Bug#57820 extractvalue crashes

Problem: ExtractValue and Replace crashed in some cases
due to invalid handling of empty and NULL arguments.

Per file comments:

  @mysql-test/r/ctype_ujis.result
  @mysql-test/r/xml.result
  @mysql-test/t/ctype_ujis.test
  @mysql-test/t/xml.test
  Adding tests

  @sql/item_strfunc.cc
  Make sure Item_func_replace::val_str safely handles empty strings.

  @sql/item_xmlfunc.cc
  set null_value if nodeset_func returned NULL,
  which is possible when the second argument is an
  unset user variable.

Fixing DoS regression problem.

Using "key_part->fieldnr - 1" to access the desired field
is only correct in real INSERT queries.
In case of inserting records into a temporary table
when performing GROUP BY queries this expression does not work.

Fix: Instead of accessing field_length and comparing it
to key_part->length, there is an easier way to check if
we're dealing with a prefix key: check key_part_flag against
HA_PART_KEY_SEG flag.

backport from 5.1

Problem: a flaw (derefencing a NULL pointer) in the LIKE optimization
code may lead to a server crash in some rare cases.

Fix: check the pointer before its dereferencing.

MySQL officially supports DATE values starting from 1000-01-01. This is
enforced for int values, but not for string values, thus one
could easily insert '0001-01-01' value. Int values are checked by
number_to_datetime function and Item_cache_datetime::val_str uses it
to fill MYSQL_TIME struct out of cached int value. This leads to the
scenario where Item_cache_datetime caches a non-null datetime value and when
it tries to convert it from int to string number_to_datetime function
treats the value as out-of-range and returns an error and
Item_cache_datetime::val_str returns NULL for a non-null value. Due to this
inconsistency server crashes.

Now number_to_datetime allows DATE values below 1000-01-01 if the
TIME_FUZZY_DATE flag is set. Better NULL handling for Item_cache_datetime.
Added the Item_cache_datetime::store function to reset str_value_cached flag
when an item is stored.

This crash could happen if SHOW CREATE VIEW indirectly failed to open a
view due to failures to open underlying tables (or functions). Several
such errors were hidden and converted to ER_VIEW_INVALID warnings to
prevent exposing details of underlying tables for which the user have
no privileges.

However, with the changes introduced by the patch for Bug#52044,
failing to open a view will cause opened tables, views and functions
to be closed. Since the errors causing these failures were converted
to warnings, SHOW CREATE VIEW would try to continue. This made it
possible to try to access memory that had been freed, causing a crash.

This patch fixes the problem by not closing opened tables, views and
functions in these cases. This allows SHOW CREATE VIEW to continue
and also prevents it from accessing freed memory.

Test case added to lock_sync.test.

This crash could happen if TRUNCATE TABLE indirectly failed to open a
merge table due to failures to open underlying tables. Even if opening
failed, the TRUNCATE TABLE code would try to invalidate the table in
the query cache. Since this table had been closed and memory released,
this could lead to a crash.

This bug was introduced by a combination of the changes introduced by
the patch for Bug#52044, where failing to open a table will cause opened
tables to be closed. And the changes in patch for Bug#49938, where
TRUNCATE TABLE uses the standard open tables function.

This patch fixes the problem by setting the TABLE pointer to NULL before 
invalidating the query cache.

Test case added to truncate_coverage.test.

Lines below which were added in the patch for Bug#56814 cause this crash:

+      if (table->table)
+        table->table->maybe_null= FALSE;

Consider following test case:
--
CREATE TABLE t1(f1 INT NOT NULL);
INSERT INTO t1 VALUES (16777214),(0);

SELECT COUNT(*) FROM t1 LEFT JOIN t1 t2
ON 1 WHERE t2.f1 > 1 GROUP BY t2.f1;

DROP TABLE t1;
--

We set TABLE::maybe_null to FALSE for t2 table
and in create_tmp_field() we create appropriate tmp table field
using create_tmp_field_from_item() function instead of
create_tmp_field_from_field. As a result we have
LONGLONG field. As we have GROUP BY clause we calculate
group buffer length, see calc_group_buffer().
Item from group list which is used for calculation
refer to the field from real tables and have LONG type.
So group buffer length become insufficient for storing of
LONGLONG value. It leads to overwriting of wrong memory
area in do_field_int() function which is called from
end_update().
After some investigation I found out that
create_tmp_field_from_item() is used only for OLAP
grouping and can not be used for common grouping
as it could be an incompatibility between tmp
table fields and group buffer length.
We can not remove create_tmp_field_from_item() call from
create_tmp_field as OLAP needs it and we can not use this
function for common grouping. So we should remove setting
TABLE::maybe_null to FALSE from simplify_joins().
In this case we'll get wrong behaviour of
list_contains_unique_index() back. To fix it we
could use Field::real_maybe_null() check instead of
Field::maybe_null() and add addition check of
TABLE_LIST::outer_join.

The problem is caused by bug49487 fix and became visible
after after bug56679 fix.
Items are cleaned up and set to unfixed state after filling derived table.
So we can not rely on item::fixed state in Item_func_group_concat::print
and we can not use 'args' array as items there may be cleaned up.
The fix is always to use orig_args array of items as it
always should contain the correct data.

On Windows, the parameter for number of bytes passed into WriteFile()
and ReadFile() is DWORD. Casting is needed to silence the warning on
64-bit Windows.

Also, adding several asserts to ensure the variable for number of bytes
is no more than 32 bits, even on 64-bit Windows.

This is for InnoDB Plugin.

rb://415
Approved by: Inaam

On Windows, the parameter for number of bytes passed into WriteFile()
and ReadFile() is DWORD. Casting is needed to silence the warning on
64-bit Windows.

Also, adding several asserts to ensure the variable for number of bytes
is no more than 32 bits, even on 64-bit Windows.

This is for built-in InnoDB.

rb://415
Approved by: Inaam

Fixed few typos and added better wording as suggested.

/export/home/pb2/build/sb_0-2459340-1288264809.63/mysql-5.5.8-ga/storage/innobase/os/os0sync.c: In function 'os_cond_wait_timed':
/export/home/pb2/build/sb_0-2459340-1288264809.63/mysql-5.5.8-ga/storage/innobase/os/os0sync.c:184: warning: format '%lu' expects type 'long unsigned int', but argument 4 has type 'time_t'
gmake[2]: *** [storage/innobase/CMakeFiles/innobase.dir/os/os0sync.c.o] Error 1 

On Windows, the parameter for number of bytes passed into WriteFile()
and ReadFile() is DWORD. Casting is needed to silence the warning on
64-bit Windows.

Also, adding several asserts to ensure the variable for number of bytes
is no more than 32 bits, even on 64-bit Windows.

rb://415
Approved by: Inaam