[PATCH RFC aiaiai 09/11] aiaiai: add git-find-base utility for finding base commit from mbox

[Keller, Jacob E]

On Mon, 2014-03-31 at 11:46 +0300, Artem Bityutskiy wrote:
> On Thu, 2014-03-27 at 11:40 -0700, Jacob Keller wrote:
> > This patch adds a helper utility for git, git-find-base which works by
> > checking the index information provided by git-diff's output. It works
> > by parsing the mbox for diff lines, and extracting the index line. This
> > is the shortblob of the file in git's database that this patch
> > originally applied to.
> > 
> > The general flow of this perl tool is:
> > 
> > 1) Extract all the files and base blob indexes that the patch modifies,
> >    using a regular expression.
> > 2) Run git log with all arguments directly passed through
> > 3) For each commit returned by git log, check the ls-tree output for the
> >    modified file. If any of them fail to match, then this patch cannot
> >    apply cleanly to the commit.
> > 4) print the sha1sum of the first commit which passes the check blobs
> >    test.
> > 
> > This tool can be used to automatically determine if a commit can be
> > applied cleanly to a branch, and even detect which commit it should be
> > applied to. Various options passed to the log can change how much
> > detection it does.
> > 
> > If a patch series is applied, it will check each modification of a file,
> > and ensure that it could apply in sequence generating the final result.
> > This allows finding the first commit at which a series will apply. If a
> > series is not self-consistent, then git-find-base will fail to supply
> > the base commit, and may output errors regarding the nature of the
> > inconsistency.
> > 
> > The primary intention for this tool will be an example hook for aiaiai
> > which automatically detects which project a patch was originally based
> > on.
> 
> Would it please be possible to add '-h'/'--help' option which would
> print something like the commit message explaining the purpose and use
> of this script. Or at least put this kind of expanded comment to the
> script. This way people won't have to dig git logs to grasp the general
> idea.
> 

Yes, I think that would be possible.

Thanks,
Jake