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MDEV-28835 Assertion `(length % 4) == 0' failed in my_lengthsp_utf32 on INSERT

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Problem:

Item_func_date_format::val_str() and make_date_time() did not take into
account that the format string and the result string
(separately or at the same time) can be of a tricky character set
like UCS2, UTF16, UTF32. As a result, DATE_FORMAT() could generate
an ill-formed result which crashed on DBUG_ASSERTs testing well-formedness
in other parts of the code.

Fix:

1. class String changes
   Removing String::append_with_prefill(). It was not compatible with
   tricky character sets. Also it was inconvenient to use and required
   too much duplicate code on the caller side.
   Adding String::append_zerofill() instead. It's compatible with tricky
   character sets and is easier to use.
   Adding helper methods Static_binary_string::q_append_wc() and
   String::append_wc(), to append a single wide character
   (a Unicode code point in my_wc_t).

2. storage/spider changes
   Removing spider_string::append_with_prefill().
   It used String::append_with_prefix() inside, but it was unused itself.

3. Changing tricky charset incompatible code pieces in make_date_time()
   to compatible replacements:

   - Fixing the loop scanning the format string to iterate in terms
     of Unicode code points (using mb_wc()) rather than in terms
     of "char" items.
   - Using append_wc(my_wc_t) instead of append(char) to append
     a single character to the result string.
   - Using append_zerofill() instead of append_with_prefill() to
     append date/time numeric components to the result string.
This commit is contained in:
Alexander Barkov
2023-07-19 15:10:47 +04:00
parent 3626379d42
commit e2da748c29
9 changed files with 280 additions and 113 deletions
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18
sql/sql_string.cc
View File

@ -649,24 +649,6 @@ bool String::append_parenthesized(long nr, int radix)
}
bool String::append_with_prefill(const char *s,uint32 arg_length,
uint32 full_length, char fill_char)
{
int t_length= arg_length > full_length ? arg_length : full_length;
if (realloc_with_extra_if_needed(str_length + t_length))
return TRUE;
t_length= full_length - arg_length;
if (t_length > 0)
{
bfill(Ptr+str_length, t_length, fill_char);
str_length=str_length + t_length;
}
append(s, arg_length);
return FALSE;
}
int Static_binary_string::strstr(const Static_binary_string &s, uint32 offset)
{
if (s.length()+offset <= str_length)