~drizzle-trunk/drizzle/development

/* Copyright (C) 2000-2003 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA */

/* create and drop of databases */

#include "config.h"

#include <fcntl.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <set>

#include <string>

#include <fstream>

#include <drizzled/message/schema.pb.h>

#include "drizzled/error.h"

#include <drizzled/gettext.h>

#include <drizzled/my_hash.h>

#include "drizzled/internal/m_string.h"

#include <drizzled/session.h>

#include <drizzled/db.h>

#include <drizzled/sql_base.h>

#include <drizzled/lock.h>

#include <drizzled/errmsg_print.h>

#include <drizzled/transaction_services.h>

#include <drizzled/message/schema.pb.h>

#include "drizzled/sql_table.h"

#include "drizzled/plugin/storage_engine.h"

#include "drizzled/plugin/authorization.h"

#include "drizzled/global_charset_info.h"

#include "drizzled/pthread_globals.h"

#include "drizzled/charset.h"

#include <boost/thread/mutex.hpp>

#include "drizzled/internal/my_sys.h"

#define MAX_DROP_TABLE_Q_LEN      1024

using namespace std;

namespace drizzled

{

static void change_db_impl(Session *session);

static void change_db_impl(Session *session, SchemaIdentifier &schema_identifier);

/*

  Create a database

  SYNOPSIS

  create_db()

  session		Thread handler

  db		Name of database to create

		Function assumes that this is already validated.

  create_info	Database create options (like character set)

  SIDE-EFFECTS

   1. Report back to client that command succeeded (my_ok)

   2. Report errors to client

   3. Log event to binary log

  RETURN VALUES

  false ok

  true  Error

*/

bool create_db(Session *session, const message::Schema &schema_message, const bool is_if_not_exists)

{

  TransactionServices &transaction_services= TransactionServices::singleton();

  bool error= false;

  /*

    Do not create database if another thread is holding read lock.

    Wait for global read lock before acquiring session->catalog()->schemaLock().

    After wait_if_global_read_lock() we have protection against another

    global read lock. If we would acquire session->catalog()->schemaLock() first,

    another thread could step in and get the global read lock before we

    reach wait_if_global_read_lock(). If this thread tries the same as we

    (admin a db), it would then go and wait on session->catalog()->schemaLock()...

    Furthermore wait_if_global_read_lock() checks if the current thread

    has the global read lock and refuses the operation with

    ER_CANT_UPDATE_WITH_READLOCK if applicable.

  */

  if (session->wait_if_global_read_lock(false, true))

  {

    return false;

  }

  assert(schema_message.has_name());

  assert(schema_message.has_collation());

  // @todo push this lock down into the engine

  {

    boost::mutex::scoped_lock scopedLock(session->catalog().schemaLock());

    // Check to see if it exists already.  

    SchemaIdentifier schema_identifier(schema_message.name());

    if (plugin::StorageEngine::doesSchemaExist(schema_identifier))

    {

      if (not is_if_not_exists)

      {

        my_error(ER_DB_CREATE_EXISTS, schema_identifier);

        error= true;

      }

      else

      {

        push_warning_printf(session, DRIZZLE_ERROR::WARN_LEVEL_NOTE,

                            ER_DB_CREATE_EXISTS, ER(ER_DB_CREATE_EXISTS),

                            schema_message.name().c_str());

        session->my_ok();

      }

    }

    else if (not plugin::StorageEngine::createSchema(schema_message)) // Try to create it 

    {

      my_error(ER_CANT_CREATE_DB, MYF(0), schema_message.name().c_str(), errno);

      error= true;

    }

    else // Created !

    {

      transaction_services.createSchema(session, schema_message);

      session->my_ok(1);

    }

  }

  session->startWaitingGlobalReadLock();

  return error;

}

/* db-name is already validated when we come here */

bool alter_db(Session *session, const message::Schema &schema_message)

{

  TransactionServices &transaction_services= TransactionServices::singleton();

  /*

    Do not alter database if another thread is holding read lock.

    Wait for global read lock before acquiring session->catalog()->schemaLock().

    After wait_if_global_read_lock() we have protection against another

    global read lock. If we would acquire session->catalog()->schemaLock() first,

    another thread could step in and get the global read lock before we

    reach wait_if_global_read_lock(). If this thread tries the same as we

    (admin a db), it would then go and wait on session->catalog()->schemaLock()...

    Furthermore wait_if_global_read_lock() checks if the current thread

    has the global read lock and refuses the operation with

    ER_CANT_UPDATE_WITH_READLOCK if applicable.

  */

  if ((session->wait_if_global_read_lock(false, true)))

    return false;

  bool success;

  {

    boost::mutex::scoped_lock scopedLock(session->catalog().schemaLock());

    SchemaIdentifier schema_idenifier(schema_message.name());

    if (not plugin::StorageEngine::doesSchemaExist(schema_idenifier))

    {

      my_error(ER_SCHEMA_DOES_NOT_EXIST, schema_idenifier);

      return false;

    }

    /* Change options if current database is being altered. */

    success= plugin::StorageEngine::alterSchema(schema_message);

    if (success)

    {

      transaction_services.rawStatement(session, *session->getQueryString());

      session->my_ok(1);

    }

    else

    {

      my_error(ER_ALTER_SCHEMA, schema_idenifier);

    }

  }

  session->startWaitingGlobalReadLock();

  return success;

}

/*

  Drop all tables in a database and the database itself

  SYNOPSIS

    rm_db()

    session			Thread handle

    db			Database name in the case given by user

		        It's already validated and set to lower case

                        (if needed) when we come here

    if_exists		Don't give error if database doesn't exists

    silent		Don't generate errors

  RETURN

    false ok (Database dropped)

    ERROR Error

*/

bool rm_db(Session *session, SchemaIdentifier &schema_identifier, const bool if_exists)

{

  bool error= false;

  /*

    Do not drop database if another thread is holding read lock.

