From: Junio C Hamano <gitster@pobox.com>
To: Michael Haggerty <mhagger@alum.mit.edu>
Cc: "David Turner" <dturner@twopensource.com>,
git@vger.kernel.org, "Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>,
"Jeff King" <peff@peff.net>,
"Ramsay Jones" <ramsay@ramsayjones.plus.com>
Subject: Re: [PATCH 15/29] ref_transaction_create(): disallow recursive pruning
Date: Fri, 29 Apr 2016 01:19:03 -0700 [thread overview]
Message-ID: <xmqq4mak3k08.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <5723059C.5080406@alum.mit.edu> (Michael Haggerty's message of "Fri, 29 Apr 2016 08:56:28 +0200")
Michael Haggerty <mhagger@alum.mit.edu> writes:
> But I think it would be cleaner to achieve that goal with the following
> change:
>
> diff --git a/refs.c b/refs.c
> index 5dc2473..1d4c12a 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -790,8 +790,10 @@ int ref_transaction_update(struct ref_transaction
> *transaction,
> if (transaction->state != REF_TRANSACTION_OPEN)
> die("BUG: update called for transaction that is not open");
>
> - if ((flags & REF_ISPRUNING) && !(flags & REF_NODEREF))
> - die("BUG: REF_ISPRUNING set without REF_NODEREF");
> + if (flags & REF_ISPRUNING) {
> + /* Pruning is always non-recursive */
> + flags |= REF_NODEREF;
> + }
>
> if (new_sha1 && !is_null_sha1(new_sha1) &&
> check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
> diff --git a/refs/files-backend.c b/refs/files-backend.c
> index 8fcbd7d..9faf17c 100644
> --- a/refs/files-backend.c
> +++ b/refs/files-backend.c
> @@ -2116,7 +2116,7 @@ static void prune_ref(struct ref_to_prune *r)
> transaction = ref_transaction_begin(&err);
> if (!transaction ||
> ref_transaction_delete(transaction, r->name, r->sha1,
> - REF_ISPRUNING | REF_NODEREF, NULL, &err) ||
> + REF_ISPRUNING, NULL, &err) ||
> ref_transaction_commit(transaction, &err)) {
> ref_transaction_free(transaction);
> error("%s", err.buf);
> diff --git a/refs/refs-internal.h b/refs/refs-internal.h
> index 37a1a37..704eea7 100644
> --- a/refs/refs-internal.h
> +++ b/refs/refs-internal.h
> @@ -15,7 +15,7 @@
>
> /*
> * Used as a flag in ref_update::flags when a loose ref is being
> - * pruned.
> + * pruned. This flag implies REF_NODEREF.
> */
> #define REF_ISPRUNING 0x04
>
>
> Note that patch "add_update(): initialize the whole ref_update" should
> then be adjusted to do the flag-tweak in the add_update() function.
> ...
> If there are no objections, I will implement these changes in v2.
One worrysome point the above approach leaves is that nothing
guarantees that nobody in the codepath from the callsite of
ref-transaction-delete to ref-transaction-update looks at the flag
and acts differently depending on REF_NODEREF bit. During that
time, REF_ISPRUNING call would not trigger (flag & REF_NODEREF)
check, because "pruning implies no-deref" is done only after you
reach transaction-update (i.e. the code you added in the first
hunk), but any code after that "implie no-deref" happens will see
REF_NODEREF bit in the flag word.
As long as you can add some mechanism to make that a non-issue, I am
fine with that approach.
Thanks.
