in a specially crafted invalid packet, one can get end_pos < pos here

disable online alter add primary key for innodb, if the
table is opened/locked more than once in the current connection

(see assert in ha_innobase::add_index())

test case

Any expensive WHERE condition for a table-less query with
implicit aggregation was lost. As a result the used aggregate
functions were calculated over a non-empty set of rows even
in the case when the condition was false.

Also clarify which --{no-,}default* options, must be first.

Sample output:
$  client/mysql --help
client/mysql  Ver 15.1 Distrib 5.5.59-MariaDB, for Linux (x86_64) using readline 5.1
Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Usage: client/mysql [OPTIONS] [database]

Default options are read from the following files in the given order:
/etc/my.cnf /etc/mysql/my.cnf ~/.my.cnf
The following groups are read: mysql client client-server client-mariadb
The following options may be given as the first argument:
--print-defaults          Print the program argument list and exit.
--no-defaults             Don't read default options from any option file.
The following specify which files/groups are read (specified before other options):
--defaults-file=#         Only read default options from the given file #.
--defaults-extra-file=#   Read this file after the global files are read.
--defaults-group-suffix=# Additionally read default groups with # appended as a suffix.

tests running from build directory:
TEST: print defaults ignored as not first
$ sql/mysqld  --no-defaults --print-defaults --lc-messages-dir=${PWD}/sql/share

TEST: no startup occurs as --print-defaults specified
$ sql/mysqld  --print-defaults --lc-messages-dir=${PWD}/sql/share
sql/mysqld would have been started with the following arguments:
--lc-messages-dir=/home/dan/repos/build-mariadb-5.5/sql/share

TEST: default args can't be anywhere
$ client/mysql --user=bob  --defaults-file=/etc/my.cnf
client/mysql: unknown variable 'defaults-file=/etc/my.cnf'
$ client/mysql --user=bob  --defaults-group-suffix=.group
client/mysql: unknown variable 'defaults-group-suffix=.group'

/etc/my.cnf:
[client-server.group]
socket=/var/lib/mysql-multi/group/mysqld.sock
user=bob

/etc/my.other.cnf:
socket=/var/lib/mysql-other/mysqld.sock

TEST: defaults file read and suffix also applied
$  client/mysql  --defaults-file=/etc/my.other.cnf  --defaults-group-suffix=.group
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql-other/mysqld.sock' (2)

TEST: defaults extra file
$ client/mysql  --defaults-extra-file=/etc/my.other.cnf  --defaults-group-suffix=.group
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql-other/mysqld.sock' (2)

condition fixed.

handler::ha_create_handler_files shouldn't call the
mark_trx_read_write() for the temporary table.

MDEV-15624 Changing the default character set to utf8mb4 changes query evaluation in a very surprising way

warning: format '%p' expects argument of type 'void *', but argument 4 has type 'long int'

For this case we have a view that is mergeable but we are not able to merge it in the
parent select because that would exceed the maximum tables allowed in the join list, so we
materialise this view
TABLE_LIST::dervied is NULL for such views, it is only set for views which have ALGORITHM=TEMPTABLE
Fixed by making sure TABLE_LIST::derived is set for views that could not be merged

A simple patch fixing the problem in 5.5.
Note, a full patch was previously fixed to 10.3.

Conversion of a subquery to a semi-join is blocked when we have an
IN subquery predicate in the on_expr of an outer join. Currently this
scenario is handled but the cases when an IN subquery predicate is wrapped
inside a Item_in_optimizer item then this blocking is not done.

Detection of first execution of PS fixed.
More debug info.

For the query having an IN subquery with no tables, we were converting the subquery with an expression between
the left part and the select list of the subquery . This can give incorrect results when we have a condition
in the subquery with a dual table (as this is treated as a no table).

The fix is that we don't do this conversion when we have conds in the subquery with a dual table.

mem_heap_create_block(): Poison the payload area until
mem_heap_alloc() unpoisons it.

Learn both valgrind and asan to catch this bug:

  mem_heap_t* heap = mem_heap_create(1024);
  byte* p = reinterpret_cast<byte*>(heap) + sizeof(mem_heap_t);
  *p = 123;

Overflows of the last allocation in a block will be catched too.

mem_heap_create_block(): poison newly allocated memory

Backport from 10.2

The issue is that we are creating a materialised table with key of length 0 which is incorrect, we should
disable materialisation for such a case.

