[Fwd: BUG - different writing and reading of Long value]

Hello developers,

there was some different bug. I found that variables ch1,ch2 ...ch4 may be
Long value. There was problem because sometime ch4<<4 has negative
result. So correct code is:

      case T_LONG | 0x80: {

              //added by kozusznikj

               long ch1, ch2, ch3, ch4;

               long v_low,v_high;

              Â

               ch1 = inputStream.read();

               ch2 = inputStream.read();

               ch3 = inputStream.read();

               ch4 = inputStream.read();

               v_low = (ch4 << 24) | (ch3 << 16) | (ch2 <<
8) | ch1;

               ch1 = inputStream.read();

               ch2 = inputStream.read();

               ch3 = inputStream.read();

               ch4 = inputStream.read();

               v_high = ((ch4 << 24) | (ch3 << 16) | (ch2 <<
8) | ch1);

               return (v_high << 32) | v_low;

              Â

           }

thanks.

-------- Original Message --------

Subject:
BUG - different writing and reading of Long value

Date:
Mon, 29 Jul 2002 12:23:09 +0200

From:
Jan Kozusznik <[email protected]>

To:
[email protected]

Hello developers,

PROBLEM:

There was bug in saving value of type Long. When  I set Long attribute to
1027634400000 and later I restarted NBMDR this attribute had different value.
I found bug in IOUtils in method readLong. There was code:

      case T_LONG | 0x80: {

               int ch1, ch2, ch3, ch4;

               long v;

              Â

               ch1 = inputStream.read();

               ch2 = inputStream.read();

               ch3 = inputStream.read();

               ch4 = inputStream.read();

               v = (ch4 << 24) + (ch3 << 16) + (ch2 <<
8) + ch1;

               ch1 = inputStream.read();

               ch2 = inputStream.read();

               ch3 = inputStream.read();

               ch4 = inputStream.read();

               return v << 32 + ((ch4 << 24) + (ch3 <<
16) + (ch2 << 8) + ch1);

but in readLong there was code:

         outputStream.write(T_LONG | 0x80);

           outputStream.write((byte)(val & 0xff));

           outputStream.write((byte)((val & 0xff00) >>> 8));

           outputStream.write((byte)((val >>> 16) & 0xff));

           outputStream.write((byte)((val >>> 24) & 0xff));

           outputStream.write((byte)((val >>> 32) & 0xff));

           outputStream.write((byte)((val >>> 40) & 0xff));

           outputStream.write((byte)((val >>> 48) & 0xff));

           outputStream.write((byte)((val >>> 56) & 0xff));

As you can see lower 32-bits were writted as first ones and upper 32-bits
as second. But reading was reversed.

SOLUTION:

put in method readLong new code:

      case T_LONG | 0x80: {

            int ch1, ch2, ch3, ch4;

               long v_low,v_high;

               //add by kozusznikj

               ch1 = inputStream.read();

               ch2 = inputStream.read();

               ch3 = inputStream.read();

               ch4 = inputStream.read();

               v_low = (ch4 << 24) + (ch3 << 16) + (ch2 <<
8) + ch1;

               ch1 = inputStream.read();

               ch2 = inputStream.read();

               ch3 = inputStream.read();

               ch4 = inputStream.read();

               v_high = ((ch4 << 24) + (ch3 << 16) + (ch2 <<
8) + ch1);

               return (v_high << 32) + v_low;

Jan Kozusznik

Disnet Software,a.s.

--
mej se fajn
-----------
HonzaK.
:wq