If a stored function that contains a drop temporary table statement
is invoked by a create temporary table of the same name may cause
a server crash. The problem is that when dropping a table no check
is done to ensure that table is not being used by some outer query
(or outer statement), potentially leaving the outer query with a
reference to a stale (freed) table.
The solution is when dropping a temporary table, always check if
the table is being used by some outer statement as a temporary
table can be dropped inside stored procedures.
The check is performed by looking at the TABLE::query_id value for
temporary tables. To simplify this check and to solve a bug related
to handling of temporary tables in prelocked mode, this patch changes
the way in which this member is used to track the fact that table is
used/unused. Now we ensure that TABLE::query_id is zero for unused
temporary tables (which means that all temporary tables which were
used by a statement should be marked as free for reuse after it's
execution has been completed).
The general log write function (general_log_print) uses printf style
arguments which need to be pre-processed, meaning that the all arguments
are copied to a single buffer and the problem is that the buffer size is
constant (1022 characters) but queries can be much larger then this.
The solution is to introduce a new log write function that accepts a
buffer and it's length as arguments. The function is to be used when
a formatted output is not required, which is the case for almost all
query write-to-log calls.
This is a incompatible change with respect to the log format of prepared
statements.
of statement breaks binlog.
There were two problems discovered by this bug:
1. Default (current) database is not fixed at the creation time.
That leads to wrong output of DATABASE() function.
2. Database attributes (@@collation_database) are not fixed at
the creation time. That leads to wrong resultset.
Binlog breakage and Query Cache wrong output happened because of
the first problem.
The fix is to remember the current database at the PREPARE-time and
set it each time at EXECUTE.
Bug#21422 GRANT/REVOKE possible inside stored function, probably in a trigger
Bug#17244 GRANT gives strange error message when used in a stored function
GRANT/REVOKE statements are non-transactional (no explicit transaction
boundaries) in nature and hence are forbidden inside stored functions and
triggers, but they weren't being effectively forbidden. Furthermore, the
absence of implict commits makes changes made by GRANT/REVOKE statements to
not be rolled back.
The implemented fix is to issue a implicit commit with every GRANT/REVOKE
statement, effectively prohibiting these statements in stored functions
and triggers. The implicit commit also fixes the replication bug, and looks
like being in concert with the behavior of DDL and administrative statements.
Since this is a incompatible change, the following sentence should be
added to the Manual in the very end of the 3rd paragraph, subclause
13.4.3 "Statements That Cause an Implicit Commit": "Beginning with
MySQL 5.0.??, the GRANT and REVOKE statements cause an implicit commit."
Patch contributed by Vladimir Shebordaev
Faster thr_alarm()
Added 'Opened_files' status variable to track calls to my_open()
Don't give warnings when running mysql_install_db
Added option --source-install to mysql_install_db
I had to do the following renames() as used polymorphism didn't work with Forte compiler on 64 bit systems
index_read() -> index_read_map()
index_read_idx() -> index_read_idx_map()
index_read_last() -> index_read_last_map()
Bug #27417 thd->no_trans_update.stmt lost value inside of SF-exec-stack
Once had been set the flag might later got reset inside of a stored routine
execution stack.
The reason was in that there was no check if a new statement started at time
of resetting.
The artifact affects most of binlogable DML queries. Notice, that multi-update
is wrapped up within
bug@27716 fix, multi-delete bug@29136.
Fixed with saving parent's statement flag of whether the statement modified
non-transactional table, and unioning (merging) the value with that was gained
in mysql_execute_command.
Resettling thd->no_trans_update members into thd->transaction.`member`;
Asserting code;
Effectively the following properties are held.
1. At the end of a substatement thd->transaction.stmt.modified_non_trans_table
reflects the fact if such a table got modified by the substatement.
That also respects THD::really_abort_on_warnin() requirements.
2. Eventually thd->transaction.stmt.modified_non_trans_table will be computed as
the union of the values of all invoked sub-statements.
