* Cause
No real deadlock, but incomplete conflict detection:

1. Con1-X blocks on Def-X lock (p.2 in test);
2. Def-II-X has to wait Con1-X and here conflict resolution starts (p.3 in test);
3. Conflict resolution goes through a tree of locks:
  a. (Def-II-X, Def-X): ok
  b. (Def-II-X, Con1-X): conflict, traversing from Con1-X
  c. (Con1-X, Def-X): conflict, found cycle (because resolution started from Def).

The weak point here is 2. (lock_rec_has_to_wait()), because Def-II-X
doesn't have to wait Con1: Def already got X "next-key" lock that also
holds the gap before the record.

* Fix
Allow lock in `lock_rec_other_has_conflicting()` if there is already
non-waiting stronger or equal lock in this transaction
(`lock_rec_has_expl()`).

row_search_mvcc(): SELECT FOR UPDATE skips inserted records when
next-key lock is released. Fixed by stepping back before wait and
stepping forward before acquire: it steps into the gap again and
discovers newly inserted records. Note that change to row_sel() is not
required as it is used for internal queries only.

* Test fixes
innodb.auto_increment_dup: log-bin behaves like skip-log-bin because
of no bogus deadlock on UPDATE.

versioning.update: originally described deadlock from this task is now
disappeared.

MDEV-7098 spider/bg.spider_fixes failed in buildbot with safe_mutex: Trying to unlock mutex conn->mta_conn_mutex that wasn't locked at storage/spider/spd_db_conn.cc, line 671

build_template_field(): Initialize templ->rec_field_is_prefix
also for indexes on virtual columns. This was caught on 10.5 by
MemorySanitizer as use-of-uninitialized-value in
row_search_with_covering_prefix() when running the test
main.fast_prefix_index_fetch_innodb.

Add -Wno-missing-field-initializers for MyRocks and gcc version below 5.0

Passing a null pointer to a nonnull argument is not only undefined
behaviour, but it also grants the compiler the permission to optimize
away further checks whether the pointer is null. GCC -O2 at least
starting with version 8 may do that, potentially causing SIGSEGV.

These problems were caught in a WITH_UBSAN=ON build with the
Bug#7024 test in main.view.

Passing a null pointer to the "%s" argument of a printf-like
function is undefined behaviour. In the GNU libc implementation
of the printf() family of functions, it happens to work.

GCC 10.2.0 would diagnose this with -Wformat-overflow -Og.
In -fsanitize=undefined (WITH_UBSAN=ON) builds, a runtime error
would be generated. In some other builds, GCC 8 or later might infer
that the parameter is nonnull and optimize away further checks whether
the parameter is null, leading to SIGSEGV.

During insertion of clustered index, InnoDB does the check for foreign key
constraints. Problem is that it uses the clustered index entry to search
indexes of referenced tables and it could lead to unexpected result
when there is no foreign index.

Solution:
========
  Rebuild the tuple based on foreign column names before searching it
on reference index when there is no foreign index.

Backporting fixes for:

MDEV-22317: SIGSEGV in my_free/delete_dynamic in optimized builds (ARIA)
  Backported following commits from: 10.5.3
  commit 77e1b0c3 -- Post push fix.
  commit 2e6b21be

MDEV-22059: MSAN report at replicate_ignore_table_grant
  Backported following  commits from: 10.5.4
  commit 840fb495

Build failure was:
storage/innobase/os/os0proc.cc:144:3: error: use of undeclared identifier 'MEM_UNDEFINED'

                MEM_UNDEFINED(ptr, size);

Assumed to be introduced in MDEV-20377
commit: c36834c8

This also fixes MDEV-20464.

The InnoDB index fields store bytes, not characters.
Remove some unnecessary conversions from characters to bytes.

This also fixes MDEV-20422 and the wrong-result bug MDEV-12486.

Add a proper error handling of innobase_get_computed_value results in
row_upd_store_row/row_upd_store_v_row.

Also add an assertion in row_vers_build_clust_v_col to fail during row
purge.
Add one more assertion in row_sel_sec_rec_is_for_clust_rec for possible
future catches.

The problem was in improper error handling behavior in
`row_upd_build_difference_binary`:
`innobase_free_row_for_vcol` wasn't called.

