Re: [RFC/PATCH 0/4] real reachability checks for upload-archive

Jeff King [off-list ref] writes:

On Wed, Jun 05, 2013 at 12:38:23PM -0400, Jeff King wrote:

quoted

  2. Actually do a reachability check. Doing a full object check to
     allow fetching an arbitrary tree by sha1 is probably prohibitively
     expensive[2], but we could allow the form "<commit>[:<path>]", check
     that "<commit>" is reachable, and then allow arbitrary paths within
     it.

Thinking on this more, the full reachability check is no worse than what
a clone has to do to fetch the full repository. Here's a series that
does the full check. I'm not entirely happy with the performance,
though; details are in patch 3.

For some repository-servers, it may be OK to enable this by default,
but I suspect it would be better to have at least an opt-out server
configuration.

I think I'd be tempted to just go the more limiting "commit is
reachable" route, instead, which would solve your case (and most sane
cases).

Yes, I think that is a reasonable thing to do.  After all, as you
noted in 4/4, you cannot ask for a single blob, and not being able
to ask for a single tree is not much different.

  [1/4]: clear parsed flag when we free tree buffers
  [2/4]: upload-archive: restrict remote objects with reachability check
  [3/4]: list-objects: optimize "revs->blob_objects = 0" case
  [4/4]: archive: ignore blob objects when checking reachability

-Peff