The assert inside String::copy() prevents copying from from "str"
if its own String::Ptr also points to the same memory.

The idea of the assert is that copy() performs memory reallocation,
and this reallocation can free (and thus invalidate) the memory pointed by Ptr,
which can lead to further copying from a freed memory.

The assert was incomplete: copy() can free the memory pointed by its Ptr
only if String::alloced is true!

If the String is not alloced, it is still safe to copy even from
the location pointed by Ptr.

This scenario demonstrates a safe copy():
  const char *tmp= "123";
  String str1(tmp, 3);
  String str2(tmp, 3);
  // This statement is safe:
  str2.copy(str1->ptr(), str1->length(), str1->charset(), cs_to, &errors);

Inside the copy() the parameter "str" is equal to String::Ptr in this example.
But it's still ok to reallocate the memory for str2, because str2
was a constant before the copy() call. Thus reallocation does not
make the memory pointed by str1->ptr() invalid.

Adjusting the assert condition to allow copying for constant strings.

Take into account client capabilities.

Sometimes, although not often, it would timeout after 3 minutes.

Happens with Innodb engine.

Move unlock_locked_table() past drop_open_table(), and
rollback current statement, so that we can actually unlock the table.

Anything else results in assertions, in drop, or unlock, or in close_table.

MDEV-25702(commit 696de6d0) should've
closed the fts table further. This patch closes the table after
finishing the bulk insert operation.

DBUG_ASSERT removed as the AUTO INCREMENT can actually be 0 when the
SET insert_id= 0; was done.

Get rid of the global big_buffer.

SysTablespace::file_not_found(): If the system tablespace cannot be
found and innodb_force_recovery has been specified, refuse to start up.
The system tablespace is necessary for accessing any InnoDB tables,
because it contains the TRX_SYS page (the state of transactions)
and the InnoDB data dictionary.

This is similar to our handling of innodb_read_only except that
we will happily create the InnoDB temporary tablespace even if
innodb_force_recovry is set.

MDEV-19129: Xcode compatibility update: mysql-test-run.pl: rename $opt_vs_config to $multiconfig to use with other cmake multiconfig generators

Based on mysql/mysql-server@bc9c46bf2894673d0df17cd0ee872d0d99663121
but without sleeps.

The test was verified to hit the debug assertion if the change to
fts_add_doc_by_id() in commit 2d98b967
was reverted.

fts_cache_t::total_size_at_sync: New field, to sample total_size.

fts_add_doc_by_id(): Invoke sync if total_size has grown too much
since the previous sync request. (Maintain cache->total_size_at_sync.)

ib_wqueue_t::length: Caches ib_list_len(*items).

ib_wqueue_len(): Removed. We will refer to fts_optimize_wq->length
directly.

Based on mysql/mysql-server@bc9c46bf2894673d0df17cd0ee872d0d99663121

trx_commit_in_memory(): Do not release the rseg reference before
trx_undo_commit_cleanup() has been invoked and the current transaction
is truly done with the rollback segment. The purpose of the reference
count is to prevent data races with trx_purge_truncate_history().

This is based on
mysql/mysql-server@ac79aa1522f33e6eb912133a81fa2614db764c9c.

InnoDB commit fails when consecutive FTS_DOC_ID value
is greater than 4294967295.
Fix is that InnoDB should remove the delta FTS_DOC_ID
value limitations and fts should encode 8 byte value,
remove FTS_DOC_ID_MAX_STEP variable. Replaced the
fts0vlc.ic file with fts0vlc.h

fts_encode_int(): Should be able to encode 10 bytes value

fts_get_encoded_len(): Should get the length of the value
which has 10 bytes

fts_decode_vlc(): Add debug assertion to verify the maximum
length allowed is 10.

mach_read_uint64_little_endian(): Reads 64 bit stored in
little endian format

Added a unit test case which check for minimum and maximum
value to do the fts encoding

In commit 1811fd51 the assertion
should have said error_reported instead of !error_reported.
But, that revised assertion would still fail in main.defaults
where ER_BAD_DATA is reported during CREATE TABLE.

create_table_info_t::innobase_table_flags(): Refuse to create
a PAGE_COMPRESSED table with PAGE_COMPRESSION_LEVEL=0 if also
innodb_compression_level=0.

The parameter value innodb_compression_level=0 was only somewhat
meaningful for testing or debugging ROW_FORMAT=COMPRESSED tables.
For the page_compressed format, it never made any sense, and the
check in dict_tf_is_valid_not_redundant() that was added in
72378a25 (MDEV-12873) would cause
the server to crash.

The assertion is absolutely correct since no data access is possible after
XA PREPARE.

The check is added in mysql_ha_read.

This is a duplicate of MDEV-18278 89936f11, but I will add an
additional assertion

Description:

The frm corruption should not be reported during CREATE TABLE. Normally
it doesn't, and the data to fill TABLE is taken by open_table_from_share
call. However, the vcol data is stored as SQL string in
table->s->vcol_defs.str and is anyway parsed on each table open.
It is impossible [or hard] to avoid, because it's hard to clone the
expression tree in general (it's easier to parse).

