDIT_GENERAL_ALL);
#endif

  mysql_mutex_lock(&LOCK_plugin);
  DEBUG_SYNC(thd, "acquired_LOCK_plugin");
  mysql_rwlock_wrlock(&LOCK_system_variables_hash);

  if (my_load_defaults(MYSQL_CONFIG_NAME, load_default_groups,
                       &argc, &argv, NULL))
  {
    mysql_mutex_unlock(&LOCK_plugin);
    mysql_rwlock_unlock(&LOCK_system_variables_hash);
    report_error(REPORT_TO_USER, ER_PLUGIN_IS_NOT_LOADED, name->str);
    goto err;
  }
  error= plugin_add(thd->mem_root, name, dl, &argc, argv, REPORT_TO_USER);
  if (argv)
    free_defaults(argv);
  mysql_rwlock_unlock(&LOCK_system_variables_hash);

  /* LOCK_plugin already unlocked by plugin_add() if error */
  if (error)
    goto err;

  if (!(tmp = plugin_find_internal(name_cstr, MYSQL_ANY_PLUGIN)))
  {
    mysql_mutex_unlock(&LOCK_plugin);
    goto err;
  }

  if (tmp->state == PLUGIN_IS_DISABLED)
  {
    push_warning_printf(thd, Sql_condition::SL_WARNING,
                        ER_CANT_INITIALIZE_UDF, ER(ER_CANT_INITIALIZE_UDF),
                        name->str, "Plugin is disabled");
  }
  else
  {
    if (plugin_initialize(tmp))
    {
      mysql_mutex_unlock(&LOCK_plugin);
      my_error(ER_CANT_INITIALIZE_UDF, MYF(0), name->str,
               "Plugin initialization function failed.");
      goto deinit;
    }
  }
  mysql_mutex_unlock(&LOCK_plugin);

  /*
    We do not replicate the INSTALL PLUGIN statement. Disable binlogging
    of the insert into the plugin table, so that it is not replicated in
    row based mode.
  */
  tmp_disable_binlog(thd);
  table->use_all_columns();
  restore_record(table, s->default_values);
  table->field[0]->store(name->str, name->length, system_charset_info);
  table->field[1]->store(dl->str, dl->length, files_charset_info);
  error= table->file->ha_write_row(table->record[0]);
  reenable_binlog(thd);
  if (error)
  {
    table->file->print_error(error, MYF(0));
    trans_rollback_stmt(thd);
    goto deinit;
  }
  else
    trans_commit_stmt(thd);

  close_mysql_tables(thd);
  DBUG_RETURN(false);
deinit:
  mysql_mutex_lock(&LOCK_plugin);
  tmp->state= PLUGIN_IS_DELETED;
  reap_needed= true;
  reap_plugins();
  mysql_mutex_unlock(&LOCK_plugin);
err:
  trans_rollback_stmt(thd);
  close_mysql_tables(thd);

  DBUG_RETURN(true);
}


static bool mysql_uninstall_plugin(THD *thd, const LEX_STRING *name)
{
  TABLE *table;
  TABLE_LIST tables;
  st_plugin_int *plugin;
  LEX_CSTRING name_cstr={name->str, name->length};
  bool error= true;

  DBUG_ENTER("mysql_uninstall_plugin");

  tables.init_one_table("mysql", 5, "plugin", 6, "plugin", TL_WRITE);

  if (!opt_noacl &&
      check_table_access(thd, DELETE_ACL, &tables, false, 1, false))
    DBUG_RETURN(true);

  /* need to open before acquiring LOCK_plugin or it will deadlock */
  if (! (table= open_ltable(thd, &tables, TL_WRITE, MYSQL_LOCK_IGNORE_TIMEOUT)))
    DBUG_RETURN(true);

  if (!table->key_info)
  {
    my_error(ER_MISSING_KEY, MYF(0), table->s->db.str,
             table->s->table_name.str);
    trans_rollback_stmt(thd);
    close_thread_tables(thd);
    DBUG_RETURN(true);
  }

  /*
    Pre-acquire audit plugins for events that may potentially occur
    during [UN]INSTALL PLUGIN.

    When audit event is triggered, audit subsystem acquires interested
    plugins by walking through plugin list. Evidently plugin list
    iterator protects plugin list by acquiring LOCK_plugin, see
    plugin_foreach_with_mask().

    On the other hand [UN]INSTALL PLUGIN is acquiring LOCK_plugin
    rather for a long time.

    When audit event is triggered during [UN]INSTALL PLUGIN, plugin
    list iterator acquires the same lock (within the same thread)
    second time.

    This hack should be removed when LOCK_plugin is fixed so it
    protects only what it supposed to protect.
  */
#ifndef EMBEDDED_LIBRARY
  mysql_audit_acquire_plugins(thd, MYSQL_AUDIT_GENERAL_CLASS,
                                   MYSQL_AUDIT_GENERAL_ALL);
#endif

  mysql_mutex_lock(&LOCK_plugin);
  if (!(plugin= plugin_find_internal(name_cstr, MYSQL_ANY_PLUGIN)) ||
      plugin->state & (PLUGIN_IS_UNINITIALIZED | PLUGIN_IS_DYING))
  {
    mysql_mutex_unlock(&LOCK_plugin);
    my_error(ER_SP_DOES_NOT_EXIST, MYF(0), "PLUGIN", name->str);
    goto err;
  }
  if (!plugin->plugin_dl)
  {
    mysql_mutex_unlock(&LOCK_plugin);
    my_error(ER_PLUGIN_DELETE_BUILTIN, MYF(0));
    goto err;
  }
  if (plugin->load_option == PLUGIN_FORCE_PLUS_PERMANENT)
  {
    mysql_mutex_unlock(&LOCK_plugin);
    my_error(ER_PLUGIN_IS_PERMANENT, MYF(0), name->str);
    goto err;
  }
  /*
    Error message for ER_PLUGIN_IS_PERMANENT is not suitable for
    plugins marked as not dynamically uninstallable, so we have a
    separate one instead of changing the old one.
   */
  if (plugin->plugin->flags & PLUGIN_OPT_NO_UNINSTALL)
  {
    mysql_mutex_unlock(&LOCK_plugin);
    my_error(ER_PLUGIN_NO_UNINSTALL, MYF(0), plugin->plugin->name);
    goto err;
  }

#ifdef HAVE_REPLICATION
  /* Block Uninstallation of semi_sync plugins (Master/Slave)
     when they are busy
   */
  char buff[20];
  size_t buff_length;
  /*
    Master: If there are active semi sync slaves for this Master,
    then that means it is busy and rpl_semi_sync_master plugin
    cannot be uninstalled. To check whether the master
    has any semi sync slaves or not, check Rpl_semi_sync_master_cliens
    status variable value, if it is not 0, that means it is busy.
  */
  if (!strcmp(name->str, "rpl_semi_sync_master") &&
      get_status_var(thd,
                     plugin->plugin->status_vars,
                     "Rpl_semi_sync_master_clients",
                     buff, OPT_DEFAULT, &buff_length) &&
      strcmp(buff,"0") )
  {
    mysql_mutex_unlock(&LOCK_plugin);
    my_error(ER_PLUGIN_CANNOT_BE_UNINSTALLED, MYF(0), name->str,
             "Stop any active semisynchronous slaves of this master first.");
    goto err;
  }
  /* Slave: If there is semi sync enabled IO thread active on this Slave,
    then that means plugin is busy and rpl_semi_sync_slave plugin
    cannot be uninstalled. To check whether semi sync
    IO thread is active or not, check Rpl_semi_sync_slave_status status
    variable value, if it is ON, that means it is busy.
  */
  if (!strcmp(name->str, "rpl_semi_sync_slave") &&
      get_status_var(thd, plugin->plugin->status_vars,
                     "Rpl_semi_sync_slave_status",
                     buff, OPT_DEFAULT, &buff_length) &&
      !strcmp(buff,"ON") )
  {
    mysql_mutex_unlock(&LOCK_plugin);
    my_error(ER_PLUGIN_CANNOT_BE_UNINSTALLED, MYF(0), name->str,
             "Stop any active semisynchronous I/O threads on this slave first.");
    goto err;
  }

  /* If Group Replication is in use, the plugin can't be uninstalled.
   * The command STOP GROUP_REPLICATION should be used before uninstall.
  */
  if (plugin->ref_count && !strcmp(name->str, "group_replication"))
  {
    mysql_mutex_unlock(&LOCK_plugin);
    my_error(ER_PLUGIN_CANNOT_BE_UNINSTALLED, MYF(0), name->str,
             "Plugin is busy, it cannot be uninstalled. To force a"
             " stop run STOP GROUP_REPLICATION and then UNINSTALL"
             " PLUGIN group_replication.");
    goto err;
  }
#endif

  plugin->state= PLUGIN_IS_DELETED;
  if (plugin->ref_count)
    push_warning(thd, Sql_condition::SL_WARNING,
                 WARN_PLUGIN_BUSY, ER(WARN_PLUGIN_BUSY));
  else
    reap_needed= true;
  reap_plugins();
  mysql_mutex_unlock(&LOCK_plugin);

  uchar user_key[MAX_KEY_LENGTH];
  table->use_all_columns();
  table->field[0]->store(name->str, name->length, system_charset_info);
  key_copy(user_key, table->record[0], table->key_info,
           table->key_info->key_length);

  if (! table->file->ha_index_read_idx_map(table->record[0], 0, user_key,
                                           HA_WHOLE_KEY, HA_READ_KEY_EXACT))
  {
    /*
      We do not replicate the UNINSTALL PLUGIN statement. Disable binlogging
      of the delete from the plugin table, so that it is not replicated in
      row based mode.
    */
    tmp_disable_binlog(thd);
    error= table->file->ha_delete_row(table->record[0]);
    reenable_binlog(thd);
    if (error)
      table->file->print_error(error, MYF(0));
  }
  else
  {
    error= false;
  }

  if (error)
    trans_rollback_stmt(thd);
  else
    trans_commit_stmt(thd);

  close_mysql_tables(thd);