That fixes this bug#27417;
Computing of thd->transaction.all.modified_non_trans_table is refined to base to
the stmt's value for all the case including insert .. select statement which
before the patch had an extra issue bug@28960.
Minor issues are covered with mysql_load, mysql_delete, and binloggin of insert in
to temp_table select.
The supplied test verifies limitely, mostly asserts. The ultimate testing is defered
for bug@13270, bug@23333.
SP with local variables with non-ASCII names crashed the server.
The server replaces SP local variable names with NAME_CONST calls
when putting statements into the binary log. It used UTF8-encoded
item names as variable names for the replacement inside NAME_CONST
calls. However, statement string may be encoded by any
known character set by the SET NAMES statement.
The server used byte length of UTF8-encoded names to increment
the position in the query string that led to array index overrun.
The subst_spvars function is used to create query string with SP variables
substituted with their values. This string is used later for the binary log
and for the query cache. The problem is that the
query_cache_send_result_to_client function requires some additional space
after the query to store database name and query cache flags. This
space wasn't reserved by the subst_spvars function which led to a memory
corruption and crash.
Now the subst_spvars function reserves additional space for the query cache.
causes full table lock on innodb table.
Also fixes Bug#28502 Triggers that update another innodb table
will block on X lock unnecessarily (duplciate).
Code review fixes.
Both bugs' synopses are misleading: InnoDB table is
not X locked. The statements, however, cannot proceed concurrently,
but this happens due to lock conflicts for tables used in triggers,
not for the InnoDB table.
If a user had an InnoDB table, and two triggers, AFTER UPDATE and
AFTER INSERT, competing for different resources (e.g. two distinct
MyISAM tables), then these two triggers would not be able to execute
concurrently. Moreover, INSERTS/UPDATES of the InnoDB table would
not be able to run concurrently.
The problem had other side-effects (see respective bug reports).
This behavior was a consequence of a shortcoming of the pre-locking
algorithm, which would not distinguish between different DML operations
(e.g. INSERT and DELETE) and pre-lock all the tables
that are used by any trigger defined on the subject table.
The idea of the fix is to extend the pre-locking algorithm to keep track,
for each table, what DML operation it is used for and not
load triggers that are known to never be fired.
SHOW CREATE TABLE or SELECT FROM I_S.
This is the last patch for this bug, which depends on the big
CS patch and was pending.
The problem was that SHOW CREATE statements returned original
queries in the binary character set. That could cause the query
to be unreadable.
The fix is to use original character_set_client when sending
the original query to the client. In order to preserve the query
in mysqldump, 'binary' character set results should be set when
issuing SHOW CREATE statement. If either source or destination
character set is 'binary' , no conversion is performed.
The idea is that since the source character set is no longer
'binary', we fix the destination character set to still produce
valid dumps.
- BUG#11986: Stored routines and triggers can fail if the code
has a non-ascii symbol
- BUG#16291: mysqldump corrupts string-constants with non-ascii-chars
- BUG#19443: INFORMATION_SCHEMA does not support charsets properly
- BUG#21249: Character set of SP-var can be ignored
- BUG#25212: Character set of string constant is ignored (stored routines)
- BUG#25221: Character set of string constant is ignored (triggers)
There were a few general problems that caused these bugs:
1. Character set information of the original (definition) query for views,
triggers, stored routines and events was lost.
2. mysqldump output query in client character set, which can be
inappropriate to encode definition-query.
3. INFORMATION_SCHEMA used strings with mixed encodings to display object
definition;
1. No query-definition-character set.
In order to compile query into execution code, some extra data (such as
environment variables or the database character set) is used. The problem
here was that this context was not preserved. So, on the next load it can
differ from the original one, thus the result will be different.
The context contains the following data:
- client character set;
- connection collation (character set and collation);
- collation of the owner database;
The fix is to store this context and use it each time we parse (compile)
and execute the object (stored routine, trigger, ...).