Normally parse_vcol_defs should only fail on semantic errors. If so,
error_reported is set to true. Any other failure is not expected during
table creation. There is either unhandled/unacknowledged error, or
something went really wrong, like memory reject. This all should be
asserted anyway.

Solution:
* Set *error_reported=true for the forward references check;
* Assert for every unacknowledged error during table creation.

We should set the charset in
Item_func_json_format::fix_length_and_dec().

Let us use a minimal-size buffer pool to ensure that page flushing
will be slow enough so that LRU eviction cannot be avoided.

Do not print illegal table field names for non-top-level SELECT list,
they will not be refered in any case but create problem for parsing
of printed result.

Problem:
========
This patch addresses two issues.

First, if a CHANGE MASTER command is issued and an error happens
while locating the replica’s relay logs, the logs can be put into an
invalid state where future updates fail and future CHANGE MASTER
calls crash the server. More specifically, right before a replica
purges the relay logs (part of the `CHANGE MASTER TO` logic), the
relay log is temporarily closed with state LOG_TO_BE_OPENED. If the
server errors in-between the temporary log closure and purge, i.e.
during the function find_log_pos, the log should be closed.
MDEV-25284 reveals the log is not properly closed.

Second, upon issuing a RESET SLAVE ALL command, a slave’s GTID
filters are not cleared (DO_DOMAIN_IDS, IGNORE_DOMIAN_IDS,
IGNORE_SERVER_IDS). MySQL had a similar bug report, Bug #18816897,
which fixed this issue to clear IGNORE_SERVER_IDS after issuing
RESET SLAVE ALL in version 5.7.

Solution:
=========

To fix the first problem, the CHANGE MASTER error handling logic was
extended to transition the relay log state to LOG_CLOSED from
LOG_TO_BE_OPENED.

To fix the second problem, the RESET SLAVE ALL logic is extended to
clear the domain_id filter and ignore_server_ids.

Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>

Schema and table names in a veiw FRM files are:
- in upper case on Linux
- in lower case on Windows

Using the LOWER() function when displaying an FRM file fragment,
to avoid the OS-specific difference.

This happens upon CREATE USER and DROP ROLE.

The underlying problem is that our HASH implementation shuffles elements
around when performing an update or delete. This means that when doing a
scan through the HASH table by index, in search of elements to delete or
update one must restart the scan to make sure nothing is missed if at least
one delete / update happened.

More specifically, what happened in this case:
The hash has 131 element, DROP ROLE removes the element
[119]. Its [119]->next was element [129], so [129] is moved to [119].
Now we need to compact the hash, removing the last element [130]. It
gets one bit off its hash value and becomes element [2]. The existing
element [2] is moved to [129], and old [130] is moved to [2].

We cannot simply move [130] to [129] and make [2]->next=130, it won't
work if [2] is itself in the collision list and doesn't belong in [2].

The handle_grant_struct code assumed that it is safe to continue by only
reexamining the currently modified / deleted element index, but that is
not true.

Missing to delete an element in the hash triggered the assertion in
the test case. DROP ROLE would not clear all necessary role->role or
role->user mappings.

To fix the problem we ensure that the scan is restarted, only if an
element was deleted / updated, similar to how bubble-sort keeps sorting
until it finds no more elements to swap.

MDEV-23408 Wrong result upon query from I_S and further Assertion `!alias_arg || strlen(alias_arg->str) == alias_arg->length' failed with certain connection charset

There were two independent problems which lead to the crash
and to the non-relevant records returned in I_S queries:

- The code in the I_S implementation was not secure
  about values with 0x00 bytes.
  It's fixed by using check_db_name() and check_table_name()
  inside make_table_name_list(), and by adding the test for
  0x00 inside check_table_name().

- The code in Item_string::print() did not convert
  strings without introducers when restoring
  the CREATE VIEW statement from an Item tree.
  This made wrong literals inside the "query" line in the view FRM file
  in cases when the VIEW parse time
  character_set_client!=character_set_connection.
  That's fixed by adding a proper conversion.

  This change also fixed a similar problem in SHOW PROCEDURE CODE -
  the literals were displayed in wrong character set in SP instructions
  in cases when the SP parse time
  character_set_client!=character_set_connection.

but must do that at the end of the statement.
A provide template patch is elaborated also to match
to the upstream fixes of the very same bug.

Add wait_conditions to stabilize

In commit 1cb218c3 (MDEV-26450)
we introduced the function log_write_and_flush(), which may
compete with log_checkpoint() invoking log_write_flush_to_disk_low()
from another thread.

The assertion n_pending_flushes==1 is too strict.
There is no possibility of a race condition here, because
fil_flush() is protected by fil_system->mutex and the
rest will be protected by log_sys->mutex.

log_write_flush_to_disk_low(), log_write_and_flush():
Relax the assertions to test for a nonzero count.