next prev parent reply other threads:[~2016-04-29 8:19 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-27 16:57 [PATCH 00/29] Yet more preparation for reference backends Michael Haggerty
2016-04-27 16:57 ` [PATCH 01/29] safe_create_leading_directories(): improve docstring Michael Haggerty
2016-04-27 16:57 ` [PATCH 02/29] remove_dir_recursively(): add docstring Michael Haggerty
2016-04-27 16:57 ` [PATCH 03/29] refname_is_safe(): use skip_prefix() Michael Haggerty
2016-04-27 16:57 ` [PATCH 04/29] refname_is_safe(): don't allow the empty string Michael Haggerty
2016-04-27 16:57 ` [PATCH 05/29] refname_is_safe(): insist that the refname already be normalized Michael Haggerty
2016-04-27 17:59 ` Junio C Hamano
2016-04-27 20:10 ` David Turner
2016-04-27 20:15 ` Jeff King
2016-04-27 20:34 ` David Turner
2016-04-27 20:37 ` Jeff King
2016-04-27 22:19 ` Jeff King
2016-04-28 17:44 ` David Turner
2016-04-27 16:57 ` [PATCH 06/29] commit_ref_update(): write error message to *err, not stderr Michael Haggerty
2016-04-27 16:57 ` [PATCH 07/29] rename_ref(): remove unneeded local variable Michael Haggerty
2016-04-27 16:57 ` [PATCH 08/29] ref_transaction_commit(): remove local variable n Michael Haggerty
2016-04-27 18:16 ` Junio C Hamano
2016-04-27 20:45 ` Junio C Hamano
2016-04-27 16:57 ` [PATCH 09/29] read_raw_ref(): rename flags argument to type Michael Haggerty
2016-04-27 16:57 ` [PATCH 10/29] read_raw_ref(): clear *type at start of function Michael Haggerty
2016-04-27 16:57 ` [PATCH 11/29] read_raw_ref(): rename symref argument to referent Michael Haggerty
2016-04-27 16:57 ` [PATCH 12/29] read_raw_ref(): improve docstring Michael Haggerty
2016-04-27 18:31 ` Junio C Hamano
2016-04-27 16:57 ` [PATCH 13/29] lock_ref_sha1_basic(): remove unneeded local variable Michael Haggerty
2016-04-27 16:57 ` [PATCH 14/29] refs: make error messages more consistent Michael Haggerty
2016-04-27 16:57 ` [PATCH 15/29] ref_transaction_create(): disallow recursive pruning Michael Haggerty
2016-04-27 18:47 ` Junio C Hamano
2016-04-27 20:23 ` David Turner
2016-04-27 20:45 ` Junio C Hamano
2016-04-27 21:15 ` Junio C Hamano
2016-04-28 17:48 ` David Turner
2016-04-28 20:15 ` Junio C Hamano
2016-04-29 6:56 ` Michael Haggerty
2016-04-29 8:19 ` Junio C Hamano [this message]
2016-04-29 8:41 ` Junio C Hamano
2016-04-29 14:29 ` Michael Haggerty
2016-04-27 16:57 ` [PATCH 16/29] ref_transaction_commit(): correctly report close_ref() failure Michael Haggerty
2016-04-27 16:57 ` [PATCH 17/29] delete_branches(): use resolve_refdup() Michael Haggerty
2016-04-27 16:57 ` [PATCH 18/29] refs: allow log-only updates Michael Haggerty
2016-04-27 16:57 ` [PATCH 19/29] refs: don't dereference on rename Michael Haggerty
2016-04-27 18:55 ` Junio C Hamano
2016-04-29 7:38 ` Michael Haggerty
2016-04-29 8:53 ` Junio C Hamano
2016-04-29 10:57 ` Michael Haggerty
2016-04-29 12:12 ` Jeff King
2016-04-29 13:55 ` Michael Haggerty
2016-04-29 14:08 ` Jeff King
2016-04-29 15:29 ` Junio C Hamano
2016-04-29 23:21 ` David Turner
2016-04-30 3:48 ` Michael Haggerty
2016-05-02 17:55 ` Junio C Hamano
2016-04-27 16:57 ` [PATCH 20/29] verify_refname_available(): adjust constness in declaration Michael Haggerty
2016-04-27 16:57 ` [PATCH 21/29] add_update(): initialize the whole ref_update Michael Haggerty
2016-04-27 16:57 ` [PATCH 22/29] lock_ref_for_update(): new function Michael Haggerty
2016-04-27 16:57 ` [PATCH 23/29] unlock_ref(): move definition higher in the file Michael Haggerty
2016-04-27 16:57 ` [PATCH 24/29] ref_transaction_update(): check refname_is_safe() at a minimum Michael Haggerty
2016-04-27 20:14 ` Junio C Hamano
2016-04-29 7:42 ` Michael Haggerty
2016-04-29 8:53 ` Junio C Hamano
2016-04-27 16:57 ` [PATCH 25/29] refs: resolve symbolic refs first Michael Haggerty
2016-04-28 23:40 ` David Turner
2016-04-29 9:51 ` Michael Haggerty
2016-04-29 23:14 ` David Turner
2016-05-02 18:06 ` Junio C Hamano
2016-04-27 16:57 ` [PATCH 26/29] lock_ref_for_update(): don't re-read non-symbolic references Michael Haggerty
2016-04-27 16:57 ` [PATCH 27/29] lock_ref_for_update(): don't resolve symrefs Michael Haggerty
2016-04-27 16:57 ` [PATCH 28/29] commit_ref_update(): remove the flags parameter Michael Haggerty
2016-04-27 16:57 ` [PATCH 29/29] lock_ref_sha1_basic(): only handle REF_NODEREF mode Michael Haggerty
2016-04-29 15:43 ` Junio C Hamano
2016-04-29 1:14 ` [PATCH 00/29] Yet more preparation for reference backends David Turner
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