Re: [PATCH 8/8] cache-tree: avoid path comparison loop when silent

From: Junio C Hamano <gitster@pobox.com>
Date: Jan 6, 2021, 08:55 UTC
Message-ID: <xmqqble2sav9.fsf@gitster.c.googlers.com>
In-Reply-To: <CABPp-BFp5=C+6B1WUarXzabo0fU4xotP5UG91-hYahCHDA6Cng@mail.gmail.com>

Elijah Newren <newren@gmail.com> writes:

Show 5 quoted lines

> Looking through that code, I come to the same conclusion, though it
> might be nice to have Junio confirm (and to explain the "if (10 <
> ++funny)" section; did that help debugging too?).   The second part of
> the loop was part of his initial commit adding the cache-tree
> extension in commit 749864627c ("Add cache-tree.", 2006-04-23)

This is not about debugging our implementation. The verification was done to protect against the on-disk index file left by broken implementations of other people. Either JGit or Dulwich (I do not recall which one) used to have such a broken sort long time ago, IIRC, and the thing is, a broken implementation can be internally consistent.

I do not think we've heard problem reports discovered by this check about other peoples' broken implementation, but a chicken-and-egg is certainly in action here. The check would have caught any new and broken implementation of Git before it got released to the wild to cause harm and that is probably we haven't heard.