Use temporary constraint names for temporary tables. The constraints
are not added to cache (skipped in dict_table_rename_in_cache()).

The scheme for temporary constraint names is as follows:

    for old table: db_name/\xFFconstraint_name
    for new table: db_name/\xFF\xFFconstraint_name

normalize_table_name_c_low(): wrong comparison "less than FN_REFLEN -
1". Somewhere array of FN_REFLEN includes the trailing 0, somewhere
array of FN_REFLEN + 1 includes trailing 0, but nowhere array of
FN_REFLEN - 1 must include trailing 0.

All InnoDB internal SQL functions should be moved to sql_funcs.h

add_back_last_deleted_lock() was called when the lock was never
removed. Lock is removed in finalize_atomic_replace() in
close_all_tables_for_name(). finalize_atomic_replace() is done only
for successful operation.

In non-atomic codepath it drops the table first, if anything fails
later we don't need to return back the lock since there is no table
now. So the fix is required as well.

Related to MDEV-24176.

1. vcol_fix_expr() generates new tree changes:
Type_std_attributes::agg_item_set_converter() does change_item_tree().

The changes are allocated on expr_arena (via Vcol_expr_context as per
MDEV-24176).

2. vcol_cleanup_expr() doesn't remove these changes (can be a bug of
Type_std_attributes or per design).

3. Atomic CREATE OR REPLACE renames old table to backup
(finalize_atomic_replace()). It does that via
rename_table_and_triggers() and that closes table share and releases
expr_arena root. Hence now we have Item corpses in thd->change_list.

4. PS cleanup phase tries to rollback thd->change_list and accesses
already freed item corpses.

The fix saves and restores change_list on
vcol_fix_expr()/vcol_cleanup_expr().

Also fixes wrong rollback of ddl_log_state_rm in case of non-atomic
replace. There is no backup to remove in that case.

Separate backup_log_print per each test case group.

Atomic CREATE OR REPLACE allows to keep an old table intact if the
command fails or during the crash. That is done through creating
a table with a temporary name and filling it with the data
(for CREATE OR REPLACE .. SELECT), then renaming the original table
to another temporary (backup) name and renaming the replacement table
to original table. The backup table is kept until the last chance of
failure and if that happens, the replacement table is thrown off and
backup recovered. When the command is complete and logged the backup
table is deleted.

Atomic replace algorithm

  Two DDL chains are used for CREATE OR REPLACE:
  ddl_log_state_create (C) and ddl_log_state_rm (D).

  1. (C) Log CREATE_TABLE_ACTION of TMP table (drops TMP table);
  2. Create new table as TMP;
  3. Do everything with TMP (like insert data);

  finalize_atomic_replace():
  4. Link chains: (D) is executed only if (C) is closed;
  5. (D) Log DROP_ACTION of BACKUP;
  6. (C) Log RENAME_TABLE_ACTION from ORIG to BACKUP (replays BACKUP -> ORIG);
  7. Rename ORIG to BACKUP;
  8. (C) Log CREATE_TABLE_ACTION of ORIG (drops ORIG);
  9. Rename TMP to ORIG;

  finalize_ddl() in case of success:
  10. Close (C);
  11. Replay (D): BACKUP is dropped.

  finalize_ddl() in case of error:
  10. Close (D);
  11. Replay (C):
    1) ORIG is dropped (only after finalize_atomic_replace());
    2) BACKUP renamed to ORIG (only after finalize_atomic_replace());
    3) drop TMP.

  If crash happens (C) or (D) is replayed in reverse order. (C) is
  replayed if crash happens before it is closed, otherwise (D) is
  replayed.

Temporary table for CREATE OR REPLACE

  Before dropping "old" table, CREATE OR REPLACE creates "tmp" table.
  ddl_log_state_create holds the drop of the "tmp" table.  When
  everything is OK (data is inserted, "tmp" is ready) ddl_log_state_rm
  is written to replace "old" with "tmp". Until ddl_log_state_create
  is closed ddl_log_state_rm is not executed.

  After the binlogging is done ddl_log_state_create is closed. At that
  point ddl_log_state_rm is executed and "tmp" is replaced with
  "old". That is: final rename is done by the DDL log.

  With that important role of DDL log for CREATE OR REPLACE operation
  replay of ddl_log_state_rm must fail at the first hit error and
  print the error message if possible. F.ex. foreign key error is
  discovered at this phase: InnoDB rejects to drop the "old" table and
  returns corresponding foreign key error code.

Additional notes

  - CREATE TABLE without REPLACE is not affected by this commit.