  DBUG_RETURN(error);
err:
  trans_rollback_stmt(thd);
  close_mysql_tables(thd);

  DBUG_RETURN(true);
}

bool plugin_foreach_with_mask(THD *thd, plugin_foreach_func **funcs,
                              int type, uint state_mask, void *arg)
{
  size_t idx, total;
  st_plugin_int *plugin, **plugins;
  int version=plugin_array_version;
  DBUG_ENTER("plugin_foreach_with_mask");

  if (!initialized)
    DBUG_RETURN(FALSE);

  state_mask= ~state_mask; // do it only once

  mysql_mutex_lock(&LOCK_plugin);
  total= type == MYSQL_ANY_PLUGIN ? plugin_array->size()
                                  : plugin_hash[type].records;
  /*
    Do the alloca out here in case we do have a working alloca:
        leaving the nested stack frame invalidates alloca allocation.
  */
  plugins=(st_plugin_int **)my_alloca(total*sizeof(plugin));
  if (type == MYSQL_ANY_PLUGIN)
  {
    for (idx= 0; idx < total; idx++)
    {
      plugin= plugin_array->at(idx);
      plugins[idx]= !(plugin->state & state_mask) ? plugin : NULL;
    }
  }
  else
  {
    HASH *hash= plugin_hash + type;
    for (idx= 0; idx < total; idx++)
    {
      plugin= (st_plugin_int *) my_hash_element(hash, idx);
      plugins[idx]= !(plugin->state & state_mask) ? plugin : NULL;
    }
  }
  mysql_mutex_unlock(&LOCK_plugin);

  for (;*funcs != NULL; ++funcs)
  {
    for (idx= 0; idx < total; idx++)
    {
      if (unlikely(version != plugin_array_version))
      {
        mysql_mutex_lock(&LOCK_plugin);
        for (size_t i=idx; i < total; i++)
          if (plugins[i] && plugins[i]->state & state_mask)
            plugins[i]=0;
        mysql_mutex_unlock(&LOCK_plugin);
      }
      plugin= plugins[idx];
      /* It will stop iterating on first engine error when "func" returns TRUE */
      if (plugin && (*funcs)(thd, plugin_int_to_ref(plugin), arg))
          goto err;
    }
  }

  DBUG_RETURN(FALSE);
err:
  DBUG_RETURN(TRUE);
}

bool plugin_foreach_with_mask(THD *thd, plugin_foreach_func *func,
                              int type, uint state_mask, void *arg)
{
  plugin_foreach_func *funcs[]= { func, NULL };

  return plugin_foreach_with_mask(thd, funcs, type, state_mask, arg);
}

/****************************************************************************
  Internal type declarations for variables support
****************************************************************************/

#undef MYSQL_SYSVAR_NAME
#define MYSQL_SYSVAR_NAME(name) name
#define PLUGIN_VAR_TYPEMASK 0x007f

#define EXTRA_OPTIONS 3 /* options for: 'foo', 'plugin-foo' and NULL */

typedef DECLARE_MYSQL_SYSVAR_BASIC(sysvar_bool_t, my_bool);
typedef DECLARE_MYSQL_THDVAR_BASIC(thdvar_bool_t, my_bool);
typedef DECLARE_MYSQL_SYSVAR_BASIC(sysvar_str_t, char *);
typedef DECLARE_MYSQL_THDVAR_BASIC(thdvar_str_t, char *);

typedef DECLARE_MYSQL_SYSVAR_TYPELIB(sysvar_enum_t, unsigned long);
typedef DECLARE_MYSQL_THDVAR_TYPELIB(thdvar_enum_t, unsigned long);
typedef DECLARE_MYSQL_SYSVAR_TYPELIB(sysvar_set_t, ulonglong);
typedef DECLARE_MYSQL_THDVAR_TYPELIB(thdvar_set_t, ulonglong);

typedef DECLARE_MYSQL_SYSVAR_SIMPLE(sysvar_int_t, int);
typedef DECLARE_MYSQL_SYSVAR_SIMPLE(sysvar_long_t, long);
typedef DECLARE_MYSQL_SYSVAR_SIMPLE(sysvar_longlong_t, longlong);
typedef DECLARE_MYSQL_SYSVAR_SIMPLE(sysvar_uint_t, uint);
typedef DECLARE_MYSQL_SYSVAR_SIMPLE(sysvar_ulong_t, ulong);
typedef DECLARE_MYSQL_SYSVAR_SIMPLE(sysvar_ulonglong_t, ulonglong);
typedef DECLARE_MYSQL_SYSVAR_SIMPLE(sysvar_double_t, double);

typedef DECLARE_MYSQL_THDVAR_SIMPLE(thdvar_int_t, int);
typedef DECLARE_MYSQL_THDVAR_SIMPLE(thdvar_long_t, long);
typedef DECLARE_MYSQL_THDVAR_SIMPLE(thdvar_longlong_t, longlong);
typedef DECLARE_MYSQL_THDVAR_SIMPLE(thdvar_uint_t, uint);
typedef DECLARE_MYSQL_THDVAR_SIMPLE(thdvar_ulong_t, ulong);
typedef DECLARE_MYSQL_THDVAR_SIMPLE(thdvar_ulonglong_t, ulonglong);
typedef DECLARE_MYSQL_THDVAR_SIMPLE(thdvar_double_t, double);


/****************************************************************************
  default variable data check and update functions
****************************************************************************/

static int check_func_bool(THD *thd, st_mysql_sys_var *var,
                           void *save, st_mysql_value *value)
{
  char buff[STRING_BUFFER_USUAL_SIZE];
  const char *str;
  int result, length;
  long long tmp;

  if (value->value_type(value) == MYSQL_VALUE_TYPE_STRING)
  {
    length= sizeof(buff);
    if (!(str= value->val_str(value, buff, &length)) ||
        (result= find_type(&bool_typelib, str, length, 1)-1) < 0)
      goto err;
  }
  else
  {
    if (value->val_int(value, &tmp) < 0)
      goto err;
    if (tmp > 1)
      goto err;
    result= (int) tmp;
  }
  *(my_bool *) save= result ? TRUE : FALSE;
  return 0;
err:
  return 1;
}


static int check_func_int(THD *thd, st_mysql_sys_var *var,
                          void *save, st_mysql_value *value)
{
  my_bool fixed1, fixed2;
  long long orig, val;
  struct my_option options;
  value->val_int(value, &orig);
  val= orig;
  plugin_opt_set_limits(&options, var);

  if (var->flags & PLUGIN_VAR_UNSIGNED)
  {
    if ((fixed1= (!value->is_unsigned(value) && val < 0)))
      val=0;
    *(uint *)save= (uint) getopt_ull_limit_value((ulonglong) val, &options,
                                                   &fixed2);
  }
  else
  {
    if ((fixed1= (value->is_unsigned(value) && val < 0)))
      val=LLONG_MAX;
    *(int *)save= (int) getopt_ll_limit_value(val, &options, &fixed2);
  }

  return throw_bounds_warning(thd, var->name, fixed1 || fixed2,
                              value->is_unsigned(value), orig);
}


static int check_func_long(THD *thd, st_mysql_sys_var *var,
                          void *save, st_mysql_value *value)
{
  my_bool fixed1, fixed2;
  long long orig, val;
  struct my_option options;
  value->val_int(value, &orig);
  val= orig;
  plugin_opt_set_limits(&options, var);

  if (var->flags & PLUGIN_VAR_UNSIGNED)
  {
    if ((fixed1= (!value->is_unsigned(value) && val < 0)))
      val=0;
    *(ulong *)save= (ulong) getopt_ull_limit_value((ulonglong) val, &options,
                                                   &fixed2);
  }
  else
  {
    if ((fixed1= (value->is_unsigned(value) && val < 0)))
      val=LLONG_MAX;
    *(long *)save= (long) getopt_ll_limit_value(val, &options, &fixed2);
  }

  return throw_bounds_warning(thd, var->name, fixed1 || fixed2,
                              value->is_unsigned(value), orig);
}


static int check_func_longlong(THD *thd, st_mysql_sys_var *var,
                               void *save, st_mysql_value *value)
{
  my_bool fixed1, fixed2;
  long long orig, val;
  struct my_option options;
  value->val_int(value, &orig);
  val= orig;
  plugin_opt_set_limits(&options, var);

  if (var->flags & PLUGIN_VAR_UNSIGNED)
  {
    if ((fixed1= (!value->is_unsigned(value) && val < 0)))
      val=0;
    *(ulonglong *)save= getopt_ull_limit_value((ulonglong) val, &options,
                                               &fixed2);
  }
  else
  {
    if ((fixed1= (value->is_unsigned(value) && val < 0)))
      val=LLONG_MAX;
    *(longlong *)save= getopt_ll_limit_value(val, &options, &fixed2);
  }

  return throw_bounds_warning(thd, var->name, fixed1 || fixed2,
                              value->is_unsigned(value), orig);
}

static int check_func_str(THD *thd, st_mysql_sys_var *var,
                          void *save, st_mysql_value *value)
{
  char buff[STRING_BUFFER_USUAL_SIZE];
  const char *str;
  int length;

  length= sizeof(buff);
  if ((str= value->val_str(value, buff, &length)))
    str= thd->strmake(str, length);
  *(const char**)save= str;
  return 0;
}


static int check_func_enum(THD *thd, st_mysql_sys_var *var,
                           void *save, st_mysql_value *value)
{
  char buff[STRING_BUFFER_USUAL_SIZE];
  const char *str;
  TYPELIB *typelib;
  long long tmp;
  long result;
  int length;

  if (var->flags & PLUGIN_VAR_THDLOCAL)
    typelib= ((thdvar_enum_t*) var)->typelib;
  else
    typelib= ((sysvar_enum_t*) var)->typelib;

