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Bug#11753363 (bug#44793) CHARACTER SETS: CASE CLAUSE, UCS2 OR UTF32, FAILURE

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Problem: in case of string CASE/WHEN arguments with different
character sets, Item_func_case::find_item() called comparator
cmp_items[x] on mixed character set Items, so a 8-bit value could
be errouneously referenced to as being utf16/utf32 value,
which led to crash on DBUG_ASSERT() because of wrong value length.
This was wrong, as string comparator expects arguments in the same
character set.

Fix: modify Item_func_case's argument list after calling
agg_arg_charsets_for_comparison() - put the Items in "agg" array
back to "args", because some of the Items in the "agg" array might
have been changed to character set converters:
- to Item_func_conv_charset for non-constant items
- to Item_string for constant items

In other words, perform the same substitution which is done in
all other operations string comparison or string result operations:

Replace
  CASE         latin1_item              WHEN utf16_item THEN ... END
to
  CASE CONVERT(latin1_item USING utf16) WHEN utf16_item THEN ... END

Replace
  CASE utf16_item WHEN         latin1_item              THEN ... END
to
  CASE utf16_item WHEN CONVERT(latin1_item USING utf16) THEN ... END


  @ mysql-test/r/ctype_utf16.result
  @ mysql-test/r/ctype_utf32.result
  @ mysql-test/t/ctype_utf16.test
  @ mysql-test/t/ctype_utf32.test
  Adding tests

  @ sql/item_cmpfunc.cc
  Put "agg" back to "args".

  @ sql/sql_string.cc
  Backporting a fix for String::set_or_copy_aligned() from 5.6,
  for better test coverage:
  "SELECT _utf16 0x61" should expand the string to 0x0061 rather
  than to 0x000061.
  This fix was made in 5.6 under terms of "WL#4616 Implement UTF16-LE".
This commit is contained in:
Alexander Barkov
2011-03-01 15:09:37 +03:00
parent 48126a574c
commit 8a83d30436
6 changed files with 97 additions and 9 deletions
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4
sql/sql_string.cc
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@ -252,8 +252,8 @@ bool String::copy_aligned(const char *str,uint32 arg_length, uint32 offset,
CHARSET_INFO *cs)
{
/* How many bytes are in incomplete character */
offset= cs->mbmaxlen - offset; /* How many zeros we should prepend */
DBUG_ASSERT(offset && offset != cs->mbmaxlen);
offset= cs->mbminlen - offset; /* How many zeros we should prepend */
DBUG_ASSERT(offset && offset != cs->mbminlen);
uint32 aligned_length= arg_length + offset;
if (alloc(aligned_length))