Bug#18282 "INFORMATION_SCHEMA.TABLES provides inconsistent info about invalid views"
This bug caused crashes or resulted in wrong data being returned
when one tried to obtain information from I_S tables about views
using stored functions.
It was caused by the fact that we were using LEX representing
statement which were doing select from I_S tables as active LEX
when contents of I_S table were built. So state of this LEX both
affected and was affected by open_tables() calls which happened
during this process. This resulted in wrong behavior and in
violations of some of invariants which caused crashes.
This fix tries to solve this problem by properly saving/resetting
and restoring part of LEX which affects and is affected by the
process of opening tables and views in get_all_tables() routine.
To simplify things we separated this part of LEX in a new class
and made LEX its descendant.
The IN() function uses agg_cmp_type() to aggregate all types of its arguments
to find out some common type for comparisons. In this particular case the
char() and the int was aggregated to double because char() can contain values
like '1.5'. But all strings which do not start from a digit are converted to
0. thus 'a' and 'z' become equal.
This behaviour is reasonable when all function arguments are constants. But
when there is a field or an expression this can lead to false comparisons. In
this case it makes more sense to coerce constants to the type of the field
argument.
The agg_cmp_type() function now aggregates types of constant and non-constant
items separately. If some non-constant items will be found then their
aggregated type will be returned. Thus after the aggregation constants will be
coerced to the aggregated type.
The order of acquiring LOCK_mysql_create_db
and wait_if_global_read_lock() was wrong. It could happen
that a thread held LOCK_mysql_create_db while waiting for
the global read lock to be released. The thread with the
global read lock could try to administrate a database too.
It would first try to lock LOCK_mysql_create_db and hang...
The check if the current thread has the global read lock
is done in wait_if_global_read_lock(), which could not be
reached because of the hang in LOCK_mysql_create_db.
Now I exchanged the order of acquiring LOCK_mysql_create_db
and wait_if_global_read_lock(). This makes
wait_if_global_read_lock() fail with an error message for
the thread with the global read lock. No deadlock happens.
In multi-table delete a table for delete can't be used for selecting in
subselects. Appropriate error was raised but wasn't checked which leads to a
crash at the execution phase.
The mysql_execute_command() now checks for errors before executing select
for multi-delete.
argument can lead to a wrong result.
md5() and sha() functions treat their arguments as case sensitive strings.
But when they are compared their arguments were compared as a case
insensitive strings which leads to two functions with different arguments
and thus different results to being identical. This can lead to a wrong
decision made in the range optimizer and thus lead to a wrong result set.
Item_func_md5::fix_length_and_dec() and Item_func_sha::fix_length_and_dec()
functions now set binary collation on their arguments.
duplicate fields removed, st_mysql_storage_engine added to support
run-time handlerton initialization (no compiler warnings), handler API
is now tied to MySQL version, handlerton->plugin mapping added
(slot-based), dummy default_hton removed, plugin-type-specific
initialization generalized, built-in plugins are now initialized too,
--default-storage-engine no longer needs a list of storage engines
in handle_options().
mysql-test-run.pl bugfixes
When reading a view definition from a .frm file it was
throwing a SQL error if the DEFINER user is not defined.
Changed it to a warning to match the (documented) case
when a view with undefined DEFINER user is created.
The check for view security was lacking several points :
1. Check with the right set of permissions : for each table ref that
participates in a view there were the right credentials to use in it's
security_ctx member, but these weren't used for checking the credentials.
This makes hard enforcing the SQL SECURITY DEFINER|INVOKER property
consistently.
2. Because of the above the security checking for views was just ruled out
in explicit ways in several places.
3. The security was checked only for the columns of the tables that are
brought into the query from a view. So if there is no column reference
outside of the view definition it was not detecting the lack of access to
the tables in the view in SQL SECURITY INVOKER mode.
The fix below tries to fix the above 3 points.
The Item_func_concat::val_str() function tries to make as less re-allocations
as possible. This results in appending strings returned by 2nd and next
arguments to the string returned by 1st argument if the buffer for the first
argument has enough free space. A constant subselect is evaluated only once
and its result is stored in an Item_cache_str. In the case when the first
argument of the concat() function is such a subselect Item_cache_str returns
the stored value and Item_func_concat::val_str() append values of other
arguments to it. But for the next row the value in the Item_cache_str isn't
restored because the subselect is a constant one and it isn't evaluated second
time. This results in appending string values of 2nd and next arguments to the
result of the previous Item_func_concat::val_str() call.
The Item_func_concat::val_str() function now checks whether the first argument
is a constant one and if so it doesn't append values of 2nd and next arguments
to the string value returned by it.
