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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Fri, 26 Mar 2021 16:05:24 -0700
Message-ID: <CAEf4Bzb1z2KOHsMTrSP2t3S0iT3UrYMAWsO1_OqD_EYMECsZ-w@mail.gmail.com>
Subject: Re: [PATCH bpf-next v2 6/6] selftests/bpf: Add a series of tests for bpf_snprintf
To:     Florent Revest <revest@chromium.org>
Cc:     bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Yonghong Song <yhs@fb.com>, KP Singh <kpsingh@kernel.org>,
        Brendan Jackman <jackmanb@chromium.org>,
        open list <linux-kernel@vger.kernel.org>
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On Tue, Mar 23, 2021 at 7:23 PM Florent Revest <revest@chromium.org> wrote:
>
> This exercises most of the format specifiers when things go well.
>
> Signed-off-by: Florent Revest <revest@chromium.org>
> ---

Looks good. Please add a no-argument test case as well.

Acked-by: Andrii Nakryiko <andrii@kernel.org>

>  .../selftests/bpf/prog_tests/snprintf.c       | 65 +++++++++++++++++++
>  .../selftests/bpf/progs/test_snprintf.c       | 59 +++++++++++++++++
>  2 files changed, 124 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/snprintf.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_snprintf.c
>

[...]

> +
> +SEC("raw_tp/sys_enter")
> +int handler(const void *ctx)
> +{
> +       /* Convenient values to pretty-print */
> +       const __u8 ex_ipv4[] = {127, 0, 0, 1};
> +       const __u8 ex_ipv6[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
> +       const char str1[] = "str1";
> +       const char longstr[] = "longstr";
> +       extern const void schedule __ksym;

oh, fancy. I'd move it out of this function into global space, though,
to make it more apparent. I almost missed that it's a special one.

> +
> +       /* Integer types */
> +       num_ret  = BPF_SNPRINTF(num_out, sizeof(num_out),
> +                               "%d %u %x %li %llu %lX",
> +                               -8, 9, 150, -424242, 1337, 0xDABBAD00);
> +       /* IP addresses */
> +       ip_ret   = BPF_SNPRINTF(ip_out, sizeof(ip_out), "%pi4 %pI6",
> +                               &ex_ipv4, &ex_ipv6);
> +       /* Symbol lookup formatting */
> +       sym_ret  = BPF_SNPRINTF(sym_out,  sizeof(sym_out), "%ps %pS %pB",
> +                               &schedule, &schedule, &schedule);
> +       /* Kernel pointers */
> +       addr_ret = BPF_SNPRINTF(addr_out, sizeof(addr_out), "%pK %px %p",
> +                               0, 0xFFFF00000ADD4E55, 0xFFFF00000ADD4E55);
> +       /* Strings embedding */
> +       str_ret  = BPF_SNPRINTF(str_out, sizeof(str_out), "%s %+05s",
> +                               str1, longstr);
> +       /* Overflow */
> +       over_ret = BPF_SNPRINTF(over_out, sizeof(over_out), "%%overflow");
> +
> +       return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> --
> 2.31.0.291.g576ba9dcdaf-goog
>