2. Wrong mysqldump-output.
The original query can contain several encodings (by means of character set
introducers). The problem here was that we tried to convert original query
to the mysqldump-client character set.
Moreover, we stored queries in different character sets for different
objects (views, for one, used UTF8, triggers used original character set).
The solution is
- to store definition queries in the original character set;
- to change SHOW CREATE statement to output definition query in the
binary character set (i.e. without any conversion);
- introduce SHOW CREATE TRIGGER statement;
- to dump special statements to switch the context to the original one
before dumping and restore it afterwards.
Note, in order to preserve the database collation at the creation time,
additional ALTER DATABASE might be used (to temporary switch the database
collation back to the original value). In this case, ALTER DATABASE
privilege will be required. This is a backward-incompatible change.
3. INFORMATION_SCHEMA showed non-UTF8 strings
The fix is to generate UTF8-query during the parsing, store it in the object
and show it in the INFORMATION_SCHEMA.
Basically, the idea is to create a copy of the original query convert it to
UTF8. Character set introducers are removed and all text literals are
converted to UTF8.
This UTF8 query is intended to provide user-readable output. It must not be
used to recreate the object. Specialized SHOW CREATE statements should be
used for this.
The reason for this limitation is the following: the original query can
contain symbols from several character sets (by means of character set
introducers).
Example:
- original query:
CREATE VIEW v1 AS SELECT _cp1251 'Hello' AS c1;
- UTF8 query (for INFORMATION_SCHEMA):
CREATE VIEW v1 AS SELECT 'Hello' AS c1;
The patch contains the following changes:
- Introduce auxilary functions to convenient work with character sets:
- resolve_charset();
- resolve_collation();
- get_default_db_collation();
- Introduce lex_string_set();
- Refactor Table_trigger_list::process_triggers() &
sp_head::execute_trigger() to be consistent with other code;
- Move reusable code from add_table_for_trigger() into
build_trn_path(), check_trn_exists() and load_table_name_for_trigger()
to be used in the following patch.
- Rename triggers_file_ext and trigname_file_ext into TRN_EXT and
TRG_EXT respectively.
Bug 28127 (Some valid identifiers names are not parsed correctly)
Bug 26302 (MySQL server cuts off trailing "*/" from comments in SP/func)
This patch is the second part of a major cleanup, required to fix
Bug 25411 (trigger code truncated).
The root cause of the issue stems from the function skip_rear_comments,
which was a work around to remove "extra" "*/" characters from the query
text, when parsing a query and reusing the text fragments to represent a
view, trigger, function or stored procedure.
The reason for this work around is that "special comments",
like /*!50002 XXX */, were not parsed properly, so that a query like:
AAA /*!50002 BBB */ CCC
would be seen by the parser as "AAA BBB */ CCC" when the current version
is greater or equal to 5.0.2
The root cause of this stems from how special comments are parsed.
Special comments are really out-of-bound text that appear inside a query,
that affects how the parser behave.
In nature, /*!50002 XXX */ in MySQL is similar to the C concept
of preprocessing :
#if VERSION >= 50002
XXX
#endif
Depending on the current VERSION of the server, either the special comment
should be expanded or it should be ignored, but in all cases the "text" of
the query should be re-written to strip the "/*!50002" and "*/" markers,
which does not belong to the SQL language itself.
Prior to this fix, these markers would leak into :
- the storage format for VIEW,
- the storage format for FUNCTION,
- the storage format for FUNCTION parameters, in mysql.proc (param_list),
- the storage format for PROCEDURE,
- the storage format for PROCEDURE parameters, in mysql.proc (param_list),
- the storage format for TRIGGER,
- the binary log used for replication.
In all cases, not only this cause format corruption, but also provide a vector
for dormant security issues, by allowing to tunnel code that will be activated
after an upgrade.
