Yeah, I think it's broken.
In reflection.py there is a line:
return decoder.Position() - content_start
I think (untested) that it should actually be:
return decoder.Position() - initial_position
I have no idea how this got past testing and I have asked the people
responsible to fix it. Surprisingly you are the first to report this, so
maybe there's a mitigating factor that makes it unusual for the bug to harm
anything. Sorry for the trouble.
On Thu, Jul 2, 2009 at 5:14 PM, Dan <danbr...@gmail.com> wrote:
>
> Hello protobuf gurus-
> I'm just getting started with the python version of protobuf, using
> v2.10. I want to store some lists of floats in a database's blob
> field. When using a nested Message structure with the "packed=true"
> option, I'm getting errors that look like this:
>
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "build/bdist.linux-i686/egg/google/protobuf/message.py", line
> 160, in ParseFromString
> File "build/bdist.linux-i686/egg/google/protobuf/reflection.py",
> line 1215, in MergeFromString
> File "build/bdist.linux-i686/egg/google/protobuf/reflection.py",
> line 1075, in _DeserializeOneEntity
> File "build/bdist.linux-i686/egg/google/protobuf/reflection.py",
> line 899, in _RecursivelyMerge
> File "build/bdist.linux-i686/egg/google/protobuf/internal/
> decoder.py", line 181, in ReadMessageInto
> google.protobuf.message.DecodeError: Submessage told to deserialize
> from 14-byte encoding, but used only 12 bytes
>
> If I use a flat (not nested) message structure, I do not get these
> errors. If I use a nested, packed=false approach, I do not get these
> errors. The error happens only when both nested and packed.
>
> Here is some code to reproduce the problem. Note that the
> deserialization seems to succeed in putting the correct values into
> the list (at least in this test), in spite of the error message.
>
> my.proto file contains:
>
> message TestNest {
> optional ListData list_data = 1;
> message ListData {
> repeated float float_packed = 1 [packed=true];
> repeated float float_notpacked = 2 [packed=false];
> repeated int32 int_packed = 3 [packed=true];
> repeated int32 int_notpacked = 4 [packed=false];
> }
> }
>
> and then I run this set of commands for each of the fields
> [float_packed, float_notpacked, int_notpacked, int_packed] and see
> that the error happens only for the two fields that use packed=true.
>
> import my_pb2
> a = my_pb2.TestNest()
> a.list_data.float_notpacked.extend([1,2,3])
> a_string = a.SerializeToString()
> a_deserialized = my_pb2.TestNest()
> a_deserialized.ParseFromString(a_string)
> str(a_deserialized)
>
> I can think of three options to proceed, 2 of which I'm able to do
> myself:
> 1) don't use the packed=true option
> 2) catch the errors and ignore them
> 3) if this is actually a bug, ask you gurus to fix the protobuf code
>
> What do you recommend?
> Dan
>
> >
>
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