It turns out that we must check for DISCARD TABLESPACE both
when the table is being rebuilt and when the AUTO_INCREMENT
value of the table is being added.

This was caught by the test innodb.alter_missing_tablespace.
Somehow I failed to run all tests. Sorry!

The statement ALTER TABLE...DISCARD TABLESPACE is problematic,
because its designed purpose is to break the referential integrity
of the data dictionary and make a table point to nowhere.

ha_innobase::commit_inplace_alter_table(): Check whether the
table has been discarded. (This is a bit late to check it, right
before committing the change.) Previously, we performed this check
only in a specific branch of the function commit_set_autoinc().

Note: We intentionally allow non-rebuilding ALTER TABLE even if
the tablespace has been discarded, to remain compatible with MySQL.
(See the various tests with "wl5522" in the name, such as
innodb.innodb-wl5522.)

The test case would crash starting with 10.3 only, but it does not hurt
to minimize the code and test difference between 10.2 and 10.3.

dict_load_table_low(): Copy the 'discarded' flag to file_unreadable.
This allows to avoid a potentially harmful call to dict_stats_init()
in ha_innobase::open().

The test that was added in commit e05650e6
would break a subsequent run of a test encryption.innodb-bad-key-change
because some pages in the system tablespace would be encrypted with
a different key.

The failure was repeatable with the following invocation:

./mtr --no-reorder \
encryption.create_or_replace,cbc \
encryption.innodb-bad-key-change,cbc

Because the crash was unrelated to the code changes that we reverted
in commit eb38b1f7
we can safely re-apply those fixes.

Add error printout when mysql.wsrep_streaming_log lock
fails. However, tests are very undeterministic and not
suitable for mtr environment. Thus, they are removed.

After DISCARD TABLESPACE, the tablespace of a table will no longer
exist, and dict_get_and_save_data_dir_path() would invoke
dict_get_first_path() to read an entry from SYS_DATAFILES.
For some reason, DISCARD TABLESPACE would not to remove the entry
from there.

dict_get_and_save_data_dir_path(): If the tablespace has been
discarded, do not bother trying to read the name.

Side note: The tables SYS_TABLESPACES and SYS_DATAFILES are
redundant and subject to removal in MDEV-22343.

This reverts commit e33f7b6f.
The change seems to have introduced intermittent failures of the test
encryption.innodb-bad-key-change on many platforms.

The failure that we were trying to address was not reproduced on 10.2.
It could be related to commit a7dd7c89
(MDEV-23651) or de942c9f (MDEV-15983)
or other changes that reduced contention on fil_system.mutex in 10.3.

The fix that we are hereby reverting from 10.2 seems to work fine
on 10.3 and 10.4.

This is just to make sure no ExecStartPre/Post actions from the
multi-instance MariaDB service definition are executed
when a user attempts to start mariadb@bootstrap.

Fixes: 3723c70a

We omit commit a3bdce8f
and commit a0e2a293
because they would make the test galera_3nodes.galera_gtid_2_cluster
fail and disable it.

This was forgotten in commit a9d8f5c1.

Let us shrink the test encryption.create_or_replace so that it can
run on the CI system, also on the embedded server.

encryption.create_or_replace_big: Renamed from the original test,
with the subset of encryption.create_or_replace omitted.

The test encryption.create_or_replace would occasionally fail with
a warning message from fil_check_pending_ops().

fil_crypt_find_space_to_rotate(): While waiting for available
I/O capacity, check fil_space_t::is_stopping() and release a
handle if necessary.

fil_space_crypt_close_tablespace(): Wake up the waiters in
fil_crypt_find_space_to_rotate().

log_group_read_log_seg() returns error when:

1) Calculated log block number does not correspond to read log block
number. This can be caused by:
  a) Garbage or an incompletely written log block. We can exclude this
  case by checking log block checksum if it's enabled(see innodb-log-checksums,
  encrypted log block contains checksum always).
  b) The log block is overwritten. In this case checksum will be correct and
  read log block number will be greater then requested one.

2) When log block length is wrong. In this case recv_sys->found_corrupt_log
is set.

3) When redo log block checksum is wrong. In this case innodb code
writes messages to error log with the following prefix: "Invalid log
block checksum."

The fix processes all the cases above.

