MemorySanitizer (clang -fsanitize=memory) requires that all code
be compiled with instrumentation enabled. The C runtime library
is an exception. Failure to use instrumented libraries will cause
bogus messages about memory being uninitialized.

In WITH_MSAN builds, we must avoid calling getservbyname(),
because even though it is a standard library function, it is
not instrumented, not even in clang 10.

The following cmake options were tested:

-DCMAKE_C_FLAGS='-march=native -O2'
-DCMAKE_CXX_FLAGS='-stdlib=libc++ -march=native -O2'
-DWITH_EMBEDDED_SERVER=OFF -DWITH_UNIT_TESTS=OFF -DCMAKE_BUILD_TYPE=Debug
-DWITH_INNODB_{BZIP2,LZ4,LZMA,LZO,SNAPPY}=OFF
-DPLUGIN_{ARCHIVE,TOKUDB,MROONGA,OQGRAPH,ROCKSDB,CONNECT,SPIDER}=NO
-DWITH_SAFEMALLOC=OFF
-DWITH_{ZLIB,SSL,PCRE}=bundled
-DHAVE_LIBAIO_H=0
-DWITH_MSAN=ON

MEM_MAKE_DEFINED(): An alias for VALGRIND_MAKE_MEM_DEFINED()
and in the future, __msan_unpoison().

For now, neither MEM_MAKE_DEFINED() nor MEM_UNDEFINED()
perform any action under MSAN. Enabling them will catch more bugs, but
will also require some more fixes or work-arounds.

Json_writer::add_double(): Work around a frequently occurring
failure in optimizer tests, related to EXPLAIN FORMAT=JSON.

dtoa(): Disable MSAN altogether. For some reason, this function
is triggering a lot of trouble, especially when invoked for
DBUG functions. The MDL default timeout is dd=86400 seconds,
and for some reason it is claimed to be uninitialized.

InnoDB: Define UNIV_DEBUG_VALGRIND also WITH_MSAN.

ut_crc32_8_hw(), ut_crc32_64_low_hw(): Use the compiler built-in
functions instead of inline assembler when building WITH_MSAN.
This will require at least -msse4.2 when building for IA-32 or AMD64.
The inline assembler would not be instrumented, and would thus cause
bogus failures.

Valgrind only seems to complain about memcmp() operations that
actually end up reading uninitialized data, while MemorySanitizer
requires that the entire length of both buffers be defined.

Rework stats a bit, so we're not missing any queue_get() now.

Don't do stats_reset_table(), if generic threadpool is off.

During the test main.query_cache_innodb, only 16 bytes of
db_buf are initialized during the memcmp() in
dict_acquire_mdl_shared<false>(), but db_len was wrongly set to 20 bytes.

Something similar was fixed in MDEV-21344, but only for the table name,
in commit 0e25a8b4.

dict_table_t::parse_name(): Assign the return value of
filename_to_tablename() to the output parameters for lengths.
There is no need to invoke strlen().

With OpenSSL < 1.1 there is a potential for a race condition to occur.
This can cause the S3 engine to crash. The workaround is to add locking
callbacks to OpenSSL so that this doesn't happen.

https://curl.haxx.se/libcurl/c/threadsafe.html

There is a fix in libMariaS3 for this which when a certain flag is set
(HAVE_CURL_OPENSSL_UNSAFE) will add the required locks.

This patch adds CMake support so that the flag is set if it is found
that Curl is compiled with an unsafe OpenSSL version. For example Ubuntu
16.04 with libcurl4-openssl-dev.

- Updated icp_tests.inc and result files
- Updates usage of records_in_range() protype in cassandra

page_cur_insert_rec_low(): Remove a bogus condition that wrongly
omitted redo logging when the record contains no data payload bytes.
We can have such records in secondary indexes, when the values of
the PRIMARY KEY column(s) are the empty string, and the values of
secondary key column(s) are are NULL or the empty string.

page_apply_delete_dynamic(): Improve the consistency check, and
do not allow adjacent records to be less than 5 bytes apart from
each other. The fixed-size part of the record header is 5 bytes.
Usually there must also be some header or payload bytes, but in
an extreme case where all columns are CHAR(0) NOT NULL, the
minimum secondary index record size is 5 bytes, and the table can
contain at most 1 row. The minimum clustered index record size is
5+6+7 bytes (header, DB_TRX_ID, DB_ROLL_PTR) or x+5+4 bytes
(fixed-size header, child page number, and some additional header
or payload bytes).

