Change default to zlib, this has effect only if user has
explicitly requested page compression and then user
naturally expects that pages are really compressed
if they can be compressed.

restarting server with encryption and read-only

buf0buf.cc: Temporary slots used in encryption was calculated
by read_threads * write_threads. However, in read-only mode
write_threads is zero. Correct way is to calculate
(read_threads + write_threads) * max pending IO requests.

in Item_partition_func_safe_string(THD *thd, const char *name_arg,
uint length, CHARSET_INFO *cs= NULL), the 'name_arg' is the value
of the string constant and 'length' is the length of this constant,
so length == strlen(name_arg).

check_that_all_fields_are_given_values() relied on write_set,
but was run too early, before triggers updated write_set.

also, when triggers are present, fields might get values conditionally,
so we need to check that all fields are given values for every row.

1. don't put generated files into ${CMAKE_CURRENT_SOURCE_DIR}
2. policy file name must match the module name (Fedora 24 requirement)

In Debian, the default install is made more secure by omitting the anonymous
user and by making the root account authenticate by unix socket
authentication instead of the default password-less root. However, Debian
hard-codes this change in mysql_install_db, which breaks that program for
other users.

This commit instead implements new general options for mysql_install_db that
can be used by anyone to similarly perform a more secure install:

  --skip-auth-anonymous-user: omits the anonymous user.

  --auth-root-authentication-method=normal: Keeps the existing behaviour
    with a password-less root account. Currently on by default.

  --auth-root-socket-user=USER
  --auth-root-authentication-method=socket: creates the MariaDB root user
    with the name USER (defaults to 'root') and using unix socket
    authentication. This way, only that user has MariaDB root access
    after install.

The idea with --auth-root-authentication-method=normal is that
applications that need this behaviour can give that option explicitly.
Then eventually we could make --auth-root-authentication-method=socket
the default, giving a more secure default installation.

Note that it is perfectly possible to do a secure install with
--auth-root-authentication-method=normal. For example, installing a
private server just for local access by a single OS-level user, by
using --skip-networking and putting the connection socket in a
location without public access. So it is important to preserve this
API for backwards compatibility.

        strict_password_validation variable now has
        no effect in the slave thread.

Gtid_list_log_event::do_apply_event() did not free_root(thd->mem_root).
It can allocate on this in record_gtid(), and in some scenarios there is
nothing else that does free_root(), leading to temporary memory leak until
stop of SQL thread. One scenario is in circular replication with only one
master active. The active master receives only its own events on the slave,
all of which are ignored. But whenever the SQL thread catches up with the IO
thread, a Gtid_list_log_event is applied, leading to the leak.

* Remove duplicate lines from tests
* Use thd instead of current_thd
* Remove extra wsrep_binlog_format_names
* Correctly merge union patch from 5.5 wrt duplicate rows.
* Correctly merge SELinux changes into 10.1

The function fsp_flags_try_adjust(), which is called on startup,
is incrementing the Innodb_pages0_read counts for every affected file.
Adjust the result of encryption.innodb_lotoftables accordingly.

Make sure printing with snprintf uses the correct typed parameters.

Make sure printing with snprintf uses the correct typed parameters.

Extra merge due to more extra commits during merge process

innodb.doublewrite: Similar to what was done to innodb.101_compatibility,
add an explicit $_ parameter to the Perl unpack function.
Also, fix some diagnostic messages in the Perl code.

innodb.innodb-wl5522-debug: Adjust for the changed error codes and
messages on fault injection.

Apparently, in older versions of Perl unpack does not have a logic
for using $_ as a default value for the second argument. Fixed by
specifying it explicitly

MariaDB 10.0/MySQL 5.6 using innodb-page-size!=16K

The storage format of FSP_SPACE_FLAGS was accidentally broken
already in MariaDB 10.1.0. This fix is bringing the format in
line with other MySQL and MariaDB release series.

Please refer to the comments that were added to fsp0fsp.h
for details.

This is an INCOMPATIBLE CHANGE that affects users of
page_compression and non-default innodb_page_size. Upgrading
to this release will correct the flags in the data files.
If you want to downgrade to earlier MariaDB 10.1.x, please refer
to the test innodb.101_compatibility how to reset the
FSP_SPACE_FLAGS in the files.

NOTE: MariaDB 10.1.0 to 10.1.20 can misinterpret
uncompressed data files with innodb_page_size=4k or 64k as
compressed innodb_page_size=16k files, and then probably fail
when trying to access the pages. See the comments in the
function fsp_flags_convert_from_101() for detailed analysis.

Move PAGE_COMPRESSION to FSP_SPACE_FLAGS bit position 16.
In this way, compressed innodb_page_size=16k tablespaces will not
be mistaken for uncompressed ones by MariaDB 10.1.0 to 10.1.20.

Derive PAGE_COMPRESSION_LEVEL, ATOMIC_WRITES and DATA_DIR from the
dict_table_t::flags when the table is available, in
fil_space_for_table_exists_in_mem() or fil_open_single_table_tablespace().
During crash recovery, fil_load_single_table_tablespace() will use
innodb_compression_level for the PAGE_COMPRESSION_LEVEL.

