/*
   Copyright (c) 2015, 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 "ndb_find_files_list.h"

#include "sql_show.h"       // find_files()
#include "sql_class.h"      // THD::col_access


// Hides the usage of MEM_ROOT and List<> from the interface
struct Ndb_find_files_list_impl {
  // MEM_ROOT which holds the memory of file names and list links
  MEM_ROOT m_mem_root;

  // List of files and it's iterator
  List<LEX_STRING> m_files_list;
  List_iterator_fast<LEX_STRING> m_files_list_it;

  Ndb_find_files_list_impl()
  {
    // Initialize the MEM_ROOT which hold the file names
    // which the list pointers point at.
    init_alloc_root(PSI_NOT_INSTRUMENTED, &m_mem_root, 1024, 0);
  }

  ~Ndb_find_files_list_impl()
  {
    free_root(&m_mem_root, 0);
  }
};


Ndb_find_files_list::Ndb_find_files_list(class THD* thd) :
  m_thd(thd),
  m_impl(NULL)
{
}


Ndb_find_files_list::~Ndb_find_files_list()
{
  delete m_impl;
}


bool
Ndb_find_files_list::find_files_impl(const char *db,
                                     const char *path,
                                     bool dir)
{
  m_impl = new Ndb_find_files_list_impl();
  if (!m_impl)
  {
    return false;
  }

  /*
      The schema distribution participant has full permissions
      to drop or create any database. When determining if a database
      should be dropped on participating mysqld it will thus need
      full permissions also when listing the tables in the database.
      Such permission is controlled by the "magic" THD::col_access variable
      and need to be set high enough so that find_files() returns all
      files in the database(without checking any grants).

      Without full permission no tables would  be returned for databases
      which have special access rights(like performance_schema and
      information_schema). Those would thus appear empty and a faulty
      decision to drop them would be taken.

      Fix by setting the "magic" THD::col_access member in order to skip
      the access control check in find_files().
    */
  const ulong saved_col_access= m_thd->col_access;
  assert(sizeof(saved_col_access) == sizeof(m_thd->col_access));
  m_thd->col_access|= TABLE_ACLS;

  const find_files_result result = find_files(m_thd,
                                              &m_impl->m_files_list,
                                              db, path, NULL, dir,
                                              &m_impl->m_mem_root);
  if (result != FIND_FILES_OK)
  {
    // Restore column access rights
    m_thd->col_access= saved_col_access;

    return false;
  }

  // Restore column access rights
  m_thd->col_access= saved_col_access;

  // Setup the iterator to point at the file list
  m_impl->m_files_list_it.init(m_impl->m_files_list);

  return true;
}


// Return the name of next found file
MYSQL_LEX_STRING* Ndb_find_files_list::next()
{
  return m_impl->m_files_list_it++;
}


// Return the number of found files
uint
Ndb_find_files_list::found_files() const
{
  return m_impl->m_files_list.elements;
}