To eliminate this problem in all potential places, a refactoring has been
made:
* class ib_vcol_row is added. It owns VCOL_STORAGE and heap and maintains
 it in RAII manner
* all innobase_allocate_row_for_vcol/innobase_free_row_for_vcol pairs are
 substituted
 with ib_vcol_row usage
* row_merge_buf_add is only left untouched because it doesn't own vheap
 passed as an argument
* innobase_allocate_row_for_vcol does not allocate VCOL_STORAGE anymore and
 accepts it as an argument -- this reduces a number of memory allocations
 * move rec_printer out of `#ifndef DBUG_OFF` and mark it cold

(This commit is exclusively for 10.1 branch, do not merge it to upper ones)

In case of a pattern of non-STMT_END-marked Rows-log-event (A) followed by
a STMT_END marked one (B) mysqlbinlog mixes up the base64 encoded rows events
with their pseudo sql representation produced by the verbose option:
      BINLOG '
        base64 encoded data for A
        ### verbose section for A
        base64 encoded data for B
        ### verbose section for B
      '/*!*/;
In effect the produced BINLOG '...' query is not valid and is rejected with the error.
Examples of this way malformed BINLOG could have been found in binlog_row_annotate.result
that gets corrected with the patch.

The issue is fixed with introduction an auxiliary IO_CACHE to hold on the verbose
comments until the terminal STMT_END event is found. The new cache is emptied
out after two pre-existing ones are done at that time.
The correctly produced output now for the above case is as the following:
      BINLOG '
        base64 encoded data for A
        base64 encoded data for B
      '/*!*/;
        ### verbose section for A
        ### verbose section for B

Thanks to Alexey Midenkov for the problem recognition and attempt to tackle,
Venkatesh Duggirala who produced a patch for the upstream whose
idea is exploited here, as well as to MDEV-23077 reporter LukeXwang who
also contributed a piece of a patch aiming at this issue.

Extra: mysqlbinlog_row_minimal refined to not produce mutable numeric values into the result file.

(This commit is exclusively for 10.2 branch. Do not merge it to 10.3)

In case of a pattern of non-STMT_END-marked Rows-log-event (A) followed by
a STMT_END marked one (B) mysqlbinlog mixes up the base64 encoded rows events
with their pseudo sql representation produced by the verbose option:
      BINLOG '
        base64 encoded data for A
        ### verbose section for A
        base64 encoded data for B
        ### verbose section for B
      '/*!*/;
In effect the produced BINLOG '...' query is not valid and is rejected with the error.
Examples of this way malformed BINLOG could have been found in binlog_row_annotate.result
that gets corrected with the patch.

The issue is fixed with introduction an auxiliary IO_CACHE to hold on the verbose
comments until the terminal STMT_END event is found. The new cache is emptied
out after two pre-existing ones are done at that time.
The correctly produced output now for the above case is as the following:
      BINLOG '
        base64 encoded data for A
        base64 encoded data for B
      '/*!*/;
        ### verbose section for A
        ### verbose section for B

Thanks to Alexey Midenkov for the problem recognition and attempt to tackle,
and to Venkatesh Duggirala who produced a patch for the upstream whose
idea is exploited here, as well as to MDEV-23077 reporter LukeXwang who
also contributed a piece of a patch aiming at this issue.

FAILED: sql/CMakeFiles/sql.dir/sql_test.cc.o
/home/kevgs/bin/clang++ -DHAVE_CONFIG_H -DHAVE_EVENT_SCHEDULER -DHAVE_POOL_OF_THREADS -DMYSQL_SERVER -D_FILE_OFFSET_BITS=64 -Iinclude -I../include -I../sql -Ipcre -I../pcre -I../zlib -Izlib -I../extra/yassl/include -I../extra/yassl/taocrypt/include -Isql -I../wsrep -O2 -fdiagnostics-color=always -fno-omit-frame-pointer -gsplit-dwarf -march=native -mtune=native -fPIC -fno-rtti -g -DENABLED_DEBUG_SYNC -ggdb3 -DSAFE_MUTEX -Wall -Wdeclaration-after-statement -Wextra -Wformat-security -Wno-init-self -Wno-null-conversion -Wno-unused-parameter -Wno-unused-private-field -Woverloaded-virtual -Wvla -Wwrite-strings -Werror   -DHAVE_YASSL -DYASSL_PREFIX -DHAVE_OPENSSL -DMULTI_THREADED -MD -MT sql/CMakeFiles/sql.dir/sql_test.cc.o -MF sql/CMakeFiles/sql.dir/sql_test.cc.o.d -o sql/CMakeFiles/sql.dir/sql_test.cc.o -c ../sql/sql_test.cc
../sql/sql_test.cc:390:20: error: '::' and '*' tokens forming pointer to member type are separated by whitespace [-Werror,-Wcompound-token-split-by-space]
Item* (List<Item>:: *dbug_list_item_elem_ptr)(int)= &List<Item>::elem;
                 ~~^~
../sql/sql_test.cc:391:32: error: '::' and '*' tokens forming pointer to member type are separated by whitespace [-Werror,-Wcompound-token-split-by-space]
Item_equal* (List<Item_equal>:: *dbug_list_item_equal_elem_ptr)(int)=
                             ~~^~
../sql/sql_test.cc:393:32: error: '::' and '*' tokens forming pointer to member type are separated by whitespace [-Werror,-Wcompound-token-split-by-space]
TABLE_LIST* (List<TABLE_LIST>:: *dbug_list_table_list_elem_ptr)(int) =
                             ~~^~
3 errors generated.

