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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Wed, 21 Sep 2022 17:41:14 -0700
Message-ID: <CAEf4BzbacgBeBrJcutGrpMceD2ipYyvRgrwyKdATN0K39adg5Q@mail.gmail.com>
Subject: Re: [bpf-next v3 1/2] libbpf: Add pathname_concat() helper
To:     Wang Yufen <wangyufen@huawei.com>
Cc:     andrii@kernel.org, ast@kernel.org, daniel@iogearbox.net,
        martin.lau@linux.dev, song@kernel.org, yhs@fb.com,
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        palmer@dabbelt.com, aou@eecs.berkeley.edu, davem@davemloft.net,
        kuba@kernel.org, hawk@kernel.org, nathan@kernel.org,
        ndesaulniers@google.com, trix@redhat.com, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        llvm@lists.linux.dev
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On Sun, Sep 18, 2022 at 7:28 PM Wang Yufen <wangyufen@huawei.com> wrote:
>
> Move snprintf and len check to common helper pathname_concat() to make the
> code simpler.
>
> Signed-off-by: Wang Yufen <wangyufen@huawei.com>
> ---
>  tools/lib/bpf/libbpf.c | 76 +++++++++++++++++++-------------------------------
>  1 file changed, 29 insertions(+), 47 deletions(-)
>

[...]

> @@ -8009,14 +8012,9 @@ int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
>                 char buf[PATH_MAX];
>
>                 if (path) {
> -                       int len;
> -
> -                       len = snprintf(buf, PATH_MAX, "%s/%s", path,
> -                                      bpf_map__name(map));
> -                       if (len < 0)
> -                               return libbpf_err(-EINVAL);
> -                       else if (len >= PATH_MAX)
> -                               return libbpf_err(-ENAMETOOLONG);
> +                       err = pathname_concat(path, bpf_map__name(map), buf, PATH_MAX);
> +                       if (err)
> +                               return err;

also keep libbpf_err() as well, it sets errno properly

>                         sanitize_pin_path(buf);
>                         pin_path = buf;
>                 } else if (!map->pin_path) {
> @@ -8034,6 +8032,7 @@ int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
>  int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
>  {
>         struct bpf_program *prog;
> +       char buf[PATH_MAX];
>         int err;
>
>         if (!obj)

[...]