netdev - Re: [PATCH bpf-next] libbpf: silence GCC8 warning about string truncation

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Message-ID: <CAPhsuW7e9Cf69Pc7eR5iYvSo1qDzC_qYwpasfjeU6p9ygC=QwQ@mail.gmail.com>
Date:   Wed, 24 Jul 2019 13:43:55 -0700
From:   Song Liu <liu.song.a23@...il.com>
To:     Andrii Nakryiko <andriin@...com>
Cc:     bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Kernel Team <kernel-team@...com>,
        Magnus Karlsson <magnus.karlsson@...el.com>
Subject: Re: [PATCH bpf-next] libbpf: silence GCC8 warning about string truncation

On Tue, Jul 23, 2019 at 7:33 PM Andrii Nakryiko <andriin@...com> wrote:
>
> Despite a proper NULL-termination after strncpy(..., ..., IFNAMSIZ - 1),
> GCC8 still complains about *expected* string truncation:
>
>   xsk.c:330:2: error: 'strncpy' output may be truncated copying 15 bytes
>   from a string of length 15 [-Werror=stringop-truncation]
>     strncpy(ifr.ifr_name, xsk->ifname, IFNAMSIZ - 1);
>
> This patch gets rid of the issue altogether by using memcpy instead.
> There is no performance regression, as strncpy will still copy and fill
> all of the bytes anyway.
>
> Cc: Magnus Karlsson <magnus.karlsson@...el.com>
> Signed-off-by: Andrii Nakryiko <andriin@...com>

Acked-by: Song Liu <songliubraving@...com>