The first 8 bytes is some kind of header.
the next two bytes are varint tag with field number 1 and interger value =
0
next 6 bytes is also varint tag with field number 2 and value = {five byes}
next 2 bytes says it is a string or byte array with with 6 bytes long. :)
On Tuesday, May 19, 2015 at 11:54:01 PM UTC+2, Jim Muchow wrote:
> I sent a question yesterday, but I don't see it as having been posted,
> much less
> responded to. My apologies for the redundancy if my original message is in
> some
> queue somewhere.
>
> **********
>
> I'm trying to determine the utility of Valgrind in an app. The app uses
> protocol buffers.
>
> I am seeing a message from Valgrind
>
> Syscall param write(buf) points to uninitialised byte(s)
>
> with the following info
>
> Address 0x11c7fa02 is 2 bytes inside a block of size 8,192 alloc'd
>
> At first, I thought it might be one of the fields in a message declared
> optional, but
> when I filled out the field, I got the same warning. In the process of
> looking into this
> more closely I was able to dump the buffer:
>
> 0x00 0x01 0xc1 0x09 0x00 0x00 0x00 0x10 <---- secret,
> pre-header?
> 0x08 0x00 0x10 0xa5 0xcb 0x96 0xad 0x0a
> 0x1a 0x06 0x61 0x70 0x61 0x63 0x68 0x65
>
> The latter 16 bytes are the message proper with three fields and I
> understand how
> they are created and interpreted from the Encoding spec (very helpful). It
> is the first
> eight bytes I don't understand.
>
> These first bytes are almost like a secret pre-header. It looks to me as
> if the last four
> bytes are a 32-bit length field. The number matches in this case and in
> the other case in
> which the optional field was left unset. I can't figure what the first
> four bytes indicate. In
> particular, the bytes 0xc1 and 0x09, which would start the area of the
> supposedly
> uninitialized bytes.
>
> Is there somewhere in the code I can look to see how this pre-header is
> created. Or I
> would be happy to research this myself if some documentation exists, but I
> don't know
> where to start looking.
>
> Thanks for any help,
> jdm
>
>
--
You received this message because you are subscribed to the Google Groups
"Protocol Buffers" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/protobuf.
For more options, visit https://groups.google.com/d/optout.
