path: root/sql/sql_plugin.cc

/* Copyright (C) 2005 MySQL AB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   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 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, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#include "mysql_priv.h"
#include <my_pthread.h>
#define REPORT_TO_LOG  1
#define REPORT_TO_USER 2

extern struct st_mysql_plugin *mysqld_builtins[];

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") }
};

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

/*
  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
};

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

#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

/* 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
};
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
};

static DYNAMIC_ARRAY plugin_dl_array;
static DYNAMIC_ARRAY plugin_array;
static HASH plugin_hash[MYSQL_MAX_PLUGIN_TYPE_NUM];
static rw_lock_t THR_LOCK_plugin;
static bool initialized= 0;

static int plugin_array_version=0;

/* prototypes */
my_bool plugin_register_builtin(struct st_mysql_plugin *plugin);
void plugin_load(void);

#ifdef HAVE_DLOPEN

static struct st_plugin_dl *plugin_dl_find(const LEX_STRING *dl)
{
  uint i;
  DBUG_ENTER("plugin_dl_find");
  for (i= 0; i < plugin_dl_array.elements; i++)
  {
    struct st_plugin_dl *tmp= dynamic_element(&plugin_dl_array, i,
                                              struct st_plugin_dl *);
    if (tmp->ref_count &&
        ! my_strnncoll(files_charset_info,
                       (const uchar *)dl->str, dl->length,
                       (const uchar *)tmp->dl.str, tmp->dl.length))
      DBUG_RETURN(tmp);
  }
  DBUG_RETURN(0);
}


static st_plugin_dl *plugin_dl_insert_or_reuse(struct st_plugin_dl *plugin_dl)
{
  uint i;
  DBUG_ENTER("plugin_dl_insert_or_reuse");
  for (i= 0; i < plugin_dl_array.elements; i++)
  {
    struct st_plugin_dl *tmp= dynamic_element(&plugin_dl_array, i,
                                              struct st_plugin_dl *);
    if (! tmp->ref_count)
    {
      memcpy(tmp, plugin_dl, sizeof(struct st_plugin_dl));
      DBUG_RETURN(tmp);
    }
  }
  if (insert_dynamic(&plugin_dl_array, (gptr)plugin_dl))
    DBUG_RETURN(0);
  DBUG_RETURN(dynamic_element(&plugin_dl_array, plugin_dl_array.elements - 1,
                              struct st_plugin_dl *));
}
#endif /* HAVE_DLOPEN */