              PREBUILT->TABLE->N_MYSQL_HANDLES_OPENED == 1

ANALYSIS:
=========

Adding unique index to a InnoDB table which is locked as
mutliple instances may trigger an InnoDB assert.

When we add a primary key or an unique index, we need to
drop the original table and rebuild all indexes. InnoDB
expects that only the instance of the table that is being
rebuilt, is open during the process. In the current
scenario we have opened multiple instances of the table.
This triggers an assert during table rebuild.
'Locked_tables_list' encapsulates a list of all
instances of tables locked by LOCK TABLES statement.

FIX:
===
We are now temporarily closing all the instances of the
table except the one which is being altered and later
reopen them via Locked_tables_list::reopen_tables().

Change the file to refer to published git repository directly

use the correct handlerton when looking for TRANSACTIONAL=1 support

MDEV-13748 Assertion `status_var.local_memory_used == 0 || !debug_assert_on_not_freed_memory' failed in virtual THD::~THD after query with INTERSECT

my_safe_alloca()/my_safe_afree() work as alloca() or malloc()/free()
depending on the memory size to allocate, that is, depending on
reclength here. They only work correctly if reclength doesn't
change in the middle.

No commit message

Description:- Mysql client crashes when trying to connect
to a fake server which is sending incorrect packets.

Analysis:- Mysql client crashes when it tries to read
server version details.

Fix:- A check is added in "red_one_row()".

proper fix replacing the hack from b80fa400

don't confuse length of the data area (reclength) with the
offset to the "deleted" mark.

              PREVIOUS TO MYSQL 8.0

Description :
-------------
The mysqld--defaults-file test fails when the test suite is run from a
non-canonical path, which happens when the current working directory
when mysql-test-run.pl is started contains a symbolic link.

The problem is that this test case uses --replace-result with
$MYSQL_TEST_DIR. This variable is a potentially non-canonical path
based on the current working directory when mtr is started. However,
the path in the expected error message from mysqld contains a
canonical path. This means it does not contain $MYSQL_TEST_DIR if
mtr's working directory is not the canonical path of the working
directory.

Because other tests produce output that may contain non-canonical
paths, making $MYSQL_TEST_DIR always canonical is not a fix.

Fix :
-----
Introduced a new environment variable '$ABS_MYSQL_TEST_DIR' which will
contin the canonical path to the test directory and replaced
$MYSQL_TEST_DIR with the new variable in main.mysqld--defaults-file
test file.

This is a back-port of BUG#24579973.

Change-Id: I3b8df6f2d7ce2b04e188a896d76250cc1addbbc1

Problem
=======

When facing decoding of corrupt binary log files, server may misbehave
without detecting the events corruption.

This patch makes MySQL server more resilient to binary log decoding.

Fixes for events de-serialization and apply
===========================================

@sql/log_event.cc

Query_log_event::Query_log_event: added a check to ensure query length
is respecting event buffer limits.

Query_log_event::do_apply_event: extended a debug print, added a check
to character set to determine if it is "parseable" or not, verified if
database name is valid for system collation.

Start_log_event_v3::do_apply_event: report an error on applying a
non-supported binary log version.

Load_log_event::copy_log_event: added a check to table_name length.

User_var_log_event::User_var_log_event: added checks to avoid reading
out of buffer limits.

User_var_log_event::do_apply_event: reported an sanity check error
properly and added individual sanity checks for variable types that
expect fixed (or minimum) amount of bytes to be read.

Rows_log_event::Rows_log_event: added checks to avoid reading out of
buffer limits.

@sql/log_event_old.cc

Old_rows_log_event::Old_rows_log_event: added a sanity check to avoid
reading out of buffer limits.

@sql/sql_priv.h

Added a sanity check to available_buffer() function.

Whenever one copies an IO_CACHE struct, one must remember to call
setup_io_cache, if not, the IO_CACHE's current_pos and end_pos
self-references will point to the previous struct's memory, which
could go out of scope. Commit 90038693
fixes this problem in a more general fashion by removing the
self-references altogether, but for 5.5 we'll keep the old behaviour.

MDEV-15014 Assertion `m_cache_lock_status == LOCKED_NO_WAIT || m_cache_status == DISABLE_REQUEST' failed in Query_cache::free_cache on startup

The assert guards against not-locked or not-requested query cache
disabling. If during startup we disable query cache, we failed to
request disabling.

To disable debug instrumentation, save and restore the original value
of the variable DEBUG_DBUG. Assigning -d,... will enable the output of
a lot of unrelated DBUG messages to the server error log.