Re: [Boost-users] boost iostreams zlib_compressor not compatible with zlib.NET

Subject: Re: [Boost-users] boost iostreams zlib_compressor not compatible with zlib.NET
From: OvermindDL1 (overminddl1_at_[hidden])
Date: 2010-05-15 21:40:00

On Wed, May 12, 2010 at 3:54 PM, Johan Ditmar <johanditmar_at_[hidden]> wrote:
> Hello,
>
> I would like to send compressed data between my C# to a C++ application in
> ZLIB format. In C++, I use the iostreams::zlib_compressor/zlib_decompressor.
> In C# I am currently using the ZOutputStream available in the zlib.NET
> library. First of all, when I compress the same data using both libraries,
> the results look different:
>
> 1.boost::iostreams::zlib_compressor:
>
> FF 13 49 48 00 00 01 00 01 00 00 00 63 61 60 60 F8 00 C4 C1 25 45 99 79 E9
> 23 87 04 00
>
> 2.zlib.NET (zlib.ZOutputStream):
>
> FF 13 49 48 00 00 01 00 01 00 00 00 78 9C 63 61 60 60 F8 00 C4 C1 25 45 99
> 79 E9 23 87 04 00 4F 31 63 8D
>
> (Note the 78 9C pattern that is present in zlib.NET, but not in boost).
>
> Furthermore, when I decompress data in zlib_decompressor that I compressed
> in zlib.NET, I am not able to read from the stream suggesting something is
> wrong. It does work when I try to decompress data compressed in the
> zlib_compressor.
>
> Does anybody know what is behind this incompatibility and whether there is
> an easy solution?

Have you tried opening both streams with an 'official' zlib program
and see which is correct?

Trying to decompress both of them (with and without header) gives
invalid block type errors to me when using the zlib library itself.