- multi_range_read_info_const now uses the new records_in_range interface
- Added handler::avg_io_cost()
- Don't calculate avg_io_cost() in get_sweep_read_cost if avg_io_cost is
  not 1.0.  In this case we trust the avg_io_cost() from the handler.
- Changed test_quick_select to use TIME_FOR_COMPARE instead of
  TIME_FOR_COMPARE_IDX to align this with the rest of the code.
- Fixed bug when using test_if_cheaper_ordering where we didn't use
  keyread if index was changed
- Fixed a bug where we didn't use index only read when using order-by-index
- Added keyread_time() to HEAP.
  The default keyread_time() was optimized for blocks and not suitable for
  HEAP. The effect was the HEAP prefered table scans over ranges for btree
  indexes.
- Fixed get_sweep_read_cost() for HEAP tables
- Ensure that range and ref have same cost for simple ranges
  Added a small cost (MULTI_RANGE_READ_SETUP_COST) to ranges to ensure
  we favior ref for range for simple queries.
- Fixed that matching_candidates_in_table() uses same number of records
  as the rest of the optimizer
- Added avg_io_cost() to JT_EQ_REF cost. This helps calculate the cost for
  HEAP and temporary tables better. A few tests changed because of this.
- heap::read_time() and heap::keyread_time() adjusted to not add +1.
  This was to ensure that handler::keyread_time() doesn't give
  higher cost for heap tables than for normal tables. One effect of
  this is that heap and derived tables stored in heap will prefer
  key access as this is now regarded as cheap.
- Changed cost for index read in sql_select.cc to match
  multi_range_read_info_const(). All index cost calculation is now
  done trough one function.
- 'ref' will now use quick_cost for keys if it exists. This is done
  so that for '=' ranges, 'ref' is prefered over 'range'.
- scan_time() now takes avg_io_costs() into account
- get_delayed_table_estimates() uses block_size and avg_io_cost()
- Removed default argument to test_if_order_by_key(); simplifies code

Fixed by moving testing of get_best_group_min_max() after range testing.

Prototype change:
-  virtual ha_rows records_in_range(uint inx, key_range *min_key,
-                                   key_range *max_key)
+  virtual ha_rows records_in_range(uint inx, const key_range *min_key,
+                                   const key_range *max_key,
+                                   page_range *res)

The handler can ignore the page_range parameter. In the case the handler
updates the parameter, the optimizer can deduce the following:
- If previous range's last key is on the same block as next range's first
  key
- If the current key range is in one block
- We can also assume that the first and last block read are cached!
  This can be used for a better calculation of IO seeks when we
  estimate the cost of a range index scan.

The parameter is fully implemented for MyISAM, Aria and InnoDB.
A separate patch will update handler::multi_range_read_info_const() to
take the benefits of this change and also remove the double
records_in_range() calls that are not anymore needed.

One may access freed THD members after LOCK_thd_kill is released.

With original code it can happen when killing wsrep-disabled thread on a
wsrep-enabled server. With 91ab42a8 it is happening on a wsrep-disabled
server.

Otherwise fall back to libcurl3

page_cur_insert_rec_low(): Check the array bounds before comparing.
We used to read one byte beyond the end of the 'rec' payload.
The incorrect logic was originally introduced in
commit 7ae21b18
and modified in commit 138cbec5.

Backport to 10.4:

- Don't try to push down SELECTs that have a side effect

- In case the storage engine did support pushdown of SELECT with an INTO
  clause, write the rows we've got from it into select->join->result,
  and not thd->protocol.  This way, SELECT ... INTO ... FROM
  smart_engine_table will put the result into where instructed, and
  NOT send it to the client.

main.mysql_upgrade_noengine did not do "FLUSH PRIVILEGES" after restoring
the original backed global_priv table. So following tests might fail on
lack of some privileges.

Adding the FLUSH PRIVILEGES statement.

Also allocate inuse_relaylog with new rather than my_malloc(MY_ZEROFILL).

A desperate attempt to workaround MemorySanitizer deficiencies.

Fix clang-cl built

The cause was an uninitalized variable on the slave when reading a dummy
event that can only be generated by the test.

Fixed by ensuring that flag2 is always initialized.
Fixed also some indentation issues and improved comments.

by suppressing Unix only system checks

The test main.mysqltest could crash or hang with
cmake -DWITH_ASAN=ON builds. The reason appears to be
a memory leak, which was found out by manually invoking

echo --replace_regex a > file
ASAN_OPTIONS=log_path=/dev/shm/asan mysqltest ... < file

and then examining the /dev/shm/asan.* file.

commit 121a5e8d revised the function
buf_pool_watch_unset() in such a way that the debug field
buf_page_t::in_page_hash is no longer protected by buf_pool.mutex
and thus not safe to access by the debug assertion in
buf_pool_watch_set().

For now, let us revert the change to buf_pool_watch_unset()
and have it acquire the buf_pool.mutex for a longer time.

MDEV-22030 Don't grant REPLICATION MASTER ADMIN automatically on upgrade from an older JSON user table

Adding a test to check that having a user with REPLICATION SLAVE
privilege is enough to run replication.

Made by Serg.

This was done to both simplify the code and also to be easier to handle
storage engines that are clustered on some other index than the primary
key.

As pk_is_clustering_key() and is_clustering_key now are using only
index_flags, these where removed from all storage engines.

Changes:
- Initalize Aria early to allow it to load mysql.plugin table with --help
- Don't print 'aborting' when doing --help
- Don't write 'loose' error messages on log_warning < 2 (2 is default)
- Don't write warnings about disabled plugings when doing --help
- Don't write aria_log_control or aria log files when doing --help
- When using --help, open all Aria tables in read only mode (safety)
- If aria_init() fails, do a cleanup(). (Frees used memory)
- If aria_log_control is locked with --help, then don't wait 30 seconds
  but instead return at once without initialzing Aria plugin.