  if (value->value_type(value) == MYSQL_VALUE_TYPE_STRING)
  {
    length= sizeof(buff);
    if (!(str= value->val_str(value, buff, &length)))
      goto err;
    if ((result= (long)find_type(typelib, str, length, 0) - 1) < 0)
      goto err;
  }
  else
  {
    if (value->val_int(value, &tmp))
      goto err;
    if (tmp < 0 || tmp >= typelib->count)
      goto err;
    result= (long) tmp;
  }
  *(long*)save= result;
  return 0;
err:
  return 1;
}


static int check_func_set(THD *thd, st_mysql_sys_var *var,
                          void *save, st_mysql_value *value)
{
  char buff[STRING_BUFFER_USUAL_SIZE], *error= 0;
  const char *str;
  TYPELIB *typelib;
  ulonglong result;
  uint error_len= 0;                            // init as only set on error
  bool not_used;
  int length;

  if (var->flags & PLUGIN_VAR_THDLOCAL)
    typelib= ((thdvar_set_t*) var)->typelib;
  else
    typelib= ((sysvar_set_t*)var)->typelib;

  if (value->value_type(value) == MYSQL_VALUE_TYPE_STRING)
  {
    length= sizeof(buff);
    if (!(str= value->val_str(value, buff, &length)))
      goto err;
    result= find_set(typelib, str, length, NULL,
                     &error, &error_len, &not_used);
    if (error_len)
      goto err;
  }
  else
  {
    if (value->val_int(value, (long long *)&result))
      goto err;
    if (unlikely((result >= (1ULL << typelib->count)) &&
                 (typelib->count < sizeof(long)*8)))
      goto err;
  }
  *(ulonglong*)save= result;
  return 0;
err:
  return 1;
}

static int check_func_double(THD *thd, st_mysql_sys_var *var,
                             void *save, st_mysql_value *value)
{
  double v;
  my_bool fixed;
  struct my_option option;

  value->val_real(value, &v);
  plugin_opt_set_limits(&option, var);
  *(double *) save= getopt_double_limit_value(v, &option, &fixed);

  return throw_bounds_warning(thd, var->name, fixed, v);
}


static void update_func_bool(THD *thd, st_mysql_sys_var *var,
                             void *tgt, const void *save)
{
  *(my_bool *) tgt= *(my_bool *) save ? TRUE : FALSE;
}


static void update_func_int(THD *thd, st_mysql_sys_var *var,
                             void *tgt, const void *save)
{
  *(int *)tgt= *(int *) save;
}


static void update_func_long(THD *thd, st_mysql_sys_var *var,
                             void *tgt, const void *save)
{
  *(long *)tgt= *(long *) save;
}


static void update_func_longlong(THD *thd, st_mysql_sys_var *var,
                             void *tgt, const void *save)
{
  *(longlong *)tgt= *(ulonglong *) save;
}


static void update_func_str(THD *thd, st_mysql_sys_var *var,
                             void *tgt, const void *save)
{
  *(char **) tgt= *(char **) save;
}

static void update_func_double(THD *thd, st_mysql_sys_var *var,
                               void *tgt, const void *save)
{
  *(double *) tgt= *(double *) save;
}

/****************************************************************************
  System Variables support
****************************************************************************/
/*
  This function is not thread safe as the pointer returned at the end of
  the function is outside mutex.
*/

void lock_plugin_mutex()
{
  mysql_mutex_lock(&LOCK_plugin);
}

void unlock_plugin_mutex()
{
  mysql_mutex_unlock(&LOCK_plugin);
}

sys_var *find_sys_var_ex(THD *thd, const char *str, size_t length,
                         bool throw_error, bool locked)
{
  sys_var *var;
  sys_var_pluginvar *pi= NULL;
  plugin_ref plugin;
  DBUG_ENTER("find_sys_var_ex");

  if (!locked)
    mysql_mutex_lock(&LOCK_plugin);
  mysql_rwlock_rdlock(&LOCK_system_variables_hash);
  if ((var= intern_find_sys_var(str, length)) &&
      (pi= var->cast_pluginvar()))
  {
    mysql_rwlock_unlock(&LOCK_system_variables_hash);
    LEX *lex= thd ? thd->lex : 0;
    if (!(plugin= my_intern_plugin_lock(lex, plugin_int_to_ref(pi->plugin))))
      var= NULL; /* failed to lock it, it must be uninstalling */
    else
    if (!(plugin_state(plugin) & PLUGIN_IS_READY))
    {
      /* initialization not completed */
      var= NULL;
      intern_plugin_unlock(lex, plugin);
    }
  }
  else
    mysql_rwlock_unlock(&LOCK_system_variables_hash);
  if (!locked)
    mysql_mutex_unlock(&LOCK_plugin);

  if (!throw_error && !var)
    my_error(ER_UNKNOWN_SYSTEM_VARIABLE, MYF(0), (char*) str);
  DBUG_RETURN(var);
}


sys_var *find_sys_var(THD *thd, const char *str, size_t length)
{
  return find_sys_var_ex(thd, str, length, false, false);
}


/*
  called by register_var, construct_options and test_plugin_options.
  Returns the 'bookmark' for the named variable.
  LOCK_system_variables_hash should be at least read locked
*/
static st_bookmark *find_bookmark(const char *plugin, const char *name,
                                  int flags)
{
  st_bookmark *result= NULL;
  size_t namelen, length, pluginlen= 0;
  char *varname, *p;

  if (!(flags & PLUGIN_VAR_THDLOCAL))
    return NULL;

  namelen= strlen(name);
  if (plugin)
    pluginlen= strlen(plugin) + 1;
  length= namelen + pluginlen + 2;
  varname= (char*) my_alloca(length);

  if (plugin)
  {
    strxmov(varname + 1, plugin, "_", name, NullS);
    for (p= varname + 1; *p; p++)
      if (*p == '-')
        *p= '_';
  }
  else
    memcpy(varname + 1, name, namelen + 1);

  varname[0]= flags & PLUGIN_VAR_TYPEMASK;

  result= (st_bookmark*) my_hash_search(&bookmark_hash,
                                        (const uchar*) varname, length - 1);

  return result;
}


/*
  returns a bookmark for thd-local variables, creating if neccessary.
  returns null for non thd-local variables.
  Requires that a write lock is obtained on LOCK_system_variables_hash
*/
static st_bookmark *register_var(const char *plugin, const char *name,
                                 int flags)
{
  size_t length= strlen(plugin) + strlen(name) + 3, size= 0, offset, new_size;
  st_bookmark *result;
  char *varname, *p;

  if (!(flags & PLUGIN_VAR_THDLOCAL))
    return NULL;

  switch (flags & PLUGIN_VAR_TYPEMASK) {
  case PLUGIN_VAR_BOOL:
    size= sizeof(my_bool);
    break;
  case PLUGIN_VAR_INT:
    size= sizeof(int);
    break;
  case PLUGIN_VAR_LONG:
  case PLUGIN_VAR_ENUM:
    size= sizeof(long);
    break;
  case PLUGIN_VAR_LONGLONG:
  case PLUGIN_VAR_SET:
    size= sizeof(ulonglong);
    break;
  case PLUGIN_VAR_STR:
    size= sizeof(char*);
    break;
  case PLUGIN_VAR_DOUBLE:
    size= sizeof(double);
    break;
  default:
    DBUG_ASSERT(0);
    return NULL;
  };

  varname= ((char*) my_alloca(length));
  strxmov(varname + 1, plugin, "_", name, NullS);
  for (p= varname + 1; *p; p++)
    if (*p == '-')
      *p= '_';

  if (!(result= find_bookmark(NULL, varname + 1, flags)))
  {
    result= (st_bookmark*) alloc_root(&plugin_mem_root,
                                      sizeof(st_bookmark) + length-1);
    varname[0]= flags & PLUGIN_VAR_TYPEMASK;
    memcpy(result->key, varname, length);
    result->name_len= length - 2;
    result->offset= -1;

    DBUG_ASSERT(size && !(size & (size-1))); /* must be power of 2 */

    offset= global_system_variables.dynamic_variables_size;
    offset= (offset + size - 1) & ~(size - 1);
    result->offset= (int) offset;

    new_size= (offset + size + 63) & ~63;

    if (new_size > global_variables_dynamic_size)
    {
      global_system_variables.dynamic_variables_ptr= (char*)
        my_realloc(key_memory_global_system_variables,
                   global_system_variables.dynamic_variables_ptr, new_size,
                   MYF(MY_WME | MY_FAE | MY_ALLOW_ZERO_PTR));
      max_system_variables.dynamic_variables_ptr= (char*)
        my_realloc(key_memory_global_system_variables,
                   max_system_variables.dynamic_variables_ptr, new_size,
                   MYF(MY_WME | MY_FAE | MY_ALLOW_ZERO_PTR));
      /*
        Clear the new variable value space. This is required for string
        variables. If their value is non-NULL, it must point to a valid
        string.
      */
      memset(global_system_variables.dynamic_variables_ptr +
             global_variables_dynamic_size, 0,
             new_size - global_variables_dynamic_size);
      memset(max_system_variables.dynamic_variables_ptr +
             global_variables_dynamic_size, 0,
             new_size - global_variables_dynamic_size);
      global_variables_dynamic_size= new_size;
    }

    global_system_variables.dynamic_variables_head= offset;
    max_system_variables.dynamic_variables_head= offset;
    global_system_variables.dynamic_variables_size= offset + size;
    max_system_variables.dynamic_variables_size= offset + size;
    global_system_variables.dynamic_variables_version++;
    max_system_variables.dynamic_variables_version++;

    result->version= global_system_variables.dynamic_variables_version;

    /* this should succeed because we have already checked if a dup exists */
    if (my_hash_insert(&bookmark_hash, (uchar*) result))
    {
      fprintf(stderr, "failed to add placeholder to hash");
      DBUG_ASSERT(0);
    }

    /*
      Hashing vars of string type with MEMALLOC flag.
    */
    if (((flags & PLUGIN_VAR_TYPEMASK) == PLUGIN_VAR_STR) &&
        (flags & PLUGIN_VAR_MEMALLOC) &&
        (my_hash_insert(&malloced_string_type_sysvars_bookmark_hash,
                        (uchar *)result)))
    {
      fprintf(stderr, "failed to add placeholder to"
                      " hash of malloced string type sysvars");
      DBUG_ASSERT(0);
    }
  }
  return result;
}

static void restore_pluginvar_names(sys_var *first)
{
  for (sys_var *var= first; var; var= var->next)
  {
    sys_var_pluginvar *pv= var->cast_pluginvar();
    pv->plugin_var->name= pv->orig_pluginvar_name;
  }
}


/**
  Allocate memory and copy dynamic variables from global system variables
  to per-thread system variables copy.

