From: "Martin Ågren" <martin.agren@gmail.com>
To: Michael Haggerty <mhagger@alum.mit.edu>
Cc: Junio C Hamano <gitster@pobox.com>,
Eric Sunshine <sunshine@sunshineco.com>,
Git Mailing List <git@vger.kernel.org>,
Thomas Gummerer <t.gummerer@gmail.com>
Subject: Re: [PATCH v2 3/9] ref_transaction_update(): die on disallowed flags
Date: Tue, 7 Nov 2017 21:53:26 +0100 [thread overview]
Message-ID: <CAN0heSpOpfCmf8k8kZz1L-1qb-5mDHMLbQYaLPKE=twOhgyi8A@mail.gmail.com> (raw)
In-Reply-To: <10901328af1e6e04e8c7c7b39977ec85f6c58142.1509870243.git.mhagger@alum.mit.edu>
On 5 November 2017 at 09:42, Michael Haggerty <mhagger@alum.mit.edu> wrote:
> Callers shouldn't be passing disallowed flags into
> `ref_transaction_update()`. So instead of masking them off, treat it
> as a bug if any are set.
>
> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
> ---
> refs.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/refs.c b/refs.c
> index 62a7621025..7c1e206e08 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -940,7 +940,8 @@ int ref_transaction_update(struct ref_transaction *transaction,
> return -1;
> }
>
> - flags &= REF_TRANSACTION_UPDATE_ALLOWED_FLAGS;
> + if (flags & ~REF_TRANSACTION_UPDATE_ALLOWED_FLAGS)
> + BUG("illegal flags 0x%x passed to ref_transaction_update()", flags);
>
> flags |= (new_oid ? REF_HAVE_NEW : 0) | (old_oid ? REF_HAVE_OLD : 0);
The masking out is for sanity, but also partly to squelch a
compiler-warning. Thomas reported [1] that dieing does not make the
warning go away, but that masking out does. Of course, avoiding warnings
is not the ultimate goal, and -Wnonnull is not part of DEVELOPER_CFLAGS.
Thomas reluctantly suggested that one could do your check and then do
the masking...
Maybe it would be worth a note in the commit message. But blaming these
lines quickly leads to c788c54cd (refs: strip out not allowed flags from
ref_transaction_update, 2017-09-12), which describes this already. OTOH,
since the warning does not hit these lines, but a bit below, maybe it's
even worth a comment in the code.
I'm not saying we should sprinkle comments for each warning we hit...
Anyway, those were the thoughts than ran through my mind.
[1] https://public-inbox.org/git/20170924204541.GA2853@hank/
next prev parent reply other threads:[~2017-11-07 20:53 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-05 8:42 [PATCH v2 0/9] Tidy up the constants related to ref_update::flags Michael Haggerty
2017-11-05 8:42 ` [PATCH v2 1/9] files_transaction_prepare(): don't leak flags to packed transaction Michael Haggerty
2017-11-05 8:42 ` [PATCH v2 2/9] prune_ref(): call `ref_transaction_add_update()` directly Michael Haggerty
2017-11-05 8:42 ` [PATCH v2 3/9] ref_transaction_update(): die on disallowed flags Michael Haggerty
2017-11-07 20:53 ` Martin Ågren [this message]
2017-11-07 22:07 ` Thomas Gummerer
2017-11-05 8:42 ` [PATCH v2 4/9] ref_transaction_add_update(): remove a check Michael Haggerty
2017-11-05 8:42 ` [PATCH v2 5/9] refs: tidy up and adjust visibility of the `ref_update` flags Michael Haggerty
2017-11-05 8:42 ` [PATCH v2 6/9] refs: rename constant `REF_NODEREF` to `REF_NO_DEREF` Michael Haggerty
2017-11-05 8:42 ` [PATCH v2 7/9] refs: rename constant `REF_ISPRUNING` to `REF_IS_PRUNING` Michael Haggerty
2017-11-05 8:42 ` [PATCH v2 8/9] write_packed_entry(): take `object_id` arguments Michael Haggerty
2017-11-05 8:42 ` [PATCH v2 9/9] refs: update some more docs to use "oid" rather than "sha1" Michael Haggerty
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