While doing TOI buffer OR REPLACE option was not added to replicated
string.

This commit contains a fix and extended test case for a ASAN failure
reported during galera.fk mtr testing.
The reported heap buffer overflow happens in test case where a cascading
foreign key constraint is defined for a column of varchar type, and
galera.fk.test has such vulnerable test scenario.

Troubleshoting revealed that erlier fix for MDEV-19660 has made a fix
for cascading delete handling to append wsrep keys from pcur->old_rec,
in row_ins_foreign_check_on_constraint(). And, the ASAN failuer comes from
later scanning of this old_rec reference.

The fix in this commit, moves the call for wsrep_append_foreign_key() to happen
somewhat earlier, and inside ongoing mtr, and using clust_rec which is set
earlier in the same mtr for both update and delete cascade operations.
for wsrep key populating, it does not matter when the keys are populated,
all keys just have to be appended before wsrep transaction replicates.

Note that I also tried similar fix for earlier wsrep key append, but using
the old implementation with pcur->old_rec (instead of clust_rec), and same
ASAN failure was reported. So it appears that pcur->old_rec is not properly
set, to be used for wsrep key appending.

galera.galera_fk_cascade_delete test has been extended by two new test scenarios:
* FK cascade on varchar column.
  This test case reproduces same scenario as galera.fk, and this test scenario
  will also trigger ASAN failure with non fixed MariaDB versions.
* multi-master conflict with FK cascading.
  this scenario causes a conflict between a replicated FK cascading transaction
  and local transaction trying to modify the cascaded child table row.
  Local transaction should be aborted and get deadlock error.
  This test scenario is passing both with old MariaDB version and with this
  commit as well.

The issue here was that the query was using ORDER BY LIMIT optimzation where
the access method was changed from EQ_REF access to an index scan (index that would
resolve the ORDER BY clause).
But the parameter READ_RECORD::unlock_row was not reset to rr_unlock_row, which is
used when the access method is not EQ_REF access.

MDEV-23587 : galera_3nodes.galera_var_dirty_reads2 MTR failed: 1047: WSREP has not yet prepared node for application use

Add wait_condition to make sure insert has been replicated
and after cluster restore wait until node is ready before
continuing.

MDEV-23580 : galera_3nodes.galera_ipv6_rsync_section MTR failed: WSREP_SST: [ERROR] rsync daemon port '16008' has been taken

Add force_restart to free rsync daemon port.

MDEV-23581 : galera_3nodes.galera_ipv6_rsync MTR failed: WSREP_SST: [ERROR] rsync daemon port '16008' has been taken

Add force_restart to free rsync daemon port.

MDEV-23576 : galera_3nodes.galera_ipv6_mysqldump MTR failed: WSREP_SST: [ERROR] rsync daemon port '16008' has been taken

Add force_restart to clean up rsync daemon port.

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

Fix the include and add force_restart to stabilize.

MDEV-23573 : galera_3nodes.galera_ipv6_mariabackup MTR failed: Could not open '../galera/include/have_mariabackup.inc

Fix the include and add force_restart to stabilize.

for internal temporary tables: don't use realpath(),
and let them overwrite whatever orphan temp files might've
left in the tmpdir (see main.error_simulation test).

for user created temporary tables: we have to use realpath(),
(see 3a726ab6, remember DATA/INDEX DIRECTORY). don't allow
them to overwrite existing files.

This bug was reported by RACK911 LABS

This bug was originally repeated on 10.4 after defining a UNIQUE KEY
on a TEXT column, which is implemented by MDEV-371 by creating the
index on a hidden virtual column.

While row_vers_vc_matches_cluster() is executing in a purge thread
to find out if an index entry may be removed in a secondary index
that comprises a virtual column, another purge thread may process
the undo log record that this check is interested in, and write
a null BLOB pointer in that record. This would trip the assertion.

To prevent this from occurring, we must propagate the 'missing BLOB'
error up the call stack.

row_upd_ext_fetch(): Return NULL when the error occurs.

row_upd_index_replace_new_col_val(): Return whether the previous
version was built successfully.

row_upd_index_replace_new_col_vals_index_pos(): Check the error
result. Yes, we would intentionally crash on this error if it
occurs outside the purge thread.

row_upd_index_replace_new_col_vals(): Check for the error condition,
and simplify the logic.

trx_undo_prev_version_build(): Check for the error condition.

Revert change to MDL and set SST donor thread as a system thread.
Joiner thread was already a system thread.

Sys_var_bit::session_save_default() ignored reverse_semantics property.