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

static st_plugin_dl *plugin_dl_add(const LEX_STRING *dl, int report)
{
#ifdef HAVE_DLOPEN
  char dlpath[FN_REFLEN];
  uint plugin_dir_len, dummy_errors, dlpathlen;
  struct st_plugin_dl *tmp, plugin_dl;
  void *sym;
  DBUG_ENTER("plugin_dl_add");
  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).
  */
  if (my_strchr(files_charset_info, dl->str, dl->str + dl->length, FN_LIBCHAR) ||
      check_string_char_length((LEX_STRING *) dl, "", NAME_CHAR_LEN,
                               system_charset_info, 1) ||
      plugin_dir_len + dl->length + 1 >= FN_REFLEN)
  {
    if (report & REPORT_TO_USER)
      my_error(ER_UDF_NO_PATHS, MYF(0));
    if (report & REPORT_TO_LOG)
      sql_print_error(ER(ER_UDF_NO_PATHS));
    DBUG_RETURN(0);
  }
  /* If this dll is already loaded just increase ref_count. */
  if ((tmp= plugin_dl_find(dl)))
  {
    tmp->ref_count++;
    DBUG_RETURN(tmp);
  }
  bzero(&plugin_dl, sizeof(plugin_dl));
  /* Compile dll path */
  dlpathlen=
    strxnmov(dlpath, sizeof(dlpath) - 1, opt_plugin_dir, "/", dl->str, NullS) -
    dlpath;
  plugin_dl.ref_count= 1;
  /* Open new dll handle */
  if (!(plugin_dl.handle= dlopen(dlpath, RTLD_NOW)))
  {
    const char *errmsg=dlerror();
    if (!strncmp(dlpath, errmsg, dlpathlen))
    { // if errmsg starts from dlpath, trim this prefix.
      errmsg+=dlpathlen;
      if (*errmsg == ':') errmsg++;
      if (*errmsg == ' ') errmsg++;
    }
    if (report & REPORT_TO_USER)
      my_error(ER_CANT_OPEN_LIBRARY, MYF(0), dlpath, errno, errmsg);
    if (report & REPORT_TO_LOG)
      sql_print_error(ER(ER_CANT_OPEN_LIBRARY), dlpath, errno, errmsg);
    DBUG_RETURN(0);
  }
  /* Determine interface version */
  if (!(sym= dlsym(plugin_dl.handle, plugin_interface_version_sym)))
  {
    free_plugin_mem(&plugin_dl);
    if (report & REPORT_TO_USER)
      my_error(ER_CANT_FIND_DL_ENTRY, MYF(0), plugin_interface_version_sym);
    if (report & REPORT_TO_LOG)
      sql_print_error(ER(ER_CANT_FIND_DL_ENTRY), plugin_interface_version_sym);
    DBUG_RETURN(0);
  }
  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);
    if (report & REPORT_TO_USER)
      my_error(ER_CANT_OPEN_LIBRARY, MYF(0), dlpath, 0,
               "plugin interface version mismatch");
    if (report & REPORT_TO_LOG)
      sql_print_error(ER(ER_CANT_OPEN_LIBRARY), dlpath, 0,
                      "plugin interface version mismatch");
    DBUG_RETURN(0);
  }
  /* Find plugin declarations */
  if (!(sym= dlsym(plugin_dl.handle, plugin_declarations_sym)))
  {
    free_plugin_mem(&plugin_dl);
    if (report & REPORT_TO_USER)
      my_error(ER_CANT_FIND_DL_ENTRY, MYF(0), plugin_declarations_sym);
    if (report & REPORT_TO_LOG)
      sql_print_error(ER(ER_CANT_FIND_DL_ENTRY), plugin_declarations_sym);
    DBUG_RETURN(0);
  }

  if (plugin_dl.version != MYSQL_PLUGIN_INTERFACE_VERSION)
  {
    int i;
    uint sizeof_st_plugin;
    struct 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
    {
#ifdef ERROR_ON_NO_SIZEOF_PLUGIN_SYMBOL
      free_plugin_mem(&plugin_dl);
      if (report & REPORT_TO_USER)
        my_error(ER_CANT_FIND_DL_ENTRY, MYF(0), sizeof_st_plugin_sym);
      if (report & REPORT_TO_LOG)
        sql_print_error(ER(ER_CANT_FIND_DL_ENTRY), sizeof_st_plugin_sym);
      DBUG_RETURN(0);
#else
      /*
        When the following assert starts failing, we'll have to switch
        to the upper branch of the #ifdef
      */
      DBUG_ASSERT(min_plugin_interface_version == 0);
      sizeof_st_plugin= (int)offsetof(struct st_mysql_plugin, version);
#endif
    }

    for (i= 0;
         ((struct st_mysql_plugin *)(ptr+i*sizeof_st_plugin))->info;
         i++)
      /* no op */;

    cur= (struct st_mysql_plugin*)
          my_malloc(i*sizeof(struct st_mysql_plugin), MYF(MY_ZEROFILL|MY_WME));
    if (!cur)
    {
      free_plugin_mem(&plugin_dl);
      if (report & REPORT_TO_USER)
        my_error(ER_OUTOFMEMORY, MYF(0), plugin_dl.dl.length);
      if (report & REPORT_TO_LOG)
        sql_print_error(ER(ER_OUTOFMEMORY), plugin_dl.dl.length);
      DBUG_RETURN(0);
    }
    /*
      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=(struct st_mysql_plugin *)(ptr+i*sizeof_st_plugin))->info;
         i++)
      memcpy(cur+i, old, min(sizeof(cur[i]), sizeof_st_plugin));

