/* Copyright (c) 2010, 2021, Oracle and/or its affiliates.

   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, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#include "datadict.h"
#include "sql_class.h"
#include "sql_table.h"

#include "pfs_file_provider.h"
#include "mysql/psi/mysql_file.h"

/**
  Check type of .frm if we are not going to parse it.

  @param[in]  thd   The current session.
  @param[in]  path  path to FRM file.
  @param[out] dbt   db_type of the table if FRMTYPE_TABLE, otherwise undefined.

  @retval  FRMTYPE_ERROR        error
  @retval  FRMTYPE_TABLE        table
  @retval  FRMTYPE_VIEW         view
*/

frm_type_enum dd_frm_type(THD *thd, char *path, enum legacy_db_type *dbt)
{
  File file;
  uchar header[10];     //"TYPE=VIEW\n" it is 10 characters
  size_t error;
  DBUG_ENTER("dd_frm_type");

  *dbt= DB_TYPE_UNKNOWN;

  if ((file= mysql_file_open(key_file_frm, path, O_RDONLY | O_SHARE, MYF(0))) < 0)
    DBUG_RETURN(FRMTYPE_ERROR);
  error= mysql_file_read(file, (uchar*) header, sizeof(header), MYF(MY_NABP));
  mysql_file_close(file, MYF(MY_WME));

  if (error)
    DBUG_RETURN(FRMTYPE_ERROR);
  if (!strncmp((char*) header, "TYPE=VIEW\n", sizeof(header)))
    DBUG_RETURN(FRMTYPE_VIEW);

  /*
    This is just a check for DB_TYPE. We'll return default unknown type
    if the following test is true (arg #3). This should not have effect
    on return value from this function (default FRMTYPE_TABLE)
  */
  if (header[0] != (uchar) 254 || header[1] != 1 ||
      (header[2] != FRM_VER && header[2] != FRM_VER+1 &&
       (header[2] < FRM_VER+3 || header[2] > FRM_VER+4)))
    DBUG_RETURN(FRMTYPE_TABLE);

  *dbt= (enum legacy_db_type) (uint) *(header + 3);

  /* Probably a table. */
  DBUG_RETURN(FRMTYPE_TABLE);
}


/**
  Given a table name, check type of .frm and legacy table type.

  @param[in]   thd          The current session.
  @param[in]   db           Table schema.
  @param[in]   table_name   Table database.
  @param[out]  table_type   handlerton of the table if FRMTYPE_TABLE,
                            otherwise undefined.

  @return FALSE if FRMTYPE_TABLE and storage engine found. TRUE otherwise.
*/

bool dd_frm_storage_engine(THD *thd, const char *db, const char *table_name,
                           handlerton **table_type)
{
  char path[FN_REFLEN + 1];
  enum legacy_db_type db_type;
  LEX_STRING db_name = {(char *) db, strlen(db)};

  /* There should be at least some lock on the table.  */
  assert(thd->mdl_context.owns_equal_or_stronger_lock(MDL_key::TABLE,
                                                      db, table_name,
                                                      MDL_SHARED));

  if (check_and_convert_db_name(&db_name, FALSE) != IDENT_NAME_OK)
    return TRUE;

  enum_ident_name_check ident_check_status=
    check_table_name(table_name, strlen(table_name), FALSE);
  if (ident_check_status == IDENT_NAME_WRONG)
  {
    my_error(ER_WRONG_TABLE_NAME, MYF(0), table_name);
    return TRUE;
  }
  else if (ident_check_status == IDENT_NAME_TOO_LONG)
  {
    my_error(ER_TOO_LONG_IDENT, MYF(0), table_name);
    return TRUE;
  }

  (void) build_table_filename(path, sizeof(path) - 1, db,
                              table_name, reg_ext, 0);

  dd_frm_type(thd, path, &db_type);

  /* Type is unknown if the object is not found or is not a table. */
  if (db_type == DB_TYPE_UNKNOWN)
  {
    my_error(ER_NO_SUCH_TABLE, MYF(0), db, table_name);
    return TRUE;
  }
  else if (!(*table_type= ha_resolve_by_legacy_type(thd, db_type)))
  {
    my_error(ER_STORAGE_ENGINE_NOT_LOADED, MYF(0), db, table_name);
    return TRUE;
  }

  return FALSE;
}


/**
  Given a table name, check if the storage engine for the
  table referred by this name supports an option 'flag'.
  Return an error if the table does not exist or is not a
  base table.

  @pre Any metadata lock on the table.

  @param[in]    thd         The current session.
  @param[in]    db          Table schema.
  @param[in]    table_name  Table database.
  @param[in]    flag        The option to check.
  @param[out]   yes_no      The result. Undefined if error.
*/

bool dd_check_storage_engine_flag(THD *thd,
                                  const char *db, const char *table_name,
                                  uint32 flag, bool *yes_no)
{
  handlerton *table_type;

  if (dd_frm_storage_engine(thd, db, table_name, &table_type))
    return TRUE;

  *yes_no= ha_check_storage_engine_flag(table_type, flag);

  return FALSE;
}


/*
  Regenerate a metadata locked table.

  @param  thd   Thread context.
  @param  db    Name of the database to which the table belongs to.
  @param  name  Table name.

  @retval  FALSE  Success.
  @retval  TRUE   Error.
*/

bool dd_recreate_table(THD *thd, const char *db, const char *table_name)
{
  bool error= TRUE;
  HA_CREATE_INFO create_info;
  char path[FN_REFLEN + 1];
  DBUG_ENTER("dd_recreate_table");

  /* There should be a exclusive metadata lock on the table. */
  assert(thd->mdl_context.owns_equal_or_stronger_lock(MDL_key::TABLE,
                                                      db, table_name,
                                                      MDL_EXCLUSIVE));

  /* Create a path to the table, but without a extension. */
  build_table_filename(path, sizeof(path) - 1, db, table_name, "", 0);

  /* Attempt to reconstruct the table. */
  error= ha_create_table(thd, path, db, table_name, &create_info, TRUE);

  DBUG_RETURN(error);
}