  - Engines having HTON_EXPENSIVE_RENAME flag set are not affected by
    this commit.

  - CREATE TABLE .. SELECT XID usage is fixed and now there is no need
    to log DROP TABLE via DDL_CREATE_TABLE_PHASE_LOG (see comments in
    do_postlock()). XID is now correctly updated so it disables
    DDL_LOG_DROP_TABLE_ACTION. Note that binary log is flushed at the
    final stage when the table is ready. So if we have XID in the
    binary log we don't need to drop the table.

  - Three variations of CREATE OR REPLACE handled:

    1. CREATE OR REPLACE TABLE t1 (..);
    2. CREATE OR REPLACE TABLE t1 LIKE t2;
    3. CREATE OR REPLACE TABLE t1 SELECT ..;

  - Test case uses 6 combinations for engines (aria, aria_notrans,
    myisam, ib, lock_tables, expensive_rename) and 2 combinations for
    binlog types (row, stmt). Combinations help to check differences
    between the results. Error failures are tested for the above three
    variations.

  - expensive_rename tests CREATE OR REPLACE without atomic
    replace. The effect should be the same as with the old behaviour
    before this commit.

  - Triggers mechanism is unaffected by this change. This is tested in
    create_replace.test.

  - LOCK TABLES is affected. Lock restoration must be done after "rm"
    chain is replayed.

  - Moved ddl_log_complete() from send_eof() to finalize_ddl(). This
    checkpoint was not executed before for normal CREATE TABLE but is
    executed now.

  - CREATE TABLE will now rollback also if writing to the binary
    logging failed. See rpl_gtid_strict.test

Rename and drop via DDL log

  We replay ddl_log_state_rm to drop the old table and rename the
  temporary table. In that case we must throw the correct error
  message if ddl_log_revert() fails (f.ex. on FK error).

  If table is deleted earlier and not via DDL log and the crash
  happened, the create chain is not closed. Linked drop chain is not
  executed and the new table is not installed. But the old table is
  already deleted.

ddl_log.cc changes

  Now we can place action before DDL_LOG_DROP_INIT_ACTION and it will
  be replayed after DDL_LOG_DROP_TABLE_ACTION.

  report_error parameter for ddl_log_revert() allows to fail at first
  error and print the error message if possible.
  ddl_log_execute_action() now can print error message.

  Since we now can handle errors from ddl_log_execute_action() (in
  case of non-recovery execution) unconditional setting "error= TRUE"
  is wrong (it was wrong anyway because it was overwritten at the end
  of the function).

On XID usage

  Like with all other atomic DDL operations XID is used to avoid
  inconsistency between master and slave in the case of a crash after
  binary log is written and before ddl_log_state_create is closed. On
  recovery XIDs are taken from binary log and corresponding DDL log
  events get disabled.  That is done by
  ddl_log_close_binlogged_events().

On linking two chains together

  Chains are executed in the ascending order of entry_pos of execute
  entries. But entry_pos assignment order is undefined: it may assign
  bigger number for the first chain and then smaller number for the
  second chain. So the execution order in that case will be reverse:
  second chain will be executed first.

  To avoid that we link one chain to another. While the base chain
  (ddl_log_state_create) is active the secondary chain
  (ddl_log_state_rm) is not executed. That is: only one chain can be
  executed in two linked chains.

  The interface ddl_log_link_chains() was done in "MDEV-22166
  ddl_log_write_execute_entry() extension".

More on CREATE OR REPLACE .. SELECT

  We use create_and_open_tmp_table() like in ALTER TABLE to create
  temporary TABLE object (tmp_table is (NON_)TRANSACTIONAL_TMP_TABLE).

  After we created such TABLE object we use create_info->tmp_table()
  instead of table->s->tmp_table when we need to check for
  parser-requested tmp-table.

  External locking is required for temporary table created by
  create_and_open_tmp_table(). F.ex. that disables logging for Aria
  transactional tables and without that (when no mysql_lock_tables()
  is done) it cannot work correctly.

  For making external lock the patch requires Aria table to work in
  non-transactional mode. That is usually done by
  ha_enable_transaction(false). But we cannot disable transaction
  completely because: 1. binlog rollback removes pending row events
  (binlog_remove_pending_rows_event()). The row events are added
  during CREATE .. SELECT data insertion phase. 2. replication slave
  highly depends on transaction and cannot work without it.

  So we put temporary Aria table into non-transactional mode with
  "thd->transaction->on hack". See comment for on_save variable.

