Commit 61e62116 authored by unknown's avatar unknown
Browse files

A fix (bug #5497: COMPRESS() returns NULL for large strings).

parent 736963b5

mysql-test/r/func_compress.result

+4 −0
Original line number Diff line number Diff line
@@ -68,3 +68,7 @@ Warnings: 
Error	1259	ZLIB: Input data corrupted

Error	1256	Uncompressed data size too large; the maximum size is 1048576 (probably, length of uncompressed data was corrupted)

drop table t1;

set @@max_allowed_packet=1048576*100;

select length(compress(repeat('aaaaaaaaaa', 10000000)));

length(compress(repeat('aaaaaaaaaa', 10000000)))

97214

mysql-test/t/func_compress.test

+7 −0
Original line number Diff line number Diff line
@@ -35,3 +35,10 @@ select length(a) from t1; 
select length(uncompress(a)) from t1;

drop table t1;





#

# Bug #5497: a problem with large strings

#



set @@max_allowed_packet=1048576*100;

select length(compress(repeat('aaaaaaaaaa', 10000000)));

sql/item_strfunc.cc

+9 −3
Original line number Diff line number Diff line
@@ -2723,11 +2723,17 @@ String *Item_func_compress::val_str(String *str) 
   compress(compress(compress(...)))

   I.e. zlib give number 'at least'..

  */

  ulong new_size= (ulong)((res->length()*120)/100)+12;

  ulong new_size= res->length() + res->length() / 5 + 12;



  buffer.realloc((uint32)new_size + 4 + 1);

  Byte *body= ((Byte*)buffer.ptr()) + 4;

  // Will check new_size overflow: new_size <= res->length()

  if (((uint32) new_size <= res->length()) || 

      buffer.realloc((uint32) new_size + 4 + 1))

  {

    null_value= 1;

    return 0;

  }



  Byte *body= ((Byte*)buffer.ptr()) + 4;



  // As far as we have checked res->is_empty() we can use ptr()

  if ((err= compress(body, &new_size,