strict aliasing violations.
Essentially, the problem is that large parts of the server were
developed in simpler times (last decades, pre C99 standard) when
strict aliasing and compilers supporting such optimizations were
rare to non-existent. Thus, when compiling the server with a modern
compiler that uses strict aliasing rules to perform optimizations,
there are several places in the code that might trigger undefined
behavior.
As evinced by some recent bugs, GCC does a somewhat good of job
misoptimizing such code, but on the other hand also gives warnings
about suspicious code. One problem is that the warnings aren't
always accurate, yet we can't afford to just shut them off as we
might miss real cases. False-positive cases are aggravated mostly
by casts that are likely to trigger undefined behavior.
The solution is to start a cleanup process focused on fixing and
reducing the amount of strict-aliasing related warnings produced
by GCC and others compilers. A good deal of noise reduction can
be achieved by just removing useless casts that are product of
historical cruft and are likely to trigger undefined behavior if
dereferenced.
BUILD/*: Add valgrind_configs=--with-valgrind.
BUILD/*: Remove -USAFEMALLOC from valgrind_flags.
configure.in: Add AC_ARG_WITH(valgrind) and HAVE_VALGRIND.
include/my_sys.h: Define a number of MEM_ wrappers for VALGRIND_ functions.
include/my_sys.h: Make TRASH do MEM_UNDEFINED().
include/m_string.h: Remove unused macro bzero_if_purify(A,B).
_mymalloc(): Declare MEM_UNDEFINED() on the allocated memory.
_myfree(): Declare MEM_NOACCESS() on the freed memory.
storage/innobase/include/univ.i: Enable UNIV_DEBUG_VALGRIND based on
HAVE_VALGRIND rather than HAVE_purify.
Possible things to do:
* In my_global.h, remove the defined(HAVE_purify) condition
from the _WIN32 uint3korr().
* In my_global.h *int*korr(), use | instead of +
in order to keep the Valgrind V bits accurate
* Consider replacing HAVE_purify with HAVE_VALGRIND
* Use VALGRIND_CREATE_BLOCK, VALGRIND_DISCARD in mem_root and similar places
The server could be tricked to read packets indefinitely if it
received a packet larger than the maximum size of one packet.
This problem is aggravated by the fact that it can be triggered
before authentication.
The solution is to no skip big packets for non-authenticated
sessions. If a big packet is sent before a session is authen-
ticated, a error is returned and the connection is closed.
to cleanup open connections
It was possible to UNINSTALL storage engine plugin when binding
between THD object and storage engine is still active (e.g. in
the middle of transaction).
To avoid unclean deactivation (uninstall) of storage engine plugin
in the middle of transaction, additional storage engine plugin
lock is acquired by thd_set_ha_data().
If ha_data is not null and storage engine plugin was not locked
by thd_set_ha_data() in this connection before, storage engine
plugin gets locked.
If ha_data is null and storage engine plugin was locked by
thd_set_ha_data() in this connection before, storage engine
plugin lock gets released.
If handlerton::close_connection() didn't reset ha_data, server does
it immediately after calling handlerton::close_connection().
Note that this is just a framework fix, storage engines must switch
to thd_set_ha_data() from thd_ha_data() if they want to see fit.
Several problems addressed:
1. The maximum value for --open_files_limit on non-windows boxes
is now raised to UINT_MAX (the maximum possible without significant
changes in the code). The maximum value on windows is kept to be
2048 due to a known limitation (bug 24509).
2. mysqld_safe now supports --open_files_limit=xx in addition to
--open-files-limit=xx
3. mysqld_safe always passes through --open[_-]files[_-]limit
to the underlying mysqld. It used to pass it through only if it
the user running the script has access to the root directory or
there was an --user argument specified.
4. Fixed a prototype in my_file.c to match its counterpart in
the other #ifdef branch.
A client doing multiple mysql_library_init() and
mysql_library_end() calls over the lifetime of the process may
experience lost character set data, potentially even a
SIGSEGV.
This patch reinstates the reloading of character set data when
a mysql_library_init() is done after a mysql_library_end().
When compressed myisam files are opened, they are always memory mapped
sometimes causing memory swapping problems.
When we mmap the myisam compressed tables of size greater than the memory
available, the kswapd0 process utilization is very high consuming 30-40% of
the cpu. This happens only with linux kernels older than 2.6.9
With newer linux kernels, we don't have this problem of high cpu consumption
and this option may not be required.
The option 'myisam_mmap_size' is added to limit the amount of memory used for
memory mapping of myisam files. This option is not dynamic.
The default value on 32 bit system is 4294967295 bytes and on 64 bit system it
is 18446744073709547520 bytes.
Note: Testcase only tests the option variable. The actual bug has be to
tested manually.
strmov() is not guaranteed to work correctly on overlapping
source and destination buffers. On some OSes it may work,
but Fedora 12 has a stpcpy() that's not working correctly
on overlapping buffers.
Fixed to use the overlap-safe version of strmov instead.
Re-vitalized the overlap-safe version of strmov.
As documented in the bug report, the double checked locking
pattern has inherent issues, and cannot guarantee correct
initialization.
This patch replaces the logic in init_available_charsets()
with the use of pthread_once(3). A wrapper function,
my_pthread_once(), is introduced and is used in lieu of direct
calls to init_available_charsets(). Related defines
MY_PTHREAD_ONCE_* are also introduced.
