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/* Copyright (c) 2000, 2010, 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 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 */

/*
Atomic rename of table; RENAME TABLE t1 to t2, tmp to t1 [,...]
*/

#include "sql_priv.h"
#include "unireg.h"
#include "sql_rename.h"
#include "sql_cache.h" // query_cache_*
#include "sql_table.h" // build_table_filename
#include "sql_view.h" // mysql_frm_type, mysql_rename_view
#include "sql_trigger.h"
#include "lock.h" // MYSQL_OPEN_SKIP_TEMPORARY
#include "sql_base.h" // tdc_remove_table, lock_table_names,
#include "sql_handler.h" // mysql_ha_rm_tables
#include "datadict.h"

static TABLE_LIST *rename_tables(THD *thd, TABLE_LIST *table_list,
bool skip_error);

static TABLE_LIST *reverse_table_list(TABLE_LIST *table_list);

/*
Every second entry in the table_list is the original name and every
second entry is the new name.
*/

bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent)
{
  bool error= 1;
  bool binlog_error= 0;
  TABLE_LIST *ren_table= 0;
  int to_table;
  char *rename_log_table[2]= {NULL, NULL};
  DBUG_ENTER("mysql_rename_tables");

  /*
Avoid problems with a rename on a table that we have locked or
if the user is trying to to do this in a transcation context
*/

  if (thd->locked_tables_mode || thd->in_active_multi_stmt_transaction())
  {
    my_message(ER_LOCK_OR_ACTIVE_TRANSACTION,
               ER(ER_LOCK_OR_ACTIVE_TRANSACTION), MYF(0));
    DBUG_RETURN(1);
  }

  mysql_ha_rm_tables(thd, table_list);

  if (logger.is_log_table_enabled(QUERY_LOG_GENERAL) ||
      logger.is_log_table_enabled(QUERY_LOG_SLOW))
  {

    /*
Rules for rename of a log table:

IF 1. Log tables are enabled
AND 2. Rename operates on the log table and nothing is being
renamed to the log table.
DO 3. Throw an error message.
ELSE 4. Perform rename.
*/

    for (to_table= 0, ren_table= table_list; ren_table;
         to_table= 1 - to_table, ren_table= ren_table->next_local)
    {
      int log_table_rename= 0;

      if ((log_table_rename=
           check_if_log_table(ren_table->db_length, ren_table->db,
                              ren_table->table_name_length,
                              ren_table->table_name, 1)))
      {
        /*
as we use log_table_rename as an array index, we need it to start
with 0, while QUERY_LOG_SLOW == 1 and QUERY_LOG_GENERAL == 2.
So, we shift the value to start with 0;
*/
        log_table_rename--;
        if (rename_log_table[log_table_rename])
        {
          if (to_table)
            rename_log_table[log_table_rename]= NULL;
          else
          {
            /*
Two renames of "log_table TO" w/o rename "TO log_table" in
between.
*/
            my_error(ER_CANT_RENAME_LOG_TABLE, MYF(0), ren_table->table_name,
                     ren_table->table_name);
            goto err;
          }
        }
        else
        {
          if (to_table)
          {
            /*
Attempt to rename a table TO log_table w/o renaming
log_table TO some table.
*/
            my_error(ER_CANT_RENAME_LOG_TABLE, MYF(0), ren_table->table_name,
                     ren_table->table_name);
            goto err;
          }
          else
          {
            /* save the name of the log table to report an error */
            rename_log_table[log_table_rename]= ren_table->table_name;
          }
        }
      }
    }
    if (rename_log_table[0] || rename_log_table[1])
    {
      if (rename_log_table[0])
        my_error(ER_CANT_RENAME_LOG_TABLE, MYF(0), rename_log_table[0],
                 rename_log_table[0]);
      else
        my_error(ER_CANT_RENAME_LOG_TABLE, MYF(0), rename_log_table[1],
                 rename_log_table[1]);
      goto err;
    }
  }

  if (lock_table_names(thd, table_list, 0, thd->variables.lock_wait_timeout,
                       MYSQL_OPEN_SKIP_TEMPORARY))
    goto err;

  for (ren_table= table_list; ren_table; ren_table= ren_table->next_local)
    tdc_remove_table(thd, TDC_RT_REMOVE_ALL, ren_table->db,
                     ren_table->table_name, FALSE);

  error=0;
  /*
An exclusive lock on table names is satisfactory to ensure
no other thread accesses this table.
*/
  if ((ren_table=rename_tables(thd,table_list,0)))
  {
    /* Rename didn't succeed; rename back the tables in reverse order */
    TABLE_LIST *table;

    /* Reverse the table list */
    table_list= reverse_table_list(table_list);

    /* Find the last renamed table */
    for (table= table_list;
table->next_local != ren_table ;
table= table->next_local->next_local) ;
    table= table->next_local->next_local; // Skip error table
    /* Revert to old names */
    rename_tables(thd, table, 1);

