Duy Nguyen <pclouds@xxxxxxxxx> writes: > On Wed, Jan 20, 2016 at 1:44 AM, Junio C Hamano <gitster@xxxxxxxxx> wrote: >> Duy Nguyen <pclouds@xxxxxxxxx> writes: >> >>> I think it's the intended behavior. >> >> Yeah, pre-commit was designed for inspecting and rejecting, not for >> tweaking and munging. Perhaps "git commit" can be tightened to make >> sure that pre-commit that returns successfully did not muck with the >> working tree and the index? > > That was my impression from the docs, but then I saw this comment, > > /* > * Re-read the index as pre-commit hook could have updated it, > * and write it out as a tree. We must do this before we invoke > * the editor and after we invoke run_status above. > */ > > which comes from 2888605 (builtin-commit: fix partial-commit support - > 2007-11-18) that admits "the hook can modify it (the index)". And I > was about to update the docs, but the other way around, about updating > index and side effects. I do not think the comment is wrong per-se, but the code we have, either back then or even today, is insufficient to allow pre-commit hook that mucks with the fake index that is shown to it. Re-reading the in-core index at that point may help creating a commit whose tree matches what the hook did, but the extra change made by the hook is not ported forward in the real index that the user will use after a partial commit (and there is no easy way to do so cleanly--the change the hook makes may even overlap the change in the real index that are added but left uncommitted, and you would end up needing to run a threeway merge). The only sensible thing we can do at that point in the code after re-reading the index is to make sure that hasn't been changed by the pre-commit hook and complain loudly to die if we find it modified, I think. -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html