For the Windows platform, the implementation in lp:sysbench is
ported. For single-thread use, a simple define calls the
function and sets the pthread_once control variable.
Charset initialization is modified to use my_pthread_once().
Bug#31621: Windows server hanging during shutdown using named pipes
and idle connection
Problem: when idle pipe connection is forcefully closed with KILL
statement or when the server goes down, thread that is closing connection
would hang infinitely in CloseHandle(). The reason for the hang is that
named pipe operations are performed synchronously. In this mode all IOs
on pipe are serialized, that is CloseHandle() will not abort ReadFile()
in another thread, but wait for ReadFile() to complete.
The fix implements asynchrnous mode for named pipes, where operation of file
are not synchronized. Read/Write operation would fire an async IO and wait for
either IO completion or timeout.
Note, that with this patch timeouts are properly handled for named pipes.
Post-review: Win32 timeout code has been fixed for named pipes and shared
memory. We do not store pointer to NET in vio structure, only the read and
write timeouts.
BUG#47073 - valgrind errs, corruption,failed repair of partition,
low myisam_sort_buffer_size
Fixed race conditions discovered with the provided test case and
stabilized test case.
Backport from 6.0 to 5.1.
Only those sync points are included, which are used in debug_sync.test.
The Debug Sync Facility allows to place synchronization points
in the code:
open_tables(...)
DEBUG_SYNC(thd, "after_open_tables");
lock_tables(...)
When activated, a sync point can
- Send a signal and/or
- Wait for a signal
Nomenclature:
- signal: A value of a global variable that persists
until overwritten by a new signal. The global
variable can also be seen as a "signal post"
or "flag mast". Then the signal is what is
attached to the "signal post" or "flag mast".
- send a signal: Assign the value (the signal) to the global
variable ("set a flag") and broadcast a
global condition to wake those waiting for
a signal.
- wait for a signal: Loop over waiting for the global condition until
the global value matches the wait-for signal.
Please find more information in the top comment in debug_sync.cc
or in the worklog entry.
Restore a stub of the removed mysql_odbc_escape_string function
to fix a ABI breakage. The function was intended to be private
and used only by Connector/ODBC, but, unfortunately, it was exported
as part of the ABI. Nonetheless, only a stub is restored as the
original function is inherently broken and shouldn't be used.
This restoration only applies to MySQL 5.0. This will be addressed
differently in later versions -- reworked library versioning.
can crash under load
Backport from 5.1.
Does also include key cache fixes from:
Bug 44068 (RESTORE can disable the MyISAM Key Cache)
Bug 40944 (Backup: crash after myisampack)
CREATE TABLE...LIKE...
The mysql server option 'sync_frm' is ignored when table is created with
syntax CREATE TABLE .. LIKE..
Fixed by adding the MY_SYNC flag and calling my_sync() from my_copy() when
the flag is set.
In mysql_create_table(), when the 'sync_frm' is set, MY_SYNC flag is passed
to my_copy().
Note: TestCase is not attached and can be tested manually using debugger.
with gcc 4.3.2
This patch fixes a number of GCC warnings about variables used
before initialized. A new macro UNINIT_VAR() is introduced for
use in the variable declaration, and LINT_INIT() usage will be
gradually deprecated. (A workaround is used for g++, pending a
patch for a g++ bug.)
GCC warnings for unused results (attribute warn_unused_result)
for a number of system calls (present at least in later
Ubuntus, where the usual void cast trick doesn't work) are
also fixed.
- Define and pass compile time path variables as pre-processor definitions to
mimic the makefile build.
- Set new CMake version and policy requirements explicitly.
- Changed DATADIR to MYSQL_DATADIR to avoid conflicting definition in
Platform SDK header ObjIdl.h which also defines DATADIR.
not logged
Errors encountered during initialization of the SSL subsystem
are printed to stderr, rather than to the error log.
This patch adds a parameter to several SSL init functions to
report the error (if any) out to the caller. The function
init_ssl() in mysqld.cc is moved after the initialization of
the log subsystem, so that any error messages can be logged to
the error log. Printing of messages to stderr has been
retained to get diagnostic output in a client context.
it returns misleading 'table is full'
Innodb returns a misleading error message "table is full"
when the number of active concurrent transactions is greater
than 1024.
Fixed by adding errorcode "ER_TOO_MANY_CONCURRENT_TRXS" to the
error codes. Innodb should return HA_TOO_MANY_CONCURRENT_TRXS
to mysql which is then mapped to ER_TOO_MANY_CONCURRENT_TRXS
Note: testcase is not written as this was reproducible only by
changing innodb code.
A REPLACE in the MERGE engine is actually a REPLACE
into one (FIRST or LAST) of the underlying MyISAM
tables. So in effect the server works on the meta
data of the MERGE table, while the real insert happens
in the MyISAM table.
The MERGE table has no index, while MyISAM has a
unique index. When a REPLACE into a MERGE table (
and the REPLACE conflicts with a duplicate in a
child table) is done, we try to access the duplicate
key information for the MERGE table. This information
actually does not exist, hence this results in a crash.
The problem can be resolved by modifying the MERGE
engine to provide us the duplicate key information
directly, instead of just returning the MyISAM index
number as the error key. Then the SQL layer (or "the
server") does not try to access the key_info of the
MERGE table, which does not exist.
The current patch modifies the MERGE engine to provide
the position for a record where a unique key violation
occurs.
