Subject: Re: [RFC 04/11] coccicheck: detect hashmap_entry.hash assignment

From: Junio C Hamano <[email-masked]>
Date: Mon, 09 Sep 2019 11:15:34 -0700

Eric Wong <[email-masked]> writes:

> Eric Wong <[email-masked]> wrote:
>> By renaming the "hash" field to "_hash", it's easy to spot
>> improper initialization of hashmap_entry structs which
>> can leave "hashmap_entry.next" uninitialized.
>
> Junio, I'm planning to reroll this series.
> (Sorry for not following up sooner)
>
> Would you prefer I drop 04/11 "hashmap_entry: detect improper initialization"
> in favor of the following?  Thanks.

Automation is good ;-)
FWIW, I do not mind the original 04/11 myself too much, though.

Thanks.

> ---------8<--------
> Subject: [PATCH 4/11] coccicheck: detect hashmap_entry.hash assignment
>
> Assigning hashmap_entry.hash manually leaves hashmap_entry.next
> uninitialized, which can be dangerous once the hashmap_entry is
> inserted into a hashmap.   Detect those assignments and use
> hashmap_entry_init, instead.
>
> Signed-off-by: Eric Wong <[email-masked]>
> ---
>  contrib/coccinelle/hashmap.cocci | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>  create mode 100644 contrib/coccinelle/hashmap.cocci
>
> diff --git a/contrib/coccinelle/hashmap.cocci b/contrib/coccinelle/hashmap.cocci
> new file mode 100644
> index 0000000000..d69e120ccf
> --- /dev/null
> +++ b/contrib/coccinelle/hashmap.cocci
> @@ -0,0 +1,16 @@
> +@ hashmap_entry_init_usage @
> +expression E;
> +struct hashmap_entry HME;
> +@@
> +- HME.hash = E;
> ++ hashmap_entry_init(&HME, E);
> +
> +@@
> +identifier f !~ "^hashmap_entry_init$";
> +expression E;
> +struct hashmap_entry *HMEP;
> +@@
> +  f(...) {<...
> +- HMEP->hash = E;
> ++ hashmap_entry_init(HMEP, E);
> +  ...>}