Nullpointer Exception when <Message>.parseFrom(byte [])

[jim horng]

Hi all,

It occur to me that when I'm trying to parse any of the binary data
files I listed below,
using <Message>.parseFrom(byte []). it said nullpointer exception.

To my best knowledge, I think when the raw bytes does not contain
required field, protobuf API should return invalidprotobufexception
when using .parseFrom(), or at least it will throw
uninitializeprotobuf exception when .build().
so that client will know what happen and have change to handle them
correctly.
But if it return nullpointerexception, it will be hard to know what
really happen, it can only be roughly assumed message parsing is
failed.
My goal is just to determine if the received binary files is an
expected protobuf message or not.

Please kindly advise or if this is work as design under some reason.
Thanks a lot !



<code snippet>
String filepath = "np1.pb";
byte[] file_byteary = getBytesFromFile(new File(filepath));

xxx.Connection.Builder conn_builder =
xxx.Connection.newBuilder();
xxx.Connection MB_tmp =
xxx.Connection.parseFrom(file_byteary);
conn_builder.mergeFrom(MB_tmp);
System.out.println("is init?" + conn_builder.isInitialized());
assertTrue(conn_builder.build() != null);
</code snippet>

* test data
https://docs.google.com/leaf?id=0B9CkCymjWlZLNWMyMGNiNjEtMDJiZi00NDY0LTgzMWUtMjI1N2I0MWVhNjlh&hl=en

[Kenton Varda]

The file you attached is not useful without source code.

But what would be even better is if you could provide the stack trace for the NullPointerException.  The parser should never throw NPE and I'm not aware of any bugs which cause it to throw NPE.

BTW, it's very easy for bytes which are not actually a protocol buffer to parse correctly as a protocol buffer.  The protobuf encoding is pretty dense.  So I would suggest that you instead use some sort of tagging mechanism to distinguish protobuf data from other kinds of data that you need to process.

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[jim horng]

Hi Kenton,

here are the stacktrace, i found i'm using 2.1.0

java.lang.NullPointerException

        at com.google.protobuf.UnknownFieldSet$Builder.mergeFieldFrom(UnknownFieldSet.java:422)

        at com.google.protobuf.GeneratedMessage$Builder.parseUnknownField(GeneratedMessage.java:289)

        at com.trendmicro.mist.proto.MistMessage$MessageBlock$Builder.mergeFrom(MistMessage.java:621)

        at com.trendmicro.mist.proto.MistMessage$MessageBlock$Builder.mergeFrom(MistMessage.java:602)

        at com.trendmicro.mist.proto.MistMessage$MessageBlock$Builder.mergeFrom(MistMessage.java:504)

        at com.google.protobuf.AbstractMessage$Builder.mergeFrom(AbstractMessage.java:358)

        at com.google.protobuf.AbstractMessage$Builder.mergeFrom(AbstractMessage.java:351)

        at com.trendmicro.mist.Session.runProducer(Session.java:288)

        at com.trendmicro.mist.Session.run(Session.java:805)

        at java.lang.Thread.run(Thread.java:619)

After I switch to 2.3.0, the exception become much more reasonable:
Exception in thread "main" com.google.protobuf.InvalidProtocolBufferException: Protocol message contained an invalid tag (zero).
    at com.google.protobuf.InvalidProtocolBufferException.invalidTag(InvalidProtocolBufferException.java:68)
    at com.google.protobuf.CodedInputStream.readTag(CodedInputStream.java:90)
    at test.Test$Person$Builder.mergeFrom(Test.java:279)
    at test.Test$Person$Builder.mergeFrom(Test.java:1)
    at com.google.protobuf.AbstractMessage$Builder.mergeFrom(AbstractMessage.java:244)
    at com.google.protobuf.AbstractMessage$Builder.mergeFrom(AbstractMessage.java:183)
    at com.google.protobuf.AbstractMessageLite$Builder.mergeFrom(AbstractMessageLite.java:162)
    at com.google.protobuf.AbstractMessage$Builder.mergeFrom(AbstractMessage.java:661)
    at com.google.protobuf.AbstractMessage$Builder.mergeFrom(AbstractMessage.java:183)
    at com.google.protobuf.AbstractMessageLite$Builder.mergeFrom(AbstractMessageLite.java:153)
    at com.google.protobuf.AbstractMessage$Builder.mergeFrom(AbstractMessage.java:654)
    at test.Test$Person.parseFrom(Test.java:119)
    at test.Test_pb_NPE.main(Test_pb_NPE.java:21)

thanks

--
Best Regards,
Jim(洪懷謙)

[Kenton Varda]

Indeed, this was a bug that we fixed.