From: Junio C Hamano <gitster@pobox.com>
Date: Thu, 15 May 2008 20:21:11 GMT
Subject: Re: How can I tell if a SHA1 is a submodule reference?
Message-ID: <7vabirgvyg.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <7F242E8F-13CF-4BE5-B3E6-85F285391658@ohloh.net>

Robin Luckey <robin@ohloh.net> writes:

> I am parsing the output of git-diff-tree to create some code analysis
> reports.
>
> When a user adds a submodule to a repository, git-diff-tree reports
> the SHA1 of the commit from the submodule.
>
> However, if I subsequently try to pass this SHA1 to git-cat-file, or
> indeed any other git command I have tried, I receive an error:
>
> error: unable to find b0f8c354b142e27333abd0f175544b71a0cc444e
> fatal: Not a valid object name b0f8c354b142e27333abd0f175544b71a0cc444e
>
> This makes sense to me, since these objects are not stored locally;
> they are stored in the submodule repository.
>
> However, is there a simple and reliable way for me to know which SHA1
> hashes refer to such submodule objects? I'd like to simply ignore them.

I presume you are reading "diff-tree --raw" format output.  The mode bits
for submodules (aka gitlinks) are 160000, as opposed to either 100644 or
100755 for regular files and 120000 for symbolic links.