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

  /* Duplicate and convert dll name */
  plugin_dl.dl.length= dl->length * files_charset_info->mbmaxlen + 1;
  if (! (plugin_dl.dl.str= my_malloc(plugin_dl.dl.length, MYF(0))))
  {
    free_plugin_mem(&plugin_dl);
    if (report & REPORT_TO_USER)
      my_error(ER_OUTOFMEMORY, MYF(0), plugin_dl.dl.length);
    if (report & REPORT_TO_LOG)
      sql_print_error(ER(ER_OUTOFMEMORY), plugin_dl.dl.length);
    DBUG_RETURN(0);
  }
  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)))
  {
    free_plugin_mem(&plugin_dl);
    if (report & REPORT_TO_USER)
      my_error(ER_OUTOFMEMORY, MYF(0), sizeof(struct st_plugin_dl));
    if (report & REPORT_TO_LOG)
      sql_print_error(ER(ER_OUTOFMEMORY), sizeof(struct st_plugin_dl));
    DBUG_RETURN(0);
  }
  DBUG_RETURN(tmp);
#else
  DBUG_ENTER("plugin_dl_add");
  if (report & REPORT_TO_USER)
    my_error(ER_FEATURE_DISABLED, MYF(0), "plugin", "HAVE_DLOPEN");
  if (report & REPORT_TO_LOG)
    sql_print_error(ER(ER_FEATURE_DISABLED), "plugin", "HAVE_DLOPEN");
  DBUG_RETURN(0);
#endif
}


static void plugin_dl_del(const LEX_STRING *dl)
{
#ifdef HAVE_DLOPEN
  uint i;
  DBUG_ENTER("plugin_dl_del");
  for (i= 0; i < plugin_dl_array.elements; i++)
  {
    struct st_plugin_dl *tmp= dynamic_element(&plugin_dl_array, i,
                                              struct st_plugin_dl *);
    if (tmp->ref_count &&
        ! my_strnncoll(files_charset_info,
                       (const uchar *)dl->str, dl->length,
                       (const 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);
        bzero(tmp, sizeof(struct st_plugin_dl));
      }
      break;
    }
  }
  DBUG_VOID_RETURN;
#endif
}


static struct st_plugin_int *plugin_find_internal(const LEX_STRING *name, int type)
{
  uint i;
  DBUG_ENTER("plugin_find_internal");
  if (! initialized)
    DBUG_RETURN(0);
  if (type == MYSQL_ANY_PLUGIN)
  {
    for (i= 0; i < MYSQL_MAX_PLUGIN_TYPE_NUM; i++)
    {
      struct st_plugin_int *plugin= (st_plugin_int *)
        hash_search(&plugin_hash[i], (const byte *)name->str, name->length);
      if (plugin)
        DBUG_RETURN(plugin);
    }
  }
  else
    DBUG_RETURN((st_plugin_int *)
        hash_search(&plugin_hash[type], (const byte *)name->str, name->length));
  DBUG_RETURN(0);
}


my_bool plugin_is_ready(const LEX_STRING *name, int type)
{
  my_bool rc= FALSE;
  struct st_plugin_int *plugin;
  DBUG_ENTER("plugin_is_ready");
  rw_rdlock(&THR_LOCK_plugin);
  if ((plugin= plugin_find_internal(name, type)) &&
      plugin->state == PLUGIN_IS_READY)
    rc= TRUE;
  rw_unlock(&THR_LOCK_plugin);
  DBUG_RETURN(rc);
}


struct st_plugin_int *plugin_lock(const LEX_STRING *name, int type)
{
  struct st_plugin_int *rc;
  DBUG_ENTER("plugin_lock");
  rw_wrlock(&THR_LOCK_plugin);
  if ((rc= plugin_find_internal(name, type)))
  {
    if (rc->state & (PLUGIN_IS_READY | PLUGIN_IS_UNINITIALIZED))
      rc->ref_count++;
    else
      rc= 0;
  }
  rw_unlock(&THR_LOCK_plugin);
  DBUG_RETURN(rc);
}


static st_plugin_int *plugin_insert_or_reuse(struct st_plugin_int *plugin)
{
  uint i;
  DBUG_ENTER("plugin_insert_or_reuse");
  for (i= 0; i < plugin_array.elements; i++)
  {
    struct st_plugin_int *tmp= dynamic_element(&plugin_array, i,
                                               struct st_plugin_int *);
    if (tmp->state == PLUGIN_IS_FREED)
    {
      memcpy(tmp, plugin, sizeof(struct st_plugin_int));
      DBUG_RETURN(tmp);
    }
  }
  if (insert_dynamic(&plugin_array, (gptr)plugin))
    DBUG_RETURN(0);
  DBUG_RETURN(dynamic_element(&plugin_array, plugin_array.elements - 1,
                              struct st_plugin_int *));
}