  Note that Aria table has internal_table mode. But we cannot use it
  because:

  if (!internal_table)
  {
    mysql_mutex_lock(&THR_LOCK_myisam);
    old_info= test_if_reopen(name_buff);
  }

  For internal_table test_if_reopen() is not called and we get a new
  MARIA_SHARE for each file handler. In that case duplicate errors are
  missed because insert and lookup in CREATE .. SELECT is done via two
  different handlers (see create_lookup_handler()).

  For temporary table before dropping TABLE_SHARE by
  drop_temporary_table() we must do ha_reset(). ha_reset() releases
  storage share. Without that the share is kept and the second CREATE
  OR REPLACE .. SELECT fails with:

    HA_ERR_TABLE_EXIST (156): MyISAM table '#sql-create-b5377-4-t2' is
    in use (most likely by a MERGE table). Try FLUSH TABLES.

    HA_EXTRA_PREPARE_FOR_DROP also removes MYISAM_SHARE, but that is
    not needed as ha_reset() does the job.

  ha_reset() is usually done by
  mark_tmp_table_as_free_for_reuse(). But we don't need that mechanism
  for our temporary table.

Atomic_info in HA_CREATE_INFO

  Many functions in CREATE TABLE pass the same parameters. These
  parameters are part of table creation info and should be in
  HA_CREATE_INFO (or whatever). Passing parameters via single
  structure is much easier for adding new data and
  refactoring.

InnoDB changes (revised by Marko Mäkelä)

  row_rename_table_for_mysql(): Specify the treatment of FOREIGN KEY
  constraints in a 4-valued enum parameter. In cases where FOREIGN KEY
  constraints cannot exist (partitioned tables, or internal tables of
  FULLTEXT INDEX), we can use the mode RENAME_IGNORE_FK.
  The mod RENAME_REBUILD is for any DDL operation that rebuilds the
  table inside InnoDB, such as TRUNCATE and native ALTER TABLE
  (or OPTIMIZE TABLE). The mode RENAME_ALTER_COPY is used solely
  during non-native ALTER TABLE in ha_innobase::rename_table().
  Normal ha_innobase::rename_table() will use the mode RENAME_FK.

  CREATE OR REPLACE will rename the old table (if one exists) along
  with its FOREIGN KEY constraints into a temporary name. The replacement
  table will be initially created with another temporary name.
  Unlike in ALTER TABLE, all FOREIGN KEY constraints must be renamed
  and not inherited as part of these operations, using the mode RENAME_FK.

  dict_get_referenced_table(): Let the callers convert names when needed.

  create_table_info_t::create_foreign_keys(): CREATE OR REPLACE creates
  the replacement table with a temporary name table, so for
  self-references foreign->referenced_table will be a table with
  temporary name and charset conversion must be skipped for it.

Reviewed by:

  Michael Widenius <monty@mariadb.org>

create_table duplicates select_insert::table_list. Since select_create
inherits select_insert and the functional role of the members is the
same we should remove one to eliminate the need of keeping them in
sync.

TABLE_SHARE, TABLE_LIST inherit Table_name

rename_table_and_triggers(), rename_check_preconditions() use
Table_name instead TABLE_LIST.

TODO:
  - Table_ident should inherit Table_name too;
  - Use TABLE_SHARE::alias instead of TABLE::alias.

TABLEOP_HOOKS is a strange interface: proxy interface calls virtual
interface. Since it is used only for select_create::prepare() such
complexity is overwhelming.

Removed default values for arguments, added flags argument to specify
filename flags (FN_TO_IS_TMP, FN_FROM_IS_TMP).

ddl_log_write_execute_entry() cleanup

Rename functions renamed:
  do_rename() -> rename_table_and_triggers()
  do_rename_temporary() -> rename_temporary_table()
  check_rename() -> rename_check_preconditions()

There is a need in MDEV-25292 to have both C_ALTER_TABLE and
select_field_count in one call. Semantically creation mode and field
count are two different things. Making creation mode negative
constants and field count positive variable into one parameter seems
to be a lazy hack for not making the second parameter.

select_count does not make sense without alter_info->create_list, so
the natural way is to hold it in Alter_info too. select_count is now
stored in member select_field_count.

FreeBSD has libexecinfo as a system library.

Add ORDER BY to make the test deterministic.

Add FLUSH TABLES to avoid crash recovery warnings about the table
mysql.plugin. This tends to occur on Valgrind, where the server
shutdown could presumably time out, resulting in a forced kill.

dict_table_rename_in_cache(), dict_table_get_highest_foreign_id():
Reserve sufficient space for the fkid[] buffer, and ensure that the
fkid[] will be NUL-terminated.