FSP_FLAGS_MEM_MASK: A bitmap of the memory-only fil_space_t::flags
that are not to be written to FSP_SPACE_FLAGS. Currently, these will
include PAGE_COMPRESSION_LEVEL, ATOMIC_WRITES and DATA_DIR.

Introduce the macro FSP_FLAGS_PAGE_SSIZE(). We only support
one innodb_page_size for the whole instance.

When creating a dummy tablespace for the redo log, use
fil_space_t::flags=0. The flags are never written to the redo log files.

Remove many FSP_FLAGS_SET_ macros.

dict_tf_verify_flags(): Remove. This is basically only duplicating
the logic of dict_tf_to_fsp_flags(), used in a debug assertion.

fil_space_t::mark: Remove. This flag was not used for anything.

fil_space_for_table_exists_in_mem(): Remove the unnecessary parameter
mark_space, and add a parameter for table flags. Check that
fil_space_t::flags match the table flags, and adjust the (memory-only)
flags based on the table flags.

fil_node_open_file(): Remove some redundant or unreachable conditions,
do not use stderr for output, and avoid unnecessary server aborts.

fil_user_tablespace_restore_page(): Convert the flags, so that the
correct page_size will be used when restoring a page from the
doublewrite buffer.

fil_space_get_page_compressed(), fsp_flags_is_page_compressed(): Remove.
It suffices to have fil_space_is_page_compressed().

FSP_FLAGS_WIDTH_DATA_DIR, FSP_FLAGS_WIDTH_PAGE_COMPRESSION_LEVEL,
FSP_FLAGS_WIDTH_ATOMIC_WRITES: Remove, because these flags do not
exist in the FSP_SPACE_FLAGS but only in memory.

fsp_flags_try_adjust(): New function, to adjust the FSP_SPACE_FLAGS
in page 0. Called by fil_open_single_table_tablespace(),
fil_space_for_table_exists_in_mem(), innobase_start_or_create_for_mysql()
except if --innodb-read-only is active.

fsp_flags_is_valid(ulint): Reimplement from the scratch, with
accurate comments. Do not display any details of detected
inconsistencies, because the output could be confusing when
dealing with MariaDB 10.1.x data files.

fsp_flags_convert_from_101(ulint): Convert flags from buggy
MariaDB 10.1.x format, or return ULINT_UNDEFINED if the flags
cannot be in MariaDB 10.1.x format.

fsp_flags_match(): Check the flags when probing files.
Implemented based on fsp_flags_is_valid()
and fsp_flags_convert_from_101().

dict_check_tablespaces_and_store_max_id(): Do not access the
page after committing the mini-transaction.

IMPORT TABLESPACE fixes:

AbstractCallback::init(): Convert the flags.

FetchIndexRootPages::operator(): Check that the tablespace flags match the
table flags. Do not attempt to convert tablespace flags to table flags,
because the conversion would necessarily be lossy.

PageConverter::update_header(): Write back the correct flags.
This takes care of the flags in IMPORT TABLESPACE.

contains a bad and a good copy

Clean up the InnoDB doublewrite buffer code.

buf_dblwr_init_or_load_pages(): Do not add empty pages to the buffer.

buf_dblwr_process(): Do consider changes to pages that are all zero.
Do not abort when finding a corrupted copy of a page in the doublewrite
buffer, because there could be multiple copies in the doublewrite buffer,
and only one of them needs to be good.

sometimes table->s->stored_fields is less than table->s->null_fields

safe_mutex: Found wrong usage of mutex 'LOCK_thread_count' and 'LOCK_status'
Mutex currently locked (in reverse order):
LOCK_status        sql/sql_class.h  line 3873
LOCK_thread_count  libmysqld/lib_sql.cc  line 432

It was used for get_datetime_value() and for thd->is_error().

But in fact, get_datetime_value() never used thd argument, because the
cache ptr argument was NULL. And thd->is_error() check was not needed
at that place at all.

it used current_thd->alloc() and allocated on the thd's execution arena,
not on table->expr_arena.

Remove THD::arena_for_cached_items that is temporarily set in
update_virtual_fields(), and replaces THD arena in get_datetime_value().
Instead set THD arena to table->expr_arena for the whole  duration
of update_virtual_fields()

Item_func_le included Arg_comparator. Arg_comparator remembered
the current_thd during fix_fields and used that value during
execution to allocate Item_cache in get_datetime_value().
But for vcols fix_fields and val_int can happen in different threads.

Same bug for Item_func_in using in_datetime or cmp_item_datetime,
both also remembered current_thd at fix_fields() to use it later
for get_datetime_value().

As a fix, these objects no longer remember the current_thd,
and get_datetime_value() uses current_thd at run time. This
should not increase the number of current_thd calls much, as
Item_cache is created only once anyway.

don't check defaults for vcols