  @param thd              thread context
  @param global_lock      If true LOCK_global_system_variables should be
                          acquired while copying variables from global
                          variables copy.
*/
void alloc_and_copy_thd_dynamic_variables(THD *thd, bool global_lock)
{
  uint idx;

  mysql_rwlock_rdlock(&LOCK_system_variables_hash);

  if (global_lock)
    mysql_mutex_lock(&LOCK_global_system_variables);

  mysql_mutex_assert_owner(&LOCK_global_system_variables);

  /*
    MAINTAINER:
    The following assert is wrong on purpose, useful to debug
    when thd dynamic variables are expanded:
    DBUG_ASSERT(thd->variables.dynamic_variables_ptr == NULL);
  */

  thd->variables.dynamic_variables_ptr= (char*)
    my_realloc(key_memory_THD_variables,
               thd->variables.dynamic_variables_ptr,
               global_variables_dynamic_size,
               MYF(MY_WME | MY_FAE | MY_ALLOW_ZERO_PTR));

  /*
    Debug hook which allows tests to check that this code is not
    called for InnoDB after connection was created.
  */
  DBUG_EXECUTE_IF("verify_innodb_thdvars", DBUG_ASSERT(0););

  memcpy(thd->variables.dynamic_variables_ptr +
         thd->variables.dynamic_variables_size,
         global_system_variables.dynamic_variables_ptr +
         thd->variables.dynamic_variables_size,
         global_system_variables.dynamic_variables_size -
         thd->variables.dynamic_variables_size);

  /*
    Iterate through newly copied vars of string type with MEMALLOC
    flag and strdup value.
  */
  for (idx= 0; idx < malloced_string_type_sysvars_bookmark_hash.records; idx++)
  {
    sys_var_pluginvar *pi;
    sys_var *var;
    int varoff;
    char **thdvar, **sysvar;
    st_bookmark *v=
      (st_bookmark*)my_hash_element(&malloced_string_type_sysvars_bookmark_hash,
                                    idx);

    if (v->version <= thd->variables.dynamic_variables_version ||
        !(var= intern_find_sys_var(v->key + 1, v->name_len)) ||
        !(pi= var->cast_pluginvar()) ||
        v->key[0] != (pi->plugin_var->flags & PLUGIN_VAR_TYPEMASK))
      continue;

    varoff= *(int *) (pi->plugin_var + 1);
    thdvar= (char **) (thd->variables.
                       dynamic_variables_ptr + varoff);
    sysvar= (char **) (global_system_variables.
                       dynamic_variables_ptr + varoff);
    *thdvar= NULL;
    plugin_var_memalloc_session_update(thd, NULL, thdvar, *sysvar);
  }

  if (global_lock)
    mysql_mutex_unlock(&LOCK_global_system_variables);

  thd->variables.dynamic_variables_version=
    global_system_variables.dynamic_variables_version;
  thd->variables.dynamic_variables_head=
    global_system_variables.dynamic_variables_head;
  thd->variables.dynamic_variables_size=
    global_system_variables.dynamic_variables_size;

  mysql_rwlock_unlock(&LOCK_system_variables_hash);
}


/*
  returns a pointer to the memory which holds the thd-local variable or
  a pointer to the global variable if thd==null.
  If required, will sync with global variables if the requested variable
  has not yet been allocated in the current thread.
*/
static uchar *intern_sys_var_ptr(THD* thd, int offset, bool global_lock)
{
  DBUG_ASSERT(offset >= 0);
  DBUG_ASSERT((uint)offset <= global_system_variables.dynamic_variables_head);

  if (!thd)
    return (uchar*) global_system_variables.dynamic_variables_ptr + offset;

  /*
    dynamic_variables_head points to the largest valid offset
  */
  if (!thd->variables.dynamic_variables_ptr ||
      (uint)offset > thd->variables.dynamic_variables_head)
  {
    /* Current THD only. Don't trigger resync on remote THD. */
    if (current_thd == thd)
      alloc_and_copy_thd_dynamic_variables(thd, global_lock);
    else
      return (uchar*) global_system_variables.dynamic_variables_ptr + offset;
  }

  return (uchar*)thd->variables.dynamic_variables_ptr + offset;
}


/**
  For correctness and simplicity's sake, a pointer to a function
  must be compatible with pointed-to type, that is, the return and
  parameters types must be the same. Thus, a callback function is
  defined for each scalar type. The functions are assigned in
  construct_options to their respective types.
*/

static char *mysql_sys_var_char(THD* thd, int offset)
{
  return (char *) intern_sys_var_ptr(thd, offset, true);
}

static int *mysql_sys_var_int(THD* thd, int offset)
{
  return (int *) intern_sys_var_ptr(thd, offset, true);
}

static long *mysql_sys_var_long(THD* thd, int offset)
{
  return (long *) intern_sys_var_ptr(thd, offset, true);
}

static unsigned long *mysql_sys_var_ulong(THD* thd, int offset)
{
  return (unsigned long *) intern_sys_var_ptr(thd, offset, true);
}

static long long *mysql_sys_var_longlong(THD* thd, int offset)
{
  return (long long *) intern_sys_var_ptr(thd, offset, true);
}

static unsigned long long *mysql_sys_var_ulonglong(THD* thd, int offset)
{
  return (unsigned long long *) intern_sys_var_ptr(thd, offset, true);
}

static char **mysql_sys_var_str(THD* thd, int offset)
{
  return (char **) intern_sys_var_ptr(thd, offset, true);
}

static double *mysql_sys_var_double(THD* thd, int offset)
{
  return (double *) intern_sys_var_ptr(thd, offset, true);
}

void plugin_thdvar_init(THD *thd, bool enable_plugins)
{
  plugin_ref old_table_plugin= thd->variables.table_plugin;
  plugin_ref old_temp_table_plugin= thd->variables.temp_table_plugin;
  DBUG_ENTER("plugin_thdvar_init");

  thd->variables.table_plugin= NULL;
  thd->variables.temp_table_plugin= NULL;
  cleanup_variables(thd, &thd->variables);

  thd->variables= global_system_variables;
  thd->variables.table_plugin= NULL;
  thd->variables.temp_table_plugin= NULL;

  thd->variables.dynamic_variables_version= 0;
  thd->variables.dynamic_variables_size= 0;
  thd->variables.dynamic_variables_ptr= 0;

  if (enable_plugins)
  {
    mysql_mutex_lock(&LOCK_plugin);
    thd->variables.table_plugin=
      my_intern_plugin_lock(NULL, global_system_variables.table_plugin);
    intern_plugin_unlock(NULL, old_table_plugin);
    thd->variables.temp_table_plugin=
      my_intern_plugin_lock(NULL, global_system_variables.temp_table_plugin);
    intern_plugin_unlock(NULL, old_temp_table_plugin);
    mysql_mutex_unlock(&LOCK_plugin);
  }

  /* Initialize all Sys_var_charptr variables here. */

  // @@session.session_track_system_variables
  thd->session_sysvar_res_mgr.init(&thd->variables.track_sysvars_ptr, thd->charset());

  DBUG_VOID_RETURN;
}


/*
  Unlocks all system variables which hold a reference
*/
static void unlock_variables(THD *thd, struct system_variables *vars)
{
  intern_plugin_unlock(NULL, vars->table_plugin);
  intern_plugin_unlock(NULL, vars->temp_table_plugin);
  vars->table_plugin= NULL;
  vars->temp_table_plugin= NULL;
}


/*
  Frees memory used by system variables

  Unlike plugin_vars_free_values() it frees all variables of all plugins,
  it's used on shutdown.
*/
static void cleanup_variables(THD *thd, struct system_variables *vars)
{
  if (thd)
  {
    /* Block the Performance Schema from accessing THD::variables. */
    mysql_mutex_lock(&thd->LOCK_thd_data);

    plugin_var_memalloc_free(&thd->variables);
    /* Remove references to session_sysvar_res_mgr memory before freeing it. */
    thd->variables.track_sysvars_ptr = NULL;
    thd->session_sysvar_res_mgr.deinit();
  }
  DBUG_ASSERT(vars->table_plugin == NULL);
  DBUG_ASSERT(vars->temp_table_plugin == NULL);

  my_free(vars->dynamic_variables_ptr);
  vars->dynamic_variables_ptr= NULL;
  vars->dynamic_variables_size= 0;
  vars->dynamic_variables_version= 0;

  if (thd)
    mysql_mutex_unlock(&thd->LOCK_thd_data);
}


void plugin_thdvar_cleanup(THD *thd, bool enable_plugins)
{
  DBUG_ENTER("plugin_thdvar_cleanup");

  if (enable_plugins)
  {
    Mutex_lock plugin_lock(&LOCK_plugin);
    unlock_variables(thd, &thd->variables);
    size_t idx;
    if ((idx= thd->lex->plugins.size()))
    {
      plugin_ref *list= thd->lex->plugins.end() - 1;
      DBUG_PRINT("info",("unlocking %u plugins", static_cast<uint>(idx)));
      while (list >= thd->lex->plugins.begin())
        intern_plugin_unlock(thd->lex, *list--);
    }

    reap_plugins();
    thd->lex->plugins.clear();
  }
  cleanup_variables(thd, &thd->variables);

  DBUG_VOID_RETURN;
}


/**
  @brief Free values of thread variables of a plugin.

