Fix regression introduced in MDEV-19893
Some errors must be sent with seqno = 0, e.g those that are detected
before server sends its first "welcome" packet (e.g too many connections)
This was not taken into account originally in MDEV-19893 fix.
We need to check sql_errno, before fixing sequence number, to see
if the error we send is really an out-of-bound, e.g a KILL.
The assertion failed in handler::ha_reset upon SELECT under
READ UNCOMMITTED from table with index on virtual column.
This was the debug-only failure, though the problem is mush wider:
* MY_BITMAP is a structure containing my_bitmap_map, the latter is a raw
bitmap.
* read_set, write_set and vcol_set of TABLE are the pointers to MY_BITMAP
* The rest of MY_BITMAPs are stored in TABLE and TABLE_SHARE
* The pointers to the stored MY_BITMAPs, like orig_read_set etc, and
sometimes all_set and tmp_set, are assigned to the pointers.
* Sometimes tmp_use_all_columns is used to substitute the raw bitmap
directly with all_set.bitmap
* Sometimes even bitmaps are directly modified, like in
TABLE::update_virtual_field(): bitmap_clear_all(&tmp_set) is called.
The last three bullets in the list, when used together (which is mostly
always) make the program flow cumbersome and impossible to follow,
notwithstanding the errors they cause, like this MDEV-17556, where tmp_set
pointer was assigned to read_set, write_set and vcol_set, then its bitmap
was substituted with all_set.bitmap by dbug_tmp_use_all_columns() call,
and then bitmap_clear_all(&tmp_set) was applied to all this.
To untangle this knot, the rule should be applied:
* Never substitute bitmaps! This patch is about this.
orig_*, all_set bitmaps are never substituted already.
This patch changes the following function prototypes:
* tmp_use_all_columns, dbug_tmp_use_all_columns
to accept MY_BITMAP** and to return MY_BITMAP * instead of my_bitmap_map*
* tmp_restore_column_map, dbug_tmp_restore_column_maps to accept
MY_BITMAP* instead of my_bitmap_map*
These functions now will substitute read_set/write_set/vcol_set directly,
and won't touch underlying bitmaps.
The assertion failed in handler::ha_reset upon SELECT under
READ UNCOMMITTED from table with index on virtual column.
This was the debug-only failure, though the problem is mush wider:
* MY_BITMAP is a structure containing my_bitmap_map, the latter is a raw
bitmap.
* read_set, write_set and vcol_set of TABLE are the pointers to MY_BITMAP
* The rest of MY_BITMAPs are stored in TABLE and TABLE_SHARE
* The pointers to the stored MY_BITMAPs, like orig_read_set etc, and
sometimes all_set and tmp_set, are assigned to the pointers.
* Sometimes tmp_use_all_columns is used to substitute the raw bitmap
directly with all_set.bitmap
* Sometimes even bitmaps are directly modified, like in
TABLE::update_virtual_field(): bitmap_clear_all(&tmp_set) is called.
The last three bullets in the list, when used together (which is mostly
always) make the program flow cumbersome and impossible to follow,
notwithstanding the errors they cause, like this MDEV-17556, where tmp_set
pointer was assigned to read_set, write_set and vcol_set, then its bitmap
was substituted with all_set.bitmap by dbug_tmp_use_all_columns() call,
and then bitmap_clear_all(&tmp_set) was applied to all this.
To untangle this knot, the rule should be applied:
* Never substitute bitmaps! This patch is about this.
orig_*, all_set bitmaps are never substituted already.
This patch changes the following function prototypes:
* tmp_use_all_columns, dbug_tmp_use_all_columns
to accept MY_BITMAP** and to return MY_BITMAP * instead of my_bitmap_map*
* tmp_restore_column_map, dbug_tmp_restore_column_maps to accept
MY_BITMAP* instead of my_bitmap_map*
These functions now will substitute read_set/write_set/vcol_set directly,
and won't touch underlying bitmaps.
Passing a null pointer to a nonnull argument is not only undefined
behaviour, but it also grants the compiler the permission to optimize
away further checks whether the pointer is null. GCC -O2 at least
starting with version 8 may do that, potentially causing SIGSEGV.
The problem happened because Item_ident_for_show did not implement val_native().
Solution:
- Removing class Item_ident_for_show
- Implementing a new method Protocol::send_list_fields() instead,
which accepts a List<Field> instead of List<Item> as input.
Now no any Item creation is done during mysqld_list_fields().