The proper solution is to deal with special comments strictly during parsing,
when accepting a query from the outside world.
Once a query is parsed and an object is created with a persistant
representation, this object should not arbitrarily mutate after an upgrade.
In short, special comments are a useful but limited feature for MYSQLdump,
when used at an *interface* level to facilitate import/export,
but bloating the server *internal* storage format is *not* the proper way
to deal with configuration management of the user logic.
With this fix:
- the Lex_input_stream class now acts as a comment pre-processor,
and either expands or ignore special comments on the fly.
- MYSQLlex and sql_yacc.yy have been cleaned up to strictly use the
public interface of Lex_input_stream. In particular, how the input stream
accepts or rejects a character is private to Lex_input_stream, and the
internal buffer pointers of that class are strictly private, and should not
be tempered with during parsing.
This caused many changes mostly in sql_lex.cc.
During the code cleanup in case MY_LEX_NUMBER_IDENT,
Bug 28127 (Some valid identifiers names are not parsed correctly)
was found and fixed.
By parsing special comments properly, and removing the function
'skip_rear_comments' [sic],
Bug 26302 (MySQL server cuts off trailing "*/" from comments in SP/func)
has been fixed as well.
Coding style: classes start with a capital letter.
Rename some classes related to parsing:
create_field -> Create_field
foreign_key -> Foreign_key
key_part_spec -> Key_part_spec
The root cause of this bug is related to the function skip_rear_comments,
in sql_lex.cc
Recent code changes in skip_rear_comments changed the prototype from
"const uchar*" to "const char*", which had an unforseen impact on this test:
(endp[-1] < ' ')
With unsigned characters, this code filters bytes of value [0x00 - 0x20]
With *signed* characters, this also filters bytes of value [0x80 - 0xFF].
This caused the regression reported, considering cyrillic characters in the
parameter name to be whitespace, and truncated.
Note that the regression is present both in 5.0 and 5.1.
With this fix:
- [0x80 - 0xFF] bytes are no longer considered whitespace.
This alone fixes the regression.
In addition, filtering [0x00 - 0x20] was found bogus and abusive,
so that the code now filters uses my_isspace when looking for whitespace.
Note that this fix is only addressing the regression affecting UTF-8
in general, but does not address a more fundamental problem with
skip_rear_comments: parsing a string *backwards*, starting at end[-1],
is not safe with multi-bytes characters, so that end[-1] can confuse the
last byte of a multi-byte characters with a characters to filter out.
The only known impact of this remaining issue affects objects that have to
meet all the conditions below:
- the object is a FUNCTION / PROCEDURE / TRIGGER / EVENT / VIEW
- the body consist of only *1* instruction, and does *not* contain a
BEGIN-END block
- the instruction ends, lexically, with <ident> <whitespace>* ';'?
For example, "select <ident>;" or "return <ident>;"
- The last character of <ident> is a multi-byte character
- the last byte of this character is ';' '*', '/' or whitespace
In this case, the body of the object will be truncated after parsing,
and stored in an invalid format.
This last issue has not been fixed in this patch, since the real fix
will be implemented by Bug 25411 (trigger code truncated), which is caused
by the very same code.
The real problem is that the function skip_rear_comments is only a
work-around, and should be removed entirely: see the proposed patch for
bug 25411 for details.
If a stored function or a trigger was killed it had aborted but no error
was thrown. This allows the caller statement to continue without a notice.
This may lead to a wrong data being inserted/updated to/deleted as in such
cases the correct result of a stored function isn't guaranteed. In the case
of triggers it allows the caller statement to ignore kill signal and to
waste time because of re-evaluation of triggers that always will fail
because thd->killed flag is still on.
Now the Item_func_sp::execute() and the sp_head::execute_trigger() functions
check whether a function or a trigger were killed during execution and
throws an appropriate error if so.
Now the fill_record() function stops filling record if an error was reported
through thd->net.report_error.