  This must be called before a plugin is deleted. Otherwise its
  variables are no longer accessible and the value space is lost. Note
  that only string values with PLUGIN_VAR_MEMALLOC are allocated and
  must be freed.

  @param[in]        vars        Chain of system variables of a plugin
*/

static void plugin_vars_free_values(sys_var *vars)
{
  DBUG_ENTER("plugin_vars_free_values");

  for (sys_var *var= vars; var; var= var->next)
  {
    sys_var_pluginvar *piv= var->cast_pluginvar();
    if (piv &&
        ((piv->plugin_var->flags & PLUGIN_VAR_TYPEMASK) == PLUGIN_VAR_STR) &&
        (piv->plugin_var->flags & PLUGIN_VAR_MEMALLOC))
    {
      /* Free the string from global_system_variables. */
      char **valptr= (char**) piv->real_value_ptr(NULL, OPT_GLOBAL);
      DBUG_PRINT("plugin", ("freeing value for: '%s'  addr: 0x%lx",
                            var->name.str, (long) valptr));
      my_free(*valptr);
      *valptr= NULL;
    }
  }
  DBUG_VOID_RETURN;
}

static SHOW_TYPE pluginvar_show_type(st_mysql_sys_var *plugin_var)
{
  switch (plugin_var->flags & PLUGIN_VAR_TYPEMASK) {
  case PLUGIN_VAR_BOOL:
    return SHOW_MY_BOOL;
  case PLUGIN_VAR_INT:
    return SHOW_INT;
  case PLUGIN_VAR_LONG:
    return SHOW_LONG;
  case PLUGIN_VAR_LONGLONG:
    return SHOW_LONGLONG;
  case PLUGIN_VAR_STR:
    return SHOW_CHAR_PTR;
  case PLUGIN_VAR_ENUM:
  case PLUGIN_VAR_SET:
    return SHOW_CHAR;
  case PLUGIN_VAR_DOUBLE:
    return SHOW_DOUBLE;
  default:
    DBUG_ASSERT(0);
    return SHOW_UNDEF;
  }
}


/**
  Set value for thread local variable with PLUGIN_VAR_MEMALLOC flag.

  @param[in]     thd   Thread context.
  @param[in]     var   Plugin variable.
  @param[in,out] dest  Destination memory pointer.
  @param[in]     value '\0'-terminated new value.

  Most plugin variable values are stored on dynamic_variables_ptr.
  Releasing memory occupied by these values is as simple as freeing
  dynamic_variables_ptr.

  An exception to the rule are PLUGIN_VAR_MEMALLOC variables, which
  are stored on individual memory hunks. All of these hunks has to
  be freed when it comes to cleanup.

  It may happen that a plugin was uninstalled and descriptors of
  it's variables are lost. In this case it is impossible to locate
  corresponding values.

  In addition to allocating and setting variable value, new element
  is added to dynamic_variables_allocs list. When thread is done, it
  has to call plugin_var_memalloc_free() to release memory used by
  PLUGIN_VAR_MEMALLOC variables.

  If var is NULL, variable update function is not called. This is
  needed when we take snapshot of system variables during thread
  initialization.

  @note List element and variable value are stored on the same memory
  hunk. List element is followed by variable value.

  @return Completion status
  @retval false Success
  @retval true  Failure
*/

static bool plugin_var_memalloc_session_update(THD *thd,
                                               st_mysql_sys_var *var,
                                               char **dest, const char *value)

{
  LIST *old_element= NULL;
  struct system_variables *vars= &thd->variables;
  DBUG_ENTER("plugin_var_memalloc_session_update");

  if (value)
  {
    size_t length= strlen(value) + 1;
    LIST *element;
    if (!(element= (LIST *) my_malloc(key_memory_THD_variables,
                                      sizeof(LIST) + length, MYF(MY_WME))))
      DBUG_RETURN(true);
    memcpy(element + 1, value, length);
    value= (const char *) (element + 1);
    vars->dynamic_variables_allocs= list_add(vars->dynamic_variables_allocs,
                                             element);
  }

  if (*dest)
    old_element= (LIST *) (*dest - sizeof(LIST));

  if (var)
    var->update(thd, var, (void **) dest, (const void *) &value);
  else
    *dest= (char *) value;

  if (old_element)
  {
    vars->dynamic_variables_allocs= list_delete(vars->dynamic_variables_allocs,
                                                old_element);
    my_free(old_element);
  }
  DBUG_RETURN(false);
}


/**
  Free all elements allocated by plugin_var_memalloc_session_update().

  @param[in]     vars  system variables structure

  @see plugin_var_memalloc_session_update
*/

static void plugin_var_memalloc_free(struct system_variables *vars)
{
  LIST *next, *root;
  DBUG_ENTER("plugin_var_memalloc_free");
  for (root= vars->dynamic_variables_allocs; root; root= next)
  {
    next= root->next;
    my_free(root);
  }
  vars->dynamic_variables_allocs= NULL;
  DBUG_VOID_RETURN;
}


/**
  Set value for global variable with PLUGIN_VAR_MEMALLOC flag.

  @param[in]     thd   Thread context.
  @param[in]     var   Plugin variable.
  @param[in,out] dest  Destination memory pointer.
  @param[in]     value '\0'-terminated new value.

  @return Completion status
  @retval false Success
  @retval true  Failure
*/

static bool plugin_var_memalloc_global_update(THD *thd,
                                              st_mysql_sys_var *var,
                                              char **dest, const char *value)
{
  char *old_value= *dest;
  DBUG_EXECUTE_IF("simulate_bug_20292712", my_sleep(1000););
  DBUG_ENTER("plugin_var_memalloc_global_update");

  if (value && !(value= my_strdup(key_memory_global_system_variables,
                                  value, MYF(MY_WME))))
    DBUG_RETURN(true);

  var->update(thd, var, (void **) dest, (const void *) &value);

  if (old_value)
    my_free(old_value);

  DBUG_RETURN(false);
}


bool sys_var_pluginvar::check_update_type(Item_result type)
{
  switch (plugin_var->flags & PLUGIN_VAR_TYPEMASK) {
  case PLUGIN_VAR_INT:
  case PLUGIN_VAR_LONG:
  case PLUGIN_VAR_LONGLONG:
    return type != INT_RESULT;
  case PLUGIN_VAR_STR:
    return type != STRING_RESULT;
  case PLUGIN_VAR_ENUM:
  case PLUGIN_VAR_BOOL:
  case PLUGIN_VAR_SET:
    return type != STRING_RESULT && type != INT_RESULT;
  case PLUGIN_VAR_DOUBLE:
    return type != INT_RESULT && type != REAL_RESULT && type != DECIMAL_RESULT;
  default:
    return true;
  }
}


uchar* sys_var_pluginvar::real_value_ptr(THD *thd, enum_var_type type)
{
  DBUG_ASSERT(thd || (type == OPT_GLOBAL));
  if (plugin_var->flags & PLUGIN_VAR_THDLOCAL)
  {
    if (type == OPT_GLOBAL)
      thd= NULL;

    return intern_sys_var_ptr(thd, *(int*) (plugin_var+1), false);
  }
  return *(uchar**) (plugin_var+1);
}


TYPELIB* sys_var_pluginvar::plugin_var_typelib(void)
{
  switch (plugin_var->flags & (PLUGIN_VAR_TYPEMASK | PLUGIN_VAR_THDLOCAL)) {
  case PLUGIN_VAR_ENUM:
    return ((sysvar_enum_t *)plugin_var)->typelib;
  case PLUGIN_VAR_SET:
    return ((sysvar_set_t *)plugin_var)->typelib;
  case PLUGIN_VAR_ENUM | PLUGIN_VAR_THDLOCAL:
    return ((thdvar_enum_t *)plugin_var)->typelib;
  case PLUGIN_VAR_SET | PLUGIN_VAR_THDLOCAL:
    return ((thdvar_set_t *)plugin_var)->typelib;
  default:
    return NULL;
  }
  return NULL;	/* Keep compiler happy */
}


uchar* sys_var_pluginvar::do_value_ptr(THD *running_thd, THD *target_thd, enum_var_type type,
                                       LEX_STRING *base)
{
  uchar* result;

  result= real_value_ptr(target_thd, type);

  if ((plugin_var->flags & PLUGIN_VAR_TYPEMASK) == PLUGIN_VAR_ENUM)
    result= (uchar*) get_type(plugin_var_typelib(), *(ulong*)result);
  else if ((plugin_var->flags & PLUGIN_VAR_TYPEMASK) == PLUGIN_VAR_SET)
    result= (uchar*) set_to_string(running_thd, 0, *(ulonglong*) result,
                                   plugin_var_typelib()->type_names);
  return result;
}

bool sys_var_pluginvar::do_check(THD *thd, set_var *var)
{
  st_item_value_holder value;
  DBUG_ASSERT(!is_readonly());
  DBUG_ASSERT(plugin_var->check);

  value.value_type= item_value_type;
  value.val_str= item_val_str;
  value.val_int= item_val_int;
  value.val_real= item_val_real;
  value.is_unsigned= item_is_unsigned;
  value.item= var->value;

  return plugin_var->check(thd, plugin_var, &var->save_result, &value);
}

bool sys_var_pluginvar::session_update(THD *thd, set_var *var)
{
  bool rc= false;
  DBUG_ASSERT(!is_readonly());
  DBUG_ASSERT(plugin_var->flags & PLUGIN_VAR_THDLOCAL);
  DBUG_ASSERT(thd == current_thd);

  mysql_mutex_lock(&LOCK_global_system_variables);
  void *tgt= real_value_ptr(thd, var->type);
  const void *src= var->value ? (void*)&var->save_result
                              : (void*)real_value_ptr(thd, OPT_GLOBAL);
  mysql_mutex_unlock(&LOCK_global_system_variables);