The fkid[] must accommodate both the database name (which is already
encoded in my_charset_filename) and the constraint name
(which must be converted to my_charset_filename) so that we can check
if it is in the format databasename/tablename_ibfk_1 (all encoded in
my_charset_filename).

Modern software (including text editors, static analysis software,
and web-based code review interfaces) often requires source code files
to be interpretable via a consistent character encoding, with UTF-8 or
ASCII (a strict subset of UTF-8) as the default. Several of the MariaDB
source files contain bytes that are not valid in either the UTF-8 or
ASCII encodings, but instead represent strings encoded in the
ISO-8859-1/Latin-1 or ISO-8859-2/Latin-2 encodings.

These inconsistent encodings may prevent software from correctly
presenting or processing such files. Converting all source files to
valid UTF8 characters will ensure correct handling.

Comments written in Czech were replaced with lightly-corrected
translations from Google Translate. Additionally, comments describing
the proper handling of special characters were changed so that the
comments are now purely UTF8.

All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer
Amazon Web Services, Inc.
Co-authored-by: Andrew Hutchings <andrew@linuxjedi.co.uk>

trx_undo_page_report_rename(): Use the correct maximum length of
a table name. Both the database name and the table name can be up to
NAME_CHAR_LEN (64 characters) times 5 bytes per character in the
my_charset_filename encoding. They are not encoded in UTF-8!

fil_op_write_log(): Reserve the correct amount of log buffer for
a rename operation. The file name will be appended by
mlog_catenate_string().

rename_file_ext(): Reserve a large enough buffer for the file names.

take into account C/C specific CR_ERR_NET_WRITE error

MDEV-18873 Server crashes in Compare_identifiers::operator or in my_strcasecmp_utf8 upon ADD PERIOD IF NOT EXISTS with empty name

empty identifier specified as `` ends up with a NULL LEX_CSTRING::str in lexer.
This is not considered correct in upper layers, for example in Compare_identifiers::operator().
Empty column name is usually avoided by a check_column_name() call while parsing,
and period name matches the column name completely.
Hence, this fix uses the mentioned call for verification, too.

In commit 0b47c126 (MDEV-13542)
a few calls to mtr_t::memo_push() were moved before a write latch
on the page was acquired. This introduced a race condition:

1. is_block_dirtied() returned false to mtr_t::memo_push()
2. buf_page_t::write_complete() was executed, the block marked clean,
and a page latch released
3. The page latch was acquired by the caller of mtr_t::memo_push(),
and mtr_t::m_made_dirty was not set even though the block is in
a clean state.

The impact of this race condition is that crash recovery and backups
may fail.

btr_cur_latch_leaves(), btr_store_big_rec_extern_fields(),
btr_free_externally_stored_field(), trx_purge_free_segment():
Acquire the page latch before invoking mtr_t::memo_push().
This fixes the regression caused by MDEV-13542.

Side note: It would suffice to set mtr_t::m_made_dirty at the time
we set the MTR_MEMO_MODIFY flag for a block. Currently that flag is
unnecessarily set if a mini-transaction acquires a page latch on
a page that is in a clean state, and will not actually modify the block.
This may cause unnecessary acquisitions of log_sys.flush_order_mutex
on mtr_t::commit().

mtr_t::free(): If the block had been exclusively latched in this
mini-transaction, set the m_made_dirty flag so that the flush order mutex
will be acquired during mtr_t::commit(). This should have been part of
commit 4179f93d (MDEV-18976).
It was necessary to change mtr_t::free() so that
WriteOPT_PAGE_CHECKSUM::operator() would be able to avoid writing
checksums for freed pages.

Since the 10.5 split of the privileges, the required GRANTs
for various mariabackup operations has changed.

In the addition of tests, a number of mappings where incorrect:

The option --lock-ddl-per-table didn't require connection admin.

The option --safe-slave-backup requires SLAVE MONITOR even without
the --no-lock option.

This bug affected some queries with an IN/ALL/ANY predicand or an EXISTS
predicate whose subquery contained a GROUP BY clause that could be
eliminated. If this clause used a IN/ALL/ANY predicand whose left operand
was a single-value subquery then execution of the query caused a crash of
the server after invokation of remove_redundant_subquery_clauses().
The crash was caused by an attempt to exclude the unit for the single-value
subquery from the query tree for the second time by the function
Item_subselect::eliminate_subselect_processor().

This bug had been masked by the bug MDEV-28617 until a fix for the latter
that properly excluded units was pushed into 10.3.

Approved by Oleksandr Byelkin <sanja@mariadb.com>