Re: [Boost-users] Another decompression issue?

Subject: Re: [Boost-users] Another decompression issue?
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2010-11-27 14:03:42

AMDG

On 10/19/2010 5:29 AM, Bryan wrote:
> I'm using Boost 1.43 and I've run across a situation where I'm getting 
> unexpected results when reading the uncompressed stream.  I originally 
> thought that it was an issue with my data format interpretation, but 
> it turns out that something seems to be consuming a character from the 
> input stream.  Here's a sample of reading the stream a character at a 
> time:
> cur = 80, next = 80
> cur = 80, next = 38
> cur = 38, next = 8c
> cur = 8c, next = c
> cur = b4, next = db <--- Cur != previous next
> cur = db, next = 1
> cur = 1, next = 1
> cur = 1, next = dd
>
> This debugging output shows the discontinuity in the stream.  The code 
> is pretty simple:
>
>     boost::iostreams::filtering_istream instream;
>     std::fstream infile;
>     uint8_t d;
>     instream.push(boost::iostreams::bzip2_decompressor());
>     infile.open("file.bz2", std::ios::binary|std::ios::in);
>     instream.push(infile);
>
>     while (true){
>         instream >> d;
>         fprintf(stderr, "cur = %x, next = %x\n", d, instream.peek());
>     }
>
> Reading a large chunk of data from the stream via read() does not have 
> the same issue.
>
> I see that there are a few changes for compression in 1.44 [Fix 
> several issues with compression and decompression (#2318, #4091, 
> #3348, #2783, #1579, #3853). ] but it's unclear if this is one of them.

This looks like a serious problem.  Can you file a trac ticket at
http://svn.boost.org, including a complete test case?

In Christ,
Steven Watanabe