  if ((plugin_var->flags & PLUGIN_VAR_TYPEMASK) == PLUGIN_VAR_STR &&
      plugin_var->flags & PLUGIN_VAR_MEMALLOC)
    rc= plugin_var_memalloc_session_update(thd, plugin_var, (char **) tgt,
                                           *(const char **) src);
  else
    plugin_var->update(thd, plugin_var, tgt, src);

  return rc;
}

bool sys_var_pluginvar::global_update(THD *thd, set_var *var)
{
  bool rc= false;
  DBUG_ASSERT(!is_readonly());
  mysql_mutex_assert_owner(&LOCK_global_system_variables);

  void *tgt= real_value_ptr(thd, var->type);
  const void *src= &var->save_result;

  if (!var->value)
  {
    switch (plugin_var->flags & (PLUGIN_VAR_TYPEMASK | PLUGIN_VAR_THDLOCAL)) {
    case PLUGIN_VAR_INT:
      src= &((sysvar_uint_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_LONG:
      src= &((sysvar_ulong_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_LONGLONG:
      src= &((sysvar_ulonglong_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_ENUM:
      src= &((sysvar_enum_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_SET:
      src= &((sysvar_set_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_BOOL:
      src= &((sysvar_bool_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_STR:
      src= &((sysvar_str_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_DOUBLE:
      src= &((sysvar_double_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_INT | PLUGIN_VAR_THDLOCAL:
      src= &((thdvar_uint_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_LONG | PLUGIN_VAR_THDLOCAL:
      src= &((thdvar_ulong_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_LONGLONG | PLUGIN_VAR_THDLOCAL:
      src= &((thdvar_ulonglong_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_ENUM | PLUGIN_VAR_THDLOCAL:
      src= &((thdvar_enum_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_SET | PLUGIN_VAR_THDLOCAL:
      src= &((thdvar_set_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_BOOL | PLUGIN_VAR_THDLOCAL:
      src= &((thdvar_bool_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_STR | PLUGIN_VAR_THDLOCAL:
      src= &((thdvar_str_t*) plugin_var)->def_val;
      break;
    case PLUGIN_VAR_DOUBLE | PLUGIN_VAR_THDLOCAL:
      src= &((thdvar_double_t*) plugin_var)->def_val;
      break;
    default:
      DBUG_ASSERT(0);
    }
  }

  if ((plugin_var->flags & PLUGIN_VAR_TYPEMASK) == PLUGIN_VAR_STR &&
      plugin_var->flags & PLUGIN_VAR_MEMALLOC)
    rc= plugin_var_memalloc_global_update(thd, plugin_var, (char **) tgt,
                                          *(const char **) src);
  else
    plugin_var->update(thd, plugin_var, tgt, src);

  return rc;
}


/**
  Enforce the NO DEFAULT policy for plugin system variables

  A plugin variable does not explicitly call the plugin supplied check function
  when setting the default value, e.g. SET <plugin_var> = DEFAULT.

  But when the PLUGIN_VAR_NODEFAULT is set setting the default value is
  prohibited.
  This function gets called after the actual check done by
  sys_var_pluginvar::do_check() so it does not need to check again.

  it only needs to enforce the PLUGIN_VAR_NODEFAULT flag.

  There's no need for special error hence just returning true is enough.

  @sa sys_var::on_check_function, sys_var::check,
    sys_var_pluginvar::do_check(), PLUGIN_VAR_NODEFAULT

  @param self   the sys_var structure for the variable being set
  @param THD    the current thread
  @param var    the data about the value being set
  @return is the setting valid
  @retval true not valid
  @retval false valid
*/
bool sys_var_pluginvar::on_check_pluginvar(sys_var *self, THD *thd, set_var *var)
{
  /* This handler is installed only if NO_DEFAULT is specified */
  DBUG_ASSERT(((sys_var_pluginvar *) self)->plugin_var->flags &
              PLUGIN_VAR_NODEFAULT);

  return (!var->value);
}


#define OPTION_SET_LIMITS(type, options, opt) \
  options->var_type= type; \
  options->def_value= (opt)->def_val; \
  options->min_value= (opt)->min_val; \
  options->max_value= (opt)->max_val; \
  options->block_size= (long) (opt)->blk_sz

#define OPTION_SET_LIMITS_DOUBLE(options, opt) \
  options->var_type= GET_DOUBLE; \
  options->def_value= (longlong) getopt_double2ulonglong((opt)->def_val); \
  options->min_value= (longlong) getopt_double2ulonglong((opt)->min_val); \
  options->max_value= getopt_double2ulonglong((opt)->max_val); \
  options->block_size= (long) (opt)->blk_sz;


static void plugin_opt_set_limits(struct my_option *options,
                                  const st_mysql_sys_var *opt)
{
  options->sub_size= 0;

  switch (opt->flags & (PLUGIN_VAR_TYPEMASK |
                        PLUGIN_VAR_UNSIGNED | PLUGIN_VAR_THDLOCAL)) {
  /* global system variables */
  case PLUGIN_VAR_INT:
    OPTION_SET_LIMITS(GET_INT, options, (sysvar_int_t*) opt);
    break;
  case PLUGIN_VAR_INT | PLUGIN_VAR_UNSIGNED:
    OPTION_SET_LIMITS(GET_UINT, options, (sysvar_uint_t*) opt);
    break;
  case PLUGIN_VAR_LONG:
    OPTION_SET_LIMITS(GET_LONG, options, (sysvar_long_t*) opt);
    break;
  case PLUGIN_VAR_LONG | PLUGIN_VAR_UNSIGNED:
    OPTION_SET_LIMITS(GET_ULONG, options, (sysvar_ulong_t*) opt);
    break;
  case PLUGIN_VAR_LONGLONG:
    OPTION_SET_LIMITS(GET_LL, options, (sysvar_longlong_t*) opt);
    break;
  case PLUGIN_VAR_LONGLONG | PLUGIN_VAR_UNSIGNED:
    OPTION_SET_LIMITS(GET_ULL, options, (sysvar_ulonglong_t*) opt);
    break;
  case PLUGIN_VAR_ENUM:
    options->var_type= GET_ENUM;
    options->typelib= ((sysvar_enum_t*) opt)->typelib;
    options->def_value= ((sysvar_enum_t*) opt)->def_val;
    options->min_value= options->block_size= 0;
    options->max_value= options->typelib->count - 1;
    break;
  case PLUGIN_VAR_SET:
    options->var_type= GET_SET;
    options->typelib= ((sysvar_set_t*) opt)->typelib;
    options->def_value= ((sysvar_set_t*) opt)->def_val;
    options->min_value= options->block_size= 0;
    options->max_value= (1ULL << options->typelib->count) - 1;
    break;
  case PLUGIN_VAR_BOOL:
    options->var_type= GET_BOOL;
    options->def_value= ((sysvar_bool_t*) opt)->def_val;
    break;
  case PLUGIN_VAR_STR:
    options->var_type= ((opt->flags & PLUGIN_VAR_MEMALLOC) ?
                        GET_STR_ALLOC : GET_STR);
    options->def_value= (intptr) ((sysvar_str_t*) opt)->def_val;
    break;
  case PLUGIN_VAR_DOUBLE:
    OPTION_SET_LIMITS_DOUBLE(options, (sysvar_double_t*) opt);
    break;
  /* threadlocal variables */
  case PLUGIN_VAR_INT | PLUGIN_VAR_THDLOCAL:
    OPTION_SET_LIMITS(GET_INT, options, (thdvar_int_t*) opt);
    break;
  case PLUGIN_VAR_INT | PLUGIN_VAR_UNSIGNED | PLUGIN_VAR_THDLOCAL:
    OPTION_SET_LIMITS(GET_UINT, options, (thdvar_uint_t*) opt);
    break;
  case PLUGIN_VAR_LONG | PLUGIN_VAR_THDLOCAL:
    OPTION_SET_LIMITS(GET_LONG, options, (thdvar_long_t*) opt);
    break;
  case PLUGIN_VAR_LONG | PLUGIN_VAR_UNSIGNED | PLUGIN_VAR_THDLOCAL:
    OPTION_SET_LIMITS(GET_ULONG, options, (thdvar_ulong_t*) opt);
    break;
  case PLUGIN_VAR_LONGLONG | PLUGIN_VAR_THDLOCAL:
    OPTION_SET_LIMITS(GET_LL, options, (thdvar_longlong_t*) opt);
    break;
  case PLUGIN_VAR_LONGLONG | PLUGIN_VAR_UNSIGNED | PLUGIN_VAR_THDLOCAL:
    OPTION_SET_LIMITS(GET_ULL, options, (thdvar_ulonglong_t*) opt);
    break;
  case PLUGIN_VAR_DOUBLE | PLUGIN_VAR_THDLOCAL:
    OPTION_SET_LIMITS_DOUBLE(options, (thdvar_double_t*) opt);
    break;
  case PLUGIN_VAR_ENUM | PLUGIN_VAR_THDLOCAL:
    options->var_type= GET_ENUM;
    options->typelib= ((thdvar_enum_t*) opt)->typelib;
    options->def_value= ((thdvar_enum_t*) opt)->def_val;
    options->min_value= options->block_size= 0;
    options->max_value= options->typelib->count - 1;
    break;
  case PLUGIN_VAR_SET | PLUGIN_VAR_THDLOCAL:
    options->var_type= GET_SET;
    options->typelib= ((thdvar_set_t*) opt)->typelib;
    options->def_value= ((thdvar_set_t*) opt)->def_val;
    options->min_value= options->block_size= 0;
    options->max_value= (1ULL << options->typelib->count) - 1;
    break;
  case PLUGIN_VAR_BOOL | PLUGIN_VAR_THDLOCAL:
    options->var_type= GET_BOOL;
    options->def_value= ((thdvar_bool_t*) opt)->def_val;
    break;
  case PLUGIN_VAR_STR | PLUGIN_VAR_THDLOCAL:
    options->var_type= ((opt->flags & PLUGIN_VAR_MEMALLOC) ?
                        GET_STR_ALLOC : GET_STR);
    options->def_value= (intptr) ((thdvar_str_t*) opt)->def_val;
    break;
  default:
    DBUG_ASSERT(0);
  }
  options->arg_type= REQUIRED_ARG;
  if (opt->flags & PLUGIN_VAR_NOCMDARG)
    options->arg_type= NO_ARG;
  if (opt->flags & PLUGIN_VAR_OPCMDARG)
    options->arg_type= OPT_ARG;
}

extern "C" my_bool get_one_plugin_option(int optid, const struct my_option *,
                                         char *);

my_bool get_one_plugin_option(int optid MY_ATTRIBUTE((unused)),
                              const struct my_option *opt,
                              char *argument)
{
  return 0;
}


/**
  Creates a set of my_option objects associated with a specified plugin-
  handle.

