Re: [PATCH] cocci: detect useless free(3) calls

From: Junio C Hamano <gitster@pobox.com>
Date: Feb 11, 2017, 19:01 UTC
Message-ID: <xmqqr334h7rg.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <7e10f934-f084-ceb4-00eb-b75cdb01886b@web.de>

René Scharfe <l.s.r@web.de> writes:

Show 8 quoted lines

> Add a semantic patch for removing checks that cause free(3) to only be
> called with a NULL pointer, as that must be a programming mistake.
>
> Signed-off-by: Rene Scharfe <l.s.r@web.de>
> ---
> No cases are found in master or next, but 1d263b93 (bisect--helper:
> `bisect_next_check` & bisect_voc shell function in C) introduced four
> of them to pu.

Thanks. This should have been caught by code inspection, but having automated way to do so is always good.

Show 18 quoted lines

>
>  contrib/coccinelle/free.cocci | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/contrib/coccinelle/free.cocci b/contrib/coccinelle/free.cocci
> index e28213161a..c03ba737e5 100644
> --- a/contrib/coccinelle/free.cocci
> +++ b/contrib/coccinelle/free.cocci
> @@ -3,3 +3,9 @@ expression E;
>  @@
>  - if (E)
>    free(E);
> +
> +@@
> +expression E;
> +@@
> +- if (!E)
> +  free(E);