This did not server any real purpose and also made it too difficult to add
asserts for string memory overrwrites.
Moved all functionallity from Static_binary_string to Binary_string.
Other things:
- Added asserts to q_xxx and qs_xxx functions to check for memory overruns
- Fixed wrong test in String_buffer::set_buffer_if_not_allocated().
The idea is to reuse allocated buffers (to avoid extra allocs), which
the code did not do.
TO_CHAR(expr, fmt)
- expr: required parameter, data/time/timestamp type expression
- fmt: optional parameter, format string, supports
YYYY/YYY/YY/RRRR/RR/MM/MON/MONTH/MI/DD/DY/HH/HH12/HH24/SS and special
characters. The default value is "YYYY-MM-DD HH24:MI:SS"
In Oracle, TO_CHAR() can also be used to convert numbers to strings, but
this is not supported. This will gave an error in this patch.
Other things:
- If format strings is a constant, it's evaluated only once and if there
is any errors in it, they are given at once and the statement will abort.
Original author: woqutech
Lots of optimizations and cleanups done as part of review
- Moved out creating StringBuffers in loops and instead create them
outside and just reset the buffer if it was not allocated (to avoid
a possible malloc/free for every entry)
Other things related to set_buffer_if_not_allocated()
- Changed Valuebuffer to not call set_buffer_if_not_allocated() when
it is created.
- Fixed geometry functions to reset string length before calling
String::reserve(). This is because one should not access length()
of an undefined.
- Added Item_func_conv_charset::save_in_field() as the item is using
str_value to store cached values, which conflicts with
Item::save_str_in_field().
- Changed Item_proc_string to not store the string value in sql_string
as this clashes with Item::save_str_in_field().
- Locally store value of full_name_cstring() in analyse::end_of_records()
as Item::save_str_in_field() may overwrite it.
- Marked some strings as set_thread_specific()
- Added String::free_buffer() to be used internally in String functions
to just free the buffer but not reset other String values.
- Fixed uses_buffer_owned_by() to check for allocated length instead of
strlength, which could be marked MEM_UNDEFINED().
The problem was that when one used String::alloc() to allocate a string,
the String ensures that there is space for an extra NULL byte in the
buffer and if not, reallocates the string. This is a problem with the
String::set_int() that calls alloc(21), which forces extra
malloc/free calls to happen.
- We do not anymore re-allocate String if alloc() is called with the
Allocated_length. This reduces number of malloc() allocations,
especially one big re-allocation in Protocol::send_result_Set_metadata()
for almost every query that produced a result to the connnected client.
- Avoid extra mallocs when using LONGLONG_BUFFER_SIZE
This can now be done as alloc() doesn't increase buffers if new length is
not bigger than old one.
- c_ptr() is redesigned to be safer (but a bit longer) than before.
- Remove wrong usage of c_ptr_quick()
c_ptr_quick() was used in many cases to get the pointer to the used
buffer, even when it didn't need to be \0 terminated. In this case
ptr() is a better substitute.
Another problem with c_ptr_quick() is that it did not guarantee that
the string would be \0 terminated.
- item_val_str(), an API function not used currently by the server,
now always returns a null terminated string (before it didn't always
do that).
- Ensure that all String allocations uses STRING_PSI_MEMORY_KEY. The old
mixed usage of performance keys caused assert's when String buffers
where shrunk.
- Binary_string::shrink() is simplifed
- Fixed bug in String(const char *str, size_t len, CHARSET_INFO *cs) that
used Binary_string((char *) str, len) instead of Binary_string(str,len).
- Changed argument to String() creations and String.set() functions to use
'const char*' instead of 'char*'. This ensures that Alloced_length is
not set, which gives safety against someone trying to change the
original string. This also would allow us to use !Alloced_length in
c_ptr() if needed.
- Changed string_ptr_cmp() to use memcmp() instead of c_ptr() to avoid
a possible malloc during string comparision.
This follows up commit
commit 94a520ddbe and
commit 7c5519c12d.
After these changes, the default test suites on a
cmake -DWITH_UBSAN=ON build no longer fail due to passing
null pointers as parameters that are declared to never be null,
but plenty of other runtime errors remain.
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.
Problem:
The crash happened in FORMAT(double, dec>=31, 'de_DE').
