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I have a simple test case producing a sure ArrayOutOfBoundException in jzlib 1.0.7 depending on the data subsequently written to one and the same instance of ZOutputStream.

Stacktrace:

java.lang.ArrayIndexOutOfBoundsException: 587
    at com.jcraft.jzlib.Tree.d_code(Tree.java:149)
    at com.jcraft.jzlib.Deflate.compress_block(Deflate.java:691)
    at com.jcraft.jzlib.Deflate._tr_flush_block(Deflate.java:897)
    at com.jcraft.jzlib.Deflate.flush_block_only(Deflate.java:772)
    at com.jcraft.jzlib.Deflate.deflate_slow(Deflate.java:1195)
    at com.jcraft.jzlib.Deflate.deflate(Deflate.java:1567)
    at com.jcraft.jzlib.ZStream.deflate(ZStream.java:133)
    at com.jcraft.jzlib.ZOutputStream.write(ZOutputStream.java:102)
    at com.jcraft.jzlib.JZLibTestCase.main(JZLibTestCase.java:51)
       at JZLibTestCase.main(JZLibTestCase.java:28)

The problem occurs very rarely and depends on the data subsequentially written to an open ZOutputStream from jzlib.

Do you have a hint how to fix this? Have you ever heard of this?

René
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2 Answers2

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Near as I can tell you might've found a bug with JZlib. While searching around I came across other places that have your post with attached source and data files. It does not appear that you're doing anything wrong. You should be able to stream any sequence of bytes to ZOutputStream.

Is there a particular reason you're using JZlib? The two main reasons I understand to use it are support for Z_PARTIAL_FLUSH mode and licensing. If you don't need that flush mode and you're using the Oracle JVM, you should be just fine with the included DeflaterOutputStream. Substituting it in your code for ZOuputStream works without an exception.

WhiteFang34
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  • Yes, is it clearly a bug in jzlib depending on the data to be compressed, I've already reported it to JCraft. – René Apr 15 '11 at 06:47
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I haven't found a concrete reason for using jzlib asking my co-workers, but for sure there has been a bug using java.util.zip somewhen in JRE 1.4 on multi-processor systems, although no one has been able to tell me concretely which one. From that time on we have been using jzlib, which has worked good for many years. Most probably it is already fixed. Nevertheless, using java.util.zip works with my simple test data in the same manner jzlib failed with, that's true.

René
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