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

a compile error with MSVC. The problem was introduced in Revision: 3150
revid:marko.makela@oracle.com-20100809085837-s1nfx6gjf7l6ttab

buf_pool_init(): Replace ut_ad(n_instances < MAX_BUFFER_POOLS)
with ut_ad(n_instances <= MAX_BUFFER_POOLS).
(Spotted by Michael Izioumtchenko.)
Add ut_ad(n_instances > 0).

The problem is dividing by const value when
the result is out of supported range.
The fix:
-return LONGLONG_MIN if the result is out of supported range for DIV operator.
-return 0 if divisor is -1 for MOD operator.

buf_page_t: Remove the buf_pool pointer. Add buf_pool_index:6 next to
buf_fix_count:19 (it was buf_fix_count:25). This will limit the number
of concurrent transactions to somewhere around 524,288.

buf_pool_index(buf_pool): A new function to determine the index of a
buffer pool in buf_pool_ptr[].

buf_pool_ptr: Make this a dynamically allocated array instead of an
array of pointers. Allocate the array in buf_pool_init() and free in
buf_pool_free().

buf_pool_free_instance(): No longer free the buf_pool object, as it is
allocated from a big array.

buf_pool_from_bpage(), buf_pool_from_block(): Move the definitions to
the beginning of the files, because some compilers have (had) problems
with forward definitions of inline functions. Calculate the buffer
pool from buf_pool_index.

buf_pool_from_array(): Add debug assertions for input validation.

CMakeLists.txt: Remove the checks for mysql_storage_engine.cmake
and MYSQL_VERSION_ID.

ha_innodb.cc, ha_innodb.h: Remove the checks for MYSQL_VERSION_ID.

  rb://498
  
  Fix handling of update_undo_logs at trx commit. Previously, when
  rseg->update_undo_list grows beyond 500 the update_undo_logs were
  marked with state TRX_UNDO_TO_FREE which should have been
  TRX_UNDO_TO_PURGE.
  In 5.5 we don't need the heuristic as we support multiple rollback
  segments.
  
  Approved by: Sunny Bains

rb://498

Fix handling of update_undo_logs at trx commit. Previously, when
rseg->update_undo_list grows beyond 500 the update_undo_logs were
marked with state TRX_UNDO_TO_FREE which should have been
TRX_UNDO_TO_PURGE.

Approved by: Sunny Bains