static my_bool plugin_add(const LEX_STRING *name, const LEX_STRING *dl, int report)
{
  struct st_plugin_int tmp;
  struct st_mysql_plugin *plugin;
  DBUG_ENTER("plugin_add");
  if (plugin_find_internal(name, MYSQL_ANY_PLUGIN))
  {
    if (report & REPORT_TO_USER)
      my_error(ER_UDF_EXISTS, MYF(0), name->str);
    if (report & REPORT_TO_LOG)
      sql_print_error(ER(ER_UDF_EXISTS), name->str);
    DBUG_RETURN(TRUE);
  }
  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++)
  {
    uint name_len= strlen(plugin->name);
    if (plugin->type >= 0 && plugin->type < MYSQL_MAX_PLUGIN_TYPE_NUM &&
        ! my_strnncoll(system_charset_info,
                       (const uchar *)name->str, name->length,
                       (const uchar *)plugin->name,
                       name_len))
    {
      struct 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];
        strxnmov(buf, sizeof(buf) - 1, "API version for ",
                 plugin_type_names[plugin->type].str,
                 " plugin is too different", NullS);
        if (report & REPORT_TO_USER)
          my_error(ER_CANT_OPEN_LIBRARY, MYF(0), dl->str, 0, buf);
        if (report & REPORT_TO_LOG)
          sql_print_error(ER(ER_CANT_OPEN_LIBRARY), dl->str, 0, buf);
        goto err;
      }
      tmp.plugin= plugin;
      tmp.name.str= (char *)plugin->name;
      tmp.name.length= name_len;
      tmp.ref_count= 0;
      tmp.state= PLUGIN_IS_UNINITIALIZED;
      if (! (tmp_plugin_ptr= plugin_insert_or_reuse(&tmp)))
        goto err;
      plugin_array_version++;
      if (my_hash_insert(&plugin_hash[plugin->type], (byte*)tmp_plugin_ptr))
      {
        tmp_plugin_ptr->state= PLUGIN_IS_FREED;
        goto err;
      }
      DBUG_RETURN(FALSE);
    }
  }
  if (report & REPORT_TO_USER)
    my_error(ER_CANT_FIND_DL_ENTRY, MYF(0), name->str);
  if (report & REPORT_TO_LOG)
    sql_print_error(ER(ER_CANT_FIND_DL_ENTRY), name->str);
err:
  plugin_dl_del(dl);
  DBUG_RETURN(TRUE);
}


void plugin_deinitialize(struct st_plugin_int *plugin)
{

  if (plugin->plugin->status_vars)
  {
#ifdef FIX_LATER
    /*
      We have a problem right now where we can not prepend without
      breaking backwards compatibility. We will fix this shortly so
      that engines have "use names" and we wil use those for
      CREATE TABLE, and use the plugin name then for adding automatic
      variable names.
    */
    SHOW_VAR array[2]= {
      {plugin->plugin->name, (char*)plugin->plugin->status_vars, SHOW_ARRAY},
      {0, 0, SHOW_UNDEF}
    };
    remove_status_vars(array);
#else
    remove_status_vars(plugin->plugin->status_vars);
#endif /* FIX_LATER */
  }

  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;
}


static void plugin_del(struct st_plugin_int *plugin)
{
  DBUG_ENTER("plugin_del(plugin)");
  hash_delete(&plugin_hash[plugin->plugin->type], (byte*)plugin);
  plugin_dl_del(&plugin->plugin_dl->dl);
  plugin->state= PLUGIN_IS_FREED;
  plugin_array_version++;
  DBUG_VOID_RETURN;
}

#ifdef NOT_USED

static void plugin_del(const LEX_STRING *name)
{
  struct st_plugin_int *plugin;
  DBUG_ENTER("plugin_del(name)");
  if ((plugin= plugin_find_internal(name, MYSQL_ANY_PLUGIN)))
    plugin_del(plugin);
  DBUG_VOID_RETURN;
}

