[COMPRESS-309] BZip2CompressorInputStream return value wrong when told to read to a full buffer.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.4.1, 1.9
• Fix Version/s: 1.10
• Component/s: Compressors
• Labels: bzip2 compression
• Assignee: Unassigned
• Reporter: Nathan Kronenfeld
• Created: 18/Feb/15 17:22
• Updated: 20/Feb/15 16:18
• Resolved: 20/Feb/15 16:18

Description

BZip2CompressorInputStream.read(buffer, offset, length) returns -1 when given an offset equal to the length of the buffer.

This indicates, not that the buffer was full, but that the stream was finished.

It seems like a pretty stupid thing to do - but I'm getting this when trying to use Kryo serialization (which is probably a bug on their part, too), so it does occur and has negative affects.

Here's a JUnit test that shows the problem specifically:

	@Test
	public void testApacheCommonsBZipUncompression () throws Exception {
		// Create a big random piece of data
		byte[] rawData = new byte[1048576];
		for (int i=0; i<rawData.length; ++i) {
			rawData[i] = (byte) Math.floor(Math.random()*256);
		}

		// Compress it
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		BZip2CompressorOutputStream bzipOut = new BZip2CompressorOutputStream(baos);
		bzipOut.write(rawData);
		bzipOut.flush();
		bzipOut.close();
		baos.flush();
		baos.close();

		// Try to read it back in
		ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
		BZip2CompressorInputStream bzipIn = new BZip2CompressorInputStream(bais);
		byte[] buffer = new byte[1024];
		// Works fine
		Assert.assertEquals(1024, bzipIn.read(buffer, 0, 1024));
		// Fails, returns -1 (indicating the stream is complete rather than that the buffer 
		// was full)
		Assert.assertEquals(0, bzipIn.read(buffer, 1024, 0));
		// But if you change the above expected value to -1, the following line still works
		Assert.assertEquals(1024, bzipIn.read(buffer, 0, 1024));
		bzipIn.close();
	}