  @param mem_root Memory allocator to be used.
  @param tmp A pointer to a plugin handle
  @param[out] options A pointer to a pre-allocated static array

  The set is stored in the pre-allocated static array supplied to the function.
  The size of the array is calculated as (number_of_plugin_varaibles*2+3). The
  reason is that each option can have a prefix '--plugin-' in addtion to the
  shorter form '--&lt;plugin-name&gt;'. There is also space allocated for
  terminating NULL pointers.

  @return
    @retval -1 An error occurred
    @retval 0 Success
*/

static int construct_options(MEM_ROOT *mem_root, st_plugin_int *tmp,
                             my_option *options)
{
  const char *plugin_name= tmp->plugin->name;
  const LEX_STRING plugin_dash = { C_STRING_WITH_LEN("plugin-") };
  size_t plugin_name_len= strlen(plugin_name);
  size_t optnamelen;
  const int max_comment_len= 180;
  char *comment= (char *) alloc_root(mem_root, max_comment_len + 1);
  char *optname;

  int index= 0, offset= 0;
  st_mysql_sys_var *opt, **plugin_option;
  st_bookmark *v;

  /** Used to circumvent the const attribute on my_option::name */
  char *plugin_name_ptr, *plugin_name_with_prefix_ptr;

  DBUG_ENTER("construct_options");

  plugin_name_ptr= (char*) alloc_root(mem_root, plugin_name_len + 1);
  strcpy(plugin_name_ptr, plugin_name);
  my_casedn_str(&my_charset_latin1, plugin_name_ptr);
  convert_underscore_to_dash(plugin_name_ptr, plugin_name_len);
  plugin_name_with_prefix_ptr= (char*) alloc_root(mem_root,
                                                  plugin_name_len +
                                                  plugin_dash.length + 1);
  strxmov(plugin_name_with_prefix_ptr, plugin_dash.str, plugin_name_ptr, NullS);

  if (tmp->load_option != PLUGIN_FORCE &&
      tmp->load_option != PLUGIN_FORCE_PLUS_PERMANENT)
  {
    /* support --skip-plugin-foo syntax */
    options[0].name= plugin_name_ptr;
    options[1].name= plugin_name_with_prefix_ptr;
    options[0].id= 0;
    options[1].id= -1;
    options[0].var_type= options[1].var_type= GET_ENUM;
    options[0].arg_type= options[1].arg_type= OPT_ARG;
    options[0].def_value= options[1].def_value= 1; /* ON */
    options[0].typelib= options[1].typelib= &global_plugin_typelib;

    strxnmov(comment, max_comment_len, "Enable or disable ", plugin_name,
            " plugin. Possible values are ON, OFF, FORCE (don't start "
            "if the plugin fails to load).", NullS);
    options[0].comment= comment;
    /*
      Allocate temporary space for the value of the tristate.
      This option will have a limited lifetime and is not used beyond
      server initialization.
      GET_ENUM value is an unsigned long integer.
    */
    options[0].value= options[1].value=
                      (uchar **)alloc_root(mem_root, sizeof(ulong));
    *((ulong*) options[0].value)= (ulong) options[0].def_value;

    options+= 2;
  }

  if (!my_strcasecmp(&my_charset_latin1, plugin_name_ptr, "NDBCLUSTER"))
  {
    plugin_name_ptr= const_cast<char*>("ndb"); // Use legacy "ndb" prefix
    plugin_name_len= 3;
  }

  /*
    Two passes as the 2nd pass will take pointer addresses for use
    by my_getopt and register_var() in the first pass uses realloc
  */

  for (plugin_option= tmp->plugin->system_vars;
       plugin_option && *plugin_option; plugin_option++, index++)
  {
    opt= *plugin_option;
    if (!(opt->flags & PLUGIN_VAR_THDLOCAL))
      continue;
    if (!(register_var(plugin_name_ptr, opt->name, opt->flags)))
      continue;
    switch (opt->flags & PLUGIN_VAR_TYPEMASK) {
    case PLUGIN_VAR_BOOL:
      ((thdvar_bool_t *) opt)->resolve= mysql_sys_var_char;
      break;
    case PLUGIN_VAR_INT:
      ((thdvar_int_t *) opt)->resolve= mysql_sys_var_int;
      break;
    case PLUGIN_VAR_LONG:
      ((thdvar_long_t *) opt)->resolve= mysql_sys_var_long;
      break;
    case PLUGIN_VAR_LONGLONG:
      ((thdvar_longlong_t *) opt)->resolve= mysql_sys_var_longlong;
      break;
    case PLUGIN_VAR_STR:
      ((thdvar_str_t *) opt)->resolve= mysql_sys_var_str;
      break;
    case PLUGIN_VAR_ENUM:
      ((thdvar_enum_t *) opt)->resolve= mysql_sys_var_ulong;
      break;
    case PLUGIN_VAR_SET:
      ((thdvar_set_t *) opt)->resolve= mysql_sys_var_ulonglong;
      break;
    case PLUGIN_VAR_DOUBLE:
      ((thdvar_double_t *) opt)->resolve= mysql_sys_var_double;
      break;
    default:
      sql_print_error("Unknown variable type code 0x%x in plugin '%s'.",
                      opt->flags, plugin_name);
      DBUG_RETURN(-1);
    };
  }

  for (plugin_option= tmp->plugin->system_vars;
       plugin_option && *plugin_option; plugin_option++, index++)
  {
    switch ((opt= *plugin_option)->flags & PLUGIN_VAR_TYPEMASK) {
    case PLUGIN_VAR_BOOL:
      if (!opt->check)
        opt->check= check_func_bool;
      if (!opt->update)
        opt->update= update_func_bool;
      break;
    case PLUGIN_VAR_INT:
      if (!opt->check)
        opt->check= check_func_int;
      if (!opt->update)
        opt->update= update_func_int;
      break;
    case PLUGIN_VAR_LONG:
      if (!opt->check)
        opt->check= check_func_long;
      if (!opt->update)
        opt->update= update_func_long;
      break;
    case PLUGIN_VAR_LONGLONG:
      if (!opt->check)
        opt->check= check_func_longlong;
      if (!opt->update)
        opt->update= update_func_longlong;
      break;
    case PLUGIN_VAR_STR:
      if (!opt->check)
        opt->check= check_func_str;
      if (!opt->update)
      {
        opt->update= update_func_str;
        if (!(opt->flags & (PLUGIN_VAR_MEMALLOC | PLUGIN_VAR_READONLY)))
        {
          opt->flags|= PLUGIN_VAR_READONLY;
          sql_print_warning("Server variable %s of plugin %s was forced "
                            "to be read-only: string variable without "
                            "update_func and PLUGIN_VAR_MEMALLOC flag",
                            opt->name, plugin_name);
        }
      }
      break;
    case PLUGIN_VAR_ENUM:
      if (!opt->check)
        opt->check= check_func_enum;
      if (!opt->update)
        opt->update= update_func_long;
      break;
    case PLUGIN_VAR_SET:
      if (!opt->check)
        opt->check= check_func_set;
      if (!opt->update)
        opt->update= update_func_longlong;
      break;
    case PLUGIN_VAR_DOUBLE:
      if (!opt->check)
        opt->check= check_func_double;
      if (!opt->update)
        opt->update= update_func_double;
      break;
    default:
      sql_print_error("Unknown variable type code 0x%x in plugin '%s'.",
                      opt->flags, plugin_name);
      DBUG_RETURN(-1);
    }

    if ((opt->flags & (PLUGIN_VAR_NOCMDOPT | PLUGIN_VAR_THDLOCAL))
                    == PLUGIN_VAR_NOCMDOPT)
      continue;

    if (!opt->name)
    {
      sql_print_error("Missing variable name in plugin '%s'.",
                      plugin_name);
      DBUG_RETURN(-1);
    }

    if (!(opt->flags & PLUGIN_VAR_THDLOCAL))
    {
      optnamelen= strlen(opt->name);
      optname= (char*) alloc_root(mem_root, plugin_name_len + optnamelen + 2);
      strxmov(optname, plugin_name_ptr, "-", opt->name, NullS);
      optnamelen= plugin_name_len + optnamelen + 1;
    }
    else
    {
      /* this should not fail because register_var should create entry */
      if (!(v= find_bookmark(plugin_name_ptr, opt->name, opt->flags)))
      {
        sql_print_error("Thread local variable '%s' not allocated "
                        "in plugin '%s'.", opt->name, plugin_name);
        DBUG_RETURN(-1);
      }

