Re: Passing commit IDs to git-archive

[Jeff King <peff@peff.net>]

On Fri, Mar 09, 2012 at 05:14:05PM -0500, Stephen Bash wrote:

> on Mac OS 10.6.8 (obviously this is local testing, the goal is to use
> ssh remotely).  After parsing the error "no such ref" I attempted the
> same operation using master as the tree-ish and archive worked as
> expected (either specifying the path separately or using the colon
> syntax to reference the tree directly).  Is there a reason git-archive
> requires a named ref rather than just a commit (or tree) ID?

Yes; generally git repositories do not allow clients to access arbitrary
sha1s. Instead, they require that the requested objects be accessible by
a ref.

git-archive was not properly enforcing this, and was changed recently to
allow only refs by name, as well as sub-trees of refs (e.g.,
HEAD:subdir/). That means we do disallow an arbitrary commit or tree
sha1, even if it is reachable from the advertised refs.

> would it be difficult to patch git-upload-archive to use the IDs?  I
> could use tags for the ref, but in my case would result in almost
> every commit being a tag which seems wasteful.

Doing it right is a bit expensive, because in the general case (somebody
requested a tree sha1), we would need to traverse every tree of every
commit to see if it is reachable.

We could potentially implement a more restricted set of rules, allowing
"<commit>:<subdir>" and checking that <commit> is reachable.  That would
disallow an arbitrary tree sha1, but I suspect it would cover the common
use case (i.e., you want to get the tree, or even a subtree, of a
particular revision).

-Peff