Re: [PATCH] dir.c: clean the entire struct in clear_exclude_list()

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 28, 2015, 20:47 UTC
Message-ID: <xmqqtwn2jo5d.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <1451181274-26213-1-git-send-email-pclouds@gmail.com>

Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:

> Make sure "el" can be reuseable again. The problem was el->alloc is
> not cleared and may cause segfaults next time because add_exclude()
> thinks el->excludes (being NULL) has enough space. Just clear the
> entire struct to be safe.

OK.

If somebody ever adds a field to this structure that should not be cleared by filling it with '\0', that person would notice and turn this memset() back to individual field assignment, but until then, I think memset is a reasonable thing to do, as that is how it is initialized by add_exclude_list() in the first place anyway.

Will apply.

Show 25 quoted lines

> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
>  This was needed in the worktree config split series because the same
>  exclude_list could be reused. But that series is changing and will not
>  need exclude_list any more. So instead of dropping this patch, I
>  submit it separately. It's a good fix anyway.
>
>  dir.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/dir.c b/dir.c
> index d2a8f06..b8b4576 100644
> --- a/dir.c
> +++ b/dir.c
> @@ -564,9 +564,7 @@ void clear_exclude_list(struct exclude_list *el)
>  	free(el->excludes);
>  	free(el->filebuf);
>  
> -	el->nr = 0;
> -	el->excludes = NULL;
> -	el->filebuf = NULL;
> +	memset(el, 0, sizeof(*el));
>  }
>  
>  static void trim_trailing_spaces(char *buf)