On Feb 1, 2008, at 12:33 PM, Alberto Bacchelli wrote:
> Hi,
>
> trying some automatic test case generator on the code, I found that
> there is a bug in freenet.support.BitArray.
> It is not a problem in the Freenet code, but it seems a Java problem
> (maybe only with the VM version I am using which is Java(TM) SE
> Runtime
> Environment (build 1.6.0_03-b05) ).
>
> if you run this test:
>
> public void testConstructorThrowsEOFException1() throws Throwable {
> DataInputStream dis = new DataInputStream(new
> ByteArrayInputStream("testString".getBytes()));
> try {
> new BitArray(dis);
> fail("Expected EOFException to be thrown");
> } catch (EOFException ex) {
> assertEquals("ex.getClass()", EOFException.class,
> ex.getClass());
> assertThrownBy(DataInputStream.class, ex);
> assertEquals("dis.available()", 0, dis.available());
> }
> }
>
> you will probably get a java.lang.OutOfMemoryError.
>
> This is caused by a bad value returned by readInt() in the following
> code:
>
>
> public BitArray(DataInputStream dis) throws IOException {
> _size = dis.readInt();
> _bits = new byte[(_size / 8) + (_size % 8 == 0 ? 0 : 1)];
> dis.readFully(_bits);
> }
>
> the simpliest way to solve this issue imho is to find a way to avoid
> using readInt().
>
> Sback
I'm not really sure this is so much a bug as garbage-in-garbage-out.
By the code provided, the size for the bitarray is given first, then
the raw data; it just so happens that when you translate the first
several bytes of "testString" into an integer, it comes out to be very
large number (more bytes than are available for allocation). Note that
there *is* a legitimate bitarray data stream which will begin with
"testString".asBytes(), it is probably just too large for practical use.
--
Robert Hailey