      *(int*)(opt + 1)= offset= v->offset;

      if (opt->flags & PLUGIN_VAR_NOCMDOPT)
        continue;

      optname= (char*) memdup_root(mem_root, v->key + 1,
                                   (optnamelen= v->name_len) + 1);
    }

    convert_underscore_to_dash(optname, optnamelen);

    options->name= optname;
    options->comment= opt->comment;
    options->app_type= opt;
    options->id= 0;

    plugin_opt_set_limits(options, opt);

    if (opt->flags & PLUGIN_VAR_THDLOCAL)
      options->value= options->u_max_value= (uchar**)
        (global_system_variables.dynamic_variables_ptr + offset);
    else
      options->value= options->u_max_value= *(uchar***) (opt + 1);

    char *option_name_ptr;
    options[1]= options[0];
    options[1].id= -1;
    options[1].name= option_name_ptr= (char*) alloc_root(mem_root,
                                                        plugin_dash.length +
                                                        optnamelen + 1);
    options[1].comment= 0; /* Hidden from the help text */
    strxmov(option_name_ptr, plugin_dash.str, optname, NullS);

    options+= 2;
  }

  DBUG_RETURN(0);
}


static my_option *construct_help_options(MEM_ROOT *mem_root,
                                         st_plugin_int *p)
{
  st_mysql_sys_var **opt;
  my_option *opts;
  uint count= EXTRA_OPTIONS;
  DBUG_ENTER("construct_help_options");

  for (opt= p->plugin->system_vars; opt && *opt; opt++, count+= 2)
    ;

  if (!(opts= (my_option*) alloc_root(mem_root, sizeof(my_option) * count)))
    DBUG_RETURN(NULL);

  memset(opts, 0, sizeof(my_option) * count);

  /**
    some plugin variables (those that don't have PLUGIN_VAR_NOSYSVAR flag)
    have their names prefixed with the plugin name. Restore the names here
    to get the correct (not double-prefixed) help text.
    We won't need @@sysvars anymore and don't care about their proper names.
  */
  restore_pluginvar_names(p->system_vars);

  if (construct_options(mem_root, p, opts))
    DBUG_RETURN(NULL);

  DBUG_RETURN(opts);
}


/**
  Check option being used and raise deprecation warning if required.

  @param optid ID of the option that was passed through command line
  @param opt List of options
  @argument Status of the option : Enable or Disable

  A deprecation warning will be raised if --plugin-xxx type of option
  is used.

  @return Always returns success as purpose of the function is to raise
  warning only.
  @retval 0 Success
*/

static my_bool check_if_option_is_deprecated(int optid,
                                             const struct my_option *opt,
                                             char *argument MY_ATTRIBUTE((unused)))
{
  if (optid == -1)
  {
    push_deprecated_warn(NULL, opt->name, (opt->name + strlen("plugin-")));
  }
  return 0;
}


/**
  Create and register system variables supplied from the plugin and
  assigns initial values from corresponding command line arguments.

  @param tmp_root Temporary scratch space
  @param[out] plugin Internal plugin structure
  @param argc Number of command line arguments
  @param argv Command line argument vector

  The plugin will be updated with a policy on how to handle errors during
  initialization.

  @note Requires that a write-lock is held on LOCK_system_variables_hash

  @return How initialization of the plugin should be handled.
    @retval  0 Initialization should proceed.
    @retval  1 Plugin is disabled.
    @retval -1 An error has occurred.
*/

static int test_plugin_options(MEM_ROOT *tmp_root, st_plugin_int *tmp,
                               int *argc, char **argv)
{
  struct sys_var_chain chain= { NULL, NULL };
  bool disable_plugin;
  enum_plugin_load_option plugin_load_option= tmp->load_option;

  MEM_ROOT *mem_root= alloc_root_inited(&tmp->mem_root) ?
                      &tmp->mem_root : &plugin_mem_root;
  st_mysql_sys_var **opt;
  my_option *opts= NULL;
  LEX_STRING plugin_name;
  char *varname;
  int error;
  sys_var *v MY_ATTRIBUTE((unused));
  st_bookmark *var;
  size_t len;
  uint count= EXTRA_OPTIONS;
  DBUG_ENTER("test_plugin_options");
  DBUG_ASSERT(tmp->plugin && tmp->name.str);

  /*
    The 'federated' and 'ndbcluster' storage engines are always disabled by
    default.
  */
  if (!(my_strcasecmp(&my_charset_latin1, tmp->name.str, "federated") &&
      my_strcasecmp(&my_charset_latin1, tmp->name.str, "ndbcluster")))
    plugin_load_option= PLUGIN_OFF;

  for (opt= tmp->plugin->system_vars; opt && *opt; opt++)
    count+= 2; /* --{plugin}-{optname} and --plugin-{plugin}-{optname} */

  if (count > EXTRA_OPTIONS || (*argc > 1))
  {
    if (!(opts= (my_option*) alloc_root(tmp_root, sizeof(my_option) * count)))
    {
      sql_print_error("Out of memory for plugin '%s'.", tmp->name.str);
      DBUG_RETURN(-1);
    }
    memset(opts, 0, sizeof(my_option) * count);

    if (construct_options(tmp_root, tmp, opts))
    {
      sql_print_error("Bad options for plugin '%s'.", tmp->name.str);
      DBUG_RETURN(-1);
    }

    /*
      We adjust the default value to account for the hardcoded exceptions
      we have set for the federated and ndbcluster storage engines.
    */
    if (tmp->load_option != PLUGIN_FORCE &&
        tmp->load_option != PLUGIN_FORCE_PLUS_PERMANENT)
      opts[0].def_value= opts[1].def_value= plugin_load_option;

    error= handle_options(argc, &argv, opts, check_if_option_is_deprecated);
    (*argc)++; /* add back one for the program name */

    if (error)
    {
       sql_print_error("Parsing options for plugin '%s' failed.",
                       tmp->name.str);
       goto err;
    }
    /*
     Set plugin loading policy from option value. First element in the option
     list is always the <plugin name> option value.
    */
    if (tmp->load_option != PLUGIN_FORCE &&
        tmp->load_option != PLUGIN_FORCE_PLUS_PERMANENT)
      plugin_load_option= (enum_plugin_load_option) *(ulong*) opts[0].value;
  }

  disable_plugin= (plugin_load_option == PLUGIN_OFF);
  tmp->load_option= plugin_load_option;

  /*
    If the plugin is disabled it should not be initialized.
  */
  if (disable_plugin)
  {
    sql_print_information("Plugin '%s' is disabled.",
                          tmp->name.str);
    if (opts)
      my_cleanup_options(opts);
    DBUG_RETURN(1);
  }

  if (!my_strcasecmp(&my_charset_latin1, tmp->name.str, "NDBCLUSTER"))
  {
    plugin_name.str= const_cast<char*>("ndb"); // Use legacy "ndb" prefix
    plugin_name.length= 3;
  }
  else
    plugin_name= tmp->name;

  error= 1;
  for (opt= tmp->plugin->system_vars; opt && *opt; opt++)
  {
    st_mysql_sys_var *o;
    if (((o= *opt)->flags & PLUGIN_VAR_NOSYSVAR))
      continue;
    if ((var= find_bookmark(plugin_name.str, o->name, o->flags)))
      v= new (mem_root) sys_var_pluginvar(&chain, var->key + 1, o);
    else
    {
      len= plugin_name.length + strlen(o->name) + 2;
      varname= (char*) alloc_root(mem_root, len);
      strxmov(varname, plugin_name.str, "-", o->name, NullS);
      my_casedn_str(&my_charset_latin1, varname);
      convert_dash_to_underscore(varname, len-1);
      v= new (mem_root) sys_var_pluginvar(&chain, varname, o);
    }
    DBUG_ASSERT(v); /* check that an object was actually constructed */
  } /* end for */
  if (chain.first)
  {
    chain.last->next = NULL;
    if (mysql_add_sys_var_chain(chain.first))
    {
      sql_print_error("Plugin '%s' has conflicting system variables",
                      tmp->name.str);
      goto err;
    }
    tmp->system_vars= chain.first;
  }
  DBUG_RETURN(0);

err:
  if (opts)
    my_cleanup_options(opts);
  DBUG_RETURN(error);
}


/****************************************************************************
  Help Verbose text with Plugin System Variables
****************************************************************************/


void add_plugin_options(std::vector<my_option> *options, MEM_ROOT *mem_root)
{
  my_option *opt;

  if (!initialized)
    return;

  for (st_plugin_int **it= plugin_array->begin();
       it != plugin_array->end(); ++it)
  {
    st_plugin_int *p= *it;

    if (!(opt= construct_help_options(mem_root, p)))
      continue;

    /* Only options with a non-NULL comment are displayed in help text */
    for (;opt->name; opt++)
      if (opt->comment)
        options->push_back(*opt);
  }
}

/**
  Searches for a correctly loaded plugin of a particular type by name

  @param plugin   the name of the plugin we're looking for
  @param type     type of the plugin (0-MYSQL_MAX_PLUGIN_TYPE_NUM)
  @return plugin, or NULL if not found
*/
st_plugin_int *plugin_find_by_type(const LEX_CSTRING &plugin, int type)
{
  st_plugin_int *ret;
  DBUG_ENTER("plugin_find_by_type");

  ret= plugin_find_internal(plugin, type);
  DBUG_RETURN(ret && ret->state == PLUGIN_IS_READY ? ret : NULL);
}


/**
  Locks the plugin strucutres so calls to plugin_find_inner can be issued.

  Must be followed by unlock_plugin_data.
*/
int lock_plugin_data()
{
  DBUG_ENTER("lock_plugin_data");
  DBUG_RETURN(mysql_mutex_lock(&LOCK_plugin));
}


/**
  Unlocks the plugin strucutres as locked by lock_plugin_data()
*/
int unlock_plugin_data()
{
  DBUG_ENTER("unlock_plugin_data");
  DBUG_RETURN(mysql_mutex_unlock(&LOCK_plugin));
}


bool Sql_cmd_install_plugin::execute(THD *thd)
{
  bool st= mysql_install_plugin(thd, &m_comment, &m_ident);
  if (!st)
    my_ok(thd);
#ifndef EMBEDDED_LIBRARY
  mysql_audit_release(thd);
#endif
  return st;
}


bool Sql_cmd_uninstall_plugin::execute(THD *thd)
{
  bool st= mysql_uninstall_plugin(thd, &m_comment);
  if (!st)
    my_ok(thd);
  return st;
}