[PATCH] restore: invalidate cache-tree when removing entries with --staged
- From
Jeff King <peff@peff.net>
- Date
- Jan 8, 2020, 11:43 UTC
- Message-ID
- <20200108114344.GA3380580@coredump.intra.peff.net>
- In-Reply-To
- <20200108104008.GA2207365@coredump.intra.peff.net>
On Wed, Jan 08, 2020 at 05:40:08AM -0500, Jeff King wrote:
Show 6 quoted lines
> So there seem to be at least two bugs: > > - git-restore doesn't properly invalidate the cache-tree > > - the index-reading code is not careful enough about bogus cache-trees, > and may segfault
Here's a fix for the first one. I'm adding Junio to the cc as an expert in index and cache-tree issues. I'm pretty sure this is the correct fix, but I have some lingering questions below.
I'm not planning on working on the second one immediately. Between this and Emily's patch from yesterday, I have a feeling that the index code could use an audit to be a bit more careful about handling bogus on-disk data.
-- >8 -- Subject: restore: invalidate cache-tree when removing entries with --staged
When "git restore --staged <path>" removes a path that's in the index, it marks the entry with CE_REMOVE, but we don't do anything to invalidate the cache-tree. In the non-staged case, we end up in checkout_worktree(), which calls remove_marked_cache_entries(). That actually drops the entries from the index, as well as invalidating the cache-tree and untracked-cache.
But with --staged, we never call checkout_worktree(), and the CE_REMOVE entries remain. Interestingly, they are dropped when we write out the index, but that means the resulting index is inconsistent: its cache-tree will not match the actual entries, and running "git commit" immediately after will create the wrong tree.
We can solve this by calling remove_marked_cache_entries() ourselves before writing out the index. Note that we can't just hoist it out of checkout_worktree(); that function needs to iterate over the CE_REMOVE entries (to drop their matching worktree files) before removing them.
One curiosity about the test: without this patch, it actually triggers a BUG() when running git-restore:
BUG: cache-tree.c:810: new1 with flags 0x4420000 should not be in cache-tree
But in the original problem report, which used a similar recipe, git-restore actually creates the bogus index (and the commit is created with the wrong tree). I'm not sure why the test here behaves differently than my out-of-suite reproduction, but what's here should catch either symptom (and the fix corrects both cases).
Reported-by: Torsten Krah <krah.tm@gmail.com> Signed-off-by: Jeff King <peff@peff.net> --- So I'm mildly puzzled about the BUG thing above. But also: it seems really weird that do_write_index() will drop CE_REMOVE entries as it writes, but not invalidate the cache-tree (or the untracked-cache, which AFAICT is probably similarly affected). Should it be doing that invalidation? Or should it be a BUG() to write out an index without having done remove_marked_cache_entries()?
builtin/checkout.c | 2 ++ t/t2070-restore.sh | 18 ++++++++++++++++++ 2 files changed, 20 insertions(+)
diff --git a/builtin/checkout.c b/builtin/checkout.c index b52c490c8f..18ef5fb975 100644 --- a/builtin/checkout.c +++ b/builtin/checkout.c @@ -524,6 +524,8 @@ static int checkout_paths(const struct checkout_opts *opts, /* Now we are committed to check them out */ if (opts->checkout_worktree) errs |= checkout_worktree(opts); + else + remove_marked_cache_entries(&the_index, 1); /* * Allow updating the index when checking out from the index. diff --git a/t/t2070-restore.sh b/t/t2070-restore.sh index 21c3f84459..06a5976143 100755 --- a/t/t2070-restore.sh +++ b/t/t2070-restore.sh @@ -96,6 +96,7 @@ test_expect_success 'restore --ignore-unmerged ignores unmerged entries' ' ' test_expect_success 'restore --staged adds deleted intent-to-add file back to index' ' + test_when_finished git reset --hard && echo "nonempty" >nonempty && >empty && git add nonempty empty && @@ -106,4 +107,21 @@ test_expect_success 'restore --staged adds deleted intent-to-add file back to in git diff --cached --exit-code ' +test_expect_success 'restore --staged invalidates cache tree for deletions' ' + test_when_finished git reset --hard && + >new1 && + >new2 && + git add new1 new2 && + + # It is important to commit and then reset here, so that the index + # contains a valid cache-tree for the "both" tree. + git commit -m both && + git reset --soft HEAD^ && + + git restore --staged new1 && + git commit -m "just new2" && + git rev-parse HEAD:new2 && + test_must_fail git rev-parse HEAD:new1 +' + test_done
-- 2.25.0.rc1.622.g8cfac75bdd