Fix assertion text it was too tight for some systems.

This is backport from 10.4 and for Galera 3.

Fix assertion text it was too tight for some systems.

The presumed reason for the error is that the file was opened
by 3rd party antivirus or backup program, causing ERROR_SHARING_VIOLATION
on rename.

The fix, actually a workaround, is to retry MoveFileEx couple of times
before finally giving up. We expect 3rd party programs not to hold file
for extended time.

MDEV-23574 : galera_3nodes.galera_ipv6_mariabackup_section MTR failed: Could not open '../galera/include/have_mariabackup.inc'

Test case and configuration cleanup.

Add wait_condition to wait correct cluster configuration.

MDEV-21655 : galera.galera_wan_restart_ist MTR fails sporadically: WSREP did not transition to state READY

Replace sleeps with proper wait_conditions to wait correct
cluster configuration.

Problem:
=======
SHOW BINLOG EVENTS FROM <"random"-pos> caused a variety of failures as
reported in MDEV-18046. They are fixed but that approach is not future-proof
as well as is not optimal to create extra check for being constructed event
parameters.

Analysis:
=========
"show binlog events from <pos>" code considers the user given position as a
valid event start position. The code starts reading data from this event start
position onwards and tries to map it to a set of known events. Each event has
a specific event structure and asserts have been added to ensure that, read
event data, satisfies the event specific requirements. When a random position
is supplied to "show binlog events command" the event structure specific
checks will fail and they result in assert.

For example: https://jira.mariadb.org/browse/MDEV-18046
In the bug description user executes CREATE TABLE/INSERT and ALTER SQL
commands.

When a crazy offset like "SHOW BINLOG EVENTS FROM 365" is provided code
assumes offset 365 as valid event begin and proceeds to EVENT_LEN_OFFSET reads
some random length and comes up with a crazy event which didn't exits in the
binary log. In this quoted example scenario, event read at offset 365 is
considered as "Update_rows_log_event", which is not present in binary log.
Since this is a random event its validation fails and code results in
assert/segmentation fault, as shown below.

mysqld: /data/src/10.4/sql/log_event.cc:10863: Rows_log_event::Rows_log_event(
    const char*, uint, const Format_description_log_event*):
    Assertion `var_header_len >= 2' failed.
    181220 15:27:02 [ERROR] mysqld got signal 6 ;
#7  0x00007fa0d96abee2 in __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6
#8  0x000055e744ef82de in Rows_log_event::Rows_log_event (this=0x7fa05800d390,
    buf=0x7fa05800d080 "", event_len=254, description_event=0x7fa058006d60) at
/data/src/10.4/sql/log_event.cc:10863
#9  0x000055e744f00cf8 in Update_rows_log_event::Update_rows_log_event

Since we are reading random data repeating the same command SHOW BINLOG EVENTS
FROM 365 produces different types of crashes with different events. MDEV-18046
reported 10 such crashes.

In order to avoid such scenarios user provided starting offset needs to be
validated for its correctness. Best way of doing this is to make use of
checksums if they are available. MDEV-18046 fix introduced the checksum based
validation.

The issue still remains in cases where binlog checksums are disabled. Please
find the following bug reports.

MDEV-22473: binlog.binlog_show_binlog_event_random_pos failed in buildbot,
            server crashed in read_log_event
MDEV-22455: Server crashes in Table_map_log_event,
            binlog.binlog_invalid_read_in_rotate failed in buildbot

Fix:
====
When binlog checksum is disabled, perform scan(via reading event by event), to
validate the requested FROM <pos> offset. Starting from offset 4 read the
event_length of next_event in the binary log. Using the next_event length
advance current offset to point to next event. Repeat this process till the
current offset is less than or equal to crazy offset. If current offset is
higher than crazy offset provide appropriate invalid input offset error.

Made the test work with --repeat option by adding
galera_wait_ready.inc at the end of test. Recorded the test output.

MDEV-23617 : galera_sr.galera_sr_rollback_retry MTR failed: 1213: Deadlock found when trying to get lock

Add corrected wait_condition to wait until rows are in streaming
replication log.

Parse SHOW SLAVE STATUS output for the "Using_Gtid" column. If the value
is "No", then old log file and position is backed up, otherwise gtid_slave_pos
is backed up.