#endif

void plugin_unlock(struct st_plugin_int *plugin)
{
  DBUG_ENTER("plugin_unlock");
  rw_wrlock(&THR_LOCK_plugin);
  DBUG_ASSERT(plugin && plugin->ref_count);
  plugin->ref_count--;
  if (plugin->state == PLUGIN_IS_DELETED && ! plugin->ref_count)
  {
    plugin_deinitialize(plugin);
    plugin_del(plugin);
  }
  rw_unlock(&THR_LOCK_plugin);
  DBUG_VOID_RETURN;
}


static int plugin_initialize(struct st_plugin_int *plugin)
{
  DBUG_ENTER("plugin_initialize");

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

  plugin->state= PLUGIN_IS_READY;

  if (plugin->plugin->status_vars)
  {
#ifdef FIX_LATER
    /*
      We have a problem right now where we can not prepend without
      breaking backwards compatibility. We will fix this shortly so
      that engines have "use names" and we wil use those for
      CREATE TABLE, and use the plugin name then for adding automatic
      variable names.
    */
    SHOW_VAR array[2]= {
      {plugin->plugin->name, (char*)plugin->plugin->status_vars, SHOW_ARRAY},
      {0, 0, SHOW_UNDEF}
    };
    if (add_status_vars(array)) // add_status_vars makes a copy
      goto err;
#else
    add_status_vars(plugin->plugin->status_vars); // add_status_vars makes a copy
#endif /* FIX_LATER */
  }

  DBUG_RETURN(0);
err:
  DBUG_RETURN(1);
}

static byte *get_hash_key(const byte *buff, uint *length,
                   my_bool not_used __attribute__((unused)))
{
  struct st_plugin_int *plugin= (st_plugin_int *)buff;
  *length= (uint)plugin->name.length;
  return((byte *)plugin->name.str);
}


/*
  The logic is that we first load and initialize all compiled in plugins.
  From there we load up the dynamic types (assuming we have not been told to
  skip this part).

  Finally we inializie everything, aka the dynamic that have yet to initialize.
*/
int plugin_init(int skip_dynamic_loading)
{
  uint i;
  struct st_mysql_plugin **builtins;
  struct st_mysql_plugin *plugin;
  DBUG_ENTER("plugin_init");

  if (initialized)
    DBUG_RETURN(0);

  my_rwlock_init(&THR_LOCK_plugin, NULL);

  if (my_init_dynamic_array(&plugin_dl_array,
                            sizeof(struct st_plugin_dl),16,16) ||
      my_init_dynamic_array(&plugin_array,
                            sizeof(struct st_plugin_int),16,16))
    goto err;

  for (i= 0; i < MYSQL_MAX_PLUGIN_TYPE_NUM; i++)
  {
    if (hash_init(&plugin_hash[i], system_charset_info, 16, 0, 0,
                  get_hash_key, NULL, 0))
      goto err;
  }

  /*
    First we register builtin plugins
  */
  for (builtins= mysqld_builtins; *builtins; builtins++)
  {
    for (plugin= *builtins; plugin->info; plugin++)
    {
//      if (!(strcmp(plugin->name, "MyISAM")))
      {
        if (plugin_register_builtin(plugin))
          goto err;
        struct st_plugin_int *tmp= dynamic_element(&plugin_array,
                                                   plugin_array.elements-1,
                                                   struct st_plugin_int *);
        if (plugin_initialize(tmp))
          goto err;
      }
    }
  }

  /* Register all dynamic plugins */
  if (!skip_dynamic_loading)
    plugin_load();

  initialized= 1;

  /*
    Now we initialize all remaining plugins
  */
  for (i= 0; i < plugin_array.elements; i++)
  {
    struct st_plugin_int *tmp= dynamic_element(&plugin_array, i,
                                               struct st_plugin_int *);
    if (tmp->state == PLUGIN_IS_UNINITIALIZED)
    {
      if (plugin_initialize(tmp))
      {
        plugin_deinitialize(tmp);
        plugin_del(tmp);
      }
    }
  }

  DBUG_RETURN(0);

err:
  DBUG_RETURN(1);
}


my_bool plugin_register_builtin(struct st_mysql_plugin *plugin)
{
  struct st_plugin_int tmp;
  DBUG_ENTER("plugin_register_builtin");

  tmp.plugin= plugin;
  tmp.name.str= (char *)plugin->name;
  tmp.name.length= strlen(plugin->name);
  tmp.state= PLUGIN_IS_UNINITIALIZED;