Adding helper methods, to reuse the code easier:
- Moved a part of Protocol::send_result_set_metadata(),
responsible for sending an individual field metadata,
into a new method Protocol_text::store_field_metadata().
Reusing it in both send_list_fields() and send_result_set_metadata().
- Adding Protocol_text::store_field_metadata()
- Adding Protocol_text::store_field_metadata_for_list_fields()
Note, this patch also automatically fixed another bug:
MDEV-18685 mysql_list_fields() returns DEFAULT 0 instead of DEFAULT NULL for view columns
The reason for this bug was that Item_ident_for_show::val_xxx() and get_date()
did not check field->is_null() before calling field->val_xxx()/get_date().
Now the default value is correctly sent by Protocol_text::store(Field*).
truncate incorrect values in convert_period_to_month() so that
PERIOD_DIFF never returns a value outside of 2^23 range.
And, for safety, increase buffer sizes for int10_to_str
to be sufficienly big for any int10_to_str result.
Renaming methods:
- Field::make_field(Send_field*) to make_send_field(..)
- Item::make_field(THD *,Send_field *) to make_send_field(..)
- Item::init_make_field(Send_field *, enum_field_type) to init_make_send_field(..)
These names looked similar to other functions that are used
for a very different purpose (creating Field instances):
- Public function "Field * make_field(..)"
- Method "Field *Column_defitinion::make_field(..)"
The rename makes it's easier to search the code using "grep".
Handle string length as size_t, consistently (almost always:))
Change function prototypes to accept size_t, where in the past
ulong or uint were used. change local/member variables to size_t
when appropriate.
This fix excludes rocksdb, spider,spider, sphinx and connect for now.
Item_param::set_value() did not set Item::collation and
Item_param::str_value_ptr.str_charset properly. So both
metadata and data for OUT parameters were sent in a wrong
way to the client.
This patch removes the old implementation of Item_param::set_value()
and rewrites it using Type_handler::Item_param_set_from_value(),
so now setting IN and OUT parameters share the a lot of code.
1. Item_param::set_str() now:
- accepts two additional parameters fromcs, tocs
- sets str_value_ptr, to make sure it's always in sync with str_value,
even without Item_param::convert_str_value()
- does collation.set(tocs, DERIVATION_COERCIBLE),
to make sure that DTCollation is valid even without
Item_param::convert_str_value()
2. Item_param::set_value(), which is used to set OUT parameters,
now reuses Type_handler::Item_param_set_from_value().
3. Cleanup: moving Item_param::str_value_ptr to private,
as it's not needed outside.
4. Cleanup: adding a new virtual method
Settable_routine_parameter::get_item_param()
and using it a few new DBUG_ASSERTs, where
Item_param cannot appear.
After this change:
1. Assigning of IN parameters works as before:
a. Item_param::set_str() is called and sets the value as a binary string
b. The original value is sent to the query used for binary/general logging
c. Item_param::convert_str_value() converts the value from the client
character set to the connection character set
2. Assigning of OUT parameters works in the new way:
a. Item_param::set_str() and sets the value
using the source Item's collation, so both Item::collation
and Item_param::str_value_ptr.str_charset are properly set.
b. Protocol_binary::send_out_parameters() sends the
value to the client correctly:
- Protocol::send_result_set_metadata() uses Item::collation.collation
(which is now properly set), to detect if conversion is needed,
and sends a correct collation ID.
- Protocol::send_result_set_row() calls Type_handler::Item_send_str(),
which uses Item_param::str_value_ptr.str_charset
(which is now properly set) to actually perform the conversion.
If compiling a non DBUG binary with
-DDBUG_ASSERT_AS_PRINTF asserts will be
changed to printf + stack trace (of stack
trace are enabled).
- Changed #ifndef DBUG_OFF to
#ifdef DBUG_ASSERT_EXISTS
for those DBUG_OFF that was just used to enable
assert
- Assert checking that could greatly impact
performance where changed to DBUG_ASSERT_SLOW which
is not affected by DBUG_ASSERT_AS_PRINTF
- Added one extra option to my_print_stacktrace() to
get more silent in case of stack trace printing as
part of assert.
