From: Mark Brown <broonie@sirena.org.uk>
Date: Tue, 27 Jan 2009 13:14:04 GMT
Subject: Re: Valgrind updates
Message-ID: <20090127131404.GA11870@sirena.org.uk>
In-Reply-To: <alpine.DEB.1.00.0901270512171.14855@racer>

On Tue, Jan 27, 2009 at 05:26:34AM +0100, Johannes Schindelin wrote:

> I suspected that zlib does something "cute" with alignments, i.e. that it 
> writes a possibly odd number of bytes, but then rounds up the buffer to 
> the next multiple of two of four bytes.

I don't recall anything along those lines in zlib but it does generate
warnings with valgrind which require overrides - it has at least one
unrolled loop which roll on beyond initialised memory (but keep within
memory that zlib knows it has allocated).  It rolls back the results of
the loop before producing output, but it's possible that some unused
bits in the stream may be derived from the results.