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Fix code in make_sortkey() that only worked by chance

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(assert added by MySQL verified that strnxfrm can only *increase*
the string length if from == to, and the latter is a random
decision made by individual items and String::realloc).

Fix it by avoiding the memcpy in the first place.
This commit is contained in:
Sergei Golubchik 2014-02-26 16:15:52 +01:00
parent dd13db6f4a
commit 9e135ce19f
1 changed files with 5 additions and 12 deletions
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17
sql/filesort.cc
View file

@ -903,8 +903,8 @@ static void make_sortkey(register SORTPARAM *param,
if (maybe_null)
*to++=1;
/* All item->str() to use some extra byte for end null.. */
String tmp((char*) to,sort_field->length+4,cs);
char *tmp_buffer= param->tmp_buffer ? param->tmp_buffer : (char*)to;
String tmp(tmp_buffer, param->sort_length, cs);
String *res= item->str_result(&tmp);
if (!res)
{
@ -929,17 +929,9 @@ static void make_sortkey(register SORTPARAM *param,
length= res->length();
if (sort_field->need_strxnfrm)
{
char *from=(char*) res->ptr();
uint tmp_length __attribute__((unused));
if ((uchar*) from == to)
{
DBUG_ASSERT(sort_field->length >= length);
set_if_smaller(length,sort_field->length);
memcpy(param->tmp_buffer,from,length);
from=param->tmp_buffer;
}
tmp_length= my_strnxfrm(cs,to,sort_field->length,
(uchar*) from, length);
tmp_length= my_strnxfrm(cs, to ,sort_field->length,
(uchar*) res->ptr(), length);
DBUG_ASSERT(tmp_length == sort_field->length);
}
else
@ -960,6 +952,7 @@ static void make_sortkey(register SORTPARAM *param,
store_length(to + sort_field_length, length,
sort_field->suffix_length);
}
/* apply cs->sort_order for case-insensitive comparison if needed */
my_strnxfrm(cs,(uchar*)to,length,(const uchar*)res->ptr(),length);
cs->cset->fill(cs, (char *)to+length,diff,fill_char);
}