NullPointerException while reading a compressed file

[MarcoBerlot]

Describe the bug
Null pointer exception being thrown while attempting to read lz4 file.

java.lang.NullPointerException
at net.jpountz.lz4.LZ4FrameInputStream.read(LZ4FrameInputStream.java:295)
at java.base/java.io.FilterInputStream.read(Unknown Source)

Expected behavior
The file should be properly uncompressed and read.

To Reproduce
Unfortunately I can't provide steps to reproduce since this has happened in our production environment. Here's the function that is reading the lz4 files

private byte[] readCompressedFile(File file) throws IOException {
        LZ4FrameInputStream gis = new LZ4FrameInputStream(new FileInputStream(file));
        ByteArrayOutputStream fos = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len;
        while ((len = gis.read(buffer)) != -1) {
            fos.write(buffer, 0, len);
        }
        fos.close();
        gis.close();
        return fos.toByteArray();
    }

System (please complete the following information):

• OS: CentOS Linux release 7.8.2003 (Core)
• Compiler: OpenJ9
• Build System [e.g. Makefile]
• Other hardware specs [e.g Core 2 duo...]

[odaira]

Thanks for reporting this. What version of lz4-java are you using?

[MarcoBerlot]

Java version: 10.0.1 (build 10.0.1+10) x 86_64
openjdk 11.0.9 2020-10-20 LTS
OpenJDK Runtime Environment 18.9 (build 11.0.9+11-LTS)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.9+11-LTS, mixed mode, sharing)

Thanks @odaira

[MarcoBerlot]

One way that I was able to reproduce this is by passing an empty file. In this case nextFrameInfo(); will return early and ByteBuffer buffer won't be initialized and when it tries to read the file it will encounter a NPE.
I believe a more explicit exception might help in this case, or make sure that the buffer gets initialized also in the case of an empty file.

[odaira]

@MarcoBerlot These are the versions of your Java runtime, but I would like to know the version of lz4-java you are using.

Java version: 10.0.1 (build 10.0.1+10) x 86_64
openjdk 11.0.9 2020-10-20 LTS
OpenJDK Runtime Environment 18.9 (build 11.0.9+11-LTS)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.9+11-LTS, mixed mode, sharing)

Doesn't your application include a jar file named lz4-java-x.y.z.jar, like lz4-java-1.7.1.jar? Then x.y.z is the version of lz4-java.

[MarcoBerlot]

@odaira sorry, I did not read it correctly. I'm using version 1.4

[odaira]

Fixed by 5e23573 and fa30b17. Thank you for your help!