    Wait for global read lock before acquiring session->catalog()->schemaLock().

    After wait_if_global_read_lock() we have protection against another

    global read lock. If we would acquire session->catalog()->schemaLock() first,

    another thread could step in and get the global read lock before we

    reach wait_if_global_read_lock(). If this thread tries the same as we

    (admin a db), it would then go and wait on session->catalog()->schemaLock()...

    Furthermore wait_if_global_read_lock() checks if the current thread

    has the global read lock and refuses the operation with

    ER_CANT_UPDATE_WITH_READLOCK if applicable.

  */

  if (session->wait_if_global_read_lock(false, true))

  {

    return true;

  }

  do

  {

    boost::mutex::scoped_lock scopedLock(session->catalog().schemaLock());

    /* See if the schema exists */

    if (not plugin::StorageEngine::doesSchemaExist(schema_identifier))

    {

      std::string path;

      schema_identifier.getSQLPath(path);

      if (if_exists)

      {

        push_warning_printf(session, DRIZZLE_ERROR::WARN_LEVEL_NOTE,

                            ER_DB_DROP_EXISTS, ER(ER_DB_DROP_EXISTS),

                            path.c_str());

      }

      else

      {

        error= true;

        my_error(ER_DB_DROP_EXISTS, schema_identifier);

        break;

      }

    }

    else

    {

      error= plugin::StorageEngine::dropSchema(*session, schema_identifier);

    }

  } while (0);

  /*

    If this database was the client's selected database, we silently

    change the client's selected database to nothing (to have an empty

    SELECT DATABASE() in the future). For this we free() session->db and set

    it to 0.

  */

  if (not error and schema_identifier.compare(*session->schema()))

    change_db_impl(session);

  session->startWaitingGlobalReadLock();

  return error;

}

/**

  @brief Change the current database and its attributes unconditionally.

  @param session          thread handle

  @param new_db_name  database name

  @param force_switch if force_switch is false, then the operation will fail if

                        - new_db_name is NULL or empty;

                        - OR new database name is invalid

                          (check_db_name() failed);

                        - OR user has no privilege on the new database;

                        - OR new database does not exist;

                      if force_switch is true, then

                        - if new_db_name is NULL or empty, the current

                          database will be NULL, @@collation_database will

                          be set to @@collation_server, the operation will

                          succeed.

                        - if new database name is invalid

                          (check_db_name() failed), the current database

                          will be NULL, @@collation_database will be set to

                          @@collation_server, but the operation will fail;

                        - user privileges will not be checked

                          (Session::db_access however is updated);

                          TODO: is this really the intention?

                                (see sp-security.test).

                        - if new database does not exist,the current database

                          will be NULL, @@collation_database will be set to

                          @@collation_server, a warning will be thrown, the

                          operation will succeed.

  @details The function checks that the database name corresponds to a

  valid and existent database, checks access rights and changes the current

  database with database attributes (@@collation_database session variable,

  Session::db_access).

  This function is not the only way to switch the database that is

  currently employed. When the replication slave thread switches the

  database before executing a query, it calls session->set_db directly.

  However, if the query, in turn, uses a stored routine, the stored routine

  will use this function, even if it's run on the slave.

  This function allocates the name of the database on the system heap: this

  is necessary to be able to uniformly change the database from any module

  of the server. Up to 5.0 different modules were using different memory to

  store the name of the database, and this led to memory corruption:

  a stack pointer set by Stored Procedures was used by replication after

  the stack address was long gone.

  @return Operation status

    @retval false Success

    @retval true  Error

*/

bool change_db(Session *session, SchemaIdentifier &schema_identifier)

{

  if (not plugin::Authorization::isAuthorized(session->user(), schema_identifier))

  {

    /* Error message is set in isAuthorized */

    return true;

  }

  if (not check_db_name(session, schema_identifier))

  {

    std::string path;

    schema_identifier.getSQLPath(path);

    my_error(ER_WRONG_DB_NAME, schema_identifier);

    return true;

  }

  if (not plugin::StorageEngine::doesSchemaExist(schema_identifier))

  {

    my_error(ER_BAD_DB_ERROR, schema_identifier);

    /* The operation failed. */

    return true;

  }

  change_db_impl(session, schema_identifier);

  return false;

}

/**

  @brief Internal implementation: switch current database to a valid one.

  @param session            Thread context.

  @param new_db_name    Name of the database to switch to. The function will

                        take ownership of the name (the caller must not free

                        the allocated memory). If the name is NULL, we're

                        going to switch to NULL db.

  @param new_db_charset Character set of the new database.

*/

static void change_db_impl(Session *session, SchemaIdentifier &schema_identifier)

{

  /* 1. Change current database in Session. */

#if 0

  if (new_db_name == NULL)

  {

    /*

      Session::set_db() does all the job -- it frees previous database name and

      sets the new one.

    */

    session->set_db(NULL, 0);

  }

  else

#endif

  {

    /*

      Here we already have a copy of database name to be used in Session. So,

      we just call Session::reset_db(). Since Session::reset_db() does not releases

      the previous database name, we should do it explicitly.

    */

    session->set_db(schema_identifier.getSchemaName());

  }

}

static void change_db_impl(Session *session)

{

  session->set_db(string());

}

} /* namespace drizzled */