    /* Revert the table list (for prepared statements) */
    table_list= reverse_table_list(table_list);

    error= 1;
  }

  if (!silent && !error)
  {
    binlog_error= write_bin_log(thd, TRUE, thd->query(), thd->query_length());
    if (!binlog_error)
      my_ok(thd);
  }

  if (!error)
    query_cache_invalidate3(thd, table_list, 0);

err:
  DBUG_RETURN(error || binlog_error);
}


/*
reverse table list

SYNOPSIS
reverse_table_list()
table_list pointer to table _list

RETURN
pointer to new (reversed) list
*/
static TABLE_LIST *reverse_table_list(TABLE_LIST *table_list)
{
  TABLE_LIST *prev= 0;

  while (table_list)
  {
    TABLE_LIST *next= table_list->next_local;
    table_list->next_local= prev;
    prev= table_list;
    table_list= next;
  }
  return (prev);
}


/*
Rename a single table or a view

SYNPOSIS
do_rename()
thd Thread handle
ren_table A table/view to be renamed
new_db The database to which the table to be moved to
new_table_name The new table/view name
new_table_alias The new table/view alias
skip_error Whether to skip error

DESCRIPTION
Rename a single table or a view.

RETURN
false Ok
true rename failed
*/

bool
do_rename(THD *thd, TABLE_LIST *ren_table, char *new_db, char *new_table_name,
          char *new_table_alias, bool skip_error)
{
  int rc= 1;
  char name[FN_REFLEN + 1];
  const char *new_alias, *old_alias;
  frm_type_enum frm_type;
  enum legacy_db_type table_type;

  DBUG_ENTER("do_rename");

  if (lower_case_table_names == 2)
  {
    old_alias= ren_table->alias;
    new_alias= new_table_alias;
  }
  else
  {
    old_alias= ren_table->table_name;
    new_alias= new_table_name;
  }
  DBUG_ASSERT(new_alias);

  build_table_filename(name, sizeof(name) - 1,
                       new_db, new_alias, reg_ext, 0);
  if (!access(name,F_OK))
  {
    my_error(ER_TABLE_EXISTS_ERROR, MYF(0), new_alias);
    DBUG_RETURN(1); // This can't be skipped
  }
  build_table_filename(name, sizeof(name) - 1,
                       ren_table->db, old_alias, reg_ext, 0);

  frm_type= dd_frm_type(thd, name, &table_type);
  switch (frm_type)
  {
    case FRMTYPE_TABLE:
      {
        if (!(rc= mysql_rename_table(ha_resolve_by_legacy_type(thd,
                                                               table_type),
                                     ren_table->db, old_alias,
                                     new_db, new_alias, 0)))
        {
          if ((rc= Table_triggers_list::change_table_name(thd, ren_table->db,
                                                          old_alias,
                                                          ren_table->table_name,
                                                          new_db,
                                                          new_alias)))
          {
            /*
We've succeeded in renaming table's .frm and in updating
corresponding handler data, but have failed to update table's
triggers appropriately. So let us revert operations on .frm
and handler's data and report about failure to rename table.
*/
            (void) mysql_rename_table(ha_resolve_by_legacy_type(thd,
                                                                table_type),
                                      new_db, new_alias,
                                      ren_table->db, old_alias, 0);
          }
        }
      }
      break;
    case FRMTYPE_VIEW:
      /*
change of schema is not allowed
except of ALTER ...UPGRADE DATA DIRECTORY NAME command
because a view has valid internal db&table names in this case.
*/
      if (thd->lex->sql_command != SQLCOM_ALTER_DB_UPGRADE &&
          strcmp(ren_table->db, new_db))
        my_error(ER_FORBID_SCHEMA_CHANGE, MYF(0), ren_table->db,
                 new_db);
      else
        rc= mysql_rename_view(thd, new_db, new_alias, ren_table);
      break;
    default:
      DBUG_ASSERT(0); // should never happen
    case FRMTYPE_ERROR:
      my_error(ER_FILE_NOT_FOUND, MYF(0), name, my_errno);
      break;
  }
  if (rc && !skip_error)
    DBUG_RETURN(1);

  DBUG_RETURN(0);

}
/*
Rename all tables in list; Return pointer to wrong entry if something goes
wrong. Note that the table_list may be empty!
*/

/*
Rename tables/views in the list

SYNPOSIS
rename_tables()
thd Thread handle
table_list List of tables to rename
skip_error Whether to skip errors

DESCRIPTION
Take a table/view name from and odd list element and rename it to a
the name taken from list element+1. Note that the table_list may be
empty.

RETURN
false Ok
true rename failed
*/

static TABLE_LIST *
rename_tables(THD *thd, TABLE_LIST *table_list, bool skip_error)
{
  TABLE_LIST *ren_table, *new_table;

  DBUG_ENTER("rename_tables");

  for (ren_table= table_list; ren_table; ren_table= new_table->next_local)
  {
    new_table= ren_table->next_local;
    if (do_rename(thd, ren_table, new_table->db, new_table->table_name,
                  new_table->alias, skip_error))
      DBUG_RETURN(ren_table);
  }
  DBUG_RETURN(0);
}
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