  /* Cannot be unloaded */
  tmp.ref_count= 1;
  tmp.plugin_dl= 0;

  if (insert_dynamic(&plugin_array, (gptr)&tmp))
    DBUG_RETURN(1);

  if (my_hash_insert(&plugin_hash[plugin->type],
                     (byte*)dynamic_element(&plugin_array,
                                            plugin_array.elements - 1,
                                            struct st_plugin_int *)))
    DBUG_RETURN(1);

  DBUG_RETURN(0);
}


void plugin_load(void)
{
  TABLE_LIST tables;
  TABLE *table;
  READ_RECORD read_record_info;
  int error;
  MEM_ROOT mem;
  THD *new_thd;
  DBUG_ENTER("plugin_load");

  if (!(new_thd= new THD))
  {
    sql_print_error("Can't allocate memory for plugin structures");
    delete new_thd;
    DBUG_VOID_RETURN;
  }
  init_sql_alloc(&mem, 1024, 0);
  new_thd->thread_stack= (char*) &tables;
  new_thd->store_globals();
  new_thd->db= my_strdup("mysql", MYF(0));
  new_thd->db_length= 5;
  bzero((gptr)&tables, sizeof(tables));
  tables.alias= tables.table_name= (char*)"plugin";
  tables.lock_type= TL_READ;
  tables.db= new_thd->db;
  if (simple_open_n_lock_tables(new_thd, &tables))
  {
    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.");
    goto end;
  }
  table= tables.table;
  init_read_record(&read_record_info, new_thd, table, NULL, 1, 0);
  table->use_all_columns();
  while (!(error= read_record_info.read_record(&read_record_info)))
  {
    DBUG_PRINT("info", ("init plugin record"));
    String str_name, str_dl;
    get_field(&mem, table->field[0], &str_name);
    get_field(&mem, 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()};

    if (plugin_add(&name, &dl, REPORT_TO_LOG))
      sql_print_warning("Couldn't load plugin named '%s' with soname '%s'.",
                        str_name.c_ptr(), str_dl.c_ptr());
  }
  if (error > 0)
    sql_print_error(ER(ER_GET_ERRNO), my_errno);
  end_read_record(&read_record_info);
  new_thd->version--; // Force close to free memory
end:
  free_root(&mem, MYF(0));
  close_thread_tables(new_thd);
  delete new_thd;
  /* Remember that we don't have a THD */
  my_pthread_setspecific_ptr(THR_THD, 0);
  DBUG_VOID_RETURN;
}


void plugin_shutdown(void)
{
  uint i;
  DBUG_ENTER("plugin_shutdown");

  /*
    We loop through all plugins and call deinit() if they have one.
  */
  for (i= 0; i < plugin_array.elements; i++)
  {
    struct st_plugin_int *tmp= dynamic_element(&plugin_array, i,
                                               struct st_plugin_int *);
    plugin_deinitialize(tmp);

  }

  for (i= 0; i < MYSQL_MAX_PLUGIN_TYPE_NUM; i++)
    hash_free(&plugin_hash[i]);
  delete_dynamic(&plugin_array);
  for (i= 0; i < plugin_dl_array.elements; i++)
  {
    struct st_plugin_dl *tmp= dynamic_element(&plugin_dl_array, i,
                                              struct st_plugin_dl *);
    free_plugin_mem(tmp);
  }
  delete_dynamic(&plugin_dl_array);
  if (initialized)
  {
    initialized= 0;
    rwlock_destroy(&THR_LOCK_plugin);
  }
  DBUG_VOID_RETURN;
}


my_bool mysql_install_plugin(THD *thd, const LEX_STRING *name, const LEX_STRING *dl)
{
  TABLE_LIST tables;
  TABLE *table;
  int error;
  struct st_plugin_int *tmp;
  DBUG_ENTER("mysql_install_plugin");

  bzero(&tables, sizeof(tables));
  tables.db= (char *)"mysql";
  tables.table_name= tables.alias= (char *)"plugin";
  if (check_table_access(thd, INSERT_ACL, &tables, 0))
    DBUG_RETURN(TRUE);

