Item_func_concat_ws::val_str():
- collects the result into the string "str" passed as a parameter.
- calls val_str(&tmp_buffer) to get arguments.
At some point due to heuristic it decides to swap the buffers:
- collect the result into &tmp_buffer
- call val_str(str) to get arguments
Item_func_password::val_str_ascii() returns a String pointing to its
member tmp_value[SCRAMBLED_PASSWORD_CHAR_LENGTH+1].
As a result, it's possible that both str and tmp_buffer in
Item_func_concat_ws::val_str() point to Item_func_password::tmp_value.
Then, memcmp() called on overlapping memory fragrments.
Fixing Item_func_password::val_str_ascii() to use Item::copy()
instead of Item::set().
Item_func_substr::fix_length_and_dec() incorrecltly calculated its max_length
to 0 when a huge number was passed as the third argument:
substring('hello', 1, 4294967295)
Fixing this.
The code in the can_eval_in_optimize() branch in
Item_func_pad::fix_length_and_dec() did not take into account
that the constant can be negative. So the function will return NULL.
This later crashed on DBUG_ASSERT() because a NOT NULL function returned NULL.
Adding set_maybe_null() into this branch if the constant is negative.
create templates
thd->alloc<X>(n) to use instead of (X*)thd->alloc(sizeof(X)*n)
and the same for thd->calloc(). By the default the type is char,
so old usage of thd->alloc(size) works too.
Item_func_insert::fix_length_and_dec() incorrectly calculated max_length
when its collation.collation evaluated to my_charset_bin.
Fixing the code to calculate max_length in terms of octets rather
than in terms of characters when collation.collation is my_charset_bin.
Step#1: fixing the return type of strnxfrm() from size_t to this structure:
typedef struct
{
size_t m_output_length;
size_t m_source_length_used;
uint m_warnings;
} my_strnxfrm_ret_t;
Search conditions were evaluated using val_int(), which was wrong.
Fixing the code to use val_bool() instead.
Details:
- Adding a new item_base_t::IS_COND flag which marks Items used
as <search condition> in WHERE, HAVING, JOIN ON, CASE WHEN clauses.
The flag is at the parse time.
These expressions must be evaluated using val_bool() rather than val_int().
Note, the optimizer creates more Items which are used as search conditions.
Most of these items are not marked with IS_COND yet. This is OK for now,
but eventually these Items can also be fixed to have the flag.
- Adding a method Item::is_cond() which tests if the Item has the IS_COND flag.
- Implementing Item_cache_bool. It evaluates the cached expression using
val_bool() rather than val_int().
Overriding Type_handler_bool::Item_get_cache() to create Item_cache_bool.
- Implementing Item::save_bool_in_field(). It uses val_bool() rather than
val_int() to evaluate the expression.
- Implementing Type_handler_bool::Item_save_in_field()
using Item::save_bool_in_field().
- Fixing all Item_bool_func descendants to implement a virtual val_bool()
rather than a virtual val_int().
- To find places where val_int() should be fixed to val_bool(), a few
DBUG_ASSERT(!is_cond()) where added into val_int() implementations
of selected (most frequent) classes:
Item_field
Item_str_func
Item_datefunc
Item_timefunc
Item_datetimefunc
Item_cache_bool
Item_bool_func
Item_func_hybrid_field_type
Item_basic_constant descendants
- Fixing all places where DBUG_ASSERT() happened during an "mtr" run
to use val_bool() instead of val_int().
Update `SESSION_USER()` behaviour to be comparable with `CURRENT_USER()`.
`SESSION_USER()` will return the user and host columns from `mysql.user`
used to authenticate the user when the session was created.
Historically `SESSION_USER()` was an alias of `USER()` function. The
main difference with `USER()` behaviour after this changes is that
`SESSION_USER()` now returns the host column from `mysql.user` instead of
the client host or ip.
NOTE: `SESSION_USER_IS_USER` old mode is added to make the change
backward compatible.
All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer
Amazon Web Services, Inc.
The commit cd5808eb introduced a union as a storage for the format
argument passed to the internal API fmt::detail::make_arg. This was done
to solve the issue that the internal API no longer accepted temporary
variables.
However, it's generally better to avoid using internal APIs, as they are
more likely to have breaking changes in the future. Instead, we can use
the public API fmt::dynamic_format_arg_store to dynamically build the
argument list. This API accepts temporary variables, and its behavior is
more stable than the internal API. `libfmt.cmake` is updated to reflect
the change as well.
All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer Amazon Web
Services, Inc.
Based on the current logic, objects of classes Item_func_charset and
Item_func_coercibility (responsible for CHARSET() and COERCIBILITY()
functions) are always considered constant.
However, SQL syntax allows their use in a non-constant manner, such as
CHARSET(t1.a), COERCIBILITY(t1.a).
In these cases, the `used_tables()` parameter corresponds to table names
in the function parameters, creating an inconsistency: the item is marked
as constant but accesses tables. This leads to crashes when
conditions with CHARSET()/COERCIBILITY() are pushed into derived tables.
This commit addresses the issue by setting `used_tables()` to 0 for
`Item_func_charset` and `Item_func_coercibility`. Additionally, the items
now store the return values during the preparation phase and return
them during the execution phase. This ensures that the items do not call
its arguments methods during the execution and are truly constant.
Reviewer: Alexander Barkov <bar@mariadb.com>
Fixing applying the COLLATE clause to a parameter caused an error error:
COLLATION '...' is not valid for CHARACTER SET 'binary'
Fix:
- Changing the collation derivation for a non-prepared Item_param
to DERIVATION_IGNORABLE.
- Allowing to apply any COLLATE clause to expressions with DERIVATION_IGNORABLE.
This includes:
1. A non-prepared Item_param
2. An explicit NULL
3. Expressions derived from #1 and #2
For example:
SELECT ? COLLATE utf8mb_unicode_ci;
SELECT NULL COLLATE utf8mb_unicode_ci;
SELECT CONCAT(?) COLLATE utf8mb_unicode_ci;
SELECT CONCAT(NULL) COLLATE utf8mb_unicode_ci
- Additional change: preserving the collation of an expression when
the expression gets assigned to a PS parameter and evaluates to SQL NULL.
Before this change, the collation of the parameter was erroneously set
to &my_charset_binary.
- Additional change: removing the multiplication to mbmaxlen from the
fix_char_length_ulonglong() argument, because the multiplication already
happens inside fix_char_length_ulonglong().
This fixes a too large column size created for a COLLATE clause.
Item_func_hex::fix_length_and_dec() evaluated a too short data type
for signed numeric arguments, which resulted in a 'Data too long for column'
error on CREATE..SELECT.
Fixing the code to take into account that a short negative
numer can produce a long HEX value: -1 -> 'FFFFFFFFFFFFFFFF'
Also fixing Item_func_hex::val_str_ascii_from_val_real().
Without this change, MTR test with HEX with negative float point arguments
failed on some platforms (aarch64, ppc64le, s390-x).