The patch for MDEV-23118 (commit 0041dacc1b)
did not take into account that String::set_real() has a limit of 31
(FLOATING_POINT_DECIMALS) fractional digits. So for the range of 31..38
digits, set_real() switches to use:
- my_fcvt() - decimal point notation, e.g. 1.9999999999
- my_gcvt() - scientific notation, e.g. 1e22
my_gcvt() returned a shorter string than Item_func_format::val_str_ascii()
expected to get after the my_fcvt() call, so it crashed on assert.
Solution:
We cannot extend set_real() to use the my_fcvt() mode for the range of
31..38 fractional digits, because set_real() is used in a lot of places
and such a change will break everything.
Introducing String::set_fcvt() which always prints using my_fcvt()
for the whole range of decimals 0..38, supported by the FORMAT() function.
The code did not take into account that:
- U+005C (backslash) can occupy more than mbminlen characters (e.g. in sjis)
- Some character sets do not have a code for U+005C (e.g. swe7)
Adding a new function my_wc_to_printable into MY_CHARSET_HANDLER to
cover all special cases easier.
Introduced a print_key_value function to makes sure that the trace prints data in readable format
for readable characters and the rest of the characters are printed as hexadecimal.
copy_if_not_alloced() did not handle situations when
"from" is a constant string pointing to a substring of "to",
so this code part freed "to" but then tried to copy its old (already freed)
content to a new buffer:
if (to->realloc(from_length))
return from;
if ((to->str_length=MY_MIN(from->str_length,from_length)))
memcpy(to->Ptr,from->Ptr,to->str_length);
Adding a new code piece that catches such constant substrings
and propery reallocs "to" to preserve its important part referenced
by "from".
Bug was introduced in this commit:
commit: a9ca819897
Call alloc() instead of realloc()
Use alloc() if we don't need original string (avoid copy)
Removed not needed test of str_length in sql_string.cc
copy_if_not_alloced() was forgotten when changing realloc()'s to alloc()'s.
Changing it now.
This warning come from a copy() operation of type:
memcpy(ptr, ptr+A, B), which is safe but produces a warning
when run with valgrind.
To avoid the warning, I added copy_or_move() method which uses
memmove() instead of memcpy().
In 10.3 the change in item_strfunc::Item_func_concat() has to be mirroed
in Item_func_concat_oracle() to avoid future valgrind warnings.
Modern compilers (such as GCC 8) emit warnings that the
'register' keyword is deprecated and not valid C++17.
Let us remove most use of the 'register' keyword.
Code in 'extra/' is not touched.
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.
Main problem was that no log-event print function checked for disk
full error on the IO_CACHE.
All changes in this patch only affects mysqlbinlog, not the server!
- Changed all log-event print functions to return 1 on error
- Fixed memory usage when not using --flashback.
- Added printing of number of rows in row events. Can be disabled with
--print-row-count=0
- Print annotated rows when using mysqlbinlog --short-form
- Fixed that mysqlbinlog --debug works
- Fixed create_drop_binlog.test test failure
- Reorganized fields in PRINT_EVENT_INFO to be according to size to
optimize storage
- Don't change print_row_event_position or print_row_counts if set by user
- Remove some testing of argument to my_free is 0
- base64-output=never is now supported and works in all context
- Updated help information for --base64-output and --short-form
- print_row_count is now on by default. Reset automatically if --short-form
is used
- Removed obsolote warning for mysql 5.6.0
- More DBUG_PRINT for mysqltest.cc
- my_b_write_byte() now checks for flush failures. This fixed a memory
overrun on disk full
- my_b_printf() now returns 1 on failure, 0 on ok. This simplifies code
and no old code was using the old return value of my_b_printf().
- my_b_Write_backtick_quote() now returns 1 on failure and 0 on ok
- Fixed some error conditions in log printing that was not previously
handled.
- Slave_rows_error_report() can now handle longlong positions
- Write_on_release_cache() rewritten so that we can detect errors
on flush. Not depending on automatic release anymore.
- Changed types for Pos and End_log_pos to 64 bit in SHOW BINLOG EVENTS
- Fixed that copy_event_cache_to_string_and_reinit() works with strings
longer than 4G (Changed to use LEX_STRING instead of String)
- Restricted binlog_rows_event_max_size to UINT32_MAX-1 as String's are
anyway restricted to UINT32_MAX
- Fixed bug in rpl_binlog_state::write_to_iocache() which hide write
failures (duplicate variable name)
- Fixed bug in String::append if original string was not allocated
- Stop mysqlbinlog output at once if there is an error.
- Before printing error message, flush result file. This ensures that
the error message is printed last. (Easier to find)