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

  rw_wrlock(&THR_LOCK_plugin);
  if (plugin_add(name, dl, REPORT_TO_USER))
    goto err;
  tmp= plugin_find_internal(name, MYSQL_ANY_PLUGIN);

  if (plugin_initialize(tmp))
  {
    my_error(ER_CANT_INITIALIZE_UDF, MYF(0), name->str,
             "Plugin initialization function failed.");
    goto deinit;
  }

  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]);
  if (error)
  {
    table->file->print_error(error, MYF(0));
    goto deinit;
  }

  rw_unlock(&THR_LOCK_plugin);
  DBUG_RETURN(FALSE);
deinit:
  plugin_deinitialize(tmp);
  plugin_del(tmp);
err:
  rw_unlock(&THR_LOCK_plugin);
  DBUG_RETURN(TRUE);
}


my_bool mysql_uninstall_plugin(THD *thd, const LEX_STRING *name)
{
  TABLE *table;
  TABLE_LIST tables;
  struct st_plugin_int *plugin;
  DBUG_ENTER("mysql_uninstall_plugin");

  bzero(&tables, sizeof(tables));
  tables.db= (char *)"mysql";
  tables.table_name= tables.alias= (char *)"plugin";

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

  rw_wrlock(&THR_LOCK_plugin);
  if (!(plugin= plugin_find_internal(name, MYSQL_ANY_PLUGIN)))
  {
    my_error(ER_SP_DOES_NOT_EXIST, MYF(0), "PLUGIN", name->str);
    goto err;
  }
  if (!plugin->plugin_dl)
  {
    push_warning(thd, MYSQL_ERROR::WARN_LEVEL_WARN, 0,
                 "Built-in plugins cannot be deleted,.");
    my_error(ER_SP_DOES_NOT_EXIST, MYF(0), "PLUGIN", name->str);
    goto err;
  }

  if (plugin->ref_count)
  {
    push_warning(thd, MYSQL_ERROR::WARN_LEVEL_WARN, 0,
                 "Plugin is busy and will be uninstalled on shutdown");
    plugin->state= PLUGIN_IS_DELETED;
  }
  else
  {
    plugin_deinitialize(plugin);
    plugin_del(plugin);
  }

  table->use_all_columns();
  table->field[0]->store(name->str, name->length, system_charset_info);
  if (! table->file->index_read_idx(table->record[0], 0,
                                    (byte *)table->field[0]->ptr, HA_WHOLE_KEY,
                                    HA_READ_KEY_EXACT))
  {
    int error;
    if ((error= table->file->ha_delete_row(table->record[0])))
    {
      table->file->print_error(error, MYF(0));
      goto err;
    }
  }
  rw_unlock(&THR_LOCK_plugin);
  DBUG_RETURN(FALSE);
err:
  rw_unlock(&THR_LOCK_plugin);
  DBUG_RETURN(TRUE);
}

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

  state_mask= ~state_mask; // do it only once

  rw_rdlock(&THR_LOCK_plugin);
  total= type == MYSQL_ANY_PLUGIN ? plugin_array.elements 
                                  : 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=(struct st_plugin_int **)my_alloca(total*sizeof(*plugins));
  if (type == MYSQL_ANY_PLUGIN)
  {
    for (idx= 0; idx < total; idx++)
    {
      plugin= dynamic_element(&plugin_array, idx, struct st_plugin_int *);
      plugins[idx]= !(plugin->state & state_mask) ? plugin : NULL;
    }
  }
  else
  {
    HASH *hash= plugin_hash + type;
    for (idx= 0; idx < total; idx++)
    {
      plugin= (struct st_plugin_int *) hash_element(hash, idx);
      plugins[idx]= !(plugin->state & state_mask) ? plugin : NULL;
    }
  }
  rw_unlock(&THR_LOCK_plugin);

  for (idx= 0; idx < total; idx++)
  {
    if (unlikely(version != plugin_array_version))
    {
      rw_rdlock(&THR_LOCK_plugin);
      for (uint i=idx; i < total; i++)
        if (plugins[i] && plugins[i]->state & state_mask)
          plugins[i]=0;
      rw_unlock(&THR_LOCK_plugin);
    }
    plugin= plugins[idx];
    if (plugin && func(thd, plugin, arg))
        goto err;
  }

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