Re: [PATCH v3] sparse index: fix use-after-free bug in cache_tree_verify()

Hi Junio

On 08/10/2021 20:57, Junio C Hamano wrote:

Phillip Wood [off-list ref] writes:

quoted

On 07/10/2021 22:23, Junio C Hamano wrote:

quoted

"Phillip Wood via GitGitGadget" [off-list ref] writes:

quoted

       * Fixed the spelling of Stolee's name (sorry Stolee)
       * Added "-q" to the test to prevent a failure on Microsoft's fork[1]
           [1]
      https://lore.kernel.org/git/ebbe8616-0863-812b-e112-103680f7298b@gmail.com/ (local)

I've seen the exchange, but ...

quoted

-	for OPERATION in "merge -m merge" cherry-pick rebase
+	for OPERATION in "merge -m merge" cherry-pick "rebase --apply -q" "rebase --merge"
   	do

... it looks too strange that only one of them requires a "--quiet"
option.  Is it a possibility to get whoever's fork corrected so that
it behaves sensibly without requiring the "-q" option only for the
particular rebase backend?

The issue is caused by a patch that Microsoft is carrying that stops
apply from creating paths with the skip-worktree bit set. As they're
upstreaming their sparse index and checkout work I expect it will show
up on the list sooner or later. I agree the "-q" is odd and it also
means the test is weaker but I'm not sure what else we can do.

Perhaps passing "-q" to the other variant of "rebase" would make it
clear that (1) we do not want to worry about traces involved in the
verbose message generation and (2) there is nothing fishy going on
in only one of the "rebase" backends.

I'm not sure about that. There are really three levels of output from 
rebase - quiet, normal and verbose. I think passing "-q" suppresses 
virtually all the output - there is no indication of which commits have 
been picked. As test appears to be comparing the output of the command 
for the sparse and non-spare case as a proxy for "it behaves the same 
for sparse and non-sparse checkouts/indexes" passing "-q" to rebase 
weakens the test considerably. Stolee indicated [1] that he is happy for 
us to drop the "-q" for the "--apply" case so I'd be inclined to go back 
to your corrected version of V2.

Best Wishes

Phillip

[1] 
https://lore.kernel.org/git/e281c2e2-2044-1a11-e2bc-5ab3ee92c300@gmail.com/ (local)