- Added sql/mariadb.h file that should be included first by files in sql
directory, if sql_plugin.h is not used (sql_plugin.h adds SHOW variables
that must be done before my_global.h is included)
- Removed a lot of include my_global.h from include files
- Removed include's of some files that my_global.h automatically includes
- Removed duplicated include's of my_sys.h
- Replaced include my_config.h with my_global.h
Benefits of this patch:
- Removed a lot of calls to strlen(), especially for field_string
- Strings generated by parser are now const strings, less chance of
accidently changing a string
- Removed a lot of calls with LEX_STRING as parameter (changed to pointer)
- More uniform code
- Item::name_length was not kept up to date. Now fixed
- Several bugs found and fixed (Access to null pointers,
access of freed memory, wrong arguments to printf like functions)
- Removed a lot of casts from (const char*) to (char*)
Changes:
- This caused some ABI changes
- lex_string_set now uses LEX_CSTRING
- Some fucntions are now taking const char* instead of char*
- Create_field::change and after changed to LEX_CSTRING
- handler::connect_string, comment and engine_name() changed to LEX_CSTRING
- Checked printf() related calls to find bugs. Found and fixed several
errors in old code.
- A lot of changes from LEX_STRING to LEX_CSTRING, especially related to
parsing and events.
- Some changes from LEX_STRING and LEX_STRING & to LEX_CSTRING*
- Some changes for char* to const char*
- Added printf argument checking for my_snprintf()
- Introduced null_clex_str, star_clex_string, temp_lex_str to simplify
code
- Added item_empty_name and item_used_name to be able to distingush between
items that was given an empty name and items that was not given a name
This is used in sql_yacc.yy to know when to give an item a name.
- select table_name."*' is not anymore same as table_name.*
- removed not used function Item::rename()
- Added comparision of item->name_length before some calls to
my_strcasecmp() to speed up comparison
- Moved Item_sp_variable::make_field() from item.h to item.cc
- Some minimal code changes to avoid copying to const char *
- Fixed wrong error message in wsrep_mysql_parse()
- Fixed wrong code in find_field_in_natural_join() where real_item() was
set when it shouldn't
- ER_ERROR_ON_RENAME was used with extra arguments.
- Removed some (wrong) ER_OUTOFMEMORY, as alloc_root will already
give the error.
TODO:
- Check possible unsafe casts in plugin/auth_examples/qa_auth_interface.c
- Change code to not modify LEX_CSTRING for database name
(as part of lower_case_table_names)
The problem happened because Item_ident_for_show::field_type() always
returned MYSQL_TYPE_DOUBLE and ignored the actual data type of the
referenced Field. As a result, the execution always used
Item_ident_for_show::val_real() to send the default value of the field,
so most default values for non-numeric types were displayed as '0'.
This patch:
1. Cleanup:
a. Removes Send_field::charsetnr, as it's been unused since
introduction of Item::charset_for_protocol() in MySQL-5.5.
b. Adds the "const" qualifier to Field::char_length().
This is needed for (5.a), see below.
2. Introduces a new virtual method Type_handler::charset_for_protocol(),
returning item->collation.collation for string data types, or
&my_charset_bin for non-string data types.
3. Changes Item::charset_for_protocol() from virtual to non-virtual.
It now calls type_handler()->charset_for_protocol().
As a good side effect, duplicate code in Item::charset_for_protocol() and
Item_temporal_hybrid_func::charset_for_protocol() is now gone.
4. Fixes Item_ident_for_show::field_type() to correctly return
its data type according to the data type of the referenced field.
This actually fixes the problem reported in MDEV-11672.
Now the default value is sent using a correct method, e.g.
val_str() for VARCHAR/TEXT, or val_int() for INT/BIGINT.
This required additional changes:
a. in DBUG_ASSERT in Protocol::store(const char *,size_t,CHARSET_INFO),
This method is now used by mysqld_list_fields(), which
(unlike normal SELECT queries) does not set
field_types/field_pos/field_count.
b. Item_ident_for_show::Item_ident_for_show() now set standard attributes
(collation, decimals, max_length, unsigned_flag) according to the
referenced field, to make charset_for_protocol() return the correct
value and to make mysqld_list_fields() correctly send default
values.
5. In order to share the code between Item_field::set_field() and
Item_ident_for_show::Item_ident_for_show():
a. Introduces a new method Type_std_attributes::set(const Field*)
b. To make (a) possible, moves Item::fix_char_length() from Item
to Type_std_attributes, also moves char_to_byte_length_safe()
from item.h to sql_type.h
c. Additionally, moves Item::fix_length_and_charset() and
Item::max_char_length() from Item to Type_std_attributes.
This is not directly needed for the fix and is done just for symmetry
with fix_char_length(), as these three methods are directly related
to each other.
