[Haskell-cafe] Ongoing IHG work to improve Hackage security

[Duncan Coutts]

On Thu, 2015-04-16 at 15:14 +0200, Mikhail Glushenkov wrote:
> Hi,
> 
> On 16 April 2015 at 11:33, Duncan Coutts <duncan at well-typed.com> wrote:
> > All,
> >
> > The IHG members identified Hackage security as an important issue some
> > time ago and myself and my colleague Austin have been working on a
> > design and implementation.
> >
> > The details are in this blog post:
> >
> > http://www.well-typed.com/blog/2015/04/improving-hackage-security
> 
> Thank you, this is very exciting. But won't the post-release .cabal
> update feature interfere with "package index as an append-only log"
> concept? IIUC, right now it is implemented as a destructive update of
> the corresponding package index entry, so making the package index
> immutable will break backwards compatibility.

Yes, we can use the tar file in an append-only way while allowing
metadata updates because that's the tar file format supports that.

The tar file format was originally designed for tape drives where
rewinding and updating old entries was far too expensive. So the tar
file format allows appending updated file entries to the end of the
archive. Compliant tar tools (including the standard unix tools, and
cabal-install) understand this and take the last entry in the archive as
the current file content.

-- 
Duncan Coutts, Haskell Consultant
Well-Typed LLP, http://www.well-typed.com/