Re: suggested feature: someone mails me a blob, git please tell me what it is

From: Nicolas Pitre <nico@cam.org>
Date: Feb 16, 2007, 16:48 UTC
Message-ID: <alpine.LRH.0.82.0702161136460.18370@xanadu.home>
In-Reply-To: <3c6c07c20702160823j316c52f4pe4cf5ca8a882e194@mail.gmail.com>

On Fri, 16 Feb 2007, Mike Coleman wrote:

Show 9 quoted lines

> Here's a suggestion for a git feature, if git doesn't already have it.
> Since git generally doesn't use RCS-style keyword cookies (like
> "$Id$"), it'd be nice to have some other way to identify an installed
> file.  Perhaps you'd want to know exactly what rev a user is running,
> for example.
> 
> It seems like it should be fairly easy, given a blob (the file), for
> git to describe what it knows about it.  For example, it could provide
> a list of commits that it's a part of, etc.

That is possible, but would be expensive similar to git-fsck-objects. All objects for each commit would need to be searched for the matching sha1.

> It'd be *really* nice if only the output of the sha1sum command on the 
> blob were needed.  (I can't recall exactly how git's blob SHA1's are 
> computed--maybe this isn't feasible.)

GIT adds a header of its own before object data. You therefore need to use git-hash-object not sha1sum to get the right sha1 value.

Nicolas